wordfreq/scripts/gen_regex.py
Andrew Lin 2262088b5f Improve variable names.
Former-commit-id: 95da6985d4
2015-07-10 14:02:33 -04:00

78 lines
2.6 KiB
Python

import unicodedata
from ftfy import chardata
import pathlib
from pkg_resources import resource_filename
CATEGORIES = [unicodedata.category(chr(i)) for i in range(0x110000)]
DATA_PATH = pathlib.Path(resource_filename('wordfreq', 'data'))
def func_to_regex(accept_func):
"""
Given a function that returns True or False for a numerical codepoint,
return a regex character class accepting the characters resulting in True.
Ranges separated only by unassigned characters are merged for efficiency.
"""
# Where the last range would end if it also included unassigned codepoints.
# If we need to add a codepoint right after this point, we extend the
# range; otherwise we start a new one.
tentative_end = None
ranges = []
for codepoint, category in enumerate(CATEGORIES):
if accept_func(codepoint):
if tentative_end == codepoint - 1:
ranges[-1][1] = codepoint
else:
ranges.append([codepoint, codepoint])
tentative_end = codepoint
elif category == 'Cn' and tentative_end == codepoint - 1:
tentative_end = codepoint
return '[%s]' % ''.join(chr(r[0]) + '-' + chr(r[1]) for r in ranges)
def cache_regex_from_func(filename, func):
"""
Generates a regex from a function that accepts a single unicode character,
and caches it in the data path at filename.
"""
with (DATA_PATH / filename).open(mode='w') as file:
file.write(func_to_regex(func))
def _is_emoji_codepoint(i):
"""
Report whether a numerical codepoint is (likely) an emoji: a Unicode 'So'
character (as future-proofed by the ftfy chardata module) but excluding
symbols like © and ™ below U+2600 and the replacement character U+FFFD.
"""
return chardata.CHAR_CLASS_STRING[i] == '3' and i >= 0x2600 and i != 0xfffd
def _is_non_punct_codepoint(i):
"""
Report whether a numerical codepoint is not one of the following classes:
- P: punctuation
- S: symbols
- Z: separators
- C: control characters
This will classify symbols, including emoji, as punctuation; users that
want to accept emoji should add them separately.
"""
return CATEGORIES[i][0] not in 'PSZC'
def _is_combining_mark_codepoint(i):
"""
Report whether a numerical codepoint is a combining mark (Unicode 'M').
"""
return CATEGORIES[i][0] == 'M'
if __name__ == '__main__':
cache_regex_from_func('emoji.txt', _is_emoji_codepoint)
cache_regex_from_func('non_punct.txt', _is_non_punct_codepoint)
cache_regex_from_func('combining_mark.txt', _is_combining_mark_codepoint)