diff --git "a/Ada/RM-Final.pdf.txt" "b/Ada/RM-Final.pdf.txt" new file mode 100644--- /dev/null +++ "b/Ada/RM-Final.pdf.txt" @@ -0,0 +1,101546 @@ +Ada Reference Manual, 2012 Edition + +Ada Reference Manual + +2012 Edition + +Language and Standard Libraries + +Copyright © 1992, 1993, 1994, 1995 Intermetrics, Inc. + +Copyright © 2000 The MITRE Corporation, Inc. + +Copyright © 2004, 2005, 2006 AXE Consultants + +Copyright © 2004, 2005, 2006 Ada-Europe + +Copyright © 2008, 2009, 2010, 2011, 2012 AXE Consultants + + + + + + + + + + + + + + + + + + + + + + + + + + + + + Ada Reference Manual - Language and Standard Libraries + +Copyright © 1992, 1993, 1994, 1995, Intermetrics, Inc. + +This copyright is assigned to the U.S. Government. All rights reserved. + +This document may be copied, in whole or in part, in any form or by any means, as is or with alterations, +provided that (1) alterations are clearly marked as alterations and (2) this copyright notice is included +unmodified in any copy. Compiled copies of standard library units and examples need not contain this +copyright notice so long as the notice is included in all copies of source code and documentation. + +Technical Corrigendum 1 + +Copyright © 2000, The MITRE Corporation. All Rights Reserved. + +This document may be copied, in whole or in part, in any form or by any means, as is, or with alterations, +provided that (1) alterations are clearly marked as alterations and (2) this copyright notice is included +unmodified in any copy. Any other use or distribution of this document is prohibited without the prior +express permission of MITRE. + +You use this document on the condition that you indemnify and hold harmless MITRE, its Board of +Trustees, officers, agents, and employees, from any and all liability or damages to yourself or your +hardware or software, or third parties, including attorneys' fees, court costs, and other related costs and +expenses, arising out of your use of this document irrespective of the cause of said liability. + +MITRE MAKES THIS DOCUMENT AVAILABLE ON AN "AS IS" BASIS AND MAKES NO +WARRANTY, EXPRESS OR IMPLIED, AS TO THE ACCURACY, CAPABILITY, EFFICIENCY +MERCHANTABILITY, OR FUNCTIONING OF THIS DOCUMENT. IN NO EVENT WILL MITRE +BE LIABLE FOR ANY GENERAL, CONSEQUENTIAL, INDIRECT, INCIDENTAL, EXEMPLARY, +OR SPECIAL DAMAGES, EVEN IF MITRE HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH +DAMAGES. + +Amendment 1 + +Copyright © 2004, 2005, 2006, 2007, AXE Consultants. All Rights Reserved. + +This document may be copied, in whole or in part, in any form or by any means, as is, or with alterations, +provided that (1) alterations are clearly marked as alterations and (2) this copyright notice is included +unmodified in any copy. Any other use or distribution of this document is prohibited without the prior +express permission of AXE. + +You use this document on the condition that you indemnify and hold harmless AXE, its board, officers, +agents, and employees, from any and all liability or damages to yourself or your hardware or software, or + + + + + + + + + + + third parties, including attorneys' fees, court costs, and other related costs and expenses, arising out of your +use of this document irrespective of the cause of said liability. + +AXE MAKES THIS DOCUMENT AVAILABLE ON AN "AS IS" BASIS AND MAKES NO +WARRANTY, EXPRESS OR IMPLIED, AS TO THE ACCURACY, CAPABILITY, EFFICIENCY +MERCHANTABILITY, OR FUNCTIONING OF THIS DOCUMENT. IN NO EVENT WILL AXE BE +LIABLE FOR ANY GENERAL, CONSEQUENTIAL, INDIRECT, INCIDENTAL, EXEMPLARY, OR +SPECIAL DAMAGES, EVEN IF AXE HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH +DAMAGES. + +Third Edition + +Copyright © 2008, 2009, 2010, 2011, 2012 AXE Consultants. All Rights Reserved. + +This document may be copied, in whole or in part, in any form or by any means, as is, or with alterations, +provided that (1) alterations are clearly marked as alterations and (2) this copyright notice is included +unmodified in any copy. Any other use or distribution of this document is prohibited without the prior +express permission of AXE. + +You use this document on the condition that you indemnify and hold harmless AXE, its board, officers, +agents, and employees, from any and all liability or damages to yourself or your hardware or software, or +third parties, including attorneys' fees, court costs, and other related costs and expenses, arising out of your +use of this document irrespective of the cause of said liability. + +AXE MAKES THIS DOCUMENT AVAILABLE ON AN "AS IS" BASIS AND MAKES NO +WARRANTY, EXPRESS OR IMPLIED, AS TO THE ACCURACY, CAPABILITY, EFFICIENCY +MERCHANTABILITY, OR FUNCTIONING OF THIS DOCUMENT. IN NO EVENT WILL AXE BE +LIABLE FOR ANY GENERAL, CONSEQUENTIAL, INDIRECT, INCIDENTAL, EXEMPLARY, OR +SPECIAL DAMAGES, EVEN IF AXE HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH +DAMAGES. + +Ada 2005 Consolidated Standard + +Copyright © 2004, 2005, 2006, Ada-Europe. + +This document may be copied, in whole or in part, in any form or by any means, as is, or with alterations, +provided that (1) alterations are clearly marked as alterations and (2) this copyright notice is included +unmodified in any copy. Any other use or distribution of this document is prohibited without the prior +express permission of Ada-Europe. + +You use this document on the condition that you indemnify and hold harmless Ada-Europe and its Board +from any and all liability or damages to yourself or your hardware or software, or third parties, including +attorneys' fees, court costs, and other related costs and expenses, arising out of your use of this document +irrespective of the cause of said liability. + +ADA-EUROPE MAKES THIS DOCUMENT AVAILABLE ON AN "AS IS" BASIS AND MAKES NO +WARRANTY, EXPRESS OR IMPLIED, AS TO THE ACCURACY, CAPABILITY, EFFICIENCY +MERCHANTABILITY, OR FUNCTIONING OF THIS DOCUMENT. IN NO EVENT WILL ADA- +EUROPE BE LIABLE FOR ANY GENERAL, CONSEQUENTIAL, INDIRECT, INCIDENTAL, +EXEMPLARY, OR SPECIAL DAMAGES, EVEN IF ADA-EUROPE HAS BEEN ADVISED OF THE +POSSIBILITY OF SUCH DAMAGES. + + + Ada Reference Manual — 2012 Edition + +Table of Contents +Table of Contents............................................................................................................i +Introduction ...................................................................................................................xi +1 General.......................................................................................................................1 +1.1 Scope .............................................................................................................................................1 +1.1.1 Extent ......................................................................................................................................1 +1.1.2 Structure .................................................................................................................................2 +1.1.3 Conformity of an Implementation with the Standard.........................................................4 +1.1.4 Method of Description and Syntax Notation.......................................................................5 +1.1.5 Classification of Errors .........................................................................................................6 +1.2 Normative References ..................................................................................................................7 +1.3 Terms and Definitions ..................................................................................................................8 +2 Lexical Elements .......................................................................................................9 +2.1 Character Set.................................................................................................................................9 +2.2 Lexical Elements, Separators, and Delimiters.........................................................................11 +2.3 Identifiers .....................................................................................................................................12 +2.4 Numeric Literals ..........................................................................................................................13 +2.4.1 Decimal Literals ...................................................................................................................13 +2.4.2 Based Literals ......................................................................................................................14 +2.5 Character Literals .......................................................................................................................14 +2.6 String Literals ..............................................................................................................................15 +2.7 Comments....................................................................................................................................15 +2.8 Pragmas .......................................................................................................................................16 +2.9 Reserved Words..........................................................................................................................18 +3 Declarations and Types..........................................................................................19 +3.1 Declarations.................................................................................................................................19 +3.2 Types and Subtypes ...................................................................................................................20 +3.2.1 Type Declarations................................................................................................................22 +3.2.2 Subtype Declarations ..........................................................................................................23 +3.2.3 Classification of Operations...............................................................................................24 +3.2.4 Subtype Predicates .............................................................................................................25 +3.3 Objects and Named Numbers....................................................................................................27 +3.3.1 Object Declarations .............................................................................................................29 +3.3.2 Number Declarations...........................................................................................................31 +3.4 Derived Types and Classes .......................................................................................................32 +3.4.1 Derivation Classes...............................................................................................................35 +3.5 Scalar Types ................................................................................................................................37 +3.5.1 Enumeration Types .............................................................................................................42 +3.5.2 Character Types...................................................................................................................43 +3.5.3 Boolean Types .....................................................................................................................44 +3.5.4 Integer Types .......................................................................................................................44 +3.5.5 Operations of Discrete Types.............................................................................................47 +3.5.6 Real Types ............................................................................................................................48 +3.5.7 Floating Point Types ...........................................................................................................49 +3.5.8 Operations of Floating Point Types...................................................................................51 +3.5.9 Fixed Point Types ................................................................................................................51 +3.5.10 Operations of Fixed Point Types .....................................................................................53 + +i 13 December 2012 + +Table of Contents + + Ada Reference Manual — 2012 Edition + +3.6 Array Types ................................................................................................................................. 54 +3.6.1 Index Constraints and Discrete Ranges ........................................................................... 57 +3.6.2 Operations of Array Types ................................................................................................. 58 +3.6.3 String Types......................................................................................................................... 59 +3.7 Discriminants .............................................................................................................................. 60 +3.7.1 Discriminant Constraints ................................................................................................... 62 +3.7.2 Operations of Discriminated Types .................................................................................. 63 +3.8 Record Types.............................................................................................................................. 64 +3.8.1 Variant Parts and Discrete Choices .................................................................................. 66 +3.9 Tagged Types and Type Extensions ........................................................................................ 68 +3.9.1 Type Extensions.................................................................................................................. 72 +3.9.2 Dispatching Operations of Tagged Types........................................................................ 73 +3.9.3 Abstract Types and Subprograms .................................................................................... 76 +3.9.4 Interface Types .................................................................................................................... 77 +3.10 Access Types............................................................................................................................ 80 +3.10.1 Incomplete Type Declarations ......................................................................................... 82 +3.10.2 Operations of Access Types............................................................................................ 85 +3.11 Declarative Parts ...................................................................................................................... 91 +3.11.1 Completions of Declarations ........................................................................................... 91 +4 Names and Expressions ........................................................................................ 93 +4.1 Names .......................................................................................................................................... 93 +4.1.1 Indexed Components.......................................................................................................... 94 +4.1.2 Slices .................................................................................................................................... 95 +4.1.3 Selected Components ........................................................................................................ 96 +4.1.4 Attributes.............................................................................................................................. 98 +4.1.5 User-Defined References ................................................................................................... 99 +4.1.6 User-Defined Indexing ...................................................................................................... 100 +4.2 Literals ....................................................................................................................................... 102 +4.3 Aggregates ................................................................................................................................ 103 +4.3.1 Record Aggregates ........................................................................................................... 103 +4.3.2 Extension Aggregates ...................................................................................................... 105 +4.3.3 Array Aggregates .............................................................................................................. 107 +4.4 Expressions .............................................................................................................................. 110 +4.5 Operators and Expression Evaluation ................................................................................... 111 +4.5.1 Logical Operators and Short-circuit Control Forms ..................................................... 112 +4.5.2 Relational Operators and Membership Tests ................................................................ 113 +4.5.3 Binary Adding Operators ................................................................................................. 117 +4.5.4 Unary Adding Operators .................................................................................................. 118 +4.5.5 Multiplying Operators ....................................................................................................... 118 +4.5.6 Highest Precedence Operators ....................................................................................... 121 +4.5.7 Conditional Expressions .................................................................................................. 122 +4.5.8 Quantified Expressions .................................................................................................... 123 +4.6 Type Conversions .................................................................................................................... 124 +4.7 Qualified Expressions.............................................................................................................. 129 +4.8 Allocators .................................................................................................................................. 129 +4.9 Static Expressions and Static Subtypes................................................................................ 132 +4.9.1 Statically Matching Constraints and Subtypes.............................................................. 136 +5 Statements............................................................................................................. 137 +5.1 Simple and Compound Statements - Sequences of Statements ........................................ 137 +5.2 Assignment Statements........................................................................................................... 138 +5.3 If Statements ............................................................................................................................. 140 +5.4 Case Statements....................................................................................................................... 141 + +Table of Contents + +13 December 2012 ii + + Ada Reference Manual — 2012 Edition + +5.5 Loop Statements.......................................................................................................................142 +5.5.1 User-Defined Iterator Types .............................................................................................144 +5.5.2 Generalized Loop Iteration ...............................................................................................145 +5.6 Block Statements......................................................................................................................147 +5.7 Exit Statements .........................................................................................................................147 +5.8 Goto Statements .......................................................................................................................148 +6 Subprograms.........................................................................................................151 +6.1 Subprogram Declarations ........................................................................................................151 +6.1.1 Preconditions and Postconditions ..................................................................................154 +6.2 Formal Parameter Modes .........................................................................................................157 +6.3 Subprogram Bodies..................................................................................................................158 +6.3.1 Conformance Rules...........................................................................................................159 +6.3.2 Inline Expansion of Subprograms ...................................................................................161 +6.4 Subprogram Calls .....................................................................................................................161 +6.4.1 Parameter Associations....................................................................................................163 +6.5 Return Statements ....................................................................................................................166 +6.5.1 Nonreturning Procedures .................................................................................................169 +6.6 Overloading of Operators ........................................................................................................170 +6.7 Null Procedures ........................................................................................................................171 +6.8 Expression Functions ..............................................................................................................172 +7 Packages................................................................................................................173 +7.1 Package Specifications and Declarations..............................................................................173 +7.2 Package Bodies ........................................................................................................................174 +7.3 Private Types and Private Extensions....................................................................................175 +7.3.1 Private Operations.............................................................................................................178 +7.3.2 Type Invariants...................................................................................................................180 +7.4 Deferred Constants...................................................................................................................182 +7.5 Limited Types ............................................................................................................................183 +7.6 Assignment and Finalization ...................................................................................................185 +7.6.1 Completion and Finalization.............................................................................................187 +8 Visibility Rules.......................................................................................................191 +8.1 Declarative Region....................................................................................................................191 +8.2 Scope of Declarations ..............................................................................................................192 +8.3 Visibility......................................................................................................................................193 +8.3.1 Overriding Indicators ........................................................................................................196 +8.4 Use Clauses...............................................................................................................................197 +8.5 Renaming Declarations ............................................................................................................198 +8.5.1 Object Renaming Declarations ........................................................................................198 +8.5.2 Exception Renaming Declarations ..................................................................................200 +8.5.3 Package Renaming Declarations.....................................................................................200 +8.5.4 Subprogram Renaming Declarations ..............................................................................201 +8.5.5 Generic Renaming Declarations ......................................................................................203 +8.6 The Context of Overload Resolution ......................................................................................203 +9 Tasks and Synchronization .................................................................................207 +9.1 Task Units and Task Objects...................................................................................................207 +9.2 Task Execution - Task Activation............................................................................................210 +9.3 Task Dependence - Termination of Tasks..............................................................................211 +9.4 Protected Units and Protected Objects ..................................................................................213 +9.5 Intertask Communication.........................................................................................................216 +9.5.1 Protected Subprograms and Protected Actions ............................................................218 + +iii 13 December 2012 + +Table of Contents + + Ada Reference Manual — 2012 Edition + +9.5.2 Entries and Accept Statements ....................................................................................... 219 +9.5.3 Entry Calls.......................................................................................................................... 222 +9.5.4 Requeue Statements......................................................................................................... 225 +9.6 Delay Statements, Duration, and Time................................................................................... 226 +9.6.1 Formatting, Time Zones, and other operations for Time .............................................. 229 +9.7 Select Statements..................................................................................................................... 235 +9.7.1 Selective Accept ................................................................................................................ 236 +9.7.2 Timed Entry Calls .............................................................................................................. 238 +9.7.3 Conditional Entry Calls..................................................................................................... 239 +9.7.4 Asynchronous Transfer of Control ................................................................................. 239 +9.8 Abort of a Task - Abort of a Sequence of Statements .......................................................... 240 +9.9 Task and Entry Attributes........................................................................................................ 242 +9.10 Shared Variables .................................................................................................................... 242 +9.11 Example of Tasking and Synchronization ........................................................................... 244 +10 Program Structure and Compilation Issues .................................................... 247 +10.1 Separate Compilation............................................................................................................. 247 +10.1.1 Compilation Units - Library Units .................................................................................. 247 +10.1.2 Context Clauses - With Clauses .................................................................................... 250 +10.1.3 Subunits of Compilation Units ...................................................................................... 252 +10.1.4 The Compilation Process ............................................................................................... 254 +10.1.5 Pragmas and Program Units.......................................................................................... 255 +10.1.6 Environment-Level Visibility Rules ............................................................................... 256 +10.2 Program Execution................................................................................................................. 257 +10.2.1 Elaboration Control......................................................................................................... 259 +11 Exceptions........................................................................................................... 263 +11.1 Exception Declarations.......................................................................................................... 263 +11.2 Exception Handlers ................................................................................................................ 264 +11.3 Raise Statements.................................................................................................................... 265 +11.4 Exception Handling ................................................................................................................ 265 +11.4.1 The Package Exceptions ................................................................................................ 266 +11.4.2 Pragmas Assert and Assertion_Policy ......................................................................... 268 +11.4.3 Example of Exception Handling .................................................................................... 271 +11.5 Suppressing Checks.............................................................................................................. 272 +11.6 Exceptions and Optimization ................................................................................................ 275 +12 Generic Units....................................................................................................... 277 +12.1 Generic Declarations.............................................................................................................. 277 +12.2 Generic Bodies ....................................................................................................................... 279 +12.3 Generic Instantiation.............................................................................................................. 280 +12.4 Formal Objects ....................................................................................................................... 282 +12.5 Formal Types .......................................................................................................................... 284 +12.5.1 Formal Private and Derived Types ................................................................................ 285 +12.5.2 Formal Scalar Types ....................................................................................................... 288 +12.5.3 Formal Array Types......................................................................................................... 288 +12.5.4 Formal Access Types ..................................................................................................... 289 +12.5.5 Formal Interface Types................................................................................................... 290 +12.6 Formal Subprograms ............................................................................................................. 290 +12.7 Formal Packages .................................................................................................................... 293 +12.8 Example of a Generic Package ............................................................................................. 295 +13 Representation Issues ....................................................................................... 297 +13.1 Operational and Representation Aspects............................................................................ 297 + +Table of Contents + +13 December 2012 iv + + Ada Reference Manual — 2012 Edition + +13.1.1 Aspect Specifications .....................................................................................................300 +13.2 Packed Types ..........................................................................................................................303 +13.3 Operational and Representation Attributes .........................................................................304 +13.4 Enumeration Representation Clauses..................................................................................310 +13.5 Record Layout .........................................................................................................................311 +13.5.1 Record Representation Clauses ....................................................................................312 +13.5.2 Storage Place Attributes .................................................................................................314 +13.5.3 Bit Ordering ......................................................................................................................315 +13.6 Change of Representation .....................................................................................................316 +13.7 The Package System ..............................................................................................................317 +13.7.1 The Package System.Storage_Elements ......................................................................319 +13.7.2 The Package System.Address_To_Access_Conversions ..........................................320 +13.8 Machine Code Insertions .......................................................................................................320 +13.9 Unchecked Type Conversions ..............................................................................................321 +13.9.1 Data Validity .....................................................................................................................322 +13.9.2 The Valid Attribute...........................................................................................................324 +13.10 Unchecked Access Value Creation.....................................................................................324 +13.11 Storage Management............................................................................................................325 +13.11.1 Storage Allocation Attributes .......................................................................................328 +13.11.2 Unchecked Storage Deallocation ................................................................................329 +13.11.3 Default Storage Pools ...................................................................................................330 +13.11.4 Storage Subpools ..........................................................................................................331 +13.11.5 Subpool Reclamation....................................................................................................333 +13.11.6 Storage Subpool Example ............................................................................................334 +13.12 Pragma Restrictions and Pragma Profile...........................................................................336 +13.12.1 Language-Defined Restrictions and Profiles .............................................................338 +13.13 Streams ..................................................................................................................................340 +13.13.1 The Package Streams ...................................................................................................340 +13.13.2 Stream-Oriented Attributes ..........................................................................................341 +13.14 Freezing Rules ......................................................................................................................346 +The Standard Libraries ..............................................................................................349 +Annex A (normative) Predefined Language Environment ......................................351 +A.1 The Package Standard.............................................................................................................354 +A.2 The Package Ada......................................................................................................................358 +A.3 Character Handling ..................................................................................................................358 +A.3.1 The Packages Characters, Wide_Characters, and Wide_Wide_Characters...............359 +A.3.2 The Package Characters.Handling..................................................................................359 +A.3.3 The Package Characters.Latin_1.....................................................................................362 +A.3.4 The Package Characters.Conversions ...........................................................................367 +A.3.5 The Package Wide_Characters.Handling .......................................................................369 +A.3.6 The Package Wide_Wide_Characters.Handling ............................................................371 +A.4 String Handling.........................................................................................................................372 +A.4.1 The Package Strings.........................................................................................................372 +A.4.2 The Package Strings.Maps ..............................................................................................372 +A.4.3 Fixed-Length String Handling..........................................................................................375 +A.4.4 Bounded-Length String Handling ...................................................................................384 +A.4.5 Unbounded-Length String Handling...............................................................................391 +A.4.6 String-Handling Sets and Mappings ...............................................................................396 +A.4.7 Wide_String Handling.......................................................................................................397 +A.4.8 Wide_Wide_String Handling ............................................................................................399 +A.4.9 String Hashing...................................................................................................................402 +A.4.10 String Comparison..........................................................................................................403 + +v 13 December 2012 + +Table of Contents + + Ada Reference Manual — 2012 Edition + +A.4.11 String Encoding .............................................................................................................. 404 +A.5 The Numerics Packages.......................................................................................................... 409 +A.5.1 Elementary Functions ...................................................................................................... 410 +A.5.2 Random Number Generation........................................................................................... 413 +A.5.3 Attributes of Floating Point Types.................................................................................. 418 +A.5.4 Attributes of Fixed Point Types ...................................................................................... 422 +A.6 Input-Output ............................................................................................................................. 423 +A.7 External Files and File Objects............................................................................................... 423 +A.8 Sequential and Direct Files ..................................................................................................... 424 +A.8.1 The Generic Package Sequential_IO .............................................................................. 425 +A.8.2 File Management............................................................................................................... 426 +A.8.3 Sequential Input-Output Operations .............................................................................. 428 +A.8.4 The Generic Package Direct_IO ...................................................................................... 428 +A.8.5 Direct Input-Output Operations....................................................................................... 429 +A.9 The Generic Package Storage_IO .......................................................................................... 430 +A.10 Text Input-Output................................................................................................................... 431 +A.10.1 The Package Text_IO ..................................................................................................... 432 +A.10.2 Text File Management .................................................................................................... 437 +A.10.3 Default Input, Output, and Error Files .......................................................................... 438 +A.10.4 Specification of Line and Page Lengths ...................................................................... 439 +A.10.5 Operations on Columns, Lines, and Pages ................................................................. 440 +A.10.6 Get and Put Procedures................................................................................................. 443 +A.10.7 Input-Output of Characters and Strings....................................................................... 445 +A.10.8 Input-Output for Integer Types...................................................................................... 447 +A.10.9 Input-Output for Real Types .......................................................................................... 448 +A.10.10 Input-Output for Enumeration Types ......................................................................... 451 +A.10.11 Input-Output for Bounded Strings.............................................................................. 452 +A.10.12 Input-Output for Unbounded Strings ......................................................................... 454 +A.11 Wide Text Input-Output and Wide Wide Text Input-Output............................................... 455 +A.12 Stream Input-Output .............................................................................................................. 456 +A.12.1 The Package Streams.Stream_IO ................................................................................. 456 +A.12.2 The Package Text_IO.Text_Streams............................................................................. 458 +A.12.3 The Package Wide_Text_IO.Text_Streams .................................................................. 459 +A.12.4 The Package Wide_Wide_Text_IO.Text_Streams ....................................................... 459 +A.13 Exceptions in Input-Output................................................................................................... 459 +A.14 File Sharing............................................................................................................................. 461 +A.15 The Package Command_Line............................................................................................... 461 +A.16 The Package Directories ....................................................................................................... 462 +A.16.1 The Package Directories.Hierarchical_File_Names.................................................... 470 +A.17 The Package Environment_Variables.................................................................................. 472 +A.18 Containers .............................................................................................................................. 475 +A.18.1 The Package Containers................................................................................................ 475 +A.18.2 The Generic Package Containers.Vectors ................................................................... 475 +A.18.3 The Generic Package Containers.Doubly_Linked_Lists............................................ 493 +A.18.4 Maps................................................................................................................................. 504 +A.18.5 The Generic Package Containers.Hashed_Maps........................................................ 511 +A.18.6 The Generic Package Containers.Ordered_Maps....................................................... 515 +A.18.7 Sets .................................................................................................................................. 519 +A.18.8 The Generic Package Containers.Hashed_Sets ......................................................... 527 +A.18.9 The Generic Package Containers.Ordered_Sets ........................................................ 532 +A.18.10 The Generic Package Containers.Multiway_Trees ................................................... 538 +A.18.11 The Generic Package Containers.Indefinite_Vectors............................................... 552 +A.18.12 The Generic Package Containers.Indefinite_Doubly_Linked_Lists ....................... 553 + +Table of Contents + +13 December 2012 vi + + Ada Reference Manual — 2012 Edition + +A.18.13 The Generic Package Containers.Indefinite_Hashed_Maps ....................................553 +A.18.14 The Generic Package Containers.Indefinite_Ordered_Maps ...................................554 +A.18.15 The Generic Package Containers.Indefinite_Hashed_Sets......................................554 +A.18.16 The Generic Package Containers.Indefinite_Ordered_Sets.....................................554 +A.18.17 The Generic Package Containers.Indefinite_Multiway_Trees .................................555 +A.18.18 The Generic Package Containers.Indefinite_Holders ...............................................555 +A.18.19 The Generic Package Containers.Bounded_Vectors ...............................................559 +A.18.20 The Generic Package Containers.Bounded_Doubly_Linked_Lists ........................560 +A.18.21 The Generic Package Containers.Bounded_Hashed_Maps ....................................561 +A.18.22 The Generic Package Containers.Bounded_Ordered_Maps ...................................562 +A.18.23 The Generic Package Containers.Bounded_Hashed_Sets ......................................563 +A.18.24 The Generic Package Containers.Bounded_Ordered_Sets .....................................565 +A.18.25 The Generic Package Containers.Bounded_Multiway_Trees..................................566 +A.18.26 Array Sorting .................................................................................................................568 +A.18.27 The Generic Package Containers.Synchronized_Queue_Interfaces ......................569 +A.18.28 The Generic Package Containers.Unbounded_Synchronized_Queues .................570 +A.18.29 The Generic Package Containers.Bounded_Synchronized_Queues......................571 +A.18.30 The Generic Package Containers.Unbounded_Priority_Queues ............................572 +A.18.31 The Generic Package Containers.Bounded_Priority_Queues.................................573 +A.18.32 Example of Container Use ...........................................................................................574 +A.19 The Package Locales .............................................................................................................576 +Annex B (normative) Interface to Other Languages................................................579 +B.1 Interfacing Aspects ..................................................................................................................579 +B.2 The Package Interfaces ...........................................................................................................582 +B.3 Interfacing with C and C++......................................................................................................583 +B.3.1 The Package Interfaces.C.Strings...................................................................................591 +B.3.2 The Generic Package Interfaces.C.Pointers ..................................................................594 +B.3.3 Unchecked Union Types ..................................................................................................597 +B.4 Interfacing with COBOL...........................................................................................................599 +B.5 Interfacing with Fortran ...........................................................................................................605 +Annex C (normative) Systems Programming ...........................................................609 +C.1 Access to Machine Operations ...............................................................................................609 +C.2 Required Representation Support..........................................................................................610 +C.3 Interrupt Support......................................................................................................................610 +C.3.1 Protected Procedure Handlers ........................................................................................612 +C.3.2 The Package Interrupts ....................................................................................................614 +C.4 Preelaboration Requirements .................................................................................................616 +C.5 Pragma Discard_Names ..........................................................................................................617 +C.6 Shared Variable Control ..........................................................................................................618 +C.7 Task Information ......................................................................................................................620 +C.7.1 The Package Task_Identification ....................................................................................620 +C.7.2 The Package Task_Attributes..........................................................................................622 +C.7.3 The Package Task_Termination ......................................................................................624 +Annex D (normative) Real-Time Systems .................................................................627 +D.1 Task Priorities...........................................................................................................................627 +D.2 Priority Scheduling ..................................................................................................................629 +D.2.1 The Task Dispatching Model ...........................................................................................629 +D.2.2 Task Dispatching Pragmas ..............................................................................................631 +D.2.3 Preemptive Dispatching ...................................................................................................632 +D.2.4 Non-Preemptive Dispatching...........................................................................................633 +D.2.5 Round Robin Dispatching................................................................................................635 + +vii 13 December 2012 + +Table of Contents + + Ada Reference Manual — 2012 Edition + +D.2.6 Earliest Deadline First Dispatching ................................................................................ 636 +D.3 Priority Ceiling Locking........................................................................................................... 638 +D.4 Entry Queuing Policies............................................................................................................ 640 +D.5 Dynamic Priorities ................................................................................................................... 642 +D.5.1 Dynamic Priorities for Tasks ........................................................................................... 642 +D.5.2 Dynamic Priorities for Protected Objects ...................................................................... 643 +D.6 Preemptive Abort ..................................................................................................................... 644 +D.7 Tasking Restrictions................................................................................................................ 645 +D.8 Monotonic Time ....................................................................................................................... 647 +D.9 Delay Accuracy ........................................................................................................................ 651 +D.10 Synchronous Task Control................................................................................................... 652 +D.10.1 Synchronous Barriers.................................................................................................... 653 +D.11 Asynchronous Task Control................................................................................................. 654 +D.12 Other Optimizations and Determinism Rules ..................................................................... 655 +D.13 The Ravenscar Profile ........................................................................................................... 656 +D.14 Execution Time ...................................................................................................................... 657 +D.14.1 Execution Time Timers .................................................................................................. 659 +D.14.2 Group Execution Time Budgets.................................................................................... 661 +D.14.3 Execution Time of Interrupt Handlers .......................................................................... 663 +D.15 Timing Events......................................................................................................................... 664 +D.16 Multiprocessor Implementation ........................................................................................... 666 +D.16.1 Multiprocessor Dispatching Domains.......................................................................... 667 +Annex E (normative) Distributed Systems ............................................................... 671 +E.1 Partitions................................................................................................................................... 671 +E.2 Categorization of Library Units .............................................................................................. 673 +E.2.1 Shared Passive Library Units .......................................................................................... 674 +E.2.2 Remote Types Library Units ............................................................................................ 674 +E.2.3 Remote Call Interface Library Units................................................................................ 676 +E.3 Consistency of a Distributed System .................................................................................... 677 +E.4 Remote Subprogram Calls...................................................................................................... 677 +E.4.1 Asynchronous Remote Calls........................................................................................... 679 +E.4.2 Example of Use of a Remote Access-to-Class-Wide Type........................................... 680 +E.5 Partition Communication Subsystem.................................................................................... 682 +Annex F (normative) Information Systems............................................................... 685 +F.1 Machine_Radix Attribute Definition Clause .......................................................................... 685 +F.2 The Package Decimal............................................................................................................... 686 +F.3 Edited Output for Decimal Types ........................................................................................... 687 +F.3.1 Picture String Formation.................................................................................................. 688 +F.3.2 Edited Output Generation ................................................................................................ 692 +F.3.3 The Package Text_IO.Editing........................................................................................... 696 +F.3.4 The Package Wide_Text_IO.Editing................................................................................ 699 +F.3.5 The Package Wide_Wide_Text_IO.Editing ..................................................................... 699 +Annex G (normative) Numerics ................................................................................. 701 +G.1 Complex Arithmetic................................................................................................................. 701 +G.1.1 Complex Types ................................................................................................................. 701 +G.1.2 Complex Elementary Functions ..................................................................................... 706 +G.1.3 Complex Input-Output ..................................................................................................... 709 +G.1.4 The Package Wide_Text_IO.Complex_IO ...................................................................... 712 +G.1.5 The Package Wide_Wide_Text_IO.Complex_IO............................................................ 712 +G.2 Numeric Performance Requirements .................................................................................... 712 +G.2.1 Model of Floating Point Arithmetic................................................................................. 713 + +Table of Contents + +13 December 2012 viii + + Ada Reference Manual — 2012 Edition + +G.2.2 Model-Oriented Attributes of Floating Point Types ......................................................714 +G.2.3 Model of Fixed Point Arithmetic......................................................................................715 +G.2.4 Accuracy Requirements for the Elementary Functions ...............................................717 +G.2.5 Performance Requirements for Random Number Generation ....................................719 +G.2.6 Accuracy Requirements for Complex Arithmetic..........................................................719 +G.3 Vector and Matrix Manipulation..............................................................................................721 +G.3.1 Real Vectors and Matrices ...............................................................................................721 +G.3.2 Complex Vectors and Matrices .......................................................................................726 +Annex H (normative) High Integrity Systems ...........................................................739 +H.1 Pragma Normalize_Scalars .....................................................................................................739 +H.2 Documentation of Implementation Decisions.......................................................................740 +H.3 Reviewable Object Code .........................................................................................................740 +H.3.1 Pragma Reviewable ..........................................................................................................740 +H.3.2 Pragma Inspection_Point.................................................................................................741 +H.4 High Integrity Restrictions ......................................................................................................742 +H.5 Pragma Detect_Blocking .........................................................................................................744 +H.6 Pragma Partition_Elaboration_Policy ....................................................................................745 +Annex J (normative) Obsolescent Features .............................................................747 +J.1 Renamings of Library Units .....................................................................................................747 +J.2 Allowed Replacements of Characters ....................................................................................747 +J.3 Reduced Accuracy Subtypes ..................................................................................................748 +J.4 The Constrained Attribute........................................................................................................749 +J.5 ASCII...........................................................................................................................................749 +J.6 Numeric_Error ...........................................................................................................................750 +J.7 At Clauses..................................................................................................................................750 +J.7.1 Interrupt Entries.................................................................................................................750 +J.8 Mod Clauses ..............................................................................................................................752 +J.9 The Storage_Size Attribute ......................................................................................................752 +J.10 Specific Suppression of Checks ...........................................................................................752 +J.11 The Class Attribute of Untagged Incomplete Types ...........................................................753 +J.12 Pragma Interface.....................................................................................................................753 +J.13 Dependence Restriction Identifiers ......................................................................................753 +J.14 Character and Wide_Character Conversion Functions......................................................754 +J.15 Aspect-related Pragmas.........................................................................................................754 +J.15.1 Pragma Inline ...................................................................................................................754 +J.15.2 Pragma No_Return ..........................................................................................................755 +J.15.3 Pragma Pack ....................................................................................................................755 +J.15.4 Pragma Storage_Size......................................................................................................755 +J.15.5 Interfacing Pragmas ........................................................................................................756 +J.15.6 Pragma Unchecked_Union .............................................................................................757 +J.15.7 Pragmas Interrupt_Handler and Attach_Handler.........................................................757 +J.15.8 Shared Variable Pragmas ...............................................................................................758 +J.15.9 Pragma CPU .....................................................................................................................758 +J.15.10 Pragma Dispatching_Domain ......................................................................................759 +J.15.11 Pragmas Priority and Interrupt_Priority......................................................................759 +J.15.12 Pragma Relative_Deadline............................................................................................760 +J.15.13 Pragma Asynchronous .................................................................................................760 +Annex K (informative) Language-Defined Aspects and Attributes ........................761 +K.1 Language-Defined Aspects .....................................................................................................761 +K.2 Language-Defined Attributes ..................................................................................................764 +Annex L (informative) Language-Defined Pragmas .................................................781 + +ix 13 December 2012 + +Table of Contents + + Ada Reference Manual — 2012 Edition + +Annex M (informative) Summary of Documentation Requirements ...................... 785 +M.1 Specific Documentation Requirements ................................................................................ 785 +M.2 Implementation-Defined Characteristics .............................................................................. 787 +M.3 Implementation Advice ........................................................................................................... 794 +Annex N (informative) Glossary................................................................................. 803 +Annex P (informative) Syntax Summary ................................................................... 809 +Annex Q (informative) Language-Defined Entities .................................................. 843 +Q.1 Language-Defined Packages.................................................................................................. 843 +Q.2 Language-Defined Types and Subtypes ............................................................................... 846 +Q.3 Language-Defined Subprograms........................................................................................... 850 +Q.4 Language-Defined Exceptions ............................................................................................... 861 +Q.5 Language-Defined Objects ..................................................................................................... 862 +Index............................................................................................................................ 867 + +Table of Contents + +13 December 2012 x + + + Ada Reference Manual — 2012 Edition + +Introduction + +This is the Ada Reference Manual. + +Other available Ada documents include: + +• Ada 2012 Rationale. This gives an introduction to the changes and new features in Ada 2012, +and explains the rationale behind them. Programmers should read this rationale before reading +this Standard in depth. Rationales for Ada 83, Ada 95, and Ada 2005 are also available. + +• This paragraph was deleted. +• The Annotated Ada Reference Manual (AARM). The AARM contains all of the text in this +International Standard, plus various annotations. It is intended primarily for compiler writers, +validation test writers, and others who wish to study the fine details. The annotations include +detailed rationale for individual rules and explanations of some of the more arcane interactions +among the rules. + +Design Goals + +Ada was originally designed with three overriding concerns: program reliability and maintenance, +programming as a human activity, and efficiency. The 1995 revision to the language was designed to +provide greater flexibility and extensibility, additional control over storage management and +synchronization, and standardized packages oriented toward supporting important application areas, while +at the same time retaining the original emphasis on reliability, maintainability, and efficiency. This third +edition provides further flexibility and adds more standardized packages within the framework provided +by the 1995 revision. + +The need for languages that promote reliability and simplify maintenance is well established. Hence +emphasis was placed on program readability over ease of writing. For example, the rules of the language +require that program variables be explicitly declared and that their type be specified. Since the type of a +variable is invariant, compilers can ensure that operations on variables are compatible with the properties +intended for objects of the type. Furthermore, error-prone notations have been avoided, and the syntax of +the language avoids the use of encoded forms in favor of more English-like constructs. Finally, the +language offers support for separate compilation of program units in a way that facilitates program +development and maintenance, and which provides the same degree of checking between units as within a +unit. + +Concern for the human programmer was also stressed during the design. Above all, an attempt was made +to keep to a relatively small number of underlying concepts integrated in a consistent and systematic way +while continuing to avoid the pitfalls of excessive involution. The design especially aims to provide +language constructs that correspond intuitively to the normal expectations of users. + +Like many other human activities, the development of programs is becoming ever more decentralized and +distributed. Consequently, the ability to assemble a program from independently produced software +components continues to be a central idea in the design. The concepts of packages, of private types, and of +generic units are directly related to this idea, which has ramifications in many other aspects of the +language. An allied concern is the maintenance of programs to match changing requirements; type +extension and the hierarchical library enable a program to be modified while minimizing disturbance to +existing tested and trusted components. + +1 + +2 + +3/3 + +4/1 + +5/3 + +6/3 + +7 + +8 + +9 + +No language can avoid the problem of efficiency. Languages that require over-elaborate compilers, or that +lead to the inefficient use of storage or execution time, force these inefficiencies on all machines and on all + +10 + +xi 13 December 2012 + +Introduction + + Ada Reference Manual — 2012 Edition + +programs. Every construct of the language was examined in the light of present implementation +techniques. Any proposed construct whose implementation was unclear or that required excessive machine +resources was rejected. + +Language Summary + +An Ada program is composed of one or more program units. Program units may be subprograms (which +define executable algorithms), packages (which define collections of entities), task units (which define +concurrent computations), protected units (which define operations for the coordinated sharing of data +between tasks), or generic units (which define parameterized forms of packages and subprograms). Each +program unit normally consists of two parts: a specification, containing the information that must be +visible to other units, and a body, containing the implementation details, which need not be visible to other +units. Most program units can be compiled separately. + +This distinction of the specification and body, and the ability to compile units separately, allows a program +to be designed, written, and tested as a set of largely independent software components. + +An Ada program will normally make use of a library of program units of general utility. The language +provides means whereby individual organizations can construct their own libraries. All libraries are +structured in a hierarchical manner; this enables the logical decomposition of a subsystem into individual +components. The text of a separately compiled program unit must name the library units it requires. + +Program Units + +A subprogram is the basic unit for expressing an algorithm. There are two kinds of subprograms: +procedures and functions. A procedure is the means of invoking a series of actions. For example, it may +read data, update variables, or produce some output. It may have parameters, to provide a controlled +means of passing information between the procedure and the point of call. A function is the means of +invoking the computation of a value. It is similar to a procedure, but in addition will return a result. + +A package is the basic unit for defining a collection of logically related entities. For example, a package +can be used to define a set of type declarations and associated operations. Portions of a package can be +hidden from the user, thus allowing access only to the logical properties expressed by the package +specification. + +Subprogram and package units may be compiled separately and arranged in hierarchies of parent and child +units giving fine control over visibility of the logical properties and their detailed implementation. + +A task unit is the basic unit for defining a task whose sequence of actions may be executed concurrently +with those of other tasks. Such tasks may be implemented on multicomputers, multiprocessors, or with +interleaved execution on a single processor. A task unit may define either a single executing task or a task +type permitting the creation of any number of similar tasks. + +11 + +12 + +13 + +14 + +15 + +16 + +17 + +18 + +19/2 + +A protected unit is the basic unit for defining protected operations for the coordinated use of data shared +between tasks. Simple mutual exclusion is provided automatically, and more elaborate sharing protocols +can be defined. A protected operation can either be a subprogram or an entry. A protected entry specifies a +Boolean expression (an entry barrier) that must be True before the body of the entry is executed. A +protected unit may define a single protected object or a protected type permitting the creation of several +similar objects. + +Introduction + +13 December 2012 xii + + Ada Reference Manual — 2012 Edition + +Declarations and Statements + +The body of a program unit generally contains two parts: a declarative part, which defines the logical +entities to be used in the program unit, and a sequence of statements, which defines the execution of the +program unit. + +The declarative part associates names with declared entities. For example, a name may denote a type, a +constant, a variable, or an exception. A declarative part also introduces the names and parameters of other +nested subprograms, packages, task units, protected units, and generic units to be used in the program unit. + +The sequence of statements describes a sequence of actions that are to be performed. The statements are +executed in succession (unless a transfer of control causes execution to continue from another place). + +An assignment statement changes the value of a variable. A procedure call invokes execution of a +procedure after associating any actual parameters provided at the call with the corresponding formal +parameters. + +Case statements and if statements allow the selection of an enclosed sequence of statements based on the +value of an expression or on the value of a condition. + +The loop statement provides the basic iterative mechanism in the language. A loop statement specifies that +a sequence of statements is to be executed repeatedly as directed by an iteration scheme, or until an exit +statement is encountered. + +A block statement comprises a sequence of statements preceded by the declaration of local entities used by +the statements. + +Certain statements are associated with concurrent execution. A delay statement delays the execution of a +task for a specified duration or until a specified time. An entry call statement is written as a procedure call +statement; it requests an operation on a task or on a protected object, blocking the caller until the operation +can be performed. A called task may accept an entry call by executing a corresponding accept statement, +which specifies the actions then to be performed as part of the rendezvous with the calling task. An entry +call on a protected object is processed when the corresponding entry barrier evaluates to true, whereupon +the body of the entry is executed. The requeue statement permits the provision of a service as a number of +related activities with preference control. One form of the select statement allows a selective wait for one +of several alternative rendezvous. Other forms of the select statement allow conditional or timed entry +calls and the asynchronous transfer of control in response to some triggering event. + +Execution of a program unit may encounter error situations in which normal program execution cannot +continue. For example, an arithmetic computation may exceed the maximum allowed value of a number, +or an attempt may be made to access an array component by using an incorrect index value. To deal with +such error situations, the statements of a program unit can be textually followed by exception handlers that +specify the actions to be taken when the error situation arises. Exceptions can be raised explicitly by a +raise statement. + +Data Types + +Every object in the language has a type, which characterizes a set of values and a set of applicable +operations. The main classes of types are elementary types (comprising enumeration, numeric, and access +types) and composite types (including array and record types). + +20 + +21 + +22 + +23 + +24 + +25 + +26 + +27 + +28 + +29 + +30 + +31 + +An enumeration type defines an ordered set of distinct enumeration literals, for example a list of states or +an alphabet of characters. The enumeration +types Boolean, Character, Wide_Character, and +Wide_Wide_Character are predefined. + +32/2 + +xiii 13 December 2012 + +Introduction + + Ada Reference Manual — 2012 Edition + +33 + +34/2 + +35 + +36 + +37 + +38 + +Numeric types provide a means of performing exact or approximate numerical computations. Exact +computations use integer types, which denote sets of consecutive integers. Approximate computations use +either fixed point types, with absolute bounds on the error, or floating point types, with relative bounds on +the error. The numeric types Integer, Float, and Duration are predefined. + +Composite types allow definitions of structured objects with related components. The composite types in +the language include arrays and records. An array is an object with indexed components of the same type. +A record is an object with named components of possibly different types. Task and protected types are +also forms of composite types. The array types String, Wide_String, and Wide_Wide_String are +predefined. + +Record, task, and protected types may have special components called discriminants which parameterize +the type. Variant record structures that depend on the values of discriminants can be defined within a +record type. + +Access types allow the construction of linked data structures. A value of an access type represents a +reference to an object declared as aliased or to an object created by the evaluation of an allocator. Several +variables of an access type may designate the same object, and components of one object may designate +the same or other objects. Both the elements in such linked data structures and their relation to other +elements can be altered during program execution. Access types also permit references to subprograms to +be stored, passed as parameters, and ultimately dereferenced as part of an indirect call. + +Private types permit restricted views of a type. A private type can be defined in a package so that only the +logically necessary properties are made visible to the users of the type. The full structural details that are +externally irrelevant are then only available within the package and any child units. + +From any type a new type may be defined by derivation. A type, together with its derivatives (both direct +and indirect) form a derivation class. Class-wide operations may be defined that accept as a parameter an +operand of any type in a derivation class. For record and private types, the derivatives may be extensions +of the parent type. Types that support these object-oriented capabilities of class-wide operations and type +extension must be tagged, so that the specific type of an operand within a derivation class can be identified +at run time. When an operation of a tagged type is applied to an operand whose specific type is not known +until run time, implicit dispatching is performed based on the tag of the operand. + +38.1/2 + +Interface types provide abstract models from which other interfaces and types may be composed and +derived. This provides a reliable form of multiple inheritance. Interface types may also be implemented by +task types and protected types thereby enabling concurrent programming and inheritance to be merged. + +39 + +The concept of a type is further refined by the concept of a subtype, whereby a user can constrain the set +of allowed values of a type. Subtypes can be used to define subranges of scalar types, arrays with a limited +set of index values, and records and private types with particular discriminant values. + +40 + +Other Facilities + +41/2 + +Aspect clauses can be used to specify the mapping between types and features of an underlying machine. +For example, the user can specify that objects of a given type must be represented with a given number of +bits, or that the components of a record are to be represented using a given storage layout. Other features +allow the controlled use of low level, nonportable, or implementation-dependent aspects, including the +direct insertion of machine code. + +42/2 + +The predefined environment of the language provides for input-output and other capabilities by means of +standard library packages. Input-output is supported for values of user-defined as well as of predefined +types. Standard means of representing values in display form are also provided. + +Introduction + +13 December 2012 xiv + + Ada Reference Manual — 2012 Edition + +The predefined standard library packages provide facilities such as string manipulation, containers of +various kinds (vectors, lists, maps, etc.), mathematical functions, random number generation, and access to +the execution environment. + +The specialized annexes define further predefined library packages and facilities with emphasis on areas +such as real-time scheduling, interrupt handling, distributed systems, numerical computation, and high- +integrity systems. + +Finally, the language provides a powerful means of parameterization of program units, called generic +program units. The generic parameters can be types and subprograms (as well as objects and packages) +and so allow general algorithms and data structures to be defined that are applicable to all types of a given +class. + +Language Changes + +Paragraphs 44 through 57 have been removed as they described differences from the first edition of Ada (Ada 83). + +This International Standard replaces the second edition of 1995. It modifies the previous edition by +making changes and additions that improve the capability of the language and the reliability of programs +written in the language. This edition incorporates the changes from Amendment 1 (ISO/IEC +8652:1995:AMD 1:2007), which were designed to improve the portability of programs, interfacing to +other languages, and both the object-oriented and real-time capabilities. + +Significant changes originating in Amendment 1 are incorporated: + +• Support for program text is extended to cover the entire ISO/IEC 10646:2003 repertoire. +Execution support now includes the 32-bit character set. See subclauses 2.1, 3.5.2, 3.6.3, A.1, +A.3, and A.4. + +• The object-oriented model has been improved by the addition of an interface facility which +provides multiple inheritance and additional flexibility for type extensions. See subclauses 3.4, +3.9, and 7.3. An alternative notation for calling operations more akin to that used in other +languages has also been added. See subclause 4.1.3. + +• Access types have been further extended to unify properties such as the ability to access +constants and to exclude null values. See clause 3.10. Anonymous access types are now +permitted more freely and anonymous access-to-subprogram types are introduced. See +subclauses 3.3, 3.6, 3.10, and 8.5.1. + +• The control of structure and visibility has been enhanced to permit mutually dependent +references between units and finer control over access from the private part of a package. See +subclauses 3.10.1 and 10.1.2. In addition, limited types have been made more useful by the +provision of aggregates, constants, and constructor functions. See subclauses 4.3, 6.5, and 7.5. +• The predefined environment has been extended to include additional time and calendar +operations, improved string handling, a comprehensive container library, file and directory +management, and access to environment variables. See subclauses 9.6.1, A.4, A.16, A.17, and +A.18. + +• Two of the Specialized Needs Annexes have been considerably enhanced: + +• The Real-Time Systems Annex now includes the Ravenscar profile for high-integrity +systems, further dispatching policies such as Round Robin and Earliest Deadline First, +support for timing events, and support for control of CPU time utilization. See subclauses +D.2, D.13, D.14, and D.15. + +42.1/2 + +42.2/2 + +43 + +57.1/3 + +57.2/3 + +57.3/3 + +57.4/3 + +57.5/3 + +57.6/3 + +57.7/3 + +57.8/3 + +57.9/2 + +xv 13 December 2012 + +Introduction + + Ada Reference Manual — 2012 Edition + +57.10/3 + +57.11/3 + +57.12/3 + +• The Numerics Annex now includes support for real and complex vectors and matrices as +previously defined in ISO/IEC 13813:1997 plus further basic operations for linear algebra. +See subclause G.3. + +• The overall reliability of the language has been enhanced by a number of improvements. These +include new syntax which detects accidental overloading, as well as pragmas for making +assertions and giving better control over the suppression of checks. See subclauses 6.1, 11.4.2, +and 11.5. + +In addition, this third edition makes enhancements to address two important issues, namely, the particular +problems of multiprocessor architectures, and the need to further increase the capabilities regarding +assertions for correctness. It also makes additional changes and additions that improve the capability of the +language and the reliability of programs written in the language. + +57.13/3 + +The following significant changes with respect to the 1995 edition as amended by Amendment 1 are +incorporated: + +57.14/3 + +• New syntax (the aspect specification) is introduced to enable properties to be specified for + +various entities in a more structured manner than through pragmas. See subclause 13.1.1. + +57.15/3 + +57.16/3 + +57.17/3 + +57.18/3 + +57.19/3 + +57.20/3 + +• The concept of assertions introduced in the 2005 edition is extended with the ability to specify +preconditions and postconditions for subprograms, and invariants for private types. The concept +of constraints in defining subtypes is supplemented with subtype predicates that enable subsets +to be specified other than as simple ranges. These properties are all indicated using aspect +specifications. See subclauses 3.2.4, 6.1.1, and 7.3.2. + +• New forms of expressions are introduced. These are if expressions, case expressions, quantified +expressions, and expression functions. As well as being useful for programming in general by +avoiding the introduction of unnecessary assignments, they are especially valuable in conditions +and invariants since they avoid the need to introduce auxiliary functions. See subclauses 4.5.7, +4.5.8, and 6.8. Membership tests are also made more flexible. See subclauses 4.4 and 4.5.2. +• A number of changes are made to subprogram parameters. Functions may now have parameters +of all modes. In order to mitigate consequent (and indeed existing) problems of inadvertent order +dependence, rules are introduced to reduce aliasing. A parameter may now be explicitly marked +as aliased and the type of a parameter may be incomplete in certain circumstances. See +subclauses 3.10.1, 6.1, and 6.4.1. + +• The use of access types is now more flexible. The rules for accessibility and certain conversions +are improved. See subclauses 3.10.2, 4.5.2, 4.6, and 8.6. Furthermore, better control of storage +pools is provided. See subclause 13.11.4. + +• The Real-Time Systems Annex now includes facilities for defining domains of processors and +assigning tasks to them. Improvements are made to scheduling and budgeting facilities. See +subclauses D.10.1, D.14, and D.16. + +• A number of important improvements are made to the standard library. These include packages +for conversions between strings and UTF encodings, and classification functions for wide and +wide wide characters. Internationalization is catered for by a package giving locale information. +See subclauses A.3, A.4.11, and A.19. The container library is extended to include bounded +forms of the existing containers and new containers for indefinite objects, multiway trees, and +queues. See subclause A.18. + +57.21/3 + +• Finally, certain features are added primarily to ease the use of containers, such as the ability to +iterate over all elements in a container without having to encode the iteration. These can also be +used for iteration over arrays, and within quantified expressions. See subclauses 4.1.5, 4.1.6, +5.5.1, and 5.5.2. + +Introduction + +13 December 2012 xvi + + Ada Reference Manual — 2012 Edition + +Instructions for Comment Submission + +Informal comments on this International Standard may be sent via e-mail to ada-comment@ada- +auth.org. If appropriate, the Project Editor will initiate the defect correction procedure. + +Comments should use the following format: + +!topic Title summarizing comment +!reference Ada 2012 RMss.ss(pp) +!from Author Name yy-mm-dd +!keywords keywords related to topic +!discussion + +text of discussion + +where ss.ss is the clause or subclause number, pp is the paragraph number where applicable, and yy-mm-dd +is the date the comment was sent. The date is optional, as is the !keywords line. + +Please use a descriptive “Subject” in your e-mail message, and limit each message to a single comment. + +When correcting typographical errors or making minor wording suggestions, please put the correction +directly as the topic of the comment; use square brackets [ ] to indicate text to be omitted and curly braces +{ } to indicate text to be added, and provide enough context to make the nature of the suggestion self- +evident or put additional information in the body of the comment, for example: + +!topic [c]{C}haracter +!topic it[']s meaning is not defined + +Formal requests for interpretations and for reporting defects in this International Standard may be made in +accordance with the ISO/IEC JTC 1 Directives and the ISO/IEC JTC 1/SC 22 policy for interpretations. +National Bodies may submit a Defect Report to ISO/IEC JTC 1/SC 22 for resolution under the JTC 1 +procedures. A response will be provided and, if appropriate, a Technical Corrigendum will be issued in +accordance with the procedures. + +58/1 + +59 + +60/3 + +61/3 + +62/1 + +63 + +64 + +65 + +xvii 13 December 2012 + +Introduction + + + + + + + + + + + Ada Reference Manual — 2012 Edition + +Acknowledgements for the Ada 83 edition + +65.1/3 + +Ada is the result of a collective effort to design a common language for programming large scale and real- +time systems. + +65.2/3 + +65.3/3 + +65.4/3 + +65.5/3 + +65.6/3 + +65.7/3 + +65.8/3 + +65.9/3 + +The common high order language program began in 1974. The requirements of the United States +Department of Defense were formalized in a series of documents which were extensively reviewed by the +Services, industrial organizations, universities, and foreign military departments. The Ada language was +designed in accordance with the final (1978) form of these requirements, embodied in the Steelman +specification. + +The Ada design team was led by Jean D. Ichbiah and has included Bernd Krieg-Brueckner, Brian A. +Wichmann, Henry F. Ledgard, Jean-Claude Heliard, Jean-Loup Gailly, Jean-Raymond Abrial, John G.P. +Barnes, Mike Woodger, Olivier Roubine, Paul N. Hilfinger, and Robert Firth. + +At various stages of the project, several people closely associated with the design team made major +contributions. They include J.B. Goodenough, R.F. Brender, M.W. Davis, G. Ferran, K. Lester, L. +MacLaren, E. Morel, I.R. Nassi, I.C. Pyle, S.A. Schuman, and S.C. Vestal. + +Two parallel efforts that were started in the second phase of this design had a deep influence on the +language. One was the development of a formal definition using denotational semantics, with the +participation of V. Donzeau-Gouge, G. Kahn, and B. Lang. The other was the design of a test translator +with the participation of K. Ripken, P. Boullier, P. Cadiou, J. Holden, J.F. Hueras, R.G. Lange, and D.T. +Cornhill. The entire effort benefitted from the dedicated assistance of Lyn Churchill and Marion Myers, +and the effective technical support of B. Gravem, W.L. Heimerdinger, and P. Cleve. H.G. Schmitz served +as program manager. + +Over the five years spent on this project, several intense week-long design reviews were conducted, with +the participation of P. Belmont, B. Brosgol, P. Cohen, R. Dewar, A. Evans, G. Fisher, H. Harte, A.L. +Hisgen, P. Knueven, M. Kronental, N. Lomuto, E. Ploedereder, G. Seegmueller, V. Stenning, D. Taffs, +and also F. Belz, R. Converse, K. Correll, A.N. Habermann, J. Sammet, S. Squires, J. Teller, P. Wegner, +and P.R. Wetherall. + +Several persons had a constructive influence with their comments, criticisms and suggestions. They +include P. Brinch Hansen, G. Goos, C.A.R. Hoare, Mark Rain, W.A. Wulf, and also E. Boebert, P. +Bonnard, H. Clausen, M. Cox, G. Dismukes, R. Eachus, T. Froggatt, H. Ganzinger, C. Hewitt, S. Kamin, +R. Kotler, O. Lecarme, J.A.N. Lee, J.L. Mansion, F. Minel, T. Phinney, J. Roehrich, V. Schneider, A. +Singer, D. Slosberg, I.C. Wand, the reviewers of Ada-Europe, AdaTech, Afcet, those of the LMSC review +team, and those of the Ada Tokyo Study Group. + +These reviews and comments, the numerous evaluation reports received at the end of the first and second +phase, the nine hundred language issue reports and test and evaluation reports received from fifteen +different countries during the third phase of the project, the thousands of comments received during the +ANSI Canvass, and the on-going work of the IFIP Working Group 2.4 on system implementation +languages and that of the Purdue Europe LTPL-E committee, all had a substantial influence on the final +definition of Ada. + +The Military Departments and Agencies have provided a broad base of support including funding, +extensive reviews, and countless individual contributions by the members of the High Order Language +Working Group and other interested personnel. In particular, William A. Whitaker provided leadership for +the program during the formative stages. David A. Fisher was responsible for the successful development +and refinement of the language requirement documents that led to the Steelman specification. + +Introduction + +13 December 2012 xviii + + Ada Reference Manual — 2012 Edition + +The Ada 83 language definition was developed by Cii Honeywell Bull and later Alsys, and by Honeywell +Systems and Research Center, under contract to the United States Department of Defense. William E. +Carlson and later Larry E. Druffel served as the technical representatives of the United States Government +and effectively coordinated the efforts of all participants in the Ada program. + +65.10/3 + +Acknowledgements for the Ada 95 edition + +This International Standard was prepared by the Ada 9X Mapping/Revision Team based at Intermetrics, +Inc., which has included: W. Carlson, Program Manager; T. Taft, Technical Director; J. Barnes +(consultant); B. Brosgol (consultant); R. Duff (Oak Tree Software); M. Edwards; C. Garrity; R. Hilliard; +O. Pazy (consultant); D. Rosenfeld; L. Shafer; W. White; M. Woodger. + +The following consultants to the Ada 9X Project contributed to the Specialized Needs Annexes: T. Baker +(Real-Time/Systems Programming — SEI, FSU); K. Dritz (Numerics — Argonne National Laboratory); +A. Gargaro (Distributed Systems — Computer Sciences); J. Goodenough (Real-Time/Systems +Programming — SEI); J. McHugh (Secure Systems — consultant); B. Wichmann (Safety-Critical Systems +— NPL: UK). + +This work was regularly reviewed by the Ada 9X Distinguished Reviewers and the members of the Ada +9X Rapporteur Group (XRG): E. Ploedereder, Chairman of DRs and XRG (University of Stuttgart: +Germany); B. Bardin (Hughes); J. Barnes (consultant: UK); B. Brett (DEC); B. Brosgol (consultant); R. +Brukardt (RR Software); N. Cohen (IBM); R. Dewar (NYU); G. Dismukes (TeleSoft); A. Evans +(consultant); A. Gargaro (Computer Sciences); M. Gerhardt (ESL); J. Goodenough (SEI); S. Heilbrunner +(University of Salzburg: Austria); P. Hilfinger (UC/Berkeley); B. Källberg (CelsiusTech: Sweden); M. +Kamrad II (Unisys); J. van Katwijk (Delft University of Technology: The Netherlands); V. Kaufman +(Russia); P. Kruchten (Rational); R. Landwehr (CCI: Germany); C. Lester (Portsmouth Polytechnic: UK); +L. Månsson (TELIA Research: Sweden); S. Michell (Multiprocessor Toolsmiths: Canada); M. Mills (US +Air Force); D. Pogge (US Navy); K. Power (Boeing); O. Roubine (Verdix: France); A. Strohmeier (Swiss +Fed Inst of Technology: Switzerland); W. Taylor (consultant: UK); J. Tokar (Tartan); E. Vasilescu +(Grumman); J. Vladik (Prospeks s.r.o.: Czech Republic); S. Van Vlierberghe (OFFIS: Belgium). + +Other valuable feedback influencing the revision process was provided by the Ada 9X Language Precision +Team (Odyssey Research Associates), the Ada 9X User/Implementer Teams (AETECH, Tartan, TeleSoft), +the Ada 9X Implementation Analysis Team (New York University) and the Ada community-at-large. + +Special thanks go to R. Mathis, Convenor of ISO/IEC JTC 1/SC 22 Working Group 9. + +The Ada 9X Project was sponsored by the Ada Joint Program Office. Christine M. Anderson at the Air +Force Phillips Laboratory (Kirtland AFB, NM) was the project manager. + +66 + +67 + +68 + +69 + +70 + +71 + +Acknowledgements for the Corrigendum version + +The editor [R. Brukardt (USA)] would like to thank the many people whose hard work and assistance has +made this update possible. + +71.1/3 + +Thanks go out to all of the members of the ISO/IEC JTC 1/SC 22/WG 9 Ada Rapporteur Group, whose +work on creating and editing the wording corrections was critical to the entire process. Especially valuable +contributions came from the chairman of the ARG, E. Ploedereder (Germany), who kept the process +moving; J. Barnes (UK) and K. Ishihata (Japan), whose extremely detailed reviews kept the editor on his +toes; G. Dismukes (USA), M. Kamrad (USA), P. Leroy (France), S. Michell (Canada), T. Taft (USA), J. +Tokar (USA), and other members too numerous to mention. + +71.2/1 + +xix 13 December 2012 + +Introduction + + Ada Reference Manual — 2012 Edition + +71.3/1 + +Special thanks go to R. Duff (USA) for his explanations of the previous system of formatting of these +documents during the tedious conversion to more modern formats. Special thanks also go to the convenor +of ISO/IEC JTC 1/SC 22/WG 9, J. Moore (USA), without whose help and support the Corrigendum and +this consolidated reference manual would not have been possible. + +Acknowledgements for the Amendment 1 version + +71.4/3 + +The editor [R. Brukardt (USA)] would like to thank the many people whose hard work and assistance has +made this update possible. + +71.5/2 + +Thanks go out to all of the members of the ISO/IEC JTC 1/SC 22/WG 9 Ada Rapporteur Group, whose +work on creating and editing the wording corrections was critical to the entire process. Especially valuable +contributions came from the chairman of the ARG, P. Leroy (France), who kept the process on schedule; J. +Barnes (UK) whose careful reviews found many typographical errors; T. Taft (USA), who always seemed +to have a suggestion when we were stuck, and who also was usually able to provide the valuable service of +explaining why things were as they are; S. Baird (USA), who found many obscure problems with the +proposals; and A. Burns (UK), who pushed many of the real-time proposals to completion. Other ARG +members who contributed were: R. Dewar (USA), G. Dismukes (USA), R. Duff (USA), K. Ishihata +(Japan), S. Michell (Canada), E. Ploedereder (Germany), J.P. Rosen (France), E. Schonberg (USA), J. +Tokar (USA), and T. Vardanega (Italy). + +71.6/2 + +Special thanks go to Ada-Europe and the Ada Resource Association, without whose help and support the +Amendment and this consolidated reference manual would not have been possible. M. Heaney (USA) +requires special thanks for his tireless work on the containers packages. Finally, special thanks go to the +convenor of ISO/IEC JTC 1/SC 22/WG 9, J. Moore (USA), who guided the document through the +standardization process. + +Acknowledgements for the Ada 2012 edition + +71.7/3 + +The editor [R. Brukardt (USA)] would like to thank the many people whose hard work and assistance has +made this revision possible. + +71.8/3 + +Thanks go out to all of the members of the ISO/IEC JTC 1/SC 22/WG 9 Ada Rapporteur Group, whose +work on creating and editing the wording changes was critical to the entire process. Especially valuable +contributions came from the chairman of the ARG, E. Schonberg (USA), who guided the work; T. Taft +(USA), whose insights broke many logjams, both in design and wording; J. Barnes (UK) whose careful +reviews uncovered many editorial errors; S. Baird (USA), who repeatedly found obscure interactions with +the proposals that the rest of us missed. Other ARG members who substantially contributed were: A. +Burns (UK), J. Cousins (UK), R. Dewar (USA), G. Dismukes (USA), R. Duff (USA), P. Leroy (France), +B. Moore (Canada), E. Ploedereder (Germany), J.P. Rosen (France), B. Thomas (USA), and T. Vardanega +(Italy). + +71.9/3 + +Special thanks go to Ada-Europe and the Ada Resource Association, without whose help and support this +third edition of the Ada Standard would not have been possible. A special mention has to go to A. +Beneschan (USA) for his efforts in eliminating sloppiness in our wording. M. Heaney (USA) also deserves +a mention for his efforts to improve the containers packages. Finally, special thanks go to the convenor of +ISO/IEC JTC 1/SC 22/WG 9, J. Tokar (USA), who guided the document through the standardization +process. + +Introduction + +13 December 2012 xx + + Ada Reference Manual — 2012 Edition + +Changes + +The International Standard is the same as this version of the Reference Manual, except: + +• This list of Changes is not included in the International Standard. +• The “Acknowledgements” page is not included in the International Standard. +• The text in the running headers and footers on each page is slightly different in the International + +Standard. + +• The title page(s) are different in the International Standard. +• This document is formatted for 8.5-by-11-inch paper, whereas the International Standard is + +formatted for A4 paper (210-by-297mm); thus, the page breaks are in different places. + +• This paragraph was deleted. +• The “Using this version of the Ada Reference Manual” subclause is not included in the + +International Standard. + +• Paragraph numbers are not included in the International Standard. + +Using this version of the Ada Reference Manual + +This document has been revised with the corrections specified in Technical Corrigendum 1 (ISO/IEC +8652:1995/COR.1:2001) and Amendment 1 (ISO/IEC 8652/AMD 1:2007), along with changes +specifically for this third edition. In addition, a variety of editorial errors have been corrected. + +Changes to the original 8652:1995 can be identified by the version number following the paragraph +number. Paragraphs with a version number of /1 were changed by Technical Corrigendum 1 or were +editorial corrections at that time, while paragraphs with a version number of /2 were changed by +Amendment 1 or were more recent editorial corrections, and paragraphs with a version number of /3 were +changed by the third (2012) edition of the Standard or were still more recent editorial corrections. +Paragraphs not so marked are unchanged by the third edition, Amendment 1, Technical Corrigendum 1, or +editorial corrections. Paragraph numbers of unchanged paragraphs are the same as in the 1995 edition of +the Ada Reference Manual. In addition, some versions of this document include revision bars near the +paragraph numbers. Where paragraphs are inserted, the paragraph numbers are of the form pp.nn, where +pp is the number of the preceding paragraph, and nn is an insertion number. For instance, the first +paragraph inserted after paragraph 8 is numbered 8.1, the second paragraph inserted is numbered 8.2, and +so on. Deleted paragraphs are indicated by the text This paragraph was deleted. Deleted paragraphs include +empty paragraphs that were numbered in the 1995 edition of the Ada Reference Manual. + +72 + +73 + +74 + +75 + +76 + +77 + +77.1/3 + +77.2/3 + +77.3/3 + +77.4/3 + +77.5/3 + +xxi 13 December 2012 + +Introduction + + Ada Reference Manual — 2012 Edition + +1 General + +1.1 Scope + +This International Standard specifies the form and meaning of programs written in Ada. Its purpose is to +promote the portability of Ada programs to a variety of computing systems. + +Ada is a programming language designed to support the construction of long-lived, highly reliable +software systems. The language includes facilities to define packages of related types, objects, and +operations. The packages may be parameterized and the types may be extended to support the construction +of libraries of reusable, adaptable software components. The operations may be implemented as +subprograms using conventional sequential control structures, or as entries that include synchronization of +concurrent threads of control as part of their invocation. Ada supports object-oriented programming by +providing classes and interfaces, inheritance, polymorphism of variables and methods, and generic units. +The language treats modularity in the physical sense as well, with a facility to support separate +compilation. + +The language provides rich support for real-time, concurrent programming, and includes facilities for +multicore and multiprocessor programming. Errors can be signaled as exceptions and handled explicitly. +The language also covers systems programming; this requires precise control over the representation of +data and access to system-dependent properties. Finally, a predefined environment of standard packages is +provided, including facilities for, among others, input-output, string manipulation, numeric elementary +functions, and random number generation, and definition and use of containers. + +1.1.1 Extent + +This International Standard specifies: + +• The form of a program written in Ada; +• The effect of translating and executing such a program; +• The manner in which program units may be combined to form Ada programs; +• The language-defined library units that a conforming implementation is required to supply; +• The permissible variations within the standard, and the manner in which they are to be + +documented; + +• Those violations of the standard that a conforming implementation is required to detect, and the + +effect of attempting to translate or execute a program containing such violations; + +• Those violations of the standard that a conforming implementation is not required to detect. + +This International Standard does not specify: + +• The means whereby a program written in Ada is transformed into object code executable by a + +processor; + +• The means whereby translation or execution of programs is invoked and the executing units are + +controlled; + +1/3 + +2/3 + +3/3 + +1 + +2 + +3 + +4 + +5 + +6 + +7 + +8 + +9 + +10 + +11 + +1 13 December 2012 + +1 General + + + Ada Reference Manual — 2012 Edition + +• The size or speed of the object code, or the relative execution speed of different language + +constructs; + +• The form or contents of any listings produced by implementations; in particular, the form or + +contents of error or warning messages; + +• The effect of unspecified execution. +• The size of a program or program unit that will exceed the capacity of a particular conforming + +implementation. + +1.1.2 Structure + +This International Standard contains thirteen clauses, fifteen annexes, and an index. + +The core of the Ada language consists of: + +• Clauses 1 through 13 +• Annex A, “Predefined Language Environment” +• Annex B, “Interface to Other Languages” +• Annex J, “Obsolescent Features” + +The following Specialized Needs Annexes define features that are needed by certain application areas: + +• Annex C, “Systems Programming” +• Annex D, “Real-Time Systems” +• Annex E, “Distributed Systems” +• Annex F, “Information Systems” +• Annex G, “Numerics” +• Annex H, “High Integrity Systems” + +The core language and the Specialized Needs Annexes are normative, except that the material in each of +the items listed below is informative: + +• Text under a NOTES or Examples heading. +• Each subclause whose title starts with the word “Example” or “Examples”. + +All implementations shall conform to the core language. In addition, an implementation may conform +separately to one or more Specialized Needs Annexes. + +The following Annexes are informative: + +• Annex K, “Language-Defined Aspects and Attributes” +• Annex L, “Language-Defined Pragmas” +• Annex M, “Summary of Documentation Requirements” +• Annex N, “Glossary” +• Annex P, “Syntax Summary” +• Annex Q, “Language-Defined Entities” + +12 + +13 + +14 + +15 + +1/3 + +2 + +3/3 + +4 + +5 + +6 + +7 + +8 + +9 + +10 + +11 + +12 + +13 + +14 + +15 + +16/3 + +17 + +18 + +19 + +20 + +21/3 + +22 + +23 + +23.1/3 + +1.1.1 Extent + +13 December 2012 2 + + Each section is divided into subclauses that have a common structure. Each clause and subclause first +introduces its subject. After the introductory text, text is labeled with the following headings: + +24/3 + +Ada Reference Manual — 2012 Edition + +Syntax rules (indented). + +Syntax + +Name Resolution Rules + +Compile-time rules that are used in name resolution, including overload resolution. + +Rules that are enforced at compile time. A construct is legal if it obeys all of the Legality Rules. + +Legality Rules + +A definition of the compile-time effect of each construct. + +Static Semantics + +Post-Compilation Rules + +Rules that are enforced before running a partition. A partition is legal if its compilation units are legal and +it obeys all of the Post-Compilation Rules. + +A definition of the run-time effect of each construct. + +Dynamic Semantics + +Situations that result in bounded (run-time) errors (see 1.1.5). + +Bounded (Run-Time) Errors + +Situations that result in erroneous execution (see 1.1.5). + +Erroneous Execution + +Additional requirements for conforming implementations. + +Implementation Requirements + +Documentation requirements for conforming implementations. + +Documentation Requirements + +Metrics that are specified for the time/space properties of the execution of certain language constructs. + +Metrics + +Additional permissions given to the implementer. + +Implementation Permissions + +Implementation Advice + +Optional advice given to the implementer. The word “should” is used to indicate that the advice is a +recommendation, not a requirement. It is implementation defined whether or not a given recommendation +is obeyed. + +NOTES +1 Notes emphasize consequences of the rules described in the (sub)clause or elsewhere. This material is informative. + +Examples illustrate the possible forms of the constructs described. This material is informative. + +Examples + +3 13 December 2012 + +Structure 1.1.2 + +25 + +26/3 + +27 + +28 + +29 + +30 + +31 + +32 + +33 + +34 + +35 + +36 + +37 + +38 + +39 + + Ada Reference Manual — 2012 Edition + +1 + +2 + +3 + +4 + +5 + +6 + +7 + +8 + +9 + +10 + +11 + +12 + +13 + +14 + +15 + +16 + +1.1.3 Conformity of an Implementation with the Standard + +A conforming implementation shall: + +Implementation Requirements + +• Translate and correctly execute legal programs written in Ada, provided that they are not so + +large as to exceed the capacity of the implementation; + +• Identify all programs or program units that are so large as to exceed the capacity of the + +implementation (or raise an appropriate exception at run time); + +• Identify all programs or program units that contain errors whose detection is required by this + +International Standard; + +• Supply all language-defined library units required by this International Standard; +• Contain no variations except those explicitly permitted by this International Standard, or those +that are impossible or impractical to avoid given the implementation's execution environment; + +• Specify all such variations in the manner prescribed by this International Standard. + +The external effect of the execution of an Ada program is defined in terms of its interactions with its +external environment. The following are defined as external interactions: + +• Any interaction with an external file (see A.7); +• The execution of certain code_statements (see 13.8); which code_statements cause external + +interactions is implementation defined. + +• Any call on an imported subprogram (see Annex B), including any parameters passed to it; +• Any result returned or exception propagated from a main subprogram (see 10.2) or an exported + +subprogram (see Annex B) to an external caller; + +• Any read or update of an atomic or volatile object (see C.6); +• The values of imported and exported objects (see Annex B) at the time of any other interaction + +with the external environment. + +A conforming implementation of this International Standard shall produce for the execution of a given +Ada program a set of interactions with the external environment whose order and timing are consistent +with the definitions and requirements of this International Standard for the semantics of the given program. + +An implementation that conforms to this Standard shall support each capability required by the core +language as specified. In addition, an implementation that conforms to this Standard may conform to one +or more Specialized Needs Annexes (or to none). Conformance to a Specialized Needs Annex means that +each capability required by the Annex is provided as specified. + +17/3 + +An implementation conforming to this International Standard may provide additional aspects, attributes, +library units, and pragmas. However, it shall not provide any aspect, attribute, library unit, or pragma +having the same name as an aspect, attribute, library unit, or pragma (respectively) specified in a +Specialized Needs Annex unless the provided construct is either as specified in the Specialized Needs +Annex or is more limited in capability than that required by the Annex. A program that attempts to use an +unsupported capability of an Annex shall either be identified by the implementation before run time or +shall raise an exception at run time. + +1.1.3 Conformity of an Implementation with the Standard + +13 December 2012 4 + + Ada Reference Manual — 2012 Edition + +Documentation Requirements + +Certain aspects of the semantics are defined to be either implementation defined or unspecified. In such +cases, the set of possible effects is specified, and the implementation may choose any effect in the set. +Implementations shall document their behavior in implementation-defined situations, but documentation is +not required for unspecified situations. The implementation-defined characteristics are summarized in M.2. + +The implementation may choose to document implementation-defined behavior either by documenting +what happens in general, or by providing some mechanism for the user to determine what happens in a +particular case. + +Implementation Advice + +If an implementation detects the use of an unsupported Specialized Needs Annex feature at run time, it +should raise Program_Error if feasible. + +If an implementation wishes to provide implementation-defined extensions to the functionality of a +language-defined library unit, it should normally do so by adding children to the library unit. + +NOTES +2 The above requirements imply that an implementation conforming to this Standard may support some of the capabilities +required by a Specialized Needs Annex without supporting all required capabilities. + +1.1.4 Method of Description and Syntax Notation + +The form of an Ada program is described by means of a context-free syntax together with context- +dependent requirements expressed by narrative rules. + +The meaning of Ada programs is described by means of narrative rules defining both the effects of each +construct and the composition rules for constructs. + +The context-free syntax of the language is described using a simple variant of Backus-Naur Form. In +particular: + +• Lower case words in a sans-serif font, some containing embedded underlines, are used to denote + +syntactic categories, for example: + +case_statement + +• Boldface words are used to denote reserved words, for example: + +array + +• Square brackets enclose optional items. Thus the two following rules are equivalent. + +simple_return_statement ::= return [expression]; +simple_return_statement ::= return; | return expression; + +• Curly brackets enclose a repeated item. The item may appear zero or more times; the repetitions +occur from left to right as with an equivalent left-recursive rule. Thus the two following rules are +equivalent. + +term ::= factor {multiplying_operator factor} +term ::= factor | term multiplying_operator factor + +• A vertical line separates alternative items unless it occurs immediately after an opening curly + +bracket, in which case it stands for itself: + +constraint ::= scalar_constraint | composite_constraint +discrete_choice_list ::= discrete_choice {| discrete_choice} + +18 + +19 + +20 + +21 + +22 + +1 + +2 + +3 + +4 + +5 + +6 + +7 + +8 + +9/2 + +10 + +11 + +12 + +13 + +5 13 December 2012 + +Conformity of an Implementation with the Standard 1.1.3 + + Ada Reference Manual — 2012 Edition + +14 + +14.1/3 + +• If the name of any syntactic category starts with an italicized part, it is equivalent to the category +name without the italicized part. The italicized part is intended to convey some semantic +information. For example subtype_name and task_name are both equivalent to name alone. + +The delimiters, compound delimiters, reserved words, and numeric_literals are exclusively made of the +characters whose code point is between 16#20# and 16#7E#, inclusively. The special characters for which +names are defined in this International Standard (see 2.1) belong to the same range. For example, the +character E in the definition of exponent is the character whose name is “LATIN CAPITAL LETTER E”, +not “GREEK CAPITAL LETTER EPSILON”. + +14.2/3 + +When this International Standard mentions the conversion of some character or sequence of characters to +upper case, it means the character or sequence of characters obtained by using simple upper case mapping, +as defined by documents referenced in the note in Clause 1 of ISO/IEC 10646:2011. + +15 + +16 + +17 + +18 + +19 + +20 + +21 + +1 + +2 + +3 + +A syntactic category is a nonterminal in the grammar defined in BNF under “Syntax.” Names of syntactic +categories are set in a different font, like_this. + +A construct is a piece of text (explicit or implicit) that is an instance of a syntactic category defined under +“Syntax”. + +A constituent of a construct is the construct itself, or any construct appearing within it. + +Whenever the run-time semantics defines certain actions to happen in an arbitrary order, this means that +the implementation shall arrange for these actions to occur in a way that is equivalent to some sequential +order, following the rules that result from that sequential order. When evaluations are defined to happen in +an arbitrary order, with conversion of the results to some subtypes, or with some run-time checks, the +evaluations, conversions, and checks may be arbitrarily interspersed, so long as each expression is +evaluated before converting or checking its value. Note that the effect of a program can depend on the +order chosen by the implementation. This can happen, for example, if two actual parameters of a given call +have side effects. + +NOTES +3 The syntax rules describing structured constructs are presented in a form that corresponds to the recommended +paragraphing. For example, an if_statement is defined as: + +if_statement ::= + if condition then + sequence_of_statements + {elsif condition then + sequence_of_statements} + [else + sequence_of_statements] + end if; + +4 The line breaks and indentation in the syntax rules indicate the recommended line breaks and indentation in the +corresponding constructs. The preferred places for other line breaks are after semicolons. + +1.1.5 Classification of Errors + +Implementation Requirements + +The language definition classifies errors into several different categories: + +• Errors that are required to be detected prior to run time by every Ada implementation; + + These errors correspond to any violation of a rule given in this International Standard, other than +those listed below. In particular, violation of any rule that uses the terms shall, allowed, +permitted, legal, or illegal belongs to this category. Any program that contains such an error is + +1.1.4 Method of Description and Syntax Notation + +13 December 2012 6 + + Ada Reference Manual — 2012 Edition + +not a legal Ada program; on the other hand, the fact that a program is legal does not mean, per +se, that the program is free from other forms of error. + + The rules are further classified as either compile time rules, or post compilation rules, depending +on whether a violation has to be detected at the time a compilation unit is submitted to the +compiler, or may be postponed until the time a compilation unit is incorporated into a partition +of a program. + +• Errors that are required to be detected at run time by the execution of an Ada program; + + The corresponding error situations are associated with the names of the predefined exceptions. +Every Ada compiler is required to generate code that raises the corresponding exception if such +an error situation arises during program execution. If such an error situation is certain to arise in +every execution of a construct, then an implementation is allowed (although not required) to +report this fact at compilation time. + +• Bounded errors; + + The language rules define certain kinds of errors that need not be detected either prior to or +during run time, but if not detected, the range of possible effects shall be bounded. The errors of +this category are called bounded errors. The possible effects of a given bounded error are +specified for each such error, but in any case one possible effect of a bounded error is the raising +of the exception Program_Error. + +• Erroneous execution. + +In addition to bounded errors, the language rules define certain kinds of errors as leading to +erroneous execution. Like bounded errors, the implementation need not detect such errors either +prior to or during run time. Unlike bounded errors, there is no language-specified bound on the +possible effect of erroneous execution; the effect is in general not predictable. + +Implementation Permissions + +An implementation may provide nonstandard modes of operation. Typically these modes would be +selected by a pragma or by a command line switch when the compiler is invoked. When operating in a +nonstandard mode, the implementation may reject compilation_units that do not conform to additional +requirements associated with the mode, such as an excessive number of warnings or violation of coding +style guidelines. Similarly, in a nonstandard mode, the implementation may apply special optimizations or +alternative algorithms that are only meaningful for programs that satisfy certain criteria specified by the +implementation. In any case, an implementation shall support a standard mode that conforms to the +requirements of this International Standard; in particular, in the standard mode, all legal compilation_units +shall be accepted. + +4 + +5 + +6 + +7 + +8 + +9 + +10 + +11 + +If an implementation detects a bounded error or erroneous execution, it should raise Program_Error. + +12 + +Implementation Advice + +1.2 Normative References + +The following documents, in whole or in part, are normatively referenced in this document and are +indispensable for its application. For dated references, only the edition cited applies. For undated +references, the latest edition of the referenced document (including any amendments) applies. + +1/3 + +ISO 639-3:2007, Codes for the representation of names of languages — Part 3: Alpha-3 code for +comprehensive coverage of languages. + +1.1/3 + +ISO/IEC 646:1991, Information technology — ISO 7-bit coded character set for information interchange. + +2 + +7 13 December 2012 + +Classification of Errors 1.1.5 + + + Ada Reference Manual — 2012 Edition + +3/2 + +ISO/IEC 1539-1:2004, Information technology — Programming languages — Fortran — Part 1: Base +language. + +4/2 + +ISO/IEC 1989:2002, Information technology — Programming languages — COBOL. + +4.1/3 + +ISO/IEC 3166-1:2006, Codes for the representation of names of countries and their subdivisions — Part +1: Country Codes. + +5 + +ISO/IEC 6429:1992, Information technology — Control functions for coded graphic character sets. + +5.1/2 + +ISO 8601:2004, Data elements and interchange formats — Information interchange — Representation of +dates and times. + +6/3 + +7/3 + +8/3 + +9/3 + +10/2 + +1/2 + +ISO/IEC 8859-1:1998, Information technology — 8-bit single-byte coded graphic character sets — Part 1: +Latin alphabet No. 1. + +ISO/IEC 9899:2011, Information technology — Programming languages — C. + +ISO/IEC 10646:2011, Information technology — Universal Multiple-Octet Coded Character Set (UCS). + +ISO/IEC 14882:2011, Information technology — Programming languages — C++. + +ISO/IEC TR 19769:2004, Information technology — Programming languages, their environments and +system software interfaces — Extensions for the programming language C to support new character data +types. + +1.3 Terms and Definitions + +Terms are defined throughout this International Standard, indicated by italic type. Terms explicitly defined +in this International Standard are not to be presumed to refer implicitly to similar terms defined elsewhere. +Mathematical terms not defined in this International Standard are to be interpreted according to the CRC +Concise Encyclopedia of Mathematics, Second Edition. Other terms not defined in this International +Standard are to be interpreted according to the Webster's Third New International Dictionary of the +English Language. Informal descriptions of some terms are also given in Annex N, “Glossary”. + +1.2 Normative References + +13 December 2012 8 + + Ada Reference Manual — 2012 Edition + +2 Lexical Elements + +The text of a program consists of the texts of one or more compilations. The text of a compilation is a +sequence of lexical elements, each composed of characters; the rules of composition are given in this +clause. Pragmas, which provide certain information for the compiler, are also described in this clause. + +1/3 + +2.1 Character Set + +The character repertoire for the text of an Ada program consists of the entire coding space described by the +ISO/IEC 10646:2011 Universal Multiple-Octet Coded Character Set. This coding space is organized in +planes, each plane comprising 65536 characters. + +1/3 + +Paragraphs 2 and 3 were deleted. + +Syntax + +A character is defined by this International Standard for each cell in the coding space described by +ISO/IEC 10646:2011, regardless of whether or not ISO/IEC 10646:2011 allocates a character to that +cell. + +Static Semantics + +The coded representation for characters is implementation defined (it need not be a representation defined +within ISO/IEC 10646:2011). A character whose relative code point in its plane is 16#FFFE# or +16#FFFF# is not allowed anywhere in the text of a program. The only characters allowed outside of +comments are those in categories other_format, format_effector, and graphic_character. + +The semantics of an Ada program whose text is not in Normalization Form KC (as defined by Clause 21 +of ISO/IEC 10646:2011) is implementation defined. + +The description of the language definition in this International Standard uses the character properties +General Category, Simple Uppercase Mapping, Uppercase Mapping, and Special Case Condition of the +documents referenced by the note in Clause 1 of ISO/IEC 10646:2011. The actual set of graphic symbols +used by an implementation for the visual representation of the text of an Ada program is not specified. + +Characters are categorized as follows: + +This paragraph was deleted. + +letter_uppercase + +Any character whose General Category is defined to be “Letter, Uppercase”. + +letter_lowercase + +Any character whose General Category is defined to be “Letter, Lowercase”. + +letter_titlecase + +Any character whose General Category is defined to be “Letter, Titlecase”. + +letter_modifier + +Any character whose General Category is defined to be “Letter, Modifier”. + +letter_other + +Any character whose General Category is defined to be “Letter, Other”. + +mark_non_spacing + +Any character whose General Category is defined to be “Mark, Non-Spacing”. + +mark_spacing_combining + +Any character whose General Category is defined to be “Mark, Spacing Combining”. + +3.1/3 + +4/3 + +4.1/3 + +5/3 + +6/3 + +7/2 + +8/2 + +9/2 + +9.1/2 + +9.2/2 + +9.3/2 + +9.4/2 + +9.5/2 + +9 13 December 2012 + +Lexical Elements 2 + + + + + + + + + + Ada Reference Manual — 2012 Edition + +10/2 + +number_decimal + +Any character whose General Category is defined to be “Number, Decimal”. + +10.1/2 + +number_letter + +Any character whose General Category is defined to be “Number, Letter”. + +10.2/2 + +punctuation_connector + +Any character whose General Category is defined to be “Punctuation, Connector”. + +10.3/2 + +other_format + +Any character whose General Category is defined to be “Other, Format”. + +11/2 + +separator_space + +Any character whose General Category is defined to be “Separator, Space”. + +12/2 + +separator_line + +Any character whose General Category is defined to be “Separator, Line”. + +12.1/2 + +separator_paragraph + +Any character whose General Category is defined to be “Separator, Paragraph”. + +13/3 + +format_effector + +The characters whose code points are 16#09# (CHARACTER TABULATION), 16#0A# +(LINE FEED), 16#0B# (LINE TABULATION), 16#0C# (FORM FEED), 16#0D# +(CARRIAGE RETURN), 16#85# (NEXT LINE), and the characters in categories +separator_line and separator_paragraph. + +13.1/2 + +other_control + +Any character whose General Category is defined to be “Other, Control”, and which is not +defined to be a format_effector. + +13.2/2 + +other_private_use + +Any character whose General Category is defined to be “Other, Private Use”. + +13.3/2 + +other_surrogate + +Any character whose General Category is defined to be “Other, Surrogate”. + +14/3 + +graphic_character + +the categories other_control, other_private_use, +Any character +other_surrogate, format_effector, and whose relative code point in its plane is neither +16#FFFE# nor 16#FFFF#. + +is not + +that + +in + +15/3 + +The following names are used when referring to certain characters (the first name is that given in ISO/IEC +10646:2011): + + graphic symbol + +name + + graphic symbol + +name + + " + # + & + ' + ( + ) + * + + + , + – + . + +quotation mark +number sign +ampersand +apostrophe, tick +left parenthesis +right parenthesis +asterisk, multiply +plus sign +comma +hyphen-minus, minus +full stop, dot, point + + : + ; + < + = + > + _ + | + / + ! + % + +colon +semicolon +less-than sign +equals sign +greater-than sign +low line, underline +vertical line +solidus, divide +exclamation point +percent sign + +2.1 Character Set + +13 December 2012 10 + + + + + + + + + + + + + + + + Ada Reference Manual — 2012 Edition + +Implementation Requirements + +An Ada implementation shall accept Ada source code in UTF-8 encoding, with or without a BOM (see +A.4.11), where every character is represented by its code point. The character pair CARRIAGE +RETURN/LINE FEED (code points 16#0D# 16#0A#) signifies a single end of line (see 2.2); every other +occurrence of a format_effector other than the character whose code point position is 16#09# +(CHARACTER TABULATION) also signifies a single end of line. + +Implementation Permissions + +The categories defined above, as well as case mapping and folding, may be based on an implementation- +defined version of ISO/IEC 10646 (2003 edition or later). + +NOTES +1 The characters in categories other_control, other_private_use, and other_surrogate are only allowed in comments. + +2.2 Lexical Elements, Separators, and Delimiters + +Static Semantics + +The text of a program consists of the texts of one or more compilations. The text of each compilation is a +sequence of separate lexical elements. Each lexical element is formed from a sequence of characters, and +is either a delimiter, an identifier, a reserved word, a numeric_literal, a character_literal, a string_literal, or +a comment. The meaning of a program depends only on the particular sequences of lexical elements that +form its compilations, excluding comments. + +The text of a compilation is divided into lines. In general, the representation for an end of line is +implementation defined. However, a sequence of one or more format_effectors other than the character +whose code point is 16#09# (CHARACTER TABULATION) signifies at least one end of line. + +In some cases an explicit separator is required to separate adjacent lexical elements. A separator is any of +a separator_space, a format_effector, or the end of a line, as follows: + +• A separator_space is a separator except within a comment, a string_literal, or a + +character_literal. + +• The character whose code point is 16#09# (CHARACTER TABULATION) is a separator + +except within a comment. + +• The end of a line is always a separator. + +One or more separators are allowed between any two adjacent lexical elements, before the first of each +compilation, or after the last. At least one separator is required between an identifier, a reserved word, or a +numeric_literal and an adjacent identifier, reserved word, or numeric_literal. + +16/3 + +17/3 + +18/2 + +1 + +2/3 + +3/2 + +4/2 + +5/3 + +6 + +7 + +One or more other_format characters are allowed anywhere that a separator is; any such characters have +no effect on the meaning of an Ada program. + +7.1/3 + +A delimiter is either one of the following characters: + +& ' ( ) * + , – . / : ; < = > | + +or one of the following compound delimiters each composed of two adjacent special characters + +=> .. ** := /= >= <= << >> <> + +8/2 + +9 + +10 + +11 + +11 13 December 2012 + +Character Set 2.1 + + Ada Reference Manual — 2012 Edition + +12 + +Each of the special characters listed for single character delimiters is a single delimiter except if this +character is used as a character of a compound delimiter, or as a character of a comment, string_literal, +character_literal, or numeric_literal. + +13 + +The following names are used when referring to compound delimiters: + + delimiter + => + .. + ** + := + /= + >= + <= + << + >> + <> + +name + +arrow + +double dot + +double star, exponentiate + +assignment (pronounced: “becomes”) + +inequality (pronounced: “not equal”) + +greater than or equal + +less than or equal + +left label bracket + +right label bracket + +box + +14 + +An implementation shall support lines of at least 200 characters in length, not counting any characters used +to signify the end of a line. An implementation shall support lexical elements of at least 200 characters in +length. The maximum supported line length and lexical element length are implementation defined. + +Implementation Requirements + +2.3 Identifiers + +1 + +Identifiers are used as names. + +2/2 + +3/2 + +3.1/3 + +identifier ::= + identifier_start {identifier_start | identifier_extend} + +Syntax + +identifier_start ::= + letter_uppercase + | letter_lowercase + | letter_titlecase + | letter_modifier + | letter_other + | number_letter + +identifier_extend ::= + mark_non_spacing + | mark_spacing_combining + | number_decimal + | punctuation_connector + +4/3 + +An identifier shall not contain two consecutive characters in category punctuation_connector, or end +with a character in that category. + +2.2 Lexical Elements, Separators, and Delimiters + +13 December 2012 12 + + + + Ada Reference Manual — 2012 Edition + +Static Semantics + +Two identifiers are considered the same if they consist of the same sequence of characters after applying +locale-independent simple case folding, as defined by documents referenced in the note in Clause 1 of +ISO/IEC 10646:2011. + +After applying simple case folding, an identifier shall not be identical to a reserved word. + +5/3 + +5.1/3 + +In a nonstandard mode, an implementation may support other upper/lower case equivalence rules for +identifiers, to accommodate local conventions. + +6 + +Implementation Permissions + +NOTES +2 Identifiers differing only in the use of corresponding upper and lower case letters are considered the same. + +Examples + +Examples of identifiers: + +Count X Get_Symbol Ethelyn Marion +Snobol_4 X1 Page_Count Store_Next_Item +Πλάτων -- Plato +Чайковский -- Tchaikovsky +θ φ -- Angles + +2.4 Numeric Literals + +There are two kinds of numeric_literals, real literals and integer literals. A real literal is a numeric_literal +that includes a point; an integer literal is a numeric_literal without a point. + +numeric_literal ::= decimal_literal | based_literal + +Syntax + +NOTES +3 The type of an integer literal is universal_integer. The type of a real literal is universal_real. + +2.4.1 Decimal Literals + +A decimal_literal is a numeric_literal in the conventional decimal notation (that is, the base is ten). + +Syntax +decimal_literal ::= numeral [.numeral] [exponent] + +numeral ::= digit {[underline] digit} + +exponent ::= E [+] numeral | E – numeral + +digit ::= 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 + +An exponent for an integer literal shall not have a minus sign. + +Static Semantics + +An underline character in a numeric_literal does not affect its meaning. The letter E of an exponent can be +written either in lower case or in upper case, with the same meaning. + +An exponent indicates the power of ten by which the value of the decimal_literal without the exponent is +to be multiplied to obtain the value of the decimal_literal with the exponent. + +13 13 December 2012 + +Identifiers 2.3 + +6.1/2 + +7 + +8/2 + +1 + +2 + +3 + +1 + +2 + +3 + +4 + +4.1/2 + +5 + +6 + +7 + + Ada Reference Manual — 2012 Edition + +Examples of decimal literals: + +12 0 1E6 123_456 -- integer literals + +12.0 0.0 0.456 3.14159_26 -- real literals + +Examples + +2.4.2 Based Literals + +A based_literal is a numeric_literal expressed in a form that specifies the base explicitly. + +based_literal ::= + base # based_numeral [.based_numeral] # [exponent] + +Syntax + +base ::= numeral + +based_numeral ::= + extended_digit {[underline] extended_digit} + +extended_digit ::= digit | A | B | C | D | E | F + +Legality Rules + +The base (the numeric value of the decimal numeral preceding the first #) shall be at least two and at most +sixteen. The extended_digits A through F represent the digits ten through fifteen, respectively. The value +of each extended_digit of a based_literal shall be less than the base. + +Static Semantics + +The conventional meaning of based notation is assumed. An exponent indicates the power of the base by +which the value of the based_literal without the exponent is to be multiplied to obtain the value of the +based_literal with the exponent. The base and the exponent, if any, are in decimal notation. + +The extended_digits A through F can be written either in lower case or in upper case, with the same +meaning. + +Examples of based literals: + +Examples + +2#1111_1111# 16#FF# 016#0ff# -- integer literals of value 255 +16#E#E1 2#1110_0000# -- integer literals of value 224 +16#F.FF#E+2 2#1.1111_1111_1110#E11 -- real literals of value 4095.0 + +2.5 Character Literals + +A character_literal is formed by enclosing a graphic character between two apostrophe characters. + +character_literal ::= 'graphic_character' + +NOTES +4 A character_literal is an enumeration literal of a character type. See 3.5.2. + +Syntax + +8 + +9 + +1 + +2 + +3 + +4 + +5 + +6 + +7 + +8 + +9 + +10 + +1 + +2 + +3 + +2.4.1 Decimal Literals + +13 December 2012 14 + + + Ada Reference Manual — 2012 Edition + +Examples of character literals: + +'A' '*' ''' ' ' +'L' 'Л' 'Λ' -- Various els. +'∞' 'א' -- Big numbers - infinity and aleph. + +Examples + +2.6 String Literals + +A string_literal is formed by a sequence of graphic characters (possibly none) enclosed between two +quotation marks used as string brackets. They are used to represent operator_symbols (see 6.1), values of +a string type (see 4.2), and array subaggregates (see 4.3.3). + +string_literal ::= "{string_element}" + +string_element ::= "" | non_quotation_mark_graphic_character + +Syntax + +A string_element is either a pair of quotation marks (""), or a single graphic_character other than a +quotation mark. + +Static Semantics + +The sequence of characters of a string_literal is formed from the sequence of string_elements between the +bracketing quotation marks, in the given order, with a string_element that is "" becoming a single +quotation mark in the sequence of characters, and any other string_element being reproduced in the +sequence. + +A null string literal is a string_literal with no string_elements between the quotation marks. + +NOTES +5 An end of line cannot appear in a string_literal. + +6 No transformation is performed on the sequence of characters of a string_literal. + +Examples of string literals: + +"Message of the day:" + +Examples + +"" -- a null string literal +" " "A" """" -- three string literals of length 1 + +"Characters such as $, %, and } are allowed in string literals" +"Archimedes said ""Εύρηκα""" +"Volume of cylinder (πr²h) = " + +2.7 Comments + +A comment starts with two adjacent hyphens and extends up to the end of the line. + +comment ::= --{non_end_of_line_character} + +A comment may appear on any line of a program. + +Syntax + +4 + +5/2 + +1 + +2 + +3 + +4 + +5 + +6 + +7 + +7.1/2 + +8 + +9/2 + +1 + +2 + +3 + +15 13 December 2012 + +Character Literals 2.5 + + + + 4 + +5 + +6 + +1 + +2 + +3/3 + +4/3 + +5 + +6 + +7/3 + +7.1/3 + +7.2/3 + +8 + +9 + +10/3 + +Ada Reference Manual — 2012 Edition + +The presence or absence of comments has no influence on whether a program is legal or illegal. +Furthermore, comments do not influence the meaning of a program; their sole purpose is the +enlightenment of the human reader. + +Static Semantics + +Examples of comments: + +-- the last sentence above echoes the Algol 68 report + +Examples + +end; -- processing of Line is complete + +-- a long comment may be split onto +-- two or more consecutive lines + +---------------- the first two hyphens start the comment + +2.8 Pragmas + +A pragma is a compiler directive. There are language-defined pragmas that give instructions for +optimization, listing control, etc. An implementation may support additional (implementation-defined) +pragmas. + +pragma ::= + pragma identifier [(pragma_argument_association {, pragma_argument_association})]; + +Syntax + +pragma_argument_association ::= + [pragma_argument_identifier =>] name + | [pragma_argument_identifier =>] expression + | pragma_argument_aspect_mark => name + | pragma_argument_aspect_mark => expression + +In a pragma, any pragma_argument_associations without a pragma_argument_identifier or +pragma_argument_aspect_mark shall precede any associations with a pragma_argument_identifier +or pragma_argument_aspect_mark. + +Pragmas are only allowed at the following places in a program: + +• After a semicolon delimiter, but not within a formal_part or discriminant_part. +• At any place where the syntax rules allow a construct defined by a syntactic category +whose name ends with “declaration”, “item”, “statement”, “clause”, or “alternative”, or +one of the syntactic categories variant or exception_handler; but not in place of such a +construct if the construct is required, or is part of a list that is required to have at least one +such construct. + +• In place of a statement in a sequence_of_statements. +• At any place where a compilation_unit is allowed. + +Additional syntax rules and placement restrictions exist for specific pragmas. + +The name of a pragma is the identifier following the reserved word pragma. The name or expression of +a pragma_argument_association is a pragma argument. + +An identifier specific to a pragma is an identifier or reserved word that is used in a pragma argument with +special meaning for that pragma. + +2.7 Comments + +13 December 2012 16 + + + + + Ada Reference Manual — 2012 Edition + +If an implementation does not recognize the name of a pragma, then it has no effect on the semantics of +the program. Inside such a pragma, the only rules that apply are the Syntax Rules. + +Static Semantics + +Any pragma that appears at the place of an executable construct is executed. Unless otherwise specified +for a particular pragma, this execution consists of the evaluation of each evaluable pragma argument in an +arbitrary order. + +Dynamic Semantics + +The implementation shall give a warning message for an unrecognized pragma name. + +Implementation Requirements + +Implementation Permissions + +An implementation may provide implementation-defined pragmas; the name of an implementation-defined +pragma shall differ from those of the language-defined pragmas. + +An implementation may ignore an unrecognized pragma even if it violates some of the Syntax Rules, if +detecting the syntax error is too complex. + +Implementation Advice + +Normally, implementation-defined pragmas should have no semantic effect for error-free programs; that +is, if the implementation-defined pragmas in a working program are replaced with unrecognized pragmas, +the program should still be legal, and should still have the same semantics. + +Normally, an implementation should not define pragmas that can make an illegal program legal, except as +follows: + +• A pragma used to complete a declaration; +• A pragma used to configure the environment by adding, removing, or replacing library_items. + +The forms of List, Page, and Optimize pragmas are as follows: + pragma List(identifier); + +Syntax + + pragma Page; + + pragma Optimize(identifier); + +Other pragmas are defined throughout this International Standard, and are summarized in Annex L. + +Static Semantics + +A pragma List takes one of the identifiers On or Off as the single argument. This pragma is allowed +anywhere a pragma is allowed. It specifies that listing of the compilation is to be continued or suspended +until a List pragma with the opposite argument is given within the same compilation. The pragma itself is +always listed if the compiler is producing a listing. + +A pragma Page is allowed anywhere a pragma is allowed. It specifies that the program text which follows +the pragma should start on a new page (if the compiler is currently producing a listing). + +A pragma Optimize takes one of the identifiers Time, Space, or Off as the single argument. This pragma +is allowed anywhere a pragma is allowed, and it applies until the end of the immediately enclosing +declarative region, or for a pragma at the place of a compilation_unit, to the end of the compilation. It + +11 + +12 + +13 + +14 + +15 + +16/3 + +17 + +18/3 + +19 + +20 + +21 + +22 + +23 + +24 + +25 + +26 + +27 + +17 13 December 2012 + +Pragmas 2.8 + + Ada Reference Manual — 2012 Edition + +gives advice to the implementation as to whether time or space is the primary optimization criterion, or +that optional optimizations should be turned off. It is implementation defined how this advice is followed. + +28 + +Examples of pragmas: + +Examples + +29/3 + +1/1 + +2/3 + +pragma List(Off); -- turn off listing generation +pragma Optimize(Off); -- turn off optional optimizations +pragma Pure(Rational_Numbers); -- set categorization for package +pragma Assert(Exists(File_Name), + Message => "Nonexistent file"); -- assert file exists + +2.9 Reserved Words + +This paragraph was deleted. + +Syntax + +The following are the reserved words. Within a program, some or all of the letters of a reserved word +may be in upper case. + +abort +abs +abstract +accept +access +aliased +all +and +array +at + +begin +body + +case +constant + +declare +delay +delta +digits +do + +else +elsif +end +entry +exception +exit + +for +function + +generic +goto + +if +in +interface +is + +limited +loop + +mod + +new +not +null + +of +or +others +out +overriding + +package +pragma +private +procedure +protected + +raise +range +record +rem +renames +requeue + +return +reverse + +select +separate +some +subtype +synchronized + +tagged +task +terminate +then +type + +until +use + +when +while +with + +xor + +3 + +NOTES +7 The reserved words appear in lower case boldface in this International Standard, except when used in the designator of +an attribute (see 4.1.4). Lower case boldface is also used for a reserved word in a string_literal used as an +operator_symbol. This is merely a convention — programs may be written in whatever typeface is desired and available. + +2.8 Pragmas + +13 December 2012 18 + + Ada Reference Manual — 2012 Edition + +3 Declarations and Types + +This clause describes the types in the language and the rules for declaring constants, variables, and named +numbers. + +1/3 + +3.1 Declarations + +The language defines several kinds of named entities that are declared by declarations. The entity's name +is defined by the declaration, usually by a defining_identifier, but sometimes by a defining_character_- +literal or defining_operator_symbol. + +There are several forms of declaration. A basic_declaration is a form of declaration defined as follows. + +basic_declaration ::= + type_declaration + | object_declaration + | subprogram_declaration + | null_procedure_declaration + | package_declaration + | exception_declaration + | generic_instantiation + +defining_identifier ::= identifier + +Syntax + +| subtype_declaration +| number_declaration +| abstract_subprogram_declaration +| expression_function_declaration +| renaming_declaration +| generic_declaration + +Static Semantics + +A declaration is a language construct that associates a name with (a view of) an entity. A declaration may +appear explicitly in the program text (an explicit declaration), or may be supposed to occur at a given place +in the text as a consequence of the semantics of another construct (an implicit declaration). + +Each of the following is defined to be a declaration: any basic_declaration; an enumeration_literal_- +specification; a discriminant_specification; a component_declaration; a loop_parameter_specification; +an iterator_specification; a parameter_specification; a subprogram_body; an extended_return_object_- +declaration; an entry_declaration; an entry_index_specification; a choice_parameter_specification; a +generic_formal_parameter_declaration. + +All declarations contain a definition for a view of an entity. A view consists of an identification of the +entity (the entity of the view), plus view-specific characteristics that affect the use of the entity through +that view (such as mode of access to an object, formal parameter names and defaults for a subprogram, or +visibility to components of a type). In most cases, a declaration also contains the definition for the entity +itself (a renaming_declaration is an example of a declaration that does not define a new entity, but instead +defines a view of an existing entity (see 8.5)). + +1 + +2 + +3/3 + +4 + +5 + +6/3 + +7 + +When it is clear from context, the term object is used in place of view of an object. Similarly, the terms +type and subtype are used in place of view of a type and view of a subtype, respectively. + +7.1/3 + +For each declaration, the language rules define a certain region of text called the scope of the declaration +(see 8.2). Most declarations associate an identifier with a declared entity. Within its scope, and only there, +there are places where it is possible to use the identifier to refer to the declaration, the view it defines, and +the associated entity; these places are defined by the visibility rules (see 8.3). At such places the identifier +is said to be a name of the entity (the direct_name or selector_name); the name is said to denote the + +8 + +19 13 December 2012 + +Declarations and Types 3 + + Ada Reference Manual — 2012 Edition + +declaration, the view, and the associated entity (see 8.6). The declaration is said to declare the name, the +view, and in most cases, the entity itself. + +As an alternative to an identifier, an enumeration literal can be declared with a character_literal as its +name (see 3.5.1), and a function can be declared with an operator_symbol as its name (see 6.1). + +The syntax rules use the terms defining_identifier, defining_character_literal, and defining_operator_- +symbol for the defining occurrence of a name; these are collectively called defining names. The terms +direct_name and selector_name are used for usage occurrences of identifiers, character_literals, and +operator_symbols. These are collectively called usage names. + +Dynamic Semantics + +The process by which a construct achieves its run-time effect is called execution. This process is also +called elaboration for declarations and evaluation for expressions. One of the terms execution, +elaboration, or evaluation is defined by this International Standard for each construct that has a run-time +effect. + +NOTES +1 At compile time, the declaration of an entity declares the entity. At run time, the elaboration of the declaration creates +the entity. + +3.2 Types and Subtypes + +Static Semantics + +A type is characterized by a set of values, and a set of primitive operations which implement the +fundamental aspects of its semantics. An object of a given type is a run-time entity that contains (has) a +value of the type. + +Types are grouped into categories of types. There exist several language-defined categories of types (see +NOTES below), reflecting the similarity of their values and primitive operations. Most categories of types +form classes of types. Elementary types are those whose values are logically indivisible; composite types +are those whose values are composed of component values. + +The elementary types are the scalar types (discrete and real) and the access types (whose values provide +access to objects or subprograms). Discrete types are either integer types or are defined by enumeration of +their values (enumeration types). Real types are either floating point types or fixed point types. + +The composite types are the record types, record extensions, array types, interface types, task types, and +protected types. + +There can be multiple views of a type with varying sets of operations. An incomplete type represents an +incomplete view (see 3.10.1) of a type with a very restricted usage, providing support for recursive data +structures. A private type or private extension represents a partial view (see 7.3) of a type, providing +support for data abstraction. The full view (see 3.2.1) of a type represents its complete definition. An +incomplete or partial view is considered a composite type, even if the full view is not. + +Certain composite types (and views thereof) have special components called discriminants whose values +affect the presence, constraints, or initialization of other components. Discriminants can be thought of as +parameters of the type. + +The term subcomponent is used in this International Standard in place of the term component to indicate +either a component, or a component of another subcomponent. Where other subcomponents are excluded, + +9 + +10 + +11 + +12 + +1 + +2/2 + +3 + +4/2 + +4.1/2 + +5/2 + +6/2 + +3.1 Declarations + +13 December 2012 20 + + 7/2 + +8/2 + +9 + +10/2 + +11/2 + +12/2 + +Ada Reference Manual — 2012 Edition + +the term component is used instead. Similarly, a part of an object or value is used to mean the whole +object or value, or any set of its subcomponents. The terms component, subcomponent, and part are also +applied to a type meaning the component, subcomponent, or part of objects and values of the type. + +The set of possible values for an object of a given type can be subjected to a condition that is called a +constraint (the case of a null constraint that specifies no restriction is also included); the rules for which +values satisfy a given kind of constraint are given in 3.5 for range_constraints, 3.6.1 for +index_constraints, and 3.7.1 for discriminant_constraints. The set of possible values for an object of an +access type can also be subjected to a condition that excludes the null value (see 3.10). + +A subtype of a given type is a combination of the type, a constraint on values of the type, and certain +attributes specific to the subtype. The given type is called the type of the subtype. Similarly, the associated +constraint is called the constraint of the subtype. The set of values of a subtype consists of the values of its +type that satisfy its constraint and any exclusion of the null value. Such values belong to the subtype. + +A subtype is called an unconstrained subtype if its type has unknown discriminants, or if its type allows +range, index, or discriminant constraints, but the subtype does not impose such a constraint; otherwise, the +subtype is called a constrained subtype (since it has no unconstrained characteristics). + +NOTES +2 Any set of types can be called a “category” of types, and any set of types that is closed under derivation (see 3.4) can be +called a “class” of types. However, only certain categories and classes are used in the description of the rules of the +language — generally those that have their own particular set of primitive operations (see 3.2.3), or that correspond to a +set of types that are matched by a given kind of generic formal type (see 12.5). The following are examples of +“interesting” language-defined classes: elementary, scalar, discrete, enumeration, character, boolean, integer, signed +integer, modular, real, floating point, fixed point, ordinary fixed point, decimal fixed point, numeric, access, access-to- +object, access-to-subprogram, composite, array, string, (untagged) record, tagged, task, protected, nonlimited. Special +syntax is provided to define types in each of these classes. In addition to these classes, the following are examples of +“interesting” language-defined categories: abstract, incomplete, interface, limited, private, record. + +These language-defined categories are organized like this: + +all types + +elementary +scalar + +discrete + +enumeration + +character +boolean +other enumeration + +integer + +signed integer +modular integer + +real + +floating point +fixed point + +ordinary fixed point +decimal fixed point + +access + +access-to-object +access-to-subprogram + +composite + +untagged + +array + +string +other array + +record +task +protected + +21 13 December 2012 + +Types and Subtypes 3.2 + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + Ada Reference Manual — 2012 Edition + +tagged (including interfaces) + +nonlimited tagged record +limited tagged + +limited tagged record +synchronized tagged + +tagged task +tagged protected + +13/2 + +There are other categories, such as “numeric” and “discriminated”, which represent other categorization dimensions, but +do not fit into the above strictly hierarchical picture. + +1 + +2 + +3/3 + +4/2 + +5 + +6 + +7/2 + +8/2 + +3.2.1 Type Declarations + +A type_declaration declares a type and its first subtype. + +type_declaration ::= full_type_declaration + | incomplete_type_declaration + | private_type_declaration + | private_extension_declaration + +Syntax + +full_type_declaration ::= + type defining_identifier [known_discriminant_part] is type_definition + [aspect_specification]; + | task_type_declaration + | protected_type_declaration + +type_definition ::= + enumeration_type_definition + | real_type_definition + | record_type_definition + | derived_type_definition + +| integer_type_definition +| array_type_definition +| access_type_definition +| interface_type_definition + +Legality Rules + +A given type shall not have a subcomponent whose type is the given type itself. + +Static Semantics + +The defining_identifier of a type_declaration denotes the first subtype of the type. The known_- +discriminant_part, if any, defines the discriminants of the type (see 3.7, “Discriminants”). The remainder +of the type_declaration defines the remaining characteristics of (the view of) the type. + +A type defined by a type_declaration is a named type; such a type has one or more nameable subtypes. +Certain other forms of declaration also include type definitions as part of the declaration for an object. The +type defined by such a declaration is anonymous — it has no nameable subtypes. For explanatory +purposes, this International Standard sometimes refers to an anonymous type by a pseudo-name, written in +italics, and uses such pseudo-names at places where the syntax normally requires an identifier. For a +named type whose first subtype is T, this International Standard sometimes refers to the type of T as +simply “the type T”. + +A named type that is declared by a full_type_declaration, or an anonymous type that is defined by an +access_definition or as part of declaring an object of the type, is called a full type. The declaration of a +full type also declares the full view of the type. The type_definition, task_definition, protected_definition, +or access_definition that defines a full type is called a full type definition. Types declared by other forms +of type_declaration are not separate types; they are partial or incomplete views of some full type. + +3.2 Types and Subtypes + +13 December 2012 22 + + + + + + + + + + + + + + + + + + + + + + + + + + + + Ada Reference Manual — 2012 Edition + +The definition of a type implicitly declares certain predefined operators that operate on the type, +according to what classes the type belongs, as specified in 4.5, “Operators and Expression Evaluation”. + +The predefined types (for example the types Boolean, Wide_Character, Integer, root_integer, and +universal_integer) are the types that are defined in a predefined library package called Standard; this +package also includes the (implicit) declarations of their predefined operators. The package Standard is +described in A.1. + +The elaboration of a full_type_declaration consists of the elaboration of the full type definition. Each +elaboration of a full type definition creates a distinct type and its first subtype. + +Dynamic Semantics + +Examples of type definitions: + +(White, Red, Yellow, Green, Blue, Brown, Black) +range 1 .. 72 +array(1 .. 10) of Integer + +Examples + +Examples of type declarations: + +type Color is (White, Red, Yellow, Green, Blue, Brown, Black); +type Column is range 1 .. 72; +type Table is array(1 .. 10) of Integer; + +NOTES +3 Each of the above examples declares a named type. The identifier given denotes the first subtype of the type. Other +named subtypes of the type can be declared with subtype_declarations (see 3.2.2). Although names do not directly denote +types, a phrase like “the type Column” is sometimes used in this International Standard to refer to the type of Column, +where Column denotes the first subtype of the type. For an example of the definition of an anonymous type, see the +declaration of the array Color_Table in 3.3.1; its type is anonymous — it has no nameable subtypes. + +9 + +10 + +11 + +12 + +13 + +14 + +15 + +16 + +3.2.2 Subtype Declarations + +A subtype_declaration declares a subtype of some previously declared type, as defined by a +subtype_indication. + +1 + +subtype_declaration ::= + subtype defining_identifier is subtype_indication + [aspect_specification]; + +Syntax + +subtype_indication ::= [null_exclusion] subtype_mark [constraint] + +subtype_mark ::= subtype_name + +constraint ::= scalar_constraint | composite_constraint + +scalar_constraint ::= + range_constraint | digits_constraint | delta_constraint + +composite_constraint ::= + index_constraint | discriminant_constraint + +Name Resolution Rules + +A subtype_mark shall resolve to denote a subtype. The type determined by a subtype_mark is the type of +the subtype denoted by the subtype_mark. + +23 13 December 2012 + +Type Declarations 3.2.1 + +2/3 + +3/2 + +4 + +5 + +6 + +7 + +8 + + Ada Reference Manual — 2012 Edition + +Dynamic Semantics + +9 + +10 + +11 + +12 + +13 + +The elaboration of a subtype_declaration consists of the elaboration of the subtype_indication. The +elaboration of a subtype_indication creates a new subtype. If the subtype_indication does not include a +constraint, the new subtype has the same (possibly null) constraint as that denoted by the subtype_mark. +The elaboration of a subtype_indication that includes a constraint proceeds as follows: + +• The constraint is first elaborated. +• A check is then made that the constraint is compatible with the subtype denoted by the + +subtype_mark. + +The condition imposed by a constraint is the condition obtained after elaboration of the constraint. The +rules defining compatibility are given for each form of constraint in the appropriate subclause. These rules +are such that if a constraint is compatible with a subtype, then the condition imposed by the constraint +cannot contradict any condition already imposed by the subtype on its values. The exception +Constraint_Error is raised if any check of compatibility fails. + +NOTES +4 A scalar_constraint may be applied to a subtype of an appropriate scalar type (see 3.5, 3.5.9, and J.3), even if the +subtype is already constrained. On the other hand, a composite_constraint may be applied to a composite subtype (or an +access-to-composite subtype) only if the composite subtype is unconstrained (see 3.6.1 and 3.7.1). + +14 + +Examples of subtype declarations: + +Examples + +15/2 + +1/2 + +2 + +3 + +4 + +5 + +6 + +subtype Rainbow is Color range Red .. Blue; -- see 3.2.1 +subtype Red_Blue is Rainbow; +subtype Int is Integer; +subtype Small_Int is Integer range -10 .. 10; +subtype Up_To_K is Column range 1 .. K; -- see 3.2.1 +subtype Square is Matrix(1 .. 10, 1 .. 10); -- see 3.6 +subtype Male is Person(Sex => M); -- see 3.10.1 +subtype Binop_Ref is not null Binop_Ptr; -- see 3.10 + +3.2.3 Classification of Operations + +Static Semantics + +An operation operates on a type T if it yields a value of type T, if it has an operand whose expected type +(see 8.6) is T, or if it has an access parameter or access result type (see 6.1) designating T. A predefined +operator, or other language-defined operation such as assignment or a membership test, that operates on a +type, is called a predefined operation of the type. The primitive operations of a type are the predefined +operations of the type, plus any user-defined primitive subprograms. + +The primitive subprograms of a specific type are defined as follows: + +• The predefined operators of the type (see 4.5); +• For a derived type, the inherited (see 3.4) user-defined subprograms; +• For an enumeration type, the enumeration literals (which are considered parameterless functions + +— see 3.5.1); + +• For a specific type declared immediately within a package_specification, any subprograms (in +addition to the enumeration literals) that are explicitly declared immediately within the same +package_specification and that operate on the type; + +6.1/3 + +• For a specific type with an explicitly declared primitive "=" operator whose result type is + +Boolean, the corresponding "/=" operator (see 6.6); + +3.2.2 Subtype Declarations + +13 December 2012 24 + + Ada Reference Manual — 2012 Edition + +• For a nonformal type, any subprograms not covered above that are explicitly declared +immediately within the same declarative region as the type and that override (see 8.3) other +implicitly declared primitive subprograms of the type. + +A primitive subprogram whose designator is an operator_symbol is called a primitive operator. + +3.2.4 Subtype Predicates + +The language-defined predicate aspects Static_Predicate and Dynamic_Predicate may be used to define +properties of subtypes. A predicate specification is an aspect_specification for one of the two predicate +aspects. General rules for aspects and aspect_specifications are found in Clause 13 (13.1 and 13.1.1 +respectively). + +The expected type for a predicate aspect expression is any boolean type. + +Name Resolution Rules + +Static Semantics + +A predicate specification may be given on a type_declaration or a subtype_declaration, and applies to the +declared subtype. In addition, predicate specifications apply to certain other subtypes: + +• For a (first) subtype defined by a derived type declaration, the predicates of the parent subtype + +and the progenitor subtypes apply. + +• For a subtype created by a subtype_indication, the predicate of the subtype denoted by the + +subtype_mark applies. + +The predicate of a subtype consists of all predicate specifications that apply, and-ed together; if no +predicate specifications apply, the predicate is True (in particular, the predicate of a base subtype is True). + +Predicate checks are defined to be enabled or disabled for a given subtype as follows: + +• If a subtype is declared by a type_declaration or subtype_declaration that includes a predicate + +specification, then: + +• + +• + +if performing checks is required by the Static_Predicate assertion policy (see 11.4.2) and +the declaration includes a Static_Predicate specification, then predicate checks are enabled +for the subtype; + +if performing checks is required by the Dynamic_Predicate assertion policy (see 11.4.2) +and the declaration includes a Dynamic_Predicate specification, then predicate checks are +enabled for the subtype; + +• otherwise, predicate checks are disabled for the subtype, regardless of whether predicate + +checking is enabled for any other subtypes mentioned in the declaration; + +• If a subtype is defined by a derived type declaration that does not include a predicate +specification, then predicate checks are enabled for the subtype if and only if predicate checks +are enabled for at least one of the parent subtype and the progenitor subtypes; + +• If a subtype is created by a subtype_indication other than in one of the previous cases, then +predicate checks are enabled for the subtype if and only if predicate checks are enabled for the +subtype denoted by the subtype_mark; + +• Otherwise, predicate checks are disabled for the given subtype. + +7/2 + +8 + +1/3 + +2/3 + +3/3 + +4/3 + +5/3 + +6/3 + +7/3 + +8/3 + +9/3 + +10/3 + +11/3 + +12/3 + +13/3 + +14/3 + +The expression of a Static_Predicate specification shall be predicate-static; that is, one of the following: + +15/3 + +Legality Rules + +25 13 December 2012 + +Classification of Operations 3.2.3 + + Ada Reference Manual — 2012 Edition + +16/3 + +17/3 + +• a static expression; +• a membership + +test whose simple_expression + +is + +the current + +instance, and whose + +membership_choice_list meets the requirements for a static membership test (see 4.9); + +18/3 + +• a case_expression whose selecting_expression + +is + +the current + +instance, and whose + +dependent_expressions are static expressions; + +19/3 + +• a call to a predefined equality or ordering operator, where one operand is the current instance, + +and the other is a static expression; + +20/3 + +21/3 + +22/3 + +23/3 + +24/3 + +25/3 + +26/3 + +27/3 + +28/3 + +29/3 + +30/3 + +31/3 + +• a call to a predefined boolean logical operator, where each operand is predicate-static; +• a short-circuit control form where both operands are predicate-static; or +• a parenthesized predicate-static expression. + +A predicate shall not be specified for an incomplete subtype. + +If a predicate applies to a subtype, then that predicate shall not mention any other subtype to which the +same predicate applies. + +An index subtype, discrete_range of an index_constraint or slice, or a discrete_subtype_definition of a +constrained_array_definition, entry_declaration, or entry_index_specification shall not denote a subtype +to which predicate specifications apply. + +The prefix of an attribute_reference whose attribute_designator is First, Last, or Range shall not denote a +scalar subtype to which predicate specifications apply. + +The discrete_subtype_definition of a loop_parameter_specification shall not denote a nonstatic subtype +to which predicate specifications apply or any subtype to which Dynamic_Predicate specifications apply. + +The discrete_choice of a named_array_aggregate shall not denote a nonstatic subtype to which +predicate specifications apply. + +In addition to the places where Legality Rules normally apply (see 12.3), these rules apply also in the +private part of an instance of a generic unit. + +If predicate checks are enabled for a given subtype, then: + +Dynamic Semantics + +On every subtype conversion, the predicate of the target subtype is evaluated, and a check is +performed that the predicate is True. This includes all parameter passing, except for certain +parameters passed by reference, which are covered by the following rule: After normal +completion and leaving of a subprogram, for each in out or out parameter that is passed by +reference, the predicate of the subtype of the actual is evaluated, and a check is performed that +the predicate is True. For an object created by an object_declaration with no explicit +initialization expression, or by an uninitialized allocator, if any subcomponents have +default_expressions, the predicate of the nominal subtype of the created object is evaluated, and +a check is performed that the predicate is True. Assertions.Assertion_Error is raised if any of +these checks fail. + +32/3 + +A value satisfies a predicate if the predicate is True for that value. + +33/3 + +If any of the above Legality Rules is violated in an instance of a generic unit, Program_Error is raised at +the point of the violation. + +3.2.4 Subtype Predicates + +13 December 2012 26 + + Ada Reference Manual — 2012 Edition + +NOTES +5 A predicate specification does not cause a subtype to be considered constrained. + +6 A Static_Predicate, like a constraint, always remains True for all objects of the subtype, except in the case of +uninitialized variables and other invalid values. A Dynamic_Predicate, on the other hand, is checked as specified above, +but can become False at other times. For example, the predicate of a record subtype is not checked when a subcomponent +is modified. + +3.3 Objects and Named Numbers + +Objects are created at run time and contain a value of a given type. An object can be created and initialized +as part of elaborating a declaration, evaluating an allocator, aggregate, or function_call, or passing a +parameter by copy. Prior to reclaiming the storage for an object, it is finalized if necessary (see 7.6.1). + +All of the following are objects: + +Static Semantics + +the entity declared by an object_declaration; + +• +• a formal parameter of a subprogram, entry, or generic subprogram; +• a generic formal object; +• a loop parameter; +• a choice parameter of an exception_handler; +• an entry index of an entry_body; +• +• +• +• a qualified_expression whose operand denotes an object; +• a component, slice, or view conversion of another object. + +the result of dereferencing an access-to-object value (see 4.1); + +the result of evaluating an aggregate; + +the return object of a function; + +An object is either a constant object or a variable object. Similarly, a view of an object is either a constant +or a variable. All views of a constant elementary object are constant. All views of a constant composite +object are constant, except for parts that are of controlled or immutably limited types; variable views of +those parts and their subcomponents may exist. In this sense, objects of controlled and immutably limited +types are inherently mutable. A constant view of an object cannot be used to modify its value. The terms +constant and variable by themselves refer to constant and variable views of objects. + +The value of an object is read when the value of any part of the object is evaluated, or when the value of +an enclosing object is evaluated. The value of a variable is updated when an assignment is performed to +any part of the variable, or when an assignment is performed to an enclosing object. + +Whether a view of an object is constant or variable is determined by the definition of the view. The +following (and no others) represent constants: + +• an object declared by an object_declaration with the reserved word constant; +• a formal parameter or generic formal object of mode in; +• a discriminant; +• a loop parameter unless specified to be a variable for a generalized loop (see 5.5.2); +• a choice parameter or entry index; + +27 13 December 2012 + +Subtype Predicates 3.2.4 + +34/3 + +35/3 + +1 + +2 + +3 + +4 + +5 + +6 + +7 + +8 + +9 + +10/3 + +11 + +11.1/3 + +12 + +13/3 + +14 + +15 + +16 + +17 + +18 + +18.1/3 + +19/3 + + Ada Reference Manual — 2012 Edition + +20 + +20.1/3 + +21/3 + +21.1/3 + +21.2/3 + +22 + +23/3 + +the dereference of an access-to-constant value; + +the return object declared by an extended_return_statement with the reserved word constant; + +• +• +• +• +• within the body of a protected function (or a function declared immediately within a + +the object denoted by a function_call or an aggregate; + +the result of evaluating a qualified_expression; + +protected_body), the current instance of the enclosing protected unit; + +• a selected_component, indexed_component, slice, or view conversion of a constant. + +At the place where a view of an object is defined, a nominal subtype is associated with the view. The +object's actual subtype (that is, its subtype) can be more restrictive than the nominal subtype of the view; it +always is if the nominal subtype is an indefinite subtype. A subtype is an indefinite subtype if it is an +unconstrained array subtype, or if it has unknown discriminants or unconstrained discriminants without +defaults (see 3.7); otherwise, the subtype is a definite subtype (all elementary subtypes are definite +subtypes). A class-wide subtype is defined to have unknown discriminants, and is therefore an indefinite +subtype. An indefinite subtype does not by itself provide enough information to create an object; an +additional constraint or explicit initialization expression is necessary (see 3.3.1). A component cannot +have an indefinite nominal subtype. + +23.1/3 + +A view of a composite object is known to be constrained if: + +23.2/3 + +23.3/3 + +23.4/3 + +23.5/3 + +23.6/3 + +23.7/3 + +23.8/3 + +23.9/3 + +• +• +• +• +• +• +• +• + +its nominal subtype is constrained, and is not an untagged partial view; or + +its nominal subtype is indefinite; or + +its type is immutably limited (see 7.5); or + +it is part of a stand-alone constant (including a generic formal object of mode in); or + +it is part of a formal parameter of mode in; or + +it is part of the object denoted by a function_call or aggregate; or + +it is part of a constant return object of an extended_return_statement; or + +it is a dereference of a pool-specific access type, and there is no ancestor of its type that has a +constrained partial view. + +23.10/3 + +For the purposes of determining within a generic body whether an object is known to be constrained: + +23.11/3 + +23.12/3 + +• + +• + +if a subtype is a descendant of an untagged generic formal private or derived type, and the +subtype is not an unconstrained array subtype, it is not considered indefinite and is considered to +have a constrained partial view; + +if a subtype is a descendant of a formal access type, it is not considered pool-specific. + +24 + +25 + +25.1/3 + +26/3 + +A named number provides a name for a numeric value known at compile time. It is declared by a +number_declaration. + +NOTES +7 A constant cannot be the target of an assignment operation, nor be passed as an in out or out parameter, between its +initialization and finalization, if any. + +8 The value of a constant object cannot be changed after its initialization, except in some cases where the object has a +controlled or immutably limited part (see 7.5, 7.6, and 13.9.1). + +9 The nominal and actual subtypes of an elementary object are always the same. For a discriminated or array object, if the +nominal subtype is constrained, then so is the actual subtype. + +3.3 Objects and Named Numbers + +13 December 2012 28 + + Ada Reference Manual — 2012 Edition + +3.3.1 Object Declarations + +An object_declaration declares a stand-alone object with a given nominal subtype and, optionally, an +explicit initial value given by an initialization expression. For an array, access, task, or protected object, +the object_declaration may include the definition of the (anonymous) type of the object. + +Syntax + +object_declaration ::= + defining_identifier_list : [aliased] [constant] subtype_indication [:= expression] + [aspect_specification]; + | defining_identifier_list : [aliased] [constant] access_definition [:= expression] + [aspect_specification]; + | defining_identifier_list : [aliased] [constant] array_type_definition [:= expression] + [aspect_specification]; + | single_task_declaration + | single_protected_declaration + +defining_identifier_list ::= + defining_identifier {, defining_identifier} + +Name Resolution Rules + +For an object_declaration with an expression following the compound delimiter :=, the type expected for +the expression is that of the object. This expression is called the initialization expression. + +An object_declaration without the reserved word constant declares a variable object. If it has a +subtype_indication or an array_type_definition that defines an indefinite subtype, then there shall be an +initialization expression. + +Legality Rules + +Static Semantics + +An object_declaration with the reserved word constant declares a constant object. If it has an +initialization expression, then it is called a full constant declaration. Otherwise, it is called a deferred +constant declaration. The rules for deferred constant declarations are given in subclause 7.4. The rules for +full constant declarations are given in this subclause. + +Any declaration that includes a defining_identifier_list with more than one defining_identifier is equivalent +to a series of declarations each containing one defining_identifier from the list, with the rest of the text of +the declaration copied for each declaration in the series, in the same order as the list. The remainder of this +International Standard relies on this equivalence; explanations are given for declarations with a single +defining_identifier. + +The subtype_indication, access_definition, or full type definition of an object_declaration defines the +nominal subtype of the object. The object_declaration declares an object of the type of the nominal +subtype. + +A component of an object is said to require late initialization if it has an access discriminant value +constrained by a per-object expression, or if it has an initialization expression that includes a name +denoting the current instance of the type or denoting an access discriminant. + +1/3 + +2/3 + +3 + +4 + +5/2 + +6/3 + +7 + +8/2 + +8.1/2 + +29 13 December 2012 + +Object Declarations 3.3.1 + + Ada Reference Manual — 2012 Edition + +Dynamic Semantics + +9/2 + +10 + +11 + +11.1/3 + +If a composite object declared by an object_declaration has an unconstrained nominal subtype, then if this +subtype is indefinite or the object is constant the actual subtype of this object is constrained. The +constraint is determined by the bounds or discriminants (if any) of its initial value; the object is said to be +constrained by its initial value. When not constrained by its initial value, the actual and nominal subtypes +of the object are the same. If its actual subtype is constrained, the object is called a constrained object. + +For an object_declaration without an initialization expression, any initial values for the object or its +subcomponents are determined by the implicit initial values defined for its nominal subtype, as follows: + +• The implicit initial value for an access subtype is the null value of the access type. +• The implicit initial value for a scalar subtype that has the Default_Value aspect specified is the +value of that aspect converted to the nominal subtype (which might raise Constraint_Error — +see 4.6, “Type Conversions”); + +12 + +• The implicit initial (and only) value for each discriminant of a constrained discriminated subtype + +is defined by the subtype. + +13/3 + +• For a (definite) composite subtype, the implicit initial value of each component with a +default_expression is obtained by evaluation of this expression and conversion to the +component's nominal subtype (which might raise Constraint_Error), unless the component is a +discriminant of a constrained subtype (the previous case), or is in an excluded variant (see +3.8.1). For each component that does not have a default_expression, if the composite subtype +has the Default_Component_Value aspect specified, the implicit initial value is the value of that +aspect converted to the component's nominal subtype; otherwise, any implicit initial values are +those determined by the component's nominal subtype. + +14 + +• For a protected or task subtype, there is an implicit component (an entry queue) corresponding to + +each entry, with its implicit initial value being an empty queue. + +15 + +The elaboration of an object_declaration proceeds in the following sequence of steps: + +16/2 + +17 + +18/2 + +19/2 + +20/2 + +1. The subtype_indication, access_definition, array_type_definition, single_task_declaration, or +single_protected_declaration is first elaborated. This creates the nominal subtype (and the +anonymous type in the last four cases). + +2. If the object_declaration includes an initialization expression, the (explicit) initial value is +obtained by evaluating the expression and converting it to the nominal subtype (which might +raise Constraint_Error — see 4.6). + +3. The object is created, and, if there is not an initialization expression, the object is initialized by +default. When an object is initialized by default, any per-object constraints (see 3.8) are +elaborated and any implicit initial values for the object or for its subcomponents are obtained as +determined by the nominal subtype. Any initial values (whether explicit or implicit) are assigned +to the object or to the corresponding subcomponents. As described in 5.2 and 7.6, Initialize and +Adjust procedures can be called. + +This paragraph was deleted. + +For the third step above, evaluations and assignments are performed in an arbitrary order subject to the +following restrictions: + +20.1/2 + +• Assignment to any part of the object is preceded by the evaluation of the value that is to be + +assigned. + +20.2/2 + +• The evaluation of a default_expression that includes the name of a discriminant is preceded by + +the assignment to that discriminant. + +3.3.1 Object Declarations + +13 December 2012 30 + + + Ada Reference Manual — 2012 Edition + +• The evaluation of the default_expression for any component that depends on a discriminant is + +preceded by the assignment to that discriminant. + +• The assignments to any components, including implicit components, not requiring late +initialization precede the initial value evaluations for any components requiring late +initialization; if two components both require late initialization, then assignments to parts of the +component occurring earlier in the order of the component declarations precede the initial value +evaluations of the component occurring later. + +20.3/2 + +20.4/3 + +There is no implicit initial value defined for a scalar subtype unless the Default_Value aspect has been +specified for the type. In the absence of an explicit initialization or the specification of the Default_Value +aspect, a newly created scalar object might have a value that does not belong to its subtype (see 13.9.1 and +H.1). + +NOTES +10 Implicit initial values are not defined for an indefinite subtype, because if an object's nominal subtype is indefinite, an +explicit initial value is required. + +11 As indicated above, a stand-alone object is an object declared by an object_declaration. Similar definitions apply to +“stand-alone constant” and “stand-alone variable.” A subcomponent of an object is not a stand-alone object, nor is an +object that is created by an allocator. An object declared by a loop_parameter_specification, iterator_specification, +parameter_specification, entry_index_specification, choice_parameter_specification, extended_return_statement, or a +formal_object_declaration of mode in out is not considered a stand-alone object. + +12 The type of a stand-alone object cannot be abstract (see 3.9.3). + +Examples + +Example of a multiple object declaration: +-- the multiple object declaration +John, Paul : not null Person_Name := new Person(Sex => M); -- see 3.10.1 +-- is equivalent to the two single object declarations in the order given +John : not null Person_Name := new Person(Sex => M); +Paul : not null Person_Name := new Person(Sex => M); + +Examples of variable declarations: +Count, Sum : Integer; +Size : Integer range 0 .. 10_000 := 0; +Sorted : Boolean := False; +Color_Table : array(1 .. Max) of Color; +Option : Bit_Vector(1 .. 10) := (others => True); +Hello : aliased String := "Hi, world."; +θ, φ : Float range -π .. +π; + +Examples of constant declarations: + +Limit : constant Integer := 10_000; +Low_Limit : constant Integer := Limit/10; +Tolerance : constant Real := Dispersion(1.15); +Hello_Msg : constant access String := Hello'Access; -- see 3.10.2 + +3.3.2 Number Declarations + +A number_declaration declares a named number. + +number_declaration ::= + defining_identifier_list : constant := static_expression; + +Syntax + +21/3 + +22 + +23/3 + +24 + +25 + +26 + +27/2 + +28 + +29/2 + +30 + +31/2 + +32 + +33/2 + +1 + +2 + +31 13 December 2012 + +Object Declarations 3.3.1 + + Ada Reference Manual — 2012 Edition + +3 + +The static_expression given for a number_declaration is expected to be of any numeric type. + +Name Resolution Rules + +4/3 + +The static_expression given for a number declaration shall be a static expression, as defined by subclause +4.9. + +Legality Rules + +5 + +6 + +7 + +8 + +9 + +10/2 + +1/2 + +1.1/2 + +2/2 + +3/2 + +4 + +Static Semantics + +The named number denotes a value of type universal_integer if the type of the static_expression is an +integer type. The named number denotes a value of type universal_real if the type of the static_- +expression is a real type. + +The value denoted by the named number is the value of the static_expression, converted to the +corresponding universal type. + +The elaboration of a number_declaration has no effect. + +Dynamic Semantics + +Examples of number declarations: + +Examples + +Two_Pi : constant := 2.0*Ada.Numerics.Pi; -- a real number (see A.5) +Max : constant := 500; -- an integer number +Max_Line_Size : constant := Max/6; -- the integer 83 +Power_16 : constant := 2**16; -- the integer 65_536 +One, Un, Eins : constant := 1; -- three different names for 1 + +3.4 Derived Types and Classes + +A derived_type_definition defines a derived type (and its first subtype) whose characteristics are derived +from those of a parent type, and possibly from progenitor types. + +A class of types is a set of types that is closed under derivation; that is, if the parent or a progenitor type of +a derived type belongs to a class, then so does the derived type. By saying that a particular group of types +forms a class, we are saying that all derivatives of a type in the set inherit the characteristics that define +that set. The more general term category of types is used for a set of types whose defining characteristics +are not necessarily inherited by derivatives; for example, limited, abstract, and interface are all categories +of types, but not classes of types. + +derived_type_definition ::= + [abstract] [limited] new parent_subtype_indication [[and interface_list] record_extension_part] + +Syntax + +Legality Rules + +The parent_subtype_indication defines the parent subtype; its type is the parent type. The interface_list +defines the progenitor types (see 3.9.4). A derived type has one parent type and zero or more progenitor +types. + +A type shall be completely defined (see 3.11.1) prior to being specified as the parent type in a +derived_type_definition — the full_type_declarations for the parent type and any of its subcomponents +have to precede the derived_type_definition. + +3.3.2 Number Declarations + +13 December 2012 32 + + Ada Reference Manual — 2012 Edition + +If there is a record_extension_part, the derived type is called a record extension of the parent type. A +record_extension_part shall be provided if and only if the parent type is a tagged type. An interface_list +shall be provided only if the parent type is a tagged type. + +If the reserved word limited appears in a derived_type_definition, the parent type shall be a limited type. +If the parent type is a tagged formal type, then in addition to the places where Legality Rules normally +apply (see 12.3), this rule applies also in the private part of an instance of a generic unit. + +Static Semantics + +The first subtype of the derived type is unconstrained if a known_discriminant_part is provided in the +declaration of the derived type, or if the parent subtype is unconstrained. Otherwise, the constraint of the +first subtype corresponds to that of the parent subtype in the following sense: it is the same as that of the +parent subtype except that for a range constraint (implicit or explicit), the value of each bound of its range +is replaced by the corresponding value of the derived type. + +5/2 + +5.1/3 + +6 + +The first subtype of the derived type excludes null (see 3.10) if and only if the parent subtype excludes +null. + +6.1/2 + +The characteristics and implicitly declared primitive subprograms of the derived type are defined as +follows: + +• If the parent type or a progenitor type belongs to a class of types, then the derived type also +belongs to that class. The following sets of types, as well as any higher-level sets composed +from them, are classes in this sense, and hence the characteristics defining these classes are +inherited by derived types from their parent or progenitor types: signed integer, modular integer, +ordinary fixed, decimal fixed, floating point, enumeration, boolean, character, access-to- +constant, general access-to-variable, pool-specific access-to-variable, access-to-subprogram, +array, string, non-array composite, nonlimited, untagged record, tagged, task, protected, and +synchronized tagged. + +• If the parent type is an elementary type or an array type, then the set of possible values of the +derived type is a copy of the set of possible values of the parent type. For a scalar type, the base +range of the derived type is the same as that of the parent type. + +• If the parent type is a composite type other than an array type, then the components, protected + +subprograms, and entries that are declared for the derived type are as follows: + +• The discriminants specified by a new known_discriminant_part, if there is one; otherwise, +each discriminant of the parent type (implicitly declared in the same order with the same +specifications) — in the latter case, the discriminants are said to be inherited, or if unknown +in the parent, are also unknown in the derived type; + +• Each nondiscriminant component, entry, and protected subprogram of the parent type, +implicitly declared in the same order with the same declarations; these components, entries, +and protected subprograms are said to be inherited; + +• Each component declared in a record_extension_part, if any. + + Declarations of components, protected subprograms, and entries, whether implicit or explicit, +occur immediately within the declarative region of the type, in the order indicated above, +following the parent subtype_indication. + +7/3 + +8/2 + +9 + +10 + +11 + +12 + +13 + +14 + +• This paragraph was deleted. +• For each predefined operator of the parent type, there is a corresponding predefined operator of + +15/2 + +16 + +the derived type. + +33 13 December 2012 + +Derived Types and Classes 3.4 + + 17/2 + +18/3 + +19 + +20 + +21 + +22/2 + +23/2 + +24 + +25 + +26 + +27/2 + +Ada Reference Manual — 2012 Edition + +• For each user-defined primitive subprogram (other than a user-defined equality operator — see +below) of the parent type or of a progenitor type that already exists at the place of the +derived_type_definition, there exists a corresponding inherited primitive subprogram of the +derived type with the same defining name. Primitive user-defined equality operators of the +parent type and any progenitor types are also inherited by the derived type, except when the +derived type is a nonlimited record extension, and the inherited operator would have a profile +that is type conformant with the profile of the corresponding predefined equality operator; in this +case, the user-defined equality operator is not inherited, but is rather incorporated into the +implementation of the predefined equality operator of the record extension (see 4.5.2). + + The profile of an inherited subprogram (including an inherited enumeration literal) is obtained +from the profile of the corresponding (user-defined) primitive subprogram of the parent or +progenitor type, after systematic replacement of each subtype of its profile (see 6.1) that is of the +parent or progenitor type, other than those subtypes found in the designated profile of an +access_definition, with a corresponding subtype of the derived type. For a given subtype of the +parent or progenitor type, the corresponding subtype of the derived type is defined as follows: + +• If the declaration of the derived type has neither a known_discriminant_part nor a +record_extension_part, then the corresponding subtype has a constraint that corresponds +(as defined above for the first subtype of the derived type) to that of the given subtype. + +• If the derived type is a record extension, then the corresponding subtype is the first subtype + +of the derived type. + +• If the derived type has a new known_discriminant_part but is not a record extension, then +the corresponding subtype is constrained to those values that when converted to the parent +type belong to the given subtype (see 4.6). + + The same formal parameters have default_expressions in the profile of the inherited +subprogram. Any type mismatch due to the systematic replacement of the parent or progenitor +type by the derived type is handled as part of the normal type conversion associated with +parameter passing — see 6.4.1. + +If a primitive subprogram of the parent or progenitor type is visible at the place of the +derived_type_definition, then the corresponding inherited subprogram is implicitly declared immediately +after the derived_type_definition. Otherwise, the inherited subprogram is implicitly declared later or not at +all, as explained in 7.3.1. + +A derived type can also be defined by a private_extension_declaration (see 7.3) or a formal_derived_- +type_definition (see 12.5.1). Such a derived type is a partial view of the corresponding full or actual type. + +All numeric types are derived types, in that they are implicitly derived from a corresponding root numeric +type (see 3.5.4 and 3.5.6). + +Dynamic Semantics + +The elaboration of a derived_type_definition creates the derived type and its first subtype, and consists of +the elaboration of the subtype_indication and the record_extension_part, if any. If the subtype_- +indication depends on a discriminant, then only those expressions that do not depend on a discriminant are +evaluated. + +For the execution of a call on an inherited subprogram, a call on the corresponding primitive subprogram +of the parent or progenitor type is performed; the normal conversion of each actual parameter to the +subtype of the corresponding formal parameter (see 6.4.1) performs any necessary type conversion as +well. If the result type of the inherited subprogram is the derived type, the result of calling the subprogram +of the parent or progenitor is converted to the derived type, or in the case of a null extension, extended to + +3.4 Derived Types and Classes + +13 December 2012 34 + + Ada Reference Manual — 2012 Edition + +the derived type using the equivalent of an extension_aggregate with the original result as the +ancestor_part and null record as the record_component_association_list. + +NOTES +13 Classes are closed under derivation — any class that contains a type also contains its derivatives. Operations available +for a given class of types are available for the derived types in that class. + +14 Evaluating an inherited enumeration literal is equivalent to evaluating the corresponding enumeration literal of the +parent type, and then converting the result to the derived type. This follows from their equivalence to parameterless +functions. + +15 A generic subprogram is not a subprogram, and hence cannot be a primitive subprogram and cannot be inherited by a +derived type. On the other hand, an instance of a generic subprogram can be a primitive subprogram, and hence can be +inherited. + +16 If the parent type is an access type, then the parent and the derived type share the same storage pool; there is a null +access value for the derived type and it is the implicit initial value for the type. See 3.10. + +17 If the parent type is a boolean type, the predefined relational operators of the derived type deliver a result of the +predefined type Boolean (see 4.5.2). If the parent type is an integer type, the right operand of the predefined +exponentiation operator is of the predefined type Integer (see 4.5.6). + +18 Any discriminants of the parent type are either all inherited, or completely replaced with a new set of discriminants. + +19 For an inherited subprogram, the subtype of a formal parameter of the derived type need not have any value in +common with the first subtype of the derived type. + +20 If the reserved word abstract is given in the declaration of a type, the type is abstract (see 3.9.3). + +21 An interface type that has a progenitor type “is derived from” that type. A derived_type_definition, however, never +defines an interface type. + +22 It is illegal for the parent type of a derived_type_definition to be a synchronized tagged type. + +Examples of derived type declarations: + +Examples + +type Local_Coordinate is new Coordinate; -- two different types +type Midweek is new Day range Tue .. Thu; -- see 3.5.1 +type Counter is new Positive; -- same range as Positive +type Special_Key is new Key_Manager.Key; -- see 7.3.1 + -- the inherited subprograms have the following specifications: + -- procedure Get_Key(K : out Special_Key); + -- function "<"(X,Y : Special_Key) return Boolean; + +28 + +29 + +30 + +31 + +32 + +33 + +34 + +35 + +35.1/2 + +35.2/2 + +36 + +37 + +38 + +3.4.1 Derivation Classes + +In addition to the various language-defined classes of types, types can be grouped into derivation classes. + +1 + +Static Semantics + +A derived type is derived from its parent type directly; it is derived indirectly from any type from which its +parent type is derived. A derived type, interface type, type extension, task type, protected type, or formal +derived type is also derived from every ancestor of each of its progenitor types, if any. The derivation +class of types for a type T (also called the class rooted at T) is the set consisting of T (the root type of the +class) and all types derived from T (directly or indirectly) plus any associated universal or class-wide types +(defined below). + +Every type is either a specific type, a class-wide type, or a universal type. A specific type is one defined +by a type_declaration, a formal_type_declaration, or a full type definition embedded in another construct. +Class-wide and universal types are implicitly defined, to act as representatives for an entire class of types, +as follows: + +2/2 + +3/2 + +35 13 December 2012 + +Derived Types and Classes 3.4 + + Ada Reference Manual — 2012 Edition + +4 + +Class-wide types + +5 + +Class-wide types are defined for (and belong to) each derivation class rooted at a tagged +type (see 3.9). Given a subtype S of a tagged type T, S'Class is the subtype_mark for a +corresponding subtype of the tagged class-wide type T'Class. Such types are called “class- +wide” because when a formal parameter is defined to be of a class-wide type T'Class, an +actual parameter of any type in the derivation class rooted at T is acceptable (see 8.6). + +The set of values for a class-wide type T'Class is the discriminated union of the set of +values of each specific type in the derivation class rooted at T (the tag acts as the implicit +discriminant — see 3.9). Class-wide types have no primitive subprograms of their own. +However, as explained in 3.9.2, operands of a class-wide type T'Class can be used as part of +a dispatching call on a primitive subprogram of the type T. The only components (including +discriminants) of T'Class that are visible are those of T. If S is a first subtype, then S'Class +is a first subtype. + +6/2 + +Universal types + +to + +in + +Universal types are defined for (and belong to) the integer, real, fixed point, and access +classes, and are referred +this standard as respectively, universal_integer, +universal_real, universal_fixed, and universal_access. These are analogous to class-wide +types for these language-defined elementary classes. As with class-wide types, if a formal +parameter is of a universal type, then an actual parameter of any type in the corresponding +class is acceptable. In addition, a value of a universal type (including an integer or real +numeric_literal, or the literal null) is “universal” in that it is acceptable where some +particular type in the class is expected (see 8.6). + +7 + +8 + +9 + +10/2 + +11 + +12 + +13 + +14 + +The set of values of a universal type is the undiscriminated union of the set of values +possible for any definable type in the associated class. Like class-wide types, universal +types have no primitive subprograms of their own. However, their “universality” allows +them to be used as operands with the primitive subprograms of any type in the +corresponding class. + +The integer and real numeric classes each have a specific root type in addition to their universal type, +named respectively root_integer and root_real. + +A class-wide or universal type is said to cover all of the types in its class. A specific type covers only +itself. + +A specific type T2 is defined to be a descendant of a type T1 if T2 is the same as T1, or if T2 is derived +(directly or indirectly) from T1. A class-wide type T2'Class is defined to be a descendant of type T1 if T2 +is a descendant of T1. Similarly, the numeric universal types are defined to be descendants of the root +types of their classes. If a type T2 is a descendant of a type T1, then T1 is called an ancestor of T2. An +ultimate ancestor of a type is an ancestor of that type that is not itself a descendant of any other type. +Every untagged type has a unique ultimate ancestor. + +An inherited component (including an inherited discriminant) of a derived type is inherited from a given +ancestor of the type if the corresponding component was inherited by each derived type in the chain of +derivations going back to the given ancestor. + +NOTES +23 Because operands of a universal type are acceptable to the predefined operators of any type in their class, ambiguity +can result. For universal_integer and universal_real, this potential ambiguity is resolved by giving a preference (see 8.6) +to the predefined operators of the corresponding root types (root_integer and root_real, respectively). Hence, in an +apparently ambiguous expression like + +1 + 4 < 7 + +where each of the literals is of type universal_integer, the predefined operators of root_integer will be preferred over +those of other specific integer types, thereby resolving the ambiguity. + +3.4.1 Derivation Classes + +13 December 2012 36 + + + + + + Ada Reference Manual — 2012 Edition + +3.5 Scalar Types + +Scalar types comprise enumeration types, integer types, and real types. Enumeration types and integer +types are called discrete types; each value of a discrete type has a position number which is an integer +value. Integer types and real types are called numeric types. All scalar types are ordered, that is, all +relational operators are predefined for their values. + +range_constraint ::= range range + +range ::= range_attribute_reference + | simple_expression .. simple_expression + +Syntax + +A range has a lower bound and an upper bound and specifies a subset of the values of some scalar type +(the type of the range). A range with lower bound L and upper bound R is described by “L .. R”. If R is +less than L, then the range is a null range, and specifies an empty set of values. Otherwise, the range +specifies the values of the type from the lower bound to the upper bound, inclusive. A value belongs to a +range if it is of the type of the range, and is in the subset of values specified by the range. A value satisfies +a range constraint if it belongs to the associated range. One range is included in another if all values that +belong to the first range also belong to the second. + +Name Resolution Rules + +For a subtype_indication containing a range_constraint, either directly or as part of some other +scalar_constraint, the type of the range shall resolve to that of the type determined by the subtype_mark +of the subtype_indication. For a range of a given type, the simple_expressions of the range (likewise, +the simple_expressions of the equivalent range for a range_attribute_reference) are expected to be of +the type of the range. + +Static Semantics + +The base range of a scalar type is the range of finite values of the type that can be represented in every +unconstrained object of the type; it is also the range supported at a minimum for intermediate values +during the evaluation of expressions involving predefined operators of the type. + +A constrained scalar subtype is one to which a range constraint applies. The range of a constrained scalar +subtype is the range associated with the range constraint of the subtype. The range of an unconstrained +scalar subtype is the base range of its type. + +Dynamic Semantics + +A range is compatible with a scalar subtype if and only if it is either a null range or each bound of the +range belongs to the range of the subtype. A range_constraint is compatible with a scalar subtype if and +only if its range is compatible with the subtype. + +The elaboration of a range_constraint consists of the evaluation of the range. The evaluation of a range +determines a lower bound and an upper bound. If simple_expressions are given to specify bounds, the +evaluation of the range evaluates these simple_expressions in an arbitrary order, and converts them to the +type of the range. If a range_attribute_reference is given, the evaluation of the range consists of the +evaluation of the range_attribute_reference. + +1 + +2 + +3 + +4 + +5 + +6 + +7 + +8 + +9 + +37 13 December 2012 + +Scalar Types 3.5 + + Ada Reference Manual — 2012 Edition + +Attributes + +For every scalar subtype S, the following attributes are defined: + +S'First + +S'First denotes the lower bound of the range of S. The value of this attribute is of the type +of S. + +10 + +11 + +12 + +13 + +S'Last + +S'Last denotes the upper bound of the range of S. The value of this attribute is of the type of +S. + +14 + +15 + +16 + +17 + +18 + +19 + +20 + +21 + +22 + +23 + +24 + +25 + +26 + +27 + +S'Range + +S'Range is equivalent to the range S'First .. S'Last. + +S'Base + +S'Base denotes an unconstrained subtype of the type of S. This unconstrained subtype is +called the base subtype of the type. + +S'Min + +S'Min denotes a function with the following specification: + +function S'Min(Left, Right : S'Base) + return S'Base + +The function returns the lesser of the values of the two parameters. + +S'Max + +S'Max denotes a function with the following specification: + +function S'Max(Left, Right : S'Base) + return S'Base + +The function returns the greater of the values of the two parameters. + +S'Succ + +S'Succ denotes a function with the following specification: + +function S'Succ(Arg : S'Base) + return S'Base + +For an enumeration type, the function returns the value whose position number is one more +than that of the value of Arg; Constraint_Error is raised if there is no such value of the type. +For an integer type, the function returns the result of adding one to the value of Arg. For a +fixed point type, the function returns the result of adding small to the value of Arg. For a +floating point type, the function returns the machine number (as defined in 3.5.7) +immediately above the value of Arg; Constraint_Error is raised if there is no such machine +number. + +S'Pred + +S'Pred denotes a function with the following specification: + +function S'Pred(Arg : S'Base) + return S'Base + +For an enumeration type, the function returns the value whose position number is one less +than that of the value of Arg; Constraint_Error is raised if there is no such value of the type. +For an integer type, the function returns the result of subtracting one from the value of Arg. +For a fixed point type, the function returns the result of subtracting small from the value of +Arg. For a floating point type, the function returns the machine number (as defined in 3.5.7) +immediately below the value of Arg; Constraint_Error is raised if there is no such machine +number. + +27.1/2 + +S'Wide_Wide_Image + +27.2/2 + +27.3/2 + +27.4/2 + +S'Wide_Wide_Image denotes a function with the following specification: + +function S'Wide_Wide_Image(Arg : S'Base) + return Wide_Wide_String + +The function returns an image of the value of Arg, that is, a sequence of characters +representing the value in display form. The lower bound of the result is one. + +The image of an integer value is the corresponding decimal literal, without underlines, +leading zeros, exponent, or trailing spaces, but with a single leading character that is either +a minus sign or a space. + +3.5 Scalar Types + +13 December 2012 38 + + + + + + + + + Ada Reference Manual — 2012 Edition + +The image of an enumeration value is either the corresponding identifier in upper case or +the corresponding character literal (including the two apostrophes); neither leading nor +trailing spaces are included. For a nongraphic character (a value of a character type that +has no enumeration literal associated with it), the result is a corresponding language- +defined name in upper case (for example, the image of the nongraphic character identified +as nul is “NUL” — the quotes are not part of the image). + +The image of a floating point value is a decimal real literal best approximating the value +(rounded away from zero if halfway between) with a single leading character that is either a +minus sign or a space, a single digit (that is nonzero unless the value is zero), a decimal +point, S'Digits–1 (see 3.5.8) digits after the decimal point (but one if S'Digits is one), an +upper case E, the sign of the exponent (either + or –), and two or more digits (with leading +zeros if necessary) representing the exponent. If S'Signed_Zeros is True, then the leading +character is a minus sign for a negatively signed zero. + +27.5/2 + +27.6/2 + +The image of a fixed point value is a decimal real literal best approximating the value +(rounded away from zero if halfway between) with a single leading character that is either a +minus sign or a space, one or more digits before the decimal point (with no redundant +leading zeros), a decimal point, and S'Aft (see 3.5.10) digits after the decimal point. + +27.7/2 + +S'Wide_Image S'Wide_Image denotes a function with the following specification: + +function S'Wide_Image(Arg : S'Base) + return Wide_String + +The function returns an image of the value of Arg as a Wide_String. The lower bound of the +result is one. The image has the same sequence of graphic characters as defined for +S'Wide_Wide_Image if all the graphic characters are defined in Wide_Character; +otherwise, the sequence of characters is implementation defined (but no shorter than that of +S'Wide_Wide_Image for the same value of Arg). + +Paragraphs 31 through 34 were moved to Wide_Wide_Image. + +S'Image + +S'Image denotes a function with the following specification: + +function S'Image(Arg : S'Base) + return String + +The function returns an image of the value of Arg as a String. The lower bound of the result +is one. The image has the same sequence of graphic characters as that defined for +S'Wide_Wide_Image if all the graphic characters are defined in Character; otherwise, the +sequence of characters +that of +S'Wide_Wide_Image for the same value of Arg). + +implementation defined (but no shorter + +than + +is + +S'Wide_Wide_Width + +S'Wide_Wide_Width denotes the maximum length of a Wide_Wide_String returned by +S'Wide_Wide_Image over all values of the subtype S. It denotes zero for a subtype that has +a null range. Its type is universal_integer. + +S'Wide_Width + +S'Wide_Width denotes the maximum length of a Wide_String returned by S'Wide_Image +over all values of the subtype S. It denotes zero for a subtype that has a null range. Its type +is universal_integer. + +S'Width + +S'Width denotes the maximum length of a String returned by S'Image over all values of the +subtype S. It denotes zero for a subtype that has a null range. Its type is universal_integer. + +S'Wide_Wide_Value + +S'Wide_Wide_Value denotes a function with the following specification: + +function S'Wide_Wide_Value(Arg : Wide_Wide_String) + return S'Base + +39 13 December 2012 + +Scalar Types 3.5 + +28 + +29 + +30/3 + +35 + +36 + +37/3 + +37.1/2 + +38 + +39 + +39.1/2 + +39.2/2 + + + + + + + + + + + Ada Reference Manual — 2012 Edition + +39.3/2 + +39.4/3 + +39.5/3 + +39.6/2 + +39.7/2 + +39.8/2 + +39.9/2 + +39.10/2 + +39.11/2 + +39.12/3 + +This function returns a value given an image of the value as a Wide_Wide_String, ignoring +any leading or trailing spaces. + +For the evaluation of a call on S'Wide_Wide_Value for an enumeration subtype S, if the +sequence of characters of the parameter (ignoring leading and trailing spaces) has the +syntax of an enumeration literal and if it corresponds to a literal of the type of S (or +corresponds to the result of S'Wide_Wide_Image for a nongraphic character of the type), +the result is the corresponding enumeration value; otherwise, Constraint_Error is raised. + +For the evaluation of a call on S'Wide_Wide_Value for an integer subtype S, if the +sequence of characters of the parameter (ignoring leading and trailing spaces) has the +syntax of an integer literal, with an optional leading sign character (plus or minus for a +signed type; only plus for a modular type), and the corresponding numeric value belongs to +the base range of the type of S, then that value is the result; otherwise, Constraint_Error is +raised. + +For the evaluation of a call on S'Wide_Wide_Value for a real subtype S, if the sequence of +characters of the parameter (ignoring leading and trailing spaces) has the syntax of one of +the following: + +• numeric_literal +• numeral.[exponent] +• +• base#based_numeral.#[exponent] +• base#.based_numeral#[exponent] + +.numeral[exponent] + +with an optional leading sign character (plus or minus), and if the corresponding numeric +value belongs to the base range of the type of S, then that value is the result; otherwise, +Constraint_Error is raised. The sign of a zero value is preserved (positive if none has been +specified) if S'Signed_Zeros is True. + +40 + +S'Wide_Value + +41 + +42 + +43/3 + +52 + +53 + +54 + +55/3 + +S'Wide_Value denotes a function with the following specification: + +function S'Wide_Value(Arg : Wide_String) + return S'Base + +This function returns a value given an image of the value as a Wide_String, ignoring any +leading or trailing spaces. + +For the evaluation of a call on S'Wide_Value for an enumeration subtype S, if the sequence +of characters of the parameter (ignoring leading and trailing spaces) has the syntax of an +enumeration literal and if it corresponds to a literal of the type of S (or corresponds to the +result of S'Wide_Image for a value of the type), the result is the corresponding enumeration +value; otherwise, Constraint_Error is raised. For a numeric subtype S, the evaluation of a +call on S'Wide_Value with Arg of type Wide_String is equivalent to a call on +S'Wide_Wide_Value for a corresponding Arg of type Wide_Wide_String. + +Paragraphs 44 through 51 were moved to Wide_Wide_Value. + +S'Value + +S'Value denotes a function with the following specification: + +function S'Value(Arg : String) + return S'Base + +This function returns a value given an image of the value as a String, ignoring any leading +or trailing spaces. + +For the evaluation of a call on S'Value for an enumeration subtype S, if the sequence of +characters of the parameter (ignoring leading and trailing spaces) has the syntax of an + +3.5 Scalar Types + +13 December 2012 40 + + + + + + + + + + + + + Ada Reference Manual — 2012 Edition + +enumeration literal and if it corresponds to a literal of the type of S (or corresponds to the +result of S'Image for a value of the type), the result is the corresponding enumeration value; +otherwise, Constraint_Error is raised. For a numeric subtype S, the evaluation of a call on +S'Value with Arg of type String is equivalent to a call on S'Wide_Wide_Value for a +corresponding Arg of type Wide_Wide_String. + +Implementation Permissions + +An implementation may extend the Wide_Wide_Value, Wide_Value, Value, Wide_Wide_Image, +Wide_Image, and Image attributes of a floating point type to support special values such as infinities and +NaNs. + +56/2 + +An implementation may extend the Wide_Wide_Value, Wide_Value, and Value attributes of a character +type to accept strings of the form “Hex_hhhhhhhh” (ignoring case) for any character (not just the ones for +which Wide_Wide_Image would produce that form — see 3.5.2), as well as three-character strings of the +form “'X'”, where X is any character, including nongraphic characters. + +56.1/3 + +For a scalar type, the following language-defined representation aspect may be specified with an +aspect_specification (see 13.1.1): + +Static Semantics + +Default_Value + +This aspect shall be specified by a static expression, and that expression shall be explicit, +even if the aspect has a boolean type. Default_Value shall be specified only on a +full_type_declaration. + +56.2/3 + +56.3/3 + +If a derived type with no primitive subprograms inherits a boolean Default_Value aspect, the aspect may +be specified to have any value for the derived type. + +56.4/3 + +The expected type for the expression specified for the Default_Value aspect is the type defined by the +full_type_declaration on which it appears. + +56.5/3 + +Name Resolution Rules + +NOTES +24 The evaluation of S'First or S'Last never raises an exception. If a scalar subtype S has a nonnull range, S'First and +S'Last belong to this range. These values can, for example, always be assigned to a variable of subtype S. + +25 For a subtype of a scalar type, the result delivered by the attributes Succ, Pred, and Value might not belong to the +subtype; similarly, the actual parameters of the attributes Succ, Pred, and Image need not belong to the subtype. + +26 For any value V (including any nongraphic character) of an enumeration subtype S, S'Value(S'Image(V)) equals V, as +do S'Wide_Value(S'Wide_Image(V)) and S'Wide_Wide_Value(S'Wide_Wide_Image(V)). None of these expressions ever +raise Constraint_Error. + +Examples + +Examples of ranges: +-10 .. 10 +X .. X + 1 +0.0 .. 2.0*Pi +Red .. Green -- see 3.5.1 +1 .. 0 -- a null range +Table'Range -- a range attribute reference (see 3.6) + +Examples of range constraints: + +range -999.0 .. +999.0 +range S'First+1 .. S'Last-1 + +57 + +58 + +59 + +60 + +61 + +62 + +63 + +41 13 December 2012 + +Scalar Types 3.5 + + + Ada Reference Manual — 2012 Edition + +3.5.1 Enumeration Types + +An enumeration_type_definition defines an enumeration type. + +Syntax + +enumeration_type_definition ::= + (enumeration_literal_specification {, enumeration_literal_specification}) + +enumeration_literal_specification ::= defining_identifier | defining_character_literal + +defining_character_literal ::= character_literal + +1 + +2 + +3 + +4 + +5/3 + +The defining_identifiers +enumeration_type_definition shall be distinct. + +in upper case and + +the defining_character_literals + +listed + +in an + +Legality Rules + +6/3 + +Each enumeration_literal_specification is the explicit declaration of the corresponding enumeration +literal: it declares a parameterless function, whose defining name is the defining_identifier or defining_- +character_literal, and whose result subtype is the base subtype of the enumeration type. + +Static Semantics + +7 + +8 + +9 + +10 + +11 + +12 + +13 + +14 + +Each enumeration literal corresponds to a distinct value of the enumeration type, and to a distinct position +number. The position number of the value of the first listed enumeration literal is zero; the position +number of the value of each subsequent enumeration literal is one more than that of its predecessor in the +list. + +The predefined order relations between values of the enumeration type follow the order of corresponding +position numbers. + +If the same defining_identifier or defining_character_literal is specified in more than one enumeration_- +type_definition, the corresponding enumeration literals are said to be overloaded. At any place where an +overloaded enumeration literal occurs in the text of a program, the type of the enumeration literal has to be +determinable from the context (see 8.6). + +Dynamic Semantics + +The elaboration of an enumeration_type_definition creates the enumeration type and its first subtype, +which is constrained to the base range of the type. + +When called, the parameterless function associated with an enumeration literal returns the corresponding +value of the enumeration type. + +NOTES +27 If an enumeration literal occurs in a context that does not otherwise suffice to determine the type of the literal, then +qualification by the name of the enumeration type is one way to resolve the ambiguity (see 4.7). + +Examples of enumeration types and subtypes: + +Examples + +type Day is (Mon, Tue, Wed, Thu, Fri, Sat, Sun); +type Suit is (Clubs, Diamonds, Hearts, Spades); +type Gender is (M, F); +type Level is (Low, Medium, Urgent); +type Color is (White, Red, Yellow, Green, Blue, Brown, Black); +type Light is (Red, Amber, Green); -- Red and Green are overloaded + +3.5.1 Enumeration Types + +13 December 2012 42 + + Ada Reference Manual — 2012 Edition + +type Hexa is ('A', 'B', 'C', 'D', 'E', 'F'); +type Mixed is ('A', 'B', '*', B, None, '?', '%'); +subtype Weekday is Day range Mon .. Fri; +subtype Major is Suit range Hearts .. Spades; +subtype Rainbow is Color range Red .. Blue; -- the Color Red, not the Light + +3.5.2 Character Types + +Static Semantics + +An enumeration type is said to be a character type if at least one of its enumeration literals is a +character_literal. + +The predefined type Character is a character type whose values correspond to the 256 code points of Row +00 (also known as Latin-1) of the ISO/IEC 10646:2011 Basic Multilingual Plane (BMP). Each of the +graphic characters of Row 00 of the BMP has a corresponding character_literal in Character. Each of the +nongraphic characters of Row 00 has a corresponding language-defined name, which is not usable as an +enumeration literal, but which is usable with the attributes Image, Wide_Image, Wide_Wide_Image, +Value, Wide_Value, and Wide_Wide_Value; these names are given in the definition of type Character in +A.1, “The Package Standard”, but are set in italics. + +The predefined type Wide_Character is a character type whose values correspond to the 65536 code points +of the ISO/IEC 10646:2011 Basic Multilingual Plane (BMP). Each of the graphic characters of the BMP +has a corresponding character_literal in Wide_Character. The first 256 values of Wide_Character have the +same character_literal or language-defined name as defined for Character. Each of the graphic_characters +has a corresponding character_literal. + +The predefined type Wide_Wide_Character is a character type whose values correspond to the +2147483648 code points of the ISO/IEC 10646:2011 character set. Each of the graphic_characters has a +of +corresponding +Wide_Wide_Character have the same character_literal or language-defined name as defined for +Wide_Character. + +in Wide_Wide_Character. The + +character_literal + +values + +65536 + +first + +The characters whose code point is larger than 16#FF# and which are not graphic_characters have +language-defined names which are formed by appending to the string "Hex_" the representation of their +code point in hexadecimal as eight extended digits. As with other language-defined names, these names +are usable only with the attributes (Wide_)Wide_Image and (Wide_)Wide_Value; they are not usable as +enumeration literals. + +Paragraphs 6 and 7 were deleted. + +NOTES +28 The language-defined library package Characters.Latin_1 (see A.3.3) includes the declaration of constants denoting +control characters, lower case characters, and special characters of the predefined type Character. + +29 A conventional character set such as EBCDIC can be declared as a character type; the internal codes of the characters +can be specified by an enumeration_representation_clause as explained in subclause 13.4. + +Example of a character type: + +type Roman_Digit is ('I', 'V', 'X', 'L', 'C', 'D', 'M'); + +Examples + +43 13 December 2012 + +Enumeration Types 3.5.1 + +15 + +16 + +1 + +2/3 + +3/3 + +4/3 + +5/3 + +8 + +9/3 + +10 + +11 + + Ada Reference Manual — 2012 Edition + +3.5.3 Boolean Types + +1 + +1 + +2 + +3 + +4 + +5 + +6 + +7 + +8 + +9 + +10 + +11 + +There is a predefined enumeration type named Boolean, declared in the visible part of package Standard. It +has the two enumeration literals False and True ordered with the relation False < True. Any descendant of +the predefined type Boolean is called a boolean type. + +Static Semantics + +3.5.4 Integer Types + +An integer_type_definition defines an integer type; it defines either a signed integer type, or a modular +integer type. The base range of a signed integer type includes at least the values of the specified range. A +modular type is an integer type with all arithmetic modulo a specified positive modulus; such a type +corresponds to an unsigned type with wrap-around semantics. + +integer_type_definition ::= signed_integer_type_definition | modular_type_definition + +signed_integer_type_definition ::= range static_simple_expression .. static_simple_expression + +modular_type_definition ::= mod static_expression + +Syntax + +Each simple_expression in a signed_integer_type_definition is expected to be of any integer type; they +need not be of the same type. The expression in a modular_type_definition is likewise expected to be of +any integer type. + +Name Resolution Rules + +Legality Rules + +The simple_expressions of a signed_integer_type_definition shall be static, and their values shall be in +the range System.Min_Int .. System.Max_Int. + +The expression of a modular_type_definition shall be static, and its value (the modulus) shall be positive, +and shall be no greater than System.Max_Binary_Modulus if a power of 2, or no greater than +System.Max_Nonbinary_Modulus if not. + +Static Semantics + +The set of values for a signed integer type is the (infinite) set of mathematical integers, though only values +of the base range of the type are fully supported for run-time operations. The set of values for a modular +integer type are the values from 0 to one less than the modulus, inclusive. + +A signed_integer_type_definition defines an integer type whose base range includes at least the values of +the simple_expressions and is symmetric about zero, excepting possibly an extra negative value. A +signed_integer_type_definition also defines a constrained first subtype of the type, with a range whose +bounds are given by the values of the simple_expressions, converted to the type being defined. + +A modular_type_definition defines a modular type whose base range is from zero to one less than the +given modulus. A modular_type_definition also defines a constrained first subtype of the type with a +range that is the same as the base range of the type. + +There is a predefined signed integer subtype named Integer, declared in the visible part of package +Standard. It is constrained to the base range of its type. + +3.5.3 Boolean Types + +13 December 2012 44 + + Ada Reference Manual — 2012 Edition + +Integer has two predefined subtypes, declared in the visible part of package Standard: + +subtype Natural is Integer range 0 .. Integer'Last; +subtype Positive is Integer range 1 .. Integer'Last; + +A type defined by an integer_type_definition is implicitly derived from root_integer, an anonymous +predefined (specific) integer type, whose base range is System.Min_Int .. System.Max_Int. However, the +base range of the new type is not inherited from root_integer, but is instead determined by the range or +modulus specified by the integer_type_definition. Integer literals are all of the type universal_integer, the +universal type (see 3.4.1) for the class rooted at root_integer, allowing their use with the operations of any +integer type. + +The position number of an integer value is equal to the value. + +For every modular subtype S, the following attributes are defined: + +S'Mod + +S'Mod denotes a function with the following specification: + +function S'Mod (Arg : universal_integer) + return S'Base + +This function returns Arg mod S'Modulus, as a value of the type of S. + +S'Modulus + +S'Modulus yields the modulus of the type of S, as a value of the type universal_integer. + +The elaboration of an integer_type_definition creates the integer type and its first subtype. + +Dynamic Semantics + +For a modular type, if the result of the execution of a predefined operator (see 4.5) is outside the base +range of the type, the result is reduced modulo the modulus of the type to a value that is within the base +range of the type. + +For a signed integer type, the exception Constraint_Error is raised by the execution of an operation that +cannot deliver the correct result because it is outside the base range of the type. For any integer type, +Constraint_Error is raised by the operators "/", "rem", and "mod" if the right operand is zero. + +In an implementation, the range of Integer shall include the range –2**15+1 .. +2**15–1. + +Implementation Requirements + +If Long_Integer is predefined for an implementation, then its range shall include the range –2**31+1 .. ++2**31–1. + +System.Max_Binary_Modulus shall be at least 2**16. + +Implementation Permissions + +For the execution of a predefined operation of a signed integer type, the implementation need not raise +Constraint_Error if the result is outside the base range of the type, so long as the correct result is produced. + +An implementation may provide additional predefined signed integer types, declared in the visible part of +Standard, whose first subtypes have names of the form Short_Integer, Long_Integer, Short_Short_Integer, +Long_Long_Integer, etc. Different predefined integer types are allowed to have the same base range. +However, the range of Integer should be no wider than that of Long_Integer. Similarly, the range of +Short_Integer (if provided) should be no wider than Integer. Corresponding recommendations apply to any +other predefined integer types. There need not be a named integer type corresponding to each distinct base +range supported by an implementation. The range of each first subtype should be the base range of its +type. + +12 + +13 + +14 + +15 + +16/2 + +16.1/2 + +16.2/2 + +16.3/2 + +17 + +18 + +19 + +20 + +21 + +22 + +23 + +24 + +25 + +45 13 December 2012 + +Integer Types 3.5.4 + + + Ada Reference Manual — 2012 Edition + +26 + +An implementation may provide nonstandard integer types, descendants of root_integer that are declared +outside of the specification of package Standard, which need not have all the standard characteristics of a +type defined by an integer_type_definition. For example, a nonstandard integer type might have an +asymmetric base range or it might not be allowed as an array or loop index (a very long integer). Any type +descended from a nonstandard integer type is also nonstandard. An implementation may place arbitrary +restrictions on the use of such types; it is implementation defined whether operators that are predefined for +“any integer type” are defined for a particular nonstandard integer type. In any case, such types are not +permitted as explicit_generic_actual_parameters for formal scalar types — see 12.5.2. + +27 + +For a one's complement machine, the high bound of the base range of a modular type whose modulus is +one less than a power of 2 may be equal to the modulus, rather than one less than the modulus. It is +implementation defined for which powers of 2, if any, this permission is exercised. + +27.1/1 + +For a one's complement machine, implementations may support nonbinary modulus values greater than +System.Max_Nonbinary_Modulus. It is implementation defined which specific values greater than +System.Max_Nonbinary_Modulus, if any, are supported. + +28 + +29 + +30 + +31 + +32 + +33 + +34 + +35 + +36 + +Implementation Advice + +An implementation should support Long_Integer in addition to Integer if the target machine supports 32- +bit (or longer) arithmetic. No other named integer subtypes are recommended for package Standard. +Instead, appropriate named integer subtypes should be provided in the library package Interfaces (see B.2). + +An implementation for a two's complement machine should support modular types with a binary modulus +up to System.Max_Int*2+2. An implementation should support a nonbinary modulus up to Integer'Last. + +NOTES +30 Integer literals are of the anonymous predefined integer type universal_integer. Other integer types have no literals. +However, the overload resolution rules (see 8.6, “The Context of Overload Resolution”) allow expressions of the type +universal_integer whenever an integer type is expected. + +31 The same arithmetic operators are predefined for all signed integer types defined by a signed_integer_type_definition +(see 4.5, “Operators and Expression Evaluation”). For modular types, these same operators are predefined, plus bit-wise +logical operators (and, or, xor, and not). In addition, for the unsigned types declared in the language-defined package +Interfaces (see B.2), functions are defined that provide bit-wise shifting and rotating. + +32 Modular types match a generic_formal_parameter_declaration of the form "type T is mod <>;"; signed integer types +match "type T is range <>;" (see 12.5.2). + +Examples of integer types and subtypes: + +Examples + +type Page_Num is range 1 .. 2_000; +type Line_Size is range 1 .. Max_Line_Size; +subtype Small_Int is Integer range -10 .. 10; +subtype Column_Ptr is Line_Size range 1 .. 10; +subtype Buffer_Size is Integer range 0 .. Max; +type Byte is mod 256; -- an unsigned byte +type Hash_Index is mod 97; -- modulus is prime + +3.5.4 Integer Types + +13 December 2012 46 + + Ada Reference Manual — 2012 Edition + +3.5.5 Operations of Discrete Types + +For every discrete subtype S, the following attributes are defined: + +S'Pos + +S'Pos denotes a function with the following specification: + +Static Semantics + +function S'Pos(Arg : S'Base) + return universal_integer + +This function returns the position number of the value of Arg, as a value of type +universal_integer. + +S'Val + +S'Val denotes a function with the following specification: + +function S'Val(Arg : universal_integer) + return S'Base + +This function returns a value of the type of S whose position number equals the value of +Arg. For the evaluation of a call on S'Val, if there is no value in the base range of its type +with the given position number, Constraint_Error is raised. + +For every static discrete subtype S for which there exists at least one value belonging to S that satisfies any +predicate of S, the following attributes are defined: + +S'First_Valid + +S'Last_Valid + +S'First_Valid denotes the smallest value that belongs to S and satisfies the predicate of S. +The value of this attribute is of the type of S. + +1 + +2 + +3 + +4 + +5 + +6 + +7 + +7.1/3 + +7.2/3 + +7.3/3 + +S'Last_Valid denotes the largest value that belongs to S and satisfies the predicate of S. The +value of this attribute is of the type of S. + +First_Valid and Last_Valid attribute_references are always static expressions. Any explicit predicate of S +can only have been specified by a Static_Predicate aspect. + +7.4/3 + +Implementation Advice + +For the evaluation of a call on S'Pos for an enumeration subtype, if the value of the operand does not +correspond to the internal code for any enumeration literal of its type (perhaps due to an uninitialized +variable), then the implementation should raise Program_Error. This is particularly important for +enumeration types with noncontiguous internal codes specified by an enumeration_representation_- +clause. + +NOTES +33 Indexing and loop iteration use values of discrete types. + +34 The predefined operations of a discrete type include the assignment operation, qualification, the membership tests, and +the relational operators; for a boolean type they include the short-circuit control forms and the logical operators; for an +integer type they include type conversion to and from other numeric types, as well as the binary and unary adding +operators – and +, the multiplying operators, the unary operator abs, and the exponentiation operator. The assignment +operation is described in 5.2. The other predefined operations are described in Clause 4. + +35 As for all types, objects of a discrete type have Size and Address attributes (see 13.3). + +36 For a subtype of a discrete type, the result delivered by the attribute Val might not belong to the subtype; similarly, the +actual parameter of the attribute Pos need not belong to the subtype. The following relations are satisfied (in the absence +of an exception) by these attributes: + S'Val(S'Pos(X)) = X + S'Pos(S'Val(N)) = N + +8 + +9 + +10/3 + +11 + +12 + +13 + +47 13 December 2012 + +Operations of Discrete Types 3.5.5 + + + + + + 14 + +15 + +16 + +17 + +1 + +2 + +3 + +4 + +5 + +6 + +7/2 + +8 + +Ada Reference Manual — 2012 Edition + +Examples of attributes of discrete subtypes: + +Examples + +-- For the types and subtypes declared in subclause 3.5.1 the following hold: +-- Color'First = White, Color'Last = Black +-- Rainbow'First = Red, Rainbow'Last = Blue + +-- Color'Succ(Blue) = Rainbow'Succ(Blue) = Brown +-- Color'Pos(Blue) = Rainbow'Pos(Blue) = 4 +-- Color'Val(0) = Rainbow'Val(0) = White + +3.5.6 Real Types + +Real types provide approximations to the real numbers, with relative bounds on errors for floating point +types, and with absolute bounds for fixed point types. + +real_type_definition ::= + floating_point_definition | fixed_point_definition + +Syntax + +Static Semantics + +A type defined by a real_type_definition is implicitly derived from root_real, an anonymous predefined +(specific) real type. Hence, all real types, whether floating point or fixed point, are in the derivation class +rooted at root_real. + +Real literals are all of the type universal_real, the universal type (see 3.4.1) for the class rooted at +root_real, allowing their use with the operations of any real type. Certain multiplying operators have a +result type of universal_fixed (see 4.5.5), the universal type for the class of fixed point types, allowing the +result of the multiplication or division to be used where any specific fixed point type is expected. + +The elaboration of a real_type_definition consists of the elaboration of the floating_point_definition or the +fixed_point_definition. + +Dynamic Semantics + +An implementation shall perform the run-time evaluation of a use of a predefined operator of root_real +with an accuracy at least as great as that of any floating point type definable by a floating_point_definition. + +Implementation Requirements + +Implementation Permissions + +For the execution of a predefined operation of a real type, the implementation need not raise +Constraint_Error if the result is outside the base range of the type, so long as the correct result is produced, +or the Machine_Overflows attribute of the type is False (see G.2). + +An implementation may provide nonstandard real types, descendants of root_real that are declared +outside of the specification of package Standard, which need not have all the standard characteristics of a +type defined by a real_type_definition. For example, a nonstandard real type might have an asymmetric or +unsigned base range, or its predefined operations might wrap around or “saturate” rather than overflow +(modular or saturating arithmetic), or it might not conform to the accuracy model (see G.2). Any type +descended from a nonstandard real type is also nonstandard. An implementation may place arbitrary +restrictions on the use of such types; it is implementation defined whether operators that are predefined for +“any real type” are defined for a particular nonstandard real type. In any case, such types are not permitted +as explicit_generic_actual_parameters for formal scalar types — see 12.5.2. + +3.5.5 Operations of Discrete Types + +13 December 2012 48 + + Ada Reference Manual — 2012 Edition + +NOTES +37 As stated, real literals are of the anonymous predefined real type universal_real. Other real types have no literals. +However, the overload resolution rules (see 8.6) allow expressions of the type universal_real whenever a real type is +expected. + +3.5.7 Floating Point Types + +For floating point types, the error bound is specified as a relative precision by giving the required +minimum number of significant decimal digits. + +Syntax + +floating_point_definition ::= + digits static_expression [real_range_specification] + +real_range_specification ::= + range static_simple_expression .. static_simple_expression + +Name Resolution Rules + +The requested decimal precision, which is the minimum number of significant decimal digits required for +the floating point type, is specified by the value of the expression given after the reserved word digits. +This expression is expected to be of any integer type. + +Each simple_expression of a real_range_specification is expected to be of any real type; the types need +not be the same. + +Legality Rules + +The requested decimal precision shall be specified by a static expression whose value is positive and no +greater than System.Max_Base_Digits. Each simple_expression of a real_range_specification shall also +be static. If the real_range_specification is omitted, the requested decimal precision shall be no greater +than System.Max_Digits. + +A floating_point_definition is illegal if the implementation does not support a floating point type that +satisfies the requested decimal precision and range. + +Static Semantics + +The set of values for a floating point type is the (infinite) set of rational numbers. The machine numbers of +a floating point type are the values of the type that can be represented exactly in every unconstrained +variable of the type. The base range (see 3.5) of a floating point type is symmetric around zero, except that +it can include some extra negative values in some implementations. + +The base decimal precision of a floating point type is the number of decimal digits of precision +representable in objects of the type. The safe range of a floating point type is that part of its base range for +which the accuracy corresponding to the base decimal precision is preserved by all predefined operations. + +9 + +1 + +2 + +3 + +4 + +5 + +6 + +7 + +8 + +9 + +A floating_point_definition defines a floating point type whose base decimal precision is no less than the +requested decimal precision. If a real_range_specification is given, the safe range of the floating point +type (and hence, also its base range) includes at least the values of the simple expressions given in the +real_range_specification. If a real_range_specification is not given, the safe (and base) range of the type +includes at least the values of the range –10.0**(4*D) .. +10.0**(4*D) where D is the requested decimal +precision. The safe range might include other values as well. The attributes Safe_First and Safe_Last give +the actual bounds of the safe range. + +10 + +49 13 December 2012 + +Real Types 3.5.6 + + Ada Reference Manual — 2012 Edition + +11 + +A floating_point_definition also defines a first subtype of the type. If a real_range_specification is given, +then the subtype is constrained to a range whose bounds are given by a conversion of the values of the +simple_expressions of the real_range_specification to the type being defined. Otherwise, the subtype is +unconstrained. + +12 + +There is a predefined, unconstrained, floating point subtype named Float, declared in the visible part of +package Standard. + +13 + +The elaboration of a floating_point_definition creates the floating point type and its first subtype. + +Dynamic Semantics + +Implementation Requirements + +In an implementation that supports floating point types with 6 or more digits of precision, the requested +decimal precision for Float shall be at least 6. + +If Long_Float is predefined for an implementation, then its requested decimal precision shall be at least +11. + +Implementation Permissions + +An implementation is allowed to provide additional predefined floating point types, declared in the visible +part of Standard, whose (unconstrained) first subtypes have names of the form Short_Float, Long_Float, +Short_Short_Float, Long_Long_Float, etc. Different predefined floating point types are allowed to have +the same base decimal precision. However, the precision of Float should be no greater than that of +Long_Float. Similarly, the precision of Short_Float (if provided) should be no greater than Float. +Corresponding recommendations apply to any other predefined floating point types. There need not be a +named floating point type corresponding to each distinct base decimal precision supported by an +implementation. + +Implementation Advice + +An implementation should support Long_Float in addition to Float if the target machine supports 11 or +more digits of precision. No other named floating point subtypes are recommended for package Standard. +Instead, appropriate named floating point subtypes should be provided in the library package Interfaces +(see B.2). + +NOTES +38 If a floating point subtype is unconstrained, then assignments to variables of the subtype involve only +Overflow_Checks, never Range_Checks. + +Examples of floating point types and subtypes: + +Examples + +type Coefficient is digits 10 range -1.0 .. 1.0; +type Real is digits 8; +type Mass is digits 7 range 0.0 .. 1.0E35; +subtype Probability is Real range 0.0 .. 1.0; -- a subtype with a smaller range + +14 + +15 + +16 + +17 + +18 + +19 + +20 + +21 + +22 + +3.5.7 Floating Point Types + +13 December 2012 50 + + Ada Reference Manual — 2012 Edition + +3.5.8 Operations of Floating Point Types + +The following attribute is defined for every floating point subtype S: + +Static Semantics + +S'Digits + +S'Digits denotes the requested decimal precision for the subtype S. The value of this +attribute is of the type universal_integer. The requested decimal precision of the base +subtype of a floating point type T is defined to be the largest value of d for which +ceiling(d * log(10) / log(T'Machine_Radix)) + g <= T'Model_Mantissa +where g is 0 if Machine_Radix is a positive power of 10 and 1 otherwise. + +NOTES +39 The predefined operations of a floating point type include the assignment operation, qualification, the membership +tests, and explicit conversion to and from other numeric types. They also include the relational operators and the following +predefined arithmetic operators: the binary and unary adding operators – and +, certain multiplying operators, the unary +operator abs, and the exponentiation operator. + +40 As for all types, objects of a floating point type have Size and Address attributes (see 13.3). Other attributes of floating +point types are defined in A.5.3. + +3.5.9 Fixed Point Types + +A fixed point type is either an ordinary fixed point type, or a decimal fixed point type. The error bound of +a fixed point type is specified as an absolute value, called the delta of the fixed point type. + +fixed_point_definition ::= ordinary_fixed_point_definition | decimal_fixed_point_definition + +Syntax + +ordinary_fixed_point_definition ::= + delta static_expression real_range_specification + +decimal_fixed_point_definition ::= + delta static_expression digits static_expression [real_range_specification] + +digits_constraint ::= + digits static_expression [range_constraint] + +Name Resolution Rules + +For a type defined by a fixed_point_definition, the delta of the type is specified by the value of the +expression given after the reserved word delta; this expression is expected to be of any real type. For a +type defined by a decimal_fixed_point_definition (a decimal fixed point type), the number of significant +decimal digits for its first subtype (the digits of the first subtype) is specified by the expression given after +the reserved word digits; this expression is expected to be of any integer type. + +Legality Rules + +In a fixed_point_definition or digits_constraint, the expressions given after the reserved words delta and +digits shall be static; their values shall be positive. + +The set of values of a fixed point type comprise the integral multiples of a number called the small of the +type. The machine numbers of a fixed point type are the values of the type that can be represented exactly +in every unconstrained variable of the type. For a type defined by an ordinary_fixed_point_definition (an +ordinary fixed point type), the small may be specified by an attribute_definition_clause (see 13.3); if so +specified, it shall be no greater than the delta of the type. If not specified, the small of an ordinary fixed +point type is an implementation-defined power of two less than or equal to the delta. + +1 + +2/1 + +3 + +4 + +1 + +2 + +3 + +4 + +5 + +6 + +7 + +8/2 + +51 13 December 2012 + +Operations of Floating Point Types 3.5.8 + + + + Ada Reference Manual — 2012 Edition + +9 + +10 + +11 + +12 + +13 + +14 + +15 + +16 + +17 + +18 + +19 + +For a decimal fixed point type, the small equals the delta; the delta shall be a power of 10. If a +real_range_specification is given, both bounds of the range shall be in the range –(10**digits–1)*delta .. ++(10**digits–1)*delta. + +A fixed_point_definition is illegal if the implementation does not support a fixed point type with the given +small and specified range or digits. + +For a subtype_indication with a digits_constraint, the subtype_mark shall denote a decimal fixed point +subtype. + +Static Semantics + +The base range (see 3.5) of a fixed point type is symmetric around zero, except possibly for an extra +negative value in some implementations. + +An ordinary_fixed_point_definition defines an ordinary fixed point type whose base range includes at least +all multiples of small that are between the bounds specified in the real_range_specification. The base +range of the type does not necessarily include the specified bounds themselves. An ordinary_fixed_point_- +definition also defines a constrained first subtype of the type, with each bound of its range given by the +closer to zero of: + +• + +• + +the value of the conversion to the fixed point type of the corresponding expression of the +real_range_specification; + +the corresponding bound of the base range. + +A decimal_fixed_point_definition defines a decimal fixed point type whose base range includes at least +the range –(10**digits–1)*delta .. +(10**digits–1)*delta. A decimal_fixed_point_definition also defines a +constrained first subtype of the type. If a real_range_specification is given, the bounds of the first subtype +are given by a conversion of the values of the expressions of the real_range_specification. Otherwise, the +range of the first subtype is –(10**digits–1)*delta .. +(10**digits–1)*delta. + +The elaboration of a fixed_point_definition creates the fixed point type and its first subtype. + +Dynamic Semantics + +For a digits_constraint on a decimal fixed point subtype with a given delta, if it does not have a +range_constraint, then it specifies an implicit range –(10**D–1)*delta .. +(10**D–1)*delta, where D is +the value of the expression. A digits_constraint is compatible with a decimal fixed point subtype if the +value of the expression is no greater than the digits of the subtype, and if it specifies (explicitly or +implicitly) a range that is compatible with the subtype. + +The elaboration of a digits_constraint consists of the elaboration of the range_constraint, if any. If a +range_constraint is given, a check is made that the bounds of the range are both in the range –(10**D– +1)*delta .. +(10**D–1)*delta, where D is the value of the (static) expression given after the reserved +word digits. If this check fails, Constraint_Error is raised. + +20 + +The implementation shall support at least 24 bits of precision (including the sign bit) for fixed point types. + +Implementation Requirements + +Implementation Permissions + +21 + +Implementations are permitted to support only smalls that are a power of two. In particular, all decimal +fixed point type declarations can be disallowed. Note however that conformance with the Information +Systems Annex requires support for decimal smalls, and decimal fixed point type declarations with digits +up to at least 18. + +3.5.9 Fixed Point Types + +13 December 2012 52 + + Ada Reference Manual — 2012 Edition + +NOTES +41 The base range of an ordinary fixed point type need not include the specified bounds themselves so that the range +specification can be given in a natural way, such as: + + type Fraction is delta 2.0**(-15) range -1.0 .. 1.0; + +With 2's complement hardware, such a type could have a signed 16-bit representation, using 1 bit for the sign and 15 bits +for fraction, resulting in a base range of –1.0 .. 1.0–2.0**(–15). + +Examples of fixed point types and subtypes: + +Examples + +type Volt is delta 0.125 range 0.0 .. 255.0; + -- A pure fraction which requires all the available + -- space in a word can be declared as the type Fraction: +type Fraction is delta System.Fine_Delta range -1.0 .. 1.0; + -- Fraction'Last = 1.0 – System.Fine_Delta +type Money is delta 0.01 digits 15; -- decimal fixed point +subtype Salary is Money digits 10; + -- Money'Last = 10.0**13 – 0.01, Salary'Last = 10.0**8 – 0.01 + +3.5.10 Operations of Fixed Point Types + +The following attributes are defined for every fixed point subtype S: + +Static Semantics + +S'Small + +S'Delta + +S'Fore + +S'Aft + +S'Small denotes the small of the type of S. The value of this attribute is of the type +universal_real. Small may be specified for nonderived ordinary fixed point types via an +attribute_definition_clause (see 13.3); the expression of such a clause shall be static. + +S'Delta denotes the delta of the fixed point subtype S. The value of this attribute is of the +type universal_real. + +S'Fore yields the minimum number of characters needed before the decimal point for the +decimal representation of any value of the subtype S, assuming that the representation does +not include an exponent, but includes a one-character prefix that is either a minus sign or a +space. (This minimum number does not include superfluous zeros or underlines, and is at +least 2.) The value of this attribute is of the type universal_integer. + +S'Aft yields the number of decimal digits needed after the decimal point to accommodate +the delta of the subtype S, unless the delta of the subtype S is greater than 0.1, in which +case the attribute yields the value one. (S'Aft is the smallest positive integer N for which +(10**N)*S'Delta is greater than or equal to one.) The value of this attribute is of the type +universal_integer. + +The following additional attributes are defined for every decimal fixed point subtype S: + +S'Digits + +S'Digits denotes the digits of the decimal fixed point subtype S, which corresponds to the +number of decimal digits that are representable in objects of the subtype. The value of this +attribute is of the type universal_integer. Its value is determined as follows: + +• For a first subtype or a subtype defined by a subtype_indication with a +digits_constraint, the digits is the value of the expression given after the reserved +word digits; + +• For a subtype defined by a subtype_indication without a digits_constraint, the +digits of the subtype is the same as that of the subtype denoted by the +subtype_mark in the subtype_indication. + +53 13 December 2012 + +Fixed Point Types 3.5.9 + +22 + +23 + +24 + +25 + +26 + +27 + +28 + +1 + +2/1 + +3 + +4 + +5 + +6 + +7 + +8 + +9 + + + Ada Reference Manual — 2012 Edition + +10 + +11 + +S'Scale + +• The digits of a base subtype is the largest integer D such that the range –(10**D– + +1)*delta .. +(10**D–1)*delta is included in the base range of the type. + +S'Scale denotes the scale of the subtype S, defined as the value N such that S'Delta = +10.0**(–N). The scale indicates the position of the point relative to the rightmost significant +digits of values of subtype S. The value of this attribute is of the type universal_integer. + +12 + +13 + +14 + +15 + +16 + +17 + +18 + +1 + +2 + +3 + +4 + +5 + +6 + +7/2 + +8 + +S'Round + +S'Round denotes a function with the following specification: + +function S'Round(X : universal_real) + return S'Base + +The function returns the value obtained by rounding X (away from 0, if X is midway +between two values of the type of S). + +NOTES +42 All subtypes of a fixed point type will have the same value for the Delta attribute, in the absence of delta_constraints +(see J.3). + +43 S'Scale is not always the same as S'Aft for a decimal subtype; for example, if S'Delta = 1.0 then S'Aft is 1 while +S'Scale is 0. + +44 The predefined operations of a fixed point type include the assignment operation, qualification, the membership tests, +and explicit conversion to and from other numeric types. They also include the relational operators and the following +predefined arithmetic operators: the binary and unary adding operators – and +, multiplying operators, and the unary +operator abs. + +45 As for all types, objects of a fixed point type have Size and Address attributes (see 13.3). Other attributes of fixed +point types are defined in A.5.4. + +3.6 Array Types + +An array object is a composite object consisting of components which all have the same subtype. The +name for a component of an array uses one or more index values belonging to specified discrete types. The +value of an array object is a composite value consisting of the values of the components. + +array_type_definition ::= + unconstrained_array_definition | constrained_array_definition + +Syntax + +unconstrained_array_definition ::= + array(index_subtype_definition {, index_subtype_definition}) of component_definition + +index_subtype_definition ::= subtype_mark range <> + +constrained_array_definition ::= + array (discrete_subtype_definition {, discrete_subtype_definition}) of component_definition + +discrete_subtype_definition ::= discrete_subtype_indication | range + +component_definition ::= + [aliased] subtype_indication + | [aliased] access_definition + +For a discrete_subtype_definition that is a range, the range shall resolve to be of some specific discrete +type; which discrete type shall be determined without using any context other than the bounds of the range +itself (plus the preference for root_integer — see 8.6). + +Name Resolution Rules + +3.5.10 Operations of Fixed Point Types + +13 December 2012 54 + + + Ada Reference Manual — 2012 Edition + +Legality Rules + +Each index_subtype_definition or discrete_subtype_definition in an array_type_definition defines an +index subtype; its type (the index type) shall be discrete. + +The subtype defined by the subtype_indication of a component_definition (the component subtype) shall +be a definite subtype. + +This paragraph was deleted. + +Static Semantics + +An array is characterized by the number of indices (the dimensionality of the array), the type and position +of each index, the lower and upper bounds for each index, and the subtype of the components. The order +of the indices is significant. + +A one-dimensional array has a distinct component for each possible index value. A multidimensional array +has a distinct component for each possible sequence of index values that can be formed by selecting one +value for each index position (in the given order). The possible values for a given index are all the values +between the lower and upper bounds, inclusive; this range of values is called the index range. The bounds +of an array are the bounds of its index ranges. The length of a dimension of an array is the number of +values of the index range of the dimension (zero for a null range). The length of a one-dimensional array is +the length of its only dimension. + +An array_type_definition defines an array type and its first subtype. For each object of this array type, the +number of indices, the type and position of each index, and the subtype of the components are as in the +type definition; the values of the lower and upper bounds for each index belong to the corresponding index +subtype of its type, except for null arrays (see 3.6.1). + +An unconstrained_array_definition defines an array type with an unconstrained first subtype. Each +index_subtype_definition defines the corresponding index subtype to be the subtype denoted by the +subtype_mark. The compound delimiter <> (called a box) of an index_subtype_definition stands for an +undefined range (different objects of the type need not have the same bounds). + +A constrained_array_definition defines an array type with a constrained first subtype. Each discrete_- +subtype_definition defines the corresponding index subtype, as well as the corresponding index range for +the constrained first subtype. The constraint of the first subtype consists of the bounds of the index ranges. + +The discrete subtype defined by a discrete_subtype_definition is either that defined by the subtype_- +indication, or a subtype determined by the range as follows: + +• If the type of the range resolves to root_integer, then the discrete_subtype_definition defines a +subtype of the predefined type Integer with bounds given by a conversion to Integer of the +bounds of the range; + +• Otherwise, the discrete_subtype_definition defines a subtype of the type of the range, with the + +bounds given by the range. + +The component_definition of an array_type_definition defines the nominal subtype of the components. If +the reserved word aliased appears in the component_definition, then each component of the array is +aliased (see 3.10). + +9 + +10 + +11/2 + +12 + +13 + +14 + +15 + +16 + +17 + +18 + +19 + +20 + +The elaboration of an array_type_definition creates the array type and its first subtype, and consists of the +elaboration of any discrete_subtype_definitions and the component_definition. + +21 + +Dynamic Semantics + +55 13 December 2012 + +Array Types 3.6 + + Ada Reference Manual — 2012 Edition + +22/2 + +The elaboration of a discrete_subtype_definition that does not contain any per-object expressions creates +the discrete subtype, and consists of the elaboration of the subtype_indication or the evaluation of the +range. The elaboration of a discrete_subtype_definition that contains one or more per-object expressions +is defined in 3.8. The elaboration of a component_definition in an array_type_definition consists of the +elaboration of the subtype_indication or access_definition. The elaboration of any discrete_subtype_- +definitions and the elaboration of the component_definition are performed in an arbitrary order. + +22.1/3 + +For an array type with a scalar component type, the following language-defined representation aspect may +be specified with an aspect_specification (see 13.1.1): + +Static Semantics + +22.2/3 + +Default_Component_Value + +This aspect shall be specified by a static expression, and that expression shall be explicit, +even if the aspect has a boolean type. Default_Component_Value shall be specified only on +a full_type_declaration. + +22.3/3 + +If a derived type with no primitive subprograms inherits a boolean Default_Component_Value aspect, the +aspect may be specified to have any value for the derived type. + +22.4/3 + +The expected type for the expression specified for the Default_Component_Value aspect is the +component type of the array type defined by the full_type_declaration on which it appears. + +Name Resolution Rules + +23 + +24 + +25 + +26 + +27 + +28 + +NOTES +46 All components of an array have the same subtype. In particular, for an array of components that are one-dimensional +arrays, this means that all components have the same bounds and hence the same length. + +47 Each elaboration of an array_type_definition creates a distinct array type. A consequence of this is that each object +whose object_declaration contains an array_type_definition is of its own unique type. + +Examples of type declarations with unconstrained array definitions: + +Examples + +type Vector is array(Integer range <>) of Real; +type Matrix is array(Integer range <>, Integer range <>) of Real; +type Bit_Vector is array(Integer range <>) of Boolean; +type Roman is array(Positive range <>) of Roman_Digit; -- see 3.5.2 + +Examples of type declarations with constrained array definitions: +type Table is array(1 .. 10) of Integer; +type Schedule is array(Day) of Boolean; +type Line is array(1 .. Max_Line_Size) of Character; + +29 + +Examples of object declarations with array type definitions: + +30/2 + +Grid : array(1 .. 80, 1 .. 100) of Boolean; +Mix : array(Color range Red .. Green) of Boolean; +Msg_Table : constant array(Error_Code) of access constant String := + (Too_Big => new String'("Result too big"), Too_Small => ...); +Page : array(Positive range <>) of Line := -- an array of arrays + (1 | 50 => Line'(1 | Line'Last => '+', others => '-'), -- see 4.3.3 + 2 .. 49 => Line'(1 | Line'Last => '|', others => ' ')); + -- Page is constrained by its initial value to (1..50) + +3.6 Array Types + +13 December 2012 56 + + + Ada Reference Manual — 2012 Edition + +3.6.1 Index Constraints and Discrete Ranges + +An index_constraint determines the range of possible values for every index of an array subtype, and +thereby the corresponding array bounds. + +index_constraint ::= (discrete_range {, discrete_range}) + +discrete_range ::= discrete_subtype_indication | range + +Syntax + +Name Resolution Rules + +The type of a discrete_range is the type of the subtype defined by the subtype_indication, or the type of +the range. For an index_constraint, each discrete_range shall resolve to be of the type of the +corresponding index. + +Legality Rules + +An index_constraint shall appear only in a subtype_indication whose subtype_mark denotes either an +unconstrained array subtype, or an unconstrained access subtype whose designated subtype is an +unconstrained array subtype; in either case, the index_constraint shall provide a discrete_range for each +index of the array type. + +A discrete_range defines a range whose bounds are given by the range, or by the range of the subtype +defined by the subtype_indication. + +Static Semantics + +Dynamic Semantics + +An index_constraint is compatible with an unconstrained array subtype if and only if the index range +defined by each discrete_range is compatible (see 3.5) with the corresponding index subtype. If any of +the discrete_ranges defines a null range, any array thus constrained is a null array, having no +components. An array value satisfies an index_constraint if at each index position the array value and the +index_constraint have the same index bounds. + +The elaboration of an index_constraint consists of the evaluation of the discrete_range(s), in an arbitrary +order. The evaluation of a discrete_range consists of the elaboration of the subtype_indication or the +evaluation of the range. + +NOTES +48 The elaboration of a subtype_indication consisting of a subtype_mark followed by an index_constraint checks the +compatibility of the index_constraint with the subtype_mark (see 3.2.2). + +49 Even if an array value does not satisfy the index constraint of an array subtype, Constraint_Error is not raised on +conversion to the array subtype, so long as the length of each dimension of the array value and the array subtype match. +See 4.6. + +Examples + +Examples of array declarations including an index constraint: + +Board : Matrix(1 .. 8, 1 .. 8); -- see 3.6 +Rectangle : Matrix(1 .. 20, 1 .. 30); +Inverse : Matrix(1 .. N, 1 .. N); -- N need not be static +Filter : Bit_Vector(0 .. 31); + +1 + +2 + +3 + +4 + +5 + +6 + +7 + +8 + +9 + +10 + +11 + +12 + +13 + +57 13 December 2012 + +Index Constraints and Discrete Ranges 3.6.1 + + Ada Reference Manual — 2012 Edition + +Example of array declaration with a constrained array subtype: + +My_Schedule : Schedule; -- all arrays of type Schedule have the same bounds + +Example of record type with a component that is an array: + +type Var_Line(Length : Natural) is + record + Image : String(1 .. Length); + end record; +Null_Line : Var_Line(0); -- Null_Line.Image is a null array + +3.6.2 Operations of Array Types + +Legality Rules + +The argument N used in the attribute_designators for the N-th dimension of an array shall be a static +expression of some integer type. The value of N shall be positive (nonzero) and no greater than the +dimensionality of the array. + +14 +15 + +16 + +17 + +18 + +1 + +Static Semantics + +2/1 + +The following attributes are defined for a prefix A that is of an array type (after any implicit dereference), +or denotes a constrained array subtype: + +3 + +4 + +5 + +6 + +7 + +8 + +9 + +A'First + +A'First denotes the lower bound of the first index range; its type is the corresponding index +type. + +A'First(N) + +A'First(N) denotes the lower bound of the N-th index range; its type is the corresponding +index type. + +A'Last + +A'Last(N) + +A'Range + +A'Last denotes the upper bound of the first index range; its type is the corresponding index +type. + +A'Last(N) denotes the upper bound of the N-th index range; its type is the corresponding +index type. + +A'Range is equivalent to the range A'First .. A'Last, except that the prefix A is only +evaluated once. + +A'Range(N) A'Range(N) is equivalent to the range A'First(N) .. A'Last(N), except that the prefix A is + +only evaluated once. + +A'Length + +A'Length denotes the number of values of the first index range (zero for a null range); its +type is universal_integer. + +10 + +A'Length(N) A'Length(N) denotes the number of values of the N-th index range (zero for a null range); + +its type is universal_integer. + +Implementation Advice + +11/3 + +12 + +13 + +An implementation should normally represent multidimensional arrays in row-major order, consistent with +the notation used for multidimensional array aggregates (see 4.3.3). However, if convention Fortran is +specified for a multidimensional array type, then column-major order should be used instead (see B.5, +“Interfacing with Fortran”). + +NOTES +50 The attribute_references A'First and A'First(1) denote the same value. A similar relation exists for the +attribute_references A'Last, A'Range, and A'Length. The following relation is satisfied (except for a null array) by the +above attributes if the index type is an integer type: + + A'Length(N) = A'Last(N) - A'First(N) + 1 + +3.6.1 Index Constraints and Discrete Ranges + +13 December 2012 58 + + Ada Reference Manual — 2012 Edition + +51 An array type is limited if its component type is limited (see 7.5). + +52 The predefined operations of an array type include the membership tests, qualification, and explicit conversion. If the +array type is not limited, they also include assignment and the predefined equality operators. For a one-dimensional array +type, they include the predefined concatenation operators (if nonlimited) and, if the component type is discrete, the +predefined relational operators; if the component type is boolean, the predefined logical operators are also included. + +14 + +15 + +53 A component of an array can be named with an indexed_component. A value of an array type can be specified with an +array_aggregate. For a one-dimensional array type, a slice of the array can be named; also, string literals are defined if the +component type is a character type. + +16/2 + +Examples (using arrays declared in the examples of subclause 3.6.1): + +Examples + +-- Filter'First = 0 Filter'Last = 31 Filter'Length = 32 +-- Rectangle'Last(1) = 20 Rectangle'Last(2) = 30 + +3.6.3 String Types + +Static Semantics + +A one-dimensional array type whose component type is a character type is called a string type. + +There are three predefined string types, String, Wide_String, and Wide_Wide_String, each indexed by +values of the predefined subtype Positive; these are declared in the visible part of package Standard: + +subtype Positive is Integer range 1 .. Integer'Last; +type String is array(Positive range <>) of Character; +type Wide_String is array(Positive range <>) of Wide_Character; +type Wide_Wide_String is array(Positive range <>) of Wide_Wide_Character; + +NOTES +54 String literals (see 2.6 and 4.2) are defined for all string types. The concatenation operator & is predefined for string +types, as for all nonlimited one-dimensional array types. The ordering operators <, <=, >, and >= are predefined for string +types, as for all one-dimensional discrete array types; these ordering operators correspond to lexicographic order (see +4.5.2). + +Examples of string objects: + +Stars : String(1 .. 120) := (1 .. 120 => '*' ); +Question : constant String := "How many characters?"; + +Examples + +characters) +Ask_Twice : String := Question & Question; +Ninety_Six : constant Roman := "XCVI"; -- see 3.5.2 and 3.6 + +-- constrained to (1..40) + +-- Question'First = 1, Question'Last = 20 +-- Question'Length = 20 (the number of + +17 + +18 + +1 + +2/2 + +3 + +4/2 + +5 + +6 + +7 + +8 + +59 13 December 2012 + +Operations of Array Types 3.6.2 + + + + + Ada Reference Manual — 2012 Edition + +3.7 Discriminants + +1/2 + +2/2 + +3 + +4 + +5/2 + +6 + +7 + +8/2 + +9/2 + +9.1/3 + +10/3 + +A composite type (other than an array or interface type) can have discriminants, which parameterize the +type. A known_discriminant_part specifies the discriminants of a composite type. A discriminant of an +object is a component of the object, and is either of a discrete type or an access type. An +unknown_discriminant_part in the declaration of a view of a type specifies that the discriminants of the +type are unknown for the given view; all subtypes of such a view are indefinite subtypes. + +discriminant_part ::= unknown_discriminant_part | known_discriminant_part + +Syntax + +unknown_discriminant_part ::= (<>) + +known_discriminant_part ::= + (discriminant_specification {; discriminant_specification}) + +discriminant_specification ::= + defining_identifier_list : [null_exclusion] subtype_mark [:= default_expression] + | defining_identifier_list : access_definition [:= default_expression] + +default_expression ::= expression + +The expected type for the default_expression of a discriminant_specification is that of the corresponding +discriminant. + +Name Resolution Rules + +Legality Rules + +A discriminant_part is only permitted in a declaration for a composite type that is not an array or interface +type (this includes generic formal types). A type declared with a known_discriminant_part is called a +discriminated type, as is a type that inherits (known) discriminants. + +The subtype of a discriminant may be defined by an optional null_exclusion and a subtype_mark, in +which case the subtype_mark shall denote a discrete or access subtype, or it may be defined by an +access_definition. A discriminant that is defined by an access_definition is called an access discriminant +and is of an anonymous access type. + +Default_expressions shall be provided either for all or for none of the discriminants of a known_- +discriminant_part. No default_expressions are permitted in a known_discriminant_part in a declaration +of a nonlimited tagged type or a generic formal type. + +A discriminant_specification for an access discriminant may have a default_expression only in the +declaration for an immutably limited type (see 7.5). In addition to the places where Legality Rules +normally apply (see 12.3), this rule applies also in the private part of an instance of a generic unit. + +11/2 + +This paragraph was deleted. + +12 + +13 + +14 + +For a type defined by a derived_type_definition, if a known_discriminant_part is provided in its +declaration, then: + +• The parent subtype shall be constrained; +• If the parent type is not a tagged type, then each discriminant of the derived type shall be used in + +the constraint defining the parent subtype; + +3.7 Discriminants + +13 December 2012 60 + + Ada Reference Manual — 2012 Edition + +• If a discriminant is used in the constraint defining the parent subtype, the subtype of the +discriminant shall be statically compatible (see 4.9.1) with the subtype of the corresponding +parent discriminant. + +This paragraph was deleted. + +Static Semantics + +A discriminant_specification declares a discriminant; the subtype_mark denotes its subtype unless it is an +access discriminant, in which case the discriminant's subtype is the anonymous access-to-variable subtype +defined by the access_definition. + +For a type defined by a derived_type_definition, each discriminant of the parent type is either inherited, +constrained to equal some new discriminant of the derived type, or constrained to the value of an +expression. When inherited or constrained to equal some new discriminant, the parent discriminant and the +discriminant of the derived type are said to correspond. Two discriminants also correspond if there is some +common discriminant to which they both correspond. A discriminant corresponds to itself as well. If a +discriminant of a parent type is constrained to a specific value by a derived_type_definition, then that +discriminant is said to be specified by that derived_type_definition. + +A constraint that appears within the definition of a discriminated type depends on a discriminant of the +type if it names the discriminant as a bound or discriminant value. A component_definition depends on a +discriminant if its constraint depends on the discriminant, or on a discriminant that corresponds to it. + +A component depends on a discriminant if: + +• Its component_definition depends on the discriminant; or +• It is declared in a variant_part that is governed by the discriminant; or +• It is a component inherited as part of a derived_type_definition, and the constraint of the + +parent_subtype_indication depends on the discriminant; or + +• It is a subcomponent of a component that depends on the discriminant. + +Each value of a discriminated type includes a value for each component of the type that does not depend +on a discriminant; this includes the discriminants themselves. The values of discriminants determine which +other component values are present in the value of the discriminated type. + +A type declared with a known_discriminant_part is said to have known discriminants; its first subtype is +unconstrained. A type declared with an unknown_discriminant_part is said to have unknown +discriminants. A type declared without a discriminant_part has no discriminants, unless it is a derived +type; if derived, such a type has the same sort of discriminants (known, unknown, or none) as its parent (or +ancestor) type. A tagged class-wide type also has unknown discriminants. Any subtype of a type with +unknown discriminants is an unconstrained and indefinite subtype (see 3.2 and 3.3). + +Dynamic Semantics + +For an access discriminant, its access_definition is elaborated when the value of the access discriminant is +defined: by evaluation of its default_expression, by elaboration of a discriminant_constraint, or by an +assignment that initializes the enclosing object. + +NOTES +55 If a discriminated type has default_expressions for its discriminants, then unconstrained variables of the type are +permitted, and the values of the discriminants can be changed by an assignment to such a variable. If defaults are not +provided for the discriminants, then all variables of the type are constrained, either by explicit constraint or by their initial +value; the values of the discriminants of such a variable cannot be changed after initialization. + +15 + +16/3 + +17 + +18 + +19 + +20 + +21 + +22 + +23 + +24 + +25 + +26 + +27/2 + +28 + +61 13 December 2012 + +Discriminants 3.7 + + 29 + +30 + +31 + +32 + +33 + +34 + +35 + +36 + +37/3 + +1 + +2 + +3 + +4 + +5 + +Ada Reference Manual — 2012 Edition + +56 The default_expression for a discriminant of a type is evaluated when an object of an unconstrained subtype of the +type is created. + +57 Assignment to a discriminant of an object (after its initialization) is not allowed, since the name of a discriminant is a +constant; neither assignment_statements nor assignments inherent in passing as an in out or out parameter are allowed. +Note however that the value of a discriminant can be changed by assigning to the enclosing object, presuming it is an +unconstrained variable. + +58 A discriminant that is of a named access type is not called an access discriminant; that term is used only for +discriminants defined by an access_definition. + +Examples of discriminated types: + +Examples + +type Buffer(Size : Buffer_Size := 100) is -- see 3.5.4 + record + Pos : Buffer_Size := 0; + Value : String(1 .. Size); + end record; +type Matrix_Rec(Rows, Columns : Integer) is + record + Mat : Matrix(1 .. Rows, 1 .. Columns); -- see 3.6 + end record; +type Square(Side : Integer) is new + Matrix_Rec(Rows => Side, Columns => Side); +type Double_Square(Number : Integer) is + record + Left : Square(Number); + Right : Square(Number); + end record; +task type Worker(Prio : System.Priority; Buf : access Buffer) + with Priority => Prio is -- see D.1 + -- discriminants used to parameterize the task type (see 9.1) + entry Fill; + entry Drain; +end Worker; + +3.7.1 Discriminant Constraints + +A discriminant_constraint specifies the values of the discriminants for a given discriminated type. + +discriminant_constraint ::= + (discriminant_association {, discriminant_association}) + +Syntax + +discriminant_association ::= + [discriminant_selector_name {| discriminant_selector_name} =>] expression + +A discriminant_association is said to be named if it has one or more discriminant_selector_names; +it is otherwise said to be positional. In a discriminant_constraint, any positional associations shall +precede any named associations. + +Name Resolution Rules + +Each selector_name of a named discriminant_association shall resolve to denote a discriminant of the +subtype being constrained; the discriminants so named are the associated discriminants of the named +association. For a positional association, the associated discriminant is the one whose discriminant_- +specification occurred in the corresponding position in the known_discriminant_part that defined the +discriminants of the subtype being constrained. + +3.7 Discriminants + +13 December 2012 62 + + Ada Reference Manual — 2012 Edition + +The expected type for the expression in a discriminant_association is that of the associated +discriminant(s). + +6 + +Legality Rules + +A discriminant_constraint is only allowed in a subtype_indication whose subtype_mark denotes either an +unconstrained discriminated subtype, or an unconstrained access subtype whose designated subtype is an +unconstrained discriminated subtype. However, in the case of an access subtype, a discriminant_constraint +is legal only if any dereference of a value of the access type is known to be constrained (see 3.3). In +addition to the places where Legality Rules normally apply (see 12.3), these rules apply also in the private +part of an instance of a generic unit. + +A named discriminant_association with more than one selector_name is allowed only if the named +discriminants are all of the same type. A discriminant_constraint shall provide exactly one value for each +discriminant of the subtype being constrained. + +This paragraph was deleted. + +Dynamic Semantics + +A discriminant_constraint is compatible with an unconstrained discriminated subtype if each discriminant +value belongs to the subtype of the corresponding discriminant. + +A composite value satisfies a discriminant constraint if and only if each discriminant of the composite +value has the value imposed by the discriminant constraint. + +For the elaboration of a discriminant_constraint, the expressions in the discriminant_associations are +evaluated in an arbitrary order and converted to the type of the associated discriminant (which might raise +Constraint_Error — see 4.6); the expression of a named association is evaluated (and converted) once for +each associated discriminant. The result of each evaluation and conversion is the value imposed by the +constraint for the associated discriminant. + +7/3 + +8 + +9/3 + +10 + +11 + +12 + +NOTES +59 The rules of the language ensure that a discriminant of an object always has a value, either from explicit or implicit +initialization. + +13 + +Examples (using types declared above in subclause 3.7): + +Examples + +Large : Buffer(200); -- constrained, always 200 characters + -- (explicit discriminant value) +Message : Buffer; -- unconstrained, initially 100 characters + -- (default discriminant value) +Basis : Square(5); -- constrained, always 5 by 5 +Illegal : Square; -- illegal, a Square has to be constrained + +14/3 + +15 + +3.7.2 Operations of Discriminated Types + +If a discriminated type has default_expressions for its discriminants, then unconstrained variables of the +type are permitted, and the discriminants of such a variable can be changed by assignment to the variable. +For a formal parameter of such a type, an attribute is provided to determine whether the corresponding +actual parameter is constrained or unconstrained. + +1 + +63 13 December 2012 + +Discriminant Constraints 3.7.1 + + Ada Reference Manual — 2012 Edition + +2 + +For a prefix A that is of a discriminated type (after any implicit dereference), the following attribute is +defined: + +Static Semantics + +3/3 + +A'Constrained + +Yields the value True if A denotes a constant, a value, a tagged object, or a constrained +variable, and False otherwise. + +4 + +1 + +2 + +3 + +4 + +5/1 + +6/3 + +Erroneous Execution + +The execution of a construct is erroneous if the construct has a constituent that is a name denoting a +subcomponent that depends on discriminants, and the value of any of these discriminants is changed by +this execution between evaluating the name and the last use (within this execution) of the subcomponent +denoted by the name. + +3.8 Record Types + +A record object is a composite object consisting of named components. The value of a record object is a +composite value consisting of the values of the components. + +record_type_definition ::= [[abstract] tagged] [limited] record_definition + +Syntax + +record_definition ::= + record + component_list + end record + | null record + +component_list ::= + component_item {component_item} + | {component_item} variant_part + | null; + +component_item ::= component_declaration | aspect_clause + +component_declaration ::= + defining_identifier_list : component_definition [:= default_expression] + [aspect_specification]; + +Name Resolution Rules + +7 + +The expected type for the default_expression, if any, in a component_declaration is the type of the +component. + +8/2 + +9/2 + +This paragraph was deleted. + +Legality Rules + +Each component_declaration declares a component of the record type. Besides components declared by +component_declarations, the components of a record type include any components declared by +discriminant_specifications of the record type declaration. The identifiers of all components of a record +type shall be distinct. + +10 + +Within a type_declaration, a name that denotes a component, protected subprogram, or entry of the type +is allowed only in the following cases: + +3.7.2 Operations of Discriminated Types + +13 December 2012 64 + + + Ada Reference Manual — 2012 Edition + +• A name that denotes any component, protected subprogram, or entry is allowed within an +aspect_specification, an operational item, or a representation item that occurs within the +declaration of the composite type. + +• A name that denotes a noninherited discriminant is allowed within the declaration of the type, +but not within the discriminant_part. If the discriminant is used to define the constraint of a +component, the bounds of an entry family, or the constraint of the parent subtype in a +derived_type_definition, then its name shall appear alone as a direct_name (not as part of a +larger expression or expanded name). A discriminant shall not be used to define the constraint of +a scalar component. + +11/3 + +12/3 + +If the name of the current instance of a type (see 8.6) is used to define the constraint of a component, then +it shall appear as a direct_name that is the prefix of an attribute_reference whose result is of an access +type, and the attribute_reference shall appear alone. + +13 + +If a record_type_definition includes the reserved word limited, the type is called an explicitly limited +record type. + +13.1/3 + +Static Semantics + +The component_definition of a component_declaration defines the (nominal) subtype of the component. +If the reserved word aliased appears in the component_definition, then the component is aliased (see +3.10). + +If the component_list of a record type is defined by the reserved word null and there are no discriminants, +then the record type has no components and all records of the type are null records. A record_definition of +null record is equivalent to record null; end record. + +Dynamic Semantics + +The elaboration of a record_type_definition creates the record type and its first subtype, and consists of +the elaboration of the record_definition. The elaboration of a record_definition consists of the elaboration +of its component_list, if any. + +The elaboration of a component_list consists of the elaboration of the component_items and variant_part, +if any, in the order in which they appear. The elaboration of a component_declaration consists of the +elaboration of the component_definition. + +Within the definition of a composite type, if a component_definition or discrete_subtype_definition (see +9.5.2) includes a name that denotes a discriminant of the type, or that is an attribute_reference whose +prefix denotes the current instance of the type, the expression containing the name is called a per-object +expression, and the constraint or range being defined is called a per-object constraint. For the elaboration +of a component_definition of a component_declaration or the discrete_subtype_definition of an entry_- +declaration for an entry family (see 9.5.2), if the component subtype is defined by an access_definition or +if the constraint or range of the subtype_indication or discrete_subtype_definition is not a per-object +constraint, then the access_definition, subtype_indication, or discrete_subtype_definition is elaborated. +On the other hand, if the constraint or range is a per-object constraint, then the elaboration consists of the +evaluation of any included expression that is not part of a per-object expression. Each such expression is +evaluated once unless it is part of a named association in a discriminant constraint, in which case it is +evaluated once for each associated discriminant. + +14 + +15 + +16 + +17 + +18/2 + +When a per-object constraint is elaborated (as part of creating an object), each per-object expression of the +constraint is evaluated. For other expressions, the values determined during the elaboration of the +component_definition or entry_declaration are used. Any checks associated with the enclosing + +18.1/1 + +65 13 December 2012 + +Record Types 3.8 + + Ada Reference Manual — 2012 Edition + +subtype_indication or discrete_subtype_definition are performed, including the subtype compatibility +check (see 3.2.2), and the associated subtype is created. + +19 + +20 + +21 + +22 + +23 + +24 + +NOTES +60 A component_declaration with several identifiers is equivalent to a sequence of single component_declarations, as +explained in 3.3.1. + +61 The default_expression of a record component is only evaluated upon the creation of a default-initialized object of the +record type (presuming the object has the component, if it is in a variant_part — see 3.3.1). + +62 The subtype defined by a component_definition (see 3.6) has to be a definite subtype. + +63 If a record type does not have a variant_part, then the same components are present in all values of the type. + +64 A record type is limited if it has the reserved word limited in its definition, or if any of its components are limited (see +7.5). + +65 The predefined operations of a record type include membership tests, qualification, and explicit conversion. If the +record type is nonlimited, they also include assignment and the predefined equality operators. + +25/2 + +66 A component of a record can be named with a selected_component. A value of a record can be specified with a +record_aggregate. + +26 + +27 + +28 + +29 + +30 + +31 + +1 + +2 + +3 + +4 + +Examples of record type declarations: + +Examples + +type Date is + record + Day : Integer range 1 .. 31; + Month : Month_Name; + Year : Integer range 0 .. 4000; + end record; +type Complex is + record + Re : Real := 0.0; + Im : Real := 0.0; + end record; + +Examples of record variables: + +Tomorrow, Yesterday : Date; +A, B, C : Complex; +-- both components of A, B, and C are implicitly initialized to zero + +3.8.1 Variant Parts and Discrete Choices + +A record type with a variant_part specifies alternative lists of components. Each variant defines the +components for the value or values of the discriminant covered by its discrete_choice_list. + +Syntax + +variant_part ::= + case discriminant_direct_name is + variant + {variant} + end case; + +variant ::= + when discrete_choice_list => + component_list + +discrete_choice_list ::= discrete_choice {| discrete_choice} + +3.8 Record Types + +13 December 2012 66 + + Ada Reference Manual — 2012 Edition + +discrete_choice ::= choice_expression | discrete_subtype_indication | range | others + +Name Resolution Rules + +The discriminant_direct_name shall resolve to denote a discriminant (called the discriminant of the +variant_part) specified in the known_discriminant_part of the full_type_declaration that contains the +variant_part. The expected type for each discrete_choice in a variant is the type of the discriminant of the +variant_part. + +The discriminant of the variant_part shall be of a discrete type. + +Legality Rules + +The choice_expressions, subtype_indications, and ranges given as discrete_choices in a variant_part +shall be static. The discrete_choice others shall appear alone in a discrete_choice_list, and such a +discrete_choice_list, if it appears, shall be the last one in the enclosing construct. + +A discrete_choice is defined to cover a value in the following cases: + +• A discrete_choice that is a choice_expression covers a value if the value equals the value of + +the choice_expression converted to the expected type. + +5/3 + +6 + +7 + +8/3 + +9 + +10/3 + +• A discrete_choice that is a subtype_indication covers all values (possibly none) that belong to + +10.1/3 + +the subtype and that satisfy the static predicate of the subtype (see 3.2.4). + +• A discrete_choice that is a range covers all values (possibly none) that belong to the range. +• The discrete_choice others covers all values of its expected type that are not covered by + +previous discrete_choice_lists of the same construct. + +A discrete_choice_list covers a value if one of its discrete_choices covers the value. + +The possible values of the discriminant of a variant_part shall be covered as follows: + +• If the discriminant is of a static constrained scalar subtype then, except within an instance of a +generic unit, each non-others discrete_choice shall cover only values in that subtype that satisfy +its predicate, and each value of that subtype that satisfies its predicate shall be covered by some +discrete_choice (either explicitly or by others); + +11/3 + +12 + +13 + +14 + +15/3 + +• If the type of the discriminant is a descendant of a generic formal scalar type, then the + +16/3 + +variant_part shall have an others discrete_choice; + +• Otherwise, each value of the base range of the type of the discriminant shall be covered (either + +explicitly or by others). + +Two distinct discrete_choices of a variant_part shall not cover the same value. + +If the component_list of a variant is specified by null, the variant has no components. + +Static Semantics + +The discriminant of a variant_part is said to govern the variant_part and its variants. In addition, the +discriminant of a derived type governs a variant_part and its variants if it corresponds (see 3.7) to the +discriminant of the variant_part. + +A record value contains the values of the components of a particular variant only if the value of the +discriminant governing the variant is covered by the discrete_choice_list of the variant. This rule applies +in turn to any further variant that is, itself, included in the component_list of the given variant. + +Dynamic Semantics + +17 + +18 + +19 + +20 + +21 + +67 13 December 2012 + +Variant Parts and Discrete Choices 3.8.1 + + Ada Reference Manual — 2012 Edition + +21.1/3 + +When an object of a discriminated type T is initialized by default, Constraint_Error is raised if no +discrete_choice_list of any variant of a variant_part of T covers the value of the discriminant that governs +the variant_part. When a variant_part appears in the component_list of another variant V, this test is only +applied if the value of the discriminant governing V is covered by the discrete_choice_list of V. + +22 + +23 + +24 + +25 + +26 + +27 + +28 + +29 + +The elaboration of a variant_part consists of the elaboration of the component_list of each variant in the +order in which they appear. + +Example of record type with a variant part: + +Examples + +type Device is (Printer, Disk, Drum); +type State is (Open, Closed); +type Peripheral(Unit : Device := Disk) is + record + Status : State; + case Unit is + when Printer => + Line_Count : Integer range 1 .. Page_Size; + when others => + Cylinder : Cylinder_Index; + Track : Track_Number; + end case; + end record; + +Examples of record subtypes: + +subtype Drum_Unit is Peripheral(Drum); +subtype Disk_Unit is Peripheral(Disk); + +Examples of constrained record variables: + +Writer : Peripheral(Unit => Printer); +Archive : Disk_Unit; + +3.9 Tagged Types and Type Extensions + +1 + +Tagged types and type extensions support object-oriented programming, based on inheritance with +extension and run-time polymorphism via dispatching operations. + +Static Semantics + +2/2 + +2.1/2 + +A record type or private type that has the reserved word tagged in its declaration is called a tagged type. +In addition, an interface type is a tagged type, as is a task or protected type derived from an interface (see +3.9.4). When deriving from a tagged type, as for any derived type, additional primitive subprograms may +be defined, and inherited primitive subprograms may be overridden. The derived type is called an +extension of its ancestor types, or simply a type extension. + +Every type extension is also a tagged type, and is a record extension or a private extension of some other +tagged type, or a noninterface synchronized tagged type (see 3.9.4). A record extension is defined by a +derived_type_definition with a record_extension_part (see 3.9.1), which may include the definition of +additional components. A private extension, which is a partial view of a record extension or of a +synchronized tagged type, can be declared in the visible part of a package (see 7.3) or in a generic formal +part (see 12.5.1). + +3 + +An object of a tagged type has an associated (run-time) tag that identifies the specific tagged type used to +create the object originally. The tag of an operand of a class-wide tagged type T'Class controls which + +3.8.1 Variant Parts and Discrete Choices + +13 December 2012 68 + + Ada Reference Manual — 2012 Edition + +subprogram body is to be executed when a primitive subprogram of type T is applied to the operand (see +3.9.2); using a tag to control which body to execute is called dispatching. + +The tag of a specific tagged type identifies the full_type_declaration of the type, and for a type extension, +is sufficient to uniquely identify the type among all descendants of the same ancestor. If a declaration for a +tagged type occurs within a generic_package_declaration, then the corresponding type declarations in +distinct instances of the generic package are associated with distinct tags. For a tagged type that is local to +a generic package body and with all of its ancestors (if any) also local to the generic body, the language +does not specify whether repeated instantiations of the generic body result in distinct tags. + +The following language-defined library package exists: + +package Ada.Tags is + pragma Preelaborate(Tags); + type Tag is private; + pragma Preelaborable_Initialization(Tag); + No_Tag : constant Tag; + function Expanded_Name(T : Tag) return String; + function Wide_Expanded_Name(T : Tag) return Wide_String; + function Wide_Wide_Expanded_Name(T : Tag) return Wide_Wide_String; + function External_Tag(T : Tag) return String; + function Internal_Tag(External : String) return Tag; + function Descendant_Tag(External : String; Ancestor : Tag) return Tag; + function Is_Descendant_At_Same_Level(Descendant, Ancestor : Tag) + return Boolean; + function Parent_Tag (T : Tag) return Tag; + type Tag_Array is array (Positive range <>) of Tag; + function Interface_Ancestor_Tags (T : Tag) return Tag_Array; + function Is_Abstract (T : Tag) return Boolean; + Tag_Error : exception; +private + ... -- not specified by the language +end Ada.Tags; + +No_Tag is the default initial value of type Tag. + +The function Wide_Wide_Expanded_Name returns the full expanded name of the first subtype of the +specific type identified by the tag, in upper case, starting with a root library unit. The result is +implementation defined if the type is declared within an unnamed block_statement. + +The function Expanded_Name (respectively, Wide_Expanded_Name) returns the same sequence of +graphic characters as that defined for Wide_Wide_Expanded_Name, if all the graphic characters are +defined +is +implementation defined, but no shorter than that returned by Wide_Wide_Expanded_Name for the same +value of the argument. + +in Character (respectively, Wide_Character); otherwise, + +the sequence of characters + +4/2 + +5 + +6/2 + +6.1/2 + +7/2 + +7.1/2 + +7.2/2 + +7.3/2 + +7.4/2 + +7.5/3 + +8 + +9 + +9.1/2 + +10/2 + +10.1/2 + +The function External_Tag returns a string to be used in an external representation for the given tag. The +call External_Tag(S'Tag) is equivalent to the attribute_reference S'External_Tag (see 13.3). + +11 + +The string returned by the functions Expanded_Name, Wide_Expanded_Name, Wide_Wide_Expanded_- +Name, and External_Tag has lower bound 1. + +11.1/2 + +The function Internal_Tag returns a tag that corresponds to the given external tag, or raises Tag_Error if +the given string is not the external tag for any specific type of the partition. Tag_Error is also raised if the +specific type identified is a library-level type whose tag has not yet been created (see 13.14). + +12/2 + +69 13 December 2012 + +Tagged Types and Type Extensions 3.9 + + 12.1/3 + +12.2/2 + +12.3/3 + +Ada Reference Manual — 2012 Edition + +The function Descendant_Tag returns the (internal) tag for the type that corresponds to the given external +tag and is both a descendant of the type identified by the Ancestor tag and has the same accessibility level +as the identified ancestor. Tag_Error is raised if External is not the external tag for such a type. Tag_Error +is also raised if the specific type identified is a library-level type whose tag has not yet been created, or if +the given external tag identifies more than one type that has the appropriate Ancestor and accessibility +level. + +The function Is_Descendant_At_Same_Level returns True if the Descendant tag identifies a type that is +both a descendant of the type identified by Ancestor and at the same accessibility level. If not, it returns +False. + +of + +the + +purposes + +For +and +Is_Descendant_At_Same_Level, a tagged type T2 is a descendant of a type T1 if it is the same as T1, or if +its parent type or one of its progenitor types is a descendant of type T1 by this rule, even if at the point of +the declaration of T2, one of the derivations in the chain is not visible. + +functions Descendant_Tag + +semantics + +dynamic + +the + +of + +12.4/3 + +The function Parent_Tag returns the tag of the parent type of the type whose tag is T. If the type does not +have a parent type (that is, it was not declared by a derived_type_declaration), then No_Tag is returned. + +12.5/3 + +The function Interface_Ancestor_Tags returns an array containing the tag of each interface ancestor type +of the type whose tag is T, other than T itself. The lower bound of the returned array is 1, and the order of +the returned tags is unspecified. Each tag appears in the result exactly once. If the type whose tag is T has +no interface ancestors, a null array is returned. + +12.6/3 + +The function Is_Abstract returns True if the type whose tag is T is abstract, and False otherwise. + +13 + +14 + +15 + +For every subtype S of a tagged type T (specific or class-wide), the following attributes are defined: + +S'Class + +S'Class denotes a subtype of the class-wide type (called T'Class in this International +Standard) for the class rooted at T (or if S already denotes a class-wide subtype, then +S'Class is the same as S). + +S'Class is unconstrained. However, if S is constrained, then the values of S'Class are only +those that when converted to the type T belong to S. + +16 + +S'Tag + +S'Tag denotes the tag of the type T (or if T is class-wide, the tag of the root type of the +corresponding class). The value of this attribute is of type Tag. + +17 + +Given a prefix X that is of a class-wide tagged type (after any implicit dereference), the following attribute +is defined: + +18 + +X'Tag + +X'Tag denotes the tag of X. The value of this attribute is of type Tag. + +18.1/2 + +The following language-defined generic function exists: + +18.2/3 + +generic + type T (<>) is abstract tagged limited private; + type Parameters (<>) is limited private; + with function Constructor (Params : not null access Parameters) + return T is abstract; +function Ada.Tags.Generic_Dispatching_Constructor + (The_Tag : Tag; + Params : not null access Parameters) return T'Class + with Convention => Intrinsic; +pragma Preelaborate(Generic_Dispatching_Constructor); + +18.3/2 + +Tags.Generic_Dispatching_Constructor provides a mechanism to create an object of an appropriate type +from just a tag value. The function Constructor is expected to create the object given a reference to an +object of type Parameters. + +3.9 Tagged Types and Type Extensions + +13 December 2012 70 + + + Ada Reference Manual — 2012 Edition + +Dynamic Semantics + +The tag associated with an object of a tagged type is determined as follows: + +• The tag of a stand-alone object, a component, or an aggregate of a specific tagged type T + +identifies T. + +• The tag of an object created by an allocator for an access type with a specific designated tagged + +type T, identifies T. + +• The tag of an object of a class-wide tagged type is that of its initialization expression. +• The tag of the result returned by a function whose result type is a specific tagged type T + +identifies T. + +• The tag of the result returned by a function with a class-wide result type is that of the return + +object. + +The tag is preserved by type conversion and by parameter passing. The tag of a value is the tag of the +associated object (see 6.2). + +Tag_Error is raised by a call of Descendant_Tag, Expanded_Name, External_Tag, Interface_Ancestor_- +or +Tags, +Wide_Wide_Expanded_Name if any tag passed is No_Tag. + +Parent_Tag, Wide_Expanded_Name, + +Is_Descendant_At_Same_Level, + +Is_Abstract, + +An instance of Tags.Generic_Dispatching_Constructor raises Tag_Error if The_Tag does not represent a +concrete descendant of T or if the innermost master (see 7.6.1) of this descendant is not also a master of +the instance. Otherwise, it dispatches to the primitive function denoted by the formal Constructor for the +type identified by The_Tag, passing Params, and returns the result. Any exception raised by the function is +propagated. + +19 + +20 + +21 + +22 + +23 + +24/2 + +25 + +25.1/3 + +25.2/2 + +Erroneous Execution + +If an internal tag provided to an instance of Tags.Generic_Dispatching_Constructor or to any subprogram +declared in package Tags identifies either a type that is not library-level and whose tag has not been +created (see 13.14), or a type that does not exist in the partition at the time of the call, then execution is +erroneous. + +25.3/2 + +The implementation of Internal_Tag and Descendant_Tag may raise Tag_Error if no specific type +corresponding to the string External passed as a parameter exists in the partition at the time the function is +called, or if there is no such type whose innermost master is a master of the point of the function call. + +26/2 + +Implementation Permissions + +Internal_Tag should return the tag of a type, if one exists, whose innermost master is a master of the point +of the function call. + +26.1/3 + +Implementation Advice + +NOTES +67 A type declared with the reserved word tagged should normally be declared in a package_specification, so that new +primitive subprograms can be declared for it. + +68 Once an object has been created, its tag never changes. + +69 Class-wide types are defined to have unknown discriminants (see 3.7). This means that objects of a class-wide type +have to be explicitly initialized (whether created by an object_declaration or an allocator), and that aggregates have to be +explicitly qualified with a specific type when their expected type is class-wide. + +27 + +28 + +29 + +70 The capability provided by Tags.Generic_Dispatching_Constructor is sometimes known as a factory. + +30/2 + +71 13 December 2012 + +Tagged Types and Type Extensions 3.9 + + Ada Reference Manual — 2012 Edition + +Examples + +31 + +32 + +33 + +Examples of tagged record types: + +type Point is tagged + record + X, Y : Real := 0.0; + end record; +type Expression is tagged null record; + -- Components will be added by each extension + +3.9.1 Type Extensions + +1/2 + +Every type extension is a tagged type, and is a record extension or a private extension of some other +tagged type, or a noninterface synchronized tagged type. + +2 + +3/2 + +Syntax +record_extension_part ::= with record_definition + +Legality Rules + +The parent type of a record extension shall not be a class-wide type nor shall it be a synchronized tagged +type (see 3.9.4). If the parent type or any progenitor is nonlimited, then each of the components of the +record_extension_part shall be nonlimited. In addition to the places where Legality Rules normally apply +(see 12.3), these rules apply also in the private part of an instance of a generic unit. + +4/2 + +Within the body of a generic unit, or the body of any of its descendant library units, a tagged type shall not +be declared as a descendant of a formal type declared within the formal part of the generic unit. + +4.1/2 + +A record extension is a null extension if its declaration has no known_discriminant_part and its +record_extension_part includes no component_declarations. + +Static Semantics + +5 + +6 + +7/2 + +8 + +9 + +10 + +11 + +The elaboration of a record_extension_part consists of the elaboration of the record_definition. + +Dynamic Semantics + +NOTES +71 The term “type extension” refers to a type as a whole. The term “extension part” refers to the piece of text that defines +the additional components (if any) the type extension has relative to its specified ancestor type. + +72 When an extension is declared immediately within a body, primitive subprograms are inherited and are overridable, +but new primitive subprograms cannot be added. + +73 A name that denotes a component (including a discriminant) of the parent type is not allowed within the +record_extension_part. Similarly, a name that denotes a component defined within the record_extension_part is not +allowed within the record_extension_part. It is permissible to use a name that denotes a discriminant of the record +extension, providing there is a new known_discriminant_part in the enclosing type declaration. (The full rule is given in +3.8.) + +74 Each visible component of a record extension has to have a unique name, whether the component is (visibly) inherited +from the parent type or declared in the record_extension_part (see 8.3). + +Examples of record extensions (of types defined above in 3.9): + +Examples + +type Painted_Point is new Point with + record + Paint : Color := White; + end record; + -- Components X and Y are inherited + +3.9 Tagged Types and Type Extensions + +13 December 2012 72 + + Ada Reference Manual — 2012 Edition + +Origin : constant Painted_Point := (X | Y => 0.0, Paint => Black); +type Literal is new Expression with + record -- a leaf in an Expression tree + Value : Real; + end record; +type Expr_Ptr is access all Expression'Class; + -- see 3.10 +type Binary_Operation is new Expression with + record -- an internal node in an Expression tree + Left, Right : Expr_Ptr; + end record; +type Addition is new Binary_Operation with null record; +type Subtraction is new Binary_Operation with null record; + -- No additional components needed for these extensions +Tree : Expr_Ptr := -- A tree representation of “5.0 + (13.0–7.0)” + new Addition'( + Left => new Literal'(Value => 5.0), + Right => new Subtraction'( + Left => new Literal'(Value => 13.0), + Right => new Literal'(Value => 7.0))); + +3.9.2 Dispatching Operations of Tagged Types + +The primitive subprograms of a tagged type, the subprograms declared by formal_abstract_subprogram_- +declarations, and the stream attributes of a specific tagged type that are available (see 13.13.2) at the end +of the declaration list where the type is declared are called dispatching operations. A dispatching operation +can be called using a statically determined controlling tag, in which case the body to be executed is +determined at compile time. Alternatively, the controlling tag can be dynamically determined, in which +case the call dispatches to a body that is determined at run time; such a call is termed a dispatching call. +As explained below, the properties of the operands and the context of a particular call on a dispatching +operation determine how the controlling tag is determined, and hence whether or not the call is a +dispatching call. Run-time polymorphism is achieved when a dispatching operation is called by a +dispatching call. + +Static Semantics + +A call on a dispatching operation is a call whose name or prefix denotes the declaration of a dispatching +operation. A controlling operand in a call on a dispatching operation of a tagged type T is one whose +corresponding formal parameter is of type T or is of an anonymous access type with designated type T; the +corresponding formal parameter is called a controlling formal parameter. If the controlling formal +parameter is an access parameter, the controlling operand is the object designated by the actual parameter, +rather than the actual parameter itself. If the call is to a (primitive) function with result type T (a function +with a controlling result), then the call has a controlling result — the context of the call can control the +dispatching. Similarly, if the call is to a function with an access result type designating T (a function with a +controlling access result), then the call has a controlling access result, and the context can similarly +control dispatching. + +12 + +13 + +14 + +15 + +16 + +17 + +1/2 + +2/3 + +A name or expression of a tagged type is either statically tagged, dynamically tagged, or tag +indeterminate, according to whether, when used as a controlling operand, the tag that controls dispatching +is determined statically by the operand's (specific) type, dynamically by its tag at run time, or from +context. A qualified_expression or parenthesized expression is statically, dynamically, or indeterminately +tagged according to its operand. For other kinds of names and expressions, this is determined as follows: + +3 + +73 13 December 2012 + +Type Extensions 3.9.1 + + Ada Reference Manual — 2012 Edition + +4/2 + +5/2 + +6/2 + +7/1 + +8 + +9/1 + +10/2 + +• The name or expression is statically tagged if it is of a specific tagged type and, if it is a call +with a controlling result or controlling access result, it has at least one statically tagged +controlling operand; + +• The name or expression is dynamically tagged if it is of a class-wide type, or it is a call with a +controlling result or controlling access result and at least one dynamically tagged controlling +operand; + +• The name or expression is tag indeterminate if it is a call with a controlling result or controlling + +access result, all of whose controlling operands (if any) are tag indeterminate. + +A type_conversion is statically or dynamically tagged according to whether the type determined by the +subtype_mark is specific or class-wide, respectively. For an object that is designated by an expression +whose expected type is an anonymous access-to-specific tagged type, the object is dynamically tagged if +the expression, ignoring enclosing parentheses, is of the form X'Access, where X is of a class-wide type, +or is of the form new T'(...), where T denotes a class-wide subtype. Otherwise, the object is statically or +dynamically tagged according to whether the designated type of the type of the expression is specific or +class-wide, respectively. + +Legality Rules + +A call on a dispatching operation shall not have both dynamically tagged and statically tagged controlling +operands. + +If the expected type for an expression or name is some specific tagged type, then the expression or name +shall not be dynamically tagged unless it is a controlling operand in a call on a dispatching operation. +Similarly, if the expected type for an expression is an anonymous access-to-specific tagged type, then the +object designated by the expression shall not be dynamically tagged unless it is a controlling operand in a +call on a dispatching operation. + +In the declaration of a dispatching operation of a tagged type, everywhere a subtype of the tagged type +appears as a subtype of the profile (see 6.1), it shall statically match the first subtype of the tagged type. If +the dispatching operation overrides an inherited subprogram, it shall be subtype conformant with the +inherited subprogram. The convention of an inherited dispatching operation is the convention of the +corresponding primitive operation of the parent or progenitor type. The default convention of a dispatching +operation that overrides an inherited primitive operation is the convention of the inherited operation; if the +operation overrides multiple inherited operations, then they shall all have the same convention. An +explicitly declared dispatching operation shall not be of convention Intrinsic. + +11/2 + +The default_expression for a controlling formal parameter of a dispatching operation shall be tag indeter- +minate. + +11.1/2 + +If a dispatching operation is defined by a subprogram_renaming_declaration or the instantiation of a +generic subprogram, any access parameter of the renamed subprogram or the generic subprogram that +corresponds to a controlling access parameter of the dispatching operation, shall have a subtype that +excludes null. + +12 + +13 + +A given subprogram shall not be a dispatching operation of two or more distinct tagged types. + +The explicit declaration of a primitive subprogram of a tagged type shall occur before the type is frozen +(see 13.14). For example, new dispatching operations cannot be added after objects or values of the type +exist, nor after deriving a record extension from it, nor after a body. + +3.9.2 Dispatching Operations of Tagged Types + +13 December 2012 74 + + Ada Reference Manual — 2012 Edition + +Dynamic Semantics + +For the execution of a call on a dispatching operation of a type T, the controlling tag value determines +which subprogram body is executed. The controlling tag value is defined as follows: + +• If one or more controlling operands are statically tagged, then the controlling tag value is + +statically determined to be the tag of T. + +• If one or more controlling operands are dynamically tagged, then the controlling tag value is not +statically determined, but is rather determined by the tags of the controlling operands. If there is +more than one dynamically tagged controlling operand, a check is made that they all have the +same tag. If this check fails, Constraint_Error is raised unless the call is a function_call whose +name denotes the declaration of an equality operator (predefined or user defined) that returns +Boolean, in which case the result of the call is defined to indicate inequality, and no +subprogram_body is executed. This check is performed prior to evaluating any tag- +indeterminate controlling operands. + +• If all of the controlling operands (if any) are tag-indeterminate, then: + +• If the call has a controlling result or controlling access result and is itself, or designates, a +(possibly parenthesized or qualified) controlling operand of an enclosing call on a +dispatching operation of a descendant of type T, then its controlling tag value is determined +by the controlling tag value of this enclosing call; + +• If the call has a controlling result or controlling access result and (possibly parenthesized, +qualified, or dereferenced) is the expression of an assignment_statement whose target is +of a class-wide type, then its controlling tag value is determined by the target; + +• Otherwise, the controlling tag value is statically determined to be the tag of type T. + +For the execution of a call on a dispatching operation, the action performed is determined by the properties +of the corresponding dispatching operation of the specific type identified by the controlling tag value: + +• + +• + +• + +if the corresponding operation is explicitly declared for this type, even if the declaration occurs +in a private part, then the action comprises an invocation of the explicit body for the operation; + +if the corresponding operation is implicitly declared for this type and is implemented by an entry +or protected subprogram (see 9.1 and 9.4), then the action comprises a call on this entry or +protected subprogram, with the target object being given by the first actual parameter of the call, +and the actual parameters of the entry or protected subprogram being given by the remaining +actual parameters of the call, if any; + +if the corresponding operation is a predefined operator then the action comprises an invocation +of that operator; + +• otherwise, the action is the same as the action for the corresponding operation of the parent type +or progenitor type from which the operation was inherited except that additional invariant checks +(see 7.3.2) and class-wide postcondition checks (see 6.1.1) may apply. If there is more than one +such corresponding operation, the action is that for the operation that is not a null procedure, if +any; otherwise, the action is that of an arbitrary one of the operations. + +NOTES +75 The body to be executed for a call on a dispatching operation is determined by the tag; it does not matter whether that +tag is determined statically or dynamically, and it does not matter whether the subprogram's declaration is visible at the +place of the call. + +76 This subclause covers calls on dispatching subprograms of a tagged type. Rules for tagged type membership tests are +described in 4.5.2. Controlling tag determination for an assignment_statement is described in 5.2. + +77 A dispatching call can dispatch to a body whose declaration is not visible at the place of the call. + +14 + +15 + +16 + +17/2 + +18/2 + +18.1/2 + +19 + +20/3 + +20.1/3 + +20.2/3 + +20.3/3 + +20.4/3 + +21 + +22/2 + +23 + +75 13 December 2012 + +Dispatching Operations of Tagged Types 3.9.2 + + 24 + +1/2 + +1.1/3 + +Ada Reference Manual — 2012 Edition + +78 A call through an access-to-subprogram value is never a dispatching call, even if the access value designates a +dispatching operation. Similarly a call whose prefix denotes a subprogram_renaming_declaration cannot be a dispatching +call unless the renaming itself is the declaration of a primitive subprogram. + +3.9.3 Abstract Types and Subprograms + +An abstract type is a tagged type intended for use as an ancestor of other types, but which is not allowed to +have objects of its own. An abstract subprogram is a subprogram that has no body, but is intended to be +overridden at some point when inherited. Because objects of an abstract type cannot be created, a +dispatching call to an abstract subprogram always dispatches to some overriding body. + +abstract_subprogram_declaration ::= + [overriding_indicator] + subprogram_specification is abstract + [aspect_specification]; + +Syntax + +Static Semantics + +1.2/2 + +Interface types (see 3.9.4) are abstract types. In addition, a tagged type that has the reserved word abstract +in its declaration is an abstract type. The class-wide type (see 3.4.1) rooted at an abstract type is not itself +an abstract type. + +2/2 + +3/2 + +4/3 + +5/2 + +6/2 + +7 + +8/3 + +Only a tagged type shall have the reserved word abstract in its declaration. + +Legality Rules + +A subprogram declared by an abstract_subprogram_declaration or a formal_abstract_subprogram_- +declaration (see 12.6) is an abstract subprogram. If it is a primitive subprogram of a tagged type, then the +tagged type shall be abstract. + +If a type has an implicitly declared primitive subprogram that is inherited or is a predefined operator, and +the corresponding primitive subprogram of the parent or ancestor type is abstract or is a function with a +controlling access result, or if a type other than a nonabstract null extension inherits a function with a +controlling result, then: + +• If the type is abstract or untagged, the implicitly declared subprogram is abstract. +• Otherwise, the subprogram shall be overridden with a nonabstract subprogram or, in the case of +a private extension inheriting a function with a controlling result, have a full type that is a null +extension; for a type declared in the visible part of a package, the overriding may be either in the +visible or the private part. Such a subprogram is said to require overriding. However, if the type +is a generic formal type, the subprogram need not be overridden for the formal type itself; a +nonabstract version will necessarily be provided by the actual type. + +A call on an abstract subprogram shall be a dispatching call; nondispatching calls to an abstract +subprogram are not allowed. + +The type of an aggregate, or of an object created by an object_declaration or an allocator, or a generic +formal object of mode in, shall not be abstract. The type of the target of an assignment operation (see 5.2) +shall not be abstract. The type of a component shall not be abstract. If the result type of a function is +abstract, then the function shall be abstract. If a function has an access result type designating an abstract +type, then the function shall be abstract. The type denoted by a return_subtype_indication (see 6.5) shall +not be abstract. A generic function shall not have an abstract result type or an access result type +designating an abstract type. + +3.9.2 Dispatching Operations of Tagged Types + +13 December 2012 76 + + Ada Reference Manual — 2012 Edition + +If a partial view is not abstract, the corresponding full view shall not be abstract. If a generic formal type is +abstract, then for each primitive subprogram of the formal that is not abstract, the corresponding primitive +subprogram of the actual shall not be abstract. + +For an abstract type declared in a visible part, an abstract primitive subprogram shall not be declared in the +private part, unless it is overriding an abstract subprogram implicitly declared in the visible part. For a +tagged type declared in a visible part, a primitive function with a controlling result or a controlling access +result shall not be declared in the private part, unless it is overriding a function implicitly declared in the +visible part. + +9 + +10/3 + +A generic actual subprogram shall not be an abstract subprogram unless the generic formal subprogram is +declared by a formal_abstract_subprogram_declaration. The prefix of an attribute_reference for the +Access, Unchecked_Access, or Address attributes shall not denote an abstract subprogram. + +11/2 + +The elaboration of an abstract_subprogram_declaration has no effect. + +11.1/2 + +Dynamic Semantics + +NOTES +79 Abstractness is not inherited; to declare an abstract type, the reserved word abstract has to be used in the declaration +of the type extension. + +80 A class-wide type is never abstract. Even if a class is rooted at an abstract type, the class-wide type for the class is not +abstract, and an object of the class-wide type can be created; the tag of such an object will identify some nonabstract type +in the class. + +Example of an abstract type representing a set of natural numbers: + +Examples + +package Sets is + subtype Element_Type is Natural; + type Set is abstract tagged null record; + function Empty return Set is abstract; + function Union(Left, Right : Set) return Set is abstract; + function Intersection(Left, Right : Set) return Set is abstract; + function Unit_Set(Element : Element_Type) return Set is abstract; + procedure Take(Element : out Element_Type; + From : in out Set) is abstract; +end Sets; + +12 + +13 + +14 + +15 + +NOTES +81 Notes on the example: Given the above abstract type, one could then derive various (nonabstract) extensions of the +type, representing alternative implementations of a set. One might use a bit vector, but impose an upper bound on the +largest element representable, while another might use a hash table, trading off space for flexibility. + +16 + +3.9.4 Interface Types + +An interface type is an abstract tagged type that provides a restricted form of multiple inheritance. A +tagged type, task type, or protected type may have one or more interface types as ancestors. + +1/2 + +interface_type_definition ::= + [limited | task | protected | synchronized] interface [and interface_list] + +interface_list ::= interface_subtype_mark {and interface_subtype_mark} + +Syntax + +An interface type (also called an interface) is a specific abstract tagged type that is defined by an +interface_type_definition. + +Static Semantics + +77 13 December 2012 + +Abstract Types and Subprograms 3.9.3 + +2/2 + +3/2 + +4/2 + + Ada Reference Manual — 2012 Edition + +5/2 + +6/2 + +7/2 + +8/2 + +9/2 + +An interface with the reserved word limited, task, protected, or synchronized in its definition is termed, +respectively, a limited interface, a task interface, a protected interface, or a synchronized interface. In +addition, all task and protected interfaces are synchronized interfaces, and all synchronized interfaces are +limited interfaces. + +A task or protected type derived from an interface is a tagged type. Such a tagged type is called a +synchronized tagged type, as are synchronized interfaces and private extensions whose declaration +includes the reserved word synchronized. + +A task interface is an abstract task type. A protected interface is an abstract protected type. + +An interface type has no components. + +An interface_subtype_mark in an interface_list names a progenitor subtype; its type is the progenitor +type. An interface type inherits user-defined primitive subprograms from each progenitor type in the same +way that a derived type inherits user-defined primitive subprograms from its progenitor types (see 3.4). + +10/2 + +All user-defined primitive subprograms of an interface type shall be abstract subprograms or null +procedures. + +Legality Rules + +11/2 + +The type of a subtype named in an interface_list shall be an interface type. + +12/2 + +A type derived from a nonlimited interface shall be nonlimited. + +13/2 + +14/2 + +15/2 + +An interface derived from a task interface shall include the reserved word task in its definition; any other +type derived from a task interface shall be a private extension or a task type declared by a task declaration +(see 9.1). + +An interface derived from a protected interface shall include the reserved word protected in its definition; +any other type derived from a protected interface shall be a private extension or a protected type declared +by a protected declaration (see 9.4). + +An interface derived from a synchronized interface shall include one of the reserved words task, +protected, or synchronized in its definition; any other type derived from a synchronized interface shall be +a private extension, a task type declared by a task declaration, or a protected type declared by a protected +declaration. + +16/2 + +No type shall be derived from both a task interface and a protected interface. + +17/2 + +In addition to the places where Legality Rules normally apply (see 12.3), these rules apply also in the +private part of an instance of a generic unit. + +Dynamic Semantics + +18/3 + +The elaboration of an interface_type_definition creates the interface type and its first subtype. + +19/2 + +NOTES +82 Nonlimited interface types have predefined nonabstract equality operators. These may be overridden with user-defined +abstract equality operators. Such operators will then require an explicit overriding for any nonabstract descendant of the +interface. + +20/2 + +Example of a limited interface and a synchronized interface extending it: + +Examples + +3.9.4 Interface Types + +13 December 2012 78 + + Ada Reference Manual — 2012 Edition + +type Queue is limited interface; +procedure Append(Q : in out Queue; Person : in Person_Name) is abstract; +procedure Remove_First(Q : in out Queue; + Person : out Person_Name) is abstract; +function Cur_Count(Q : in Queue) return Natural is abstract; +function Max_Count(Q : in Queue) return Natural is abstract; +-- See 3.10.1 for Person_Name. +Queue_Error : exception; +-- Append raises Queue_Error if Cur_Count(Q) = Max_Count(Q) +-- Remove_First raises Queue_Error if Cur_Count(Q) = 0 +type Synchronized_Queue is synchronized interface and Queue; -- see 9.11 +procedure Append_Wait(Q : in out Synchronized_Queue; + Person : in Person_Name) is abstract; +procedure Remove_First_Wait(Q : in out Synchronized_Queue; + Person : out Person_Name) is abstract; +... +procedure Transfer(From : in out Queue'Class; + To : in out Queue'Class; + Number : in Natural := 1) is + Person : Person_Name; +begin + for I in 1..Number loop + Remove_First(From, Person); + Append(To, Person); + end loop; +end Transfer; + +This defines a Queue interface defining a queue of people. (A similar design could be created to define +any kind of queue simply by replacing Person_Name by an appropriate type.) The Queue interface has +four dispatching operations, Append, Remove_First, Cur_Count, and Max_Count. The body of a class- +wide operation, Transfer is also shown. Every nonabstract extension of Queue must provide +implementations for at least its four dispatching operations, as they are abstract. Any object of a type +derived from Queue may be passed to Transfer as either the From or the To operand. The two operands +need not be of the same type in any given call. + +The Synchronized_Queue interface inherits the four dispatching operations from Queue and adds two +additional dispatching operations, which wait if necessary rather than raising the Queue_Error exception. +This synchronized interface may only be implemented by a task or protected type, and as such ensures +safe concurrent access. + +Example use of the interface: + +type Fast_Food_Queue is new Queue with record ...; +procedure Append(Q : in out Fast_Food_Queue; Person : in Person_Name); +procedure Remove_First(Q : in out Fast_Food_Queue; Person : out +Person_Name); +function Cur_Count(Q : in Fast_Food_Queue) return Natural; +function Max_Count(Q : in Fast_Food_Queue) return Natural; +... + +Cashier, Counter : Fast_Food_Queue; + +... +-- Add George (see 3.10.1) to the cashier's queue: +Append (Cashier, George); +-- After payment, move George to the sandwich counter queue: +Transfer (Cashier, Counter); +... + +21/2 + +22/3 + +23/2 + +24/2 + +25/2 + +26/2 + +27/2 + +28/2 + +29/3 + +30/2 + +31/2 + +32/2 + +An interface such as Queue can be used directly as the parent of a new type (as shown here), or can be +used as a progenitor when a type is derived. In either case, the primitive operations of the interface are +inherited. For Queue, the implementation of the four inherited routines must be provided. Inside the call of + +33/2 + +79 13 December 2012 + +Interface Types 3.9.4 + + 34/2 + +35/2 + +36/2 + +1 + +2/2 + +3 + +4 + +5 + +5.1/2 + +6/2 + +7/1 + +8 + +9/3 + +Ada Reference Manual — 2012 Edition + +Transfer, calls will dispatch +Fast_Food_Queue. + +Example of a task interface: + +to + +the + +implementations of Append and Remove_First for + +type + +type Serial_Device is task interface; -- see 9.1 +procedure Read (Dev : in Serial_Device; C : out Character) is abstract; +procedure Write(Dev : in Serial_Device; C : in Character) is abstract; + +The Serial_Device interface has two dispatching operations which are intended to be implemented by task +entries (see 9.1). + +3.10 Access Types + +A value of an access type (an access value) provides indirect access to the object or subprogram it +designates. Depending on its type, an access value can designate either subprograms, objects created by +allocators (see 4.8), or more generally aliased objects of an appropriate type. + +Syntax + +access_type_definition ::= + [null_exclusion] access_to_object_definition + | [null_exclusion] access_to_subprogram_definition + +access_to_object_definition ::= + access [general_access_modifier] subtype_indication + +general_access_modifier ::= all | constant + +access_to_subprogram_definition ::= + access [protected] procedure parameter_profile + | access [protected] function parameter_and_result_profile + +null_exclusion ::= not null + +access_definition ::= + [null_exclusion] access [constant] subtype_mark + | [null_exclusion] access [protected] procedure parameter_profile + | [null_exclusion] access [protected] function parameter_and_result_profile + +Static Semantics + +There are two kinds of access types, access-to-object types, whose values designate objects, and access-to- +subprogram types, whose values designate subprograms. Associated with an access-to-object type is a +storage pool; several access types may share the same storage pool. All descendants of an access type +share the same storage pool. A storage pool is an area of storage used to hold dynamically allocated +objects (called pool elements) created by allocators; storage pools are described further in 13.11, “Storage +Management”. + +Access-to-object types are further subdivided into pool-specific access types, whose values can designate +only the elements of their associated storage pool, and general access types, whose values can designate +the elements of any storage pool, as well as aliased objects created by declarations rather than allocators, +and aliased subcomponents of other objects. + +A view of an object is defined to be aliased if it is defined by an object_declaration, component_- +definition, parameter_specification, or extended_return_object_declaration with the reserved word +aliased, or by a renaming of an aliased view. In addition, the dereference of an access-to-object value +denotes an aliased view, as does a view conversion (see 4.6) of an aliased view. The current instance of an + +3.9.4 Interface Types + +13 December 2012 80 + + Ada Reference Manual — 2012 Edition + +immutably limited type (see 7.5) is defined to be aliased. Finally, a formal parameter or generic formal +object of a tagged type is defined to be aliased. Aliased views are the ones that can be designated by an +access value. + +An access_to_object_definition defines an access-to-object type and its first subtype; the subtype_- +indication defines the designated subtype of the access type. If a general_access_modifier appears, then +the access type is a general access type. If the modifier is the reserved word constant, then the type is an +access-to-constant type; a designated object cannot be updated through a value of such a type. If the +modifier is the reserved word all, then the type is an access-to-variable type; a designated object can be +both read and updated through a value of such a type. If no general_access_modifier appears in the +access_to_object_definition, the access type is a pool-specific access-to-variable type. + +An access_to_subprogram_definition defines an access-to-subprogram type and its first subtype; the +parameter_profile or parameter_and_result_profile defines the designated profile of the access type. +There is a calling convention associated with the designated profile; only subprograms with this calling +convention can be designated by values of the access type. By default, the calling convention is +“protected” if the reserved word protected appears, and “Ada” otherwise. See Annex B for how to +override this default. + +An access_definition defines an anonymous general access type or an anonymous access-to-subprogram +type. For a general access type, the subtype_mark denotes its designated subtype; if the general_- +access_modifier constant appears, the type is an access-to-constant type; otherwise, it is an access-to- +variable type. For an access-to-subprogram type, the parameter_profile or parameter_and_result_profile +denotes its designated profile. + +For each access type, there is a null access value designating no entity at all, which can be obtained by +(implicitly) converting the literal null to the access type. The null value of an access type is the default +initial value of the type. Nonnull values of an access-to-object type are obtained by evaluating an +allocator, which returns an access value designating a newly created object (see 3.10.2), or in the case of a +general access-to-object type, evaluating an attribute_reference for the Access or Unchecked_Access +attribute of an aliased view of an object. Nonnull values of an access-to-subprogram type are obtained by +evaluating an attribute_reference for the Access attribute of a nonintrinsic subprogram. + +10 + +11 + +12/3 + +13/2 + +A null_exclusion in a construct specifies that the null value does not belong to the access subtype defined +by the construct, that is, the access subtype excludes null. In addition, the anonymous access subtype +defined by the access_definition for a controlling access parameter (see 3.9.2) excludes null. Finally, for a +subtype_indication without a null_exclusion, the subtype denoted by the subtype_indication excludes null +if and only if the subtype denoted by the subtype_mark in the subtype_indication excludes null. + +13.1/2 + +All subtypes of an access-to-subprogram type are constrained. The first subtype of a type defined by an +access_definition or an access_to_object_definition is unconstrained if the designated subtype is an +unconstrained array or discriminated subtype; otherwise, it is constrained. + +14/3 + +If a subtype_indication, discriminant_specification, parameter_specification, parameter_and_result_- +profile, object_renaming_declaration, or formal_object_declaration has a null_exclusion, the subtype_- +mark in that construct shall denote an access subtype that does not exclude null. + +14.1/2 + +Legality Rules + +A composite_constraint is compatible with an unconstrained access subtype if it is compatible with the +designated subtype. A null_exclusion is compatible with any access subtype that does not exclude null. An + +15/2 + +Dynamic Semantics + +81 13 December 2012 + +Access Types 3.10 + + Ada Reference Manual — 2012 Edition + +access value satisfies a composite_constraint of an access subtype if it equals the null value of its type or +if it designates an object whose value satisfies the constraint. An access value satisfies an exclusion of the +null value if it does not equal the null value of its type. + +16 + +The elaboration of an access_type_definition creates the access type and its first subtype. For an access- +to-object type, this elaboration includes the elaboration of the subtype_indication, which creates the +designated subtype. + +17/2 + +The elaboration of an access_definition creates an anonymous access type. + +18 + +19 + +20 + +NOTES +83 Access values are called “pointers” or “references” in some other languages. + +84 Each access-to-object type has an associated storage pool; several access types can share the same pool. An object can +be created in the storage pool of an access type by an allocator (see 4.8) for the access type. A storage pool (roughly) +corresponds to what some other languages call a “heap.” See 13.11 for a discussion of pools. + +85 Only index_constraints and discriminant_constraints can be applied to access types (see 3.6.1 and 3.7.1). + +21 + +Examples of access-to-object types: + +Examples + +22/2 + +23 + +24 + +25 + +26 + +type Peripheral_Ref is not null access Peripheral; -- see 3.8.1 +type Binop_Ptr is access all Binary_Operation'Class; + -- general access-to-class-wide, see 3.9.1 + +Example of an access subtype: + +subtype Drum_Ref is Peripheral_Ref(Drum); -- see 3.8.1 + +Example of an access-to-subprogram type: + +type Message_Procedure is access procedure (M : in String := "Error!"); +procedure Default_Message_Procedure(M : in String); +Give_Message : Message_Procedure := Default_Message_Procedure'Access; +... +procedure Other_Procedure(M : in String); +... +Give_Message := Other_Procedure'Access; +... +Give_Message("File not found."); -- call with parameter (.all is optional) +Give_Message.all; -- call with no parameters + +3.10.1 Incomplete Type Declarations + +1 + +There are no particular limitations on the designated type of an access type. In particular, the type of a +component of the designated type can be another access type, or even the same access type. This permits +mutually dependent and recursive access types. An incomplete_type_declaration can be used to introduce +a type to be used as a designated type, while deferring its full definition to a subsequent +full_type_declaration. + +2/2 + +incomplete_type_declaration ::= type defining_identifier [discriminant_part] [is tagged]; + +Syntax + +2.1/2 + +An incomplete_type_declaration declares an incomplete view of a type and its first subtype; the first +subtype is unconstrained if a discriminant_part appears. If the incomplete_type_declaration includes the +reserved word tagged, it declares a tagged incomplete view. An incomplete view of a type is a limited +view of the type (see 7.5). + +Static Semantics + +3.10 Access Types + +13 December 2012 82 + + Ada Reference Manual — 2012 Edition + +Given an access type A whose designated type T is an incomplete view, a dereference of a value of type A +also has this incomplete view except when: + +• +• + +• + +it occurs within the immediate scope of the completion of T, or + +it occurs within the scope of a nonlimited_with_clause that mentions a library package in whose +visible part the completion of T is declared, or + +it occurs within the scope of the completion of T and T is an incomplete view declared by an +incomplete_type_declaration. + +In these cases, the dereference has the view of T visible at the point of the dereference. + +Similarly, if a subtype_mark denotes a subtype_declaration defining a subtype of an incomplete view T, +the subtype_mark denotes an incomplete view except under the same three circumstances given above, in +which case it denotes the view of T visible at the point of the subtype_mark. + +Legality Rules + +An incomplete_type_declaration requires a completion, which shall be a type_declaration other than an +incomplete_type_declaration. If the incomplete_type_declaration occurs immediately within either the +visible part of a package_specification or a declarative_part, then the type_declaration shall occur later +and immediately within this visible part or declarative_part. If the incomplete_type_declaration occurs +immediately within the private part of a given package_specification, then the type_declaration shall +occur later and immediately within either the private part itself, or the declarative_part of the +corresponding package_body. + +If an incomplete_type_declaration includes the reserved word tagged, then a type_declaration that +completes it shall declare a tagged type. If an incomplete_type_declaration has a known_discriminant_- +part, then a type_declaration that completes it shall have a fully conforming (explicit) known_- +discriminant_part (see 6.3.1). If an incomplete_type_declaration has no discriminant_part (or an +unknown_discriminant_part), then a corresponding type_declaration is nevertheless allowed to have +discriminants, either explicitly, or inherited via derivation. + +A name that denotes an incomplete view of a type may be used as follows: + +• as the subtype_mark in the subtype_indication of an access_to_object_definition; the only +form of constraint allowed in this subtype_indication is a discriminant_constraint (a +null_exclusion is not allowed); + +• as the subtype_mark in the subtype_indication of a subtype_declaration; the subtype_- + +indication shall not have a null_exclusion or a constraint; + +• as the subtype_mark in an access_definition for an access-to-object type; +• as the subtype_mark defining the subtype of a parameter or result in a profile occurring within a + +basic_declaration; + +• as a generic actual parameter whose corresponding generic formal parameter is a formal + +incomplete type (see 12.5.1). + +If such a name denotes a tagged incomplete view, it may also be used: + +• as the subtype_mark defining the subtype of a parameter in the profile for a subprogram_body, + +entry_body, or accept_statement; + +• as the prefix of an attribute_reference whose attribute_designator is Class; such an attribute_- + +reference is restricted to the uses allowed here; it denotes a tagged incomplete view. + +This paragraph was deleted. + +2.2/2 + +2.3/2 + +2.4/3 + +2.5/3 + +2.6/3 + +2.7/3 + +3/3 + +4/3 + +5/2 + +6/3 + +7/2 + +8/3 + +8.1/3 + +8.2/3 + +8.3/2 + +8.4/3 + +9/2 + +9.1/3 + +83 13 December 2012 + +Incomplete Type Declarations 3.10.1 + + 9.2/3 + +9.3/2 + +Ada Reference Manual — 2012 Edition + +• This paragraph was deleted. + +If any of the above uses occurs as part of the declaration of a primitive subprogram of the incomplete +view, and the declaration occurs immediately within the private part of a package, then the completion of +the incomplete view shall also occur immediately within the private part; it shall not be deferred to the +package body. + +9.4/2 + +No other uses of a name that denotes an incomplete view of a type are allowed. + +10/3 + +A prefix that denotes an object shall not be of an incomplete view. An actual parameter in a call shall not +be of an untagged incomplete view. The result object of a function call shall not be of an incomplete view. +A prefix shall not denote a subprogram having a formal parameter of an untagged incomplete view, nor a +return type that is an incomplete view. + +Paragraph 11 was deleted. + +12 + +The elaboration of an incomplete_type_declaration has no effect. + +Dynamic Semantics + +13 + +13.1/3 + +14 + +15 + +16 + +17 + +18 + +19/2 + +20/2 + +21/2 + +NOTES +86 Within a declarative_part, an incomplete_type_declaration and a corresponding full_type_declaration cannot be +separated by an intervening body. This is because a type has to be completely defined before it is frozen, and a body +freezes all types declared prior to it in the same declarative_part (see 13.14). + +87 A name that denotes an object of an incomplete view is defined to be of a limited type. Hence, the target of an +assignment statement cannot be of an incomplete view. + +Example of a recursive type: + +Examples + +type Cell; -- incomplete type declaration +type Link is access Cell; +type Cell is + record + Value : Integer; + Succ : Link; + Pred : Link; + end record; +Head : Link := new Cell'(0, null, null); +Next : Link := Head.Succ; + +Examples of mutually dependent access types: + +type Person(<>); -- incomplete type declaration +type Car is tagged; -- incomplete type declaration +type Person_Name is access Person; +type Car_Name is access all Car'Class; +type Car is tagged + record + Number : Integer; + Owner : Person_Name; + end record; + +3.10.1 Incomplete Type Declarations + +13 December 2012 84 + + Ada Reference Manual — 2012 Edition + +type Person(Sex : Gender) is + record + Name : String(1 .. 20); + Birth : Date; + Age : Integer range 0 .. 130; + Vehicle : Car_Name; + case Sex is + when M => Wife : Person_Name(Sex => F); + when F => Husband : Person_Name(Sex => M); + end case; + end record; +My_Car, Your_Car, Next_Car : Car_Name := new Car; -- see 4.8 +George : Person_Name := new Person(M); + ... +George.Vehicle := Your_Car; + +22 + +23 + +3.10.2 Operations of Access Types + +The attribute Access is used to create access values designating aliased objects and nonintrinsic +subprograms. The “accessibility” rules prevent dangling references (in the absence of uses of certain +unchecked features — see Clause 13). + +1/3 + +For an attribute_reference with attribute_designator Access (or Unchecked_Access — see 13.10), the +expected type shall be a single access type A such that: + +2/2 + +Name Resolution Rules + +• A is an access-to-object type with designated type D and the type of the prefix is D'Class or is + +covered by D, or + +• A is an access-to-subprogram type whose designated profile is type conformant with that of the + +prefix. + +The prefix of such an attribute_reference is never interpreted as an implicit_dereference or a +parameterless function_call (see 4.1.4). The designated type or profile of the expected type of the +attribute_reference is the expected type or profile for the prefix. + +Static Semantics + +The accessibility rules, which prevent dangling references, are written in terms of accessibility levels, +which reflect the run-time nesting of masters. As explained in 7.6.1, a master is the execution of a certain +construct, such as a subprogram_body. An accessibility level is deeper than another if it is more deeply +nested at run time. For example, an object declared local to a called subprogram has a deeper accessibility +level than an object declared local to the calling subprogram. The accessibility rules for access types +require that the accessibility level of an object designated by an access value be no deeper than that of the +access type. This ensures that the object will live at least as long as the access type, which in turn ensures +that the access value cannot later designate an object that no longer exists. The Unchecked_Access +attribute may be used to circumvent the accessibility rules. + +2.1/2 + +2.2/2 + +2.3/2 + +3/2 + +A given accessibility level is said to be statically deeper than another if the given level is known at +compile time (as defined below) to be deeper than the other for all possible executions. In most cases, +accessibility is enforced at compile time by Legality Rules. Run-time accessibility checks are also used, +since the Legality Rules do not cover certain cases involving access parameters and generic packages. + +4 + +85 13 December 2012 + +Incomplete Type Declarations 3.10.1 + + Ada Reference Manual — 2012 Edition + +5 + +6 + +7/3 + +8 + +9/2 + +Each master, and each entity and view created by it, has an accessibility level: + +• The accessibility level of a given master is deeper than that of each dynamically enclosing +master, and deeper than that of each master upon which the task executing the given master +directly depends (see 9.3). + +• An entity or view defined by a declaration and created as part of its elaboration has the same +accessibility level as the innermost master of the declaration except in the cases of renaming and +derived access types described below. Other than for an explicitly aliased parameter, a formal +parameter of a callable entity has the same accessibility level as the master representing the +invocation of the entity. + +• The accessibility level of a view of an object or subprogram defined by a renaming_declaration + +is the same as that of the renamed view. + +• The accessibility level of a view conversion, qualified_expression, or parenthesized expression, + +is the same as that of the operand. + +9.1/3 + +• The accessibility level of a conditional_expression is the accessibility level of the evaluated + +dependent_expression. + +10/3 + +• The accessibility level of an aggregate that is used (in its entirety) to directly initialize part of +an object is that of the object being initialized. In other contexts, the accessibility level of an +aggregate is that of the innermost master that evaluates the aggregate. + +10.1/3 + +• The accessibility level of the result of a function call is that of the master of the function call, + +which is determined by the point of call as follows: + +10.2/3 + +• If the result is used (in its entirety) to directly initialize part of an object, the master is that +of the object being initialized. In the case where the initialized object is a coextension (see +below) that becomes a coextension of another object, the master is that of the eventual +object to which the coextension will be transferred. + +10.3/3 + +• If the result is of an anonymous access type and is the operand of an explicit conversion, + +the master is that of the target type of the conversion; + +10.4/3 + +• If the result is of an anonymous access type and defines an access discriminant, the master +is the same as that for an object created by an anonymous allocator that defines an access +discriminant (even if the access result is of an access-to-subprogram type). + +10.5/3 + +• If the call itself defines the result of a function to which one of the above rules applies, + +these rules are applied recursively; + +10.6/3 + +• In other cases, the master of the call is that of the innermost master that evaluates the + +function call. + +10.7/3 + +10.8/3 + +In the case of a call to a function whose result type is an anonymous access type, the +accessibility level of the type of the result of the function call is also determined by the point of +call as described above. + +• Within a return statement, the accessibility level of the return object is that of the execution of +the return statement. If the return statement completes normally by returning from the function, +then prior to leaving the function, the accessibility level of the return object changes to be a level +determined by the point of call, as does the level of any coextensions (see below) of the return +object. + +11 + +11.1/2 + +• The accessibility level of a derived access type is the same as that of its ultimate ancestor. +• The accessibility level of the anonymous access type defined by an access_definition of an + +object_renaming_declaration is the same as that of the renamed view. + +3.10.2 Operations of Access Types + +13 December 2012 86 + + + Ada Reference Manual — 2012 Edition + +• The accessibility level of the anonymous access type of an access discriminant in the +subtype_indication or qualified_expression of an allocator, or in the expression or return_- +subtype_indication of a return statement is determined as follows: + +• If the value of the access discriminant is determined by a discriminant_association in a +subtype_indication, the accessibility level of the object or subprogram designated by the +associated value (or library level if the value is null); + +• If the value of the access discriminant is determined by a default_expression in the +declaration of the discriminant, the level of the object or subprogram designated by the +associated value (or library level if null); + +• If the value of the access discriminant is determined by a record_component_association +in an aggregate, the accessibility level of the object or subprogram designated by the +associated value (or library level if the value is null); + +12/2 + +12.1/2 + +12.2/3 + +12.3/3 + +• In other cases, where the value of the access discriminant is determined by an object with + +12.4/3 + +an unconstrained nominal subtype, the accessibility level of the object. + +• The accessibility level of the anonymous access type of an access discriminant in any other + +12.5/3 + +context is that of the enclosing object. + +• The accessibility level of the anonymous access type of an access parameter specifying an +access-to-object type is the same as that of the view designated by the actual (or library-level if +the actual is null). + +• The accessibility level of the anonymous access type of an access parameter specifying an +access-to-subprogram type is deeper than that of any master; all such anonymous access types +have this same level. + +• The accessibility level of the type of a stand-alone object of an anonymous access-to-object type +is the same as the accessibility level of the type of the access value most recently assigned to the +object; accessibility checks ensure that this is never deeper than that of the declaration of the +stand-alone object. + +• The accessibility level of an explicitly aliased (see 6.1) formal parameter in a function body is +determined by the point of call; it is the same level that the return object ultimately will have. +• The accessibility level of an object created by an allocator is the same as that of the access type, +except for an allocator of an anonymous access type (an anonymous allocator) in certain +contexts, as follows: For an anonymous allocator that defines the result of a function with an +access result, the accessibility level is determined as though the allocator were in place of the +call of the function; in the special case of a call that is the operand of a type conversion, the level +is that of the target access type of the conversion. For an anonymous allocator defining the value +of an access parameter, the accessibility level is that of the innermost master of the call. For an +anonymous allocator whose type is that of a stand-alone object of an anonymous access-to- +object type, the accessibility level is that of the declaration of the stand-alone object. For one +defining an access discriminant, the accessibility level is determined as follows: + +• for an allocator used to define the discriminant of an object, the level of the object; + +• for an allocator used to define the constraint in a subtype_indication in any other context, + +the level of the master that elaborates the subtype_indication. + +• This paragraph was deleted. + +In the first case, the allocated object is said to be a coextension of the object whose discriminant +designates it, as well as of any object of which the discriminated object is itself a coextension or +subcomponent. If the allocated object is a coextension of an anonymous object representing the +result of an aggregate or function call that is used (in its entirety) to directly initialize a part of an +object, after the result is assigned, the coextension becomes a coextension of the object being + +13/3 + +13.1/2 + +13.2/3 + +13.3/3 + +14/3 + +14.1/3 + +14.2/3 + +14.3/3 + +14.4/3 + +87 13 December 2012 + +Operations of Access Types 3.10.2 + + + Ada Reference Manual — 2012 Edition + +initialized and is no longer considered a coextension of the anonymous object. All coextensions +of an object (which have not thus been transfered by such an initialization) are finalized when +the object is finalized (see 7.6.1). + +14.5/3 + +• Within a return statement, the accessibility level of the anonymous access type of an access + +result is that of the master of the call. + +15/3 + +• The accessibility level of a view of an object or subprogram designated by an access value is the + +same as that of the access type. + +16 + +• The accessibility level of a component, protected subprogram, or entry of (a view of) a + +composite object is the same as that of (the view of) the composite object. + +16.1/3 + +17 + +18 + +18.1/2 + +19/3 + +19.1/3 + +19.2/3 + +19.3/3 + +20 + +21 + +22 + +to be used + +In the above rules, the operand of a view conversion, parenthesized expression or qualified_expression is +considered +the view conversion, parenthesized expression or +if +that context. Similarly, a dependent_expression of a +qualified_expression +conditional_expression is considered to be used in a context if the conditional_expression itself is used in +that context. + +in a context +in + +is used + +itself + +One accessibility level is defined to be statically deeper than another in the following cases: + +• For a master that is statically nested within another master, the accessibility level of the inner + +master is statically deeper than that of the outer master. + +• The accessibility level of the anonymous access type of an access parameter specifying an +access-to-subprogram type is statically deeper than that of any master; all such anonymous +access types have this same level. + +• The statically deeper relationship does not apply to the accessibility level of the anonymous type +of an access parameter specifying an access-to-object type nor does it apply to a descendant of a +generic formal type; that is, such an accessibility level is not considered to be statically deeper, +nor statically shallower, than any other. + +• The statically deeper relationship does not apply to the accessibility level of the type of a stand- +alone object of an anonymous access-to-object type; that is, such an accessibility level is not +considered to be statically deeper, nor statically shallower, than any other. + +• Inside a return statement that applies to a function F, when determining whether the accessibility +level of an explicitly aliased parameter of F is statically deeper than the level of the return object +of F, the level of the return object is considered to be the same as that of the level of the +explicitly aliased parameter; for statically comparing with the level of other entities, an +explicitly aliased parameter of F is considered to have the accessibility level of the body of F. +• For determining whether a level is statically deeper than the level of the anonymous access type +of an access result of a function, when within a return statement that applies to the function, the +level of the master of the call is presumed to be the same as that of the level of the master that +elaborated the function body. + +• For determining whether one level is statically deeper than another when within a generic +package body, the generic package is presumed to be instantiated at the same level as where it +was declared; run-time checks are needed in the case of more deeply nested instantiations. +• For determining whether one level is statically deeper than another when within the declarative +region of a type_declaration, the current instance of the type is presumed to be an object created +at a deeper level than that of the type. + +The accessibility level of all library units is called the library level; a library-level declaration or entity is +one whose accessibility level is the library level. + +3.10.2 Operations of Access Types + +13 December 2012 88 + + Ada Reference Manual — 2012 Edition + +The following attribute is defined for a prefix X that denotes an aliased view of an object: + +X'Access + +X'Access yields an access value that designates the object denoted by X. The type of +X'Access is an access-to-object type, as determined by the expected type. The expected +type shall be a general access type. X shall denote an aliased view of an object, including +possibly the current instance (see 8.6) of a limited type within its definition, or a formal +parameter or generic formal object of a tagged type. The view denoted by the prefix X shall +satisfy the following additional requirements, presuming the expected type for X'Access is +the general access type A with designated type D: + +• If A is an access-to-variable type, then the view shall be a variable; on the other +hand, if A is an access-to-constant type, the view may be either a constant or a +variable. + +• The view shall not be a subcomponent that depends on discriminants of an object + +unless the object is known to be constrained. + +• If A is a named access type and D is a tagged type, then the type of the view shall +be covered by D; if A is anonymous and D is tagged, then the type of the view +shall be either D'Class or a type covered by D; if D is untagged, then the type of +the view shall be D, and either: + +• + +the designated subtype of A shall statically match the nominal subtype of the +view; or + +• D shall be discriminated in its full view and unconstrained in any partial +view, and the designated subtype of A shall be unconstrained. For the +purposes of determining within a generic body whether D is unconstrained in +any partial view, a discriminated subtype is considered to have a constrained +partial view if it is a descendant of an untagged generic formal private or +derived type. + +23 + +24/1 + +25 + +26/3 + +27/2 + +27.1/2 + +27.2/3 + +• The accessibility level of the view shall not be statically deeper than that of the + +28/3 + +access type A. + +In addition to the places where Legality Rules normally apply (see 12.3), these +requirements apply also in the private part of an instance of a generic unit. + +28.1/3 + +A check is made that the accessibility level of X is not deeper than that of the access type A. +If this check fails, Program_Error is raised. + +If the nominal subtype of X does not statically match the designated subtype of A, a view +conversion of X to the designated subtype is evaluated (which might raise Constraint_Error +— see 4.6) and the value of X'Access designates that view. + +The following attribute is defined for a prefix P that denotes a subprogram: + +P'Access + +P'Access yields an access value that designates the subprogram denoted by P. The type of +P'Access is an access-to-subprogram type (S), as determined by the expected type. The +accessibility level of P shall not be statically deeper than that of S. In addition to the places +where Legality Rules normally apply (see 12.3), this rule applies also in the private part of +an instance of a generic unit. The profile of P shall be subtype conformant with the +designated profile of S, and shall not be Intrinsic. If the subprogram denoted by P is +declared within a generic unit, and the expression P'Access occurs within the body of that +generic unit or within the body of a generic unit declared within the declarative region of +the generic unit, then the ultimate ancestor of S shall be either a nonformal type declared +within the generic unit or an anonymous access type of an access parameter. + +29 + +30 + +31 + +32/3 + +89 13 December 2012 + +Operations of Access Types 3.10.2 + + + + + Ada Reference Manual — 2012 Edition + +32.1/3 + +An expression is said to have distributed accessibility if it is + +Legality Rules + +32.2/3 + +32.3/3 + +32.4/3 + +32.5/3 + +33 + +34/2 + +35 + +36 + +37/2 + +38 + +39 + +40 + +41 + +• a conditional_expression (see 4.5.7); or +• a view conversion, qualified_expression, or parenthesized expression whose operand has + +distributed accessibility. + +The statically deeper relationship does not apply to the accessibility level of an expression having +distributed accessibility; that is, such an accessibility level is not considered to be statically deeper, nor +statically shallower, than any other. + +Any static accessibility requirement that is imposed on an expression that has distributed accessibility (or +on its type) is instead imposed on the dependent_expressions of the underlying conditional_expression. +This rule is applied recursively if a dependent_expression also has distributed accessibility. + +NOTES +88 The Unchecked_Access attribute yields the same result as the Access attribute for objects, but has fewer restrictions +(see 13.10). There are other predefined operations that yield access values: an allocator can be used to create an object, +and return an access value that designates it (see 4.8); evaluating the literal null yields a null access value that designates +no entity at all (see 4.2). + +89 The predefined operations of an access type also include the assignment operation, qualification, and membership +tests. Explicit conversion is allowed between general access types with matching designated subtypes; explicit conversion +is allowed between access-to-subprogram types with subtype conformant profiles (see 4.6). Named access types have +predefined equality operators; anonymous access types do not, but they can use the predefined equality operators for +universal_access (see 4.5.2). + +90 The object or subprogram designated by an access value can be named with a dereference, either an explicit_- +dereference or an implicit_dereference. See 4.1. + +91 A call through the dereference of an access-to-subprogram value is never a dispatching call. + +92 The Access attribute for subprograms and parameters of an anonymous access-to-subprogram type may together be +used to implement “downward closures” — that is, to pass a more-nested subprogram as a parameter to a less-nested +subprogram, as might be appropriate for an iterator abstraction or numerical integration. Downward closures can also be +implemented using generic formal subprograms (see 12.6). Note that Unchecked_Access is not allowed for subprograms. + +93 Note that using an access-to-class-wide tagged type with a dispatching operation is a potentially more structured +alternative to using an access-to-subprogram type. + +94 An implementation may consider two access-to-subprogram values to be unequal, even though they designate the +same subprogram. This might be because one points directly to the subprogram, while the other points to a special +prologue that performs an Elaboration_Check and then jumps to the subprogram. See 4.5.2. + +Example of use of the Access attribute: + +Examples + +Martha : Person_Name := new Person(F); -- see 3.10.1 +Cars : array (1..2) of aliased Car; + ... +Martha.Vehicle := Cars(1)'Access; +George.Vehicle := Cars(2)'Access; + +3.10.2 Operations of Access Types + +13 December 2012 90 + + Ada Reference Manual — 2012 Edition + +3.11 Declarative Parts + +A declarative_part contains declarative_items (possibly none). + +Syntax + +declarative_part ::= {declarative_item} + +declarative_item ::= + basic_declarative_item | body + +basic_declarative_item ::= + basic_declaration | aspect_clause | use_clause + +body ::= proper_body | body_stub + +proper_body ::= + subprogram_body | package_body | task_body | protected_body + +Static Semantics + +1 + +2 + +3 + +4/1 + +5 + +6 + +The list of declarative_items of a declarative_part is called the declaration list of the declarative_part. + +6.1/2 + +Dynamic Semantics + +The elaboration of a declarative_part consists of the elaboration of the declarative_items, if any, in the +order in which they are given in the declarative_part. + +An elaborable construct is in the elaborated state after the normal completion of its elaboration. Prior to +that, it is not yet elaborated. + +For a construct that attempts to use a body, a check (Elaboration_Check) is performed, as follows: + +• For a call to a (non-protected) subprogram that has an explicit body, a check is made that the +body is already elaborated. This check and the evaluations of any actual parameters of the call +are done in an arbitrary order. + +• For a call to a protected operation of a protected type (that has a body — no check is performed +if the protected type is imported — see B.1), a check is made that the protected_body is already +elaborated. This check and the evaluations of any actual parameters of the call are done in an +arbitrary order. + +• For the activation of a task, a check is made by the activator that the task_body is already +elaborated. If two or more tasks are being activated together (see 9.2), as the result of the +elaboration of a declarative_part or the initialization for the object created by an allocator, this +check is done for all of them before activating any of them. + +• For the instantiation of a generic unit that has a body, a check is made that this body is already +elaborated. This check and the evaluation of any explicit_generic_actual_parameters of the +instantiation are done in an arbitrary order. + +The exception Program_Error is raised if any of these checks fails. + +3.11.1 Completions of Declarations + +Declarations sometimes come in two parts. A declaration that requires a second part is said to require +completion. The second part is called the completion of the declaration (and of the entity declared), and is +is a body, an entry_body, a +either another declaration, a body, or a pragma. A body + +7 + +8 + +9 + +10/1 + +11/3 + +12 + +13 + +14 + +1/3 + +91 13 December 2012 + +Declarative Parts 3.11 + + Ada Reference Manual — 2012 Edition + +null_procedure_declaration or an expression_function_declaration that completes another declaration, or +a renaming-as-body (see 8.5.4). + +2 + +3 + +4 + +5 + +6/3 + +7 + +8 + +9/3 + +10 + +Name Resolution Rules + +A construct that can be a completion is interpreted as the completion of a prior declaration only if: +• The declaration and the completion occur immediately within the same declarative region; +• The defining name or defining_program_unit_name in the completion is the same as in the + +declaration, or in the case of a pragma, the pragma applies to the declaration; + +• If the declaration is overloadable, then the completion either has a type-conformant profile, or is + +a pragma. + +Legality Rules + +An implicit declaration shall not have a completion. For any explicit declaration that is specified to require +completion, there shall be a corresponding explicit completion, unless the declared entity is imported (see +B.1). + +At most one completion is allowed for a given declaration. Additional requirements on completions appear +where each kind of completion is defined. + +A type is completely defined at a place that is after its full type definition (if it has one) and after all of its +subcomponent types are completely defined. A type shall be completely defined before it is frozen (see +13.14 and 7.3). + +NOTES +95 Completions are in principle allowed for any kind of explicit declaration. However, for some kinds of declaration, the +only allowed completion is an implementation-defined pragma, and implementations are not required to have any such +pragmas. + +96 There are rules that prevent premature uses of declarations that have a corresponding completion. The +Elaboration_Checks of 3.11 prevent such uses at run time for subprograms, protected operations, tasks, and generic units. +The rules of 13.14, “Freezing Rules” prevent, at compile time, premature uses of other entities such as private types and +deferred constants. + +3.11.1 Completions of Declarations + +13 December 2012 92 + + Ada Reference Manual — 2012 Edition + +4 Names and Expressions + +The rules applicable to the different forms of name and expression, and to their evaluation, are given in +this clause. + +1/3 + +4.1 Names + +Names can denote declared entities, whether declared explicitly or implicitly (see 3.1). Names can also +denote objects or subprograms designated by access values; the results of type_conversions or +function_calls; subcomponents and slices of objects and values; protected subprograms, single entries, +entry families, and entries in families of entries. Finally, names can denote attributes of any of the +foregoing. + +Syntax + +name ::= + direct_name +| explicit_dereference + | indexed_component +| slice + | selected_component +| attribute_reference + | type_conversion +| function_call + | character_literal +| qualified_expression + | generalized_reference | generalized_indexing + +direct_name ::= identifier | operator_symbol + +prefix ::= name | implicit_dereference + +explicit_dereference ::= name.all + +implicit_dereference ::= name + +Certain forms of name (indexed_components, selected_components, slices, and attribute_references) +include a prefix that is either itself a name that denotes some related entity, or an implicit_dereference of +an access value that designates some related entity. + +1 + +2/3 + +3 + +4 + +5 + +6 + +7/3 + +The name in a dereference (either an implicit_dereference or an explicit_dereference) is expected to be +of any access type. + +8 + +Name Resolution Rules + +Static Semantics + +If the type of the name in a dereference is some access-to-object type T, then the dereference denotes a +view of an object, the nominal subtype of the view being the designated subtype of T. If the designated +subtype has unconstrained discriminants, the (actual) subtype of the view is constrained by the values of +the discriminants of the designated object, except when there is a partial view of the type of the designated +subtype that does not have discriminants, in which case the dereference is not constrained by its +discriminant values. + +9/3 + +If the type of the name in a dereference is some access-to-subprogram type S, then the dereference +denotes a view of a subprogram, the profile of the view being the designated profile of S. + +10 + +The evaluation of a name determines the entity denoted by the name. This evaluation has no other effect +for a name that is a direct_name or a character_literal. + +11/2 + +Dynamic Semantics + +93 13 December 2012 + +Names and Expressions 4 + + 12 + +13 + +14 + +15 + +16 + +17 + +1 + +2 + +3 + +4 + +5 + +6 + +7 + +Ada Reference Manual — 2012 Edition + +The evaluation of a name that has a prefix includes the evaluation of the prefix. The evaluation of a prefix +consists of the evaluation of the name or the implicit_dereference. The prefix denotes the entity denoted +by the name or the implicit_dereference. + +The evaluation of a dereference consists of the evaluation of the name and the determination of the object +or subprogram that is designated by the value of the name. A check is made that the value of the name is +not the null access value. Constraint_Error is raised if this check fails. The dereference denotes the object +or subprogram designated by the value of the name. + +Examples of direct names: + +Examples + +Pi +-- the direct name of a number +Limit -- the direct name of a constant +Count -- the direct name of a scalar variable +Board -- the direct name of an array variable +Matrix -- the direct name of a type +Random -- the direct name of a function +Error -- the direct name of an exception + +(see 3.3.2) +(see 3.3.1) +(see 3.3.1) +(see 3.6.1) +(see 3.6) +(see 6.1) +(see 11.1) + +Examples of dereferences: +Next_Car.all + -- the access variable Next_Car (see 3.10.1) +Next_Car.Owner -- selected component with implicit dereference; + -- same as Next_Car.all.Owner + +-- explicit dereference denoting the object designated by + +4.1.1 Indexed Components + +An indexed_component denotes either a component of an array or an entry in a family of entries. + +indexed_component ::= prefix(expression {, expression}) + +Syntax + +Name Resolution Rules + +The prefix of an indexed_component with a given number of expressions shall resolve to denote an array +(after any implicit dereference) with the corresponding number of index positions, or shall resolve to +denote an entry family of a task or protected object (in which case there shall be only one expression). + +The expected type for each expression is the corresponding index type. + +Static Semantics + +When the prefix denotes an array, the indexed_component denotes the component of the array with the +specified index value(s). The nominal subtype of the indexed_component is the component subtype of the +array type. + +When the prefix denotes an entry family, the indexed_component denotes the individual entry of the entry +family with the specified index value. + +Dynamic Semantics + +For the evaluation of an indexed_component, the prefix and the expressions are evaluated in an arbitrary +order. The value of each expression is converted to the corresponding index type. A check is made that +each index value belongs to the corresponding index range of the array or entry family denoted by the +prefix. Constraint_Error is raised if this check fails. + +4.1 Names + +13 December 2012 94 + + Ada Reference Manual — 2012 Edition + +Examples of indexed components: + +Examples + + My_Schedule(Sat) -- a component of a one-dimensional array (see 3.6.1) + Page(10) -- a component of a one-dimensional array (see 3.6) + Board(M, J + 1) -- a component of a two-dimensional array (see 3.6.1) + Page(10)(20) -- a component of a component + Request(Medium) -- an entry in a family of entries + Next_Frame(L)(M, N) -- a component of a function call + +(see 3.6) +(see 9.1) +(see 6.1) + +NOTES +1 Notes on the examples: Distinct notations are used for components of multidimensional arrays (such as Board) and +arrays of arrays (such as Page). The components of an array of arrays are arrays and can therefore be indexed. Thus +Page(10)(20) denotes the 20th component of Page(10). In the last example Next_Frame(L) is a function call returning an +access value that designates a two-dimensional array. + +4.1.2 Slices + +A slice denotes a one-dimensional array formed by a sequence of consecutive components of a one- +dimensional array. A slice of a variable is a variable; a slice of a constant is a constant; a slice of a value is +a value. + +slice ::= prefix(discrete_range) + +Syntax + +Name Resolution Rules + +The prefix of a slice shall resolve to denote a one-dimensional array (after any implicit dereference). + +The expected type for the discrete_range of a slice is the index type of the array type. + +A slice denotes a one-dimensional array formed by the sequence of consecutive components of the array +denoted by the prefix, corresponding to the range of values of the index given by the discrete_range. + +The type of the slice is that of the prefix. Its bounds are those defined by the discrete_range. + +Static Semantics + +Dynamic Semantics + +For the evaluation of a slice, the prefix and the discrete_range are evaluated in an arbitrary order. If the +slice is not a null slice (a slice where the discrete_range is a null range), then a check is made that the +bounds of the discrete_range belong to the index range of the array denoted by the prefix. +Constraint_Error is raised if this check fails. + +NOTES +2 A slice is not permitted as the prefix of an Access attribute_reference, even if the components or the array as a whole +are aliased. See 3.10.2. + +3 For a one-dimensional array A, the slice A(N .. N) denotes an array that has only one component; its type is the type of +A. On the other hand, A(N) denotes a component of the array A and has the corresponding component type. + +8 + +9 + +10 + +1 + +2 + +3 + +4 + +5 + +6 + +7 + +8 + +9 + +95 13 December 2012 + +Indexed Components 4.1.1 + + 10 + +11 + +1 + +2 + +3 + +4 + +5 + +6 + +7 + +8 + +9 + +Ada Reference Manual — 2012 Edition + +Examples of slices: + +Examples + + Stars(1 .. 15) -- a slice of 15 characters + Page(10 .. 10 + Size) -- a slice of 1 + Size components (see 3.6) +(see 3.6) + Page(L)(A .. B) -- a slice of the array Page(L) +(see 3.6.3) + Stars(1 .. 0) -- a null slice +(see 3.6.1 and 3.5.1) + My_Schedule(Weekday) -- bounds given by subtype + Stars(5 .. 15)(K) -- same as Stars(K) +(see 3.6.3) + -- provided that K is in 5 .. 15 + +(see 3.6.3) + +4.1.3 Selected Components + +Selected_components are used to denote components (including discriminants), entries, entry families, +and protected subprograms; they are also used as expanded names as described below. + +selected_component ::= prefix . selector_name + +selector_name ::= identifier | character_literal | operator_symbol + +Syntax + +Name Resolution Rules + +A selected_component is called an expanded name if, according to the visibility rules, at least one +possible interpretation of its prefix denotes a package or an enclosing named construct (directly, not +through a subprogram_renaming_declaration or generic_renaming_declaration). + +A selected_component that is not an expanded name shall resolve to denote one of the following: + +• A component (including a discriminant): + + The prefix shall resolve to denote an object or value of some non-array composite type (after any +implicit dereference). The selector_name shall resolve to denote a discriminant_specification of +the type, or, unless the type is a protected type, a component_declaration of the type. The +selected_component denotes the corresponding component of the object or value. + +• A single entry, an entry family, or a protected subprogram: + + The prefix shall resolve to denote an object or value of some task or protected type (after any +implicit dereference). The selector_name shall resolve to denote an entry_declaration or +subprogram_declaration occurring (implicitly or explicitly) within the visible part of that type. +The selected_component denotes the corresponding entry, entry family, or protected +subprogram. + +9.1/2 + +• A view of a subprogram whose first formal parameter is of a tagged type or is an access + +parameter whose designated type is tagged: + +9.2/3 + + The prefix (after any implicit dereference) shall resolve to denote an object or value of a specific +tagged type T or class-wide type T'Class. The selector_name shall resolve to denote a view of a +subprogram declared immediately within the declarative region in which an ancestor of the type +T is declared. The first formal parameter of the subprogram shall be of type T, or a class-wide +type that covers T, or an access parameter designating one of these types. The designator of the +subprogram shall not be the same as that of a component of the tagged type visible at the point +of the selected_component. The subprogram shall not be an implicitly declared primitive +operation of type T that overrides an inherited subprogram implemented by an entry or protected +subprogram visible at the point of the selected_component. The selected_component denotes +a view of this subprogram that omits the first formal parameter. This view is called a prefixed +view of the subprogram, and the prefix of the selected_component (after any implicit +dereference) is called the prefix of the prefixed view. + +4.1.2 Slices + +13 December 2012 96 + + Ada Reference Manual — 2012 Edition + +An expanded name shall resolve to denote a declaration that occurs immediately within a named +declarative region, as follows: + +• The prefix shall resolve to denote either a package (including the current instance of a generic + +package, or a rename of a package), or an enclosing named construct. + +• The selector_name shall resolve to denote a declaration that occurs immediately within the +declarative region of the package or enclosing construct (the declaration shall be visible at the +place of the expanded name — see 8.3). The expanded name denotes that declaration. + +• If the prefix does not denote a package, then it shall be a direct_name or an expanded name, and +it shall resolve to denote a program unit (other than a package), the current instance of a type, a +block_statement, a loop_statement, or an accept_statement (in the case of an accept_- +statement or entry_body, no family index is allowed); the expanded name shall occur within the +declarative region of this construct. Further, if this construct is a callable construct and the prefix +denotes more than one such enclosing callable construct, then the expanded name is ambiguous, +independently of the selector_name. + +10 + +11 + +12 + +13 + +Legality Rules + +For a subprogram whose first parameter is an access parameter, the prefix of any prefixed view shall +denote an aliased view of an object. + +13.1/2 + +For a subprogram whose first parameter is of mode in out or out, or of an anonymous access-to-variable +type, the prefix of any prefixed view shall denote a variable. + +13.2/2 + +The evaluation of a selected_component includes the evaluation of the prefix. + +Dynamic Semantics + +For a selected_component that denotes a component of a variant, a check is made that the values of the +discriminants are such that the value or object denoted by the prefix has this component. The exception +Constraint_Error is raised if this check fails. + +Examples of selected components: + +Examples + +(see 3.8) + Tomorrow.Month -- a record component +(see 3.10.1) + Next_Car.Owner -- a record component + Next_Car.Owner.Age -- a record component +(see 3.10.1) + -- the previous two lines involve implicit dereferences + Writer.Unit -- a record component (a discriminant) (see 3.8.1) + Min_Cell(H).Value -- a record component of the result + -- of the function call Min_Cell(H) + Cashier.Append -- a prefixed view of a procedure + Control.Seize -- an entry of a protected object + Pool(K).Write -- an entry of the task Pool(K) + +(see 3.9.4) +(see 9.4) +(see 9.4) + +(see 6.1) + +Examples of expanded names: + + Key_Manager."<" -- an operator of the visible part of a package (see 7.3.1) + Dot_Product.Sum -- a variable declared in a function body + Buffer.Pool -- a variable declared in a protected unit + Buffer.Read -- an entry of a protected unit + Swap.Temp -- a variable declared in a block statement + Standard.Boolean -- the name of a predefined type + +(see 6.1) +(see 9.11) +(see 9.11) +(see 5.6) +(see A.1) + +97 13 December 2012 + +Selected Components 4.1.3 + +14 + +15 + +16 + +17/2 + +18 + +19 + + Ada Reference Manual — 2012 Edition + +4.1.4 Attributes + +1 + +An attribute is a characteristic of an entity that can be queried via an attribute_reference or a range_- +attribute_reference. + +2 + +3/2 + +4 + +5 + +6 + +Syntax +attribute_reference ::= prefix'attribute_designator + +attribute_designator ::= + identifier[(static_expression)] + | Access | Delta | Digits | Mod + +range_attribute_reference ::= prefix'range_attribute_designator + +range_attribute_designator ::= Range[(static_expression)] + +Name Resolution Rules + +In an attribute_reference, if the attribute_designator is for an attribute defined for (at least some) objects +of an access type, then the prefix is never interpreted as an implicit_dereference; otherwise (and for all +range_attribute_references), if the type of the name within the prefix is of an access type, the prefix is +interpreted as an implicit_dereference. Similarly, if the attribute_designator is for an attribute defined for +(at least some) functions, then the prefix is never interpreted as a parameterless function_call; otherwise +(and for all range_attribute_references), if the prefix consists of a name that denotes a function, it is +interpreted as a parameterless function_call. + +7 + +The expression, if any, in an attribute_designator or range_attribute_designator is expected to be of any +integer type. + +8 + +The expression, if any, in an attribute_designator or range_attribute_designator shall be static. + +Legality Rules + +Static Semantics + +9/3 + +An attribute_reference denotes a value, an object, a subprogram, or some other kind of program entity. +For an attribute_reference that denotes a value or an object, if its type is scalar, then its nominal subtype +is the base subtype of the type; if its type is tagged, its nominal subtype is the first subtype of the type; +otherwise, its nominal subtype is a subtype of the type without any constraint or null_exclusion. Similarly, +unless explicitly specified otherwise, for an attribute_reference that denotes a function, when its result +type is scalar, its result subtype is the base subtype of the type, when its result type is tagged, the result +subtype is the first subtype of the type, and when the result type is some other type, the result subtype is a +subtype of the type without any constraint or null_exclusion. + +10 + +A range_attribute_reference X'Range(N) is equivalent to the range X'First(N) .. X'Last(N), except that +the prefix is only evaluated once. Similarly, X'Range is equivalent to X'First .. X'Last, except that the +prefix is only evaluated once. + +11 + +The evaluation of an attribute_reference (or range_attribute_reference) consists of the evaluation of the +prefix. + +Dynamic Semantics + +4.1.4 Attributes + +13 December 2012 98 + + Ada Reference Manual — 2012 Edition + +An implementation may provide implementation-defined attributes; the identifier for an implementation- +defined attribute shall differ from those of the language-defined attributes unless supplied for compatibility +with a previous edition of this International Standard. + +Implementation Permissions + +NOTES +4 Attributes are defined throughout this International Standard, and are summarized in K.2. + +5 In general, the name in a prefix of an attribute_reference (or a range_attribute_reference) has to be resolved without +using any context. However, in the case of the Access attribute, the expected type for the attribute_reference has to be a +single access type, and the resolution of the name can use the fact that the type of the object or the profile of the callable +entity denoted by the prefix has to match the designated type or be type conformant with the designated profile of the +access type. + +Examples of attributes: + +Examples + +Color'First -- minimum value of the enumeration type Color (see 3.5.1) +(see 3.5.1) +Rainbow'Base'First -- same as Color'First +Real'Digits -- precision of the type Real +(see 3.5.7) +Board'Last(2) -- upper bound of the second dimension of Board (see 3.6.1) +(see 3.6.1) +Board'Range(1) -- index range of the first dimension of Board +(see 9.1) +Pool(K)'Terminated -- True if task Pool(K) is terminated +(see 3.8) +Date'Size -- number of bits for records of type Date +(see 3.7.1) +Message'Address -- address of the record variable Message + +4.1.5 User-Defined References + +Static Semantics + +Given a discriminated type T, the following type-related operational aspect may be specified: + +Implicit_Dereference + +This aspect is specified by a name that denotes an access discriminant declared for the type +T. + +A (view of a) type with a specified Implicit_Dereference aspect is a reference type. A reference object is +an object of a reference type. The discriminant named by the Implicit_Dereference aspect is the reference +discriminant of the reference type or reference object. A generalized_reference is a name that identifies a +reference object, and denotes the object or subprogram designated by the reference discriminant of the +reference object. + +Syntax +generalized_reference ::= reference_object_name + +Name Resolution Rules + +The expected type for the reference_object_name in a generalized_reference is any reference type. + +Static Semantics + +A generalized_reference denotes a view equivalent to that of a dereference of the reference discriminant +of the reference object. + +Given a reference type T, the Implicit_Dereference aspect is inherited by descendants of type T if not +overridden. If a descendant type constrains the value of the reference discriminant of T by a new +discriminant, that new discriminant is the reference discriminant of the descendant. If the descendant type +constrains the value of the reference discriminant of T by an expression other than the name of a new + +12/1 + +13 + +14/2 + +15 + +16 + +1/3 + +2/3 + +3/3 + +4/3 + +5/3 + +6/3 + +7/3 + +99 13 December 2012 + +Attributes 4.1.4 + + + Ada Reference Manual — 2012 Edition + +8/3 + +9/3 + +10/3 + +11/3 + +12/3 + +13/3 + +14/3 + +15/3 + +1/3 + +2/3 + +discriminant, a generalized_reference that identifies an object of the descendant type denotes the object +or subprogram designated by the value of this constraining expression. + +Dynamic Semantics + +The evaluation of a generalized_reference consists of the evaluation of the reference_object_name and a +determination of the object or subprogram designated by the reference discriminant of the named reference +object. A check is made that the value of the reference discriminant is not the null access value. +Constraint_Error is raised if this check fails. The generalized_reference denotes the object or subprogram +designated by the value of the reference discriminant of the named reference object. + +Examples + +type Barrel is tagged ... -- holds objects of type Element +type Ref_Element(Data : access Element) is limited private + with Implicit_Dereference => Data; + -- This Ref_Element type is a "reference" type. + -- "Data" is its reference discriminant. +function Find (B : aliased in out Barrel; Key : String) return Ref_Element; + -- Return a reference to an element of a barrel. +B: aliased Barrel; +... +Find (B, "grape") := Element'(...); -- Assign through a reference. +-- This is equivalent to: +Find (B, "grape").Data.all := Element'(...); + +4.1.6 User-Defined Indexing + +Given a tagged type T, the following type-related, operational aspects may be specified: + +Static Semantics + +Constant_Indexing + +This aspect shall be specified by a name that denotes one or more functions declared +immediately within the same declaration list in which T is declared. All such functions shall +have at least two parameters, the first of which is of type T or T'Class, or is an access-to- +constant parameter with designated type T or T'Class. + +3/3 + +Variable_Indexing + +This aspect shall be specified by a name that denotes one or more functions declared +immediately within the same declaration list in which T is declared. All such functions shall +have at least two parameters, the first of which is of type T or T'Class, or is an access +parameter with designated type T or T'Class. All such functions shall have a return type that +is a reference type (see 4.1.5), whose reference discriminant is of an access-to-variable +type. + +4/3 + +5/3 + +These aspects are inherited by descendants of T (including the class-wide type T'Class). The aspects shall +not be overridden, but the functions they denote may be. + +An indexable container type is (a view of) a tagged type with at least one of the aspects Constant_Indexing +or Variable_Indexing specified. An indexable container object is an object of an indexable container type. +A generalized_indexing is a name that denotes the result of calling a function named by a +Constant_Indexing or Variable_Indexing aspect. + +4.1.5 User-Defined References + +13 December 2012 100 + + + + Ada Reference Manual — 2012 Edition + +The Constant_Indexing or Variable_Indexing aspect shall not be specified: + +• on a derived type if the parent type has the corresponding aspect specified or inherited; or +• on a full_type_declaration if the type has a tagged partial view. + +Legality Rules + +In addition to the places where Legality Rules normally apply (see 12.3), these rules apply also in the +private part of an instance of a generic unit. + +generalized_indexing ::= indexable_container_object_prefix actual_parameter_part + +Syntax + +Name Resolution Rules + +The expected type for the indexable_container_object_prefix of a generalized_indexing is any indexable +container type. + +If the Constant_Indexing aspect is specified for the type of the indexable_container_object_prefix of a +generalized_indexing, then the generalized_indexing is interpreted as a constant indexing under the +following circumstances: + +• when + +the Variable_Indexing + +aspect + +is + +not + +specified + +for + +the + +type + +of + +the + +indexable_container_object_prefix; + +• when the indexable_container_object_prefix denotes a constant; +• when the generalized_indexing is used within a primary where a name denoting a constant is + +permitted. + +Otherwise, the generalized_indexing is interpreted as a variable indexing. + +When a generalized_indexing is interpreted as a constant (or variable) indexing, it is equivalent to a call +on a prefixed view of one of the functions named by the Constant_Indexing (or Variable_Indexing) aspect +of the type of the indexable_container_object_prefix with the given actual_parameter_part, and with the +indexable_container_object_prefix as the prefix of the prefixed view. + +Examples + +type Indexed_Barrel is tagged ... + with Variable_Indexing => Find; + -- Indexed_Barrel is an indexable container type, + -- Find is the generalized indexing operation. +function Find (B : aliased in out Indexed_Barrel; Key : String) return +Ref_Element; + -- Return a reference to an element of a barrel (see 4.1.5). +IB: aliased Indexed_Barrel; +-- All of the following calls are then equivalent: +Find (IB,"pear").Data.all := Element'(...); -- Traditional call +IB.Find ("pear").Data.all := Element'(...); -- Call of prefixed view +IB.Find ("pear") := Element'(...); -- Implicit dereference (see 4.1.5) +IB ("pear") := Element'(...); -- Implicit indexing and dereference +IB ("pear").Data.all := Element'(...); -- Implicit indexing only + +6/3 + +7/3 + +8/3 + +9/3 + +10/3 + +11/3 + +12/3 + +13/3 + +14/3 + +15/3 + +16/3 + +17/3 + +18/3 + +19/3 + +20/3 + +21/3 + +101 13 December 2012 + +User-Defined Indexing 4.1.6 + + Ada Reference Manual — 2012 Edition + +4.2 Literals + +1 + +A literal represents a value literally, that is, by means of notation suited to its kind. A literal is either a +numeric_literal, a character_literal, the literal null, or a string_literal. + +2/2 + +This paragraph was deleted. + +Name Resolution Rules + +3 + +4 + +5 + +6 + +For a name that consists of a character_literal, either its expected type shall be a single character type, in +which case it is interpreted as a parameterless function_call that yields the corresponding value of the +character type, or its expected profile shall correspond to a parameterless function with a character result +type, in which case it is interpreted as the name of the corresponding parameterless function declared as +part of the character type's definition (see 3.5.1). In either case, the character_literal denotes the +enumeration_literal_specification. + +The expected type for a primary that is a string_literal shall be a single string type. + +Legality Rules + +A character_literal that is a name shall correspond to a defining_character_literal of the expected type, or +of the result type of the expected profile. + +For each character of a string_literal with a given expected string type, there shall be a corresponding +defining_character_literal of the component type of the expected string type. + +7/2 + +This paragraph was deleted. + +8/2 + +An integer literal is of type universal_integer. A real literal is of type universal_real. The literal null is of +type universal_access. + +Static Semantics + +9 + +10 + +11 + +12 + +The evaluation of a numeric literal, or the literal null, yields the represented value. + +Dynamic Semantics + +The evaluation of a string_literal that is a primary yields an array value containing the value of each +character of the sequence of characters of the string_literal, as defined in 2.6. The bounds of this array +value are determined according to the rules for positional_array_aggregates (see 4.3.3), except that for a +null string literal, the upper bound is the predecessor of the lower bound. + +For the evaluation of a string_literal of type T, a check is made that the value of each character of the +string_literal belongs to the component subtype of T. For the evaluation of a null string literal, a check is +made that its lower bound is greater than the lower bound of the base range of the index type. The +exception Constraint_Error is raised if either of these checks fails. + +NOTES +6 Enumeration literals that are identifiers rather than character_literals follow the normal rules for identifiers when used in +a name (see 4.1 and 4.1.3). Character_literals used as selector_names follow the normal rules for expanded names (see +4.1.3). + +4.2 Literals + +13 December 2012 102 + + Examples of literals: + +Examples + +Ada Reference Manual — 2012 Edition + +3.14159_26536 +1_345 +'A' +"Some Text" -- a string literal + +-- an integer literal +-- a character literal + +-- a real literal + +4.3 Aggregates + +An aggregate combines component values into a composite value of an array type, record type, or record +extension. + +aggregate ::= record_aggregate | extension_aggregate | array_aggregate + +Syntax + +Name Resolution Rules + +13 + +14 + +1 + +2 + +The expected type for an aggregate shall be a single array type, record type, or record extension. + +3/2 + +An aggregate shall not be of a class-wide type. + +Legality Rules + +Dynamic Semantics + +For the evaluation of an aggregate, an anonymous object is created and values for the components or +ancestor part are obtained (as described in the subsequent subclause for each kind of the aggregate) and +assigned into the corresponding components or ancestor part of the anonymous object. Obtaining the +values and the assignments occur in an arbitrary order. The value of the aggregate is the value of this +object. + +If an aggregate is of a tagged type, a check is made that its value belongs to the first subtype of the type. +Constraint_Error is raised if this check fails. + +4.3.1 Record Aggregates + +In a record_aggregate, a value is specified for each component of the record or record extension value, +using either a named or a positional association. + +Syntax + +record_aggregate ::= (record_component_association_list) + +record_component_association_list ::= + record_component_association {, record_component_association} + | null record + +record_component_association ::= + [component_choice_list =>] expression + | component_choice_list => <> + +component_choice_list ::= + component_selector_name {| component_selector_name} + | others + +A record_component_association is a named component association if it has a +component_choice_list; otherwise, it is a positional component association. Any positional + +4 + +5 + +6 + +1 + +2 + +3 + +4/2 + +5 + +6 + +103 13 December 2012 + +Literals 4.2 + + Ada Reference Manual — 2012 Edition + +component associations shall precede any named component associations. If there is a named +association with a component_choice_list of others, it shall come last. + +7 + +In the record_component_association_list for a record_aggregate, if there is only one association, +it shall be a named association. + +8/2 + +The expected type for a record_aggregate shall be a single record type or record extension. + +Name Resolution Rules + +9 + +10 + +11 + +12 + +13 + +14 + +15/3 + +16/3 + +For the record_component_association_list of a record_aggregate, all components of the composite +value defined by the aggregate are needed; for the association list of an extension_aggregate, only those +components not determined by the ancestor expression or subtype are needed (see 4.3.2). Each selector_- +name in a record_component_association shall denote a needed component (including possibly a +discriminant). + +The expected type for the expression of a record_component_association is the type of the associated +component(s); the associated component(s) are as follows: + +• For a positional association, the component (including possibly a discriminant) in the +corresponding relative position (in the declarative region of the type), counting only the needed +components; + +• For a named association with one or more component_selector_names, + +the named + +component(s); + +• For a named association with the reserved word others, all needed components that are not + +associated with some previous association. + +Legality Rules + +If the type of a record_aggregate is a record extension, then it shall be a descendant of a record type, +through one or more record extensions (and no private extensions). + +The reserved words null record may appear only if there are no components needed in a given record_- +component_association_list. + +Each record_component_association other than an others choice with a <> shall have at least one +associated component, and each needed component shall be associated with exactly one record_- +component_association. If a record_component_association with an expression has two or more +associated components, all of them shall be of the same type, or all of them shall be of anonymous access +types whose subtypes statically match. + +17/3 + +The value of a discriminant that governs a variant_part P shall be given by a static expression, unless P is +nested within a variant V that is not selected by the discriminant value governing the variant_part +enclosing V. + +17.1/2 + +A record_component_association for a discriminant without a default_expression shall have an +expression rather than <>. + +Dynamic Semantics + +18 + +19 + +The evaluation of a record_aggregate consists of the evaluation of the record_component_association_- +list. + +For the evaluation of a record_component_association_list, any per-object constraints (see 3.8) for +components specified in the association list are elaborated and any expressions are evaluated and +converted to the subtype of the associated component. Any constraint elaborations and expression + +4.3.1 Record Aggregates + +13 December 2012 104 + + Ada Reference Manual — 2012 Edition + +evaluations (and conversions) occur in an arbitrary order, except that the expression for a discriminant is +evaluated (and converted) prior to the elaboration of any per-object constraint that depends on it, which in +turn occurs prior to the evaluation and conversion of the expression for the component with the per-object +constraint. + +For a record_component_association with an expression, the expression defines the value for the +associated component(s). For a record_component_association with <>, if the component_declaration +has a default_expression, that default_expression defines the value for the associated component(s); +otherwise, the associated component(s) are initialized by default as for a stand-alone object of the +component subtype (see 3.3.1). + +19.1/2 + +The expression of a record_component_association is evaluated (and converted) once for each +associated component. + +NOTES +7 For a record_aggregate with positional associations, expressions specifying discriminant values appear first since the +known_discriminant_part is given first in the declaration of the type; they have to be in the same order as in the +known_discriminant_part. + +Example of a record aggregate with positional associations: + +(4, July, 1776) -- see 3.8 + +Examples + +Examples of record aggregates with named associations: +(Day => 4, Month => July, Year => 1776) +(Month => July, Day => 4, Year => 1776) +(Disk, Closed, Track => 5, Cylinder => 12) -- see 3.8.1 +(Unit => Disk, Status => Closed, Cylinder => 9, Track => 1) + +Examples of component associations with several choices: + +(Value => 0, Succ|Pred => new Cell'(0, null, null)) + -- The allocator is evaluated twice: Succ and Pred designate different cells +(Value => 0, Succ|Pred => <>) + -- Succ and Pred will be set to null + +-- see 3.10.1 + +-- see 3.10.1 + +Examples of record aggregates for tagged types (see 3.9 and 3.9.1): + +Expression'(null record) +Literal'(Value => 0.0) +Painted_Point'(0.0, Pi/2.0, Paint => Red) + +4.3.2 Extension Aggregates + +An extension_aggregate specifies a value for a type that is a record extension by specifying a value or +subtype for an ancestor of the type, followed by associations for any components not determined by the +ancestor_part. + +extension_aggregate ::= + (ancestor_part with record_component_association_list) + +ancestor_part ::= expression | subtype_mark + +Syntax + +20 + +21 + +22 + +23 + +24 + +25 + +26 + +27/2 + +28 + +29 + +29.1/2 + +29.2/2 + +30 + +31 + +1 + +2 + +3 + +105 13 December 2012 + +Record Aggregates 4.3.1 + + Ada Reference Manual — 2012 Edition + +4/2 + +The expected type for an extension_aggregate shall be a single type that is a record extension. If the +ancestor_part is an expression, it is expected to be of any tagged type. + +Name Resolution Rules + +5/3 + +5.1/3 + +5.2/3 + +5.3/3 + +5.4/3 + +6 + +7 + +8/3 + +9 + +10 + +11 + +12 + +Legality Rules + +If the ancestor_part is a subtype_mark, it shall denote a specific tagged subtype. If the ancestor_part is +an expression, it shall not be dynamically tagged. The type of the extension_aggregate shall be a +descendant of the type of the ancestor_part (the ancestor type), through one or more record extensions +(and no private extensions). If the ancestor_part is a subtype_mark, the view of the ancestor type from +which the type is descended (see 7.3.1) shall not have unknown discriminants. + +If the type of the ancestor_part is limited and at least one component is needed in the +record_component_association_list, then the ancestor_part shall not be: + +• a call to a function with an unconstrained result subtype; nor +• a parenthesized or qualified expression whose operand would violate this rule; nor +• a conditional_expression having at least one dependent_expression that would violate this rule. + +Static Semantics + +For the record_component_association_list of an extension_aggregate, the only components needed are +those of the composite value defined by the aggregate that are not inherited from the type of the +ancestor_part, plus any inherited discriminants if the ancestor_part is a subtype_mark that denotes an +unconstrained subtype. + +Dynamic Semantics + +For the evaluation of an extension_aggregate, the record_component_association_list is evaluated. If +the ancestor_part is an expression, it is also evaluated; if the ancestor_part is a subtype_mark, the +components of the value of the aggregate not given by the record_component_association_list are +initialized by default as for an object of the ancestor type. Any implicit initializations or evaluations are +performed in an arbitrary order, except that the expression for a discriminant is evaluated prior to any +other evaluation or initialization that depends on it. + +If the type of the ancestor_part has discriminants and the ancestor_part is not a subtype_mark that +denotes an unconstrained subtype, then a check is made that each discriminant determined by the +ancestor_part has the value specified for a corresponding discriminant, if any, either in the record_- +component_association_list, or in the derived_type_definition for some ancestor of the type of the +extension_aggregate. Constraint_Error is raised if this check fails. + +NOTES +8 If all components of the value of the extension_aggregate are determined by the ancestor_part, then the record_- +component_association_list is required to be simply null record. + +9 If the ancestor_part is a subtype_mark, then its type can be abstract. If its type is controlled, then as the last step of +evaluating the aggregate, the Initialize procedure of the ancestor type is called, unless the Initialize procedure is abstract +(see 7.6). + +Examples of extension aggregates (for types defined in 3.9.1): + +Painted_Point'(Point with Red) +(Point'(P) with Paint => Black) + +Examples + +4.3.2 Extension Aggregates + +13 December 2012 106 + + Ada Reference Manual — 2012 Edition + +(Expression with Left => 1.2, Right => 3.4) +Addition'(Binop with null record) + -- presuming Binop is of type Binary_Operation + +4.3.3 Array Aggregates + +In an array_aggregate, a value is specified for each component of an array, either positionally or by its +index. For a positional_array_aggregate, the components are given in increasing-index order, with a final +others, if any, representing any remaining components. For a named_array_aggregate, the components +are identified by the values covered by the discrete_choices. + +Syntax + +array_aggregate ::= + positional_array_aggregate | named_array_aggregate + +positional_array_aggregate ::= + (expression, expression {, expression}) + | (expression {, expression}, others => expression) + | (expression {, expression}, others => <>) + +named_array_aggregate ::= + (array_component_association {, array_component_association}) + +array_component_association ::= + discrete_choice_list => expression + | discrete_choice_list => <> + +An n-dimensional array_aggregate is one that is written as n levels of nested array_aggregates (or at the +bottom level, equivalent string_literals). For the multidimensional case (n >= 2) the array_aggregates (or +equivalent string_literals) at the n–1 lower levels are called subaggregates of the enclosing n-dimensional +array_aggregate. The expressions of the bottom level subaggregates (or of the array_aggregate itself if +one-dimensional) are called +the enclosing n-dimensional +the array component expressions of +array_aggregate. + +Name Resolution Rules + +The expected type for an array_aggregate (that is not a subaggregate) shall be a single array type. The +component type of this array type is the expected type for each array component expression of the +array_aggregate. + +The expected type for each discrete_choice in any discrete_choice_list of a named_array_aggregate is +the type of the corresponding index; the corresponding index for an array_aggregate that is not a +subaggregate is the first index of its type; for an (n–m)-dimensional subaggregate within an +array_aggregate of an n-dimensional type, the corresponding index is the index in position m+1. + +13 + +1 + +2 + +3/2 + +4 + +5/2 + +6 + +7/2 + +8 + +Legality Rules + +An array_aggregate of an n-dimensional array +array_aggregate. + +type shall be written as an n-dimensional + +9 + +An others choice is allowed for an array_aggregate only if an applicable index constraint applies to the +array_aggregate. An applicable index constraint is a constraint provided by certain contexts where an +array_aggregate is permitted that can be used to determine the bounds of the array value specified by the +aggregate. Each of the following contexts (and none other) defines an applicable index constraint: + +• For an explicit_actual_parameter, an explicit_generic_actual_parameter, the expression of a +return statement, the initialization expression in an object_declaration, or a default_expression + +10 + +11/2 + +107 13 December 2012 + +Extension Aggregates 4.3.2 + + Ada Reference Manual — 2012 Edition + +(for a parameter or a component), when the nominal subtype of the corresponding formal +parameter, generic formal parameter, function return object, object, or component is a +constrained array subtype, the applicable index constraint is the constraint of the subtype; + +12 + +13 + +14 + +• For the expression of an assignment_statement where the name denotes an array variable, the + +applicable index constraint is the constraint of the array variable; + +• For the operand of a qualified_expression whose subtype_mark denotes a constrained array + +subtype, the applicable index constraint is the constraint of the subtype; + +• For a component expression in an aggregate, if the component's nominal subtype is a + +constrained array subtype, the applicable index constraint is the constraint of the subtype; + +15/3 + +• For a parenthesized expression, the applicable index constraint is that, if any, defined for the + +expression; + +15.1/3 + +• For a conditional_expression, the applicable index constraint for each dependent_expression is + +that, if any, defined for the conditional_expression. + +16 + +17/3 + +18/3 + +19 + +20 + +21 + +22 + +23 + +The applicable index constraint applies to an array_aggregate that appears in such a context, as well as to +any subaggregates thereof. In the case of an explicit_actual_parameter (or default_expression) for a call +on a generic formal subprogram, no applicable index constraint is defined. + +The discrete_choice_list of an array_component_association is allowed to have a discrete_choice that is +a nonstatic choice_expression or that is a subtype_indication or range that defines a nonstatic or null +range, only if it is the single discrete_choice of its discrete_choice_list, and there is only one +array_component_association in the array_aggregate. + +In a named_array_aggregate where all discrete_choices are static, no two discrete_choices are allowed +to cover the same value (see 3.8.1); if there is no others choice, the discrete_choices taken together shall +exactly cover a contiguous sequence of values of the corresponding index type. + +A bottom level subaggregate of a multidimensional array_aggregate of a given array type is allowed to be +a string_literal only if the component type of the array type is a character type; each character of such a +string_literal shall correspond to a defining_character_literal of the component type. + +A subaggregate that is a string_literal is equivalent to one that is a positional_array_aggregate of the +same length, with each expression being the character_literal for the corresponding character of the +string_literal. + +Static Semantics + +Dynamic Semantics + +The evaluation of an array_aggregate of a given array type proceeds in two steps: + +1. Any discrete_choices of this aggregate and of its subaggregates are evaluated in an arbitrary + +order, and converted to the corresponding index type; + +2. The array component expressions of the aggregate are evaluated in an arbitrary order and their +values are converted to the component subtype of the array type; an array component expression +is evaluated once for each associated component. + +23.1/2 + +Each expression in an array_component_association defines the value for the associated component(s). +For an array_component_association with <>, the associated component(s) are initialized by default as +for a stand-alone object of the component subtype (see 3.3.1). + +24 + +The bounds of the index range of an array_aggregate (including a subaggregate) are determined as +follows: + +4.3.3 Array Aggregates + +13 December 2012 108 + + Ada Reference Manual — 2012 Edition + +• For an array_aggregate with an others choice, the bounds are those of the corresponding index + +range from the applicable index constraint; + +• For a positional_array_aggregate (or equivalent string_literal) without an others choice, the +lower bound is that of the corresponding index range in the applicable index constraint, if +defined, or that of the corresponding index subtype, if not; in either case, the upper bound is +determined from the lower bound and the number of expressions (or the length of the +string_literal); + +• For a named_array_aggregate without an others choice, the bounds are determined by the + +smallest and largest index values covered by any discrete_choice_list. + +For an array_aggregate, a check is made that the index range defined by its bounds is compatible with the +corresponding index subtype. + +25 + +26 + +27 + +28 + +For an array_aggregate with an others choice, a check is made that no expression or <> is specified for +an index value outside the bounds determined by the applicable index constraint. + +29/3 + +For a multidimensional array_aggregate, a check is made that all subaggregates that correspond to the +same index have the same bounds. + +The exception Constraint_Error is raised if any of the above checks fail. + +NOTES +10 In an array_aggregate, positional notation may only be used with two or more expressions; a single expression in +parentheses is interpreted as a parenthesized expression. A named_array_aggregate, such as (1 => X), may be used to +specify an array with a single component. + +Examples of array aggregates with positional associations: + +(7, 9, 5, 1, 3, 2, 4, 8, 6, 0) +Table'(5, 8, 4, 1, others => 0) -- see 3.6 + +Examples + +Examples of array aggregates with named associations: + +(1 .. 5 => (1 .. 8 => 0.0)) -- two-dimensional +(1 .. N => new Cell) -- N new cells, in particular for N = 0 +Table'(2 | 4 | 10 => 1, others => 0) +Schedule'(Mon .. Fri => True, others => False) -- see 3.6 +Schedule'(Wed | Sun => False, others => True) +Vector'(1 => 2.5) -- single-component vector + +Examples of two-dimensional array aggregates: + +-- Three aggregates for the same value of subtype Matrix(1..2,1..3) (see 3.6): +((1.1, 1.2, 1.3), (2.1, 2.2, 2.3)) +(1 => (1.1, 1.2, 1.3), 2 => (2.1, 2.2, 2.3)) +(1 => (1 => 1.1, 2 => 1.2, 3 => 1.3), 2 => (1 => 2.1, 2 => 2.2, 3 => 2.3)) + +Examples of aggregates as initial values: + +A : Table := (7, 9, 5, 1, 3, 2, 4, 8, 6, 0); -- A(1)=7, A(10)=0 +B : Table := (2 | 4 | 10 => 1, others => 0); -- B(1)=0, B(10)=1 +C : constant Matrix := (1 .. 5 => (1 .. 8 => 0.0)); -- C'Last(1)=5, C'Last(2)=8 +D : Bit_Vector(M .. N) := (M .. N => True); -- see 3.6 +E : Bit_Vector(M .. N) := (others => True); +F : String(1 .. 1) := (1 => 'F'); -- a one component aggregate: same as "F" + +30 + +31 + +32/3 + +33 + +34 + +35 + +36 + +37 + +38 + +39 + +40 + +41 + +42 + +43 + +109 13 December 2012 + +Array Aggregates 4.3.3 + + Ada Reference Manual — 2012 Edition + +Example of an array aggregate with defaulted others choice and with an applicable index constraint +provided by an enclosing record aggregate: + +Buffer'(Size => 50, Pos => 1, Value => String'('x', others => <>)) -- see 3.7 + +4.4 Expressions + +An expression is a formula that defines the computation or retrieval of a value. In this International +Standard, the term “expression” refers to a construct of the syntactic category expression or of any of the +following categories: choice_expression, choice_relation, relation, simple_expression, term, factor, +primary, conditional_expression, quantified_expression. + +expression ::= + relation {and relation} | relation {and then relation} + | relation {or relation} + | relation {xor relation} + +| relation {or else relation} + +Syntax + +choice_expression ::= + choice_relation {and choice_relation} + | choice_relation {or choice_relation} + | choice_relation {xor choice_relation} + | choice_relation {and then choice_relation} + | choice_relation {or else choice_relation} + +choice_relation ::= + simple_expression [relational_operator simple_expression] + +relation ::= + simple_expression [relational_operator simple_expression] + | simple_expression [not] in membership_choice_list + +membership_choice_list ::= membership_choice {| membership_choice} + +membership_choice ::= choice_expression | range | subtype_mark + +simple_expression ::= [unary_adding_operator] term {binary_adding_operator term} + +term ::= factor {multiplying_operator factor} + +factor ::= primary [** primary] | abs primary | not primary + +primary ::= + numeric_literal | null | string_literal | aggregate + | name | allocator | (expression) + | (conditional_expression) | (quantified_expression) + +A name used as a primary shall resolve to denote an object or a value. + +Name Resolution Rules + +Each expression has a type; it specifies the computation or retrieval of a value of that type. + +Static Semantics + +44/2 + +45/2 + +1/3 + +2 + +2.1/3 + +2.2/3 + +3/3 + +3.1/3 + +3.2/3 + +4 + +5 + +6 + +7/3 + +8 + +9 + +10 + +The value of a primary that is a name denoting an object is the value of the object. + +Dynamic Semantics + +4.3.3 Array Aggregates + +13 December 2012 110 + + Ada Reference Manual — 2012 Edition + +For the evaluation of a primary that is a name denoting an object of an unconstrained numeric subtype, if +the value of the object is outside the base range of its type, the implementation may either raise +Constraint_Error or return the value of the object. + +Implementation Permissions + +Examples + +Examples of primaries: + +4.0 -- real literal +Pi -- named number +(1 .. 10 => 0) -- array aggregate +Sum -- variable +Integer'Last -- attribute +Sine(X) -- function call +Color'(Blue) -- qualified expression +Real(M*N) -- conversion +(Line_Count + 10) -- parenthesized expression + +Examples of expressions: + +Volume -- primary +not Destroyed -- factor +2*Line_Count -- term +-4.0 -- simple expression +-4.0 + A -- simple expression +B**2 - 4.0*A*C -- simple expression +R*Sin(θ)*Cos(φ) -- simple expression +Password(1 .. 3) = "Bwv" -- relation +Count in Small_Int -- relation +Count not in Small_Int -- relation +Index = 0 or Item_Hit -- expression +(Cold and Sunny) or Warm -- expression (parentheses are required) +A**(B**C) -- expression (parentheses are required) + +4.5 Operators and Expression Evaluation + +The language defines the following six categories of operators (given in order of increasing precedence). +The corresponding operator_symbols, and only those, can be used as designators in declarations of +functions for user-defined operators. See 6.6, “Overloading of Operators”. + +logical_operator ::= + +relational_operator ::= + +binary_adding_operator ::= + +unary_adding_operator ::= + +Syntax + and | or | xor + + = | /= | < | <= | > | >= + + + | – | & + + + | – + +multiplying_operator ::= + + * | / | mod | rem + +highest_precedence_operator ::= + + ** | abs | not + +Static Semantics + +For a sequence of operators of the same precedence level, the operators are associated with their operands +in textual order from left to right. Parentheses can be used to impose specific associations. + +For each form of type definition, certain of the above operators are predefined; that is, they are implicitly +declared immediately after the type definition. For each such implicit operator declaration, the parameters +are called Left and Right for binary operators; the single parameter is called Right for unary operators. An + +111 13 December 2012 + +Expressions 4.4 + +11 + +12 + +13 + +14 + +15/2 + +1 + +2 + +3 + +4 + +5 + +6 + +7 + +8 + +9 + + Ada Reference Manual — 2012 Edition + +expression of the form X op Y, where op is a binary operator, is equivalent to a function_call of the form +"op"(X, Y). An expression of the form op Y, where op is a unary operator, is equivalent to a function_call +of the form "op"(Y). The predefined operators and their effects are described in subclauses 4.5.1 through +4.5.6. + +Dynamic Semantics + +The predefined operations on integer types either yield the mathematically correct result or raise the +exception Constraint_Error. For implementations that support the Numerics Annex, the predefined +operations on real types yield results whose accuracy is defined in Annex G, or raise the exception +Constraint_Error. + +Implementation Requirements + +The implementation of a predefined operator that delivers a result of an integer or fixed point type may +raise Constraint_Error only if the result is outside the base range of the result type. + +The implementation of a predefined operator that delivers a result of a floating point type may raise +Constraint_Error only if the result is outside the safe range of the result type. + +Implementation Permissions + +For a sequence of predefined operators of the same precedence level (and in the absence of parentheses +imposing a specific association), an implementation may impose any association of the operators with +operands so long as the result produced is an allowed result for the left-to-right association, but ignoring +the potential for failure of language-defined checks in either the left-to-right or chosen order of +association. + +NOTES +11 The two operands of an expression of the form X op Y, where op is a binary operator, are evaluated in an arbitrary +order, as for any function_call (see 6.4). + +Examples of precedence: + +Examples + +not Sunny or Warm -- same as (not Sunny) or Warm +X > 4.0 and Y > 0.0 -- same as (X > 4.0) and (Y > 0.0) +-4.0*A**2 -- same as –(4.0 * (A**2)) +abs(1 + A) + B -- same as (abs (1 + A)) + B +Y**(-3) -- parentheses are necessary +A / B * C -- same as (A/B)*C +A + (B + C) -- evaluate B + C before adding it to A + +4.5.1 Logical Operators and Short-circuit Control Forms + +An expression consisting of two relations connected by and then or or else (a short-circuit control form) +shall resolve to be of some boolean type; the expected type for both relations is that same boolean type. + +Name Resolution Rules + +The following logical operators are predefined for every boolean type T, for every modular type T, and for +every one-dimensional array type T whose component type is a boolean type: + +Static Semantics + +function "and"(Left, Right : T) return T +function "or" (Left, Right : T) return T +function "xor"(Left, Right : T) return T + +4.5 Operators and Expression Evaluation + +13 December 2012 112 + +10 + +11 + +12 + +13 + +14 + +15 + +16 + +17 + +1 + +2 + +3 + + Ada Reference Manual — 2012 Edition + +For boolean types, the predefined logical operators and, or, and xor perform the conventional operations +of conjunction, inclusive disjunction, and exclusive disjunction, respectively. + +For modular types, the predefined logical operators are defined on a bit-by-bit basis, using the binary +representation of the value of the operands to yield a binary representation for the result, where zero +represents False and one represents True. If this result is outside the base range of the type, a final +subtraction by the modulus is performed to bring the result into the base range of the type. + +The logical operators on arrays are performed on a component-by-component basis on matching +components (as for equality — see 4.5.2), using the predefined logical operator for the component type. +The bounds of the resulting array are those of the left operand. + +Dynamic Semantics + +The short-circuit control forms and then and or else deliver the same result as the corresponding +predefined and and or operators for boolean types, except that the left operand is always evaluated first, +and the right operand is not evaluated if the value of the left operand determines the result. + +For the logical operators on arrays, a check is made that for each component of the left operand there is a +matching component of the right operand, and vice versa. Also, a check is made that each component of +the result belongs to the component subtype. The exception Constraint_Error is raised if either of the +above checks fails. + +NOTES +12 The conventional meaning of the logical operators is given by the following truth table: + + A + +True +True +False +False + + B + +True +False +True +False + +(A and B) + +(A or B) + +(A xor B) + +True +False +False +False + +Examples + +True +True +True +False + +False +True +True +False + +Examples of logical operators: + +Sunny or Warm +Filter(1 .. 10) and Filter(15 .. 24) -- see 3.6.1 + +Examples of short-circuit control forms: + +Next_Car.Owner /= null and then Next_Car.Owner.Age > 25 -- see 3.10.1 +N = 0 or else A(N) = Hit_Value + +4.5.2 Relational Operators and Membership Tests + +The equality operators = (equals) and /= (not equals) are predefined for nonlimited types. The other +relational_operators are the ordering operators < (less than), <= (less than or equal), > (greater than), and +>= (greater than or equal). The ordering operators are predefined for scalar types, and for discrete array +types, that is, one-dimensional array types whose components are of a discrete type. + +A membership test, using in or not in, determines whether or not a value belongs to any given subtype or +range, is equal to any given value, has a tag that identifies a type that is covered by a given type, or is +convertible to and has an accessibility level appropriate for a given access type. Membership tests are +allowed for all types. + +4 + +5 + +6 + +7 + +8 + +9 + +10 + +11 + +12 + +13 + +14 + +1 + +2/3 + +113 13 December 2012 + +Logical Operators and Short-circuit Control Forms 4.5.1 + + + + + + + + Ada Reference Manual — 2012 Edition + +Name Resolution Rules + +3/3 + +3.1/3 + +tested + +type of a membership + +The +the +membership_choice_list. Either all membership_choices of the membership_choice_list shall resolve to +the same type, which is the tested type; or each membership_choice shall be of an elementary type, and +the tested type shall be covered by each of these elementary types. + +the membership_choices of + +is determined by + +test + +If the tested type is tagged, then the simple_expression shall resolve to be of a type that is convertible +(see 4.6) to the tested type; if untagged, the expected type for the simple_expression is the tested type. +The expected type of a choice_expression in a membership_choice, and of a simple_expression of a +range in a membership_choice, is the tested type of the membership operation. + +4 + +For a membership test, if the simple_expression is of a tagged class-wide type, then the tested type shall +be (visibly) tagged. + +4.1/3 + +If a membership test includes one or more choice_expressions and the tested type of the membership test +is limited, then the tested type of the membership test shall have a visible primitive equality operator. + +Legality Rules + +5 + +6 + +7 + +7.1/2 + +7.2/2 + +8 + +9 + +9.1/2 + +The result type of a membership test is the predefined type Boolean. + +Static Semantics + +The equality operators are predefined for every specific type T that is not limited, and not an anonymous +access type, with the following specifications: + +function "=" (Left, Right : T) return Boolean +function "/="(Left, Right : T) return Boolean + +The following additional equality operators for the universal_access type are declared in package Standard +for use with anonymous access types: + +function "=" (Left, Right : universal_access) return Boolean +function "/="(Left, Right : universal_access) return Boolean + +The ordering operators are predefined for every specific scalar type T, and for every discrete array type T, +with the following specifications: + +function "<" (Left, Right : T) return Boolean +function "<="(Left, Right : T) return Boolean +function ">" (Left, Right : T) return Boolean +function ">="(Left, Right : T) return Boolean + +Name Resolution Rules + +At least one of the operands of an equality operator for universal_access shall be of a specific anonymous +access type. Unless the predefined equality operator is identified using an expanded name with prefix +denoting the package Standard, neither operand shall be of an access-to-object type whose designated type +is D or D'Class, where D has a user-defined primitive equality operator such that: + +9.2/2 + +9.3/3 + +• +• + +its result type is Boolean; + +it is declared immediately within the same declaration list as D or any partial or incomplete view +of D; and + +9.4/2 + +• at least one of its operands is an access parameter with designated type D. + +9.5/2 + +At least one of the operands of the equality operators for universal_access shall be of type +universal_access, or both shall be of access-to-object types, or both shall be of access-to-subprogram +types. Further: + +Legality Rules + +4.5.2 Relational Operators and Membership Tests + +13 December 2012 114 + + Ada Reference Manual — 2012 Edition + +• When both are of access-to-object types, the designated types shall be the same or one shall +cover the other, and if the designated types are elementary or array types, then the designated +subtypes shall statically match; + +• When both are of access-to-subprogram types, the designated profiles shall be subtype + +conformant. + +If the profile of an explicitly declared primitive equality operator of an untagged record type is type +conformant with that of the corresponding predefined equality operator, the declaration shall occur before +the type is frozen. In addition, if the untagged record type has a nonlimited partial view, then the +declaration shall occur in the visible part of the enclosing package. In addition to the places where +Legality Rules normally apply (see 12.3), this rule applies also in the private part of an instance of a +generic unit. + +Dynamic Semantics + +For discrete types, the predefined relational operators are defined in terms of corresponding mathematical +operations on the position numbers of the values of the operands. + +For real types, the predefined relational operators are defined in terms of the corresponding mathematical +operations on the values of the operands, subject to the accuracy of the type. + +Two access-to-object values are equal if they designate the same object, or if both are equal to the null +value of the access type. + +Two access-to-subprogram values are equal if they are the result of the same evaluation of an Access +attribute_reference, or if both are equal to the null value of the access type. Two access-to-subprogram +values are unequal if they designate different subprograms. It is unspecified whether two access values +that designate +the result of distinct evaluations of Access +attribute_references are equal or unequal. + +the same subprogram but are + +9.6/2 + +9.7/2 + +9.8/3 + +10 + +11 + +12 + +13 + +For a type extension, predefined equality is defined in terms of the primitive (possibly user-defined) equals +operator for the parent type and for any components that have a record type in the extension part, and +predefined equality for any other components not inherited from the parent type. + +14/3 + +For a derived type whose parent is an untagged record type, predefined equality is defined in terms of the +primitive (possibly user-defined) equals operator of the parent type. + +14.1/3 + +For a private type, if its full type is a record type, predefined equality is defined in terms of the primitive +equals operator of the full type; otherwise, predefined equality for the private type is that of its full type. + +15/3 + +For other composite types, the predefined equality operators (and certain other predefined operations on +composite types — see 4.5.1 and 4.6) are defined in terms of the corresponding operation on matching +components, defined as follows: + +• For two composite objects or values of the same non-array type, matching components are those + +that correspond to the same component_declaration or discriminant_specification; + +• For two one-dimensional arrays of the same type, matching components are those (if any) whose +index values match in the following sense: the lower bounds of the index ranges are defined to +match, and the successors of matching indices are defined to match; + +• For two multidimensional arrays of the same type, matching components are those whose index + +values match in successive index positions. + +The analogous definitions apply if the types of the two objects or values are convertible, rather than being +the same. + +16 + +17 + +18 + +19 + +20 + +115 13 December 2012 + +Relational Operators and Membership Tests 4.5.2 + + Ada Reference Manual — 2012 Edition + +21 + +22 + +23 + +24/3 + +Given the above definition of matching components, the result of the predefined equals operator for +composite types (other than for those composite types covered earlier) is defined as follows: + +• If there are no components, the result is defined to be True; +• If there are unmatched components, the result is defined to be False; +• Otherwise, the result is defined in terms of the primitive equals operator for any matching +components that are records, and the predefined equals for any other matching components. + +24.1/3 + +If the primitive equals operator for an untagged record type is abstract, then Program_Error is raised at the +point of any (implicit) call to that abstract subprogram. + +24.2/1 + +For any composite type, the order in which "=" is called for components is unspecified. Furthermore, if the +result can be determined before calling "=" on some components, it is unspecified whether "=" is called on +those components. + +25 + +The predefined "/=" operator gives the complementary result to the predefined "=" operator. + +26/3 + +For a discrete array type, the predefined ordering operators correspond to lexicographic order using the +predefined order relation of the component type: A null array is lexicographically less than any array +having at least one component. In the case of nonnull arrays, the left operand is lexicographically less than +the right operand if the first component of the left operand is less than that of the right; otherwise, the left +operand is lexicographically less than the right operand only if their first components are equal and the tail +of the left operand is lexicographically less than that of the right (the tail consists of the remaining +components beyond the first and can be null). + +26.1/3 + +An individual membership test is the membership test of a single membership_choice. + +27/3 + +For the evaluation of a membership test using in whose membership_choice_list has a single +membership_choice, the simple_expression and the membership_choice are evaluated in an arbitrary +order; the result is the result of the individual membership test for the membership_choice. + +27.1/3 + +For the evaluation of a membership test using in whose membership_choice_list has more than one +membership_choice, the simple_expression of the membership test is evaluated first and the result of the +operation is equivalent to that of a sequence consisting of an individual membership test on each +membership_choice combined with the short-circuit control form or else. + +28/3 + +An individual membership test yields the result True if: + +28.1/3 + +• The membership_choice is a choice_expression, and the simple_expression is equal to the +value of the membership_choice. If the tested type is a record type or a limited type, the test +uses the primitive equality for the type; otherwise, the test uses predefined equality. + +28.2/3 + +• The membership_choice is a range and the value of the simple_expression belongs to the + +given range. + +29/3 + +30/3 + +30.1/2 + +• The membership_choice is a subtype_mark, the tested type is scalar, the value of the +simple_expression belongs to the range of the named subtype, and the predicate of the named +subtype evaluates to True. + +• The membership_choice is a subtype_mark, the tested type is not scalar, the value of the +simple_expression satisfies any constraints of the named subtype, the predicate of the named +subtype evaluates to True, and: + +• + +if the type of the simple_expression is class-wide, the value has a tag that identifies a type +covered by the tested type; + +4.5.2 Relational Operators and Membership Tests + +13 December 2012 116 + + Ada Reference Manual — 2012 Edition + +• + +• + +if the tested type is an access type and the named subtype excludes null, the value of the +simple_expression is not null; + +if the tested type is a general access-to-object type, the type of the simple_expression is +convertible to the tested type and its accessibility level is no deeper than that of the tested +type; further, if the designated type of the tested type is tagged and the simple_expression +is nonnull, the tag of the object designated by the value of the simple_expression is +covered by the designated type of the tested type. + +Otherwise, the test yields the result False. + +A membership test using not in gives the complementary result to the corresponding membership test +using in. + +30.2/3 + +30.3/3 + +31/3 + +32 + +For all nonlimited types declared in language-defined packages, the "=" and "/=" operators of the type +shall behave as if they were the predefined equality operators for the purposes of the equality of composite +types and generic formal types. + +32.1/1 + +Implementation Requirements + +NOTES +This paragraph was deleted. + +13 If a composite type has components that depend on discriminants, two values of this type have matching components +if and only if their discriminants are equal. Two nonnull arrays have matching components if and only if the length of +each dimension is the same for both. + +Examples of expressions involving relational operators and membership tests: + +Examples + +X /= Y +"" < "A" and "A" < "Aa" -- True +"Aa" < "B" and "A" < "A " -- True +My_Car = null -- True if My_Car has been set to null (see 3.10.1) +My_Car = Your_Car -- True if we both share the same car +My_Car.all = Your_Car.all -- True if the two cars are identical +N not in 1 .. 10 -- range membership test +Today in Mon .. Fri -- range membership test +Today in Weekday -- subtype membership test (see 3.5.1) +Card in Clubs | Spades -- list membership test (see 3.5.1) +Archive in Disk_Unit -- subtype membership test (see 3.8.1) +Tree.all in Addition'Class -- class membership test (see 3.9.1) + +4.5.3 Binary Adding Operators + +Static Semantics + +The binary adding operators + (addition) and – (subtraction) are predefined for every specific numeric +type T with their conventional meaning. They have the following specifications: + +function "+"(Left, Right : T) return T +function "-"(Left, Right : T) return T + +The concatenation operators & are predefined for every nonlimited, one-dimensional array type T with +component type C. They have the following specifications: + +function "&"(Left : T; Right : T) return T +function "&"(Left : T; Right : C) return T +function "&"(Left : C; Right : T) return T +function "&"(Left : C; Right : C) return T + +117 13 December 2012 + +Relational Operators and Membership Tests 4.5.2 + +33/2 + +34 + +35 + +36 + +37 + +38/3 + +39/3 + +1 + +2 + +3 + +4 + + Ada Reference Manual — 2012 Edition + +Dynamic Semantics + +For the evaluation of a concatenation with result type T, if both operands are of type T, the result of the +concatenation is a one-dimensional array whose length is the sum of the lengths of its operands, and whose +components comprise the components of the left operand followed by the components of the right +operand. If the left operand is a null array, the result of the concatenation is the right operand. Otherwise, +the lower bound of the result is determined as follows: + +• If the ultimate ancestor of the array type was defined by a constrained_array_definition, then + +the lower bound of the result is that of the index subtype; + +• If the ultimate ancestor of the array type was defined by an unconstrained_array_definition, + +then the lower bound of the result is that of the left operand. + +The upper bound is determined by the lower bound and the length. A check is made that the upper bound +of the result of the concatenation belongs to the range of the index subtype, unless the result is a null array. +Constraint_Error is raised if this check fails. + +If either operand is of the component type C, the result of the concatenation is given by the above rules, +using in place of such an operand an array having this operand as its only component (converted to the +component subtype) and having the lower bound of the index subtype of the array type as its lower bound. + +The result of a concatenation is defined in terms of an assignment to an anonymous object, as for any +function call (see 6.5). + +NOTES +14 As for all predefined operators on modular types, the binary adding operators + and – on modular types include a final +reduction modulo the modulus if the result is outside the base range of the type. + +Examples + +Examples of expressions involving binary adding operators: + +Z + 0.1 -- Z has to be of a real type +"A" & "BCD" -- concatenation of two string literals +'A' & "BCD" -- concatenation of a character literal and a string literal +'A' & 'A' -- concatenation of two character literals + +4.5.4 Unary Adding Operators + +Static Semantics + +The unary adding operators + (identity) and – (negation) are predefined for every specific numeric type T +with their conventional meaning. They have the following specifications: + +function "+"(Right : T) return T +function "-"(Right : T) return T + +NOTES +15 For modular integer types, the unary adding operator –, when given a nonzero operand, returns the result of +subtracting the value of the operand from the modulus; for a zero operand, the result is zero. + +4.5.5 Multiplying Operators + +Static Semantics + +The multiplying operators * (multiplication), / (division), mod (modulus), and rem (remainder) are +predefined for every specific integer type T: + +5 + +6 + +7 + +8 + +9 + +10 + +11 + +12 + +13 + +14 + +1 + +2 + +3 + +1 + +4.5.3 Binary Adding Operators + +13 December 2012 118 + + Ada Reference Manual — 2012 Edition + +function "*" (Left, Right : T) return T +function "/" (Left, Right : T) return T +function "mod"(Left, Right : T) return T +function "rem"(Left, Right : T) return T + +Signed integer multiplication has its conventional meaning. + +Signed integer division and remainder are defined by the relation: + +A = (A/B)*B + (A rem B) + +where (A rem B) has the sign of A and an absolute value less than the absolute value of B. Signed integer +division satisfies the identity: + +(-A)/B = -(A/B) = A/(-B) + +2 + +3 + +4 + +5 + +6 + +7 + +The signed integer modulus operator is defined such that the result of A mod B is either zero, or has the +sign of B and an absolute value less than the absolute value of B; in addition, for some signed integer +value N, this result satisfies the relation: + +8/3 + +A = B*N + (A mod B) + +The multiplying operators on modular types are defined in terms of the corresponding signed integer +operators, followed by a reduction modulo the modulus if the result is outside the base range of the type +(which is only possible for the "*" operator). + +Multiplication and division operators are predefined for every specific floating point type T: + +function "*"(Left, Right : T) return T +function "/"(Left, Right : T) return T + +The following multiplication and division operators, with an operand of the predefined type Integer, are +predefined for every specific fixed point type T: + +function "*"(Left : T; Right : Integer) return T +function "*"(Left : Integer; Right : T) return T +function "/"(Left : T; Right : Integer) return T + +All of the above multiplying operators are usable with an operand of an appropriate universal numeric +type. The following additional multiplying operators for root_real are predefined, and are usable when +both operands are of an appropriate universal or root numeric type, and the result is allowed to be of type +root_real, as in a number_declaration: + +function "*"(Left, Right : root_real) return root_real +function "/"(Left, Right : root_real) return root_real +function "*"(Left : root_real; Right : root_integer) return root_real +function "*"(Left : root_integer; Right : root_real) return root_real +function "/"(Left : root_real; Right : root_integer) return root_real + +Multiplication and division between any two fixed point types are provided by the following two +predefined operators: + +function "*"(Left, Right : universal_fixed) return universal_fixed +function "/"(Left, Right : universal_fixed) return universal_fixed + +9 + +10 + +11 + +12 + +13 + +14 + +15 + +16 + +17 + +18 + +19 + +Name Resolution Rules + +The above two fixed-fixed multiplying operators shall not be used in a context where the expected type for +the result is itself universal_fixed — the context has to identify some other numeric type to which the +result is to be converted, either explicitly or implicitly. Unless the predefined universal operator is +identified using an expanded name with prefix denoting the package Standard, an explicit conversion is +required on the result when using the above fixed-fixed multiplication operator if either operand is of a +type having a user-defined primitive multiplication operator such that: + +19.1/2 + +119 13 December 2012 + +Multiplying Operators 4.5.5 + + Ada Reference Manual — 2012 Edition + +19.2/3 + +• + +it is declared immediately within the same declaration list as the type or any partial or +incomplete view thereof; and + +19.3/2 + +• both of its formal parameters are of a fixed-point type. + +19.4/2 + +A corresponding requirement applies to the universal fixed-fixed division operator. + +Paragraph 20 was deleted. + +Dynamic Semantics + +The multiplication and division operators for real types have their conventional meaning. For floating +point types, the accuracy of the result is determined by the precision of the result type. For decimal fixed +point types, the result is truncated toward zero if the mathematical result is between two multiples of the +small of the specific result type (possibly determined by context); for ordinary fixed point types, if the +mathematical result is between two multiples of the small, it is unspecified which of the two is the result. + +The exception Constraint_Error is raised by integer division, rem, and mod if the right operand is zero. +Similarly, for a real type T with T'Machine_Overflows True, division by zero raises Constraint_Error. + +NOTES +16 For positive A and B, A/B is the quotient and A rem B is the remainder when A is divided by B. The following +relations are satisfied by the rem operator: + + A rem (-B) = A rem B + (-A) rem B = -(A rem B) + +17 For any signed integer K, the following identity holds: + A mod B = (A + K*B) mod B + +The relations between signed integer division, remainder, and modulus are illustrated by the following table: + + A B A/B A rem B A mod B A B A/B A rem B A mod B + 10 5 2 0 0 -10 5 -2 0 0 + 11 5 2 1 1 -11 5 -2 -1 4 + 12 5 2 2 2 -12 5 -2 -2 3 + 13 5 2 3 3 -13 5 -2 -3 2 + 14 5 2 4 4 -14 5 -2 -4 1 + A B A/B A rem B A mod B A B A/B A rem B A mod B + + 10 -5 -2 0 0 -10 -5 2 0 0 + 11 -5 -2 1 -4 -11 -5 2 -1 -1 + 12 -5 -2 2 -3 -12 -5 2 -2 -2 + 13 -5 -2 3 -2 -13 -5 2 -3 -3 + 14 -5 -2 4 -1 -14 -5 2 -4 -4 + +Examples of expressions involving multiplying operators: + +Examples + +I : Integer := 1; +J : Integer := 2; +K : Integer := 3; +X : Real := 1.0; -- see 3.5.7 +Y : Real := 2.0; +F : Fraction := 0.25; -- see 3.5.9 +G : Fraction := 0.5; + +21 + +22 + +23 + +24 + +25 + +26 + +27 + +28 + +29 + +30 + +31 + +32 + +33 + +34 + +4.5.5 Multiplying Operators + +13 December 2012 120 + + + Expression + +Value + +Result Type + +35 + +Ada Reference Manual — 2012 Edition + +I*J 2 +K/J 1 +1 +K mod J + +same as I and J, that is, Integer +same as K and J, that is, Integer +same as K and J, that is, Integer + +X/Y 0.5 +F/2 0.125 + +same as X and Y, that is, Real +same as F, that is, Fraction + +3*F 0.75 +0.75*G 0.375 + +Fraction(F*G) +Real(J)*Y + +0.125 +4.0 + +same as F, that is, Fraction +universal_fixed, implicitly convertible +to any fixed point type +Fraction, as stated by the conversion +Real, the type of both operands after +conversion of J + +4.5.6 Highest Precedence Operators + +Static Semantics + +The highest precedence unary operator abs (absolute value) is predefined for every specific numeric type +T, with the following specification: + +function "abs"(Right : T) return T + +The highest precedence unary operator not (logical negation) is predefined for every boolean type T, every +modular type T, and for every one-dimensional array type T whose components are of a boolean type, with +the following specification: + +function "not"(Right : T) return T + +The result of the operator not for a modular type is defined as the difference between the high bound of +the base range of the type and the value of the operand. For a binary modulus, this corresponds to a bit- +wise complement of the binary representation of the value of the operand. + +The operator not that applies to a one-dimensional array of boolean components yields a one-dimensional +boolean array with the same bounds; each component of the result is obtained by logical negation of the +corresponding component of the operand (that is, the component that has the same index value). A check +is made that each component of the result belongs to the component subtype; the exception +Constraint_Error is raised if this check fails. + +The highest precedence exponentiation operator ** is predefined for every specific integer type T with the +following specification: + +function "**"(Left : T; Right : Natural) return T + +Exponentiation is also predefined for every specific floating point type as well as root_real, with the +following specification (where T is root_real or the floating point type): + +function "**"(Left : T; Right : Integer'Base) return T + +The right operand of an exponentiation is the exponent. The value of X**N with the value of the exponent +N positive is the same as the value of X*X*...X (with N–1 multiplications) except that the multiplications +are associated in an arbitrary order. With N equal to zero, the result is one. With the value of N negative +(only defined for a floating point operand), the result is the reciprocal of the result using the absolute value +of N as the exponent. + +1 + +2 + +3 + +4 + +5 + +6 + +7 + +8 + +9 + +10 + +11/3 + +The implementation of exponentiation for the case of a negative exponent is allowed to raise +Constraint_Error if the intermediate result of the repeated multiplications is outside the safe range of the + +12 + +Implementation Permissions + +121 13 December 2012 + +Multiplying Operators 4.5.5 + + + + + + + Ada Reference Manual — 2012 Edition + +type, even though the final result (after taking the reciprocal) would not be. (The best machine +approximation to the final result in this case would generally be 0.0.) + +NOTES +18 As implied by the specification given above for exponentiation of an integer type, a check is made that the exponent is +not negative. Constraint_Error is raised if this check fails. + +4.5.7 Conditional Expressions + +A conditional_expression selects for evaluation at most one of the enclosed dependent_expressions, +depending on a decision among the alternatives. One kind of conditional_expression is the if_expression, +which selects for evaluation a dependent_expression depending on the value of one or more +corresponding conditions. The other kind of conditional_expression is the case_expression, which +selects for evaluation one of a number of alternative dependent_expressions; the chosen alternative is +determined by the value of a selecting_expression. + +conditional_expression ::= if_expression | case_expression + +Syntax + +if_expression ::= + if condition then dependent_expression + {elsif condition then dependent_expression} + [else dependent_expression] + +condition ::= boolean_expression + +case_expression ::= + case selecting_expression is + case_expression_alternative {, + case_expression_alternative} + +case_expression_alternative ::= + when discrete_choice_list => + dependent_expression + +Wherever the Syntax Rules allow an expression, a conditional_expression may be used in place of +the expression, so long as it is immediately surrounded by parentheses. + +Name Resolution Rules + +If a conditional_expression is expected to be of a type T, then each dependent_expression of the +conditional_expression is expected to be of type T. Similarly, if a conditional_expression is expected to +be of some class of types, then each dependent_expression of the conditional_expression is subject to the +same expectation. If a conditional_expression shall resolve +then each +dependent_expression shall resolve to be of type T. + +to be of a + +type T, + +13 + +1/3 + +2/3 + +3/3 + +4/3 + +5/3 + +6/3 + +7/3 + +8/3 + +9/3 + +The possible types of a conditional_expression are further determined as follows: + +10/3 + +• If the conditional_expression is the operand of a type conversion, the type of the + +conditional_expression is the target type of the conversion; otherwise, + +11/3 + +• If all of the dependent_expressions are of the same type, the type of the conditional_expression + +is that type; otherwise, + +12/3 + +• If a dependent_expression is of an elementary type, the type of the conditional_expression + +shall be covered by that type; otherwise, + +13/3 + +• If the conditional_expression is expected to be of type T or shall resolve to type T, then the + +conditional_expression is of type T. + +4.5.6 Highest Precedence Operators + +13 December 2012 122 + + Ada Reference Manual — 2012 Edition + +A condition is expected to be of any boolean type. + +The expected type for the selecting_expression and the discrete_choices are as for case statements (see +5.4). + +14/3 + +15/3 + +All of the dependent_expressions shall be convertible (see 4.6) to the type of the conditional_expression. + +16/3 + +Legality Rules + +the expected + +type of a conditional_expression + +the +If +dependent_expressions of the conditional_expression shall be dynamically tagged, or none shall be +dynamically tagged. In this case, the conditional_expression is dynamically tagged if all of the +dependent_expressions are dynamically tagged, is tag-indeterminate if all of the dependent_expressions +are tag-indeterminate, and is statically tagged otherwise. + +is a specific + +type, all of + +tagged + +If there is no else dependent_expression, the if_expression shall be of a boolean type. + +All Legality Rules that apply to the discrete_choices of a case_statement (see 5.4) also apply to the +discrete_choices of a case_expression except within an instance of a generic unit. + +Dynamic Semantics + +For the evaluation of an if_expression, the condition specified after if, and any conditions specified after +elsif, are evaluated in succession (treating a final else as elsif True then), until one evaluates to True or all +conditions are evaluated and yield False. If a condition evaluates +the associated +dependent_expression is evaluated, converted to the type of the if_expression, and the resulting value is +the value of the if_expression. Otherwise (when there is no else clause), the value of the if_expression is +True. + +to True, + +For the evaluation of a case_expression, the selecting_expression is first evaluated. If the value of the +selecting_expression is covered by the discrete_choice_list of some case_expression_alternative, then +the dependent_expression of the case_expression_alternative is evaluated, converted to the type of the +case_expression, and the resulting value is the value of the case_expression. Otherwise (the value is not +covered by any discrete_choice_list, perhaps due to being outside the base range), Constraint_Error is +raised. + +4.5.8 Quantified Expressions + +quantified_expression ::= for quantifier loop_parameter_specification => predicate + | for quantifier iterator_specification => predicate + +Syntax + +quantifier ::= all | some + +predicate ::= boolean_expression + +Wherever the Syntax Rules allow an expression, a quantified_expression may be used in place of +the expression, so long as it is immediately surrounded by parentheses. + +Name Resolution Rules + +17/3 + +18/3 + +19/3 + +20/3 + +21/3 + +1/3 + +2/3 + +3/3 + +4/3 + +The expected +quantified_expression is expected to be of the same type. + +type of a quantified_expression + +is any Boolean + +type. The predicate + +in a + +5/3 + +123 13 December 2012 + +Conditional Expressions 4.5.7 + + Ada Reference Manual — 2012 Edition + +Dynamic Semantics + +6/3 + +7/3 + +8/3 + +9/3 + +10/3 + +11/3 + +12/3 + +13/3 + +1/3 + +2 + +3 + +4/3 + +5/2 + +6 + +7 + +For the evaluation of a quantified_expression, the loop_parameter_specification or iterator_specification +is first elaborated. The evaluation of a quantified_expression then evaluates the predicate for each value +the +of +loop_parameter_specification (see 5.5) or iterator_specification (see 5.5.2). + +loop parameter. These values + +are examined + +specified by + +the order + +the + +in + +The value of the quantified_expression is determined as follows: + +• If the quantifier is all, the expression is True if the evaluation of the predicate yields True for +each value of the loop parameter. It is False otherwise. Evaluation of the quantified_expression +stops when all values of the domain have been examined, or when the predicate yields False for +a given value. Any exception raised by evaluation of the predicate is propagated. + +• If the quantifier is some, the expression is True if the evaluation of the predicate yields True for +some value of the loop parameter. It is False otherwise. Evaluation of the quantified_expression +stops when all values of the domain have been examined, or when the predicate yields True for +a given value. Any exception raised by evaluation of the predicate is propagated. + +Examples + +The postcondition for a sorting routine on an array A with an index subtype T can be written: + +Post => (A'Length < 2 or else + (for all I in A'First .. T'Pred(A'Last) => A (I) <= A (T'Succ (I)))) + +The assertion that a positive number is composite (as opposed to prime) can be written: +pragma Assert (for some X in 2 .. N / 2 => N mod X = 0); + +4.6 Type Conversions + +Explicit type conversions, both value conversions and view conversions, are allowed between closely +related types as defined below. This subclause also defines rules for value and view conversions to a +particular subtype of a type, both explicit ones and those implicit in other constructs. + +type_conversion ::= + subtype_mark(expression) + | subtype_mark(name) + +Syntax + +The target subtype of a type_conversion is the subtype denoted by the subtype_mark. The operand of a +type_conversion is the expression or name within the parentheses; its type is the operand type. + +One type is convertible to a second type if a type_conversion with the first type as operand type and the +second type as target type is legal according to the rules of this subclause. Two types are convertible if +each is convertible to the other. + +A type_conversion whose operand is the name of an object is called a view conversion if both its target +type and operand type are tagged, or if it appears in a call as an actual parameter of mode out or in out; +other type_conversions are called value conversions. + +The operand of a type_conversion is expected to be of any type. + +Name Resolution Rules + +The operand of a view conversion is interpreted only as a name; the operand of a value conversion is +interpreted as an expression. + +4.5.8 Quantified Expressions + +13 December 2012 124 + + Ada Reference Manual — 2012 Edition + +In a view conversion for an untagged type, the target type shall be convertible (back) to the operand type. + +8/2 + +Legality Rules + +Paragraphs 9 through 20 were reorganized and moved below. + +If there is a type (other than a root numeric type) that is an ancestor of both the target type and the operand +type, or both types are class-wide types, then at least one of the following rules shall apply: + +21/3 + +• The target type shall be untagged; or +• The operand type shall be covered by or descended from the target type; or +• The operand type shall be a class-wide type that covers the target type; or +• The operand and target types shall both be class-wide types and the specific type associated with + +21.1/2 + +22 + +23/2 + +23.1/2 + +at least one of them shall be an interface type. + +If there is no type (other than a root numeric type) that is the ancestor of both the target type and the +operand type, and they are not both class-wide types, one of the following rules shall apply: + +24/3 + +• If the target type is a numeric type, then the operand type shall be a numeric type. +• If the target type is an array type, then the operand type shall be an array type. Further: + +• The types shall have the same dimensionality; + +• Corresponding index types shall be convertible; + +• The component subtypes shall statically match; + +• If the component types are anonymous access types, then the accessibility level of the + +operand type shall not be statically deeper than that of the target type; + +• Neither the target type nor the operand type shall be limited; + +• If the target type of a view conversion has aliased components, then so shall the operand + +type; and + +24.1/2 + +24.2/2 + +24.3/2 + +24.4/2 + +24.5/2 + +24.6/2 + +24.7/2 + +24.8/2 + +• The operand type of a view conversion shall not have a tagged, private, or volatile + +24.9/2 + +subcomponent. + +• If the target type is universal_access, then the operand type shall be an access type. +• If the target type is a general access-to-object type, then the operand type shall be universal_- + +24.10/2 + +24.11/2 + +access or an access-to-object type. Further, if the operand type is not universal_access: + +• If the target type is an access-to-variable type, then the operand type shall be an access-to- + +24.12/2 + +variable type; + +• If the target designated type is tagged, then the operand designated type shall be convertible + +24.13/2 + +to the target designated type; + +• If the target designated type is not tagged, then the designated types shall be the same, and + +24.14/2 + +either: + +• + +• + +the designated subtypes shall statically match; or + +the designated type shall be discriminated in its full view and unconstrained in any +partial view, and one of the designated subtypes shall be unconstrained; + +• The accessibility level of the operand type shall not be statically deeper than that of the +target type, unless the target type is an anonymous access type of a stand-alone object. If +the target type is that of such a stand-alone object, the accessibility level of the operand +type shall not be statically deeper than that of the declaration of the stand-alone object. In + +24.15/2 + +24.16/2 + +24.17/3 + +125 13 December 2012 + +Type Conversions 4.6 + + Ada Reference Manual — 2012 Edition + +addition to the places where Legality Rules normally apply (see 12.3), this rule applies also +in the private part of an instance of a generic unit. + +24.18/2 + +• If the target type is a pool-specific access-to-object type, then the operand type shall be + +universal_access. + +24.19/2 + +24.20/3 + +24.21/2 + +25 + +26/3 + +• If the target type is an access-to-subprogram type, then the operand type shall be universal_- +access or an access-to-subprogram type. Further, if the operand type is not universal_access: + +• The designated profiles shall be subtype conformant. + +• The accessibility level of the operand type shall not be statically deeper than that of the +target type. In addition to the places where Legality Rules normally apply (see 12.3), this +rule applies also in the private part of an instance of a generic unit. If the operand type is +declared within a generic body, the target type shall be declared within the generic body. + +Static Semantics + +A type_conversion that is a value conversion denotes the value that is the result of converting the value of +the operand to the target subtype. + +A type_conversion that is a view conversion denotes a view of the object denoted by the operand. This +view is a variable of the target type if the operand denotes a variable; otherwise, it is a constant of the +target type. + +27 + +The nominal subtype of a type_conversion is its target subtype. + +28 + +29 + +30 + +31 + +32 + +33 + +34 + +35 + +36 + +37 + +Dynamic Semantics + +For the evaluation of a type_conversion that is a value conversion, the operand is evaluated, and then the +value of the operand is converted to a corresponding value of the target type, if any. If there is no value of +the target type that corresponds to the operand value, Constraint_Error is raised; this can only happen on +conversion to a modular type, and only when the operand value is outside the base range of the modular +type. Additional rules follow: + +• Numeric Type Conversion + +• If the target and the operand types are both integer types, then the result is the value of the + +target type that corresponds to the same mathematical integer as the operand. + +• If the target type is a decimal fixed point type, then the result is truncated (toward 0) if the + +value of the operand is not a multiple of the small of the target type. + +• If the target type is some other real type, then the result is within the accuracy of the target +type (see G.2, “Numeric Performance Requirements”, for implementations that support the +Numerics Annex). + +• If the target type is an integer type and the operand type is real, the result is rounded to the + +nearest integer (away from zero if exactly halfway between two integers). + +• Enumeration Type Conversion + +• The result is the value of the target type with the same position number as that of the + +operand value. + +• Array Type Conversion + +• If the target subtype is a constrained array subtype, then a check is made that the length of +each dimension of the value of the operand equals the length of the corresponding +dimension of the target subtype. The bounds of the result are those of the target subtype. + +4.6 Type Conversions + +13 December 2012 126 + + Ada Reference Manual — 2012 Edition + +• If the target subtype is an unconstrained array subtype, then the bounds of the result are +obtained by converting each bound of the value of the operand to the corresponding index +type of the target type. For each nonnull index range, a check is made that the bounds of the +range belong to the corresponding index subtype. + +38 + +• In either array case, the value of each component of the result is that of the matching + +39 + +component of the operand value (see 4.5.2). + +• If the component types of the array types are anonymous access types, then a check is made +that the accessibility level of the operand type is not deeper than that of the target type. + +39.1/2 + +• Composite (Non-Array) Type Conversion + +• The value of each nondiscriminant component of the result is that of the matching + +component of the operand value. + +• The tag of the result is that of the operand. If the operand type is class-wide, a check is +made that the tag of the operand identifies a (specific) type that is covered by or descended +from the target type. + +• For each discriminant of the target type that corresponds to a discriminant of the operand +type, its value is that of the corresponding discriminant of the operand value; if it +corresponds to more than one discriminant of the operand type, a check is made that all +these discriminants are equal in the operand value. + +• For each discriminant of the target type that corresponds to a discriminant that is specified +by the derived_type_definition for some ancestor of the operand type (or if class-wide, +some ancestor of the specific type identified by the tag of the operand), its value in the +result is that specified by the derived_type_definition. + +• For each discriminant of the operand type that corresponds to a discriminant that is +specified by the derived_type_definition for some ancestor of the target type, a check is +made that in the operand value it equals the value specified for it. + +• For each discriminant of the result, a check is made that its value belongs to its subtype. + +• Access Type Conversion + +• For an access-to-object type, a check is made that the accessibility level of the operand type +is not deeper than that of the target type, unless the target type is an anonymous access type +of a stand-alone object. If the target type is that of such a stand-alone object, a check is +made that the accessibility level of the operand type is not deeper than that of the +declaration of the stand-alone object; then if the check succeeds, the accessibility level of +the target type becomes that of the operand type. + +• If the operand value is null, the result of the conversion is the null value of the target type. + +• If the operand value is not null, then the result designates the same object (or subprogram) +as is designated by the operand value, but viewed as being of the target designated subtype +(or profile); any checks associated with evaluating a conversion to the target designated +subtype are performed. + +After conversion of the value to the target type, if the target subtype is constrained, a check is performed +that the value satisfies this constraint. If the target subtype excludes null, then a check is made that the +value is not null. If predicate checks are enabled for the target subtype (see 3.2.4), a check is performed +that the predicate of the target subtype is satisfied for the value. + +40 + +41 + +42 + +43 + +44 + +45 + +46 + +47 + +48/3 + +49/2 + +50 + +51/3 + +For the evaluation of a view conversion, the operand name is evaluated, and a new view of the object +denoted by the operand is created, whose type is the target type; if the target type is composite, checks are +performed as above for a value conversion. + +52 + +127 13 December 2012 + +Type Conversions 4.6 + + Ada Reference Manual — 2012 Edition + +53 + +The properties of this new view are as follows: + +54/1 + +55 + +56 + +57/3 + +• If the target type is composite, the bounds or discriminants (if any) of the view are as defined +above for a value conversion; each nondiscriminant component of the view denotes the matching +component of the operand object; the subtype of the view is constrained if either the target +subtype or the operand object is constrained, or if the target subtype is indefinite, or if the +operand type is a descendant of the target type and has discriminants that were not inherited +from the target type; + +• If the target type is tagged, then an assignment to the view assigns to the corresponding part of +the object denoted by the operand; otherwise, an assignment to the view assigns to the object, +after converting the assigned value to the subtype of the object (which might raise +Constraint_Error); + +• Reading the value of the view yields the result of converting the value of the operand object to +the target subtype (which might raise Constraint_Error), except if the object is of an access type +and the view conversion is passed as an out parameter; in this latter case, the value of the +operand object is used to initialize the formal parameter without checking against any constraint +of the target subtype (see 6.4.1). + +an Accessibility_Check + +fails, +If +Assertions.Assertion_Error is raised. Any other check associated with a conversion raises Constraint_Error +if it fails. + +fails, Program_Error + +a predicate + +raised. + +check + +is + +If + +58 + +Conversion to a type is the same as conversion to an unconstrained subtype of the type. + +59 + +60 + +61/2 + +62 + +63 + +64 + +65 + +66 + +67 + +68 + +NOTES +19 In addition to explicit type_conversions, type conversions are performed implicitly in situations where the expected +type and the actual type of a construct differ, as is permitted by the type resolution rules (see 8.6). For example, an integer +literal is of the type universal_integer, and is implicitly converted when assigned to a target of some specific integer type. +Similarly, an actual parameter of a specific tagged type is implicitly converted when the corresponding formal parameter +is of a class-wide type. + +Even when the expected and actual types are the same, implicit subtype conversions are performed to adjust the array +bounds (if any) of an operand to match the desired target subtype, or to raise Constraint_Error if the (possibly adjusted) +value does not satisfy the constraints of the target subtype. + +20 A ramification of the overload resolution rules is that the operand of an (explicit) type_conversion cannot be an +allocator, an aggregate, a string_literal, a character_literal, or an attribute_reference for an Access or Unchecked_Access +attribute. Similarly, such an expression enclosed by parentheses is not allowed. A qualified_expression (see 4.7) can be +used instead of such a type_conversion. + +21 The constraint of the target subtype has no effect for a type_conversion of an elementary type passed as an out +parameter. Hence, it is recommended that the first subtype be specified as the target to minimize confusion (a similar +recommendation applies to renaming and generic formal in out objects). + +Examples of numeric type conversion: + +Real(2*J) -- value is converted to floating point +Integer(1.6) -- value is 2 +Integer(-0.4) -- value is 0 + +Examples + +Example of conversion between derived types: +type A_Form is new B_Form; +X : A_Form; +Y : B_Form; + +X := A_Form(Y); +Y := B_Form(X); -- the reverse conversion + +4.6 Type Conversions + +13 December 2012 128 + + Ada Reference Manual — 2012 Edition + +Examples of conversions between array types: + +type Sequence is array (Integer range <>) of Integer; +subtype Dozen is Sequence(1 .. 12); +Ledger : array(1 .. 100) of Integer; +Sequence(Ledger) -- bounds are those of Ledger +Sequence(Ledger(31 .. 42)) -- bounds are 31 and 42 +Dozen(Ledger(31 .. 42)) -- bounds are those of Dozen + +4.7 Qualified Expressions + +A qualified_expression is used to state explicitly the type, and to verify the subtype, of an operand that is +either an expression or an aggregate. + +qualified_expression ::= + subtype_mark'(expression) | subtype_mark'aggregate + +Syntax + +Name Resolution Rules + +The operand (the expression or aggregate) shall resolve to be of the type determined by the subtype_- +mark, or a universal type that covers it. + +69 +70 + +71 + +1 + +2 + +3 + +If the operand of a qualified_expression denotes an object, the qualified_expression denotes a constant +view of that object. The nominal subtype of a qualified_expression is the subtype denoted by the +subtype_mark. + +3.1/3 + +Static Semantics + +Dynamic Semantics + +The evaluation of a qualified_expression evaluates the operand (and if of a universal type, converts it to +the type determined by the subtype_mark) and checks that its value belongs to the subtype denoted by the +subtype_mark. The exception Constraint_Error is raised if this check fails. + +NOTES +22 When a given context does not uniquely identify an expected type, a qualified_expression can be used to do so. In +particular, if an overloaded name or aggregate is passed to an overloaded subprogram, it might be necessary to qualify +the operand to resolve its type. + +Examples + +Examples of disambiguating expressions using qualification: +type Mask is (Fix, Dec, Exp, Signif); +type Code is (Fix, Cla, Dec, Tnz, Sub); +Print (Mask'(Dec)); -- Dec is of type Mask +Print (Code'(Dec)); -- Dec is of type Code +for J in Code'(Fix) .. Code'(Dec) loop ... -- qualification needed for either Fix or Dec +for J in Code range Fix .. Dec loop ... -- qualification unnecessary +for J in Code'(Fix) .. Dec loop ... -- qualification unnecessary for Dec +Dozen'(1 | 3 | 5 | 7 => 2, others => 0) -- see 4.6 + +4 + +5 + +6 + +7 + +8 + +9 + +10 + +4.8 Allocators + +The evaluation of an allocator creates an object and yields an access value that designates the object. + +1 + +129 13 December 2012 + +Type Conversions 4.6 + + 2/3 + +2.1/3 + +2.2/3 + +3/3 + +Ada Reference Manual — 2012 Edition + +Syntax + +allocator ::= + new [subpool_specification] subtype_indication + | new [subpool_specification] qualified_expression + +subpool_specification ::= (subpool_handle_name) + +For an allocator with a subtype_indication, the subtype_indication shall not specify a +null_exclusion. + +Name Resolution Rules + +The expected type for an allocator shall be a single access-to-object type with designated type D such that +either D covers the type determined by the subtype_mark of the subtype_indication or qualified_- +expression, or +is D'Class. A +is anonymous and +subpool_handle_name is expected to be of any type descended from Subpool_Handle, which is the type +used to identify a subpool, declared in package System.Storage_Pools.Subpools (see 13.11.4). + +the determined + +the expected + +type + +type + +Legality Rules + +4 + +An initialized allocator is an allocator with a qualified_expression. An uninitialized allocator is one with a +subtype_indication. In the subtype_indication of an uninitialized allocator, a constraint is permitted only +if the subtype_mark denotes an unconstrained composite subtype; if there is no constraint, then the +subtype_mark shall denote a definite subtype. + +5/2 + +If the type of the allocator is an access-to-constant type, the allocator shall be an initialized allocator. + +5.1/3 + +5.2/3 + +5.3/3 + +5.4/3 + +5.5/3 + +5.6/3 + +6/3 + +If a subpool_specification is given, the type of the storage pool of the access type shall be a descendant of +Root_Storage_Pool_With_Subpools. + +If the designated type of the type of the allocator is class-wide, the accessibility level of the type +determined by the subtype_indication or qualified_expression shall not be statically deeper than that of +the type of the allocator. + +If the subtype determined by the subtype_indication or qualified_expression of the allocator has one or +more access discriminants, then the accessibility level of the anonymous access type of each access +discriminant shall not be statically deeper than that of the type of the allocator (see 3.10.2). + +An allocator shall not be of an access type for which the Storage_Size has been specified by a static +expression with value zero or is defined by the language to be zero. + +If the designated type of the type of the allocator is limited, then the allocator shall not be used to define +the value of an access discriminant, unless the discriminated type is immutably limited (see 7.5). + +In addition to the places where Legality Rules normally apply (see 12.3), these rules apply also in the +private part of an instance of a generic unit. + +Static Semantics + +If the designated type of the type of the allocator is elementary, then the subtype of the created object is +the designated subtype. If the designated type is composite, then the subtype of the created object is the +designated subtype when the designated subtype is constrained or there is an ancestor of the designated +type that has a constrained partial view; otherwise, the created object is constrained by its initial value +(even if the designated subtype is unconstrained with defaults). + +4.8 Allocators + +13 December 2012 130 + + Ada Reference Manual — 2012 Edition + +Dynamic Semantics + +For the evaluation of an initialized allocator, the evaluation of the qualified_expression is performed first. +An object of the designated type is created and the value of the qualified_expression is converted to the +designated subtype and assigned to the object. + +For the evaluation of an uninitialized allocator, the elaboration of the subtype_indication is performed +first. Then: + +• If the designated type is elementary, an object of the designated subtype is created and any + +implicit initial value is assigned; + +• If the designated type is composite, an object of the designated type is created with tag, if any, +determined by the subtype_mark of the subtype_indication. This object is then initialized by +default (see 3.3.1) using the subtype_indication to determine its nominal subtype. A check is +made that the value of the object belongs to the designated subtype. Constraint_Error is raised if +this check fails. This check and the initialization of the object are performed in an arbitrary +order. + +For any allocator, if the designated type of the type of the allocator is class-wide, then a check is made +that the master of the type determined by the subtype_indication, or by the tag of the value of the +qualified_expression, includes the elaboration of the type of the allocator. If any part of the subtype +determined by the subtype_indication or qualified_expression of the allocator (or by the tag of the value +if the type of the qualified_expression is class-wide) has one or more access discriminants, then a check is +made that the accessibility level of the anonymous access type of each access discriminant is not deeper +than that of the type of the allocator. Program_Error is raised if either such check fails. + +7/2 + +8 + +9/2 + +10/2 + +10.1/3 + +If the object to be created by an allocator has a controlled or protected part, and the finalization of the +collection of the type of the allocator (see 7.6.1) has started, Program_Error is raised. + +10.2/2 + +If the object to be created by an allocator contains any tasks, and the master of the type of the allocator is +completed, and all of the dependent tasks of the master are terminated (see 9.3), then Program_Error is +raised. + +If the allocator includes a subpool_handle_name, Constraint_Error is raised if the subpool handle is null. +Program_Error is raised if the subpool does not belong (see 13.11.4) to the storage pool of the access type +of the allocator. + +10.3/2 + +10.4/3 + +If the created object contains any tasks, they are activated (see 9.2). Finally, an access value that +designates the created object is returned. + +11 + + It is a bounded error if the finalization of the collection of the type (see 7.6.1) of the allocator has started. +If the error is detected, Program_Error is raised. Otherwise, the allocation proceeds normally. + +11.1/2 + +Bounded (Run-Time) Errors + +NOTES +23 Allocators cannot create objects of an abstract type. See 3.9.3. + +24 If any part of the created object is controlled, the initialization includes calls on corresponding Initialize or Adjust +procedures. See 7.6. + +25 As explained in 13.11, “Storage Management”, the storage for an object allocated by an allocator comes from a +storage pool (possibly user defined). The exception Storage_Error is raised by an allocator if there is not enough storage. +Instances of Unchecked_Deallocation may be used to explicitly reclaim storage. + +26 Implementations are permitted, but not required, to provide garbage collection. + +12 + +13 + +14 + +15/3 + +131 13 December 2012 + +Allocators 4.8 + + Ada Reference Manual — 2012 Edition + +Examples of allocators: + +Examples + +new Cell'(0, null, null) -- initialized explicitly, see 3.10.1 +new Cell'(Value => 0, Succ => null, Pred => null) -- initialized explicitly +new Cell -- not initialized +new Matrix(1 .. 10, 1 .. 20) -- the bounds only are given +new Matrix'(1 .. 10 => (1 .. 20 => 0.0)) -- initialized explicitly +new Buffer(100) -- the discriminant only is given +new Buffer'(Size => 80, Pos => 0, Value => (1 .. 80 => 'A')) -- initialized explicitly +Expr_Ptr'(new Literal) -- allocator for access-to-class-wide type, see 3.9.1 +Expr_Ptr'(new Literal'(Expression with 3.5)) -- initialized explicitly + +4.9 Static Expressions and Static Subtypes + +Certain expressions of a scalar or string type are defined to be static. Similarly, certain discrete ranges are +defined to be static, and certain scalar and string subtypes are defined to be static subtypes. Static means +determinable at compile time, using the declared properties or values of the program entities. + +A static expression is a scalar or string expression that is one of the following: + +• a numeric_literal; +• a string_literal of a static string subtype; +• a name that denotes the declaration of a named number or a static constant; +• a function_call whose function_name or function_prefix statically denotes a static function, and +whose actual parameters, if any (whether given explicitly or by default), are all static +expressions; + +• an attribute_reference that denotes a scalar value, and whose prefix denotes a static scalar + +subtype; + +• an attribute_reference whose prefix statically denotes a statically constrained array object or +array subtype, and whose attribute_designator is First, Last, or Length, with an optional +dimension; + +• a type_conversion whose subtype_mark denotes a static scalar subtype, and whose operand is a + +static expression; + +16 + +17 + +18 + +19 + +20 + +1 + +2 + +3 + +4 + +5 + +6 + +7 + +8 + +9 + +10 + +• a qualified_expression whose subtype_mark denotes a static (scalar or string) subtype, and + +whose operand is a static expression; + +11/3 + +12 + +12.1/3 + +13 + +14 + +15 + +• a membership + +is a static expression, and whose +test whose simple_expression +membership_choice_list consists only of membership_choices +that are either static +choice_expressions, static ranges, or subtype_marks that denote a static (scalar or string) +subtype; + +• a short-circuit control form both of whose relations are static expressions; +• a + +conditional_expression + +of whose + +conditions, + +all + +selecting_expressions, + +and + +dependent_expressions are static expressions; + +• a static expression enclosed in parentheses. + +A name statically denotes an entity if it denotes the entity and: + +• It is a direct_name, expanded name, or character_literal, and it denotes a declaration other than + +a renaming_declaration; or + +4.8 Allocators + +13 December 2012 132 + + Ada Reference Manual — 2012 Edition + +• It is an attribute_reference whose prefix statically denotes some entity; or +• It denotes a renaming_declaration with a name that statically denotes the renamed entity. + +A static function is one of the following: + +• a predefined operator whose parameter and result types are all scalar types none of which are + +descendants of formal scalar types; + +• a predefined concatenation operator whose result type is a string type; +• an enumeration literal; +• a language-defined attribute that is a function, if the prefix denotes a static scalar subtype, and if + +the parameter and result types are scalar. + +In any case, a generic formal subprogram is not a static function. + +A static constant is a constant view declared by a full constant declaration or an object_renaming_- +declaration with a static nominal subtype, having a value defined by a static scalar expression or by a +static string expression whose value has a length not exceeding the maximum length of a string_literal in +the implementation. + +A static range is a range whose bounds are static expressions, or a range_attribute_reference that is +equivalent to such a range. A static discrete_range is one that is a static range or is a subtype_indication +that defines a static scalar subtype. The base range of a scalar type is a static range, unless the type is a +descendant of a formal scalar type. + +A static subtype is either a static scalar subtype or a static string subtype. A static scalar subtype is an +unconstrained scalar subtype whose type is not a descendant of a formal type, or a constrained scalar +subtype formed by imposing a compatible static constraint on a static scalar subtype. A static string +subtype is an unconstrained string subtype whose index subtype and component subtype are static, or a +constrained string subtype formed by imposing a compatible static constraint on a static string subtype. In +any case, the subtype of a generic formal object of mode in out, and the result subtype of a generic formal +function, are not static. Also, a subtype is not static if any Dynamic_Predicate specifications apply to it. + +The different kinds of static constraint are defined as follows: + +• A null constraint is always static; +• A scalar constraint is static if it has no range_constraint, or one with a static range; +• An index constraint is static if each discrete_range is static, and each index subtype of the + +corresponding array type is static; + +• A discriminant constraint is static if each expression of the constraint is static, and the subtype + +of each discriminant is static. + +In any case, the constraint of the first subtype of a scalar formal type is neither static nor null. + +A subtype is statically constrained if it is constrained, and its constraint is static. An object is statically +constrained if its nominal subtype is statically constrained, or if it is a static string constant. + +An expression is statically unevaluated if it is part of: + +Legality Rules + +• + +the right operand of a static short-circuit control form whose value is determined by its left +operand; or + +16 + +17 + +18 + +19 + +20 + +21 + +22 + +23 + +24 + +25 + +26/3 + +27 + +28 + +29 + +30 + +31 + +31.1/2 + +32 + +32.1/3 + +32.2/3 + +133 13 December 2012 + +Static Expressions and Static Subtypes 4.9 + + Ada Reference Manual — 2012 Edition + +32.3/3 + +• a dependent_expression of an if_expression whose associated condition is static and equals + +False; or + +32.4/3 + +32.5/3 + +32.6/3 + +• a condition or dependent_expression of an if_expression where the condition corresponding to +at least one preceding dependent_expression of the if_expression is static and equals True; or +• a dependent_expression of a case_expression whose selecting_expression is static and whose + +value is not covered by the corresponding discrete_choice_list; or + +• a choice_expression (or a simple_expression of a range that occurs as a membership_choice +of a membership_choice_list) of a static membership test that is preceded in the enclosing +membership_choice_list by another item whose individual membership test (see 4.5.2) +statically yields True. + +33/3 + +A static expression is evaluated at compile time except when it is statically unevaluated. The compile-time +evaluation of a static expression is performed exactly, without performing Overflow_Checks. For a static +expression that is evaluated: + +34/3 + +• The expression is illegal if its evaluation fails a language-defined check other than Overflow_- + +Check. For the purposes of this evaluation, the assertion policy is assumed to be Check. + +35/2 + +36/2 + +• If the expression is not part of a larger static expression and the expression is expected to be of a +single specific type, then its value shall be within the base range of its expected type. Otherwise, +the value may be arbitrarily large or small. + +• If the expression is of type universal_real and its expected type is a decimal fixed point type, +then its value shall be a multiple of the small of the decimal type. This restriction does not apply +if the expected type is a descendant of a formal scalar type (or a corresponding actual type in an +instance). + +37/2 + +In addition to the places where Legality Rules normally apply (see 12.3), the above restrictions also apply +in the private part of an instance of a generic unit. + +Implementation Requirements + +38/2 + +For a real static expression that is not part of a larger static expression, and whose expected type is not a +descendant of a formal type, the implementation shall round or truncate the value (according to the +Machine_Rounds attribute of the expected type) to the nearest machine number of the expected type; if the +value is exactly half-way between two machine numbers, the rounding performed is implementation- +defined. If the expected type is a descendant of a formal type, or if the static expression appears in the +body of an instance of a generic unit and the corresponding expression is nonstatic in the corresponding +generic body, then no special rounding or truncating is required — normal accuracy rules apply (see +Annex G). + +38.1/2 + +For a real static expression that is not part of a larger static expression, and whose expected type is not a +descendant of a formal type, the rounding should be the same as the default rounding for the target system. + +Implementation Advice + +39 + +40 + +41 + +42 + +NOTES +27 An expression can be static even if it occurs in a context where staticness is not required. + +28 A static (or run-time) type_conversion from a real type to an integer type performs rounding. If the operand value is +exactly half-way between two integers, the rounding is performed away from zero. + +Examples of static expressions: +1 + 1 -- 2 +abs(-10)*3 -- 30 + +Examples + +4.9 Static Expressions and Static Subtypes + +13 December 2012 134 + + Ada Reference Manual — 2012 Edition + +Kilo : constant := 1000; +Mega : constant := Kilo*Kilo; -- 1_000_000 +Long : constant := Float'Digits*2; +Half_Pi : constant := Pi/2; -- see 3.3.2 +Deg_To_Rad : constant := Half_Pi/90; +Rad_To_Deg : constant := 1.0/Deg_To_Rad; -- equivalent to 1.0/((3.14159_26536/2)/90) + +43 + +44 + +135 13 December 2012 + +Static Expressions and Static Subtypes 4.9 + + Ada Reference Manual — 2012 Edition + +4.9.1 Statically Matching Constraints and Subtypes + +1/2 + +A constraint statically matches another constraint if: + +Static Semantics + +1.1/2 + +1.2/2 + +1.3/2 + +1.4/2 + +2/3 + +3 + +4/3 + +5/3 + +6/3 + +7/3 + +8/3 + +9/3 + +10/3 + +• both are null constraints; +• both are static and have equal corresponding bounds or discriminant values; +• both are nonstatic and result from the same elaboration of a constraint of a subtype_indication + +or the same evaluation of a range of a discrete_subtype_definition; or +• both are nonstatic and come from the same formal_type_declaration. + +A subtype statically matches another subtype of the same type if they have statically matching constraints, +all predicate specifications that apply to them come from the same declarations, and, for access subtypes, +either both or neither exclude null. Two anonymous access-to-object subtypes statically match if their +designated subtypes statically match, and either both or neither exclude null, and either both or neither are +access-to-constant. Two anonymous access-to-subprogram subtypes statically match if their designated +profiles are subtype conformant, and either both or neither exclude null. + +Two ranges of the same type statically match if both result from the same evaluation of a range, or if both +are static and have equal corresponding bounds. + +A constraint is statically compatible with a scalar subtype if it statically matches the constraint of the +subtype, or if both are static and the constraint is compatible with the subtype. A constraint is statically +compatible with an access or composite subtype if it statically matches the constraint of the subtype, or if +the subtype is unconstrained. + +Two statically matching subtypes are statically compatible with each other. In addition, a subtype S1 is +statically compatible with a subtype S2 if: + +the constraint of S1 is statically compatible with S2, and + +if S2 excludes null, so does S1, and + +• +• +• either: + +• all predicate specifications that apply to S2 apply also to S1, or + +• both subtypes are static, every value that satisfies the predicate of S1 also satisfies the +predicate of S2, and it is not the case that both types each have at least one applicable +predicate specification, predicate checks are enabled (see 11.4.2) for S2, and predicate +checks are not enabled for S1. + +4.9.1 Statically Matching Constraints and Subtypes + +13 December 2012 136 + + Ada Reference Manual — 2012 Edition + +5 Statements + +A statement defines an action to be performed upon its execution. + +This clause describes the general rules applicable to all statements. Some statements are discussed in +later clauses: Procedure_call_statements and return statements are described in 6, “Subprograms”. +Entry_call_statements, requeue_statements, delay_statements, accept_statements, select_statements, +and abort_statements are described in 9, “Tasks and Synchronization”. Raise_statements are described +in 11, “Exceptions”, and code_statements in 13. The remaining forms of statements are presented in this +clause. + +1 + +2/3 + +5.1 Simple and Compound Statements - Sequences of Statements + +A statement is either simple or compound. A simple_statement encloses no other statement. A +compound_statement can enclose simple_statements and other compound_statements. + +1 + +sequence_of_statements ::= statement {statement} {label} + +statement ::= + {label} simple_statement | {label} compound_statement + +Syntax + +simple_statement ::= null_statement + | assignment_statement + | goto_statement + | simple_return_statement + | requeue_statement + | abort_statement + | code_statement + +compound_statement ::= + if_statement + | loop_statement + | extended_return_statement + | accept_statement + +null_statement ::= null; + +| exit_statement +| procedure_call_statement +| entry_call_statement +| delay_statement +| raise_statement + +| case_statement +| block_statement + +| select_statement + +label ::= <> + +statement_identifier ::= direct_name + +The direct_name of a statement_identifier shall be an identifier (not an operator_symbol). + +The direct_name of a statement_identifier shall resolve to denote its corresponding implicit declaration +(see below). + +Name Resolution Rules + +Distinct identifiers shall be used for all statement_identifiers that appear in the same body, including inner +block_statements but excluding inner program units. + +Legality Rules + +137 13 December 2012 + +Statements 5 + +2/3 + +3 + +4/2 + +5/2 + +6 + +7 + +8 + +9 + +10 + +11 + + Ada Reference Manual — 2012 Edition + +Static Semantics + +12 + +For each statement_identifier, there is an implicit declaration (with the specified identifier) at the end of +the declarative_part of the innermost block_statement or body that encloses the statement_identifier. The +implicit declarations occur in the same order as the statement_identifiers occur in the source text. If a +usage name denotes such an implicit declaration, the entity it denotes is the label, loop_statement, or +block_statement with the given statement_identifier. + +12.1/3 + +If one or more labels end a sequence_of_statements, an implicit null_statement follows the labels +before any following constructs. + +13 + +The execution of a null_statement has no effect. + +Dynamic Semantics + +14/2 + +A transfer of control is the run-time action of an exit_statement, return statement, goto_statement, or +requeue_statement, selection of a terminate_alternative, raising of an exception, or an abort, which +causes the next action performed to be one other than what would normally be expected from the other +rules of the language. As explained in 7.6.1, a transfer of control can cause the execution of constructs to +be completed and then left, which may trigger finalization. + +15 + +16 + +17 + +18 + +19 + +1 + +2 + +3 + +The execution of a sequence_of_statements consists of the execution of the individual statements in +succession until the sequence_ is completed. + +NOTES +1 A statement_identifier that appears immediately within the declarative region of a named loop_statement or an +accept_statement is nevertheless implicitly declared immediately within the declarative region of the innermost enclosing +body or block_statement; in other words, the expanded name for a named statement is not affected by whether the +statement occurs inside or outside a named loop or an accept_statement — only nesting within block_statements is +relevant to the form of its expanded name. + +Examples of labeled statements: + +<> <> <> <> null; +<> X := 1; + +Examples + +5.2 Assignment Statements + +An assignment_statement replaces the current value of a variable with the result of evaluating an +expression. + +assignment_statement ::= + variable_name := expression; + +Syntax + +The execution of an assignment_statement includes the evaluation of the expression and the assignment +of the value of the expression into the target. An assignment operation (as opposed to an assignment_- +statement) is performed in other contexts as well, including object initialization and by-copy parameter +passing. The target of an assignment operation is the view of the object to which a value is being assigned; +the target of an assignment_statement is the variable denoted by the variable_name. + +4/2 + +The variable_name of an assignment_statement is expected to be of any type. The expected type for the +expression is the type of the target. + +Name Resolution Rules + +5.1 Simple and Compound Statements - Sequences of Statements + +13 December 2012 138 + + Ada Reference Manual — 2012 Edition + +The target denoted by the variable_name shall be a variable of a nonlimited type. + +Legality Rules + +If the target is of a tagged class-wide type T'Class, then the expression shall either be dynamically tagged, +or of type T and tag-indeterminate (see 3.9.2). + +Dynamic Semantics + +For the execution of an assignment_statement, the variable_name and the expression are first evaluated +in an arbitrary order. + +When the type of the target is class-wide: + +• If the expression is tag-indeterminate (see 3.9.2), then the controlling tag value for the + +expression is the tag of the target; + +• Otherwise (the expression is dynamically tagged), a check is made that the tag of the value of +the expression is the same as that of the target; if this check fails, Constraint_Error is raised. + +The value of the expression is converted to the subtype of the target. The conversion might raise an +exception (see 4.6). + +In cases involving controlled types, the target is finalized, and an anonymous object might be used as an +intermediate in the assignment, as described in 7.6.1, “Completion and Finalization”. In any case, the +converted value of the expression is then assigned to the target, which consists of the following two steps: + +• The value of the target becomes the converted value. +• If any part of the target is controlled, its value is adjusted as explained in subclause 7.6. + +NOTES +2 The tag of an object never changes; in particular, an assignment_statement does not change the tag of the target. + +This paragraph was deleted. + +Examples + +Examples of assignment statements: +Value := Max_Value - 1; +Shade := Blue; +Next_Frame(F)(M, N) := 2.5; -- see 4.1.1 +U := Dot_Product(V, W); -- see 6.3 +Writer := (Status => Open, Unit => Printer, Line_Count => 60); -- see 3.8.1 +Next_Car.all := (72074, null); -- see 3.10.1 + +Examples involving scalar subtype conversions: + +I, J : Integer range 1 .. 10 := 5; +K : Integer range 1 .. 20 := 15; + ... +I := J; -- identical ranges +K := J; -- compatible ranges +J := K; -- will raise Constraint_Error if K > 10 + +5/2 + +6 + +7 + +8 + +9 + +10 + +11 + +12 + +13 + +14/3 + +15 + +16/2 + +17 + +18 + +19 + +20 + +21 + +22 + +23 + +139 13 December 2012 + +Assignment Statements 5.2 + + 24 +25 + +26 + +27 + +28 + +1 + +2 + +Ada Reference Manual — 2012 Edition + +Examples involving array subtype conversions: + +A : String(1 .. 31); +B : String(3 .. 33); + ... +A := B; -- same number of components +A(1 .. 9) := "tar sauce"; +A(4 .. 12) := A(1 .. 9); -- A(1 .. 12) = "tartar sauce" + +NOTES +3 Notes on the examples: Assignment_statements are allowed even in the case of overlapping slices of the same array, +because the variable_name and expression are both evaluated before copying the value into the variable. In the above +example, an implementation yielding A(1 .. 12) = "tartartartar" would be incorrect. + +5.3 If Statements + +An if_statement selects for execution at most one of the enclosed sequences_of_statements, depending +on the (truth) value of one or more corresponding conditions. + +Syntax + +if_statement ::= + if condition then + sequence_of_statements + {elsif condition then + sequence_of_statements} + [else + sequence_of_statements] + end if; + +Paragraphs 3 and 4 were deleted. + +5/3 + +For the execution of an if_statement, the condition specified after if, and any conditions specified after +elsif, are evaluated in succession (treating a final else as elsif True then), until one evaluates to True or all +conditions are evaluated and yield False. If a condition evaluates to True, then the corresponding +sequence_of_statements is executed; otherwise, none of them is executed. + +Dynamic Semantics + +6 + +7 + +8 + +9 + +Examples of if statements: + +Examples + +if Month = December and Day = 31 then + Month := January; + Day := 1; + Year := Year + 1; +end if; +if Line_Too_Short then + raise Layout_Error; +elsif Line_Full then + New_Line; + Put(Item); +else + Put(Item); +end if; +if My_Car.Owner.Vehicle /= My_Car then -- see 3.10.1 + Report ("Incorrect data"); +end if; + +5.2 Assignment Statements + +13 December 2012 140 + + Ada Reference Manual — 2012 Edition + +5.4 Case Statements + +A case_statement selects for execution one of a number of alternative sequences_of_statements; the +chosen alternative is defined by the value of an expression. + +1 + +Syntax + +case_statement ::= + case selecting_expression is + case_statement_alternative + {case_statement_alternative} + end case; + +case_statement_alternative ::= + when discrete_choice_list => + sequence_of_statements + +2/3 + +3 + +The selecting_expression is expected to be of any discrete type. The expected type for each +discrete_choice is the type of the selecting_expression. + +4/3 + +Name Resolution Rules + +ranges given as discrete_choices of a +The choice_expressions, subtype_indications, and +case_statement shall be static. A discrete_choice others, if present, shall appear alone and in the last +discrete_choice_list. + +Legality Rules + +The possible values of the selecting_expression shall be covered (see 3.8.1) as follows: + +• If the selecting_expression is a name (including a type_conversion, qualified_expression, or +function_call) having a static and constrained nominal subtype, then each non-others +discrete_choice shall cover only values in that subtype that satisfy its predicate (see 3.2.4), and +each value of that subtype that satisfies its predicate shall be covered by some discrete_choice +(either explicitly or by others). + +• If the type of the selecting_expression is root_integer, universal_integer, or a descendant of a + +formal scalar type, then the case_statement shall have an others discrete_choice. + +• Otherwise, each value of the base range of the type of the selecting_expression shall be covered + +(either explicitly or by others). + +Two distinct discrete_choices of a case_statement shall not cover the same value. + +For the execution of a case_statement the selecting_expression is first evaluated. + +Dynamic Semantics + +If the value of the selecting_expression is covered by the discrete_choice_list of some case_statement_- +alternative, then the sequence_of_statements of the _alternative is executed. + +Otherwise (the value is not covered by any discrete_choice_list, perhaps due to being outside the base +range), Constraint_Error is raised. + +NOTES +4 The execution of a case_statement chooses one and only one alternative. Qualification of the expression of a +case_statement by a static subtype can often be used to limit the number of choices that need be given explicitly. + +5/3 + +6/3 + +7/3 + +8/3 + +9/3 + +10 + +11/3 + +12/3 + +13 + +14 + +141 13 December 2012 + +Case Statements 5.4 + + 15 + +16 + +17 + +18 + +1 + +2 + +3/3 + +4 + +5 + +6 + +7 + +Ada Reference Manual — 2012 Edition + +Examples + +=> null; + +Examples of case statements: +case Sensor is + when Elevation => Record_Elevation(Sensor_Value); + when Azimuth +=> Record_Azimuth (Sensor_Value); + when Distance => Record_Distance (Sensor_Value); + when others +end case; +case Today is + when Mon + when Fri + when Tue .. Thu => Generate_Report(Today); + when Sat .. Sun => null; +end case; +case Bin_Number(Count) is + when 1 + when 2 + when 3 | 4 => + Empty_Bin(1); + Empty_Bin(2); + when others +end case; + +=> Compute_Initial_Balance; +=> Compute_Closing_Balance; + +=> Update_Bin(1); +=> Update_Bin(2); + +=> raise Error; + +5.5 Loop Statements + +A loop_statement includes a sequence_of_statements that is to be executed repeatedly, zero or more +times. + +Syntax + +loop_statement ::= + [loop_statement_identifier:] + [iteration_scheme] loop + sequence_of_statements + end loop [loop_identifier]; + +iteration_scheme ::= while condition + | for loop_parameter_specification + | for iterator_specification + +loop_parameter_specification ::= + defining_identifier in [reverse] discrete_subtype_definition + +If a loop_statement has a loop_statement_identifier, then the identifier shall be repeated after the +end loop; otherwise, there shall not be an identifier after the end loop. + +A loop_parameter_specification declares a loop parameter, which is an object whose subtype is that +defined by the discrete_subtype_definition. + +Static Semantics + +For the execution of a loop_statement, the sequence_of_statements is executed repeatedly, zero or more +times, until the loop_statement is complete. The loop_statement is complete when a transfer of control +occurs that transfers control out of the loop, or, in the case of an iteration_scheme, as specified below. + +Dynamic Semantics + +5.4 Case Statements + +13 December 2012 142 + + Ada Reference Manual — 2012 Edition + +For the execution of a loop_statement with a while iteration_scheme, the condition is evaluated before +each execution of the sequence_of_statements; if the value of the condition is True, the sequence_of_- +statements is executed; if False, the execution of the loop_statement is complete. + +For the execution of a loop_statement with the iteration_scheme being for loop_parameter_- +specification, the loop_parameter_specification is first elaborated. This elaboration creates the loop +parameter and elaborates the discrete_subtype_definition. If the discrete_subtype_definition defines a +subtype with a null range, the execution of the loop_statement is complete. Otherwise, the +sequence_of_statements is executed once for each value of the discrete subtype defined by the +discrete_subtype_definition that satisfies the predicate of the subtype (or until the loop is left as a +consequence of a transfer of control). Prior to each such iteration, the corresponding value of the discrete +subtype is assigned to the loop parameter. These values are assigned in increasing order unless the +reserved word reverse is present, in which case the values are assigned in decreasing order. + +8 + +9/3 + +For details about +iterator_specification, see 5.5.2. + +the execution of a + +loop_statement with + +the + +iteration_scheme being for + +9.1/3 + +NOTES +5 A loop parameter is a constant; it cannot be updated within the sequence_of_statements of the loop (see 3.3). + +6 An object_declaration should not be given for a loop parameter, since the loop parameter is automatically declared by +the loop_parameter_specification. The scope of a loop parameter extends from the loop_parameter_specification to the +end of the loop_statement, and the visibility rules are such that a loop parameter is only visible within the +sequence_of_statements of the loop. + +7 The discrete_subtype_definition of a for loop is elaborated just once. Use of the reserved word reverse does not alter +the discrete subtype defined, so that the following iteration_schemes are not equivalent; the first has a null range. + +for J in reverse 1 .. 0 +for J in 0 .. 1 + +Examples + +Example of a loop statement without an iteration scheme: + +loop + Get(Current_Character); + exit when Current_Character = '*'; +end loop; + +Example of a loop statement with a while iteration scheme: +while Bid(N).Price < Cut_Off.Price loop + Record_Bid(Bid(N).Price); + N := N + 1; +end loop; + +Example of a loop statement with a for iteration scheme: + +for J in Buffer'Range loop -- works even with a null range + if Buffer(J) /= Space then + Put(Buffer(J)); + end if; +end loop; + +Example of a loop statement with a name: + +Summation: + while Next /= Head loop -- see 3.10.1 + Sum := Sum + Next.Value; + Next := Next.Succ; + end loop Summation; + +10 + +11 + +12 + +13 + +14 + +15 + +16 + +17 + +18 + +19 + +20 + +21 + +143 13 December 2012 + +Loop Statements 5.5 + + Ada Reference Manual — 2012 Edition + +5.5.1 User-Defined Iterator Types + +The following language-defined generic library package exists: + +Static Semantics + +generic + type Cursor; + with function Has_Element (Position : Cursor) return Boolean; +package Ada.Iterator_Interfaces is + pragma Pure (Iterator_Interfaces); + type Forward_Iterator is limited interface; + function First (Object : Forward_Iterator) return Cursor is abstract; + function Next (Object : Forward_Iterator; Position : Cursor) + return Cursor is abstract; + type Reversible_Iterator is limited interface and Forward_Iterator; + function Last (Object : Reversible_Iterator) return Cursor is abstract; + function Previous (Object : Reversible_Iterator; Position : Cursor) + return Cursor is abstract; +end Ada.Iterator_Interfaces; + +An iterator type is a type descended from the Forward_Iterator interface from some instance of +Ada.Iterator_Interfaces. A reversible iterator type is a type descended from the Reversible_Iterator +interface from some instance of Ada.Iterator_Interfaces. An iterator object is an object of an iterator type. +A reversible iterator object is an object of a reversible iterator type. The formal subtype Cursor from the +associated instance of Ada.Iterator_Interfaces is the iteration cursor subtype for the iterator type. + +1/3 + +2/3 + +3/3 + +4/3 + +5/3 + +6/3 + +7/3 + +The following type-related operational aspects may be specified for an indexable container type T (see +4.1.6): + +8/3 + +Default_Iterator + +This aspect is specified by a name that denotes exactly one function declared immediately +within the same declaration list in which T is declared, whose first parameter is of type T or +T'Class or an access parameter whose designated type is type T or T'Class, whose other +parameters, if any, have default expressions, and whose result type is an iterator type. This +function is the default iterator function for T. Its result subtype is the default iterator +subtype for T. The iteration cursor subtype for the default iterator subtype is the default +cursor subtype for T. + +9/3 + +Iterator_Element + +This aspect is specified by a name that denotes a subtype. This is the default element +subtype for T. + +10/3 + +These aspects are inherited by descendants of type T (including T'Class). + +11/3 + +An iterable container type is an indexable container type with specified Default_Iterator and +Iterator_Element aspects. A reversible iterable container type is an iterable container type with the default +iterator type being a reversible iterator type. An iterable container object is an object of an iterable +container type. A reversible iterable container object is an object of a reversible iterable container type. + +Legality Rules + +12/3 + +The Constant_Indexing aspect (if any) of an iterable container type T shall denote exactly one function +with the following properties: + +13/3 + +• + +the result type of the function is covered by the default element type of T or is a reference type +(see 4.1.5) with an access discriminant designating a type covered by the default element type of +T; + +5.5.1 User-Defined Iterator Types + +13 December 2012 144 + + + + Ada Reference Manual — 2012 Edition + +• +• + +the type of the second parameter of the function covers the default cursor type for T; + +if there are more than two parameters, the additional parameters all have default expressions. + +This function (if any) is the default constant indexing function for T. + +The Variable_Indexing aspect (if any) of an iterable container type T shall denote exactly one function +with the following properties: + +• + +• +• + +the result type of the function is a reference type (see 4.1.5) with an access discriminant +designating a type covered by the default element type of T; + +the type of the second parameter of the function covers the default cursor type for T; + +if there are more than two parameters, the additional parameters all have default expressions. + +This function (if any) is the default variable indexing function for T. + +5.5.2 Generalized Loop Iteration + +Generalized forms of loop iteration are provided by an iterator_specification. + +iterator_specification ::= + defining_identifier in [reverse] iterator_name + | defining_identifier [: subtype_indication] of [reverse] iterable_name + +Syntax + +Name Resolution Rules + +For the first form of iterator_specification, called a generalized iterator, the expected type for the +iterator_name is any iterator type. For the second form of iterator_specification, the expected type for the +iterable_name is any array or iterable container type. If the iterable_name denotes an array object, the +iterator_specification is called an array component iterator; otherwise it is called a container element +iterator. + +Legality Rules + +If the reserved word reverse appears, the iterator_specification is a reverse iterator; otherwise it is a +forward iterator. In a reverse generalized iterator, the iterator_name shall be of a reversible iterator type. +In a reverse container element iterator, the default iterator type for the type of the iterable_name shall be a +reversible iterator type. + +The type of the subtype_indication, if any, of an array component iterator shall cover the component type +of the type of the iterable_name. The type of the subtype_indication, if any, of a container element +iterator shall cover the default element type for the type of the iterable_name. + +In a container element iterator whose iterable_name has type T, if the iterable_name denotes a constant +or the Variable_Indexing aspect is not specified for T, then the Constant_Indexing aspect shall be specified +for T. + +Static Semantics + +An iterator_specification declares a loop parameter. In a generalized iterator, the nominal subtype of the +loop parameter is the iteration cursor subtype. In an array component iterator or a container element +iterator, if a subtype_indication is present, it determines the nominal subtype of the loop parameter. In an +array component iterator, if a subtype_indication is not present, the nominal subtype of the loop parameter +is the component subtype of the type of the iterable_name. In a container element iterator, if a + +145 13 December 2012 + +User-Defined Iterator Types 5.5.1 + +14/3 + +15/3 + +16/3 + +17/3 + +18/3 + +19/3 + +20/3 + +21/3 + +1/3 + +2/3 + +3/3 + +4/3 + +5/3 + +6/3 + +7/3 + + 8/3 + +9/3 + +10/3 + +11/3 + +12/3 + +13/3 + +Ada Reference Manual — 2012 Edition + +subtype_indication is not present, the nominal subtype of the loop parameter is the default element +subtype for the type of the iterable_name. + +In a generalized iterator, the loop parameter is a constant. In an array component iterator, the loop +parameter is a constant if the iterable_name denotes a constant; otherwise it denotes a variable. In a +container element iterator, the loop parameter is a constant if the iterable_name denotes a constant, or if +the Variable_Indexing aspect is not specified for the type of the iterable_name; otherwise it is a variable. + +Dynamic Semantics + +For the execution of a loop_statement with an iterator_specification, the iterator_specification is first +elaborated. This elaboration elaborates the subtype_indication, if any. + +For a generalized iterator, the loop parameter is created, the iterator_name is evaluated, and the denoted +iterator object becomes the loop iterator. In a forward generalized iterator, the operation First of the +iterator type is called on the loop iterator, to produce the initial value for the loop parameter. If the result +of calling Has_Element on the initial value is False, then the execution of the loop_statement is complete. +Otherwise, the sequence_of_statements is executed and then the Next operation of the iterator type is +called with the loop iterator and the current value of the loop parameter to produce the next value to be +assigned to the loop parameter. This repeats until the result of calling Has_Element on the loop parameter +is False, or the loop is left as a consequence of a transfer of control. For a reverse generalized iterator, the +operations Last and Previous are called rather than First and Next. + +For an array component iterator, the iterable_name is evaluated and the denoted array object becomes the +array for the loop. If the array for the loop is a null array, then the execution of the loop_statement is +complete. Otherwise, the sequence_of_statements is executed with the loop parameter denoting each +component of the array for the loop, using a canonical order of components, which is last dimension +varying fastest (unless the array has convention Fortran, in which case it is first dimension varying fastest). +For a forward array component iterator, the iteration starts with the component whose index values are +each the first in their index range, and continues in the canonical order. For a reverse array component +iterator, the iteration starts with the component whose index values are each the last in their index range, +and continues +the reverse of the canonical order. The loop iteration proceeds until the +sequence_of_statements has been executed for each component of the array for the loop, or until the +loop is left as a consequence of a transfer of control. + +in + +For a container element iterator, the iterable_name is evaluated and the denoted iterable container object +becomes the iterable container object for the loop. The default iterator function for the type of the iterable +container object for the loop is called on the iterable container object and the result is the loop iterator. An +object of the default cursor subtype is created (the loop cursor). + +the + +then + +is False, + +loop_statement + +the execution of + +For a forward container element iterator, the operation First of the iterator type is called on the loop +iterator, to produce the initial value for the loop cursor. If the result of calling Has_Element on the initial +the +value +sequence_of_statements is executed with the loop parameter denoting an indexing (see 4.1.6) into the +iterable container object for the loop, with the only parameter to the indexing being the current value of +the loop cursor; then the Next operation of the iterator type is called with the loop iterator and the loop +cursor to produce the next value to be assigned to the loop cursor. This repeats until the result of calling +Has_Element on the loop cursor is False, or until the loop is left as a consequence of a transfer of control. +For a reverse container element iterator, the operations Last and Previous are called rather than First and +Next. If the loop parameter is a constant (see above), then the indexing uses the default constant indexing +function for the type of the iterable container object for the loop; otherwise it uses the default variable +indexing function. + +is complete. Otherwise, + +5.5.2 Generalized Loop Iteration + +13 December 2012 146 + + Ada Reference Manual — 2012 Edition + +Examples + +-- Array component iterator example: +for Element of Board loop -- See 3.6.1. + Element := Element * 2.0; -- Double each element of Board, a two-dimensional array. +end loop; + +14/3 + +For examples of use of generalized iterators, see A.18.32 and the corresponding container packages in +A.18.2 and A.18.3. + +15/3 + +5.6 Block Statements + +A block_statement encloses a handled_sequence_of_statements optionally preceded by a +declarative_part. + +Syntax + +block_statement ::= + [block_statement_identifier:] + [declare + declarative_part] + begin + handled_sequence_of_statements + end [block_identifier]; + +If a block_statement has a block_statement_identifier, then the identifier shall be repeated after the +end; otherwise, there shall not be an identifier after the end. + +A block_statement that has no explicit declarative_part has an implicit empty declarative_part. + +Static Semantics + +The execution of a block_statement consists of the elaboration of its declarative_part followed by the +execution of its handled_sequence_of_statements. + +Dynamic Semantics + +Examples + +Example of a block statement with a local variable: + +Swap: + declare + Temp : Integer; + begin + Temp := V; V := U; U := Temp; + end Swap; + +5.7 Exit Statements + +An exit_statement is used to complete the execution of an enclosing loop_statement; the completion is +conditional if the exit_statement includes a condition. + +exit_statement ::= + exit [loop_name] [when condition]; + +Syntax + +Name Resolution Rules + +The loop_name, if any, in an exit_statement shall resolve to denote a loop_statement. + +147 13 December 2012 + +Generalized Loop Iteration 5.5.2 + +1 + +2 + +3 + +4 + +5 + +6 + +7 + +1 + +2 + +3 + + 4 + +5 + +6 + +7 + +8 + +9 + +1 + +2 + +3 + +4 + +5 + +6 + +Ada Reference Manual — 2012 Edition + +Legality Rules + +Each exit_statement applies to a loop_statement; this is the loop_statement being exited. An exit_- +statement with a name is only allowed within the loop_statement denoted by the name, and applies to +that loop_statement. An exit_statement without a name is only allowed within a loop_statement, and +applies to the innermost enclosing one. An exit_statement that applies to a given loop_statement shall not +appear within a body or accept_statement, if this construct is itself enclosed by the given +loop_statement. + +For the execution of an exit_statement, the condition, if present, is first evaluated. If the value of the +condition is True, or if there is no condition, a transfer of control is done to complete the loop_statement. +If the value of the condition is False, no transfer of control takes place. + +Dynamic Semantics + +NOTES +8 Several nested loops can be exited by an exit_statement that names the outer loop. + +Examples of loops with exit statements: + +Examples + +for N in 1 .. Max_Num_Items loop + Get_New_Item(New_Item); + Merge_Item(New_Item, Storage_File); + exit when New_Item = Terminal_Item; +end loop; +Main_Cycle: + loop + -- initial statements + exit Main_Cycle when Found; + -- final statements + end loop Main_Cycle; + +5.8 Goto Statements + +A goto_statement specifies an explicit transfer of control from this statement to a target statement with a +given label. + +goto_statement ::= goto label_name; + +Syntax + +Name Resolution Rules + +The label_name shall resolve to denote a label; the statement with that label is the target statement. + +The innermost sequence_of_statements that encloses the target statement shall also enclose the +goto_statement. Furthermore, if a goto_statement is enclosed by an accept_statement or a body, then +the target statement shall not be outside this enclosing construct. + +Legality Rules + +Dynamic Semantics + +The execution of a goto_statement transfers control to the target statement, completing the execution of +any compound_statement that encloses the goto_statement but does not enclose the target. + +NOTES +9 The above rules allow transfer of control to a statement of an enclosing sequence_of_statements but not the reverse. +Similarly, they prohibit transfers of control such as between alternatives of a case_statement, if_statement, or + +5.7 Exit Statements + +13 December 2012 148 + + select_statement; between exception_handlers; or from an exception_handler of a handled_sequence_of_statements +back to its sequence_of_statements. + +Ada Reference Manual — 2012 Edition + +Examples + +Example of a loop containing a goto statement: + +<> +for I in 1 .. N-1 loop + if A(I) > A(I+1) then + Exchange(A(I), A(I+1)); + goto Sort; + end if; +end loop; + +7 + +8 + +149 13 December 2012 + +Goto Statements 5.8 + + Ada Reference Manual — 2012 Edition + +6 Subprograms + +A subprogram is a program unit or intrinsic operation whose execution is invoked by a subprogram call. +There are two forms of subprogram: procedures and functions. A procedure call is a statement; a function +call is an expression and returns a value. The definition of a subprogram can be given in two parts: a +subprogram declaration defining its interface, and a subprogram_body defining its execution. Operators +and enumeration literals are functions. + +1 + +A callable entity is a subprogram or entry (see Section 9). A callable entity is invoked by a call; that is, a +subprogram call or entry call. A callable construct is a construct that defines the action of a call upon a +callable entity: a subprogram_body, entry_body, or accept_statement. + +2/3 + +6.1 Subprogram Declarations + +A subprogram_declaration declares a procedure or function. + +Syntax + +subprogram_declaration ::= + [overriding_indicator] + subprogram_specification + [aspect_specification]; + +This paragraph was deleted. + +subprogram_specification ::= + procedure_specification + | function_specification + +procedure_specification ::= procedure defining_program_unit_name parameter_profile + +function_specification ::= function defining_designator parameter_and_result_profile + +designator ::= [parent_unit_name . ]identifier | operator_symbol + +defining_designator ::= defining_program_unit_name | defining_operator_symbol + +defining_program_unit_name ::= [parent_unit_name . ]defining_identifier + +The optional parent_unit_name is only allowed for library units (see 10.1.1). + +operator_symbol ::= string_literal + +The sequence of characters in an operator_symbol shall form a reserved word, a delimiter, or +compound delimiter that corresponds to an operator belonging to one of the six categories of +operators defined in subclause 4.5. + +defining_operator_symbol ::= operator_symbol + +parameter_profile ::= [formal_part] + +parameter_and_result_profile ::= + [formal_part] return [null_exclusion] subtype_mark + | [formal_part] return access_definition + +formal_part ::= + (parameter_specification {; parameter_specification}) + +parameter_specification ::= + defining_identifier_list : [aliased] mode [null_exclusion] subtype_mark [:= default_expression] + | defining_identifier_list : access_definition [:= default_expression] + +151 13 December 2012 + +Subprograms 6 + +1 + +2/3 + +3/2 + +4/2 + +4.1/2 + +4.2/2 + +5 + +6 + +7 + +8 + +9 + +10/3 + +11 + +12 + +13/2 + +14 + +15/3 + + 16 + +17 + +Ada Reference Manual — 2012 Edition + +mode ::= [in] | in out | out + +A formal parameter is an object directly visible within a subprogram_body that represents the actual +parameter passed to the subprogram in a call; it is declared by a parameter_specification. For a formal +parameter, the expected type for its default_expression, if any, is that of the formal parameter. + +Name Resolution Rules + +18/3 + +The parameter mode of a formal parameter conveys the direction of information transfer with the actual +parameter: in, in out, or out. Mode in is the default, and is the mode of a parameter defined by an +access_definition. + +19 + +A default_expression is only allowed in a parameter_specification for a formal parameter of mode in. + +Legality Rules + +20/3 + +21 + +22 + +23/2 + +A subprogram_declaration or a generic_subprogram_declaration requires a completion unless the +Import aspect (see B.1) is True for the declaration; the completion shall be a body or a +renaming_declaration (see 8.5). A completion is not allowed for an abstract_subprogram_declaration +(see 3.9.3), a null_procedure_declaration (see 6.7), or an expression_function_declaration (see 6.8). + +A name that denotes a formal parameter is not allowed within the formal_part in which it is declared, nor +within the formal_part of a corresponding body or accept_statement. + +Static Semantics + +The profile of (a view of) a callable entity is either a parameter_profile or parameter_and_result_profile; +it embodies information about the interface to that entity — for example, the profile includes information +about parameters passed to the callable entity. All callable entities have a profile — enumeration literals, +other subprograms, and entries. An access-to-subprogram type has a designated profile. Associated with a +profile is a calling convention. A subprogram_declaration declares a procedure or a function, as indicated +by the initial reserved word, with name and profile as given by its specification. + +The nominal subtype of a formal parameter is the subtype determined by the optional null_exclusion and +the subtype_mark, or defined by the access_definition, in the parameter_specification. The nominal +subtype of a function result is the subtype determined by the optional null_exclusion and the +subtype_mark, or defined by the access_definition, in the parameter_and_result_profile. + +23.1/3 + +An explicitly aliased parameter is a formal parameter whose parameter_specification includes the +reserved word aliased. + +24/2 + +25 + +26 + +27/2 + +An access parameter is a formal in parameter specified by an access_definition. An access result type is a +function result type specified by an access_definition. An access parameter or result type is of an +anonymous access type (see 3.10). Access parameters of an access-to-object type allow dispatching calls +to be controlled by access values. Access parameters of an access-to-subprogram type permit calls to +subprograms passed as parameters irrespective of their accessibility level. + +The subtypes of a profile are: + +• For any non-access parameters, the nominal subtype of the parameter. +• For any access parameters of an access-to-object type, the designated subtype of the parameter + +type. + +27.1/3 + +• For any access parameters of an access-to-subprogram type, the subtypes of the designated + +profile of the parameter type. + +28/2 + +• For any non-access result, the nominal subtype of the function result. + +6.1 Subprogram Declarations + +13 December 2012 152 + + Ada Reference Manual — 2012 Edition + +• For any access result type of an access-to-object type, the designated subtype of the result type. +• For any access result type of an access-to-subprogram type, the subtypes of the designated + +profile of the result type. + +The types of a profile are the types of those subtypes. + +A subprogram declared by an abstract_subprogram_declaration is abstract; a subprogram declared by a +subprogram_declaration is not. See 3.9.3, “Abstract Types and Subprograms”. Similarly, a procedure +is a null procedure; a procedure declared by a +declared by a null_procedure_declaration +subprogram_declaration is not. See 6.7, “Null Procedures”. Finally, a function declared by an +expression_function_declaration +a +expression +subprogram_declaration is not. See 6.8, “Expression Functions”. + +declared by + +function; + +function + +an + +is + +a + +28.1/2 + +28.2/3 + +29 + +30/3 + +An overriding_indicator is used to indicate whether overriding is intended. See 8.3.1, “Overriding +Indicators”. + +30.1/2 + +The elaboration of a subprogram_declaration has no effect. + +Dynamic Semantics + +NOTES +1 A parameter_specification with several identifiers is equivalent to a sequence of single parameter_specifications, as +explained in 3.3. + +2 Abstract subprograms do not have bodies, and cannot be used in a nondispatching call (see 3.9.3, “Abstract Types and +Subprograms”). + +3 The evaluation of default_expressions is caused by certain calls, as described in 6.4.1. They are not evaluated during +the elaboration of the subprogram declaration. + +4 Subprograms can be called recursively and can be called concurrently from multiple tasks. + +Examples of subprogram declarations: + +Examples + +procedure Traverse_Tree; +procedure Increment(X : in out Integer); +procedure Right_Indent(Margin : out Line_Size); -- see 3.5.4 +procedure Switch(From, To : in out Link); -- see 3.10.1 +function Random return Probability; -- see 3.5.7 +function Min_Cell(X : Link) return Cell; -- see 3.10.1 +function Next_Frame(K : Positive) return Frame; -- see 3.10 +function Dot_Product(Left, Right : Vector) return Real; -- see 3.6 +function "*"(Left, Right : Matrix) return Matrix; -- see 3.6 + +Examples of in parameters with default expressions: + +procedure Print_Header(Pages : in Natural; + Header : in Line := (1 .. Line'Last => ' '); -- see 3.6 + Center : in Boolean := True); + +31/2 + +32 + +33 + +34 + +35 + +36 + +37 + +38 + +39 + +40 + +41 + +42 + +153 13 December 2012 + +Subprogram Declarations 6.1 + + Ada Reference Manual — 2012 Edition + +6.1.1 Preconditions and Postconditions + +1/3 + +For a subprogram or entry, the following language-defined aspects may be specified with an +aspect_specification (see 13.1.1): + +2/3 + +Pre + +3/3 + +Pre'Class + +4/3 + +Post + +5/3 + +Post'Class + +This aspect specifies a specific precondition for a callable entity; it shall be specified by an +expression, called a specific precondition expression. If not specified for an entity, the +specific precondition expression for the entity is the enumeration literal True. + +This aspect specifies a class-wide precondition for an operation of a tagged type and its +descendants; it shall be specified by an expression, called a class-wide precondition +expression. If not specified for an entity, then if no other class-wide precondition applies to +the entity, the class-wide precondition expression for the entity is the enumeration literal +True. + +This aspect specifies a specific postcondition for a callable entity; it shall be specified by an +expression, called a specific postcondition expression. If not specified for an entity, the +specific postcondition expression for the entity is the enumeration literal True. + +This aspect specifies a class-wide postcondition for an operation of a tagged type and its +descendants; it shall be specified by an expression, called a class-wide postcondition +expression. If not specified for an entity, the class-wide postcondition expression for the +entity is the enumeration literal True. + +6/3 + +7/3 + +8/3 + +9/3 + +10/3 + +11/3 + +12/3 + +13/3 + +14/3 + +15/3 + +16/3 + +The expected type for a precondition or postcondition expression is any boolean type. + +Name Resolution Rules + +Within the expression for a Pre'Class or Post'Class aspect for a primitive subprogram of a tagged type T, a +name that denotes a formal parameter of type T is interpreted as having type T'Class. Similarly, a name +that denotes a formal access parameter of type access-to-T is interpreted as having type access-to-T'Class. +This ensures that the expression is well-defined for a primitive subprogram of a type descended from T. + +For an attribute_reference with attribute_designator Old, if the attribute reference has an expected type or +shall resolve to a given type, the same applies to the prefix; otherwise, the prefix shall be resolved +independently of context. + +Legality Rules + +The Pre or Post aspect shall not be specified for an abstract subprogram or a null procedure. Only the +Pre'Class and Post'Class aspects may be specified for such a subprogram. + +If a type T has an implicitly declared subprogram P inherited from a parent type T1 and a homograph (see +8.3) of P from a progenitor type T2, and + +• +• +• + +the corresponding primitive subprogram P1 of type T1 is neither null nor abstract; and + +the class-wide precondition expression True does not apply to P1 (implicitly or explicitly); and + +there is a class-wide precondition expression that applies to the corresponding primitive +subprogram P2 of T2 that does not fully conform to any class-wide precondition expression that +applies to P1, + +then: + +• If the type T is abstract, the implicitly declared subprogram P is abstract. +• Otherwise, the subprogram P requires overriding and shall be overridden with a nonabstract + +subprogram. + +6.1.1 Preconditions and Postconditions + +13 December 2012 154 + + Ada Reference Manual — 2012 Edition + +If a renaming of a subprogram or entry S1 overrides an inherited subprogram S2, then the overriding is +illegal unless each class-wide precondition expression that applies to S1 fully conforms to some class-wide +precondition expression that applies to S2 and each class-wide precondition expression that applies to S2 +fully conforms to some class-wide precondition expression that applies to S1. + +Static Semantics + +If a Pre'Class or Post'Class aspect is specified for a primitive subprogram of a tagged type T, then the +associated expression also applies to the corresponding primitive subprogram of each descendant of T. + +If performing checks is required by the Pre, Pre'Class, Post, or Post'Class assertion policies (see 11.4.2) in +effect at the point of a corresponding aspect specification applicable to a given subprogram or entry, then +the respective precondition or postcondition expressions are considered enabled. + +An expression is potentially unevaluated if it occurs within: + +• any part of an if_expression other than the first condition; +• a dependent_expression of a case_expression; +• +• a membership_choice other than the first of a membership operation. + +the right operand of a short-circuit control form; or + +For a prefix X that denotes an object of a nonlimited type, the following attribute is defined: + +X'Old + +For each X'Old in a postcondition expression that is enabled, a constant is implicitly +declared at the beginning of the subprogram or entry. The constant is of the type of X and is +initialized to the result of evaluating X (as an expression) at the point of the constant +declaration. The value of X'Old in the postcondition expression is the value of this constant; +the type of X'Old is the type of X. These implicit constant declarations occur in an arbitrary +order. + +Reference to this attribute is only allowed within a postcondition expression. The prefix of +an Old attribute_reference shall not contain a Result attribute_reference, nor an Old +attribute_reference, nor a use of an entity declared within the postcondition expression but +not within prefix +loop parameter of an enclosing +quantified_expression). The prefix of an Old attribute_reference that is potentially +unevaluated shall statically denote an entity. + +(for example, + +itself + +the + +For a prefix F that denotes a function declaration, the following attribute is defined: + +F'Result + +Within a postcondition expression for function F, denotes the result object of the function. +The type of this attribute is that of the function result except within a Post'Class +postcondition expression for a function with a controlling result or with a controlling access +result. For a controlling result, the type of the attribute is T'Class, where T is the function +result type. For a controlling access result, the type of the attribute is an anonymous access +type whose designated type is T'Class, where T is the designated type of the function result +type. + +Use of this attribute is allowed only within a postcondition expression for F. + +Dynamic Semantics + +Upon a call of the subprogram or entry, after evaluating any actual parameters, precondition checks are +performed as follows: + +• The specific precondition check begins with the evaluation of the specific precondition +expression that applies to the subprogram or entry, if it is enabled; if the expression evaluates to +False, Assertions.Assertion_Error is raised; if the expression is not enabled, the check succeeds. + +155 13 December 2012 + +Preconditions and Postconditions 6.1.1 + +17/3 + +18/3 + +19/3 + +20/3 + +21/3 + +22/3 + +23/3 + +24/3 + +25/3 + +26/3 + +27/3 + +28/3 + +29/3 + +30/3 + +31/3 + +32/3 + + + + Ada Reference Manual — 2012 Edition + +33/3 + +34/3 + +35/3 + +36/3 + +37/3 + +38/3 + +39/3 + +40/3 + +• The class-wide precondition check begins with the evaluation of any enabled class-wide +precondition expressions that apply to the subprogram or entry. If and only if all the class-wide +precondition expressions evaluate to False, Assertions.Assertion_Error is raised. + +The precondition checks are performed in an arbitrary order, and if any of the class-wide precondition +expressions evaluate to True, it is not specified whether the other class-wide precondition expressions are +evaluated. The precondition checks and any check for elaboration of the subprogram body are performed +in an arbitrary order. It is not specified whether in a call on a protected operation, the checks are +performed before or after starting the protected action. For an entry call, the checks are performed prior to +checking whether the entry is open. + +Upon successful return from a call of the subprogram or entry, prior to copying back any by-copy in out +or out parameters, the postcondition check is performed. This consists of the evaluation of any enabled +specific and class-wide postcondition expressions that apply to the subprogram or entry. If any of the +postcondition expressions evaluate to False, then Assertions.Assertion_Error is raised. The postcondition +expressions are evaluated in an arbitrary order, and if any postcondition expression evaluates to False, it is +not specified whether any other postcondition expressions are evaluated. The postcondition check, and any +constraint or predicate checks associated with in out or out parameters are performed in an arbitrary order. + +If a precondition or postcondition check fails, the exception is raised at the point of the call; the exception +cannot be handled inside the called subprogram or entry. Similarly, any exception raised by the evaluation +of a precondition or postcondition expression is raised at the point of call. + +For any subprogram or entry call (including dispatching calls), the checks that are performed to verify +specific precondition expressions and specific and class-wide postcondition expressions are determined by +those for the subprogram or entry actually invoked. Note that the class-wide postcondition expressions +verified by the postcondition check that is part of a call on a primitive subprogram of type T includes all +class-wide postcondition expressions originating in any progenitor of T, even if the primitive subprogram +called is inherited from a type T1 and some of the postcondition expressions do not apply to the +corresponding primitive subprogram of T1. + +The class-wide precondition check for a call to a subprogram or entry consists solely of checking the +class-wide precondition expressions that apply to the denoted callable entity (not necessarily the one that +is invoked). + +For a call via an access-to-subprogram value, all precondition and postcondition checks performed are +determined by the subprogram or entry denoted by the prefix of the Access attribute reference that +produced the value. + +NOTES +5 A precondition is checked just before the call. If another task can change any value that the precondition expression +depends on, the precondition need not hold within the subprogram or entry body. + +6.1.1 Preconditions and Postconditions + +13 December 2012 156 + + Ada Reference Manual — 2012 Edition + +6.2 Formal Parameter Modes + +A parameter_specification declares a formal parameter of mode in, in out, or out. + +Static Semantics + +A parameter is passed either by copy or by reference. When a parameter is passed by copy, the formal +parameter denotes a separate object from the actual parameter, and any information transfer between the +two occurs only before and after executing the subprogram. When a parameter is passed by reference, the +formal parameter denotes (a view of) the object denoted by the actual parameter; reads and updates of the +formal parameter directly reference the actual parameter object. + +A type is a by-copy type if it is an elementary type, or if it is a descendant of a private type whose full type +is a by-copy type. A parameter of a by-copy type is passed by copy, unless the formal parameter is +explicitly aliased. + +A type is a by-reference type if it is a descendant of one of the following: + +• a tagged type; +• a task or protected type; +• an explicitly limited record type; +• a composite type with a subcomponent of a by-reference type; +• a private type whose full type is a by-reference type. + +A parameter of a by-reference type is passed by reference, as is an explicitly aliased parameter of any +type. Each value of a by-reference type has an associated object. For a parenthesized expression, +qualified_expression, or type_conversion, this object is the one associated with the operand. For a +conditional_expression, this object is the one associated with the evaluated dependent_expression. + +For other parameters, it is unspecified whether the parameter is passed by copy or by reference. + +Bounded (Run-Time) Errors + +If one name denotes a part of a formal parameter, and a second name denotes a part of a distinct formal +parameter or an object that is not part of a formal parameter, then the two names are considered distinct +access paths. If an object is of a type for which the parameter passing mechanism is not specified and is +not an explicitly aliased parameter, then it is a bounded error to assign to the object via one access path, +and then read the value of the object via a distinct access path, unless the first access path denotes a part of +a formal parameter that no longer exists at the point of the second access (due to leaving the corresponding +callable construct). The possible consequences are that Program_Error is raised, or the newly assigned +value is read, or some old value of the object is read. + +1 + +2 + +3/3 + +4 + +5 + +6 + +7/3 + +8 + +9 + +10/3 + +11/3 + +12/3 + +NOTES +6 A formal parameter of mode in is a constant view (see 3.3); it cannot be updated within the subprogram_body. + +13 + +157 13 December 2012 + +Formal Parameter Modes 6.2 + + Ada Reference Manual — 2012 Edition + +6.3 Subprogram Bodies + +1 + +A subprogram_body specifies the execution of a subprogram. + +Syntax + +2/3 + +3 + +4 + +5 + +6 + +7 + +8 + +9 + +10 + +11 + +subprogram_body ::= + [overriding_indicator] + subprogram_specification + [aspect_specification] is + declarative_part + begin + handled_sequence_of_statements + end [designator]; + +If a designator appears at the end of a subprogram_body, it shall repeat the defining_designator of +the subprogram_specification. + +Legality Rules + +In contrast to other bodies, a subprogram_body need not be the completion of a previous declaration, in +which case the body declares the subprogram. If the body is a completion, it shall be the completion of a +subprogram_declaration or generic_subprogram_declaration. The profile of a subprogram_body that +completes a declaration shall conform fully to that of the declaration. + +Static Semantics + +A subprogram_body is considered a declaration. It can either complete a previous declaration, or itself be +the initial declaration of the subprogram. + +Dynamic Semantics + +The elaboration of a nongeneric subprogram_body has no other effect than to establish that the +subprogram can from then on be called without failing the Elaboration_Check. + +The execution of a subprogram_body is invoked by a subprogram call. For this execution the +declarative_part is elaborated, and the handled_sequence_of_statements is then executed. + +Example of procedure body: + +Examples + +procedure Push(E : in Element_Type; S : in out Stack) is +begin + if S.Index = S.Size then + raise Stack_Overflow; + else + S.Index := S.Index + 1; + S.Space(S.Index) := E; + end if; +end Push; + +Example of a function body: + +function Dot_Product(Left, Right : Vector) return Real is + Sum : Real := 0.0; +begin + Check(Left'First = Right'First and Left'Last = Right'Last); + for J in Left'Range loop + Sum := Sum + Left(J)*Right(J); + end loop; + return Sum; +end Dot_Product; + +6.3 Subprogram Bodies + +13 December 2012 158 + + Ada Reference Manual — 2012 Edition + +6.3.1 Conformance Rules + +When subprogram profiles are given in more than one place, they are required to conform in one of four +ways: type conformance, mode conformance, subtype conformance, or full conformance. + +1 + +Static Semantics + +As explained in B.1, “Interfacing Aspects”, a convention can be specified for an entity. Unless this +International Standard states otherwise, the default convention of an entity is Ada. For a callable entity or +access-to-subprogram type, the convention is called the calling convention. The following conventions are +defined by the language: + +2/1 + +• The default calling convention for any subprogram not listed below is Ada. The Convention + +3/3 + +aspect may be specified to override the default calling convention (see B.1). + +• The Intrinsic calling convention represents subprograms that are “built in” to the compiler. The + +default calling convention is Intrinsic for the following: + +• an enumeration literal; + +• a "/=" operator declared implicitly due to the declaration of "=" (see 6.6); + +• any other implicitly declared subprogram unless it is a dispatching operation of a tagged + +type; + +• an inherited subprogram of a generic formal tagged type with unknown discriminants; + +• an attribute that is a subprogram; + +• a subprogram declared immediately within a protected_body; + +• any prefixed view of a subprogram (see 4.1.3). + + The Access attribute is not allowed for Intrinsic subprograms. +• The default calling convention is protected for a protected subprogram, and for an access-to- + +subprogram type with the reserved word protected in its definition. + +• The default calling convention is entry for an entry. +• The calling convention for an anonymous access-to-subprogram parameter or anonymous +access-to-subprogram result is protected if the reserved word protected appears in its definition; +otherwise, it is the convention of the subprogram that contains the parameter. + +• If not specified above as Intrinsic, the calling convention for any inherited or overriding +dispatching operation of a tagged type is that of the corresponding subprogram of the parent +type. The default calling convention for a new dispatching operation of a tagged type is the +convention of the type. + +Of these four conventions, only Ada and Intrinsic are allowed as a convention_identifier in the +specification of a Convention aspect. + +Two profiles are type conformant if they have the same number of parameters, and both have a result if +either does, and corresponding parameter and result types are the same, or, for access parameters or access +results, corresponding designated types are the same, or corresponding designated profiles are type +conformant. + +Two profiles are mode conformant if: + +they are type conformant; and + +• +• corresponding parameters have identical modes and both or neither are explicitly aliased + +parameters; and + +4 + +5 + +6 + +7 + +8 + +9 + +10/2 + +10.1/2 + +11 + +12 + +13 + +13.1/3 + +13.2/1 + +14/3 + +15/2 + +16/3 + +16.1/3 + +16.2/3 + +159 13 December 2012 + +Conformance Rules 6.3.1 + + Ada Reference Manual — 2012 Edition + +16.3/3 + +17/3 + +18/3 + +18.1/3 + +18.2/3 + +18.3/3 + +• for corresponding access parameters and any access result type, the designated subtypes +statically match and either both or neither are access-to-constant, or the designated profiles are +subtype conformant. + +Two profiles are subtype conformant if they are mode conformant, corresponding subtypes of the profile +statically match, and the associated calling conventions are the same. The profile of a generic formal +subprogram is not subtype conformant with any other profile. + +Two profiles are fully conformant if they are subtype conformant, if they have access-to-subprogram +results whose designated profiles are fully conformant, and for corresponding parameters: + +they have the same names; and + +• +• both or neither have null_exclusions; and +• neither have default_expressions, or they both have default_expressions that are fully + +conformant with one another; and + +18.4/3 + +• for access-to-subprogram parameters, the designated profiles are fully conformant. + +19 + +20 + +21 + +Two expressions are fully conformant if, after replacing each use of an operator with the equivalent +function_call: + +• each constituent construct of one corresponds to an instance of the same syntactic category in +the other, except that an expanded name may correspond to a direct_name (or character_literal) +or to a different expanded name in the other; and + +• each direct_name, character_literal, and selector_name that is not part of the prefix of an +expanded name in one denotes the same declaration as the corresponding direct_name, +character_literal, or selector_name in the other; and + +21.1/3 + +• each attribute_designator in one is the same as the corresponding attribute_designator in the + +other; and + +22 + +23 + +24 + +• each primary that is a literal in one has the same value as the corresponding literal in the other. + +Two known_discriminant_parts are fully conformant if they have the same number of discriminants, and +discriminants in the same positions have the same names, statically matching subtypes, and +default_expressions that are fully conformant with one another. + +Two discrete_subtype_definitions are fully conformant if they are both subtype_indications or are both +ranges, the subtype_marks (if any) denote the same subtype, and the corresponding simple_expressions +of the ranges (if any) fully conform. + +24.1/2 + +The prefixed view profile of a subprogram is the profile obtained by omitting the first parameter of that +subprogram. There is no prefixed view profile for a parameterless subprogram. For the purposes of +defining subtype and mode conformance, the convention of a prefixed view profile is considered to match +that of either an entry or a protected operation. + +25 + +An implementation may declare an operator declared in a language-defined library unit to be intrinsic. + +Implementation Permissions + +6.3.1 Conformance Rules + +13 December 2012 160 + + Ada Reference Manual — 2012 Edition + +6.3.2 Inline Expansion of Subprograms + +Subprograms may be expanded in line at the call site. + +Paragraphs 2 through 4 were moved to Annex J, “Obsolescent Features”. + +Static Semantics + +For a callable entity or a generic subprogram, the following language-defined representation aspect may +be specified: + +Inline + +The type of aspect Inline is Boolean. When aspect Inline is True for a callable entity, inline +expansion is desired for all calls to that entity. When aspect Inline is True for a generic +subprogram, inline expansion is desired for all calls to all instances of that generic +subprogram. + +1 + +5/3 + +5.1/3 + +If directly specified, the aspect_definition shall be a static expression. This aspect is never +inherited; if not directly specified, the aspect is False. + +5.2/3 + +For each call, an implementation is free to follow or to ignore the recommendation determined by the +Inline aspect. + +6/3 + +Implementation Permissions + +6.4 Subprogram Calls + +A subprogram call is either a procedure_call_statement or a function_call; it invokes the execution of the +subprogram_body. The call specifies the association of the actual parameters, if any, with formal +parameters of the subprogram. + +Syntax + +procedure_call_statement ::= + procedure_name; + | procedure_prefix actual_parameter_part; + +function_call ::= + function_name + | function_prefix actual_parameter_part + +actual_parameter_part ::= + (parameter_association {, parameter_association}) + +parameter_association ::= + [formal_parameter_selector_name =>] explicit_actual_parameter + +explicit_actual_parameter ::= expression | variable_name + +A parameter_association is named or positional according to whether or not the formal_parameter_- +selector_name is specified. Any positional associations shall precede any named associations. +Named associations are not allowed if the prefix in a subprogram call is an attribute_reference. + +1 + +2 + +3 + +4 + +5 + +6 + +7 + +The name or prefix given in a procedure_call_statement shall resolve to denote a callable entity that is a +procedure, or an entry renamed as (viewed as) a procedure. The name or prefix given in a function_call +shall resolve to denote a callable entity that is a function. The name or prefix shall not resolve to denote an + +8/2 + +Name Resolution Rules + +161 13 December 2012 + +Inline Expansion of Subprograms 6.3.2 + + + Ada Reference Manual — 2012 Edition + +abstract subprogram unless it is also a dispatching subprogram. When there is an actual_parameter_part, +the prefix can be an implicit_dereference of an access-to-subprogram value. + +9 + +A subprogram call shall contain at most one association for each formal parameter. Each formal parameter +without an association shall have a default_expression (in the profile of the view denoted by the name or +prefix). This rule is an overloading rule (see 8.6). + +Dynamic Semantics + +10/2 + +For the execution of a subprogram call, the name or prefix of the call is evaluated, and each parameter_- +association is evaluated (see 6.4.1). If a default_expression is used, an implicit parameter_association is +assumed for this rule. These evaluations are done in an arbitrary order. The subprogram_body is then +executed, or a call on an entry or protected subprogram is performed (see 3.9.2). Finally, if the subprogram +completes normally, then after it is left, any necessary assigning back of formal to actual parameters +occurs (see 6.4.1). + +10.1/2 + +If the name or prefix of a subprogram call denotes a prefixed view (see 4.1.3), the subprogram call is +equivalent to a call on the underlying subprogram, with the first actual parameter being provided by the +prefix of the prefixed view (or the Access attribute of this prefix if the first formal parameter is an access +parameter), and the remaining actual parameters given by the actual_parameter_part, if any. + +11/2 + +12/2 + +13 + +14 + +15 + +16 + +17 + +18 + +19 + +20/3 + +21 + +22 + +23/3 + +The exception Program_Error is raised at the point of a function_call if the function completes normally +without executing a return statement. + +A function_call denotes a constant, as defined in 6.5; the nominal subtype of the constant is given by the +nominal subtype of the function result. + +Examples of procedure calls: + +Examples + +Traverse_Tree; -- see 6.1 +Print_Header(128, Title, True); -- see 6.1 +Switch(From => X, To => Next); -- see 6.1 +Print_Header(128, Header => Title, Center => True); -- see 6.1 +Print_Header(Header => Title, Center => True, Pages => 128); -- see 6.1 + +Examples of function calls: + +Dot_Product(U, V) -- see 6.1 and 6.3 +Clock -- see 9.6 +F.all -- presuming F is of an access-to-subprogram type — see 3.10 + +Examples of procedures with default expressions: + +procedure Activate(Process : in Process_Name; + After : in Process_Name := No_Process; + Wait : in Duration := 0.0; + Prior : in Boolean := False); +procedure Pair(Left, Right : in Person_Name := new Person(M)); -- see 3.10.1 + +Examples of their calls: +Activate(X); +Activate(X, After => Y); +Activate(X, Wait => 60.0, Prior => True); +Activate(X, Y, 10.0, False); + +Pair; +Pair(Left => new Person(F), Right => new Person(M)); + +6.4 Subprogram Calls + +13 December 2012 162 + + Ada Reference Manual — 2012 Edition + +NOTES +7 If a default_expression is used for two or more parameters in a multiple parameter_specification, the default_- +expression is evaluated once for each omitted parameter. Hence in the above examples, the two calls of Pair are +equivalent. + +Examples + +Examples of overloaded subprograms: + +procedure Put(X : in Integer); +procedure Put(X : in String); +procedure Set(Tint : in Color); +procedure Set(Signal : in Light); + +Examples of their calls: + +Put(28); +Put("no possible ambiguity here"); + +Set(Tint => Red); +Set(Signal => Red); +Set(Color'(Red)); +-- Set(Red) would be ambiguous since Red may +-- denote a value either of type Color or of type Light + +6.4.1 Parameter Associations + +A parameter association defines the association between an actual parameter and a formal parameter. + +Name Resolution Rules + +The formal_parameter_selector_name of a named parameter_association shall resolve to denote a +parameter_specification of the view being called; this is the formal parameter of the association. The +formal parameter for a positional parameter_association is the parameter with the corresponding position +in the formal part of the view being called. + +The actual parameter is either the explicit_actual_parameter given in a parameter_association for a +given formal parameter, or the corresponding default_expression if no parameter_association is given +for the formal parameter. The expected type for an actual parameter is the type of the corresponding +formal parameter. + +If the mode is in, the actual is interpreted as an expression; otherwise, the actual is interpreted only as a +name, if possible. + +If the mode is in out or out, the actual shall be a name that denotes a variable. + +Legality Rules + +If the formal parameter is an explicitly aliased parameter, the type of the actual parameter shall be tagged +or the actual parameter shall be an aliased view of an object. Further, if the formal parameter subtype F is +untagged: + +• +• + +the subtype F shall statically match the nominal subtype of the actual object; or + +the subtype F shall be unconstrained, discriminated in its full view, and unconstrained in any +partial view. + +In a function call, the accessibility level of the actual object for each explicitly aliased parameter shall not +be statically deeper than the accessibility level of the master of the call (see 3.10.2). + +Two names are known to denote the same object if: + +163 13 December 2012 + +Subprogram Calls 6.4 + +24 + +25 + +26 + +27 + +28 + +29 + +30 + +31 + +1 + +2/3 + +3 + +4 + +5 + +6/3 + +6.1/3 + +6.2/3 + +6.3/3 + +6.4/3 + + Ada Reference Manual — 2012 Edition + +6.5/3 + +6.6/3 + +• both names statically denote the same stand-alone object or parameter; or +• both names are selected_components, their prefixes are known to denote the same object, and + +their selector_names denote the same component; or + +6.7/3 + +• both names are dereferences (implicit or explicit) and the dereferenced names are known to + +denote the same object; or + +6.8/3 + +• both names are indexed_components, their prefixes are known to denote the same object, and +each of the pairs of corresponding index values are either both static expressions with the same +static value or both names that are known to denote the same object; or + +6.9/3 + +• both names are slices, their prefixes are known to denote the same object, and the two slices + +have statically matching index constraints; or + +6.10/3 + +• one of the two names statically denotes a renaming declaration whose renamed object_name is +known to denote the same object as the other, the prefix of any dereference within the renamed +object_name is not a variable, and any expression within the renamed object_name contains no +references to variables nor calls on nonstatic functions. + +6.11/3 + +Two names are known to refer to the same object if + +6.12/3 + +6.13/3 + +• The two names are known to denote the same object; or +• One of the names is a selected_component, indexed_component, or slice and its prefix is + +known to refer to the same object as the other name; or + +6.14/3 + +• One of the two names statically denotes a renaming declaration whose renamed object_name is + +known to refer to the same object as the other name. + +6.15/3 + +6.16/3 + +6.17/3 + +6.18/3 + +If a call C has two or more parameters of mode in out or out that are of an elementary type, then the call is +legal only if: + +• For each name N that is passed as a parameter of mode in out or out to the call C, there is no +other name among the other parameters of mode in out or out to C that is known to denote the +same object. + +If a construct C has two or more direct constituents that are names or expressions whose evaluation may +occur in an arbitrary order, at least one of which contains a function call with an in out or out parameter, +then the construct is legal only if: + +• For each name N that is passed as a parameter of mode in out or out to some inner function call +C2 (not including the construct C itself), there is no other name anywhere within a direct +constituent of the construct C other than the one containing C2, that is known to refer to the +same object. + +6.19/3 + +For the purposes of checking this rule: + +6.20/3 + +6.21/3 + +6.22/3 + +• For an array aggregate, an expression associated with a discrete_choice_list that has two or +more discrete choices, or that has a nonstatic range, is considered as two or more separate +occurrences of the expression; + +• For a record aggregate: + +• The expression of a record_component_association is considered to occur once for each + +associated component; and + +6.23/3 + +• The default_expression for each record_component_association with <> for which the + +associated component has a default_expression is considered part of the aggregate; + +6.24/3 + +• For a call, any default_expression evaluated as part of the call is considered part of the call. + +6.4.1 Parameter Associations + +13 December 2012 164 + + Ada Reference Manual — 2012 Edition + +Dynamic Semantics + +For the evaluation of a parameter_association: +• The actual parameter is first evaluated. +• For an access parameter, the access_definition is elaborated, which creates the anonymous + +access type. + +• For a parameter (of any mode) that is passed by reference (see 6.2), a view conversion of the +actual parameter to the nominal subtype of the formal parameter is evaluated, and the formal +parameter denotes that conversion. + +• For an in or in out parameter that is passed by copy (see 6.2), the formal parameter object is +created, and the value of the actual parameter is converted to the nominal subtype of the formal +parameter and assigned to the formal. + +• For an out parameter that is passed by copy, the formal parameter object is created, and: + +• For an access type, the formal parameter is initialized from the value of the actual, without +checking that the value satisfies any constraint, any predicate, or any exclusion of the null +value; + +• For a scalar type that has the Default_Value aspect specified, the formal parameter is +initialized from the value of the actual, without checking that the value satisfies any +constraint or any predicate; + +• For a composite type with discriminants or that has implicit initial values for any +subcomponents (see 3.3.1), the behavior is as for an in out parameter passed by copy. +• For any other type, the formal parameter is uninitialized. If composite, a view conversion of +the actual parameter to the nominal subtype of the formal is evaluated (which might raise +Constraint_Error), and the actual subtype of the formal is that of the view conversion. If +elementary, the actual subtype of the formal is given by its nominal subtype. + +• In a function call, for each explicitly aliased parameter, a check is made that the accessibility +level of the master of the actual object is not deeper than that of the master of the call (see +3.10.2). + +A formal parameter of mode in out or out with discriminants is constrained if either its nominal subtype or +the actual parameter is constrained. + +After normal completion and leaving of a subprogram, for each in out or out parameter that is passed by +copy, the value of the formal parameter is converted to the subtype of the variable given as the actual +parameter and assigned to it. These conversions and assignments occur in an arbitrary order. + +Erroneous Execution + +If the nominal subtype of a formal parameter with discriminants is constrained or indefinite, and the +parameter is passed by reference, then the execution of the call is erroneous if the value of any +discriminant of the actual is changed while the formal parameter exists (that is, before leaving the +corresponding callable construct). + +7 + +8 + +9 + +10 + +11 + +12 + +13/3 + +13.1/3 + +14 + +15 + +15.1/3 + +16 + +17 + +18/3 + +165 13 December 2012 + +Parameter Associations 6.4.1 + + Ada Reference Manual — 2012 Edition + +6.5 Return Statements + +1/2 + +A simple_return_statement or extended_return_statement (collectively called a return statement) is +used to complete the execution of the innermost enclosing subprogram_body, entry_body, or accept_- +statement. + +2/2 + +2.1/3 + +2.2/3 + +Syntax +simple_return_statement ::= return [expression]; + +extended_return_object_declaration ::= + defining_identifier : [aliased][constant] return_subtype_indication [:= expression] + +extended_return_statement ::= + return extended_return_object_declaration [do + handled_sequence_of_statements + end return]; + +2.3/2 + +return_subtype_indication ::= subtype_indication | access_definition + +3/2 + +4/2 + +5/3 + +Name Resolution Rules + +The result subtype of a function is the subtype denoted by the subtype_mark, or defined by the +access_definition, after the reserved word return in the profile of the function. The expected type for the +expression, if any, of a simple_return_statement is the result type of the corresponding function. The +expected type for the expression of an extended_return_statement is that of the return_subtype_- +indication. + +Legality Rules + +A return statement shall be within a callable construct, and it applies to the innermost callable construct or +extended_return_statement that contains it. A return statement shall not be within a body that is within +the construct to which the return statement applies. + +A function body shall contain at least one return statement that applies to the function body, unless the +function contains code_statements. A simple_return_statement shall include an expression if and only +if it applies to a function body. An extended_return_statement shall apply to a function body. An +extended_return_statement with the reserved word constant shall include an expression. + +5.1/2 + +For an extended_return_statement that applies to a function body: + +5.2/3 + +5.3/2 + +5.4/3 + +• If the result subtype of the function is defined by a subtype_mark, the return_subtype_- +indication shall be a subtype_indication. The type of the subtype_indication shall be covered by +the result type of the function. The subtype defined by the subtype_indication shall be statically +compatible with the result subtype of the function; if the result type of the function is +elementary, the two subtypes shall statically match. If the result subtype of the function is +indefinite, then the subtype defined by the subtype_indication shall be a definite subtype, or +there shall be an expression. + +• If the result subtype of the function is defined by an access_definition, the return_subtype_- +indication shall be an access_definition. The subtype defined by the access_definition shall +statically match the result subtype of the function. The accessibility level of this anonymous +access subtype is that of the result subtype. + +• If the result subtype of the function is class-wide, the accessibility level of the type of the +subtype defined by the return_subtype_indication shall not be statically deeper than that of the +master that elaborated the function body. + +6.5 Return Statements + +13 December 2012 166 + + Ada Reference Manual — 2012 Edition + +For any return statement that applies to a function body: + +• If the result subtype of the function is limited, then the expression of the return statement (if + +any) shall meet the restrictions described in 7.5. + +• If the result subtype of the function is class-wide, the accessibility level of the type of the +expression (if any) of the return statement shall not be statically deeper than that of the master +that elaborated the function body. + +• If the subtype determined by the expression of the simple_return_statement or by the +return_subtype_indication has one or more access discriminants, the accessibility level of the +anonymous access type of each access discriminant shall not be statically deeper than that of the +master that elaborated the function body. + +5.5/3 + +5.6/3 + +5.7/3 + +5.8/3 + +If the keyword aliased is present in an extended_return_object_declaration, the type of the extended +return object shall be immutably limited. + +5.9/3 + +Static Semantics + +Within an extended_return_statement, the return object is declared with the given defining_identifier, +with the nominal subtype defined by the return_subtype_indication. An extended_return_statement with +the reserved word constant is a full constant declaration that declares the return object to be a constant +object. + +5.10/3 + +Dynamic Semantics + +For the execution of an extended_return_statement, the subtype_indication or access_definition is +elaborated. This creates the nominal subtype of the return object. If there is an expression, it is evaluated +and converted to the nominal subtype (which might raise Constraint_Error — see 4.6); the return object is +created and the converted value is assigned to the return object. Otherwise, the return object is created and +initialized by default as for a stand-alone object of its nominal subtype (see 3.3.1). If the nominal subtype +is indefinite, the return object is constrained by its initial value. A check is made that the value of the +return object belongs to the function result subtype. Constraint_Error is raised if this check fails. + +5.11/3 + +For the execution of a simple_return_statement, the expression (if any) is first evaluated, converted to +the result subtype, and then is assigned to the anonymous return object. + +If the return object has any parts that are tasks, the activation of those tasks does not occur until after the +function returns (see 9.2). + +If the result type of a function is a specific tagged type, the tag of the return object is that of the result +type. If the result type is class-wide, the tag of the return object is that of the type of the +subtype_indication if it is specific, or otherwise that of the value of the expression. A check is made that +the master of the type identified by the tag of the result includes the elaboration of the master that +elaborated the function body. If this check fails, Program_Error is raised. + +6/2 + +7/2 + +8/3 + +If the result subtype of the function is defined by an access_definition designating a specific tagged type +T, a check is made that the result value is null or the tag of the object designated by the result value +identifies T. Constraint_Error is raised if this check fails. + +8.1/3 + +Paragraphs 9 through 20 were deleted. + +If any part of the specific type of the return object of a function (or coextension thereof) has one or more +access discriminants whose value is not constrained by the result subtype of the function, a check is made +that the accessibility level of the anonymous access type of each access discriminant, as determined by the + +21/3 + +167 13 December 2012 + +Return Statements 6.5 + + Ada Reference Manual — 2012 Edition + +expression or the return_subtype_indication of the return statement, is not deeper than the level of the +master of the call (see 3.10.2). If this check fails, Program_Error is raised. + +22/3 + +For the execution of an extended_return_statement, the handled_sequence_of_statements is executed. +Within this handled_sequence_of_statements, the execution of a simple_return_statement that applies +to the extended_return_statement causes a transfer of control that completes the extended_return_- +statement. Upon completion of a return statement that applies to a callable construct by the normal +completion of a simple_return_statement or by reaching the end return of an extended_return_- +statement, a transfer of control is performed which completes the execution of the callable construct, and +returns to the caller. + +23/2 + +In the case of a function, the function_call denotes a constant view of the return object. + +Implementation Permissions + +24/3 + +For a function call used to initialize a composite object with a constrained nominal subtype or used to +initialize a return object that is built in place into such an object: + +24.1/3 + +24.2/3 + +• If the result subtype of the function is constrained, and conversion of an object of this subtype to +the subtype of the object being initialized would raise Constraint_Error, then Constraint_Error +may be raised before calling the function. + +• If the result subtype of the function is unconstrained, and a return statement is executed such that +the return object is known to be constrained, and conversion of the return object to the subtype +of the object being initialized would raise Constraint_Error, then Constraint_Error may be raised +at the point of the call (after abandoning the execution of the function body). + +25 + +Examples of return statements: + +Examples + +26/2 + +27 + +28/2 + +return; -- in a procedure body, entry_body, + -- accept_statement, or extended_return_statement +return Key_Value(Last_Index); -- in a function body +return Node : Cell do -- in a function body, see 3.10.1 for Cell + Node.Value := Result; + Node.Succ := Next_Node; +end return; + +6.5 Return Statements + +13 December 2012 168 + + Ada Reference Manual — 2012 Edition + +6.5.1 Nonreturning Procedures + +Specifying aspect No_Return to have the value True indicates that a procedure cannot return normally; it +may propagate an exception or loop forever. + +1/3 + +Paragraphs 2 and 3 were moved to Annex J, “Obsolescent Features”. + +Static Semantics + +For a procedure or generic procedure, the following language-defined representation aspect may be +specified: + +No_Return + +The type of aspect No_Return is Boolean. When aspect No_Return is True for an entity, the +entity is said to be nonreturning. + +If directly specified, the aspect_definition shall be a static expression. This aspect is never +inherited; if not directly specified, the aspect is False. + +If a generic procedure is nonreturning, then so are its instances. If a procedure declared within a generic +unit is nonreturning, then so are the corresponding copies of that procedure in instances. + +Aspect No_Return shall not be specified for a null procedure nor an instance of a generic unit. + +A return statement shall not apply to a nonreturning procedure or generic procedure. + +Legality Rules + +A procedure shall be nonreturning if it overrides a dispatching nonreturning procedure. In addition to the +places where Legality Rules normally apply (see 12.3), this rule applies also in the private part of an +instance of a generic unit. + +If a renaming-as-body completes a nonreturning procedure declaration, then the renamed procedure shall +be nonreturning. + +3.1/3 + +3.2/3 + +3.3/3 + +3.4/3 + +4/3 + +5/2 + +6/2 + +7/2 + +Paragraph 8 was deleted. + +If the body of a nonreturning procedure completes normally, Program_Error is raised at the point of the +call. + +9/2 + +Dynamic Semantics + +procedure Fail(Msg : String) -- raises Fatal_Error exception + with No_Return; + -- Inform compiler and reader that procedure never returns normally + +Examples + +10/3 + +169 13 December 2012 + +Nonreturning Procedures 6.5.1 + + + Ada Reference Manual — 2012 Edition + +6.6 Overloading of Operators + +1 + +2 + +3/3 + +4 + +5 + +An operator is a function whose designator is an operator_symbol. Operators, like other functions, may +be overloaded. + +Each use of a unary or binary operator is equivalent to a function_call with function_prefix being the +corresponding operator_symbol, and with (respectively) one or two positional actual parameters being the +operand(s) of the operator (in order). + +Name Resolution Rules + +Legality Rules + +The subprogram_specification of a unary or binary operator shall have one or two parameters, +respectively. The parameters shall be of mode in. A generic function instantiation whose designator is an +operator_symbol is only allowed if the specification of the generic function has the corresponding number +of parameters, and they are all of mode in. + +Default_expressions are not allowed for the parameters of an operator (whether the operator is declared +with an explicit subprogram_specification or by a generic_instantiation). + +An explicit declaration of "/=" shall not have a result type of the predefined type Boolean. + +6/3 + +An explicit declaration of "=" whose result type is Boolean implicitly declares an operator "/=" that gives +the complementary result. + +Static Semantics + +7 + +8 + +9 + +NOTES +8 The operators "+" and "–" are both unary and binary operators, and hence may be overloaded with both one- and two- +parameter functions. + +Examples of user-defined operators: + +function "+" (Left, Right : Matrix) return Matrix; +function "+" (Left, Right : Vector) return Vector; + +Examples + +-- assuming that A, B, and C are of the type Vector +-- the following two statements are equivalent: + +A := B + C; +A := "+"(B, C); + +6.6 Overloading of Operators + +13 December 2012 170 + + + + Ada Reference Manual — 2012 Edition + +6.7 Null Procedures + +A null_procedure_declaration provides a shorthand to declare a procedure with an empty body. + +null_procedure_declaration ::= + [overriding_indicator] + procedure_specification is null + [aspect_specification]; + +Syntax + +Legality Rules + +1/2 + +2/3 + +If a null_procedure_declaration is a completion, it shall be the completion of a subprogram_declaration +or generic_subprogram_declaration. The profile of a null_procedure_declaration that completes a +declaration shall conform fully to that of the declaration. + +2.1/3 + +A null_procedure_declaration declares a null procedure. A completion is not allowed for a +null_procedure_declaration; however, a null_procedure_declaration can complete a previous declaration. + +3/3 + +Static Semantics + +Dynamic Semantics + +The execution of a null procedure is invoked by a subprogram call. For the execution of a subprogram call +on a null procedure, the execution of the subprogram_body has no effect. + +The elaboration of a null_procedure_declaration has no other effect than to establish that the null +procedure can be called without failing the Elaboration_Check. + +procedure Simplify(Expr : in out Expression) is null; -- see 3.9 +-- By default, Simplify does nothing, but it may be overridden in extensions of Expression + +Examples + +4/2 + +5/3 + +6/2 + +171 13 December 2012 + +Null Procedures 6.7 + + Ada Reference Manual — 2012 Edition + +6.8 Expression Functions + +1/3 + +An expression_function_declaration provides a shorthand to declare a function whose body consists of a +single return statement. + +2/3 + +expression_function_declaration ::= + [overriding_indicator] + function_specification is + (expression) + [aspect_specification]; + +Syntax + +3/3 + +The expected type for the expression of an expression_function_declaration is the result type (see 6.5) of +the function. + +Name Resolution Rules + +Legality Rules + +4/3 + +5/3 + +6/3 + +7/3 + +If an expression_function_declaration +the completion of a +subprogram_declaration or generic_subprogram_declaration. The profile of an expression_function_- +declaration that completes a declaration shall conform fully to that of the declaration. + +is a completion, + +it shall be + +If the result subtype has one or more unconstrained access discriminants, the accessibility level of the +anonymous access type of each access discriminant, as determined by the expression of the expression +function, shall not be statically deeper than that of the master that elaborated the expression_function_- +declaration. + +An expression_function_declaration declares an expression function. A completion is not allowed for an +expression_function_declaration; however, an expression_function_declaration can complete a previous +declaration. + +Static Semantics + +Dynamic Semantics + +The execution of an expression function is invoked by a subprogram call. For the execution of a +subprogram call on an expression function, the execution of the subprogram_body executes an implicit +function body containing only a simple_return_statement whose expression is that of the expression +function. + +8/3 + +The elaboration of an expression_function_declaration has no other effect than to establish that the +expression function can be called without failing the Elaboration_Check. + +9/3 + +function Is_Origin (P : in Point) return Boolean is -- see 3.9 + (P.X = 0.0 and P.Y = 0.0); + +Examples + +6.8 Expression Functions + +13 December 2012 172 + + Ada Reference Manual — 2012 Edition + +7 Packages + +Packages are program units that allow the specification of groups of logically related entities. Typically, a +package contains the declaration of a type (often a private type or private extension) along with the +declarations of primitive subprograms of the type, which can be called from outside the package, while +their inner workings remain hidden from outside users. + +1 + +7.1 Package Specifications and Declarations + +A package is generally provided in two parts: a package_specification and a package_body. Every +package has a package_specification, but not all packages have a package_body. + +1 + +package_declaration ::= package_specification; + +Syntax + +package_specification ::= + package defining_program_unit_name + [aspect_specification] is + {basic_declarative_item} + [private + {basic_declarative_item}] + end [[parent_unit_name.]identifier] + +If an identifier or parent_unit_name.identifier appears at the end of a package_specification, then +this sequence of lexical elements shall repeat the defining_program_unit_name. + +Legality Rules + +A package_declaration or generic_package_declaration requires a completion (a body) if it contains any +basic_declarative_item +its +package_specification. + +requires a completion, but whose completion + +is not + +that + +in + +Static Semantics + +The first list of basic_declarative_items of a package_specification of a package other than a generic +formal package is called the visible part of the package. The optional list of basic_declarative_items after +the reserved word private (of any package_specification) is called the private part of the package. If the +reserved word private does not appear, the package has an implicit empty private part. Each list of +basic_declarative_items of a package_specification forms a declaration list of the package. + +An entity declared in the private part of a package is visible only within the declarative region of the +package itself (including any child units — see 10.1.1). In contrast, expanded names denoting entities +declared in the visible part can be used even outside the package; furthermore, direct visibility of such +entities can be achieved by means of use_clauses (see 4.1.3 and 8.4). + +Dynamic Semantics + +The elaboration of a package_declaration consists of the elaboration of its basic_declarative_items in the +given order. + +NOTES +1 The visible part of a package contains all the information that another program unit is able to know about the package. + +2 If a declaration occurs immediately within the specification of a package, and the declaration has a corresponding +completion that is a body, then that body has to occur immediately within the body of the package. + +173 13 December 2012 + +Packages 7 + +2 + +3/3 + +4 + +5/2 + +6/2 + +7 + +8 + +9 + +10 + + 11 + +12 + +13 + +14 + +15 + +16 + +17 + +1 + +2/3 + +3 + +4 + +5/3 + +Ada Reference Manual — 2012 Edition + +Example of a package declaration: + +Examples + +package Rational_Numbers is + type Rational is + record + Numerator : Integer; + Denominator : Positive; + end record; + function "="(X,Y : Rational) return Boolean; + function "/" (X,Y : Integer) return Rational; -- to construct a rational number + function "+" (X,Y : Rational) return Rational; + function "-" (X,Y : Rational) return Rational; + function "*" (X,Y : Rational) return Rational; + function "/" (X,Y : Rational) return Rational; +end Rational_Numbers; + +There are also many examples of package declarations in the predefined language environment (see Annex +A). + +7.2 Package Bodies + +In contrast to the entities declared in the visible part of a package, the entities declared in the +package_body are visible only within the package_body itself. As a consequence, a package with a +package_body can be used for the construction of a group of related subprograms in which the logical +operations available to clients are clearly isolated from the internal entities. + +Syntax + +package_body ::= + package body defining_program_unit_name + [aspect_specification] is + declarative_part + [begin + handled_sequence_of_statements] + end [[parent_unit_name.]identifier]; + +If an identifier or parent_unit_name.identifier appears at the end of a package_body, then this +sequence of lexical elements shall repeat the defining_program_unit_name. + +Legality Rules + +A package_body shall be the completion of a previous package_declaration or generic_package_- +declaration. A library package_declaration or library generic_package_declaration shall not have a +body unless it requires a body; pragma Elaborate_Body can be used to require a library_unit_declaration +to have a body (see 10.2.1) if it would not otherwise require one. + +Static Semantics + +In any package_body without statements there is an implicit null_statement. For any package_- +declaration without an explicit completion, there is an implicit package_body containing a single +null_statement. For a noninstance, nonlibrary package, this body occurs at the end of the declarative_part +of the innermost enclosing program unit or block_statement; if there are several such packages, the order +of the implicit package_bodies is unspecified. (For an instance, the implicit package_body occurs at the +place of the instantiation (see 12.3). For a library package, the place is partially determined by the +elaboration dependences (see Clause 10).) + +7.1 Package Specifications and Declarations + +13 December 2012 174 + + Ada Reference Manual — 2012 Edition + +For the elaboration of a nongeneric package_body, its declarative_part is first elaborated, and its +handled_sequence_of_statements is then executed. + +Dynamic Semantics + +NOTES +3 A variable declared in the body of a package is only visible within this body and, consequently, its value can only be +changed within the package_body. In the absence of local tasks, the value of such a variable remains unchanged between +calls issued from outside the package to subprograms declared in the visible part. The properties of such a variable are +similar to those of a “static” variable of C. + +4 The elaboration of the body of a subprogram explicitly declared in the visible part of a package is caused by the +elaboration of the body of the package. Hence a call of such a subprogram by an outside program unit raises the exception +Program_Error if the call takes place before the elaboration of the package_body (see 3.11). + +Example of a package body (see 7.1): + +Examples + +package body Rational_Numbers is + procedure Same_Denominator (X,Y : in out Rational) is + begin + -- reduces X and Y to the same denominator: + ... + end Same_Denominator; + function "="(X,Y : Rational) return Boolean is + U : Rational := X; + V : Rational := Y; + begin + Same_Denominator (U,V); + return U.Numerator = V.Numerator; + end "="; + function "/" (X,Y : Integer) return Rational is + begin + if Y > 0 then + return (Numerator => X, Denominator => Y); + else + return (Numerator => -X, Denominator => -Y); + end if; + end "/"; + function "+" (X,Y : Rational) return Rational is ... end "+"; + function "-" (X,Y : Rational) return Rational is ... end "-"; + function "*" (X,Y : Rational) return Rational is ... end "*"; + function "/" (X,Y : Rational) return Rational is ... end "/"; +end Rational_Numbers; + +7.3 Private Types and Private Extensions + +The declaration (in the visible part of a package) of a type as a private type or private extension serves to +separate the characteristics that can be used directly by outside program units (that is, the logical +properties) from other characteristics whose direct use is confined to the package (the details of the +definition of the type itself). See 3.9.1 for an overview of type extensions. + +private_type_declaration ::= + type defining_identifier [discriminant_part] is [[abstract] tagged] [limited] private + [aspect_specification]; + +Syntax + +175 13 December 2012 + +Package Bodies 7.2 + +6 + +7 + +8 + +9 + +10 + +11 + +12 + +13 + +14 + +15 + +1 + +2/3 + + 3/3 + +4 + +5 + +6/2 + +7 + +Ada Reference Manual — 2012 Edition + +private_extension_declaration ::= + type defining_identifier [discriminant_part] is + [abstract] [limited | synchronized] new ancestor_subtype_indication + [and interface_list] with private + [aspect_specification]; + +Legality Rules + +A private_type_declaration or private_extension_declaration declares a partial view of the type; such a +declaration is allowed only as a declarative_item of the visible part of a package, and it requires a +completion, which shall be a full_type_declaration that occurs as a declarative_item of the private part of +the package. The view of the type declared by the full_type_declaration is called the full view. A generic +formal private type or a generic formal private extension is also a partial view. + +A type shall be completely defined before it is frozen (see 3.11.1 and 13.14). Thus, neither the declaration +of a variable of a partial view of a type, nor the creation by an allocator of an object of the partial view are +allowed before the full declaration of the type. Similarly, before the full declaration, the name of the +partial view cannot be used in a generic_instantiation or in a representation item. + +A private type is limited if its declaration includes the reserved word limited; a private extension is limited +if its ancestor type is a limited type that is not an interface type, or if the reserved word limited or +synchronized appears in its definition. If the partial view is nonlimited, then the full view shall be +nonlimited. If a tagged partial view is limited, then the full view shall be limited. On the other hand, if an +untagged partial view is limited, the full view may be limited or nonlimited. + +If the partial view is tagged, then the full view shall be tagged. On the other hand, if the partial view is +untagged, then the full view may be tagged or untagged. In the case where the partial view is untagged and +the full view is tagged, no derivatives of the partial view are allowed within the immediate scope of the +partial view; derivatives of the full view are allowed. + +7.1/2 + +If a full type has a partial view that is tagged, then: + +7.2/2 + +7.3/2 + +8 + +• + +• + +the partial view shall be a synchronized tagged type (see 3.9.4) if and only if the full type is a +synchronized tagged type; + +the partial view shall be a descendant of an interface type (see 3.9.4) if and only if the full type +is a descendant of the interface type. + +The ancestor subtype of a private_extension_declaration is the subtype defined by the ancestor_- +subtype_indication; the ancestor type shall be a specific tagged type. The full view of a private extension +shall be derived (directly or indirectly) from the ancestor type. In addition to the places where Legality +Rules normally apply (see 12.3), the requirement that the ancestor be specific applies also in the private +part of an instance of a generic unit. + +8.1/2 + +If the reserved word limited appears in a private_extension_declaration, the ancestor type shall be a +limited type. If the reserved word synchronized appears in a private_extension_declaration, the ancestor +type shall be a limited interface. + +9 + +10 + +If the declaration of a partial view includes a known_discriminant_part, then the full_type_declaration +shall have a fully conforming (explicit) known_discriminant_part (see 6.3.1, “Conformance Rules”). The +ancestor subtype may be unconstrained; the parent subtype of the full view is required to be constrained +(see 3.7). + +If a private extension inherits known discriminants from the ancestor subtype, then the full view shall also +inherit its discriminants from the ancestor subtype, and the parent subtype of the full view shall be +constrained if and only if the ancestor subtype is constrained. + +7.3 Private Types and Private Extensions + +13 December 2012 176 + + Ada Reference Manual — 2012 Edition + +If the full_type_declaration for a private extension includes a derived_type_definition, then the reserved +word limited shall appear in the full_type_declaration if and only if it also appears in the +private_extension_declaration. + +10.1/3 + +If a partial view has unknown discriminants, then the full_type_declaration may define a definite or an +indefinite subtype, with or without discriminants. + +If a partial view has neither known nor unknown discriminants, then the full_type_declaration shall define +a definite subtype. + +If the ancestor subtype of a private extension has constrained discriminants, then the parent subtype of the +full view shall impose a statically matching constraint on those discriminants. + +Static Semantics + +A private_type_declaration declares a private type and its first subtype. Similarly, a private_extension_- +declaration declares a private extension and its first subtype. + +A declaration of a partial view and the corresponding full_type_declaration define two views of a single +type. The declaration of a partial view together with the visible part define the operations that are available +to outside program units; the declaration of the full view together with the private part define other +operations whose direct use is possible only within the declarative region of the package itself. Moreover, +within the scope of the declaration of the full view, the characteristics (see 3.4) of the type are determined +by the full view; in particular, within its scope, the full view determines the classes that include the type, +which components, entries, and protected subprograms are visible, what attributes and other predefined +operations are allowed, and whether the first subtype is static. See 7.3.1. + +11 + +12 + +13 + +14 + +15/3 + +For a private extension, the characteristics (including components, but excluding discriminants if there is a +new discriminant_part specified), predefined operators, and inherited user-defined primitive subprograms +are determined by its ancestor type and its progenitor types (if any), in the same way that those of a record +extension are determined by those of its parent type and its progenitor types (see 3.4 and 7.3.1). + +16/3 + +The elaboration of a private_type_declaration creates a partial view of a type. The elaboration of a +private_extension_declaration elaborates the ancestor_subtype_indication, and creates a partial view of a +type. + +17 + +Dynamic Semantics + +NOTES +5 The partial view of a type as declared by a private_type_declaration is defined to be a composite view (in 3.2). The full +view of the type might or might not be composite. A private extension is also composite, as is its full view. + +6 Declaring a private type with an unknown_discriminant_part is a way of preventing clients from creating uninitialized +objects of the type; they are then forced to initialize each object by calling some operation declared in the visible part of +the package. + +7 The ancestor type specified in a private_extension_declaration and the parent type specified in the corresponding +declaration of a record extension given in the private part need not be the same. If the ancestor type is not an interface +type, the parent type of the full view can be any descendant of the ancestor type. In this case, for a primitive subprogram +that is inherited from the ancestor type and not overridden, the formal parameter names and default expressions (if any) +come from the corresponding primitive subprogram of the specified ancestor type, while the body comes from the +corresponding primitive subprogram of the parent type of the full view. See 3.9.2. + +the + +full view + +8 If the ancestor type specified in a private_extension_declaration is an interface type, the parent type can be any type so +long as +in a +the ancestor +private_extension_declaration and the progenitor types specified in the corresponding declaration of a record extension +given in the private part need not be the same — the only requirement is that the private extension and the record +extension be descended from the same set of interfaces. + +type. The progenitor + +is a descendant of + +types specified + +18 + +19/2 + +20/2 + +20.1/2 + +177 13 December 2012 + +Private Types and Private Extensions 7.3 + + 21 + +22 + +23 + +24 + +1 + +2 + +3/3 + +4/1 + +5/1 + +5.1/3 + +5.2/3 + +Ada Reference Manual — 2012 Edition + +Examples + +Examples of private type declarations: +type Key is private; +type File_Name is limited private; + +Example of a private extension declaration: + +type List is new Ada.Finalization.Controlled with private; + +7.3.1 Private Operations + +For a type declared in the visible part of a package or generic package, certain operations on the type do +not become visible until later in the package — either in the private part or the body. Such private +operations are available only inside the declarative region of the package or generic package. + +Static Semantics + +The predefined operators that exist for a given type are determined by the classes to which the type +belongs. For example, an integer type has a predefined "+" operator. In most cases, the predefined +operators of a type are declared immediately after the definition of the type; the exceptions are explained +below. Inherited subprograms are also implicitly declared immediately after the definition of the type, +except as stated below. + +For a composite type, the characteristics (see 7.3) of the type are determined in part by the characteristics +of its component types. At the place where the composite type is declared, the only characteristics of +component types used are those characteristics visible at that place. If later immediately within the +declarative region in which the composite type is declared additional characteristics become visible for a +component type, then any corresponding characteristics become visible for the composite type. Any +additional predefined operators are implicitly declared at that place. If there is no such place, then +additional predefined operators are not declared at all, but they still exist. + +The corresponding rule applies to a type defined by a derived_type_definition, if there is a place +immediately within the declarative region in which the type is declared where additional characteristics of +its parent type become visible. + +For example, an array type whose component type is limited private becomes nonlimited if the full view of +the component type is nonlimited and visible at some later place immediately within the declarative region +in which the array type is declared. In such a case, the predefined "=" operator is implicitly declared at that +place, and assignment is allowed after that place. + +A type is a descendant of the full view of some ancestor of its parent type only if the current view it has of +its parent is a descendant of the full view of that ancestor. More generally, at any given place, a type is +descended from the same view of an ancestor as that from which the current view of its parent is +descended. This view determines what characteristics are inherited from the ancestor, and, for example, +whether the type is considered to be a descendant of a record type, or a descendant only through record +extensions of a more distant ancestor. + +It is possible for there to be places where a derived type is visibly a descendant of an ancestor type, but not +a descendant of even a partial view of the ancestor type, because the parent of the derived type is not +visibly a descendant of the ancestor. In this case, the derived type inherits no characteristics from that +ancestor, but nevertheless is within the derivation class of the ancestor for the purposes of type conversion, +the "covers" relationship, and matching against a formal derived type. In this case the derived type is +considered to be a descendant of an incomplete view of the ancestor. + +7.3 Private Types and Private Extensions + +13 December 2012 178 + + Ada Reference Manual — 2012 Edition + +Inherited primitive subprograms follow a different rule. For a derived_type_definition, each inherited +primitive subprogram is implicitly declared at the earliest place, if any, immediately within the declarative +region in which the type_declaration occurs, but after the type_declaration, where the corresponding +declaration from the parent is visible. If there is no such place, then the inherited subprogram is not +declared at all, but it still exists. For a tagged type, it is possible to dispatch to an inherited subprogram +that is not declared at all. + +For a private_extension_declaration, each inherited subprogram is declared immediately after the +private_extension_declaration if the corresponding declaration from the ancestor is visible at that place. +Otherwise, the inherited subprogram is not declared for the private extension, though it might be for the +full type. + +The Class attribute is defined for tagged subtypes in 3.9. In addition, for every subtype S of an untagged +private type whose full view is tagged, the following attribute is defined: + +S'Class + +Denotes the class-wide subtype corresponding to the full view of S. This attribute is +allowed only from the beginning of the private part in which the full view is declared, until +the declaration of the full view. After the full view, the Class attribute of the full view can +be used. + +NOTES +9 Because a partial view and a full view are two different views of one and the same type, outside of the defining package +the characteristics of the type are those defined by the visible part. Within these outside program units the type is just a +private type or private extension, and any language rule that applies only to another class of types does not apply. The fact +that the full declaration might implement a private type with a type of a particular class (for example, as an array type) is +relevant only within the declarative region of the package itself including any child units. + +The consequences of this actual implementation are, however, valid everywhere. For example: any default initialization of +components takes place; the attribute Size provides the size of the full view; finalization is still done for controlled +components of the full view; task dependence rules still apply to components that are task objects. + +6/3 + +7 + +8 + +9 + +10 + +11 + +10 Partial views provide initialization, membership tests, selected components for the selection of discriminants and +inherited components, qualification, and explicit conversion. Nonlimited partial views also allow use of +assignment_statements. + +12/2 + +11 For a subtype S of a partial view, S'Size is defined (see 13.3). For an object A of a partial view, the attributes A'Size +and A'Address are defined (see 13.3). The Position, First_Bit, and Last_Bit attributes are also defined for discriminants +and inherited components. + +Example of a type with private operations: + +Examples + +package Key_Manager is + type Key is private; + Null_Key : constant Key; -- a deferred constant declaration (see 7.4) + procedure Get_Key(K : out Key); + function "<" (X, Y : Key) return Boolean; +private + type Key is new Natural; + Null_Key : constant Key := Key'First; +end Key_Manager; + +13 + +14 + +15 + +179 13 December 2012 + +Private Operations 7.3.1 + + Ada Reference Manual — 2012 Edition + +package body Key_Manager is + Last_Key : Key := Null_Key; + procedure Get_Key(K : out Key) is + begin + Last_Key := Last_Key + 1; + K := Last_Key; + end Get_Key; + function "<" (X, Y : Key) return Boolean is + begin + return Natural(X) < Natural(Y); + end "<"; +end Key_Manager; + +NOTES +12 Notes on the example: Outside of the package Key_Manager, the operations available for objects of type Key include +assignment, the comparison for equality or inequality, the procedure Get_Key and the operator "<"; they do not include +other relational operators such as ">=", or arithmetic operators. + +The explicitly declared operator "<" hides the predefined operator "<" implicitly declared by the full_type_declaration. +Within the body of the function, an explicit conversion of X and Y to the subtype Natural is necessary to invoke the "<" +operator of the parent type. Alternatively, the result of the function could be written as not (X >= Y), since the operator +">=" is not redefined. + +The value of the variable Last_Key, declared in the package body, remains unchanged between calls of the procedure +Get_Key. (See also the NOTES of 7.2.) + +16 + +17 + +18 + +19 + +20 + +7.3.2 Type Invariants + +1/3 + +For a private type or private extension, the following language-defined aspects may be specified with an +aspect_specification (see 13.1.1): + +2/3 + +Type_Invariant + +This aspect shall be specified by an expression, called an invariant expression. +Type_Invariant may be specified on a private_type_declaration, on a private_extension_- +declaration, or on a full_type_declaration that declares the completion of a private type or +private extension. + +3/3 + +Type_Invariant'Class + +This aspect shall be specified by an expression, called an invariant expression. +Type_Invariant'Class may be specified on a private_type_declaration or a private_- +extension_declaration. + +4/3 + +5/3 + +The expected type for an invariant expression is any boolean type. + +Name Resolution Rules + +Within an invariant expression, the identifier of the first subtype of the associated type denotes the current +instance of the type. Within an invariant expression associated with type T, the type of the current instance +is T for the Type_Invariant aspect and T'Class for the Type_Invariant'Class aspect. + +6/3 + +The Type_Invariant'Class aspect shall not be specified for an untagged type. The Type_Invariant aspect +shall not be specified for an abstract type. + +Legality Rules + +7/3 + +8/3 + +If the Type_Invariant aspect is specified for a type T, then the invariant expression applies to T. + +If the Type_Invariant'Class aspect is specified for a tagged type T, then the invariant expression applies to +all descendants of T. + +Static Semantics + +7.3.1 Private Operations + +13 December 2012 180 + + + + Ada Reference Manual — 2012 Edition + +Dynamic Semantics + +If one or more invariant expressions apply to a type T, then an invariant check is performed at the +following places, on the specified object(s): + +• After successful default initialization of an object of type T, the check is performed on the new + +object; + +• After successful conversion to type T, the check is performed on the result of the conversion; +• For a view conversion, outside the immediate scope of T, that converts from a descendant of T +(including T itself) to an ancestor of type T (other than T itself), a check is performed on the part +of the object that is of type T: + +• after assigning to the view conversion; and + +• after successful return from a call that passes the view conversion as an in out or out + +parameter. + +• After a successful call on the Read or Input stream attribute of the type T, the check is performed + +on the object initialized by the stream attribute; + +• An invariant is checked upon successful return from a call on any subprogram or entry that: + +• + +• + +is declared within the immediate scope of type T (or by an instance of a generic unit, and +the generic is declared within the immediate scope of type T), and + +is visible outside the immediate scope of type T or overrides an operation that is visible +outside the immediate scope of T, and + +• has a result with a part of type T, or one or more parameters with a part of type T, or an + +access to variable parameter whose designated type has a part of type T. + + The check is performed on each such part of type T. + +If performing checks is required by the Invariant or Invariant'Class assertion policies (see 11.4.2) in effect +at the point of corresponding aspect specification applicable to a given type, then the respective invariant +expression is considered enabled. + +The invariant check consists of the evaluation of each enabled invariant expression that applies to T, on +each of the objects specified above. If any of these evaluate to False, Assertions.Assertion_Error is raised +at the point of the object initialization, conversion, or call. If a given call requires more than one +evaluation of an invariant expression, either for multiple objects of a single type or for multiple types with +invariants, the evaluations are performed in an arbitrary order, and if one of them evaluates to False, it is +not specified whether the others are evaluated. Any invariant check is performed prior to copying back any +by-copy in out or out parameters. Invariant checks, any postcondition check, and any constraint or +predicate checks associated with in out or out parameters are performed in an arbitrary order. + +9/3 + +10/3 + +11/3 + +12/3 + +13/3 + +14/3 + +15/3 + +16/3 + +17/3 + +18/3 + +19/3 + +20/3 + +21/3 + +22/3 + +The invariant checks performed on a call are determined by the subprogram or entry actually invoked, +whether directly, as part of a dispatching call, or as part of a call through an access-to-subprogram value. + +23/3 + +NOTES +13 For a call of a primitive subprogram of type NT that is inherited from type T, the specified checks of the specific +invariants of both the types NT and T are performed. For a call of a primitive subprogram of type NT that is overridden for +type NT, the specified checks of the specific invariants of only type NT are performed. + +24/3 + +181 13 December 2012 + +Type Invariants 7.3.2 + + Ada Reference Manual — 2012 Edition + +7.4 Deferred Constants + +1 + +2/3 + +3 + +4 + +5/2 + +6/3 + +Deferred constant declarations may be used to declare constants in the visible part of a package, but with +the value of the constant given in the private part. They may also be used to declare constants imported +from other languages (see Annex B). + +Legality Rules + +A deferred constant declaration is an object_declaration with the reserved word constant but no +initialization expression. The constant declared by a deferred constant declaration is called a deferred +constant. Unless the Import aspect (see B.1) is True for a deferred constant declaration, the deferred +constant declaration requires a completion, which shall be a full constant declaration (called the full +declaration of the deferred constant). + +A deferred constant declaration that is completed by a full constant declaration shall occur immediately +within the visible part of a package_specification. For this case, the following additional rules apply to +the corresponding full declaration: + +• The full declaration shall occur immediately within the private part of the same package; +• The deferred and full constants shall have the same type, or shall have statically matching + +anonymous access subtypes; + +• If the deferred constant declaration includes a subtype_indication S that defines a constrained +subtype, then the constraint defined by the subtype_indication in the full declaration shall match +the constraint defined by S statically. On the other hand, if the subtype of the deferred constant is +unconstrained, then the full declaration is still allowed to impose a constraint. The constant itself +will be constrained, like all constants; + +7/2 + +• If the deferred constant declaration includes the reserved word aliased, then the full declaration + +shall also; + +7.1/2 + +• If the subtype of the deferred constant declaration excludes null, the subtype of the full + +declaration shall also exclude null. + +8/3 + +A deferred constant declaration for which the Import aspect is True need not appear in the visible part of a +package_specification, and has no full constant declaration. + +9/2 + +The completion of a deferred constant declaration shall occur before the constant is frozen (see 13.14). + +10/3 + +The elaboration of a deferred constant declaration elaborates the subtype_indication, access_definition, +or (only allowed in the case of an imported constant) the array_type_definition. + +Dynamic Semantics + +11 + +12 + +13 + +14/3 + +NOTES +14 The full constant declaration for a deferred constant that is of a given private type or private extension is not allowed +before the corresponding full_type_declaration. This is a consequence of the freezing rules for types (see 13.14). + +Examples of deferred constant declarations: + +Examples + +Null_Key : constant Key; -- see 7.3.1 +CPU_Identifier : constant String(1..8) + with Import => True, Convention => Assembler, Link_Name => "CPU_ID"; + -- see B.1 + +7.4 Deferred Constants + +13 December 2012 182 + + Ada Reference Manual — 2012 Edition + +7.5 Limited Types + +A limited type is (a view of) a type for which copying (such as for an assignment_statement) is not +allowed. A nonlimited type is a (view of a) type for which copying is allowed. + +1/2 + +Legality Rules + +If a tagged record type has any limited components, then the reserved word limited shall appear in its +record_type_definition. +a +derived_type_definition, its parent type and any progenitor interfaces shall be limited. + +the definition of + +reserved word + +appears + +limited + +the + +in + +If + +In the following contexts, an expression of a limited type is not permitted unless it is an aggregate, a +function_call, a parenthesized expression or qualified_expression whose operand is permitted by this +rule, or a conditional_expression all of whose dependent_expressions are permitted by this rule: + +the initialization expression of an object_declaration (see 3.3.1) + +the default_expression of a component_declaration (see 3.8) + +the expression of a record_component_association (see 4.3.1) + +the expression for an ancestor_part of an extension_aggregate (see 4.3.2) + +• +• +• +• +• an + +expression + +of +array_component_association (see 4.3.3) + +a + +positional_array_aggregate + +or + +the + +expression + +of + +an + +• +• +• +• + +the qualified_expression of an initialized allocator (see 4.8) + +the expression of a return statement (see 6.5) + +the expression of an expression_function_declaration (see 6.8) + +the default_expression or actual parameter for a formal object of mode in (see 12.4) + +A view of a type is limited if it is one of the following: + +Static Semantics + +• a type with the reserved word limited, synchronized, task, or protected in its definition; +• a class-wide type whose specific type is limited; +• a composite type with a limited component; +• an incomplete view; +• a derived type whose parent is limited and is not an interface. + +Otherwise, the type is nonlimited. + +There are no predefined equality operators for a limited type. + +A type is immutably limited if it is one of the following: + +• An explicitly limited record type; +• A record extension with the reserved word limited; +• A nonformal limited private type that is tagged or has at least one access discriminant with a + +default_expression; + +• A task type, a protected type, or a synchronized interface; +• A type derived from an immutably limited type. + +183 13 December 2012 + +Limited Types 7.5 + +2/2 + +2.1/3 + +2.2/2 + +2.3/2 + +2.4/2 + +2.5/2 + +2.6/2 + +2.7/2 + +2.8/2 + +2.9/3 + +2.10/3 + +3/3 + +4/2 + +5/3 + +6/2 + +6.1/3 + +6.2/2 + +7 + +8 + +8.1/3 + +8.2/3 + +8.3/3 + +8.4/3 + +8.5/3 + +8.6/3 + + Ada Reference Manual — 2012 Edition + +8.7/3 + +A descendant of a generic formal limited private type is presumed to be immutably limited except within +the body of a generic unit or a body declared within the declarative region of a generic unit, if the formal +type is declared within the formal part of the generic unit. + +9/3 + +16 + +17 + +18 + +19 + +20 + +21 + +22 + +NOTES +15 While it is allowed to write initializations of limited objects, such initializations never copy a limited object. The +source of such an assignment operation must be an aggregate or function_call, and such aggregates and function_calls +must be built directly in the target object (see 7.6). + +Paragraphs 10 through 15 were deleted. + +16 As illustrated in 7.3.1, an untagged limited type can become nonlimited under certain circumstances. + +Example of a package with a limited type: + +Examples + +package IO_Package is + type File_Name is limited private; + procedure Open (F : in out File_Name); + procedure Close(F : in out File_Name); + procedure Read (F : in File_Name; Item : out Integer); + procedure Write(F : in File_Name; Item : in Integer); +private + type File_Name is + limited record + Internal_Name : Integer := 0; + end record; +end IO_Package; +package body IO_Package is + Limit : constant := 200; + type File_Descriptor is record ... end record; + Directory : array (1 .. Limit) of File_Descriptor; + ... + procedure Open (F : in out File_Name) is ... end; + procedure Close(F : in out File_Name) is ... end; + procedure Read (F : in File_Name; Item : out Integer) is ... end; + procedure Write(F : in File_Name; Item : in Integer) is ... end; +begin + ... +end IO_Package; + +NOTES +17 Notes on the example: In the example above, an outside subprogram making use of IO_Package may obtain a file +name by calling Open and later use it in calls to Read and Write. Thus, outside the package, a file name obtained from +Open acts as a kind of password; its internal properties (such as containing a numeric value) are not known and no other +operations (such as addition or comparison of internal names) can be performed on a file name. Most importantly, clients +of the package cannot make copies of objects of type File_Name. + +This example is characteristic of any case where complete control over the operations of a type is desired. Such packages +serve a dual purpose. They prevent a user from making use of the internal structure of the type. They also implement the +notion of an encapsulated data type where the only operations on the type are those given in the package specification. + +23/2 + +The fact that the full view of File_Name is explicitly declared limited means that parameter passing will always be by +reference and function results will always be built directly in the result object (see 6.2 and 6.5). + +7.5 Limited Types + +13 December 2012 184 + + Ada Reference Manual — 2012 Edition + +7.6 Assignment and Finalization + +Three kinds of actions are fundamental to the manipulation of objects: initialization, finalization, and +assignment. Every object is initialized, either explicitly or by default, after being created (for example, by +an object_declaration or allocator). Every object is finalized before being destroyed (for example, by +leaving a subprogram_body containing an object_declaration, or by a call to an instance of +Unchecked_Deallocation). An assignment operation is used as part of assignment_statements, explicit +initialization, parameter passing, and other operations. + +Default definitions for these three fundamental operations are provided by the language, but a controlled +type gives the user additional control over parts of these operations. In particular, the user can define, for a +controlled type, an Initialize procedure which is invoked immediately after the normal default +initialization of a controlled object, a Finalize procedure which is invoked immediately before finalization +of any of the components of a controlled object, and an Adjust procedure which is invoked as the last step +of an assignment to a (nonlimited) controlled object. + +The following language-defined library package exists: + +Static Semantics + +package Ada.Finalization is + pragma Pure(Finalization); + type Controlled is abstract tagged private; + pragma Preelaborable_Initialization(Controlled); + procedure Initialize (Object : in out Controlled) is null; + procedure Adjust (Object : in out Controlled) is null; + procedure Finalize (Object : in out Controlled) is null; + type Limited_Controlled is abstract tagged limited private; + pragma Preelaborable_Initialization(Limited_Controlled); + procedure Initialize (Object : in out Limited_Controlled) is null; + procedure Finalize (Object : in out Limited_Controlled) is null; +private + ... -- not specified by the language +end Ada.Finalization; + +A controlled type is a descendant of Controlled or Limited_Controlled. The predefined "=" operator of +type Controlled always returns True, since this operator is incorporated into the implementation of the +predefined equality operator of types derived from Controlled, as explained in 4.5.2. The type +Limited_Controlled is like Controlled, except that it is limited and it lacks the primitive subprogram +Adjust. + +A type is said to need finalization if: + +• +• +• +• +• + +it is a controlled type, a task type or a protected type; or + +it has a component whose type needs finalization; or + +it is a class-wide type; or + +it is a partial view whose full view needs finalization; or + +it is one of a number of language-defined types that are explicitly defined to need finalization. + +1 + +2 + +3 + +4/3 + +5/2 + +6/2 + +7/2 + +8/2 + +9/2 + +9.1/2 + +9.2/2 + +9.3/3 + +9.4/3 + +9.5/3 + +9.6/2 + +During the elaboration or evaluation of a construct that causes an object to be initialized by default, for +every controlled subcomponent of the object that is not assigned an initial value (as defined in 3.3.1), + +10/2 + +Dynamic Semantics + +185 13 December 2012 + +Assignment and Finalization 7.6 + + Ada Reference Manual — 2012 Edition + +11/2 + +12 + +13 + +14 + +15 + +16/3 + +17 + +Initialize is called on that subcomponent. Similarly, if the object that is initialized by default as a whole is +controlled, Initialize is called on the object. + +For an extension_aggregate whose ancestor_part is a subtype_mark denoting a controlled subtype, the +Initialize procedure of the ancestor type is called, unless that Initialize procedure is abstract. + +Initialize and other initialization operations are done in an arbitrary order, except as follows. Initialize is +applied to an object after initialization of its subcomponents, if any (including both implicit initialization +and Initialize calls). If an object has a component with an access discriminant constrained by a per-object +expression, Initialize is applied to this component after any components that do not have such +discriminants. For an object with several components with such a discriminant, Initialize is applied to them +in order of their component_declarations. For an allocator, any task activations follow all calls on +Initialize. + +When a target object with any controlled parts is assigned a value, either when created or in a subsequent +assignment_statement, the assignment operation proceeds as follows: + +• The value of the target becomes the assigned value. +• The value of the target is adjusted. + +To adjust the value of a composite object, the values of the components of the object are first adjusted in +an arbitrary order, and then, if the object is nonlimited controlled, Adjust is called. Adjusting the value of +an elementary object has no effect, nor does adjusting the value of a composite object with no controlled +parts. + +For an assignment_statement, after the name and expression have been evaluated, and any conversion +(including constraint checking) has been done, an anonymous object is created, and the value is assigned +into it; that is, the assignment operation is applied. (Assignment includes value adjustment.) The target of +the assignment_statement is then finalized. The value of the anonymous object is then assigned into the +target of the assignment_statement. Finally, the anonymous object is finalized. As explained below, the +implementation may eliminate the intermediate anonymous object, so this description subsumes the one +given in 5.2, “Assignment Statements”. + +17.1/3 + +When a function call or aggregate is used to initialize an object, the result of the function call or +aggregate is an anonymous object, which is assigned into the newly-created object. For such an +assignment, the anonymous object might be built in place, in which case the assignment does not involve +any copying. Under certain circumstances, the anonymous object is required to be built in place. In +particular: + +17.2/3 + +• If the full type of any part of the object is immutably limited, the anonymous object is built in + +place. + +17.3/3 + +• In the case of an aggregate, if the full type of any part of the newly-created object is controlled, + +the anonymous object is built in place. + +17.4/3 + +• In other cases, it is unspecified whether the anonymous object is built in place. + +17.5/3 + +Notwithstanding what this International Standard says elsewhere, if an object is built in place: + +17.6/3 + +• Upon successful completion of the return statement or aggregate, the anonymous object mutates +into the newly-created object; that is, the anonymous object ceases to exist, and the newly- +created object appears in its place. + +17.7/3 + +17.8/3 + +• Finalization is not performed on the anonymous object. +• Adjustment is not performed on the newly-created object. + +7.6 Assignment and Finalization + +13 December 2012 186 + + Ada Reference Manual — 2012 Edition + +• All access values that designate parts of the anonymous object now designate the corresponding + +17.9/3 + +parts of the newly-created object. + +• All renamings of parts of the anonymous object now denote views of the corresponding parts of + +17.10/3 + +the newly-created object. + +• Coextensions of the anonymous object become coextensions of the newly-created object. + +17.11/3 + +An implementation is allowed to relax the above rules for assignment_statements in the following ways: + +18/3 + +Implementation Permissions + +• If an object is assigned the value of that same object, the implementation need not do anything. +• For assignment of a noncontrolled type, the implementation may finalize and assign each +component of the variable separately (rather than finalizing the entire variable and assigning the +entire new value) unless a discriminant of the variable is changed by the assignment. + +• The implementation need not create an anonymous object if the value being assigned is the +result of evaluating a name denoting an object (the source object) whose storage cannot overlap +with the target. If the source object might overlap with the target object, then the implementation +can avoid the need for an intermediary anonymous object by exercising one of the above +permissions and perform the assignment one component at a time (for an overlapping array +assignment), or not at all (for an assignment where the target and the source of the assignment +are the same object). + +Furthermore, an implementation is permitted to omit implicit Initialize, Adjust, and Finalize calls and +associated assignment operations on an object of a nonlimited controlled type provided that: + +• any omitted Initialize call is not a call on a user-defined Initialize procedure, and +• any usage of the value of the object after the implicit Initialize or Adjust call and before any +subsequent Finalize call on the object does not change the external effect of the program, and +• after the omission of such calls and operations, any execution of the program that executes an +Initialize or Adjust call on an object or initializes an object by an aggregate will also later +execute a Finalize call on the object and will always do so prior to assigning a new value to the +object, and + +• + +the assignment operations associated with omitted Adjust calls are also omitted. + +This permission applies to Adjust and Finalize calls even if the implicit calls have additional external +effects. + +7.6.1 Completion and Finalization + +This subclause defines completion and leaving of the execution of constructs and entities. A master is the +execution of a construct that includes finalization of local objects after it is complete (and after waiting for +any local tasks — see 9.3), but before leaving. Other constructs and entities are left immediately upon +completion. + +Dynamic Semantics + +The execution of a construct or entity is complete when the end of that execution has been reached, or +when a transfer of control (see 5.1) causes it to be abandoned. Completion due to reaching the end of +execution, or due to the transfer of control of an exit_statement, return statement, goto_statement, or +requeue_statement or of the selection of a terminate_alternative is normal completion. Completion is +abnormal otherwise — when control is transferred out of a construct due to abort or the raising of an +exception. + +19/3 + +20/3 + +21/3 + +22/2 + +23/2 + +24/2 + +25/2 + +26/2 + +27/2 + +1 + +2/2 + +187 13 December 2012 + +Assignment and Finalization 7.6 + + Ada Reference Manual — 2012 Edition + +3/2 + +4 + +5 + +6/3 + +7/3 + +8/3 + +9/3 + +After execution of a construct or entity is complete, it is left, meaning that execution continues with the +next action, as defined for the execution that is taking place. Leaving an execution happens immediately +after its completion, except in the case of a master: the execution of a body other than a package_body; +the execution of a statement; or the evaluation of an expression, function_call, or range that is not part of +an enclosing expression, function_call, range, or simple_statement other than a simple_return_- +statement. A master is finalized after it is complete, and before it is left. + +For the finalization of a master, dependent tasks are first awaited, as explained in 9.3. Then each object +whose accessibility level is the same as that of the master is finalized if the object was successfully +initialized and still exists. These actions are performed whether the master is left by reaching the last +statement or via a transfer of control. When a transfer of control causes completion of an execution, each +included master is finalized in order, from innermost outward. + +For the finalization of an object: + +• If the full type of the object is an elementary type, finalization has no effect; +• If the full type of the object is a tagged type, and the tag of the object identifies a controlled + +type, the Finalize procedure of that controlled type is called; + +• If the full type of the object is a protected type, or if the full type of the object is a tagged type +and the tag of the object identifies a protected type, the actions defined in 9.4 are performed; +• If the full type of the object is a composite type, then after performing the above actions, if any, +every component of the object is finalized in an arbitrary order, except as follows: if the object +has a component with an access discriminant constrained by a per-object expression, this +component is finalized before any components that do not have such discriminants; for an object +with several components with such a discriminant, they are finalized in the reverse of the order +of their component_declarations; + +9.1/2 + +• If the object has coextensions (see 3.10.2), each coextension is finalized after the object whose + +access discriminant designates it. + +10 + +11/3 + +11.1/3 + +11.2/3 + +11.3/3 + +11.4/3 + +11.5/3 + +Immediately before an instance of Unchecked_Deallocation reclaims the storage of an object, the object is +finalized. If an instance of Unchecked_Deallocation is never applied to an object created by an allocator, +the object will still exist when the corresponding master completes, and it will be finalized then. + +The finalization of a master performs finalization of objects created by declarations in the master in the +reverse order of their creation. After the finalization of a master is complete, the objects finalized as part of +its finalization cease to exist, as do any types and subtypes defined and created within the master. + +Each nonderived access type T has an associated collection, which is the set of objects created by +allocators of T, or of types derived from T. Unchecked_Deallocation removes an object from its collection. +Finalization of a collection consists of finalization of each object in the collection, in an arbitrary order. +The collection of an access type is an object implicitly declared at the following place: + +• For a named access type, the first freezing point (see 13.14) of the type. +• For the type of an access parameter, the call that contains the allocator. +• For the type of an access result, within the master of the call (see 3.10.2). +• For any other anonymous access type, the first freezing point of the innermost enclosing + +declaration. + +12/2 + +The target of an assignment_statement is finalized before copying in the new value, as explained in 7.6. + +13/3 + +The master of an object is the master enclosing its creation whose accessibility level (see 3.10.2) is equal +to that of the object, except in the case of an anonymous object representing the result of an aggregate or + +7.6.1 Completion and Finalization + +13 December 2012 188 + + Ada Reference Manual — 2012 Edition + +function call. If such an anonymous object is part of the result of evaluating the actual parameter +expression for an explicitly aliased parameter of a function call, the master of the object is the innermost +master enclosing the evaluation of the aggregate or function call, excluding the aggregate or function call +itself. Otherwise, the master of such an anonymous object is the innermost master enclosing the evaluation +of the aggregate or function call, which may be the aggregate or function call itself. + +In the case of an expression that is a master, finalization of any (anonymous) objects occurs after +completing evaluation of the expression and all use of the objects, prior to starting the execution of any +subsequent construct. + +13.1/3 + +Bounded (Run-Time) Errors + +It is a bounded error for a call on Finalize or Adjust that occurs as part of object finalization or assignment +to propagate an exception. The possible consequences depend on what action invoked the Finalize or +Adjust operation: + +• For a Finalize invoked as part of an assignment_statement, Program_Error is raised at that + +point. + +• For an Adjust invoked as part of assignment operations other than those invoked as part of an +assignment_statement, other adjustments due to be performed might or might not be +performed, and then Program_Error is raised. During its propagation, finalization might or might +not be applied to objects whose Adjust failed. For an Adjust invoked as part of an +assignment_statement, any other adjustments due to be performed are performed, and then +Program_Error is raised. + +14/1 + +15 + +16/2 + +• For a Finalize invoked as part of a call on an instance of Unchecked_Deallocation, any other + +17 + +finalizations due to be performed are performed, and then Program_Error is raised. + +• This paragraph was deleted. +• For a Finalize invoked due to reaching the end of the execution of a master, any other +finalizations associated with the master are performed, and Program_Error is raised immediately +after leaving the master. + +• For a Finalize invoked by the transfer of control of an exit_statement, return statement, +goto_statement, or requeue_statement, Program_Error is raised no earlier than after the +finalization of the master being finalized when the exception occurred, and no later than the +point where normal execution would have continued. Any other finalizations due to be +performed up to that point are performed before raising Program_Error. + +• For a Finalize invoked by a transfer of control that is due to raising an exception, any other +finalizations due to be performed for the same master are performed; Program_Error is raised +immediately after leaving the master. + +• For a Finalize invoked by a transfer of control due to an abort or selection of a terminate +alternative, the exception is ignored; any other finalizations due to be performed are performed. + +Implementation Permissions + +If the execution of an allocator propagates an exception, any parts of the allocated object that were +successfully initialized may be finalized as part of the finalization of the innermost master enclosing the +allocator. + +The implementation may finalize objects created by allocators for an access type whose storage pool +supports subpools (see 13.11.4) as if the objects were created (in an arbitrary order) at the point where the +storage pool was elaborated instead of at the first freezing point of the access type. + +17.1/3 + +17.2/1 + +18/2 + +19 + +20 + +20.1/3 + +20.2/3 + +189 13 December 2012 + +Completion and Finalization 7.6.1 + + Ada Reference Manual — 2012 Edition + +21/3 + +22 + +23 + +24 + +NOTES +18 The rules of Clause 10 imply that immediately prior to partition termination, Finalize operations are applied to library- +level controlled objects (including those created by allocators of library-level access types, except those already finalized). +This occurs after waiting for library-level tasks to terminate. + +19 A constant is only constant between its initialization and finalization. Both initialization and finalization are allowed to +change the value of a constant. + +20 Abort is deferred during certain operations related to controlled types, as explained in 9.8. Those rules prevent an +abort from causing a controlled object to be left in an ill-defined state. + +21 The Finalize procedure is called upon finalization of a controlled object, even if Finalize was called earlier, either +explicitly or as part of an assignment; hence, if a controlled type is visibly controlled (implying that its Finalize primitive +is directly callable), or is nonlimited (implying that assignment is allowed), its Finalize procedure should be designed to +have no ill effect if it is applied a second time to the same object. + +7.6.1 Completion and Finalization + +13 December 2012 190 + + Ada Reference Manual — 2012 Edition + +8 Visibility Rules + +The rules defining the scope of declarations and the rules defining which identifiers, character_literals, +and operator_symbols are visible at (or from) various places in the text of the program are described in +this clause. The formulation of these rules uses the notion of a declarative region. + +As explained in Clause 3, a declaration declares a view of an entity and associates a defining name with +that view. The view comprises an identification of the viewed entity, and possibly additional properties. A +usage name denotes a declaration. It also denotes the view declared by that declaration, and denotes the +entity of that view. Thus, two different usage names might denote two different views of the same entity; +in this case they denote the same entity. + +8.1 Declarative Region + +For each of the following constructs, there is a portion of the program text called its declarative region, +within which nested declarations can occur: + +• any declaration, other than that of an enumeration type, that is not a completion of a previous + +Static Semantics + +declaration; + +• a block_statement; +• a loop_statement; +• a quantified_expression; +• an extended_return_statement; +• an accept_statement; +• an exception_handler. + +The declarative region includes the text of the construct together with additional text determined +(recursively), as follows: + +• If a declaration is included, so is its completion, if any. +• If the declaration of a library unit (including Standard — see 10.1.1) is included, so are the +declarations of any child units (and their completions, by the previous rule). The child +declarations occur after the declaration. + +• If a body_stub is included, so is the corresponding subunit. +• If a type_declaration is included, then so is a corresponding record_representation_clause, if + +any. + +The declarative region of a declaration is also called the declarative region of any view or entity declared +by the declaration. + +A declaration occurs immediately within a declarative region if this region is the innermost declarative +region that encloses the declaration (the immediately enclosing declarative region), not counting the +declarative region (if any) associated with the declaration itself. + +A declaration is local to a declarative region if the declaration occurs immediately within the declarative +region. An entity is local to a declarative region if the entity is declared by a declaration that is local to the +declarative region. + +191 13 December 2012 + +Visibility Rules 8 + +1/3 + +2/3 + +1 + +2 + +3 + +4 + +4.1/3 + +4.2/3 + +5 + +6 + +7 + +8 + +9 + +10 + +11 + +12 + +13 + +14 + + Ada Reference Manual — 2012 Edition + +15 + +16 + +17 + +18 + +1 + +2 + +3 + +4 + +5 + +6 + +7 + +8 + +9 + +A declaration is global to a declarative region if the declaration occurs immediately within another +declarative region that encloses the declarative region. An entity is global to a declarative region if the +entity is declared by a declaration that is global to the declarative region. + +NOTES +1 The children of a parent library unit are inside the parent's declarative region, even though they do not occur inside the +parent's declaration or body. This implies that one can use (for example) "P.Q" to refer to a child of P whose defining +name is Q, and that after "use P;" Q can refer (directly) to that child. + +2 As explained above and in 10.1.1, “Compilation Units - Library Units”, all library units are descendants of Standard, +and so are contained in the declarative region of Standard. They are not inside the declaration or body of Standard, but +they are inside its declarative region. + +3 For a declarative region that comes in multiple parts, the text of the declarative region does not contain any text that +might appear between the parts. Thus, when a portion of a declarative region is said to extend from one place to another in +the declarative region, the portion does not contain any text that might appear between the parts of the declarative region. + +8.2 Scope of Declarations + +For each declaration, the language rules define a certain portion of the program text called the scope of the +declaration. The scope of a declaration is also called the scope of any view or entity declared by the +declaration. Within the scope of an entity, and only there, there are places where it is legal to refer to the +declared entity. These places are defined by the rules of visibility and overloading. + +Static Semantics + +The immediate scope of a declaration is a portion of the declarative region immediately enclosing the +declaration. The immediate scope starts at the beginning of the declaration, except in the case of an +overloadable declaration, in which case the immediate scope starts just after the place where the profile of +the callable entity is determined (which is at the end of the _specification for the callable entity, or at the +end of the generic_instantiation if an instance). The immediate scope extends to the end of the declarative +region, with the following exceptions: + +• The immediate scope of a library_item includes only its semantic dependents. +• The immediate scope of a declaration in the private part of a library unit does not include the + +visible part of any public descendant of that library unit. + +The visible part of (a view of) an entity is a portion of the text of its declaration containing declarations +that are visible from outside. The private part of (a view of) an entity that has a visible part contains all +declarations within the declaration of (the view of) the entity, except those in the visible part; these are not +visible from outside. Visible and private parts are defined only for these kinds of entities: callable entities, +other program units, and composite types. + +• The visible part of a view of a callable entity is its profile. +• The visible part of a composite type other than a task or protected type consists of the +declarations of all components declared (explicitly or implicitly) within the type_declaration. +• The visible part of a generic unit includes the generic_formal_part. For a generic package, it +also includes the first list of basic_declarative_items of the package_specification. For a +generic subprogram, it also includes the profile. + +• The visible part of a package, task unit, or protected unit consists of declarations in the program +unit's declaration other than those following the reserved word private, if any; see 7.1 and 12.7 +for packages, 9.1 for task units, and 9.4 for protected units. + +8.1 Declarative Region + +13 December 2012 192 + + Ada Reference Manual — 2012 Edition + +The scope of a declaration always contains the immediate scope of the declaration. In addition, for a given +declaration that occurs immediately within the visible part of an outer declaration, or is a public child of an +outer declaration, the scope of the given declaration extends to the end of the scope of the outer +declaration, except that the scope of a library_item includes only its semantic dependents. + +10 + +The scope of an attribute_definition_clause is identical to the scope of a declaration that would occur at +the point of the attribute_definition_clause. The scope of an aspect_specification is identical to the scope +of the associated declaration. + +10.1/3 + +The immediate scope of a declaration is also the immediate scope of the entity or view declared by the +declaration. Similarly, the scope of a declaration is also the scope of the entity or view declared by the +declaration. + +11 + +NOTES +4 There are notations for denoting visible declarations that are not directly visible. For example, parameter_- +specifications are in the visible part of a subprogram_declaration so that they can be used in named-notation calls +appearing outside the called subprogram. For another example, declarations of the visible part of a package can be denoted +by expanded names appearing outside the package, and can be made directly visible by a use_clause. + +12/3 + +8.3 Visibility + +The visibility rules, given below, determine which declarations are visible and directly visible at each +place within a program. The visibility rules apply to both explicit and implicit declarations. + +Static Semantics + +A declaration is defined to be directly visible at places where a name consisting of only an identifier or +operator_symbol is sufficient to denote the declaration; that is, no selected_component notation or +special context (such as preceding => in a named association) is necessary to denote the declaration. A +declaration is defined to be visible wherever it is directly visible, as well as at other places where some +name (such as a selected_component) can denote the declaration. + +The syntactic category direct_name is used to indicate contexts where direct visibility is required. The +syntactic category selector_name is used to indicate contexts where visibility, but not direct visibility, is +required. + +There are two kinds of direct visibility: immediate visibility and use-visibility. A declaration is +immediately visible at a place if it is directly visible because the place is within its immediate scope. A +declaration is use-visible if it is directly visible because of a use_clause (see 8.4). Both conditions can +apply. + +A declaration can be hidden, either from direct visibility, or from all visibility, within certain parts of its +scope. Where hidden from all visibility, it is not visible at all (neither using a direct_name nor a +selector_name). Where hidden from direct visibility, only direct visibility is lost; visibility using a +selector_name is still possible. + +Two or more declarations are overloaded if they all have the same defining name and there is a place +where they are all directly visible. + +The declarations of callable entities (including enumeration literals) are overloadable, meaning that +overloading is allowed for them. + +Two declarations are homographs if they have the same defining name, and, if both are overloadable, their +profiles are type conformant. An inner declaration hides any outer homograph from direct visibility. + +1 + +2 + +3 + +4 + +5 + +6 + +7 + +8 + +193 13 December 2012 + +Scope of Declarations 8.2 + + Ada Reference Manual — 2012 Edition + +9/1 + +Two homographs are not generally allowed immediately within the same declarative region unless one +overrides the other (see Legality Rules below). The only declarations that are overridable are the implicit +declarations for predefined operators and inherited primitive subprograms. A declaration overrides another +homograph that occurs immediately within the same declarative region in the following cases: + +10/1 + +• A declaration that is not overridable overrides one that is overridable, regardless of which + +declaration occurs first; + +11 + +12 + +• The implicit declaration of an inherited operator overrides that of a predefined operator; +• An implicit declaration of an inherited subprogram overrides a previous implicit declaration of + +12.1/2 + +12.2/2 + +12.3/2 + +13 + +14 + +15 + +16 + +17 + +18/3 + +18.1/2 + +19 + +an inherited subprogram. + +• If two or more homographs are implicitly declared at the same place: + +• If at least one is a subprogram that is neither a null procedure nor an abstract subprogram, +and does not require overriding (see 3.9.3), then they override those that are null +procedures, abstract subprograms, or require overriding. If more than one such homograph +remains that is not thus overridden, then they are all hidden from all visibility. + +• Otherwise (all are null procedures, abstract subprograms, or require overriding), then any +null procedure overrides all abstract subprograms and all subprograms that require +overriding; if more than one such homograph remains that is not thus overridden, then if +they are all fully conformant with one another, one is chosen arbitrarily; if not, they are all +hidden from all visibility. + +• For an implicit declaration of a primitive subprogram in a generic unit, there is a copy of this +declaration in an instance. However, a whole new set of primitive subprograms is implicitly +declared for each type declared within the visible part of the instance. These new declarations +occur immediately after the type declaration, and override the copied ones. The copied ones can +be called only from within the instance; the new ones can be called only from outside the +instance, although for tagged types, the body of a new one can be executed by a call to an old +one. + +A declaration is visible within its scope, except where hidden from all visibility, as follows: + +• An overridden declaration is hidden from all visibility within the scope of the overriding + +declaration. + +• A declaration is hidden from all visibility until the end of the declaration, except: + +• For a record type or record extension, the declaration is hidden from all visibility only until + +the reserved word record; + +• For a package_declaration, generic_package_declaration, subprogram_body, or +expression_function_declaration, the declaration is hidden from all visibility only until the +reserved word is of the declaration; + +• For a task declaration or protected declaration, the declaration is hidden from all visibility +only until the reserved word with of the declaration if there is one, or the reserved word is +of the declaration if there is no with. + +• If the completion of a declaration is a declaration, then within the scope of the completion, the +first declaration is hidden from all visibility. Similarly, a discriminant_specification or +parameter_specification is hidden within the scope of a corresponding discriminant_- +specification or parameter_specification of a corresponding completion, or of a corresponding +accept_statement. + +20/2 + +• The declaration of a library unit (including a library_unit_renaming_declaration) is hidden from +all visibility at places outside its declarative region that are not within the scope of a +nonlimited_with_clause that mentions it. The limited view of a library package is hidden from + +8.3 Visibility + +13 December 2012 194 + + Ada Reference Manual — 2012 Edition + +all visibility at places that are not within the scope of a limited_with_clause that mentions it; in +addition, the limited view is hidden from all visibility within the declarative region of the +package, as well as within the scope of any nonlimited_with_clause that mentions the package. +Where the declaration of the limited view of a package is visible, any name that denotes the +package denotes the limited view, including those provided by a package renaming. + +• For each declaration or renaming of a generic unit as a child of some parent generic package, +there is a corresponding declaration nested immediately within each instance of the parent. Such +a nested declaration is hidden from all visibility except at places that are within the scope of a +with_clause that mentions the child. + +A declaration with a defining_identifier or defining_operator_symbol is immediately visible (and hence +directly visible) within its immediate scope except where hidden from direct visibility, as follows: + +• A declaration is hidden from direct visibility within the immediate scope of a homograph of the + +declaration, if the homograph occurs within an inner declarative region; + +• A declaration is also hidden from direct visibility where hidden from all visibility. + +20.1/2 + +21 + +22 + +23 + +An attribute_definition_clause or an aspect_specification is visible everywhere within its scope. + +23.1/3 + +Name Resolution Rules + +A direct_name shall resolve to denote a directly visible declaration whose defining name is the same as +the direct_name. A selector_name shall resolve to denote a visible declaration whose defining name is +the same as the selector_name. + +These rules on visibility and direct visibility do not apply in a context_clause, a parent_unit_name, or a +pragma that appears at the place of a compilation_unit. For those contexts, see the rules in 10.1.6, +“Environment-Level Visibility Rules”. + +Legality Rules + +A nonoverridable declaration is illegal if there is a homograph occurring immediately within the same +declarative region that is visible at the place of the declaration, and is not hidden from all visibility by the +nonoverridable declaration. In addition, a type extension is illegal if somewhere within its immediate +scope it has two visible components with the same name. Similarly, the context_clause for a compilation +unit is illegal if it mentions (in a with_clause) some library unit, and there is a homograph of the library +unit that is visible at the place of the compilation unit, and the homograph and the mentioned library unit +are both declared immediately within the same declarative region. These rules also apply to dispatching +operations declared in the visible part of an instance of a generic unit. However, they do not apply to other +overloadable declarations in an instance; such declarations may have type conformant profiles in the +instance, so long as the corresponding declarations in the generic were not type conformant. + +NOTES +5 Visibility for compilation units follows from the definition of the environment in 10.1.4, except that it is necessary to +apply a with_clause to obtain visibility to a library_unit_declaration or library_unit_renaming_declaration. + +6 In addition to the visibility rules given above, the meaning of the occurrence of a direct_name or selector_name at a +given place in the text can depend on the overloading rules (see 8.6). + +7 Not all contexts where an identifier, character_literal, or operator_symbol are allowed require visibility of a +corresponding declaration. Contexts where visibility is not required are identified by using one of these three syntactic +categories directly in a syntax rule, rather than using direct_name or selector_name. + +24 + +25 + +26/2 + +27 + +28 + +29 + +195 13 December 2012 + +Visibility 8.3 + + Ada Reference Manual — 2012 Edition + +8.3.1 Overriding Indicators + +1/2 + +An overriding_indicator is used to declare that an operation is intended to override (or not override) an +inherited operation. + +2/2 + +3/3 + +4/2 + +5/2 + +6/2 + +7/2 + +8/2 + +9/2 + +10/2 + +11/2 + +12/2 + +13/2 + +14/2 + +15/2 + +16/2 + +overriding_indicator ::= [not] overriding + +Syntax + +Legality Rules + +If an abstract_subprogram_declaration, null_procedure_declaration, expression_function_declaration, +subprogram_body, subprogram_body_stub, subprogram_renaming_declaration, generic_instantiation +of a subprogram, or subprogram_declaration other than a protected subprogram has an overriding_- +indicator, then: + +• +• + +• + +the operation shall be a primitive operation for some type; + +if the overriding_indicator is overriding, then the operation shall override a homograph at the +place of the declaration or body; + +if the overriding_indicator is not overriding, then the operation shall not override any +homograph (at any place). + +In addition to the places where Legality Rules normally apply, these rules also apply in the private part of +an instance of a generic unit. + +NOTES +8 Rules for overriding_indicators of task and protected entries and of protected subprograms are found in 9.5.2 and 9.4, +respectively. + +Examples + +The use of overriding_indicators allows the detection of errors at compile-time that otherwise might not be +detected at all. For instance, we might declare a security queue derived from the Queue interface of 3.9.4 +as: + +type Security_Queue is new Queue with record ...; +overriding +procedure Append(Q : in out Security_Queue; Person : in Person_Name); +overriding +procedure Remove_First(Q : in out Security_Queue; Person : in Person_Name); +overriding +function Cur_Count(Q : in Security_Queue) return Natural; +overriding +function Max_Count(Q : in Security_Queue) return Natural; +not overriding +procedure Arrest(Q : in out Security_Queue; Person : in Person_Name); + +The first four subprogram declarations guarantee that these subprograms will override the four +subprograms inherited from the Queue interface. A misspelling in one of these subprograms will be +detected by the implementation. Conversely, the declaration of Arrest guarantees that this is a new +operation. + +8.3.1 Overriding Indicators + +13 December 2012 196 + + Ada Reference Manual — 2012 Edition + +8.4 Use Clauses + +A use_package_clause achieves direct visibility of declarations that appear in the visible part of a +package; a use_type_clause achieves direct visibility of the primitive operators of a type. + +1 + +use_clause ::= use_package_clause | use_type_clause + +use_package_clause ::= use package_name {, package_name}; + +use_type_clause ::= use [all] type subtype_mark {, subtype_mark}; + +Syntax + +A package_name of a use_package_clause shall denote a nonlimited view of a package. + +Legality Rules + +Static Semantics + +For each use_clause, there is a certain region of text called the scope of the use_clause. For a +use_clause within a context_clause of a library_unit_declaration or library_unit_renaming_declaration, +the scope is the entire declarative region of the declaration. For a use_clause within a context_clause of a +body, the scope is the entire body and any subunits (including multiply nested subunits). The scope does +not include context_clauses themselves. + +For a use_clause immediately within a declarative region, the scope is the portion of the declarative +region starting just after the use_clause and extending to the end of the declarative region. However, the +scope of a use_clause in the private part of a library unit does not include the visible part of any public +descendant of that library unit. + +A package is named in a use_package_clause if it is denoted by a package_name of that clause. A type +is named in a use_type_clause if it is determined by a subtype_mark of that clause. + +For each package named in a use_package_clause whose scope encloses a place, each declaration that +occurs immediately within the declarative region of the package is potentially use-visible at this place if +the declaration is visible at this place. For each type T or T'Class named in a use_type_clause whose +scope encloses a place, the declaration of each primitive operator of type T is potentially use-visible at this +place if its declaration is visible at this place. If a use_type_clause whose scope encloses a place includes +the reserved word all, then the following entities are also potentially use-visible at this place if the +declaration of the entity is visible at this place: + +2 + +3 + +4/3 + +5/2 + +6 + +7 + +7.1/2 + +8/3 + +• Each primitive subprogram of T including each enumeration literal (if any); +• Each subprogram that is declared immediately within the declarative region in which an ancestor + +8.1/3 + +8.2/3 + +type of T is declared and that operates on a class-wide type that covers T. + +Certain implicit declarations may become potentially use-visible in certain contexts as described in 12.6. + +8.3/3 + +A declaration is use-visible if it is potentially use-visible, except in these naming-conflict cases: + +• A potentially use-visible declaration is not use-visible if the place considered is within the + +immediate scope of a homograph of the declaration. + +• Potentially use-visible declarations that have the same identifier are not use-visible unless each + +of them is an overloadable declaration. + +The elaboration of a use_clause has no effect. + +Dynamic Semantics + +9 + +10 + +11 + +12 + +197 13 December 2012 + +Use Clauses 8.4 + + Ada Reference Manual — 2012 Edition + +Example of a use clause in a context clause: +with Ada.Calendar; use Ada; + +Examples + +Example of a use type clause: + +use type Rational_Numbers.Rational; -- see 7.1 +Two_Thirds: Rational_Numbers.Rational := 2/3; + +8.5 Renaming Declarations + +A renaming_declaration declares another name for an entity, such as an object, exception, package, +subprogram, entry, or generic unit. Alternatively, a subprogram_renaming_declaration can be the +completion of a previous subprogram_declaration. + +Syntax + +renaming_declaration ::= + object_renaming_declaration + | exception_renaming_declaration + | package_renaming_declaration + | subprogram_renaming_declaration + | generic_renaming_declaration + +The elaboration of a renaming_declaration evaluates the name that follows the reserved word renames +and thereby determines the view and entity denoted by this name (the renamed view and renamed entity). +A name that denotes the renaming_declaration denotes (a new view of) the renamed entity. + +Dynamic Semantics + +NOTES +9 Renaming may be used to resolve name conflicts and to act as a shorthand. Renaming with a different identifier or +operator_symbol does not hide the old name; the new name and the old name need not be visible at the same places. + +10 A task or protected object that is declared by an explicit object_declaration can be renamed as an object. However, a +single task or protected object cannot be renamed since the corresponding type is anonymous (meaning it has no nameable +subtypes). For similar reasons, an object of an anonymous array or access type cannot be renamed. + +11 A subtype defined without any additional constraint can be used to achieve the effect of renaming another subtype +(including a task or protected subtype) as in + + subtype Mode is Ada.Text_IO.File_Mode; + +13 + +14 + +15 + +16 + +1 + +2 + +3 + +4 + +5 + +6 + +7 + +8.5.1 Object Renaming Declarations + +1 + +An object_renaming_declaration is used to rename an object. + +2/3 + +object_renaming_declaration ::= + defining_identifier : [null_exclusion] subtype_mark renames object_name + [aspect_specification]; + | defining_identifier : access_definition renames object_name + [aspect_specification]; + +Syntax + +3/2 + +The type of the object_name shall resolve to the type determined by the subtype_mark, or in the case +where the type is defined by an access_definition, to an anonymous access type. If the anonymous access + +Name Resolution Rules + +8.4 Use Clauses + +13 December 2012 198 + + Ada Reference Manual — 2012 Edition + +type is an access-to-object type, the type of the object_name shall have the same designated type as that of +the access_definition. If the anonymous access type is an access-to-subprogram type, the type of the +object_name shall have a designated profile that is type conformant with that of the access_definition. + +The renamed entity shall be an object. + +Legality Rules + +In the case where the type is defined by an access_definition, the type of the renamed object and the type +defined by the access_definition: + +• shall both be access-to-object types with statically matching designated subtypes and with both + +or neither being access-to-constant types; or + +• shall both be access-to-subprogram types with subtype conformant designated profiles. + +For an object_renaming_declaration with a null_exclusion or an access_definition that has a +null_exclusion: + +• + +if the object_name denotes a generic formal object of a generic unit G, and the +object_renaming_declaration occurs within the body of G or within the body of a generic unit +declared within the declarative region of G, then the declaration of the formal object of G shall +have a null_exclusion; + +• otherwise, the subtype of the object_name shall exclude null. In addition to the places where +Legality Rules normally apply (see 12.3), this rule applies also in the private part of an instance +of a generic unit. + +The renamed entity shall not be a subcomponent that depends on discriminants of an object whose +nominal subtype is unconstrained unless the object is known to be constrained. A slice of an array shall +not be renamed if this restriction disallows renaming of the array. In addition to the places where Legality +Rules normally apply, these rules apply also in the private part of an instance of a generic unit. + +Static Semantics + +An object_renaming_declaration declares a new view of the renamed object whose properties are +identical to those of the renamed view. Thus, the properties of the renamed object are not affected by the +renaming_declaration. In particular, its value and whether or not it is a constant are unaffected; similarly, +the null exclusion or constraints that apply to an object are not affected by renaming (any constraint +implied by the subtype_mark or access_definition of the object_renaming_declaration is ignored). + +Examples + +Example of renaming an object: + +declare + L : Person renames Leftmost_Person; -- see 3.10.1 +begin + L.Age := L.Age + 1; +end; + +4 + +4.1/2 + +4.2/2 + +4.3/2 + +4.4/2 + +4.5/2 + +4.6/2 + +5/3 + +6/2 + +7 + +8 + +199 13 December 2012 + +Object Renaming Declarations 8.5.1 + + Ada Reference Manual — 2012 Edition + +8.5.2 Exception Renaming Declarations + +1 + +An exception_renaming_declaration is used to rename an exception. + +Syntax +exception_renaming_declaration ::= defining_identifier : exception renames exception_name + [aspect_specification]; + +The renamed entity shall be an exception. + +Legality Rules + +Static Semantics + +An exception_renaming_declaration declares a new view of the renamed exception. + +Example of renaming an exception: + +Examples + +EOF : exception renames Ada.IO_Exceptions.End_Error; -- see A.13 + +2/3 + +3 + +4 + +5 + +6 + +8.5.3 Package Renaming Declarations + +1 + +A package_renaming_declaration is used to rename a package. + +2/3 + +package_renaming_declaration ::= +package defining_program_unit_name renames package_name + [aspect_specification]; + +Syntax + +3 + +The renamed entity shall be a package. + +Legality Rules + +3.1/2 + +If the package_name of a package_renaming_declaration denotes a limited view of a package P, then a +name that denotes the package_renaming_declaration shall occur only within the immediate scope of the +renaming or the scope of a with_clause that mentions the package P or, if P is a nested package, the +innermost library package enclosing P. + +4 + +A package_renaming_declaration declares a new view of the renamed package. + +Static Semantics + +4.1/2 + +At places where the declaration of the limited view of the renamed package is visible, a name that denotes +the package_renaming_declaration denotes a limited view of the package (see 10.1.1). + +5 + +6 + +Example of renaming a package: + +package TM renames Table_Manager; + +Examples + +8.5.2 Exception Renaming Declarations + +13 December 2012 200 + + Ada Reference Manual — 2012 Edition + +8.5.4 Subprogram Renaming Declarations + +A subprogram_renaming_declaration can serve as the completion of a subprogram_declaration; such a +renaming_declaration is called a renaming-as-body. A subprogram_renaming_declaration that is not a +completion is called a renaming-as-declaration, and is used to rename a subprogram (possibly an +enumeration literal) or an entry. + +subprogram_renaming_declaration ::= + [overriding_indicator] + subprogram_specification renames callable_entity_name + [aspect_specification]; + +Syntax + +Name Resolution Rules + +1/3 + +2/3 + +The expected profile for the callable_entity_name is the profile given in the subprogram_specification. + +3 + +The profile of a renaming-as-declaration shall be mode conformant, with that of the renamed callable +entity. + +4/3 + +Legality Rules + +For a parameter or result subtype of the subprogram_specification that has an explicit null_exclusion: + +• + +if the callable_entity_name denotes a generic formal subprogram of a generic unit G, and the +subprogram_renaming_declaration occurs within the body of a generic unit G or within the +body of a generic unit declared within the declarative region of the generic unit G, then the +corresponding parameter or result subtype of the formal subprogram of G shall have a +null_exclusion; + +• otherwise, the subtype of the corresponding parameter or result type of the renamed callable +entity shall exclude null. In addition to the places where Legality Rules normally apply (see +12.3), this rule applies also in the private part of an instance of a generic unit. + +The profile of a renaming-as-body shall conform fully to that of the declaration it completes. If the +renaming-as-body completes that declaration before the subprogram it declares is frozen, the profile shall +be mode conformant with that of the renamed callable entity and the subprogram it declares takes its +convention from the renamed subprogram; otherwise, the profile shall be subtype conformant with that of +the renamed callable entity and the convention of the renamed subprogram shall not be Intrinsic. A +renaming-as-body is illegal if the declaration occurs before the subprogram whose declaration it completes +is frozen, and the renaming renames the subprogram itself, through one or more subprogram renaming +declarations, none of whose subprograms has been frozen. + +The callable_entity_name of a renaming shall not denote a subprogram that requires overriding (see +3.9.3). + +The callable_entity_name of a renaming-as-body shall not denote an abstract subprogram. + +A name that denotes a formal parameter of the subprogram_specification is not allowed within the +callable_entity_name. + +A renaming-as-declaration declares a new view of the renamed entity. The profile of this new view takes +its subtypes, parameter modes, and calling convention from the original profile of the callable entity, while + +Static Semantics + +4.1/2 + +4.2/2 + +4.3/2 + +5/3 + +5.1/2 + +5.2/2 + +6 + +7 + +201 13 December 2012 + +Subprogram Renaming Declarations 8.5.4 + + Ada Reference Manual — 2012 Edition + +the formal parameter names and default_expressions from + +taking +subprogram_renaming_declaration. The new view is a function or procedure, never an entry. + +the profile given + +in + +the + +Dynamic Semantics + +7.1/1 + +8/3 + +For a call to a subprogram whose body is given as a renaming-as-body, the execution of the renaming-as- +body is equivalent to the execution of a subprogram_body that simply calls the renamed subprogram with +its formal parameters as the actual parameters and, if it is a function, returns the value of the call. + +For a call on a renaming of a dispatching subprogram that is overridden, if the overriding occurred before +the renaming, then the body executed is that of the overriding declaration, even if the overriding +declaration is not visible at the place of the renaming; otherwise, the inherited or predefined subprogram is +called. A corresponding rule applies to a call on a renaming of a predefined equality operator for an +untagged record type. + +8.1/1 + +If a subprogram directly or indirectly renames itself, then it is a bounded error to call that subprogram. +Possible consequences are that Program_Error or Storage_Error is raised, or that the call results in infinite +recursion. + +Bounded (Run-Time) Errors + +NOTES +12 A procedure can only be renamed as a procedure. A function whose defining_designator is either an identifier or an +operator_symbol can be renamed with either an identifier or an operator_symbol; for renaming as an operator, the +subprogram specification given in the renaming_declaration is subject to the rules given in 6.6 for operator declarations. +Enumeration literals can be renamed as functions; similarly, attribute_references that denote functions (such as references +to Succ and Pred) can be renamed as functions. An entry can only be renamed as a procedure; the new name is only +allowed to appear in contexts that allow a procedure name. An entry of a family can be renamed, but an entry family +cannot be renamed as a whole. + +13 The operators of the root numeric types cannot be renamed because the types in the profile are anonymous, so the +corresponding specifications cannot be written; the same holds for certain attributes, such as Pos. + +14 Calls with the new name of a renamed entry are procedure_call_statements and are not allowed at places where the +syntax requires an entry_call_statement in conditional_ and timed_entry_calls, nor in an asynchronous_select; similarly, +the Count attribute is not available for the new name. + +15 The primitiveness of a renaming-as-declaration is determined by its profile, and by where it occurs, as for any +declaration of (a view of) a subprogram; primitiveness is not determined by the renamed view. In order to perform a +dispatching call, the subprogram name has to denote a primitive subprogram, not a nonprimitive renaming of a primitive +subprogram. + +Examples of subprogram renaming declarations: + +Examples + +procedure My_Write(C : in Character) renames Pool(K).Write; -- see 4.1.3 +function Real_Plus(Left, Right : Real ) return Real renames "+"; +function Int_Plus (Left, Right : Integer) return Integer renames "+"; +function Rouge return Color renames Red; -- see 3.5.1 +function Rot return Color renames Red; +function Rosso return Color renames Rouge; +function Next(X : Color) return Color renames Color'Succ; -- see 3.5.1 + +Example of a subprogram renaming declaration with new parameter names: + +function "*" (X,Y : Vector) return Real renames Dot_Product; -- see 6.1 + +Example of a subprogram renaming declaration with a new default expression: + +function Minimum(L : Link := Head) return Cell renames Min_Cell; -- see 6.1 + +9 + +10 + +11 + +12 + +13 + +14 + +15 + +16 + +17 + +18 + +19 + +20 + +21 + +8.5.4 Subprogram Renaming Declarations + +13 December 2012 202 + + Ada Reference Manual — 2012 Edition + +8.5.5 Generic Renaming Declarations + +A generic_renaming_declaration is used to rename a generic unit. + +Syntax + +generic_renaming_declaration ::= + generic package + [aspect_specification]; + | generic procedure + [aspect_specification]; + | generic function + [aspect_specification]; + +defining_program_unit_name renames generic_package_name + +defining_program_unit_name renames generic_procedure_name + +defining_program_unit_name renames generic_function_name + +The renamed entity shall be a generic unit of the corresponding kind. + +Legality Rules + +A generic_renaming_declaration declares a new view of the renamed generic unit. + +Static Semantics + +NOTES +16 Although the properties of the new view are the same as those of the renamed view, the place where the +generic_renaming_declaration occurs may affect the legality of subsequent renamings and instantiations that denote the +generic_renaming_declaration, in particular if the renamed generic unit is a library unit (see 10.1.1). + +Example of renaming a generic unit: + +Examples + +generic package Enum_IO renames Ada.Text_IO.Enumeration_IO; -- see A.10.10 + +1 + +2/3 + +3 + +4 + +5 + +6 + +7 + +8.6 The Context of Overload Resolution + +Because declarations can be overloaded, it is possible for an occurrence of a usage name to have more than +one possible interpretation; in most cases, ambiguity is disallowed. This subclause describes how the +possible interpretations resolve to the actual interpretation. + +1/3 + +Certain rules of the language (the Name Resolution Rules) are considered “overloading rules”. If a +possible interpretation violates an overloading rule, it is assumed not to be the intended interpretation; +some other possible interpretation is assumed to be the actual interpretation. On the other hand, violations +of nonoverloading rules do not affect which interpretation is chosen; instead, they cause the construct to be +illegal. To be legal, there usually has to be exactly one acceptable interpretation of a construct that is a +“complete context”, not counting any nested complete contexts. + +The syntax rules of the language and the visibility rules given in 8.3 determine the possible interpretations. +Most type checking rules (rules that require a particular type, or a particular class of types, for example) +are overloading rules. Various rules for the matching of formal and actual parameters are overloading +rules. + +Overload resolution is applied separately to each complete context, not counting inner complete contexts. +Each of the following constructs is a complete context: + +Name Resolution Rules + +• A context_item. + +2 + +3 + +4 + +5 + +203 13 December 2012 + +Generic Renaming Declarations 8.5.5 + + 6 + +7 + +8 + +9 + +10 + +11 + +12 + +13 + +14 + +15 + +16 + +17/3 + +Ada Reference Manual — 2012 Edition + +• A declarative_item or declaration. +• A statement. +• A pragma_argument_association. +• The expression of a case_statement. + +An (overall) interpretation of a complete context embodies its meaning, and includes the following +information about the constituents of the complete context, not including constituents of inner complete +contexts: + +• for each constituent of the complete context, to which syntactic categories it belongs, and by + +which syntax rules; and + +• for each usage name, which declaration it denotes (and, therefore, which view and which entity + +it denotes); and + +• for a complete context that is a declarative_item, whether or not it is a completion of a + +declaration, and (if so) which declaration it completes. + +A possible interpretation is one that obeys the syntax rules and the visibility rules. An acceptable +interpretation is a possible interpretation that obeys the overloading rules, that is, those rules that specify +an expected type or expected profile, or specify how a construct shall resolve or be interpreted. + +The interpretation of a constituent of a complete context is determined from the overall interpretation of +the complete context as a whole. Thus, for example, “interpreted as a function_call,” means that the +construct's interpretation says that it belongs to the syntactic category function_call. + +Each occurrence of a usage name denotes the declaration determined by its interpretation. It also denotes +the view declared by its denoted declaration, except in the following cases: + +• If a usage name appears within the declarative region of a type_declaration and denotes that +same type_declaration, then it denotes the current instance of the type (rather than the type +itself); the current instance of a type is the object or value of the type that is associated with the +execution that evaluates the usage name. Similarly, if a usage name appears within the +declarative region of a subtype_declaration and denotes that same subtype_declaration, then it +denotes the current instance of the subtype. These rules do not apply if the usage name appears +within the subtype_mark of an access_definition for an access-to-object type, or within the +subtype of a parameter or result of an access-to-subprogram type. + +18 + +• If a usage name appears within the declarative region of a generic_declaration (but not within +its generic_formal_part) and it denotes that same generic_declaration, then it denotes the +current instance of the generic unit (rather than the generic unit itself). See also 12.3. + +19 + +A usage name that denotes a view also denotes the entity of that view. + +20/2 + +The expected type for a given expression, name, or other construct determines, according to the type +resolution rules given below, the types considered for the construct during overload resolution. The type +resolution rules provide support for class-wide programming, universal literals, dispatching operations, +and anonymous access types: + +21 + +22 + +23 + +• If a construct is expected to be of any type in a class of types, or of the universal or class-wide +type for a class, then the type of the construct shall resolve to a type in that class or to a +universal type that covers the class. + +• If the expected type for a construct is a specific type T, then the type of the construct shall + +resolve either to T, or: + +• + +to T'Class; or + +8.6 The Context of Overload Resolution + +13 December 2012 204 + + Ada Reference Manual — 2012 Edition + +• + +to a universal type that covers T; or + +• when T is a specific anonymous access-to-object type (see 3.10) with designated type D, to + +an access-to-object type whose designated type is D'Class or is covered by D; or + +24 + +25/2 + +• when T is a named general access-to-object type (see 3.10) with designated type D, to an + +25.1/3 + +anonymous access-to-object type whose designated type covers or is covered by D; or + +• when T is an anonymous access-to-subprogram type (see 3.10), to an access-to-subprogram + +25.2/3 + +type whose designated profile is type conformant with that of T. + +In certain contexts, such as in a subprogram_renaming_declaration, the Name Resolution Rules define an +expected profile for a given name; in such cases, the name shall resolve to the name of a callable entity +whose profile is type conformant with the expected profile. + +26 + +Legality Rules + +When a construct is one that requires that its expected type be a single type in a given class, the type of the +construct shall be determinable solely from the context in which the construct appears, excluding the +construct itself, but using the requirement that it be in the given class. Furthermore, the context shall not +be one that expects any type in some class that contains types of the given class; in particular, the +construct shall not be the operand of a type_conversion. + +Other than for the simple_expression of a membership test, if the expected type for a name or expression +is not the same as the actual type of the name or expression, the actual type shall be convertible to the +expected type (see 4.6); further, if the expected type is a named access-to-object type with designated type +D1 and the actual type is an anonymous access-to-object type with designated type D2, then D1 shall +cover D2, and the name or expression shall denote a view with an accessibility level for which the +statically deeper relationship applies; in particular it shall not denote an access parameter nor a stand-alone +access object. + +A complete context shall have at least one acceptable interpretation; if there is exactly one, then that one is +chosen. + +There is a preference for the primitive operators (and ranges) of the root numeric types root_integer and +root_real. In particular, if two acceptable interpretations of a constituent of a complete context differ only +in that one is for a primitive operator (or range) of the type root_integer or root_real, and the other is not, +the interpretation using the primitive operator (or range) of the root numeric type is preferred. + +27/2 + +27.1/3 + +28 + +29 + +Similarly, there is a preference for the equality operators of the universal_access type (see 4.5.2). If two +acceptable interpretations of a constituent of a complete context differ only in that one is for an equality +operator of the universal_access type, and the other is not, the interpretation using the equality operator of +the universal_access type is preferred. + +29.1/3 + +For a complete context, if there is exactly one overall acceptable interpretation where each constituent's +interpretation is the same as or preferred (in the above sense) over those in all other overall acceptable +interpretations, then that one overall acceptable interpretation is chosen. Otherwise, the complete context +is ambiguous. + +A complete context other than a pragma_argument_association shall not be ambiguous. + +A complete context that is a pragma_argument_association is allowed to be ambiguous (unless otherwise +specified for the particular pragma), but only if every acceptable interpretation of the pragma argument is +as a name that statically denotes a callable entity. Such a name denotes all of the declarations determined +by its interpretations, and all of the views declared by these declarations. + +30 + +31 + +32 + +205 13 December 2012 + +The Context of Overload Resolution 8.6 + + Ada Reference Manual — 2012 Edition + +33 + +34 + +NOTES +17 If a usage name has only one acceptable interpretation, then it denotes the corresponding entity. However, this does +not mean that the usage name is necessarily legal since other requirements exist which are not considered for overload +resolution; for example, the fact that an expression is static, whether an object is constant, mode and subtype conformance +rules, freezing rules, order of elaboration, and so on. + +Similarly, subtypes are not considered for overload resolution (the violation of a constraint does not make a program +illegal but raises an exception during program execution). + +8.6 The Context of Overload Resolution + +13 December 2012 206 + + Ada Reference Manual — 2012 Edition + +9 Tasks and Synchronization + +The execution of an Ada program consists of the execution of one or more tasks. Each task represents a +separate thread of control that proceeds independently and concurrently between the points where it +interacts with other tasks. The various forms of task interaction are described in this clause, and include: + +1/3 + +the activation and termination of a task; + +• +• a call on a protected subprogram of a protected object, providing exclusive read-write access, or + +concurrent read-only access to shared data; + +• a call on an entry, either of another task, allowing for synchronous communication with that +task, or of a protected object, allowing for asynchronous communication with one or more other +tasks using that same protected object; + +• a timed operation, including a simple delay statement, a timed entry call or accept, or a timed + +asynchronous select statement (see next item); + +• an asynchronous transfer of control as part of an asynchronous select statement, where a task +stops what it is doing and begins execution at a different point in response to the completion of +an entry call or the expiration of a delay; + +• an abort statement, allowing one task to cause the termination of another task. + +In addition, tasks can communicate indirectly by reading and updating (unprotected) shared variables, +presuming the access is properly synchronized through some other kind of task interaction. + +The properties of a task are defined by a corresponding task declaration and task_body, which together +define a program unit called a task unit. + +Static Semantics + +Dynamic Semantics + +Over time, tasks proceed through various states. A task is initially inactive; upon activation, and prior to +its termination it is either blocked (as part of some task interaction) or ready to run. While ready, a task +competes for the available execution resources that it requires to run. + +NOTES +1 Concurrent task execution may be implemented on multicomputers, multiprocessors, or with interleaved execution on a +single physical processor. On the other hand, whenever an implementation can determine that the required semantic +effects can be achieved when parts of the execution of a given task are performed by different physical processors acting +in parallel, it may choose to perform them in this way. + +9.1 Task Units and Task Objects + +A task unit is declared by a task declaration, which has a corresponding task_body. A task declaration +may be a task_type_declaration, in which case it declares a named task type; alternatively, it may be a +single_task_declaration, in which case it defines an anonymous task type, as well as declaring a named +task object of that type. + +2 + +3 + +4 + +5 + +6 + +7 + +8 + +9 + +10 + +11 + +1 + +207 13 December 2012 + +Tasks and Synchronization 9 + + Ada Reference Manual — 2012 Edition + +Syntax + +task_type_declaration ::= + task type defining_identifier [known_discriminant_part] + [aspect_specification] [is + [new interface_list with] + task_definition]; + +single_task_declaration ::= + task defining_identifier + [aspect_specification][is + [new interface_list with] + task_definition]; + +task_definition ::= + {task_item} + [ private + {task_item}] + end [task_identifier] + +task_item ::= entry_declaration | aspect_clause + +task_body ::= + task body defining_identifier + [aspect_specification] is + declarative_part + begin + handled_sequence_of_statements + end [task_identifier]; + +If a task_identifier appears at the end of a task_definition or task_body, it shall repeat the +defining_identifier. + +Paragraph 8 was deleted. + +A task_definition defines a task type and its first subtype. The first list of task_items of a task_definition, +together with the known_discriminant_part, if any, is called the visible part of the task unit. The optional +list of task_items after the reserved word private is called the private part of the task unit. + +Static Semantics + +2/3 + +3/3 + +4 + +5/1 + +6/3 + +7 + +9 + +9.1/1 + +For a task declaration without a task_definition, a task_definition without task_items is assumed. + +9.2/3 + +9.3/2 + +9.4/2 + +For a task declaration with an interface_list, the task type inherits user-defined primitive subprograms +from each progenitor type (see 3.9.4), in the same way that a derived type inherits user-defined primitive +subprograms from its progenitor types (see 3.4). If the first parameter of a primitive inherited subprogram +is of the task type or an access parameter designating the task type, and there is an entry_declaration for a +single entry with the same identifier within the task declaration, whose profile is type conformant with the +prefixed view profile of the inherited subprogram, the inherited subprogram is said to be implemented by +the conforming task entry using an implicitly declared nonabstract subprogram which has the same profile +as the inherited subprogram and which overrides it. + +Legality Rules + +A task declaration requires a completion, which shall be a task_body, and every task_body shall be the +completion of some task declaration. + +Each interface_subtype_mark of an interface_list appearing within a task declaration shall denote a +limited interface type that is not a protected interface. + +9.1 Task Units and Task Objects + +13 December 2012 208 + + Ada Reference Manual — 2012 Edition + +The prefixed view profile of an explicitly declared primitive subprogram of a tagged task type shall not be +type conformant with any entry of the task type, if the subprogram has the same defining name as the +entry and the first parameter of the subprogram is of the task type or is an access parameter designating the +task type. + +For each primitive subprogram inherited by the type declared by a task declaration, at most one of the +following shall apply: + +• + +• + +the inherited subprogram is overridden with a primitive subprogram of the task type, in which +case the overriding subprogram shall be subtype conformant with the inherited subprogram and +not abstract; or + +the inherited subprogram is implemented by a single entry of the task type; in which case its +prefixed view profile shall be subtype conformant with that of the task entry. + +If neither applies, the inherited subprogram shall be a null procedure. In addition to the places where +Legality Rules normally apply (see 12.3), these rules also apply in the private part of an instance of a +generic unit. + +Dynamic Semantics + +The elaboration of a task declaration elaborates the task_definition. The elaboration of a single_task_- +declaration also creates an object of an (anonymous) task type. + +The elaboration of a task_definition creates the task type and its first subtype; it also includes the +elaboration of the entry_declarations in the given order. + +9.5/3 + +9.6/2 + +9.7/2 + +9.8/2 + +9.9/2 + +10 + +11 + +As part of the initialization of a task object, any aspect_clauses and any per-object constraints associated +with entry_declarations of the corresponding task_definition are elaborated in the given order. + +12/1 + +The elaboration of a task_body has no effect other than to establish that tasks of the type can from then on +be activated without failing the Elaboration_Check. + +The execution of a task_body is invoked by the activation of a task of the corresponding type (see 9.2). + +The content of a task object of a given task type includes: + +• The values of the discriminants of the task object, if any; +• An entry queue for each entry of the task object; +• A representation of the state of the associated task. + +NOTES +2 Other than in an access_definition, the name of a task unit within the declaration or body of the task unit denotes the +current instance of the unit (see 8.6), rather than the first subtype of the corresponding task type (and thus the name cannot +be used as a subtype_mark). + +3 The notation of a selected_component can be used to denote a discriminant of a task (see 4.1.3). Within a task unit, the +name of a discriminant of the task type denotes the corresponding discriminant of the current instance of the unit. + +4 A task type is a limited type (see 7.5), and hence precludes use of assignment_statements and predefined equality +operators. If an application needs to store and exchange task identities, it can do so by defining an access type designating +the corresponding task objects and by using access values for identification purposes. Assignment is available for such an +access type as for any access type. Alternatively, if the implementation supports the Systems Programming Annex, the +Identity attribute can be used for task identification (see C.7.1). + +13 + +14 + +15 + +16 + +17 + +18 + +19/2 + +20 + +21/2 + +209 13 December 2012 + +Task Units and Task Objects 9.1 + + 22 + +23 + +24/2 + +25 + +26 + +27 + +28 + +29 + +30 + +31 + +32 + +1 + +2/2 + +3/2 + +Ada Reference Manual — 2012 Edition + +Examples of declarations of task types: + +Examples + +task type Server is + entry Next_Work_Item(WI : in Work_Item); + entry Shut_Down; +end Server; +task type Keyboard_Driver(ID : Keyboard_ID := New_ID) is + new Serial_Device with -- see 3.9.4 + entry Read (C : out Character); + entry Write(C : in Character); +end Keyboard_Driver; + +Examples of declarations of single tasks: + +task Controller is + entry Request(Level)(D : Item); -- a family of entries +end Controller; +task Parser is + entry Next_Lexeme(L : in Lexical_Element); + entry Next_Action(A : out Parser_Action); +end; +task User; -- has no entries + +Examples of task objects: + +Agent : Server; +Teletype : Keyboard_Driver(TTY_ID); +Pool : array(1 .. 10) of Keyboard_Driver; + +Example of access type designating task objects: + +type Keyboard is access Keyboard_Driver; +Terminal : Keyboard := new Keyboard_Driver(Term_ID); + +9.2 Task Execution - Task Activation + +Dynamic Semantics + +The execution of a task of a given task type consists of the execution of the corresponding task_body. The +initial part of this execution is called the activation of the task; it consists of the elaboration of the +declarative_part of the task_body. Should an exception be propagated by the elaboration of its +declarative_part, the activation of the task is defined to have failed, and it becomes a completed task. + +A task object (which represents one task) can be a part of a stand-alone object, of an object created by an +allocator, or of an anonymous object of a limited type, or a coextension of one of these. All tasks that are +part or coextensions of any of the stand-alone objects created by the elaboration of object_declarations (or +generic_associations of formal objects of mode in) of a single declarative region are activated together. +All tasks that are part or coextensions of a single object that is not a stand-alone object are activated +together. + +For the tasks of a given declarative region, the activations are initiated within the context of the handled_- +sequence_of_statements (and its associated exception_handlers if any — see 11.2), just prior to +executing the statements of the handled_sequence_of_statements. For a package without an explicit +body or an explicit handled_sequence_of_statements, an implicit body or an implicit null_statement is +assumed, as defined in 7.2. + +9.1 Task Units and Task Objects + +13 December 2012 210 + + Ada Reference Manual — 2012 Edition + +For tasks that are part or coextensions of a single object that is not a stand-alone object, activations are +initiated after completing any initialization of the outermost object enclosing these tasks, prior to +performing any other operation on the outermost object. In particular, for tasks that are part or +coextensions of the object created by the evaluation of an allocator, the activations are initiated as the last +step of evaluating the allocator, prior to returning the new access value. For tasks that are part or +coextensions of an object that is the result of a function call, the activations are not initiated until after the +function returns. + +The task that created the new tasks and initiated their activations (the activator) is blocked until all of +these activations complete (successfully or not). Once all of these activations are complete, if the +activation of any of the tasks has failed (due to the propagation of an exception), Tasking_Error is raised +in the activator, at the place at which it initiated the activations. Otherwise, the activator proceeds with its +execution normally. Any tasks that are aborted prior to completing their activation are ignored when +determining whether to raise Tasking_Error. + +If the master that directly encloses the point where the activation of a task T would be initiated, completes +before the activation of T is initiated, T becomes terminated and is never activated. Furthermore, if a return +statement is left such that the return object is not returned to the caller, any task that was created as a part +of the return object or one of its coextensions immediately becomes terminated and is never activated. + +NOTES +5 An entry of a task can be called before the task has been activated. + +6 If several tasks are activated together, the execution of any of these tasks need not await the end of the activation of the +other tasks. + +7 A task can become completed during its activation either because of an exception or because it is aborted (see 9.8). + +Examples + +Example of task activation: +procedure P is + A, B : Server; -- elaborate the task objects A, B + C : Server; -- elaborate the task object C +begin + -- the tasks A, B, C are activated together before the first statement + ... +end; + +9.3 Task Dependence - Termination of Tasks + +Dynamic Semantics + +4/2 + +5 + +6/3 + +7 + +8 + +9 + +10 + +11 + +Each task (other than an environment task — see 10.2) depends on one or more masters (see 7.6.1), as +follows: + +• If the task is created by the evaluation of an allocator for a given access type, it depends on each +master that includes the elaboration of the declaration of the ultimate ancestor of the given +access type. + +• If the task is created by the elaboration of an object_declaration, it depends on each master that + +includes this elaboration. + +• Otherwise, the task depends on the master of the outermost object of which it is a part (as +determined by the accessibility level of that object — see 3.10.2 and 7.6.1), as well as on any +master whose execution includes that of the master of the outermost object. + +1 + +2 + +3 + +3.1/2 + +211 13 December 2012 + +Task Execution - Task Activation 9.2 + + 4 + +5 + +6/1 + +7/2 + +8 + +9 + +10 + +11 + +12 + +13 + +14 + +15 + +16 + +17 + +18 + +19 + +20 + +Ada Reference Manual — 2012 Edition + +Furthermore, if a task depends on a given master, it is defined to depend on the task that executes the +master, and (recursively) on any master of that task. + +A task is said to be completed when the execution of its corresponding task_body is completed. A task is +said to be terminated when any finalization of the task_body has been performed (see 7.6.1). The first step +of finalizing a master (including a task_body) is to wait for the termination of any tasks dependent on the +master. The task executing the master is blocked until all the dependents have terminated. Any remaining +finalization is then performed and the master is left. + +Completion of a task (and the corresponding task_body) can occur when the task is blocked at a select_- +statement with an open terminate_alternative (see 9.7.1); the open terminate_alternative is selected if +and only if the following conditions are satisfied: + +• The task depends on some completed master; and +• Each task that depends on the master considered is either already terminated or similarly blocked + +at a select_statement with an open terminate_alternative. + +When both conditions are satisfied, the task considered becomes completed, together with all tasks that +depend on the master considered that are not yet completed. + +NOTES +8 The full view of a limited private type can be a task type, or can have subcomponents of a task type. Creation of an +object of such a type creates dependences according to the full type. + +9 An object_renaming_declaration defines a new view of an existing entity and hence creates no further dependence. + +10 The rules given for the collective completion of a group of tasks all blocked on select_statements with open +terminate_alternatives ensure that the collective completion can occur only when there are no remaining active tasks that +could call one of the tasks being collectively completed. + +11 If two or more tasks are blocked on select_statements with open terminate_alternatives, and become completed +collectively, their finalization actions proceed concurrently. + +12 The completion of a task can occur due to any of the following: + +• +• +• +• + +the raising of an exception during the elaboration of the declarative_part of the corresponding task_body; + +the completion of the handled_sequence_of_statements of the corresponding task_body; + +the selection of an open terminate_alternative of a select_statement in the corresponding task_body; + +the abort of the task. + +Example of task dependence: + +Examples + +declare + type Global is access Server; -- see 9.1 + A, B : Server; + G : Global; +begin + -- activation of A and B + declare + type Local is access Server; + X : Global := new Server; -- activation of X.all + L : Local := new Server; -- activation of L.all + C : Server; + begin + -- activation of C + G := X; -- both G and X designate the same task object + ... + end; -- await termination of C and L.all (but not X.all) + ... +end; -- await termination of A, B, and G.all + +9.3 Task Dependence - Termination of Tasks + +13 December 2012 212 + + Ada Reference Manual — 2012 Edition + +9.4 Protected Units and Protected Objects + +A protected object provides coordinated access to shared data, through calls on its visible protected +operations, which can be protected subprograms or protected entries. A protected unit is declared by a +protected declaration, which has a corresponding protected_body. A protected declaration may be a +protected_type_declaration, in which case it declares a named protected type; alternatively, it may be a +single_protected_declaration, in which case it defines an anonymous protected type, as well as declaring +a named protected object of that type. + +Syntax + +protected_type_declaration ::= + protected type defining_identifier [known_discriminant_part] + [aspect_specification] is + [new interface_list with] + protected_definition; + +single_protected_declaration ::= + protected defining_identifier + [aspect_specification] is + [new interface_list with] + protected_definition; + +protected_definition ::= + { protected_operation_declaration } +[ private + { protected_element_declaration } ] + end [protected_identifier] + +protected_operation_declaration ::= subprogram_declaration + | entry_declaration + | aspect_clause + +protected_element_declaration ::= protected_operation_declaration + | component_declaration + +protected_body ::= + protected body defining_identifier + [aspect_specification] is + { protected_operation_item } + end [protected_identifier]; + +protected_operation_item ::= subprogram_declaration + | subprogram_body + | entry_body + | aspect_clause + +If a protected_identifier appears at the end of a protected_definition or protected_body, it shall +repeat the defining_identifier. + +Paragraph 10 was deleted. + +1 + +2/3 + +3/3 + +4 + +5/1 + +6 + +7/3 + +8/1 + +9 + +A protected_definition defines a protected type and its first subtype. The list of protected_operation_- +declarations of a protected_definition, together with the known_discriminant_part, if any, is called the + +11/2 + +Static Semantics + +213 13 December 2012 + +Protected Units and Protected Objects 9.4 + + Ada Reference Manual — 2012 Edition + +visible part of the protected unit. The optional list of protected_element_declarations after the reserved +word private is called the private part of the protected unit. + +11.1/3 + +For a protected declaration with an interface_list, the protected type inherits user-defined primitive +subprograms from each progenitor type (see 3.9.4), in the same way that a derived type inherits user- +defined primitive subprograms from its progenitor types (see 3.4). If the first parameter of a primitive +inherited subprogram is of the protected type or an access parameter designating the protected type, and +there is a protected_operation_declaration for a protected subprogram or single entry with the same +identifier within the protected declaration, whose profile is type conformant with the prefixed view profile +of the inherited subprogram, the inherited subprogram is said to be implemented by the conforming +protected subprogram or entry using an implicitly declared nonabstract subprogram which has the same +profile as the inherited subprogram and which overrides it. + +Legality Rules + +11.2/2 + +A protected declaration requires a completion, which shall be a protected_body, and every protected_- +body shall be the completion of some protected declaration. + +11.3/2 + +Each interface_subtype_mark of an interface_list appearing within a protected declaration shall denote a +limited interface type that is not a task interface. + +11.4/3 + +11.5/2 + +11.6/2 + +11.7/2 + +11.8/2 + +11.9/3 + +The prefixed view profile of an explicitly declared primitive subprogram of a tagged protected type shall +not be type conformant with any protected operation of the protected type, if the subprogram has the same +defining name as the protected operation and the first parameter of the subprogram is of the protected type +or is an access parameter designating the protected type. + +For each primitive subprogram inherited by the type declared by a protected declaration, at most one of +the following shall apply: + +• + +• + +the inherited subprogram is overridden with a primitive subprogram of the protected type, in +which case the overriding subprogram shall be subtype conformant with the inherited +subprogram and not abstract; or + +the inherited subprogram is implemented by a protected subprogram or single entry of the +protected type, in which case its prefixed view profile shall be subtype conformant with that of +the protected subprogram or entry. + +If neither applies, the inherited subprogram shall be a null procedure. In addition to the places where +Legality Rules normally apply (see 12.3), these rules also apply in the private part of an instance of a +generic unit. + +If an inherited subprogram is implemented by a protected procedure or an entry, then the first parameter of +the inherited subprogram shall be of mode out or in out, or an access-to-variable parameter. If an inherited +subprogram is implemented by a protected function, then the first parameter of the inherited subprogram +shall be of mode in, but not an access-to-variable parameter. + +11.10/2 + +If a protected subprogram declaration has an overriding_indicator, then at the point of the declaration: + +11.11/2 + +11.12/2 + +11.13/2 + +• + +• + +if the overriding_indicator is overriding, then the subprogram shall implement an inherited +subprogram; + +if the overriding_indicator is not overriding, then the subprogram shall not implement any +inherited subprogram. + +In addition to the places where Legality Rules normally apply (see 12.3), these rules also apply in the +private part of an instance of a generic unit. + +9.4 Protected Units and Protected Objects + +13 December 2012 214 + + Ada Reference Manual — 2012 Edition + +Dynamic Semantics + +The elaboration of a protected declaration elaborates the protected_definition. The elaboration of a +single_protected_declaration also creates an object of an (anonymous) protected type. + +The elaboration of a protected_definition creates the protected type and its first subtype; it also includes +the elaboration of the component_declarations and protected_operation_declarations in the given order. + +As part of the initialization of a protected object, any per-object constraints (see 3.8) are elaborated. + +The elaboration of a protected_body has no other effect than to establish that protected operations of the +type can from then on be called without failing the Elaboration_Check. + +The content of an object of a given protected type includes: + +• The values of the components of the protected object, including (implicitly) an entry queue for + +each entry declared for the protected object; + +• A representation of the state of the execution resource associated with the protected object (one + +such resource is associated with each protected object). + +The execution resource associated with a protected object has to be acquired to read or update any +components of the protected object; it can be acquired (as part of a protected action — see 9.5.1) either for +concurrent read-only access, or for exclusive read-write access. + +As the first step of the finalization of a protected object, each call remaining on any entry queue of the +object is removed from its queue and Program_Error is raised at the place of the corresponding entry_- +call_statement. + +12 + +13 + +14 + +15 + +16 + +17 + +18 + +19 + +20 + +It is a bounded error to call an entry or subprogram of a protected object after that object is finalized. If the +error is detected, Program_Error is raised. Otherwise, the call proceeds normally, which may leave a task +queued forever. + +20.1/2 + +Bounded (Run-Time) Errors + +NOTES +13 Within the declaration or body of a protected unit other than in an access_definition, the name of the protected unit +denotes the current instance of the unit (see 8.6), rather than the first subtype of the corresponding protected type (and +thus the name cannot be used as a subtype_mark). + +14 A selected_component can be used to denote a discriminant of a protected object (see 4.1.3). Within a protected unit, +the name of a discriminant of the protected type denotes the corresponding discriminant of the current instance of the unit. + +15 A protected type is a limited type (see 7.5), and hence precludes use of assignment_statements and predefined +equality operators. + +16 The bodies of the protected operations given in the protected_body define the actions that take place upon calls to the +protected operations. + +17 The declarations in the private part are only visible within the private part and the body of the protected unit. + +Example of declaration of protected type and corresponding body: + +Examples + +protected type Resource is + entry Seize; + procedure Release; +private + Busy : Boolean := False; +end Resource; + +21/2 + +22 + +23/2 + +24 + +25 + +26 + +27 + +215 13 December 2012 + +Protected Units and Protected Objects 9.4 + + 28 + +29 + +30 + +31 + +32 + +33 + +34 + +35 + +1 + +2/3 + +3/3 + +4/3 + +Ada Reference Manual — 2012 Edition + +protected body Resource is + entry Seize when not Busy is + begin + Busy := True; + end Seize; + procedure Release is + begin + Busy := False; + end Release; +end Resource; + +Example of a single protected declaration and corresponding body: + +protected Shared_Array is + -- Index, Item, and Item_Array are global types + function Component (N : in Index) return Item; + procedure Set_Component(N : in Index; E : in Item); +private + Table : Item_Array(Index) := (others => Null_Item); +end Shared_Array; +protected body Shared_Array is + function Component(N : in Index) return Item is + begin + return Table(N); + end Component; + procedure Set_Component(N : in Index; E : in Item) is + begin + Table(N) := E; + end Set_Component; +end Shared_Array; + +Examples of protected objects: +Control : Resource; +Flags : array(1 .. 100) of Resource; + +9.5 Intertask Communication + +The primary means for intertask communication is provided by calls on entries and protected +subprograms. Calls on protected subprograms allow coordinated access to shared data objects. Entry calls +allow for blocking the caller until a given condition is satisfied (namely, that the corresponding entry is +open — see 9.5.3), and then communicating data or control information directly with another task or +indirectly via a shared protected object. + +Static Semantics + +When a name or prefix denotes an entry, protected subprogram, or a prefixed view of a primitive +subprogram of a limited interface whose first parameter is a controlling parameter, the name or prefix +determines a target object, as follows: + +• If it is a direct_name or expanded name that denotes the declaration (or body) of the operation, +then the target object is implicitly specified to be the current instance of the task or protected +unit immediately enclosing the operation; a call using such a name is defined to be an internal +call; + +• If it is a selected_component that is not an expanded name, then the target object is explicitly +specified to be the object denoted by the prefix of the name; a call using such a name is defined +to be an external call; + +9.4 Protected Units and Protected Objects + +13 December 2012 216 + + Ada Reference Manual — 2012 Edition + +• If the name or prefix is a dereference (implicit or explicit) of an access-to-protected-subprogram +value, then the target object is determined by the prefix of the Access attribute_reference that +produced the access value originally; a call using such a name is defined to be an external call; +• If the name or prefix denotes a subprogram_renaming_declaration, then the target object is as + +determined by the name of the renamed entity. + +A call on an entry or a protected subprogram either uses a name or prefix that determines a target object +implicitly, as above, or is a call on (a non-prefixed view of) a primitive subprogram of a limited interface +whose first parameter is a controlling parameter, in which case the target object is identified explicitly by +the first parameter. This latter case is an external call. + +5/3 + +6 + +6.1/3 + +A corresponding definition of target object applies to a requeue_statement (see 9.5.4), with a +corresponding distinction between an internal requeue and an external requeue. + +7 + +If a name or prefix determines a target object, and the name denotes a protected entry or procedure, then +the target object shall be a variable, unless the prefix is for an attribute_reference to the Count attribute +(see 9.9). + +7.1/3 + +Legality Rules + +Dynamic Semantics + +Within the body of a protected operation, the current instance (see 8.6) of the immediately enclosing +protected unit is determined by the target object specified (implicitly or explicitly) in the call (or requeue) +on the protected operation. + +Any call on a protected procedure or entry of a target protected object is defined to be an update to the +object, as is a requeue on such an entry. + +synchronization_kind ::= By_Entry | By_Protected_Procedure | Optional + +Syntax + +Static Semantics + +For the declaration of a primitive procedure of a synchronized tagged type the following language-defined +representation aspect may be specified with an aspect_specification (see 13.1.1): + +Synchronization + +If specified, the aspect definition shall be a synchronization_kind. + +Inherited subprograms inherit the Synchronization aspect, if any, from the corresponding subprogram of +the parent or progenitor type. If an overriding operation does not have a directly specified Synchronization +aspect then the Synchronization aspect of the inherited operation is inherited by the overriding operation. + +Legality Rules + +The synchronization_kind By_Protected_Procedure shall not be applied to a primitive procedure of a task +interface. + +A procedure for which the specified synchronization_kind is By_Entry shall be implemented by an entry. +A procedure for which the specified synchronization_kind is By_Protected_Procedure shall be +implemented by a protected procedure. A procedure for which the specified synchronization_kind is +Optional may be implemented by an entry or by a procedure (including a protected procedure). + +If a primitive procedure overrides an inherited operation for which the Synchronization aspect has been +specified to be By_Entry or By_Protected_Procedure, then any specification of the aspect Synchronization +applied to the overriding operation shall have the same synchronization_kind. + +8 + +9 + +10/3 + +11/3 + +12/3 + +13/3 + +14/3 + +15/3 + +16/3 + +217 13 December 2012 + +Intertask Communication 9.5 + + + Ada Reference Manual — 2012 Edition + +17/3 + +In addition to the places where Legality Rules normally apply (see 12.3), these rules also apply in the +private part of an instance of a generic unit. + +18/3 + +NOTES +18 The synchronization_kind By_Protected_Procedure implies that the operation will not block. + +9.5.1 Protected Subprograms and Protected Actions + +A protected subprogram is a subprogram declared immediately within a protected_definition. Protected +procedures provide exclusive read-write access to the data of a protected object; protected functions +provide concurrent read-only access to the data. + +Static Semantics + +Within the body of a protected function (or a function declared immediately within a protected_body), the +current instance of the enclosing protected unit is defined to be a constant (that is, its subcomponents may +be read but not updated). Within the body of a protected procedure (or a procedure declared immediately +within a protected_body), and within an entry_body, the current instance is defined to be a variable +(updating is permitted). + +Dynamic Semantics + +For the execution of a call on a protected subprogram, the evaluation of the name or prefix and of the +parameter associations, and any assigning back of in out or out parameters, proceeds as for a normal +subprogram call (see 6.4). If the call is an internal call (see 9.5), the body of the subprogram is executed as +for a normal subprogram call. If the call is an external call, then the body of the subprogram is executed as +part of a new protected action on the target protected object; the protected action completes after the body +of the subprogram is executed. A protected action can also be started by an entry call (see 9.5.3). + +A new protected action is not started on a protected object while another protected action on the same +protected object is underway, unless both actions are the result of a call on a protected function. This rule +is expressible in terms of the execution resource associated with the protected object: + +• Starting a protected action on a protected object corresponds to acquiring the execution resource +associated with the protected object, either for concurrent read-only access if the protected +action is for a call on a protected function, or for exclusive read-write access otherwise; +• Completing the protected action corresponds to releasing the associated execution resource. + +After performing an operation on a protected object other than a call on a protected function, but prior to +completing the associated protected action, the entry queues (if any) of the protected object are serviced +(see 9.5.3). + +During a protected action, it is a bounded error to invoke an operation that is potentially blocking. The +following are defined to be potentially blocking operations: + +Bounded (Run-Time) Errors + +• a select_statement; +• an accept_statement; +• an entry_call_statement; +• a delay_statement; +• an abort_statement; +• + +task creation or activation; + +1 + +2 + +3 + +4 + +5 + +6 + +7 + +8 + +9 + +10 + +11 + +12 + +13 + +14 + +9.5 Intertask Communication + +13 December 2012 218 + + Ada Reference Manual — 2012 Edition + +• an external call on a protected subprogram (or an external requeue) with the same target object + +as that of the protected action; + +• a call on a subprogram whose body contains a potentially blocking operation. + +If the bounded error is detected, Program_Error is raised. If not detected, the bounded error might result in +deadlock or a (nested) protected action on the same target object. + +Certain language-defined subprograms are potentially blocking. In particular, the subprograms of the +language-defined input-output packages that manipulate files (implicitly or explicitly) are potentially +blocking. Other potentially blocking subprograms are identified where they are defined. When not +specified as potentially blocking, a language-defined subprogram is nonblocking. + +NOTES +19 If two tasks both try to start a protected action on a protected object, and at most one is calling a protected function, +then only one of the tasks can proceed. Although the other task cannot proceed, it is not considered blocked, and it might +be consuming processing resources while it awaits its turn. There is no language-defined ordering or queuing presumed +for tasks competing to start a protected action — on a multiprocessor such tasks might use busy-waiting; for +monoprocessor considerations, see D.3, “Priority Ceiling Locking”. + +20 The body of a protected unit may contain declarations and bodies for local subprograms. These are not visible outside +the protected unit. + +21 The body of a protected function can contain internal calls on other protected functions, but not protected procedures, +because the current instance is a constant. On the other hand, the body of a protected procedure can contain internal calls +on both protected functions and procedures. + +22 From within a protected action, an internal call on a protected subprogram, or an external call on a protected +subprogram with a different target object is not considered a potentially blocking operation. + +15 + +16 + +17 + +18 + +19 + +20 + +21 + +22 + +23 The pragma Detect_Blocking may be used to ensure that all executions of potentially blocking operations during a +protected action raise Program_Error. See H.5. + +22.1/2 + +Examples of protected subprogram calls (see 9.4): + +Shared_Array.Set_Component(N, E); +E := Shared_Array.Component(M); +Control.Release; + +Examples + +9.5.2 Entries and Accept Statements + +23 + +24 + +Entry_declarations, with the corresponding entry_bodies or accept_statements, are used to define +potentially queued operations on tasks and protected objects. + +1 + +entry_declaration ::= + [overriding_indicator] + entry defining_identifier [(discrete_subtype_definition)] parameter_profile + [aspect_specification]; + +Syntax + +accept_statement ::= + accept entry_direct_name [(entry_index)] parameter_profile [do + handled_sequence_of_statements + end [entry_identifier]]; + +entry_index ::= expression + +2/3 + +3 + +4 + +219 13 December 2012 + +Protected Subprograms and Protected Actions 9.5.1 + + 5 + +6 + +7 + +8 + +9 + +10 + +10.1/2 + +11 + +12 + +Ada Reference Manual — 2012 Edition + +entry_body ::= + entry defining_identifier entry_body_formal_part entry_barrier is + declarative_part + begin + handled_sequence_of_statements + end [entry_identifier]; + +entry_body_formal_part ::= [(entry_index_specification)] parameter_profile + +entry_barrier ::= when condition + +entry_index_specification ::= for defining_identifier in discrete_subtype_definition + +If an entry_identifier appears at the end of an accept_statement, it shall repeat the entry_direct_- +name. If an entry_identifier appears at the end of an entry_body, it shall repeat the defining_- +identifier. + +An entry_declaration is allowed only in a protected or task declaration. + +An overriding_indicator is not allowed in an entry_declaration that includes a +discrete_subtype_definition. + +Name Resolution Rules + +In an accept_statement, the expected profile for the entry_direct_name is that of the entry_declaration; +the expected type for an entry_index is that of the subtype defined by the discrete_subtype_definition of +the corresponding entry_declaration. + +Within the handled_sequence_of_statements of an accept_statement, if a selected_component has a +prefix that denotes the corresponding entry_declaration, then the entity denoted by the prefix is the +accept_statement, and the selected_component is interpreted as an expanded name (see 4.1.3); the +selector_name of the selected_component has to be the identifier for some formal parameter of the +accept_statement. + +Legality Rules + +13 + +An entry_declaration in a task declaration shall not contain a specification for an access parameter (see +3.10). + +13.1/2 + +If an entry_declaration has an overriding_indicator, then at the point of the declaration: + +13.2/2 + +13.3/2 + +13.4/2 + +14 + +• + +• + +if the overriding_indicator is overriding, then the entry shall implement an inherited +subprogram; + +if the overriding_indicator is not overriding, then the entry shall not implement any inherited +subprogram. + +In addition to the places where Legality Rules normally apply (see 12.3), these rules also apply in the +private part of an instance of a generic unit. + +For an accept_statement, the innermost enclosing body shall be a task_body, and the entry_direct_name +shall denote an entry_declaration in the corresponding task declaration; the profile of the accept_- +statement shall conform fully to that of the corresponding entry_declaration. An accept_statement shall +have a parenthesized entry_index if and only if the corresponding entry_declaration has a discrete_- +subtype_definition. + +15 + +An accept_statement shall not be within another accept_statement that corresponds to the same entry_- +declaration, nor within an asynchronous_select inner to the enclosing task_body. + +9.5.2 Entries and Accept Statements + +13 December 2012 220 + + Ada Reference Manual — 2012 Edition + +An entry_declaration of a protected unit requires a completion, which shall be an entry_body, and every +entry_body shall be the completion of an entry_declaration of a protected unit. The profile of the entry_- +body shall conform fully to that of the corresponding declaration. + +An entry_body_formal_part shall have an entry_index_specification if and only if the corresponding +entry_declaration has a discrete_subtype_definition. In this case, the discrete_subtype_definitions of the +entry_declaration and the entry_index_specification shall fully conform to one another (see 6.3.1). + +A name that denotes a formal parameter of an entry_body is not allowed within the entry_barrier of the +entry_body. + +Static Semantics + +The parameter modes defined for parameters in the parameter_profile of an entry_declaration are the +same as for a subprogram_declaration and have the same meaning (see 6.2). + +An entry_declaration with a discrete_subtype_definition (see 3.6) declares a family of distinct entries +having the same profile, with one such entry for each value of the entry index subtype defined by the +discrete_subtype_definition. A name for an entry of a family takes the form of an indexed_component, +where the prefix denotes the entry_declaration for the family, and the index value identifies the entry +within the family. The term single entry is used to refer to any entry other than an entry of an entry family. + +In the entry_body for an entry family, the entry_index_specification declares a named constant whose +subtype is the entry index subtype defined by the corresponding entry_declaration; the value of the named +entry index identifies which entry of the family was called. + +16 + +17 + +18 + +19 + +20 + +21 + +Dynamic Semantics + +The elaboration of an entry_declaration for an entry family consists of the elaboration of the discrete_- +subtype_definition, as described in 3.8. The elaboration of an entry_declaration for a single entry has no +effect. + +22/1 + +The actions to be performed when an entry is called are specified by the corresponding accept_- +statements (if any) for an entry of a task unit, and by the corresponding entry_body for an entry of a +protected unit. + +For the execution of an accept_statement, the entry_index, if any, is first evaluated and converted to the +entry index subtype; this index value identifies which entry of the family is to be accepted. Further +execution of the accept_statement is then blocked until a caller of the corresponding entry is selected (see +9.5.3), whereupon the handled_sequence_of_statements, if any, of the accept_statement is executed, +with the formal parameters associated with the corresponding actual parameters of the selected entry call. +Upon completion of the handled_sequence_of_statements, the accept_statement completes and is left. +When an exception is propagated from the handled_sequence_of_statements of an accept_statement, +the same exception is also raised by the execution of the corresponding entry_call_statement. + +The above interaction between a calling task and an accepting task is called a rendezvous. After a +rendezvous, the two tasks continue their execution independently. + +An entry_body is executed when the condition of the entry_barrier evaluates to True and a caller of the +corresponding single entry, or entry of the corresponding entry family, has been selected (see 9.5.3). For +the execution of the entry_body, the declarative_part of the entry_body is elaborated, and the handled_- +sequence_of_statements of the body is executed, as for the execution of a subprogram_body. The value +of the named entry index, if any, is determined by the value of the entry index specified in the entry_name +of the selected entry call (or intermediate requeue_statement — see 9.5.4). + +23 + +24 + +25 + +26 + +221 13 December 2012 + +Entries and Accept Statements 9.5.2 + + 27 + +28 + +29/2 + +30 + +31 + +32 + +33 + +34 + +35 + +36 + +37 + +1 + +2 + +3 + +4 + +5 + +Ada Reference Manual — 2012 Edition + +NOTES +24 A task entry has corresponding accept_statements (zero or more), whereas a protected entry has a corresponding +entry_body (exactly one). + +25 A consequence of the rule regarding the allowed placements of accept_statements is that a task can execute +accept_statements only for its own entries. + +26 A return statement (see 6.5) or a requeue_statement (see 9.5.4) may be used to complete the execution of an +accept_statement or an entry_body. + +27 The condition in the entry_barrier may reference anything visible except the formal parameters of the entry. This +includes the entry index (if any), the components (including discriminants) of the protected object, the Count attribute of +an entry of that protected object, and data global to the protected unit. + +The restriction against referencing the formal parameters within an entry_barrier ensures that all calls of the same entry +see the same barrier value. If it is necessary to look at the parameters of an entry call before deciding whether to handle it, +the entry_barrier can be “when True” and the caller can be requeued (on some private entry) when its parameters indicate +that it cannot be handled immediately. + +Examples of entry declarations: + +entry Read(V : out Item); +entry Seize; +entry Request(Level)(D : Item); -- a family of entries + +Examples + +Examples of accept statements: +accept Shut_Down; +accept Read(V : out Item) do + V := Local_Item; +end Read; +accept Request(Low)(D : Item) do + ... +end Request; + +9.5.3 Entry Calls + +An entry_call_statement (an entry call) can appear in various contexts. A simple entry call is a stand- +alone statement that represents an unconditional call on an entry of a target task or a protected object. +Entry calls can also appear as part of select_statements (see 9.7). + +entry_call_statement ::= entry_name [actual_parameter_part]; + +Syntax + +Name Resolution Rules + +The entry_name given in an entry_call_statement shall resolve to denote an entry. The rules for +parameter associations are the same as for subprogram calls (see 6.4 and 6.4.1). + +The entry_name of an entry_call_statement specifies (explicitly or implicitly) the target object of the call, +the entry or entry family, and the entry index, if any (see 9.5). + +Static Semantics + +Under certain circumstances (detailed below), an entry of a task or protected object is checked to see +whether it is open or closed: + +Dynamic Semantics + +9.5.2 Entries and Accept Statements + +13 December 2012 222 + + Ada Reference Manual — 2012 Edition + +• An entry of a task is open if the task is blocked on an accept_statement that corresponds to the +entry (see 9.5.2), or on a selective_accept (see 9.7.1) with an open accept_alternative that +corresponds to the entry; otherwise, it is closed. + +• An entry of a protected object is open if the condition of the entry_barrier of the corresponding +entry_body evaluates to True; otherwise, it is closed. If the evaluation of the condition +propagates an exception, the exception Program_Error is propagated to all current callers of all +entries of the protected object. + +For the execution of an entry_call_statement, evaluation of the name and of the parameter associations is +as for a subprogram call (see 6.4). The entry call is then issued: For a call on an entry of a protected object, +a new protected action is started on the object (see 9.5.1). The named entry is checked to see if it is open; +if open, the entry call is said to be selected immediately, and the execution of the call proceeds as follows: +• For a call on an open entry of a task, the accepting task becomes ready and continues the + +execution of the corresponding accept_statement (see 9.5.2). + +• For a call on an open entry of a protected object, the corresponding entry_body is executed (see + +9.5.2) as part of the protected action. + +If the accept_statement or entry_body completes other than by a requeue (see 9.5.4), return is made to +the caller (after servicing the entry queues — see below); any necessary assigning back of formal to actual +parameters occurs, as for a subprogram call (see 6.4.1); such assignments take place outside of any +protected action. + +If the named entry is closed, the entry call is added to an entry queue (as part of the protected action, for a +call on a protected entry), and the call remains queued until it is selected or cancelled; there is a separate +(logical) entry queue for each entry of a given task or protected object (including each entry of an entry +family). + +When a queued call is selected, it is removed from its entry queue. Selecting a queued call from a +particular entry queue is called servicing the entry queue. An entry with queued calls can be serviced +under the following circumstances: + +• When the associated task reaches a corresponding accept_statement, or a selective_accept + +with a corresponding open accept_alternative; + +• If after performing, as part of a protected action on the associated protected object, an operation +on the object other than a call on a protected function, the entry is checked and found to be open. + +If there is at least one call on a queue corresponding to an open entry, then one such call is selected +according to the entry queuing policy in effect (see below), and the corresponding accept_statement or +entry_body is executed as above for an entry call that is selected immediately. + +The entry queuing policy controls selection among queued calls both for task and protected entry queues. +The default entry queuing policy is to select calls on a given entry queue in order of arrival. If calls from +two or more queues are simultaneously eligible for selection, the default entry queuing policy does not +specify which queue is serviced first. Other entry queuing policies can be specified by pragmas (see D.4). + +For a protected object, the above servicing of entry queues continues until there are no open entries with +queued calls, at which point the protected action completes. + +For an entry call that is added to a queue, and that is not the triggering_statement of an asynchronous_- +select (see 9.7.4), the calling task is blocked until the call is cancelled, or the call is selected and a +corresponding accept_statement or entry_body completes without requeuing. In addition, the calling task +is blocked during a rendezvous. + +6/3 + +7/3 + +8 + +9 + +10 + +11 + +12 + +13 + +14 + +15 + +16 + +17 + +18 + +19 + +223 13 December 2012 + +Entry Calls 9.5.3 + + 20 + +21 + +22 + +23 + +24 + +25 + +26 + +27 + +28 + +29 + +30 + +31 + +Ada Reference Manual — 2012 Edition + +An attempt can be made to cancel an entry call upon an abort (see 9.8) and as part of certain forms of +select_statement (see 9.7.2, 9.7.3, and 9.7.4). The cancellation does not take place until a point (if any) +when the call is on some entry queue, and not protected from cancellation as part of a requeue (see 9.5.4); +at such a point, the call is removed from the entry queue and the call completes due to the cancellation. +The cancellation of a call on an entry of a protected object is a protected action, and as such cannot take +place while any other protected action is occurring on the protected object. Like any protected action, it +includes servicing of the entry queues (in case some entry barrier depends on a Count attribute). + +A call on an entry of a task that has already completed its execution raises the exception Tasking_Error at +the point of the call; similarly, this exception is raised at the point of the call if the called task completes +its execution or becomes abnormal before accepting the call or completing the rendezvous (see 9.8). This +applies equally to a simple entry call and to an entry call as part of a select_statement. + +Implementation Permissions + +An implementation may perform the sequence of steps of a protected action using any thread of control; it +need not be that of the task that started the protected action. If an entry_body completes without +requeuing, then the corresponding calling task may be made ready without waiting for the entire protected +action to complete. + +When the entry of a protected object is checked to see whether it is open, the implementation need not +reevaluate the condition of the corresponding entry_barrier if no variable or attribute referenced by the +condition (directly or indirectly) has been altered by the execution (or cancellation) of a protected +procedure or entry call on the object since the condition was last evaluated. + +An implementation may evaluate the conditions of all entry_barriers of a given protected object any time +any entry of the object is checked to see if it is open. + +When an attempt is made to cancel an entry call, the implementation need not make the attempt using the +thread of control of the task (or interrupt) that initiated the cancellation; in particular, it may use the thread +of control of the caller itself to attempt the cancellation, even if this might allow the entry call to be +selected in the interim. + +NOTES +28 If an exception is raised during the execution of an entry_body, it is propagated to the corresponding caller (see 11.4). + +29 For a call on a protected entry, the entry is checked to see if it is open prior to queuing the call, and again thereafter if +its Count attribute (see 9.9) is referenced in some entry barrier. + +30 In addition to simple entry calls, the language permits timed, conditional, and asynchronous entry calls (see 9.7.2, +9.7.3, and see 9.7.4). + +31 The condition of an entry_barrier is allowed to be evaluated by an implementation more often than strictly necessary, +even if the evaluation might have side effects. On the other hand, an implementation need not reevaluate the condition if +nothing it references was updated by an intervening protected action on the protected object, even if the condition +references some global variable that might have been updated by an action performed from outside of a protected action. + +Examples + +Examples of entry calls: + +Agent.Shut_Down; -- see 9.1 +Parser.Next_Lexeme(E); -- see 9.1 +Pool(5).Read(Next_Char); -- see 9.1 +Controller.Request(Low)(Some_Item); -- see 9.1 +Flags(3).Seize; -- see 9.4 + +9.5.3 Entry Calls + +13 December 2012 224 + + Ada Reference Manual — 2012 Edition + +9.5.4 Requeue Statements + +A requeue_statement can be used to complete an accept_statement or entry_body, while redirecting the +corresponding entry call to a new (or the same) entry queue. Such a requeue can be performed with or +without allowing an intermediate cancellation of the call, due to an abort or the expiration of a delay. + +requeue_statement ::= requeue procedure_or_entry_name [with abort]; + +Syntax + +Name Resolution Rules + +The procedure_or_entry_name of a requeue_statement shall resolve to denote a procedure or an entry +(the requeue target). The profile of the entry, or the profile or prefixed profile of the procedure, shall +either have no parameters, or be type conformant (see 6.3.1) with the profile of the innermost enclosing +entry_body or accept_statement. + +Legality Rules + +A requeue_statement shall be within a callable construct that is either an entry_body or an +accept_statement, and this construct shall be the innermost enclosing body or callable construct. + +If the requeue target has parameters, then its (prefixed) profile shall be subtype conformant with the profile +of the innermost enclosing callable construct. + +If the target is a procedure, the name shall denote a renaming of an entry, or shall denote a view or a +prefixed view of a primitive subprogram of a synchronized interface, where the first parameter of the +unprefixed view of the primitive subprogram shall be a controlling parameter, and the Synchronization +aspect shall be specified with synchronization_kind By_Entry for the primitive subprogram. + +In a requeue_statement of an accept_statement of some task unit, either the target object shall be a part +of a formal parameter of the accept_statement, or the accessibility level of the target object shall not be +equal to or statically deeper than any enclosing accept_statement of the task unit. In a requeue_- +statement of an entry_body of some protected unit, either the target object shall be a part of a formal +parameter of the entry_body, or the accessibility level of the target object shall not be statically deeper +than that of the entry_declaration for the entry_body. + +Dynamic Semantics + +The execution of a requeue_statement proceeds by first evaluating the procedure_or_entry_name, +including the prefix identifying the target task or protected object and the expression identifying the entry +within an entry family, if any. The entry_body or accept_statement enclosing the requeue_statement is +then completed, finalized, and left (see 7.6.1). + +For the execution of a requeue on an entry of a target task, after leaving the enclosing callable construct, +the named entry is checked to see if it is open and the requeued call is either selected immediately or +queued, as for a normal entry call (see 9.5.3). + +For the execution of a requeue on an entry of a target protected object, after leaving the enclosing callable +construct: + +• + +if the requeue is an internal requeue (that is, the requeue is back on an entry of the same +protected object — see 9.5), the call is added to the queue of the named entry and the ongoing +protected action continues (see 9.5.1); + +1 + +2/3 + +3/3 + +4 + +5/3 + +5.1/3 + +6/3 + +7/3 + +8 + +9 + +10 + +225 13 December 2012 + +Requeue Statements 9.5.4 + + Ada Reference Manual — 2012 Edition + +11 + +• + +if the requeue is an external requeue (that is, the target protected object is not implicitly the same +as the current object — see 9.5), a protected action is started on the target object and proceeds as +for a normal entry call (see 9.5.3). + +12/3 + +If the requeue target named in the requeue_statement has formal parameters, then during the execution of +the accept_statement or entry_body corresponding to the new entry, the formal parameters denote the +same objects as did the corresponding formal parameters of the callable construct completed by the +requeue. In any case, no parameters are specified in a requeue_statement; any parameter passing is +implicit. + +13 + +14 + +15 + +16 + +17 + +18 + +19 + +20 + +1 + +2 + +3 + +4 + +5 + +If the requeue_statement includes the reserved words with abort (it is a requeue-with-abort), then: + +• + +• + +if the original entry call has been aborted (see 9.8), then the requeue acts as an abort completion +point for the call, and the call is cancelled and no requeue is performed; + +if the original entry call was timed (or conditional), then the original expiration time is the +expiration time for the requeued call. + +If the reserved words with abort do not appear, then the call remains protected against cancellation while +queued as the result of the requeue_statement. + +NOTES +32 A requeue is permitted from a single entry to an entry of an entry family, or vice-versa. The entry index, if any, plays +no part in the subtype conformance check between the profiles of the two entries; an entry index is part of the entry_name +for an entry of a family. + +Examples of requeue statements: + +Examples + +requeue Request(Medium) with abort; + -- requeue on a member of an entry family of the current task, see 9.1 +requeue Flags(I).Seize; + -- requeue on an entry of an array component, see 9.4 + +9.6 Delay Statements, Duration, and Time + +A delay_statement is used to block further execution until a specified expiration time is reached. The +expiration time can be specified either as a particular point in time (in a delay_until_statement), or in +seconds from the current time (in a delay_relative_statement). The language-defined package Calendar +provides definitions for a type Time and associated operations, including a function Clock that returns the +current time. + +delay_statement ::= delay_until_statement | delay_relative_statement + +delay_until_statement ::= delay until delay_expression; + +delay_relative_statement ::= delay delay_expression; + +Syntax + +Name Resolution Rules + +The expected type for the delay_expression in a delay_relative_statement is the predefined type +Duration. The delay_expression in a delay_until_statement is expected to be of any nonlimited type. + +6/3 + +There can be multiple time bases, each with a corresponding clock, and a corresponding time type. The +type of the delay_expression in a delay_until_statement shall be a time type — either the type Time + +Legality Rules + +9.5.4 Requeue Statements + +13 December 2012 226 + + Ada Reference Manual — 2012 Edition + +defined in the language-defined package Calendar (see below), the type Time in the package Real_Time +(see D.8), or some other implementation-defined time type. + +Static Semantics + +There is a predefined fixed point type named Duration, declared in the visible part of package Standard; a +value of type Duration is used to represent the length of an interval of time, expressed in seconds. The type +Duration is not specific to a particular time base, but can be used with any time base. + +A value of the type Time in package Calendar, or of some other time type, represents a time as reported by +a corresponding clock. + +The following language-defined library package exists: + +package Ada.Calendar is + type Time is private; + subtype Year_Number is Integer range 1901 .. 2399; + subtype Month_Number is Integer range 1 .. 12; + subtype Day_Number is Integer range 1 .. 31; + subtype Day_Duration is Duration range 0.0 .. 86_400.0; + function Clock return Time; + function Year (Date : Time) return Year_Number; + function Month (Date : Time) return Month_Number; + function Day (Date : Time) return Day_Number; + function Seconds(Date : Time) return Day_Duration; + procedure Split (Date : in Time; + Year : out Year_Number; + Month : out Month_Number; + Day : out Day_Number; + Seconds : out Day_Duration); + function Time_Of(Year : Year_Number; + Month : Month_Number; + Day : Day_Number; + Seconds : Day_Duration := 0.0) + return Time; + function "+" (Left : Time; Right : Duration) return Time; + function "+" (Left : Duration; Right : Time) return Time; + function "-" (Left : Time; Right : Duration) return Time; + function "-" (Left : Time; Right : Time) return Duration; + function "<" (Left, Right : Time) return Boolean; + function "<="(Left, Right : Time) return Boolean; + function ">" (Left, Right : Time) return Boolean; + function ">="(Left, Right : Time) return Boolean; + Time_Error : exception; +private + ... -- not specified by the language +end Ada.Calendar; + +Dynamic Semantics + +the execution of a delay_statement, + +For +first evaluated. For a +delay_until_statement, the expiration time for the delay is the value of the delay_expression, in the time +base associated with the type of the expression. For a delay_relative_statement, the expiration time is +defined as the current time, in the time base associated with relative delays, plus the value of the +delay_expression converted to the type Duration, and then rounded up to the next clock tick. The time +base associated with relative delays is as defined in D.9, “Delay Accuracy” or is implementation defined. + +the delay_expression + +is + +7 + +8/3 + +9 + +10 + +11/2 + +12 + +13 + +14 + +15 + +16 + +17 + +18 + +19 + +20 + +227 13 December 2012 + +Delay Statements, Duration, and Time 9.6 + + + Ada Reference Manual — 2012 Edition + +21 + +22/3 + +23 + +24/2 + +25 + +26/1 + +27 + +The task executing a delay_statement is blocked until the expiration time is reached, at which point it +becomes ready again. If the expiration time has already passed, the task is not blocked. + +If an attempt is made to cancel the delay_statement (as part of an asynchronous_select or abort — see +9.7.4 and 9.8), the statement is cancelled if the expiration time has not yet passed, thereby completing the +delay_statement. + +The time base associated with the type Time of package Calendar is implementation defined. The function +Clock of package Calendar returns a value representing the current time for this time base. The +implementation-defined value of the named number System.Tick (see 13.7) is an approximation of the +length of the real-time interval during which the value of Calendar.Clock remains constant. + +The functions Year, Month, Day, and Seconds return the corresponding values for a given value of the +type Time, as appropriate to an implementation-defined time zone; the procedure Split returns all four +corresponding values. Conversely, the function Time_Of combines a year number, a month number, a day +number, and a duration, into a value of type Time. The operators "+" and "–" for addition and subtraction +of times and durations, and the relational operators for times, have the conventional meaning. + +If Time_Of is called with a seconds value of 86_400.0, the value returned is equal to the value of Time_Of +for the next day with a seconds value of 0.0. The value returned by the function Seconds or through the +Seconds parameter of the procedure Split is always less than 86_400.0. + +The exception Time_Error is raised by the function Time_Of if the actual parameters do not form a proper +date. This exception is also raised by the operators "+" and "–" if the result is not representable in the type +Time or Duration, as appropriate. This exception is also raised by the functions Year, Month, Day, and +Seconds and the procedure Split if the year number of the given date is outside of the range of the subtype +Year_Number. + +Implementation Requirements + +The implementation of the type Duration shall allow representation of time intervals (both positive and +negative) up to at least 86400 seconds (one day); Duration'Small shall not be greater than twenty +milliseconds. The implementation of the type Time shall allow representation of all dates with year +numbers in the range of Year_Number; it may allow representation of other dates as well (both earlier and +later). + +28/3 + +An implementation may define additional time types. + +Implementation Permissions + +29 + +30 + +31 + +32 + +An implementation may raise Time_Error if the value of a delay_expression in a delay_until_statement +of a select_statement represents a time more than 90 days past the current time. The actual limit, if any, is +implementation-defined. + +Implementation Advice + +Whenever possible in an implementation, the value of Duration'Small should be no greater than 100 +microseconds. + +The time base for delay_relative_statements should be monotonic; it need not be the same time base as +used for Calendar.Clock. + +NOTES +33 A delay_relative_statement with a negative value of the delay_expression is equivalent to one with a zero value. + +9.6 Delay Statements, Duration, and Time + +13 December 2012 228 + + Ada Reference Manual — 2012 Edition + +34 A delay_statement may be executed by the environment task; consequently delay_statements may be executed as +part of the elaboration of a library_item or the execution of the main subprogram. Such statements delay the environment +task (see 10.2). + +35 A delay_statement is an abort completion point and a potentially blocking operation, even if the task is not actually +blocked. + +36 There is no necessary relationship between System.Tick (the resolution of the clock of package Calendar) and +Duration'Small (the small of type Duration). + +37 Additional requirements associated with delay_statements are given in D.9, “Delay Accuracy”. + +Example of a relative delay statement: + +delay 3.0; -- delay 3.0 seconds + +Example of a periodic task: + +Examples + +declare + use Ada.Calendar; + Next_Time : Time := Clock + Period; + -- Period is a global constant of type Duration +begin + loop -- repeated every Period seconds + delay until Next_Time; + ... -- perform some actions + Next_Time := Next_Time + Period; + end loop; +end; + +9.6.1 Formatting, Time Zones, and other operations for Time + +The following language-defined library packages exist: + +Static Semantics + +package Ada.Calendar.Time_Zones is + -- Time zone manipulation: + type Time_Offset is range -28*60 .. 28*60; + Unknown_Zone_Error : exception; + function UTC_Time_Offset (Date : Time := Clock) return Time_Offset; +end Ada.Calendar.Time_Zones; + +package Ada.Calendar.Arithmetic is + -- Arithmetic on days: + type Day_Count is range + -366*(1+Year_Number'Last - Year_Number'First) + .. + 366*(1+Year_Number'Last - Year_Number'First); + subtype Leap_Seconds_Count is Integer range -2047 .. 2047; + procedure Difference (Left, Right : in Time; + Days : out Day_Count; + Seconds : out Duration; + Leap_Seconds : out Leap_Seconds_Count); + function "+" (Left : Time; Right : Day_Count) return Time; + function "+" (Left : Day_Count; Right : Time) return Time; + function "-" (Left : Time; Right : Day_Count) return Time; + function "-" (Left, Right : Time) return Day_Count; + +33 + +34 + +35 + +36 + +37 + +38 + +39 + +40 + +1/2 + +2/2 + +3/2 + +4/2 + +5/2 + +6/2 + +7/2 + +8/2 + +9/2 + +10/2 + +11/2 + +12/2 + +13/2 + +229 13 December 2012 + +Delay Statements, Duration, and Time 9.6 + + + 14/2 + +15/2 + +16/2 + +17/2 + +18/2 + +19/2 + +20/2 + +21/2 + +22/2 + +23/2 + +24/2 + +25/2 + +26/2 + +27/2 + +28/2 + +29/2 + +30/2 + +31/2 + +Ada Reference Manual — 2012 Edition + +end Ada.Calendar.Arithmetic; + +with Ada.Calendar.Time_Zones; +package Ada.Calendar.Formatting is + -- Day of the week: + type Day_Name is (Monday, Tuesday, Wednesday, Thursday, + Friday, Saturday, Sunday); + function Day_of_Week (Date : Time) return Day_Name; + -- Hours:Minutes:Seconds access: + subtype Hour_Number is Natural range 0 .. 23; + subtype Minute_Number is Natural range 0 .. 59; + subtype Second_Number is Natural range 0 .. 59; + subtype Second_Duration is Day_Duration range 0.0 .. 1.0; + function Year (Date : Time; + Time_Zone : Time_Zones.Time_Offset := 0) + return Year_Number; + function Month (Date : Time; + Time_Zone : Time_Zones.Time_Offset := 0) + return Month_Number; + function Day (Date : Time; + Time_Zone : Time_Zones.Time_Offset := 0) + return Day_Number; + function Hour (Date : Time; + Time_Zone : Time_Zones.Time_Offset := 0) + return Hour_Number; + function Minute (Date : Time; + Time_Zone : Time_Zones.Time_Offset := 0) + return Minute_Number; + function Second (Date : Time) + return Second_Number; + function Sub_Second (Date : Time) + return Second_Duration; + function Seconds_Of (Hour : Hour_Number; + Minute : Minute_Number; + Second : Second_Number := 0; + Sub_Second : Second_Duration := 0.0) + return Day_Duration; + procedure Split (Seconds : in Day_Duration; + Hour : out Hour_Number; + Minute : out Minute_Number; + Second : out Second_Number; + Sub_Second : out Second_Duration); + function Time_Of (Year : Year_Number; + Month : Month_Number; + Day : Day_Number; + Hour : Hour_Number; + Minute : Minute_Number; + Second : Second_Number; + Sub_Second : Second_Duration := 0.0; + Leap_Second: Boolean := False; + Time_Zone : Time_Zones.Time_Offset := 0) + return Time; + function Time_Of (Year : Year_Number; + Month : Month_Number; + Day : Day_Number; + Seconds : Day_Duration := 0.0; + Leap_Second: Boolean := False; + Time_Zone : Time_Zones.Time_Offset := 0) + return Time; + +9.6.1 Formatting, Time Zones, and other operations for Time + +13 December 2012 230 + + + Ada Reference Manual — 2012 Edition + + procedure Split (Date : in Time; + Year : out Year_Number; + Month : out Month_Number; + Day : out Day_Number; + Hour : out Hour_Number; + Minute : out Minute_Number; + Second : out Second_Number; + Sub_Second : out Second_Duration; + Time_Zone : in Time_Zones.Time_Offset := 0); + procedure Split (Date : in Time; + Year : out Year_Number; + Month : out Month_Number; + Day : out Day_Number; + Hour : out Hour_Number; + Minute : out Minute_Number; + Second : out Second_Number; + Sub_Second : out Second_Duration; + Leap_Second: out Boolean; + Time_Zone : in Time_Zones.Time_Offset := 0); + procedure Split (Date : in Time; + Year : out Year_Number; + Month : out Month_Number; + Day : out Day_Number; + Seconds : out Day_Duration; + Leap_Second: out Boolean; + Time_Zone : in Time_Zones.Time_Offset := 0); + -- Simple image and value: + function Image (Date : Time; + Include_Time_Fraction : Boolean := False; + Time_Zone : Time_Zones.Time_Offset := 0) return String; + function Value (Date : String; + Time_Zone : Time_Zones.Time_Offset := 0) return Time; + function Image (Elapsed_Time : Duration; + Include_Time_Fraction : Boolean := False) return String; + function Value (Elapsed_Time : String) return Duration; +end Ada.Calendar.Formatting; + +Type Time_Offset represents the number of minutes difference between the implementation-defined time +zone used by Calendar and another time zone. + +function UTC_Time_Offset (Date : Time := Clock) return Time_Offset; + +Returns, as a number of minutes, the result of subtracting the implementation-defined time zone +of Calendar from UTC time, at the time Date. If the time zone of the Calendar implementation is +unknown, then Unknown_Zone_Error is raised. + +procedure Difference (Left, Right : in Time; + Days : out Day_Count; + Seconds : out Duration; + Leap_Seconds : out Leap_Seconds_Count); + +Returns the difference between Left and Right. Days is the number of days of difference, +Seconds is the remainder seconds of difference excluding leap seconds, and Leap_Seconds is the +number of leap seconds. If Left < Right, then Seconds <= 0.0, Days <= 0, and Leap_Seconds <= +0. Otherwise, all values are nonnegative. The absolute value of Seconds is always less than +86_400.0. For the returned values, if Days = 0, then Seconds + Duration(Leap_Seconds) = +Calendar."–" (Left, Right). + +32/2 + +33/2 + +34/2 + +35/2 + +36/2 + +37/2 + +38/2 + +39/2 + +40/2 + +41/2 + +42/3 + +43/2 + +44/2 + +231 13 December 2012 + +Formatting, Time Zones, and other operations for Time 9.6.1 + + Ada Reference Manual — 2012 Edition + +function "+" (Left : Time; Right : Day_Count) return Time; +function "+" (Left : Day_Count; Right : Time) return Time; + +Adds a number of days to a time value. Time_Error is raised if the result is not representable as a +value of type Time. + +function "-" (Left : Time; Right : Day_Count) return Time; + +Subtracts a number of days from a time value. Time_Error is raised if the result is not +representable as a value of type Time. + +function "-" (Left, Right : Time) return Day_Count; + +Subtracts two time values, and returns the number of days between them. This is the same value +that Difference would return in Days. + +function Day_of_Week (Date : Time) return Day_Name; + +Returns the day of the week for Time. This is based on the Year, Month, and Day values of +Time. + +function Year (Date : Time; + Time_Zone : Time_Zones.Time_Offset := 0) + return Year_Number; + +Returns the year for Date, as appropriate for the specified time zone offset. + +function Month (Date : Time; + Time_Zone : Time_Zones.Time_Offset := 0) + return Month_Number; + +Returns the month for Date, as appropriate for the specified time zone offset. + +function Day (Date : Time; + Time_Zone : Time_Zones.Time_Offset := 0) + return Day_Number; + +Returns the day number for Date, as appropriate for the specified time zone offset. + +function Hour (Date : Time; + Time_Zone : Time_Zones.Time_Offset := 0) + return Hour_Number; + +Returns the hour for Date, as appropriate for the specified time zone offset. + +function Minute (Date : Time; + Time_Zone : Time_Zones.Time_Offset := 0) + return Minute_Number; + +Returns the minute within the hour for Date, as appropriate for the specified time zone offset. + +function Second (Date : Time) + return Second_Number; + +Returns the second within the hour and minute for Date. + +function Sub_Second (Date : Time) + return Second_Duration; + +Returns the fraction of second for Date (this has the same accuracy as Day_Duration). The value +returned is always less than 1.0. + +45/2 + +46/2 + +47/2 + +48/2 + +49/2 + +50/2 + +51/2 + +52/2 + +53/2 + +54/2 + +55/2 + +56/2 + +57/2 + +58/2 + +59/2 + +60/2 + +61/2 + +62/2 + +63/2 + +64/2 + +65/2 + +66/2 + +9.6.1 Formatting, Time Zones, and other operations for Time + +13 December 2012 232 + + Ada Reference Manual — 2012 Edition + +function Seconds_Of (Hour : Hour_Number; + Minute : Minute_Number; + Second : Second_Number := 0; + Sub_Second : Second_Duration := 0.0) + return Day_Duration; + +Returns a Day_Duration value for the combination of the given Hour, Minute, Second, and +Sub_Second. This value can be used in Calendar.Time_Of as well as the argument to +Calendar."+" and Calendar."–". If Seconds_Of is called with a Sub_Second value of 1.0, the +value returned is equal to the value of Seconds_Of for the next second with a Sub_Second value +of 0.0. + +procedure Split (Seconds : in Day_Duration; + Hour : out Hour_Number; + Minute : out Minute_Number; + Second : out Second_Number; + Sub_Second : out Second_Duration); + +Splits Seconds into Hour, Minute, Second and Sub_Second in such a way that the resulting +values all belong to their respective subtypes. The value returned in the Sub_Second parameter +is always less than 1.0. If Seconds = 86400.0, Split propagates Time_Error. + +function Time_Of (Year : Year_Number; + Month : Month_Number; + Day : Day_Number; + Hour : Hour_Number; + Minute : Minute_Number; + Second : Second_Number; + Sub_Second : Second_Duration := 0.0; + Leap_Second: Boolean := False; + Time_Zone : Time_Zones.Time_Offset := 0) + return Time; + +If Leap_Second is False, returns a Time built from the date and time values, relative to the +specified time zone offset. If Leap_Second is True, returns the Time that represents the time +within the leap second that is one second later than the time specified by the other parameters. +Time_Error is raised if the parameters do not form a proper date or time. If Time_Of is called +with a Sub_Second value of 1.0, the value returned is equal to the value of Time_Of for the next +second with a Sub_Second value of 0.0. + +function Time_Of (Year : Year_Number; + Month : Month_Number; + Day : Day_Number; + Seconds : Day_Duration := 0.0; + Leap_Second: Boolean := False; + Time_Zone : Time_Zones.Time_Offset := 0) + return Time; + +If Leap_Second is False, returns a Time built from the date and time values, relative to the +specified time zone offset. If Leap_Second is True, returns the Time that represents the time +within the leap second that is one second later than the time specified by the other parameters. +Time_Error is raised if the parameters do not form a proper date or time. If Time_Of is called +with a Seconds value of 86_400.0, the value returned is equal to the value of Time_Of for the +next day with a Seconds value of 0.0. + +67/2 + +68/2 + +69/2 + +70/3 + +71/2 + +72/2 + +73/2 + +74/2 + +233 13 December 2012 + +Formatting, Time Zones, and other operations for Time 9.6.1 + + Ada Reference Manual — 2012 Edition + +75/2 + +76/2 + +77/2 + +78/2 + +79/2 + +80/2 + +81/2 + +82/2 + +procedure Split (Date : in Time; + Year : out Year_Number; + Month : out Month_Number; + Day : out Day_Number; + Hour : out Hour_Number; + Minute : out Minute_Number; + Second : out Second_Number; + Sub_Second : out Second_Duration; + Leap_Second: out Boolean; + Time_Zone : in Time_Zones.Time_Offset := 0); + +If Date does not represent a time within a leap second, splits Date into its constituent parts (Year, +Month, Day, Hour, Minute, Second, Sub_Second), relative to the specified time zone offset, and +sets Leap_Second to False. If Date represents a time within a leap second, set the constituent +parts to values corresponding to a time one second earlier than that given by Date, relative to the +specified time zone offset, and sets Leap_Seconds to True. The value returned in the +Sub_Second parameter is always less than 1.0. + +procedure Split (Date : in Time; + Year : out Year_Number; + Month : out Month_Number; + Day : out Day_Number; + Hour : out Hour_Number; + Minute : out Minute_Number; + Second : out Second_Number; + Sub_Second : out Second_Duration; + Time_Zone : in Time_Zones.Time_Offset := 0); + +Splits Date into its constituent parts (Year, Month, Day, Hour, Minute, Second, Sub_Second), +relative to the specified time zone offset. The value returned in the Sub_Second parameter is +always less than 1.0. + +procedure Split (Date : in Time; + Year : out Year_Number; + Month : out Month_Number; + Day : out Day_Number; + Seconds : out Day_Duration; + Leap_Second: out Boolean; + Time_Zone : in Time_Zones.Time_Offset := 0); + +If Date does not represent a time within a leap second, splits Date into its constituent parts (Year, +Month, Day, Seconds), relative to the specified time zone offset, and sets Leap_Second to False. +If Date represents a time within a leap second, set the constituent parts to values corresponding +to a time one second earlier than that given by Date, relative to the specified time zone offset, +and sets Leap_Seconds to True. The value returned in the Seconds parameter is always less than +86_400.0. + +function Image (Date : Time; + Include_Time_Fraction : Boolean := False; + Time_Zone : Time_Zones.Time_Offset := 0) return String; + +Returns a string form of the Date relative to the given Time_Zone. The format is "Year-Month- +Day Hour:Minute:Second", where the Year is a 4-digit value, and all others are 2-digit values, of +the functions defined in Calendar and Calendar.Formatting, including a leading zero, if needed. +The separators between the values are a minus, another minus, a colon, and a single space +is True, the integer part of +between +Sub_Seconds*100 is suffixed to the string as a point followed by a 2-digit value. + +the Day and Hour. If Include_Time_Fraction + +9.6.1 Formatting, Time Zones, and other operations for Time + +13 December 2012 234 + + Ada Reference Manual — 2012 Edition + +function Value (Date : String; + Time_Zone : Time_Zones.Time_Offset := 0) return Time; + +Returns a Time value for the image given as Date, relative to the given time zone. +Constraint_Error is raised if the string is not formatted as described for Image, or the function +cannot interpret the given string as a Time value. + +function Image (Elapsed_Time : Duration; + Include_Time_Fraction : Boolean := False) return String; + +Returns a string form of the Elapsed_Time. The format is "Hour:Minute:Second", where all +values are 2-digit values, including a leading zero, if needed. The separators between the values +are colons. If Include_Time_Fraction is True, the integer part of Sub_Seconds*100 is suffixed to +the string as a point followed by a 2-digit value. If Elapsed_Time < 0.0, the result is Image (abs +Elapsed_Time, Include_Time_Fraction) prefixed with a minus sign. If abs Elapsed_Time +represents 100 hours or more, the result is implementation-defined. + +function Value (Elapsed_Time : String) return Duration; + +Returns a Duration value for the image given as Elapsed_Time. Constraint_Error is raised if the +string is not formatted as described for Image, or the function cannot interpret the given string as +a Duration value. + +An implementation should support leap seconds if the target system supports them. If leap seconds are not +supported, Difference should return zero for Leap_Seconds, Split should return False for Leap_Second, +and Time_Of should raise Time_Error if Leap_Second is True. + +Implementation Advice + +NOTES +38 The implementation-defined time zone of package Calendar may, but need not, be the local time zone. +UTC_Time_Offset always returns the difference relative to the implementation-defined time zone of package Calendar. If +UTC_Time_Offset does not raise Unknown_Zone_Error, UTC time can be safely calculated (within the accuracy of the +underlying time-base). + +39 Calling Split on the results of subtracting Duration(UTC_Time_Offset*60) from Clock provides the components +(hours, minutes, and so on) of the UTC time. In the United States, for example, UTC_Time_Offset will generally be +negative. + +9.7 Select Statements + +There are four forms of the select_statement. One form provides a selective wait for one or more +select_alternatives. Two provide timed and conditional entry calls. The fourth provides asynchronous +transfer of control. + +Syntax + +select_statement ::= + selective_accept + | timed_entry_call + | conditional_entry_call + | asynchronous_select + +83/2 + +84/2 + +85/2 + +86/2 + +87/2 + +88/2 + +89/2 + +90/2 + +91/2 + +1 + +2 + +235 13 December 2012 + +Formatting, Time Zones, and other operations for Time 9.6.1 + + 3 + +4 + +1 + +2 + +3 + +4 + +5 + +6 + +7 + +8 + +9 + +10 + +11 + +12 + +13 + +14 + +Examples + +Ada Reference Manual — 2012 Edition + +Example of a select statement: + +select + accept Driver_Awake_Signal; +or + delay 30.0*Seconds; + Stop_The_Train; +end select; + +9.7.1 Selective Accept + +This form of the select_statement allows a combination of waiting for, and selecting from, one or more +alternatives. The selection may depend on conditions associated with each alternative of the +selective_accept. + +Syntax + +selective_accept ::= + select + [guard] + select_alternative +{ or + [guard] + select_alternative } +[ else + sequence_of_statements ] + end select; + +guard ::= when condition => + +select_alternative ::= + accept_alternative + | delay_alternative + | terminate_alternative + +accept_alternative ::= + accept_statement [sequence_of_statements] + +delay_alternative ::= + delay_statement [sequence_of_statements] + +terminate_alternative ::= terminate; + +A selective_accept shall contain at least one accept_alternative. In addition, it can contain: + +• a terminate_alternative (only one); or +• one or more delay_alternatives; or +• an else part (the reserved word else followed by a sequence_of_statements). + +These three possibilities are mutually exclusive. + +If a selective_accept contains more than one delay_alternative, then all shall be delay_relative_- +statements, or all shall be delay_until_statements for the same time type. + +Legality Rules + +A select_alternative is said to be open if it is not immediately preceded by a guard, or if the condition of +its guard evaluates to True. It is said to be closed otherwise. + +Dynamic Semantics + +9.7 Select Statements + +13 December 2012 236 + + Ada Reference Manual — 2012 Edition + +For the execution of a selective_accept, any guard conditions are evaluated; open alternatives are thus +determined. For an open delay_alternative, the delay_expression is also evaluated. Similarly, for an open +accept_alternative for an entry of a family, the entry_index is also evaluated. These evaluations are +performed in an arbitrary order, except that a delay_expression or entry_index is not evaluated until after +evaluating the corresponding condition, if any. Selection and execution of one open alternative, or of the +else part, then completes the execution of the selective_accept; the rules for this selection are described +below. + +Open accept_alternatives are first considered. Selection of one such alternative takes place immediately if +the corresponding entry already has queued calls. If several alternatives can thus be selected, one of them +is selected according to the entry queuing policy in effect (see 9.5.3 and D.4). When such an alternative is +selected, the selected call is removed from its entry queue and the handled_sequence_of_statements (if +any) of the corresponding accept_statement is executed; after the rendezvous completes any subsequent +sequence_of_statements of the alternative is executed. If no selection is immediately possible (in the +above sense) and there is no else part, the task blocks until an open alternative can be selected. + +Selection of the other forms of alternative or of an else part is performed as follows: + +• An open delay_alternative is selected when its expiration time is reached if no accept_- +alternative or other delay_alternative can be selected prior to the expiration time. If several +delay_alternatives have this same expiration time, one of them is selected according to the +queuing policy in effect (see D.4); the default queuing policy chooses arbitrarily among the +delay_alternatives whose expiration time has passed. + +• The else part is selected and its sequence_of_statements is executed if no accept_alternative + +can immediately be selected; in particular, if all alternatives are closed. + +• An open terminate_alternative is selected if the conditions stated at the end of subclause 9.3 are + +satisfied. + +The exception Program_Error is raised if all alternatives are closed and there is no else part. + +NOTES +40 A selective_accept is allowed to have several open delay_alternatives. A selective_accept is allowed to have several +open accept_alternatives for the same entry. + +Example of a task body with a selective accept: + +Examples + +task body Server is + Current_Work_Item : Work_Item; +begin + loop + select + accept Next_Work_Item(WI : in Work_Item) do + Current_Work_Item := WI; + end; + Process_Work_Item(Current_Work_Item); + or + accept Shut_Down; + exit; -- Premature shut down requested + or + terminate; -- Normal shutdown at end of scope + end select; + end loop; +end Server; + +15 + +16 + +17 + +18 + +19 + +20/3 + +21 + +22 + +23 + +24 + +237 13 December 2012 + +Selective Accept 9.7.1 + + Ada Reference Manual — 2012 Edition + +9.7.2 Timed Entry Calls + +A timed_entry_call issues an entry call that is cancelled if the call (or a requeue-with-abort of the call) is +not selected before the expiration time is reached. A procedure call may appear rather than an entry call +for cases where the procedure might be implemented by an entry. + +Syntax + +timed_entry_call ::= + select + entry_call_alternative + or + delay_alternative + end select; + +entry_call_alternative ::= + procedure_or_entry_call [sequence_of_statements] + +procedure_or_entry_call ::= + procedure_call_statement | entry_call_statement + +Legality Rules + +If a procedure_call_statement is used for a procedure_or_entry_call, the procedure_name or +procedure_prefix of the procedure_call_statement shall statically denote an entry renamed as a procedure +or (a view of) a primitive subprogram of a limited interface whose first parameter is a controlling +parameter (see 3.9.2). + +Dynamic Semantics + +For the execution of a timed_entry_call, the entry_name, procedure_name, or procedure_prefix, and any +actual parameters are evaluated, as for a simple entry call (see 9.5.3) or procedure call (see 6.4). The +expiration time (see 9.6) for the call is determined by evaluating the delay_expression of the +delay_alternative. If the call is an entry call or a call on a procedure implemented by an entry, the entry +call is then issued. Otherwise, the call proceeds as described in 6.4 for a procedure call, followed by the +sequence_of_statements of the entry_call_alternative; the sequence_of_statements of the delay_- +alternative is ignored. + +If the call is queued (including due to a requeue-with-abort), and not selected before the expiration time is +reached, an attempt to cancel the call is made. If the call completes due to the cancellation, the optional +sequence_of_statements of the delay_alternative is executed; if the entry call completes normally, the +optional sequence_of_statements of the entry_call_alternative is executed. + +Examples + +Example of a timed entry call: + +select + Controller.Request(Medium)(Some_Item); +or + delay 45.0; + -- controller too busy, try something else +end select; + +1/2 + +2 + +3/2 + +3.1/2 + +3.2/2 + +4/2 + +5 + +6 + +7 + +9.7.2 Timed Entry Calls + +13 December 2012 238 + + Ada Reference Manual — 2012 Edition + +9.7.3 Conditional Entry Calls + +A conditional_entry_call issues an entry call that is then cancelled if it is not selected immediately (or if a +requeue-with-abort of the call is not selected immediately). A procedure call may appear rather than an +entry call for cases where the procedure might be implemented by an entry. + +1/2 + +Syntax + +conditional_entry_call ::= + select + entry_call_alternative + else + sequence_of_statements + end select; + +Dynamic Semantics + +The execution of a conditional_entry_call is defined to be equivalent to the execution of a timed_entry_- +call with a delay_alternative specifying an immediate expiration time and the same sequence_of_- +statements as given after the reserved word else. + +NOTES +41 A conditional_entry_call may briefly increase the Count attribute of the entry, even if the conditional call is not +selected. + +Examples + +Example of a conditional entry call: + +procedure Spin(R : in Resource) is +begin + loop + select + R.Seize; + return; + else + null; -- busy waiting + end select; + end loop; +end; + +9.7.4 Asynchronous Transfer of Control + +An asynchronous select_statement provides asynchronous transfer of control upon completion of an entry +call or the expiration of a delay. + +Syntax + +asynchronous_select ::= + select + triggering_alternative + then abort + abortable_part + end select; + +triggering_alternative ::= triggering_statement [sequence_of_statements] + +triggering_statement ::= procedure_or_entry_call | delay_statement + +abortable_part ::= sequence_of_statements + +239 13 December 2012 + +Conditional Entry Calls 9.7.3 + +2 + +3 + +4 + +5 + +6 + +1 + +2 + +3 + +4/2 + +5 + + 6/2 + +7 + +8 + +9 + +10 + +11 + +12 + +13 + +1 + +2 + +Ada Reference Manual — 2012 Edition + +Dynamic Semantics + +For the execution of an asynchronous_select whose triggering_statement is a procedure_or_entry_call, +the entry_name, procedure_name, or procedure_prefix, and actual parameters are evaluated as for a +simple entry call (see 9.5.3) or procedure call (see 6.4). If the call is an entry call or a call on a procedure +implemented by an entry, the entry call is issued. If the entry call is queued (or requeued-with-abort), then +the abortable_part is executed. If the entry call is selected immediately, and never requeued-with-abort, +then the abortable_part is never started. If the call is on a procedure that is not implemented by an entry, +the call proceeds as described in 6.4, followed by the sequence_of_statements of the triggering_- +alternative; the abortable_part is never started. + +For the execution of an asynchronous_select whose triggering_statement is a delay_statement, the +delay_expression is evaluated and the expiration time is determined, as for a normal delay_statement. If +the expiration time has not already passed, the abortable_part is executed. + +If the abortable_part completes and is left prior to completion of the triggering_statement, an attempt to +cancel the triggering_statement is made. If the attempt to cancel succeeds (see 9.5.3 and 9.6), the +asynchronous_select is complete. + +If the triggering_statement completes other than due to cancellation, the abortable_part is aborted (if +started but not yet completed — see 9.8). If the triggering_statement completes normally, the optional +sequence_of_statements of the triggering_alternative is executed after the abortable_part is left. + +Example of a main command loop for a command interpreter: + +Examples + +loop + select + Terminal.Wait_For_Interrupt; + Put_Line("Interrupted"); + then abort + -- This will be abandoned upon terminal interrupt + Put_Line("-> "); + Get_Line(Command, Last); + Process_Command(Command(1..Last)); + end select; +end loop; + +Example of a time-limited calculation: + +select + delay 5.0; + Put_Line("Calculation does not converge"); +then abort + -- This calculation should finish in 5.0 seconds; + -- if not, it is assumed to diverge. + Horribly_Complicated_Recursive_Function(X, Y); +end select; + +9.8 Abort of a Task - Abort of a Sequence of Statements + +An abort_statement causes one or more tasks to become abnormal, thus preventing any further interaction +with such tasks. The completion of the triggering_statement of an asynchronous_select causes a +sequence_of_statements to be aborted. + +abort_statement ::= abort task_name {, task_name}; + +Syntax + +9.7.4 Asynchronous Transfer of Control + +13 December 2012 240 + + Ada Reference Manual — 2012 Edition + +Each task_name is expected to be of any task type; they need not all be of the same task type. + +Name Resolution Rules + +Dynamic Semantics + +For the execution of an abort_statement, the given task_names are evaluated in an arbitrary order. Each +named task is then aborted, which consists of making the task abnormal and aborting the execution of the +corresponding task_body, unless it is already completed. + +When the execution of a construct is aborted (including that of a task_body or of a sequence_of_- +statements), the execution of every construct included within the aborted execution is also aborted, except +for executions included within the execution of an abort-deferred operation; the execution of an abort- +deferred operation continues to completion without being affected by the abort; the following are the +abort-deferred operations: +• a protected action; +• waiting for an entry call to complete (after having initiated the attempt to cancel it — see + +below); + +• waiting for the termination of dependent tasks; +• + +the execution of an Initialize procedure as the last step of the default initialization of a controlled +object; + +the execution of a Finalize procedure as part of the finalization of a controlled object; + +• +• an assignment operation to an object with a controlled part. + +The last three of these are discussed further in 7.6. + +When a master is aborted, all tasks that depend on that master are aborted. + +The order in which tasks become abnormal as the result of an abort_statement or the abort of a +sequence_of_statements is not specified by the language. + +If the execution of an entry call is aborted, an immediate attempt is made to cancel the entry call (see +9.5.3). If the execution of a construct is aborted at a time when the execution is blocked, other than for an +entry call, at a point that is outside the execution of an abort-deferred operation, then the execution of the +construct completes immediately. For an abort due to an abort_statement, these immediate effects occur +before the execution of the abort_statement completes. Other than for these immediate cases, the +execution of a construct that is aborted does not necessarily complete before the abort_statement +completes. However, the execution of the aborted construct completes no later than its next abort +completion point (if any) that occurs outside of an abort-deferred operation; the following are abort +completion points for an execution: + +• +• +• + +• + +the point where the execution initiates the activation of another task; + +the end of the activation of a task; + +the start or end of the execution of an entry call, accept_statement, delay_statement, or +abort_statement; + +the start of the execution of a select_statement, or of the sequence_of_statements of an +exception_handler. + +3 + +4 + +5 + +6 + +7 + +8 + +9 + +10 + +11 + +12 + +13 + +14 + +15 + +16 + +17 + +18 + +19 + +An attempt to execute an asynchronous_select as part of the execution of an abort-deferred operation is a +bounded error. Similarly, an attempt to create a task that depends on a master that is included entirely + +20/3 + +Bounded (Run-Time) Errors + +241 13 December 2012 + +Abort of a Task - Abort of a Sequence of Statements 9.8 + + Ada Reference Manual — 2012 Edition + +within the execution of an abort-deferred operation is a bounded error. In both cases, Program_Error is +raised if the error is detected by the implementation; otherwise, the operations proceed as they would +outside an abort-deferred operation, except that an abort of the abortable_part or the created task might or +might not have an effect. + +If an assignment operation completes prematurely due to an abort, the assignment is said to be disrupted; +the target of the assignment or its parts can become abnormal, and certain subsequent uses of the object +can be erroneous, as explained in 13.9.1. + +Erroneous Execution + +NOTES +42 An abort_statement should be used only in situations requiring unconditional termination. + +43 A task is allowed to abort any task it can name, including itself. + +44 Additional requirements associated with abort are given in D.6, “Preemptive Abort”. + +9.9 Task and Entry Attributes + +Dynamic Semantics + +For a prefix T that is of a task type (after any implicit dereference), the following attributes are defined: + +T'Callable + +Yields the value True when the task denoted by T is callable, and False otherwise; a task is +callable unless it is completed or abnormal. The value of this attribute is of the predefined +type Boolean. + +T'Terminated Yields the value True if the task denoted by T is terminated, and False otherwise. The value + +of this attribute is of the predefined type Boolean. + +For a prefix E that denotes an entry of a task or protected unit, the following attribute is defined. This +attribute is only allowed within the body of the task or protected unit, but excluding, in the case of an entry +of a task unit, within any program unit that is, itself, inner to the body of the task unit. + +E'Count + +Yields the number of calls presently queued on the entry E of the current instance of the +unit. The value of this attribute is of the type universal_integer. + +NOTES +45 For the Count attribute, the entry can be either a single entry or an entry of a family. The name of the entry or entry +family can be either a direct_name or an expanded name. + +46 Within task units, algorithms interrogating the attribute E'Count should take precautions to allow for the increase of +the value of this attribute for incoming entry calls, and its decrease, for example with timed_entry_calls. Also, a +conditional_entry_call may briefly increase this value, even if the conditional call is not accepted. + +47 Within protected units, algorithms interrogating the attribute E'Count in the entry_barrier for the entry E should take +precautions to allow for the evaluation of the condition of the barrier both before and after queuing a given caller. + +21 + +22 + +23 + +24 + +1 + +2 + +3 + +4 + +5 + +6 + +7 + +8 + +9.10 Shared Variables + +Static Semantics + +1/3 + +If two different objects, including nonoverlapping parts of the same object, are independently addressable, +they can be manipulated concurrently by two different tasks without synchronization. Any two +nonoverlapping objects are independently addressable if either object is specified as independently +addressable (see C.6). Otherwise, two nonoverlapping objects are independently addressable except when +they are both parts of a composite object for which a nonconfirming value is specified for any of the + +9.8 Abort of a Task - Abort of a Sequence of Statements + +13 December 2012 242 + + Ada Reference Manual — 2012 Edition + +following representation aspects: (record) Layout, Component_Size, Pack, Atomic, or Convention; in this +case it is unspecified whether the parts are independently addressable. + +Dynamic Semantics + +Separate tasks normally proceed independently and concurrently with one another. However, task +interactions can be used to synchronize the actions of two or more tasks to allow, for example, meaningful +communication by the direct updating and reading of variables shared between the tasks. The actions of +two different tasks are synchronized in this sense when an action of one task signals an action of the other +task; an action A1 is defined to signal an action A2 under the following circumstances: + +• If A1 and A2 are part of the execution of the same task, and the language rules require A1 to be + +performed before A2; + +• If A1 is the action of an activator that initiates the activation of a task, and A2 is part of the + +execution of the task that is activated; + +• If A1 is part of the activation of a task, and A2 is the action of waiting for completion of the + +activation; + +• If A1 is part of the execution of a task, and A2 is the action of waiting for the termination of the + +task; + +2 + +3 + +4 + +5 + +6 + +• If A1 is the termination of a task T, and A2 is either an evaluation of the expression +T'Terminated that results in True, or a call to Ada.Task_Identification.Is_Terminated with an +actual parameter that identifies T and a result of True (see C.7.1); + +6.1/3 + +• If A1 is the action of issuing an entry call, and A2 is part of the corresponding execution of the + +7/3 + +appropriate entry_body or accept_statement; + +• If A1 is part of the execution of an accept_statement or entry_body, and A2 is the action of + +returning from the corresponding entry call; + +• If A1 is part of the execution of a protected procedure body or entry_body for a given protected + +object, and A2 is part of a later execution of an entry_body for the same protected object; + +• If A1 signals some action that in turn signals A2. + +Erroneous Execution + +Given an action of assigning to an object, and an action of reading or updating a part of the same object (or +of a neighboring object if the two are not independently addressable), then the execution of the actions is +erroneous unless the actions are sequential. Two actions are sequential if one of the following is true: + +• One action signals the other; +• Both actions occur as part of the execution of the same task; +• Both actions occur as part of protected actions on the same protected object, and at most one of + +the actions is part of a call on a protected function of the protected object. + +8 + +9 + +10 + +11 + +12 + +13 + +14 + +Aspect Atomic or aspect Atomic_Components may also be specified to ensure that certain reads and +updates are sequential — see C.6. + +15/3 + +243 13 December 2012 + +Shared Variables 9.10 + + Ada Reference Manual — 2012 Edition + +9.11 Example of Tasking and Synchronization + +Examples + +The following example defines a buffer protected object to smooth variations between the speed of output +of a producing task and the speed of input of some consuming task. For instance, the producing task might +have the following structure: +task Producer; +task body Producer is + Person : Person_Name; -- see 3.10.1 +begin + loop + ... -- simulate arrival of the next customer + Buffer.Append_Wait(Person); + exit when Person = null; + end loop; +end Producer; + +and the consuming task might have the following structure: + +task Consumer; +task body Consumer is + Person : Person_Name; +begin + loop + Buffer.Remove_First_Wait(Person); + exit when Person = null; + ... -- simulate serving a customer + end loop; +end Consumer; + +The buffer object contains an internal array of person names managed in a round-robin fashion. The array +has two indices, an In_Index denoting the index for the next input person name and an Out_Index denoting +the index for the next output person name. + +The Buffer is defined as an extension of the Synchronized_Queue interface (see 3.9.4), and as such +promises to implement the abstraction defined by that interface. By doing so, the Buffer can be passed to +the Transfer class-wide operation defined for objects of a type covered by Queue'Class. + +protected Buffer is new Synchronized_Queue with -- see 3.9.4 + entry Append_Wait(Person : in Person_Name); + entry Remove_First_Wait(Person : out Person_Name); + function Cur_Count return Natural; + function Max_Count return Natural; + procedure Append(Person : in Person_Name); + procedure Remove_First(Person : out Person_Name); +private + Pool : Person_Name_Array(1 .. 100); + Count : Natural := 0; + In_Index, Out_Index : Positive := 1; +end Buffer; +protected body Buffer is + entry Append_Wait(Person : in Person_Name) + when Count < Pool'Length is + begin + Append(Person); + end Append_Wait; + +1 + +2 + +3/2 + +4 + +5 + +6/2 + +7/2 + +7.1/2 + +8/2 + +9/2 + +9.11 Example of Tasking and Synchronization + +13 December 2012 244 + + Ada Reference Manual — 2012 Edition + + procedure Append(Person : in Person_Name) is + begin + if Count = Pool'Length then + raise Queue_Error with "Buffer Full"; -- see 11.3 + end if; + Pool(In_Index) := Person; + In_Index := (In_Index mod Pool'Length) + 1; + Count := Count + 1; + end Append; + entry Remove_First_Wait(Person : out Person_Name) + when Count > 0 is + begin + Remove_First(Person); + end Remove_First_Wait; + procedure Remove_First(Person : out Person_Name) is + begin + if Count = 0 then + raise Queue_Error with "Buffer Empty"; -- see 11.3 + end if; + Person := Pool(Out_Index); + Out_Index := (Out_Index mod Pool'Length) + 1; + Count := Count - 1; + end Remove_First; + function Cur_Count return Natural is + begin + return Buffer.Count; + end Cur_Count; + function Max_Count return Natural is + begin + return Pool'Length; + end Max_Count; +end Buffer; + +9.1/2 + +10/2 + +11/2 + +12/2 + +13/2 + +245 13 December 2012 + +Example of Tasking and Synchronization 9.11 + + Ada Reference Manual — 2012 Edition + +10 Program Structure and Compilation Issues + +The overall structure of programs and the facilities for separate compilation are described in this clause. A +program is a set of partitions, each of which may execute in a separate address space, possibly on a +separate computer. + +As explained below, a partition is constructed from library units. Syntactically, the declaration of a library +unit is a library_item, as is the body of a library unit. An implementation may support a concept of a +program library (or simply, a “library”), which contains library_items and their subunits. Library units +may be organized into a hierarchy of children, grandchildren, and so on. + +This clause has two subclauses: 10.1, “Separate Compilation” discusses compile-time issues related to +separate compilation. 10.2, “Program Execution” discusses issues related to what is traditionally known as +“link time” and “run time” — building and executing partitions. + +10.1 Separate Compilation + +A program unit is either a package, a task unit, a protected unit, a protected entry, a generic unit, or an +explicitly declared subprogram other than an enumeration literal. Certain kinds of program units can be +separately compiled. Alternatively, they can appear physically nested within other program units. + +The text of a program can be submitted to the compiler in one or more compilations. Each compilation is a +succession of compilation_units. A compilation_unit contains either the declaration, the body, or a +renaming of a program unit. The representation for a compilation is implementation-defined. + +A library unit is a separately compiled program unit, and is always a package, subprogram, or generic unit. +Library units may have other (logically nested) library units as children, and may have other program units +physically nested within them. A root library unit, together with its children and grandchildren and so on, +form a subsystem. + +An implementation may impose implementation-defined restrictions on compilations that contain multiple +compilation_units. + +Implementation Permissions + +10.1.1 Compilation Units - Library Units + +A library_item is a compilation unit that is the declaration, body, or renaming of a library unit. Each +library unit (except Standard) has a parent unit, which is a library package or generic library package. A +library unit is a child of its parent unit. The root library units are the children of the predefined library +package Standard. + +Syntax + +compilation ::= {compilation_unit} + +compilation_unit ::= + context_clause library_item + | context_clause subunit + +library_item ::= [private] library_unit_declaration + | library_unit_body + | [private] library_unit_renaming_declaration + +1/3 + +2 + +3/3 + +1 + +2 + +3 + +4 + +1 + +2 + +3 + +4 + +247 13 December 2012 + +Program Structure and Compilation Issues 10 + + 5 + +6 + +7 + +8 + +8.1/2 + +9 + +10 + +11 + +12 + +Ada Reference Manual — 2012 Edition + +library_unit_declaration ::= + subprogram_declaration + | generic_declaration + +| package_declaration +| generic_instantiation + +library_unit_renaming_declaration ::= + package_renaming_declaration + | generic_renaming_declaration + | subprogram_renaming_declaration + +library_unit_body ::= subprogram_body | package_body + +parent_unit_name ::= name + +An overriding_indicator is not allowed in a subprogram_declaration, generic_instantiation, or +subprogram_renaming_declaration that declares a library unit. + +A library unit is a program unit that is declared by a library_item. When a program unit is a library unit, +the prefix “library” is used to refer to it (or “generic library” if generic), as well as to its declaration and +body, as in “library procedure”, “library package_body”, or “generic library package”. The term +compilation unit is used to refer to a compilation_unit. When the meaning is clear from context, the term is +also used to refer to the library_item of a compilation_unit or to the proper_body of a subunit (that is, the +compilation_unit without the context_clause and the separate (parent_unit_name)). + +The parent declaration of a library_item (and of the library unit) is the declaration denoted by the parent_- +unit_name, if any, of the defining_program_unit_name of the library_item. If there is no parent_- +unit_name, the parent declaration is the declaration of Standard, the library_item is a root library_item, +and the library unit (renaming) is a root library unit (renaming). The declaration and body of Standard +itself have no parent declaration. The parent unit of a library_item or library unit is the library unit +declared by its parent declaration. + +The children of a library unit occur immediately within the declarative region of the declaration of the +library unit. The ancestors of a library unit are itself, its parent, its parent's parent, and so on. (Standard is +an ancestor of every library unit.) The descendant relation is the inverse of the ancestor relation. + +A library_unit_declaration or a library_unit_renaming_declaration is private if the declaration is +immediately preceded by the reserved word private; it is otherwise public. A library unit is private or +public according to its declaration. The public descendants of a library unit are the library unit itself, and +the public descendants of its public children. Its other descendants are private descendants. + +12.1/2 + +For each library package_declaration in the environment, there is an implicit declaration of a limited view +of that library package. The limited view of a package contains: + +12.2/3 + +• For each package_declaration occurring immediately within the visible part, a declaration of + +the limited view of that package, with the same defining_program_unit_name. + +12.3/3 + +• For each type_declaration occurring immediately within the visible part that is not an +incomplete_type_declaration, an incomplete view of the type with no discriminant_part; if the +type_declaration is tagged, then the view is a tagged incomplete view. + +12.4/2 + +The limited view of a library package_declaration is private if that library package_declaration is +immediately preceded by the reserved word private. + +12.5/2 + +There is no syntax for declaring limited views of packages, because they are always implicit. The implicit +declaration of a limited view of a library package is not the declaration of a library unit (the library +package_declaration is); nonetheless, it is a library_item. The implicit declaration of the limited view of a +library package forms an (implicit) compilation unit whose context_clause is empty. + +12.6/2 + +A library package_declaration is the completion of the declaration of its limited view. + +10.1.1 Compilation Units - Library Units + +13 December 2012 248 + + Ada Reference Manual — 2012 Edition + +The parent unit of a library_item shall be a library package or generic library package. + +Legality Rules + +If a defining_program_unit_name of a given declaration or body has a parent_unit_name, then the given +declaration or body shall be a library_item. The body of a program unit shall be a library_item if and only +if the declaration of the program unit is a library_item. In a library_unit_renaming_declaration, the (old) +name shall denote a library_item. + +A parent_unit_name (which can be used within a defining_program_unit_name of a library_item and in +the separate clause of a subunit), and each of its prefixes, shall not denote a renaming_declaration. On +in a +library_unit_renaming_declaration +the other hand, a name +nonlimited_with_clause and other places where the name of a library unit is allowed. + +that denotes a + +is allowed + +If a library package is an instance of a generic package, then every child of the library package shall either +be itself an instance or be a renaming of a library unit. + +A child of a generic library package shall either be itself a generic unit or be a renaming of some other +child of the same generic unit. + +A child of a parent generic package shall be instantiated or renamed only within the declarative region of +the parent generic. + +For each child C of some parent generic package P, there is a corresponding declaration C nested +immediately within each instance of P. For the purposes of this rule, if a child C itself has a child D, each +corresponding declaration for C has a corresponding child D. The corresponding declaration for a child +within an instance is visible only within the scope of a with_clause that mentions the (original) child +generic unit. + +A library subprogram shall not override a primitive subprogram. + +The defining name of a function that is a compilation unit shall not be an operator_symbol. + +Static Semantics + +A subprogram_renaming_declaration that is a library_unit_renaming_declaration is a renaming-as- +declaration, not a renaming-as-body. + +There are two kinds of dependences among compilation units: + +• The semantic dependences (see below) are the ones needed to check the compile-time rules +across compilation unit boundaries; a compilation unit depends semantically on the other +compilation units needed to determine its legality. The visibility rules are based on the semantic +dependences. + +• The elaboration dependences (see 10.2) determine the order of elaboration of library_items. + +A library_item depends semantically upon its parent declaration. A subunit depends semantically upon its +parent body. A library_unit_body depends semantically upon the corresponding library_unit_declaration, +if any. The declaration of the limited view of a library package depends semantically upon the declaration +of the limited view of its parent. The declaration of a library package depends semantically upon the +declaration of its limited view. A compilation unit depends semantically upon each library_item mentioned +in a with_clause of the compilation unit. In addition, if a given compilation unit contains an +attribute_reference of a type defined in another compilation unit, then the given compilation unit depends +semantically upon the other compilation unit. The semantic dependence relationship is transitive. + +249 13 December 2012 + +Compilation Units - Library Units 10.1.1 + +13 + +14 + +15/2 + +16 + +17/3 + +18 + +19/2 + +20 + +21 + +22 + +23 + +24 + +25 + +26/2 + + Ada Reference Manual — 2012 Edition + +26.1/2 + +The elaboration of the declaration of the limited view of a package has no effect. + +Dynamic Semantics + +27 + +28 + +29 + +30 + +31 + +32 + +33 + +34 + +NOTES +1 A simple program may consist of a single compilation unit. A compilation need not have any compilation units; for +example, its text can consist of pragmas. + +2 The designator of a library function cannot be an operator_symbol, but a nonlibrary renaming_declaration is allowed +to rename a library function as an operator. Within a partition, two library subprograms are required to have distinct +names and hence cannot overload each other. However, renaming_declarations are allowed to define overloaded names +for such subprograms, and a locally declared subprogram is allowed to overload a library subprogram. The expanded +name Standard.L can be used to denote a root library unit L (unless the declaration of Standard is hidden) since root +library unit declarations occur immediately within the declarative region of package Standard. + +Examples of library units: + +Examples + +package Rational_Numbers.IO is -- public child of Rational_Numbers, see 7.1 + procedure Put(R : in Rational); + procedure Get(R : out Rational); +end Rational_Numbers.IO; +private procedure Rational_Numbers.Reduce(R : in out Rational); + -- private child of Rational_Numbers +with Rational_Numbers.Reduce; -- refer to a private child +package body Rational_Numbers is + ... +end Rational_Numbers; +with Rational_Numbers.IO; use Rational_Numbers; +with Ada.Text_io; -- see A.10 +procedure Main is -- a root library procedure + R : Rational; +begin + R := 5/3; -- construct a rational number, see 7.1 + Ada.Text_IO.Put("The answer is: "); + IO.Put(R); + Ada.Text_IO.New_Line; +end Main; +with Rational_Numbers.IO; +package Rational_IO renames Rational_Numbers.IO; + -- a library unit renaming declaration + +35 + +Each of the above library_items can be submitted to the compiler separately. + +10.1.2 Context Clauses - With Clauses + +A context_clause is used to specify the library_items whose names are needed within a compilation unit. + +context_clause ::= {context_item} + +context_item ::= with_clause | use_clause + +Syntax + +with_clause ::= limited_with_clause | nonlimited_with_clause + +limited_with_clause ::= limited [private] with library_unit_name {, library_unit_name}; + +nonlimited_with_clause ::= [private] with library_unit_name {, library_unit_name}; + +1 + +2 + +3 + +4/2 + +4.1/2 + +4.2/2 + +10.1.1 Compilation Units - Library Units + +13 December 2012 250 + + Ada Reference Manual — 2012 Edition + +Name Resolution Rules + +The scope of a with_clause that appears on a library_unit_declaration or library_unit_renaming_- +declaration consists of the entire declarative region of the declaration, which includes all children and +subunits. The scope of a with_clause that appears on a body consists of the body, which includes all +subunits. + +A library_item (and the corresponding library unit) is named in a with_clause if it is denoted by a +library_unit_name in the with_clause. A library_item (and the corresponding library unit) is mentioned in +a with_clause if it is named in the with_clause or if it is denoted by a prefix in the with_clause. + +Outside its own declarative region, the declaration or renaming of a library unit can be visible only within +the scope of a with_clause that mentions it. The visibility of the declaration or renaming of a library unit +otherwise follows from its placement in the environment. + +Legality Rules + +If a with_clause of a given compilation_unit mentions a private child of some library unit, then the given +compilation_unit shall be one of: + +• +• + +• + +the declaration, body, or subunit of a private descendant of that library unit; + +the body or subunit of a public descendant of that library unit, but not a subprogram body acting +as a subprogram declaration (see 10.1.4); or + +the declaration of a public descendant of that library unit, in which case the with_clause shall +include the reserved word private. + +A name denoting a library_item (or the corresponding declaration for a child of a generic within an +instance — see 10.1.1), if it is visible only due to being mentioned in one or more with_clauses that +include the reserved word private, shall appear only within: + +• a private part; +• a body, but not within the subprogram_specification of a library subprogram body; +• a private descendant of the unit on which one of these with_clauses appear; or +• a pragma within a context clause. + +A library_item mentioned in a limited_with_clause shall be the implicit declaration of the limited view of +a library package, not the declaration of a subprogram, generic unit, generic instance, or a renaming. + +A limited_with_clause shall not appear on a library_unit_body, subunit, or library_unit_renaming_- +declaration. + +A limited_with_clause that names a library package shall not appear: + +• + +in the context_clause for the explicit declaration of the named library package or any of its +descendants; + +• within a context_clause for a library_item that is within the scope of a nonlimited_with_clause + +that mentions the same library package; or + +• within a context_clause for a library_item that is within the scope of a use_clause that names + +an entity declared within the declarative region of the library package. + +NOTES +3 A library_item mentioned in a nonlimited_with_clause of a compilation unit is visible within the compilation unit and +hence acts just like an ordinary declaration. Thus, within a compilation unit that mentions its declaration, the name of a +library package can be given in use_clauses and can be used to form expanded names, a library subprogram can be +called, and instances of a generic library unit can be declared. If a child of a parent generic package is mentioned in a + +5 + +6/2 + +7 + +8/2 + +9/2 + +10/2 + +11/2 + +12/3 + +13/2 + +14/2 + +15/2 + +16/2 + +17/2 + +18/2 + +19/2 + +20/3 + +21/3 + +22/3 + +23/2 + +251 13 December 2012 + +Context Clauses - With Clauses 10.1.2 + + Ada Reference Manual — 2012 Edition + +nonlimited_with_clause, then the corresponding declaration nested within each visible instance is visible within the +compilation unit. Similarly, a library_item mentioned in a limited_with_clause of a compilation unit is visible within the +compilation unit and thus can be used to form expanded names. + +Examples + +package Office is +end Office; +with Ada.Strings.Unbounded; +package Office.Locations is + type Location is new Ada.Strings.Unbounded.Unbounded_String; +end Office.Locations; +limited with Office.Departments; -- types are incomplete +private with Office.Locations; -- only visible in private part +package Office.Employees is + type Employee is private; + function Dept_Of(Emp : Employee) return access Departments.Department; + procedure Assign_Dept(Emp : in out Employee; + Dept : access Departments.Department); + ... +private + type Employee is + record + Dept : access Departments.Department; + Loc : Locations.Location; + ... + end record; +end Office.Employees; +limited with Office.Employees; +package Office.Departments is + type Department is private; + function Manager_Of(Dept : Department) return access Employees.Employee; + procedure Assign_Manager(Dept : in out Department; + Mgr : access Employees.Employee); + ... +end Office.Departments; + +The limited_with_clause may be used to support mutually dependent abstractions that are split across +multiple packages. In this case, an employee is assigned to a department, and a department has a manager +who is an employee. If a with_clause with the reserved word private appears on one library unit and +mentions a second library unit, it provides visibility to the second library unit, but restricts that visibility to +the private part and body of the first unit. The compiler checks that no use is made of the second unit in +the visible part of the first unit. + +10.1.3 Subunits of Compilation Units + +Subunits are like child units, with these (important) differences: subunits support the separate compilation +of bodies only (not declarations); the parent contains a body_stub to indicate the existence and place of +each of its subunits; declarations appearing in the parent's body can be visible within the subunits. + +body_stub ::= +subprogram_body_stub | package_body_stub | task_body_stub | protected_body_stub + +Syntax + +subprogram_body_stub ::= + [overriding_indicator] + subprogram_specification is separate + [aspect_specification]; + +24/2 + +25/2 + +26/2 + +27/2 + +28/2 + +29/2 + +30/2 + +31/2 + +1 + +2 + +3/3 + +10.1.2 Context Clauses - With Clauses + +13 December 2012 252 + + Ada Reference Manual — 2012 Edition + +package_body_stub ::= + package body defining_identifier is separate + [aspect_specification]; + +task_body_stub ::= + task body defining_identifier is separate + [aspect_specification]; + +protected_body_stub ::= + protected body defining_identifier is separate + [aspect_specification]; + +subunit ::= separate (parent_unit_name) proper_body + +Legality Rules + +The parent body of a subunit is the body of the program unit denoted by its parent_unit_name. The term +subunit is used to refer to a subunit and also to the proper_body of a subunit. The subunits of a program +unit include any subunit that names that program unit as its parent, as well as any subunit that names such +a subunit as its parent (recursively). + +4 + +5 + +6 + +7 + +8/2 + +The parent body of a subunit shall be present in the current environment, and shall contain a corresponding +body_stub with the same defining_identifier as the subunit. + +9 + +A package_body_stub shall be the completion of a package_declaration or generic_package_- +declaration; a task_body_stub shall be the completion of a task declaration; a protected_body_stub shall +be the completion of a protected declaration. + +10/3 + +In contrast, a subprogram_body_stub need not be the completion of a previous declaration, in which case +the _stub declares the subprogram. If the _stub is a completion, it shall be the completion of a +subprogram_declaration or generic_subprogram_declaration. The profile of a subprogram_body_stub +that completes a declaration shall conform fully to that of the declaration. + +A subunit that corresponds to a body_stub shall be of the same kind (package_, subprogram_, task_, or +protected_) as the body_stub. The profile of a subprogram_body subunit shall be fully conformant to that +of the corresponding body_stub. + +A body_stub shall appear immediately within the declarative_part of a compilation unit body. This rule +does not apply within an instance of a generic unit. + +The defining_identifiers of all body_stubs that appear immediately within a particular declarative_part +shall be distinct. + +For each body_stub, there shall be a subunit containing the corresponding proper_body. + +Post-Compilation Rules + +NOTES +4 The rules in 10.1.4, “The Compilation Process” say that a body_stub is equivalent to the corresponding proper_body. +This implies: + +• Visibility within a subunit is the visibility that would be obtained at the place of the corresponding body_stub + +(within the parent body) if the context_clause of the subunit were appended to that of the parent body. + +• The effect of the elaboration of a body_stub is to elaborate the subunit. + +11 + +12 + +13 + +14 + +15 + +16 + +17 + +18 + +253 13 December 2012 + +Subunits of Compilation Units 10.1.3 + + 19 + +20 + +21 + +22 + +23 + +24 + +1 + +2 + +3/2 + +4/3 + +Ada Reference Manual — 2012 Edition + +The package Parent is first written without subunits: + +Examples + +package Parent is + procedure Inner; +end Parent; +with Ada.Text_IO; +package body Parent is + Variable : String := "Hello, there."; + procedure Inner is + begin + Ada.Text_IO.Put_Line(Variable); + end Inner; +end Parent; + +The body of procedure Inner may be turned into a subunit by rewriting the package body as follows (with +the declaration of Parent remaining the same): + +package body Parent is + Variable : String := "Hello, there."; + procedure Inner is separate; +end Parent; +with Ada.Text_IO; +separate(Parent) +procedure Inner is +begin + Ada.Text_IO.Put_Line(Variable); +end Inner; + +10.1.4 The Compilation Process + +Each compilation unit submitted to the compiler is compiled in the context of an environment +declarative_part (or simply, an environment), which is a conceptual declarative_part that forms the +outermost declarative region of the context of any compilation. At run time, an environment forms the +declarative_part of the body of the environment task of a partition (see 10.2, “Program Execution”). + +The declarative_items of the environment are library_items appearing in an order such that there are no +forward semantic dependences. Each included subunit occurs in place of the corresponding stub. The +visibility rules apply as if the environment were the outermost declarative region, except that with_clauses +are needed to make declarations of library units visible (see 10.1.2). + +The mechanisms for creating an environment and for adding and replacing compilation units within an +environment are implementation defined. The mechanisms for adding a compilation unit mentioned in a +limited_with_clause to an environment are implementation defined. + +Name Resolution Rules + +If a library_unit_body that is a subprogram_body is submitted to the compiler, it is interpreted only as a +completion if a library_unit_declaration with the same defining_program_unit_name already exists in the +environment for a subprogram other than an instance of a generic subprogram or for a generic subprogram +(even if the profile of the body is not type conformant with that of the declaration); otherwise, the +subprogram_body is interpreted as both the declaration and body of a library subprogram. + +5 + +When a compilation unit is compiled, all compilation units upon which it depends semantically shall +already exist in the environment; the set of these compilation units shall be consistent in the sense that the + +Legality Rules + +10.1.3 Subunits of Compilation Units + +13 December 2012 254 + + Ada Reference Manual — 2012 Edition + +new compilation unit shall not semantically depend (directly or indirectly) on two different versions of the +same compilation unit, nor on an earlier version of itself. + +Implementation Permissions + +The implementation may require that a compilation unit be legal before it can be mentioned in a +limited_with_clause or it can be inserted into the environment. + +When a compilation unit that declares or renames a library unit is added to the environment, the +implementation may remove from the environment any preexisting library_item or subunit with the same +full expanded name. When a compilation unit that is a subunit or the body of a library unit is added to the +environment, the implementation may remove from the environment any preexisting version of the same +compilation unit. When a compilation unit that contains a body_stub is added to the environment, the +implementation may remove any preexisting library_item or subunit with the same full expanded name as +the body_stub. When a given compilation unit is removed from the environment, the implementation may +also remove any compilation unit that depends semantically upon the given one. If the given compilation +unit contains the body of a subprogram for which aspect Inline is True, the implementation may also +remove any compilation unit containing a call to that subprogram. + +NOTES +5 The rules of the language are enforced across compilation and compilation unit boundaries, just as they are enforced +within a single compilation unit. + +6 An implementation may support a concept of a library, which contains library_items. If multiple libraries are supported, +the implementation has to define how a single environment is constructed when a compilation unit is submitted to the +compiler. Naming conflicts between different libraries might be resolved by treating each library as the root of a hierarchy +of child library units. + +7 A compilation unit containing an instantiation of a separately compiled generic unit does not semantically depend on +the body of the generic unit. Therefore, replacing the generic body in the environment does not result in the removal of the +compilation unit containing the instantiation. + +10.1.5 Pragmas and Program Units + +This subclause discusses pragmas related to program units, library units, and compilations. + +Name Resolution Rules + +Certain pragmas are defined to be program unit pragmas. A name given as the argument of a program +unit pragma shall resolve to denote the declarations or renamings of one or more program units that occur +immediately within the declarative region or compilation in which the pragma immediately occurs, or it +shall resolve to denote the declaration of the immediately enclosing program unit (if any); the pragma +applies to the denoted program unit(s). If there are no names given as arguments, the pragma applies to +the immediately enclosing program unit. + +A program unit pragma shall appear in one of these places: + +Legality Rules + +• At the place of a compilation_unit, in which case the pragma shall immediately follow in the +same compilation (except for other pragmas) a library_unit_declaration that is a subprogram_- +declaration, generic_subprogram_declaration, or generic_instantiation, and the pragma shall +have an argument that is a name denoting that declaration. + +• Immediately within the visible part of a program unit and before any nested declaration (but not +within a generic formal part), in which case the argument, if any, shall be a direct_name that +denotes the immediately enclosing program unit declaration. + +6/2 + +7/3 + +8 + +9 + +10 + +1 + +2 + +3 + +4 + +5/1 + +255 13 December 2012 + +The Compilation Process 10.1.4 + + Ada Reference Manual — 2012 Edition + +6 + +• At the place of a declaration other than the first, of a declarative_part or program unit +declaration, in which case the pragma shall have an argument, which shall be a direct_name +that denotes one or more of the following (and nothing else): a subprogram_declaration, a +generic_subprogram_declaration, or a generic_instantiation, of the same declarative_part or +program unit declaration. + +7/3 + +Certain program unit pragmas are defined to be library unit pragmas. If a library unit pragma applies to a +program unit, the program unit shall be a library unit. + +7.1/1 + +A library unit pragma that applies to a generic unit does not apply to its instances, unless a specific rule for +the pragma specifies the contrary. + +Static Semantics + +8 + +9/2 + +Post-Compilation Rules + +Certain pragmas are defined to be configuration pragmas; they shall appear before the first +compilation_unit of a compilation. They are generally used to select a partition-wide or system-wide +option. The pragma applies to all compilation_units appearing in the compilation, unless there are none, in +which case it applies to all future compilation_units compiled into the same environment. + +Implementation Permissions + +An implementation may require that configuration pragmas that select partition-wide or system-wide +options be compiled when the environment contains no library_items other than those of the predefined +environment. In this case, the implementation shall still accept configuration pragmas in individual +compilations that confirm the initially selected partition-wide or system-wide options. + +10/1 + +When applied to a generic unit, a program unit pragma that is not a library unit pragma should apply to +each instance of the generic unit for which there is not an overriding pragma applied directly to the +instance. + +Implementation Advice + +1 + +2/2 + +3 + +10.1.6 Environment-Level Visibility Rules + +The normal visibility rules do not apply within a parent_unit_name or a context_clause, nor within a +pragma that appears at the place of a compilation unit. The special visibility rules for those contexts are +given here. + +Static Semantics + +the parent_unit_name at + +the beginning of an explicit + +Within +library_item, and within a +nonlimited_with_clause, the only declarations that are visible are those that are explicit library_items of +the environment, and the only declarations that are directly visible are those that are explicit root +library_items of the environment. Within a limited_with_clause, the only declarations that are visible are +those that are the implicit declaration of the limited view of a library package of the environment, and the +only declarations that are directly visible are those that are the implicit declaration of the limited view of a +root library package. + +Within a use_clause or pragma that is within a context_clause, each library_item mentioned in a +previous with_clause of the same context_clause is visible, and each root library_item so mentioned is +directly visible. In addition, within such a use_clause, if a given declaration is visible or directly visible, +each declaration that occurs immediately within the given declaration's visible part is also visible. No +other declarations are visible or directly visible. + +10.1.5 Pragmas and Program Units + +13 December 2012 256 + + Ada Reference Manual — 2012 Edition + +Within the parent_unit_name of a subunit, library_items are visible as they are in the parent_unit_name +of a library_item; in addition, the declaration corresponding to each body_stub in the environment is also +visible. + +Within a pragma that appears at the place of a compilation unit, the immediately preceding library_item +and each of its ancestors is visible. The ancestor root library_item is directly visible. + +Notwithstanding the rules of 4.1.3, an expanded name in a with_clause, a pragma in a context_clause, or +a pragma that appears at the place of a compilation unit may consist of a prefix that denotes a generic +package and a selector_name that denotes a child of that generic package. (The child is necessarily a +generic unit; see 10.1.1.) + +10.2 Program Execution + +An Ada program consists of a set of partitions, which can execute in parallel with one another, possibly in +a separate address space, and possibly on a separate computer. + +Post-Compilation Rules + +A partition is a program or part of a program that can be invoked from outside the Ada implementation. +For example, on many systems, a partition might be an executable file generated by the system linker. The +user can explicitly assign library units to a partition. The assignment is done in an implementation-defined +manner. The compilation units included in a partition are those of the explicitly assigned library units, as +well as other compilation units needed by those library units. The compilation units needed by a given +compilation unit are determined as follows (unless specified otherwise via an implementation-defined +pragma, or by some other implementation-defined means): + +• A compilation unit needs itself; +• If a compilation unit is needed, then so are any compilation units upon which it depends + +semantically; + +• If a library_unit_declaration is needed, then so is any corresponding library_unit_body; +• If a compilation unit with stubs is needed, then so are any corresponding subunits; +• If the (implicit) declaration of the limited view of a library package is needed, then so is the + +explicit declaration of the library package. + +The user can optionally designate (in an implementation-defined manner) one subprogram as the main +subprogram for the partition. A main subprogram, if specified, shall be a subprogram. + +Each partition has an anonymous environment task, which is an implicit outermost task whose execution +elaborates the library_items of the environment declarative_part, and then calls the main subprogram, if +there is one. A partition's execution is that of its tasks. + +The order of elaboration of library units is determined primarily by the elaboration dependences. There is +an elaboration dependence of a given library_item upon another if the given library_item or any of its +subunits depends semantically on the other library_item. In addition, if a given library_item or any of its +subunits has a pragma Elaborate or Elaborate_All that names another library unit, then there is an +elaboration dependence of the given library_item upon the body of the other library unit, and, for +Elaborate_All only, upon each library_item needed by the declaration of the other library unit. + +The environment task for a partition has the following structure: + +task Environment_Task; + +4 + +5 + +6/2 + +1 + +2 + +3 + +4 + +5 + +6/2 + +6.1/2 + +7 + +8 + +9 + +10 + +11 + +257 13 December 2012 + +Environment-Level Visibility Rules 10.1.6 + + 12 + +13 + +Ada Reference Manual — 2012 Edition + +task body Environment_Task is + ... (1) -- The environment declarative_part + -- (that is, the sequence of library_items) goes here. +begin + ... (2) -- Call the main subprogram, if there is one. +end Environment_Task; + +The environment declarative_part at (1) is a sequence of declarative_items consisting of copies of the +library_items included in the partition. The order of elaboration of library_items is the order in which they +appear in the environment declarative_part: + +14 + +• The order of all included library_items is such that there are no forward elaboration + +dependences. + +15/3 + +• Any included library_unit_declaration for which aspect Elaborate_Body is True (including when +a pragma Elaborate_Body applies) is immediately followed by its library_unit_body, if +included. + +16 + +17 + +18 + +19 + +20 + +21 + +22 + +23 + +24 + +25 + +26 + +• All library_items declared pure occur before any that are not declared pure. +• All preelaborated library_items occur before any that are not preelaborated. + +There shall be a total order of the library_items that obeys the above rules. The order is otherwise +implementation defined. + +The full expanded names of the library units and subunits included in a given partition shall be distinct. + +The sequence_of_statements of the environment task (see (2) above) consists of either: + +• A call to the main subprogram, if the partition has one. If the main subprogram has parameters, +they are passed; where the actuals come from is implementation defined. What happens to the +result of a main function is also implementation defined. + +or: + +• A null_statement, if there is no main subprogram. + +The mechanisms for building and running partitions are implementation defined. These might be +combined into one operation, as, for example, in dynamic linking, or “load-and-go” systems. + +Dynamic Semantics + +The execution of a program consists of the execution of a set of partitions. Further details are +implementation defined. The execution of a partition starts with the execution of its environment task, +ends when the environment task terminates, and includes the executions of all tasks of the partition. The +execution of the (implicit) task_body of the environment task acts as a master for all other tasks created as +part of the execution of the partition. When the environment task completes (normally or abnormally), it +waits for the termination of all such tasks, and then finalizes any remaining objects of the partition. + +Bounded (Run-Time) Errors + +Once the environment task has awaited the termination of all other tasks of the partition, any further +attempt to create a task (during finalization) is a bounded error, and may result in the raising of +Program_Error either upon creation or activation of the task. If such a task is activated, it is not specified +whether the task is awaited prior to termination of the environment task. + +27 + +The implementation shall ensure that all compilation units included in a partition are consistent with one +another, and are legal according to the rules of the language. + +Implementation Requirements + +10.2 Program Execution + +13 December 2012 258 + + The kind of partition described in this subclause is known as an active partition. An implementation is +allowed to support other kinds of partitions, with implementation-defined semantics. + +28/3 + +Implementation Permissions + +Ada Reference Manual — 2012 Edition + +An implementation may restrict the kinds of subprograms it supports as main subprograms. However, an +implementation is required to support all main subprograms that are public parameterless library +procedures. + +If the environment task completes abnormally, the implementation may abort any dependent tasks. + +NOTES +8 An implementation may provide inter-partition communication mechanism(s) via special packages and pragmas. +Standard pragmas for distribution and methods for specifying inter-partition communication are defined in Annex E, +“Distributed Systems”. If no such mechanisms are provided, then each partition is isolated from all others, and behaves as +a program in and of itself. + +9 Partitions are not required to run in separate address spaces. For example, an implementation might support dynamic +linking via the partition concept. + +10 An order of elaboration of library_items that is consistent with the partial ordering defined above does not always +ensure that each library_unit_body is elaborated before any other compilation unit whose elaboration necessitates that the +library_unit_body be already elaborated. (In particular, there is no requirement that the body of a library unit be elaborated +as soon as possible after the library_unit_declaration is elaborated, unless the pragmas in subclause 10.2.1 are used.) + +11 A partition (active or otherwise) need not have a main subprogram. In such a case, all the work done by the partition +would be done by elaboration of various library_items, and by tasks created by that elaboration. Passive partitions, which +cannot have main subprograms, are defined in Annex E, “Distributed Systems”. + +10.2.1 Elaboration Control + +This subclause defines pragmas that help control the elaboration order of library_items. + +Syntax +The form of a pragma Preelaborate is as follows: + pragma Preelaborate[(library_unit_name)]; + +A pragma Preelaborate is a library unit pragma. + +The form of a pragma Preelaborable_Initialization is as follows: + pragma Preelaborable_Initialization(direct_name); + +Legality Rules + +An elaborable construct is preelaborable unless its elaboration performs any of the following actions: + +• The execution of a statement other than a null_statement. +• A call to a subprogram other than a static function. +• The evaluation of a primary that is a name of an object, unless the name is a static expression, + +or statically denotes a discriminant of an enclosing type. + +• The creation of an object (including a component) that is initialized by default, if its type does +not have preelaborable initialization. Similarly, the evaluation of an extension_aggregate with +an ancestor subtype_mark denoting a subtype of such a type. + +29 + +30 + +31 + +32 + +33 + +34 + +1 + +2 + +3 + +4 + +4.1/2 + +4.2/2 + +5 + +6 + +7 + +8 + +9/3 + +A generic body is preelaborable only if elaboration of a corresponding instance body would not perform +any such actions, presuming that: + +10/2 + +• + +the actual for each discriminated formal derived type, formal private type, or formal private +extension declared within the formal part of the generic unit is a type that does not have + +10.1/3 + +259 13 December 2012 + +Program Execution 10.2 + + Ada Reference Manual — 2012 Edition + +10.2/2 + +10.3/2 + +10.4/2 + +11/3 + +preelaborable initialization, unless pragma Preelaborable_Initialization has been applied to the +formal type; + +• +• +• + +the actual for each formal type is nonstatic; + +the actual for each formal object is nonstatic; and + +the actual for each formal subprogram is a user-defined subprogram. + +A pragma Preelaborate (or pragma Pure — see below) is used to specify that a library unit is +preelaborated, namely that the Preelaborate aspect of the library unit is True; all compilation units of the +library unit are preelaborated. The declaration and body of a preelaborated library unit, and all subunits +that are elaborated as part of elaborating the library unit, shall be preelaborable. All compilation units of a +preelaborated library unit shall depend semantically only on declared pure or preelaborated library_items. +In addition to the places where Legality Rules normally apply (see 12.3), these rules also apply in the +private part of an instance of a generic unit. If a library unit is preelaborated, then its declaration, if any, +and body, if any, are elaborated prior to all nonpreelaborated library_items of the partition. + +11.1/2 + +The following rules specify which entities have preelaborable initialization: + +11.2/3 + +11.3/2 + +11.4/3 + +11.5/2 + +• The partial view of a private type or private extension, a protected type without +entry_declarations, a generic formal private type, or a generic formal derived type, has +preelaborable initialization if and only if the pragma Preelaborable_Initialization has been +applied to them. A protected type with entry_declarations or a task type never has preelaborable +initialization. + +• A component (including a discriminant) of a record or protected type has preelaborable +initialization if its declaration includes a default_expression whose execution does not perform +any actions prohibited in preelaborable constructs as described above, or if its declaration does +not include a default expression and its type has preelaborable initialization. + +• A derived type has preelaborable initialization if its parent type has preelaborable initialization +and if the noninherited components all have preelaborable initialization. However, a controlled +type with an Initialize procedure that is not a null procedure does not have preelaborable +initialization. + +• A view of a type has preelaborable initialization if it is an elementary type, an array type whose +component type has preelaborable initialization, a record type whose components all have +preelaborable initialization, or an interface type. + +11.6/2 + +A pragma Preelaborable_Initialization specifies that a type has preelaborable initialization. This pragma +shall appear in the visible part of a package or generic package. + +11.7/3 + +If the pragma appears in the first list of basic_declarative_items of a package_specification, then the +direct_name shall denote the first subtype of a composite type, and the type shall be declared immediately +within the same package as the pragma. If the pragma is applied to a private type or a private extension, +the full view of the type shall have preelaborable initialization. If the pragma is applied to a protected +type, the protected type shall not have entries, and each component of the protected type shall have +preelaborable initialization. For any other composite type, the type shall have preelaborable initialization. +In addition to the places where Legality Rules normally apply (see 12.3), these rules apply also in the +private part of an instance of a generic unit. + +11.8/2 + +If the pragma appears in a generic_formal_part, then the direct_name shall denote a generic formal +private type or a generic formal derived type declared in the same generic_formal_part as the pragma. In +a generic_instantiation the corresponding actual type shall have preelaborable initialization. + +10.2.1 Elaboration Control + +13 December 2012 260 + + Ada Reference Manual — 2012 Edition + +In an implementation, a type declared in a preelaborated package should have the same representation in +every elaboration of a given version of the package, whether the elaborations occur in distinct executions +of the same program, or in executions of distinct programs or partitions that include the given version. + +Implementation Advice + +The form of a pragma Pure is as follows: + pragma Pure[(library_unit_name)]; + +A pragma Pure is a library unit pragma. + +Syntax + +Static Semantics + +A pure compilation unit is a preelaborable compilation unit whose elaboration does not perform any of the +following actions: + +• +• + +• + +• + +the elaboration of a variable declaration; + +the evaluation of an allocator of an access-to-variable type; for the purposes of this rule, the +partial view of a type is presumed to have nonvisible components whose default initialization +evaluates such an allocator; + +the elaboration of the declaration of a nonderived named access-to-variable type unless the +Storage_Size of the type has been specified by a static expression with value zero or is defined +by the language to be zero; + +the elaboration of the declaration of a nonderived named access-to-constant type for which the +Storage_Size has been specified by an expression other than a static expression with value zero. + +A generic body is pure only if elaboration of a corresponding instance body would not perform any such +actions presuming any composite formal types have nonvisible components whose default initialization +evaluates an allocator of an access-to-variable type. + +12 + +13 + +14 + +15 + +15.1/3 + +15.2/2 + +15.3/2 + +15.4/3 + +15.5/3 + +15.6/3 + +The Storage_Size for an anonymous access-to-variable type declared at library level in a library unit that +is declared pure is defined to be zero. + +15.7/2 + +This paragraph was deleted. + +Legality Rules + +A pragma Pure is used to specify that a library unit is declared pure, namely that the Pure aspect of the +library unit is True; all compilation units of the library unit are declared pure. In addition, the limited view +of any library package is declared pure. The declaration and body of a declared pure library unit, and all +subunits that are elaborated as part of elaborating the library unit, shall be pure. All compilation units of a +declared pure library unit shall depend semantically only on declared pure library_items. In addition to the +places where Legality Rules normally apply (see 12.3), these rules also apply in the private part of an +instance of a generic unit. Furthermore, the full view of any partial view declared in the visible part of a +declared pure library unit that has any available stream attributes shall support external streaming (see +13.13.2). + +16/2 + +17/3 + +Implementation Permissions + +If a library unit is declared pure, then the implementation is permitted to omit a call on a library-level +subprogram of the library unit if the results are not needed after the call. In addition, the implementation +may omit a call on such a subprogram and simply reuse the results produced by an earlier call on the same +subprogram, provided that none of the parameters nor any object accessible via access values from the +parameters have any part that is of a type whose full type is an immutably limited type, and the addresses + +18/3 + +261 13 December 2012 + +Elaboration Control 10.2.1 + + Ada Reference Manual — 2012 Edition + +and values of all by-reference actual parameters, the values of all by-copy-in actual parameters, and the +values of all objects accessible via access values from the parameters, are the same as they were at the +earlier call. This permission applies even if the subprogram produces other side effects when called. + +Syntax + +19 + +20 + +21 + +22 + +23 + +24 + +The form of a pragma Elaborate, Elaborate_All, or Elaborate_Body is as follows: + pragma Elaborate(library_unit_name{, library_unit_name}); + + pragma Elaborate_All(library_unit_name{, library_unit_name}); + + pragma Elaborate_Body[(library_unit_name)]; + +A pragma Elaborate or Elaborate_All is only allowed within a context_clause. + +A pragma Elaborate_Body is a library unit pragma. + +25/3 + +If the aspect Elaborate_Body is True for a declaration (including when pragma Elaborate_Body applies), +then the declaration requires a completion (a body). + +25.1/2 + +The library_unit_name of a pragma Elaborate or Elaborate_All shall denote a nonlimited view of a +library unit. + +Legality Rules + +Static Semantics + +26/3 + +A pragma Elaborate specifies that the body of the named library unit is elaborated before the current +library_item. A pragma Elaborate_All specifies that each library_item that is needed by the named library +unit declaration is elaborated before the current library_item. + +26.1/3 + +A pragma Elaborate_Body sets the Elaborate_Body representation aspect of the library unit to which it +applies to the value True. If the Elaborate_Body aspect of a library unit is True, the body of the library +unit is elaborated immediately after its declaration. + +27 + +28 + +NOTES +12 A preelaborated library unit is allowed to have nonpreelaborable children. + +13 A library unit that is declared pure is allowed to have impure children. + +10.2.1 Elaboration Control + +13 December 2012 262 + + Ada Reference Manual — 2012 Edition + +11 Exceptions + +This clause defines the facilities for dealing with errors or other exceptional situations that arise during +program execution. An exception represents a kind of exceptional situation; an occurrence of such a +situation (at run time) is called an exception occurrence. To raise an exception is to abandon normal +program execution so as to draw attention to the fact that the corresponding situation has arisen. +Performing some actions in response to the arising of an exception is called handling the exception. + +An exception_declaration declares a name for an exception. An exception can be raised explicitly (for +example, by a raise_statement) or implicitly (for example, by the failure of a language-defined check). +When an exception arises, control can be transferred to a user-provided exception_handler at the end of a +handled_sequence_of_statements, or it can be propagated to a dynamically enclosing execution. + +11.1 Exception Declarations + +An exception_declaration declares a name for an exception. + +exception_declaration ::= defining_identifier_list : exception + [aspect_specification]; + +Syntax + +Static Semantics + +Each single exception_declaration declares a name for a different exception. If a generic unit includes an +exception_declaration, the exception_declarations implicitly generated by different instantiations of the +generic unit refer to distinct exceptions (but all have the same defining_identifier). The particular +exception denoted by an exception name is determined at compilation time and is the same regardless of +how many times the exception_declaration is elaborated. + +The predefined exceptions are the ones declared in the declaration of package Standard: Constraint_Error, +Program_Error, Storage_Error, and Tasking_Error; one of them is raised when a language-defined check +fails. + +The elaboration of an exception_declaration has no effect. + +Dynamic Semantics + +The execution of any construct raises Storage_Error if there is insufficient storage for that execution. The +amount of storage needed for the execution of constructs is unspecified. + +Examples of user-defined exception declarations: + +Singular : exception; +Error : exception; +Overflow, Underflow : exception; + +Examples + +1/3 + +2/3 + +1 + +2/3 + +3 + +4 + +5 + +6 + +7 + +8 + +263 13 December 2012 + +Exceptions 11 + + 1 + +2 + +3 + +4 + +5 + +6 + +7 + +8 + +9 + +10 + +11 + +12 + +Ada Reference Manual — 2012 Edition + +11.2 Exception Handlers + +The response to one or more exceptions is specified by an exception_handler. + +Syntax + +handled_sequence_of_statements ::= + sequence_of_statements + [exception + exception_handler + {exception_handler}] + +exception_handler ::= + when [choice_parameter_specification:] exception_choice {| exception_choice} => + sequence_of_statements + +choice_parameter_specification ::= defining_identifier + +exception_choice ::= exception_name | others + +Legality Rules + +A choice with an exception_name covers the named exception. A choice with others covers all exceptions +not named by previous choices of the same handled_sequence_of_statements. Two choices in different +exception_handlers of the same handled_sequence_of_statements shall not cover the same exception. + +A choice with others is allowed only for the last handler of a handled_sequence_of_statements and as +the only choice of that handler. + +An exception_name of a choice shall not denote an exception declared in a generic formal package. + +A choice_parameter_specification declares a choice parameter, which is a constant object of type +Exception_Occurrence (see 11.4.1). During the handling of an exception occurrence, the choice parameter, +if any, of the handler represents the exception occurrence that is being handled. + +Static Semantics + +The execution of a handled_sequence_of_statements consists of the execution of the sequence_of_- +statements. The optional handlers are used to handle any exceptions that are propagated by the +sequence_of_statements. + +Dynamic Semantics + +Example of an exception handler: + +Examples + +begin + Open(File, In_File, "input.txt"); -- see A.8.2 +exception + when E : Name_Error => + Put("Cannot open input file : "); + Put_Line(Exception_Message(E)); -- see 11.4.1 + raise; +end; + +11.2 Exception Handlers + +13 December 2012 264 + + Ada Reference Manual — 2012 Edition + +11.3 Raise Statements + +A raise_statement raises an exception. + +raise_statement ::= raise; + | raise exception_name [with string_expression]; + +Syntax + +Legality Rules + +The name, if any, in a raise_statement shall denote an exception. A raise_statement with no +exception_name (that is, a re-raise statement) shall be within a handler, but not within a body enclosed by +that handler. + +The expression, if any, in a raise_statement, is expected to be of type String. + +Name Resolution Rules + +Dynamic Semantics + +To raise an exception is to raise a new occurrence of that exception, as explained in 11.4. For the +execution of a raise_statement with an exception_name, the named exception is raised. If a +string_expression is present, the expression is evaluated and its value is associated with the exception +occurrence. For the execution of a re-raise statement, the exception occurrence that caused transfer of +control to the innermost enclosing handler is raised again. + +Examples of raise statements: + +Examples + +raise Ada.IO_Exceptions.Name_Error; -- see A.13 +raise Queue_Error with "Buffer Full"; -- see 9.11 +raise; -- re-raise the current exception + +11.4 Exception Handling + +When an exception occurrence is raised, normal program execution is abandoned and control is transferred +to an applicable exception_handler, if any. To handle an exception occurrence is to respond to the +exceptional event. To propagate an exception occurrence is to raise it again in another context; that is, to +fail to respond to the exceptional event in the present context. + +Dynamic Semantics + +Within a given task, if the execution of construct a is defined by this International Standard to consist (in +part) of the execution of construct b, then while b is executing, the execution of a is said to dynamically +enclose the execution of b. The innermost dynamically enclosing execution of a given execution is the +dynamically enclosing execution that started most recently. + +When an exception occurrence is raised by the execution of a given construct, the rest of the execution of +that construct is abandoned; that is, any portions of the execution that have not yet taken place are not +performed. The construct is first completed, and then left, as explained in 7.6.1. Then: + +• If the construct is a task_body, the exception does not propagate further; +• If the construct is the sequence_of_statements of a handled_sequence_of_statements that +has a handler with a choice covering the exception, the occurrence is handled by that handler; + +265 13 December 2012 + +Raise Statements 11.3 + +1 + +2/2 + +3 + +3.1/2 + +4/2 + +5 + +6/2 + +7 + +1 + +2 + +3 + +4 + +5 + + Ada Reference Manual — 2012 Edition + +• Otherwise, the occurrence is propagated to the innermost dynamically enclosing execution, + +which means that the occurrence is raised again in that context. + +When an occurrence is handled by a given handler, the choice_parameter_specification, if any, is first +elaborated, which creates the choice parameter and initializes it to the occurrence. Then, the +sequence_of_statements of the handler is executed; this execution replaces the abandoned portion of the +execution of the sequence_of_statements. + +NOTES +1 Note that exceptions raised in a declarative_part of a body are not handled by the handlers of the handled_- +sequence_of_statements of that body. + +11.4.1 The Package Exceptions + +The following language-defined library package exists: + +Static Semantics + +with Ada.Streams; +package Ada.Exceptions is + pragma Preelaborate(Exceptions); + type Exception_Id is private; + pragma Preelaborable_Initialization(Exception_Id); + Null_Id : constant Exception_Id; + function Exception_Name(Id : Exception_Id) return String; + function Wide_Exception_Name(Id : Exception_Id) return Wide_String; + function Wide_Wide_Exception_Name(Id : Exception_Id) + return Wide_Wide_String; + type Exception_Occurrence is limited private; + pragma Preelaborable_Initialization(Exception_Occurrence); + type Exception_Occurrence_Access is access all Exception_Occurrence; + Null_Occurrence : constant Exception_Occurrence; + procedure Raise_Exception(E : in Exception_Id; + Message : in String := "") + with No_Return; + function Exception_Message(X : Exception_Occurrence) return String; + procedure Reraise_Occurrence(X : in Exception_Occurrence); + function Exception_Identity(X : Exception_Occurrence) + return Exception_Id; + function Exception_Name(X : Exception_Occurrence) return String; + -- Same as Exception_Name(Exception_Identity(X)). + function Wide_Exception_Name(X : Exception_Occurrence) + return Wide_String; + -- Same as Wide_Exception_Name(Exception_Identity(X)). + function Wide_Wide_Exception_Name(X : Exception_Occurrence) + return Wide_Wide_String; + -- Same as Wide_Wide_Exception_Name(Exception_Identity(X)). + function Exception_Information(X : Exception_Occurrence) return String; + procedure Save_Occurrence(Target : out Exception_Occurrence; + Source : in Exception_Occurrence); + function Save_Occurrence(Source : Exception_Occurrence) + return Exception_Occurrence_Access; + procedure Read_Exception_Occurrence + (Stream : not null access Ada.Streams.Root_Stream_Type'Class; + Item : out Exception_Occurrence); + procedure Write_Exception_Occurrence + (Stream : not null access Ada.Streams.Root_Stream_Type'Class; + Item : in Exception_Occurrence); + for Exception_Occurrence'Read use Read_Exception_Occurrence; + for Exception_Occurrence'Write use Write_Exception_Occurrence; + +6 + +7 + +8 + +1 + +2/2 + +3/2 + +4/3 + +5/2 + +6/2 + +6.1/2 + +6.2/2 + +11.4 Exception Handling + +13 December 2012 266 + + Ada Reference Manual — 2012 Edition + +private + ... -- not specified by the language +end Ada.Exceptions; + +Each distinct exception is represented by a distinct value of type Exception_Id. Null_Id does not represent +any exception, and is the default initial value of type Exception_Id. Each occurrence of an exception is +represented by a value of type Exception_Occurrence. Null_Occurrence does not represent any exception +occurrence, and is the default initial value of type Exception_Occurrence. + +For a prefix E that denotes an exception, the following attribute is defined: + +E'Identity + +E'Identity returns the unique identity of the exception. The type of this attribute is +Exception_Id. + +Raise_Exception raises a new occurrence of the identified exception. + +Exception_Message returns the message associated with the given Exception_Occurrence. For an +occurrence raised by a call to Raise_Exception, the message is the Message parameter passed to +Raise_Exception. For the occurrence raised by a raise_statement with an exception_name and a +string_expression, the message is the string_expression. For the occurrence raised by a raise_statement +with an exception_name but without a string_expression, the message is a string giving implementation- +defined information about the exception occurrence. For an occurrence originally raised in some other +manner (including by the failure of a language-defined check), the message is an unspecified string. In all +cases, Exception_Message returns a string with lower bound 1. + +Reraise_Occurrence reraises the specified exception occurrence. + +Exception_Identity returns the identity of the exception of the occurrence. + +The Wide_Wide_Exception_Name functions return the full expanded name of the exception, in upper +case, starting with a root library unit. For an exception declared immediately within package Standard, the +defining_identifier is returned. The result is implementation defined if the exception is declared within an +unnamed block_statement. + +The Exception_Name functions (respectively, Wide_Exception_Name) return the same sequence of +graphic characters as that defined for Wide_Wide_Exception_Name, if all the graphic characters are +defined +is +implementation defined, but no shorter than that returned by Wide_Wide_Exception_Name for the same +value of the argument. + +in Character (respectively, Wide_Character); otherwise, + +the sequence of characters + +6.3/2 + +7 + +8/1 + +9 + +10/2 + +10.1/3 + +10.2/2 + +11 + +12/2 + +12.1/2 + +The string returned by the Exception_Name, Wide_Exception_Name, and Wide_Wide_Exception_Name +functions has lower bound 1. + +12.2/2 + +Exception_Information returns implementation-defined information about the exception occurrence. The +returned string has lower bound 1. + +Reraise_Occurrence has no effect in the case of Null_Occurrence. Raise_Exception and Exception_Name +raise Constraint_Error for a Null_Id. Exception_Message, Exception_Name, and Exception_Information +raise Constraint_Error for a Null_Occurrence. Exception_Identity applied to Null_Occurrence returns +Null_Id. + +The Save_Occurrence procedure copies the Source to the Target. The Save_Occurrence function uses an +allocator of type Exception_Occurrence_Access to create a new object, copies the Source to this new +object, and returns an access value designating this new object; the result may be deallocated using an +instance of Unchecked_Deallocation. + +13/2 + +14/2 + +15 + +267 13 December 2012 + +The Package Exceptions 11.4.1 + + Ada Reference Manual — 2012 Edition + +15.1/2 + +Write_Exception_Occurrence writes a representation of an exception occurrence +to a stream; +Read_Exception_Occurrence reconstructs an exception occurrence from a stream (including one written in +a different partition). + +Paragraph 16 was deleted. + +17 + +18 + +19 + +1/3 + +1.1/3 + +Implementation Permissions + +An implementation of Exception_Name in a space-constrained environment may return the defining_- +identifier instead of the full expanded name. + +The string returned by Exception_Message may be truncated (to no less than 200 characters) by the +Save_Occurrence procedure (not the function), the Reraise_Occurrence procedure, and the re-raise +statement. + +Implementation Advice + +Exception_Message (by default) and Exception_Information should produce information useful for +debugging. Exception_Message should be short (about one line), whereas Exception_Information can be +long. Exception_Message should not include the Exception_Name. Exception_Information should include +both the Exception_Name and the Exception_Message. + +11.4.2 Pragmas Assert and Assertion_Policy + +Pragma Assert is used to assert the truth of a boolean expression at a point within a sequence of +declarations or statements. + +Assert pragmas, subtype predicates (see 3.2.4), preconditions and postconditions (see 6.1.1), and type +invariants (see 7.3.2) are collectively referred to as assertions; their boolean expressions are referred to as +assertion expressions. + +1.2/3 + +Pragma Assertion_Policy is used to control whether assertions are to be ignored by the implementation, +checked at run time, or handled in some implementation-defined manner. + +2/2 + +3/2 + +4/2 + +5/2 + +6/2 + +6.1/3 + +7/3 + +8/2 + +The form of a pragma Assert is as follows: + pragma Assert([Check =>] boolean_expression[, [Message =>] string_expression]); + +A pragma Assert is allowed at the place where a declarative_item or a statement is allowed. + +Syntax + +The form of a pragma Assertion_Policy is as follows: + pragma Assertion_Policy(policy_identifier); + + pragma Assertion_Policy( + assertion_aspect_mark => policy_identifier + {, assertion_aspect_mark => policy_identifier}); + +A pragma Assertion_Policy is allowed only immediately within a declarative_part, immediately +within a package_specification, or as a configuration pragma. + +The expected type for the boolean_expression of a pragma Assert is any boolean type. The expected type +for the string_expression of a pragma Assert is type String. + +Name Resolution Rules + +11.4.1 The Package Exceptions + +13 December 2012 268 + + Ada Reference Manual — 2012 Edition + +Legality Rules + +The assertion_aspect_mark of a pragma Assertion_Policy shall be one of Assert, Static_Predicate, +Dynamic_Predicate, Pre, Pre'Class, Post, Post'Class, Type_Invariant, Type_Invariant'Class, or some +implementation defined aspect_mark. The policy_identifier shall be either Check, Ignore, or some +implementation-defined identifier. + +9/3 + +Static Semantics + +each + +assertion + +determines + +pragma Assertion_Policy + +the +for +A +pragma_argument_associations whether assertions of the given aspect are to be enforced by a run-time +check. The policy_identifier Check requires that assertion expressions of the given aspect be checked that +they evaluate to True at the points specified for the given aspect; the policy_identifier Ignore requires that +the assertion expression not be evaluated at these points, and the run-time checks not be performed. Note +that for subtype predicate aspects (see 3.2.4), even when the applicable Assertion_Policy is Ignore, the +predicate will still be evaluated as part of membership tests and Valid attribute_references, and if static, +will +selection of +iteration over +loop +still have an effect on +case_statement_alternatives and variants. + +subtype, and + +named + +aspect + +the + +the + +in + +10/3 + +If no assertion_aspect_marks are specified in the pragma, the specified policy applies to all assertion +aspects. + +10.1/3 + +A pragma Assertion_Policy applies to the named assertion aspects in a specific region, and applies to all +assertion expressions specified in that region. A pragma Assertion_Policy given in a declarative_part or +immediately within a package_specification applies from the place of the pragma to the end of the +innermost enclosing declarative region. The region for a pragma Assertion_Policy given as a +configuration pragma is the declarative region for the entire compilation unit (or units) to which it applies. + +10.2/3 + +If a pragma Assertion_Policy applies to a generic_instantiation, then the pragma Assertion_Policy +applies to the entire instance. + +10.3/3 + +If multiple Assertion_Policy pragmas apply to a given construct for a given assertion aspect, the assertion +policy is determined by the one in the innermost enclosing region of a pragma Assertion_Policy +specifying a policy for the assertion aspect. If no such Assertion_Policy pragma exists, the policy is +implementation defined. + +10.4/3 + +The following language-defined library package exists: + +package Ada.Assertions is + pragma Pure(Assertions); + Assertion_Error : exception; + procedure Assert(Check : in Boolean); + procedure Assert(Check : in Boolean; Message : in String); +end Ada.Assertions; + +A compilation unit containing a check for an assertion (including a pragma Assert) has a semantic +dependence on the Assertions library unit. + +This paragraph was deleted. + +Dynamic Semantics + +If performing checks is required by the Assert assertion policy in effect at the place of a pragma Assert, +the elaboration of the pragma consists of evaluating the boolean expression, and if the result is False, +evaluating the Message argument, if any, and raising the exception Assertions.Assertion_Error, with a +message if the Message argument is provided. + +11/2 + +12/2 + +13/2 + +14/2 + +15/2 + +16/3 + +17/3 + +18/3 + +269 13 December 2012 + +Pragmas Assert and Assertion_Policy 11.4.2 + + Ada Reference Manual — 2012 Edition + +19/2 + +20/2 + +21/2 + +22/2 + +Calling the procedure Assertions.Assert without a Message parameter is equivalent to: + +if Check = False then + raise Ada.Assertions.Assertion_Error; +end if; + +Calling the procedure Assertions.Assert with a Message parameter is equivalent to: + +if Check = False then + raise Ada.Assertions.Assertion_Error with Message; +end if; + +23/2 + +The procedures Assertions.Assert have these effects independently of the assertion policy in effect. + +23.1/3 + +It is a bounded error to invoke a potentially blocking operation (see 9.5.1) during the evaluation of an +assertion expression associated with a call on, or return from, a protected operation. If the bounded error is +detected, Program_Error is raised. If not detected, execution proceeds normally, but if it is invoked within +a protected action, it might result in deadlock or a (nested) protected action. + +Bounded (Run-Time) Errors + +24/2 + +Assertion_Error may be declared by renaming an implementation-defined exception from another +package. + +Implementation Permissions + +25/2 + +Implementations may define their own assertion policies. + +26/3 + +27/3 + +28/2 + +If the result of a function call in an assertion is not needed to determine the value of the assertion +expression, an implementation is permitted to omit the function call. This permission applies even if the +function has side effects. + +An implementation need not allow the specification of an assertion expression if the evaluation of the +expression has a side effect such that an immediate reevaluation of the expression could produce a +different value. Similarly, an implementation need not allow the specification of an assertion expression +that is checked as part of a call on or return from a callable entity C, if the evaluation of the expression has +a side effect such that the evaluation of some other assertion expression associated with the same call of +(or return from) C could produce a different value than it would if the first expression had not been +evaluated. + +NOTES +2 Normally, the boolean expression in a pragma Assert should not call functions that have significant side effects when +the result of the expression is True, so that the particular assertion policy in effect will not affect normal operation of the +program. + +11.4.2 Pragmas Assert and Assertion_Policy + +13 December 2012 270 + + Ada Reference Manual — 2012 Edition + +11.4.3 Example of Exception Handling + +Examples + +Exception handling may be used to separate the detection of an error from the response to that error: + +package File_System is + type File_Handle is limited private; + File_Not_Found : exception; + procedure Open(F : in out File_Handle; Name : String); + -- raises File_Not_Found if named file does not exist + End_Of_File : exception; + procedure Read(F : in out File_Handle; Data : out Data_Type); + -- raises End_Of_File if the file is not open + ... +end File_System; +package body File_System is + procedure Open(F : in out File_Handle; Name : String) is + begin + if File_Exists(Name) then + ... + else + raise File_Not_Found with "File not found: " & Name & "."; + end if; + end Open; + procedure Read(F : in out File_Handle; Data : out Data_Type) is + begin + if F.Current_Position <= F.Last_Position then + ... + else + raise End_Of_File; + end if; + end Read; + ... +end File_System; +with Ada.Text_IO; +with Ada.Exceptions; +with File_System; use File_System; +use Ada; +procedure Main is +begin + ... -- call operations in File_System +exception + when End_Of_File => + Close(Some_File); + when Not_Found_Error : File_Not_Found => + Text_IO.Put_Line(Exceptions.Exception_Message(Not_Found_Error)); + when The_Error : others => + Text_IO.Put_Line("Unknown error:"); + if Verbosity_Desired then + Text_IO.Put_Line(Exceptions.Exception_Information(The_Error)); + else + Text_IO.Put_Line(Exceptions.Exception_Name(The_Error)); + Text_IO.Put_Line(Exceptions.Exception_Message(The_Error)); + end if; + raise; +end Main; + +1 + +2/2 + +3 + +4 + +5 + +6/2 + +7 + +8 + +9 + +10 + +In the above example, the File_System package contains information about detecting certain exceptional +situations, but it does not specify how to handle those situations. Procedure Main specifies how to handle + +11 + +271 13 December 2012 + +Example of Exception Handling 11.4.3 + + Ada Reference Manual — 2012 Edition + +them; other clients of File_System might have different handlers, even though the exceptional situations +arise from the same basic causes. + +11.5 Suppressing Checks + +Checking pragmas give instructions to an implementation on handling language-defined checks. A +pragma Suppress gives permission to an implementation to omit certain language-defined checks, while a +pragma Unsuppress revokes the permission to omit checks.. + +A language-defined check (or simply, a “check”) is one of the situations defined by this International +Standard that requires a check to be made at run time to determine whether some condition is true. A +check fails when the condition being checked is False, causing an exception to be raised. + +The forms of checking pragmas are as follows: + pragma Suppress(identifier); + + pragma Unsuppress(identifier); + +Syntax + +A checking pragma is allowed only immediately within a declarative_part, immediately within a +package_specification, or as a configuration pragma. + +The identifier shall be the name of a check. + +This paragraph was deleted. + +Legality Rules + +Static Semantics + +A checking pragma applies to the named check in a specific region, and applies to all entities in that +region. A checking pragma given in a declarative_part or immediately within a package_specification +applies from the place of the pragma to the end of the innermost enclosing declarative region. The region +for a checking pragma given as a configuration pragma is the declarative region for the entire compilation +unit (or units) to which it applies. + +If a checking pragma applies to a generic_instantiation, then the checking pragma also applies to the +entire instance. + +A pragma Suppress gives permission to an implementation to omit the named check (or every check in the +case of All_Checks) for any entities to which it applies. If permission has been given to suppress a given +check, the check is said to be suppressed. + +A pragma Unsuppress revokes the permission to omit the named check (or every check in the case of +All_Checks) given by any pragma Suppress that applies at the point of the pragma Unsuppress. The +permission is revoked for the region to which the pragma Unsuppress applies. If there is no such +permission at the point of a pragma Unsuppress, then the pragma has no effect. A later pragma Suppress +can renew the permission. + +The following are the language-defined checks: + +• The following checks correspond to situations in which the exception Constraint_Error is raised + +upon failure. + +1/2 + +2/3 + +3/2 + +4/2 + +4.1/2 + +5/2 + +6/2 + +7/2 + +7.1/2 + +7.2/3 + +8/2 + +8.1/2 + +9 + +10 + +11.4.3 Example of Exception Handling + +13 December 2012 272 + + Ada Reference Manual — 2012 Edition + +Access_Check + +When evaluating a dereference (explicit or implicit), check that the value of the name +is not null. When converting to a subtype that excludes null, check that the converted +value is not null. + +Discriminant_Check + +Check that the discriminants of a composite value have the values imposed by a +discriminant constraint. Also, when accessing a record component, check that it exists +for the current discriminant values. + +Division_Check + +Check that the second operand is not zero for the operations /, rem and mod. + +Index_Check + +Check that the bounds of an array value are equal to the corresponding bounds of an +index constraint. Also, when accessing a component of an array object, check for each +dimension that the given index value belongs to the range defined by the bounds of the +array object. Also, when accessing a slice of an array object, check that the given +discrete range is compatible with the range defined by the bounds of the array object. + +Length_Check + +Check that two arrays have matching components, in the case of array subtype +conversions, and logical operators for arrays of boolean components. + +Overflow_Check + +Check that a scalar value is within the base range of its type, in cases where the +implementation chooses to raise an exception instead of returning the correct +mathematical result. + +Range_Check + +Check that a scalar value satisfies a range constraint. Also, for the elaboration of a +subtype_indication, check that the constraint (if present) is compatible with the +subtype denoted by the subtype_mark. Also, for an aggregate, check that an index or +discriminant value belongs to the corresponding subtype. Also, check that when the +result of an operation yields an array, the value of each component belongs to the +component subtype. + +Tag_Check + +Check that operand tags in a dispatching call are all equal. Check for the correct tag on +tagged type conversions, for an assignment_statement, and when returning a tagged +limited object from a function. + +• The following checks correspond to situations in which the exception Program_Error is raised + +upon failure. + +Accessibility_Check + +Check the accessibility level of an entity or view. + +Allocation_Check + +For an allocator, check that the master of any tasks to be created by the allocator is not +yet completed or some dependents have not yet terminated, and that the finalization of +the collection has not started. + +Elaboration_Check + +When a subprogram or protected entry is called, a task activation is accomplished, or a +generic instantiation is elaborated, check that the body of the corresponding unit has +already been elaborated. + +This paragraph was deleted. + +11/2 + +12 + +13/2 + +14 + +15 + +16 + +17 + +18 + +19 + +19.1/2 + +19.2/2 + +20 + +21/2 + +273 13 December 2012 + +Suppressing Checks 11.5 + + + + + + + + + + + + + + Ada Reference Manual — 2012 Edition + +22 + +23 + +24 + +25/3 + +• The following check corresponds to situations in which the exception Storage_Error is raised + +upon failure. + +Storage_Check + +Check that evaluation of an allocator does not require more space than is available for +a storage pool. Check that the space available for a task or subprogram has not been +exceeded. + +• The following check corresponds to all situations in which any predefined exception is raised. + +All_Checks + +Represents the union of all checks; suppressing All_Checks suppresses all checks +other than those associated with assertions. In addition, an implementation is allowed +(but not required) to behave as if a pragma Assertion_Policy(Ignore) applies to any +region to which pragma Suppress(All_Checks) applies. + +26 + +If a given check has been suppressed, and the corresponding error situation occurs, the execution of the +program is erroneous. + +Erroneous Execution + +Implementation Permissions + +27/2 + +An implementation is allowed to place restrictions on checking pragmas, subject only to the requirement +that pragma Unsuppress shall allow any check names supported by pragma Suppress. An implementation +is allowed to add additional check names, with implementation-defined semantics. When Overflow_Check +has been suppressed, an implementation may also suppress an unspecified subset of the Range_Checks. + +27.1/2 + +An implementation may support an additional parameter on pragma Unsuppress similar to the one +allowed for pragma Suppress (see J.10). The meaning of such a parameter is implementation-defined. + +28 + +The implementation should minimize the code executed for checks that have been suppressed. + +Implementation Advice + +29 + +29.1/2 + +30/2 + +31/2 + +NOTES +3 There is no guarantee that a suppressed check is actually removed; hence a pragma Suppress should be used only for +efficiency reasons. + +4 It is possible to give both a pragma Suppress and Unsuppress for the same check immediately within the same +declarative_part. In that case, the last pragma given determines whether or not the check is suppressed. Similarly, it is +possible to resuppress a check which has been unsuppressed by giving a pragma Suppress in an inner declarative region. + +Examples of suppressing and unsuppressing checks: + +pragma Suppress(Index_Check); +pragma Unsuppress(Overflow_Check); + +Examples + +11.5 Suppressing Checks + +13 December 2012 274 + + + + Ada Reference Manual — 2012 Edition + +11.6 Exceptions and Optimization + +This subclause gives permission to the implementation to perform certain “optimizations” that do not +necessarily preserve the canonical semantics. + +1/3 + +Dynamic Semantics + +The rest of this International Standard (outside this subclause) defines the canonical semantics of the +language. The canonical semantics of a given (legal) program determines a set of possible external effects +that can result from the execution of the program with given inputs. + +As explained in 1.1.3, “Conformity of an Implementation with the Standard”, the external effect of a +program is defined in terms of its interactions with its external environment. Hence, the implementation +can perform any internal actions whatsoever, in any order or in parallel, so long as the external effect of +the execution of the program is one that is allowed by the canonical semantics, or by the rules of this +subclause. + +The following additional permissions are granted to the implementation: + +Implementation Permissions + +• An implementation need not always raise an exception when a language-defined check fails. +Instead, the operation that failed the check can simply yield an undefined result. The exception +need be raised by the implementation only if, in the absence of raising it, the value of this +undefined result would have some effect on the external interactions of the program. In +determining this, the implementation shall not presume that an undefined result has a value that +belongs to its subtype, nor even to the base range of its type, if scalar. Having removed the raise +of the exception, the canonical semantics will in general allow the implementation to omit the +code for the check, and some or all of the operation itself. + +• If an exception is raised due to the failure of a language-defined check, then upon reaching the +corresponding exception_handler (or the termination of the task, if none), the external +interactions that have occurred need reflect only that the exception was raised somewhere within +the execution of the sequence_of_statements with the handler (or the task_body), possibly +earlier (or later if the interactions are independent of the result of the checked operation) than +that defined by the canonical semantics, but not within the execution of some abort-deferred +operation or independent subprogram that does not dynamically enclose the execution of the +construct whose check failed. An independent subprogram is one that is defined outside the +library unit containing the construct whose check failed, and for which the Inline aspect is False. +Any assignment that occurred outside of such abort-deferred operations or independent +subprograms can be disrupted by the raising of the exception, causing the object or its parts to +become abnormal, and certain subsequent uses of the object to be erroneous, as explained in +13.9.1. + +2/3 + +3/3 + +4 + +5 + +6/3 + +NOTES +5 The permissions granted by this subclause can have an effect on the semantics of a program only if the program fails a +language-defined check. + +7/3 + +275 13 December 2012 + +Exceptions and Optimization 11.6 + + Ada Reference Manual — 2012 Edition + +12 Generic Units + +A generic unit is a program unit that is either a generic subprogram or a generic package. A generic unit is +a template, which can be parameterized, and from which corresponding (nongeneric) subprograms or +packages can be obtained. The resulting program units are said to be instances of the original generic unit. + +A generic unit is declared by a generic_declaration. This form of declaration has a generic_formal_part +declaring any generic formal parameters. An instance of a generic unit is obtained as the result of a +generic_instantiation with appropriate generic actual parameters for the generic formal parameters. An +instance of a generic subprogram is a subprogram. An instance of a generic package is a package. + +Generic units are templates. As templates they do not have the properties that are specific to their +nongeneric counterparts. For example, a generic subprogram can be instantiated but it cannot be called. In +contrast, an instance of a generic subprogram is a (nongeneric) subprogram; hence, this instance can be +called but it cannot be used to produce further instances. + +12.1 Generic Declarations + +A generic_declaration declares a generic unit, which is either a generic subprogram or a generic package. +A generic_declaration includes a generic_formal_part declaring any generic formal parameters. A +generic formal parameter can be an object; alternatively (unlike a parameter of a subprogram), it can be a +type, a subprogram, or a package. + +generic_declaration ::= generic_subprogram_declaration | generic_package_declaration + +Syntax + +generic_subprogram_declaration ::= + generic_formal_part subprogram_specification + [aspect_specification]; + +generic_package_declaration ::= + generic_formal_part package_specification; + +generic_formal_part ::= generic {generic_formal_parameter_declaration | use_clause} + +generic_formal_parameter_declaration ::= + formal_object_declaration + | formal_type_declaration + | formal_subprogram_declaration + | formal_package_declaration + +The only form of subtype_indication allowed within a generic_formal_part is a subtype_mark (that +is, the subtype_indication shall not include an explicit constraint). The defining name of a generic +subprogram shall be an identifier (not an operator_symbol). + +Static Semantics + +A generic_declaration declares a generic unit — a generic package, generic procedure, or generic +function, as appropriate. + +An entity is a generic formal entity if it is declared by a generic_formal_parameter_declaration. “Generic +formal,” or simply “formal,” is used as a prefix in referring to objects, subtypes (and types), functions, +procedures and packages, that are generic formal entities, as well as to their respective declarations. +Examples: “generic formal procedure” or a “formal integer type declaration.” + +277 13 December 2012 + +Generic Units 12 + +1 + +2 + +3 + +1 + +2 + +3/3 + +4 + +5 + +6 + +7 + +8/2 + +9 + + Ada Reference Manual — 2012 Edition + +10 + +The elaboration of a generic_declaration has no effect. + +Dynamic Semantics + +11 + +12 + +13 + +14 + +15 + +16 + +17 + +18 + +19 + +20 + +21 + +22 + +23 + +24 + +NOTES +1 Outside a generic unit a name that denotes the generic_declaration denotes the generic unit. In contrast, within the +declarative region of the generic unit, a name that denotes the generic_declaration denotes the current instance. + +2 Within a generic subprogram_body, the name of this program unit acts as the name of a subprogram. Hence this name +can be overloaded, and it can appear in a recursive call of the current instance. For the same reason, this name cannot +appear after the reserved word new in a (recursive) generic_instantiation. + +3 A default_expression or default_name appearing in a generic_formal_part is not evaluated during elaboration of the +generic_formal_part; instead, it is evaluated when used. (The usual visibility rules apply to any name used in a default: +the denoted declaration therefore has to be visible at the place of the expression.) + +Examples of generic formal parts: + +Examples + +generic -- parameterless +generic + Size : Natural; -- formal object +generic + Length : Integer := 200; -- formal object with a default expression + Area : Integer := Length*Length; -- formal object with a default expression +generic + type Item is private; -- formal type + type Index is (<>); -- formal type + type Row is array(Index range <>) of Item; -- formal type + with function "<"(X, Y : Item) return Boolean; -- formal subprogram + +Examples of generic declarations declaring generic subprograms Exchange and Squaring: + +generic + type Elem is private; +procedure Exchange(U, V : in out Elem); +generic + type Item is private; + with function "*"(U, V : Item) return Item is <>; +function Squaring(X : Item) return Item; + +Example of a generic declaration declaring a generic package: + +generic + type Item is private; + type Vector is array (Positive range <>) of Item; + with function Sum(X, Y : Item) return Item; +package On_Vectors is + function Sum (A, B : Vector) return Vector; + function Sigma(A : Vector) return Item; + Length_Error : exception; +end On_Vectors; + +12.1 Generic Declarations + +13 December 2012 278 + + Ada Reference Manual — 2012 Edition + +12.2 Generic Bodies + +The body of a generic unit (a generic body) is a template for the instance bodies. The syntax of a generic +body is identical to that of a nongeneric body. + +Dynamic Semantics + +The elaboration of a generic body has no other effect than to establish that the generic unit can from then +on be instantiated without failing the Elaboration_Check. If the generic body is a child of a generic +package, then its elaboration establishes that each corresponding declaration nested in an instance of the +parent (see 10.1.1) can from then on be instantiated without failing the Elaboration_Check. + +NOTES +4 The syntax of generic subprograms implies that a generic subprogram body is always the completion of a declaration. + +Example of a generic procedure body: + +Examples + +procedure Exchange(U, V : in out Elem) is -- see 12.1 + T : Elem; -- the generic formal type +begin + T := U; + U := V; + V := T; +end Exchange; + +Example of a generic function body: + +function Squaring(X : Item) return Item is -- see 12.1 +begin + return X*X; -- the formal operator "*" +end Squaring; + +Example of a generic package body: + +package body On_Vectors is -- see 12.1 + function Sum(A, B : Vector) return Vector is + Result : Vector(A'Range); -- the formal type Vector + Bias : constant Integer := B'First - A'First; + begin + if A'Length /= B'Length then + raise Length_Error; + end if; + for N in A'Range loop + Result(N) := Sum(A(N), B(N + Bias)); -- the formal function Sum + end loop; + return Result; + end Sum; + function Sigma(A : Vector) return Item is + Total : Item := A(A'First); -- the formal type Item + begin + for N in A'First + 1 .. A'Last loop + Total := Sum(Total, A(N)); -- the formal function Sum + end loop; + return Total; + end Sigma; +end On_Vectors; + +1 + +2 + +3 + +4 + +5 + +6 + +7 + +8 + +9 + +10 + +11 + +12 + +279 13 December 2012 + +Generic Bodies 12.2 + + Ada Reference Manual — 2012 Edition + +12.3 Generic Instantiation + +1 + +An instance of a generic unit is declared by a generic_instantiation. + +2/3 + +3 + +4 + +5 + +6 + +7/3 + +8 + +9/3 + +Syntax + +generic_instantiation ::= + package defining_program_unit_name is + new generic_package_name [generic_actual_part] + [aspect_specification]; + | [overriding_indicator] + procedure defining_program_unit_name is + new generic_procedure_name [generic_actual_part] + [aspect_specification]; + | [overriding_indicator] + function defining_designator is + new generic_function_name [generic_actual_part] + [aspect_specification]; + +generic_actual_part ::= + (generic_association {, generic_association}) + +generic_association ::= + [generic_formal_parameter_selector_name =>] explicit_generic_actual_parameter + +explicit_generic_actual_parameter ::= expression | variable_name + | subprogram_name | entry_name | subtype_mark + | package_instance_name + +A generic_association is named or positional according to whether or not the generic_formal_- +parameter_selector_name is specified. Any positional associations shall precede any named +associations. + +The generic actual parameter is either the explicit_generic_actual_parameter given in a generic_- +association for each formal, or the corresponding default_expression or default_name if no generic_- +association is given for the formal. When the meaning is clear from context, the term “generic actual,” or +simply “actual,” is used as a synonym for “generic actual parameter” and also for the view denoted by one, +or the value of one. + +Legality Rules + +In a generic_instantiation for a particular kind of program unit (package, procedure, or function), the +name shall denote a generic unit of the corresponding kind (generic package, generic procedure, or +generic function, respectively). + +The generic_formal_parameter_selector_name of a named generic_association shall denote a +generic_formal_parameter_declaration of the generic unit being instantiated. If two or more formal +subprograms have the same defining name, then named associations are not allowed for the corresponding +actuals. + +9.1/3 + +The generic_formal_parameter_declaration for a positional generic_association is the parameter with +the corresponding position in the generic_formal_part of the generic unit being instantiated. + +10 + +A generic_instantiation shall contain at most one generic_association for each formal. Each formal +without an association shall have a default_expression or subprogram_default. + +12.3 Generic Instantiation + +13 December 2012 280 + + Ada Reference Manual — 2012 Edition + +In a generic unit Legality Rules are enforced at compile time of the generic_declaration and generic body, +given the properties of the formals. In the visible part and formal part of an instance, Legality Rules are +enforced at compile time of the generic_instantiation, given the properties of the actuals. In other parts of +an instance, Legality Rules are not enforced; this rule does not apply when a given rule explicitly specifies +otherwise. + +Static Semantics + +A generic_instantiation declares an instance; it is equivalent to the instance declaration (a package_- +declaration or subprogram_declaration) immediately followed by the instance body, both at the place of +the instantiation. + +The instance is a copy of the text of the template. Each use of a formal parameter becomes (in the copy) a +use of the actual, as explained below. An instance of a generic package is a package, that of a generic +procedure is a procedure, and that of a generic function is a function. + +The interpretation of each construct within a generic declaration or body is determined using the +overloading rules when that generic declaration or body is compiled. In an instance, the interpretation of +each (copied) construct is the same, except in the case of a name that denotes the generic_declaration or +some declaration within the generic unit; the corresponding name in the instance then denotes the +corresponding copy of the denoted declaration. The overloading rules do not apply in the instance. + +In an instance, a generic_formal_parameter_declaration declares a view whose properties are identical to +those of the actual, except as specified in 12.4, “Formal Objects” and 12.6, “Formal Subprograms”. +Similarly, for a declaration within a generic_formal_parameter_declaration, +the corresponding +declaration in an instance declares a view whose properties are identical to the corresponding declaration +within the declaration of the actual. + +Implicit declarations are also copied, and a name that denotes an implicit declaration in the generic +denotes the corresponding copy in the instance. However, for a type declared within the visible part of the +generic, a whole new set of primitive subprograms is implicitly declared for use outside the instance, and +may differ from the copied set if the properties of the type in some way depend on the properties of some +actual type specified in the instantiation. For example, if the type in the generic is derived from a formal +private type, then in the instance the type will inherit subprograms from the corresponding actual type. + +These new implicit declarations occur immediately after the type declaration in the instance, and override +the copied ones. The copied ones can be called only from within the instance; the new ones can be called +only from outside the instance, although for tagged types, the body of a new one can be executed by a call +to an old one. + +In the visible part of an instance, an explicit declaration overrides an implicit declaration if they are +homographs, as described in 8.3. On the other hand, an explicit declaration in the private part of an +instance overrides an implicit declaration in the instance, only if the corresponding explicit declaration in +the generic overrides a corresponding implicit declaration in the generic. Corresponding rules apply to the +other kinds of overriding described in 8.3. + +Post-Compilation Rules + +Recursive generic instantiation is not allowed in the following sense: if a given generic unit includes an +instantiation of a second generic unit, then the instance generated by this instantiation shall not include an +instance of the first generic unit (whether this instance is generated directly, or indirectly by intermediate +instantiations). + +11 + +12 + +13 + +14 + +15 + +16 + +17 + +18 + +19 + +281 13 December 2012 + +Generic Instantiation 12.3 + + Ada Reference Manual — 2012 Edition + +20 + +21 + +22 + +23 + +24 + +25 + +26 + +27 + +28 + +29 + +Dynamic Semantics + +For the elaboration of a generic_instantiation, each generic_association is first evaluated. If a default is +used, an implicit generic_association is assumed for this rule. These evaluations are done in an arbitrary +order, except that the evaluation for a default actual takes place after the evaluation for another actual if +the default includes a name that denotes the other one. Finally, the instance declaration and body are +elaborated. + +For the evaluation of a generic_association the generic actual parameter is evaluated. Additional actions +are performed in the case of a formal object of mode in (see 12.4). + +NOTES +5 If a formal type is not tagged, then the type is treated as an untagged type within the generic body. Deriving from such a +type in a generic body is permitted; the new type does not get a new tag value, even if the actual is tagged. Overriding +operations for such a derived type cannot be dispatched to from outside the instance. + +Examples of generic instantiations (see 12.1): + +Examples + +procedure Swap is new Exchange(Elem => Integer); +procedure Swap is new Exchange(Character); +-- Swap is overloaded +function Square is new Squaring(Integer); +-- "*" of Integer used by default +function Square is new Squaring(Item => Matrix, "*" => Matrix_Product); +function Square is new Squaring(Matrix, Matrix_Product); -- same as previous +package Int_Vectors is new On_Vectors(Integer, Table, "+"); + +Examples of uses of instantiated units: + +Swap(A, B); +A := Square(A); + +T : Table(1 .. 5) := (10, 20, 30, 40, 50); +N : Integer := Int_Vectors.Sigma(T); -- 150 (see 12.2, “Generic Bodies” for the body of +Sigma) +use Int_Vectors; +M : Integer := Sigma(T); -- 150 + +12.4 Formal Objects + +1 + +A generic formal object can be used to pass a value or variable to a generic unit. + +2/3 + +3 + +4 + +5/2 + +Syntax + +formal_object_declaration ::= + defining_identifier_list : mode [null_exclusion] subtype_mark [:= default_expression] + [aspect_specification]; + | defining_identifier_list : mode access_definition [:= default_expression] + [aspect_specification]; + +Name Resolution Rules + +The expected type for the default_expression, if any, of a formal object is the type of the formal object. + +For a generic formal object of mode in, the expected type for the actual is the type of the formal. + +For a generic formal object of mode in out, the type of the actual shall resolve to the type determined by +the subtype_mark, or for a formal_object_declaration with an access_definition, to a specific anonymous +access type. If the anonymous access type is an access-to-object type, the type of the actual shall have the +same designated type as that of the access_definition. If the anonymous access type is an access-to- + +12.3 Generic Instantiation + +13 December 2012 282 + + Ada Reference Manual — 2012 Edition + +subprogram type, the type of the actual shall have a designated profile which is type conformant with that +of the access_definition. + +Legality Rules + +If a generic formal object has a default_expression, then the mode shall be in (either explicitly or by +default); otherwise, its mode shall be either in or in out. + +For a generic formal object of mode in, the actual shall be an expression. For a generic formal object of +mode in out, the actual shall be a name that denotes a variable for which renaming is allowed (see 8.5.1). + +In the case where the type of the formal is defined by an access_definition, the type of the actual and the +type of the formal: + +• shall both be access-to-object types with statically matching designated subtypes and with both + +or neither being access-to-constant types; or + +• shall both be access-to-subprogram types with subtype conformant designated profiles. + +For a formal_object_declaration with a null_exclusion or an access_definition that has a null_exclusion: + +• + +if the actual matching the formal_object_declaration denotes the generic formal object of +another generic unit G, and the instantiation containing the actual occurs within the body of G or +within the body of a generic unit declared within the declarative region of G, then the +declaration of the formal object of G shall have a null_exclusion; + +• otherwise, the subtype of the actual matching the formal_object_declaration shall exclude null. +In addition to the places where Legality Rules normally apply (see 12.3), this rule applies also in +the private part of an instance of a generic unit. + +Static Semantics + +A formal_object_declaration declares a generic formal object. The default mode is in. For a formal object +of mode in, the nominal subtype is the one denoted by the subtype_mark or access_definition in the +declaration of the formal. For a formal object of mode in out, its type is determined by the subtype_mark +or access_definition in the declaration; its nominal subtype is nonstatic, even if the subtype_mark +denotes a static subtype; for a composite type, its nominal subtype is unconstrained if the first subtype of +the type is unconstrained, even if the subtype_mark denotes a constrained subtype. + +In an instance, a formal_object_declaration of mode in is a full constant declaration and declares a new +stand-alone +a +formal_object_declaration of mode in out declares a view whose properties are identical to those of the +actual. + +constant object whose + +actual, whereas + +initialization + +expression + +the + +is + +Dynamic Semantics + +For the evaluation of a generic_association for a formal object of mode in, a constant object is created, +the value of the actual parameter is converted to the nominal subtype of the formal object, and assigned to +the object, including any value adjustment — see 7.6. + +NOTES +6 The constraints that apply to a generic formal object of mode in out are those of the corresponding generic actual +parameter (not those implied by the subtype_mark that appears in the formal_object_declaration). Therefore, to avoid +confusion, it is recommended that the name of a first subtype be used for the declaration of such a formal object. + +283 13 December 2012 + +Formal Objects 12.4 + +6 + +7 + +8/2 + +8.1/2 + +8.2/2 + +8.3/2 + +8.4/2 + +8.5/2 + +9/2 + +10/2 + +11 + +12 + + Ada Reference Manual — 2012 Edition + +12.5 Formal Types + +1/2 + +A generic formal subtype can be used to pass to a generic unit a subtype whose type is in a certain +category of types. + +2/3 + +2.1/3 + +2.2/3 + +3/2 + +4 + +5 + +6/3 + +formal_type_declaration ::= + formal_complete_type_declaration + | formal_incomplete_type_declaration + +Syntax + +formal_complete_type_declaration ::= + type defining_identifier[discriminant_part] is formal_type_definition + [aspect_specification]; + +formal_incomplete_type_declaration ::= + type defining_identifier[discriminant_part] [is tagged]; + +formal_type_definition ::= + formal_private_type_definition + | formal_derived_type_definition + | formal_discrete_type_definition + | formal_signed_integer_type_definition + | formal_modular_type_definition + | formal_floating_point_definition + | formal_ordinary_fixed_point_definition + | formal_decimal_fixed_point_definition + | formal_array_type_definition + | formal_access_type_definition + | formal_interface_type_definition + +For a generic formal subtype, the actual shall be a subtype_mark; it denotes the (generic) actual subtype. + +Legality Rules + +A formal_type_declaration declares a (generic) formal type, and its first subtype, the (generic) formal +subtype. + +Static Semantics + +The form of a formal_type_definition determines a category (of types) to which the formal type belongs. +For a formal_private_type_definition the reserved words tagged and limited indicate the category of types +(see 12.5.1). The +a +formal_incomplete_type_declaration. For a formal_derived_type_definition the category of types is the +derivation class rooted at the ancestor type. For other formal types, the name of the syntactic category +indicates the category of types; a formal_discrete_type_definition defines a discrete type, and so on. + +reserved word + +also plays + +case of + +tagged + +role + +this + +the + +in + +7/2 + +The actual type shall be in the category determined for the formal. + +Legality Rules + +8/3 + +The formal type also belongs to each category that contains the determined category. The primitive +subprograms of the type are as for any type in the determined category. For a formal type other than a +formal derived type, these are the predefined operators of the type. For an elementary formal type, the +predefined operators are implicitly declared immediately after the declaration of the formal type. For a + +Static Semantics + +12.5 Formal Types + +13 December 2012 284 + + Ada Reference Manual — 2012 Edition + +composite formal type, the predefined operators are implicitly declared either immediately after the +declaration of the formal type, or later immediately within the declarative region in which the type is +declared according to the rules of 7.3.1. In an instance, the copy of such an implicit declaration declares a +view of the predefined operator of the actual type, even if this operator has been overridden for the actual +type and even if it is never declared for the actual type. The rules specific to formal derived types are +given in 12.5.1. + +NOTES +7 Generic formal types, like all types, are not named. Instead, a name can denote a generic formal subtype. Within a +generic unit, a generic formal type is considered as being distinct from all other (formal or nonformal) types. + +8 A discriminant_part is allowed only for certain kinds of types, and therefore only for certain kinds of generic formal +types. See 3.7. + +Examples of generic formal types: + +Examples + +type Item is private; +type Buffer(Length : Natural) is limited private; +type Enum is (<>); +type Int is range <>; +type Angle is delta <>; +type Mass is digits <>; +type Table is array (Enum) of Item; + +Example of a generic formal part declaring a formal integer type: + +generic + type Rank is range <>; + First : Rank := Rank'First; + Second : Rank := First + 1; -- the operator "+" of the type Rank + +12.5.1 Formal Private and Derived Types + +In its most general form, the category determined for a formal private type is all types, but the category +can be restricted to only nonlimited types or to only tagged types. Similarly, the category for a formal +incomplete type is all types but the category can be restricted to only tagged types; unlike other formal +types, the actual type does not need to be able to be frozen (see 13.14). The category determined for a +formal derived type is the derivation class rooted at the ancestor type. + +formal_private_type_definition ::= [[abstract] tagged] [limited] private + +formal_derived_type_definition ::= + [abstract] [limited | synchronized] new subtype_mark [[and interface_list]with private] + +Syntax + +Legality Rules + +If a generic formal type declaration has a known_discriminant_part, then it shall not include a +default_expression for a discriminant. + +The ancestor subtype of a formal derived type is the subtype denoted by the subtype_mark of the +formal_derived_type_definition. For a formal derived type declaration, the reserved words with private +shall appear if and only if the ancestor type is a tagged type; in this case the formal derived type is a +private extension of the ancestor type and the ancestor shall not be a class-wide type. Similarly, an +interface_list or the optional reserved words abstract or synchronized shall appear only if the ancestor +type is a tagged type. The reserved word limited or synchronized shall appear only if the ancestor type + +285 13 December 2012 + +Formal Types 12.5 + +9 + +10 + +11 + +12 + +13 + +14 + +15 + +16 + +1/3 + +2 + +3/2 + +4 + +5/3 + + Ada Reference Manual — 2012 Edition + +and any progenitor types are limited types. The reserved word synchronized shall appear (rather than +limited) if the ancestor type or any of the progenitor types are synchronized interfaces. The ancestor type +shall be a limited interface if the reserved word synchronized appears. + +5.1/3 + +The actual type for a formal derived type shall be a descendant of the ancestor type and every progenitor +of the formal type. If the formal type is nonlimited, the actual type shall be nonlimited. If the reserved +word synchronized appears in the declaration of the formal derived type, the actual type shall be a +synchronized tagged type. + +6/3 + +If a formal private or derived subtype is definite, then the actual subtype shall also be definite. + +6.1/3 + +A formal_incomplete_type_declaration declares a formal incomplete type. The only view of a formal +incomplete type is an incomplete view. Thus, a formal incomplete type is subject to the same usage +restrictions as any other incomplete type — see 3.10.1. + +7 + +8 + +9 + +10 + +For a generic formal derived type with no discriminant_part: + +• If the ancestor subtype is constrained, the actual subtype shall be constrained, and shall be + +statically compatible with the ancestor; + +• If the ancestor subtype is an unconstrained access or composite subtype, the actual subtype shall + +be unconstrained. + +• If the ancestor subtype is an unconstrained discriminated subtype, then the actual shall have the +same number of discriminants, and each discriminant of the actual shall correspond to a +discriminant of the ancestor, in the sense of 3.7. + +10.1/2 + +• If the ancestor subtype is an access subtype, the actual subtype shall exclude null if and only if + +the ancestor subtype excludes null. + +11/3 + +The declaration of a formal derived type shall not have a known_discriminant_part. For a generic formal +private or incomplete type with a known_discriminant_part: + +12 + +13 + +14 + +15 + +16/2 + +17/2 + +• The actual type shall be a type with the same number of discriminants. +• The actual subtype shall be unconstrained. +• The subtype of each discriminant of the actual type shall statically match the subtype of the + +corresponding discriminant of the formal type. + +For a generic formal type with an unknown_discriminant_part, the actual may, but need not, have +discriminants, and may be definite or indefinite. + +The category determined for a formal private type is as follows: + +Type Definition + +Determined Category + +Static Semantics + +limited private +private +tagged limited private +tagged private + +the category of all types +the category of all nonlimited types +the category of all tagged types +the category of all nonlimited tagged types + +18 + +The presence of the reserved word abstract determines whether the actual type may be abstract. + +18.1/3 + +The category determined for a formal incomplete type is the category of all types, unless the +formal_type_declaration includes the reserved word tagged; in this case, it is the category of all tagged +types. + +12.5.1 Formal Private and Derived Types + +13 December 2012 286 + + + Ada Reference Manual — 2012 Edition + +A formal private or derived type is a private or derived type, respectively. A formal derived tagged type is +a private extension. A formal private or derived type is abstract if the reserved word abstract appears in its +declaration. + +For a formal derived type, the characteristics (including components, but excluding discriminants if there +is a new discriminant_part), predefined operators, and inherited user-defined primitive subprograms are +determined by its ancestor type and its progenitor types (if any), in the same way that those of a derived +type are determined by those of its parent type and its progenitor types (see 3.4 and 7.3.1). + +In an instance, the copy of an implicit declaration of a primitive subprogram of a formal derived type +declares a view of the corresponding primitive subprogram of the ancestor or progenitor of the formal +derived type, even if this primitive has been overridden for the actual type and even if it is never declared +for the actual type. When the ancestor or progenitor of the formal derived type is itself a formal type, the +copy of the implicit declaration declares a view of the corresponding copied operation of the ancestor or +progenitor. In the case of a formal private extension, however, the tag of the formal type is that of the +actual type, so if the tag in a call is statically determined to be that of the formal type, the body executed +will be that corresponding to the actual type. + +For a prefix S that denotes a formal indefinite subtype, the following attribute is defined: + +S'Definite + +S'Definite yields True if the actual subtype corresponding to S is definite; otherwise, it +yields False. The value of this attribute is of the predefined type Boolean. + +Dynamic Semantics + +In the case where a formal type has unknown discriminants, and the actual type is a class-wide type +T'Class: + +• For the purposes of defining the primitive operations of the formal type, each of the primitive +operations of the actual type is considered to be a subprogram (with an intrinsic calling +convention — see 6.3.1) whose body consists of a dispatching call upon the corresponding +operation of T, with its formal parameters as the actual parameters. If it is a function, the result +of the dispatching call is returned. + +• If the corresponding operation of T has no controlling formal parameters, then the controlling tag +value is determined by the context of the call, according to the rules for tag-indeterminate calls +(see 3.9.2 and 5.2). In the case where the tag would be statically determined to be that of the +formal type, the call raises Program_Error. If such a function is renamed, any call on the +renaming raises Program_Error. + +NOTES +9 In accordance with the general rule that the actual type shall belong to the category determined for the formal (see 12.5, +“Formal Types”): + +If the formal type is nonlimited, then so shall be the actual; + +• +• For a formal derived type, the actual shall be in the class rooted at the ancestor subtype. + +10 The actual type can be abstract only if the formal type is abstract (see 3.9.3). + +11 If the formal has a discriminant_part, the actual can be either definite or indefinite. Otherwise, the actual has to be +definite. + +19 + +20/3 + +21/3 + +22/1 + +23/3 + +23.1/3 + +23.2/2 + +23.3/2 + +24/2 + +25 + +26 + +27 + +28 + +287 13 December 2012 + +Formal Private and Derived Types 12.5.1 + + Ada Reference Manual — 2012 Edition + +12.5.2 Formal Scalar Types + +1/2 + +A formal scalar type is one defined by any of the formal_type_definitions in this subclause. The category +determined for a formal scalar type is the category of all discrete, signed integer, modular, floating point, +ordinary fixed point, or decimal types. + +2 + +3 + +4 + +5 + +6 + +7 + +8 + +9 + +Syntax + +formal_discrete_type_definition ::= (<>) + +formal_signed_integer_type_definition ::= range <> + +formal_modular_type_definition ::= mod <> + +formal_floating_point_definition ::= digits <> + +formal_ordinary_fixed_point_definition ::= delta <> + +formal_decimal_fixed_point_definition ::= delta <> digits <> + +The actual type for a formal scalar type shall not be a nonstandard numeric type. + +Legality Rules + +NOTES +12 The actual type shall be in the class of types implied by the syntactic category of the formal type definition (see 12.5, +“Formal Types”). For example, the actual for a formal_modular_type_definition shall be a modular type. + +12.5.3 Formal Array Types + +1/2 + +The category determined for a formal array type is the category of all array types. + +formal_array_type_definition ::= array_type_definition + +Syntax + +Legality Rules + +The only form of discrete_subtype_definition that is allowed within the declaration of a generic formal +(constrained) array subtype is a subtype_mark. + +For a formal array subtype, the actual subtype shall satisfy the following conditions: + +• The formal array type and the actual array type shall have the same dimensionality; the formal + +subtype and the actual subtype shall be either both constrained or both unconstrained. + +• For each index position, the index types shall be the same, and the index subtypes (if + +unconstrained), or the index ranges (if constrained), shall statically match (see 4.9.1). + +• The component subtypes of the formal and actual array types shall statically match. +• If the formal type has aliased components, then so shall the actual. + +2 + +3 + +4 + +5 + +6 + +7 + +8 + +9 + +10 + +Example of formal array types: +-- given the generic package + +Examples + +12.5.2 Formal Scalar Types + +13 December 2012 288 + + Ada Reference Manual — 2012 Edition + +generic + type Item is private; + type Index is (<>); + type Vector is array (Index range <>) of Item; + type Table is array (Index) of Item; +package P is + ... +end P; +-- and the types +type Mix is array (Color range <>) of Boolean; +type Option is array (Color) of Boolean; +-- then Mix can match Vector and Option can match Table +package R is new P(Item => Boolean, Index => Color, + Vector => Mix, Table => Option); +-- Note that Mix cannot match Table and Option cannot match Vector + +12.5.4 Formal Access Types + +The category determined for a formal access type is the category of all access types. + +formal_access_type_definition ::= access_type_definition + +Syntax + +Legality Rules + +For a formal access-to-object type, the designated subtypes of the formal and actual types shall statically +match. + +If and only if the general_access_modifier constant applies to the formal, the actual shall be an access- +to-constant type. If the general_access_modifier all applies to the formal, then the actual shall be a +general access-to-variable type (see 3.10). If and only if the formal subtype excludes null, the actual +subtype shall exclude null. + +11 + +12 + +13 + +14 + +15 + +16 + +1/2 + +2 + +3 + +4/2 + +For a formal access-to-subprogram subtype, the designated profiles of the formal and the actual shall be +subtype conformant. + +5/3 + +Example of formal access types: + +Examples + +-- the formal types of the generic package +generic + type Node is private; + type Link is access Node; +package P is + ... +end P; +-- can be matched by the actual types +type Car; +type Car_Name is access Car; +type Car is + record + Pred, Succ : Car_Name; + Number : License_Number; + Owner : Person; + end record; +-- in the following generic instantiation + +6 + +7 + +8 + +9 + +10 + +11 + +12 + +289 13 December 2012 + +Formal Array Types 12.5.3 + + Ada Reference Manual — 2012 Edition + +13 + +package R is new P(Node => Car, Link => Car_Name); + +12.5.5 Formal Interface Types + +1/2 + +The category determined for a formal interface type is the category of all interface types. + +2/2 + +3/2 + +4/2 + +5/2 + +6/2 + +formal_interface_type_definition ::= interface_type_definition + +Syntax + +The actual type shall be a descendant of every progenitor of the formal type. + +Legality Rules + +The actual type shall be a limited, task, protected, or synchronized interface if and only if the formal type +is also, respectively, a limited, task, protected, or synchronized interface. + +Examples +type Root_Work_Item is tagged private; +generic + type Managed_Task is task interface; + type Work_Item(<>) is new Root_Work_Item with private; +package Server_Manager is + task type Server is new Managed_Task with + entry Start(Data : in out Work_Item); + end Server; +end Server_Manager; + +7/2 + +This generic allows an application to establish a standard interface that all tasks need to implement so they +can be managed appropriately by an application-specific scheduler. + +12.6 Formal Subprograms + +1 + +Formal subprograms can be used to pass callable entities to a generic unit. + +2/2 + +2.1/3 + +2.2/3 + +3/2 + +4 + +4.1/2 + +5 + +6 + +formal_subprogram_declaration ::= formal_concrete_subprogram_declaration + | formal_abstract_subprogram_declaration + +Syntax + +formal_concrete_subprogram_declaration ::= + with subprogram_specification [is subprogram_default] + [aspect_specification]; + +formal_abstract_subprogram_declaration ::= + with subprogram_specification is abstract [subprogram_default] + [aspect_specification]; + +subprogram_default ::= default_name | <> | null + +default_name ::= name + +A subprogram_default of null shall not be specified for a formal function or for a +formal_abstract_subprogram_declaration. + +The expected profile for the default_name, if any, is that of the formal subprogram. + +Name Resolution Rules + +For a generic formal subprogram, the expected profile for the actual is that of the formal subprogram. + +12.5.4 Formal Access Types + +13 December 2012 290 + + Ada Reference Manual — 2012 Edition + +The profiles of the formal and any named default shall be mode conformant. + +The profiles of the formal and actual shall be mode conformant. + +Legality Rules + +7/3 + +8/3 + +For a parameter or result subtype of a formal_subprogram_declaration that has an explicit null_exclusion: + +8.1/2 + +• + +if the actual matching the formal_subprogram_declaration denotes a generic formal object of +another generic unit G, and the instantiation containing the actual that occurs within the body of +a generic unit G or within the body of a generic unit declared within the declarative region of the +generic unit G, then the corresponding parameter or result type of the formal subprogram of G +shall have a null_exclusion; + +• otherwise, the subtype of the corresponding parameter or result type of the actual matching the +formal_subprogram_declaration shall exclude null. In addition to the places where Legality +Rules normally apply (see 12.3), this rule applies also in the private part of an instance of a +generic unit. + +If a formal parameter of a formal_abstract_subprogram_declaration is of a specific tagged type T or of +an anonymous access type designating a specific tagged type T, T is called a controlling type of the +formal_abstract_subprogram_declaration. Similarly, if the result of a formal_abstract_subprogram_- +declaration for a function is of a specific tagged type T or of an anonymous access type designating a +specific tagged type T, T is called a controlling type of the formal_abstract_subprogram_declaration. A +formal_abstract_subprogram_declaration shall have exactly one controlling type, and that type shall not +be incomplete. + +8.2/2 + +8.3/2 + +8.4/3 + +The actual subprogram for a formal_abstract_subprogram_declaration shall be a dispatching operation of +the controlling type or of the actual type corresponding to the controlling type. + +8.5/2 + +Static Semantics + +A formal_subprogram_declaration declares a generic formal subprogram. The types of the formal +parameters and result, if any, of the formal subprogram are those determined by the subtype_marks given +in the formal_subprogram_declaration; however, independent of the particular subtypes that are denoted +by the subtype_marks, the nominal subtypes of the formal parameters and result, if any, are defined to be +nonstatic, and unconstrained if of an array type (no applicable index constraint is provided in a call on a +formal subprogram). In an instance, a formal_subprogram_declaration declares a view of the actual. The +profile of this view takes its subtypes and calling convention from the original profile of the actual entity, +while taking the formal parameter names and default_expressions from the profile given in the formal_- +subprogram_declaration. The view is a function or procedure, never an entry. + +If a subtype_mark in the profile of the formal_subprogram_declaration denotes a formal private or +formal derived type and the actual type for this formal type is a class-wide type T'Class, then for the +purposes of resolving the corresponding actual subprogram at the point of the instantiation, certain implicit +declarations may be available as possible resolutions as follows: + +For each primitive subprogram of T that is directly visible at the point of the instantiation, and +that has at least one controlling formal parameter, a corresponding implicitly declared +subprogram with the same defining name, and having the same profile as the primitive +subprogram except that T is systematically replaced by T'Class in the types of its profile, is +potentially use-visible. The body of such a subprogram is as defined in 12.5.1 for primitive +subprograms of a formal type when the actual type is class-wide. + +9 + +9.1/3 + +9.2/3 + +291 13 December 2012 + +Formal Subprograms 12.6 + + Ada Reference Manual — 2012 Edition + +10 + +If a generic unit has a subprogram_default specified by a box, and the corresponding actual parameter is +omitted, then it is equivalent to an explicit actual parameter that is a usage name identical to the defining +name of the formal. + +10.1/2 + +If a generic unit has a subprogram_default specified by the reserved word null, and the corresponding +actual parameter is omitted, then it is equivalent to an explicit actual parameter that is a null procedure +having the profile given in the formal_subprogram_declaration. + +10.2/2 + +The subprogram declared by a formal_abstract_subprogram_declaration with a controlling type T is a +dispatching operation of type T. + +11 + +12 + +13 + +14 + +15 + +16/2 + +16.1/2 + +NOTES +13 The matching rules for formal subprograms state requirements +to +subprogram_renaming_declarations (see 8.5.4). In particular, the name of a parameter of the formal subprogram need not +be the same as that of the corresponding parameter of the actual subprogram; similarly, for these parameters, +default_expressions need not correspond. + +that are similar + +those applying + +to + +14 The constraints that apply to a parameter of a formal subprogram are those of the corresponding formal parameter of +the matching actual subprogram (not those implied by the corresponding subtype_mark in the _specification of the formal +subprogram). A similar remark applies to the result of a function. Therefore, to avoid confusion, it is recommended that +the name of a first subtype be used in any declaration of a formal subprogram. + +15 The subtype specified for a formal parameter of a generic formal subprogram can be any visible subtype, including a +generic formal subtype of the same generic_formal_part. + +16 A formal subprogram is matched by an attribute of a type if the attribute is a function with a matching specification. +An enumeration literal of a given type matches a parameterless formal function whose result type is the given type. + +17 A default_name denotes an entity that is visible or directly visible at the place of the generic_declaration; a box used +as a default is equivalent to a name that denotes an entity that is directly visible at the place of the _instantiation. + +18 The actual subprogram cannot be abstract unless the formal subprogram is a formal_abstract_subprogram_- +declaration (see 3.9.3). + +19 The subprogram declared by a formal_abstract_subprogram_declaration is an abstract subprogram. All calls on a +subprogram declared by a formal_abstract_subprogram_declaration must be dispatching calls. See 3.9.3. + +16.2/2 + +20 A null procedure as a subprogram default has convention Intrinsic (see 6.3.1). + +17 + +Examples of generic formal subprograms: + +Examples + +18/2 + +19 + +20 + +21 + +22 + +23 + +24 + +with function "+"(X, Y : Item) return Item is <>; +with function Image(X : Enum) return String is Enum'Image; +with procedure Update is Default_Update; +with procedure Pre_Action(X : in Item) is null; -- defaults to no action +with procedure Write(S : not null access Root_Stream_Type'Class; + Desc : Descriptor) + is abstract Descriptor'Write; -- see 13.13.2 +-- Dispatching operation on Descriptor with default +-- given the generic procedure declaration +generic + with procedure Action (X : in Item); +procedure Iterate(Seq : in Item_Sequence); +-- and the procedure +procedure Put_Item(X : in Item); +-- the following instantiation is possible +procedure Put_List is new Iterate(Action => Put_Item); + +12.6 Formal Subprograms + +13 December 2012 292 + + Ada Reference Manual — 2012 Edition + +12.7 Formal Packages + +Formal packages can be used to pass packages to a generic unit. The formal_package_declaration +declares that the formal package is an instance of a given generic package. Upon instantiation, the actual +package has to be an instance of that generic package. + +Syntax + +formal_package_declaration ::= + with package defining_identifier is new generic_package_name formal_package_actual_part + [aspect_specification]; + +formal_package_actual_part ::= + ([others =>] <>) + | [generic_actual_part] + | (formal_package_association {, formal_package_association} [, others => <>]) + +formal_package_association ::= + generic_association + | generic_formal_parameter_selector_name => <> + +Any positional formal_package_associations shall precede any named +formal_package_associations. + +Legality Rules + +1 + +2/3 + +3/2 + +3.1/2 + +3.2/2 + +The generic_package_name shall denote a generic package (the template for the formal package); the +formal package is an instance of the template. + +4 + +The generic_formal_parameter_selector_name of a +formal_package_association shall denote a +generic_formal_parameter_declaration of the template. If two or more formal subprograms of the +template have the same defining name, then named associations are not allowed for the corresponding +actuals. + +A formal_package_actual_part shall contain at most one formal_package_association for each formal +parameter. If the formal_package_actual_part does not include “others => <>”, each formal parameter +without an association shall have a default_expression or subprogram_default. + +The rules for matching between formal_package_associations and the generic formals of the template are +as follows: + +• If all of + +the + +the +explicit_generic_actual_parameters of the formal_package_associations shall be legal for an +instantiation of the template. + +formal_package_associations are given by generic associations, + +• If a formal_package_association for a formal type T of the template is given by <>, then the +formal_package_association for any other generic_formal_parameter_declaration of the +template that mentions T directly or indirectly must be given by <> as well. + +The actual shall be an instance of the template. If the formal_package_actual_part is (<>) or (others => +<>), then the actual may be any instance of the template; otherwise, certain of the actual parameters of the +actual instance shall match the corresponding actual parameters of the formal package, determined as +follows: + +• If the formal_package_actual_part includes generic_associations as well as associations with +<>, then only the actual parameters specified explicitly with generic_associations are required +to match; + +293 13 December 2012 + +Formal Packages 12.7 + +4.1/3 + +4.2/3 + +4.3/3 + +4.4/3 + +4.5/3 + +5/2 + +5.1/2 + + Ada Reference Manual — 2012 Edition + +5.2/2 + +• Otherwise, all actual parameters shall match, whether any actual parameter is given explicitly or + +by default. + +5.3/2 + +The rules for matching of actual parameters between the actual instance and the formal package are as +follows: + +6/2 + +• For a formal object of mode in, the actuals match if they are static expressions with the same + +value, or if they statically denote the same constant, or if they are both the literal null. + +7 + +8 + +8.1/1 + +• For a formal subtype, the actuals match if they denote statically matching subtypes. +• For other kinds of formals, the actuals match if they statically denote the same entity. + +For the purposes of matching, any actual parameter that is the name of a formal object of mode in is +replaced by the formal object's actual expression (recursively). + +9 + +A formal_package_declaration declares a generic formal package. + +Static Semantics + +10/2 + +The visible part of a formal package includes the first list of basic_declarative_items of the package_- +specification. In addition, for each actual parameter that is not required to match, a copy of the declaration +of the corresponding formal parameter of the template is included in the visible part of the formal package. +If the copied declaration is for a formal type, copies of the implicit declarations of the primitive +subprograms of the formal type are also included in the visible part of the formal package. + +11/2 + +For the purposes of matching, if the actual instance A is itself a formal package, then the actual parameters +of A are those specified explicitly or implicitly in the formal_package_actual_part for A, plus, for those +not specified, the copies of the formal parameters of the template included in the visible part of A. + +12/2 + +13/2 + +14/2 + +15/2 + +16/2 + +17/2 + +18/2 + +19/2 + +20/2 + +21/2 + +22/2 + +Examples + +Example of a generic package with formal package parameters: +with Ada.Containers.Ordered_Maps; -- see A.18.6 +generic + with package Mapping_1 is new Ada.Containers.Ordered_Maps(<>); + with package Mapping_2 is new Ada.Containers.Ordered_Maps + (Key_Type => Mapping_1.Element_Type, + others => <>); +package Ordered_Join is + -- Provide a "join" between two mappings + subtype Key_Type is Mapping_1.Key_Type; + subtype Element_Type is Mapping_2.Element_Type; + function Lookup(Key : Key_Type) return Element_Type; + ... +end Ordered_Join; + +Example of an instantiation of a package with formal packages: + +with Ada.Containers.Ordered_Maps; +package Symbol_Package is + type String_Id is ... + type Symbol_Info is ... + package String_Table is new Ada.Containers.Ordered_Maps + (Key_Type => String, + Element_Type => String_Id); + package Symbol_Table is new Ada.Containers.Ordered_Maps + (Key_Type => String_Id, + Element_Type => Symbol_Info); + +12.7 Formal Packages + +13 December 2012 294 + + Ada Reference Manual — 2012 Edition + + package String_Info is new Ordered_Join(Mapping_1 => String_Table, + Mapping_2 => Symbol_Table); + Apple_Info : constant Symbol_Info := String_Info.Lookup("Apple"); +end Symbol_Package; + +23/2 + +24/2 + +25/2 + +12.8 Example of a Generic Package + +The following example provides a possible formulation of stacks by means of a generic package. The size +of each stack and the type of the stack elements are provided as generic formal parameters. + +1 + +This paragraph was deleted. + +Examples + +generic + Size : Positive; + type Item is private; +package Stack is + procedure Push(E : in Item); + procedure Pop (E : out Item); + Overflow, Underflow : exception; +end Stack; +package body Stack is + type Table is array (Positive range <>) of Item; + Space : Table(1 .. Size); + Index : Natural := 0; + procedure Push(E : in Item) is + begin + if Index >= Size then + raise Overflow; + end if; + Index := Index + 1; + Space(Index) := E; + end Push; + procedure Pop(E : out Item) is + begin + if Index = 0 then + raise Underflow; + end if; + E := Space(Index); + Index := Index - 1; + end Pop; +end Stack; + +Instances of this generic package can be obtained as follows: + +package Stack_Int is new Stack(Size => 200, Item => Integer); +package Stack_Bool is new Stack(100, Boolean); + +Thereafter, the procedures of the instantiated packages can be called as follows: + +Stack_Int.Push(N); +Stack_Bool.Push(True); + +2/1 + +3 + +4 + +5 + +6 + +7 + +8 + +9 + +10 + +11 + +12 + +295 13 December 2012 + +Formal Packages 12.7 + + 13 +14 + +15 + +16 + +Ada Reference Manual — 2012 Edition + +Alternatively, a generic formulation of the type Stack can be given as follows (package body omitted): + +generic + type Item is private; +package On_Stacks is + type Stack(Size : Positive) is limited private; + procedure Push(S : in out Stack; E : in Item); + procedure Pop (S : in out Stack; E : out Item); + Overflow, Underflow : exception; +private + type Table is array (Positive range <>) of Item; + type Stack(Size : Positive) is + record + Space : Table(1 .. Size); + Index : Natural := 0; + end record; +end On_Stacks; + +In order to use such a package, an instance has to be created and thereafter stacks of the corresponding +type can be declared: +declare + package Stack_Real is new On_Stacks(Real); use Stack_Real; + S : Stack(100); +begin + ... + Push(S, 2.54); + ... +end; + +12.8 Example of a Generic Package + +13 December 2012 296 + + Ada Reference Manual — 2012 Edition + +13 Representation Issues + +This clause describes features for querying and controlling certain aspects of entities and for interfacing to +hardware. + +1/3 + +13.1 Operational and Representation Aspects + +Two kinds of aspects of entities can be specified: representation aspects and operational aspects. +Representation aspects affect how the types and other entities of the language are to be mapped onto the +underlying machine. Operational aspects determine other properties of entities. + +Either kind of aspect of an entity may be specified by means of an aspect_specification (see 13.1.1), +which is an optional element of most kinds of declarations and applies to the entity or entities being +declared. Aspects may also be specified by certain other constructs occurring subsequent to the declaration +of the affected entity: a representation aspect value may be specified by means of a representation item +and an operational aspect value may be specified by means of an operational item. + +There are six kinds of representation items: attribute_definition_clauses for representation attributes, +enumeration_representation_clauses, record_representation_clauses, at_clauses, component_clauses, +and representation pragmas. They can be provided to give more efficient representation or to interface +with features that are outside the domain of the language (for example, peripheral hardware). + +An operational item is an attribute_definition_clause for an operational attribute. + +An operational item or a representation item applies to an entity identified by a local_name, which +denotes an entity declared local to the current declarative region, or a library unit declared immediately +preceding a representation pragma in a compilation. + +Syntax + +aspect_clause ::= attribute_definition_clause + | enumeration_representation_clause + | record_representation_clause + | at_clause + +local_name ::= direct_name + | direct_name'attribute_designator + | library_unit_name + +A representation pragma is allowed only at places where an aspect_clause or compilation_unit is +allowed. + +Name Resolution Rules + +In an operational item or representation item, if the local_name is a direct_name, then it shall resolve to +denote a declaration (or, in the case of a pragma, one or more declarations) that occurs immediately within +the same declarative region as the item. If the local_name has an attribute_designator, then it shall +resolve to denote an implementation-defined component (see 13.5.1) or a class-wide type implicitly +declared immediately within the same declarative region as the item. A local_name that is a +library_unit_name (only permitted in a representation pragma) shall resolve to denote the library_item +that immediately precedes (except for other pragmas) the representation pragma. + +0.1/3 + +0.2/3 + +1/1 + +1.1/1 + +1.2/1 + +2/1 + +3 + +4/1 + +5/1 + +297 13 December 2012 + +Representation Issues 13 + + Ada Reference Manual — 2012 Edition + +Legality Rules + +6/1 + +7/2 + +8/3 + +8.1/3 + +9/3 + +9.1/3 + +The local_name of an aspect_clause or representation pragma shall statically denote an entity (or, in the +case of a pragma, one or more entities) declared immediately preceding it in a compilation, or within the +same declarative_part, package_specification, task_definition, protected_definition, or record_definition +as the representation or operational item. If a local_name denotes a local callable entity, it may do so +through a local subprogram_renaming_declaration (as a way to resolve ambiguity in the presence of +overloading); otherwise, the local_name shall not denote a renaming_declaration. + +The representation of an object consists of a certain number of bits (the size of the object). For an object of +an elementary type, these are the bits that are normally read or updated by the machine code when loading, +storing, or operating-on the value of the object. For an object of a composite type, these are the bits +reserved for this object, and include bits occupied by subcomponents of the object. If the size of an object +is greater than that of its subtype, the additional bits are padding bits. For an elementary object, these +padding bits are normally read and updated along with the others. For a composite object, padding bits +might not be read or updated in any given composite operation, depending on the implementation. + +A representation item directly specifies a representation aspect of the entity denoted by the local_name, +except in the case of a type-related representation item, whose local_name shall denote a first subtype, +and which directly specifies an aspect of the subtype's type. A representation item that names a subtype is +either subtype-specific (Size and Alignment clauses) or type-related (all others). Subtype-specific aspects +may differ for different subtypes of the same type. + +An operational item directly specifies an operational aspect of the entity denoted by the local_name, +except in the case of a type-related operational item, whose local_name shall denote a first subtype, and +which directly specifies an aspect of the type of the subtype. + +A representation item that directly specifies an aspect of a subtype or type shall appear after the type is +completely defined (see 3.11.1), and before the subtype or type is frozen (see 13.14). If a representation +item or aspect_specification is given that directly specifies an aspect of an entity, then it is illegal to give +another representation item or aspect_specification that directly specifies the same aspect of the entity. + +An operational item that directly specifies an aspect of an entity shall appear before the entity is frozen +(see 13.14). If an operational item or aspect_specification is given that directly specifies an aspect of an +entity, then it is illegal to give another operational item or aspect_specification that directly specifies the +same aspect of the entity. + +9.2/3 + +Unless otherwise specified, it is illegal to specify an operational or representation aspect of a generic +formal parameter. + +10/3 + +11/3 + +12/3 + +For an untagged derived type, it is illegal to specify a type-related representation aspect if the parent type +is a by-reference type, or has any user-defined primitive subprograms. + +Operational and representation aspects of a generic formal parameter are the same as those of the actual. +Operational and representation aspects are the same for all views of a type. Specification of a type-related +representation aspect is not allowed for a descendant of a generic formal untagged type. + +The specification of the Size aspect for a given subtype, or the size or storage place for an object +(including a component) of a given subtype, shall allow for enough storage space to accommodate any +value of the subtype. + +13/3 + +If a specification of a representation or operational aspect is not supported by the implementation, it is +illegal or raises an exception at run time. + +13.1 Operational and Representation Aspects + +13 December 2012 298 + + Ada Reference Manual — 2012 Edition + +A type_declaration is illegal if it has one or more progenitors, and a nonconfirming value was specified +for a representation aspect of an ancestor, and this conflicts with the representation of some other ancestor. +The cases that cause conflicts are implementation defined. + +13.1/3 + +Static Semantics + +If two subtypes statically match, then their subtype-specific aspects (Size and Alignment) are the same. + +A derived type inherits each type-related representation aspect of its parent type that was directly specified +before the declaration of the derived type, or (in the case where the parent is derived) that was inherited by +the parent type from the grandparent type. A derived subtype inherits each subtype-specific representation +aspect of its parent subtype that was directly specified before the declaration of the derived type, or (in the +case where the parent is derived) that was inherited by the parent subtype from the grandparent subtype, +but only if the parent subtype statically matches the first subtype of the parent type. An inherited +representation aspect is overridden by a subsequent aspect_specification or representation item that +specifies a different value for the same aspect of the type or subtype. + +14 + +15/3 + +In contrast, whether operational aspects are inherited by a derived type depends on each specific aspect; +unless specified, an operational aspect is not inherited. When operational aspects are inherited by a derived +type, aspects that were directly specified by aspect_specifications or operational items that are visible at +the point of the derived type declaration, or (in the case where the parent is derived) that were inherited by +the parent type from the grandparent type are inherited. An inherited operational aspect is overridden by a +subsequent aspect_specification or operational item that specifies the same aspect of the type. + +15.1/3 + +When an aspect that is a subprogram is inherited, the derived type inherits the aspect in the same way that +a derived type inherits a user-defined primitive subprogram from its parent (see 3.4). + +15.2/2 + +Each aspect of representation of an entity is as follows: + +• If the aspect is specified for the entity, meaning that it is either directly specified or inherited, +then that aspect of the entity is as specified, except in the case of Storage_Size, which specifies a +minimum. + +• If an aspect of representation of an entity is not specified, it is chosen by default in an + +unspecified manner. + +If an operational aspect is specified for an entity (meaning that it is either directly specified or inherited), +then that aspect of the entity is as specified. Otherwise, the aspect of the entity has the default value for +that aspect. + +An aspect_specification or representation item that specifies a representation aspect that would have been +chosen in the absence of the aspect_specification or representation item is said to be confirming. The +aspect value specified in this case is said to be a confirming representation aspect value. Other values of +the aspect are said to be nonconfirming, as are the aspect_specifications and representation items that +specified them. + +For the elaboration of an aspect_clause, any evaluable constructs within it are evaluated. + +Dynamic Semantics + +Implementation Permissions + +An implementation may interpret representation aspects in an implementation-defined manner. An +implementation may place implementation-defined restrictions on the specification of representation +aspects. A recommended level of support is defined for the specification of representation aspects and +to requirements for +related features + +in each subclause. These recommendations are changed + +16 + +17 + +18 + +18.1/1 + +18.2/3 + +19/1 + +20/3 + +299 13 December 2012 + +Operational and Representation Aspects 13.1 + + Ada Reference Manual — 2012 Edition + +implementations that support the Systems Programming Annex (see C.2, “Required Representation +Support”). + +Implementation Advice + +21/3 + +The recommended level of support for the specification of all representation aspects is qualified as +follows: + +21.1/3 + +22/3 + +• A confirming specification for a representation aspect should be supported. +• An implementation need not support the specification for a representation aspect that contains +nonstatic expressions, unless each nonstatic expression is a name that statically denotes a +constant declared before the entity. + +23 + +24/3 + +25/3 + +26/3 + +• An implementation need not support a specification for the Size for a given composite subtype, +nor the size or storage place for an object (including a component) of a given composite subtype, +unless the constraints on the subtype and its composite subcomponents (if any) are all static +constraints. + +• An implementation need not support specifying a nonconfirming representation aspect value if it +could cause an aliased object or an object of a by-reference type to be allocated at a +nonaddressable location or, when the alignment attribute of the subtype of such an object is +nonzero, at an address that is not an integral multiple of that alignment. + +• An implementation need not support specifying a nonconfirming representation aspect value if it +could cause an aliased object of an elementary type to have a size other than that which would +have been chosen by default. + +• An implementation need not support specifying a nonconfirming representation aspect value if it +could cause an aliased object of a composite type, or an object whose type is by-reference, to +have a size smaller than that which would have been chosen by default. + +27/3 + +• An implementation need not support specifying a nonconfirming subtype-specific representation + +aspect value for an indefinite or abstract subtype. + +28/3 + +For purposes of these rules, the determination of whether specifying a representation aspect value for a +type could cause an object to have some property is based solely on the properties of the type itself, not on +any available information about how the type is used. In particular, it presumes that minimally aligned +objects of this type might be declared at some point. + +29/3 + +NOTES +1 Aspects that can be specified are defined throughout this International Standard, and are summarized in K.1. + +13.1.1 Aspect Specifications + +Certain representation or operational aspects of an entity may be specified as part of its declaration using +an aspect_specification, rather than using a separate representation or operational item. The declaration +with the aspect_specification is termed the associated declaration. + +Syntax + +aspect_specification ::= + with aspect_mark [=> aspect_definition] {, + aspect_mark [=> aspect_definition] } + +aspect_mark ::= aspect_identifier['Class] + +aspect_definition ::= name | expression | identifier + +1/3 + +2/3 + +3/3 + +4/3 + +13.1 Operational and Representation Aspects + +13 December 2012 300 + + Ada Reference Manual — 2012 Edition + +An aspect_mark identifies an aspect of the entity defined by the associated declaration (the associated +entity); the aspect denotes an object, a value, an expression, a subprogram, or some other kind of entity. If +the aspect_mark identifies: + +Name Resolution Rules + +• an aspect that denotes an object, the aspect_definition shall be a name. The expected type for + +the name is the type of the identified aspect of the associated entity; + +• an aspect that is a value or an expression, the aspect_definition shall be an expression. The +expected type for the expression is the type of the identified aspect of the associated entity; +• an aspect that denotes a subprogram, the aspect_definition shall be a name; the expected profile + +for the name is the profile required for the aspect of the associated entity; + +• an aspect that denotes some other kind of entity, the aspect_definition shall be a name, and the + +name shall resolve to denote an entity of the appropriate kind; + +• an aspect that is given by an identifier specific to the aspect, the aspect_definition shall be an + +identifier, and the identifier shall be one of the identifiers specific to the identified aspect. + +The usage names in an aspect_definition are not resolved at the point of the associated declaration, but +rather are resolved at the end of the immediately enclosing declaration list. + +If the associated declaration is for a subprogram or entry, the names of the formal parameters are directly +visible within the aspect_definition, as are certain attributes, as specified elsewhere in this International +Standard for the identified aspect. If the associated declaration is a type_declaration, within the +aspect_definition the names of any components are directly visible, and the name of the first subtype +denotes the current instance of the type (see 8.6). If the associated declaration is a subtype_declaration, +within the aspect_definition the name of the new subtype denotes the current instance of the subtype. + +Legality Rules + +If the first freezing point of the associated entity comes before the end of the immediately enclosing +declaration list, then each usage name in the aspect_definition shall resolve to the same entity at the first +freezing point as it does at the end of the immediately enclosing declaration list. + +At most one occurrence of each aspect_mark is allowed within a single aspect_specification. The aspect +identified by the aspect_mark shall be an aspect that can be specified for the associated entity (or view of +the entity defined by the associated declaration). + +The aspect_definition associated with a given aspect_mark may be omitted only when the aspect_mark +identifies an aspect of a boolean type, in which case it is equivalent to the aspect_definition being +specified as True. + +If the aspect_mark includes 'Class, then the associated entity shall be a tagged type or a primitive +subprogram of a tagged type. + +There are no language-defined aspects that may be specified on a renaming_declaration, a +generic_formal_parameter_declaration, a subunit, a package_body, a task_body, a protected_body, or +a body_stub other than a subprogram_body_stub. + +5/3 + +6/3 + +7/3 + +8/3 + +9/3 + +10/3 + +11/3 + +12/3 + +13/3 + +14/3 + +15/3 + +16/3 + +17/3 + +A language-defined aspect shall not be specified in an aspect_specification given on a subprogram_body +or subprogram_body_stub that is a completion of another declaration. + +18/3 + +Depending on which aspect is identified by the aspect_mark, an aspect_definition specifies: + +19/3 + +Static Semantics + +301 13 December 2012 + +Aspect Specifications 13.1.1 + + 20/3 + +21/3 + +22/3 + +23/3 + +24/3 + +25/3 + +26/3 + +27/3 + +28/3 + +29/3 + +30/3 + +31/3 + +32/3 + +33/3 + +34/3 + +35/3 + +Ada Reference Manual — 2012 Edition + +• a name that denotes a subprogram, object, or other kind of entity; +• an expression, which is either evaluated to produce a single value, or which (as in a + +precondition) is to be evaluated at particular points during later execution; or + +• an identifier specific to the aspect. + +The identified aspect of the associated entity, or in some cases, the view of the entity defined by the +declaration, is as specified by the aspect_definition (or by the default of True when boolean). Whether an +aspect_specification applies to an entity or only to the particular view of the entity defined by the +declaration is determined by the aspect_mark and the kind of entity. The following aspects are view +specific: + +• An aspect specified on an object_declaration; +• An aspect specified on a subprogram_declaration; +• An aspect specified on a renaming_declaration. + +All other aspect_specifications are associated with the entity, and apply to all views of the entity, unless +otherwise specified in this International Standard. + +If the aspect_mark includes 'Class, then: + +• +• + +if the associated entity is a tagged type, the specification applies to all descendants of the type; + +if the associated entity is a primitive subprogram of a tagged type T, the specification applies to +the corresponding primitive subprogram of all descendants of T. + +All specifiable operational and representation attributes may be specified with an aspect_specification +instead of an attribute_definition_clause (see 13.3). + +Any aspect specified by a representation pragma or library unit pragma that has a local_name as its single +argument may be specified by an aspect_specification, with the entity being the local_name. The +aspect_definition is expected to be of type Boolean. The expression shall be static. + +In addition, other operational and representation aspects not associated with specifiable attributes or +representation pragmas may be specified, as specified elsewhere in this International Standard. + +If an aspect of a derived type is inherited from an ancestor type and has the boolean value True, the +inherited value shall not be overridden to have the value False for the derived type, unless otherwise +specified in this International Standard. + +If a Legality Rule or Static Semantics rule only applies when a particular aspect has been specified, the +the aspect_specification or +aspect +attribute_definition_clause is visible (see 8.3) at the point of the application of the rule. + +specified only when + +to have been + +considered + +is + +36/3 + +Alternative legality and semantics rules may apply for particular aspects, as specified elsewhere in this +International Standard. + +Dynamic Semantics + +37/3 + +At the freezing point of the associated entity, the aspect_specification is elaborated. The elaboration of +the aspect_specification includes the evaluation of the name or expression, if any, unless the aspect itself +is an expression. If the corresponding aspect represents an expression (as in a precondition), the +elaboration has no effect; the expression is evaluated later at points within the execution as specified +elsewhere in this International Standard for the particular aspect. + +13.1.1 Aspect Specifications + +13 December 2012 302 + + Ada Reference Manual — 2012 Edition + +Implementations may support +implementation-defined aspects. The aspect_specification for an +implementation-defined aspect may use an implementation-defined syntax for the aspect_definition, and +may follow implementation-defined legality and semantics rules. + +38/3 + +Implementation Permissions + +13.2 Packed Types + +The Pack aspect having the value True specifies that storage minimization should be the main criterion +when selecting the representation of a composite type. + +1/3 + +Paragraphs 2 through 4 were moved to Annex J, “Obsolescent Features”. + +Static Semantics + +For a full type declaration of a composite type, the following language-defined representation aspect may +be specified: + +Pack + +The type of aspect Pack is Boolean. When aspect Pack is True for a type, the type (or the +extension part) is said to be packed. For a type extension, the parent part is packed as for +the parent type, and specifying Pack causes packing only of the extension part. + +5/3 + +5.1/3 + +If directly specified, the aspect_definition shall be a static expression. If not specified +(including by inheritance), the aspect is False. + +5.2/3 + +Implementation Advice + +If a type is packed, then the implementation should try to minimize storage allocated to objects of the type, +possibly at the expense of speed of accessing components, subject to reasonable complexity in addressing +calculations. + +6 + +If a packed type has a component that is not of a by-reference type and has no aliased part, then such a +component need not be aligned according to the Alignment of its subtype; in particular it need not be +allocated on a storage element boundary. + +6.1/2 + +The recommended level of support for the Pack aspect is: + +• For a packed record type, the components should be packed as tightly as possible subject to the +Sizes of the component subtypes, and subject to any record_representation_clause that applies +to the type; the implementation may, but need not, reorder components or cross aligned word +boundaries to improve the packing. A component whose Size is greater than the word size may +be allocated an integral number of words. + +• For a packed array type, if the Size of the component subtype is less than or equal to the word +size, Component_Size should be less than or equal to the Size of the component subtype, +rounded up to the nearest factor of the word size. + +7/3 + +8 + +9/3 + +303 13 December 2012 + +Aspect Specifications 13.1.1 + + + Ada Reference Manual — 2012 Edition + +13.3 Operational and Representation Attributes + +1/1 + +The values of certain implementation-dependent characteristics can be obtained by interrogating +appropriate operational or representation attributes. Some of these attributes are specifiable via an +attribute_definition_clause. + +2 + +3 + +4 + +5/3 + +6 + +7/2 + +8 + +attribute_definition_clause ::= + for local_name'attribute_designator use expression; + | for local_name'attribute_designator use name; + +Syntax + +Name Resolution Rules + +For an attribute_definition_clause that specifies an attribute that denotes a value, the form with an +expression shall be used. Otherwise, the form with a name shall be used. + +For an attribute_definition_clause that specifies an attribute that denotes a value or an object, the expected +type for the expression or name is that of the attribute. For an attribute_definition_clause that specifies an +attribute that denotes a subprogram, the expected profile for the name is the profile required for the +attribute. For an attribute_definition_clause that specifies an attribute that denotes some other kind of +entity, the name shall resolve to denote an entity of the appropriate kind. + +Legality Rules + +An attribute_designator is allowed in an attribute_definition_clause only if this International Standard +explicitly allows it, or for an implementation-defined attribute if the implementation allows it. Each +specifiable attribute constitutes an operational aspect or aspect of representation; the name of the aspect is +that of the attribute. + +For an attribute_definition_clause that specifies an attribute that denotes a subprogram, the profile shall be +mode conformant with the one required for the attribute, and the convention shall be Ada. Additional +requirements are defined for particular attributes. + +Static Semantics + +A Size clause is an attribute_definition_clause whose attribute_designator is Size. Similar definitions +apply to the other specifiable attributes. + +A storage element is an addressable element of storage in the machine. A word is the largest amount of +storage that can be conveniently and efficiently manipulated by the hardware, given the implementation's +run-time model. A word consists of an integral number of storage elements. + +8.1/3 + +A machine scalar is an amount of storage that can be conveniently and efficiently loaded, stored, or +operated upon by the hardware. Machine scalars consist of an integral number of storage elements. The set +of machine scalars is implementation defined, but includes at least the storage element and the word. +Machine scalars are used to interpret component_clauses when the nondefault bit ordering applies. + +9/3 + +The following representation attributes are defined: Address, Alignment, Size, Storage_Size, +Component_Size, Has_Same_Storage, and Overlaps_Storage. + +10/1 + +For a prefix X that denotes an object, program unit, or label: + +11 + +X'Address + +Denotes the address of the first of the storage elements allocated to X. For a program unit or +label, this value refers to the machine code associated with the corresponding body or +statement. The value of this attribute is of type System.Address. + +13.3 Operational and Representation Attributes + +13 December 2012 304 + + Ada Reference Manual — 2012 Edition + +The prefix of X'Address shall not statically denote a subprogram that has convention +Intrinsic. X'Address raises Program_Error if X denotes a subprogram that has convention +Intrinsic. + +11.1/3 + +Address may be specified for stand-alone objects and for program units via an +attribute_definition_clause. + +12 + +If an Address is specified, it is the programmer's responsibility to ensure that the address is valid and +appropriate for the entity and its use; otherwise, program execution is erroneous. + +13/3 + +Erroneous Execution + +Implementation Advice + +For an array X, X'Address should point at the first component of the array, and not at the array bounds. + +The recommended level of support for the Address attribute is: + +• X'Address should produce a useful result if X is an object that is aliased or of a by-reference + +type, or is an entity whose Address has been specified. + +• An implementation should support Address clauses for imported subprograms. +• This paragraph was deleted. +• If the Address of an object is specified, or it is imported or exported, then the implementation + +should not perform optimizations based on assumptions of no aliases. + +NOTES +2 The specification of a link name with the Link_Name aspect (see B.1) for a subprogram or object is an alternative to +explicit specification of its link-time address, allowing a link-time directive to place the subprogram or object within +memory. + +3 The rules for the Size attribute imply, for an aliased object X, that if X'Size = Storage_Unit, then X'Address points at a +storage element containing all of the bits of X, and only the bits of X. + +For a prefix X that denotes an object: + +Static Semantics + +X'Alignment The value of this attribute is of type universal_integer, and nonnegative; zero means that +the object is not necessarily aligned on a storage element boundary. If X'Alignment is not +zero, then X is aligned on a storage unit boundary and X'Address is an integral multiple of +X'Alignment (that is, the Address modulo the Alignment is zero). + +This paragraph was deleted. + +Alignment may be specified for stand-alone objects via an attribute_definition_clause; the +expression of such a clause shall be static, and its value nonnegative. + +This paragraph was deleted. + +For every subtype S: + +S'Alignment The value of this attribute is of type universal_integer, and nonnegative. + +For an object X of subtype S, if S'Alignment is not zero, then X'Alignment is a nonzero +integral multiple of S'Alignment unless specified otherwise by a representation item. + +Alignment may be specified for first subtypes via an attribute_definition_clause; the +expression of such a clause shall be static, and its value nonnegative. + +14 + +15 + +16 + +17 + +18/2 + +19 + +20 + +21 + +22/2 + +23/2 + +24/2 + +25/2 + +26/2 + +26.1/2 + +26.2/2 + +26.3/2 + +26.4/2 + +Program execution is erroneous if an Address clause is given that conflicts with the Alignment. + +27 + +Erroneous Execution + +305 13 December 2012 + +Operational and Representation Attributes 13.3 + + + + + + + + + Ada Reference Manual — 2012 Edition + +28/2 + +For an object that is not allocated under control of the implementation, execution is erroneous if the object +is not aligned according to its Alignment. + +28.1/3 + +For any tagged specific subtype S, S'Class'Alignment should equal S'Alignment. + +29 + +The recommended level of support for the Alignment attribute for subtypes is: + +Implementation Advice + +30/2 + +31/2 + +32/2 + +• An implementation should support an Alignment clause for a discrete type, fixed point type, +record type, or array type, specifying an Alignment value that is zero or a power of two, subject +to the following: + +• An implementation need not support an Alignment clause for a signed integer type specifying an +Alignment greater than the largest Alignment value that is ever chosen by default by the +implementation for any signed integer type. A corresponding limitation may be imposed for +modular integer types, fixed point types, enumeration types, record types, and array types. + +• An implementation need not support a nonconfirming Alignment clause which could enable the +creation of an object of an elementary type which cannot be easily loaded and stored by +available machine instructions. + +32.1/2 + +• An implementation need not support an Alignment specified for a derived tagged type which is +not a multiple of the Alignment of the parent type. An implementation need not support a +nonconfirming Alignment specified for a derived untagged by-reference type. + +33 + +The recommended level of support for the Alignment attribute for objects is: + +34/2 + +35 + +• This paragraph was deleted. +• For stand-alone library-level objects of statically constrained subtypes, the implementation +should support all Alignments supported by the target linker. For example, page alignment is +likely to be supported for such objects, but not for subtypes. + +35.1/2 + +• For other objects, an implementation should at least support the alignments supported for their + +subtype, subject to the following: + +35.2/2 + +36 + +37/2 + +38/3 + +• An implementation need not support Alignments specified for objects of a by-reference type or +for objects of types containing aliased subcomponents if the specified Alignment is not a +multiple of the Alignment of the subtype of the object. + +NOTES +4 Alignment is a subtype-specific attribute. + +This paragraph was deleted. + +5 A component_clause, Component_Size clause, or specifying the Pack aspect as True can override a specified +Alignment. + +39/1 + +For a prefix X that denotes an object: + +Static Semantics + +40 + +X'Size + +Denotes the size in bits of the representation of the object. The value of this attribute is of +the type universal_integer. + +41 + +Size may be specified for stand-alone objects via an attribute_definition_clause; the +expression of such a clause shall be static and its value nonnegative. + +41.1/2 + +The size of an array object should not include its bounds. + +Implementation Advice + +13.3 Operational and Representation Attributes + +13 December 2012 306 + + + The recommended level of support for the Size attribute of objects is the same as for subtypes (see below), +except that only a confirming Size clause need be supported for an aliased elementary object. + +Ada Reference Manual — 2012 Edition + +• This paragraph was deleted. + +For every subtype S: + +Static Semantics + +S'Size + +If S is definite, denotes the size (in bits) that the implementation would choose for the +following objects of subtype S: + +• A record component of subtype S when the record type is packed. +• The formal parameter of an instance of Unchecked_Conversion that converts + +from subtype S to some other subtype. + +If S is indefinite, the meaning is implementation defined. The value of this attribute is of +the type universal_integer. The Size of an object is at least as large as that of its subtype, +unless the object's Size is determined by a Size clause, a component_clause, or a +Component_Size clause. Size may be specified for first subtypes via an attribute_- +definition_clause; the expression of such a clause shall be static and its value nonnegative. + +In an implementation, Boolean'Size shall be 1. + +Implementation Requirements + +Implementation Advice + +42/2 + +43/2 + +44 + +45 + +46 + +47 + +48 + +49 + +If the Size of a subtype allows for efficient independent addressability (see 9.10) on the target architecture, +then the Size of the following objects of the subtype should equal the Size of the subtype: + +50/2 + +• Aliased objects (including components). +• Unaliased components, unless the Size of the component is determined by a component_clause + +or Component_Size clause. + +A Size clause on a composite subtype should not affect the internal layout of components. + +The recommended level of support for the Size attribute of subtypes is: + +• The Size (if not specified) of a static discrete or fixed point subtype should be the number of bits +needed to represent each value belonging to the subtype using an unbiased representation, +leaving space for a sign bit only if the subtype contains negative values. If such a subtype is a +first subtype, then an implementation should support a specified Size for it that reflects this +representation. + +51 + +52 + +53 + +54 + +55 + +• For a subtype implemented with levels of indirection, the Size should include the size of the + +56 + +pointers, but not the size of what they point at. + +• An implementation should support a Size clause for a discrete type, fixed point type, record + +type, or array type, subject to the following: + +• An implementation need not support a Size clause for a signed integer type specifying a +Size greater than that of the largest signed integer type supported by the implementation in +the absence of a size clause (that is, when the size is chosen by default). A corresponding +limitation may be imposed for modular integer types, fixed point types, enumeration types, +record types, and array types. + +56.1/2 + +56.2/2 + +• A nonconfirming size clause for the first subtype of a derived untagged by-reference type + +56.3/2 + +need not be supported. + +307 13 December 2012 + +Operational and Representation Attributes 13.3 + + + 57 + +58/3 + +59/1 + +60/3 + +Ada Reference Manual — 2012 Edition + +NOTES +6 Size is a subtype-specific attribute. + +7 A component_clause or Component_Size clause can override a specified Size. Aspect Pack cannot. + +For a prefix T that denotes a task object (after any implicit dereference): + +Static Semantics + +T'Storage_Size + +Denotes the number of storage elements reserved for the task. The value of this attribute is +of the type universal_integer. The Storage_Size includes the size of the task's stack, if any. +The language does not specify whether or not it includes other storage associated with the +task (such as the “task control block” used by some implementations.) If the aspect +Storage_Size is specified for the type of the object, the value of the Storage_Size attribute +is at least the value determined by the aspect. + +61/3 + +Aspect Storage_Size specifies the amount of storage to be reserved for the execution of a task. + +Paragraphs 62 through 65 were moved to Annex J, “Obsolescent Features”. + +65.1/3 + +For a task type (including the anonymous type of a single_task_declaration), the following language- +defined representation aspect may be specified: + +65.2/3 + +Storage_Size The Storage_Size aspect is an expression, which shall be of any integer type. + +Static Semantics + +65.3/3 + +The Storage_Size aspect shall not be specified for a task interface type. + +Legality Rules + +Dynamic Semantics + +66/3 + +When a task object is created, the expression (if any) associated with the Storage_Size aspect of its type is +evaluated; the Storage_Size attribute of the newly created task object is at least the value of the +expression. + +67 + +At the point of task object creation, or upon task activation, Storage_Error is raised if there is insufficient +free storage to accommodate the requested Storage_Size. + +68/1 + +For a prefix X that denotes an array subtype or array object (after any implicit dereference): + +Static Semantics + +69 + +X'Component_Size + +Denotes the size in bits of components of the type of X. The value of this attribute is of type +universal_integer. + +Component_Size may be specified for array types via an attribute_definition_clause; the +expression of such a clause shall be static, and its value nonnegative. + +Implementation Advice + +The recommended level of support for the Component_Size attribute is: + +• An implementation need not support specified Component_Sizes that are less than the Size of + +the component subtype. + +• An implementation should support specified Component_Sizes that are factors and multiples of +the word size. For such Component_Sizes, the array should contain no gaps between +components. For other Component_Sizes (if supported), the array should contain no gaps + +70 + +71 + +72 + +73/3 + +13.3 Operational and Representation Attributes + +13 December 2012 308 + + + + + between components when Pack is also specified; the implementation should forbid this +combination in cases where it cannot support a no-gaps representation. + +Ada Reference Manual — 2012 Edition + +For a prefix X that denotes an object: + +X'Has_Same_Storage + +Static Semantics + +X'Has_Same_Storage denotes a function with the following specification: + +function X'Has_Same_Storage (Arg : any_type) + return Boolean + +The actual parameter shall be a name that denotes an object. The object denoted by the +actual parameter can be of any type. This function evaluates the names of the objects +involved and returns True if the representation of the object denoted by the actual +parameter occupies exactly the same bits as the representation of the object denoted by X; +otherwise, it returns False. + +For a prefix X that denotes an object: + +X'Overlaps_Storage + +X'Overlaps_Storage denotes a function with the following specification: + +function X'Overlaps_Storage (Arg : any_type) + return Boolean + +The actual parameter shall be a name that denotes an object. The object denoted by the +actual parameter can be of any type. This function evaluates the names of the objects +involved and returns True if the representation of the object denoted by the actual +parameter shares at least one bit with the representation of the object denoted by X; +otherwise, it returns False. + +NOTES +8 X'Has_Same_Storage(Y) implies X'Overlaps_Storage(Y). + +9 X'Has_Same_Storage(Y) and X'Overlaps_Storage(Y) are not considered to be reads of X and Y. + +The following type-related operational attribute is defined: External_Tag. + +For every subtype S of a tagged type T (specific or class-wide): + +Static Semantics + +S'External_Tag + +73.1/3 + +73.2/3 + +73.3/3 + +73.4/3 + +73.5/3 + +73.6/3 + +73.7/3 + +73.8/3 + +73.9/3 + +73.10/3 + +73.11/3 + +74/1 + +75/3 + +S'External_Tag denotes an external string representation for S'Tag; it is of the predefined +type String. External_Tag may be specified for a specific tagged type via an +attribute_definition_clause; the expression of such a clause shall be static. The default +external tag representation is implementation defined. See 13.13.2. The value of +External_Tag is never inherited; the default value is always used unless a new value is +directly specified for a type. + +If a user-specified external tag S'External_Tag is the same as T'External_Tag for some other tagged type +declared by a different declaration in the partition, Program_Error is raised by the elaboration of the +attribute_definition_clause. + +75.1/3 + +Dynamic Semantics + +In an implementation, the default external tag for each specific tagged type declared in a partition shall be +distinct, so long as the type is declared outside an instance of a generic body. If the compilation unit in +which a given tagged type is declared, and all compilation units on which it semantically depends, are the + +76 + +Implementation Requirements + +309 13 December 2012 + +Operational and Representation Attributes 13.3 + + + + + + + Ada Reference Manual — 2012 Edition + +same in two different partitions, then the external tag for the type shall be the same in the two partitions. +What it means for a compilation unit to be the same in two different partitions is implementation defined. +At a minimum, if the compilation unit is not recompiled between building the two different partitions that +include it, the compilation unit is considered the same in the two partitions. + +76.1/3 + +If a user-specified external tag S'External_Tag is the same as T'External_Tag for some other tagged type +declared by a different declaration in the partition, the partition may be rejected. + +Implementation Permissions + +77/2 + +78 + +79 + +80 + +81 + +82 + +83 + +84/2 + +85 + +1 + +2 + +3 + +4 + +NOTES +10 The following language-defined attributes are specifiable, at least for some of the kinds of entities to which they apply: +Address, Alignment, Bit_Order, Component_Size, External_Tag, Input, Machine_Radix, Output, Read, Size, Small, +Storage_Pool, Storage_Size, Stream_Size, and Write. + +11 It follows from the general rules in 13.1 that if one writes “for X'Size use Y;” then the X'Size attribute_reference will +return Y (assuming the implementation allows the Size clause). The same is true for all of the specifiable attributes except +Storage_Size. + +Examples of attribute definition clauses: + +Examples + +Byte : constant := 8; +Page : constant := 2**12; +type Medium is range 0 .. 65_000; +for Medium'Size use 2*Byte; +for Medium'Alignment use 2; +Device_Register : Medium; +for Device_Register'Size use Medium'Size; +for Device_Register'Address use +System.Storage_Elements.To_Address(16#FFFF_0020#); +type Short is delta 0.01 range -100.0 .. 100.0; +for Short'Size use 15; +for Car_Name'Storage_Size use -- specify access type's storage pool size + 2000*((Car'Size/System.Storage_Unit) +1); -- approximately 2000 cars +function My_Input(Stream : not null access +Ada.Streams.Root_Stream_Type'Class) + return T; +for T'Input use My_Input; -- see 13.13.2 + +NOTES +12 Notes on the examples: In the Size clause for Short, fifteen bits is the minimum necessary, since the type definition +requires Short'Small <= 2**(–7). + +13.4 Enumeration Representation Clauses + +An enumeration_representation_clause specifies the internal codes for enumeration literals. + +enumeration_representation_clause ::= + for first_subtype_local_name use enumeration_aggregate; + +enumeration_aggregate ::= array_aggregate + +Syntax + +Name Resolution Rules + +The enumeration_aggregate shall be written as a one-dimensional array_aggregate, for which the index +subtype is the unconstrained subtype of the enumeration type, and each component expression is expected +to be of any integer type. + +13.3 Operational and Representation Attributes + +13 December 2012 310 + + Ada Reference Manual — 2012 Edition + +Legality Rules + +The first_subtype_local_name of an enumeration_representation_clause shall denote an enumeration +subtype. + +Each component of the array_aggregate shall be given by an expression rather than a <>. The +expressions given in the array_aggregate shall be static, and shall specify distinct integer codes for each +value of the enumeration type; the associated integer codes shall satisfy the predefined ordering relation of +the type. + +An enumeration_representation_clause specifies the coding aspect of representation. The coding +consists of the internal code for each enumeration literal, that is, the integral value used internally to +represent each literal. + +Static Semantics + +For nonboolean enumeration types, if the coding is not specified for the type, then for each value of the +type, the internal code shall be equal to its position number. + +Implementation Requirements + +The recommended level of support for enumeration_representation_clauses is: + +Implementation Advice + +• An + +implementation + +should + +System.Min_Int..System.Max_Int. An +representation_clauses for boolean types. + +support at + +least + +range +internal codes +implementation need not support enumeration_- + +the + +the + +in + +NOTES +13 Unchecked_Conversion may be used to query the internal codes used for an enumeration type. The attributes of the +type, such as Succ, Pred, and Pos, are unaffected by the enumeration_representation_clause. For example, Pos always +in an +returns +enumeration_representation_clause. + +that might have been specified + +the position number, not + +integer code + +internal + +the + +Example of an enumeration representation clause: + +Examples + +type Mix_Code is (ADD, SUB, MUL, LDA, STA, STZ); +for Mix_Code use + (ADD => 1, SUB => 2, MUL => 3, LDA => 8, STA => 24, STZ =>33); + +13.5 Record Layout + +The (record) layout aspect of representation consists of the storage places for some or all components, that +is, storage place attributes of the components. The layout can be specified with a record_representation_- +clause. + +311 13 December 2012 + +Enumeration Representation Clauses 13.4 + +5 + +6/2 + +7 + +8 + +9 + +10 + +11/3 + +12 + +13 + +14 + +1 + + Ada Reference Manual — 2012 Edition + +13.5.1 Record Representation Clauses + +A record_representation_clause specifies the storage representation of records and record extensions, +that is, the order, position, and size of components (including discriminants, if any). + +Syntax + +record_representation_clause ::= + for first_subtype_local_name use + record [mod_clause] + {component_clause} + end record; + +component_clause ::= + component_local_name at position range first_bit .. last_bit; + +position ::= static_expression + +first_bit ::= static_simple_expression + +last_bit ::= static_simple_expression + +Each position, first_bit, and last_bit is expected to be of any integer type. + +Name Resolution Rules + +Legality Rules + +The first_subtype_local_name of a record_representation_clause shall denote a specific record or record +extension subtype. + +If the component_local_name is a direct_name, the local_name shall denote a component of the type. For +a record extension, the component shall not be inherited, and shall not be a discriminant that corresponds +to a discriminant of the parent type. If the component_local_name has an attribute_designator, the +direct_name of the local_name shall denote either the declaration of the type or a component of the type, +and the attribute_designator shall denote an implementation-defined implicit component of the type. + +1 + +2 + +3 + +4 + +5 + +6 + +7 + +8/2 + +9 + +10 + +The position, first_bit, and last_bit shall be static expressions. The value of position and first_bit shall be +nonnegative. The value of last_bit shall be no less than first_bit – 1. + +10.1/2 + +If the nondefault bit ordering applies to the type, then either: + +10.2/2 + +10.3/2 + +11 + +• +• + +the value of last_bit shall be less than the size of the largest machine scalar; or + +the value of first_bit shall be zero and the value of last_bit + 1 shall be a multiple of +System.Storage_Unit. + +At most one component_clause is allowed for each component of the type, including for each +discriminant (component_clauses may be given for some, all, or none of the components). Storage places +within a component_list shall not overlap, unless they are for components in distinct variants of the same +variant_part. + +12 + +A name that denotes a component of a type is not allowed within a record_representation_clause for the +type, except as the component_local_name of a component_clause. + +13/2 + +A record_representation_clause (without the mod_clause) specifies the layout. + +Static Semantics + +13.5.1 Record Representation Clauses + +13 December 2012 312 + + Ada Reference Manual — 2012 Edition + +If the default bit ordering applies to the type, the position, +component_clause directly specify the position and size of the corresponding component. + +first_bit, and + +last_bit of each + +If the nondefault bit ordering applies to the type, then the layout is determined as follows: + +• + +the component_clauses for which the value of last_bit is greater than or equal to the size of the +largest machine scalar directly specify the position and size of the corresponding component; +• for other component_clauses, all of the components having the same value of position are +considered to be part of a single machine scalar, located at that position; this machine scalar has +a size which is the smallest machine scalar size larger than the largest last_bit for all +component_clauses at that position; the first_bit and last_bit of each component_clause are +then interpreted as bit offsets in this machine scalar. + +A record_representation_clause for a record extension does not override the layout of the parent part; if +the layout was specified for the parent type, it is inherited by the record extension. + +Implementation Permissions + +An implementation may generate implementation-defined components (for example, one containing the +offset of another component). An implementation may generate names that denote such implementation- +defined components; such names shall be implementation-defined attribute_references. An implemen- +tation may allow such implementation-defined names to be used in record_representation_clauses. An +implementation can restrict such component_clauses in any manner it sees fit. + +If a record_representation_clause is given for an untagged derived type, the storage place attributes for +all of the components of the derived type may differ from those of the corresponding components of the +parent type, even for components whose storage place is not specified explicitly in the record_- +representation_clause. + +Implementation Advice + +The recommended level of support for record_representation_clauses is: + +• An implementation should support machine scalars that correspond to all of the integer, floating + +point, and address formats supported by the machine. + +• An implementation should support storage places that can be extracted with a load, mask, shift +sequence of machine code, and set with a load, shift, mask, store sequence, given the available +machine instructions and run-time model. + +• A storage place should be supported if its size is equal to the Size of the component subtype, and + +it starts and ends on a boundary that obeys the Alignment of the component subtype. + +13.1/2 + +13.2/3 + +13.3/2 + +13.4/2 + +14 + +15 + +16 + +17 + +17.1/2 + +18 + +19 + +• For a component with a subtype whose Size is less than the word size, any storage place that + +20/2 + +does not cross an aligned word boundary should be supported. + +• An implementation may reserve a storage place for the tag field of a tagged type, and disallow + +other components from overlapping that place. + +• An implementation need not support a component_clause for a component of an extension part +if the storage place is not after the storage places of all components of the parent type, whether +or not those storage places had been specified. + +NOTES +14 If no component_clause is given for a component, then the choice of the storage place for the component is left to the +implementation. If component_clauses are given for all components, the record_representation_clause completely +specifies the representation of the type and will be obeyed exactly by the implementation. + +21 + +22 + +23 + +313 13 December 2012 + +Record Representation Clauses 13.5.1 + + Ada Reference Manual — 2012 Edition + +Example of specifying the layout of a record type: + +Examples + +Word : constant := 4; -- storage element is byte, 4 bytes per word +type State is (A,M,W,P); +type Mode is (Fix, Dec, Exp, Signif); +type Byte_Mask is array (0..7) of Boolean; +type State_Mask is array (State) of Boolean; +type Mode_Mask is array (Mode) of Boolean; +type Program_Status_Word is + record + System_Mask : Byte_Mask; + Protection_Key : Integer range 0 .. 3; + Machine_State : State_Mask; + Interrupt_Cause : Interruption_Code; + Ilc : Integer range 0 .. 3; + Cc : Integer range 0 .. 3; + Program_Mask : Mode_Mask; + Inst_Address : Address; +end record; +for Program_Status_Word use + record + System_Mask at 0*Word range 0 .. 7; + Protection_Key at 0*Word range 10 .. 11; -- bits 8,9 unused + Machine_State at 0*Word range 12 .. 15; + Interrupt_Cause at 0*Word range 16 .. 31; + Ilc at 1*Word range 0 .. 1; -- second word + Cc at 1*Word range 2 .. 3; + Program_Mask at 1*Word range 4 .. 7; + Inst_Address at 1*Word range 8 .. 31; + end record; +for Program_Status_Word'Size use 8*System.Storage_Unit; +for Program_Status_Word'Alignment use 8; + +NOTES +15 Note on the example: The record_representation_clause defines the record layout. The Size clause guarantees that (at +least) eight storage elements are used for objects of the type. The Alignment clause guarantees that aliased, imported, or +exported objects of the type will have addresses divisible by eight. + +13.5.2 Storage Place Attributes + +Static Semantics + +For a component C of a composite, non-array object R, the storage place attributes are defined: + +R.C'Position + +If the nondefault bit ordering applies to the composite type, and if a component_clause +specifies the placement of C, denotes the value given for the position of the +component_clause; otherwise, denotes the same value as R.C'Address – R'Address. The +value of this attribute is of the type universal_integer. + +24 + +25 + +26 + +27 + +28 + +29 + +30 + +31 + +1 + +2/2 + +3/2 + +R.C'First_Bit + +If the nondefault bit ordering applies to the composite type, and if a component_clause +specifies the placement of C, denotes the value given for the first_bit of the +component_clause; otherwise, denotes the offset, from the start of the first of the storage +elements occupied by C, of the first bit occupied by C. This offset is measured in bits. The +first bit of a storage element is numbered zero. The value of this attribute is of the type +universal_integer. + +13.5.1 Record Representation Clauses + +13 December 2012 314 + + + Ada Reference Manual — 2012 Edition + +R.C'Last_Bit + +If the nondefault bit ordering applies to the composite type, and if a component_clause +specifies the placement of C, denotes the value given for the +last_bit of the +component_clause; otherwise, denotes the offset, from the start of the first of the storage +elements occupied by C, of the last bit occupied by C. This offset is measured in bits. The +value of this attribute is of the type universal_integer. + +Implementation Advice + +If a component is represented using some form of pointer (such as an offset) to the actual data of the +component, and this data is contiguous with the rest of the object, then the storage place attributes should +reflect the place of the actual data, not the pointer. If a component is allocated discontiguously from the +rest of the object, then a warning should be generated upon reference to one of its storage place attributes. + +13.5.3 Bit Ordering + +The Bit_Order attribute specifies the interpretation of the storage place attributes. + +Static Semantics + +A bit ordering is a method of interpreting the meaning of the storage place attributes. High_Order_First +(known in the vernacular as “big endian”) means that the first bit of a storage element (bit 0) is the most +significant bit (interpreting the sequence of bits that represent a component as an unsigned integer value). +Low_Order_First (known in the vernacular as “little endian”) means the opposite: the first bit is the least +significant. + +For every specific record subtype S, the following attribute is defined: + +S'Bit_Order Denotes the bit ordering for the type of S. The value of this attribute is of type +System.Bit_Order. Bit_Order may be specified for specific record types via an +attribute_definition_clause; the expression of such a clause shall be static. + +If Word_Size = Storage_Unit, the default bit ordering is implementation defined. If Word_Size > +Storage_Unit, the default bit ordering is the same as the ordering of storage elements in a word, when +interpreted as an integer. + +The storage place attributes of a component of a type are interpreted according to the bit ordering of the +type. + +Implementation Advice + +The recommended level of support for the nondefault bit ordering is: + +• The implementation should support the nondefault bit ordering in addition to the default bit + +ordering. + +NOTES +16 Bit_Order clauses make it possible to write record_representation_clauses that can be ported between machines +having different bit ordering. They do not guarantee transparent exchange of data between such machines. + +4/2 + +5 + +1 + +2 + +3 + +4 + +5 + +6 + +7 + +8/2 + +9/2 + +315 13 December 2012 + +Storage Place Attributes 13.5.2 + + + Ada Reference Manual — 2012 Edition + +13.6 Change of Representation + +A type_conversion (see 4.6) can be used to convert between two different representations of the same +array or record. To convert an array from one representation to another, two array types need to be +declared with matching component subtypes, and convertible index types. If one type has Pack specified +and the other does not, then explicit conversion can be used to pack or unpack an array. + +To convert a record from one representation to another, two record types with a common ancestor type +need to be declared, with no inherited subprograms. Distinct representations can then be specified for the +record types, and explicit conversion between the types can be used to effect a change in representation. + +Example of change of representation: + +Examples + +-- Packed_Descriptor and Descriptor are two different types +-- with identical characteristics, apart from their +-- representation +type Descriptor is + record + -- components of a descriptor + end record; +type Packed_Descriptor is new Descriptor; +for Packed_Descriptor use + record + -- component clauses for some or for all components + end record; +-- Change of representation can now be accomplished by explicit type conversions: +D : Descriptor; +P : Packed_Descriptor; +P := Packed_Descriptor(D); -- pack D +D := Descriptor(P); -- unpack P + +1/3 + +2 + +3 + +4 + +5 + +6 + +7 + +8 + +9 + +10 + +13.6 Change of Representation + +13 December 2012 316 + + Ada Reference Manual — 2012 Edition + +13.7 The Package System + +For each implementation there is a library package called System which includes the definitions of certain +configuration-dependent characteristics. + +1 + +The following language-defined library package exists: + +Static Semantics + +package System is + pragma Pure(System); + type Name is implementation-defined-enumeration-type; + System_Name : constant Name := implementation-defined; + -- System-Dependent Named Numbers: + Min_Int : constant := root_integer'First; + Max_Int : constant := root_integer'Last; + Max_Binary_Modulus : constant := implementation-defined; + Max_Nonbinary_Modulus : constant := implementation-defined; + Max_Base_Digits : constant := root_real'Digits; + Max_Digits : constant := implementation-defined; + Max_Mantissa : constant := implementation-defined; + Fine_Delta : constant := implementation-defined; + Tick : constant := implementation-defined; + -- Storage-related Declarations: + type Address is implementation-defined; + Null_Address : constant Address; + Storage_Unit : constant := implementation-defined; + Word_Size : constant := implementation-defined * Storage_Unit; + Memory_Size : constant := implementation-defined; + -- Address Comparison: + function "<" (Left, Right : Address) return Boolean + with Convention => Intrinsic; + function "<="(Left, Right : Address) return Boolean + with Convention => Intrinsic; + function ">" (Left, Right : Address) return Boolean + with Convention => Intrinsic; + function ">="(Left, Right : Address) return Boolean + with Convention => Intrinsic; + function "=" (Left, Right : Address) return Boolean + with Convention => Intrinsic; +-- function "/=" (Left, Right : Address) return Boolean; + -- "/=" is implicitly defined + -- Other System-Dependent Declarations: + type Bit_Order is (High_Order_First, Low_Order_First); + Default_Bit_Order : constant Bit_Order := implementation-defined; + -- Priority-related declarations (see D.1): + subtype Any_Priority is Integer range implementation-defined; + subtype Priority is Any_Priority range Any_Priority'First .. + implementation-defined; + subtype Interrupt_Priority is Any_Priority range Priority'Last+1 .. + Any_Priority'Last; + Default_Priority : constant Priority := + (Priority'First + Priority'Last)/2; +private + ... -- not specified by the language +end System; + +2 + +3/2 + +4 + +5 + +6 + +7 + +8 + +9 + +10 + +11 + +12 + +13 + +14/3 + +15/2 + +16 + +17 + +18 + +317 13 December 2012 + +The Package System 13.7 + + Ada Reference Manual — 2012 Edition + +19 + +20 + +21 + +22 + +Name is an enumeration subtype. Values of type Name are the names of alternative machine configura- +tions handled by the implementation. System_Name represents the current machine configuration. + +The named numbers Fine_Delta and Tick are of the type universal_real; the others are of the type +universal_integer. + +The meanings of the named numbers are: + +Min_Int + +The smallest (most negative) value allowed for the expressions of a signed_integer_type_- +definition. + +23 + +Max_Int + +The largest (most positive) value allowed for the expressions of a signed_integer_type_- +definition. + +24 + +Max_Binary_Modulus + +A power of two such that it, and all lesser positive powers of two, are allowed as the +modulus of a modular_type_definition. + +25 + +Max_Nonbinary_Modulus + +A value such that it, and all lesser positive integers, are allowed as the modulus of a +modular_type_definition. + +26 + +Max_Base_Digits + +The largest value allowed for the requested decimal precision in a floating_point_definition. + +27 + +Max_Digits The largest value allowed for the requested decimal precision in a floating_point_definition +to +real_range_specification. Max_Digits + +than or equal + +less + +is + +that has no +Max_Base_Digits. + +28 + +Max_Mantissa + +The largest possible number of binary digits in the mantissa of machine numbers of a user- +defined ordinary fixed point type. (The mantissa is defined in Annex G.) + +29 + +Fine_Delta The smallest delta allowed in an ordinary_fixed_point_definition that has the real_range_- + +specification range –1.0 .. 1.0. + +30 + +Tick + +A period in seconds approximating the real time interval during which the value of +Calendar.Clock remains constant. + +31 + +Storage_Unit + +32 + +33 + +34/2 + +The number of bits per storage element. + +Word_Size The number of bits per word. + +Memory_Size An implementation-defined value that is intended to reflect the memory size of the + +configuration in storage elements. + +Address is a definite, nonlimited type with preelaborable initialization (see 10.2.1). Address represents +machine addresses capable of addressing individual storage elements. Null_Address is an address that is +distinct from the address of any object or program unit. + +35/2 + +Default_Bit_Order shall be a static constant. See 13.5.3 for an explanation of Bit_Order and +Default_Bit_Order. + +36/2 + +An implementation may add additional implementation-defined declarations to package System and its +children. However, it is usually better for the implementation to provide additional functionality via +implementation-defined children of System. + +Implementation Permissions + +13.7 The Package System + +13 December 2012 318 + + + + + + + Ada Reference Manual — 2012 Edition + +Address should be a private type. + +Implementation Advice + +NOTES +17 There are also some language-defined child packages of System defined elsewhere. + +13.7.1 The Package System.Storage_Elements + +Static Semantics + +The following language-defined library package exists: +package System.Storage_Elements is + pragma Pure(Storage_Elements); + type Storage_Offset is range implementation-defined; + subtype Storage_Count is Storage_Offset range 0..Storage_Offset'Last; + type Storage_Element is mod implementation-defined; + for Storage_Element'Size use Storage_Unit; + type Storage_Array is array + (Storage_Offset range <>) of aliased Storage_Element; + for Storage_Array'Component_Size use Storage_Unit; + -- Address Arithmetic: + function "+"(Left : Address; Right : Storage_Offset) return Address + with Convention => Intrinsic; + function "+"(Left : Storage_Offset; Right : Address) return Address + with Convention => Intrinsic; + function "-"(Left : Address; Right : Storage_Offset) return Address + with Convention => Intrinsic; + function "-"(Left, Right : Address) return Storage_Offset + with Convention => Intrinsic; + function "mod"(Left : Address; Right : Storage_Offset) + return Storage_Offset + with Convention => Intrinsic; + -- Conversion to/from integers: + type Integer_Address is implementation-defined; + function To_Address(Value : Integer_Address) return Address + with Convention => Intrinsic; + function To_Integer(Value : Address) return Integer_Address + with Convention => Intrinsic; +end System.Storage_Elements; + +Storage_Element represents a storage element. Storage_Offset represents an offset in storage elements. +Storage_Count represents a number of storage elements. Storage_Array represents a contiguous sequence +of storage elements. + +Integer_Address is a (signed or modular) integer subtype. To_Address and To_Integer convert back and +forth between this type and Address. + +Storage_Offset'Last shall be greater than or equal to Integer'Last or the largest possible storage offset, +whichever is smaller. Storage_Offset'First shall be <= (–Storage_Offset'Last). + +Implementation Requirements + +Paragraph 15 was deleted. + +37 + +38 + +1 + +2/2 + +3 + +4 + +5 + +6 + +7/3 + +8/3 + +9 + +10/3 + +11/3 + +12 + +13 + +14 + +319 13 December 2012 + +The Package System 13.7 + + Ada Reference Manual — 2012 Edition + +16 + +Operations in System and its children should reflect the target environment semantics as closely as is +reasonable. For example, on most machines, it makes sense for address arithmetic to “wrap around.” +Operations that do not make sense should raise Program_Error. + +Implementation Advice + +1 + +2 + +3/3 + +4/3 + +5/2 + +13.7.2 The Package System.Address_To_Access_Conversions + +The following language-defined generic library package exists: + +Static Semantics + +generic + type Object(<>) is limited private; +package System.Address_To_Access_Conversions is + pragma Preelaborate(Address_To_Access_Conversions); + type Object_Pointer is access all Object; + function To_Pointer(Value : Address) return Object_Pointer + with Convention => Intrinsic; + function To_Address(Value : Object_Pointer) return Address + with Convention => Intrinsic; +end System.Address_To_Access_Conversions; + +The To_Pointer and To_Address subprograms convert back and forth between values of types +Object_Pointer and Address. To_Pointer(X'Address) is equal to X'Unchecked_Access for any X that +allows Unchecked_Access. To_Pointer(Null_Address) returns null. For other addresses, the behavior is +unspecified. To_Address(null) returns Null_Address. To_Address(Y), where Y /= null, returns +Y.all'Address. + +6 + +An implementation may place restrictions on instantiations of Address_To_Access_Conversions. + +Implementation Permissions + +13.8 Machine Code Insertions + +A machine code insertion can be achieved by a call to a subprogram whose sequence_of_statements +contains code_statements. + +code_statement ::= qualified_expression; + +Syntax + +A code_statement is only allowed in the handled_sequence_of_statements of a subprogram_- +body. If a subprogram_body contains any code_statements, then within this subprogram_body the +only allowed form of statement is a code_statement (labeled or not), the only allowed declarative_- +items are use_clauses, and no exception_handler is allowed (comments and pragmas are allowed +as usual). + +The qualified_expression is expected to be of any type. + +Name Resolution Rules + +The qualified_expression shall be of a type declared in package System.Machine_Code. + +Legality Rules + +A code_statement shall appear only within the scope of a with_clause that mentions package +System.Machine_Code. + +1 + +2 + +3 + +4 + +5 + +6 + +13.7.1 The Package System.Storage_Elements + +13 December 2012 320 + + Ada Reference Manual — 2012 Edition + +The contents of the library package System.Machine_Code (if provided) are implementation defined. The +meaning of code_statements is implementation defined. Typically, each qualified_expression represents +a machine instruction or assembly directive. + +Static Semantics + +An implementation may place restrictions on code_statements. An implementation is not required to +provide package System.Machine_Code. + +Implementation Permissions + +NOTES +18 An implementation may provide implementation-defined pragmas specifying register conventions and calling +conventions. + +19 Machine code functions are exempt from the rule that a return statement is required. In fact, return statements are +forbidden, since only code_statements are allowed. + +20 Intrinsic subprograms (see 6.3.1, “Conformance Rules”) can also be used to achieve machine code insertions. Interface +to assembly language can be achieved using the features in Annex B, “Interface to Other Languages”. + +Example of a code statement: + +Examples + +M : Mask; +procedure Set_Mask + with Inline; +procedure Set_Mask is + use System.Machine_Code; -- assume “with System.Machine_Code;” appears somewhere above +begin + SI_Format'(Code => SSM, B => M'Base_Reg, D => M'Disp); + -- Base_Reg and Disp are implementation-defined attributes +end Set_Mask; + +7 + +8 + +9 + +10/2 + +11 + +12 + +13/3 + +14 + +13.9 Unchecked Type Conversions + +An unchecked type conversion can be achieved by a call to an instance of the generic function +Unchecked_Conversion. + +1 + +The following language-defined generic library function exists: + +Static Semantics + +generic + type Source(<>) is limited private; + type Target(<>) is limited private; +function Ada.Unchecked_Conversion(S : Source) return Target + with Convention => Intrinsic; +pragma Pure(Ada.Unchecked_Conversion); + +Dynamic Semantics + +The size of the formal parameter S in an instance of Unchecked_Conversion is that of its subtype. This is +the actual subtype passed to Source, except when the actual is an unconstrained composite subtype, in +which case the subtype is constrained by the bounds or discriminants of the value of the actual expression +passed to S. + +If all of the following are true, the effect of an unchecked conversion is to return the value of an object of +the target subtype whose representation is the same as that of the source object S: + +• S'Size = Target'Size. + +2 + +3/3 + +4 + +5 + +6 + +321 13 December 2012 + +Machine Code Insertions 13.8 + + 7/3 + +8 + +9 + +10 + +11/2 + +Ada Reference Manual — 2012 Edition + +• S'Alignment is a multiple of Target'Alignment or Target'Alignment is zero. +• The target subtype is not an unconstrained composite subtype. +• S and the target subtype both have a contiguous representation. +• The representation of S is a representation of an object of the target subtype. + +Otherwise, if the result type is scalar, the result of the function is implementation defined, and can have an +invalid representation (see 13.9.1). If the result type is nonscalar, the effect is implementation defined; in +particular, the result can be abnormal (see 13.9.1). + +12 + +An implementation may return the result of an unchecked conversion by reference, if the Source type is +not a by-copy type. In this case, the result of the unchecked conversion represents simply a different (read- +only) view of the operand of the conversion. + +Implementation Permissions + +13 + +An implementation may place restrictions on Unchecked_Conversion. + +Implementation Advice + +14/2 + +15 + +Since the Size of an array object generally does not include its bounds, the bounds should not be part of +the converted data. + +The implementation should not generate unnecessary run-time checks to ensure that the representation of +S is a representation of the target type. It should take advantage of the permission to return by reference +when possible. Restrictions on unchecked conversions should be avoided unless required by the target +environment. + +16 + +The recommended level of support for unchecked conversions is: + +17/3 + +• Unchecked conversions should be supported and should be reversible in the cases where this +subclause defines the result. To enable meaningful use of unchecked conversion, a contiguous +representation should be used for elementary subtypes, for statically constrained array subtypes +whose component subtype is one of the subtypes described in this paragraph, and for record +subtypes without discriminants whose component subtypes are described in this paragraph. + +13.9.1 Data Validity + +1 + +2 + +3 + +4 + +5 + +Certain actions that can potentially lead to erroneous execution are not directly erroneous, but instead can +cause objects to become abnormal. Subsequent uses of abnormal objects can be erroneous. + +A scalar object can have an invalid representation, which means that the object's representation does not +represent any value of the object's subtype. The primary cause of invalid representations is uninitialized +variables. + +Abnormal objects and invalid representations are explained in this subclause. + +Dynamic Semantics + +When an object is first created, and any explicit or default initializations have been performed, the object +and all of its parts are in the normal state. Subsequent operations generally leave them normal. However, +an object or part of an object can become abnormal in the following ways: + +• An assignment to the object is disrupted due to an abort (see 9.8) or due to the failure of a + +language-defined check (see 11.6). + +13.9 Unchecked Type Conversions + +13 December 2012 322 + + Ada Reference Manual — 2012 Edition + +• The object is not scalar, and is passed to an in out or out parameter of an imported procedure, +the Read procedure of an instance of Sequential_IO, Direct_IO, or Storage_IO, or the stream +attribute T'Read, if after return from the procedure the representation of the parameter does not +represent a value of the parameter's subtype. + +• The object is the return object of a function call of a nonscalar type, and the function is an +imported function, an instance of Unchecked_Conversion, or the stream attribute T'Input, if after +return from the function the representation of the return object does not represent a value of the +function's subtype. + +6/2 + +6.1/2 + +For an imported object, it is the programmer's responsibility to ensure that the object remains in a normal +state. + +6.2/2 + +Whether or not an object actually becomes abnormal in these cases is not specified. An abnormal object +becomes normal again upon successful completion of an assignment to the object as a whole. + +It is erroneous to evaluate a primary that is a name denoting an abnormal object, or to evaluate a prefix +that denotes an abnormal object. + +Erroneous Execution + +Bounded (Run-Time) Errors + +If the representation of a scalar object does not represent a value of the object's subtype (perhaps because +the object was not initialized), the object is said to have an invalid representation. It is a bounded error to +evaluate the value of such an object. If the error is detected, either Constraint_Error or Program_Error is +raised. Otherwise, execution continues using the invalid representation. The rules of the language outside +this subclause assume that all objects have valid representations. The semantics of operations on invalid +representations are as follows: + +• If the representation of the object represents a value of the object's type, the value of the type is + +used. + +• If the representation of the object does not represent a value of the object's type, the semantics of +operations on such representations is implementation-defined, but does not by itself lead to +erroneous or unpredictable execution, or to other objects becoming abnormal. + +Erroneous Execution + +A call to an imported function or an instance of Unchecked_Conversion is erroneous if the result is scalar, +the result object has an invalid representation, and the result is used other than as the expression of an +an +assignment_statement +object_renaming_declaration, or as the prefix of a Valid attribute. If such a result object is used as the +source of an assignment, and the assigned value is an invalid representation for the target of the +assignment, then any use of the target object prior to a further assignment to the target object, other than as +the prefix of a Valid attribute reference, is erroneous. + +object_declaration, + +object_name + +the + +an + +of + +or + +as + +The dereference of an access value is erroneous if it does not designate an object of an appropriate type or +a subprogram with an appropriate profile, if it designates a nonexistent object, or if it is an access-to- +variable value that designates a constant object and it did not originate from an attribute_reference applied +to an aliased variable view of a controlled or immutably limited object. An access value whose +dereference is erroneous can exist, for example, because of Unchecked_Deallocation, Unchecked_Access, +or Unchecked_Conversion. + +7 + +8 + +9 + +10 + +11 + +12/3 + +13/3 + +NOTES +21 Objects can become abnormal due to other kinds of actions that directly update the object's representation; such +actions are generally considered directly erroneous, however. + +14 + +323 13 December 2012 + +Data Validity 13.9.1 + + Ada Reference Manual — 2012 Edition + +13.9.2 The Valid Attribute + +1 + +2 + +The Valid attribute can be used to check the validity of data produced by unchecked conversion, input, +interface to foreign languages, and the like. + +For a prefix X that denotes a scalar object (after any implicit dereference), the following attribute is +defined: + +Static Semantics + +3/3 + +X'Valid + +Yields True if and only if the object denoted by X is normal, has a valid representation, and +the predicate of the nominal subtype of X evaluates to True. The value of this attribute is of +the predefined type Boolean. + +4 + +5 + +6 + +7 + +8 + +9 + +10 + +11 + +12 + +13/2 + +1 + +2 + +3 + +4 + +5 + +NOTES +22 Invalid data can be created in the following cases (not counting erroneous or unpredictable execution): + +input, + +an uninitialized scalar object, + +the result of an unchecked conversion, + +• +• +• +• +• +• disrupting an assignment due to the failure of a language-defined check (see 11.6), and +• use of an object whose Address has been specified. + +interface to another language (including machine code), + +aborting an assignment, + +23 X'Valid is not considered to be a read of X; hence, it is not an error to check the validity of invalid data. + +24 The Valid attribute may be used to check the result of calling an instance of Unchecked_Conversion (or any other +operation that can return invalid values). However, an exception handler should also be provided because implementations +are permitted to raise Constraint_Error or Program_Error if they detect the use of an invalid representation (see 13.9.1). + +13.10 Unchecked Access Value Creation + +The attribute Unchecked_Access is used to create access values in an unsafe manner — the programmer is +responsible for preventing “dangling references.” + +The following attribute is defined for a prefix X that denotes an aliased view of an object: + +Static Semantics + +X'Unchecked_Access + +rules and semantics + +to +All +X'Unchecked_Access, except that, for the purposes of accessibility rules and checks, it is as +if X were declared immediately within a library package. + +(see 3.10.2) apply also + +to X'Access + +that apply + +NOTES +25 This attribute is provided to support the situation where a local object is to be inserted into a global linked data +structure, when the programmer knows that it will always be removed from the data structure prior to exiting the object's +scope. The Access attribute would be illegal in this case (see 3.10.2, “Operations of Access Types”). + +26 There is no Unchecked_Access attribute for subprograms. + +13.9.2 The Valid Attribute + +13 December 2012 324 + + + Ada Reference Manual — 2012 Edition + +13.11 Storage Management + +Each access-to-object type has an associated storage pool. The storage allocated by an allocator comes +from the pool; instances of Unchecked_Deallocation return storage to the pool. Several access types can +share the same pool. + +A storage pool is a variable of a type in the class rooted at Root_Storage_Pool, which is an abstract limited +controlled type. By default, the implementation chooses a standard storage pool for each access-to-object +type. The user may define new pool types, and may override the choice of pool for an access-to-object +type by specifying Storage_Pool for the type. + +If Storage_Pool is specified for a given access type, Storage_Size shall not be specified for it. + +Legality Rules + +The following language-defined library package exists: + +Static Semantics + +with Ada.Finalization; +with System.Storage_Elements; +package System.Storage_Pools is + pragma Preelaborate(System.Storage_Pools); + type Root_Storage_Pool is + abstract new Ada.Finalization.Limited_Controlled with private; + pragma Preelaborable_Initialization(Root_Storage_Pool); + procedure Allocate( + Pool : in out Root_Storage_Pool; + Storage_Address : out Address; + Size_In_Storage_Elements : in Storage_Elements.Storage_Count; + Alignment : in Storage_Elements.Storage_Count) is abstract; + procedure Deallocate( + Pool : in out Root_Storage_Pool; + Storage_Address : in Address; + Size_In_Storage_Elements : in Storage_Elements.Storage_Count; + Alignment : in Storage_Elements.Storage_Count) is abstract; + function Storage_Size(Pool : Root_Storage_Pool) + return Storage_Elements.Storage_Count is abstract; +private + ... -- not specified by the language +end System.Storage_Pools; + +A storage pool type (or pool type) is a descendant of Root_Storage_Pool. The elements of a storage pool +are the objects allocated in the pool by allocators. + +For every access-to-object subtype S, the following representation attributes are defined: + +S'Storage_Pool + +Denotes the storage pool of the type of S. The type of this attribute is Root_Storage_- +Pool'Class. + +S'Storage_Size + +Yields the result of calling Storage_Size(S'Storage_Pool), which is intended to be a +measure of the number of storage elements reserved for the pool. The type of this attribute +is universal_integer. + +Storage_Size or Storage_Pool may be specified for a nonderived access-to-object type via an attribute_- +definition_clause; the name in a Storage_Pool clause shall denote a variable. + +1 + +2/2 + +3 + +4 + +5 + +6/2 + +7 + +8 + +9 + +10 + +11 + +12/2 + +13 + +14 + +15 + +325 13 December 2012 + +Storage Management 13.11 + + + + Ada Reference Manual — 2012 Edition + +16/3 + +An allocator of a type T that does not support subpools allocates storage from T's storage pool. If the +storage pool is a user-defined object, then the storage is allocated by calling Allocate as described below. +Allocators for types that support subpools are described in 13.11.4. + +17 + +18 + +19 + +20 + +21 + +If Storage_Pool is not specified for a type defined by an access_to_object_definition, then the +implementation chooses a standard storage pool for it in an implementation-defined manner. In this case, +the exception Storage_Error is raised by an allocator if there is not enough storage. It is implementation +defined whether or not the implementation provides user-accessible names for the standard pool type(s). + +If Storage_Size is specified for an access type, then the Storage_Size of this pool is at least that requested, +and the storage for the pool is reclaimed when the master containing the declaration of the access type is +left. If the implementation cannot satisfy the request, Storage_Error is raised at the point of the attribute_- +definition_clause. If neither Storage_Pool nor Storage_Size are specified, then the meaning of +Storage_Size is implementation defined. + +If Storage_Pool is specified for an access type, then the specified pool is used. + +The effect of calling Allocate and Deallocate for a standard storage pool directly (rather than implicitly via +an allocator or an instance of Unchecked_Deallocation) is unspecified. + +Erroneous Execution + +If Storage_Pool is specified for an access type, then if Allocate can satisfy the request, it should allocate a +contiguous block of memory, and return the address of the first storage element in Storage_Address. The +block should contain Size_In_Storage_Elements storage elements, and should be aligned according to +Alignment. The allocated storage should not be used for any other purpose while the pool element remains +in existence. If the request cannot be satisfied, then Allocate should propagate an exception (such as +Storage_Error). If Allocate behaves in any other manner, then the program execution is erroneous. + +Implementation Requirements + +21.1/3 + +21.2/3 + +21.3/3 + +The Allocate procedure of a user-defined storage pool object P may be called by the implementation only +to allocate storage for a type T whose pool is P, only at the following points: + +• During the execution of an allocator of type T; +• During the execution of a return statement for a function whose result is built-in-place in the + +result of an allocator of type T; + +21.4/3 + +• During the execution of an assignment operation with a target of an allocated object of type T + +with a part that has an unconstrained discriminated subtype with defaults. + +21.5/3 + +For each of the calls of Allocate described above, P (equivalent to T'Storage_Pool) is passed as the Pool +parameter. The Size_In_Storage_Elements parameter indicates the number of storage elements to be +allocated, and is no more than D'Max_Size_In_Storage_Elements, where D is the designated subtype of T. +The Alignment parameter is a nonzero integral multiple of D'Alignment if D is a specific type, and +otherwise is a nonzero integral multiple of the alignment of the specific type identified by the tag of the +object being created; it is unspecified if there is no such value. The Alignment parameter is no more than +D'Max_Alignment_For_Allocation. The result returned in the Storage_Address parameter is used as the +address of the allocated storage, which is a contiguous block of memory of Size_In_Storage_Elements +storage elements. Any exception propagated by Allocate is propagated by the construct that contained the +call. + +21.6/3 + +The number of calls to Allocate needed to implement an allocator for any particular type is unspecified. +The number of calls to Deallocate needed to implement an instance of Unchecked_Deallocation (see +13.11.2) for any particular object is the same as the number of Allocate calls for that object. + +13.11 Storage Management + +13 December 2012 326 + + Ada Reference Manual — 2012 Edition + +The Deallocate procedure of a user-defined storage pool object P may be called by the implementation to +deallocate storage for a type T whose pool is P only at the places when an Allocate call is allowed for P, +during the execution of an instance of Unchecked_Deallocation for T, or as part of the finalization of the +collection of T. For such a call of Deallocate, P (equivalent to T'Storage_Pool) is passed as the Pool +parameter. The value of the Storage_Address parameter for a call to Deallocate is the value returned in the +Storage_Address parameter of the corresponding successful call to Allocate. The values of the +Size_In_Storage_Elements and Alignment parameters are the same values passed to the corresponding +Allocate call. Any exception propagated by Deallocate is propagated by the construct that contained the +call. + +An implementation shall document the set of values that a user-defined Allocate procedure needs to accept +for the Alignment parameter. An implementation shall document how the standard storage pool is chosen, +and how storage is allocated by standard storage pools. + +Documentation Requirements + +Implementation Advice + +An implementation should document any cases in which it dynamically allocates heap storage for a +purpose other than the evaluation of an allocator. + +A default (implementation-provided) storage pool for an access-to-constant type should not have overhead +to support deallocation of individual objects. + +The storage pool used for an allocator of an anonymous access type should be determined as follows: +• If the allocator is defining a coextension (see 3.10.2) of an object being created by an outer +allocator, then the storage pool used for the outer allocator should also be used for the +coextension; + +• For other access discriminants and access parameters, the storage pool should be created at the + +point of the allocator, and be reclaimed when the allocated object becomes inaccessible; + +• If the allocator defines the result of a function with an access result, the storage pool is +determined as though the allocator were in place of the call of the function. If the call is the +operand of a type conversion, the storage pool is that of the target access type of the conversion. +If the call is itself defining the result of a function with an access result, this rule is applied +recursively; + +21.7/3 + +22 + +23 + +24 + +25/2 + +25.1/2 + +25.2/2 + +25.3/3 + +• Otherwise, a default storage pool should be created at the point where the anonymous access + +25.4/2 + +type is elaborated; such a storage pool need not support deallocation of individual objects. + +NOTES +27 A user-defined storage pool type can be obtained by extending the Root_Storage_Pool type, and overriding the +primitive subprograms Allocate, Deallocate, and Storage_Size. A user-defined storage pool can then be obtained by +declaring an object of the type extension. The user can override Initialize and Finalize if there is any need for nontrivial +initialization and finalization for a user-defined pool type. For example, Finalize might reclaim blocks of storage that are +allocated separately from the pool object itself. + +28 The writer of the user-defined allocation and deallocation procedures, and users of allocators for the associated access +type, are responsible for dealing with any interactions with tasking. In particular: + +• +• +• + +If the allocators are used in different tasks, they require mutual exclusion. + +If they are used inside protected objects, they cannot block. + +If they are used by interrupt handlers (see C.3, “Interrupt Support”), the mutual exclusion mechanism has to +work properly in that context. + +29 The primitives Allocate, Deallocate, and Storage_Size are declared as abstract (see 3.9.3), and therefore they have to +be overridden when a new (nonabstract) storage pool type is declared. + +26 + +27 + +28 + +29 + +30 + +31 + +327 13 December 2012 + +Storage Management 13.11 + + Ada Reference Manual — 2012 Edition + +To associate an access type with a storage pool object, the user first declares a pool object of some type +derived from Root_Storage_Pool. Then, the user defines its Storage_Pool attribute, as follows: + +Examples + +Pool_Object : Some_Storage_Pool_Type; +type T is access Designated; +for T'Storage_Pool use Pool_Object; + +Another access type may be added to an existing storage pool, via: + +for T2'Storage_Pool use T'Storage_Pool; + +The semantics of this is implementation defined for a standard storage pool. + +As usual, a derivative of Root_Storage_Pool may define additional operations. For example, consider the +Mark_Release_Pool_Type defined in 13.11.6, that has two additional operations, Mark and Release, the +following is a possible use: + +type Mark_Release_Pool_Type + (Pool_Size : Storage_Elements.Storage_Count) + is new Subpools.Root_Storage_Pool_With_Subpools with private; + -- As defined in package MR_Pool, see 13.11.6 +... + +Our_Pool : Mark_Release_Pool_Type (Pool_Size => 2000); +My_Mark : MR_Pool.Subpool_Handle; -- See 13.11.6 +type Acc is access ...; +for Acc'Storage_Pool use Our_Pool; +... + +My_Mark := Mark(Our_Pool); +... -- Allocate objects using “new (My_Mark) Designated(...)”. +Release(My_Mark); -- Finalize objects and reclaim storage. + +32 + +33 + +34 + +35 + +36 + +37 + +38/3 + +39/3 + +40 + +41/3 + +42/3 + +43/3 + +13.11.1 Storage Allocation Attributes + +1/3 + +The Max_Size_In_Storage_Elements and Max_Alignment_For_Allocation attributes may be useful in +writing user-defined pool types. + +2/3 + +3/3 + +For every subtype S, the following attributes are defined: + +S'Max_Size_In_Storage_Elements + +Static Semantics + +Denotes the maximum value for Size_In_Storage_Elements that could be requested by the +implementation via Allocate for an access type whose designated subtype is S. The value of +this attribute is of type universal_integer. + +4/3 + +S'Max_Alignment_For_Allocation + +Denotes the maximum value for Alignment that could be requested by the implementation +via Allocate for an access type whose designated subtype is S. The value of this attribute is +of type universal_integer. + +5/3 + +For a type with access discriminants, if the implementation allocates space for a coextension in the same +pool as that of the object having the access discriminant, then these attributes account for any calls on +Allocate that could be performed to provide space for such coextensions. + +13.11 Storage Management + +13 December 2012 328 + + + + Ada Reference Manual — 2012 Edition + +13.11.2 Unchecked Storage Deallocation + +Unchecked storage deallocation of an object designated by a value of an access type is achieved by a call +to an instance of the generic procedure Unchecked_Deallocation. + +1 + +Static Semantics + +The following language-defined generic library procedure exists: + +generic + type Object(<>) is limited private; + type Name is access Object; +procedure Ada.Unchecked_Deallocation(X : in out Name) + with Convention => Intrinsic; +pragma Preelaborate(Ada.Unchecked_Deallocation); + +Legality Rules + +2 + +3/3 + +A call on an instance of Unchecked_Deallocation is illegal if the actual access type of the instance is a +type for which the Storage_Size has been specified by a static expression with value zero or is defined by +the language to be zero. In addition to the places where Legality Rules normally apply (see 12.3), this rule +applies also in the private part of an instance of a generic unit. + +3.1/3 + +Given an instance of Unchecked_Deallocation declared as follows: + +procedure Free is + new Ada.Unchecked_Deallocation( + object_subtype_name, access_to_variable_subtype_name); + +Dynamic Semantics + +Procedure Free has the following effect: + +1. After executing Free(X), the value of X is null. + +2. Free(X), when X is already equal to null, has no effect. + +3. Free(X), when X is not equal to null first performs finalization of the object designated by X +(and any coextensions of the object — see 3.10.2), as described in 7.6.1. It then deallocates the +storage occupied by the object designated by X (and any coextensions). If the storage pool is a +user-defined object, then the storage is deallocated by calling Deallocate as described in 13.11. +There is one exception: if the object being freed contains tasks, the object might not be +deallocated. + +4 + +5 + +6 + +7 + +8 + +9/3 + +After Free(X), the object designated by X, and any subcomponents (and coextensions) thereof, no longer +exist; their storage can be reused for other purposes. + +10/2 + +Bounded (Run-Time) Errors + +It is a bounded error to free a discriminated, unterminated task object. The possible consequences are: + +• No exception is raised. +• Program_Error or Tasking_Error is raised at the point of the deallocation. +• Program_Error or Tasking_Error is raised in the task the next time it references any of the + +discriminants. + +In the first two cases, the storage for the discriminants (and for any enclosing object if it is designated by +an access discriminant of the task) is not reclaimed prior to task termination. + +11 + +12 + +13 + +14 + +15 + +329 13 December 2012 + +Unchecked Storage Deallocation 13.11.2 + + Ada Reference Manual — 2012 Edition + +16/3 + +Evaluating a name that denotes a nonexistent object, or a protected subprogram or subprogram renaming +whose associated object (if any) is nonexistent, is erroneous. The execution of a call to an instance of +Unchecked_Deallocation is erroneous if the object was created other than by an allocator for an access +type whose pool is Name'Storage_Pool. + +Erroneous Execution + +17 + +For a standard storage pool, Free should actually reclaim the storage. + +Implementation Advice + +17.1/3 + +A call on an instance of Unchecked_Deallocation with a nonnull access value should raise Program_Error +if the actual access type of the instance is a type for which the Storage_Size has been specified to be zero +or is defined by the language to be zero. + +18 + +19 + +NOTES +30 The rules here that refer to Free apply to any instance of Unchecked_Deallocation. + +31 Unchecked_Deallocation cannot be instantiated for an access-to-constant type. This is implied by the rules of 12.5.4. + +13.11.3 Default Storage Pools + +1/3 + +This paragraph was deleted. + +2/3 + +3/3 + +3.1/3 + +3.2/3 + +The form of a pragma Default_Storage_Pool is as follows: + pragma Default_Storage_Pool (storage_pool_indicator); + +storage_pool_indicator ::= storage_pool_name | null + +Syntax + +A pragma Default_Storage_Pool is allowed immediately within the visible part of a +package_specification, immediately within a declarative_part, or as a configuration pragma. + +3.3/3 + +The storage_pool_name is expected to be of type Root_Storage_Pool'Class. + +Name Resolution Rules + +4/3 + +The storage_pool_name shall denote a variable. + +Legality Rules + +4.1/3 + +If the pragma is used as a configuration pragma, the storage_pool_indicator shall be null, and it defines +the default pool to be null within all applicable compilation units (see 10.1.5), except within the +immediate scope of another pragma Default_Storage_Pool. Otherwise, the pragma occurs immediately +within a sequence of declarations, and it defines the default pool within the immediate scope of the pragma +to be either null or the pool denoted by the storage_pool_name, except within the immediate scope of a +later pragma Default_Storage_Pool. Thus, an inner pragma overrides an outer one. + +4.2/3 + +A pragma Default_Storage_Pool shall not be used as a configuration pragma that applies to a compilation +unit that is within the immediate scope of another pragma Default_Storage_Pool. + +Static Semantics + +5/3 + +The language-defined aspect Default_Storage_Pool may be specified for a generic instance; it defines the +default pool for access types within an instance. The expected type for the Default_Storage_Pool aspect is +Root_Storage_Pool'Class. The aspect_definition must be a name that denotes a variable. This aspect +overrides any Default_Storage_Pool pragma that might apply to the generic unit; if the aspect is not +specified, the default pool of the instance is that defined for the generic unit. + +13.11.2 Unchecked Storage Deallocation + +13 December 2012 330 + + Ada Reference Manual — 2012 Edition + +For nonderived access types declared in places where the default pool is defined by the pragma or aspect, +their Storage_Pool or Storage_Size attribute is determined as follows, unless Storage_Pool or +Storage_Size is specified for the type: + +• If the default pool is null, the Storage_Size attribute is defined by the language to be zero. + +Therefore, an allocator for such a type is illegal. + +• If the default pool is nonnull, the Storage_Pool attribute is that pool. + +Otherwise, there is no default pool; the standard storage pool is used for the type as described in 13.11. + +This paragraph was deleted. + +Implementation Permissions + +An object created by an allocator that is passed as the actual parameter to an access parameter may be +allocated on the stack, and automatically reclaimed, regardless of the default pool.. + +NOTES +32 Default_Storage_Pool may be used with restrictions No_Coextensions and No_Access_Parameter_Allocators (see +H.4) to ensure that all allocators use the default pool. + +13.11.4 Storage Subpools + +This subclause defines a package to support the partitioning of a storage pool into subpools. A subpool +may be specified as the default to be used for allocation from the associated storage pool, or a particular +subpool may be specified as part of an allocator (see 4.8). + +The following language-defined library package exists: + +Static Semantics + +package System.Storage_Pools.Subpools is + pragma Preelaborate (Subpools); + type Root_Storage_Pool_With_Subpools is + abstract new Root_Storage_Pool with private; + type Root_Subpool is abstract tagged limited private; + type Subpool_Handle is access all Root_Subpool'Class; + for Subpool_Handle'Storage_Size use 0; + function Create_Subpool (Pool : in out Root_Storage_Pool_With_Subpools) + return not null Subpool_Handle is abstract; + -- The following operations are intended for pool implementers: + function Pool_of_Subpool (Subpool : not null Subpool_Handle) + return access Root_Storage_Pool_With_Subpools'Class; + procedure Set_Pool_of_Subpool ( + Subpool : in not null Subpool_Handle; + To : in out Root_Storage_Pool_With_Subpools'Class); + procedure Allocate_From_Subpool ( + Pool : in out Root_Storage_Pool_With_Subpools; + Storage_Address : out Address; + Size_In_Storage_Elements : in Storage_Elements.Storage_Count; + Alignment : in Storage_Elements.Storage_Count; + Subpool : in not null Subpool_Handle) is abstract + with Pre'Class => Pool_of_Subpool(Subpool) = Pool'Access; + procedure Deallocate_Subpool ( + Pool : in out Root_Storage_Pool_With_Subpools; + Subpool : in out Subpool_Handle) is abstract + with Pre'Class => Pool_of_Subpool(Subpool) = Pool'Access; + +6/3 + +6.1/3 + +6.2/3 + +6.3/3 + +7/3 + +8/3 + +9/3 + +1/3 + +2/3 + +3/3 + +4/3 + +5/3 + +6/3 + +7/3 + +8/3 + +9/3 + +10/3 + +11/3 + +12/3 + +331 13 December 2012 + +Default Storage Pools 13.11.3 + + 13/3 + +14/3 + +15/3 + +16/3 + +17/3 + +18/3 + +19/3 + +20/3 + +21/3 + +22/3 + +23/3 + +Ada Reference Manual — 2012 Edition + + function Default_Subpool_for_Pool ( + Pool : in out Root_Storage_Pool_With_Subpools) + return not null Subpool_Handle; + overriding + procedure Allocate ( + Pool : in out Root_Storage_Pool_With_Subpools; + Storage_Address : out Address; + Size_In_Storage_Elements : in Storage_Elements.Storage_Count; + Alignment : in Storage_Elements.Storage_Count); + overriding + procedure Deallocate ( + Pool : in out Root_Storage_Pool_With_Subpools; + Storage_Address : in Address; + Size_In_Storage_Elements : in Storage_Elements.Storage_Count; + Alignment : in Storage_Elements.Storage_Count) is null; + overriding + function Storage_Size (Pool : Root_Storage_Pool_With_Subpools) + return Storage_Elements.Storage_Count + is (Storage_Elements.Storage_Count'Last); +private + ... -- not specified by the language +end System.Storage_Pools.Subpools; + +A subpool is a separately reclaimable portion of a storage pool, identified by an object of type +Subpool_Handle (a subpool handle). A subpool handle also identifies the enclosing storage pool, a storage +pool +from +Root_Storage_Pool_With_Subpools. A subpool is created by calling Create_Subpool or a similar +constructor; the constructor returns the subpool handle. + +that supports subpools, which + +is a storage pool whose + +is descended + +type + +A subpool object is an object of a type descended from Root_Subpool. Typically, subpool objects are +managed by the containing storage pool; only the handles need be exposed to clients of the storage pool. +Subpool objects are designated by subpool handles, and are the run-time representation of a subpool. + +Each subpool belongs to a single storage pool (which will always be a pool that supports subpools). An +access to the pool that a subpool belongs to can be obtained by calling Pool_of_Subpool with the subpool +handle. Set_Pool_of_Subpool causes the subpool of the subpool handle to belong to the given pool; this is +intended to be called from subpool constructors like Create_Subpool. Set_Pool_of_Subpool propagates +Program_Error if the subpool already belongs to a pool. + +When an allocator for a type whose storage pool supports subpools is evaluated, a call is made on +Allocate_From_Subpool passing in a Subpool_Handle, in addition to the parameters as defined for calls on +Allocate (see 13.11). The subpool designated by the subpool_handle_name is used, if specified in an +allocator. Otherwise, Default_Subpool_for_Pool of the Pool is used to provide a subpool handle. All +requirements on the Allocate procedure also apply to Allocate_from_Subpool. + +Legality Rules + +If a storage pool that supports subpools is specified as the Storage_Pool for an access type, the access type +is called a subpool access type. A subpool access type shall be a pool-specific access type. + +The accessibility level of a subpool access type shall not be statically deeper than that of the storage pool +object. If the specified storage pool object is a storage pool that supports subpools, then the name that +denotes the object shall not denote part of a formal parameter, nor shall it denote part of a dereference of a +value of a non-library-level general access type. In addition to the places where Legality Rules normally +apply (see 12.3), these rules also apply in the private part of an instance of a generic unit. + +13.11.4 Storage Subpools + +13 December 2012 332 + + Ada Reference Manual — 2012 Edition + +Dynamic Semantics + +When an access type with a specified storage pool is frozen (see 13.14), if the tag of the storage pool +object identifies a storage pool that supports subpools, the following checks are made: + +• + +• + +the name used to specify the storage pool object does not denote part of a formal parameter nor +part of a dereference of a value of a non-library-level general access type; and + +the accessibility level of the access type is not deeper than that of the storage pool object. + +Program_Error is raised if either of these checks fail. + +A call to Subpools.Allocate(P, Addr, Size, Align) does the following: + +Allocate_From_Subpool + (Root_Storage_Pool_With_Subpools'Class(P), + Addr, Size, Align, + Subpool => Default_Subpool_for_Pool + (Root_Storage_Pool_With_Subpools'Class(P))); + +An allocator that allocates in a subpool raises Program_Error if the allocated object has task parts. + +Unless overridden, Default_Subpool_for_Pool propagates Program_Error. + +When an allocator for a type whose storage pool is of type Root_Storage_Pool'Class is evaluated, but +supports subpools, the implementation may call Allocate rather than Allocate_From_Subpool. This will +have the same effect, so long as Allocate has not been overridden. + +Implementation Permissions + +NOTES +the +33 A user-defined +storage pool +Root_Storage_Pool_With_Subpools +subprograms Create_Subpool, +overriding +Allocate_From_Subpool, and Deallocate_Subpool. Create_Subpool should call Set_Pool_Of_Subpool before returning +the subpool handle. To make use of such a pool, a user would declare an object of the type extension, use it to define the +Storage_Pool attribute of one or more access types, and then call Create_Subpool to obtain subpool handles associated +with the pool. + +that supports subpools can be + +implemented by extending + +type +type, + +primitive + +and + +the + +34 A user-defined storage pool type that supports subpools may define additional subpool constructors similar to +Create_Subpool (these typically will have additional parameters). + +35 The pool implementor should override Default_Subpool_For_Pool if the pool is to support a default subpool for the +pool. The implementor can override Deallocate if individual object reclamation is to be supported, and can override +Storage_Size if there is some limit on the total size of the storage pool. The implementor can override Initialize and +Finalize if there is any need for nontrivial initialization and finalization for the pool as a whole. For example, Finalize +might reclaim blocks of storage that are allocated over and above the space occupied by the pool object itself. The pool +implementor may extend the Root_Subpool type as necessary to carry additional information with each subpool provided +by Create_Subpool. + +13.11.5 Subpool Reclamation + +A subpool may be explicitly deallocated using Unchecked_Deallocate_Subpool. + +The following language-defined library procedure exists: +with System.Storage_Pools.Subpools; +procedure Ada.Unchecked_Deallocate_Subpool + (Subpool : in out System.Storage_Pools.Subpools.Subpool_Handle); + +Static Semantics + +If Subpool is null, a call on Unchecked_Deallocate_Subpool has no effect. Otherwise, the subpool is +finalized, and Subpool is set to null. + +333 13 December 2012 + +Storage Subpools 13.11.4 + +24/3 + +25/3 + +26/3 + +27/3 + +28/3 + +29/3 + +30/3 + +31/3 + +32/3 + +33/3 + +34/3 + +35/3 + +1/3 + +2/3 + +3/3 + +4/3 + + Ada Reference Manual — 2012 Edition + +Finalization of a subpool has the following effects: +• The subpool no longer belongs to any pool; +• Any of the objects allocated from the subpool that still exist are finalized in an arbitrary order; +• The following dispatching call is then made: + + Deallocate_Subpool(Pool_of_Subpool(Subpool).all, Subpool); + +Finalization of a Root_Storage_Pool_With_Subpools object finalizes all subpools that belong to that pool +that have not yet been finalized. + +13.11.6 Storage Subpool Example + +Examples + +The following example is a simple but complete implementation of the classic Mark/Release pool using +subpools: + +with System.Storage_Pools.Subpools; +with System.Storage_Elements; +with Ada.Unchecked_Deallocate_Subpool; +package MR_Pool is + use System.Storage_Pools; + -- For uses of Subpools. + use System.Storage_Elements; + -- For uses of Storage_Count and Storage_Array. + -- Mark and Release work in a stack fashion, and allocations are not allowed + -- from a subpool other than the one at the top of the stack. This is also + -- the default pool. + subtype Subpool_Handle is Subpools.Subpool_Handle; + type Mark_Release_Pool_Type (Pool_Size : Storage_Count) is new + Subpools.Root_Storage_Pool_With_Subpools with private; + function Mark (Pool : in out Mark_Release_Pool_Type) + return not null Subpool_Handle; + procedure Release (Subpool : in out Subpool_Handle) renames + Ada.Unchecked_Deallocate_Subpool; +private + type MR_Subpool is new Subpools.Root_Subpool with record + Start : Storage_Count; + end record; + subtype Subpool_Indexes is Positive range 1 .. 10; + type Subpool_Array is array (Subpool_Indexes) of aliased MR_Subpool; + type Mark_Release_Pool_Type (Pool_Size : Storage_Count) is new + Subpools.Root_Storage_Pool_With_Subpools with record + Storage : Storage_Array (0 .. Pool_Size-1); + Next_Allocation : Storage_Count := 0; + Markers : Subpool_Array; + Current_Pool : Subpool_Indexes := 1; + end record; + overriding + function Create_Subpool (Pool : in out Mark_Release_Pool_Type) + return not null Subpool_Handle; + function Mark (Pool : in out Mark_Release_Pool_Type) + return not null Subpool_Handle renames Create_Subpool; + +5/3 + +6/3 + +7/3 + +8/3 + +9/3 + +10/3 + +1/3 + +2/3 + +3/3 + +4/3 + +5/3 + +6/3 + +7/3 + +8/3 + +9/3 + +10/3 + +11/3 + +12/3 + +13/3 + +13.11.5 Subpool Reclamation + +13 December 2012 334 + + Ada Reference Manual — 2012 Edition + + overriding + procedure Allocate_From_Subpool ( + Pool : in out Mark_Release_Pool_Type; + Storage_Address : out System.Address; + Size_In_Storage_Elements : in Storage_Count; + Alignment : in Storage_Count; + Subpool : not null Subpool_Handle); + overriding + procedure Deallocate_Subpool ( + Pool : in out Mark_Release_Pool_Type; + Subpool : in out Subpool_Handle); + overriding + function Default_Subpool_for_Pool (Pool : in out Mark_Release_Pool_Type) + return not null Subpool_Handle; + overriding + procedure Initialize (Pool : in out Mark_Release_Pool_Type); + -- We don't need Finalize. +end MR_Pool; +package body MR_Pool is + use type Subpool_Handle; + procedure Initialize (Pool : in out Mark_Release_Pool_Type) is + -- Initialize the first default subpool. + begin + Pool.Markers(1).Start := 1; + Subpools.Set_Pool_of_Subpool + (Pool.Markers(1)'Unchecked_Access, Pool); + end Initialize; + function Create_Subpool (Pool : in out Mark_Release_Pool_Type) + return not null Subpool_Handle is + -- Mark the current allocation location. + begin + if Pool.Current_Pool = Subpool_Indexes'Last then + raise Storage_Error; -- No more subpools. + end if; + Pool.Current_Pool := Pool.Current_Pool + 1; -- Move to the next subpool + return Result : constant not null Subpool_Handle := + Pool.Markers(Pool.Current_Pool)'Unchecked_Access + do + Pool.Markers(Pool.Current_Pool).Start := Pool.Next_Allocation; + Subpools.Set_Pool_of_Subpool (Result, Pool); + end return; + end Create_Subpool; + procedure Deallocate_Subpool ( + Pool : in out Mark_Release_Pool_Type; + Subpool : in out Subpool_Handle) is + begin + if Subpool /= Pool.Markers(Pool.Current_Pool)'Unchecked_Access then + raise Program_Error; -- Only the last marked subpool can be released. + end if; + if Pool.Current_Pool /= 1 then + Pool.Next_Allocation := Pool.Markers(Pool.Current_Pool).Start; + Pool.Current_Pool := Pool.Current_Pool - 1; -- Move to the previous subpool + else -- Reinitialize the default subpool: + Pool.Next_Allocation := 1; + Subpools.Set_Pool_of_Subpool + (Pool.Markers(1)'Unchecked_Access, Pool); + end if; + end Deallocate_Subpool; + +14/3 + +15/3 + +16/3 + +17/3 + +18/3 + +19/3 + +20/3 + +21/3 + +22/3 + +23/3 + +24/3 + +25/3 + +335 13 December 2012 + +Storage Subpool Example 13.11.6 + + Ada Reference Manual — 2012 Edition + + function Default_Subpool_for_Pool (Pool : in out Mark_Release_Pool_Type) + return not null Subpool_Handle is + begin + return Pool.Markers(Pool.Current_Pool)'Unchecked_Access; + end Default_Subpool_for_Pool; + procedure Allocate_From_Subpool ( + Pool : in out Mark_Release_Pool_Type; + Storage_Address : out System.Address; + Size_In_Storage_Elements : in Storage_Count; + Alignment : in Storage_Count; + Subpool : not null Subpool_Handle) is + begin + if Subpool /= Pool.Markers(Pool.Current_Pool)'Unchecked_Access then + raise Program_Error; -- Only the last marked subpool can be used for allocations. + end if; + -- Correct the alignment if necessary: + Pool.Next_Allocation := Pool.Next_Allocation + + ((-Pool.Next_Allocation) mod Alignment); + if Pool.Next_Allocation + Size_In_Storage_Elements > + Pool.Pool_Size then + raise Storage_Error; -- Out of space. + end if; + Storage_Address := Pool.Storage (Pool.Next_Allocation)'Address; + Pool.Next_Allocation := + Pool.Next_Allocation + Size_In_Storage_Elements; + end Allocate_From_Subpool; +end MR_Pool; + +13.12 Pragma Restrictions and Pragma Profile + +A pragma Restrictions expresses the user's intent to abide by certain restrictions. A pragma Profile +expresses the user's intent to abide by a set of Restrictions or other specified run-time policies. These may +facilitate the construction of simpler run-time environments. + +The form of a pragma Restrictions is as follows: + pragma Restrictions(restriction{, restriction}); + +Syntax + +restriction ::= restriction_identifier + | restriction_parameter_identifier => restriction_parameter_argument + +26/3 + +27/3 + +28/3 + +29/3 + +1/3 + +2 + +3 + +4/2 + +4.1/2 + +restriction_parameter_argument ::= name | expression + +Name Resolution Rules + +5 + +6 + +Unless otherwise specified for a particular restriction, the expression is expected to be of any integer type. + +Unless otherwise specified for a particular restriction, the expression shall be static, and its value shall be +nonnegative. + +Legality Rules + +Paragraph 7 was deleted. + +8/3 + +A pragma Restrictions is a configuration pragma. If a pragma Restrictions applies to any compilation unit +included in the partition, this may impose either (or both) of two kinds of requirements, as specified for the +particular restriction: + +Post-Compilation Rules + +13.11.6 Storage Subpool Example + +13 December 2012 336 + + Ada Reference Manual — 2012 Edition + +• A restriction may impose requirements on some or all of the units comprising the partition. +Unless otherwise specified for a particular restriction, such a requirement applies to all of the +units comprising the partition and is enforced via a post-compilation check. + +• A restriction may impose requirements on the run-time behavior of the program, as indicated by + +the specification of run-time behavior associated with a violation of the requirement. + +For the purpose of checking whether a partition contains constructs that violate any restriction (unless +specified otherwise for a particular restriction): + +• Generic instances are logically expanded at the point of instantiation; +• If an object of a type is declared or allocated and not explicitly initialized, then all expressions + +appearing in the definition for the type and any of its ancestors are presumed to be used; + +• A default_expression for a formal parameter or a generic formal object is considered to be used +if and only if the corresponding actual parameter is not provided in a given call or instantiation. + +Implementation Permissions + +An implementation may provide implementation-defined restrictions; the identifier for an implementation- +defined restriction shall differ from those of the language-defined restrictions. + +An implementation may place limitations on the values of the expression that are supported, and +limitations on the supported combinations of restrictions. The consequences of violating such limitations +are implementation defined. + +An implementation is permitted to omit restriction checks for code that is recognized at compile time to be +unreachable and for which no code is generated. + +Whenever enforcement of a restriction is not required prior to execution, an implementation may +nevertheless enforce the restriction prior to execution of a partition to which the restriction applies, +provided that every execution of the partition would violate the restriction. + +The form of a pragma Profile is as follows: + pragma Profile (profile_identifier {, profile_pragma_argument_association}); + +Syntax + +The profile_identifier shall be the name of a usage profile. The semantics of any profile_pragma_- +argument_associations are defined by the usage profile specified by the profile_identifier. + +Legality Rules + +8.1/3 + +8.2/3 + +8.3/1 + +8.4/1 + +8.5/1 + +8.6/1 + +8.7/3 + +9 + +9.1/1 + +9.2/1 + +10/3 + +11/3 + +12/3 + +A profile is equivalent to the set of configuration pragmas that is defined for each usage profile. + +13/3 + +Static Semantics + +A pragma Profile is a configuration pragma. There may be more than one pragma Profile for a partition. + +14/3 + +Post-Compilation Rules + +Implementation Permissions + +implementation may provide + +An +implementation-defined usage profile shall differ from those of the language-defined usage profiles. + +implementation-defined usage profiles; + +the + +identifier for an + +NOTES +36 Restrictions intended to facilitate the construction of efficient tasking run-time systems are defined in D.7. Restrictions +intended for use when constructing high integrity systems are defined in H.4. + +337 13 December 2012 + +Pragma Restrictions and Pragma Profile 13.12 + +15/3 + +16/2 + + Ada Reference Manual — 2012 Edition + +17 + +37 An implementation has to enforce the restrictions in cases where enforcement is required, even if it chooses not to take +advantage of the restrictions in terms of efficiency. + +13.12.1 Language-Defined Restrictions and Profiles + +Static Semantics + +1/2 + +The following restriction_identifiers are language defined (additional restrictions are defined in the +Specialized Needs Annexes): + +1.1/3 + +No_Implementation_Aspect_Specifications + +There are no implementation-defined aspects specified by an aspect_specification. This +restriction applies only to the current compilation or environment, not the entire partition. + +2/2 + +No_Implementation_Attributes + +There are no implementation-defined attributes. This restriction applies only to the current +compilation or environment, not the entire partition. + +2.1/3 + +No_Implementation_Identifiers + +There are no usage names that denote declarations with implementation-defined identifiers +that occur within language-defined packages or instances of language-defined generic +packages. Such identifiers can arise as follows: + +• The + +following + +language-defined packages and generic packages allow + +implementation-defined identifiers: + +• package System (see 13.7); + +• package Standard (see A.1); + +• package Ada.Command_Line (see A.15); + +• package Interfaces.C (see B.3); + +• package Interfaces.C.Strings (see B.3.1); + +• package Interfaces.C.Pointers (see B.3.2); + +• package Interfaces.COBOL (see B.4); + +• package Interfaces.Fortran (see B.5); + +• The following language-defined packages contain only implementation-defined + +identifiers: + +• package System.Machine_Code (see 13.8); + +• package Ada.Directories.Information (see A.16); + +• nested Implementation packages of the Queue containers (see A.18.28-31); + +• package Interfaces (see B.2); + +• package Ada.Interrupts.Names (see C.3.2). + +For package Standard, Standard.Long_Integer and Standard.Long_Float are considered +language-defined identifiers, but identifiers such as Standard.Short_Short_Integer are +considered implementation-defined. + +This restriction applies only to the current compilation or environment, not the entire +partition. + +2.2/3 + +2.3/3 + +2.4/3 + +2.5/3 + +2.6/3 + +2.7/3 + +2.8/3 + +2.9/3 + +2.10/3 + +2.11/3 + +2.12/3 + +2.13/3 + +2.14/3 + +2.15/3 + +2.16/3 + +2.17/3 + +2.18/3 + +13.12 Pragma Restrictions and Pragma Profile + +13 December 2012 338 + + + + + + + Ada Reference Manual — 2012 Edition + +No_Implementation_Pragmas + +There are no implementation-defined pragmas or pragma arguments. This restriction +applies only to the current compilation or environment, not the entire partition. + +No_Implementation_Units + +There is no mention in the context_clause of any implementation-defined descendants of +packages Ada, Interfaces, or System. This restriction applies only to the current compilation +or environment, not the entire partition. + +No_Obsolescent_Features + +There is no use of language features defined in Annex J. It is implementation defined +whether uses of the renamings of J.1 and of the pragmas of J.15 are detected by this +restriction. This restriction applies only to the current compilation or environment, not the +entire partition. + +The following restriction_parameter_identifiers are language defined: + +No_Dependence + +Specifies a library unit on which there are no semantic dependences. + +No_Specification_of_Aspect + +Identifies an aspect for which no aspect_specification, attribute_definition_clause, or +pragma is given. + +No_Use_Of_Attribute + +Identifies an attribute for which no attribute_reference or attribute_definition_clause is +given. + +No_Use_Of_Pragma + +Identifies a pragma which is not to be used. + +Legality Rules + +The restriction_parameter_argument of a No_Dependence restriction shall be a name; the name shall +have the form of a full expanded name of a library unit, but need not denote a unit present in the +environment. + +The restriction_parameter_argument of a No_Specification_of_Aspect restriction shall be an identifier; +this is an identifier specific to a pragma (see 2.8) and does not denote any declaration. + +The restriction_parameter_argument of a No_Use_Of_Attribute restriction shall be an identifier or one of +the reserved words Access, Delta, Digits, Mod, or Range; this is an identifier specific to a pragma. + +The restriction_parameter_argument of a No_Use_Of_Pragma restriction shall be an identifier or the +reserved word Interface; this is an identifier specific to a pragma. + +3/2 + +3.1/3 + +4/3 + +5/3 + +6/2 + +6.1/3 + +6.2/3 + +6.3/3 + +7/2 + +7.1/3 + +7.2/3 + +7.3/3 + +No compilation unit included in the partition shall depend semantically on the library unit identified by the +name of a No_Dependence restriction. + +8/3 + +Post-Compilation Rules + +The following profile_identifier is language defined: + +No_Implementation_Extensions + +Static Semantics + +For +profile_pragma_argument_associations. + +profile + +usage + +No_Implementation_Extensions, + +9/3 + +10/3 + +there + +shall + +be + +no + +11/3 + +339 13 December 2012 + +Language-Defined Restrictions and Profiles 13.12.1 + + + + + + + + + + + 12/3 + +13/3 + +1 + +1 + +2 + +3/2 + +4/1 + +5 + +6 + +7 + +8/2 + +Ada Reference Manual — 2012 Edition + +The No_Implementation_Extensions usage profile is equivalent to the following restrictions: + +No_Implementation_Aspect_Specifications, +No_Implementation_Attributes, +No_Implementation_Identifiers, +No_Implementation_Pragmas, +No_Implementation_Units. + +13.13 Streams + +A stream is a sequence of elements comprising values from possibly different types and allowing +sequential access to these values. A stream type is a type in the class whose root type is +Streams.Root_Stream_Type. A stream type may be implemented in various ways, such as an external +sequential file, an internal buffer, or a network channel. + +13.13.1 The Package Streams + +Static Semantics + +The abstract type Root_Stream_Type is the root type of the class of stream types. The types in this class +represent different kinds of streams. A new stream type is defined by extending the root type (or some +other stream type), overriding the Read and Write operations, and optionally defining additional primitive +subprograms, according to the requirements of the particular kind of stream. The predefined stream- +oriented attributes like T'Read and T'Write make dispatching calls on the Read and Write procedures of +the Root_Stream_Type. (User-defined T'Read and T'Write attributes can also make such calls, or can call +the Read and Write attributes of other types.) + +package Ada.Streams is + pragma Pure(Streams); + type Root_Stream_Type is abstract tagged limited private; + pragma Preelaborable_Initialization(Root_Stream_Type); + type Stream_Element is mod implementation-defined; + type Stream_Element_Offset is range implementation-defined; + subtype Stream_Element_Count is + Stream_Element_Offset range 0..Stream_Element_Offset'Last; + type Stream_Element_Array is + array(Stream_Element_Offset range <>) of aliased Stream_Element; + procedure Read( + Stream : in out Root_Stream_Type; + Item : out Stream_Element_Array; + Last : out Stream_Element_Offset) is abstract; + procedure Write( + Stream : in out Root_Stream_Type; + Item : in Stream_Element_Array) is abstract; +private + ... -- not specified by the language +end Ada.Streams; + +The Read operation transfers stream elements from the specified stream to fill the array Item. Elements are +transferred until Item'Length elements have been transferred, or until the end of the stream is reached. If +any elements are transferred, the index of the last stream element transferred is returned in Last. +Otherwise, Item'First - 1 is returned in Last. Last is less than Item'Last only if the end of the stream is +reached. + +9 + +The Write operation appends Item to the specified stream. + +13.12.1 Language-Defined Restrictions and Profiles + +13 December 2012 340 + + Ada Reference Manual — 2012 Edition + +Implementation Permissions + +If Stream_Element'Size is not a multiple of System.Storage_Unit, then the components of Stream_- +Element_Array need not be aliased. + +9.1/1 + +NOTES +38 See A.12.1, “The Package Streams.Stream_IO” for an example of extending type Root_Stream_Type. + +10 + +39 If the end of stream has been reached, and Item'First is Stream_Element_Offset'First, Read will raise Constraint_Error. + +11/2 + +13.13.2 Stream-Oriented Attributes + +The type-related operational attributes Write, Read, Output, and Input convert values to a stream of +elements and reconstruct values from a stream. + +1/3 + +For every subtype S of an elementary type T, the following representation attribute is defined: + +Static Semantics + +S'Stream_Size + +Denotes the number of bits read from or written to a stream by the default implementations +of S'Read and S'Write. Hence, the number of stream elements required per item of +elementary type T is: + +T'Stream_Size / Ada.Streams.Stream_Element'Size + +The value of +Stream_Element'Size. + +this attribute + +is of + +type universal_integer and + +is a multiple of + +Stream_Size may be specified for first subtypes via an attribute_definition_clause; the +expression of such a clause shall be static, nonnegative, and a multiple of +Stream_Element'Size. + +Implementation Advice + +If not specified, the value of Stream_Size for an elementary type should be the number of bits that +corresponds to the minimum number of stream elements required by the first subtype of the type, rounded +up to the nearest factor or multiple of the word size that is also a multiple of the stream element size. + +The recommended level of support for the Stream_Size attribute is: + +• A Stream_Size clause should be supported for a discrete or fixed point type T if the specified +Stream_Size is a multiple of Stream_Element'Size and is no less than the size of the first subtype +of T, and no greater than the size of the largest type of the same elementary class (signed integer, +modular integer, enumeration, ordinary fixed point, or decimal fixed point). + +For every subtype S of a specific type T, the following attributes are defined. + +S'Write + +S'Write denotes a procedure with the following specification: + +Static Semantics + +procedure S'Write( + Stream : not null access Ada.Streams.Root_Stream_Type'Class; + Item : in T) + +S'Write writes the value of Item to Stream. + +S'Read + +S'Read denotes a procedure with the following specification: + +procedure S'Read( + Stream : not null access Ada.Streams.Root_Stream_Type'Class; + Item : out T) + +S'Read reads the value of Item from Stream. + +1.1/2 + +1.2/3 + +1.3/2 + +1.4/2 + +1.5/2 + +1.6/2 + +1.7/2 + +1.8/2 + +2 + +3 + +4/2 + +5 + +6 + +7/2 + +8 + +341 13 December 2012 + +The Package Streams 13.13.1 + + + + + + + Ada Reference Manual — 2012 Edition + +8.1/3 + +For an untagged derived type, the Write (resp. Read) attribute is inherited according to the rules given in +13.1 if the attribute is specified and available for the parent type at the point where T is declared. For a +tagged derived type, these attributes are not inherited, but rather the default implementations are used. + +8.2/2 + +The default implementations of the Write and Read attributes, where available, execute as follows: + +9/3 + +9.1/3 + +9.2/3 + +10 + +11 + +12/2 + +13 + +14 + +15/2 + +16 + +18 + +19 + +For elementary types, Read reads (and Write writes) the number of stream elements implied by the +Stream_Size for the type T; the representation of those stream elements is implementation defined. For +composite types, the Write or Read attribute for each component is called in canonical order, which is last +dimension varying fastest for an array (unless the convention of the array is Fortran, in which case it is +first dimension varying fastest), and positional aggregate order for a record. Bounds are not included in the +stream if T is an array type. If T is a discriminated type, discriminants are included only if they have +defaults. If T is a tagged type, the tag is not included. For type extensions, the Write or Read attribute for +the parent type is called, followed by the Write or Read attribute of each component of the extension part, +in canonical order. For a limited type extension, if the attribute of the parent type or any progenitor type of +T is available anywhere within the immediate scope of T, and the attribute of the parent type or the type of +any of the extension components is not available at the freezing point of T, then the attribute of T shall be +directly specified. + +If T is a discriminated type and its discriminants have defaults, then S'Read first reads the discriminants +from the stream without modifying Item. S'Read then creates an object of type T constrained by these +discriminants. The value of this object is then converted to the subtype of Item and is assigned to Item. +Finally, the Read attribute for each nondiscriminant component of Item is called in canonical order as +described above. Normal default initialization and finalization take place for the created object. + +Constraint_Error is raised by the predefined Write attribute if the value of the elementary item is outside +the range of values representable using Stream_Size bits. For a signed integer type, an enumeration type, +or a fixed point type, the range is unsigned only if the integer code for the lower bound of the first subtype +is nonnegative, and a (symmetric) signed range that covers all values of the first subtype would require +more than Stream_Size bits; otherwise, the range is signed. + +For every subtype S'Class of a class-wide type T'Class: + +S'Class'Write + +S'Class'Write denotes a procedure with the following specification: + +procedure S'Class'Write( + Stream : not null access Ada.Streams.Root_Stream_Type'Class; + Item : in T'Class) + +Dispatches to the subprogram denoted by the Write attribute of the specific type identified +by the tag of Item. + +S'Class'Read S'Class'Read denotes a procedure with the following specification: + +procedure S'Class'Read( + Stream : not null access Ada.Streams.Root_Stream_Type'Class; + Item : out T'Class) + +Dispatches to the subprogram denoted by the Read attribute of the specific type identified +by the tag of Item. + +Paragraph 17 was deleted. + +For every subtype S of a specific type T, the following attributes are defined. + +S'Output + +S'Output denotes a procedure with the following specification: + +Static Semantics + +13.13.2 Stream-Oriented Attributes + +13 December 2012 342 + + + + + Ada Reference Manual — 2012 Edition + +procedure S'Output( + Stream : not null access Ada.Streams.Root_Stream_Type'Class; + Item : in T) + +S'Output writes the value of Item to Stream, including any bounds or discriminants. + +S'Input + +S'Input denotes a function with the following specification: + +function S'Input( + Stream : not null access Ada.Streams.Root_Stream_Type'Class) + return T + +S'Input reads and returns one value from Stream, using any bounds or discriminants written +by a corresponding S'Output to determine how much to read. + +For an untagged derived type, the Output (resp. Input) attribute is inherited according to the rules given in +13.1 if the attribute is specified and available for the parent type at the point where T is declared. For a +tagged derived type, these attributes are not inherited, but rather the default implementations are used. + +The default implementations of the Output and Input attributes, where available, execute as follows: +• If T is an array type, S'Output first writes the bounds, and S'Input first reads the bounds. If T has +discriminants without defaults, S'Output first writes the discriminants (using the Write attribute +of the discriminant type for each), and S'Input first reads the discriminants (using the Read +attribute of the discriminant type for each). + +• S'Output then calls S'Write to write the value of Item to the stream. S'Input then creates an object +of type T, with the bounds or (when without defaults) the discriminants, if any, taken from the +stream, passes it to S'Read, and returns the value of the object. If T has discriminants, then this +object is unconstrained if and only the discriminants have defaults. Normal default initialization +and finalization take place for this object (see 3.3.1, 7.6, and 7.6.1). + +If T is an abstract type, then S'Input is an abstract function. + +For every subtype S'Class of a class-wide type T'Class: + +S'Class'Output + +S'Class'Input + +S'Class'Output denotes a procedure with the following specification: + +procedure S'Class'Output( + Stream : not null access Ada.Streams.Root_Stream_Type'Class; + Item : in T'Class) + +First writes the external tag of Item to Stream (by calling String'Output(Stream, Tags.- +External_Tag(Item'Tag)) — see 3.9) and then dispatches to the subprogram denoted by the +Output attribute of the specific type identified by the tag. Tag_Error is raised if the tag of +Item identifies a type declared at an accessibility level deeper than that of S. + +S'Class'Input denotes a function with the following specification: + +function S'Class'Input( + Stream : not null access Ada.Streams.Root_Stream_Type'Class) + return T'Class + +First reads the external tag from Stream and determines the corresponding internal tag (by +calling Tags.Descendant_Tag(String'Input(Stream), S'Tag) which might raise Tag_Error — +see 3.9) and then dispatches to the subprogram denoted by the Input attribute of the specific +type identified by the internal tag; returns that result. If the specific type identified by the +internal tag is abstract, Constraint_Error is raised. + +20/2 + +21 + +22 + +23/2 + +24 + +25/3 + +25.1/2 + +26/3 + +27/3 + +27.1/2 + +28 + +29 + +30/2 + +31/2 + +32 + +33/2 + +34/3 + +In the default implementation of Read and Input for a composite type, for each scalar component that is a +discriminant or that has an implicit initial value, a check is made that the value returned by Read for the +component belongs to its subtype. Constraint_Error is raised if this check fails. For other scalar + +35/3 + +343 13 December 2012 + +Stream-Oriented Attributes 13.13.2 + + + + + + + + Ada Reference Manual — 2012 Edition + +components, no check is made. For each component that is of an access type, if the implementation can +detect that the value returned by Read for the component is not a value of its subtype, Constraint_Error is +raised. If the value is not a value of its subtype and this error is not detected, the component has an +abnormal value, and erroneous execution can result (see 13.9.1). In the default implementation of Read for +a composite type with defaulted discriminants, if the actual parameter of Read is constrained, a check is +made that the discriminants read from the stream are equal to those of the actual parameter. +Constraint_Error is raised if this check fails. + +It is unspecified at which point and in which order these checks are performed. In particular, if +Constraint_Error is raised due to the failure of one of these checks, it is unspecified how many stream +elements have been read from the stream. + +In the default implementation of Read and Input for a type, End_Error is raised if the end of the stream is +reached before the reading of a value of the type is completed. + +The stream-oriented attributes may be specified for any type via an attribute_definition_clause. The +subprogram name given in such a clause shall statically denote a subprogram that is not an abstract +subprogram. Furthermore, if a stream-oriented attribute is specified for an interface type by an +attribute_definition_clause, the subprogram name given in the clause shall statically denote a null +procedure. + +A stream-oriented attribute for a subtype of a specific type T is available at places where one of the +following conditions is true: + +• T is nonlimited. +• The attribute_designator is Read (resp. Write) and T is a limited record extension, and the +attribute Read (resp. Write) is available for the parent type of T and for the types of all of the +extension components. + +• T is a limited untagged derived type, and the attribute was inherited for the type. +• The attribute_designator is Input (resp. Output), and T is a limited type, and the attribute Read + +(resp. Write) is available for T. + +• The + +attribute has been +attribute_definition_clause is visible. + +specified via + +an attribute_definition_clause, + +and + +the + +A stream-oriented attribute for a subtype of a class-wide type T'Class is available at places where one of +the following conditions is true: + +• T is nonlimited; +• + +attribute + +the +specified +has +attribute_definition_clause is visible; or + +been + +via + +an attribute_definition_clause, + +and + +the + +36/2 + +37/1 + +38/3 + +39/2 + +40/2 + +41/2 + +42/2 + +43/2 + +44/2 + +45/2 + +46/2 + +47/2 + +48/2 + +• + +the corresponding attribute of T is available, provided that if T has a partial view, the +corresponding attribute is available at the end of the visible part where T is declared. + +49/2 + +50/3 + +An attribute_reference for one of the stream-oriented attributes is illegal unless the attribute is available at +the place of the attribute_reference. Furthermore, an attribute_reference for T'Input is illegal if T is an +abstract type. + +In the parameter_and_result_profiles for the default implementations of the stream-oriented attributes, +the subtype of the Item parameter is the base subtype of T if T is a scalar type, and the first subtype +otherwise. The same rule applies to the result of the Input attribute. + +13.13.2 Stream-Oriented Attributes + +13 December 2012 344 + + Ada Reference Manual — 2012 Edition + +For an attribute_definition_clause specifying one of these attributes, the subtype of the Item parameter +shall be the first subtype or the base subtype if scalar, and the first subtype if not scalar. The same rule +applies to the result of the Input function. + +A type is said to support external streaming if Read and Write attributes are provided for sending values +of such a type between active partitions, with Write marshalling the representation, and Read +unmarshalling the representation. A limited type supports external streaming only if it has available Read +and Write attributes. A type with a part that is of a nonremote access type supports external streaming only +if that access type or the type of some part that includes the access type component, has Read and Write +attributes that have been specified via an attribute_definition_clause, and that attribute_definition_clause +is visible. An anonymous access type does not support external streaming. All other types (including +remote access types, see E.2.2) support external streaming. + +51/3 + +52/3 + +If the internal tag returned by Descendant_Tag to T'Class'Input identifies a type that is not library-level +and whose tag has not been created, or does not exist in the partition at the time of the call, execution is +erroneous. + +53/2 + +Erroneous Execution + +Implementation Requirements + +For every subtype S of a language-defined nonlimited specific type T, the output generated by S'Output or +S'Write shall be readable by S'Input or S'Read, respectively. This rule applies across partitions if the +implementation conforms to the Distributed Systems Annex. + +54/1 + +If Constraint_Error is raised during a call to Read because of failure of one the above checks, the +implementation shall ensure that the discriminants of the actual parameter of Read are not modified. + +55/3 + +Implementation Permissions + +The number of calls performed by the predefined implementation of the stream-oriented attributes on the +Read and Write operations of the stream type is unspecified. An implementation may take advantage of +this permission to perform internal buffering. However, all the calls on the Read and Write operations of +the stream type needed to implement an explicit invocation of a stream-oriented attribute shall take place +before this invocation returns. An explicit invocation is one appearing explicitly in the program text, +possibly through a generic instantiation (see 12.3). + +If T is a discriminated type and its discriminants have defaults, then in two cases an execution of the +default implementation of S'Read is not required to create an anonymous object of type T: If the +discriminant values that are read in are equal to the corresponding discriminant values of Item, then no +object of type T need be created and Item may be used instead. If they are not equal and Item is a +constrained variable, then Constraint_Error may be raised at that point, before any further values are read +from the stream and before the object of type T is created. + +56/3 + +56.1/3 + +A default implementation of S'Input that calls the default implementation of S'Read may create a +constrained anonymous object with discriminants that match those in the stream. + +56.2/3 + +NOTES +40 For a definite subtype S of a type T, only T'Write and T'Read are needed to pass an arbitrary value of the subtype +through a stream. For an indefinite subtype S of a type T, T'Output and T'Input will normally be needed, since T'Write and +T'Read do not pass bounds, discriminants, or tags. + +41 User-specified attributes of S'Class are not inherited by other class-wide types descended from S. + +57 + +58 + +345 13 December 2012 + +Stream-Oriented Attributes 13.13.2 + + Ada Reference Manual — 2012 Edition + +59 + +Example of user-defined Write attribute: + +Examples + +60/2 + +1/3 + +2 + +2.1/3 + +3/3 + +4/1 + +5/3 + +6 + +7 + +7.1/2 + +7.2/3 + +8/3 + +procedure My_Write( + Stream : not null access Ada.Streams.Root_Stream_Type'Class; + Item : My_Integer'Base); +for My_Integer'Write use My_Write; + +13.14 Freezing Rules + +This subclause defines a place in the program text where each declared entity becomes “frozen.” A use of +an entity, such as a reference to it by name, or (for a type) an expression of the type, causes freezing of the +entity in some contexts, as described below. The Legality Rules forbid certain kinds of uses of an entity in +the region of text where it is frozen. + +The freezing of an entity occurs at one or more places (freezing points) in the program text where the +representation for the entity has to be fully determined. Each entity is frozen from its first freezing point to +the end of the program text (given the ordering of compilation units defined in 10.1.4). + +This subclause also defines a place in the program text where the profile of each declared callable entity +becomes frozen. A use of a callable entity causes freezing of its profile in some contexts, as described +below. At the place where the profile of a callable entity becomes frozen, the entity itself becomes frozen. + +The end of a declarative_part, protected_body, or a declaration of a library package or generic library +package, causes freezing of each entity and profile declared within it, except for incomplete types. A +noninstance body other than a renames-as-body causes freezing of each entity and profile declared before +it within the same declarative_part that is not an incomplete type; it only causes freezing of an incomplete +type if the body is within the immediate scope of the incomplete type. + +A construct that (explicitly or implicitly) references an entity can cause the freezing of the entity, as +defined by subsequent paragraphs. At the place where a construct causes freezing, each name, +expression, implicit_dereference, or range within the construct causes freezing: + +• The occurrence of a generic_instantiation causes freezing, except that a name which is a +generic actual parameter whose corresponding generic formal parameter is a formal incomplete +type (see 12.5.1) does not cause freezing. In addition, if a parameter of the instantiation is +defaulted, the default_expression or default_name for that parameter causes freezing. + +• The occurrence of an object_declaration that has no corresponding completion causes freezing. +• The declaration of a record extension causes freezing of the parent subtype. +• The declaration of a record extension, interface type, task unit, or protected unit causes freezing + +of any progenitor types specified in the declaration. + +• At the freezing point of the entity associated with an aspect_specification, any expressions or +names within the aspect_specification cause freezing. Any static expressions within an +aspect_specification also cause freezing at the end of the immediately enclosing declaration list. + +A static expression (other than within an aspect_specification) causes freezing where it occurs. An object +name or nonstatic expression causes freezing where it occurs, unless the name or expression is part of a +default_expression, a default_name, the expression of an expression function, an aspect_specification, +or a per-object expression of a component's constraint, in which case, the freezing occurs later as part of +another construct or at the freezing point of an associated entity. + +8.1/3 + +An implicit call freezes the same entities and profiles that would be frozen by an explicit call. This is true +even if the implicit call is removed via implementation permissions. + +13.13.2 Stream-Oriented Attributes + +13 December 2012 346 + + Ada Reference Manual — 2012 Edition + +If an expression is implicitly converted to a type or subtype T, then at the place where the expression +causes freezing, T is frozen. + +8.2/1 + +The following rules define which entities are frozen at the place where a construct causes freezing: + +• At the place where an expression causes freezing, the type of the expression is frozen, unless the +expression is an enumeration literal used as a discrete_choice of the array_aggregate of an +enumeration_representation_clause. + +• At the place where a function call causes freezing, the profile of the function is frozen. +Furthermore, if a parameter of the call is defaulted, the default_expression for that parameter +causes freezing. If the function call is to an expression function, the expression of the +expression function causes freezing. + +• At the place where a generic_instantiation causes freezing of a callable entity, the profile of that +entity is frozen unless the formal subprogram corresponding to the callable entity has a +parameter or result of a formal untagged incomplete type; if the callable entity is an expression +function, the expression of the expression function causes freezing. + +• At the place where a use of the Access or Unchecked_Access attribute whose prefix denotes an +expression function causes freezing, the expression of the expression function causes freezing. +• At the place where a name causes freezing, the entity denoted by the name is frozen, unless the +name is a prefix of an expanded name; at the place where an object name causes freezing, the +nominal subtype associated with the name is frozen. + +9 + +10 + +10.1/3 + +10.2/3 + +10.3/3 + +11 + +• At the place where an implicit_dereference causes freezing, the nominal subtype associated with + +11.1/1 + +the implicit_dereference is frozen. + +• At the place where a range causes freezing, the type of the range is frozen. +• At the place where an allocator causes freezing, the designated subtype of its type is frozen. If + +the type of the allocator is a derived type, then all ancestor types are also frozen. + +• At the place where a profile is frozen, each subtype of the profile is frozen. If the corresponding + +callable entity is a member of an entry family, the index subtype of the family is frozen. + +• At the place where a subtype is frozen, its type is frozen. At the place where a type is frozen, any +expressions or names within the full type definition cause freezing; the first subtype, and any +component subtypes, index subtypes, and parent subtype of the type are frozen as well. For a +specific tagged type, the corresponding class-wide type is frozen as well. For a class-wide type, +the corresponding specific type is frozen as well. + +• At the place where a specific tagged type is frozen, the primitive subprograms of the type are +in an +is + +frozen, any subprogram named + +frozen. At +the place where a +attribute_definition_clause for the type is frozen. + +type + +Legality Rules + +The explicit declaration of a primitive subprogram of a tagged type shall occur before the type is frozen +(see 3.9.2). + +A type shall be completely defined before it is frozen (see 3.11.1 and 7.3). + +The completion of a deferred constant declaration shall occur before the constant is frozen (see 7.4). + +An operational or representation item that directly specifies an aspect of an entity shall appear before the +entity is frozen (see 13.1). + +The tag (see 3.9) of a tagged type T is created at the point where T is frozen. + +Dynamic Semantics + +347 13 December 2012 + +Freezing Rules 13.14 + +12 + +13 + +14/3 + +15 + +15.1/3 + +16 + +17 + +18 + +19/1 + +20/2 + + Ada Reference Manual — 2012 Edition + +The Standard Libraries + +349 13 December 2012 + +The Standard Libraries + + Ada Reference Manual — 2012 Edition + +Annex A +(normative) +Predefined Language Environment + +This Annex contains the specifications of library units that shall be provided by every implementation. +There are three root library units: Ada, Interfaces, and System; other library units are children of these: + +1 + +2/3 + +Standard — A.1 + Ada — A.2 + + Assertions — 11.4.2 + Asynchronous_Task_Control — D.11 + Calendar — 9.6 + + Arithmetic — 9.6.1 +Formatting — 9.6.1 +Time_Zones — 9.6.1 + + Characters — A.3.1 + + Conversions — A.3.4 + Handling — A.3.2 +Latin_1 — A.3.3 + + Command_Line — A.15 + Complex_Text_IO — G.1.3 + Containers — A.18.1 + + Bounded_Doubly_Linked_Lists + — A.18.20 + + Bounded_Hashed_Maps — A.18.21 + Bounded_Hashed_Sets — A.18.23 + Bounded_Multiway_Trees — A.18.25 + Bounded_Ordered_Maps — A.18.22 + Bounded_Ordered_Sets — A.18.24 + Bounded_Priority_Queues — A.18.31 + Bounded_Synchronized_Queues + + — A.18.29 + + Bounded_Vectors — A.18.19 + Doubly_Linked_Lists — A.18.3 + Generic_Array_Sort — A.18.26 + Generic_Constrained_Array_Sort + — A.18.26 + + Generic_Sort — A.18.26 + Hashed_Maps — A.18.5 + Hashed_Sets — A.18.8 + +Indefinite_Doubly_Linked_Lists + + — A.18.12 + +Indefinite_Hashed_Maps — A.18.13 +Indefinite_Hashed_Sets — A.18.15 +Indefinite_Holders — A.18.18 +Indefinite_Multiway_Trees — A.18.17 +Indefinite_Ordered_Maps — A.18.14 +Indefinite_Ordered_Sets — A.18.16 +Indefinite_Vectors — A.18.11 + +Standard (...continued) + Ada (...continued) + + Containers (...continued) + + Multiway_Trees — A.18.10 + Ordered_Maps — A.18.6 + Ordered_Sets — A.18.9 + +Synchronized_Queue_Interfaces + + — A.18.27 + + Unbounded_Priority_Queues + + — A.18.30 + Unbounded_Synchronized_Queues + — A.18.28 + + Vectors — A.18.2 + + Decimal — F.2 + Direct_IO — A.8.4 + Directories — A.16 + + Hierarchical_File_Names — A.16.1 + +Information — A.16 + + Dispatching — D.2.1 + +EDF — D.2.6 + + Non_Preemptive — D.2.4 + Round_Robin — D.2.5 + Dynamic_Priorities — D.5.1 + +Environment_Variables — A.17 +Exceptions — 11.4.1 +Execution_Time — D.14 + Group_Budgets — D.14.2 +Interrupts — D.14.3 +Timers — D.14.1 + +Finalization — 7.6 +Float_Text_IO — A.10.9 +Float_Wide_Text_IO — A.11 +Float_Wide_Wide_Text_IO — A.11 +Integer_Text_IO — A.10.8 +Integer_Wide_Text_IO — A.11 +Integer_Wide_Wide_Text_IO — A.11 +Interrupts — C.3.2 + Names — C.3.2 +IO_Exceptions — A.13 +Iterator_Interfaces — 5.5.1 +Locales — A.19 + +351 13 December 2012 + +Predefined Language Environment A + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + Ada Reference Manual — 2012 Edition + +Standard (...continued) + Ada (...continued) + + Numerics — A.5 + + Complex_Arrays — G.3.2 + Complex_Elementary_Functions — G.1.2 + Complex_Types — G.1.1 + Discrete_Random — A.5.2 + +Elementary_Functions — A.5.1 +Float_Random — A.5.2 + + Generic_Complex_Arrays — G.3.2 + Generic_Complex_Elementary_Functions + + — G.1.2 + + Generic_Complex_Types — G.1.1 + Generic_Elementary_Functions — A.5.1 + Generic_Real_Arrays — G.3.1 + Real_Arrays — G.3.1 + + Real_Time — D.8 + +Timing_Events — D.15 + +Sequential_IO — A.8.1 +Storage_IO — A.9 +Streams — 13.13.1 + +Stream_IO — A.12.1 + +Strings — A.4.1 + Bounded — A.4.4 + +Equal_Case_Insensitive — A.4.10 + + Hash — A.4.9 + Hash_Case_Insensitive — A.4.9 +Less_Case_Insensitive — A.4.10 + +Fixed — A.4.3 + +Equal_Case_Insensitive — A.4.10 + + Hash — A.4.9 + Hash_Case_Insensitive — A.4.9 +Less_Case_Insensitive — A.4.10 + +Equal_Case_Insensitive — A.4.10 + + Hash — A.4.9 + Hash_Case_Insensitive — A.4.9 +Less_Case_Insensitive — A.4.10 + + Maps — A.4.2 + + Constants — A.4.6 + + Unbounded — A.4.5 + +Standard (...continued) + Ada (...continued) + +Strings (...continued) + Wide_Bounded — A.4.7 + + Wide_Equal_Case_Insensitive + — A.4.7 + Wide_Hash — A.4.7 + Wide_Hash_Case_Insensitive — A.4.7 + + Wide_Equal_Case_Insensitive — A.4.7 + Wide_Fixed — A.4.7 + + Wide_Equal_Case_Insensitive + — A.4.7 + Wide_Hash — A.4.7 + Wide_Hash_Case_Insensitive — A.4.7 + + Wide_Hash — A.4.7 + Wide_Hash_Case_Insensitive — A.4.7 + Wide_Maps — A.4.7 + + Wide_Constants — A.4.7 + + Wide_Unbounded — A.4.7 + + Wide_Equal_Case_Insensitive + — A.4.7 + Wide_Hash — A.4.7 + Wide_Hash_Case_Insensitive — A.4.7 + + Wide_Wide_Bounded — A.4.8 + + Wide_Wide_Equal_Case_Insensitive + + — A.4.8 + + Wide_Wide_Hash — A.4.8 + Wide_Wide_Hash_Case_Insensitive + + — A.4.8 + Wide_Wide_Equal_Case_Insensitive + + — A.4.8 + + Wide_Wide_Fixed — A.4.8 + + Wide_Wide_Equal_Case_Insensitive + + — A.4.8 + + Wide_Wide_Hash — A.4.8 + Wide_Wide_Hash_Case_Insensitive + + — A.4.8 + + Wide_Wide_Hash — A.4.8 + Wide_Wide_Hash_Case_Insensitive + — A.4.8 + +Equal_Case_Insensitive — A.4.10 + + Wide_Wide_Maps — A.4.8 + + Hash — A.4.9 + Hash_Case_Insensitive — A.4.9 +Less_Case_Insensitive — A.4.10 + + UTF_Encoding — A.4.11 + Conversions — A.4.11 +Strings — A.4.11 + + Wide_Strings — A.4.11 + Wide_Wide_Strings — A.4.11 + + Wide_Wide_Constants — A.4.8 + + Wide_Wide_Unbounded — A.4.8 + + Wide_Wide_Equal_Case_Insensitive + + — A.4.8 + + Wide_Wide_Hash — A.4.8 + Wide_Wide_Hash_Case_Insensitive + + — A.4.8 + +Synchronous_Barriers — D.10.1 +Synchronous_Task_Control — D.10 + +EDF — D.10 + +A Predefined Language Environment + +13 December 2012 352 + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + Ada Reference Manual — 2012 Edition + +Interfaces — B.2 + C — B.3 + +Pointers — B.3.2 +Strings — B.3.1 + + COBOL — B.4 +Fortran — B.5 + +System — 13.7 + Address_To_Access_Conversions — 13.7.2 + Machine_Code — 13.8 + Multiprocessors — D.16 + + Dispatching_Domains — D.16.1 + + RPC — E.5 + +Storage_Elements — 13.7.1 +Storage_Pools — 13.11 +Subpools — 13.11.4 + +Standard (...continued) + Ada (...continued) + +Tags — 3.9 + Generic_Dispatching_Constructor — 3.9 +Task_Attributes — C.7.2 +Task_Identification — C.7.1 +Task_Termination — C.7.3 +Text_IO — A.10.1 + Bounded_IO — A.10.11 + Complex_IO — G.1.3 +Editing — F.3.3 +Text_Streams — A.12.2 + Unbounded_IO — A.10.12 + Unchecked_Conversion — 13.9 + Unchecked_Deallocate_Subpool — 13.11.5 + Unchecked_Deallocation — 13.11.2 + Wide_Characters — A.3.1 + Handling — A.3.5 + Wide_Text_IO — A.11 + + Complex_IO — G.1.4 +Editing — F.3.4 +Text_Streams — A.12.3 + Wide_Bounded_IO — A.11 + Wide_Unbounded_IO — A.11 + + Wide_Wide_Characters — A.3.1 + + Handling — A.3.6 + + Wide_Wide_Text_IO — A.11 + Complex_IO — G.1.5 +Editing — F.3.5 +Text_Streams — A.12.4 + + Wide_Wide_Bounded_IO — A.11 + Wide_Wide_Unbounded_IO — A.11 + +Implementation Requirements + +The implementation shall ensure that each language-defined subprogram is reentrant in the sense that +concurrent calls on the same subprogram perform as specified, so long as all parameters that could be +passed by reference denote nonoverlapping objects. + +If a descendant of a language-defined tagged type is declared, the implementation shall ensure that each +inherited language-defined subprogram behaves as described in this International Standard. In particular, +overriding a language-defined subprogram shall not alter the effect of any inherited language-defined +subprogram. + +Implementation Permissions + +implementation may restrict + +The +implementation may restrict children of language-defined library units (other than Standard). + +the replacement of + +language-defined compilation units. The + +3/2 + +3.1/3 + +4 + +353 13 December 2012 + +Predefined Language Environment A + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + Ada Reference Manual — 2012 Edition + +A.1 The Package Standard + +1/3 + +This subclause outlines the specification of the package Standard containing all predefined identifiers in +the language. The corresponding package body is not specified by the language. + +2 + +3 + +4 + +5 + +6 + +7/1 + +8 + +9/1 + +10/1 + +11/2 + +12 + +13 + +14 + +15 + +16 + +17 + +18 + +The operators that are predefined for the types declared in the package Standard are given in comments +since they are implicitly declared. Italics are used for pseudo-names of anonymous types (such as +root_real) and for undefined information (such as implementation-defined). + +The library package Standard has the following declaration: + +Static Semantics + +package Standard is + pragma Pure(Standard); + type Boolean is (False, True); + -- The predefined relational operators for this type are as follows: + -- function "=" (Left, Right : Boolean'Base) return Boolean; + -- function "/=" (Left, Right : Boolean'Base) return Boolean; + -- function "<" (Left, Right : Boolean'Base) return Boolean; + -- function "<=" (Left, Right : Boolean'Base) return Boolean; + -- function ">" (Left, Right : Boolean'Base) return Boolean; + -- function ">=" (Left, Right : Boolean'Base) return Boolean; + -- The predefined logical operators and the predefined logical + -- negation operator are as follows: + -- function "and" (Left, Right : Boolean'Base) return Boolean'Base; + -- function "or" (Left, Right : Boolean'Base) return Boolean'Base; + -- function "xor" (Left, Right : Boolean'Base) return Boolean'Base; + -- function "not" (Right : Boolean'Base) return Boolean'Base; + -- The integer type root_integer and the + -- corresponding universal type universal_integer are predefined. + type Integer is range implementation-defined; + subtype Natural is Integer range 0 .. Integer'Last; + subtype Positive is Integer range 1 .. Integer'Last; + -- The predefined operators for type Integer are as follows: + -- function "=" (Left, Right : Integer'Base) return Boolean; + -- function "/=" (Left, Right : Integer'Base) return Boolean; + -- function "<" (Left, Right : Integer'Base) return Boolean; + -- function "<=" (Left, Right : Integer'Base) return Boolean; + -- function ">" (Left, Right : Integer'Base) return Boolean; + -- function ">=" (Left, Right : Integer'Base) return Boolean; + -- function "+" (Right : Integer'Base) return Integer'Base; + -- function "-" (Right : Integer'Base) return Integer'Base; + -- function "abs" (Right : Integer'Base) return Integer'Base; + -- function "+" (Left, Right : Integer'Base) return Integer'Base; + -- function "-" (Left, Right : Integer'Base) return Integer'Base; + -- function "*" (Left, Right : Integer'Base) return Integer'Base; + -- function "/" (Left, Right : Integer'Base) return Integer'Base; + -- function "rem" (Left, Right : Integer'Base) return Integer'Base; + -- function "mod" (Left, Right : Integer'Base) return Integer'Base; + -- function "**" (Left : Integer'Base; Right : Natural) + -- return Integer'Base; + +A.1 The Package Standard + +13 December 2012 354 + + Ada Reference Manual — 2012 Edition + + -- The specification of each operator for the type + -- root_integer, or for any additional predefined integer + -- type, is obtained by replacing Integer by the name of the type + -- in the specification of the corresponding operator of the type + -- Integer. The right operand of the exponentiation operator + -- remains as subtype Natural. + -- The floating point type root_real and the + -- corresponding universal type universal_real are predefined. + type Float is digits implementation-defined; + -- The predefined operators for this type are as follows: + -- function "=" (Left, Right : Float) return Boolean; + -- function "/=" (Left, Right : Float) return Boolean; + -- function "<" (Left, Right : Float) return Boolean; + -- function "<=" (Left, Right : Float) return Boolean; + -- function ">" (Left, Right : Float) return Boolean; + -- function ">=" (Left, Right : Float) return Boolean; + -- function "+" (Right : Float) return Float; + -- function "-" (Right : Float) return Float; + -- function "abs" (Right : Float) return Float; + -- function "+" (Left, Right : Float) return Float; + -- function "-" (Left, Right : Float) return Float; + -- function "*" (Left, Right : Float) return Float; + -- function "/" (Left, Right : Float) return Float; + -- function "**" (Left : Float; Right : Integer'Base) return Float; + -- The specification of each operator for the type root_real, or for + -- any additional predefined floating point type, is obtained by + -- replacing Float by the name of the type in the specification of the + -- corresponding operator of the type Float. + -- In addition, the following operators are predefined for the root + -- numeric types: + function "*" (Left : root_integer; Right : root_real) + return root_real; + function "*" (Left : root_real; Right : root_integer) + return root_real; + function "/" (Left : root_real; Right : root_integer) + return root_real; + -- The type universal_fixed is predefined. + -- The only multiplying operators defined between + -- fixed point types are + function "*" (Left : universal_fixed; Right : universal_fixed) + return universal_fixed; + function "/" (Left : universal_fixed; Right : universal_fixed) + return universal_fixed; + -- The type universal_access is predefined. + -- The following equality operators are predefined: + function "=" (Left, Right: universal_access) return Boolean; + function "/=" (Left, Right: universal_access) return Boolean; + +19 + +20/2 + +21 + +22 + +23 + +24 + +25 + +26 + +27 + +28 + +29 + +30 + +31 + +32 + +33 + +34 + +34.1/2 + +34.2/2 + +355 13 December 2012 + +The Package Standard A.1 + + Ada Reference Manual — 2012 Edition + +35/3 + + -- The declaration of type Character is based on the standard ISO 8859-1 character set. + + -- There are no character literals corresponding to the positions for control characters. + -- They are indicated in italics in this definition. See 3.5.2. + + type Character is + (nul, soh, stx, etx, +vt, +ht, + bs, + +lf, + + dle, dc1, dc2, dc3, + can, em, sub, esc, + +eot, enq, ack, bel, --0 (16#00#) .. 7 (16#07#) +ff, + +si, --8 (16#08#) .. 15 (16#0F#) + +so, + +cr, + +dc4, nak, syn, etb, --16 (16#10#) .. 23 (16#17#) +us, --24 (16#18#) .. 31 (16#1F#) +fs, + +gs, + +rs, + + ' ', '!', '"', '#', + '(', ')', '*', '+', + +'$', '%', '&', ''', --32 (16#20#) .. 39 (16#27#) +',', '-', '.', '/', --40 (16#28#) .. 47 (16#2F#) + + '0', '1', '2', '3', + '8', '9', ':', ';', + +'4', '5', '6', '7', --48 (16#30#) .. 55 (16#37#) +'<', '=', '>', '?', --56 (16#38#) .. 63 (16#3F#) + + '@', 'A', 'B', 'C', + 'H', 'I', 'J', 'K', + +'D', 'E', 'F', 'G', --64 (16#40#) .. 71 (16#47#) +'L', 'M', 'N', 'O', --72 (16#48#) .. 79 (16#4F#) + + 'P', 'Q', 'R', 'S', + 'X', 'Y', 'Z', '[', + +'T', 'U', 'V', 'W', --80 (16#50#) .. 87 (16#57#) +'\', ']', '^', '_', --88 (16#58#) .. 95 (16#5F#) + + '`', 'a', 'b', 'c', + 'h', 'i', 'j', 'k', + +'d', 'e', 'f', 'g', --96 (16#60#) .. 103 (16#67#) +'l', 'm', 'n', 'o', --104 (16#68#) .. 111 (16#6F#) + + 'p', 'q', 'r', 's', + 'x', 'y', 'z', '{', + +'t', 'u', 'v', 'w', --112 (16#70#) .. 119 (16#77#) +'|', '}', '~', del, --120 (16#78#) .. 127 (16#7F#) + + reserved_128, reserved_129, + reserved_132, nel, ssa, +vts, pld, + hts, htj, + +bph, nbh, +esa, +plu, ri, + +--128 (16#80#) .. 131 (16#83#) +--132 (16#84#) .. 135 (16#87#) +ss2, ss3, --136 (16#88#) .. 143 (16#8F#) + + dcs, pu1, pu2, sts, + sos, reserved_153, sci, +osc, pm, apc, + st, + +cch, mw, spa, epa, --144 (16#90#) .. 151 (16#97#) +--152 (16#98#) .. 155 (16#9B#) +csi, +--156 (16#9C#) .. 159 (16#9F#) + + ' ', '¡', '¢', '£', + '¨', '©', 'ª', '«', + ¬', soft_hyphen, '®', + +'¤', '¥', '¦', '§', --160 (16#A0#) .. 167 (16#A7#) +--168 (16#A8#) .. 171 (16#AB#) +--172 (16#AC#) .. 175 (16#AF#) + +'¯', + + '°', '±', '²', '³', + '¸', '¹', 'º', '»', + +'´', 'µ', '¶', '·', --176 (16#B0#) .. 183 (16#B7#) +'¼', '½', '¾', '¿', --184 (16#B8#) .. 191 (16#BF#) + + 'À', 'Á', 'Â', 'Ã', + 'È', 'É', 'Ê', 'Ë', + +'Ä', 'Å', 'Æ', 'Ç', --192 (16#C0#) .. 199 (16#C7#) +'Ì', 'Í', 'Î', 'Ï', --200 (16#C8#) .. 207 (16#CF#) + + 'Ð', 'Ñ', 'Ò', 'Ó', + 'Ø', 'Ù', 'Ú', 'Û', + +'Ô', 'Õ', 'Ö', '×', --208 (16#D0#) .. 215 (16#D7#) +'Ü', 'Ý', 'Þ', 'ß', --216 (16#D8#) .. 223 (16#DF#) + + 'à', 'á', 'â', 'ã', + 'è', 'é', 'ê', 'ë', + +'ä', 'å', 'æ', 'ç', --224 (16#E0#) .. 231 (16#E7#) +'ì', 'í', 'î', 'ï', --232 (16#E8#) .. 239 (16#EF#) + + 'ð', 'ñ', 'ò', 'ó', + 'ø', 'ù', 'ú', 'û', + -- The predefined operators for the type Character are the same as for + -- any enumeration type. + +'ô', 'õ', 'ö', '÷', --240 (16#F0#) .. 247 (16#F7#) +'ü', 'ý', 'þ', 'ÿ');--248 (16#F8#) .. 255 (16#FF#) + + -- The declaration of type Wide_Character is based on the standard ISO/IEC 10646:2011 BMP character + -- set. The first 256 positions have the same contents as type Character. See 3.5.2. + + type Wide_Character is (nul, soh ... Hex_0000FFFE, Hex_0000FFFF); + +36 + +36.1/3 + +A.1 The Package Standard + +13 December 2012 356 + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + Ada Reference Manual — 2012 Edition + + -- The declaration of type Wide_Wide_Character is based on the full + -- ISO/IEC 10646:2011 character set. The first 65536 positions have the + -- same contents as type Wide_Character. See 3.5.2. + + type Wide_Wide_Character is (nul, soh ... Hex_7FFFFFFE, Hex_7FFFFFFF); + for Wide_Wide_Character'Size use 32; + package ASCII is ... end ASCII; --Obsolescent; see J.5 + + -- Predefined string types: + + type String is array(Positive range <>) of Character + with Pack; + -- The predefined operators for this type are as follows: + -- function "=" (Left, Right: String) return Boolean; + -- function "/=" (Left, Right: String) return Boolean; + -- function "<" (Left, Right: String) return Boolean; + -- function "<=" (Left, Right: String) return Boolean; + -- function ">" (Left, Right: String) return Boolean; + -- function ">=" (Left, Right: String) return Boolean; + -- function "&" (Left: String; Right: String) return String; + -- function "&" (Left: Character; Right: String) return String; + -- function "&" (Left: String; Right: Character) return String; + -- function "&" (Left: Character; Right: Character) return String; + type Wide_String is array(Positive range <>) of Wide_Character + with Pack; + -- The predefined operators for this type correspond to those for String. + type Wide_Wide_String is array (Positive range <>) + of Wide_Wide_Character + with Pack; + -- The predefined operators for this type correspond to those for String. + type Duration is delta implementation-defined range implementation-defined; + -- The predefined operators for the type Duration are the same as for + -- any fixed point type. + -- The predefined exceptions: + Constraint_Error: exception; + Program_Error : exception; + Storage_Error : exception; + Tasking_Error : exception; +end Standard; + +Standard has no private part. + +In each of the types Character, Wide_Character, and Wide_Wide_Character, the character literals for the +space character (position 32) and the non-breaking space character (position 160) correspond to different +values. Unless indicated otherwise, each occurrence of the character literal ' ' in this International Standard +refers to the space character. Similarly, the character literals for hyphen (position 45) and soft hyphen +(position 173) correspond to different values. Unless indicated otherwise, each occurrence of the character +literal '–' in this International Standard refers to the hyphen character. + +Elaboration of the body of Standard has no effect. + +Dynamic Semantics + +An implementation may provide additional predefined integer types and additional predefined floating +point types. Not all of these types need have names. + +Implementation Permissions + +357 13 December 2012 + +The Package Standard A.1 + +36.2/3 + +36.3/2 + +37/3 + +38 + +39 + +40 + +41/3 + +42 + +42.1/3 + +42.2/2 + +43 + +44 + +45 + +46 + +47 + +48 + +49/2 + +50 + +51 + + + + + + Ada Reference Manual — 2012 Edition + +If an implementation provides additional named predefined integer types, then the names should end with +“Integer” as in “Long_Integer”. If an implementation provides additional named predefined floating point +types, then the names should end with “Float” as in “Long_Float”. + +Implementation Advice + +NOTES +1 Certain aspects of the predefined entities cannot be completely described in the language itself. For example, although +the enumeration type Boolean can be written showing the two enumeration literals False and True, the short-circuit +control forms cannot be expressed in the language. + +2 As explained in 8.1, “Declarative Region” and 10.1.4, “The Compilation Process”, the declarative region of the package +Standard encloses every library unit and consequently the main subprogram; the declaration of every library unit is +assumed to occur within this declarative region. Library_items are assumed to be ordered in such a way that there are no +forward semantic dependences. However, as explained in 8.3, “Visibility”, the only library units that are visible within a +given compilation unit are the library units named by all with_clauses that apply to the given unit, and moreover, within +the declarative region of a given library unit, that library unit itself. + +3 If all block_statements of a program are named, then the name of each program unit can always be written as an +expanded name starting with Standard (unless Standard is itself hidden). The name of a library unit cannot be a +homograph of a name (such as Integer) that is already declared in Standard. + +4 The exception Standard.Numeric_Error is defined in J.6. + +A.2 The Package Ada + +The following language-defined library package exists: + +Static Semantics + +package Ada is + pragma Pure(Ada); +end Ada; + +Ada serves as the parent of most of the other language-defined library units; its declaration is empty +(except for the pragma Pure). + +52 + +53 + +54 + +55 + +56 + +1 + +2 + +3 + +4 + +In the standard mode, it is illegal to compile a child of package Ada. + +Legality Rules + +A.3 Character Handling + +1/3 + +and + +This subclause presents the packages related to character processing: an empty declared pure package +Characters +and Characters.Latin_1. The package +Characters.Handling provides classification and conversion functions for Character data, and some simple +functions for dealing with Wide_Character and Wide_Wide_Character data. The child package +Characters.Latin_1 declares a set of constants initialized to values of type Character. + +child packages Characters.Handling + +A.1 The Package Standard + +13 December 2012 358 + + Ada Reference Manual — 2012 Edition + +A.3.1 The Packages Characters, Wide_Characters, and +Wide_Wide_Characters + +The library package Characters has the following declaration: + +Static Semantics + +package Ada.Characters is + pragma Pure(Characters); +end Ada.Characters; + +The library package Wide_Characters has the following declaration: + +package Ada.Wide_Characters is + pragma Pure(Wide_Characters); +end Ada.Wide_Characters; + +The library package Wide_Wide_Characters has the following declaration: + +package Ada.Wide_Wide_Characters is + pragma Pure(Wide_Wide_Characters); +end Ada.Wide_Wide_Characters; + +Implementation Advice + +If an implementation chooses to provide implementation-defined operations on Wide_Character or +Wide_String (such as collating and sorting, etc.) it should do so by providing child units of +implementation-defined operations on +it chooses +Wide_Characters. Similarly +to provide +Wide_Wide_Character or Wide_Wide_String +it should do so by providing child units of +Wide_Wide_Characters. + +if + +A.3.2 The Package Characters.Handling + +The library package Characters.Handling has the following declaration: + +Static Semantics + +with Ada.Characters.Conversions; +package Ada.Characters.Handling is + pragma Pure(Handling); +--Character classification functions + function Is_Control (Item : in Character) return Boolean; + function Is_Graphic (Item : in Character) return Boolean; + function Is_Letter (Item : in Character) return Boolean; + function Is_Lower (Item : in Character) return Boolean; + function Is_Upper (Item : in Character) return Boolean; + function Is_Basic (Item : in Character) return Boolean; + function Is_Digit (Item : in Character) return Boolean; + function Is_Decimal_Digit (Item : in Character) return Boolean + renames Is_Digit; + function Is_Hexadecimal_Digit (Item : in Character) return Boolean; + function Is_Alphanumeric (Item : in Character) return Boolean; + function Is_Special (Item : in Character) return Boolean; + function Is_Line_Terminator (Item : in Character) return Boolean; + function Is_Mark (Item : in Character) return Boolean; + function Is_Other_Format (Item : in Character) return Boolean; + function Is_Punctuation_Connector (Item : in Character) return Boolean; + function Is_Space (Item : in Character) return Boolean; + +1 + +2 + +3/2 + +4/2 + +5/2 + +6/2 + +7/3 + +1 + +2/2 + +3 + +4/3 + +359 13 December 2012 + +The Packages Characters, Wide_Characters, and Wide_Wide_Characters A.3.1 + + Ada Reference Manual — 2012 Edition + +--Conversion functions for Character and String + function To_Lower (Item : in Character) return Character; + function To_Upper (Item : in Character) return Character; + function To_Basic (Item : in Character) return Character; + function To_Lower (Item : in String) return String; + function To_Upper (Item : in String) return String; + function To_Basic (Item : in String) return String; +--Classifications of and conversions between Character and ISO 646 + subtype ISO_646 is + Character range Character'Val(0) .. Character'Val(127); + function Is_ISO_646 (Item : in Character) return Boolean; + function Is_ISO_646 (Item : in String) return Boolean; + function To_ISO_646 (Item : in Character; + Substitute : in ISO_646 := ' ') + return ISO_646; + function To_ISO_646 (Item : in String; + Substitute : in ISO_646 := ' ') + return String; +-- The functions Is_Character, Is_String, To_Character, To_String, To_Wide_Character, +-- and To_Wide_String are obsolescent; see J.14. +Paragraphs 14 through 18 were deleted. +end Ada.Characters.Handling; + +In the description below for each function that returns a Boolean result, the effect is described in terms of +the conditions under which the value True is returned. If these conditions are not met, then the function +returns False. + +Each of the following classification functions has a formal Character parameter, Item, and returns a +Boolean result. + +5 + +6 + +7 + +8 + +9 + +10 + +11 + +12 + +13/2 + +19 + +20 + +21 + +22 + +Is_Control True if Item is a control character. A control character is a character whose position is in + +one of the ranges 0..31 or 127..159. + +23 + +Is_Graphic True if Item is a graphic character. A graphic character is a character whose position is in + +one of the ranges 32..126 or 160..255. + +24 + +Is_Letter + +True if Item is a letter. A letter is a character that is in one of the ranges 'A'..'Z' or 'a'..'z', or +whose position is in one of the ranges 192..214, 216..246, or 248..255. + +25 + +Is_Lower + +True if Item is a lower-case letter. A lower-case letter is a character that is in the range +'a'..'z', or whose position is in one of the ranges 223..246 or 248..255. + +26 + +Is_Upper + +27 + +Is_Basic + +True if Item is an upper-case letter. An upper-case letter is a character that is in the range +'A'..'Z' or whose position is in one of the ranges 192..214 or 216.. 222. + +True if Item is a basic letter. A basic letter is a character that is in one of the ranges 'A'..'Z' +and 'a'..'z', or that is one of the following: 'Æ', 'æ', 'Ð', 'ð', 'Þ', 'þ', or 'ß'. + +28 + +29 + +Is_Digit + +True if Item is a decimal digit. A decimal digit is a character in the range '0'..'9'. + +Is_Decimal_Digit + +A renaming of Is_Digit. + +30 + +Is_Hexadecimal_Digit + +True if Item is a hexadecimal digit. A hexadecimal digit is a character that is either a +decimal digit or that is in one of the ranges 'A' .. 'F' or 'a' .. 'f'. + +A.3.2 The Package Characters.Handling + +13 December 2012 360 + + + + Ada Reference Manual — 2012 Edition + +Is_Alphanumeric + +True if Item is an alphanumeric character. An alphanumeric character is a character that is +either a letter or a decimal digit. + +Is_Special + +True if Item is a special graphic character. A special graphic character is a graphic +character that is not alphanumeric. + +Is_Line_Terminator + +True if Item is a character with position 10 .. 13 (Line_Feed, Line_Tabulation, Form_Feed, +Carriage_Return) or 133 (Next_Line). + +Is_Mark + +Never True (no value of type Character has categories Mark, Non-Spacing or Mark, +Spacing Combining). + +Is_Other_Format + +True if Item is a character with position 173 (Soft_Hyphen). + +Is_Punctuation_Connector + +True if Item is a character with position 95 ('_', known as Low_Line or Underscore). + +Is_Space + +True if Item is a character with position 32 (' ') or 160 (No_Break_Space). + +Each of the names To_Lower, To_Upper, and To_Basic refers to two functions: one that converts from +Character to Character, and the other that converts from String to String. The result of each Character-to- +Character function is described below, in terms of the conversion applied to Item, its formal Character +parameter. The result of each String-to-String conversion is obtained by applying to each element of the +function's String parameter the corresponding Character-to-Character conversion; the result is the null +String if the value of the formal parameter is the null String. The lower bound of the result String is 1. + +To_Lower + +To_Upper + +Returns the corresponding lower-case value for Item if Is_Upper(Item), and returns Item +otherwise. + +Returns the corresponding upper-case value for Item if Is_Lower(Item) and Item has an +upper-case form, and returns Item otherwise. The lower case letters 'ß' and 'ÿ' do not have +upper case forms. + +To_Basic + +Returns the letter corresponding to Item but with no diacritical mark, if Item is a letter but +not a basic letter; returns Item otherwise. + +The following set of functions test for membership in the ISO 646 character range, or convert between ISO +646 and Character. + +31 + +32 + +32.1/3 + +32.2/3 + +32.3/3 + +32.4/3 + +32.5/3 + +33 + +34 + +35 + +36 + +37 + +Is_ISO_646 The function whose formal parameter, Item, is of type Character returns True if Item is in + +38 + +the subtype ISO_646. + +Is_ISO_646 The function whose formal parameter, Item, is of type String returns True if + +39 + +Is_ISO_646(Item(I)) is True for each I in Item'Range. + +To_ISO_646 + +To_ISO_646 + +The function whose first formal parameter, Item, is of type Character returns Item if +Is_ISO_646(Item), and returns the Substitute ISO_646 character otherwise. + +The function whose first formal parameter, Item, is of type String returns the String whose +Range is 1..Item'Length and each of whose elements is given by To_ISO_646 of the +corresponding element in Item. + +Paragraphs 42 through 49 were deleted. + +NOTES +5 A basic letter is a letter without a diacritical mark. + +40 + +41 + +50 + +361 13 December 2012 + +The Package Characters.Handling A.3.2 + + + + + + + + Ada Reference Manual — 2012 Edition + +6 Except for the hexadecimal digits, basic letters, and ISO_646 characters, the categories identified in the classification +functions form a strict hierarchy: + +— Control characters + +— Graphic characters + +— Alphanumeric characters + +— Letters + +— Upper-case letters + +— Lower-case letters + +— Decimal digits + +— Special graphic characters + +51 + +52 + +53 + +54 + +55 + +56 + +57 + +58 + +59 + +60/3 + +7 There are certain characters which are defined to be lower case letters by ISO 10646 and are therefore allowed in +identifiers, but are not considered lower case letters by Ada.Characters.Handling. + +1 + +2 + +3 + +4 + +5 + +6 + +A.3.3 The Package Characters.Latin_1 + +The package Characters.Latin_1 declares constants for characters in ISO 8859-1. + +The library package Characters.Latin_1 has the following declaration: + +Static Semantics + +package Ada.Characters.Latin_1 is + pragma Pure(Latin_1); +-- Control characters: + NUL : constant Character := Character'Val(0); + SOH : constant Character := Character'Val(1); + STX : constant Character := Character'Val(2); + ETX : constant Character := Character'Val(3); + EOT : constant Character := Character'Val(4); + ENQ : constant Character := Character'Val(5); + ACK : constant Character := Character'Val(6); + BEL : constant Character := Character'Val(7); + BS : constant Character := Character'Val(8); + HT : constant Character := Character'Val(9); + LF : constant Character := Character'Val(10); + VT : constant Character := Character'Val(11); + FF : constant Character := Character'Val(12); + CR : constant Character := Character'Val(13); + SO : constant Character := Character'Val(14); + SI : constant Character := Character'Val(15); + DLE : constant Character := Character'Val(16); + DC1 : constant Character := Character'Val(17); + DC2 : constant Character := Character'Val(18); + DC3 : constant Character := Character'Val(19); + DC4 : constant Character := Character'Val(20); + NAK : constant Character := Character'Val(21); + SYN : constant Character := Character'Val(22); + ETB : constant Character := Character'Val(23); + CAN : constant Character := Character'Val(24); + EM : constant Character := Character'Val(25); + SUB : constant Character := Character'Val(26); + ESC : constant Character := Character'Val(27); + FS : constant Character := Character'Val(28); + GS : constant Character := Character'Val(29); + RS : constant Character := Character'Val(30); + US : constant Character := Character'Val(31); + +A.3.2 The Package Characters.Handling + +13 December 2012 362 + + + + + + + + + + + + + + Ada Reference Manual — 2012 Edition + +-- ISO 646 graphic characters: + Space : constant Character := ' '; -- Character'Val(32) + Exclamation : constant Character := '!'; -- Character'Val(33) + Quotation : constant Character := '"'; -- Character'Val(34) + Number_Sign : constant Character := '#'; -- Character'Val(35) + Dollar_Sign : constant Character := '$'; -- Character'Val(36) + Percent_Sign : constant Character := '%'; -- Character'Val(37) + Ampersand : constant Character := '&'; -- Character'Val(38) + Apostrophe : constant Character := '''; -- Character'Val(39) + Left_Parenthesis : constant Character := '('; -- Character'Val(40) + Right_Parenthesis : constant Character := ')'; -- Character'Val(41) + Asterisk : constant Character := '*'; -- Character'Val(42) + Plus_Sign : constant Character := '+'; -- Character'Val(43) + Comma : constant Character := ','; -- Character'Val(44) + Hyphen : constant Character := '-'; -- Character'Val(45) + Minus_Sign : Character renames Hyphen; + Full_Stop : constant Character := '.'; -- Character'Val(46) + Solidus : constant Character := '/'; -- Character'Val(47) + -- Decimal digits '0' though '9' are at positions 48 through 57 + Colon : constant Character := ':'; -- Character'Val(58) + Semicolon : constant Character := ';'; -- Character'Val(59) + Less_Than_Sign : constant Character := '<'; -- Character'Val(60) + Equals_Sign : constant Character := '='; -- Character'Val(61) + Greater_Than_Sign : constant Character := '>'; -- Character'Val(62) + Question : constant Character := '?'; -- Character'Val(63) + Commercial_At : constant Character := '@'; -- Character'Val(64) + -- Letters 'A' through 'Z' are at positions 65 through 90 + Left_Square_Bracket : constant Character := '['; -- Character'Val(91) + Reverse_Solidus : constant Character := '\'; -- Character'Val(92) + Right_Square_Bracket : constant Character := ']'; -- Character'Val(93) + Circumflex : constant Character := '^'; -- Character'Val(94) + Low_Line : constant Character := '_'; -- Character'Val(95) + Grave : constant Character := '`'; -- Character'Val(96) + LC_A : constant Character := 'a'; -- Character'Val(97) + LC_B : constant Character := 'b'; -- Character'Val(98) + LC_C : constant Character := 'c'; -- Character'Val(99) + LC_D : constant Character := 'd'; -- Character'Val(100) + LC_E : constant Character := 'e'; -- Character'Val(101) + LC_F : constant Character := 'f'; -- Character'Val(102) + LC_G : constant Character := 'g'; -- Character'Val(103) + LC_H : constant Character := 'h'; -- Character'Val(104) + LC_I : constant Character := 'i'; -- Character'Val(105) + LC_J : constant Character := 'j'; -- Character'Val(106) + LC_K : constant Character := 'k'; -- Character'Val(107) + LC_L : constant Character := 'l'; -- Character'Val(108) + LC_M : constant Character := 'm'; -- Character'Val(109) + LC_N : constant Character := 'n'; -- Character'Val(110) + LC_O : constant Character := 'o'; -- Character'Val(111) + LC_P : constant Character := 'p'; -- Character'Val(112) + LC_Q : constant Character := 'q'; -- Character'Val(113) + LC_R : constant Character := 'r'; -- Character'Val(114) + LC_S : constant Character := 's'; -- Character'Val(115) + LC_T : constant Character := 't'; -- Character'Val(116) + LC_U : constant Character := 'u'; -- Character'Val(117) + LC_V : constant Character := 'v'; -- Character'Val(118) + LC_W : constant Character := 'w'; -- Character'Val(119) + LC_X : constant Character := 'x'; -- Character'Val(120) + LC_Y : constant Character := 'y'; -- Character'Val(121) + LC_Z : constant Character := 'z'; -- Character'Val(122) + Left_Curly_Bracket : constant Character := '{'; -- Character'Val(123) + Vertical_Line : constant Character := '|'; -- Character'Val(124) + Right_Curly_Bracket : constant Character := '}'; -- Character'Val(125) + Tilde : constant Character := '~'; -- Character'Val(126) + DEL : constant Character := Character'Val(127); + +7 + +8 + +9 + +10 + +11 + +12 + +13 + +14 + +363 13 December 2012 + +The Package Characters.Latin_1 A.3.3 + + Ada Reference Manual — 2012 Edition + +15 + +16 + +17 + +18 + +19 + +20 + +21/3 + +-- ISO 6429 control characters: + IS4 : Character renames FS; + IS3 : Character renames GS; + IS2 : Character renames RS; + IS1 : Character renames US; + Reserved_128 : constant Character := Character'Val(128); + Reserved_129 : constant Character := Character'Val(129); + BPH : constant Character := Character'Val(130); + NBH : constant Character := Character'Val(131); + Reserved_132 : constant Character := Character'Val(132); + NEL : constant Character := Character'Val(133); + SSA : constant Character := Character'Val(134); + ESA : constant Character := Character'Val(135); + HTS : constant Character := Character'Val(136); + HTJ : constant Character := Character'Val(137); + VTS : constant Character := Character'Val(138); + PLD : constant Character := Character'Val(139); + PLU : constant Character := Character'Val(140); + RI : constant Character := Character'Val(141); + SS2 : constant Character := Character'Val(142); + SS3 : constant Character := Character'Val(143); + DCS : constant Character := Character'Val(144); + PU1 : constant Character := Character'Val(145); + PU2 : constant Character := Character'Val(146); + STS : constant Character := Character'Val(147); + CCH : constant Character := Character'Val(148); + MW : constant Character := Character'Val(149); + SPA : constant Character := Character'Val(150); + EPA : constant Character := Character'Val(151); + SOS : constant Character := Character'Val(152); + Reserved_153 : constant Character := Character'Val(153); + SCI : constant Character := Character'Val(154); + CSI : constant Character := Character'Val(155); + ST : constant Character := Character'Val(156); + OSC : constant Character := Character'Val(157); + PM : constant Character := Character'Val(158); + APC : constant Character := Character'Val(159); +-- Other graphic characters: +-- Character positions 160 (16#A0#) .. 175 (16#AF#): + No_Break_Space : constant Character := ' '; --Character'Val(160) + NBSP : Character renames No_Break_Space; + Inverted_Exclamation : constant Character := '¡'; --Character'Val(161) + Cent_Sign : constant Character := '¢'; --Character'Val(162) + Pound_Sign : constant Character := '£'; --Character'Val(163) + Currency_Sign : constant Character := '¤'; --Character'Val(164) + Yen_Sign : constant Character := '¥'; --Character'Val(165) + Broken_Bar : constant Character := '¦'; --Character'Val(166) + Section_Sign : constant Character := '§'; --Character'Val(167) + Diaeresis : constant Character := '¨'; --Character'Val(168) + Copyright_Sign : constant Character := '©'; --Character'Val(169) + Feminine_Ordinal_Indicator : constant Character := 'ª'; --Character'Val(170) + Left_Angle_Quotation : constant Character := '«'; --Character'Val(171) + Not_Sign : constant Character := '¬'; --Character'Val(172) + Soft_Hyphen : constant Character := Character'Val(173); + Registered_Trade_Mark_Sign : constant Character := '®'; --Character'Val(174) + Macron : constant Character := '¯'; --Character'Val(175) + +A.3.3 The Package Characters.Latin_1 + +13 December 2012 364 + + Ada Reference Manual — 2012 Edition + +-- Character positions 176 (16#B0#) .. 191 (16#BF#): + Degree_Sign : constant Character := '°'; --Character'Val(176) + Ring_Above : Character renames Degree_Sign; + Plus_Minus_Sign : constant Character := '±'; --Character'Val(177) + Superscript_Two : constant Character := '²'; --Character'Val(178) + Superscript_Three : constant Character := '³'; --Character'Val(179) + Acute : constant Character := '´'; --Character'Val(180) + Micro_Sign : constant Character := 'µ'; --Character'Val(181) + Pilcrow_Sign : constant Character := '¶'; --Character'Val(182) + Paragraph_Sign : Character renames Pilcrow_Sign; + Middle_Dot : constant Character := '·'; --Character'Val(183) + Cedilla : constant Character := '¸'; --Character'Val(184) + Superscript_One : constant Character := '¹'; --Character'Val(185) + Masculine_Ordinal_Indicator: constant Character := 'º'; --Character'Val(186) + Right_Angle_Quotation : constant Character := '»'; --Character'Val(187) + Fraction_One_Quarter : constant Character := '¼'; --Character'Val(188) + Fraction_One_Half : constant Character := '½'; --Character'Val(189) + Fraction_Three_Quarters : constant Character := '¾'; --Character'Val(190) + Inverted_Question : constant Character := '¿'; --Character'Val(191) +-- Character positions 192 (16#C0#) .. 207 (16#CF#): + UC_A_Grave : constant Character := 'À'; --Character'Val(192) + UC_A_Acute : constant Character := 'Á'; --Character'Val(193) + UC_A_Circumflex : constant Character := 'Â'; --Character'Val(194) + UC_A_Tilde : constant Character := 'Ã'; --Character'Val(195) + UC_A_Diaeresis : constant Character := 'Ä'; --Character'Val(196) + UC_A_Ring : constant Character := 'Å'; --Character'Val(197) + UC_AE_Diphthong : constant Character := 'Æ'; --Character'Val(198) + UC_C_Cedilla : constant Character := 'Ç'; --Character'Val(199) + UC_E_Grave : constant Character := 'È'; --Character'Val(200) + UC_E_Acute : constant Character := 'É'; --Character'Val(201) + UC_E_Circumflex : constant Character := 'Ê'; --Character'Val(202) + UC_E_Diaeresis : constant Character := 'Ë'; --Character'Val(203) + UC_I_Grave : constant Character := 'Ì'; --Character'Val(204) + UC_I_Acute : constant Character := 'Í'; --Character'Val(205) + UC_I_Circumflex : constant Character := 'Î'; --Character'Val(206) + UC_I_Diaeresis : constant Character := 'Ï'; --Character'Val(207) +-- Character positions 208 (16#D0#) .. 223 (16#DF#): + UC_Icelandic_Eth : constant Character := 'Ð'; --Character'Val(208) + UC_N_Tilde : constant Character := 'Ñ'; --Character'Val(209) + UC_O_Grave : constant Character := 'Ò'; --Character'Val(210) + UC_O_Acute : constant Character := 'Ó'; --Character'Val(211) + UC_O_Circumflex : constant Character := 'Ô'; --Character'Val(212) + UC_O_Tilde : constant Character := 'Õ'; --Character'Val(213) + UC_O_Diaeresis : constant Character := 'Ö'; --Character'Val(214) + Multiplication_Sign : constant Character := '×'; --Character'Val(215) + UC_O_Oblique_Stroke : constant Character := 'Ø'; --Character'Val(216) + UC_U_Grave : constant Character := 'Ù'; --Character'Val(217) + UC_U_Acute : constant Character := 'Ú'; --Character'Val(218) + UC_U_Circumflex : constant Character := 'Û'; --Character'Val(219) + UC_U_Diaeresis : constant Character := 'Ü'; --Character'Val(220) + UC_Y_Acute : constant Character := 'Ý'; --Character'Val(221) + UC_Icelandic_Thorn : constant Character := 'Þ'; --Character'Val(222) + LC_German_Sharp_S : constant Character := 'ß'; --Character'Val(223) + +22 + +23 + +24 + +365 13 December 2012 + +The Package Characters.Latin_1 A.3.3 + + Ada Reference Manual — 2012 Edition + +25 + +26 + +-- Character positions 224 (16#E0#) .. 239 (16#EF#): + LC_A_Grave : constant Character := 'à'; --Character'Val(224) + LC_A_Acute : constant Character := 'á'; --Character'Val(225) + LC_A_Circumflex : constant Character := 'â'; --Character'Val(226) + LC_A_Tilde : constant Character := 'ã'; --Character'Val(227) + LC_A_Diaeresis : constant Character := 'ä'; --Character'Val(228) + LC_A_Ring : constant Character := 'å'; --Character'Val(229) + LC_AE_Diphthong : constant Character := 'æ'; --Character'Val(230) + LC_C_Cedilla : constant Character := 'ç'; --Character'Val(231) + LC_E_Grave : constant Character := 'è'; --Character'Val(232) + LC_E_Acute : constant Character := 'é'; --Character'Val(233) + LC_E_Circumflex : constant Character := 'ê'; --Character'Val(234) + LC_E_Diaeresis : constant Character := 'ë'; --Character'Val(235) + LC_I_Grave : constant Character := 'ì'; --Character'Val(236) + LC_I_Acute : constant Character := 'í'; --Character'Val(237) + LC_I_Circumflex : constant Character := 'î'; --Character'Val(238) + LC_I_Diaeresis : constant Character := 'ï'; --Character'Val(239) +-- Character positions 240 (16#F0#) .. 255 (16#FF#): + LC_Icelandic_Eth : constant Character := 'ð'; --Character'Val(240) + LC_N_Tilde : constant Character := 'ñ'; --Character'Val(241) + LC_O_Grave : constant Character := 'ò'; --Character'Val(242) + LC_O_Acute : constant Character := 'ó'; --Character'Val(243) + LC_O_Circumflex : constant Character := 'ô'; --Character'Val(244) + LC_O_Tilde : constant Character := 'õ'; --Character'Val(245) + LC_O_Diaeresis : constant Character := 'ö'; --Character'Val(246) + Division_Sign : constant Character := '÷'; --Character'Val(247) + LC_O_Oblique_Stroke : constant Character := 'ø'; --Character'Val(248) + LC_U_Grave : constant Character := 'ù'; --Character'Val(249) + LC_U_Acute : constant Character := 'ú'; --Character'Val(250) + LC_U_Circumflex : constant Character := 'û'; --Character'Val(251) + LC_U_Diaeresis : constant Character := 'ü'; --Character'Val(252) + LC_Y_Acute : constant Character := 'ý'; --Character'Val(253) + LC_Icelandic_Thorn : constant Character := 'þ'; --Character'Val(254) + LC_Y_Diaeresis : constant Character := 'ÿ'; --Character'Val(255) +end Ada.Characters.Latin_1; + +27 + +An implementation may provide additional packages as children of Ada.Characters, to declare names for +the symbols of the local character set or other character sets. + +Implementation Permissions + +A.3.3 The Package Characters.Latin_1 + +13 December 2012 366 + + Ada Reference Manual — 2012 Edition + +A.3.4 The Package Characters.Conversions + +The library package Characters.Conversions has the following declaration: + +Static Semantics + +package Ada.Characters.Conversions is + pragma Pure(Conversions); + function Is_Character (Item : in Wide_Character) return Boolean; + function Is_String (Item : in Wide_String) return Boolean; + function Is_Character (Item : in Wide_Wide_Character) return Boolean; + function Is_String (Item : in Wide_Wide_String) return Boolean; + function Is_Wide_Character (Item : in Wide_Wide_Character) + return Boolean; + function Is_Wide_String (Item : in Wide_Wide_String) + return Boolean; + function To_Wide_Character (Item : in Character) return Wide_Character; + function To_Wide_String (Item : in String) return Wide_String; + function To_Wide_Wide_Character (Item : in Character) + return Wide_Wide_Character; + function To_Wide_Wide_String (Item : in String) + return Wide_Wide_String; + function To_Wide_Wide_Character (Item : in Wide_Character) + return Wide_Wide_Character; + function To_Wide_Wide_String (Item : in Wide_String) + return Wide_Wide_String; + function To_Character (Item : in Wide_Character; + Substitute : in Character := ' ') + return Character; + function To_String (Item : in Wide_String; + Substitute : in Character := ' ') + return String; + function To_Character (Item : in Wide_Wide_Character; + Substitute : in Character := ' ') + return Character; + function To_String (Item : in Wide_Wide_String; + Substitute : in Character := ' ') + return String; + function To_Wide_Character (Item : in Wide_Wide_Character; + Substitute : in Wide_Character := ' ') + return Wide_Character; + function To_Wide_String (Item : in Wide_Wide_String; + Substitute : in Wide_Character := ' ') + return Wide_String; +end Ada.Characters.Conversions; + +The functions in package Characters.Conversions test Wide_Wide_Character or Wide_Character values +for membership in Wide_Character or Character, or convert between corresponding characters of +Wide_Wide_Character, Wide_Character, and Character. + +function Is_Character (Item : in Wide_Character) return Boolean; + +Returns True if Wide_Character'Pos(Item) <= Character'Pos(Character'Last). + +function Is_Character (Item : in Wide_Wide_Character) return Boolean; + +Returns True if Wide_Wide_Character'Pos(Item) <= Character'Pos(Character'Last). + +function Is_Wide_Character (Item : in Wide_Wide_Character) return Boolean; + +Returns True if Wide_Wide_Character'Pos(Item) <= Wide_Character'Pos(Wide_Character'Last). + +1/2 + +2/2 + +3/2 + +4/2 + +5/2 + +6/2 + +7/2 + +8/2 + +9/2 + +10/2 + +11/2 + +12/2 + +13/2 + +367 13 December 2012 + +The Package Characters.Conversions A.3.4 + + Ada Reference Manual — 2012 Edition + +14/2 + +15/2 + +16/2 + +17/2 + +18/2 + +19/2 + +20/2 + +21/2 + +22/2 + +23/2 + +24/2 + +25/2 + +26/2 + +27/2 + +28/2 + +29/2 + +30/2 + +31/2 + +32/2 + +33/2 + +function Is_String (Item : in Wide_String) return Boolean; +function Is_String (Item : in Wide_Wide_String) return Boolean; + +Returns True if Is_Character(Item(I)) is True for each I in Item'Range. + +function Is_Wide_String (Item : in Wide_Wide_String) return Boolean; + +Returns True if Is_Wide_Character(Item(I)) is True for each I in Item'Range. + +function To_Character (Item : in Wide_Character; + Substitute : in Character := ' ') return Character; +function To_Character (Item : in Wide_Wide_Character; + Substitute : in Character := ' ') return Character; + +Returns the Character corresponding to Item if Is_Character(Item), and returns the Substitute +Character otherwise. + +function To_Wide_Character (Item : in Character) return Wide_Character; + +Returns the Wide_Character X such that Character'Pos(Item) = Wide_Character'Pos (X). + +function To_Wide_Character (Item : in Wide_Wide_Character; + Substitute : in Wide_Character := ' ') + return Wide_Character; + +Returns the Wide_Character corresponding to Item if Is_Wide_Character(Item), and returns the +Substitute Wide_Character otherwise. + +function To_Wide_Wide_Character (Item : in Character) + return Wide_Wide_Character; + +Returns +Wide_Wide_Character'Pos (X). + +the Wide_Wide_Character + +X + +such + +that + +Character'Pos(Item) + += + +function To_Wide_Wide_Character (Item : in Wide_Character) + return Wide_Wide_Character; + +Returns +Wide_Wide_Character'Pos (X). + +the Wide_Wide_Character X + +such + +that Wide_Character'Pos(Item) + += + +function To_String (Item : in Wide_String; + Substitute : in Character := ' ') return String; +function To_String (Item : in Wide_Wide_String; + Substitute : in Character := ' ') return String; + +Returns the String whose range is 1..Item'Length and each of whose elements is given by +To_Character of the corresponding element in Item. + +function To_Wide_String (Item : in String) return Wide_String; + +Returns the Wide_String whose range is 1..Item'Length and each of whose elements is given by +To_Wide_Character of the corresponding element in Item. + +function To_Wide_String (Item : in Wide_Wide_String; + Substitute : in Wide_Character := ' ') + return Wide_String; + +Returns the Wide_String whose range is 1..Item'Length and each of whose elements is given by +To_Wide_Character of the corresponding element in Item with the given Substitute +Wide_Character. + +A.3.4 The Package Characters.Conversions + +13 December 2012 368 + + Ada Reference Manual — 2012 Edition + +function To_Wide_Wide_String (Item : in String) return Wide_Wide_String; +function To_Wide_Wide_String (Item : in Wide_String) + return Wide_Wide_String; + +Returns the Wide_Wide_String whose range is 1..Item'Length and each of whose elements is +given by To_Wide_Wide_Character of the corresponding element in Item. + +34/2 + +35/2 + +A.3.5 The Package Wide_Characters.Handling + +The package Wide_Characters.Handling provides operations for classifying Wide_Characters and case +folding for Wide_Characters. + +1/3 + +The library package Wide_Characters.Handling has the following declaration: + +Static Semantics + +package Ada.Wide_Characters.Handling is + pragma Pure(Handling); + function Character_Set_Version return String; + function Is_Control (Item : Wide_Character) return Boolean; + function Is_Letter (Item : Wide_Character) return Boolean; + function Is_Lower (Item : Wide_Character) return Boolean; + function Is_Upper (Item : Wide_Character) return Boolean; + function Is_Digit (Item : Wide_Character) return Boolean; + function Is_Decimal_Digit (Item : Wide_Character) return Boolean + renames Is_Digit; + function Is_Hexadecimal_Digit (Item : Wide_Character) return Boolean; + function Is_Alphanumeric (Item : Wide_Character) return Boolean; + function Is_Special (Item : Wide_Character) return Boolean; + function Is_Line_Terminator (Item : Wide_Character) return Boolean; + function Is_Mark (Item : Wide_Character) return Boolean; + function Is_Other_Format (Item : Wide_Character) return Boolean; + function Is_Punctuation_Connector (Item : Wide_Character) return Boolean; + function Is_Space (Item : Wide_Character) return Boolean; + function Is_Graphic (Item : Wide_Character) return Boolean; + function To_Lower (Item : Wide_Character) return Wide_Character; + function To_Upper (Item : Wide_Character) return Wide_Character; + function To_Lower (Item : Wide_String) return Wide_String; + function To_Upper (Item : Wide_String) return Wide_String; +end Ada.Wide_Characters.Handling; + +The subprograms defined in Wide_Characters.Handling are locale independent. + +function Character_Set_Version return String; + +Returns an implementation-defined identifier that identifies the version of the character set +standard that is used for categorizing characters by the implementation. + +function Is_Control (Item : Wide_Character) return Boolean; + +Returns True if the Wide_Character designated by Item is categorized as other_control; +otherwise returns False. + +2/3 + +3/3 + +4/3 + +5/3 + +6/3 + +7/3 + +8/3 + +9/3 + +10/3 + +11/3 + +12/3 + +13/3 + +14/3 + +15/3 + +16/3 + +17/3 + +18/3 + +19/3 + +20/3 + +21/3 + +22/3 + +23/3 + +24/3 + +25/3 + +26/3 + +27/3 + +369 13 December 2012 + +The Package Characters.Conversions A.3.4 + + Ada Reference Manual — 2012 Edition + +function Is_Letter (Item : Wide_Character) return Boolean; + +Returns True if the Wide_Character designated by Item is categorized as letter_uppercase, +letter_lowercase, letter_titlecase, letter_modifier, letter_other, or number_letter; otherwise +returns False. + +function Is_Lower (Item : Wide_Character) return Boolean; + +Returns True if the Wide_Character designated by Item is categorized as letter_lowercase; +otherwise returns False. + +function Is_Upper (Item : Wide_Character) return Boolean; + +Returns True if the Wide_Character designated by Item is categorized as letter_uppercase; +otherwise returns False. + +function Is_Digit (Item : Wide_Character) return Boolean; + +Returns True if the Wide_Character designated by Item is categorized as number_decimal; +otherwise returns False. + +function Is_Hexadecimal_Digit (Item : Wide_Character) return Boolean; + +Returns True if the Wide_Character designated by Item is categorized as number_decimal, or is +in the range 'A' .. 'F' or 'a' .. 'f'; otherwise returns False. + +function Is_Alphanumeric (Item : Wide_Character) return Boolean; + +Returns True if the Wide_Character designated by Item is categorized as letter_uppercase, +letter_lowercase, +or +letter_modifier, +number_decimal; otherwise returns False. + +letter_titlecase, + +number_letter, + +letter_other, + +function Is_Special (Item : Wide_Character) return Boolean; + +Returns True if the Wide_Character designated by Item is categorized as graphic_character, but +letter_modifier, +not categorized as +letter_other, number_letter, or number_decimal; otherwise returns False. + +letter_uppercase, + +letter_lowercase, + +letter_titlecase, + +function Is_Line_Terminator (Item : Wide_Character) return Boolean; + +Returns True if the Wide_Character designated by Item is categorized as separator_line or +separator_paragraph, or if Item is a conventional line terminator character (Line_Feed, +Line_Tabulation, Form_Feed, Carriage_Return, Next_Line); otherwise returns False. + +function Is_Mark (Item : Wide_Character) return Boolean; + +Returns True if the Wide_Character designated by Item is categorized as mark_non_spacing or +mark_spacing_combining; otherwise returns False. + +function Is_Other_Format (Item : Wide_Character) return Boolean; + +Returns True if the Wide_Character designated by Item is categorized as other_format; +otherwise returns False. + +function Is_Punctuation_Connector (Item : Wide_Character) return Boolean; + +Returns True +punctuation_connector; otherwise returns False. + +the Wide_Character designated by + +if + +Item + +is + +categorized + +as + +28/3 + +29/3 + +30/3 + +31/3 + +32/3 + +33/3 + +34/3 + +35/3 + +36/3 + +37/3 + +38/3 + +39/3 + +40/3 + +41/3 + +42/3 + +43/3 + +44/3 + +45/3 + +46/3 + +47/3 + +48/3 + +49/3 + +A.3.5 The Package Wide_Characters.Handling + +13 December 2012 370 + + Ada Reference Manual — 2012 Edition + +function Is_Space (Item : Wide_Character) return Boolean; + +Returns True if the Wide_Character designated by Item is categorized as separator_space; +otherwise returns False. + +function Is_Graphic (Item : Wide_Character) return Boolean; + +Returns True if the Wide_Character designated by Item is categorized as graphic_character; +otherwise returns False. + +function To_Lower (Item : Wide_Character) return Wide_Character; + +Returns the Simple Lowercase Mapping as defined by documents referenced in the note in +Clause 1 of ISO/IEC 10646:2011 of the Wide_Character designated by Item. If the Simple +Lowercase Mapping does not exist for the Wide_Character designated by Item, then the value of +Item is returned. + +function To_Lower (Item : Wide_String) return Wide_String; + +Returns the result of applying the To_Lower conversion to each Wide_Character element of the +Wide_String designated by Item. The result is the null Wide_String if the value of the formal +parameter is the null Wide_String. The lower bound of the result Wide_String is 1. + +function To_Upper (Item : Wide_Character) return Wide_Character; + +Returns the Simple Uppercase Mapping as defined by documents referenced in the note in +Clause 1 of ISO/IEC 10646:2011 of the Wide_Character designated by Item. If the Simple +Uppercase Mapping does not exist for the Wide_Character designated by Item, then the value of +Item is returned. + +function To_Upper (Item : Wide_String) return Wide_String; + +Returns the result of applying the To_Upper conversion to each Wide_Character element of the +Wide_String designated by Item. The result is the null Wide_String if the value of the formal +parameter is the null Wide_String. The lower bound of the result Wide_String is 1. + +The string returned by Character_Set_Version should include either “10646:” or “Unicode”. + +Implementation Advice + +NOTES +8 The results returned by these functions may depend on which particular version of the 10646 standard is supported by +the implementation (see 2.1). + +9 The case insensitive equality comparison routines provided in A.4.10, “String Comparison” are also available for wide +strings (see A.4.7). + +50/3 + +51/3 + +52/3 + +53/3 + +54/3 + +55/3 + +56/3 + +57/3 + +58/3 + +59/3 + +60/3 + +61/3 + +62/3 + +63/3 + +64/3 + +A.3.6 The Package Wide_Wide_Characters.Handling + +The package Wide_Wide_Characters.Handling has the same contents as Wide_Characters.Handling +except that each occurrence of Wide_Character is replaced by Wide_Wide_Character, and each +occurrence of Wide_String is replaced by Wide_Wide_String. + +1/3 + +371 13 December 2012 + +The Package Wide_Characters.Handling A.3.5 + + Ada Reference Manual — 2012 Edition + +A.4 String Handling + +1/3 + +1 + +2 + +3 + +4/2 + +5 + +6 + +This subclause presents the specifications of the package Strings and several child packages, which +provide facilities for dealing with string data. Fixed-length, bounded-length, and unbounded-length strings +are supported, for String, Wide_String, and Wide_Wide_String. The string-handling subprograms include +searches for pattern strings and for characters in program-specified sets, translation (via a character-to- +character mapping), and transformation (replacing, inserting, overwriting, and deleting of substrings). + +A.4.1 The Package Strings + +The package Strings provides declarations common to the string handling packages. + +The library package Strings has the following declaration: + +Static Semantics + +package Ada.Strings is + pragma Pure(Strings); + Space : constant Character := ' '; + Wide_Space : constant Wide_Character := ' '; + Wide_Wide_Space : constant Wide_Wide_Character := ' '; + Length_Error, Pattern_Error, Index_Error, Translation_Error : exception; + type Alignment is (Left, Right, Center); + type Truncation is (Left, Right, Error); + type Membership is (Inside, Outside); + type Direction is (Forward, Backward); + type Trim_End is (Left, Right, Both); +end Ada.Strings; + +A.4.2 The Package Strings.Maps + +1 + +The package Strings.Maps defines the types, operations, and other entities needed for character sets and +character-to-character mappings. + +The library package Strings.Maps has the following declaration: + +Static Semantics + +package Ada.Strings.Maps is + pragma Pure(Maps); + -- Representation for a set of character values: + type Character_Set is private; + pragma Preelaborable_Initialization(Character_Set); + Null_Set : constant Character_Set; + type Character_Range is + record + Low : Character; + High : Character; + end record; + -- Represents Character range Low..High + type Character_Ranges is array (Positive range <>) of Character_Range; + function To_Set (Ranges : in Character_Ranges)return Character_Set; + function To_Set (Span : in Character_Range)return Character_Set; + function To_Ranges (Set : in Character_Set) return Character_Ranges; + function "=" (Left, Right : in Character_Set) return Boolean; + +2 + +3/2 + +4/2 + +5 + +6 + +7 + +8 + +9 + +10 + +11 + +A.4 String Handling + +13 December 2012 372 + + Ada Reference Manual — 2012 Edition + + function "not" (Right : in Character_Set) return Character_Set; + function "and" (Left, Right : in Character_Set) return Character_Set; + function "or" (Left, Right : in Character_Set) return Character_Set; + function "xor" (Left, Right : in Character_Set) return Character_Set; + function "-" (Left, Right : in Character_Set) return Character_Set; + function Is_In (Element : in Character; + Set : in Character_Set) + return Boolean; + function Is_Subset (Elements : in Character_Set; + Set : in Character_Set) + return Boolean; + function "<=" (Left : in Character_Set; + Right : in Character_Set) + return Boolean renames Is_Subset; + -- Alternative representation for a set of character values: + subtype Character_Sequence is String; + function To_Set (Sequence : in Character_Sequence)return Character_Set; + function To_Set (Singleton : in Character) return Character_Set; + function To_Sequence (Set : in Character_Set) return Character_Sequence; + -- Representation for a character to character mapping: + type Character_Mapping is private; + pragma Preelaborable_Initialization(Character_Mapping); + function Value (Map : in Character_Mapping; + Element : in Character) + return Character; + Identity : constant Character_Mapping; + function To_Mapping (From, To : in Character_Sequence) + return Character_Mapping; + function To_Domain (Map : in Character_Mapping) + return Character_Sequence; + function To_Range (Map : in Character_Mapping) + return Character_Sequence; + type Character_Mapping_Function is + access function (From : in Character) return Character; +private + ... -- not specified by the language +end Ada.Strings.Maps; + +An object of type Character_Set represents a set of characters. + +Null_Set represents the set containing no characters. + +An object Obj of type Character_Range represents the set of characters in the range Obj.Low .. Obj.High. + +An object Obj of type Character_Ranges represents the union of the sets corresponding to Obj(I) for I in +Obj'Range. + +function To_Set (Ranges : in Character_Ranges) return Character_Set; + +If Ranges'Length=0 then Null_Set is returned; otherwise, the returned value represents the set +corresponding to Ranges. + +function To_Set (Span : in Character_Range) return Character_Set; + +The returned value represents the set containing each character in Span. + +12 + +13 + +14 + +15 + +16 + +17 + +18 + +19 + +20/2 + +21 + +22 + +23 + +24 + +25 + +26 + +27 + +28 + +29 + +30 + +31 + +32/3 + +33 + +34 + +373 13 December 2012 + +The Package Strings.Maps A.4.2 + + 35 + +36/3 + +37 + +38 + +39 + +40 + +41 + +42 + +43 + +44 + +45 + +46 + +47 + +48 + +49 + +50 + +51 + +52 + +53 + +54 + +Ada Reference Manual — 2012 Edition + +function To_Ranges (Set : in Character_Set) return Character_Ranges; + +If Set = Null_Set, then an empty Character_Ranges array is returned; otherwise, the shortest +array of contiguous ranges of Character values in Set, in increasing order of Low, is returned. + +function "=" (Left, Right : in Character_Set) return Boolean; + +The function "=" returns True if Left and Right represent identical sets, and False otherwise. + +Each of the logical operators "not", "and", "or", and "xor" returns a Character_Set value that represents +the set obtained by applying the corresponding operation to the set(s) represented by the parameter(s) of +the operator. "–"(Left, Right) is equivalent to "and"(Left, "not"(Right)). + +function Is_In (Element : in Character; + Set : in Character_Set); + return Boolean; + +Is_In returns True if Element is in Set, and False otherwise. + +function Is_Subset (Elements : in Character_Set; + Set : in Character_Set) + return Boolean; + +Is_Subset returns True if Elements is a subset of Set, and False otherwise. + +subtype Character_Sequence is String; + +The Character_Sequence subtype is used to portray a set of character values and also to identify +the domain and range of a character mapping. + +function To_Set (Sequence : in Character_Sequence) return Character_Set; + +function To_Set (Singleton : in Character) return Character_Set; + +Sequence portrays the set of character values that it explicitly contains (ignoring duplicates). +Singleton portrays the set comprising a single Character. Each of the To_Set functions returns a +Character_Set value that represents the set portrayed by Sequence or Singleton. + +function To_Sequence (Set : in Character_Set) return Character_Sequence; + +The function To_Sequence returns a Character_Sequence value containing each of the characters +in the set represented by Set, in ascending order with no duplicates. + +type Character_Mapping is private; + +An object of type Character_Mapping represents a Character-to-Character mapping. + +function Value (Map : in Character_Mapping; + Element : in Character) + return Character; + +The function Value returns the Character value to which Element maps with respect to the +mapping represented by Map. + +A character C matches a pattern character P with respect to a given Character_Mapping value Map if +Value(Map, C) = P. A string S matches a pattern string P with respect to a given Character_Mapping if +their lengths are the same and if each character in S matches its corresponding character in the pattern +string P. + +55 + +String handling subprograms that deal with character mappings have parameters whose type is +Character_Mapping. + +A.4.2 The Package Strings.Maps + +13 December 2012 374 + + + Ada Reference Manual — 2012 Edition + +Identity : constant Character_Mapping; + +Identity maps each Character to itself. + +function To_Mapping (From, To : in Character_Sequence) + return Character_Mapping; + +To_Mapping produces a Character_Mapping such that each element of From maps to the +corresponding element of To, and each other character maps to itself. If From'Length /= +To'Length, or if some character is repeated in From, then Translation_Error is propagated. + +function To_Domain (Map : in Character_Mapping) return Character_Sequence; + +To_Domain returns the shortest Character_Sequence value D such that each character not in D +maps to itself, and such that the characters in D are in ascending order. The lower bound of D is +1. + +function To_Range (Map : in Character_Mapping) return Character_Sequence; + +To_Range returns the Character_Sequence value R, such that if D = To_Domain(Map), then R +has the same bounds as D, and D(I) maps to R(I) for each I in D'Range. + +An object F of type Character_Mapping_Function maps a Character value C to the Character value +F.all(C), which is said to match C with respect to mapping function F. + +NOTES +10 Character_Mapping and Character_Mapping_Function are used both for character equivalence mappings in the search +subprograms (such as for case insensitivity) and as transformational mappings in the Translate subprograms. + +11 To_Domain(Identity) and To_Range(Identity) each returns the null string. + +To_Mapping("ABCD", "ZZAB") returns a Character_Mapping that maps 'A' and 'B' to 'Z', 'C' to 'A', 'D' to +'B', and each other Character to itself. + +Examples + +A.4.3 Fixed-Length String Handling + +The language-defined package Strings.Fixed provides string-handling subprograms for fixed-length +strings; that is, for values of type Standard.String. Several of these subprograms are procedures that +modify the contents of a String that is passed as an out or an in out parameter; each has additional +parameters to control the effect when the logical length of the result differs from the parameter's length. + +For each function that returns a String, the lower bound of the returned value is 1. + +The basic model embodied in the package is that a fixed-length string comprises significant characters and +possibly padding (with space characters) on either or both ends. When a shorter string is copied to a longer +string, padding is inserted, and when a longer string is copied to a shorter one, padding is stripped. The +Move procedure in Strings.Fixed, which takes a String as an out parameter, allows the programmer to +control these effects. Similar control is provided by the string transformation procedures. + +Static Semantics + +The library package Strings.Fixed has the following declaration: + +with Ada.Strings.Maps; +package Ada.Strings.Fixed is + pragma Preelaborate(Fixed); +-- "Copy" procedure for strings of possibly different lengths + +56 + +57 + +58 + +59 + +60 + +61 + +62 + +63/1 + +64 + +65 + +66 + +67 + +1 + +2 + +3 + +4 + +5 + +6 + +375 13 December 2012 + +The Package Strings.Maps A.4.2 + + Ada Reference Manual — 2012 Edition + +7 + +8 + +8.1/2 + +8.2/2 + +9 + +10 + +10.1/2 + +11 + +11.1/2 + +12 + +13 + +14 + +15 + + procedure Move (Source : in String; + Target : out String; + Drop : in Truncation := Error; + Justify : in Alignment := Left; + Pad : in Character := Space); +-- Search subprograms + function Index (Source : in String; + Pattern : in String; + From : in Positive; + Going : in Direction := Forward; + Mapping : in Maps.Character_Mapping := Maps.Identity) + return Natural; + function Index (Source : in String; + Pattern : in String; + From : in Positive; + Going : in Direction := Forward; + Mapping : in Maps.Character_Mapping_Function) + return Natural; + function Index (Source : in String; + Pattern : in String; + Going : in Direction := Forward; + Mapping : in Maps.Character_Mapping + := Maps.Identity) + return Natural; + function Index (Source : in String; + Pattern : in String; + Going : in Direction := Forward; + Mapping : in Maps.Character_Mapping_Function) + return Natural; + function Index (Source : in String; + Set : in Maps.Character_Set; + From : in Positive; + Test : in Membership := Inside; + Going : in Direction := Forward) + return Natural; + function Index (Source : in String; + Set : in Maps.Character_Set; + Test : in Membership := Inside; + Going : in Direction := Forward) + return Natural; + function Index_Non_Blank (Source : in String; + From : in Positive; + Going : in Direction := Forward) + return Natural; + function Index_Non_Blank (Source : in String; + Going : in Direction := Forward) + return Natural; + function Count (Source : in String; + Pattern : in String; + Mapping : in Maps.Character_Mapping + := Maps.Identity) + return Natural; + function Count (Source : in String; + Pattern : in String; + Mapping : in Maps.Character_Mapping_Function) + return Natural; + function Count (Source : in String; + Set : in Maps.Character_Set) + return Natural; + +A.4.3 Fixed-Length String Handling + +13 December 2012 376 + + Ada Reference Manual — 2012 Edition + + procedure Find_Token (Source : in String; + Set : in Maps.Character_Set; + From : in Positive; + Test : in Membership; + First : out Positive; + Last : out Natural); + procedure Find_Token (Source : in String; + Set : in Maps.Character_Set; + Test : in Membership; + First : out Positive; + Last : out Natural); +-- String translation subprograms + function Translate (Source : in String; + Mapping : in Maps.Character_Mapping) + return String; + procedure Translate (Source : in out String; + Mapping : in Maps.Character_Mapping); + function Translate (Source : in String; + Mapping : in Maps.Character_Mapping_Function) + return String; + procedure Translate (Source : in out String; + Mapping : in Maps.Character_Mapping_Function); +-- String transformation subprograms + function Replace_Slice (Source : in String; + Low : in Positive; + High : in Natural; + By : in String) + return String; + procedure Replace_Slice (Source : in out String; + Low : in Positive; + High : in Natural; + By : in String; + Drop : in Truncation := Error; + Justify : in Alignment := Left; + Pad : in Character := Space); + function Insert (Source : in String; + Before : in Positive; + New_Item : in String) + return String; + procedure Insert (Source : in out String; + Before : in Positive; + New_Item : in String; + Drop : in Truncation := Error); + function Overwrite (Source : in String; + Position : in Positive; + New_Item : in String) + return String; + procedure Overwrite (Source : in out String; + Position : in Positive; + New_Item : in String; + Drop : in Truncation := Right); + function Delete (Source : in String; + From : in Positive; + Through : in Natural) + return String; + procedure Delete (Source : in out String; + From : in Positive; + Through : in Natural; + Justify : in Alignment := Left; + Pad : in Character := Space); + +15.1/3 + +16 + +17 + +18 + +19 + +20 + +21 + +22 + +23 + +24 + +25 + +26 + +27 + +28 + +29 + +30 + +377 13 December 2012 + +Fixed-Length String Handling A.4.3 + + 31 + +32 + +33 + +34 + +35 + +36 + +37 + +38 + +39 + +40 + +41 + +42 + +43 + +44 + +45/3 + +46 + +47 + +48 + +49 + +Ada Reference Manual — 2012 Edition + + --String selector subprograms + function Trim (Source : in String; + Side : in Trim_End) + return String; + procedure Trim (Source : in out String; + Side : in Trim_End; + Justify : in Alignment := Left; + Pad : in Character := Space); + function Trim (Source : in String; + Left : in Maps.Character_Set; + Right : in Maps.Character_Set) + return String; + procedure Trim (Source : in out String; + Left : in Maps.Character_Set; + Right : in Maps.Character_Set; + Justify : in Alignment := Strings.Left; + Pad : in Character := Space); + function Head (Source : in String; + Count : in Natural; + Pad : in Character := Space) + return String; + procedure Head (Source : in out String; + Count : in Natural; + Justify : in Alignment := Left; + Pad : in Character := Space); + function Tail (Source : in String; + Count : in Natural; + Pad : in Character := Space) + return String; + procedure Tail (Source : in out String; + Count : in Natural; + Justify : in Alignment := Left; + Pad : in Character := Space); +--String constructor functions + function "*" (Left : in Natural; + Right : in Character) return String; + function "*" (Left : in Natural; + Right : in String) return String; +end Ada.Strings.Fixed; + +The effects of the above subprograms are as follows. + +procedure Move (Source : in String; + Target : out String; + Drop : in Truncation := Error; + Justify : in Alignment := Left; + Pad : in Character := Space); + +The Move procedure copies characters from Source to Target. If Source has the same length as +Target, then the effect is to assign Source to Target. If Source is shorter than Target, then: +• If Justify=Left, then Source is copied into the first Source'Length characters of Target. +• If Justify=Right, then Source is copied into the last Source'Length characters of + +Target. + +• If Justify=Center, then Source is copied into the middle Source'Length characters of +Target. In this case, if the difference in length between Target and Source is odd, then +the extra Pad character is on the right. + +• Pad is copied to each Target character not otherwise assigned. + +A.4.3 Fixed-Length String Handling + +13 December 2012 378 + + Ada Reference Manual — 2012 Edition + +If Source is longer than Target, then the effect is based on Drop. + +• If Drop=Left, then the rightmost Target'Length characters of Source are copied into + +Target. + +• If Drop=Right, then the leftmost Target'Length characters of Source are copied into + +Target. + +• If Drop=Error, then the effect depends on the value of the Justify parameter and also + +on whether any characters in Source other than Pad would fail to be copied: + +• If Justify=Left, and if each of the rightmost Source'Length-Target'Length +characters in Source is Pad, then the leftmost Target'Length characters of Source +are copied to Target. + +• If Justify=Right, and if each of the leftmost Source'Length-Target'Length +characters in Source is Pad, then the rightmost Target'Length characters of Source +are copied to Target. + +• Otherwise, Length_Error is propagated. + +function Index (Source : in String; + Pattern : in String; + From : in Positive; + Going : in Direction := Forward; + Mapping : in Maps.Character_Mapping := Maps.Identity) + return Natural; + +function Index (Source : in String; + Pattern : in String; + From : in Positive; + Going : in Direction := Forward; + Mapping : in Maps.Character_Mapping_Function) + return Natural; + +Each Index function searches, starting from From, for a slice of Source, with length +Pattern'Length, that matches Pattern with respect to Mapping; the parameter Going indicates the +direction of the lookup. If Source is the null string, Index returns 0; otherwise, if From is not in +Source'Range, then Index_Error is propagated. If Going = Forward, then Index returns the +smallest index I which is greater than or equal to From such that the slice of Source starting at I +matches Pattern. If Going = Backward, then Index returns the largest index I such that the slice +of Source starting at I matches Pattern and has an upper bound less than or equal to From. If +there is no such slice, then 0 is returned. If Pattern is the null string, then Pattern_Error is +propagated. + +function Index (Source : in String; + Pattern : in String; + Going : in Direction := Forward; + Mapping : in Maps.Character_Mapping + := Maps.Identity) + return Natural; + +function Index (Source : in String; + Pattern : in String; + Going : in Direction := Forward; + Mapping : in Maps.Character_Mapping_Function) + return Natural; + +If Going = Forward, returns + + Index (Source, Pattern, Source'First, Forward, Mapping); + +otherwise, returns + +50 + +51 + +52 + +53 + +54 + +55 + +56 + +56.1/2 + +56.2/3 + +57 + +58/2 + +58.1/2 + +58.2/3 + +379 13 December 2012 + +Fixed-Length String Handling A.4.3 + + + + 58.3/2 + +58.4/2 + +58.5/3 + +59 + +60/2 + +60.1/2 + +60.2/3 + +60.3/2 + +60.4/2 + +Ada Reference Manual — 2012 Edition + + Index (Source, Pattern, Source'Last, Backward, Mapping); + +function Index (Source : in String; + Set : in Maps.Character_Set; + From : in Positive; + Test : in Membership := Inside; + Going : in Direction := Forward) + return Natural; + +Index searches for the first or last occurrence of any of a set of characters (when Test=Inside), or +any of the complement of a set of characters (when Test=Outside). If Source is the null string, +Index returns 0; otherwise, if From is not in Source'Range, then Index_Error is propagated. +Otherwise, it returns the smallest index I >= From (if Going=Forward) or the largest index I <= +From (if Going=Backward) such that Source(I) satisfies the Test condition with respect to Set; it +returns 0 if there is no such Character in Source. + +function Index (Source : in String; + Set : in Maps.Character_Set; + Test : in Membership := Inside; + Going : in Direction := Forward) + return Natural; + +If Going = Forward, returns + + Index (Source, Set, Source'First, Test, Forward); + +otherwise, returns + + Index (Source, Set, Source'Last, Test, Backward); + +function Index_Non_Blank (Source : in String; + From : in Positive; + Going : in Direction := Forward) + return Natural; + +60.5/2 + +Returns Index (Source, Maps.To_Set(Space), From, Outside, Going); + +61 + +62 + +63 + +64 + +65 + +66 + +function Index_Non_Blank (Source : in String; + Going : in Direction := Forward) + return Natural; + +Returns Index(Source, Maps.To_Set(Space), Outside, Going) + +function Count (Source : in String; + Pattern : in String; + Mapping : in Maps.Character_Mapping + := Maps.Identity) + return Natural; + +function Count (Source : in String; + Pattern : in String; + Mapping : in Maps.Character_Mapping_Function) + return Natural; + +Returns the maximum number of nonoverlapping slices of Source that match Pattern with +respect to Mapping. If Pattern is the null string then Pattern_Error is propagated. + +function Count (Source : in String; + Set : in Maps.Character_Set) + return Natural; + +Returns the number of occurrences in Source of characters that are in Set. + +A.4.3 Fixed-Length String Handling + +13 December 2012 380 + + + Ada Reference Manual — 2012 Edition + +procedure Find_Token (Source : in String; + Set : in Maps.Character_Set; + From : in Positive; + Test : in Membership; + First : out Positive; + Last : out Natural); + +If Source is not the null string and From is not in Source'Range, then Index_Error is raised. +Otherwise, First is set to the index of the first character in Source(From .. Source'Last) that +satisfies the Test condition. Last is set to the largest index such that all characters in Source(First +.. Last) satisfy the Test condition. If no characters in Source(From .. Source'Last) satisfy the Test +condition, First is set to From, and Last is set to 0. + +procedure Find_Token (Source : in String; + Set : in Maps.Character_Set; + Test : in Membership; + First : out Positive; + Last : out Natural); + +Equivalent to Find_Token (Source, Set, Source'First, Test, First, Last). + +function Translate (Source : in String; + Mapping : in Maps.Character_Mapping) + return String; + +function Translate (Source : in String; + Mapping : in Maps.Character_Mapping_Function) + return String; + +Returns the string S whose length is Source'Length and such that S(I) is the character to which +Mapping maps the corresponding element of Source, for I in 1..Source'Length. + +procedure Translate (Source : in out String; + Mapping : in Maps.Character_Mapping); + +procedure Translate (Source : in out String; + Mapping : in Maps.Character_Mapping_Function); + +Equivalent to Source := Translate(Source, Mapping). + +function Replace_Slice (Source : in String; + Low : in Positive; + High : in Natural; + By : in String) + return String; + +66.1/3 + +66.2/3 + +67 + +68/3 + +69 + +70 + +71 + +72 + +73 + +If Low > Source'Last+1, or High < Source'First–1, then Index_Error is propagated. Otherwise: +• If High >= Low, then the returned string comprises Source(Source'First..Low–1) & By + +74/1 + +74.1/1 + +& Source(High+1..Source'Last), but with lower bound 1. + +• If High < Low, +New_Item=>By). + +then + +the returned string + +is Insert(Source, Before=>Low, + +74.2/1 + +procedure Replace_Slice (Source : in out String; + Low : in Positive; + High : in Natural; + By : in String; + Drop : in Truncation := Error; + Justify : in Alignment := Left; + Pad : in Character := Space); + +75 + +Equivalent to Move(Replace_Slice(Source, Low, High, By), Source, Drop, Justify, Pad). + +76 + +381 13 December 2012 + +Fixed-Length String Handling A.4.3 + + + + Ada Reference Manual — 2012 Edition + +function Insert (Source : in String; + Before : in Positive; + New_Item : in String) + return String; + +Propagates Index_Error if Before is not in Source'First .. Source'Last+1; otherwise, returns +Source(Source'First..Before–1) & New_Item & Source(Before..Source'Last), but with lower +bound 1. + +procedure Insert (Source : in out String; + Before : in Positive; + New_Item : in String; + Drop : in Truncation := Error); + +Equivalent to Move(Insert(Source, Before, New_Item), Source, Drop). + +function Overwrite (Source : in String; + Position : in Positive; + New_Item : in String) + return String; + +Propagates Index_Error if Position is not in Source'First .. Source'Last+1; otherwise, returns the +string obtained from Source by consecutively replacing characters starting at Position with +corresponding characters from New_Item. If the end of Source is reached before the characters +in New_Item are exhausted, the remaining characters from New_Item are appended to the string. + +procedure Overwrite (Source : in out String; + Position : in Positive; + New_Item : in String; + Drop : in Truncation := Right); + +Equivalent to Move(Overwrite(Source, Position, New_Item), Source, Drop). + +function Delete (Source : in String; + From : in Positive; + Through : in Natural) + return String; + +If From <= Through, the returned string is Replace_Slice(Source, From, Through, ""); +otherwise, it is Source with lower bound 1. + +procedure Delete (Source : in out String; + From : in Positive; + Through : in Natural; + Justify : in Alignment := Left; + Pad : in Character := Space); + +Equivalent to Move(Delete(Source, From, Through), Source, Justify => Justify, Pad => Pad). + +function Trim (Source : in String; + Side : in Trim_End) + return String; + +Returns the string obtained by removing from Source all leading Space characters (if Side = +Left), all trailing Space characters (if Side = Right), or all leading and trailing Space characters +(if Side = Both). + +procedure Trim (Source : in out String; + Side : in Trim_End; + Justify : in Alignment := Left; + Pad : in Character := Space); + +Equivalent to Move(Trim(Source, Side), Source, Justify=>Justify, Pad=>Pad). + +77 + +78/3 + +79 + +80 + +81 + +82/3 + +83 + +84 + +85 + +86/3 + +87 + +88 + +89 + +90 + +91 + +92 + +A.4.3 Fixed-Length String Handling + +13 December 2012 382 + + Ada Reference Manual — 2012 Edition + +function Trim (Source : in String; + Left : in Maps.Character_Set; + Right : in Maps.Character_Set) + return String; + +Returns the string obtained by removing from Source all leading characters in Left and all +trailing characters in Right. + +procedure Trim (Source : in out String; + Left : in Maps.Character_Set; + Right : in Maps.Character_Set; + Justify : in Alignment := Strings.Left; + Pad : in Character := Space); + +Equivalent to Move(Trim(Source, Left, Right), Source, Justify => Justify, Pad=>Pad). + +function Head (Source : in String; + Count : in Natural; + Pad : in Character := Space) + return String; + +Returns a string of length Count. If Count <= Source'Length, the string comprises the first Count +characters of Source. Otherwise, its contents are Source concatenated with Count–Source'Length +Pad characters. + +procedure Head (Source : in out String; + Count : in Natural; + Justify : in Alignment := Left; + Pad : in Character := Space); + +93 + +94 + +95 + +96 + +97 + +98/3 + +99 + +Equivalent +Pad=>Pad). + +to Move(Head(Source, Count, Pad), Source, Drop=>Error, Justify=>Justify, + +100 + +function Tail (Source : in String; + Count : in Natural; + Pad : in Character := Space) + return String; + +Returns a string of length Count. If Count <= Source'Length, the string comprises the last Count +characters of Source. Otherwise, its contents are Count-Source'Length Pad characters +concatenated with Source. + +procedure Tail (Source : in out String; + Count : in Natural; + Justify : in Alignment := Left; + Pad : in Character := Space); + +101 + +102/3 + +103 + +Equivalent +Pad=>Pad). + +to Move(Tail(Source, Count, Pad), Source, Drop=>Error, Justify=>Justify, + +104 + +function "*" (Left : in Natural; + Right : in Character) return String; + +function "*" (Left : in Natural; + Right : in String) return String; + +These functions replicate a character or string a specified number of times. The first function +returns a string whose length is Left and each of whose elements is Right. The second function +returns a string whose length is Left*Right'Length and whose value is the null string if Left = 0 +and otherwise is (Left–1)*Right & Right with lower bound 1. + +105 + +106/1 + +383 13 December 2012 + +Fixed-Length String Handling A.4.3 + + + Ada Reference Manual — 2012 Edition + +107/3 + +108 + +109 + +NOTES +12 In the Index and Count functions taking Pattern and Mapping parameters, the actual String parameter passed to Pattern +should comprise characters occurring as target characters of the mapping. Otherwise, the pattern will not match. + +13 In the Insert subprograms, inserting at the end of a string is obtained by passing Source'Last+1 as the Before +parameter. + +14 If a null Character_Mapping_Function is passed to any of the string handling subprograms, Constraint_Error is +propagated. + +1 + +2 + +3 + +4 + +5 + +6 + +7 + +8 + +9 + +10 + +11 + +12 + +12.1/2 + +13 + +14 + +15 + +A.4.4 Bounded-Length String Handling + +The language-defined package Strings.Bounded provides a generic package each of whose instances yields +a private type Bounded_String and a set of operations. An object of a particular Bounded_String type +represents a String whose low bound is 1 and whose length can vary conceptually between 0 and a +maximum size established at the generic instantiation. The subprograms for fixed-length string handling +are either overloaded directly for Bounded_String, or are modified as needed to reflect the variability in +length. Additionally, since the Bounded_String type is private, appropriate constructor and selector +operations are provided. + +The library package Strings.Bounded has the following declaration: + +Static Semantics + +with Ada.Strings.Maps; +package Ada.Strings.Bounded is + pragma Preelaborate(Bounded); + generic + Max : Positive; -- Maximum length of a Bounded_String + package Generic_Bounded_Length is + Max_Length : constant Positive := Max; + type Bounded_String is private; + Null_Bounded_String : constant Bounded_String; + subtype Length_Range is Natural range 0 .. Max_Length; + function Length (Source : in Bounded_String) return Length_Range; + -- Conversion, Concatenation, and Selection functions + function To_Bounded_String (Source : in String; + Drop : in Truncation := Error) + return Bounded_String; + function To_String (Source : in Bounded_String) return String; + procedure Set_Bounded_String + (Target : out Bounded_String; + Source : in String; + Drop : in Truncation := Error); + function Append (Left, Right : in Bounded_String; + Drop : in Truncation := Error) + return Bounded_String; + function Append (Left : in Bounded_String; + Right : in String; + Drop : in Truncation := Error) + return Bounded_String; + function Append (Left : in String; + Right : in Bounded_String; + Drop : in Truncation := Error) + return Bounded_String; + +A.4.3 Fixed-Length String Handling + +13 December 2012 384 + + Ada Reference Manual — 2012 Edition + + function Append (Left : in Bounded_String; + Right : in Character; + Drop : in Truncation := Error) + return Bounded_String; + function Append (Left : in Character; + Right : in Bounded_String; + Drop : in Truncation := Error) + return Bounded_String; + procedure Append (Source : in out Bounded_String; + New_Item : in Bounded_String; + Drop : in Truncation := Error); + procedure Append (Source : in out Bounded_String; + New_Item : in String; + Drop : in Truncation := Error); + procedure Append (Source : in out Bounded_String; + New_Item : in Character; + Drop : in Truncation := Error); + function "&" (Left, Right : in Bounded_String) + return Bounded_String; + function "&" (Left : in Bounded_String; Right : in String) + return Bounded_String; + function "&" (Left : in String; Right : in Bounded_String) + return Bounded_String; + function "&" (Left : in Bounded_String; Right : in Character) + return Bounded_String; + function "&" (Left : in Character; Right : in Bounded_String) + return Bounded_String; + function Element (Source : in Bounded_String; + Index : in Positive) + return Character; + procedure Replace_Element (Source : in out Bounded_String; + Index : in Positive; + By : in Character); + function Slice (Source : in Bounded_String; + Low : in Positive; + High : in Natural) + return String; + function Bounded_Slice + (Source : in Bounded_String; + Low : in Positive; + High : in Natural) + return Bounded_String; + procedure Bounded_Slice + (Source : in Bounded_String; + Target : out Bounded_String; + Low : in Positive; + High : in Natural); + function "=" (Left, Right : in Bounded_String) return Boolean; + function "=" (Left : in Bounded_String; Right : in String) + return Boolean; + function "=" (Left : in String; Right : in Bounded_String) + return Boolean; + function "<" (Left, Right : in Bounded_String) return Boolean; + function "<" (Left : in Bounded_String; Right : in String) + return Boolean; + function "<" (Left : in String; Right : in Bounded_String) + return Boolean; + +16 + +17 + +18 + +19 + +20 + +21 + +22 + +23 + +24 + +25 + +26 + +27 + +28 + +28.1/2 + +28.2/2 + +29 + +30 + +31 + +32 + +33 + +385 13 December 2012 + +Bounded-Length String Handling A.4.4 + + Ada Reference Manual — 2012 Edition + +34 + +35 + +36 + +37 + +38 + +39 + +40 + +41 + +42 + +43/2 + +43.1/2 + +43.2/2 + +44 + +45 + +45.1/2 + +46 + +46.1/2 + +47 + + function "<=" (Left, Right : in Bounded_String) return Boolean; + function "<=" (Left : in Bounded_String; Right : in String) + return Boolean; + function "<=" (Left : in String; Right : in Bounded_String) + return Boolean; + function ">" (Left, Right : in Bounded_String) return Boolean; + function ">" (Left : in Bounded_String; Right : in String) + return Boolean; + function ">" (Left : in String; Right : in Bounded_String) + return Boolean; + function ">=" (Left, Right : in Bounded_String) return Boolean; + function ">=" (Left : in Bounded_String; Right : in String) + return Boolean; + function ">=" (Left : in String; Right : in Bounded_String) + return Boolean; + -- Search subprograms + function Index (Source : in Bounded_String; + Pattern : in String; + From : in Positive; + Going : in Direction := Forward; + Mapping : in Maps.Character_Mapping := Maps.Identity) + return Natural; + function Index (Source : in Bounded_String; + Pattern : in String; + From : in Positive; + Going : in Direction := Forward; + Mapping : in Maps.Character_Mapping_Function) + return Natural; + function Index (Source : in Bounded_String; + Pattern : in String; + Going : in Direction := Forward; + Mapping : in Maps.Character_Mapping + := Maps.Identity) + return Natural; + function Index (Source : in Bounded_String; + Pattern : in String; + Going : in Direction := Forward; + Mapping : in Maps.Character_Mapping_Function) + return Natural; + function Index (Source : in Bounded_String; + Set : in Maps.Character_Set; + From : in Positive; + Test : in Membership := Inside; + Going : in Direction := Forward) + return Natural; + function Index (Source : in Bounded_String; + Set : in Maps.Character_Set; + Test : in Membership := Inside; + Going : in Direction := Forward) + return Natural; + function Index_Non_Blank (Source : in Bounded_String; + From : in Positive; + Going : in Direction := Forward) + return Natural; + function Index_Non_Blank (Source : in Bounded_String; + Going : in Direction := Forward) + return Natural; + +A.4.4 Bounded-Length String Handling + +13 December 2012 386 + + Ada Reference Manual — 2012 Edition + + function Count (Source : in Bounded_String; + Pattern : in String; + Mapping : in Maps.Character_Mapping + := Maps.Identity) + return Natural; + function Count (Source : in Bounded_String; + Pattern : in String; + Mapping : in Maps.Character_Mapping_Function) + return Natural; + function Count (Source : in Bounded_String; + Set : in Maps.Character_Set) + return Natural; + procedure Find_Token (Source : in Bounded_String; + Set : in Maps.Character_Set; + From : in Positive; + Test : in Membership; + First : out Positive; + Last : out Natural); + procedure Find_Token (Source : in Bounded_String; + Set : in Maps.Character_Set; + Test : in Membership; + First : out Positive; + Last : out Natural); + -- String translation subprograms + function Translate (Source : in Bounded_String; + Mapping : in Maps.Character_Mapping) + return Bounded_String; + procedure Translate (Source : in out Bounded_String; + Mapping : in Maps.Character_Mapping); + function Translate (Source : in Bounded_String; + Mapping : in Maps.Character_Mapping_Function) + return Bounded_String; + procedure Translate (Source : in out Bounded_String; + Mapping : in Maps.Character_Mapping_Function); + -- String transformation subprograms + function Replace_Slice (Source : in Bounded_String; + Low : in Positive; + High : in Natural; + By : in String; + Drop : in Truncation := Error) + return Bounded_String; + procedure Replace_Slice (Source : in out Bounded_String; + Low : in Positive; + High : in Natural; + By : in String; + Drop : in Truncation := Error); + function Insert (Source : in Bounded_String; + Before : in Positive; + New_Item : in String; + Drop : in Truncation := Error) + return Bounded_String; + procedure Insert (Source : in out Bounded_String; + Before : in Positive; + New_Item : in String; + Drop : in Truncation := Error); + function Overwrite (Source : in Bounded_String; + Position : in Positive; + New_Item : in String; + Drop : in Truncation := Error) + return Bounded_String; + +48 + +49 + +50 + +50.1/3 + +51 + +52 + +53 + +54 + +55 + +56 + +57 + +58 + +59 + +60 + +61 + +62 + +387 13 December 2012 + +Bounded-Length String Handling A.4.4 + + Ada Reference Manual — 2012 Edition + +63 + +64 + +65 + +66 + +67 + +68 + +69 + +70 + +71 + +72 + +73 + +74 + +75 + +76 + +77 + +78 + + procedure Overwrite (Source : in out Bounded_String; + Position : in Positive; + New_Item : in String; + Drop : in Truncation := Error); + function Delete (Source : in Bounded_String; + From : in Positive; + Through : in Natural) + return Bounded_String; + procedure Delete (Source : in out Bounded_String; + From : in Positive; + Through : in Natural); + --String selector subprograms + function Trim (Source : in Bounded_String; + Side : in Trim_End) + return Bounded_String; + procedure Trim (Source : in out Bounded_String; + Side : in Trim_End); + function Trim (Source : in Bounded_String; + Left : in Maps.Character_Set; + Right : in Maps.Character_Set) + return Bounded_String; + procedure Trim (Source : in out Bounded_String; + Left : in Maps.Character_Set; + Right : in Maps.Character_Set); + function Head (Source : in Bounded_String; + Count : in Natural; + Pad : in Character := Space; + Drop : in Truncation := Error) + return Bounded_String; + procedure Head (Source : in out Bounded_String; + Count : in Natural; + Pad : in Character := Space; + Drop : in Truncation := Error); + function Tail (Source : in Bounded_String; + Count : in Natural; + Pad : in Character := Space; + Drop : in Truncation := Error) + return Bounded_String; + procedure Tail (Source : in out Bounded_String; + Count : in Natural; + Pad : in Character := Space; + Drop : in Truncation := Error); + --String constructor subprograms + function "*" (Left : in Natural; + Right : in Character) + return Bounded_String; + function "*" (Left : in Natural; + Right : in String) + return Bounded_String; + function "*" (Left : in Natural; + Right : in Bounded_String) + return Bounded_String; + function Replicate (Count : in Natural; + Item : in Character; + Drop : in Truncation := Error) + return Bounded_String; + +A.4.4 Bounded-Length String Handling + +13 December 2012 388 + + Ada Reference Manual — 2012 Edition + + function Replicate (Count : in Natural; + Item : in String; + Drop : in Truncation := Error) + return Bounded_String; + function Replicate (Count : in Natural; + Item : in Bounded_String; + Drop : in Truncation := Error) + return Bounded_String; + private + ... -- not specified by the language + end Generic_Bounded_Length; +end Ada.Strings.Bounded; + +Null_Bounded_String represents the null string. If an object of type Bounded_String is not otherwise +initialized, it will be initialized to the same value as Null_Bounded_String. + +function Length (Source : in Bounded_String) return Length_Range; + +The Length function returns the length of the string represented by Source. + +function To_Bounded_String (Source : in String; + Drop : in Truncation := Error) + return Bounded_String; + +79 + +80 + +81 + +82 + +83 + +84 + +85 + +86 + +If Source'Length <= Max_Length, then this function returns a Bounded_String that represents +Source. Otherwise, the effect depends on the value of Drop: + +87/3 + +• If Drop=Left, then the result is a Bounded_String that represents the string comprising + +the rightmost Max_Length characters of Source. + +• If Drop=Right, then the result is a Bounded_String that represents the string + +comprising the leftmost Max_Length characters of Source. + +• If Drop=Error, then Strings.Length_Error is propagated. + +function To_String (Source : in Bounded_String) return String; + +To_String returns the String value with lower bound 1 represented by Source. If B is a +Bounded_String, then B = To_Bounded_String(To_String(B)). + +procedure Set_Bounded_String + (Target : out Bounded_String; + Source : in String; + Drop : in Truncation := Error); + +Equivalent to Target := To_Bounded_String (Source, Drop); + +Each of the Append functions returns a Bounded_String obtained by concatenating the string or character +given or represented by one of the parameters, with the string or character given or represented by the +other parameter, and applying To_Bounded_String to the concatenation result string, with Drop as +provided to the Append function. + +Each of the procedures Append(Source, New_Item, Drop) has the same effect as the corresponding +assignment Source := Append(Source, New_Item, Drop). + +Each of the "&" functions has the same effect as the corresponding Append function, with Error as the +Drop parameter. + +88 + +89 + +90 + +91 + +92 + +92.1/2 + +92.2/2 + +93 + +94 + +95 + +389 13 December 2012 + +Bounded-Length String Handling A.4.4 + + 96 + +97 + +98 + +99 + +100 + +101/1 + +101.1/2 + +101.2/2 + +101.3/2 + +Ada Reference Manual — 2012 Edition + +function Element (Source : in Bounded_String; + Index : in Positive) + return Character; + +Returns the character at position Index in the string represented by Source; propagates +Index_Error if Index > Length(Source). + +procedure Replace_Element (Source : in out Bounded_String; + Index : in Positive; + By : in Character); + +Updates Source such that the character at position Index in the string represented by Source is +By; propagates Index_Error if Index > Length(Source). + +function Slice (Source : in Bounded_String; + Low : in Positive; + High : in Natural) + return String; + +Returns the slice at positions Low through High in the string represented by Source; propagates +Index_Error if Low > Length(Source)+1 or High > Length(Source). The bounds of the returned +string are Low and High.. + +function Bounded_Slice + (Source : in Bounded_String; + Low : in Positive; + High : in Natural) + return Bounded_String; + +Returns the slice at positions Low through High in the string represented by Source as a bounded +string; propagates Index_Error if Low > Length(Source)+1 or High > Length(Source). + +procedure Bounded_Slice + (Source : in Bounded_String; + Target : out Bounded_String; + Low : in Positive; + High : in Natural); + +101.4/2 + +Equivalent to Target := Bounded_Slice (Source, Low, High); + +102 + +103 + +104 + +105/1 + +Each of the functions "=", "<", ">", "<=", and ">=" returns the same result as the corresponding String +operation applied to the String values given or represented by the two parameters. + +Each of the search subprograms (Index, Index_Non_Blank, Count, Find_Token) has the same effect as the +corresponding subprogram in Strings.Fixed applied to the string represented by the Bounded_String +parameter. + +Each of the Translate subprograms, when applied to a Bounded_String, has an analogous effect to the +corresponding subprogram in Strings.Fixed. For the Translate function, the translation is applied to the +string represented by the Bounded_String parameter, and the result is converted (via To_Bounded_String) +to a Bounded_String. For the Translate procedure, the string represented by the Bounded_String parameter +after the translation is given by the Translate function for fixed-length strings applied to the string +represented by the original value of the parameter. + +Each of the transformation subprograms (Replace_Slice, Insert, Overwrite, Delete), selector subprograms +(Trim, Head, Tail), and constructor functions ("*") has an effect based on its corresponding subprogram in +Strings.Fixed, and Replicate is based on Fixed."*". In the case of a function, the corresponding fixed- +length string subprogram is applied to the string represented by the Bounded_String parameter. +To_Bounded_String +the case of +Generic_Bounded_Length."*") determining the effect when the string length exceeds Max_Length. In the + +string, with Drop + +is applied + +(or Error + +result + +the + +in + +A.4.4 Bounded-Length String Handling + +13 December 2012 390 + + Ada Reference Manual — 2012 Edition + +case of a procedure, the corresponding function in Strings.Bounded.Generic_Bounded_Length is applied, +with the result assigned into the Source parameter. + +Bounded string objects should not be implemented by implicit pointers and dynamic allocation. + +106 + +Implementation Advice + +A.4.5 Unbounded-Length String Handling + +The language-defined package Strings.Unbounded provides a private type Unbounded_String and a set of +operations. An object of type Unbounded_String represents a String whose low bound is 1 and whose +length can vary conceptually between 0 and Natural'Last. The subprograms for fixed-length string +handling are either overloaded directly for Unbounded_String, or are modified as needed to reflect the +flexibility in length. Since the Unbounded_String type is private, relevant constructor and selector +operations are provided. + +The library package Strings.Unbounded has the following declaration: + +Static Semantics + +with Ada.Strings.Maps; +package Ada.Strings.Unbounded is + pragma Preelaborate(Unbounded); + type Unbounded_String is private; + pragma Preelaborable_Initialization(Unbounded_String); + Null_Unbounded_String : constant Unbounded_String; + function Length (Source : in Unbounded_String) return Natural; + type String_Access is access all String; + procedure Free (X : in out String_Access); +-- Conversion, Concatenation, and Selection functions + function To_Unbounded_String (Source : in String) + return Unbounded_String; + function To_Unbounded_String (Length : in Natural) + return Unbounded_String; + function To_String (Source : in Unbounded_String) return String; + procedure Set_Unbounded_String + (Target : out Unbounded_String; + Source : in String); + procedure Append (Source : in out Unbounded_String; + New_Item : in Unbounded_String); + procedure Append (Source : in out Unbounded_String; + New_Item : in String); + procedure Append (Source : in out Unbounded_String; + New_Item : in Character); + function "&" (Left, Right : in Unbounded_String) + return Unbounded_String; + function "&" (Left : in Unbounded_String; Right : in String) + return Unbounded_String; + function "&" (Left : in String; Right : in Unbounded_String) + return Unbounded_String; + function "&" (Left : in Unbounded_String; Right : in Character) + return Unbounded_String; + function "&" (Left : in Character; Right : in Unbounded_String) + return Unbounded_String; + +1 + +2 + +3 + +4/2 + +5 + +6 + +7 + +8 + +9 + +10 + +11 + +11.1/2 + +12 + +13 + +14 + +15 + +16 + +17 + +18 + +19 + +391 13 December 2012 + +Bounded-Length String Handling A.4.4 + + Ada Reference Manual — 2012 Edition + +20 + +21 + +22 + +22.1/2 + +22.2/2 + +23 + +24 + +25 + +26 + +27 + +28 + +29 + +30 + +31 + +32 + +33 + +34 + +35 + +36 + +37 + +38 + +38.1/2 + + function Element (Source : in Unbounded_String; + Index : in Positive) + return Character; + procedure Replace_Element (Source : in out Unbounded_String; + Index : in Positive; + By : in Character); + function Slice (Source : in Unbounded_String; + Low : in Positive; + High : in Natural) + return String; + function Unbounded_Slice + (Source : in Unbounded_String; + Low : in Positive; + High : in Natural) + return Unbounded_String; + procedure Unbounded_Slice + (Source : in Unbounded_String; + Target : out Unbounded_String; + Low : in Positive; + High : in Natural); + function "=" (Left, Right : in Unbounded_String) return Boolean; + function "=" (Left : in Unbounded_String; Right : in String) + return Boolean; + function "=" (Left : in String; Right : in Unbounded_String) + return Boolean; + function "<" (Left, Right : in Unbounded_String) return Boolean; + function "<" (Left : in Unbounded_String; Right : in String) + return Boolean; + function "<" (Left : in String; Right : in Unbounded_String) + return Boolean; + function "<=" (Left, Right : in Unbounded_String) return Boolean; + function "<=" (Left : in Unbounded_String; Right : in String) + return Boolean; + function "<=" (Left : in String; Right : in Unbounded_String) + return Boolean; + function ">" (Left, Right : in Unbounded_String) return Boolean; + function ">" (Left : in Unbounded_String; Right : in String) + return Boolean; + function ">" (Left : in String; Right : in Unbounded_String) + return Boolean; + function ">=" (Left, Right : in Unbounded_String) return Boolean; + function ">=" (Left : in Unbounded_String; Right : in String) + return Boolean; + function ">=" (Left : in String; Right : in Unbounded_String) + return Boolean; +-- Search subprograms + function Index (Source : in Unbounded_String; + Pattern : in String; + From : in Positive; + Going : in Direction := Forward; + Mapping : in Maps.Character_Mapping := Maps.Identity) + return Natural; + +A.4.5 Unbounded-Length String Handling + +13 December 2012 392 + + Ada Reference Manual — 2012 Edition + + function Index (Source : in Unbounded_String; + Pattern : in String; + From : in Positive; + Going : in Direction := Forward; + Mapping : in Maps.Character_Mapping_Function) + return Natural; + function Index (Source : in Unbounded_String; + Pattern : in String; + Going : in Direction := Forward; + Mapping : in Maps.Character_Mapping + := Maps.Identity) + return Natural; + function Index (Source : in Unbounded_String; + Pattern : in String; + Going : in Direction := Forward; + Mapping : in Maps.Character_Mapping_Function) + return Natural; + function Index (Source : in Unbounded_String; + Set : in Maps.Character_Set; + From : in Positive; + Test : in Membership := Inside; + Going : in Direction := Forward) + return Natural; + function Index (Source : in Unbounded_String; + Set : in Maps.Character_Set; + Test : in Membership := Inside; + Going : in Direction := Forward) return Natural; + function Index_Non_Blank (Source : in Unbounded_String; + From : in Positive; + Going : in Direction := Forward) + return Natural; + function Index_Non_Blank (Source : in Unbounded_String; + Going : in Direction := Forward) + return Natural; + function Count (Source : in Unbounded_String; + Pattern : in String; + Mapping : in Maps.Character_Mapping + := Maps.Identity) + return Natural; + function Count (Source : in Unbounded_String; + Pattern : in String; + Mapping : in Maps.Character_Mapping_Function) + return Natural; + function Count (Source : in Unbounded_String; + Set : in Maps.Character_Set) + return Natural; + procedure Find_Token (Source : in Unbounded_String; + Set : in Maps.Character_Set; + From : in Positive; + Test : in Membership; + First : out Positive; + Last : out Natural); + procedure Find_Token (Source : in Unbounded_String; + Set : in Maps.Character_Set; + Test : in Membership; + First : out Positive; + Last : out Natural); +-- String translation subprograms + function Translate (Source : in Unbounded_String; + Mapping : in Maps.Character_Mapping) + return Unbounded_String; + +38.2/2 + +39 + +40 + +40.1/2 + +41 + +41.1/2 + +42 + +43 + +44 + +45 + +45.1/3 + +46 + +47 + +48 + +393 13 December 2012 + +Unbounded-Length String Handling A.4.5 + + Ada Reference Manual — 2012 Edition + +49 + +50 + +51 + +52 + +53 + +54 + +55 + +56 + +57 + +58 + +59 + +60 + +61 + +62 + +63 + +64 + +65 + +66 + + procedure Translate (Source : in out Unbounded_String; + Mapping : in Maps.Character_Mapping); + function Translate (Source : in Unbounded_String; + Mapping : in Maps.Character_Mapping_Function) + return Unbounded_String; + procedure Translate (Source : in out Unbounded_String; + Mapping : in Maps.Character_Mapping_Function); +-- String transformation subprograms + function Replace_Slice (Source : in Unbounded_String; + Low : in Positive; + High : in Natural; + By : in String) + return Unbounded_String; + procedure Replace_Slice (Source : in out Unbounded_String; + Low : in Positive; + High : in Natural; + By : in String); + function Insert (Source : in Unbounded_String; + Before : in Positive; + New_Item : in String) + return Unbounded_String; + procedure Insert (Source : in out Unbounded_String; + Before : in Positive; + New_Item : in String); + function Overwrite (Source : in Unbounded_String; + Position : in Positive; + New_Item : in String) + return Unbounded_String; + procedure Overwrite (Source : in out Unbounded_String; + Position : in Positive; + New_Item : in String); + function Delete (Source : in Unbounded_String; + From : in Positive; + Through : in Natural) + return Unbounded_String; + procedure Delete (Source : in out Unbounded_String; + From : in Positive; + Through : in Natural); + function Trim (Source : in Unbounded_String; + Side : in Trim_End) + return Unbounded_String; + procedure Trim (Source : in out Unbounded_String; + Side : in Trim_End); + function Trim (Source : in Unbounded_String; + Left : in Maps.Character_Set; + Right : in Maps.Character_Set) + return Unbounded_String; + procedure Trim (Source : in out Unbounded_String; + Left : in Maps.Character_Set; + Right : in Maps.Character_Set); + function Head (Source : in Unbounded_String; + Count : in Natural; + Pad : in Character := Space) + return Unbounded_String; + procedure Head (Source : in out Unbounded_String; + Count : in Natural; + Pad : in Character := Space); + +A.4.5 Unbounded-Length String Handling + +13 December 2012 394 + + Ada Reference Manual — 2012 Edition + + function Tail (Source : in Unbounded_String; + Count : in Natural; + Pad : in Character := Space) + return Unbounded_String; + procedure Tail (Source : in out Unbounded_String; + Count : in Natural; + Pad : in Character := Space); + function "*" (Left : in Natural; + Right : in Character) + return Unbounded_String; + function "*" (Left : in Natural; + Right : in String) + return Unbounded_String; + function "*" (Left : in Natural; + Right : in Unbounded_String) + return Unbounded_String; +private + ... -- not specified by the language +end Ada.Strings.Unbounded; + +67 + +68 + +69 + +70 + +71 + +72 + +The type Unbounded_String needs finalization (see 7.6). + +72.1/2 + +Null_Unbounded_String represents the null String. If an object of type Unbounded_String is not otherwise +initialized, it will be initialized to the same value as Null_Unbounded_String. + +The function Length returns the length of the String represented by Source. + +The type String_Access provides a (nonprivate) access type for explicit processing of unbounded-length +strings. The procedure Free performs an unchecked deallocation of an object of type String_Access. + +The function To_Unbounded_String(Source : in String) returns an Unbounded_String that represents +Source. The function To_Unbounded_String(Length : in Natural) returns an Unbounded_String that +represents an uninitialized String whose length is Length. + +The function To_String returns the String with lower bound 1 represented by Source. To_String and +To_Unbounded_String are related as follows: + +• If S is a String, then To_String(To_Unbounded_String(S)) = S. +• If U is an Unbounded_String, then To_Unbounded_String(To_String(U)) = U. + +73 + +74 + +75 + +76 + +77 + +78 + +79 + +The procedure Set_Unbounded_String sets Target to an Unbounded_String that represents Source. + +79.1/2 + +For each of the Append procedures, the resulting string represented by the Source parameter is given by +the concatenation of the original value of Source and the value of New_Item. + +Each of the "&" functions returns an Unbounded_String obtained by concatenating the string or character +given or represented by one of the parameters, with the string or character given or represented by the +other parameter, and applying To_Unbounded_String to the concatenation result string. + +The Element, Replace_Element, and Slice subprograms have the same effect as the corresponding +bounded-length string subprograms. + +80 + +81 + +82 + +The function Unbounded_Slice returns the slice at positions Low through High in the string represented by +Source as an Unbounded_String. The procedure Unbounded_Slice sets Target to the Unbounded_String +representing the slice at positions Low through High in the string represented by Source. Both +subprograms propagate Index_Error if Low > Length(Source)+1 or High > Length(Source). + +82.1/3 + +395 13 December 2012 + +Unbounded-Length String Handling A.4.5 + + Ada Reference Manual — 2012 Edition + +83 + +84 + +85 + +86 + +87 + +Each of the functions "=", "<", ">", "<=", and ">=" returns the same result as the corresponding String +operation applied to the String values given or represented by Left and Right. + +Each of the search subprograms (Index, Index_Non_Blank, Count, Find_Token) has the same effect as the +corresponding subprogram in Strings.Fixed applied to the string represented by the Unbounded_String +parameter. + +The Translate function has an analogous effect to the corresponding subprogram in Strings.Fixed. The +translation is applied to the string represented by the Unbounded_String parameter, and the result is +converted (via To_Unbounded_String) to an Unbounded_String. + +Each of the transformation functions (Replace_Slice, Insert, Overwrite, Delete), selector functions (Trim, +Head, Tail), and constructor functions ("*") is likewise analogous to its corresponding subprogram in +Strings.Fixed. For each of the subprograms, the corresponding fixed-length string subprogram is applied to +the string represented by the Unbounded_String parameter, and To_Unbounded_String is applied the +result string. + +For each of the procedures Translate, Replace_Slice, Insert, Overwrite, Delete, Trim, Head, and Tail, the +resulting string represented by the Source parameter is given by the corresponding function for fixed- +length strings applied to the string represented by Source's original value. + +88 + +No storage associated with an Unbounded_String object shall be lost upon assignment or scope exit. + +Implementation Requirements + +A.4.6 String-Handling Sets and Mappings + +1 + +The language-defined package Strings.Maps.Constants declares Character_Set and Character_Mapping +constants corresponding to classification and conversion functions in package Characters.Handling. + +2 + +3/2 + +4 + +5 + +6 + +The library package Strings.Maps.Constants has the following declaration: + +Static Semantics + +package Ada.Strings.Maps.Constants is + pragma Pure(Constants); + Control_Set : constant Character_Set; + Graphic_Set : constant Character_Set; + Letter_Set : constant Character_Set; + Lower_Set : constant Character_Set; + Upper_Set : constant Character_Set; + Basic_Set : constant Character_Set; + Decimal_Digit_Set : constant Character_Set; + Hexadecimal_Digit_Set : constant Character_Set; + Alphanumeric_Set : constant Character_Set; + Special_Set : constant Character_Set; + ISO_646_Set : constant Character_Set; + Lower_Case_Map : constant Character_Mapping; + --Maps to lower case for letters, else identity + Upper_Case_Map : constant Character_Mapping; + --Maps to upper case for letters, else identity + Basic_Map : constant Character_Mapping; + --Maps to basic letter for letters, else identity +private + ... -- not specified by the language +end Ada.Strings.Maps.Constants; + +A.4.5 Unbounded-Length String Handling + +13 December 2012 396 + + Ada Reference Manual — 2012 Edition + +Each of these constants represents a correspondingly named set of characters or character mapping in +Characters.Handling (see A.3.2). + +NOTES +15 There are certain characters which are defined to be lower case letters by ISO 10646 and are therefore allowed in +identifiers, but are not considered lower case letters by Ada.Strings.Maps.Constants. + +A.4.7 Wide_String Handling + +Facilities for handling strings of Wide_Character elements are found in the packages Strings.Wide_Maps, +Strings.Wide_Fixed, Strings.Wide_Bounded, Strings.Wide_Unbounded, and Strings.Wide_Maps.Wide_- +Constants, and in the library functions Strings.Wide_Hash, Strings.Wide_Fixed.Wide_Hash, Strings.- +Wide_Bounded.Wide_Hash, +Strings.Wide_Hash_Case_- +Strings.Wide_Unbounded.Wide_Hash, +Insensitive, Strings.Wide_Fixed.Wide_Hash_Case_Insensitive, Strings.Wide_Bounded.Wide_Hash_- +Case_Insensitive, Strings.Wide_Unbounded.Wide_Hash_Case_Insensitive, Strings.Wide_Equal_Case_- +Insensitive, Strings.Wide_Fixed.Wide_Equal_Case_Insensitive, Strings.Wide_Bounded.Wide_Equal_- +Case_Insensitive, and Strings.Wide_Unbounded.Wide_Equal_Case_Insensitive. They provide the same +string-handling operations as the corresponding packages and functions for strings of Character elements. + +The package Strings.Wide_Maps has the following declaration. + +Static Semantics + +package Ada.Strings.Wide_Maps is + pragma Preelaborate(Wide_Maps); + -- Representation for a set of Wide_Character values: + type Wide_Character_Set is private; + pragma Preelaborable_Initialization(Wide_Character_Set); + Null_Set : constant Wide_Character_Set; + type Wide_Character_Range is + record + Low : Wide_Character; + High : Wide_Character; + end record; + -- Represents Wide_Character range Low..High + type Wide_Character_Ranges is array (Positive range <>) + of Wide_Character_Range; + function To_Set (Ranges : in Wide_Character_Ranges) + return Wide_Character_Set; + function To_Set (Span : in Wide_Character_Range) + return Wide_Character_Set; + function To_Ranges (Set : in Wide_Character_Set) + return Wide_Character_Ranges; + function "=" (Left, Right : in Wide_Character_Set) return Boolean; + function "not" (Right : in Wide_Character_Set) + return Wide_Character_Set; + function "and" (Left, Right : in Wide_Character_Set) + return Wide_Character_Set; + function "or" (Left, Right : in Wide_Character_Set) + return Wide_Character_Set; + function "xor" (Left, Right : in Wide_Character_Set) + return Wide_Character_Set; + function "-" (Left, Right : in Wide_Character_Set) + return Wide_Character_Set; + function Is_In (Element : in Wide_Character; + Set : in Wide_Character_Set) + return Boolean; + +7 + +8/3 + +1/3 + +2 + +3 + +4/2 + +5 + +6 + +7 + +8 + +9 + +10 + +11 + +12 + +13 + +397 13 December 2012 + +String-Handling Sets and Mappings A.4.6 + + Ada Reference Manual — 2012 Edition + + function Is_Subset (Elements : in Wide_Character_Set; + Set : in Wide_Character_Set) + return Boolean; + function "<=" (Left : in Wide_Character_Set; + Right : in Wide_Character_Set) + return Boolean renames Is_Subset; + -- Alternative representation for a set of Wide_Character values: + subtype Wide_Character_Sequence is Wide_String; + function To_Set (Sequence : in Wide_Character_Sequence) + return Wide_Character_Set; + function To_Set (Singleton : in Wide_Character) + return Wide_Character_Set; + function To_Sequence (Set : in Wide_Character_Set) + return Wide_Character_Sequence; + -- Representation for a Wide_Character to Wide_Character mapping: + type Wide_Character_Mapping is private; + pragma Preelaborable_Initialization(Wide_Character_Mapping); + function Value (Map : in Wide_Character_Mapping; + Element : in Wide_Character) + return Wide_Character; + Identity : constant Wide_Character_Mapping; + function To_Mapping (From, To : in Wide_Character_Sequence) + return Wide_Character_Mapping; + function To_Domain (Map : in Wide_Character_Mapping) + return Wide_Character_Sequence; + function To_Range (Map : in Wide_Character_Mapping) + return Wide_Character_Sequence; + type Wide_Character_Mapping_Function is + access function (From : in Wide_Character) return Wide_Character; +private + ... -- not specified by the language +end Ada.Strings.Wide_Maps; + +The context clause for each of the packages Strings.Wide_Fixed, Strings.Wide_Bounded, and +Strings.Wide_Unbounded identifies Strings.Wide_Maps instead of Strings.Maps. + +14 + +15 + +16 + +17 + +18 + +19 + +20/2 + +21 + +22 + +23 + +24 + +25 + +26 + +27 + +28 + +28.1/3 + +Types Wide_Character_Set and Wide_Character_Mapping need finalization. + +29/3 + +30 + +31 + +32 + +33 + +34 + +35 + +36 + +of + +each + +packages +and + +Strings.Fixed, +library + +and +For +the +Strings.Maps.Constants, +Strings.Fixed.Hash, +Strings.Bounded.Hash, Strings.Unbounded.Hash, Strings.Hash_Case_Insensitive, Strings.Fixed.Hash_- +Case_Insensitive, Strings.Bounded.Hash_Case_Insensitive, Strings.Unbounded.Hash_Case_Insensitive, +Strings.Equal_Case_Insensitive, Strings.Fixed.Equal_Case_Insensitive, Strings.Bounded.Equal_Case_- +Insensitive, and Strings.Unbounded.Equal_Case_Insensitive, the corresponding wide string package or +function has the same contents except that + +Strings.Unbounded, + +Strings.Bounded, + +Strings.Hash, + +functions + +for + +• Wide_Space replaces Space +• Wide_Character replaces Character +• Wide_String replaces String +• Wide_Character_Set replaces Character_Set +• Wide_Character_Mapping replaces Character_Mapping +• Wide_Character_Mapping_Function replaces Character_Mapping_Function +• Wide_Maps replaces Maps + +A.4.7 Wide_String Handling + +13 December 2012 398 + + Ada Reference Manual — 2012 Edition + +• Bounded_Wide_String replaces Bounded_String +• Null_Bounded_Wide_String replaces Null_Bounded_String +• To_Bounded_Wide_String replaces To_Bounded_String +• To_Wide_String replaces To_String +• Set_Bounded_Wide_String replaces Set_Bounded_String +• Unbounded_Wide_String replaces Unbounded_String +• Null_Unbounded_Wide_String replaces Null_Unbounded_String +• Wide_String_Access replaces String_Access +• To_Unbounded_Wide_String replaces To_Unbounded_String +• Set_Unbounded_Wide_String replaces Set_Unbounded_String + +The following additional declaration is present in Strings.Wide_Maps.Wide_Constants: + +Character_Set : constant Wide_Maps.Wide_Character_Set; +--Contains each Wide_Character value WC such that +--Characters.Conversions.Is_Character(WC) is True + +Each Wide_Character_Set constant in the package Strings.Wide_Maps.Wide_Constants contains no +values outside the Character portion of Wide_Character. Similarly, each Wide_Character_Mapping +constant in this package is the identity mapping when applied to any element outside the Character portion +of Wide_Character. + +Pragma Pure is replaced by pragma Preelaborate in Strings.Wide_Maps.Wide_Constants. + +NOTES +16 If a null Wide_Character_Mapping_Function is passed to any of the Wide_String handling subprograms, +Constraint_Error is propagated. + +A.4.8 Wide_Wide_String Handling + +Facilities for handling strings of Wide_Wide_Character elements are found in the packages Strings.- +Wide_Wide_Maps, Strings.Wide_Wide_Fixed, Strings.Wide_Wide_Bounded, Strings.Wide_Wide_- +Unbounded, and Strings.Wide_Wide_Maps.Wide_Wide_Constants, and in the library functions Strings.- +Wide_Wide_Hash, Strings.Wide_Wide_Fixed.Wide_Wide_Hash, Strings.Wide_Wide_Bounded.Wide_- +Strings.Wide_Wide_Hash_Case_- +Wide_Hash, +Strings.Wide_Wide_- +Insensitive, +Bounded.Wide_Wide_Hash_Case_Insensitive, +Strings.Wide_Wide_Unbounded.Wide_Wide_Hash_- +Case_Insensitive, Strings.Wide_Wide_Equal_Case_Insensitive, Strings.Wide_Wide_Fixed.Wide_Wide_- +Equal_Case_Insensitive, +and +Strings.Wide_Wide_Unbounded.Wide_Wide_Equal_Case_Insensitive. They provide the same string- +handling operations as the corresponding packages and functions for strings of Character elements. + +Strings.Wide_Wide_Unbounded.Wide_Wide_Hash, +Strings.Wide_Wide_Fixed.Wide_Wide_Hash_Case_Insensitive, + +Strings.Wide_Wide_Bounded.Wide_Wide_Equal_Case_Insensitive, + +Static Semantics + +The library package Strings.Wide_Wide_Maps has the following declaration. + +package Ada.Strings.Wide_Wide_Maps is + pragma Preelaborate(Wide_Wide_Maps); + -- Representation for a set of Wide_Wide_Character values: + type Wide_Wide_Character_Set is private; + pragma Preelaborable_Initialization(Wide_Wide_Character_Set); + Null_Set : constant Wide_Wide_Character_Set; + +399 13 December 2012 + +Wide_String Handling A.4.7 + +37 + +38 + +39 + +40 + +40.1/2 + +41 + +42 + +43 + +44 + +44.1/2 + +45 + +46/2 + +46.1/2 + +46.2/2 + +47 + +1/3 + +2/2 + +3/2 + +4/2 + +5/2 + + Ada Reference Manual — 2012 Edition + +6/2 + +7/2 + +8/2 + +9/2 + +10/2 + +11/2 + +12/2 + +13/2 + +14/2 + +15/2 + +16/2 + +17/2 + +18/2 + +19/2 + +20/2 + +21/2 + +22/2 + +23/2 + +24/2 + +25/2 + + type Wide_Wide_Character_Range is + record + Low : Wide_Wide_Character; + High : Wide_Wide_Character; + end record; + -- Represents Wide_Wide_Character range Low..High + type Wide_Wide_Character_Ranges is array (Positive range <>) + of Wide_Wide_Character_Range; + function To_Set (Ranges : in Wide_Wide_Character_Ranges) + return Wide_Wide_Character_Set; + function To_Set (Span : in Wide_Wide_Character_Range) + return Wide_Wide_Character_Set; + function To_Ranges (Set : in Wide_Wide_Character_Set) + return Wide_Wide_Character_Ranges; + function "=" (Left, Right : in Wide_Wide_Character_Set) return Boolean; + function "not" (Right : in Wide_Wide_Character_Set) + return Wide_Wide_Character_Set; + function "and" (Left, Right : in Wide_Wide_Character_Set) + return Wide_Wide_Character_Set; + function "or" (Left, Right : in Wide_Wide_Character_Set) + return Wide_Wide_Character_Set; + function "xor" (Left, Right : in Wide_Wide_Character_Set) + return Wide_Wide_Character_Set; + function "-" (Left, Right : in Wide_Wide_Character_Set) + return Wide_Wide_Character_Set; + function Is_In (Element : in Wide_Wide_Character; + Set : in Wide_Wide_Character_Set) + return Boolean; + function Is_Subset (Elements : in Wide_Wide_Character_Set; + Set : in Wide_Wide_Character_Set) + return Boolean; + function "<=" (Left : in Wide_Wide_Character_Set; + Right : in Wide_Wide_Character_Set) + return Boolean renames Is_Subset; + -- Alternative representation for a set of Wide_Wide_Character values: + subtype Wide_Wide_Character_Sequence is Wide_Wide_String; + function To_Set (Sequence : in Wide_Wide_Character_Sequence) + return Wide_Wide_Character_Set; + function To_Set (Singleton : in Wide_Wide_Character) + return Wide_Wide_Character_Set; + function To_Sequence (Set : in Wide_Wide_Character_Set) + return Wide_Wide_Character_Sequence; + -- Representation for a Wide_Wide_Character to Wide_Wide_Character + -- mapping: + type Wide_Wide_Character_Mapping is private; + pragma Preelaborable_Initialization(Wide_Wide_Character_Mapping); + function Value (Map : in Wide_Wide_Character_Mapping; + Element : in Wide_Wide_Character) + return Wide_Wide_Character; + Identity : constant Wide_Wide_Character_Mapping; + function To_Mapping (From, To : in Wide_Wide_Character_Sequence) + return Wide_Wide_Character_Mapping; + function To_Domain (Map : in Wide_Wide_Character_Mapping) + return Wide_Wide_Character_Sequence; + function To_Range (Map : in Wide_Wide_Character_Mapping) + return Wide_Wide_Character_Sequence; + +A.4.8 Wide_Wide_String Handling + +13 December 2012 400 + + Ada Reference Manual — 2012 Edition + + type Wide_Wide_Character_Mapping_Function is + access function (From : in Wide_Wide_Character) + return Wide_Wide_Character; +private + ... -- not specified by the language +end Ada.Strings.Wide_Wide_Maps; + +The context clause for each of the packages Strings.Wide_Wide_Fixed, Strings.Wide_Wide_Bounded, and +Strings.Wide_Wide_Unbounded identifies Strings.Wide_Wide_Maps instead of Strings.Maps. + +Types Wide_Wide_Character_Set and Wide_Wide_Character_Mapping need finalization. + +For each of +the packages Strings.Fixed, Strings.Bounded, Strings.Unbounded, and Strings.- +Maps.Constants, and for library functions Strings.Hash, Strings.Fixed.Hash, Strings.Bounded.Hash, +Strings.Unbounded.Hash, Strings.Hash_Case_Insensitive, Strings.Fixed.Hash_Case_Insensitive, Strings.- +Bounded.Hash_Case_Insensitive, +Strings.Equal_Case_- +Insensitive, Strings.Fixed.Equal_Case_Insensitive, Strings.Bounded.Equal_Case_Insensitive, and Strings.- +Unbounded.Equal_Case_Insensitive, the corresponding wide wide string package or function has the same +contents except that + +Strings.Unbounded.Hash_Case_Insensitive, + +• Wide_Wide_Space replaces Space +• Wide_Wide_Character replaces Character +• Wide_Wide_String replaces String +• Wide_Wide_Character_Set replaces Character_Set +• Wide_Wide_Character_Mapping replaces Character_Mapping +• Wide_Wide_Character_Mapping_Function replaces Character_Mapping_Function +• Wide_Wide_Maps replaces Maps +• Bounded_Wide_Wide_String replaces Bounded_String +• Null_Bounded_Wide_Wide_String replaces Null_Bounded_String +• To_Bounded_Wide_Wide_String replaces To_Bounded_String +• To_Wide_Wide_String replaces To_String +• Set_Bounded_Wide_Wide_String replaces Set_Bounded_String +• Unbounded_Wide_Wide_String replaces Unbounded_String +• Null_Unbounded_Wide_Wide_String replaces Null_Unbounded_String +• Wide_Wide_String_Access replaces String_Access +• To_Unbounded_Wide_Wide_String replaces To_Unbounded_String +• Set_Unbounded_Wide_Wide_String replaces Set_Unbounded_String + +The following additional declarations are present in Strings.Wide_Wide_Maps.Wide_Wide_Constants: + +Character_Set : constant Wide_Wide_Maps.Wide_Wide_Character_Set; +-- Contains each Wide_Wide_Character value WWC such that +-- Characters.Conversions.Is_Character(WWC) is True +Wide_Character_Set : constant Wide_Wide_Maps.Wide_Wide_Character_Set; +-- Contains each Wide_Wide_Character value WWC such that +-- Characters.Conversions.Is_Wide_Character(WWC) is True + +26/2 + +27/2 + +28/2 + +28.1/3 + +29/3 + +30/2 + +31/2 + +32/2 + +33/2 + +34/2 + +35/2 + +36/2 + +37/2 + +38/2 + +39/2 + +40/2 + +41/2 + +42/2 + +43/2 + +44/2 + +45/2 + +46/2 + +47/2 + +48/2 + +Each Wide_Wide_Character_Set constant in the package Strings.Wide_Wide_Maps.Wide_Wide_- +Constants contains no values outside the Character portion of Wide_Wide_Character. Similarly, each + +49/2 + +401 13 December 2012 + +Wide_Wide_String Handling A.4.8 + + Ada Reference Manual — 2012 Edition + +Wide_Wide_Character_Mapping constant in this package is the identity mapping when applied to any +element outside the Character portion of Wide_Wide_Character. + +50/2 + +Pragma Pure is replaced by pragma Preelaborate in Strings.Wide_Wide_Maps.Wide_Wide_Constants. + +51/2 + +NOTES +17 If a null Wide_Wide_Character_Mapping_Function is passed to any of the Wide_Wide_String handling subprograms, +Constraint_Error is propagated. + +A.4.9 String Hashing + +The library function Strings.Hash has the following declaration: + +Static Semantics + +with Ada.Containers; +function Ada.Strings.Hash (Key : String) return Containers.Hash_Type; +pragma Pure(Ada.Strings.Hash); + +Returns an implementation-defined value which is a function of the value of Key. If A and B are +strings such that A equals B, Hash(A) equals Hash(B). + +The library function Strings.Fixed.Hash has the following declaration: + +with Ada.Containers, Ada.Strings.Hash; +function Ada.Strings.Fixed.Hash (Key : String) return Containers.Hash_Type + renames Ada.Strings.Hash; + +The generic library function Strings.Bounded.Hash has the following declaration: + +with Ada.Containers; +generic + with package Bounded is + new Ada.Strings.Bounded.Generic_Bounded_Length (<>); +function Ada.Strings.Bounded.Hash (Key : Bounded.Bounded_String) + return Containers.Hash_Type; +pragma Preelaborate(Ada.Strings.Bounded.Hash); + +Equivalent to Strings.Hash (Bounded.To_String (Key)); + +The library function Strings.Unbounded.Hash has the following declaration: + +with Ada.Containers; +function Ada.Strings.Unbounded.Hash (Key : Unbounded_String) + return Containers.Hash_Type; +pragma Preelaborate(Ada.Strings.Unbounded.Hash); + +Equivalent to Strings.Hash (To_String (Key)); + +1/2 + +2/3 + +3/2 + +4/2 + +5/3 + +6/2 + +7/3 + +8/3 + +9/2 + +10/3 + +11/3 + +11.1/3 + +The library function Strings.Hash_Case_Insensitive has the following declaration: + +11.2/3 + +11.3/3 + +with Ada.Containers; +function Ada.Strings.Hash_Case_Insensitive (Key : String) + return Containers.Hash_Type; +pragma Pure(Ada.Strings.Hash_Case_Insensitive); + +Returns an implementation-defined value which is a function of the value of Key, converted to +lower case. If A and B are strings such that Strings.Equal_Case_Insensitive (A, B) (see A.4.10) +is True, then Hash_Case_Insensitive(A) equals Hash_Case_Insensitive(B). + +11.4/3 + +The library function Strings.Fixed.Hash_Case_Insensitive has the following declaration: + +11.5/3 + +with Ada.Containers, Ada.Strings.Hash_Case_Insensitive; +function Ada.Strings.Fixed.Hash_Case_Insensitive (Key : String) + return Containers.Hash_Type renames Ada.Strings.Hash_Case_Insensitive; + +A.4.8 Wide_Wide_String Handling + +13 December 2012 402 + + Ada Reference Manual — 2012 Edition + +The generic library function Strings.Bounded.Hash_Case_Insensitive has the following declaration: + +with Ada.Containers; +generic + with package Bounded is + new Ada.Strings.Bounded.Generic_Bounded_Length (<>); +function Ada.Strings.Bounded.Hash_Case_Insensitive + (Key : Bounded.Bounded_String) return Containers.Hash_Type; +pragma Preelaborate(Ada.Strings.Bounded.Hash_Case_Insensitive); + +Equivalent to Strings.Hash_Case_Insensitive (Bounded.To_String (Key)); + +The library function Strings.Unbounded.Hash_Case_Insensitive has the following declaration: + +with Ada.Containers; +function Ada.Strings.Unbounded.Hash_Case_Insensitive + (Key : Unbounded_String) return Containers.Hash_Type; +pragma Preelaborate(Ada.Strings.Unbounded.Hash_Case_Insensitive); + +Equivalent to Strings.Hash_Case_Insensitive (To_String (Key)); + +11.6/3 + +11.7/3 + +11.8/3 + +11.9/3 + +11.10/3 + +11.11/3 + +The Hash functions should be good hash functions, returning a wide spread of values for different string +values. It should be unlikely for similar strings to return the same value. + +12/2 + +Implementation Advice + +A.4.10 String Comparison + +The library function Strings.Equal_Case_Insensitive has the following declaration: + +function Ada.Strings.Equal_Case_Insensitive (Left, Right : String) + return Boolean; +pragma Pure(Ada.Strings.Equal_Case_Insensitive); + +Static Semantics + +Returns True if the strings consist of the same sequence of characters after applying locale- +independent simple case folding, as defined by documents referenced in the note in Clause 1 of +ISO/IEC 10646:2011. Otherwise, returns False. This function uses the same method as is used to +determine whether two identifiers are the same. + +The library function Strings.Fixed.Equal_Case_Insensitive has the following declaration: + +with Ada.Strings.Equal_Case_Insensitive; +function Ada.Strings.Fixed.Equal_Case_Insensitive + (Left, Right : String) return Boolean + renames Ada.Strings.Equal_Case_Insensitive; + +The generic library function Strings.Bounded.Equal_Case_Insensitive has the following declaration: + +generic + with package Bounded is + new Ada.Strings.Bounded.Generic_Bounded_Length (<>); +function Ada.Strings.Bounded.Equal_Case_Insensitive + (Left, Right : Bounded.Bounded_String) return Boolean; +pragma Preelaborate(Ada.Strings.Bounded.Equal_Case_Insensitive); + +1/3 + +2/3 + +3/3 + +4/3 + +5/3 + +6/3 + +7/3 + +Equivalent to Strings.Equal_Case_Insensitive (Bounded.To_String (Left), Bounded.To_String +(Right)); + +8/3 + +The library function Strings.Unbounded.Equal_Case_Insensitive has the following declaration: + +function Ada.Strings.Unbounded.Equal_Case_Insensitive + (Left, Right : Unbounded_String) return Boolean; +pragma Preelaborate(Ada.Strings.Unbounded.Equal_Case_Insensitive); + +9/3 + +10/3 + +403 13 December 2012 + +String Hashing A.4.9 + + 11/3 + +12/3 + +13/3 + +14/3 + +15/3 + +16/3 + +17/3 + +18/3 + +19/3 + +20/3 + +21/3 + +22/3 + +1/3 + +2/3 + +3/3 + +4/3 + +5/3 + +6/3 + +7/3 + +8/3 + +9/3 + +Ada Reference Manual — 2012 Edition + +Equivalent to Strings.Equal_Case_Insensitive (To_String (Left), To_String (Right)); + +The library function Strings.Less_Case_Insensitive has the following declaration: + +function Ada.Strings.Less_Case_Insensitive (Left, Right : String) + return Boolean; +pragma Pure(Ada.Strings.Less_Case_Insensitive); + +Performs a lexicographic comparison of strings Left and Right, converted to lower case. + +The library function Strings.Fixed.Less_Case_Insensitive has the following declaration: + +with Ada.Strings.Less_Case_Insensitive; +function Ada.Strings.Fixed.Less_Case_Insensitive + (Left, Right : String) return Boolean + renames Ada.Strings.Less_Case_Insensitive; + +The generic library function Strings.Bounded.Less_Case_Insensitive has the following declaration: + +generic + with package Bounded is + new Ada.Strings.Bounded.Generic_Bounded_Length (<>); +function Ada.Strings.Bounded.Less_Case_Insensitive + (Left, Right : Bounded.Bounded_String) return Boolean; +pragma Preelaborate(Ada.Strings.Bounded.Less_Case_Insensitive); + +Equivalent to Strings.Less_Case_Insensitive (Bounded.To_String (Left), Bounded.To_String +(Right)); + +The library function Strings.Unbounded.Less_Case_Insensitive has the following declaration: + +function Ada.Strings.Unbounded.Less_Case_Insensitive + (Left, Right : Unbounded_String) return Boolean; +pragma Preelaborate(Ada.Strings.Unbounded.Less_Case_Insensitive); + +Equivalent to Strings.Less_Case_Insensitive (To_String (Left), To_String (Right)); + +A.4.11 String Encoding + +Facilities for encoding, decoding, and converting strings in various character encoding schemes are +provided +Strings.- +UTF_Encoding.Strings, +Strings.UTF_Encoding.- +Wide_Wide_Strings. + +Strings.UTF_Encoding.Wide_Strings, + +Strings.UTF_Encoding.Conversions, + +Strings.UTF_Encoding, + +packages + +and + +by + +The encoding library packages have the following declarations: + +Static Semantics + +package Ada.Strings.UTF_Encoding is + pragma Pure (UTF_Encoding); + -- Declarations common to the string encoding packages + type Encoding_Scheme is (UTF_8, UTF_16BE, UTF_16LE); + subtype UTF_String is String; + subtype UTF_8_String is String; + subtype UTF_16_Wide_String is Wide_String; + Encoding_Error : exception; + BOM_8 : constant UTF_8_String := + Character'Val(16#EF#) & + Character'Val(16#BB#) & + Character'Val(16#BF#); + +A.4.10 String Comparison + +13 December 2012 404 + + Ada Reference Manual — 2012 Edition + + BOM_16BE : constant UTF_String := + Character'Val(16#FE#) & + Character'Val(16#FF#); + BOM_16LE : constant UTF_String := + Character'Val(16#FF#) & + Character'Val(16#FE#); + BOM_16 : constant UTF_16_Wide_String := + (1 => Wide_Character'Val(16#FEFF#)); + function Encoding (Item : UTF_String; + Default : Encoding_Scheme := UTF_8) + return Encoding_Scheme; +end Ada.Strings.UTF_Encoding; +package Ada.Strings.UTF_Encoding.Conversions is + pragma Pure (Conversions); + -- Conversions between various encoding schemes + function Convert (Item : UTF_String; + Input_Scheme : Encoding_Scheme; + Output_Scheme : Encoding_Scheme; + Output_BOM : Boolean := False) return UTF_String; + function Convert (Item : UTF_String; + Input_Scheme : Encoding_Scheme; + Output_BOM : Boolean := False) + return UTF_16_Wide_String; + function Convert (Item : UTF_8_String; + Output_BOM : Boolean := False) + return UTF_16_Wide_String; + function Convert (Item : UTF_16_Wide_String; + Output_Scheme : Encoding_Scheme; + Output_BOM : Boolean := False) return UTF_String; + function Convert (Item : UTF_16_Wide_String; + Output_BOM : Boolean := False) return UTF_8_String; +end Ada.Strings.UTF_Encoding.Conversions; +package Ada.Strings.UTF_Encoding.Strings is + pragma Pure (Strings); + -- Encoding / decoding between String and various encoding schemes + function Encode (Item : String; + Output_Scheme : Encoding_Scheme; + Output_BOM : Boolean := False) return UTF_String; + function Encode (Item : String; + Output_BOM : Boolean := False) return UTF_8_String; + function Encode (Item : String; + Output_BOM : Boolean := False) + return UTF_16_Wide_String; + function Decode (Item : UTF_String; + Input_Scheme : Encoding_Scheme) return String; + function Decode (Item : UTF_8_String) return String; + function Decode (Item : UTF_16_Wide_String) return String; +end Ada.Strings.UTF_Encoding.Strings; +package Ada.Strings.UTF_Encoding.Wide_Strings is + pragma Pure (Wide_Strings); + -- Encoding / decoding between Wide_String and various encoding schemes + function Encode (Item : Wide_String; + Output_Scheme : Encoding_Scheme; + Output_BOM : Boolean := False) return UTF_String; + function Encode (Item : Wide_String; + Output_BOM : Boolean := False) return UTF_8_String; + +10/3 + +11/3 + +12/3 + +13/3 + +14/3 + +15/3 + +16/3 + +17/3 + +18/3 + +19/3 + +20/3 + +21/3 + +22/3 + +23/3 + +24/3 + +25/3 + +26/3 + +27/3 + +28/3 + +29/3 + +30/3 + +31/3 + +32/3 + +405 13 December 2012 + +String Encoding A.4.11 + + Ada Reference Manual — 2012 Edition + +33/3 + +34/3 + +35/3 + +36/3 + +37/3 + +38/3 + +39/3 + +40/3 + +41/3 + +42/3 + +43/3 + +44/3 + +45/3 + +46/3 + +47/3 + +48/3 + +49/3 + +50/3 + + function Encode (Item : Wide_String; + Output_BOM : Boolean := False) + return UTF_16_Wide_String; + function Decode (Item : UTF_String; + Input_Scheme : Encoding_Scheme) return Wide_String; + function Decode (Item : UTF_8_String) return Wide_String; + function Decode (Item : UTF_16_Wide_String) return Wide_String; +end Ada.Strings.UTF_Encoding.Wide_Strings; +package Ada.Strings.UTF_Encoding.Wide_Wide_Strings is + pragma Pure (Wide_Wide_Strings); + -- Encoding / decoding between Wide_Wide_String and various encoding schemes + function Encode (Item : Wide_Wide_String; + Output_Scheme : Encoding_Scheme; + Output_BOM : Boolean := False) return UTF_String; + function Encode (Item : Wide_Wide_String; + Output_BOM : Boolean := False) return UTF_8_String; + function Encode (Item : Wide_Wide_String; + Output_BOM : Boolean := False) + return UTF_16_Wide_String; + function Decode (Item : UTF_String; + Input_Scheme : Encoding_Scheme) return Wide_Wide_String; + function Decode (Item : UTF_8_String) return Wide_Wide_String; + function Decode (Item : UTF_16_Wide_String) return Wide_Wide_String; +end Ada.Strings.UTF_Encoding.Wide_Wide_Strings; + +The type Encoding_Scheme defines encoding schemes. UTF_8 corresponds to the UTF-8 encoding +scheme defined by Annex D of ISO/IEC 10646. UTF_16BE corresponds to the UTF-16 encoding scheme +defined by Annex C of ISO/IEC 10646 in 8 bit, big-endian order; and UTF_16LE corresponds to the UTF- +16 encoding scheme in 8 bit, little-endian order. + +The subtype UTF_String is used to represent a String of 8-bit values containing a sequence of values +encoded in one of three ways (UTF-8, UTF-16BE, or UTF-16LE). The subtype UTF_8_String is used to +represent a String of 8-bit values containing a sequence of values encoded in UTF-8. The subtype +UTF_16_Wide_String is used to represent a Wide_String of 16-bit values containing a sequence of values +encoded in UTF-16. + +The BOM_8, BOM_16BE, BOM_16LE, and BOM_16 constants correspond to values used at the start of a +string to indicate the encoding. + +Each of the Encode functions takes a String, Wide_String, or Wide_Wide_String Item parameter that is +assumed to be an array of unencoded characters. Each of the Convert functions takes a UTF_String, +UTF_8_String, or UTF_16_String Item parameter that is assumed to contain characters whose position +values correspond to a valid encoding sequence according to the encoding scheme required by the function +or specified by its Input_Scheme parameter. + +Each of the Convert and Encode functions returns a UTF_String, UTF_8_String, or UTF_16_String value +whose characters have position values that correspond to the encoding of the Item parameter according to +the encoding scheme required by the function or specified by its Output_Scheme parameter. For UTF_8, +no overlong encoding is returned. A BOM is included at the start of the returned string if the Output_BOM +parameter is set to True. The lower bound of the returned string is 1. + +51/3 + +Each of the Decode functions takes a UTF_String, UTF_8_String, or UTF_16_String Item parameter +which is assumed to contain characters whose position values correspond to a valid encoding sequence +according to the encoding scheme required by the function or specified by its Input_Scheme parameter, + +A.4.11 String Encoding + +13 December 2012 406 + + Ada Reference Manual — 2012 Edition + +and returns the corresponding String, Wide_String, or Wide_Wide_String value. The lower bound of the +returned string is 1. + +For each of the Convert and Decode functions, an initial BOM in the input that matches the expected +encoding scheme is ignored, and a different initial BOM causes Encoding_Error to be propagated. + +The exception Encoding_Error is also propagated in the following situations: + +• By a Decode function when a UTF encoded string contains an invalid encoding sequence. +• By a Decode function when the expected encoding is UTF-16BE or UTF-16LE and the input + +string has an odd length. + +• By a Decode function yielding a String when the decoding of a sequence results in a code point + +whose value exceeds 16#FF#. + +• By a Decode function yielding a Wide_String when the decoding of a sequence results in a code + +point whose value exceeds 16#FFFF#. + +• By an Encode function taking a Wide_String as input when an invalid character appears in the +input. In particular, the characters whose position is in the range 16#D800# .. 16#DFFF# are +invalid because they conflict with UTF-16 surrogate encodings, and the characters whose +position is 16#FFFE# or 16#FFFF# are also invalid because they conflict with BOM codes. + +function Encoding (Item : UTF_String; + Default : Encoding_Scheme := UTF_8) + return Encoding_Scheme; + +Inspects a UTF_String value to determine whether it starts with a BOM for UTF-8, UTF-16BE, +or UTF_16LE. If so, returns the scheme corresponding to the BOM; otherwise, returns the value +of Default. + +function Convert (Item : UTF_String; + Input_Scheme : Encoding_Scheme; + Output_Scheme : Encoding_Scheme; + Output_BOM : Boolean := False) return UTF_String; + +Returns the value of Item (originally encoded in UTF-8, UTF-16LE, or UTF-16BE as specified +by Input_Scheme) encoded in one of these three schemes as specified by Output_Scheme. + +function Convert (Item : UTF_String; + Input_Scheme : Encoding_Scheme; + Output_BOM : Boolean := False) + return UTF_16_Wide_String; + +Returns the value of Item (originally encoded in UTF-8, UTF-16LE, or UTF-16BE as specified +by Input_Scheme) encoded in UTF-16. + +function Convert (Item : UTF_8_String; + Output_BOM : Boolean := False) + return UTF_16_Wide_String; + +Returns the value of Item (originally encoded in UTF-8) encoded in UTF-16. + +function Convert (Item : UTF_16_Wide_String; + Output_Scheme : Encoding_Scheme; + Output_BOM : Boolean := False) return UTF_String; + +Returns the value of Item (originally encoded in UTF-16) encoded in UTF-8, UTF-16LE, or +UTF-16BE as specified by Output_Scheme. + +52/3 + +53/3 + +54/3 + +55/3 + +56/3 + +57/3 + +58/3 + +59/3 + +60/3 + +61/3 + +62/3 + +63/3 + +64/3 + +65/3 + +66/3 + +67/3 + +68/3 + +407 13 December 2012 + +String Encoding A.4.11 + + Ada Reference Manual — 2012 Edition + +69/3 + +70/3 + +71/3 + +72/3 + +73/3 + +74/3 + +75/3 + +76/3 + +77/3 + +78/3 + +79/3 + +80/3 + +81/3 + +82/3 + +83/3 + +84/3 + +85/3 + +86/3 + +87/3 + +88/3 + +89/3 + +90/3 + +91/3 + +92/3 + +93/3 + +94/3 + +function Convert (Item : UTF_16_Wide_String; + Output_BOM : Boolean := False) return UTF_8_String; + +Returns the value of Item (originally encoded in UTF-16) encoded in UTF-8. + +function Encode (Item : String; + Output_Scheme : Encoding_Scheme; + Output_BOM : Boolean := False) return UTF_String; + +Returns the value of Item encoded in UTF-8, UTF-16LE, or UTF-16BE as specified by +Output_Scheme. + +function Encode (Item : String; + Output_BOM : Boolean := False) return UTF_8_String; + +Returns the value of Item encoded in UTF-8. + +function Encode (Item : String; + Output_BOM : Boolean := False) return UTF_16_Wide_String; + +Returns the value of Item encoded in UTF_16. + +function Decode (Item : UTF_String; + Input_Scheme : Encoding_Scheme) return String; + +Returns the result of decoding Item, which is encoded in UTF-8, UTF-16LE, or UTF-16BE as +specified by Input_Scheme. + +function Decode (Item : UTF_8_String) return String; + +Returns the result of decoding Item, which is encoded in UTF-8. + +function Decode (Item : UTF_16_Wide_String) return String; + +Returns the result of decoding Item, which is encoded in UTF-16. + +function Encode (Item : Wide_String; + Output_Scheme : Encoding_Scheme; + Output_BOM : Boolean := False) return UTF_String; + +Returns the value of Item encoded in UTF-8, UTF-16LE, or UTF-16BE as specified by +Output_Scheme. + +function Encode (Item : Wide_String; + Output_BOM : Boolean := False) return UTF_8_String; + +Returns the value of Item encoded in UTF-8. + +function Encode (Item : Wide_String; + Output_BOM : Boolean := False) return UTF_16_Wide_String; + +Returns the value of Item encoded in UTF_16. + +function Decode (Item : UTF_String; + Input_Scheme : Encoding_Scheme) return Wide_String; + +Returns the result of decoding Item, which is encoded in UTF-8, UTF-16LE, or UTF-16BE as +specified by Input_Scheme. + +function Decode (Item : UTF_8_String) return Wide_String; + +Returns the result of decoding Item, which is encoded in UTF-8. + +function Decode (Item : UTF_16_Wide_String) return Wide_String; + +Returns the result of decoding Item, which is encoded in UTF-16. + +A.4.11 String Encoding + +13 December 2012 408 + + Ada Reference Manual — 2012 Edition + +function Encode (Item : Wide_Wide_String; + Output_Scheme : Encoding_Scheme; + Output_BOM : Boolean := False) return UTF_String; + +Returns the value of Item encoded in UTF-8, UTF-16LE, or UTF-16BE as specified by +Output_Scheme. + +function Encode (Item : Wide_Wide_String; + Output_BOM : Boolean := False) return UTF_8_String; + +Returns the value of Item encoded in UTF-8. + +function Encode (Item : Wide_Wide_String; + Output_BOM : Boolean := False) return UTF_16_Wide_String; + +Returns the value of Item encoded in UTF_16. + +function Decode (Item : UTF_String; + Input_Scheme : Encoding_Scheme) return Wide_Wide_String; + +Returns the result of decoding Item, which is encoded in UTF-8, UTF-16LE, or UTF-16BE as +specified by Input_Scheme. + +function Decode (Item : UTF_8_String) return Wide_Wide_String; + +Returns the result of decoding Item, which is encoded in UTF-8. + +function Decode (Item : UTF_16_Wide_String) return Wide_Wide_String; + +Returns the result of decoding Item, which is encoded in UTF-16. + +95/3 + +96/3 + +97/3 + +98/3 + +99/3 + +100/3 + +101/3 + +102/3 + +103/3 + +104/3 + +105/3 + +106/3 + +Implementation Advice + +If an implementation supports other encoding schemes, another similar child of Ada.Strings should be +defined. + +107/3 + +NOTES +18 A BOM (Byte-Order Mark, code position 16#FEFF#) can be included in a file or other entity to indicate the encoding; +it is skipped when decoding. Typically, only the first line of a file or other entity contains a BOM. When decoding, the +Encoding function can be called on the first line to determine the encoding; this encoding will then be used in subsequent +calls to Decode to convert all of the lines to an internal format. + +108/3 + +A.5 The Numerics Packages + +The library package Numerics is the parent of several child units that provide facilities for mathematical +computation. One child, the generic package Generic_Elementary_Functions, is defined in A.5.1, together +with nongeneric equivalents; two others, the package Float_Random and the generic package +Discrete_Random, are defined in A.5.2. Additional (optional) children are defined in Annex G, +“Numerics”. + +This paragraph was deleted. + +Static Semantics + +1 + +2/1 + +409 13 December 2012 + +String Encoding A.4.11 + + Ada Reference Manual — 2012 Edition + +3/2 + +package Ada.Numerics is + pragma Pure(Numerics); + Argument_Error : exception; + Pi : constant := + 3.14159_26535_89793_23846_26433_83279_50288_41971_69399_37511; + π : constant := Pi; + e : constant := + 2.71828_18284_59045_23536_02874_71352_66249_77572_47093_69996; +end Ada.Numerics; + +4 + +The Argument_Error exception is raised by a subprogram in a child unit of Numerics to signal that one or +more of the actual subprogram parameters are outside the domain of the corresponding mathematical +function. + +5 + +The implementation may specify the values of Pi and e to a larger number of significant digits. + +Implementation Permissions + +1 + +2 + +3 + +4 + +5 + +A.5.1 Elementary Functions + +Implementation-defined approximations to the mathematical functions known as the “elementary +functions” are provided by the subprograms in Numerics.Generic_Elementary_Functions. Nongeneric +equivalents of this generic package for each of the predefined floating point types are also provided as +children of Numerics. + +The generic library package Numerics.Generic_Elementary_Functions has the following declaration: + +Static Semantics + +generic + type Float_Type is digits <>; + +package Ada.Numerics.Generic_Elementary_Functions is + pragma Pure(Generic_Elementary_Functions); + function Sqrt (X : Float_Type'Base) return Float_Type'Base; + function Log (X : Float_Type'Base) return Float_Type'Base; + function Log (X, Base : Float_Type'Base) return Float_Type'Base; + function Exp (X : Float_Type'Base) return Float_Type'Base; + function "**" (Left, Right : Float_Type'Base) return Float_Type'Base; + function Sin (X : Float_Type'Base) return Float_Type'Base; + function Sin (X, Cycle : Float_Type'Base) return Float_Type'Base; + function Cos (X : Float_Type'Base) return Float_Type'Base; + function Cos (X, Cycle : Float_Type'Base) return Float_Type'Base; + function Tan (X : Float_Type'Base) return Float_Type'Base; + function Tan (X, Cycle : Float_Type'Base) return Float_Type'Base; + function Cot (X : Float_Type'Base) return Float_Type'Base; + function Cot (X, Cycle : Float_Type'Base) return Float_Type'Base; + +A.5 The Numerics Packages + +13 December 2012 410 + + + Ada Reference Manual — 2012 Edition + + function Arcsin (X : Float_Type'Base) return Float_Type'Base; + function Arcsin (X, Cycle : Float_Type'Base) return Float_Type'Base; + function Arccos (X : Float_Type'Base) return Float_Type'Base; + function Arccos (X, Cycle : Float_Type'Base) return Float_Type'Base; + function Arctan (Y : Float_Type'Base; + X : Float_Type'Base := 1.0) + return Float_Type'Base; + function Arctan (Y : Float_Type'Base; + X : Float_Type'Base := 1.0; + Cycle : Float_Type'Base) return Float_Type'Base; + function Arccot (X : Float_Type'Base; + Y : Float_Type'Base := 1.0) + return Float_Type'Base; + function Arccot (X : Float_Type'Base; + Y : Float_Type'Base := 1.0; + Cycle : Float_Type'Base) return Float_Type'Base; + function Sinh (X : Float_Type'Base) return Float_Type'Base; + function Cosh (X : Float_Type'Base) return Float_Type'Base; + function Tanh (X : Float_Type'Base) return Float_Type'Base; + function Coth (X : Float_Type'Base) return Float_Type'Base; + function Arcsinh (X : Float_Type'Base) return Float_Type'Base; + function Arccosh (X : Float_Type'Base) return Float_Type'Base; + function Arctanh (X : Float_Type'Base) return Float_Type'Base; + function Arccoth (X : Float_Type'Base) return Float_Type'Base; +end Ada.Numerics.Generic_Elementary_Functions; + +The library package Numerics.Elementary_Functions is declared pure and defines the same subprograms +as Numerics.Generic_Elementary_Functions, except that the predefined type Float is systematically +substituted for Float_Type'Base throughout. Nongeneric equivalents of Numerics.Generic_Elementary_- +Functions for each of the other predefined floating point types are defined similarly, with the names +Numerics.Short_Elementary_Functions, Numerics.Long_Elementary_Functions, etc. + +The functions have their usual mathematical meanings. When the Base parameter is specified, the Log +function computes the logarithm to the given base; otherwise, it computes the natural logarithm. When the +Cycle parameter is specified, the parameter X of the forward trigonometric functions (Sin, Cos, Tan, and +Cot) and the results of the inverse trigonometric functions (Arcsin, Arccos, Arctan, and Arccot) are +measured in units such that a full cycle of revolution has the given value; otherwise, they are measured in +radians. + +The computed results of the mathematically multivalued functions are rendered single-valued by the +following conventions, which are meant to imply the principal branch: + +• The results of the Sqrt and Arccosh functions and that of the exponentiation operator are + +nonnegative. + +• The result of the Arcsin function is in the quadrant containing the point (1.0, x), where x is the +value of the parameter X. This quadrant is I or IV; thus, the range of the Arcsin function is +approximately –π/2.0 to π/2.0 (–Cycle/4.0 to Cycle/4.0, if the parameter Cycle is specified). +• The result of the Arccos function is in the quadrant containing the point (x, 1.0), where x is the +value of the parameter X. This quadrant is I or II; thus, the Arccos function ranges from 0.0 to +approximately π (Cycle/2.0, if the parameter Cycle is specified). + +• The results of the Arctan and Arccot functions are in the quadrant containing the point (x, y), +where x and y are the values of the parameters X and Y, respectively. This may be any quadrant +(I through IV) when the parameter X (resp., Y) of Arctan (resp., Arccot) is specified, but it is +restricted to quadrants I and IV (resp., I and II) when that parameter is omitted. Thus, the range +when that parameter is specified is approximately –π to π (–Cycle/2.0 to Cycle/2.0, if the +parameter Cycle is specified); when omitted, the range of Arctan (resp., Arccot) is that of Arcsin + +6 + +7 + +8 + +9/1 + +10 + +11 + +12 + +13 + +14 + +15 + +411 13 December 2012 + +Elementary Functions A.5.1 + + Ada Reference Manual — 2012 Edition + +16 + +17 + +18 + +19 + +20 + +21 + +22 + +23 + +24 + +25 + +26 + +27 + +28 + +29 + +30 + +31 + +32 + +33 + +34 + +(resp., Arccos), as given above. When the point (x, y) lies on the negative x-axis, the result +approximates + +• π (resp., –π) when the sign of the parameter Y is positive (resp., negative), if + +Float_Type'Signed_Zeros is True; +• π, if Float_Type'Signed_Zeros is False. + +(In the case of the inverse trigonometric functions, in which a result lying on or near one of the axes may +not be exactly representable, the approximation inherent in computing the result may place it in an +adjacent quadrant, close to but on the wrong side of the axis.) + +Dynamic Semantics + +The exception Numerics.Argument_Error is raised, signaling a parameter value outside the domain of the +corresponding mathematical function, in the following cases: + +• by any forward or inverse trigonometric function with specified cycle, when the value of the + +parameter Cycle is zero or negative; + +• by the Log function with specified base, when the value of the parameter Base is zero, one, or + +negative; + +• by the Sqrt and Log functions, when the value of the parameter X is negative; +• by the exponentiation operator, when the value of the left operand is negative or when both + +operands have the value zero; + +• by the Arcsin, Arccos, and Arctanh functions, when the absolute value of the parameter X + +exceeds one; + +• by the Arctan and Arccot functions, when the parameters X and Y both have the value zero; +• by the Arccosh function, when the value of the parameter X is less than one; and +• by the Arccoth function, when the absolute value of the parameter X is less than one. + +The exception Constraint_Error is raised, signaling a pole of the mathematical function (analogous to +dividing by zero), in the following cases, provided that Float_Type'Machine_Overflows is True: + +• by the Log, Cot, and Coth functions, when the value of the parameter X is zero; +• by the exponentiation operator, when the value of the left operand is zero and the value of the + +exponent is negative; + +• by the Tan function with specified cycle, when the value of the parameter X is an odd multiple + +of the quarter cycle; + +• by the Cot function with specified cycle, when the value of the parameter X is zero or a multiple + +of the half cycle; and + +• by the Arctanh and Arccoth functions, when the absolute value of the parameter X is one. + +Constraint_Error can also be raised when a finite result overflows (see G.2.4); this may occur for +parameter values sufficiently near poles, and, in the case of some of the functions, for parameter values +with sufficiently large magnitudes. When Float_Type'Machine_Overflows is False, the result at poles is +unspecified. + +35 + +When one parameter of a function with multiple parameters represents a pole and another is outside the +function's domain, the latter takes precedence (i.e., Numerics.Argument_Error is raised). + +A.5.1 Elementary Functions + +13 December 2012 412 + + Ada Reference Manual — 2012 Edition + +Implementation Requirements + +In the implementation of Numerics.Generic_Elementary_Functions, the range of intermediate values +allowed during the calculation of a final result shall not be affected by any range constraint of the subtype +Float_Type. + +In the following cases, evaluation of an elementary function shall yield the prescribed result, provided that +the preceding rules do not call for an exception to be raised: + +• When the parameter X has the value zero, the Sqrt, Sin, Arcsin, Tan, Sinh, Arcsinh, Tanh, and +Arctanh functions yield a result of zero, and the Exp, Cos, and Cosh functions yield a result of +one. + +• When the parameter X has the value one, the Sqrt function yields a result of one, and the Log, + +Arccos, and Arccosh functions yield a result of zero. + +• When the parameter Y has the value zero and the parameter X has a positive value, the Arctan + +and Arccot functions yield a result of zero. + +• The results of the Sin, Cos, Tan, and Cot functions with specified cycle are exact when the +mathematical result is zero; those of the first two are also exact when the mathematical result is +± 1.0. + +• Exponentiation by a zero exponent yields the value one. Exponentiation by a unit exponent +yields the value of the left operand. Exponentiation of the value one yields the value one. +Exponentiation of the value zero yields the value zero. + +Other accuracy requirements for the elementary functions, which apply only in implementations +conforming to the Numerics Annex, and then only in the “strict” mode defined there (see G.2), are given +in G.2.4. + +When Float_Type'Signed_Zeros is True, the sign of a zero result shall be as follows: + +• A prescribed zero result delivered at the origin by one of the odd functions (Sin, Arcsin, Sinh, +Arcsinh, Tan, Arctan or Arccot as a function of Y when X is fixed and positive, Tanh, and +Arctanh) has the sign of the parameter X (Y, in the case of Arctan or Arccot). + +• A prescribed zero result delivered by one of the odd functions away from the origin, or by some + +other elementary function, has an implementation-defined sign. + +• A zero result that is not a prescribed result (i.e., one that results from rounding or underflow) has + +the correct mathematical sign. + +The nongeneric equivalent packages may, but need not, be actual instantiations of the generic package for +the appropriate predefined type. + +Implementation Permissions + +A.5.2 Random Number Generation + +Facilities for the generation of pseudo-random floating point numbers are provided in the package +Numerics.Float_Random; the generic package Numerics.Discrete_Random provides similar facilities for +the generation of pseudo-random integers and pseudo-random values of enumeration types. For brevity, +pseudo-random values of any of these types are called random numbers. + +Some of the facilities provided are basic to all applications of random numbers. These include a limited +private type each of whose objects serves as the generator of a (possibly distinct) sequence of random +numbers; a function to obtain the “next” random number from a given sequence of random numbers (that + +36 + +37 + +38 + +39 + +40 + +41 + +42 + +43 + +44 + +45 + +46 + +47 + +48 + +1 + +2 + +413 13 December 2012 + +Elementary Functions A.5.1 + + Ada Reference Manual — 2012 Edition + +is, from its generator); and subprograms to initialize or reinitialize a given generator to a time-dependent +state or a state denoted by a single integer. + +Other facilities are provided specifically for advanced applications. These include subprograms to save +and restore the state of a given generator; a private type whose objects can be used to hold the saved state +of a generator; and subprograms to obtain a string representation of a given generator state, or, given such +a string representation, the corresponding state. + +The library package Numerics.Float_Random has the following declaration: + +Static Semantics + +package Ada.Numerics.Float_Random is + -- Basic facilities + type Generator is limited private; + subtype Uniformly_Distributed is Float range 0.0 .. 1.0; + function Random (Gen : Generator) return Uniformly_Distributed; + procedure Reset (Gen : in Generator; + Initiator : in Integer); + procedure Reset (Gen : in Generator); + -- Advanced facilities + type State is private; + procedure Save (Gen : in Generator; + To_State : out State); + procedure Reset (Gen : in Generator; + From_State : in State); + Max_Image_Width : constant := implementation-defined integer value; + function Image (Of_State : State) return String; + function Value (Coded_State : String) return State; +private + ... -- not specified by the language +end Ada.Numerics.Float_Random; + +3 + +4 + +5 + +6 + +7 + +8 + +9 + +10 + +11 + +12 + +13 + +14 + +15 + +15.1/2 + +The type Generator needs finalization (see 7.6). + +16 + +17 + +18 + +19 + +20 + +21 + +22 + +23 + +24 + +25 + +26 + +The generic library package Numerics.Discrete_Random has the following declaration: + +generic + type Result_Subtype is (<>); +package Ada.Numerics.Discrete_Random is + -- Basic facilities + type Generator is limited private; + function Random (Gen : Generator) return Result_Subtype; + procedure Reset (Gen : in Generator; + Initiator : in Integer); + procedure Reset (Gen : in Generator); + -- Advanced facilities + type State is private; + procedure Save (Gen : in Generator; + To_State : out State); + procedure Reset (Gen : in Generator; + From_State : in State); + Max_Image_Width : constant := implementation-defined integer value; + function Image (Of_State : State) return String; + function Value (Coded_State : String) return State; + +A.5.2 Random Number Generation + +13 December 2012 414 + + + Ada Reference Manual — 2012 Edition + +private + ... -- not specified by the language +end Ada.Numerics.Discrete_Random; + +The type Generator needs finalization (see 7.6) in every instantiation of Numerics.Discrete_Random. + +An object of the limited private type Generator is associated with a sequence of random numbers. Each +generator has a hidden (internal) state, which the operations on generators use to determine the position in +the associated sequence. All generators are implicitly initialized to an unspecified state that does not vary +from one program execution to another; they may also be explicitly initialized, or reinitialized, to a time- +dependent state, to a previously saved state, or to a state uniquely denoted by an integer value. + +27 + +27.1/2 + +28 + +An object of the private type State can be used to hold the internal state of a generator. Such objects are +only needed if the application is designed to save and restore generator states or to examine or +manufacture them. The implicit initial value of type State corresponds to the implicit initial value of all +generators. + +29/3 + +The operations on generators affect the state and therefore the future values of the associated sequence. +The semantics of the operations on generators and states are defined below. + +function Random (Gen : Generator) return Uniformly_Distributed; +function Random (Gen : Generator) return Result_Subtype; + +to an + +implementation-defined algorithm. The + +Obtains the “next” random number from the given generator, relative to its current state, +according +in +Numerics.Float_Random is delivered as a value of the subtype Uniformly_Distributed, which is +a subtype of the predefined type Float having a range of 0.0 .. 1.0. The result of the function in +an instantiation of Numerics.Discrete_Random is delivered as a value of the generic formal +subtype Result_Subtype. + +result of + +function + +the + +procedure Reset (Gen : in Generator; + Initiator : in Integer); +procedure Reset (Gen : in Generator); + +Sets the state of the specified generator to one that is an unspecified function of the value of the +parameter Initiator (or to a time-dependent state, if only a generator parameter is specified). The +latter form of the procedure is known as the time-dependent Reset procedure. + +procedure Save (Gen : in Generator; + To_State : out State); +procedure Reset (Gen : in Generator; + From_State : in State); + +Save obtains the current state of a generator. Reset gives a generator the specified state. A +generator that is reset to a state previously obtained by invoking Save is restored to the state it +had when Save was invoked. + +function Image (Of_State : State) return String; +function Value (Coded_State : String) return State; + +Image provides a representation of a state coded (in an implementation-defined way) as a string +whose length is bounded by the value of Max_Image_Width. Value is the inverse of Image: +Value(Image(S)) = S for each state S that can be obtained from a generator by invoking Save. + +Instantiation of Numerics.Discrete_Random with a subtype having a null range raises Constraint_Error. + +Dynamic Semantics + +This paragraph was deleted. + +415 13 December 2012 + +Random Number Generation A.5.2 + +30 + +31 + +32 + +33 + +34 + +35 + +36 + +37 + +38 + +39 + +40/1 + + Ada Reference Manual — 2012 Edition + +Bounded (Run-Time) Errors + +40.1/1 + +It is a bounded error to invoke Value with a string that is not the image of any generator state. If the error +is detected, Constraint_Error or Program_Error is raised. Otherwise, a call to Reset with the resulting state +will produce a generator such that calls to Random with this generator will produce a sequence of values +of the appropriate subtype, but which might not be random in character. That is, the sequence of values +might not fulfill the implementation requirements of this subclause. + +41 + +42 + +43 + +44 + +45 + +46 + +47 + +48 + +49 + +50 + +Implementation Requirements + +A sufficiently long sequence of random numbers obtained by successive calls to Random is approximately +uniformly distributed over the range of the result subtype. + +The Random function in an instantiation of Numerics.Discrete_Random is guaranteed to yield each value +in its result subtype in a finite number of calls, provided that the number of such values does not exceed 2 +15. + +Other performance requirements for the random number generator, which apply only in implementations +conforming to the Numerics Annex, and then only in the “strict” mode defined there (see G.2), are given +in G.2.5. + +Documentation Requirements + +No one algorithm for random number generation is best for all applications. To enable the user to +determine the suitability of the random number generators for the intended application, the implementation +shall describe the algorithm used and shall give its period, if known exactly, or a lower bound on the +period, if the exact period is unknown. Periods that are so long that the periodicity is unobservable in +practice can be described in such terms, without giving a numerical bound. + +The implementation also shall document the minimum time interval between calls to the time-dependent +Reset procedure that are guaranteed to initiate different sequences, and it shall document the nature of the +strings that Value will accept without raising Constraint_Error. + +Implementation Advice + +Any storage associated with an object of type Generator should be reclaimed on exit from the scope of the +object. + +If the generator period is sufficiently long in relation to the number of distinct initiator values, then each +possible value of Initiator passed to Reset should initiate a sequence of random numbers that does not, in a +practical sense, overlap the sequence initiated by any other value. If this is not possible, then the mapping +between initiator values and generator states should be a rapidly varying function of the initiator value. + +NOTES +19 If two or more tasks are to share the same generator, then the tasks have to synchronize their access to the generator as +for any shared variable (see 9.10). + +20 Within a given implementation, a repeatable random number sequence can be obtained by relying on the implicit +initialization of generators or by explicitly initializing a generator with a repeatable initiator value. Different sequences of +random numbers can be obtained from a given generator in different program executions by explicitly initializing the +generator to a time-dependent state. + +21 A given implementation of the Random function in Numerics.Float_Random may or may not be capable of delivering +the values 0.0 or 1.0. Portable applications should assume that these values, or values sufficiently close to them to behave +indistinguishably from them, can occur. If a sequence of random integers from some fixed range is needed, the application +should use the Random function in an appropriate instantiation of Numerics.Discrete_Random, rather than transforming +the result of the Random function in Numerics.Float_Random. However, some applications with unusual requirements, +such as for a sequence of random integers each drawn from a different range, will find it more convenient to transform the +result of the floating point Random function. For M ≥ 1, the expression + +A.5.2 Random Number Generation + +13 December 2012 416 + + 51 + +52 + +53/2 + +54 + +55 + +56 + +57 + +58 + +Ada Reference Manual — 2012 Edition + + Integer(Float(M) * Random(G)) mod M + +transforms the result of Random(G) to an integer uniformly distributed over the range 0 .. M–1; it is valid even if Random +delivers 0.0 or 1.0. Each value of the result range is possible, provided that M is not too large. Exponentially distributed +(floating point) random numbers with mean and standard deviation 1.0 can be obtained by the transformation + + -Log(Random(G) + Float'Model_Small) + +where Log comes from Numerics.Elementary_Functions (see A.5.1); +the addition of +Float'Model_Small avoids the exception that would be raised were Log to be given the value zero, without affecting the +result (in most implementations) when Random returns a nonzero value. + +this expression, + +in + +Examples + +Example of a program that plays a simulated dice game: +with Ada.Numerics.Discrete_Random; +procedure Dice_Game is + subtype Die is Integer range 1 .. 6; + subtype Dice is Integer range 2*Die'First .. 2*Die'Last; + package Random_Die is new Ada.Numerics.Discrete_Random (Die); + use Random_Die; + G : Generator; + D : Dice; +begin + Reset (G); -- Start the generator in a unique state in each run + loop + -- Roll a pair of dice; sum and process the results + D := Random(G) + Random(G); + ... + end loop; +end Dice_Game; + +Example of a program that simulates coin tosses: +with Ada.Numerics.Discrete_Random; +procedure Flip_A_Coin is + type Coin is (Heads, Tails); + package Random_Coin is new Ada.Numerics.Discrete_Random (Coin); + use Random_Coin; + G : Generator; +begin + Reset (G); -- Start the generator in a unique state in each run + loop + -- Toss a coin and process the result + case Random(G) is + when Heads => + ... + when Tails => + ... + end case; + ... + end loop; +end Flip_A_Coin; + +417 13 December 2012 + +Random Number Generation A.5.2 + + 59 + +60 + +61 + +1 + +2 + +3 + +4 + +5 + +6 + +Ada Reference Manual — 2012 Edition + +Example of a parallel simulation of a physical system, with a separate generator of event probabilities in +each task: + +with Ada.Numerics.Float_Random; +procedure Parallel_Simulation is + use Ada.Numerics.Float_Random; + task type Worker is + entry Initialize_Generator (Initiator : in Integer); + ... + end Worker; + W : array (1 .. 10) of Worker; + task body Worker is + G : Generator; + Probability_Of_Event : Uniformly_Distributed; + begin + accept Initialize_Generator (Initiator : in Integer) do + Reset (G, Initiator); + end Initialize_Generator; + loop + ... + Probability_Of_Event := Random(G); + ... + end loop; + end Worker; +begin + -- Initialize the generators in the Worker tasks to different states + for I in W'Range loop + W(I).Initialize_Generator (I); + end loop; + ... -- Wait for the Worker tasks to terminate +end Parallel_Simulation; + +NOTES +22 Notes on the last example: Although each Worker task initializes its generator to a different state, those states will be +the same in every execution of the program. The generator states can be initialized uniquely in each program execution by +instantiating Ada.Numerics.Discrete_Random for the type Integer in the main procedure, resetting the generator obtained +from that instance to a time-dependent state, and then using random integers obtained from that generator to initialize the +generators in each Worker task. + +A.5.3 Attributes of Floating Point Types + +Static Semantics + +The following representation-oriented attributes are defined for every subtype S of a floating point type T. + +S'Machine_Radix + +Yields the radix of the hardware representation of the type T. The value of this attribute is +of the type universal_integer. + +The values of other representation-oriented attributes of a floating point subtype, and of the “primitive +function” attributes of a floating point subtype described later, are defined in terms of a particular +representation of nonzero values called the canonical form. The canonical form (for the type T) is the form + ± mantissa · T'Machine_Radixexponent +where + +• mantissa is a fraction in the number base T'Machine_Radix, the first digit of which is nonzero, + +and + +• exponent is an integer. + +S'Machine_Mantissa + +Yields the largest value of p such that every value expressible in the canonical form (for the +type T), having a p-digit mantissa and an exponent between T'Machine_Emin and + +A.5.2 Random Number Generation + +13 December 2012 418 + + + + Ada Reference Manual — 2012 Edition + +T'Machine_Emax, is a machine number (see 3.5.7) of the type T. This attribute yields a +value of the type universal_integer. + +S'Machine_Emin + +Yields the smallest (most negative) value of exponent such that every value expressible in +the canonical form (for the type T), having a mantissa of T'Machine_Mantissa digits, is a +machine number (see 3.5.7) of the type T. This attribute yields a value of the type +universal_integer. + +S'Machine_Emax + +S'Denorm + +Yields the largest (most positive) value of exponent such that every value expressible in the +canonical form (for the type T), having a mantissa of T'Machine_Mantissa digits, is a +machine number (see 3.5.7) of the type T. This attribute yields a value of the type +universal_integer. + +Yields the value True if every value expressible in the form + ± mantissa · T'Machine_RadixT'Machine_Emin +where mantissa is a nonzero T'Machine_Mantissa-digit fraction in the number base +T'Machine_Radix, the first digit of which is zero, is a machine number (see 3.5.7) of the +type T; yields the value False otherwise. The value of this attribute is of the predefined type +Boolean. + +The values described by the formula in the definition of S'Denorm are called denormalized numbers. A +nonzero machine number that is not a denormalized number is a normalized number. A normalized +number x of a given type T is said to be represented in canonical form when it is expressed in the +canonical form (for the type T) with a mantissa having T'Machine_Mantissa digits; the resulting form is +the canonical-form representation of x. + +S'Machine_Rounds + +Yields the value True if rounding is performed on inexact results of every predefined +operation that yields a result of the type T; yields the value False otherwise. The value of +this attribute is of the predefined type Boolean. + +S'Machine_Overflows + +Yields the value True if overflow and divide-by-zero are detected and reported by raising +Constraint_Error for every predefined operation that yields a result of the type T; yields the +value False otherwise. The value of this attribute is of the predefined type Boolean. + +S'Signed_Zeros + +Yields the value True if the hardware representation for the type T has the capability of +representing both positively and negatively signed zeros, these being generated and used by +the predefined operations of the type T as specified in IEC 559:1989; yields the value False +otherwise. The value of this attribute is of the predefined type Boolean. + +For every value x of a floating point type T, the normalized exponent of x is defined as follows: + +the normalized exponent of zero is (by convention) zero; + +• +• for nonzero x, the normalized exponent of x is the unique integer k such that T'Machine_Radixk–1 + +≤ |x| < T'Machine_Radixk. + +The following primitive function attributes are defined for any subtype S of a floating point type T. + +S'Exponent + +S'Exponent denotes a function with the following specification: + +function S'Exponent (X : T) + return universal_integer + +The function yields the normalized exponent of X. + +419 13 December 2012 + +Attributes of Floating Point Types A.5.3 + +7 + +8 + +9 + +10 + +11 + +12 + +13 + +14 + +15 + +16 + +17 + +18 + +19 + +20 + + + + + + + + + + Ada Reference Manual — 2012 Edition + +21 + +22 + +23 + +24 + +25 + +26 + +27 + +28 + +29 + +30 + +31 + +32 + +33 + +34 + +35 + +36 + +37 + +38 + +S'Fraction + +S'Fraction denotes a function with the following specification: + +function S'Fraction (X : T) + return T + +The function yields the value X · T'Machine_Radix–k, where k is the normalized exponent of +X. A zero result, which can only occur when X is zero, has the sign of X. + +S'Compose + +S'Compose denotes a function with the following specification: + +function S'Compose (Fraction : T; + Exponent : universal_integer) + return T + +Let v be the value Fraction · T'Machine_RadixExponent–k, where k is the normalized exponent +of Fraction. If v is a machine number of the type T, or if |v| ≥ T'Model_Small, the function +yields v; otherwise, it yields either one of the machine numbers of the type T adjacent to v. +Constraint_Error is optionally raised if v is outside the base range of S. A zero result has the +sign of Fraction when S'Signed_Zeros is True. + +S'Scaling + +S'Scaling denotes a function with the following specification: + +function S'Scaling (X : T; + Adjustment : universal_integer) + return T + +Let v be the value X · T'Machine_RadixAdjustment. If v is a machine number of the type T, or if +|v| ≥ T'Model_Small, the function yields v; otherwise, it yields either one of the machine +numbers of the type T adjacent to v. Constraint_Error is optionally raised if v is outside the +base range of S. A zero result has the sign of X when S'Signed_Zeros is True. + +S'Floor + +S'Floor denotes a function with the following specification: + +function S'Floor (X : T) + return T + +The function yields the value X, i.e., the largest (most positive) integral value less than or +equal to X. When X is zero, the result has the sign of X; a zero result otherwise has a +positive sign. + +S'Ceiling + +S'Ceiling denotes a function with the following specification: + +function S'Ceiling (X : T) + return T + +The function yields the value X, i.e., the smallest (most negative) integral value greater +than or equal to X. When X is zero, the result has the sign of X; a zero result otherwise has a +negative sign when S'Signed_Zeros is True. + +S'Rounding S'Rounding denotes a function with the following specification: + +function S'Rounding (X : T) + return T + +The function yields the integral value nearest to X, rounding away from zero if X lies +exactly halfway between two integers. A zero result has the sign of X when S'Signed_Zeros +is True. + +39 + +S'Unbiased_Rounding + +40 + +41 + +S'Unbiased_Rounding denotes a function with the following specification: + +function S'Unbiased_Rounding (X : T) + return T + +The function yields the integral value nearest to X, rounding toward the even integer if X +lies exactly halfway between two integers. A zero result has the sign of X when +S'Signed_Zeros is True. + +A.5.3 Attributes of Floating Point Types + +13 December 2012 420 + + + + + + + + + + Ada Reference Manual — 2012 Edition + +S'Machine_Rounding + +S'Machine_Rounding denotes a function with the following specification: + +function S'Machine_Rounding (X : T) + return T + +The function yields the integral value nearest to X. If X lies exactly halfway between two +integers, one of those integers is returned, but which of them is returned is unspecified. A +zero result has the sign of X when S'Signed_Zeros is True. This function provides access to +the rounding behavior which is most efficient on the target processor. + +S'Truncation S'Truncation denotes a function with the following specification: +function S'Truncation (X : T) + return T + +The function yields the value X when X is negative, and X otherwise. A zero result has +the sign of X when S'Signed_Zeros is True. + +S'Remainder S'Remainder denotes a function with the following specification: +function S'Remainder (X, Y : T) + return T + +For nonzero Y, let v be the value X – n · Y, where n is the integer nearest to the exact value +of X/Y; if |n – X/Y| = 1/2, then n is chosen to be even. If v is a machine number of the type +T, the function yields v; otherwise, it yields zero. Constraint_Error is raised if Y is zero. A +zero result has the sign of X when S'Signed_Zeros is True. + +S'Adjacent + +S'Adjacent denotes a function with the following specification: + +function S'Adjacent (X, Towards : T) + return T + +If Towards = X, the function yields X; otherwise, it yields the machine number of the type T +adjacent to X in the direction of Towards, if that machine number exists. If the result would +be outside the base range of S, Constraint_Error is raised. When T'Signed_Zeros is True, a +zero result has the sign of X. When Towards is zero, its sign has no bearing on the result. + +S'Copy_Sign S'Copy_Sign denotes a function with the following specification: + +function S'Copy_Sign (Value, Sign : T) + return T + +If the value of Value is nonzero, the function yields a result whose magnitude is that of +Value and whose sign is that of Sign; otherwise, it yields the value zero. Constraint_Error is +optionally raised if the result is outside the base range of S. A zero result has the sign of +Sign when S'Signed_Zeros is True. + +S'Leading_Part + +S'Leading_Part denotes a function with the following specification: + +function S'Leading_Part (X : T; + Radix_Digits : universal_integer) + return T + +Let v be the value T'Machine_Radixk–Radix_Digits, where k is the normalized exponent of X. The +function yields the value + +• X/v · v, when X is nonnegative and Radix_Digits is positive; +• X/v · v, when X is negative and Radix_Digits is positive. + +Constraint_Error is raised when Radix_Digits is zero or negative. A zero result, which can +only occur when X is zero, has the sign of X. + +S'Machine + +S'Machine denotes a function with the following specification: + +41.1/2 + +41.2/2 + +41.3/2 + +42 + +43 + +44 + +45 + +46 + +47 + +48 + +49 + +50 + +51 + +52 + +53 + +54 + +55 + +56 + +57 + +58 + +59 + +60 + +421 13 December 2012 + +Attributes of Floating Point Types A.5.3 + + + + + + + + + + + 61 + +62 + +63 + +64 + +Ada Reference Manual — 2012 Edition + +function S'Machine (X : T) + return T + +If X is a machine number of the type T, the function yields X; otherwise, it yields the value +obtained by rounding or truncating X to either one of the adjacent machine numbers of the +type T. Constraint_Error is raised if rounding or truncating X to the precision of the +machine numbers results in a value outside the base range of S. A zero result has the sign of +X when S'Signed_Zeros is True. + +The following model-oriented attributes are defined for any subtype S of a floating point type T. + +S'Model_Mantissa + +If the Numerics Annex is not supported, this attribute yields an implementation defined +value that is greater than or equal to d · log(10) / log(T'Machine_Radix) + 1, where d is +the requested decimal precision of T, and less than or equal to the value of +T'Machine_Mantissa. See G.2.2 for further requirements that apply to implementations +supporting the Numerics Annex. The value of this attribute is of the type universal_integer. + +65 + +S'Model_Emin + +If the Numerics Annex is not supported, this attribute yields an implementation defined +value that is greater than or equal to the value of T'Machine_Emin. See G.2.2 for further +requirements that apply to implementations supporting the Numerics Annex. The value of +this attribute is of the type universal_integer. + +66 + +S'Model_Epsilon + +Yields the value T'Machine_Radix1 – T'Model_Mantissa. The value of this attribute is of the type +universal_real. + +67 + +S'Model_Small + +Yields the value T'Machine_RadixT'Model_Emin – 1. The value of this attribute is of the type +universal_real. + +S'Model + +S'Model denotes a function with the following specification: + +function S'Model (X : T) + return T + +If the Numerics Annex is not supported, the meaning of this attribute is implementation +defined; see G.2.2 for the definition that applies to implementations supporting the +Numerics Annex. + +Yields the lower bound of the safe range (see 3.5.7) of the type T. If the Numerics Annex is +not supported, the value of this attribute is implementation defined; see G.2.2 for the +definition that applies to implementations supporting the Numerics Annex. The value of +this attribute is of the type universal_real. + +68 + +69 + +70 + +71 + +S'Safe_First + +72 + +S'Safe_Last Yields the upper bound of the safe range (see 3.5.7) of the type T. If the Numerics Annex is +not supported, the value of this attribute is implementation defined; see G.2.2 for the +definition that applies to implementations supporting the Numerics Annex. The value of +this attribute is of the type universal_real. + +A.5.4 Attributes of Fixed Point Types + +Static Semantics + +1 + +The following representation-oriented attributes are defined for every subtype S of a fixed point type T. + +A.5.3 Attributes of Floating Point Types + +13 December 2012 422 + + + + + + + + + Ada Reference Manual — 2012 Edition + +S'Machine_Radix + +Yields the radix of the hardware representation of the type T. The value of this attribute is +of the type universal_integer. + +S'Machine_Rounds + +Yields the value True if rounding is performed on inexact results of every predefined +operation that yields a result of the type T; yields the value False otherwise. The value of +this attribute is of the predefined type Boolean. + +S'Machine_Overflows + +Yields the value True if overflow and divide-by-zero are detected and reported by raising +Constraint_Error for every predefined operation that yields a result of the type T; yields the +value False otherwise. The value of this attribute is of the predefined type Boolean. + +A.6 Input-Output + +Input-output is provided through language-defined packages, each of which is a child of the root package +Ada. The generic packages Sequential_IO and Direct_IO define input-output operations applicable to files +containing elements of a given type. The generic package Storage_IO supports reading from and writing to +an in-memory buffer. Additional operations for text input-output are supplied in the packages Text_IO, +Wide_Text_IO, and Wide_Wide_Text_IO. Heterogeneous input-output is provided through the child +packages Streams.Stream_IO and Text_IO.Text_Streams (see also 13.13). The package IO_Exceptions +defines the exceptions needed by the predefined input-output packages. + +A.7 External Files and File Objects + +Static Semantics + +Values input from the external environment of the program, or output to the external environment, are +considered to occupy external files. An external file can be anything external to the program that can +produce a value to be read or receive a value to be written. An external file is identified by a string (the +name). A second string (the form) gives further system-dependent characteristics that may be associated +with the file, such as the physical organization or access rights. The conventions governing the +interpretation of such strings shall be documented. + +Input and output operations are expressed as operations on objects of some file type, rather than directly in +terms of the external files. In the remainder of this clause, the term file is always used to refer to a file +object; the term external file is used otherwise. + +Input-output for sequential files of values of a single element type is defined by means of the generic +package Sequential_IO. In order to define sequential input-output for a given element type, an +instantiation of this generic unit, with the given type as actual parameter, has to be declared. The resulting +package contains the declaration of a file type (called File_Type) for files of such elements, as well as the +operations applicable to these files, such as the Open, Read, and Write procedures. + +Input-output for direct access files is likewise defined by a generic package called Direct_IO. Input-output +in human-readable form is defined by the (nongeneric) packages Text_IO for Character and String data, +for +Wide_Text_IO +Wide_Wide_Character and Wide_Wide_String data. Input-output for files containing streams of elements +representing values of possibly different types is defined by means of the (nongeneric) package +Streams.Stream_IO. + +and Wide_Wide_Text_IO + +and Wide_String data, + +for Wide_Character + +2 + +3 + +4 + +1/2 + +1 + +2/3 + +3 + +4/2 + +423 13 December 2012 + +Attributes of Fixed Point Types A.5.4 + + + + + Ada Reference Manual — 2012 Edition + +5 + +6 + +7 + +8 + +9 + +10/2 + +11 + +12 + +13/2 + +14/3 + +15/2 + +16 + +1/2 + +2 + +Before input or output operations can be performed on a file, the file first has to be associated with an +external file. While such an association is in effect, the file is said to be open, and otherwise the file is said +to be closed. + +The language does not define what happens to external files after the completion of the main program and +all the library tasks (in particular, if corresponding files have not been closed). The effect of input-output +for access types is unspecified. + +An open file has a current mode, which is a value of one of the following enumeration types: +type File_Mode is (In_File, Inout_File, Out_File); -- for Direct_IO + +These values correspond respectively to the cases where only reading, both reading and writing, +or only writing are to be performed. + +type File_Mode is (In_File, Out_File, Append_File); +-- for Sequential_IO, Text_IO, Wide_Text_IO, Wide_Wide_Text_IO, and Stream_IO + +These values correspond respectively to the cases where only reading, only writing, or only +appending are to be performed. + +The mode of a file can be changed. + +Several file management operations are common to Sequential_IO, Direct_IO, Text_IO, Wide_Text_IO, +and Wide_Wide_Text_IO. These operations are described in subclause A.8.2 for sequential and direct +files. Any additional effects concerning text input-output are described in subclause A.10.2. + +The exceptions that can be propagated by the execution of an input-output subprogram are defined in the +package IO_Exceptions; the situations in which they can be propagated are described following the +description of the subprogram (and in subclause A.13). The exceptions Storage_Error and Program_Error +may be propagated. (Program_Error can only be propagated due to errors made by the caller of the +subprogram.) Finally, exceptions can be propagated in certain implementation-defined situations. + +NOTES +23 Each instantiation of the generic packages Sequential_IO and Direct_IO declares a different type File_Type. In the +case of Text_IO, Wide_Text_IO, Wide_Wide_Text_IO, and Streams.Stream_IO, the corresponding type File_Type is +unique. + +24 A bidirectional device can often be modeled as two sequential files associated with the device, one of mode In_File, +and one of mode Out_File. An implementation may restrict the number of files that may be associated with a given +external file. + +A.8 Sequential and Direct Files + +Static Semantics + +Two kinds of access to external files are defined in this subclause: sequential access and direct access. +The corresponding file types and the associated operations are provided by the generic packages +Sequential_IO and Direct_IO. A file object to be used for sequential access is called a sequential file, and +one to be used for direct access is called a direct file. Access to stream files is described in A.12.1. + +For sequential access, the file is viewed as a sequence of values that are transferred in the order of their +appearance (as produced by the program or by the external environment). When the file is opened with +mode In_File or Out_File, transfer starts respectively from or to the beginning of the file. When the file is +opened with mode Append_File, transfer to the file starts after the last element of the file. + +A.7 External Files and File Objects + +13 December 2012 424 + + Ada Reference Manual — 2012 Edition + +For direct access, the file is viewed as a set of elements occupying consecutive positions in linear order; a +value can be transferred to or from an element of the file at any selected position. The position of an +element is specified by its index, which is a number, greater than zero, of the implementation-defined +integer type Count. The first element, if any, has index one; the index of the last element, if any, is called +the current size; the current size is zero if there are no elements. The current size is a property of the +external file. + +An open direct file has a current index, which is the index that will be used by the next read or write +operation. When a direct file is opened, the current index is set to one. The current index of a direct file is +a property of a file object, not of an external file. + +A.8.1 The Generic Package Sequential_IO + +The generic library package Sequential_IO has the following declaration: + +Static Semantics + +with Ada.IO_Exceptions; +generic + type Element_Type(<>) is private; +package Ada.Sequential_IO is + type File_Type is limited private; + type File_Mode is (In_File, Out_File, Append_File); + -- File management + procedure Create(File : in out File_Type; + Mode : in File_Mode := Out_File; + Name : in String := ""; + Form : in String := ""); + procedure Open (File : in out File_Type; + Mode : in File_Mode; + Name : in String; + Form : in String := ""); + procedure Close (File : in out File_Type); + procedure Delete(File : in out File_Type); + procedure Reset (File : in out File_Type; Mode : in File_Mode); + procedure Reset (File : in out File_Type); + function Mode (File : in File_Type) return File_Mode; + function Name (File : in File_Type) return String; + function Form (File : in File_Type) return String; + function Is_Open(File : in File_Type) return Boolean; + -- Input and output operations + procedure Read (File : in File_Type; Item : out Element_Type); + procedure Write (File : in File_Type; Item : in Element_Type); + function End_Of_File(File : in File_Type) return Boolean; + -- Exceptions + Status_Error : exception renames IO_Exceptions.Status_Error; + Mode_Error : exception renames IO_Exceptions.Mode_Error; + Name_Error : exception renames IO_Exceptions.Name_Error; + Use_Error : exception renames IO_Exceptions.Use_Error; + Device_Error : exception renames IO_Exceptions.Device_Error; + End_Error : exception renames IO_Exceptions.End_Error; + Data_Error : exception renames IO_Exceptions.Data_Error; +private + ... -- not specified by the language +end Ada.Sequential_IO; + +3 + +4 + +1 + +2 + +3 + +4 + +5 + +6 + +7 + +8 + +9 + +10 + +11 + +12 + +13 + +14 + +15 + +16 + +425 13 December 2012 + +Sequential and Direct Files A.8 + + Ada Reference Manual — 2012 Edition + +17/2 + +The type File_Type needs finalization (see 7.6) in every instantiation of Sequential_IO. + +1 + +2 + +3/2 + +4 + +5 + +6 + +7 + +8 + +9 + +10 + +A.8.2 File Management + +Static Semantics + +The procedures and functions described in this subclause provide for the control of external files; their +declarations are repeated in each of the packages for sequential, direct, text, and stream input-output. For +text input-output, the procedures Create, Open, and Reset have additional effects described in subclause +A.10.2. + +procedure Create(File : in out File_Type; + Mode : in File_Mode := default_mode; + Name : in String := ""; + Form : in String := ""); + +Establishes a new external file, with the given name and form, and associates this external file +with the given file. The given file is left open. The current mode of the given file is set to the +given access mode. The default access mode is the mode Out_File for sequential, stream, and +text input-output; it is the mode Inout_File for direct input-output. For direct access, the size of +the created file is implementation defined. + +A null string for Name specifies an external file that is not accessible after the completion of the +main program (a temporary file). A null string for Form specifies the use of the default options +of the implementation for the external file. + +The exception Status_Error is propagated if the given file is already open. The exception +Name_Error is propagated if the string given as Name does not allow the identification of an +external file. The exception Use_Error is propagated if, for the specified mode, the external +environment does not support creation of an external file with the given name (in the absence of +Name_Error) and form. + +procedure Open(File : in out File_Type; + Mode : in File_Mode; + Name : in String; + Form : in String := ""); + +Associates the given file with an existing external file having the given name and form, and sets +the current mode of the given file to the given mode. The given file is left open. + +The exception Status_Error is propagated if the given file is already open. The exception +Name_Error is propagated if the string given as Name does not allow the identification of an +external file; in particular, this exception is propagated if no external file with the given name +exists. The exception Use_Error is propagated if, for the specified mode, the external +environment does not support opening for an external file with the given name (in the absence of +Name_Error) and form. + +procedure Close(File : in out File_Type); + +Severs the association between the given file and its associated external file. The given file is +left closed. In addition, for sequential files, if the file being closed has mode Out_File or +Append_File, then the last element written since the most recent open or reset is the last element +that can be read from the file. If no elements have been written and the file mode is Out_File, +then the closed file is empty. If no elements have been written and the file mode is Append_File, +then the closed file is unchanged. + +A.8.1 The Generic Package Sequential_IO + +13 December 2012 426 + + Ada Reference Manual — 2012 Edition + +The exception Status_Error is propagated if the given file is not open. + +procedure Delete(File : in out File_Type); + +Deletes the external file associated with the given file. The given file is closed, and the external +file ceases to exist. + +The exception Status_Error is propagated if the given file is not open. The exception Use_Error +is propagated if deletion of the external file is not supported by the external environment. + +procedure Reset(File : in out File_Type; Mode : in File_Mode); +procedure Reset(File : in out File_Type); + +Resets the given file so that reading from its elements can be restarted from the beginning of the +external file (for modes In_File and Inout_File), and so that writing to its elements can be +restarted at the beginning of the external file (for modes Out_File and Inout_File) or after the +last element of the external file (for mode Append_File). In particular, for direct access this +means that the current index is set to one. If a Mode parameter is supplied, the current mode of +the given file is set to the given mode. In addition, for sequential files, if the given file has mode +Out_File or Append_File when Reset is called, the last element written since the most recent +open or reset is the last element that can be read from the external file. If no elements have been +written and the file mode is Out_File, the reset file is empty. If no elements have been written +and the file mode is Append_File, then the reset file is unchanged. + +The exception Status_Error is propagated if the file is not open. The exception Use_Error is +propagated if the external environment does not support resetting for the external file and, also, +if the external environment does not support resetting to the specified mode for the external file. + +function Mode(File : in File_Type) return File_Mode; + +Returns the current mode of the given file. + +The exception Status_Error is propagated if the file is not open. + +function Name(File : in File_Type) return String; + +11 + +12 + +13 + +14 + +15 + +16/2 + +17 + +18 + +19 + +20 + +21 + +Returns a string which uniquely identifies the external file currently associated with the given +file (and may thus be used in an Open operation). + +22/2 + +The exception Status_Error is propagated if the given file is not open. The exception Use_Error +is propagated if the associated external file is a temporary file that cannot be opened by any +name. + +function Form(File : in File_Type) return String; + +Returns the form string for the external file currently associated with the given file. If an +external environment allows alternative specifications of the form (for example, abbreviations +using default options), the string returned by the function should correspond to a full +specification (that is, it should indicate explicitly all options selected, including default options). + +The exception Status_Error is propagated if the given file is not open. + +function Is_Open(File : in File_Type) return Boolean; + +Returns True if the file is open (that is, if it is associated with an external file); otherwise, returns +False. + +23 + +24 + +25 + +26 + +27 + +28/3 + +427 13 December 2012 + +File Management A.8.2 + + Ada Reference Manual — 2012 Edition + +29 + +An implementation may propagate Name_Error or Use_Error if an attempt is made to use an I/O feature +that cannot be supported by the implementation due to limitations in the external environment. Any such +restriction should be documented. + +Implementation Permissions + +A.8.3 Sequential Input-Output Operations + +Static Semantics + +The operations available for sequential input and output are described in this subclause. The exception +Status_Error is propagated if any of these operations is attempted for a file that is not open. + +procedure Read(File : in File_Type; Item : out Element_Type); + +Operates on a file of mode In_File. Reads an element from the given file, and returns the value +of this element in the Item parameter. + +The exception Mode_Error is propagated if the mode is not In_File. The exception End_Error is +propagated if no more elements can be read from the given file. The exception Data_Error can +be propagated if the element read cannot be interpreted as a value of the subtype Element_Type +(see A.13, “Exceptions in Input-Output”). + +procedure Write(File : in File_Type; Item : in Element_Type); + +Operates on a file of mode Out_File or Append_File. Writes the value of Item to the given file. + +The exception Mode_Error is propagated if the mode is not Out_File or Append_File. The +exception Use_Error is propagated if the capacity of the external file is exceeded. + +function End_Of_File(File : in File_Type) return Boolean; + +Operates on a file of mode In_File. Returns True if no more elements can be read from the given +file; otherwise, returns False. + +The exception Mode_Error is propagated if the mode is not In_File. + +A.8.4 The Generic Package Direct_IO + +The generic library package Direct_IO has the following declaration: + +Static Semantics + +with Ada.IO_Exceptions; +generic + type Element_Type is private; +package Ada.Direct_IO is + type File_Type is limited private; + type File_Mode is (In_File, Inout_File, Out_File); + type Count is range 0 .. implementation-defined; + subtype Positive_Count is Count range 1 .. Count'Last; + -- File management + procedure Create(File : in out File_Type; + Mode : in File_Mode := Inout_File; + Name : in String := ""; + Form : in String := ""); + +1 + +2 + +3 + +4 + +5 + +6 + +7 + +8 + +9/3 + +10 + +1 + +2 + +3 + +4 + +5 + +6 + +A.8.2 File Management + +13 December 2012 428 + + Ada Reference Manual — 2012 Edition + + procedure Open (File : in out File_Type; + Mode : in File_Mode; + Name : in String; + Form : in String := ""); + procedure Close (File : in out File_Type); + procedure Delete(File : in out File_Type); + procedure Reset (File : in out File_Type; Mode : in File_Mode); + procedure Reset (File : in out File_Type); + function Mode (File : in File_Type) return File_Mode; + function Name (File : in File_Type) return String; + function Form (File : in File_Type) return String; + function Is_Open(File : in File_Type) return Boolean; + -- Input and output operations + procedure Read (File : in File_Type; Item : out Element_Type; + From : in Positive_Count); + procedure Read (File : in File_Type; Item : out Element_Type); + procedure Write(File : in File_Type; Item : in Element_Type; + To : in Positive_Count); + procedure Write(File : in File_Type; Item : in Element_Type); + procedure Set_Index(File : in File_Type; To : in Positive_Count); + function Index(File : in File_Type) return Positive_Count; + function Size (File : in File_Type) return Count; + function End_Of_File(File : in File_Type) return Boolean; + -- Exceptions + Status_Error : exception renames IO_Exceptions.Status_Error; + Mode_Error : exception renames IO_Exceptions.Mode_Error; + Name_Error : exception renames IO_Exceptions.Name_Error; + Use_Error : exception renames IO_Exceptions.Use_Error; + Device_Error : exception renames IO_Exceptions.Device_Error; + End_Error : exception renames IO_Exceptions.End_Error; + Data_Error : exception renames IO_Exceptions.Data_Error; +private + ... -- not specified by the language +end Ada.Direct_IO; + +The type File_Type needs finalization (see 7.6) in every instantiation of Direct_IO. + +A.8.5 Direct Input-Output Operations + +Static Semantics + +The operations available for direct input and output are described in this subclause. The exception +Status_Error is propagated if any of these operations is attempted for a file that is not open. + +procedure Read(File : in File_Type; Item : out Element_Type; + From : in Positive_Count); +procedure Read(File : in File_Type; Item : out Element_Type); + +Operates on a file of mode In_File or Inout_File. In the case of the first form, sets the current +index of the given file to the index value given by the parameter From. Then (for both forms) +returns, in the parameter Item, the value of the element whose position in the given file is +specified by the current index of the file; finally, increases the current index by one. + +The exception Mode_Error is propagated if the mode of the given file is Out_File. The exception +End_Error is propagated if the index to be used exceeds the size of the external file. The +exception Data_Error can be propagated if the element read cannot be interpreted as a value of +the subtype Element_Type (see A.13). + +429 13 December 2012 + +The Generic Package Direct_IO A.8.4 + +7 + +8 + +9 + +10 + +11 + +12 + +13 + +14 + +15 + +16 + +17 + +18 + +19 + +20/2 + +1 + +2 + +3 + +4 + + Ada Reference Manual — 2012 Edition + +5 + +6 + +7 + +8 + +9 + +10 + +11 + +12 + +13 + +14 + +15/3 + +16 + +17 + +1 + +2 + +3 + +4 + +5 + +6 + +7 + +procedure Write(File : in File_Type; Item : in Element_Type; + To : in Positive_Count); +procedure Write(File : in File_Type; Item : in Element_Type); + +Operates on a file of mode Inout_File or Out_File. In the case of the first form, sets the index of +the given file to the index value given by the parameter To. Then (for both forms) gives the +value of the parameter Item to the element whose position in the given file is specified by the +current index of the file; finally, increases the current index by one. + +The exception Mode_Error is propagated if the mode of the given file is In_File. The exception +Use_Error is propagated if the capacity of the external file is exceeded. + +procedure Set_Index(File : in File_Type; To : in Positive_Count); + +Operates on a file of any mode. Sets the current index of the given file to the given index value +(which may exceed the current size of the file). + +function Index(File : in File_Type) return Positive_Count; + +Operates on a file of any mode. Returns the current index of the given file. + +function Size(File : in File_Type) return Count; + +Operates on a file of any mode. Returns the current size of the external file that is associated +with the given file. + +function End_Of_File(File : in File_Type) return Boolean; + +Operates on a file of mode In_File or Inout_File. Returns True if the current index exceeds the +size of the external file; otherwise, returns False. + +The exception Mode_Error is propagated if the mode of the given file is Out_File. + +NOTES +25 Append_File mode is not supported for the generic package Direct_IO. + +A.9 The Generic Package Storage_IO + +The generic package Storage_IO provides for reading from and writing to an in-memory buffer. This +generic package supports the construction of user-defined input-output packages. + +The generic library package Storage_IO has the following declaration: + +Static Semantics + +with Ada.IO_Exceptions; +with System.Storage_Elements; +generic + type Element_Type is private; +package Ada.Storage_IO is + pragma Preelaborate(Storage_IO); + Buffer_Size : constant System.Storage_Elements.Storage_Count := + implementation-defined; + subtype Buffer_Type is + System.Storage_Elements.Storage_Array(1..Buffer_Size); + -- Input and output operations + procedure Read (Buffer : in Buffer_Type; Item : out Element_Type); + procedure Write(Buffer : out Buffer_Type; Item : in Element_Type); + +A.8.5 Direct Input-Output Operations + +13 December 2012 430 + + Ada Reference Manual — 2012 Edition + + -- Exceptions + Data_Error : exception renames IO_Exceptions.Data_Error; +end Ada.Storage_IO; + +In each instance, the constant Buffer_Size has a value that is the size (in storage elements) of the buffer +required to represent the content of an object of subtype Element_Type, including any implicit levels of +indirection used by the implementation. The Read and Write procedures of Storage_IO correspond to the +Read and Write procedures of Direct_IO (see A.8.4), but with the content of the Item parameter being read +from or written into the specified Buffer, rather than an external file. + +8 + +9 + +10 + +NOTES +26 A buffer used for Storage_IO holds only one element at a time; an external file used for Direct_IO holds a sequence of +elements. + +11 + +A.10 Text Input-Output + +Static Semantics + +This subclause describes the package Text_IO, which provides facilities for input and output in human- +readable form. Each file is read or written sequentially, as a sequence of characters grouped into lines, and +as a sequence of lines grouped into pages. The specification of the package is given below in subclause +A.10.1. + +The facilities for file management given above, in subclauses A.8.2 and A.8.3, are available for text input- +output. In place of Read and Write, however, there are procedures Get and Put that input values of suitable +types from text files, and output values to them. These values are provided to the Put procedures, and +returned by the Get procedures, in a parameter Item. Several overloaded procedures of these names exist, +for different types of Item. These Get procedures analyze the input sequences of characters based on +lexical elements (see Clause 2) and return the corresponding values; the Put procedures output the given +values as appropriate lexical elements. Procedures Get and Put are also available that input and output +individual characters treated as character values rather than as lexical elements. Related to character input +are procedures to look ahead at the next character without reading it, and to read a character +“immediately” without waiting for an end-of-line to signal availability. + +In addition to the procedures Get and Put for numeric and enumeration types of Item that operate on text +files, analogous procedures are provided that read from and write to a parameter of type String. These +procedures perform the same analysis and composition of character sequences as their counterparts which +have a file parameter. + +For all Get and Put procedures that operate on text files, and for many other subprograms, there are forms +with and without a file parameter. Each such Get procedure operates on an input file, and each such Put +procedure operates on an output file. If no file is specified, a default input file or a default output file is +used. + +At the beginning of program execution the default input and output files are the so-called standard input +file and standard output file. These files are open, have respectively the current modes In_File and +Out_File, and are associated with two implementation-defined external files. Procedures are provided to +change the current default input file and the current default output file. + +At the beginning of program execution a default file for program-dependent error-related text output is the +so-called standard error file. This file is open, has the current mode Out_File, and is associated with an +implementation-defined external file. A procedure is provided to change the current default error file. + +1/3 + +2/3 + +3 + +4 + +5 + +6 + +431 13 December 2012 + +The Generic Package Storage_IO A.9 + + Ada Reference Manual — 2012 Edition + +From a logical point of view, a text file is a sequence of pages, a page is a sequence of lines, and a line is a +sequence of characters; the end of a line is marked by a line terminator; the end of a page is marked by the +combination of a line terminator immediately followed by a page terminator; and the end of a file is +marked by the combination of a line terminator immediately followed by a page terminator and then a file +terminator. Terminators are generated during output; either by calls of procedures provided expressly for +that purpose; or implicitly as part of other operations, for example, when a bounded line length, a bounded +page length, or both, have been specified for a file. + +The actual nature of terminators is not defined by the language and hence depends on the implementation. +Although terminators are recognized or generated by certain of the procedures that follow, they are not +necessarily implemented as characters or as sequences of characters. Whether they are characters (and if +so which ones) in any particular implementation need not concern a user who neither explicitly outputs nor +explicitly inputs control characters. The effect of input (Get) or output (Put) of control characters (other +than horizontal tabulation) is not specified by the language. + +The characters of a line are numbered, starting from one; the number of a character is called its column +number. For a line terminator, a column number is also defined: it is one more than the number of +characters in the line. The lines of a page, and the pages of a file, are similarly numbered. The current +column number is the column number of the next character or line terminator to be transferred. The +current line number is the number of the current line. The current page number is the number of the +current page. These numbers are values of the subtype Positive_Count of the type Count (by convention, +the value zero of the type Count is used to indicate special conditions). + +type Count is range 0 .. implementation-defined; +subtype Positive_Count is Count range 1 .. Count'Last; + +For an output file or an append file, a maximum line length can be specified and a maximum page length +can be specified. If a value to be output cannot fit on the current line, for a specified maximum line length, +then a new line is automatically started before the value is output; if, further, this new line cannot fit on the +current page, for a specified maximum page length, then a new page is automatically started before the +value is output. Functions are provided to determine the maximum line length and the maximum page +length. When a file is opened with mode Out_File or Append_File, both values are zero: by convention, +this means that the line lengths and page lengths are unbounded. (Consequently, output consists of a single +line if the subprograms for explicit control of line and page structure are not used.) The constant +Unbounded is provided for this purpose. + +A.10.1 The Package Text_IO + +The library package Text_IO has the following declaration: + +Static Semantics + +with Ada.IO_Exceptions; +package Ada.Text_IO is + type File_Type is limited private; + type File_Mode is (In_File, Out_File, Append_File); + type Count is range 0 .. implementation-defined; + subtype Positive_Count is Count range 1 .. Count'Last; + Unbounded : constant Count := 0; -- line and page length + subtype Field is Integer range 0 .. implementation-defined; + subtype Number_Base is Integer range 2 .. 16; + type Type_Set is (Lower_Case, Upper_Case); + -- File Management + +7 + +8 + +9 + +10 + +11 + +1 + +2 + +3 + +4 + +5 + +6 + +7 + +8 + +A.10 Text Input-Output + +13 December 2012 432 + + Ada Reference Manual — 2012 Edition + + procedure Create (File : in out File_Type; + Mode : in File_Mode := Out_File; + Name : in String := ""; + Form : in String := ""); + procedure Open (File : in out File_Type; + Mode : in File_Mode; + Name : in String; + Form : in String := ""); + procedure Close (File : in out File_Type); + procedure Delete (File : in out File_Type); + procedure Reset (File : in out File_Type; Mode : in File_Mode); + procedure Reset (File : in out File_Type); + function Mode (File : in File_Type) return File_Mode; + function Name (File : in File_Type) return String; + function Form (File : in File_Type) return String; + function Is_Open(File : in File_Type) return Boolean; + -- Control of default input and output files + procedure Set_Input (File : in File_Type); + procedure Set_Output(File : in File_Type); + procedure Set_Error (File : in File_Type); + function Standard_Input return File_Type; + function Standard_Output return File_Type; + function Standard_Error return File_Type; + function Current_Input return File_Type; + function Current_Output return File_Type; + function Current_Error return File_Type; + type File_Access is access constant File_Type; + function Standard_Input return File_Access; + function Standard_Output return File_Access; + function Standard_Error return File_Access; + function Current_Input return File_Access; + function Current_Output return File_Access; + function Current_Error return File_Access; +--Buffer control + procedure Flush (File : in File_Type); + procedure Flush; + -- Specification of line and page lengths + procedure Set_Line_Length(File : in File_Type; To : in Count); + procedure Set_Line_Length(To : in Count); + procedure Set_Page_Length(File : in File_Type; To : in Count); + procedure Set_Page_Length(To : in Count); + function Line_Length(File : in File_Type) return Count; + function Line_Length return Count; + function Page_Length(File : in File_Type) return Count; + function Page_Length return Count; + -- Column, Line, and Page Control + procedure New_Line (File : in File_Type; + Spacing : in Positive_Count := 1); + procedure New_Line (Spacing : in Positive_Count := 1); + procedure Skip_Line (File : in File_Type; + Spacing : in Positive_Count := 1); + procedure Skip_Line (Spacing : in Positive_Count := 1); + function End_Of_Line(File : in File_Type) return Boolean; + function End_Of_Line return Boolean; + procedure New_Page (File : in File_Type); + procedure New_Page; + +9 + +10 + +11 + +12 + +13 + +14 + +15 + +16 + +17 + +18 + +19 + +20 + +21/1 + +22 + +23 + +24 + +25 + +26 + +27 + +28 + +29 + +30 + +31 + +433 13 December 2012 + +The Package Text_IO A.10.1 + + Ada Reference Manual — 2012 Edition + +32 + +33 + +34 + +35 + +36 + +37 + +38 + +39 + +40 + +41 + +42 + +43 + +44 + +45 + +46 + +47 + +48 + +49 + +49.1/2 + +50 + +51 + +52 + +53 + + procedure Skip_Page (File : in File_Type); + procedure Skip_Page; + function End_Of_Page(File : in File_Type) return Boolean; + function End_Of_Page return Boolean; + function End_Of_File(File : in File_Type) return Boolean; + function End_Of_File return Boolean; + procedure Set_Col (File : in File_Type; To : in Positive_Count); + procedure Set_Col (To : in Positive_Count); + procedure Set_Line(File : in File_Type; To : in Positive_Count); + procedure Set_Line(To : in Positive_Count); + function Col (File : in File_Type) return Positive_Count; + function Col return Positive_Count; + function Line(File : in File_Type) return Positive_Count; + function Line return Positive_Count; + function Page(File : in File_Type) return Positive_Count; + function Page return Positive_Count; + -- Character Input-Output + procedure Get(File : in File_Type; Item : out Character); + procedure Get(Item : out Character); + procedure Put(File : in File_Type; Item : in Character); + procedure Put(Item : in Character); + procedure Look_Ahead (File : in File_Type; + Item : out Character; + End_Of_Line : out Boolean); + procedure Look_Ahead (Item : out Character; + End_Of_Line : out Boolean); + procedure Get_Immediate(File : in File_Type; + Item : out Character); + procedure Get_Immediate(Item : out Character); + procedure Get_Immediate(File : in File_Type; + Item : out Character; + Available : out Boolean); + procedure Get_Immediate(Item : out Character; + Available : out Boolean); + -- String Input-Output + procedure Get(File : in File_Type; Item : out String); + procedure Get(Item : out String); + procedure Put(File : in File_Type; Item : in String); + procedure Put(Item : in String); + procedure Get_Line(File : in File_Type; + Item : out String; + Last : out Natural); + procedure Get_Line(Item : out String; Last : out Natural); + function Get_Line(File : in File_Type) return String; + function Get_Line return String; + procedure Put_Line(File : in File_Type; Item : in String); + procedure Put_Line(Item : in String); +-- Generic packages for Input-Output of Integer Types + generic + type Num is range <>; + package Integer_IO is + Default_Width : Field := Num'Width; + Default_Base : Number_Base := 10; + +A.10.1 The Package Text_IO + +13 December 2012 434 + + Ada Reference Manual — 2012 Edition + + procedure Get(File : in File_Type; + Item : out Num; + Width : in Field := 0); + procedure Get(Item : out Num; + Width : in Field := 0); + procedure Put(File : in File_Type; + Item : in Num; + Width : in Field := Default_Width; + Base : in Number_Base := Default_Base); + procedure Put(Item : in Num; + Width : in Field := Default_Width; + Base : in Number_Base := Default_Base); + procedure Get(From : in String; + Item : out Num; + Last : out Positive); + procedure Put(To : out String; + Item : in Num; + Base : in Number_Base := Default_Base); + end Integer_IO; + generic + type Num is mod <>; + package Modular_IO is + Default_Width : Field := Num'Width; + Default_Base : Number_Base := 10; + procedure Get(File : in File_Type; + Item : out Num; + Width : in Field := 0); + procedure Get(Item : out Num; + Width : in Field := 0); + procedure Put(File : in File_Type; + Item : in Num; + Width : in Field := Default_Width; + Base : in Number_Base := Default_Base); + procedure Put(Item : in Num; + Width : in Field := Default_Width; + Base : in Number_Base := Default_Base); + procedure Get(From : in String; + Item : out Num; + Last : out Positive); + procedure Put(To : out String; + Item : in Num; + Base : in Number_Base := Default_Base); + end Modular_IO; + -- Generic packages for Input-Output of Real Types + generic + type Num is digits <>; + package Float_IO is + Default_Fore : Field := 2; + Default_Aft : Field := Num'Digits-1; + Default_Exp : Field := 3; + procedure Get(File : in File_Type; + Item : out Num; + Width : in Field := 0); + procedure Get(Item : out Num; + Width : in Field := 0); + +54 + +55 + +56 + +57 + +58 + +59 + +60 + +61 + +62 + +63 + +64 + +65 + +435 13 December 2012 + +The Package Text_IO A.10.1 + + 66 + +67 + +68 + +69 + +70 + +71 + +72 + +73 + +74 + +75 + +Ada Reference Manual — 2012 Edition + + procedure Put(File : in File_Type; + Item : in Num; + Fore : in Field := Default_Fore; + Aft : in Field := Default_Aft; + Exp : in Field := Default_Exp); + procedure Put(Item : in Num; + Fore : in Field := Default_Fore; + Aft : in Field := Default_Aft; + Exp : in Field := Default_Exp); + procedure Get(From : in String; + Item : out Num; + Last : out Positive); + procedure Put(To : out String; + Item : in Num; + Aft : in Field := Default_Aft; + Exp : in Field := Default_Exp); + end Float_IO; + generic + type Num is delta <>; + package Fixed_IO is + Default_Fore : Field := Num'Fore; + Default_Aft : Field := Num'Aft; + Default_Exp : Field := 0; + procedure Get(File : in File_Type; + Item : out Num; + Width : in Field := 0); + procedure Get(Item : out Num; + Width : in Field := 0); + procedure Put(File : in File_Type; + Item : in Num; + Fore : in Field := Default_Fore; + Aft : in Field := Default_Aft; + Exp : in Field := Default_Exp); + procedure Put(Item : in Num; + Fore : in Field := Default_Fore; + Aft : in Field := Default_Aft; + Exp : in Field := Default_Exp); + procedure Get(From : in String; + Item : out Num; + Last : out Positive); + procedure Put(To : out String; + Item : in Num; + Aft : in Field := Default_Aft; + Exp : in Field := Default_Exp); + end Fixed_IO; + generic + type Num is delta <> digits <>; + package Decimal_IO is + Default_Fore : Field := Num'Fore; + Default_Aft : Field := Num'Aft; + Default_Exp : Field := 0; + procedure Get(File : in File_Type; + Item : out Num; + Width : in Field := 0); + procedure Get(Item : out Num; + Width : in Field := 0); + +A.10.1 The Package Text_IO + +13 December 2012 436 + + Ada Reference Manual — 2012 Edition + + procedure Put(File : in File_Type; + Item : in Num; + Fore : in Field := Default_Fore; + Aft : in Field := Default_Aft; + Exp : in Field := Default_Exp); + procedure Put(Item : in Num; + Fore : in Field := Default_Fore; + Aft : in Field := Default_Aft; + Exp : in Field := Default_Exp); + procedure Get(From : in String; + Item : out Num; + Last : out Positive); + procedure Put(To : out String; + Item : in Num; + Aft : in Field := Default_Aft; + Exp : in Field := Default_Exp); + end Decimal_IO; + -- Generic package for Input-Output of Enumeration Types + generic + type Enum is (<>); + package Enumeration_IO is + Default_Width : Field := 0; + Default_Setting : Type_Set := Upper_Case; + procedure Get(File : in File_Type; + Item : out Enum); + procedure Get(Item : out Enum); + procedure Put(File : in File_Type; + Item : in Enum; + Width : in Field := Default_Width; + Set : in Type_Set := Default_Setting); + procedure Put(Item : in Enum; + Width : in Field := Default_Width; + Set : in Type_Set := Default_Setting); + procedure Get(From : in String; + Item : out Enum; + Last : out Positive); + procedure Put(To : out String; + Item : in Enum; + Set : in Type_Set := Default_Setting); + end Enumeration_IO; +-- Exceptions + Status_Error : exception renames IO_Exceptions.Status_Error; + Mode_Error : exception renames IO_Exceptions.Mode_Error; + Name_Error : exception renames IO_Exceptions.Name_Error; + Use_Error : exception renames IO_Exceptions.Use_Error; + Device_Error : exception renames IO_Exceptions.Device_Error; + End_Error : exception renames IO_Exceptions.End_Error; + Data_Error : exception renames IO_Exceptions.Data_Error; + Layout_Error : exception renames IO_Exceptions.Layout_Error; +private + ... -- not specified by the language +end Ada.Text_IO; + +76 + +77 + +78 + +79 + +80 + +81 + +82 + +83 + +84 + +85 + +The type File_Type needs finalization (see 7.6). + +86/2 + +A.10.2 Text File Management + +Static Semantics + +The only allowed file modes for text files are the modes In_File, Out_File, and Append_File. The +subprograms given in subclause A.8.2 for the control of external files, and the function End_Of_File given + +1 + +437 13 December 2012 + +The Package Text_IO A.10.1 + + Ada Reference Manual — 2012 Edition + +in subclause A.8.3 for sequential input-output, are also available for text files. There is also a version of +End_Of_File that refers to the current default input file. For text files, the procedures have the following +additional effects: + +• For the procedures Create and Open: After a file with mode Out_File or Append_File is opened, +the page length and line length are unbounded (both have the conventional value zero). After a +file (of any mode) is opened, the current column, current line, and current page numbers are set +to one. If the mode is Append_File, it is implementation defined whether a page terminator will +separate preexisting text in the file from the new text to be written. + +• For the procedure Close: If the file has the current mode Out_File or Append_File, has the effect +of calling New_Page, unless the current page is already terminated; then outputs a file +terminator. + +• For the procedure Reset: If the file has the current mode Out_File or Append_File, has the effect +of calling New_Page, unless the current page is already terminated; then outputs a file +terminator. The current column, line, and page numbers are set to one, and the line and page +lengths to Unbounded. If the new mode is Append_File, it is implementation defined whether a +page terminator will separate preexisting text in the file from the new text to be written. + +The exception Mode_Error is propagated by the procedure Reset upon an attempt to change the mode of a +file that is the current default input file, the current default output file, or the current default error file. + +NOTES +27 An implementation can define the Form parameter of Create and Open to control effects including the following: + +• +• + +the interpretation of line and column numbers for an interactive file, and + +the interpretation of text formats in a file created by a foreign program. + +A.10.3 Default Input, Output, and Error Files + +Static Semantics + +The following subprograms provide for the control of the particular default files that are used when a file +parameter is omitted from a Get, Put, or other operation of text input-output described below, or when +application-dependent error-related text is to be output. + +procedure Set_Input(File : in File_Type); + +Operates on a file of mode In_File. Sets the current default input file to File. + +The exception Status_Error is propagated if the given file is not open. The exception +Mode_Error is propagated if the mode of the given file is not In_File. + +procedure Set_Output(File : in File_Type); +procedure Set_Error (File : in File_Type); + +Each operates on a file of mode Out_File or Append_File. Set_Output sets the current default +output file to File. Set_Error sets the current default error file to File. The exception Status_Error +is propagated if the given file is not open. The exception Mode_Error is propagated if the mode +of the given file is not Out_File or Append_File. + +function Standard_Input return File_Type; +function Standard_Input return File_Access; + +Returns the standard input file (see A.10), or an access value designating the standard input file, +respectively. + +2 + +3 + +4 + +5 + +6 + +7 + +8 + +1 + +2 + +3 + +4 + +5 + +6 + +7 + +8 + +A.10.2 Text File Management + +13 December 2012 438 + + Ada Reference Manual — 2012 Edition + +function Standard_Output return File_Type; +function Standard_Output return File_Access; + +Returns the standard output file (see A.10) or an access value designating the standard output +file, respectively. + +function Standard_Error return File_Type; +function Standard_Error return File_Access; + +9 + +10 + +11 + +Returns the standard error file (see A.10), or an access value designating the standard error file, +respectively. + +12/1 + +The Form strings implicitly associated with the opening of Standard_Input, Standard_Output, and +Standard_Error at the start of program execution are implementation defined. + +function Current_Input return File_Type; +function Current_Input return File_Access; + +Returns the current default input file, or an access value designating the current default input +file, respectively. + +function Current_Output return File_Type; +function Current_Output return File_Access; + +Returns the current default output file, or an access value designating the current default output +file, respectively. + +function Current_Error return File_Type; +function Current_Error return File_Access; + +Returns the current default error file, or an access value designating the current default error file, +respectively. + +procedure Flush (File : in File_Type); +procedure Flush; + +The effect of Flush is the same as the corresponding subprogram in Streams.Stream_IO (see +A.12.1). If File is not explicitly specified, Current_Output is used. + +The execution of a program is erroneous if it invokes an operation on a current default input, default +output, or default error file, and if the corresponding file object is closed or no longer exists. + +Erroneous Execution + +This paragraph was deleted. + +NOTES +28 The standard input, standard output, and standard error files cannot be opened, closed, reset, or deleted, because the +parameter File of the corresponding procedures has the mode in out. + +29 The standard input, standard output, and standard error files are different file objects, but not necessarily different +external files. + +13 + +14 + +15 + +16 + +17 + +18 + +19 + +20/1 + +21 + +22/1 + +23/1 + +24 + +25 + +A.10.4 Specification of Line and Page Lengths + +Static Semantics + +The subprograms described in this subclause are concerned with the line and page structure of a file of +mode Out_File or Append_File. They operate either on the file given as the first parameter, or, in the +absence of such a file parameter, on the current default output file. They provide for output of text with a +specified maximum line length or page length. In these cases, line and page terminators are output + +1 + +439 13 December 2012 + +Default Input, Output, and Error Files A.10.3 + + Ada Reference Manual — 2012 Edition + +implicitly and automatically when needed. When line and page lengths are unbounded (that is, when they +have the conventional value zero), as in the case of a newly opened file, new lines and new pages are only +started when explicitly called for. + +In all cases, the exception Status_Error is propagated if the file to be used is not open; the exception +Mode_Error is propagated if the mode of the file is not Out_File or Append_File. + +procedure Set_Line_Length(File : in File_Type; To : in Count); +procedure Set_Line_Length(To : in Count); + +Sets the maximum line length of the specified output or append file to the number of characters +specified by To. The value zero for To specifies an unbounded line length. + +The exception Use_Error is propagated if the specified line length is inappropriate for the +associated external file. + +procedure Set_Page_Length(File : in File_Type; To : in Count); +procedure Set_Page_Length(To : in Count); + +Sets the maximum page length of the specified output or append file to the number of lines +specified by To. The value zero for To specifies an unbounded page length. + +The exception Use_Error is propagated if the specified page length is inappropriate for the +associated external file. + +function Line_Length(File : in File_Type) return Count; +function Line_Length return Count; + +Returns the maximum line length currently set for the specified output or append file, or zero if +the line length is unbounded. + +function Page_Length(File : in File_Type) return Count; +function Page_Length return Count; + +Returns the maximum page length currently set for the specified output or append file, or zero if +the page length is unbounded. + +A.10.5 Operations on Columns, Lines, and Pages + +Static Semantics + +The subprograms described in this subclause provide for explicit control of line and page structure; they +operate either on the file given as the first parameter, or, in the absence of such a file parameter, on the +appropriate (input or output) current default file. The exception Status_Error is propagated by any of these +subprograms if the file to be used is not open. + +procedure New_Line(File : in File_Type; Spacing : in Positive_Count := 1); +procedure New_Line(Spacing : in Positive_Count := 1); + +Operates on a file of mode Out_File or Append_File. + +For a Spacing of one: Outputs a line terminator and sets the current column number to one. Then +increments the current line number by one, except in the case that the current line number is +already greater than or equal to the maximum page length, for a bounded page length; in that +case a page terminator is output, the current page number is incremented by one, and the current +line number is set to one. + +For a Spacing greater than one, the above actions are performed Spacing times. + +2 + +3 + +4 + +5 + +6 + +7 + +8 + +9 + +10 + +11 + +12 + +1 + +2 + +3 + +4 + +5 + +A.10.4 Specification of Line and Page Lengths + +13 December 2012 440 + + Ada Reference Manual — 2012 Edition + +The exception Mode_Error is propagated if the mode is not Out_File or Append_File. + +procedure Skip_Line(File : in File_Type; Spacing : in Positive_Count := 1); +procedure Skip_Line(Spacing : in Positive_Count := 1); + +Operates on a file of mode In_File. + +For a Spacing of one: Reads and discards all characters until a line terminator has been read, and +then sets the current column number to one. If the line terminator is not immediately followed by +a page terminator, the current line number is incremented by one. Otherwise, if the line +terminator is immediately followed by a page terminator, then the page terminator is skipped, +the current page number is incremented by one, and the current line number is set to one. + +For a Spacing greater than one, the above actions are performed Spacing times. + +The exception Mode_Error is propagated if the mode is not In_File. The exception End_Error is +propagated if an attempt is made to read a file terminator. + +function End_Of_Line(File : in File_Type) return Boolean; +function End_Of_Line return Boolean; + +6 + +7 + +8 + +9 + +10 + +11 + +12 + +Operates on a file of mode In_File. Returns True if a line terminator or a file terminator is next; +otherwise, returns False. + +13/3 + +The exception Mode_Error is propagated if the mode is not In_File. + +procedure New_Page(File : in File_Type); +procedure New_Page; + +Operates on a file of mode Out_File or Append_File. Outputs a line terminator if the current line +is not terminated, or if the current page is empty (that is, if the current column and line numbers +are both equal to one). Then outputs a page terminator, which terminates the current page. Adds +one to the current page number and sets the current column and line numbers to one. + +The exception Mode_Error is propagated if the mode is not Out_File or Append_File. + +procedure Skip_Page(File : in File_Type); +procedure Skip_Page; + +Operates on a file of mode In_File. Reads and discards all characters and line terminators until a +page terminator has been read. Then adds one to the current page number, and sets the current +column and line numbers to one. + +The exception Mode_Error is propagated if the mode is not In_File. The exception End_Error is +propagated if an attempt is made to read a file terminator. + +function End_Of_Page(File : in File_Type) return Boolean; +function End_Of_Page return Boolean; + +Operates on a file of mode In_File. Returns True if the combination of a line terminator and a +page terminator is next, or if a file terminator is next; otherwise, returns False. + +The exception Mode_Error is propagated if the mode is not In_File. + +function End_Of_File(File : in File_Type) return Boolean; +function End_Of_File return Boolean; + +Operates on a file of mode In_File. Returns True if a file terminator is next, or if the +combination of a line, a page, and a file terminator is next; otherwise, returns False. + +14 + +15 + +16 + +17 + +18 + +19 + +20 + +21 + +22/3 + +23 + +24 + +25/3 + +441 13 December 2012 + +Operations on Columns, Lines, and Pages A.10.5 + + Ada Reference Manual — 2012 Edition + +The exception Mode_Error is propagated if the mode is not In_File. + +The following subprograms provide for the control of the current position of reading or writing in a file. In +all cases, the default file is the current output file. + +procedure Set_Col(File : in File_Type; To : in Positive_Count); +procedure Set_Col(To : in Positive_Count); + +If the file mode is Out_File or Append_File: + +• If the value specified by To is greater than the current column number, outputs spaces, +adding one to the current column number after each space, until the current column +number equals the specified value. If the value specified by To is equal to the current +column number, there is no effect. If the value specified by To is less than the current +column number, has the effect of calling New_Line (with a spacing of one), then +outputs (To – 1) spaces, and sets the current column number to the specified value. +• The exception Layout_Error is propagated if the value specified by To exceeds +Line_Length when the line length is bounded (that is, when it does not have the +conventional value zero). + +If the file mode is In_File: + +• Reads (and discards) individual characters, line terminators, and page terminators, +until the next character to be read has a column number that equals the value specified +by To; there is no effect if the current column number already equals this value. Each +transfer of a character or terminator maintains the current column, line, and page +numbers in the same way as a Get procedure (see A.10.6). (Short lines will be skipped +until a line is reached that has a character at the specified column position.) + +• The exception End_Error is propagated if an attempt is made to read a file terminator. + +procedure Set_Line(File : in File_Type; To : in Positive_Count); +procedure Set_Line(To : in Positive_Count); + +If the file mode is Out_File or Append_File: + +• If the value specified by To is greater than the current line number, has the effect of +repeatedly calling New_Line (with a spacing of one), until the current line number +equals the specified value. If the value specified by To is equal to the current line +number, there is no effect. If the value specified by To is less than the current line +number, has the effect of calling New_Page followed, if To is greater than 1, by a call +of New_Line with a spacing equal to (To – 1). + +• The exception Layout_Error is propagated if the value specified by To exceeds +Page_Length when the page length is bounded (that is, when it does not have the +conventional value zero). + +If the mode is In_File: + +• Has the effect of repeatedly calling Skip_Line (with a spacing of one), until the current +line number equals the value specified by To; there is no effect if the current line +number already equals this value. (Short pages will be skipped until a page is reached +that has a line at the specified line position.) + +• The exception End_Error is propagated if an attempt is made to read a file terminator. + +function Col(File : in File_Type) return Positive_Count; +function Col return Positive_Count; + +Returns the current column number. + +26 + +27 + +28 + +29 + +30 + +31 + +32 + +33 + +34 + +35 + +36 + +37/3 + +38 + +39 + +40 + +41 + +42 + +43 + +A.10.5 Operations on Columns, Lines, and Pages + +13 December 2012 442 + + Ada Reference Manual — 2012 Edition + +The exception Layout_Error is propagated if this number exceeds Count'Last. + +function Line(File : in File_Type) return Positive_Count; +function Line return Positive_Count; + +Returns the current line number. + +The exception Layout_Error is propagated if this number exceeds Count'Last. + +function Page(File : in File_Type) return Positive_Count; +function Page return Positive_Count; + +Returns the current page number. + +The exception Layout_Error is propagated if this number exceeds Count'Last. + +The column number, line number, or page number are allowed to exceed Count'Last (as a consequence of +the input or output of sufficiently many characters, lines, or pages). These events do not cause any +exception to be propagated. However, a call of Col, Line, or Page propagates the exception Layout_Error +if the corresponding number exceeds Count'Last. + +NOTES +30 A page terminator is always skipped whenever the preceding line terminator is skipped. An implementation may +represent the combination of these terminators by a single character, provided that it is properly recognized on input. + +A.10.6 Get and Put Procedures + +Static Semantics + +The procedures Get and Put for items of the type Character, String, numeric types, and enumeration types +are described in subsequent subclauses. Features of these procedures that are common to most of these +types are described in this subclause. The Get and Put procedures for items of type Character and String +deal with individual character values; the Get and Put procedures for numeric and enumeration types treat +the items as lexical elements. + +All procedures Get and Put have forms with a file parameter, written first. Where this parameter is +omitted, the appropriate (input or output) current default file is understood to be specified. Each procedure +Get operates on a file of mode In_File. Each procedure Put operates on a file of mode Out_File or +Append_File. + +All procedures Get and Put maintain the current column, line, and page numbers of the specified file: the +effect of each of these procedures upon these numbers is the result of the effects of individual transfers of +characters and of individual output or skipping of terminators. Each transfer of a character adds one to the +current column number. Each output of a line terminator sets the current column number to one and adds +one to the current line number. Each output of a page terminator sets the current column and line numbers +to one and adds one to the current page number. For input, each skipping of a line terminator sets the +current column number to one and adds one to the current line number; each skipping of a page terminator +sets the current column and line numbers to one and adds one to the current page number. Similar +considerations apply to the procedures Get_Line, Put_Line, and Set_Col. + +Several Get and Put procedures, for numeric and enumeration types, have format parameters which +specify field lengths; these parameters are of the nonnegative subtype Field of the type Integer. + +Input-output of enumeration values uses the syntax of the corresponding lexical elements. Any Get +procedure for an enumeration type begins by skipping any leading blanks, or line or page terminators. A +blank is defined as a space or a horizontal tabulation character. Next, characters are input only so long as + +443 13 December 2012 + +Operations on Columns, Lines, and Pages A.10.5 + +44 + +45 + +46 + +47 + +48 + +49 + +50 + +51 + +52 + +1 + +2 + +3 + +4 + +5/2 + + Ada Reference Manual — 2012 Edition + +the sequence input is an initial sequence of an identifier or of a character literal (in particular, input ceases +when a line terminator is encountered). The character or line terminator that causes input to cease remains +available for subsequent input. + +For a numeric type, the Get procedures have a format parameter called Width. If the value given for this +parameter is zero, the Get procedure proceeds in the same manner as for enumeration types, but using the +syntax of numeric literals instead of that of enumeration literals. If a nonzero value is given, then exactly +Width characters are input, or the characters up to a line terminator, whichever comes first; any skipped +leading blanks are included in the count. The syntax used for numeric literals is an extended syntax that +allows a leading sign (but no intervening blanks, or line or page terminators) and that also allows (for real +types) an integer literal as well as forms that have digits only before the point or only after the point. + +Any Put procedure, for an item of a numeric or an enumeration type, outputs the value of the item as a +numeric literal, identifier, or character literal, as appropriate. This is preceded by leading spaces if required +by the format parameters Width or Fore (as described in later subclauses), and then a minus sign for a +negative value; for an enumeration type, the spaces follow instead of leading. The format given for a Put +procedure is overridden if it is insufficiently wide, by using the minimum needed width. + +Two further cases arise for Put procedures for numeric and enumeration types, if the line length of the +specified output file is bounded (that is, if it does not have the conventional value zero). If the number of +characters to be output does not exceed the maximum line length, but is such that they cannot fit on the +current line, starting from the current column, then (in effect) New_Line is called (with a spacing of one) +before output of the item. Otherwise, if the number of characters exceeds the maximum line length, then +the exception Layout_Error is propagated and nothing is output. + +The exception Status_Error is propagated by any of the procedures Get, Get_Line, Put, and Put_Line if the +file to be used is not open. The exception Mode_Error is propagated by the procedures Get and Get_Line +if the mode of the file to be used is not In_File; and by the procedures Put and Put_Line, if the mode is not +Out_File or Append_File. + +The exception End_Error is propagated by a Get procedure if an attempt is made to skip a file terminator. +The exception Data_Error is propagated by a Get procedure if the sequence finally input is not a lexical +element corresponding to the type, in particular if no characters were input; for this test, leading blanks are +ignored; for an item of a numeric type, when a sign is input, this rule applies to the succeeding numeric +literal. The exception Layout_Error is propagated by a Put procedure that outputs to a parameter of type +String, if the length of the actual string is insufficient for the output of the item. + +In the examples, here and in subclauses A.10.8 and A.10.9, the string quotes and the lower case letter b are +not transferred: they are shown only to reveal the layout and spaces. + +Examples + +N : Integer; + ... +Get(N); + +-- Characters at input Sequence input + +Value of N + +-- bb–12535b +-- bb12_535e1b +-- bb12_535e; + +–12535 +12_535e1 +12_535e + +–12535 +125350 +(none) Data_Error raised + +Example of overridden width parameter: + +Put(Item => -23, Width => 2); -- "–23" + +6 + +7 + +8 + +9 + +10 + +11 + +12 + +13 + +14 + +15 + +A.10.6 Get and Put Procedures + +13 December 2012 444 + + + Ada Reference Manual — 2012 Edition + +A.10.7 Input-Output of Characters and Strings + +For an item of type Character the following procedures are provided: + +procedure Get(File : in File_Type; Item : out Character); +procedure Get(Item : out Character); + +Static Semantics + +After skipping any line terminators and any page terminators, reads the next character from the +specified input file and returns the value of this character in the out parameter Item. + +The exception End_Error is propagated if an attempt is made to skip a file terminator. + +procedure Put(File : in File_Type; Item : in Character); +procedure Put(Item : in Character); + +If the line length of the specified output file is bounded (that is, does not have the conventional +value zero), and the current column number exceeds it, has the effect of calling New_Line with a +spacing of one. Then, or otherwise, outputs the given character to the file. + +procedure Look_Ahead (File : in File_Type; + Item : out Character; + End_Of_Line : out Boolean); +procedure Look_Ahead (Item : out Character; + End_Of_Line : out Boolean); + +Status_Error is propagated if the file is not open. Mode_Error is propagated if the mode of the +file is not In_File. Sets End_Of_Line to True if at end of line, including if at end of page or at +end of file; in each of these cases the value of Item is not specified. Otherwise, End_Of_Line is +set to False and Item is set to the next character (without consuming it) from the file. + +procedure Get_Immediate(File : in File_Type; + Item : out Character); +procedure Get_Immediate(Item : out Character); + +Reads the next character, either control or graphic, from the specified File or the default input +file. Status_Error is propagated if the file is not open. Mode_Error is propagated if the mode of +the file is not In_File. End_Error is propagated if at the end of the file. The current column, line +and page numbers for the file are not affected. + +procedure Get_Immediate(File : in File_Type; + Item : out Character; + Available : out Boolean); +procedure Get_Immediate(Item : out Character; + Available : out Boolean); + +If a character, either control or graphic, is available from the specified File or the default input +file, then the character is read; Available is True and Item contains the value of this character. If +a character is not available, then Available is False and the value of Item is not specified. +Status_Error is propagated if the file is not open. Mode_Error is propagated if the mode of the +file is not In_File. End_Error is propagated if at the end of the file. The current column, line and +page numbers for the file are not affected. + +For an item of type String the following subprograms are provided: + +1 + +2 + +3 + +4 + +5 + +6 + +7 + +8/3 + +9 + +10/3 + +11 + +12/3 + +13/2 + +445 13 December 2012 + +Input-Output of Characters and Strings A.10.7 + + Ada Reference Manual — 2012 Edition + +14 + +15 + +16 + +17 + +17.1/2 + +17.2/2 + +17.3/2 + +18 + +19 + +20 + +21 + +22 + +23 + +24 + +procedure Get(File : in File_Type; Item : out String); +procedure Get(Item : out String); + +Determines the length of the given string and attempts that number of Get operations for +successive characters of the string (in particular, no operation is performed if the string is null). + +procedure Put(File : in File_Type; Item : in String); +procedure Put(Item : in String); + +Determines the length of the given string and attempts that number of Put operations for +successive characters of the string (in particular, no operation is performed if the string is null). + +function Get_Line(File : in File_Type) return String; +function Get_Line return String; + +Returns a result string constructed by reading successive characters from the specified input file, +and assigning them to successive characters of the result string. The result string has a lower +bound of 1 and an upper bound of the number of characters read. Reading stops when the end of +the line is met; Skip_Line is then (in effect) called with a spacing of 1. + +Constraint_Error is raised if the length of the line exceeds Positive'Last; in this case, the line +number and page number are unchanged, and the column number is unspecified but no less than +it was before the call. The exception End_Error is propagated if an attempt is made to skip a file +terminator. + +procedure Get_Line(File : in File_Type; + Item : out String; + Last : out Natural); +procedure Get_Line(Item : out String; + Last : out Natural); + +Reads successive characters from the specified input file and assigns them to successive +characters of the specified string. Reading stops if the end of the string is met. Reading also +stops if the end of the line is met before meeting the end of the string; in this case Skip_Line is +(in effect) called with a spacing of 1. The values of characters not assigned are not specified. + +If characters are read, returns in Last the index value such that Item(Last) is the last character +assigned (the index of the first character assigned is Item'First). If no characters are read, returns +in Last an index value that is one less than Item'First. The exception End_Error is propagated if +an attempt is made to skip a file terminator. + +procedure Put_Line(File : in File_Type; Item : in String); +procedure Put_Line(Item : in String); + +Calls the procedure Put for the given string, and then the procedure New_Line with a spacing of +one. + +Implementation Advice + +The Get_Immediate procedures should be implemented with unbuffered input. For a device such as a +keyboard, input should be “available” if a key has already been typed, whereas for a disk file, input should +always be available except at end of file. For a file associated with a keyboard-like device, any line-editing +features of the underlying operating system should be disabled during the execution of Get_Immediate. + +NOTES +31 Get_Immediate can be used to read a single key from the keyboard “immediately”; that is, without waiting for an end +of line. In a call of Get_Immediate without the parameter Available, the caller will wait until a character is available. + +A.10.7 Input-Output of Characters and Strings + +13 December 2012 446 + + Ada Reference Manual — 2012 Edition + +32 In a literal string parameter of Put, the enclosing string bracket characters are not output. Each doubled string bracket +character in the enclosed string is output as a single string bracket character, as a consequence of the rule for string literals +(see 2.6). + +33 A string read by Get or written by Put can extend over several lines. An implementation is allowed to assume that +certain external files do not contain page terminators, in which case Get_Line and Skip_Line can return as soon as a line +terminator is read. + +A.10.8 Input-Output for Integer Types + +Static Semantics + +The following procedures are defined in the generic packages Integer_IO and Modular_IO, which have to +be instantiated for the appropriate signed integer or modular type respectively (indicated by Num in the +specifications). + +Values are output as decimal or based literals, without low line characters or exponent, and, for +Integer_IO, preceded by a minus sign if negative. The format (which includes any leading spaces and +minus sign) can be specified by an optional field width parameter. Values of widths of fields in output +formats are of the nonnegative integer subtype Field. Values of bases are of the integer subtype +Number_Base. + +subtype Number_Base is Integer range 2 .. 16; + +The default field width and base to be used by output procedures are defined by the following variables +that are declared in the generic packages Integer_IO and Modular_IO: + +Default_Width : Field := Num'Width; +Default_Base : Number_Base := 10; + +The following procedures are provided: + +procedure Get(File : in File_Type; Item : out Num; Width : in Field := 0); +procedure Get(Item : out Num; Width : in Field := 0); + +If the value of the parameter Width is zero, skips any leading blanks, line terminators, or page +terminators, then reads a plus sign if present or (for a signed type only) a minus sign if present, +then reads the longest possible sequence of characters matching the syntax of a numeric literal +without a point. If a nonzero value of Width is supplied, then exactly Width characters are input, +or the characters (possibly none) up to a line terminator, whichever comes first; any skipped +leading blanks are included in the count. + +Returns, in the parameter Item, the value of type Num that corresponds to the sequence input. + +The exception Data_Error is propagated if the sequence of characters read does not form a legal +integer literal or if the value obtained is not of the subtype Num. + +procedure Put(File : in File_Type; + Item : in Num; + Width : in Field := Default_Width; + Base : in Number_Base := Default_Base); + +procedure Put(Item : in Num; + Width : in Field := Default_Width; + Base : in Number_Base := Default_Base); + +25 + +26 + +1 + +2 + +3 + +4 + +5 + +6 + +7 + +8 + +9 + +10/3 + +11 + +Outputs the value of the parameter Item as an integer literal, with no low lines, no exponent, and +no leading zeros (but a single zero for the value zero), and a preceding minus sign for a negative +value. + +12 + +447 13 December 2012 + +Input-Output of Characters and Strings A.10.7 + + + Ada Reference Manual — 2012 Edition + +13 + +14 + +15 + +16 + +17 + +18 + +19 + +20 + +21 + +22 + +23 + +If the resulting sequence of characters to be output has fewer than Width characters, then leading +spaces are first output to make up the difference. + +Uses the syntax for decimal literal if the parameter Base has the value ten (either explicitly or +through Default_Base); otherwise, uses the syntax for based literal, with any letters in upper +case. + +procedure Get(From : in String; Item : out Num; Last : out Positive); + +Reads an integer value from the beginning of the given string, following the same rules as the +Get procedure that reads an integer value from a file, but treating the end of the string as a file +terminator. Returns, in the parameter Item, the value of type Num that corresponds to the +sequence input. Returns in Last the index value such that From(Last) is the last character read. + +The exception Data_Error is propagated if the sequence input does not have the required syntax +or if the value obtained is not of the subtype Num. + +procedure Put(To : out String; + Item : in Num; + Base : in Number_Base := Default_Base); + +Outputs the value of the parameter Item to the given string, following the same rule as for output +to a file, using the length of the given string as the value for Width. + +Integer_Text_IO is a library package that is a nongeneric equivalent to Text_IO.Integer_IO for the +predefined type Integer: + +with Ada.Text_IO; +package Ada.Integer_Text_IO is new Ada.Text_IO.Integer_IO(Integer); + +For each predefined signed integer type, a nongeneric equivalent to Text_IO.Integer_IO is provided, with +names such as Ada.Long_Integer_Text_IO. + +The nongeneric equivalent packages may, but need not, be actual instantiations of the generic package for +the appropriate predefined type. + +Implementation Permissions + +Paragraphs 24 and 25 were deleted. + +Examples + +26/3 + +27 + +subtype Byte_Int is Integer range -127 .. 127; +package Int_IO is new Integer_IO(Byte_Int); use Int_IO; +-- default format used at instantiation, +-- Default_Width = 4, Default_Base = 10 +Put(126); -- "b126" +Put(-126, 7); -- "bbb–126" +Put(126, Width => 13, Base => 2); -- "bbb2#1111110#" + +A.10.9 Input-Output for Real Types + +Static Semantics + +1 + +The following procedures are defined in the generic packages Float_IO, Fixed_IO, and Decimal_IO, +which have to be instantiated for the appropriate floating point, ordinary fixed point, or decimal fixed +point type respectively (indicated by Num in the specifications). + +A.10.8 Input-Output for Integer Types + +13 December 2012 448 + + Values are output as decimal literals without low line characters. The format of each value output consists +of a Fore field, a decimal point, an Aft field, and (if a nonzero Exp parameter is supplied) the letter E and +an Exp field. The two possible formats thus correspond to: + +Ada Reference Manual — 2012 Edition + +Fore . Aft + +and to: + +Fore . Aft E Exp + +without any spaces between these fields. The Fore field may include leading spaces, and a minus sign for +negative values. The Aft field includes only decimal digits (possibly with trailing zeros). The Exp field +includes the sign (plus or minus) and the exponent (possibly with leading zeros). + +For floating point types, the default lengths of these fields are defined by the following variables that are +declared in the generic package Float_IO: + +Default_Fore : Field := 2; +Default_Aft : Field := Num'Digits-1; +Default_Exp : Field := 3; + +For ordinary or decimal fixed point types, the default lengths of these fields are defined by the following +variables that are declared in the generic packages Fixed_IO and Decimal_IO, respectively: + +Default_Fore : Field := Num'Fore; +Default_Aft : Field := Num'Aft; +Default_Exp : Field := 0; + +The following procedures are provided: + +procedure Get(File : in File_Type; Item : out Num; Width : in Field := 0); +procedure Get(Item : out Num; Width : in Field := 0); + +If the value of the parameter Width is zero, skips any leading blanks, line terminators, or page +terminators, then reads the longest possible sequence of characters matching the syntax of any of +the following (see 2.4): +• [+|–]numeric_literal +• [+|–]numeral.[exponent] +• [+|–].numeral[exponent] +• [+|–]base#based_numeral.#[exponent] +• [+|–]base#.based_numeral#[exponent] + +If a nonzero value of Width is supplied, then exactly Width characters are input, or the +characters (possibly none) up to a line terminator, whichever comes first; any skipped leading +blanks are included in the count. + +Returns in the parameter Item the value of type Num that corresponds to the sequence input, +preserving the sign (positive if none has been specified) of a zero value if Num is a floating +point type and Num'Signed_Zeros is True. + +The exception Data_Error is propagated if the sequence input does not have the required syntax +or if the value obtained is not of the subtype Num. + +2 + +3 + +4 + +5 + +6 + +7 + +8 + +9 + +10 + +11 + +12 + +13 + +14 + +15 + +16 + +17 + +18 + +19 + +20 + +21 + +449 13 December 2012 + +Input-Output for Real Types A.10.9 + + 22 + +23 + +24 + +25 + +26 + +27 + +28 + +29 + +30 + +31 + +32 + +33 + +Ada Reference Manual — 2012 Edition + +procedure Put(File : in File_Type; + Item : in Num; + Fore : in Field := Default_Fore; + Aft : in Field := Default_Aft; + Exp : in Field := Default_Exp); + +procedure Put(Item : in Num; + Fore : in Field := Default_Fore; + Aft : in Field := Default_Aft; + Exp : in Field := Default_Exp); + +Outputs the value of the parameter Item as a decimal literal with the format defined by Fore, Aft +and Exp. If the value is negative, or if Num is a floating point type where Num'Signed_Zeros is +True and the value is a negatively signed zero, then a minus sign is included in the integer part. +If Exp has the value zero, then the integer part to be output has as many digits as are needed to +represent the integer part of the value of Item, overriding Fore if necessary, or consists of the +digit zero if the value of Item has no integer part. + +If Exp has a value greater than zero, then the integer part to be output has a single digit, which is +nonzero except for the value 0.0 of Item. + +In both cases, however, if the integer part to be output has fewer than Fore characters, including +any minus sign, then leading spaces are first output to make up the difference. The number of +digits of the fractional part is given by Aft, or is one if Aft equals zero. The value is rounded; a +value of exactly one half in the last place is rounded away from zero. + +If Exp has the value zero, there is no exponent part. If Exp has a value greater than zero, then the +exponent part to be output has as many digits as are needed to represent the exponent part of the +value of Item (for which a single digit integer part is used), and includes an initial sign (plus or +minus). If the exponent part to be output has fewer than Exp characters, including the sign, then +leading zeros precede the digits, to make up the difference. For the value 0.0 of Item, the +exponent has the value zero. + +procedure Get(From : in String; Item : out Num; Last : out Positive); + +Reads a real value from the beginning of the given string, following the same rule as the Get +procedure that reads a real value from a file, but treating the end of the string as a file terminator. +Returns, in the parameter Item, the value of type Num that corresponds to the sequence input. +Returns in Last the index value such that From(Last) is the last character read. + +The exception Data_Error is propagated if the sequence input does not have the required syntax, +or if the value obtained is not of the subtype Num. + +procedure Put(To : out String; + Item : in Num; + Aft : in Field := Default_Aft; + Exp : in Field := Default_Exp); + +Outputs the value of the parameter Item to the given string, following the same rule as for output +to a file, using a value for Fore such that the sequence of characters output exactly fills the +string, including any leading spaces. + +Float_Text_IO is a library package that is a nongeneric equivalent to Text_IO.Float_IO for the predefined +type Float: + +with Ada.Text_IO; +package Ada.Float_Text_IO is new Ada.Text_IO.Float_IO(Float); + +A.10.9 Input-Output for Real Types + +13 December 2012 450 + + + Ada Reference Manual — 2012 Edition + +For each predefined floating point type, a nongeneric equivalent to Text_IO.Float_IO is provided, with +names such as Ada.Long_Float_Text_IO. + +Implementation Permissions + +An implementation may extend Get and Put for floating point types to support special values such as +infinities and NaNs. + +The implementation of Put need not produce an output value with greater accuracy than is supported for +the base subtype. The additional accuracy, if any, of the value produced by Put when the number of +requested digits in the integer and fractional parts exceeds the required accuracy is implementation +defined. + +The nongeneric equivalent packages may, but need not, be actual instantiations of the generic package for +the appropriate predefined type. + +NOTES +34 For an item with a positive value, if output to a string exactly fills the string without leading spaces, then output of the +corresponding negative value will propagate Layout_Error. + +35 The rules for the Value attribute (see 3.5) and the rules for Get are based on the same set of formats. + +Examples + +This paragraph was deleted. +package Real_IO is new Float_IO(Real); use Real_IO; +-- default format used at instantiation, Default_Exp = 3 +X : Real := -123.4567; -- digits 8 (see 3.5.7) +Put(X); -- default format +"–1.2345670E+02" +Put(X, Fore => 5, Aft => 3, Exp => 2); -- "bbb–1.235E+2" +Put(X, 5, 3, 0); + +-- "b–123.457" + +A.10.10 Input-Output for Enumeration Types + +Static Semantics + +The following procedures are defined in the generic package Enumeration_IO, which has to be instantiated +for the appropriate enumeration type (indicated by Enum in the specification). + +Values are output using either upper or lower case letters for identifiers. This is specified by the parameter +Set, which is of the enumeration type Type_Set. + +type Type_Set is (Lower_Case, Upper_Case); + +The format (which includes any trailing spaces) can be specified by an optional field width parameter. The +default field width and letter case are defined by the following variables that are declared in the generic +package Enumeration_IO: + +Default_Width : Field := 0; +Default_Setting : Type_Set := Upper_Case; + +The following procedures are provided: + +procedure Get(File : in File_Type; Item : out Enum); +procedure Get(Item : out Enum); + +After skipping any leading blanks, line terminators, or page terminators, reads an identifier +according to the syntax of this lexical element (lower and upper case being considered +equivalent), or a character literal according to the syntax of this lexical element (including the + +451 13 December 2012 + +Input-Output for Real Types A.10.9 + +34 + +35 + +36 + +37 + +38 + +39 + +40/1 + +41 + +42 + +43 + +1 + +2 + +3 + +4 + +5 + +6 + +7 + +8 + + Ada Reference Manual — 2012 Edition + +apostrophes). Returns, in the parameter Item, the value of type Enum that corresponds to the +sequence input. + +The exception Data_Error is propagated if the sequence input does not have the required syntax, +or if the identifier or character literal does not correspond to a value of the subtype Enum. + +procedure Put(File : in File_Type; + Item : in Enum; + Width : in Field := Default_Width; + Set : in Type_Set := Default_Setting); + +procedure Put(Item : in Enum; + Width : in Field := Default_Width; + Set : in Type_Set := Default_Setting); + +Outputs the value of the parameter Item as an enumeration literal (either an identifier or a +character literal). The optional parameter Set indicates whether lower case or upper case is used +for identifiers; it has no effect for character literals. If the sequence of characters produced has +fewer than Width characters, then trailing spaces are finally output to make up the difference. If +Enum is a character type, the sequence of characters produced is as for Enum'Image(Item), as +modified by the Width and Set parameters. + +procedure Get(From : in String; Item : out Enum; Last : out Positive); + +Reads an enumeration value from the beginning of the given string, following the same rule as +the Get procedure that reads an enumeration value from a file, but treating the end of the string +as a file terminator. Returns, in the parameter Item, the value of type Enum that corresponds to +the sequence input. Returns in Last the index value such that From(Last) is the last character +read. + +The exception Data_Error is propagated if the sequence input does not have the required syntax, +or if the identifier or character literal does not correspond to a value of the subtype Enum. + +procedure Put(To : out String; + Item : in Enum; + Set : in Type_Set := Default_Setting); + +Outputs the value of the parameter Item to the given string, following the same rule as for output +to a file, using the length of the given string as the value for Width. + +9 + +10 + +11 + +12 + +13 + +14 + +15 + +16 + +17/1 + +Although the specification of the generic package Enumeration_IO would allow instantiation for an +integer type, this is not the intended purpose of this generic package, and the effect of such instantiations is +not defined by the language. + +18 + +19 + +20 + +21 + +NOTES +36 There is a difference between Put defined for characters, and for enumeration values. Thus + + Ada.Text_IO.Put('A'); -- outputs the character A + package Char_IO is new Ada.Text_IO.Enumeration_IO(Character); + Char_IO.Put('A'); -- outputs the character 'A', between apostrophes + +37 The type Boolean is an enumeration type, hence Enumeration_IO can be instantiated for this type. + +A.10.11 Input-Output for Bounded Strings + +1/2 + +The package Text_IO.Bounded_IO provides input-output in human-readable form for Bounded_Strings. + +A.10.10 Input-Output for Enumeration Types + +13 December 2012 452 + + + Ada Reference Manual — 2012 Edition + +The generic library package Text_IO.Bounded_IO has the following declaration: + +Static Semantics + +with Ada.Strings.Bounded; +generic + with package Bounded is + new Ada.Strings.Bounded.Generic_Bounded_Length (<>); +package Ada.Text_IO.Bounded_IO is + procedure Put + (File : in File_Type; + Item : in Bounded.Bounded_String); + procedure Put + (Item : in Bounded.Bounded_String); + procedure Put_Line + (File : in File_Type; + Item : in Bounded.Bounded_String); + procedure Put_Line + (Item : in Bounded.Bounded_String); + function Get_Line + (File : in File_Type) + return Bounded.Bounded_String; + function Get_Line + return Bounded.Bounded_String; + procedure Get_Line + (File : in File_Type; Item : out Bounded.Bounded_String); + procedure Get_Line + (Item : out Bounded.Bounded_String); +end Ada.Text_IO.Bounded_IO; + +For an item of type Bounded_String, the following subprograms are provided: + +procedure Put + (File : in File_Type; + Item : in Bounded.Bounded_String); + +Equivalent to Text_IO.Put (File, Bounded.To_String(Item)); + +procedure Put + (Item : in Bounded.Bounded_String); + +Equivalent to Text_IO.Put (Bounded.To_String(Item)); + +procedure Put_Line + (File : in File_Type; + Item : in Bounded.Bounded_String); + +Equivalent to Text_IO.Put_Line (File, Bounded.To_String(Item)); + +procedure Put_Line + (Item : in Bounded.Bounded_String); + +Equivalent to Text_IO.Put_Line (Bounded.To_String(Item)); + +function Get_Line + (File : in File_Type) + return Bounded.Bounded_String; + +Returns Bounded.To_Bounded_String(Text_IO.Get_Line(File)); + +function Get_Line + return Bounded.Bounded_String; + +Returns Bounded.To_Bounded_String(Text_IO.Get_Line); + +2/2 + +3/2 + +4/2 + +5/2 + +6/2 + +7/2 + +8/2 + +9/2 + +10/2 + +11/2 + +12/2 + +13/2 + +14/2 + +15/2 + +16/2 + +17/2 + +18/2 + +19/2 + +20/2 + +21/2 + +22/2 + +23/2 + +24/2 + +25/2 + +453 13 December 2012 + +Input-Output for Bounded Strings A.10.11 + + Ada Reference Manual — 2012 Edition + +26/2 + +27/2 + +28/2 + +29/2 + +procedure Get_Line + (File : in File_Type; Item : out Bounded.Bounded_String); + +Equivalent to Item := Get_Line (File); + +procedure Get_Line + (Item : out Bounded.Bounded_String); + +Equivalent to Item := Get_Line; + +A.10.12 Input-Output for Unbounded Strings + +1/2 + +The package Text_IO.Unbounded_IO provides +Unbounded_Strings. + +input-output + +in human-readable + +form + +for + +The library package Text_IO.Unbounded_IO has the following declaration: + +Static Semantics + +with Ada.Strings.Unbounded; +package Ada.Text_IO.Unbounded_IO is + procedure Put + (File : in File_Type; + Item : in Strings.Unbounded.Unbounded_String); + procedure Put + (Item : in Strings.Unbounded.Unbounded_String); + procedure Put_Line + (File : in File_Type; + Item : in Strings.Unbounded.Unbounded_String); + procedure Put_Line + (Item : in Strings.Unbounded.Unbounded_String); + function Get_Line + (File : in File_Type) + return Strings.Unbounded.Unbounded_String; + function Get_Line + return Strings.Unbounded.Unbounded_String; + procedure Get_Line + (File : in File_Type; Item : out Strings.Unbounded.Unbounded_String); + procedure Get_Line + (Item : out Strings.Unbounded.Unbounded_String); +end Ada.Text_IO.Unbounded_IO; + +For an item of type Unbounded_String, the following subprograms are provided: + +procedure Put + (File : in File_Type; + Item : in Strings.Unbounded.Unbounded_String); + +Equivalent to Text_IO.Put (File, Strings.Unbounded.To_String(Item)); + +procedure Put + (Item : in Strings.Unbounded.Unbounded_String); + +Equivalent to Text_IO.Put (Strings.Unbounded.To_String(Item)); + +procedure Put_Line + (File : in File_Type; + Item : in Strings.Unbounded.Unbounded_String); + +Equivalent to Text_IO.Put_Line (File, Strings.Unbounded.To_String(Item)); + +2/2 + +3/2 + +4/2 + +5/2 + +6/2 + +7/2 + +8/2 + +9/2 + +10/2 + +11/2 + +12/2 + +13/2 + +14/2 + +15/2 + +16/2 + +17/2 + +18/2 + +19/2 + +A.10.11 Input-Output for Bounded Strings + +13 December 2012 454 + + Ada Reference Manual — 2012 Edition + +procedure Put_Line + (Item : in Strings.Unbounded.Unbounded_String); + +Equivalent to Text_IO.Put_Line (Strings.Unbounded.To_String(Item)); + +function Get_Line + (File : in File_Type) + return Strings.Unbounded.Unbounded_String; + +Returns Strings.Unbounded.To_Unbounded_String(Text_IO.Get_Line(File)); + +function Get_Line + return Strings.Unbounded.Unbounded_String; + +Returns Strings.Unbounded.To_Unbounded_String(Text_IO.Get_Line); + +procedure Get_Line + (File : in File_Type; Item : out Strings.Unbounded.Unbounded_String); + +Equivalent to Item := Get_Line (File); + +procedure Get_Line + (Item : out Strings.Unbounded.Unbounded_String); + +Equivalent to Item := Get_Line; + +A.11 Wide Text Input-Output and Wide Wide Text Input-Output + +The packages Wide_Text_IO and Wide_Wide_Text_IO provide facilities for input and output in human- +readable form. Each file is read or written sequentially, as a sequence of wide characters (or wide wide +characters) grouped into lines, and as a sequence of lines grouped into pages. + +Static Semantics + +The specification of package Wide_Text_IO is the same as that for Text_IO, except that in each Get, +Look_Ahead, Get_Immediate, Get_Line, Put, and Put_Line subprogram, any occurrence of Character is +replaced by Wide_Character, and any occurrence of String is replaced by Wide_String. Nongeneric +equivalents of Wide_Text_IO.Integer_IO and Wide_Text_IO.Float_IO are provided (as for Text_IO) for +each predefined numeric type, with names such as Ada.Integer_Wide_Text_IO, Ada.Long_Integer_- +Wide_Text_IO, Ada.Float_Wide_Text_IO, Ada.Long_Float_Wide_Text_IO. + +The specification of package Wide_Wide_Text_IO is the same as that for Text_IO, except that in each +Get, Look_Ahead, Get_Immediate, Get_Line, Put, and Put_Line subprogram, any occurrence of Character +is replaced by Wide_Wide_Character, and any occurrence of String is replaced by Wide_Wide_String. +Nongeneric equivalents of Wide_Wide_Text_IO.Integer_IO and Wide_Wide_Text_IO.Float_IO are +provided (as for Text_IO) for each predefined numeric type, with names such as Ada.Integer_- +Wide_Wide_Text_IO, +Ada.Float_Wide_Wide_Text_IO, +Ada.Long_Float_Wide_Wide_Text_IO. + +Ada.Long_Integer_Wide_Wide_Text_IO, + +specification of package Wide_Text_IO.Wide_Bounded_IO + +The +for +Text_IO.Bounded_IO, except that any occurrence of Bounded_String is replaced by Bounded_Wide_- +String, and any occurrence of package Bounded is replaced by Wide_Bounded. The specification of +package Wide_Wide_Text_IO.Wide_Wide_Bounded_IO is the same as that for Text_IO.Bounded_IO, +except that any occurrence of Bounded_String is replaced by Bounded_Wide_Wide_String, and any +occurrence of package Bounded is replaced by Wide_Wide_Bounded. + +same as + +that + +the + +is + +20/2 + +21/2 + +22/2 + +23/2 + +24/2 + +25/2 + +26/2 + +27/2 + +28/2 + +29/2 + +1/2 + +2/2 + +3/2 + +4/3 + +The specification of package Wide_Text_IO.Wide_Unbounded_IO is the same as that for Text_IO.- +Unbounded_IO, except that any occurrence of Unbounded_String is replaced by Unbounded_Wide_- +String, and any occurrence of package Unbounded is replaced by Wide_Unbounded. The specification of + +5/3 + +455 13 December 2012 + +Input-Output for Unbounded Strings A.10.12 + + Ada Reference Manual — 2012 Edition + +package Wide_Wide_Text_IO.Wide_Wide_Unbounded_IO +for +Text_IO.Unbounded_IO, except that any occurrence of Unbounded_String is replaced by Unbounded_- +Wide_Wide_String, and any occurrence of package Unbounded is replaced by Wide_Wide_Unbounded. + +same + +that + +the + +as + +is + +A.12 Stream Input-Output + +1/2 + +packages Streams.Stream_IO, Text_IO.Text_Streams, Wide_Text_IO.Text_Streams, + +The +Wide_Wide_Text_IO.Text_Streams provide stream-oriented operations on files. + +and + +A.12.1 The Package Streams.Stream_IO + +1 + +The subprograms in the child package Streams.Stream_IO provide control over stream files. Access to a +stream file is either sequential, via a call on Read or Write to transfer an array of stream elements, or +positional (if supported by the implementation for the given file), by specifying a relative index for an +element. Since a stream file can be converted to a Stream_Access value, calling stream-oriented attribute +subprograms of different element types with the same Stream_Access value provides heterogeneous input- +output. See 13.13 for a general discussion of streams. + +1.1/1 + +2 + +3/3 + +4 + +5 + +6 + +7 + +8 + +9 + +10 + +11 + +12 + +13 + +Static Semantics + +The elements of a stream file are stream elements. If positioning is supported for the specified external +file, a current index and current size are maintained for the file as described in A.8. If positioning is not +supported, a current index is not maintained, and the current size is implementation defined. + +The library package Streams.Stream_IO has the following declaration: + +with Ada.IO_Exceptions; +package Ada.Streams.Stream_IO is + pragma Preelaborate(Stream_IO); + type Stream_Access is access all Root_Stream_Type'Class; + type File_Type is limited private; + type File_Mode is (In_File, Out_File, Append_File); + type Count is range 0 .. implementation-defined; + subtype Positive_Count is Count range 1 .. Count'Last; + -- Index into file, in stream elements. + procedure Create (File : in out File_Type; + Mode : in File_Mode := Out_File; + Name : in String := ""; + Form : in String := ""); + procedure Open (File : in out File_Type; + Mode : in File_Mode; + Name : in String; + Form : in String := ""); + procedure Close (File : in out File_Type); + procedure Delete (File : in out File_Type); + procedure Reset (File : in out File_Type; Mode : in File_Mode); + procedure Reset (File : in out File_Type); + function Mode (File : in File_Type) return File_Mode; + function Name (File : in File_Type) return String; + function Form (File : in File_Type) return String; + function Is_Open (File : in File_Type) return Boolean; + function End_Of_File (File : in File_Type) return Boolean; + function Stream (File : in File_Type) return Stream_Access; + -- Return stream access for use with T'Input and T'Output + +A.11 Wide Text Input-Output and Wide Wide Text Input-Output + +13 December 2012 456 + + Ada Reference Manual — 2012 Edition + +This paragraph was deleted. + -- Read array of stream elements from file + procedure Read (File : in File_Type; + Item : out Stream_Element_Array; + Last : out Stream_Element_Offset; + From : in Positive_Count); + procedure Read (File : in File_Type; + Item : out Stream_Element_Array; + Last : out Stream_Element_Offset); +This paragraph was deleted. + -- Write array of stream elements into file + procedure Write (File : in File_Type; + Item : in Stream_Element_Array; + To : in Positive_Count); + procedure Write (File : in File_Type; + Item : in Stream_Element_Array); +This paragraph was deleted. + -- Operations on position within file + procedure Set_Index(File : in File_Type; To : in Positive_Count); + function Index(File : in File_Type) return Positive_Count; + function Size (File : in File_Type) return Count; + procedure Set_Mode(File : in out File_Type; Mode : in File_Mode); + procedure Flush(File : in File_Type); + -- exceptions + Status_Error : exception renames IO_Exceptions.Status_Error; + Mode_Error : exception renames IO_Exceptions.Mode_Error; + Name_Error : exception renames IO_Exceptions.Name_Error; + Use_Error : exception renames IO_Exceptions.Use_Error; + Device_Error : exception renames IO_Exceptions.Device_Error; + End_Error : exception renames IO_Exceptions.End_Error; + Data_Error : exception renames IO_Exceptions.Data_Error; +private + ... -- not specified by the language +end Ada.Streams.Stream_IO; + +The type File_Type needs finalization (see 7.6). + +The subprograms given in subclause A.8.2 for the control of external files (Create, Open, Close, Delete, +Reset, Mode, Name, Form, and Is_Open) are available for stream files. + +The End_Of_File function: + +• Propagates Mode_Error if the mode of the file is not In_File; +• If positioning is supported for the given external file, the function returns True if the current + +index exceeds the size of the external file; otherwise, it returns False; + +• If positioning is not supported for the given external file, the function returns True if no more + +elements can be read from the given file; otherwise, it returns False. + +The Set_Mode procedure sets the mode of the file. If the new mode is Append_File, the file is positioned +to its end; otherwise, the position in the file is unchanged. + +The Flush procedure synchronizes the external file with the internal file (by flushing any internal buffers) +without closing the file or changing the position. Mode_Error is propagated if the mode of the file is +In_File. + +457 13 December 2012 + +The Package Streams.Stream_IO A.12.1 + +14/1 + +15 + +16 + +17/1 + +18 + +19 + +20/1 + +21 + +22 + +23 + +24 + +25/1 + +26 + +27 + +27.1/2 + +28/2 + +28.1/2 + +28.2/2 + +28.3/3 + +28.4/3 + +28.5/2 + +28.6/1 + + Ada Reference Manual — 2012 Edition + +29/1 + +30/2 + +The Stream function returns a Stream_Access result from a File_Type object, thus allowing the stream- +oriented attributes Read, Write, Input, and Output to be used on the same file for multiple types. Stream +propagates Status_Error if File is not open. + +The procedures Read and Write are equivalent to the corresponding operations in the package Streams. +Read propagates Mode_Error if the mode of File is not In_File. Write propagates Mode_Error if the mode +of File is not Out_File or Append_File. The Read procedure with a Positive_Count parameter starts +reading at the specified index. The Write procedure with a Positive_Count parameter starts writing at the +specified index. For a file that supports positioning, Read without a Positive_Count parameter starts +reading at the current index, and Write without a Positive_Count parameter starts writing at the current +index. + +30.1/1 + +The Size function returns the current size of the file. + +31/1 + +The Index function returns the current index. + +32 + +The Set_Index procedure sets the current index to the specified value. + +32.1/1 + +If positioning is supported for the external file, the current index is maintained as follows: + +32.2/1 + +• For Open and Create, if the Mode parameter is Append_File, the current index is set to the + +current size of the file plus one; otherwise, the current index is set to one. + +32.3/1 + +• For Reset, if the Mode parameter is Append_File, or no Mode parameter is given and the current +mode is Append_File, the current index is set to the current size of the file plus one; otherwise, +the current index is set to one. + +32.4/1 + +• For Set_Mode, if the new mode is Append_File, the current index is set to current size plus one; + +otherwise, the current index is unchanged. + +32.5/1 + +• For Read and Write without a Positive_Count parameter, the current index is incremented by the + +number of stream elements read or written. + +32.6/1 + +• For Read and Write with a Positive_Count parameter, the value of the current index is set to the +value of the Positive_Count parameter plus the number of stream elements read or written. + +33 + +If positioning is not supported for the given file, then a call of Index or Set_Index propagates Use_Error. +Similarly, a call of Read or Write with a Positive_Count parameter propagates Use_Error. + +Paragraphs 34 through 36 were deleted. + +36.1/1 + +If the File_Type object passed to the Stream function is later closed or finalized, and the stream-oriented +attributes are subsequently called (explicitly or implicitly) on the Stream_Access value returned by +Stream, execution is erroneous. This rule applies even if the File_Type object was opened again after it +had been closed. + +Erroneous Execution + +1 + +2 + +3 + +A.12.2 The Package Text_IO.Text_Streams + +The package Text_IO.Text_Streams provides a function for treating a text file as a stream. + +The library package Text_IO.Text_Streams has the following declaration: + +with Ada.Streams; +package Ada.Text_IO.Text_Streams is + type Stream_Access is access all Streams.Root_Stream_Type'Class; + +Static Semantics + +A.12.1 The Package Streams.Stream_IO + +13 December 2012 458 + + Ada Reference Manual — 2012 Edition + + function Stream (File : in File_Type) return Stream_Access; +end Ada.Text_IO.Text_Streams; + +The Stream function has the same effect as the corresponding function in Streams.Stream_IO. + +NOTES +38 The ability to obtain a stream for a text file allows Current_Input, Current_Output, and Current_Error to be processed +with the functionality of streams, including the mixing of text and binary input-output, and the mixing of binary input- +output for different types. + +39 Performing operations on the stream associated with a text file does not affect the column, line, or page counts. + +A.12.3 The Package Wide_Text_IO.Text_Streams + +The package Wide_Text_IO.Text_Streams provides a function for treating a wide text file as a stream. + +Static Semantics + +The library package Wide_Text_IO.Text_Streams has the following declaration: + +with Ada.Streams; +package Ada.Wide_Text_IO.Text_Streams is + type Stream_Access is access all Streams.Root_Stream_Type'Class; + function Stream (File : in File_Type) return Stream_Access; +end Ada.Wide_Text_IO.Text_Streams; + +The Stream function has the same effect as the corresponding function in Streams.Stream_IO. + +4 + +5 + +6 + +7 + +1 + +2 + +3 + +4 + +5 + +A.12.4 The Package Wide_Wide_Text_IO.Text_Streams + +The package Wide_Wide_Text_IO.Text_Streams provides a function for treating a wide wide text file as a +stream. + +1/2 + +Static Semantics + +The library package Wide_Wide_Text_IO.Text_Streams has the following declaration: + +with Ada.Streams; +package Ada.Wide_Wide_Text_IO.Text_Streams is + type Stream_Access is access all Streams.Root_Stream_Type'Class; + function Stream (File : in File_Type) return Stream_Access; +end Ada.Wide_Wide_Text_IO.Text_Streams; + +The Stream function has the same effect as the corresponding function in Streams.Stream_IO. + +A.13 Exceptions in Input-Output + +The package IO_Exceptions defines the exceptions needed by the predefined input-output packages. + +The library package IO_Exceptions has the following declaration: + +package Ada.IO_Exceptions is + pragma Pure(IO_Exceptions); + +Static Semantics + +2/2 + +3/2 + +4/2 + +5/2 + +1 + +2 + +3 + +459 13 December 2012 + +The Package Text_IO.Text_Streams A.12.2 + + 4 + +5 + +6 + +7 + +8 + +9 + +10 + +11 + +12 + +13 + +14 + +Ada Reference Manual — 2012 Edition + + Status_Error : exception; + Mode_Error : exception; + Name_Error : exception; + Use_Error : exception; + Device_Error : exception; + End_Error : exception; + Data_Error : exception; + Layout_Error : exception; +end Ada.IO_Exceptions; + +If more than one error condition exists, the corresponding exception that appears earliest in the following +list is the one that is propagated. + +The exception Status_Error is propagated by an attempt to operate upon a file that is not open, and by an +attempt to open a file that is already open. + +The exception Mode_Error is propagated by an attempt to read from, or test for the end of, a file whose +current mode is Out_File or Append_File, and also by an attempt to write to a file whose current mode is +In_File. In the case of Text_IO, the exception Mode_Error is also propagated by specifying a file whose +current mode is Out_File or Append_File in a call of Set_Input, Skip_Line, End_Of_Line, Skip_Page, or +End_Of_Page; and by specifying a file whose current mode is In_File in a call of Set_Output, +Set_Line_Length, Set_Page_Length, Line_Length, Page_Length, New_Line, or New_Page. + +The exception Name_Error is propagated by a call of Create or Open if the string given for the parameter +Name does not allow the identification of an external file. For example, this exception is propagated if the +string is improper, or, alternatively, if either none or more than one external file corresponds to the string. + +The exception Use_Error is propagated if an operation is attempted that is not possible for reasons that +depend on characteristics of the external file. For example, this exception is propagated by the procedure +Create, among other circumstances, if the given mode is Out_File but the form specifies an input only +device, if the parameter Form specifies invalid access rights, or if an external file with the given name +already exists and overwriting is not allowed. + +The exception Device_Error is propagated if an input-output operation cannot be completed because of a +malfunction of the underlying system. + +The exception End_Error is propagated by an attempt to skip (read past) the end of a file. + +The exception Data_Error can be propagated by the procedure Read (or by the Read attribute) if the +element read cannot be interpreted as a value of the required subtype. This exception is also propagated by +a procedure Get (defined in the package Text_IO) if the input character sequence fails to satisfy the +required syntax, or if the value input does not belong to the range of the required subtype. + +The exception Layout_Error is propagated (in text input-output) by Col, Line, or Page if the value returned +exceeds Count'Last. The exception Layout_Error is also propagated on output by an attempt to set column +or line numbers in excess of specified maximum line or page lengths, respectively (excluding the +unbounded cases). It is also propagated by an attempt to Put too many characters to a string. + +14.1/3 + +These exceptions are also propagated by various other language-defined packages and operations, see the +definition of those entities for other reasons that these exceptions are propagated. + +15 + +The implementation shall document the conditions under which Name_Error, Use_Error and Device_Error +are propagated. + +Documentation Requirements + +A.13 Exceptions in Input-Output + +13 December 2012 460 + + Ada Reference Manual — 2012 Edition + +If the associated check is too complex, an implementation need not propagate Data_Error as part of a +procedure Read (or the Read attribute) if the value read cannot be interpreted as a value of the required +subtype. + +Implementation Permissions + +If the element read by the procedure Read (or by the Read attribute) cannot be interpreted as a value of the +required subtype, but this is not detected and Data_Error is not propagated, then the resulting value can be +abnormal, and subsequent references to the value can lead to erroneous execution, as explained in 13.9.1. + +Erroneous Execution + +A.14 File Sharing + +Dynamic Semantics + +It is not specified by the language whether the same external file can be associated with more than one file +object. If such sharing is supported by the implementation, the following effects are defined: + +• Operations on one text file object do not affect the column, line, and page numbers of any other + +file object. + +• This paragraph was deleted. +• For direct and stream files, the current index is a property of each file object; an operation on + +one file object does not affect the current index of any other file object. + +• For direct and stream files, the current size of the file is a property of the external file. + +All other effects are identical. + +A.15 The Package Command_Line + +The package Command_Line allows a program to obtain the values of its arguments and to set the exit +status code to be returned on normal termination. + +The library package Ada.Command_Line has the following declaration: + +Static Semantics + +package Ada.Command_Line is + pragma Preelaborate(Command_Line); + function Argument_Count return Natural; + function Argument (Number : in Positive) return String; + function Command_Name return String; + type Exit_Status is implementation-defined integer type; + Success : constant Exit_Status; + Failure : constant Exit_Status; + procedure Set_Exit_Status (Code : in Exit_Status); +private + ... -- not specified by the language +end Ada.Command_Line; + +16 + +17 + +1 + +2 + +3/1 + +4 + +5 + +6 + +1 + +2 + +3 + +4 + +5 + +6 + +7 + +8 + +9 + +10 + +461 13 December 2012 + +Exceptions in Input-Output A.13 + + + Ada Reference Manual — 2012 Edition + +11 + +12/3 + +13 + +14 + +15 + +16/3 + +16.1/1 + +17 + +18 + +19 + +20 + +21 + +22 + +function Argument_Count return Natural; + +If the external execution environment supports passing arguments to a program, then +Argument_Count returns the number of arguments passed to the program invoking the function. +Otherwise, it returns 0. The meaning of “number of arguments” is implementation defined. + +function Argument (Number : in Positive) return String; + +If the external execution environment supports passing arguments to a program, then Argument +returns an implementation-defined value corresponding to the argument at relative position +Number. If Number is outside the range 1..Argument_Count, then Constraint_Error is +propagated. + +function Command_Name return String; + +If the external execution environment supports passing arguments to a program, then +Command_Name returns an implementation-defined value corresponding to the name of the +command invoking the program; otherwise, Command_Name returns the null string. + +type Exit_Status is implementation-defined integer type; + +The type Exit_Status represents the range of exit status values supported by the external +execution environment. The constants Success and Failure correspond to success and failure, +respectively. + +procedure Set_Exit_Status (Code : in Exit_Status); + +If the external execution environment supports returning an exit status from a program, then +Set_Exit_Status sets Code as the status. Normal termination of a program returns as the exit +status the value most recently set by Set_Exit_Status, or, if no such value has been set, then the +value Success. If a program terminates abnormally, the status set by Set_Exit_Status is ignored, +and an implementation-defined exit status value is set. + +If the external execution environment does not support returning an exit value from a program, +then Set_Exit_Status does nothing. + +Implementation Permissions + +An alternative declaration is allowed for package Command_Line if different functionality is appropriate +for the external execution environment. + +NOTES +40 Argument_Count, Argument, and Command_Name correspond to the C language's argc, argv[n] (for n>0) and +argv[0], respectively. + +A.16 The Package Directories + +1/2 + +The package Directories provides operations for manipulating files and directories, and their names. + +Static Semantics + +2/2 + +3/2 + +4/2 + +5/2 + +The library package Directories has the following declaration: + +with Ada.IO_Exceptions; +with Ada.Calendar; +package Ada.Directories is + -- Directory and file operations: + function Current_Directory return String; + +A.15 The Package Command_Line + +13 December 2012 462 + + Ada Reference Manual — 2012 Edition + + procedure Set_Directory (Directory : in String); + procedure Create_Directory (New_Directory : in String; + Form : in String := ""); + procedure Delete_Directory (Directory : in String); + procedure Create_Path (New_Directory : in String; + Form : in String := ""); + procedure Delete_Tree (Directory : in String); + procedure Delete_File (Name : in String); + procedure Rename (Old_Name, New_Name : in String); + procedure Copy_File (Source_Name, + Target_Name : in String; + Form : in String := ""); + -- File and directory name operations: + function Full_Name (Name : in String) return String; + function Simple_Name (Name : in String) return String; + function Containing_Directory (Name : in String) return String; + function Extension (Name : in String) return String; + function Base_Name (Name : in String) return String; + function Compose (Containing_Directory : in String := ""; + Name : in String; + Extension : in String := "") return String; + type Name_Case_Kind is + (Unknown, Case_Sensitive, Case_Insensitive, Case_Preserving); + function Name_Case_Equivalence (Name : in String) return Name_Case_Kind; + -- File and directory queries: + type File_Kind is (Directory, Ordinary_File, Special_File); + type File_Size is range 0 .. implementation-defined; + function Exists (Name : in String) return Boolean; + function Kind (Name : in String) return File_Kind; + function Size (Name : in String) return File_Size; + function Modification_Time (Name : in String) return Ada.Calendar.Time; + -- Directory searching: + type Directory_Entry_Type is limited private; + type Filter_Type is array (File_Kind) of Boolean; + type Search_Type is limited private; + procedure Start_Search (Search : in out Search_Type; + Directory : in String; + Pattern : in String; + Filter : in Filter_Type := (others => True)); + procedure End_Search (Search : in out Search_Type); + function More_Entries (Search : in Search_Type) return Boolean; + procedure Get_Next_Entry (Search : in out Search_Type; + Directory_Entry : out Directory_Entry_Type); + procedure Search ( + Directory : in String; + Pattern : in String; + Filter : in Filter_Type := (others => True); + Process : not null access procedure ( + Directory_Entry : in Directory_Entry_Type)); + -- Operations on Directory Entries: + +6/2 + +7/2 + +8/2 + +9/2 + +10/2 + +11/2 + +12/2 + +13/2 + +14/2 + +15/2 + +16/2 + +17/2 + +18/2 + +19/2 + +20/2 + +20.1/3 + +20.2/3 + +21/2 + +22/2 + +23/2 + +24/2 + +25/2 + +26/2 + +27/2 + +28/2 + +29/2 + +30/2 + +31/2 + +32/2 + +33/2 + +34/2 + +35/2 + +36/2 + +37/2 + +463 13 December 2012 + +The Package Directories A.16 + + Ada Reference Manual — 2012 Edition + +38/2 + +39/2 + +40/2 + +41/2 + +42/2 + +43/2 + +44/3 + +45/2 + +46/2 + +47/2 + +48/2 + +49/2 + + function Simple_Name (Directory_Entry : in Directory_Entry_Type) + return String; + function Full_Name (Directory_Entry : in Directory_Entry_Type) + return String; + function Kind (Directory_Entry : in Directory_Entry_Type) + return File_Kind; + function Size (Directory_Entry : in Directory_Entry_Type) + return File_Size; + function Modification_Time (Directory_Entry : in Directory_Entry_Type) + return Ada.Calendar.Time; + Status_Error : exception renames Ada.IO_Exceptions.Status_Error; + Name_Error : exception renames Ada.IO_Exceptions.Name_Error; + Use_Error : exception renames Ada.IO_Exceptions.Use_Error; + Device_Error : exception renames Ada.IO_Exceptions.Device_Error; +private + ... -- not specified by the language +end Ada.Directories; + +External files may be classified as directories, special files, or ordinary files. A directory is an external file +that is a container for files on the target system. A special file is an external file that cannot be created or +read by a predefined Ada input-output package. External files that are not special files or directories are +called ordinary files. + +A file name is a string identifying an external file. Similarly, a directory name is a string identifying a +directory. The interpretation of file names and directory names is implementation-defined. + +The full name of an external file is a full specification of the name of the file. If the external environment +allows alternative specifications of the name (for example, abbreviations), the full name should not use +such alternatives. A full name typically will include the names of all of the directories that contain the +item. The simple name of an external file is the name of the item, not including any containing directory +names. Unless otherwise specified, a file name or directory name parameter in a call to a predefined Ada +input-output subprogram can be a full name, a simple name, or any other form of name supported by the +implementation. + +The default directory is the directory that is used if a directory or file name is not a full name (that is, +when the name does not fully identify all of the containing directories). + +A directory entry is a single item in a directory, identifying a single external file (including directories and +special files). + +50/2 + +For each function that returns a string, the lower bound of the returned value is 1. + +51/2 + +52/2 + +53/2 + +54/2 + +55/2 + +The following file and directory operations are provided: + +function Current_Directory return String; + +Returns the full directory name for the current default directory. The name returned shall be +suitable for a future call to Set_Directory. The exception Use_Error is propagated if a default +directory is not supported by the external environment. + +procedure Set_Directory (Directory : in String); + +Sets the current default directory. The exception Name_Error is propagated if the string given as +Directory does not identify an existing directory. The exception Use_Error is propagated if the +external environment does not support making Directory (in the absence of Name_Error) a +default directory. + +A.16 The Package Directories + +13 December 2012 464 + + Ada Reference Manual — 2012 Edition + +procedure Create_Directory (New_Directory : in String; + Form : in String := ""); + +Creates a directory with name New_Directory. The Form parameter can be used to give system- +dependent characteristics of the directory; the interpretation of the Form parameter is +implementation-defined. A null string for Form specifies the use of the default options of the +implementation of the new directory. The exception Name_Error is propagated if the string +given as New_Directory does not allow the identification of a directory. The exception +Use_Error is propagated if the external environment does not support the creation of a directory +with the given name (in the absence of Name_Error) and form. + +procedure Delete_Directory (Directory : in String); + +Deletes an existing empty directory with name Directory. The exception Name_Error is +propagated if the string given as Directory does not identify an existing directory. The exception +Use_Error is propagated if the directory is not empty or the external environment does not +support the deletion of the directory with the given name (in the absence of Name_Error). + +procedure Create_Path (New_Directory : in String; + Form : in String := ""); + +Creates zero or more directories with name New_Directory. Each nonexistent directory named +by New_Directory is created. For example, on a typical Unix system, Create_Path +("/usr/me/my"); would create directory "me" in directory "usr", then create directory "my" in +directory "me". The Form parameter can be used to give system-dependent characteristics of the +directory; the interpretation of the Form parameter is implementation-defined. A null string for +Form specifies the use of the default options of the implementation of the new directory. The +exception Name_Error is propagated if the string given as New_Directory does not allow the +identification of any directory. The exception Use_Error is propagated if the external +environment does not support the creation of any directories with the given name (in the absence +of Name_Error) and form. If Use_Error is propagated, it is unspecified whether a portion of the +directory path is created. + +procedure Delete_Tree (Directory : in String); + +Deletes an existing directory with name Directory. The directory and all of its contents (possibly +including other directories) are deleted. The exception Name_Error is propagated if the string +given as Directory does not identify an existing directory. The exception Use_Error is +propagated if the external environment does not support the deletion of the directory or some +portion of its contents with the given name (in the absence of Name_Error). If Use_Error is +propagated, it is unspecified whether a portion of the contents of the directory is deleted. + +procedure Delete_File (Name : in String); + +Deletes an existing ordinary or special file with name Name. The exception Name_Error is +propagated if the string given as Name does not identify an existing ordinary or special external +file. The exception Use_Error is propagated if the external environment does not support the +deletion of the file with the given name (in the absence of Name_Error). + +procedure Rename (Old_Name, New_Name : in String); + +Renames an existing external file (including directories) with name Old_Name to New_Name. +The exception Name_Error is propagated if the string given as Old_Name does not identify an +existing external file or if the string given as New_Name does not allow the identification of an +external file. The exception Use_Error is propagated if the external environment does not + +56/2 + +57/2 + +58/2 + +59/3 + +60/2 + +61/3 + +62/2 + +63/2 + +64/2 + +65/2 + +66/2 + +67/3 + +465 13 December 2012 + +The Package Directories A.16 + + Ada Reference Manual — 2012 Edition + +68/3 + +69/3 + +70/2 + +71/2 + +72/2 + +73/2 + +74/2 + +75/2 + +76/2 + +77/2 + +78/2 + +79/2 + +80/2 + +support the renaming of the file with the given name (in the absence of Name_Error). In +particular, Use_Error is propagated if a file or directory already exists with name New_Name. + +procedure Copy_File (Source_Name, + Target_Name : in String; + Form : in String := ""); + +Copies the contents of the existing external file with name Source_Name to an external file with +name Target_Name. The resulting external file is a duplicate of the source external file. The +Form parameter can be used to give system-dependent characteristics of the resulting external +file; the interpretation of the Form parameter is implementation-defined. Exception Name_Error +is propagated if the string given as Source_Name does not identify an existing external ordinary +or special file, or if the string given as Target_Name does not allow the identification of an +external file. The exception Use_Error is propagated if the external environment does not +support creating the file with the name given by Target_Name and form given by Form, or +copying of the file with the name given by Source_Name (in the absence of Name_Error). If +Use_Error is propagated, it is unspecified whether a portion of the file is copied. + +The following file and directory name operations are provided: + +function Full_Name (Name : in String) return String; + +Returns the full name corresponding to the file name specified by Name. The exception +Name_Error is propagated if the string given as Name does not allow the identification of an +external file (including directories and special files). + +function Simple_Name (Name : in String) return String; + +Returns the simple name portion of the file name specified by Name. The exception Name_Error +is propagated if the string given as Name does not allow the identification of an external file +(including directories and special files). + +function Containing_Directory (Name : in String) return String; + +Returns the name of the containing directory of the external file (including directories) identified +by Name. (If more than one directory can contain Name, the directory name returned is +implementation-defined.) The exception Name_Error is propagated if the string given as Name +does not allow the identification of an external file. The exception Use_Error is propagated if the +external file does not have a containing directory. + +function Extension (Name : in String) return String; + +Returns the extension name corresponding to Name. The extension name is a portion of a simple +name (not including any separator characters), typically used to identify the file class. If the +external environment does not have extension names, then the null string is returned. The +exception Name_Error is propagated if the string given as Name does not allow the +identification of an external file. + +function Base_Name (Name : in String) return String; + +Returns the base name corresponding to Name. The base name is the remainder of a simple +name after removing any extension and extension separators. The exception Name_Error is +propagated if the string given as Name does not allow the identification of an external file +(including directories and special files). + +A.16 The Package Directories + +13 December 2012 466 + + Ada Reference Manual — 2012 Edition + +function Compose (Containing_Directory : in String := ""; + Name : in String; + Extension : in String := "") return String; + +Returns the name of the external file with the specified Containing_Directory, Name, and +Extension. If Extension is the null string, then Name is interpreted as a simple name; otherwise, +Name is interpreted as a base name. The exception Name_Error is propagated if the string given +as Containing_Directory is not null and does not allow the identification of a directory, or if the +string given as Extension is not null and is not a possible extension, or if the string given as +Name is not a possible simple name (if Extension is null) or base name (if Extension is nonnull). + +function Name_Case_Equivalence (Name : in String) return Name_Case_Kind; + +Returns the file name equivalence rule for the directory containing Name. Raises Name_Error if +Name is not a full name. Returns Case_Sensitive if file names that differ only in the case of +letters are considered different names. If file names that differ only in the case of letters are +considered the same name, then Case_Preserving is returned if names have the case of the file +name used when a file is created; and Case_Insensitive is returned otherwise. Returns Unknown +if the file name equivalence is not known. + +The following file and directory queries and types are provided: + +type File_Kind is (Directory, Ordinary_File, Special_File); + +The type File_Kind represents the kind of file represented by an external file or directory. + +type File_Size is range 0 .. implementation-defined; + +The type File_Size represents the size of an external file. + +function Exists (Name : in String) return Boolean; + +Returns True if an external file represented by Name exists, and False otherwise. The exception +Name_Error is propagated if the string given as Name does not allow the identification of an +external file (including directories and special files). + +function Kind (Name : in String) return File_Kind; + +Returns the kind of external file represented by Name. The exception Name_Error is propagated +if the string given as Name does not allow the identification of an existing external file. + +function Size (Name : in String) return File_Size; + +Returns the size of the external file represented by Name. The size of an external file is the +number of stream elements contained in the file. If the external file is not an ordinary file, the +result is implementation-defined. The exception Name_Error is propagated if the string given as +Name does not allow the identification of an existing external file. The exception +Constraint_Error is propagated if the file size is not a value of type File_Size. + +function Modification_Time (Name : in String) return Ada.Calendar.Time; + +Returns the time that the external file represented by Name was most recently modified. If the +external file is not an ordinary file, the result is implementation-defined. The exception +Name_Error is propagated if the string given as Name does not allow the identification of an +existing external file. The exception Use_Error is propagated if the external environment does +not support reading the modification time of the file with the name given by Name (in the +absence of Name_Error). + +The following directory searching operations and types are provided: + +81/2 + +82/3 + +82.1/3 + +82.2/3 + +83/2 + +84/2 + +85/2 + +86/2 + +87/2 + +88/2 + +89/2 + +90/2 + +91/2 + +92/2 + +93/2 + +94/2 + +95/2 + +96/2 + +467 13 December 2012 + +The Package Directories A.16 + + Ada Reference Manual — 2012 Edition + +97/2 + +98/2 + +99/2 + +100/2 + +101/2 + +102/2 + +103/2 + +104/3 + +105/2 + +106/2 + +107/2 + +108/2 + +109/2 + +110/3 + +type Directory_Entry_Type is limited private; + +The type Directory_Entry_Type represents a single item in a directory. These items can only be +created by the Get_Next_Entry procedure in this package. Information about the item can be +obtained from the functions declared in this package. A default-initialized object of this type is +invalid; objects returned from Get_Next_Entry are valid. + +type Filter_Type is array (File_Kind) of Boolean; + +The type Filter_Type specifies which directory entries are provided from a search operation. If +the Directory component is True, directory entries representing directories are provided. If the +Ordinary_File component is True, directory entries representing ordinary files are provided. If +the Special_File component is True, directory entries representing special files are provided. + +type Search_Type is limited private; + +The type Search_Type contains the state of a directory search. A default-initialized Search_Type +object has no entries available (function More_Entries returns False). Type Search_Type needs +finalization (see 7.6). + +procedure Start_Search (Search : in out Search_Type; + Directory : in String; + Pattern : in String; + Filter : in Filter_Type := (others => True)); + +Starts a search in the directory named by Directory for entries matching Pattern and Filter. +Pattern represents a pattern for matching file names. If Pattern is the null string, all items in the +directory are matched; otherwise, the interpretation of Pattern is implementation-defined. Only +items that match Filter will be returned. After a successful call on Start_Search, the object +Search may have entries available, but it may have no entries available if no files or directories +match Pattern and Filter. The exception Name_Error is propagated if the string given by +Directory does not identify an existing directory, or if Pattern does not allow the identification of +any possible external file or directory. The exception Use_Error is propagated if the external +environment does not support the searching of the directory with the given name (in the absence +of Name_Error). When Start_Search propagates Name_Error or Use_Error, the object Search +will have no entries available. + +procedure End_Search (Search : in out Search_Type); + +Ends the search represented by Search. After a successful call on End_Search, the object Search +will have no entries available. + +function More_Entries (Search : in Search_Type) return Boolean; + +Returns True if more entries are available to be returned by a call to Get_Next_Entry for the +specified search object, and False otherwise. + +procedure Get_Next_Entry (Search : in out Search_Type; + Directory_Entry : out Directory_Entry_Type); + +Returns the next Directory_Entry for the search described by Search that matches the pattern and +filter. If no further matches are available, Status_Error is raised. It is implementation-defined as +to whether the results returned by this subprogram are altered if the contents of the directory are +altered while the Search object is valid (for example, by another program). The exception +Use_Error is propagated if the external environment does not support continued searching of the +directory represented by Search. + +A.16 The Package Directories + +13 December 2012 468 + + Ada Reference Manual — 2012 Edition + +procedure Search ( + Directory : in String; + Pattern : in String; + Filter : in Filter_Type := (others => True); + Process : not null access procedure ( + Directory_Entry : in Directory_Entry_Type)); + +Searches in the directory named by Directory for entries matching Pattern and Filter. The +subprogram designated by Process is called with each matching entry in turn. Pattern represents +a pattern for matching file names. If Pattern is the null string, all items in the directory are +matched; otherwise, the interpretation of Pattern is implementation-defined. Only items that +match Filter will be returned. The exception Name_Error is propagated if the string given by +Directory does not identify an existing directory, or if Pattern does not allow the identification of +any possible external file or directory. The exception Use_Error is propagated if the external +environment does not support the searching of the directory with the given name (in the absence +of Name_Error). + +function Simple_Name (Directory_Entry : in Directory_Entry_Type) + return String; + +Returns the simple external name of the external file (including directories) represented by +Directory_Entry. The format of the name returned is implementation-defined. The exception +Status_Error is propagated if Directory_Entry is invalid. + +function Full_Name (Directory_Entry : in Directory_Entry_Type) + return String; + +Returns the full external name of the external file (including directories) represented by +Directory_Entry. The format of the name returned is implementation-defined. The exception +Status_Error is propagated if Directory_Entry is invalid. + +function Kind (Directory_Entry : in Directory_Entry_Type) + return File_Kind; + +Returns the kind of external file represented by Directory_Entry. The exception Status_Error is +propagated if Directory_Entry is invalid. + +function Size (Directory_Entry : in Directory_Entry_Type) + return File_Size; + +Returns the size of the external file represented by Directory_Entry. The size of an external file +is the number of stream elements contained in the file. If the external file represented by +Directory_Entry is not an ordinary file, the result is implementation-defined. The exception +Status_Error is propagated if Directory_Entry is invalid. The exception Constraint_Error is +propagated if the file size is not a value of type File_Size. + +function Modification_Time (Directory_Entry : in Directory_Entry_Type) + return Ada.Calendar.Time; + +Returns the time that the external file represented by Directory_Entry was most recently +modified. If the external file represented by Directory_Entry is not an ordinary file, the result is +implementation-defined. The exception Status_Error is propagated if Directory_Entry is invalid. +The exception Use_Error is propagated if the external environment does not support reading the +modification time of the file represented by Directory_Entry. + +111/2 + +112/3 + +113/2 + +114/2 + +115/2 + +116/2 + +117/2 + +118/2 + +119/2 + +120/2 + +121/2 + +122/2 + +469 13 December 2012 + +The Package Directories A.16 + + Ada Reference Manual — 2012 Edition + +123/2 + +For Copy_File, if Source_Name identifies an existing external ordinary file created by a predefined Ada +input-output package, and Target_Name and Form can be used in the Create operation of that input-output +package with mode Out_File without raising an exception, then Copy_File shall not propagate Use_Error. + +Implementation Requirements + +124/2 + +125/3 + +126/2 + +127/2 + +128/2 + +129/2 + +130/2 + +131/2 + +Implementation Advice + +If other information about a file (such as the owner or creation date) is available in a directory entry, the +implementation should provide functions in a child package Directories.Information to retrieve it. + +Start_Search and Search should raise Name_Error if Pattern is malformed, but not if it could represent a +file in the directory but does not actually do so. + +Rename should be supported at least when both New_Name and Old_Name are simple names and +New_Name does not identify an existing external file. + +NOTES +41 The operations Containing_Directory, Full_Name, Simple_Name, Base_Name, Extension, and Compose operate on +file names, not external files. The files identified by these operations do not need to exist. Name_Error is raised only if the +file name is malformed and cannot possibly identify a file. Of these operations, only the result of Full_Name depends on +the current default directory; the result of the others depends only on their parameters. + +42 Using access types, values of Search_Type and Directory_Entry_Type can be saved and queried later. However, +another task or application can modify or delete the file represented by a Directory_Entry_Type value or the directory +represented by a Search_Type value; such a value can only give the information valid at the time it is created. Therefore, +long-term storage of these values is not recommended. + +43 If the target system does not support directories inside of directories, then Kind will never return Directory and +Containing_Directory will always raise Use_Error. + +44 If the target system does not support creation or deletion of directories, then Create_Directory, Create_Path, +Delete_Directory, and Delete_Tree will always propagate Use_Error. + +45 To move a file or directory to a different location, use Rename. Most target systems will allow renaming of files from +one directory to another. If the target file or directory might already exist, it should be deleted first. + +A.16.1 The Package Directories.Hierarchical_File_Names + +1/3 + +The library package Directories.Hierarchical_File_Names is an optional package providing operations for +file name construction and decomposition for targets with hierarchical file naming. + +Static Semantics + +2/3 + +3/3 + +4/3 + +5/3 + +6/3 + +7/3 + +8/3 + +9/3 + +10/3 + +11/3 + +12/3 + +If provided, the library package Directories.Hierarchical_File_Names has the following declaration: + +package Ada.Directories.Hierarchical_File_Names is + function Is_Simple_Name (Name : in String) return Boolean; + function Is_Root_Directory_Name (Name : in String) return Boolean; + function Is_Parent_Directory_Name (Name : in String) return Boolean; + function Is_Current_Directory_Name (Name : in String) return Boolean; + function Is_Full_Name (Name : in String) return Boolean; + function Is_Relative_Name (Name : in String) return Boolean; + function Simple_Name (Name : in String) return String + renames Ada.Directories.Simple_Name; + function Containing_Directory (Name : in String) return String + renames Ada.Directories.Containing_Directory; + function Initial_Directory (Name : in String) return String; + +A.16 The Package Directories + +13 December 2012 470 + + Ada Reference Manual — 2012 Edition + + function Relative_Name (Name : in String) return String; + function Compose (Directory : in String := ""; + Relative_Name : in String; + Extension : in String := "") return String; +end Ada.Directories.Hierarchical_File_Names; + +In addition to the operations provided in package Directories.Hierarchical_File_Names, the operations in +package Directories can be used with hierarchical file names. In particular, functions Full_Name, +Base_Name, and Extension provide additional capabilities for hierarchical file names. + +function Is_Simple_Name (Name : in String) return Boolean; + +Returns True if Name is a simple name, and returns False otherwise. + +function Is_Root_Directory_Name (Name : in String) return Boolean; + +Returns True if Name is syntactically a root (a directory that cannot be decomposed further), and +returns False otherwise. + +function Is_Parent_Directory_Name (Name : in String) return Boolean; + +Returns True if Name can be used to indicate symbolically the parent directory of any directory, +and returns False otherwise. + +function Is_Current_Directory_Name (Name : in String) return Boolean; + +Returns True if Name can be used to indicate symbolically the directory itself for any directory, +and returns False otherwise. + +function Is_Full_Name (Name : in String) return Boolean; + +Returns True if the leftmost directory part of Name is a root, and returns False otherwise. + +function Is_Relative_Name (Name : in String) return Boolean; + +Returns True if Name allows the identification of an external file (including directories and +special files) but is not a full name, and returns False otherwise. + +function Initial_Directory (Name : in String) return String; + +Returns the leftmost directory part in Name. That is, it returns a root directory name (for a full +name), or one of a parent directory name, a current directory name, or a simple name (for a +relative name). The exception Name_Error is propagated if the string given as Name does not +allow the identification of an external file (including directories and special files). + +function Relative_Name (Name : in String) return String; + +Returns the entire file name except the Initial_Directory portion. The exception Name_Error is +propagated if the string given as Name does not allow the identification of an external file +(including directories and special files), or if Name has a single part (this includes if any of +Is_Simple_Name, +or +Is_Current_Directory_Name are True). + +Is_Parent_Directory_Name, + +Is_Root_Directory_Name, + +function Compose (Directory : in String := ""; + Relative_Name : in String; + Extension : in String := "") return String; + +Returns the name of the external file with the specified Directory, Relative_Name, and +Extension. The exception Name_Error is propagated if the string given as Directory is not the +null string and does not allow the identification of a directory, or if Is_Relative_Name +(Relative_Name) is False, or if the string given as Extension is not the null string and is not a +possible extension, or if Extension is not the null string and Simple_Name (Relative_Name) is +not a base name. + +471 13 December 2012 + +The Package Directories.Hierarchical_File_Names A.16.1 + +13/3 + +14/3 + +15/3 + +16/3 + +17/3 + +18/3 + +19/3 + +20/3 + +21/3 + +22/3 + +23/3 + +24/3 + +25/3 + +26/3 + +27/3 + +28/3 + +29/3 + +30/3 + +31/3 + +32/3 + +33/3 + +34/3 + + Ada Reference Manual — 2012 Edition + +35/3 + +The result of Compose is a full name if Is_Full_Name (Directory) is True; result is a relative +name otherwise. + +36/3 + +Directories.Hierarchical_File_Names should be provided for systems with hierarchical file naming, and +should not be provided on other systems. + +Implementation Advice + +37/3 + +38/3 + +1/2 + +2/2 + +3/2 + +4/2 + +4.1/3 + +5/2 + +6/2 + +7/2 + +8/3 + +9/2 + +10/2 + +11/2 + +11.1/3 + +11.2/3 + +12/2 + +13/3 + +NOTES +46 These operations operate on file names, not external files. The files identified by these operations do not need to exist. +Name_Error is raised only as specified or if the file name is malformed and cannot possibly identify a file. The result of +these operations depends only on their parameters. + +47 Containing_Directory raises Use_Error if Name does not have a containing directory, including when any of +Is_Simple_Name, Is_Root_Directory_Name, Is_Parent_Directory_Name, or Is_Current_Directory_Name are True. + +A.17 The Package Environment_Variables + +The package Environment_Variables allows a program to read or modify environment variables. +Environment variables are name-value pairs, where both the name and value are strings. The definition of +what constitutes an environment variable, and the meaning of the name and value, are implementation +defined. + +The library package Environment_Variables has the following declaration: + +Static Semantics + +package Ada.Environment_Variables is + pragma Preelaborate(Environment_Variables); + function Value (Name : in String) return String; + function Value (Name : in String; Default : in String) return String; + function Exists (Name : in String) return Boolean; + procedure Set (Name : in String; Value : in String); + procedure Clear (Name : in String); + procedure Clear; + procedure Iterate + (Process : not null access procedure (Name, Value : in String)); +end Ada.Environment_Variables; + +function Value (Name : in String) return String; + +If the external execution environment supports environment variables, then Value returns the +value of the environment variable with the given name. If no environment variable with the +given name exists, then Constraint_Error is propagated. If the execution environment does not +support environment variables, then Program_Error is propagated. + +function Value (Name : in String; Default : in String) return String; + +If the external execution environment supports environment variables and an environment +variable with the given name currently exists, then Value returns its value; otherwise, it returns +Default. + +function Exists (Name : in String) return Boolean; + +If the external execution environment supports environment variables and an environment +variable with the given name currently exists, then Exists returns True; otherwise, it returns +False. + +A.16.1 The Package Directories.Hierarchical_File_Names + +13 December 2012 472 + + Ada Reference Manual — 2012 Edition + +procedure Set (Name : in String; Value : in String); + +If the external execution environment supports environment variables, then Set first clears any +existing environment variable with the given name, and then defines a single new environment +variable with the given name and value. Otherwise, Program_Error is propagated. + +If implementation-defined circumstances prohibit the definition of an environment variable with +the given name and value, then Constraint_Error is propagated. + +It is implementation defined whether there exist values for which the call Set(Name, Value) has +the same effect as Clear (Name). + +procedure Clear (Name : in String); + +If the external execution environment supports environment variables, then Clear deletes all +existing environment variables with the given name. Otherwise, Program_Error is propagated. + +procedure Clear; + +If the external execution environment supports environment variables, then Clear deletes all +existing environment variables. Otherwise, Program_Error is propagated. + +procedure Iterate + (Process : not null access procedure (Name, Value : in String)); + +If the external execution environment supports environment variables, then Iterate calls the +subprogram designated by Process for each existing environment variable, passing the name and +value of that environment variable. Otherwise, Program_Error is propagated. + +14/2 + +15/3 + +16/2 + +17/2 + +18/2 + +19/3 + +20/2 + +21/3 + +22/3 + +23/3 + +If several environment variables exist that have the same name, Process is called once for each +such variable. + +24/2 + +Bounded (Run-Time) Errors + +It is a bounded error to call Value if more than one environment variable exists with the given name; the +possible outcomes are that: + +• one of the values is returned, and that same value is returned in subsequent calls in the absence + +of changes to the environment; or + +• Program_Error is propagated. + +Erroneous Execution + +Making calls to the procedures Set or Clear concurrently with calls to any subprogram of package +Environment_Variables, or to any instantiation of Iterate, results in erroneous execution. + +Making calls to the procedures Set or Clear in the actual subprogram corresponding to the Process +parameter of Iterate results in erroneous execution. + +25/2 + +26/2 + +27/2 + +28/2 + +29/2 + +An implementation shall document how the operations of this package behave if environment variables are +changed by external mechanisms (for instance, calling operating system services). + +30/2 + +Documentation Requirements + +An implementation running on a system that does not support environment variables is permitted to define +the operations of package Environment_Variables with the semantics corresponding to the case where the + +31/2 + +Implementation Permissions + +473 13 December 2012 + +The Package Environment_Variables A.17 + + Ada Reference Manual — 2012 Edition + +external execution environment does support environment variables. In this case, it shall provide a +mechanism to initialize a nonempty set of environment variables prior to the execution of a partition. + +Implementation Advice + +32/2 + +33/2 + +If the execution environment supports subprocesses, the currently defined environment variables should be +used to initialize the environment variables of a subprocess. + +Changes to the environment variables made outside the control of this package should be reflected +immediately in the effect of the operations of this package. Changes to the environment variables made +using this package should be reflected immediately in the external execution environment. This package +should not perform any buffering of the environment variables. + +A.17 The Package Environment_Variables + +13 December 2012 474 + + Ada Reference Manual — 2012 Edition + +A.18 Containers + +This clause presents the specifications of the package Containers and several child packages, which +provide facilities for storing collections of elements. + +A variety of sequence and associative containers are provided. Each container includes a cursor type. A +cursor is a reference to an element within a container. Many operations on cursors are common to all of +the containers. A cursor referencing an element in a container is considered to be overlapping with the +container object itself. + +Within this clause we provide Implementation Advice for the desired average or worst case time +complexity of certain operations on a container. This advice is expressed using the Landau symbol O(X). +Presuming f is some function of a length parameter N and t(N) is the time the operation takes (on average +or worst case, as specified) for the length N, a complexity of O(f(N)) means that there exists a finite A +such that for any N, t(N)/f(N) < A. + +If the advice suggests that the complexity should be less than O(f(N)), then for any arbitrarily small +positive real D, there should exist a positive integer M such that for all N > M, t(N)/f(N) < D. + +When a formal function is used to provide an ordering for a container, it is generally required to define a +strict weak ordering. A function "<" defines a strict weak ordering if it is irreflexive, asymmetric, +transitive, and in addition, if x < y for any values x and y, then for all other values z, (x < z) or (z < y). + +A.18.1 The Package Containers + +The package Containers is the root of the containers subsystem. + +The library package Containers has the following declaration: + +Static Semantics + +package Ada.Containers is + pragma Pure(Containers); + type Hash_Type is mod implementation-defined; + type Count_Type is range 0 .. implementation-defined; + Capacity_Error : exception; +end Ada.Containers; + +Hash_Type represents the range of the result of a hash function. Count_Type represents the (potential or +actual) number of elements of a container. + +Capacity_Error is raised when the capacity of a container is exceeded. + +Hash_Type'Modulus should be at least 2**32. Count_Type'Last should be at least 2**31–1. + +Implementation Advice + +A.18.2 The Generic Package Containers.Vectors + +The language-defined generic package Containers.Vectors provides private types Vector and Cursor, and a +set of operations for each type. A vector container allows insertion and deletion at any position, but it is +specifically optimized for insertion and deletion at the high end (the end with the higher index) of the +container. A vector container also provides random access to its elements. + +475 13 December 2012 + +Containers A.18 + +1/2 + +2/2 + +3/2 + +4/2 + +5/3 + +1/2 + +2/2 + +3/2 + +4/2 + +5/2 + +5.1/3 + +6/2 + +7/2 + +7.1/3 + +8/2 + +1/2 + + Ada Reference Manual — 2012 Edition + +2/2 + +3/2 + +A vector container behaves conceptually as an array that expands as necessary as items are inserted. The +length of a vector is the number of elements that the vector contains. The capacity of a vector is the +maximum number of elements that can be inserted into the vector prior to it being automatically expanded. + +Elements in a vector container can be referred to by an index value of a generic formal type. The first +element of a vector always has its index value equal to the lower bound of the formal type. + +4/2 + +A vector container may contain empty elements. Empty elements do not have a specified value. + +5/2 + +6/3 + +7/2 + +8/3 + +9/2 + +10/2 + +11/2 + +11.1/3 + +11.2/3 + +12/2 + +13/2 + +14/2 + +15/2 + +16/2 + +17/2 + +18/2 + +19/2 + +20/2 + +21/2 + +22/2 + +The generic library package Containers.Vectors has the following declaration: + +Static Semantics + +with Ada.Iterator_Interfaces; +generic + type Index_Type is range <>; + type Element_Type is private; + with function "=" (Left, Right : Element_Type) + return Boolean is <>; +package Ada.Containers.Vectors is + pragma Preelaborate(Vectors); + pragma Remote_Types(Vectors); + subtype Extended_Index is + Index_Type'Base range + Index_Type'First-1 .. + Index_Type'Min (Index_Type'Base'Last - 1, Index_Type'Last) + 1; + No_Index : constant Extended_Index := Extended_Index'First; + type Vector is tagged private + with Constant_Indexing => Constant_Reference, + Variable_Indexing => Reference, + Default_Iterator => Iterate, + Iterator_Element => Element_Type; + pragma Preelaborable_Initialization(Vector); + type Cursor is private; + pragma Preelaborable_Initialization(Cursor); + Empty_Vector : constant Vector; + No_Element : constant Cursor; + function Has_Element (Position : Cursor) return Boolean; + package Vector_Iterator_Interfaces is new + Ada.Iterator_Interfaces (Cursor, Has_Element); + function "=" (Left, Right : Vector) return Boolean; + function To_Vector (Length : Count_Type) return Vector; + function To_Vector + (New_Item : Element_Type; + Length : Count_Type) return Vector; + function "&" (Left, Right : Vector) return Vector; + function "&" (Left : Vector; + Right : Element_Type) return Vector; + function "&" (Left : Element_Type; + Right : Vector) return Vector; + function "&" (Left, Right : Element_Type) return Vector; + function Capacity (Container : Vector) return Count_Type; + procedure Reserve_Capacity (Container : in out Vector; + Capacity : in Count_Type); + function Length (Container : Vector) return Count_Type; + procedure Set_Length (Container : in out Vector; + Length : in Count_Type); + +A.18.2 The Generic Package Containers.Vectors + +13 December 2012 476 + + Ada Reference Manual — 2012 Edition + + function Is_Empty (Container : Vector) return Boolean; + procedure Clear (Container : in out Vector); + function To_Cursor (Container : Vector; + Index : Extended_Index) return Cursor; + function To_Index (Position : Cursor) return Extended_Index; + function Element (Container : Vector; + Index : Index_Type) + return Element_Type; + function Element (Position : Cursor) return Element_Type; + procedure Replace_Element (Container : in out Vector; + Index : in Index_Type; + New_Item : in Element_Type); + procedure Replace_Element (Container : in out Vector; + Position : in Cursor; + New_item : in Element_Type); + procedure Query_Element + (Container : in Vector; + Index : in Index_Type; + Process : not null access procedure (Element : in Element_Type)); + procedure Query_Element + (Position : in Cursor; + Process : not null access procedure (Element : in Element_Type)); + procedure Update_Element + (Container : in out Vector; + Index : in Index_Type; + Process : not null access procedure + (Element : in out Element_Type)); + procedure Update_Element + (Container : in out Vector; + Position : in Cursor; + Process : not null access procedure + (Element : in out Element_Type)); + type Constant_Reference_Type + (Element : not null access constant Element_Type) is private + with Implicit_Dereference => Element; + type Reference_Type (Element : not null access Element_Type) is private + with Implicit_Dereference => Element; + function Constant_Reference (Container : aliased in Vector; + Index : in Index_Type) + return Constant_Reference_Type; + function Reference (Container : aliased in out Vector; + Index : in Index_Type) + return Reference_Type; + function Constant_Reference (Container : aliased in Vector; + Position : in Cursor) + return Constant_Reference_Type; + function Reference (Container : aliased in out Vector; + Position : in Cursor) + return Reference_Type; + procedure Assign (Target : in out Vector; Source : in Vector); + function Copy (Source : Vector; Capacity : Count_Type := 0) + return Vector; + procedure Move (Target : in out Vector; + Source : in out Vector); + procedure Insert (Container : in out Vector; + Before : in Extended_Index; + New_Item : in Vector); + +23/2 + +24/2 + +25/2 + +26/2 + +27/2 + +28/2 + +29/2 + +30/2 + +31/2 + +32/2 + +33/2 + +34/2 + +34.1/3 + +34.2/3 + +34.3/3 + +34.4/3 + +34.5/3 + +34.6/3 + +34.7/3 + +34.8/3 + +35/2 + +36/2 + +477 13 December 2012 + +The Generic Package Containers.Vectors A.18.2 + + Ada Reference Manual — 2012 Edition + +37/2 + +38/2 + +39/2 + +40/2 + +41/2 + +42/2 + +43/2 + +44/2 + +45/2 + +46/2 + +47/2 + +48/2 + +49/2 + +50/2 + +51/2 + +52/2 + +53/2 + +54/2 + +55/2 + + procedure Insert (Container : in out Vector; + Before : in Cursor; + New_Item : in Vector); + procedure Insert (Container : in out Vector; + Before : in Cursor; + New_Item : in Vector; + Position : out Cursor); + procedure Insert (Container : in out Vector; + Before : in Extended_Index; + New_Item : in Element_Type; + Count : in Count_Type := 1); + procedure Insert (Container : in out Vector; + Before : in Cursor; + New_Item : in Element_Type; + Count : in Count_Type := 1); + procedure Insert (Container : in out Vector; + Before : in Cursor; + New_Item : in Element_Type; + Position : out Cursor; + Count : in Count_Type := 1); + procedure Insert (Container : in out Vector; + Before : in Extended_Index; + Count : in Count_Type := 1); + procedure Insert (Container : in out Vector; + Before : in Cursor; + Position : out Cursor; + Count : in Count_Type := 1); + procedure Prepend (Container : in out Vector; + New_Item : in Vector); + procedure Prepend (Container : in out Vector; + New_Item : in Element_Type; + Count : in Count_Type := 1); + procedure Append (Container : in out Vector; + New_Item : in Vector); + procedure Append (Container : in out Vector; + New_Item : in Element_Type; + Count : in Count_Type := 1); + procedure Insert_Space (Container : in out Vector; + Before : in Extended_Index; + Count : in Count_Type := 1); + procedure Insert_Space (Container : in out Vector; + Before : in Cursor; + Position : out Cursor; + Count : in Count_Type := 1); + procedure Delete (Container : in out Vector; + Index : in Extended_Index; + Count : in Count_Type := 1); + procedure Delete (Container : in out Vector; + Position : in out Cursor; + Count : in Count_Type := 1); + procedure Delete_First (Container : in out Vector; + Count : in Count_Type := 1); + procedure Delete_Last (Container : in out Vector; + Count : in Count_Type := 1); + procedure Reverse_Elements (Container : in out Vector); + procedure Swap (Container : in out Vector; + I, J : in Index_Type); + +A.18.2 The Generic Package Containers.Vectors + +13 December 2012 478 + + Ada Reference Manual — 2012 Edition + + procedure Swap (Container : in out Vector; + I, J : in Cursor); + function First_Index (Container : Vector) return Index_Type; + function First (Container : Vector) return Cursor; + function First_Element (Container : Vector) + return Element_Type; + function Last_Index (Container : Vector) return Extended_Index; + function Last (Container : Vector) return Cursor; + function Last_Element (Container : Vector) + return Element_Type; + function Next (Position : Cursor) return Cursor; + procedure Next (Position : in out Cursor); + function Previous (Position : Cursor) return Cursor; + procedure Previous (Position : in out Cursor); + function Find_Index (Container : Vector; + Item : Element_Type; + Index : Index_Type := Index_Type'First) + return Extended_Index; + function Find (Container : Vector; + Item : Element_Type; + Position : Cursor := No_Element) + return Cursor; + function Reverse_Find_Index (Container : Vector; + Item : Element_Type; + Index : Index_Type := Index_Type'Last) + return Extended_Index; + function Reverse_Find (Container : Vector; + Item : Element_Type; + Position : Cursor := No_Element) + return Cursor; + function Contains (Container : Vector; + Item : Element_Type) return Boolean; +This paragraph was deleted. + procedure Iterate + (Container : in Vector; + Process : not null access procedure (Position : in Cursor)); + procedure Reverse_Iterate + (Container : in Vector; + Process : not null access procedure (Position : in Cursor)); + function Iterate (Container : in Vector) + return Vector_Iterator_Interfaces.Reversible_Iterator'Class; + function Iterate (Container : in Vector; Start : in Cursor) + return Vector_Iterator_Interfaces.Reversible_Iterator'Class; + generic + with function "<" (Left, Right : Element_Type) + return Boolean is <>; + package Generic_Sorting is + function Is_Sorted (Container : Vector) return Boolean; + procedure Sort (Container : in out Vector); + procedure Merge (Target : in out Vector; + Source : in out Vector); + end Generic_Sorting; +private + +56/2 + +57/2 + +58/2 + +59/2 + +60/2 + +61/2 + +62/2 + +63/2 + +64/2 + +65/2 + +66/2 + +67/2 + +68/2 + +69/2 + +70/2 + +71/2 + +72/3 + +73/2 + +74/2 + +74.1/3 + +74.2/3 + +75/2 + +76/2 + +77/2 + +78/2 + +79/2 + +80/2 + +479 13 December 2012 + +The Generic Package Containers.Vectors A.18.2 + + 81/2 + +82/2 + +83/2 + +Ada Reference Manual — 2012 Edition + + ... -- not specified by the language +end Ada.Containers.Vectors; + +The actual function for the generic formal function "=" on Element_Type values is expected to define a +reflexive and symmetric relationship and return the same result value each time it is called with a +particular pair of values. If it behaves in some other manner, the functions defined to use it return an +unspecified value. The exact arguments and number of calls of this generic formal function by the +functions defined to use it are unspecified. + +84/2 + +The type Vector is used to represent vectors. The type Vector needs finalization (see 7.6). + +85/2 + +86/2 + +87/2 + +88/2 + +Empty_Vector represents the empty vector object. It has a length of 0. If an object of type Vector is not +otherwise initialized, it is initialized to the same value as Empty_Vector. + +No_Element represents a cursor that designates no element. If an object of type Cursor is not otherwise +initialized, it is initialized to the same value as No_Element. + +The predefined "=" operator for type Cursor returns True if both cursors are No_Element, or designate the +same element in the same container. + +Execution of the default implementation of the Input, Output, Read, or Write attribute of type Cursor +raises Program_Error. + +88.1/3 + +Vector'Write for a Vector object V writes Length(V) elements of the vector to the stream. It also may write +additional information about the vector. + +88.2/3 + +Vector'Read reads the representation of a vector from the stream, and assigns to Item a vector with the +same length and elements as was written by Vector'Write. + +89/2 + +No_Index represents a position that does not correspond to any element. The subtype Extended_Index +includes the indices covered by Index_Type plus the value No_Index and, if it exists, the successor to the +Index_Type'Last. + +89.1/3 + +If an operation attempts to modify the vector such that the position of the last element would be greater +than Index_Type'Last, then the operation propagates Constraint_Error. + +90/2 + +91/2 + +92/2 + +93/2 + +93.1/3 + +94/2 + +95/2 + +96/2 + +Some operations of this generic package have access-to-subprogram parameters. To ensure such +operations are well-defined, they guard against certain actions by the designated subprogram. In particular, +some operations check for “tampering with cursors” of a container because they depend on the set of +elements of the container remaining constant, and others check for “tampering with elements” of a +container because they depend on elements of the container not being replaced. + +A subprogram is said to tamper with cursors of a vector object V if: + +• + +• +• +• + +it inserts or deletes elements of V, that is, it calls the Insert, Insert_Space, Clear, Delete, or +Set_Length procedures with V as a parameter; or + +it finalizes V; or + +it calls the Assign procedure with V as the Target parameter; or + +it calls the Move procedure with V as a parameter. + +A subprogram is said to tamper with elements of a vector object V if: + +• + +it tampers with cursors of V; or + +A.18.2 The Generic Package Containers.Vectors + +13 December 2012 480 + + Ada Reference Manual — 2012 Edition + +• + +it replaces one or more elements of V, that is, it calls the Replace_Element, Reverse_Elements, +or Swap procedures or the Sort or Merge procedures of an instance of Generic_Sorting with V as +a parameter. + +When tampering with cursors is prohibited for a particular vector object V, Program_Error is propagated +by a call of any language-defined subprogram that is defined to tamper with the cursors of V, leaving V +unmodified. Similarly, when tampering with elements is prohibited for a particular vector object V, +Program_Error is propagated by a call of any language-defined subprogram that is defined to tamper with +the elements of V (or tamper with the cursors of V), leaving V unmodified. + +function Has_Element (Position : Cursor) return Boolean; + +Returns True if Position designates an element, and returns False otherwise. + +function "=" (Left, Right : Vector) return Boolean; + +If Left and Right denote the same vector object, then the function returns True. If Left and Right +have different lengths, then the function returns False. Otherwise, it compares each element in +Left to the corresponding element in Right using the generic formal equality operator. If any +such comparison returns False, the function returns False; otherwise, it returns True. Any +exception raised during evaluation of element equality is propagated. + +function To_Vector (Length : Count_Type) return Vector; + +Returns a vector with a length of Length, filled with empty elements. + +function To_Vector + (New_Item : Element_Type; + Length : Count_Type) return Vector; + +97/2 + +97.1/3 + +97.2/3 + +97.3/3 + +98/2 + +99/3 + +100/2 + +101/2 + +102/2 + +Returns a vector with a length of Length, filled with elements initialized to the value New_Item. + +103/2 + +function "&" (Left, Right : Vector) return Vector; + +Returns a vector comprising the elements of Left followed by the elements of Right. + +function "&" (Left : Vector; + Right : Element_Type) return Vector; + +Returns a vector comprising the elements of Left followed by the element Right. + +function "&" (Left : Element_Type; + Right : Vector) return Vector; + +Returns a vector comprising the element Left followed by the elements of Right. + +function "&" (Left, Right : Element_Type) return Vector; + +Returns a vector comprising the element Left followed by the element Right. + +function Capacity (Container : Vector) return Count_Type; + +Returns the capacity of Container. + +procedure Reserve_Capacity (Container : in out Vector; + Capacity : in Count_Type); + +If the capacity of Container is already greater than or equal to Capacity, then Reserve_Capacity +has no effect. Otherwise, Reserve_Capacity allocates additional storage as necessary to ensure +that the length of the resulting vector can become at least the value Capacity without requiring +an additional call to Reserve_Capacity, and is large enough to hold the current length of +Container. Reserve_Capacity then, as necessary, moves elements into the new storage and + +481 13 December 2012 + +The Generic Package Containers.Vectors A.18.2 + +104/2 + +105/2 + +106/2 + +107/2 + +108/2 + +109/2 + +110/2 + +111/2 + +112/2 + +113/2 + +114/2 + +115/3 + + Ada Reference Manual — 2012 Edition + +deallocates any storage no longer needed. Any exception raised during allocation is propagated +and Container is not modified. + +function Length (Container : Vector) return Count_Type; + +Returns the number of elements in Container. + +procedure Set_Length (Container : in out Vector; + Length : in Count_Type); + +If Length is larger than the capacity of Container, Set_Length calls Reserve_Capacity +(Container, Length), then sets the length of the Container to Length. If Length is greater than the +original length of Container, empty elements are added to Container; otherwise, elements are +removed from Container. + +function Is_Empty (Container : Vector) return Boolean; + +Equivalent to Length (Container) = 0. + +procedure Clear (Container : in out Vector); + +Removes all the elements from Container. The capacity of Container does not change. + +function To_Cursor (Container : Vector; + Index : Extended_Index) return Cursor; + +If Index is not in the range First_Index (Container) .. Last_Index (Container), then No_Element +is returned. Otherwise, a cursor designating the element at position Index in Container is +returned. + +function To_Index (Position : Cursor) return Extended_Index; + +If Position is No_Element, No_Index is returned. Otherwise, the index (within its containing +vector) of the element designated by Position is returned. + +function Element (Container : Vector; + Index : Index_Type) + return Element_Type; + +If Index is not in the range First_Index (Container) +Constraint_Error is propagated. Otherwise, Element returns the element at position Index. + +.. Last_Index (Container), then + +function Element (Position : Cursor) return Element_Type; + +If Position equals No_Element, then Constraint_Error is propagated. Otherwise, Element returns +the element designated by Position. + +procedure Replace_Element (Container : in out Vector; + Index : in Index_Type; + New_Item : in Element_Type); + +If Index is not in the range First_Index (Container) +.. Last_Index (Container), then +Constraint_Error is propagated. Otherwise, Replace_Element assigns the value New_Item to the +element at position Index. Any exception raised during the assignment is propagated. The +element at position Index is not an empty element after successful call to Replace_Element. + +procedure Replace_Element (Container : in out Vector; + Position : in Cursor; + New_Item : in Element_Type); + +If Position equals No_Element, then Constraint_Error is propagated; if Position does not +is propagated. Otherwise, +designate an element + +then Program_Error + +in Container, + +116/2 + +117/2 + +118/2 + +119/3 + +120/2 + +121/2 + +122/2 + +123/2 + +124/2 + +125/2 + +126/2 + +127/2 + +128/2 + +129/2 + +130/2 + +131/2 + +132/2 + +133/3 + +134/2 + +135/3 + +A.18.2 The Generic Package Containers.Vectors + +13 December 2012 482 + + Ada Reference Manual — 2012 Edition + +Replace_Element assigns New_Item to the element designated by Position. Any exception +raised during the assignment is propagated. The element at Position is not an empty element +after successful call to Replace_Element. + +procedure Query_Element + (Container : in Vector; + Index : in Index_Type; + Process : not null access procedure (Element : in Element_Type)); + +.. Last_Index (Container), then +If Index is not in the range First_Index (Container) +Constraint_Error is propagated. Otherwise, Query_Element calls Process.all with the element at +position Index as the argument. Tampering with the elements of Container is prohibited during +the execution of the call on Process.all. Any exception raised by Process.all is propagated. + +procedure Query_Element + (Position : in Cursor; + Process : not null access procedure (Element : in Element_Type)); + +If Position equals No_Element, then Constraint_Error is propagated. Otherwise, Query_Element +calls Process.all with the element designated by Position as the argument. Tampering with the +elements of the vector that contains the element designated by Position is prohibited during the +execution of the call on Process.all. Any exception raised by Process.all is propagated. + +procedure Update_Element + (Container : in out Vector; + Index : in Index_Type; + Process : not null access procedure (Element : in out Element_Type)); + +If Index is not in the range First_Index (Container) +.. Last_Index (Container), then +Constraint_Error is propagated. Otherwise, Update_Element calls Process.all with the element at +position Index as the argument. Tampering with the elements of Container is prohibited during +the execution of the call on Process.all. Any exception raised by Process.all is propagated. + +If Element_Type is unconstrained and definite, then the actual Element parameter of Process.all +shall be unconstrained. + +The element at position Index is not an empty element after successful completion of this +operation. + +procedure Update_Element + (Container : in out Vector; + Position : in Cursor; + Process : not null access procedure (Element : in out Element_Type)); + +If Position equals No_Element, then Constraint_Error is propagated; if Position does not +designate an element +is propagated. Otherwise, +Update_Element calls Process.all with the element designated by Position as the argument. +Tampering with the elements of Container is prohibited during the execution of the call on +Process.all. Any exception raised by Process.all is propagated. + +then Program_Error + +in Container, + +If Element_Type is unconstrained and definite, then the actual Element parameter of Process.all +shall be unconstrained. + +The element designated by Position is not an empty element after successful completion of this +operation. + +type Constant_Reference_Type + (Element : not null access constant Element_Type) is private + with Implicit_Dereference => Element; + +483 13 December 2012 + +The Generic Package Containers.Vectors A.18.2 + +136/2 + +137/3 + +138/2 + +139/3 + +140/2 + +141/3 + +142/2 + +143/2 + +144/2 + +145/3 + +146/2 + +147/2 + +147.1/3 + + 147.2/3 + +147.3/3 + +147.4/3 + +147.5/3 + +147.6/3 + +147.7/3 + +147.8/3 + +147.9/3 + +147.10/3 + +147.11/3 + +147.12/3 + +147.13/3 + +147.14/3 + +147.15/3 + +147.16/3 + +Ada Reference Manual — 2012 Edition + +type Reference_Type (Element : not null access Element_Type) is private + with Implicit_Dereference => Element; + +The types Constant_Reference_Type and Reference_Type need finalization. + +The default initialization of an object of type Constant_Reference_Type or Reference_Type +propagates Program_Error. + +function Constant_Reference (Container : aliased in Vector; + Index : in Index_Type) + return Constant_Reference_Type; + +This function (combined with the Constant_Indexing and Implicit_Dereference aspects) provides +a convenient way to gain read access to an individual element of a vector given an index value. + +.. Last_Index (Container), then +If Index is not in the range First_Index (Container) +Constraint_Error is propagated. Otherwise, Constant_Reference returns an object whose +discriminant is an access value that designates the element at position Index. Tampering with the +elements of Container is prohibited while the object returned by Constant_Reference exists and +has not been finalized. + +function Reference (Container : aliased in out Vector; + Index : in Index_Type) + return Reference_Type; + +This function (combined with the Variable_Indexing and Implicit_Dereference aspects) provides +a convenient way to gain read and write access to an individual element of a vector given an +index value. + +If Index is not in the range First_Index (Container) +.. Last_Index (Container), then +Constraint_Error is propagated. Otherwise, Reference returns an object whose discriminant is an +access value that designates the element at position Index. Tampering with the elements of +Container is prohibited while the object returned by Reference exists and has not been finalized. + +The element at position Index is not an empty element after successful completion of this +operation. + +function Constant_Reference (Container : aliased in Vector; + Position : in Cursor) + return Constant_Reference_Type; + +This function (combined with the Constant_Indexing and Implicit_Dereference aspects) provides +a convenient way to gain read access to an individual element of a vector given a cursor. + +If Position equals No_Element, then Constraint_Error is propagated; if Position does not +designate an element +is propagated. Otherwise, +Constant_Reference returns an object whose discriminant is an access value that designates the +element designated by Position. Tampering with the elements of Container is prohibited while +the object returned by Constant_Reference exists and has not been finalized. + +then Program_Error + +in Container, + +function Reference (Container : aliased in out Vector; + Position : in Cursor) + return Reference_Type; + +This function (combined with the Variable_Indexing and Implicit_Dereference aspects) provides +a convenient way to gain read and write access to an individual element of a vector given a +cursor. + +A.18.2 The Generic Package Containers.Vectors + +13 December 2012 484 + + Ada Reference Manual — 2012 Edition + +If Position equals No_Element, then Constraint_Error is propagated; if Position does not +designate an element in Container, then Program_Error is propagated. Otherwise, Reference +returns an object whose discriminant is an access value that designates the element designated +by Position. Tampering with the elements of Container is prohibited while the object returned by +Reference exists and has not been finalized. + +147.17/3 + +The element designated by Position is not an empty element after successful completion of this +operation. + +147.18/3 + +procedure Assign (Target : in out Vector; Source : in Vector); + +If Target denotes the same object as Source, the operation has no effect. If the length of Source +is greater than the capacity of Target, Reserve_Capacity (Target, Length (Source)) is called. The +elements of Source are then copied to Target as for an assignment_statement assigning Source +to Target (this includes setting the length of Target to be that of Source). + +function Copy (Source : Vector; Capacity : Count_Type := 0) + return Vector; + +Returns a vector whose elements are initialized from the corresponding elements of Source. If +Capacity is 0, then the vector capacity is the length of Source; if Capacity is equal to or greater +than the length of Source, the vector capacity is at least the specified value. Otherwise, the +operation propagates Capacity_Error. + +procedure Move (Target : in out Vector; + Source : in out Vector); + +If Target denotes the same object as Source, then the operation has no effect. Otherwise, Move +first calls Reserve_Capacity (Target, Length (Source)) and then Clear (Target); then, each +element from Source is removed from Source and inserted into Target in the original order. The +length of Source is 0 after a successful call to Move. + +procedure Insert (Container : in out Vector; + Before : in Extended_Index; + New_Item : in Vector); + +If Before is not in the range First_Index (Container) .. Last_Index (Container) + 1, then +Constraint_Error is propagated. If Length(New_Item) is 0, then Insert does nothing. Otherwise, +it computes the new length NL as the sum of the current length and Length (New_Item); if the +value of Last appropriate for length NL would be greater than Index_Type'Last, then +Constraint_Error is propagated. + +If the current vector capacity is less than NL, Reserve_Capacity (Container, NL) is called to +increase the vector capacity. Then Insert slides the elements in the range Before .. Last_Index +(Container) up by Length(New_Item) positions, and then copies the elements of New_Item to +the positions starting at Before. Any exception raised during the copying is propagated. + +procedure Insert (Container : in out Vector; + Before : in Cursor; + New_Item : in Vector); + +If Before is not No_Element, and does not designate an element in Container, then +Program_Error is propagated. Otherwise, if Length(New_Item) is 0, then Insert does nothing. If +Before is No_Element, then the call is equivalent to Insert (Container, Last_Index (Container) + +1, New_Item); otherwise, the call is equivalent to Insert (Container, To_Index (Before), +New_Item); + +147.19/3 + +147.20/3 + +147.21/3 + +147.22/3 + +148/2 + +149/3 + +150/2 + +151/3 + +152/2 + +153/2 + +154/3 + +485 13 December 2012 + +The Generic Package Containers.Vectors A.18.2 + + Ada Reference Manual — 2012 Edition + +procedure Insert (Container : in out Vector; + Before : in Cursor; + New_Item : in Vector; + Position : out Cursor); + +If Before is not No_Element, and does not designate an element in Container, then +Program_Error is propagated. If Before equals No_Element, then let T be Last_Index +(Container) + 1; otherwise, let T be To_Index (Before). Insert (Container, T, New_Item) is +called, and then Position is set to To_Cursor (Container, T). + +procedure Insert (Container : in out Vector; + Before : in Extended_Index; + New_Item : in Element_Type; + Count : in Count_Type := 1); + +Equivalent to Insert (Container, Before, To_Vector (New_Item, Count)); + +procedure Insert (Container : in out Vector; + Before : in Cursor; + New_Item : in Element_Type; + Count : in Count_Type := 1); + +Equivalent to Insert (Container, Before, To_Vector (New_Item, Count)); + +procedure Insert (Container : in out Vector; + Before : in Cursor; + New_Item : in Element_Type; + Position : out Cursor; + Count : in Count_Type := 1); + +Equivalent to Insert (Container, Before, To_Vector (New_Item, Count), Position); + +procedure Insert (Container : in out Vector; + Before : in Extended_Index; + Count : in Count_Type := 1); + +If Before is not in the range First_Index (Container) .. Last_Index (Container) + 1, then +Constraint_Error is propagated. If Count is 0, then Insert does nothing. Otherwise, it computes +the new length NL as the sum of the current length and Count; if the value of Last appropriate +for length NL would be greater than Index_Type'Last, then Constraint_Error is propagated. + +If the current vector capacity is less than NL, Reserve_Capacity (Container, NL) is called to +increase the vector capacity. Then Insert slides the elements in the range Before .. Last_Index +(Container) up by Count positions, and then inserts elements that are initialized by default (see +3.3.1) in the positions starting at Before. + +procedure Insert (Container : in out Vector; + Before : in Cursor; + Position : out Cursor; + Count : in Count_Type := 1); + +If Before is not No_Element, and does not designate an element in Container, then +Program_Error is propagated. If Before equals No_Element, then let T be Last_Index +(Container) + 1; otherwise, let T be To_Index (Before). Insert (Container, T, Count) is called, +and then Position is set to To_Cursor (Container, T). + +procedure Prepend (Container : in out Vector; + New_Item : in Vector; + Count : in Count_Type := 1); + +Equivalent to Insert (Container, First_Index (Container), New_Item). + +155/2 + +156/2 + +157/2 + +158/2 + +159/2 + +160/2 + +161/2 + +162/2 + +163/2 + +164/3 + +165/2 + +166/2 + +167/2 + +168/2 + +169/2 + +A.18.2 The Generic Package Containers.Vectors + +13 December 2012 486 + + Ada Reference Manual — 2012 Edition + +procedure Prepend (Container : in out Vector; + New_Item : in Element_Type; + Count : in Count_Type := 1); + +Equivalent to Insert (Container, First_Index (Container), New_Item, Count). + +procedure Append (Container : in out Vector; + New_Item : in Vector); + +Equivalent to Insert (Container, Last_Index (Container) + 1, New_Item). + +procedure Append (Container : in out Vector; + New_Item : in Element_Type; + Count : in Count_Type := 1); + +Equivalent to Insert (Container, Last_Index (Container) + 1, New_Item, Count). + +procedure Insert_Space (Container : in out Vector; + Before : in Extended_Index; + Count : in Count_Type := 1); + +If Before is not in the range First_Index (Container) .. Last_Index (Container) + 1, then +Constraint_Error is propagated. If Count is 0, then Insert_Space does nothing. Otherwise, it +computes the new length NL as the sum of the current length and Count; if the value of Last +appropriate for length NL would be greater than Index_Type'Last, then Constraint_Error is +propagated. + +If the current vector capacity is less than NL, Reserve_Capacity (Container, NL) is called to +increase the vector capacity. Then Insert_Space slides the elements in the range Before .. +Last_Index (Container) up by Count positions, and then inserts empty elements in the positions +starting at Before. + +procedure Insert_Space (Container : in out Vector; + Before : in Cursor; + Position : out Cursor; + Count : in Count_Type := 1); + +If Before is not No_Element, and does not designate an element in Container, then +Program_Error is propagated. If Before equals No_Element, then let T be Last_Index +(Container) + 1; otherwise, let T be To_Index (Before). Insert_Space (Container, T, Count) is +called, and then Position is set to To_Cursor (Container, T). + +procedure Delete (Container : in out Vector; + Index : in Extended_Index; + Count : in Count_Type := 1); + +If Index is not in the range First_Index (Container) .. Last_Index (Container) + 1, then +Constraint_Error is propagated. If Count is 0, Delete has no effect. Otherwise, Delete slides the +elements (if any) starting at position Index + Count down to Index. Any exception raised during +element assignment is propagated. + +procedure Delete (Container : in out Vector; + Position : in out Cursor; + Count : in Count_Type := 1); + +If Position equals No_Element, then Constraint_Error is propagated. If Position does not +designate an element in Container, then Program_Error is propagated. Otherwise, Delete +(Container, To_Index (Position), Count) is called, and then Position is set to No_Element. + +170/2 + +171/2 + +172/2 + +173/2 + +174/2 + +175/2 + +176/2 + +177/3 + +178/2 + +179/2 + +180/2 + +181/2 + +182/3 + +183/2 + +184/2 + +487 13 December 2012 + +The Generic Package Containers.Vectors A.18.2 + + Ada Reference Manual — 2012 Edition + +185/2 + +186/2 + +187/2 + +188/3 + +189/2 + +190/2 + +191/2 + +192/2 + +193/2 + +194/2 + +195/2 + +196/2 + +197/2 + +198/2 + +199/2 + +200/2 + +201/2 + +202/2 + +203/2 + +204/2 + +205/2 + +206/2 + +207/2 + +208/2 + +procedure Delete_First (Container : in out Vector; + Count : in Count_Type := 1); + +Equivalent to Delete (Container, First_Index (Container), Count). + +procedure Delete_Last (Container : in out Vector; + Count : in Count_Type := 1); + +If Length (Container) <= Count, then Delete_Last is equivalent to Clear (Container). Otherwise, +it is equivalent to Delete (Container, Index_Type'Val(Index_Type'Pos(Last_Index (Container)) – +Count + 1), Count). + +procedure Reverse_Elements (Container : in out Vector); + +Reorders the elements of Container in reverse order. + +procedure Swap (Container : in out Vector; + I, J : in Index_Type); + +If either I or J is not in the range First_Index (Container) .. Last_Index (Container), then +Constraint_Error is propagated. Otherwise, Swap exchanges the values of the elements at +positions I and J. + +procedure Swap (Container : in out Vector; + I, J : in Cursor); + +If either I or J is No_Element, then Constraint_Error is propagated. If either I or J do not +designate an element in Container, then Program_Error is propagated. Otherwise, Swap +exchanges the values of the elements designated by I and J. + +function First_Index (Container : Vector) return Index_Type; + +Returns the value Index_Type'First. + +function First (Container : Vector) return Cursor; + +If Container is empty, First returns No_Element. Otherwise, it returns a cursor that designates +the first element in Container. + +function First_Element (Container : Vector) return Element_Type; + +Equivalent to Element (Container, First_Index (Container)). + +function Last_Index (Container : Vector) return Extended_Index; + +If Container is empty, Last_Index returns No_Index. Otherwise, it returns the position of the last +element in Container. + +function Last (Container : Vector) return Cursor; + +If Container is empty, Last returns No_Element. Otherwise, it returns a cursor that designates the +last element in Container. + +function Last_Element (Container : Vector) return Element_Type; + +Equivalent to Element (Container, Last_Index (Container)). + +function Next (Position : Cursor) return Cursor; + +If Position equals No_Element or designates the last element of the container, then Next returns +the value No_Element. Otherwise, it returns a cursor that designates the element with index +To_Index (Position) + 1 in the same vector as Position. + +A.18.2 The Generic Package Containers.Vectors + +13 December 2012 488 + + Ada Reference Manual — 2012 Edition + +procedure Next (Position : in out Cursor); + +Equivalent to Position := Next (Position). + +function Previous (Position : Cursor) return Cursor; + +If Position equals No_Element or designates the first element of the container, then Previous +returns the value No_Element. Otherwise, it returns a cursor that designates the element with +index To_Index (Position) – 1 in the same vector as Position. + +procedure Previous (Position : in out Cursor); + +Equivalent to Position := Previous (Position). + +function Find_Index (Container : Vector; + Item : Element_Type; + Index : Index_Type := Index_Type'First) + return Extended_Index; + +Searches the elements of Container for an element equal to Item (using the generic formal +equality operator). The search starts at position Index and proceeds towards Last_Index +(Container). If no equal element is found, then Find_Index returns No_Index. Otherwise, it +returns the index of the first equal element encountered. + +function Find (Container : Vector; + Item : Element_Type; + Position : Cursor := No_Element) + return Cursor; + +If Position is not No_Element, and does not designate an element in Container, then +Program_Error is propagated. Otherwise, Find searches the elements of Container for an element +equal to Item (using the generic formal equality operator). The search starts at the first element if +Position equals No_Element, and at the element designated by Position otherwise. It proceeds +towards the last element of Container. If no equal element is found, then Find returns +No_Element. Otherwise, it returns a cursor designating the first equal element encountered. + +function Reverse_Find_Index (Container : Vector; + Item : Element_Type; + Index : Index_Type := Index_Type'Last) + return Extended_Index; + +Searches the elements of Container for an element equal to Item (using the generic formal +equality operator). The search starts at position Index or, if Index is greater than Last_Index +(Container), at position Last_Index (Container). It proceeds towards First_Index (Container). If +no equal element is found, then Reverse_Find_Index returns No_Index. Otherwise, it returns the +index of the first equal element encountered. + +function Reverse_Find (Container : Vector; + Item : Element_Type; + Position : Cursor := No_Element) + return Cursor; + +If Position is not No_Element, and does not designate an element in Container, then +Program_Error is propagated. Otherwise, Reverse_Find searches the elements of Container for +an element equal to Item (using the generic formal equality operator). The search starts at the +last element if Position equals No_Element, and at the element designated by Position otherwise. +It proceeds towards the first element of Container. If no equal element is found, then +Reverse_Find returns No_Element. Otherwise, it returns a cursor designating the first equal +element encountered. + +209/2 + +210/2 + +211/2 + +212/2 + +213/2 + +214/2 + +215/2 + +216/2 + +217/2 + +218/3 + +219/2 + +220/2 + +221/2 + +222/3 + +489 13 December 2012 + +The Generic Package Containers.Vectors A.18.2 + + Ada Reference Manual — 2012 Edition + +223/2 + +224/2 + +227/2 + +228/3 + +229/2 + +230/3 + +230.1/3 + +230.2/3 + +230.3/3 + +230.4/3 + +231/3 + +232/2 + +233/2 + +function Contains (Container : Vector; + Item : Element_Type) return Boolean; + +Equivalent to Has_Element (Find (Container, Item)). + +Paragraphs 225 and 226 were moved above. + +procedure Iterate + (Container : in Vector; + Process : not null access procedure (Position : in Cursor)); + +Invokes Process.all with a cursor that designates each element in Container, in index order. +Tampering with the cursors of Container is prohibited during the execution of a call on +Process.all. Any exception raised by Process.all is propagated. + +procedure Reverse_Iterate + (Container : in Vector; + Process : not null access procedure (Position : in Cursor)); + +Iterates over the elements in Container as per procedure Iterate, except that elements are +traversed in reverse index order. + +function Iterate (Container : in Vector) + return Vector_Iterator_Interfaces.Reversible_Iterator'Class; + +Iterate returns a reversible iterator object (see 5.5.1) that will generate a value for a loop +parameter (see 5.5.2) designating each node in Container, starting with the first node and moving +the cursor as per the Next function when used as a forward iterator, and starting with the last +node and moving the cursor as per the Previous function when used as a reverse iterator. +Tampering with the cursors of Container is prohibited while the iterator object exists (in +particular, in the sequence_of_statements of the loop_statement whose iterator_specification +denotes this object). The iterator object needs finalization. + +function Iterate (Container : in Vector; Start : in Cursor) + return Vector_Iterator_Interfaces.Reversible_Iterator'Class; + +If Start is not No_Element and does not designate an item in Container, then Program_Error is +propagated. If Start is No_Element, then Constraint_Error is propagated. Otherwise, Iterate +returns a reversible iterator object (see 5.5.1) that will generate a value for a loop parameter (see +5.5.2) designating each node in Container, starting with the node designated by Start and moving +the cursor as per the Next function when used as a forward iterator, or moving the cursor as per +the Previous function when used as a reverse iterator. Tampering with the cursors of Container is +prohibited while the iterator object exists (in particular, in the sequence_of_statements of the +loop_statement whose iterator_specification denotes this object). The iterator object needs +finalization. + +The actual function for the generic formal function "<" of Generic_Sorting is expected to return the same +value each time it is called with a particular pair of element values. It should define a strict weak ordering +relationship (see A.18); it should not modify Container. If the actual for "<" behaves in some other +manner, the behavior of the subprograms of Generic_Sorting are unspecified. The number of times the +subprograms of Generic_Sorting call "<" is unspecified. + +function Is_Sorted (Container : Vector) return Boolean; + +Returns True if the elements are sorted smallest first as determined by the generic formal "<" +operator; otherwise, Is_Sorted returns False. Any exception raised during evaluation of "<" is +propagated. + +A.18.2 The Generic Package Containers.Vectors + +13 December 2012 490 + + Ada Reference Manual — 2012 Edition + +procedure Sort (Container : in out Vector); + +Reorders the elements of Container such that the elements are sorted smallest first as determined +by the generic formal "<" operator provided. Any exception raised during evaluation of "<" is +propagated. + +procedure Merge (Target : in out Vector; + Source : in out Vector); + +If Source is empty, then Merge does nothing. If Source and Target are the same nonempty +container object, then Program_Error is propagated. Otherwise, Merge removes elements from +Source and inserts them into Target; afterwards, Target contains the union of the elements that +were initially in Source and Target; Source is left empty. If Target and Source are initially sorted +smallest first, then Target is ordered smallest first as determined by the generic formal "<" +operator; otherwise, the order of elements in Target is unspecified. Any exception raised during +evaluation of "<" is propagated. + +234/2 + +235/2 + +236/2 + +237/3 + +Bounded (Run-Time) Errors + +Reading the value of an empty element by calling Element, Query_Element, Update_Element, +Constant_Reference, Reference, Swap, Is_Sorted, Sort, Merge, "=", Find, or Reverse_Find is a bounded +error. The implementation may treat the element as having any normal value (see 13.9.1) of the element +type, or raise Constraint_Error or Program_Error before modifying the vector. + +238/3 + +Calling Merge in an instance of Generic_Sorting with either Source or Target not ordered smallest first +using the provided generic formal "<" operator is a bounded error. Either Program_Error is raised after +Target is updated as described for Merge, or the operation works as defined. + +239/2 + +It is a bounded error for the actual function associated with a generic formal subprogram, when called as +part of an operation of this package, to tamper with elements of any Vector parameter of the operation. +Either Program_Error is raised, or the operation works as defined on the value of the Vector either prior to, +or subsequent to, some or all of the modifications to the Vector. + +It is a bounded error to call any subprogram declared in the visible part of Containers.Vectors when the +associated container has been finalized. If the operation takes Container as an in out parameter, then it +raises Constraint_Error or Program_Error. Otherwise, the operation either proceeds as it would for an +empty container, or it raises Constraint_Error or Program_Error. + +A Cursor value is ambiguous if any of the following have occurred since it was created: + +• Insert, Insert_Space, or Delete has been called on the vector that contains the element the cursor +designates with an index value (or a cursor designating an element at such an index value) less +than or equal to the index value of the element designated by the cursor; or + +• The vector that contains the element it designates has been passed to the Sort or Merge + +procedures of an instance of Generic_Sorting, or to the Reverse_Elements procedure. + +It is a bounded error to call any subprogram other than "=" or Has_Element declared in Containers.Vectors +with an ambiguous (but not invalid, see below) cursor parameter. Possible results are: + +• The cursor may be treated as if it were No_Element; +• The cursor may designate some element in the vector (but not necessarily the element that it + +originally designated); + +• Constraint_Error may be raised; or +• Program_Error may be raised. + +239.1/3 + +239.2/3 + +240/2 + +241/2 + +242/2 + +243/2 + +244/2 + +245/2 + +246/2 + +247/2 + +491 13 December 2012 + +The Generic Package Containers.Vectors A.18.2 + + Ada Reference Manual — 2012 Edition + +Erroneous Execution + +248/2 + +A Cursor value is invalid if any of the following have occurred since it was created: + +249/2 + +249.1/3 + +• The vector that contains the element it designates has been finalized; +• The vector that contains the element it designates has been used as the Target of a call to Assign, + +or as the target of an assignment_statement; + +250/2 + +• The vector that contains the element it designates has been used as the Source or Target of a call + +to Move; or + +251/3 + +• The element it designates has been deleted or removed from the vector that previously contained + +the element. + +252/2 + +The result of "=" or Has_Element is unspecified if it is called with an invalid cursor parameter. Execution +is erroneous if any other subprogram declared in Containers.Vectors is called with an invalid cursor +parameter. + +252.1/3 + +Execution is erroneous if the vector associated with the result of a call to Reference or Constant_Reference +is finalized before the result object returned by the call to Reference or Constant_Reference is finalized. + +253/2 + +No storage associated with a vector object shall be lost upon assignment or scope exit. + +Implementation Requirements + +254/3 + +The execution of an assignment_statement for a vector shall have the effect of copying the elements +from the source vector object to the target vector object and changing the length of the target object to that +of the source object. + +Implementation Advice + +255/2 + +256/2 + +257/2 + +Containers.Vectors should be implemented similarly to an array. In particular, if the length of a vector is +N, then +• +• + +the worst-case time complexity of Append with Count=1 when N is less than the capacity of the +vector should be O(log N); and + +the worst-case time complexity of Element should be O(log N); + +258/2 + +• + +the worst-case time complexity of Prepend with Count=1 and Delete_First with Count=1 should +be O(N log N). + +259/2 + +The worst-case +instance of +Containers.Vectors.Generic_Sorting should be O(N**2), and the average time complexity should be better +than O(N**2). + +call on procedure Sort of + +complexity of + +time + +an + +a + +260/2 + +Containers.Vectors.Generic_Sorting.Sort and Containers.Vectors.Generic_Sorting.Merge should minimize +copying of elements. + +261/2 + +Move should not copy elements, and should minimize copying of internal data structures. + +262/2 + +If an exception is propagated from a vector operation, no storage should be lost, nor any elements removed +from a vector unless specified by the operation. + +263/2 + +264/2 + +NOTES +48 All elements of a vector occupy locations in the internal array. If a sparse container is required, a Hashed_Map should +be used rather than a vector. + +49 If Index_Type'Base'First = Index_Type'First an instance of Ada.Containers.Vectors will raise Constraint_Error. A +value below Index_Type'First is required so that an empty vector has a meaningful value of Last_Index. + +A.18.2 The Generic Package Containers.Vectors + +13 December 2012 492 + + Ada Reference Manual — 2012 Edition + +A.18.3 The Generic Package Containers.Doubly_Linked_Lists + +The language-defined generic package Containers.Doubly_Linked_Lists provides private types List and +Cursor, and a set of operations for each type. A list container is optimized for insertion and deletion at any +position. + +A doubly-linked list container object manages a linked list of internal nodes, each of which contains an +element and pointers to the next (successor) and previous (predecessor) internal nodes. A cursor designates +a particular node within a list (and by extension the element contained in that node). A cursor keeps +designating the same node (and element) as long as the node is part of the container, even if the node is +moved in the container. + +The length of a list is the number of elements it contains. + +The generic library package Containers.Doubly_Linked_Lists has the following declaration: + +Static Semantics + +with Ada.Iterator_Interfaces; +generic + type Element_Type is private; + with function "=" (Left, Right : Element_Type) + return Boolean is <>; +package Ada.Containers.Doubly_Linked_Lists is + pragma Preelaborate(Doubly_Linked_Lists); + pragma Remote_Types(Doubly_Linked_Lists); + type List is tagged private + with Constant_Indexing => Constant_Reference, + Variable_Indexing => Reference, + Default_Iterator => Iterate, + Iterator_Element => Element_Type; + pragma Preelaborable_Initialization(List); + type Cursor is private; + pragma Preelaborable_Initialization(Cursor); + Empty_List : constant List; + No_Element : constant Cursor; + function Has_Element (Position : Cursor) return Boolean; + package List_Iterator_Interfaces is new + Ada.Iterator_Interfaces (Cursor, Has_Element); + function "=" (Left, Right : List) return Boolean; + function Length (Container : List) return Count_Type; + function Is_Empty (Container : List) return Boolean; + procedure Clear (Container : in out List); + function Element (Position : Cursor) + return Element_Type; + procedure Replace_Element (Container : in out List; + Position : in Cursor; + New_Item : in Element_Type); + procedure Query_Element + (Position : in Cursor; + Process : not null access procedure (Element : in Element_Type)); + procedure Update_Element + (Container : in out List; + Position : in Cursor; + Process : not null access procedure + (Element : in out Element_Type)); + +1/2 + +2/2 + +3/2 + +4/2 + +5/3 + +6/3 + +7/2 + +8/2 + +9/2 + +9.1/3 + +9.2/3 + +10/2 + +11/2 + +12/2 + +13/2 + +14/2 + +15/2 + +16/2 + +17/2 + +493 13 December 2012 + +The Generic Package Containers.Doubly_Linked_Lists A.18.3 + + Ada Reference Manual — 2012 Edition + +17.1/3 + +17.2/3 + +17.3/3 + +17.4/3 + +17.5/3 + +17.6/3 + +18/2 + +19/2 + +20/2 + +21/2 + +22/2 + +23/2 + +24/2 + +25/2 + +26/2 + +27/2 + +28/2 + +29/2 + +30/2 + +31/2 + +32/2 + + type Constant_Reference_Type + (Element : not null access constant Element_Type) is private + with Implicit_Dereference => Element; + type Reference_Type (Element : not null access Element_Type) is private + with Implicit_Dereference => Element; + function Constant_Reference (Container : aliased in List; + Position : in Cursor) + return Constant_Reference_Type; + function Reference (Container : aliased in out List; + Position : in Cursor) + return Reference_Type; + procedure Assign (Target : in out List; Source : in List); + function Copy (Source : List) return List; + procedure Move (Target : in out List; + Source : in out List); + procedure Insert (Container : in out List; + Before : in Cursor; + New_Item : in Element_Type; + Count : in Count_Type := 1); + procedure Insert (Container : in out List; + Before : in Cursor; + New_Item : in Element_Type; + Position : out Cursor; + Count : in Count_Type := 1); + procedure Insert (Container : in out List; + Before : in Cursor; + Position : out Cursor; + Count : in Count_Type := 1); + procedure Prepend (Container : in out List; + New_Item : in Element_Type; + Count : in Count_Type := 1); + procedure Append (Container : in out List; + New_Item : in Element_Type; + Count : in Count_Type := 1); + procedure Delete (Container : in out List; + Position : in out Cursor; + Count : in Count_Type := 1); + procedure Delete_First (Container : in out List; + Count : in Count_Type := 1); + procedure Delete_Last (Container : in out List; + Count : in Count_Type := 1); + procedure Reverse_Elements (Container : in out List); + procedure Swap (Container : in out List; + I, J : in Cursor); + procedure Swap_Links (Container : in out List; + I, J : in Cursor); + procedure Splice (Target : in out List; + Before : in Cursor; + Source : in out List); + procedure Splice (Target : in out List; + Before : in Cursor; + Source : in out List; + Position : in out Cursor); + procedure Splice (Container: in out List; + Before : in Cursor; + Position : in Cursor); + +A.18.3 The Generic Package Containers.Doubly_Linked_Lists + +13 December 2012 494 + + Ada Reference Manual — 2012 Edition + + function First (Container : List) return Cursor; + function First_Element (Container : List) + return Element_Type; + function Last (Container : List) return Cursor; + function Last_Element (Container : List) + return Element_Type; + function Next (Position : Cursor) return Cursor; + function Previous (Position : Cursor) return Cursor; + procedure Next (Position : in out Cursor); + procedure Previous (Position : in out Cursor); + function Find (Container : List; + Item : Element_Type; + Position : Cursor := No_Element) + return Cursor; + function Reverse_Find (Container : List; + Item : Element_Type; + Position : Cursor := No_Element) + return Cursor; + function Contains (Container : List; + Item : Element_Type) return Boolean; +This paragraph was deleted. + procedure Iterate + (Container : in List; + Process : not null access procedure (Position : in Cursor)); + procedure Reverse_Iterate + (Container : in List; + Process : not null access procedure (Position : in Cursor)); + function Iterate (Container : in List) + return List_Iterator_Interfaces.Reversible_Iterator'Class; + function Iterate (Container : in List; Start : in Cursor) + return List_Iterator_Interfaces.Reversible_Iterator'Class; + generic + with function "<" (Left, Right : Element_Type) + return Boolean is <>; + package Generic_Sorting is + function Is_Sorted (Container : List) return Boolean; + procedure Sort (Container : in out List); + procedure Merge (Target : in out List; + Source : in out List); + end Generic_Sorting; +private + ... -- not specified by the language +end Ada.Containers.Doubly_Linked_Lists; + +The actual function for the generic formal function "=" on Element_Type values is expected to define a +reflexive and symmetric relationship and return the same result value each time it is called with a +particular pair of values. If it behaves in some other manner, the functions Find, Reverse_Find, and "=" on +list values return an unspecified value. The exact arguments and number of calls of this generic formal +function by the functions Find, Reverse_Find, and "=" on list values are unspecified. + +The type List is used to represent lists. The type List needs finalization (see 7.6). + +Empty_List represents the empty List object. It has a length of 0. If an object of type List is not otherwise +initialized, it is initialized to the same value as Empty_List. + +495 13 December 2012 + +The Generic Package Containers.Doubly_Linked_Lists A.18.3 + +33/2 + +34/2 + +35/2 + +36/2 + +37/2 + +38/2 + +39/2 + +40/2 + +41/2 + +42/2 + +43/2 + +44/3 + +45/2 + +46/2 + +46.1/3 + +46.2/3 + +47/2 + +48/2 + +49/2 + +50/2 + +51/2 + +52/2 + +53/2 + +54/2 + +55/2 + +56/2 + +57/2 + + Ada Reference Manual — 2012 Edition + +58/2 + +59/2 + +60/2 + +No_Element represents a cursor that designates no element. If an object of type Cursor is not otherwise +initialized, it is initialized to the same value as No_Element. + +The predefined "=" operator for type Cursor returns True if both cursors are No_Element, or designate the +same element in the same container. + +Execution of the default implementation of the Input, Output, Read, or Write attribute of type Cursor +raises Program_Error. + +60.1/3 + +List'Write for a List object L writes Length(L) elements of the list to the stream. It also may write +additional information about the list. + +60.2/3 + +List'Read reads the representation of a list from the stream, and assigns to Item a list with the same length +and elements as was written by List'Write. + +61/2 + +62/2 + +63/2 + +64/2 + +65/2 + +65.1/3 + +66/2 + +67/2 + +68/2 + +69/2 + +69.1/3 + +69.2/3 + +69.3/3 + +70/2 + +71/3 + +Some operations of this generic package have access-to-subprogram parameters. To ensure such +operations are well-defined, they guard against certain actions by the designated subprogram. In particular, +some operations check for “tampering with cursors” of a container because they depend on the set of +elements of the container remaining constant, and others check for “tampering with elements” of a +container because they depend on elements of the container not being replaced. + +A subprogram is said to tamper with cursors of a list object L if: + +• + +• + +• +• +• + +it inserts or deletes elements of L, that is, it calls the Insert, Clear, Delete, or Delete_Last +procedures with L as a parameter; or + +it reorders the elements of L, that is, it calls the Splice, Swap_Links, or Reverse_Elements +procedures or the Sort or Merge procedures of an instance of Generic_Sorting with L as a +parameter; or + +it finalizes L; or + +it calls the Assign procedure with L as the Target parameter; or + +it calls the Move procedure with L as a parameter. + +A subprogram is said to tamper with elements of a list object L if: + +• +• + +it tampers with cursors of L; or + +it replaces one or more elements of L, that is, it calls the Replace_Element or Swap procedures +with L as a parameter. + +When tampering with cursors is prohibited for a particular list object L, Program_Error is propagated by a +call of any language-defined subprogram that is defined to tamper with the cursors of L, leaving L +unmodified. Similarly, when tampering with elements is prohibited for a particular list object L, +Program_Error is propagated by a call of any language-defined subprogram that is defined to tamper with +the elements of L (or tamper with the cursors of L), leaving L unmodified. + +function Has_Element (Position : Cursor) return Boolean; + +Returns True if Position designates an element, and returns False otherwise. + +function "=" (Left, Right : List) return Boolean; + +If Left and Right denote the same list object, then the function returns True. If Left and Right +have different lengths, then the function returns False. Otherwise, it compares each element in +Left to the corresponding element in Right using the generic formal equality operator. If any +such comparison returns False, the function returns False; otherwise, it returns True. Any +exception raised during evaluation of element equality is propagated. + +A.18.3 The Generic Package Containers.Doubly_Linked_Lists + +13 December 2012 496 + + Ada Reference Manual — 2012 Edition + +function Length (Container : List) return Count_Type; + +Returns the number of elements in Container. + +function Is_Empty (Container : List) return Boolean; + +Equivalent to Length (Container) = 0. + +procedure Clear (Container : in out List); + +Removes all the elements from Container. + +function Element (Position : Cursor) return Element_Type; + +If Position equals No_Element, then Constraint_Error is propagated. Otherwise, Element returns +the element designated by Position. + +procedure Replace_Element (Container : in out List; + Position : in Cursor; + New_Item : in Element_Type); + +If Position equals No_Element, then Constraint_Error is propagated; if Position does not +is propagated. Otherwise, +designate an element +Replace_Element assigns the value New_Item to the element designated by Position. + +then Program_Error + +in Container, + +procedure Query_Element + (Position : in Cursor; + Process : not null access procedure (Element : in Element_Type)); + +If Position equals No_Element, then Constraint_Error is propagated. Otherwise, Query_Element +calls Process.all with the element designated by Position as the argument. Tampering with the +elements of the list that contains the element designated by Position is prohibited during the +execution of the call on Process.all. Any exception raised by Process.all is propagated. + +procedure Update_Element + (Container : in out List; + Position : in Cursor; + Process : not null access procedure (Element : in out Element_Type)); + +If Position equals No_Element, then Constraint_Error is propagated; if Position does not +designate an element +is propagated. Otherwise, +Update_Element calls Process.all with the element designated by Position as the argument. +Tampering with the elements of Container is prohibited during the execution of the call on +Process.all. Any exception raised by Process.all is propagated. + +then Program_Error + +in Container, + +72/2 + +73/2 + +74/2 + +75/2 + +76/2 + +77/2 + +78/2 + +79/2 + +80/2 + +81/3 + +82/2 + +83/3 + +84/2 + +85/3 + +If Element_Type is unconstrained and definite, then the actual Element parameter of Process.all +shall be unconstrained. + +86/2 + +type Constant_Reference_Type + (Element : not null access constant Element_Type) is private + with Implicit_Dereference => Element; +type Reference_Type (Element : not null access Element_Type) is private + with Implicit_Dereference => Element; + +The types Constant_Reference_Type and Reference_Type need finalization. + +The default initialization of an object of type Constant_Reference_Type or Reference_Type +propagates Program_Error. + +86.1/3 + +86.2/3 + +86.3/3 + +86.4/3 + +497 13 December 2012 + +The Generic Package Containers.Doubly_Linked_Lists A.18.3 + + 86.5/3 + +86.6/3 + +86.7/3 + +86.8/3 + +86.9/3 + +86.10/3 + +86.11/3 + +86.12/3 + +86.13/3 + +86.14/3 + +87/2 + +88/3 + +89/2 + +90/2 + +91/2 + +92/3 + +Ada Reference Manual — 2012 Edition + +function Constant_Reference (Container : aliased in List; + Position : in Cursor) + return Constant_Reference_Type; + +This function (combined with the Constant_Indexing and Implicit_Dereference aspects) provides +a convenient way to gain read access to an individual element of a list given a cursor. + +If Position equals No_Element, then Constraint_Error is propagated; if Position does not +designate an element +is propagated. Otherwise, +Constant_Reference returns an object whose discriminant is an access value that designates the +element designated by Position. Tampering with the elements of Container is prohibited while +the object returned by Constant_Reference exists and has not been finalized. + +then Program_Error + +in Container, + +function Reference (Container : aliased in out List; + Position : in Cursor) + return Reference_Type; + +This function (combined with the Variable_Indexing and Implicit_Dereference aspects) provides +a convenient way to gain read and write access to an individual element of a list given a cursor. + +If Position equals No_Element, then Constraint_Error is propagated; if Position does not +designate an element in Container, then Program_Error is propagated. Otherwise, Reference +returns an object whose discriminant is an access value that designates the element designated +by Position. Tampering with the elements of Container is prohibited while the object returned by +Reference exists and has not been finalized. + +procedure Assign (Target : in out List; Source : in List); + +If Target denotes the same object as Source, the operation has no effect. Otherwise, the elements +of Source are copied to Target as for an assignment_statement assigning Source to Target. + +function Copy (Source : List) return List; + +Returns a list whose elements match the elements of Source. + +procedure Move (Target : in out List; + Source : in out List); + +If Target denotes the same object as Source, then the operation has no effect. Otherwise, the +operation is equivalent to Assign (Target, Source) followed by Clear (Source). + +procedure Insert (Container : in out List; + Before : in Cursor; + New_Item : in Element_Type; + Count : in Count_Type := 1); + +If Before is not No_Element, and does not designate an element in Container, then +Program_Error is propagated. Otherwise, Insert inserts Count copies of New_Item prior to the +element designated by Before. If Before equals No_Element, the new elements are inserted after +the last node (if any). Any exception raised during allocation of internal storage is propagated, +and Container is not modified. + +procedure Insert (Container : in out List; + Before : in Cursor; + New_Item : in Element_Type; + Position : out Cursor; + Count : in Count_Type := 1); + +If Before is not No_Element, and does not designate an element in Container, then +Program_Error is propagated. Otherwise, Insert allocates Count copies of New_Item, and inserts + +A.18.3 The Generic Package Containers.Doubly_Linked_Lists + +13 December 2012 498 + + Ada Reference Manual — 2012 Edition + +them prior to the element designated by Before. If Before equals No_Element, the new elements +are inserted after the last element (if any). Position designates the first newly-inserted element, +or if Count equals 0, then Position is assigned the value of Before. Any exception raised during +allocation of internal storage is propagated, and Container is not modified. + +procedure Insert (Container : in out List; + Before : in Cursor; + Position : out Cursor; + Count : in Count_Type := 1); + +If Before is not No_Element, and does not designate an element in Container, then +Program_Error is propagated. Otherwise, Insert inserts Count new elements prior to the element +designated by Before. If Before equals No_Element, the new elements are inserted after the last +node (if any). The new elements are initialized by default (see 3.3.1). Position designates the +first newly-inserted element, or if Count equals 0, then Position is assigned the value of Before. +Any exception raised during allocation of internal storage is propagated, and Container is not +modified. + +procedure Prepend (Container : in out List; + New_Item : in Element_Type; + Count : in Count_Type := 1); + +Equivalent to Insert (Container, First (Container), New_Item, Count). + +procedure Append (Container : in out List; + New_Item : in Element_Type; + Count : in Count_Type := 1); + +Equivalent to Insert (Container, No_Element, New_Item, Count). + +procedure Delete (Container : in out List; + Position : in out Cursor; + Count : in Count_Type := 1); + +If Position equals No_Element, then Constraint_Error is propagated. If Position does not +designate an element in Container, then Program_Error is propagated. Otherwise, Delete +removes (from Container) Count elements starting at the element designated by Position (or all +of the elements starting at Position if there are fewer than Count elements starting at Position). +Finally, Position is set to No_Element. + +procedure Delete_First (Container : in out List; + Count : in Count_Type := 1); + +If Length (Container) <= Count, then Delete_First is equivalent to Clear (Container). Otherwise, +it removes the first Count nodes from Container. + +procedure Delete_Last (Container : in out List; + Count : in Count_Type := 1); + +If Length (Container) <= Count, then Delete_Last is equivalent to Clear (Container). Otherwise, +it removes the last Count nodes from Container. + +procedure Reverse_Elements (Container : in out List); + +Reorders the elements of Container in reverse order. + +93/2 + +94/3 + +95/2 + +96/2 + +97/2 + +98/2 + +99/2 + +100/3 + +101/2 + +102/3 + +103/2 + +104/3 + +105/2 + +106/2 + +499 13 December 2012 + +The Generic Package Containers.Doubly_Linked_Lists A.18.3 + + Ada Reference Manual — 2012 Edition + +procedure Swap (Container : in out List; + I, J : in Cursor); + +If either I or J is No_Element, then Constraint_Error is propagated. If either I or J do not +designate an element in Container, then Program_Error is propagated. Otherwise, Swap +exchanges the values of the elements designated by I and J. + +procedure Swap_Links (Container : in out List; + I, J : in Cursor); + +If either I or J is No_Element, then Constraint_Error is propagated. If either I or J do not +designate an element in Container, then Program_Error is propagated. Otherwise, Swap_Links +exchanges the nodes designated by I and J. + +procedure Splice (Target : in out List; + Before : in Cursor; + Source : in out List); + +If Before is not No_Element, and does not designate an element in Target, then Program_Error +is propagated. Otherwise, if Source denotes the same object as Target, the operation has no +effect. Otherwise, Splice reorders elements such that they are removed from Source and moved +to Target, immediately prior to Before. If Before equals No_Element, the nodes of Source are +spliced after the last node of Target. The length of Target is incremented by the number of nodes +in Source, and the length of Source is set to 0. + +procedure Splice (Target : in out List; + Before : in Cursor; + Source : in out List; + Position : in out Cursor); + +If Position is No_Element, then Constraint_Error is propagated. If Before does not equal +No_Element, and does not designate an element in Target, then Program_Error is propagated. If +Position does not equal No_Element, and does not designate a node in Source, then +Program_Error is propagated. If Source denotes the same object as Target, then there is no effect +if Position equals Before, else the element designated by Position is moved immediately prior to +Before, or, if Before equals No_Element, after the last element. In both cases, Position and the +length of Target are unchanged. Otherwise, the element designated by Position is removed from +Source and moved to Target, immediately prior to Before, or, if Before equals No_Element, +after the last element of Target. The length of Target is incremented, the length of Source is +decremented, and Position is updated to represent an element in Target. + +procedure Splice (Container: in out List; + Before : in Cursor; + Position : in Cursor); + +If Position is No_Element, then Constraint_Error is propagated. If Before does not equal +No_Element, and does not designate an element in Container, then Program_Error is propagated. +If Position does not equal No_Element, and does not designate a node in Container, then +Program_Error is propagated. If Position equals Before there is no effect. Otherwise, the element +designated by Position is moved immediately prior to Before, or, if Before equals No_Element, +after the last element. The length of Container is unchanged. + +function First (Container : List) return Cursor; + +If Container is empty, First returns the value No_Element. Otherwise, it returns a cursor that +designates the first node in Container. + +107/2 + +108/2 + +109/2 + +110/2 + +111/2 + +112/2 + +113/2 + +114/3 + +115/2 + +116/3 + +117/2 + +118/3 + +A.18.3 The Generic Package Containers.Doubly_Linked_Lists + +13 December 2012 500 + + Ada Reference Manual — 2012 Edition + +function First_Element (Container : List) return Element_Type; + +Equivalent to Element (First (Container)). + +function Last (Container : List) return Cursor; + +If Container is empty, Last returns the value No_Element. Otherwise, it returns a cursor that +designates the last node in Container. + +function Last_Element (Container : List) return Element_Type; + +Equivalent to Element (Last (Container)). + +function Next (Position : Cursor) return Cursor; + +If Position equals No_Element or designates the last element of the container, then Next returns +the value No_Element. Otherwise, it returns a cursor that designates the successor of the element +designated by Position. + +function Previous (Position : Cursor) return Cursor; + +If Position equals No_Element or designates the first element of the container, then Previous +returns the value No_Element. Otherwise, it returns a cursor that designates the predecessor of +the element designated by Position. + +procedure Next (Position : in out Cursor); + +Equivalent to Position := Next (Position). + +procedure Previous (Position : in out Cursor); + +Equivalent to Position := Previous (Position). + +function Find (Container : List; + Item : Element_Type; + Position : Cursor := No_Element) + return Cursor; + +If Position is not No_Element, and does not designate an element in Container, then +Program_Error is propagated. Find searches the elements of Container for an element equal to +Item (using the generic formal equality operator). The search starts at the element designated by +Position, or at the first element if Position equals No_Element. It proceeds towards Last +(Container). If no equal element is found, then Find returns No_Element. Otherwise, it returns a +cursor designating the first equal element encountered. + +function Reverse_Find (Container : List; + Item : Element_Type; + Position : Cursor := No_Element) + return Cursor; + +If Position is not No_Element, and does not designate an element in Container, then +Program_Error is propagated. Find searches the elements of Container for an element equal to +Item (using the generic formal equality operator). The search starts at the element designated by +Position, or at the last element if Position equals No_Element. It proceeds towards First +(Container). If no equal element is found, then Reverse_Find returns No_Element. Otherwise, it +returns a cursor designating the first equal element encountered. + +function Contains (Container : List; + Item : Element_Type) return Boolean; + +Equivalent to Find (Container, Item) /= No_Element. + +501 13 December 2012 + +The Generic Package Containers.Doubly_Linked_Lists A.18.3 + +119/2 + +120/2 + +121/2 + +122/3 + +123/2 + +124/2 + +125/2 + +126/2 + +127/2 + +128/2 + +129/2 + +130/2 + +131/2 + +132/2 + +133/2 + +134/2 + +135/2 + +136/2 + +137/2 + +138/2 + + Ada Reference Manual — 2012 Edition + +141/2 + +142/3 + +143/2 + +144/3 + +144.1/3 + +144.2/3 + +144.3/3 + +144.4/3 + +145/3 + +146/2 + +147/2 + +Paragraphs 139 and 140 were moved above. + +procedure Iterate + (Container : in List; + Process : not null access procedure (Position : in Cursor)); + +Iterate calls Process.all with a cursor that designates each node in Container, starting with the +first node and moving the cursor as per the Next function. Tampering with the cursors of +Container is prohibited during the execution of a call on Process.all. Any exception raised by +Process.all is propagated. + +procedure Reverse_Iterate + (Container : in List; + Process : not null access procedure (Position : in Cursor)); + +Iterates over the nodes in Container as per procedure Iterate, except that elements are traversed +in reverse order, starting with the last node and moving the cursor as per the Previous function. + +function Iterate (Container : in List) + return List_Iterator_Interfaces.Reversible_Iterator'Class; + +Iterate returns a reversible iterator object (see 5.5.1) that will generate a value for a loop +parameter (see 5.5.2) designating each node in Container, starting with the first node and moving +the cursor as per the Next function when used as a forward iterator, and starting with the last +node and moving the cursor as per the Previous function when used as a reverse iterator. +Tampering with the cursors of Container is prohibited while the iterator object exists (in +particular, in the sequence_of_statements of the loop_statement whose iterator_specification +denotes this object). The iterator object needs finalization. + +function Iterate (Container : in List; Start : in Cursor) + return List_Iterator_Interfaces.Reversible_Iterator'Class; + +If Start is not No_Element and does not designate an item in Container, then Program_Error is +propagated. If Start is No_Element, then Constraint_Error is propagated. Otherwise, Iterate +returns a reversible iterator object (see 5.5.1) that will generate a value for a loop parameter (see +5.5.2) designating each node in Container, starting with the node designated by Start and moving +the cursor as per the Next function when used as a forward iterator, or moving the cursor as per +the Previous function when used as a reverse iterator. Tampering with the cursors of Container is +prohibited while the iterator object exists (in particular, in the sequence_of_statements of the +loop_statement whose iterator_specification denotes this object). The iterator object needs +finalization. + +The actual function for the generic formal function "<" of Generic_Sorting is expected to return the same +value each time it is called with a particular pair of element values. It should define a strict weak ordering +relationship (see A.18); it should not modify Container. If the actual for "<" behaves in some other +manner, the behavior of the subprograms of Generic_Sorting are unspecified. The number of times the +subprograms of Generic_Sorting call "<" is unspecified. + +function Is_Sorted (Container : List) return Boolean; + +Returns True if the elements are sorted smallest first as determined by the generic formal "<" +operator; otherwise, Is_Sorted returns False. Any exception raised during evaluation of "<" is +propagated. + +A.18.3 The Generic Package Containers.Doubly_Linked_Lists + +13 December 2012 502 + + Ada Reference Manual — 2012 Edition + +procedure Sort (Container : in out List); + +Reorders the nodes of Container such that the elements are sorted smallest first as determined by +the generic formal "<" operator provided. The sort is stable. Any exception raised during +evaluation of "<" is propagated. + +procedure Merge (Target : in out List; + Source : in out List); + +If Source is empty, then Merge does nothing. If Source and Target are the same nonempty +container object, then Program_Error is propagated. Otherwise, Merge removes elements from +Source and inserts them into Target; afterwards, Target contains the union of the elements that +were initially in Source and Target; Source is left empty. If Target and Source are initially sorted +smallest first, then Target is ordered smallest first as determined by the generic formal "<" +operator; otherwise, the order of elements in Target is unspecified. Any exception raised during +evaluation of "<" is propagated. + +148/2 + +149/2 + +150/2 + +151/3 + +Calling Merge in an instance of Generic_Sorting with either Source or Target not ordered smallest first +using the provided generic formal "<" operator is a bounded error. Either Program_Error is raised after +Target is updated as described for Merge, or the operation works as defined. + +152/2 + +Bounded (Run-Time) Errors + +It is a bounded error for the actual function associated with a generic formal subprogram, when called as +part of an operation of this package, to tamper with elements of any List parameter of the operation. Either +Program_Error is raised, or the operation works as defined on the value of the List either prior to, or +subsequent to, some or all of the modifications to the List. + +is + +to + +error + +a bounded + +It +the visible part of +Containers.Doubly_Linked_Lists when the associated container has been finalized. If the operation takes +Container as an in out parameter, then it raises Constraint_Error or Program_Error. Otherwise, the +operation either proceeds as it would for an empty container, or it raises Constraint_Error or +Program_Error. + +subprogram declared + +any + +call + +in + +Erroneous Execution + +A Cursor value is invalid if any of the following have occurred since it was created: + +• The list that contains the element it designates has been finalized; +• The list that contains the element it designates has been used as the Target of a call to Assign, or + +as the target of an assignment_statement; + +• The list that contains the element it designates has been used as the Source or Target of a call to + +Move; or + +• The element it designates has been removed from the list that previously contained the element. + +The result of "=" or Has_Element is unspecified if it is called with an invalid cursor parameter. Execution +is erroneous if any other subprogram declared in Containers.Doubly_Linked_Lists is called with an invalid +cursor parameter. + +152.1/3 + +152.2/3 + +153/2 + +154/2 + +154.1/3 + +155/2 + +156/3 + +157/2 + +Execution is erroneous if the list associated with the result of a call to Reference or Constant_Reference is +finalized before the result object returned by the call to Reference or Constant_Reference is finalized. + +157.1/3 + +No storage associated with a doubly-linked List object shall be lost upon assignment or scope exit. + +158/2 + +Implementation Requirements + +503 13 December 2012 + +The Generic Package Containers.Doubly_Linked_Lists A.18.3 + + Ada Reference Manual — 2012 Edition + +159/3 + +The execution of an assignment_statement for a list shall have the effect of copying the elements from +the source list object to the target list object and changing the length of the target object to that of the +source object. + +160/2 + +161/2 + +Containers.Doubly_Linked_Lists should be implemented similarly to a linked list. In particular, if N is the +length of a list, then the worst-case time complexity of Element, Insert with Count=1, and Delete with +Count=1 should be O(log N). + +Implementation Advice + +The worst-case +instance of +Containers.Doubly_Linked_Lists.Generic_Sorting should be O(N**2), and the average time complexity +should be better than O(N**2). + +call on procedure Sort of + +complexity of + +time + +an + +a + +162/2 + +Move should not copy elements, and should minimize copying of internal data structures. + +163/2 + +If an exception is propagated from a list operation, no storage should be lost, nor any elements removed +from a list unless specified by the operation. + +164/2 + +NOTES +50 Sorting a list never copies elements, and is a stable sort (equal elements remain in the original order). This is different +than sorting an array or vector, which may need to copy elements, and is probably not a stable sort. + +A.18.4 Maps + +1/2 + +2/3 + +3/2 + +4/2 + +5/2 + +6/2 + +The language-defined generic packages Containers.Hashed_Maps and Containers.Ordered_Maps provide +private types Map and Cursor, and a set of operations for each type. A map container allows an arbitrary +type to be used as a key to find the element associated with that key. A hashed map uses a hash function to +organize the keys, while an ordered map orders the keys per a specified relation. + +This subclause describes the declarations that are common to both kinds of maps. See A.18.5 for a +description of the semantics specific to Containers.Hashed_Maps and A.18.6 for a description of the +semantics specific to Containers.Ordered_Maps. + +Static Semantics + +The actual function for the generic formal function "=" on Element_Type values is expected to define a +reflexive and symmetric relationship and return the same result value each time it is called with a +particular pair of values. If it behaves in some other manner, the function "=" on map values returns an +unspecified value. The exact arguments and number of calls of this generic formal function by the function +"=" on map values are unspecified. + +The type Map is used to represent maps. The type Map needs finalization (see 7.6). + +A map contains pairs of keys and elements, called nodes. Map cursors designate nodes, but also can be +thought of as designating an element (the element contained in the node) for consistency with the other +containers. There exists an equivalence relation on keys, whose definition is different for hashed maps and +ordered maps. A map never contains two or more nodes with equivalent keys. The length of a map is the +number of nodes it contains. + +Each nonempty map has two particular nodes called the first node and the last node (which may be the +same). Each node except for the last node has a successor node. If there are no other intervening +operations, starting with the first node and repeatedly going to the successor node will visit each node in +the map exactly once until the last node is reached. The exact definition of these terms is different for +hashed maps and ordered maps. + +A.18.3 The Generic Package Containers.Doubly_Linked_Lists + +13 December 2012 504 + + Ada Reference Manual — 2012 Edition + +Some operations of these generic packages have access-to-subprogram parameters. To ensure such +operations are well-defined, they guard against certain actions by the designated subprogram. In particular, +some operations check for “tampering with cursors” of a container because they depend on the set of +elements of the container remaining constant, and others check for “tampering with elements” of a +container because they depend on elements of the container not being replaced. + +7/2 + +A subprogram is said to tamper with cursors of a map object M if: + +• + +• +• +• +• + +it inserts or deletes elements of M, that is, it calls the Insert, Include, Clear, Delete, or Exclude +procedures with M as a parameter; or + +it finalizes M; or + +it calls the Assign procedure with M as the Target parameter; or + +it calls the Move procedure with M as a parameter; or + +it calls one of the operations defined to tamper with the cursors of M. + +A subprogram is said to tamper with elements of a map object M if: + +• +• + +it tampers with cursors of M; or + +it replaces one or more elements of M, that is, it calls the Replace or Replace_Element +procedures with M as a parameter. + +When tampering with cursors is prohibited for a particular map object M, Program_Error is propagated by +a call of any language-defined subprogram that is defined to tamper with the cursors of M, leaving M +unmodified. Similarly, when tampering with elements is prohibited for a particular map object M, +Program_Error is propagated by a call of any language-defined subprogram that is defined to tamper with +the elements of M (or tamper with the cursors of M), leaving M unmodified. + +Empty_Map represents the empty Map object. It has a length of 0. If an object of type Map is not +otherwise initialized, it is initialized to the same value as Empty_Map. + +No_Element represents a cursor that designates no node. If an object of type Cursor is not otherwise +initialized, it is initialized to the same value as No_Element. + +The predefined "=" operator for type Cursor returns True if both cursors are No_Element, or designate the +same element in the same container. + +Execution of the default implementation of the Input, Output, Read, or Write attribute of type Cursor +raises Program_Error. + +8/2 + +9/2 + +10/2 + +10.1/3 + +11/2 + +12/2 + +13/2 + +14/2 + +15/2 + +15.1/3 + +16/2 + +17/2 + +18/2 + +19/2 + +Map'Write for a Map object M writes Length(M) elements of the map to the stream. It also may write +additional information about the map. + +19.1/3 + +Map'Read reads the representation of a map from the stream, and assigns to Item a map with the same +length and elements as was written by Map'Write. + +function Has_Element (Position : Cursor) return Boolean; + +Returns True if Position designates an element, and returns False otherwise. + +function "=" (Left, Right : Map) return Boolean; + +If Left and Right denote the same map object, then the function returns True. If Left and Right +have different lengths, then the function returns False. Otherwise, for each key K in Left, the +function returns False if: + +• a key equivalent to K is not present in Right; or + +19.2/3 + +19.3/3 + +19.4/3 + +20/2 + +21/2 + +22/2 + +505 13 December 2012 + +Maps A.18.4 + + 23/2 + +24/2 + +25/2 + +26/2 + +27/2 + +28/2 + +29/2 + +30/2 + +31/2 + +32/2 + +33/2 + +34/2 + +35/2 + +36/3 + +37/2 + +38/3 + +39/2 + +40/3 + +41/2 + +Ada Reference Manual — 2012 Edition + +• + +the element associated with K in Left is not equal to the element associated with K in +Right (using the generic formal equality operator for elements). + +If the function has not returned a result after checking all of the keys, it returns True. Any +exception raised during evaluation of key equivalence or element equality is propagated. + +function Length (Container : Map) return Count_Type; + +Returns the number of nodes in Container. + +function Is_Empty (Container : Map) return Boolean; + +Equivalent to Length (Container) = 0. + +procedure Clear (Container : in out Map); + +Removes all the nodes from Container. + +function Key (Position : Cursor) return Key_Type; + +If Position equals No_Element, then Constraint_Error is propagated. Otherwise, Key returns the +key component of the node designated by Position. + +function Element (Position : Cursor) return Element_Type; + +If Position equals No_Element, then Constraint_Error is propagated. Otherwise, Element returns +the element component of the node designated by Position. + +procedure Replace_Element (Container : in out Map; + Position : in Cursor; + New_Item : in Element_Type); + +If Position equals No_Element, then Constraint_Error is propagated; if Position does not +is propagated. Otherwise, +designate an element +Replace_Element assigns New_Item to the element of the node designated by Position. + +then Program_Error + +in Container, + +procedure Query_Element + (Position : in Cursor; + Process : not null access procedure (Key : in Key_Type; + Element : in Element_Type)); + +If Position equals No_Element, then Constraint_Error is propagated. Otherwise, Query_Element +calls Process.all with the key and element from the node designated by Position as the +arguments. Tampering with the elements of the map that contains the element designated by +Position is prohibited during the execution of the call on Process.all. Any exception raised by +Process.all is propagated. + +procedure Update_Element + (Container : in out Map; + Position : in Cursor; + Process : not null access procedure (Key : in Key_Type; + Element : in out Element_Type)); + +If Position equals No_Element, then Constraint_Error is propagated; if Position does not +designate an element +is propagated. Otherwise, +Update_Element calls Process.all with the key and element from the node designated by +Position as the arguments. Tampering with the elements of Container is prohibited during the +execution of the call on Process.all. Any exception raised by Process.all is propagated. + +then Program_Error + +in Container, + +If Element_Type is unconstrained and definite, then the actual Element parameter of Process.all +shall be unconstrained. + +A.18.4 Maps + +13 December 2012 506 + + Ada Reference Manual — 2012 Edition + +type Constant_Reference_Type + (Element : not null access constant Element_Type) is private + with Implicit_Dereference => Element; +type Reference_Type (Element : not null access Element_Type) is private + with Implicit_Dereference => Element; + +The types Constant_Reference_Type and Reference_Type need finalization. + +The default initialization of an object of type Constant_Reference_Type or Reference_Type +propagates Program_Error. + +function Constant_Reference (Container : aliased in Map; + Position : in Cursor) + return Constant_Reference_Type; + +41.1/3 + +41.2/3 + +41.3/3 + +41.4/3 + +41.5/3 + +This function (combined with the Constant_Indexing and Implicit_Dereference aspects) provides +a convenient way to gain read access to an individual element of a map given a cursor. + +41.6/3 + +If Position equals No_Element, then Constraint_Error is propagated; if Position does not +designate an element +is propagated. Otherwise, +Constant_Reference returns an object whose discriminant is an access value that designates the +element designated by Position. Tampering with the elements of Container is prohibited while +the object returned by Constant_Reference exists and has not been finalized. + +then Program_Error + +in Container, + +function Reference (Container : aliased in out Map; + Position : in Cursor) + return Reference_Type; + +41.7/3 + +41.8/3 + +This function (combined with the Variable_Indexing and Implicit_Dereference aspects) provides +a convenient way to gain read and write access to an individual element of a map given a cursor. + +41.9/3 + +If Position equals No_Element, then Constraint_Error is propagated; if Position does not +designate an element in Container, then Program_Error is propagated. Otherwise, Reference +returns an object whose discriminant is an access value that designates the element designated +by Position. Tampering with the elements of Container is prohibited while the object returned by +Reference exists and has not been finalized. + +function Constant_Reference (Container : aliased in Map; + Key : in Key_Type) + return Constant_Reference_Type; + +41.10/3 + +41.11/3 + +This function (combined with the Constant_Indexing and Implicit_Dereference aspects) provides +a convenient way to gain read access to an individual element of a map given a key value. + +41.12/3 + +Equivalent to Constant_Reference (Container, Find (Container, Key)). + +function Reference (Container : aliased in out Map; + Key : in Key_Type) + return Reference_Type; + +This function (combined with the Variable_Indexing and Implicit_Dereference aspects) provides +a convenient way to gain read and write access to an individual element of a map given a key +value. + +Equivalent to Reference (Container, Find (Container, Key)). + +41.13/3 + +41.14/3 + +41.15/3 + +41.16/3 + +507 13 December 2012 + +Maps A.18.4 + + Ada Reference Manual — 2012 Edition + +41.17/3 + +41.18/3 + +procedure Assign (Target : in out Map; Source : in Map); + +If Target denotes the same object as Source, the operation has no effect. Otherwise, the +key/element pairs of Source are copied to Target as for an assignment_statement assigning +Source to Target. + +42/2 + +43/3 + +44/2 + +45/2 + +46/2 + +47/2 + +48/2 + +49/2 + +50/2 + +51/2 + +52/2 + +53/2 + +procedure Move (Target : in out Map; + Source : in out Map); + +If Target denotes the same object as Source, then the operation has no effect. Otherwise, the +operation is equivalent to Assign (Target, Source) followed by Clear (Source). + +procedure Insert (Container : in out Map; + Key : in Key_Type; + New_Item : in Element_Type; + Position : out Cursor; + Inserted : out Boolean); + +Insert checks if a node with a key equivalent to Key is already present in Container. If a match is +found, Inserted is set to False and Position designates the element with the matching key. +Otherwise, Insert allocates a new node, initializes it to Key and New_Item, and adds it to +Container; Inserted is set to True and Position designates the newly-inserted node. Any +exception raised during allocation is propagated and Container is not modified. + +procedure Insert (Container : in out Map; + Key : in Key_Type; + Position : out Cursor; + Inserted : out Boolean); + +Insert inserts Key into Container as per the five-parameter Insert, with the difference that an +element initialized by default (see 3.3.1) is inserted. + +procedure Insert (Container : in out Map; + Key : in Key_Type; + New_Item : in Element_Type); + +Insert inserts Key and New_Item into Container as per the five-parameter Insert, with the +difference that if a node with a key equivalent to Key is already in the map, then +Constraint_Error is propagated. + +procedure Include (Container : in out Map; + Key : in Key_Type; + New_Item : in Element_Type); + +Include inserts Key and New_Item into Container as per the five-parameter Insert, with the +difference that if a node with a key equivalent to Key is already in the map, then this operation +assigns Key and New_Item to the matching node. Any exception raised during assignment is +propagated. + +procedure Replace (Container : in out Map; + Key : in Key_Type; + New_Item : in Element_Type); + +Replace checks if a node with a key equivalent to Key is present in Container. If a match is +found, Replace assigns Key and New_Item to the matching node; otherwise, Constraint_Error is +propagated. + +A.18.4 Maps + +13 December 2012 508 + + Ada Reference Manual — 2012 Edition + +procedure Exclude (Container : in out Map; + Key : in Key_Type); + +Exclude checks if a node with a key equivalent to Key is present in Container. If a match is +found, Exclude removes the node from the map. + +procedure Delete (Container : in out Map; + Key : in Key_Type); + +Delete checks if a node with a key equivalent to Key is present in Container. If a match is found, +Delete removes the node from the map; otherwise, Constraint_Error is propagated. + +procedure Delete (Container : in out Map; + Position : in out Cursor); + +If Position equals No_Element, then Constraint_Error is propagated. If Position does not +designate an element in Container, then Program_Error is propagated. Otherwise, Delete +removes the node designated by Position from the map. Position is set to No_Element on return. + +function First (Container : Map) return Cursor; + +If Length (Container) = 0, then First returns No_Element. Otherwise, First returns a cursor that +designates the first node in Container. + +function Next (Position : Cursor) return Cursor; + +Returns a cursor that designates the successor of the node designated by Position. If Position +designates the last node, then No_Element is returned. If Position equals No_Element, then +No_Element is returned. + +procedure Next (Position : in out Cursor); + +Equivalent to Position := Next (Position). + +function Find (Container : Map; + Key : Key_Type) return Cursor; + +If Length (Container) equals 0, then Find returns No_Element. Otherwise, Find checks if a node +with a key equivalent to Key is present in Container. If a match is found, a cursor designating +the matching node is returned; otherwise, No_Element is returned. + +function Element (Container : Map; + Key : Key_Type) return Element_Type; + +Equivalent to Element (Find (Container, Key)). + +function Contains (Container : Map; + Key : Key_Type) return Boolean; + +Equivalent to Find (Container, Key) /= No_Element. + +Paragraphs 72 and 73 were moved above. + +procedure Iterate + (Container : in Map; + Process : not null access procedure (Position : in Cursor)); + +Iterate calls Process.all with a cursor that designates each node in Container, starting with the +first node and moving the cursor according to the successor relation. Tampering with the cursors +of Container is prohibited during the execution of a call on Process.all. Any exception raised by +Process.all is propagated. + +54/2 + +55/2 + +56/2 + +57/2 + +58/2 + +59/2 + +60/2 + +61/2 + +62/2 + +63/2 + +64/2 + +65/2 + +66/2 + +67/2 + +68/2 + +69/2 + +70/2 + +71/2 + +74/2 + +75/3 + +509 13 December 2012 + +Maps A.18.4 + + Ada Reference Manual — 2012 Edition + +75.1/3 + +75.2/3 + +76/2 + +77/2 + +77.1/3 + +Bounded (Run-Time) Errors + +It is a bounded error for the actual function associated with a generic formal subprogram, when called as +part of an operation of a map package, to tamper with elements of any map parameter of the operation. +Either Program_Error is raised, or the operation works as defined on the value of the map either prior to, +or subsequent to, some or all of the modifications to the map. + +It is a bounded error to call any subprogram declared in the visible part of a map package when the +associated container has been finalized. If the operation takes Container as an in out parameter, then it +raises Constraint_Error or Program_Error. Otherwise, the operation either proceeds as it would for an +empty container, or it raises Constraint_Error or Program_Error. + +Erroneous Execution + +A Cursor value is invalid if any of the following have occurred since it was created: + +• The map that contains the node it designates has been finalized; +• The map that contains the node it designates has been used as the Target of a call to Assign, or + +as the target of an assignment_statement; + +78/2 + +• The map that contains the node it designates has been used as the Source or Target of a call to + +Move; or + +79/3 + +80/2 + +• The node it designates has been removed from the map that previously contained the node. + +The result of "=" or Has_Element is unspecified if these functions are called with an invalid cursor +parameter. Execution is erroneous if any other subprogram declared in Containers.Hashed_Maps or +Containers.Ordered_Maps is called with an invalid cursor parameter. + +80.1/3 + +Execution is erroneous if the map associated with the result of a call to Reference or Constant_Reference +is finalized before the result object returned by the call to Reference or Constant_Reference is finalized. + +81/2 + +No storage associated with a Map object shall be lost upon assignment or scope exit. + +Implementation Requirements + +82/3 + +The execution of an assignment_statement for a map shall have the effect of copying the elements from +the source map object to the target map object and changing the length of the target object to that of the +source object. + +83/2 + +Move should not copy elements, and should minimize copying of internal data structures. + +Implementation Advice + +84/2 + +If an exception is propagated from a map operation, no storage should be lost, nor any elements removed +from a map unless specified by the operation. + +A.18.4 Maps + +13 December 2012 510 + + Ada Reference Manual — 2012 Edition + +A.18.5 The Generic Package Containers.Hashed_Maps + +The generic library package Containers.Hashed_Maps has the following declaration: + +Static Semantics + +with Ada.Iterator_Interfaces; +generic + type Key_Type is private; + type Element_Type is private; + with function Hash (Key : Key_Type) return Hash_Type; + with function Equivalent_Keys (Left, Right : Key_Type) + return Boolean; + with function "=" (Left, Right : Element_Type) + return Boolean is <>; +package Ada.Containers.Hashed_Maps is + pragma Preelaborate(Hashed_Maps); + pragma Remote_Types(Hashed_Maps); + type Map is tagged private + with Constant_Indexing => Constant_Reference, + Variable_Indexing => Reference, + Default_Iterator => Iterate, + Iterator_Element => Element_Type; + pragma Preelaborable_Initialization(Map); + type Cursor is private; + pragma Preelaborable_Initialization(Cursor); + Empty_Map : constant Map; + No_Element : constant Cursor; + function Has_Element (Position : Cursor) return Boolean; + package Map_Iterator_Interfaces is new + Ada.Iterator_Interfaces (Cursor, Has_Element); + function "=" (Left, Right : Map) return Boolean; + function Capacity (Container : Map) return Count_Type; + procedure Reserve_Capacity (Container : in out Map; + Capacity : in Count_Type); + function Length (Container : Map) return Count_Type; + function Is_Empty (Container : Map) return Boolean; + procedure Clear (Container : in out Map); + function Key (Position : Cursor) return Key_Type; + function Element (Position : Cursor) return Element_Type; + procedure Replace_Element (Container : in out Map; + Position : in Cursor; + New_Item : in Element_Type); + procedure Query_Element + (Position : in Cursor; + Process : not null access procedure (Key : in Key_Type; + Element : in Element_Type)); + procedure Update_Element + (Container : in out Map; + Position : in Cursor; + Process : not null access procedure + (Key : in Key_Type; + Element : in out Element_Type)); + type Constant_Reference_Type + (Element : not null access constant Element_Type) is private + with Implicit_Dereference => Element; + +1/2 + +2/3 + +3/3 + +4/2 + +5/2 + +6/2 + +6.1/3 + +6.2/3 + +7/2 + +8/2 + +9/2 + +10/2 + +11/2 + +12/2 + +13/2 + +14/2 + +15/2 + +16/2 + +17/2 + +17.1/3 + +511 13 December 2012 + +The Generic Package Containers.Hashed_Maps A.18.5 + + Ada Reference Manual — 2012 Edition + +17.2/3 + +17.3/3 + +17.4/3 + +17.5/3 + +17.6/3 + +17.7/3 + +17.8/3 + +18/2 + +19/2 + +20/2 + +21/2 + +22/2 + +23/2 + +24/2 + +25/2 + +26/2 + +27/2 + +28/2 + +29/2 + +30/2 + +31/2 + +32/2 + +33/3 + + type Reference_Type (Element : not null access Element_Type) is private + with Implicit_Dereference => Element; + function Constant_Reference (Container : aliased in Map; + Position : in Cursor) + return Constant_Reference_Type; + function Reference (Container : aliased in out Map; + Position : in Cursor) + return Reference_Type; + function Constant_Reference (Container : aliased in Map; + Key : in Key_Type) + return Constant_Reference_Type; + function Reference (Container : aliased in out Map; + Key : in Key_Type) + return Reference_Type; + procedure Assign (Target : in out Map; Source : in Map); + function Copy (Source : Map; Capacity : Count_Type := 0) return Map; + procedure Move (Target : in out Map; + Source : in out Map); + procedure Insert (Container : in out Map; + Key : in Key_Type; + New_Item : in Element_Type; + Position : out Cursor; + Inserted : out Boolean); + procedure Insert (Container : in out Map; + Key : in Key_Type; + Position : out Cursor; + Inserted : out Boolean); + procedure Insert (Container : in out Map; + Key : in Key_Type; + New_Item : in Element_Type); + procedure Include (Container : in out Map; + Key : in Key_Type; + New_Item : in Element_Type); + procedure Replace (Container : in out Map; + Key : in Key_Type; + New_Item : in Element_Type); + procedure Exclude (Container : in out Map; + Key : in Key_Type); + procedure Delete (Container : in out Map; + Key : in Key_Type); + procedure Delete (Container : in out Map; + Position : in out Cursor); + function First (Container : Map) + return Cursor; + function Next (Position : Cursor) return Cursor; + procedure Next (Position : in out Cursor); + function Find (Container : Map; + Key : Key_Type) + return Cursor; + function Element (Container : Map; + Key : Key_Type) + return Element_Type; + function Contains (Container : Map; + Key : Key_Type) return Boolean; +This paragraph was deleted. + +A.18.5 The Generic Package Containers.Hashed_Maps + +13 December 2012 512 + + Ada Reference Manual — 2012 Edition + + function Equivalent_Keys (Left, Right : Cursor) + return Boolean; + function Equivalent_Keys (Left : Cursor; + Right : Key_Type) + return Boolean; + function Equivalent_Keys (Left : Key_Type; + Right : Cursor) + return Boolean; + procedure Iterate + (Container : in Map; + Process : not null access procedure (Position : in Cursor)); + function Iterate (Container : in Map) + return Map_Iterator_Interfaces.Forward_Iterator'Class; +private + ... -- not specified by the language +end Ada.Containers.Hashed_Maps; + +An object of type Map contains an expandable hash table, which is used to provide direct access to nodes. +The capacity of an object of type Map is the maximum number of nodes that can be inserted into the hash +table prior to it being automatically expanded. + +Two keys K1 and K2 are defined to be equivalent if Equivalent_Keys (K1, K2) returns True. + +The actual function for the generic formal function Hash is expected to return the same value each time it +is called with a particular key value. For any two equivalent key values, the actual for Hash is expected to +return the same value. If the actual for Hash behaves in some other manner, the behavior of this package is +unspecified. Which subprograms of this package call Hash, and how many times they call it, is +unspecified. + +The actual function for the generic formal function Equivalent_Keys on Key_Type values is expected to +return the same value each time it is called with a particular pair of key values. It should define an +equivalence relationship, that is, be reflexive, symmetric, and transitive. If the actual for Equivalent_Keys +behaves in some other manner, the behavior of this package is unspecified. Which subprograms of this +package call Equivalent_Keys, and how many times they call it, is unspecified. + +If the value of a key stored in a node of a map is changed other than by an operation in this package such +that at least one of Hash or Equivalent_Keys give different results, the behavior of this package is +unspecified. + +Which nodes are the first node and the last node of a map, and which node is the successor of a given +node, are unspecified, other than the general semantics described in A.18.4. + +function Capacity (Container : Map) return Count_Type; + +Returns the capacity of Container. + +procedure Reserve_Capacity (Container : in out Map; + Capacity : in Count_Type); + +Reserve_Capacity allocates a new hash table such that the length of the resulting map can +become at least the value Capacity without requiring an additional call to Reserve_Capacity, and +is large enough to hold the current length of Container. Reserve_Capacity then rehashes the +nodes in Container onto the new hash table. It replaces the old hash table with the new hash +table, and then deallocates the old hash table. Any exception raised during allocation is +propagated and Container is not modified. + +Reserve_Capacity tampers with the cursors of Container. + +513 13 December 2012 + +The Generic Package Containers.Hashed_Maps A.18.5 + +34/2 + +35/2 + +36/2 + +37/2 + +37.1/3 + +38/2 + +39/2 + +40/2 + +41/2 + +42/2 + +43/2 + +44/2 + +45/2 + +46/2 + +47/2 + +48/2 + +49/2 + +50/2 + +51/2 + + 52/2 + +53/2 + +53.1/3 + +53.2/3 + +53.3/3 + +53.4/3 + +54/2 + +55/2 + +56/2 + +57/2 + +58/2 + +59/2 + +60/2 + +61/2 + +61.1/3 + +61.2/3 + +Ada Reference Manual — 2012 Edition + +procedure Clear (Container : in out Map); + +In addition to the semantics described in A.18.4, Clear does not affect the capacity of Container. + +procedure Assign (Target : in out Map; Source : in Map); + +In addition to the semantics described in A.18.4, if the length of Source is greater than the +capacity of Target, Reserve_Capacity (Target, Length (Source)) is called before assigning any +elements. + +function Copy (Source : Map; Capacity : Count_Type := 0) return Map; + +Returns a map whose keys and elements are initialized from the keys and elements of Source. If +Capacity is 0, then the map capacity is the length of Source; if Capacity is equal to or greater +than the length of Source, the map capacity is at least the specified value. Otherwise, the +operation propagates Capacity_Error. + +procedure Insert (Container : in out Map; + Key : in Key_Type; + New_Item : in Element_Type; + Position : out Cursor; + Inserted : out Boolean); + +In addition to the semantics described in A.18.4, if Length (Container) equals Capacity +(Container), then Insert first calls Reserve_Capacity to increase the capacity of Container to +some larger value. + +function Equivalent_Keys (Left, Right : Cursor) + return Boolean; + +Equivalent to Equivalent_Keys (Key (Left), Key (Right)). + +function Equivalent_Keys (Left : Cursor; + Right : Key_Type) return Boolean; + +Equivalent to Equivalent_Keys (Key (Left), Right). + +function Equivalent_Keys (Left : Key_Type; + Right : Cursor) return Boolean; + +Equivalent to Equivalent_Keys (Left, Key (Right)). + +function Iterate (Container : in Map) + return Map_Iterator_Interfaces.Forward_Iterator'Class; + +Iterate returns an iterator object (see 5.5.1) that will generate a value for a loop parameter (see +5.5.2) designating each node in Container, starting with the first node and moving the cursor +according to the successor relation. Tampering with the cursors of Container is prohibited while +the iterator object exists (in particular, in the sequence_of_statements of the loop_statement +whose iterator_specification denotes this object). The iterator object needs finalization. + +62/2 + +If N is the length of a map, the average time complexity of the subprograms Element, Insert, Include, +Replace, Delete, Exclude and Find that take a key parameter should be O(log N). The average time +complexity of the subprograms that take a cursor parameter should be O(1). The average time complexity +of Reserve_Capacity should be O(N). + +Implementation Advice + +A.18.5 The Generic Package Containers.Hashed_Maps + +13 December 2012 514 + + Ada Reference Manual — 2012 Edition + +A.18.6 The Generic Package Containers.Ordered_Maps + +The generic library package Containers.Ordered_Maps has the following declaration: + +Static Semantics + +with Ada.Iterator_Interfaces; +generic + type Key_Type is private; + type Element_Type is private; + with function "<" (Left, Right : Key_Type) return Boolean is <>; + with function "=" (Left, Right : Element_Type) return Boolean is <>; +package Ada.Containers.Ordered_Maps is + pragma Preelaborate(Ordered_Maps); + pragma Remote_Types(Ordered_Maps); + function Equivalent_Keys (Left, Right : Key_Type) return Boolean; + type Map is tagged private + with Constant_Indexing => Constant_Reference, + Variable_Indexing => Reference, + Default_Iterator => Iterate, + Iterator_Element => Element_Type; + pragma Preelaborable_Initialization(Map); + type Cursor is private; + pragma Preelaborable_Initialization(Cursor); + Empty_Map : constant Map; + No_Element : constant Cursor; + function Has_Element (Position : Cursor) return Boolean; + package Map_Iterator_Interfaces is new + Ada.Iterator_Interfaces (Cursor, Has_Element); + function "=" (Left, Right : Map) return Boolean; + function Length (Container : Map) return Count_Type; + function Is_Empty (Container : Map) return Boolean; + procedure Clear (Container : in out Map); + function Key (Position : Cursor) return Key_Type; + function Element (Position : Cursor) return Element_Type; + procedure Replace_Element (Container : in out Map; + Position : in Cursor; + New_Item : in Element_Type); + procedure Query_Element + (Position : in Cursor; + Process : not null access procedure (Key : in Key_Type; + Element : in Element_Type)); + procedure Update_Element + (Container : in out Map; + Position : in Cursor; + Process : not null access procedure + (Key : in Key_Type; + Element : in out Element_Type)); + type Constant_Reference_Type + (Element : not null access constant Element_Type) is private + with Implicit_Dereference => Element; + type Reference_Type (Element : not null access Element_Type) is private + with Implicit_Dereference => Element; + function Constant_Reference (Container : aliased in Map; + Position : in Cursor) + return Constant_Reference_Type; + +1/2 + +2/3 + +3/2 + +4/3 + +5/2 + +6/2 + +7/2 + +7.1/3 + +7.2/3 + +8/2 + +9/2 + +10/2 + +11/2 + +12/2 + +13/2 + +14/2 + +15/2 + +16/2 + +16.1/3 + +16.2/3 + +16.3/3 + +515 13 December 2012 + +The Generic Package Containers.Ordered_Maps A.18.6 + + Ada Reference Manual — 2012 Edition + +16.4/3 + +16.5/3 + +16.6/3 + +16.7/3 + +16.8/3 + +17/2 + +18/2 + +19/2 + +20/2 + +21/2 + +22/2 + +23/2 + +24/2 + +25/2 + +26/2 + +27/2 + +28/2 + +29/2 + +30/2 + +31/2 + +32/2 + +33/2 + +34/2 + +35/2 + +36/2 + +37/2 + +38/2 + +39/2 + + function Reference (Container : aliased in out Map; + Position : in Cursor) + return Reference_Type; + function Constant_Reference (Container : aliased in Map; + Key : in Key_Type) + return Constant_Reference_Type; + function Reference (Container : aliased in out Map; + Key : in Key_Type) + return Reference_Type; + procedure Assign (Target : in out Map; Source : in Map); + function Copy (Source : Map) return Map; + procedure Move (Target : in out Map; + Source : in out Map); + procedure Insert (Container : in out Map; + Key : in Key_Type; + New_Item : in Element_Type; + Position : out Cursor; + Inserted : out Boolean); + procedure Insert (Container : in out Map; + Key : in Key_Type; + Position : out Cursor; + Inserted : out Boolean); + procedure Insert (Container : in out Map; + Key : in Key_Type; + New_Item : in Element_Type); + procedure Include (Container : in out Map; + Key : in Key_Type; + New_Item : in Element_Type); + procedure Replace (Container : in out Map; + Key : in Key_Type; + New_Item : in Element_Type); + procedure Exclude (Container : in out Map; + Key : in Key_Type); + procedure Delete (Container : in out Map; + Key : in Key_Type); + procedure Delete (Container : in out Map; + Position : in out Cursor); + procedure Delete_First (Container : in out Map); + procedure Delete_Last (Container : in out Map); + function First (Container : Map) return Cursor; + function First_Element (Container : Map) return Element_Type; + function First_Key (Container : Map) return Key_Type; + function Last (Container : Map) return Cursor; + function Last_Element (Container : Map) return Element_Type; + function Last_Key (Container : Map) return Key_Type; + function Next (Position : Cursor) return Cursor; + procedure Next (Position : in out Cursor); + function Previous (Position : Cursor) return Cursor; + procedure Previous (Position : in out Cursor); + function Find (Container : Map; + Key : Key_Type) return Cursor; + function Element (Container : Map; + Key : Key_Type) return Element_Type; + +A.18.6 The Generic Package Containers.Ordered_Maps + +13 December 2012 516 + + Ada Reference Manual — 2012 Edition + + function Floor (Container : Map; + Key : Key_Type) return Cursor; + function Ceiling (Container : Map; + Key : Key_Type) return Cursor; + function Contains (Container : Map; + Key : Key_Type) return Boolean; +This paragraph was deleted. + function "<" (Left, Right : Cursor) return Boolean; + function ">" (Left, Right : Cursor) return Boolean; + function "<" (Left : Cursor; Right : Key_Type) return Boolean; + function ">" (Left : Cursor; Right : Key_Type) return Boolean; + function "<" (Left : Key_Type; Right : Cursor) return Boolean; + function ">" (Left : Key_Type; Right : Cursor) return Boolean; + procedure Iterate + (Container : in Map; + Process : not null access procedure (Position : in Cursor)); + procedure Reverse_Iterate + (Container : in Map; + Process : not null access procedure (Position : in Cursor)); + function Iterate (Container : in Map) + return Map_Iterator_Interfaces.Reversible_Iterator'Class; + function Iterate (Container : in Map; Start : in Cursor) + return Map_Iterator_Interfaces.Reversible_Iterator'Class; +private + ... -- not specified by the language +end Ada.Containers.Ordered_Maps; + +Two keys K1 and K2 are equivalent if both K1 < K2 and K2 < K1 return False, using the generic formal +"<" operator for keys. Function Equivalent_Keys returns True if Left and Right are equivalent, and False +otherwise. + +The actual function for the generic formal function "<" on Key_Type values is expected to return the same +value each time it is called with a particular pair of key values. It should define a strict weak ordering +relationship (see A.18). If the actual for "<" behaves in some other manner, the behavior of this package is +unspecified. Which subprograms of this package call "<" and how many times they call it, is unspecified. + +If the value of a key stored in a map is changed other than by an operation in this package such that at least +one of "<" or "=" give different results, the behavior of this package is unspecified. + +The first node of a nonempty map is the one whose key is less than the key of all the other nodes in the +map. The last node of a nonempty map is the one whose key is greater than the key of all the other +elements in the map. The successor of a node is the node with the smallest key that is larger than the key +of the given node. The predecessor of a node is the node with the largest key that is smaller than the key +of the given node. All comparisons are done using the generic formal "<" operator for keys. + +function Copy (Source : Map) return Map; + +Returns a map whose keys and elements are initialized from the corresponding keys and +elements of Source. + +procedure Delete_First (Container : in out Map); + +If Container is empty, Delete_First has no effect. Otherwise, the node designated by First +(Container) is removed from Container. Delete_First tampers with the cursors of Container. + +517 13 December 2012 + +The Generic Package Containers.Ordered_Maps A.18.6 + +40/2 + +41/2 + +42/2 + +43/3 + +44/2 + +45/2 + +46/2 + +47/2 + +48/2 + +49/2 + +50/2 + +51/2 + +51.1/3 + +51.2/3 + +52/2 + +53/2 + +54/2 + +55/2 + +56/3 + +57/2 + +58/3 + +58.1/3 + +58.2/3 + +59/2 + +60/3 + + Ada Reference Manual — 2012 Edition + +61/2 + +62/3 + +63/2 + +64/2 + +65/2 + +66/2 + +67/2 + +68/2 + +69/2 + +70/2 + +71/2 + +72/2 + +73/2 + +74/3 + +75/2 + +76/2 + +77/2 + +78/3 + +79/2 + +80/3 + +81/2 + +82/2 + +83/2 + +84/2 + +85/2 + +86/2 + +procedure Delete_Last (Container : in out Map); + +If Container is empty, Delete_Last has no effect. Otherwise, the node designated by Last +(Container) is removed from Container. Delete_Last tampers with the cursors of Container. + +function First_Element (Container : Map) return Element_Type; + +Equivalent to Element (First (Container)). + +function First_Key (Container : Map) return Key_Type; + +Equivalent to Key (First (Container)). + +function Last (Container : Map) return Cursor; + +Returns a cursor that designates the last node in Container. If Container is empty, returns +No_Element. + +function Last_Element (Container : Map) return Element_Type; + +Equivalent to Element (Last (Container)). + +function Last_Key (Container : Map) return Key_Type; + +Equivalent to Key (Last (Container)). + +function Previous (Position : Cursor) return Cursor; + +If Position equals No_Element, then Previous returns No_Element. Otherwise, Previous returns +a cursor designating the predecessor node of the one designated by Position. If Position +designates the first element, then Previous returns No_Element. + +procedure Previous (Position : in out Cursor); + +Equivalent to Position := Previous (Position). + +function Floor (Container : Map; + Key : Key_Type) return Cursor; + +Floor searches for the last node whose key is not greater than Key, using the generic formal "<" +operator for keys. If such a node is found, a cursor that designates it is returned. Otherwise, +No_Element is returned. + +function Ceiling (Container : Map; + Key : Key_Type) return Cursor; + +Ceiling searches for the first node whose key is not less than Key, using the generic formal "<" +operator for keys. If such a node is found, a cursor that designates it is returned. Otherwise, +No_Element is returned. + +function "<" (Left, Right : Cursor) return Boolean; + +Equivalent to Key (Left) < Key (Right). + +function ">" (Left, Right : Cursor) return Boolean; + +Equivalent to Key (Right) < Key (Left). + +function "<" (Left : Cursor; Right : Key_Type) return Boolean; + +Equivalent to Key (Left) < Right. + +A.18.6 The Generic Package Containers.Ordered_Maps + +13 December 2012 518 + + Ada Reference Manual — 2012 Edition + +function ">" (Left : Cursor; Right : Key_Type) return Boolean; + +Equivalent to Right < Key (Left). + +function "<" (Left : Key_Type; Right : Cursor) return Boolean; + +Equivalent to Left < Key (Right). + +function ">" (Left : Key_Type; Right : Cursor) return Boolean; + +Equivalent to Key (Right) < Left. + +procedure Reverse_Iterate + (Container : in Map; + Process : not null access procedure (Position : in Cursor)); + +Iterates over the nodes in Container as per procedure Iterate, with the difference that the nodes +are traversed in predecessor order, starting with the last node. + +function Iterate (Container : in Map) + return Map_Iterator_Interfaces.Reversible_Iterator'Class; + +Iterate returns a reversible iterator object (see 5.5.1) that will generate a value for a loop +parameter (see 5.5.2) designating each node in Container, starting with the first node and moving +the cursor according to the successor relation when used as a forward iterator, and starting with +the last node and moving the cursor according to the predecessor relation when used as a reverse +iterator. Tampering with the cursors of Container is prohibited while the iterator object exists (in +particular, in the sequence_of_statements of the loop_statement whose iterator_specification +denotes this object). The iterator object needs finalization. + +function Iterate (Container : in Map; Start : in Cursor) + return Map_Iterator_Interfaces.Reversible_Iterator'Class; + +If Start is not No_Element and does not designate an item in Container, then Program_Error is +propagated. If Start is No_Element, then Constraint_Error is propagated. Otherwise, Iterate +returns a reversible iterator object (see 5.5.1) that will generate a value for a loop parameter (see +5.5.2) designating each node in Container, starting with the node designated by Start and moving +the cursor according to the successor relation when used as a forward iterator, or moving the +cursor according to the predecessor relation when used as a reverse iterator. Tampering with the +cursors of Container is prohibited while the iterator object exists (in particular, in the +sequence_of_statements of the loop_statement whose iterator_specification denotes this +object). The iterator object needs finalization. + +87/2 + +88/2 + +89/2 + +90/2 + +91/2 + +92/2 + +93/2 + +94/3 + +94.1/3 + +94.2/3 + +94.3/3 + +94.4/3 + +If N is the length of a map, then the worst-case time complexity of the Element, Insert, Include, Replace, +Delete, Exclude and Find operations that take a key parameter should be O((log N)**2) or better. The +worst-case time complexity of the subprograms that take a cursor parameter should be O(1). + +95/2 + +Implementation Advice + +A.18.7 Sets + +The language-defined generic packages Containers.Hashed_Sets and Containers.Ordered_Sets provide +private types Set and Cursor, and a set of operations for each type. A set container allows elements of an +arbitrary type to be stored without duplication. A hashed set uses a hash function to organize elements, +while an ordered set orders its element per a specified relation. + +1/2 + +519 13 December 2012 + +The Generic Package Containers.Ordered_Maps A.18.6 + + Ada Reference Manual — 2012 Edition + +2/3 + +3/2 + +4/2 + +5/2 + +6/2 + +7/2 + +8/2 + +9/2 + +10/2 + +10.1/3 + +11/2 + +12/2 + +13/2 + +14/2 + +14.1/3 + +15/2 + +16/2 + +This subclause describes the declarations that are common to both kinds of sets. See A.18.8 for a +description of the semantics specific to Containers.Hashed_Sets and A.18.9 for a description of the +semantics specific to Containers.Ordered_Sets. + +Static Semantics + +The actual function for the generic formal function "=" on Element_Type values is expected to define a +reflexive and symmetric relationship and return the same result value each time it is called with a +particular pair of values. If it behaves in some other manner, the function "=" on set values returns an +unspecified value. The exact arguments and number of calls of this generic formal function by the function +"=" on set values are unspecified. + +The type Set is used to represent sets. The type Set needs finalization (see 7.6). + +A set contains elements. Set cursors designate elements. There exists an equivalence relation on elements, +whose definition is different for hashed sets and ordered sets. A set never contains two or more equivalent +elements. The length of a set is the number of elements it contains. + +Each nonempty set has two particular elements called the first element and the last element (which may be +the same). Each element except for the last element has a successor element. If there are no other +intervening operations, starting with the first element and repeatedly going to the successor element will +visit each element in the set exactly once until the last element is reached. The exact definition of these +terms is different for hashed sets and ordered sets. + +Some operations of these generic packages have access-to-subprogram parameters. To ensure such +operations are well-defined, they guard against certain actions by the designated subprogram. In particular, +some operations check for “tampering with cursors” of a container because they depend on the set of +elements of the container remaining constant, and others check for “tampering with elements” of a +container because they depend on elements of the container not being replaced. + +A subprogram is said to tamper with cursors of a set object S if: + +• + +• +• +• +• + +it inserts or deletes elements of S, that is, it calls the Insert, Include, Clear, Delete, Exclude, or +Replace_Element procedures with S as a parameter; or + +it finalizes S; or + +it calls the Assign procedure with S as the Target parameter; or + +it calls the Move procedure with S as a parameter; or + +it calls one of the operations defined to tamper with cursors of S. + +A subprogram is said to tamper with elements of a set object S if: + +• + +it tampers with cursors of S. + +When tampering with cursors is prohibited for a particular set object S, Program_Error is propagated by a +call of any language-defined subprogram that is defined to tamper with the cursors of S, leaving S +unmodified. Similarly, when tampering with elements is prohibited for a particular set object S, +Program_Error is propagated by a call of any language-defined subprogram that is defined to tamper with +the elements of S (or tamper with the cursors of S), leaving S unmodified. + +Empty_Set represents the empty Set object. It has a length of 0. If an object of type Set is not otherwise +initialized, it is initialized to the same value as Empty_Set. + +No_Element represents a cursor that designates no element. If an object of type Cursor is not otherwise +initialized, it is initialized to the same value as No_Element. + +A.18.7 Sets + +13 December 2012 520 + + Ada Reference Manual — 2012 Edition + +The predefined "=" operator for type Cursor returns True if both cursors are No_Element, or designate the +same element in the same container. + +Execution of the default implementation of the Input, Output, Read, or Write attribute of type Cursor +raises Program_Error. + +17/2 + +18/2 + +Set'Write for a Set object S writes Length(S) elements of the set to the stream. It also may write additional +information about the set. + +18.1/3 + +Set'Read reads the representation of a set from the stream, and assigns to Item a set with the same length +and elements as was written by Set'Write. + +function Has_Element (Position : Cursor) return Boolean; + +Returns True if Position designates an element, and returns False otherwise. + +function "=" (Left, Right : Set) return Boolean; + +If Left and Right denote the same set object, then the function returns True. If Left and Right +have different lengths, then the function returns False. Otherwise, for each element E in Left, the +function returns False if an element equal to E (using the generic formal equality operator) is not +present in Right. If the function has not returned a result after checking all of the elements, it +returns True. Any exception raised during evaluation of element equality is propagated. + +function Equivalent_Sets (Left, Right : Set) return Boolean; + +If Left and Right denote the same set object, then the function returns True. If Left and Right +have different lengths, then the function returns False. Otherwise, for each element E in Left, the +function returns False if an element equivalent to E is not present in Right. If the function has +not returned a result after checking all of the elements, it returns True. Any exception raised +during evaluation of element equivalence is propagated. + +function To_Set (New_Item : Element_Type) return Set; + +Returns a set containing the single element New_Item. + +function Length (Container : Set) return Count_Type; + +Returns the number of elements in Container. + +function Is_Empty (Container : Set) return Boolean; + +Equivalent to Length (Container) = 0. + +procedure Clear (Container : in out Set); + +Removes all the elements from Container. + +function Element (Position : Cursor) return Element_Type; + +If Position equals No_Element, then Constraint_Error is propagated. Otherwise, Element returns +the element designated by Position. + +procedure Replace_Element (Container : in out Set; + Position : in Cursor; + New_Item : in Element_Type); + +If Position equals No_Element, then Constraint_Error is propagated; if Position does not +designate an element in Container, then Program_Error is propagated. If an element equivalent +to New_Item is already present in Container at a position other than Position, Program_Error is + +521 13 December 2012 + +Sets A.18.7 + +18.2/3 + +18.3/3 + +18.4/3 + +19/2 + +20/2 + +21/2 + +22/2 + +23/2 + +24/2 + +25/2 + +26/2 + +27/2 + +28/2 + +29/2 + +30/2 + +31/2 + +32/2 + +33/2 + +34/2 + + Ada Reference Manual — 2012 Edition + +propagated. Otherwise, Replace_Element assigns New_Item to the element designated by +Position. Any exception raised by the assignment is propagated. + +procedure Query_Element + (Position : in Cursor; + Process : not null access procedure (Element : in Element_Type)); + +If Position equals No_Element, then Constraint_Error is propagated. Otherwise, Query_Element +calls Process.all with the element designated by Position as the argument. Tampering with the +elements of the set that contains the element designated by Position is prohibited during the +execution of the call on Process.all. Any exception raised by Process.all is propagated. + +type Constant_Reference_Type + (Element : not null access constant Element_Type) is private + with Implicit_Dereference => Element; + +The type Constant_Reference_Type needs finalization. + +The default +Program_Error. + +initialization of an object of + +type Constant_Reference_Type propagates + +function Constant_Reference (Container : aliased in Set; + Position : in Cursor) + return Constant_Reference_Type; + +This function (combined with the Constant_Indexing and Implicit_Dereference aspects) provides +a convenient way to gain read access to an individual element of a set given a cursor. + +If Position equals No_Element, then Constraint_Error is propagated; if Position does not +designate an element +is propagated. Otherwise, +Constant_Reference returns an object whose discriminant is an access value that designates the +element designated by Position. Tampering with the elements of Container is prohibited while +the object returned by Constant_Reference exists and has not been finalized. + +then Program_Error + +in Container, + +procedure Assign (Target : in out Set; Source : in Set); + +If Target denotes the same object as Source, the operation has no effect. Otherwise, the elements +of Source are copied to Target as for an assignment_statement assigning Source to Target. + +procedure Move (Target : in out Set; + Source : in out Set); + +If Target denotes the same object as Source, then the operation has no effect. Otherwise, the +operation is equivalent to Assign (Target, Source) followed by Clear (Source). + +procedure Insert (Container : in out Set; + New_Item : in Element_Type; + Position : out Cursor; + Inserted : out Boolean); + +Insert checks if an element equivalent to New_Item is already present in Container. If a match is +found, Inserted is set to False and Position designates the matching element. Otherwise, Insert +adds New_Item to Container; Inserted is set to True and Position designates the newly-inserted +element. Any exception raised during allocation is propagated and Container is not modified. + +procedure Insert (Container : in out Set; + New_Item : in Element_Type); + +Insert inserts New_Item into Container as per the four-parameter Insert, with the difference that +if an element equivalent to New_Item is already in the set, then Constraint_Error is propagated. + +A.18.7 Sets + +13 December 2012 522 + +35/2 + +36/3 + +36.1/3 + +36.2/3 + +36.3/3 + +36.4/3 + +36.5/3 + +36.6/3 + +36.7/3 + +36.8/3 + +37/2 + +38/3 + +39/2 + +40/2 + +41/2 + +42/2 + + Ada Reference Manual — 2012 Edition + +procedure Include (Container : in out Set; + New_Item : in Element_Type); + +Include inserts New_Item into Container as per the four-parameter Insert, with the difference +that if an element equivalent to New_Item is already in the set, then it is replaced. Any exception +raised during assignment is propagated. + +procedure Replace (Container : in out Set; + New_Item : in Element_Type); + +Replace checks if an element equivalent to New_Item is already in the set. If a match is found, +that element is replaced with New_Item; otherwise, Constraint_Error is propagated. + +procedure Exclude (Container : in out Set; + Item : in Element_Type); + +Exclude checks if an element equivalent to Item is present in Container. If a match is found, +Exclude removes the element from the set. + +procedure Delete (Container : in out Set; + Item : in Element_Type); + +Delete checks if an element equivalent to Item is present in Container. If a match is found, +Delete removes the element from the set; otherwise, Constraint_Error is propagated. + +procedure Delete (Container : in out Set; + Position : in out Cursor); + +If Position equals No_Element, then Constraint_Error is propagated. If Position does not +designate an element in Container, then Program_Error is propagated. Otherwise, Delete +removes the element designated by Position from the set. Position is set to No_Element on +return. + +procedure Union (Target : in out Set; + Source : in Set); + +Union inserts into Target the elements of Source that are not equivalent to some element already +in Target. + +function Union (Left, Right : Set) return Set; + +Returns a set comprising all of the elements of Left, and the elements of Right that are not +equivalent to some element of Left. + +procedure Intersection (Target : in out Set; + Source : in Set); + +Intersection deletes from Target the elements of Target that are not equivalent to some element +of Source. + +function Intersection (Left, Right : Set) return Set; + +Returns a set comprising all the elements of Left that are equivalent to the some element of +Right. + +procedure Difference (Target : in out Set; + Source : in Set); + +If Target denotes the same object as Source, then Difference clears Target. Otherwise, it deletes +from Target the elements that are equivalent to some element of Source. + +43/2 + +44/2 + +45/2 + +46/2 + +47/2 + +48/2 + +49/2 + +50/2 + +51/2 + +52/2 + +53/2 + +54/2 + +55/2 + +56/2 + +57/2 + +58/3 + +59/2 + +60/2 + +61/2 + +62/2 + +523 13 December 2012 + +Sets A.18.7 + + Ada Reference Manual — 2012 Edition + +63/2 + +64/2 + +65/2 + +66/2 + +67/2 + +68/2 + +69/2 + +70/3 + +71/2 + +72/3 + +73/2 + +74/2 + +75/2 + +76/2 + +77/2 + +78/2 + +79/3 + +80/2 + +81/2 + +82/2 + +82.1/3 + +function Difference (Left, Right : Set) return Set; + +Returns a set comprising the elements of Left that are not equivalent to some element of Right. + +procedure Symmetric_Difference (Target : in out Set; + Source : in Set); + +If Target denotes the same object as Source, then Symmetric_Difference clears Target. +Otherwise, it deletes from Target the elements that are equivalent to some element of Source, +and inserts into Target the elements of Source that are not equivalent to some element of Target. + +function Symmetric_Difference (Left, Right : Set) return Set; + +Returns a set comprising the elements of Left that are not equivalent to some element of Right, +and the elements of Right that are not equivalent to some element of Left. + +function Overlap (Left, Right : Set) return Boolean; + +If an element of Left is equivalent to some element of Right, then Overlap returns True. +Otherwise, it returns False. + +function Is_Subset (Subset : Set; + Of_Set : Set) return Boolean; + +If an element of Subset is not equivalent to some element of Of_Set, then Is_Subset returns +False. Otherwise, it returns True. + +function First (Container : Set) return Cursor; + +If Length (Container) = 0, then First returns No_Element. Otherwise, First returns a cursor that +designates the first element in Container. + +function Next (Position : Cursor) return Cursor; + +Returns a cursor that designates the successor of the element designated by Position. If Position +designates the last element, then No_Element is returned. If Position equals No_Element, then +No_Element is returned. + +procedure Next (Position : in out Cursor); + +Equivalent to Position := Next (Position). + +This paragraph was deleted. + +function Find (Container : Set; + Item : Element_Type) return Cursor; + +If Length (Container) equals 0, then Find returns No_Element. Otherwise, Find checks if an +element equivalent to Item is present in Container. If a match is found, a cursor designating the +matching element is returned; otherwise, No_Element is returned. + +function Contains (Container : Set; + Item : Element_Type) return Boolean; + +Equivalent to Find (Container, Item) /= No_Element. + +Paragraphs 83 and 84 were moved above. + +A.18.7 Sets + +13 December 2012 524 + + Ada Reference Manual — 2012 Edition + +procedure Iterate + (Container : in Set; + Process : not null access procedure (Position : in Cursor)); + +Iterate calls Process.all with a cursor that designates each element in Container, starting with the +first element and moving the cursor according to the successor relation. Tampering with the +cursors of Container is prohibited during the execution of a call on Process.all. Any exception +raised by Process.all is propagated. + +Both Containers.Hashed_Set and Containers.Ordered_Set declare a nested generic package Generic_Keys, +which provides operations that allow set manipulation in terms of a key (typically, a portion of an element) +instead of a complete element. The formal function Key of Generic_Keys extracts a key value from an +element. It is expected to return the same value each time it is called with a particular element. The +behavior of Generic_Keys is unspecified if Key behaves in some other manner. + +A key is expected to unambiguously determine a single equivalence class for elements. The behavior of +Generic_Keys is unspecified if the formal parameters of this package behave in some other manner. + +function Key (Position : Cursor) return Key_Type; + +Equivalent to Key (Element (Position)). + +The subprograms in package Generic_Keys named Contains, Find, Element, Delete, and Exclude, are +equivalent to the corresponding subprograms in the parent package, with the difference that the Key +parameter is used to locate an element in the set. + +procedure Replace (Container : in out Set; + Key : in Key_Type; + New_Item : in Element_Type); + +Equivalent to Replace_Element (Container, Find (Container, Key), New_Item). + +procedure Update_Element_Preserving_Key + (Container : in out Set; + Position : in Cursor; + Process : not null access procedure + (Element : in out Element_Type)); + +If Position equals No_Element, then Constraint_Error is propagated; if Position does not +designate an element in Container, then Program_Error is propagated. Otherwise, Update_- +Element_Preserving_Key uses Key to save the key value K of the element designated by +Position. Update_Element_Preserving_Key then calls Process.all with that element as the +argument. Tampering with the elements of Container is prohibited during the execution of the +call on Process.all. Any exception raised by Process.all is propagated. After Process.all returns, +Update_Element_Preserving_Key checks if K determines the same equivalence class as that for +the new element; if not, the element is removed from the set and Program_Error is propagated. + +85/2 + +86/3 + +87/2 + +88/2 + +89/2 + +90/2 + +91/2 + +92/2 + +93/2 + +94/2 + +95/3 + +If Element_Type is unconstrained and definite, then the actual Element parameter of Process.all +shall be unconstrained. + +96/2 + +type Reference_Type (Element : not null access Element_Type) is private + with Implicit_Dereference => Element; + +The type Reference_Type needs finalization. + +The default initialization of an object of type Reference_Type propagates Program_Error. + +96.1/3 + +96.2/3 + +96.3/3 + +525 13 December 2012 + +Sets A.18.7 + + Ada Reference Manual — 2012 Edition + +function Reference_Preserving_Key (Container : aliased in out Set; + Position : in Cursor) + return Reference_Type; + +This function (combined with the Implicit_Dereference aspect) provides a convenient way to +gain read and write access to an individual element of a set given a cursor. + +in Container, + +then Program_Error + +If Position equals No_Element, then Constraint_Error is propagated; if Position does not +designate an element +is propagated. Otherwise, +Reference_Preserving_Key uses Key to save the key value K; then returns an object whose +discriminant is an access value that designates the element designated by Position. Tampering +with +returned by +Reference_Preserving_Key exists and has not been finalized. When the object returned by +Reference_Preserving_Key is finalized, a check is made if K determines the same equivalence +class as that for the new element; if not, the element is removed from the set and Program_Error +is propagated. + +elements of Container + +is prohibited while + +the object + +the + +function Constant_Reference (Container : aliased in Set; + Key : in Key_Type) + return Constant_Reference_Type; + +This function (combined with the Implicit_Dereference aspect) provides a convenient way to +gain read access to an individual element of a set given a key value. + +Equivalent to Constant_Reference (Container, Find (Container, Key)). + +function Reference_Preserving_Key (Container : aliased in out Set; + Key : in Key_Type) + return Reference_Type; + +This function (combined with the Implicit_Dereference aspect) provides a convenient way to +gain read and write access to an individual element of a set given a key value. + +96.4/3 + +96.5/3 + +96.6/3 + +96.7/3 + +96.8/3 + +96.9/3 + +96.10/3 + +96.11/3 + +96.12/3 + +Equivalent to Reference_Preserving_Key (Container, Find (Container, Key)). + +96.13/3 + +96.14/3 + +97/2 + +98/2 + +98.1/3 + +Bounded (Run-Time) Errors + +It is a bounded error for the actual function associated with a generic formal subprogram, when called as +part of an operation of a set package, to tamper with elements of any set parameter of the operation. Either +Program_Error is raised, or the operation works as defined on the value of the set either prior to, or +subsequent to, some or all of the modifications to the set. + +It is a bounded error to call any subprogram declared in the visible part of a set package when the +associated container has been finalized. If the operation takes Container as an in out parameter, then it +raises Constraint_Error or Program_Error. Otherwise, the operation either proceeds as it would for an +empty container, or it raises Constraint_Error or Program_Error. + +Erroneous Execution + +A Cursor value is invalid if any of the following have occurred since it was created: + +• The set that contains the element it designates has been finalized; +• The set that contains the element it designates has been used as the Target of a call to Assign, or + +as the target of an assignment_statement; + +99/2 + +• The set that contains the element it designates has been used as the Source or Target of a call to + +Move; or + +100/3 + +• The element it designates has been removed from the set that previously contained the element. + +A.18.7 Sets + +13 December 2012 526 + + Ada Reference Manual — 2012 Edition + +The result of "=" or Has_Element is unspecified if these functions are called with an invalid cursor +parameter. Execution is erroneous if any other subprogram declared in Containers.Hashed_Sets or +Containers.Ordered_Sets is called with an invalid cursor parameter. + +101/2 + +Execution is erroneous if the set associated with the result of a call to Reference or Constant_Reference is +finalized before the result object returned by the call to Reference or Constant_Reference is finalized. + +101.1/3 + +No storage associated with a Set object shall be lost upon assignment or scope exit. + +Implementation Requirements + +The execution of an assignment_statement for a set shall have the effect of copying the elements from +the source set object to the target set object and changing the length of the target object to that of the +source object. + +Move should not copy elements, and should minimize copying of internal data structures. + +Implementation Advice + +If an exception is propagated from a set operation, no storage should be lost, nor any elements removed +from a set unless specified by the operation. + +A.18.8 The Generic Package Containers.Hashed_Sets + +The generic library package Containers.Hashed_Sets has the following declaration: + +Static Semantics + +with Ada.Iterator_Interfaces; +generic + type Element_Type is private; + with function Hash (Element : Element_Type) return Hash_Type; + with function Equivalent_Elements (Left, Right : Element_Type) + return Boolean; + with function "=" (Left, Right : Element_Type) return Boolean is <>; +package Ada.Containers.Hashed_Sets is + pragma Preelaborate(Hashed_Sets); + pragma Remote_Types(Hashed_Sets); + type Set is tagged private + with Constant_Indexing => Constant_Reference, + Default_Iterator => Iterate, + Iterator_Element => Element_Type; + pragma Preelaborable_Initialization(Set); + type Cursor is private; + pragma Preelaborable_Initialization(Cursor); + Empty_Set : constant Set; + No_Element : constant Cursor; + function Has_Element (Position : Cursor) return Boolean; + package Set_Iterator_Interfaces is new + Ada.Iterator_Interfaces (Cursor, Has_Element); + function "=" (Left, Right : Set) return Boolean; + function Equivalent_Sets (Left, Right : Set) return Boolean; + function To_Set (New_Item : Element_Type) return Set; + function Capacity (Container : Set) return Count_Type; + procedure Reserve_Capacity (Container : in out Set; + Capacity : in Count_Type); + +102/2 + +103/3 + +104/2 + +105/2 + +1/2 + +2/3 + +3/3 + +4/2 + +5/2 + +6/2 + +6.1/3 + +6.2/3 + +7/2 + +8/2 + +9/2 + +10/2 + +11/2 + +527 13 December 2012 + +Sets A.18.7 + + Ada Reference Manual — 2012 Edition + +12/2 + +13/2 + +14/2 + +15/2 + +16/2 + +17/2 + +17.1/3 + +17.2/3 + +17.3/3 + +17.4/3 + +18/2 + +19/2 + +20/2 + +21/2 + +22/2 + +23/2 + +24/2 + +25/2 + +26/2 + +27/2 + +28/2 + +29/2 + +30/2 + +31/2 + +32/2 + +33/2 + +34/2 + +35/2 + +36/2 + +37/2 + + function Length (Container : Set) return Count_Type; + function Is_Empty (Container : Set) return Boolean; + procedure Clear (Container : in out Set); + function Element (Position : Cursor) return Element_Type; + procedure Replace_Element (Container : in out Set; + Position : in Cursor; + New_Item : in Element_Type); + procedure Query_Element + (Position : in Cursor; + Process : not null access procedure (Element : in Element_Type)); + type Constant_Reference_Type + (Element : not null access constant Element_Type) is private + with Implicit_Dereference => Element; + function Constant_Reference (Container : aliased in Set; + Position : in Cursor) + return Constant_Reference_Type; + procedure Assign (Target : in out Set; Source : in Set); + function Copy (Source : Set; Capacity : Count_Type := 0) return Set; + procedure Move (Target : in out Set; + Source : in out Set); + procedure Insert (Container : in out Set; + New_Item : in Element_Type; + Position : out Cursor; + Inserted : out Boolean); + procedure Insert (Container : in out Set; + New_Item : in Element_Type); + procedure Include (Container : in out Set; + New_Item : in Element_Type); + procedure Replace (Container : in out Set; + New_Item : in Element_Type); + procedure Exclude (Container : in out Set; + Item : in Element_Type); + procedure Delete (Container : in out Set; + Item : in Element_Type); + procedure Delete (Container : in out Set; + Position : in out Cursor); + procedure Union (Target : in out Set; + Source : in Set); + function Union (Left, Right : Set) return Set; + function "or" (Left, Right : Set) return Set renames Union; + procedure Intersection (Target : in out Set; + Source : in Set); + function Intersection (Left, Right : Set) return Set; + function "and" (Left, Right : Set) return Set renames Intersection; + procedure Difference (Target : in out Set; + Source : in Set); + function Difference (Left, Right : Set) return Set; + function "-" (Left, Right : Set) return Set renames Difference; + procedure Symmetric_Difference (Target : in out Set; + Source : in Set); + function Symmetric_Difference (Left, Right : Set) return Set; + function "xor" (Left, Right : Set) return Set + renames Symmetric_Difference; + +A.18.8 The Generic Package Containers.Hashed_Sets + +13 December 2012 528 + + Ada Reference Manual — 2012 Edition + + function Overlap (Left, Right : Set) return Boolean; + function Is_Subset (Subset : Set; + Of_Set : Set) return Boolean; + function First (Container : Set) return Cursor; + function Next (Position : Cursor) return Cursor; + procedure Next (Position : in out Cursor); + function Find (Container : Set; + Item : Element_Type) return Cursor; + function Contains (Container : Set; + Item : Element_Type) return Boolean; +This paragraph was deleted. + function Equivalent_Elements (Left, Right : Cursor) + return Boolean; + function Equivalent_Elements (Left : Cursor; + Right : Element_Type) + return Boolean; + function Equivalent_Elements (Left : Element_Type; + Right : Cursor) + return Boolean; + procedure Iterate + (Container : in Set; + Process : not null access procedure (Position : in Cursor)); + function Iterate (Container : in Set) + return Set_Iterator_Interfaces.Forward_Iterator'Class; + generic + type Key_Type (<>) is private; + with function Key (Element : Element_Type) return Key_Type; + with function Hash (Key : Key_Type) return Hash_Type; + with function Equivalent_Keys (Left, Right : Key_Type) + return Boolean; + package Generic_Keys is + function Key (Position : Cursor) return Key_Type; + function Element (Container : Set; + Key : Key_Type) + return Element_Type; + procedure Replace (Container : in out Set; + Key : in Key_Type; + New_Item : in Element_Type); + procedure Exclude (Container : in out Set; + Key : in Key_Type); + procedure Delete (Container : in out Set; + Key : in Key_Type); + function Find (Container : Set; + Key : Key_Type) + return Cursor; + function Contains (Container : Set; + Key : Key_Type) + return Boolean; + procedure Update_Element_Preserving_Key + (Container : in out Set; + Position : in Cursor; + Process : not null access procedure + (Element : in out Element_Type)); + type Reference_Type + (Element : not null access Element_Type) is private + with Implicit_Dereference => Element; + +38/2 + +39/2 + +40/2 + +41/2 + +42/2 + +43/2 + +44/2 + +45/3 + +46/2 + +47/2 + +48/2 + +49/2 + +49.1/3 + +50/2 + +51/2 + +52/2 + +53/2 + +54/2 + +55/2 + +56/2 + +57/2 + +58/2 + +58.1/3 + +529 13 December 2012 + +The Generic Package Containers.Hashed_Sets A.18.8 + + Ada Reference Manual — 2012 Edition + +58.2/3 + +58.3/3 + +58.4/3 + +59/2 + +60/2 + +61/2 + +62/2 + +63/2 + + function Reference_Preserving_Key (Container : aliased in out Set; + Position : in Cursor) + return Reference_Type; + function Constant_Reference (Container : aliased in Set; + Key : in Key_Type) + return Constant_Reference_Type; + function Reference_Preserving_Key (Container : aliased in out Set; + Key : in Key_Type) + return Reference_Type; + end Generic_Keys; +private + ... -- not specified by the language +end Ada.Containers.Hashed_Sets; + +An object of type Set contains an expandable hash table, which is used to provide direct access to +elements. The capacity of an object of type Set is the maximum number of elements that can be inserted +into the hash table prior to it being automatically expanded. + +64/2 + +Two elements E1 and E2 are defined to be equivalent if Equivalent_Elements (E1, E2) returns True. + +65/2 + +66/2 + +The actual function for the generic formal function Hash is expected to return the same value each time it +is called with a particular element value. For any two equivalent elements, the actual for Hash is expected +to return the same value. If the actual for Hash behaves in some other manner, the behavior of this package +is unspecified. Which subprograms of this package call Hash, and how many times they call it, is +unspecified. + +The actual function for the generic formal function Equivalent_Elements is expected to return the same +value each time it is called with a particular pair of Element values. It should define an equivalence +relationship, that is, be reflexive, symmetric, and transitive. If the actual for Equivalent_Elements behaves +in some other manner, the behavior of this package is unspecified. Which subprograms of this package call +Equivalent_Elements, and how many times they call it, is unspecified. + +66.1/3 + +If the actual function for the generic formal function "=" returns True for any pair of nonequivalent +elements, then the behavior of the container function "=" is unspecified. + +67/2 + +68/2 + +69/2 + +70/2 + +71/2 + +72/2 + +If the value of an element stored in a set is changed other than by an operation in this package such that at +least one of Hash or Equivalent_Elements give different results, the behavior of this package is +unspecified. + +Which elements are the first element and the last element of a set, and which element is the successor of a +given element, are unspecified, other than the general semantics described in A.18.7. + +function Capacity (Container : Set) return Count_Type; + +Returns the capacity of Container. + +procedure Reserve_Capacity (Container : in out Set; + Capacity : in Count_Type); + +Reserve_Capacity allocates a new hash table such that the length of the resulting set can become +at least the value Capacity without requiring an additional call to Reserve_Capacity, and is large +enough to hold the current length of Container. Reserve_Capacity then rehashes the elements in +Container onto the new hash table. It replaces the old hash table with the new hash table, and +then deallocates the old hash table. Any exception raised during allocation is propagated and +Container is not modified. + +73/2 + +Reserve_Capacity tampers with the cursors of Container. + +A.18.8 The Generic Package Containers.Hashed_Sets + +13 December 2012 530 + + Ada Reference Manual — 2012 Edition + +procedure Clear (Container : in out Set); + +In addition to the semantics described in A.18.7, Clear does not affect the capacity of Container. + +procedure Assign (Target : in out Set; Source : in Set); + +In addition to the semantics described in A.18.7, if the length of Source is greater than the +capacity of Target, Reserve_Capacity (Target, Length (Source)) is called before assigning any +elements. + +function Copy (Source : Set; Capacity : Count_Type := 0) return Set; + +Returns a set whose elements are initialized from the elements of Source. If Capacity is 0, then +the set capacity is the length of Source; if Capacity is equal to or greater than the length of +Source, the set capacity is at least the specified value. Otherwise, the operation propagates +Capacity_Error. + +procedure Insert (Container : in out Set; + New_Item : in Element_Type; + Position : out Cursor; + Inserted : out Boolean); + +In addition to the semantics described in A.18.7, if Length (Container) equals Capacity +(Container), then Insert first calls Reserve_Capacity to increase the capacity of Container to +some larger value. + +function First (Container : Set) return Cursor; + +If Length (Container) = 0, then First returns No_Element. Otherwise, First returns a cursor that +designates the first hashed element in Container. + +function Equivalent_Elements (Left, Right : Cursor) + return Boolean; + +Equivalent to Equivalent_Elements (Element (Left), Element (Right)). + +function Equivalent_Elements (Left : Cursor; + Right : Element_Type) return Boolean; + +Equivalent to Equivalent_Elements (Element (Left), Right). + +function Equivalent_Elements (Left : Element_Type; + Right : Cursor) return Boolean; + +Equivalent to Equivalent_Elements (Left, Element (Right)). + +function Iterate (Container : in Set) + return Set_Iterator_Interfaces.Forward_Iterator'Class; + +Iterate returns an iterator object (see 5.5.1) that will generate a value for a loop parameter (see +5.5.2) designating each element in Container, starting with the first element and moving the +cursor according to the successor relation. Tampering with the cursors of Container is prohibited +while the iterator object exists (in particular, in the sequence_of_statements of the +loop_statement whose iterator_specification denotes this object). The iterator object needs +finalization. + +74/2 + +75/2 + +75.1/3 + +75.2/3 + +75.3/3 + +75.4/3 + +76/2 + +77/2 + +78/2 + +79/2 + +80/2 + +81/2 + +82/2 + +83/2 + +84/2 + +85/2 + +85.1/3 + +85.2/3 + +For any element E, the actual function for the generic formal function Generic_Keys.Hash is expected to +be such that Hash (E) = Generic_Keys.Hash (Key (E)). If the actuals for Key or Generic_Keys.Hash +behave in some other manner, the behavior of Generic_Keys is unspecified. Which subprograms of +Generic_Keys call Generic_Keys.Hash, and how many times they call it, is unspecified. + +86/2 + +531 13 December 2012 + +The Generic Package Containers.Hashed_Sets A.18.8 + + Ada Reference Manual — 2012 Edition + +For any two elements E1 and E2, the boolean values Equivalent_Elements (E1, E2) and Equivalent_Keys +(Key (E1), Key (E2)) are expected to be equal. If the actuals for Key or Equivalent_Keys behave in some +other manner, the behavior of Generic_Keys is unspecified. Which subprograms of Generic_Keys call +Equivalent_Keys, and how many times they call it, is unspecified. + +Implementation Advice + +If N is the length of a set, the average time complexity of the subprograms Insert, Include, Replace, Delete, +Exclude and Find that take an element parameter should be O(log N). The average time complexity of the +subprograms that take a cursor parameter should be O(1). The average time complexity of +Reserve_Capacity should be O(N). + +A.18.9 The Generic Package Containers.Ordered_Sets + +The generic library package Containers.Ordered_Sets has the following declaration: + +Static Semantics + +with Ada.Iterator_Interfaces; +generic + type Element_Type is private; + with function "<" (Left, Right : Element_Type) return Boolean is <>; + with function "=" (Left, Right : Element_Type) return Boolean is <>; +package Ada.Containers.Ordered_Sets is + pragma Preelaborate(Ordered_Sets); + pragma Remote_Types(Ordered_Sets); + function Equivalent_Elements (Left, Right : Element_Type) return Boolean; + type Set is tagged private + with Constant_Indexing => Constant_Reference, + Default_Iterator => Iterate, + Iterator_Element => Element_Type; + pragma Preelaborable_Initialization(Set); + type Cursor is private; + pragma Preelaborable_Initialization(Cursor); + Empty_Set : constant Set; + No_Element : constant Cursor; + function Has_Element (Position : Cursor) return Boolean; + package Set_Iterator_Interfaces is new + Ada.Iterator_Interfaces (Cursor, Has_Element); + function "=" (Left, Right : Set) return Boolean; + function Equivalent_Sets (Left, Right : Set) return Boolean; + function To_Set (New_Item : Element_Type) return Set; + function Length (Container : Set) return Count_Type; + function Is_Empty (Container : Set) return Boolean; + procedure Clear (Container : in out Set); + function Element (Position : Cursor) return Element_Type; + procedure Replace_Element (Container : in out Set; + Position : in Cursor; + New_Item : in Element_Type); + procedure Query_Element + (Position : in Cursor; + Process : not null access procedure (Element : in Element_Type)); + type Constant_Reference_Type + (Element : not null access constant Element_Type) is private + with Implicit_Dereference => Element; + +87/2 + +88/2 + +1/2 + +2/3 + +3/2 + +4/3 + +5/2 + +6/2 + +7/2 + +7.1/3 + +7.2/3 + +8/2 + +9/2 + +10/2 + +11/2 + +12/2 + +13/2 + +14/2 + +15/2 + +16/2 + +16.1/3 + +A.18.8 The Generic Package Containers.Hashed_Sets + +13 December 2012 532 + + Ada Reference Manual — 2012 Edition + + function Constant_Reference (Container : aliased in Set; + Position : in Cursor) + return Constant_Reference_Type; + procedure Assign (Target : in out Set; Source : in Set); + function Copy (Source : Set) return Set; + procedure Move (Target : in out Set; + Source : in out Set); + procedure Insert (Container : in out Set; + New_Item : in Element_Type; + Position : out Cursor; + Inserted : out Boolean); + procedure Insert (Container : in out Set; + New_Item : in Element_Type); + procedure Include (Container : in out Set; + New_Item : in Element_Type); + procedure Replace (Container : in out Set; + New_Item : in Element_Type); + procedure Exclude (Container : in out Set; + Item : in Element_Type); + procedure Delete (Container : in out Set; + Item : in Element_Type); + procedure Delete (Container : in out Set; + Position : in out Cursor); + procedure Delete_First (Container : in out Set); + procedure Delete_Last (Container : in out Set); + procedure Union (Target : in out Set; + Source : in Set); + function Union (Left, Right : Set) return Set; + function "or" (Left, Right : Set) return Set renames Union; + procedure Intersection (Target : in out Set; + Source : in Set); + function Intersection (Left, Right : Set) return Set; + function "and" (Left, Right : Set) return Set renames Intersection; + procedure Difference (Target : in out Set; + Source : in Set); + function Difference (Left, Right : Set) return Set; + function "-" (Left, Right : Set) return Set renames Difference; + procedure Symmetric_Difference (Target : in out Set; + Source : in Set); + function Symmetric_Difference (Left, Right : Set) return Set; + function "xor" (Left, Right : Set) return Set renames + Symmetric_Difference; + function Overlap (Left, Right : Set) return Boolean; + function Is_Subset (Subset : Set; + Of_Set : Set) return Boolean; + function First (Container : Set) return Cursor; + function First_Element (Container : Set) return Element_Type; + function Last (Container : Set) return Cursor; + function Last_Element (Container : Set) return Element_Type; + function Next (Position : Cursor) return Cursor; + procedure Next (Position : in out Cursor); + +16.2/3 + +16.3/3 + +16.4/3 + +17/2 + +18/2 + +19/2 + +20/2 + +21/2 + +22/2 + +23/2 + +24/2 + +25/2 + +26/2 + +27/2 + +28/2 + +29/2 + +30/2 + +31/2 + +32/2 + +33/2 + +34/2 + +35/2 + +36/2 + +37/2 + +38/2 + +39/2 + +40/2 + +41/2 + +42/2 + +43/2 + +44/2 + +45/2 + +46/2 + +533 13 December 2012 + +The Generic Package Containers.Ordered_Sets A.18.9 + + Ada Reference Manual — 2012 Edition + +47/2 + +48/2 + +49/2 + +50/2 + +51/2 + +52/2 + +53/3 + +54/2 + +55/2 + +56/2 + +57/2 + +58/2 + +59/2 + +60/2 + +61/2 + +61.1/3 + +61.2/3 + +62/2 + +63/2 + +64/2 + +65/2 + +66/2 + +67/2 + +68/2 + + function Previous (Position : Cursor) return Cursor; + procedure Previous (Position : in out Cursor); + function Find (Container : Set; + Item : Element_Type) + return Cursor; + function Floor (Container : Set; + Item : Element_Type) + return Cursor; + function Ceiling (Container : Set; + Item : Element_Type) + return Cursor; + function Contains (Container : Set; + Item : Element_Type) return Boolean; +This paragraph was deleted. + function "<" (Left, Right : Cursor) return Boolean; + function ">" (Left, Right : Cursor) return Boolean; + function "<" (Left : Cursor; Right : Element_Type) + return Boolean; + function ">" (Left : Cursor; Right : Element_Type) + return Boolean; + function "<" (Left : Element_Type; Right : Cursor) + return Boolean; + function ">" (Left : Element_Type; Right : Cursor) + return Boolean; + procedure Iterate + (Container : in Set; + Process : not null access procedure (Position : in Cursor)); + procedure Reverse_Iterate + (Container : in Set; + Process : not null access procedure (Position : in Cursor)); + function Iterate (Container : in Set) + return Set_Iterator_Interfaces.Reversible_Iterator'Class; + function Iterate (Container : in Set; Start : in Cursor) + return Set_Iterator_Interfaces.Reversible_Iterator'Class; + generic + type Key_Type (<>) is private; + with function Key (Element : Element_Type) return Key_Type; + with function "<" (Left, Right : Key_Type) + return Boolean is <>; + package Generic_Keys is + function Equivalent_Keys (Left, Right : Key_Type) + return Boolean; + function Key (Position : Cursor) return Key_Type; + function Element (Container : Set; + Key : Key_Type) + return Element_Type; + procedure Replace (Container : in out Set; + Key : in Key_Type; + New_Item : in Element_Type); + procedure Exclude (Container : in out Set; + Key : in Key_Type); + procedure Delete (Container : in out Set; + Key : in Key_Type); + +A.18.9 The Generic Package Containers.Ordered_Sets + +13 December 2012 534 + + Ada Reference Manual — 2012 Edition + + function Find (Container : Set; + Key : Key_Type) + return Cursor; + function Floor (Container : Set; + Key : Key_Type) + return Cursor; + function Ceiling (Container : Set; + Key : Key_Type) + return Cursor; + function Contains (Container : Set; + Key : Key_Type) return Boolean; + procedure Update_Element_Preserving_Key + (Container : in out Set; + Position : in Cursor; + Process : not null access procedure + (Element : in out Element_Type)); + type Reference_Type + (Element : not null access Element_Type) is private + with Implicit_Dereference => Element; + function Reference_Preserving_Key (Container : aliased in out Set; + Position : in Cursor) + return Reference_Type; + function Constant_Reference (Container : aliased in Set; + Key : in Key_Type) + return Constant_Reference_Type; + function Reference_Preserving_Key (Container : aliased in out Set; + Key : in Key_Type) + return Reference_Type; + end Generic_Keys; +private + ... -- not specified by the language +end Ada.Containers.Ordered_Sets; + +Two elements E1 and E2 are equivalent if both E1 < E2 and E2 < E1 return False, using the generic formal +"<" operator for elements. Function Equivalent_Elements returns True if Left and Right are equivalent, +and False otherwise. + +The actual function for the generic formal function "<" on Element_Type values is expected to return the +same value each time it is called with a particular pair of key values. It should define a strict weak +ordering relationship (see A.18). If the actual for "<" behaves in some other manner, the behavior of this +package is unspecified. Which subprograms of this package call "<" and how many times they call it, is +unspecified. + +69/2 + +70/2 + +71/2 + +72/2 + +73/2 + +73.1/3 + +73.2/3 + +73.3/3 + +73.4/3 + +74/2 + +75/2 + +76/2 + +77/2 + +78/2 + +79/3 + +If the actual function for the generic formal function "=" returns True for any pair of nonequivalent +elements, then the behavior of the container function "=" is unspecified. + +79.1/3 + +If the value of an element stored in a set is changed other than by an operation in this package such that at +least one of "<" or "=" give different results, the behavior of this package is unspecified. + +The first element of a nonempty set is the one which is less than all the other elements in the set. The last +element of a nonempty set is the one which is greater than all the other elements in the set. The successor +of an element is the smallest element that is larger than the given element. The predecessor of an element +is the largest element that is smaller than the given element. All comparisons are done using the generic +formal "<" operator for elements. + +80/2 + +81/3 + +535 13 December 2012 + +The Generic Package Containers.Ordered_Sets A.18.9 + + Ada Reference Manual — 2012 Edition + +81.1/3 + +81.2/3 + +82/2 + +83/3 + +84/2 + +85/3 + +86/2 + +87/2 + +88/2 + +89/2 + +90/2 + +91/2 + +92/2 + +93/3 + +94/2 + +95/2 + +96/2 + +97/3 + +98/2 + +99/3 + +100/2 + +101/2 + +102/2 + +103/2 + +104/2 + +105/2 + +106/2 + +107/2 + +function Copy (Source : Set) return Set; + +Returns a set whose elements are initialized from the corresponding elements of Source. + +procedure Delete_First (Container : in out Set); + +If Container is empty, Delete_First has no effect. Otherwise, the element designated by First +(Container) is removed from Container. Delete_First tampers with the cursors of Container. + +procedure Delete_Last (Container : in out Set); + +If Container is empty, Delete_Last has no effect. Otherwise, the element designated by Last +(Container) is removed from Container. Delete_Last tampers with the cursors of Container. + +function First_Element (Container : Set) return Element_Type; + +Equivalent to Element (First (Container)). + +function Last (Container : Set) return Cursor; + +Returns a cursor that designates the last element in Container. If Container is empty, returns +No_Element. + +function Last_Element (Container : Set) return Element_Type; + +Equivalent to Element (Last (Container)). + +function Previous (Position : Cursor) return Cursor; + +If Position equals No_Element, then Previous returns No_Element. Otherwise, Previous returns +a cursor designating the predecessor element of the one designated by Position. If Position +designates the first element, then Previous returns No_Element. + +procedure Previous (Position : in out Cursor); + +Equivalent to Position := Previous (Position). + +function Floor (Container : Set; + Item : Element_Type) return Cursor; + +Floor searches for the last element which is not greater than Item. If such an element is found, a +cursor that designates it is returned. Otherwise, No_Element is returned. + +function Ceiling (Container : Set; + Item : Element_Type) return Cursor; + +Ceiling searches for the first element which is not less than Item. If such an element is found, a +cursor that designates it is returned. Otherwise, No_Element is returned. + +function "<" (Left, Right : Cursor) return Boolean; + +Equivalent to Element (Left) < Element (Right). + +function ">" (Left, Right : Cursor) return Boolean; + +Equivalent to Element (Right) < Element (Left). + +function "<" (Left : Cursor; Right : Element_Type) return Boolean; + +Equivalent to Element (Left) < Right. + +function ">" (Left : Cursor; Right : Element_Type) return Boolean; + +Equivalent to Right < Element (Left). + +A.18.9 The Generic Package Containers.Ordered_Sets + +13 December 2012 536 + + Ada Reference Manual — 2012 Edition + +function "<" (Left : Element_Type; Right : Cursor) return Boolean; + +Equivalent to Left < Element (Right). + +function ">" (Left : Element_Type; Right : Cursor) return Boolean; + +Equivalent to Element (Right) < Left. + +procedure Reverse_Iterate + (Container : in Set; + Process : not null access procedure (Position : in Cursor)); + +108/2 + +109/2 + +110/2 + +111/2 + +112/2 + +Iterates over the elements in Container as per procedure Iterate, with the difference that the +elements are traversed in predecessor order, starting with the last element. + +113/3 + +function Iterate (Container : in Set) + return Set_Iterator_Interfaces.Reversible_Iterator'Class; + +Iterate returns a reversible iterator object (see 5.5.1) that will generate a value for a loop +parameter (see 5.5.2) designating each element in Container, starting with the first element and +moving the cursor according to the successor relation when used as a forward iterator, and +starting with the last element and moving the cursor according to the predecessor relation when +used as a reverse iterator. Tampering with the cursors of Container is prohibited while the +iterator object exists (in particular, in the sequence_of_statements of the loop_statement +whose iterator_specification denotes this object). The iterator object needs finalization. + +function Iterate (Container : in Set; Start : in Cursor) + return Set_Iterator_Interfaces.Reversible_Iterator'Class; + +If Start is not No_Element and does not designate an item in Container, then Program_Error is +propagated. If Start is No_Element, then Constraint_Error is propagated. Otherwise, Iterate +returns a reversible iterator object (see 5.5.1) that will generate a value for a loop parameter (see +5.5.2) designating each element in Container, starting with the element designated by Start and +moving the cursor according to the successor relation when used as a forward iterator, or moving +the cursor according to the predecessor relation when used as a reverse iterator. Tampering with +the cursors of Container is prohibited while the iterator object exists (in particular, in the +sequence_of_statements of the loop_statement whose iterator_specification denotes this +object). The iterator object needs finalization. + +For any two elements E1 and E2, the boolean values (E1 < E2) and (Key(E1) < Key(E2)) are expected to +be equal. If the actuals for Key or Generic_Keys."<" behave in some other manner, the behavior of this +package is unspecified. Which subprograms of this package call Key and Generic_Keys."<", and how +many times the functions are called, is unspecified. + +In addition to the semantics described in A.18.7, the subprograms in package Generic_Keys named Floor +and Ceiling, are equivalent to the corresponding subprograms in the parent package, with the difference +that the Key subprogram parameter is compared to elements in the container using the Key and "<" +generic formal functions. The function named Equivalent_Keys in package Generic_Keys returns True if +both Left < Right and Right < Left return False using the generic formal "<" operator, and returns True +otherwise. + +113.1/3 + +113.2/3 + +113.3/3 + +113.4/3 + +114/2 + +115/2 + +If N is the length of a set, then the worst-case time complexity of the Insert, Include, Replace, Delete, +Exclude and Find operations that take an element parameter should be O((log N)**2) or better. The worst- +case time complexity of the subprograms that take a cursor parameter should be O(1). + +116/2 + +Implementation Advice + +537 13 December 2012 + +The Generic Package Containers.Ordered_Sets A.18.9 + + Ada Reference Manual — 2012 Edition + +A.18.10 The Generic Package Containers.Multiway_Trees + +The language-defined generic package Containers.Multiway_Trees provides private types Tree and +Cursor, and a set of operations for each type. A multiway tree container is well-suited to represent nested +structures. + +A multiway tree container object manages a tree of internal nodes, each of which contains an element and +pointers to the parent, first child, last child, next (successor) sibling, and previous (predecessor) sibling +internal nodes. A cursor designates a particular node within a tree (and by extension the element contained +in that node, if any). A cursor keeps designating the same node (and element) as long as the node is part of +the container, even if the node is moved within the container. + +A subtree is a particular node (which roots the subtree) and all of its child nodes (including all of the +children of the child nodes, recursively). There is a special node, the root, which is always present and has +neither an associated element value nor any parent node. The root node provides a place to add nodes to an +otherwise empty tree and represents the base of the tree. + +A node that has no children is called a leaf node. The ancestors of a node are the node itself, its parent +node, the parent of the parent node, and so on until a node with no parent is reached. Similarly, the +descendants of a node are the node itself, its child nodes, the children of each child node, and so on. + +The nodes of a subtree can be visited in several different orders. For a depth-first order, after visiting a +node, the nodes of its child list are each visited in depth-first order, with each child node visited in natural +order (first child to last child). + +The generic library package Containers.Multiway_Trees has the following declaration: + +Static Semantics + +with Ada.Iterator_Interfaces; +generic + type Element_Type is private; + with function "=" (Left, Right : Element_Type) return Boolean is <>; +package Ada.Containers.Multiway_Trees is + pragma Preelaborate(Multiway_Trees); + pragma Remote_Types(Multiway_Trees); + type Tree is tagged private + with Constant_Indexing => Constant_Reference, + Variable_Indexing => Reference, + Default_Iterator => Iterate, + Iterator_Element => Element_Type; + pragma Preelaborable_Initialization(Tree); + type Cursor is private; + pragma Preelaborable_Initialization(Cursor); + Empty_Tree : constant Tree; + No_Element : constant Cursor; + function Has_Element (Position : Cursor) return Boolean; + package Tree_Iterator_Interfaces is new + Ada.Iterator_Interfaces (Cursor, Has_Element); + function Equal_Subtree (Left_Position : Cursor; + Right_Position: Cursor) return Boolean; + function "=" (Left, Right : Tree) return Boolean; + function Is_Empty (Container : Tree) return Boolean; + function Node_Count (Container : Tree) return Count_Type; + +1/3 + +2/3 + +3/3 + +4/3 + +5/3 + +6/3 + +7/3 + +8/3 + +9/3 + +10/3 + +11/3 + +12/3 + +13/3 + +14/3 + +15/3 + +16/3 + +17/3 + +A.18.10 The Generic Package Containers.Multiway_Trees + +13 December 2012 538 + + Ada Reference Manual — 2012 Edition + + function Subtree_Node_Count (Position : Cursor) return Count_Type; + function Depth (Position : Cursor) return Count_Type; + function Is_Root (Position : Cursor) return Boolean; + function Is_Leaf (Position : Cursor) return Boolean; + function Root (Container : Tree) return Cursor; + procedure Clear (Container : in out Tree); + function Element (Position : Cursor) return Element_Type; + procedure Replace_Element (Container : in out Tree; + Position : in Cursor; + New_Item : in Element_Type); + procedure Query_Element + (Position : in Cursor; + Process : not null access procedure (Element : in Element_Type)); + procedure Update_Element + (Container : in out Tree; + Position : in Cursor; + Process : not null access procedure + (Element : in out Element_Type)); + type Constant_Reference_Type + (Element : not null access constant Element_Type) is private + with Implicit_Dereference => Element; + type Reference_Type (Element : not null access Element_Type) is private + with Implicit_Dereference => Element; + function Constant_Reference (Container : aliased in Tree; + Position : in Cursor) + return Constant_Reference_Type; + function Reference (Container : aliased in out Tree; + Position : in Cursor) + return Reference_Type; + procedure Assign (Target : in out Tree; Source : in Tree); + function Copy (Source : Tree) return Tree; + procedure Move (Target : in out Tree; + Source : in out Tree); + procedure Delete_Leaf (Container : in out Tree; + Position : in out Cursor); + procedure Delete_Subtree (Container : in out Tree; + Position : in out Cursor); + procedure Swap (Container : in out Tree; + I, J : in Cursor); + function Find (Container : Tree; + Item : Element_Type) + return Cursor; + function Find_In_Subtree (Position : Cursor; + Item : Element_Type) + return Cursor; + function Ancestor_Find (Position : Cursor; + Item : Element_Type) + return Cursor; + function Contains (Container : Tree; + Item : Element_Type) return Boolean; + procedure Iterate + (Container : in Tree; + Process : not null access procedure (Position : in Cursor)); + +18/3 + +19/3 + +20/3 + +21/3 + +22/3 + +23/3 + +24/3 + +25/3 + +26/3 + +27/3 + +28/3 + +29/3 + +30/3 + +31/3 + +32/3 + +33/3 + +34/3 + +35/3 + +36/3 + +37/3 + +38/3 + +39/3 + +40/3 + +41/3 + +42/3 + +539 13 December 2012 + +The Generic Package Containers.Multiway_Trees A.18.10 + + Ada Reference Manual — 2012 Edition + +43/3 + +44/3 + +45/3 + +46/3 + +47/3 + +48/3 + +49/3 + +50/3 + +51/3 + +52/3 + +53/3 + +54/3 + +55/3 + +56/3 + +57/3 + +58/3 + +59/3 + + procedure Iterate_Subtree + (Position : in Cursor; + Process : not null access procedure (Position : in Cursor)); + function Iterate (Container : in Tree) + return Tree_Iterator_Interfaces.Forward_Iterator'Class; + function Iterate_Subtree (Position : in Cursor) + return Tree_Iterator_Interfaces.Forward_Iterator'Class; + function Child_Count (Parent : Cursor) return Count_Type; + function Child_Depth (Parent, Child : Cursor) return Count_Type; + procedure Insert_Child (Container : in out Tree; + Parent : in Cursor; + Before : in Cursor; + New_Item : in Element_Type; + Count : in Count_Type := 1); + procedure Insert_Child (Container : in out Tree; + Parent : in Cursor; + Before : in Cursor; + New_Item : in Element_Type; + Position : out Cursor; + Count : in Count_Type := 1); + procedure Insert_Child (Container : in out Tree; + Parent : in Cursor; + Before : in Cursor; + Position : out Cursor; + Count : in Count_Type := 1); + procedure Prepend_Child (Container : in out Tree; + Parent : in Cursor; + New_Item : in Element_Type; + Count : in Count_Type := 1); + procedure Append_Child (Container : in out Tree; + Parent : in Cursor; + New_Item : in Element_Type; + Count : in Count_Type := 1); + procedure Delete_Children (Container : in out Tree; + Parent : in Cursor); + procedure Copy_Subtree (Target : in out Tree; + Parent : in Cursor; + Before : in Cursor; + Source : in Cursor); + procedure Splice_Subtree (Target : in out Tree; + Parent : in Cursor; + Before : in Cursor; + Source : in out Tree; + Position : in out Cursor); + procedure Splice_Subtree (Container: in out Tree; + Parent : in Cursor; + Before : in Cursor; + Position : in Cursor); + procedure Splice_Children (Target : in out Tree; + Target_Parent : in Cursor; + Before : in Cursor; + Source : in out Tree; + Source_Parent : in Cursor); + procedure Splice_Children (Container : in out Tree; + Target_Parent : in Cursor; + Before : in Cursor; + Source_Parent : in Cursor); + function Parent (Position : Cursor) return Cursor; + +A.18.10 The Generic Package Containers.Multiway_Trees + +13 December 2012 540 + + Ada Reference Manual — 2012 Edition + + function First_Child (Parent : Cursor) return Cursor; + function First_Child_Element (Parent : Cursor) return Element_Type; + function Last_Child (Parent : Cursor) return Cursor; + function Last_Child_Element (Parent : Cursor) return Element_Type; + function Next_Sibling (Position : Cursor) return Cursor; + function Previous_Sibling (Position : Cursor) return Cursor; + procedure Next_Sibling (Position : in out Cursor); + procedure Previous_Sibling (Position : in out Cursor); + procedure Iterate_Children + (Parent : in Cursor; + Process : not null access procedure (Position : in Cursor)); + procedure Reverse_Iterate_Children + (Parent : in Cursor; + Process : not null access procedure (Position : in Cursor)); + function Iterate_Children (Container : in Tree; Parent : in Cursor) + return Tree_Iterator_Interfaces.Reversible_Iterator'Class; +private + ... -- not specified by the language +end Ada.Containers.Multiway_Trees; + +The actual function for the generic formal function "=" on Element_Type values is expected to define a +reflexive and symmetric relationship and return the same result value each time it is called with a +particular pair of values. If it behaves in some other manner, the functions Find, Reverse_Find, +Equal_Subtree, and "=" on tree values return an unspecified value. The exact arguments and number of +calls of this generic formal function by the functions Find, Reverse_Find, Equal_Subtree, and "=" on tree +values are unspecified. + +The type Tree is used to represent trees. The type Tree needs finalization (see 7.6). + +Empty_Tree represents the empty Tree object. It contains only the root node (Node_Count (Empty_Tree) +returns 1). If an object of type Tree is not otherwise initialized, it is initialized to the same value as +Empty_Tree. + +No_Element represents a cursor that designates no element. If an object of type Cursor is not otherwise +initialized, it is initialized to the same value as No_Element. + +The predefined "=" operator for type Cursor returns True if both cursors are No_Element, or designate the +same element in the same container. + +Execution of the default implementation of the Input, Output, Read, or Write attribute of type Cursor +raises Program_Error. + +Tree'Write for a Tree object T writes Node_Count(T) - 1 elements of the tree to the stream. It also may +write additional information about the tree. + +Tree'Read reads the representation of a tree from the stream, and assigns to Item a tree with the same +elements and structure as was written by Tree'Write. + +Some operations of this generic package have access-to-subprogram parameters. To ensure such +operations are well-defined, they guard against certain actions by the designated subprogram. In particular, +some operations check for "tampering with cursors" of a container because they depend on the set of +elements of the container remaining constant, and others check for "tampering with elements" of a +container because they depend on elements of the container not being replaced. + +A subprogram is said to tamper with cursors of a tree object T if: + +541 13 December 2012 + +The Generic Package Containers.Multiway_Trees A.18.10 + +60/3 + +61/3 + +62/3 + +63/3 + +64/3 + +65/3 + +66/3 + +67/3 + +68/3 + +69/3 + +70/3 + +71/3 + +72/3 + +73/3 + +74/3 + +75/3 + +76/3 + +77/3 + +78/3 + +79/3 + +80/3 + +81/3 + + Ada Reference Manual — 2012 Edition + +82/3 + +83/3 + +84/3 + +85/3 + +86/3 + +87/3 + +88/3 + +89/3 + +90/3 + +91/3 + +92/3 + +93/3 + +94/3 + +95/3 + +96/3 + +97/3 + +98/3 + +99/3 + +100/3 + +• + +• + +• +• +• + +it inserts or deletes elements of T, that is, it calls the Clear, Delete_Leaf, Insert_Child, +Delete_Children, Delete_Subtree, or Copy_Subtree procedures with T as a parameter; or + +it reorders the elements of T, that is, it calls the Splice_Subtree or Splice_Children procedures +with T as a parameter; or + +it finalizes T; or + +it calls Assign with T as the Target parameter; or + +it calls the Move procedure with T as a parameter. + +A subprogram is said to tamper with elements of a tree object T if: + +• +• + +it tampers with cursors of T; or + +it replaces one or more elements of T, that is, it calls the Replace_Element or Swap procedures +with T as a parameter. + +When tampering with cursors is prohibited for a particular tree object T, Program_Error is propagated by a +call of any language-defined subprogram that is defined to tamper with the cursors of T, leaving T +unmodified. Similarly, when tampering with elements is prohibited for a particular tree object T, +Program_Error is propagated by a call of any language-defined subprogram that is defined to tamper with +the elements of T (or tamper with the cursors of T), leaving T unmodified. + +function Has_Element (Position : Cursor) return Boolean; + +Returns True if Position designates an element, and returns False otherwise. In particular, +Has_Element returns False if the cursor designates a root node or equals No_Element. + +function Equal_Subtree (Left_Position : Cursor; + Right_Position: Cursor) return Boolean; + +If Left_Position or Right_Position equals No_Element, propagates Constraint_Error. If the +number of child nodes of the element designated by Left_Position is different from the number +of child nodes of the element designated by Right_Position, the function returns False. If +Left_Position designates a root node and Right_Position does not, the function returns False. If +Right_Position designates a root node and Left_Position does not, the function returns False. +Unless both cursors designate a root node, the elements are compared using the generic formal +equality operator. If the result of the element comparison is False, the function returns False. +Otherwise, it calls Equal_Subtree on a cursor designating each child element of the element +designated by Left_Position and a cursor designating the corresponding child element of the +element designated by Right_Position. If any such call returns False, the function returns False; +otherwise, it returns True. Any exception raised during the evaluation of element equality is +propagated. + +function "=" (Left, Right : Tree) return Boolean; + +If Left and Right denote the same tree object, then the function returns True. Otherwise, it calls +Equal_Subtree with cursors designating the root nodes of Left and Right; the result is returned. +Any exception raised during the evaluation of Equal_Subtree is propagated. + +function Node_Count (Container : Tree) return Count_Type; + +Node_Count returns the number of nodes in Container. + +function Subtree_Node_Count (Position : Cursor) return Count_Type; + +If Position is No_Element, Subtree_Node_Count returns 0; otherwise, Subtree_Node_Count +returns the number of nodes in the subtree that is rooted by Position. + +A.18.10 The Generic Package Containers.Multiway_Trees + +13 December 2012 542 + + Ada Reference Manual — 2012 Edition + +function Is_Empty (Container : Tree) return Boolean; + +Equivalent to Node_Count (Container) = 1. + +function Depth (Position : Cursor) return Count_Type; + +If Position equals No_Element, Depth returns 0; otherwise, Depth returns the number of ancestor +nodes of the node designated by Position (including the node itself). + +function Is_Root (Position : Cursor) return Boolean; + +Is_Root returns True if the Position designates the root node of some tree; and returns False +otherwise. + +function Is_Leaf (Position : Cursor) return Boolean; + +Is_Leaf returns True if Position designates a node that does not have any child nodes; and +returns False otherwise. + +function Root (Container : Tree) return Cursor; + +Root returns a cursor that designates the root node of Container. + +procedure Clear (Container : in out Tree); + +Removes all the elements from Container. + +function Element (Position : Cursor) return Element_Type; + +If Position equals No_Element, then Constraint_Error is propagated; if Position designates the +root node of a tree, then Program_Error is propagated. Otherwise, Element returns the element +designated by Position. + +procedure Replace_Element (Container : in out Tree; + Position : in Cursor; + New_Item : in Element_Type); + +If Position equals No_Element, then Constraint_Error is propagated; if Position does not +designate an element in Container (including if it designates the root node), then Program_Error +is propagated. Otherwise, Replace_Element assigns the value New_Item to the element +designated by Position. + +procedure Query_Element + (Position : in Cursor; + Process : not null access procedure (Element : in Element_Type)); + +If Position equals No_Element, then Constraint_Error is propagated; if Position designates the +root node of a tree, then Program_Error is propagated. Otherwise, Query_Element calls +Process.all with the element designated by Position as the argument. Tampering with the +elements of the tree that contains the element designated by Position is prohibited during the +execution of the call on Process.all. Any exception raised by Process.all is propagated. + +procedure Update_Element + (Container : in out Tree; + Position : in Cursor; + Process : not null access procedure + (Element : in out Element_Type)); + +101/3 + +102/3 + +103/3 + +104/3 + +105/3 + +106/3 + +107/3 + +108/3 + +109/3 + +110/3 + +111/3 + +112/3 + +113/3 + +114/3 + +115/3 + +116/3 + +117/3 + +118/3 + +119/3 + +If Position equals No_Element, then Constraint_Error is propagated; if Position does not +designate an element in Container (including if it designates the root node), then Program_Error +is propagated. Otherwise, Update_Element calls Process.all with the element designated by + +120/3 + +543 13 December 2012 + +The Generic Package Containers.Multiway_Trees A.18.10 + + 121/3 + +122/3 + +123/3 + +124/3 + +125/3 + +126/3 + +127/3 + +128/3 + +129/3 + +130/3 + +131/3 + +132/3 + +133/3 + +134/3 + +135/3 + +136/3 + +137/3 + +Ada Reference Manual — 2012 Edition + +Position as the argument. Tampering with the elements of Container is prohibited during the +execution of the call on Process.all. Any exception raised by Process.all is propagated. + +If Element_Type is unconstrained and definite, then the actual Element parameter of Process.all +shall be unconstrained. + +type Constant_Reference_Type + (Element : not null access constant Element_Type) is private + with Implicit_Dereference => Element; +type Reference_Type (Element : not null access Element_Type) is private + with Implicit_Dereference => Element; + +The types Constant_Reference_Type and Reference_Type need finalization. + +The default initialization of an object of type Constant_Reference_Type or Reference_Type +propagates Program_Error. + +function Constant_Reference (Container : aliased in Tree; + Position : in Cursor) + return Constant_Reference_Type; + +This function (combined with the Constant_Indexing and Implicit_Dereference aspects) provides +a convenient way to gain read access to an individual element of a tree given a cursor. + +If Position equals No_Element, then Constraint_Error is propagated; if Position does not +is propagated. Otherwise, +designate an element +Constant_Reference returns an object whose discriminant is an access value that designates the +element designated by Position. Tampering with the elements of Container is prohibited while +the object returned by Constant_Reference exists and has not been finalized. + +then Program_Error + +in Container, + +function Reference (Container : aliased in out Tree; + Position : in Cursor) + return Reference_Type; + +This function (combined with the Variable_Indexing and Implicit_Dereference aspects) provides +a convenient way to gain read and write access to an individual element of a tree given a cursor. + +If Position equals No_Element, then Constraint_Error is propagated; if Position does not +designate an element in Container, then Program_Error is propagated. Otherwise, Reference +returns an object whose discriminant is an access value that designates the element designated +by Position. Tampering with the elements of Container is prohibited while the object returned by +Reference exists and has not been finalized. + +procedure Assign (Target : in out Tree; Source : in Tree); + +If Target denotes the same object as Source, the operation has no effect. Otherwise, the elements +of Source are copied to Target as for an assignment_statement assigning Source to Target. + +function Copy (Source : Tree) return Tree; + +Returns a tree with the same structure as Source and whose elements are initialized from the +corresponding elements of Source. + +procedure Move (Target : in out Tree; + Source : in out Tree); + +If Target denotes the same object as Source, then the operation has no effect. Otherwise, Move +first calls Clear (Target). Then, the nodes other than the root node in Source are moved to Target + +A.18.10 The Generic Package Containers.Multiway_Trees + +13 December 2012 544 + + Ada Reference Manual — 2012 Edition + +(in the same positions). After Move completes, Node_Count (Target) is the number of nodes +originally in Source, and Node_Count (Source) is 1. + +procedure Delete_Leaf (Container : in out Tree; + Position : in out Cursor); + +If Position equals No_Element, then Constraint_Error is propagated; if Position does not +designate an element in Container (including if it designates the root node), then Program_Error +then +is propagated. If +Constraint_Error is propagated. Otherwise, Delete_Leaf removes (from Container) the element +designated by Position. Finally, Position is set to No_Element. + +the element designated by position has any child elements, + +procedure Delete_Subtree (Container : in out Tree; + Position : in out Cursor); + +If Position equals No_Element, then Constraint_Error is propagated. If Position does not +designate an element in Container (including if it designates the root node), then Program_Error +is propagated. Otherwise, Delete_Subtree removes (from Container) the subtree designated by +Position (that is, all descendants of the node designated by Position including the node itself), +and Position is set to No_Element. + +procedure Swap (Container : in out Tree; + I, J : in Cursor); + +If either I or J equals No_Element, then Constraint_Error is propagated. If either I or J do not +designate an element in Container (including if either designates the root node), then +Program_Error is propagated. Otherwise, Swap exchanges the values of the elements designated +by I and J. + +function Find (Container : Tree; + Item : Element_Type) + return Cursor; + +Find searches the elements of Container for an element equal to Item (using the generic formal +equality operator). The search starts at the root node. The search traverses the tree in a depth- +first order. If no equal element is found, then Find returns No_Element. Otherwise, it returns a +cursor designating the first equal element encountered. + +function Find_In_Subtree (Position : Cursor; + Item : Element_Type) + return Cursor; + +If Position equals No_Element, then Constraint_Error is propagated. Find_In_Subtree searches +the subtree rooted by Position for an element equal to Item (using the generic formal equality +operator). The search starts at the element designated by Position. The search traverses the +subtree in a depth-first order. If no equal element is found, then Find returns No_Element. +Otherwise, it returns a cursor designating the first equal element encountered. + +function Ancestor_Find (Position : Cursor; + Item : Element_Type) + return Cursor; + +If Position equals No_Element, then Constraint_Error is propagated. Otherwise, Ancestor_Find +searches for an element equal to Item (using the generic formal equality operator). The search +starts at the node designated by Position, and checks each ancestor proceeding toward the root of +the subtree. If no equal element is found, then Ancestor_Find returns No_Element. Otherwise, it +returns a cursor designating the first equal element encountered. + +138/3 + +139/3 + +140/3 + +141/3 + +142/3 + +143/3 + +144/3 + +145/3 + +146/3 + +147/3 + +148/3 + +149/3 + +545 13 December 2012 + +The Generic Package Containers.Multiway_Trees A.18.10 + + 150/3 + +151/3 + +152/3 + +153/3 + +154/3 + +155/3 + +156/3 + +157/3 + +158/3 + +159/3 + +160/3 + +161/3 + +162/3 + +163/3 + +Ada Reference Manual — 2012 Edition + +function Contains (Container : Tree; + Item : Element_Type) return Boolean; + +Equivalent to Find (Container, Item) /= No_Element. + +procedure Iterate + (Container : in Tree; + Process : not null access procedure (Position : in Cursor)); + +Iterate calls Process.all with a cursor that designates each element in Container, starting with the +root node and proceeding in a depth-first order. Tampering with the cursors of Container is +prohibited during the execution of a call on Process.all. Any exception raised by Process.all is +propagated. + +procedure Iterate_Subtree + (Position : in Cursor; + Process : not null access procedure (Position : in Cursor)); + +If Position equals No_Element, then Constraint_Error is propagated. Otherwise, Iterate_Subtree +calls Process.all with a cursor that designates each element in the subtree rooted by the node +designated by Position, starting with the node designated by Position and proceeding in a depth- +first order. Tampering with the cursors of the tree that contains the element designated by +Position is prohibited during the execution of a call on Process.all. Any exception raised by +Process.all is propagated. + +function Iterate (Container : in Tree) + return Tree_Iterator_Interfaces.Forward_Iterator'Class; + +Iterate returns an iterator object (see 5.5.1) that will generate a value for a loop parameter (see +5.5.2) designating each node in Container, starting with the root node and proceeding in a depth- +first order. Tampering with the cursors of Container is prohibited while the iterator object exists +loop_statement whose +(in +iterator_specification denotes this object). The iterator object needs finalization. + +sequence_of_statements + +particular, + +the + +the + +of + +in + +function Iterate_Subtree (Position : in Cursor) + return Tree_Iterator_Interfaces.Forward_Iterator'Class; + +If Position equals No_Element, then Constraint_Error is propagated. Otherwise, Iterate_Subtree +returns an iterator object (see 5.5.1) that will generate a value for a loop parameter (see 5.5.2) +designating each element in the subtree rooted by the node designated by Position, starting with +the node designated by Position and proceeding in a depth-first order. If Position equals +No_Element, then Constraint_Error is propagated. Tampering with the cursors of the container +that contains the node designated by Position is prohibited while the iterator object exists (in +particular, in the sequence_of_statements of the loop_statement whose iterator_specification +denotes this object). The iterator object needs finalization. + +function Child_Count (Parent : Cursor) return Count_Type; + +Child_Count returns the number of child nodes of the node designated by Parent. + +function Child_Depth (Parent, Child : Cursor) return Count_Type; + +If Child or Parent is equal to No_Element, then Constraint_Error is propagated. Otherwise, +Child_Depth returns the number of ancestor nodes of Child (including Child itself), up to but not +including Parent; Program_Error is propagated if Parent is not an ancestor of Child. + +A.18.10 The Generic Package Containers.Multiway_Trees + +13 December 2012 546 + + Ada Reference Manual — 2012 Edition + +procedure Insert_Child (Container : in out Tree; + Parent : in Cursor; + Before : in Cursor; + New_Item : in Element_Type; + Count : in Count_Type := 1); + +If Parent equals No_Element, then Constraint_Error is propagated. If Parent does not designate a +node in Container, then Program_Error is propagated. If Before is not equal to No_Element, and +does not designate a node in Container, then Program_Error is propagated. If Before is not equal +to No_Element, and Parent does not designate the parent node of the node designated by Before, +then Constraint_Error is propagated. Otherwise, Insert_Child allocates Count nodes containing +copies of New_Item and inserts them as children of Parent. If Parent already has child nodes, +then the new nodes are inserted prior to the node designated by Before, or, if Before equals +No_Element, the new nodes are inserted after the last existing child node of Parent. Any +exception raised during allocation of internal storage is propagated, and Container is not +modified. + +procedure Insert_Child (Container : in out Tree; + Parent : in Cursor; + Before : in Cursor; + New_Item : in Element_Type; + Position : out Cursor; + Count : in Count_Type := 1); + +If Parent equals No_Element, then Constraint_Error is propagated. If Parent does not designate a +node in Container, then Program_Error is propagated. If Before is not equal to No_Element, and +does not designate a node in Container, then Program_Error is propagated. If Before is not equal +to No_Element, and Parent does not designate the parent node of the node designated by Before, +then Constraint_Error is propagated. Otherwise, Insert_Child allocates Count nodes containing +copies of New_Item and inserts them as children of Parent. If Parent already has child nodes, +then the new nodes are inserted prior to the node designated by Before, or, if Before equals +No_Element, the new nodes are inserted after the last existing child node of Parent. Position +designates the first newly-inserted node, or if Count equals 0, then Position is assigned the value +of Before. Any exception raised during allocation of internal storage is propagated, and +Container is not modified. + +procedure Insert_Child (Container : in out Tree; + Parent : in Cursor; + Before : in Cursor; + Position : out Cursor; + Count : in Count_Type := 1); + +If Parent equals No_Element, then Constraint_Error is propagated. If Parent does not designate a +node in Container, then Program_Error is propagated. If Before is not equal to No_Element, and +does not designate a node in Container, then Program_Error is propagated. If Before is not equal +to No_Element, and Parent does not designate the parent node of the node designated by Before, +then Constraint_Error is propagated. Otherwise, Insert_Child allocates Count nodes, the +elements contained in the new nodes are initialized by default (see 3.3.1), and the new nodes are +inserted as children of Parent. If Parent already has child nodes, then the new nodes are inserted +prior to the node designated by Before, or, if Before equals No_Element, the new nodes are +inserted after the last existing child node of Parent. Position designates the first newly-inserted +node, or if Count equals 0, then Position is assigned the value of Before. Any exception raised +during allocation of internal storage is propagated, and Container is not modified. + +164/3 + +165/3 + +166/3 + +167/3 + +168/3 + +169/3 + +547 13 December 2012 + +The Generic Package Containers.Multiway_Trees A.18.10 + + Ada Reference Manual — 2012 Edition + +170/3 + +171/3 + +172/3 + +173/3 + +174/3 + +175/3 + +176/3 + +177/3 + +178/3 + +179/3 + +procedure Prepend_Child (Container : in out Tree; + Parent : in Cursor; + New_Item : in Element_Type; + Count : in Count_Type := 1); + +Equivalent to Insert_Child (Container, Parent, First_Child (Container, Parent), New_Item, +Count). + +procedure Append_Child (Container : in out Tree; + Parent : in Cursor; + New_Item : in Element_Type; + Count : in Count_Type := 1); + +Equivalent to Insert_Child (Container, Parent, No_Element, New_Item, Count). + +procedure Delete_Children (Container : in out Tree; + Parent : in Cursor); + +If Parent equals No_Element, then Constraint_Error is propagated. If Parent does not designate a +node in Container, Program_Error is propagated. Otherwise, Delete_Children removes (from +Container) all of the descendants of Parent other than Parent itself. + +procedure Copy_Subtree (Target : in out Tree; + Parent : in Cursor; + Before : in Cursor; + Source : in Cursor); + +If Parent equals No_Element, then Constraint_Error is propagated. If Parent does not designate a +node in Target, then Program_Error is propagated. If Before is not equal to No_Element, and +does not designate a node in Target, then Program_Error is propagated. If Before is not equal to +No_Element, and Parent does not designate the parent node of the node designated by Before, +then Constraint_Error is propagated. If Source designates a root node, then Constraint_Error is +propagated. If Source is equal to No_Element, then the operation has no effect. Otherwise, the +subtree rooted by Source (which can be from any tree; it does not have to be a subtree of Target) +is copied (new nodes are allocated to create a new subtree with the same structure as the Source +subtree, with each element initialized from the corresponding element of the Source subtree) and +inserted into Target as a child of Parent. If Parent already has child nodes, then the new nodes +are inserted prior to the node designated by Before, or, if Before equals No_Element, the new +nodes are inserted after the last existing child node of Parent. The parent of the newly created +subtree is set to Parent, and the overall count of Target is incremented by Subtree_Node_Count +(Source). Any exception raised during allocation of internal storage is propagated, and Container +is not modified. + +procedure Splice_Subtree (Target : in out Tree; + Parent : in Cursor; + Before : in Cursor; + Source : in out Tree; + Position : in out Cursor); + +If Parent equals No_Element, then Constraint_Error is propagated. If Parent does not designate a +node in Target, then Program_Error is propagated. If Before is not equal to No_Element, and +does not designate a node in Target, then Program_Error is propagated. If Before is not equal to +No_Element, and Parent does not designate the parent node of the node designated by Before, +then Constraint_Error is propagated. If Position equals No_Element, Constraint_Error is +propagated. If Position does not designate a node in Source or designates a root node, then +Program_Error is propagated. If Source denotes the same object as Target, then: if Position +equals Before there is no effect; if Position designates an ancestor of Parent (including Parent +itself), Constraint_Error is propagated; otherwise, the subtree rooted by the element designated + +A.18.10 The Generic Package Containers.Multiway_Trees + +13 December 2012 548 + + Ada Reference Manual — 2012 Edition + +by Position is moved to be a child of Parent. If Parent already has child nodes, then the moved +nodes are inserted prior to the node designated by Before, or, if Before equals No_Element, the +moved nodes are inserted after the last existing child node of Parent. In each of these cases, +Position and the count of Target are unchanged, and the parent of the element designated by +Position is set to Parent. + +Otherwise (if Source does not denote the same object as Target), the subtree designated by +Position is removed from Source and moved to Target. The subtree is inserted as a child of +Parent. If Parent already has child nodes, then the moved nodes are inserted prior to the node +designated by Before, or, if Before equals No_Element, the moved nodes are inserted after the +last existing child node of Parent. In each of these cases, the count of Target is incremented by +Subtree_Node_Count +is decremented by +Subtree_Node_Count (Position), Position is updated to represent an element in Target. + +count of Source + +(Position), + +and + +the + +procedure Splice_Subtree (Container: in out Tree; + Parent : in Cursor; + Before : in Cursor; + Position : in Cursor); + +If Parent equals No_Element, then Constraint_Error is propagated. If Parent does not designate a +node in Container, then Program_Error is propagated. If Before is not equal to No_Element, and +does not designate a node in Container, then Program_Error is propagated. If Before is not equal +to No_Element, and Parent does not designate the parent node of the node designated by Before, +then Constraint_Error is propagated. If Position equals No_Element, Constraint_Error is +propagated. If Position does not designate a node in Container or designates a root node, then +Program_Error is propagated. If Position equals Before, there is no effect. If Position designates +an ancestor of Parent (including Parent itself), Constraint_Error is propagated. Otherwise, the +subtree rooted by the element designated by Position is moved to be a child of Parent. If Parent +already has child nodes, then the moved nodes are inserted prior to the node designated by +Before, or, if Before equals No_Element, the moved nodes are inserted after the last existing +child node of Parent. The parent of the element designated by Position is set to Parent. + +procedure Splice_Children (Target : in out Tree; + Target_Parent : in Cursor; + Before : in Cursor; + Source : in out Tree; + Source_Parent : in Cursor); + +If Target_Parent equals No_Element, then Constraint_Error is propagated. If Target_Parent does +not designate a node in Target, then Program_Error is propagated. If Before is not equal to +No_Element, and does not designate an element in Target, then Program_Error is propagated. If +Source_Parent equals No_Element, then Constraint_Error is propagated. If Source_Parent does +not designate a node in Source, then Program_Error is propagated. If Before is not equal to +No_Element, and Target_Parent does not designate the parent node of the node designated by +Before, then Constraint_Error is propagated. + +If Source denotes the same object as Target, then: + +• +• + +• + +if Target_Parent equals Source_Parent there is no effect; else + +if Source_Parent is an ancestor of Target_Parent other than Target_Parent itself, then +Constraint_Error is propagated; else + +the child elements (and the further descendants) of Source_Parent are moved to be +child elements of Target_Parent. If Target_Parent already has child elements, then the +moved elements are inserted prior to the node designated by Before, or, if Before + +549 13 December 2012 + +The Generic Package Containers.Multiway_Trees A.18.10 + +180/3 + +181/3 + +182/3 + +183/3 + +184/3 + +185/3 + +186/3 + +187/3 + +188/3 + + Ada Reference Manual — 2012 Edition + +equals No_Element, the moved elements are inserted after the last existing child node +of Target_Parent. The parent of each moved child element is set to Target_Parent. + +Otherwise (if Source does not denote the same object as Target), the child elements (and the +further descendants) of Source_Parent are removed from Source and moved to Target. The child +elements are inserted as children of Target_Parent. If Target_Parent already has child elements, +then the moved elements are inserted prior to the node designated by Before, or, if Before equals +No_Element, the moved elements are inserted after the last existing child node of Target_Parent. +In each of these cases, the overall count of Target is incremented by Subtree_Node_Count +(Source_Parent)-1, and the overall count of Source is decremented by Subtree_Node_Count +(Source_Parent)-1. + +procedure Splice_Children (Container : in out Tree; + Target_Parent : in Cursor; + Before : in Cursor; + Source_Parent : in Cursor); + +If Target_Parent equals No_Element, then Constraint_Error is propagated. If Target_Parent does +not designate a node in Container, then Program_Error is propagated. If Before is not equal to +No_Element, and does not designate an element in Container, then Program_Error is propagated. +If Source_Parent equals No_Element, then Constraint_Error is propagated. If Source_Parent +does not designate a node in Container, then Program_Error is propagated. If Before is not equal +to No_Element, and Target_Parent does not designate the parent node of the node designated by +Before, then Constraint_Error is propagated. If Target_Parent equals Source_Parent there is no +effect. If Source_Parent is an ancestor of Target_Parent other than Target_Parent itself, then +Constraint_Error is propagated. Otherwise, the child elements (and the further descendants) of +Source_Parent are moved to be child elements of Target_Parent. If Target_Parent already has +child elements, then the moved elements are inserted prior to the node designated by Before, or, +if Before equals No_Element, the moved elements are inserted after the last existing child node +of Target_Parent. The parent of each moved child element is set to Target_Parent. + +function Parent (Position : Cursor) return Cursor; + +If Position is equal to No_Element or designates a root node, No_Element is returned. +Otherwise, a cursor designating the parent node of the node designated by Position is returned. + +function First_Child (Parent : Cursor) return Cursor; + +If Parent is equal to No_Element, then Constraint_Error is propagated. Otherwise, First_Child +returns a cursor designating the first child node of the node designated by Parent; if there is no +such node, No_Element is returned. + +function First_Child_Element (Parent : Cursor) return Element_Type; + +Equivalent to Element (First_Child (Parent)). + +function Last_Child (Parent : Cursor) return Cursor; + +If Parent is equal to No_Element, then Constraint_Error is propagated. Otherwise, Last_Child +returns a cursor designating the last child node of the node designated by Parent; if there is no +such node, No_Element is returned. + +function Last_Child_Element (Parent : Cursor) return Element_Type; + +Equivalent to Element (Last_Child (Parent)). + +189/3 + +190/3 + +191/3 + +192/3 + +193/3 + +194/3 + +195/3 + +196/3 + +197/3 + +198/3 + +199/3 + +200/3 + +201/3 + +A.18.10 The Generic Package Containers.Multiway_Trees + +13 December 2012 550 + + Ada Reference Manual — 2012 Edition + +function Next_Sibling (Position : Cursor) return Cursor; + +If Position equals No_Element or designates the last child node of its parent, then Next_Sibling +returns the value No_Element. Otherwise, it returns a cursor that designates the successor (with +the same parent) of the node designated by Position. + +function Previous_Sibling (Position : Cursor) return Cursor; + +If Position equals No_Element or designates the first child node of its parent, then +Previous_Sibling returns the value No_Element. Otherwise, it returns a cursor that designates the +predecessor (with the same parent) of the node designated by Position. + +procedure Next_Sibling (Position : in out Cursor); + +Equivalent to Position := Next_Sibling (Position); + +procedure Previous_Sibling (Position : in out Cursor); + +Equivalent to Position := Previous_Sibling (Position); + +procedure Iterate_Children + (Parent : in Cursor; + Process : not null access procedure (Position : in Cursor)); + +If Parent equals No_Element, then Constraint_Error is propagated. + +Iterate_Children calls Process.all with a cursor that designates each child node of Parent, starting +with the first child node and moving the cursor as per the Next_Sibling function. + +Tampering with the cursors of the tree containing Parent is prohibited during the execution of a +call on Process.all. Any exception raised by Process.all is propagated. + +procedure Reverse_Iterate_Children + (Parent : in Cursor; + Process : not null access procedure (Position : in Cursor)); + +If Parent equals No_Element, then Constraint_Error is propagated. + +Reverse_Iterate_Children calls Process.all with a cursor that designates each child node of +Parent, starting with the last child node and moving the cursor as per the Previous_Sibling +function. + +Tampering with the cursors of the tree containing Parent is prohibited during the execution of a +call on Process.all. Any exception raised by Process.all is propagated. + +function Iterate_Children (Container : in Tree; Parent : in Cursor) + return Tree_Iterator_Interfaces.Reversible_Iterator'Class; + +Iterate_Children returns a reversible iterator object (see 5.5.1) that will generate a value for a +loop parameter (see 5.5.2) designating each child node of Parent. If Parent equals No_Element, +then Constraint_Error is propagated. If Parent does not designate a node in Container, then +Program_Error is propagated. Otherwise, when used as a forward iterator, the nodes are +designated starting with the first child node and moving the cursor as per the function +Next_Sibling; when used as a reverse iterator, the nodes are designated starting with the last +child node and moving the cursor as per the function Previous_Sibling. Tampering with the +cursors of Container is prohibited while the iterator object exists (in particular, in the +sequence_of_statements of the loop_statement whose iterator_specification denotes this +object). The iterator object needs finalization. + +202/3 + +203/3 + +204/3 + +205/3 + +206/3 + +207/3 + +208/3 + +209/3 + +210/3 + +211/3 + +212/3 + +213/3 + +214/3 + +215/3 + +216/3 + +217/3 + +218/3 + +219/3 + +551 13 December 2012 + +The Generic Package Containers.Multiway_Trees A.18.10 + + Ada Reference Manual — 2012 Edition + +Bounded (Run-Time) Errors + +220/3 + +221/3 + +It is a bounded error for the actual function associated with a generic formal subprogram, when called as +part of an operation of this package, to tamper with elements of any Tree parameter of the operation. +Either Program_Error is raised, or the operation works as defined on the value of the Tree either prior to, +or subsequent to, some or all of the modifications to the Tree. + +It is a bounded error to call any subprogram declared in the visible part of Containers.Multiway_Trees +when the associated container has been finalized. If the operation takes Container as an in out parameter, +then it raises Constraint_Error or Program_Error. Otherwise, the operation either proceeds as it would for +an empty container, or it raises Constraint_Error or Program_Error. + +Erroneous Execution + +222/3 + +A Cursor value is invalid if any of the following have occurred since it was created: + +223/3 + +224/3 + +• The tree that contains the element it designates has been finalized; +• The tree that contains the element it designates has been used as the Source or Target of a call to + +Move; + +225/3 + +• The tree that contains the element it designates has been used as the Target of a call to Assign or + +the target of an assignment_statement; + +226/3 + +227/3 + +• The element it designates has been removed from the tree that previously contained the element. + +The result of "=" or Has_Element is unspecified if it is called with an invalid cursor parameter. Execution +is erroneous if any other subprogram declared in Containers.Multiway_Trees is called with an invalid +cursor parameter. + +228/3 + +Execution is erroneous if the tree associated with the result of a call to Reference or Constant_Reference is +finalized before the result object returned by the call to Reference or Constant_Reference is finalized. + +Implementation Requirements + +229/3 + +No storage associated with a multiway tree object shall be lost upon assignment or scope exit. + +230/3 + +The execution of an assignment_statement for a tree shall have the effect of copying the elements from +the source tree object to the target tree object and changing the node count of the target object to that of +the source object. + +Implementation Advice + +231/3 + +Containers.Multiway_Trees should be implemented similarly to a multiway tree. In particular, if N is the +overall number of nodes for a particular tree, then the worst-case time complexity of Element, Parent, +First_Child, Last_Child, Next_Sibling, Previous_Sibling, Insert_Child with Count=1, and Delete should +be O(log N). + +232/3 + +Move should not copy elements, and should minimize copying of internal data structures. + +233/3 + +If an exception is propagated from a tree operation, no storage should be lost, nor any elements removed +from a tree unless specified by the operation. + +A.18.11 The Generic Package Containers.Indefinite_Vectors + +1/2 + +The language-defined generic package Containers.Indefinite_Vectors provides a private type Vector and a +set of operations. It provides the same operations as the package Containers.Vectors (see A.18.2), with the +difference that the generic formal Element_Type is indefinite. + +A.18.10 The Generic Package Containers.Multiway_Trees + +13 December 2012 552 + + The declaration of the generic library package Containers.Indefinite_Vectors has the same contents and +semantics as Containers.Vectors except: + +Static Semantics + +Ada Reference Manual — 2012 Edition + +• The generic formal Element_Type is indefinite. +• The procedures with the profiles: + +procedure Insert (Container : in out Vector; + Before : in Extended_Index; + Count : in Count_Type := 1); +procedure Insert (Container : in out Vector; + Before : in Cursor; + Position : out Cursor; + Count : in Count_Type := 1); +are omitted. + +• The actual Element parameter of access subprogram Process of Update_Element may be + +constrained even if Element_Type is unconstrained. + +A.18.12 The Generic Package +Containers.Indefinite_Doubly_Linked_Lists + +The language-defined generic package Containers.Indefinite_Doubly_Linked_Lists provides private types +List and Cursor, and a set of operations for each type. It provides the same operations as the package +Containers.Doubly_Linked_Lists (see A.18.3), with the difference that the generic formal Element_Type +is indefinite. + +The declaration of the generic library package Containers.Indefinite_Doubly_Linked_Lists has the same +contents and semantics as Containers.Doubly_Linked_Lists except: + +Static Semantics + +• The generic formal Element_Type is indefinite. +• The procedure with the profile: + +procedure Insert (Container : in out List; + Before : in Cursor; + Position : out Cursor; + Count : in Count_Type := 1); +is omitted. + +• The actual Element parameter of access subprogram Process of Update_Element may be + +constrained even if Element_Type is unconstrained. + +A.18.13 The Generic Package Containers.Indefinite_Hashed_Maps + +The language-defined generic package Containers.Indefinite_Hashed_Maps provides a map with the same +operations as the package Containers.Hashed_Maps (see A.18.5), with the difference that the generic +formal types Key_Type and Element_Type are indefinite. + +Static Semantics + +The declaration of the generic library package Containers.Indefinite_Hashed_Maps has the same contents +and semantics as Containers.Hashed_Maps except: +• The generic formal Key_Type is indefinite. +• The generic formal Element_Type is indefinite. + +553 13 December 2012 + +The Generic Package Containers.Indefinite_Vectors A.18.11 + +2/3 + +3/2 + +4/2 + +5/2 + +6/2 + +7/2 + +8/2 + +1/2 + +2/3 + +3/2 + +4/2 + +5/2 + +6/2 + +7/2 + +1/2 + +2/3 + +3/2 + +4/2 + + + + 5/2 + +6/2 + +7/2 + +8/2 + +1/2 + +2/3 + +3/2 + +4/2 + +5/2 + +6/2 + +7/2 + +8/2 + +1/2 + +2/3 + +3/2 + +4/2 + +1/2 + +Ada Reference Manual — 2012 Edition + +• The procedure with the profile: + +procedure Insert (Container : in out Map; + Key : in Key_Type; + Position : out Cursor; + Inserted : out Boolean); +is omitted. + +• The actual Element parameter of access subprogram Process of Update_Element may be + +constrained even if Element_Type is unconstrained. + +A.18.14 The Generic Package Containers.Indefinite_Ordered_Maps + +The language-defined generic package Containers.Indefinite_Ordered_Maps provides a map with the same +operations as the package Containers.Ordered_Maps (see A.18.6), with the difference that the generic +formal types Key_Type and Element_Type are indefinite. + +Static Semantics + +The declaration of the generic library package Containers.Indefinite_Ordered_Maps has the same contents +and semantics as Containers.Ordered_Maps except: +• The generic formal Key_Type is indefinite. +• The generic formal Element_Type is indefinite. +• The procedure with the profile: + +procedure Insert (Container : in out Map; + Key : in Key_Type; + Position : out Cursor; + Inserted : out Boolean); +is omitted. + +• The actual Element parameter of access subprogram Process of Update_Element may be + +constrained even if Element_Type is unconstrained. + +A.18.15 The Generic Package Containers.Indefinite_Hashed_Sets + +The language-defined generic package Containers.Indefinite_Hashed_Sets provides a set with the same +operations as the package Containers.Hashed_Sets (see A.18.8), with the difference that the generic formal +type Element_Type is indefinite. + +Static Semantics + +The declaration of the generic library package Containers.Indefinite_Hashed_Sets has the same contents +and semantics as Containers.Hashed_Sets except: + +• The generic formal Element_Type is indefinite. +• The actual Element parameter of access subprogram Process of Update_Element_- + +Preserving_Key may be constrained even if Element_Type is unconstrained. + +A.18.16 The Generic Package Containers.Indefinite_Ordered_Sets + +The language-defined generic package Containers.Indefinite_Ordered_Sets provides a set with the same +operations as the package Containers.Ordered_Sets (see A.18.9), with the difference that the generic +formal type Element_Type is indefinite. + +A.18.13 The Generic Package Containers.Indefinite_Hashed_Maps + +13 December 2012 554 + + + + Ada Reference Manual — 2012 Edition + +Static Semantics + +The declaration of the generic library package Containers.Indefinite_Ordered_Sets has the same contents +and semantics as Containers.Ordered_Sets except: + +• The generic formal Element_Type is indefinite. +• The actual Element parameter of access subprogram Process of Update_Element_- + +Preserving_Key may be constrained even if Element_Type is unconstrained. + +A.18.17 The Generic Package Containers.Indefinite_Multiway_Trees + +The language-defined generic package Containers.Indefinite_Multiway_Trees provides a multiway tree +with the same operations as the package Containers.Multiway_Trees (see A.18.10), with the difference +that the generic formal Element_Type is indefinite. + +The declaration of the generic library package Containers.Indefinite_Multiway_Trees has the same +contents and semantics as Containers.Multiway_Trees except: + +Static Semantics + +• The generic formal Element_Type is indefinite. +• The procedure with the profile: + +procedure Insert_Child (Container : in out Tree; + Parent : in Cursor; + Before : in Cursor; + Position : out Cursor; + Count : in Count_Type := 1); +is omitted. + +• The actual Element parameter of access subprogram Process of Update_Element may be + +constrained even if Element_Type is unconstrained. + +A.18.18 The Generic Package Containers.Indefinite_Holders + +The language-defined generic package Containers.Indefinite_Holders provides a private type Holder and a +set of operations for that type. A holder container holds a single element of an indefinite type. + +A holder container allows the declaration of an object that can be used like an uninitialized variable or +component of an indefinite type. + +A holder container may be empty. An empty holder does not contain an element. + +The generic library package Containers.Indefinite_Holders has the following declaration: + +Static Semantics + +generic + type Element_Type (<>) is private; + with function "=" (Left, Right : Element_Type) return Boolean is <>; +package Ada.Containers.Indefinite_Holders is + pragma Preelaborate(Indefinite_Holders); + pragma Remote_Types(Indefinite_Holders); + type Holder is tagged private; + pragma Preelaborable_Initialization (Holder); + Empty_Holder : constant Holder; + function "=" (Left, Right : Holder) return Boolean; + function To_Holder (New_Item : Element_Type) return Holder; + +2/3 + +3/2 + +4/2 + +1/3 + +2/3 + +3/3 + +4/3 + +5/3 + +6/3 + +7/3 + +1/3 + +2/3 + +3/3 + +4/3 + +5/3 + +6/3 + +7/3 + +8/3 + +9/3 + +555 13 December 2012 + +The Generic Package Containers.Indefinite_Ordered_Sets A.18.16 + + + Ada Reference Manual — 2012 Edition + +10/3 + +11/3 + +12/3 + +13/3 + +14/3 + +15/3 + +16/3 + +17/3 + +18/3 + +19/3 + +20/3 + +21/3 + +22/3 + +23/3 + +24/3 + +25/3 + +26/3 + + function Is_Empty (Container : Holder) return Boolean; + procedure Clear (Container : in out Holder); + function Element (Container : Holder) return Element_Type; + procedure Replace_Element (Container : in out Holder; + New_Item : in Element_Type); + procedure Query_Element + (Container : in Holder; + Process : not null access procedure (Element : in Element_Type)); + procedure Update_Element + (Container : in out Holder; + Process : not null access procedure (Element : in out Element_Type)); + type Constant_Reference_Type + (Element : not null access constant Element_Type) is private + with Implicit_Dereference => Element; + type Reference_Type (Element : not null access Element_Type) is private + with Implicit_Dereference => Element; + function Constant_Reference (Container : aliased in Holder) + return Constant_Reference_Type; + function Reference (Container : aliased in out Holder) + return Reference_Type; + procedure Assign (Target : in out Holder; Source : in Holder); + function Copy (Source : Holder) return Holder; + procedure Move (Target : in out Holder; Source : in out Holder); +private + ... -- not specified by the language +end Ada.Containers.Indefinite_Holders; + +The actual function for the generic formal function "=" on Element_Type values is expected to define a +reflexive and symmetric relationship and return the same result value each time it is called with a +particular pair of values. If it behaves in some other manner, the function "=" on holder values returns an +unspecified value. The exact arguments and number of calls of this generic formal function by the function +"=" on holder values are unspecified. + +27/3 + +The type Holder is used to represent holder containers. The type Holder needs finalization (see 7.6). + +28/3 + +29/3 + +30/3 + +31/3 + +32/3 + +33/3 + +34/3 + +Empty_Holder represents an empty holder object. If an object of type Holder is not otherwise initialized, it +is initialized to the same value as Empty_Holder. + +Some operations of this generic package have access-to-subprogram parameters. To ensure such +operations are well-defined, they guard against certain actions by the designated subprogram. In particular, +some operations check for “tampering with the element” of a container because they depend on the +element of the container not being replaced. + +A subprogram is said to tamper with the element of a holder object H if: + +• It clears the element contained by H, that is, it calls the Clear procedure with H as a parameter; +• It replaces the element contained by H, that is, it calls the Replace_Element procedure with H as + +a parameter; + +• It calls the Move procedure with H as a parameter; +• It finalizes H. + +A.18.18 The Generic Package Containers.Indefinite_Holders + +13 December 2012 556 + + Ada Reference Manual — 2012 Edition + +When tampering with the element is prohibited for a particular holder object H, Program_Error is +propagated by a call of any language-defined subprogram that is defined to tamper with the element of H, +leaving H unmodified. + +function "=" (Left, Right : Holder) return Boolean; + +If Left and Right denote the same holder object, then the function returns True. Otherwise, it +compares the element contained in Left to the element contained in Right using the generic +formal equality operator, returning the result of that operation. Any exception raised during the +evaluation of element equality is propagated. + +function To_Holder (New_Item : Element_Type) return Holder; + +Returns a nonempty holder containing an element initialized to New_Item. + +function Is_Empty (Container : Holder) return Boolean; + +Returns True if Container is empty, and False if it contains an element. + +procedure Clear (Container : in out Holder); + +Removes the element from Container. Container is empty after a successful Clear operation. + +function Element (Container : Holder) return Element_Type; + +If Container is empty, Constraint_Error is propagated. Otherwise, returns the element stored in +Container. + +procedure Replace_Element (Container : in out Holder; + New_Item : in Element_Type); + +Replace_Element assigns the value New_Item into Container, replacing any preexisting content +of Container. Container is not empty after a successful call to Replace_Element. + +procedure Query_Element + (Container : in Holder; + Process : not null access procedure (Element : in Element_Type)); + +If Container is empty, Constraint_Error is propagated. Otherwise, Query_Element calls +Process.all with the contained element as the argument. Tampering with the element of +Container is prohibited during the execution of the call on Process.all. Any exception raised by +Process.all is propagated. + +procedure Update_Element + (Container : in out Holder; + Process : not null access procedure (Element : in out Element_Type)); + +If Container is empty, Constraint_Error is propagated. Otherwise, Update_Element calls +Process.all with the contained element as the argument. Tampering with the element of +Container is prohibited during the execution of the call on Process.all. Any exception raised by +Process.all is propagated. + +type Constant_Reference_Type + (Element : not null access constant Element_Type) is private + with Implicit_Dereference => Element; +type Reference_Type (Element : not null access Element_Type) is private + with Implicit_Dereference => Element; + +The types Constant_Reference_Type and Reference_Type need finalization. + +35/3 + +36/3 + +37/3 + +38/3 + +39/3 + +40/3 + +41/3 + +42/3 + +43/3 + +44/3 + +45/3 + +46/3 + +47/3 + +48/3 + +49/3 + +50/3 + +51/3 + +52/3 + +53/3 + +54/3 + +557 13 December 2012 + +The Generic Package Containers.Indefinite_Holders A.18.18 + + Ada Reference Manual — 2012 Edition + +55/3 + +56/3 + +57/3 + +58/3 + +59/3 + +60/3 + +61/3 + +62/3 + +63/3 + +64/3 + +65/3 + +66/3 + +67/3 + +68/3 + +69/3 + +The default initialization of an object of type Constant_Reference_Type or Reference_Type +propagates Program_Error. + +function Constant_Reference (Container : aliased in Holder) + return Constant_Reference_Type; + +This function (combined with the Implicit_Dereference aspect) provides a convenient way to +gain read access to the contained element of a holder container. + +If Container is empty, Constraint_Error is propagated. Otherwise, Constant_Reference returns an +object whose discriminant is an access value that designates the contained element. Tampering +with the elements of Container is prohibited while the object returned by Constant_Reference +exists and has not been finalized. + +function Reference (Container : aliased in out Holder) + return Reference_Type; + +This function (combined with the Implicit_Dereference aspects) provides a convenient way to +gain read and write access to the contained element of a holder container. + +If Container is empty, Constraint_Error is propagated. Otherwise, Reference returns an object +whose discriminant is an access value that designates the contained element. Tampering with the +elements of Container is prohibited while the object returned by Reference exists and has not +been finalized. + +procedure Assign (Target : in out Holder; Source : in Holder); + +If Target denotes the same object as Source, the operation has no effect. If Source is empty, +Clear (Target) is called. Otherwise, Replace_Element (Target, Element (Source)) is called. + +function Copy (Source : Holder) return Holder; + +If Source is empty, returns an empty holder container; otherwise, returns To_Holder (Element +(Source)). + +procedure Move (Target : in out Holder; Source : in out Holder); + +If Target denotes the same object as Source, then the operation has no effect. Otherwise, the +element contained by Source (if any) is removed from Source and inserted into Target, replacing +any preexisting content. Source is empty after a successful call to Move. + +Bounded (Run-Time) Errors + +It is a bounded error for the actual function associated with a generic formal subprogram, when called as +part of an operation of this package, to tamper with the element of any Holder parameter of the operation. +Either Program_Error is raised, or the operation works as defined on the value of the Holder either prior +to, or subsequent to, some or all of the modifications to the Holder. + +It is a bounded error to call any subprogram declared in the visible part of Containers.Indefinite_Holders +when the associated container has been finalized. If the operation takes Container as an in out parameter, +then it raises Constraint_Error or Program_Error. Otherwise, the operation either proceeds as it would for +an empty container, or it raises Constraint_Error or Program_Error. + +70/3 + +Execution is erroneous if the holder container associated with the result of a call to Reference or +Constant_Reference is finalized before the result object returned by the call to Reference or +Constant_Reference is finalized. + +Erroneous Execution + +A.18.18 The Generic Package Containers.Indefinite_Holders + +13 December 2012 558 + + Ada Reference Manual — 2012 Edition + +No storage associated with a holder object shall be lost upon assignment or scope exit. + +Implementation Requirements + +The execution of an assignment_statement for a holder container shall have the effect of copying the +element (if any) from the source holder object to the target holder object. + +Move should not copy the element, and should minimize copying of internal data structures. + +Implementation Advice + +If an exception is propagated from a holder operation, no storage should be lost, nor should the element be +removed from a holder container unless specified by the operation. + +A.18.19 The Generic Package Containers.Bounded_Vectors + +The language-defined generic package Containers.Bounded_Vectors provides a private type Vector and a +set of operations. It provides the same operations as the package Containers.Vectors (see A.18.2), with the +difference that the maximum storage is bounded. + +The declaration of the generic library package Containers.Bounded_Vectors has the same contents and +semantics as Containers.Vectors except: + +Static Semantics + +• The pragma Preelaborate is replaced with pragma Pure. +• The type Vector is declared with a discriminant that specifies the capacity: + type Vector (Capacity : Count_Type) is tagged private; + +• The type Vector needs finalization if and only if type Element_Type needs finalization. +• In function Copy, if the Capacity parameter is equal to or greater than the length of Source, the + +vector capacity exactly equals the value of the Capacity parameter. + +• The description of Reserve_Capacity is replaced with: + +If the specified Capacity is larger than the capacity of Container, then Reserve_Capacity +propagates Capacity_Error. Otherwise, the operation has no effect. + +71/3 + +72/3 + +73/3 + +74/3 + +1/3 + +2/3 + +3/3 + +4/3 + +5/3 + +6/3 + +7/3 + +8/3 + +9/3 + +It is a bounded error to assign from a bounded vector object while tampering with elements or cursors of +that object is prohibited. Either Program_Error is raised by the assignment, execution proceeds with the +target object prohibiting tampering with elements or cursors, or execution proceeds normally. + +10/3 + +Bounded (Run-Time) Errors + +When a bounded vector object V is finalized, if tampering with cursors is prohibited for V other than due +to an assignment from another vector, then execution is erroneous. + +11/3 + +Erroneous Execution + +Implementation Requirements + +For each instance of Containers.Vectors and each instance of Containers.Bounded_Vectors, if the two +instances meet the following conditions, then the output generated by the Vector'Output or Vector'Write +subprograms of either instance shall be readable by the Vector'Input or Vector'Read of the other instance, +respectively: + +• + +the Element_Type parameters of the two instances are statically matching subtypes of the same +type; and + +12/3 + +13/3 + +559 13 December 2012 + +The Generic Package Containers.Indefinite_Holders A.18.18 + + Ada Reference Manual — 2012 Edition + +14/3 + +15/3 + +• + +• + +the output generated by Element_Type'Output or Element_Type'Write is readable by +Element_Type'Input or Element_Type'Read, respectively (where Element_Type denotes the +type of the two actual Element_Type parameters); and + +the preceding two conditions also hold for the Index_Type parameters of the instances. + +16/3 + +Bounded vector objects should be implemented without implicit pointers or dynamic allocation. + +17/3 + +The implementation advice for procedure Move to minimize copying does not apply. + +Implementation Advice + +A.18.20 The Generic Package +Containers.Bounded_Doubly_Linked_Lists + +1/3 + +2/3 + +3/3 + +4/3 + +5/3 + +6/3 + +7/3 + +8/3 + +9/3 + +10/3 + +11/3 + +12/3 + +The language-defined generic package Containers.Bounded_Doubly_Linked_Lists provides a private type +List +package +provides +Containers.Doubly_Linked_Lists (see A.18.3), with the difference that the maximum storage is bounded. + +operations. + +operations + +same + +and + +the + +the + +set + +of + +as + +It + +a + +Static Semantics + +The declaration of the generic library package Containers.Bounded_Doubly_Linked_Lists has the same +contents and semantics as Containers.Doubly_Linked_Lists except: + +• The pragma Preelaborate is replaced with pragma Pure. +• The type List is declared with a discriminant that specifies the capacity (maximum number of + +elements) as follows: + type List (Capacity : Count_Type) is tagged private; + +• The type List needs finalization if and only if type Element_Type needs finalization. +• The allocation of internal storage includes a check that the capacity is not exceeded, and + +Capacity_Error is raised if this check fails. + +• In procedure Assign, if Source length is greater than Target capacity, then Capacity_Error is + +propagated. + +• The function Copy is replaced with: + + function Copy (Source : List; Capacity : Count_Type := 0) + return List; + +If Capacity is 0, then the list capacity is the length of Source; if Capacity is equal to or greater +than the length of Source, the list capacity equals the value of the Capacity parameter; otherwise, +the operation propagates Capacity_Error. + +• In the three-parameter procedure Splice whose Source has type List, if the sum of the length of +Target and the length of Source is greater than the capacity of Target, then Splice propagates +Capacity_Error. + +13/3 + +• In the four-parameter procedure Splice, if the length of Target equals the capacity of Target, + +then Splice propagates Capacity_Error. + +14/3 + +It is a bounded error to assign from a bounded list object while tampering with elements or cursors of that +object is prohibited. Either Program_Error is raised by the assignment, execution proceeds with the target +object prohibiting tampering with elements or cursors, or execution proceeds normally. + +Bounded (Run-Time) Errors + +A.18.19 The Generic Package Containers.Bounded_Vectors + +13 December 2012 560 + + Ada Reference Manual — 2012 Edition + +When a bounded list object L is finalized, if tampering with cursors is prohibited for L other than due to an +assignment from another list, then execution is erroneous. + +15/3 + +Erroneous Execution + +Implementation Requirements + +each + +instance + +For +of +Containers.Doubly_Linked_Lists +Containers.Bounded_Doubly_Linked_Lists, if the two instances meet the following conditions, then the +output generated by the List'Output or List'Write subprograms of either instance shall be readable by the +List'Input or List'Read of the other instance, respectively: + +instance + +each + +and + +of + +• + +• + +the Element_Type parameters of the two instances are statically matching subtypes of the same +type; and + +the output generated by Element_Type'Output or Element_Type'Write is readable by +Element_Type'Input or Element_Type'Read, respectively (where Element_Type denotes the +type of the two actual Element_Type parameters). + +Bounded list objects should be implemented without implicit pointers or dynamic allocation. + +The implementation advice for procedure Move to minimize copying does not apply. + +Implementation Advice + +A.18.21 The Generic Package Containers.Bounded_Hashed_Maps + +The language-defined generic package Containers.Bounded_Hashed_Maps provides a private type Map +and a set of operations. It provides the same operations as the package Containers.Hashed_Maps (see +A.18.5), with the difference that the maximum storage is bounded. + +Static Semantics + +The declaration of the generic library package Containers.Bounded_Hashed_Maps has the same contents +and semantics as Containers.Hashed_Maps except: + +• The pragma Preelaborate is replaced with pragma Pure. +• The type Map is declared with discriminants that specify both the capacity (number of elements) + +and modulus (number of distinct hash values) of the hash table as follows: + type Map (Capacity : Count_Type; + Modulus : Hash_Type) is tagged private; + +• The type Map needs finalization if and only if type Key_Type or type Element_Type needs + +finalization. + +• The description of Reserve_Capacity is replaced with: + +If the specified Capacity is larger than the capacity of Container, then Reserve_Capacity +propagates Capacity_Error. Otherwise, the operation has no effect. + +• An additional operation is added immediately following Reserve_Capacity: + + function Default_Modulus (Capacity : Count_Type) return Hash_Type; + +Default_Modulus returns an implementation-defined value for the number of distinct hash values +to be used for the given capacity (maximum number of elements). + +• The function Copy is replaced with: + + function Copy (Source : Map; + Capacity : Count_Type := 0; + Modulus : Hash_Type := 0) return Map; + +561 13 December 2012 + +The Generic Package Containers.Bounded_Doubly_Linked_Lists A.18.20 + +16/3 + +17/3 + +18/3 + +19/3 + +20/3 + +1/3 + +2/3 + +3/3 + +4/3 + +5/3 + +6/3 + +7/3 + +8/3 + +9/3 + +10/3 + +11/3 + +12/3 + +13/3 + + Ada Reference Manual — 2012 Edition + +14/3 + +Returns a map with key/element pairs initialized from the values in Source. If Capacity is 0, then +the map capacity is the length of Source; if Capacity is equal to or greater than the length of +Source, the map capacity is the value of the Capacity parameter; otherwise, the operation +propagates Capacity_Error. If the Modulus argument is 0, then the map modulus is the value +returned by a call to Default_Modulus with the map capacity as its argument; otherwise, the map +modulus is the value of the Modulus parameter. + +15/3 + +It is a bounded error to assign from a bounded map object while tampering with elements or cursors of that +object is prohibited. Either Program_Error is raised by the assignment, execution proceeds with the target +object prohibiting tampering with elements or cursors, or execution proceeds normally. + +Bounded (Run-Time) Errors + +16/3 + +When a bounded map object M is finalized, if tampering with cursors is prohibited for M other than due to +an assignment from another map, then execution is erroneous. + +Erroneous Execution + +Implementation Requirements + +17/3 + +18/3 + +19/3 + +20/3 + +For each instance of Containers.Hashed_Maps and each instance of Containers.Bounded_Hashed_Maps, if +the two instances meet the following conditions, then the output generated by the Map'Output or +Map'Write subprograms of either instance shall be readable by the Map'Input or Map'Read of the other +instance, respectively: + +• + +• + +• + +the Element_Type parameters of the two instances are statically matching subtypes of the same +type; and + +the output generated by Element_Type'Output or Element_Type'Write is readable by +Element_Type'Input or Element_Type'Read, respectively (where Element_Type denotes the +type of the two actual Element_Type parameters); and + +the preceding two conditions also hold for the Key_Type parameters of the instances. + +21/3 + +Bounded hashed map objects should be implemented without implicit pointers or dynamic allocation. + +22/3 + +The implementation advice for procedure Move to minimize copying does not apply. + +Implementation Advice + +A.18.22 The Generic Package Containers.Bounded_Ordered_Maps + +The language-defined generic package Containers.Bounded_Ordered_Maps provides a private type Map +and a set of operations. It provides the same operations as the package Containers.Ordered_Maps (see +A.18.6), with the difference that the maximum storage is bounded. + +Static Semantics + +The declaration of the generic library package Containers.Bounded_Ordered_Maps has the same contents +and semantics as Containers.Ordered_Maps except: + +• The pragma Preelaborate is replaced with pragma Pure. +• The type Map is declared with a discriminant that specifies the capacity (maximum number of + +elements) as follows: + type Map (Capacity : Count_Type) is tagged private; + +1/3 + +2/3 + +3/3 + +4/3 + +5/3 + +A.18.21 The Generic Package Containers.Bounded_Hashed_Maps + +13 December 2012 562 + + Ada Reference Manual — 2012 Edition + +• The type Map needs finalization if and only if type Key_Type or type Element_Type needs + +finalization. + +• The allocation of a new node includes a check that the capacity is not exceeded, and + +Capacity_Error is raised if this check fails. + +• In procedure Assign, if Source length is greater than Target capacity, then Capacity_Error is + +propagated. + +• The function Copy is replaced with: + + function Copy (Source : Map; + Capacity : Count_Type := 0) return Map; + +Returns a map with key/element pairs initialized from the values in Source. If Capacity is 0, then +the map capacity is the length of Source; if Capacity is equal to or greater than the length of +Source, the map capacity is the specified value; otherwise, the operation propagates +Capacity_Error. + +6/3 + +7/3 + +8/3 + +9/3 + +10/3 + +11/3 + +It is a bounded error to assign from a bounded map object while tampering with elements or cursors of that +object is prohibited. Either Program_Error is raised by the assignment, execution proceeds with the target +object prohibiting tampering with elements or cursors, or execution proceeds normally. + +12/3 + +Bounded (Run-Time) Errors + +When a bounded map object M is finalized, if tampering with cursors is prohibited for M other than due to +an assignment from another map, then execution is erroneous. + +13/3 + +Erroneous Execution + +Implementation Requirements + +For each instance of Containers.Ordered_Maps and each instance of Containers.Bounded_Ordered_Maps, +if the two instances meet the following conditions, then the output generated by the Map'Output or +Map'Write subprograms of either instance shall be readable by the Map'Input or Map'Read of the other +instance, respectively: + +• + +• + +• + +the Element_Type parameters of the two instances are statically matching subtypes of the same +type; and + +the output generated by Element_Type'Output or Element_Type'Write is readable by +Element_Type'Input or Element_Type'Read, respectively (where Element_Type denotes the +type of the two actual Element_Type parameters); and + +the preceding two conditions also hold for the Key_Type parameters of the instances. + +Bounded ordered map objects should be implemented without implicit pointers or dynamic allocation. + +The implementation advice for procedure Move to minimize copying does not apply. + +Implementation Advice + +A.18.23 The Generic Package Containers.Bounded_Hashed_Sets + +The language-defined generic package Containers.Bounded_Hashed_Sets provides a private type Set and +a set of operations. It provides the same operations as the package Containers.Hashed_Sets (see A.18.8), +with the difference that the maximum storage is bounded. + +14/3 + +15/3 + +16/3 + +17/3 + +18/3 + +19/3 + +1/3 + +563 13 December 2012 + +The Generic Package Containers.Bounded_Ordered_Maps A.18.22 + + Ada Reference Manual — 2012 Edition + +2/3 + +3/3 + +4/3 + +5/3 + +6/3 + +7/3 + +8/3 + +9/3 + +10/3 + +11/3 + +12/3 + +13/3 + +14/3 + +Static Semantics + +The declaration of the generic library package Containers.Bounded_Hashed_Sets has the same contents +and semantics as Containers.Hashed_Sets except: + +• The pragma Preelaborate is replaced with pragma Pure. +• The type Set is declared with discriminants that specify both the capacity (number of elements) + +and modulus (number of distinct hash values) of the hash table as follows: + type Set (Capacity : Count_Type; + Modulus : Hash_Type) is tagged private; + +• The type Set needs finalization if and only if type Element_Type needs finalization. +• The description of Reserve_Capacity is replaced with: + +If the specified Capacity is larger than the capacity of Container, then Reserve_Capacity +propagates Capacity_Error. Otherwise, the operation has no effect. + +• An additional operation is added immediately following Reserve_Capacity: + + function Default_Modulus (Capacity : Count_Type) return Hash_Type; + +Default_Modulus returns an implementation-defined value for the number of distinct hash values +to be used for the given capacity (maximum number of elements). + +• The function Copy is replaced with: + + function Copy (Source : Set; + Capacity : Count_Type := 0; + Modulus : Hash_Type := 0) return Set; + +Returns a set whose elements are initialized from the values in Source. If Capacity is 0, then the +set capacity is the length of Source; if Capacity is equal to or greater than the length of Source, +the set capacity is the value of the Capacity parameter; otherwise, the operation propagates +Capacity_Error. If the Modulus argument is 0, then the set modulus is the value returned by a +call to Default_Modulus with the set capacity as its argument; otherwise, the set modulus is the +value of the Modulus parameter. + +15/3 + +It is a bounded error to assign from a bounded set object while tampering with elements or cursors of that +object is prohibited. Either Program_Error is raised by the assignment, execution proceeds with the target +object prohibiting tampering with elements or cursors, or execution proceeds normally. + +Bounded (Run-Time) Errors + +16/3 + +When a bounded set object S is finalized, if tampering with cursors is prohibited for S other than due to an +assignment from another set, then execution is erroneous. + +Erroneous Execution + +Implementation Requirements + +17/3 + +18/3 + +19/3 + +For each instance of Containers.Hashed_Sets and each instance of Containers.Bounded_Hashed_Sets, if +the two instances meet the following conditions, then the output generated by the Set'Output or Set'Write +subprograms of either instance shall be readable by the Set'Input or Set'Read of the other instance, +respectively: + +• + +• + +the Element_Type parameters of the two instances are statically matching subtypes of the same +type; and + +the output generated by Element_Type'Output or Element_Type'Write is readable by +Element_Type'Input or Element_Type'Read, respectively (where Element_Type denotes the +type of the two actual Element_Type parameters). + +A.18.23 The Generic Package Containers.Bounded_Hashed_Sets + +13 December 2012 564 + + Ada Reference Manual — 2012 Edition + +Bounded hashed set objects should be implemented without implicit pointers or dynamic allocation. + +The implementation advice for procedure Move to minimize copying does not apply. + +Implementation Advice + +A.18.24 The Generic Package Containers.Bounded_Ordered_Sets + +The language-defined generic package Containers.Bounded_Ordered_Sets provides a private type Set and +a set of operations. It provides the same operations as the package Containers.Ordered_Sets (see A.18.9), +with the difference that the maximum storage is bounded. + +Static Semantics + +The declaration of the generic library package Containers.Bounded_Ordered_Sets has the same contents +and semantics as Containers.Ordered_Sets except: + +• The pragma Preelaborate is replaced with pragma Pure. +• The type Set is declared with a discriminant that specifies the capacity (maximum number of + +elements) as follows: + type Set (Capacity : Count_Type) is tagged private; + +• The type Set needs finalization if and only if type Element_Type needs finalization. +• If Insert (or Include) adds an element, a check is made that the capacity is not exceeded, and + +Capacity_Error is raised if this check fails. + +• In procedure Assign, if Source length is greater than Target capacity, then Capacity_Error is + +propagated. + +• The function Copy is replaced with: + + function Copy (Source : Set; + Capacity : Count_Type := 0) return Set; + +Returns a set whose elements are initialized from the values in Source. If Capacity is 0, then the +set capacity is the length of Source; if Capacity is equal to or greater than the length of Source, +the set capacity is the specified value; otherwise, the operation propagates Capacity_Error. + +20/3 + +21/3 + +1/3 + +2/3 + +3/3 + +4/3 + +5/3 + +6/3 + +7/3 + +8/3 + +9/3 + +10/3 + +11/3 + +It is a bounded error to assign from a bounded set object while tampering with elements or cursors of that +object is prohibited. Either Program_Error is raised by the assignment, execution proceeds with the target +object prohibiting tampering with elements or cursors, or execution proceeds normally. + +12/3 + +Bounded (Run-Time) Errors + +When a bounded set object S is finalized, if tampering with cursors is prohibited for S other than due to an +assignment from another set, then execution is erroneous. + +13/3 + +Erroneous Execution + +Implementation Requirements + +For each instance of Containers.Ordered_Sets and each instance of Containers.Bounded_Ordered_Sets, if +the two instances meet the following conditions, then the output generated by the Set'Output or Set'Write +subprograms of either instance shall be readable by the Set'Input or Set'Read of the other instance, +respectively: + +• + +the Element_Type parameters of the two instances are statically matching subtypes of the same +type; and + +14/3 + +15/3 + +565 13 December 2012 + +The Generic Package Containers.Bounded_Hashed_Sets A.18.23 + + Ada Reference Manual — 2012 Edition + +16/3 + +• + +the output generated by Element_Type'Output or Element_Type'Write is readable by +Element_Type'Input or Element_Type'Read, respectively (where Element_Type denotes the +type of the two actual Element_Type parameters). + +17/3 + +Bounded ordered set objects should be implemented without implicit pointers or dynamic allocation. + +18/3 + +The implementation advice for procedure Move to minimize copying does not apply. + +Implementation Advice + +1/3 + +2/3 + +3/3 + +4/3 + +5/3 + +6/3 + +7/3 + +8/3 + +9/3 + +10/3 + +11/3 + +12/3 + +13/3 + +14/3 + +A.18.25 The Generic Package Containers.Bounded_Multiway_Trees + +The language-defined generic package Containers.Bounded_Multiway_Trees provides a private type Tree +and a set of operations. It provides the same operations as the package Containers.Multiway_Trees (see +A.18.10), with the difference that the maximum storage is bounded. + +Static Semantics + +The declaration of the generic library package Containers.Bounded_Multiway_Trees has the same +contents and semantics as Containers.Multiway_Trees except: +• The pragma Preelaborate is replaced with pragma Pure. +• The type Tree is declared with a discriminant that specifies the capacity (maximum number of + +elements) as follows: + type Tree (Capacity : Count_Type) is tagged private; + +• The type Tree needs finalization if and only if type Element_Type needs finalization. +• The allocation of internal storage includes a check that the capacity is not exceeded, and + +Capacity_Error is raised if this check fails. + +• In procedure Assign, if Source length is greater than Target capacity, then Capacity_Error is + +propagated. + +• Function Copy is declared as follows: + + function Copy (Source : Tree; Capacity : Count_Type := 0) + return List; + +If Capacity is 0, then the tree capacity is the count of Source; if Capacity is equal to or greater +than Source.Count, the tree capacity equals the value of the Capacity parameter; otherwise, the +operation propagates Capacity_Error. + +• In the five-parameter procedure Splice_Subtree, if Source is not the same object as Target, and if +the sum of Target.Count and Subtree_Node_Count (Position) is greater than Target.Capacity, +then Splice_Subtree propagates Capacity_Error. + +• In the five-parameter procedure Splice_Children, if Source is not the same object as Target, and +if the sum of Target.Count and Subtree_Node_Count (Source_Parent)-1 is greater than +Target.Capacity, then Splice_Children propagates Capacity_Error. + +It is a bounded error to assign from a bounded tree object while tampering with elements or cursors of that +object is prohibited. Either Program_Error is raised by the assignment, execution proceeds with the target +object prohibiting tampering with elements or cursors, or execution proceeds normally. + +Bounded (Run-Time) Errors + +A.18.24 The Generic Package Containers.Bounded_Ordered_Sets + +13 December 2012 566 + + + Ada Reference Manual — 2012 Edition + +When a bounded tree object T is finalized, if tampering with cursors is prohibited for T other than due to +an assignment from another tree, then execution is erroneous. + +15/3 + +Erroneous Execution + +Implementation Requirements + +16/3 + +17/3 + +18/3 + +19/3 + +20/3 + +each + +instance + +For +of +Containers.Multiway_Trees +Containers.Bounded_Multiway_Trees, if the two instances meet the following conditions, then the output +generated by the Tree'Output or Tree'Write subprograms of either instance shall be readable by the +Tree'Input or Tree'Read of the other instance, respectively: + +instance + +each + +and + +of + +• + +• + +the Element_Type parameters of the two instances are statically matching subtypes of the same +type; and + +the output generated by Element_Type'Output or Element_Type'Write is readable by +Element_Type'Input or Element_Type'Read, respectively (where Element_Type denotes the +type of the two actual Element_Type parameters). + +Bounded tree objects should be implemented without implicit pointers or dynamic allocation. + +The implementation advice for procedure Move to minimize copying does not apply. + +Implementation Advice + +567 13 December 2012 + +The Generic Package Containers.Bounded_Multiway_Trees A.18.25 + + Ada Reference Manual — 2012 Edition + +A.18.26 Array Sorting + +1/3 + +language-defined generic procedures Containers.Generic_Array_Sort, Containers.Generic_- + +The +Constrained_Array_Sort, and Containers.Generic_Sort provide sorting on arbitrary array types. + +2/2 + +3/2 + +4/2 + +5/3 + +6/2 + +7/2 + +8/2 + +9/3 + +The generic library procedure Containers.Generic_Array_Sort has the following declaration: + +Static Semantics + +generic + type Index_Type is (<>); + type Element_Type is private; + type Array_Type is array (Index_Type range <>) of Element_Type; + with function "<" (Left, Right : Element_Type) + return Boolean is <>; +procedure Ada.Containers.Generic_Array_Sort (Container : in out Array_Type); +pragma Pure(Ada.Containers.Generic_Array_Sort); + +Reorders the elements of Container such that the elements are sorted smallest first as determined +by the generic formal "<" operator provided. Any exception raised during evaluation of "<" is +propagated. + +The actual function for the generic formal function "<" of Generic_Array_Sort is expected to +return the same value each time it is called with a particular pair of element values. It should +define a strict weak ordering relationship (see A.18); it should not modify Container. If the +instance of +actual for "<" behaves +Generic_Array_Sort is unspecified. The number of times Generic_Array_Sort calls "<" is +unspecified. + +in some other manner, + +the behavior of + +the + +The generic library procedure Containers.Generic_Constrained_Array_Sort has the following declaration: + +generic + type Index_Type is (<>); + type Element_Type is private; + type Array_Type is array (Index_Type) of Element_Type; + with function "<" (Left, Right : Element_Type) + return Boolean is <>; +procedure Ada.Containers.Generic_Constrained_Array_Sort + (Container : in out Array_Type); +pragma Pure(Ada.Containers.Generic_Constrained_Array_Sort); + +Reorders the elements of Container such that the elements are sorted smallest first as determined +by the generic formal "<" operator provided. Any exception raised during evaluation of "<" is +propagated. + +The actual function for the generic formal function "<" of Generic_Constrained_Array_Sort is +expected to return the same value each time it is called with a particular pair of element values. +It should define a strict weak ordering relationship (see A.18); it should not modify Container. If +the actual for "<" behaves in some other manner, the behavior of the instance of +Generic_Constrained_Array_Sort +times +unspecified. +Generic_Constrained_Array_Sort calls "<" is unspecified. + +number + +The + +of + +is + +9.1/3 + +9.2/3 + +The generic library procedure Containers.Generic_Sort has the following declaration: + +generic + type Index_Type is (<>); + with function Before (Left, Right : Index_Type) return Boolean; + with procedure Swap (Left, Right : Index_Type); +procedure Ada.Containers.Generic_Sort + (First, Last : Index_Type'Base); +pragma Pure(Ada.Containers.Generic_Sort); + +A.18.26 Array Sorting + +13 December 2012 568 + + Ada Reference Manual — 2012 Edition + +Reorders the elements of an indexable structure, over the range First .. Last, such that the +elements are sorted in the ordering determined by the generic formal function Before; Before +should return True if Left is to be sorted before Right. The generic formal Before compares the +elements having the given indices, and the generic formal Swap exchanges the values of the +indicated elements. Any exception raised during evaluation of Before or Swap is propagated. + +The actual function for the generic formal function Before of Generic_Sort is expected to return +the same value each time it is called with index values that identify a particular pair of element +values. It should define a strict weak ordering relationship (see A.18); it should not modify the +elements. The actual function for the generic formal Swap should exchange the values of the +indicated elements. If the actual for either Before or Swap behaves in some other manner, the +behavior of Generic_Sort is unspecified. The number of times the Generic_Sort calls Before or +Swap is unspecified. + +9.3/3 + +9.4/3 + +Implementation Advice + +The worst-case time complexity of a call on an instance of Containers.Generic_Array_Sort or +Containers.Generic_Constrained_Array_Sort should be O(N**2) or better, and the average time +complexity should be better than O(N**2), where N is the length of the Container parameter. + +10/2 + +Containers.Generic_Array_Sort and Containers.Generic_Constrained_Array_Sort +copying of elements. + +should minimize + +11/2 + +The worst-case time complexity of a call on an instance of Containers.Generic_Sort should be O(N**2) or +better, and the average time complexity should be better than O(N**2), where N is the difference between +the Last and First parameters plus 1. + +Containers.Generic_Sort should minimize calls to the generic formal Swap. + +12/3 + +13/3 + +A.18.27 The Generic Package +Containers.Synchronized_Queue_Interfaces + +The language-defined generic package Containers.Synchronized_Queue_Interfaces provides interface type +Queue, and a set of operations for that type. Interface Queue specifies a first-in, first-out queue. + +1/3 + +The generic library package Containers.Synchronized_Queue_Interfaces has the following declaration: + +Static Semantics + +generic + type Element_Type is private; +package Ada.Containers.Synchronized_Queue_Interfaces is + pragma Pure(Synchronized_Queue_Interfaces); + type Queue is synchronized interface; + procedure Enqueue + (Container : in out Queue; + New_Item : in Element_Type) is abstract + with Synchronization => By_Entry; + procedure Dequeue + (Container : in out Queue; + Element : out Element_Type) is abstract + with Synchronization => By_Entry; + function Current_Use (Container : Queue) return Count_Type is abstract; + function Peak_Use (Container : Queue) return Count_Type is abstract; +end Ada.Containers.Synchronized_Queue_Interfaces; + +2/3 + +3/3 + +4/3 + +5/3 + +6/3 + +7/3 + +8/3 + +569 13 December 2012 + +Array Sorting A.18.26 + + 9/3 + +10/3 + +11/3 + +12/3 + +13/3 + +14/3 + +15/3 + +16/3 + +17/3 + +1/3 + +2/3 + +3/3 + +4/3 + +5/3 + +6/3 + +Ada Reference Manual — 2012 Edition + +procedure Enqueue + (Container : in out Queue; + New_Item : in Element_Type) is abstract; + +A queue type that implements this interface is allowed to have a bounded capacity. If the queue +object has a bounded capacity, and the number of existing elements equals the capacity, then +Enqueue blocks until storage becomes available; otherwise, Enqueue does not block. In any +case, it then copies New_Item onto the queue. + +procedure Dequeue + (Container : in out Queue; + Element : out Element_Type) is abstract; + +If the queue is empty, then Dequeue blocks until an item becomes available. In any case, it then +assigns the element at the head of the queue to Element, and removes it from the queue. + +function Current_Use (Container : Queue) return Count_Type is abstract; + +Returns the number of elements currently in the queue. + +function Peak_Use (Container : Queue) return Count_Type is abstract; + +Returns the maximum number of elements that have been in the queue at any one time. + +NOTES +51 Unlike other language-defined containers, there are no queues whose element types are indefinite. Elements of an +indefinite type can be handled by defining the element of the queue to be a holder container (see A.18.18) of the indefinite +type, or to be an explicit access type that designates the indefinite type. + +A.18.28 The Generic Package +Containers.Unbounded_Synchronized_Queues + +Static Semantics + +The language-defined generic package Containers.Unbounded_Synchronized_Queues provides type +Queue, which implements the interface type Containers.Synchronized_Queue_Interfaces.Queue. + +with System; +with Ada.Containers.Synchronized_Queue_Interfaces; +generic + with package Queue_Interfaces is new +Ada.Containers.Synchronized_Queue_Interfaces (<>); + Default_Ceiling : System.Any_Priority := System.Priority'Last; +package Ada.Containers.Unbounded_Synchronized_Queues is + pragma Preelaborate(Unbounded_Synchronized_Queues); + package Implementation is + ... -- not specified by the language + end Implementation; + protected type Queue + (Ceiling : System.Any_Priority := Default_Ceiling) + with Priority => Ceiling is + new Queue_Interfaces.Queue with + overriding + entry Enqueue (New_Item : in Queue_Interfaces.Element_Type); + overriding + entry Dequeue (Element : out Queue_Interfaces.Element_Type); + overriding + function Current_Use return Count_Type; + overriding + function Peak_Use return Count_Type; + +A.18.27 The Generic Package Containers.Synchronized_Queue_Interfaces + +13 December 2012 570 + + Ada Reference Manual — 2012 Edition + + private + ... -- not specified by the language + end Queue; +private + ... -- not specified by the language +end Ada.Containers.Unbounded_Synchronized_Queues; + +The type Queue is used to represent task-safe queues. + +The capacity for instances of type Queue is unbounded. + +A.18.29 The Generic Package +Containers.Bounded_Synchronized_Queues + +Static Semantics + +The language-defined generic package Containers.Bounded_Synchronized_Queues provides type Queue, +which implements the interface type Containers.Synchronized_Queue_Interfaces.Queue. + +with System; +with Ada.Containers.Synchronized_Queue_Interfaces; +generic + with package Queue_Interfaces is new +Ada.Containers.Synchronized_Queue_Interfaces (<>); + Default_Capacity : Count_Type; + Default_Ceiling : System.Any_Priority := System.Priority'Last; +package Ada.Containers.Bounded_Synchronized_Queues is + pragma Preelaborate(Bounded_Synchronized_Queues); + package Implementation is + ... -- not specified by the language + end Implementation; + protected type Queue + (Capacity : Count_Type := Default_Capacity; + Ceiling : System.Any_Priority := Default_Ceiling) + with Priority => Ceiling is + new Queue_Interfaces.Queue with + overriding + entry Enqueue (New_Item : in Queue_Interfaces.Element_Type); + overriding + entry Dequeue (Element : out Queue_Interfaces.Element_Type); + overriding + function Current_Use return Count_Type; + overriding + function Peak_Use return Count_Type; + private + ... -- not specified by the language + end Queue; +private + ... -- not specified by the language +end Ada.Containers.Bounded_Synchronized_Queues; + +The semantics are the same as for Unbounded_Synchronized_Queues, except: + +• The capacity for instances of type Queue is bounded and specified by the discriminant Capacity. + +Bounded queue objects should be implemented without implicit pointers or dynamic allocation. + +Implementation Advice + +571 13 December 2012 + +The Generic Package Containers.Unbounded_Synchronized_Queues A.18.28 + +7/3 + +8/3 + +9/3 + +10/3 + +11/3 + +12/3 + +1/3 + +2/3 + +3/3 + +4/3 + +5/3 + +6/3 + +7/3 + +8/3 + +9/3 + +10/3 + +11/3 + +12/3 + +13/3 + + Ada Reference Manual — 2012 Edition + +A.18.30 The Generic Package Containers.Unbounded_Priority_Queues + +The language-defined generic package Containers.Unbounded_Priority_Queues provides type Queue, +which implements the interface type Containers.Synchronized_Queue_Interfaces.Queue. + +Static Semantics + +with System; +with Ada.Containers.Synchronized_Queue_Interfaces; +generic + with package Queue_Interfaces is new +Ada.Containers.Synchronized_Queue_Interfaces (<>); + type Queue_Priority is private; + with function Get_Priority + (Element : Queue_Interfaces.Element_Type) return Queue_Priority is <>; + with function Before + (Left, Right : Queue_Priority) return Boolean is <>; + Default_Ceiling : System.Any_Priority := System.Priority'Last; +package Ada.Containers.Unbounded_Priority_Queues is + pragma Preelaborate(Unbounded_Priority_Queues); + package Implementation is + ... -- not specified by the language + end Implementation; + protected type Queue + (Ceiling : System.Any_Priority := Default_Ceiling) + with Priority => Ceiling is + new Queue_Interfaces.Queue with + overriding + entry Enqueue (New_Item : in Queue_Interfaces.Element_Type); + overriding + entry Dequeue (Element : out Queue_Interfaces.Element_Type); + not overriding + procedure Dequeue_Only_High_Priority + (At_Least : in Queue_Priority; + Element : in out Queue_Interfaces.Element_Type; + Success : out Boolean); + overriding + function Current_Use return Count_Type; + overriding + function Peak_Use return Count_Type; + private + ... -- not specified by the language + end Queue; +private + ... -- not specified by the language +end Ada.Containers.Unbounded_Priority_Queues; + +The type Queue is used to represent task-safe priority queues. + +1/3 + +2/3 + +3/3 + +4/3 + +5/3 + +6/3 + +7/3 + +8/3 + +9/3 + +10/3 + +11/3 + +12/3 + +13/3 + +The capacity for instances of type Queue is unbounded. + +14/3 + +15/3 + +Two elements E1 and E2 are equivalent +Before(Get_Priority(E2), Get_Priority(E1)) both return False. + +if Before(Get_Priority(E1), Get_Priority(E2)) and + +The actual functions for Get_Priority and Before are expected to return the same value each time they are +called with the same actuals, and should not modify their actuals. Before should define a strict weak +ordering relationship (see A.18). If the actual functions behave in some other manner, the behavior of +Unbounded_Priority_Queues is unspecified. + +A.18.30 The Generic Package Containers.Unbounded_Priority_Queues + +13 December 2012 572 + + Ada Reference Manual — 2012 Edition + +Enqueue inserts an item according to the order specified by the Before function on the result of +Get_Priority on the elements; Before should return True if Left is to be inserted before Right. If the queue +already contains elements equivalent to New_Item, then it is inserted after the existing equivalent +elements. + +For a call on Dequeue_Only_High_Priority, if the head of the nonempty queue is E, and the function +Before(At_Least, Get_Priority(E)) returns False, then E is assigned to Element and then removed from the +queue, and Success is set to True; otherwise, Success is set to False and Element is unchanged. + +A.18.31 The Generic Package Containers.Bounded_Priority_Queues + +The language-defined generic package Containers.Bounded_Priority_Queues provides type Queue, which +implements the interface type Containers.Synchronized_Queue_Interfaces.Queue. + +Static Semantics + +with System; +with Ada.Containers.Synchronized_Queue_Interfaces; +generic + with package Queue_Interfaces is new +Ada.Containers.Synchronized_Queue_Interfaces (<>); + type Queue_Priority is private; + with function Get_Priority + (Element : Queue_Interfaces.Element_Type) return Queue_Priority is <>; + with function Before + (Left, Right : Queue_Priority) return Boolean is <>; + Default_Capacity : Count_Type; + Default_Ceiling : System.Any_Priority := System.Priority'Last; +package Ada.Containers.Bounded_Priority_Queues is + pragma Preelaborate(Bounded_Priority_Queues); + package Implementation is + ... -- not specified by the language + end Implementation; + protected type Queue + (Capacity : Count_Type := Default_Capacity; + Ceiling : System.Any_Priority := Default_Ceiling) + with Priority => Ceiling is + new Queue_Interfaces.Queue with + overriding + entry Enqueue (New_Item : in Queue_Interfaces.Element_Type); + overriding + entry Dequeue (Element : out Queue_Interfaces.Element_Type); + not overriding + procedure Dequeue_Only_High_Priority + (At_Least : in Queue_Priority; + Element : in out Queue_Interfaces.Element_Type; + Success : out Boolean); + overriding + function Current_Use return Count_Type; + overriding + function Peak_Use return Count_Type; + private + ... -- not specified by the language + end Queue; +private + ... -- not specified by the language +end Ada.Containers.Bounded_Priority_Queues; + +16/3 + +17/3 + +1/3 + +2/3 + +3/3 + +4/3 + +5/3 + +6/3 + +7/3 + +8/3 + +9/3 + +10/3 + +11/3 + +573 13 December 2012 + +The Generic Package Containers.Unbounded_Priority_Queues A.18.30 + + Ada Reference Manual — 2012 Edition + +12/3 + +13/3 + +The semantics are the same as for Unbounded_Priority_Queues, except: + +• The capacity for instances of type Queue is bounded and specified by the discriminant Capacity. + +14/3 + +Bounded priority queue objects should be implemented without implicit pointers or dynamic allocation. + +Implementation Advice + +A.18.32 Example of Container Use + +Examples + +The following example is an implementation of Dijkstra's shortest path algorithm in a directed graph with +positive distances. The graph is represented by a map from nodes to sets of edges. + +with Ada.Containers.Vectors; +with Ada.Containers.Doubly_Linked_Lists; +use Ada.Containers; +generic + type Node is range <>; +package Shortest_Paths is + type Distance is new Float range 0.0 .. Float'Last; + type Edge is record + To, From : Node; + Length : Distance; + end record; + package Node_Maps is new Vectors (Node, Node); + -- The algorithm builds a map to indicate the node used to reach a given + -- node in the shortest distance. + package Adjacency_Lists is new Doubly_Linked_Lists (Edge); + use Adjacency_Lists; + package Graphs is new Vectors (Node, Adjacency_Lists.List); + package Paths is new Doubly_Linked_Lists (Node); + function Shortest_Path + (G : Graphs.Vector; Source : Node; Target : Node) return Paths.List + with Pre => G (Source) /= Adjacency_Lists.Empty_List; +end Shortest_Paths; +package body Shortest_Paths is + function Shortest_Path + (G : Graphs.Vector; Source : Node; Target : Node) return Paths.List + is + use Adjacency_Lists, Node_Maps, Paths, Graphs; + Reached : array (Node) of Boolean := (others => False); + -- The set of nodes whose shortest distance to the source is known. + Reached_From : array (Node) of Node; + So_Far : array (Node) of Distance := (others => Distance'Last); + The_Path : Paths.List := Paths.Empty_List; + Nearest_Distance : Distance; + Next : Node; + begin + So_Far(Source) := 0.0; + while not Reached(Target) loop + Nearest_Distance := Distance'Last; + -- Find closest node not reached yet, by iterating over all nodes. + -- A more efficient algorithm uses a priority queue for this step. + +1/3 + +2/3 + +3/3 + +4/3 + +5/3 + +6/3 + +7/3 + +8/3 + +9/3 + +10/3 + +11/3 + +12/3 + +A.18.31 The Generic Package Containers.Bounded_Priority_Queues + +13 December 2012 574 + + Ada Reference Manual — 2012 Edition + + Next := Source; + for N in Node'First .. Node'Last loop + if not Reached(N) + and then So_Far(N) < Nearest_Distance then + Next := N; + Nearest_Distance := So_Far(N); + end if; + end loop; + if Nearest_Distance = Distance'Last then + -- No next node found, graph is not connected + return Paths.Empty_List; + else + Reached(Next) := True; + end if; + -- Update minimum distance to newly reachable nodes. + for E of G (Next) loop + if not Reached(E.To) then + Nearest_Distance := E.Length + So_Far(Next); + if Nearest_Distance < So_Far(E.To) then + Reached_From(E.To) := Next; + So_Far(E.To) := Nearest_Distance; + end if; + end if; + end loop; + end loop; + -- Rebuild path from target to source. + declare + N : Node := Target; + begin + while N /= Source loop + N := Reached_From(N); + Prepend (The_Path, N); + end loop; + end; + return The_Path; + end; +end Shortest_Paths; + +Note that the effect of the Constant_Indexing aspect (on type Vector) and the Implicit_Dereference aspect +(on type Reference_Type) is that + +G (Next) + +is a convenient short hand for + +G.Constant_Reference (Next).Element.all + +Similarly, the effect of the loop: + +for E of G (Next) loop + if not Reached(E.To) then + ... + end if; +end loop; + +13/3 + +14/3 + +15/3 + +16/3 + +17/3 + +18/3 + +19/3 + +20/3 + +21/3 + +22/3 + +23/3 + +24/3 + +25/3 + +26/3 + +27/3 + +575 13 December 2012 + +Example of Container Use A.18.32 + + Ada Reference Manual — 2012 Edition + +28/3 + +29/3 + +30/3 + +31/3 + +is the same as: + +for C in G (Next).Iterate loop + declare + E : Edge renames G (Next)(C).all; + begin + if not Reached(E.To) then + ... + end if; + end; +end loop; + +which is the same as: +declare + L : Adjacency_Lists.List renames G (Next); + C : Adjacency_Lists.Cursor := L.First; +begin + while Has_Element (C) loop + declare + E : Edge renames L(C).all; + begin + if not Reached(E.To) then + ... + end if; + end; + C := L.Next (C); + end loop; +end; + +A.19 The Package Locales + +1/3 + +A locale identifies a geopolitical place or region and its associated language, which can be used to +determine other internationalization-related characteristics. + +2/3 + +3/3 + +4/3 + +5/3 + +6/3 + +7/3 + +8/3 + +9/3 + +10/3 + +11/3 + +The library package Locales has the following declaration: + +Static Semantics + +package Ada.Locales is + pragma Preelaborate(Locales); + pragma Remote_Types(Locales); + type Language_Code is array (1 .. 3) of Character range 'a' .. 'z'; + type Country_Code is array (1 .. 2) of Character range 'A' .. 'Z'; + Language_Unknown : constant Language_Code := "und"; + Country_Unknown : constant Country_Code := "ZZ"; + function Language return Language_Code; + function Country return Country_Code; +end Ada.Locales; + +The active locale is the locale associated with the partition of the current task. + +Language_Code is a lower-case string representation of an ISO 639-3 alpha-3 code that identifies a +language. + +Country_Code is an upper-case string representation of an ISO 3166-1 alpha-2 code that identifies a +country. + +Function Language returns the code of the language associated with the active locale. If the +Language_Code associated with the active locale cannot be determined from the environment, then +Language returns Language_Unknown. + +A.18.32 Example of Container Use + +13 December 2012 576 + + Function Country returns the code of the country associated with the active locale. If the Country_Code +associated with the active locale cannot be determined from the environment, then Country returns +Country_Unknown. + +12/3 + +Ada Reference Manual — 2012 Edition + +577 13 December 2012 + +The Package Locales A.19 + + Ada Reference Manual — 2012 Edition + +Annex B +(normative) +Interface to Other Languages + +This Annex describes features for writing mixed-language programs. General interface support is +presented first; then specific support for C, COBOL, and Fortran is defined, in terms of language interface +packages for each of these languages. + +Implementation Requirements + +Support for interfacing to any foreign language is optional. However, an implementation shall not provide +any optional aspect, attribute, library unit, or pragma having the same name as an aspect, attribute, library +unit, or pragma (respectively) specified in the subclauses of this Annex unless the provided construct is +either as specified in those subclauses or is more limited in capability than that required by those +subclauses. A program that attempts to use an unsupported capability of this Annex shall either be +identified by the implementation before run time or shall raise an exception at run time. + +B.1 Interfacing Aspects + +An interfacing aspect is a representation aspect that is one of the aspects Import, Export, Link_Name, +External_Name, or Convention. + +Specifying the Import aspect to have the value True is used to import an entity defined in a foreign +language into an Ada program, thus allowing a foreign-language subprogram to be called from Ada, or a +foreign-language variable to be accessed from Ada. In contrast, specifying the Export aspect to have the +value True is used to export an Ada entity to a foreign language, thus allowing an Ada subprogram to be +called from a foreign language, or an Ada object to be accessed from a foreign language. The Import and +Export aspects are intended primarily for objects and subprograms, although implementations are allowed +to support other entities. The Link_Name and External_Name aspects are used to specify the link name +and external name, respectively, to be used to identify imported or exported entities in the external +environment. + +1 + +2/3 + +0.1/3 + +1/3 + +The Convention aspect is used to indicate that an Ada entity should use the conventions of another +language. It is intended primarily for types and “callback” subprograms. For example, “with Convention +=> Fortran” on the declaration of an array type Matrix implies that Matrix should be represented according +to the conventions of the supported Fortran implementation, namely column-major order. + +2/3 + +A pragma Linker_Options is used to specify the system linker parameters needed when a given +compilation unit is included in a partition. + +3 + +The form of a pragma Linker_Options is as follows: +Paragraphs 5 through 7 were moved to Annex J, “Obsolescent Features”. + + pragma Linker_Options(string_expression); + +Syntax + +A pragma Linker_Options is allowed only at the place of a declarative_item. + +This paragraph was deleted. + +4/3 + +8 + +9 + +9.1/3 + +579 13 December 2012 + +Interface to Other Languages B + + Ada Reference Manual — 2012 Edition + +9.2/3 + +The Import and Export aspects are of type Boolean. + +10/3 + +The Link_Name and External_Name aspects are of type String. + +Name Resolution Rules + +10.1/3 + +The expected type for the string_expression in pragma Linker_Options is String. + +11/3 + +12 + +13 + +14/3 + +15 + +16 + +17/3 + +18 + +19 + +20 + +21/3 + +22/3 + +23/3 + +24 + +25/3 + +26/3 + +27/3 + +Legality Rules + +The aspect Convention shall be specified by a convention_identifier which shall be the name of a +convention. The convention names are implementation defined, except for certain language-defined ones, +such as Ada and Intrinsic, as explained in 6.3.1, “Conformance Rules”. Additional convention names +generally represent the calling conventions of foreign languages, language implementations, or specific +run-time models. The convention of a callable entity is its calling convention. + +If L is a convention_identifier for a language, then a type T is said to be compatible with convention L, +(alternatively, is said to be an L-compatible type) if any of the following conditions are met: + +• T is declared in a language interface package corresponding to L and is defined to be L- + +compatible (see B.3, B.3.1, B.3.2, B.4, B.5), + +• Convention L has been specified for T, and T is eligible for convention L; that is: + +• T is an array type with either an unconstrained or statically-constrained first subtype, and + +its component type is L-compatible, + +• T is a record type that has no discriminants and that only has components with statically- + +constrained subtypes, and each component type is L-compatible, + +• T is an access-to-object type, its designated type is L-compatible, and its designated + +subtype is not an unconstrained array subtype, + +• T is an access-to-subprogram type, and its designated profile's parameter and result types + +are all L-compatible. + +• T is derived from an L-compatible type, +• The implementation permits T as an L-compatible type. + +If the Convention aspect is specified for a type, then the type shall either be compatible with or eligible for +the specified convention. + +Notwithstanding any rule to the contrary, a declaration with a True Import aspect shall not have a +completion. + + An entity with a True Import aspect (or Export aspect) is said to be imported (respectively, exported). An +entity shall not be both imported and exported. + +The declaration of an imported object shall not include an explicit initialization expression. Default +initializations are not performed. + +The type of an imported or exported object shall be compatible with the specified Convention aspect, if +any. + +For an imported or exported subprogram, the result and parameter types shall each be compatible with the +specified Convention aspect, if any. + +The aspect_definition (if any) used to directly specify an Import, Export, External_Name, or Link_Name +aspect shall be a static expression. The string_expression of a pragma Linker_Options shall be static. An + +B.1 Interfacing Aspects + +13 December 2012 580 + + Ada Reference Manual — 2012 Edition + +External_Name or Link_Name aspect shall be specified only for an entity that is either imported or +exported. + +Paragraphs 28 and 29 were deleted. + +Static Semantics + +The Convention aspect represents the calling convention or representation convention of the entity. For an +access-to-subprogram type, it represents the calling convention of designated subprograms. In addition: +• A True Import aspect indicates that the entity is defined externally (that is, outside the Ada +program). This aspect is never inherited; if not directly specified, the Import aspect is False. +• A True Export aspect indicates that the entity is used externally. This aspect is never inherited; if + +not directly specified, the Export aspect is False. + +• For an entity with a True Import or Export aspect, an external name, link name, or both may also + +be specified. + +An external name is a string value for the name used by a foreign language program either for an entity +that an Ada program imports, or for referring to an entity that an Ada program exports. + +A link name is a string value for the name of an exported or imported entity, based on the conventions of +the foreign language's compiler in interfacing with the system's linker tool. + +The meaning of link names is implementation defined. If neither a link name nor the Address attribute of +an imported or exported entity is specified, then a link name is chosen in an implementation-defined +manner, based on the external name if one is specified. + +Pragma Linker_Options has the effect of passing its string argument as a parameter to the system linker (if +one exists), if the immediately enclosing compilation unit is included in the partition being linked. The +interpretation of the string argument, and the way in which the string arguments from multiple +Linker_Options pragmas are combined, is implementation defined. + +30/3 + +31/3 + +32/3 + +33/3 + +34 + +35 + +36 + +37 + +Notwithstanding what this International Standard says elsewhere, the elaboration of a declaration with a +True Import aspect does not create the entity. Such an elaboration has no other effect than to allow the +defining name to denote the external entity. + +38/3 + +Dynamic Semantics + +It is the programmer's responsibility to ensure that the use of interfacing aspects does not violate Ada +semantics; otherwise, program execution is erroneous. + +38.1/3 + +Erroneous Execution + +Implementation Advice + +If an implementation supports Export for a given language, then it should also allow the main subprogram +to be written in that language. It should support some mechanism for invoking the elaboration of the Ada +library units included in the system, and for invoking the finalization of the environment task. On typical +systems, the recommended mechanism is to provide two subprograms whose link names are "adainit" and +"adafinal". Adainit should contain the elaboration code for library units. Adafinal should contain the +finalization code. These subprograms should have no effect the second and subsequent time they are +called. + +39/3 + +Automatic elaboration of preelaborated packages should be provided when specifying the Export aspect as +True is supported. + +40/3 + +581 13 December 2012 + +Interfacing Aspects B.1 + + Ada Reference Manual — 2012 Edition + +41/3 + +42/3 + +43/3 + +44/3 + +47 + +48/3 + +49/2 + +For each supported convention L other than Intrinsic, an implementation should support specifying the +Import and Export aspects for objects of L-compatible types and for subprograms, and the Convention +aspect for L-eligible types and for subprograms, presuming the other language has corresponding features. +Specifying the Convention aspect need not be supported for scalar types. + +NOTES +1 Implementations may place restrictions on interfacing aspects; for example, requiring each exported entity to be +declared at the library level. + +2 The Convention aspect in combination with the Import aspect indicates the conventions for accessing external entities. +It is possible that the actual entity is written in assembly language, but reflects the conventions of a particular language. +For example, with Convention => Ada can be used to interface to an assembly language routine that obeys the +Ada compiler's calling conventions. + +3 To obtain “call-back” to an Ada subprogram from a foreign language environment, the Convention aspect should be +specified both for the access-to-subprogram type and the specific subprogram(s) to which 'Access is applied. + +Paragraphs 45 and 46 were deleted. + +4 See also 13.8, “Machine Code Insertions”. + +5 If both External_Name and Link_Name are specified for a given entity, then the External_Name is ignored. + +This paragraph was deleted. + +50 + +Example of interfacing pragmas: + +Examples + +51/3 + +1 + +2 + +3 + +4 + +5 + +package Fortran_Library is + function Sqrt (X : Float) return Float + with Import => True, Convention => Fortran; + type Matrix is array (Natural range <>, Natural range <>) of Float + with Convention => Fortran; + function Invert (M : Matrix) return Matrix + with Import => True, Convention => Fortran; +end Fortran_Library; + +B.2 The Package Interfaces + +Package Interfaces is the parent of several library packages that declare types and other entities useful for +interfacing to foreign languages. It also contains some implementation-defined types that are useful across +more than one language (in particular for interfacing to assembly language). + +The library package Interfaces has the following skeletal declaration: + +Static Semantics + +package Interfaces is + pragma Pure(Interfaces); + type Integer_n is range -2**(n-1) .. 2**(n-1) - 1; --2's complement + type Unsigned_n is mod 2**n; + +B.1 Interfacing Aspects + +13 December 2012 582 + + + Ada Reference Manual — 2012 Edition + + function Shift_Left (Value : Unsigned_n; Amount : Natural) + return Unsigned_n; + function Shift_Right (Value : Unsigned_n; Amount : Natural) + return Unsigned_n; + function Shift_Right_Arithmetic (Value : Unsigned_n; Amount : Natural) + return Unsigned_n; + function Rotate_Left (Value : Unsigned_n; Amount : Natural) + return Unsigned_n; + function Rotate_Right (Value : Unsigned_n; Amount : Natural) + return Unsigned_n; + ... +end Interfaces; + +Implementation Requirements + +An implementation shall provide the following declarations in the visible part of package Interfaces: +• Signed and modular integer types of n bits, if supported by the target architecture, for each n that +is at least the size of a storage element and that is a factor of the word size. The names of these +types are of the form Integer_n for the signed types, and Unsigned_n for the modular types; +• For each such modular type in Interfaces, shifting and rotating subprograms as specified in the +declaration of Interfaces above. These subprograms are Intrinsic. They operate on a bit-by-bit +basis, using the binary representation of the value of the operands to yield a binary +representation for the result. The Amount parameter gives the number of bits by which to shift or +rotate. For shifting, zero bits are shifted in, except in the case of Shift_Right_Arithmetic, where +one bits are shifted in if Value is at least half the modulus. + +• Floating point types corresponding to each floating point format fully supported by the + +hardware. + +Implementation Permissions + +An implementation may provide implementation-defined library units that are children of Interfaces, and +may add declarations to the visible part of Interfaces in addition to the ones defined above. + +A child package of package Interfaces with the name of a convention may be provided independently of +whether the convention is supported by the Convention aspect and vice versa. Such a child package should +contain any declarations that would be useful for interfacing to the language (implementation) represented +by the convention. Any declarations useful for interfacing to any language on the given hardware +architecture should be provided directly in Interfaces. + +This paragraph was deleted. + +Implementation Advice + +An implementation supporting an interface to C, COBOL, or Fortran should provide the corresponding +package or packages described in the following subclauses. + +B.3 Interfacing with C and C++ + +The facilities relevant to interfacing with the C language and the corresponding subset of the C++ +language are the package Interfaces.C and its children, and support for specifying the Convention aspect +with convention_identifiers C and C_Pass_By_Copy. + +The package Interfaces.C contains the basic types, constants, and subprograms that allow an Ada program +to pass scalars and strings to C and C++ functions. When this subclause mentions a C entity, the reference +also applies to the corresponding entity in C++. + +6 + +7 + +8 + +9 + +10 + +11 + +11.1/3 + +12/2 + +13/3 + +1/3 + +2/3 + +583 13 December 2012 + +The Package Interfaces B.2 + + Ada Reference Manual — 2012 Edition + +The library package Interfaces.C has the following declaration: + +Static Semantics + +package Interfaces.C is + pragma Pure(C); + -- Declarations based on C's + CHAR_BIT : constant := implementation-defined; -- typically 8 + SCHAR_MIN : constant := implementation-defined; -- typically –128 + SCHAR_MAX : constant := implementation-defined; -- typically 127 + UCHAR_MAX : constant := implementation-defined; -- typically 255 + -- Signed and Unsigned Integers + type int is range implementation-defined; + type short is range implementation-defined; + type long is range implementation-defined; + type signed_char is range SCHAR_MIN .. SCHAR_MAX; + for signed_char'Size use CHAR_BIT; + type unsigned is mod implementation-defined; + type unsigned_short is mod implementation-defined; + type unsigned_long is mod implementation-defined; + type unsigned_char is mod (UCHAR_MAX+1); + for unsigned_char'Size use CHAR_BIT; + subtype plain_char is implementation-defined; + type ptrdiff_t is range implementation-defined; + type size_t is mod implementation-defined; + -- Floating Point + type C_float is digits implementation-defined; + type double is digits implementation-defined; + type long_double is digits implementation-defined; + -- Characters and Strings + type char is ; + nul : constant char := implementation-defined; + function To_C (Item : in Character) return char; + function To_Ada (Item : in char) return Character; + type char_array is array (size_t range <>) of aliased char + with Pack; + for char_array'Component_Size use CHAR_BIT; + function Is_Nul_Terminated (Item : in char_array) return Boolean; + function To_C (Item : in String; + Append_Nul : in Boolean := True) + return char_array; + function To_Ada (Item : in char_array; + Trim_Nul : in Boolean := True) + return String; + procedure To_C (Item : in String; + Target : out char_array; + Count : out size_t; + Append_Nul : in Boolean := True); + procedure To_Ada (Item : in char_array; + Target : out String; + Count : out Natural; + Trim_Nul : in Boolean := True); + -- Wide Character and Wide String + type wchar_t is ; + +3 + +4 + +5 + +6 + +7 + +8 + +9 + +10 + +11 + +12 + +13 + +14 + +15 + +16 + +17 + +18 + +19 + +20/1 + +21 + +22 + +23/3 + +24 + +25 + +26 + +27 + +28 + +29 + +30/1 + +B.3 Interfacing with C and C++ + +13 December 2012 584 + + Ada Reference Manual — 2012 Edition + + wide_nul : constant wchar_t := implementation-defined; + function To_C (Item : in Wide_Character) return wchar_t; + function To_Ada (Item : in wchar_t ) return Wide_Character; + type wchar_array is array (size_t range <>) of aliased wchar_t + with Pack; +This paragraph was deleted. + function Is_Nul_Terminated (Item : in wchar_array) return Boolean; + function To_C (Item : in Wide_String; + Append_Nul : in Boolean := True) + return wchar_array; + function To_Ada (Item : in wchar_array; + Trim_Nul : in Boolean := True) + return Wide_String; + procedure To_C (Item : in Wide_String; + Target : out wchar_array; + Count : out size_t; + Append_Nul : in Boolean := True); + procedure To_Ada (Item : in wchar_array; + Target : out Wide_String; + Count : out Natural; + Trim_Nul : in Boolean := True); + -- ISO/IEC 10646:2003 compatible types defined by ISO/IEC TR 19769:2004. + type char16_t is ; + char16_nul : constant char16_t := implementation-defined; + function To_C (Item : in Wide_Character) return char16_t; + function To_Ada (Item : in char16_t) return Wide_Character; + type char16_array is array (size_t range <>) of aliased char16_t + with Pack; +This paragraph was deleted. + function Is_Nul_Terminated (Item : in char16_array) return Boolean; + function To_C (Item : in Wide_String; + Append_Nul : in Boolean := True) + return char16_array; + function To_Ada (Item : in char16_array; + Trim_Nul : in Boolean := True) + return Wide_String; + procedure To_C (Item : in Wide_String; + Target : out char16_array; + Count : out size_t; + Append_Nul : in Boolean := True); + procedure To_Ada (Item : in char16_array; + Target : out Wide_String; + Count : out Natural; + Trim_Nul : in Boolean := True); + type char32_t is ; + char32_nul : constant char32_t := implementation-defined; + function To_C (Item : in Wide_Wide_Character) return char32_t; + function To_Ada (Item : in char32_t) return Wide_Wide_Character; + type char32_array is array (size_t range <>) of aliased char32_t + with Pack; +This paragraph was deleted. + function Is_Nul_Terminated (Item : in char32_array) return Boolean; + function To_C (Item : in Wide_Wide_String; + Append_Nul : in Boolean := True) + return char32_array; + +31/1 + +32 + +33/3 + +34/3 + +35 + +36 + +37 + +38 + +39 + +39.1/2 + +39.2/2 + +39.3/2 + +39.4/2 + +39.5/3 + +39.6/3 + +39.7/2 + +39.8/2 + +39.9/2 + +39.10/2 + +39.11/2 + +39.12/2 + +39.13/2 + +39.14/3 + +39.15/3 + +39.16/2 + +585 13 December 2012 + +Interfacing with C and C++ B.3 + + 39.17/2 + +39.18/2 + +39.19/2 + +40 + +41 + +42 + +43/2 + +44 + +45 + +46 + +47 + +48 + +49 + +50/2 + +51 + +Ada Reference Manual — 2012 Edition + + function To_Ada (Item : in char32_array; + Trim_Nul : in Boolean := True) + return Wide_Wide_String; + procedure To_C (Item : in Wide_Wide_String; + Target : out char32_array; + Count : out size_t; + Append_Nul : in Boolean := True); + procedure To_Ada (Item : in char32_array; + Target : out Wide_Wide_String; + Count : out Natural; + Trim_Nul : in Boolean := True); + Terminator_Error : exception; +end Interfaces.C; + +Each of the types declared in Interfaces.C is C-compatible. + +The types int, short, long, unsigned, ptrdiff_t, size_t, double, char, wchar_t, char16_t, and char32_t +correspond respectively to the C types having the same names. The types signed_char, unsigned_short, +unsigned_long, unsigned_char, C_float, and long_double correspond respectively to the C types signed +char, unsigned short, unsigned long, unsigned char, float, and long double. + +The type of the subtype plain_char is either signed_char or unsigned_char, depending on the C +implementation. + +function To_C (Item : in Character) return char; +function To_Ada (Item : in char ) return Character; + +The functions To_C and To_Ada map between the Ada type Character and the C type char. + +function Is_Nul_Terminated (Item : in char_array) return Boolean; + +The result of Is_Nul_Terminated is True if Item contains nul, and is False otherwise. + +function To_C (Item : in String; Append_Nul : in Boolean := True) + return char_array; + +function To_Ada (Item : in char_array; Trim_Nul : in Boolean := True) + return String; + +The result of To_C is a char_array value of length Item'Length (if Append_Nul is False) or +Item'Length+1 (if Append_Nul is True). The lower bound is 0. For each component Item(I), the +corresponding component in the result is To_C applied to Item(I). The value nul is appended if +Append_Nul is True. If Append_Nul is False and Item'Length is 0, then To_C propagates +Constraint_Error. + +The result of To_Ada is a String whose length is Item'Length (if Trim_Nul is False) or the length +of the slice of Item preceding the first nul (if Trim_Nul is True). The lower bound of the result is +1. If Trim_Nul is False, then for each component Item(I) the corresponding component in the +result is To_Ada applied to Item(I). If Trim_Nul is True, then for each component Item(I) before +the first nul the corresponding component in the result is To_Ada applied to Item(I). The +function propagates Terminator_Error if Trim_Nul is True and Item does not contain nul. + +B.3 Interfacing with C and C++ + +13 December 2012 586 + + + Ada Reference Manual — 2012 Edition + +procedure To_C (Item : in String; + Target : out char_array; + Count : out size_t; + Append_Nul : in Boolean := True); + +procedure To_Ada (Item : in char_array; + Target : out String; + Count : out Natural; + Trim_Nul : in Boolean := True); + +For procedure To_C, each element of Item is converted (via the To_C function) to a char, which +is assigned to the corresponding element of Target. If Append_Nul is True, nul is then assigned +to the next element of Target. In either case, Count is set to the number of Target elements +assigned. If Target is not long enough, Constraint_Error is propagated. + +For procedure To_Ada, each element of Item (if Trim_Nul is False) or each element of Item +preceding the first nul (if Trim_Nul is True) is converted (via the To_Ada function) to a +Character, which is assigned to the corresponding element of Target. Count is set to the number +of Target elements assigned. If Target is not long enough, Constraint_Error is propagated. If +Trim_Nul is True and Item does not contain nul, then Terminator_Error is propagated. + +function Is_Nul_Terminated (Item : in wchar_array) return Boolean; + +The result of Is_Nul_Terminated is True if Item contains wide_nul, and is False otherwise. + +function To_C (Item : in Wide_Character) return wchar_t; +function To_Ada (Item : in wchar_t ) return Wide_Character; + +To_C and To_Ada provide the mappings between the Ada and C wide character types. + +function To_C (Item : in Wide_String; + Append_Nul : in Boolean := True) + return wchar_array; + +function To_Ada (Item : in wchar_array; + Trim_Nul : in Boolean := True) + return Wide_String; + +procedure To_C (Item : in Wide_String; + Target : out wchar_array; + Count : out size_t; + Append_Nul : in Boolean := True); + +procedure To_Ada (Item : in wchar_array; + Target : out Wide_String; + Count : out Natural; + Trim_Nul : in Boolean := True); + +52 + +53 + +54 + +55 + +56 + +57 + +58 + +59 + +The To_C and To_Ada subprograms that convert between Wide_String and wchar_array have +analogous effects to the To_C and To_Ada subprograms that convert between String and +char_array, except that wide_nul is used instead of nul. + +60 + +function Is_Nul_Terminated (Item : in char16_array) return Boolean; + +The result of Is_Nul_Terminated is True if Item contains char16_nul, and is False otherwise. + +function To_C (Item : in Wide_Character) return char16_t; +function To_Ada (Item : in char16_t ) return Wide_Character; + +To_C and To_Ada provide mappings between the Ada and C 16-bit character types. + +60.1/2 + +60.2/2 + +60.3/2 + +60.4/2 + +587 13 December 2012 + +Interfacing with C and C++ B.3 + + + + + + Ada Reference Manual — 2012 Edition + +60.5/2 + +function To_C (Item : in Wide_String; + Append_Nul : in Boolean := True) + return char16_array; + +function To_Ada (Item : in char16_array; + Trim_Nul : in Boolean := True) + return Wide_String; + +procedure To_C (Item : in Wide_String; + Target : out char16_array; + Count : out size_t; + Append_Nul : in Boolean := True); + +procedure To_Ada (Item : in char16_array; + Target : out Wide_String; + Count : out Natural; + Trim_Nul : in Boolean := True); + +60.6/2 + +60.7/2 + +60.8/2 + +60.9/2 + +60.10/2 + +60.11/2 + +The To_C and To_Ada subprograms that convert between Wide_String and char16_array have +analogous effects to the To_C and To_Ada subprograms that convert between String and +char_array, except that char16_nul is used instead of nul. + +function Is_Nul_Terminated (Item : in char32_array) return Boolean; + +The result of Is_Nul_Terminated is True if Item contains char16_nul, and is False otherwise. + +function To_C (Item : in Wide_Wide_Character) return char32_t; +function To_Ada (Item : in char32_t ) return Wide_Wide_Character; + +To_C and To_Ada provide mappings between the Ada and C 32-bit character types. + +function To_C (Item : in Wide_Wide_String; + Append_Nul : in Boolean := True) + return char32_array; + +function To_Ada (Item : in char32_array; + Trim_Nul : in Boolean := True) + return Wide_Wide_String; + +procedure To_C (Item : in Wide_Wide_String; + Target : out char32_array; + Count : out size_t; + Append_Nul : in Boolean := True); + +procedure To_Ada (Item : in char32_array; + Target : out Wide_Wide_String; + Count : out Natural; + Trim_Nul : in Boolean := True); + +60.12/2 + +The To_C and To_Ada subprograms that convert between Wide_Wide_String and char32_array +have analogous effects to the To_C and To_Ada subprograms that convert between String and +char_array, except that char32_nul is used instead of nul. + +60.13/3 + +The Convention aspect with convention_identifier C_Pass_By_Copy shall only be specified for a type. + +60.14/2 + +The eligibility rules in B.1 do not apply to convention C_Pass_By_Copy. Instead, a type T is eligible for +convention C_Pass_By_Copy if T is an unchecked union type or if T is a record type that has no +discriminants and that only has components with statically constrained subtypes, and each component is +C-compatible. + +60.15/3 + +If a type is C_Pass_By_Copy-compatible, then it is also C-compatible. + +B.3 Interfacing with C and C++ + +13 December 2012 588 + + + + + + + + Ada Reference Manual — 2012 Edition + +An implementation shall support specifying aspect Convention with a C convention_identifier for a C- +eligible type (see B.1). An implementation shall support specifying aspect Convention with a +C_Pass_By_Copy convention_identifier for a C_Pass_By_Copy-eligible type. + +61/3 + +Implementation Requirements + +An implementation may provide additional declarations in the C interface packages. + +Implementation Permissions + +An implementation need not support specifying the Convention aspect with convention_identifier C in the +following cases: + +• for a subprogram that has a parameter of an unconstrained array subtype, unless the Import + +aspect has the value True for the subprogram; + +• for a function with an unconstrained array result subtype; +• for an object whose nominal subtype is an unconstrained array subtype. + +Implementation Advice + +The constants nul, wide_nul, char16_nul, and char32_nul should have a representation of zero. + +An implementation should support the following interface correspondences between Ada and C. + +• An Ada procedure corresponds to a void-returning C function. +• An Ada function corresponds to a non-void C function. +• An Ada in scalar parameter is passed as a scalar argument to a C function. +• An Ada in parameter of an access-to-object type with designated type T is passed as a t* + +argument to a C function, where t is the C type corresponding to the Ada type T. + +• An Ada access T parameter, or an Ada out or in out parameter of an elementary type T, is +passed as a t* argument to a C function, where t is the C type corresponding to the Ada type T. +In the case of an elementary out or in out parameter, a pointer to a temporary copy is used to +preserve by-copy semantics. + +62 + +62.1/3 + +62.2/3 + +62.3/3 + +62.4/3 + +62.5/3 + +63 + +64 + +65 + +66 + +67 + +68 + +• An Ada parameter of a (record) type T of convention C_Pass_By_Copy, of mode in, is passed as + +68.1/2 + +a t argument to a C function, where t is the C struct corresponding to the Ada type T. + +• An Ada parameter of a record type T, of any mode, other than an in parameter of a type of +convention C_Pass_By_Copy, is passed as a t* argument to a C function, where t is the C struct +corresponding to the Ada type T. + +• An Ada parameter of an array type with component type T, of any mode, is passed as a t* + +argument to a C function, where t is the C type corresponding to the Ada type T. + +• An Ada parameter of an access-to-subprogram type is passed as a pointer to a C function whose + +prototype corresponds to the designated subprogram's specification. + +• An Ada parameter of a private type is passed as specified for the full view of the type. +• The rules of correspondence given above for parameters of mode in also apply to the return + +object of a function. + +This paragraph was deleted. + +NOTES +6 Values of type char_array are not implicitly terminated with nul. If a char_array is to be passed as a parameter to an +imported C function requiring nul termination, it is the programmer's responsibility to obtain this effect. + +69/2 + +70 + +71 + +71.1/3 + +71.2/3 + +71.3/3 + +72 + +589 13 December 2012 + +Interfacing with C and C++ B.3 + + Ada Reference Manual — 2012 Edition + +7 To obtain the effect of C's sizeof(item_type), where Item_Type is the corresponding Ada type, evaluate the expression: +size_t(Item_Type'Size/CHAR_BIT). + +This paragraph was deleted. + +8 A C function that takes a variable number of arguments can correspond to several Ada subprograms, taking various +specific numbers and types of parameters. + +Examples + +Example of using the Interfaces.C package: +--Calling the C Library Function strcpy +with Interfaces.C; +procedure Test is + package C renames Interfaces.C; + use type C.char_array; + -- Call strcpy: + -- C definition of strcpy: char *strcpy(char *s1, const char *s2); + -- This function copies the string pointed to by s2 (including the terminating null character) + -- into the array pointed to by s1. If copying takes place between objects that overlap, + -- the behavior is undefined. The strcpy function returns the value of s1. + -- Note: since the C function's return value is of no interest, the Ada interface is a procedure + procedure Strcpy (Target : out C.char_array; + Source : in C.char_array) + with Import => True, Convention => C, External_Name => "strcpy"; +This paragraph was deleted. + + Chars1 : C.char_array(1..20); + Chars2 : C.char_array(1..20); +begin + Chars2(1..6) := "qwert" & C.nul; + + Strcpy(Chars1, Chars2); +-- Now Chars1(1..6) = "qwert" & C.Nul +end Test; + +73 + +74/2 + +75 + +76 + +77 + +78/3 + +79/3 + +80 + +81 + +82 + +83 + +84 + +B.3 Interfacing with C and C++ + +13 December 2012 590 + + Ada Reference Manual — 2012 Edition + +B.3.1 The Package Interfaces.C.Strings + +The package Interfaces.C.Strings declares types and subprograms allowing an Ada program to allocate, +reference, update, and free C-style strings. In particular, the private type chars_ptr corresponds to a +common use of “char *” in C programs, and an object of this type can be passed to a subprogram to which +with Import => True, Convention => C has been specified, and for which “char *” is the +type of the argument of the C function. + +The library package Interfaces.C.Strings has the following declaration: + +Static Semantics + +package Interfaces.C.Strings is + pragma Preelaborate(Strings); + type char_array_access is access all char_array; + type chars_ptr is private; + pragma Preelaborable_Initialization(chars_ptr); + type chars_ptr_array is array (size_t range <>) of aliased chars_ptr; + Null_Ptr : constant chars_ptr; + function To_Chars_Ptr (Item : in char_array_access; + Nul_Check : in Boolean := False) + return chars_ptr; + function New_Char_Array (Chars : in char_array) return chars_ptr; + function New_String (Str : in String) return chars_ptr; + procedure Free (Item : in out chars_ptr); + Dereference_Error : exception; + function Value (Item : in chars_ptr) return char_array; + function Value (Item : in chars_ptr; Length : in size_t) + return char_array; + function Value (Item : in chars_ptr) return String; + function Value (Item : in chars_ptr; Length : in size_t) + return String; + function Strlen (Item : in chars_ptr) return size_t; + procedure Update (Item : in chars_ptr; + Offset : in size_t; + Chars : in char_array; + Check : in Boolean := True); + procedure Update (Item : in chars_ptr; + Offset : in size_t; + Str : in String; + Check : in Boolean := True); + Update_Error : exception; +private + ... -- not specified by the language +end Interfaces.C.Strings; + +The type chars_ptr is C-compatible and corresponds to the use of C's “char *” for a pointer to the first char +in a char array terminated by nul. When an object of type chars_ptr is declared, its value is by default set +to Null_Ptr, unless the object is imported (see B.1). + +1/3 + +2 + +3 + +4 + +5/2 + +6/2 + +7 + +8 + +9 + +10 + +11 + +12 + +13 + +14 + +15 + +16 + +17 + +18 + +19 + +20 + +21 + +22 + +591 13 December 2012 + +The Package Interfaces.C.Strings B.3.1 + + Ada Reference Manual — 2012 Edition + +function To_Chars_Ptr (Item : in char_array_access; + Nul_Check : in Boolean := False) + return chars_ptr; + +If Item is null, then To_Chars_Ptr returns Null_Ptr. If Item is not null, Nul_Check is True, and +Item.all does not contain nul, then the function propagates Terminator_Error; otherwise, +To_Chars_Ptr performs a pointer conversion with no allocation of memory. + +function New_Char_Array (Chars : in char_array) return chars_ptr; + +This function returns a pointer to an allocated object initialized to Chars(Chars'First .. Index) & +nul, where + +• Index = Chars'Last if Chars does not contain nul, or +• Index is the smallest size_t value I such that Chars(I+1) = nul. + +Storage_Error is propagated if the allocation fails. + +function New_String (Str : in String) return chars_ptr; + +This function is equivalent to New_Char_Array(To_C(Str)). + +procedure Free (Item : in out chars_ptr); + +If Item is Null_Ptr, then Free has no effect. Otherwise, Free releases the storage occupied by +Value(Item), and resets Item to Null_Ptr. + +function Value (Item : in chars_ptr) return char_array; + +If Item = Null_Ptr, then Value propagates Dereference_Error. Otherwise, Value returns the +prefix of the array of chars pointed to by Item, up to and including the first nul. The lower bound +of the result is 0. If Item does not point to a nul-terminated string, then execution of Value is +erroneous. + +function Value (Item : in chars_ptr; Length : in size_t) + return char_array; + +If Item = Null_Ptr, then Value propagates Dereference_Error. Otherwise, Value returns the +shorter of two arrays, either the first Length chars pointed to by Item, or Value(Item). The lower +bound of the result is 0. If Length is 0, then Value propagates Constraint_Error. + +function Value (Item : in chars_ptr) return String; + +Equivalent to To_Ada(Value(Item), Trim_Nul=>True). + +function Value (Item : in chars_ptr; Length : in size_t) + return String; + +Equivalent to To_Ada(Value(Item, Length) & nul, Trim_Nul=>True). + +function Strlen (Item : in chars_ptr) return size_t; + +Returns Val'Length–1 where Val = Value(Item); propagates Dereference_Error if Item = +Null_Ptr. + +procedure Update (Item : in chars_ptr; + Offset : in size_t; + Chars : in char_array; + Check : Boolean := True); + +If Item = Null_Ptr, then Update propagates Dereference_Error. Otherwise, this procedure +updates the value pointed to by Item, starting at position Offset, using Chars as the data to be + +23 + +24/3 + +25 + +26 + +27 + +28 + +28.1 + +29 + +30 + +31 + +32 + +33 + +34/3 + +35 + +36/3 + +37 + +38 + +39 + +40/1 + +41 + +42 + +43 + +44/1 + +B.3.1 The Package Interfaces.C.Strings + +13 December 2012 592 + + Ada Reference Manual — 2012 Edition + +copied into the array. Overwriting the nul terminator, and skipping with the Offset past the nul +terminator, are both prevented if Check is True, as follows: + +• Let N = Strlen(Item). If Check is True, then: + +• If Offset+Chars'Length>N, propagate Update_Error. + +• Otherwise, overwrite the data in the array pointed to by Item, starting at the char + +at position Offset, with the data in Chars. + +• If Check + +is False, + +then processing + +is as above, but with no check + +that + +Offset+Chars'Length>N. + +procedure Update (Item : in chars_ptr; + Offset : in size_t; + Str : in String; + Check : in Boolean := True); + +45 + +46 + +47 + +48 + +49 + +Equivalent to Update(Item, Offset, To_C(Str, Append_Nul => False), Check). + +50/2 + +51 + +52 + +53 + +54 + +55 + +56 + +57 + +58 + +59 + +60 + +Execution of any of the following is erroneous if the Item parameter is not null_ptr and Item does not point +to a nul-terminated array of chars. + +Erroneous Execution + +• a Value function not taking a Length parameter, +• +• + +the Strlen function. + +the Free procedure, + +Execution of Free(X) is also erroneous if the chars_ptr X was not returned by New_Char_Array or +New_String. + +Reading or updating a freed char_array is erroneous. + +Execution of Update is erroneous if Check is False and a call with Check equal to True would have +propagated Update_Error. + +NOTES +9 New_Char_Array and New_String might be implemented either through the allocation function from the C +environment (“malloc”) or through Ada dynamic memory allocation (“new”). The key points are + +• +• + +the returned value (a chars_ptr) is represented as a C “char *” so that it may be passed to C functions; + +the allocated object should be freed by the programmer via a call of Free, not by a called C function. + +593 13 December 2012 + +The Package Interfaces.C.Strings B.3.1 + + Ada Reference Manual — 2012 Edition + +B.3.2 The Generic Package Interfaces.C.Pointers + +The generic package Interfaces.C.Pointers allows the Ada programmer to perform C-style operations on +pointers. It includes an access type Pointer, Value functions that dereference a Pointer and deliver the +designated array, several pointer arithmetic operations, and “copy” procedures that copy the contents of a +source pointer into the array designated by a destination pointer. As in C, it treats an object Ptr of type +Pointer as a pointer to the first element of an array, so that for example, adding 1 to Ptr yields a pointer to +the second element of the array. + +The generic allows two styles of usage: one in which the array is terminated by a special terminator +element; and another in which the programmer needs to keep track of the length. + +The generic library package Interfaces.C.Pointers has the following declaration: + +Static Semantics + +generic + type Index is (<>); + type Element is private; + type Element_Array is array (Index range <>) of aliased Element; + Default_Terminator : Element; +package Interfaces.C.Pointers is + pragma Preelaborate(Pointers); + type Pointer is access all Element; + function Value(Ref : in Pointer; + Terminator : in Element := Default_Terminator) + return Element_Array; + function Value(Ref : in Pointer; + Length : in ptrdiff_t) + return Element_Array; + Pointer_Error : exception; + -- C-style Pointer arithmetic + function "+" (Left : in Pointer; Right : in ptrdiff_t) return Pointer + with Convention => Intrinsic; + function "+" (Left : in ptrdiff_t; Right : in Pointer) return Pointer + with Convention => Intrinsic; + function "-" (Left : in Pointer; Right : in ptrdiff_t) return Pointer + with Convention => Intrinsic; + function "-" (Left : in Pointer; Right : in Pointer) return ptrdiff_t + with Convention => Intrinsic; + procedure Increment (Ref : in out Pointer) + with Convention => Intrinsic; + procedure Decrement (Ref : in out Pointer) + with Convention => Intrinsic; +This paragraph was deleted. + function Virtual_Length (Ref : in Pointer; + Terminator : in Element := Default_Terminator) + return ptrdiff_t; + procedure Copy_Terminated_Array + (Source : in Pointer; + Target : in Pointer; + Limit : in ptrdiff_t := ptrdiff_t'Last; + Terminator : in Element := Default_Terminator); + procedure Copy_Array (Source : in Pointer; + Target : in Pointer; + Length : in ptrdiff_t); +end Interfaces.C.Pointers; + +1 + +2 + +3 + +4 + +5 + +6 + +7 + +8 + +9 + +10/3 + +11/3 + +12/3 + +13 + +14 + +15 + +16 + +B.3.2 The Generic Package Interfaces.C.Pointers + +13 December 2012 594 + + Ada Reference Manual — 2012 Edition + +The type Pointer is C-compatible and corresponds to one use of C's “Element *”. An object of type Pointer +is interpreted as a pointer to the initial Element in an Element_Array. Two styles are supported: +• Explicit termination of an array value with Default_Terminator (a special terminator value); +• Programmer-managed length, with Default_Terminator treated simply as a data element. + +function Value(Ref : in Pointer; + Terminator : in Element := Default_Terminator) + return Element_Array; + +This function returns an Element_Array whose value is the array pointed to by Ref, up to and +including +Index'First. +Interfaces.C.Strings.Dereference_Error is propagated if Ref is null. + +lower bound of + +first Terminator; + +the array + +the + +the + +is + +function Value(Ref : in Pointer; + Length : in ptrdiff_t) + return Element_Array; + +This function returns an Element_Array comprising the first Length elements pointed to by Ref. +The exception Interfaces.C.Strings.Dereference_Error is propagated if Ref is null. + +The "+" and "–" functions perform arithmetic on Pointer values, based on the Size of the array elements. In +each of these functions, Pointer_Error is propagated if a Pointer parameter is null. + +procedure Increment (Ref : in out Pointer); + +Equivalent to Ref := Ref+1. + +procedure Decrement (Ref : in out Pointer); + +Equivalent to Ref := Ref–1. + +function Virtual_Length (Ref : in Pointer; + Terminator : in Element := Default_Terminator) + return ptrdiff_t; + +Returns the number of Elements, up to the one just before the first Terminator, in Value(Ref, +Terminator). + +procedure Copy_Terminated_Array + (Source : in Pointer; + Target : in Pointer; + Limit : in ptrdiff_t := ptrdiff_t'Last; + Terminator : in Element := Default_Terminator); + +This procedure copies Value(Source, Terminator) into the array pointed to by Target; it stops +either after Terminator has been copied, or the number of elements copied is Limit, whichever +occurs first. Dereference_Error is propagated if either Source or Target is null. + +procedure Copy_Array (Source : in Pointer; + Target : in Pointer; + Length : in ptrdiff_t); + +This procedure copies the first Length elements from the array pointed to by Source, into the +array pointed to by Target. Dereference_Error is propagated if either Source or Target is null. + +It is erroneous to dereference a Pointer that does not designate an aliased Element. + +Erroneous Execution + +Execution of Value(Ref, Terminator) is erroneous if Ref does not designate an aliased Element in an +Element_Array terminated by Terminator. + +595 13 December 2012 + +The Generic Package Interfaces.C.Pointers B.3.2 + +17 + +18 + +19 + +20 + +21 + +22 + +23 + +24 + +25 + +26 + +27 + +28 + +29 + +30 + +31 + +32 + +33 + +34 + +35 + +36 + + 37 + +38 + +39 + +40 + +41 + +42 + +43 + +44 + +45 + +46 + +47 + +48 + +49/1 + +Ada Reference Manual — 2012 Edition + +Execution of Value(Ref, Length) is erroneous if Ref does not designate an aliased Element in an +Element_Array containing at least Length Elements between the designated Element and the end of the +array, inclusive. + +Execution of Virtual_Length(Ref, Terminator) is erroneous if Ref does not designate an aliased Element in +an Element_Array terminated by Terminator. + +Execution of Copy_Terminated_Array(Source, Target, Limit, Terminator) is erroneous in either of the +following situations: + +• Execution of both Value(Source, Terminator) and Value(Source, Limit) are erroneous, or +• Copying writes past the end of the array containing the Element designated by Target. + +Execution of Copy_Array(Source, Target, Length) is erroneous if either Value(Source, Length) is +erroneous, or copying writes past the end of the array containing the Element designated by Target. + +NOTES +10 To compose a Pointer from an Element_Array, use 'Access on the first element. For example (assuming appropriate +instantiations): + +Some_Array : Element_Array(0..5) ; +Some_Pointer : Pointer := Some_Array(0)'Access; + +Example of Interfaces.C.Pointers: + +Examples + +with Interfaces.C.Pointers; +with Interfaces.C.Strings; +procedure Test_Pointers is + package C renames Interfaces.C; + package Char_Ptrs is + new C.Pointers (Index => C.size_t, + Element => C.char, + Element_Array => C.char_array, + Default_Terminator => C.nul); + use type Char_Ptrs.Pointer; + subtype Char_Star is Char_Ptrs.Pointer; + procedure Strcpy (Target_Ptr, Source_Ptr : Char_Star) is + Target_Temp_Ptr : Char_Star := Target_Ptr; + Source_Temp_Ptr : Char_Star := Source_Ptr; + Element : C.char; + begin + if Target_Temp_Ptr = null or Source_Temp_Ptr = null then + raise C.Strings.Dereference_Error; + end if; + loop + Element := Source_Temp_Ptr.all; + Target_Temp_Ptr.all := Element; + exit when C."="(Element, C.nul); + Char_Ptrs.Increment(Target_Temp_Ptr); + Char_Ptrs.Increment(Source_Temp_Ptr); + end loop; + end Strcpy; +begin + ... +end Test_Pointers; + +B.3.2 The Generic Package Interfaces.C.Pointers + +13 December 2012 596 + + Ada Reference Manual — 2012 Edition + +B.3.3 Unchecked Union Types + +Specifying aspect Unchecked_Union to have the value True defines an interface correspondence between +a given discriminated type and some C union. The aspect requires that the associated type shall be given a +representation that allocates no space for its discriminant(s). + +1/3 + +Paragraphs 2 through 3 were moved to Annex J, “Obsolescent Features”. + +For a discriminated record type having a variant_part, the following language-defined representation +aspect may be specified: + +Static Semantics + +Unchecked_Union +The +the +aspect_definition shall be a static expression. If not specified (including by inheritance), +the aspect is False. + +type of aspect Unchecked_Union + +If directly specified, + +is Boolean. + +Paragraphs 4 and 5 were deleted. + +Legality Rules + +A type for which aspect Unchecked_Union is True is called an unchecked union type. A subtype of an +unchecked union type is defined to be an unchecked union subtype. An object of an unchecked union type +is defined to be an unchecked union object. + +All component subtypes of an unchecked union type shall be C-compatible. + +If a component subtype of an unchecked union type is subject to a per-object constraint, then the +component subtype shall be an unchecked union subtype. + +Any name that denotes a discriminant of an object of an unchecked union type shall occur within the +declarative region of the type, and shall not occur within a record_representation_clause. + +The type of a component declared in a variant_part of an unchecked union type shall not need finalization. +In addition to the places where Legality Rules normally apply (see 12.3), this rule also applies in the +private part of an instance of a generic unit. For an unchecked union type declared within the body of a +generic unit, or within the body of any of its descendant library units, no part of the type of a component +declared in a variant_part of the unchecked union type shall be of a formal private type or formal private +extension declared within the formal part of the generic unit. + +The completion of an incomplete or private type declaration having a known_discriminant_part shall not +be an unchecked union type. + +An unchecked union subtype shall only be passed as a generic actual parameter if the corresponding +formal type has no known discriminants or is an unchecked union type. + +An unchecked union type is eligible for convention C. + +All objects of an unchecked union type have the same size. + +Static Semantics + +Discriminants of objects of an unchecked union type are of size zero. + +597 13 December 2012 + +Unchecked Union Types B.3.3 + +3.1/3 + +3.2/3 + +6/3 + +7/2 + +8/2 + +9/3 + +10/3 + +11/2 + +12/2 + +13/2 + +14/2 + +15/2 + + + Ada Reference Manual — 2012 Edition + +16/2 + +17/2 + +18/2 + +Any check which would require reading a discriminant of an unchecked union object is suppressed (see +11.5). These checks include: + +• The check performed when addressing a variant component (i.e., a component that was declared +in a variant part) of an unchecked union object that the object has this component (see 4.1.3). +• Any checks associated with a type or subtype conversion of a value of an unchecked union type +(see 4.6). This includes, for example, the check associated with the implicit subtype conversion +of an assignment statement. + +19/2 + +• The subtype membership check associated with the evaluation of a qualified expression (see 4.7) + +or an uninitialized allocator (see 4.8). + +Dynamic Semantics + +20/2 + +21/2 + +22/2 + +23/2 + +A view of an unchecked union object (including a type conversion or function call) has inferable +discriminants if it has a constrained nominal subtype, unless the object is a component of an enclosing +unchecked union object that is subject to a per-object constraint and the enclosing object lacks inferable +discriminants. + +An expression of an unchecked union type has inferable discriminants if it is either a name of an object +with inferable discriminants or a qualified expression whose subtype_mark denotes a constrained subtype. + +Program_Error is raised in the following cases: + +• Evaluation of the predefined equality operator for an unchecked union type if either of the + +operands lacks inferable discriminants. + +24/2 + +• Evaluation of the predefined equality operator for a type which has a subcomponent of an + +unchecked union type whose nominal subtype is unconstrained. + +25/2 + +• Evaluation of a membership test if the subtype_mark denotes a constrained unchecked union + +subtype and the expression lacks inferable discriminants. + +26/2 + +• Conversion from a derived unchecked union type to an unconstrained non-unchecked-union type + +if the operand of the conversion lacks inferable discriminants. + +27/2 + +• Execution of the default implementation of the Write or Read attribute of an unchecked union + +type. + +28/2 + +• Execution of the default implementation of the Output or Input attribute of an unchecked union + +type if the type lacks default discriminant values. + +Paragraph 29 was deleted. + +30/2 + +31/3 + +32/2 + +NOTES +11 The use of an unchecked union to obtain the effect of an unchecked conversion results in erroneous execution (see +11.5). Execution of the following example is erroneous even if Float'Size = Integer'Size: + +type T (Flag : Boolean := False) is + record + case Flag is + when False => + F1 : Float := 0.0; + when True => + F2 : Integer := 0; + end case; + end record + with Unchecked_Union; +X : T; +Y : Integer := X.F2; -- erroneous + +B.3.3 Unchecked Union Types + +13 December 2012 598 + + Ada Reference Manual — 2012 Edition + +B.4 Interfacing with COBOL + +The facilities relevant to interfacing with the COBOL language are the package Interfaces.COBOL and +support for specifying the Convention aspect with convention_identifier COBOL. + +1/3 + +The COBOL interface package supplies several sets of facilities: + +• A set of types corresponding to the native COBOL types of the supported COBOL +implementation (so-called “internal COBOL representations”), allowing Ada data to be passed +as parameters to COBOL programs + +• A set of types and constants reflecting external data representations such as might be found in +files or databases, allowing COBOL-generated data to be read by an Ada program, and Ada- +generated data to be read by COBOL programs + +• A generic package for converting between an Ada decimal type value and either an internal or + +external COBOL representation + +The library package Interfaces.COBOL has the following declaration: + +Static Semantics + +package Interfaces.COBOL is + pragma Preelaborate(COBOL); +-- Types and operations for internal data representations + type Floating is digits implementation-defined; + type Long_Floating is digits implementation-defined; + type Binary is range implementation-defined; + type Long_Binary is range implementation-defined; + Max_Digits_Binary : constant := implementation-defined; + Max_Digits_Long_Binary : constant := implementation-defined; + type Decimal_Element is mod implementation-defined; + type Packed_Decimal is array (Positive range <>) of Decimal_Element + with Pack; + type COBOL_Character is implementation-defined character type; + Ada_To_COBOL : array (Character) of COBOL_Character := implementation-defined; + COBOL_To_Ada : array (COBOL_Character) of Character := implementation-defined; + type Alphanumeric is array (Positive range <>) of COBOL_Character + with Pack; + function To_COBOL (Item : in String) return Alphanumeric; + function To_Ada (Item : in Alphanumeric) return String; + procedure To_COBOL (Item : in String; + Target : out Alphanumeric; + Last : out Natural); + procedure To_Ada (Item : in Alphanumeric; + Target : out String; + Last : out Natural); + type Numeric is array (Positive range <>) of COBOL_Character + with Pack; +-- Formats for COBOL data representations + type Display_Format is private; + Unsigned : constant Display_Format; + Leading_Separate : constant Display_Format; + Trailing_Separate : constant Display_Format; + Leading_Nonseparate : constant Display_Format; + Trailing_Nonseparate : constant Display_Format; + +2 + +3 + +4 + +5 + +6 + +7 + +8 + +9 + +10 + +11 + +12/3 + +13 + +14 + +15 + +16/3 + +17 + +18 + +19 + +20/3 + +21 + +22 + +23 + +599 13 December 2012 + +Interfacing with COBOL B.4 + + Ada Reference Manual — 2012 Edition + +24 + +25 + +26 + +27 + +28 + +29/3 + +30 + +31 + +32 + +33 + +34 + +35 + +36 + +37 + +38 + +39 + +40 + +41 + +42 + +43 + +44 + +45 + +46 + +47 + +48 + +49 + +50 + +51 + +52 + + type Binary_Format is private; + High_Order_First : constant Binary_Format; + Low_Order_First : constant Binary_Format; + Native_Binary : constant Binary_Format; + type Packed_Format is private; + Packed_Unsigned : constant Packed_Format; + Packed_Signed : constant Packed_Format; +-- Types for external representation of COBOL binary data + type Byte is mod 2**COBOL_Character'Size; + type Byte_Array is array (Positive range <>) of Byte + with Pack; + Conversion_Error : exception; + generic + type Num is delta <> digits <>; + package Decimal_Conversions is + -- Display Formats: data values are represented as Numeric + function Valid (Item : in Numeric; + Format : in Display_Format) return Boolean; + function Length (Format : in Display_Format) return Natural; + function To_Decimal (Item : in Numeric; + Format : in Display_Format) return Num; + function To_Display (Item : in Num; + Format : in Display_Format) return Numeric; + -- Packed Formats: data values are represented as Packed_Decimal + function Valid (Item : in Packed_Decimal; + Format : in Packed_Format) return Boolean; + function Length (Format : in Packed_Format) return Natural; + function To_Decimal (Item : in Packed_Decimal; + Format : in Packed_Format) return Num; + function To_Packed (Item : in Num; + Format : in Packed_Format) return Packed_Decimal; + -- Binary Formats: external data values are represented as Byte_Array + function Valid (Item : in Byte_Array; + Format : in Binary_Format) return Boolean; + function Length (Format : in Binary_Format) return Natural; + function To_Decimal (Item : in Byte_Array; + Format : in Binary_Format) return Num; + function To_Binary (Item : in Num; + Format : in Binary_Format) return Byte_Array; + -- Internal Binary formats: data values are of type Binary or Long_Binary + function To_Decimal (Item : in Binary) return Num; + function To_Decimal (Item : in Long_Binary) return Num; + function To_Binary (Item : in Num) return Binary; + function To_Long_Binary (Item : in Num) return Long_Binary; + end Decimal_Conversions; +private + ... -- not specified by the language +end Interfaces.COBOL; + +Each of the types in Interfaces.COBOL is COBOL-compatible. + +The types Floating and Long_Floating correspond to the native types in COBOL for data items with +computational usage implemented by floating point. The types Binary and Long_Binary correspond to the + +B.4 Interfacing with COBOL + +13 December 2012 600 + + Ada Reference Manual — 2012 Edition + +native types in COBOL for data items with binary usage, or with computational usage implemented by +binary. + +Max_Digits_Binary is the largest number of decimal digits in a numeric value that is represented as +Binary. Max_Digits_Long_Binary is the largest number of decimal digits in a numeric value that is +represented as Long_Binary. + +The type Packed_Decimal corresponds to COBOL's packed-decimal usage. + +The type COBOL_Character defines the run-time character set used in the COBOL implementation. +Ada_To_COBOL and COBOL_To_Ada are the mappings between the Ada and COBOL run-time +character sets. + +Type Alphanumeric corresponds to COBOL's alphanumeric data category. + +Each of the functions To_COBOL and To_Ada converts its parameter based on the mappings +Ada_To_COBOL and COBOL_To_Ada, respectively. The length of the result for each is the length of the +parameter, and the lower bound of the result is 1. Each component of the result is obtained by applying the +relevant mapping to the corresponding component of the parameter. + +Each of the procedures To_COBOL and To_Ada copies converted elements from Item to Target, using the +appropriate mapping (Ada_To_COBOL or COBOL_To_Ada, respectively). The index in Target of the last +element assigned is returned in Last (0 if Item is a null array). If Item'Length exceeds Target'Length, +Constraint_Error is propagated. + +Type Numeric corresponds to COBOL's numeric data category with display usage. + +The types Display_Format, Binary_Format, and Packed_Format are used in conversions between Ada +decimal type values and COBOL internal or external data representations. The value of the constant +Native_Binary is either High_Order_First or Low_Order_First, depending on the implementation. + +function Valid (Item : in Numeric; + Format : in Display_Format) return Boolean; + +The function Valid checks that the Item parameter has a value consistent with the value of +Format. If the value of Format is other than Unsigned, Leading_Separate, and Trailing_Separate, +the effect is implementation defined. If Format does have one of these values, the following +rules apply: + +• Format=Unsigned: if Item comprises one or more decimal digit characters, then Valid + +returns True, else it returns False. + +• Format=Leading_Separate: if Item comprises a single occurrence of the plus or minus +sign character, and then one or more decimal digit characters, then Valid returns True, +else it returns False. + +• Format=Trailing_Separate: if Item comprises one or more decimal digit characters and +finally a plus or minus sign character, then Valid returns True, else it returns False. + +function Length (Format : in Display_Format) return Natural; + +The Length function returns the minimal length of a Numeric value sufficient to hold any value +of type Num when represented as Format. + +53 + +54 + +55 + +56 + +57 + +58 + +59 + +60 + +61 + +62 + +63/3 + +64/1 + +65/1 + +66 + +67 + +601 13 December 2012 + +Interfacing with COBOL B.4 + + Ada Reference Manual — 2012 Edition + +68 + +69 + +70 + +71/1 + +72 + +73 + +74 + +75 + +76 + +77 + +78 + +79/1 + +80 + +81 + +82 + +83 + +84 + +85 + +86 + +87/1 + +function To_Decimal (Item : in Numeric; + Format : in Display_Format) return Num; + +Produces a value of type Num corresponding to Item as represented by Format. The number of +digits after the assumed radix point in Item is Num'Scale. Conversion_Error is propagated if the +value represented by Item is outside the range of Num. + +function To_Display (Item : in Num; + Format : in Display_Format) return Numeric; + +This function returns the Numeric value for Item, represented in accordance with Format. The +length of the returned value is Length(Format), and the lower bound is 1. Conversion_Error is +propagated if Num is negative and Format is Unsigned. + +function Valid (Item : in Packed_Decimal; + Format : in Packed_Format) return Boolean; + +This function returns True if Item has a value consistent with Format, and False otherwise. The +rules for the formation of Packed_Decimal values are implementation defined. + +function Length (Format : in Packed_Format) return Natural; + +This function returns the minimal length of a Packed_Decimal value sufficient to hold any value +of type Num when represented as Format. + +function To_Decimal (Item : in Packed_Decimal; + Format : in Packed_Format) return Num; + +Produces a value of type Num corresponding to Item as represented by Format. Num'Scale is the +number of digits after the assumed radix point in Item. Conversion_Error is propagated if the +value represented by Item is outside the range of Num. + +function To_Packed (Item : in Num; + Format : in Packed_Format) return Packed_Decimal; + +This function returns the Packed_Decimal value for Item, represented in accordance with +Format. The length of the returned value is Length(Format), and the lower bound is 1. +Conversion_Error is propagated if Num is negative and Format is Packed_Unsigned. + +function Valid (Item : in Byte_Array; + Format : in Binary_Format) return Boolean; + +This function returns True if Item has a value consistent with Format, and False otherwise. + +function Length (Format : in Binary_Format) return Natural; + +This function returns the minimal length of a Byte_Array value sufficient to hold any value of +type Num when represented as Format. + +function To_Decimal (Item : in Byte_Array; + Format : in Binary_Format) return Num; + +Produces a value of type Num corresponding to Item as represented by Format. Num'Scale is the +number of digits after the assumed radix point in Item. Conversion_Error is propagated if the +value represented by Item is outside the range of Num. + +function To_Binary (Item : in Num; + Format : in Binary_Format) return Byte_Array; + +This function returns the Byte_Array value for Item, represented in accordance with Format. The +length of the returned value is Length(Format), and the lower bound is 1. + +B.4 Interfacing with COBOL + +13 December 2012 602 + + Ada Reference Manual — 2012 Edition + +function To_Decimal (Item : in Binary) return Num; + +function To_Decimal (Item : in Long_Binary) return Num; + +These functions convert from COBOL binary format to a corresponding value of the decimal +type Num. Conversion_Error is propagated if Item is too large for Num. + +function To_Binary (Item : in Num) return Binary; + +function To_Long_Binary (Item : in Num) return Long_Binary; + +These functions convert from Ada decimal to COBOL binary format. Conversion_Error is +propagated if the value of Item is too large to be represented in the result type. + +88 + +89 + +90 + +91 + +An implementation shall support specifying aspect Convention with a COBOL convention_identifier for a +COBOL-eligible type (see B.1). + +92/3 + +Implementation Requirements + +Implementation Permissions + +An implementation may provide additional constants of the private types Display_Format, Binary_Format, +or Packed_Format. + +An implementation may provide further floating point and integer types in Interfaces.COBOL to match +additional native COBOL types, and may also supply corresponding conversion functions in the generic +package Decimal_Conversions. + +Implementation Advice + +An Ada implementation should support the following interface correspondences between Ada and +COBOL. + +• An Ada access T parameter is passed as a “BY REFERENCE” data item of the COBOL type + +corresponding to T. + +• An Ada in scalar parameter is passed as a “BY CONTENT” data item of the corresponding + +COBOL type. + +• Any other Ada parameter is passed as a “BY REFERENCE” data item of the COBOL type +corresponding to the Ada parameter type; for scalars, a local copy is used if necessary to ensure +by-copy semantics. + +NOTES +12 An implementation is not required to support specifying aspect Convention for access types, nor is it required to +support specifying aspects Import, Export, or Convention for functions. + +13 If an Ada subprogram is exported to COBOL, then a call from COBOL call may specify either “BY CONTENT” or +“BY REFERENCE”. + +93 + +94 + +95 + +96 + +97 + +98 + +99/3 + +100 + +603 13 December 2012 + +Interfacing with COBOL B.4 + + + + 101 + +102 + +103 + +104 + +105 + +106/3 + +107/3 + +108 + +109 + +110 + +111 + +112 + +113 + +114 + +115/3 + +Ada Reference Manual — 2012 Edition + +Examples of Interfaces.COBOL: + +Examples + +with Interfaces.COBOL; +procedure Test_Call is + -- Calling a foreign COBOL program + -- Assume that a COBOL program PROG has the following declaration + -- in its LINKAGE section: + -- 01 Parameter-Area + -- 05 NAME PIC X(20). + -- 05 SSN PIC X(9). + -- 05 SALARY PIC 99999V99 USAGE COMP. + -- The effect of PROG is to update SALARY based on some algorithm + package COBOL renames Interfaces.COBOL; + type Salary_Type is delta 0.01 digits 7; + type COBOL_Record is + record + Name : COBOL.Numeric(1..20); + SSN : COBOL.Numeric(1..9); + Salary : COBOL.Binary; -- Assume Binary = 32 bits + end record + with Convention => COBOL; + procedure Prog (Item : in out COBOL_Record) + with Import => True, Convention => COBOL; + package Salary_Conversions is + new COBOL.Decimal_Conversions(Salary_Type); + Some_Salary : Salary_Type := 12_345.67; + Some_Record : COBOL_Record := + (Name => "Johnson, John ", + SSN => "111223333", + Salary => Salary_Conversions.To_Binary(Some_Salary)); +begin + Prog (Some_Record); + ... +end Test_Call; +with Interfaces.COBOL; +with COBOL_Sequential_IO; -- Assumed to be supplied by implementation +procedure Test_External_Formats is + -- Using data created by a COBOL program + -- Assume that a COBOL program has created a sequential file with + -- the following record structure, and that we need to + -- process the records in an Ada program + -- 01 EMPLOYEE-RECORD + -- 05 NAME PIC X(20). + -- 05 SSN PIC X(9). + -- 05 SALARY PIC 99999V99 USAGE COMP. + -- 05 ADJUST PIC S999V999 SIGN LEADING SEPARATE. + -- The COMP data is binary (32 bits), high-order byte first + package COBOL renames Interfaces.COBOL; + type Salary_Type is delta 0.01 digits 7; + type Adjustments_Type is delta 0.001 digits 6; + type COBOL_Employee_Record_Type is -- External representation + record + Name : COBOL.Alphanumeric(1..20); + SSN : COBOL.Alphanumeric(1..9); + Salary : COBOL.Byte_Array(1..4); + Adjust : COBOL.Numeric(1..7); -- Sign and 6 digits + end record + with Convention => COBOL; + +B.4 Interfacing with COBOL + +13 December 2012 604 + + Ada Reference Manual — 2012 Edition + + package COBOL_Employee_IO is + new COBOL_Sequential_IO(COBOL_Employee_Record_Type); + use COBOL_Employee_IO; + COBOL_File : File_Type; + type Ada_Employee_Record_Type is -- Internal representation + record + Name : String(1..20); + SSN : String(1..9); + Salary : Salary_Type; + Adjust : Adjustments_Type; + end record; + COBOL_Record : COBOL_Employee_Record_Type; + Ada_Record : Ada_Employee_Record_Type; + package Salary_Conversions is + new COBOL.Decimal_Conversions(Salary_Type); + use Salary_Conversions; + package Adjustments_Conversions is + new COBOL.Decimal_Conversions(Adjustments_Type); + use Adjustments_Conversions; +begin + Open (COBOL_File, Name => "Some_File"); + loop + Read (COBOL_File, COBOL_Record); + + Ada_Record.Name := To_Ada(COBOL_Record.Name); + Ada_Record.SSN := To_Ada(COBOL_Record.SSN); + Ada_Record.Salary := + To_Decimal(COBOL_Record.Salary, COBOL.High_Order_First); + Ada_Record.Adjust := + To_Decimal(COBOL_Record.Adjust, COBOL.Leading_Separate); + ... -- Process Ada_Record + end loop; +exception + when End_Error => ... +end Test_External_Formats; + +B.5 Interfacing with Fortran + +The facilities relevant to interfacing with the Fortran language are the package Interfaces.Fortran and +support for specifying the Convention aspect with convention_identifier Fortran. + +The package Interfaces.Fortran defines Ada types whose representations are identical to the default +representations of the Fortran intrinsic types Integer, Real, Double Precision, Complex, Logical, and +Character in a supported Fortran implementation. These Ada types can therefore be used to pass objects +between Ada and Fortran programs. + +The library package Interfaces.Fortran has the following declaration: + +Static Semantics + +with Ada.Numerics.Generic_Complex_Types; -- see G.1.1 +pragma Elaborate_All(Ada.Numerics.Generic_Complex_Types); +package Interfaces.Fortran is + pragma Pure(Fortran); + type Fortran_Integer is range implementation-defined; + type Real is digits implementation-defined; + type Double_Precision is digits implementation-defined; + type Logical is new Boolean; + +605 13 December 2012 + +Interfacing with COBOL B.4 + +116 + +117 + +118 + +119 + +120 + +121 + +122 + +123 + +124 + +1/3 + +2 + +3 + +4 + +5 + +6 + +7 + + Ada Reference Manual — 2012 Edition + +8 + +9 + +10 + +11 + +12/3 + +13 + +14 + +15 + +16 + +17 + +18 + +19 + + package Single_Precision_Complex_Types is + new Ada.Numerics.Generic_Complex_Types (Real); + type Complex is new Single_Precision_Complex_Types.Complex; + subtype Imaginary is Single_Precision_Complex_Types.Imaginary; + i : Imaginary renames Single_Precision_Complex_Types.i; + j : Imaginary renames Single_Precision_Complex_Types.j; + type Character_Set is implementation-defined character type; + type Fortran_Character is array (Positive range <>) of Character_Set + with Pack; + function To_Fortran (Item : in Character) return Character_Set; + function To_Ada (Item : in Character_Set) return Character; + function To_Fortran (Item : in String) return Fortran_Character; + function To_Ada (Item : in Fortran_Character) return String; + procedure To_Fortran (Item : in String; + Target : out Fortran_Character; + Last : out Natural); + procedure To_Ada (Item : in Fortran_Character; + Target : out String; + Last : out Natural); +end Interfaces.Fortran; + +The types Fortran_Integer, Real, Double_Precision, Logical, Complex, and Fortran_Character are Fortran- +compatible. + +The To_Fortran and To_Ada functions map between the Ada type Character and the Fortran type +Character_Set, and also between the Ada type String and the Fortran type Fortran_Character. The +To_Fortran and To_Ada procedures have analogous effects to the string conversion subprograms found in +Interfaces.COBOL. + +20/3 + +An implementation shall support specifying aspect Convention with a Fortran convention_identifier for a +Fortran-eligible type (see B.1). + +Implementation Requirements + +21 + +22 + +23 + +24 + +25 + +Implementation Permissions + +An implementation may add additional declarations to the Fortran interface packages. For example, the +Fortran interface package for an implementation of Fortran 77 (ANSI X3.9-1978) that defines types like +Integer*n, Real*n, Logical*n, and Complex*n may contain the declarations of types named Integer_- +Star_n, Real_Star_n, Logical_Star_n, and Complex_Star_n. (This convention should not apply to +Character*n, for which the Ada analog is the constrained array subtype Fortran_Character (1..n).) +Similarly, the Fortran interface package for an implementation of Fortran 90 that provides multiple kinds +of intrinsic types, e.g. Integer (Kind=n), Real (Kind=n), Logical (Kind=n), Complex (Kind=n), and +Character (Kind=n), may contain the declarations of types with the recommended names Integer_Kind_n, +Real_Kind_n, Logical_Kind_n, Complex_Kind_n, and Character_Kind_n. + +Implementation Advice + +An Ada implementation should support the following interface correspondences between Ada and Fortran: + +• An Ada procedure corresponds to a Fortran subroutine. +• An Ada function corresponds to a Fortran function. +• An Ada parameter of an elementary, array, or record type T is passed as a TF argument to a +Fortran procedure, where TF is the Fortran type corresponding to the Ada type T, and where the +INTENT attribute of the corresponding dummy argument matches the Ada formal parameter + +B.5 Interfacing with Fortran + +13 December 2012 606 + + Ada Reference Manual — 2012 Edition + +mode; the Fortran implementation's parameter passing conventions are used. For elementary +types, a local copy is used if necessary to ensure by-copy semantics. + +• An Ada parameter of an access-to-subprogram type is passed as a reference to a Fortran + +procedure whose interface corresponds to the designated subprogram's specification. + +NOTES +14 An object of a Fortran-compatible record type, declared in a library package or subprogram, can correspond to a +Fortran common block; the type also corresponds to a Fortran “derived type”. + +Example of Interfaces.Fortran: + +Examples + +with Interfaces.Fortran; +use Interfaces.Fortran; +procedure Ada_Application is + type Fortran_Matrix is array (Integer range <>, + Integer range <>) of Double_Precision + with Convention => Fortran; -- stored in Fortran's + -- column-major order + procedure Invert (Rank : in Fortran_Integer; X : in out Fortran_Matrix) + with Import => True, Convention => Fortran; -- a Fortran subroutine + Rank : constant Fortran_Integer := 100; + My_Matrix : Fortran_Matrix (1 .. Rank, 1 .. Rank); +begin + ... + My_Matrix := ...; + ... + Invert (Rank, My_Matrix); + ... +end Ada_Application; + +26 + +27 + +28 + +29 + +30/3 + +31 + +32 + +33 + +34 + +607 13 December 2012 + +Interfacing with Fortran B.5 + + Ada Reference Manual — 2012 Edition + +Annex C +(normative) +Systems Programming + +The Systems Programming Annex specifies additional capabilities provided for low-level programming. +These capabilities are also required in many real-time, embedded, distributed, and information systems. + +1 + +C.1 Access to Machine Operations + +This subclause specifies rules regarding access to machine instructions from within an Ada program. + +1/3 + +The implementation shall support machine code insertions (see 13.8) or intrinsic subprograms (see 6.3.1) +(or both). Implementation-defined attributes shall be provided to allow the use of Ada entities as operands. + +Implementation Requirements + +Implementation Advice + +The machine code or intrinsics support should allow access to all operations normally available to +assembly language programmers for the target environment, including privileged instructions, if any. + +The support for interfacing aspects (see Annex B) should include interface to assembler; the default +assembler should be associated with the convention identifier Assembler. + +If an entity is exported to assembly language, then the implementation should allocate it at an addressable +location, and should ensure that it is retained by the linking process, even if not otherwise referenced from +the Ada code. The implementation should assume that any call to a machine code or assembler +subprogram is allowed to read or update every object that is specified as exported. + +Documentation Requirements + +The implementation shall document the overhead associated with calling machine-code or intrinsic +subprograms, as compared to a fully-inlined call, and to a regular out-of-line call. + +The implementation shall document the types of the package System.Machine_Code usable for machine +code insertions, and the attributes to be used in machine code insertions for references to Ada entities. + +The implementation shall document the subprogram calling conventions associated with the convention +identifiers available for use with the Convention aspect (Ada and Assembler, at a minimum), including +register saving, exception propagation, parameter passing, and function value returning. + +For exported and imported subprograms, the implementation shall document the mapping between the +Link_Name string, if specified, or the Ada designator, if not, and the external link name used for such a +subprogram. + +Implementation Advice + +The implementation should ensure that little or no overhead is associated with calling intrinsic and +machine-code subprograms. + +It is recommended that intrinsic subprograms be provided for convenient access to any machine operations +that provide special capabilities or efficiency and that are not otherwise available through the language +constructs. Examples of such instructions include: + +2 + +3 + +4/3 + +5 + +6 + +7 + +8/3 + +9 + +10 + +11 + +609 13 December 2012 + +Systems Programming C + + 12 + +13 + +14 + +15 + +16 + +Ada Reference Manual — 2012 Edition + +• Atomic read-modify-write operations — e.g., test and set, compare and swap, decrement and + +test, enqueue/dequeue. + +• Standard numeric functions — e.g., sin, log. +• String manipulation operations — e.g., translate and test. +• Vector operations — e.g., compare vector against thresholds. +• Direct operations on I/O ports. + +C.2 Required Representation Support + +1/3 + +This subclause specifies minimal requirements on the support for representation items and related features. + +2/3 + +The implementation shall support at least the functionality defined by the recommended levels of support +in Clause 13. + +Implementation Requirements + +C.3 Interrupt Support + +1/3 + +This subclause specifies the language-defined model for hardware interrupts in addition to mechanisms for +handling interrupts. + +Dynamic Semantics + +2 + +3 + +4 + +5 + +6 + +7 + +An interrupt represents a class of events that are detected by the hardware or the system software. +Interrupts are said to occur. An occurrence of an interrupt is separable into generation and delivery. +Generation of an interrupt is the event in the underlying hardware or system that makes the interrupt +available to the program. Delivery is the action that invokes part of the program as response to the +interrupt occurrence. Between generation and delivery, the interrupt occurrence (or interrupt) is pending. +Some or all interrupts may be blocked. When an interrupt is blocked, all occurrences of that interrupt are +prevented from being delivered. Certain interrupts are reserved. The set of reserved interrupts is +implementation defined. A reserved interrupt is either an interrupt for which user-defined handlers are not +supported, or one which already has an attached handler by some other implementation-defined means. +Program units can be connected to nonreserved interrupts. While connected, the program unit is said to be +attached to that interrupt. The execution of that program unit, the interrupt handler, is invoked upon +delivery of the interrupt occurrence. + +While a handler is attached to an interrupt, it is called once for each delivered occurrence of that interrupt. +While the handler executes, the corresponding interrupt is blocked. + +While an interrupt is blocked, all occurrences of that interrupt are prevented from being delivered. +Whether such occurrences remain pending or are lost is implementation defined. + +Each interrupt has a default treatment which determines the system's response to an occurrence of that +interrupt when no user-defined handler is attached. The set of possible default treatments is +implementation defined, as is the method (if one exists) for configuring the default treatments for +interrupts. + +An interrupt is delivered to the handler (or default treatment) that is in effect for that interrupt at the time +of delivery. + +An exception propagated from a handler that is invoked by an interrupt has no effect. + +C.1 Access to Machine Operations + +13 December 2012 610 + + Ada Reference Manual — 2012 Edition + +If the Ceiling_Locking policy (see D.3) is in effect, the interrupt handler executes with the active priority +that is the ceiling priority of the corresponding protected object. + +Implementation Requirements + +The implementation shall provide a mechanism to determine the minimum stack space that is needed for +each interrupt handler and to reserve that space for the execution of the handler. This space should +accommodate nested invocations of the handler where the system permits this. + +If the hardware or the underlying system holds pending interrupt occurrences, the implementation shall +provide for later delivery of these occurrences to the program. + +If the Ceiling_Locking policy is not in effect, the implementation shall provide means for the application +to specify whether interrupts are to be blocked during protected actions. + +The implementation shall document the following items: + +Documentation Requirements + +1. For each interrupt, which interrupts are blocked from delivery when a handler attached to that +interrupt executes (either as a result of an interrupt delivery or of an ordinary call on a procedure +of the corresponding protected object). + +2. Any interrupts that cannot be blocked, and the effect of attaching handlers to such interrupts, if + +this is permitted. + +3. Which run-time stack an interrupt handler uses when it executes as a result of an interrupt +delivery; if this is configurable, what is the mechanism to do so; how to specify how much space +to reserve on that stack. + +4. Any implementation- or hardware-specific activity that happens before a user-defined interrupt + +handler gets control (e.g., reading device registers, acknowledging devices). + +5. Any timing or other limitations imposed on the execution of interrupt handlers. + +6. The state (blocked/unblocked) of the nonreserved interrupts when the program starts; if some +interrupts are unblocked, what is the mechanism a program can use to protect itself before it can +attach the corresponding handlers. + +7. Whether the interrupted task is allowed to resume execution before the interrupt handler returns. + +8. The treatment of interrupt occurrences that are generated while the interrupt is blocked; i.e., + +whether one or more occurrences are held for later delivery, or all are lost. + +9. Whether predefined or implementation-defined exceptions are raised as a result of the +occurrence of any interrupt, and the mapping between the machine interrupts (or traps) and the +predefined exceptions. + +10. + On a multi-processor, the rules governing the delivery of an interrupt to a particular processor. + +Implementation Permissions + +If the underlying system or hardware does not allow interrupts to be blocked, then no blocking is required +as part of the execution of subprograms of a protected object for which one of its subprograms is an +interrupt handler. + +In a multi-processor with more than one interrupt subsystem, it is implementation defined whether (and +how) interrupt sources from separate subsystems share the same Interrupt_Id type (see C.3.2). In +particular, the meaning of a blocked or pending interrupt may then be applicable to one processor only. + +8 + +9 + +10 + +11 + +12 + +13 + +14 + +15 + +16 + +17 + +18 + +19 + +20 + +21 + +22 + +23/2 + +24 + +611 13 December 2012 + +Interrupt Support C.3 + + Ada Reference Manual — 2012 Edition + +25 + +Implementations are allowed to impose timing or other limitations on the execution of interrupt handlers. + +26/3 + +27 + +28/2 + +29 + +30 + +31 + +Other forms of handlers are allowed to be supported, in which case the rules of this subclause should be +adhered to. + +The active priority of the execution of an interrupt handler is allowed to vary from one occurrence of the +same interrupt to another. + +If the Ceiling_Locking policy is not in effect, the implementation should provide means for the application +to specify which interrupts are to be blocked during protected actions, if the underlying system allows for +finer-grained control of interrupt blocking. + +Implementation Advice + +NOTES +1 The default treatment for an interrupt can be to keep the interrupt pending or to deliver it to an implementation-defined +handler. Examples of actions that an implementation-defined handler is allowed to perform include aborting the partition, +ignoring (i.e., discarding occurrences of) the interrupt, or queuing one or more occurrences of the interrupt for possible +later delivery when a user-defined handler is attached to that interrupt. + +2 It is a bounded error to call Task_Identification.Current_Task (see C.7.1) from an interrupt handler. + +3 The rule that an exception propagated from an interrupt handler has no effect is modeled after the rule about exceptions +propagated out of task bodies. + +C.3.1 Protected Procedure Handlers + +Paragraphs 1 through 6 were moved to Annex J, “Obsolescent Features”. + +Static Semantics + +6.1/3 + +For a parameterless protected procedure, the following language-defined representation aspects may be +specified: + +6.2/3 + +Interrupt_Handler + + The type of aspect Interrupt_Handler is Boolean. If directly specified, the aspect_definition +shall be a static expression. This aspect is never inherited; if not directly specified, the +aspect is False. + +6.3/3 + +Attach_Handler + +aspect Attach_Handler + + The +Interrupts.Interrupt_Id. This aspect is never inherited. + +is + +an expression, which + +shall be of + +type + +7/3 + +If either the Attach_Handler or Interrupt_Handler aspect are specified for a protected procedure, the +corresponding protected_type_declaration or single_protected_declaration shall be a library-level +declaration and shall not be declared within a generic body. In addition to the places where Legality Rules +normally apply (see 12.3), this rule also applies in the private part of an instance of a generic unit. + +Legality Rules + +8/3 + +This paragraph was deleted. + +9/3 + +If the Interrupt_Handler aspect of a protected procedure is True, then the procedure may be attached +dynamically, as a handler, to interrupts (see C.3.2). Such procedures are allowed to be attached to multiple +interrupts. + +Dynamic Semantics + +C.3 Interrupt Support + +13 December 2012 612 + + + + Ada Reference Manual — 2012 Edition + +The expression specified for the Attach_Handler aspect of a protected procedure P is evaluated as part of +the creation of the protected object that contains P. The value of the expression identifies an interrupt. As +part of the initialization of that object, P (the handler procedure) is attached to the identified interrupt. A +check is made that the corresponding interrupt is not reserved. Program_Error is raised if the check fails, +and the existing treatment for the interrupt is not affected. + +If the Ceiling_Locking policy (see D.3) is in effect, then upon the initialization of a protected object that +contains a protected procedure for which either the Attach_Handler aspect is specified or the +Interrupt_Handler aspect is True, a check is made that the initial ceiling priority of the object is in the +range of System.Interrupt_Priority. If the check fails, Program_Error is raised. + +When a protected object is finalized, for any of its procedures that are attached to interrupts, the handler is +detached. If the handler was attached by a procedure in the Interrupts package or if no user handler was +previously attached to the interrupt, the default treatment is restored. If the Attach_Handler aspect was +specified and the most recently attached handler for the same interrupt is the same as the one that was +attached at the time the protected object was initialized, the previous handler is restored. + +When a handler is attached to an interrupt, the interrupt is blocked (subject to the Implementation +Permission in C.3) during the execution of every protected action on the protected object containing the +handler. + +If the Ceiling_Locking policy (see D.3) is in effect and an interrupt is delivered to a handler, and the +interrupt hardware priority is higher than the ceiling priority of the corresponding protected object, the +execution of the program is erroneous. + +Erroneous Execution + +10/3 + +11/3 + +12/3 + +13 + +14 + +If the handlers for a given interrupt attached via aspect Attach_Handler are not attached and detached in a +stack-like (LIFO) order, program execution is erroneous. In particular, when a protected object is +finalized, the execution is erroneous if any of the procedures of the protected object are attached to +interrupts via aspect Attach_Handler and the most recently attached handler for the same interrupt is not +the same as the one that was attached at the time the protected object was initialized. + +14.1/3 + +The following metric shall be documented by the implementation: + +Metrics + +• The worst-case overhead for an interrupt handler that is a parameterless protected procedure, in +clock cycles. This is the execution time not directly attributable to the handler procedure or the +interrupted execution. It is estimated as C – (A+B), where A is how long it takes to complete a +given sequence of instructions without any interrupt, B is how long it takes to complete a normal +call to a given protected procedure, and C is how long it takes to complete the same sequence of +instructions when it is interrupted by one execution of the same procedure called via an +interrupt. + +Implementation Permissions + +When the aspects Attach_Handler or Interrupt_Handler are specified for a protected procedure, the +implementation is allowed to impose implementation-defined restrictions on the corresponding +protected_type_declaration and protected_body. + +An implementation may use a different mechanism for invoking a protected procedure in response to a +hardware interrupt than is used for a call to that protected procedure from a task. + +Notwithstanding what this subclause says elsewhere, the Attach_Handler and Interrupt_Handler aspects +are allowed to be used for other, implementation defined, forms of interrupt handlers. + +15 + +16/2 + +17/3 + +18 + +19/3 + +613 13 December 2012 + +Protected Procedure Handlers C.3.1 + + Ada Reference Manual — 2012 Edition + +Implementation Advice + +Whenever possible, the implementation should allow interrupt handlers to be called directly by the +hardware. + +Whenever practical, the implementation should detect violations of any implementation-defined +restrictions before run time. + +NOTES +4 The Attach_Handler aspect may provide static attachment of handlers to interrupts if the implementation supports +preelaboration of protected objects. (See C.4.) + +5 A protected object that has a (protected) procedure attached to an interrupt should have a ceiling priority at least as high +as the highest processor priority at which that interrupt will ever be delivered. + +6 Protected procedures can also be attached dynamically to interrupts via operations declared in the predefined package +Interrupts. + +7 An example of a possible implementation-defined restriction is disallowing the use of the standard storage pools within +the body of a protected procedure that is an interrupt handler. + +C.3.2 The Package Interrupts + +The following language-defined packages exist: + +Static Semantics + +with System; +with System.Multiprocessors; +package Ada.Interrupts is + type Interrupt_Id is implementation-defined; + type Parameterless_Handler is + access protected procedure; +This paragraph was deleted. + function Is_Reserved (Interrupt : Interrupt_Id) + return Boolean; + function Is_Attached (Interrupt : Interrupt_Id) + return Boolean; + function Current_Handler (Interrupt : Interrupt_Id) + return Parameterless_Handler; + procedure Attach_Handler + (New_Handler : in Parameterless_Handler; + Interrupt : in Interrupt_Id); + procedure Exchange_Handler + (Old_Handler : out Parameterless_Handler; + New_Handler : in Parameterless_Handler; + Interrupt : in Interrupt_Id); + procedure Detach_Handler + (Interrupt : in Interrupt_Id); + function Reference (Interrupt : Interrupt_Id) + return System.Address; + function Get_CPU (Interrupt : Interrupt_Id) + return System.Multiprocessors.CPU_Range; +private + ... -- not specified by the language +end Ada.Interrupts; + +20 + +21 + +22/3 + +23/2 + +24 + +25 + +1 + +2/3 + +3/1 + +4 + +5 + +6 + +7 + +8 + +9 + +10 + +10.1/3 + +11 + +C.3.1 Protected Procedure Handlers + +13 December 2012 614 + + Ada Reference Manual — 2012 Edition + +package Ada.Interrupts.Names is + implementation-defined : constant Interrupt_Id := + implementation-defined; + . . . + implementation-defined : constant Interrupt_Id := + implementation-defined; +end Ada.Interrupts.Names; + +Dynamic Semantics + +The Interrupt_Id type is an implementation-defined discrete type used to identify interrupts. + +The Is_Reserved function returns True if and only if the specified interrupt is reserved. + +The Is_Attached function returns True if and only if a user-specified interrupt handler is attached to the +interrupt. + +The Current_Handler function returns a value that represents the attached handler of the interrupt. If no +user-defined handler is attached to the interrupt, Current_Handler returns null. + +The Attach_Handler procedure attaches the specified handler to the interrupt, overriding any existing +treatment (including a user handler) in effect for that interrupt. If New_Handler is null, the default +treatment is restored. If New_Handler designates a protected procedure for which the aspect Interrupt_- +Handler is False, Program_Error is raised. In this case, the operation does not modify the existing interrupt +treatment. + +The Exchange_Handler procedure operates in the same manner as Attach_Handler with the addition that +the value returned in Old_Handler designates the previous treatment for the specified interrupt. If the +previous treatment is not a user-defined handler, null is returned. + +The Detach_Handler procedure restores the default treatment for the specified interrupt. + +For all operations defined in this package that take a parameter of type Interrupt_Id, with the exception of +Is_Reserved and Reference, a check is made that the specified interrupt is not reserved. Program_Error is +raised if this check fails. + +If, by using the Attach_Handler, Detach_Handler, or Exchange_Handler procedures, an attempt is made to +detach a handler that was attached statically (using the aspect Attach_Handler), the handler is not detached +and Program_Error is raised. + +The Reference function returns a value of type System.Address that can be used to attach a task entry via +an address clause (see J.7.1) to the interrupt specified by Interrupt. This function raises Program_Error if +attaching task entries to interrupts (or to this particular interrupt) is not supported. + +12 + +13 + +14 + +15 + +16/1 + +17/3 + +18/1 + +19 + +20 + +21/3 + +22/2 + +The function Get_CPU returns the processor on which the handler for Interrupt is executed. If the handler +can execute on more than one processor the value System.Multiprocessors.Not_A_Specific_CPU is +returned. + +22.1/3 + +At no time during attachment or exchange of handlers shall the current handler of the corresponding +interrupt be undefined. + +23 + +Implementation Requirements + +If the Ceiling_Locking policy (see D.3) is in effect, the implementation shall document the default ceiling +priority assigned to a protected object that contains a protected procedure that specifies either the + +24/3 + +Documentation Requirements + +615 13 December 2012 + +The Package Interrupts C.3.2 + + Ada Reference Manual — 2012 Edition + +Attach_Handler or Interrupt_Handler aspects, but does not specify the Interrupt_Priority aspect. This +default need not be the same for all interrupts. + +Implementation Advice + +25 + +26 + +If implementation-defined forms of interrupt handler procedures are supported, such as protected +procedures with parameters, then for each such form of a handler, a type analogous to Parameterless_- +Handler should be specified in a child package of Interrupts, with the same operations as in the predefined +package Interrupts. + +NOTES +8 The package Interrupts.Names contains implementation-defined names (and constant values) for the interrupts that are +supported by the implementation. + +27 + +Example of interrupt handlers: + +Examples + +28/3 + +Device_Priority : constant + array (1..5) of System.Interrupt_Priority := ( ... ); +protected type Device_Interface + (Int_Id : Ada.Interrupts.Interrupt_Id) + with Interrupt_Priority => Device_Priority(Int_Id) is + procedure Handler + with Attach_Handler => Int_Id; + ... + end Device_Interface; + ... +Device_1_Driver : Device_Interface(1); + ... +Device_5_Driver : Device_Interface(5); + ... + +C.4 Preelaboration Requirements + +1/3 + +This subclause specifies additional implementation and documentation requirements for the Preelaborate +pragma (see 10.2.1). + +Implementation Requirements + +2 + +3 + +4 + +The implementation shall not incur any run-time overhead for the elaboration checks of subprograms and +protected_bodies declared in preelaborated library units. + +The implementation shall not execute any memory write operations after load time for the elaboration of +constant objects declared immediately within the declarative region of a preelaborated library package, so +long as the subtype and initial expression (or default initial expressions if initialized by default) of the +object_declaration satisfy the following restrictions. The meaning of load time is implementation defined. + +• Any subtype_mark denotes a statically constrained subtype, with statically constrained + +subcomponents, if any; + +4.1/2 + +• no subtype_mark denotes a controlled type, a private type, a private extension, a generic formal + +private type, a generic formal derived type, or a descendant of such a type; + +5 + +6 + +7 + +• any constraint is a static constraint; +• any allocator is for an access-to-constant type; +• any uses of predefined operators appear only within static expressions; + +C.3.2 The Package Interrupts + +13 December 2012 616 + + Ada Reference Manual — 2012 Edition + +• any primaries that are names, other than attribute_references for the Access or Address + +attributes, appear only within static expressions; + +• any name that is not part of a static expression is an expanded name or direct_name that + +statically denotes some entity; + +• any discrete_choice of an array_aggregate is static; +• no language-defined check associated with the elaboration of the object_declaration can fail. + +Documentation Requirements + +The implementation shall document any circumstances under which the elaboration of a preelaborated +package causes code to be executed at run time. + +The implementation shall document whether the method used for initialization of preelaborated variables +allows a partition to be restarted without reloading. + +It is recommended that preelaborated packages be implemented in such a way that there should be little or +no code executed at run time for the elaboration of entities not already covered by the Implementation +Requirements. + +Implementation Advice + +C.5 Pragma Discard_Names + +A pragma Discard_Names may be used to request a reduction in storage used for the names of certain +entities. + +The form of a pragma Discard_Names is as follows: + pragma Discard_Names[([On => ] local_name)]; + +Syntax + +A pragma Discard_Names is allowed only immediately within a declarative_part, immediately +within a package_specification, or as a configuration pragma. + +Legality Rules + +The local_name (if present) shall denote a nonderived enumeration first subtype, a tagged first subtype, or +an exception. The pragma applies to the type or exception. Without a local_name, the pragma applies to +all such entities declared after the pragma, within the same declarative region. Alternatively, the pragma +can be used as a configuration pragma. If the pragma applies to a type, then it applies also to all +descendants of the type. + +If a local_name is given, then a pragma Discard_Names is a representation pragma. + +Static Semantics + +If the pragma applies to an enumeration type, then the semantics of the Wide_Wide_Image and +Wide_Wide_Value attributes are implementation defined for that type; the semantics of Image, +Wide_Image, Value, and Wide_Value are still defined +terms of Wide_Wide_Image and +Wide_Wide_Value. In addition, the semantics of Text_IO.Enumeration_IO are implementation defined. If +the pragma applies to a tagged type, then the semantics of the Tags.Wide_Wide_Expanded_Name function +are implementation defined for that type; the semantics of Tags.Expanded_Name and Tags.Wide_- +Expanded_Name are still defined in terms of Tags.Wide_Wide_Expanded_Name. If the pragma applies to +the Exceptions.Wide_Wide_Exception_Name function are +an exception, + +the semantics of + +then + +in + +8 + +9 + +10 + +11 + +12 + +13 + +14 + +1 + +2 + +3 + +4 + +5 + +6 + +7/2 + +617 13 December 2012 + +Preelaboration Requirements C.4 + + Ada Reference Manual — 2012 Edition + +implementation defined for that exception; the semantics of Exceptions.Exception_Name and Exceptions.- +Wide_Exception_Name are still defined in terms of Exceptions.Wide_Wide_Exception_Name. + +8 + +If the pragma applies to an entity, then the implementation should reduce the amount of storage used for +storing names associated with that entity. + +Implementation Advice + +C.6 Shared Variable Control + +1/3 + +This subclause defines representation aspects that control the use of shared variables. + +Paragraphs 2 through 6 were moved to Annex J, “Obsolescent Features”. + +6.1/3 + +For an object_declaration, a component_declaration, or a full_type_declaration, the following +representation aspects may be specified: + +Static Semantics + +6.2/3 + +Atomic + +The type of aspect Atomic is Boolean. + +6.3/3 + +Independent The type of aspect Independent is Boolean. + +6.4/3 + +Volatile + +The type of aspect Volatile is Boolean. + +6.5/3 + +For a full_type_declaration of an array type (including the anonymous type of an object_declaration of an +anonymous array object), the following representation aspects may be specified: + +6.6/3 + +Atomic_Components + +The type of aspect Atomic_Components is Boolean. + +6.7/3 + +Volatile_Components + +The type of aspect Volatile_Components is Boolean. + +6.8/3 + +For a full_type_declaration (including the anonymous type of an object_declaration of an anonymous +array object), the following representation aspect may be specified: + +6.9/3 + +Independent_Components + +The type of aspect Independent_Components is Boolean. + +6.10/3 + +If any of these aspects are directly specified, the aspect_definition shall be a static expression. If not +specified (including by inheritance), each of these aspects is False. + +7/3 + +8/3 + +An atomic type is one for which the aspect Atomic is True. An atomic object (including a component) is +one for which the aspect Atomic is True, or a component of an array for which the aspect +Atomic_Components is True for the associated type, or any object of an atomic type, other than objects +obtained by evaluating a slice. + +A volatile type is one for which the aspect Volatile is True. A volatile object (including a component) is +one for which the aspect Volatile is True, or a component of an array for which the aspect Volatile_- +Components is True for the associated type, or any object of a volatile type. In addition, every atomic type +or object is also defined to be volatile. Finally, if an object is volatile, then so are all of its subcomponents +(the same does not apply to atomic). + +8.1/3 + +When True, the aspects Independent and Independent_Components specify as independently addressable +the named object or component(s), or in the case of a type, all objects or components of that type. All +atomic objects are considered to be specified as independently addressable. + +C.5 Pragma Discard_Names + +13 December 2012 618 + + + + + Ada Reference Manual — 2012 Edition + +Paragraph 9 was moved to Annex J, “Obsolescent Features”. + +Legality Rules + +If aspect Independent_Components is specified for a full_type_declaration, the declaration shall be that of +an array or record type. + +It is illegal to specify either of the aspects Atomic or Atomic_Components to have the value True for an +object or type if the implementation cannot support the indivisible reads and updates required by the +aspect (see below). + +It is illegal to specify the Size attribute of an atomic object, the Component_Size attribute for an array type +with atomic components, or the layout attributes of an atomic component, in a way that prevents the +implementation from performing the required indivisible reads and updates. + +If an atomic object is passed as a parameter, then the formal parameter shall either have an atomic type or +allow pass by copy. If an atomic object is used as an actual for a generic formal object of mode in out, +then the type of the generic formal object shall be atomic. If the prefix of an attribute_reference for an +Access attribute denotes an atomic object (including a component), then the designated type of the +resulting access type shall be atomic. If an atomic type is used as an actual for a generic formal derived +type, then the ancestor of the formal type shall be atomic. Corresponding rules apply to volatile objects +and types. + +9.1/3 + +10/3 + +11 + +12/3 + +If a volatile type is used as an actual for a generic formal array type, then the element type of the formal +type shall be volatile. + +12.1/3 + +If an aspect Volatile, Volatile_Components, Atomic, or Atomic_Components is directly specified to have +the value True for a stand-alone constant object, then the aspect Import shall also be specified as True for +it. + +13/3 + +It is illegal to specify the aspect Independent or Independent_Components as True for a component, object +or type if the implementation cannot provide the independent addressability required by the aspect (see +9.10). + +It is illegal to specify a representation aspect for a component, object or type for which the aspect +Independent or Independent_Components is True, in a way that prevents the implementation from +providing the independent addressability required by the aspect. + +Paragraph 14 was moved to Annex J, “Obsolescent Features”. + +Dynamic Semantics + +For an atomic object (including an atomic component) all reads and updates of the object as a whole are +indivisible. + +All tasks of the program (on all processors) that read or update volatile variables see the same order of +updates to the variables. A use of an atomic variable or other mechanism may be necessary to avoid +erroneous execution and to ensure that access to nonatomic volatile variables is sequential (see 9.10). + +Two actions are sequential (see 9.10) if each is the read or update of the same atomic object. + +If a type is atomic or volatile and it is not a by-copy type, then the type is defined to be a by-reference +type. If any subcomponent of a type is atomic or volatile, then the type is defined to be a by-reference +type. + +13.1/3 + +13.2/3 + +15 + +16/3 + +17 + +18 + +619 13 December 2012 + +Shared Variable Control C.6 + + Ada Reference Manual — 2012 Edition + +19 + +20 + +If an actual parameter is atomic or volatile, and the corresponding formal parameter is not, then the +parameter is passed by copy. + +The external effect of a program (see 1.1.3) is defined to include each read and update of a volatile or +atomic object. The implementation shall not generate any memory reads or updates of atomic or volatile +objects other than those specified by the program. + +Implementation Requirements + +21/3 + +If the Pack aspect is True for a type any of whose subcomponents are atomic, the implementation shall not +pack the atomic subcomponents more tightly than that for which it can support indivisible reads and +updates. + +Implementation Advice + +22/2 + +23/2 + +24 + +A load or store of a volatile object whose size is a multiple of System.Storage_Unit and whose alignment +is nonzero, should be implemented by accessing exactly the bits of the object and no others. + +A load or store of an atomic object should, where possible, be implemented by a single load or store +instruction. + +NOTES +9 An imported volatile or atomic constant behaves as a constant (i.e. read-only) with respect to other parts of the Ada +program, but can still be modified by an “external source.” + +C.7 Task Information + +1/3 + +This subclause describes operations and attributes that can be used to obtain the identity of a task. In +addition, a package that associates user-defined information with a task is defined. Finally, a package that +associates termination procedures with a task or set of tasks is defined. + +C.7.1 The Package Task_Identification + +Static Semantics + +1 + +2/2 + +3/3 + +4/3 + +The following language-defined library package exists: +package Ada.Task_Identification is + pragma Preelaborate(Task_Identification); + type Task_Id is private; + pragma Preelaborable_Initialization (Task_Id); + Null_Task_Id : constant Task_Id; + function "=" (Left, Right : Task_Id) return Boolean; + function Image (T : Task_Id) return String; + function Current_Task return Task_Id; + function Environment_Task return Task_Id; + procedure Abort_Task (T : in Task_Id); + function Is_Terminated (T : Task_Id) return Boolean; + function Is_Callable (T : Task_Id) return Boolean; + function Activation_Is_Complete (T : Task_Id) return Boolean; +private + ... -- not specified by the language +end Ada.Task_Identification; + +5 + +A value of the type Task_Id identifies an existent task. The constant Null_Task_Id does not identify any +task. Each object of the type Task_Id is default initialized to the value of Null_Task_Id. + +Dynamic Semantics + +C.6 Shared Variable Control + +13 December 2012 620 + + Ada Reference Manual — 2012 Edition + +The function "=" returns True if and only if Left and Right identify the same task or both have the value +Null_Task_Id. + +The function Image returns an implementation-defined string that identifies T. If T equals Null_Task_Id, +Image returns an empty string. + +The function Current_Task returns a value that identifies the calling task. + +The function Environment_Task returns a value that identifies the environment task. + +The effect of Abort_Task is the same as the abort_statement for the task identified by T. In addition, if T +identifies the environment task, the entire partition is aborted, See E.1. + +The functions Is_Terminated and Is_Callable return the value of the corresponding attribute of the task +identified by T. + +The function Activation_Is_Complete returns True if the task identified by T has completed its activation +(whether successfully or not). It returns False otherwise. If T identifies the environment task, +Activation_Is_Complete returns True after the elaboration of the library_items of the partition has +completed. + +For a prefix T that is of a task type (after any implicit dereference), the following attribute is defined: + +T'Identity + +Yields a value of the type Task_Id that identifies the task denoted by T. + +For a prefix E that denotes an entry_declaration, the following attribute is defined: + +E'Caller + +Yields a value of the type Task_Id that identifies the task whose call is now being serviced. +Use of this attribute is allowed only inside an accept_statement, or entry_body after the +entry_barrier, corresponding to the entry_declaration denoted by E. + +Program_Error is raised if a value of Null_Task_Id is passed as a parameter to Abort_Task, +Is_Terminated, and Is_Callable. + +Abort_Task is a potentially blocking operation (see 9.5.1). + +It is a bounded error to call the Current_Task function from an entry_body, interrupt handler, or +finalization of a task attribute. Program_Error is raised, or an implementation-defined value of the type +Task_Id is returned. + +Bounded (Run-Time) Errors + +If a value of Task_Id is passed as a parameter to any of the operations declared in this package (or any +language-defined child of this package), and the corresponding task object no longer exists, the execution +of the program is erroneous. + +Erroneous Execution + +Documentation Requirements + +The implementation shall document the effect of calling Current_Task from an entry body or interrupt +handler. + +NOTES +10 This package is intended for use in writing user-defined task scheduling packages and constructing server tasks. +Current_Task can be used in conjunction with other operations requiring a task as an argument such as Set_Priority (see +D.5). + +6 + +7 + +8 + +8.1/3 + +9 + +10 + +10.1/3 + +11 + +12 + +13 + +14/3 + +15 + +16 + +17/3 + +18 + +19 + +20 + +11 The function Current_Task and the attribute Caller can return a Task_Id value that identifies the environment task. + +21 + +621 13 December 2012 + +The Package Task_Identification C.7.1 + + Ada Reference Manual — 2012 Edition + +C.7.2 The Package Task_Attributes + +The following language-defined generic library package exists: + +Static Semantics + +with Ada.Task_Identification; use Ada.Task_Identification; +generic + type Attribute is private; + Initial_Value : in Attribute; +package Ada.Task_Attributes is + type Attribute_Handle is access all Attribute; + function Value(T : Task_Id := Current_Task) + return Attribute; + function Reference(T : Task_Id := Current_Task) + return Attribute_Handle; + procedure Set_Value(Val : in Attribute; + T : in Task_Id := Current_Task); + procedure Reinitialize(T : in Task_Id := Current_Task); +end Ada.Task_Attributes; + +Dynamic Semantics + +When an instance of Task_Attributes is elaborated in a given active partition, an object of the actual type +corresponding to the formal type Attribute is implicitly created for each task (of that partition) that exists +and is not yet terminated. This object acts as a user-defined attribute of the task. A task created previously +in the partition and not yet terminated has this attribute from that point on. Each task subsequently created +in the partition will have this attribute when created. In all these cases, the initial value of the given +attribute is Initial_Value. + +The Value operation returns the value of the corresponding attribute of T. + +The Reference operation returns an access value that designates the corresponding attribute of T. + +The Set_Value operation performs any finalization on the old value of the attribute of T and assigns Val to +that attribute (see 5.2 and 7.6). + +The effect of the Reinitialize operation is the same as Set_Value where the Val parameter is replaced with +Initial_Value. + +For all the operations declared in this package, Tasking_Error is raised if the task identified by T is +terminated. Program_Error is raised if the value of T is Null_Task_Id. + +1 + +2 + +3 + +4 + +5 + +6 + +7 + +8 + +9 + +10 + +11 + +12 + +13 + +13.1/2 + +After a task has terminated, all of its attributes are finalized, unless they have been finalized earlier. When +the master of an instantiation of Ada.Task_Attributes is finalized, the corresponding attribute of each task +is finalized, unless it has been finalized earlier. + +Bounded (Run-Time) Errors + +13.2/1 + +If the package Ada.Task_Attributes is instantiated with a controlled type and the controlled type has user- +defined Adjust or Finalize operations that in turn access task attributes by any of the above operations, +then a call of Set_Value of the instantiated package constitutes a bounded error. The call may perform as +expected or may result in forever blocking the calling task and subsequently some or all tasks of the +partition. + +C.7.2 The Package Task_Attributes + +13 December 2012 622 + + Ada Reference Manual — 2012 Edition + +Erroneous Execution + +It is erroneous to dereference the access value returned by a given call on Reference after a subsequent call +on Reinitialize for the same task attribute, or after the associated task terminates. + +If a value of Task_Id is passed as a parameter to any of the operations declared in this package and the +corresponding task object no longer exists, the execution of the program is erroneous. + +14 + +15 + +An access to a task attribute via a value of type Attribute_Handle is erroneous if executed concurrently +with another such access or a call of any of the operations declared in package Task_Attributes. An access +to a task attribute is erroneous if executed concurrently with or after the finalization of the task attribute. + +15.1/2 + +Implementation Requirements + +For a given attribute of a given task, the implementation shall perform the operations declared in this +package atomically with respect to any of these operations of the same attribute of the same task. The +granularity of any locking mechanism necessary to achieve such atomicity is implementation defined. + +16/1 + +After task attributes are finalized, the implementation shall reclaim any storage associated with the +attributes. + +17/2 + +Documentation Requirements + +The implementation shall document the limit on the number of attributes per task, if any, and the limit on +the total storage for attribute values per task, if such a limit exists. + +In addition, if these limits can be configured, the implementation shall document how to configure them. + +Metrics + +The implementation shall document the following metrics: A task calling the following subprograms shall +execute at a sufficiently high priority as to not be preempted during the measurement period. This period +shall start just before issuing the call and end just after the call completes. If the attributes of task T are +accessed by the measurement tests, no other task shall access attributes of that task during the +measurement period. For all measurements described here, the Attribute type shall be a scalar type whose +size is equal to the size of the predefined type Integer. For each measurement, two cases shall be +documented: one where the accessed attributes are of the calling task (that is, the default value for the T +parameter is used), and the other, where T identifies another, nonterminated, task. + +The following calls (to subprograms in the Task_Attributes package) shall be measured: + +• a call to Value, where the return value is Initial_Value; +• a call to Value, where the return value is not equal to Initial_Value; +• a call to Reference, where the return value designates a value equal to Initial_Value; +• a call to Reference, where the return value designates a value not equal to Initial_Value; +• a call to Set_Value where the Val parameter is not equal to Initial_Value and the old attribute + +value is equal to Initial_Value; + +• a call to Set_Value where the Val parameter is not equal to Initial_Value and the old attribute + +value is not equal to Initial_Value. + +An implementation need not actually create the object corresponding to a task attribute until its value is set +to something other than that of Initial_Value, or until Reference is called for the task attribute. Similarly, +when the value of the attribute is to be reinitialized to that of Initial_Value, the object may instead be + +Implementation Permissions + +18 + +19 + +20/2 + +21 + +22 + +23 + +24 + +25 + +26/2 + +27 + +28 + +623 13 December 2012 + +The Package Task_Attributes C.7.2 + + Ada Reference Manual — 2012 Edition + +finalized and its storage reclaimed, to be recreated when needed later. While the object does not exist, the +function Value may simply return Initial_Value, rather than implicitly creating the object. + +29 + +An implementation is allowed to place restrictions on the maximum number of attributes a task may have, +the maximum size of each attribute, and the total storage size allocated for all the attributes of a task. + +Implementation Advice + +30/2 + +Some implementations are targeted to domains in which memory use at run time must be completely +deterministic. For such implementations, it is recommended that the storage for task attributes will be pre- +allocated statically and not from the heap. This can be accomplished by either placing restrictions on the +number and the size of the attributes of a task, or by using the pre-allocated storage for the first N attribute +objects, and the heap for the others. In the latter case, N should be documented. + +30.1/2 + +Finalization of task attributes and reclamation of associated storage should be performed as soon as +possible after task termination. + +31 + +32 + +1/2 + +2/2 + +3/2 + +4/2 + +5/2 + +6/2 + +7/2 + +8/3 + +NOTES +12 An attribute always exists (after instantiation), and has the initial value. It need not occupy memory until the first +operation that potentially changes the attribute value. The same holds true after Reinitialize. + +13 The result of the Reference function should be used with care; it is always safe to use that result in the task body +whose attribute is being accessed. However, when the result is being used by another task, the programmer must make +sure that the task whose attribute is being accessed is not yet terminated. Failing to do so could make the program +execution erroneous. + +C.7.3 The Package Task_Termination + +The following language-defined library package exists: + +Static Semantics + +with Ada.Task_Identification; +with Ada.Exceptions; +package Ada.Task_Termination is + pragma Preelaborate(Task_Termination); + type Cause_Of_Termination is (Normal, Abnormal, Unhandled_Exception); + type Termination_Handler is access protected procedure + (Cause : in Cause_Of_Termination; + T : in Ada.Task_Identification.Task_Id; + X : in Ada.Exceptions.Exception_Occurrence); + procedure Set_Dependents_Fallback_Handler + (Handler: in Termination_Handler); + function Current_Task_Fallback_Handler return Termination_Handler; + procedure Set_Specific_Handler + (T : in Ada.Task_Identification.Task_Id; + Handler : in Termination_Handler); + function Specific_Handler (T : Ada.Task_Identification.Task_Id) + return Termination_Handler; +end Ada.Task_Termination; + +Dynamic Semantics + +The type Termination_Handler identifies a protected procedure to be executed by the implementation +when a task terminates. Such a protected procedure is called a handler. In all cases T identifies the task +that is terminating. If the task terminates due to completing the last statement of its body, or as a result of +waiting on a terminate alternative, and the finalization of the task completes normally, then Cause is set to +Normal and X is set to Null_Occurrence. If the task terminates because it is being aborted, then Cause is + +C.7.2 The Package Task_Attributes + +13 December 2012 624 + + Ada Reference Manual — 2012 Edition + +set to Abnormal; X is set to Null_Occurrence if the finalization of the task completes normally. If the task +terminates because of an exception raised by the execution of its task_body, then Cause is set to +Unhandled_Exception; X is set to the associated exception occurrence if the finalization of the task +completes normally. Independent of how the task completes, if finalization of the task propagates an +exception, then Cause is either Unhandled_Exception or Abnormal, and X is an exception occurrence that +identifies the Program_Error exception. + +Each task has two termination handlers, a fall-back handler and a specific handler. The specific handler +applies only to the task itself, while the fall-back handler applies only to the dependent tasks of the task. A +handler is said to be set if it is associated with a nonnull value of type Termination_Handler, and cleared +otherwise. When a task is created, its specific handler and fall-back handler are cleared. + +The procedure Set_Dependents_Fallback_Handler changes the fall-back handler for the calling task: if +Handler is null, that fall-back handler is cleared; otherwise, it is set to be Handler.all. If a fall-back handler +had previously been set it is replaced. + +The function Current_Task_Fallback_Handler returns the fall-back handler that is currently set for the +calling task, if one is set; otherwise, it returns null. + +The procedure Set_Specific_Handler changes the specific handler for the task identified by T: if Handler +is null, that specific handler is cleared; otherwise, it is set to be Handler.all. If a specific handler had +previously been set it is replaced. + +The function Specific_Handler returns the specific handler that is currently set for the task identified by T, +if one is set; otherwise, it returns null. + +As part of the finalization of a task_body, after performing the actions specified in 7.6 for finalization of a +master, the specific handler for the task, if one is set, is executed. If the specific handler is cleared, a +search for a fall-back handler proceeds by recursively following the master relationship for the task. If a +task is found whose fall-back handler is set, that handler is executed; otherwise, no handler is executed. + +9/2 + +10/3 + +11/3 + +12/3 + +13/3 + +14/2 + +For Set_Specific_Handler or Specific_Handler, Tasking_Error is raised if the task identified by T has +already terminated. Program_Error is raised if the value of T is Ada.Task_Identification.Null_Task_Id. + +15/2 + +An exception propagated from a handler that is invoked as part of the termination of a task has no effect. + +16/2 + +For a call of Set_Specific_Handler or Specific_Handler, if the task identified by T no longer exists, the +execution of the program is erroneous. + +17/2 + +Erroneous Execution + +625 13 December 2012 + +The Package Task_Termination C.7.3 + + Ada Reference Manual — 2012 Edition + +Annex D +(normative) +Real-Time Systems + +This Annex specifies additional characteristics of Ada implementations intended for real-time systems +software. To conform to this Annex, an implementation shall also conform to the Systems Programming +Annex. + +Metrics + +The metrics are documentation requirements; an implementation shall document the values of the +language-defined metrics for at least one configuration of hardware or an underlying system supported by +the implementation, and shall document the details of that configuration. + +The metrics do not necessarily yield a simple number. For some, a range is more suitable, for others a +formula dependent on some parameter is appropriate, and for others, it may be more suitable to break the +metric into several cases. Unless specified otherwise, the metrics in this annex are expressed in processor +clock cycles. For metrics that require documentation of an upper bound, if there is no upper bound, the +implementation shall report that the metric is unbounded. + +NOTES +1 The specification of the metrics makes a distinction between upper bounds and simple execution times. Where +something is just specified as “the execution time of” a piece of code, this leaves one the freedom to choose a +nonpathological case. This kind of metric is of the form “there exists a program such that the value of the metric is V”. +Conversely, the meaning of upper bounds is “there is no program such that the value of the metric is greater than V”. This +kind of metric can only be partially tested, by finding the value of V for one or more test programs. + +2 The metrics do not cover the whole language; they are limited to features that are specified in Annex C, “Systems +Programming” and in this Annex. The metrics are intended to provide guidance to potential users as to whether a +particular implementation of such a feature is going to be adequate for a particular real-time application. As such, the +metrics are aimed at known implementation choices that can result in significant performance differences. + +3 The purpose of the metrics is not necessarily to provide fine-grained quantitative results or to serve as a comparison +between different implementations on the same or different platforms. Instead, their goal is rather qualitative; to define a +standard set of approximate values that can be measured and used to estimate the general suitability of an implementation, +or to evaluate the comparative utility of certain features of an implementation for a particular real-time application. + +1 + +2 + +3 + +4 + +5 + +6 + +D.1 Task Priorities + +This subclause specifies the priority model for real-time systems. In addition, the methods for specifying +priorities are defined. + +1/3 + +Paragraphs 2 through 6 were moved to Annex J, “Obsolescent Features”. + +Static Semantics + +For a task type (including the anonymous type of a single_task_declaration), protected type (including +the anonymous type of a single_protected_declaration), or subprogram, the following language-defined +representation aspects may be specified: + +Priority + +The aspect Priority is an expression, which shall be of type Integer. + +Interrupt_Priority + +The aspect Interrupt_Priority is an expression, which shall be of type Integer. + +6.1/3 + +6.2/3 + +6.3/3 + +627 13 December 2012 + +Real-Time Systems D + + + Ada Reference Manual — 2012 Edition + +This paragraph was deleted. + +Legality Rules + +If the Priority aspect is specified for a subprogram, the expression shall be static, and its value shall be in +the range of System.Priority. + +7/3 + +8/3 + +8.1/3 + +At most one of the Priority and Interrupt_Priority aspects may be specified for a given entity. + +8.2/3 + +Neither of the Priority or Interrupt_Priority aspects shall be specified for a synchronized interface type. + +9 + +10 + +11 + +12 + +The following declarations exist in package System: + +Static Semantics + +subtype Any_Priority is Integer range implementation-defined; +subtype Priority is Any_Priority + range Any_Priority'First .. implementation-defined; +subtype Interrupt_Priority is Any_Priority + range Priority'Last+1 .. Any_Priority'Last; +Default_Priority : constant Priority := (Priority'First + Priority'Last)/2; + +The full range of priority values supported by an implementation is specified by the subtype Any_Priority. +The subrange of priority values that are high enough to require the blocking of one or more interrupts is +specified by the subtype Interrupt_Priority. The subrange of priority values below System.Interrupt_- +Priority'First is specified by the subtype System.Priority. + +13/3 + +This paragraph was deleted. + +Dynamic Semantics + +14/3 + +15 + +16/3 + +17/3 + +18/3 + +19/3 + +The Priority aspect has no effect if it is specified for a subprogram other than the main subprogram; the +Priority value is not associated with any task. + +A task priority is an integer value that indicates a degree of urgency and is the basis for resolving +competing demands of tasks for resources. Unless otherwise specified, whenever tasks compete for +processors or other implementation-defined resources, the resources are allocated to the task with the +highest priority value. The base priority of a task is the priority with which it was created, or to which it +was later set by Dynamic_Priorities.Set_Priority (see D.5). At all times, a task also has an active priority, +which generally reflects its base priority as well as any priority it inherits from other sources. Priority +inheritance is the process by which the priority of a task or other entity (e.g. a protected object; see D.3) is +used in the evaluation of another task's active priority. + +The effect of specifying a Priority or +single_protected_declaration is discussed in D.3. + +Interrupt_Priority aspect + +for a protected + +type or + +The expression specified for the Priority or Interrupt_Priority aspect of a task is evaluated for each task +object (see 9.1). For the Priority aspect, the value of the expression is converted to the subtype Priority; +for the Interrupt_Priority aspect, this value is converted to the subtype Any_Priority. The priority value is +then associated with the task object whose task declaration specifies the aspect. + +Likewise, the priority value is associated with the environment task if the aspect is specified for the main +subprogram. + +The initial value of a task's base priority is specified by default or by means of a Priority or +Interrupt_Priority aspect. After a task is created, its base priority can be changed only by a call to +Dynamic_Priorities.Set_Priority (see D.5). The initial base priority of a task in the absence of an aspect is +the base priority of the task that creates it at the time of creation (see 9.1). If the aspect Priority is not + +D.1 Task Priorities + +13 December 2012 628 + + Ada Reference Manual — 2012 Edition + +for + +the main subprogram, + +specified +is +System.Default_Priority. The task's active priority is used when the task competes for processors. +Similarly, the task's active priority is used to determine the task's position in any queue when +Priority_Queuing is specified (see D.4). + +initial base priority of + +the environment + +task + +the + +At any time, the active priority of a task is the maximum of all the priorities the task is inheriting at that +instant. For a task that is not held (see D.11), its base priority is a source of priority inheritance unless +otherwise specified for a particular task dispatching policy. Other sources of priority inheritance are +specified under the following conditions: + +• During activation, a task being activated inherits the active priority that its activator (see 9.2) + +had at the time the activation was initiated. + +• During rendezvous, the task accepting the entry call inherits the priority of the entry call (see + +9.5.3 and D.4). + +• During a protected action on a protected object, a task inherits the ceiling priority of the + +protected object (see 9.5 and D.3). + +In all of these cases, the priority ceases to be inherited as soon as the condition calling for the inheritance +no longer exists. + +The range of System.Interrupt_Priority shall include at least one value. + +The range of System.Priority shall include at least 30 values. + +Implementation Requirements + +NOTES +4 The priority expression can include references to discriminants of the enclosing type. + +5 It is a consequence of the active priority rules that at the point when a task stops inheriting a priority from another +source, its active priority is re-evaluated. This is in addition to other instances described in this Annex for such re- +evaluation. + +20/2 + +21/1 + +22/1 + +23 + +24 + +25 + +26 + +27 + +28 + +6 An implementation may provide a nonstandard mode in which tasks inherit priorities under conditions other than those +specified above. + +29/3 + +D.2 Priority Scheduling + +This subclause describes the rules that determine which task is selected for execution when more than one +task is ready (see 9). + +1/3 + +D.2.1 The Task Dispatching Model + +The task dispatching model specifies task scheduling, based on conceptual priority-ordered ready queues. + +1/2 + +Static Semantics + +The following language-defined library package exists: + +package Ada.Dispatching is + pragma Preelaborate(Dispatching); + procedure Yield; + Dispatching_Policy_Error : exception; +end Ada.Dispatching; + +1.1/2 + +1.2/3 + +1.3/3 + +1.4/3 + +Dispatching serves as the parent of other language-defined library units concerned with task dispatching. + +1.5/2 + +629 13 December 2012 + +Task Priorities D.1 + + Ada Reference Manual — 2012 Edition + +2/2 + +3 + +4/2 + +5/2 + +6/2 + +7/3 + +8/2 + +9/2 + +10 + +Dynamic Semantics + +A task can become a running task only if it is ready (see 9) and the execution resources required by that +task are available. Processors are allocated to tasks based on each task's active priority. + +It is implementation defined whether, on a multiprocessor, a task that is waiting for access to a protected +object keeps its processor busy. + +Task dispatching is the process by which one ready task is selected for execution on a processor. This +selection is done at certain points during the execution of a task called task dispatching points. A task +reaches a task dispatching point whenever it becomes blocked, and when it terminates. Other task +dispatching points are defined throughout this Annex for specific policies. + +Task dispatching policies are specified in terms of conceptual ready queues and task states. A ready queue +is an ordered list of ready tasks. The first position in a queue is called the head of the queue, and the last +position is called the tail of the queue. A task is ready if it is in a ready queue, or if it is running. Each +processor has one ready queue for each priority value. At any instant, each ready queue of a processor +contains exactly the set of tasks of that priority that are ready for execution on that processor, but are not +running on any processor; that is, those tasks that are ready, are not running on any processor, and can be +executed using that processor and other available resources. A task can be on the ready queues of more +than one processor. + +Each processor also has one running task, which is the task currently being executed by that processor. +Whenever a task running on a processor reaches a task dispatching point it goes back to one or more ready +queues; a task (possibly the same task) is then selected to run on that processor. The task selected is the +one at the head of the highest priority nonempty ready queue; this task is then removed from all ready +queues to which it belongs. + +A call of Yield is a task dispatching point. Yield is a potentially blocking operation (see 9.5.1). + +This paragraph was deleted. + +Implementation Permissions + +An implementation is allowed to define additional resources as execution resources, and to define the +corresponding allocation policies for them. Such resources may have an implementation-defined effect on +task dispatching. + +An implementation may place implementation-defined restrictions on tasks whose active priority is in the +Interrupt_Priority range. + +10.1/2 + +For optimization purposes, an implementation may alter the points at which task dispatching occurs, in an +implementation-defined manner. However, a delay_statement always corresponds to at least one task +dispatching point. + +11/3 + +12 + +13 + +14 + +15 + +NOTES +7 Clause 9 specifies under which circumstances a task becomes ready. The ready state is affected by the rules for task +activation and termination, delay statements, and entry calls. When a task is not ready, it is said to be blocked. + +8 An example of a possible implementation-defined execution resource is a page of physical memory, which needs to be +loaded with a particular page of virtual memory before a task can continue execution. + +9 The ready queues are purely conceptual; there is no requirement that such lists physically exist in an implementation. + +10 While a task is running, it is not on any ready queue. Any time the task that is running on a processor is added to a +ready queue, a new running task is selected for that processor. + +11 In a multiprocessor system, a task can be on the ready queues of more than one processor. At the extreme, if several +processors share the same set of ready tasks, the contents of their ready queues is identical, and so they can be viewed as + +D.2.1 The Task Dispatching Model + +13 December 2012 630 + + Ada Reference Manual — 2012 Edition + +sharing one ready queue, and can be implemented that way. Thus, the dispatching model covers multiprocessors where +dispatching is implemented using a single ready queue, as well as those with separate dispatching domains. + +12 The priority of a task is determined by rules specified in this subclause, and under D.1, “Task Priorities”, D.3, +“Priority Ceiling Locking”, and D.5, “Dynamic Priorities”. + +13 The setting of a task's base priority as a result of a call to Set_Priority does not always take effect immediately when +Set_Priority is called. The effect of setting the task's base priority is deferred while the affected task performs a protected +action. + +16 + +17/2 + +D.2.2 Task Dispatching Pragmas + +This subclause allows a single task dispatching policy to be defined for all priorities, or the range of +priorities to be split into subranges that are assigned individual dispatching policies. + +1/3 + +Syntax + +The form of a pragma Task_Dispatching_Policy is as follows: + pragma Task_Dispatching_Policy(policy_identifier); + +The form of a pragma Priority_Specific_Dispatching is as follows: + pragma Priority_Specific_Dispatching ( + policy_identifier, first_priority_expression, last_priority_expression); + +The expected type for first_priority_expression and last_priority_expression is Integer. + +Name Resolution Rules + +2 + +3 + +3.1/2 + +3.2/2 + +3.3/2 + +The policy_identifier used in a pragma Task_Dispatching_Policy shall be the name of a task dispatching +policy. + +4/2 + +Legality Rules + +The policy_identifier used in a pragma Priority_Specific_Dispatching shall be the name of a task +dispatching policy. + +Both first_priority_expression and last_priority_expression shall be static expressions in the range of +System.Any_Priority; last_priority_expression shall have a value greater than or equal to first_priority_- +expression. + +Pragma Task_Dispatching_Policy specifies the single task dispatching policy. + +Static Semantics + +Pragma Priority_Specific_Dispatching specifies the task dispatching policy for the specified range of +priorities. Tasks with base priorities within +a +Priority_Specific_Dispatching pragma have their active priorities determined according to the specified +dispatching policy. Tasks with active priorities within the range of priorities specified in a +Priority_Specific_Dispatching pragma are dispatched according to the specified dispatching policy. + +range of priorities + +specified + +the + +in + +4.1/2 + +4.2/2 + +4.3/2 + +4.4/2 + +If a partition contains one or more Priority_Specific_Dispatching pragmas, the dispatching policy for +priorities not covered by any Priority_Specific_Dispatching pragmas is FIFO_Within_Priorities. + +4.5/3 + +A Task_Dispatching_Policy pragma is a configuration pragma. A Priority_Specific_Dispatching pragma is +a configuration pragma. + +5/2 + +Post-Compilation Rules + +631 13 December 2012 + +The Task Dispatching Model D.2.1 + + Ada Reference Manual — 2012 Edition + +5.1/2 + +5.2/2 + +The priority ranges specified in more than one Priority_Specific_Dispatching pragma within the same +partition shall not be overlapping. + +If a partition contains one or more Priority_Specific_Dispatching pragmas it shall not contain a +Task_Dispatching_Policy pragma. + +6/2 + +This paragraph was deleted. + +Dynamic Semantics + +7/2 + +7.1/2 + +7.2/3 + +A task dispatching policy specifies the details of task dispatching that are not covered by the basic task +dispatching model. These rules govern when tasks are inserted into and deleted from the ready queues. A +single +is specified by a Task_Dispatching_Policy pragma. Pragma +Priority_Specific_Dispatching assigns distinct dispatching policies to subranges of System.Any_Priority. + +task dispatching policy + +If neither pragma applies to any of the program units comprising a partition, the task dispatching policy +for that partition is unspecified. + +If a partition contains one or more Priority_Specific_Dispatching pragmas, a task dispatching point occurs +for the currently running task of a processor whenever there is a nonempty ready queue for that processor +with a higher priority than the priority of the running task. + +7.3/2 + +A task that has its base priority changed may move from one dispatching policy to another. It is +immediately subject to the new dispatching policy. + +Paragraphs 7 through 13 were moved to D.2.3. + +14.1/2 + +An implementation shall allow, for a single partition, both the locking policy (see D.3) to be specified as +Ceiling_Locking and also one or more Priority_Specific_Dispatching pragmas to be given. + +Implementation Requirements + +Paragraphs 14 through 16 were moved to D.2.3. + +Documentation Requirements + +Implementation Permissions + +18/2 + +19/2 + +Implementations are allowed to define other task dispatching policies, but need not support more than one +task dispatching policy per partition. + +An implementation need not support pragma Priority_Specific_Dispatching if it is infeasible to support it +in the target environment. + +NOTES +Paragraphs 19 through 21 were deleted. + +D.2.3 Preemptive Dispatching + +1/3 + +This subclause defines a preemptive task dispatching policy. + +2/2 + +The policy_identifier FIFO_Within_Priorities is a task dispatching policy. + +Static Semantics + +3/2 + +When FIFO_Within_Priorities is in effect, modifications to the ready queues occur only as follows: + +Dynamic Semantics + +D.2.2 Task Dispatching Pragmas + +13 December 2012 632 + + Ada Reference Manual — 2012 Edition + +• When a blocked task becomes ready, it is added at the tail of the ready queue for its active + +priority. + +• When the active priority of a ready task that is not running changes, or the setting of its base +priority takes effect, the task is removed from the ready queue for its old active priority and is +added at the tail of the ready queue for its new active priority, except in the case where the +active priority is lowered due to the loss of inherited priority, in which case the task is added at +the head of the ready queue for its new active priority. + +• When the setting of the base priority of a running task takes effect, the task is added to the tail of + +the ready queue for its active priority. + +• When a task executes a delay_statement that does not result in blocking, it is added to the tail of + +the ready queue for its active priority. + +Each of the events specified above is a task dispatching point (see D.2.1). + +A task dispatching point occurs for the currently running task of a processor whenever there is a nonempty +ready queue for that processor with a higher priority than the priority of the running task. The currently +running task is said to be preempted and it is added at the head of the ready queue for its active priority. + +4/2 + +5/2 + +6/2 + +7/2 + +8/2 + +9/2 + +An implementation shall allow, for a single partition, both the task dispatching policy to be specified as +FIFO_Within_Priorities and also the locking policy (see D.3) to be specified as Ceiling_Locking. + +10/2 + +Implementation Requirements + +Documentation Requirements + +Priority inversion is the duration for which a task remains at the head of the highest priority nonempty +ready queue while the processor executes a lower priority task. The implementation shall document: + +• The maximum priority inversion a user task can experience due to activity of the implementation + +(on behalf of lower priority tasks), and + +• whether execution of a task can be preempted by the implementation processing of delay + +expirations for lower priority tasks, and if so, for how long. + +NOTES +14 If the active priority of a running task is lowered due to loss of inherited priority (as it is on completion of a protected +operation) and there is a ready task of the same active priority that is not running, the running task continues to run +(provided that there is no higher priority task). + +11/2 + +12/2 + +13/2 + +14/2 + +15 Setting the base priority of a ready task causes the task to move to the tail of the queue for its active priority, +regardless of whether the active priority of the task actually changes. + +15/2 + +D.2.4 Non-Preemptive Dispatching + +This subclause defines a non-preemptive task dispatching policy. + +The policy_identifier Non_Preemptive_FIFO_Within_Priorities is a task dispatching policy. + +Static Semantics + +The following language-defined library package exists: + +package Ada.Dispatching.Non_Preemptive is + pragma Preelaborate(Non_Preemptive); + procedure Yield_To_Higher; + procedure Yield_To_Same_Or_Higher renames Yield; +end Ada.Dispatching.Non_Preemptive; + +1/3 + +2/2 + +2.1/3 + +2.2/3 + +633 13 December 2012 + +Preemptive Dispatching D.2.3 + + Ada Reference Manual — 2012 Edition + +2.3/3 + +A call of Yield_To_Higher is a task dispatching point for this policy. If the task at the head of the highest +priority ready queue has a higher active priority than the calling task, then the calling task is preempted. + +3/2 + +Non_Preemptive_FIFO_Within_Priorities shall not be specified as the policy_identifier of pragma +Priority_Specific_Dispatching (see D.2.2). + +Legality Rules + +Dynamic Semantics + +4/2 + +5/2 + +6/2 + +7/2 + +8/2 + +9/3 + +When Non_Preemptive_FIFO_Within_Priorities is in effect, modifications to the ready queues occur only +as follows: + +• When a blocked task becomes ready, it is added at the tail of the ready queue for its active + +priority. + +• When the active priority of a ready task that is not running changes, or the setting of its base +priority takes effect, the task is removed from the ready queue for its old active priority and is +added at the tail of the ready queue for its new active priority. + +• When the setting of the base priority of a running task takes effect, the task is added to the tail of + +the ready queue for its active priority. + +• When a task executes a delay_statement that does not result in blocking, it is added to the tail of + +the ready queue for its active priority. + +For this policy, blocking or termination of a task, a delay_statement, a call to Yield_To_Higher, and a +call to Yield_To_Same_Or_Higher or Yield are the only task dispatching points (see D.2.1). + +10/2 + +An implementation shall allow, for a single partition, both the task dispatching policy to be specified as +Non_Preemptive_FIFO_Within_Priorities and also the locking policy (see D.3) to be specified as +Ceiling_Locking. + +Implementation Requirements + +Implementation Permissions + +11/3 + +Since implementations are allowed to round all ceiling priorities in subrange System.Priority to +System.Priority'Last (see D.3), an implementation may allow a task of a partition using the +Non_Premptive_FIFO_Within_Priorities policy to execute within a protected object without raising its +active priority provided the associated protected unit does not contain any subprograms with aspects +Interrupt_Handler or Attach_Handler specified, nor does the unit have aspect Interrupt_Priority specified. +When the locking policy (see D.3) is Ceiling_Locking, an implementation taking advantage of this +permission shall ensure that a call to Yield_to_Higher that occurs within a protected action uses the ceiling +priority of the protected object (rather than the active priority of the task) when determining whether to +preempt the task. + +D.2.4 Non-Preemptive Dispatching + +13 December 2012 634 + + Ada Reference Manual — 2012 Edition + +D.2.5 Round Robin Dispatching + +This subclause defines the task dispatching policy Round_Robin_Within_Priorities and the package +Round_Robin. + +1/3 + +The policy_identifier Round_Robin_Within_Priorities is a task dispatching policy. + +Static Semantics + +The following language-defined library package exists: + +with System; +with Ada.Real_Time; +package Ada.Dispatching.Round_Robin is + Default_Quantum : constant Ada.Real_Time.Time_Span := + implementation-defined; + procedure Set_Quantum (Pri : in System.Priority; + Quantum : in Ada.Real_Time.Time_Span); + procedure Set_Quantum (Low, High : in System.Priority; + Quantum : in Ada.Real_Time.Time_Span); + function Actual_Quantum (Pri : System.Priority) + return Ada.Real_Time.Time_Span; + function Is_Round_Robin (Pri : System.Priority) return Boolean; +end Ada.Dispatching.Round_Robin; + +When task dispatching policy Round_Robin_Within_Priorities is the single policy in effect for a partition, +each task with priority in the range of System.Interrupt_Priority is dispatched according to policy +FIFO_Within_Priorities. + +Dynamic Semantics + +The procedures Set_Quantum set the required Quantum value for a single priority level Pri or a range of +priority levels Low .. High. If no quantum is set for a Round Robin priority level, Default_Quantum is +used. + +The function Actual_Quantum returns the actual quantum used by the implementation for the priority level +Pri. + +The function Is_Round_Robin returns True if priority Pri is covered by task dispatching policy +Round_Robin_Within_Priorities; otherwise, it returns False. + +A call of Actual_Quantum or Set_Quantum raises exception Dispatching.Dispatching_Policy_Error if a +predefined policy other than Round_Robin_Within_Priorities applies to the specified priority or any of the +priorities in the specified range. + +For Round_Robin_Within_Priorities, the dispatching rules for FIFO_Within_Priorities apply with the +following additional rules: + +• When a task is added or moved to the tail of the ready queue for its base priority, it has an +execution time budget equal to the quantum for that priority level. This will also occur when a +blocked task becomes executable again. + +• When a task is preempted (by a higher priority task) and is added to the head of the ready queue + +for its priority level, it retains its remaining budget. + +• While a task is executing, its budget is decreased by the amount of execution time it uses. The + +accuracy of this accounting is the same as that for execution time clocks (see D.14). + +2/2 + +3/2 + +4/2 + +5/2 + +6/2 + +7/2 + +8/3 + +9/2 + +10/2 + +11/2 + +12/2 + +13/2 + +635 13 December 2012 + +Round Robin Dispatching D.2.5 + + Ada Reference Manual — 2012 Edition + +14/2 + +• When a task has exhausted its budget and is without an inherited priority (and is not executing +within a protected operation), it is moved to the tail of the ready queue for its priority level. This +is a task dispatching point. + +15/2 + +An implementation shall allow, for a single partition, both the task dispatching policy to be specified as +Round_Robin_Within_Priorities and also the locking policy (see D.3) to be specified as Ceiling_Locking. + +Implementation Requirements + +16/2 + +An implementation shall document the quantum values supported. + +Documentation Requirements + +17/2 + +An implementation shall document the accuracy with which it detects the exhaustion of the budget of a +task. + +18/2 + +19/2 + +1/2 + +2/3 + +7/2 + +8/2 + +9/2 + +NOTES +16 Due to implementation constraints, the quantum value returned by Actual_Quantum might not be identical to that set +with Set_Quantum. + +17 A task that executes continuously with an inherited priority will not be subject to round robin dispatching. + +D.2.6 Earliest Deadline First Dispatching + +The deadline of a task is an indication of the urgency of the task; it represents a point on an ideal physical +time line. The deadline might affect how resources are allocated to the task. + +This subclause defines a package for representing the deadline of a task and a dispatching policy that +defines Earliest Deadline First (EDF) dispatching. An aspect is defined to assign an initial deadline to a +task. + +Paragraphs 3 through 6 were moved to Annex J, “Obsolescent Features”. + +The policy_identifier EDF_Across_Priorities is a task dispatching policy. + +The following language-defined library package exists: + +Static Semantics + +with Ada.Real_Time; +with Ada.Task_Identification; +package Ada.Dispatching.EDF is + subtype Deadline is Ada.Real_Time.Time; + Default_Deadline : constant Deadline := + Ada.Real_Time.Time_Last; + procedure Set_Deadline (D : in Deadline; + T : in Ada.Task_Identification.Task_Id := + Ada.Task_Identification.Current_Task); + procedure Delay_Until_And_Set_Deadline ( + Delay_Until_Time : in Ada.Real_Time.Time; + Deadline_Offset : in Ada.Real_Time.Time_Span); + function Get_Deadline (T : Ada.Task_Identification.Task_Id := + Ada.Task_Identification.Current_Task) return Deadline; +end Ada.Dispatching.EDF; + +9.1/3 + +For a task type (including the anonymous type of a single_task_declaration) or subprogram, the following +language-defined representation aspect may be specified: + +9.2/3 + +Relative_Deadline + +The aspect Relative_Deadline +Real_Time.Time_Span. + +is an expression, which + +shall be of + +type + +D.2.5 Round Robin Dispatching + +13 December 2012 636 + + + Ada Reference Manual — 2012 Edition + +The Relative_Deadline aspect shall not be specified on a task interface type. + +Legality Rules + +Post-Compilation Rules + +If the EDF_Across_Priorities policy is specified for a partition, then the Ceiling_Locking policy (see D.3) +shall also be specified for the partition. + +If the EDF_Across_Priorities policy appears in a Priority_Specific_Dispatching pragma (see D.2.2) in a +partition, then the Ceiling_Locking policy (see D.3) shall also be specified for the partition. + +Dynamic Semantics + +The Relative_Deadline aspect has no effect if it is specified for a subprogram other than the main +subprogram. + +The initial absolute deadline of a task for which aspect Relative_Deadline is specified is the value of +Real_Time.Clock + the expression that is the value of the aspect, where this entire expression, including +the call of Real_Time.Clock, is evaluated between task creation and the start of its activation. If the aspect +Relative_Deadline is not specified, then the initial absolute deadline of a task is the value of +Default_Deadline. The environment task is also given an initial deadline by this rule, using the value of +the Relative_Deadline aspect of the main subprogram (if any). + +The procedure Set_Deadline changes the absolute deadline of the task to D. The function Get_Deadline +returns the absolute deadline of the task. + +The procedure Delay_Until_And_Set_Deadline delays the calling task until time Delay_Until_Time. +When the task becomes runnable again it will have deadline Delay_Until_Time + Deadline_Offset. + +On a system with a single processor, the setting of the deadline of a task to the new value occurs +immediately at the first point that is outside the execution of a protected action. If the task is currently on a +ready queue it is removed and re-entered on to the ready queue determined by the rules defined below. + +When EDF_Across_Priorities is specified for priority range Low..High all ready queues in this range are +ordered by deadline. The task at the head of a queue is the one with the earliest deadline. + +A task dispatching point occurs for the currently running task T to which policy EDF_Across_Priorities +applies: + +• when a change to the deadline of T occurs; +• + +there is a task on the ready queue for the active priority of T with a deadline earlier than the +deadline of T; or + +• + +there is a nonempty ready queue for that processor with a higher priority than the active priority +of the running task. + +In these cases, the currently running task is said to be preempted and is returned to the ready queue for its +active priority. + +For a task T to which policy EDF_Across_Priorities applies, the base priority is not a source of priority +inheritance; the active priority when first activated or while it is blocked is defined as the maximum of the +following: + +• + +• + +the lowest priority in the range specified as EDF_Across_Priorities that includes the base +priority of T; + +the priorities, if any, currently inherited by T; + +9.3/3 + +10/2 + +11/2 + +12/3 + +13/3 + +14/2 + +15/2 + +16/2 + +17/2 + +18/2 + +19/2 + +20/2 + +21/2 + +22/2 + +23/2 + +24/2 + +25/2 + +637 13 December 2012 + +Earliest Deadline First Dispatching D.2.6 + + Ada Reference Manual — 2012 Edition + +26/3 + +• + +the highest priority P, if any, less than the base priority of T such that one or more tasks are +executing within a protected object with ceiling priority P and task T has an earlier deadline than +all such tasks; and furthermore T has an earlier deadline than all other tasks on ready queues +with priorities in the given EDF_Across_Priorities range that are strictly less than P. + +27/2 + +28/2 + +When a task T is first activated or becomes unblocked, it is added to the ready queue corresponding to this +active priority. Until it becomes blocked again, the active priority of T remains no less than this value; it +will exceed this value only while it is inheriting a higher priority. + +When the setting of the base priority of a ready task takes effect and the new priority is in a range +specified as EDF_Across_Priorities, the task is added to the ready queue corresponding to its new active +priority, as determined above. + +29/2 + +For all the operations defined in Dispatching.EDF, Tasking_Error is raised if the task identified by T has +terminated. Program_Error is raised if the value of T is Null_Task_Id. + +30/2 + +If EDF_Across_Priorities is specified for priority range Low..High, it is a bounded error to declare a +protected object with ceiling priority Low or to assign the value Low to attribute 'Priority. In either case +either Program_Error is raised or the ceiling of the protected object is assigned the value Low+1. + +Bounded (Run-Time) Errors + +31/2 + +If a value of Task_Id is passed as a parameter to any of the subprograms of this package and the +corresponding task object no longer exists, the execution of the program is erroneous. + +Erroneous Execution + +Documentation Requirements + +32/2 + +On a multiprocessor, the implementation shall document any conditions that cause the completion of the +setting of the deadline of a task to be delayed later than what is specified for a single processor. + +33/3 + +34/2 + +NOTES +18 If two adjacent priority ranges, A..B and B+1..C are specified to have policy EDF_Across_Priorities, then this is not +equivalent to this policy being specified for the single range, A..C. + +19 The above rules implement the preemption-level protocol (also called Stack Resource Policy protocol) for resource +sharing under EDF dispatching. The preemption-level for a task is denoted by its base priority. The definition of a ceiling +preemption-level for a protected object follows the existing rules for ceiling locking. + +D.3 Priority Ceiling Locking + +1/3 + +This subclause specifies the interactions between priority task scheduling and protected object ceilings. +This interaction is based on the concept of the ceiling priority of a protected object. + +The form of a pragma Locking_Policy is as follows: + pragma Locking_Policy(policy_identifier); + +Syntax + +Legality Rules + +The policy_identifier shall either be Ceiling_Locking or an implementation-defined identifier. + +A Locking_Policy pragma is a configuration pragma. + +Post-Compilation Rules + +2 + +3 + +4 + +5 + +D.2.6 Earliest Deadline First Dispatching + +13 December 2012 638 + + Ada Reference Manual — 2012 Edition + +Dynamic Semantics + +A locking policy specifies the details of protected object locking. All protected objects have a priority. The +locking policy specifies the meaning of the priority of a protected object, and the relationships between +these priorities and task priorities. In addition, the policy specifies the state of a task when it executes a +protected action, and how its active priority is affected by the locking. The locking policy is specified by a +Locking_Policy pragma. For implementation-defined locking policies, the meaning of the priority of a +protected object is implementation defined. If no Locking_Policy pragma applies to any of the program +units comprising a partition, the locking policy for that partition, as well as the meaning of the priority of a +protected object, are implementation defined. + +6/2 + +The expression specified for the Priority or Interrupt_Priority aspect (see D.1) is evaluated as part of the +creation of the corresponding protected object and converted to the subtype System.Any_Priority or +System.Interrupt_Priority, respectively. The value of the expression is the initial priority of the +corresponding protected object. If no Priority or Interrupt_Priority aspect is specified for a protected +object, the initial priority is specified by the locking policy. + +6.1/3 + +There is one predefined locking policy, Ceiling_Locking; this policy is defined as follows: + +• Every protected object has a ceiling priority, which is determined by either a Priority or +Interrupt_Priority aspect as defined in D.1, or by assignment to the Priority attribute as described +in D.5.2. The ceiling priority of a protected object (or ceiling, for short) is an upper bound on the +active priority a task can have when it calls protected operations of that protected object. +• The initial ceiling priority of a protected object is equal to the initial priority for that object. +• If an Interrupt_Handler or Attach_Handler aspect (see C.3.1) is specified for a protected +subprogram of a protected type that does not have the Interrupt_Priority aspect specified, the +initial priority of protected objects of that type is implementation defined, but in the range of the +subtype System.Interrupt_Priority. + +• If neither aspect Priority nor Interrupt_Priority is specified for a protected type, and no protected +subprogram of the type has aspect Interrupt_Handler or Attach_Handler specified, then the +initial priority of the corresponding protected object is System.Priority'Last. + +• While a task executes a protected action, it inherits the ceiling priority of the corresponding + +protected object. + +• When a task calls a protected operation, a check is made that its active priority is not higher than +the ceiling of the corresponding protected object; Program_Error is raised if this check fails. + +Bounded (Run-Time) Errors + +Following any change of priority, it is a bounded error for the active priority of any task with a call queued +on an entry of a protected object to be higher than the ceiling priority of the protected object. In this case +one of the following applies: + +• at any time prior to executing the entry body Program_Error is raised in the calling task; +• when the entry is open the entry body is executed at the ceiling priority of the protected object; +• when the entry is open the entry body is executed at the ceiling priority of the protected object + +and then Program_Error is raised in the calling task; or + +• when the entry is open the entry body is executed at the ceiling priority of the protected object + +that was in effect when the entry call was queued. + +7 + +8/3 + +9/2 + +10/3 + +11/3 + +12 + +13 + +13.1/2 + +13.2/2 + +13.3/2 + +13.4/2 + +13.5/2 + +639 13 December 2012 + +Priority Ceiling Locking D.3 + + Ada Reference Manual — 2012 Edition + +14 + +15/2 + +16 + +17 + +18 + +19 + +20 + +21 + +22 + +23 + +Implementation Permissions + +The implementation is allowed to round all ceilings in a certain subrange of System.Priority or +System.Interrupt_Priority up to the top of that subrange, uniformly. + +Implementations are allowed to define other locking policies, but need not support more than one locking +policy per partition. + +Since implementations are allowed to place restrictions on code that runs at an interrupt-level active +priority (see C.3.1 and D.2.1), the implementation may implement a language feature in terms of a +protected object with an implementation-defined ceiling, but the ceiling shall be no less than Priority'Last. + +The implementation should use names that end with “_Locking” for implementation-defined locking +policies. + +Implementation Advice + +NOTES +20 While a task executes in a protected action, it can be preempted only by tasks whose active priorities are higher than +the ceiling priority of the protected object. + +21 If a protected object has a ceiling priority in the range of Interrupt_Priority, certain interrupts are blocked while +protected actions of that object execute. In the extreme, if the ceiling is Interrupt_Priority'Last, all blockable interrupts are +blocked during that time. + +22 The ceiling priority of a protected object has to be in the Interrupt_Priority range if one of its procedures is to be used +as an interrupt handler (see C.3). + +23 When specifying the ceiling of a protected object, one should choose a value that is at least as high as the highest +active priority at which tasks can be executing when they call protected operations of that object. In determining this value +the following factors, which can affect active priority, should be considered: the effect of Set_Priority, nested protected +operations, entry calls, task activation, and other implementation-defined factors. + +24 Attaching a protected procedure whose ceiling is below the interrupt hardware priority to an interrupt causes the +execution of the program to be erroneous (see C.3.1). + +25 On a single processor implementation, the ceiling priority rules guarantee that there is no possibility of deadlock +involving only protected subprograms (excluding the case where a protected operation calls another protected operation +on the same protected object). + +D.4 Entry Queuing Policies + +1/3 + +This subclause specifies a mechanism for a user to choose an entry queuing policy. It also defines two such +policies. Other policies are implementation defined. + +2 + +3 + +4 + +The form of a pragma Queuing_Policy is as follows: + pragma Queuing_Policy(policy_identifier); + +Syntax + +Legality Rules + +The policy_identifier shall be either FIFO_Queuing, Priority_Queuing or an implementation-defined +identifier. + +5 + +A Queuing_Policy pragma is a configuration pragma. + +Post-Compilation Rules + +D.3 Priority Ceiling Locking + +13 December 2012 640 + + Ada Reference Manual — 2012 Edition + +Dynamic Semantics + +A queuing policy governs the order in which tasks are queued for entry service, and the order in which +different entry queues are considered for service. The queuing policy is specified by a Queuing_Policy +pragma. + +Two queuing policies, FIFO_Queuing and Priority_Queuing, are language defined. If no Queuing_Policy +pragma applies to any of the program units comprising the partition, the queuing policy for that partition is +FIFO_Queuing. The rules for this policy are specified in 9.5.3 and 9.7.1. + +The Priority_Queuing policy is defined as follows: + +• The calls to an entry (including a member of an entry family) are queued in an order consistent +with the priorities of the calls. The priority of an entry call is initialized from the active priority +of the calling task at the time the call is made, but can change later. Within the same priority, the +order is consistent with the calling (or requeuing, or priority setting) time (that is, a FIFO order). +• After a call is first queued, changes to the active priority of a task do not affect the priority of the + +call, unless the base priority of the task is set while the task is blocked on an entry call. + +• When the base priority of a task is set (see D.5), if the task is blocked on an entry call, and the +call is queued, the priority of the call is updated to the new active priority of the calling task. +This causes the call to be removed from and then reinserted in the queue at the new active +priority. + +• When more than one condition of an entry_barrier of a protected object becomes True, and more +than one of the respective queues is nonempty, the call with the highest priority is selected. If +more than one such call has the same priority, the call that is queued on the entry whose +declaration is first in textual order in the protected_definition is selected. For members of the +same entry family, the one with the lower family index is selected. + +• If the expiration time of two or more open delay_alternatives is the same and no other +accept_alternatives are open, the sequence_of_statements of the delay_alternative that is first +in textual order in the selective_accept is executed. + +• When more than one alternative of a selective_accept is open and has queued calls, an +alternative whose queue has the highest-priority call at its head is selected. If two or more open +alternatives have equal-priority queued calls, then a call on the entry in the accept_alternative +that is first in textual order in the selective_accept is selected. + +6 + +7/2 + +8 + +9 + +10/1 + +11 + +12 + +13 + +14 + +Implementation Permissions + +Implementations are allowed to define other queuing policies, but need not support more than one queuing +policy per partition. + +15/2 + +Implementations are allowed to defer the reordering of entry queues following a change of base priority of +a task blocked on the entry call if it is not practical to reorder the queue immediately. + +15.1/2 + +The implementation should use names that end with “_Queuing” for implementation-defined queuing +policies. + +16 + +Implementation Advice + +641 13 December 2012 + +Entry Queuing Policies D.4 + + Ada Reference Manual — 2012 Edition + +D.5 Dynamic Priorities + +1/3 + +This subclause describes how the priority of an entity can be modified or queried at run time. + +D.5.1 Dynamic Priorities for Tasks + +1/3 + +This subclause describes how the base priority of a task can be modified or queried at run time. + +The following language-defined library package exists: + +Static Semantics + +with System; +with Ada.Task_Identification; -- See C.7.1 +package Ada.Dynamic_Priorities is + pragma Preelaborate(Dynamic_Priorities); + procedure Set_Priority(Priority : in System.Any_Priority; + T : in Ada.Task_Identification.Task_Id := + Ada.Task_Identification.Current_Task); + function Get_Priority (T : Ada.Task_Identification.Task_Id := + Ada.Task_Identification.Current_Task) + return System.Any_Priority; +end Ada.Dynamic_Priorities; + +Dynamic Semantics + +The procedure Set_Priority sets the base priority of the specified task to the specified Priority value. +Set_Priority has no effect if the task is terminated. + +The function Get_Priority returns T's current base priority. Tasking_Error is raised if the task is +terminated. + +Program_Error is raised by Set_Priority and Get_Priority if T is equal to Null_Task_Id. + +2 + +3/2 + +4 + +5 + +6 + +7 + +8 + +9 + +10/2 + +On a system with a single processor, the setting of the base priority of a task T to the new value occurs +immediately at the first point when T is outside the execution of a protected action. + +Paragraph 11 was deleted. + +12 + +If any subprogram in this package is called with a parameter T that specifies a task object that no longer +exists, the execution of the program is erroneous. + +Erroneous Execution + +12.1/2 + +On a multiprocessor, the implementation shall document any conditions that cause the completion of the +setting of the priority of a task to be delayed later than what is specified for a single processor. + +Documentation Requirements + +13 + +14 + +The implementation shall document the following metric: + +Metrics + +• The execution time of a call to Set_Priority, for the nonpreempting case, in processor clock +cycles. This is measured for a call that modifies the priority of a ready task that is not running +(which cannot be the calling one), where the new base priority of the affected task is lower than +the active priority of the calling task, and the affected task is not on any entry queue and is not +executing a protected operation. + +D.5 Dynamic Priorities + +13 December 2012 642 + + Ada Reference Manual — 2012 Edition + +NOTES +26 Setting a task's base priority affects task dispatching. First, it can change the task's active priority. Second, under the +FIFO_Within_Priorities policy it always causes the task to move to the tail of the ready queue corresponding to its active +priority, even if the new base priority is unchanged. + +27 Under the priority queuing policy, setting a task's base priority has an effect on a queued entry call if the task is +blocked waiting for the call. That is, setting the base priority of a task causes the priority of a queued entry call from that +task to be updated and the call to be removed and then reinserted in the entry queue at the new priority (see D.4), unless +the call originated from the triggering_statement of an asynchronous_select. + +28 The effect of two or more Set_Priority calls executed in parallel on the same task is defined as executing these calls in +some serial order. + +29 The rule for when Tasking_Error is raised for Set_Priority or Get_Priority is different from the rule for when +Tasking_Error is raised on an entry call (see 9.5.3). In particular, querying the priority of a completed or an abnormal task +is allowed, so long as the task is not yet terminated, and setting the priority of a task is allowed for any task state +(including for terminated tasks). + +15/2 + +16 + +17 + +18/3 + +30 Changing the priorities of a set of tasks can be performed by a series of calls to Set_Priority for each task separately. +For this to work reliably, it should be done within a protected operation that has high enough ceiling priority to guarantee +that the operation completes without being preempted by any of the affected tasks. + +19 + +D.5.2 Dynamic Priorities for Protected Objects + +This subclause specifies how the priority of a protected object can be modified or queried at run time. + +Static Semantics + +The following attribute is defined for a prefix P that denotes a protected object: + +P'Priority + +Denotes a non-aliased component of the protected object P. This component is of type +System.Any_Priority and its value is the priority of P. P'Priority denotes a variable if and +only if P denotes a variable. A reference to this attribute shall appear only within the body +of P. + +1/3 + +2/2 + +3/2 + +The initial value of this attribute is the initial value of the priority of the protected object, and can be +changed by an assignment. + +4/2 + +Dynamic Semantics + +If the locking policy Ceiling_Locking (see D.3) is in effect, then the ceiling priority of a protected object P +is set to the value of P'Priority at the end of each protected action of P. + +If the locking policy Ceiling_Locking is in effect, then for a protected object P with either an +Attach_Handler or Interrupt_Handler aspect specified for one of its procedures, a check is made that the +value to be assigned to P'Priority is in the range System.Interrupt_Priority. If the check fails, +Program_Error is raised. + +The implementation shall document the following metric: + +Metrics + +• The difference in execution time of calls to the following procedures in protected object P: + +protected P is + procedure Do_Not_Set_Ceiling (Pr : System.Any_Priority); + procedure Set_Ceiling (Pr : System.Any_Priority); +end P; + +5/3 + +6/3 + +7/2 + +8/2 + +9/2 + +643 13 December 2012 + +Dynamic Priorities for Tasks D.5.1 + + Ada Reference Manual — 2012 Edition + +10/2 + +11/2 + +protected body P is + procedure Do_Not_Set_Ceiling (Pr : System.Any_Priority) is + begin + null; + end; + procedure Set_Ceiling (Pr : System.Any_Priority) is + begin + P'Priority := Pr; + end; +end P; + +NOTES +31 Since P'Priority is a normal variable, the value following an assignment to the attribute immediately reflects the new +value even though its impact on the ceiling priority of P is postponed until completion of the protected action in which it +is executed. + +D.6 Preemptive Abort + +1/3 + +This subclause specifies requirements on the immediacy with which an aborted construct is completed. + +2 + +3 + +4 + +5 + +6 + +7/2 + +8 + +9 + +On a system with a single processor, an aborted construct is completed immediately at the first point that +is outside the execution of an abort-deferred operation. + +Dynamic Semantics + +On a multiprocessor, the implementation shall document any conditions that cause the completion of an +aborted construct to be delayed later than what is specified for a single processor. + +Documentation Requirements + +The implementation shall document the following metrics: + +Metrics + +• The execution time, in processor clock cycles, that it takes for an abort_statement to cause the +completion of the aborted task. This is measured in a situation where a task T2 preempts task T1 +and aborts T1. T1 does not have any finalization code. T2 shall verify that T1 has terminated, by +means of the Terminated attribute. + +• On a multiprocessor, an upper bound in seconds, on the time that the completion of an aborted + +task can be delayed beyond the point that it is required for a single processor. + +• An upper bound on the execution time of an asynchronous_select, in processor clock cycles. +This is measured between a point immediately before a task T1 executes a protected operation +Pr.Set that makes the condition of an entry_barrier Pr.Wait True, and the point where task T2 +resumes execution immediately after an entry call to Pr.Wait in an asynchronous_select. T1 +preempts T2 while T2 is executing the abortable part, and then blocks itself so that T2 can +execute. The execution time of T1 is measured separately, and subtracted. + +• An upper bound on the execution time of an asynchronous_select, in the case that no +asynchronous transfer of control takes place. This is measured between a point immediately +before a task executes the asynchronous_select with a nonnull abortable part, and the point +where the task continues execution immediately after it. The execution time of the abortable part +is subtracted. + +Even though the abort_statement is included in the list of potentially blocking operations (see 9.5.1), it is +recommended that this statement be implemented in a way that never requires the task executing the +abort_statement to block. + +Implementation Advice + +D.5.2 Dynamic Priorities for Protected Objects + +13 December 2012 644 + + Ada Reference Manual — 2012 Edition + +On a multi-processor, the delay associated with aborting a task on another processor should be bounded; +the implementation should use periodic polling, if necessary, to achieve this. + +NOTES +32 Abortion does not change the active or base priority of the aborted task. + +33 Abortion cannot be more immediate than is allowed by the rules for deferral of abortion during finalization and in +protected actions. + +10 + +11 + +12 + +D.7 Tasking Restrictions + +This subclause defines restrictions that can be used with a pragma Restrictions (see 13.12) to facilitate the +construction of highly efficient tasking run-time systems. + +1/3 + +The following restriction_identifiers are language defined: + +Static Semantics + +No_Task_Hierarchy + +No task depends on a master other than the library-level master. + +No_Nested_Finalization + +Objects of a type that needs finalization (see 7.6) are declared only at library level. If an +access type does not have library-level accessibility, then there are no allocators of the type +where +the subtype_indication or +qualified_expression needs finalization. + +the subtype_mark of + +type determined by + +the + +No_Abort_Statements + +There are no abort_statements, and +Task_Identification.Abort_Task. + +there + +is no use of a name denoting + +No_Terminate_Alternatives + +There are no selective_accepts with terminate_alternatives. + +No_Task_Allocators + +There are no allocators for task types or types containing task subcomponents. + +In the case of an initialized allocator of an access type whose designated type is class-wide +and limited, a check is made that the specific type of the allocated object has no task +subcomponents. Program_Error is raised if this check fails. + +No_Implicit_Heap_Allocations + +There are no operations that implicitly require heap storage allocation to be performed by +the implementation. The operations that implicitly require heap storage allocation are +implementation defined. + +No_Dynamic_Priorities + +There are no semantic dependences on the package Dynamic_Priorities, and no occurrences +of the attribute Priority. + +No_Dynamic_Attachment + +There is no use of a name denoting any of the operations defined in package Interrupts +(Is_Reserved, +Is_Attached, Current_Handler, Attach_Handler, Exchange_Handler, +Detach_Handler, and Reference). + +No_Local_Protected_Objects + +Protected objects are declared only at library level. + +No_Local_Timing_Events + +Timing_Events are declared only at library level. + +645 13 December 2012 + +Preemptive Abort D.6 + +2 + +3/3 + +4/3 + +5/3 + +6 + +7 + +7.1/3 + +8 + +9/2 + +10/3 + +10.1/3 + +10.2/3 + + + + + + + + + + + + + Ada Reference Manual — 2012 Edition + +10.3/2 + +No_Protected_Type_Allocators + +10.4/3 + +There are no allocators for protected types or types containing protected type +subcomponents. + +In the case of an initialized allocator of an access type whose designated type is class-wide +and limited, a check is made that the specific type of the allocated object has no protected +subcomponents. Program_Error is raised if this check fails. + +10.5/3 + +No_Relative_Delay + +There are no delay_relative_statements, and there is no use of a name that denotes the +Timing_Events.Set_Handler subprogram that has a Time_Span parameter. + +10.6/3 + +No_Requeue_Statements + +There are no requeue_statements. + +10.7/3 + +No_Select_Statements + +There are no select_statements. + +10.8/3 + +No_Specific_Termination_Handlers + +There is no use of a name denoting the Set_Specific_Handler and Specific_Handler +subprograms in Task_Termination. + +10.9/3 + +Simple_Barriers + +The Boolean expression in each entry barrier is either a static expression or a name that +statically denotes a component of the enclosing protected object. + +11 + +12 + +The following restriction_parameter_identifiers are language defined: + +Max_Select_Alternatives + +Specifies the maximum number of alternatives in a selective_accept. + +13 + +Max_Task_Entries + +Specifies the maximum number of entries per task. The bounds of every entry family of a +task unit shall be static, or shall be defined by a discriminant of a subtype whose +corresponding bound is static. A value of zero indicates that no rendezvous are possible. + +14 + +Max_Protected_Entries + +Specifies the maximum number of entries per protected type. The bounds of every entry +family of a protected unit shall be static, or shall be defined by a discriminant of a subtype +whose corresponding bound is static. + +15/2 + +The following restriction_identifier is language defined: + +15.1/2 + +No_Task_Termination + +Dynamic Semantics + +All tasks are nonterminating. It is implementation-defined what happens if a task attempts +to terminate. If there is a fall-back handler (see C.7.3) set for the partition it should be +called when the first task attempts to terminate. + +16 + +The following restriction_parameter_identifiers are language defined: + +17/1 + +Max_Storage_At_Blocking + +Specifies the maximum portion (in storage elements) of a task's Storage_Size that can be +retained by a blocked task. If an implementation chooses to detect a violation of this +restriction, Storage_Error should be raised; otherwise, the behavior is implementation +defined. + +18/1 + +Max_Asynchronous_Select_Nesting + +Specifies the maximum dynamic nesting level of asynchronous_selects. A value of zero +prevents +if a program contains an + +the use of any asynchronous_select and, + +D.7 Tasking Restrictions + +13 December 2012 646 + + + + + + + + + + + + + + + Ada Reference Manual — 2012 Edition + +asynchronous_select, it is illegal. If an implementation chooses to detect a violation of this +restriction for values other than zero, Storage_Error should be raised; otherwise, the +behavior is implementation defined. + +Max_Tasks Specifies the maximum number of task creations that may be executed over the lifetime of +a partition, not counting the creation of the environment task. A value of zero prevents any +task creation and, if a program contains a task creation, it is illegal. If an implementation +chooses to detect a violation of this restriction, Storage_Error should be raised; otherwise, +the behavior is implementation defined. + +Max_Entry_Queue_Length + +Max_Entry_Queue_Length defines the maximum number of calls that are queued on an +entry. Violation of this restriction results in the raising of Program_Error at the point of the +call or requeue. + +No_Standard_Allocators_After_Elaboration + +19/1 + +19.1/2 + +19.2/3 + +Specifies that an allocator using a standard storage pool (see 13.11) shall not occur within a +parameterless library subprogram, nor within the handled_sequence_of_statements of a +task body. For the purposes of this rule, an allocator of a type derived from a formal access +type does not use a standard storage pool. + +At run time, Storage_Error is raised if an allocator using a standard storage pool is +evaluated after the elaboration of the library_items of the partition has completed. + +19.3/3 + +It is implementation defined whether the use of pragma Restrictions results in a reduction in executable +program size, storage requirements, or execution time. If possible, the implementation should provide +quantitative descriptions of such effects for each restriction. + +When feasible, the implementation should take advantage of the specified restrictions to produce a more +efficient implementation. + +Implementation Advice + +NOTES +34 The above Storage_Checks can be suppressed with pragma Suppress. + +D.8 Monotonic Time + +This subclause specifies a high-resolution, monotonic clock package. + +The following language-defined library package exists: + +Static Semantics + +package Ada.Real_Time is + type Time is private; + Time_First : constant Time; + Time_Last : constant Time; + Time_Unit : constant := implementation-defined-real-number; + type Time_Span is private; + Time_Span_First : constant Time_Span; + Time_Span_Last : constant Time_Span; + Time_Span_Zero : constant Time_Span; + Time_Span_Unit : constant Time_Span; + Tick : constant Time_Span; + function Clock return Time; + +20 + +21 + +22 + +1/3 + +2 + +3 + +4 + +5 + +6 + +647 13 December 2012 + +Tasking Restrictions D.7 + + + + + Ada Reference Manual — 2012 Edition + +7 + +8 + +9 + +10 + +11/1 + +12 + +13 + +14/2 + +15 + +16 + +17 + +18 + +19 + +20 + +21 + + function "+" (Left : Time; Right : Time_Span) return Time; + function "+" (Left : Time_Span; Right : Time) return Time; + function "-" (Left : Time; Right : Time_Span) return Time; + function "-" (Left : Time; Right : Time) return Time_Span; + function "<" (Left, Right : Time) return Boolean; + function "<="(Left, Right : Time) return Boolean; + function ">" (Left, Right : Time) return Boolean; + function ">="(Left, Right : Time) return Boolean; + function "+" (Left, Right : Time_Span) return Time_Span; + function "-" (Left, Right : Time_Span) return Time_Span; + function "-" (Right : Time_Span) return Time_Span; + function "*" (Left : Time_Span; Right : Integer) return Time_Span; + function "*" (Left : Integer; Right : Time_Span) return Time_Span; + function "/" (Left, Right : Time_Span) return Integer; + function "/" (Left : Time_Span; Right : Integer) return Time_Span; + function "abs"(Right : Time_Span) return Time_Span; +This paragraph was deleted. + function "<" (Left, Right : Time_Span) return Boolean; + function "<="(Left, Right : Time_Span) return Boolean; + function ">" (Left, Right : Time_Span) return Boolean; + function ">="(Left, Right : Time_Span) return Boolean; + function To_Duration (TS : Time_Span) return Duration; + function To_Time_Span (D : Duration) return Time_Span; + function Nanoseconds (NS : Integer) return Time_Span; + function Microseconds (US : Integer) return Time_Span; + function Milliseconds (MS : Integer) return Time_Span; + function Seconds (S : Integer) return Time_Span; + function Minutes (M : Integer) return Time_Span; + type Seconds_Count is range implementation-defined; + procedure Split(T : in Time; SC : out Seconds_Count; TS : out Time_Span); + function Time_Of(SC : Seconds_Count; TS : Time_Span) return Time; +private + ... -- not specified by the language +end Ada.Real_Time; + +In this Annex, real time is defined to be the physical time as observed in the external environment. The +type Time is a time type as defined by 9.6; values of this type may be used in a delay_until_statement. +Values of this type represent segments of an ideal time line. The set of values of the type Time +corresponds one-to-one with an implementation-defined range of mathematical integers. + +The Time value I represents the half-open real time interval that starts with E+I*Time_Unit and is limited +by E+(I+1)*Time_Unit, where Time_Unit is an implementation-defined real number and E is an +unspecified origin point, the epoch, that is the same for all values of the type Time. It is not specified by +the language whether the time values are synchronized with any standard time reference. For example, E +can correspond to the time of system initialization or it can correspond to the epoch of some time standard. + +Values of the type Time_Span represent length of real time duration. The set of values of this type +corresponds one-to-one with an implementation-defined range of mathematical integers. The Time_Span +value corresponding to the integer I represents the real-time duration I*Time_Unit. + +Time_First and Time_Last are the smallest and largest values of the Time type, respectively. Similarly, +Time_Span_First and Time_Span_Last are the smallest and largest values of the Time_Span type, +respectively. + +22 + +A value of type Seconds_Count represents an elapsed time, measured in seconds, since the epoch. + +D.8 Monotonic Time + +13 December 2012 648 + + Ada Reference Manual — 2012 Edition + +Dynamic Semantics + +Time_Unit is the smallest amount of real time representable by the Time type; it is expressed in seconds. +Time_Span_Unit is the difference between two successive values of the Time type. It is also the smallest +positive value of type Time_Span. Time_Unit and Time_Span_Unit represent the same real time duration. +A clock tick is a real time interval during which the clock value (as observed by calling the Clock +function) remains constant. Tick is the average length of such intervals. + +The function To_Duration converts the value TS to a value of type Duration. Similarly, the function +To_Time_Span converts the value D to a value of type Time_Span. For To_Duration, the result is rounded +to the nearest value of type Duration (away from zero if exactly halfway between two values). If the result +is outside the range of Duration, Constraint_Error is raised. For To_Time_Span, the value of D is first +rounded to the nearest integral multiple of Time_Unit, away from zero if exactly halfway between two +multiples. If the rounded value is outside the range of Time_Span, Constraint_Error is raised. Otherwise, +the value is converted to the type Time_Span. + +To_Duration(Time_Span_Zero) returns 0.0, and To_Time_Span(0.0) returns Time_Span_Zero. + +The functions Nanoseconds, Microseconds, Milliseconds, Seconds, and Minutes convert the input +parameter to a value of the type Time_Span. NS, US, MS, S, and M are interpreted as a number of +nanoseconds, microseconds, milliseconds, seconds, and minutes respectively. The input parameter is first +converted to seconds and rounded to the nearest integral multiple of Time_Unit, away from zero if exactly +halfway between two multiples. If the rounded value is outside the range of Time_Span, Constraint_Error +is raised. Otherwise, the rounded value is converted to the type Time_Span. + +The effects of the operators on Time and Time_Span are as for the operators defined for integer types. + +The function Clock returns the amount of time since the epoch. + +The effects of the Split and Time_Of operations are defined as follows, treating values of type Time, +Time_Span, and Seconds_Count as mathematical integers. The effect of Split(T,SC,TS) is to set SC and +TS to values such that T*Time_Unit = SC*1.0 + TS*Time_Unit, and 0.0 <= TS*Time_Unit < 1.0. The +value returned by Time_Of(SC,TS) is the value T such that T*Time_Unit = SC*1.0 + TS*Time_Unit. + +Implementation Requirements + +The range of Time values shall be sufficient to uniquely represent the range of real times from program +start-up to 50 years later. Tick shall be no greater than 1 millisecond. Time_Unit shall be less than or equal +to 20 microseconds. + +Time_Span_First shall be no greater than –3600 seconds, and Time_Span_Last shall be no less than 3600 +seconds. + +A clock jump is the difference between two successive distinct values of the clock (as observed by calling +the Clock function). There shall be no backward clock jumps. + +Documentation Requirements + +The implementation shall document the values of Time_First, Time_Last, Time_Span_First, Time_Span_- +Last, Time_Span_Unit, and Tick. + +The implementation shall document the properties of the underlying time base used for the clock and for +type Time, such as the range of values supported and any relevant aspects of the underlying hardware or +operating system facilities used. + +23 + +24/2 + +25 + +26/2 + +27 + +28 + +29 + +30 + +31 + +32 + +33 + +34 + +649 13 December 2012 + +Monotonic Time D.8 + + Ada Reference Manual — 2012 Edition + +35 + +The implementation shall document whether or not there is any synchronization with external time +references, and if such synchronization exists, the sources of synchronization information, the frequency +of synchronization, and the synchronization method applied. + +36/3 + +The implementation shall document any aspects of the external environment that could interfere with the +clock behavior as defined in this subclause. + +37/3 + +For the purpose of the metrics defined in this subclause, real time is defined to be the International Atomic +Time (TAI). + +Metrics + +38 + +39 + +40 + +41 + +42 + +43 + +44 + +45 + +46 + +47 + +48 + +49 + +50/3 + +51 + +The implementation shall document the following metrics: + +• An upper bound on the real-time duration of a clock tick. This is a value D such that if t1 and t2 + +are any real times such that t1 < t2 and Clockt1 = Clockt2 then t2 – t1 <= D. + +• An upper bound on the size of a clock jump. +• An upper bound on the drift rate of Clock with respect to real time. This is a real number D such + +that + +E*(1–D) <= (Clockt+E – Clockt) <= E*(1+D) + provided that: Clockt + E*(1+D) <= Time_Last. + +• where Clockt is the value of Clock at time t, and E is a real time duration not less than 24 hours. + +The value of E used for this metric shall be reported. + +• An upper bound on the execution time of a call to the Clock function, in processor clock cycles. +• Upper bounds on the execution times of the operators of the types Time and Time_Span, in + +processor clock cycles. + +Implementations targeted to machines with word size smaller than 32 bits need not support the full range +and granularity of the Time and Time_Span types. + +Implementation Permissions + +Implementation Advice + +When appropriate, implementations should provide configuration mechanisms to change the value of Tick. + +It is recommended that Calendar.Clock and Real_Time.Clock be implemented as transformations of the +same time base. + +It is recommended that the “best” time base which exists in the underlying system be available to the +application through Clock. “Best” may mean highest accuracy or largest range. + +NOTES +35 The rules in this subclause do not imply that the implementation can protect the user from operator or installation +errors which could result in the clock being set incorrectly. + +36 Time_Unit is the granularity of the Time type. In contrast, Tick represents the granularity of Real_Time.Clock. There +is no requirement that these be the same. + +D.8 Monotonic Time + +13 December 2012 650 + + Ada Reference Manual — 2012 Edition + +D.9 Delay Accuracy + +This subclause specifies performance requirements for the delay_statement. The rules apply both to +delay_relative_statement and to delay_until_statement. Similarly, they apply equally to a simple delay_- +statement and to one which appears in a delay_alternative. + +1/3 + +Dynamic Semantics + +The effect of the delay_statement for Real_Time.Time is defined in terms of Real_Time.Clock: + +• If C1 is a value of Clock read before a task executes a delay_relative_statement with duration D, +and C2 is a value of Clock read after the task resumes execution following that delay_statement, +then C2 – C1 >= D. + +• If C is a value of Clock read after a task resumes execution following a delay_until_statement + +with Real_Time.Time value T, then C >= T. + +A simple delay_statement with a negative or zero value for the expiration time does not cause the calling +task to be blocked; it is nevertheless a potentially blocking operation (see 9.5.1). + +When a delay_statement appears in a delay_alternative of a timed_entry_call the selection of the entry +call is attempted, regardless of the specified expiration time. When a delay_statement appears in a +select_alternative, and a call is queued on one of the open entries, the selection of that entry call proceeds, +regardless of the value of the delay expression. + +Documentation Requirements + +implementation shall document + +The +delay_relative_statement that causes the task to actually be blocked. + +the minimum value of + +the delay expression of a + +The implementation shall document the minimum difference between the value of the delay expression of +a delay_until_statement and the value of Real_Time.Clock, that causes the task to actually be blocked. + +The implementation shall document the following metrics: + +Metrics + +• An upper bound on the execution time, in processor clock cycles, of a delay_relative_statement + +whose requested value of the delay expression is less than or equal to zero. + +• An upper bound on the execution time, in processor clock cycles, of a delay_until_statement +whose requested value of the delay expression is less than or equal to the value of +Real_Time.Clock at the time of executing the statement. Similarly, for Calendar.Clock. + +• An upper bound on the lateness of a delay_relative_statement, for a positive value of the delay +expression, in a situation where the task has sufficient priority to preempt the processor as soon +as it becomes ready, and does not need to wait for any other execution resources. The upper +bound is expressed as a function of the value of the delay expression. The lateness is obtained by +subtracting the value of the delay expression from the actual duration. The actual duration is +measured from a point immediately before a task executes the delay_statement to a point +immediately after the task resumes execution following this statement. + +• An upper bound on the lateness of a delay_until_statement, in a situation where the value of the +requested expiration time is after the time the task begins executing the statement, the task has +sufficient priority to preempt the processor as soon as it becomes ready, and it does not need to +wait for any other execution resources. The upper bound is expressed as a function of the +difference between the requested expiration time and the clock value at the time the statement +begins execution. The lateness of a delay_until_statement is obtained by subtracting the + +651 13 December 2012 + +Delay Accuracy D.9 + +2 + +3 + +4 + +5 + +6/3 + +7 + +8 + +9 + +10 + +11 + +12 + +13 + + Ada Reference Manual — 2012 Edition + +requested expiration time from the real time that the task resumes execution following this +statement. + +D.10 Synchronous Task Control + +1/3 + +This subclause describes a language-defined private semaphore (suspension object), which can be used for +two-stage suspend operations and as a simple building block for implementing higher-level queues. + +2 + +3/2 + +4 + +The following language-defined package exists: + +Static Semantics + +package Ada.Synchronous_Task_Control is + pragma Preelaborate(Synchronous_Task_Control); + type Suspension_Object is limited private; + procedure Set_True(S : in out Suspension_Object); + procedure Set_False(S : in out Suspension_Object); + function Current_State(S : Suspension_Object) return Boolean; + procedure Suspend_Until_True(S : in out Suspension_Object); +private + ... -- not specified by the language +end Ada.Synchronous_Task_Control; + +5 + +The type Suspension_Object is a by-reference type. + +5.1/3 + +5.2/3 + +6/2 + +7/2 + +The following language-defined package exists: + +package Ada.Synchronous_Task_Control.EDF is + procedure Suspend_Until_True_And_Set_Deadline + (S : in out Suspension_Object; + TS : in Ada.Real_Time.Time_Span); +end Ada.Synchronous_Task_Control.EDF; + +Dynamic Semantics + +An object of the type Suspension_Object has two visible states: True and False. Upon initialization, its +value is set to False. + +The operations Set_True and Set_False are atomic with respect to each other and with respect to +Suspend_Until_True; they set the state to True and False respectively. + +8 + +Current_State returns the current state of the object. + +9/2 + +10 + +10.1/3 + +The procedure Suspend_Until_True blocks the calling task until the state of the object S is True; at that +point the task becomes ready and the state of the object becomes False. + +Program_Error is raised upon calling Suspend_Until_True if another task is already waiting on that +suspension object. Suspend_Until_True is a potentially blocking operation (see 9.5.1). + +The procedure Suspend_Until_True_And_Set_Deadline blocks the calling task until the state of the object +S is True; at that point the task becomes ready with a deadline of Ada.Real_Time.Clock + TS, and the +state +calling +Suspend_Until_True_And_Set_Deadline if another task is already waiting on that suspension object. +Suspend_Until_True_And_Set_Deadline is a potentially blocking operation. + +Program_Error + +becomes + +object + +raised + +False. + +upon + +the + +of + +is + +11 + +The implementation is required to allow the calling of Set_False and Set_True during any protected action, +even one that has its ceiling priority in the Interrupt_Priority range. + +Implementation Requirements + +D.9 Delay Accuracy + +13 December 2012 652 + + Ada Reference Manual — 2012 Edition + +NOTES +37 More complex schemes, such as setting the deadline relative to when Set_True is called, can be programmed using a +protected object. + +12/3 + +D.10.1 Synchronous Barriers + +This subclause introduces a language-defined package to synchronously release a group of tasks after the +number of blocked tasks reaches a specified count value. + +1/3 + +Static Semantics + +The following language-defined library package exists: +package Ada.Synchronous_Barriers is + pragma Preelaborate(Synchronous_Barriers); + subtype Barrier_Limit is Positive range 1 .. implementation-defined; + type Synchronous_Barrier (Release_Threshold : Barrier_Limit) is limited +private; + procedure Wait_For_Release (The_Barrier : in out Synchronous_Barrier; + Notified : out Boolean); +private + -- not specified by the language +end Ada.Synchronous_Barriers; + +Type Synchronous_Barrier needs finalization (see 7.6). + +Dynamic Semantics + +Each call to Wait_For_Release blocks the calling task until the number of blocked tasks associated with +the Synchronous_Barrier object is equal to Release_Threshold, at which time all blocked tasks are +released. Notified is set to True for one of the released tasks, and set to False for all other released tasks. + +The mechanism for determining which task sets Notified to True is implementation defined. + +Once all tasks have been released, a Synchronous_Barrier object may be reused to block another +Release_Threshold number of tasks. + +As the first step of the finalization of a Synchronous_Barrier, each blocked task is unblocked and +Program_Error is raised at the place of the call to Wait_For_Release. + +It is implementation defined whether an abnormal task which is waiting on a Synchronous_Barrier object +is aborted immediately or aborted when the tasks waiting on the object are released. + +Wait_For_Release is a potentially blocking operation (see 9.5.1). + +Bounded (Run-Time) Errors + +It is a bounded error to call Wait_For_Release on a Synchronous_Barrier object after that object is +finalized. If the error is detected, Program_Error is raised. Otherwise, the call proceeds normally, which +may leave a task blocked forever. + +2/3 + +3/3 + +4/3 + +5/3 + +6/3 + +7/3 + +8/3 + +9/3 + +10/3 + +11/3 + +12/3 + +13/3 + +14/3 + +15/3 + +653 13 December 2012 + +Synchronous Task Control D.10 + + Ada Reference Manual — 2012 Edition + +D.11 Asynchronous Task Control + +1/3 + +This subclause introduces a language-defined package to do asynchronous suspend/resume on tasks. It +uses a conceptual held priority value to represent the task's held state. + +2 + +3/2 + +4/2 + +The following language-defined library package exists: + +Static Semantics + +with Ada.Task_Identification; +package Ada.Asynchronous_Task_Control is + pragma Preelaborate(Asynchronous_Task_Control); + procedure Hold(T : in Ada.Task_Identification.Task_Id); + procedure Continue(T : in Ada.Task_Identification.Task_Id); + function Is_Held(T : Ada.Task_Identification.Task_Id) + return Boolean; +end Ada.Asynchronous_Task_Control; + +Dynamic Semantics + +After the Hold operation has been applied to a task, the task becomes held. For each processor there is a +conceptual idle task, which is always ready. The base priority of the idle task is below System.Any_- +Priority'First. The held priority is a constant of the type Integer whose value is below the base priority of +the idle task. + +4.1/2 + +For any priority below System.Any_Priority'First, the task dispatching policy is FIFO_Within_Priorities. + +5/2 + +6/2 + +7 + +8 + +9 + +10 + +11 + +12 + +13 + +14 + +15 + +16 + +The Hold operation sets the state of T to held. For a held task, the active priority is reevaluated as if the +base priority of the task were the held priority. + +The Continue operation resets the state of T to not-held; its active priority is then reevaluated as +determined by the task dispatching policy associated with its base priority. + +The Is_Held function returns True if and only if T is in the held state. + +As part of these operations, a check is made that the task identified by T is not terminated. Tasking_Error +is raised if the check fails. Program_Error is raised if the value of T is Null_Task_Id. + +If any operation in this package is called with a parameter T that specifies a task object that no longer +exists, the execution of the program is erroneous. + +Erroneous Execution + +Implementation Permissions + +An implementation need not support Asynchronous_Task_Control if it is infeasible to support it in the +target environment. + +NOTES +38 It is a consequence of the priority rules that held tasks cannot be dispatched on any processor in a partition (unless +they are inheriting priorities) since their priorities are defined to be below the priority of any idle task. + +39 The effect of calling Get_Priority and Set_Priority on a Held task is the same as on any other task. + +40 Calling Hold on a held task or Continue on a non-held task has no effect. + +41 The rules affecting queuing are derived from the above rules, in addition to the normal priority rules: + +• When a held task is on the ready queue, its priority is so low as to never reach the top of the queue as long as + +there are other tasks on that queue. + +• + +If a task is executing in a protected action, inside a rendezvous, or is inheriting priorities from other sources +(e.g. when activated), it continues to execute until it is no longer executing the corresponding construct. + +D.11 Asynchronous Task Control + +13 December 2012 654 + + Ada Reference Manual — 2012 Edition + +• + +• + +If a task becomes held while waiting (as a caller) for a rendezvous to complete, the active priority of the +accepting task is not affected. + +If a task becomes held while waiting in a selective_accept, and an entry call is issued to one of the open +entries, the corresponding accept_alternative executes. When the rendezvous completes, the active priority of +the accepting task is lowered to the held priority (unless it is still inheriting from other sources), and the task +does not execute until another Continue. + +17 + +18/1 + +• The same holds if the held task is the only task on a protected entry queue whose barrier becomes open. The + +19 + +corresponding entry body executes. + +D.12 Other Optimizations and Determinism Rules + +This subclause describes various requirements for improving the response and determinism in a real-time +system. + +1/3 + +Implementation Requirements + +If the implementation blocks interrupts (see C.3) not as a result of direct user action (e.g. an execution of a +protected action) there shall be an upper bound on the duration of this blocking. + +The implementation shall recognize entry-less protected types. The overhead of acquiring the execution +resource of an object of such a type (see 9.5.1) shall be minimized. In particular, there should not be any +overhead due to evaluating entry_barrier conditions. + +Unchecked_Deallocation shall be supported for terminated tasks that are designated by access types, and +shall have the effect of releasing all the storage associated with the task. This includes any run-time system +or heap storage that has been implicitly allocated for the task by the implementation. + +The implementation shall document the upper bound on the duration of interrupt blocking caused by the +implementation. If this is different for different interrupts or interrupt priority levels, it should be +documented for each case. + +Documentation Requirements + +The implementation shall document the following metric: + +Metrics + +• The overhead associated with obtaining a mutual-exclusive access to an entry-less protected + +object. This shall be measured in the following way: + + For a protected object of the form: + +protected Lock is + procedure Set; + function Read return Boolean; +private + Flag : Boolean := False; +end Lock; +protected body Lock is + procedure Set is + begin + Flag := True; + end Set; + function Read return Boolean + Begin + return Flag; + end Read; +end Lock; + +2 + +3 + +4 + +5 + +6 + +7 + +8 + +9 + +10 + +655 13 December 2012 + +Asynchronous Task Control D.11 + + Ada Reference Manual — 2012 Edition + +11 + + The execution time, in processor clock cycles, of a call to Set. This shall be measured between +the point just before issuing the call, and the point just after the call completes. The function +Read shall be called later to verify that Set was indeed called (and not optimized away). The +calling task shall have sufficiently high priority as to not be preempted during the measurement +period. The protected object shall have sufficiently high ceiling priority to allow the task to call +Set. + +12 + + For a multiprocessor, if supported, the metric shall be reported for the case where no contention + +(on the execution resource) exists from tasks executing on other processors. + +D.13 The Ravenscar Profile + +1/3 + +This subclause defines the Ravenscar profile. + +Paragraphs 2 and 3 were moved to 13.12, “Pragma Restrictions and Pragma Profile”. + +4/3 + +The profile_identifier Ravenscar is a usage profile (see 13.12). For usage profile Ravenscar, there shall be +no profile_pragma_argument_associations. + +Legality Rules + +5/3 + +6/3 + +The usage profile Ravenscar is equivalent to the following set of pragmas: + +Static Semantics + +pragma Task_Dispatching_Policy (FIFO_Within_Priorities); +pragma Locking_Policy (Ceiling_Locking); +pragma Detect_Blocking; +pragma Restrictions ( + No_Abort_Statements, + No_Dynamic_Attachment, + No_Dynamic_Priorities, + No_Implicit_Heap_Allocations, + No_Local_Protected_Objects, + No_Local_Timing_Events, + No_Protected_Type_Allocators, + No_Relative_Delay, + No_Requeue_Statements, + No_Select_Statements, + No_Specific_Termination_Handlers, + No_Task_Allocators, + No_Task_Hierarchy, + No_Task_Termination, + Simple_Barriers, + Max_Entry_Queue_Length => 1, + Max_Protected_Entries => 1, + Max_Task_Entries => 0, + No_Dependence => Ada.Asynchronous_Task_Control, + No_Dependence => Ada.Calendar, + No_Dependence => Ada.Execution_Time.Group_Budgets, + No_Dependence => Ada.Execution_Time.Timers, + No_Dependence => Ada.Task_Attributes, + No_Dependence => System.Multiprocessors.Dispatching_Domains); + +Paragraph 7 was deleted. + +8/3 + +A task shall only be on the ready queues of one processor, and the processor to which a task belongs shall +be defined statically. Whenever a task running on a processor reaches a task dispatching point, it goes +back to the ready queues of the same processor. A task with a CPU value of Not_A_Specific_CPU will + +Implementation Requirements + +D.12 Other Optimizations and Determinism Rules + +13 December 2012 656 + + Ada Reference Manual — 2012 Edition + +execute on an implementation defined processor. A task without a CPU aspect will activate and execute on +the same processor as its activating task. + +Implementation Advice + +On a multiprocessor system, an implementation should support a fully partitioned approach. Each +processor should have separate and disjoint ready queues. + +9/3 + +NOTES +42 The effect of the Max_Entry_Queue_Length => 1 restriction applies only to protected entry queues due to the +accompanying restriction of Max_Task_Entries => 0. + +10/3 + +D.14 Execution Time + +This subclause describes a language-defined package to measure execution time. + +The following language-defined library package exists: + +Static Semantics + +with Ada.Task_Identification; +with Ada.Real_Time; use Ada.Real_Time; +package Ada.Execution_Time is + type CPU_Time is private; + CPU_Time_First : constant CPU_Time; + CPU_Time_Last : constant CPU_Time; + CPU_Time_Unit : constant := implementation-defined-real-number; + CPU_Tick : constant Time_Span; + function Clock + (T : Ada.Task_Identification.Task_Id + := Ada.Task_Identification.Current_Task) + return CPU_Time; + function "+" (Left : CPU_Time; Right : Time_Span) return CPU_Time; + function "+" (Left : Time_Span; Right : CPU_Time) return CPU_Time; + function "-" (Left : CPU_Time; Right : Time_Span) return CPU_Time; + function "-" (Left : CPU_Time; Right : CPU_Time) return Time_Span; + function "<" (Left, Right : CPU_Time) return Boolean; + function "<=" (Left, Right : CPU_Time) return Boolean; + function ">" (Left, Right : CPU_Time) return Boolean; + function ">=" (Left, Right : CPU_Time) return Boolean; + procedure Split + (T : in CPU_Time; SC : out Seconds_Count; TS : out Time_Span); + function Time_Of (SC : Seconds_Count; + TS : Time_Span := Time_Span_Zero) return CPU_Time; + Interrupt_Clocks_Supported : constant Boolean := implementation-defined; + Separate_Interrupt_Clocks_Supported : constant Boolean := + implementation-defined; + function Clock_For_Interrupts return CPU_Time; +private + ... -- not specified by the language +end Ada.Execution_Time; + +The execution time or CPU time of a given task is defined as the time spent by the system executing that +task, including the time spent executing run-time or system services on its behalf. The mechanism used to +measure execution time is implementation defined. The Boolean constant Interrupt_Clocks_Supported is +set to True if the implementation separately accounts for the execution time of interrupt handlers. If it is +set to False it is implementation defined which task, if any, is charged the execution time that is consumed + +657 13 December 2012 + +The Ravenscar Profile D.13 + +1/3 + +2/2 + +3/2 + +4/2 + +5/2 + +6/2 + +7/2 + +8/2 + +9/2 + +9.1/3 + +9.2/3 + +9.3/3 + +10/2 + +11/3 + + Ada Reference Manual — 2012 Edition + +12/2 + +13/2 + +by interrupt handlers. The Boolean constant Separate_Interrupt_Clocks_Supported is set to True if the +implementation separately accounts for the execution time of individual interrupt handlers (see D.14.3). + +The type CPU_Time represents the execution time of a task. The set of values of this type corresponds +one-to-one with an implementation-defined range of mathematical integers. + +The CPU_Time value I represents the half-open execution-time interval that starts with I*CPU_Time_Unit +and is limited by (I+1)*CPU_Time_Unit, where CPU_Time_Unit is an implementation-defined real +number. For each task, the execution time value is set to zero at the creation of the task. + +14/2 + +CPU_Time_First and CPU_Time_Last are the smallest and largest values of the CPU_Time type, +respectively. + +14.1/3 + +The execution time value for the function Clock_For_Interrupts is initialized to zero. + +Dynamic Semantics + +15/2 + +16/2 + +17/2 + +18/2 + +CPU_Time_Unit is the smallest amount of execution time representable by the CPU_Time type; it is +expressed in seconds. A CPU clock tick is an execution time interval during which the clock value (as +observed by calling the Clock function) remains constant. CPU_Tick is the average length of such +intervals. + +The effects of the operators on CPU_Time and Time_Span are as for the operators defined for integer +types. + +The function Clock returns the current execution time of the task identified by T; Tasking_Error is raised +if that task has terminated; Program_Error is raised if the value of T is Task_Identification.Null_Task_Id. + +The effects of the Split and Time_Of operations are defined as follows, treating values of type CPU_Time, +Time_Span, and Seconds_Count as mathematical integers. The effect of Split (T, SC, TS) is to set SC and +TS +that T*CPU_Time_Unit = SC*1.0 + TS*CPU_Time_Unit, and 0.0 <= +TS*CPU_Time_Unit < 1.0. The value returned by Time_Of(SC,TS) is the execution-time value T such +that T*CPU_Time_Unit=SC*1.0 + TS*CPU_Time_Unit. + +to values such + +18.1/3 + +The function Clock_For_Interrupts returns the total cumulative time spent executing within all interrupt +handlers. This time is not allocated to any task execution time clock. If Interrupt_Clocks_Supported is set +to False the function raises Program_Error. + +19/2 + +For a call of Clock, if the task identified by T no longer exists, the execution of the program is erroneous. + +Erroneous Execution + +20/2 + +The range of CPU_Time values shall be sufficient to uniquely represent the range of execution times from +the task start-up to 50 years of execution time later. CPU_Tick shall be no greater than 1 millisecond. + +Implementation Requirements + +Documentation Requirements + +21/2 + +22/2 + +The implementation shall document the values of CPU_Time_First, CPU_Time_Last, CPU_Time_Unit, +and CPU_Tick. + +The implementation shall document the properties of the underlying mechanism used to measure +execution times, such as the range of values supported and any relevant aspects of the underlying +hardware or operating system facilities used. + +D.14 Execution Time + +13 December 2012 658 + + Ada Reference Manual — 2012 Edition + +The implementation shall document the following metrics: + +Metrics + +• An upper bound on the execution-time duration of a clock tick. This is a value D such that if t1 +and t2 are any execution times of a given task such that t1 < t2 and Clockt1 = Clockt2 then t2 – t1 +<= D. + +• An upper bound on the size of a clock jump. A clock jump is the difference between two +successive distinct values of an execution-time clock (as observed by calling the Clock function +with the same Task_Id). + +• An upper bound on the execution time of a call to the Clock function, in processor clock cycles. +• Upper bounds on the execution times of the operators of the type CPU_Time, in processor clock + +cycles. + +23/2 + +24/2 + +25/2 + +26/2 + +27/2 + +Implementations targeted to machines with word size smaller than 32 bits need not support the full range +and granularity of the CPU_Time type. + +28/2 + +Implementation Permissions + +When appropriate, implementations should provide configuration mechanisms to change the value of +CPU_Tick. + +29/2 + +Implementation Advice + +D.14.1 Execution Time Timers + +This subclause describes a language-defined package that provides a facility for calling a handler when a +task has used a defined amount of CPU time. + +1/3 + +The following language-defined library package exists: + +Static Semantics + +with System; +package Ada.Execution_Time.Timers is + type Timer (T : not null access constant + Ada.Task_Identification.Task_Id) is + tagged limited private; + type Timer_Handler is + access protected procedure (TM : in out Timer); + Min_Handler_Ceiling : constant System.Any_Priority := + implementation-defined; + procedure Set_Handler (TM : in out Timer; + In_Time : in Time_Span; + Handler : in Timer_Handler); + procedure Set_Handler (TM : in out Timer; + At_Time : in CPU_Time; + Handler : in Timer_Handler); + function Current_Handler (TM : Timer) return Timer_Handler; + procedure Cancel_Handler (TM : in out Timer; + Cancelled : out Boolean); + function Time_Remaining (TM : Timer) return Time_Span; + Timer_Resource_Error : exception; +private + ... -- not specified by the language +end Ada.Execution_Time.Timers; + +2/2 + +3/2 + +4/2 + +5/2 + +6/2 + +7/2 + +8/2 + +9/2 + +10/2 + +659 13 December 2012 + +Execution Time D.14 + + Ada Reference Manual — 2012 Edition + +11/2 + +12/2 + +13/2 + +14/2 + +15/3 + +16/2 + +17/2 + +18/3 + +19/3 + +20/3 + +21/2 + +The type Timer represents an execution-time event for a single task and is capable of detecting execution- +time overruns. The access discriminant T identifies the task concerned. The type Timer needs finalization +(see 7.6). + +An object of type Timer is said to be set if it is associated with a nonnull value of type Timer_Handler and +cleared otherwise. All Timer objects are initially cleared. + +The type Timer_Handler identifies a protected procedure to be executed by the implementation when the +timer expires. Such a protected procedure is called a handler. + +Dynamic Semantics + +When a Timer object is created, or upon the first call of a Set_Handler procedure with the timer as +parameter, the resources required to operate an execution-time timer based on the associated execution- +time clock are allocated and initialized. If this operation would exceed the available resources, +Timer_Resource_Error is raised. + +The procedures Set_Handler associate the handler Handler with the timer TM: if Handler is null, the timer +is cleared; otherwise, it is set. The first procedure Set_Handler loads the timer TM with an interval +specified by the Time_Span parameter. In this mode, the timer TM expires when the execution time of the +task identified by TM.T.all has increased by In_Time; if In_Time is less than or equal to zero, the timer +expires immediately. The second procedure Set_Handler loads the timer TM with the absolute value +specified by At_Time. In this mode, the timer TM expires when the execution time of the task identified +by TM.T.all reaches At_Time; if the value of At_Time has already been reached when Set_Handler is +called, the timer expires immediately. + +A call of a procedure Set_Handler for a timer that is already set replaces the handler and the (absolute or +relative) execution time; if Handler is not null, the timer remains set. + +When a timer expires, the associated handler is executed, passing the timer as parameter. The initial action +of the execution of the handler is to clear the event. + +The function Current_Handler returns the handler associated with the timer TM if that timer is set; +otherwise, it returns null. + +The procedure Cancel_Handler clears the timer if it is set. Cancelled is assigned True if the timer was set +prior to it being cleared; otherwise, it is assigned False. + +The function Time_Remaining returns the execution time interval that remains until the timer TM would +expire, if that timer is set; otherwise, it returns Time_Span_Zero. + +The constant Min_Handler_Ceiling is the minimum ceiling priority required for a protected object with a +handler to ensure that no ceiling violation will occur when that handler is invoked. + +22/2 + +As part of the finalization of an object of type Timer, the timer is cleared. + +23/2 + +For all the subprograms defined in this package, Tasking_Error is raised if the task identified by TM.T.all +has terminated, and Program_Error is raised if the value of TM.T.all is Task_Identification.Null_Task_Id. + +24/2 + +An exception propagated from a handler invoked as part of the expiration of a timer has no effect. + +25/2 + +For a call of any of the subprograms defined in this package, if the task identified by TM.T.all no longer +exists, the execution of the program is erroneous. + +Erroneous Execution + +D.14.1 Execution Time Timers + +13 December 2012 660 + + Ada Reference Manual — 2012 Edition + +Implementation Requirements + +For a given Timer object, the implementation shall perform the operations declared in this package +atomically with respect to any of these operations on the same Timer object. The replacement of a handler +by a call of Set_Handler shall be performed atomically with respect to the execution of the handler. + +26/2 + +When an object of type Timer is finalized, the system resources used by the timer shall be deallocated. + +27/2 + +Implementation Permissions + +Implementations may limit the number of timers that can be defined for each task. If this limit is exceeded, +then Timer_Resource_Error is raised. + +28/3 + +NOTES +43 A Timer_Handler can be associated with several Timer objects. + +29/2 + +D.14.2 Group Execution Time Budgets + +This subclause describes a language-defined package to assign execution time budgets to groups of tasks. + +1/3 + +The following language-defined library package exists: + +Static Semantics + +with System; +with System.Multiprocessors; +package Ada.Execution_Time.Group_Budgets is + type Group_Budget(CPU : System.Multiprocessors.CPU := + System.Multiprocessors.CPU'First) + is tagged limited private; + type Group_Budget_Handler is access + protected procedure (GB : in out Group_Budget); + type Task_Array is array (Positive range <>) of + Ada.Task_Identification.Task_Id; + Min_Handler_Ceiling : constant System.Any_Priority := + implementation-defined; + procedure Add_Task (GB : in out Group_Budget; + T : in Ada.Task_Identification.Task_Id); + procedure Remove_Task (GB: in out Group_Budget; + T : in Ada.Task_Identification.Task_Id); + function Is_Member (GB : Group_Budget; + T : Ada.Task_Identification.Task_Id) return Boolean; + function Is_A_Group_Member + (T : Ada.Task_Identification.Task_Id) return Boolean; + function Members (GB : Group_Budget) return Task_Array; + procedure Replenish (GB : in out Group_Budget; To : in Time_Span); + procedure Add (GB : in out Group_Budget; Interval : in Time_Span); + function Budget_Has_Expired (GB : Group_Budget) return Boolean; + function Budget_Remaining (GB : Group_Budget) return Time_Span; + procedure Set_Handler (GB : in out Group_Budget; + Handler : in Group_Budget_Handler); + function Current_Handler (GB : Group_Budget) + return Group_Budget_Handler; + procedure Cancel_Handler (GB : in out Group_Budget; + Cancelled : out Boolean); + Group_Budget_Error : exception; +private + -- not specified by the language +end Ada.Execution_Time.Group_Budgets; + +2/2 + +3/3 + +4/3 + +5/2 + +6/2 + +7/2 + +8/2 + +9/2 + +10/2 + +11/2 + +12/2 + +661 13 December 2012 + +Execution Time Timers D.14.1 + + Ada Reference Manual — 2012 Edition + +13/2 + +14/2 + +15/2 + +16/2 + +17/2 + +18/3 + +19/3 + +20/2 + +21/3 + +22/2 + +23/3 + +24/2 + +25/3 + +26/2 + +27/3 + +The type Group_Budget represents an execution time budget to be used by a group of tasks. The type +Group_Budget needs finalization (see 7.6). A task can belong to at most one group. Tasks of any priority +can be added to a group. + +An object of type Group_Budget has an associated nonnegative value of type Time_Span known as its +budget, which is initially Time_Span_Zero. The type Group_Budget_Handler identifies a protected +procedure to be executed by the implementation when the budget is exhausted, that is, reaches zero. Such +a protected procedure is called a handler. + +An object of type Group_Budget also includes a handler, which is a value of type Group_Budget_Handler. +The handler of the object is said to be set if it is not null and cleared otherwise. The handler of all +Group_Budget objects is initially cleared. + +Dynamic Semantics + +The procedure Add_Task adds the task identified by T to the group GB; if that task is already a member of +some other group, Group_Budget_Error is raised. + +The procedure Remove_Task removes the task identified by T from the group GB; if that task is not a +member of the group GB, Group_Budget_Error is raised. After successful execution of this procedure, the +task is no longer a member of any group. + +The function Is_Member returns True if the task identified by T is a member of the group GB; otherwise, +it returns False. + +The function Is_A_Group_Member returns True if the task identified by T is a member of some group; +otherwise, it returns False. + +The function Members returns an array of values of type Task_Identification.Task_Id identifying the +members of the group GB. The order of the components of the array is unspecified. + +The procedure Replenish loads the group budget GB with To as the Time_Span value. The exception +Group_Budget_Error is raised if the Time_Span value To is nonpositive. Any execution on CPU of any +member of the group of tasks results in the budget counting down, unless exhausted. When the budget +becomes exhausted (reaches Time_Span_Zero), the associated handler is executed if the handler of group +budget GB is set. Nevertheless, the tasks continue to execute. + +The procedure Add modifies the budget of the group GB. A positive value for Interval increases the +budget. A negative value for Interval reduces the budget, but never below Time_Span_Zero. A zero value +for Interval has no effect. A call of procedure Add that results in the value of the budget going to +Time_Span_Zero causes the associated handler to be executed if the handler of the group budget GB is set. + +The function Budget_Has_Expired returns True if the budget of group GB is exhausted (equal to +Time_Span_Zero); otherwise, it returns False. + +The function Budget_Remaining returns the remaining budget for the group GB. If the budget is exhausted +it returns Time_Span_Zero. This is the minimum value for a budget. + +The procedure Set_Handler associates the handler Handler with the Group_Budget GB: if Handler is null, +the handler of Group_Budget is cleared; otherwise, it is set. + +A call of Set_Handler for a Group_Budget that already has a handler set replaces the handler; if Handler is +not null, the handler for Group_Budget remains set. + +The function Current_Handler returns the handler associated with the group budget GB if the handler for +that group budget is set; otherwise, it returns null. + +D.14.2 Group Execution Time Budgets + +13 December 2012 662 + + Ada Reference Manual — 2012 Edition + +The procedure Cancel_Handler clears the handler for the group budget if it is set. Cancelled is assigned +True if the handler for the group budget was set prior to it being cleared; otherwise, it is assigned False. + +The constant Min_Handler_Ceiling is the minimum ceiling priority required for a protected object with a +handler to ensure that no ceiling violation will occur when that handler is invoked. + +The precision of the accounting of task execution time to a Group_Budget is the same as that defined for +execution-time clocks from the parent package. + +As part of the finalization of an object of type Group_Budget all member tasks are removed from the +group identified by that object. + +If a task is a member of a Group_Budget when it terminates, then as part of the finalization of the task it is +removed from the group. + +For all the operations defined in this package, Tasking_Error is raised if the task identified by T has +terminated, and Program_Error is raised if the value of T is Task_Identification.Null_Task_Id. + +An exception propagated from a handler invoked when the budget of a group of tasks becomes exhausted +has no effect. + +28/3 + +29/2 + +30/2 + +31/2 + +32/3 + +33/2 + +34/2 + +For a call of any of the subprograms defined in this package, if the task identified by T no longer exists, +the execution of the program is erroneous. + +35/2 + +Erroneous Execution + +Implementation Requirements + +For a given Group_Budget object, the implementation shall perform the operations declared in this +package atomically with respect to any of these operations on the same Group_Budget object. The +replacement of a handler, by a call of Set_Handler, shall be performed atomically with respect to the +execution of the handler. + +NOTES +44 Clearing or setting of the handler of a group budget does not change the current value of the budget. Exhaustion or +loading of a budget does not change whether the handler of the group budget is set or cleared. + +45 A Group_Budget_Handler can be associated with several Group_Budget objects. + +36/2 + +37/2 + +38/2 + +D.14.3 Execution Time of Interrupt Handlers + +This subclause describes a language-defined package to measure the execution time of interrupt handlers. + +1/3 + +The following language-defined library package exists: + +Static Semantics + +with Ada.Interrupts; +package Ada.Execution_Time.Interrupts is + function Clock (Interrupt : Ada.Interrupts.Interrupt_Id) + return CPU_Time; + function Supported (Interrupt : Ada.Interrupts.Interrupt_Id) + return Boolean; +end Ada.Execution_Time.Interrupts; + +The execution time or CPU time of a given interrupt Interrupt is defined as the time spent by the system +executing interrupt handlers identified by Interrupt, including the time spent executing run-time or system +services on its behalf. The mechanism used to measure execution time is implementation defined. Time +spent executing interrupt handlers is distinct from time spent executing any task. + +2/3 + +3/3 + +4/3 + +663 13 December 2012 + +Group Execution Time Budgets D.14.2 + + Ada Reference Manual — 2012 Edition + +5/3 + +For each interrupt, the execution time value is initially set to zero. + +Dynamic Semantics + +6/3 + +7/3 + +The function Clock returns the current cumulative execution time of the interrupt identified by Interrupt. If +Separate_Interrupt_Clocks_Supported is set to False the function raises Program_Error. + +The function Supported returns True if the implementation is monitoring the execution time of the +interrupt identified by Interrupt; otherwise, it returns False. For any Interrupt_Id Interrupt for which +to +Supported(Interrupt) returns False, +Ada.Execution_Time.Time_Of(0). + +the function Clock(Interrupt) will return a value equal + +D.15 Timing Events + +1/3 + +This subclause describes a language-defined package to allow user-defined protected procedures to be +executed at a specified time without the need for a task or a delay statement. + +2/2 + +3/2 + +4/2 + +5/2 + +6/2 + +7/2 + +8/2 + +9/2 + +Static Semantics + +The following language-defined library package exists: +package Ada.Real_Time.Timing_Events is + type Timing_Event is tagged limited private; + type Timing_Event_Handler + is access protected procedure (Event : in out Timing_Event); + procedure Set_Handler (Event : in out Timing_Event; + At_Time : in Time; + Handler : in Timing_Event_Handler); + procedure Set_Handler (Event : in out Timing_Event; + In_Time : in Time_Span; + Handler : in Timing_Event_Handler); + function Current_Handler (Event : Timing_Event) + return Timing_Event_Handler; + procedure Cancel_Handler (Event : in out Timing_Event; + Cancelled : out Boolean); + function Time_Of_Event (Event : Timing_Event) return Time; +private + ... -- not specified by the language +end Ada.Real_Time.Timing_Events; + +The type Timing_Event represents a time in the future when an event is to occur. The type Timing_Event +needs finalization (see 7.6). + +An object of type Timing_Event is said to be set if it is associated with a nonnull value of type +Timing_Event_Handler and cleared otherwise. All Timing_Event objects are initially cleared. + +10/2 + +The type Timing_Event_Handler identifies a protected procedure to be executed by the implementation +when the timing event occurs. Such a protected procedure is called a handler. + +Dynamic Semantics + +11/3 + +The procedures Set_Handler associate the handler Handler with the event Event: if Handler is null, the +event is cleared; otherwise, it is set. The first procedure Set_Handler sets the execution time for the event +to be At_Time. The second procedure Set_Handler sets the execution time for the event to be +Real_Time.Clock + In_Time. + +12/2 + +A call of a procedure Set_Handler for an event that is already set replaces the handler and the time of +execution; if Handler is not null, the event remains set. + +D.14.3 Execution Time of Interrupt Handlers + +13 December 2012 664 + + Ada Reference Manual — 2012 Edition + +As soon as possible after the time set for the event, the handler is executed, passing the event as parameter. +The handler is only executed if the timing event is in the set state at the time of execution. The initial +action of the execution of the handler is to clear the event. + +If the Ceiling_Locking policy (see D.3) is in effect when a procedure Set_Handler is called, a check is +made that the ceiling priority of Handler.all is Interrupt_Priority'Last. If the check fails, Program_Error is +raised. + +If a procedure Set_Handler is called with zero or negative In_Time or with At_Time indicating a time in +the past, then the handler is executed as soon as possible after the completion of the call of Set_Handler. + +The function Current_Handler returns the handler associated with the event Event if that event is set; +otherwise, it returns null. + +The procedure Cancel_Handler clears the event if it is set. Cancelled is assigned True if the event was set +prior to it being cleared; otherwise, it is assigned False. + +The function Time_Of_Event returns the time of the event if the event is set; otherwise, it returns +Real_Time.Time_First. + +As part of the finalization of an object of type Timing_Event, the Timing_Event is cleared. + +If several timing events are set for the same time, they are executed in FIFO order of being set. + +An exception propagated from a handler invoked by a timing event has no effect. + +Implementation Requirements + +For a given Timing_Event object, the implementation shall perform the operations declared in this +package atomically with respect to any of these operations on the same Timing_Event object. The +replacement of a handler by a call of Set_Handler shall be performed atomically with respect to the +execution of the handler. + +The implementation shall document the following metric: + +Metrics + +• An upper bound on the lateness of the execution of a handler. That is, the maximum time +between the time specified for the event and when a handler is actually invoked assuming no +other handler or task is executing during this interval. + +13/2 + +14/2 + +15/3 + +16/3 + +17/3 + +18/3 + +19/2 + +20/2 + +21/2 + +22/2 + +23/2 + +24/3 + +Implementation Advice + +The protected handler procedure should be executed directly by the real-time clock interrupt mechanism. + +25/2 + +NOTES +46 Since a call of Set_Handler is not a potentially blocking operation, it can be called from within a handler. + +47 A Timing_Event_Handler can be associated with several Timing_Event objects. + +26/2 + +27/2 + +665 13 December 2012 + +Timing Events D.15 + + Ada Reference Manual — 2012 Edition + +D.16 Multiprocessor Implementation + +1/3 + +This subclause allows implementations on multiprocessor platforms to be configured. + +2/3 + +3/3 + +4/3 + +5/3 + +6/3 + +7/3 + +Static Semantics + +The following language-defined library package exists: +package System.Multiprocessors is + pragma Preelaborate(Multiprocessors); + type CPU_Range is range 0 .. implementation-defined; + Not_A_Specific_CPU : constant CPU_Range := 0; + subtype CPU is CPU_Range range 1 .. CPU_Range'Last; + function Number_Of_CPUs return CPU; +end System.Multiprocessors; + +A call of Number_Of_CPUs returns the number of processors available to the program. Within a given +partition, each call on Number_Of_CPUs will return the same value. + +For a task type (including the anonymous type of a single_task_declaration) or subprogram, the following +language-defined representation aspect may be specified: + +8/3 + +CPU + +aspect + +The +System.Multiprocessors.CPU_Range. + +CPU + +an + +is + +expression, which + +shall + +be + +of + +type + +9/3 + +If the CPU aspect is specified for a subprogram, the expression shall be static. + +10/3 + +The CPU aspect shall not be specified on a task interface type. + +Legality Rules + +Dynamic Semantics + +11/3 + +12/3 + +13/3 + +14/3 + +The expression specified for the CPU aspect of a task is evaluated for each task object (see 9.1). The CPU +value is then associated with the task object whose task declaration specifies the aspect. + +The CPU aspect has no effect if it is specified for a subprogram other than the main subprogram; the CPU +value is not associated with any task. + +The CPU value is associated with the environment task if the CPU aspect is specified for the main +subprogram. If the CPU aspect is not specified for the main subprogram it is implementation defined on +which processor the environment task executes. + +The CPU value determines the processor on which the task will activate and execute; the task is said to be +assigned to that processor. If the CPU value is Not_A_Specific_CPU, then the task is not assigned to a +processor. A task without a CPU aspect specified will activate and execute on the same processor as its +activating task if the activating task is assigned a processor. If the CPU value is not in the range of +System.Multiprocessors.CPU_Range or is greater than Number_Of_CPUs the task is defined to have +failed, and it becomes a completed task (see 9.2). + +D.16 Multiprocessor Implementation + +13 December 2012 666 + + Ada Reference Manual — 2012 Edition + +D.16.1 Multiprocessor Dispatching Domains + +This subclause allows implementations on multiprocessor platforms to be partitioned into distinct +dispatching domains during program startup. + +1/3 + +The following language-defined library package exists: + +Static Semantics + +with Ada.Real_Time; +with Ada.Task_Identification; +package System.Multiprocessors.Dispatching_Domains is + Dispatching_Domain_Error : exception; + type Dispatching_Domain (<>) is limited private; + System_Dispatching_Domain : constant Dispatching_Domain; + function Create (First, Last : CPU) return Dispatching_Domain; + function Get_First_CPU (Domain : Dispatching_Domain) return CPU; + function Get_Last_CPU (Domain : Dispatching_Domain) return CPU; + function Get_Dispatching_Domain + (T : Ada.Task_Identification.Task_Id := + Ada.Task_Identification.Current_Task) + return Dispatching_Domain; + procedure Assign_Task + (Domain : in out Dispatching_Domain; + CPU : in CPU_Range := Not_A_Specific_CPU; + T : in Ada.Task_Identification.Task_Id := + Ada.Task_Identification.Current_Task); + procedure Set_CPU + (CPU : in CPU_Range; + T : in Ada.Task_Identification.Task_Id := + Ada.Task_Identification.Current_Task); + function Get_CPU + (T : Ada.Task_Identification.Task_Id := + Ada.Task_Identification.Current_Task) + return CPU_Range; + procedure Delay_Until_And_Set_CPU + (Delay_Until_Time : in Ada.Real_Time.Time; CPU : in CPU_Range); +private + ... -- not specified by the language +end System.Multiprocessors.Dispatching_Domains; + +The type Dispatching_Domain represents a series of processors on which a task may execute. Each +processor is contained within exactly one Dispatching_Domain. System_Dispatching_Domain contains the +processor or processors on which the environment task executes. At program start-up all processors are +contained within System_Dispatching_Domain. + +For a task type (including the anonymous type of a single_task_declaration), the following language- +defined representation aspect may be specified: + +Dispatching_Domain + +The value of aspect Dispatching_Domain is an expression, which shall be of type +Dispatching_Domains.Dispatching_Domain. This aspect is the domain to which the task (or +all objects of the task type) are assigned. + +The Dispatching_Domain aspect shall not be specified for a task interface. + +Legality Rules + +667 13 December 2012 + +Multiprocessor Dispatching Domains D.16.1 + +2/3 + +3/3 + +4/3 + +5/3 + +6/3 + +7/3 + +8/3 + +9/3 + +10/3 + +11/3 + +12/3 + +13/3 + +14/3 + +15/3 + +16/3 + +17/3 + +18/3 + +19/3 + + + Ada Reference Manual — 2012 Edition + +Dynamic Semantics + +20/3 + +21/3 + +22/3 + +23/3 + +The expression specified for the Dispatching_Domain aspect of a task is evaluated for each task object +(see 9.1). The Dispatching_Domain value is then associated with the task object whose task declaration +specifies the aspect. + +If a task is not explicitly assigned to any domain, it is assigned to that of the activating task. A task always +executes on some CPU in its domain. + +If both Dispatching_Domain and CPU are specified for a task, and the CPU value is not contained within +the range of processors for the domain (and is not Not_A_Specific_CPU), the activation of the task is +defined to have failed, and it becomes a completed task (see 9.2). + +The function Create creates and returns a Dispatching_Domain containing all the processors in the range +First .. Last. These processors are removed from System_Dispatching_Domain. A call of Create will raise +Dispatching_Domain_Error if any designated processor is not currently in System_Dispatching_Domain, +or if the system cannot support a distinct domain over the processors identified, or if a processor has a task +assigned to it, or if the allocation would leave System_Dispatching_Domain empty. A call of Create will +raise Dispatching_Domain_Error if the calling task is not the environment task, or if Create is called after +the call to the main subprogram. + +24/3 + +The function Get_First_CPU returns the first CPU in Domain; Get_Last_CPU returns the last one. + +25/3 + +The function Get_Dispatching_Domain returns the Dispatching_Domain on which the task is assigned. + +26/3 + +27/3 + +28/3 + +29/3 + +A call of the procedure Assign_Task assigns task T to the CPU within Dispatching_Domain Domain. Task +T can now execute only on CPU unless CPU designates Not_A_Specific_CPU, in which case it can +execute on any processor within Domain. The exception Dispatching_Domain_Error is propagated if T is +already assigned to a Dispatching_Domain other than System_Dispatching_Domain, or if CPU is not one +of the processors of Domain (and is not Not_A_Specific_CPU). A call of Assign_Task is a task +dispatching point for task T unless T is inside of a protected action, in which case the effect on task T is +delayed until its next task dispatching point. If T is the Current_Task the effect is immediate if T is not +inside a protected action, otherwise the effect is as soon as practical. Assigning a task to +System_Dispatching_Domain that is already assigned to that domain has no effect. + +A call of procedure Set_CPU assigns task T to the CPU. Task T can now execute only on CPU, unless +CPU designates Not_A_Specific_CPU, in which case it can execute on any processor within its +Dispatching_Domain. The exception Dispatching_Domain_Error is propagated if CPU is not one of the +processors of the Dispatching_Domain on which T is assigned (and is not Not_A_Specific_CPU). A call +of Set_CPU is a task dispatching point for task T unless T is inside of a protected action, in which case the +effect on task T is delayed until its next task dispatching point. If T is the Current_Task the effect is +immediate if T is not inside a protected action, otherwise the effect is as soon as practical. + +The function Get_CPU returns the processor assigned to task T, or Not_A_Specific_CPU if the task is not +assigned to a processor. + +A call of Delay_Until_And_Set_CPU delays the calling task for the designated time and then assigns the +task to the specified processor when the delay expires. The exception Dispatching_Domain_Error is +propagated if P is not one of the processors of the calling task's Dispatching_Domain (and is not +Not_A_Specific_CPU). + +D.16.1 Multiprocessor Dispatching Domains + +13 December 2012 668 + + Ada Reference Manual — 2012 Edition + +Implementation Requirements + +implementation + +The +Delay_Until_And_Set_CPU atomically with respect +dispatching_domain, processor or task. + +shall perform + +the operations Assign_Task, Set_CPU, Get_CPU and +the same + +these operations on + +to any of + +Each dispatching domain should have separate and disjoint ready queues. + +Implementation Advice + +The implementation shall document the processor(s) on which the clock interrupt is handled and hence +where delay queue and ready queue manipulations occur. For any Interrupt_Id whose handler can execute +on more than one processor the implementation shall also document this set of processors. + +Documentation Requirements + +30/3 + +31/3 + +32/3 + +An implementation may limit the number of dispatching domains that can be created and raise +Dispatching_Domain_Error if an attempt is made to exceed this number. + +33/3 + +Implementation Permissions + +669 13 December 2012 + +Multiprocessor Dispatching Domains D.16.1 + + Ada Reference Manual — 2012 Edition + +Annex E +(normative) +Distributed Systems + +This Annex defines facilities for supporting the implementation of distributed systems using multiple +partitions working cooperatively as part of a single Ada program. + +Post-Compilation Rules + +A distributed system is an interconnection of one or more processing nodes (a system resource that has +both computational and storage capabilities), and zero or more storage nodes (a system resource that has +only storage capabilities, with the storage addressable by one or more processing nodes). + +A distributed program comprises one or more partitions that execute independently (except when they +communicate) in a distributed system. + +The process of mapping the partitions of a program to the nodes in a distributed system is called +configuring the partitions of the program. + +The implementation shall provide means for explicitly assigning library units to a partition and for the +configuring and execution of a program consisting of multiple partitions on a distributed system; the +means are implementation defined. + +Implementation Requirements + +Implementation Permissions + +An implementation may require that the set of processing nodes of a distributed system be homogeneous. + +NOTES +1 The partitions comprising a program may be executed on differently configured distributed systems or on a +nondistributed system without requiring recompilation. A distributed program may be partitioned differently from the +same set of library units without recompilation. The resulting execution is semantically equivalent. + +2 A distributed program retains the same type safety as the equivalent single partition program. + +E.1 Partitions + +The partitions of a distributed program are classified as either active or passive. + +Post-Compilation Rules + +An active partition is a partition as defined in 10.2. A passive partition is a partition that has no thread of +control of its own, whose library units are all preelaborated, and whose data and subprograms are +accessible to one or more active partitions. + +A passive partition shall include only library_items that either are declared pure or are shared passive (see +10.2.1 and E.2.1). + +An active partition shall be configured on a processing node. A passive partition shall be configured either +on a storage node or on a processing node. + +The configuration of the partitions of a program onto a distributed system shall be consistent with the +possibility for data references or calls between the partitions implied by their semantic dependences. Any +reference to data or call of a subprogram across partitions is called a remote access. + +1 + +2 + +3 + +4 + +5 + +6 + +7 + +8 + +1 + +2 + +3 + +4 + +5 + +671 13 December 2012 + +Distributed Systems E + + Ada Reference Manual — 2012 Edition + +Dynamic Semantics + +6 + +7 + +A library_item is elaborated as part of the elaboration of each partition that includes it. If a normal library +unit (see E.2) has state, then a separate copy of the state exists in each active partition that elaborates it. +The state evolves independently in each such partition. + +An active partition terminates when its environment task terminates. A partition becomes inaccessible if it +terminates or if it is aborted. An active partition is aborted when its environment task is aborted. In +addition, if a partition fails during its elaboration, it becomes inaccessible to other partitions. Other +implementation-defined events can also result in a partition becoming inaccessible. + +8/1 + +For a prefix D that denotes a library-level declaration, excepting a declaration of or within a declared-pure +library unit, the following attribute is defined: + +9 + +D'Partition_Id + +Denotes a value of the type universal_integer that identifies the partition in which D was +elaborated. If D denotes the declaration of a remote call interface library unit (see E.2.3) the +given partition is the one where the body of D was elaborated. + +10/2 + +It is a bounded error for there to be cyclic elaboration dependences between the active partitions of a +single distributed program. The possible effects, in each of the partitions involved, are deadlock during +elaboration, or the raising of Communication_Error or Program_Error. + +Bounded (Run-Time) Errors + +Implementation Permissions + +11 + +12 + +13 + +14 + +15 + +16 + +An implementation may allow multiple active or passive partitions to be configured on a single processing +node, and multiple passive partitions to be configured on a single storage node. In these cases, the +scheduling policies, treatment of priorities, and management of shared resources between these partitions +are implementation defined. + +An implementation may allow separate copies of an active partition to be configured on different +processing nodes, and to provide appropriate interactions between the copies to present a consistent state +of the partition to other active partitions. + +In an implementation, the partitions of a distributed program need not be loaded and elaborated all at the +same time; they may be loaded and elaborated one at a time over an extended period of time. An +implementation may provide facilities to abort and reload a partition during the execution of a distributed +program. + +An implementation may allow the state of some of the partitions of a distributed program to persist while +other partitions of the program terminate and are later reinvoked. + +NOTES +3 Library units are grouped into partitions after compile time, but before run time. At compile time, only the relevant +library unit properties are identified using categorization pragmas. + +4 The value returned by the Partition_Id attribute can be used as a parameter to implementation-provided subprograms in +order to query information about the partition. + +E.1 Partitions + +13 December 2012 672 + + + Ada Reference Manual — 2012 Edition + +E.2 Categorization of Library Units + +Library units can be categorized according to the role they play in a distributed program. Certain +restrictions are associated with each category to ensure that the semantics of a distributed program remain +close to the semantics for a nondistributed program. + +A categorization pragma is a library unit pragma (see 10.1.5) that specifies a corresponding categorization +aspect. A categorization aspect restricts the declarations, child units, or semantic dependences of the +library unit to which it applies. A categorized library unit is a library unit that has a categorization aspect +that is True. + +The pragmas Shared_Passive, Remote_Types, and Remote_Call_Interface are categorization pragmas, and +the associated aspects are categorization aspects. In addition, for the purposes of this Annex, the aspect +Pure (see 10.2.1) is considered a categorization aspect and the pragma Pure is considered a categorization +pragma. + +A library package or generic library package is called a shared passive library unit if the Shared_Passive +aspect of the unit is True. A library package or generic library package is called a remote types library +unit if the Remote_Types aspect of the unit is True. A library unit is called a remote call interface if the +Remote_Call_Interface aspect of the unit is True. A normal library unit is one for which no categorization +aspect is True. + +The various categories of library units and the associated restrictions are described in this and the +following subclauses. The categories are related hierarchically in that the library units of one category can +depend semantically only on library units of that category or an earlier one in the hierarchy, except that the +body of a remote types or remote call interface library unit is unrestricted, the declaration of a remote +types or remote call interface library unit may depend on preelaborated normal library units that are +mentioned only in private with clauses, and all categories can depend on limited views. + +The overall hierarchy (including declared pure) is as follows, with a lower-numbered category being +“earlier in the hierarchy” in the sense of the previous paragraph: + +1. Declared Pure + +2. Shared Passive + +3. Remote Types + +4. Remote Call Interface + +5. Normal (no restrictions) + +Paragraphs 7 through 11 were deleted. + +1 + +2/3 + +3/3 + +4/3 + +5/3 + +6/3 + +6.1/3 + +6.2/3 + +6.3/3 + +6.4/3 + +6.5/3 + +Declared pure and shared passive library units are preelaborated. The declaration of a remote types or +remote call interface library unit is required to be preelaborable. + +12 + +Paragraph 13 was deleted. + +Implementations are allowed to define other categorization pragmas. + +14 + +Implementation Permissions + +673 13 December 2012 + +Categorization of Library Units E.2 + + Ada Reference Manual — 2012 Edition + +E.2.1 Shared Passive Library Units + +A shared passive library unit is used for managing global data shared between active partitions. The +restrictions on shared passive library units prevent the data or tasks of one active partition from being +accessible to another active partition through references implicit in objects declared in the shared passive +library unit. + +The form of a pragma Shared_Passive is as follows: + pragma Shared_Passive[(library_unit_name)]; + +Syntax + +Legality Rules + +A pragma Shared_Passive is used to specify that a library unit is a shared passive library unit, namely that +the Shared_Passive aspect of the library unit is True. The following restrictions apply to such a library +unit: +• +• +• + +it shall not contain a library-level declaration of an access type that designates a class-wide type, +task type, or protected type with entry_declarations. + +it shall depend semantically only upon declared pure or shared passive library_items; + +it shall be preelaborable (see 10.2.1); + +Notwithstanding the definition of accessibility given in 3.10.2, the declaration of a library unit P1 is not +accessible from within the declarative region of a shared passive library unit P2, unless the shared passive +library unit P2 depends semantically on P1. + +1 + +2 + +3 + +4/3 + +5 + +6/3 + +7/1 + +8 + +9 + +A shared passive library unit is preelaborated. + +Static Semantics + +10 + +11 + +1 + +2 + +3 + +4/3 + +Post-Compilation Rules + +A shared passive library unit shall be assigned to at most one partition within a given program. + +Notwithstanding the rule given in 10.2, a compilation unit in a given partition does not need (in the sense +of 10.2) the shared passive library units on which it depends semantically to be included in that same +partition; they will typically reside in separate passive partitions. + +E.2.2 Remote Types Library Units + +A remote types library unit supports the definition of types intended for use in communication between +active partitions. + +The form of a pragma Remote_Types is as follows: + pragma Remote_Types[(library_unit_name)]; + +Syntax + +Legality Rules + +A pragma Remote_Types is used to specify that a library unit is a remote types library unit, namely that +the Remote_Types aspect of the library unit is True. The following restrictions apply to the declaration of +such a library unit: + +5 + +• + +it shall be preelaborable; + +E.2.1 Shared Passive Library Units + +13 December 2012 674 + + Ada Reference Manual — 2012 Edition + +• + +• +• + +it shall depend semantically only on declared pure library_items, shared passive library units, +other remote types library units, or preelaborated normal library units that are mentioned only in +private with clauses; + +it shall not contain the declaration of any variable within the visible part of the library unit; + +the full view of each type declared in the visible part of the library unit that has any available +stream attributes shall support external streaming (see 13.13.2). + +A named access type declared in the visible part of a remote types or remote call interface library unit is +called a remote access type. Such a type shall be: + +• an access-to-subprogram type, or +• a general access type that designates a class-wide limited private type, a class-wide limited +interface type, or a class-wide private extension all of whose ancestors are either private +extensions, limited interface types, or limited private types. + +A type that is derived from a remote access type is also a remote access type. + +The following restrictions apply to the use of a remote access-to-subprogram type: + +• A value of a remote access-to-subprogram type shall be converted only to or from another + +(subtype-conformant) remote access-to-subprogram type; + +• The prefix of an Access attribute_reference that yields a value of a remote access-to- + +subprogram type shall statically denote a (subtype-conformant) remote subprogram. + +The following restrictions apply to the use of a remote access-to-class-wide type: + +• The primitive subprograms of the corresponding specific type shall only have access parameters +if they are controlling formal parameters. The primitive functions of the corresponding specific +type shall only have an access result if it is a controlling access result. Each noncontrolling +formal parameter and noncontrolling result type shall support external streaming (see 13.13.2); +• The corresponding specific type shall not have a primitive procedure with the Synchronization + +aspect specified unless the synchronization_kind is Optional (see 9.5); + +• A value of a remote access-to-class-wide type shall be explicitly converted only to another + +remote access-to-class-wide type; + +• A value of a remote access-to-class-wide type shall be dereferenced (or implicitly converted to +an anonymous access type) only as part of a dispatching call where the value designates a +controlling operand of the call (see E.4, “Remote Subprogram Calls”); + +• A controlling access result value for a primitive function with any controlling operands of the +corresponding specific type shall either be explicitly converted to a remote access-to-class-wide +type or be part of a dispatching call where the value designates a controlling operand of the call; +• The Storage_Pool attribute is not defined for a remote access-to-class-wide type; the expected +type for an allocator shall not be a remote access-to-class-wide type. A remote access-to-class- +wide type shall not be an actual parameter for a generic formal access type. The Storage_Size +attribute of a remote access-to-class-wide +in an +attribute_definition_clause. + +is not allowed + +type yields 0; + +it + +6/3 + +7 + +8/2 + +9/3 + +9.1/1 + +9.2/3 + +9.3/1 + +10 + +11/2 + +12 + +13 + +14/3 + +14.1/3 + +15 + +16 + +16.1/3 + +17/2 + +NOTES +5 A remote types library unit need not be pure, and the types it defines may include levels of indirection implemented by +using access types. User-specified Read and Write attributes (see 13.13.2) provide for sending values of such a type +between active partitions, with Write marshalling the representation, and Read unmarshalling any levels of indirection. + +18 + +6 The value of a remote access-to-class-wide limited interface can designate an object of a nonlimited type derived from +the interface. + +19/3 + +675 13 December 2012 + +Remote Types Library Units E.2.2 + + Ada Reference Manual — 2012 Edition + +20/3 + +7 A remote access type may designate a class-wide synchronized, protected, or task interface type. + +1 + +2 + +3 + +4 + +5 + +6 + +7/3 + +8/3 + +E.2.3 Remote Call Interface Library Units + +A remote call interface library unit can be used as an interface for remote procedure calls (RPCs) (or +remote function calls) between active partitions. + +Syntax + +The form of a pragma Remote_Call_Interface is as follows: + pragma Remote_Call_Interface[(library_unit_name)]; + +The form of a pragma All_Calls_Remote is as follows: + pragma All_Calls_Remote[(library_unit_name)]; + +A pragma All_Calls_Remote is a library unit pragma. + +Legality Rules + +A pragma Remote_Call_Interface is used to specify that a library unit is a remote call interface (RCI), +namely that the Remote_Call_Interface aspect of the library unit is True. A subprogram declared in the +visible part of such a library unit, or declared by such a library unit, is called a remote subprogram. + +The declaration of an RCI library unit shall be preelaborable (see 10.2.1), and shall depend semantically +only upon declared pure library_items, shared passive library units, remote types library units, other +remote call interface library units, or preelaborated normal library units that are mentioned only in private +with clauses. + +9/1 + +In addition, the following restrictions apply to an RCI library unit: + +10/1 + +11/1 + +12/1 + +13/3 + +14/3 + +15 + +16/3 + +17 + +18 + +• +• +• +• + +• + +its visible part shall not contain the declaration of a variable; + +its visible part shall not contain the declaration of a limited type; + +its visible part shall not contain a nested generic_declaration; + +it shall not be, nor shall its visible part contain, the declaration of a subprogram for which aspect +Inline is True; + +it shall not be, nor shall its visible part contain, a subprogram (or access-to-subprogram) +declaration whose profile has a parameter or result of a type that does not support external +streaming (see 13.13.2); + +• any public child of the library unit shall be a remote call interface library unit. + +A pragma All_Calls_Remote sets the All_Calls_Remote representation aspect of the library unit to which +the pragma applies to the value True. If the All_Calls_Remote aspect of a library unit is True, the library +unit shall be a remote call interface. + +Post-Compilation Rules + +A remote call interface library unit shall be assigned to at most one partition of a given program. A remote +call interface library unit whose parent is also an RCI library unit shall be assigned only to the same +partition as its parent. + +Notwithstanding the rule given in 10.2, a compilation unit in a given partition that semantically depends +on the declaration of an RCI library unit, needs (in the sense of 10.2) only the declaration of the RCI +library unit, not the body, to be included in that same partition. Therefore, the body of an RCI library unit +is included only in the partition to which the RCI library unit is explicitly assigned. + +E.2.2 Remote Types Library Units + +13 December 2012 676 + + Ada Reference Manual — 2012 Edition + +Implementation Requirements + +If aspect All_Calls_Remote is True for a given RCI library unit, then the implementation shall route any +call to a subprogram of the RCI unit from outside the declarative region of the unit through the Partition +Communication Subsystem (PCS); see E.5. Calls to such subprograms from within the declarative region +of the unit are defined to be local and shall not go through the PCS. + +Implementation Permissions + +implementation need not support + +the +An +All_Calls_Remote pragma. Explicit message-based communication between active partitions can be +supported as an alternative to RPC. + +the Remote_Call_Interface pragma or aspect nor + +19/3 + +20/3 + +E.3 Consistency of a Distributed System + +This subclause defines attributes and rules associated with verifying the consistency of a distributed +program. + +1/3 + +Static Semantics + +For a prefix P that statically denotes a program unit, the following attributes are defined: + +P'Version + +Yields a value of the predefined type String that identifies the version of the compilation +unit that contains the declaration of the program unit. + +P'Body_Version + +Yields a value of the predefined type String that identifies the version of the compilation +unit that contains the body (but not any subunits) of the program unit. + +The version of a compilation unit changes whenever the compilation unit changes in a semantically +significant way. This International Standard does not define the exact meaning of "semantically +significant". It is unspecified whether there are other events (such as recompilation) that result in the +version of a compilation unit changing. + +2/1 + +3 + +4 + +5/1 + +If P is not a library unit, and P has no completion, then P'Body_Version returns the Body_Version of the +innermost program unit enclosing the declaration of P. If P is a library unit, and P has no completion, then +P'Body_Version returns a value that is different from Body_Version of any version of P that has a +completion. + +5.1/1 + +Bounded (Run-Time) Errors + +In a distributed program, a library unit is consistent if the same version of its declaration is used +throughout. It is a bounded error to elaborate a partition of a distributed program that contains a +compilation unit that depends on a different version of the declaration of a shared passive or RCI library +unit than that included in the partition to which the shared passive or RCI library unit was assigned. As a +result of this error, Program_Error can be raised in one or both partitions during elaboration; in any case, +the partitions become inaccessible to one another. + +E.4 Remote Subprogram Calls + +A remote subprogram call is a subprogram call that invokes the execution of a subprogram in another +partition. The partition that originates the remote subprogram call is the calling partition, and the partition +that executes the corresponding subprogram body is the called partition. Some remote procedure calls are + +6 + +1 + +677 13 December 2012 + +Remote Call Interface Library Units E.2.3 + + + Ada Reference Manual — 2012 Edition + +allowed to return prior to the completion of subprogram execution. These are called asynchronous remote +procedure calls. + +2 + +3 + +4 + +5 + +6 + +There are three different ways of performing a remote subprogram call: + +• As a direct call on a (remote) subprogram explicitly declared in a remote call interface; +• As an indirect call through a value of a remote access-to-subprogram type; +• As a dispatching call with a controlling operand designated by a value of a remote access-to- + +class-wide type. + +The first way of calling corresponds to a static binding between the calling and the called partition. The +latter two ways correspond to a dynamic binding between the calling and the called partition. + +7/3 + +Remote types library units (see E.2.2) and remote call interface library units (see E.2.3) define the remote +subprograms or remote access types used for remote subprogram calls. + +8 + +9 + +10 + +11 + +12 + +13 + +14 + +15 + +In a dispatching call with two or more controlling operands, if one controlling operand is designated by a +value of a remote access-to-class-wide type, then all shall be. + +Legality Rules + +Dynamic Semantics + +For the execution of a remote subprogram call, subprogram parameters (and later the results, if any) are +passed using a stream-oriented representation (see 13.13.1) which is suitable for transmission between +partitions. This action is called marshalling. Unmarshalling is the reverse action of reconstructing the +parameters or results from the stream-oriented representation. Marshalling is performed initially as part of +the remote subprogram call in the calling partition; unmarshalling is done in the called partition. After the +remote subprogram completes, marshalling is performed in the called partition, and finally unmarshalling +is done in the calling partition. + +A calling stub is the sequence of code that replaces the subprogram body of a remotely called subprogram +in the calling partition. A receiving stub is the sequence of code (the “wrapper”) that receives a remote +subprogram call on the called partition and invokes the appropriate subprogram body. + +Remote subprogram calls are executed at most once, that is, if the subprogram call returns normally, then +the called subprogram's body was executed exactly once. + +The task executing a remote subprogram call blocks until the subprogram in the called partition returns, +unless the call is asynchronous. For an asynchronous remote procedure call, the calling task can become +ready before the procedure in the called partition returns. + +If a construct containing a remote call is aborted, the remote subprogram call is cancelled. Whether the +execution of the remote subprogram is immediately aborted as a result of the cancellation is implemen- +tation defined. + +If a remote subprogram call is received by a called partition before the partition has completed its +elaboration, the call is kept pending until the called partition completes its elaboration (unless the call is +cancelled by the calling partition prior to that). + +If an exception is propagated by a remotely called subprogram, and the call is not an asynchronous call, +the corresponding exception is reraised at the point of the remote subprogram call. For an asynchronous +call, if the remote procedure call returns prior to the completion of the remotely called subprogram, any +exception is lost. + +E.4 Remote Subprogram Calls + +13 December 2012 678 + + Ada Reference Manual — 2012 Edition + +The exception Communication_Error (see E.5) is raised if a remote call cannot be completed due to +difficulties in communicating with the called partition. + +All forms of remote subprogram calls are potentially blocking operations (see 9.5.1). + +In a remote subprogram call with a formal parameter of a class-wide type, a check is made that the tag of +the actual parameter identifies a tagged type declared in a declared-pure or shared passive library unit, or +in the visible part of a remote types or remote call interface library unit. Program_Error is raised if this +check fails. In a remote function call which returns a class-wide type, the same check is made on the +function result. + +In a dispatching call with two or more controlling operands that are designated by values of a remote +access-to-class-wide type, a check is made (in addition to the normal Tag_Check — see 11.5) that all the +remote access-to-class-wide values originated from Access attribute_references that were evaluated by +tasks of the same active partition. Constraint_Error is raised if this check fails. + +Implementation Requirements + +The implementation of remote subprogram calls shall conform to the PCS interface as defined by the +specification of the language-defined package System.RPC (see E.5). The calling stub shall use the +Do_RPC procedure unless the remote procedure call is asynchronous in which case Do_APC shall be +used. On the receiving side, the corresponding receiving stub shall be invoked by the RPC-receiver. + +16 + +17 + +18/1 + +19 + +20 + +With respect to shared variables in shared passive library units, the execution of the corresponding +subprogram body of a synchronous remote procedure call is considered to be part of the execution of the +calling task. The execution of the corresponding subprogram body of an asynchronous remote procedure +call proceeds in parallel with the calling task and does not signal the next action of the calling task (see +9.10). + +20.1/1 + +NOTES +8 A given active partition can both make and receive remote subprogram calls. Thus, an active partition can act as both a +client and a server. + +9 If a given exception is propagated by a remote subprogram call, but the exception does not exist in the calling partition, +the exception can be handled by an others choice or be propagated to and handled by a third partition. + +21 + +22 + +E.4.1 Asynchronous Remote Calls + +This subclause introduces the aspect Asynchronous which can be specified to allow a remote subprogram +call to return prior to completion of the execution of the corresponding remote subprogram body. + +1/3 + +Paragraphs 2 through 7 were deleted. + +Static Semantics + +For a remote procedure, the following language-defined representation aspect may be specified: + +8/3 + +Asynchronous The type of aspect Asynchronous is Boolean. If directly specified, the aspect_definition + +8.1/3 + +shall be a static expression. If not specified, the aspect is False. + +For a remote access type, the following language-defined representation aspect may be specified: + +8.2/3 + +Asynchronous The type of aspect Asynchronous is Boolean. If directly specified, the aspect_definition + +8.3/3 + +shall be a static expression. If not specified (including by inheritance), the aspect is False. + +679 13 December 2012 + +Remote Subprogram Calls E.4 + + Ada Reference Manual — 2012 Edition + +8.4/3 + +8.5/3 + +9/3 + +Legality Rules + +If aspect Asynchronous is specified for a remote procedure, the formal parameters of the procedure shall +all be of mode in. + +If aspect Asynchronous is specified for a remote access type, the type shall be a remote access-to-class- +wide type, or the type shall be a remote access-to-procedure type with the formal parameters of the +designated profile of the type all of mode in. + +Dynamic Semantics + +A remote call is asynchronous if it is a call to a procedure, or a call through a value of an access-to- +procedure type, for which aspect Asynchronous is True. In addition, if aspect Asynchronous is True for a +remote access-to-class-wide type, then a dispatching call on a procedure with a controlling operand +designated by a value of the type is asynchronous if the formal parameters of the procedure are all of mode +in. + +10 + +Asynchronous remote procedure calls shall be implemented such that the corresponding body executes at +most once as a result of the call. + +Implementation Requirements + +E.4.2 Example of Use of a Remote Access-to-Class-Wide Type + +Example of using a remote access-to-class-wide type to achieve dynamic binding across active partitions: + +Examples + +package Tapes is + pragma Pure(Tapes); + type Tape is abstract tagged limited private; + -- Primitive dispatching operations where + -- Tape is controlling operand + procedure Copy (From, To : access Tape; Num_Recs : in Natural) is +abstract; + procedure Rewind (T : access Tape) is abstract; + -- More operations +private + type Tape is ... +end Tapes; +with Tapes; +package Name_Server is + pragma Remote_Call_Interface; + -- Dynamic binding to remote operations is achieved + -- using the access-to-limited-class-wide type Tape_Ptr + type Tape_Ptr is access all Tapes.Tape'Class; + -- The following statically bound remote operations + -- allow for a name-server capability in this example + function Find (Name : String) return Tape_Ptr; + procedure Register (Name : in String; T : in Tape_Ptr); + procedure Remove (T : in Tape_Ptr); + -- More operations +end Name_Server; +package Tape_Driver is + -- Declarations are not shown, they are irrelevant here +end Tape_Driver; + +1 + +2 + +3 + +4 + +E.4.1 Asynchronous Remote Calls + +13 December 2012 680 + + Ada Reference Manual — 2012 Edition + +with Tapes, Name_Server; +package body Tape_Driver is + type New_Tape is new Tapes.Tape with ... + procedure Copy + (From, To : access New_Tape; Num_Recs: in Natural) is + begin + . . . + end Copy; + procedure Rewind (T : access New_Tape) is + begin + . . . + end Rewind; + -- Objects remotely accessible through use + -- of Name_Server operations + Tape1, Tape2 : aliased New_Tape; +begin + Name_Server.Register ("NINE-TRACK", Tape1'Access); + Name_Server.Register ("SEVEN-TRACK", Tape2'Access); +end Tape_Driver; +with Tapes, Name_Server; +-- Tape_Driver is not needed and thus not mentioned in the with_clause +procedure Tape_Client is + T1, T2 : Name_Server.Tape_Ptr; +begin + T1 := Name_Server.Find ("NINE-TRACK"); + T2 := Name_Server.Find ("SEVEN-TRACK"); + Tapes.Rewind (T1); + Tapes.Rewind (T2); + Tapes.Copy (T1, T2, 3); +end Tape_Client; + +Notes on the example: + +This paragraph was deleted. + +• The package Tapes provides the necessary declarations of the type and its primitive operations. +• Name_Server is a remote call interface package and is elaborated in a separate active partition to +provide the necessary naming services (such as Register and Find) to the entire distributed +program through remote subprogram calls. + +• Tape_Driver is a normal package that is elaborated in a partition configured on the processing +node that is connected to the tape device(s). The abstract operations are overridden to support +the locally declared tape devices (Tape1, Tape2). The package is not visible to its clients, but it +exports the tape devices (as remote objects) through the services of the Name_Server. This +allows for tape devices to be dynamically added, removed or replaced without requiring the +modification of the clients' code. + +• The Tape_Client procedure references only declarations in the Tapes and Name_Server +packages. Before using a tape for the first time, it needs to query the Name_Server for a system- +wide identity for that tape. From then on, it can use that identity to access the tape device. + +• Values of remote access type Tape_Ptr include the necessary information to complete the remote + +dispatching operations that result from dereferencing the controlling operands T1 and T2. + +5 + +6 + +7 + +8/1 + +9 + +10 + +11 + +12 + +13 + +681 13 December 2012 + +Example of Use of a Remote Access-to-Class-Wide Type E.4.2 + + Ada Reference Manual — 2012 Edition + +E.5 Partition Communication Subsystem + +1/2 + +The Partition Communication Subsystem (PCS) provides facilities for supporting communication between +the active partitions of a distributed program. The package System.RPC is a language-defined interface to +the PCS. + +2 + +3 + +4 + +5 + +6 + +7 + +8 + +9 + +10 + +11 + +12 + +13 + +14 + +15 + +16 + +17 + +The following language-defined library package exists: + +Static Semantics + +with Ada.Streams; -- see 13.13.1 +package System.RPC is + type Partition_Id is range 0 .. implementation-defined; + Communication_Error : exception; + type Params_Stream_Type ( + Initial_Size : Ada.Streams.Stream_Element_Count) is new + Ada.Streams.Root_Stream_Type with private; + procedure Read( + Stream : in out Params_Stream_Type; + Item : out Ada.Streams.Stream_Element_Array; + Last : out Ada.Streams.Stream_Element_Offset); + procedure Write( + Stream : in out Params_Stream_Type; + Item : in Ada.Streams.Stream_Element_Array); + -- Synchronous call + procedure Do_RPC( + Partition : in Partition_Id; + Params : access Params_Stream_Type; + Result : access Params_Stream_Type); + -- Asynchronous call + procedure Do_APC( + Partition : in Partition_Id; + Params : access Params_Stream_Type); + -- The handler for incoming RPCs + type RPC_Receiver is access procedure( + Params : access Params_Stream_Type; + Result : access Params_Stream_Type); + procedure Establish_RPC_Receiver( + Partition : in Partition_Id; + Receiver : in RPC_Receiver); +private + ... -- not specified by the language +end System.RPC; + +A value of the type Partition_Id is used to identify a partition. + +An object of the type Params_Stream_Type is used for identifying the particular remote subprogram that is +being called, as well as marshalling and unmarshalling the parameters or result of a remote subprogram +call, as part of sending them between partitions. + +The Read and Write procedures override the corresponding abstract operations for the type +Params_Stream_Type. + +The Do_RPC and Do_APC procedures send a message to the active partition identified by the Partition +parameter. + +Dynamic Semantics + +E.5 Partition Communication Subsystem + +13 December 2012 682 + + Ada Reference Manual — 2012 Edition + +After sending the message, Do_RPC blocks the calling task until a reply message comes back from the +called partition or some error is detected by the underlying communication system in which case +Communication_Error is raised at the point of the call to Do_RPC. + +Do_APC operates in the same way as Do_RPC except that it is allowed to return immediately after +sending the message. + +Upon normal return, the stream designated by the Result parameter of Do_RPC contains the reply +message. + +The procedure System.RPC.Establish_RPC_Receiver is called once, immediately after elaborating the +library units of an active partition (that is, right after the elaboration of the partition) if the partition +includes an RCI library unit, but prior to invoking the main subprogram, if any. The Partition parameter is +the Partition_Id of the active partition being elaborated. The Receiver parameter designates an +implementation-provided procedure called the RPC-receiver which will handle all RPCs received by the +partition from the PCS. Establish_RPC_Receiver saves a reference to the RPC-receiver; when a message +is received at the called partition, the RPC-receiver is called with the Params stream containing the +message. When the RPC-receiver returns, the contents of the stream designated by Result is placed in a +message and sent back to the calling partition. + +If a call on Do_RPC is aborted, a cancellation message is sent to the called partition, to request that the +execution of the remotely called subprogram be aborted. + +The subprograms declared in System.RPC are potentially blocking operations. + +The implementation of the RPC-receiver shall be reentrant, thereby allowing concurrent calls on it from +the PCS to service concurrent remote subprogram calls into the partition. + +Implementation Requirements + +18 + +19 + +20 + +21 + +22 + +23 + +24 + +An implementation shall not restrict the replacement of the body of System.RPC. An implementation shall +not restrict children of System.RPC. The related implementation permissions in the introduction to Annex +A do not apply. + +24.1/1 + +If the implementation of System.RPC is provided by the user, an implementation shall support remote +subprogram calls as specified. + +24.2/1 + +The implementation of the PCS shall document whether the RPC-receiver is invoked from concurrent +tasks. If there is an upper limit on the number of such tasks, this limit shall be documented as well, +together with the mechanisms to configure it (if this is supported). + +Documentation Requirements + +Implementation Permissions + +The PCS is allowed to contain implementation-defined interfaces for explicit message passing, +broadcasting, etc. Similarly, it is allowed to provide additional interfaces to query the state of some remote +partition (given its partition ID) or of the PCS itself, to set timeouts and retry parameters, to get more +detailed error status, etc. These additional interfaces should be provided in child packages of System.RPC. + +A body for the package System.RPC need not be supplied by the implementation. + +An alternative declaration is allowed for package System.RPC as long as it provides a set of operations +that is substantially equivalent to the specification defined in this subclause. + +25 + +26 + +27 + +27.1/3 + +683 13 December 2012 + +Partition Communication Subsystem E.5 + + Ada Reference Manual — 2012 Edition + +Implementation Advice + +28 + +29 + +30 + +Whenever possible, the PCS on the called partition should allow for multiple tasks to call the RPC- +receiver with different messages and should allow them to block until the corresponding subprogram body +returns. + +The Write operation on a stream of type Params_Stream_Type should raise Storage_Error if it runs out of +space trying to write the Item into the stream. + +NOTES +10 The package System.RPC is not designed for direct calls by user programs. It is instead designed for use in the +implementation of remote subprograms calls, being called by the calling stubs generated for a remote call interface library +unit to initiate a remote call, and in turn calling back to an RPC-receiver that dispatches to the receiving stubs generated +for the body of a remote call interface, to handle a remote call received from elsewhere. + +E.5 Partition Communication Subsystem + +13 December 2012 684 + + Ada Reference Manual — 2012 Edition + +Annex F +(normative) +Information Systems + +This Annex provides a set of facilities relevant to Information Systems programming. These fall into +several categories: + +• an attribute definition clause specifying Machine_Radix for a decimal subtype; +• + +the package Decimal, which declares a set of constants defining the implementation's capacity +for decimal types, and a generic procedure for decimal division; and + +• + +the child packages Text_IO.Editing, Wide_Text_IO.Editing, and Wide_Wide_Text_IO.Editing, +which support formatted and localized output of decimal data, based on “picture String” values. + +See also: 3.5.9, “Fixed Point Types”; 3.5.10, “Operations of Fixed Point Types”; 4.6, “Type Conversions”; +13.3, “Operational and Representation Attributes”; A.10.9, “Input-Output for Real Types”; B.3, +“Interfacing with C and C++”; B.4, “Interfacing with COBOL”; Annex G, “Numerics”. + +1 + +2 + +3 + +4/2 + +5/2 + +The character and string handling packages in Annex A, “Predefined Language Environment” are also +relevant for Information Systems. + +6 + +Implementation Advice + +If COBOL (respectively, C) is widely supported in the target environment, implementations supporting the +Information Systems Annex should provide the child package Interfaces.COBOL (respectively, +Interfaces.C) specified in Annex B and should support a convention_identifier of COBOL (respectively, C) +for the Convention aspect (see Annex B), thus allowing Ada programs to interface with programs written +in that language. + +7/3 + +F.1 Machine_Radix Attribute Definition Clause + +Machine_Radix may be specified for a decimal first subtype (see 3.5.9) via an attribute_definition_clause; +the expression of such a clause shall be static, and its value shall be 2 or 10. A value of 2 implies a binary +base range; a value of 10 implies a decimal base range. + +Static Semantics + +Packed decimal should be used as the internal representation for objects of subtype S when +S'Machine_Radix = 10. + +Implementation Advice + +Example of Machine_Radix attribute definition clause: +type Money is delta 0.01 digits 15; +for Money'Machine_Radix use 10; + +Examples + +1 + +2 + +3 + +4 + +685 13 December 2012 + +Information Systems F + + Ada Reference Manual — 2012 Edition + +F.2 The Package Decimal + +The library package Decimal has the following declaration: + +Static Semantics + +package Ada.Decimal is + pragma Pure(Decimal); + Max_Scale : constant := implementation-defined; + Min_Scale : constant := implementation-defined; + Min_Delta : constant := 10.0**(-Max_Scale); + Max_Delta : constant := 10.0**(-Min_Scale); + Max_Decimal_Digits : constant := implementation-defined; + generic + type Dividend_Type is delta <> digits <>; + type Divisor_Type is delta <> digits <>; + type Quotient_Type is delta <> digits <>; + type Remainder_Type is delta <> digits <>; + procedure Divide (Dividend : in Dividend_Type; + Divisor : in Divisor_Type; + Quotient : out Quotient_Type; + Remainder : out Remainder_Type) + with Convention => Intrinsic; +end Ada.Decimal; + +Max_Scale is the largest N such that 10.0**(–N) is allowed as a decimal type's delta. Its type is +universal_integer. + +Min_Scale is the smallest N such that 10.0**(–N) is allowed as a decimal type's delta. Its type is +universal_integer. + +Min_Delta is the smallest value allowed for delta in a decimal_fixed_point_definition. Its type is +universal_real. + +Max_Delta is the largest value allowed for delta in a decimal_fixed_point_definition. Its type is +universal_real. + +Max_Decimal_Digits is the largest value allowed for digits in a decimal_fixed_point_definition. Its type is +universal_integer. + +The effect of Divide is as follows. The value of Quotient is Quotient_Type(Dividend/Divisor). The value +of Remainder is Remainder_Type(Intermediate), where Intermediate is the difference between Dividend +and the product of Divisor and Quotient; this result is computed exactly. + +Static Semantics + +Implementation Requirements + +Decimal.Max_Decimal_Digits shall be at least 18. + +Decimal.Max_Scale shall be at least 18. + +Decimal.Min_Scale shall be at most 0. + +NOTES +1 The effect of division yielding a quotient with control over rounding versus truncation is obtained by applying either +the function attribute Quotient_Type'Round or the conversion Quotient_Type to the expression Dividend/Divisor. + +F.2 The Package Decimal + +13 December 2012 686 + +1 + +2 + +3 + +4 + +5 + +6/3 + +7 + +8 + +9 + +10 + +11 + +12 + +13 + +14 + +15 + +16 + +17 + + Ada Reference Manual — 2012 Edition + +F.3 Edited Output for Decimal Types + +The child packages Text_IO.Editing, Wide_Text_IO.Editing, and Wide_Wide_Text_IO.Editing provide +localizable formatted text output, known as edited output, for decimal types. An edited output string is a +function of a numeric value, program-specifiable locale elements, and a format control value. The numeric +value is of some decimal type. The locale elements are: + +• +• +• +• + +the currency string; + +the digits group separator character; + +the radix mark character; and + +the fill character that replaces leading zeros of the numeric value. + +For Text_IO.Editing the edited output and currency strings are of type String, and the locale characters are +of type Character. For Wide_Text_IO.Editing their types are Wide_String and Wide_Character, +respectively. For Wide_Wide_Text_IO.Editing their types are Wide_Wide_String and Wide_Wide_- +Character, respectively. + +Each of the locale elements has a default value that can be replaced or explicitly overridden. + +A format-control value is of the private type Picture; it determines the composition of the edited output +string and controls the form and placement of the sign, the position of the locale elements and the decimal +digits, the presence or absence of a radix mark, suppression of leading zeros, and insertion of particular +character values. + +A Picture object is composed from a String value, known as a picture String, that serves as a template for +the edited output string, and a Boolean value that controls whether a string of all space characters is +produced when the number's value is zero. A picture String comprises a sequence of one- or two-Character +symbols, each serving as a placeholder for a character or string at a corresponding position in the edited +output string. The picture String symbols fall into several categories based on their effect on the edited +output string: + +Decimal Digit: +Radix Control: +Sign Control: +Currency Control: +Zero Suppression: +Simple Insertion: + +'9' +'.' +'+' +'$' +'Z' +'_' + +'V' +'–' +'#' +'*' +'B' + +'<' + +'>' + +"CR" + +"DB" + +'0' + +'/' + +The entries are not case-sensitive. Mixed- or lower-case forms for "CR" and "DB", and lower-case forms +for 'V', 'Z', and 'B', have the same effect as the upper-case symbols shown. + +An occurrence of a '9' Character in the picture String represents a decimal digit position in the edited +output string. + +A radix control Character in the picture String indicates the position of the radix mark in the edited output +string: an actual character position for '.', or an assumed position for 'V'. + +A sign control Character in the picture String affects the form of the sign in the edited output string. The +'<' and '>' Character values indicate parentheses for negative values. A Character '+', '–', or '<' appears +either singly, signifying a fixed-position sign in the edited output, or repeated, signifying a floating- +position sign that is preceded by zero or more space characters and that replaces a leading 0. + +1/2 + +2 + +3 + +4 + +5 + +6/2 + +7 + +8 + +9 + +10 + +11 + +12 + +13 + +14 + +687 13 December 2012 + +Edited Output for Decimal Types F.3 + + + + + + + + Ada Reference Manual — 2012 Edition + +A currency control Character in the picture String indicates an occurrence of the currency string in the +edited output string. The '$' Character represents the complete currency string; the '#' Character represents +one character of the currency string. A '$' Character appears either singly, indicating a fixed-position +currency string in the edited output, or repeated, indicating a floating-position currency string that occurs +in place of a leading 0. A sequence of '#' Character values indicates either a fixed- or floating-position +currency string, depending on context. + +A zero suppression Character in the picture String allows a leading zero to be replaced by either the space +character (for 'Z') or the fill character (for '*'). + +A simple insertion Character in the picture String represents, in general, either itself (if '/' or '0'), the space +character (if 'B'), or the digits group separator character (if '_'). In some contexts it is treated as part of a +floating sign, floating currency, or zero suppression string. + +An example of a picture String is "<###Z_ZZ9.99>". If the currency string is "kr", the separator character +is ',', and the radix mark is '.' then the edited output string values for the decimal values 32.10 and – +5432.10 are "bbkrbbb32.10b" and "(bkr5,432.10)", respectively, where 'b' indicates the space character. + +generic + +and +The +Wide_Wide_Text_IO.Decimal_IO (see A.10.9, “Input-Output for Real Types”) provide text input and +nonedited text output for decimal types. + +Wide_Text_IO.Decimal_IO, + +Text_IO.Decimal_IO, + +packages + +NOTES +2 A picture String +is of +Wide_Wide_Text_IO.Editing. + +type Standard.String, + +for all of Text_IO.Editing, Wide_Text_IO.Editing, and + +15 + +16 + +17 + +18/2 + +19/2 + +20/2 + +F.3.1 Picture String Formation + +1/3 + +A well-formed picture String, or simply picture String, is a String value that conforms to the syntactic +rules, composition constraints, and character replication conventions specified in this subclause. + +Dynamic Semantics + +2/1 + +This paragraph was deleted. + +3 + +picture_string ::= + fixed_$_picture_string + | fixed_#_picture_string + | floating_currency_picture_string + | non_currency_picture_string + +F.3 Edited Output for Decimal Types + +13 December 2012 688 + + + Ada Reference Manual — 2012 Edition + +fixed_$_picture_string ::= + [fixed_LHS_sign] fixed_$_char {direct_insertion} [zero_suppression] + number [RHS_sign] + + | [fixed_LHS_sign {direct_insertion}] [zero_suppression] + number fixed_$_char {direct_insertion} [RHS_sign] + + | floating_LHS_sign number fixed_$_char {direct_insertion} [RHS_sign] + + | [fixed_LHS_sign] fixed_$_char {direct_insertion} + all_zero_suppression_number {direct_insertion} [RHS_sign] + + | [fixed_LHS_sign {direct_insertion}] all_zero_suppression_number {direct_insertion} + fixed_$_char {direct_insertion} [RHS_sign] + + | all_sign_number {direct_insertion} fixed_$_char {direct_insertion} [RHS_sign] + +fixed_#_picture_string ::= + [fixed_LHS_sign] single_#_currency {direct_insertion} + [zero_suppression] number [RHS_sign] + + | [fixed_LHS_sign] multiple_#_currency {direct_insertion} + zero_suppression number [RHS_sign] + + | [fixed_LHS_sign {direct_insertion}] [zero_suppression] + number fixed_#_currency {direct_insertion} [RHS_sign] + + | floating_LHS_sign number fixed_#_currency {direct_insertion} [RHS_sign] + + | [fixed_LHS_sign] single_#_currency {direct_insertion} + all_zero_suppression_number {direct_insertion} [RHS_sign] + + | [fixed_LHS_sign] multiple_#_currency {direct_insertion} + all_zero_suppression_number {direct_insertion} [RHS_sign] + + | [fixed_LHS_sign {direct_insertion}] all_zero_suppression_number {direct_insertion} + fixed_#_currency {direct_insertion} [RHS_sign] + + | all_sign_number {direct_insertion} fixed_#_currency {direct_insertion} [RHS_sign] + +floating_currency_picture_string ::= + [fixed_LHS_sign] {direct_insertion} floating_$_currency number [RHS_sign] + | [fixed_LHS_sign] {direct_insertion} floating_#_currency number [RHS_sign] + | [fixed_LHS_sign] {direct_insertion} all_currency_number {direct_insertion} [RHS_sign] + +4 + +5 + +6 + +689 13 December 2012 + +Picture String Formation F.3.1 + + + + + + + + + + + + + + + + + 7 + +8 + +9 + +10 + +11 + +12 + +13 + +14 + +15 + +16 + +17 + +18 + +19 + +20 + +21 + +22 + +23 + +24 + +25 + +26 + +27 + +Ada Reference Manual — 2012 Edition + +non_currency_picture_string ::= + [fixed_LHS_sign {direct_insertion}] zero_suppression number [RHS_sign] + | [floating_LHS_sign] number [RHS_sign] + | [fixed_LHS_sign {direct_insertion}] all_zero_suppression_number {direct_insertion} + [RHS_sign] + | all_sign_number {direct_insertion} + | fixed_LHS_sign direct_insertion {direct_insertion} number [RHS_sign] + +fixed_LHS_sign ::= LHS_Sign + +LHS_Sign ::= + | – | < + +fixed_$_char ::= $ + +direct_insertion ::= simple_insertion + +simple_insertion ::= _ | B | 0 | / + +zero_suppression ::= Z {Z | context_sensitive_insertion} | fill_string + +context_sensitive_insertion ::= simple_insertion + +fill_string ::= * {* | context_sensitive_insertion} + +number ::= + fore_digits [radix [aft_digits] {direct_insertion}] + | radix aft_digits {direct_insertion} + +fore_digits ::= 9 {9 | direct_insertion} + +aft_digits ::= {9 | direct_insertion} 9 + +radix ::= . | V + +RHS_sign ::= + | – | > | CR | DB + +floating_LHS_sign ::= + LHS_Sign {context_sensitive_insertion} LHS_Sign {LHS_Sign | context_sensitive_insertion} + +single_#_currency ::= # + +multiple_#_currency ::= ## {#} + +fixed_#_currency ::= single_#_currency | multiple_#_currency + +floating_$_currency ::= + $ {context_sensitive_insertion} $ {$ | context_sensitive_insertion} + +floating_#_currency ::= + # {context_sensitive_insertion} # {# | context_sensitive_insertion} + +all_sign_number ::= all_sign_fore [radix [all_sign_aft]] [>] + +F.3.1 Picture String Formation + +13 December 2012 690 + + + + + + + + + + + + + + + all_sign_fore ::= + sign_char {context_sensitive_insertion} sign_char {sign_char | context_sensitive_insertion} + +Ada Reference Manual — 2012 Edition + +all_sign_aft ::= {all_sign_aft_char} sign_char + +all_sign_aft_char ::= sign_char | context_sensitive_insertion + +sign_char ::= + | – | < + +all_currency_number ::= all_currency_fore [radix [all_currency_aft]] + +all_currency_fore ::= + currency_char {context_sensitive_insertion} + currency_char {currency_char | context_sensitive_insertion} + +all_currency_aft ::= {all_currency_aft_char} currency_char + +all_currency_aft_char ::= currency_char | context_sensitive_insertion + +currency_char ::= $ | # + +all_zero_suppression_number ::= all_zero_suppression_fore [ radix [all_zero_suppression_aft]] + +all_zero_suppression_fore ::= + zero_suppression_char {zero_suppression_char | context_sensitive_insertion} + +all_zero_suppression_aft ::= {all_zero_suppression_aft_char} zero_suppression_char + +all_zero_suppression_aft_char ::= zero_suppression_char | context_sensitive_insertion + +zero_suppression_char ::= Z | * + +The following composition constraints apply to a picture String: + +• A floating_LHS_sign does not have occurrences of different LHS_Sign Character values. +• If a picture String has '<' as fixed_LHS_sign, then it has '>' as RHS_sign. +• If a picture String has '<' in a floating_LHS_sign or in an all_sign_number, then it has an + +occurrence of '>'. + +28 + +29 + +30 + +31 + +32 + +33 + +34 + +35 + +36 + +37 + +38 + +39 + +40 + +41 + +42 + +• If a picture String has '+' or '–' as fixed_LHS_sign, in a floating_LHS_sign, or in an + +43/1 + +all_sign_number, then it has no RHS_sign or '>' character. + +• An instance of all_sign_number does not have occurrences of different sign_char Character + +values. + +• An instance of all_currency_number does not have occurrences of different currency_char + +Character values. + +• An instance of all_zero_suppression_number does not have occurrences of different zero_- +suppression_char Character values, except for possible case differences between 'Z' and 'z'. + +A replicable Character is a Character that, by the above rules, can occur in two consecutive positions in a +picture String. + +A Character replication is a String + +char & '(' & spaces & count_string & ')' + +where char is a replicable Character, spaces is a String (possibly empty) comprising only space Character +values, and count_string is a String of one or more decimal digit Character values. A Character replication + +44 + +45 + +46 + +47 + +48 + +49 + +50 + +691 13 December 2012 + +Picture String Formation F.3.1 + + + + + + + Ada Reference Manual — 2012 Edition + +in a picture String has the same effect as (and is said to be equivalent to) a String comprising n consecutive +occurrences of char, where n=Integer'Value(count_string). + +51 + +An expanded picture String is a picture String containing no Character replications. + +52 + +NOTES +3 Although a sign to the left of the number can float, a sign to the right of the number is in a fixed position. + +1 + +2 + +3 + +4 + +5 + +6 + +7 + +8 + +9 + +10 + +11 + +12 + +13 + +14 + +15 + +16 + +17 + +18 + +F.3.2 Edited Output Generation + +The contents of an edited output string are based on: + +Dynamic Semantics + +• A value, Item, of some decimal type Num, +• An expanded picture String Pic_String, +• A Boolean value, Blank_When_Zero, +• A Currency string, +• A Fill character, +• A Separator character, and +• A Radix_Mark character. + +The combination of a True value for Blank_When_Zero and a '*' character in Pic_String is inconsistent; no +edited output string is defined. + +A layout error is identified in the rules below if leading nonzero digits of Item, character values of the +Currency string, or a negative sign would be truncated; in such cases no edited output string is defined. + +The edited output string has lower bound 1 and upper bound N where N = Pic_String'Length + +Currency_Length_Adjustment – Radix_Adjustment, and + +• Currency_Length_Adjustment = Currency'Length – 1 if there is some occurrence of '$' in + +Pic_String, and 0 otherwise. + +• Radix_Adjustment = 1 if there is an occurrence of 'V' or 'v' in Pic_Str, and 0 otherwise. + +Let the magnitude of Item be expressed as a base-10 number Ip···I1.F1···Fq, called the displayed magnitude +of Item, where: + +• q = Min(Max(Num'Scale, 0), n) where n is 0 if Pic_String has no radix and is otherwise the +number of digit positions following radix in Pic_String, where a digit position corresponds to an +occurrence of +'9', a zero_suppression_char (for an all_zero_suppression_number), a +currency_char (for an all_currency_number), or a sign_char (for an all_sign_number). + +• Ip /= 0 if p>0. + +If n < Num'Scale, then the above number is the result of rounding (away from 0 if exactly midway +between values). + +If Blank_When_Zero = True and the displayed magnitude of Item is zero, then the edited output string +comprises all space character values. Otherwise, the picture String is treated as a sequence of instances of +syntactic categories based on the rules in F.3.1, and the edited output string is the concatenation of string +values derived from these categories according to the following mapping rules. + +F.3.1 Picture String Formation + +13 December 2012 692 + + Ada Reference Manual — 2012 Edition + +Table F-1 shows the mapping from a sign control symbol to a corresponding character or string in the +edited output. In the columns showing the edited output, a lower-case 'b' represents the space character. If +there is no sign control symbol but the value of Item is negative, a layout error occurs and no edited output +string is produced. + +19 + + Table F-1: Edited Output for Sign Control Symbols +Edited Output for +Nonnegative +Number + + Sign Control +Symbol + +Edited Output for +Negative Number + + '+' + '–' + '<' + '>' + "CR" + "DB" + +'+' + +'b' + +'b' + +'b' + +"bb" + +"bb" + +'–' + +'–' + +'(' + +')' + +"CR" + +"DB" + +An instance of fixed_LHS_sign maps to a character as shown in Table F-1. + +An instance of fixed_$_char maps to Currency. + +An instance of direct_insertion maps to Separator if direct_insertion = '_', and to the direct_insertion +Character otherwise. + +An instance of number maps to a string integer_part & radix_part & fraction_part where: + +• The string for integer_part is obtained as follows: + +1. Occurrences of '9' in fore_digits of number are replaced from right to left with the decimal + +digit character values for I1, ..., Ip, respectively. + +2. Each occurrence of '9' in fore_digits to the left of the leftmost '9' replaced according to rule + +1 is replaced with '0'. + +3. If p exceeds the number of occurrences of '9' in fore_digits of number, then the excess +leftmost digits are eligible for use in the mapping of an instance of zero_suppression, +floating_LHS_sign, floating_$_currency, or floating_#_currency to the left of number; if +there is no such instance, then a layout error occurs and no edited output string is produced. + +• The radix_part is: + +• "" if number does not include a radix, if radix = 'V', or if radix = 'v' + +• Radix_Mark if number includes '.' as radix +• The string for fraction_part is obtained as follows: + +1. Occurrences of '9' in aft_digits of number are replaced from left to right with the decimal + +digit character values for F1, ... Fq. + +2. Each occurrence of '9' in aft_digits to the right of the rightmost '9' replaced according to + +rule 1 is replaced by '0'. + +An instance of zero_suppression maps to the string obtained as follows: + +20 + +21 + +22 + +23 + +24 + +25 + +26 + +27 + +28 + +29 + +30 + +31 + +32 + +33 + +34 + +693 13 December 2012 + +Edited Output Generation F.3.2 + + + + Ada Reference Manual — 2012 Edition + +35 + +36 + +37 + +38 + +39 + +40 + +41 + +42 + +43 + +44 + +45 + +46 + +47 + +48 + +49 + +50 + +51 + +52 + +53 + +54 + +1. The rightmost 'Z', 'z', or '*' Character values are replaced with the excess digits (if any) from the + +integer_part of the mapping of the number to the right of the zero_suppression instance, + +2. A context_sensitive_insertion Character is replaced as though it were a direct_insertion +Character, if it occurs to the right of some 'Z', 'z', or '*' in zero_suppression that has been +mapped to an excess digit, + +3. Each Character to the left of the leftmost Character replaced according to rule 1 above is + +replaced by: + +• + +• + +the space character if the zero suppression Character is 'Z' or 'z', or + +the Fill character if the zero suppression Character is '*'. + +4. A layout error occurs if some excess digits remain after all 'Z', 'z', and '*' Character values in + +zero_suppression have been replaced via rule 1; no edited output string is produced. + +An instance of RHS_sign maps to a character or string as shown in Table F-1. + +An instance of floating_LHS_sign maps to the string obtained as follows. + +1. Up to all but one of the rightmost LHS_Sign Character values are replaced by the excess digits +(if any) from the integer_part of the mapping of the number to the right of the +floating_LHS_sign instance. + +2. The next Character to the left is replaced with the character given by the entry in Table F-1 + +corresponding to the LHS_Sign Character. + +3. A context_sensitive_insertion Character is replaced as though it were a direct_insertion +Character, if it occurs to the right of the leftmost LHS_Sign character replaced according to rule +1. + +4. Any other Character is replaced by the space character.. + +5. A layout error occurs if some excess digits remain after replacement via rule 1; no edited output + +string is produced. + +An instance of fixed_#_currency maps to the Currency string with n space character values concatenated +on the left (if the instance does not follow a radix) or on the right (if the instance does follow a radix), +where n is the difference between the length of the fixed_#_currency instance and Currency'Length. A +layout error occurs if Currency'Length exceeds the length of the fixed_#_currency instance; no edited +output string is produced. + +An instance of floating_$_currency maps to the string obtained as follows: + +1. Up to all but one of the rightmost '$' Character values are replaced with the excess digits (if any) +from the integer_part of the mapping of the number to the right of the floating_$_currency +instance. + +2. The next Character to the left is replaced by the Currency string. + +3. A context_sensitive_insertion Character is replaced as though it were a direct_insertion + +Character, if it occurs to the right of the leftmost '$' Character replaced via rule 1. + +4. Each other Character is replaced by the space character. + +5. A layout error occurs if some excess digits remain after replacement by rule 1; no edited output + +string is produced. + +55 + +An instance of floating_#_currency maps to the string obtained as follows: + +F.3.2 Edited Output Generation + +13 December 2012 694 + + Ada Reference Manual — 2012 Edition + +1. Up to all but one of the rightmost '#' Character values are replaced with the excess digits (if any) +from the integer_part of the mapping of the number to the right of the floating_#_currency +instance. + +2. The substring whose last Character occurs at the position immediately preceding the leftmost +Character replaced via rule 1, and whose length is Currency'Length, is replaced by the Currency +string. + +3. A context_sensitive_insertion Character is replaced as though it were a direct_insertion + +Character, if it occurs to the right of the leftmost '#' replaced via rule 1. + +4. Any other Character is replaced by the space character. + +5. A layout error occurs if some excess digits remain after replacement rule 1, or if there is no +substring with the required length for replacement rule 2; no edited output string is produced. + +An instance of all_zero_suppression_number maps to: + +• a string of all spaces if the displayed magnitude of Item is zero, the zero_suppression_char is +'Z' or 'z', and the instance of all_zero_suppression_number does not have a radix at its last +character position; + +• a string containing the Fill character in each position except for the character (if any) +corresponding to radix, if zero_suppression_char = '*' and the displayed magnitude of Item is +zero; + +• otherwise, the same result as if each zero_suppression_char in all_zero_suppression_aft were +'9', interpreting the instance of all_zero_suppression_number as either zero_suppression +number (if a radix and all_zero_suppression_aft are present), or as zero_suppression +otherwise. + +An instance of all_sign_number maps to: + +• a string of all spaces if the displayed magnitude of Item is zero and the instance of + +all_sign_number does not have a radix at its last character position; + +• otherwise, the same result as if each sign_char in all_sign_number_aft were '9', interpreting the +radix and + +instance of all_sign_number as either +all_sign_number_aft are present), or as floating_LHS_sign otherwise. + +floating_LHS_sign number (if a + +An instance of all_currency_number maps to: + +• a string of all spaces if the displayed magnitude of Item is zero and the instance of + +all_currency_number does not have a radix at its last character position; + +• otherwise, the same result as if each currency_char in all_currency_number_aft were '9', +interpreting +floating_$_currency number or +floating_#_currency number (if a radix and all_currency_number_aft are present), or as +floating_$_currency or floating_#_currency otherwise. + +instance of all_currency_number as + +the + +In the result string values shown below, 'b' represents the space character. + +Examples + +Item: Picture and Result Strings: + +123456.78 Picture: "-###**_***_**9.99" + Result: "bbb$***123,456.78" + "bbFF***123.456,78" (currency = "FF", + separator = '.', + radix mark = ',') + +695 13 December 2012 + +Edited Output Generation F.3.2 + +56 + +57 + +58 + +59 + +60 + +61 + +62 + +63 + +64 + +65 + +66 + +67 + +68 + +69 + +70 + +71 + +72 + +73/3 + + Ada Reference Manual — 2012 Edition + +74/1 + +123456.78 Picture: "-$**_***_**9.99" + Result: "b$***123,456.78" + "bFF***123.456,78" (currency = "FF", + separator = '.', + radix mark = ',') + +75 + +76 + +77 + +78 + +1 + +2 + +3 + +4 + +5 + +6 + +7 + +8 + +9 + +10 + +11 + +12 + +0.0 Picture: "-$$$$$$.$$" + Result: "bbbbbbbbbb" + +0.20 Picture: "-$$$$$$.$$" + Result: "bbbbbb$.20" + +-1234.565 Picture: "<<<<_<<<.<<###>" + Result: "bb(1,234.57DMb)" (currency = "DM") + +12345.67 Picture: "###_###_##9.99" + Result: "bbCHF12,345.67" (currency = "CHF") + +F.3.3 The Package Text_IO.Editing + +The package Text_IO.Editing provides a private type Picture with associated operations, and a generic +package Decimal_Output. An object of type Picture is composed from a well-formed picture String (see +F.3.1) and a Boolean item indicating whether a zero numeric value will result in an edited output string of +all space characters. The package Decimal_Output contains edited output subprograms implementing the +effects defined in F.3.2. + +The library package Text_IO.Editing has the following declaration: + +Static Semantics + +package Ada.Text_IO.Editing is + type Picture is private; + function Valid (Pic_String : in String; + Blank_When_Zero : in Boolean := False) return Boolean; + function To_Picture (Pic_String : in String; + Blank_When_Zero : in Boolean := False) + return Picture; + function Pic_String (Pic : in Picture) return String; + function Blank_When_Zero (Pic : in Picture) return Boolean; + Max_Picture_Length : constant := implementation_defined; + Picture_Error : exception; + Default_Currency : constant String := "$"; + Default_Fill : constant Character := '*'; + Default_Separator : constant Character := ','; + Default_Radix_Mark : constant Character := '.'; + generic + type Num is delta <> digits <>; + Default_Currency : in String := Text_IO.Editing.Default_Currency; + Default_Fill : in Character := Text_IO.Editing.Default_Fill; + Default_Separator : in Character := + Text_IO.Editing.Default_Separator; + Default_Radix_Mark : in Character := + Text_IO.Editing.Default_Radix_Mark; + package Decimal_Output is + function Length (Pic : in Picture; + Currency : in String := Default_Currency) + return Natural; + function Valid (Item : in Num; + Pic : in Picture; + Currency : in String := Default_Currency) + return Boolean; + +F.3.2 Edited Output Generation + +13 December 2012 696 + + Ada Reference Manual — 2012 Edition + + function Image (Item : in Num; + Pic : in Picture; + Currency : in String := Default_Currency; + Fill : in Character := Default_Fill; + Separator : in Character := Default_Separator; + Radix_Mark : in Character := Default_Radix_Mark) + return String; + procedure Put (File : in File_Type; + Item : in Num; + Pic : in Picture; + Currency : in String := Default_Currency; + Fill : in Character := Default_Fill; + Separator : in Character := Default_Separator; + Radix_Mark : in Character := Default_Radix_Mark); + procedure Put (Item : in Num; + Pic : in Picture; + Currency : in String := Default_Currency; + Fill : in Character := Default_Fill; + Separator : in Character := Default_Separator; + Radix_Mark : in Character := Default_Radix_Mark); + procedure Put (To : out String; + Item : in Num; + Pic : in Picture; + Currency : in String := Default_Currency; + Fill : in Character := Default_Fill; + Separator : in Character := Default_Separator; + Radix_Mark : in Character := Default_Radix_Mark); + end Decimal_Output; +private + ... -- not specified by the language +end Ada.Text_IO.Editing; + +The exception Constraint_Error is raised if the Image function or any of the Put procedures is invoked +with a null string for Currency. + +function Valid (Pic_String : in String; + Blank_When_Zero : in Boolean := False) return Boolean; + +Valid returns True if Pic_String is a well-formed picture String (see F.3.1) the length of whose +expansion does not exceed Max_Picture_Length, and if either Blank_When_Zero is False or +Pic_String contains no '*'. + +function To_Picture (Pic_String : in String; + Blank_When_Zero : in Boolean := False) + return Picture; + +To_Picture returns a result Picture such that the application of the function Pic_String to this +result yields an expanded picture String equivalent +that +Blank_When_Zero applied to the result Picture is the same value as the parameter +Blank_When_Zero. Picture_Error is raised if not Valid(Pic_String, Blank_When_Zero). + +to Pic_String, and such + +function Pic_String (Pic : in Picture) return String; + +function Blank_When_Zero (Pic : in Picture) return Boolean; + +If Pic is To_Picture(String_Item, Boolean_Item) for some String_Item and Boolean_Item, then: +• Pic_String(Pic) returns an expanded picture String equivalent to String_Item and with + +any lower-case letter replaced with its corresponding upper-case form, and + +• Blank_When_Zero(Pic) returns Boolean_Item. + +If Pic_1 and Pic_2 are objects of type Picture, then "="(Pic_1, Pic_2) is True when + +697 13 December 2012 + +The Package Text_IO.Editing F.3.3 + +13 + +14 + +15 + +16 + +17 + +18 + +19 + +20 + +21 + +22 + +23 + +24 + +25 + +26 + + + 27 + +28 + +29 + +30 + +31 + +32 + +33 + +34 + +35 + +36 + +37 + +38 + +39 + +40 + +41 + +42 + +Ada Reference Manual — 2012 Edition + +• Pic_String(Pic_1) = Pic_String(Pic_2), and +• Blank_When_Zero(Pic_1) = Blank_When_Zero(Pic_2). + +function Length (Pic : in Picture; + Currency : in String := Default_Currency) + return Natural; + +Length returns Pic_String(Pic)'Length + Currency_Length_Adjustment – Radix_Adjustment +where + +• Currency_Length_Adjustment = + +• Currency'Length – 1 if there is some occurrence of '$' in Pic_String(Pic), and + +• 0 otherwise. +• Radix_Adjustment = + +• 1 if there is an occurrence of 'V' or 'v' in Pic_Str(Pic), and + +• 0 otherwise. + +function Valid (Item : in Num; + Pic : in Picture; + Currency : in String := Default_Currency) + return Boolean; + +Valid returns True if Image(Item, Pic, Currency) does not raise Layout_Error, and returns False +otherwise. + +function Image (Item : in Num; + Pic : in Picture; + Currency : in String := Default_Currency; + Fill : in Character := Default_Fill; + Separator : in Character := Default_Separator; + Radix_Mark : in Character := Default_Radix_Mark) + return String; + +Image returns the edited output String as defined in F.3.2 for Item, Pic_String(Pic), +Blank_When_Zero(Pic), Currency, Fill, Separator, and Radix_Mark. If these rules identify a +layout error, then Image raises the exception Layout_Error. + +procedure Put (File : in File_Type; + Item : in Num; + Pic : in Picture; + Currency : in String := Default_Currency; + Fill : in Character := Default_Fill; + Separator : in Character := Default_Separator; + Radix_Mark : in Character := Default_Radix_Mark); + +procedure Put (Item : in Num; + Pic : in Picture; + Currency : in String := Default_Currency; + Fill : in Character := Default_Fill; + Separator : in Character := Default_Separator; + Radix_Mark : in Character := Default_Radix_Mark); + +Each of these Put procedures outputs Image(Item, Pic, Currency, Fill, Separator, Radix_Mark) +consistent with the conventions for Put for other real types in case of bounded line length (see +A.10.6, “Get and Put Procedures”). + +F.3.3 The Package Text_IO.Editing + +13 December 2012 698 + + + Ada Reference Manual — 2012 Edition + +procedure Put (To : out String; + Item : in Num; + Pic : in Picture; + Currency : in String := Default_Currency; + Fill : in Character := Default_Fill; + Separator : in Character := Default_Separator; + Radix_Mark : in Character := Default_Radix_Mark); + +43 + +Put copies Image(Item, Pic, Currency, Fill, Separator, Radix_Mark) to the given string, right +justified. Otherwise, unassigned Character values in To are assigned the space character. If +To'Length is less than the length of the string resulting from Image, then Layout_Error is raised. + +44/3 + +Max_Picture_Length shall be at least 30. The implementation shall support currency strings of length up +to at least 10, both for Default_Currency in an instantiation of Decimal_Output, and for Currency in an +invocation of Image or any of the Put procedures. + +Implementation Requirements + +NOTES +4 The rules for edited output are based on COBOL (ANSI X3.23:1985, endorsed by ISO as ISO 1989-1985), with the +following differences: + +• The COBOL provisions for picture string localization and for 'P' format are absent from Ada. +• The following Ada facilities are not in COBOL: + +• + +• + +• + +currency symbol placement after the number, + +localization of edited output string for multi-character currency string values, including support for both +length-preserving and length-expanding currency symbols in picture strings + +localization of the radix mark, digits separator, and fill character, and + +• parenthesization of negative values. + +The value of 30 for Max_Picture_Length is the same limit as in COBOL. + +F.3.4 The Package Wide_Text_IO.Editing + +Static Semantics + +The child package Wide_Text_IO.Editing has the same contents as Text_IO.Editing, except that: + +• each occurrence of Character is replaced by Wide_Character, +• each occurrence of Text_IO is replaced by Wide_Text_IO, +• +• each occurrence of String in the generic package Decimal_Output is replaced by Wide_String. + +the subtype of Default_Currency is Wide_String rather than String, and + +NOTES +5 Each of the functions Wide_Text_IO.Editing.Valid, To_Picture, and Pic_String has String (versus Wide_String) as its +parameter or result subtype, since a picture String is not localizable. + +F.3.5 The Package Wide_Wide_Text_IO.Editing + +The child package Wide_Wide_Text_IO.Editing has the same contents as Text_IO.Editing, except that: + +Static Semantics + +• each occurrence of Character is replaced by Wide_Wide_Character, +• each occurrence of Text_IO is replaced by Wide_Wide_Text_IO, +• + +the subtype of Default_Currency is Wide_Wide_String rather than String, and + +45 + +46 + +47 + +48 + +49 + +50 + +51 + +52 + +52.1 + +1 + +2 + +3 + +4 + +5 + +6 + +1/2 + +2/2 + +3/2 + +4/2 + +699 13 December 2012 + +The Package Text_IO.Editing F.3.3 + + Ada Reference Manual — 2012 Edition + +5/2 + +• each occurrence of String + +in + +the generic package Decimal_Output + +is replaced by + +Wide_Wide_String. + +6/2 + +NOTES +6 Each of +Wide_Wide_String) as its parameter or result subtype, since a picture String is not localizable. + +the functions Wide_Wide_Text_IO.Editing.Valid, To_Picture, and Pic_String has String (versus + +F.3.5 The Package Wide_Wide_Text_IO.Editing + +13 December 2012 700 + + Ada Reference Manual — 2012 Edition + +Annex G +(normative) +Numerics + +The Numerics Annex specifies + +• features for complex arithmetic, including complex I/O; +• a mode (“strict mode”), in which the predefined arithmetic operations of floating point and fixed +point types and the functions and operations of various predefined packages have to provide +guaranteed accuracy or conform to other numeric performance requirements, which the +Numerics Annex also specifies; + +• a mode (“relaxed mode”), in which no accuracy or other numeric performance requirements + +need be satisfied, as for implementations not conforming to the Numerics Annex; + +• models of floating point and fixed point arithmetic on which the accuracy requirements of strict + +mode are based; + +• + +the definitions of the model-oriented attributes of floating point types that apply in the strict +mode; and + +• features for the manipulation of real and complex vectors and matrices. + +Implementation Advice + +If Fortran (respectively, C) is widely supported in the target environment, implementations supporting the +Numerics Annex should provide the child package Interfaces.Fortran (respectively, Interfaces.C) specified +in Annex B and should support a convention_identifier of Fortran (respectively, C) for the Convention +aspect (see Annex B), thus allowing Ada programs to interface with programs written in that language. + +1 + +2 + +3 + +4 + +5/2 + +6/2 + +6.1/2 + +7/3 + +G.1 Complex Arithmetic + +Types and arithmetic operations for complex arithmetic are provided in Generic_Complex_Types, which +is defined in G.1.1. Implementation-defined approximations to the complex analogs of the mathematical +functions known as the “elementary functions” are provided by the subprograms in Generic_Complex_- +Elementary_Functions, which is defined in G.1.2. Both of these library units are generic children of the +predefined package Numerics (see A.5). Nongeneric equivalents of these generic packages for each of the +predefined floating point types are also provided as children of Numerics. + +1 + +G.1.1 Complex Types + +The generic library package Numerics.Generic_Complex_Types has the following declaration: + +Static Semantics + +generic + type Real is digits <>; +package Ada.Numerics.Generic_Complex_Types is + pragma Pure(Generic_Complex_Types); + type Complex is + record + Re, Im : Real'Base; + end record; + +1 + +2/1 + +3 + +701 13 December 2012 + +Numerics G + + Ada Reference Manual — 2012 Edition + +4/2 + +5 + +6 + +7 + +8 + +9 + +10 + +11 + +12 + +13 + +14 + +15 + +16 + +17 + +18 + +19 + + type Imaginary is private; + pragma Preelaborable_Initialization(Imaginary); + i : constant Imaginary; + j : constant Imaginary; + function Re (X : Complex) return Real'Base; + function Im (X : Complex) return Real'Base; + function Im (X : Imaginary) return Real'Base; + procedure Set_Re (X : in out Complex; + Re : in Real'Base); + procedure Set_Im (X : in out Complex; + Im : in Real'Base); + procedure Set_Im (X : out Imaginary; + Im : in Real'Base); + function Compose_From_Cartesian (Re, Im : Real'Base) return Complex; + function Compose_From_Cartesian (Re : Real'Base) return Complex; + function Compose_From_Cartesian (Im : Imaginary) return Complex; + function Modulus (X : Complex) return Real'Base; + function "abs" (Right : Complex) return Real'Base renames Modulus; + function Argument (X : Complex) return Real'Base; + function Argument (X : Complex; + Cycle : Real'Base) return Real'Base; + function Compose_From_Polar (Modulus, Argument : Real'Base) + return Complex; + function Compose_From_Polar (Modulus, Argument, Cycle : Real'Base) + return Complex; + function "+" (Right : Complex) return Complex; + function "-" (Right : Complex) return Complex; + function Conjugate (X : Complex) return Complex; + function "+" (Left, Right : Complex) return Complex; + function "-" (Left, Right : Complex) return Complex; + function "*" (Left, Right : Complex) return Complex; + function "/" (Left, Right : Complex) return Complex; + function "**" (Left : Complex; Right : Integer) return Complex; + function "+" (Right : Imaginary) return Imaginary; + function "-" (Right : Imaginary) return Imaginary; + function Conjugate (X : Imaginary) return Imaginary renames "-"; + function "abs" (Right : Imaginary) return Real'Base; + function "+" (Left, Right : Imaginary) return Imaginary; + function "-" (Left, Right : Imaginary) return Imaginary; + function "*" (Left, Right : Imaginary) return Real'Base; + function "/" (Left, Right : Imaginary) return Real'Base; + function "**" (Left : Imaginary; Right : Integer) return Complex; + function "<" (Left, Right : Imaginary) return Boolean; + function "<=" (Left, Right : Imaginary) return Boolean; + function ">" (Left, Right : Imaginary) return Boolean; + function ">=" (Left, Right : Imaginary) return Boolean; + function "+" (Left : Complex; Right : Real'Base) return Complex; + function "+" (Left : Real'Base; Right : Complex) return Complex; + function "-" (Left : Complex; Right : Real'Base) return Complex; + function "-" (Left : Real'Base; Right : Complex) return Complex; + function "*" (Left : Complex; Right : Real'Base) return Complex; + function "*" (Left : Real'Base; Right : Complex) return Complex; + function "/" (Left : Complex; Right : Real'Base) return Complex; + function "/" (Left : Real'Base; Right : Complex) return Complex; + +G.1.1 Complex Types + +13 December 2012 702 + + Ada Reference Manual — 2012 Edition + + function "+" (Left : Complex; Right : Imaginary) return Complex; + function "+" (Left : Imaginary; Right : Complex) return Complex; + function "-" (Left : Complex; Right : Imaginary) return Complex; + function "-" (Left : Imaginary; Right : Complex) return Complex; + function "*" (Left : Complex; Right : Imaginary) return Complex; + function "*" (Left : Imaginary; Right : Complex) return Complex; + function "/" (Left : Complex; Right : Imaginary) return Complex; + function "/" (Left : Imaginary; Right : Complex) return Complex; + function "+" (Left : Imaginary; Right : Real'Base) return Complex; + function "+" (Left : Real'Base; Right : Imaginary) return Complex; + function "-" (Left : Imaginary; Right : Real'Base) return Complex; + function "-" (Left : Real'Base; Right : Imaginary) return Complex; + function "*" (Left : Imaginary; Right : Real'Base) return Imaginary; + function "*" (Left : Real'Base; Right : Imaginary) return Imaginary; + function "/" (Left : Imaginary; Right : Real'Base) return Imaginary; + function "/" (Left : Real'Base; Right : Imaginary) return Imaginary; +private + type Imaginary is new Real'Base; + i : constant Imaginary := 1.0; + j : constant Imaginary := 1.0; +end Ada.Numerics.Generic_Complex_Types; + +The library package Numerics.Complex_Types is declared pure and defines the same types, constants, and +is +subprograms as Numerics.Generic_Complex_Types, except +systematically +of +Numerics.Generic_Complex_Types for each of the other predefined floating point types are defined +similarly, with the names Numerics.Short_Complex_Types, Numerics.Long_Complex_Types, etc. + +the predefined +Nongeneric + +type Float + +throughout. + +equivalents + +substituted + +Real'Base + +that + +for + +Complex is a visible type with Cartesian components. + +Imaginary is a private type; its full type is derived from Real'Base. + +The arithmetic operations and the Re, Im, Modulus, Argument, and Conjugate functions have their usual +mathematical meanings. When applied to a parameter of pure-imaginary type, the “imaginary-part” +function Im yields the value of its parameter, as the corresponding real value. The remaining subprograms +have the following meanings: + +• The Set_Re and Set_Im procedures replace the designated component of a complex parameter +with the given real value; applied to a parameter of pure-imaginary type, the Set_Im procedure +replaces the value of that parameter with the imaginary value corresponding to the given real +value. + +• The Compose_From_Cartesian function constructs a complex value from the given real and +imaginary components. If only one component is given, the other component is implicitly zero. +• The Compose_From_Polar function constructs a complex value from the given modulus (radius) +and argument (angle). When the value of the parameter Modulus is positive (resp., negative), the +result is the complex value represented by the point in the complex plane lying at a distance +from the origin given by the absolute value of Modulus and forming an angle measured +counterclockwise from the positive (resp., negative) real axis given by the value of the parameter +Argument. + +When the Cycle parameter is specified, the result of the Argument function and the parameter Argument +of the Compose_From_Polar function are measured in units such that a full cycle of revolution has the +given value; otherwise, they are measured in radians. + +The computed results of the mathematically multivalued functions are rendered single-valued by the +following conventions, which are meant to imply the principal branch: + +703 13 December 2012 + +Complex Types G.1.1 + +20 + +21 + +22 + +23 + +24 + +25/1 + +26/2 + +27 + +28 + +29 + +30 + +31 + +32 + +33 + + Ada Reference Manual — 2012 Edition + +34 + +35 + +36 + +37 + +38 + +39 + +40 + +41 + +42 + +43 + +44 + +45 + +46 + +47 + +48 + +49 + +50 + +• The result of the Modulus function is nonnegative. +• The result of the Argument function is in the quadrant containing the point in the complex plane +represented by the parameter X. This may be any quadrant (I through IV); thus, the range of the +Argument function is approximately –π to π (–Cycle/2.0 to Cycle/2.0, if the parameter Cycle is +specified). When the point represented by the parameter X lies on the negative real axis, the +result approximates + +• π (resp., –π) when the sign of the imaginary component of X is positive (resp., negative), if + +Real'Signed_Zeros is True; +• π, if Real'Signed_Zeros is False. + +• Because a result lying on or near one of the axes may not be exactly representable, the +approximation inherent in computing the result may place it in an adjacent quadrant, close to but +on the wrong side of the axis. + +Dynamic Semantics + +The exception Numerics.Argument_Error is raised by the Argument and Compose_From_Polar functions +with specified cycle, signaling a parameter value outside the domain of the corresponding mathematical +function, when the value of the parameter Cycle is zero or negative. + +The exception Constraint_Error is raised by the division operator when the value of the right operand is +zero, and by the exponentiation operator when the value of the left operand is zero and the value of the +exponent is negative, provided that Real'Machine_Overflows is True; when Real'Machine_Overflows is +False, the result is unspecified. Constraint_Error can also be raised when a finite result overflows (see +G.2.6). + +Implementation Requirements + +In the implementation of Numerics.Generic_Complex_Types, the range of intermediate values allowed +during the calculation of a final result shall not be affected by any range constraint of the subtype Real. + +In the following cases, evaluation of a complex arithmetic operation shall yield the prescribed result, +provided that the preceding rules do not call for an exception to be raised: + +• The results of the Re, Im, and Compose_From_Cartesian functions are exact. +• The real (resp., imaginary) component of the result of a binary addition operator that yields a +result of complex type is exact when either of its operands is of pure-imaginary (resp., real) type. +• The real (resp., imaginary) component of the result of a binary subtraction operator that yields a +result of complex type is exact when its right operand is of pure-imaginary (resp., real) type. + +• The real component of the result of the Conjugate function for the complex type is exact. +• When the point in the complex plane represented by the parameter X lies on the nonnegative real + +axis, the Argument function yields a result of zero. + +• When the value of the parameter Modulus is zero, the Compose_From_Polar function yields a + +result of zero. + +• When the value of the parameter Argument is equal to a multiple of the quarter cycle, the result +of the Compose_From_Polar function with specified cycle lies on one of the axes. In this case, +one of its components is zero, and the other has the magnitude of the parameter Modulus. + +• Exponentiation by a zero exponent yields the value one. Exponentiation by a unit exponent +yields the value of the left operand. Exponentiation of the value one yields the value one. +Exponentiation of the value zero yields the value zero, provided that the exponent is nonzero. + +G.1.1 Complex Types + +13 December 2012 704 + + Ada Reference Manual — 2012 Edition + +When the left operand is of pure-imaginary type, one component of the result of the +exponentiation operator is zero. + +When the result, or a result component, of any operator of Numerics.Generic_Complex_Types has a +mathematical definition in terms of a single arithmetic or relational operation, that result or result +component exhibits the accuracy of the corresponding operation of the type Real. + +Other accuracy requirements for the Modulus, Argument, and Compose_From_Polar functions, and +accuracy requirements for the multiplication of a pair of complex operands or for division by a complex +operand, all of which apply only in the strict mode, are given in G.2.6. + +The sign of a zero result or zero result component yielded by a complex arithmetic operation or function is +implementation defined when Real'Signed_Zeros is True. + +Implementation Permissions + +The nongeneric equivalent packages may, but need not, be actual instantiations of the generic package for +the appropriate predefined type. + +Implementations may obtain the result of exponentiation of a complex or pure-imaginary operand by +repeated complex multiplication, with arbitrary association of the factors and with a possible final complex +reciprocation (when the exponent is negative). Implementations are also permitted to obtain the result of +exponentiation of a complex operand, but not of a pure-imaginary operand, by converting the left operand +to a polar representation; exponentiating the modulus by the given exponent; multiplying the argument by +the given exponent; and reconverting to a Cartesian representation. Because of this implementation +freedom, no accuracy requirement is imposed on complex exponentiation (except for the prescribed results +given above, which apply regardless of the implementation method chosen). + +Implementation Advice + +Because the usual mathematical meaning of multiplication of a complex operand and a real operand is that +of the scaling of both components of the former by the latter, an implementation should not perform this +operation by first promoting the real operand to complex type and then performing a full complex +multiplication. In systems that, in the future, support an Ada binding to IEC 559:1989, the latter technique +will not generate the required result when one of the components of the complex operand is infinite. +(Explicit multiplication of the infinite component by the zero component obtained during promotion yields +a NaN that propagates into the final result.) Analogous advice applies in the case of multiplication of a +complex operand and a pure-imaginary operand, and in the case of division of a complex operand by a real +or pure-imaginary operand. + +Likewise, because the usual mathematical meaning of addition of a complex operand and a real operand is +that the imaginary operand remains unchanged, an implementation should not perform this operation by +first promoting the real operand to complex type and then performing a full complex addition. In +implementations in which the Signed_Zeros attribute of the component type is True (and which therefore +conform to IEC 559:1989 in regard to the handling of the sign of zero in predefined arithmetic operations), +the latter technique will not generate the required result when the imaginary component of the complex +operand is a negatively signed zero. (Explicit addition of the negative zero to the zero obtained during +promotion yields a positive zero.) Analogous advice applies in the case of addition of a complex operand +and a pure-imaginary operand, and in the case of subtraction of a complex operand and a real or pure- +imaginary operand. + +51 + +52 + +53 + +54 + +55/2 + +56 + +57 + +Implementations in which Real'Signed_Zeros is True should attempt to provide a rational treatment of the +signs of zero results and result components. As one example, the result of the Argument function should +have the sign of the imaginary component of the parameter X when the point represented by that + +58 + +705 13 December 2012 + +Complex Types G.1.1 + + Ada Reference Manual — 2012 Edition + +parameter lies on the positive real axis; as another, the sign of the imaginary component of the Compose_- +From_Polar function should be the same as (resp., the opposite of) that of the Argument parameter when +that parameter has a value of zero and the Modulus parameter has a nonnegative (resp., negative) value. + +G.1.2 Complex Elementary Functions + +Static Semantics + +The generic library package Numerics.Generic_Complex_Elementary_Functions has the following +declaration: + +with Ada.Numerics.Generic_Complex_Types; +generic + with package Complex_Types is + new Ada.Numerics.Generic_Complex_Types (<>); + use Complex_Types; +package Ada.Numerics.Generic_Complex_Elementary_Functions is + pragma Pure(Generic_Complex_Elementary_Functions); + function Sqrt (X : Complex) return Complex; + function Log (X : Complex) return Complex; + function Exp (X : Complex) return Complex; + function Exp (X : Imaginary) return Complex; + function "**" (Left : Complex; Right : Complex) return Complex; + function "**" (Left : Complex; Right : Real'Base) return Complex; + function "**" (Left : Real'Base; Right : Complex) return Complex; + function Sin (X : Complex) return Complex; + function Cos (X : Complex) return Complex; + function Tan (X : Complex) return Complex; + function Cot (X : Complex) return Complex; + function Arcsin (X : Complex) return Complex; + function Arccos (X : Complex) return Complex; + function Arctan (X : Complex) return Complex; + function Arccot (X : Complex) return Complex; + function Sinh (X : Complex) return Complex; + function Cosh (X : Complex) return Complex; + function Tanh (X : Complex) return Complex; + function Coth (X : Complex) return Complex; + function Arcsinh (X : Complex) return Complex; + function Arccosh (X : Complex) return Complex; + function Arctanh (X : Complex) return Complex; + function Arccoth (X : Complex) return Complex; +end Ada.Numerics.Generic_Complex_Elementary_Functions; + +The library package Numerics.Complex_Elementary_Functions is declared pure and defines the same +subprograms as Numerics.Generic_Complex_Elementary_Functions, except that the predefined type Float +is systematically substituted for Real'Base, and the Complex and Imaginary types exported by Numerics.- +Complex_Types are systematically substituted for Complex and Imaginary, throughout. Nongeneric +equivalents of Numerics.Generic_Complex_Elementary_Functions corresponding to each of the other +predefined floating point types are defined similarly, with the names Numerics.Short_Complex_- +Elementary_Functions, Numerics.Long_Complex_Elementary_Functions, etc. + +The overloading of the Exp function for the pure-imaginary type is provided to give the user an alternate +way to compose a complex value from a given modulus and argument. In addition to Compose_From_- +Polar(Rho, Theta) (see G.1.1), the programmer may write Rho * Exp(i * Theta). + +The imaginary (resp., real) component of the parameter X of the forward hyperbolic (resp., trigonometric) +functions and of the Exp function (and the parameter X, itself, in the case of the overloading of the Exp + +G.1.1 Complex Types + +13 December 2012 706 + +1 + +2/2 + +3 + +4 + +5 + +6 + +7 + +8 + +9/1 + +10 + +11 + + Ada Reference Manual — 2012 Edition + +function for the pure-imaginary type) represents an angle measured in radians, as does the imaginary +(resp., real) component of the result of the Log and inverse hyperbolic (resp., trigonometric) functions. + +The functions have their usual mathematical meanings. However, the arbitrariness inherent in the +placement of branch cuts, across which some of the complex elementary functions exhibit discontinuities, +is eliminated by the following conventions: + +• The imaginary component of the result of the Sqrt and Log functions is discontinuous as the + +parameter X crosses the negative real axis. + +• The result of the exponentiation operator when the left operand is of complex type is + +discontinuous as that operand crosses the negative real axis. + +• The imaginary component of the result of the Arcsin, Arccos, and Arctanh functions is + +discontinuous as the parameter X crosses the real axis to the left of –1.0 or the right of 1.0. + +• The real component of the result of the Arctan and Arcsinh functions is discontinuous as the + +parameter X crosses the imaginary axis below –i or above i. + +• The real component of the result of the Arccot function is discontinuous as the parameter X + +crosses the imaginary axis below –i or above i. + +• The imaginary component of the Arccosh function is discontinuous as the parameter X crosses + +the real axis to the left of 1.0. + +• The imaginary component of the result of the Arccoth function is discontinuous as the parameter + +X crosses the real axis between –1.0 and 1.0. + +The computed results of the mathematically multivalued functions are rendered single-valued by the +following conventions, which are meant to imply that the principal branch is an analytic continuation of +the corresponding real-valued function in Numerics.Generic_Elementary_Functions. (For Arctan and +Arccot, the single-argument function in question is that obtained from the two-argument version by fixing +the second argument to be its default value.) + +• The real component of the result of the Sqrt and Arccosh functions is nonnegative. +• The same convention applies to the imaginary component of the result of the Log function as +function of +the natural-cycle version of + +the Argument + +the + +to + +result of +applies +Numerics.Generic_Complex_Types (see G.1.1). + +• The range of the real (resp., imaginary) component of the result of the Arcsin and Arctan (resp., + +Arcsinh and Arctanh) functions is approximately –π/2.0 to π/2.0. + +• The real (resp., imaginary) component of the result of the Arccos and Arccot (resp., Arccoth) + +functions ranges from 0.0 to approximately π. + +• The range of the imaginary component of the result of the Arccosh function is approximately –π + +to π. + +In addition, the exponentiation operator inherits the single-valuedness of the Log function. + +Dynamic Semantics + +The exception Numerics.Argument_Error is raised by the exponentiation operator, signaling a parameter +value outside the domain of the corresponding mathematical function, when the value of the left operand is +zero and the real component of the exponent (or the exponent itself, when it is of real type) is zero. + +The exception Constraint_Error is raised, signaling a pole of the mathematical function (analogous to +dividing by zero), in the following cases, provided that Complex_Types.Real'Machine_Overflows is True: + +• by the Log, Cot, and Coth functions, when the value of the parameter X is zero; + +707 13 December 2012 + +Complex Elementary Functions G.1.2 + +12 + +13 + +14 + +15/2 + +16/2 + +17/2 + +18 + +19 + +20/2 + +21 + +22 + +23 + +24 + +25 + +26 + +27 + +28 + +29 + + Ada Reference Manual — 2012 Edition + +30 + +31 + +32 + +33 + +34 + +35 + +36 + +37 + +38 + +39 + +40 + +41/2 + +42 + +43 + +44 + +45 + +46 + +• by the exponentiation operator, when the value of the left operand is zero and the real + +component of the exponent (or the exponent itself, when it is of real type) is negative; + +• by the Arctan and Arccot functions, when the value of the parameter X is ± i; +• by the Arctanh and Arccoth functions, when the value of the parameter X is ± 1.0. + +Constraint_Error can also be raised when a finite result overflows (see G.2.6); this may occur for +parameter values sufficiently near poles, and, in the case of some of the functions, for parameter values +having components of sufficiently large magnitude. When Complex_Types.Real'Machine_Overflows is +False, the result at poles is unspecified. + +Implementation Requirements + +In the implementation of Numerics.Generic_Complex_Elementary_Functions, the range of intermediate +values allowed during the calculation of a final result shall not be affected by any range constraint of the +subtype Complex_Types.Real. + +In the following cases, evaluation of a complex elementary function shall yield the prescribed result (or a +result having the prescribed component), provided that the preceding rules do not call for an exception to +be raised: + +• When the parameter X has the value zero, the Sqrt, Sin, Arcsin, Tan, Arctan, Sinh, Arcsinh, +Tanh, and Arctanh functions yield a result of zero; the Exp, Cos, and Cosh functions yield a +result of one; the Arccos and Arccot functions yield a real result; and the Arccoth function yields +an imaginary result. + +• When the parameter X has the value one, the Sqrt function yields a result of one; the Log, +Arccos, and Arccosh functions yield a result of zero; and the Arcsin function yields a real result. + +• When the parameter X has the value –1.0, the Sqrt function yields the result + +• + +i (resp., –i), when the sign of the imaginary component of X is positive (resp., negative), if +Complex_Types.Real'Signed_Zeros is True; + +• + +i, if Complex_Types.Real'Signed_Zeros is False; + +• When the parameter X has the value –1.0, the Log function yields an imaginary result; and the + +Arcsin and Arccos functions yield a real result. + +• When the parameter X has the value ± i, the Log function yields an imaginary result. +• Exponentiation by a zero exponent yields the value one. Exponentiation by a unit exponent +yields the value of the left operand (as a complex value). Exponentiation of the value one yields +the value one. Exponentiation of the value zero yields the value zero. + +Other accuracy requirements for the complex elementary functions, which apply only in the strict mode, +are given in G.2.6. + +The sign of a zero result or zero result component yielded by a complex elementary function is +implementation defined when Complex_Types.Real'Signed_Zeros is True. + +The nongeneric equivalent packages may, but need not, be actual instantiations of the generic package +with the appropriate predefined nongeneric equivalent of Numerics.Generic_Complex_Types; if they are, +then the latter shall have been obtained by actual instantiation of Numerics.Generic_Complex_Types. + +Implementation Permissions + +G.1.2 Complex Elementary Functions + +13 December 2012 708 + + Ada Reference Manual — 2012 Edition + +The exponentiation operator may be implemented in terms of the Exp and Log functions. Because this +implementation yields poor accuracy in some parts of the domain, no accuracy requirement is imposed on +complex exponentiation. + +The implementation of the Exp function of a complex parameter X is allowed to raise the exception +Constraint_Error, signaling overflow, when the real component of X exceeds an unspecified threshold that +is approximately log(Complex_Types.Real'Safe_Last). This permission recognizes the impracticality of +avoiding overflow in the marginal case that the exponential of the real component of X exceeds the safe +range of Complex_Types.Real but both components of the final result do not. Similarly, the Sin and Cos +(resp., Sinh and Cosh) functions are allowed to raise the exception Constraint_Error, signaling overflow, +when the absolute value of the imaginary (resp., real) component of the parameter X exceeds an +unspecified threshold that is approximately log(Complex_Types.Real'Safe_Last) + log(2.0). This +permission recognizes the impracticality of avoiding overflow in the marginal case that the hyperbolic sine +or cosine of the imaginary (resp., real) component of X exceeds the safe range of Complex_Types.Real but +both components of the final result do not. + +Implementation Advice + +Implementations in which Complex_Types.Real'Signed_Zeros is True should attempt to provide a rational +treatment of the signs of zero results and result components. For example, many of the complex +elementary functions have components that are odd functions of one of the parameter components; in these +cases, the result component should have the sign of the parameter component at the origin. Other complex +elementary functions have zero components whose sign is opposite that of a parameter component at the +origin, or is always positive or always negative. + +G.1.3 Complex Input-Output + +The generic package Text_IO.Complex_IO defines procedures for the formatted input and output of +complex values. The generic actual parameter in an instantiation of Text_IO.Complex_IO is an instance of +Numerics.Generic_Complex_Types for some floating point subtype. Exceptional conditions are reported +by raising the appropriate exception defined in Text_IO. + +The generic library package Text_IO.Complex_IO has the following declaration: + +Static Semantics + +with Ada.Numerics.Generic_Complex_Types; +generic + with package Complex_Types is + new Ada.Numerics.Generic_Complex_Types (<>); +package Ada.Text_IO.Complex_IO is + use Complex_Types; + Default_Fore : Field := 2; + Default_Aft : Field := Real'Digits - 1; + Default_Exp : Field := 3; + procedure Get (File : in File_Type; + Item : out Complex; + Width : in Field := 0); + procedure Get (Item : out Complex; + Width : in Field := 0); + +47 + +48 + +49 + +1 + +2 + +3 + +4 + +5 + +6 + +709 13 December 2012 + +Complex Elementary Functions G.1.2 + + Ada Reference Manual — 2012 Edition + + procedure Put (File : in File_Type; + Item : in Complex; + Fore : in Field := Default_Fore; + Aft : in Field := Default_Aft; + Exp : in Field := Default_Exp); + procedure Put (Item : in Complex; + Fore : in Field := Default_Fore; + Aft : in Field := Default_Aft; + Exp : in Field := Default_Exp); + procedure Get (From : in String; + Item : out Complex; + Last : out Positive); + procedure Put (To : out String; + Item : in Complex; + Aft : in Field := Default_Aft; + Exp : in Field := Default_Exp); + +end Ada.Text_IO.Complex_IO; + +the predefined + +The library package Complex_Text_IO defines the same subprograms as Text_IO.Complex_IO, except +that +type +systematically +Numerics.Complex_Types.Complex is systematically substituted for Complex throughout. Nongeneric +equivalents of Text_IO.Complex_IO corresponding to each of the other predefined floating point types are +defined similarly, with the names Short_Complex_Text_IO, Long_Complex_Text_IO, etc. + +type Float + +for Real, + +substituted + +and + +the + +is + +The semantics of the Get and Put procedures are as follows: + +procedure Get (File : in File_Type; + Item : out Complex; + Width : in Field := 0); +procedure Get (Item : out Complex; + Width : in Field := 0); + +The input sequence is a pair of optionally signed real literals representing the real and imaginary +components of a complex value. These components have the format defined for the +corresponding Get procedure of an instance of Text_IO.Float_IO (see A.10.9) for the base +subtype of Complex_Types.Real. The pair of components may be separated by a comma or +surrounded by a pair of parentheses or both. Blanks are freely allowed before each of the +components and before the parentheses and comma, if either is used. If the value of the +parameter Width is zero, then + +• +• + +line and page terminators are also allowed in these places; + +the components shall be separated by at least one blank or line terminator if the +comma is omitted; and + +• reading stops when the right parenthesis has been read, if the input sequence includes a + +left parenthesis, or when the imaginary component has been read, otherwise. + +7 + +8 + +9 + +9.1/2 + +10 + +11 + +12/1 + +13 + +14 + +15 + +15.1 + +If a nonzero value of Width is supplied, then + +16 + +17 + +18 + +19 + +• +the components shall be separated by at least one blank if the comma is omitted; and +• exactly Width characters are read, or the characters (possibly none) up to a line + +terminator, whichever comes first (blanks are included in the count). + +Returns, in the parameter Item, the value of type Complex that corresponds to the input +sequence. + +The exception Text_IO.Data_Error is raised if the input sequence does not have the required +syntax or if the components of the complex value obtained are not of the base subtype of +Complex_Types.Real. + +G.1.3 Complex Input-Output + +13 December 2012 710 + + Ada Reference Manual — 2012 Edition + +procedure Put (File : in File_Type; + Item : in Complex; + Fore : in Field := Default_Fore; + Aft : in Field := Default_Aft; + Exp : in Field := Default_Exp); +procedure Put (Item : in Complex; + Fore : in Field := Default_Fore; + Aft : in Field := Default_Aft; + Exp : in Field := Default_Exp); + +Outputs the value of the parameter Item as a pair of decimal literals representing the real and +imaginary components of the complex value, using the syntax of an aggregate. More +specifically, + +• outputs a left parenthesis; +• outputs the value of the real component of the parameter Item with the format defined +by the corresponding Put procedure of an instance of Text_IO.Float_IO for the base +subtype of Complex_Types.Real, using the given values of Fore, Aft, and Exp; + +• outputs a comma; +• outputs the value of the imaginary component of the parameter Item with the format +defined by the corresponding Put procedure of an instance of Text_IO.Float_IO for the +base subtype of Complex_Types.Real, using the given values of Fore, Aft, and Exp; + +• outputs a right parenthesis. + +procedure Get (From : in String; + Item : out Complex; + Last : out Positive); + +20 + +21 + +22 + +23 + +24 + +25 + +26 + +27 + +Reads a complex value from the beginning of the given string, following the same rule as the +Get procedure that reads a complex value from a file, but treating the end of the string as a file +terminator. Returns, in the parameter Item, the value of type Complex that corresponds to the +input sequence. Returns in Last the index value such that From(Last) is the last character read. + +28/2 + +The exception Text_IO.Data_Error is raised if the input sequence does not have the required +syntax or if the components of the complex value obtained are not of the base subtype of +Complex_Types.Real. + +procedure Put (To : out String; + Item : in Complex; + Aft : in Field := Default_Aft; + Exp : in Field := Default_Exp); + +Outputs the value of the parameter Item to the given string as a pair of decimal literals +representing the real and imaginary components of the complex value, using the syntax of an +aggregate. More specifically, + +• a left parenthesis, the real component, and a comma are left justified in the given +string, with the real component having the format defined by the Put procedure (for +output to a file) of an instance of Text_IO.Float_IO for the base subtype of +Complex_Types.Real, using a value of zero for Fore and the given values of Aft and +Exp; + +• + +the imaginary component and a right parenthesis are right justified in the given string, +with the imaginary component having the format defined by the Put procedure (for +output to a file) of an instance of Text_IO.Float_IO for the base subtype of +Complex_Types.Real, using a value for Fore that completely fills the remainder of the +string, together with the given values of Aft and Exp. + +29 + +30 + +31 + +32 + +33 + +711 13 December 2012 + +Complex Input-Output G.1.3 + + Ada Reference Manual — 2012 Edition + +34 + +35 + +1 + +The exception Text_IO.Layout_Error is raised if the given string is too short to hold the +formatted output. + +Other exceptions declared (by renaming) in Text_IO may be raised by the preceding procedures in the +appropriate circumstances, as for the corresponding procedures of Text_IO.Float_IO. + +Implementation Permissions + +G.1.4 The Package Wide_Text_IO.Complex_IO + +Static Semantics + +Implementations shall also provide the generic library package Wide_Text_IO.Complex_IO. Its +declaration is obtained from that of Text_IO.Complex_IO by systematically replacing Text_IO by +Wide_Text_IO and String by Wide_String; the description of its behavior is obtained by additionally +replacing references to particular characters (commas, parentheses, etc.) by those for the corresponding +wide characters. + +G.1.5 The Package Wide_Wide_Text_IO.Complex_IO + +Static Semantics + +1/2 + +Implementations shall also provide the generic library package Wide_Wide_Text_IO.Complex_IO. Its +declaration is obtained from that of Text_IO.Complex_IO by systematically replacing Text_IO by +Wide_Wide_Text_IO and String by Wide_Wide_String; the description of its behavior is obtained by +additionally replacing references to particular characters (commas, parentheses, etc.) by those for the +corresponding wide wide characters. + +G.2 Numeric Performance Requirements + +Implementation Requirements + +Implementations shall provide a user-selectable mode in which the accuracy and other numeric +performance requirements detailed in the following subclauses are observed. This mode, referred to as the +strict mode, may or may not be the default mode; it directly affects the results of the predefined arithmetic +operations of real types and the results of the subprograms in children of the Numerics package, and +indirectly affects the operations in other language defined packages. Implementations shall also provide +the opposing mode, which is known as the relaxed mode. + +Either mode may be the default mode. + +The two modes need not actually be different. + +Implementation Permissions + +1 + +2 + +3 + +G.1.3 Complex Input-Output + +13 December 2012 712 + + Ada Reference Manual — 2012 Edition + +G.2.1 Model of Floating Point Arithmetic + +In the strict mode, the predefined operations of a floating point type shall satisfy the accuracy +requirements specified here and shall avoid or signal overflow in the situations described. This behavior is +presented in terms of a model of floating point arithmetic that builds on the concept of the canonical form +(see A.5.3). + +Static Semantics + +Associated with each floating point type is an infinite set of model numbers. The model numbers of a type +are used to define the accuracy requirements that have to be satisfied by certain predefined operations of +the type; through certain attributes of the model numbers, they are also used to explain the meaning of a +user-declared floating point type declaration. The model numbers of a derived type are those of the parent +type; the model numbers of a subtype are those of its type. + +The model numbers of a floating point type T are zero and all the values expressible in the canonical form +(for the type T), in which mantissa has T'Model_Mantissa digits and exponent has a value greater than or +equal to T'Model_Emin. (These attributes are defined in G.2.2.) + +A model interval of a floating point type is any interval whose bounds are model numbers of the type. The +model interval of a type T associated with a value v is the smallest model interval of T that includes v. +(The model interval associated with a model number of a type consists of that number only.) + +Implementation Requirements + +The accuracy requirements for the evaluation of certain predefined operations of floating point types are as +follows. + +An operand interval is the model interval, of the type specified for the operand of an operation, associated +with the value of the operand. + +For any predefined arithmetic operation that yields a result of a floating point type T, the required bounds +on the result are given by a model interval of T (called the result interval) defined in terms of the operand +values as follows: + +• The result interval is the smallest model interval of T that includes the minimum and the +maximum of all the values obtained by applying the (exact) mathematical operation to values +arbitrarily selected from the respective operand intervals. + +The result interval of an exponentiation is obtained by applying the above rule to the sequence of +multiplications defined by the exponent, assuming arbitrary association of the factors, and to the final +division in the case of a negative exponent. + +The result interval of a conversion of a numeric value to a floating point type T is the model interval of T +associated with the operand value, except when the source expression is of a fixed point type with a small +that is not a power of T'Machine_Radix or is a fixed point multiplication or division either of whose +operands has a small that is not a power of T'Machine_Radix; in these cases, the result interval is +implementation defined. + +For any of the foregoing operations, the implementation shall deliver a value that belongs to the result +interval when both bounds of the result interval are in the safe range of the result type T, as determined by +the values of T'Safe_First and T'Safe_Last; otherwise, + +• + +if T'Machine_Overflows is True, the implementation shall either deliver a value that belongs to +the result interval or raise Constraint_Error; + +1 + +2 + +3 + +4 + +5 + +6 + +7 + +8 + +9 + +10 + +11 + +12 + +713 13 December 2012 + +Model of Floating Point Arithmetic G.2.1 + + 13 + +14 + +15 + +16 + +1 + +2 + +3/2 + +3.1/2 + +3.2/2 + +Ada Reference Manual — 2012 Edition + +• + +if T'Machine_Overflows is False, the result is implementation defined. + +For any predefined relation on operands of a floating point type T, the implementation may deliver any +value (i.e., either True or False) obtained by applying the (exact) mathematical comparison to values +arbitrarily chosen from the respective operand intervals. + +The result of a membership test is defined in terms of comparisons of the operand value with the lower and +upper bounds of the given range or type mark (the usual rules apply to these comparisons). + +If the underlying floating point hardware implements division as multiplication by a reciprocal, the result +interval for division (and exponentiation by a negative exponent) is implementation defined. + +Implementation Permissions + +G.2.2 Model-Oriented Attributes of Floating Point Types + +In implementations that support the Numerics Annex, the model-oriented attributes of floating point types +shall yield the values defined here, in both the strict and the relaxed modes. These definitions add +conditions to those in A.5.3. + +For every subtype S of a floating point type T: + +S'Model_Mantissa + +Static Semantics + +Yields the number of digits in the mantissa of the canonical form of the model numbers of T +(see A.5.3). The value of this attribute shall be greater than or equal to + +d · log(10) / log(T'Machine_Radix) + g + +where d is the requested decimal precision of T, and g is 0 if T'Machine_Radix is a positive +power of 10 and 1 otherwise. In addition, T'Model_Mantissa shall be less than or equal to +the value of T'Machine_Mantissa. This attribute yields a value of +type +universal_integer. + +the + +4 + +S'Model_Emin + +5 + +S'Safe_First + +6 + +S'Safe_Last + +Yields the minimum exponent of the canonical form of the model numbers of T (see A.5.3). +The value of this attribute shall be greater than or equal to the value of T'Machine_Emin. +This attribute yields a value of the type universal_integer. + +Yields the lower bound of the safe range of T. The value of this attribute shall be a model +number of T and greater than or equal to the lower bound of the base range of T. In +addition, if T is declared by a floating_point_definition or is derived from such a type, and +the floating_point_definition includes a real_range_specification specifying a lower bound +of lb, then the value of this attribute shall be less than or equal to lb; otherwise, it shall be +less than or equal to –10.0 4 · d, where d is the requested decimal precision of T. This +attribute yields a value of the type universal_real. + +Yields the upper bound of the safe range of T. The value of this attribute shall be a model +number of T and less than or equal to the upper bound of the base range of T. In addition, if +T is declared by a floating_point_definition or is derived from such a type, and the +floating_point_definition includes a real_range_specification specifying an upper bound of +ub, then the value of this attribute shall be greater than or equal to ub; otherwise, it shall be +greater than or equal to 10.0 4 · d, where d is the requested decimal precision of T. This +attribute yields a value of the type universal_real. + +G.2.1 Model of Floating Point Arithmetic + +13 December 2012 714 + + + + + + + Ada Reference Manual — 2012 Edition + +S'Model + +Denotes a function (of a parameter X) whose specification is given in A.5.3. If X is a model +number of T, the function yields X; otherwise, it yields the value obtained by rounding or +truncating X to either one of the adjacent model numbers of T. Constraint_Error is raised if +the resulting model number is outside the safe range of S. A zero result has the sign of X +when S'Signed_Zeros is True. + +Subject to the constraints given above, the values of S'Model_Mantissa and S'Safe_Last are to be +maximized, and the values of S'Model_Emin and S'Safe_First minimized, by the implementation as +follows: + +• First, S'Model_Mantissa is set to the largest value for which values of S'Model_Emin, +S'Safe_First, and S'Safe_Last can be chosen so that the implementation satisfies the strict-mode +requirements of G.2.1 in terms of the model numbers and safe range induced by these attributes. +• Next, S'Model_Emin is set to the smallest value for which values of S'Safe_First and +S'Safe_Last can be chosen so that the implementation satisfies the strict-mode requirements of +G.2.1 in terms of the model numbers and safe range induced by these attributes and the +previously determined value of S'Model_Mantissa. + +• Finally, S'Safe_First and S'Safe_Last are set (in either order) to the smallest and largest values, +respectively, for which the implementation satisfies the strict-mode requirements of G.2.1 in +terms of the model numbers and safe range induced by these attributes and the previously +determined values of S'Model_Mantissa and S'Model_Emin. + +G.2.3 Model of Fixed Point Arithmetic + +In the strict mode, the predefined arithmetic operations of a fixed point type shall satisfy the accuracy +requirements specified here and shall avoid or signal overflow in the situations described. + +Implementation Requirements + +The accuracy requirements for the predefined fixed point arithmetic operations and conversions, and the +results of relations on fixed point operands, are given below. + +The operands of the fixed point adding operators, absolute value, and comparisons have the same type. +These operations are required to yield exact results, unless they overflow. + +Multiplications and divisions are allowed between operands of any two fixed point types; the result has to +be (implicitly or explicitly) converted to some other numeric type. For purposes of defining the accuracy +rules, the multiplication or division and the conversion are treated as a single operation whose accuracy +depends on three types (those of the operands and the result). For decimal fixed point types, the attribute +T'Round may be used to imply explicit conversion with rounding (see 3.5.10). + +When the result type is a floating point type, the accuracy is as given in G.2.1. For some combinations of +the operand and result types in the remaining cases, the result is required to belong to a small set of values +called the perfect result set; for other combinations, it is required merely to belong to a generally larger +and implementation-defined set of values called the close result set. When the result type is a decimal +fixed point type, the perfect result set contains a single value; thus, operations on decimal types are always +fully specified. + +When one operand of a fixed-fixed multiplication or division is of type universal_real, that operand is not +implicitly converted in the usual sense, since the context does not determine a unique target type, but the +accuracy of the result of the multiplication or division (i.e., whether the result has to belong to the perfect +result set or merely the close result set) depends on the value of the operand of type universal_real and on +the types of the other operand and of the result. + +7 + +8 + +9 + +10 + +11/3 + +1 + +2 + +3 + +4 + +5 + +6 + +715 13 December 2012 + +Model-Oriented Attributes of Floating Point Types G.2.2 + + Ada Reference Manual — 2012 Edition + +7 + +8 + +9 + +10 + +11 + +12 + +13 + +14/3 + +15 + +16 + +17 + +18 + +19 + +20 + +21 + +22 + +23 + +24 + +For a fixed point multiplication or division whose (exact) mathematical result is v, and for the conversion +of a value v to a fixed point type, the perfect result set and close result set are defined as follows: + +• If the result type is an ordinary fixed point type with a small of s, + +• + +if v is an integer multiple of s, then the perfect result set contains only the value v; + +• otherwise, it contains the integer multiple of s just below v and the integer multiple of s just + +above v. + + The close result set is an implementation-defined set of consecutive integer multiples of s + +containing the perfect result set as a subset. + +• If the result type is a decimal type with a small of s, + +• + +if v is an integer multiple of s, then the perfect result set contains only the value v; + +• otherwise, if truncation applies, then it contains only the integer multiple of s in the +direction toward zero, whereas if rounding applies, then it contains only the nearest integer +multiple of s (with ties broken by rounding away from zero). + + The close result set is an implementation-defined set of consecutive integer multiples of s + +containing the perfect result set as a subset. + +• If the result type is an integer type, + +• + +if v is an integer, then the perfect result set contains only the value v; + +• otherwise, it contains the integer nearest to the value v (if v lies equally distant from two + +consecutive integers, the perfect result set contains the one that is further from zero). + + The close result set is an implementation-defined set of consecutive integers containing the + +perfect result set as a subset. + +The result of a fixed point multiplication or division shall belong either to the perfect result set or to the +close result set, as described below, if overflow does not occur. In the following cases, if the result type is +a fixed point type, let s be its small; otherwise, i.e. when the result type is an integer type, let s be 1.0. +• For a multiplication or division neither of whose operands is of type universal_real, let l and r +be the smalls of the left and right operands. For a multiplication, if (l · r) / s is an integer or the +reciprocal of an integer (the smalls are said to be “compatible” in this case), the result shall +belong to the perfect result set; otherwise, it belongs to the close result set. For a division, if l / (r +· s) is an integer or the reciprocal of an integer (i.e., the smalls are compatible), the result shall +belong to the perfect result set; otherwise, it belongs to the close result set. + +• For a multiplication or division having one universal_real operand with a value of v, note that it +is always possible to factor v as an integer multiple of a “compatible” small, but the integer +multiple may be “too big.” If there exists a factorization in which that multiple is less than some +implementation-defined limit, the result shall belong to the perfect result set; otherwise, it +belongs to the close result set. + +A multiplication P * Q of an operand of a fixed point type F by an operand of an integer type I, or vice- +versa, and a division P / Q of an operand of a fixed point type F by an operand of an integer type I, are also +allowed. In these cases, the result has a type of F; explicit conversion of the result is never required. The +accuracy required in these cases is the same as that required for a multiplication F(P * Q) or a division F(P +/ Q) obtained by interpreting the operand of the integer type to have a fixed point type with a small of 1.0. + +The accuracy of the result of a conversion from an integer or fixed point type to a fixed point type, or from +a fixed point type to an integer type, is the same as that of a fixed point multiplication of the source value +by a fixed point operand having a small of 1.0 and a value of 1.0, as given by the foregoing rules. The +result of a conversion from a floating point type to a fixed point type shall belong to the close result set. + +G.2.3 Model of Fixed Point Arithmetic + +13 December 2012 716 + + Ada Reference Manual — 2012 Edition + +The result of a conversion of a universal_real operand to a fixed point type shall belong to the perfect +result set. + +The possibility of overflow in the result of a predefined arithmetic operation or conversion yielding a +result of a fixed point type T is analogous to that for floating point types, except for being related to the +base range instead of the safe range. If all of the permitted results belong to the base range of T, then the +implementation shall deliver one of the permitted results; otherwise, + +• + +• + +if T'Machine_Overflows is True, the implementation shall either deliver one of the permitted +results or raise Constraint_Error; + +if T'Machine_Overflows is False, the result is implementation defined. + +25 + +26 + +27 + +G.2.4 Accuracy Requirements for the Elementary Functions + +In the strict mode, the performance of Numerics.Generic_Elementary_Functions shall be as specified here. + +1 + +Implementation Requirements + +When an exception is not raised, the result of evaluating a function in an instance EF of +Numerics.Generic_Elementary_Functions belongs to a result interval, defined as the smallest model +interval of EF.Float_Type that contains all the values of the form f · (1.0 + d), where f is the exact value of +the corresponding mathematical function at the given parameter values, d is a real number, and |d| is less +than or equal to the function's maximum relative error. The function delivers a value that belongs to the +result interval when both of its bounds belong to the safe range of EF.Float_Type; otherwise, + +• + +• + +if EF.Float_Type'Machine_Overflows is True, the function either delivers a value that belongs +to the result interval or raises Constraint_Error, signaling overflow; + +if EF.Float_Type'Machine_Overflows is False, the result is implementation defined. + +The maximum relative error exhibited by each function is as follows: + +• 2.0 · EF.Float_Type'Model_Epsilon, in the case of the Sqrt, Sin, and Cos functions; +• 4.0 · EF.Float_Type'Model_Epsilon, in the case of the Log, Exp, Tan, Cot, and inverse + +trigonometric functions; and + +• 8.0 · EF.Float_Type'Model_Epsilon, in the case of the forward and inverse hyperbolic functions. + +The maximum relative error exhibited by the exponentiation operator, which depends on the values of the +operands, is (4.0 + |Right · log(Left)| / 32.0) · EF.Float_Type'Model_Epsilon. + +The maximum relative error given above applies throughout the domain of the forward trigonometric +functions when the Cycle parameter is specified. When the Cycle parameter is omitted, the maximum +relative error given above applies only when the absolute value of the angle parameter X is less than or +equal to some implementation-defined angle threshold, which shall be at least EF.Float_Type'Machine_- +Radix EF.Float_Type'Machine_Mantissa/2. Beyond the angle threshold, the accuracy of the forward trigonometric +functions is implementation defined. + +2 + +3 + +4 + +5 + +6 + +7 + +8 + +9 + +10 + +The prescribed results specified in A.5.1 for certain functions at particular parameter values take +precedence over the maximum relative error bounds; effectively, they narrow to a single value the result +interval allowed by the maximum relative error bounds. Additional rules with a similar effect are given by +table G-1 for the inverse trigonometric functions, at particular parameter values for which the +mathematical result is possibly not a model number of EF.Float_Type (or is, indeed, even transcendental). +In each table entry, the values of the parameters are such that the result lies on the axis between two + +11/2 + +717 13 December 2012 + +Model of Fixed Point Arithmetic G.2.3 + + Ada Reference Manual — 2012 Edition + +quadrants; the corresponding accuracy rule, which takes precedence over the maximum relative error +bounds, is that the result interval is the model interval of EF.Float_Type associated with the exact +mathematical result given in the table. + +12/1 + +This paragraph was deleted. + +13 + +The last line of the table is meant to apply when EF.Float_Type'Signed_Zeros is False; the two lines just +above it, when EF.Float_Type'Signed_Zeros is True and the parameter Y has a zero value with the +indicated sign. + + Table G-1: Tightly Approximated Elementary Function Results + + Function + +Value of X + +Value of Y + + Arcsin + Arcsin + Arccos + Arccos + Arctan and Arccot + Arctan and Arccot + Arctan and Arccot + Arctan and Arccot + Arctan and Arccot + +1.0 + +–1.0 + +0.0 + +–1.0 + +0.0 + +0.0 + +negative + +negative + +negative + +Exact +Result +when Cycle +Specified + +Cycle/4.0 + +–Cycle/4.0 + +Cycle/4.0 + +Cycle/2.0 + +n.a. + +n.a. + +n.a. + +n.a. + +positive + +Cycle/4.0 + +negative + +–Cycle/4.0 + ++0.0 + +–0.0 + +0.0 + +Cycle/2.0 + +–Cycle/2.0 + +Cycle/2.0 + +Exact +Result +when Cycle +Omitted +π/2.0 +–π/2.0 +π/2.0 +π +π/2.0 +–π/2.0 +π +–π +π + +14 + +15 + +16 + +17 + +18 + +19 + +The amount by which the result of an inverse trigonometric function is allowed to spill over into a +quadrant adjacent to the one corresponding to the principal branch, as given in A.5.1, is limited. The rule +is that the result belongs to the smallest model interval of EF.Float_Type that contains both boundaries of +the quadrant corresponding to the principal branch. This rule also takes precedence over the maximum +relative error bounds, effectively narrowing the result interval allowed by them. + +Finally, the following specifications also take precedence over the maximum relative error bounds: + +• The absolute value of the result of the Sin, Cos, and Tanh functions never exceeds one. +• The absolute value of the result of the Coth function is never less than one. +• The result of the Cosh function is never less than one. + +Implementation Advice + +The versions of the forward trigonometric functions without a Cycle parameter should not be implemented +by calling the corresponding version with a Cycle parameter of 2.0*Numerics.Pi, since this will not +provide the required accuracy in some portions of the domain. For the same reason, the version of Log +without a Base parameter should not be implemented by calling the corresponding version with a Base +parameter of Numerics.e. + +G.2.4 Accuracy Requirements for the Elementary Functions + +13 December 2012 718 + + + + Ada Reference Manual — 2012 Edition + +G.2.5 Performance Requirements for Random Number Generation + +In the strict mode, the performance of Numerics.Float_Random and Numerics.Discrete_Random shall be +as specified here. + +Implementation Requirements + +Two different calls to the time-dependent Reset procedure shall reset the generator to different states, +provided that the calls are separated in time by at least one second and not more than fifty years. + +The implementation's representations of generator states and its algorithms for generating random numbers +shall yield a period of at least 231–2; much longer periods are desirable but not required. + +The implementations of Numerics.Float_Random.Random and Numerics.Discrete_Random.Random shall +pass at least 85% of the individual trials in a suite of statistical tests. For Numerics.Float_Random, the +tests are applied directly to the floating point values generated (i.e., they are not converted to integers +first), while for Numerics.Discrete_Random they are applied to the generated values of various discrete +types. Each test suite performs 6 different tests, with each test repeated 10 times, yielding a total of 60 +individual trials. An individual trial is deemed to pass if the chi-square value (or other statistic) calculated +for the observed counts or distribution falls within the range of values corresponding to the 2.5 and 97.5 +percentage points for the relevant degrees of freedom (i.e., it shall be neither too high nor too low). For the +purpose of determining the degrees of freedom, measurement categories are combined whenever the +expected counts are fewer than 5. + +G.2.6 Accuracy Requirements for Complex Arithmetic + +In the strict mode, the performance of Numerics.Generic_Complex_Types and Numerics.Generic_- +Complex_Elementary_Functions shall be as specified here. + +Implementation Requirements + +When an exception is not raised, the result of evaluating a real function of an instance CT of +Numerics.Generic_Complex_Types (i.e., a function that yields a value of subtype CT.Real'Base or +CT.Imaginary) belongs to a result interval defined as for a real elementary function (see G.2.4). + +When an exception is not raised, each component of the result of evaluating a complex function of such an +instance, or of an +instance of Numerics.Generic_Complex_Elementary_Functions obtained by +instantiating the latter with CT (i.e., a function that yields a value of subtype CT.Complex), also belongs to +a result interval. The result intervals for the components of the result are either defined by a maximum +relative error bound or by a maximum box error bound. When the result interval for the real (resp., +imaginary) component is defined by maximum relative error, it is defined as for that of a real function, +relative to the exact value of the real (resp., imaginary) part of the result of the corresponding +mathematical function. When defined by maximum box error, the result interval for a component of the +result is the smallest model interval of CT.Real that contains all the values of the corresponding part of f · +(1.0 + d), where f is the exact complex value of the corresponding mathematical function at the given +parameter values, d is complex, and |d| is less than or equal to the given maximum box error. The function +delivers a value that belongs to the result interval (or a value both of whose components belong to their +respective result intervals) when both bounds of the result interval(s) belong to the safe range of CT.Real; +otherwise, + +1 + +2 + +3 + +4 + +1 + +2 + +3 + +719 13 December 2012 + +Performance Requirements for Random Number Generation G.2.5 + + Ada Reference Manual — 2012 Edition + +4 + +5 + +6/2 + +• + +• + +if CT.Real'Machine_Overflows is True, the function either delivers a value that belongs to the +result interval (or a value both of whose components belong to their respective result intervals) +or raises Constraint_Error, signaling overflow; + +if CT.Real'Machine_Overflows is False, the result is implementation defined. + +The error bounds for particular complex functions are tabulated in table G-2. In the table, the error bound +is given as the coefficient of CT.Real'Model_Epsilon. + +7/1 + +This paragraph was deleted. + + Table G-2: Error Bounds for Particular Complex Functions +Nature of +Result + +Nature of +Bound + + Function or Operator + +Error Bound + + Modulus + Argument + Compose_From_Polar + "*" (both operands complex) + "/" (right operand complex) + Sqrt + Log + Exp (complex parameter) + Exp (imaginary parameter) + Sin, Cos, Sinh, and Cosh + Tan, Cot, Tanh, and Coth + inverse trigonometric + inverse hyperbolic + +real + +real + +complex + +complex + +complex + +complex + +complex + +complex + +complex + +complex + +complex + +complex + +complex + +max. rel. error + +max. rel. error + +max. rel. error + +max. box error + +max. box error + +max. rel. error + +max. box error + +max. rel. error + +max. rel. error + +max. rel. error + +max. rel. error + +max. rel. error + +max. rel. error + +3.0 + +4.0 + +3.0 + +5.0 + +13.0 + +6.0 + +13.0 + +7.0 + +2.0 + +11.0 + +35.0 + +14.0 + +14.0 + +8 + +9 + +The maximum relative error given above applies throughout the domain of the Compose_From_Polar +function when the Cycle parameter is specified. When the Cycle parameter is omitted, the maximum +relative error applies only when the absolute value of the parameter Argument is less than or equal to the +angle threshold (see G.2.4). For the Exp function, and for the forward hyperbolic (resp., trigonometric) +functions, the maximum relative error given above likewise applies only when the absolute value of the +imaginary (resp., real) component of the parameter X (or the absolute value of the parameter itself, in the +case of the Exp function with a parameter of pure-imaginary type) is less than or equal to the angle +threshold. For larger angles, the accuracy is implementation defined. + +The prescribed results specified in G.1.2 for certain functions at particular parameter values take +precedence over the error bounds; effectively, they narrow to a single value the result interval allowed by +the error bounds for a component of the result. Additional rules with a similar effect are given below for +certain inverse trigonometric and inverse hyperbolic functions, at particular parameter values for which a +component of the mathematical result is transcendental. In each case, the accuracy rule, which takes +precedence over the error bounds, is that the result interval for the stated result component is the model +interval of CT.Real associated with the component's exact mathematical value. The cases in question are +as follows: + +G.2.6 Accuracy Requirements for Complex Arithmetic + +13 December 2012 720 + + + + Ada Reference Manual — 2012 Edition + +• When the parameter X has the value zero, the real (resp., imaginary) component of the result of +the Arccot (resp., Arccoth) function is in the model interval of CT.Real associated with the value +π/2.0. + +• When the parameter X has the value one, the real component of the result of the Arcsin function + +is in the model interval of CT.Real associated with the value π/2.0. + +• When the parameter X has the value –1.0, the real component of the result of the Arcsin (resp., +Arccos) function is in the model interval of CT.Real associated with the value –π/2.0 (resp., π). + +The amount by which a component of the result of an inverse trigonometric or inverse hyperbolic function +is allowed to spill over into a quadrant adjacent to the one corresponding to the principal branch, as given +in G.1.2, is limited. The rule is that the result belongs to the smallest model interval of CT.Real that +contains both boundaries of the quadrant corresponding to the principal branch. This rule also takes +precedence over the maximum error bounds, effectively narrowing the result interval allowed by them. + +Finally, the results allowed by the error bounds are narrowed by one further rule: The absolute value of +each component of the result of the Exp function, for a pure-imaginary parameter, never exceeds one. + +The version of the Compose_From_Polar function without a Cycle parameter should not be implemented +by calling the corresponding version with a Cycle parameter of 2.0*Numerics.Pi, since this will not +provide the required accuracy in some portions of the domain. + +Implementation Advice + +G.3 Vector and Matrix Manipulation + +the manipulation of real vectors and matrices are provided + +Types and operations for +in +Generic_Real_Arrays, which is defined in G.3.1. Types and operations for the manipulation of complex +vectors and matrices are provided in Generic_Complex_Arrays, which is defined in G.3.2. Both of these +library units are generic children of the predefined package Numerics (see A.5). Nongeneric equivalents of +these packages for each of the predefined floating point types are also provided as children of Numerics. + +G.3.1 Real Vectors and Matrices + +The generic library package Numerics.Generic_Real_Arrays has the following declaration: + +Static Semantics + +generic + type Real is digits <>; +package Ada.Numerics.Generic_Real_Arrays is + pragma Pure(Generic_Real_Arrays); + -- Types + type Real_Vector is array (Integer range <>) of Real'Base; + type Real_Matrix is array (Integer range <>, Integer range <>) + of Real'Base; + -- Subprograms for Real_Vector types + -- Real_Vector arithmetic operations + function "+" (Right : Real_Vector) return Real_Vector; + function "-" (Right : Real_Vector) return Real_Vector; + function "abs" (Right : Real_Vector) return Real_Vector; + function "+" (Left, Right : Real_Vector) return Real_Vector; + function "-" (Left, Right : Real_Vector) return Real_Vector; + function "*" (Left, Right : Real_Vector) return Real'Base; + +10 + +11 + +12 + +13/2 + +14 + +15 + +1/2 + +1/2 + +2/2 + +3/2 + +4/2 + +5/2 + +6/2 + +7/2 + +8/2 + +9/2 + +721 13 December 2012 + +Accuracy Requirements for Complex Arithmetic G.2.6 + + 10/2 + +11/2 + +12/2 + +13/2 + +14/2 + +15/2 + +16/2 + +17/2 + +18/2 + +19/2 + +20/2 + +21/2 + +22/2 + +23/2 + +24/2 + +25/2 + +26/2 + +27/2 + +28/2 + +29/2 + +30/2 + +31/2 + +Ada Reference Manual — 2012 Edition + + function "abs" (Right : Real_Vector) return Real'Base; + -- Real_Vector scaling operations + function "*" (Left : Real'Base; Right : Real_Vector) + return Real_Vector; + function "*" (Left : Real_Vector; Right : Real'Base) + return Real_Vector; + function "/" (Left : Real_Vector; Right : Real'Base) + return Real_Vector; + -- Other Real_Vector operations + function Unit_Vector (Index : Integer; + Order : Positive; + First : Integer := 1) return Real_Vector; + -- Subprograms for Real_Matrix types + -- Real_Matrix arithmetic operations + function "+" (Right : Real_Matrix) return Real_Matrix; + function "-" (Right : Real_Matrix) return Real_Matrix; + function "abs" (Right : Real_Matrix) return Real_Matrix; + function Transpose (X : Real_Matrix) return Real_Matrix; + function "+" (Left, Right : Real_Matrix) return Real_Matrix; + function "-" (Left, Right : Real_Matrix) return Real_Matrix; + function "*" (Left, Right : Real_Matrix) return Real_Matrix; + function "*" (Left, Right : Real_Vector) return Real_Matrix; + function "*" (Left : Real_Vector; Right : Real_Matrix) + return Real_Vector; + function "*" (Left : Real_Matrix; Right : Real_Vector) + return Real_Vector; + -- Real_Matrix scaling operations + function "*" (Left : Real'Base; Right : Real_Matrix) + return Real_Matrix; + function "*" (Left : Real_Matrix; Right : Real'Base) + return Real_Matrix; + function "/" (Left : Real_Matrix; Right : Real'Base) + return Real_Matrix; + -- Real_Matrix inversion and related operations + function Solve (A : Real_Matrix; X : Real_Vector) return Real_Vector; + function Solve (A, X : Real_Matrix) return Real_Matrix; + function Inverse (A : Real_Matrix) return Real_Matrix; + function Determinant (A : Real_Matrix) return Real'Base; + -- Eigenvalues and vectors of a real symmetric matrix + function Eigenvalues (A : Real_Matrix) return Real_Vector; + procedure Eigensystem (A : in Real_Matrix; + Values : out Real_Vector; + Vectors : out Real_Matrix); + -- Other Real_Matrix operations + function Unit_Matrix (Order : Positive; + First_1, First_2 : Integer := 1) + return Real_Matrix; +end Ada.Numerics.Generic_Real_Arrays; + +The library package Numerics.Real_Arrays is declared pure and defines the same types and subprograms +as Numerics.Generic_Real_Arrays, except that the predefined type Float is systematically substituted for +Real'Base throughout. Nongeneric equivalents for each of the other predefined floating point types are +defined similarly, with the names Numerics.Short_Real_Arrays, Numerics.Long_Real_Arrays, etc. + +32/2 + +Two types are defined and exported by Numerics.Generic_Real_Arrays. The composite type Real_Vector +is provided to represent a vector with components of type Real; it is defined as an unconstrained, one- + +G.3.1 Real Vectors and Matrices + +13 December 2012 722 + + Ada Reference Manual — 2012 Edition + +dimensional array with an index of type Integer. The composite type Real_Matrix is provided to represent +a matrix with components of type Real; it is defined as an unconstrained, two-dimensional array with +indices of type Integer. + +The effect of the various subprograms is as described below. In most cases the subprograms are described +in terms of corresponding scalar operations of the type Real; any exception raised by those operations is +propagated by the array operation. Moreover, the accuracy of the result for each individual component is +as defined for the scalar operation unless stated otherwise. + +In the case of those operations which are defined to involve an inner product, Constraint_Error may be +raised if an intermediate result is outside the range of Real'Base even though the mathematical final result +would not be. + +function "+" (Right : Real_Vector) return Real_Vector; +function "-" (Right : Real_Vector) return Real_Vector; +function "abs" (Right : Real_Vector) return Real_Vector; + +Each operation returns the result of applying the corresponding operation of the type Real to +each component of Right. The index range of the result is Right'Range. + +function "+" (Left, Right : Real_Vector) return Real_Vector; +function "-" (Left, Right : Real_Vector) return Real_Vector; + +Each operation returns the result of applying the corresponding operation of the type Real to +each component of Left and the matching component of Right. The index range of the result is +Left'Range. Constraint_Error is raised if Left'Length is not equal to Right'Length. + +function "*" (Left, Right : Real_Vector) return Real'Base; + +This operation returns the inner product of Left and Right. Constraint_Error is raised if +Left'Length is not equal to Right'Length. This operation involves an inner product. + +function "abs" (Right : Real_Vector) return Real'Base; + +This operation returns the L2-norm of Right (the square root of the inner product of the vector +with itself). + +function "*" (Left : Real'Base; Right : Real_Vector) return Real_Vector; + +This operation returns the result of multiplying each component of Right by the scalar Left using +the "*" operation of the type Real. The index range of the result is Right'Range. + +function "*" (Left : Real_Vector; Right : Real'Base) return Real_Vector; +function "/" (Left : Real_Vector; Right : Real'Base) return Real_Vector; + +Each operation returns the result of applying the corresponding operation of the type Real to +each component of Left and to the scalar Right. The index range of the result is Left'Range. + +function Unit_Vector (Index : Integer; + Order : Positive; + First : Integer := 1) return Real_Vector; + +This function returns a unit vector with Order components and a lower bound of First. All +components are set to 0.0 except for the Index component which is set to 1.0. Constraint_Error is +raised if Index < First, Index > First + Order – 1 or if First + Order – 1 > Integer'Last. + +function "+" (Right : Real_Matrix) return Real_Matrix; +function "-" (Right : Real_Matrix) return Real_Matrix; +function "abs" (Right : Real_Matrix) return Real_Matrix; + +Each operation returns the result of applying the corresponding operation of the type Real to +each component of Right. The index ranges of the result are those of Right. + +33/2 + +34/2 + +35/2 + +36/2 + +37/2 + +38/2 + +39/2 + +40/2 + +41/2 + +42/2 + +43/2 + +44/2 + +45/2 + +46/2 + +47/2 + +48/2 + +49/2 + +50/2 + +723 13 December 2012 + +Real Vectors and Matrices G.3.1 + + Ada Reference Manual — 2012 Edition + +51/2 + +52/2 + +53/2 + +54/2 + +55/2 + +56/2 + +57/2 + +58/2 + +59/2 + +60/2 + +61/2 + +62/2 + +63/2 + +64/2 + +65/2 + +66/2 + +67/2 + +68/2 + +69/2 + +70/2 + +function Transpose (X : Real_Matrix) return Real_Matrix; + +This function returns the transpose of a matrix X. The first and second index ranges of the result +are X'Range(2) and X'Range(1) respectively. + +function "+" (Left, Right : Real_Matrix) return Real_Matrix; +function "-" (Left, Right : Real_Matrix) return Real_Matrix; + +Each operation returns the result of applying the corresponding operation of the type Real to +each component of Left and the matching component of Right. The index ranges of the result are +those of Left. Constraint_Error is raised if Left'Length(1) is not equal to Right'Length(1) or +Left'Length(2) is not equal to Right'Length(2). + +function "*" (Left, Right : Real_Matrix) return Real_Matrix; + +This operation provides the standard mathematical operation for matrix multiplication. The first +and second index ranges of the result are Left'Range(1) and Right'Range(2) respectively. +Constraint_Error is raised if Left'Length(2) is not equal to Right'Length(1). This operation +involves inner products. + +function "*" (Left, Right : Real_Vector) return Real_Matrix; + +This operation returns the outer product of a (column) vector Left by a (row) vector Right using +the operation "*" of the type Real for computing the individual components. The first and second +index ranges of the result are Left'Range and Right'Range respectively. + +function "*" (Left : Real_Vector; Right : Real_Matrix) return Real_Vector; + +This operation provides the standard mathematical operation for multiplication of a (row) vector +Left by a matrix Right. The index range of the (row) vector result is Right'Range(2). +Constraint_Error is raised if Left'Length is not equal to Right'Length(1). This operation involves +inner products. + +function "*" (Left : Real_Matrix; Right : Real_Vector) return Real_Vector; + +This operation provides the standard mathematical operation for multiplication of a matrix Left +by a (column) vector Right. The index range of the (column) vector result is Left'Range(1). +Constraint_Error is raised if Left'Length(2) is not equal to Right'Length. This operation involves +inner products. + +function "*" (Left : Real'Base; Right : Real_Matrix) return Real_Matrix; + +This operation returns the result of multiplying each component of Right by the scalar Left using +the "*" operation of the type Real. The index ranges of the result are those of Right. + +function "*" (Left : Real_Matrix; Right : Real'Base) return Real_Matrix; +function "/" (Left : Real_Matrix; Right : Real'Base) return Real_Matrix; + +Each operation returns the result of applying the corresponding operation of the type Real to +each component of Left and to the scalar Right. The index ranges of the result are those of Left. + +function Solve (A : Real_Matrix; X : Real_Vector) return Real_Vector; + +This function returns a vector Y such that X is (nearly) equal to A * Y. This is the standard +mathematical operation for solving a single set of linear equations. The index range of the result +is A'Range(2). Constraint_Error is raised if A'Length(1), A'Length(2), and X'Length are not +equal. Constraint_Error is raised if the matrix A is ill-conditioned. + +function Solve (A, X : Real_Matrix) return Real_Matrix; + +This function returns a matrix Y such that X is (nearly) equal to A * Y. This is the standard +mathematical operation for solving several sets of linear equations. The index ranges of the + +G.3.1 Real Vectors and Matrices + +13 December 2012 724 + + Ada Reference Manual — 2012 Edition + +result are A'Range(2) and X'Range(2). Constraint_Error is raised if A'Length(1), A'Length(2), +and X'Length(1) are not equal. Constraint_Error is raised if the matrix A is ill-conditioned. + +function Inverse (A : Real_Matrix) return Real_Matrix; + +This function returns a matrix B such that A * B is (nearly) equal to the unit matrix. The index +ranges of the result are A'Range(2) and A'Range(1). Constraint_Error is raised if A'Length(1) is +not equal to A'Length(2). Constraint_Error is raised if the matrix A is ill-conditioned. + +function Determinant (A : Real_Matrix) return Real'Base; + +This function returns the determinant of the matrix A. Constraint_Error is raised if A'Length(1) +is not equal to A'Length(2). + +function Eigenvalues(A : Real_Matrix) return Real_Vector; + +This function returns the eigenvalues of the symmetric matrix A as a vector sorted into order +with the largest first. Constraint_Error is raised if A'Length(1) is not equal to A'Length(2). The +index range of the result is A'Range(1). Argument_Error is raised if the matrix A is not +symmetric. + +procedure Eigensystem(A : in Real_Matrix; + Values : out Real_Vector; + Vectors : out Real_Matrix); + +This procedure computes both the eigenvalues and eigenvectors of the symmetric matrix A. The +out parameter Values is the same as that obtained by calling the function Eigenvalues. The out +parameter Vectors is a matrix whose columns are the eigenvectors of the matrix A. The order of +the columns corresponds to the order of the eigenvalues. The eigenvectors are normalized and +mutually orthogonal (they are orthonormal), including when there are repeated eigenvalues. +Constraint_Error is raised if A'Length(1) is not equal to A'Length(2), or if Values'Range is not +equal to A'Range(1), or if the index ranges of the parameter Vectors are not equal to those of A. +Argument_Error is raised if the matrix A is not symmetric. Constraint_Error is also raised in +implementation-defined circumstances if the algorithm used does not converge quickly enough. + +function Unit_Matrix (Order : Positive; + First_1, First_2 : Integer := 1) return Real_Matrix; + +This function returns a square unit matrix with Order**2 components and lower bounds of +First_1 and First_2 (for the first and second index ranges respectively). All components are set to +0.0 except for the main diagonal, whose components are set to 1.0. Constraint_Error is raised if +First_1 + Order – 1 > Integer'Last or First_2 + Order – 1 > Integer'Last. + +Implementation Requirements + +Accuracy requirements for the subprograms Solve, Inverse, Determinant, Eigenvalues and Eigensystem +are implementation defined. + +For operations not involving an inner product, the accuracy requirements are those of the corresponding +operations of the type Real in both the strict mode and the relaxed mode (see G.2). + +For operations involving an inner product, no requirements are specified in the relaxed mode. In the strict +mode the modulus of the absolute error of the inner product X*Y shall not exceed g*abs(X)*abs(Y) where +g is defined as + +g = X'Length * Real'Machine_Radix**(1 – Real'Model_Mantissa) + +For the L2-norm, no accuracy requirements are specified in the relaxed mode. In the strict mode the +relative error on the norm shall not exceed g / 2.0 + 3.0 * Real'Model_Epsilon where g is defined as above. + +725 13 December 2012 + +Real Vectors and Matrices G.3.1 + +71/2 + +72/2 + +73/2 + +74/2 + +75/2 + +76/2 + +77/2 + +78/3 + +79/2 + +80/2 + +81/2 + +82/2 + +83/2 + +84/2 + +85/2 + + Ada Reference Manual — 2012 Edition + +86/2 + +Implementations shall document any techniques used to reduce cancellation errors such as extended +precision arithmetic. + +Documentation Requirements + +87/2 + +The nongeneric equivalent packages may, but need not, be actual instantiations of the generic package for +the appropriate predefined type. + +Implementation Permissions + +88/3 + +89/2 + +90/2 + +91/3 + +1/2 + +2/2 + +3/2 + +4/2 + +5/2 + +6/2 + +7/2 + +8/2 + +9/2 + +Implementation Advice + +Implementations should implement the Solve and Inverse functions using established techniques such as +LU decomposition with row interchanges followed by back and forward substitution. Implementations are +recommended to refine the result by performing an iteration on the residuals; if this is done, then it should +be documented. + +It is not the intention that any special provision should be made to determine whether a matrix is ill- +conditioned or not. The naturally occurring overflow (including division by zero) which will result from +executing these functions with an ill-conditioned matrix and thus raise Constraint_Error is sufficient. + +The test that a matrix is symmetric should be performed by using the equality operator to compare the +relevant components. + +An implementation should minimize the circumstances under which the algorithm used for Eigenvalues +and Eigensystem fails to converge. + +G.3.2 Complex Vectors and Matrices + +Static Semantics + +The generic library package Numerics.Generic_Complex_Arrays has the following declaration: + +with Ada.Numerics.Generic_Real_Arrays, Ada.Numerics.Generic_Complex_Types; +generic + with package Real_Arrays is new + Ada.Numerics.Generic_Real_Arrays (<>); + use Real_Arrays; + with package Complex_Types is new + Ada.Numerics.Generic_Complex_Types (Real); + use Complex_Types; +package Ada.Numerics.Generic_Complex_Arrays is + pragma Pure(Generic_Complex_Arrays); + -- Types + type Complex_Vector is array (Integer range <>) of Complex; + type Complex_Matrix is array (Integer range <>, + Integer range <>) of Complex; + -- Subprograms for Complex_Vector types + -- Complex_Vector selection, conversion and composition operations + function Re (X : Complex_Vector) return Real_Vector; + function Im (X : Complex_Vector) return Real_Vector; + procedure Set_Re (X : in out Complex_Vector; + Re : in Real_Vector); + procedure Set_Im (X : in out Complex_Vector; + Im : in Real_Vector); + function Compose_From_Cartesian (Re : Real_Vector) + return Complex_Vector; + function Compose_From_Cartesian (Re, Im : Real_Vector) + return Complex_Vector; + +G.3.1 Real Vectors and Matrices + +13 December 2012 726 + + Ada Reference Manual — 2012 Edition + + function Modulus (X : Complex_Vector) return Real_Vector; + function "abs" (Right : Complex_Vector) return Real_Vector + renames Modulus; + function Argument (X : Complex_Vector) return Real_Vector; + function Argument (X : Complex_Vector; + Cycle : Real'Base) return Real_Vector; + function Compose_From_Polar (Modulus, Argument : Real_Vector) + return Complex_Vector; + function Compose_From_Polar (Modulus, Argument : Real_Vector; + Cycle : Real'Base) + return Complex_Vector; + -- Complex_Vector arithmetic operations + function "+" (Right : Complex_Vector) return Complex_Vector; + function "-" (Right : Complex_Vector) return Complex_Vector; + function Conjugate (X : Complex_Vector) return Complex_Vector; + function "+" (Left, Right : Complex_Vector) return Complex_Vector; + function "-" (Left, Right : Complex_Vector) return Complex_Vector; + function "*" (Left, Right : Complex_Vector) return Complex; + function "abs" (Right : Complex_Vector) return Real'Base; + -- Mixed Real_Vector and Complex_Vector arithmetic operations + function "+" (Left : Real_Vector; + Right : Complex_Vector) return Complex_Vector; + function "+" (Left : Complex_Vector; + Right : Real_Vector) return Complex_Vector; + function "-" (Left : Real_Vector; + Right : Complex_Vector) return Complex_Vector; + function "-" (Left : Complex_Vector; + Right : Real_Vector) return Complex_Vector; + function "*" (Left : Real_Vector; Right : Complex_Vector) + return Complex; + function "*" (Left : Complex_Vector; Right : Real_Vector) + return Complex; + -- Complex_Vector scaling operations + function "*" (Left : Complex; + Right : Complex_Vector) return Complex_Vector; + function "*" (Left : Complex_Vector; + Right : Complex) return Complex_Vector; + function "/" (Left : Complex_Vector; + Right : Complex) return Complex_Vector; + function "*" (Left : Real'Base; + Right : Complex_Vector) return Complex_Vector; + function "*" (Left : Complex_Vector; + Right : Real'Base) return Complex_Vector; + function "/" (Left : Complex_Vector; + Right : Real'Base) return Complex_Vector; + -- Other Complex_Vector operations + function Unit_Vector (Index : Integer; + Order : Positive; + First : Integer := 1) return Complex_Vector; + -- Subprograms for Complex_Matrix types + -- Complex_Matrix selection, conversion and composition operations + function Re (X : Complex_Matrix) return Real_Matrix; + function Im (X : Complex_Matrix) return Real_Matrix; + procedure Set_Re (X : in out Complex_Matrix; + Re : in Real_Matrix); + procedure Set_Im (X : in out Complex_Matrix; + Im : in Real_Matrix); + +10/2 + +11/2 + +12/2 + +13/2 + +14/2 + +15/2 + +16/3 + +17/2 + +18/2 + +19/2 + +20/2 + +21/2 + +22/2 + +23/2 + +24/2 + +25/2 + +26/2 + +27/2 + +28/2 + +727 13 December 2012 + +Complex Vectors and Matrices G.3.2 + + Ada Reference Manual — 2012 Edition + +29/2 + +30/2 + +31/2 + +32/2 + +33/2 + +34/2 + +35/2 + +36/2 + +37/2 + +38/2 + +39/2 + +40/2 + +41/2 + +42/2 + +43/2 + + function Compose_From_Cartesian (Re : Real_Matrix) + return Complex_Matrix; + function Compose_From_Cartesian (Re, Im : Real_Matrix) + return Complex_Matrix; + function Modulus (X : Complex_Matrix) return Real_Matrix; + function "abs" (Right : Complex_Matrix) return Real_Matrix + renames Modulus; + function Argument (X : Complex_Matrix) return Real_Matrix; + function Argument (X : Complex_Matrix; + Cycle : Real'Base) return Real_Matrix; + function Compose_From_Polar (Modulus, Argument : Real_Matrix) + return Complex_Matrix; + function Compose_From_Polar (Modulus, Argument : Real_Matrix; + Cycle : Real'Base) + return Complex_Matrix; + -- Complex_Matrix arithmetic operations + function "+" (Right : Complex_Matrix) return Complex_Matrix; + function "-" (Right : Complex_Matrix) return Complex_Matrix; + function Conjugate (X : Complex_Matrix) return Complex_Matrix; + function Transpose (X : Complex_Matrix) return Complex_Matrix; + function "+" (Left, Right : Complex_Matrix) return Complex_Matrix; + function "-" (Left, Right : Complex_Matrix) return Complex_Matrix; + function "*" (Left, Right : Complex_Matrix) return Complex_Matrix; + function "*" (Left, Right : Complex_Vector) return Complex_Matrix; + function "*" (Left : Complex_Vector; + Right : Complex_Matrix) return Complex_Vector; + function "*" (Left : Complex_Matrix; + Right : Complex_Vector) return Complex_Vector; + -- Mixed Real_Matrix and Complex_Matrix arithmetic operations + function "+" (Left : Real_Matrix; + Right : Complex_Matrix) return Complex_Matrix; + function "+" (Left : Complex_Matrix; + Right : Real_Matrix) return Complex_Matrix; + function "-" (Left : Real_Matrix; + Right : Complex_Matrix) return Complex_Matrix; + function "-" (Left : Complex_Matrix; + Right : Real_Matrix) return Complex_Matrix; + function "*" (Left : Real_Matrix; + Right : Complex_Matrix) return Complex_Matrix; + function "*" (Left : Complex_Matrix; + Right : Real_Matrix) return Complex_Matrix; + function "*" (Left : Real_Vector; + Right : Complex_Vector) return Complex_Matrix; + function "*" (Left : Complex_Vector; + Right : Real_Vector) return Complex_Matrix; + function "*" (Left : Real_Vector; + Right : Complex_Matrix) return Complex_Vector; + function "*" (Left : Complex_Vector; + Right : Real_Matrix) return Complex_Vector; + function "*" (Left : Real_Matrix; + Right : Complex_Vector) return Complex_Vector; + function "*" (Left : Complex_Matrix; + Right : Real_Vector) return Complex_Vector; + -- Complex_Matrix scaling operations + function "*" (Left : Complex; + Right : Complex_Matrix) return Complex_Matrix; + function "*" (Left : Complex_Matrix; + Right : Complex) return Complex_Matrix; + function "/" (Left : Complex_Matrix; + Right : Complex) return Complex_Matrix; + +G.3.2 Complex Vectors and Matrices + +13 December 2012 728 + + Ada Reference Manual — 2012 Edition + + function "*" (Left : Real'Base; + Right : Complex_Matrix) return Complex_Matrix; + function "*" (Left : Complex_Matrix; + Right : Real'Base) return Complex_Matrix; + function "/" (Left : Complex_Matrix; + Right : Real'Base) return Complex_Matrix; + -- Complex_Matrix inversion and related operations + function Solve (A : Complex_Matrix; X : Complex_Vector) + return Complex_Vector; + function Solve (A, X : Complex_Matrix) return Complex_Matrix; + function Inverse (A : Complex_Matrix) return Complex_Matrix; + function Determinant (A : Complex_Matrix) return Complex; + -- Eigenvalues and vectors of a Hermitian matrix + function Eigenvalues(A : Complex_Matrix) return Real_Vector; + procedure Eigensystem(A : in Complex_Matrix; + Values : out Real_Vector; + Vectors : out Complex_Matrix); + -- Other Complex_Matrix operations + function Unit_Matrix (Order : Positive; + First_1, First_2 : Integer := 1) + return Complex_Matrix; +end Ada.Numerics.Generic_Complex_Arrays; + +The library package Numerics.Complex_Arrays is declared pure and defines the same types and +is +subprograms as Numerics.Generic_Complex_Arrays, except +systematically substituted for Real'Base, and the Real_Vector and Real_Matrix types exported by +Numerics.Real_Arrays are systematically substituted for Real_Vector and Real_Matrix, and the Complex +type exported by Numerics.Complex_Types is systematically substituted for Complex, throughout. +Nongeneric equivalents for each of the other predefined floating point types are defined similarly, with the +names Numerics.Short_Complex_Arrays, Numerics.Long_Complex_Arrays, etc. + +the predefined + +type Float + +that + +Two types are defined and exported by Numerics.Generic_Complex_Arrays. The composite type +Complex_Vector is provided to represent a vector with components of type Complex; it is defined as an +unconstrained one-dimensional array with an index of type Integer. The composite type Complex_Matrix +is provided to represent a matrix with components of type Complex; it is defined as an unconstrained, two- +dimensional array with indices of type Integer. + +The effect of the various subprograms is as described below. In many cases they are described in terms of +corresponding scalar operations in Numerics.Generic_Complex_Types. Any exception raised by those +operations is propagated by the array subprogram. Moreover, any constraints on the parameters and the +accuracy of the result for each individual component are as defined for the scalar operation. + +In the case of those operations which are defined to involve an inner product, Constraint_Error may be +raised if an intermediate result has a component outside the range of Real'Base even though the final +mathematical result would not. + +function Re (X : Complex_Vector) return Real_Vector; +function Im (X : Complex_Vector) return Real_Vector; + +Each function returns a vector of the specified Cartesian components of X. The index range of +the result is X'Range. + +procedure Set_Re (X : in out Complex_Vector; Re : in Real_Vector); +procedure Set_Im (X : in out Complex_Vector; Im : in Real_Vector); + +Each procedure replaces the specified (Cartesian) component of each of the components of X by +the value of the matching component of Re or Im; the other (Cartesian) component of each of + +729 13 December 2012 + +Complex Vectors and Matrices G.3.2 + +44/2 + +45/2 + +46/2 + +47/2 + +48/2 + +49/2 + +50/2 + +51/2 + +52/2 + +53/2 + +54/2 + +55/2 + +56/2 + +57/2 + +58/2 + +59/2 + +60/2 + + Ada Reference Manual — 2012 Edition + +the components is unchanged. Constraint_Error is raised if X'Length is not equal to Re'Length or +Im'Length. + +function Compose_From_Cartesian (Re : Real_Vector) + return Complex_Vector; +function Compose_From_Cartesian (Re, Im : Real_Vector) + return Complex_Vector; + +Each function constructs a vector of Complex results (in Cartesian representation) formed from +given vectors of Cartesian components; when only the real components are given, imaginary +components of zero are assumed. The index range of the result is Re'Range. Constraint_Error is +raised if Re'Length is not equal to Im'Length. + +function Modulus (X : Complex_Vector) return Real_Vector; +function "abs" (Right : Complex_Vector) return Real_Vector + renames Modulus; +function Argument (X : Complex_Vector) return Real_Vector; +function Argument (X : Complex_Vector; + Cycle : Real'Base) return Real_Vector; + +Each function calculates and returns a vector of the specified polar components of X or Right +using the corresponding function in numerics.generic_complex_types. The index range of the +result is X'Range or Right'Range. + +function Compose_From_Polar (Modulus, Argument : Real_Vector) + return Complex_Vector; +function Compose_From_Polar (Modulus, Argument : Real_Vector; + Cycle : Real'Base) + return Complex_Vector; + +Each function constructs a vector of Complex results (in Cartesian representation) formed from +given vectors of polar components using +in numerics.- +generic_complex_types on matching components of Modulus and Argument. The index range of +the result is Modulus'Range. Constraint_Error is raised if Modulus'Length is not equal to +Argument'Length. + +the corresponding function + +function "+" (Right : Complex_Vector) return Complex_Vector; +function "-" (Right : Complex_Vector) return Complex_Vector; + +Each operation returns the result of applying the corresponding operation in numerics.- +generic_complex_types to each component of Right. The index range of the result is +Right'Range. + +function Conjugate (X : Complex_Vector) return Complex_Vector; + +This function returns the result of applying the appropriate function Conjugate in numerics.- +generic_complex_types to each component of X. The index range of the result is X'Range. + +function "+" (Left, Right : Complex_Vector) return Complex_Vector; +function "-" (Left, Right : Complex_Vector) return Complex_Vector; + +Each operation returns the result of applying the corresponding operation in numerics.- +generic_complex_types to each component of Left and the matching component of Right. The +index range of the result is Left'Range. Constraint_Error is raised if Left'Length is not equal to +Right'Length. + +function "*" (Left, Right : Complex_Vector) return Complex; + +This operation returns the inner product of Left and Right. Constraint_Error is raised if +Left'Length is not equal to Right'Length. This operation involves an inner product. + +61/2 + +62/2 + +63/2 + +64/2 + +65/2 + +66/2 + +67/2 + +68/2 + +69/2 + +70/2 + +71/2 + +72/2 + +73/2 + +74/2 + +G.3.2 Complex Vectors and Matrices + +13 December 2012 730 + + Ada Reference Manual — 2012 Edition + +function "abs" (Right : Complex_Vector) return Real'Base; + +This operation returns the Hermitian L2-norm of Right (the square root of the inner product of +the vector with its conjugate). + +function "+" (Left : Real_Vector; + Right : Complex_Vector) return Complex_Vector; +function "+" (Left : Complex_Vector; + Right : Real_Vector) return Complex_Vector; +function "-" (Left : Real_Vector; + Right : Complex_Vector) return Complex_Vector; +function "-" (Left : Complex_Vector; + Right : Real_Vector) return Complex_Vector; + +Each operation returns the result of applying the corresponding operation in numerics.- +generic_complex_types to each component of Left and the matching component of Right. The +index range of the result is Left'Range. Constraint_Error is raised if Left'Length is not equal to +Right'Length. + +function "*" (Left : Real_Vector; Right : Complex_Vector) return Complex; +function "*" (Left : Complex_Vector; Right : Real_Vector) return Complex; + +Each operation returns the inner product of Left and Right. Constraint_Error is raised if +Left'Length is not equal to Right'Length. These operations involve an inner product. + +function "*" (Left : Complex; Right : Complex_Vector) return Complex_Vector; + +This operation returns the result of multiplying each component of Right by the complex number +Left using the appropriate operation "*" in numerics.generic_complex_types. The index range of +the result is Right'Range. + +function "*" (Left : Complex_Vector; Right : Complex) return Complex_Vector; +function "/" (Left : Complex_Vector; Right : Complex) return Complex_Vector; + +Each operation returns the result of applying the corresponding operation in numerics.- +generic_complex_types to each component of the vector Left and the complex number Right. +The index range of the result is Left'Range. + +function "*" (Left : Real'Base; + Right : Complex_Vector) return Complex_Vector; + +This operation returns the result of multiplying each component of Right by the real number Left +using the appropriate operation "*" in numerics.generic_complex_types. The index range of the +result is Right'Range. + +function "*" (Left : Complex_Vector; + Right : Real'Base) return Complex_Vector; +function "/" (Left : Complex_Vector; + Right : Real'Base) return Complex_Vector; + +Each operation returns the result of applying the corresponding operation in numerics.- +generic_complex_types to each component of the vector Left and the real number Right. The +index range of the result is Left'Range. + +function Unit_Vector (Index : Integer; + Order : Positive; + First : Integer := 1) return Complex_Vector; + +This function returns a unit vector with Order components and a lower bound of First. All +components are set to (0.0, 0.0) except for the Index component which is set to (1.0, 0.0). +Constraint_Error is raised if Index < First, Index > First + Order – 1, or if First + Order – 1 > +Integer'Last. + +75/3 + +76/2 + +77/2 + +78/2 + +79/2 + +80/2 + +81/2 + +82/2 + +83/2 + +84/2 + +85/2 + +86/2 + +87/2 + +88/2 + +89/2 + +90/2 + +731 13 December 2012 + +Complex Vectors and Matrices G.3.2 + + Ada Reference Manual — 2012 Edition + +91/2 + +92/2 + +93/2 + +94/2 + +95/2 + +96/2 + +97/2 + +98/2 + +99/2 + +100/2 + +101/2 + +102/2 + +103/2 + +104/2 + +function Re (X : Complex_Matrix) return Real_Matrix; +function Im (X : Complex_Matrix) return Real_Matrix; + +Each function returns a matrix of the specified Cartesian components of X. The index ranges of +the result are those of X. + +procedure Set_Re (X : in out Complex_Matrix; Re : in Real_Matrix); +procedure Set_Im (X : in out Complex_Matrix; Im : in Real_Matrix); + +Each procedure replaces the specified (Cartesian) component of each of the components of X by +the value of the matching component of Re or Im; the other (Cartesian) component of each of +the components is unchanged. Constraint_Error is raised if X'Length(1) is not equal to +Re'Length(1) or Im'Length(1) or if X'Length(2) is not equal to Re'Length(2) or Im'Length(2). + +function Compose_From_Cartesian (Re : Real_Matrix) + return Complex_Matrix; +function Compose_From_Cartesian (Re, Im : Real_Matrix) + return Complex_Matrix; + +Each function constructs a matrix of Complex results (in Cartesian representation) formed from +given matrices of Cartesian components; when only the real components are given, imaginary +components of zero are assumed. The index ranges of the result are those of Re. +Constraint_Error is raised if Re'Length(1) is not equal to Im'Length(1) or Re'Length(2) is not +equal to Im'Length(2). + +function Modulus (X : Complex_Matrix) return Real_Matrix; +function "abs" (Right : Complex_Matrix) return Real_Matrix + renames Modulus; +function Argument (X : Complex_Matrix) return Real_Matrix; +function Argument (X : Complex_Matrix; + Cycle : Real'Base) return Real_Matrix; + +Each function calculates and returns a matrix of the specified polar components of X or Right +using the corresponding function in numerics.generic_complex_types. The index ranges of the +result are those of X or Right. + +function Compose_From_Polar (Modulus, Argument : Real_Matrix) + return Complex_Matrix; +function Compose_From_Polar (Modulus, Argument : Real_Matrix; + Cycle : Real'Base) + return Complex_Matrix; + +Each function constructs a matrix of Complex results (in Cartesian representation) formed from +given matrices of polar components using +in numerics.- +generic_complex_types on matching components of Modulus and Argument. The index ranges +of the result are those of Modulus. Constraint_Error is raised if Modulus'Length(1) is not equal +to Argument'Length(1) or Modulus'Length(2) is not equal to Argument'Length(2). + +the corresponding function + +function "+" (Right : Complex_Matrix) return Complex_Matrix; +function "-" (Right : Complex_Matrix) return Complex_Matrix; + +Each operation returns the result of applying the corresponding operation in numerics.- +generic_complex_types to each component of Right. The index ranges of the result are those of +Right. + +function Conjugate (X : Complex_Matrix) return Complex_Matrix; + +This function returns the result of applying the appropriate function Conjugate in numerics.- +generic_complex_types to each component of X. The index ranges of the result are those of X. + +G.3.2 Complex Vectors and Matrices + +13 December 2012 732 + + Ada Reference Manual — 2012 Edition + +function Transpose (X : Complex_Matrix) return Complex_Matrix; + +This function returns the transpose of a matrix X. The first and second index ranges of the result +are X'Range(2) and X'Range(1) respectively. + +function "+" (Left, Right : Complex_Matrix) return Complex_Matrix; +function "-" (Left, Right : Complex_Matrix) return Complex_Matrix; + +Each operation returns the result of applying the corresponding operation in numerics.- +generic_complex_types to each component of Left and the matching component of Right. The +index ranges of the result are those of Left. Constraint_Error is raised if Left'Length(1) is not +equal to Right'Length(1) or Left'Length(2) is not equal to Right'Length(2). + +function "*" (Left, Right : Complex_Matrix) return Complex_Matrix; + +This operation provides the standard mathematical operation for matrix multiplication. The first +and second index ranges of the result are Left'Range(1) and Right'Range(2) respectively. +Constraint_Error is raised if Left'Length(2) is not equal to Right'Length(1). This operation +involves inner products. + +function "*" (Left, Right : Complex_Vector) return Complex_Matrix; + +This operation returns the outer product of a (column) vector Left by a (row) vector Right using +the appropriate operation "*" in numerics.generic_complex_types for computing the individual +components. The first and second index ranges of the result are Left'Range and Right'Range +respectively. + +function "*" (Left : Complex_Vector; + Right : Complex_Matrix) return Complex_Vector; + +This operation provides the standard mathematical operation for multiplication of a (row) vector +Left by a matrix Right. The index range of the (row) vector result is Right'Range(2). +Constraint_Error is raised if Left'Length is not equal to Right'Length(1). This operation involves +inner products. + +function "*" (Left : Complex_Matrix; + Right : Complex_Vector) return Complex_Vector; + +This operation provides the standard mathematical operation for multiplication of a matrix Left +by a (column) vector Right. The index range of the (column) vector result is Left'Range(1). +Constraint_Error is raised if Left'Length(2) is not equal to Right'Length. This operation involves +inner products. + +function "+" (Left : Real_Matrix; + Right : Complex_Matrix) return Complex_Matrix; +function "+" (Left : Complex_Matrix; + Right : Real_Matrix) return Complex_Matrix; +function "-" (Left : Real_Matrix; + Right : Complex_Matrix) return Complex_Matrix; +function "-" (Left : Complex_Matrix; + Right : Real_Matrix) return Complex_Matrix; + +105/2 + +106/2 + +107/2 + +108/2 + +109/2 + +110/2 + +111/2 + +112/2 + +113/2 + +114/2 + +115/2 + +116/2 + +117/2 + +Each operation returns the result of applying the corresponding operation in numerics.- +generic_complex_types to each component of Left and the matching component of Right. The +index ranges of the result are those of Left. Constraint_Error is raised if Left'Length(1) is not +equal to Right'Length(1) or Left'Length(2) is not equal to Right'Length(2). + +118/2 + +733 13 December 2012 + +Complex Vectors and Matrices G.3.2 + + Ada Reference Manual — 2012 Edition + +119/2 + +120/2 + +121/2 + +122/2 + +123/2 + +124/2 + +125/2 + +126/2 + +127/2 + +128/2 + +129/2 + +130/2 + +131/2 + +132/2 + +function "*" (Left : Real_Matrix; + Right : Complex_Matrix) return Complex_Matrix; +function "*" (Left : Complex_Matrix; + Right : Real_Matrix) return Complex_Matrix; + +Each operation provides the standard mathematical operation for matrix multiplication. The first +and second index ranges of the result are Left'Range(1) and Right'Range(2) respectively. +Constraint_Error is raised if Left'Length(2) is not equal to Right'Length(1). These operations +involve inner products. + +function "*" (Left : Real_Vector; + Right : Complex_Vector) return Complex_Matrix; +function "*" (Left : Complex_Vector; + Right : Real_Vector) return Complex_Matrix; + +Each operation returns the outer product of a (column) vector Left by a (row) vector Right using +the appropriate operation "*" in numerics.generic_complex_types for computing the individual +components. The first and second index ranges of the result are Left'Range and Right'Range +respectively. + +function "*" (Left : Real_Vector; + Right : Complex_Matrix) return Complex_Vector; +function "*" (Left : Complex_Vector; + Right : Real_Matrix) return Complex_Vector; + +Each operation provides the standard mathematical operation for multiplication of a (row) vector +Left by a matrix Right. The index range of the (row) vector result is Right'Range(2). +Constraint_Error is raised if Left'Length is not equal to Right'Length(1). These operations +involve inner products. + +function "*" (Left : Real_Matrix; + Right : Complex_Vector) return Complex_Vector; +function "*" (Left : Complex_Matrix; + Right : Real_Vector) return Complex_Vector; + +Each operation provides the standard mathematical operation for multiplication of a matrix Left +by a (column) vector Right. The index range of the (column) vector result is Left'Range(1). +Constraint_Error is raised if Left'Length(2) is not equal to Right'Length. These operations +involve inner products. + +function "*" (Left : Complex; Right : Complex_Matrix) return Complex_Matrix; + +This operation returns the result of multiplying each component of Right by the complex number +Left using the appropriate operation "*" in numerics.generic_complex_types. The index ranges +of the result are those of Right. + +function "*" (Left : Complex_Matrix; Right : Complex) return Complex_Matrix; +function "/" (Left : Complex_Matrix; Right : Complex) return Complex_Matrix; + +Each operation returns the result of applying the corresponding operation in numerics.- +generic_complex_types to each component of the matrix Left and the complex number Right. +The index ranges of the result are those of Left. + +function "*" (Left : Real'Base; + Right : Complex_Matrix) return Complex_Matrix; + +This operation returns the result of multiplying each component of Right by the real number Left +using the appropriate operation "*" in numerics.generic_complex_types. The index ranges of the +result are those of Right. + +G.3.2 Complex Vectors and Matrices + +13 December 2012 734 + + Ada Reference Manual — 2012 Edition + +function "*" (Left : Complex_Matrix; + Right : Real'Base) return Complex_Matrix; +function "/" (Left : Complex_Matrix; + Right : Real'Base) return Complex_Matrix; + +Each operation returns the result of applying the corresponding operation in numerics.- +generic_complex_types to each component of the matrix Left and the real number Right. The +index ranges of the result are those of Left. + +function Solve (A : Complex_Matrix; X : Complex_Vector) return +Complex_Vector; + +This function returns a vector Y such that X is (nearly) equal to A * Y. This is the standard +mathematical operation for solving a single set of linear equations. The index range of the result +is A'Range(2). Constraint_Error is raised if A'Length(1), A'Length(2), and X'Length are not +equal. Constraint_Error is raised if the matrix A is ill-conditioned. + +function Solve (A, X : Complex_Matrix) return Complex_Matrix; + +This function returns a matrix Y such that X is (nearly) equal to A * Y. This is the standard +mathematical operation for solving several sets of linear equations. The index ranges of the +result are A'Range(2) and X'Range(2). Constraint_Error is raised if A'Length(1), A'Length(2), +and X'Length(1) are not equal. Constraint_Error is raised if the matrix A is ill-conditioned. + +function Inverse (A : Complex_Matrix) return Complex_Matrix; + +This function returns a matrix B such that A * B is (nearly) equal to the unit matrix. The index +ranges of the result are A'Range(2) and A'Range(1). Constraint_Error is raised if A'Length(1) is +not equal to A'Length(2). Constraint_Error is raised if the matrix A is ill-conditioned. + +function Determinant (A : Complex_Matrix) return Complex; + +This function returns the determinant of the matrix A. Constraint_Error is raised if A'Length(1) +is not equal to A'Length(2). + +function Eigenvalues(A : Complex_Matrix) return Real_Vector; + +This function returns the eigenvalues of the Hermitian matrix A as a vector sorted into order +with the largest first. Constraint_Error is raised if A'Length(1) is not equal to A'Length(2). The +index range of the result is A'Range(1). Argument_Error is raised if the matrix A is not +Hermitian. + +procedure Eigensystem(A : in Complex_Matrix; + Values : out Real_Vector; + Vectors : out Complex_Matrix); + +This procedure computes both the eigenvalues and eigenvectors of the Hermitian matrix A. The +out parameter Values is the same as that obtained by calling the function Eigenvalues. The out +parameter Vectors is a matrix whose columns are the eigenvectors of the matrix A. The order of +the columns corresponds to the order of the eigenvalues. The eigenvectors are mutually +orthonormal, including when there are repeated eigenvalues. Constraint_Error is raised if +A'Length(1) is not equal to A'Length(2), or if Values'Range is not equal to A'Range(1), or if the +index ranges of the parameter Vectors are not equal to those of A. Argument_Error is raised if +the matrix A is not Hermitian. Constraint_Error is also raised in implementation-defined +circumstances if the algorithm used does not converge quickly enough. + +133/2 + +134/2 + +135/2 + +136/2 + +137/2 + +138/2 + +139/2 + +140/2 + +141/2 + +142/2 + +143/2 + +144/2 + +145/2 + +146/3 + +735 13 December 2012 + +Complex Vectors and Matrices G.3.2 + + Ada Reference Manual — 2012 Edition + +147/2 + +148/2 + +149/2 + +150/2 + +151/2 + +152/2 + +153/2 + +154/2 + +function Unit_Matrix (Order : Positive; + First_1, First_2 : Integer := 1) + return Complex_Matrix; + +This function returns a square unit matrix with Order**2 components and lower bounds of +First_1 and First_2 (for the first and second index ranges respectively). All components are set to +(0.0, 0.0) except for the main diagonal, whose components are set to (1.0, 0.0). Constraint_Error +is raised if First_1 + Order – 1 > Integer'Last or First_2 + Order – 1 > Integer'Last. + +Implementation Requirements + +Accuracy requirements for the subprograms Solve, Inverse, Determinant, Eigenvalues and Eigensystem +are implementation defined. + +For operations not involving an inner product, the accuracy requirements are those of the corresponding +operations of the type Real'Base and Complex in both the strict mode and the relaxed mode (see G.2). + +For operations involving an inner product, no requirements are specified in the relaxed mode. In the strict +mode the modulus of the absolute error of the inner product X*Y shall not exceed g*abs(X)*abs(Y) where +g is defined as + +g = X'Length * Real'Machine_Radix**(1 – Real'Model_Mantissa) + for mixed complex and real operands + +g = sqrt(2.0) * X'Length * Real'Machine_Radix**(1 – Real'Model_Mantissa) + for two complex operands + +For the L2-norm, no accuracy requirements are specified in the relaxed mode. In the strict mode the +relative error on the norm shall not exceed g / 2.0 + 3.0 * Real'Model_Epsilon where g has the definition +appropriate for two complex operands. + +155/2 + +Implementations shall document any techniques used to reduce cancellation errors such as extended +precision arithmetic. + +Documentation Requirements + +156/2 + +157/2 + +158/3 + +159/2 + +Implementation Permissions + +The nongeneric equivalent packages may, but need not, be actual instantiations of the generic package for +the appropriate predefined type. + +Although many operations are defined in terms of operations from numerics.generic_complex_types, they +need not be implemented by calling those operations provided that the effect is the same. + +Implementation Advice + +Implementations should implement the Solve and Inverse functions using established techniques. +Implementations are recommended to refine the result by performing an iteration on the residuals; if this is +done, then it should be documented. + +It is not the intention that any special provision should be made to determine whether a matrix is ill- +conditioned or not. The naturally occurring overflow (including division by zero) which will result from +executing these functions with an ill-conditioned matrix and thus raise Constraint_Error is sufficient. + +160/2 + +The test that a matrix is Hermitian should use the equality operator to compare the real components and +negation followed by equality to compare the imaginary components (see G.2.1). + +160.1/3 + +An implementation should minimize the circumstances under which the algorithm used for Eigenvalues +and Eigensystem fails to converge. + +G.3.2 Complex Vectors and Matrices + +13 December 2012 736 + + Implementations should not perform operations on mixed complex and real operands by first converting +the real operand to complex. See G.1.1. + +161/2 + +Ada Reference Manual — 2012 Edition + +737 13 December 2012 + +Complex Vectors and Matrices G.3.2 + + Ada Reference Manual — 2012 Edition + +Annex H +(normative) +High Integrity Systems + +This Annex addresses requirements for high integrity systems (including safety-critical systems and +security-critical systems). It provides facilities and specifies documentation requirements that relate to +several needs: + +• Understanding program execution; +• Reviewing object code; +• Restricting language constructs whose usage might complicate the demonstration of program + +correctness + +Execution understandability is supported by pragma Normalize_Scalars, and also by requirements for the +implementation to document the effect of a program in the presence of a bounded error or where the +language rules leave the effect unspecified. + +The pragmas Reviewable and Restrictions relate to the other requirements addressed by this Annex. + +NOTES +1 The Valid attribute (see 13.9.2) is also useful in addressing these needs, to avoid problems that could otherwise arise +from scalars that have values outside their declared range constraints. + +H.1 Pragma Normalize_Scalars + +This pragma ensures that an otherwise uninitialized scalar object is set to a predictable value, but out of +range if possible. + +The form of a pragma Normalize_Scalars is as follows: + pragma Normalize_Scalars; + +Syntax + +Post-Compilation Rules + +Pragma Normalize_Scalars is a configuration pragma. It applies to all compilation_units included in a +partition. + +If a pragma Normalize_Scalars applies, the implementation shall document the implicit initial values for +scalar subtypes, and shall identify each case in which such a value is used and is not an invalid +representation. + +Documentation Requirements + +Implementation Advice + +Whenever possible, the implicit initial values for a scalar subtype should be an invalid representation (see +13.9.1). + +NOTES +2 The initialization requirement applies to uninitialized scalar objects that are subcomponents of composite objects, to +allocated objects, and to stand-alone objects. It also applies to scalar out parameters. Scalar subcomponents of composite +out parameters are initialized to the corresponding part of the actual, by virtue of 6.4.1. + +1/2 + +2 + +3 + +4 + +4.1 + +5 + +6 + +1 + +2 + +3 + +4 + +5/2 + +6/2 + +7 + +739 13 December 2012 + +High Integrity Systems H + + Ada Reference Manual — 2012 Edition + +8 + +9 + +1 + +2 + +3 The initialization requirement does not apply to a scalar for which pragma Import has been specified, since initialization +of an imported object is performed solely by the foreign language environment (see B.1). + +4 The use of pragma Normalize_Scalars in conjunction with Pragma Restrictions(No_Exceptions) may result in +erroneous execution (see H.4). + +H.2 Documentation of Implementation Decisions + +Documentation Requirements + +The implementation shall document the range of effects for each situation that the language rules identify +as either a bounded error or as having an unspecified effect. If the implementation can constrain the effects +of erroneous execution for a given construct, then it shall document such constraints. The documentation +might be provided either independently of any compilation unit or partition, or as part of an annotated +listing for a given unit or partition. See also 1.1.3, and 1.1.2. + +NOTES +5 Among the situations to be documented are the conventions chosen for parameter passing, the methods used for the +management of run-time storage, and the method used to evaluate numeric expressions if this involves extended range or +extra precision. + +H.3 Reviewable Object Code + +1 + +Object code review and validation are supported by pragmas Reviewable and Inspection_Point. + +H.3.1 Pragma Reviewable + +This pragma directs the implementation to provide information to facilitate analysis and review of a +program's object code, in particular to allow determination of execution time and storage usage and to +identify the correspondence between the source and object programs. + +The form of a pragma Reviewable is as follows: + pragma Reviewable; + +Syntax + +Post-Compilation Rules + +Pragma Reviewable is a configuration pragma. It applies to all compilation_units included in a partition. + +Implementation Requirements + +The implementation shall provide the following information for any compilation unit to which such a +pragma applies: + +• Where compiler-generated run-time checks remain; +• An identification of any construct with a language-defined check that is recognized prior to run +time as certain to fail if executed (even if the generation of run-time checks has been +suppressed); + +• For each read of a scalar object, an identification of the read as either “known to be initialized,” + +or “possibly uninitialized,” independent of whether pragma Normalize_Scalars applies; + +• Where run-time support routines are implicitly invoked; + +1 + +2 + +3 + +4 + +5 + +6 + +7 + +8/2 + +9 + +H.1 Pragma Normalize_Scalars + +13 December 2012 740 + + Ada Reference Manual — 2012 Edition + +• An object code listing, including: + +• Machine instructions, with relative offsets; + +• Where each data object is stored during its lifetime; + +• Correspondence with the source program, including an identification of the code produced + +per declaration and per statement. + +• An identification of each construct for which the implementation detects the possibility of + +erroneous execution; + +• For each subprogram, block, task, or other construct implemented by reserving and subsequently +freeing an area on a run-time stack, an identification of the length of the fixed-size portion of the +area and an indication of whether the non-fixed size portion is reserved on the stack or in a +dynamically-managed storage region. + +The implementation shall provide the following information for any partition to which the pragma applies: + +• An object code listing of the entire partition, including initialization and finalization code as well +as run-time system components, and with an identification of those instructions and data that +will be relocated at load time; + +• A description of the run-time model relevant to the partition. + +The implementation shall provide control- and data-flow information, both within each compilation unit +and across the compilation units of the partition. + +Implementation Advice + +The implementation should provide the above information in both a human-readable and machine-readable +form, and should document the latter so as to ease further processing by automated tools. + +Object code listings should be provided both in a symbolic format and also in an appropriate numeric +format (such as hexadecimal or octal). + +NOTES +6 The order of elaboration of library units will be documented even in the absence of pragma Reviewable (see 10.2). + +H.3.2 Pragma Inspection_Point + +An occurrence of a pragma Inspection_Point identifies a set of objects each of whose values is to be +available at the point(s) during program execution corresponding to the position of the pragma in the +compilation unit. The purpose of such a pragma is to facilitate code validation. + +The form of a pragma Inspection_Point is as follows: + pragma Inspection_Point[(object_name {, object_name})]; + +Syntax + +Legality Rules + +A pragma Inspection_Point is allowed wherever a declarative_item or statement is allowed. Each +object_name shall statically denote the declaration of an object. + +10 + +11 + +12 + +13 + +14 + +15 + +16 + +17 + +18 + +18.1 + +19 + +20 + +21 + +1 + +2 + +3 + +4 + +An inspection point is a point in the object code corresponding to the occurrence of a pragma Inspection_- +Point in the compilation unit. An object is inspectable at an inspection point if the corresponding pragma + +5/2 + +Static Semantics + +741 13 December 2012 + +Pragma Reviewable H.3.1 + + Ada Reference Manual — 2012 Edition + +Inspection_Point either has an argument denoting that object, or has no arguments and the declaration of +the object is visible at the inspection point. + +Execution of a pragma Inspection_Point has no effect. + +Dynamic Semantics + +Reaching an inspection point is an external interaction with respect to the values of the inspectable objects +at that point (see 1.1.3). + +Implementation Requirements + +For each inspection point, the implementation shall identify a mapping between each inspectable object +and the machine resources (such as memory locations or registers) from which the object's value can be +obtained. + +Documentation Requirements + +NOTES +7 The implementation is not allowed to perform “dead store elimination” on the last assignment to a variable prior to a +point where the variable is inspectable. Thus an inspection point has the effect of an implicit read of each of its inspectable +objects. + +8 Inspection points are useful in maintaining a correspondence between the state of the program in source code terms, and +the machine state during the program's execution. Assertions about the values of program objects can be tested in machine +terms at inspection points. Object code between inspection points can be processed by automated tools to verify programs +mechanically. + +9 The identification of the mapping from source program objects to machine resources is allowed to be in the form of an +annotated object listing, in human-readable or tool-processable form. + +6 + +7 + +8 + +9/2 + +10 + +11 + +H.4 High Integrity Restrictions + +1/3 + +This subclause defines restrictions that can be used with pragma Restrictions (see 13.12); these facilitate +the demonstration of program correctness by allowing tailored versions of the run-time system. + +2/2 + +3/2 + +4 + +5 + +6 + +7 + +This paragraph was deleted. + +The following restriction_identifiers are language defined: + +Static Semantics + +Tasking-related restriction: + +No_Protected_Types + +There are no declarations of protected types or protected objects. + +Memory-management related restrictions: + +No_Allocators + +There are no occurrences of an allocator. + +8/1 + +No_Local_Allocators + +Allocators are prohibited in subprograms, generic subprograms, tasks, and entry bodies. + +8.1/3 + +No_Anonymous_Allocators + +There are no allocators of anonymous access types. + +8.2/3 + +No_Coextensions + +There are no coextensions. See 3.10.2. + +H.3.2 Pragma Inspection_Point + +13 December 2012 742 + + + + + + + Ada Reference Manual — 2012 Edition + +No_Access_Parameter_Allocators + +Allocators are not permitted as the actual parameter to an access parameter. See 6.1. + +This paragraph was deleted. + +Immediate_Reclamation + +Except for storage occupied by objects created by allocators and not deallocated via +unchecked deallocation, any storage reserved at run time for an object is immediately +reclaimed when the object no longer exists. + +Exception-related restriction: + +No_Exceptions + +Raise_statements and exception_handlers are not allowed. No language-defined run-time +checks are generated; however, a run-time check performed automatically by the hardware +is permitted. + +Other restrictions: + +No_Floating_Point + +Uses of predefined floating point types and operations, and declarations of new floating +point types, are not allowed. + +No_Fixed_Point + +Uses of predefined fixed point types and operations, and declarations of new fixed point +types, are not allowed. + +This paragraph was deleted. + +No_Access_Subprograms + +The declaration of access-to-subprogram types is not allowed. + +No_Unchecked_Access + +The Unchecked_Access attribute is not allowed. + +No_Dispatch Occurrences of T'Class are not allowed, for any (tagged) subtype T. + +No_IO + +Semantic dependence on any of the library units Sequential_IO, Direct_IO, Text_IO, +Wide_Text_IO, Wide_Wide_Text_IO, or Stream_IO is not allowed. + +No_Delay Delay_Statements and semantic dependence on package Calendar are not allowed. + +No_Recursion + +As part of the execution of a subprogram, the same subprogram is not invoked. + +No_Reentrancy + +During the execution of a subprogram by a task, no other task invokes the same +subprogram. + +An implementation of this Annex shall support: + +Implementation Requirements + +• +• + +• +• + +the restrictions defined in this subclause; and + +following + +the +No_Implicit_Heap_Allocation, No_Standard_Allocators_After_Elaboration; and + +in D.7: No_Task_Hierarchy, No_Abort_Statement, + +restrictions defined + +the pragma Profile(Ravenscar); and + +the following uses of restriction_parameter_identifiers defined in D.7, which are checked prior +to program execution: + +• Max_Task_Entries => 0, + +8.3/3 + +9/2 + +10 + +11 + +12 + +13 + +14 + +15 + +16/2 + +17 + +18 + +19 + +20/2 + +21 + +22 + +23 + +23.1/2 + +23.2/2 + +23.3/3 + +23.4/2 + +23.5/2 + +23.6/2 + +743 13 December 2012 + +High Integrity Restrictions H.4 + + + + + + + + + + + + + Ada Reference Manual — 2012 Edition + +• Max_Asynchronous_Select_Nesting => 0, and + +• Max_Tasks => 0. + +If an implementation supports pragma Restrictions for a particular argument, then except for the +restrictions No_Unchecked_Deallocation, No_Unchecked_Conversion, No_Access_Subprograms, +No_Unchecked_Access, No_Specification_of_Aspect, No_Use_of_Attribute, No_Use_of_Pragma, and +the equivalent use of No_Dependence, the associated restriction applies to the run-time system. + +If a pragma Restrictions(No_Exceptions) is specified, the implementation shall document the effects of all +constructs where language-defined checks are still performed automatically (for example, an overflow +check performed by the processor). + +Documentation Requirements + +Erroneous Execution + +Program execution is erroneous if pragma Restrictions(No_Exceptions) has been specified and the +conditions arise under which a generated language-defined run-time check would fail. + +Program execution is erroneous if pragma Restrictions(No_Recursion) has been specified and a +subprogram is invoked as part of its own execution, or if pragma Restrictions(No_Reentrancy) has been +specified and during the execution of a subprogram by a task, another task invokes the same subprogram. + +NOTES +10 Uses of restriction_parameter_identifier No_Dependence defined in 13.12.1: No_Dependence => Ada.Unchecked_- +Deallocation and No_Dependence => Ada.Unchecked_Conversion may be appropriate for high-integrity systems. Other +uses of No_Dependence can also be appropriate for high-integrity systems. + +23.7/2 + +23.8/2 + +24/3 + +25 + +26 + +27 + +28/2 + +H.5 Pragma Detect_Blocking + +1/2 + +The following pragma forces an implementation to detect potentially blocking operations within a +protected operation. + +2/2 + +3/2 + +The form of a pragma Detect_Blocking is as follows: + pragma Detect_Blocking; + +Syntax + +4/2 + +A pragma Detect_Blocking is a configuration pragma. + +Post-Compilation Rules + +Dynamic Semantics + +5/2 + +An implementation is required to detect a potentially blocking operation within a protected operation, and +to raise Program_Error (see 9.5.1). + +Implementation Permissions + +6/2 + +7/2 + +An implementation is allowed to reject a compilation_unit if a potentially blocking operation is present +directly within an entry_body or the body of a protected subprogram. + +NOTES +11 An operation that causes a task to be blocked within a foreign language domain is not defined to be potentially +blocking, and need not be detected. + +H.4 High Integrity Restrictions + +13 December 2012 744 + + Ada Reference Manual — 2012 Edition + +H.6 Pragma Partition_Elaboration_Policy + +This subclause defines a pragma for user control over elaboration policy. + +The form of a pragma Partition_Elaboration_Policy is as follows: + pragma Partition_Elaboration_Policy (policy_identifier); + +Syntax + +The policy_identifier shall be either Sequential, Concurrent or an implementation-defined identifier. + +Post-Compilation Rules + +A pragma Partition_Elaboration_Policy is a configuration pragma. It specifies the elaboration policy for a +partition. At most one elaboration policy shall be specified for a partition. + +If the Sequential policy is specified for a partition, then pragma Restrictions (No_Task_Hierarchy) shall +also be specified for the partition. + +Dynamic Semantics + +Notwithstanding what this International Standard says elsewhere, this pragma allows partition elaboration +rules concerning task activation and interrupt attachment to be changed. If the policy_identifier is +Concurrent, or if there is no pragma Partition_Elaboration_Policy defined for the partition, then the rules +defined elsewhere in this Standard apply. + +If the partition elaboration policy is Sequential, then task activation and interrupt attachment are +performed in the following sequence of steps: + +• The activation of all library-level tasks and the attachment of interrupt handlers are deferred + +until all library units are elaborated. + +• The interrupt handlers are attached by the environment task. +• The environment task is suspended while the library-level tasks are activated. +• The environment task executes the main subprogram (if any) concurrently with these executing + +tasks. + +If several dynamic interrupt handler attachments for the same interrupt are deferred, then the most recent +call of Attach_Handler or Exchange_Handler determines which handler is attached. + +If any deferred task activation fails, Tasking_Error is raised at the beginning of the sequence of statements +of the body of the environment task prior to calling the main subprogram. + +If the partition elaboration policy is Sequential and the Environment task becomes permanently blocked +during elaboration, then the partition is deadlocked and it is recommended that the partition be +immediately terminated. + +Implementation Advice + +1/3 + +2/2 + +3/2 + +4/2 + +5/2 + +6/3 + +7/2 + +8/2 + +9/2 + +10/2 + +11/2 + +12/2 + +13/2 + +14/2 + +15/3 + +If the partition elaboration policy is Sequential and any task activation fails, then an implementation may +immediately terminate the active partition to mitigate the hazard posed by continuing to execute with a +subset of the tasks being active. + +16/3 + +Implementation Permissions + +745 13 December 2012 + +Pragma Partition_Elaboration_Policy H.6 + + Ada Reference Manual — 2012 Edition + +17/2 + +NOTES +12 If any deferred task activation fails, the environment task is unable to handle the Tasking_Error exception and +completes immediately. By contrast, if the partition elaboration policy is Concurrent, then this exception could be handled +within a library unit. + +H.6 Pragma Partition_Elaboration_Policy + +13 December 2012 746 + + Ada Reference Manual — 2012 Edition + +Annex J +(normative) +Obsolescent Features + +This Annex contains descriptions of features of the language whose functionality is largely redundant with +other features defined by this International Standard. Use of these features is not recommended in newly +features can be prevented by using pragma Restrictions +written programs. Use of +(No_Obsolescent_Features), see 13.12.1. + +these + +1/2 + +J.1 Renamings of Library Units + +The following library_unit_renaming_declarations exist: + +Static Semantics + +with Ada.Unchecked_Conversion; +generic function Unchecked_Conversion renames Ada.Unchecked_Conversion; +with Ada.Unchecked_Deallocation; +generic procedure Unchecked_Deallocation renames Ada.Unchecked_Deallocation; +with Ada.Sequential_IO; +generic package Sequential_IO renames Ada.Sequential_IO; +with Ada.Direct_IO; +generic package Direct_IO renames Ada.Direct_IO; +with Ada.Text_IO; +package Text_IO renames Ada.Text_IO; +with Ada.IO_Exceptions; +package IO_Exceptions renames Ada.IO_Exceptions; +with Ada.Calendar; +package Calendar renames Ada.Calendar; +with System.Machine_Code; +package Machine_Code renames System.Machine_Code; -- If supported. + +The implementation shall allow the user to replace these renamings. + +Implementation Requirements + +J.2 Allowed Replacements of Characters + +Syntax + +The following replacements are allowed for the vertical line, number sign, and quotation mark +characters: + +• A vertical line character (|) can be replaced by an exclamation mark (!) where used as a + +delimiter. + +• The number sign characters (#) of a based_literal can be replaced by colons (:) provided + +that the replacement is done for both occurrences. + +• The quotation marks (") used as string brackets at both ends of a string literal can be +replaced by percent signs (%) provided that the enclosed sequence of characters contains no +quotation mark, and provided that both string brackets are replaced. Any percent sign +within the sequence of characters shall then be doubled and each such doubled percent sign +is interpreted as a single percent sign character value. + +1 + +2 + +3 + +4 + +5 + +6 + +7 + +8 + +9 + +10 + +1 + +2 + +3 + +4 + +747 13 December 2012 + +Obsolescent Features J + + 5 + +1 + +2 + +3 + +4 + +5 + +6 + +7 + +8 + +9 + +10 + +Ada Reference Manual — 2012 Edition + +These replacements do not change the meaning of the program. + +J.3 Reduced Accuracy Subtypes + +A digits_constraint may be used to define a floating point subtype with a new value for its requested +decimal precision, as reflected by its Digits attribute. Similarly, a delta_constraint may be used to define +an ordinary fixed point subtype with a new value for its delta, as reflected by its Delta attribute. + +delta_constraint ::= delta static_expression [range_constraint] + +Syntax + +The expression of a delta_constraint is expected to be of any real type. + +Name Resolution Rules + +The expression of a delta_constraint shall be static. + +Legality Rules + +For a subtype_indication with a delta_constraint, the subtype_mark shall denote an ordinary fixed point +subtype. + +For a subtype_indication with a digits_constraint, the subtype_mark shall denote either a decimal fixed +point subtype or a floating point subtype (notwithstanding the rule given in 3.5.9 that only allows a +decimal fixed point subtype). + +Static Semantics + +A subtype_indication with a subtype_mark that denotes an ordinary fixed point subtype and a +delta_constraint defines an ordinary fixed point subtype with a delta given by the value of the expression +of the delta_constraint. If the delta_constraint includes a range_constraint, then the ordinary fixed point +subtype is constrained by the range_constraint. + +A subtype_indication with a subtype_mark that denotes a floating point subtype and a digits_constraint +defines a floating point subtype with a requested decimal precision (as reflected by its Digits attribute) +given by the value of the expression of the digits_constraint. If the digits_constraint includes a range_- +constraint, then the floating point subtype is constrained by the range_constraint. + +Dynamic Semantics + +A delta_constraint is compatible with an ordinary fixed point subtype if the value of the expression is no +less than the delta of the subtype, and the range_constraint, if any, is compatible with the subtype. + +A digits_constraint is compatible with a floating point subtype if the value of the expression is no greater +than the requested decimal precision of the subtype, and the range_constraint, if any, is compatible with +the subtype. + +11 + +The elaboration of a delta_constraint consists of the elaboration of the range_constraint, if any. + +J.2 Allowed Replacements of Characters + +13 December 2012 748 + + Ada Reference Manual — 2012 Edition + +J.4 The Constrained Attribute + +For every private subtype S, the following attribute is defined: + +Static Semantics + +S'Constrained + +Yields the value False if S denotes an unconstrained nonformal private subtype with +discriminants; also yields the value False if S denotes a generic formal private subtype, and +the associated actual subtype is either an unconstrained subtype with discriminants or an +unconstrained array subtype; yields the value True otherwise. The value of this attribute is +of the predefined subtype Boolean. + +J.5 ASCII + +The following declaration exists in the declaration of package Standard: + +Static Semantics + +package ASCII is + -- Control characters: + NUL : constant Character := nul; +SOH : constant Character := soh; + STX : constant Character := stx; +ETX : constant Character := etx; +ENQ : constant Character := enq; + EOT : constant Character := eot; + ACK : constant Character := ack; BEL : constant Character := bel; +HT : constant Character := ht; + BS : constant Character := bs; +VT : constant Character := vt; + LF : constant Character := lf; +CR : constant Character := cr; + FF : constant Character := ff; +SI : constant Character := si; + SO : constant Character := so; +DC1 : constant Character := dc1; + DLE : constant Character := dle; + DC2 : constant Character := dc2; DC3 : constant Character := dc3; + DC4 : constant Character := dc4; NAK : constant Character := nak; + SYN : constant Character := syn; ETB : constant Character := etb; + CAN : constant Character := can; EM : constant Character := em; + SUB : constant Character := sub; ESC : constant Character := esc; +GS : constant Character := gs; + FS : constant Character := fs; +US : constant Character := us; + RS : constant Character := rs; + DEL : constant Character := del; + -- Other characters: + Exclam : constant Character:= '!'; Quotation : constant Character:= '"'; + Sharp : constant Character:= '#'; Dollar : constant Character:= '$'; + Percent : constant Character:= '%'; Ampersand : constant Character:= '&'; + Colon : constant Character:= ':'; Semicolon : constant Character:= ';'; + Query : constant Character:= '?'; At_Sign : constant Character:= '@'; + L_Bracket: constant Character:= '['; Back_Slash: constant Character:= '\'; + R_Bracket: constant Character:= ']'; Circumflex: constant Character:= '^'; + Underline: constant Character:= '_'; Grave : constant Character:= '`'; + L_Brace : constant Character:= '{'; Bar : constant Character:= '|'; + R_Brace : constant Character:= '}'; Tilde : constant Character:= '~'; + -- Lower case letters: + LC_A: constant Character:= 'a'; + ... + LC_Z: constant Character:= 'z'; +end ASCII; + +1 + +2 + +1 + +2 + +3 + +4 + +5 + +6 + +7 + +8 + +9 + +749 13 December 2012 + +The Constrained Attribute J.4 + + + 1 + +2 + +1 + +2 + +1 + +2 + +3 + +4 + +5 + +6 + +7 + +8 + +9 + +10 + +Ada Reference Manual — 2012 Edition + +J.6 Numeric_Error + +The following declaration exists in the declaration of package Standard: +Numeric_Error : exception renames Constraint_Error; + +Static Semantics + +J.7 At Clauses + +Syntax +at_clause ::= for direct_name use at expression; + +Static Semantics + +An at_clause of the form “for x use at y;” is equivalent to an attribute_definition_clause of the form “for +x'Address use y;”. + +J.7.1 Interrupt Entries + +Implementations are permitted to allow the attachment of task entries to interrupts via the address clause. +Such an entry is referred to as an interrupt entry. + +The address of the task entry corresponds to a hardware interrupt in an implementation-defined manner. +(See Ada.Interrupts.Reference in C.3.2.) + +The following attribute is defined: + +For any task entry X: + +Static Semantics + +X'Address + +For a task entry whose address is specified (an interrupt entry), the value refers to the +corresponding hardware interrupt. For such an entry, as for any other task entry, the +meaning of this value is implementation defined. The value of this attribute is of the type of +the subtype System.Address. + +Address may be specified for single entries via an attribute_definition_clause. + +Dynamic Semantics + +As part of the initialization of a task object, the address clause for an interrupt entry is elaborated, which +evaluates the expression of the address clause. A check is made that the address specified is associated +with some interrupt to which a task entry may be attached. If this check fails, Program_Error is raised. +Otherwise, the interrupt entry is attached to the interrupt associated with the specified address. + +Upon finalization of the task object, the interrupt entry, if any, is detached from the corresponding +interrupt and the default treatment is restored. + +While an interrupt entry is attached to an interrupt, the interrupt is reserved (see C.3). + +An interrupt delivered to a task entry acts as a call to the entry issued by a hardware task whose priority is +in the System.Interrupt_Priority range. It is implementation defined whether the call is performed as an +ordinary entry call, a timed entry call, or a conditional entry call; which kind of call is performed can +depend on the specific interrupt. + +J.6 Numeric_Error + +13 December 2012 750 + + + Ada Reference Manual — 2012 Edition + +It is a bounded error to evaluate E'Caller (see C.7.1) in an accept_statement for an interrupt entry. The +possible effects are the same as for calling Current_Task from an entry body. + +Bounded (Run-Time) Errors + +The implementation shall document to which interrupts a task entry may be attached. + +Documentation Requirements + +The implementation shall document whether the invocation of an interrupt entry has the effect of an +ordinary entry call, conditional call, or a timed call, and whether the effect varies in the presence of +pending interrupts. + +The support for this subclause is optional. + +Implementation Permissions + +Interrupts to which the implementation allows a task entry to be attached may be designated as reserved +for the entire duration of program execution; that is, not just when they have an interrupt entry attached to +them. + +11 + +12 + +13 + +14 + +15 + +Interrupt entry calls may be implemented by having the hardware execute directly the appropriate +accept_statement. Alternatively, the implementation is allowed to provide an internal interrupt handler to +simulate the effect of a normal task calling the entry. + +16/1 + +The implementation is allowed to impose restrictions on the specifications and bodies of tasks that have +interrupt entries. + +It is implementation defined whether direct calls (from the program) to interrupt entries are allowed. + +If a select_statement contains both a terminate_alternative and an accept_alternative for an interrupt +entry, then an implementation is allowed to impose further requirements for the selection of the +terminate_alternative in addition to those given in 9.3. + +NOTES +1 Queued interrupts correspond to ordinary entry calls. Interrupts that are lost if not immediately processed correspond to +conditional entry calls. It is a consequence of the priority rules that an accept_statement executed in response to an +interrupt can be executed with the active priority at which the hardware generates the interrupt, taking precedence over +lower priority tasks, without a scheduling action. + +17 + +18 + +19 + +20/1 + +2 Control information that is supplied upon an interrupt can be passed to an associated interrupt entry as one or more +parameters of mode in. + +21 + +Example of an interrupt entry: + +Examples + +task Interrupt_Handler is + entry Done; + for Done'Address use +Ada.Interrupts.Reference(Ada.Interrupts.Names.Device_Done); +end Interrupt_Handler; + +22 + +23 + +751 13 December 2012 + +Interrupt Entries J.7.1 + + Ada Reference Manual — 2012 Edition + +J.8 Mod Clauses + +mod_clause ::= at mod static_expression; + +Syntax + +A record_representation_clause of the form: + +Static Semantics + +for r use + record at mod a; + ... + end record; + +is equivalent to: + +for r'Alignment use a; +for r use + record + ... + end record; + +J.9 The Storage_Size Attribute + +For any task subtype T, the following attribute is defined: + +Static Semantics + +T'Storage_Size + +Denotes an implementation-defined value of type universal_integer representing the +number of storage elements reserved for a task of the subtype T. + +Storage_Size may be specified for a task first subtype that is not an interface via an +attribute_definition_clause. When the attribute is specified, the Storage_Size aspect is +specified to be the value of the given expression. + +1 + +2 + +3/3 + +4 + +5 + +1 + +2 + +3/3 + +J.10 Specific Suppression of Checks + +1/2 + +Pragma Suppress can be used to suppress checks on specific entities. + +2/2 + +3/2 + +4/2 + +5/2 + +6/2 + +The form of a specific Suppress pragma is as follows: + pragma Suppress(identifier, [On =>] name); + +Syntax + +Legality Rules + +The identifier shall be the name of a check (see 11.5). The name shall statically denote some entity. + +For a specific Suppress pragma that is immediately within a package_specification, the name shall +denote an entity (or several overloaded subprograms) declared immediately within the package_- +specification. + +A specific Suppress pragma applies to the named check from the place of the pragma to the end of the +innermost enclosing declarative region, or, if the pragma is given in a package_specification, to the end +of the scope of the named entity. The pragma applies only to the named entity, or, for a subtype, on + +Static Semantics + +J.8 Mod Clauses + +13 December 2012 752 + + + + Ada Reference Manual — 2012 Edition + +objects and values of its type. A specific Suppress pragma suppresses the named check for any entities to +which it applies (see 11.5). Which checks are associated with a specific entity is not defined by this +International Standard. + +An implementation is allowed to place restrictions on specific Suppress pragmas. + +NOTES +3 An implementation may support a similar On parameter on pragma Unsuppress (see 11.5). + +Implementation Permissions + +J.11 The Class Attribute of Untagged Incomplete Types + +Static Semantics + +For the first subtype S of a type T declared by an incomplete_type_declaration that is not tagged, the +following attribute is defined: + +S'Class + +Denotes the first subtype of the incomplete class-wide type rooted at T. The completion of +T shall declare a tagged type. Such an attribute reference shall occur in the same library unit +as the incomplete_type_declaration. + +J.12 Pragma Interface + +Syntax +In addition to an identifier, the reserved word interface is allowed as a pragma name, to provide +compatibility with a prior edition of this International Standard. + +7/2 + +8/2 + +1/2 + +2/2 + +1/2 + +J.13 Dependence Restriction Identifiers + +The following restrictions involve dependence on specific language-defined units. The more general +restriction No_Dependence (see 13.12.1) should be used for this purpose. + +1/2 + +The following restriction_identifiers exist: + +No_Asynchronous_Control + +Static Semantics + +Semantic dependence on the predefined package Asynchronous_Task_Control is not +allowed. + +No_Unchecked_Conversion + +Semantic dependence on the predefined generic function Unchecked_Conversion is not +allowed. + +No_Unchecked_Deallocation + +Semantic dependence on the predefined generic procedure Unchecked_Deallocation is not +allowed. + +2/2 + +3/2 + +4/2 + +5/2 + +753 13 December 2012 + +Specific Suppression of Checks J.10 + + + + + Ada Reference Manual — 2012 Edition + +J.14 Character and Wide_Character Conversion Functions + +The following declarations exist in the declaration of package Ada.Characters.Handling: + +Static Semantics + + function Is_Character (Item : in Wide_Character) return Boolean + renames Conversions.Is_Character; + function Is_String (Item : in Wide_String) return Boolean + renames Conversions.Is_String; + function To_Character (Item : in Wide_Character; + Substitute : in Character := ' ') + return Character + renames Conversions.To_Character; + function To_String (Item : in Wide_String; + Substitute : in Character := ' ') + return String + renames Conversions.To_String; + function To_Wide_Character (Item : in Character) return Wide_Character + renames Conversions.To_Wide_Character; + function To_Wide_String (Item : in String) return Wide_String + renames Conversions.To_Wide_String; + +1/2 + +2/2 + +3/2 + +4/2 + +5/2 + +6/2 + +J.15 Aspect-related Pragmas + +1/3 + +Pragmas can be used as an alternative to aspect_specifications to specify certain aspects. + +J.15.1 Pragma Inline + +1/3 + +2/3 + +The form of a pragma Inline, which is a program unit pragma (see 10.1.5), is as follows: + pragma Inline (name{, name}); + +Syntax + +3/3 + +The pragma shall apply to one or more callable entities or generic subprograms. + +Legality Rules + +4/3 + +Pragma Inline specifies that the Inline aspect (see 6.3.2) for each entity denoted by each name given in +the pragma has the value True. + +Static Semantics + +Implementation Permissions + +5/3 + +6/3 + +An implementation may allow a pragma Inline that has an argument which is a direct_name denoting a +subprogram_body of the same declarative_part. + +NOTES +4 The name in a pragma Inline may denote more than one entity in the case of overloading. Such a pragma applies to all +of the denoted entities. + +J.14 Character and Wide_Character Conversion Functions + +13 December 2012 754 + + Ada Reference Manual — 2012 Edition + +J.15.2 Pragma No_Return + +The form of a pragma No_Return, which is a representation pragma (see 13.1), is as follows: + pragma No_Return (procedure_local_name{, procedure_local_name}); + +Syntax + +Each procedure_local_name shall denote one or more procedures or generic procedures. The +procedure_local_name shall not denote a null procedure nor an instance of a generic unit. + +Legality Rules + +1/3 + +2/3 + +3/3 + +Pragma No_Return specifies that the No_Return aspect (see 6.5.1) for each procedure denoted by each +local_name given in the pragma has the value True. + +4/3 + +Static Semantics + +J.15.3 Pragma Pack + +The form of a pragma Pack, which is a representation pragma (see 13.1), is as follows: + pragma Pack (first_subtype_local_name); + +Syntax + +The first_subtype_local_name of a pragma Pack shall denote a composite subtype. + +Legality Rules + +Pragma Pack specifies that the Pack aspect (see 13.2) for the type denoted by first_subtype_local_name +has the value True. + +Static Semantics + +J.15.4 Pragma Storage_Size + +Syntax +The form of a pragma Storage_Size is as follows: + pragma Storage_Size (expression); + +A pragma Storage_Size is allowed only immediately within a task_definition. + +The expression of a pragma Storage_Size is expected to be of any integer type. + +Name Resolution Rules + +The pragma Storage_Size sets the Storage_Size aspect (see 13.3) of the type defined by the immediately +enclosing task_definition to the value of the expression of the pragma. + +Static Semantics + +1/3 + +2/3 + +3/3 + +4/3 + +1/3 + +2/3 + +3/3 + +4/3 + +5/3 + +755 13 December 2012 + +Pragma No_Return J.15.2 + + Ada Reference Manual — 2012 Edition + +J.15.5 Interfacing Pragmas + +1/3 + +2/3 + +3/3 + +4/3 + +5/3 + +6/3 + +7/3 + +8/3 + +9/3 + +10/3 + +11/3 + +12/3 + +13/3 + +14/3 + +15/3 + +Syntax +An interfacing pragma is a representation pragma that is one of the pragmas Import, Export, or +Convention. Their forms are as follows: + pragma Import( + [Convention =>] convention_identifier, [Entity =>] local_name + [, [External_Name =>] external_name_string_expression] + [, [Link_Name =>] link_name_string_expression]); + + pragma Export( + [Convention =>] convention_identifier, [Entity =>] local_name + [, [External_Name =>] external_name_string_expression] + [, [Link_Name =>] link_name_string_expression]); + + pragma Convention([Convention =>] convention_identifier,[Entity =>] local_name); + +For pragmas Import and Export, the argument for Link_Name shall not be given without the +pragma_argument_identifier unless the argument for External_Name is given. + + The expected type for an external_name_string_expression and a link_name_string_expression in an +interfacing pragma is String. + +Name Resolution Rules + +Legality Rules + +The convention_identifier of an interfacing pragma shall be the name of a convention (see B.1). + +A pragma Import shall be the completion of a declaration. Notwithstanding any rule to the contrary, a +pragma Import may serve as the completion of any kind of (explicit) declaration if supported by an +implementation for that kind of declaration. If a completion is a pragma Import, then it shall appear in the +same declarative_part, package_specification, task_definition, or protected_definition as the declaration. +For a library unit, it shall appear in the same compilation, before any subsequent compilation_units other +than pragmas. If the local_name denotes more than one entity, then the pragma Import is the completion +of all of them. + +The external_name_string_expression and link_name_string_expression of a pragma Import or Export +shall be static. + +The local_name of each of these pragmas shall denote a declaration that may have the similarly named +aspect specified. + +Static Semantics + +An interfacing pragma specifies various aspects of the entity denoted by the local_name as follows: + +• The Convention aspect (see B.1) is convention_identifier. +• A pragma Import specifies that the Import aspect (see B.1) is True. +• A pragma Export specifies that the Export aspect (see B.1) is True. +• For both pragma Import and Export, if an external name is given in the pragma, the +External_Name aspect (see B.1) is specified to be external_name_string_expression. If a link +name is given in the pragma, the Link_Name aspect (see B.1) is specified to be the +link_name_string_expression. + +J.15.5 Interfacing Pragmas + +13 December 2012 756 + + Ada Reference Manual — 2012 Edition + +J.15.6 Pragma Unchecked_Union + +Syntax + +The form of a pragma Unchecked_Union, which is a representation pragma (see 13.1), is as follows: + pragma Unchecked_Union (first_subtype_local_name); + +first_subtype_local_name of a pragma Unchecked_Union shall denote an unconstrained + +The +discriminated record subtype having a variant_part. + +Legality Rules + +1/3 + +2/3 + +3/3 + +A pragma Unchecked_Union specifies that the Unchecked_Union aspect (see B.3.3) for the type denoted +by first_subtype_local_name has the value True. + +4/3 + +Static Semantics + +J.15.7 Pragmas Interrupt_Handler and Attach_Handler + +Syntax + +The form of a pragma Interrupt_Handler is as follows: + pragma Interrupt_Handler (handler_name); + +The form of a pragma Attach_Handler is as follows: + pragma Attach_Handler (handler_name, expression); + +Name Resolution Rules + +For the Interrupt_Handler and Attach_Handler pragmas, the handler_name shall resolve to denote a +protected procedure with a parameterless profile. + +1/3 + +2/3 + +3/3 + +4/3 + +5/3 + +For the Attach_Handler pragma, the expected type for the expression is Interrupts.Interrupt_Id (see C.3.2). + +6/3 + +Legality Rules + +7/3 + +8/3 + +The Attach_Handler and Interrupt_Handler pragmas are only allowed immediately within the +protected_definition where +is declared. The corresponding +protected_type_declaration or single_protected_declaration shall be a library-level declaration, and shall +not be declared within a generic body. In addition to the places where Legality Rules normally apply (see +12.3), these rules also apply in the private part of an instance of a generic unit. + +the corresponding + +subprogram + +Static Semantics + +For an implementation that supports Annex C, a pragma Interrupt_Handler specifies the Interrupt_Handler +aspect (see C.3.1) for the protected procedure handler_name to have the value True. For an +implementation that supports Annex C, a pragma Attach_Handler specifies the Attach_Handler aspect (see +C.3.1) for the protected procedure handler_name to have the value of the given expression as evaluated +at object creation time. + +757 13 December 2012 + +Pragma Unchecked_Union J.15.6 + + Ada Reference Manual — 2012 Edition + +J.15.8 Shared Variable Pragmas + +The form for pragmas Atomic, Volatile, Independent, Atomic_Components, and +Volatile_Components, and Independent_Components is as follows: + pragma Atomic (local_name); + +Syntax + + pragma Volatile (local_name); + + pragma Independent (component_local_name); + + pragma Atomic_Components (array_local_name); + + pragma Volatile_Components (array_local_name); + + pragma Independent_Components (local_name); + +Name Resolution Rules + +The local_name in an Atomic or Volatile pragma shall resolve to denote either an object_declaration, a +noninherited component_declaration, or a full_type_declaration. The component_local_name in an +to denote a noninherited component_declaration. The +Independent pragma +array_local_name in an Atomic_Components or Volatile_Components pragma shall resolve to denote the +declaration of an array type or an array object of an anonymous type. The local_name in an +Independent_Components pragma shall resolve to denote the declaration of an array or record type or an +array object of an anonymous type. + +resolve + +shall + +1/3 + +2/3 + +3/3 + +4/3 + +5/3 + +6/3 + +7/3 + +8/3 + +9/3 + +These pragmas are representation pragmas (see 13.1). Each of these pragmas specifies that the similarly +named aspect (see C.6) of the type, object, or component denoted by its argument is True. + +Static Semantics + +10/3 + +The local_name of each of these pragmas shall denote a declaration that may have the similarly named +aspect specified. + +Legality Rules + +J.15.9 Pragma CPU + +1/3 + +2/3 + +The form of a pragma CPU is as follows: + pragma CPU (expression); + +Syntax + +3/3 + +The expected type for the expression of a pragma CPU is System.Multiprocessors.CPU_Range. + +Name Resolution Rules + +4/3 + +5/3 + +A CPU pragma is allowed only immediately within a task_definition, or the declarative_part of a +subprogram_body. + +For a CPU pragma that appears in the declarative_part of a subprogram_body, the expression shall be +static. + +Legality Rules + +J.15.8 Shared Variable Pragmas + +13 December 2012 758 + + Ada Reference Manual — 2012 Edition + +Static Semantics + +For an implementation that supports Annex D, a pragma CPU specifies the value of the CPU aspect (see +D.16). If the pragma appears in a task_definition, the expression is associated with the aspect for the task +type or single_task_declaration that contains the pragma; otherwise, the expression is associated with +the aspect for the subprogram that contains the pragma. + +6/3 + +J.15.10 Pragma Dispatching_Domain + +The form of a pragma Dispatching_Domain is as follows: + pragma Dispatching_Domain (expression); + +Syntax + +Name Resolution Rules + +The +the +System.Multiprocessors.Dispatching_Domains.Dispatching_Domain. + +expected + +type + +for + +1/3 + +2/3 + +expression + +is + +3/3 + +A Dispatching_Domain pragma is allowed only immediately within a task_definition. + +Legality Rules + +For an implementation that supports Annex D, a pragma Dispatching_Domain specifies the value of the +Dispatching_Domain aspect (see D.16.1). The expression is associated with the aspect for the task type or +single_task_declaration that contains the pragma. + +Static Semantics + +J.15.11 Pragmas Priority and Interrupt_Priority + +Syntax + +The form of a pragma Priority is as follows: + pragma Priority (expression); + +The form of a pragma Interrupt_Priority is as follows: + pragma Interrupt_Priority [(expression);] + +The expected type for the expression in a Priority or Interrupt_Priority pragma is Integer. + +Name Resolution Rules + +Legality Rules + +A Priority pragma is allowed only immediately within a task_definition, a protected_definition, or the +declarative_part of a subprogram_body. An Interrupt_Priority pragma is allowed only immediately +within a task_definition or a protected_definition. + +For a Priority pragma that appears in the declarative_part of a subprogram_body, the expression shall be +static, and its value shall be in the range of System.Priority. + +4/3 + +5/3 + +1/3 + +2/3 + +3/3 + +4/3 + +5/3 + +6/3 + +7/3 + +For an implementation that supports Annex D, a pragma Priority specifies the value of the Priority aspect +(see D.1) and a pragma Interrupt_Priority specifies the value of the Interrupt_Priority aspect as follows: + +8/3 + +Static Semantics + +759 13 December 2012 + +Pragma CPU J.15.9 + + Ada Reference Manual — 2012 Edition + +9/3 + +• If the pragma appears in a task_definition, the expression is associated with the aspect for the + +task type or single_task_declaration that contains the pragma; + +10/3 + +• If the pragma appears in a protected_definition, the expression is associated with the aspect for + +the protected type or single_protected_declaration that contains the pragma; + +11/3 + +• If the pragma appears in the declarative_part of a subprogram_body, the expression is + +associated with the aspect for the subprogram that contains the pragma. + +12/3 + +If there is no expression in an Interrupt_Priority pragma, the Interrupt_Priority aspect has the value +Interrupt_Priority'Last. + +J.15.12 Pragma Relative_Deadline + +1/3 + +2/3 + +The form of a pragma Relative_Deadline is as follows: + pragma Relative_Deadline (relative_deadline_expression); + +Syntax + +3/3 + +The expected type for a relative_deadline_expression is Real_Time.Time_Span. + +Name Resolution Rules + +4/3 + +A Relative_Deadline pragma is allowed only immediately within a task_definition or the declarative_part +of a subprogram_body. + +Legality Rules + +5/3 + +For an implementation that supports Annex D, a pragma Relative_Deadline specifies the value of the +Relative_Deadline aspect (see D.2.6). If the pragma appears in a task_definition, the expression is +associated with the aspect for the task type or single_task_declaration that contains the pragma; +otherwise, the expression is associated with the aspect for the subprogram that contains the pragma. + +Static Semantics + +J.15.13 Pragma Asynchronous + +1/3 + +2/3 + +3/3 + +Syntax +The form of a pragma Asynchronous, which is a representation pragma (see 13.1), is as follows: + pragma Asynchronous (local_name); + +For an implementation that supports Annex E, a pragma Asynchronous specifies that the Asynchronous +aspect (see E.4.1) for the procedure or type denoted by local_name has the value True. + +Static Semantics + +4/3 + +The local_name of a pragma Asynchronous shall denote a declaration that may have aspect Asynchronous +specified. + +Legality Rules + +J.15.11 Pragmas Priority and Interrupt_Priority + +13 December 2012 760 + + Ada Reference Manual — 2012 Edition + +Annex K +(informative) +Language-Defined Aspects and Attributes + +This annex summarizes the definitions given elsewhere of the language-defined aspects and attributes. +Some aspects have corresponding attributes, as noted. + +1/3 + +K.1 Language-Defined Aspects + +This subclause summarizes the definitions given elsewhere of the language-defined aspects. Aspects are +properties of entities that can be specified by the Ada program; unless otherwise specified below, aspects +can be specified using an aspect_specification. + +Address + +Machine address of an entity. See 13.3. + +Alignment (object) + +Alignment of an object. See 13.3. + +Alignment (subtype) + +Alignment of a subtype. See 13.3. + +All_Calls_Remote + +1/3 + +2/3 + +3/3 + +4/3 + +5/3 + +All remote procedure calls should use the Partition Communication Subsystem, even if they +are local. See E.2.3. + +Asynchronous Remote procedure calls are asynchronous; the caller continues without waiting for the call + +6/3 + +to return. See E.4.1. + +Atomic + +Declare that a type, object, or component is atomic. See C.6. + +Atomic_Components + +Declare that the components of an array type or object are atomic. See C.6. + +Attach_Handler + +Protected procedure is attached to an interrupt. See C.3.1. + +Bit_Order + +Order of bit numbering in a record_representation_clause. See 13.5.3. + +Coding + +Internal +enumeration_representation_clause, not by an aspect_specification. See 13.4. + +representation + +enumeration + +Specified + +literals. + +of + +by + +an + +Component_Size + +Size in bits of a component of an array type. See 13.3. + +Constant_Indexing + +Defines function(s) to implement user-defined indexed_components. See 4.1.6. + +Convention Calling convention or other convention used for interfacing to other languages. See B.1. + +CPU + +Processor on which a given task should run. See D.16. + +Default_Component_Value + +Default value for the components of an array-of-scalar subtype. See 3.6. + +Default_Iterator + +Default iterator to be used in for loops. See 5.5.1. + +Default_Storage_Pool + +Default storage pool for a generic instance. See 13.11.3. + +761 13 December 2012 + +Language-Defined Aspects and Attributes Annex K + +7/3 + +8/3 + +9/3 + +10/3 + +11/3 + +12/3 + +13/3 + +14/3 + +15/3 + +16/3 + +17/3 + +18/3 + + + + + + + + + + + + Ada Reference Manual — 2012 Edition + +19/3 + +Default_Value + +Default value for a scalar subtype. See 3.5. + +20/3 + +Dispatching_Domain + +Domain (group of processors) on which a given task should run. See D.16.1. + +21/3 + +Dynamic_Predicate + +Condition that must hold true for objects of a given subtype; the subtype is not static. See +3.2.4. + +22/3 + +Elaborate_Body + +A given package must have a body, and that body is elaborated immediately after the +declaration. See 10.2.1. + +23/3 + +24/3 + +25/3 + +26/3 + +27/3 + +28/3 + +29/3 + +Export + +Entity is exported to another language. See B.1. + +External_Name + +Name used to identify an imported or exported entity. See B.1. + +External_Tag Unique identifier for a tagged type in streams. See 13.3. + +Implicit_Dereference + +Mechanism for user-defined implicit .all. See 4.1.5. + +Import + +Entity is imported from another language. See B.1. + +Independent Declare that a type, object, or component is independently addressable. See C.6. + +Independent_Components + +Declare that the components of an array or record type, or an array object, are +independently addressable. See C.6. + +30/3 + +31/3 + +Inline + +Input + +For efficiency, Inline calls are requested for a subprogram. See 6.3.2. + +Function to read a value from a stream for a given type, including any bounds and +discriminants. See 13.13.2. + +32/3 + +Interrupt_Handler + +Protected procedure may be attached to interrupts. See C.3.1. + +33/3 + +Interrupt_Priority + +Priority of a task object or type, or priority of a protected object or type; the priority is in +the interrupt range. See D.1. + +34/3 + +Iterator_Element + +Element type to be used for user-defined iterators. See 5.5.1. + +35/3 + +Layout (record) + +Layout of record components. Specified by a record_representation_clause, not by an +aspect_specification. See 13.5.1. + +36/3 + +37/3 + +38/3 + +39/3 + +40/3 + +41/3 + +Link_Name Linker symbol used to identify an imported or exported entity. See B.1. + +Machine_Radix + +Radix (2 or 10) that is used to represent a decimal fixed point type. See F.1. + +No_Return A procedure will not return normally. See 6.5.1. + +Output + +Pack + +Post + +Procedure to write a value to a stream for a given type, including any bounds and +discriminants. See 13.13.2. + +Minimize storage when laying out records and arrays. See 13.2. + +Postcondition; a condition that must hold true after a call. See 6.1.1. + +K.1 Language-Defined Aspects + +13 December 2012 762 + + + + + + + + + + + + + + Ada Reference Manual — 2012 Edition + +Post'Class + +Postcondition inherited on type derivation. See 6.1.1. + +Pre + +Precondition; a condition that must hold true before a call. See 6.1.1. + +Pre'Class + +Precondition inherited on type derivation. See 6.1.1. + +Preelaborate Code execution during elaboration is avoided for a given package. See 10.2.1. + +Priority + +Pure + +Read + +Priority of a task object or type, or priority of a protected object or type; the priority is not +in the interrupt range. See D.1. + +Side effects are avoided in the subprograms of a given package. See 10.2.1. + +Procedure to read a value from a stream for a given type. See 13.13.2. + +Record layout See Layout. See 13.5.1. + +Relative_Deadline + +Task parameter used in Earliest Deadline First Dispatching. See D.2.6. + +Remote_Call_Interface + +Subprograms in a given package may be used in remote procedure calls. See E.2.3. + +Remote_Types + +Types in a given package may be used in remote procedure calls. See E.2.2. + +Shared_Passive + +A given package is used to represent shared memory in a distributed system. See E.2.1. + +Size (object) Size in bits of an object. See 13.3. + +Size (subtype) + +Size in bits of a subtype. See 13.3. + +Small + +Scale factor for a fixed point type. See 3.5.10. + +Static_Predicate + +Condition that must hold true for objects of a given subtype; the subtype may be static. See +3.2.4. + +Storage_Pool Pool of memory from which new will allocate for a given access type. See 13.11. + +Storage_Size (access) + +Sets memory size for allocations for an access type. See 13.11. + +Storage_Size (task) + +Size in storage elements reserved for a task type or single task object. See 13.3. + +Stream_Size Size in bits used to represent elementary objects in a stream. See 13.13.2. + +Synchronization + +Defines whether a given primitive operation of a synchronized interface must be +implemented by an entry or protected procedure. See 9.5. + +Type_Invariant + +A condition that must hold true for all objects of a type. See 7.3.2. + +Type_Invariant'Class + +A condition that must hold true for all objects in a class of types. See 7.3.2. + +Unchecked_Union + +Type is used to interface to a C union type. See B.3.3. + +Variable_Indexing + +Defines function(s) to implement user-defined indexed_components. See 4.1.6. + +Volatile + +Declare that a type, object, or component is volatile. See C.6. + +763 13 December 2012 + +Language-Defined Aspects K.1 + +42/3 + +43/3 + +44/3 + +45/3 + +46/3 + +47/3 + +48/3 + +49/3 + +50/3 + +51/3 + +52/3 + +53/3 + +54/3 + +55/3 + +56/3 + +57/3 + +58/3 + +59/3 + +60/3 + +61/3 + +62/3 + +63/3 + +64/3 + +65/3 + +66/3 + +67/3 + + + + + + + + + + + + + + Ada Reference Manual — 2012 Edition + +68/3 + +Volatile_Components + +Declare that the components of an array type or object are volatile. See C.6. + +69/3 + +Write + +Procedure to write a value to a stream for a given type. See 13.13.2. + +K.2 Language-Defined Attributes + +1/3 + +This subclause summarizes the definitions given elsewhere of the language-defined attributes. Attributes +are properties of entities that can be queried by an Ada program. + +2 + +3 + +4 + +5 + +6/1 + +7 + +8 + +9 + +10 + +11 + +12 + +13 + +P'Access + +For a prefix P that denotes a subprogram: + +P'Access yields an access value that designates the subprogram denoted by P. The type of +P'Access is an access-to-subprogram type (S), as determined by the expected type. See +3.10.2. + +X'Access + +For a prefix X that denotes an aliased view of an object: + +X'Access yields an access value that designates the object denoted by X. The type of +X'Access is an access-to-object type, as determined by the expected type. The expected +type shall be a general access type. See 3.10.2. + +X'Address + +For a prefix X that denotes an object, program unit, or label: + +Denotes the address of the first of the storage elements allocated to X. For a program unit or +label, this value refers to the machine code associated with the corresponding body or +statement. The value of this attribute is of type System.Address. See 13.3. + +S'Adjacent + +For every subtype S of a floating point type T: + +S'Adjacent denotes a function with the following specification: + +function S'Adjacent (X, Towards : T) + return T + +If Towards = X, the function yields X; otherwise, it yields the machine number of the type T +adjacent to X in the direction of Towards, if that machine number exists. If the result would +be outside the base range of S, Constraint_Error is raised. When T'Signed_Zeros is True, a +zero result has the sign of X. When Towards is zero, its sign has no bearing on the result. +See A.5.3. + +S'Aft + +For every fixed point subtype S: + +S'Aft yields the number of decimal digits needed after the decimal point to accommodate +the delta of the subtype S, unless the delta of the subtype S is greater than 0.1, in which +case the attribute yields the value one. (S'Aft is the smallest positive integer N for which +(10**N)*S'Delta is greater than or equal to one.) The value of this attribute is of the type +universal_integer. See 3.5.10. + +13.1/2 + +S'Alignment For every subtype S: + +13.2/2 + +13.3/2 + +The value of this attribute is of type universal_integer, and nonnegative. + +For an object X of subtype S, if S'Alignment is not zero, then X'Alignment is a nonzero +integral multiple of S'Alignment unless specified otherwise by a representation item. See +13.3. + +14/1 + +X'Alignment For a prefix X that denotes an object: + +15 + +The value of this attribute is of type universal_integer, and nonnegative; zero means that +the object is not necessarily aligned on a storage element boundary. If X'Alignment is not + +K.1 Language-Defined Aspects + +13 December 2012 764 + + + + + + + + + + + + Ada Reference Manual — 2012 Edition + +zero, then X is aligned on a storage unit boundary and X'Address is an integral multiple of +X'Alignment (that is, the Address modulo the Alignment is zero). + +See 13.3. + +S'Base + +For every scalar subtype S: + +S'Base denotes an unconstrained subtype of the type of S. This unconstrained subtype is +called the base subtype of the type. See 3.5. + +S'Bit_Order For every specific record subtype S: + +Denotes the bit ordering for the type of S. The value of this attribute is of type +System.Bit_Order. See 13.5.3. + +P'Body_Version + +For a prefix P that statically denotes a program unit: + +Yields a value of the predefined type String that identifies the version of the compilation +unit that contains the body (but not any subunits) of the program unit. See E.3. + +T'Callable + +For a prefix T that is of a task type (after any implicit dereference): + +Yields the value True when the task denoted by T is callable, and False otherwise; See 9.9. + +E'Caller + +For a prefix E that denotes an entry_declaration: + +Yields a value of the type Task_Id that identifies the task whose call is now being serviced. +Use of this attribute is allowed only inside an accept_statement, or entry_body after the +entry_barrier, corresponding to the entry_declaration denoted by E. See C.7.1. + +S'Ceiling + +For every subtype S of a floating point type T: + +S'Ceiling denotes a function with the following specification: + +function S'Ceiling (X : T) + return T + +The function yields the value X, i.e., the smallest (most negative) integral value greater +than or equal to X. When X is zero, the result has the sign of X; a zero result otherwise has a +negative sign when S'Signed_Zeros is True. See A.5.3. + +S'Class + +For every subtype S of a tagged type T (specific or class-wide): + +S'Class denotes a subtype of the class-wide type (called T'Class in this International +Standard) for the class rooted at T (or if S already denotes a class-wide subtype, then +S'Class is the same as S). + +S'Class is unconstrained. However, if S is constrained, then the values of S'Class are only +those that when converted to the type T belong to S. See 3.9. + +S'Class + +For every subtype S of an untagged private type whose full view is tagged: + +Denotes the class-wide subtype corresponding to the full view of S. This attribute is +allowed only from the beginning of the private part in which the full view is declared, until +the declaration of the full view. After the full view, the Class attribute of the full view can +be used. See 7.3.1. + +X'Component_Size + +For a prefix X that denotes an array subtype or array object (after any implicit dereference): + +Denotes the size in bits of components of the type of X. The value of this attribute is of type +universal_integer. See 13.3. + +S'Compose + +For every subtype S of a floating point type T: + +16/2 + +17 + +18 + +19 + +20 + +21/1 + +22 + +23 + +24 + +25 + +26/3 + +27 + +28 + +29 + +30 + +31 + +32 + +33 + +34 + +35 + +36/1 + +37 + +38 + +765 13 December 2012 + +Language-Defined Attributes K.2 + + + + + + + + + + + + + + + + Ada Reference Manual — 2012 Edition + +39 + +40 + +41 + +42 + +A'Constrained + +S'Compose denotes a function with the following specification: + +function S'Compose (Fraction : T; + Exponent : universal_integer) + return T + +Let v be the value Fraction · T'Machine_RadixExponent–k, where k is the normalized exponent +of Fraction. If v is a machine number of the type T, or if |v| ≥ T'Model_Small, the function +yields v; otherwise, it yields either one of the machine numbers of the type T adjacent to v. +Constraint_Error is optionally raised if v is outside the base range of S. A zero result has the +sign of Fraction when S'Signed_Zeros is True. See A.5.3. + +For a prefix A that is of a discriminated type (after any implicit dereference): + +Yields the value True if A denotes a constant, a value, a tagged object, or a constrained +variable, and False otherwise. See 3.7.2. + +S'Copy_Sign For every subtype S of a floating point type T: + +S'Copy_Sign denotes a function with the following specification: + +function S'Copy_Sign (Value, Sign : T) + return T + +If the value of Value is nonzero, the function yields a result whose magnitude is that of +Value and whose sign is that of Sign; otherwise, it yields the value zero. Constraint_Error is +optionally raised if the result is outside the base range of S. A zero result has the sign of +Sign when S'Signed_Zeros is True. See A.5.3. + +E'Count + +For a prefix E that denotes an entry of a task or protected unit: + +Yields the number of calls presently queued on the entry E of the current instance of the +unit. The value of this attribute is of the type universal_integer. See 9.9. + +S'Definite + +For a prefix S that denotes a formal indefinite subtype: + +S'Definite yields True if the actual subtype corresponding to S is definite; otherwise, it +yields False. The value of this attribute is of the predefined type Boolean. See 12.5.1. + +S'Delta + +For every fixed point subtype S: + +S'Delta denotes the delta of the fixed point subtype S. The value of this attribute is of the +type universal_real. See 3.5.10. + +S'Denorm + +For every subtype S of a floating point type T: + +Yields the value True if every value expressible in the form + ± mantissa · T'Machine_RadixT'Machine_Emin +where mantissa is a nonzero T'Machine_Mantissa-digit fraction in the number base +T'Machine_Radix, the first digit of which is zero, is a machine number (see 3.5.7) of the +type T; yields the value False otherwise. The value of this attribute is of the predefined type +Boolean. See A.5.3. + +S'Digits + +For every floating point subtype S: + +S'Digits denotes the requested decimal precision for the subtype S. The value of this +attribute is of the type universal_integer. See 3.5.8. + +S'Digits + +For every decimal fixed point subtype S: + +S'Digits denotes the digits of the decimal fixed point subtype S, which corresponds to the +number of decimal digits that are representable in objects of the subtype. The value of this +attribute is of the type universal_integer. See 3.5.10. + +K.2 Language-Defined Attributes + +13 December 2012 766 + +43/3 + +44 + +45 + +46 + +47 + +48 + +49 + +50/1 + +51/3 + +52 + +53 + +54 + +55 + +56 + +57 + +58 + +59 + + + + + + + + + + + + + + + + Ada Reference Manual — 2012 Edition + +S'Exponent + +For every subtype S of a floating point type T: + +S'Exponent denotes a function with the following specification: + +function S'Exponent (X : T) + return universal_integer + +The function yields the normalized exponent of X. See A.5.3. + +S'External_Tag + +For every subtype S of a tagged type T (specific or class-wide): + +S'External_Tag denotes an external string representation for S'Tag; it is of the predefined +type String. External_Tag may be specified for a specific tagged type via an +attribute_definition_clause; the expression of such a clause shall be static. The default +external tag representation is implementation defined. See 13.13.2. See 13.3. + +60 + +61 + +62 + +63 + +64 + +65 + +A'First + +For a prefix A that is of an array type (after any implicit dereference), or denotes a +constrained array subtype: + +66/1 + +A'First denotes the lower bound of the first index range; its type is the corresponding index +type. See 3.6.2. + +S'First + +For every scalar subtype S: + +S'First denotes the lower bound of the range of S. The value of this attribute is of the type +of S. See 3.5. + +67 + +68 + +69 + +A'First(N) + +For a prefix A that is of an array type (after any implicit dereference), or denotes a +constrained array subtype: + +70/1 + +A'First(N) denotes the lower bound of the N-th index range; its type is the corresponding +index type. See 3.6.2. + +R.C'First_Bit + +For a component C of a composite, non-array object R: + +If the nondefault bit ordering applies to the composite type, and if a component_clause +specifies the placement of C, denotes the value given for the first_bit of the +component_clause; otherwise, denotes the offset, from the start of the first of the storage +elements occupied by C, of the first bit occupied by C. This offset is measured in bits. The +first bit of a storage element is numbered zero. The value of this attribute is of the type +universal_integer. See 13.5.2. + +S'First_Valid + +71 + +72 + +73/2 + +73.1/3 + +For every static discrete subtype S for which there exists at least one value belonging to S +that satisfies any predicate of S: + +S'First_Valid denotes the smallest value that belongs to S and satisfies the predicate of S. +The value of this attribute is of the type of S. See 3.5.5. + +73.2/3 + +S'Floor + +For every subtype S of a floating point type T: + +S'Floor denotes a function with the following specification: + +function S'Floor (X : T) + return T + +The function yields the value X, i.e., the largest (most positive) integral value less than or +equal to X. When X is zero, the result has the sign of X; a zero result otherwise has a +positive sign. See A.5.3. + +S'Fore + +For every fixed point subtype S: + +74 + +75 + +76 + +77 + +78 + +767 13 December 2012 + +Language-Defined Attributes K.2 + + + + + + + + + + + + + + + Ada Reference Manual — 2012 Edition + +79 + +80 + +81 + +82 + +83 + +S'Fore yields the minimum number of characters needed before the decimal point for the +decimal representation of any value of the subtype S, assuming that the representation does +not include an exponent, but includes a one-character prefix that is either a minus sign or a +space. (This minimum number does not include superfluous zeros or underlines, and is at +least 2.) The value of this attribute is of the type universal_integer. See 3.5.10. + +S'Fraction + +For every subtype S of a floating point type T: + +S'Fraction denotes a function with the following specification: + +function S'Fraction (X : T) + return T + +The function yields the value X · T'Machine_Radix–k, where k is the normalized exponent of +X. A zero result, which can only occur when X is zero, has the sign of X. See A.5.3. + +83.1/3 + +X'Has_Same_Storage + +For a prefix X that denotes an object: + +83.2/3 + +83.3/3 + +83.4/3 + +X'Has_Same_Storage denotes a function with the following specification: + +function X'Has_Same_Storage (Arg : any_type) + return Boolean + +The actual parameter shall be a name that denotes an object. The object denoted by the +actual parameter can be of any type. This function evaluates the names of the objects +involved and returns True if the representation of the object denoted by the actual +parameter occupies exactly the same bits as the representation of the object denoted by X; +otherwise, it returns False. See 13.3. + +84/1 + +E'Identity + +For a prefix E that denotes an exception: + +85 + +86 + +87 + +88 + +89 + +90 + +E'Identity returns the unique identity of the exception. The type of this attribute is +Exception_Id. See 11.4.1. + +T'Identity + +For a prefix T that is of a task type (after any implicit dereference): + +Yields a value of the type Task_Id that identifies the task denoted by T. See C.7.1. + +S'Image + +For every scalar subtype S: + +S'Image denotes a function with the following specification: + +function S'Image(Arg : S'Base) + return String + +91/3 + +The function returns an image of the value of Arg as a String. See 3.5. + +92 + +S'Class'Input + +For every subtype S'Class of a class-wide type T'Class: + +S'Class'Input denotes a function with the following specification: + +function S'Class'Input( + Stream : not null access Ada.Streams.Root_Stream_Type'Class) + return T'Class + +First reads the external tag from Stream and determines the corresponding internal tag (by +calling Tags.Descendant_Tag(String'Input(Stream), S'Tag) which might raise Tag_Error — +see 3.9) and then dispatches to the subprogram denoted by the Input attribute of the specific +type identified by the internal tag; returns that result. If the specific type identified by the +internal tag is abstract, Constraint_Error is raised. See 13.13.2. + +S'Input + +For every subtype S of a specific type T: + +S'Input denotes a function with the following specification: + +93 + +94/2 + +95/3 + +96 + +97 + +K.2 Language-Defined Attributes + +13 December 2012 768 + + + + + + + + + + + + + + + + Ada Reference Manual — 2012 Edition + +function S'Input( + Stream : not null access Ada.Streams.Root_Stream_Type'Class) + return T + +98/2 + +S'Input reads and returns one value from Stream, using any bounds or discriminants written +by a corresponding S'Output to determine how much to read. See 13.13.2. + +99 + +A'Last + +For a prefix A that is of an array type (after any implicit dereference), or denotes a +constrained array subtype: + +100/1 + +A'Last denotes the upper bound of the first index range; its type is the corresponding index +type. See 3.6.2. + +S'Last + +For every scalar subtype S: + +S'Last denotes the upper bound of the range of S. The value of this attribute is of the type of +S. See 3.5. + +101 + +102 + +103 + +A'Last(N) + +For a prefix A that is of an array type (after any implicit dereference), or denotes a +constrained array subtype: + +104/1 + +A'Last(N) denotes the upper bound of the N-th index range; its type is the corresponding +index type. See 3.6.2. + +R.C'Last_Bit + +For a component C of a composite, non-array object R: + +If the nondefault bit ordering applies to the composite type, and if a component_clause +specifies the placement of C, denotes the value given for the +last_bit of the +component_clause; otherwise, denotes the offset, from the start of the first of the storage +elements occupied by C, of the last bit occupied by C. This offset is measured in bits. The +value of this attribute is of the type universal_integer. See 13.5.2. + +S'Last_Valid + +105 + +106 + +107/2 + +107.1/3 + +For every static discrete subtype S for which there exists at least one value belonging to S +that satisfies any predicate of S: + +S'Last_Valid denotes the largest value that belongs to S and satisfies the predicate of S. The +value of this attribute is of the type of S. See 3.5.5. + +107.2/3 + +S'Leading_Part + +For every subtype S of a floating point type T: + +S'Leading_Part denotes a function with the following specification: + +function S'Leading_Part (X : T; + Radix_Digits : universal_integer) + return T + +Let v be the value T'Machine_Radixk–Radix_Digits, where k is the normalized exponent of X. The +function yields the value + +• X/v · v, when X is nonnegative and Radix_Digits is positive; +• X/v · v, when X is negative and Radix_Digits is positive. + +Constraint_Error is raised when Radix_Digits is zero or negative. A zero result, which can +only occur when X is zero, has the sign of X. See A.5.3. + +108 + +109 + +110 + +111 + +112 + +113 + +114 + +A'Length + +For a prefix A that is of an array type (after any implicit dereference), or denotes a +constrained array subtype: + +115/1 + +A'Length denotes the number of values of the first index range (zero for a null range); its +type is universal_integer. See 3.6.2. + +116 + +769 13 December 2012 + +Language-Defined Attributes K.2 + + + + + + + + + + + + + + + Ada Reference Manual — 2012 Edition + +117/1 + +A'Length(N) For a prefix A that is of an array type (after any implicit dereference), or denotes a + +constrained array subtype: + +118 + +119 + +120 + +121 + +122 + +A'Length(N) denotes the number of values of the N-th index range (zero for a null range); +its type is universal_integer. See 3.6.2. + +S'Machine + +For every subtype S of a floating point type T: + +S'Machine denotes a function with the following specification: + +function S'Machine (X : T) + return T + +If X is a machine number of the type T, the function yields X; otherwise, it yields the value +obtained by rounding or truncating X to either one of the adjacent machine numbers of the +type T. Constraint_Error is raised if rounding or truncating X to the precision of the +machine numbers results in a value outside the base range of S. A zero result has the sign of +X when S'Signed_Zeros is True. See A.5.3. + +123 + +S'Machine_Emax + +For every subtype S of a floating point type T: + +124 + +Yields the largest (most positive) value of exponent such that every value expressible in the +canonical form (for the type T), having a mantissa of T'Machine_Mantissa digits, is a +machine number (see 3.5.7) of the type T. This attribute yields a value of the type +universal_integer. See A.5.3. + +125 + +S'Machine_Emin + +For every subtype S of a floating point type T: + +126 + +Yields the smallest (most negative) value of exponent such that every value expressible in +the canonical form (for the type T), having a mantissa of T'Machine_Mantissa digits, is a +machine number (see 3.5.7) of the type T. This attribute yields a value of the type +universal_integer. See A.5.3. + +127 + +S'Machine_Mantissa + +For every subtype S of a floating point type T: + +128 + +Yields the largest value of p such that every value expressible in the canonical form (for the +type T), having a p-digit mantissa and an exponent between T'Machine_Emin and +T'Machine_Emax, is a machine number (see 3.5.7) of the type T. This attribute yields a +value of the type universal_integer. See A.5.3. + +129 + +S'Machine_Overflows + +For every subtype S of a floating point type T: + +130 + +Yields the value True if overflow and divide-by-zero are detected and reported by raising +Constraint_Error for every predefined operation that yields a result of the type T; yields the +value False otherwise. The value of this attribute is of the predefined type Boolean. See +A.5.3. + +131 + +S'Machine_Overflows + +For every subtype S of a fixed point type T: + +132 + +Yields the value True if overflow and divide-by-zero are detected and reported by raising +Constraint_Error for every predefined operation that yields a result of the type T; yields the +value False otherwise. The value of this attribute is of the predefined type Boolean. See +A.5.4. + +133 + +S'Machine_Radix + +For every subtype S of a floating point type T: + +K.2 Language-Defined Attributes + +13 December 2012 770 + + + + + + + + + + + + + + + + Ada Reference Manual — 2012 Edition + +Yields the radix of the hardware representation of the type T. The value of this attribute is +of the type universal_integer. See A.5.3. + +S'Machine_Radix + +For every subtype S of a fixed point type T: + +Yields the radix of the hardware representation of the type T. The value of this attribute is +of the type universal_integer. See A.5.4. + +S'Machine_Rounding + +For every subtype S of a floating point type T: + +S'Machine_Rounding denotes a function with the following specification: + +function S'Machine_Rounding (X : T) + return T + +The function yields the integral value nearest to X. If X lies exactly halfway between two +integers, one of those integers is returned, but which of them is returned is unspecified. A +zero result has the sign of X when S'Signed_Zeros is True. This function provides access to +the rounding behavior which is most efficient on the target processor. See A.5.3. + +S'Machine_Rounds + +For every subtype S of a floating point type T: + +Yields the value True if rounding is performed on inexact results of every predefined +operation that yields a result of the type T; yields the value False otherwise. The value of +this attribute is of the predefined type Boolean. See A.5.3. + +S'Machine_Rounds + +For every subtype S of a fixed point type T: + +Yields the value True if rounding is performed on inexact results of every predefined +operation that yields a result of the type T; yields the value False otherwise. The value of +this attribute is of the predefined type Boolean. See A.5.4. + +S'Max + +For every scalar subtype S: + +S'Max denotes a function with the following specification: + +function S'Max(Left, Right : S'Base) + return S'Base + +The function returns the greater of the values of the two parameters. See 3.5. + +S'Max_Alignment_For_Allocation +For every subtype S: + +Denotes the maximum value for Alignment that could be requested by the implementation +via Allocate for an access type whose designated subtype is S. The value of this attribute is +of type universal_integer. See 13.11.1. + +S'Max_Size_In_Storage_Elements +For every subtype S: + +Denotes the maximum value for Size_In_Storage_Elements that could be requested by the +implementation via Allocate for an access type whose designated subtype is S. The value of +this attribute is of type universal_integer. See 13.11.1. + +S'Min + +For every scalar subtype S: + +S'Min denotes a function with the following specification: + +function S'Min(Left, Right : S'Base) + return S'Base + +134 + +135 + +136 + +136.1/2 + +136.2/2 + +136.3/2 + +136.4/2 + +137 + +138 + +139 + +140 + +141 + +142 + +143 + +144 + +144.1/3 + +144.2/3 + +145 + +146/3 + +147 + +148 + +149 + +771 13 December 2012 + +Language-Defined Attributes K.2 + + + + + + + + + + + + + + + + + + + Ada Reference Manual — 2012 Edition + +150 + +The function returns the lesser of the values of the two parameters. See 3.5. + +150.1/2 + +S'Mod + +For every modular subtype S: + +150.2/2 + +150.3/2 + +150.4/2 + +151 + +152 + +153 + +154 + +S'Mod denotes a function with the following specification: +function S'Mod (Arg : universal_integer) + return S'Base + +This function returns Arg mod S'Modulus, as a value of the type of S. See 3.5.4. + +S'Model + +For every subtype S of a floating point type T: + +S'Model denotes a function with the following specification: + +function S'Model (X : T) + return T + +If the Numerics Annex is not supported, the meaning of this attribute is implementation +defined; see G.2.2 for the definition that applies to implementations supporting the +Numerics Annex. See A.5.3. + +155 + +S'Model_Emin + +For every subtype S of a floating point type T: + +156 + +If the Numerics Annex is not supported, this attribute yields an implementation defined +value that is greater than or equal to the value of T'Machine_Emin. See G.2.2 for further +requirements that apply to implementations supporting the Numerics Annex. The value of +this attribute is of the type universal_integer. See A.5.3. + +157 + +S'Model_Epsilon + +For every subtype S of a floating point type T: + +158 + +Yields the value T'Machine_Radix1 – T'Model_Mantissa. The value of this attribute is of the type +universal_real. See A.5.3. + +159 + +S'Model_Mantissa + +For every subtype S of a floating point type T: + +160 + +If the Numerics Annex is not supported, this attribute yields an implementation defined +value that is greater than or equal to d · log(10) / log(T'Machine_Radix) + 1, where d is +the requested decimal precision of T, and less than or equal to the value of +T'Machine_Mantissa. See G.2.2 for further requirements that apply to implementations +supporting the Numerics Annex. The value of this attribute is of the type universal_integer. +See A.5.3. + +161 + +S'Model_Small + +For every subtype S of a floating point type T: + +162 + +163 + +164 + +Yields the value T'Machine_RadixT'Model_Emin – 1. The value of this attribute is of the type +universal_real. See A.5.3. + +S'Modulus + +For every modular subtype S: + +S'Modulus yields the modulus of the type of S, as a value of the type universal_integer. See +3.5.4. + +164.1/3 + +X'Old + +For a prefix X that denotes an object of a nonlimited type: + +164.2/3 + +For each X'Old in a postcondition expression that is enabled, a constant is implicitly +declared at the beginning of the subprogram or entry. The constant is of the type of X and is +initialized to the result of evaluating X (as an expression) at the point of the constant +declaration. The value of X'Old in the postcondition expression is the value of this constant; +the type of X'Old is the type of X. These implicit constant declarations occur in an arbitrary +order. See 6.1.1. + +K.2 Language-Defined Attributes + +13 December 2012 772 + + + + + + + + + + + + + + + + + Ada Reference Manual — 2012 Edition + +S'Class'Output + +For every subtype S'Class of a class-wide type T'Class: + +S'Class'Output denotes a procedure with the following specification: + +procedure S'Class'Output( + Stream : not null access Ada.Streams.Root_Stream_Type'Class; + Item : in T'Class) + +First writes the external tag of Item to Stream (by calling String'Output(Stream, Tags.- +External_Tag(Item'Tag)) — see 3.9) and then dispatches to the subprogram denoted by the +Output attribute of the specific type identified by the tag. Tag_Error is raised if the tag of +Item identifies a type declared at an accessibility level deeper than that of S. See 13.13.2. + +S'Output + +For every subtype S of a specific type T: + +S'Output denotes a procedure with the following specification: + +procedure S'Output( + Stream : not null access Ada.Streams.Root_Stream_Type'Class; + Item : in T) + +165 + +166 + +167/2 + +168/2 + +169 + +170 + +171/2 + +S'Output writes the value of Item to Stream, including any bounds or discriminants. See +13.13.2. + +172 + +X'Overlaps_Storage + +For a prefix X that denotes an object: + +X'Overlaps_Storage denotes a function with the following specification: + +function X'Overlaps_Storage (Arg : any_type) + return Boolean + +The actual parameter shall be a name that denotes an object. The object denoted by the +actual parameter can be of any type. This function evaluates the names of the objects +involved and returns True if the representation of the object denoted by the actual +parameter shares at least one bit with the representation of the object denoted by X; +otherwise, it returns False. See 13.3. + +For a prefix D that denotes a library-level declaration, excepting a declaration of or within a +declared-pure library unit: + +Denotes a value of the type universal_integer that identifies the partition in which D was +elaborated. If D denotes the declaration of a remote call interface library unit (see E.2.3) the +given partition is the one where the body of D was elaborated. See E.1. + +D'Partition_Id + +S'Pos + +For every discrete subtype S: + +S'Pos denotes a function with the following specification: + +function S'Pos(Arg : S'Base) + return universal_integer + +This function returns the position number of the value of Arg, as a value of type +universal_integer. See 3.5.5. + +R.C'Position For a component C of a composite, non-array object R: + +If the nondefault bit ordering applies to the composite type, and if a component_clause +specifies the placement of C, denotes the value given for the position of the +component_clause; otherwise, denotes the same value as R.C'Address – R'Address. The +value of this attribute is of the type universal_integer. See 13.5.2. + +S'Pred + +For every scalar subtype S: + +S'Pred denotes a function with the following specification: + +172.1/3 + +172.2/3 + +172.3/3 + +172.4/3 + +173/1 + +174 + +175 + +176 + +177 + +178 + +179 + +180/2 + +181 + +182 + +773 13 December 2012 + +Language-Defined Attributes K.2 + + + + + + + + + + + + + + + + Ada Reference Manual — 2012 Edition + +183 + +184 + +function S'Pred(Arg : S'Base) + return S'Base + +For an enumeration type, the function returns the value whose position number is one less +than that of the value of Arg; Constraint_Error is raised if there is no such value of the type. +For an integer type, the function returns the result of subtracting one from the value of Arg. +For a fixed point type, the function returns the result of subtracting small from the value of +Arg. For a floating point type, the function returns the machine number (as defined in 3.5.7) +immediately below the value of Arg; Constraint_Error is raised if there is no such machine +number. See 3.5. + +184.1/2 + +P'Priority + +For a prefix P that denotes a protected object: + +184.2/2 + +Denotes a non-aliased component of the protected object P. This component is of type +System.Any_Priority and its value is the priority of P. P'Priority denotes a variable if and +only if P denotes a variable. A reference to this attribute shall appear only within the body +of P. See D.5.2. + +185/1 + +A'Range + +For a prefix A that is of an array type (after any implicit dereference), or denotes a +constrained array subtype: + +186 + +187 + +188 + +A'Range is equivalent to the range A'First .. A'Last, except that the prefix A is only +evaluated once. See 3.6.2. + +S'Range + +For every scalar subtype S: + +S'Range is equivalent to the range S'First .. S'Last. See 3.5. + +189/1 + +A'Range(N) For a prefix A that is of an array type (after any implicit dereference), or denotes a + +constrained array subtype: + +190 + +191 + +192 + +193/2 + +194 + +195 + +196 + +197/2 + +198 + +199 + +200 + +201 + +202 + +A'Range(N) is equivalent to the range A'First(N) .. A'Last(N), except that the prefix A is +only evaluated once. See 3.6.2. + +S'Class'Read For every subtype S'Class of a class-wide type T'Class: + +S'Class'Read denotes a procedure with the following specification: + +procedure S'Class'Read( + Stream : not null access Ada.Streams.Root_Stream_Type'Class; + Item : out T'Class) + +Dispatches to the subprogram denoted by the Read attribute of the specific type identified +by the tag of Item. See 13.13.2. + +S'Read + +For every subtype S of a specific type T: + +S'Read denotes a procedure with the following specification: + +procedure S'Read( + Stream : not null access Ada.Streams.Root_Stream_Type'Class; + Item : out T) + +S'Read reads the value of Item from Stream. See 13.13.2. + +S'Remainder For every subtype S of a floating point type T: + +S'Remainder denotes a function with the following specification: + +function S'Remainder (X, Y : T) + return T + +For nonzero Y, let v be the value X – n · Y, where n is the integer nearest to the exact value +of X/Y; if |n – X/Y| = 1/2, then n is chosen to be even. If v is a machine number of the type +T, the function yields v; otherwise, it yields zero. Constraint_Error is raised if Y is zero. A +zero result has the sign of X when S'Signed_Zeros is True. See A.5.3. + +K.2 Language-Defined Attributes + +13 December 2012 774 + + + + + + + + + + + + + Ada Reference Manual — 2012 Edition + +F'Result + +For a prefix F that denotes a function declaration: + +Within a postcondition expression for function F, denotes the result object of the function. +The type of this attribute is that of the function result except within a Post'Class +postcondition expression for a function with a controlling result or with a controlling access +result. For a controlling result, the type of the attribute is T'Class, where T is the function +result type. For a controlling access result, the type of the attribute is an anonymous access +type whose designated type is T'Class, where T is the designated type of the function result +type. See 6.1.1. + +S'Round + +For every decimal fixed point subtype S: + +S'Round denotes a function with the following specification: + +function S'Round(X : universal_real) + return S'Base + +The function returns the value obtained by rounding X (away from 0, if X is midway +between two values of the type of S). See 3.5.10. + +S'Rounding For every subtype S of a floating point type T: + +S'Rounding denotes a function with the following specification: + +function S'Rounding (X : T) + return T + +The function yields the integral value nearest to X, rounding away from zero if X lies +exactly halfway between two integers. A zero result has the sign of X when S'Signed_Zeros +is True. See A.5.3. + +S'Safe_First + +For every subtype S of a floating point type T: + +Yields the lower bound of the safe range (see 3.5.7) of the type T. If the Numerics Annex is +not supported, the value of this attribute is implementation defined; see G.2.2 for the +definition that applies to implementations supporting the Numerics Annex. The value of +this attribute is of the type universal_real. See A.5.3. + +S'Safe_Last For every subtype S of a floating point type T: + +Yields the upper bound of the safe range (see 3.5.7) of the type T. If the Numerics Annex is +not supported, the value of this attribute is implementation defined; see G.2.2 for the +definition that applies to implementations supporting the Numerics Annex. The value of +this attribute is of the type universal_real. See A.5.3. + +S'Scale + +For every decimal fixed point subtype S: + +S'Scale denotes the scale of the subtype S, defined as the value N such that S'Delta = +10.0**(–N). The scale indicates the position of the point relative to the rightmost significant +digits of values of subtype S. The value of this attribute is of the type universal_integer. +See 3.5.10. + +S'Scaling + +For every subtype S of a floating point type T: + +S'Scaling denotes a function with the following specification: + +function S'Scaling (X : T; + Adjustment : universal_integer) + return T + +Let v be the value X · T'Machine_RadixAdjustment. If v is a machine number of the type T, or if +|v| ≥ T'Model_Small, the function yields v; otherwise, it yields either one of the machine +numbers of the type T adjacent to v. Constraint_Error is optionally raised if v is outside the +base range of S. A zero result has the sign of X when S'Signed_Zeros is True. See A.5.3. + +202.1/3 + +202.2/3 + +203 + +204 + +205 + +206 + +207 + +208 + +209 + +210 + +211 + +212 + +213 + +214 + +215 + +216 + +217 + +218 + +219 + +220 + +775 13 December 2012 + +Language-Defined Attributes K.2 + + + + + + + + + + + + + Ada Reference Manual — 2012 Edition + +221 + +S'Signed_Zeros + +For every subtype S of a floating point type T: + +222 + +223 + +224 + +225 + +226 + +227 + +Yields the value True if the hardware representation for the type T has the capability of +representing both positively and negatively signed zeros, these being generated and used by +the predefined operations of the type T as specified in IEC 559:1989; yields the value False +otherwise. The value of this attribute is of the predefined type Boolean. See A.5.3. + +S'Size + +For every subtype S: + +If S is definite, denotes the size (in bits) that the implementation would choose for the +following objects of subtype S: + +• A record component of subtype S when the record type is packed. +• The formal parameter of an instance of Unchecked_Conversion that converts + +from subtype S to some other subtype. + +If S is indefinite, the meaning is implementation defined. The value of this attribute is of +the type universal_integer. See 13.3. + +228/1 + +X'Size + +For a prefix X that denotes an object: + +229 + +230 + +231 + +Denotes the size in bits of the representation of the object. The value of this attribute is of +the type universal_integer. See 13.3. + +S'Small + +For every fixed point subtype S: + +S'Small denotes the small of the type of S. The value of this attribute is of the type +universal_real. See 3.5.10. + +232 + +S'Storage_Pool + +For every access-to-object subtype S: + +233 + +Denotes the storage pool of the type of S. The type of this attribute is Root_Storage_- +Pool'Class. See 13.11. + +234 + +S'Storage_Size + +For every access-to-object subtype S: + +235 + +Yields the result of calling Storage_Size(S'Storage_Pool), which is intended to be a +measure of the number of storage elements reserved for the pool. The type of this attribute +is universal_integer. See 13.11. + +236/1 + +T'Storage_Size + +237 + +For a prefix T that denotes a task object (after any implicit dereference): + +Denotes the number of storage elements reserved for the task. The value of this attribute is +of the type universal_integer. The Storage_Size includes the size of the task's stack, if any. +The language does not specify whether or not it includes other storage associated with the +task (such as the “task control block” used by some implementations.) See 13.3. + +237.1/3 + +S'Stream_Size + +For every subtype S of an elementary type T: + +237.2/3 + +237.3/2 + +237.4/2 + +Denotes the number of bits read from or written to a stream by the default implementations +of S'Read and S'Write. Hence, the number of stream elements required per item of +elementary type T is: + +T'Stream_Size / Ada.Streams.Stream_Element'Size + +The value of +Stream_Element'Size. See 13.13.2. + +this attribute + +is of + +type universal_integer and + +is a multiple of + +238 + +S'Succ + +For every scalar subtype S: + +K.2 Language-Defined Attributes + +13 December 2012 776 + + + + + + + + + + + + + + + + + Ada Reference Manual — 2012 Edition + +S'Succ denotes a function with the following specification: + +function S'Succ(Arg : S'Base) + return S'Base + +For an enumeration type, the function returns the value whose position number is one more +than that of the value of Arg; Constraint_Error is raised if there is no such value of the type. +For an integer type, the function returns the result of adding one to the value of Arg. For a +fixed point type, the function returns the result of adding small to the value of Arg. For a +floating point type, the function returns the machine number (as defined in 3.5.7) +immediately above the value of Arg; Constraint_Error is raised if there is no such machine +number. See 3.5. + +S'Tag + +For every subtype S of a tagged type T (specific or class-wide): + +S'Tag denotes the tag of the type T (or if T is class-wide, the tag of the root type of the +corresponding class). The value of this attribute is of type Tag. See 3.9. + +X'Tag + +For a prefix X that is of a class-wide tagged type (after any implicit dereference): + +X'Tag denotes the tag of X. The value of this attribute is of type Tag. See 3.9. + +T'Terminated For a prefix T that is of a task type (after any implicit dereference): + +Yields the value True if the task denoted by T is terminated, and False otherwise. The value +of this attribute is of the predefined type Boolean. See 9.9. + +S'Truncation For every subtype S of a floating point type T: + +S'Truncation denotes a function with the following specification: + +function S'Truncation (X : T) + return T + +The function yields the value X when X is negative, and X otherwise. A zero result has +the sign of X when S'Signed_Zeros is True. See A.5.3. + +S'Unbiased_Rounding + +For every subtype S of a floating point type T: + +S'Unbiased_Rounding denotes a function with the following specification: + +function S'Unbiased_Rounding (X : T) + return T + +The function yields the integral value nearest to X, rounding toward the even integer if X +lies exactly halfway between two integers. A zero result has the sign of X when +S'Signed_Zeros is True. See A.5.3. + +X'Unchecked_Access + +For a prefix X that denotes an aliased view of an object: + +rules and semantics + +All +to +X'Unchecked_Access, except that, for the purposes of accessibility rules and checks, it is as +if X were declared immediately within a library package. See 13.10. + +(see 3.10.2) apply also + +to X'Access + +that apply + +S'Val + +For every discrete subtype S: + +S'Val denotes a function with the following specification: + +function S'Val(Arg : universal_integer) + return S'Base + +This function returns a value of the type of S whose position number equals the value of +Arg. See 3.5.5. + +X'Valid + +For a prefix X that denotes a scalar object (after any implicit dereference): + +777 13 December 2012 + +Language-Defined Attributes K.2 + +239 + +240 + +241 + +242 + +243 + +244 + +245 + +246 + +247 + +248 + +249 + +250 + +251 + +252 + +253 + +254 + +255 + +256 + +257 + +258 + +259 + +260 + +261 + +262 + + + + + + + + + + + + + + + + Ada Reference Manual — 2012 Edition + +263/3 + +264 + +265 + +266 + +267 + +Yields True if and only if the object denoted by X is normal, has a valid representation, and +the predicate of the nominal subtype of X evaluates to True. The value of this attribute is of +the predefined type Boolean. See 13.9.2. + +S'Value + +For every scalar subtype S: + +S'Value denotes a function with the following specification: + +function S'Value(Arg : String) + return S'Base + +This function returns a value given an image of the value as a String, ignoring any leading +or trailing spaces. See 3.5. + +268/1 + +P'Version + +For a prefix P that statically denotes a program unit: + +269 + +270 + +271 + +272 + +273/3 + +Yields a value of the predefined type String that identifies the version of the compilation +unit that contains the declaration of the program unit. See E.3. + +S'Wide_Image For every scalar subtype S: + +S'Wide_Image denotes a function with the following specification: + +function S'Wide_Image(Arg : S'Base) + return Wide_String + +The function returns an image of the value of Arg as a Wide_String. See 3.5. + +274 + +S'Wide_Value + +For every scalar subtype S: + +275 + +276 + +277 + +S'Wide_Value denotes a function with the following specification: + +function S'Wide_Value(Arg : Wide_String) + return S'Base + +This function returns a value given an image of the value as a Wide_String, ignoring any +leading or trailing spaces. See 3.5. + +277.1/2 + +S'Wide_Wide_Image + +For every scalar subtype S: + +277.2/2 + +277.3/2 + +277.4/2 + +S'Wide_Wide_Image denotes a function with the following specification: + +function S'Wide_Wide_Image(Arg : S'Base) + return Wide_Wide_String + +The function returns an image of the value of Arg, that is, a sequence of characters +representing the value in display form. See 3.5. + +277.5/2 + +S'Wide_Wide_Value + +For every scalar subtype S: + +277.6/2 + +277.7/2 + +277.8/2 + +S'Wide_Wide_Value denotes a function with the following specification: + +function S'Wide_Wide_Value(Arg : Wide_Wide_String) + return S'Base + +This function returns a value given an image of the value as a Wide_Wide_String, ignoring +any leading or trailing spaces. See 3.5. + +277.9/2 + +S'Wide_Wide_Width + +For every scalar subtype S: + +277.10/2 + +S'Wide_Wide_Width denotes the maximum length of a Wide_Wide_String returned by +S'Wide_Wide_Image over all values of the subtype S. It denotes zero for a subtype that has +a null range. Its type is universal_integer. See 3.5. + +K.2 Language-Defined Attributes + +13 December 2012 778 + + + + + + + + + + + + + + + + + + + Ada Reference Manual — 2012 Edition + +S'Wide_Width + +For every scalar subtype S: + +S'Wide_Width denotes the maximum length of a Wide_String returned by S'Wide_Image +over all values of the subtype S. It denotes zero for a subtype that has a null range. Its type +is universal_integer. See 3.5. + +S'Width + +For every scalar subtype S: + +S'Width denotes the maximum length of a String returned by S'Image over all values of the +subtype S. It denotes zero for a subtype that has a null range. Its type is universal_integer. +See 3.5. + +S'Class'Write + +For every subtype S'Class of a class-wide type T'Class: + +S'Class'Write denotes a procedure with the following specification: + +procedure S'Class'Write( + Stream : not null access Ada.Streams.Root_Stream_Type'Class; + Item : in T'Class) + +278 + +279 + +280 + +281 + +282 + +283 + +284/2 + +Dispatches to the subprogram denoted by the Write attribute of the specific type identified +by the tag of Item. See 13.13.2. + +285 + +S'Write + +For every subtype S of a specific type T: + +S'Write denotes a procedure with the following specification: + +procedure S'Write( + Stream : not null access Ada.Streams.Root_Stream_Type'Class; + Item : in T) + +S'Write writes the value of Item to Stream. See 13.13.2. + +286 + +287 + +288/2 + +289 + +779 13 December 2012 + +Language-Defined Attributes K.2 + + + + + + + + + + Ada Reference Manual — 2012 Edition + +Annex L +(informative) +Language-Defined Pragmas + +This Annex summarizes the definitions given elsewhere of the language-defined pragmas. + +pragma All_Calls_Remote[(library_unit_name)]; — See E.2.3. + +pragma Assert([Check =>] boolean_expression[, [Message =>] string_expression]); — See 11.4.2. + +pragma Assertion_Policy(policy_identifier); — See 11.4.2. + +pragma Assertion_Policy( + assertion_aspect_mark => policy_identifier + {, assertion_aspect_mark => policy_identifier}); — See 11.4.2. + +This paragraph was deleted. + +pragma Asynchronous (local_name); — See J.15.13. + +This paragraph was deleted. + +pragma Atomic (local_name); — See J.15.8. + +This paragraph was deleted. + +pragma Atomic_Components (array_local_name); — See J.15.8. + +This paragraph was deleted. + +pragma Attach_Handler (handler_name, expression); — See J.15.7. + +This paragraph was deleted. + +This paragraph was deleted. + +pragma Convention([Convention =>] convention_identifier,[Entity =>] local_name); — See J.15.5. + +pragma CPU (expression); — See J.15.9. + +pragma Default_Storage_Pool (storage_pool_indicator); — See 13.11.3. + +pragma Detect_Blocking; — See H.5. + +pragma Discard_Names[([On => ] local_name)]; — See C.5. + +pragma Dispatching_Domain (expression); — See J.15.10. + +pragma Elaborate(library_unit_name{, library_unit_name}); — See 10.2.1. + +pragma Elaborate_All(library_unit_name{, library_unit_name}); — See 10.2.1. + +pragma Elaborate_Body[(library_unit_name)]; — See 10.2.1. + +This paragraph was deleted. + +pragma Export( + [Convention =>] convention_identifier, [Entity =>] local_name + [, [External_Name =>] external_name_string_expression] + +781 13 December 2012 + +Language-Defined Pragmas Annex L + +1 + +2 + +2.1/2 + +2.2/2 + +2.3/3 + +3/3 + +3.1/3 + +4/3 + +4.1/3 + +5/3 + +5.1/3 + +6/3 + +6.1/3 + +7/3 + +8/3 + +8.1/3 + +8.2/3 + +8.3/3 + +8.4/2 + +9 + +9.1/3 + +10 + +11 + +12 + +13/3 + +13.1/3 + + Ada Reference Manual — 2012 Edition + + [, [Link_Name =>] link_name_string_expression]); — See J.15.5. + +14/3 + +This paragraph was deleted. + +14.1/3 + +pragma Import( + [Convention =>] convention_identifier, [Entity =>] local_name + [, [External_Name =>] external_name_string_expression] + [, [Link_Name =>] link_name_string_expression]); — See J.15.5. + +14.2/3 + +pragma Independent (component_local_name); — See J.15.8. + +14.3/3 + +pragma Independent_Components (local_name); — See J.15.8. + +15/3 + +This paragraph was deleted. + +15.1/3 + +pragma Inline (name{, name}); — See J.15.1. + +16 + +pragma Inspection_Point[(object_name {, object_name})]; — See H.3.2. + +17/3 + +This paragraph was deleted. + +17.1/3 + +pragma Interrupt_Handler (handler_name); — See J.15.7. + +18/3 + +This paragraph was deleted. + +18.1/3 + +pragma Interrupt_Priority [(expression);] — See J.15.11. + +19 + +20 + +21 + +pragma Linker_Options(string_expression); — See B.1. + +pragma List(identifier); — See 2.8. + +pragma Locking_Policy(policy_identifier); — See D.3. + +21.1/3 + +This paragraph was deleted. + +21.2/3 + +pragma No_Return (procedure_local_name{, procedure_local_name}); — See J.15.2. + +22 + +23 + +pragma Normalize_Scalars; — See H.1. + +pragma Optimize(identifier); — See 2.8. + +24/3 + +This paragraph was deleted. + +24.1/3 + +pragma Pack (first_subtype_local_name); — See J.15.3. + +25 + +pragma Page; — See 2.8. + +25.1/2 + +pragma Partition_Elaboration_Policy (policy_identifier); — See H.6. + +25.2/2 + +pragma Preelaborable_Initialization(direct_name); — See 10.2.1. + +26 + +pragma Preelaborate[(library_unit_name)]; — See 10.2.1. + +27/3 + +This paragraph was deleted. + +27.1/3 + +pragma Priority (expression); — See J.15.11. + +27.2/2 + +pragma Priority_Specific_Dispatching ( + policy_identifier, first_priority_expression, last_priority_expression); — See D.2.2. + +27.3/3 + +pragma Profile (profile_identifier {, profile_pragma_argument_association}); — See 13.12. + +Annex L Language-Defined Pragmas + +13 December 2012 782 + + Ada Reference Manual — 2012 Edition + +This paragraph was deleted. + +pragma Pure[(library_unit_name)]; — See 10.2.1. + +pragma Queuing_Policy(policy_identifier); — See D.4. + +This paragraph was deleted. + +pragma Relative_Deadline (relative_deadline_expression); — See J.15.12. + +pragma Remote_Call_Interface[(library_unit_name)]; — See E.2.3. + +pragma Remote_Types[(library_unit_name)]; — See E.2.2. + +pragma Restrictions(restriction{, restriction}); — See 13.12. + +pragma Reviewable; — See H.3.1. + +pragma Shared_Passive[(library_unit_name)]; — See E.2.1. + +This paragraph was deleted. + +pragma Storage_Size (expression); — See J.15.4. + +pragma Suppress(identifier); — See 11.5. + +pragma Task_Dispatching_Policy(policy_identifier); — See D.2.2. + +This paragraph was deleted. + +pragma Unchecked_Union (first_subtype_local_name); — See J.15.6. + +pragma Unsuppress(identifier); — See 11.5. + +This paragraph was deleted. + +pragma Volatile (local_name); — See J.15.8. + +This paragraph was deleted. + +pragma Volatile_Components (array_local_name); — See J.15.8. + +27.4/3 + +28 + +29 + +29.1/3 + +29.2/3 + +30 + +31 + +32 + +33 + +34 + +35/3 + +35.1/3 + +36 + +37 + +37.1/3 + +37.2/3 + +37.3/2 + +38/3 + +38.1/3 + +39/3 + +39.1/3 + +783 13 December 2012 + +Language-Defined Pragmas Annex L + + Ada Reference Manual — 2012 Edition + +Annex M +(informative) +Summary of Documentation Requirements + +The Ada language allows for certain target machine dependences in a controlled manner. Each Ada +implementation must document many characteristics and properties of the target system. This International +Standard contains specific documentation requirements. In addition, many characteristics that require +documentation are identified throughout this International Standard as being implementation defined. +Finally, this International Standard requires documentation of whether implementation advice is followed. +The following subclauses provide summaries of these documentation requirements. + +1/3 + +M.1 Specific Documentation Requirements + +In addition to implementation-defined characteristics, each Ada implementation must document various +properties of the implementation: + +• The behavior of implementations in implementation-defined situations shall be documented — + +see M.2, “Implementation-Defined Characteristics” for a listing. See 1.1.3(19). + +• The set of values that a user-defined Allocate procedure needs to accept for the Alignment +parameter. How the standard storage pool is chosen, and how storage is allocated by standard +storage pools. See 13.11(22). + +• The algorithm used for random number generation, including a description of its period. See + +A.5.2(44). + +• The minimum time interval between calls to the time-dependent Reset procedure that is + +guaranteed to initiate different random number sequences. See A.5.2(45). + +• The conditions under which Io_Exceptions.Name_Error, Io_Exceptions.Use_Error, and + +Io_Exceptions.Device_Error are propagated. See A.13(15). + +• The behavior of package Environment_Variables when environment variables are changed by + +external mechanisms. See A.17(30/2). + +• The overhead of calling machine-code or intrinsic subprograms. See C.1(6). +• The types and attributes used in machine code insertions. See C.1(7). +• The subprogram calling conventions for all supported convention identifiers. See C.1(8/3). +• The mapping between the Link_Name or Ada designator and the external link name. See C.1(9). +• The treatment of interrupts. See C.3(22). +• The metrics for interrupt handlers. See C.3.1(16). +• If the Ceiling_Locking policy is in effect, the default ceiling priority for a protected object that + +specifies an interrupt handler aspect. See C.3.2(24/3). + +• Any circumstances when the elaboration of a preelaborated package causes code to be executed. + +See C.4(12). + +• Whether a partition can be restarted without reloading. See C.4(13). +• The effect of calling Current_Task from an entry body or interrupt handler. See C.7.1(19). + +1/2 + +2/2 + +3/2 + +4/2 + +5/2 + +6/2 + +7/2 + +8/2 + +9/2 + +10/2 + +11/2 + +12/2 + +13/2 + +14/3 + +15/2 + +16/2 + +17/2 + +785 13 December 2012 + +Summary of Documentation Requirements Annex M + + Ada Reference Manual — 2012 Edition + +18/2 + +• For package Task_Attributes, limits on the number and size of task attributes, and how to + +configure any limits. See C.7.2(19). + +19/2 + +20/2 + +21/2 + +• The metrics for the Task_Attributes package. See C.7.2(27). +• The details of the configuration used to generate the values of all metrics. See D(2). +• The maximum priority inversion a user task can experience from the implementation. See + +D.2.3(12/2). + +22/2 + +• The amount of time that a task can be preempted for processing on behalf of lower-priority + +tasks. See D.2.3(13/2). + +23/2 + +24/2 + +• The quantum values supported for round robin dispatching. See D.2.5(16/2). +• The accuracy of the detection of the exhaustion of the budget of a task for round robin + +dispatching. See D.2.5(17/2). + +25/2 + +• Any conditions that cause the completion of the setting of the deadline of a task to be delayed + +for a multiprocessor. See D.2.6(32/2). + +26/2 + +• Any conditions that cause the completion of the setting of the priority of a task to be delayed for + +a multiprocessor. See D.5.1(12.1/2). + +27/2 + +28/2 + +29/2 + +30/2 + +31/2 + +32/2 + +33/2 + +34/2 + +35/2 + +36/2 + +• The metrics for Set_Priority. See D.5.1(14). +• The metrics for setting the priority of a protected object. See D.5.2(10). +• On a multiprocessor, any conditions that cause the completion of an aborted construct to be + +delayed later than what is specified for a single processor. See D.6(3). + +• The metrics for aborts. See D.6(8). +• The values of Time_First, Time_Last, Time_Span_First, Time_Span_Last, Time_Span_Unit, + +and Tick for package Real_Time. See D.8(33). + +• The properties of the underlying time base used in package Real_Time. See D.8(34). +• Any synchronization of package Real_Time with external time references. See D.8(35). +• Any aspects of the external environment that could interfere with package Real_Time. See + +D.8(36/3). + +• The metrics for package Real_Time. See D.8(45). +• The minimum value of the delay expression of a delay_relative_statement that causes a task to + +actually be blocked. See D.9(7). + +37/2 + +• The minimum difference between the value of the delay expression of a delay_until_statement + +and the value of Real_Time.Clock, that causes the task to actually be blocked. See D.9(8). + +38/2 + +39/2 + +40/2 + +41/2 + +• The metrics for delay statements. See D.9(13). +• The upper bound on the duration of interrupt blocking caused by the implementation. See + +D.12(5). + +• The metrics for entry-less protected objects. See D.12(12). +• The values of CPU_Time_First, CPU_Time_Last, CPU_Time_Unit, and CPU_Tick of package + +Execution_Time. See D.14(21/2). + +42/3 + +• The properties of the mechanism used to implement package Execution_Time, including the + +values of the constants defined in the package. See D.14(22/2). + +43/2 + +• The metrics for execution time. See D.14(27). + +M.1 Specific Documentation Requirements + +13 December 2012 786 + + Ada Reference Manual — 2012 Edition + +• The metrics for timing events. See D.15(24). +• The processor(s) on which the clock interrupt is handled; the processors on which each + +44/2 + +44.1/3 + +Interrupt_Id can be handled. See D.16.1(32). + +• Whether the RPC-receiver is invoked from concurrent tasks, and if so, the number of such tasks. + +See E.5(25). + +• Any techniques used to reduce cancellation errors in Numerics.Generic_Real_Arrays shall be + +documented. See G.3.1(86/2). + +• Any techniques used to reduce cancellation errors in Numerics.Generic_Complex_Arrays shall + +be documented. See G.3.2(155/2). + +• If a pragma Normalize_Scalars applies, the implicit initial values of scalar subtypes shall be +documented. Such a value should be an invalid representation when possible; any cases when is +it not shall be documented. See H.1(5/2). + +• The range of effects for each bounded error and each unspecified effect. If the effects of a given + +erroneous construct are constrained, the constraints shall be documented. See H.2(1). + +• For each inspection point, a mapping between each inspectable object and the machine resources + +where the object's value can be obtained shall be provided. See H.3.2(8). + +• If a pragma Restrictions(No_Exceptions) is specified, the effects of all constructs where + +language-defined checks are still performed. See H.4(25). + +• The interrupts to which a task entry may be attached. See J.7.1(12). +• The type of entry call invoked for an interrupt entry. See J.7.1(13). + +M.2 Implementation-Defined Characteristics + +The Ada language allows for certain machine dependences in a controlled manner. Each Ada +implementation must document all implementation-defined characteristics: + +• Whether or not each recommendation given in Implementation Advice is followed — see M.3, + +“Implementation Advice” for a listing. See 1.1.2(37). +• Capacity limitations of the implementation. See 1.1.3(3). +• Variations from the standard that are impractical to avoid given the implementation's execution + +environment. See 1.1.3(6). + +• Which code_statements cause external interactions. See 1.1.3(10). +• The coded representation for the text of an Ada program. See 2.1(4/3). +• The semantics of an Ada program whose text is not in Normalization Form KC. See 2.1(4.1/3). +• This paragraph was deleted. +• The representation for an end of line. See 2.2(2/3). +• Maximum supported line length and lexical element length. See 2.2(14). +• Implementation-defined pragmas. See 2.8(14). +• Effect of pragma Optimize. See 2.8(27). +• The sequence of characters of the value returned by S'Wide_Image when some of the graphic + +characters of S'Wide_Wide_Image are not defined in Wide_Character. See 3.5(30/3). + +45/2 + +46/2 + +47/2 + +48/2 + +49/2 + +50/2 + +51/2 + +52/2 + +53/2 + +1/2 + +2/2 + +3 + +4 + +5 + +6 + +6.1/2 + +7/2 + +8 + +9 + +10 + +11 + +11.1/2 + +787 13 December 2012 + +Specific Documentation Requirements M.1 + + Ada Reference Manual — 2012 Edition + +12/2 + +• The sequence of characters of the value returned by S'Image when some of the graphic + +characters of S'Wide_Wide_Image are not defined in Character. See 3.5(37/3). + +13 + +14 + +15 + +16 + +17 + +18 + +19 + +20/2 + +20.1/2 + +• The predefined integer types declared in Standard. See 3.5.4(25). +• Any nonstandard integer types and the operators defined for them. See 3.5.4(26). +• Any nonstandard real types and the operators defined for them. See 3.5.6(8). +• What combinations of requested decimal precision and range are supported for floating point + +types. See 3.5.7(7). + +• The predefined floating point types declared in Standard. See 3.5.7(16). +• The small of an ordinary fixed point type. See 3.5.9(8/2). +• What combinations of small, range, and digits are supported for fixed point types. See 3.5.9(10). +• The result of Tags.Wide_Wide_Expanded_Name for types declared within an unnamed + +block_statement. See 3.9(10). + +• The sequence of characters of the value returned by Tags.Expanded_Name (respectively, +of +some +Tags.Wide_Expanded_Name) +Tags.Wide_Wide_Expanded_Name are not defined in Character (respectively, Wide_Character). +See 3.9(10.1/2). + +characters + +graphic + +when + +the + +of + +21 + +21.1/2 + +• Implementation-defined attributes. See 4.1.4(12/1). +• Rounding of real static expressions which are exactly half-way between two machine numbers. + +See 4.9(38/2). + +22 + +23 + +24 + +25/2 + +26 + +26.1/2 + +27/3 + +28 + +29 + +30 + +• Any implementation-defined time types. See 9.6(6/3). +• The time base associated with relative delays. See 9.6(20). +• The time base of the type Calendar.Time. See 9.6(23). +• The time zone used for package Calendar operations. See 9.6(24/2). +• Any limit on delay_until_statements of select_statements. See 9.6(29). +• The result of Calendar.Formating.Image if its argument represents more than 100 hours. See + +9.6.1(86/2). + +• This paragraph was deleted. +• The representation for a compilation. See 10.1(2). +• Any restrictions on compilations that contain multiple compilation_units. See 10.1(4). +• The mechanisms for creating an environment and for adding and replacing compilation units. + +See 10.1.4(3/2). + +30.1/2 + +• The mechanisms for adding a compilation unit mentioned in a limited_with_clause to an + +environment. See 10.1.4(3/2). + +31 + +32 + +33 + +34 + +35 + +• The manner of explicitly assigning library units to a partition. See 10.2(2). +• The implementation-defined means, if any, of specifying which compilation units are needed by + +a given compilation unit. See 10.2(2). + +• The manner of designating the main subprogram of a partition. See 10.2(7). +• The order of elaboration of library_items. See 10.2(18). +• Parameter passing and function return for the main subprogram. See 10.2(21). + +M.2 Implementation-Defined Characteristics + +13 December 2012 788 + + Ada Reference Manual — 2012 Edition + +• The mechanisms for building and running partitions. See 10.2(24). +• The details of program execution, including program termination. See 10.2(25). +• The semantics of any nonactive partitions supported by the implementation. See 10.2(28/3). +• The information returned by Exception_Message. See 11.4.1(10.1/3). +• The result of Exceptions.Wide_Wide_Exception_Name for exceptions declared within an + +unnamed block_statement. See 11.4.1(12). + +• The sequence of characters of the value returned by Exceptions.Exception_Name (respectively, +of +(respectively, + +Exceptions.Wide_Exception_Name) when +Exceptions.Wide_Wide_Exception_Name are not defined +Wide_Character). See 11.4.1(12.1/2). + +graphic +in Character + +characters + +some + +the + +of + +• The information returned by Exception_Information. See 11.4.1(13/2). +• Implementation-defined policy_identifiers and assertion_aspect_marks allowed in a pragma + +Assertion_Policy. See 11.4.2(9/3). + +• The default assertion policy. See 11.4.2(10). +• Implementation-defined check names. See 11.5(27). +• Existence and meaning of second parameter of pragma Unsuppress. See 11.5(27.1/2). +• The cases that cause conflicts between the representation of the ancestors of a type_declaration. + +See 13.1(13.1/3). + +• The interpretation of each representation aspect. See 13.1(20). +• Any restrictions placed upon the specification of representation aspects. See 13.1(20). +• Implementation-defined aspects, inluding the syntax for specifying such aspects and the legality + +rules for such aspects. See 13.1.1(38). +• The set of machine scalars. See 13.3(8.1/3). +• The meaning of Size for indefinite subtypes. See 13.3(48). +• The default external representation for a type tag. See 13.3(75/3). +• What determines whether a compilation unit is the same in two different partitions. See 13.3(76). +• Implementation-defined components. See 13.5.1(15). +• If Word_Size = Storage_Unit, the default bit ordering. See 13.5.3(5). +• The contents of the visible part of package System. See 13.7(2). +• The + +of +Storage_Elements.Storage_Offset, +Storage_Elements.Storage_Element, and the declaration of Storage_Elements.Integer_Address.. +See 13.7.1(11). + +modulus + +range + +the + +of + +36 + +37 + +38 + +39 + +40/2 + +40.1/2 + +41 + +41.1/3 + +41.2/2 + +42 + +42.1/2 + +42.2/2 + +43/3 + +44/3 + +44.1/3 + +44.2/2 + +45 + +46 + +47 + +48 + +49 + +50/2 + +50.1/2 + +• The contents of the visible part of package System.Machine_Code, and the meaning of + +51 + +code_statements. See 13.8(7). + +• The result of unchecked conversion for instances with scalar result types whose result is not + +51.1/2 + +defined by the language. See 13.9(11). + +• The effect of unchecked conversion for instances with nonscalar result types whose effect is not + +defined by the language. See 13.9(11). + +• This paragraph was deleted. + +52/2 + +53/2 + +789 13 December 2012 + +Implementation-Defined Characteristics M.2 + + Ada Reference Manual — 2012 Edition + +54 + +• Whether or not the implementation provides user-accessible names for the standard pool type(s). + +See 13.11(17). + +55/2 + +• The meaning of Storage_Size when neither the Storage_Size nor the Storage_Pool is specified + +for an access type. See 13.11(18). + +56/2 + +57/3 + +57.1/3 + +58 + +58.1/3 + +59/2 + +• This paragraph was deleted. +• This paragraph was deleted. +• Implementation-defined restrictions allowed in a pragma Restrictions. See 13.12(8.7/3). +• The consequences of violating limitations on Restrictions pragmas. See 13.12(9). +• Implementation-defined usage profiles allowed in a pragma Profile. See 13.12(15). +• The contents of the stream elements read and written by the Read and Write attributes of + +elementary types. See 13.13.2(9). + +60 + +• The names and characteristics of the numeric subtypes declared in the visible part of package + +Standard. See A.1(3). + +60.1/2 + +61 + +62 + +63 + +64 + +65/2 + +66 + +67/2 + +68 + +69/2 + +70 + +71/2 + +72 + +72.1/1 + +73/2 + +73.1/2 + +73.2/2 + +73.3/2 + +73.4/2 + +73.5/2 + +• The values returned by Strings.Hash. See A.4.9(3/2). +• The accuracy actually achieved by the elementary functions. See A.5.1(1). +• The + +the operators or +Numerics.Generic_Elementary_Functions, when Float_Type'Signed_Zeros +A.5.1(46). + +some of + +sign of + +result + +from + +zero + +a + +functions + +in +is True. See + +• The value of Numerics.Float_Random.Max_Image_Width. See A.5.2(27). +• The value of Numerics.Discrete_Random.Max_Image_Width. See A.5.2(27). +• This paragraph was deleted. +• The string representation of a random number generator's state. See A.5.2(38). +• This paragraph was deleted. +• The values of the Model_Mantissa, Model_Emin, Model_Epsilon, Model, Safe_First, and + +Safe_Last attributes, if the Numerics Annex is not supported. See A.5.3(72). + +• This paragraph was deleted. +• The value of Buffer_Size in Storage_IO. See A.9(10). +• The external files associated with the standard input, standard output, and standard error files. + +See A.10(5). + +• The accuracy of the value produced by Put. See A.10.9(36). +• Current size for a stream file for which positioning is not supported. See A.12.1(1.1/1). +• The meaning of Argument_Count, Argument, and Command_Name +Command_Line. The bounds of type Command_Line.Exit_Status. See A.15(1). + +for package + +• The interpretation of file names and directory names. See A.16(46/2). +• The maximum value for a file size in Directories. See A.16(87/2). +• The result for Directories.Size for a directory or special file See A.16(93/2). +• The result for Directories.Modification_Time for a directory or special file. See A.16(95/2). +• The interpretation of a nonnull search pattern in Directories. See A.16(104/3). + +M.2 Implementation-Defined Characteristics + +13 December 2012 790 + + Ada Reference Manual — 2012 Edition + +• The results of a Directories search if the contents of the directory are altered while a search is in + +73.6/2 + +progress. See A.16(110/3). + +• The definition and meaning of an environment variable. See A.17(1/2). +• The circumstances where an environment variable cannot be defined. See A.17(16/2). +• Environment names for which Set has the effect of Clear. See A.17(17/2). +• The value of Containers.Hash_Type'Modulus. The value of Containers.Count_Type'Last. See + +73.7/2 + +73.8/2 + +73.9/2 + +73.10/2 + +A.18.1(7/2). + +• Implementation-defined convention names. See B.1(11/3). +• The meaning of link names. See B.1(36). +• The manner of choosing link names when neither the link name nor the address of an imported + +or exported entity is specified. See B.1(36). + +• The effect of pragma Linker_Options. See B.1(37). +• The contents of the visible part of package Interfaces and its language-defined descendants. See + +B.2(1). + +• Implementation-defined children of package Interfaces. See B.2(11). +• The definitions of certain types and constants in Interfaces.C. See B.3(41). +• The + +types Floating, Long_Floating, Binary, Long_Binary, Decimal_Element, + +and +the variables Ada_To_COBOL and + +COBOL_Character; and +COBOL_To_Ada, in Interfaces.COBOL. See B.4(50). + +initializations of + +the + +• The types Fortran_Integer, Real, Double_Precision, and Character_Set in Interfaces.Fortran. See + +B.5(17). + +• Implementation-defined intrinsic subprograms. See C.1(1/3). +• This paragraph was deleted. +• This paragraph was deleted. +• Any restrictions on a protected procedure or its containing type when an aspect Attach_handler + +or Interrupt_Handler is specified. See C.3.1(17). + +• Any other forms of interrupt handler supported by the Attach_Handler and Interrupt_Handler + +aspects. See C.3.1(19). +• This paragraph was deleted. +• The semantics of pragma Discard_Names. See C.5(7). +• The result of the Task_Identification.Image attribute. See C.7.1(7). +• The value of Current_Task when in a protected entry, interrupt handler, or finalization of a task + +attribute. See C.7.1(17/3). +• This paragraph was deleted. +• Granularity of locking for Task_Attributes. See C.7.2(16/1). +• This paragraph was deleted. +• This paragraph was deleted. +• The declarations of Any_Priority and Priority. See D.1(11). +• Implementation-defined execution resources. See D.1(15). + +791 13 December 2012 + +Implementation-Defined Characteristics M.2 + +74 + +75 + +76 + +77 + +78 + +79/2 + +79.1/2 + +80/1 + +80.1/1 + +81/2 + +82/2 + +83/2 + +83.1/3 + +83.2/3 + +84/2 + +85 + +86 + +87/2 + +88/2 + +88.1/1 + +89/2 + +90/2 + +91 + +92 + + Ada Reference Manual — 2012 Edition + +93 + +• Whether, on a multiprocessor, a task that is waiting for access to a protected object keeps its + +processor busy. See D.2.1(3). + +94/2 + +95/2 + +96/2 + +97/2 + +97.1/2 + +98 + +98.1/2 + +99 + +100 + +101 + +102/2 + +103 + +103.1/2 + +103.2/2 + +103.3/2 + +103.4/2 + +104/2 + +105/2 + +106/2 + +106.1/3 + +106.2/3 + +107/2 + +107.1/3 + +107.2/3 + +107.3/3 + +107.4/3 + +• The effect of implementation-defined execution resources on task dispatching. See D.2.1(9/2). +• This paragraph was deleted. +• This paragraph was deleted. +• Implementation defined task dispatching policies. See D.2.2(19). +• The value of Default_Quantum in Dispatching.Round_Robin. See D.2.5(4). +• Implementation-defined policy_identifiers allowed in a pragma Locking_Policy. See D.3(4). +• The locking policy if no Locking_Policy pragma applies to any unit of a partition. See D.3(6). +• Default ceiling priorities. See D.3(10/3). +• The ceiling of any protected object used internally by the implementation. See D.3(16). +• Implementation-defined queuing policies. See D.4(1/3). +• This paragraph was deleted. +• Any operations that implicitly require heap storage allocation. See D.7(8). +• When restriction No_Task_Termination applies to a partition, what happens when a task + +terminates. See D.7(15.1/2). + +• The behavior when restriction Max_Storage_At_Blocking is violated. See D.7(17/1). +• The behavior when restriction Max_Asynchronous_Select_Nesting is violated. See D.7(18/1). +• The behavior when restriction Max_Tasks is violated. See D.7(19). +• Whether the use of pragma Restrictions results in a reduction in program code or data size or + +execution time. See D.7(20). + +• This paragraph was deleted. +• This paragraph was deleted. +• The value of Barrier_Limit'Last in Synchronous_Barriers. See D.10.1(4/3). +• When an aborted task that is waiting on a Synchronous_Barrier is aborted. See D.10.1(13/3). +• This paragraph was deleted. +• The processor on which a task with a CPU value of a Not_A_Specific_CPU will execute when + +the Ravenscar profile is in effect. See D.13(8). + +• The value of Min_Handler_Ceiling in Execution_Time.Group_Budgets. See D.14.2(7/2). +• The value of CPU_Range'Last in System.Multiprocessors. See D.16(4/3). +• The processor on which the environment task executes in the absence of a value for the aspect + +CPU. See D.16(13/3). + +108 + +109 + +110 + +• The means for creating and executing distributed programs. See E(5). +• Any events that can result in a partition becoming inaccessible. See E.1(7). +• The scheduling policies, treatment of priorities, and management of shared resources between + +partitions in certain cases. See E.1(11). + +111/1 + +• This paragraph was deleted. + +M.2 Implementation-Defined Characteristics + +13 December 2012 792 + + • Whether the execution of the remote subprogram is immediately aborted as a result of + +112 + +cancellation. See E.4(13). + +Ada Reference Manual — 2012 Edition + +• The range of type System.RPC.Partition_Id. See E.5(14). +• This paragraph was deleted. +• Implementation-defined interfaces in the PCS. See E.5(26). +• The values of named numbers in the package Decimal. See F.2(7). +• The value of Max_Picture_Length in the package Text_IO.Editing See F.3.3(16). +• The value of Max_Picture_Length in the package Wide_Text_IO.Editing See F.3.4(5). +• The value of Max_Picture_Length in the package Wide_Wide_Text_IO.Editing See F.3.5(5). +• The accuracy actually achieved by the complex elementary functions and by other complex + +arithmetic operations. See G.1(1). + +• The sign of a zero result (or a component thereof) from any operator or function in + +Numerics.Generic_Complex_Types, when Real'Signed_Zeros is True. See G.1.1(53). + +• The sign of a zero result (or a component thereof) from any operator or function in +Numerics.Generic_Complex_Elementary_Functions, when Complex_Types.Real'Signed_Zeros +is True. See G.1.2(45). + +• Whether the strict mode or the relaxed mode is the default. See G.2(2). +• The result interval in certain cases of fixed-to-float conversion. See G.2.1(10). +• The result of a floating point arithmetic operation in overflow situations, when the + +Machine_Overflows attribute of the result type is False. See G.2.1(13). + +• The result interval for division (or exponentiation by a negative exponent), when the floating + +point hardware implements division as multiplication by a reciprocal. See G.2.1(16). + +• The definition of close result set, which determines the accuracy of certain fixed point + +multiplications and divisions. See G.2.3(5). + +• Conditions on a universal_real operand of a fixed point multiplication or division for which the + +result shall be in the perfect result set. See G.2.3(22). +• The result of a fixed point arithmetic operation + +in overflow situations, when + +the + +Machine_Overflows attribute of the result type is False. See G.2.3(27). + +• The result of an elementary function reference + +in overflow situations, when + +the + +Machine_Overflows attribute of the result type is False. See G.2.4(4). + +• The value of the angle threshold, within which certain elementary functions, complex arithmetic +operations, and complex elementary functions yield results conforming to a maximum relative +error bound. See G.2.4(10). + +• The accuracy of certain elementary functions for parameters beyond the angle threshold. See + +G.2.4(10). + +• The result of a complex arithmetic operation or complex elementary function reference in +overflow situations, when the Machine_Overflows attribute of the corresponding real type is +False. See G.2.6(5). + +• The accuracy of certain complex arithmetic operations and certain complex elementary functions + +for parameters (or components thereof) beyond the angle threshold. See G.2.6(8). + +112.1/2 + +113/2 + +114 + +115 + +116 + +117 + +117.1/2 + +118 + +119 + +120 + +121 + +122 + +123 + +124 + +125 + +126 + +127 + +128 + +129 + +130 + +131 + +132 + +• The accuracy requirements for the subprograms Solve, Inverse, Determinant, Eigenvalues and + +132.1/2 + +Eigensystem for type Real_Matrix. See G.3.1(81/2). + +793 13 December 2012 + +Implementation-Defined Characteristics M.2 + + Ada Reference Manual — 2012 Edition + +132.2/2 + +• The accuracy requirements for the subprograms Solve, Inverse, Determinant, Eigenvalues and + +Eigensystem for type Complex_Matrix. See G.3.2(149/2). + +133/2 + +134/2 + +135/2 + +136/2 + +136.1/2 + +• This paragraph was deleted. +• This paragraph was deleted. +• This paragraph was deleted. +• This paragraph was deleted. +• Implementation-defined policy_identifiers allowed in a pragma Partition_Elaboration_Policy. + +See H.6(4/2). + +M.3 Implementation Advice + +1/2 + +2/2 + +3/2 + +4/2 + +5/2 + +6/2 + +7/2 + +8/2 + +9/2 + +This International Standard sometimes gives advice about handling certain target machine dependences. +Each Ada implementation must document whether that advice is followed: + +• Program_Error should be raised when an unsupported Specialized Needs Annex feature is used + +at run time. See 1.1.3(20). + +• Implementation-defined extensions to the functionality of a language-defined library unit should + +be provided by adding children to the library unit. See 1.1.3(21). + +• If a bounded error or erroneous execution is detected, Program_Error should be raised. See + +1.1.5(12). + +• Implementation-defined pragmas should have no semantic effect for error-free programs. See + +2.8(16/3). + +• Implementation-defined pragmas should not make an illegal program legal, unless they complete + +a declaration or configure the library_items in an environment. See 2.8(19). + +• Long_Integer should be declared in Standard if the target supports 32-bit arithmetic. No other + +named integer subtypes should be declared in Standard. See 3.5.4(28). + +• For a two's complement target, modular types with a binary modulus up to System.Max_Int*2+2 +should be supported. A nonbinary modulus up to Integer'Last should be supported. See +3.5.4(29). + +• Program_Error should be raised for the evaluation of S'Pos for an enumeration type, if the value +of the operand does not correspond to the internal code for any enumeration literal of the type. +See 3.5.5(8). + +10/2 + +• Long_Float should be declared in Standard if the target supports 11 or more digits of precision. + +No other named float subtypes should be declared in Standard. See 3.5.7(17). + +11/2 + +• Multidimensional arrays should be represented in row-major order, unless the array has + +convention Fortran. See 3.6.2(11/3). + +12/3 + +• Tags.Internal_Tag should return the tag of a type, if one exists, whose innermost master is a + +master of the point of the function call.. See 3.9(26.1/3). + +13/2 + +• A real static expression with a nonformal type that is not part of a larger static expression should + +be rounded the same as the target system. See 4.9(38.1/2). + +14/2 + +15/2 + +• The value of Duration'Small should be no greater than 100 microseconds. See 9.6(30). +• The time base for delay_relative_statements should be monotonic. See 9.6(31). + +M.2 Implementation-Defined Characteristics + +13 December 2012 794 + + Ada Reference Manual — 2012 Edition + +• Leap seconds should be supported if the target system supports them. Otherwise, operations in +Calendar.Formatting should return results consistent with no leap seconds. See 9.6.1(89/2). +• When applied to a generic unit, a program unit pragma that is not a library unit pragma should +apply to each instance of the generic unit for which there is not an overriding pragma applied +directly to the instance. See 10.1.5(10/1). + +• A type declared in a preelaborated package should have the same representation in every + +elaboration of a given version of the package. See 10.2.1(12). + +• Exception_Information should provide information useful for debugging, and should include the + +Exception_Name and Exception_Message. See 11.4.1(19). + +• Exception_Message by default should be short, provide information useful for debugging, and + +should not include the Exception_Name. See 11.4.1(19). + +• Code executed for checks that have been suppressed should be minimized. See 11.5(28). +• The recommended level of support for all representation items should be followed. See + +13.1(28/3). + +• Storage allocated to objects of a packed type should be minimized. See 13.2(6). +• The recommended level of support for the Pack aspect should be followed. See 13.2(9). +• For an array X, X'Address should point at the first component of the array rather than the array + +bounds. See 13.3(14). + +• The recommended level of support for the Address attribute should be followed. See 13.3(19). +• For any tagged specific subtype S, S'Class'Alignment should equal S'Alignment. See 13.3(28). +• The recommended level of support for the Alignment attribute should be followed. See 13.3(35). +• The Size of an array object should not include its bounds. See 13.3(41.1/2). +• If the Size of a subtype allows for efficient independent addressability, then the Size of most + +objects of the subtype should equal the Size of the subtype. See 13.3(52). + +• A Size clause on a composite subtype should not affect the internal layout of components. See + +13.3(53). + +• The recommended level of support for the Size attribute should be followed. See 13.3(56). +• The recommended level of support for the Component_Size attribute should be followed. See + +13.3(73). + +• The recommended level of support for enumeration_representation_clauses should be + +followed. See 13.4(10). + +• The recommended level of support for record_representation_clauses should be followed. See + +13.5.1(22). + +• If a component is represented using a pointer to the actual data of the component which is +contiguous with the rest of the object, then the storage place attributes should reflect the place of +the actual data. If a component is allocated discontiguously from the rest of the object, then a +warning should be generated upon reference to one of its storage place attributes. See 13.5.2(5). +• The recommended level of support for the nondefault bit ordering should be followed. See + +13.5.3(8). + +• Type System.Address should be a private type. See 13.7(37). +• Operations in System and its children should reflect the target environment; operations that do + +not make sense should raise Program_Error. See 13.7.1(16). + +16/2 + +17/2 + +18/2 + +19/2 + +20/2 + +21/2 + +22/2 + +23/2 + +24/3 + +25/2 + +26/2 + +26.1/3 + +27/2 + +28/2 + +29/2 + +30/2 + +31/2 + +32/2 + +33/2 + +34/2 + +35/2 + +36/2 + +37/2 + +38/2 + +795 13 December 2012 + +Implementation Advice M.3 + + Ada Reference Manual — 2012 Edition + +39/2 + +• Since the Size of an array object generally does not include its bounds, the bounds should not be + +part of the converted data in an instance of Unchecked_Conversion. See 13.9(14/2). + +40/2 + +• There should not be unnecessary run-time checks on the result of an Unchecked_Conversion; the +result should be returned by reference when possible. Restrictions on Unchecked_Conversions +should be avoided. See 13.9(15). + +41/2 + +• The recommended level of support for Unchecked_Conversion should be followed. See + +13.9(17). + +42/2 + +• Any cases in which heap storage is dynamically allocated other than as part of the evaluation of + +an allocator should be documented. See 13.11(23). + +43/2 + +• A default storage pool for an access-to-constant type should not have overhead to support + +deallocation of individual objects. See 13.11(24). + +44/2 + +• Usually, a storage pool for an access discriminant or access parameter should be created at the +point of an allocator, and be reclaimed when the designated object becomes inaccessible. For +other anonymous access types, the pool should be created at the point where the type is +elaborated and need not support deallocation of individual objects. See 13.11(25). + +45/2 + +• For a standard storage pool, an instance of Unchecked_Deallocation should actually reclaim the + +storage. See 13.11.2(17). + +45.1/3 + +46/2 + +• A call on an instance of Unchecked_Deallocation with a nonnull access value should raise +Program_Error if the actual access type of the instance is a type for which the Storage_Size has +been specified to be zero or is defined by the language to be zero. See 13.11.2(17.1/3). + +• If not specified, the value of Stream_Size for an elementary type should be the number of bits +that corresponds to the minimum number of stream elements required by the first subtype of the +type, rounded up to the nearest factor or multiple of the word size that is also a multiple of the +stream element size. See 13.13.2(1.6/2). + +47/2 + +• The recommended level of support for the Stream_Size attribute should be followed. See + +13.13.2(1.8/2). + +48/2 + +49/2 + +• If an implementation provides additional named predefined integer types, then the names should +end with “Integer”. If an implementation provides additional named predefined floating point +types, then the names should end with “Float”. See A.1(52). + +• Implementation-defined operations on Wide_Character, Wide_String, Wide_Wide_Character, +and Wide_Wide_String should be child units of Wide_Characters or Wide_Wide_Characters. +See A.3.1(7/3). + +49.1/3 + +• The string returned by Wide_Characters.Handling.Character_Set_Version should include either + +“10646:” or “Unicode”. See A.3.5(62). + +50/2 + +• Bounded string objects should not be implemented by implicit pointers and dynamic allocation. + +See A.4.4(106). + +51/2 + +• Strings.Hash should be good a hash function, returning a wide spread of values for different + +string values, and similar strings should rarely return the same value. See A.4.9(12/2). + +51.1/3 + +• If an implementation supports other string encoding schemes, a child of Ada.Strings similar to + +UTF_Encoding should be defined. See A.4.11(107/3). + +52/2 + +• Any storage associated with an object of type Generator of the random number packages should + +be reclaimed on exit from the scope of the object. See A.5.2(46). + +53/2 + +• Each value of Initiator passed to Reset for the random number packages should initiate a distinct +sequence of random numbers, or, if that is not possible, be at least a rapidly varying function of +the initiator value. See A.5.2(47). + +M.3 Implementation Advice + +13 December 2012 796 + + Ada Reference Manual — 2012 Edition + +• Get_Immediate should be implemented with unbuffered input; input should be available + +immediately; line-editing should be disabled. See A.10.7(23). + +• Package Directories.Information should be provided to retrieve other information about a file. + +See A.16(124/2). + +• Directories.Start_Search and Directories.Search should raise Name_Error for malformed + +patterns. See A.16(125). + +• Directories.Rename should be supported at least when both New_Name and Old_Name are + +simple names and New_Name does not identify an existing external file. See A.16(126/2). + +54/2 + +55/2 + +56/3 + +57/2 + +• Directories.Hierarchical_File_Names should be provided for systems with hierarchical file + +57.1/3 + +naming, and should not be provided on other systems. See A.16.1(36/3). + +• If the execution environment supports subprocesses, the current environment variables should be + +used to initialize the environment variables of a subprocess. See A.17(32/2). + +• Changes to the environment variables made outside the control of Environment_Variables + +should be reflected immediately. See A.17(33/2). + +• Containers.Hash_Type'Modulus should be at least 2**32. Containers.Count_Type'Last should + +be at least 2**31–1. See A.18.1(8/2). + +• The worst-case time complexity of Element for Containers.Vector should be O(log N). See + +A.18.2(256/2). + +• The worst-case time complexity of Append with Count = 1 when N is less than the capacity for + +Containers.Vector should be O(log N). See A.18.2(257/2). + +• The worst-case time complexity of Prepend with Count = 1 and Delete_First with Count=1 for + +Containers.Vectors should be O(N log N). See A.18.2(258/2). + +• The worst-case + +instance of +Containers.Vectors.Generic_Sorting should be O(N**2), and the average time complexity +should be better than O(N**2). See A.18.2(259/2). + +time complexity of a call on procedure Sort of an + +• Containers.Vectors.Generic_Sorting.Sort and Containers.Vectors.Generic_Sorting.Merge should + +minimize copying of elements. See A.18.2(260/2). + +• Containers.Vectors.Move should not copy elements, and should minimize copying of internal + +data structures. See A.18.2(261/2). + +• If an exception is propagated from a vector operation, no storage should be lost, nor any + +elements removed from a vector unless specified by the operation. See A.18.2(262/2). + +• The worst-case time complexity of Element, Insert with Count=1, and Delete with Count=1 for + +Containers.Doubly_Linked_Lists should be O(log N). See A.18.3(160/2). + +• A call on procedure Sort of an instance of Containers.Doubly_Linked_Lists.Generic_Sorting +should have an average time complexity better than O(N**2) and worst case no worse than +O(N**2). See A.18.3(161/2). + +• Containers.Doubly_Linked_Lists.Move should not copy elements, and should minimize copying + +of internal data structures. See A.18.3(162/2). + +• If an exception is propagated from a list operation, no storage should be lost, nor any elements + +removed from a list unless specified by the operation. See A.18.3(163/2). + +• Move for a map should not copy elements, and should minimize copying of internal data + +structures. See A.18.4(83/2). + +797 13 December 2012 + +Implementation Advice M.3 + +58/2 + +59/2 + +60/2 + +61/2 + +62/2 + +63/2 + +64/2 + +65/2 + +66/2 + +67/2 + +68/2 + +69/2 + +70/2 + +71/2 + +72/2 + + Ada Reference Manual — 2012 Edition + +73/2 + +• If an exception is propagated from a map operation, no storage should be lost, nor any elements + +removed from a map unless specified by the operation. See A.18.4(84/2). + +74/2 + +75/2 + +• The average time complexity of Element, Insert, Include, Replace, Delete, Exclude and Find +operations that take a key parameter for Containers.Hashed_Maps should be O(log N). The +average time complexity of the subprograms of Containers.Hashed_Maps that take a cursor +parameter +of +The +Containers.Hashed_Maps.Reserve_Capacity should be O(N). See A.18.5(62/2). + +complexity + +average + +should + +O(1). + +time + +be + +• The worst-case time complexity of Element, Insert, Include, Replace, Delete, Exclude and Find +operations that take a key parameter for Containers.Ordered_Maps should be O((log N)**2) or +better. The worst-case time complexity of the subprograms of Containers.Ordered_Maps that +take a cursor parameter should be O(1). See A.18.6(95/2). + +76/2 + +• Move for sets should not copy elements, and should minimize copying of internal data + +structures. See A.18.7(104/2). + +77/2 + +• If an exception is propagated from a set operation, no storage should be lost, nor any elements + +removed from a set unless specified by the operation. See A.18.7(105/2). + +78/2 + +79/2 + +79.1/3 + +• The average time complexity of the Insert, Include, Replace, Delete, Exclude and Find +operations of Containers.Hashed_Sets that take an element parameter should be O(log N). The +average time complexity of the subprograms of Containers.Hashed_Sets that take a cursor +parameter should be O(1). The average time complexity of Containers.Hashed_Sets.- +Reserve_Capacity should be O(N). See A.18.8(88/2). + +• The worst-case time complexity of the Insert, Include, Replace, Delete, Exclude and Find +operations of Containers.Ordered_Sets that take an element parameter should be O((log N)**2). +The worst-case time complexity of the subprograms of Containers.Ordered_Sets that take a +cursor parameter should be O(1). See A.18.9(116/2). + +• The worst-case time complexity of the Element, Parent, First_Child, Last_Child, Next_Sibling, +of + +Previous_Sibling, +Containers.Multiway_Trees should be O(log N). See A.18.10(231/3). + +Insert_Child + +operations + +Count=1, + +Delete + +with + +and + +79.2/3 + +• Containers.Multiway_Trees.Move should not copy elements, and should minimize copying of + +internal data structures. See A.18.10(232/3). + +79.3/3 + +• If an exception is propagated from a tree operation, no storage should be lost, nor any elements + +removed from a tree unless specified by the operation. See A.18.10(233/3). + +79.4/3 + +• Containers.Indefinite_Holders.Move should not copy the element, and should minimize copying + +of internal data structures. See A.18.18(73/3). + +79.5/3 + +• If an exception is propagated from a holder operation, no storage should be lost, nor should the +element be removed from a holder container unless specified by the operation. See +A.18.18(74/3). + +79.6/3 + +• Bounded vector objects should be implemented without implicit pointers or dynamic allocation. + +See A.18.19(16/3). + +79.7/3 + +• The implementation advice for procedure Move to minimize copying does not apply to bounded + +vectors. See A.18.19(17/3). + +79.8/3 + +• Bounded list objects should be implemented without implicit pointers or dynamic allocation. See + +A.18.20(19/3). + +79.9/3 + +• The implementation advice for procedure Move to minimize copying does not apply to bounded + +lists. See A.18.20(20/3). + +M.3 Implementation Advice + +13 December 2012 798 + + Ada Reference Manual — 2012 Edition + +• Bounded hashed map objects should be implemented without implicit pointers or dynamic + +79.10/3 + +allocation. See A.18.21(21/3). + +• The implementation advice for procedure Move to minimize copying does not apply to bounded + +79.11/3 + +hashed maps. See A.18.21(22/3). + +• Bounded ordered map objects should be implemented without implicit pointers or dynamic + +79.12/3 + +allocation. See A.18.22(18/3). + +• The implementation advice for procedure Move to minimize copying does not apply to bounded + +79.13/3 + +ordered maps. See A.18.22(19/3). + +• Bounded hashed set objects should be implemented without implicit pointers or dynamic + +79.14/3 + +allocation. See A.18.23(20/3). + +• The implementation advice for procedure Move to minimize copying does not apply to bounded + +79.15/3 + +hashed sets. See A.18.23(21/3). + +• Bounded ordered set objects should be implemented without implicit pointers or dynamic + +79.16/3 + +allocation. See A.18.24(17/3). + +• The implementation advice for procedure Move to minimize copying does not apply to bounded + +79.17/3 + +ordered sets. See A.18.24(18/3). + +• Bounded tree objects should be implemented without implicit pointers or dynamic allocation. + +79.18/3 + +See A.18.25(19/3). + +• The implementation advice for procedure Move to minimize copying does not apply to bounded + +79.19/3 + +trees. See A.18.25(20/3). + +• Containers.Generic_Array_Sort and Containers.Generic_Constrained_Array_Sort should have +an average time complexity better than O(N**2) and worst case no worse than O(N**2). See +A.18.26(10/2). + +80/2 + +• Containers.Generic_Array_Sort + +and Containers.Generic_Constrained_Array_Sort + +should + +81/2 + +minimize copying of elements. See A.18.26(11/2). + +• Containers.Generic_Sort should have an average time complexity better than O(N**2) and worst + +case no worse than O(N**2). See A.18.26(12/3). + +• Containers.Generic_Sort should minimize calls to the generic formal Swap. See A.18.26(13/3). +• Bounded queue objects should be implemented without implicit pointers or dynamic allocation. + +See A.18.29(13/3). + +• Bounded priority queue objects should be implemented without implicit pointers or dynamic + +allocation. See A.18.31(14/3). + +• If Export is supported for a language, the main program should be able to be written in that +language. Subprograms named "adainit" and "adafinal" should be provided for elaboration and +finalization of the environment task. See B.1(39/3). + +• Automatic elaboration of preelaborated packages should be provided when specifying the Export + +aspect as True is supported. See B.1(40/3). + +• For each supported convention L other than Intrinsic, specifying the aspects Import and Export +should be supported for objects of L-compatible types and for subprograms, and aspect +Convention should be supported for L-eligible types and for subprograms. See B.1(41/3). + +• If an interface to C, COBOL, or Fortran is provided, the corresponding package or packages +described in Annex B, “Interface to Other Languages” should also be provided. See B.2(13/3). + +81.1/3 + +81.2/3 + +81.3/3 + +81.4/3 + +82/3 + +83/3 + +84/3 + +85/2 + +799 13 December 2012 + +Implementation Advice M.3 + + Ada Reference Manual — 2012 Edition + +86/2 + +• The constants nul, wide_nul, char16_nul, and char32_nul in package Interfaces.C should have a + +representation of zero. See B.3(62.5/3). + +87/2 + +• If C interfacing is supported, the interface correspondences between Ada and C should be + +supported. See B.3(71). + +88/2 + +• If COBOL interfacing is supported, the interface correspondences between Ada and COBOL + +should be supported. See B.4(98). + +89/2 + +• If Fortran interfacing is supported, the interface correspondences between Ada and Fortran + +should be supported. See B.5(26). + +90/2 + +• The machine code or intrinsics support should allow access to all operations normally available + +to assembly language programmers for the target environment. See C.1(3). + +91/2 + +• Interface to assembler should be supported; the default assembler should be associated with the + +convention identifier Assembler. See C.1(4/3). + +92/2 + +• If an entity is exported to assembly language, then the implementation should allocate it at an +addressable location even if not otherwise referenced from the Ada code. A call to a machine +code or assembler subprogram should be treated as if it could read or update every object that is +specified as exported. See C.1(5). + +93/2 + +• Little or no overhead should be associated with calling intrinsic and machine-code subprograms. + +See C.1(10). + +94/2 + +• Intrinsic subprograms should be provided to access any machine operations that provide special + +capabilities or efficiency not normally available. See C.1(16). + +95/2 + +96/2 + +97/2 + +98/2 + +• If the Ceiling_Locking policy is not in effect and the target system allows for finer-grained +control of interrupt blocking, a means for the application to specify which interrupts are to be +blocked during protected actions should be provided. See C.3(28/2). + +• Interrupt handlers should be called directly by the hardware. See C.3.1(20). +• Violations of any implementation-defined restrictions on interrupt handlers should be detected + +before run time. See C.3.1(21). + +• If implementation-defined forms of interrupt handler procedures are supported, then for each +such form of a handler, a type analogous to Parameterless_Handler should be specified in a child +package of Interrupts, with the same operations as in the predefined package Interrupts. See +C.3.2(25). + +99/2 + +• Preelaborated packages should be implemented such that little or no code is executed at run time + +for the elaboration of entities. See C.4(14). + +100/2 + +• If pragma Discard_Names applies to an entity, then the amount of storage used for storing + +names associated with that entity should be reduced. See C.5(8). + +101/2 + +• A load or store of a volatile object whose size is a multiple of System.Storage_Unit and whose +alignment is nonzero, should be implemented by accessing exactly the bits of the object and no +others. See C.6(22/2). + +102/2 + +• A load or store of an atomic object should be implemented by a single load or store instruction. + +See C.6(23/2). + +103/2 + +• If the target domain requires deterministic memory use at run time, storage for task attributes +should be pre-allocated statically and the number of attributes pre-allocated should be +documented. See C.7.2(30). + +104/2 + +• Finalization of task attributes and reclamation of associated storage should be performed as soon + +as possible after task termination. See C.7.2(30.1/2). + +M.3 Implementation Advice + +13 December 2012 800 + + Ada Reference Manual — 2012 Edition + +• Names that end with “_Locking” should be used for implementation-defined locking policies. + +See D.3(17). + +• Names that end with “_Queuing” should be used for implementation-defined queuing policies. + +See D.4(16). + +• The abort_statement should not require the task executing the statement to block. See D.6(9). +• On a multi-processor, the delay associated with aborting a task on another processor should be + +bounded. See D.6(10). + +• When feasible, specified restrictions should be used to produce a more efficient implementation. + +See D.7(21). + +• When appropriate, mechanisms to change the value of Tick should be provided. See D.8(47). +• Calendar.Clock and Real_Time.Clock should be transformations of the same time base. See + +D.8(48). + +• The “best” time base which exists in the underlying system should be available to the application + +through Real_Time.Clock. See D.8(49). + +105/2 + +106/2 + +107/2 + +108/2 + +109/2 + +110/2 + +111/2 + +112/2 + +• On a multiprocessor system, each processor should have a separate and disjoint ready queue. See + +112.1/3 + +D.13(9). + +• When appropriate, implementations should provide configuration mechanisms to change the + +value of Execution_Time.CPU_Tick. See D.14(29/2). + +• For a timing event, the handler should be executed directly by the real-time clock interrupt + +mechanism. See D.15(25). + +• Each dispatching domain should have separate and disjoint ready queues. See D.16.1(31). +• The PCS should allow for multiple tasks to call the RPC-receiver. See E.5(28). +• The System.RPC.Write operation should raise Storage_Error if it runs out of space when writing + +an item. See E.5(29). + +• If COBOL (respectively, C) is supported in the target environment, then interfacing to COBOL + +(respectively, C) should be supported as specified in Annex B. See F(7/3). + +• Packed decimal should be used as the internal representation for objects of subtype S when + +S'Machine_Radix = 10. See F.1(2). + +• If Fortran (respectively, C) is supported in the target environment, then interfacing to Fortran + +(respectively, C) should be supported as specified in Annex B. See G(7/3). + +• Mixed real and complex operations (as well as pure-imaginary and complex operations) should +not be performed by converting the real (resp. pure-imaginary) operand to complex. See +G.1.1(56). + +• If Real'Signed_Zeros is True for Numerics.Generic_Complex_Types, a rational treatment of the + +signs of zero results and result components should be provided. See G.1.1(58). + +• If Complex_Types.Real'Signed_Zeros is True for Numerics.Generic_Complex_Elementary_- +Functions, a rational treatment of the signs of zero results and result components should be +provided. See G.1.2(49). + +• For elementary functions, the forward trigonometric functions without a Cycle parameter should +not be implemented by calling the corresponding version with a Cycle parameter. Log without a +Base parameter should not be implemented by calling Log with a Base parameter. See +G.2.4(19). + +113/2 + +114/2 + +114.1/3 + +115/2 + +116/2 + +117/2 + +118/2 + +119/2 + +120/2 + +121/3 + +122/3 + +123/2 + +801 13 December 2012 + +Implementation Advice M.3 + + Ada Reference Manual — 2012 Edition + +124/2 + +125/2 + +• For complex arithmetic, the Compose_From_Polar function without a Cycle parameter should +not be implemented by calling Compose_From_Polar with a Cycle parameter. See G.2.6(15). +• Solve and Inverse for Numerics.Generic_Real_Arrays should be implemented using established +techniques such as LU decomposition and the result should be refined by an iteration on the +residuals. See G.3.1(88/3). + +126/2 + +• The equality operator should be used to test that a matrix in Numerics.Generic_Real_Arrays is + +symmetric. See G.3.1(90/2). + +126.1/3 + +127/2 + +• An implementation should minimize the circumstances under which the algorithm used for +Numerics.Generic_Real_Arrays.Eigenvalues and Numerics.Generic_Real_Arrays.Eigensystem +fails to converge. See G.3.1(91/3). + +• Solve and Inverse for Numerics.Generic_Complex_Arrays should be implemented using +established techniques and the result should be refined by an iteration on the residuals. See +G.3.2(158/3). + +128/2 + +• The equality and negation operators should be used to test that a matrix is Hermitian. See + +G.3.2(160/2). + +128.1/3 + +• An implementation should minimize the circumstances under which the algorithm used for +and + +Numerics.Generic_Complex_Arrays.Eigenvalues +Numerics.Generic_Complex_Arrays.Eigensystem fails to converge. See G.3.2(160.1/3). + +129/2 + +• Mixed real and complex operations should not be performed by converting the real operand to + +complex. See G.3.2(161/2). + +130/2 + +• The information produced by pragma Reviewable should be provided in both a human-readable + +and machine-readable form, and the latter form should be documented. See H.3.1(19). + +131/2 + +• Object code listings should be provided both in a symbolic format and in a numeric format. See + +H.3.1(20). + +132/3 + +• If the partition elaboration policy is Sequential and the Environment task becomes permanently +blocked during elaboration, then the partition should be immediately terminated. See H.6(15/3). + +M.3 Implementation Advice + +13 December 2012 802 + + Ada Reference Manual — 2012 Edition + +Annex N +(informative) +Glossary + +This Annex contains informal descriptions of some of the terms used in this International Standard. The +index provides references to more formal definitions of all of the terms used in this International Standard. + +1/2 + +Abstract type. An abstract type is a tagged type intended for use as an ancestor of other types, but which +is not allowed to have objects of its own. + +1.1/2 + +Access type. An access type has values that designate aliased objects. Access types correspond to “pointer +types” or “reference types” in some other languages. + +Aliased. An aliased view of an object is one that can be designated by an access value. Objects allocated +by allocators are aliased. Objects can also be explicitly declared as aliased with the reserved word aliased. +The Access attribute can be used to create an access value designating an aliased object. + +2 + +3 + +Ancestor. An ancestor of a type is the type itself or, in the case of a type derived from other types, its +parent type or one of its progenitor types or one of their ancestors. Note that ancestor and descendant are +inverse relationships. + +3.1/2 + +Array type. An array type is a composite type whose components are all of the same type. Components +are selected by indexing. + +4 + +Aspect. An aspect is a specifiable property of an entity. An aspect may be specified by an +aspect_specification on the declaration of the entity. Some aspects may be queried via attributes. + +Assertion. An assertion is a boolean expression that appears in any of the following: a pragma Assert, a +predicate, a precondition, a postcondition, an invariant, a constraint, or a null exclusion. An assertion is +expected to be True at run time at certain specified places. + +4.1/3 + +4.2/3 + +Category (of types). A category of types is a set of types with one or more common properties, such as +primitive operations. A category of types that is closed under derivation is also known as a class. + +4.3/2 + +Character type. A character type is an enumeration type whose values include characters. + +Class (of types). A class is a set of types that is closed under derivation, which means that if a given type +is in the class, then all types derived from that type are also in the class. The set of types of a class share +common properties, such as their primitive operations. + +Compilation unit. The text of a program can be submitted to the compiler in one or more compilations. +Each compilation is a succession of compilation_units. A compilation_unit contains either the declaration, +the body, or a renaming of a program unit. + +Composite type. A composite type may have components. + +Construct. A construct is a piece of text (explicit or implicit) that is an instance of a syntactic category +defined under “Syntax”. + +5 + +6/2 + +7 + +8/2 + +9 + +Container. A container is an object that contain other objects all of the same type, which could be class- +wide. Several predefined container types are provided by the children of package Ada.Containers (see +A.18.1). + +9.1/3 + +803 13 December 2012 + +Glossary Annex N + + Ada Reference Manual — 2012 Edition + +10 + +11 + +Controlled type. A controlled type supports user-defined assignment and finalization. Objects are always +finalized before being destroyed. + +Declaration. A declaration is a language construct that associates a name with (a view of) an entity. A +declaration may appear explicitly in the program text (an explicit declaration), or may be supposed to +occur at a given place in the text as a consequence of the semantics of another construct (an implicit +declaration). + +12/2 + +This paragraph was deleted. + +13/2 + +Derived type. A derived type is a type defined in terms of one or more other types given in a derived type +definition. The first of those types is the parent type of the derived type and any others are progenitor +types. Each class containing the parent type or a progenitor type also contains the derived type. The +derived type inherits properties such as components and primitive operations from the parent and +progenitors. A type together with the types derived from it (directly or indirectly) form a derivation class. + +13.1/2 + +Descendant. A type is a descendant of itself, its parent and progenitor types, and their ancestors. Note that +descendant and ancestor are inverse relationships. + +14 + +15/2 + +Discrete type. A discrete type is either an integer type or an enumeration type. Discrete types may be +used, for example, in case_statements and as array indices. + +Discriminant. A discriminant is a parameter for a composite type. It can control, for example, the bounds +of a component of the type if the component is an array. A discriminant for a task type can be used to pass +data to a task of the type upon creation. + +15.1/2 + +Elaboration. The process by which a declaration achieves its run-time effect is called elaboration. +Elaboration is one of the forms of execution. + +16 + +17 + +Elementary type. An elementary type does not have components. + +Enumeration type. An enumeration type is defined by an enumeration of its values, which may be named +by identifiers or character literals. + +17.1/2 + +Evaluation. The process by which an expression achieves its run-time effect is called evaluation. +Evaluation is one of the forms of execution. + +18 + +Exception. An exception represents a kind of exceptional situation; an occurrence of such a situation (at +run time) is called an exception occurrence. To raise an exception is to abandon normal program +execution so as to draw attention to the fact that the corresponding situation has arisen. Performing some +actions in response to the arising of an exception is called handling the exception. + +19 + +Execution. The process by which a construct achieves its run-time effect is called execution. Execution of +a declaration is also called elaboration. Execution of an expression is also called evaluation. + +19.1/2 + +Function. A function is a form of subprogram that returns a result and can be called as part of an +expression. + +20 + +Generic unit. A generic unit is a template for a (nongeneric) program unit; the template can be +parameterized by objects, types, subprograms, and packages. An instance of a generic unit is created by a +generic_instantiation. The rules of the language are enforced when a generic unit is compiled, using a +generic contract model; additional checks are performed upon instantiation to verify the contract is met. +That is, the declaration of a generic unit represents a contract between the body of the generic and +instances of the generic. Generic units can be used to perform the role that macros sometimes play in other +languages. + +Annex N Glossary + +13 December 2012 804 + + Ada Reference Manual — 2012 Edition + +Incomplete type. An incomplete type gives a view of a type that reveals only some of its properties. The +remaining properties are provided by the full view given elsewhere. Incomplete types can be used for +defining recursive data structures. + +20.1/2 + +Indexable container type. An indexable container type is one that has user-defined behavior for indexing, +via the Constant_Indexing or Variable_Indexing aspects. + +20.2/3 + +Integer type. Integer types comprise the signed integer types and the modular types. A signed integer type +has a base range that includes both positive and negative numbers, and has operations that may raise an +exception when the result is outside the base range. A modular type has a base range whose lower bound is +zero, and has operations with “wraparound” semantics. Modular types subsume what are called “unsigned +types” in some other languages. + +21 + +Interface type. An interface type is a form of abstract tagged type which has no components or concrete +operations except possibly null procedures. Interface types are used for composing other interfaces and +tagged types and thereby provide multiple inheritance. Only an interface type can be used as a progenitor +of another type. + +21.1/2 + +Invariant. A invariant is an assertion that is expected to be True for all objects of a given private type +when viewed from outside the defining package. + +21.2/3 + +Iterable container type. An iterable container type is one that has user-defined behavior for iteration, via +the Default_Iterator and Iterator_Element aspects. + +21.3/3 + +Iterator. An iterator is a construct that is used to loop over the elements of an array or container. Iterators +may be user defined, and may perform arbitrary computations to access elements from a container. + +21.4/3 + +Library unit. A library unit is a separately compiled program unit, and is always a package, subprogram, +or generic unit. Library units may have other (logically nested) library units as children, and may have +other program units physically nested within them. A root library unit, together with its children and +grandchildren and so on, form a subsystem. + +Limited type. A limited type is a type for which copying (such as in an assignment_statement) is not +allowed. A nonlimited type is a type for which copying is allowed. + +Object. An object is either a constant or a variable. An object contains a value. An object is created by an +object_declaration or by an allocator. A formal parameter is (a view of) an object. A subcomponent of an +object is an object. + +22 + +23/2 + +24 + +Overriding operation. An overriding operation is one that replaces an inherited primitive operation. +Operations may be marked explicitly as overriding or not overriding. + +24.1/2 + +Package. Packages are program units that allow the specification of groups of logically related entities. +Typically, a package contains the declaration of a type (often a private type or private extension) along +with the declarations of primitive subprograms of the type, which can be called from outside the package, +while their inner workings remain hidden from outside users. + +25 + +Parent. The parent of a derived type is the first type given in the definition of the derived type. The parent +can be almost any kind of type, including an interface type. + +25.1/2 + +Partition. A partition is a part of a program. Each partition consists of a set of library units. Each partition +may run in a separate address space, possibly on a separate computer. A program may contain just one +partition. A distributed program typically contains multiple partitions, which can execute concurrently. + +26 + +805 13 December 2012 + +Glossary Annex N + + Ada Reference Manual — 2012 Edition + +26.1/3 + +Postcondition. A postcondition is an assertion that is expected to be True when a given subprogram +returns normally. + +27 + +Pragma. A pragma is a compiler directive. There are language-defined pragmas that give instructions for +optimization, listing control, etc. An implementation may support additional (implementation-defined) +pragmas. + +27.1/3 + +Precondition. A precondition is an assertion that is expected to be True when a given subprogram is +called. + +27.2/3 + +Predicate. A predicate is an assertion that is expected to be True for all objects of a given subtype. + +28 + +29/2 + +30/2 + +Primitive operations. The primitive operations of a type are the operations (such as subprograms) +declared together with the type declaration. They are inherited by other types in the same class of types. +For a tagged type, the primitive subprograms are dispatching subprograms, providing run-time +polymorphism. A dispatching subprogram may be called with statically tagged operands, in which case the +subprogram body invoked is determined at compile time. Alternatively, a dispatching subprogram may be +called using a dispatching call, in which case the subprogram body invoked is determined at run time. + +Private extension. A private extension is a type that extends another type, with the additional properties +hidden from its clients. + +Private type. A private type gives a view of a type that reveals only some of its properties. The remaining +properties are provided by the full view given elsewhere. Private types can be used for defining +abstractions that hide unnecessary details from their clients. + +30.1/2 + +Procedure. A procedure is a form of subprogram that does not return a result and can only be called by a +statement. + +30.2/2 + +Progenitor. A progenitor of a derived type is one of the types given in the definition of the derived type +other than the first. A progenitor is always an interface type. Interfaces, tasks, and protected types may +also have progenitors. + +31 + +32 + +Program. A program is a set of partitions, each of which may execute in a separate address space, +possibly on a separate computer. A partition consists of a set of library units. + +Program unit. A program unit is either a package, a task unit, a protected unit, a protected entry, a +generic unit, or an explicitly declared subprogram other than an enumeration literal. Certain kinds of +program units can be separately compiled. Alternatively, they can appear physically nested within other +program units. + +33/2 + +Protected type. A protected type is a composite type whose components are accessible only through one +of its protected operations which synchronize concurrent access by multiple tasks. + +34 + +35 + +36 + +Real type. A real type has values that are approximations of the real numbers. Floating point and fixed +point types are real types. + +Record extension. A record extension is a type that extends another type by adding additional +components. + +Record type. A record type is a composite type consisting of zero or more named components, possibly of +different types. + +36.1/3 + +Reference type. A reference type is one that has user-defined behavior for “.all”, defined by the +Implicit_Dereference aspect. + +Annex N Glossary + +13 December 2012 806 + + Ada Reference Manual — 2012 Edition + +Renaming. A renaming_declaration is a declaration that does not define a new entity, but instead defines +a view of an existing entity. + +36.2/2 + +Scalar type. A scalar type is either a discrete type or a real type. + +Storage pool. Each access-to-object type has an associated storage pool object. The storage for an object +created by an allocator comes from the storage pool of the type of the allocator. Some storage pools may +be partitioned into subpools in order to support finer-grained storage management. + +37 + +37.1/3 + +Stream. A stream is a sequence of elements that can be used, along with the stream-oriented attributes, to +support marshalling and unmarshalling of values of most types. + +37.2/3 + +Subprogram. A subprogram is a section of a program that can be executed in various contexts. It is +invoked by a subprogram call that may qualify the effect of the subprogram through the passing of +parameters. There are two forms of subprograms: functions, which return values, and procedures, which +do not. + +37.3/2 + +Subtype. A subtype is a type together with optional constraints, null exclusions, and predicates, which +constrain the values of the subtype to satisfy certain conditions. The values of a subtype are a subset of the +values of its type. + +38/3 + +Synchronized. A synchronized entity is one that will work safely with multiple tasks at one time. A +synchronized interface can be an ancestor of a task or a protected type. Such a task or protected type is +called a synchronized tagged type. + +38.1/2 + +Tagged type. The objects of a tagged type have a run-time type tag, which indicates the specific type with +which the object was originally created. An operand of a class-wide tagged type can be used in a +dispatching call; the tag indicates which subprogram body to invoke. Nondispatching calls, in which the +subprogram body to invoke is determined at compile time, are also allowed. Tagged types may be +extended with additional components. + +Task type. A task type is a composite type used to represent active entities which execute concurrently +and which can communicate via queued task entries. The top-level task of a partition is called the +environment task. + +Type. Each object has a type. A type has an associated set of values, and a set of primitive operations +which implement the fundamental aspects of its semantics. Types are grouped into categories. Most +language-defined categories of types are also classes of types. + +39 + +40/2 + +41/2 + +View. A view of an entity reveals some or all of the properties of the entity. A single entity may have +multiple views. + +42/2 + +807 13 December 2012 + +Glossary Annex N + + Ada Reference Manual — 2012 Edition + +Annex P +(informative) +Syntax Summary + +This Annex summarizes the complete syntax of the language. See 1.1.4 for a description of the notation +used. + +2.3: +identifier ::= + identifier_start {identifier_start | identifier_extend} + +2.3: +identifier_start ::= + letter_uppercase + | letter_lowercase + | letter_titlecase + | letter_modifier + | letter_other + | number_letter + +2.3: +identifier_extend ::= + mark_non_spacing + | mark_spacing_combining + | number_decimal + | punctuation_connector + +2.4: +numeric_literal ::= decimal_literal | based_literal + +2.4.1: +decimal_literal ::= numeral [.numeral] [exponent] + +2.4.1: +numeral ::= digit {[underline] digit} + +2.4.1: +exponent ::= E [+] numeral | E – numeral + +2.4.1: +digit ::= 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 + +2.4.2: +based_literal ::= + base # based_numeral [.based_numeral] # [exponent] + +2.4.2: +base ::= numeral + +2.4.2: +based_numeral ::= + extended_digit {[underline] extended_digit} + +2.4.2: +extended_digit ::= digit | A | B | C | D | E | F + +2.5: +character_literal ::= 'graphic_character' + +2.6: +string_literal ::= "{string_element}" + +2.6: +string_element ::= "" | non_quotation_mark_graphic_character + +809 13 December 2012 + +Syntax Summary Annex P + + Ada Reference Manual — 2012 Edition + +2.7: +comment ::= --{non_end_of_line_character} + +2.8: +pragma ::= + pragma identifier [(pragma_argument_association {, pragma_argument_association})]; + +2.8: +pragma_argument_association ::= + [pragma_argument_identifier =>] name + | [pragma_argument_identifier =>] expression + | pragma_argument_aspect_mark => name + | pragma_argument_aspect_mark => expression + +3.1: +basic_declaration ::= + type_declaration + | object_declaration + | subprogram_declaration + | null_procedure_declaration + | package_declaration + | exception_declaration + | generic_instantiation + +3.1: +defining_identifier ::= identifier + +| subtype_declaration +| number_declaration +| abstract_subprogram_declaration +| expression_function_declaration +| renaming_declaration +| generic_declaration + +3.2.1: +type_declaration ::= full_type_declaration + | incomplete_type_declaration + | private_type_declaration + | private_extension_declaration + +3.2.1: +full_type_declaration ::= + type defining_identifier [known_discriminant_part] is type_definition + [aspect_specification]; + | task_type_declaration + | protected_type_declaration + +3.2.1: +type_definition ::= + enumeration_type_definition + | real_type_definition + | record_type_definition + | derived_type_definition + +| integer_type_definition +| array_type_definition +| access_type_definition +| interface_type_definition + +3.2.2: +subtype_declaration ::= + subtype defining_identifier is subtype_indication + [aspect_specification]; + +3.2.2: +subtype_indication ::= [null_exclusion] subtype_mark [constraint] + +3.2.2: +subtype_mark ::= subtype_name + +3.2.2: +constraint ::= scalar_constraint | composite_constraint + +3.2.2: +scalar_constraint ::= + range_constraint | digits_constraint | delta_constraint + +3.2.2: + +Annex P Syntax Summary + +13 December 2012 810 + + Ada Reference Manual — 2012 Edition + +composite_constraint ::= + index_constraint | discriminant_constraint + +3.3.1: +object_declaration ::= + defining_identifier_list : [aliased] [constant] subtype_indication [:= expression] + [aspect_specification]; + | defining_identifier_list : [aliased] [constant] access_definition [:= expression] + [aspect_specification]; + | defining_identifier_list : [aliased] [constant] array_type_definition [:= expression] + [aspect_specification]; + | single_task_declaration + | single_protected_declaration + +3.3.1: +defining_identifier_list ::= + defining_identifier {, defining_identifier} + +3.3.2: +number_declaration ::= + defining_identifier_list : constant := static_expression; + +3.4: +derived_type_definition ::= + [abstract] [limited] new parent_subtype_indication [[and interface_list] record_extension_part] + +3.5: +range_constraint ::= range range + +3.5: +range ::= range_attribute_reference + | simple_expression .. simple_expression + +3.5.1: +enumeration_type_definition ::= + (enumeration_literal_specification {, enumeration_literal_specification}) + +3.5.1: +enumeration_literal_specification ::= defining_identifier | defining_character_literal + +3.5.1: +defining_character_literal ::= character_literal + +3.5.4: +integer_type_definition ::= signed_integer_type_definition | modular_type_definition + +3.5.4: +signed_integer_type_definition ::= range static_simple_expression .. static_simple_expression + +3.5.4: +modular_type_definition ::= mod static_expression + +3.5.6: +real_type_definition ::= + floating_point_definition | fixed_point_definition + +3.5.7: +floating_point_definition ::= + digits static_expression [real_range_specification] + +3.5.7: +real_range_specification ::= + range static_simple_expression .. static_simple_expression + +3.5.9: +fixed_point_definition ::= ordinary_fixed_point_definition | decimal_fixed_point_definition + +3.5.9: + +811 13 December 2012 + +Syntax Summary Annex P + + Ada Reference Manual — 2012 Edition + +ordinary_fixed_point_definition ::= + delta static_expression real_range_specification + +3.5.9: +decimal_fixed_point_definition ::= + delta static_expression digits static_expression [real_range_specification] + +3.5.9: +digits_constraint ::= + digits static_expression [range_constraint] + +3.6: +array_type_definition ::= + unconstrained_array_definition | constrained_array_definition + +3.6: +unconstrained_array_definition ::= + array(index_subtype_definition {, index_subtype_definition}) of component_definition + +3.6: +index_subtype_definition ::= subtype_mark range <> + +3.6: +constrained_array_definition ::= + array (discrete_subtype_definition {, discrete_subtype_definition}) of component_definition + +3.6: +discrete_subtype_definition ::= discrete_subtype_indication | range + +3.6: +component_definition ::= + [aliased] subtype_indication + | [aliased] access_definition + +3.6.1: +index_constraint ::= (discrete_range {, discrete_range}) + +3.6.1: +discrete_range ::= discrete_subtype_indication | range + +3.7: +discriminant_part ::= unknown_discriminant_part | known_discriminant_part + +3.7: +unknown_discriminant_part ::= (<>) + +3.7: +known_discriminant_part ::= + (discriminant_specification {; discriminant_specification}) + +3.7: +discriminant_specification ::= + defining_identifier_list : [null_exclusion] subtype_mark [:= default_expression] + | defining_identifier_list : access_definition [:= default_expression] + +3.7: +default_expression ::= expression + +3.7.1: +discriminant_constraint ::= + (discriminant_association {, discriminant_association}) + +3.7.1: +discriminant_association ::= + [discriminant_selector_name {| discriminant_selector_name} =>] expression + +3.8: +record_type_definition ::= [[abstract] tagged] [limited] record_definition + +Annex P Syntax Summary + +13 December 2012 812 + + Ada Reference Manual — 2012 Edition + +3.8: +record_definition ::= + record + component_list + end record + | null record + +3.8: +component_list ::= + component_item {component_item} + | {component_item} variant_part + | null; + +3.8: +component_item ::= component_declaration | aspect_clause + +3.8: +component_declaration ::= + defining_identifier_list : component_definition [:= default_expression] + [aspect_specification]; + +3.8.1: +variant_part ::= + case discriminant_direct_name is + variant + {variant} + end case; + +3.8.1: +variant ::= + when discrete_choice_list => + component_list + +3.8.1: +discrete_choice_list ::= discrete_choice {| discrete_choice} + +3.8.1: +discrete_choice ::= choice_expression | discrete_subtype_indication | range | others + +3.9.1: +record_extension_part ::= with record_definition + +3.9.3: +abstract_subprogram_declaration ::= + [overriding_indicator] + subprogram_specification is abstract + [aspect_specification]; + +3.9.4: +interface_type_definition ::= + [limited | task | protected | synchronized] interface [and interface_list] + +3.9.4: +interface_list ::= interface_subtype_mark {and interface_subtype_mark} + +3.10: +access_type_definition ::= + [null_exclusion] access_to_object_definition + | [null_exclusion] access_to_subprogram_definition + +3.10: +access_to_object_definition ::= + access [general_access_modifier] subtype_indication + +3.10: +general_access_modifier ::= all | constant + +813 13 December 2012 + +Syntax Summary Annex P + + Ada Reference Manual — 2012 Edition + +3.10: +access_to_subprogram_definition ::= + access [protected] procedure parameter_profile + | access [protected] function parameter_and_result_profile + +3.10: +null_exclusion ::= not null + +3.10: +access_definition ::= + [null_exclusion] access [constant] subtype_mark + | [null_exclusion] access [protected] procedure parameter_profile + | [null_exclusion] access [protected] function parameter_and_result_profile + +3.10.1: +incomplete_type_declaration ::= type defining_identifier [discriminant_part] [is tagged]; + +3.11: +declarative_part ::= {declarative_item} + +3.11: +declarative_item ::= + basic_declarative_item | body + +3.11: +basic_declarative_item ::= + basic_declaration | aspect_clause | use_clause + +3.11: +body ::= proper_body | body_stub + +3.11: +proper_body ::= + subprogram_body | package_body | task_body | protected_body + +4.1: +name ::= +| explicit_dereference + direct_name +| slice + | indexed_component +| attribute_reference + | selected_component +| function_call + | type_conversion +| qualified_expression + | character_literal + | generalized_reference | generalized_indexing + +4.1: +direct_name ::= identifier | operator_symbol + +4.1: +prefix ::= name | implicit_dereference + +4.1: +explicit_dereference ::= name.all + +4.1: +implicit_dereference ::= name + +4.1.1: +indexed_component ::= prefix(expression {, expression}) + +4.1.2: +slice ::= prefix(discrete_range) + +4.1.3: +selected_component ::= prefix . selector_name + +4.1.3: +selector_name ::= identifier | character_literal | operator_symbol + +4.1.4: + +Annex P Syntax Summary + +13 December 2012 814 + + Ada Reference Manual — 2012 Edition + +attribute_reference ::= prefix'attribute_designator + +4.1.4: +attribute_designator ::= + identifier[(static_expression)] + | Access | Delta | Digits | Mod + +4.1.4: +range_attribute_reference ::= prefix'range_attribute_designator + +4.1.4: +range_attribute_designator ::= Range[(static_expression)] + +4.1.5: +generalized_reference ::= reference_object_name + +4.1.6: +generalized_indexing ::= indexable_container_object_prefix actual_parameter_part + +4.3: +aggregate ::= record_aggregate | extension_aggregate | array_aggregate + +4.3.1: +record_aggregate ::= (record_component_association_list) + +4.3.1: +record_component_association_list ::= + record_component_association {, record_component_association} + | null record + +4.3.1: +record_component_association ::= + [component_choice_list =>] expression + | component_choice_list => <> + +4.3.1: +component_choice_list ::= + component_selector_name {| component_selector_name} + | others + +4.3.2: +extension_aggregate ::= + (ancestor_part with record_component_association_list) + +4.3.2: +ancestor_part ::= expression | subtype_mark + +4.3.3: +array_aggregate ::= + positional_array_aggregate | named_array_aggregate + +4.3.3: +positional_array_aggregate ::= + (expression, expression {, expression}) + | (expression {, expression}, others => expression) + | (expression {, expression}, others => <>) + +4.3.3: +named_array_aggregate ::= + (array_component_association {, array_component_association}) + +4.3.3: +array_component_association ::= + discrete_choice_list => expression + | discrete_choice_list => <> + +4.4: +expression ::= + +815 13 December 2012 + +Syntax Summary Annex P + + Ada Reference Manual — 2012 Edition + + relation {and relation} + | relation {or relation} + | relation {xor relation} + +| relation {and then relation} +| relation {or else relation} + +4.4: +choice_expression ::= + choice_relation {and choice_relation} + | choice_relation {or choice_relation} + | choice_relation {xor choice_relation} + | choice_relation {and then choice_relation} + | choice_relation {or else choice_relation} + +4.4: +choice_relation ::= + simple_expression [relational_operator simple_expression] + +4.4: +relation ::= + simple_expression [relational_operator simple_expression] + | simple_expression [not] in membership_choice_list + +4.4: +membership_choice_list ::= membership_choice {| membership_choice} + +4.4: +membership_choice ::= choice_expression | range | subtype_mark + +4.4: +simple_expression ::= [unary_adding_operator] term {binary_adding_operator term} + +4.4: +term ::= factor {multiplying_operator factor} + +4.4: +factor ::= primary [** primary] | abs primary | not primary + +4.4: +primary ::= + numeric_literal | null | string_literal | aggregate + | name | allocator | (expression) + | (conditional_expression) | (quantified_expression) + +4.5: +logical_operator ::= + +4.5: +relational_operator ::= + +4.5: +binary_adding_operator ::= + +4.5: +unary_adding_operator ::= + +4.5: +multiplying_operator ::= + + and | or | xor + + = | /= | < | <= | > | >= + + + | – | & + + + | – + + * | / | mod | rem + +4.5: +highest_precedence_operator ::= + + ** | abs | not + +4.5.7: +conditional_expression ::= if_expression | case_expression + +4.5.7: +if_expression ::= + if condition then dependent_expression + {elsif condition then dependent_expression} + [else dependent_expression] + +Annex P Syntax Summary + +13 December 2012 816 + + Ada Reference Manual — 2012 Edition + +4.5.7: +condition ::= boolean_expression + +4.5.7: +case_expression ::= + case selecting_expression is + case_expression_alternative {, + case_expression_alternative} + +4.5.7: +case_expression_alternative ::= + when discrete_choice_list => + dependent_expression + +4.5.8: +quantified_expression ::= for quantifier loop_parameter_specification => predicate + | for quantifier iterator_specification => predicate + +4.5.8: +quantifier ::= all | some + +4.5.8: +predicate ::= boolean_expression + +4.6: +type_conversion ::= + subtype_mark(expression) + | subtype_mark(name) + +4.7: +qualified_expression ::= + subtype_mark'(expression) | subtype_mark'aggregate + +4.8: +allocator ::= + new [subpool_specification] subtype_indication + | new [subpool_specification] qualified_expression + +4.8: +subpool_specification ::= (subpool_handle_name) + +5.1: +sequence_of_statements ::= statement {statement} {label} + +5.1: +statement ::= + {label} simple_statement | {label} compound_statement + +5.1: +simple_statement ::= null_statement + | assignment_statement + | goto_statement + | simple_return_statement + | requeue_statement + | abort_statement + | code_statement + +5.1: +compound_statement ::= + if_statement + | loop_statement + | extended_return_statement + | accept_statement + +5.1: +null_statement ::= null; + +| exit_statement +| procedure_call_statement +| entry_call_statement +| delay_statement +| raise_statement + +| case_statement +| block_statement + +| select_statement + +817 13 December 2012 + +Syntax Summary Annex P + + Ada Reference Manual — 2012 Edition + +5.1: +label ::= <> + +5.1: +statement_identifier ::= direct_name + +5.2: +assignment_statement ::= + variable_name := expression; + +5.3: +if_statement ::= + if condition then + sequence_of_statements + {elsif condition then + sequence_of_statements} + [else + sequence_of_statements] + end if; + +5.4: +case_statement ::= + case selecting_expression is + case_statement_alternative + {case_statement_alternative} + end case; + +5.4: +case_statement_alternative ::= + when discrete_choice_list => + sequence_of_statements + +5.5: +loop_statement ::= + [loop_statement_identifier:] + [iteration_scheme] loop + sequence_of_statements + end loop [loop_identifier]; + +5.5: +iteration_scheme ::= while condition + | for loop_parameter_specification + | for iterator_specification + +5.5: +loop_parameter_specification ::= + defining_identifier in [reverse] discrete_subtype_definition + +5.5.2: +iterator_specification ::= + defining_identifier in [reverse] iterator_name + | defining_identifier [: subtype_indication] of [reverse] iterable_name + +5.6: +block_statement ::= + [block_statement_identifier:] + [declare + declarative_part] + begin + handled_sequence_of_statements + end [block_identifier]; + +5.7: +exit_statement ::= + exit [loop_name] [when condition]; + +Annex P Syntax Summary + +13 December 2012 818 + + Ada Reference Manual — 2012 Edition + +5.8: +goto_statement ::= goto label_name; + +6.1: +subprogram_declaration ::= + [overriding_indicator] + subprogram_specification + [aspect_specification]; + +6.1: +subprogram_specification ::= + procedure_specification + | function_specification + +6.1: +procedure_specification ::= procedure defining_program_unit_name parameter_profile + +6.1: +function_specification ::= function defining_designator parameter_and_result_profile + +6.1: +designator ::= [parent_unit_name . ]identifier | operator_symbol + +6.1: +defining_designator ::= defining_program_unit_name | defining_operator_symbol + +6.1: +defining_program_unit_name ::= [parent_unit_name . ]defining_identifier + +6.1: +operator_symbol ::= string_literal + +6.1: +defining_operator_symbol ::= operator_symbol + +6.1: +parameter_profile ::= [formal_part] + +6.1: +parameter_and_result_profile ::= + [formal_part] return [null_exclusion] subtype_mark + | [formal_part] return access_definition + +6.1: +formal_part ::= + (parameter_specification {; parameter_specification}) + +6.1: +parameter_specification ::= + defining_identifier_list : [aliased] mode [null_exclusion] subtype_mark [:= default_expression] + | defining_identifier_list : access_definition [:= default_expression] + +6.1: +mode ::= [in] | in out | out + +6.3: +subprogram_body ::= + [overriding_indicator] + subprogram_specification + [aspect_specification] is + declarative_part + begin + handled_sequence_of_statements + end [designator]; + +6.4: +procedure_call_statement ::= + procedure_name; + +819 13 December 2012 + +Syntax Summary Annex P + + Ada Reference Manual — 2012 Edition + + | procedure_prefix actual_parameter_part; + +6.4: +function_call ::= + function_name + | function_prefix actual_parameter_part + +6.4: +actual_parameter_part ::= + (parameter_association {, parameter_association}) + +6.4: +parameter_association ::= + [formal_parameter_selector_name =>] explicit_actual_parameter + +6.4: +explicit_actual_parameter ::= expression | variable_name + +6.5: +simple_return_statement ::= return [expression]; + +6.5: +extended_return_object_declaration ::= + defining_identifier : [aliased][constant] return_subtype_indication [:= expression] + +6.5: +extended_return_statement ::= + return extended_return_object_declaration [do + handled_sequence_of_statements + end return]; + +6.5: +return_subtype_indication ::= subtype_indication | access_definition + +6.7: +null_procedure_declaration ::= + [overriding_indicator] + procedure_specification is null + [aspect_specification]; + +6.8: +expression_function_declaration ::= + [overriding_indicator] + function_specification is + (expression) + [aspect_specification]; + +7.1: +package_declaration ::= package_specification; + +7.1: +package_specification ::= + package defining_program_unit_name + [aspect_specification] is + {basic_declarative_item} + [private + {basic_declarative_item}] + end [[parent_unit_name.]identifier] + +7.2: +package_body ::= + package body defining_program_unit_name + [aspect_specification] is + declarative_part + [begin + handled_sequence_of_statements] + +Annex P Syntax Summary + +13 December 2012 820 + + Ada Reference Manual — 2012 Edition + + end [[parent_unit_name.]identifier]; + +7.3: +private_type_declaration ::= + type defining_identifier [discriminant_part] is [[abstract] tagged] [limited] private + [aspect_specification]; + +7.3: +private_extension_declaration ::= + type defining_identifier [discriminant_part] is + [abstract] [limited | synchronized] new ancestor_subtype_indication + [and interface_list] with private + [aspect_specification]; + +8.3.1: +overriding_indicator ::= [not] overriding + +8.4: +use_clause ::= use_package_clause | use_type_clause + +8.4: +use_package_clause ::= use package_name {, package_name}; + +8.4: +use_type_clause ::= use [all] type subtype_mark {, subtype_mark}; + +8.5: +renaming_declaration ::= + object_renaming_declaration + | exception_renaming_declaration + | package_renaming_declaration + | subprogram_renaming_declaration + | generic_renaming_declaration + +8.5.1: +object_renaming_declaration ::= + defining_identifier : [null_exclusion] subtype_mark renames object_name + [aspect_specification]; + | defining_identifier : access_definition renames object_name + [aspect_specification]; + +8.5.2: +exception_renaming_declaration ::= defining_identifier : exception renames exception_name + [aspect_specification]; + +8.5.3: +package_renaming_declaration ::= package defining_program_unit_name renames package_name + [aspect_specification]; + +8.5.4: +subprogram_renaming_declaration ::= + [overriding_indicator] + subprogram_specification renames callable_entity_name + [aspect_specification]; + +8.5.5: +generic_renaming_declaration ::= + generic package + [aspect_specification]; + | generic procedure + [aspect_specification]; + | generic function + [aspect_specification]; + +defining_program_unit_name renames generic_package_name + +defining_program_unit_name renames generic_procedure_name + +defining_program_unit_name renames generic_function_name + +9.1: +task_type_declaration ::= + +821 13 December 2012 + +Syntax Summary Annex P + + Ada Reference Manual — 2012 Edition + + task type defining_identifier [known_discriminant_part] + [aspect_specification] [is + [new interface_list with] + task_definition]; + +9.1: +single_task_declaration ::= + task defining_identifier + [aspect_specification][is + [new interface_list with] + task_definition]; + +9.1: +task_definition ::= + {task_item} + [ private + {task_item}] + end [task_identifier] + +9.1: +task_item ::= entry_declaration | aspect_clause + +9.1: +task_body ::= + task body defining_identifier + [aspect_specification] is + declarative_part + begin + handled_sequence_of_statements + end [task_identifier]; + +9.4: +protected_type_declaration ::= + protected type defining_identifier [known_discriminant_part] + [aspect_specification] is + [new interface_list with] + protected_definition; + +9.4: +single_protected_declaration ::= + protected defining_identifier + [aspect_specification] is + [new interface_list with] + protected_definition; + +9.4: +protected_definition ::= + { protected_operation_declaration } +[ private + { protected_element_declaration } ] + end [protected_identifier] + +9.4: +protected_operation_declaration ::= subprogram_declaration + | entry_declaration + | aspect_clause + +9.4: +protected_element_declaration ::= protected_operation_declaration + | component_declaration + +9.4: +protected_body ::= + protected body defining_identifier + [aspect_specification] is + +Annex P Syntax Summary + +13 December 2012 822 + + Ada Reference Manual — 2012 Edition + + { protected_operation_item } + end [protected_identifier]; + +9.4: +protected_operation_item ::= subprogram_declaration + | subprogram_body + | entry_body + | aspect_clause + +9.5: +synchronization_kind ::= By_Entry | By_Protected_Procedure | Optional + +9.5.2: +entry_declaration ::= + [overriding_indicator] + entry defining_identifier [(discrete_subtype_definition)] parameter_profile + [aspect_specification]; + +9.5.2: +accept_statement ::= + accept entry_direct_name [(entry_index)] parameter_profile [do + handled_sequence_of_statements + end [entry_identifier]]; + +9.5.2: +entry_index ::= expression + +9.5.2: +entry_body ::= + entry defining_identifier entry_body_formal_part entry_barrier is + declarative_part + begin + handled_sequence_of_statements + end [entry_identifier]; + +9.5.2: +entry_body_formal_part ::= [(entry_index_specification)] parameter_profile + +9.5.2: +entry_barrier ::= when condition + +9.5.2: +entry_index_specification ::= for defining_identifier in discrete_subtype_definition + +9.5.3: +entry_call_statement ::= entry_name [actual_parameter_part]; + +9.5.4: +requeue_statement ::= requeue procedure_or_entry_name [with abort]; + +9.6: +delay_statement ::= delay_until_statement | delay_relative_statement + +9.6: +delay_until_statement ::= delay until delay_expression; + +9.6: +delay_relative_statement ::= delay delay_expression; + +9.7: +select_statement ::= + selective_accept + | timed_entry_call + | conditional_entry_call + | asynchronous_select + +9.7.1: +selective_accept ::= + +823 13 December 2012 + +Syntax Summary Annex P + + Ada Reference Manual — 2012 Edition + + select + [guard] + select_alternative +{ or + [guard] + select_alternative } +[ else + sequence_of_statements ] + end select; + +9.7.1: +guard ::= when condition => + +9.7.1: +select_alternative ::= + accept_alternative + | delay_alternative + | terminate_alternative + +9.7.1: +accept_alternative ::= + accept_statement [sequence_of_statements] + +9.7.1: +delay_alternative ::= + delay_statement [sequence_of_statements] + +9.7.1: +terminate_alternative ::= terminate; + +9.7.2: +timed_entry_call ::= + select + entry_call_alternative + or + delay_alternative + end select; + +9.7.2: +entry_call_alternative ::= + procedure_or_entry_call [sequence_of_statements] + +9.7.2: +procedure_or_entry_call ::= + procedure_call_statement | entry_call_statement + +9.7.3: +conditional_entry_call ::= + select + entry_call_alternative + else + sequence_of_statements + end select; + +9.7.4: +asynchronous_select ::= + select + triggering_alternative + then abort + abortable_part + end select; + +9.7.4: +triggering_alternative ::= triggering_statement [sequence_of_statements] + +9.7.4: + +Annex P Syntax Summary + +13 December 2012 824 + + Ada Reference Manual — 2012 Edition + +triggering_statement ::= procedure_or_entry_call | delay_statement + +9.7.4: +abortable_part ::= sequence_of_statements + +9.8: +abort_statement ::= abort task_name {, task_name}; + +10.1.1: +compilation ::= {compilation_unit} + +10.1.1: +compilation_unit ::= + context_clause library_item + | context_clause subunit + +10.1.1: +library_item ::= [private] library_unit_declaration + | library_unit_body + | [private] library_unit_renaming_declaration + +10.1.1: +library_unit_declaration ::= + subprogram_declaration + | generic_declaration + +| package_declaration +| generic_instantiation + +10.1.1: +library_unit_renaming_declaration ::= + package_renaming_declaration + | generic_renaming_declaration + | subprogram_renaming_declaration + +10.1.1: +library_unit_body ::= subprogram_body | package_body + +10.1.1: +parent_unit_name ::= name + +10.1.2: +context_clause ::= {context_item} + +10.1.2: +context_item ::= with_clause | use_clause + +10.1.2: +with_clause ::= limited_with_clause | nonlimited_with_clause + +10.1.2: +limited_with_clause ::= limited [private] with library_unit_name {, library_unit_name}; + +10.1.2: +nonlimited_with_clause ::= [private] with library_unit_name {, library_unit_name}; + +10.1.3: +body_stub ::= subprogram_body_stub | package_body_stub | task_body_stub | protected_body_stub + +10.1.3: +subprogram_body_stub ::= + [overriding_indicator] + subprogram_specification is separate + [aspect_specification]; + +10.1.3: +package_body_stub ::= + package body defining_identifier is separate + [aspect_specification]; + +10.1.3: +task_body_stub ::= + +825 13 December 2012 + +Syntax Summary Annex P + + Ada Reference Manual — 2012 Edition + + task body defining_identifier is separate + [aspect_specification]; + +10.1.3: +protected_body_stub ::= + protected body defining_identifier is separate + [aspect_specification]; + +10.1.3: +subunit ::= separate (parent_unit_name) proper_body + +11.1: +exception_declaration ::= defining_identifier_list : exception + [aspect_specification]; + +11.2: +handled_sequence_of_statements ::= + sequence_of_statements + [exception + exception_handler + {exception_handler}] + +11.2: +exception_handler ::= + when [choice_parameter_specification:] exception_choice {| exception_choice} => + sequence_of_statements + +11.2: +choice_parameter_specification ::= defining_identifier + +11.2: +exception_choice ::= exception_name | others + +11.3: +raise_statement ::= raise; + | raise exception_name [with string_expression]; + +12.1: +generic_declaration ::= generic_subprogram_declaration | generic_package_declaration + +12.1: +generic_subprogram_declaration ::= + generic_formal_part subprogram_specification + [aspect_specification]; + +12.1: +generic_package_declaration ::= + generic_formal_part package_specification; + +12.1: +generic_formal_part ::= generic {generic_formal_parameter_declaration | use_clause} + +12.1: +generic_formal_parameter_declaration ::= + formal_object_declaration + | formal_type_declaration + | formal_subprogram_declaration + | formal_package_declaration + +12.3: +generic_instantiation ::= + package defining_program_unit_name is + new generic_package_name [generic_actual_part] + [aspect_specification]; + | [overriding_indicator] + procedure defining_program_unit_name is + new generic_procedure_name [generic_actual_part] + +Annex P Syntax Summary + +13 December 2012 826 + + Ada Reference Manual — 2012 Edition + + [aspect_specification]; + | [overriding_indicator] + function defining_designator is + new generic_function_name [generic_actual_part] + [aspect_specification]; + +12.3: +generic_actual_part ::= + (generic_association {, generic_association}) + +12.3: +generic_association ::= + [generic_formal_parameter_selector_name =>] explicit_generic_actual_parameter + +12.3: +explicit_generic_actual_parameter ::= expression | variable_name + | subprogram_name | entry_name | subtype_mark + | package_instance_name + +12.4: +formal_object_declaration ::= + defining_identifier_list : mode [null_exclusion] subtype_mark [:= default_expression] + [aspect_specification]; + | defining_identifier_list : mode access_definition [:= default_expression] + [aspect_specification]; + +12.5: +formal_type_declaration ::= + formal_complete_type_declaration + | formal_incomplete_type_declaration + +12.5: +formal_complete_type_declaration ::= + type defining_identifier[discriminant_part] is formal_type_definition + [aspect_specification]; + +12.5: +formal_incomplete_type_declaration ::= + type defining_identifier[discriminant_part] [is tagged]; + +12.5: +formal_type_definition ::= + formal_private_type_definition + | formal_derived_type_definition + | formal_discrete_type_definition + | formal_signed_integer_type_definition + | formal_modular_type_definition + | formal_floating_point_definition + | formal_ordinary_fixed_point_definition + | formal_decimal_fixed_point_definition + | formal_array_type_definition + | formal_access_type_definition + | formal_interface_type_definition + +12.5.1: +formal_private_type_definition ::= [[abstract] tagged] [limited] private + +12.5.1: +formal_derived_type_definition ::= + [abstract] [limited | synchronized] new subtype_mark [[and interface_list]with private] + +12.5.2: +formal_discrete_type_definition ::= (<>) + +12.5.2: +formal_signed_integer_type_definition ::= range <> + +827 13 December 2012 + +Syntax Summary Annex P + + Ada Reference Manual — 2012 Edition + +12.5.2: +formal_modular_type_definition ::= mod <> + +12.5.2: +formal_floating_point_definition ::= digits <> + +12.5.2: +formal_ordinary_fixed_point_definition ::= delta <> + +12.5.2: +formal_decimal_fixed_point_definition ::= delta <> digits <> + +12.5.3: +formal_array_type_definition ::= array_type_definition + +12.5.4: +formal_access_type_definition ::= access_type_definition + +12.5.5: +formal_interface_type_definition ::= interface_type_definition + +12.6: +formal_subprogram_declaration ::= formal_concrete_subprogram_declaration + | formal_abstract_subprogram_declaration + +12.6: +formal_concrete_subprogram_declaration ::= + with subprogram_specification [is subprogram_default] + [aspect_specification]; + +12.6: +formal_abstract_subprogram_declaration ::= + with subprogram_specification is abstract [subprogram_default] + [aspect_specification]; + +12.6: +subprogram_default ::= default_name | <> | null + +12.6: +default_name ::= name + +12.7: +formal_package_declaration ::= + with package defining_identifier is new generic_package_name formal_package_actual_part + [aspect_specification]; + +12.7: +formal_package_actual_part ::= + ([others =>] <>) + | [generic_actual_part] + | (formal_package_association {, formal_package_association} [, others => <>]) + +12.7: +formal_package_association ::= + generic_association + | generic_formal_parameter_selector_name => <> + +13.1: +aspect_clause ::= attribute_definition_clause + | enumeration_representation_clause + | record_representation_clause + | at_clause + +13.1: +local_name ::= direct_name + | direct_name'attribute_designator + | library_unit_name + +Annex P Syntax Summary + +13 December 2012 828 + + Ada Reference Manual — 2012 Edition + +13.1.1: +aspect_specification ::= + with aspect_mark [=> aspect_definition] {, + aspect_mark [=> aspect_definition] } + +13.1.1: +aspect_mark ::= aspect_identifier['Class] + +13.1.1: +aspect_definition ::= name | expression | identifier + +13.3: +attribute_definition_clause ::= + for local_name'attribute_designator use expression; + | for local_name'attribute_designator use name; + +13.4: +enumeration_representation_clause ::= + for first_subtype_local_name use enumeration_aggregate; + +13.4: +enumeration_aggregate ::= array_aggregate + +13.5.1: +record_representation_clause ::= + for first_subtype_local_name use + record [mod_clause] + {component_clause} + end record; + +13.5.1: +component_clause ::= + component_local_name at position range first_bit .. last_bit; + +13.5.1: +position ::= static_expression + +13.5.1: +first_bit ::= static_simple_expression + +13.5.1: +last_bit ::= static_simple_expression + +13.8: +code_statement ::= qualified_expression; + +13.11.3: +storage_pool_indicator ::= storage_pool_name | null + +13.12: +restriction ::= restriction_identifier + | restriction_parameter_identifier => restriction_parameter_argument + +13.12: +restriction_parameter_argument ::= name | expression + +J.3: +delta_constraint ::= delta static_expression [range_constraint] + +J.7: +at_clause ::= for direct_name use at expression; + +J.8: +mod_clause ::= at mod static_expression; + +829 13 December 2012 + +Syntax Summary Annex P + + Ada Reference Manual — 2012 Edition + +Syntax Cross Reference + +1/3 + +In the following syntax cross reference, each syntactic category is followed by the subclause number +where it is defined. In addition, each syntactic category S is followed by a list of the categories that use S +in their definitions. For example, the first listing below shows that abort_statement appears in the +definition of simple_statement. + +abort_statement + +simple_statement + +abortable_part + +asynchronous_select + +abstract_subprogram_declaration + +basic_declaration + +accept_alternative + +select_alternative + +accept_statement + +accept_alternative +compound_statement + +access_definition + +component_definition +discriminant_specification +formal_object_declaration +object_declaration +object_renaming_declaration +parameter_and_result_profile +parameter_specification +return_subtype_indication + +access_to_object_definition +access_type_definition + +access_to_subprogram_definition +access_type_definition + +access_type_definition + +formal_access_type_definition +type_definition + +actual_parameter_part + +entry_call_statement +function_call +generalized_indexing +procedure_call_statement + +aggregate + +primary +qualified_expression + +allocator + +primary + +ancestor_part + +extension_aggregate + +9.8 +5.1 + +9.7.4 +9.7.4 + +3.9.3 +3.1 + +9.7.1 +9.7.1 + +9.5.2 +9.7.1 +5.1 + +3.10 +3.6 +3.7 +12.4 +3.3.1 +8.5.1 +6.1 +6.1 +6.5 + +3.10 +3.10 + +3.10 +3.10 + +3.10 +12.5.4 +3.2.1 + +6.4 +9.5.3 +6.4 +4.1.6 +6.4 + +4.3 +4.4 +4.7 + +4.8 +4.4 + +4.3.2 +4.3.2 + +array_aggregate + +aggregate +enumeration_aggregate + +array_component_association +named_array_aggregate + +array_type_definition + +formal_array_type_definition +object_declaration +type_definition + +aspect_clause + +basic_declarative_item +component_item +protected_operation_declaration +protected_operation_item +task_item + +aspect_definition + +aspect_specification + +aspect_mark + +aspect_specification +pragma_argument_association + +aspect_specification + +abstract_subprogram_declaration +component_declaration +entry_declaration +exception_declaration +exception_renaming_declaration +expression_function_declaration +formal_abstract_subprogram_declaration +formal_complete_type_declaration +formal_concrete_subprogram_declaration +formal_object_declaration +formal_package_declaration +full_type_declaration +generic_instantiation +generic_renaming_declaration +generic_subprogram_declaration +null_procedure_declaration +object_declaration +object_renaming_declaration +package_body +package_body_stub +package_renaming_declaration +package_specification +private_extension_declaration + +4.3.3 +4.3 +13.4 + +4.3.3 +4.3.3 + +3.6 +12.5.3 +3.3.1 +3.2.1 + +13.1 +3.11 +3.8 +9.4 +9.4 +9.1 + +13.1.1 +13.1.1 + +13.1.1 +13.1.1 +2.8 + +13.1.1 +3.9.3 +3.8 +9.5.2 +11.1 +8.5.2 +6.8 + +12.5 + +12.4 +12.7 +3.2.1 +12.3 +8.5.5 +12.1 +6.7 +3.3.1 +8.5.1 +7.2 +10.1.3 +8.5.3 +7.1 +7.3 + +12.6 + +12.6 + +Annex P Syntax Summary + +13 December 2012 830 + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + private_type_declaration +protected_body +protected_body_stub +protected_type_declaration +single_protected_declaration +single_task_declaration +subprogram_body +subprogram_body_stub +subprogram_declaration +subprogram_renaming_declaration +subtype_declaration +task_body +task_body_stub +task_type_declaration + +assignment_statement +simple_statement + +asynchronous_select +select_statement + +at_clause + +aspect_clause + +attribute_definition_clause +aspect_clause + +attribute_designator + +attribute_definition_clause +attribute_reference +local_name + +attribute_reference + +name + +base + +based_literal + +based_literal + +numeric_literal + +based_numeral + +based_literal + +basic_declaration + +basic_declarative_item + +basic_declarative_item + +declarative_item +package_specification + +binary_adding_operator +simple_expression + +block_statement + +compound_statement + +body + +declarative_item + +body_stub +body + +7.3 +9.4 +10.1.3 +9.4 +9.4 +9.1 +6.3 +10.1.3 +6.1 +8.5.4 +3.2.2 +9.1 +10.1.3 +9.1 + +5.2 +5.1 + +9.7.4 +9.7 + +J.7 +13.1 + +13.3 +13.1 + +4.1.4 +13.3 +4.1.4 +13.1 + +4.1.4 +4.1 + +2.4.2 +2.4.2 + +2.4.2 +2.4 + +2.4.2 +2.4.2 + +3.1 +3.11 + +3.11 +3.11 +7.1 + +4.5 +4.4 + +5.6 +5.1 + +3.11 +3.11 + +10.1.3 +3.11 + +Ada Reference Manual — 2012 Edition + +case_expression + +conditional_expression + +case_expression_alternative +case_expression + +case_statement + +compound_statement + +case_statement_alternative +case_statement + +character + +comment + +character_literal + +defining_character_literal +name +selector_name + +choice_expression + +discrete_choice +membership_choice + +choice_parameter_specification + +exception_handler + +choice_relation + +choice_expression + +code_statement + +simple_statement + +compilation_unit +compilation + +component_choice_list + +record_component_association + +component_clause + +record_representation_clause + +component_declaration + +component_item +protected_element_declaration + +component_definition + +component_declaration +constrained_array_definition +unconstrained_array_definition + +component_item + +component_list + +component_list + +record_definition +variant + +composite_constraint +constraint + +compound_statement +statement + +4.5.7 +4.5.7 + +4.5.7 +4.5.7 + +5.4 +5.1 + +5.4 +5.4 + +2.1 +2.7 + +2.5 +3.5.1 +4.1 +4.1.3 + +4.4 +3.8.1 +4.4 + +11.2 +11.2 + +4.4 +4.4 + +13.8 +5.1 + +10.1.1 +10.1.1 + +4.3.1 +4.3.1 + +13.5.1 +13.5.1 + +3.8 +3.8 +9.4 + +3.6 +3.8 +3.6 +3.6 + +3.8 +3.8 + +3.8 +3.8 +3.8.1 + +3.2.2 +3.2.2 + +5.1 +5.1 + +831 13 December 2012 + +Syntax Summary Annex P + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + Ada Reference Manual — 2012 Edition + +condition + +entry_barrier +exit_statement +guard +if_expression +if_statement +iteration_scheme + +conditional_entry_call +select_statement + +conditional_expression + +primary + +constrained_array_definition +array_type_definition + +constraint + +subtype_indication + +context_clause + +compilation_unit + +context_item + +context_clause + +decimal_fixed_point_definition +fixed_point_definition + +decimal_literal + +numeric_literal + +declarative_item + +declarative_part + +declarative_part + +block_statement +entry_body +package_body +subprogram_body +task_body + +default_expression + +component_declaration +discriminant_specification +formal_object_declaration +parameter_specification + +default_name + +subprogram_default + +defining_character_literal + +enumeration_literal_specification + +defining_designator + +function_specification +generic_instantiation + +defining_identifier + +choice_parameter_specification +defining_identifier_list +defining_program_unit_name +entry_body + +4.5.7 +9.5.2 +5.7 +9.7.1 +4.5.7 +5.3 +5.5 + +9.7.3 +9.7 + +4.5.7 +4.4 + +3.6 +3.6 + +3.2.2 +3.2.2 + +10.1.2 +10.1.1 + +10.1.2 +10.1.2 + +3.5.9 +3.5.9 + +2.4.1 +2.4 + +3.11 +3.11 + +3.11 +5.6 +9.5.2 +7.2 +6.3 +9.1 + +3.7 +3.8 +3.7 +12.4 +6.1 + +12.6 +12.6 + +3.5.1 +3.5.1 + +6.1 +6.1 +12.3 + +3.1 +11.2 +3.3.1 +6.1 +9.5.2 + +entry_declaration +entry_index_specification +enumeration_literal_specification +exception_renaming_declaration +extended_return_object_declaration +formal_complete_type_declaration +formal_incomplete_type_declaration +formal_package_declaration +full_type_declaration +incomplete_type_declaration +iterator_specification +loop_parameter_specification +object_renaming_declaration +package_body_stub +private_extension_declaration +private_type_declaration +protected_body +protected_body_stub +protected_type_declaration +single_protected_declaration +single_task_declaration +subtype_declaration +task_body +task_body_stub +task_type_declaration + +defining_identifier_list + +component_declaration +discriminant_specification +exception_declaration +formal_object_declaration +number_declaration +object_declaration +parameter_specification + +defining_operator_symbol + +defining_designator + +defining_program_unit_name +defining_designator +generic_instantiation +generic_renaming_declaration +package_body +package_renaming_declaration +package_specification +procedure_specification + +delay_alternative + +select_alternative +timed_entry_call + +delay_relative_statement +delay_statement + +delay_statement + +delay_alternative +simple_statement +triggering_statement + +delay_until_statement +delay_statement + +9.5.2 +9.5.2 +3.5.1 +8.5.2 +6.5 +12.5 +12.5 +12.7 +3.2.1 +3.10.1 +5.5.2 +5.5 +8.5.1 +10.1.3 +7.3 +7.3 +9.4 +10.1.3 +9.4 +9.4 +9.1 +3.2.2 +9.1 +10.1.3 +9.1 + +3.3.1 +3.8 +3.7 +11.1 +12.4 +3.3.2 +3.3.1 +6.1 + +6.1 +6.1 + +6.1 +6.1 +12.3 +8.5.5 +7.2 +8.5.3 +7.1 +6.1 + +9.7.1 +9.7.1 +9.7.2 + +9.6 +9.6 + +9.6 +9.7.1 +5.1 +9.7.4 + +9.6 +9.6 + +Annex P Syntax Summary + +13 December 2012 832 + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + delta_constraint + +scalar_constraint + +derived_type_definition +type_definition + +designator + +subprogram_body + +digit 2.4.1 + +extended_digit +numeral + +digits_constraint + +scalar_constraint + +direct_name + +accept_statement +at_clause +local_name +name +statement_identifier +variant_part + +discrete_choice + +discrete_choice_list + +discrete_choice_list + +array_component_association +case_expression_alternative +case_statement_alternative +variant + +discrete_range + +index_constraint +slice + +discrete_subtype_definition + +constrained_array_definition +entry_declaration +entry_index_specification +loop_parameter_specification + +discriminant_association + +discriminant_constraint + +discriminant_constraint + +composite_constraint + +discriminant_part + +formal_complete_type_declaration +formal_incomplete_type_declaration +incomplete_type_declaration +private_extension_declaration +private_type_declaration + +discriminant_specification + +known_discriminant_part + +entry_barrier + +entry_body + +entry_body + +J.3 +3.2.2 + +3.4 +3.2.1 + +6.1 +6.3 + +2.4.2 +2.4.1 + +3.5.9 +3.2.2 + +4.1 +9.5.2 +J.7 +13.1 +4.1 +5.1 +3.8.1 + +3.8.1 +3.8.1 + +3.8.1 +4.3.3 +4.5.7 +5.4 +3.8.1 + +3.6.1 +3.6.1 +4.1.2 + +3.6 +3.6 +9.5.2 +9.5.2 +5.5 + +3.7.1 +3.7.1 + +3.7.1 +3.2.2 + +3.7 +12.5 +12.5 +3.10.1 +7.3 +7.3 + +3.7 +3.7 + +9.5.2 +9.5.2 + +9.5.2 + +Ada Reference Manual — 2012 Edition + +protected_operation_item + +entry_body_formal_part + +entry_body + +entry_call_alternative + +conditional_entry_call +timed_entry_call + +entry_call_statement + +procedure_or_entry_call +simple_statement + +entry_declaration + +protected_operation_declaration +task_item + +entry_index + +accept_statement + +entry_index_specification + +entry_body_formal_part + +enumeration_aggregate + +enumeration_representation_clause + +enumeration_literal_specification +enumeration_type_definition + +enumeration_representation_clause + +aspect_clause + +enumeration_type_definition + +type_definition + +exception_choice + +exception_handler + +exception_declaration +basic_declaration + +exception_handler + +handled_sequence_of_statements + +exception_renaming_declaration +renaming_declaration + +exit_statement + +simple_statement + +explicit_actual_parameter + +parameter_association + +explicit_dereference + +name + +explicit_generic_actual_parameter + +generic_association + +exponent + +based_literal +decimal_literal + +expression + +9.4 + +9.5.2 +9.5.2 + +9.7.2 +9.7.3 +9.7.2 + +9.5.3 +9.7.2 +5.1 + +9.5.2 +9.4 +9.1 + +9.5.2 +9.5.2 + +9.5.2 +9.5.2 + +13.4 +13.4 + +3.5.1 +3.5.1 + +13.4 +13.1 + +3.5.1 +3.2.1 + +11.2 +11.2 + +11.1 +3.1 + +11.2 +11.2 + +8.5.2 +8.5 + +5.7 +5.1 + +6.4 +6.4 + +4.1 +4.1 + +12.3 +12.3 + +2.4.1 +2.4.2 +2.4.1 + +4.4 + +833 13 December 2012 + +Syntax Summary Annex P + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + Ada Reference Manual — 2012 Edition + +ancestor_part +array_component_association +aspect_definition +assignment_statement +at_clause +attribute_definition_clause +attribute_designator +case_expression +case_expression_alternative +case_statement +condition +decimal_fixed_point_definition +default_expression +delay_relative_statement +delay_until_statement +delta_constraint +digits_constraint +discriminant_association +entry_index +explicit_actual_parameter +explicit_generic_actual_parameter +expression_function_declaration +extended_return_object_declaration +floating_point_definition +if_expression +indexed_component +mod_clause +modular_type_definition +number_declaration +object_declaration +ordinary_fixed_point_definition +position +positional_array_aggregate +pragma_argument_association +predicate +primary +qualified_expression +raise_statement +range_attribute_designator +record_component_association +restriction_parameter_argument +simple_return_statement +type_conversion + +expression_function_declaration + +basic_declaration + +extended_digit + +based_numeral + +extended_return_object_declaration +extended_return_statement + +extended_return_statement +compound_statement + +extension_aggregate +aggregate + +factor + +term + +4.3.2 +4.3.3 +13.1.1 +5.2 +J.7 +13.3 +4.1.4 +4.5.7 +4.5.7 +5.4 +4.5.7 +3.5.9 +3.7 +9.6 +9.6 +J.3 +3.5.9 +3.7.1 +9.5.2 +6.4 +12.3 +6.8 +6.5 +3.5.7 +4.5.7 +4.1.1 +J.8 +3.5.4 +3.3.2 +3.3.1 +3.5.9 +13.5.1 +4.3.3 +2.8 +4.5.8 +4.4 +4.7 +11.3 +4.1.4 +4.3.1 +13.12 +6.5 +4.6 + +6.8 +3.1 + +2.4.2 +2.4.2 + +6.5 +6.5 + +6.5 +5.1 + +4.3.2 +4.3 + +4.4 +4.4 + +first_bit + +component_clause + +fixed_point_definition + +real_type_definition + +floating_point_definition +real_type_definition + +formal_abstract_subprogram_declaration +formal_subprogram_declaration + +formal_access_type_definition +formal_type_definition + +formal_array_type_definition + +formal_type_definition + +formal_complete_type_declaration +formal_type_declaration + +formal_concrete_subprogram_declaration +formal_subprogram_declaration + +formal_decimal_fixed_point_definition + +formal_type_definition + +formal_derived_type_definition +formal_type_definition + +formal_discrete_type_definition +formal_type_definition + +formal_floating_point_definition +formal_type_definition + +formal_incomplete_type_declaration + +formal_type_declaration + +formal_interface_type_definition +formal_type_definition + +formal_modular_type_definition +formal_type_definition + +13.5.1 +13.5.1 + +3.5.9 +3.5.6 + +3.5.7 +3.5.6 + +12.6 +12.6 + +12.5.4 +12.5 + +12.5.3 +12.5 + +12.5 +12.5 + +12.6 +12.6 + +12.5.2 +12.5 + +12.5.1 +12.5 + +12.5.2 +12.5 + +12.5.2 +12.5 + +12.5 +12.5 + +12.5.5 +12.5 + +12.5.2 +12.5 + +formal_object_declaration + +12.4 +generic_formal_parameter_declaration 12.1 + +formal_ordinary_fixed_point_definition + +formal_type_definition + +formal_package_actual_part + +formal_package_declaration + +formal_package_association + +formal_package_actual_part + +12.5.2 +12.5 + +12.7 +12.7 + +12.7 +12.7 + +formal_package_declaration + +12.7 +generic_formal_parameter_declaration 12.1 + +formal_part + +parameter_and_result_profile +parameter_profile + +6.1 +6.1 +6.1 + +formal_private_type_definition + +12.5.1 + +Annex P Syntax Summary + +13 December 2012 834 + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + formal_type_definition + +formal_signed_integer_type_definition + +formal_type_definition + +12.5 + +12.5.2 +12.5 + +formal_subprogram_declaration + +12.6 +generic_formal_parameter_declaration 12.1 + +formal_type_declaration + +12.5 +generic_formal_parameter_declaration 12.1 + +formal_type_definition + +formal_complete_type_declaration + +full_type_declaration +type_declaration + +function_call + +name + +function_specification + +expression_function_declaration +subprogram_specification + +general_access_modifier + +access_to_object_definition + +generalized_indexing + +name + +generalized_reference + +name + +generic_actual_part + +formal_package_actual_part +generic_instantiation + +generic_association + +formal_package_association +generic_actual_part + +generic_declaration + +basic_declaration +library_unit_declaration + +generic_formal_parameter_declaration + +generic_formal_part + +generic_formal_part + +generic_package_declaration +generic_subprogram_declaration + +generic_instantiation + +basic_declaration +library_unit_declaration + +generic_package_declaration +generic_declaration + +generic_renaming_declaration + +library_unit_renaming_declaration +renaming_declaration + +generic_subprogram_declaration + +12.5 +12.5 + +3.2.1 +3.2.1 + +6.4 +4.1 + +6.1 +6.8 +6.1 + +3.10 +3.10 + +4.1.6 +4.1 + +4.1.5 +4.1 + +12.3 +12.7 +12.3 + +12.3 +12.7 +12.3 + +12.1 +3.1 +10.1.1 + +12.1 +12.1 + +12.1 +12.1 +12.1 + +12.3 +3.1 +10.1.1 + +12.1 +12.1 + +8.5.5 +10.1.1 +8.5 + +12.1 + +Ada Reference Manual — 2012 Edition + +generic_declaration + +goto_statement + +simple_statement + +graphic_character + +character_literal +string_element + +guard + +selective_accept + +handled_sequence_of_statements + +accept_statement +block_statement +entry_body +extended_return_statement +package_body +subprogram_body +task_body + +identifier + +accept_statement +aspect_definition +aspect_mark +attribute_designator +block_statement +defining_identifier +designator +direct_name +entry_body +loop_statement +package_body +package_specification +pragma +pragma_argument_association +protected_body +protected_definition +restriction +selector_name +task_body +task_definition + +identifier_extend +identifier + +identifier_start +identifier + +if_expression + +conditional_expression + +if_statement + +compound_statement + +implicit_dereference + +prefix + +incomplete_type_declaration + +type_declaration + +index_constraint + +12.1 + +5.8 +5.1 + +2.1 +2.5 +2.6 + +9.7.1 +9.7.1 + +11.2 +9.5.2 +5.6 +9.5.2 +6.5 +7.2 +6.3 +9.1 + +2.3 +9.5.2 +13.1.1 +13.1.1 +4.1.4 +5.6 +3.1 +6.1 +4.1 +9.5.2 +5.5 +7.2 +7.1 +2.8 +2.8 +9.4 +9.4 +13.12 +4.1.3 +9.1 +9.1 + +2.3 +2.3 + +2.3 +2.3 + +4.5.7 +4.5.7 + +5.3 +5.1 + +4.1 +4.1 + +3.10.1 +3.2.1 + +3.6.1 + +835 13 December 2012 + +Syntax Summary Annex P + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + Ada Reference Manual — 2012 Edition + +composite_constraint + +index_subtype_definition + +unconstrained_array_definition + +indexed_component + +name + +integer_type_definition +type_definition + +interface_list + +derived_type_definition +formal_derived_type_definition +interface_type_definition +private_extension_declaration +protected_type_declaration +single_protected_declaration +single_task_declaration +task_type_declaration + +interface_type_definition + +formal_interface_type_definition +type_definition + +iteration_scheme + +loop_statement + +iterator_specification + +iteration_scheme +quantified_expression + +known_discriminant_part +discriminant_part +full_type_declaration +protected_type_declaration +task_type_declaration + +label 5.1 + +sequence_of_statements +statement + +last_bit + +component_clause + +letter_lowercase + +identifier_start + +letter_modifier + +identifier_start + +letter_other + +identifier_start + +letter_titlecase + +identifier_start + +letter_uppercase + +identifier_start + +library_item + +compilation_unit + +library_unit_body + +3.2.2 + +3.6 +3.6 + +4.1.1 +4.1 + +3.5.4 +3.2.1 + +3.9.4 +3.4 +12.5.1 +3.9.4 +7.3 +9.4 +9.4 +9.1 +9.1 + +3.9.4 +12.5.5 +3.2.1 + +5.5 +5.5 + +5.5.2 +5.5 +4.5.8 + +3.7 +3.7 +3.2.1 +9.4 +9.1 + +5.1 +5.1 + +13.5.1 +13.5.1 + +... +2.3 + +... +2.3 + +... +2.3 + +... +2.3 + +... +2.3 + +10.1.1 +10.1.1 + +10.1.1 + +library_item + +library_unit_declaration +library_item + +library_unit_renaming_declaration + +library_item + +limited_with_clause +with_clause + +local_name + +attribute_definition_clause +component_clause +enumeration_representation_clause +record_representation_clause + +loop_parameter_specification + +iteration_scheme +quantified_expression + +loop_statement + +compound_statement + +mark_non_spacing + +identifier_extend + +mark_spacing_combining +identifier_extend + +membership_choice + +membership_choice_list + +membership_choice_list + +relation + +mod_clause + +record_representation_clause + +mode + +formal_object_declaration +parameter_specification + +modular_type_definition + +integer_type_definition + +multiplying_operator + +term + +name + +abort_statement +aspect_definition +assignment_statement +attribute_definition_clause +default_name +entry_call_statement +exception_choice +exception_renaming_declaration +exit_statement +explicit_actual_parameter +explicit_dereference +explicit_generic_actual_parameter +formal_package_declaration + +10.1.1 + +10.1.1 +10.1.1 + +10.1.1 +10.1.1 + +10.1.2 +10.1.2 + +13.1 +13.3 +13.5.1 +13.4 +13.5.1 + +5.5 +5.5 +4.5.8 + +5.5 +5.1 + +... +2.3 + +... +2.3 + +4.4 +4.4 + +4.4 +4.4 + +J.8 +13.5.1 + +6.1 +12.4 +6.1 + +3.5.4 +3.5.4 + +4.5 +4.4 + +4.1 +9.8 +13.1.1 +5.2 +13.3 +12.6 +9.5.3 +11.2 +8.5.2 +5.7 +6.4 +4.1 +12.3 +12.7 + +Annex P Syntax Summary + +13 December 2012 836 + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + function_call +generalized_reference +generic_instantiation +generic_renaming_declaration +goto_statement +implicit_dereference +iterator_specification +limited_with_clause +local_name +nonlimited_with_clause +object_renaming_declaration +package_renaming_declaration +parent_unit_name +pragma_argument_association +prefix +primary +procedure_call_statement +raise_statement +requeue_statement +restriction_parameter_argument +storage_pool_indicator +subpool_specification +subprogram_renaming_declaration +subtype_mark +type_conversion +use_package_clause + +named_array_aggregate +array_aggregate + +nonlimited_with_clause +with_clause + +null_exclusion + +access_definition +access_type_definition +discriminant_specification +formal_object_declaration +object_renaming_declaration +parameter_and_result_profile +parameter_specification +subtype_indication + +null_procedure_declaration +basic_declaration + +null_statement + +simple_statement + +number_decimal + +identifier_extend + +number_declaration + +basic_declaration + +number_letter + +identifier_start + +numeral + +base +decimal_literal +exponent + +6.4 +4.1.5 +12.3 +8.5.5 +5.8 +4.1 +5.5.2 +10.1.2 +13.1 +10.1.2 +8.5.1 +8.5.3 +10.1.1 +2.8 +4.1 +4.4 +6.4 +11.3 +9.5.4 +13.12 +13.11.3 +4.8 +8.5.4 +3.2.2 +4.6 +8.4 + +4.3.3 +4.3.3 + +10.1.2 +10.1.2 + +3.10 +3.10 +3.10 +3.7 +12.4 +8.5.1 +6.1 +6.1 +3.2.2 + +6.7 +3.1 + +5.1 +5.1 + +... +2.3 + +3.3.2 +3.1 + +... +2.3 + +2.4.1 +2.4.2 +2.4.1 +2.4.1 + +Ada Reference Manual — 2012 Edition + +numeric_literal + +primary + +object_declaration + +basic_declaration + +object_renaming_declaration +renaming_declaration + +operator_symbol + +defining_operator_symbol +designator +direct_name +selector_name + +ordinary_fixed_point_definition +fixed_point_definition + +overriding_indicator + +abstract_subprogram_declaration +entry_declaration +expression_function_declaration +generic_instantiation +null_procedure_declaration +subprogram_body +subprogram_body_stub +subprogram_declaration +subprogram_renaming_declaration + +package_body + +library_unit_body +proper_body + +package_body_stub +body_stub + +package_declaration + +basic_declaration +library_unit_declaration + +package_renaming_declaration + +library_unit_renaming_declaration +renaming_declaration + +package_specification + +generic_package_declaration +package_declaration + +parameter_and_result_profile + +access_definition +access_to_subprogram_definition +function_specification + +parameter_association + +actual_parameter_part + +parameter_profile + +accept_statement +access_definition +access_to_subprogram_definition +entry_body_formal_part +entry_declaration +procedure_specification + +2.4 +4.4 + +3.3.1 +3.1 + +8.5.1 +8.5 + +6.1 +6.1 +6.1 +4.1 +4.1.3 + +3.5.9 +3.5.9 + +8.3.1 +3.9.3 +9.5.2 +6.8 +12.3 +6.7 +6.3 +10.1.3 +6.1 +8.5.4 + +7.2 +10.1.1 +3.11 + +10.1.3 +10.1.3 + +7.1 +3.1 +10.1.1 + +8.5.3 +10.1.1 +8.5 + +7.1 +12.1 +7.1 + +6.1 +3.10 +3.10 +6.1 + +6.4 +6.4 + +6.1 +9.5.2 +3.10 +3.10 +9.5.2 +9.5.2 +6.1 + +837 13 December 2012 + +Syntax Summary Annex P + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + Ada Reference Manual — 2012 Edition + +parameter_specification + +formal_part + +parent_unit_name + +defining_program_unit_name +designator +package_body +package_specification +subunit + +position + +component_clause + +positional_array_aggregate +array_aggregate + +pragma_argument_association + +pragma + +predicate + +quantified_expression + +prefix + +attribute_reference +function_call +generalized_indexing +indexed_component +procedure_call_statement +range_attribute_reference +selected_component +slice + +primary + +factor + +private_extension_declaration + +type_declaration + +private_type_declaration +type_declaration + +procedure_call_statement + +procedure_or_entry_call +simple_statement + +procedure_or_entry_call + +entry_call_alternative +triggering_statement + +procedure_specification + +null_procedure_declaration +subprogram_specification + +proper_body +body +subunit + +protected_body + +proper_body + +protected_body_stub +body_stub + +6.1 +6.1 + +10.1.1 +6.1 +6.1 +7.2 +7.1 +10.1.3 + +13.5.1 +13.5.1 + +4.3.3 +4.3.3 + +2.8 +2.8 + +4.5.8 +4.5.8 + +4.1 +4.1.4 +6.4 +4.1.6 +4.1.1 +6.4 +4.1.4 +4.1.3 +4.1.2 + +4.4 +4.4 + +7.3 +3.2.1 + +7.3 +3.2.1 + +6.4 +9.7.2 +5.1 + +9.7.2 +9.7.2 +9.7.4 + +6.1 +6.7 +6.1 + +3.11 +3.11 +10.1.3 + +9.4 +3.11 + +10.1.3 +10.1.3 + +protected_definition + +protected_type_declaration +single_protected_declaration + +protected_element_declaration +protected_definition + +protected_operation_declaration + +protected_definition +protected_element_declaration + +protected_operation_item +protected_body + +protected_type_declaration + +full_type_declaration + +punctuation_connector + +identifier_extend + +qualified_expression +allocator +code_statement +name + +quantified_expression + +primary + +quantifier + +quantified_expression + +raise_statement + +simple_statement + +range + +discrete_choice +discrete_range +discrete_subtype_definition +membership_choice +range_constraint + +range_attribute_designator + +range_attribute_reference + +range_attribute_reference + +range + +range_constraint + +delta_constraint +digits_constraint +scalar_constraint + +real_range_specification + +decimal_fixed_point_definition +floating_point_definition +ordinary_fixed_point_definition + +real_type_definition +type_definition + +record_aggregate +aggregate + +record_component_association + +9.4 +9.4 +9.4 + +9.4 +9.4 + +9.4 +9.4 +9.4 + +9.4 +9.4 + +9.4 +3.2.1 + +... +2.3 + +4.7 +4.8 +13.8 +4.1 + +4.5.8 +4.4 + +4.5.8 +4.5.8 + +11.3 +5.1 + +3.5 +3.8.1 +3.6.1 +3.6 +4.4 +3.5 + +4.1.4 +4.1.4 + +4.1.4 +3.5 + +3.5 +J.3 +3.5.9 +3.2.2 + +3.5.7 +3.5.9 +3.5.7 +3.5.9 + +3.5.6 +3.2.1 + +4.3.1 +4.3 + +4.3.1 + +Annex P Syntax Summary + +13 December 2012 838 + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + record_component_association_list + +4.3.1 + +record_component_association_list + +extension_aggregate +record_aggregate + +record_definition + +record_extension_part +record_type_definition + +record_extension_part + +derived_type_definition + +record_representation_clause + +aspect_clause + +record_type_definition +type_definition + +relation + +expression + +relational_operator +choice_relation +relation + +renaming_declaration +basic_declaration + +requeue_statement + +simple_statement + +restriction_parameter_argument + +restriction + +return_subtype_indication + +extended_return_object_declaration + +scalar_constraint +constraint + +select_alternative + +selective_accept + +select_statement + +compound_statement + +selected_component + +name + +selective_accept + +select_statement + +selector_name + +component_choice_list +discriminant_association +formal_package_association +generic_association +parameter_association +selected_component + +sequence_of_statements +abortable_part +accept_alternative + +4.3.1 +4.3.2 +4.3.1 + +3.8 +3.9.1 +3.8 + +3.9.1 +3.4 + +13.5.1 +13.1 + +3.8 +3.2.1 + +4.4 +4.4 + +4.5 +4.4 +4.4 + +8.5 +3.1 + +9.5.4 +5.1 + +13.12 +13.12 + +6.5 +6.5 + +3.2.2 +3.2.2 + +9.7.1 +9.7.1 + +9.7 +5.1 + +4.1.3 +4.1 + +9.7.1 +9.7 + +4.1.3 +4.3.1 +3.7.1 +12.7 +12.3 +6.4 +4.1.3 + +5.1 +9.7.4 +9.7.1 + +Ada Reference Manual — 2012 Edition + +case_statement_alternative +conditional_entry_call +delay_alternative +entry_call_alternative +exception_handler +handled_sequence_of_statements +if_statement +loop_statement +selective_accept +triggering_alternative + +signed_integer_type_definition +integer_type_definition + +simple_expression + +choice_relation +first_bit +last_bit +range +real_range_specification +relation +signed_integer_type_definition + +simple_return_statement + +simple_statement + +simple_statement +statement + +single_protected_declaration +object_declaration + +single_task_declaration +object_declaration + +slice 4.1.2 +name + +statement + +sequence_of_statements + +statement_identifier + +block_statement +label +loop_statement + +string_element + +string_literal + +string_literal + +operator_symbol +primary + +subpool_specification + +allocator + +subprogram_body + +library_unit_body +proper_body +protected_operation_item + +subprogram_body_stub + +body_stub + +5.4 +9.7.3 +9.7.1 +9.7.2 +11.2 +11.2 +5.3 +5.5 +9.7.1 +9.7.4 + +3.5.4 +3.5.4 + +4.4 +4.4 +13.5.1 +13.5.1 +3.5 +3.5.7 +4.4 +3.5.4 + +6.5 +5.1 + +5.1 +5.1 + +9.4 +3.3.1 + +9.1 +3.3.1 + +4.1 + +5.1 +5.1 + +5.1 +5.6 +5.1 +5.5 + +2.6 +2.6 + +2.6 +6.1 +4.4 + +4.8 +4.8 + +6.3 +10.1.1 +3.11 +9.4 + +10.1.3 +10.1.3 + +839 13 December 2012 + +Syntax Summary Annex P + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + Ada Reference Manual — 2012 Edition + +subprogram_declaration + +basic_declaration +library_unit_declaration +protected_operation_declaration +protected_operation_item + +subprogram_default + +6.1 +3.1 +10.1.1 +9.4 +9.4 + +12.6 + +formal_abstract_subprogram_declaration +formal_concrete_subprogram_declaration + +12.6 +12.6 + +subprogram_renaming_declaration + +library_unit_renaming_declaration +renaming_declaration + +8.5.4 +10.1.1 +8.5 + +subprogram_specification + +6.1 +3.9.3 + +abstract_subprogram_declaration +formal_abstract_subprogram_declaration +formal_concrete_subprogram_declaration +generic_subprogram_declaration +subprogram_body +subprogram_body_stub +subprogram_declaration +subprogram_renaming_declaration + +12.1 +6.3 +10.1.3 +6.1 +8.5.4 + +subtype_declaration + +basic_declaration + +subtype_indication + +access_to_object_definition +allocator +component_definition +derived_type_definition +discrete_choice +discrete_range +discrete_subtype_definition +iterator_specification +object_declaration +private_extension_declaration +return_subtype_indication +subtype_declaration + +subtype_mark + +access_definition +ancestor_part +discriminant_specification +explicit_generic_actual_parameter +formal_derived_type_definition +formal_object_declaration +index_subtype_definition +interface_list +membership_choice +object_renaming_declaration +parameter_and_result_profile +parameter_specification +qualified_expression +subtype_indication +type_conversion +use_type_clause + +subunit + +compilation_unit + +3.2.2 +3.1 + +3.2.2 +3.10 +4.8 +3.6 +3.4 +3.8.1 +3.6.1 +3.6 +5.5.2 +3.3.1 +7.3 +6.5 +3.2.2 + +3.2.2 +3.10 +4.3.2 +3.7 +12.3 +12.5.1 +12.4 +3.6 +3.9.4 +4.4 +8.5.1 +6.1 +6.1 +4.7 +3.2.2 +4.6 +8.4 + +10.1.3 +10.1.1 + +12.6 +12.6 + +term 4.4 + +simple_expression + +task_body + +proper_body + +task_body_stub +body_stub + +task_definition + +single_task_declaration +task_type_declaration + +task_item + +task_definition + +task_type_declaration + +full_type_declaration + +terminate_alternative + +select_alternative + +timed_entry_call + +select_statement + +triggering_alternative + +asynchronous_select + +triggering_statement + +triggering_alternative + +type_conversion +name + +type_declaration + +basic_declaration + +type_definition + +full_type_declaration + +unary_adding_operator +simple_expression + +unconstrained_array_definition +array_type_definition + +underline + +based_numeral +numeral + +unknown_discriminant_part +discriminant_part + +use_clause + +basic_declarative_item +context_item +generic_formal_part + +use_package_clause +use_clause + +use_type_clause +use_clause + +9.1 +3.11 + +10.1.3 +10.1.3 + +9.1 +9.1 +9.1 + +9.1 +9.1 + +9.1 +3.2.1 + +4.4 + +9.7.1 +9.7.1 + +9.7.2 +9.7 + +9.7.4 +9.7.4 + +9.7.4 +9.7.4 + +4.6 +4.1 + +3.2.1 +3.1 + +3.2.1 +3.2.1 + +4.5 +4.4 + +3.6 +3.6 + +... +2.4.2 +2.4.1 + +3.7 +3.7 + +8.4 +3.11 +10.1.2 +12.1 + +8.4 +8.4 + +8.4 +8.4 + +Annex P Syntax Summary + +13 December 2012 840 + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + Ada Reference Manual — 2012 Edition + +variant + +variant_part + +variant_part + +3.8.1 +3.8.1 + +3.8.1 + +component_list + +with_clause + +context_item + +3.8 + +10.1.2 +10.1.2 + +841 13 December 2012 + +Syntax Summary Annex P + + + + + Ada Reference Manual — 2012 Edition + +Annex Q +(informative) +Language-Defined Entities + +This annex lists the language-defined entities of the language. A list of language-defined library units can +be found in Annex A, “Predefined Language Environment”. + +1/2 + +Q.1 Language-Defined Packages + +This subclause lists all language-defined packages. + +1/3 + +Ada A.2(2) +Address_To_Access_Conversions + child of System 13.7.2(2) +Arithmetic + child of Ada.Calendar 9.6.1(8/2) +ASCII + in Standard A.1(36.3/2) +Assertions + child of Ada 11.4.2(12/2) +Asynchronous_Task_Control + child of Ada D.11(3/2) +Bounded + child of Ada.Strings A.4.4(3) +Bounded_IO + child of Ada.Text_IO A.10.11(3/2) + child of Ada.Wide_Text_IO A.11(4/3) + child of Ada.Wide_Wide_Text_IO A.11(4/3) +Bounded_Priority_Queues + child of Ada.Containers A.18.31(2/3) +Bounded_Synchronized_Queues + child of Ada.Containers A.18.29(2/3) +C + child of Interfaces B.3(4) +Calendar + child of Ada 9.6(10) +Characters + child of Ada A.3.1(2) +COBOL + child of Interfaces B.4(7) +Command_Line + child of Ada A.15(3) +Complex_Arrays + child of Ada.Numerics G.3.2(53/2) +Complex_Elementary_Functions + child of Ada.Numerics G.1.2(9/1) +Complex_Text_IO + child of Ada G.1.3(9.1/2) +Complex_Types + child of Ada.Numerics G.1.1(25/1) +Complex_IO + child of Ada.Text_IO G.1.3(3) + child of Ada.Wide_Text_IO G.1.4(1) + + child of Ada.Wide_Wide_Text_IO G.1.5(1/2) +Constants + child of Ada.Strings.Maps A.4.6(3/2) +Containers + child of Ada A.18.1(3/2) +Conversions + child of Ada.Characters A.3.4(2/2) + child of Ada.Strings.UTF_Encoding A.4.11(15/3) +Decimal + child of Ada F.2(2) +Decimal_Conversions + in Interfaces.COBOL B.4(31) +Decimal_IO + in Ada.Text_IO A.10.1(73) +Decimal_Output + in Ada.Text_IO.Editing F.3.3(11) +Direct_IO + child of Ada A.8.4(2) +Directories + child of Ada A.16(3/2) +Discrete_Random + child of Ada.Numerics A.5.2(17) +Dispatching + child of Ada D.2.1(1.2/3) +Dispatching_Domains + child of System.Multiprocessors D.16.1(3/3) +Doubly_Linked_Lists + child of Ada.Containers A.18.3(5/3) +Dynamic_Priorities + child of Ada D.5.1(3/2) +EDF + child of Ada.Dispatching D.2.6(9/2) + child of Ada.Synchronous_Task_Control D.10(5.2/3) +Editing + child of Ada.Text_IO F.3.3(3) + child of Ada.Wide_Text_IO F.3.4(1) + child of Ada.Wide_Wide_Text_IO F.3.5(1/2) +Elementary_Functions + child of Ada.Numerics A.5.1(9/1) +Enumeration_IO + in Ada.Text_IO A.10.1(79) + +843 13 December 2012 + +Language-Defined Entities Annex Q + + + Ada Reference Manual — 2012 Edition + +Environment_Variables + child of Ada A.17(3/2) +Exceptions + child of Ada 11.4.1(2/2) +Execution_Time + child of Ada D.14(3/2) +Finalization + child of Ada 7.6(4/3) +Fixed + child of Ada.Strings A.4.3(5) +Fixed_IO + in Ada.Text_IO A.10.1(68) +Float_Random + child of Ada.Numerics A.5.2(5) +Float_Text_IO + child of Ada A.10.9(33) +Float_Wide_Text_IO + child of Ada A.11(2/2) +Float_Wide_Wide_Text_IO + child of Ada A.11(3/2) +Float_IO + in Ada.Text_IO A.10.1(63) +Formatting + child of Ada.Calendar 9.6.1(15/2) +Fortran + child of Interfaces B.5(4) +Generic_Complex_Arrays + child of Ada.Numerics G.3.2(2/2) +Generic_Complex_Elementary_Functions + child of Ada.Numerics G.1.2(2/2) +Generic_Complex_Types + child of Ada.Numerics G.1.1(2/1) +Generic_Dispatching_Constructor + child of Ada.Tags 3.9(18.2/3) +Generic_Elementary_Functions + child of Ada.Numerics A.5.1(3) +Generic_Bounded_Length + in Ada.Strings.Bounded A.4.4(4) +Generic_Keys + in Ada.Containers.Hashed_Sets A.18.8(50/2) + in Ada.Containers.Ordered_Sets A.18.9(62/2) +Generic_Real_Arrays + child of Ada.Numerics G.3.1(2/2) +Generic_Sorting + in Ada.Containers.Doubly_Linked_Lists A.18.3(47/2) + in Ada.Containers.Vectors A.18.2(75/2) +Group_Budgets + child of Ada.Execution_Time D.14.2(3/3) +Handling + child of Ada.Characters A.3.2(2/2) + child of Ada.Wide_Characters A.3.5(3/3) + child of Ada.Wide_Wide_Characters A.3.6(1/3) +Hashed_Maps + child of Ada.Containers A.18.5(2/3) +Hashed_Sets + child of Ada.Containers A.18.8(2/3) +Hierarchical_File_Names + child of Ada.Directories A.16.1(3/3) +Indefinite_Doubly_Linked_Lists + child of Ada.Containers A.18.12(2/3) + +Indefinite_Hashed_Maps + child of Ada.Containers A.18.13(2/3) +Indefinite_Hashed_Sets + child of Ada.Containers A.18.15(2/3) +Indefinite_Holders + child of Ada.Containers A.18.18(5/3) +Indefinite_Multiway_Trees + child of Ada.Containers A.18.17(2/3) +Indefinite_Ordered_Maps + child of Ada.Containers A.18.14(2/3) +Indefinite_Ordered_Sets + child of Ada.Containers A.18.16(2/3) +Indefinite_Vectors + child of Ada.Containers A.18.11(2/3) +Information + child of Ada.Directories A.16(124/2) +Integer_Text_IO + child of Ada A.10.8(21) +Integer_Wide_Text_IO + child of Ada A.11(2/2) +Integer_Wide_Wide_Text_IO + child of Ada A.11(3/2) +Integer_IO + in Ada.Text_IO A.10.1(52) +Interfaces B.2(3) +Interrupts + child of Ada C.3.2(2/3) + child of Ada.Execution_Time D.14.3(3/3) +IO_Exceptions + child of Ada A.13(3) +Iterator_Interfaces + child of Ada 5.5.1(2/3) +Latin_1 + child of Ada.Characters A.3.3(3) +List_Iterator_Interfaces + in Ada.Containers.Doubly_Linked_Lists A.18.3(9.2/3) +Locales + child of Ada A.19(3/3) +Machine_Code + child of System 13.8(7) +Map_Iterator_Interfaces + in Ada.Containers.Hashed_Maps A.18.5(6.2/3) + in Ada.Containers.Ordered_Maps A.18.6(7.2/3) +Maps + child of Ada.Strings A.4.2(3/2) +Modular_IO + in Ada.Text_IO A.10.1(57) +Multiprocessors + child of System D.16(3/3) +Multiway_Trees + child of Ada.Containers A.18.10(7/3) +Names + child of Ada.Interrupts C.3.2(12) +Non_Preemptive + child of Ada.Dispatching D.2.4(2.2/3) +Numerics + child of Ada A.5(3/2) +Ordered_Maps + child of Ada.Containers A.18.6(2/3) + +Q.1 Language-Defined Packages + +13 December 2012 844 + + Ordered_Sets + child of Ada.Containers A.18.9(2/3) +Pointers + child of Interfaces.C B.3.2(4) +Real_Arrays + child of Ada.Numerics G.3.1(31/2) +Real_Time + child of Ada D.8(3) +Round_Robin + child of Ada.Dispatching D.2.5(4/2) +RPC + child of System E.5(3) +Sequential_IO + child of Ada A.8.1(2) +Set_Iterator_Interfaces + in Ada.Containers.Hashed_Sets A.18.8(6.2/3) + in Ada.Containers.Ordered_Sets A.18.9(7.2/3) +Single_Precision_Complex_Types + in Interfaces.Fortran B.5(8) +Standard A.1(4) +Storage_Elements + child of System 13.7.1(2/2) +Storage_IO + child of Ada A.9(3) +Storage_Pools + child of System 13.11(5) +Stream_IO + child of Ada.Streams A.12.1(3/3) +Streams + child of Ada 13.13.1(2) +Strings + child of Ada A.4.1(3) + child of Ada.Strings.UTF_Encoding A.4.11(22/3) + child of Interfaces.C B.3.1(3) +Subpools + child of System.Storage_Pools 13.11.4(3/3) +Synchronized_Queue_Interfaces + child of Ada.Containers A.18.27(3/3) +Synchronous_Barriers + child of Ada D.10.1(3/3) +Synchronous_Task_Control + child of Ada D.10(3/2) +System 13.7(3/2) +Tags + child of Ada 3.9(6/2) +Task_Attributes + child of Ada C.7.2(2) +Task_Identification + child of Ada C.7.1(2/2) +Task_Termination + child of Ada C.7.3(2/2) +Text_Streams + child of Ada.Text_IO A.12.2(3) + child of Ada.Wide_Text_IO A.12.3(3) + child of Ada.Wide_Wide_Text_IO A.12.4(3/2) +Text_IO + child of Ada A.10.1(2) +Time_Zones + child of Ada.Calendar 9.6.1(2/2) + +Ada Reference Manual — 2012 Edition + +Timers + child of Ada.Execution_Time D.14.1(3/2) +Timing_Events + child of Ada.Real_Time D.15(3/2) +Tree_Iterator_Interfaces + in Ada.Containers.Multiway_Trees A.18.10(13/3) +Unbounded + child of Ada.Strings A.4.5(3) +Unbounded_IO + child of Ada.Text_IO A.10.12(3/2) + child of Ada.Wide_Text_IO A.11(5/3) + child of Ada.Wide_Wide_Text_IO A.11(5/3) +Unbounded_Priority_Queues + child of Ada.Containers A.18.30(2/3) +Unbounded_Synchronized_Queues + child of Ada.Containers A.18.28(2/3) +UTF_Encoding + child of Ada.Strings A.4.11(3/3) +Vector_Iterator_Interfaces + in Ada.Containers.Vectors A.18.2(11.2/3) +Vectors + child of Ada.Containers A.18.2(6/3) +Wide_Bounded + child of Ada.Strings A.4.7(1/3) +Wide_Constants + child of Ada.Strings.Wide_Maps A.4.7(1/3), A.4.8(28/2) +Wide_Equal_Case_Insensitive + child of Ada.Strings A.4.7(1/3) +Wide_Fixed + child of Ada.Strings A.4.7(1/3) +Wide_Hash + child of Ada.Strings A.4.7(1/3) +Wide_Hash_Case_Insensitive + child of Ada.Strings A.4.7(1/3) +Wide_Maps + child of Ada.Strings A.4.7(3) +Wide_Text_IO + child of Ada A.11(2/2) +Wide_Unbounded + child of Ada.Strings A.4.7(1/3) +Wide_Characters + child of Ada A.3.1(4/2) +Wide_Strings + child of Ada.Strings.UTF_Encoding A.4.11(30/3) +Wide_Wide_Constants + child of Ada.Strings.Wide_Wide_Maps A.4.8(1/3) +Wide_Wide_Equal_Case_Insensitive + child of Ada.Strings A.4.8(1/3) +Wide_Wide_Hash + child of Ada.Strings A.4.8(1/3) +Wide_Wide_Hash_Case_Insensitive + child of Ada.Strings A.4.8(1/3) +Wide_Wide_Text_IO + child of Ada A.11(3/2) +Wide_Wide_Bounded + child of Ada.Strings A.4.8(1/3) +Wide_Wide_Characters + child of Ada A.3.1(6/2) +Wide_Wide_Fixed + child of Ada.Strings A.4.8(1/3) + +845 13 December 2012 + +Language-Defined Packages Q.1 + + Ada Reference Manual — 2012 Edition + +Wide_Wide_Maps + child of Ada.Strings A.4.8(3/2) +Wide_Wide_Strings + child of Ada.Strings.UTF_Encoding A.4.11(38/3) + +Wide_Wide_Unbounded + child of Ada.Strings A.4.8(1/3) + +Q.2 Language-Defined Types and Subtypes + +1/3 + +This subclause lists all language-defined types and subtypes. + +Address + in System 13.7(12) +Alignment + in Ada.Strings A.4.1(6) +Alphanumeric + in Interfaces.COBOL B.4(16/3) +Any_Priority subtype of Integer + in System 13.7(16) +Attribute_Handle + in Ada.Task_Attributes C.7.2(3) +Barrier_Limit subtype of Positive + in Ada.Synchronous_Barriers D.10.1(4/3) +Binary + in Interfaces.COBOL B.4(10) +Binary_Format + in Interfaces.COBOL B.4(24) +Bit_Order + in System 13.7(15/2) +Boolean + in Standard A.1(5) +Bounded_String + in Ada.Strings.Bounded A.4.4(6) +Buffer_Type subtype of Storage_Array + in Ada.Storage_IO A.9(4) +Byte + in Interfaces.COBOL B.4(29/3) +Byte_Array + in Interfaces.COBOL B.4(29/3) +C_float + in Interfaces.C B.3(15) +Cause_Of_Termination + in Ada.Task_Termination C.7.3(3/2) +char + in Interfaces.C B.3(19) +char16_array + in Interfaces.C B.3(39.5/3) +char16_t + in Interfaces.C B.3(39.2/2) +char32_array + in Interfaces.C B.3(39.14/3) +char32_t + in Interfaces.C B.3(39.11/2) +char_array + in Interfaces.C B.3(23/3) +char_array_access + in Interfaces.C.Strings B.3.1(4) + +Character + in Standard A.1(35/3) +Character_Mapping + in Ada.Strings.Maps A.4.2(20/2) +Character_Mapping_Function + in Ada.Strings.Maps A.4.2(25) +Character_Range + in Ada.Strings.Maps A.4.2(6) +Character_Ranges + in Ada.Strings.Maps A.4.2(7) +Character_Sequence subtype of String + in Ada.Strings.Maps A.4.2(16) +Character_Set + in Ada.Strings.Maps A.4.2(4/2) + in Interfaces.Fortran B.5(11) +chars_ptr + in Interfaces.C.Strings B.3.1(5/2) +chars_ptr_array + in Interfaces.C.Strings B.3.1(6/2) +COBOL_Character + in Interfaces.COBOL B.4(13) +Complex + in Ada.Numerics.Generic_Complex_Types G.1.1(3) + in Interfaces.Fortran B.5(9) +Complex_Matrix + in Ada.Numerics.Generic_Complex_Arrays G.3.2(4/2) +Complex_Vector + in Ada.Numerics.Generic_Complex_Arrays G.3.2(4/2) +Constant_Reference_Type + in Ada.Containers.Indefinite_Holders A.18.18(16/3) + in Ada.Containers.Multiway_Trees A.18.10(28/3) +Controlled + in Ada.Finalization 7.6(5/2) +Count + in Ada.Direct_IO A.8.4(4) + in Ada.Streams.Stream_IO A.12.1(7) + in Ada.Text_IO A.10.1(5) +Count_Type + in Ada.Containers A.18.1(5/2) +Country_Code + in Ada.Locales A.19(4/3) +CPU subtype of CPU_Range + in System.Multiprocessors D.16(4/3) +CPU_Range + in System.Multiprocessors D.16(4/3) +CPU_Time + in Ada.Execution_Time D.14(4/2) + +Q.1 Language-Defined Packages + +13 December 2012 846 + + + Ada Reference Manual — 2012 Edition + +Cursor + in Ada.Containers.Doubly_Linked_Lists A.18.3(7/2) + in Ada.Containers.Hashed_Maps A.18.5(4/2) + in Ada.Containers.Hashed_Sets A.18.8(4/2) + in Ada.Containers.Multiway_Trees A.18.10(9/3) + in Ada.Containers.Ordered_Maps A.18.6(5/2) + in Ada.Containers.Ordered_Sets A.18.9(5/2) + in Ada.Containers.Vectors A.18.2(9/2) +Day_Count + in Ada.Calendar.Arithmetic 9.6.1(10/2) +Day_Duration subtype of Duration + in Ada.Calendar 9.6(11/2) +Day_Name + in Ada.Calendar.Formatting 9.6.1(17/2) +Day_Number subtype of Integer + in Ada.Calendar 9.6(11/2) +Deadline subtype of Time + in Ada.Dispatching.EDF D.2.6(9/2) +Decimal_Element + in Interfaces.COBOL B.4(12/3) +Direction + in Ada.Strings A.4.1(6) +Directory_Entry_Type + in Ada.Directories A.16(29/2) +Dispatching_Domain + in System.Multiprocessors.Dispatching_Domains + +D.16.1(5/3) +Display_Format + in Interfaces.COBOL B.4(22) +double + in Interfaces.C B.3(16) +Double_Precision + in Interfaces.Fortran B.5(6) +Duration + in Standard A.1(43) +Encoding_Scheme + in Ada.Strings.UTF_Encoding A.4.11(4/3) +Exception_Id + in Ada.Exceptions 11.4.1(2/2) +Exception_Occurrence + in Ada.Exceptions 11.4.1(3/2) +Exception_Occurrence_Access + in Ada.Exceptions 11.4.1(3/2) +Exit_Status + in Ada.Command_Line A.15(7) +Extended_Index subtype of Index_Type'Base + in Ada.Containers.Vectors A.18.2(7/2) +Field subtype of Integer + in Ada.Text_IO A.10.1(6) +File_Access + in Ada.Text_IO A.10.1(18) +File_Kind + in Ada.Directories A.16(22/2) +File_Mode + in Ada.Direct_IO A.8.4(4) + in Ada.Sequential_IO A.8.1(4) + in Ada.Streams.Stream_IO A.12.1(6) + in Ada.Text_IO A.10.1(4) +File_Size + in Ada.Directories A.16(23/2) + +File_Type + in Ada.Direct_IO A.8.4(3) + in Ada.Sequential_IO A.8.1(3) + in Ada.Streams.Stream_IO A.12.1(5) + in Ada.Text_IO A.10.1(3) +Filter_Type + in Ada.Directories A.16(30/2) +Float + in Standard A.1(21) +Floating + in Interfaces.COBOL B.4(9) +Fortran_Character + in Interfaces.Fortran B.5(12/3) +Fortran_Integer + in Interfaces.Fortran B.5(5) +Forward_Iterator + in Ada.Iterator_Interfaces 5.5.1(3/3) +Generator + in Ada.Numerics.Discrete_Random A.5.2(19) + in Ada.Numerics.Float_Random A.5.2(7) +Group_Budget + in Ada.Execution_Time.Group_Budgets D.14.2(4/3) +Group_Budget_Handler + in Ada.Execution_Time.Group_Budgets D.14.2(5/2) +Hash_Type + in Ada.Containers A.18.1(4/2) +Holder + in Ada.Containers.Indefinite_Holders A.18.18(6/3) +Hour_Number subtype of Natural + in Ada.Calendar.Formatting 9.6.1(20/2) +Imaginary + in Ada.Numerics.Generic_Complex_Types G.1.1(4/2) +Imaginary subtype of Imaginary + in Interfaces.Fortran B.5(10) +int + in Interfaces.C B.3(7) +Integer + in Standard A.1(12) +Integer_Address + in System.Storage_Elements 13.7.1(10/3) +Interrupt_Id + in Ada.Interrupts C.3.2(2/3) +Interrupt_Priority subtype of Any_Priority + in System 13.7(16) +ISO_646 subtype of Character + in Ada.Characters.Handling A.3.2(9) +Language_Code + in Ada.Locales A.19(4/3) +Leap_Seconds_Count subtype of Integer + in Ada.Calendar.Arithmetic 9.6.1(11/2) +Length_Range subtype of Natural + in Ada.Strings.Bounded A.4.4(8) +Limited_Controlled + in Ada.Finalization 7.6(7/2) +List + in Ada.Containers.Doubly_Linked_Lists A.18.3(6/3) +Logical + in Interfaces.Fortran B.5(7) +long + in Interfaces.C B.3(7) + +847 13 December 2012 + +Language-Defined Types and Subtypes Q.2 + + Ada Reference Manual — 2012 Edition + +Long_Binary + in Interfaces.COBOL B.4(10) +long_double + in Interfaces.C B.3(17) +Long_Floating + in Interfaces.COBOL B.4(9) +Map + in Ada.Containers.Hashed_Maps A.18.5(3/3) + in Ada.Containers.Ordered_Maps A.18.6(4/3) +Membership + in Ada.Strings A.4.1(6) +Minute_Number subtype of Natural + in Ada.Calendar.Formatting 9.6.1(20/2) +Month_Number subtype of Integer + in Ada.Calendar 9.6(11/2) +Name + in System 13.7(4) +Name_Case_Kind + in Ada.Directories A.16(20.1/3) +Natural subtype of Integer + in Standard A.1(13) +Number_Base subtype of Integer + in Ada.Text_IO A.10.1(6) +Numeric + in Interfaces.COBOL B.4(20/3) +Packed_Decimal + in Interfaces.COBOL B.4(12/3) +Packed_Format + in Interfaces.COBOL B.4(26) +Parameterless_Handler + in Ada.Interrupts C.3.2(2/3) +Params_Stream_Type + in System.RPC E.5(6) +Partition_Id + in System.RPC E.5(4) +Picture + in Ada.Text_IO.Editing F.3.3(4) +plain_char + in Interfaces.C B.3(11) +Pointer + in Interfaces.C.Pointers B.3.2(5) +Positive subtype of Integer + in Standard A.1(13) +Positive_Count subtype of Count + in Ada.Direct_IO A.8.4(4) + in Ada.Streams.Stream_IO A.12.1(7) + in Ada.Text_IO A.10.1(5) +Priority subtype of Any_Priority + in System 13.7(16) +ptrdiff_t + in Interfaces.C B.3(12) +Queue + in Ada.Containers.Bounded_Priority_Queues A.18.31(4/3) + in Ada.Containers.Bounded_Synchronized_Queues + +A.18.29(4/3) + + in Ada.Containers.Synchronized_Queue_Interfaces + +A.18.27(4/3) + + in Ada.Containers.Unbounded_Priority_Queues + +A.18.30(4/3) + + in Ada.Containers.Unbounded_Synchronized_Queues + +A.18.28(4/3) + +Real + in Interfaces.Fortran B.5(6) +Real_Matrix + in Ada.Numerics.Generic_Real_Arrays G.3.1(4/2) +Real_Vector + in Ada.Numerics.Generic_Real_Arrays G.3.1(4/2) +Reference_Type + in Ada.Containers.Doubly_Linked_Lists A.18.3(17.2/3) + in Ada.Containers.Hashed_Maps A.18.5(17.2/3) + in Ada.Containers.Hashed_Sets A.18.8(58.1/3) + in Ada.Containers.Indefinite_Holders A.18.18(17/3) + in Ada.Containers.Multiway_Trees A.18.10(29/3) + in Ada.Containers.Ordered_Maps A.18.6(16.2/3) + in Ada.Containers.Ordered_Sets A.18.9(73.1/3) + in Ada.Containers.Vectors A.18.2(34.2/3) +Reversible_Iterator + in Ada.Iterator_Interfaces 5.5.1(4/3) +Root_Storage_Pool + in System.Storage_Pools 13.11(6/2) +Root_Storage_Pool_With_Subpools + in System.Storage_Pools.Subpools 13.11.4(4/3) +Root_Stream_Type + in Ada.Streams 13.13.1(3/2) +Root_Subpool + in System.Storage_Pools.Subpools 13.11.4(5/3) +RPC_Receiver + in System.RPC E.5(11) +Search_Type + in Ada.Directories A.16(31/2) +Second_Duration subtype of Day_Duration + in Ada.Calendar.Formatting 9.6.1(20/2) +Second_Number subtype of Natural + in Ada.Calendar.Formatting 9.6.1(20/2) +Seconds_Count + in Ada.Real_Time D.8(15) +Set + in Ada.Containers.Hashed_Sets A.18.8(3/3) + in Ada.Containers.Ordered_Sets A.18.9(4/3) +short + in Interfaces.C B.3(7) +signed_char + in Interfaces.C B.3(8) +size_t + in Interfaces.C B.3(13) +State + in Ada.Numerics.Discrete_Random A.5.2(23) + in Ada.Numerics.Float_Random A.5.2(11) +Storage_Array + in System.Storage_Elements 13.7.1(5) +Storage_Count subtype of Storage_Offset + in System.Storage_Elements 13.7.1(4) +Storage_Element + in System.Storage_Elements 13.7.1(5) +Storage_Offset + in System.Storage_Elements 13.7.1(3) +Stream_Access + in Ada.Streams.Stream_IO A.12.1(4) + in Ada.Text_IO.Text_Streams A.12.2(3) + +Q.2 Language-Defined Types and Subtypes + +13 December 2012 848 + + Ada Reference Manual — 2012 Edition + + in Ada.Wide_Text_IO.Text_Streams A.12.3(3) + in Ada.Wide_Wide_Text_IO.Text_Streams A.12.4(3/2) +Stream_Element + in Ada.Streams 13.13.1(4/1) +Stream_Element_Array + in Ada.Streams 13.13.1(4/1) +Stream_Element_Count subtype of Stream_Element_Offset + in Ada.Streams 13.13.1(4/1) +Stream_Element_Offset + in Ada.Streams 13.13.1(4/1) +String + in Standard A.1(37/3) +String_Access + in Ada.Strings.Unbounded A.4.5(7) +Subpool_Handle + in System.Storage_Pools.Subpools 13.11.4(6/3) +Suspension_Object + in Ada.Synchronous_Task_Control D.10(4) +Synchronous_Barrier + in Ada.Synchronous_Barriers D.10.1(5/3) +Tag + in Ada.Tags 3.9(6/2) +Tag_Array + in Ada.Tags 3.9(7.3/2) +Task_Array + in Ada.Execution_Time.Group_Budgets D.14.2(6/2) +Task_Id + in Ada.Task_Identification C.7.1(2/2) +Termination_Handler + in Ada.Task_Termination C.7.3(4/2) +Time + in Ada.Calendar 9.6(10) + in Ada.Real_Time D.8(4) +Time_Offset + in Ada.Calendar.Time_Zones 9.6.1(4/2) +Time_Span + in Ada.Real_Time D.8(5) +Timer + in Ada.Execution_Time.Timers D.14.1(4/2) +Timer_Handler + in Ada.Execution_Time.Timers D.14.1(5/2) +Timing_Event + in Ada.Real_Time.Timing_Events D.15(4/2) +Timing_Event_Handler + in Ada.Real_Time.Timing_Events D.15(4/2) +Tree + in Ada.Containers.Multiway_Trees A.18.10(8/3) +Trim_End + in Ada.Strings A.4.1(6) +Truncation + in Ada.Strings A.4.1(6) +Type_Set + in Ada.Text_IO A.10.1(7) +Unbounded_String + in Ada.Strings.Unbounded A.4.5(4/2) +Uniformly_Distributed subtype of Float + in Ada.Numerics.Float_Random A.5.2(8) + +unsigned + in Interfaces.C B.3(9) +unsigned_char + in Interfaces.C B.3(10) +unsigned_long + in Interfaces.C B.3(9) +unsigned_short + in Interfaces.C B.3(9) +UTF_16_Wide_String subtype of Wide_String + in Ada.Strings.UTF_Encoding A.4.11(7/3) +UTF_8_String subtype of String + in Ada.Strings.UTF_Encoding A.4.11(6/3) +UTF_String subtype of String + in Ada.Strings.UTF_Encoding A.4.11(5/3) +Vector + in Ada.Containers.Vectors A.18.2(8/3) +wchar_array + in Interfaces.C B.3(33/3) +wchar_t + in Interfaces.C B.3(30/1) +Wide_Character + in Standard A.1(36.1/3) +Wide_Character_Mapping + in Ada.Strings.Wide_Maps A.4.7(20/2) +Wide_Character_Mapping_Function + in Ada.Strings.Wide_Maps A.4.7(26) +Wide_Character_Range + in Ada.Strings.Wide_Maps A.4.7(6) +Wide_Character_Ranges + in Ada.Strings.Wide_Maps A.4.7(7) +Wide_Character_Sequence subtype of Wide_String + in Ada.Strings.Wide_Maps A.4.7(16) +Wide_Character_Set + in Ada.Strings.Wide_Maps A.4.7(4/2) +Wide_String + in Standard A.1(41/3) +Wide_Wide_Character + in Standard A.1(36.2/3) +Wide_Wide_Character_Mapping + in Ada.Strings.Wide_Wide_Maps A.4.8(20/2) +Wide_Wide_Character_Mapping_Function + in Ada.Strings.Wide_Wide_Maps A.4.8(26/2) +Wide_Wide_Character_Range + in Ada.Strings.Wide_Wide_Maps A.4.8(6/2) +Wide_Wide_Character_Ranges + in Ada.Strings.Wide_Wide_Maps A.4.8(7/2) +Wide_Wide_Character_Sequence subtype of + +Wide_Wide_String + + in Ada.Strings.Wide_Wide_Maps A.4.8(16/2) +Wide_Wide_Character_Set + in Ada.Strings.Wide_Wide_Maps A.4.8(4/2) +Wide_Wide_String + in Standard A.1(42.1/3) +Year_Number subtype of Integer + in Ada.Calendar 9.6(11/2) + +849 13 December 2012 + +Language-Defined Types and Subtypes Q.2 + + Ada Reference Manual — 2012 Edition + +Q.3 Language-Defined Subprograms + +1/3 + +This subclause lists all language-defined subprograms. + +Abort_Task in Ada.Task_Identification C.7.1(3/3) +Activation_Is_Complete + in Ada.Task_Identification C.7.1(4/3) +Actual_Quantum + in Ada.Dispatching.Round_Robin D.2.5(4/2) +Ada.Unchecked_Deallocate_Subpool + child of Ada 13.11.5(3/3) +Add + in Ada.Execution_Time.Group_Budgets D.14.2(9/2) +Add_Task + in Ada.Execution_Time.Group_Budgets D.14.2(8/2) +Adjust in Ada.Finalization 7.6(6/2) +Allocate + in System.Storage_Pools 13.11(7) + in System.Storage_Pools.Subpools 13.11.4(14/3) +Allocate_From_Subpool + in System.Storage_Pools.Subpools 13.11.4(11/3) +Ancestor_Find + in Ada.Containers.Multiway_Trees A.18.10(40/3) +Append + in Ada.Containers.Doubly_Linked_Lists A.18.3(23/2) + in Ada.Containers.Vectors A.18.2(46/2), A.18.2(47/2) + in Ada.Strings.Bounded A.4.4(13), A.4.4(14), A.4.4(15), +A.4.4(16), A.4.4(17), A.4.4(18), A.4.4(19), A.4.4(20) + in Ada.Strings.Unbounded A.4.5(12), A.4.5(13), A.4.5(14) +Append_Child + in Ada.Containers.Multiway_Trees A.18.10(52/3) +Arccos + in Ada.Numerics.Generic_Complex_Elementary_Functions + +G.1.2(5) + + in Ada.Numerics.Generic_Elementary_Functions A.5.1(6) +Arccosh + in Ada.Numerics.Generic_Complex_Elementary_Functions + +G.1.2(7) + + in Ada.Numerics.Generic_Elementary_Functions A.5.1(7) +Arccot + in Ada.Numerics.Generic_Complex_Elementary_Functions + +G.1.2(5) + + in Ada.Numerics.Generic_Elementary_Functions A.5.1(6) +Arccoth + in Ada.Numerics.Generic_Complex_Elementary_Functions + +G.1.2(7) + + in Ada.Numerics.Generic_Elementary_Functions A.5.1(7) +Arcsin + in Ada.Numerics.Generic_Complex_Elementary_Functions + +G.1.2(5) + + in Ada.Numerics.Generic_Elementary_Functions A.5.1(6) +Arcsinh + in Ada.Numerics.Generic_Complex_Elementary_Functions + +G.1.2(7) + + in Ada.Numerics.Generic_Elementary_Functions A.5.1(7) + +Arctan + in Ada.Numerics.Generic_Complex_Elementary_Functions + +G.1.2(5) + + in Ada.Numerics.Generic_Elementary_Functions A.5.1(6) +Arctanh + in Ada.Numerics.Generic_Complex_Elementary_Functions + +G.1.2(7) + + in Ada.Numerics.Generic_Elementary_Functions A.5.1(7) +Argument + in Ada.Command_Line A.15(5) + in Ada.Numerics.Generic_Complex_Arrays G.3.2(10/2), + +G.3.2(31/2) + + in Ada.Numerics.Generic_Complex_Types G.1.1(10) +Argument_Count in Ada.Command_Line A.15(4) +Assert in Ada.Assertions 11.4.2(14/2) +Assign + in Ada.Containers.Doubly_Linked_Lists A.18.3(17.5/3) + in Ada.Containers.Hashed_Maps A.18.5(17.7/3) + in Ada.Containers.Hashed_Sets A.18.8(17.3/3) + in Ada.Containers.Indefinite_Holders A.18.18(20/3) + in Ada.Containers.Multiway_Trees A.18.10(32/3) + in Ada.Containers.Ordered_Maps A.18.6(16.7/3) + in Ada.Containers.Ordered_Sets A.18.9(16.3/3) + in Ada.Containers.Vectors A.18.2(34.7/3) +Assign_Task + in System.Multiprocessors.Dispatching_Domains + +D.16.1(11/3) + +Attach_Handler in Ada.Interrupts C.3.2(7) +Base_Name in Ada.Directories A.16(19/2) +Blank_When_Zero + in Ada.Text_IO.Editing F.3.3(7) +Bounded_Slice in Ada.Strings.Bounded A.4.4(28.1/2), + +A.4.4(28.2/2) +Budget_Has_Expired + in Ada.Execution_Time.Group_Budgets D.14.2(9/2) +Budget_Remaining + in Ada.Execution_Time.Group_Budgets D.14.2(9/2) +Cancel_Handler + in Ada.Execution_Time.Group_Budgets D.14.2(10/2) + in Ada.Execution_Time.Timers D.14.1(7/2) + in Ada.Real_Time.Timing_Events D.15(5/2) +Capacity + in Ada.Containers.Hashed_Maps A.18.5(8/2) + in Ada.Containers.Hashed_Sets A.18.8(10/2) + in Ada.Containers.Vectors A.18.2(19/2) +Ceiling + in Ada.Containers.Ordered_Maps A.18.6(41/2) + in Ada.Containers.Ordered_Sets A.18.9(51/2), A.18.9(71/2) +Character_Set_Version + in Ada.Wide_Characters.Handling A.3.5(4/3) +Child_Count + in Ada.Containers.Multiway_Trees A.18.10(46/3) + +Q.3 Language-Defined Subprograms + +13 December 2012 850 + + + Ada Reference Manual — 2012 Edition + +Child_Depth + in Ada.Containers.Multiway_Trees A.18.10(47/3) +Clear + in Ada.Containers.Doubly_Linked_Lists A.18.3(13/2) + in Ada.Containers.Hashed_Maps A.18.5(12/2) + in Ada.Containers.Hashed_Sets A.18.8(14/2) + in Ada.Containers.Indefinite_Holders A.18.18(11/3) + in Ada.Containers.Multiway_Trees A.18.10(23/3) + in Ada.Containers.Ordered_Maps A.18.6(11/2) + in Ada.Containers.Ordered_Sets A.18.9(13/2) + in Ada.Containers.Vectors A.18.2(24/2) + in Ada.Environment_Variables A.17(7/2) +Clock + in Ada.Calendar 9.6(12) + in Ada.Execution_Time D.14(5/2) + in Ada.Execution_Time.Interrupts D.14.3(3/3) + in Ada.Real_Time D.8(6) +Clock_For_Interrupts + in Ada.Execution_Time D.14(9.3/3) +Close + in Ada.Direct_IO A.8.4(8) + in Ada.Sequential_IO A.8.1(8) + in Ada.Streams.Stream_IO A.12.1(10) + in Ada.Text_IO A.10.1(11) +Col in Ada.Text_IO A.10.1(37) +Command_Name in Ada.Command_Line A.15(6) +Compose + in Ada.Directories A.16(20/2) + in Ada.Directories.Hierarchical_File_Names A.16.1(14/3) +Compose_From_Cartesian + in Ada.Numerics.Generic_Complex_Arrays G.3.2(9/2), + +G.3.2(29/2) + + in Ada.Numerics.Generic_Complex_Types G.1.1(8) +Compose_From_Polar + in Ada.Numerics.Generic_Complex_Arrays G.3.2(11/2), + +G.3.2(32/2) + + in Ada.Numerics.Generic_Complex_Types G.1.1(11) +Conjugate + in Ada.Numerics.Generic_Complex_Arrays G.3.2(13/2), + +G.3.2(34/2) + +Contains + in Ada.Containers.Doubly_Linked_Lists A.18.3(43/2) + in Ada.Containers.Hashed_Maps A.18.5(32/2) + in Ada.Containers.Hashed_Sets A.18.8(44/2), A.18.8(57/2) + in Ada.Containers.Multiway_Trees A.18.10(41/3) + in Ada.Containers.Ordered_Maps A.18.6(42/2) + in Ada.Containers.Ordered_Sets A.18.9(52/2), A.18.9(72/2) + in Ada.Containers.Vectors A.18.2(71/2) +Continue + in Ada.Asynchronous_Task_Control D.11(3/2) +Convert + in Ada.Strings.UTF_Encoding.Conversions A.4.11(16/3), +A.4.11(17/3), A.4.11(18/3), A.4.11(19/3), A.4.11(20/3) + +Copy + in Ada.Containers.Doubly_Linked_Lists A.18.3(17.6/3) + in Ada.Containers.Hashed_Maps A.18.5(17.8/3) + in Ada.Containers.Hashed_Sets A.18.8(17.4/3) + in Ada.Containers.Indefinite_Holders A.18.18(21/3), + +A.18.20(10/3), A.18.21(13/3), A.18.22(10/3), +A.18.23(13/3), A.18.24(10/3) + + in Ada.Containers.Multiway_Trees A.18.10(33/3) + in Ada.Containers.Ordered_Maps A.18.6(16.8/3) + in Ada.Containers.Ordered_Sets A.18.9(16.4/3) + in Ada.Containers.Vectors A.18.2(34.8/3) +Copy_Array in Interfaces.C.Pointers B.3.2(15) +Copy_File in Ada.Directories A.16(13/2) +Copy_Subtree + in Ada.Containers.Multiway_Trees A.18.10(54/3) +Copy_Terminated_Array + in Interfaces.C.Pointers B.3.2(14) +Cos + in Ada.Numerics.Generic_Complex_Elementary_Functions + +G.1.2(4) + + in Ada.Numerics.Generic_Elementary_Functions A.5.1(5) +Cosh + in Ada.Numerics.Generic_Complex_Elementary_Functions + +G.1.2(6) + + in Ada.Numerics.Generic_Elementary_Functions A.5.1(7) +Cot + in Ada.Numerics.Generic_Complex_Elementary_Functions + + in Ada.Numerics.Generic_Complex_Types G.1.1(12), + +G.1.2(4) + +G.1.1(15) + +Constant_Reference + in Ada.Containers.Doubly_Linked_Lists A.18.3(17.3/3) + in Ada.Containers.Hashed_Maps A.18.5(17.3/3), + +A.18.5(17.5/3) + + in Ada.Containers.Hashed_Sets A.18.8(17.2/3), + +A.18.8(58.3/3) + + in Ada.Containers.Indefinite_Holders A.18.18(18/3) + in Ada.Containers.Multiway_Trees A.18.10(30/3) + in Ada.Containers.Ordered_Maps A.18.6(16.3/3), + +A.18.6(16.5/3) + + in Ada.Containers.Ordered_Sets A.18.9(16.2/3), + +A.18.9(73.3/3) + + in Ada.Containers.Vectors A.18.2(34.3/3), A.18.2(34.5/3) +Containing_Directory + in Ada.Directories A.16(17/2) + in Ada.Directories.Hierarchical_File_Names A.16.1(11/3) + + in Ada.Numerics.Generic_Elementary_Functions A.5.1(5) +Coth + in Ada.Numerics.Generic_Complex_Elementary_Functions + +G.1.2(6) + + in Ada.Numerics.Generic_Elementary_Functions A.5.1(7) +Count + in Ada.Strings.Bounded A.4.4(48), A.4.4(49), A.4.4(50) + in Ada.Strings.Fixed A.4.3(13), A.4.3(14), A.4.3(15) + in Ada.Strings.Unbounded A.4.5(43), A.4.5(44), A.4.5(45) +Country in Ada.Locales A.19(6/3) +Create + in Ada.Direct_IO A.8.4(6) + in Ada.Sequential_IO A.8.1(6) + in Ada.Streams.Stream_IO A.12.1(8) + in Ada.Text_IO A.10.1(9) + in System.Multiprocessors.Dispatching_Domains + +D.16.1(7/3) + +Create_Directory in Ada.Directories A.16(7/2) +Create_Path in Ada.Directories A.16(9/2) + +851 13 December 2012 + +Language-Defined Subprograms Q.3 + + Ada Reference Manual — 2012 Edition + +Create_Subpool + in System.Storage_Pools.Subpools 13.11.4(7/3) +Current_Directory in Ada.Directories A.16(5/2) +Current_Error in Ada.Text_IO A.10.1(17), A.10.1(20) +Current_Handler + in Ada.Execution_Time.Group_Budgets D.14.2(10/2) + in Ada.Execution_Time.Timers D.14.1(7/2) + in Ada.Interrupts C.3.2(6) + in Ada.Real_Time.Timing_Events D.15(5/2) +Current_Input in Ada.Text_IO A.10.1(17), A.10.1(20) +Current_Output in Ada.Text_IO A.10.1(17), A.10.1(20) +Current_State + in Ada.Synchronous_Task_Control D.10(4) +Current_Task + in Ada.Task_Identification C.7.1(3/3) +Current_Task_Fallback_Handler + in Ada.Task_Termination C.7.3(5/2) +Current_Use + in Ada.Containers.Bounded_Priority_Queues A.18.31(7/3) + in Ada.Containers.Bounded_Synchronized_Queues + +A.18.29(6/3) + + in Ada.Containers.Synchronized_Queue_Interfaces + +A.18.27(7/3) + + in Ada.Containers.Unbounded_Priority_Queues + +A.18.30(7/3) + + in Ada.Containers.Unbounded_Synchronized_Queues + +A.18.28(6/3) + +Day + in Ada.Calendar 9.6(13) + in Ada.Calendar.Formatting 9.6.1(23/2) +Day_of_Week + in Ada.Calendar.Formatting 9.6.1(18/2) +Deallocate + in System.Storage_Pools 13.11(8) + in System.Storage_Pools.Subpools 13.11.4(15/3) +Deallocate_Subpool + in System.Storage_Pools.Subpools 13.11.4(12/3) +Decode + in Ada.Strings.UTF_Encoding.Strings A.4.11(26/3), + + in Ada.Containers.Ordered_Maps A.18.6(24/2), + +A.18.6(25/2) + + in Ada.Containers.Ordered_Sets A.18.9(23/2), A.18.9(24/2), + +A.18.9(68/2) + + in Ada.Containers.Vectors A.18.2(50/2), A.18.2(51/2) + in Ada.Direct_IO A.8.4(8) + in Ada.Sequential_IO A.8.1(8) + in Ada.Streams.Stream_IO A.12.1(10) + in Ada.Strings.Bounded A.4.4(64), A.4.4(65) + in Ada.Strings.Fixed A.4.3(29), A.4.3(30) + in Ada.Strings.Unbounded A.4.5(59), A.4.5(60) + in Ada.Text_IO A.10.1(11) +Delete_Children + in Ada.Containers.Multiway_Trees A.18.10(53/3) +Delete_Directory in Ada.Directories A.16(8/2) +Delete_File in Ada.Directories A.16(11/2) +Delete_First + in Ada.Containers.Doubly_Linked_Lists A.18.3(25/2) + in Ada.Containers.Ordered_Maps A.18.6(26/2) + in Ada.Containers.Ordered_Sets A.18.9(25/2) + in Ada.Containers.Vectors A.18.2(52/2) +Delete_Last + in Ada.Containers.Doubly_Linked_Lists A.18.3(26/2) + in Ada.Containers.Ordered_Maps A.18.6(27/2) + in Ada.Containers.Ordered_Sets A.18.9(26/2) + in Ada.Containers.Vectors A.18.2(53/2) +Delete_Leaf + in Ada.Containers.Multiway_Trees A.18.10(35/3) +Delete_Subtree + in Ada.Containers.Multiway_Trees A.18.10(36/3) +Delete_Tree in Ada.Directories A.16(10/2) +Depth + in Ada.Containers.Multiway_Trees A.18.10(19/3) +Dequeue + in Ada.Containers.Bounded_Priority_Queues A.18.31(5/3) + in Ada.Containers.Bounded_Synchronized_Queues + +A.18.29(5/3) + + in Ada.Containers.Synchronized_Queue_Interfaces + +A.18.27(6/3) + +A.4.11(27/3), A.4.11(28/3) + + in Ada.Containers.Unbounded_Priority_Queues + + in Ada.Strings.UTF_Encoding.Wide_Strings A.4.11(34/3), + +A.18.30(5/3) + +A.4.11(35/3), A.4.11(36/3) + + in Ada.Containers.Unbounded_Synchronized_Queues + + in Ada.Strings.UTF_Encoding.Wide_Wide_Strings + +A.18.28(5/3) + +A.4.11(42/3), A.4.11(43/3), A.4.11(44/3) +Decrement in Interfaces.C.Pointers B.3.2(11/3) +Default_Modulus + in Ada.Containers.Indefinite_Holders A.18.21(10/3), + +A.18.23(10/3) + +Default_Subpool_for_Pool + in System.Storage_Pools.Subpools 13.11.4(13/3) +Delay_Until_And_Set_CPU + in System.Multiprocessors.Dispatching_Domains + +D.16.1(14/3) + +Delay_Until_And_Set_Deadline + in Ada.Dispatching.EDF D.2.6(9/2) +Delete + in Ada.Containers.Doubly_Linked_Lists A.18.3(24/2) + in Ada.Containers.Hashed_Maps A.18.5(25/2), A.18.5(26/2) + in Ada.Containers.Hashed_Sets A.18.8(24/2), A.18.8(25/2), + +A.18.8(55/2) + +Dequeue_Only_High_Priority + in Ada.Containers.Bounded_Priority_Queues A.18.31(6/3) + in Ada.Containers.Unbounded_Priority_Queues + +A.18.30(6/3) +Dereference_Error + in Interfaces.C.Strings B.3.1(12) +Descendant_Tag in Ada.Tags 3.9(7.1/2) +Detach_Handler in Ada.Interrupts C.3.2(9) +Determinant + in Ada.Numerics.Generic_Complex_Arrays G.3.2(46/2) + in Ada.Numerics.Generic_Real_Arrays G.3.1(24/2) +Difference + in Ada.Calendar.Arithmetic 9.6.1(12/2) + in Ada.Containers.Hashed_Sets A.18.8(32/2), A.18.8(33/2) + in Ada.Containers.Ordered_Sets A.18.9(33/2), A.18.9(34/2) +Divide in Ada.Decimal F.2(6/3) +Do_APC in System.RPC E.5(10) + +Q.3 Language-Defined Subprograms + +13 December 2012 852 + + Ada Reference Manual — 2012 Edition + +Do_RPC in System.RPC E.5(9) +Eigensystem + in Ada.Numerics.Generic_Complex_Arrays G.3.2(49/2) + in Ada.Numerics.Generic_Real_Arrays G.3.1(27/2) +Eigenvalues + in Ada.Numerics.Generic_Complex_Arrays G.3.2(48/2) + in Ada.Numerics.Generic_Real_Arrays G.3.1(26/2) +Element + in Ada.Containers.Doubly_Linked_Lists A.18.3(14/2) + in Ada.Containers.Hashed_Maps A.18.5(14/2), A.18.5(31/2) + in Ada.Containers.Hashed_Sets A.18.8(15/2), A.18.8(52/2) + in Ada.Containers.Indefinite_Holders A.18.18(12/3) + in Ada.Containers.Multiway_Trees A.18.10(24/3) + in Ada.Containers.Ordered_Maps A.18.6(13/2), + +A.18.6(39/2) + + in Ada.Containers.Ordered_Sets A.18.9(14/2), A.18.9(65/2) + in Ada.Containers.Vectors A.18.2(27/2), A.18.2(28/2) + in Ada.Strings.Bounded A.4.4(26) + in Ada.Strings.Unbounded A.4.5(20) +Encode + in Ada.Strings.UTF_Encoding.Strings A.4.11(23/3), + +A.4.11(24/3), A.4.11(25/3) + + in Ada.Strings.UTF_Encoding.Wide_Strings A.4.11(31/3), + +A.4.11(32/3), A.4.11(33/3) + + in Ada.Strings.UTF_Encoding.Wide_Wide_Strings + +Equivalent_Keys + in Ada.Containers.Hashed_Maps A.18.5(34/2), + +A.18.5(35/2), A.18.5(36/2) + + in Ada.Containers.Ordered_Maps A.18.6(3/2) + in Ada.Containers.Ordered_Sets A.18.9(63/2) +Equivalent_Sets + in Ada.Containers.Hashed_Sets A.18.8(8/2) + in Ada.Containers.Ordered_Sets A.18.9(9/2) +Establish_RPC_Receiver in System.RPC E.5(12) +Exception_Identity in Ada.Exceptions 11.4.1(5/2) +Exception_Information + in Ada.Exceptions 11.4.1(5/2) +Exception_Message in Ada.Exceptions 11.4.1(4/3) +Exception_Name in Ada.Exceptions 11.4.1(2/2), 11.4.1(5/2) +Exchange_Handler in Ada.Interrupts C.3.2(8) +Exclude + in Ada.Containers.Hashed_Maps A.18.5(24/2) + in Ada.Containers.Hashed_Sets A.18.8(23/2), A.18.8(54/2) + in Ada.Containers.Ordered_Maps A.18.6(23/2) + in Ada.Containers.Ordered_Sets A.18.9(22/2), A.18.9(67/2) +Exists + in Ada.Directories A.16(24/2) + in Ada.Environment_Variables A.17(5/2) +Exp + in Ada.Numerics.Generic_Complex_Elementary_Functions + +A.4.11(39/3), A.4.11(40/3), A.4.11(41/3) + +G.1.2(3) + +Encoding in Ada.Strings.UTF_Encoding A.4.11(13/3) +End_Of_File + in Ada.Direct_IO A.8.4(16) + in Ada.Sequential_IO A.8.1(13) + in Ada.Streams.Stream_IO A.12.1(12) + in Ada.Text_IO A.10.1(34) +End_Of_Line in Ada.Text_IO A.10.1(30) +End_Of_Page in Ada.Text_IO A.10.1(33) +End_Search in Ada.Directories A.16(33/2) +Enqueue + in Ada.Containers.Bounded_Priority_Queues A.18.31(5/3) + in Ada.Containers.Bounded_Synchronized_Queues + +A.18.29(5/3) + + in Ada.Containers.Synchronized_Queue_Interfaces + +A.18.27(5/3) + + in Ada.Containers.Unbounded_Priority_Queues + +A.18.30(5/3) + + in Ada.Containers.Unbounded_Synchronized_Queues + +A.18.28(5/3) +Environment_Task + in Ada.Task_Identification C.7.1(3/3) +Equal_Case_Insensitive + child of Ada.Strings A.4.10(2/3) + child of Ada.Strings.Bounded A.4.10(7/3) + child of Ada.Strings.Fixed A.4.10(5/3) + child of Ada.Strings.Unbounded A.4.10(10/3) +Equal_Subtree + in Ada.Containers.Multiway_Trees A.18.10(14/3) +Equivalent_Elements + in Ada.Containers.Hashed_Sets A.18.8(46/2), A.18.8(47/2), + +A.18.8(48/2) + + in Ada.Containers.Ordered_Sets A.18.9(3/2) + + in Ada.Numerics.Generic_Elementary_Functions A.5.1(4) +Expanded_Name in Ada.Tags 3.9(7/2) +Extension in Ada.Directories A.16(18/2) +External_Tag in Ada.Tags 3.9(7/2) +Finalize in Ada.Finalization 7.6(6/2), 7.6(8/2) +Find + in Ada.Containers.Doubly_Linked_Lists A.18.3(41/2) + in Ada.Containers.Hashed_Maps A.18.5(30/2) + in Ada.Containers.Hashed_Sets A.18.8(43/2), A.18.8(56/2) + in Ada.Containers.Multiway_Trees A.18.10(38/3) + in Ada.Containers.Ordered_Maps A.18.6(38/2) + in Ada.Containers.Ordered_Sets A.18.9(49/2), A.18.9(69/2) + in Ada.Containers.Vectors A.18.2(68/2) +Find_In_Subtree + in Ada.Containers.Multiway_Trees A.18.10(39/3) +Find_Index in Ada.Containers.Vectors A.18.2(67/2) +Find_Token + in Ada.Strings.Bounded A.4.4(50.1/3), A.4.4(51) + in Ada.Strings.Fixed A.4.3(15.1/3), A.4.3(16) + in Ada.Strings.Unbounded A.4.5(45.1/3), A.4.5(46) +First + in Ada.Containers.Doubly_Linked_Lists A.18.3(33/2) + in Ada.Containers.Hashed_Maps A.18.5(27/2) + in Ada.Containers.Hashed_Sets A.18.8(40/2) + in Ada.Containers.Ordered_Maps A.18.6(28/2) + in Ada.Containers.Ordered_Sets A.18.9(41/2) + in Ada.Containers.Vectors A.18.2(58/2) + in Ada.Iterator_Interfaces 5.5.1(3/3) +First_Child + in Ada.Containers.Multiway_Trees A.18.10(60/3) +First_Child_Element + in Ada.Containers.Multiway_Trees A.18.10(61/3) + +853 13 December 2012 + +Language-Defined Subprograms Q.3 + + Ada Reference Manual — 2012 Edition + +First_Element + in Ada.Containers.Doubly_Linked_Lists A.18.3(34/2) + in Ada.Containers.Ordered_Maps A.18.6(29/2) + in Ada.Containers.Ordered_Sets A.18.9(42/2) + in Ada.Containers.Vectors A.18.2(59/2) +First_Index in Ada.Containers.Vectors A.18.2(57/2) +First_Key + in Ada.Containers.Ordered_Maps A.18.6(30/2) +Floor + in Ada.Containers.Ordered_Maps A.18.6(40/2) + in Ada.Containers.Ordered_Sets A.18.9(50/2), A.18.9(70/2) +Flush + in Ada.Streams.Stream_IO A.12.1(25/1) + in Ada.Text_IO A.10.1(21/1) +Form + in Ada.Direct_IO A.8.4(9) + in Ada.Sequential_IO A.8.1(9) + in Ada.Streams.Stream_IO A.12.1(11) + in Ada.Text_IO A.10.1(12) +Free + in Ada.Strings.Unbounded A.4.5(7) + in Interfaces.C.Strings B.3.1(11) +Full_Name in Ada.Directories A.16(15/2), A.16(39/2) +Generic_Array_Sort + child of Ada.Containers A.18.26(3/2) +Generic_Constrained_Array_Sort + child of Ada.Containers A.18.26(7/2) +Generic_Sort + child of Ada.Containers A.18.26(9.2/3) +Get + in Ada.Text_IO A.10.1(41), A.10.1(47), A.10.1(54), + +A.10.1(55), A.10.1(59), A.10.1(60), A.10.1(65), A.10.1(67), +A.10.1(70), A.10.1(72), A.10.1(75), A.10.1(77), A.10.1(81), +A.10.1(83) + + in Ada.Text_IO.Complex_IO G.1.3(6), G.1.3(8) +Get_CPU + in Ada.Interrupts C.3.2(10.1/3) + in System.Multiprocessors.Dispatching_Domains + +D.16.1(13/3) + +Get_Deadline in Ada.Dispatching.EDF D.2.6(9/2) +Get_Dispatching_Domain + in System.Multiprocessors.Dispatching_Domains + +D.16.1(10/3) +Get_First_CPU + in System.Multiprocessors.Dispatching_Domains + +D.16.1(8/3) + +Get_Immediate in Ada.Text_IO A.10.1(44), A.10.1(45) +Get_Last_CPU + in System.Multiprocessors.Dispatching_Domains + +D.16.1(9/3) + +Get_Line + in Ada.Text_IO A.10.1(49), A.10.1(49.1/2) + in Ada.Text_IO.Bounded_IO A.10.11(8/2), A.10.11(9/2), + +A.10.11(10/2), A.10.11(11/2) + + in Ada.Text_IO.Unbounded_IO A.10.12(8/2), A.10.12(9/2), + +A.10.12(10/2), A.10.12(11/2) + +Get_Next_Entry in Ada.Directories A.16(35/2) +Get_Priority + in Ada.Dynamic_Priorities D.5.1(5) + +Has_Element + in Ada.Containers.Doubly_Linked_Lists A.18.3(9.1/3) + in Ada.Containers.Hashed_Maps A.18.5(6.1/3) + in Ada.Containers.Hashed_Sets A.18.8(6.1/3) + in Ada.Containers.Multiway_Trees A.18.10(12/3) + in Ada.Containers.Ordered_Maps A.18.6(7.1/3) + in Ada.Containers.Ordered_Sets A.18.9(7.1/3) + in Ada.Containers.Vectors A.18.2(11.1/3) +Hash + child of Ada.Strings A.4.9(2/3) + child of Ada.Strings.Bounded A.4.9(7/3) + child of Ada.Strings.Unbounded A.4.9(10/3) +Hash_Case_Insensitive + child of Ada.Strings A.4.9(11.2/3) + child of Ada.Strings.Bounded A.4.9(11.7/3) + child of Ada.Strings.Fixed A.4.9(11.5/3) + child of Ada.Strings.Unbounded A.4.9(11.10/3) +Head + in Ada.Strings.Bounded A.4.4(70), A.4.4(71) + in Ada.Strings.Fixed A.4.3(35), A.4.3(36) + in Ada.Strings.Unbounded A.4.5(65), A.4.5(66) +Hold in Ada.Asynchronous_Task_Control D.11(3/2) +Hour in Ada.Calendar.Formatting 9.6.1(24/2) +Im + in Ada.Numerics.Generic_Complex_Arrays G.3.2(7/2), + +G.3.2(27/2) + + in Ada.Numerics.Generic_Complex_Types G.1.1(6) +Image + in Ada.Calendar.Formatting 9.6.1(35/2), 9.6.1(37/2) + in Ada.Numerics.Discrete_Random A.5.2(26) + in Ada.Numerics.Float_Random A.5.2(14) + in Ada.Task_Identification C.7.1(3/3) + in Ada.Text_IO.Editing F.3.3(13) +Include + in Ada.Containers.Hashed_Maps A.18.5(22/2) + in Ada.Containers.Hashed_Sets A.18.8(21/2) + in Ada.Containers.Ordered_Maps A.18.6(21/2) + in Ada.Containers.Ordered_Sets A.18.9(20/2) +Increment in Interfaces.C.Pointers B.3.2(11/3) +Index + in Ada.Direct_IO A.8.4(15) + in Ada.Streams.Stream_IO A.12.1(23) + in Ada.Strings.Bounded A.4.4(43.1/2), A.4.4(43.2/2), + +A.4.4(44), A.4.4(45), A.4.4(45.1/2), A.4.4(46) + + in Ada.Strings.Fixed A.4.3(8.1/2), A.4.3(8.2/2), A.4.3(9), + +A.4.3(10), A.4.3(10.1/2), A.4.3(11) + + in Ada.Strings.Unbounded A.4.5(38.1/2), A.4.5(38.2/2), + +A.4.5(39), A.4.5(40), A.4.5(40.1/2), A.4.5(41) + +Index_Non_Blank + in Ada.Strings.Bounded A.4.4(46.1/2), A.4.4(47) + in Ada.Strings.Fixed A.4.3(11.1/2), A.4.3(12) + in Ada.Strings.Unbounded A.4.5(41.1/2), A.4.5(42) +Initial_Directory + in Ada.Directories.Hierarchical_File_Names A.16.1(12/3) +Initialize in Ada.Finalization 7.6(6/2), 7.6(8/2) +Insert + in Ada.Containers.Doubly_Linked_Lists A.18.3(19/2), + +A.18.3(20/2), A.18.3(21/2) + + in Ada.Containers.Hashed_Maps A.18.5(19/2), + +A.18.5(20/2), A.18.5(21/2) + +Q.3 Language-Defined Subprograms + +13 December 2012 854 + + Ada Reference Manual — 2012 Edition + + in Ada.Containers.Hashed_Sets A.18.8(19/2), A.18.8(20/2) + in Ada.Containers.Ordered_Maps A.18.6(18/2), + +A.18.6(19/2), A.18.6(20/2) + + in Ada.Containers.Ordered_Sets A.18.9(18/2), A.18.9(19/2) + in Ada.Containers.Vectors A.18.2(36/2), A.18.2(37/2), + +A.18.2(38/2), A.18.2(39/2), A.18.2(40/2), A.18.2(41/2), +A.18.2(42/2), A.18.2(43/2) + + in Ada.Strings.Bounded A.4.4(60), A.4.4(61) + in Ada.Strings.Fixed A.4.3(25), A.4.3(26) + in Ada.Strings.Unbounded A.4.5(55), A.4.5(56) +Insert_Child + in Ada.Containers.Multiway_Trees A.18.10(48/3), + +A.18.10(49/3), A.18.10(50/3) + +Insert_Space + in Ada.Containers.Vectors A.18.2(48/2), A.18.2(49/2) +Interface_Ancestor_Tags in Ada.Tags 3.9(7.4/2) +Internal_Tag in Ada.Tags 3.9(7/2) +Intersection + in Ada.Containers.Hashed_Sets A.18.8(29/2), A.18.8(30/2) + in Ada.Containers.Ordered_Sets A.18.9(30/2), A.18.9(31/2) +Inverse + in Ada.Numerics.Generic_Complex_Arrays G.3.2(46/2) + in Ada.Numerics.Generic_Real_Arrays G.3.1(24/2) +Is_A_Group_Member + in Ada.Execution_Time.Group_Budgets D.14.2(8/2) +Is_Abstract in Ada.Tags 3.9(7.5/3) +Is_Alphanumeric + in Ada.Characters.Handling A.3.2(4/3) + in Ada.Wide_Characters.Handling A.3.5(12/3) +Is_Attached in Ada.Interrupts C.3.2(5) +Is_Basic in Ada.Characters.Handling A.3.2(4/3) +Is_Callable + in Ada.Task_Identification C.7.1(4/3) +Is_Character + in Ada.Characters.Conversions A.3.4(3/2) +Is_Control + in Ada.Characters.Handling A.3.2(4/3) + in Ada.Wide_Characters.Handling A.3.5(5/3) +Is_Current_Directory_Name + in Ada.Directories.Hierarchical_File_Names A.16.1(7/3) +Is_Decimal_Digit + in Ada.Characters.Handling A.3.2(4/3) + in Ada.Wide_Characters.Handling A.3.5(10/3) +Is_Descendant_At_Same_Level + in Ada.Tags 3.9(7.1/2) +Is_Digit + in Ada.Characters.Handling A.3.2(4/3) + in Ada.Wide_Characters.Handling A.3.5(9/3) +Is_Empty + in Ada.Containers.Doubly_Linked_Lists A.18.3(12/2) + in Ada.Containers.Hashed_Maps A.18.5(11/2) + in Ada.Containers.Hashed_Sets A.18.8(13/2) + in Ada.Containers.Indefinite_Holders A.18.18(10/3) + in Ada.Containers.Multiway_Trees A.18.10(16/3) + in Ada.Containers.Ordered_Maps A.18.6(10/2) + in Ada.Containers.Ordered_Sets A.18.9(12/2) + in Ada.Containers.Vectors A.18.2(23/2) +Is_Full_Name + in Ada.Directories.Hierarchical_File_Names A.16.1(8/3) +Is_Graphic + + in Ada.Characters.Handling A.3.2(4/3) + in Ada.Wide_Characters.Handling A.3.5(19/3) +Is_Held + in Ada.Asynchronous_Task_Control D.11(3/2) +Is_Hexadecimal_Digit + in Ada.Characters.Handling A.3.2(4/3) + in Ada.Wide_Characters.Handling A.3.5(11/3) +Is_In + in Ada.Strings.Maps A.4.2(13) + in Ada.Strings.Wide_Maps A.4.7(13) + in Ada.Strings.Wide_Wide_Maps A.4.8(13/2) +Is_ISO_646 in Ada.Characters.Handling A.3.2(10) +Is_Leaf + in Ada.Containers.Multiway_Trees A.18.10(21/3) +Is_Letter + in Ada.Characters.Handling A.3.2(4/3) + in Ada.Wide_Characters.Handling A.3.5(6/3) +Is_Line_Terminator + in Ada.Characters.Handling A.3.2(4/3) + in Ada.Wide_Characters.Handling A.3.5(14/3) +Is_Lower + in Ada.Characters.Handling A.3.2(4/3) + in Ada.Wide_Characters.Handling A.3.5(7/3) +Is_Mark + in Ada.Characters.Handling A.3.2(4/3) + in Ada.Wide_Characters.Handling A.3.5(15/3) +Is_Member + in Ada.Execution_Time.Group_Budgets D.14.2(8/2) +Is_Nul_Terminated in Interfaces.C B.3(24), B.3(35), + +B.3(39.16/2), B.3(39.7/2) + +Is_Open + in Ada.Direct_IO A.8.4(10) + in Ada.Sequential_IO A.8.1(10) + in Ada.Streams.Stream_IO A.12.1(12) + in Ada.Text_IO A.10.1(13) +Is_Other_Format + in Ada.Characters.Handling A.3.2(4/3) + in Ada.Wide_Characters.Handling A.3.5(16/3) +Is_Parent_Directory_Name + in Ada.Directories.Hierarchical_File_Names A.16.1(6/3) +Is_Punctuation_Connector + in Ada.Characters.Handling A.3.2(4/3) + in Ada.Wide_Characters.Handling A.3.5(17/3) +Is_Relative_Name + in Ada.Directories.Hierarchical_File_Names A.16.1(9/3) +Is_Reserved in Ada.Interrupts C.3.2(4) +Is_Root + in Ada.Containers.Multiway_Trees A.18.10(20/3) +Is_Root_Directory_Name + in Ada.Directories.Hierarchical_File_Names A.16.1(5/3) +Is_Round_Robin + in Ada.Dispatching.Round_Robin D.2.5(4/2) +Is_Simple_Name + in Ada.Directories.Hierarchical_File_Names A.16.1(4/3) +Is_Sorted + in Ada.Containers.Doubly_Linked_Lists A.18.3(48/2) + in Ada.Containers.Vectors A.18.2(76/2) +Is_Space + in Ada.Characters.Handling A.3.2(4/3) + in Ada.Wide_Characters.Handling A.3.5(18/3) + +855 13 December 2012 + +Language-Defined Subprograms Q.3 + + Ada Reference Manual — 2012 Edition + +Is_Special + in Ada.Characters.Handling A.3.2(4/3) + in Ada.Wide_Characters.Handling A.3.5(13/3) +Is_String + in Ada.Characters.Conversions A.3.4(3/2) +Is_Subset + in Ada.Containers.Hashed_Sets A.18.8(39/2) + in Ada.Containers.Ordered_Sets A.18.9(40/2) + in Ada.Strings.Maps A.4.2(14) + in Ada.Strings.Wide_Maps A.4.7(14) + in Ada.Strings.Wide_Wide_Maps A.4.8(14/2) +Is_Terminated + in Ada.Task_Identification C.7.1(4/3) +Is_Upper + in Ada.Characters.Handling A.3.2(4/3) + in Ada.Wide_Characters.Handling A.3.5(8/3) +Is_Wide_Character + in Ada.Characters.Conversions A.3.4(3/2) +Is_Wide_String + in Ada.Characters.Conversions A.3.4(3/2) +Iterate + in Ada.Containers.Doubly_Linked_Lists A.18.3(45/2) + in Ada.Containers.Hashed_Maps A.18.5(37/2) + in Ada.Containers.Hashed_Sets A.18.8(49/2) + in Ada.Containers.Multiway_Trees A.18.10(42/3), + +A.18.10(44/3) + + in Ada.Containers.Ordered_Maps A.18.6(50/2) + in Ada.Containers.Ordered_Sets A.18.9(60/2) + in Ada.Containers.Vectors A.18.2(73/2) + in Ada.Environment_Variables A.17(8/3) +Iterate_Children + in Ada.Containers.Multiway_Trees A.18.10(68/3), + +A.18.10(70/3) + +Iterate_Subtree + in Ada.Containers.Multiway_Trees A.18.10(43/3), + +A.18.10(45/3) + +Key + in Ada.Containers.Hashed_Maps A.18.5(13/2) + in Ada.Containers.Hashed_Sets A.18.8(51/2) + in Ada.Containers.Ordered_Maps A.18.6(12/2) + in Ada.Containers.Ordered_Sets A.18.9(64/2) +Kind in Ada.Directories A.16(25/2), A.16(40/2) +Language in Ada.Locales A.19(6/3) +Last + in Ada.Containers.Doubly_Linked_Lists A.18.3(35/2) + in Ada.Containers.Ordered_Maps A.18.6(31/2) + in Ada.Containers.Ordered_Sets A.18.9(43/2) + in Ada.Containers.Vectors A.18.2(61/2) + in Ada.Iterator_Interfaces 5.5.1(4/3) +Last_Child + in Ada.Containers.Multiway_Trees A.18.10(62/3) +Last_Child_Element + in Ada.Containers.Multiway_Trees A.18.10(63/3) +Last_Element + in Ada.Containers.Doubly_Linked_Lists A.18.3(36/2) + in Ada.Containers.Ordered_Maps A.18.6(32/2) + in Ada.Containers.Ordered_Sets A.18.9(44/2) + in Ada.Containers.Vectors A.18.2(62/2) +Last_Index in Ada.Containers.Vectors A.18.2(60/2) + +Last_Key + in Ada.Containers.Ordered_Maps A.18.6(33/2) +Length + in Ada.Containers.Doubly_Linked_Lists A.18.3(11/2) + in Ada.Containers.Hashed_Maps A.18.5(10/2) + in Ada.Containers.Hashed_Sets A.18.8(12/2) + in Ada.Containers.Ordered_Maps A.18.6(9/2) + in Ada.Containers.Ordered_Sets A.18.9(11/2) + in Ada.Containers.Vectors A.18.2(21/2) + in Ada.Strings.Bounded A.4.4(9) + in Ada.Strings.Unbounded A.4.5(6) + in Ada.Text_IO.Editing F.3.3(11) + in Interfaces.COBOL B.4(34), B.4(39), B.4(44) +Less_Case_Insensitive + child of Ada.Strings A.4.10(13/3) + child of Ada.Strings.Bounded A.4.10(18/3) + child of Ada.Strings.Fixed A.4.10(16/3) + child of Ada.Strings.Unbounded A.4.10(21/3) +Line in Ada.Text_IO A.10.1(38) +Line_Length in Ada.Text_IO A.10.1(25) +Log + in Ada.Numerics.Generic_Complex_Elementary_Functions + +G.1.2(3) + + in Ada.Numerics.Generic_Elementary_Functions A.5.1(4) +Look_Ahead in Ada.Text_IO A.10.1(43) +Members + in Ada.Execution_Time.Group_Budgets D.14.2(8/2) +Merge + in Ada.Containers.Doubly_Linked_Lists A.18.3(50/2) + in Ada.Containers.Vectors A.18.2(78/2) +Microseconds in Ada.Real_Time D.8(14/2) +Milliseconds in Ada.Real_Time D.8(14/2) +Minute in Ada.Calendar.Formatting 9.6.1(25/2) +Minutes in Ada.Real_Time D.8(14/2) +Mode + in Ada.Direct_IO A.8.4(9) + in Ada.Sequential_IO A.8.1(9) + in Ada.Streams.Stream_IO A.12.1(11) + in Ada.Text_IO A.10.1(12) +Modification_Time in Ada.Directories A.16(27/2), A.16(42/2) +Modulus + in Ada.Numerics.Generic_Complex_Arrays G.3.2(10/2), + +G.3.2(30/2) + + in Ada.Numerics.Generic_Complex_Types G.1.1(9) +Month + in Ada.Calendar 9.6(13) + in Ada.Calendar.Formatting 9.6.1(22/2) +More_Entries in Ada.Directories A.16(34/2) +Move + in Ada.Containers.Doubly_Linked_Lists A.18.3(18/2) + in Ada.Containers.Hashed_Maps A.18.5(18/2) + in Ada.Containers.Hashed_Sets A.18.8(18/2) + in Ada.Containers.Indefinite_Holders A.18.18(22/3) + in Ada.Containers.Multiway_Trees A.18.10(34/3) + in Ada.Containers.Ordered_Maps A.18.6(17/2) + in Ada.Containers.Ordered_Sets A.18.9(17/2) + in Ada.Containers.Vectors A.18.2(35/2) + in Ada.Strings.Fixed A.4.3(7) +Name + in Ada.Direct_IO A.8.4(9) + +Q.3 Language-Defined Subprograms + +13 December 2012 856 + + in Ada.Sequential_IO A.8.1(9) + in Ada.Streams.Stream_IO A.12.1(11) + in Ada.Text_IO A.10.1(12) +Name_Case_Equivalence + in Ada.Directories A.16(20.2/3) +Nanoseconds in Ada.Real_Time D.8(14/2) +New_Char_Array + in Interfaces.C.Strings B.3.1(9) +New_Line in Ada.Text_IO A.10.1(28) +New_Page in Ada.Text_IO A.10.1(31) +New_String in Interfaces.C.Strings B.3.1(10) +Next + in Ada.Containers.Doubly_Linked_Lists A.18.3(37/2), + +A.18.3(39/2) + + in Ada.Containers.Hashed_Maps A.18.5(28/2), A.18.5(29/2) + in Ada.Containers.Hashed_Sets A.18.8(41/2), A.18.8(42/2) + in Ada.Containers.Ordered_Maps A.18.6(34/2), + +A.18.6(35/2) + + in Ada.Containers.Ordered_Sets A.18.9(45/2), A.18.9(46/2) + in Ada.Containers.Vectors A.18.2(63/2), A.18.2(64/2) + in Ada.Iterator_Interfaces 5.5.1(3/3) +Next_Sibling + in Ada.Containers.Multiway_Trees A.18.10(64/3), + +A.18.10(66/3) + +Node_Count + in Ada.Containers.Multiway_Trees A.18.10(17/3) +Null_Task_Id + in Ada.Task_Identification C.7.1(2/2) +Number_Of_CPUs + in System.Multiprocessors D.16(5/3) +Open + in Ada.Direct_IO A.8.4(7) + in Ada.Sequential_IO A.8.1(7) + in Ada.Streams.Stream_IO A.12.1(9) + in Ada.Text_IO A.10.1(10) +Overlap + in Ada.Containers.Hashed_Sets A.18.8(38/2) + in Ada.Containers.Ordered_Sets A.18.9(39/2) +Overwrite + in Ada.Strings.Bounded A.4.4(62), A.4.4(63) + in Ada.Strings.Fixed A.4.3(27), A.4.3(28) + in Ada.Strings.Unbounded A.4.5(57), A.4.5(58) +Page in Ada.Text_IO A.10.1(39) +Page_Length in Ada.Text_IO A.10.1(26) +Parent + in Ada.Containers.Multiway_Trees A.18.10(59/3) +Parent_Tag in Ada.Tags 3.9(7.2/2) +Peak_Use + in Ada.Containers.Bounded_Priority_Queues A.18.31(7/3) + in Ada.Containers.Bounded_Synchronized_Queues + +A.18.29(6/3) + + in Ada.Containers.Synchronized_Queue_Interfaces + +A.18.27(7/3) + + in Ada.Containers.Unbounded_Priority_Queues + +A.18.30(7/3) + +Ada Reference Manual — 2012 Edition + +Prepend + in Ada.Containers.Doubly_Linked_Lists A.18.3(22/2) + in Ada.Containers.Vectors A.18.2(44/2), A.18.2(45/2) +Prepend_Child + in Ada.Containers.Multiway_Trees A.18.10(51/3) +Previous + in Ada.Containers.Doubly_Linked_Lists A.18.3(38/2), + +A.18.3(40/2) + + in Ada.Containers.Ordered_Maps A.18.6(36/2), + +A.18.6(37/2) + + in Ada.Containers.Ordered_Sets A.18.9(47/2), A.18.9(48/2) + in Ada.Containers.Vectors A.18.2(65/2), A.18.2(66/2) + in Ada.Iterator_Interfaces 5.5.1(4/3) +Previous_Sibling + in Ada.Containers.Multiway_Trees A.18.10(65/3), + +A.18.10(67/3) + +Put + in Ada.Text_IO A.10.1(42), A.10.1(48), A.10.1(55), + +A.10.1(60), A.10.1(66), A.10.1(67), A.10.1(71), A.10.1(72), +A.10.1(76), A.10.1(77), A.10.1(82), A.10.1(83) + + in Ada.Text_IO.Bounded_IO A.10.11(4/2), A.10.11(5/2) + in Ada.Text_IO.Complex_IO G.1.3(7), G.1.3(8) + in Ada.Text_IO.Editing F.3.3(14), F.3.3(15), F.3.3(16) + in Ada.Text_IO.Unbounded_IO A.10.12(4/2), A.10.12(5/2) +Put_Line + in Ada.Text_IO A.10.1(50) + in Ada.Text_IO.Bounded_IO A.10.11(6/2), A.10.11(7/2) + in Ada.Text_IO.Unbounded_IO A.10.12(6/2), A.10.12(7/2) +Query_Element + in Ada.Containers.Doubly_Linked_Lists A.18.3(16/2) + in Ada.Containers.Hashed_Maps A.18.5(16/2) + in Ada.Containers.Hashed_Sets A.18.8(17/2) + in Ada.Containers.Indefinite_Holders A.18.18(14/3) + in Ada.Containers.Multiway_Trees A.18.10(26/3) + in Ada.Containers.Ordered_Maps A.18.6(15/2) + in Ada.Containers.Ordered_Sets A.18.9(16/2) + in Ada.Containers.Vectors A.18.2(31/2), A.18.2(32/2) +Raise_Exception in Ada.Exceptions 11.4.1(4/3) +Random + in Ada.Numerics.Discrete_Random A.5.2(20) + in Ada.Numerics.Float_Random A.5.2(8) +Re + in Ada.Numerics.Generic_Complex_Arrays G.3.2(7/2), + +G.3.2(27/2) + + in Ada.Numerics.Generic_Complex_Types G.1.1(6) +Read + in Ada.Direct_IO A.8.4(12) + in Ada.Sequential_IO A.8.1(12) + in Ada.Storage_IO A.9(6) + in Ada.Streams 13.13.1(5) + in Ada.Streams.Stream_IO A.12.1(15), A.12.1(16) + in System.RPC E.5(7) +Reference + in Ada.Containers.Doubly_Linked_Lists A.18.3(17.4/3) + in Ada.Containers.Hashed_Maps A.18.5(17.4/3), + + in Ada.Containers.Unbounded_Synchronized_Queues + +A.18.5(17.6/3) + +A.18.28(6/3) + +Pic_String in Ada.Text_IO.Editing F.3.3(7) +Pool_of_Subpool + in System.Storage_Pools.Subpools 13.11.4(9/3) + + in Ada.Containers.Indefinite_Holders A.18.18(19/3) + in Ada.Containers.Multiway_Trees A.18.10(31/3) + in Ada.Containers.Ordered_Maps A.18.6(16.4/3), + +A.18.6(16.6/3) + +857 13 December 2012 + +Language-Defined Subprograms Q.3 + + Ada Reference Manual — 2012 Edition + + in Ada.Containers.Vectors A.18.2(34.4/3), A.18.2(34.6/3) + in Ada.Interrupts C.3.2(10) + in Ada.Task_Attributes C.7.2(5) +Reference_Preserving_Key + in Ada.Containers.Hashed_Sets A.18.8(58.2/3), + +A.18.8(58.4/3) + + in Ada.Containers.Ordered_Sets A.18.9(73.2/3), + +A.18.9(73.4/3) + +Reinitialize in Ada.Task_Attributes C.7.2(6) +Relative_Name + in Ada.Directories.Hierarchical_File_Names A.16.1(13/3) +Remove_Task + in Ada.Execution_Time.Group_Budgets D.14.2(8/2) +Rename in Ada.Directories A.16(12/2) +Replace + in Ada.Containers.Hashed_Maps A.18.5(23/2) + in Ada.Containers.Hashed_Sets A.18.8(22/2), A.18.8(53/2) + in Ada.Containers.Ordered_Maps A.18.6(22/2) + in Ada.Containers.Ordered_Sets A.18.9(21/2), A.18.9(66/2) +Replace_Element + in Ada.Containers.Doubly_Linked_Lists A.18.3(15/2) + in Ada.Containers.Hashed_Maps A.18.5(15/2) + in Ada.Containers.Hashed_Sets A.18.8(16/2) + in Ada.Containers.Indefinite_Holders A.18.18(13/3) + in Ada.Containers.Multiway_Trees A.18.10(25/3) + in Ada.Containers.Ordered_Maps A.18.6(14/2) + in Ada.Containers.Ordered_Sets A.18.9(15/2) + in Ada.Containers.Vectors A.18.2(29/2), A.18.2(30/2) + in Ada.Strings.Bounded A.4.4(27) + in Ada.Strings.Unbounded A.4.5(21) +Replace_Slice + in Ada.Strings.Bounded A.4.4(58), A.4.4(59) + in Ada.Strings.Fixed A.4.3(23), A.4.3(24) + in Ada.Strings.Unbounded A.4.5(53), A.4.5(54) +Replenish + in Ada.Execution_Time.Group_Budgets D.14.2(9/2) +Replicate in Ada.Strings.Bounded A.4.4(78), A.4.4(79), + +A.4.4(80) + +Reraise_Occurrence in Ada.Exceptions 11.4.1(4/3) +Reserve_Capacity + in Ada.Containers.Hashed_Maps A.18.5(9/2) + in Ada.Containers.Hashed_Sets A.18.8(11/2) + in Ada.Containers.Vectors A.18.2(20/2) +Reset + in Ada.Direct_IO A.8.4(8) + in Ada.Numerics.Discrete_Random A.5.2(21), A.5.2(24) + in Ada.Numerics.Float_Random A.5.2(9), A.5.2(12) + in Ada.Sequential_IO A.8.1(8) + in Ada.Streams.Stream_IO A.12.1(10) + in Ada.Text_IO A.10.1(11) +Reverse_Elements + in Ada.Containers.Doubly_Linked_Lists A.18.3(27/2) + in Ada.Containers.Vectors A.18.2(54/2) +Reverse_Find + in Ada.Containers.Doubly_Linked_Lists A.18.3(42/2) + in Ada.Containers.Vectors A.18.2(70/2) +Reverse_Find_Index + in Ada.Containers.Vectors A.18.2(69/2) + +Reverse_Iterate + in Ada.Containers.Doubly_Linked_Lists A.18.3(46/2) + in Ada.Containers.Ordered_Maps A.18.6(51/2) + in Ada.Containers.Ordered_Sets A.18.9(61/2) + in Ada.Containers.Vectors A.18.2(74/2) +Reverse_Iterate_Children + in Ada.Containers.Multiway_Trees A.18.10(69/3) +Root in Ada.Containers.Multiway_Trees A.18.10(22/3) +Save + in Ada.Numerics.Discrete_Random A.5.2(24) + in Ada.Numerics.Float_Random A.5.2(12) +Save_Occurrence in Ada.Exceptions 11.4.1(6/2) +Second in Ada.Calendar.Formatting 9.6.1(26/2) +Seconds + in Ada.Calendar 9.6(13) + in Ada.Real_Time D.8(14/2) +Seconds_Of in Ada.Calendar.Formatting 9.6.1(28/2) +Set in Ada.Environment_Variables A.17(6/2) +Set_Bounded_String + in Ada.Strings.Bounded A.4.4(12.1/2) +Set_Col in Ada.Text_IO A.10.1(35) +Set_CPU + in System.Multiprocessors.Dispatching_Domains + +D.16.1(12/3) + +Set_Deadline in Ada.Dispatching.EDF D.2.6(9/2) +Set_Dependents_Fallback_Handler + in Ada.Task_Termination C.7.3(5/2) +Set_Directory in Ada.Directories A.16(6/2) +Set_Error in Ada.Text_IO A.10.1(15) +Set_Exit_Status in Ada.Command_Line A.15(9) +Set_False + in Ada.Synchronous_Task_Control D.10(4) +Set_Handler + in Ada.Execution_Time.Group_Budgets D.14.2(10/2) + in Ada.Execution_Time.Timers D.14.1(7/2) + in Ada.Real_Time.Timing_Events D.15(5/2) +Set_Im + in Ada.Numerics.Generic_Complex_Arrays G.3.2(8/2), + +G.3.2(28/2) + + in Ada.Numerics.Generic_Complex_Types G.1.1(7) +Set_Index + in Ada.Direct_IO A.8.4(14) + in Ada.Streams.Stream_IO A.12.1(22) +Set_Input in Ada.Text_IO A.10.1(15) +Set_Length in Ada.Containers.Vectors A.18.2(22/2) +Set_Line in Ada.Text_IO A.10.1(36) +Set_Line_Length in Ada.Text_IO A.10.1(23) +Set_Mode in Ada.Streams.Stream_IO A.12.1(24) +Set_Output in Ada.Text_IO A.10.1(15) +Set_Page_Length in Ada.Text_IO A.10.1(24) +Set_Pool_of_Subpool + in System.Storage_Pools.Subpools 13.11.4(10/3) +Set_Priority + in Ada.Dynamic_Priorities D.5.1(4) +Set_Quantum + in Ada.Dispatching.Round_Robin D.2.5(4/2) +Set_Re + in Ada.Numerics.Generic_Complex_Arrays G.3.2(8/2), + +G.3.2(28/2) + + in Ada.Numerics.Generic_Complex_Types G.1.1(7) + +Q.3 Language-Defined Subprograms + +13 December 2012 858 + + Ada Reference Manual — 2012 Edition + +Set_Specific_Handler + in Ada.Task_Termination C.7.3(6/2) +Set_True + in Ada.Synchronous_Task_Control D.10(4) +Set_Unbounded_String + in Ada.Strings.Unbounded A.4.5(11.1/2) +Set_Value in Ada.Task_Attributes C.7.2(6) +Simple_Name + in Ada.Directories A.16(16/2), A.16(38/2) + in Ada.Directories.Hierarchical_File_Names A.16.1(10/3) +Sin + in Ada.Numerics.Generic_Complex_Elementary_Functions + +G.1.2(4) + + in Ada.Numerics.Generic_Elementary_Functions A.5.1(5) +Sinh + in Ada.Numerics.Generic_Complex_Elementary_Functions + +G.1.2(6) + + in Ada.Numerics.Generic_Elementary_Functions A.5.1(7) +Size + in Ada.Direct_IO A.8.4(15) + in Ada.Directories A.16(26/2), A.16(41/2) + in Ada.Streams.Stream_IO A.12.1(23) +Skip_Line in Ada.Text_IO A.10.1(29) +Skip_Page in Ada.Text_IO A.10.1(32) +Slice + in Ada.Strings.Bounded A.4.4(28) + in Ada.Strings.Unbounded A.4.5(22) +Solve + in Ada.Numerics.Generic_Complex_Arrays G.3.2(46/2) + in Ada.Numerics.Generic_Real_Arrays G.3.1(24/2) +Sort + in Ada.Containers.Doubly_Linked_Lists A.18.3(49/2) + in Ada.Containers.Vectors A.18.2(77/2) +Specific_Handler + in Ada.Task_Termination C.7.3(6/2) +Splice + in Ada.Containers.Doubly_Linked_Lists A.18.3(30/2), + +A.18.3(31/2), A.18.3(32/2) + +Splice_Children + in Ada.Containers.Multiway_Trees A.18.10(57/3), + +A.18.10(58/3) + +Splice_Subtree + in Ada.Containers.Multiway_Trees A.18.10(55/3), + +A.18.10(56/3) + +Split + in Ada.Calendar 9.6(14) + in Ada.Calendar.Formatting 9.6.1(29/2), 9.6.1(32/2), + +9.6.1(33/2), 9.6.1(34/2) + + in Ada.Execution_Time D.14(8/2) + in Ada.Real_Time D.8(16) +Sqrt + in Ada.Numerics.Generic_Complex_Elementary_Functions + +G.1.2(3) + + in Ada.Numerics.Generic_Elementary_Functions A.5.1(4) +Standard_Error in Ada.Text_IO A.10.1(16), A.10.1(19) +Standard_Input in Ada.Text_IO A.10.1(16), A.10.1(19) +Standard_Output in Ada.Text_IO A.10.1(16), A.10.1(19) +Start_Search in Ada.Directories A.16(32/2) +Storage_Size + in System.Storage_Pools 13.11(9) + + in System.Storage_Pools.Subpools 13.11.4(16/3) +Stream + in Ada.Streams.Stream_IO A.12.1(13) + in Ada.Text_IO.Text_Streams A.12.2(4) + in Ada.Wide_Text_IO.Text_Streams A.12.3(4) + in Ada.Wide_Wide_Text_IO.Text_Streams A.12.4(4/2) +Strlen in Interfaces.C.Strings B.3.1(17) +Sub_Second in Ada.Calendar.Formatting 9.6.1(27/2) +Subtree_Node_Count + in Ada.Containers.Multiway_Trees A.18.10(18/3) +Supported + in Ada.Execution_Time.Interrupts D.14.3(3/3) +Suspend_Until_True + in Ada.Synchronous_Task_Control D.10(4) +Suspend_Until_True_And_Set_Deadline + in Ada.Synchronous_Task_Control.EDF D.10(5.2/3) +Swap + in Ada.Containers.Doubly_Linked_Lists A.18.3(28/2) + in Ada.Containers.Multiway_Trees A.18.10(37/3) + in Ada.Containers.Vectors A.18.2(55/2), A.18.2(56/2) +Swap_Links + in Ada.Containers.Doubly_Linked_Lists A.18.3(29/2) +Symmetric_Difference + in Ada.Containers.Hashed_Sets A.18.8(35/2), A.18.8(36/2) + in Ada.Containers.Ordered_Sets A.18.9(36/2), A.18.9(37/2) +Tail + in Ada.Strings.Bounded A.4.4(72), A.4.4(73) + in Ada.Strings.Fixed A.4.3(37), A.4.3(38) + in Ada.Strings.Unbounded A.4.5(67), A.4.5(68) +Tan + in Ada.Numerics.Generic_Complex_Elementary_Functions + +G.1.2(4) + + in Ada.Numerics.Generic_Elementary_Functions A.5.1(5) +Tanh + in Ada.Numerics.Generic_Complex_Elementary_Functions + +G.1.2(6) + + in Ada.Numerics.Generic_Elementary_Functions A.5.1(7) +Time_Of + in Ada.Calendar 9.6(15) + in Ada.Calendar.Formatting 9.6.1(30/2), 9.6.1(31/2) + in Ada.Execution_Time D.14(9/2) + in Ada.Real_Time D.8(16) +Time_Of_Event + in Ada.Real_Time.Timing_Events D.15(6/2) +Time_Remaining + in Ada.Execution_Time.Timers D.14.1(8/2) +To_Ada + in Interfaces.C B.3(22), B.3(26), B.3(28), B.3(32), B.3(37), + +B.3(39), B.3(39.10/2), B.3(39.13/2), B.3(39.17/2), +B.3(39.19/2), B.3(39.4/2), B.3(39.8/2) + in Interfaces.COBOL B.4(17), B.4(19) + in Interfaces.Fortran B.5(13), B.5(14), B.5(16) +To_Address + in System.Address_To_Access_Conversions 13.7.2(3/3) + in System.Storage_Elements 13.7.1(10/3) +To_Basic in Ada.Characters.Handling A.3.2(6), A.3.2(7) +To_Binary in Interfaces.COBOL B.4(45), B.4(48) +To_Bounded_String + in Ada.Strings.Bounded A.4.4(11) + +859 13 December 2012 + +Language-Defined Subprograms Q.3 + + Ada Reference Manual — 2012 Edition + +To_C in Interfaces.C B.3(21), B.3(25), B.3(27), B.3(32), + +B.3(36), B.3(38), B.3(39.13/2), B.3(39.16/2), B.3(39.18/2), +B.3(39.4/2), B.3(39.7/2), B.3(39.9/2) + +To_Character + in Ada.Characters.Conversions A.3.4(5/2) +To_Chars_Ptr in Interfaces.C.Strings B.3.1(8) +To_COBOL in Interfaces.COBOL B.4(17), B.4(18) +To_Cursor in Ada.Containers.Vectors A.18.2(25/2) +To_Decimal in Interfaces.COBOL B.4(35), B.4(40), B.4(44), + +B.4(47) + +To_Display in Interfaces.COBOL B.4(36) +To_Domain + in Ada.Strings.Maps A.4.2(24) + in Ada.Strings.Wide_Maps A.4.7(24) + in Ada.Strings.Wide_Wide_Maps A.4.8(24/2) +To_Duration in Ada.Real_Time D.8(13) +To_Fortran in Interfaces.Fortran B.5(13), B.5(14), B.5(15) +To_Holder + in Ada.Containers.Indefinite_Holders A.18.18(9/3) +To_Index in Ada.Containers.Vectors A.18.2(26/2) +To_Integer in System.Storage_Elements 13.7.1(10/3) +To_ISO_646 in Ada.Characters.Handling A.3.2(11), A.3.2(12) +To_Long_Binary in Interfaces.COBOL B.4(48) +To_Lower + in Ada.Characters.Handling A.3.2(6), A.3.2(7) + in Ada.Wide_Characters.Handling A.3.5(20/3), A.3.5(21/3) +To_Mapping + in Ada.Strings.Maps A.4.2(23) + in Ada.Strings.Wide_Maps A.4.7(23) + in Ada.Strings.Wide_Wide_Maps A.4.8(23/2) +To_Packed in Interfaces.COBOL B.4(41) +To_Picture in Ada.Text_IO.Editing F.3.3(6) +To_Pointer + in System.Address_To_Access_Conversions 13.7.2(3/3) +To_Range + in Ada.Strings.Maps A.4.2(24) + in Ada.Strings.Wide_Maps A.4.7(25) + in Ada.Strings.Wide_Wide_Maps A.4.8(25/2) +To_Ranges + in Ada.Strings.Maps A.4.2(10) + in Ada.Strings.Wide_Maps A.4.7(10) + in Ada.Strings.Wide_Wide_Maps A.4.8(10/2) +To_Sequence + in Ada.Strings.Maps A.4.2(19) + in Ada.Strings.Wide_Maps A.4.7(19) + in Ada.Strings.Wide_Wide_Maps A.4.8(19/2) +To_Set + in Ada.Containers.Hashed_Sets A.18.8(9/2) + in Ada.Containers.Ordered_Sets A.18.9(10/2) + in Ada.Strings.Maps A.4.2(8), A.4.2(9), A.4.2(17), + +A.4.2(18) + + in Ada.Strings.Wide_Maps A.4.7(8), A.4.7(9), A.4.7(17), + +A.4.7(18) + + in Ada.Strings.Wide_Wide_Maps A.4.8(8/2), A.4.8(9/2), + +A.4.8(17/2), A.4.8(18/2) + +To_String + in Ada.Characters.Conversions A.3.4(5/2) + in Ada.Strings.Bounded A.4.4(12) + in Ada.Strings.Unbounded A.4.5(11) +To_Time_Span in Ada.Real_Time D.8(13) + +A.4.4(56) + +A.4.3(21) + +A.4.5(51) + +To_Unbounded_String + in Ada.Strings.Unbounded A.4.5(9), A.4.5(10) +To_Upper + in Ada.Characters.Handling A.3.2(6), A.3.2(7) + in Ada.Wide_Characters.Handling A.3.5(20/3), A.3.5(21/3) +To_Vector in Ada.Containers.Vectors A.18.2(13/2), + +A.18.2(14/2) +To_Wide_Character + in Ada.Characters.Conversions A.3.4(4/2), A.3.4(5/2) +To_Wide_String + in Ada.Characters.Conversions A.3.4(4/2), A.3.4(5/2) +To_Wide_Wide_Character + in Ada.Characters.Conversions A.3.4(4/2) +To_Wide_Wide_String + in Ada.Characters.Conversions A.3.4(4/2) +Translate + in Ada.Strings.Bounded A.4.4(53), A.4.4(54), A.4.4(55), + + in Ada.Strings.Fixed A.4.3(18), A.4.3(19), A.4.3(20), + + in Ada.Strings.Unbounded A.4.5(48), A.4.5(49), A.4.5(50), + +Transpose + in Ada.Numerics.Generic_Complex_Arrays G.3.2(34/2) + in Ada.Numerics.Generic_Real_Arrays G.3.1(17/2) +Trim + in Ada.Strings.Bounded A.4.4(67), A.4.4(68), A.4.4(69) + in Ada.Strings.Fixed A.4.3(31), A.4.3(32), A.4.3(33), + +A.4.3(34) + + in Ada.Strings.Unbounded A.4.5(61), A.4.5(62), A.4.5(63), + +A.4.5(64) +Unbounded_Slice + in Ada.Strings.Unbounded A.4.5(22.1/2), A.4.5(22.2/2) +Unchecked_Conversion + child of Ada 13.9(3/3) +Unchecked_Deallocation + child of Ada 13.11.2(3/3) +Union + in Ada.Containers.Hashed_Sets A.18.8(26/2), A.18.8(27/2) + in Ada.Containers.Ordered_Sets A.18.9(27/2), A.18.9(28/2) +Unit_Matrix + in Ada.Numerics.Generic_Complex_Arrays G.3.2(51/2) + in Ada.Numerics.Generic_Real_Arrays G.3.1(29/2) +Unit_Vector + in Ada.Numerics.Generic_Complex_Arrays G.3.2(24/2) + in Ada.Numerics.Generic_Real_Arrays G.3.1(14/2) +Update in Interfaces.C.Strings B.3.1(18), B.3.1(19) +Update_Element + in Ada.Containers.Doubly_Linked_Lists A.18.3(17/2) + in Ada.Containers.Hashed_Maps A.18.5(17/2) + in Ada.Containers.Indefinite_Holders A.18.18(15/3) + in Ada.Containers.Multiway_Trees A.18.10(27/3) + in Ada.Containers.Ordered_Maps A.18.6(16/2) + in Ada.Containers.Vectors A.18.2(33/2), A.18.2(34/2) +Update_Element_Preserving_Key + in Ada.Containers.Hashed_Sets A.18.8(58/2) + in Ada.Containers.Ordered_Sets A.18.9(73/2) +Update_Error in Interfaces.C.Strings B.3.1(20) +UTC_Time_Offset + in Ada.Calendar.Time_Zones 9.6.1(6/2) + +Q.3 Language-Defined Subprograms + +13 December 2012 860 + + Valid + in Ada.Text_IO.Editing F.3.3(5), F.3.3(12) + in Interfaces.COBOL B.4(33), B.4(38), B.4(43) +Value + in Ada.Calendar.Formatting 9.6.1(36/2), 9.6.1(38/2) + in Ada.Environment_Variables A.17(4.1/3), A.17(4/2) + in Ada.Numerics.Discrete_Random A.5.2(26) + in Ada.Numerics.Float_Random A.5.2(14) + in Ada.Strings.Maps A.4.2(21) + in Ada.Strings.Wide_Maps A.4.7(21) + in Ada.Strings.Wide_Wide_Maps A.4.8(21/2) + in Ada.Task_Attributes C.7.2(4) + in Interfaces.C.Pointers B.3.2(6), B.3.2(7) + in Interfaces.C.Strings B.3.1(13), B.3.1(14), B.3.1(15), + +B.3.1(16) +Virtual_Length + in Interfaces.C.Pointers B.3.2(13) +Wait_For_Release + in Ada.Synchronous_Barriers D.10.1(6/3) +Wide_Equal_Case_Insensitive + child of Ada.Strings.Wide_Bounded A.4.7(1/3) + child of Ada.Strings.Wide_Fixed A.4.7(1/3) + child of Ada.Strings.Wide_Unbounded A.4.7(1/3) +Wide_Hash + child of Ada.Strings.Wide_Bounded A.4.7(1/3) + child of Ada.Strings.Wide_Fixed A.4.7(1/3) + child of Ada.Strings.Wide_Unbounded A.4.7(1/3) +Wide_Hash_Case_Insensitive + child of Ada.Strings.Wide_Bounded A.4.7(1/3) + child of Ada.Strings.Wide_Fixed A.4.7(1/3) + child of Ada.Strings.Wide_Unbounded A.4.7(1/3) +Wide_Exception_Name in Ada.Exceptions 11.4.1(2/2), + +11.4.1(5/2) + +Ada Reference Manual — 2012 Edition + +Wide_Expanded_Name in Ada.Tags 3.9(7/2) +Wide_Wide_Equal_Case_Insensitive + child of Ada.Strings.Wide_Wide_Bounded A.4.8(1/3) + child of Ada.Strings.Wide_Wide_Fixed A.4.8(1/3) + child of Ada.Strings.Wide_Wide_Unbounded A.4.8(1/3) +Wide_Wide_Hash + child of Ada.Strings.Wide_Wide_Bounded A.4.8(1/3) + child of Ada.Strings.Wide_Wide_Fixed A.4.8(1/3) + child of Ada.Strings.Wide_Wide_Unbounded A.4.8(1/3) +Wide_Wide_Hash_Case_Insensitive + child of Ada.Strings.Wide_Wide_Bounded A.4.8(1/3) + child of Ada.Strings.Wide_Wide_Fixed A.4.8(1/3) + child of Ada.Strings.Wide_Wide_Unbounded A.4.8(1/3) +Wide_Wide_Exception_Name + in Ada.Exceptions 11.4.1(2/2), 11.4.1(5/2) +Wide_Wide_Expanded_Name in Ada.Tags 3.9(7/2) +Write + in Ada.Direct_IO A.8.4(13) + in Ada.Sequential_IO A.8.1(12) + in Ada.Storage_IO A.9(7) + in Ada.Streams 13.13.1(6) + in Ada.Streams.Stream_IO A.12.1(18), A.12.1(19) + in System.RPC E.5(8) +Year + in Ada.Calendar 9.6(13) + in Ada.Calendar.Formatting 9.6.1(21/2) +Yield in Ada.Dispatching D.2.1(1.3/3) +Yield_To_Higher + in Ada.Dispatching.Non_Preemptive D.2.4(2.2/3) +Yield_To_Same_Or_Higher + in Ada.Dispatching.Non_Preemptive D.2.4(2.2/3) + +Q.4 Language-Defined Exceptions + +This subclause lists all language-defined exceptions. + +1/3 + +Argument_Error + in Ada.Numerics A.5(3/2) +Assertion_Error + in Ada.Assertions 11.4.2(13/2) +Capacity_Error + in Ada.Containers A.18.1(5.1/3) +Communication_Error + in System.RPC E.5(5) +Constraint_Error + in Standard A.1(46) +Conversion_Error + in Interfaces.COBOL B.4(30) +Data_Error + in Ada.Direct_IO A.8.4(18) + in Ada.IO_Exceptions A.13(4) + in Ada.Sequential_IO A.8.1(15) + in Ada.Storage_IO A.9(9) + in Ada.Streams.Stream_IO A.12.1(26) + + in Ada.Text_IO A.10.1(85) +Device_Error + in Ada.Direct_IO A.8.4(18) + in Ada.Directories A.16(43/2) + in Ada.IO_Exceptions A.13(4) + in Ada.Sequential_IO A.8.1(15) + in Ada.Streams.Stream_IO A.12.1(26) + in Ada.Text_IO A.10.1(85) +Dispatching_Domain_Error + in System.Multiprocessors.Dispatching_Domains + +D.16.1(4/3) + +Dispatching_Policy_Error + in Ada.Dispatching D.2.1(1.4/3) +Encoding_Error + in Ada.Strings.UTF_Encoding A.4.11(8/3) +End_Error + in Ada.Direct_IO A.8.4(18) + in Ada.IO_Exceptions A.13(4) + +861 13 December 2012 + +Language-Defined Subprograms Q.3 + + + Ada Reference Manual — 2012 Edition + + in Ada.Sequential_IO A.8.1(15) + in Ada.Streams.Stream_IO A.12.1(26) + in Ada.Text_IO A.10.1(85) +Group_Budget_Error + in Ada.Execution_Time.Group_Budgets D.14.2(11/2) +Index_Error + in Ada.Strings A.4.1(5) +Layout_Error + in Ada.IO_Exceptions A.13(4) + in Ada.Text_IO A.10.1(85) +Length_Error + in Ada.Strings A.4.1(5) +Mode_Error + in Ada.Direct_IO A.8.4(18) + in Ada.IO_Exceptions A.13(4) + in Ada.Sequential_IO A.8.1(15) + in Ada.Streams.Stream_IO A.12.1(26) + in Ada.Text_IO A.10.1(85) +Name_Error + in Ada.Direct_IO A.8.4(18) + in Ada.Directories A.16(43/2) + in Ada.IO_Exceptions A.13(4) + in Ada.Sequential_IO A.8.1(15) + in Ada.Streams.Stream_IO A.12.1(26) + in Ada.Text_IO A.10.1(85) +Pattern_Error + in Ada.Strings A.4.1(5) +Picture_Error + in Ada.Text_IO.Editing F.3.3(9) +Pointer_Error + in Interfaces.C.Pointers B.3.2(8) + +Program_Error + in Standard A.1(46) +Status_Error + in Ada.Direct_IO A.8.4(18) + in Ada.Directories A.16(43/2) + in Ada.IO_Exceptions A.13(4) + in Ada.Sequential_IO A.8.1(15) + in Ada.Streams.Stream_IO A.12.1(26) + in Ada.Text_IO A.10.1(85) +Storage_Error + in Standard A.1(46) +Tag_Error + in Ada.Tags 3.9(8) +Tasking_Error + in Standard A.1(46) +Terminator_Error + in Interfaces.C B.3(40) +Time_Error + in Ada.Calendar 9.6(18) +Timer_Resource_Error + in Ada.Execution_Time.Timers D.14.1(9/2) +Translation_Error + in Ada.Strings A.4.1(5) +Unknown_Zone_Error + in Ada.Calendar.Time_Zones 9.6.1(5/2) +Use_Error + in Ada.Direct_IO A.8.4(18) + in Ada.Directories A.16(43/2) + in Ada.IO_Exceptions A.13(4) + in Ada.Sequential_IO A.8.1(15) + in Ada.Streams.Stream_IO A.12.1(26) + in Ada.Text_IO A.10.1(85) + +Q.5 Language-Defined Objects + +1/3 + +This subclause lists all language-defined constants, variables, named numbers, and enumeration literals. + +ACK in Ada.Characters.Latin_1 A.3.3(5) +Acute in Ada.Characters.Latin_1 A.3.3(22) +Ada_To_COBOL in Interfaces.COBOL B.4(14) +Alphanumeric_Set + in Ada.Strings.Maps.Constants A.4.6(4) +Ampersand in Ada.Characters.Latin_1 A.3.3(8) +APC in Ada.Characters.Latin_1 A.3.3(19) +Apostrophe in Ada.Characters.Latin_1 A.3.3(8) +Asterisk in Ada.Characters.Latin_1 A.3.3(8) +Basic_Map + in Ada.Strings.Maps.Constants A.4.6(5) +Basic_Set + in Ada.Strings.Maps.Constants A.4.6(4) +BEL in Ada.Characters.Latin_1 A.3.3(5) +BOM_16 in Ada.Strings.UTF_Encoding A.4.11(12/3) +BOM_16BE in Ada.Strings.UTF_Encoding A.4.11(10/3) +BOM_16LE in Ada.Strings.UTF_Encoding A.4.11(11/3) +BOM_8 in Ada.Strings.UTF_Encoding A.4.11(9/3) +BPH in Ada.Characters.Latin_1 A.3.3(17) + +Broken_Bar in Ada.Characters.Latin_1 A.3.3(21/3) +BS in Ada.Characters.Latin_1 A.3.3(5) +Buffer_Size in Ada.Storage_IO A.9(4) +CAN in Ada.Characters.Latin_1 A.3.3(6) +CCH in Ada.Characters.Latin_1 A.3.3(18) +Cedilla in Ada.Characters.Latin_1 A.3.3(22) +Cent_Sign in Ada.Characters.Latin_1 A.3.3(21/3) +char16_nul in Interfaces.C B.3(39.3/2) +char32_nul in Interfaces.C B.3(39.12/2) +CHAR_BIT in Interfaces.C B.3(6) +Character_Set + in Ada.Strings.Wide_Maps A.4.7(46/2) + in Ada.Strings.Wide_Maps.Wide_Constants A.4.8(48/2) +Circumflex in Ada.Characters.Latin_1 A.3.3(12) +COBOL_To_Ada in Interfaces.COBOL B.4(15) +Colon in Ada.Characters.Latin_1 A.3.3(10) +Comma in Ada.Characters.Latin_1 A.3.3(8) +Commercial_At + in Ada.Characters.Latin_1 A.3.3(10) + +Q.4 Language-Defined Exceptions + +13 December 2012 862 + + + Ada Reference Manual — 2012 Edition + +Control_Set + in Ada.Strings.Maps.Constants A.4.6(4) +Copyright_Sign + in Ada.Characters.Latin_1 A.3.3(21/3) +Country_Unknown in Ada.Locales A.19(5/3) +CPU_Tick in Ada.Execution_Time D.14(4/2) +CPU_Time_First in Ada.Execution_Time D.14(4/2) +CPU_Time_Last in Ada.Execution_Time D.14(4/2) +CPU_Time_Unit in Ada.Execution_Time D.14(4/2) +CR in Ada.Characters.Latin_1 A.3.3(5) +CSI in Ada.Characters.Latin_1 A.3.3(19) +Currency_Sign + in Ada.Characters.Latin_1 A.3.3(21/3) +DC1 in Ada.Characters.Latin_1 A.3.3(6) +DC2 in Ada.Characters.Latin_1 A.3.3(6) +DC3 in Ada.Characters.Latin_1 A.3.3(6) +DC4 in Ada.Characters.Latin_1 A.3.3(6) +DCS in Ada.Characters.Latin_1 A.3.3(18) +Decimal_Digit_Set + in Ada.Strings.Maps.Constants A.4.6(4) +Default_Aft + in Ada.Text_IO A.10.1(64), A.10.1(69), A.10.1(74) + in Ada.Text_IO.Complex_IO G.1.3(5) +Default_Base in Ada.Text_IO A.10.1(53), A.10.1(58) +Default_Bit_Order in System 13.7(15/2) +Default_Currency + in Ada.Text_IO.Editing F.3.3(10) +Default_Deadline + in Ada.Dispatching.EDF D.2.6(9/2) +Default_Exp + in Ada.Text_IO A.10.1(64), A.10.1(69), A.10.1(74) + in Ada.Text_IO.Complex_IO G.1.3(5) +Default_Fill in Ada.Text_IO.Editing F.3.3(10) +Default_Fore + in Ada.Text_IO A.10.1(64), A.10.1(69), A.10.1(74) + in Ada.Text_IO.Complex_IO G.1.3(5) +Default_Priority in System 13.7(17) +Default_Quantum + in Ada.Dispatching.Round_Robin D.2.5(4/2) +Default_Radix_Mark + in Ada.Text_IO.Editing F.3.3(10) +Default_Separator + in Ada.Text_IO.Editing F.3.3(10) +Default_Setting in Ada.Text_IO A.10.1(80) +Default_Width in Ada.Text_IO A.10.1(53), A.10.1(58), + +A.10.1(80) + +Degree_Sign in Ada.Characters.Latin_1 A.3.3(22) +DEL in Ada.Characters.Latin_1 A.3.3(14) +Diaeresis in Ada.Characters.Latin_1 A.3.3(21/3) +Division_Sign + in Ada.Characters.Latin_1 A.3.3(26) +DLE in Ada.Characters.Latin_1 A.3.3(6) +Dollar_Sign in Ada.Characters.Latin_1 A.3.3(8) +e in Ada.Numerics A.5(3/2) +EM in Ada.Characters.Latin_1 A.3.3(6) +Empty_Holder + in Ada.Containers.Indefinite_Holders A.18.18(7/3) +Empty_List + in Ada.Containers.Doubly_Linked_Lists A.18.3(8/2) + +Empty_Map + in Ada.Containers.Hashed_Maps A.18.5(5/2) + in Ada.Containers.Ordered_Maps A.18.6(6/2) +Empty_Set + in Ada.Containers.Hashed_Sets A.18.8(5/2) + in Ada.Containers.Ordered_Sets A.18.9(6/2) +Empty_Tree + in Ada.Containers.Multiway_Trees A.18.10(10/3) +Empty_Vector + in Ada.Containers.Vectors A.18.2(10/2) +ENQ in Ada.Characters.Latin_1 A.3.3(5) +EOT in Ada.Characters.Latin_1 A.3.3(5) +EPA in Ada.Characters.Latin_1 A.3.3(18) +Equals_Sign in Ada.Characters.Latin_1 A.3.3(10) +ESA in Ada.Characters.Latin_1 A.3.3(17) +ESC in Ada.Characters.Latin_1 A.3.3(6) +ETB in Ada.Characters.Latin_1 A.3.3(6) +ETX in Ada.Characters.Latin_1 A.3.3(5) +Exclamation in Ada.Characters.Latin_1 A.3.3(8) +Failure in Ada.Command_Line A.15(8) +Feminine_Ordinal_Indicator + in Ada.Characters.Latin_1 A.3.3(21/3) +FF in Ada.Characters.Latin_1 A.3.3(5) +Fine_Delta in System 13.7(9) +Fraction_One_Half + in Ada.Characters.Latin_1 A.3.3(22) +Fraction_One_Quarter + in Ada.Characters.Latin_1 A.3.3(22) +Fraction_Three_Quarters + in Ada.Characters.Latin_1 A.3.3(22) +Friday in Ada.Calendar.Formatting 9.6.1(17/2) +FS in Ada.Characters.Latin_1 A.3.3(6) +Full_Stop in Ada.Characters.Latin_1 A.3.3(8) +Graphic_Set + in Ada.Strings.Maps.Constants A.4.6(4) +Grave in Ada.Characters.Latin_1 A.3.3(13) +Greater_Than_Sign + in Ada.Characters.Latin_1 A.3.3(10) +GS in Ada.Characters.Latin_1 A.3.3(6) +Hexadecimal_Digit_Set + in Ada.Strings.Maps.Constants A.4.6(4) +High_Order_First + in Interfaces.COBOL B.4(25) + in System 13.7(15/2) +HT in Ada.Characters.Latin_1 A.3.3(5) +HTJ in Ada.Characters.Latin_1 A.3.3(17) +HTS in Ada.Characters.Latin_1 A.3.3(17) +Hyphen in Ada.Characters.Latin_1 A.3.3(8) +i + in Ada.Numerics.Generic_Complex_Types G.1.1(5) + in Interfaces.Fortran B.5(10) +Identity + in Ada.Strings.Maps A.4.2(22) + in Ada.Strings.Wide_Maps A.4.7(22) + in Ada.Strings.Wide_Wide_Maps A.4.8(22/2) +Interrupt_Clocks_Supported + in Ada.Execution_Time D.14(9.1/3) +Inverted_Exclamation + in Ada.Characters.Latin_1 A.3.3(21/3) + +863 13 December 2012 + +Language-Defined Objects Q.5 + + Ada Reference Manual — 2012 Edition + +Inverted_Question + in Ada.Characters.Latin_1 A.3.3(22) +IS1 in Ada.Characters.Latin_1 A.3.3(16) +IS2 in Ada.Characters.Latin_1 A.3.3(16) +IS3 in Ada.Characters.Latin_1 A.3.3(16) +IS4 in Ada.Characters.Latin_1 A.3.3(16) +ISO_646_Set + in Ada.Strings.Maps.Constants A.4.6(4) +j + in Ada.Numerics.Generic_Complex_Types G.1.1(5) + in Interfaces.Fortran B.5(10) +Language_Unknown in Ada.Locales A.19(5/3) +LC_A in Ada.Characters.Latin_1 A.3.3(13) +LC_A_Acute in Ada.Characters.Latin_1 A.3.3(25) +LC_A_Circumflex + in Ada.Characters.Latin_1 A.3.3(25) +LC_A_Diaeresis + in Ada.Characters.Latin_1 A.3.3(25) +LC_A_Grave in Ada.Characters.Latin_1 A.3.3(25) +LC_A_Ring in Ada.Characters.Latin_1 A.3.3(25) +LC_A_Tilde in Ada.Characters.Latin_1 A.3.3(25) +LC_AE_Diphthong + in Ada.Characters.Latin_1 A.3.3(25) +LC_B in Ada.Characters.Latin_1 A.3.3(13) +LC_C in Ada.Characters.Latin_1 A.3.3(13) +LC_C_Cedilla + in Ada.Characters.Latin_1 A.3.3(25) +LC_D in Ada.Characters.Latin_1 A.3.3(13) +LC_E in Ada.Characters.Latin_1 A.3.3(13) +LC_E_Acute in Ada.Characters.Latin_1 A.3.3(25) +LC_E_Circumflex + in Ada.Characters.Latin_1 A.3.3(25) +LC_E_Diaeresis + in Ada.Characters.Latin_1 A.3.3(25) +LC_E_Grave in Ada.Characters.Latin_1 A.3.3(25) +LC_F in Ada.Characters.Latin_1 A.3.3(13) +LC_G in Ada.Characters.Latin_1 A.3.3(13) +LC_German_Sharp_S + in Ada.Characters.Latin_1 A.3.3(24) +LC_H in Ada.Characters.Latin_1 A.3.3(13) +LC_I in Ada.Characters.Latin_1 A.3.3(13) +LC_I_Acute in Ada.Characters.Latin_1 A.3.3(25) +LC_I_Circumflex + in Ada.Characters.Latin_1 A.3.3(25) +LC_I_Diaeresis + in Ada.Characters.Latin_1 A.3.3(25) +LC_I_Grave in Ada.Characters.Latin_1 A.3.3(25) +LC_Icelandic_Eth + in Ada.Characters.Latin_1 A.3.3(26) +LC_Icelandic_Thorn + in Ada.Characters.Latin_1 A.3.3(26) +LC_J in Ada.Characters.Latin_1 A.3.3(13) +LC_K in Ada.Characters.Latin_1 A.3.3(13) +LC_L in Ada.Characters.Latin_1 A.3.3(13) +LC_M in Ada.Characters.Latin_1 A.3.3(13) +LC_N in Ada.Characters.Latin_1 A.3.3(13) +LC_N_Tilde in Ada.Characters.Latin_1 A.3.3(26) +LC_O in Ada.Characters.Latin_1 A.3.3(13) +LC_O_Acute in Ada.Characters.Latin_1 A.3.3(26) + +LC_O_Circumflex + in Ada.Characters.Latin_1 A.3.3(26) +LC_O_Diaeresis + in Ada.Characters.Latin_1 A.3.3(26) +LC_O_Grave in Ada.Characters.Latin_1 A.3.3(26) +LC_O_Oblique_Stroke + in Ada.Characters.Latin_1 A.3.3(26) +LC_O_Tilde in Ada.Characters.Latin_1 A.3.3(26) +LC_P in Ada.Characters.Latin_1 A.3.3(14) +LC_Q in Ada.Characters.Latin_1 A.3.3(14) +LC_R in Ada.Characters.Latin_1 A.3.3(14) +LC_S in Ada.Characters.Latin_1 A.3.3(14) +LC_T in Ada.Characters.Latin_1 A.3.3(14) +LC_U in Ada.Characters.Latin_1 A.3.3(14) +LC_U_Acute in Ada.Characters.Latin_1 A.3.3(26) +LC_U_Circumflex + in Ada.Characters.Latin_1 A.3.3(26) +LC_U_Diaeresis + in Ada.Characters.Latin_1 A.3.3(26) +LC_U_Grave in Ada.Characters.Latin_1 A.3.3(26) +LC_V in Ada.Characters.Latin_1 A.3.3(14) +LC_W in Ada.Characters.Latin_1 A.3.3(14) +LC_X in Ada.Characters.Latin_1 A.3.3(14) +LC_Y in Ada.Characters.Latin_1 A.3.3(14) +LC_Y_Acute in Ada.Characters.Latin_1 A.3.3(26) +LC_Y_Diaeresis + in Ada.Characters.Latin_1 A.3.3(26) +LC_Z in Ada.Characters.Latin_1 A.3.3(14) +Leading_Nonseparate + in Interfaces.COBOL B.4(23) +Leading_Separate in Interfaces.COBOL B.4(23) +Left_Angle_Quotation + in Ada.Characters.Latin_1 A.3.3(21/3) +Left_Curly_Bracket + in Ada.Characters.Latin_1 A.3.3(14) +Left_Parenthesis + in Ada.Characters.Latin_1 A.3.3(8) +Left_Square_Bracket + in Ada.Characters.Latin_1 A.3.3(12) +Less_Than_Sign + in Ada.Characters.Latin_1 A.3.3(10) +Letter_Set + in Ada.Strings.Maps.Constants A.4.6(4) +LF in Ada.Characters.Latin_1 A.3.3(5) +Low_Line in Ada.Characters.Latin_1 A.3.3(12) +Low_Order_First + in Interfaces.COBOL B.4(25) + in System 13.7(15/2) +Lower_Case_Map + in Ada.Strings.Maps.Constants A.4.6(5) +Lower_Set + in Ada.Strings.Maps.Constants A.4.6(4) +Macron in Ada.Characters.Latin_1 A.3.3(21/3) +Masculine_Ordinal_Indicator + in Ada.Characters.Latin_1 A.3.3(22) +Max_Base_Digits in System 13.7(8) +Max_Binary_Modulus in System 13.7(7) +Max_Decimal_Digits in Ada.Decimal F.2(5) +Max_Delta in Ada.Decimal F.2(4) +Max_Digits in System 13.7(8) + +Q.5 Language-Defined Objects + +13 December 2012 864 + + Ada Reference Manual — 2012 Edition + +Max_Digits_Binary in Interfaces.COBOL B.4(11) +Max_Digits_Long_Binary + in Interfaces.COBOL B.4(11) +Max_Image_Width + in Ada.Numerics.Discrete_Random A.5.2(25) + in Ada.Numerics.Float_Random A.5.2(13) +Max_Int in System 13.7(6) +Max_Length in Ada.Strings.Bounded A.4.4(5) +Max_Mantissa in System 13.7(9) +Max_Nonbinary_Modulus in System 13.7(7) +Max_Picture_Length + in Ada.Text_IO.Editing F.3.3(8) +Max_Scale in Ada.Decimal F.2(3) +Memory_Size in System 13.7(13) +Micro_Sign in Ada.Characters.Latin_1 A.3.3(22) +Middle_Dot in Ada.Characters.Latin_1 A.3.3(22) +Min_Delta in Ada.Decimal F.2(4) +Min_Handler_Ceiling + in Ada.Execution_Time.Group_Budgets D.14.2(7/2) + in Ada.Execution_Time.Timers D.14.1(6/2) +Min_Int in System 13.7(6) +Min_Scale in Ada.Decimal F.2(3) +Minus_Sign in Ada.Characters.Latin_1 A.3.3(8) +Monday in Ada.Calendar.Formatting 9.6.1(17/2) +Multiplication_Sign + in Ada.Characters.Latin_1 A.3.3(24) +MW in Ada.Characters.Latin_1 A.3.3(18) +NAK in Ada.Characters.Latin_1 A.3.3(6) +Native_Binary in Interfaces.COBOL B.4(25) +NBH in Ada.Characters.Latin_1 A.3.3(17) +NBSP in Ada.Characters.Latin_1 A.3.3(21/3) +NEL in Ada.Characters.Latin_1 A.3.3(17) +No_Break_Space + in Ada.Characters.Latin_1 A.3.3(21/3) +No_Element + in Ada.Containers.Doubly_Linked_Lists A.18.3(9/2) + in Ada.Containers.Hashed_Maps A.18.5(6/2) + in Ada.Containers.Hashed_Sets A.18.8(6/2) + in Ada.Containers.Multiway_Trees A.18.10(11/3) + in Ada.Containers.Ordered_Maps A.18.6(7/2) + in Ada.Containers.Ordered_Sets A.18.9(7/2) + in Ada.Containers.Vectors A.18.2(11/2) +No_Index in Ada.Containers.Vectors A.18.2(7/2) +No_Tag in Ada.Tags 3.9(6.1/2) +Not_A_Specific_CPU + in System.Multiprocessors D.16(4/3) +Not_Sign in Ada.Characters.Latin_1 A.3.3(21/3) +NUL + in Ada.Characters.Latin_1 A.3.3(5) + in Interfaces.C B.3(20/1) +Null_Address in System 13.7(12) +Null_Bounded_String + in Ada.Strings.Bounded A.4.4(7) +Null_Id in Ada.Exceptions 11.4.1(2/2) +Null_Occurrence in Ada.Exceptions 11.4.1(3/2) +Null_Ptr in Interfaces.C.Strings B.3.1(7) +Null_Set + in Ada.Strings.Maps A.4.2(5) + in Ada.Strings.Wide_Maps A.4.7(5) + in Ada.Strings.Wide_Wide_Maps A.4.8(5/2) + +Null_Unbounded_String + in Ada.Strings.Unbounded A.4.5(5) +Number_Sign in Ada.Characters.Latin_1 A.3.3(8) +OSC in Ada.Characters.Latin_1 A.3.3(19) +Packed_Signed in Interfaces.COBOL B.4(27) +Packed_Unsigned in Interfaces.COBOL B.4(27) +Paragraph_Sign + in Ada.Characters.Latin_1 A.3.3(22) +Percent_Sign + in Ada.Characters.Latin_1 A.3.3(8) +Pi in Ada.Numerics A.5(3/2) +Pilcrow_Sign + in Ada.Characters.Latin_1 A.3.3(22) +PLD in Ada.Characters.Latin_1 A.3.3(17) +PLU in Ada.Characters.Latin_1 A.3.3(17) +Plus_Minus_Sign + in Ada.Characters.Latin_1 A.3.3(22) +Plus_Sign in Ada.Characters.Latin_1 A.3.3(8) +PM in Ada.Characters.Latin_1 A.3.3(19) +Pound_Sign in Ada.Characters.Latin_1 A.3.3(21/3) +PU1 in Ada.Characters.Latin_1 A.3.3(18) +PU2 in Ada.Characters.Latin_1 A.3.3(18) +Question in Ada.Characters.Latin_1 A.3.3(10) +Quotation in Ada.Characters.Latin_1 A.3.3(8) +Registered_Trade_Mark_Sign + in Ada.Characters.Latin_1 A.3.3(21/3) +Reserved_128 + in Ada.Characters.Latin_1 A.3.3(17) +Reserved_129 + in Ada.Characters.Latin_1 A.3.3(17) +Reserved_132 + in Ada.Characters.Latin_1 A.3.3(17) +Reserved_153 + in Ada.Characters.Latin_1 A.3.3(19) +Reverse_Solidus + in Ada.Characters.Latin_1 A.3.3(12) +RI in Ada.Characters.Latin_1 A.3.3(17) +Right_Angle_Quotation + in Ada.Characters.Latin_1 A.3.3(22) +Right_Curly_Bracket + in Ada.Characters.Latin_1 A.3.3(14) +Right_Parenthesis + in Ada.Characters.Latin_1 A.3.3(8) +Right_Square_Bracket + in Ada.Characters.Latin_1 A.3.3(12) +Ring_Above in Ada.Characters.Latin_1 A.3.3(22) +RS in Ada.Characters.Latin_1 A.3.3(6) +Saturday in Ada.Calendar.Formatting 9.6.1(17/2) +SCHAR_MAX in Interfaces.C B.3(6) +SCHAR_MIN in Interfaces.C B.3(6) +SCI in Ada.Characters.Latin_1 A.3.3(19) +Section_Sign + in Ada.Characters.Latin_1 A.3.3(21/3) +Semicolon in Ada.Characters.Latin_1 A.3.3(10) +Separate_Interrupt_Clocks_Supported + in Ada.Execution_Time D.14(9.2/3) +SI in Ada.Characters.Latin_1 A.3.3(5) +SO in Ada.Characters.Latin_1 A.3.3(5) +Soft_Hyphen in Ada.Characters.Latin_1 A.3.3(21/3) +SOH in Ada.Characters.Latin_1 A.3.3(5) + +865 13 December 2012 + +Language-Defined Objects Q.5 + + Ada Reference Manual — 2012 Edition + +Solidus in Ada.Characters.Latin_1 A.3.3(8) +SOS in Ada.Characters.Latin_1 A.3.3(19) +SPA in Ada.Characters.Latin_1 A.3.3(18) +Space + in Ada.Characters.Latin_1 A.3.3(8) + in Ada.Strings A.4.1(4/2) +Special_Set + in Ada.Strings.Maps.Constants A.4.6(4) +SS2 in Ada.Characters.Latin_1 A.3.3(17) +SS3 in Ada.Characters.Latin_1 A.3.3(17) +SSA in Ada.Characters.Latin_1 A.3.3(17) +ST in Ada.Characters.Latin_1 A.3.3(19) +Storage_Unit in System 13.7(13) +STS in Ada.Characters.Latin_1 A.3.3(18) +STX in Ada.Characters.Latin_1 A.3.3(5) +SUB in Ada.Characters.Latin_1 A.3.3(6) +Success in Ada.Command_Line A.15(8) +Sunday in Ada.Calendar.Formatting 9.6.1(17/2) +Superscript_One + in Ada.Characters.Latin_1 A.3.3(22) +Superscript_Three + in Ada.Characters.Latin_1 A.3.3(22) +Superscript_Two + in Ada.Characters.Latin_1 A.3.3(22) +SYN in Ada.Characters.Latin_1 A.3.3(6) +System_Dispatching_Domain + in System.Multiprocessors.Dispatching_Domains + +D.16.1(6/3) + +System_Name in System 13.7(4) +Thursday in Ada.Calendar.Formatting 9.6.1(17/2) +Tick + in Ada.Real_Time D.8(6) + in System 13.7(10) +Tilde in Ada.Characters.Latin_1 A.3.3(14) +Time_First in Ada.Real_Time D.8(4) +Time_Last in Ada.Real_Time D.8(4) +Time_Span_First in Ada.Real_Time D.8(5) +Time_Span_Last in Ada.Real_Time D.8(5) +Time_Span_Unit in Ada.Real_Time D.8(5) +Time_Span_Zero in Ada.Real_Time D.8(5) +Time_Unit in Ada.Real_Time D.8(4) +Trailing_Nonseparate + in Interfaces.COBOL B.4(23) +Trailing_Separate in Interfaces.COBOL B.4(23) +Tuesday in Ada.Calendar.Formatting 9.6.1(17/2) +UC_A_Acute in Ada.Characters.Latin_1 A.3.3(23) +UC_A_Circumflex + in Ada.Characters.Latin_1 A.3.3(23) +UC_A_Diaeresis + in Ada.Characters.Latin_1 A.3.3(23) +UC_A_Grave in Ada.Characters.Latin_1 A.3.3(23) +UC_A_Ring in Ada.Characters.Latin_1 A.3.3(23) +UC_A_Tilde in Ada.Characters.Latin_1 A.3.3(23) +UC_AE_Diphthong + in Ada.Characters.Latin_1 A.3.3(23) + +UC_C_Cedilla + in Ada.Characters.Latin_1 A.3.3(23) +UC_E_Acute in Ada.Characters.Latin_1 A.3.3(23) +UC_E_Circumflex + in Ada.Characters.Latin_1 A.3.3(23) +UC_E_Diaeresis + in Ada.Characters.Latin_1 A.3.3(23) +UC_E_Grave in Ada.Characters.Latin_1 A.3.3(23) +UC_I_Acute in Ada.Characters.Latin_1 A.3.3(23) +UC_I_Circumflex + in Ada.Characters.Latin_1 A.3.3(23) +UC_I_Diaeresis + in Ada.Characters.Latin_1 A.3.3(23) +UC_I_Grave in Ada.Characters.Latin_1 A.3.3(23) +UC_Icelandic_Eth + in Ada.Characters.Latin_1 A.3.3(24) +UC_Icelandic_Thorn + in Ada.Characters.Latin_1 A.3.3(24) +UC_N_Tilde in Ada.Characters.Latin_1 A.3.3(24) +UC_O_Acute in Ada.Characters.Latin_1 A.3.3(24) +UC_O_Circumflex + in Ada.Characters.Latin_1 A.3.3(24) +UC_O_Diaeresis + in Ada.Characters.Latin_1 A.3.3(24) +UC_O_Grave in Ada.Characters.Latin_1 A.3.3(24) +UC_O_Oblique_Stroke + in Ada.Characters.Latin_1 A.3.3(24) +UC_O_Tilde in Ada.Characters.Latin_1 A.3.3(24) +UC_U_Acute in Ada.Characters.Latin_1 A.3.3(24) +UC_U_Circumflex + in Ada.Characters.Latin_1 A.3.3(24) +UC_U_Diaeresis + in Ada.Characters.Latin_1 A.3.3(24) +UC_U_Grave in Ada.Characters.Latin_1 A.3.3(24) +UC_Y_Acute in Ada.Characters.Latin_1 A.3.3(24) +UCHAR_MAX in Interfaces.C B.3(6) +Unbounded in Ada.Text_IO A.10.1(5) +Unsigned in Interfaces.COBOL B.4(23) +Upper_Case_Map + in Ada.Strings.Maps.Constants A.4.6(5) +Upper_Set + in Ada.Strings.Maps.Constants A.4.6(4) +US in Ada.Characters.Latin_1 A.3.3(6) +Vertical_Line + in Ada.Characters.Latin_1 A.3.3(14) +VT in Ada.Characters.Latin_1 A.3.3(5) +VTS in Ada.Characters.Latin_1 A.3.3(17) +Wednesday in Ada.Calendar.Formatting 9.6.1(17/2) +Wide_Character_Set + in Ada.Strings.Wide_Maps.Wide_Constants A.4.8(48/2) +wide_nul in Interfaces.C B.3(31/1) +Wide_Space in Ada.Strings A.4.1(4/2) +Wide_Wide_Space in Ada.Strings A.4.1(4/2) +Word_Size in System 13.7(13) +Yen_Sign in Ada.Characters.Latin_1 A.3.3(21/3) + +Q.5 Language-Defined Objects + +13 December 2012 866 + + Ada Reference Manual — 2012 Edition + +Index entries are given by paragraph number. + +Index + +& operator 4.4(1/3), 4.5.3(3) + +* operator 4.4(1/3), 4.5.5(1) +** operator 4.4(1/3), 4.5.6(7) + ++ operator 4.4(1/3), 4.5.3(1), 4.5.4(1) + +- operator 4.4(1/3), 4.5.3(1), 4.5.4(1) + +/ operator 4.4(1/3), 4.5.5(1) +/= operator 4.4(1/3), 4.5.2(1), 6.6(6/3) + +10646:2011, ISO/IEC standard 1.2(8/3) +14882:2011, ISO/IEC standard 1.2(9/3) +1539-1:2004, ISO/IEC standard 1.2(3/2) +19769:2004, ISO/IEC technical report + +1.2(10/2) + +1989:2002, ISO standard 1.2(4/2) + +3166-1:2006, ISO/IEC standard + +1.2(4.1/3) + +639-3:2007, ISO standard 1.2(1.1/3) +6429:1992, ISO/IEC standard 1.2(5) +646:1991, ISO/IEC standard 1.2(2) + + used 5.1(4/2), P +Abort_Task + in Ada.Task_Identification C.7.1(3/3) +abortable_part 9.7.4(5) + used 9.7.4(2), P +abs operator 4.4(1/3), 4.5.6(1) +absolute value 4.4(1/3), 4.5.6(1) +abstract data type (ADT) + See private types and private + +access_to_subprogram_definition + +3.10(5) + + used 3.10(2/2), P +access_type_definition 3.10(2/2) + used 3.2.1(4/2), 12.5.4(2), P +accessibility + distributed 3.10.2(32.1/3) + from shared passive library units + +E.2.1(8) + +extensions 7.3(1) + + See also abstract type 3.9.3(1/2) +abstract subprogram 3.9.3(1/2), + +accessibility level 3.10.2(3/2) +accessibility rule + Access attribute 3.10.2(28/3), + +3.9.3(3/2) + +abstract type 3.9.3(1.2/2), 3.9.3(1/2), + +N(1.1/2) + +3.10.2(32/3) + + requeue statement 9.5.4(6/3) + type conversion 4.6(24.17/3), + +abstract_subprogram_declaration + +4.6(24.21/2) + +3.9.3(1.1/3) + used 3.1(3/3), P +accept_alternative 9.7.1(5) + used 9.7.1(4), P +accept_statement 9.5.2(3) + used 5.1(5/2), 9.7.1(5), P +acceptable interpretation 8.6(14) +Access attribute 3.10.2(24/1), + +3.10.2(32/3) + + See also Unchecked_Access attribute + + type conversion, array components + +4.6(24.6/2) + +Accessibility_Check 11.5(19.1/2) + [partial] 3.10.2(29), 4.6(39.1/2), +4.6(48/3), 4.8(10.1/3), 6.5(8/3), +6.5(21/3), 13.11.4(25/3), +13.11.4(26/3), E.4(18/1) +accessible partition E.1(7) +accuracy 4.6(32), G.2(1) +ACK + in Ada.Characters.Latin_1 A.3.3(5) +acquire + execution resource associated with + +protected object 9.5.1(5) + +activation + of a task 9.2(1) +activation failure 9.2(1) +Activation_Is_Complete + in Ada.Task_Identification C.7.1(4/3) +activator + of a task 9.2(5) +active locale A.19(8/3) +active partition 10.2(28/3), E.1(2) +active priority D.1(15) +actual 12.3(7/3) +actual duration D.9(12) +actual parameter + for a formal parameter 6.4.1(3) +actual subtype 3.3(23/3), 12.5(4) + of an object 3.3.1(9/2) +actual type 12.5(4) +actual_parameter_part 6.4(4) + used 4.1.6(10/3), 6.4(2), 6.4(3), + +9.5.3(2), P + +8859-1:1998, ISO/IEC standard 1.2(6/3) + +13.10(3) + +9899:2011, ISO/IEC standard 1.2(7/3) + +< operator 4.4(1/3), 4.5.2(1) +<= operator 4.4(1/3), 4.5.2(1) + += operator 4.4(1/3), 4.5.2(1) + +> operator 4.4(1/3), 4.5.2(1) +>= operator 4.4(1/3), 4.5.2(1) + +A + +AARM 0.2(5/3) +abnormal completion 7.6.1(2/2) +abnormal state of an object 13.9.1(4) + [partial] 9.8(21), 11.6(6/3), A.13(17) +abnormal task 9.8(4) +abort + of a partition E.1(7) + of a task 9.8(4) + of the execution of a construct 9.8(5) +abort completion point 9.8(15) +abort-deferred operation 9.8(5) +abort_statement 9.8(2) + +access discriminant 3.7(9/2) +access parameter 6.1(24/2) +access paths + distinct 6.2(12/3) +access result type 6.1(24/2) +access type 3.10(1), N(2) + subpool 13.11.4(22/3) +access types + input-output unspecified A.7(6) +access value 3.10(1) +access-to-constant type 3.10(10) +access-to-object type 3.10(7/1) +access-to-subprogram type 3.10(7/1), + +3.10(11) + +access-to-variable type 3.10(10) +Access_Check 11.5(11/2) + [partial] 4.1(13), 4.1.5(8/3), 4.6(51/3), + +4.8(10.4/3) + +access_definition 3.10(6/2) + used 3.3.1(2/3), 3.6(7/2), 3.7(5/2), +6.1(13/2), 6.1(15/3), 6.5(2.3/2), +8.5.1(2/3), 12.4(2/3), P + +access_to_object_definition 3.10(3) + used 3.10(2/2), P + +867 13 December 2012 + +Index + + + + + + + + + + + + + + + + + + Ada Reference Manual — 2012 Edition + +Actual_Quantum + in Ada.Dispatching.Round_Robin + +Ada.Containers.Synchronized_Queue_Inte + +Ada.Numerics.Generic_Elementary_- + +rfaces A.18.27(3/3) + +Functions A.5.1(3) + +D.2.5(4/2) + +Ada.Containers.Unbounded_Priority_Que + +Ada.Numerics.Generic_Real_Arrays + +ues A.18.30(2/3) + +G.3.1(2/2) + +Acute + in Ada.Characters.Latin_1 A.3.3(22) +Ada A.2(2) +Ada calling convention 6.3.1(3/3) +Ada.Ada.Unchecked_Deallocate_Subpool + + 13.11.5(3/3) + +Ada.Assertions 11.4.2(12/2) +Ada.Asynchronous_Task_Control + +Ada.Containers.Unbounded_Synchronize + +d_Queues A.18.28(2/3) + +Ada.Containers.Vectors A.18.2(6/3) +Ada.Decimal F.2(2) +Ada.Direct_IO A.8.4(2) +Ada.Directories A.16(3/2) +Ada.Directories.Hierarchical_File_Names + +D.11(3/2) + + A.16.1(3/3) + +Ada.Numerics.Real_Arrays G.3.1(31/2) +Ada.Real_Time D.8(3) +Ada.Real_Time.Timing_Events + +D.15(3/2) + +Ada.Sequential_IO A.8.1(2) +Ada.Storage_IO A.9(3) +Ada.Streams 13.13.1(2) +Ada.Streams.Stream_IO A.12.1(3/3) +Ada.Strings A.4.1(3) +Ada.Strings.Bounded A.4.4(3) +Ada.Strings.Bounded.Equal_Case_Insensi + +tive A.4.10(7/3) + +Ada.Calendar 9.6(10) +Ada.Calendar.Arithmetic 9.6.1(8/2) +Ada.Calendar.Formatting 9.6.1(15/2) +Ada.Calendar.Time_Zones 9.6.1(2/2) +Ada.Characters A.3.1(2) +Ada.Characters.Conversions A.3.4(2/2) +Ada.Characters.Handling A.3.2(2/2) +Ada.Characters.Latin_1 A.3.3(3) +Ada.Command_Line A.15(3) +Ada.Complex_Text_IO G.1.3(9.1/2) +Ada.Containers A.18.1(3/2) +Ada.Containers.Bounded_Priority_Queue + +Ada.Directories.Information A.16(124/2) +Ada.Dispatching D.2.1(1.2/3) +Ada.Dispatching.EDF D.2.6(9/2) +Ada.Dispatching.Non_Preemptive + +D.2.4(2.2/3) + +Ada.Dispatching.Round_Robin + +Ada.Strings.Bounded.Hash A.4.9(7/3) +Ada.Strings.Bounded.Hash_Case_Insensit + +D.2.5(4/2) + +ive A.4.9(11.7/3) + +Ada.Dynamic_Priorities D.5.1(3/2) +Ada.Environment_Variables A.17(3/2) +Ada.Exceptions 11.4.1(2/2) +Ada.Execution_Time D.14(3/2) +Ada.Execution_Time.Group_Budgets + +Ada.Strings.Bounded.Less_Case_Insensiti + +ve A.4.10(18/3) + +Ada.Strings.Equal_Case_Insensitive + +A.4.10(2/3) + +Ada.Strings.Fixed A.4.3(5) +Ada.Strings.Fixed.Equal_Case_Insensitive + +s A.18.31(2/3) + +D.14.2(3/3) + +Ada.Containers.Bounded_Synchronized_ + +Ada.Execution_Time.Interrupts + + A.4.10(5/3) + +Queues A.18.29(2/3) + +D.14.3(3/3) + +Ada.Strings.Fixed.Hash_Case_Insensitive + +Ada.Containers.Doubly_Linked_Lists + +A.18.3(5/3) + +Ada.Containers.Generic_Array_Sort + +A.18.26(3/2) + +Ada.Containers.Generic_Constrained_Arr + +Ada.Execution_Time.Timers D.14.1(3/2) +Ada.Finalization 7.6(4/3) +Ada.Float_Text_IO A.10.9(33) +Ada.Float_Wide_Text_IO A.11(2/2) +Ada.Float_Wide_Wide_Text_IO + +ay_Sort A.18.26(7/2) +Ada.Containers.Generic_Sort + +A.18.26(9.2/3) + +Ada.Containers.Hashed_Maps + +A.18.5(2/3) + +A.11(3/2) + +Ada.Integer_Text_IO A.10.8(21) +Ada.Integer_Wide_Text_IO A.11(2/2) +Ada.Integer_Wide_Wide_Text_IO + +A.11(3/2) + +Ada.Containers.Hashed_Sets A.18.8(2/3) +Ada.Containers.Indefinite_Doubly_Linke + +d_Lists A.18.12(2/3) + +Ada.Containers.Indefinite_Hashed_Maps + +A.18.13(2/3) + +Ada.Containers.Indefinite_Hashed_Sets + +A.18.15(2/3) + +Ada.Interrupts C.3.2(2/3) +Ada.Interrupts.Names C.3.2(12) +Ada.IO_Exceptions A.13(3) +Ada.Iterator_Interfaces 5.5.1(2/3) +Ada.Locales A.19(3/3) +Ada.Numerics A.5(3/2) +Ada.Numerics.Complex_Arrays + +Ada.Strings.Fixed.Less_Case_Insensitive + + A.4.9(11.5/3) + +A.4.10(16/3) + +Ada.Strings.Hash A.4.9(2/3) +Ada.Strings.Hash_Case_Insensitive + +A.4.9(11.2/3) + +Ada.Strings.Less_Case_Insensitive + +A.4.10(13/3) + +Ada.Strings.Maps A.4.2(3/2) +Ada.Strings.Maps.Constants A.4.6(3/2) +Ada.Strings.Unbounded A.4.5(3) +Ada.Strings.Unbounded.Equal_Case_Inse + +nsitive A.4.10(10/3) +Ada.Strings.Unbounded.Hash + +A.4.9(10/3) + +Ada.Strings.Unbounded.Hash_Case_Insen + +sitive A.4.9(11.10/3) + +Ada.Containers.Indefinite_Holders + +G.3.2(53/2) + +Ada.Strings.Unbounded.Less_Case_Insen + +A.18.18(5/3) + +Ada.Numerics.Complex_Elementary_- + +sitive A.4.10(21/3) + +Ada.Containers.Indefinite_Multiway_Tree + +Functions G.1.2(9/1) + +s A.18.17(2/3) + +Ada.Numerics.Complex_Types + +Ada.Strings.UTF_Encoding A.4.11(3/3) +Ada.Strings.UTF_Encoding.Conversions + +Ada.Containers.Indefinite_Ordered_Maps + +G.1.1(25/1) + +A.4.11(15/3) + + A.18.14(2/3) + +Ada.Numerics.Discrete_Random + +Ada.Strings.UTF_Encoding.Strings + +Ada.Containers.Indefinite_Ordered_Sets + +A.5.2(17) + +A.4.11(22/3) + +A.18.16(2/3) + +Ada.Numerics.Elementary_Functions + +Ada.Strings.UTF_Encoding.Wide_Strings + +Ada.Containers.Indefinite_Vectors + +A.5.1(9/1) + + A.4.11(30/3) + +A.18.11(2/3) + +Ada.Containers.Multiway_Trees + +A.18.10(7/3) + +Ada.Numerics.Float_Random A.5.2(5) +Ada.Numerics.Generic_Complex_Arrays + +G.3.2(2/2) + +Ada.Containers.Ordered_Maps + +Ada.Numerics.Generic_Complex_- + +Ada.Strings.UTF_Encoding.Wide_Wide_ + +Strings A.4.11(38/3) + +Ada.Strings.Wide_Bounded A.4.7(1/3) +Ada.Strings.Wide_Bounded.Wide_- + +A.18.6(2/3) + +Ada.Containers.Ordered_Sets + +Elementary_Functions G.1.2(2/2) +Ada.Numerics.Generic_Complex_Types + +Equal_Case_Insensitive A.4.7(1/3) +Ada.Strings.Wide_Bounded.Wide_Hash + +A.18.9(2/3) + +G.1.1(2/1) + +A.4.7(1/3) + +Index + +13 December 2012 868 + + Ada Reference Manual — 2012 Edition + +Ada.Strings.Wide_Bounded.Wide_- + +Ada.Strings.Wide_Wide_- + +Hash_Case_Insensitive A.4.7(1/3) + +Ada.Strings.Wide_- + +Unbounded.Wide_Wide_- +Equal_Case_Insensitive A.4.8(1/3) + +Equal_Case_Insensitive A.4.7(1/3) + +Ada.Strings.Wide_Wide_- + +Ada.Strings.Wide_Fixed A.4.7(1/3) +Ada.Strings.Wide_Fixed.Wide_- + +Unbounded.Wide_Wide_Hash +A.4.8(1/3) + +Equal_Case_Insensitive A.4.7(1/3) + +Ada.Strings.Wide_Wide_- + +Ada.Strings.Wide_Fixed.Wide_Hash + +A.4.7(1/3) + +Ada.Strings.Wide_Fixed.Wide_- + +Hash_Case_Insensitive A.4.7(1/3) + +Ada.Strings.Wide_Hash A.4.7(1/3) +Ada.Strings.Wide_- + +Hash_Case_Insensitive A.4.7(1/3) + +Ada.Strings.Wide_Maps A.4.7(3) +Ada.Strings.Wide_Maps.Wide_- + +Constants A.4.7(1/3), A.4.8(28/2) + +Ada.Strings.Wide_Unbounded + +A.4.7(1/3) + +Ada.Strings.Wide_Unbounded.Wide_- + +Equal_Case_Insensitive A.4.7(1/3) + +Ada.Strings.Wide_Unbounded.Wide_- + +Hash A.4.7(1/3) + +Ada.Strings.Wide_Unbounded.Wide_- +Hash_Case_Insensitive A.4.7(1/3) + +Ada.Strings.Wide_Wide_Bounded + +Unbounded.Wide_Wide_- +Hash_Case_Insensitive A.4.8(1/3) +Ada.Synchronous_Barriers D.10.1(3/3) +Ada.Synchronous_Task_Control + +D.10(3/2) + +Ada.Synchronous_Task_Control.EDF + +D.10(5.2/3) +Ada.Tags 3.9(6/2) +Ada.Tags.Generic_Dispatching_- +Constructor 3.9(18.2/3) +Ada.Task_Attributes C.7.2(2) +Ada.Task_Identification C.7.1(2/2) +Ada.Task_Termination C.7.3(2/2) +Ada.Text_IO A.10.1(2) +Ada.Text_IO.Bounded_IO A.10.11(3/2) +Ada.Text_IO.Complex_IO G.1.3(3) +Ada.Text_IO.Editing F.3.3(3) +Ada.Text_IO.Text_Streams A.12.2(3) +Ada.Text_IO.Unbounded_IO + +A.4.8(1/3) + +A.10.12(3/2) + +Ada.Strings.Wide_Wide_- +Bounded.Wide_Wide_- +Equal_Case_Insensitive A.4.8(1/3) + +Ada.Strings.Wide_Wide_- + +Bounded.Wide_Wide_Hash +A.4.8(1/3) + +Ada.Strings.Wide_Wide_- +Bounded.Wide_Wide_- +Hash_Case_Insensitive A.4.8(1/3) + +Ada.Strings.Wide_Wide_- + +Ada.Unchecked_Conversion 13.9(3/3) +Ada.Unchecked_Deallocate_Subpool + child of Ada 13.11.5(3/3) +Ada.Unchecked_Deallocation + +13.11.2(3/3) + +Ada.Wide_Characters A.3.1(4/2) +Ada.Wide_Characters.Handling + +A.3.5(3/3) + +Ada.Wide_Text_IO A.11(2/2) +Ada.Wide_Text_IO.Bounded_IO + +Equal_Case_Insensitive A.4.8(1/3) + +A.11(4/3) + +Ada.Strings.Wide_Wide_Fixed + +Ada.Wide_Text_IO.Complex_IO + +A.4.8(1/3) + +G.1.4(1) + +Ada.Strings.Wide_Wide_- +Fixed.Wide_Wide_- +Equal_Case_Insensitive A.4.8(1/3) + +Ada.Wide_Text_IO.Editing F.3.4(1) +Ada.Wide_Text_IO.Text_Streams + +A.12.3(3) + +Ada.Strings.Wide_Wide_- + +Ada.Wide_Text_IO.Unbounded_IO + +Ada_To_COBOL + in Interfaces.COBOL B.4(14) +adafinal B.1(39/3) +adainit B.1(39/3) +Add + in + +Ada.Execution_Time.Group_Budgets +D.14.2(9/2) + +Add_Task + in + +Ada.Execution_Time.Group_Budgets +D.14.2(8/2) + +address + arithmetic 13.7.1(6) + comparison 13.7(14/3) + in System 13.7(12) +Address aspect 13.3(12) +Address attribute 13.3(11), J.7.1(5) +Address clause 13.3(7/2), 13.3(12) +Address_To_Access_Conversions + child of System 13.7.2(2) +Adjacent attribute A.5.3(48) +Adjust 7.6(2) + in Ada.Finalization 7.6(6/2) +adjusting the value of an object 7.6(15), + +7.6(16/3) + +adjustment 7.6(15), 7.6(16/3) + as part of assignment 5.2(14/3) +ADT (abstract data type) + See private types and private + +extensions 7.3(1) + + See also abstract type 3.9.3(1/2) +advice 1.1.2(37) +Aft attribute 3.5.10(5) +aggregate 4.3(1), 4.3(2) + used 4.4(7/3), 4.7(2), P + See also composite type 3.2(2/2) +aliased 3.10(9/3), N(3) +aliasing + See distinct access paths 6.2(12/3) +Alignment + in Ada.Strings A.4.1(6) +Alignment (subtype) aspect 13.3(26.4/2) +Alignment attribute 13.3(23/2), + +Fixed.Wide_Wide_Hash A.4.8(1/3) + +A.11(5/3) + +13.3(26.2/2) + +Ada.Wide_Wide_Characters A.3.1(6/2) +Ada.Wide_Wide_Characters.Handling + +Alignment clause 13.3(7/2), 13.3(25/2), + +13.3(26.4/2) + +Ada.Strings.Wide_Wide_- +Fixed.Wide_Wide_- +Hash_Case_Insensitive A.4.8(1/3) + +Ada.Strings.Wide_Wide_Hash + +A.4.8(1/3) + +A.3.6(1/3) + +Ada.Wide_Wide_Text_IO A.11(3/2) +Ada.Wide_Wide_Text_IO.Bounded_IO + +Ada.Strings.Wide_Wide_- + +A.11(4/3) + +Hash_Case_Insensitive A.4.8(1/3) + +Ada.Wide_Wide_Text_IO.Complex_IO + +Ada.Strings.Wide_Wide_Maps + +G.1.5(1/2) + +All_Calls_Remote aspect E.2.3(16/3) +All_Calls_Remote pragma E.2.3(5), L(2) +All_Checks 11.5(25/3) +Allocate + in System.Storage_Pools 13.11(7) + in System.Storage_Pools.Subpools + +A.4.8(3/2) + +Ada.Wide_Wide_Text_IO.Editing + +13.11.4(14/3) + +Ada.Strings.Wide_Wide_- + +F.3.5(1/2) + +Maps.Wide_Wide_Constants +A.4.8(1/3) + +Ada.Strings.Wide_Wide_Unbounded + +Ada.Wide_Wide_Text_IO.Text_Streams + +A.12.4(3/2) +Ada.Wide_Wide_- + +A.4.8(1/3) + +Text_IO.Unbounded_IO A.11(5/3) + +Allocate_From_Subpool + in System.Storage_Pools.Subpools + +13.11.4(11/3) + +Allocation_Check 11.5(19.2/2) + [partial] 4.8(10.2/2), 4.8(10.3/2), + +4.8(10.4/3), 13.11.4(30/3) + +869 13 December 2012 + +Index + + Ada Reference Manual — 2012 Edition + +allocator 4.8(2/3) + used 4.4(7/3), P +Alphanumeric + in Interfaces.COBOL B.4(16/3) +alphanumeric character + a category of Character A.3.2(31) +Alphanumeric_Set + in Ada.Strings.Maps.Constants + +A.4.6(4) + +ambiguous 8.6(30) +ambiguous cursor + of a vector A.18.2(240/2) +ampersand 2.1(15/3) + in Ada.Characters.Latin_1 A.3.3(8) +ampersand operator 4.4(1/3), 4.5.3(3) +ancestor N(3.1/2) + of a library unit 10.1.1(11) + of a tree node A.18.10(4/3) + of a type 3.4.1(10/2) + ultimate 3.4.1(10/2) +ancestor subtype + of a formal derived type 12.5.1(5/3) + of a private_extension_declaration + +7.3(8) +ancestor type + of an extension_aggregate 4.3.2(5/3) +Ancestor_Find + in Ada.Containers.Multiway_Trees + +A.18.10(40/3) +ancestor_part 4.3.2(3) + used 4.3.2(2), P +and operator 4.4(1/3), 4.5.1(2) +and then (short-circuit control form) + +4.4(1/3), 4.5.1(1) +angle threshold G.2.4(10) +Annex + informative 1.1.2(18) + normative 1.1.2(14) + Specialized Needs 1.1.2(7) +Annotated Ada Reference Manual + +0.2(5/3) + +anonymous access type 3.10(12/3) +anonymous allocator 3.10.2(14/3) +anonymous array type 3.3.1(1/3) +anonymous protected type 3.3.1(1/3) +anonymous task type 3.3.1(1/3) +anonymous type 3.2.1(7/2) +Any_Priority subtype of Integer + in System 13.7(16) +APC + in Ada.Characters.Latin_1 A.3.3(19) +apostrophe 2.1(15/3) + in Ada.Characters.Latin_1 A.3.3(8) +Append + in Ada.Containers.Doubly_Linked_- + +Lists A.18.3(23/2) + in Ada.Containers.Vectors +A.18.2(46/2), A.18.2(47/2) + + in Ada.Strings.Bounded A.4.4(13), +A.4.4(14), A.4.4(15), A.4.4(16), +A.4.4(17), A.4.4(18), A.4.4(19), +A.4.4(20) + +Arcsinh + in Ada.Numerics.Generic_Complex_- +Elementary_Functions G.1.2(7) + in Ada.Numerics.Generic_Elementary_- + + in Ada.Strings.Unbounded A.4.5(12), + +Functions A.5.1(7) + +A.4.5(13), A.4.5(14) + +Append_Child + in Ada.Containers.Multiway_Trees + +A.18.10(52/3) + +applicable index constraint 4.3.3(10) +application areas 1.1.2(7) +applies + aspect 13.1.1(23/3), 13.1.1(27/3), + +13.1.1(29/3), 13.1.1(30/3) + +apply + to a callable construct by a return + +statement 6.5(4/2) + to a loop_statement by an +exit_statement 5.7(4) + + to a program unit by a program unit + +pragma 10.1.5(2) +arbitrary order 1.1.4(18) + allowed 2.8(12), 3.3.1(20/2), 3.5(9), +3.6(22/2), 3.11(10/1), 3.11(11/3), +3.11(13), 4.1.1(7), 4.1.2(7), 4.3(5), +4.3.1(19), 4.3.2(7), 4.3.3(22), +4.3.3(23), 4.5.2(27/3), 4.8(10/2), +5.2(7), 6.1.1(26/3), 6.1.1(34/3), +6.1.1(35/3), 6.4(10/2), 6.4.1(17), +7.6(12), 7.6(16/3), 7.6.1(9/3), +7.6.1(11.1/3), 7.6.1(20.2/3), 9.7.1(15), +9.8(4), 12.3(20), 13.11.5(7/3), +K.2(164.2/3) + +Arccos + in Ada.Numerics.Generic_Complex_- +Elementary_Functions G.1.2(5) + in Ada.Numerics.Generic_Elementary_- + +Functions A.5.1(6) + +Arccosh + in Ada.Numerics.Generic_Complex_- +Elementary_Functions G.1.2(7) + in Ada.Numerics.Generic_Elementary_- + +Functions A.5.1(7) + +Arccot + in Ada.Numerics.Generic_Complex_- +Elementary_Functions G.1.2(5) + in Ada.Numerics.Generic_Elementary_- + +Functions A.5.1(6) + +Arccoth + in Ada.Numerics.Generic_Complex_- +Elementary_Functions G.1.2(7) + in Ada.Numerics.Generic_Elementary_- + +Functions A.5.1(7) + +Arcsin + in Ada.Numerics.Generic_Complex_- +Elementary_Functions G.1.2(5) + in Ada.Numerics.Generic_Elementary_- + +Functions A.5.1(6) + +Arctan + in Ada.Numerics.Generic_Complex_- +Elementary_Functions G.1.2(5) + in Ada.Numerics.Generic_Elementary_- + +Functions A.5.1(6) + +Arctanh + in Ada.Numerics.Generic_Complex_- +Elementary_Functions G.1.2(7) + in Ada.Numerics.Generic_Elementary_- + +Functions A.5.1(7) + +Argument + in Ada.Command_Line A.15(5) + in Ada.Numerics.Generic_Complex_- +Arrays G.3.2(10/2), G.3.2(31/2) + in Ada.Numerics.Generic_Complex_- + +Types G.1.1(10) + +argument of a pragma 2.8(9) +Argument_Count + in Ada.Command_Line A.15(4) +Argument_Error + in Ada.Numerics A.5(3/2) +Arithmetic + child of Ada.Calendar 9.6.1(8/2) +array 3.6(1) +array component expression 4.3.3(6) +array component iterator 5.5.2(3/3) +array for a loop 5.5.2(11/3) +array indexing + See indexed_component 4.1.1(1) +array slice 4.1.2(1) +array type 3.6(1), N(4) +array_aggregate 4.3.3(2) + used 4.3(2), 13.4(3), P +array_component_association 4.3.3(5/2) + used 4.3.3(4), P +array_type_definition 3.6(2) + used 3.2.1(4/2), 3.3.1(2/3), 12.5.3(2), P +ASCII + package physically nested within the + +declaration of Standard A.1(36.3/2) + + in Standard A.1(36.3/2) +aspect 13.1(0.1/3), K.1(1/3), N(4.1/3) + interfacing B.1(0.1/3) + predicate 3.2.4(1/3) +aspect of representation 13.1(8/3) +aspect_clause 13.1(2/1) + used 3.8(5/1), 3.11(4/1), 9.1(5/1), + +9.4(5/1), 9.4(8/1), P + +aspect_definition 13.1.1(4/3) + used 13.1.1(2/3), P +aspect_mark 13.1.1(3/3) + used 2.8(3/3), 11.4.2(6.1/3), +13.1.1(2/3), L(2.3/3), P +aspect_specification 13.1.1(2/3) + +Index + +13 December 2012 870 + + Ada Reference Manual — 2012 Edition + + used 3.2.1(3/3), 3.2.2(2/3), 3.3.1(2/3), + +3.8(6/3), 3.9.3(1.1/3), 6.1(2/3), +6.3(2/3), 6.7(2/3), 6.8(2/3), 7.1(3/3), +7.2(2/3), 7.3(2/3), 7.3(3/3), 8.5.1(2/3), +8.5.2(2/3), 8.5.3(2/3), 8.5.4(2/3), +8.5.5(2/3), 9.1(2/3), 9.1(3/3), 9.1(6/3), +9.4(2/3), 9.4(3/3), 9.4(7/3), 9.5.2(2/3), +10.1.3(3/3), 10.1.3(4), 10.1.3(5), +10.1.3(6), 11.1(2/3), 12.1(3/3), +12.3(2/3), 12.4(2/3), 12.5(2.1/3), +12.6(2.1/3), 12.6(2.2/3), 12.7(2/3), P + +aspects + Address 13.3(12) + Alignment (subtype) 13.3(26.4/2) + All_Calls_Remote E.2.3(16/3) + Asynchronous E.4.1(8.1/3) + Atomic C.6(6.2/3) + Atomic_Components C.6(6.6/3) + Attach_Handler C.3.1(6.3/3) + Bit_Order 13.5.3(4) + Coding 13.4(7) + Component_Size 13.3(70) + Constant_Indexing 4.1.6(2/3) + Convention B.1(2/3) + CPU D.16(8/3) + Default_Component_Value 3.6(22.2/3) + Default_Iterator 5.5.1(8/3) + Default_Storage_Pool 13.11.3(5/3) + Default_Value 3.5(56.3/3) + Dispatching_Domain D.16.1(18/3) + Dynamic_Predicate 3.2.4(1/3) + Elaborate_Body 10.2.1(26.1/3) + Export B.1(1/3) + External_Name B.1(1/3) + External_Tag 13.3(75/3), K.2(65) + Implicit_Dereference 4.1.5(2/3) + Import B.1(1/3) + Independent C.6(6.3/3) + Independent_Components C.6(6.9/3) + Inline 6.3.2(5.1/3) + Input 13.13.2(38/3) + Interrupt_Handler C.3.1(6.2/3) + Interrupt_Priority D.1(6.3/3) + Iterator_Element 5.5.1(9/3) + Layout 13.5(1) + Link_Name B.1(1/3) + Machine_Radix F.1(1) + No_Return 6.5.1(3.2/3) + Output 13.13.2(38/3) + Pack 13.2(5.1/3) + Post 6.1.1(4/3) + Post'Class 6.1.1(5/3) + Pre 6.1.1(2/3) + Pre'Class 6.1.1(3/3) + Preelaborate 10.2.1(11/3) + Priority D.1(6.2/3) + Pure 10.2.1(17/3) + Read 13.13.2(38/3) + Record layout 13.5(1) + Relative_Deadline D.2.6(9.2/3) + + Remote_Call_Interface E.2.3(7/3) + Remote_Types E.2.2(4/3) + Shared_Passive E.2.1(4/3) + Size (object) 13.3(41) + Size (subtype) 13.3(48) + Small 3.5.10(2/1) + Static_Predicate 3.2.4(1/3) + Storage_Pool 13.11(15) + Storage_Size (access) 13.11(15) + Storage_Size (task) 13.3(65.2/3) + Stream_Size 13.13.2(1.5/2) + Synchronization 9.5(12/3) + Type_Invariant 7.3.2(2/3) + Type_Invariant'Class 7.3.2(3/3) + Unchecked_Union B.3.3(3.2/3) + Variable_Indexing 4.1.6(3/3) + Volatile C.6(6.4/3) + Volatile_Components C.6(6.7/3) + Write 13.13.2(38/3) +assembly language C.1(4/3) +Assert + in Ada.Assertions 11.4.2(14/2) +Assert pragma 11.4.2(3/2), L(2.1/2) +assertion N(4.2/3) +assertion expressions 11.4.2(1.1/3) +assertion policy + Assert pragma 11.4.2(18/3) +Assertion_Error + raised by failure of assertion + +11.4.2(18/3) + + raised by failure of run-time check +3.2.4(31/3), 4.6(57/3), 6.1.1(32/3), +6.1.1(33/3), 6.1.1(35/3), 7.3.2(22/3) + + in Ada.Assertions 11.4.2(13/2) +Assertion_Policy pragma 11.4.2(6.1/3), + +11.4.2(6/2), L(2.2/2), L(2.3/3) + +assertions 11.4.2(1.1/3) + child of Ada 11.4.2(12/2) +Assign + in Ada.Containers.Doubly_Linked_- + +Lists A.18.3(17.5/3) + + in Ada.Containers.Hashed_Maps + + in Ada.Containers.Hashed_Sets + +A.18.5(17.7/3) + +A.18.8(17.3/3) + +A.18.18(20/3) + + in Ada.Containers.Indefinite_Holders + + in Ada.Containers.Multiway_Trees + +assigning back of parameters 6.4.1(17) +assignment + user-defined 7.6(1) +assignment operation 5.2(3), 5.2(12), + +7.6(13) + + during elaboration of an + +object_declaration 3.3.1(18/2) + + during evaluation of a + +generic_association for a formal object +of mode in 12.4(11) + during evaluation of a + +parameter_association 6.4.1(11) + during evaluation of an aggregate + +4.3(5) + + during evaluation of an initialized + +allocator 4.8(7/2) + + during evaluation of an uninitialized + +allocator 4.8(9/2) + + during evaluation of concatenation + +4.5.3(10) + + during execution of a for loop 5.5(9/3) + during execution of an + +assignment_statement 5.2(12) + during parameter copy back 6.4.1(17) +assignment_statement 5.2(2) + used 5.1(4/2), P +associated components + of a record_component_association + +4.3.1(10) + +associated declaration + of an aspect specification 13.1.1(1/3) +associated discriminants + of a named discriminant_association + +3.7.1(5) + + of a positional discriminant_association + +3.7.1(5) +associated entity + of an aspect specification 13.1.1(5/3) +associated object + of a value of a by-reference type + +6.2(10/3) +asterisk 2.1(15/3) + in Ada.Characters.Latin_1 A.3.3(8) +asynchronous + remote procedure call E.4.1(9/3) +Asynchronous aspect E.4.1(8.1/3) +Asynchronous pragma J.15.13(2/3), + +L(3.1/3) + +A.18.10(32/3) + +asynchronous remote procedure call + + in Ada.Containers.Ordered_Maps + + in Ada.Containers.Ordered_Sets + +A.18.6(16.7/3) + +A.18.9(16.3/3) + + in Ada.Containers.Vectors + +A.18.2(34.7/3) + + See assignment operation 5.2(3) +Assign_Task + in + +System.Multiprocessors.Dispatching_ +Domains D.16.1(11/3) + +E.4(1) + +asynchronous_select 9.7.4(2) + used 9.7(2), P +Asynchronous_Task_Control + child of Ada D.11(3/2) +at-most-once execution E.4(11) +at_clause J.7(1) + used 13.1(2/1), P +atomic C.6(7/3) +Atomic aspect C.6(6.2/3) +Atomic pragma J.15.8(2/3), L(4.1/3) + +871 13 December 2012 + +Index + + Ada Reference Manual — 2012 Edition + +Atomic_Components aspect C.6(6.6/3) +Atomic_Components pragma J.15.8(5/3), + +L(5.1/3) +Attach_Handler + in Ada.Interrupts C.3.2(7) +Attach_Handler aspect C.3.1(6.3/3) +Attach_Handler pragma J.15.7(4/3), + +L(6.1/3) + +attaching + to an interrupt C.3(2) +attribute 4.1.4(1), K.2(1/3) + representation 13.3(1/1) + specifiable 13.3(5/3) + specifying 13.3(1/1) +attribute_definition_clause 13.3(2) + used 13.1(2/1), P +attribute_designator 4.1.4(3/2) + used 4.1.4(2), 13.1(3), 13.3(2), P +Attribute_Handle + in Ada.Task_Attributes C.7.2(3) +attribute_reference 4.1.4(2) + used 4.1(2/3), P +attributes + Access 3.10.2(24/1), 3.10.2(32/3) + Address 13.3(11), J.7.1(5) + Adjacent A.5.3(48) + Aft 3.5.10(5) + Alignment 13.3(23/2), 13.3(26.2/2) + Base 3.5(15) + Bit_Order 13.5.3(4) + Body_Version E.3(4) + Callable 9.9(2) + Caller C.7.1(14/3) + Ceiling A.5.3(33) + Class 3.9(14), 7.3.1(9), J.11(2/2) + Component_Size 13.3(69) + Compose A.5.3(24) + Constrained 3.7.2(3/3), J.4(2) + Copy_Sign A.5.3(51) + Count 9.9(5) + Definite 12.5.1(23/3) + Delta 3.5.10(3) + Denorm A.5.3(9) + Digits 3.5.8(2/1), 3.5.10(7) + Exponent A.5.3(18) + External_Tag 13.3(75/3) + First 3.5(12), 3.6.2(3) + First(N) 3.6.2(4) + First_Bit 13.5.2(3/2) + First_Valid 3.5.5(7.2/3) + Floor A.5.3(30) + Fore 3.5.10(4) + Fraction A.5.3(21) + Has_Same_Storage 13.3(73.2/3) + Identity 11.4.1(9), C.7.1(12) + Image 3.5(35) + Input 13.13.2(22), 13.13.2(32) + Last 3.5(13), 3.6.2(5) + Last(N) 3.6.2(6) + Last_Bit 13.5.2(4/2) + + Last_Valid 3.5.5(7.3/3) + Leading_Part A.5.3(54) + Length 3.6.2(9) + Length(N) 3.6.2(10) + Machine A.5.3(60) + Machine_Emax A.5.3(8) + Machine_Emin A.5.3(7) + Machine_Mantissa A.5.3(6) + Machine_Overflows A.5.3(12), + +A.5.4(4) + + Machine_Radix A.5.3(2), A.5.4(2) + Machine_Rounding A.5.3(41.1/2) + Machine_Rounds A.5.3(11), A.5.4(3) + Max 3.5(19) + Max_Alignment_For_Allocation + +13.11.1(4/3) + + Max_Size_In_Storage_Elements + +13.11.1(3/3) + Min 3.5(16) + Mod 3.5.4(16.1/2) + Model A.5.3(68), G.2.2(7) + Model_Emin A.5.3(65), G.2.2(4) + Model_Epsilon A.5.3(66) + Model_Mantissa A.5.3(64), G.2.2(3/2) + Model_Small A.5.3(67) + Modulus 3.5.4(17) + Old 6.1.1(26/3) + Output 13.13.2(19), 13.13.2(29) + Overlaps_Storage 13.3(73.6/3) + Partition_Id E.1(9) + Pos 3.5.5(2) + Position 13.5.2(2/2) + Pred 3.5(25) + Priority D.5.2(3/2) + Range 3.5(14), 3.6.2(7) + Range(N) 3.6.2(8) + Read 13.13.2(6), 13.13.2(14) + Remainder A.5.3(45) + Result 6.1.1(29/3) + Round 3.5.10(12) + Rounding A.5.3(36) + Safe_First A.5.3(71), G.2.2(5) + Safe_Last A.5.3(72), G.2.2(6) + Scale 3.5.10(11) + Scaling A.5.3(27) + Signed_Zeros A.5.3(13) + Size 13.3(40), 13.3(45) + Small 3.5.10(2/1) + Storage_Pool 13.11(13) + Storage_Size 13.3(60/3), 13.11(14), + +J.9(2) + + Stream_Size 13.13.2(1.2/3) + Succ 3.5(22) + Tag 3.9(16), 3.9(18) + Terminated 9.9(3) + Truncation A.5.3(42) + Unbiased_Rounding A.5.3(39) + Unchecked_Access 13.10(3), H.4(18) + Val 3.5.5(5) + Valid 13.9.2(3/3), H(6) + + Value 3.5(52) + Version E.3(3) + Wide_Image 3.5(28) + Wide_Value 3.5(40) + Wide_Wide_Image 3.5(27.1/2) + Wide_Wide_Value 3.5(39.1/2) + Wide_Wide_Width 3.5(37.1/2) + Wide_Width 3.5(38) + Width 3.5(39) + Write 13.13.2(3), 13.13.2(11) +available + stream attribute 13.13.2(39/2) + +B + +Backus-Naur Form (BNF) + complete listing P + cross reference P + notation 1.1.4(3) + under Syntax heading 1.1.2(25) +Barrier_Limit subtype of Positive + in Ada.Synchronous_Barriers + +D.10.1(4/3) + +base 2.4.2(3), 2.4.2(6) + used 2.4.2(2), P +base 16 literal 2.4.2(1) +base 2 literal 2.4.2(1) +base 8 literal 2.4.2(1) +Base attribute 3.5(15) +base decimal precision + of a floating point type 3.5.7(9) + of a floating point type 3.5.7(10) +base priority D.1(15) +base range + of a decimal fixed point type 3.5.9(16) + of a fixed point type 3.5.9(12) + of a floating point type 3.5.7(8), + +3.5.7(10) + + of a modular type 3.5.4(10) + of a scalar type 3.5(6) + of a signed integer type 3.5.4(9) + of an ordinary fixed point type + +3.5.9(13) +base subtype + of a type 3.5(15) +Base_Name + in Ada.Directories A.16(19/2) +based_literal 2.4.2(2) + used 2.4(2), P +based_numeral 2.4.2(4) + used 2.4.2(2), P +basic letter + a category of Character A.3.2(27) +basic_declaration 3.1(3/3) + used 3.11(4/1), P +basic_declarative_item 3.11(4/1) + used 3.11(3), 7.1(3/3), P +Basic_Map + in Ada.Strings.Maps.Constants + +A.4.6(5) + +Index + +13 December 2012 872 + + + + Ada Reference Manual — 2012 Edition + +Basic_Set + in Ada.Strings.Maps.Constants + +A.4.6(4) + +become nonlimited 7.3.1(5/1), 7.5(16) +BEL + in Ada.Characters.Latin_1 A.3.3(5) +belong + to a range 3.5(4) + to a subtype 3.2(8/2) +belongs + subpool to a pool 13.11.4(20/3) +bibliography 1.2(1/3) +big endian 13.5.3(2) +binary + literal 2.4.2(1) + in Interfaces.COBOL B.4(10) +binary adding operator 4.5.3(1) +binary literal 2.4.2(1) +binary operator 4.5(9) +binary_adding_operator 4.5(4) + used 4.4(4), P +Binary_Format + in Interfaces.COBOL B.4(24) +bit field + See record_representation_clause + +13.5.1(1) + +bit ordering 13.5.3(2) +bit string + See logical operators on boolean arrays + + Suspend_Until_True D.10(10) +BMP 3.5.2(2/3), 3.5.2(3/3) +BNF (Backus-Naur Form) + complete listing P + cross reference P + notation 1.1.4(3) + under Syntax heading 1.1.2(25) +body 3.11(5), 3.11.1(1/3) + used 3.11(3), P +body_stub 10.1.3(2) + used 3.11(5), P +Body_Version attribute E.3(4) +BOM_16 + in Ada.Strings.UTF_Encoding + +A.4.11(12/3) + +BOM_16BE + in Ada.Strings.UTF_Encoding + +A.4.11(10/3) + +BOM_16LE + in Ada.Strings.UTF_Encoding + +A.4.11(11/3) + +BOM_8 + in Ada.Strings.UTF_Encoding + +A.4.11(9/3) +Boolean 3.5.3(1) + in Standard A.1(5) +boolean type 3.5.3(1) +Bounded + child of Ada.Strings A.4.4(3) +bounded error 1.1.2(31), 1.1.5(8) + cause 4.8(11.1/2), 6.2(12/3), + +4.5.1(2) + +Bit_Order + in System 13.7(15/2) +Bit_Order aspect 13.5.3(4) +Bit_Order attribute 13.5.3(4) +Bit_Order clause 13.3(7/2), 13.5.3(4) +blank + in text input for enumeration and +numeric types A.10.6(5/2) + +Blank_When_Zero + in Ada.Text_IO.Editing F.3.3(7) +block_statement 5.6(2) + used 5.1(5/2), P +blocked + [partial] D.2.1(11/3) + a task state 9(10) + during an entry call 9.5.3(19) + execution of a selective_accept + +9.7.1(16) + + on a delay_statement 9.6(21) + on an accept_statement 9.5.2(24) + waiting for activations to complete + +9.2(5) + +7.6.1(14/1), 9.4(20.1/2), 9.5.1(8), +9.8(20/3), 10.2(26), 13.9.1(9), +13.11.2(11), A.17(25/2), +A.18.2(238/3), A.18.2(239/2), +A.18.2(243/2), A.18.3(152.1/3), +A.18.3(152.2/3), A.18.3(152/2), +A.18.4(75.1/3), A.18.4(75.2/3), +A.18.7(96.13/3), A.18.7(96.14/3), +A.18.10(220/3), A.18.10(221/3), +A.18.18(68/3), A.18.18(69/3), +A.18.19(10/3), A.18.20(14/3), +A.18.21(15/3), A.18.22(12/3), +A.18.23(15/3), A.18.24(12/3), +A.18.25(14/3), C.7.1(17/3), +C.7.2(13.2/1), D.2.6(30/2), +D.3(13.1/2), E.1(10/2), E.3(6), +J.7.1(11) +Bounded_IO + child of Ada.Text_IO A.10.11(3/2) + child of Ada.Wide_Text_IO A.11(4/3) + child of Ada.Wide_Wide_Text_IO + + waiting for dependents to terminate + +A.11(4/3) + +9.3(5) + +blocked interrupt C.3(2) +blocking, potentially 9.5.1(8) + Abort_Task C.7.1(16) + delay_statement 9.6(34), D.9(5) + remote subprogram call E.4(17) + RPC operations E.5(23) + +Bounded_Priority_Queues + child of Ada.Containers A.18.31(2/3) +Bounded_Slice + in Ada.Strings.Bounded A.4.4(28.1/2), + +A.4.4(28.2/2) +Bounded_String + in Ada.Strings.Bounded A.4.4(6) + +Bounded_Synchronized_Queues + child of Ada.Containers A.18.29(2/3) +bounds + of a discrete_range 3.6.1(6) + of an array 3.6(13) + of the index range of an + +array_aggregate 4.3.3(24) + +box + compound delimiter 3.6(15) +BPH + in Ada.Characters.Latin_1 A.3.3(17) +broadcast signal + See protected object 9.4(1) + See requeue 9.5.4(1) +Broken_Bar + in Ada.Characters.Latin_1 A.3.3(21/3) +BS + in Ada.Characters.Latin_1 A.3.3(5) +budget D.14.2(14/2) +Budget_Has_Expired + in + +Ada.Execution_Time.Group_Budgets +D.14.2(9/2) +Budget_Remaining + in + +Ada.Execution_Time.Group_Budgets +D.14.2(9/2) + +Buffer_Size + in Ada.Storage_IO A.9(4) +Buffer_Type subtype of Storage_Array + in Ada.Storage_IO A.9(4) +build-in-place + See built in place +built in place 7.6(17.1/3) +by copy parameter passing 6.2(2) +by reference parameter passing 6.2(2) +by-copy type 6.2(3/3) +by-reference type 6.2(4) + atomic or volatile C.6(18) +Byte + in Interfaces.COBOL B.4(29/3) + See storage element 13.3(8) +byte sex + See ordering of storage elements in a + +word 13.5.3(5) + +Byte_Array + in Interfaces.COBOL B.4(29/3) + +C + +C + child of Interfaces B.3(4) +C interface B.3(1/3) +C standard 1.2(7/3) +C++ standard 1.2(9/3) +C_float + in Interfaces.C B.3(15) +Calendar + child of Ada 9.6(10) +call 6(2/3) + +873 13 December 2012 + +Index + + + + Ada Reference Manual — 2012 Edition + + master of 3.10.2(10.1/3) +call on a dispatching operation 3.9.2(2/3) +callable 9.9(2) +Callable attribute 9.9(2) +callable construct 6(2/3) +callable entity 6(2/3) +called partition E.4(1) +Caller attribute C.7.1(14/3) +calling convention 6.3.1(2/1), B.1(11/3) + Ada 6.3.1(3/3) + associated with a designated profile + +3.10(11) + entry 6.3.1(13) + Intrinsic 6.3.1(4) + protected 6.3.1(12) +calling partition E.4(1) +calling stub E.4(10) +CAN + in Ada.Characters.Latin_1 A.3.3(6) +Cancel_Handler + in + +Ada.Execution_Time.Group_Budgets +D.14.2(10/2) + + in Ada.Execution_Time.Timers + +D.14.1(7/2) + + in Ada.Real_Time.Timing_Events + +D.15(5/2) + +cancellation + of a delay_statement 9.6(22/3) + of an entry call 9.5.3(20) +cancellation of a remote subprogram call + +E.4(13) + +canonical form A.5.3(3) +canonical order of array components + +5.5.2(11/3) + +canonical semantics 11.6(2/3) +canonical-form representation A.5.3(10) +capacity + of a hashed map A.18.5(41/2) + of a hashed set A.18.8(63/2) + of a queue A.18.27(10/3) + of a vector A.18.2(2/2) + in Ada.Containers.Hashed_Maps + +A.18.5(8/2) + + in Ada.Containers.Hashed_Sets + +A.18.8(10/2) + + in Ada.Containers.Vectors + +A.18.2(19/2) + +Capacity_Error + in Ada.Containers A.18.1(5.1/3) +case insensitive 2.3(5/3) +case_expression 4.5.7(5/3) + used 4.5.7(2/3), P +case_expression_alternative 4.5.7(6/3) + used 4.5.7(5/3), P +case_statement 5.4(2/3) + used 5.1(5/2), P +case_statement_alternative 5.4(3) + used 5.4(2/3), P + +cast + See type conversion 4.6(1/3) + See unchecked type conversion 13.9(1) +catch (an exception) + See handle 11(1/3) +categorization aspect E.2(2/3) +categorization pragma E.2(2/3) + Remote_Call_Interface E.2.3(2) + Remote_Types E.2.2(2) + Shared_Passive E.2.1(2) +categorized library unit E.2(2/3) +category + of types 3.2(2/2), 3.4(1.1/2) +category (of types) N(4.3/2) +category determined for a formal type + +12.5(6/3) +catenation operator + See concatenation operator 4.4(1/3) + See concatenation operator 4.5.3(3) +Cause_Of_Termination + in Ada.Task_Termination C.7.3(3/2) +CCH + in Ada.Characters.Latin_1 A.3.3(18) +cease to exist + object 7.6.1(11/3), 13.11.2(10/2) + type 7.6.1(11/3) +Cedilla + in Ada.Characters.Latin_1 A.3.3(22) +Ceiling + in Ada.Containers.Ordered_Maps + +CHAR_BIT + in Interfaces.C B.3(6) +Character 3.5.2(2/3) + used 2.7(2), P + in Standard A.1(35/3) +character encoding A.4.11(46/3) +character plane 2.1(1/3) +character set 2.1(1/3) +character set standard + 16 and 32-bit 1.2(8/3) + 7-bit 1.2(2) + 8-bit 1.2(6/3) + control functions 1.2(5) +character type 3.5.2(1), N(5) +character_literal 2.5(2) + used 3.5.1(4), 4.1(2/3), 4.1.3(3), P +Character_Mapping + in Ada.Strings.Maps A.4.2(20/2) +Character_Mapping_Function + in Ada.Strings.Maps A.4.2(25) +Character_Range + in Ada.Strings.Maps A.4.2(6) +Character_Ranges + in Ada.Strings.Maps A.4.2(7) +Character_Sequence subtype of String + in Ada.Strings.Maps A.4.2(16) +Character_Set + in Ada.Strings.Maps A.4.2(4/2) + in Ada.Strings.Wide_Maps A.4.7(46/2) + in Ada.Strings.Wide_Maps.Wide_- + +A.18.6(41/2) + + in Ada.Containers.Ordered_Sets +A.18.9(51/2), A.18.9(71/2) + +Ceiling attribute A.5.3(33) +ceiling priority + of a protected object D.3(8/3) +Ceiling_Check + [partial] C.3.1(11/3), D.3(13) +Ceiling_Locking locking policy D.3(7) +Cent_Sign + in Ada.Characters.Latin_1 A.3.3(21/3) +change of representation 13.6(1/3) +char + in Interfaces.C B.3(19) +char16_array + in Interfaces.C B.3(39.5/3) +char16_nul + in Interfaces.C B.3(39.3/2) +char16_t + in Interfaces.C B.3(39.2/2) +char32_array + in Interfaces.C B.3(39.14/3) +char32_nul + in Interfaces.C B.3(39.12/2) +char32_t + in Interfaces.C B.3(39.11/2) +char_array + in Interfaces.C B.3(23/3) +char_array_access + in Interfaces.C.Strings B.3.1(4) + +Constants A.4.8(48/2) + in Interfaces.Fortran B.5(11) +Character_Set_Version + in Ada.Wide_Characters.Handling + +A.3.5(4/3) +characteristics + [partial] 3.4(7/3) +Characters + child of Ada A.3.1(2) +chars_ptr + in Interfaces.C.Strings B.3.1(5/2) +chars_ptr_array + in Interfaces.C.Strings B.3.1(6/2) +check + language-defined 11.5(2/3), 11.6(1/3) +check, language-defined + Access_Check 4.1(13), 4.1.5(8/3), + +4.6(51/3), 4.8(10.4/3) + + Accessibility_Check 3.10.2(29), + +4.6(39.1/2), 4.6(48/3), 4.8(10.1/3), +6.5(8/3), 6.5(21/3), 13.11.4(25/3), +13.11.4(26/3), E.4(18/1) + Allocation_Check 4.8(10.2/2), + +4.8(10.3/2), 4.8(10.4/3), 13.11.4(30/3) + + Ceiling_Check C.3.1(11/3), D.3(13) + controlled by assertion policy + +3.2.4(31/3), 4.6(51/3), 6.1.1(32/3), +6.1.1(33/3), 6.1.1(35/3), 7.3.2(9/3) + +Index + +13 December 2012 874 + + Ada Reference Manual — 2012 Edition + + Discriminant_Check 4.1.3(15), 4.3(6), +4.3.2(8/3), 4.6(43), 4.6(45), 4.6(51/3), +4.6(52), 4.7(4), 4.8(10/2), 6.5(5.11/3) + Division_Check 3.5.4(20), 4.5.5(22), +A.5.1(28), A.5.3(47), G.1.1(40), +G.1.2(28), K.2(202) + + Elaboration_Check 3.11(9) + Index_Check 4.1.1(7), 4.1.2(7), +4.3.3(29/3), 4.3.3(30), 4.5.3(8), +4.6(51/3), 4.7(4), 4.8(10/2) + Length_Check 4.5.1(8), 4.6(37), + +4.6(52) + +class-wide postcondition expression + +6.1.1(5/3) + +class-wide precondition expression + +6.1.1(3/3) + +class-wide type 3.4.1(4), 3.7(26) +cleanup + See finalization 7.6.1(1) +clear + execution timer object D.14.1(12/2) + group budget object D.14.2(15/2) + timing event object D.15(9/2) + in Ada.Containers.Doubly_Linked_- + + Overflow_Check 3.5.4(20), 4.4(11), +4.5.7(21/3), 5.4(13), G.2.1(11), +G.2.2(7), G.2.3(25), G.2.4(2), G.2.6(3) + +Lists A.18.3(13/2) + + in Ada.Containers.Hashed_Maps + +A.18.5(12/2) + + Partition_Check E.4(19) + Range_Check 3.2.2(11), 3.5(24), + + in Ada.Containers.Hashed_Sets + +A.18.8(14/2) + +3.5(27), 3.5(39.12/3), 3.5(39.4/3), +3.5(39.5/3), 3.5(43/3), 3.5(55/3), +3.5.5(7), 3.5.9(19), 4.2(11), 4.3.3(28), +4.5.1(8), 4.5.6(6), 4.5.6(13), 4.6(28), +4.6(38), 4.6(46), 4.6(51/3), 4.7(4), +13.13.2(35/3), A.5.2(39), A.5.3(26), +A.5.3(29), A.5.3(50), A.5.3(53), +A.5.3(59), A.5.3(62), K.2(11), +K.2(114), K.2(122), K.2(184), +K.2(220), K.2(241), K.2(41), K.2(47) + + Reserved_Check C.3.1(10/3) + Storage_Check 11.1(6), 13.3(67), +13.11(17), D.7(17/1), D.7(18/1), +D.7(19/1) + + Tag_Check 3.9.2(16), 4.6(42), 4.6(52), + +5.2(10), 6.5(8.1/3) + +checking pragmas 11.5(1/2) +child + of a library unit 10.1.1(1) +Child_Count + in Ada.Containers.Multiway_Trees + +A.18.10(46/3) + +Child_Depth + in Ada.Containers.Multiway_Trees + +A.18.10(47/3) + +choice parameter 11.2(9) +choice_expression 4.4(2.1/3) + used 3.8.1(5/3), 4.4(3.2/3), P +choice_parameter_specification 11.2(4) + used 11.2(3), P +choice_relation 4.4(2.2/3) + used 4.4(2.1/3), P +Circumflex + in Ada.Characters.Latin_1 A.3.3(12) +class + of types 3.2(2/2), 3.4(1.1/2) + See also package 7(1) + See also tag 3.9(3) +class (of types) N(6/2) +Class attribute 3.9(14), 7.3.1(9), + +J.11(2/2) + +class factory 3.9(30/2) + + in Ada.Containers.Indefinite_Holders + +A.18.18(11/3) + + in Ada.Containers.Multiway_Trees + +A.18.10(23/3) + + in Ada.Containers.Ordered_Maps + +A.18.6(11/2) + + in Ada.Containers.Ordered_Sets + +A.18.9(13/2) + + in Ada.Containers.Vectors + +A.18.2(24/2) + + in Ada.Environment_Variables + +A.17(7/2) + +cleared + termination handler C.7.3(9/2) +clock 9.6(6/3) + in Ada.Calendar 9.6(12) + in Ada.Execution_Time D.14(5/2) + in Ada.Execution_Time.Interrupts + +D.14.3(3/3) + + in Ada.Real_Time D.8(6) +clock jump D.8(32) +clock tick D.8(23) +Clock_For_Interrupts + in Ada.Execution_Time D.14(9.3/3) +Close + in Ada.Direct_IO A.8.4(8) + in Ada.Sequential_IO A.8.1(8) + in Ada.Streams.Stream_IO A.12.1(10) + in Ada.Text_IO A.10.1(11) +close result set G.2.3(5) +closed entry 9.5.3(5) + of a protected object 9.5.3(7/3) + of a task 9.5.3(6/3) +closed under derivation 3.4(28), N(6/2) +closure + downward 3.10.2(37/2) +COBOL + child of Interfaces B.4(7) +COBOL interface B.4(1/3) +COBOL standard 1.2(4/2) +COBOL_Character + in Interfaces.COBOL B.4(13) + +COBOL_To_Ada + in Interfaces.COBOL B.4(15) +code point + for characters 3.5.2(2/3) +code_statement 13.8(2) + used 5.1(4/2), P +Coding aspect 13.4(7) +coextension + of an object 3.10.2(14.4/3) +Col + in Ada.Text_IO A.10.1(37) +collection + of an access type 7.6.1(11.1/3) +colon 2.1(15/3) + in Ada.Characters.Latin_1 A.3.3(10) +column number A.10(9) +comma 2.1(15/3) + in Ada.Characters.Latin_1 A.3.3(8) +Command_Line + child of Ada A.15(3) +Command_Name + in Ada.Command_Line A.15(6) +comment 2.7(2) +comments, instructions for submission + +0.2(58/1) +Commercial_At + in Ada.Characters.Latin_1 A.3.3(10) +Communication_Error + in System.RPC E.5(5) +comparison operator + See relational operator 4.5.2(1) +compatibility + composite_constraint with an access + +subtype 3.10(15/2) + + constraint with a subtype 3.2.2(12) + delta_constraint with an ordinary fixed + +point subtype J.3(9) + + digits_constraint with a decimal fixed + +point subtype 3.5.9(18) + + digits_constraint with a floating point + +subtype J.3(10) + + discriminant constraint with a subtype + +3.7.1(10) + + index constraint with a subtype 3.6.1(7) + range with a scalar subtype 3.5(8) + range_constraint with a scalar subtype + +3.5(8) +compatible + a type, with a convention B.1(12) +compilation 10.1.1(2) + separate 10.1(1) +Compilation unit 10.1(2), 10.1.1(9), N(7) +compilation units needed + by a compilation unit 10.2(2) + remote call interface E.2.3(18) + shared passive library unit E.2.1(11) +compilation_unit 10.1.1(3) + used 10.1.1(2), P +compile-time error 1.1.2(27), 1.1.5(4) +compile-time semantics 1.1.2(28) + +875 13 December 2012 + +Index + + Ada Reference Manual — 2012 Edition + +complete context 8.6(4) +completely defined 3.11.1(8) +completion + abnormal 7.6.1(2/2) + compile-time concept 3.11.1(1/3) + normal 7.6.1(2/2) + run-time concept 7.6.1(2/2) +completion and leaving (completed and + +left) 7.6.1(2/2) +completion legality + [partial] 3.10.1(13) + entry_body 9.5.2(16) +Complex + in Ada.Numerics.Generic_Complex_- + +Types G.1.1(3) + + in Interfaces.Fortran B.5(9) +Complex_Arrays + child of Ada.Numerics G.3.2(53/2) +Complex_Elementary_Functions + child of Ada.Numerics G.1.2(9/1) +Complex_IO + child of Ada.Text_IO G.1.3(3) + child of Ada.Wide_Text_IO G.1.4(1) + child of Ada.Wide_Wide_Text_IO + +G.1.5(1/2) +Complex_Matrix + in Ada.Numerics.Generic_Complex_- + +Arrays G.3.2(4/2) + +Complex_Text_IO + child of Ada G.1.3(9.1/2) +Complex_Types + child of Ada.Numerics G.1.1(25/1) +Complex_Vector + in Ada.Numerics.Generic_Complex_- + +Arrays G.3.2(4/2) + +component 3.2(2/2) + of a type 3.2(6/2) +component subtype 3.6(10) +component_choice_list 4.3.1(5) + used 4.3.1(4/2), P +component_clause 13.5.1(3) + used 13.5.1(2), P +component_declaration 3.8(6/3) + used 3.8(5/1), 9.4(6), P +component_definition 3.6(7/2) + used 3.6(3), 3.6(5), 3.8(6/3), P +component_item 3.8(5/1) + used 3.8(4), P +component_list 3.8(4) + used 3.8(3), 3.8.1(3), P +Component_Size aspect 13.3(70) +Component_Size attribute 13.3(69) +Component_Size clause 13.3(7/2), + +13.3(70) +components + of a record type 3.8(9/2) + +Compose + in Ada.Directories A.16(20/2) + in + + of an implementation with the Standard + +1.1.3(1) + + See also full conformance, mode + +Ada.Directories.Hierarchical_File_Na +mes A.16.1(14/3) + +conformance, subtype conformance, +type conformance + +Compose attribute A.5.3(24) +Compose_From_Cartesian + in Ada.Numerics.Generic_Complex_- +Arrays G.3.2(9/2), G.3.2(29/2) + in Ada.Numerics.Generic_Complex_- + +Types G.1.1(8) +Compose_From_Polar + in Ada.Numerics.Generic_Complex_- +Arrays G.3.2(11/2), G.3.2(32/2) + in Ada.Numerics.Generic_Complex_- + +Types G.1.1(11) + +composite type 3.2(2/2), N(8/2) +composite_constraint 3.2.2(7) + used 3.2.2(5), P +compound delimiter 2.2(10) +compound_statement 5.1(5/2) + used 5.1(3), P +concatenation operator 4.4(1/3), 4.5.3(3) +concrete subprogram + See nonabstract subprogram 3.9.3(1/2) +concrete type + See nonabstract type 3.9.3(1/2) +concurrent processing + See task 9(1/3) +condition 4.5.7(4/3) + used 4.5.7(3/3), 5.3(2), 5.5(3/3), 5.7(2), + +Conjugate + in Ada.Numerics.Generic_Complex_- +Arrays G.3.2(13/2), G.3.2(34/2) + in Ada.Numerics.Generic_Complex_- + +Types G.1.1(12), G.1.1(15) + +consistency + among compilation units 10.1.4(5) +constant 3.3(13/3) + result of a function_call 6.4(12/2) + See also literal 4.2(1) + See also static 4.9(1) +constant indexing 4.1.6(12/3) +constant object 3.3(13/3) +constant view 3.3(13/3) +Constant_Indexing aspect 4.1.6(2/3) +Constant_Reference + in Ada.Containers.Doubly_Linked_- + +Lists A.18.3(17.3/3) + + in Ada.Containers.Hashed_Maps +A.18.5(17.3/3), A.18.5(17.5/3) + in Ada.Containers.Hashed_Sets +A.18.8(17.2/3), A.18.8(58.3/3) + in Ada.Containers.Indefinite_Holders + + in Ada.Containers.Multiway_Trees + +A.18.18(18/3) + +A.18.10(30/3) + +9.5.2(7), 9.7.1(3), P + See also exception 11(1/3) +conditional_entry_call 9.7.3(2) + used 9.7(2), P +conditional_expression 4.5.7(2/3) + used 4.4(7/3), P +configuration + of the partitions of a program E(4) +configuration pragma 10.1.5(8) + Assertion_Policy 11.4.2(7/3) + Detect_Blocking H.5(4/2) + Discard_Names C.5(4) + Locking_Policy D.3(5) + Normalize_Scalars H.1(4) + Partition_Elaboration_Policy H.6(5/2) + Priority_Specific_Dispatching + +D.2.2(5/2) + + Profile 13.12(14/3) + Queuing_Policy D.4(5) + Restrictions 13.12(8/3) + Reviewable H.3.1(4) + Suppress 11.5(5/2) + Task_Dispatching_Policy D.2.2(5/2) + Unsuppress 11.5(5/2) +confirming + aspect specification 13.1(18.2/3) + representation item 13.1(18.2/3) + representation value 13.1(18.2/3) +conformance 6.3.1(1) + + in Ada.Containers.Ordered_Maps +A.18.6(16.3/3), A.18.6(16.5/3) + in Ada.Containers.Ordered_Sets +A.18.9(16.2/3), A.18.9(73.3/3) + + in Ada.Containers.Vectors + +A.18.2(34.3/3), A.18.2(34.5/3) + +Constant_Reference_Type + in Ada.Containers.Indefinite_Holders + +A.18.18(16/3) + + in Ada.Containers.Multiway_Trees + +A.18.10(28/3) + +Constants + child of Ada.Strings.Maps A.4.6(3/2) +constituent + of a construct 1.1.4(17) +constrained 3.2(9) + known to be 3.3(23.1/3) + object 3.3.1(9/2) + object 6.4.1(16) + subtype 3.2(9), 3.4(6), 3.5(7), +3.5.1(10), 3.5.4(9), 3.5.4(10), +3.5.7(11), 3.5.9(13), 3.5.9(16), +3.6(15), 3.6(16), 3.7(26), 3.9(15) + + subtype 3.10(14/3) + subtype K.2(33) +Constrained attribute 3.7.2(3/3), J.4(2) +constrained by its initial value 3.3.1(9/2) + [partial] 4.8(6/3), 6.5(5.11/3) +constrained_array_definition 3.6(5) + +Index + +13 December 2012 876 + + Ada Reference Manual — 2012 Edition + + used 3.6(2), P +constraint 3.2.2(5) + [partial] 3.2(7/2) + of a first array subtype 3.6(16) + of a subtype 3.2(8/2) + of an object 3.3.1(9/2) + used 3.2.2(3/2), P +Constraint_Error + raised by failure of run-time check + +Contains + in Ada.Containers.Doubly_Linked_- + +Lists A.18.3(43/2) + + in Ada.Containers.Hashed_Maps + +A.18.5(32/2) + + in Ada.Containers.Hashed_Sets +A.18.8(44/2), A.18.8(57/2) + + in Ada.Containers.Multiway_Trees + +A.18.10(41/3) + +3.2.2(12), 3.5(24), 3.5(27), +3.5(39.12/3), 3.5(39.4/3), 3.5(39.5/3), +3.5(43/3), 3.5(55/3), 3.5.4(20), +3.5.5(7), 3.5.9(19), 3.9.2(16), 4.1(13), +4.1.1(7), 4.1.2(7), 4.1.3(15), +4.1.5(8/3), 4.2(11), 4.3(6), 4.3.2(8/3), +4.3.3(31), 4.4(11), 4.5(10), 4.5(11), +4.5(12), 4.5.1(8), 4.5.3(8), 4.5.5(22), +4.5.6(6), 4.5.6(12), 4.5.6(13), +4.5.7(21/3), 4.6(28), 4.6(57/3), +4.6(60), 4.7(4), 4.8(10.4/3), 4.8(10/2), +5.2(10), 5.4(13), 6.5(5.11/3), +6.5(8.1/3), 11.1(4), 11.4.1(14/2), +11.5(10), 13.9.1(9), 13.13.2(35/3), +A.4.3(109), A.4.7(47), A.4.8(51/2), +A.5.1(28), A.5.1(34), A.5.2(39), +A.5.2(40.1/1), A.5.3(26), A.5.3(29), +A.5.3(47), A.5.3(50), A.5.3(53), +A.5.3(59), A.5.3(62), A.15(14), +B.3(53), B.3(54), B.4(58), E.4(19), +G.1.1(40), G.1.2(28), G.2.1(12), +G.2.2(7), G.2.3(26), G.2.4(3), +G.2.6(4), K.2(11), K.2(114), K.2(122), +K.2(184), K.2(202), K.2(220), +K.2(241), K.2(261), K.2(41), K.2(47) + + in Ada.Containers.Ordered_Maps + +A.18.6(42/2) + + in Ada.Containers.Ordered_Sets +A.18.9(52/2), A.18.9(72/2) + in Ada.Containers.Vectors + +A.18.2(71/2) +context free grammar + complete listing P + cross reference P + notation 1.1.4(3) + under Syntax heading 1.1.2(25) +context_clause 10.1.2(2) + used 10.1.1(3), P +context_item 10.1.2(3) + used 10.1.2(2), P +contiguous representation + [partial] 13.5.2(5), 13.7.1(12), 13.9(9), + +13.9(17/3), 13.11(21.6/3) + +Continue + in Ada.Asynchronous_Task_Control + +D.11(3/2) +control character + a category of Character A.3.2(22) + a category of Character A.3.3(4), + +A.3.3(15) + + in Standard A.1(46) +Construct 1.1.4(16), N(9) +constructor + See initialization 3.3.1(18/2) + See initialization 7.6(1) + See initialization expression 3.3.1(4) + See Initialize 7.6(1) + See initialized allocator 4.8(4) +container N(9.1/3) + cursor A.18(2/2) + list A.18.3(1/2) + map A.18.4(1/2) + set A.18.7(1/2) + vector A.18.2(1/2) +container element iterator 5.5.2(3/3) +Containers + child of Ada A.18.1(3/2) +Containing_Directory + in Ada.Directories A.16(17/2) + in + +Ada.Directories.Hierarchical_File_Na +mes A.16.1(11/3) + + See also format_effector 2.1(13/3) +Control_Set + in Ada.Strings.Maps.Constants + +A.4.6(4) + +Controlled + in Ada.Finalization 7.6(5/2) +controlled type 7.6(2), 7.6(9/2), N(10) +controlling access result 3.9.2(2/3) +controlling formal parameter 3.9.2(2/3) +controlling operand 3.9.2(2/3) +controlling result 3.9.2(2/3) +controlling tag + for a call on a dispatching operation + +3.9.2(1/2) + +controlling tag value 3.9.2(14) + for the expression in an + +assignment_statement 5.2(9) + +controlling type + of a + +formal_abstract_subprogram_declarati +on 12.6(8.4/3) + +convention 6.3.1(2/1), B.1(11/3) +Convention aspect B.1(2/3) +Convention pragma J.15.5(4/3), L(8.1/3) +conversion 4.6(1/3), 4.6(28) + + access 4.6(24.11/2), 4.6(24.18/2), + +4.6(24.19/2), 4.6(47) + arbitrary order 1.1.4(18) + array 4.6(24.2/2), 4.6(36) + composite (non-array) 4.6(21/3), + +4.6(40) + + enumeration 4.6(21.1/2), 4.6(34) + numeric 4.6(24.1/2), 4.6(29) + unchecked 13.9(1) + value 4.6(5/2) + view 4.6(5/2) +Conversion_Error + in Interfaces.COBOL B.4(30) +Conversions + child of Ada.Characters A.3.4(2/2) + child of Ada.Strings.UTF_Encoding + +A.4.11(15/3) + +Convert + in + +Ada.Strings.UTF_Encoding.Conversio +ns A.4.11(16/3), A.4.11(17/3), +A.4.11(18/3), A.4.11(19/3), +A.4.11(20/3) +convertible 4.6(4/3) + required 4.6(24.13/2), 4.6(24.4/2), + +8.6(27.1/3) + +Copy + in Ada.Containers.Doubly_Linked_- + +Lists A.18.3(17.6/3) + + in Ada.Containers.Hashed_Maps + +A.18.5(17.8/3) + + in Ada.Containers.Hashed_Sets + +A.18.8(17.4/3) + + in Ada.Containers.Indefinite_Holders + +A.18.18(21/3), A.18.20(10/3), +A.18.21(13/3), A.18.22(10/3), +A.18.23(13/3), A.18.24(10/3) + in Ada.Containers.Multiway_Trees + +A.18.10(33/3) + + in Ada.Containers.Ordered_Maps + +A.18.6(16.8/3) + + in Ada.Containers.Ordered_Sets + +A.18.9(16.4/3) + + in Ada.Containers.Vectors + +A.18.2(34.8/3) + +copy back of parameters 6.4.1(17) +copy parameter passing 6.2(2) +Copy_Array + in Interfaces.C.Pointers B.3.2(15) +Copy_File + in Ada.Directories A.16(13/2) +Copy_Sign attribute A.5.3(51) +Copy_Subtree + in Ada.Containers.Multiway_Trees + +A.18.10(54/3) + +Copy_Terminated_Array + in Interfaces.C.Pointers B.3.2(14) +Copyright_Sign + in Ada.Characters.Latin_1 A.3.3(21/3) +core language 1.1.2(2) + +877 13 December 2012 + +Index + + Ada Reference Manual — 2012 Edition + +corresponding constraint 3.4(6) +corresponding discriminants 3.7(18) +corresponding index + for an array_aggregate 4.3.3(8) +corresponding subtype 3.4(18/3) +corresponding value + of the target type of a conversion + +4.6(28) + +Cos + in Ada.Numerics.Generic_Complex_- +Elementary_Functions G.1.2(4) + in Ada.Numerics.Generic_Elementary_- + +Functions A.5.1(5) + +Cosh + in Ada.Numerics.Generic_Complex_- +Elementary_Functions G.1.2(6) + in Ada.Numerics.Generic_Elementary_- + +Functions A.5.1(7) + +Cot + in Ada.Numerics.Generic_Complex_- +Elementary_Functions G.1.2(4) + in Ada.Numerics.Generic_Elementary_- + +Functions A.5.1(5) + +Coth + in Ada.Numerics.Generic_Complex_- +Elementary_Functions G.1.2(6) + in Ada.Numerics.Generic_Elementary_- + +Functions A.5.1(7) + +Count + in Ada.Direct_IO A.8.4(4) + in Ada.Streams.Stream_IO A.12.1(7) + in Ada.Strings.Bounded A.4.4(48), + +A.4.4(49), A.4.4(50) + + in Ada.Strings.Fixed A.4.3(13), + +A.4.3(14), A.4.3(15) + + in Ada.Strings.Unbounded A.4.5(43), + +A.4.5(44), A.4.5(45) + in Ada.Text_IO A.10.1(5) +Count attribute 9.9(5) +Count_Type + in Ada.Containers A.18.1(5/2) +Country + in Ada.Locales A.19(6/3) +Country code standard 1.2(4.1/3) +Country_Code + in Ada.Locales A.19(4/3) +Country_Unknown + in Ada.Locales A.19(5/3) +cover + a type 3.4.1(9) + of a choice and an exception 11.2(6) +cover a value + by a discrete_choice 3.8.1(9) + by a discrete_choice_list 3.8.1(13) +CPU aspect D.16(8/3) +CPU clock tick D.14(15/2) +CPU pragma J.15.9(2/3), L(8.2/3) +CPU subtype of CPU_Range + in System.Multiprocessors D.16(4/3) + +CPU time + of a task D.14(11/3) +CPU_Range + in System.Multiprocessors D.16(4/3) +CPU_Tick + in Ada.Execution_Time D.14(4/2) +CPU_Time + in Ada.Execution_Time D.14(4/2) +CPU_Time_First + in Ada.Execution_Time D.14(4/2) +CPU_Time_Last + in Ada.Execution_Time D.14(4/2) +CPU_Time_Unit + in Ada.Execution_Time D.14(4/2) +CR + in Ada.Characters.Latin_1 A.3.3(5) +create 3.1(12) + in Ada.Direct_IO A.8.4(6) + in Ada.Sequential_IO A.8.1(6) + in Ada.Streams.Stream_IO A.12.1(8) + in Ada.Text_IO A.10.1(9) + in + +System.Multiprocessors.Dispatching_ +Domains D.16.1(7/3) + +Create_Directory + in Ada.Directories A.16(7/2) +Create_Path + in Ada.Directories A.16(9/2) +Create_Subpool + in System.Storage_Pools.Subpools + +13.11.4(7/3) + +creation + of a protected object C.3.1(10/3) + of a return object 6.5(5.11/3) + of a tag 13.14(20/2) + of a task object D.1(17/3) + of an object 3.3(1) +critical section + See intertask communication 9.5(1) +CSI + in Ada.Characters.Latin_1 A.3.3(19) +Currency_Sign + in Ada.Characters.Latin_1 A.3.3(21/3) +current column number A.10(9) +current index + of an open direct file A.8(4) + of an open stream file A.12.1(1.1/1) +current instance + of a generic unit 8.6(18) + of a type 8.6(17/3) +current line number A.10(9) +current mode + of an open file A.7(7) +current page number A.10(9) +Current size + of a stream file A.12.1(1.1/1) + of an external file A.8(3) +Current_Directory + in Ada.Directories A.16(5/2) + +Current_Error + in Ada.Text_IO A.10.1(17), A.10.1(20) +Current_Handler + in + +Ada.Execution_Time.Group_Budgets +D.14.2(10/2) + + in Ada.Execution_Time.Timers + +D.14.1(7/2) + + in Ada.Interrupts C.3.2(6) + in Ada.Real_Time.Timing_Events + +D.15(5/2) +Current_Input + in Ada.Text_IO A.10.1(17), A.10.1(20) +Current_Output + in Ada.Text_IO A.10.1(17), A.10.1(20) +Current_State + in Ada.Synchronous_Task_Control + +D.10(4) +Current_Task + in Ada.Task_Identification C.7.1(3/3) +Current_Task_Fallback_Handler + in Ada.Task_Termination C.7.3(5/2) +Current_Use + in + +Ada.Containers.Bounded_Priority_Qu +eues A.18.31(7/3) + + in + +Ada.Containers.Bounded_Synchronize +d_Queues A.18.29(6/3) + + in + +Ada.Containers.Synchronized_Queue_ +Interfaces A.18.27(7/3) + + in + +Ada.Containers.Unbounded_Priority_ +Queues A.18.30(7/3) + + in + +Ada.Containers.Unbounded_Synchron +ized_Queues A.18.28(6/3) + +cursor + ambiguous A.18.2(240/2) + for a container A.18(2/2) + invalid A.18.2(248/2), A.18.3(153/2), + +A.18.4(76/2), A.18.7(97/2), +A.18.10(222/3) + + in Ada.Containers.Doubly_Linked_- + +Lists A.18.3(7/2) + + in Ada.Containers.Hashed_Maps + +A.18.5(4/2) + + in Ada.Containers.Hashed_Sets + +A.18.8(4/2) + + in Ada.Containers.Multiway_Trees + +A.18.10(9/3) + + in Ada.Containers.Ordered_Maps + +A.18.6(5/2) + + in Ada.Containers.Ordered_Sets + +A.18.9(5/2) + + in Ada.Containers.Vectors A.18.2(9/2) + +D + +Index + +13 December 2012 878 + + + + Ada Reference Manual — 2012 Edition + +dangling references + prevention via accessibility rules + +3.10.2(3/2) + +Data_Error + in Ada.Direct_IO A.8.4(18) + in Ada.IO_Exceptions A.13(4) + in Ada.Sequential_IO A.8.1(15) + in Ada.Storage_IO A.9(9) + in Ada.Streams.Stream_IO A.12.1(26) + in Ada.Text_IO A.10.1(85) +date and time formatting standard + +1.2(5.1/2) + +Day + in Ada.Calendar 9.6(13) + in Ada.Calendar.Formatting + +9.6.1(23/2) + +Day_Count + in Ada.Calendar.Arithmetic 9.6.1(10/2) +Day_Duration subtype of Duration + in Ada.Calendar 9.6(11/2) +Day_Name + in Ada.Calendar.Formatting + +9.6.1(17/2) + +Day_Number subtype of Integer + in Ada.Calendar 9.6(11/2) +Day_of_Week + in Ada.Calendar.Formatting + +9.6.1(18/2) + + in + +DC1 + in Ada.Characters.Latin_1 A.3.3(6) +DC2 + in Ada.Characters.Latin_1 A.3.3(6) +DC3 + in Ada.Characters.Latin_1 A.3.3(6) +DC4 + in Ada.Characters.Latin_1 A.3.3(6) +DCS + in Ada.Characters.Latin_1 A.3.3(18) +Deadline subtype of Time + in Ada.Dispatching.EDF D.2.6(9/2) +Deallocate + in System.Storage_Pools 13.11(8) + in System.Storage_Pools.Subpools + +13.11.4(15/3) +Deallocate_Subpool + in System.Storage_Pools.Subpools + +13.11.4(12/3) + +deallocation of storage 13.11.2(1) +Decimal + child of Ada F.2(2) +decimal digit + a category of Character A.3.2(28) +decimal fixed point type 3.5.9(1), + +3.5.9(6) + +Decimal_Conversions + in Interfaces.COBOL B.4(31) +Decimal_Digit_Set + in Ada.Strings.Maps.Constants + +A.4.6(4) + +Decimal_Element + in Interfaces.COBOL B.4(12/3) +decimal_fixed_point_definition 3.5.9(4) + used 3.5.9(2), P +Decimal_IO + in Ada.Text_IO A.10.1(73) +decimal_literal 2.4.1(2) + used 2.4(2), P +Decimal_Output + in Ada.Text_IO.Editing F.3.3(11) +Declaration 3.1(5), 3.1(6/3), N(11) +declaration list + declarative_part 3.11(6.1/2) + package_specification 7.1(6/2) +declarative region + of a construct 8.1(1) +declarative_item 3.11(3) + used 3.11(2), P +declarative_part 3.11(2) + used 5.6(2), 6.3(2/3), 7.2(2/3), 9.1(6/3), + +9.5.2(5), P + +declare 3.1(8), 3.1(12) +declared pure 10.2.1(17/3) +Decode + in Ada.Strings.UTF_Encoding.Strings + +A.4.11(26/3), A.4.11(27/3), +A.4.11(28/3) + +Ada.Strings.UTF_Encoding.Wide_Stri +ngs A.4.11(34/3), A.4.11(35/3), +A.4.11(36/3) + + in + +Ada.Strings.UTF_Encoding.Wide_Wi +de_Strings A.4.11(42/3), +A.4.11(43/3), A.4.11(44/3) + +Decrement + in Interfaces.C.Pointers B.3.2(11/3) +deeper + accessibility level 3.10.2(3/2) + statically 3.10.2(4), 3.10.2(17) +default constant indexing function + +5.5.1(16/3) + +default cursor subtype 5.5.1(8/3) +default directory A.16(48/2) +default element subtype 5.5.1(9/3) +default entry queuing policy 9.5.3(17) +default iterator function 5.5.1(8/3) +default iterator subtype 5.5.1(8/3) +default pool 13.11.3(4.1/3) +default treatment C.3(5) +default variable indexing function + +5.5.1(21/3) + +Default_Aft + in Ada.Text_IO A.10.1(64), +A.10.1(69), A.10.1(74) + + in Ada.Text_IO.Complex_IO G.1.3(5) +Default_Base + in Ada.Text_IO A.10.1(53), A.10.1(58) +Default_Bit_Order + in System 13.7(15/2) + +Default_Component_Value aspect + +3.6(22.2/3) +Default_Currency + in Ada.Text_IO.Editing F.3.3(10) +Default_Deadline + in Ada.Dispatching.EDF D.2.6(9/2) +Default_Exp + in Ada.Text_IO A.10.1(64), +A.10.1(69), A.10.1(74) + + in Ada.Text_IO.Complex_IO G.1.3(5) +default_expression 3.7(6) + used 3.7(5/2), 3.8(6/3), 6.1(15/3), + +12.4(2/3), P + +Default_Fill + in Ada.Text_IO.Editing F.3.3(10) +Default_Fore + in Ada.Text_IO A.10.1(64), +A.10.1(69), A.10.1(74) + + in Ada.Text_IO.Complex_IO G.1.3(5) +Default_Iterator aspect 5.5.1(8/3) +Default_Modulus + in Ada.Containers.Indefinite_Holders + +A.18.21(10/3), A.18.23(10/3) + +default_name 12.6(4) + used 12.6(3/2), P +Default_Priority + in System 13.7(17) +Default_Quantum + in Ada.Dispatching.Round_Robin + +D.2.5(4/2) + +Default_Radix_Mark + in Ada.Text_IO.Editing F.3.3(10) +Default_Separator + in Ada.Text_IO.Editing F.3.3(10) +Default_Setting + in Ada.Text_IO A.10.1(80) +Default_Storage_Pool aspect + +13.11.3(5/3) + +Default_Storage_Pool pragma +13.11.3(3/3), L(8.3/3) +Default_Subpool_for_Pool + in System.Storage_Pools.Subpools + +13.11.4(13/3) + +Default_Value aspect 3.5(56.3/3) +Default_Width + in Ada.Text_IO A.10.1(53), +A.10.1(58), A.10.1(80) +deferred constant 7.4(2/3) +deferred constant declaration 3.3.1(6/3), + +7.4(2/3) + +defining name 3.1(10) +defining_character_literal 3.5.1(4) + used 3.5.1(3), P +defining_designator 6.1(6) + used 6.1(4.2/2), 12.3(2/3), P +defining_identifier 3.1(4) + +879 13 December 2012 + +Index + + Ada Reference Manual — 2012 Edition + + used 3.2.1(3/3), 3.2.2(2/3), 3.3.1(3), + + in Ada.Strings.Fixed A.4.3(29), + +3.5.1(3), 3.10.1(2/2), 5.5(4), +5.5.2(2/3), 6.1(7), 6.5(2.1/3), 7.3(2/3), +7.3(3/3), 8.5.1(2/3), 8.5.2(2/3), +9.1(2/3), 9.1(3/3), 9.1(6/3), 9.4(2/3), +9.4(3/3), 9.4(7/3), 9.5.2(2/3), 9.5.2(5), +9.5.2(8), 10.1.3(4), 10.1.3(5), +10.1.3(6), 11.2(4), 12.5(2.1/3), +12.5(2.2/3), 12.7(2/3), P +defining_identifier_list 3.3.1(3) + used 3.3.1(2/3), 3.3.2(2), 3.7(5/2), +3.8(6/3), 6.1(15/3), 11.1(2/3), +12.4(2/3), P + +defining_operator_symbol 6.1(11) + used 6.1(6), P +defining_program_unit_name 6.1(7) + used 6.1(4.1/2), 6.1(6), 7.1(3/3), +7.2(2/3), 8.5.3(2/3), 8.5.5(2/3), +12.3(2/3), P + +Definite attribute 12.5.1(23/3) +definite subtype 3.3(23/3) +definition 3.1(7) +Degree_Sign + in Ada.Characters.Latin_1 A.3.3(22) +DEL + in Ada.Characters.Latin_1 A.3.3(14) +delay_alternative 9.7.1(6) + used 9.7.1(4), 9.7.2(2), P +delay_relative_statement 9.6(4) + used 9.6(2), P +delay_statement 9.6(2) + used 5.1(4/2), 9.7.1(6), 9.7.4(4/2), P +Delay_Until_And_Set_CPU + in + +System.Multiprocessors.Dispatching_ +Domains D.16.1(14/3) +Delay_Until_And_Set_Deadline + in Ada.Dispatching.EDF D.2.6(9/2) +delay_until_statement 9.6(3) + used 9.6(2), P +Delete + in Ada.Containers.Doubly_Linked_- + +Lists A.18.3(24/2) + + in Ada.Containers.Hashed_Maps +A.18.5(25/2), A.18.5(26/2) + in Ada.Containers.Hashed_Sets +A.18.8(24/2), A.18.8(25/2), +A.18.8(55/2) + + in Ada.Containers.Ordered_Maps +A.18.6(24/2), A.18.6(25/2) + in Ada.Containers.Ordered_Sets +A.18.9(23/2), A.18.9(24/2), +A.18.9(68/2) + + in Ada.Containers.Vectors +A.18.2(50/2), A.18.2(51/2) + in Ada.Direct_IO A.8.4(8) + in Ada.Sequential_IO A.8.1(8) + in Ada.Streams.Stream_IO A.12.1(10) + in Ada.Strings.Bounded A.4.4(64), + +A.4.4(65) + +A.4.3(30) + + in Ada.Strings.Unbounded A.4.5(59), + +A.4.5(60) + + in Ada.Text_IO A.10.1(11) +Delete_Children + in Ada.Containers.Multiway_Trees + +A.18.10(53/3) +Delete_Directory + in Ada.Directories A.16(8/2) +Delete_File + in Ada.Directories A.16(11/2) +Delete_First + in Ada.Containers.Doubly_Linked_- + +Lists A.18.3(25/2) + + in Ada.Containers.Ordered_Maps + + semantic 10.1.1(26/2) +depth + accessibility level 3.10.2(3/2) + in Ada.Containers.Multiway_Trees + +A.18.10(19/3) + +depth-first order A.18.10(5/3) +Dequeue + in + +Ada.Containers.Bounded_Priority_Qu +eues A.18.31(5/3) + + in + +Ada.Containers.Bounded_Synchronize +d_Queues A.18.29(5/3) + + in + +Ada.Containers.Synchronized_Queue_ +Interfaces A.18.27(6/3) + +A.18.6(26/2) + + in + + in Ada.Containers.Ordered_Sets + +A.18.9(25/2) + +Ada.Containers.Unbounded_Priority_ +Queues A.18.30(5/3) + + in Ada.Containers.Vectors + + in + +A.18.2(52/2) + +Delete_Last + in Ada.Containers.Doubly_Linked_- + +Lists A.18.3(26/2) + + in Ada.Containers.Ordered_Maps + +A.18.6(27/2) + +Ada.Containers.Unbounded_Synchron +ized_Queues A.18.28(5/3) +Dequeue_Only_High_Priority + in + +Ada.Containers.Bounded_Priority_Qu +eues A.18.31(6/3) + + in Ada.Containers.Ordered_Sets + + in + +A.18.9(26/2) + + in Ada.Containers.Vectors + +A.18.2(53/2) + +Delete_Leaf + in Ada.Containers.Multiway_Trees + +A.18.10(35/3) + +Delete_Subtree + in Ada.Containers.Multiway_Trees + +A.18.10(36/3) + +Delete_Tree + in Ada.Directories A.16(10/2) +delimiter 2.2(8/2) +delivery + of an interrupt C.3(2) +delta + of a fixed point type 3.5.9(1) +Delta attribute 3.5.10(3) +delta_constraint J.3(2) + used 3.2.2(6), P +Denorm attribute A.5.3(9) +denormalized number A.5.3(10) +denote 8.6(16) + informal definition 3.1(8) + name used as a pragma argument + +8.6(32) + +depend on a discriminant + for a component 3.7(20) + for a constraint or + +component_definition 3.7(19) + +dependence + elaboration 10.2(9) + of a task on a master 9.3(1) + of a task on another task 9.3(4) + +Ada.Containers.Unbounded_Priority_ +Queues A.18.30(6/3) + +dereference 4.1(8) +Dereference_Error + in Interfaces.C.Strings B.3.1(12) +derivation class + for a type 3.4.1(2/2) +derived from + directly or indirectly 3.4.1(2/2) +derived type 3.4(1/2), N(13/2) + [partial] 3.4(24) +derived_type_definition 3.4(2/2) + used 3.2.1(4/2), P +descendant 10.1.1(11), N(13.1/2) + at run-time 3.9(12.3/3) + of a tree node A.18.10(4/3) + of a type 3.4.1(10/2) + of an incomplete view 7.3.1(5.2/3) + of the full view of a type 7.3.1(5.1/3) + relationship with scope 8.2(4) +Descendant_Tag + in Ada.Tags 3.9(7.1/2) +designate 3.10(1) +designated profile + of an access-to-subprogram type + +3.10(11) + + of an anonymous access type + +3.10(12/3) +designated subtype + of a named access type 3.10(10) + of an anonymous access type + +3.10(12/3) + +Index + +13 December 2012 880 + + Ada Reference Manual — 2012 Edition + +designated type + of a named access type 3.10(10) + of an anonymous access type + +3.10(12/3) +designator 6.1(5) + used 6.3(2/3), P +destructor + See finalization 7.6(1) + See finalization 7.6.1(1) +Detach_Handler + in Ada.Interrupts C.3.2(9) +Detect_Blocking pragma H.5(3/2), + +L(8.4/2) +Determinant + in Ada.Numerics.Generic_Complex_- + +directly specified + of a representation aspect of an entity + +13.1(8/3) + + of an operational aspect of an entity + +13.1(8.1/3) + +directly visible 8.3(2), 8.3(21) + within a pragma in a context_clause + +10.1.6(3) + + within a pragma that appears at the place + +of a compilation unit 10.1.6(5) + + within a use_clause in a context_clause + +10.1.6(3) + + within a with_clause 10.1.6(2/2) + within the parent_unit_name of a library + +unit 10.1.6(2/2) + +Arrays G.3.2(46/2) + + within the parent_unit_name of a + + in Ada.Numerics.Generic_Real_Arrays + +subunit 10.1.6(4) + +G.3.1(24/2) + +determined category for a formal type + +12.5(6/3) + +determines + a type by a subtype_mark 3.2.2(8) +Device_Error + in Ada.Direct_IO A.8.4(18) + in Ada.Directories A.16(43/2) + in Ada.IO_Exceptions A.13(4) + in Ada.Sequential_IO A.8.1(15) + in Ada.Streams.Stream_IO A.12.1(26) + in Ada.Text_IO A.10.1(85) +Diaeresis + in Ada.Characters.Latin_1 A.3.3(21/3) +Difference + in Ada.Calendar.Arithmetic 9.6.1(12/2) + in Ada.Containers.Hashed_Sets +A.18.8(32/2), A.18.8(33/2) + in Ada.Containers.Ordered_Sets +A.18.9(33/2), A.18.9(34/2) + +digit 2.4.1(4.1/2) + used 2.4.1(3), 2.4.2(5), P +digits + of a decimal fixed point subtype + +3.5.9(6), 3.5.10(7) + +Digits attribute 3.5.8(2/1), 3.5.10(7) +digits_constraint 3.5.9(5) + used 3.2.2(6), P +dimensionality + of an array 3.6(12) +direct access A.8(3) +direct file A.8(1/2) +Direct_IO + child of Ada A.8.4(2) +direct_name 4.1(3) + used 3.8.1(2), 4.1(2/3), 5.1(8), 9.5.2(3), + +10.2.1(4.2/2), 13.1(3), J.7(1), +L(25.2/2), P + +Direction + in Ada.Strings A.4.1(6) + +Directories + child of Ada A.16(3/2) +directory A.16(45/2) +directory entry A.16(49/2) +directory name A.16(46/2) +Directory_Entry_Type + in Ada.Directories A.16(29/2) +disabled + predicate checks 3.2.4(7/3) +Discard_Names pragma C.5(3), L(9) +discontiguous representation + [partial] 13.5.2(5), 13.7.1(12), 13.9(9), + +13.9(17/3), 13.11(21.6/3) +discrete array type 4.5.2(1) +discrete type 3.2(3), 3.5(1), N(14) +discrete_choice 3.8.1(5/3) + used 3.8.1(4), P +discrete_choice_list 3.8.1(4) + used 3.8.1(3), 4.3.3(5/2), 4.5.7(6/3), + +5.4(3), P +Discrete_Random + child of Ada.Numerics A.5.2(17) +discrete_range 3.6.1(3) + used 3.6.1(2), 4.1.2(2), P +discrete_subtype_definition 3.6(6) + used 3.6(5), 5.5(4), 9.5.2(2/3), 9.5.2(8), + +P + +discriminant 3.2(5/2), 3.7(1/2), N(15/2) + of a variant_part 3.8.1(6) + use in a record definition 3.8(12/3) +discriminant_association 3.7.1(3) + used 3.7.1(2), P +Discriminant_Check 11.5(12) + [partial] 4.1.3(15), 4.3(6), 4.3.2(8/3), +4.6(43), 4.6(45), 4.6(51/3), 4.6(52), +4.7(4), 4.8(10/2), 6.5(5.11/3) +discriminant_constraint 3.7.1(2) + used 3.2.2(7), P +discriminant_part 3.7(2/2) + used 3.10.1(2/2), 7.3(2/3), 7.3(3/3), + +12.5(2.1/3), 12.5(2.2/3), P + +discriminant_specification 3.7(5/2) + used 3.7(4), P + +discriminants + known 3.7(26) + unknown 3.7(26) +discriminated type 3.7(8/2) +dispatching 3.9(3) + child of Ada D.2.1(1.2/3) +dispatching call + on a dispatching operation 3.9.2(1/2) +dispatching operation 3.9.2(1/2), + +3.9.2(2/3) + [partial] 3.9(1) +dispatching point D.2.1(4/2) + [partial] D.2.3(8/2), D.2.4(9/3) +dispatching policy for tasks + [partial] D.2.1(5/2) +dispatching, task D.2.1(4/2) +Dispatching_Domain + in + +System.Multiprocessors.Dispatching_ +Domains D.16.1(5/3) +Dispatching_Domain aspect + +D.16.1(18/3) + +Dispatching_Domain pragma +J.15.10(2/3), L(9.1/3) +Dispatching_Domain_Error + in + +System.Multiprocessors.Dispatching_ +Domains D.16.1(4/3) + +Dispatching_Domains + child of System.Multiprocessors + +D.16.1(3/3) + +Dispatching_Policy_Error + in Ada.Dispatching D.2.1(1.4/3) +Display_Format + in Interfaces.COBOL B.4(22) +displayed magnitude (of a decimal value) + +disruption of an assignment 9.8(21), + +F.3.2(14) + +13.9.1(5) + + [partial] 11.6(6/3) +distinct access paths 6.2(12/3) +distributed accessibility 3.10.2(32.1/3) +distributed program E(3) +distributed system E(2) +distributed systems C(1) +divide 2.1(15/3) + in Ada.Decimal F.2(6/3) +divide operator 4.4(1/3), 4.5.5(1) +Division_Check 11.5(13/2) + [partial] 3.5.4(20), 4.5.5(22), + +A.5.1(28), A.5.3(47), G.1.1(40), +G.1.2(28), K.2(202) + +Division_Sign + in Ada.Characters.Latin_1 A.3.3(26) +DLE + in Ada.Characters.Latin_1 A.3.3(6) +Do_APC + in System.RPC E.5(10) +Do_RPC + in System.RPC E.5(9) + +881 13 December 2012 + +Index + + Ada Reference Manual — 2012 Edition + +documentation (required of an + +implementation) 1.1.3(18), M.1(1/2), +M.2(1/2), M.3(1/2) + +documentation requirements 1.1.2(34), + +Eigenvalues + in Ada.Numerics.Generic_Complex_- + +Arrays G.3.2(48/2) + + in Ada.Numerics.Generic_Real_Arrays + +M(1/3) + +G.3.1(26/2) + + summary of requirements M.1(1/2) +Dollar_Sign + in Ada.Characters.Latin_1 A.3.3(8) +dot 2.1(15/3) +dot selection + See selected_component 4.1.3(1) +double + in Interfaces.C B.3(16) +Double_Precision + in Interfaces.Fortran B.5(6) +Doubly_Linked_Lists + child of Ada.Containers A.18.3(5/3) +downward closure 3.10.2(37/2) +drift rate D.8(41) +Duration + in Standard A.1(43) +dynamic binding + See dispatching operation 3.9(1) +dynamic semantics 1.1.2(30) +Dynamic_Predicate aspect 3.2.4(1/3) +Dynamic_Priorities + child of Ada D.5.1(3/2) +dynamically determined tag 3.9.2(1/2) +dynamically enclosing + of one execution by another 11.4(2) +dynamically tagged 3.9.2(5/2) + +E + +e + in Ada.Numerics A.5(3/2) +EDF + child of Ada.Dispatching D.2.6(9/2) + child of + +Ada.Synchronous_Task_Control +D.10(5.2/3) + +EDF_Across_Priorities task dispatching + +policy D.2.6(7/2) +edited output F.3(1/2) +Editing + child of Ada.Text_IO F.3.3(3) + child of Ada.Wide_Text_IO F.3.4(1) + child of Ada.Wide_Wide_Text_IO + +F.3.5(1/2) + +effect + external 1.1.3(8) +efficiency 11.5(29), 11.6(1/3) +Eigensystem + in Ada.Numerics.Generic_Complex_- + +Arrays G.3.2(49/2) + + in Ada.Numerics.Generic_Real_Arrays + +G.3.1(27/2) + + per-object constraint 3.8(18.1/1) + pragma 2.8(12) + private_extension_declaration 7.3(17) + private_type_declaration 7.3(17) + protected declaration 9.4(12) + protected_body 9.4(15) + protected_definition 9.4(13) + range_constraint 3.5(9) + real_type_definition 3.5.6(5) + record_definition 3.8(16) + record_extension_part 3.9.1(5) + record_type_definition 3.8(16) + renaming_declaration 8.5(3) + single_protected_declaration 9.4(12) + single_task_declaration 9.1(10) + subprogram_declaration 6.1(31/2) + subtype_declaration 3.2.2(9) + subtype_indication 3.2.2(9) + task declaration 9.1(10) + task_body 9.1(13) + task_definition 9.1(11) + use_clause 8.4(12) + variant_part 3.8.1(22) +elaboration control 10.2.1(1) +elaboration dependence + library_item on another 10.2(9) +Elaboration_Check 11.5(20) + [partial] 3.11(9) +element + of a storage pool 13.11(11) + in Ada.Containers.Doubly_Linked_- + +Lists A.18.3(14/2) + + in Ada.Containers.Hashed_Maps +A.18.5(14/2), A.18.5(31/2) + in Ada.Containers.Hashed_Sets +A.18.8(15/2), A.18.8(52/2) + +Elaborate pragma 10.2.1(20), L(10) +Elaborate_All pragma 10.2.1(21), L(11) +Elaborate_Body aspect 10.2.1(26.1/3) +Elaborate_Body pragma 10.2.1(22), + +L(12) + +elaborated 3.11(8) +elaboration 3.1(11), N(15.1/2), N(19) + abstract_subprogram_declaration + +3.9.3(11.1/2) + + access_definition 3.10(17/2) + access_type_definition 3.10(16) + array_type_definition 3.6(21) + aspect_clause 13.1(19/1) + choice_parameter_specification 11.4(7) + component_declaration 3.8(17) + component_definition 3.6(22/2), + +3.8(18/2) + + component_list 3.8(17) + declaration with a True Import aspect + +B.1(38/3) + + declarative_part 3.11(7) + deferred constant declaration 7.4(10/3) + delta_constraint J.3(11) + derived_type_definition 3.4(26) + digits_constraint 3.5.9(19) + discrete_subtype_definition 3.6(22/2) + discriminant_constraint 3.7.1(12) + entry_declaration 9.5.2(22/1) + enumeration_type_definition 3.5.1(10) + exception_declaration 11.1(5) + expression_function_declaration + +6.8(8/3) + + in Ada.Containers.Indefinite_Holders + + fixed_point_definition 3.5.9(17) + floating_point_definition 3.5.7(13) + full type definition 3.2.1(11) + full_type_declaration 3.2.1(11) + generic body 12.2(2) + generic_declaration 12.1(10) + generic_instantiation 12.3(20) + incomplete_type_declaration + +3.10.1(12) + + index_constraint 3.6.1(8) + integer_type_definition 3.5.4(18) + loop_parameter_specification 5.5(9/3) + nongeneric package_body 7.2(6) + nongeneric subprogram_body 6.3(6) + null_procedure_declaration 6.7(5/3) + number_declaration 3.3.2(7) + object_declaration 3.3.1(15) + of library units for a foreign language + +main subprogram B.1(39/3) + package_body of Standard A.1(50) + package_declaration 7.1(8) + partition E.1(6) + partition E.5(21) + +A.18.18(12/3) + + in Ada.Containers.Multiway_Trees + +A.18.10(24/3) + + in Ada.Containers.Ordered_Maps +A.18.6(13/2), A.18.6(39/2) + in Ada.Containers.Ordered_Sets +A.18.9(14/2), A.18.9(65/2) + in Ada.Containers.Vectors +A.18.2(27/2), A.18.2(28/2) + + in Ada.Strings.Bounded A.4.4(26) + in Ada.Strings.Unbounded A.4.5(20) +elementary type 3.2(2/2), N(16) +Elementary_Functions + child of Ada.Numerics A.5.1(9/1) +eligible + a type, for a convention B.1(14/3) +else part + of a selective_accept 9.7.1(11) +EM + in Ada.Characters.Latin_1 A.3.3(6) +embedded systems C(1), D(1) +empty element + of a vector A.18.2(4/2) + +Index + +13 December 2012 882 + + + + Ada Reference Manual — 2012 Edition + +empty holder A.18.18(3/3) +Empty_Holder + in Ada.Containers.Indefinite_Holders + +A.18.18(7/3) + +Empty_List + in Ada.Containers.Doubly_Linked_- + +Lists A.18.3(8/2) + +Empty_Map + in Ada.Containers.Hashed_Maps + +A.18.5(5/2) + + in Ada.Containers.Ordered_Maps + +A.18.6(6/2) + +Empty_Set + in Ada.Containers.Hashed_Sets + +A.18.8(5/2) + + in Ada.Containers.Ordered_Sets + +A.18.9(6/2) + +Empty_Tree + in Ada.Containers.Multiway_Trees + +A.18.10(10/3) + +Empty_Vector + in Ada.Containers.Vectors + +A.18.2(10/2) + +enabled + invariant expression 7.3.2(21/3) + postcondition expression 6.1.1(19/3) + precondition expression 6.1.1(19/3) + predicate checks 3.2.4(7/3) +encapsulation + See package 7(1) +enclosing + immediately 8.1(13) +Encode + in Ada.Strings.UTF_Encoding.Strings + +A.4.11(23/3), A.4.11(24/3), +A.4.11(25/3) + + in + +Ada.Strings.UTF_Encoding.Wide_Stri +ngs A.4.11(31/3), A.4.11(32/3), +A.4.11(33/3) + + in + +Ada.Strings.UTF_Encoding.Wide_Wi +de_Strings A.4.11(39/3), +A.4.11(40/3), A.4.11(41/3) + +Encoding + in Ada.Strings.UTF_Encoding + +A.4.11(13/3) + +encoding scheme A.4.11(46/3) +Encoding_Error + in Ada.Strings.UTF_Encoding + +A.4.11(8/3) +Encoding_Scheme + in Ada.Strings.UTF_Encoding + +A.4.11(4/3) + +end of a line 2.2(2/3) +End_Error + raised by failure of run-time check + +13.13.2(37/1) + + in Ada.Direct_IO A.8.4(18) + in Ada.IO_Exceptions A.13(4) + + in Ada.Sequential_IO A.8.1(15) + in Ada.Streams.Stream_IO A.12.1(26) + in Ada.Text_IO A.10.1(85) +End_Of_File + in Ada.Direct_IO A.8.4(16) + in Ada.Sequential_IO A.8.1(13) + in Ada.Streams.Stream_IO A.12.1(12) + in Ada.Text_IO A.10.1(34) +End_Of_Line + in Ada.Text_IO A.10.1(30) +End_Of_Page + in Ada.Text_IO A.10.1(33) +End_Search + in Ada.Directories A.16(33/2) +endian + big 13.5.3(2) + little 13.5.3(2) +ENQ + in Ada.Characters.Latin_1 A.3.3(5) +Enqueue + in + +Ada.Containers.Bounded_Priority_Qu +eues A.18.31(5/3) + + in + +Ada.Containers.Bounded_Synchronize +d_Queues A.18.29(5/3) + + in + +Ada.Containers.Synchronized_Queue_ +Interfaces A.18.27(5/3) + + in + +Ada.Containers.Unbounded_Priority_ +Queues A.18.30(5/3) + + in + +Ada.Containers.Unbounded_Synchron +ized_Queues A.18.28(5/3) + +entity + [partial] 3.1(1) +entry + closed 9.5.3(5) + open 9.5.3(5) + single 9.5.2(20) +entry call 9.5.3(1) + simple 9.5.3(1) +entry calling convention 6.3.1(13) +entry family 9.5.2(20) +entry index subtype 3.8(18/2), 9.5.2(20) +entry queue 9.5.3(12) +entry queuing policy 9.5.3(17) + default policy 9.5.3(17) +entry_barrier 9.5.2(7) + used 9.5.2(5), P +entry_body 9.5.2(5) + used 9.4(8/1), P +entry_body_formal_part 9.5.2(6) + used 9.5.2(5), P +entry_call_alternative 9.7.2(3/2) + used 9.7.2(2), 9.7.3(2), P +entry_call_statement 9.5.3(2) + used 5.1(4/2), 9.7.2(3.1/2), P +entry_declaration 9.5.2(2/3) + + used 9.1(5/1), 9.4(5/1), P +entry_index 9.5.2(4) + used 9.5.2(3), P +entry_index_specification 9.5.2(8) + used 9.5.2(6), P +enumeration literal 3.5.1(6/3) +enumeration type 3.2(3), 3.5.1(1), N(17) +enumeration_aggregate 13.4(3) + used 13.4(2), P +Enumeration_IO + in Ada.Text_IO A.10.1(79) +enumeration_literal_specification + +3.5.1(3) + + used 3.5.1(2), P +enumeration_representation_clause + +13.4(2) + + used 13.1(2/1), P +enumeration_type_definition 3.5.1(2) + used 3.2.1(4/2), P +environment 10.1.4(1) +environment declarative_part 10.1.4(1) + for the environment task of a partition + +10.2(13) + +environment task 10.2(8) +environment variable A.17(1/2) +Environment_Task + in Ada.Task_Identification C.7.1(3/3) +Environment_Variables + child of Ada A.17(3/2) +EOT + in Ada.Characters.Latin_1 A.3.3(5) +EPA + in Ada.Characters.Latin_1 A.3.3(18) +epoch D.8(19) +equal operator 4.4(1/3), 4.5.2(1) +Equal_Case_Insensitive + child of Ada.Strings A.4.10(2/3) + child of Ada.Strings.Bounded + +A.4.10(7/3) + + child of Ada.Strings.Fixed A.4.10(5/3) + child of Ada.Strings.Unbounded + +A.4.10(10/3) + +Equal_Subtree + in Ada.Containers.Multiway_Trees + +A.18.10(14/3) + +equality operator 4.5.2(1) + special inheritance rule for tagged +types 3.4(17/2), 4.5.2(14/3) + +equals sign 2.1(15/3) +Equals_Sign + in Ada.Characters.Latin_1 A.3.3(10) +equivalent element + of a hashed set A.18.8(64/2) + of an ordered set A.18.9(78/2) +equivalent key + of a hashed map A.18.5(42/2) + of an ordered map A.18.6(55/2) + +883 13 December 2012 + +Index + + Ada Reference Manual — 2012 Edition + +Equivalent_Elements + in Ada.Containers.Hashed_Sets +A.18.8(46/2), A.18.8(47/2), +A.18.8(48/2) + + in Ada.Containers.Ordered_Sets + +A.18.9(3/2) +Equivalent_Keys + in Ada.Containers.Hashed_Maps +A.18.5(34/2), A.18.5(35/2), +A.18.5(36/2) + + in Ada.Containers.Ordered_Maps + +A.18.6(3/2) + + in Ada.Containers.Ordered_Sets + +A.18.9(63/2) +Equivalent_Sets + in Ada.Containers.Hashed_Sets + +A.18.8(8/2) + + in Ada.Containers.Ordered_Sets + +A.18.9(9/2) + +erroneous execution 1.1.2(32), 1.1.5(10) + cause 3.7.2(4), 3.9(25.3/2), 6.4.1(18/3), + +9.8(21), 9.10(11), 11.5(26), +13.3(13/3), 13.3(27), 13.3(28/2), +13.9.1(8), 13.9.1(12/3), 13.9.1(13/3), +13.11(21), 13.11.2(16/3), +13.13.2(53/2), A.10.3(22/1), +A.12.1(36.1/1), A.13(17), A.17(28/2), +A.18.2(252/2), A.18.3(157/2), +A.18.4(80/2), A.18.7(101/2), +A.18.18(70/3), A.18.19(11/3), +A.18.20(15/3), A.18.21(16/3), +A.18.22(13/3), A.18.23(16/3), +A.18.24(13/3), A.18.25(15/3), +B.1(38.1/3), B.3.1(51), B.3.1(55), +B.3.1(56), B.3.1(57), B.3.2(35), +B.3.2(36), B.3.2(37), B.3.2(38), +B.3.2(39), B.3.2(42), C.3.1(14), +C.3.1(14.1/3), C.7.1(18), C.7.2(14), +C.7.2(15), C.7.2(15.1/2), D.2.6(31/2), +D.5.1(12), D.11(9), D.14(19/2), +D.14.1(25/2), D.14.2(35/2), H.4(26), +H.4(27) + +error + compile-time 1.1.2(27), 1.1.5(4) + link-time 1.1.2(29), 1.1.5(4) + run-time 1.1.2(30), 1.1.5(6), 11.5(2/3), + +11.6(1/3) + + See also bounded error, erroneous + +execution + +ESA + in Ada.Characters.Latin_1 A.3.3(17) +ESC + in Ada.Characters.Latin_1 A.3.3(6) +Establish_RPC_Receiver + in System.RPC E.5(12) +ETB + in Ada.Characters.Latin_1 A.3.3(6) +ETX + in Ada.Characters.Latin_1 A.3.3(5) +evaluation 3.1(11), N(17.1/2), N(19) + + aggregate 4.3(5) + allocator 4.8(7/2) + array_aggregate 4.3.3(21) + attribute_reference 4.1.4(11) + case_expression 4.5.7(21/3) + concatenation 4.5.3(5) + dereference 4.1(13) + discrete_range 3.6.1(8) + extension_aggregate 4.3.2(7) + generalized_reference 4.1.5(8/3) + generic_association 12.3(21) + generic_association for a formal object + +of mode in 12.4(11) + if_expression 4.5.7(20/3) + indexed_component 4.1.1(7) + initialized allocator 4.8(7/2) + membership test 4.5.2(27/3) + name 4.1(11/2) + name that has a prefix 4.1(12) + null literal 4.2(9) + numeric literal 4.2(9) + parameter_association 6.4.1(7) + prefix 4.1(12) + primary that is a name 4.4(10) + qualified_expression 4.7(4) + quantified_expression 4.5.8(6/3) + range 3.5(9) + range_attribute_reference 4.1.4(11) + record_aggregate 4.3.1(18) + record_component_association_list + +4.3.1(19) + + selected_component 4.1.3(14) + short-circuit control form 4.5.1(7) + slice 4.1.2(7) + string_literal 4.2(10) + uninitialized allocator 4.8(8) + Val 3.5.5(7), K.2(261) + Value 3.5(55/3) + value conversion 4.6(28) + view conversion 4.6(52) + Wide_Value 3.5(43/3) + Wide_Wide_Value 3.5(39.4/3) +Exception 11(1/3), 11.1(1), N(18) +exception function 6.8(6/3) +exception occurrence 11(1/3) +exception_choice 11.2(5) + used 11.2(3), P +exception_declaration 11.1(2/3) + used 3.1(3/3), P +exception_handler 11.2(3) + used 11.2(2), P +Exception_Id + in Ada.Exceptions 11.4.1(2/2) +Exception_Identity + in Ada.Exceptions 11.4.1(5/2) +Exception_Information + in Ada.Exceptions 11.4.1(5/2) +Exception_Message + in Ada.Exceptions 11.4.1(4/3) + +Exception_Name + in Ada.Exceptions 11.4.1(2/2), + +11.4.1(5/2) + +Exception_Occurrence + in Ada.Exceptions 11.4.1(3/2) +Exception_Occurrence_Access + in Ada.Exceptions 11.4.1(3/2) +exception_renaming_declaration + +8.5.2(2/3) + used 8.5(2), P +Exceptions + child of Ada 11.4.1(2/2) +Exchange_Handler + in Ada.Interrupts C.3.2(8) +Exclamation + in Ada.Characters.Latin_1 A.3.3(8) +exclamation point 2.1(15/3) +Exclude + in Ada.Containers.Hashed_Maps + +A.18.5(24/2) + + in Ada.Containers.Hashed_Sets +A.18.8(23/2), A.18.8(54/2) + in Ada.Containers.Ordered_Maps + +A.18.6(23/2) + + in Ada.Containers.Ordered_Sets +A.18.9(22/2), A.18.9(67/2) + +excludes null + subtype 3.10(13.1/2) +execution 3.1(11), N(19) + abort_statement 9.8(4) + aborting the execution of a construct + +9.8(5) + + accept_statement 9.5.2(24) + Ada program 9(1/3) + assignment_statement 5.2(7), 7.6(17), + +7.6.1(12/2) + + asynchronous_select with a + +delay_statement trigger 9.7.4(7) + asynchronous_select with a procedure + +call trigger 9.7.4(6/2) + + asynchronous_select with an entry call + +trigger 9.7.4(6/2) + block_statement 5.6(5) + call on a dispatching operation + +3.9.2(14) + + call on an inherited subprogram + +3.4(27/2) + + case_statement 5.4(11/3) + conditional_entry_call 9.7.3(3) + delay_statement 9.6(20) + dynamically enclosing 11.4(2) + entry_body 9.5.2(26) + entry_call_statement 9.5.3(8) + exit_statement 5.7(5) + extended_return_statement 6.5(5.11/3) + goto_statement 5.8(5) + handled_sequence_of_statements + +11.2(10) + handler 11.4(7) + if_statement 5.3(5/3) + +Index + +13 December 2012 884 + + instance of Unchecked_Deallocation + + attribute_definition_clause name + + discriminant_association expression + +Ada Reference Manual — 2012 Edition + +7.6.1(10) + + loop_statement 5.5(7) + loop_statement with a for + +iteration_scheme 5.5(9/3) + loop_statement with a while +iteration_scheme 5.5(8) + + null_statement 5.1(13) + partition 10.2(25) + pragma 2.8(12) + program 10.2(25) + protected subprogram call 9.5.1(3) + raise_statement with an + +exception_name 11.3(4/2) + re-raise statement 11.3(4/2) + remote subprogram call E.4(9) + requeue protected entry 9.5.4(9) + requeue task entry 9.5.4(8) + requeue_statement 9.5.4(7/3) + selective_accept 9.7.1(15) + sequence_of_statements 5.1(15) + simple_return_statement 6.5(6/2) + subprogram call 6.4(10/2) + subprogram_body 6.3(7) + task 9.2(1) + task_body 9.2(1) + timed_entry_call 9.7.2(4/2) +execution resource + associated with a protected object + +9.4(18) + + required for a task to run 9(10) +execution time + of a task D.14(11/3) +Execution_Time + child of Ada D.14(3/2) +exhaust + a budget D.14.2(14/2) +exist + cease to 7.6.1(11/3), 13.11.2(10/2) +Exists + in Ada.Directories A.16(24/2) + in Ada.Environment_Variables + +A.17(5/2) + +exit_statement 5.7(2) + used 5.1(4/2), P +Exit_Status + in Ada.Command_Line A.15(7) +Exp + in Ada.Numerics.Generic_Complex_- +Elementary_Functions G.1.2(3) + in Ada.Numerics.Generic_Elementary_- + +Functions A.5.1(4) +expanded name 4.1.3(4) +Expanded_Name + in Ada.Tags 3.9(7/2) +expected profile 8.6(26) + accept_statement entry_direct_name + +9.5.2(11) + +13.3(4) + +3.7.1(6) + + character_literal 4.2(3) + formal subprogram actual 12.6(6) + formal subprogram default_name + +12.6(5) + + Dispatching_Domains pragma +argument J.15.10(3/3) + + entry_index 9.5.2(11) + enumeration_representation_clause + + name in an aspect_specification + +expressions 13.4(4) + +13.1.1(8/3) + + expression in an aspect_specification + + subprogram_renaming_declaration + +8.5.4(3) + +13.1.1(7/3) + expression of a + +expected type 8.6(20/2) + abort_statement task_name 9.8(3) + access attribute_reference 3.10.2(2/2) + Access attribute_reference prefix + +Default_Component_Value aspect +3.6(22.4/3) + + expression of a Default_Value aspect + +3.5(56.5/3) + +3.10.2(2.3/2) + + expression of a predicate aspect + + actual parameter 6.4.1(3) + aggregate 4.3(3/2) + allocator 4.8(3/3) + array_aggregate 4.3.3(7/2) + array_aggregate component expression + +4.3.3(7/2) + +3.2.4(2/3) + + expression of expression function + +6.8(3/3) + expression of + +extended_return_statement 6.5(3/2) + expression of simple_return_statement + + array_aggregate discrete_choice + +6.5(3/2) + +4.3.3(8) + + assignment_statement expression + +5.2(4/2) + + assignment_statement variable_name + +5.2(4/2) + + Attach_Handler pragma second + +argument J.15.7(6/3) + + attribute_definition_clause expression or + + extension_aggregate 4.3.2(4/2) + extension_aggregate ancestor +expression 4.3.2(4/2) + external name J.15.5(6/3) + first_bit 13.5.1(7) + fixed point type delta 3.5.9(6) + generic formal in object actual 12.4(4) + generic formal object + +name 13.3(4) + + attribute_designator expression + +default_expression 12.4(3) + index_constraint discrete_range + +4.1.4(7) + +3.6.1(4) + + case_expression selecting_expression + + indexable_container_object_prefix + +4.5.7(15/3) + +4.1.6(11/3) + + case_expression_alternative + + indexed_component expression + +discrete_choice 4.5.7(15/3) + +4.1.1(4) + + case_statement selecting_expression + + Interrupt_Priority pragma argument + +5.4(4/3) + + case_statement_alternative +discrete_choice 5.4(4/3) + + character_literal 4.2(3) + code_statement 13.8(4) + component_clause expressions + +13.5.1(7) + + component_declaration + +default_expression 3.8(7) + + condition 4.5.7(14/3) + CPU pragma argument J.15.9(3/3) + decimal fixed point type digits 3.5.9(6) + delay_relative_statement expression + +9.6(5) + +J.15.11(5/3) + + invariant expression 7.3.2(4/3) + iterable_name 5.5.2(3/3) + iterator_name 5.5.2(3/3) + last_bit 13.5.1(7) + link name J.15.5(6/3) + linker options B.1(10.1/3) + membership test simple_expression + +4.5.2(3/3) + + modular_type_definition expression + +3.5.4(5) + + name in an aspect_specification + +13.1.1(7/3) + + number_declaration expression + + delay_until_statement expression + +3.3.2(3) + +9.6(5) + + delta_constraint expression J.3(3) + dependent_expression 4.5.7(8/3) + dereference name 4.1(8) + discrete_subtype_definition range + + object in an aspect_specification + +13.1.1(6/3) + + object_declaration initialization + +expression 3.3.1(4) + + parameter default_expression 6.1(17) + position 13.5.1(7) + postcondition expression 6.1.1(6/3) + + Access attribute_reference prefix + +3.6(8) + +3.10.2(2.3/2) + + discriminant default_expression 3.7(7) + +885 13 December 2012 + +Index + + Ada Reference Manual — 2012 Edition + + precondition expression 6.1.1(6/3) + Priority pragma argument J.15.11(5/3) + quantified_expression 4.5.8(5/3) + range simple_expressions 3.5(5) + range_attribute_designator expression + +4.1.4(7) + + range_constraint range 3.5(5) + real_range_specification bounds + +3.5.7(5) + + record_aggregate 4.3.1(8/2) + record_component_association + +expression 4.3.1(10) + + reference_object_name 4.1.5(5/3) + Relative_Deadline pragma argument + +J.15.12(3/3) + + requested decimal precision 3.5.7(4) + restriction parameter expression + +13.12(5) + + selecting_expression case_expression + +4.5.7(15/3) + + selecting_expression case_statement + +5.4(4/3) + + short-circuit control form relation + +4.5.1(1) + + signed_integer_type_definition +simple_expression 3.5.4(5) + slice discrete_range 4.1.2(4) + Storage_Size pragma argument + +J.15.4(4/3) + + string_literal 4.2(4) + subpool_handle_name 4.8(3/3) + type_conversion operand 4.6(6) + variant_part discrete_choice 3.8.1(6) +expiration time + [partial] 9.6(1) + for a delay_relative_statement 9.6(20) + for a delay_until_statement 9.6(20) +expires + execution timer D.14.1(15/3) +explicit declaration 3.1(5), N(11) +explicit initial value 3.3.1(1/3) +explicit_actual_parameter 6.4(6) + used 6.4(5), P +explicit_dereference 4.1(5) + used 4.1(2/3), P +explicit_generic_actual_parameter + +12.3(5) + + used 12.3(4), P +explicitly aliased parameter 6.1(23.1/3) +explicitly assign 10.2(2) +explicitly limited record 3.8(13.1/3) +exponent 2.4.1(4), 4.5.6(11/3) + used 2.4.1(2), 2.4.2(2), P +Exponent attribute A.5.3(18) +exponentiation operator 4.4(1/3), 4.5.6(7) +Export aspect B.1(1/3) +Export pragma J.15.5(3/3), L(13.1/3) +exported entity B.1(23/3) +expression 4.4(1/3), 4.4(2) + predicate-static 3.2.4(15/3) + + used 2.8(3/3), 3.3.1(2/3), 3.3.2(2), + +F + +3.5.4(4), 3.5.7(2), 3.5.9(3), 3.5.9(4), +3.5.9(5), 3.7(6), 3.7.1(3), 4.1.1(2), +4.1.4(3/2), 4.1.4(5), 4.3.1(4/2), +4.3.2(3), 4.3.3(3/2), 4.3.3(5/2), +4.4(7/3), 4.5.7(3/3), 4.5.7(4/3), +4.5.7(5/3), 4.5.7(6/3), 4.5.8(3/3), +4.6(2), 4.7(2), 5.2(2), 5.4(2/3), 6.4(6), +6.5(2.1/3), 6.5(2/2), 6.8(2/3), 9.5.2(4), +9.6(3), 9.6(4), 11.3(2/2), 11.4.2(3/2), +12.3(5), 13.1.1(4/3), 13.3(2), +13.5.1(4), 13.12(4.1/2), B.1(8), +B.1(10.1/3), D.2.2(3.2/2), J.3(2), +J.7(1), J.8(1), J.15.4(2/3), J.15.5(2/3), +J.15.5(3/3), J.15.7(4/3), J.15.9(2/3), +L(2.1/2), L(6.1/3), L(8.2/3), L(13.1/3), +L(14.1/3), L(19), L(27.2/2), L(35.1/3), +P + +expression_function_declaration 6.8(2/3) + used 3.1(3/3), P +extended_digit 2.4.2(5) + used 2.4.2(4), P +Extended_Index subtype of +Index_Type'Base + + in Ada.Containers.Vectors A.18.2(7/2) +extended_return_object_declaration + +6.5(2.1/3) + + used 6.5(2.2/3), P +extended_return_statement 6.5(2.2/3) + used 5.1(5/2), P +extension + of a private type 3.9(2.1/2), 3.9.1(1/2) + of a record type 3.9(2.1/2), 3.9.1(1/2) + of a type 3.9(2/2), 3.9.1(1/2) + in Ada.Directories A.16(18/2) +extension_aggregate 4.3.2(2) + used 4.3(2), P +external call 9.5(4/3) +external effect + of the execution of an Ada program + +1.1.3(8) + + volatile/atomic objects C.6(20) +external file A.7(1) +external interaction 1.1.3(8) +external name B.1(34) +external requeue 9.5(7) +external streaming + type supports 13.13.2(52/3) +External_Name aspect B.1(1/3) +External_Tag + in Ada.Tags 3.9(7/2) +External_Tag aspect 13.3(75/3), K.2(65) +External_Tag attribute 13.3(75/3) +External_Tag clause 13.3(7/2), + +13.3(75/3), K.2(65) + +extra permission to avoid raising + +factor 4.4(6) + used 4.4(5), P +factory 3.9(30/2) +failure + of a language-defined check 11.5(2/3) + in Ada.Command_Line A.15(8) +fall-back handler C.7.3(9/2) +False 3.5.3(1) +family + entry 9.5.2(20) +Feminine_Ordinal_Indicator + in Ada.Characters.Latin_1 A.3.3(21/3) +FF + in Ada.Characters.Latin_1 A.3.3(5) +Field subtype of Integer + in Ada.Text_IO A.10.1(6) +FIFO_Queuing queuing policy D.4(7/2) +FIFO_Within_Priorities task dispatching + +policy D.2.3(2/2) + +file + as file object A.7(2/3) +file name A.16(46/2) +file terminator A.10(7) +File_Access + in Ada.Text_IO A.10.1(18) +File_Kind + in Ada.Directories A.16(22/2) +File_Mode + in Ada.Direct_IO A.8.4(4) + in Ada.Sequential_IO A.8.1(4) + in Ada.Streams.Stream_IO A.12.1(6) + in Ada.Text_IO A.10.1(4) +File_Size + in Ada.Directories A.16(23/2) +File_Type + in Ada.Direct_IO A.8.4(3) + in Ada.Sequential_IO A.8.1(3) + in Ada.Streams.Stream_IO A.12.1(5) + in Ada.Text_IO A.10.1(3) +Filter_Type + in Ada.Directories A.16(30/2) +finalization + of a master 7.6.1(4) + of a protected object 9.4(20) + of a protected object C.3.1(12/3) + of a task object J.7.1(8) + of an object 7.6.1(5) + of environment task for a foreign + +language main subprogram B.1(39/3) + + child of Ada 7.6(4/3) +Finalize 7.6(2) + in Ada.Finalization 7.6(6/2), 7.6(8/2) +Find + in Ada.Containers.Doubly_Linked_- + +exceptions 11.6(5) + +Lists A.18.3(41/2) + +extra permission to reorder actions + +11.6(6/3) + + in Ada.Containers.Hashed_Maps + +A.18.5(30/2) + +Index + +13 December 2012 886 + + + + in Ada.Containers.Hashed_Sets +A.18.8(43/2), A.18.8(56/2) + +First_Element + in Ada.Containers.Doubly_Linked_- + + in Ada.Containers.Multiway_Trees + +Lists A.18.3(34/2) + +A.18.10(38/3) + + in Ada.Containers.Ordered_Maps + + in Ada.Containers.Ordered_Maps + +A.18.6(29/2) + +Ada Reference Manual — 2012 Edition + +formal parameter + of a subprogram 6.1(17) +formal subprogram, generic 12.6(1) +formal subtype 12.5(5) +formal type 12.5(5) +formal_abstract_subprogram_declaration + +12.6(2.2/3) + used 12.6(2/2), P +formal_access_type_definition 12.5.4(2) + used 12.5(3/2), P +formal_array_type_definition 12.5.3(2) + used 12.5(3/2), P +formal_complete_type_declaration + +12.5(2.1/3) + used 12.5(2/3), P +formal_concrete_subprogram_declaration + + 12.6(2.1/3) + used 12.6(2/2), P +formal_decimal_fixed_point_definition + +12.5.2(7) + + used 12.5(3/2), P +formal_derived_type_definition + +12.5.1(3/2) + used 12.5(3/2), P +formal_discrete_type_definition + +12.5.2(2) + + used 12.5(3/2), P +formal_floating_point_definition + +12.5.2(5) + + used 12.5(3/2), P +formal_incomplete_type_declaration + +12.5(2.2/3) + used 12.5(2/3), P +formal_interface_type_definition + +12.5.5(2/2) + used 12.5(3/2), P +formal_modular_type_definition + +12.5.2(4) + + used 12.5(3/2), P +formal_object_declaration 12.4(2/3) + used 12.1(6), P +formal_ordinary_fixed_point_definition + + in Ada.Containers.Ordered_Sets + +A.18.9(42/2) + + in Ada.Containers.Vectors + +A.18.2(59/2) + +First_Index + in Ada.Containers.Vectors + +A.18.2(57/2) + +First_Key + in Ada.Containers.Ordered_Maps + +A.18.6(30/2) + +First_Valid attribute 3.5.5(7.2/3) +Fixed + child of Ada.Strings A.4.3(5) +fixed point type 3.5.9(1) +Fixed_IO + in Ada.Text_IO A.10.1(68) +fixed_point_definition 3.5.9(2) + used 3.5.6(2), P +Float 3.5.7(12), 3.5.7(14) + in Standard A.1(21) +Float_IO + in Ada.Text_IO A.10.1(63) +Float_Random + child of Ada.Numerics A.5.2(5) +Float_Text_IO + child of Ada A.10.9(33) +Float_Wide_Text_IO + child of Ada A.11(2/2) +Float_Wide_Wide_Text_IO + child of Ada A.11(3/2) +Floating + in Interfaces.COBOL B.4(9) +floating point type 3.5.7(1) +floating_point_definition 3.5.7(2) + used 3.5.6(2), P +Floor + in Ada.Containers.Ordered_Maps + +A.18.6(40/2) + +12.5.2(6) + + in Ada.Containers.Ordered_Sets +A.18.9(50/2), A.18.9(70/2) + +Floor attribute A.5.3(30) +Flush + in Ada.Streams.Stream_IO + +A.12.1(25/1) + + in Ada.Text_IO A.10.1(21/1) +Fore attribute 3.5.10(4) +form + of an external file A.7(1) + in Ada.Direct_IO A.8.4(9) + in Ada.Sequential_IO A.8.1(9) + in Ada.Streams.Stream_IO A.12.1(11) + in Ada.Text_IO A.10.1(12) +formal object, generic 12.4(1) +formal package, generic 12.7(1) + + used 12.5(3/2), P +formal_package_actual_part 12.7(3/2) + used 12.7(2/3), P +formal_package_association 12.7(3.1/2) + used 12.7(3/2), P +formal_package_declaration 12.7(2/3) + used 12.1(6), P +formal_part 6.1(14) + used 6.1(12), 6.1(13/2), P +formal_private_type_definition 12.5.1(2) + used 12.5(3/2), P +formal_signed_integer_type_definition + +12.5.2(3) + + used 12.5(3/2), P +formal_subprogram_declaration + +12.6(2/2) + used 12.1(6), P + +A.18.6(38/2) + + in Ada.Containers.Ordered_Sets +A.18.9(49/2), A.18.9(69/2) + in Ada.Containers.Vectors + +A.18.2(68/2) +Find_In_Subtree + in Ada.Containers.Multiway_Trees + +A.18.10(39/3) + +Find_Index + in Ada.Containers.Vectors + +A.18.2(67/2) + +Find_Token + in Ada.Strings.Bounded A.4.4(50.1/3), + +A.4.4(51) + + in Ada.Strings.Fixed A.4.3(15.1/3), + +A.4.3(16) + + in Ada.Strings.Unbounded +A.4.5(45.1/3), A.4.5(46) + +Fine_Delta + in System 13.7(9) +First + in Ada.Containers.Doubly_Linked_- + +Lists A.18.3(33/2) + + in Ada.Containers.Hashed_Maps + +A.18.5(27/2) + + in Ada.Containers.Hashed_Sets + +A.18.8(40/2) + + in Ada.Containers.Ordered_Maps + +A.18.6(28/2) + + in Ada.Containers.Ordered_Sets + +A.18.9(41/2) + + in Ada.Containers.Vectors + +A.18.2(58/2) + + in Ada.Iterator_Interfaces 5.5.1(3/3) +First attribute 3.5(12), 3.6.2(3) +first element + of a hashed set A.18.8(68/2) + of a set A.18.7(6/2) + of an ordered set A.18.9(81/3) +first node + of a hashed map A.18.5(46/2) + of a map A.18.4(6/2) + of an ordered map A.18.6(58/3) +first subtype 3.2.1(6), 3.4.1(5) +First(N) attribute 3.6.2(4) +first_bit 13.5.1(5) + used 13.5.1(3), P +First_Bit attribute 13.5.2(3/2) +First_Child + in Ada.Containers.Multiway_Trees + +A.18.10(60/3) +First_Child_Element + in Ada.Containers.Multiway_Trees + +A.18.10(61/3) + +887 13 December 2012 + +Index + + Ada Reference Manual — 2012 Edition + +formal_type_declaration 12.5(2/3) + used 12.1(6), P +formal_type_definition 12.5(3/2) + used 12.5(2.1/3), P +format_effector 2.1(13/3) +Formatting + child of Ada.Calendar 9.6.1(15/2) +Fortran + child of Interfaces B.5(4) +Fortran interface B.5(1/3) +Fortran standard 1.2(3/2) +Fortran_Character + in Interfaces.Fortran B.5(12/3) +Fortran_Integer + in Interfaces.Fortran B.5(5) +forward iterator 5.5.2(4/3) +Forward_Iterator + in Ada.Iterator_Interfaces 5.5.1(3/3) +Fraction attribute A.5.3(21) +Fraction_One_Half + in Ada.Characters.Latin_1 A.3.3(22) +Fraction_One_Quarter + in Ada.Characters.Latin_1 A.3.3(22) +Fraction_Three_Quarters + in Ada.Characters.Latin_1 A.3.3(22) +Free + in Ada.Strings.Unbounded A.4.5(7) + in Interfaces.C.Strings B.3.1(11) +freed + See nonexistent 13.11.2(10/2) +freeing storage 13.11.2(1) +freezing + by a constituent of a construct + +13.14(4/1) + + by an expression 13.14(8/3) + by an implicit call 13.14(8.1/3) + by an object name 13.14(8/3) + class-wide type caused by the freezing +of the specific type 13.14(15) + constituents of a full type definition + +13.14(15) + + designated subtype caused by an + +allocator 13.14(13) + + entity 13.14(2) + entity caused by a body 13.14(3/3) + entity caused by a construct 13.14(4/1) + entity caused by a name 13.14(11) + entity caused by the end of an enclosing + +construct 13.14(3/3) + + expression of an expression function by + + object_declaration 13.14(6) + profile 13.14(2.1/3) + profile of a callable entity by an +instantiation 13.14(10.2/3) + + profile of a function call 13.14(10.1/3) + specific type caused by the freezing of +the class-wide type 13.14(15) + subtype caused by a record extension + +13.14(7) + + subtype caused by an implicit +conversion 13.14(8.2/1) + subtype caused by an implicit +dereference 13.14(11.1/1) + subtypes of the profile of a callable + +entity 13.14(14/3) + + type caused by a range 13.14(12) + type caused by an expression 13.14(10) + type caused by the freezing of a + +subtype 13.14(15) + +freezing points + entity 13.14(2) +Friday + in Ada.Calendar.Formatting + +9.6.1(17/2) + +FS + in Ada.Characters.Latin_1 A.3.3(6) +full conformance + for discrete_subtype_definitions + +6.3.1(24) + + for expressions 6.3.1(19) + for known_discriminant_parts + +6.3.1(23) + + for profiles 6.3.1(18/3) + required 3.10.1(4/3), 6.3(4), 6.7(2.1/3), + +6.8(4/3), 7.3(9), 8.3(12.3/2), +8.5.4(5/3), 9.5.2(14), 9.5.2(16), +9.5.2(17), 10.1.3(11), 10.1.3(12) +full constant declaration 3.3.1(6/3) + corresponding to a formal object of + +mode in 12.4(10/2) +full declaration 7.4(2/3) +full name + of a file A.16(47/2) +full stop 2.1(15/3) +full type 3.2.1(8/2) +full type definition 3.2.1(8/2) +full view + of a type 3.2.1(8/2) +Full_Name + in Ada.Directories A.16(15/2), + +a call 13.14(10.1/3) + +A.16(39/2) + + expression of an expression function by + +Access attribute 13.14(10.3/3) + + expression of an expression function by + +an instantiation 13.14(10.2/3) + first subtype caused by the freezing of + +the type 13.14(15) + + generic_instantiation 13.14(5/3) + nominal subtype caused by a name + +Full_Stop + in Ada.Characters.Latin_1 A.3.3(8) +full_type_declaration 3.2.1(3/3) + used 3.2.1(2), P +function 6(1), N(19.1/2) + expression 6.8(6/3) + with a controlling access result + +3.9.2(2/3) + +13.14(11) + + with a controlling result 3.9.2(2/3) + +function call + master of 3.10.2(10.1/3) +function instance 12.3(13) +function_call 6.4(3) + used 4.1(2/3), P +function_specification 6.1(4.2/2) + used 6.1(4/2), 6.8(2/3), P + +G + +general access type 3.10(7/1), 3.10(8) +general_access_modifier 3.10(4) + used 3.10(3), P +generalized iterator 5.5.2(3/3) +generalized_indexing 4.1.6(10/3) + used 4.1(2/3), P +generalized_reference 4.1.5(4/3) + used 4.1(2/3), P +generation + of an interrupt C.3(2) +Generator + in Ada.Numerics.Discrete_Random + +A.5.2(19) + + in Ada.Numerics.Float_Random + +A.5.2(7) + +generic actual 12.3(7/3) +generic actual parameter 12.3(7/3) +generic actual subtype 12.5(4) +generic actual type 12.5(4) +generic body 12.2(1) +generic contract issue 10.2.1(10/2) + [partial] 3.2.4(29/3), 3.4(5.1/3), +3.7(10/3), 3.7.1(7/3), 3.9.1(3/2), +3.9.4(17/2), 3.10.2(28.1/3), +3.10.2(32/3), 4.1.6(9/3), 4.5.2(9.8/3), +4.6(24.17/3), 4.6(24.21/2), 4.8(5.6/3), +4.9(37/2), 6.5.1(6/2), 7.3(8), 8.3(26/2), +8.3.1(7/2), 8.5.1(4.6/2), 8.5.1(5/3), +8.5.4(4.3/2), 9.1(9.9/2), 9.4(11.13/2), +9.4(11.8/2), 9.5(17/3), 9.5.2(13.4/2), +10.2.1(11.7/3), 10.2.1(11/3), +10.2.1(17/3), 12.4(8.5/2), 12.6(8.3/2), +13.11.2(3.1/3), 13.11.4(23/3), +B.3.3(10/3), C.3.1(7/3), J.15.7(7/3) + +generic formal 12.1(9) +generic formal object 12.4(1) +generic formal package 12.7(1) +generic formal subprogram 12.6(1) +generic formal subtype 12.5(5) +generic formal type 12.5(5) +generic function 12.1(8/2) +generic package 12.1(8/2) +generic procedure 12.1(8/2) +generic subprogram 12.1(8/2) +generic unit 12(1), N(20) + See also dispatching operation 3.9(1) +generic_actual_part 12.3(3) + used 12.3(2/3), 12.7(3/2), P +Generic_Array_Sort + child of Ada.Containers A.18.26(3/2) + +Index + +13 December 2012 888 + + + + generic_association 12.3(4) + used 12.3(3), 12.7(3.1/2), P +Generic_Bounded_Length + in Ada.Strings.Bounded A.4.4(4) +Generic_Complex_Arrays + child of Ada.Numerics G.3.2(2/2) +Generic_Complex_Elementary_Functions + child of Ada.Numerics G.1.2(2/2) +Generic_Complex_Types + child of Ada.Numerics G.1.1(2/1) +Generic_Constrained_Array_Sort + child of Ada.Containers A.18.26(7/2) +generic_declaration 12.1(2) + used 3.1(3/3), 10.1.1(5), P +Generic_Dispatching_Constructor + child of Ada.Tags 3.9(18.2/3) +Generic_Elementary_Functions + child of Ada.Numerics A.5.1(3) +generic_formal_parameter_declaration + +12.1(6) + + used 12.1(5), P +generic_formal_part 12.1(5) + used 12.1(3/3), 12.1(4), P +generic_instantiation 12.3(2/3) + used 3.1(3/3), 10.1.1(5), P +Generic_Keys + in Ada.Containers.Hashed_Sets + +A.18.8(50/2) + + in Ada.Containers.Ordered_Sets + +A.18.9(62/2) + +generic_package_declaration 12.1(4) + used 12.1(2), P +Generic_Real_Arrays + child of Ada.Numerics G.3.1(2/2) +generic_renaming_declaration 8.5.5(2/3) + used 8.5(2), 10.1.1(6), P +Generic_Sort + child of Ada.Containers A.18.26(9.2/3) +Generic_Sorting + in Ada.Containers.Doubly_Linked_- + +Lists A.18.3(47/2) + in Ada.Containers.Vectors + +A.18.2(75/2) + +generic_subprogram_declaration + +12.1(3/3) + used 12.1(2), P +Get + in Ada.Text_IO A.10.1(41), + +A.10.1(47), A.10.1(54), A.10.1(55), +A.10.1(59), A.10.1(60), A.10.1(65), +A.10.1(67), A.10.1(70), A.10.1(72), +A.10.1(75), A.10.1(77), A.10.1(81), +A.10.1(83) + + in Ada.Text_IO.Complex_IO G.1.3(6), + +G.1.3(8) + +Get_CPU + in Ada.Interrupts C.3.2(10.1/3) + in + +System.Multiprocessors.Dispatching_ +Domains D.16.1(13/3) + +Ada Reference Manual — 2012 Edition + +Get_Deadline + in Ada.Dispatching.EDF D.2.6(9/2) +Get_Dispatching_Domain + in + +Group_Budget_Error + in + +Ada.Execution_Time.Group_Budgets +D.14.2(11/2) + +System.Multiprocessors.Dispatching_ +Domains D.16.1(10/3) + +Group_Budget_Handler + in + +Get_First_CPU + in + +System.Multiprocessors.Dispatching_ +Domains D.16.1(8/3) + +Ada.Execution_Time.Group_Budgets +D.14.2(5/2) +Group_Budgets + child of Ada.Execution_Time + +Get_Immediate + in Ada.Text_IO A.10.1(44), A.10.1(45) +Get_Last_CPU + in + +System.Multiprocessors.Dispatching_ +Domains D.16.1(9/3) + +Get_Line + in Ada.Text_IO A.10.1(49), + +A.10.1(49.1/2) + + in Ada.Text_IO.Bounded_IO +A.10.11(8/2), A.10.11(9/2), +A.10.11(10/2), A.10.11(11/2) + in Ada.Text_IO.Unbounded_IO +A.10.12(8/2), A.10.12(9/2), +A.10.12(10/2), A.10.12(11/2) + +Get_Next_Entry + in Ada.Directories A.16(35/2) +Get_Priority + in Ada.Dynamic_Priorities D.5.1(5) +global to 8.1(15) +Glossary N(1/2) +goto_statement 5.8(2) + used 5.1(4/2), P +govern a variant 3.8.1(20) +govern a variant_part 3.8.1(20) +grammar + complete listing P + cross reference P + notation 1.1.4(3) + resolution of ambiguity 8.6(3) + under Syntax heading 1.1.2(25) +graphic character + a category of Character A.3.2(23) +graphic_character 2.1(14/3) + used 2.5(2), 2.6(3), P +Graphic_Set + in Ada.Strings.Maps.Constants + +A.4.6(4) + +Grave + in Ada.Characters.Latin_1 A.3.3(13) +greater than operator 4.4(1/3), 4.5.2(1) +greater than or equal operator 4.4(1/3), + +4.5.2(1) + +greater-than sign 2.1(15/3) +Greater_Than_Sign + in Ada.Characters.Latin_1 A.3.3(10) +Group_Budget + in + +D.14.2(3/3) + +GS + in Ada.Characters.Latin_1 A.3.3(6) +guard 9.7.1(3) + used 9.7.1(2), P + +H + +handle + an exception 11(1/3), N(18) + an exception occurrence 11.4(1), + +11.4(7) + + subpool 13.11.4(18/3) +handled_sequence_of_statements 11.2(2) + used 5.6(2), 6.3(2/3), 6.5(2.2/3), + +7.2(2/3), 9.1(6/3), 9.5.2(3), 9.5.2(5), P + +handler + execution timer D.14.1(13/2) + group budget D.14.2(14/2) + interrupt C.3(2) + termination C.7.3(8/3) + timing event D.15(10/2) +Handling + child of Ada.Characters A.3.2(2/2) + child of Ada.Wide_Characters + +A.3.5(3/3) + + child of Ada.Wide_Wide_Characters + +A.3.6(1/3) +Has_Element + in Ada.Containers.Doubly_Linked_- + +Lists A.18.3(9.1/3) + + in Ada.Containers.Hashed_Maps + +A.18.5(6.1/3) + + in Ada.Containers.Hashed_Sets + +A.18.8(6.1/3) + + in Ada.Containers.Multiway_Trees + +A.18.10(12/3) + + in Ada.Containers.Ordered_Maps + +A.18.6(7.1/3) + + in Ada.Containers.Ordered_Sets + +A.18.9(7.1/3) + + in Ada.Containers.Vectors + +A.18.2(11.1/3) + +Has_Same_Storage attribute 13.3(73.2/3) +Hash + child of Ada.Strings A.4.9(2/3) + child of Ada.Strings.Bounded + +A.4.9(7/3) + + child of Ada.Strings.Unbounded + +Ada.Execution_Time.Group_Budgets +D.14.2(4/3) + +A.4.9(10/3) + +889 13 December 2012 + +Index + + + + Ada Reference Manual — 2012 Edition + +Hash_Case_Insensitive + child of Ada.Strings A.4.9(11.2/3) + child of Ada.Strings.Bounded + +A.4.9(11.7/3) + + child of Ada.Strings.Fixed + +A.4.9(11.5/3) + + child of Ada.Strings.Unbounded + +A.4.9(11.10/3) + +Hash_Type + in Ada.Containers A.18.1(4/2) +Hashed_Maps + child of Ada.Containers A.18.5(2/3) +Hashed_Sets + child of Ada.Containers A.18.8(2/3) +Head + in Ada.Strings.Bounded A.4.4(70), + +A.4.4(71) + + in Ada.Strings.Fixed A.4.3(35), + +A.4.3(36) + + in Ada.Strings.Unbounded A.4.5(65), + +A.4.5(66) + +head (of a queue) D.2.1(5/2) +heap management + user-defined 13.11(1) + See also allocator 4.8(1) +held priority D.11(4/2) +heterogeneous input-output A.12.1(1) +hexadecimal + literal 2.4.2(1) +hexadecimal digit + a category of Character A.3.2(30) +hexadecimal literal 2.4.2(1) +Hexadecimal_Digit_Set + in Ada.Strings.Maps.Constants + +A.4.6(4) + +hidden from all visibility 8.3(5), 8.3(14) + by lack of a with_clause 8.3(20/2) + for a declaration completed by a + +subsequent declaration 8.3(19) + for overridden declaration 8.3(15) + within the declaration itself 8.3(16) +hidden from direct visibility 8.3(5), + +8.3(21) + + by an inner homograph 8.3(22) + where hidden from all visibility 8.3(23) +hiding 8.3(5) +Hierarchical_File_Names + child of Ada.Directories A.16.1(3/3) +High_Order_First 13.5.3(2) + in Interfaces.COBOL B.4(25) + in System 13.7(15/2) +highest precedence operator 4.5.6(1) +highest_precedence_operator 4.5(7) +Hold + in Ada.Asynchronous_Task_Control + +D.11(3/2) + +Holder + in Ada.Containers.Indefinite_Holders + +A.18.18(6/3) +homograph 8.3(8) + +Hour + in Ada.Calendar.Formatting + +9.6.1(24/2) + +Hour_Number subtype of Natural + in Ada.Calendar.Formatting + +9.6.1(20/2) + +HT + in Ada.Characters.Latin_1 A.3.3(5) +HTJ + in Ada.Characters.Latin_1 A.3.3(17) +HTS + in Ada.Characters.Latin_1 A.3.3(17) +Hyphen + in Ada.Characters.Latin_1 A.3.3(8) +hyphen-minus 2.1(15/3) + +I + +i + in Ada.Numerics.Generic_Complex_- + +Types G.1.1(5) + + in Interfaces.Fortran B.5(10) +identifier 2.3(2/2) + used 2.8(2), 2.8(3/3), 2.8(21), 2.8(23), +3.1(4), 4.1(3), 4.1.3(3), 4.1.4(3/2), +5.5(2), 5.6(2), 6.1(5), 7.1(3/3), +7.2(2/3), 9.1(4), 9.1(6/3), 9.4(4), +9.4(7/3), 9.5.2(3), 9.5.2(5), +11.4.2(6.1/3), 11.4.2(6/2), 11.5(4.1/2), +11.5(4/2), 13.1.1(3/3), 13.1.1(4/3), +13.12(4/2), 13.12(11/3), D.2.2(3), +D.2.2(3.2/2), D.3(3), D.3(4), D.4(3), +D.4(4), H.6(3/2), J.10(3/2), +J.15.5(2/3), J.15.5(3/3), J.15.5(4/3), +L(2.2/2), L(2.3/3), L(8.1/3), L(13.1/3), +L(14.1/3), L(20), L(21), L(23), +L(25.1/2), L(27.2/2), L(27.3/3), L(29), +L(36), L(37), L(37.3/2), M.2(98), P +identifier specific to a pragma 2.8(10/3) +identifier_extend 2.3(3.1/3) + used 2.3(2/2), P +identifier_start 2.3(3/2) + used 2.3(2/2), P +Identity + in Ada.Strings.Maps A.4.2(22) + in Ada.Strings.Wide_Maps A.4.7(22) + in Ada.Strings.Wide_Wide_Maps + +A.4.8(22/2) + +Identity attribute 11.4.1(9), C.7.1(12) +idle task D.11(4/2) +if_expression 4.5.7(3/3) + used 4.5.7(2/3), P +if_statement 5.3(2) + used 5.1(5/2), P +illegal + construct 1.1.2(27) + partition 1.1.2(29) + +Im + in Ada.Numerics.Generic_Complex_- +Arrays G.3.2(7/2), G.3.2(27/2) + in Ada.Numerics.Generic_Complex_- + +Types G.1.1(6) + +image + of a value 3.5(27.3/2), 3.5(30/3), + +K.2(273/3), K.2(277.4/2) + in Ada.Calendar.Formatting +9.6.1(35/2), 9.6.1(37/2) + + in Ada.Numerics.Discrete_Random + +A.5.2(26) + + in Ada.Numerics.Float_Random + +A.5.2(14) + + in Ada.Task_Identification C.7.1(3/3) + in Ada.Text_IO.Editing F.3.3(13) +Image attribute 3.5(35) +Imaginary + in Ada.Numerics.Generic_Complex_- + +Types G.1.1(4/2) + +Imaginary subtype of Imaginary + in Interfaces.Fortran B.5(10) +immediate scope + of (a view of) an entity 8.2(11) + of a declaration 8.2(2) +Immediate_Reclamation restriction + +H.4(10) + +immediately enclosing 8.1(13) +immediately visible 8.3(4), 8.3(21) +immediately within 8.1(13) +immutably limited 7.5(8.1/3) +implementation advice 1.1.2(37) + summary of advice M.3(1/2) +implementation defined 1.1.3(18) + summary of characteristics M.2(1/2) +implementation permissions 1.1.2(36) +implementation requirements 1.1.2(33) +implementation-dependent + See unspecified 1.1.3(18) +implemented + by a protected entry 9.4(11.1/3) + by a protected subprogram 9.4(11.1/3) + by a task entry 9.1(9.2/3) +implicit conversion + legality 8.6(27.1/3) +implicit declaration 3.1(5), N(11) +implicit initial values + for a subtype 3.3.1(10) +implicit subtype conversion 4.6(59), + +4.6(60) + + Access attribute 3.10.2(30) + access discriminant 3.7(27/2) + array bounds 4.6(38) + array index 4.1.1(7) + assignment to view conversion 4.6(55) + assignment_statement 5.2(11) + bounds of a decimal fixed point type + +3.5.9(16) + + bounds of a fixed point type 3.5.9(14) + bounds of a range 3.5(9), 3.6(18) + +Index + +13 December 2012 890 + + + + Ada Reference Manual — 2012 Edition + + choices of aggregate 4.3.3(22) + component defaults 3.3.1(13/3) + default value of a scalar 3.3.1(11.1/3) + delay expression 9.6(20) + derived type discriminants 3.4(21) + discriminant values 3.7.1(12) + entry index 9.5.2(24) + expressions in aggregate 4.3.1(19) + expressions of aggregate 4.3.3(23) + function return 6.5(5.11/3), 6.5(6/2) + generic formal object of mode in + +12.4(11) + + inherited enumeration literal 3.4(29) + initialization expression 3.3.1(17) + initialization expression of allocator + +4.8(7/2) + + Interrupt_Priority aspect D.1(17/3), + +Indefinite_Hashed_Sets + child of Ada.Containers A.18.15(2/3) +Indefinite_Holders + child of Ada.Containers A.18.18(5/3) +Indefinite_Multiway_Trees + child of Ada.Containers A.18.17(2/3) +Indefinite_Ordered_Maps + child of Ada.Containers A.18.14(2/3) +Indefinite_Ordered_Sets + child of Ada.Containers A.18.16(2/3) +Indefinite_Vectors + child of Ada.Containers A.18.11(2/3) +Independent aspect C.6(6.3/3) +Independent pragma J.15.8(4/3), + +L(14.2/3) + +independent subprogram 11.6(6/3) +Independent_Components aspect + +D.3(6.1/3) + +C.6(6.9/3) + + named number value 3.3.2(6) + operand of concatenation 4.5.3(9) + parameter passing 6.4.1(10), 6.4.1(11), + +6.4.1(17) + + Priority aspect D.1(17/3), D.3(6.1/3) + qualified_expression 4.7(4) + reading a view conversion 4.6(56) + result of inherited function 3.4(27/2) +implicit_dereference 4.1(6) + used 4.1(4), P +Implicit_Dereference aspect 4.1.5(2/3) +Import aspect B.1(1/3) +Import pragma J.15.5(2/3), L(14.1/3) +imported entity B.1(23/3) +in (membership test) 4.4(1/3), 4.5.2(2/3) +inaccessible partition E.1(7) +inactive + a task state 9(10) +Include + in Ada.Containers.Hashed_Maps + +A.18.5(22/2) + + in Ada.Containers.Hashed_Sets + +A.18.8(21/2) + + in Ada.Containers.Ordered_Maps + +A.18.6(21/2) + + in Ada.Containers.Ordered_Sets + +A.18.9(20/2) + +included + one range in another 3.5(4) +incomplete type 3.2(4.1/2), 3.10.1(2.1/2), + +N(20.1/2) + +incomplete view 3.10.1(2.1/2) + tagged 3.10.1(2.1/2) +incomplete_type_declaration 3.10.1(2/2) + used 3.2.1(2), P +Increment + in Interfaces.C.Pointers B.3.2(11/3) +indefinite subtype 3.3(23/3), 3.7(26) +Indefinite_Doubly_Linked_Lists + child of Ada.Containers A.18.12(2/3) +Indefinite_Hashed_Maps + child of Ada.Containers A.18.13(2/3) + +Independent_Components pragma + +J.15.8(7/3), L(14.3/3) + +independently addressable 9.10(1/3) + specified C.6(8.1/3) +index + of an element of an open direct file + +A.8(3) + + in Ada.Direct_IO A.8.4(15) + in Ada.Streams.Stream_IO A.12.1(23) + in Ada.Strings.Bounded A.4.4(43.1/2), +A.4.4(43.2/2), A.4.4(44), A.4.4(45), +A.4.4(45.1/2), A.4.4(46) + + in Ada.Strings.Fixed A.4.3(8.1/2), +A.4.3(8.2/2), A.4.3(9), A.4.3(10), +A.4.3(10.1/2), A.4.3(11) + in Ada.Strings.Unbounded + +A.4.5(38.1/2), A.4.5(38.2/2), +A.4.5(39), A.4.5(40), A.4.5(40.1/2), +A.4.5(41) + +index range 3.6(13) +index subtype 3.6(9) +index type 3.6(9) +Index_Check 11.5(14) + [partial] 4.1.1(7), 4.1.2(7), 4.3.3(29/3), +4.3.3(30), 4.5.3(8), 4.6(51/3), 4.7(4), +4.8(10/2) + +index_constraint 3.6.1(2) + used 3.2.2(7), P +Index_Error + in Ada.Strings A.4.1(5) +Index_Non_Blank + in Ada.Strings.Bounded A.4.4(46.1/2), + +A.4.4(47) + + in Ada.Strings.Fixed A.4.3(11.1/2), + +A.4.3(12) + + in Ada.Strings.Unbounded +A.4.5(41.1/2), A.4.5(42) +index_subtype_definition 3.6(4) + used 3.6(3), P +indexable container object 4.1.6(5/3) +indexable container type 4.1.6(5/3), + +N(20.2/3) + +indexed_component 4.1.1(2) + used 4.1(2/3), P +indexing + constant 4.1.6(12/3) + variable 4.1.6(16/3) +individual membership test 4.5.2(26.1/3) +indivisible C.6(10/3) +inferable discriminants B.3.3(20/2) +Information + child of Ada.Directories A.16(124/2) +information hiding + See package 7(1) + See private types and private + +extensions 7.3(1) + +information systems C(1), F(1) +informative 1.1.2(18) +inherently mutable object 3.3(13/3) +inheritance + See derived types and classes 3.4(1/2) + See also tagged types and type + +extension 3.9(1) + +inherited + from an ancestor type 3.4.1(11) +inherited component 3.4(11), 3.4(12) +inherited discriminant 3.4(11) +inherited entry 3.4(12) +inherited protected subprogram 3.4(12) +inherited subprogram 3.4(17/2) +Initial_Directory + in + +Ada.Directories.Hierarchical_File_Na +mes A.16.1(12/3) + +initialization + of a protected object 9.4(14) + of a protected object C.3.1(10/3), + +C.3.1(11/3) + + of a task object 9.1(12/1), J.7.1(7) + of an object 3.3.1(18/2) +initialization expression 3.3.1(1/3), + +3.3.1(4) +Initialize 7.6(2) + in Ada.Finalization 7.6(6/2), 7.6(8/2) +initialized allocator 4.8(4) +initialized by default 3.3.1(18/2) +Inline aspect 6.3.2(5.1/3) +Inline pragma J.15.1(2/3), L(15.1/3) +innermost dynamically enclosing 11.4(2) +input A.6(1/2) +Input aspect 13.13.2(38/3) +Input attribute 13.13.2(22), 13.13.2(32) +Input clause 13.3(7/2), 13.13.2(38/3) +input-output + unspecified for access types A.7(6) +Insert + in Ada.Containers.Doubly_Linked_- +Lists A.18.3(19/2), A.18.3(20/2), +A.18.3(21/2) + + in Ada.Containers.Hashed_Maps +A.18.5(19/2), A.18.5(20/2), +A.18.5(21/2) + +891 13 December 2012 + +Index + + Ada Reference Manual — 2012 Edition + + in Ada.Containers.Hashed_Sets +A.18.8(19/2), A.18.8(20/2) + in Ada.Containers.Ordered_Maps +A.18.6(18/2), A.18.6(19/2), +A.18.6(20/2) + + in Ada.Containers.Ordered_Sets +A.18.9(18/2), A.18.9(19/2) + in Ada.Containers.Vectors + +A.18.2(36/2), A.18.2(37/2), +A.18.2(38/2), A.18.2(39/2), +A.18.2(40/2), A.18.2(41/2), +A.18.2(42/2), A.18.2(43/2) + + in Ada.Strings.Bounded A.4.4(60), + +A.4.4(61) + + in Ada.Strings.Fixed A.4.3(25), + +A.4.3(26) + + in Ada.Strings.Unbounded A.4.5(55), + +A.4.5(56) +Insert_Child + in Ada.Containers.Multiway_Trees +A.18.10(48/3), A.18.10(49/3), +A.18.10(50/3) + +Insert_Space + in Ada.Containers.Vectors +A.18.2(48/2), A.18.2(49/2) +inspectable object H.3.2(5/2) +inspection point H.3.2(5/2) +Inspection_Point pragma H.3.2(3), L(16) +instance + of a generic function 12.3(13) + of a generic package 12.3(13) + of a generic procedure 12.3(13) + of a generic subprogram 12.3(13) + of a generic unit 12.3(1) +instructions for comment submission + +0.2(58/1) + +int + in Interfaces.C B.3(7) +Integer 3.5.4(11), 3.5.4(21) + in Standard A.1(12) +integer literal 2.4(1) +integer literals 3.5.4(14), 3.5.4(30) +integer type 3.5.4(1), N(21) +Integer_Address + in System.Storage_Elements + +13.7.1(10/3) + +Integer_IO + in Ada.Text_IO A.10.1(52) +Integer_Text_IO + child of Ada A.10.8(21) +integer_type_definition 3.5.4(2) + used 3.2.1(4/2), P +Integer_Wide_Text_IO + child of Ada A.11(2/2) +Integer_Wide_Wide_Text_IO + child of Ada A.11(3/2) +interaction + between tasks 9(1/3) +interface 3.9.4(4/2) + limited 3.9.4(5/2) + + nonlimited 3.9.4(5/2) + protected 3.9.4(5/2) + synchronized 3.9.4(5/2) + task 3.9.4(5/2) + type 3.9.4(4/2) +interface to assembly language C.1(4/3) +interface to C B.3(1/3) +interface to COBOL B.4(1/3) +interface to Fortran B.5(1/3) +interface to other languages B(1) +interface type N(21.1/2) +Interface_Ancestor_Tags + in Ada.Tags 3.9(7.4/2) +interface_list 3.9.4(3/2) + used 3.4(2/2), 3.9.4(2/2), 7.3(3/3), + +9.1(2/3), 9.1(3/3), 9.4(2/3), 9.4(3/3), +12.5.1(3/2), P + +interface_type_definition 3.9.4(2/2) + used 3.2.1(4/2), 12.5.5(2/2), P +Interfaces B.2(3) +Interfaces.C B.3(4) +Interfaces.C.Pointers B.3.2(4) +Interfaces.C.Strings B.3.1(3) +Interfaces.COBOL B.4(7) +Interfaces.Fortran B.5(4) +interfacing aspect B.1(0.1/3) +interfacing pragma J.15.5(1/3) + Convention J.15.5(1/3) + Export J.15.5(1/3) + Import J.15.5(1/3) +internal call 9.5(3/3) +internal code 13.4(7) +internal requeue 9.5(7) +Internal_Tag + in Ada.Tags 3.9(7/2) +interpretation + of a complete context 8.6(10) + of a constituent of a complete context + +8.6(15) + + overload resolution 8.6(14) +interrupt C.3(2) + example using asynchronous_select + +9.7.4(10), 9.7.4(12) +interrupt entry J.7.1(5) +interrupt handler C.3(2) +Interrupt_Clocks_Supported + in Ada.Execution_Time D.14(9.1/3) +Interrupt_Handler aspect C.3.1(6.2/3) +Interrupt_Handler pragma J.15.7(2/3), + +L(17.1/3) +Interrupt_Id + in Ada.Interrupts C.3.2(2/3) +Interrupt_Priority aspect D.1(6.3/3) +Interrupt_Priority pragma J.15.11(4/3), + +L(18.1/3) + +Interrupt_Priority subtype of Any_Priority + in System 13.7(16) + +Interrupts + child of Ada C.3.2(2/3) + child of Ada.Execution_Time + +D.14.3(3/3) + +Intersection + in Ada.Containers.Hashed_Sets +A.18.8(29/2), A.18.8(30/2) + in Ada.Containers.Ordered_Sets +A.18.9(30/2), A.18.9(31/2) +intertask communication 9.5(1) + See also task 9(1/3) +Intrinsic calling convention 6.3.1(4) +invalid cursor + of a list container A.18.3(153/2) + of a map A.18.4(76/2) + of a set A.18.7(97/2) + of a tree A.18.10(222/3) + of a vector A.18.2(248/2) +invalid representation 13.9.1(9) +invariant N(21.2/3) +invariant check 7.3.2(9/3) +invariant expression 7.3.2(2/3) +Inverse + in Ada.Numerics.Generic_Complex_- + +Arrays G.3.2(46/2) + + in Ada.Numerics.Generic_Real_Arrays + +G.3.1(24/2) + +Inverted_Exclamation + in Ada.Characters.Latin_1 A.3.3(21/3) +Inverted_Question + in Ada.Characters.Latin_1 A.3.3(22) +involve an inner product + complex G.3.2(56/2) + real G.3.1(34/2) +IO_Exceptions + child of Ada A.13(3) +IS1 + in Ada.Characters.Latin_1 A.3.3(16) +IS2 + in Ada.Characters.Latin_1 A.3.3(16) +IS3 + in Ada.Characters.Latin_1 A.3.3(16) +IS4 + in Ada.Characters.Latin_1 A.3.3(16) +Is_A_Group_Member + in + +Ada.Execution_Time.Group_Budgets +D.14.2(8/2) + +Is_Abstract + in Ada.Tags 3.9(7.5/3) +Is_Alphanumeric + in Ada.Characters.Handling A.3.2(4/3) + in Ada.Wide_Characters.Handling + +A.3.5(12/3) + +Is_Attached + in Ada.Interrupts C.3.2(5) +Is_Basic + in Ada.Characters.Handling A.3.2(4/3) +Is_Callable + in Ada.Task_Identification C.7.1(4/3) + +Index + +13 December 2012 892 + + Ada Reference Manual — 2012 Edition + +Is_Character + in Ada.Characters.Conversions + +Is_Leaf + in Ada.Containers.Multiway_Trees + +Is_Simple_Name + in + +A.3.4(3/2) + +A.18.10(21/3) + +Is_Control + in Ada.Characters.Handling A.3.2(4/3) + in Ada.Wide_Characters.Handling + +Is_Letter + in Ada.Characters.Handling A.3.2(4/3) + in Ada.Wide_Characters.Handling + +Ada.Directories.Hierarchical_File_Na +mes A.16.1(4/3) + +Is_Sorted + in Ada.Containers.Doubly_Linked_- + +A.3.5(5/3) + +Is_Current_Directory_Name + in + +Ada.Directories.Hierarchical_File_Na +mes A.16.1(7/3) + +A.3.5(6/3) +Is_Line_Terminator + in Ada.Characters.Handling A.3.2(4/3) + in Ada.Wide_Characters.Handling + +A.3.5(14/3) + +Is_Decimal_Digit + in Ada.Characters.Handling A.3.2(4/3) + in Ada.Wide_Characters.Handling + +Is_Lower + in Ada.Characters.Handling A.3.2(4/3) + in Ada.Wide_Characters.Handling + +A.3.5(10/3) + +A.3.5(7/3) + +Lists A.18.3(48/2) + in Ada.Containers.Vectors + +A.18.2(76/2) + +Is_Space + in Ada.Characters.Handling A.3.2(4/3) + in Ada.Wide_Characters.Handling + +A.3.5(18/3) + +Is_Special + in Ada.Characters.Handling A.3.2(4/3) + in Ada.Wide_Characters.Handling + +A.3.5(13/3) + +Is_String + in Ada.Characters.Conversions + +A.3.4(3/2) + +Is_Subset + in Ada.Containers.Hashed_Sets + + in Ada.Containers.Ordered_Sets + +A.18.8(39/2) + +A.18.9(40/2) + +Is_Mark + in Ada.Characters.Handling A.3.2(4/3) + in Ada.Wide_Characters.Handling + +A.3.5(15/3) + +Is_Member + in + +Ada.Execution_Time.Group_Budgets +D.14.2(8/2) +Is_Nul_Terminated + in Interfaces.C B.3(24), B.3(35), + +B.3(39.16/2), B.3(39.7/2) + +Is_Open + in Ada.Direct_IO A.8.4(10) + in Ada.Sequential_IO A.8.1(10) + in Ada.Streams.Stream_IO A.12.1(12) + in Ada.Text_IO A.10.1(13) +Is_Other_Format + in Ada.Characters.Handling A.3.2(4/3) + in Ada.Wide_Characters.Handling + + in Ada.Strings.Maps A.4.2(14) + in Ada.Strings.Wide_Maps A.4.7(14) + in Ada.Strings.Wide_Wide_Maps + +A.4.8(14/2) +Is_Terminated + in Ada.Task_Identification C.7.1(4/3) +Is_Upper + in Ada.Characters.Handling A.3.2(4/3) + in Ada.Wide_Characters.Handling + +Is_Descendant_At_Same_Level + in Ada.Tags 3.9(7.1/2) +Is_Digit + in Ada.Characters.Handling A.3.2(4/3) + in Ada.Wide_Characters.Handling + +A.3.5(9/3) + +Is_Empty + in Ada.Containers.Doubly_Linked_- + +Lists A.18.3(12/2) + + in Ada.Containers.Hashed_Maps + +A.18.5(11/2) + + in Ada.Containers.Hashed_Sets + +A.18.8(13/2) + + in Ada.Containers.Indefinite_Holders + +A.18.18(10/3) + + in Ada.Containers.Multiway_Trees + +A.18.10(16/3) + + in Ada.Containers.Ordered_Maps + +A.18.6(10/2) + + in Ada.Containers.Ordered_Sets + +A.3.5(16/3) + +A.18.9(12/2) + + in Ada.Containers.Vectors + +Is_Parent_Directory_Name + in + +A.18.2(23/2) + +Is_Full_Name + in + +Ada.Directories.Hierarchical_File_Na +mes A.16.1(8/3) + +Ada.Directories.Hierarchical_File_Na +mes A.16.1(6/3) +Is_Punctuation_Connector + in Ada.Characters.Handling A.3.2(4/3) + in Ada.Wide_Characters.Handling + +Is_Graphic + in Ada.Characters.Handling A.3.2(4/3) + in Ada.Wide_Characters.Handling + +A.3.5(17/3) +Is_Relative_Name + in + +A.3.5(8/3) +Is_Wide_Character + in Ada.Characters.Conversions + +A.3.4(3/2) +Is_Wide_String + in Ada.Characters.Conversions + +A.3.4(3/2) + +ISO 1989:2002 1.2(4/2) +ISO 639-3:2007 1.2(1.1/3) +ISO 8601:2004 1.2(5.1/2) +ISO/IEC 10646:2011 1.2(8/3), + +A.3.5(19/3) + +Is_Held + in Ada.Asynchronous_Task_Control + +D.11(3/2) + +Is_Hexadecimal_Digit + in Ada.Characters.Handling A.3.2(4/3) + in Ada.Wide_Characters.Handling + +A.3.5(11/3) + +Is_In + in Ada.Strings.Maps A.4.2(13) + in Ada.Strings.Wide_Maps A.4.7(13) + in Ada.Strings.Wide_Wide_Maps + +A.4.8(13/2) + +Ada.Directories.Hierarchical_File_Na +mes A.16.1(9/3) + +Is_Reserved + in Ada.Interrupts C.3.2(4) +Is_Root + in Ada.Containers.Multiway_Trees + +A.18.10(20/3) + +Is_Root_Directory_Name + in + +Ada.Directories.Hierarchical_File_Na +mes A.16.1(5/3) + +Is_Round_Robin + in Ada.Dispatching.Round_Robin + +Is_ISO_646 + in Ada.Characters.Handling A.3.2(10) + +D.2.5(4/2) + +3.5.2(2/3), 3.5.2(3/3), 3.5.2(4/3) + +ISO/IEC 14882:2011 1.2(9/3) +ISO/IEC 1539-1:2004 1.2(3/2) +ISO/IEC 3166-1:2006 1.2(4.1/3) +ISO/IEC 6429:1992 1.2(5) +ISO/IEC 646:1991 1.2(2) +ISO/IEC 8859-1:1998 1.2(6/3) +ISO/IEC 9899:2011 1.2(7/3) +ISO/IEC TR 19769:2004 1.2(10/2) +ISO_646 subtype of Character + in Ada.Characters.Handling A.3.2(9) +ISO_646_Set + in Ada.Strings.Maps.Constants + +A.4.6(4) + +893 13 December 2012 + +Index + + K + +Key + in Ada.Containers.Hashed_Maps + +Last + in Ada.Containers.Doubly_Linked_- + +Lists A.18.3(35/2) + + in Ada.Containers.Ordered_Maps + +A.18.5(13/2) + +A.18.6(31/2) + + in Ada.Containers.Hashed_Sets + + in Ada.Containers.Ordered_Sets + +A.18.8(51/2) + +A.18.9(43/2) + + in Ada.Containers.Ordered_Maps + + in Ada.Containers.Vectors + +A.18.6(12/2) + +A.18.2(61/2) + +Ada Reference Manual — 2012 Edition + +issue + an entry call 9.5.3(8) +italics + nongraphic characters 3.5.2(2/3) + pseudo-names of anonymous types + +3.2.1(7/2), A.1(2) + syntax rules 1.1.4(14) + terms introduced or defined 1.3(1/2) +iterable container object 5.5.1(11/3) +iterable container object for a loop + +5.5.2(12/3) + +iterable container type 5.5.1(11/3), + +N(21.3/3) + +Iterate + in Ada.Containers.Doubly_Linked_- + +Lists A.18.3(45/2) + + in Ada.Containers.Hashed_Maps + + in Ada.Containers.Ordered_Sets + +A.18.9(64/2) + +Kind + in Ada.Directories A.16(25/2), + +A.16(40/2) + +known discriminants 3.7(26) +known to be constrained 3.3(23.1/3) +known to denote the same object + +A.18.5(37/2) + +6.4.1(6.4/3) + + in Ada.Containers.Hashed_Sets + +known to refer to the same object + +A.18.8(49/2) + +6.4.1(6.11/3) + + in Ada.Containers.Multiway_Trees +A.18.10(42/3), A.18.10(44/3) + in Ada.Containers.Ordered_Maps + +A.18.6(50/2) + + in Ada.Containers.Ordered_Sets + +A.18.9(60/2) + + in Ada.Containers.Vectors + +A.18.2(73/2) + + in Ada.Environment_Variables + +A.17(8/3) +Iterate_Children + in Ada.Containers.Multiway_Trees +A.18.10(68/3), A.18.10(70/3) + +Iterate_Subtree + in Ada.Containers.Multiway_Trees +A.18.10(43/3), A.18.10(45/3) +iteration cursor subtype 5.5.1(6/3) +iteration_scheme 5.5(3/3) + used 5.5(2), P +iterator N(21.4/3) + array component 5.5.2(3/3) + container element 5.5.2(3/3) + forward 5.5.2(4/3) + generalized 5.5.2(3/3) + reverse 5.5.2(4/3) +iterator object 5.5.1(6/3) +iterator type 5.5.1(6/3) +Iterator_Element aspect 5.5.1(9/3) +Iterator_Interfaces + child of Ada 5.5.1(2/3) +iterator_specification 5.5.2(2/3) + used 4.5.8(1/3), 5.5(3/3), P + +J + +j + in Ada.Numerics.Generic_Complex_- + +Types G.1.1(5) + + in Interfaces.Fortran B.5(10) + +known_discriminant_part 3.7(4) + used 3.2.1(3/3), 3.7(2/2), 9.1(2/3), + +9.4(2/3), P + +L + +label 5.1(7) + used 5.1(2/3), 5.1(3), P +Landau symbol O(X) A.18(3/2) +language + interface to assembly C.1(4/3) + interface to non-Ada B(1) + in Ada.Locales A.19(6/3) +Language code standard 1.2(1.1/3) +language-defined categories + [partial] 3.2(10/2) +language-defined category + of types 3.2(2/2) +language-defined check 11.5(2/3), + +11.6(1/3) + +language-defined class + [partial] 3.2(10/2) + of types 3.2(2/2) +Language-defined constants Q.5(1/3) +Language-defined exceptions Q.4(1/3) +Language-Defined Library Units A(1) +Language-defined objects Q.5(1/3) +Language-defined packages Q.1(1/3) +Language-defined subprograms Q.3(1/3) +Language-defined subtypes Q.2(1/3) +Language-defined types Q.2(1/3) +Language-defined values Q.5(1/3) +Language_Code + in Ada.Locales A.19(4/3) +Language_Unknown + in Ada.Locales A.19(5/3) + + in Ada.Iterator_Interfaces 5.5.1(4/3) +Last attribute 3.5(13), 3.6.2(5) +last element + of a hashed set A.18.8(68/2) + of a set A.18.7(6/2) + of an ordered set A.18.9(81/3) +last node + of a hashed map A.18.5(46/2) + of a map A.18.4(6/2) + of an ordered map A.18.6(58/3) +Last(N) attribute 3.6.2(6) +last_bit 13.5.1(6) + used 13.5.1(3), P +Last_Bit attribute 13.5.2(4/2) +Last_Child + in Ada.Containers.Multiway_Trees + +A.18.10(62/3) +Last_Child_Element + in Ada.Containers.Multiway_Trees + +A.18.10(63/3) + +Last_Element + in Ada.Containers.Doubly_Linked_- + +Lists A.18.3(36/2) + + in Ada.Containers.Ordered_Maps + +A.18.6(32/2) + + in Ada.Containers.Ordered_Sets + +A.18.9(44/2) + + in Ada.Containers.Vectors + +A.18.2(62/2) + +Last_Index + in Ada.Containers.Vectors + +A.18.2(60/2) + +Last_Key + in Ada.Containers.Ordered_Maps + +A.18.6(33/2) + +Last_Valid attribute 3.5.5(7.3/3) +lateness D.9(12) +Latin-1 3.5.2(2/3) +Latin_1 + child of Ada.Characters A.3.3(3) +Layout aspect 13.5(1) +Layout_Error + in Ada.IO_Exceptions A.13(4) + in Ada.Text_IO A.10.1(85) +LC_A + in Ada.Characters.Latin_1 A.3.3(13) +LC_A_Acute + in Ada.Characters.Latin_1 A.3.3(25) +LC_A_Circumflex + in Ada.Characters.Latin_1 A.3.3(25) + +Index + +13 December 2012 894 + + + + + + + + Ada Reference Manual — 2012 Edition + +LC_A_Diaeresis + in Ada.Characters.Latin_1 A.3.3(25) +LC_A_Grave + in Ada.Characters.Latin_1 A.3.3(25) +LC_A_Ring + in Ada.Characters.Latin_1 A.3.3(25) +LC_A_Tilde + in Ada.Characters.Latin_1 A.3.3(25) +LC_AE_Diphthong + in Ada.Characters.Latin_1 A.3.3(25) +LC_B + in Ada.Characters.Latin_1 A.3.3(13) +LC_C + in Ada.Characters.Latin_1 A.3.3(13) +LC_C_Cedilla + in Ada.Characters.Latin_1 A.3.3(25) +LC_D + in Ada.Characters.Latin_1 A.3.3(13) +LC_E + in Ada.Characters.Latin_1 A.3.3(13) +LC_E_Acute + in Ada.Characters.Latin_1 A.3.3(25) +LC_E_Circumflex + in Ada.Characters.Latin_1 A.3.3(25) +LC_E_Diaeresis + in Ada.Characters.Latin_1 A.3.3(25) +LC_E_Grave + in Ada.Characters.Latin_1 A.3.3(25) +LC_F + in Ada.Characters.Latin_1 A.3.3(13) +LC_G + in Ada.Characters.Latin_1 A.3.3(13) +LC_German_Sharp_S + in Ada.Characters.Latin_1 A.3.3(24) +LC_H + in Ada.Characters.Latin_1 A.3.3(13) +LC_I + in Ada.Characters.Latin_1 A.3.3(13) +LC_I_Acute + in Ada.Characters.Latin_1 A.3.3(25) +LC_I_Circumflex + in Ada.Characters.Latin_1 A.3.3(25) +LC_I_Diaeresis + in Ada.Characters.Latin_1 A.3.3(25) +LC_I_Grave + in Ada.Characters.Latin_1 A.3.3(25) +LC_Icelandic_Eth + in Ada.Characters.Latin_1 A.3.3(26) +LC_Icelandic_Thorn + in Ada.Characters.Latin_1 A.3.3(26) +LC_J + in Ada.Characters.Latin_1 A.3.3(13) +LC_K + in Ada.Characters.Latin_1 A.3.3(13) +LC_L + in Ada.Characters.Latin_1 A.3.3(13) +LC_M + in Ada.Characters.Latin_1 A.3.3(13) +LC_N + in Ada.Characters.Latin_1 A.3.3(13) + +LC_N_Tilde + in Ada.Characters.Latin_1 A.3.3(26) +LC_O + in Ada.Characters.Latin_1 A.3.3(13) +LC_O_Acute + in Ada.Characters.Latin_1 A.3.3(26) +LC_O_Circumflex + in Ada.Characters.Latin_1 A.3.3(26) +LC_O_Diaeresis + in Ada.Characters.Latin_1 A.3.3(26) +LC_O_Grave + in Ada.Characters.Latin_1 A.3.3(26) +LC_O_Oblique_Stroke + in Ada.Characters.Latin_1 A.3.3(26) +LC_O_Tilde + in Ada.Characters.Latin_1 A.3.3(26) +LC_P + in Ada.Characters.Latin_1 A.3.3(14) +LC_Q + in Ada.Characters.Latin_1 A.3.3(14) +LC_R + in Ada.Characters.Latin_1 A.3.3(14) +LC_S + in Ada.Characters.Latin_1 A.3.3(14) +LC_T + in Ada.Characters.Latin_1 A.3.3(14) +LC_U + in Ada.Characters.Latin_1 A.3.3(14) +LC_U_Acute + in Ada.Characters.Latin_1 A.3.3(26) +LC_U_Circumflex + in Ada.Characters.Latin_1 A.3.3(26) +LC_U_Diaeresis + in Ada.Characters.Latin_1 A.3.3(26) +LC_U_Grave + in Ada.Characters.Latin_1 A.3.3(26) +LC_V + in Ada.Characters.Latin_1 A.3.3(14) +LC_W + in Ada.Characters.Latin_1 A.3.3(14) +LC_X + in Ada.Characters.Latin_1 A.3.3(14) +LC_Y + in Ada.Characters.Latin_1 A.3.3(14) +LC_Y_Acute + in Ada.Characters.Latin_1 A.3.3(26) +LC_Y_Diaeresis + in Ada.Characters.Latin_1 A.3.3(26) +LC_Z + in Ada.Characters.Latin_1 A.3.3(14) +Leading_Nonseparate + in Interfaces.COBOL B.4(23) +Leading_Part attribute A.5.3(54) +Leading_Separate + in Interfaces.COBOL B.4(23) +leaf node + of a tree A.18.10(4/3) +Leap_Seconds_Count subtype of Integer + in Ada.Calendar.Arithmetic 9.6.1(11/2) +leaving 7.6.1(3/2) + +left 7.6.1(3/2) +left parenthesis 2.1(15/3) +Left_Angle_Quotation + in Ada.Characters.Latin_1 A.3.3(21/3) +Left_Curly_Bracket + in Ada.Characters.Latin_1 A.3.3(14) +Left_Parenthesis + in Ada.Characters.Latin_1 A.3.3(8) +Left_Square_Bracket + in Ada.Characters.Latin_1 A.3.3(12) +legal + construct 1.1.2(27) + partition 1.1.2(29) +legality rules 1.1.2(27) +length + of a dimension of an array 3.6(13) + of a list container A.18.3(3/2) + of a map A.18.4(5/2) + of a one-dimensional array 3.6(13) + of a set A.18.7(5/2) + of a vector container A.18.2(2/2) + in Ada.Containers.Doubly_Linked_- + +Lists A.18.3(11/2) + + in Ada.Containers.Hashed_Maps + + in Ada.Containers.Hashed_Sets + + in Ada.Containers.Ordered_Maps + + in Ada.Containers.Ordered_Sets + +A.18.5(10/2) + +A.18.8(12/2) + +A.18.6(9/2) + +A.18.9(11/2) + +A.18.2(21/2) + + in Ada.Containers.Vectors + + in Ada.Strings.Bounded A.4.4(9) + in Ada.Strings.Unbounded A.4.5(6) + in Ada.Text_IO.Editing F.3.3(11) + in Interfaces.COBOL B.4(34), B.4(39), + +B.4(44) + +Length attribute 3.6.2(9) +Length(N) attribute 3.6.2(10) +Length_Check 11.5(15) + [partial] 4.5.1(8), 4.6(37), 4.6(52) +Length_Error + in Ada.Strings A.4.1(5) +Length_Range subtype of Natural + in Ada.Strings.Bounded A.4.4(8) +less than operator 4.4(1/3), 4.5.2(1) +less than or equal operator 4.4(1/3), + +4.5.2(1) + +less-than sign 2.1(15/3) +Less_Case_Insensitive + child of Ada.Strings A.4.10(13/3) + child of Ada.Strings.Bounded + + child of Ada.Strings.Fixed + +A.4.10(18/3) + +A.4.10(16/3) + + child of Ada.Strings.Unbounded + +A.4.10(21/3) +Less_Than_Sign + in Ada.Characters.Latin_1 A.3.3(10) + +895 13 December 2012 + +Index + + Ada Reference Manual — 2012 Edition + +letter + a category of Character A.3.2(24) +letter_lowercase 2.1(9/2) + used 2.3(3/2), P +letter_modifier 2.1(9.2/2) + used 2.3(3/2), P +letter_other 2.1(9.3/2) + used 2.3(3/2), P +Letter_Set + in Ada.Strings.Maps.Constants + +A.4.6(4) + +letter_titlecase 2.1(9.1/2) + used 2.3(3/2), P +letter_uppercase 2.1(8/2) + used 2.3(3/2), P +level + accessibility 3.10.2(3/2) + library 3.10.2(22) +lexical element 2.2(1) +lexicographic order 4.5.2(26/3) +LF + in Ada.Characters.Latin_1 A.3.3(5) +library 10.1.4(9) + [partial] 10.1.1(9) + informal introduction 10(2) + See also library level, library unit, + +library_item + +library level 3.10.2(22) +Library unit 10.1(3), 10.1.1(9), N(22) + informal introduction 10(2) + See also language-defined library units +library unit pragma 10.1.5(7/3) + All_Calls_Remote E.2.3(6) + categorization pragmas E.2(2/3) + Elaborate_Body 10.2.1(24) + Preelaborate 10.2.1(4) + Pure 10.2.1(15) +library_item 10.1.1(4) + informal introduction 10(2) + used 10.1.1(3), P +library_unit_body 10.1.1(7) + used 10.1.1(4), P +library_unit_declaration 10.1.1(5) + used 10.1.1(4), P +library_unit_renaming_declaration + +10.1.1(6) + + used 10.1.1(4), P +lifetime 3.10.2(3/2) +limited interface 3.9.4(5/2) +limited type 7.5(3/3), N(23/2) + becoming nonlimited 7.3.1(5/1), + +7.5(16) + + immutably 7.5(8.1/3) +limited view 10.1.1(12.1/2) +Limited_Controlled + in Ada.Finalization 7.6(7/2) +limited_with_clause 10.1.2(4.1/2) + used 10.1.2(4/2), P +line 2.2(2/3) + in Ada.Text_IO A.10.1(38) + +line terminator A.10(7) +Line_Length + in Ada.Text_IO A.10.1(25) +link name B.1(35) +link-time error + See post-compilation error 1.1.2(29) + See post-compilation error 1.1.5(4) +Link_Name aspect B.1(1/3) +Linker_Options pragma B.1(8), L(19) +linking + See partition building 10.2(2) +List + in Ada.Containers.Doubly_Linked_- + +Lists A.18.3(6/3) +list container A.18.3(1/2) +List pragma 2.8(21), L(20) +List_Iterator_Interfaces + in Ada.Containers.Doubly_Linked_- + +Lists A.18.3(9.2/3) + +literal 4.2(1) + based 2.4.2(1) + decimal 2.4.1(1) + numeric 2.4(1) + See also aggregate 4.3(1) +little endian 13.5.3(2) +load time C.4(3) +local to 8.1(14) +local_name 13.1(3) + used 13.3(2), 13.4(2), 13.5.1(2), +13.5.1(3), C.5(3), J.15.2(2/3), +J.15.3(2/3), J.15.5(2/3), J.15.5(3/3), +J.15.5(4/3), J.15.6(2/3), J.15.8(2/3), +J.15.8(3/3), J.15.8(4/3), J.15.8(5/3), +J.15.8(6/3), J.15.8(7/3), J.15.13(2/3), +L(3.1/3), L(4.1/3), L(5.1/3), L(8.1/3), +L(9), L(13.1/3), L(14.1/3), L(14.2/3), +L(14.3/3), L(21.2/3), L(24.1/3), +L(37.2/3), L(38.1/3), L(39.1/3), P + +locale A.19(1/3) + active A.19(8/3) +Locales + child of Ada A.19(3/3) +locking policy D.3(6/2) + Ceiling_Locking D.3(7) +Locking_Policy pragma D.3(3), L(21) +Log + in Ada.Numerics.Generic_Complex_- +Elementary_Functions G.1.2(3) + in Ada.Numerics.Generic_Elementary_- + +Functions A.5.1(4) + +Logical + in Interfaces.Fortran B.5(7) +logical operator 4.5.1(2) + See also not operator 4.5.6(3) +logical_operator 4.5(2) +long + in Interfaces.C B.3(7) +Long_Binary + in Interfaces.COBOL B.4(10) + +long_double + in Interfaces.C B.3(17) +Long_Float 3.5.7(15), 3.5.7(16), + +3.5.7(17) +Long_Floating + in Interfaces.COBOL B.4(9) +Long_Integer 3.5.4(22), 3.5.4(25), + +3.5.4(28) +Look_Ahead + in Ada.Text_IO A.10.1(43) +loop cursor 5.5.2(12/3) +loop iterator 5.5.2(10/3) + container element iterator 5.5.2(12/3) +loop parameter 5.5(6), 5.5.2(7/3) +loop_parameter_specification 5.5(4) + used 4.5.8(1/3), 5.5(3/3), P +loop_statement 5.5(2) + used 5.1(5/2), P +low line 2.1(15/3) +low-level programming C(1) +Low_Line + in Ada.Characters.Latin_1 A.3.3(12) +Low_Order_First 13.5.3(2) + in Interfaces.COBOL B.4(25) + in System 13.7(15/2) +lower bound + of a range 3.5(4) +lower-case letter + a category of Character A.3.2(25) +Lower_Case_Map + in Ada.Strings.Maps.Constants + +A.4.6(5) + +Lower_Set + in Ada.Strings.Maps.Constants + +A.4.6(4) + +M + +Machine attribute A.5.3(60) +machine code insertion 13.8(1), C.1(2) +machine numbers + of a fixed point type 3.5.9(8/2) + of a floating point type 3.5.7(8) +machine scalar 13.3(8.1/3) +Machine_Code + child of System 13.8(7) +Machine_Emax attribute A.5.3(8) +Machine_Emin attribute A.5.3(7) +Machine_Mantissa attribute A.5.3(6) +Machine_Overflows attribute A.5.3(12), + +A.5.4(4) + +Machine_Radix aspect F.1(1) +Machine_Radix attribute A.5.3(2), + +A.5.4(2) + +Machine_Radix clause 13.3(7/2), F.1(1) +Machine_Rounding attribute + +A.5.3(41.1/2) + +Machine_Rounds attribute A.5.3(11), + +A.5.4(3) + +Index + +13 December 2012 896 + + + + Ada Reference Manual — 2012 Edition + +macro + See generic unit 12(1) +Macron + in Ada.Characters.Latin_1 A.3.3(21/3) +main subprogram + for a partition 10.2(7) +malloc + See allocator 4.8(1) +Map + in Ada.Containers.Hashed_Maps + +A.18.5(3/3) + + in Ada.Containers.Ordered_Maps + +A.18.6(4/3) + +map container A.18.4(1/2) +Map_Iterator_Interfaces + in Ada.Containers.Hashed_Maps + +A.18.5(6.2/3) + + in Ada.Containers.Ordered_Maps + +A.18.6(7.2/3) + +Maps + child of Ada.Strings A.4.2(3/2) +mark_non_spacing 2.1(9.4/2), 2.1(9.5/2) + used 2.3(3.1/3), P +mark_spacing_combining + used 2.3(3.1/3), P +marshalling E.4(9) +Masculine_Ordinal_Indicator + in Ada.Characters.Latin_1 A.3.3(22) +master 7.6.1(3/2) +master of a call 3.10.2(10.1/3) +match + a character to a pattern character + +A.4.2(54) + + a character to a pattern character, with +respect to a character mapping +function A.4.2(64) + + a string to a pattern string A.4.2(54) +matching components 4.5.2(16) +Max attribute 3.5(19) +Max_Alignment_For_Allocation + +attribute 13.11.1(4/3) + +Max_Asynchronous_Select_Nesting + +restriction D.7(18/1) +Max_Base_Digits 3.5.7(6) + in System 13.7(8) +Max_Binary_Modulus 3.5.4(7) + in System 13.7(7) +Max_Decimal_Digits + in Ada.Decimal F.2(5) +Max_Delta + in Ada.Decimal F.2(4) +Max_Digits 3.5.7(6) + in System 13.7(8) +Max_Digits_Binary + in Interfaces.COBOL B.4(11) +Max_Digits_Long_Binary + in Interfaces.COBOL B.4(11) +Max_Entry_Queue_Length restriction + +D.7(19.1/2) + +Max_Image_Width + in Ada.Numerics.Discrete_Random + +A.5.2(25) + + in Ada.Numerics.Float_Random + +A.5.2(13) +Max_Int 3.5.4(14) + in System 13.7(6) +Max_Length + in Ada.Strings.Bounded A.4.4(5) +Max_Mantissa + in System 13.7(9) +Max_Nonbinary_Modulus 3.5.4(7) + in System 13.7(7) +Max_Picture_Length + in Ada.Text_IO.Editing F.3.3(8) +Max_Protected_Entries restriction + +D.7(14) +Max_Scale + in Ada.Decimal F.2(3) +Max_Select_Alternatives restriction + +D.7(12) + +Max_Size_In_Storage_Elements + +attribute 13.11.1(3/3) + +Max_Storage_At_Blocking restriction + +D.7(17/1) + +Max_Task_Entries restriction D.7(13) +Max_Tasks restriction D.7(19/1) +maximum box error + for a component of the result of + +evaluating a complex function +G.2.6(3) + +maximum line length A.10(11) +maximum page length A.10(11) +maximum relative error + for a component of the result of + +evaluating a complex function +G.2.6(3) + + for the evaluation of an elementary + +function G.2.4(2) + +Members + in + +Ada.Execution_Time.Group_Budgets +D.14.2(8/2) + +Membership + in Ada.Strings A.4.1(6) +membership test 4.5.2(2/3) +membership_choice 4.4(3.2/3) + used 4.4(3.1/3), P +membership_choice_list 4.4(3.1/3) + used 4.4(3/3), P +Memory_Size + in System 13.7(13) +mentioned + in a with_clause 10.1.2(6/2) +Merge + in Ada.Containers.Doubly_Linked_- + +Lists A.18.3(50/2) + in Ada.Containers.Vectors + +A.18.2(78/2) + +message + See dispatching call 3.9.2(1/2) +method + See dispatching subprogram 3.9.2(1/2) +metrics 1.1.2(35) +Micro_Sign + in Ada.Characters.Latin_1 A.3.3(22) +Microseconds + in Ada.Real_Time D.8(14/2) +Middle_Dot + in Ada.Characters.Latin_1 A.3.3(22) +Milliseconds + in Ada.Real_Time D.8(14/2) +Min attribute 3.5(16) +Min_Delta + in Ada.Decimal F.2(4) +Min_Handler_Ceiling + in + +Ada.Execution_Time.Group_Budgets +D.14.2(7/2) + + in Ada.Execution_Time.Timers + +D.14.1(6/2) +Min_Int 3.5.4(14) + in System 13.7(6) +Min_Scale + in Ada.Decimal F.2(3) +minus 2.1(15/3) +minus operator 4.4(1/3), 4.5.3(1), + +4.5.4(1) +Minus_Sign + in Ada.Characters.Latin_1 A.3.3(8) +Minute + in Ada.Calendar.Formatting + +9.6.1(25/2) + +Minute_Number subtype of Natural + in Ada.Calendar.Formatting + +9.6.1(20/2) + +Minutes + in Ada.Real_Time D.8(14/2) +mixed-language programs B(1), C.1(4/3) +Mod attribute 3.5.4(16.1/2) +mod operator 4.4(1/3), 4.5.5(1) +mod_clause J.8(1) + used 13.5.1(2), P +mode 6.1(16) + used 6.1(15/3), 12.4(2/3), P + in Ada.Direct_IO A.8.4(9) + in Ada.Sequential_IO A.8.1(9) + in Ada.Streams.Stream_IO A.12.1(11) + in Ada.Text_IO A.10.1(12) +mode conformance 6.3.1(16/3) + required 8.5.4(4/3), 8.5.4(5/3), +12.6(7/3), 12.6(8/3), 13.3(6) + +mode of operation + nonstandard 1.1.5(11) + standard 1.1.5(11) +Mode_Error + in Ada.Direct_IO A.8.4(18) + in Ada.IO_Exceptions A.13(4) + in Ada.Sequential_IO A.8.1(15) + +897 13 December 2012 + +Index + + Ada Reference Manual — 2012 Edition + + in Ada.Streams.Stream_IO A.12.1(26) + in Ada.Text_IO A.10.1(85) +Model attribute A.5.3(68), G.2.2(7) +model interval G.2.1(4) + associated with a value G.2.1(4) +model number G.2.1(3) +model-oriented attributes + of a floating point subtype A.5.3(63) +Model_Emin attribute A.5.3(65), + +G.2.2(4) + +Model_Epsilon attribute A.5.3(66) +Model_Mantissa attribute A.5.3(64), + +G.2.2(3/2) + +Model_Small attribute A.5.3(67) +Modification_Time + in Ada.Directories A.16(27/2), + +A.16(42/2) + +modular type 3.5.4(1) +Modular_IO + in Ada.Text_IO A.10.1(57) +modular_type_definition 3.5.4(4) + used 3.5.4(2), P +module + See package 7(1) +modulus + of a modular type 3.5.4(7) + in Ada.Numerics.Generic_Complex_- +Arrays G.3.2(10/2), G.3.2(30/2) + in Ada.Numerics.Generic_Complex_- + +Types G.1.1(9) + +Modulus attribute 3.5.4(17) +Monday + in Ada.Calendar.Formatting + +9.6.1(17/2) + +Month + in Ada.Calendar 9.6(13) + in Ada.Calendar.Formatting + +9.6.1(22/2) + +Month_Number subtype of Integer + in Ada.Calendar 9.6(11/2) +More_Entries + in Ada.Directories A.16(34/2) +Move + in Ada.Containers.Doubly_Linked_- + +Lists A.18.3(18/2) + + in Ada.Containers.Hashed_Maps + +A.18.5(18/2) + + in Ada.Containers.Hashed_Sets + +A.18.8(18/2) + + in Ada.Containers.Indefinite_Holders + +A.18.18(22/3) + + in Ada.Containers.Multiway_Trees + +A.18.10(34/3) + + in Ada.Containers.Ordered_Maps + +A.18.6(17/2) + + in Ada.Containers.Ordered_Sets + +A.18.9(17/2) + + in Ada.Containers.Vectors + +A.18.2(35/2) + + in Ada.Strings.Fixed A.4.3(7) + +multi-dimensional array 3.6(12) +Multiplication_Sign + in Ada.Characters.Latin_1 A.3.3(24) +multiply 2.1(15/3) +multiply operator 4.4(1/3), 4.5.5(1) +multiplying operator 4.5.5(1) +multiplying_operator 4.5(6) + used 4.4(5), P +Multiprocessors + child of System D.16(3/3) +Multiway_Trees + child of Ada.Containers A.18.10(7/3) +mutates 7.6(17.6/3) +MW + in Ada.Characters.Latin_1 A.3.3(18) + +N + +n-dimensional array_aggregate 4.3.3(6) +NAK + in Ada.Characters.Latin_1 A.3.3(6) +name 4.1(2/3) + [partial] 3.1(1) + of (a view of) an entity 3.1(8) + of a pragma 2.8(9) + of an external file A.7(1) + used 2.8(3/3), 3.2.2(4), 4.1(4), 4.1(5), +4.1(6), 4.1.5(4/3), 4.4(7/3), 4.6(2), +4.8(2.1/3), 5.2(2), 5.5.2(2/3), 5.7(2), +5.8(2), 6.4(2), 6.4(3), 6.4(6), 8.4(3), +8.5.1(2/3), 8.5.2(2/3), 8.5.3(2/3), +8.5.4(2/3), 8.5.5(2/3), 9.5.3(2), +9.5.4(2/3), 9.8(2), 10.1.1(8), +10.1.2(4.1/2), 10.1.2(4.2/2), 10.2.1(3), +10.2.1(14), 10.2.1(20), 10.2.1(21), +10.2.1(22), 11.2(5), 11.3(2/2), +12.3(2/3), 12.3(5), 12.6(4), 12.7(2/3), +13.1(3), 13.1.1(4/3), 13.3(2), +13.11.3(3.1/3), 13.12(4.1/2), E.2.1(3), +E.2.2(3), E.2.3(3), E.2.3(5), H.3.2(3), +J.10(3/2), J.15.1(2/3), J.15.7(2/3), +J.15.7(4/3), L(2), L(6.1/3), L(10), +L(11), L(12), L(15.1/3), L(16), +L(17.1/3), L(26), L(28), L(30), L(31), +L(34), P + + in Ada.Direct_IO A.8.4(9) + in Ada.Sequential_IO A.8.1(9) + in Ada.Streams.Stream_IO A.12.1(11) + in Ada.Text_IO A.10.1(12) + in System 13.7(4) +name resolution rules 1.1.2(26/3) +Name_Case_Equivalence + in Ada.Directories A.16(20.2/3) +Name_Case_Kind + in Ada.Directories A.16(20.1/3) +Name_Error + in Ada.Direct_IO A.8.4(18) + in Ada.Directories A.16(43/2) + in Ada.IO_Exceptions A.13(4) + in Ada.Sequential_IO A.8.1(15) + + in Ada.Streams.Stream_IO A.12.1(26) + in Ada.Text_IO A.10.1(85) +named + in a use clause 8.4(7.1/2) + in a with_clause 10.1.2(6/2) +named association 6.4(7), 6.4.1(2/3), + +12.3(6) + +named component association 4.3.1(6) +named discriminant association 3.7.1(4) +named entry index 9.5.2(21) +named number 3.3(24) +named parameter association 6.4.1(2/3) +named type 3.2.1(7/2) +named_array_aggregate 4.3.3(4) + used 4.3.3(2), P +Names + child of Ada.Interrupts C.3.2(12) +Nanoseconds + in Ada.Real_Time D.8(14/2) +Native_Binary + in Interfaces.COBOL B.4(25) +Natural 3.5.4(12) +Natural subtype of Integer + in Standard A.1(13) +NBH + in Ada.Characters.Latin_1 A.3.3(17) +NBSP + in Ada.Characters.Latin_1 A.3.3(21/3) +needed + of a compilation unit by another + +10.2(2) + + remote call interface E.2.3(18) + shared passive library unit E.2.1(11) +needed component + extension_aggregate + +record_component_association_list +4.3.2(6) + + record_aggregate + +record_component_association_list +4.3.1(9) + +needs finalization 7.6(9.1/2) + language-defined type A.4.5(72.1/2), + +A.5.2(15.1/2), A.5.2(27.1/2), +A.8.1(17/2), A.8.4(20/2), +A.10.1(86/2), A.12.1(27.1/2), +A.16(102/2), A.18.2(147.3/3), +A.18.2(84/2), A.18.3(56/2), +A.18.3(86.3/3), A.18.4(4/2), +A.18.4(41.3/3), A.18.7(4/2), +A.18.7(36.2/3), A.18.7(96.2/3), +A.18.10(124/3), A.18.10(73/3), +A.18.18(27/3), A.18.18(54/3), +D.14.2(13/2), D.15(8/2) + +NEL + in Ada.Characters.Latin_1 A.3.3(17) +new + See allocator 4.8(1) +New_Char_Array + in Interfaces.C.Strings B.3.1(9) + +Index + +13 December 2012 898 + + + + New_Line + in Ada.Text_IO A.10.1(28) +New_Page + in Ada.Text_IO A.10.1(31) +New_String + in Interfaces.C.Strings B.3.1(10) +Next + in Ada.Containers.Doubly_Linked_- +Lists A.18.3(37/2), A.18.3(39/2) + + in Ada.Containers.Hashed_Maps +A.18.5(28/2), A.18.5(29/2) + in Ada.Containers.Hashed_Sets +A.18.8(41/2), A.18.8(42/2) + in Ada.Containers.Ordered_Maps +A.18.6(34/2), A.18.6(35/2) + in Ada.Containers.Ordered_Sets +A.18.9(45/2), A.18.9(46/2) + in Ada.Containers.Vectors +A.18.2(63/2), A.18.2(64/2) + + in Ada.Iterator_Interfaces 5.5.1(3/3) +Next_Sibling + in Ada.Containers.Multiway_Trees +A.18.10(64/3), A.18.10(66/3) +No_Abort_Statements restriction + +D.7(5/3) + +No_Access_Parameter_Allocators + +restriction H.4(8.3/3) + +No_Access_Subprograms restriction + +H.4(17) + +No_Allocators restriction H.4(7) +No_Anonymous_Allocators restriction + +H.4(8.1/3) +No_Break_Space + in Ada.Characters.Latin_1 A.3.3(21/3) +No_Coextensions restriction H.4(8.2/3) +No_Delay restriction H.4(21) +No_Dependence restriction 13.12.1(6/2) +No_Dispatch restriction H.4(19) +No_Dynamic_Attachment restriction + +D.7(10/3) + +No_Dynamic_Priorities restriction + +D.7(9/2) +No_Element + in Ada.Containers.Doubly_Linked_- + +Lists A.18.3(9/2) + + in Ada.Containers.Hashed_Maps + +A.18.5(6/2) + + in Ada.Containers.Hashed_Sets + +Ada Reference Manual — 2012 Edition + +No_Implementation_Aspect_Specification + +s restriction 13.12.1(1.1/3) +No_Implementation_Attributes +restriction 13.12.1(2/2) +No_Implementation_Identifiers +restriction 13.12.1(2.1/3) + +No_Implementation_Pragmas restriction + + of a tree A.18.10(2/3) +Node_Count + in Ada.Containers.Multiway_Trees + +A.18.10(17/3) + +nominal subtype 3.3(23/3), 3.3.1(8/2) + associated with a dereference 4.1(9/3) + associated with a type_conversion + +13.12.1(3/2) + +4.6(27) + +No_Implementation_Units restriction + + associated with an indexed_component + +13.12.1(3.1/3) + +No_Implicit_Heap_Allocations + +restriction D.7(8) + +No_Index + in Ada.Containers.Vectors A.18.2(7/2) +No_IO restriction H.4(20/2) +No_Local_Allocators restriction H.4(8/1) +No_Local_Protected_Objects restriction + +D.7(10.1/3) + +No_Local_Timing_Events restriction + +D.7(10.2/3) + +4.1.1(5) + + of a component 3.6(20) + of a formal parameter 6.1(23/2) + of a function result 6.1(23/2) + of a generic formal object 12.4(9/2) + of a record component 3.8(14) + of the result of a function_call + +6.4(12/2) +Non_Preemptive + child of Ada.Dispatching D.2.4(2.2/3) +Non_Preemptive_FIFO_Within_Priorities + +No_Nested_Finalization restriction + +task disp. policy D.2.4(2/2) + +D.7(4/3) + +No_Obsolescent_Features restriction + +13.12.1(4/3) + +No_Protected_Type_Allocators +restriction D.7(10.3/2) + +No_Protected_Types restriction H.4(5) +No_Recursion restriction H.4(22) +No_Reentrancy restriction H.4(23) +No_Relative_Delay restriction + +D.7(10.5/3) + +No_Requeue_Statements restriction + +nonconfirming + aspect specification 13.1(18.2/3) + representation item 13.1(18.2/3) + representation value 13.1(18.2/3) +nondispatching call + on a dispatching operation 3.9.2(1/2) +nonexistent 13.11.2(10/2), 13.11.2(16/3) +nongraphic character 3.5(27.5/2) +nonlimited interface 3.9.4(5/2) +nonlimited type 7.5(7) + becoming nonlimited 7.3.1(5/1), + +D.7(10.6/3) + +7.5(16) + +No_Return aspect 6.5.1(3.2/3) +No_Return pragma J.15.2(2/3), L(21.2/3) +No_Select_Statements restriction + +D.7(10.7/3) + +No_Specific_Termination_Handlers + +restriction D.7(10.8/3) + +No_Specification_of_Aspect restriction + +13.12.1(6.1/3) + +No_Standard_Allocators_After_Elaborati + +on restriction D.7(19.2/3) + +No_Tag + in Ada.Tags 3.9(6.1/2) +No_Task_Allocators restriction D.7(7) +No_Task_Hierarchy restriction D.7(3/3) +No_Task_Termination restriction + +nonlimited_with_clause 10.1.2(4.2/2) + used 10.1.2(4/2), P +nonnormative + See informative 1.1.2(18) +nonreturning 6.5.1(3.2/3) +nonstandard integer type 3.5.4(26) +nonstandard mode 1.1.5(11) +nonstandard real type 3.5.6(8) +normal completion 7.6.1(2/2) +normal library unit E.2(4/3) +normal state of an object 11.6(6/3), + +13.9.1(4) + + [partial] 9.8(21), A.13(17) +Normalize_Scalars pragma H.1(3), L(22) +normalized exponent A.5.3(14) +normalized number A.5.3(10) +normative 1.1.2(14) +not equal operator 4.4(1/3), 4.5.2(1) +not in (membership test) 4.4(1/3), + +A.18.8(6/2) + +D.7(15.1/2) + + in Ada.Containers.Multiway_Trees + +No_Terminate_Alternatives restriction + +A.18.10(11/3) + +D.7(6) + + in Ada.Containers.Ordered_Maps + +No_Unchecked_Access restriction + +A.18.6(7/2) + +H.4(18) + +4.5.2(2/3) + + in Ada.Containers.Ordered_Sets + +No_Use_Of_Attribute restriction + +A.18.9(7/2) + +13.12.1(6.2/3) + + in Ada.Containers.Vectors + +No_Use_Of_Pragma restriction + +A.18.2(11/2) + +13.12.1(6.3/3) + +No_Exceptions restriction H.4(12) +No_Fixed_Point restriction H.4(15) +No_Floating_Point restriction H.4(14) + +node + of a list A.18.3(2/2) + of a map A.18.4(5/2) + +not operator 4.4(1/3), 4.5.6(3) +Not_A_Specific_CPU + in System.Multiprocessors D.16(4/3) +Not_Sign + in Ada.Characters.Latin_1 A.3.3(21/3) +notes 1.1.2(38) + +899 13 December 2012 + +Index + + Ada Reference Manual — 2012 Edition + +notwithstanding 7.6(17.5/3), 10.1.6(6/2), +B.1(22/3), B.1(38/3), C.3.1(19/3), +E.2.1(8), E.2.1(11), E.2.3(18), +H.6(7/2), J.3(6) + [partial] J.15.5(8/3) +NUL + in Ada.Characters.Latin_1 A.3.3(5) + in Interfaces.C B.3(20/1) +null access value 4.2(9) +null array 3.6.1(7) +null constraint 3.2(7/2) +null extension 3.9.1(4.1/2) +null pointer + See null access value 4.2(9) +null procedure 6.7(3/3) +null range 3.5(4) +null record 3.8(15) +null slice 4.1.2(7) +null string literal 2.6(6) +null value + of an access type 3.10(13/2) +Null_Address + in System 13.7(12) +Null_Bounded_String + in Ada.Strings.Bounded A.4.4(7) +null_exclusion 3.10(5.1/2) + used 3.2.2(3/2), 3.7(5/2), 3.10(2/2), +3.10(6/2), 6.1(13/2), 6.1(15/3), +8.5.1(2/3), 12.4(2/3), P + +Null_Id + in Ada.Exceptions 11.4.1(2/2) +Null_Occurrence + in Ada.Exceptions 11.4.1(3/2) +null_procedure_declaration 6.7(2/3) + used 3.1(3/3), P +Null_Ptr + in Interfaces.C.Strings B.3.1(7) +Null_Set + in Ada.Strings.Maps A.4.2(5) + in Ada.Strings.Wide_Maps A.4.7(5) + in Ada.Strings.Wide_Wide_Maps + +A.4.8(5/2) + +null_statement 5.1(6) + used 5.1(4/2), P +Null_Task_Id + in Ada.Task_Identification C.7.1(2/2) +Null_Unbounded_String + in Ada.Strings.Unbounded A.4.5(5) +number sign 2.1(15/3) +Number_Base subtype of Integer + in Ada.Text_IO A.10.1(6) +number_decimal 2.1(10/2) + used 2.3(3.1/3), P +number_declaration 3.3.2(2) + used 3.1(3/3), P +number_letter 2.1(10.1/2) + used 2.3(3/2), P +Number_Of_CPUs + in System.Multiprocessors D.16(5/3) + +Number_Sign + in Ada.Characters.Latin_1 A.3.3(8) +numeral 2.4.1(3) + used 2.4.1(2), 2.4.1(4), 2.4.2(3), P +Numeric + in Interfaces.COBOL B.4(20/3) +numeric type 3.5(1) +numeric_literal 2.4(2) + used 4.4(7/3), P +numerics G(1) + child of Ada A.5(3/2) + +O + +O(f(N)) A.18(3/2) +object 3.3(2), N(24) + [partial] 3.2(1) +object-oriented programming (OOP) + See dispatching operations of tagged + +types 3.9.2(1/2) + + See tagged types and type extensions + +3.9(1) + +object_declaration 3.3.1(2/3) + used 3.1(3/3), P +object_renaming_declaration 8.5.1(2/3) + used 8.5(2), P +obsolescent feature J(1/2) +occur immediately within 8.1(13) +occurrence + of an interrupt C.3(2) +octal + literal 2.4.2(1) +octal literal 2.4.2(1) +Old attribute 6.1.1(26/3) +one's complement + modular types 3.5.4(27) +one-dimensional array 3.6(12) +only as a completion + entry_body 9.5.2(16) +OOP (object-oriented programming) + See dispatching operations of tagged + +types 3.9.2(1/2) + + See tagged types and type extensions + +3.9(1) +opaque type + See private types and private + +extensions 7.3(1) + +Open + in Ada.Direct_IO A.8.4(7) + in Ada.Sequential_IO A.8.1(7) + in Ada.Streams.Stream_IO A.12.1(9) + in Ada.Text_IO A.10.1(10) +open alternative 9.7.1(14) +open entry 9.5.3(5) + of a protected object 9.5.3(7/3) + of a task 9.5.3(6/3) +operand + of a qualified_expression 4.7(3) + of a type_conversion 4.6(3) +operand interval G.2.1(6) + +operand type + of a type_conversion 4.6(3) +operates on a type 3.2.3(1/2) +operational aspect 13.1(8.1/3) + specifiable attributes 13.3(5/3) +operational item 13.1(1.1/1) +operator 6.6(1) + & 4.4(1/3), 4.5.3(3) + * 4.4(1/3), 4.5.5(1) + ** 4.4(1/3), 4.5.6(7) + + 4.4(1/3), 4.5.3(1), 4.5.4(1) + - 4.4(1/3), 4.5.3(1), 4.5.4(1) + / 4.4(1/3), 4.5.5(1) + /= 4.4(1/3), 4.5.2(1) + < 4.4(1/3), 4.5.2(1) + <= 4.4(1/3), 4.5.2(1) + = 4.4(1/3), 4.5.2(1) + > 4.4(1/3), 4.5.2(1) + >= 4.4(1/3), 4.5.2(1) + abs 4.4(1/3), 4.5.6(1) + ampersand 4.4(1/3), 4.5.3(3) + and 4.4(1/3), 4.5.1(2) + binary 4.5(9) + binary adding 4.5.3(1) + concatenation 4.4(1/3), 4.5.3(3) + divide 4.4(1/3), 4.5.5(1) + equal 4.4(1/3), 4.5.2(1) + equality 4.5.2(1) + exponentiation 4.4(1/3), 4.5.6(7) + greater than 4.4(1/3), 4.5.2(1) + greater than or equal 4.4(1/3), 4.5.2(1) + highest precedence 4.5.6(1) + less than 4.4(1/3), 4.5.2(1) + less than or equal 4.4(1/3), 4.5.2(1) + logical 4.5.1(2) + minus 4.4(1/3), 4.5.3(1), 4.5.4(1) + mod 4.4(1/3), 4.5.5(1) + multiply 4.4(1/3), 4.5.5(1) + multiplying 4.5.5(1) + not 4.4(1/3), 4.5.6(3) + not equal 4.4(1/3), 4.5.2(1) + or 4.4(1/3), 4.5.1(2) + ordering 4.5.2(1) + plus 4.4(1/3), 4.5.3(1), 4.5.4(1) + predefined 4.5(9) + relational 4.5.2(1) + rem 4.4(1/3), 4.5.5(1) + times 4.4(1/3), 4.5.5(1) + unary 4.5(9) + unary adding 4.5.4(1) + user-defined 6.6(1) + xor 4.4(1/3), 4.5.1(2) +operator precedence 4.5(1) +operator_symbol 6.1(9) + used 4.1(3), 4.1.3(3), 6.1(5), 6.1(11), P +optimization 11.5(29), 11.6(1/3) +Optimize pragma 2.8(23), L(23) +or else (short-circuit control form) + +4.4(1/3), 4.5.1(1) + +or operator 4.4(1/3), 4.5.1(2) + +Index + +13 December 2012 900 + + + + Ada Reference Manual — 2012 Edition + +Ordered_Maps + child of Ada.Containers A.18.6(2/3) +Ordered_Sets + child of Ada.Containers A.18.9(2/3) +ordering operator 4.5.2(1) +ordinary file A.16(45/2) +ordinary fixed point type 3.5.9(1), + +3.5.9(8/2) + +package instance 12.3(13) +package_body 7.2(2/3) + used 3.11(6), 10.1.1(7), P +package_body_stub 10.1.3(4) + used 10.1.3(2), P +package_declaration 7.1(2) + used 3.1(3/3), 10.1.1(5), P +package_renaming_declaration + +ordinary_fixed_point_definition 3.5.9(3) + used 3.5.9(2), P +OSC + in Ada.Characters.Latin_1 A.3.3(19) +other_control 2.1(13.1/2) +other_format 2.1(10.3/2) +other_private_use 2.1(13.2/2) +other_surrogate 2.1(13.3/2) +output A.6(1/2) +Output aspect 13.13.2(38/3) +Output attribute 13.13.2(19), 13.13.2(29) +Output clause 13.3(7/2), 13.13.2(38/3) +overall interpretation + of a complete context 8.6(10) +Overflow_Check 11.5(16) + [partial] 3.5.4(20), 4.4(11), + +4.5.7(21/3), 5.4(13), G.2.1(11), +G.2.2(7), G.2.3(25), G.2.4(2), G.2.6(3) + +Overlap + in Ada.Containers.Hashed_Sets + +A.18.8(38/2) + + in Ada.Containers.Ordered_Sets + +A.18.9(39/2) + +Overlaps_Storage attribute 13.3(73.6/3) +overload resolution 8.6(1/3) +overloadable 8.3(7) +overloaded 8.3(6) + enumeration literal 3.5.1(9) +overloading rules 1.1.2(26/3), 8.6(2) +overridable 8.3(9/1) +override 8.3(9/1), 12.3(17) + a primitive subprogram 3.2.3(7/2) + when implemented by 9.1(9.2/3), + +9.4(11.1/3) + +overriding operation N(24.1/2) +overriding_indicator 8.3.1(2/2) + used 3.9.3(1.1/3), 6.1(2/3), 6.3(2/3), + +6.7(2/3), 6.8(2/3), 8.5.4(2/3), +9.5.2(2/3), 10.1.3(3/3), 12.3(2/3), P + +Overwrite + in Ada.Strings.Bounded A.4.4(62), + +A.4.4(63) + + in Ada.Strings.Fixed A.4.3(27), + +A.4.3(28) + + in Ada.Strings.Unbounded A.4.5(57), + +A.4.5(58) + +P + +8.5.3(2/3) + + used 8.5(2), 10.1.1(6), P +package_specification 7.1(3/3) + used 7.1(2), 12.1(4), P +packed 13.2(5.1/3) +Packed_Decimal + in Interfaces.COBOL B.4(12/3) +Packed_Format + in Interfaces.COBOL B.4(26) +Packed_Signed + in Interfaces.COBOL B.4(27) +Packed_Unsigned + in Interfaces.COBOL B.4(27) +padding bits 13.1(7/2) +Page + in Ada.Text_IO A.10.1(39) +Page pragma 2.8(22), L(25) +page terminator A.10(7) +Page_Length + in Ada.Text_IO A.10.1(26) +Paragraph_Sign + in Ada.Characters.Latin_1 A.3.3(22) +parallel processing + See task 9(1/3) +parameter + explicitly aliased 6.1(23.1/3) + See formal parameter 6.1(17) + See generic formal parameter 12(1) + See also discriminant 3.7(1/2) + See also loop parameter 5.5(6) +parameter assigning back 6.4.1(17) +parameter copy back 6.4.1(17) +parameter mode 6.1(18/3) +parameter passing 6.4.1(1) +parameter_and_result_profile 6.1(13/2) + used 3.10(5), 3.10(6/2), 6.1(4.2/2), P +parameter_association 6.4(5) + used 6.4(4), P +parameter_profile 6.1(12) + used 3.10(5), 3.10(6/2), 6.1(4.1/2), +9.5.2(2/3), 9.5.2(3), 9.5.2(6), P +parameter_specification 6.1(15/3) + used 6.1(14), P +Parameterless_Handler + in Ada.Interrupts C.3.2(2/3) +Params_Stream_Type + in System.RPC E.5(6) +parent N(25.1/2) + in Ada.Containers.Multiway_Trees + +Pack aspect 13.2(5.1/3) +Pack pragma J.15.3(2/3), L(24.1/3) +Package 7(1), N(25) + +A.18.10(59/3) + +parent body + of a subunit 10.1.3(8/2) + +parent declaration + of a library unit 10.1.1(10) + of a library_item 10.1.1(10) +parent subtype 3.4(3/2) +parent type 3.4(3/2) +parent unit + of a library unit 10.1.1(10) +Parent_Tag + in Ada.Tags 3.9(7.2/2) +parent_unit_name 10.1.1(8) + used 6.1(5), 6.1(7), 7.1(3/3), 7.2(2/3), + +10.1.3(7), P + +part + of a type 3.2(6/2) + of an object or value 3.2(6/2) +partial view + of a type 7.3(4) +partition 10.2(2), N(26) +partition building 10.2(2) +partition communication subsystem + +(PCS) E.5(1/2) + +Partition_Check + [partial] E.4(19) +Partition_Elaboration_Policy pragma + +H.6(3/2), L(25.1/2) + +Partition_Id + in System.RPC E.5(4) +Partition_Id attribute E.1(9) +pass by copy 6.2(2) +pass by reference 6.2(2) +passive partition E.1(2) +Pattern_Error + in Ada.Strings A.4.1(5) +PCS (partition communication +subsystem) E.5(1/2) + +Peak_Use + in + +Ada.Containers.Bounded_Priority_Qu +eues A.18.31(7/3) + + in + +Ada.Containers.Bounded_Synchronize +d_Queues A.18.29(6/3) + + in + +Ada.Containers.Synchronized_Queue_ +Interfaces A.18.27(7/3) + + in + +Ada.Containers.Unbounded_Priority_ +Queues A.18.30(7/3) + + in + +Ada.Containers.Unbounded_Synchron +ized_Queues A.18.28(6/3) +pending interrupt occurrence C.3(2) +per-object constraint 3.8(18/2) +per-object expression 3.8(18/2) +percent sign 2.1(15/3) +Percent_Sign + in Ada.Characters.Latin_1 A.3.3(8) +perfect result set G.2.3(5) + +901 13 December 2012 + +Index + + + + Ada Reference Manual — 2012 Edition + +periodic task + example 9.6(39) + See delay_until_statement 9.6(39) +Pi + in Ada.Numerics A.5(3/2) +Pic_String + in Ada.Text_IO.Editing F.3.3(7) +Picture + in Ada.Text_IO.Editing F.3.3(4) +picture String + for edited output F.3.1(1/3) +Picture_Error + in Ada.Text_IO.Editing F.3.3(9) +Pilcrow_Sign + in Ada.Characters.Latin_1 A.3.3(22) +plain_char + in Interfaces.C B.3(11) +plane + character 2.1(1/3) +PLD + in Ada.Characters.Latin_1 A.3.3(17) +PLU + in Ada.Characters.Latin_1 A.3.3(17) +plus operator 4.4(1/3), 4.5.3(1), 4.5.4(1) +plus sign 2.1(15/3) +Plus_Minus_Sign + in Ada.Characters.Latin_1 A.3.3(22) +Plus_Sign + in Ada.Characters.Latin_1 A.3.3(8) +PM + in Ada.Characters.Latin_1 A.3.3(19) +point 2.1(15/3) +Pointer + in Interfaces.C.Pointers B.3.2(5) + See access value 3.10(1) + See type System.Address 13.7(34/2) +pointer type + See access type 3.10(1) +Pointer_Error + in Interfaces.C.Pointers B.3.2(8) +Pointers + child of Interfaces.C B.3.2(4) +polymorphism 3.9(1), 3.9.2(1/2) +pool + default 13.11.3(4.1/3) + subpool 13.11.4(18/3) +pool element 3.10(7/1), 13.11(11) +pool type 13.11(11) +pool-specific access type 3.10(7/1), + +3.10(8) + +Pool_of_Subpool + in System.Storage_Pools.Subpools + +13.11.4(9/3) +Pos attribute 3.5.5(2) +position 13.5.1(4) + used 13.5.1(3), P +Position attribute 13.5.2(2/2) +position number 3.5(1) + of an enumeration value 3.5.1(7) + of an integer value 3.5.4(15) + +positional association 6.4(7), 6.4.1(2/3), + +12.3(6) + +positional component association + +4.3.1(6) + +positional discriminant association + +3.7.1(4) + +positional parameter association + +6.4.1(2/3) + +positional_array_aggregate 4.3.3(3/2) + used 4.3.3(2), P +Positive 3.5.4(12) +Positive subtype of Integer + in Standard A.1(13) +Positive_Count subtype of Count + in Ada.Direct_IO A.8.4(4) + in Ada.Streams.Stream_IO A.12.1(7) + in Ada.Text_IO A.10.1(5) +possible interpretation 8.6(14) + for direct_names 8.3(24) + for selector_names 8.3(24) +Post aspect 6.1.1(4/3) +Post'Class aspect 6.1.1(5/3) +post-compilation error 1.1.2(29) +post-compilation rules 1.1.2(29) +postcondition N(26.1/3) +postcondition check 6.1.1(35/3) +postcondition expression + class-wide 6.1.1(5/3) + specific 6.1.1(4/3) +potentially blocking operation 9.5.1(8) + Abort_Task C.7.1(16) + delay_statement 9.6(34), D.9(5) + remote subprogram call E.4(17) + RPC operations E.5(23) + Suspend_Until_True D.10(10) +potentially unevaluated expression + +6.1.1(20/3) + +potentially use-visible 8.4(8/3) + [partial] 12.6(9.2/3) +Pound_Sign + in Ada.Characters.Latin_1 A.3.3(21/3) +Pragma 2.8(1), 2.8(2), L(1), N(27) +pragma argument 2.8(9) +pragma name 2.8(9) +pragma, categorization E.2(2/3) + Remote_Call_Interface E.2.3(2) + Remote_Types E.2.2(2) + Shared_Passive E.2.1(2) +pragma, configuration 10.1.5(8) + Assertion_Policy 11.4.2(7/3) + Detect_Blocking H.5(4/2) + Discard_Names C.5(4) + Locking_Policy D.3(5) + Normalize_Scalars H.1(4) + Partition_Elaboration_Policy H.6(5/2) + Priority_Specific_Dispatching + +D.2.2(5/2) + + Profile 13.12(14/3) + Queuing_Policy D.4(5) + Restrictions 13.12(8/3) + + Reviewable H.3.1(4) + Suppress 11.5(5/2) + Task_Dispatching_Policy D.2.2(5/2) + Unsuppress 11.5(5/2) +pragma, identifier specific to 2.8(10/3) +pragma, interfacing + Convention J.15.5(1/3) + Export J.15.5(1/3) + Import J.15.5(1/3) +pragma, library unit 10.1.5(7/3) + All_Calls_Remote E.2.3(6) + categorization pragmas E.2(2/3) + Elaborate_Body 10.2.1(24) + Preelaborate 10.2.1(4) + Pure 10.2.1(15) +pragma, program unit 10.1.5(2) + Inline J.15.1(1/3) + library unit pragmas 10.1.5(7/3) +pragma, representation 13.1(1/1) + Asynchronous J.15.13(1/3) + Atomic J.15.8(9/3) + Atomic_Components J.15.8(9/3) + Convention J.15.5(1/3) + Discard_Names C.5(6) + Export J.15.5(1/3) + Import J.15.5(1/3) + Independent J.15.8(9/3) + Independent_Components J.15.8(9/3) + No_Return J.15.2(1/3) + Pack J.15.3(1/3) + Unchecked_Union J.15.6(1/3) + Volatile J.15.8(9/3) + Volatile_Components J.15.8(9/3) +pragma_argument_association 2.8(3/3) + used 2.8(2), 13.12(11/3), L(27.3/3), P +pragmas + All_Calls_Remote E.2.3(5), L(2) + Assert 11.4.2(3/2), L(2.1/2) + Assertion_Policy 11.4.2(6.1/3), +11.4.2(6/2), L(2.2/2), L(2.3/3) + Asynchronous J.15.13(2/3), L(3.1/3) + Atomic J.15.8(2/3), L(4.1/3) + Atomic_Components J.15.8(5/3), + +L(5.1/3) + + Attach_Handler J.15.7(4/3), L(6.1/3) + Convention J.15.5(4/3), L(8.1/3) + CPU J.15.9(2/3), L(8.2/3) + Default_Storage_Pool 13.11.3(3/3), + +L(8.3/3) + + Detect_Blocking H.5(3/2), L(8.4/2) + Discard_Names C.5(3), L(9) + Dispatching_Domain J.15.10(2/3), + +L(9.1/3) + + Elaborate 10.2.1(20), L(10) + Elaborate_All 10.2.1(21), L(11) + Elaborate_Body 10.2.1(22), L(12) + Export J.15.5(3/3), L(13.1/3) + Import J.15.5(2/3), L(14.1/3) + Independent J.15.8(4/3), L(14.2/3) + +Index + +13 December 2012 902 + + Independent_Components J.15.8(7/3), + +L(14.3/3) + + Inline J.15.1(2/3), L(15.1/3) + Inspection_Point H.3.2(3), L(16) + Interrupt_Handler J.15.7(2/3), + +L(17.1/3) + + Interrupt_Priority J.15.11(4/3), + +L(18.1/3) + + Linker_Options B.1(8), L(19) + List 2.8(21), L(20) + Locking_Policy D.3(3), L(21) + No_Return J.15.2(2/3), L(21.2/3) + Normalize_Scalars H.1(3), L(22) + Optimize 2.8(23), L(23) + Pack J.15.3(2/3), L(24.1/3) + Page 2.8(22), L(25) + Partition_Elaboration_Policy H.6(3/2), + +L(25.1/2) + + Preelaborable_Initialization +10.2.1(4.2/2), L(25.2/2) + Preelaborate 10.2.1(3), L(26) + Priority J.15.11(2/3), L(27.1/3) + Priority_Specific_Dispatching + +D.2.2(3.2/2), L(27.2/2) + + Profile 13.12(11/3), L(27.3/3) + Pure 10.2.1(14), L(28) + Queuing_Policy D.4(3), L(29) + Relative_Deadline J.15.12(2/3), + +L(29.2/3) + + Remote_Call_Interface E.2.3(3), L(30) + Remote_Types E.2.2(3), L(31) + Restrictions 13.12(3), L(32) + Reviewable H.3.1(3), L(33) + Shared_Passive E.2.1(3), L(34) + Storage_Size J.15.4(2/3), L(35.1/3) + Suppress 11.5(4/2), J.10(3/2), L(36) + Task_Dispatching_Policy D.2.2(3), + +L(37) + + Unchecked_Union J.15.6(2/3), + +L(37.2/3) + + Unsuppress 11.5(4.1/2), L(37.3/2) + Volatile J.15.8(3/3), L(38.1/3) + Volatile_Components J.15.8(6/3), + +L(39.1/3) + +Pre aspect 6.1.1(2/3) +Pre'Class aspect 6.1.1(3/3) +precedence of operators 4.5(1) +precondition N(27.1/3) +precondition check + class-wide 6.1.1(33/3) + specific 6.1.1(32/3) +precondition expression + class-wide 6.1.1(3/3) + specific 6.1.1(2/3) +Pred attribute 3.5(25) +predecessor element + of an ordered set A.18.9(81/3) +predecessor node + of an ordered map A.18.6(58/3) +predefined environment A(1) + +903 13 December 2012 + +Ada Reference Manual — 2012 Edition + +predefined exception 11.1(4) +predefined library unit + See language-defined library units +predefined operation + of a type 3.2.3(1/2) +predefined operations + of a discrete type 3.5.5(10/3) + of a fixed point type 3.5.10(17) + of a floating point type 3.5.8(3) + of a record type 3.8(24) + of an access type 3.10.2(34/2) + of an array type 3.6.2(15) +predefined operator 4.5(9) + [partial] 3.2.1(9) +predefined type 3.2.1(10) + See language-defined types +predicate 4.5.8(3/3), N(27.2/3) + of a subtype 3.2.4(6/3) + used 4.5.8(1/3), P +predicate aspect 3.2.4(1/3) +predicate check + allocator 3.2.4(31/3) + enabled 3.2.4(7/3) + in out parameters 3.2.4(31/3) + object_declaration 3.2.4(31/3) + subtype conversion 4.6(51/3) +predicate evaluated + membership 4.5.2(29/3) + Valid attribute 13.9.2(3/3), K.2(263/3) +predicate specification 3.2.4(1/3) +predicate-static 3.2.4(15/3) +preelaborable + of an elaborable construct 10.2.1(5) +preelaborable initialization + +10.2.1(11.1/2) + +Preelaborable_Initialization pragma + +10.2.1(4.2/2), L(25.2/2) +Preelaborate aspect 10.2.1(11/3) +Preelaborate pragma 10.2.1(3), L(26) +preelaborated 10.2.1(11/3) + [partial] 10.2.1(11/3), E.2.1(9) +preempt + a running task D.2.3(9/2) +preference + for root numeric operators and ranges + +8.6(29) + + for universal access equality operators + +8.6(29.1/3) +preference control + See requeue 9.5.4(1) +prefix 4.1(4) + of a prefixed view 4.1.3(9.2/3) + used 4.1.1(2), 4.1.2(2), 4.1.3(2), + +4.1.4(2), 4.1.4(4), 4.1.6(10/3), 6.4(2), +6.4(3), P + +prefixed view 4.1.3(9.2/3) +prefixed view profile 6.3.1(24.1/2) + +Prepend + in Ada.Containers.Doubly_Linked_- + +Lists A.18.3(22/2) + in Ada.Containers.Vectors +A.18.2(44/2), A.18.2(45/2) + +Prepend_Child + in Ada.Containers.Multiway_Trees + +A.18.10(51/3) + +prescribed result + for the evaluation of a complex + +arithmetic operation G.1.1(42) + + for the evaluation of a complex + +elementary function G.1.2(35) + for the evaluation of an elementary + +function A.5.1(37) + +Previous + in Ada.Containers.Doubly_Linked_- +Lists A.18.3(38/2), A.18.3(40/2) + in Ada.Containers.Ordered_Maps +A.18.6(36/2), A.18.6(37/2) + in Ada.Containers.Ordered_Sets +A.18.9(47/2), A.18.9(48/2) + in Ada.Containers.Vectors +A.18.2(65/2), A.18.2(66/2) + + in Ada.Iterator_Interfaces 5.5.1(4/3) +Previous_Sibling + in Ada.Containers.Multiway_Trees +A.18.10(65/3), A.18.10(67/3) + +primary 4.4(7/3) + used 4.4(6), P +primitive function A.5.3(17) +primitive operation + [partial] 3.2(1) +primitive operations N(28) + of a type 3.2.3(1/2) +primitive operator + of a type 3.2.3(8) +primitive subprograms + of a type 3.2.3(2) +priority D.1(15) + of a protected object D.3(6/2) +Priority aspect D.1(6.2/3) +Priority attribute D.5.2(3/2) +priority inheritance D.1(15) +priority inversion D.2.3(11/2) +priority of an entry call D.4(9) +Priority pragma J.15.11(2/3), L(27.1/3) +Priority subtype of Any_Priority + in System 13.7(16) +Priority_Queuing queuing policy D.4(8) +Priority_Specific_Dispatching pragma + +D.2.2(3.2/2), L(27.2/2) + +private declaration of a library unit + +10.1.1(12) +private descendant + of a library unit 10.1.1(12) +private extension 3.2(4.1/2), 3.9(2.1/2), + +3.9.1(1/2), N(29/2) + + [partial] 7.3(14), 12.5.1(5/3) +private library unit 10.1.1(12) + +Index + + Ada Reference Manual — 2012 Edition + +private operations 7.3.1(1) +private part 8.2(5) + of a package 7.1(6/2) + of a protected unit 9.4(11/2) + of a task unit 9.1(9) +private type 3.2(4.1/2), N(30/2) + [partial] 7.3(14) +private types and private extensions + +7.3(1) + +private_extension_declaration 7.3(3/3) + used 3.2.1(2), P +private_type_declaration 7.3(2/3) + used 3.2.1(2), P +procedure 6(1), N(30.1/2) + null 6.7(3/3) +procedure instance 12.3(13) +procedure_call_statement 6.4(2) + used 5.1(4/2), 9.7.2(3.1/2), P +procedure_or_entry_call 9.7.2(3.1/2) + used 9.7.2(3/2), 9.7.4(4/2), P +procedure_specification 6.1(4.1/2) + used 6.1(4/2), 6.7(2/3), P +processing node E(2) +profile 6.1(22) + associated with a dereference 4.1(10) + fully conformant 6.3.1(18/3) + mode conformant 6.3.1(16/3) + No_Implementation_Extensions + +13.12.1(10/3) + + subtype conformant 6.3.1(17/3) + type conformant 6.3.1(15/2) +Profile pragma 13.12(11/3), L(27.3/3) +profile resolution rule + name with a given expected profile + +8.6(26) + +progenitor N(30.2/2) +progenitor subtype 3.9.4(9/2) +progenitor type 3.9.4(9/2) +program 10.2(1), N(31) +program execution 10.2(1) +program library + See library 10(2) + See library 10.1.4(9) +Program unit 10.1(1), N(32) +program unit pragma 10.1.5(2) + Inline J.15.1(1/3) + library unit pragmas 10.1.5(7/3) + +Program_Error + raised by failure of run-time check + +1.1.3(20), 1.1.5(8), 1.1.5(12), 3.5.5(8), +3.10.2(29), 3.11(14), 4.6(57/3), +4.8(10.1/3), 4.8(10.2/2), 4.8(10.3/2), +4.8(10.4/3), 6.2(12/3), 6.4(11/2), +6.5(8/3), 6.5(21/3), 6.5.1(9/2), +7.6.1(15), 7.6.1(16/2), 7.6.1(17), +7.6.1(17.2/1), 7.6.1(18/2), 8.5.4(8.1/1), +9.4(20), 9.5.1(17), 9.5.3(7/3), +9.7.1(21), 9.8(20/3), 10.2(26), 11.1(4), +11.5(19), 12.5.1(23.3/2), 13.7.1(16), +13.9.1(9), 13.11.2(13), 13.11.2(14), +13.11.4(27/3), 13.11.4(30/3), +A.5.2(40.1/1), A.7(14/3), B.3.3(22/2), +C.3.1(10/3), C.3.1(11/3), C.3.2(17/3), +C.3.2(20), C.3.2(21/3), C.3.2(22/2), +C.7.1(15), C.7.1(17/3), C.7.2(13), +D.3(13), D.3(13.2/2), D.3(13.4/2), +D.5.1(9), D.5.2(6/3), D.7(7.1/3), +D.7(10.4/3), D.7(19.1/2), D.10(10), +D.11(8), E.1(10/2), E.3(6), E.4(18/1), +J.7.1(7) + +protected_operation_declaration 9.4(5/1) + used 9.4(4), 9.4(6), P +protected_operation_item 9.4(8/1) + used 9.4(7/3), P +protected_type_declaration 9.4(2/3) + used 3.2.1(3/3), P +ptrdiff_t + in Interfaces.C B.3(12) +PU1 + in Ada.Characters.Latin_1 A.3.3(18) +PU2 + in Ada.Characters.Latin_1 A.3.3(18) +public declaration of a library unit + +10.1.1(12) +public descendant + of a library unit 10.1.1(12) +public library unit 10.1.1(12) +punctuation_connector 2.1(10.2/2) + used 2.3(3.1/3), P +pure 10.2.1(15.1/3) +Pure aspect 10.2.1(17/3) +Pure pragma 10.2.1(14), L(28) +Put + in Ada.Text_IO A.10.1(42), + + in Standard A.1(46) +prohibited + tampering with a holder A.18.18(35/3) + tampering with a list A.18.3(69.1/3) + tampering with a map A.18.4(15.1/3) + tampering with a set A.18.7(14.1/3) + tampering with a tree A.18.10(90/3) + tampering with a vector A.18.2(97.1/3) +propagate 11.4(1) + an exception occurrence by an + +A.10.1(48), A.10.1(55), A.10.1(60), +A.10.1(66), A.10.1(67), A.10.1(71), +A.10.1(72), A.10.1(76), A.10.1(77), +A.10.1(82), A.10.1(83) + in Ada.Text_IO.Bounded_IO +A.10.11(4/2), A.10.11(5/2) + + in Ada.Text_IO.Complex_IO G.1.3(7), + +G.1.3(8) + + in Ada.Text_IO.Editing F.3.3(14), + +execution, to a dynamically enclosing +execution 11.4(6) +proper_body 3.11(6) + used 3.11(5), 10.1.3(7), P +protected action 9.5.1(4) + complete 9.5.1(6) + start 9.5.1(5) +protected calling convention 6.3.1(12) +protected declaration 9.4(1) +protected entry 9.4(1) +protected function 9.5.1(1) +protected interface 3.9.4(5/2) +protected object 9(3), 9.4(1) +protected operation 9.4(1) +protected procedure 9.5.1(1) +protected subprogram 9.4(1), 9.5.1(1) +protected tagged type 3.9.4(6/2) +protected type N(33/2) +protected unit 9.4(1) +protected_body 9.4(7/3) + used 3.11(6), P +protected_body_stub 10.1.3(6) + used 10.1.3(2), P +protected_definition 9.4(4) + used 9.4(2/3), 9.4(3/3), P +protected_element_declaration 9.4(6) + used 9.4(4), P + +F.3.3(15), F.3.3(16) + + in Ada.Text_IO.Unbounded_IO +A.10.12(4/2), A.10.12(5/2) + +Put_Line + in Ada.Text_IO A.10.1(50) + in Ada.Text_IO.Bounded_IO +A.10.11(6/2), A.10.11(7/2) + in Ada.Text_IO.Unbounded_IO +A.10.12(6/2), A.10.12(7/2) + +Q + +qualified_expression 4.7(2) + used 4.1(2/3), 4.8(2/3), 13.8(2), P +quantified expressions 4.5.8(5/3) +quantified_expression 4.5.8(1/3) + used 4.4(7/3), P +quantifier 4.5.8(2/3) + used 4.5.8(1/3), P +Query_Element + in Ada.Containers.Doubly_Linked_- + +Lists A.18.3(16/2) + + in Ada.Containers.Hashed_Maps + +A.18.5(16/2) + + in Ada.Containers.Hashed_Sets + +A.18.8(17/2) + +Index + +13 December 2012 904 + + + + Ada Reference Manual — 2012 Edition + + in Ada.Containers.Indefinite_Holders + +A.18.18(14/3) + + in Ada.Containers.Multiway_Trees + +A.18.10(26/3) + + in Ada.Containers.Ordered_Maps + +A.18.6(15/2) + + in Ada.Containers.Ordered_Sets + +A.18.9(16/2) + + in Ada.Containers.Vectors +A.18.2(31/2), A.18.2(32/2) + +Question + in Ada.Characters.Latin_1 A.3.3(10) +Queue + in + +Ada.Containers.Bounded_Priority_Qu +eues A.18.31(4/3) + + in + +Ada.Containers.Bounded_Synchronize +d_Queues A.18.29(4/3) + + in + +Ada.Containers.Synchronized_Queue_ +Interfaces A.18.27(4/3) + + in + +Ada.Containers.Unbounded_Priority_ +Queues A.18.30(4/3) + + in + +Ada.Containers.Unbounded_Synchron +ized_Queues A.18.28(4/3) +queuing policy D.4(1/3), D.4(6) + FIFO_Queuing D.4(7/2) + Priority_Queuing D.4(8) +Queuing_Policy pragma D.4(3), L(29) +Quotation + in Ada.Characters.Latin_1 A.3.3(8) +quotation mark 2.1(15/3) +quoted string + See string_literal 2.6(1) + +R + +raise + an exception 11(1/3) + an exception 11.3(4/2) + an exception N(18) + an exception occurrence 11.4(3) +Raise_Exception + in Ada.Exceptions 11.4.1(4/3) +raise_statement 11.3(2/2) + used 5.1(4/2), P +Random + in Ada.Numerics.Discrete_Random + +A.5.2(20) + + in Ada.Numerics.Float_Random + +A.5.2(8) + +random number A.5.2(1) +range 3.5(3), 3.5(4) + of a scalar subtype 3.5(7) + used 3.5(2), 3.6(6), 3.6.1(3), 3.8.1(5/3), + +Range(N) attribute 3.6.2(8) +range_attribute_designator 4.1.4(5) + used 4.1.4(4), P +range_attribute_reference 4.1.4(4) + used 3.5(3), P +Range_Check 11.5(17) + [partial] 3.2.2(11), 3.5(24), 3.5(27), + +3.5(39.12/3), 3.5(39.4/3), 3.5(39.5/3), +3.5(43/3), 3.5(55/3), 3.5.5(7), +3.5.9(19), 4.2(11), 4.3.3(28), 4.5.1(8), +4.5.6(6), 4.5.6(13), 4.6(28), 4.6(38), +4.6(46), 4.6(51/3), 4.7(4), +13.13.2(35/3), A.5.2(39), A.5.3(26), +A.5.3(29), A.5.3(50), A.5.3(53), +A.5.3(59), A.5.3(62), K.2(11), +K.2(114), K.2(122), K.2(184), +K.2(220), K.2(241), K.2(41), K.2(47) + +range_constraint 3.5(2) + used 3.2.2(6), 3.5.9(5), J.3(2), P +Ravenscar D.13(1/3) +RCI + generic E.2.3(7/3) + library unit E.2.3(7/3) + package E.2.3(7/3) +Re + in Ada.Numerics.Generic_Complex_- +Arrays G.3.2(7/2), G.3.2(27/2) + in Ada.Numerics.Generic_Complex_- + +Types G.1.1(6) + +re-raise statement 11.3(3) +read + the value of an object 3.3(14) + in Ada.Direct_IO A.8.4(12) + in Ada.Sequential_IO A.8.1(12) + in Ada.Storage_IO A.9(6) + in Ada.Streams 13.13.1(5) + in Ada.Streams.Stream_IO A.12.1(15), + +A.12.1(16) + + in System.RPC E.5(7) +Read aspect 13.13.2(38/3) +Read attribute 13.13.2(6), 13.13.2(14) +Read clause 13.3(7/2), 13.13.2(38/3) +ready + a task state 9(10) +ready queue D.2.1(5/2) +ready task D.2.1(5/2) +Real + in Interfaces.Fortran B.5(6) +real literal 2.4(1) +real literals 3.5.6(4) +real time D.8(18) +real type 3.2(3), 3.5.6(1), N(34) +real-time systems C(1), D(1) +Real_Arrays + child of Ada.Numerics G.3.1(31/2) +Real_Matrix + in Ada.Numerics.Generic_Real_Arrays + +Real_Time + child of Ada D.8(3) +real_type_definition 3.5.6(2) + used 3.2.1(4/2), P +Real_Vector + in Ada.Numerics.Generic_Real_Arrays + +G.3.1(4/2) + +receiving stub E.4(10) +reclamation of storage 13.11.2(1) +recommended level of support 13.1(20/3) + Address attribute 13.3(15) + Alignment attribute for objects + +13.3(33) + + Alignment attribute for subtypes + +13.3(29) + + aspect Pack 13.2(7/3) + bit ordering 13.5.3(7) + Component_Size attribute 13.3(71) + enumeration_representation_clause + +13.4(9) + + record_representation_clause + +13.5.1(17) + + required in Systems Programming + +Annex C.2(2/3) + + Size attribute 13.3(42/2), 13.3(54) + Stream_Size attribute 13.13.2(1.7/2) + unchecked conversion 13.9(16) + with respect to nonstatic expressions + +13.1(21/3) +record 3.8(1) + explicitly limited 3.8(13.1/3) +record extension 3.4(5/2), 3.9.1(1/2), + +N(35) + +Record layout aspect 13.5(1) +record type 3.8(1), N(36) +record_aggregate 4.3.1(2) + used 4.3(2), P +record_component_association 4.3.1(4/2) + used 4.3.1(3), P +record_component_association_list + +4.3.1(3) + + used 4.3.1(2), 4.3.2(2), P +record_definition 3.8(3) + used 3.8(2), 3.9.1(2), P +record_extension_part 3.9.1(2) + used 3.4(2/2), P +record_representation_clause 13.5.1(2) + used 13.1(2/1), P +record_type_definition 3.8(2) + used 3.2.1(4/2), P +reentrant A(3/2) +Reference + in Ada.Containers.Doubly_Linked_- + +Lists A.18.3(17.4/3) + + in Ada.Containers.Hashed_Maps +A.18.5(17.4/3), A.18.5(17.6/3) + in Ada.Containers.Indefinite_Holders + +G.3.1(4/2) + +A.18.18(19/3) + +4.4(3.2/3), P + +Range attribute 3.5(14), 3.6.2(7) + +real_range_specification 3.5.7(3) + used 3.5.7(2), 3.5.9(3), 3.5.9(4), P + + in Ada.Containers.Multiway_Trees + +A.18.10(31/3) + +905 13 December 2012 + +Index + + + + Ada Reference Manual — 2012 Edition + + in Ada.Containers.Ordered_Maps +A.18.6(16.4/3), A.18.6(16.6/3) + + in Ada.Containers.Vectors + +A.18.2(34.4/3), A.18.2(34.6/3) + + in Ada.Interrupts C.3.2(10) + in Ada.Task_Attributes C.7.2(5) +reference discriminant 4.1.5(3/3) +reference object 4.1.5(3/3) +reference parameter passing 6.2(2) +reference type 4.1.5(3/3), N(36.1/3) +Reference_Preserving_Key + in Ada.Containers.Hashed_Sets +A.18.8(58.2/3), A.18.8(58.4/3) + in Ada.Containers.Ordered_Sets +A.18.9(73.2/3), A.18.9(73.4/3) + +Reference_Type + in Ada.Containers.Doubly_Linked_- + +Lists A.18.3(17.2/3) + + in Ada.Containers.Hashed_Maps + +A.18.5(17.2/3) + + in Ada.Containers.Hashed_Sets + +A.18.8(58.1/3) + + in Ada.Containers.Indefinite_Holders + +A.18.18(17/3) + + in Ada.Containers.Multiway_Trees + +A.18.10(29/3) + + in Ada.Containers.Ordered_Maps + +A.18.6(16.2/3) + + in Ada.Containers.Ordered_Sets + +A.18.9(73.1/3) + + in Ada.Containers.Vectors + +A.18.2(34.2/3) +references 1.2(1/3) +Registered_Trade_Mark_Sign + in Ada.Characters.Latin_1 A.3.3(21/3) +Reinitialize + in Ada.Task_Attributes C.7.2(6) +relation 4.4(3/3) + used 4.4(2), P +relational operator 4.5.2(1) +relational_operator 4.5(3) + used 4.4(2.2/3), 4.4(3/3), P +Relative_Deadline aspect D.2.6(9.2/3) +Relative_Deadline pragma J.15.12(2/3), + +L(29.2/3) +Relative_Name + in + +Ada.Directories.Hierarchical_File_Na +mes A.16.1(13/3) +relaxed mode G.2(1) +release + execution resource associated with + +protected object 9.5.1(6) +rem operator 4.4(1/3), 4.5.5(1) +Remainder attribute A.5.3(45) +remote access E.1(5) +remote access type E.2.2(9/3) +remote access-to-class-wide type + +E.2.2(9/3) + +remote access-to-subprogram type + +E.2.2(9/3) + +remote call interface E.2(4/3), E.2.3(7/3) +remote procedure call + asynchronous E.4.1(9/3) +remote subprogram E.2.3(7/3) +remote subprogram binding E.4(1) +remote subprogram call E.4(1) +remote types library unit E.2(4/3), + +E.2.2(4/3) + +Remote_Call_Interface aspect E.2.3(7/3) +Remote_Call_Interface pragma E.2.3(3), + +L(30) + +Remote_Types aspect E.2.2(4/3) +Remote_Types pragma E.2.2(3), L(31) +Remove_Task + in + +Ada.Execution_Time.Group_Budgets +D.14.2(8/2) + +Replace_Slice + in Ada.Strings.Bounded A.4.4(58), + +A.4.4(59) + + in Ada.Strings.Fixed A.4.3(23), + +A.4.3(24) + + in Ada.Strings.Unbounded A.4.5(53), + +A.4.5(54) + +Replenish + in + +Ada.Execution_Time.Group_Budgets +D.14.2(9/2) + +Replicate + in Ada.Strings.Bounded A.4.4(78), + +A.4.4(79), A.4.4(80) + +representation + change of 13.6(1/3) +representation aspect 13.1(8/3) + coding 13.4(7) + convention, calling convention + +Rename + in Ada.Directories A.16(12/2) +renamed entity 8.5(3) +renamed view 8.5(3) +renaming N(36.2/2) +renaming-as-body 8.5.4(1/3) +renaming-as-declaration 8.5.4(1/3) +renaming_declaration 8.5(2) + used 3.1(3/3), P +rendezvous 9.5.2(25) +Replace + in Ada.Containers.Hashed_Maps + +A.18.5(23/2) + + in Ada.Containers.Hashed_Sets +A.18.8(22/2), A.18.8(53/2) + in Ada.Containers.Ordered_Maps + +A.18.6(22/2) + + in Ada.Containers.Ordered_Sets +A.18.9(21/2), A.18.9(66/2) + +Replace_Element + in Ada.Containers.Doubly_Linked_- + +Lists A.18.3(15/2) + + in Ada.Containers.Hashed_Maps + +A.18.5(15/2) + + in Ada.Containers.Hashed_Sets + +A.18.8(16/2) + + in Ada.Containers.Indefinite_Holders + +A.18.18(13/3) + + in Ada.Containers.Multiway_Trees + +A.18.10(25/3) + + in Ada.Containers.Ordered_Maps + +A.18.6(14/2) + + in Ada.Containers.Ordered_Sets + +A.18.9(15/2) + + in Ada.Containers.Vectors +A.18.2(29/2), A.18.2(30/2) + + in Ada.Strings.Bounded A.4.4(27) + in Ada.Strings.Unbounded A.4.5(21) + +B.1(1/3) + + export B.1(1/3) + external_name B.1(1/3) + import B.1(1/3) + layout 13.5(1) + link_name B.1(1/3) + record layout 13.5(1) + specifiable attributes 13.3(5/3) + storage place 13.5(1) +representation attribute 13.3(1/1) +representation item 13.1(1/1) +representation of an object 13.1(7/2) +representation pragma 13.1(1/1) + Asynchronous J.15.13(1/3) + Atomic J.15.8(9/3) + Atomic_Components J.15.8(9/3) + Convention J.15.5(1/3) + Discard_Names C.5(6) + Export J.15.5(1/3) + Import J.15.5(1/3) + Independent J.15.8(9/3) + Independent_Components J.15.8(9/3) + No_Return J.15.2(1/3) + Pack J.15.3(1/3) + Unchecked_Union J.15.6(1/3) + Volatile J.15.8(9/3) + Volatile_Components J.15.8(9/3) +representation-oriented attributes + of a fixed point subtype A.5.4(1) + of a floating point subtype A.5.3(1) +representation_clause + See aspect_clause 13.1(4/1) +represented in canonical form A.5.3(10) +requested decimal precision + of a floating point type 3.5.7(4) +requeue 9.5.4(1) +requeue target 9.5.4(3/3) +requeue-with-abort 9.5.4(13) +requeue_statement 9.5.4(2/3) + used 5.1(4/2), P +require overriding 3.9.3(6/2) + +Index + +13 December 2012 906 + + Ada Reference Manual — 2012 Edition + +requires a completion 3.11.1(1/3), + +3.11.1(6/3) + + declaration for which aspect + +restrictions + Immediate_Reclamation H.4(10) + Max_Asynchronous_Select_Nesting + +Elaborate_Body is True 10.2.1(25/3) + +D.7(18/1) + + declaration of a partial view 7.3(4) + declaration to which a pragma + +Elaborate_Body applies 10.2.1(25/3) + deferred constant declaration 7.4(2/3) + generic_package_declaration 7.1(5/2) + generic_subprogram_declaration + +6.1(20/3) + + incomplete_type_declaration + +3.10.1(3/3) + + package_declaration 7.1(5/2) + protected entry_declaration 9.5.2(16) + protected_declaration 9.4(11.2/2) + subprogram_declaration 6.1(20/3) + task_declaration 9.1(9.3/2) +requires late initialization 3.3.1(8.1/2) +requires overriding + [partial] 6.1.1(16/3) +Reraise_Occurrence + in Ada.Exceptions 11.4.1(4/3) +Reserve_Capacity + in Ada.Containers.Hashed_Maps + +A.18.5(9/2) + + in Ada.Containers.Hashed_Sets + +A.18.8(11/2) + + Max_Entry_Queue_Length D.7(19.1/2) + Max_Protected_Entries D.7(14) + Max_Select_Alternatives D.7(12) + Max_Storage_At_Blocking D.7(17/1) + Max_Task_Entries D.7(13) + Max_Tasks D.7(19/1) + No_Abort_Statements D.7(5/3) + No_Access_Parameter_Allocators + +H.4(8.3/3) + + No_Access_Subprograms H.4(17) + No_Allocators H.4(7) + No_Anonymous_Allocators H.4(8.1/3) + No_Asynchronous_Control J.13(3/2) + No_Coextensions H.4(8.2/3) + No_Delay H.4(21) + No_Dependence 13.12.1(6/2) + No_Dispatch H.4(19) + No_Dynamic_Attachment D.7(10/3) + No_Dynamic_Priorities D.7(9/2) + No_Exceptions H.4(12) + No_Fixed_Point H.4(15) + No_Floating_Point H.4(14) + No_Implementation_Aspect_Specificati + +ons 13.12.1(1.1/3) + + in Ada.Containers.Vectors + + No_Implementation_Attributes + +A.18.2(20/2) + +13.12.1(2/2) + +reserved interrupt C.3(2) +reserved word 2.9(2/3) +Reserved_128 + in Ada.Characters.Latin_1 A.3.3(17) +Reserved_129 + in Ada.Characters.Latin_1 A.3.3(17) +Reserved_132 + in Ada.Characters.Latin_1 A.3.3(17) +Reserved_153 + in Ada.Characters.Latin_1 A.3.3(19) +Reserved_Check + [partial] C.3.1(10/3) +Reset + in Ada.Direct_IO A.8.4(8) + in Ada.Numerics.Discrete_Random + + No_Implementation_Identifiers + +13.12.1(2.1/3) + + No_Implementation_Pragmas + +13.12.1(3/2) + + No_Implementation_Units + +13.12.1(3.1/3) + + No_Implicit_Heap_Allocations D.7(8) + No_IO H.4(20/2) + No_Local_Allocators H.4(8/1) + No_Local_Protected_Objects + +D.7(10.1/3) + + No_Local_Timing_Events D.7(10.2/3) + No_Nested_Finalization D.7(4/3) + No_Obsolescent_Features 13.12.1(4/3) + No_Protected_Type_Allocators + + No_Task_Termination D.7(15.1/2) + No_Terminate_Alternatives D.7(6) + No_Unchecked_Access H.4(18) + No_Unchecked_Conversion J.13(4/2) + No_Unchecked_Deallocation J.13(5/2) + No_Use_Of_Attribute 13.12.1(6.2/3) + No_Use_Of_Pragma 13.12.1(6.3/3) + Simple_Barriers D.7(10.9/3) +Restrictions pragma 13.12(3), L(32) +Result attribute 6.1.1(29/3) +result interval + for a component of the result of + +evaluating a complex function +G.2.6(3) + + for the evaluation of a predefined +arithmetic operation G.2.1(8) + for the evaluation of an elementary + +function G.2.4(2) + +result subtype + of a function 6.5(3/2) +return object + extended_return_statement 6.5(5.10/3) + simple_return_statement 6.5(6/2) +return statement 6.5(1/2) +return_subtype_indication 6.5(2.3/2) + used 6.5(2.1/3), P +reverse iterator 5.5.2(4/3) +Reverse_Elements + in Ada.Containers.Doubly_Linked_- + +Lists A.18.3(27/2) + in Ada.Containers.Vectors + +A.18.2(54/2) + +Reverse_Find + in Ada.Containers.Doubly_Linked_- + +Lists A.18.3(42/2) + in Ada.Containers.Vectors + +A.18.2(70/2) +Reverse_Find_Index + in Ada.Containers.Vectors + +A.18.2(69/2) +Reverse_Iterate + in Ada.Containers.Doubly_Linked_- + +Lists A.18.3(46/2) + + in Ada.Containers.Ordered_Maps + +A.18.6(51/2) + +A.5.2(21), A.5.2(24) + +D.7(10.3/2) + + in Ada.Containers.Ordered_Sets + + in Ada.Numerics.Float_Random + +A.5.2(9), A.5.2(12) + + in Ada.Sequential_IO A.8.1(8) + in Ada.Streams.Stream_IO A.12.1(10) + in Ada.Text_IO A.10.1(11) +resolution rules 1.1.2(26/3) +resolve + overload resolution 8.6(14) +restriction 13.12(4/2) + used 13.12(3), L(32) +restriction_parameter_argument + +13.12(4.1/2) + used 13.12(4/2), P + + No_Protected_Types H.4(5) + No_Recursion H.4(22) + No_Reentrancy H.4(23) + No_Relative_Delay D.7(10.5/3) + No_Requeue_Statements D.7(10.6/3) + No_Select_Statements D.7(10.7/3) + No_Specific_Termination_Handlers + +D.7(10.8/3) + + No_Specification_of_Aspect + +13.12.1(6.1/3) + +A.18.9(61/2) + + in Ada.Containers.Vectors + +A.18.2(74/2) + +Reverse_Iterate_Children + in Ada.Containers.Multiway_Trees + +A.18.10(69/3) +Reverse_Solidus + in Ada.Characters.Latin_1 A.3.3(12) +reversible iterable container object + +5.5.1(11/3) + + No_Standard_Allocators_After_Elabora + +reversible iterable container type + +tion D.7(19.2/3) + +5.5.1(11/3) + + No_Task_Allocators D.7(7) + No_Task_Hierarchy D.7(3/3) + +reversible iterator object 5.5.1(6/3) +reversible iterator type 5.5.1(6/3) + +907 13 December 2012 + +Index + + Ada Reference Manual — 2012 Edition + +Reversible_Iterator + in Ada.Iterator_Interfaces 5.5.1(4/3) +Reviewable pragma H.3.1(3), L(33) +RI + in Ada.Characters.Latin_1 A.3.3(17) +right parenthesis 2.1(15/3) +Right_Angle_Quotation + in Ada.Characters.Latin_1 A.3.3(22) +Right_Curly_Bracket + in Ada.Characters.Latin_1 A.3.3(14) +Right_Parenthesis + in Ada.Characters.Latin_1 A.3.3(8) +Right_Square_Bracket + in Ada.Characters.Latin_1 A.3.3(12) +Ring_Above + in Ada.Characters.Latin_1 A.3.3(22) +root + of a tree A.18.10(3/3) + in Ada.Containers.Multiway_Trees + +A.18.10(22/3) + +root library unit 10.1.1(10) +root node + of a tree A.18.10(3/3) +root type + of a class 3.4.1(2/2) +root_integer 3.5.4(14) + [partial] 3.4.1(8) +root_real 3.5.6(3) + [partial] 3.4.1(8) +Root_Storage_Pool + in System.Storage_Pools 13.11(6/2) +Root_Storage_Pool_With_Subpools + in System.Storage_Pools.Subpools + +13.11.4(4/3) +Root_Stream_Type + in Ada.Streams 13.13.1(3/2) +Root_Subpool + in System.Storage_Pools.Subpools + +13.11.4(5/3) + +rooted at a type 3.4.1(2/2) +roots the subtree A.18.10(3/3) +rotate B.2(9) +Round attribute 3.5.10(12) +Round_Robin + child of Ada.Dispatching D.2.5(4/2) +Round_Robin_Within_Priorities task +dispatching policy D.2.5(2/2) + +Rounding attribute A.5.3(36) +RPC + child of System E.5(3) +RPC-receiver E.5(21) +RPC_Receiver + in System.RPC E.5(11) +RS + in Ada.Characters.Latin_1 A.3.3(6) +run-time check + See language-defined check 11.5(2/3) +run-time error 1.1.2(30), 1.1.5(6), + +run-time semantics 1.1.2(30) +run-time type + See tag 3.9(3) +running a program + See program execution 10.2(1) +running task D.2.1(6/2) + +S + +safe range + of a floating point type 3.5.7(9) + of a floating point type 3.5.7(10) +Safe_First attribute A.5.3(71), G.2.2(5) +Safe_Last attribute A.5.3(72), G.2.2(6) +safety-critical systems H(1/2) +satisfies + a discriminant constraint 3.7.1(11) + a range constraint 3.5(4) + a subtype predicate 3.2.4(32/3) + an index constraint 3.6.1(7) + for an access value 3.10(15/2) +Saturday + in Ada.Calendar.Formatting + +9.6.1(17/2) + +Save + in Ada.Numerics.Discrete_Random + +A.5.2(24) + + in Ada.Numerics.Float_Random + +A.5.2(12) +Save_Occurrence + in Ada.Exceptions 11.4.1(6/2) +scalar type 3.2(3), 3.5(1), N(37) +scalar_constraint 3.2.2(6) + used 3.2.2(5), P +scale + of a decimal fixed point subtype + +3.5.10(11), K.2(216) +Scale attribute 3.5.10(11) +Scaling attribute A.5.3(27) +SCHAR_MAX + in Interfaces.C B.3(6) +SCHAR_MIN + in Interfaces.C B.3(6) +SCI + in Ada.Characters.Latin_1 A.3.3(19) +scope + informal definition 3.1(8) + of (a view of) an entity 8.2(11) + of a declaration 8.2(10) + of a use_clause 8.4(6) + of a with_clause 10.1.2(5) + of an aspect_specification 8.2(10.1/3) + of an attribute_definition_clause + +8.2(10.1/3) + +Search_Type + in Ada.Directories A.16(31/2) +Second + in Ada.Calendar.Formatting + +11.5(2/3), 11.6(1/3) + +9.6.1(26/2) + +run-time polymorphism 3.9.2(1/2) + +Second_Duration subtype of + +Day_Duration + + in Ada.Calendar.Formatting + +9.6.1(20/2) + +Second_Number subtype of Natural + in Ada.Calendar.Formatting + +9.6.1(20/2) + +Seconds + in Ada.Calendar 9.6(13) + in Ada.Real_Time D.8(14/2) +Seconds_Count + in Ada.Real_Time D.8(15) +Seconds_Of + in Ada.Calendar.Formatting + +9.6.1(28/2) + +Section_Sign + in Ada.Characters.Latin_1 A.3.3(21/3) +secure systems H(1/2) +select an entry call + from an entry queue 9.5.3(13), + +9.5.3(16) + + immediately 9.5.3(8) +select_alternative 9.7.1(4) + used 9.7.1(2), P +select_statement 9.7(2) + used 5.1(5/2), P +selected_component 4.1.3(2) + used 4.1(2/3), P +selection + of an entry caller 9.5.2(24) +selective_accept 9.7.1(2) + used 9.7(2), P +selector_name 4.1.3(3) + used 3.7.1(3), 4.1.3(2), 4.3.1(5), 6.4(5), + +12.3(4), 12.7(3.1/2), P + +semantic dependence + of one compilation unit upon another + +10.1.1(26/2) +semicolon 2.1(15/3) + in Ada.Characters.Latin_1 A.3.3(10) +separate compilation 10.1(1) +Separate_Interrupt_Clocks_Supported + in Ada.Execution_Time D.14(9.2/3) +separator 2.2(3/2) +separator_line 2.1(12/2) +separator_paragraph 2.1(12.1/2) +separator_space 2.1(11/2) +sequence of characters + of a string_literal 2.6(5) +sequence_of_statements 5.1(2/3) + used 5.3(2), 5.4(3), 5.5(2), 9.7.1(2), + +9.7.1(5), 9.7.1(6), 9.7.2(3/2), 9.7.3(2), +9.7.4(3), 9.7.4(5), 11.2(2), 11.2(3), P + +sequential + actions 9.10(11), C.6(17) +sequential access A.8(2) +sequential file A.8(1/2) +Sequential_IO + child of Ada A.8.1(2) + +Index + +13 December 2012 908 + + + + Ada Reference Manual — 2012 Edition + +service + an entry queue 9.5.3(13) +set + execution timer object D.14.1(12/2) + group budget object D.14.2(15/2) + termination handler C.7.3(9/2) + timing event object D.15(9/2) + in Ada.Containers.Hashed_Sets + +A.18.8(3/3) + + in Ada.Containers.Ordered_Sets + +A.18.9(4/3) + + in Ada.Environment_Variables + +A.17(6/2) + +set container A.18.7(1/2) +Set_Bounded_String + in Ada.Strings.Bounded A.4.4(12.1/2) +Set_Col + in Ada.Text_IO A.10.1(35) +Set_CPU + in + +System.Multiprocessors.Dispatching_ +Domains D.16.1(12/3) + +Set_Deadline + in Ada.Dispatching.EDF D.2.6(9/2) +Set_Dependents_Fallback_Handler + in Ada.Task_Termination C.7.3(5/2) +Set_Directory + in Ada.Directories A.16(6/2) +Set_Error + in Ada.Text_IO A.10.1(15) +Set_Exit_Status + in Ada.Command_Line A.15(9) +Set_False + in Ada.Synchronous_Task_Control + +D.10(4) +Set_Handler + in + +Set_Length + in Ada.Containers.Vectors + +A.18.2(22/2) + +Set_Line + in Ada.Text_IO A.10.1(36) +Set_Line_Length + in Ada.Text_IO A.10.1(23) +Set_Mode + in Ada.Streams.Stream_IO A.12.1(24) +Set_Output + in Ada.Text_IO A.10.1(15) +Set_Page_Length + in Ada.Text_IO A.10.1(24) +Set_Pool_of_Subpool + in System.Storage_Pools.Subpools + +13.11.4(10/3) + +Set_Priority + in Ada.Dynamic_Priorities D.5.1(4) +Set_Quantum + in Ada.Dispatching.Round_Robin + +D.2.5(4/2) + +Set_Re + in Ada.Numerics.Generic_Complex_- +Arrays G.3.2(8/2), G.3.2(28/2) + in Ada.Numerics.Generic_Complex_- + +Types G.1.1(7) +Set_Specific_Handler + in Ada.Task_Termination C.7.3(6/2) +Set_True + in Ada.Synchronous_Task_Control + +D.10(4) + +Set_Unbounded_String + in Ada.Strings.Unbounded + +A.4.5(11.1/2) + +Set_Value + in Ada.Task_Attributes C.7.2(6) +shared passive library unit E.2(4/3), + +Ada.Execution_Time.Group_Budgets +D.14.2(10/2) + + in Ada.Execution_Time.Timers + +D.14.1(7/2) + + in Ada.Real_Time.Timing_Events + +D.15(5/2) + +Set_Im + in Ada.Numerics.Generic_Complex_- +Arrays G.3.2(8/2), G.3.2(28/2) + in Ada.Numerics.Generic_Complex_- + +Types G.1.1(7) + +Set_Index + in Ada.Direct_IO A.8.4(14) + in Ada.Streams.Stream_IO A.12.1(22) +Set_Input + in Ada.Text_IO A.10.1(15) +Set_Iterator_Interfaces + in Ada.Containers.Hashed_Sets + +A.18.8(6.2/3) + + in Ada.Containers.Ordered_Sets + +A.18.9(7.2/3) + +E.2.1(4/3) +shared variable + protection of 9.10(1/3) +Shared_Passive aspect E.2.1(4/3) +Shared_Passive pragma E.2.1(3), L(34) +shift B.2(9) +short + in Interfaces.C B.3(7) +short-circuit control form 4.5.1(1) +Short_Float 3.5.7(16) +Short_Integer 3.5.4(25) +SI + in Ada.Characters.Latin_1 A.3.3(5) +signal + as defined between actions 9.10(2) + See interrupt C.3(1/3) +signal (an exception) + See raise 11(1/3) +signal handling + example 9.7.4(10) +signed integer type 3.5.4(1) +signed_char + in Interfaces.C B.3(8) + +signed_integer_type_definition 3.5.4(3) + used 3.5.4(2), P +Signed_Zeros attribute A.5.3(13) +simple entry call 9.5.3(1) +simple name + of a file A.16(47/2) +Simple_Barriers restriction D.7(10.9/3) +simple_expression 4.4(4) + used 3.5(3), 3.5.4(3), 3.5.7(3), +4.4(2.2/3), 4.4(3/3), 13.5.1(5), +13.5.1(6), P + +Simple_Name + in Ada.Directories A.16(16/2), + +A.16(38/2) + + in + +Ada.Directories.Hierarchical_File_Na +mes A.16.1(10/3) + +simple_return_statement 6.5(2/2) + used 5.1(4/2), P +simple_statement 5.1(4/2) + used 5.1(3), P +Sin + in Ada.Numerics.Generic_Complex_- +Elementary_Functions G.1.2(4) + in Ada.Numerics.Generic_Elementary_- + +Functions A.5.1(5) + +single + class expected type 8.6(27/2) +single entry 9.5.2(20) +Single_Precision_Complex_Types + in Interfaces.Fortran B.5(8) +single_protected_declaration 9.4(3/3) + used 3.3.1(2/3), P +single_task_declaration 9.1(3/3) + used 3.3.1(2/3), P +Sinh + in Ada.Numerics.Generic_Complex_- +Elementary_Functions G.1.2(6) + in Ada.Numerics.Generic_Elementary_- + +Functions A.5.1(7) + +size + of an object 13.1(7/2) + in Ada.Direct_IO A.8.4(15) + in Ada.Directories A.16(26/2), + +A.16(41/2) + + in Ada.Streams.Stream_IO A.12.1(23) +Size (object) aspect 13.3(41) +Size (subtype) aspect 13.3(48) +Size attribute 13.3(40), 13.3(45) +Size clause 13.3(7/2), 13.3(41), 13.3(48) +size_t + in Interfaces.C B.3(13) +Skip_Line + in Ada.Text_IO A.10.1(29) +Skip_Page + in Ada.Text_IO A.10.1(32) +slice 4.1.2(2) + used 4.1(2/3), P + in Ada.Strings.Bounded A.4.4(28) + in Ada.Strings.Unbounded A.4.5(22) + +909 13 December 2012 + +Index + + Ada Reference Manual — 2012 Edition + +small + of a fixed point type 3.5.9(8/2) +Small aspect 3.5.10(2/1) +Small attribute 3.5.10(2/1) +Small clause 3.5.10(2/1), 13.3(7/2) +SO + in Ada.Characters.Latin_1 A.3.3(5) +Soft_Hyphen + in Ada.Characters.Latin_1 A.3.3(21/3) +SOH + in Ada.Characters.Latin_1 A.3.3(5) +solidus 2.1(15/3) + in Ada.Characters.Latin_1 A.3.3(8) +Solve + in Ada.Numerics.Generic_Complex_- + +Arrays G.3.2(46/2) + + in Ada.Numerics.Generic_Real_Arrays + +G.3.1(24/2) + +Sort + in Ada.Containers.Doubly_Linked_- + +Lists A.18.3(49/2) + in Ada.Containers.Vectors + +A.18.2(77/2) + +SOS + in Ada.Characters.Latin_1 A.3.3(19) +SPA + in Ada.Characters.Latin_1 A.3.3(18) +Space + in Ada.Characters.Latin_1 A.3.3(8) + in Ada.Strings A.4.1(4/2) +special file A.16(45/2) +special graphic character + a category of Character A.3.2(32) +Special_Set + in Ada.Strings.Maps.Constants + +A.4.6(4) + +Specialized Needs Annexes 1.1.2(7) +specifiable + of Address for entries J.7.1(6) + of Address for stand-alone objects and + +for program units 13.3(12) + of Alignment for first subtypes + +13.3(26.4/2) + + of Alignment for objects 13.3(25/2) + of Bit_Order for record types and record + +extensions 13.5.3(4) + + of Component_Size for array types + + of Storage_Pool for a nonderived +access-to-object type 13.11(15) + of Storage_Size for a nonderived access- + +to-object type 13.11(15) + + of Storage_Size for a task first subtype + +J.9(3/3) + + of Write for a type 13.13.2(38/3) +specifiable (of an attribute and for an + +entity) 13.3(5/3) + +specific handler C.7.3(9/2) +specific postcondition expression + +6.1.1(4/3) + +specific precondition expression + +6.1.1(2/3) + +specific type 3.4.1(3/2) +Specific_Handler + in Ada.Task_Termination C.7.3(6/2) +specified + of an aspect of representation of an + +entity 13.1(17) + + of an operational aspect of an entity + +13.1(18.1/1) + +specified (not!) 1.1.3(18) +specified as independently addressable + +C.6(8.1/3) + +specified discriminant 3.7(18) +Splice + in Ada.Containers.Doubly_Linked_- +Lists A.18.3(30/2), A.18.3(31/2), +A.18.3(32/2) +Splice_Children + in Ada.Containers.Multiway_Trees +A.18.10(57/3), A.18.10(58/3) + +Splice_Subtree + in Ada.Containers.Multiway_Trees +A.18.10(55/3), A.18.10(56/3) + +Split + in Ada.Calendar 9.6(14) + in Ada.Calendar.Formatting + +9.6.1(29/2), 9.6.1(32/2), 9.6.1(33/2), +9.6.1(34/2) + + in Ada.Execution_Time D.14(8/2) + in Ada.Real_Time D.8(16) +Sqrt + in Ada.Numerics.Generic_Complex_- +Elementary_Functions G.1.2(3) + in Ada.Numerics.Generic_Elementary_- + +13.3(70) + +Functions A.5.1(4) + + of External_Tag for a tagged type + +13.3(75/3), K.2(65) + + of Input for a type 13.13.2(38/3) + of Machine_Radix for decimal first + +subtypes F.1(1) + + of Output for a type 13.13.2(38/3) + of Read for a type 13.13.2(38/3) + of Size for first subtypes 13.3(48) + of Size for stand-alone objects 13.3(41) + of Small for fixed point types + +SS2 + in Ada.Characters.Latin_1 A.3.3(17) +SS3 + in Ada.Characters.Latin_1 A.3.3(17) +SSA + in Ada.Characters.Latin_1 A.3.3(17) +ST + in Ada.Characters.Latin_1 A.3.3(19) +stand-alone constant 3.3.1(23/3) + corresponding to a formal object of + +3.5.10(2/1) + +Index + +mode in 12.4(10/2) +stand-alone object 3.3.1(1/3) + + [partial] 12.4(10/2) +stand-alone variable 3.3.1(23/3) +Standard A.1(4) +standard error file A.10(6) +standard input file A.10(5) +standard mode 1.1.5(11) +standard output file A.10(5) +standard storage pool 13.11(17) +Standard_Error + in Ada.Text_IO A.10.1(16), A.10.1(19) +Standard_Input + in Ada.Text_IO A.10.1(16), A.10.1(19) +Standard_Output + in Ada.Text_IO A.10.1(16), A.10.1(19) +Start_Search + in Ada.Directories A.16(32/2) +State + in Ada.Numerics.Discrete_Random + +A.5.2(23) + + in Ada.Numerics.Float_Random + +A.5.2(11) +statement 5.1(3) + used 5.1(2/3), P +statement_identifier 5.1(8) + used 5.1(7), 5.5(2), 5.6(2), P +static 4.9(1) + constant 4.9(24) + constraint 4.9(27) + delta constraint 4.9(29) + digits constraint 4.9(29) + discrete_range 4.9(25) + discriminant constraint 4.9(31) + expression 4.9(2) + function 4.9(18) + index constraint 4.9(30) + range 4.9(25) + range constraint 4.9(29) + scalar subtype 4.9(26/3) + string subtype 4.9(26/3) + subtype 4.9(26/3) + subtype 12.4(9/2) +static semantics 1.1.2(28) +Static_Predicate aspect 3.2.4(1/3) +statically + constrained 4.9(32) + denote 4.9(14) +statically compatible + for a constraint and a scalar subtype + +4.9.1(4/3) + + for a constraint and an access or +composite subtype 4.9.1(4/3) + + for two subtypes 4.9.1(5/3) +statically deeper 3.10.2(4), 3.10.2(17) +statically determined tag 3.9.2(1/2) + [partial] 3.9.2(15), 3.9.2(19) +statically matching + effect on subtype-specific aspects + +13.1(14) + + for constraints 4.9.1(1/2) + for ranges 4.9.1(3) + +13 December 2012 910 + + Ada Reference Manual — 2012 Edition + + for subtypes 4.9.1(2/3) + required 3.9.2(10/2), 3.10.2(27.1/2), + +4.6(24.15/2), 4.6(24.5/2), +6.3.1(16.3/3), 6.3.1(17/3), 6.3.1(23), +6.5(5.2/3), 7.3(13), 8.5.1(4.2/2), +12.4(8.1/2), 12.5.1(14), 12.5.3(6), +12.5.3(7), 12.5.4(3), 12.7(7) + +statically tagged 3.9.2(4/2) +statically unevaluated 4.9(32.1/3) +Status_Error + in Ada.Direct_IO A.8.4(18) + in Ada.Directories A.16(43/2) + in Ada.IO_Exceptions A.13(4) + in Ada.Sequential_IO A.8.1(15) + in Ada.Streams.Stream_IO A.12.1(26) + in Ada.Text_IO A.10.1(85) +storage deallocation + unchecked 13.11.2(1) +storage element 13.3(8) +storage management + user-defined 13.11(1) +storage node E(2) +storage place + of a component 13.5(1) + representation aspect 13.5(1) +storage place attributes + of a component 13.5.2(1) +storage pool 3.10(7/1), N(37.1/3) + default 13.11.3(4.1/3) +storage pool element 13.11(11) +storage pool that supports subpools + +Storage_Pools + child of System 13.11(5) +Storage_Size + in System.Storage_Pools 13.11(9) + in System.Storage_Pools.Subpools + +13.11.4(16/3) + +Storage_Size (access) aspect 13.11(15) +Storage_Size (task) aspect 13.3(65.2/3) +Storage_Size attribute 13.3(60/3), + +13.11(14), J.9(2) + +Storage_Size clause 13.3(7/2), 13.11(15) +Storage_Size pragma J.15.4(2/3), + +L(35.1/3) +Storage_Unit + in System 13.7(13) +stream 13.13(1), N(37.2/3) + in Ada.Streams.Stream_IO A.12.1(13) + in Ada.Text_IO.Text_Streams + +A.12.2(4) + + in Ada.Wide_Text_IO.Text_Streams + +A.12.3(4) + + in Ada.Wide_Wide_Text_IO.Text_- + +Streams A.12.4(4/2) + +stream file A.8(1/2) +stream type 13.13(1) +Stream_Access + in Ada.Streams.Stream_IO A.12.1(4) + in Ada.Text_IO.Text_Streams + +A.12.2(3) + + in Ada.Wide_Text_IO.Text_Streams + +A.12.3(3) + +Strings + child of Ada A.4.1(3) + child of Ada.Strings.UTF_Encoding + +A.4.11(22/3) + + child of Interfaces.C B.3.1(3) +Strlen + in Interfaces.C.Strings B.3.1(17) +structure + See record type 3.8(1) +STS + in Ada.Characters.Latin_1 A.3.3(18) +STX + in Ada.Characters.Latin_1 A.3.3(5) +SUB + in Ada.Characters.Latin_1 A.3.3(6) +Sub_Second + in Ada.Calendar.Formatting + +9.6.1(27/2) + +subaggregate + of an array_aggregate 4.3.3(6) +subcomponent 3.2(6/2) +subpool 13.11.4(18/3) +subpool access type 13.11.4(22/3) +subpool handle 13.11.4(18/3) +Subpool_Handle + in System.Storage_Pools.Subpools + +13.11.4(6/3) + +subpool_specification 4.8(2.1/3) + used 4.8(2/3), P +Subpools + child of System.Storage_Pools + +13.11.4(18/3) + + in Ada.Wide_Wide_Text_IO.Text_- + +13.11.4(3/3) + +storage pool type 13.11(11) +Storage_Array + in System.Storage_Elements 13.7.1(5) +Storage_Check 11.5(23) + [partial] 11.1(6), 13.3(67), 13.11(17), +D.7(17/1), D.7(18/1), D.7(19/1) +Storage_Count subtype of Storage_Offset + in System.Storage_Elements 13.7.1(4) +Storage_Element + in System.Storage_Elements 13.7.1(5) +Storage_Elements + child of System 13.7.1(2/2) +Storage_Error + raised by failure of run-time check + +4.8(14), 8.5.4(8.1/1), 11.1(4), 11.1(6), +11.5(23), 13.3(67), 13.11(17), +13.11(18), A.7(14/3), D.7(17/1), +D.7(18/1), D.7(19.3/3), D.7(19/1) + + in Standard A.1(46) +Storage_IO + child of Ada A.9(3) +Storage_Offset + in System.Storage_Elements 13.7.1(3) +Storage_Pool aspect 13.11(15) +Storage_Pool attribute 13.11(13) +Storage_Pool clause 13.3(7/2), 13.11(15) +storage_pool_indicator 13.11.3(3.1/3) + used 13.11.3(3/3), L(8.3/3) + +Streams A.12.4(3/2) + +Stream_Element + in Ada.Streams 13.13.1(4/1) +Stream_Element_Array + in Ada.Streams 13.13.1(4/1) +Stream_Element_Count subtype of + +Stream_Element_Offset + in Ada.Streams 13.13.1(4/1) +Stream_Element_Offset + in Ada.Streams 13.13.1(4/1) +Stream_IO + child of Ada.Streams A.12.1(3/3) +Stream_Size aspect 13.13.2(1.5/2) +Stream_Size attribute 13.13.2(1.2/3) +Stream_Size clause 13.3(7/2) +Streams + child of Ada 13.13.1(2) +strict mode G.2(1) +strict weak ordering A.18(5/3) +String + in Standard A.1(37/3) +string type 3.6.3(1) +String_Access + in Ada.Strings.Unbounded A.4.5(7) +string_element 2.6(3) + used 2.6(2), P +string_literal 2.6(2) + used 4.4(7/3), 6.1(9), P + +subprogram 6(1), N(37.3/2) + abstract 3.9.3(3/2) +subprogram call 6.4(1) +subprogram instance 12.3(13) +subprogram_body 6.3(2/3) + used 3.11(6), 9.4(8/1), 10.1.1(7), P +subprogram_body_stub 10.1.3(3/3) + used 10.1.3(2), P +subprogram_declaration 6.1(2/3) + used 3.1(3/3), 9.4(5/1), 9.4(8/1), + +10.1.1(5), P + +subprogram_default 12.6(3/2) + used 12.6(2.1/3), 12.6(2.2/3), P +subprogram_renaming_declaration + +8.5.4(2/3) + + used 8.5(2), 10.1.1(6), P +subprogram_specification 6.1(4/2) + used 3.9.3(1.1/3), 6.1(2/3), 6.3(2/3), +8.5.4(2/3), 10.1.3(3/3), 12.1(3/3), +12.6(2.1/3), 12.6(2.2/3), P + +subsystem 10.1(3), N(22) +subtree + node which roots A.18.10(3/3) + of a tree A.18.10(3/3) +Subtree_Node_Count + in Ada.Containers.Multiway_Trees + +A.18.10(18/3) + +subtype 3.2(8/2), N(38/3) + +911 13 December 2012 + +Index + + Ada Reference Manual — 2012 Edition + + constraint of 3.2(8/2) + type of 3.2(8/2) + values belonging to 3.2(8/2) +subtype (of an object) + See actual subtype of an object + +3.3(23/3) + +Superscript_Two + in Ada.Characters.Latin_1 A.3.3(22) +support external streaming 13.13.2(52/3) +Supported + in Ada.Execution_Time.Interrupts + +D.14.3(3/3) + + See actual subtype of an object + +Suppress pragma 11.5(4/2), J.10(3/2), + +3.3.1(9/2) + +L(36) + +System.Machine_Code 13.8(7) +System.Multiprocessors D.16(3/3) +System.Multiprocessors.Dispatching_Do + +mains D.16.1(3/3) + +System.RPC E.5(3) +System.Storage_Elements 13.7.1(2/2) +System.Storage_Pools 13.11(5) +System.Storage_Pools.Subpools + +subtype conformance 6.3.1(17/3) + [partial] 3.10.2(34/2), 9.5.4(17) + required 3.9.2(10/2), 3.10.2(32/3), + +suppressed check 11.5(8/2) +Suspend_Until_True + in Ada.Synchronous_Task_Control + +13.11.4(3/3) + +System_Dispatching_Domain + in + +4.6(24.20/3), 8.5.1(4.3/2), 8.5.4(5/3), +9.1(9.7/2), 9.1(9.8/2), 9.4(11.6/2), +9.4(11.7/2), 9.5.4(5/3), 12.4(8.2/2), +12.5.4(5/3) +subtype conversion + See type conversion 4.6(1/3) + See also implicit subtype conversion + +4.6(1/3) +subtype-specific + of a representation item 13.1(8/3) + of an aspect 13.1(8/3) +subtype_declaration 3.2.2(2/3) + used 3.1(3/3), P +subtype_indication 3.2.2(3/2) + used 3.2.2(2/3), 3.3.1(2/3), 3.4(2/2), +3.6(6), 3.6(7/2), 3.6.1(3), 3.8.1(5/3), +3.10(3), 4.8(2/3), 5.5.2(2/3), +6.5(2.3/2), 7.3(3/3), P + +subtype_mark 3.2.2(4) + used 3.2.2(3/2), 3.6(4), 3.7(5/2), +3.9.4(3/2), 3.10(6/2), 4.3.2(3), +4.4(3.2/3), 4.6(2), 4.7(2), 6.1(13/2), +6.1(15/3), 8.4(4/3), 8.5.1(2/3), 12.3(5), +12.4(2/3), 12.5.1(3/2), P + +subtypes + of a profile 6.1(25) +subunit 10.1.3(7), 10.1.3(8/2) + of a program unit 10.1.3(8/2) + used 10.1.1(3), P +Succ attribute 3.5(22) +Success + in Ada.Command_Line A.15(8) +successor element + of a hashed set A.18.8(68/2) + of a set A.18.7(6/2) + of an ordered set A.18.9(81/3) +successor node + of a hashed map A.18.5(46/2) + of a map A.18.4(6/2) + of an ordered map A.18.6(58/3) +Sunday + in Ada.Calendar.Formatting + +9.6.1(17/2) + +super + See view conversion 4.6(5/2) +Superscript_One + in Ada.Characters.Latin_1 A.3.3(22) +Superscript_Three + in Ada.Characters.Latin_1 A.3.3(22) + +D.10(4) + +Suspend_Until_True_And_Set_Deadline + in + +Ada.Synchronous_Task_Control.EDF + D.10(5.2/3) +Suspension_Object + in Ada.Synchronous_Task_Control + +D.10(4) + +Swap + in Ada.Containers.Doubly_Linked_- + +Lists A.18.3(28/2) + + in Ada.Containers.Multiway_Trees + +A.18.10(37/3) + + in Ada.Containers.Vectors +A.18.2(55/2), A.18.2(56/2) + +Swap_Links + in Ada.Containers.Doubly_Linked_- + +Lists A.18.3(29/2) +Symmetric_Difference + in Ada.Containers.Hashed_Sets +A.18.8(35/2), A.18.8(36/2) + in Ada.Containers.Ordered_Sets +A.18.9(36/2), A.18.9(37/2) + +SYN + in Ada.Characters.Latin_1 A.3.3(6) +synchronization 9(1/3) +Synchronization aspect 9.5(12/3) +synchronization_kind 9.5(10/3) +synchronized N(38.1/2) +synchronized interface 3.9.4(5/2) +synchronized tagged type 3.9.4(6/2) +Synchronized_Queue_Interfaces + child of Ada.Containers A.18.27(3/3) +Synchronous_Barrier + in Ada.Synchronous_Barriers + +D.10.1(5/3) + +Synchronous_Barriers + child of Ada D.10.1(3/3) +Synchronous_Task_Control + child of Ada D.10(3/2) +syntactic category 1.1.4(15) +syntax + complete listing P(1) + cross reference P(1) + notation 1.1.4(3) + under Syntax heading 1.1.2(25) +System 13.7(3/2) +System.Address_To_Access_- +Conversions 13.7.2(2) + +System.Multiprocessors.Dispatching_ +Domains D.16.1(6/3) + +System_Name + in System 13.7(4) +systems programming C(1) + +T + +Tag + in Ada.Tags 3.9(6/2) +Tag attribute 3.9(16), 3.9(18) +tag indeterminate 3.9.2(6/2) +tag of an object 3.9(3) + class-wide object 3.9(22) + object created by an allocator 3.9(21) + preserved by type conversion and +parameter passing 3.9(25) + returned by a function 3.9(23), + +3.9(24/2) + + stand-alone object, component, or + +aggregate 3.9(20) + +Tag_Array + in Ada.Tags 3.9(7.3/2) +Tag_Check 11.5(18) + [partial] 3.9.2(16), 4.6(42), 4.6(52), + +5.2(10), 6.5(8.1/3) + +Tag_Error + in Ada.Tags 3.9(8) +tagged incomplete view 3.10.1(2.1/2) +tagged type 3.9(2/2), N(39) + protected 3.9.4(6/2) + synchronized 3.9.4(6/2) + task 3.9.4(6/2) +Tags + child of Ada 3.9(6/2) +Tail + in Ada.Strings.Bounded A.4.4(72), + +A.4.4(73) + + in Ada.Strings.Fixed A.4.3(37), + +A.4.3(38) + + in Ada.Strings.Unbounded A.4.5(67), + +A.4.5(68) + +tail (of a queue) D.2.1(5/2) +tamper with cursors + of a list A.18.3(62/2) + of a map A.18.4(8/2) + of a set A.18.7(8/2) + of a tree A.18.10(81/3) + of a vector A.18.2(91/2) + +Index + +13 December 2012 912 + + + + tamper with elements + of a holder A.18.18(30/3) + of a list A.18.3(67/2) + of a map A.18.4(13/2) + of a set A.18.7(13/2) + of a tree A.18.10(87/3) + of a vector A.18.2(95/2) +tampering + prohibited for a holder A.18.18(35/3) + prohibited for a list A.18.3(69.1/3) + prohibited for a map A.18.4(15.1/3) + prohibited for a set A.18.7(14.1/3) + prohibited for a tree A.18.10(90/3) + prohibited for a vector A.18.2(97.1/3) +Tan + in Ada.Numerics.Generic_Complex_- +Elementary_Functions G.1.2(4) + in Ada.Numerics.Generic_Elementary_- + +Functions A.5.1(5) + +Tanh + in Ada.Numerics.Generic_Complex_- +Elementary_Functions G.1.2(6) + in Ada.Numerics.Generic_Elementary_- + +Functions A.5.1(7) + +target + of an assignment operation 5.2(3) + of an assignment_statement 5.2(3) +target object + of a requeue_statement 9.5(7) + of the name of an entry or a protected + +subprogram 9.5(2/3) + +target statement + of a goto_statement 5.8(3) +target subtype + of a type_conversion 4.6(3) +task 9(1/3) + activation 9.2(1) + completion 9.3(1) + dependence 9.3(1) + execution 9.2(1) + termination 9.3(1) +task declaration 9.1(1) +task dispatching D.2.1(4/2) +task dispatching point D.2.1(4/2) + [partial] D.2.3(8/2), D.2.4(9/3) +task dispatching policy D.2.2(7/2) + [partial] D.2.1(5/2) + EDF_Across_Priorities D.2.6(7/2) + FIFO_Within_Priorities D.2.3(2/2) + Non_Preemptive_FIFO_Within_- + +Priorities D.2.4(2/2) + + Round_Robin_Within_Priorities + +D.2.5(2/2) + +task interface 3.9.4(5/2) +task priority D.1(15) +task state + abnormal 9.8(4) + blocked 9(10) + callable 9.9(2) + held D.11(4/2) + +Ada Reference Manual — 2012 Edition + +Text_IO + child of Ada A.10.1(2) +Text_Streams + child of Ada.Text_IO A.12.2(3) + child of Ada.Wide_Text_IO A.12.3(3) + child of Ada.Wide_Wide_Text_IO + + inactive 9(10) + ready 9(10) + terminated 9(10) +task tagged type 3.9.4(6/2) +task type N(40/2) +task unit 9(9) +Task_Array + in + +Ada.Execution_Time.Group_Budgets +D.14.2(6/2) +Task_Attributes + child of Ada C.7.2(2) +task_body 9.1(6/3) + used 3.11(6), P +task_body_stub 10.1.3(5) + used 10.1.3(2), P +task_definition 9.1(4) + used 9.1(2/3), 9.1(3/3), P +Task_Dispatching_Policy pragma + +D.2.2(3), L(37) + +Task_Id + in Ada.Task_Identification C.7.1(2/2) +Task_Identification + child of Ada C.7.1(2/2) +task_item 9.1(5/1) + used 9.1(4), P +Task_Termination + child of Ada C.7.3(2/2) +task_type_declaration 9.1(2/3) + used 3.2.1(3/3), P +Tasking_Error + raised by failure of run-time check + +9.2(5), 9.5.3(21), 11.1(4), 13.11.2(13), +13.11.2(14), C.7.2(13), D.5.1(8), +D.11(8) + + in Standard A.1(46) +template 12(1) + for a formal package 12.7(4) + See generic unit 12(1) +term 4.4(5) + used 4.4(4), P +terminal interrupt + example 9.7.4(10) +terminate_alternative 9.7.1(7) + used 9.7.1(4), P +terminated + a task state 9(10) +Terminated attribute 9.9(3) +termination + of a partition E.1(7) +termination handler C.7.3(8/3) + fall-back C.7.3(9/2) + specific C.7.3(9/2) +Termination_Handler + in Ada.Task_Termination C.7.3(4/2) +Terminator_Error + in Interfaces.C B.3(40) +tested type + of a membership test 4.5.2(3/3) +text of a program 2.2(1) + +A.12.4(3/2) +throw (an exception) + See raise 11(1/3) +Thursday + in Ada.Calendar.Formatting + +9.6.1(17/2) +tick 2.1(15/3) + in Ada.Real_Time D.8(6) + in System 13.7(10) +Tilde + in Ada.Characters.Latin_1 A.3.3(14) +Time + in Ada.Calendar 9.6(10) + in Ada.Real_Time D.8(4) +time base 9.6(6/3) +time limit + example 9.7.4(12) +time type 9.6(6/3) +Time-dependent Reset procedure + of the random number generator + +A.5.2(34) + +time-out + example 9.7.4(12) + See asynchronous_select 9.7.4(12) + See selective_accept 9.7.1(1) + See timed_entry_call 9.7.2(1/2) +Time_Error + in Ada.Calendar 9.6(18) +Time_First + in Ada.Real_Time D.8(4) +Time_Last + in Ada.Real_Time D.8(4) +Time_Of + in Ada.Calendar 9.6(15) + in Ada.Calendar.Formatting +9.6.1(30/2), 9.6.1(31/2) + + in Ada.Execution_Time D.14(9/2) + in Ada.Real_Time D.8(16) +Time_Of_Event + in Ada.Real_Time.Timing_Events + +D.15(6/2) +Time_Offset + in Ada.Calendar.Time_Zones + +9.6.1(4/2) +Time_Remaining + in Ada.Execution_Time.Timers + +D.14.1(8/2) + +Time_Span + in Ada.Real_Time D.8(5) +Time_Span_First + in Ada.Real_Time D.8(5) +Time_Span_Last + in Ada.Real_Time D.8(5) + +913 13 December 2012 + +Index + + Ada Reference Manual — 2012 Edition + +Time_Span_Unit + in Ada.Real_Time D.8(5) +Time_Span_Zero + in Ada.Real_Time D.8(5) +Time_Unit + in Ada.Real_Time D.8(4) +Time_Zones + child of Ada.Calendar 9.6.1(2/2) +timed_entry_call 9.7.2(2) + used 9.7(2), P +Timer + in Ada.Execution_Time.Timers + +D.14.1(4/2) +timer interrupt + example 9.7.4(12) +Timer_Handler + in Ada.Execution_Time.Timers + +D.14.1(5/2) + +Timer_Resource_Error + in Ada.Execution_Time.Timers + +D.14.1(9/2) + +Timers + child of Ada.Execution_Time + +D.14.1(3/2) + +times operator 4.4(1/3), 4.5.5(1) +timing + See delay_statement 9.6(1) +Timing_Event + in Ada.Real_Time.Timing_Events + +D.15(4/2) + +Timing_Event_Handler + in Ada.Real_Time.Timing_Events + +D.15(4/2) +Timing_Events + child of Ada.Real_Time D.15(3/2) +To_Ada + in Interfaces.C B.3(22), B.3(26), + +B.3(28), B.3(32), B.3(37), B.3(39), +B.3(39.10/2), B.3(39.13/2), +B.3(39.17/2), B.3(39.19/2), +B.3(39.4/2), B.3(39.8/2) + + in Interfaces.COBOL B.4(17), B.4(19) + in Interfaces.Fortran B.5(13), B.5(14), + +B.5(16) +To_Address + in System.Address_To_Access_- +Conversions 13.7.2(3/3) + in System.Storage_Elements + +13.7.1(10/3) + +To_Basic + in Ada.Characters.Handling A.3.2(6), + +A.3.2(7) + +To_Binary + in Interfaces.COBOL B.4(45), B.4(48) +To_Bounded_String + in Ada.Strings.Bounded A.4.4(11) + +To_C + in Interfaces.C B.3(21), B.3(25), + +B.3(27), B.3(32), B.3(36), B.3(38), +B.3(39.13/2), B.3(39.16/2), +B.3(39.18/2), B.3(39.4/2), B.3(39.7/2), +B.3(39.9/2) + +To_Character + in Ada.Characters.Conversions + +A.3.4(5/2) +To_Chars_Ptr + in Interfaces.C.Strings B.3.1(8) +To_COBOL + in Interfaces.COBOL B.4(17), B.4(18) +To_Cursor + in Ada.Containers.Vectors + +A.18.2(25/2) + +To_Decimal + in Interfaces.COBOL B.4(35), B.4(40), + +To_Pointer + in System.Address_To_Access_- +Conversions 13.7.2(3/3) + +To_Range + in Ada.Strings.Maps A.4.2(24) + in Ada.Strings.Wide_Maps A.4.7(25) + in Ada.Strings.Wide_Wide_Maps + +A.4.8(25/2) + +To_Ranges + in Ada.Strings.Maps A.4.2(10) + in Ada.Strings.Wide_Maps A.4.7(10) + in Ada.Strings.Wide_Wide_Maps + +A.4.8(10/2) + +To_Sequence + in Ada.Strings.Maps A.4.2(19) + in Ada.Strings.Wide_Maps A.4.7(19) + in Ada.Strings.Wide_Wide_Maps + +A.4.8(19/2) + +B.4(44), B.4(47) + +To_Display + in Interfaces.COBOL B.4(36) +To_Domain + in Ada.Strings.Maps A.4.2(24) + in Ada.Strings.Wide_Maps A.4.7(24) + in Ada.Strings.Wide_Wide_Maps + +A.4.8(24/2) + +To_Duration + in Ada.Real_Time D.8(13) +To_Fortran + in Interfaces.Fortran B.5(13), B.5(14), + +B.5(15) +To_Holder + in Ada.Containers.Indefinite_Holders + +A.18.18(9/3) + +To_Index + in Ada.Containers.Vectors + +A.18.2(26/2) + +To_Integer + in System.Storage_Elements + +13.7.1(10/3) + +To_Set + in Ada.Containers.Hashed_Sets + +A.18.8(9/2) + + in Ada.Containers.Ordered_Sets + +A.18.9(10/2) + + in Ada.Strings.Maps A.4.2(8), +A.4.2(9), A.4.2(17), A.4.2(18) + in Ada.Strings.Wide_Maps A.4.7(8), +A.4.7(9), A.4.7(17), A.4.7(18) + in Ada.Strings.Wide_Wide_Maps + +A.4.8(8/2), A.4.8(9/2), A.4.8(17/2), +A.4.8(18/2) + +To_String + in Ada.Characters.Conversions + +A.3.4(5/2) + + in Ada.Strings.Bounded A.4.4(12) + in Ada.Strings.Unbounded A.4.5(11) +To_Time_Span + in Ada.Real_Time D.8(13) +To_Unbounded_String + in Ada.Strings.Unbounded A.4.5(9), + +A.4.5(10) + +To_ISO_646 + in Ada.Characters.Handling A.3.2(11), + +To_Upper + in Ada.Characters.Handling A.3.2(6), + +A.3.2(12) +To_Long_Binary + in Interfaces.COBOL B.4(48) +To_Lower + in Ada.Characters.Handling A.3.2(6), + +A.3.2(7) + + in Ada.Wide_Characters.Handling + +A.3.5(20/3), A.3.5(21/3) + +To_Mapping + in Ada.Strings.Maps A.4.2(23) + in Ada.Strings.Wide_Maps A.4.7(23) + in Ada.Strings.Wide_Wide_Maps + +A.4.8(23/2) + +To_Packed + in Interfaces.COBOL B.4(41) +To_Picture + in Ada.Text_IO.Editing F.3.3(6) + +A.3.2(7) + + in Ada.Wide_Characters.Handling + +A.3.5(20/3), A.3.5(21/3) + +To_Vector + in Ada.Containers.Vectors +A.18.2(13/2), A.18.2(14/2) + +To_Wide_Character + in Ada.Characters.Conversions + +A.3.4(4/2), A.3.4(5/2) + +To_Wide_String + in Ada.Characters.Conversions + +A.3.4(4/2), A.3.4(5/2) +To_Wide_Wide_Character + in Ada.Characters.Conversions + +A.3.4(4/2) + +To_Wide_Wide_String + in Ada.Characters.Conversions + +A.3.4(4/2) + +Index + +13 December 2012 914 + + Ada Reference Manual — 2012 Edition + +token + See lexical element 2.2(1) +Trailing_Nonseparate + in Interfaces.COBOL B.4(23) +Trailing_Separate + in Interfaces.COBOL B.4(23) +transfer of control 5.1(14/2) +Translate + in Ada.Strings.Bounded A.4.4(53), +A.4.4(54), A.4.4(55), A.4.4(56) + in Ada.Strings.Fixed A.4.3(18), +A.4.3(19), A.4.3(20), A.4.3(21) + in Ada.Strings.Unbounded A.4.5(48), +A.4.5(49), A.4.5(50), A.4.5(51) + +Translation_Error + in Ada.Strings A.4.1(5) +Transpose + in Ada.Numerics.Generic_Complex_- + +Arrays G.3.2(34/2) + + in Ada.Numerics.Generic_Real_Arrays + +G.3.1(17/2) + +Tree + in Ada.Containers.Multiway_Trees + +A.18.10(8/3) + +Tree_Iterator_Interfaces + in Ada.Containers.Multiway_Trees + +A.18.10(13/3) + +triggering_alternative 9.7.4(3) + used 9.7.4(2), P +triggering_statement 9.7.4(4/2) + used 9.7.4(3), P +Trim + in Ada.Strings.Bounded A.4.4(67), + +A.4.4(68), A.4.4(69) + + in Ada.Strings.Fixed A.4.3(31), +A.4.3(32), A.4.3(33), A.4.3(34) + in Ada.Strings.Unbounded A.4.5(61), +A.4.5(62), A.4.5(63), A.4.5(64) + +Trim_End + in Ada.Strings A.4.1(6) +True 3.5.3(1) +Truncation + in Ada.Strings A.4.1(6) +Truncation attribute A.5.3(42) +Tuesday + in Ada.Calendar.Formatting + +9.6.1(17/2) +two's complement + modular types 3.5.4(29) +type 3.2(1), N(41/2) + abstract 3.9.3(1.2/2) + needs finalization 7.6(9.1/2) + of a subtype 3.2(8/2) + synchronized tagged 3.9.4(6/2) + See also tag 3.9(3) + See also language-defined types +type conformance 6.3.1(15/2) + [partial] 3.4(17/2), 8.3(8), 8.3(26/2), + +10.1.4(4/3) + + required 3.11.1(5), 4.1.4(14/2), 8.6(26), +9.1(9.2/3), 9.1(9.5/3), 9.4(11.1/3), +9.4(11.4/3), 9.5.4(3/3), 12.4(5/2) + +type conversion 4.6(1/3) + access 4.6(24.11/2), 4.6(24.18/2), + +4.6(24.19/2), 4.6(47) + arbitrary order 1.1.4(18) + array 4.6(24.2/2), 4.6(36) + composite (non-array) 4.6(21/3), + +4.6(40) + + enumeration 4.6(21.1/2), 4.6(34) + numeric 4.6(24.1/2), 4.6(29) + unchecked 13.9(1) + See also qualified_expression 4.7(1) +type conversion, implicit + See implicit subtype conversion + +4.6(1/3) + +type extension 3.9(2/2), 3.9.1(1/2) +type of a discrete_range 3.6.1(4) +type of a range 3.5(4) +type parameter + See discriminant 3.7(1/2) +type profile + See profile, type conformant + +6.3.1(15/2) + +type resolution rules 8.6(20/2) + if any type in a specified class of types is + +expected 8.6(21) + + if expected type is specific 8.6(22) + if expected type is universal or class- + +wide 8.6(21) + +type tag + See tag 3.9(3) +type-related + aspect 13.1(8.1/3) + aspect 13.1(8/3) + operational item 13.1(8.1/3) + representation item 13.1(8/3) +type_conversion 4.6(2) + used 4.1(2/3), P + See also unchecked type conversion + +13.9(1) + +type_declaration 3.2.1(2) + used 3.1(3/3), P +type_definition 3.2.1(4/2) + used 3.2.1(3/3), P +Type_Invariant aspect 7.3.2(2/3) +Type_Invariant'Class aspect 7.3.2(3/3) +Type_Set + in Ada.Text_IO A.10.1(7) +types + of a profile 6.1(29) + +U + +UC_A_Acute + in Ada.Characters.Latin_1 A.3.3(23) +UC_A_Circumflex + in Ada.Characters.Latin_1 A.3.3(23) + +UC_A_Diaeresis + in Ada.Characters.Latin_1 A.3.3(23) +UC_A_Grave + in Ada.Characters.Latin_1 A.3.3(23) +UC_A_Ring + in Ada.Characters.Latin_1 A.3.3(23) +UC_A_Tilde + in Ada.Characters.Latin_1 A.3.3(23) +UC_AE_Diphthong + in Ada.Characters.Latin_1 A.3.3(23) +UC_C_Cedilla + in Ada.Characters.Latin_1 A.3.3(23) +UC_E_Acute + in Ada.Characters.Latin_1 A.3.3(23) +UC_E_Circumflex + in Ada.Characters.Latin_1 A.3.3(23) +UC_E_Diaeresis + in Ada.Characters.Latin_1 A.3.3(23) +UC_E_Grave + in Ada.Characters.Latin_1 A.3.3(23) +UC_I_Acute + in Ada.Characters.Latin_1 A.3.3(23) +UC_I_Circumflex + in Ada.Characters.Latin_1 A.3.3(23) +UC_I_Diaeresis + in Ada.Characters.Latin_1 A.3.3(23) +UC_I_Grave + in Ada.Characters.Latin_1 A.3.3(23) +UC_Icelandic_Eth + in Ada.Characters.Latin_1 A.3.3(24) +UC_Icelandic_Thorn + in Ada.Characters.Latin_1 A.3.3(24) +UC_N_Tilde + in Ada.Characters.Latin_1 A.3.3(24) +UC_O_Acute + in Ada.Characters.Latin_1 A.3.3(24) +UC_O_Circumflex + in Ada.Characters.Latin_1 A.3.3(24) +UC_O_Diaeresis + in Ada.Characters.Latin_1 A.3.3(24) +UC_O_Grave + in Ada.Characters.Latin_1 A.3.3(24) +UC_O_Oblique_Stroke + in Ada.Characters.Latin_1 A.3.3(24) +UC_O_Tilde + in Ada.Characters.Latin_1 A.3.3(24) +UC_U_Acute + in Ada.Characters.Latin_1 A.3.3(24) +UC_U_Circumflex + in Ada.Characters.Latin_1 A.3.3(24) +UC_U_Diaeresis + in Ada.Characters.Latin_1 A.3.3(24) +UC_U_Grave + in Ada.Characters.Latin_1 A.3.3(24) +UC_Y_Acute + in Ada.Characters.Latin_1 A.3.3(24) +UCHAR_MAX + in Interfaces.C B.3(6) +ultimate ancestor + of a type 3.4.1(10/2) + +915 13 December 2012 + +Index + + + + Ada Reference Manual — 2012 Edition + +unary adding operator 4.5.4(1) +unary operator 4.5(9) +unary_adding_operator 4.5(5) + used 4.4(4), P +Unbiased_Rounding attribute A.5.3(39) +Unbounded + child of Ada.Strings A.4.5(3) + in Ada.Text_IO A.10.1(5) +Unbounded_IO + child of Ada.Text_IO A.10.12(3/2) + child of Ada.Wide_Text_IO A.11(5/3) + child of Ada.Wide_Wide_Text_IO + +A.11(5/3) + +Unbounded_Priority_Queues + child of Ada.Containers A.18.30(2/3) +Unbounded_Slice + in Ada.Strings.Unbounded + +union + C B.3.3(1/3) + in Ada.Containers.Hashed_Sets +A.18.8(26/2), A.18.8(27/2) + in Ada.Containers.Ordered_Sets +A.18.9(27/2), A.18.9(28/2) + +unit consistency E.3(6) +unit matrix + complex matrix G.3.2(148/2) + real matrix G.3.1(80/2) +unit vector + complex vector G.3.2(90/2) + real vector G.3.1(48/2) +Unit_Matrix + in Ada.Numerics.Generic_Complex_- + +Arrays G.3.2(51/2) + +A.4.5(22.1/2), A.4.5(22.2/2) + +G.3.1(29/2) + + in Ada.Numerics.Generic_Real_Arrays + +Unit_Vector + in Ada.Numerics.Generic_Complex_- + +Arrays G.3.2(24/2) + + in Ada.Numerics.Generic_Real_Arrays + +G.3.1(14/2) + +universal type 3.4.1(6/2) +universal_access + [partial] 3.4.1(6/2), 4.2(8/2) +universal_fixed + [partial] 3.4.1(6/2), 3.5.6(4) +universal_integer + [partial] 3.4.1(6/2), 3.5.4(14), + +3.5.4(30), 4.2(8/2) + +universal_real + [partial] 3.4.1(6/2), 3.5.6(4), 4.2(8/2) +unknown discriminants 3.7(26) +unknown_discriminant_part 3.7(3) + used 3.7(2/2), P +Unknown_Zone_Error + in Ada.Calendar.Time_Zones + +9.6.1(5/2) + +unmarshalling E.4(9) +unpolluted 13.13.1(2) +unsigned + in Interfaces.C B.3(9) + in Interfaces.COBOL B.4(23) +unsigned type + See modular type 3.5.4(1) +unsigned_char + in Interfaces.C B.3(10) +unsigned_long + in Interfaces.C B.3(9) +unsigned_short + in Interfaces.C B.3(9) +unspecified 1.1.3(18) + +Unbounded_String + in Ada.Strings.Unbounded A.4.5(4/2) +Unbounded_Synchronized_Queues + child of Ada.Containers A.18.28(2/3) +unchecked storage deallocation + +13.11.2(1) + +unchecked type conversion 13.9(1) +unchecked union object B.3.3(6/3) +unchecked union subtype B.3.3(6/3) +unchecked union type B.3.3(6/3) +Unchecked_Access attribute 13.10(3), + +H.4(18) + + See also Access attribute 3.10.2(24/1) +Unchecked_Conversion + child of Ada 13.9(3/3) +Unchecked_Deallocation + child of Ada 13.11.2(3/3) +Unchecked_Union aspect B.3.3(3.2/3) +Unchecked_Union pragma J.15.6(2/3), + +L(37.2/3) + +unconstrained 3.2(9) + object 3.3.1(9/2) + object 6.4.1(16) + subtype 3.2(9), 3.4(6), 3.5(7), +3.5.1(10), 3.5.4(9), 3.5.4(10), +3.5.7(11), 3.5.9(13), 3.5.9(16), +3.6(15), 3.6(16), 3.7(26), 3.9(15) + + subtype 3.10(14/3) + subtype K.2(33) +unconstrained_array_definition 3.6(3) + used 3.6(2), P +undefined result 11.6(5) +underline 2.1(15/3) + used 2.4.1(3), 2.4.2(4), P +Uniformly_Distributed subtype of Float + in Ada.Numerics.Float_Random + +A.5.2(8) + +uninitialized allocator 4.8(4) +uninitialized variables 13.9.1(2) + [partial] 3.3.1(21/3) + + [partial] 2.1(5/3), 3.9(4/2), 3.9(12.5/3), +4.5.2(13), 4.5.2(24.2/1), 4.5.5(21), +6.1.1(34/3), 6.1.1(35/3), 6.2(11/3), +7.2(5/3), 7.6(17.4/3), 9.8(14), +9.10(1/3), 10.2(26), 11.1(6), +11.4.1(10.1/3), 11.5(27/2), 13.1(18), +13.7.2(5/2), 13.9.1(7), 13.11(20), +13.11(21.6/3), 13.13.2(36/2), A.1(1/3), +A.5.1(34), A.5.2(28), A.5.2(34), +A.5.3(41.3/2), A.7(6), A.10(8), +A.10.7(8/3), A.10.7(12/3), +A.10.7(17.3/2), A.10.7(19), A.14(1), +A.18.2(231/3), A.18.2(252/2), +A.18.2(83/2), A.18.3(145/3), +A.18.3(157/2), A.18.3(55/2), +A.18.4(3/2), A.18.4(80/2), +A.18.5(43/2), A.18.5(44/2), +A.18.5(45/2), A.18.5(46/2), +A.18.6(56/3), A.18.6(57/2), +A.18.7(3/2), A.18.7(101/2), +A.18.7(87/2), A.18.7(88/2), +A.18.8(65/2), A.18.8(66.1/3), +A.18.8(66/2), A.18.8(67/2), +A.18.8(68/2), A.18.8(86/2), +A.18.8(87/2), A.18.9(114/2), +A.18.9(79.1/3), A.18.9(79/3), +A.18.9(80/2), A.18.10(227/3), +A.18.10(72/3), A.18.26(5/3), +A.18.26(9.4/3), A.18.26(9/3), +D.2.2(7.1/2), D.8(19), E.3(5/1), +G.1.1(40), G.1.2(33), G.1.2(48), +H(4.1), H.2(1), K.2(136.4/2) +Unsuppress pragma 11.5(4.1/2), + +L(37.3/2) + +update + the value of an object 3.3(14) + in Interfaces.C.Strings B.3.1(18), + +B.3.1(19) +Update_Element + in Ada.Containers.Doubly_Linked_- + +Lists A.18.3(17/2) + + in Ada.Containers.Hashed_Maps + +A.18.5(17/2) + + in Ada.Containers.Indefinite_Holders + +A.18.18(15/3) + + in Ada.Containers.Multiway_Trees + +A.18.10(27/3) + + in Ada.Containers.Ordered_Maps + +A.18.6(16/2) + + in Ada.Containers.Vectors +A.18.2(33/2), A.18.2(34/2) +Update_Element_Preserving_Key + in Ada.Containers.Hashed_Sets + +A.18.8(58/2) + + in Ada.Containers.Ordered_Sets + +A.18.9(73/2) + +Update_Error + in Interfaces.C.Strings B.3.1(20) +upper bound + of a range 3.5(4) + +Index + +13 December 2012 916 + + Ada Reference Manual — 2012 Edition + +upper-case letter + a category of Character A.3.2(26) +Upper_Case_Map + in Ada.Strings.Maps.Constants + +A.4.6(5) + +Value + in Ada.Calendar.Formatting +9.6.1(36/2), 9.6.1(38/2) + + in Ada.Environment_Variables + +A.17(4.1/3), A.17(4/2) + +visible 8.3(2), 8.3(14) + aspect_specification 8.3(23.1/3) + attribute_definition_clause 8.3(23.1/3) + within a pragma in a context_clause + +10.1.6(3) + +Upper_Set + in Ada.Strings.Maps.Constants + + in Ada.Numerics.Discrete_Random + + within a pragma that appears at the place + +A.5.2(26) + +of a compilation unit 10.1.6(5) + +A.4.6(4) + + in Ada.Numerics.Float_Random + + within a use_clause in a context_clause + +US + in Ada.Characters.Latin_1 A.3.3(6) +usage name 3.1(10) +use-visible 8.3(4), 8.4(9) +use_clause 8.4(2) + used 3.11(4/1), 10.1.2(3), 12.1(5), P +Use_Error + in Ada.Direct_IO A.8.4(18) + in Ada.Directories A.16(43/2) + in Ada.IO_Exceptions A.13(4) + in Ada.Sequential_IO A.8.1(15) + in Ada.Streams.Stream_IO A.12.1(26) + in Ada.Text_IO A.10.1(85) +use_package_clause 8.4(3) + used 8.4(2), P +use_type_clause 8.4(4/3) + used 8.4(2), P +user-defined assignment 7.6(1) +user-defined heap management 13.11(1) +user-defined operator 6.6(1) +user-defined storage management + +13.11(1) + +UTC_Time_Offset + in Ada.Calendar.Time_Zones + +9.6.1(6/2) + +UTF-16 A.4.11(46/3) +UTF-8 A.4.11(46/3) +UTF_16_Wide_String subtype of + +Wide_String + +A.4.11(7/3) + +UTF_8_String subtype of String + in Ada.Strings.UTF_Encoding + +A.4.11(6/3) +UTF_Encoding + child of Ada.Strings A.4.11(3/3) +UTF_String subtype of String + in Ada.Strings.UTF_Encoding + +A.4.11(5/3) + +V + +Val attribute 3.5.5(5) +Valid + in Ada.Text_IO.Editing F.3.3(5), + +F.3.3(12) + + in Interfaces.COBOL B.4(33), B.4(38), + +B.4(43) + +Valid attribute 13.9.2(3/3), H(6) + +A.5.2(14) + +10.1.6(3) + + in Ada.Strings.Maps A.4.2(21) + in Ada.Strings.Wide_Maps A.4.7(21) + in Ada.Strings.Wide_Wide_Maps + +A.4.8(21/2) + + in Ada.Task_Attributes C.7.2(4) + in Interfaces.C.Pointers B.3.2(6), + +B.3.2(7) + + in Interfaces.C.Strings B.3.1(13), +B.3.1(14), B.3.1(15), B.3.1(16) + +Value attribute 3.5(52) +value conversion 4.6(5/2) +values + belonging to a subtype 3.2(8/2) +variable 3.3(13/3) +variable indexing 4.1.6(16/3) +variable object 3.3(13/3) +variable view 3.3(13/3) +Variable_Indexing aspect 4.1.6(3/3) +variant 3.8.1(3) + used 3.8.1(2), P + See also tagged type 3.9(1) +variant_part 3.8.1(2) + used 3.8(4), P +Vector + in Ada.Containers.Vectors A.18.2(8/3) +vector container A.18.2(1/2) +Vector_Iterator_Interfaces + in Ada.Containers.Vectors + +Vectors + child of Ada.Containers A.18.2(6/3) +version + of a compilation unit E.3(5/1) +Version attribute E.3(3) +vertical line 2.1(15/3) +Vertical_Line + in Ada.Characters.Latin_1 A.3.3(14) +view 3.1(7), N(42/2) + of a subtype (implied) 3.1(7.1/3) + of a type (implied) 3.1(7.1/3) + of an object (implied) 3.1(7.1/3) +view conversion 4.6(5/2) +virtual function + See dispatching subprogram 3.9.2(1/2) +Virtual_Length + in Interfaces.C.Pointers B.3.2(13) +visibility + direct 8.3(2), 8.3(21) + immediate 8.3(4), 8.3(21) + use clause 8.3(4), 8.4(9) +visibility rules 8.3(1) + + within a with_clause 10.1.6(2/2) + within the parent_unit_name of a library + +unit 10.1.6(2/2) + + within the parent_unit_name of a + +subunit 10.1.6(4) + +visible part 8.2(5) + of a formal package 12.7(10/2) + of a generic unit 8.2(8) + of a package (other than a generic +formal package) 7.1(6/2) + of a protected unit 9.4(11/2) + of a task unit 9.1(9) + of a view of a callable entity 8.2(6) + of a view of a composite type 8.2(7) +volatile C.6(8/3) +Volatile aspect C.6(6.4/3) +Volatile pragma J.15.8(3/3), L(38.1/3) +Volatile_Components aspect C.6(6.7/3) +Volatile_Components pragma +J.15.8(6/3), L(39.1/3) + +VT + in Ada.Characters.Latin_1 A.3.3(5) +VTS + in Ada.Characters.Latin_1 A.3.3(17) + +W + +Wait_For_Release + in Ada.Synchronous_Barriers + +D.10.1(6/3) + +wchar_array + in Interfaces.C B.3(33/3) +wchar_t + in Interfaces.C B.3(30/1) +Wednesday + in Ada.Calendar.Formatting + +9.6.1(17/2) + +well-formed picture String + for edited output F.3.1(1/3) +Wide_Bounded + child of Ada.Strings A.4.7(1/3) +Wide_Character 3.5.2(3/3) + in Standard A.1(36.1/3) +Wide_Character_Mapping + in Ada.Strings.Wide_Maps A.4.7(20/2) +Wide_Character_Mapping_Function + in Ada.Strings.Wide_Maps A.4.7(26) +Wide_Character_Range + in Ada.Strings.Wide_Maps A.4.7(6) +Wide_Character_Ranges + in Ada.Strings.Wide_Maps A.4.7(7) + + in Ada.Strings.UTF_Encoding + +A.18.2(11.2/3) + +917 13 December 2012 + +Index + + + + + + Ada Reference Manual — 2012 Edition + +Wide_Character_Sequence subtype of + +Wide_String + + in Ada.Strings.Wide_Maps A.4.7(16) +Wide_Character_Set + in Ada.Strings.Wide_Maps A.4.7(4/2) + in Ada.Strings.Wide_Maps.Wide_- + +Wide_Wide_Bounded + child of Ada.Strings A.4.8(1/3) +Wide_Wide_Character 3.5.2(4/3) + in Standard A.1(36.2/3) +Wide_Wide_Character_Mapping + in Ada.Strings.Wide_Wide_Maps + +Constants A.4.8(48/2) + +A.4.8(20/2) + +Wide_Characters + child of Ada A.3.1(4/2) +Wide_Constants + child of Ada.Strings.Wide_Maps + +A.4.7(1/3), A.4.8(28/2) +Wide_Equal_Case_Insensitive + child of Ada.Strings A.4.7(1/3) + child of Ada.Strings.Wide_Bounded + +A.4.7(1/3) + +Wide_Wide_Character_Mapping_Functio + +n + + in Ada.Strings.Wide_Wide_Maps + +A.4.8(26/2) + +Wide_Wide_Character_Range + in Ada.Strings.Wide_Wide_Maps + +A.4.8(6/2) + +Wide_Wide_Character_Ranges + in Ada.Strings.Wide_Wide_Maps + + child of Ada.Strings.Wide_Fixed + +A.4.8(7/2) + +A.4.7(1/3) + +Wide_Wide_Character_Sequence subtype + + child of Ada.Strings.Wide_Unbounded + +of Wide_Wide_String + +A.4.7(1/3) + + in Ada.Strings.Wide_Wide_Maps + +Wide_Exception_Name + in Ada.Exceptions 11.4.1(2/2), + +11.4.1(5/2) + +Wide_Expanded_Name + in Ada.Tags 3.9(7/2) +Wide_Fixed + child of Ada.Strings A.4.7(1/3) +Wide_Hash + child of Ada.Strings A.4.7(1/3) + child of Ada.Strings.Wide_Bounded + +A.4.7(1/3) + + child of Ada.Strings.Wide_Fixed + +A.4.7(1/3) + +A.4.8(16/2) + +Wide_Wide_Character_Set + in Ada.Strings.Wide_Wide_Maps + +A.4.8(4/2) + +Wide_Wide_Characters + child of Ada A.3.1(6/2) +Wide_Wide_Constants + child of Ada.Strings.Wide_Wide_Maps + +A.4.8(1/3) + +Wide_Wide_Equal_Case_Insensitive + child of Ada.Strings A.4.8(1/3) + child of Ada.Strings.Wide_Wide_- + +Bounded A.4.8(1/3) + +Wide_Wide_Image attribute 3.5(27.1/2) +Wide_Wide_Maps + child of Ada.Strings A.4.8(3/2) +Wide_Wide_Space + in Ada.Strings A.4.1(4/2) +Wide_Wide_String + in Standard A.1(42.1/3) +Wide_Wide_Strings + child of Ada.Strings.UTF_Encoding + +A.4.11(38/3) +Wide_Wide_Text_IO + child of Ada A.11(3/2) +Wide_Wide_Unbounded + child of Ada.Strings A.4.8(1/3) +Wide_Wide_Value attribute 3.5(39.1/2) +Wide_Wide_Width attribute 3.5(37.1/2) +Wide_Width attribute 3.5(38) +Width attribute 3.5(39) +with_clause 10.1.2(4/2) + mentioned in 10.1.2(6/2) + named in 10.1.2(6/2) + used 10.1.2(3), P +within + immediately 8.1(13) +word 13.3(8) +Word_Size + in System 13.7(13) +Write + in Ada.Direct_IO A.8.4(13) + in Ada.Sequential_IO A.8.1(12) + in Ada.Storage_IO A.9(7) + in Ada.Streams 13.13.1(6) + in Ada.Streams.Stream_IO A.12.1(18), + + child of Ada.Strings.Wide_Unbounded + + child of Ada.Strings.Wide_Wide_Fixed + +A.12.1(19) + +A.4.7(1/3) + +A.4.8(1/3) + +Wide_Hash_Case_Insensitive + child of Ada.Strings A.4.7(1/3) + child of Ada.Strings.Wide_Bounded + +A.4.7(1/3) + + child of Ada.Strings.Wide_Wide_- + +Unbounded A.4.8(1/3) +Wide_Wide_Exception_Name + in Ada.Exceptions 11.4.1(2/2), + + child of Ada.Strings.Wide_Fixed + +11.4.1(5/2) + +A.4.7(1/3) + + child of Ada.Strings.Wide_Unbounded + +A.4.7(1/3) + +Wide_Image attribute 3.5(28) +Wide_Maps + child of Ada.Strings A.4.7(3) +wide_nul + in Interfaces.C B.3(31/1) +Wide_Space + in Ada.Strings A.4.1(4/2) +Wide_String + in Standard A.1(41/3) +Wide_Strings + child of Ada.Strings.UTF_Encoding + +A.4.11(30/3) + +Wide_Text_IO + child of Ada A.11(2/2) +Wide_Unbounded + child of Ada.Strings A.4.7(1/3) +Wide_Value attribute 3.5(40) + +Wide_Wide_Expanded_Name + in Ada.Tags 3.9(7/2) +Wide_Wide_Fixed + child of Ada.Strings A.4.8(1/3) +Wide_Wide_Hash + child of Ada.Strings A.4.8(1/3) + child of Ada.Strings.Wide_Wide_- + +Bounded A.4.8(1/3) + +A.4.8(1/3) + + child of Ada.Strings.Wide_Wide_- + +Unbounded A.4.8(1/3) + +Wide_Wide_Hash_Case_Insensitive + child of Ada.Strings A.4.8(1/3) + child of Ada.Strings.Wide_Wide_- + +Bounded A.4.8(1/3) + + in System.RPC E.5(8) +Write aspect 13.13.2(38/3) +Write attribute 13.13.2(3), 13.13.2(11) +Write clause 13.3(7/2), 13.13.2(38/3) + +X + +xor operator 4.4(1/3), 4.5.1(2) + +Y + +Year + in Ada.Calendar 9.6(13) + in Ada.Calendar.Formatting + +Year_Number subtype of Integer + in Ada.Calendar 9.6(11/2) +Yen_Sign + in Ada.Characters.Latin_1 A.3.3(21/3) +Yield + in Ada.Dispatching D.2.1(1.3/3) +Yield_To_Higher + in Ada.Dispatching.Non_Preemptive + + child of Ada.Strings.Wide_Wide_Fixed + +A.4.8(1/3) + +D.2.4(2.2/3) + + child of Ada.Strings.Wide_Wide_- + +Unbounded A.4.8(1/3) + + child of Ada.Strings.Wide_Wide_Fixed + +9.6.1(21/2) + +Index + +13 December 2012 918 + + + + + + Yield_To_Same_Or_Higher + in Ada.Dispatching.Non_Preemptive + +D.2.4(2.2/3) + +Ada Reference Manual — 2012 Edition + +919 13 December 2012 + +Index + + + \ No newline at end of file