| # Copyright 2018 Google LLC | |
| # | |
| # Licensed under the Apache License, Version 2.0 (the "License"); | |
| # you may not use this file except in compliance with the License. | |
| # You may obtain a copy of the License at | |
| # | |
| # https://www.apache.org/licenses/LICENSE-2.0 | |
| # | |
| # Unless required by applicable law or agreed to in writing, software | |
| # distributed under the License is distributed on an "AS IS" BASIS, | |
| # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | |
| # See the License for the specific language governing permissions and | |
| # limitations under the License. | |
| import functools | |
| def has_upb(): | |
| try: | |
| from google._upb import _message # pylint: disable=unused-import | |
| has_upb = True | |
| except ImportError: | |
| has_upb = False | |
| return has_upb | |
| def cached_property(fx): | |
| """Make the callable into a cached property. | |
| Similar to @property, but the function will only be called once per | |
| object. | |
| Args: | |
| fx (Callable[]): The property function. | |
| Returns: | |
| Callable[]: The wrapped function. | |
| """ | |
| def inner(self): | |
| # Sanity check: If there is no cache at all, create an empty cache. | |
| if not hasattr(self, "_cached_values"): | |
| object.__setattr__(self, "_cached_values", {}) | |
| # If and only if the function's result is not in the cache, | |
| # run the function. | |
| if fx.__name__ not in self._cached_values: | |
| self._cached_values[fx.__name__] = fx(self) | |
| # Return the value from cache. | |
| return self._cached_values[fx.__name__] | |
| return property(inner) | |
| __all__ = ("cached_property",) | |