utils.py

import re
import torch
from cleantext import clean
from itertools import chain

class MosesPunctNormalizer:
    """
    This is a Python port of the Moses punctuation normalizer from
    https://github.com/moses-smt/mosesdecoder/blob/master/scripts/tokenizer/normalize-punctuation.perl
    """

    EXTRA_WHITESPACE = [  # lines 21 - 30
        (r"\r", r""),
        (r"\(", r" ("),
        (r"\)", r") "),
        (r" +", r" "),
        (r"\) ([.!:?;,])", r")\g<1>"),
        (r"\( ", r"("),
        (r" \)", r")"),
        (r"(\d) %", r"\g<1>%"),
        (r" :", r":"),
        (r" ;", r";"),
    ]

    NORMALIZE_UNICODE_IF_NOT_PENN = [(r"`", r"'"), (r"''", r' " ')]  # lines 33 - 34

    NORMALIZE_UNICODE = [  # lines 37 - 50
        ("„", r'"'),
        ("“", r'"'),
        ("”", r'"'),
        ("–", r"-"),
        ("—", r" - "),
        (r" +", r" "),
        ("´", r"'"),
        ("([a-zA-Z])‘([a-zA-Z])", r"\g<1>'\g<2>"),
        ("([a-zA-Z])’([a-zA-Z])", r"\g<1>'\g<2>"),
        ("‘", r"'"),
        ("‚", r"'"),
        ("’", r"'"),
        (r"''", r'"'),
        ("´´", r'"'),
        ("…", r"..."),
    ]

    FRENCH_QUOTES = [  # lines 52 - 57
        ("\u00A0«\u00A0", r'"'),
        ("«\u00A0", r'"'),
        ("«", r'"'),
        ("\u00A0»\u00A0", r'"'),
        ("\u00A0»", r'"'),
        ("»", r'"'),
    ]

    HANDLE_PSEUDO_SPACES = [  # lines 59 - 67
        ("\u00A0%", r"%"),
        ("nº\u00A0", "nº "),
        ("\u00A0:", r":"),
        ("\u00A0ºC", " ºC"),
        ("\u00A0cm", r" cm"),
        ("\u00A0\\?", "?"),
        ("\u00A0\\!", "!"),
        ("\u00A0;", r";"),
        (",\u00A0", r", "),
        (r" +", r" "),
    ]

    EN_QUOTATION_FOLLOWED_BY_COMMA = [(r'"([,.]+)', r'\g<1>"')]

    DE_ES_FR_QUOTATION_FOLLOWED_BY_COMMA = [
        (r',"', r'",'),
        (r'(\.+)"(\s*[^<])', r'"\g<1>\g<2>'),  # don't fix period at end of sentence
    ]

    DE_ES_CZ_CS_FR = [
        ("(\\d)\u00A0(\\d)", r"\g<1>,\g<2>"),
    ]

    OTHER = [
        ("(\\d)\u00A0(\\d)", r"\g<1>.\g<2>"),
    ]

    # Regex substitutions from replace-unicode-punctuation.perl
    # https://github.com/moses-smt/mosesdecoder/blob/master/scripts/tokenizer/replace-unicode-punctuation.perl
    REPLACE_UNICODE_PUNCTUATION = [
        ("，", ","),
        (r"。\s*", ". "),
        ("、", ","),
        ("”", '"'),
        ("“", '"'),
        ("∶", ":"),
        ("：", ":"),
        ("？", "?"),
        ("《", '"'),
        ("》", '"'),
        ("）", ")"),
        ("！", "!"),
        ("（", "("),
        ("；", ";"),
        ("」", '"'),
        ("「", '"'),
        ("０", "0"),
        ("１", "1"),
        ("２", "2"),
        ("３", "3"),
        ("４", "4"),
        ("５", "5"),
        ("６", "6"),
        ("７", "7"),
        ("８", "8"),
        ("９", "9"),
        (r"．\s*", ". "),
        ("～", "~"),
        ("’", "'"),
        ("…", "..."),
        ("━", "-"),
        ("〈", "<"),
        ("〉", ">"),
        ("【", "["),
        ("】", "]"),
        ("％", "%"),
    ]

    def __init__(
        self,
        lang="en",
        penn=True,
        norm_quote_commas=True,
        norm_numbers=True,
        pre_replace_unicode_punct=False,
        post_remove_control_chars=False,
    ):
        """
        :param language: The two-letter language code.
        :type lang: str
        :param penn: Normalize Penn Treebank style quotations.
        :type penn: bool
        :param norm_quote_commas: Normalize quotations and commas
        :type norm_quote_commas: bool
        :param norm_numbers: Normalize numbers
        :type norm_numbers: bool
        """
        self.substitutions = [
            self.EXTRA_WHITESPACE,
            self.NORMALIZE_UNICODE,
            self.FRENCH_QUOTES,
            self.HANDLE_PSEUDO_SPACES,
        ]

        if penn:  # Adds the penn substitutions after extra_whitespace regexes.
            self.substitutions.insert(1, self.NORMALIZE_UNICODE_IF_NOT_PENN)

        if norm_quote_commas:
            if lang == "en":
                self.substitutions.append(self.EN_QUOTATION_FOLLOWED_BY_COMMA)
            elif lang in ["de", "es", "fr"]:
                self.substitutions.append(self.DE_ES_FR_QUOTATION_FOLLOWED_BY_COMMA)

        if norm_numbers:
            if lang in ["de", "es", "cz", "cs", "fr"]:
                self.substitutions.append(self.DE_ES_CZ_CS_FR)
            else:
                self.substitutions.append(self.OTHER)

        self.substitutions = list(chain(*self.substitutions))

        self.pre_replace_unicode_punct = pre_replace_unicode_punct
        self.post_remove_control_chars = post_remove_control_chars

    def normalize(self, text):
        """
        Returns a string with normalized punctuation.
        """
        # Optionally, replace unicode puncts BEFORE normalization.
        if self.pre_replace_unicode_punct:
            text = self.replace_unicode_punct(text)

        # Actual normalization.
        for regexp, substitution in self.substitutions:
            # print(regexp, substitution)
            text = re.sub(regexp, substitution, str(text))
            # print(text)

        # Optionally, replace unicode puncts BEFORE normalization.
        if self.post_remove_control_chars:
            text = self.remove_control_chars(text)

        return text.strip()

    def replace_unicode_punct(self, text):
        for regexp, substitution in self.REPLACE_UNICODE_PUNCTUATION:
            text = re.sub(regexp, substitution, str(text))
        return text

    def remove_control_chars(self, text):
        return regex.sub(r"\p{C}", "", text)

def _tokenization_norm(text):
    text = text.replace(
        ' ,', ',').replace(
        ' .', '.').replace(
        ' ?', '?').replace(
        ' !', '!').replace(
        ' ;', ';').replace(
        ' \'', '\'').replace(
        ' ’ ', '\'').replace(
        ' :', ':').replace(
        '<newline>', '\n').replace(
        '`` ', '"').replace(
        ' \'\'', '"').replace(
        '\'\'', '"').replace(
        '.. ', '... ').replace(
        ' )', ')').replace(
        '( ', '(').replace(
        ' n\'t', 'n\'t').replace(
        ' i ', ' I ').replace(
        ' i\'', ' I\'').replace(
        '\\\'', '\'').replace(
        '\n ', '\n').strip()
    return text


def _clean_text(text):
    # remove PLM special tokens
    plm_special_tokens = r'(\<pad\>)|(\<s\>)|(\<\/s\>)|(\<unk\>)|(\<\|endoftext\|\>)'
    text = re.sub(plm_special_tokens, "", text)

    # normalize puncuations
    moses_norm = MosesPunctNormalizer()
    text = moses_norm.normalize(text)
    
    # normalize tokenization
    text = _tokenization_norm(text)
    
    # remove specific text patterns, e.g,, url, email and phone number
    text = clean(text,
        fix_unicode=True,               # fix various unicode errors
        to_ascii=True,                  # transliterate to closest ASCII representation
        lower=False,                     # lowercase text
        no_line_breaks=True,           # fully strip line breaks as opposed to only normalizing them
        no_urls=True,                  # replace all URLs with a special token
        no_emails=True,                # replace all email addresses with a special token
        no_phone_numbers=True,         # replace all phone numbers with a special token
        no_numbers=False,               # replace all numbers with a special token
        no_digits=False,                # replace all digits with a special token
        no_currency_symbols=False,      # replace all currency symbols with a special token
        no_punct=False,                 # remove punctuations
        replace_with_punct="",          # instead of removing punctuations you may replace them
        replace_with_url="",
        replace_with_email="",
        replace_with_phone_number="",
        replace_with_number="<NUMBER>",
        replace_with_digit="<DIGIT>",
        replace_with_currency_symbol="<CUR>",
        lang="en"                       # set to 'de' for German special handling
    )
    
    # keep common puncts only
    punct_pattern = r'[^ A-Za-z0-9.?!,:;\-\[\]\{\}\(\)\'\"]'
    text = re.sub(punct_pattern, '', text)
    # remove specific patterns
    spe_pattern = r'[-\[\]\{\}\(\)\'\"]{2,}'
    text = re.sub(spe_pattern, '', text)
    # remove redundate spaces
    text = " ".join(text.split())
    return text

def _rm_line_break(text):
    text = text.replace("\n","\\n")
    text = re.sub(r'(?:\\n)*\\n', r'\\n', text)
    text = re.sub(r'^.{0,3}\\n', '', text)
    text = text.replace("\\n"," ")
    return text

def preprocess(text):
    text = _rm_line_break(text)
    text = _clean_text(text)
    return text