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+#!/usr/bin/python
+# -*- coding: utf-8 -*-
+#
+# This script builds unaccent.rules on standard output when given the
+# contents of UnicodeData.txt [1] and Latin-ASCII.xml [2] given as
+# arguments. Optionally includes ligature expansion and Unicode CLDR
+# Latin-ASCII transliterator, enabled by default, this can be disabled
+# with "--no-ligatures-expansion" command line option.
+#
+# The approach is to use the Unicode decomposition data to identify
+# precomposed codepoints that are equivalent to a ligature of several
+# letters, or a base letter with any number of diacritical marks.
+#
+# This approach handles most letters with diacritical marks and some
+# ligatures. However, several characters (notably a majority of
+# ligatures) don't have decomposition. To handle all these cases, one can
+# use a standard Unicode transliterator available in Common Locale Data
+# Repository (CLDR): Latin-ASCII. This transliterator associates Unicode
+# characters to ASCII-range equivalent. Unless "--no-ligatures-expansion"
+# option is enabled, the XML file of this transliterator [2] -- given as a
+# command line argument -- will be parsed and used.
+#
+# Ideally you should use the latest release for each data set. This
+# script is compatible with at least CLDR release 29.
+#
+# [1] https://www.unicode.org/Public/${UNICODE_VERSION}/ucd/UnicodeData.txt
+# [2] https://raw.githubusercontent.com/unicode-org/cldr/${TAG}/common/transforms/Latin-ASCII.xml
+
+import argparse
+import codecs
+import re
+import sys
+import xml.etree.ElementTree as ET
+
+sys.stdout = codecs.getwriter('utf8')(sys.stdout.buffer)
+
+# The ranges of Unicode characters that we consider to be "plain letters".
+# For now we are being conservative by including only Latin and Greek. This
+# could be extended in future based on feedback from people with relevant
+# language knowledge.
+PLAIN_LETTER_RANGES = ((ord('a'), ord('z')), # Latin lower case
+ (ord('A'), ord('Z')), # Latin upper case
+ (0x03b1, 0x03c9), # GREEK SMALL LETTER ALPHA, GREEK SMALL LETTER OMEGA
+ (0x0391, 0x03a9)) # GREEK CAPITAL LETTER ALPHA, GREEK CAPITAL LETTER OMEGA
+
+# Combining marks follow a "base" character, and result in a composite
+# character. Example: "U&'A\0300'"produces "À".There are three types of
+# combining marks: enclosing (Me), non-spacing combining (Mn), spacing
+# combining (Mc). We identify the ranges of marks we feel safe removing.
+# References:
+# https://en.wikipedia.org/wiki/Combining_character
+# https://www.unicode.org/charts/PDF/U0300.pdf
+# https://www.unicode.org/charts/PDF/U20D0.pdf
+COMBINING_MARK_RANGES = ((0x0300, 0x0362), # Mn: Accents, IPA
+ (0x20dd, 0x20E0), # Me: Symbols
+ (0x20e2, 0x20e4),) # Me: Screen, keycap, triangle
+
+
+def print_record(codepoint, letter):
+ if letter:
+ output = chr(codepoint) + "\t" + letter
+ else:
+ output = chr(codepoint)
+
+ print(output)
+
+
+class Codepoint:
+ def __init__(self, id, general_category, combining_ids):
+ self.id = id
+ self.general_category = general_category
+ self.combining_ids = combining_ids
+
+
+def is_mark_to_remove(codepoint):
+ """Return true if this is a combining mark to remove."""
+ if not is_mark(codepoint):
+ return False
+
+ for begin, end in COMBINING_MARK_RANGES:
+ if codepoint.id >= begin and codepoint.id <= end:
+ return True
+ return False
+
+
+def is_plain_letter(codepoint):
+ """Return true if codepoint represents a "plain letter"."""
+ for begin, end in PLAIN_LETTER_RANGES:
+ if codepoint.id >= begin and codepoint.id <= end:
+ return True
+ return False
+
+
+def is_mark(codepoint):
+ """Returns true for diacritical marks (combining codepoints)."""
+ return codepoint.general_category in ("Mn", "Me", "Mc")
+
+
+def is_letter_with_marks(codepoint, table):
+ """Returns true for letters combined with one or more marks."""
+ # See https://www.unicode.org/reports/tr44/tr44-14.html#General_Category_Values
+
+ # Letter may have no combining characters, in which case it has
+ # no marks.
+ if len(codepoint.combining_ids) == 1:
+ return False
+
+ # A letter without diacritical marks has none of them.
+ if any(is_mark(table[i]) for i in codepoint.combining_ids[1:]) is False:
+ return False
+
+ # Check if the base letter of this letter has marks.
+ codepoint_base = codepoint.combining_ids[0]
+ if is_plain_letter(table[codepoint_base]) is False and \
+ is_letter_with_marks(table[codepoint_base], table) is False:
+ return False
+
+ return True
+
+
+def is_letter(codepoint, table):
+ """Return true for letter with or without diacritical marks."""
+ return is_plain_letter(codepoint) or is_letter_with_marks(codepoint, table)
+
+
+def get_plain_letter(codepoint, table):
+ """Return the base codepoint without marks. If this codepoint has more
+ than one combining character, do a recursive lookup on the table to
+ find out its plain base letter."""
+ if is_letter_with_marks(codepoint, table):
+ if len(table[codepoint.combining_ids[0]].combining_ids) > 1:
+ return get_plain_letter(table[codepoint.combining_ids[0]], table)
+ elif is_plain_letter(table[codepoint.combining_ids[0]]):
+ return table[codepoint.combining_ids[0]]
+
+ # Should not come here
+ assert(False)
+ elif is_plain_letter(codepoint):
+ return codepoint
+
+ # Should not come here
+ assert(False)
+
+
+def is_ligature(codepoint, table):
+ """Return true for letters combined with letters."""
+ return all(is_letter(table[i], table) for i in codepoint.combining_ids)
+
+
+def get_plain_letters(codepoint, table):
+ """Return a list of plain letters from a ligature."""
+ assert(is_ligature(codepoint, table))
+ return [get_plain_letter(table[id], table) for id in codepoint.combining_ids]
+
+
+def parse_cldr_latin_ascii_transliterator(latinAsciiFilePath):
+ """Parse the XML file and return a set of tuples (src, trg), where "src"
+ is the original character and "trg" the substitute."""
+ charactersSet = set()
+
+ # RegEx to parse rules
+ rulePattern = re.compile(r'^(?:(.)|(\\u[0-9a-fA-F]{4})) \u2192 (?:\'(.+)\'|(.+)) ;')
+
+ # construct tree from XML
+ transliterationTree = ET.parse(latinAsciiFilePath)
+ transliterationTreeRoot = transliterationTree.getroot()
+
+ # Fetch all the transliteration rules. Since release 29 of Latin-ASCII.xml
+ # all the transliteration rules are located in a single tRule block with
+ # all rules separated into separate lines.
+ blockRules = transliterationTreeRoot.findall("./transforms/transform/tRule")
+ assert(len(blockRules) == 1)
+
+ # Split the block of rules into one element per line.
+ rules = blockRules[0].text.splitlines()
+
+ # And finish the processing of each individual rule.
+ for rule in rules:
+ matches = rulePattern.search(rule)
+
+ # The regular expression capture four groups corresponding
+ # to the characters.
+ #
+ # Group 1: plain "src" char. Empty if group 2 is not.
+ # Group 2: unicode-escaped "src" char (e.g. "\u0110"). Empty if group 1 is not.
+ #
+ # Group 3: plain "trg" char. Empty if group 4 is not.
+ # Group 4: plain "trg" char between quotes. Empty if group 3 is not.
+ if matches is not None:
+ src = matches.group(1) if matches.group(1) is not None else bytes(matches.group(2), 'UTF-8').decode('unicode-escape')
+ trg = matches.group(3) if matches.group(3) is not None else matches.group(4)
+
+ # "'" and """ are escaped
+ trg = trg.replace("\\'", "'").replace('\\"', '"')
+
+ # the parser of unaccent only accepts non-whitespace characters
+ # for "src" and "trg" (see unaccent.c)
+ if not src.isspace() and not trg.isspace():
+ charactersSet.add((ord(src), trg))
+
+ return charactersSet
+
+
+def special_cases():
+ """Returns the special cases which are not handled by other methods"""
+ charactersSet = set()
+
+ # Cyrillic
+ charactersSet.add((0x0401, "\u0415")) # CYRILLIC CAPITAL LETTER IO
+ charactersSet.add((0x0451, "\u0435")) # CYRILLIC SMALL LETTER IO
+
+ # Symbols of "Letterlike Symbols" Unicode Block (U+2100 to U+214F)
+ charactersSet.add((0x2103, "\xb0C")) # DEGREE CELSIUS
+ charactersSet.add((0x2109, "\xb0F")) # DEGREE FAHRENHEIT
+ charactersSet.add((0x2117, "(P)")) # SOUND RECORDING COPYRIGHT
+
+ return charactersSet
+
+
+def main(args):
+ # https://www.unicode.org/reports/tr44/tr44-14.html#Character_Decomposition_Mappings
+ decomposition_type_pattern = re.compile(" *<[^>]*> *")
+
+ table = {}
+ all = []
+
+ # unordered set for ensure uniqueness
+ charactersSet = set()
+
+ # read file UnicodeData.txt
+ with codecs.open(
+ args.unicodeDataFilePath, mode='r', encoding='UTF-8',
+ ) as unicodeDataFile:
+ # read everything we need into memory
+ for line in unicodeDataFile:
+ fields = line.split(";")
+ if len(fields) > 5:
+ # https://www.unicode.org/reports/tr44/tr44-14.html#UnicodeData.txt
+ general_category = fields[2]
+ decomposition = fields[5]
+ decomposition = re.sub(decomposition_type_pattern, ' ', decomposition)
+ id = int(fields[0], 16)
+ combining_ids = [int(s, 16) for s in decomposition.split(" ") if s != ""]
+ codepoint = Codepoint(id, general_category, combining_ids)
+ table[id] = codepoint
+ all.append(codepoint)
+
+ # walk through all the codepoints looking for interesting mappings
+ for codepoint in all:
+ if codepoint.general_category.startswith('L') and \
+ len(codepoint.combining_ids) > 1:
+ if is_letter_with_marks(codepoint, table):
+ charactersSet.add((codepoint.id,
+ chr(get_plain_letter(codepoint, table).id)))
+ elif args.noLigaturesExpansion is False and is_ligature(codepoint, table):
+ charactersSet.add((codepoint.id,
+ "".join(chr(combining_codepoint.id)
+ for combining_codepoint
+ in get_plain_letters(codepoint, table))))
+ elif is_mark_to_remove(codepoint):
+ charactersSet.add((codepoint.id, None))
+
+ # add CLDR Latin-ASCII characters
+ if not args.noLigaturesExpansion:
+ charactersSet |= parse_cldr_latin_ascii_transliterator(args.latinAsciiFilePath)
+ charactersSet |= special_cases()
+
+ # sort for more convenient display
+ charactersList = sorted(charactersSet, key=lambda characterPair: characterPair[0])
+
+ for characterPair in charactersList:
+ print_record(characterPair[0], characterPair[1])
+
+
+if __name__ == "__main__":
+ parser = argparse.ArgumentParser(description='This script builds unaccent.rules on standard output when given the contents of UnicodeData.txt and Latin-ASCII.xml given as arguments.')
+ parser.add_argument("--unicode-data-file", help="Path to formatted text file corresponding to UnicodeData.txt.", type=str, required=True, dest='unicodeDataFilePath')
+ parser.add_argument("--latin-ascii-file", help="Path to XML file from Unicode Common Locale Data Repository (CLDR) corresponding to Latin-ASCII transliterator (Latin-ASCII.xml).", type=str, dest='latinAsciiFilePath')
+ parser.add_argument("--no-ligatures-expansion", help="Do not expand ligatures and do not use Unicode CLDR Latin-ASCII transliterator. By default, this option is not enabled and \"--latin-ascii-file\" argument is required. If this option is enabled, \"--latin-ascii-file\" argument is optional and ignored.", action="store_true", dest='noLigaturesExpansion')
+ args = parser.parse_args()
+
+ if args.noLigaturesExpansion is False and args.latinAsciiFilePath is None:
+ sys.stderr.write('You must specify the path to Latin-ASCII transliterator file with \"--latin-ascii-file\" option or use \"--no-ligatures-expansion\" option. Use \"-h\" option for help.')
+ sys.exit(1)
+
+ main(args)