Edit: /usr/lib64/python3.9/re.py (15861B)
#
# Secret Labs' Regular Expression Engine
#
# re-compatible interface for the sre matching engine
#
# Copyright (c) 1998-2001 by Secret Labs AB. All rights reserved.
#
# This version of the SRE library can be redistributed under CNRI's
# Python 1.6 license. For any other use, please contact Secret Labs
# AB (info@pythonware.com).
#
# Portions of this engine have been developed in cooperation with
# CNRI. Hewlett-Packard provided funding for 1.6 integration and
# other compatibility work.
#
r"""Support for regular expressions (RE).
This module provides regular expression matching operations similar to
those found in Perl. It supports both 8-bit and Unicode strings; both
the pattern and the strings being processed can contain null bytes and
characters outside the US ASCII range.
Regular expressions can contain both special and ordinary characters.
Most ordinary characters, like "A", "a", or "0", are the simplest
regular expressions; they simply match themselves. You can
concatenate ordinary characters, so last matches the string 'last'.
The special characters are:
"." Matches any character except a newline.
"^" Matches the start of the string.
"$" Matches the end of the string or just before the newline at
the end of the string.
"*" Matches 0 or more (greedy) repetitions of the preceding RE.
Greedy means that it will match as many repetitions as possible.
"+" Matches 1 or more (greedy) repetitions of the preceding RE.
"?" Matches 0 or 1 (greedy) of the preceding RE.
*?,+?,?? Non-greedy versions of the previous three special characters.
{m,n} Matches from m to n repetitions of the preceding RE.
{m,n}? Non-greedy version of the above.
"\\" Either escapes special characters or signals a special sequence.
[] Indicates a set of characters.
A "^" as the first character indicates a complementing set.
"|" A|B, creates an RE that will match either A or B.
(...) Matches the RE inside the parentheses.
The contents can be retrieved or matched later in the string.
(?aiLmsux) The letters set the corresponding flags defined below.
(?:...) Non-grouping version of regular parentheses.
(?P
...) The substring matched by the group is accessible by name.
(?P=name) Matches the text matched earlier by the group named name.
(?#...) A comment; ignored.
(?=...) Matches if ... matches next, but doesn't consume the string.
(?!...) Matches if ... doesn't match next.
(?<=...) Matches if preceded by ... (must be fixed length).
(? 1:
res = f'~({res})'
else:
res = f'~{res}'
return res
__str__ = object.__str__
globals().update(RegexFlag.__members__)
# sre exception
error = sre_compile.error
# --------------------------------------------------------------------
# public interface
def match(pattern, string, flags=0):
"""Try to apply the pattern at the start of the string, returning
a Match object, or None if no match was found."""
return _compile(pattern, flags).match(string)
def fullmatch(pattern, string, flags=0):
"""Try to apply the pattern to all of the string, returning
a Match object, or None if no match was found."""
return _compile(pattern, flags).fullmatch(string)
def search(pattern, string, flags=0):
"""Scan through string looking for a match to the pattern, returning
a Match object, or None if no match was found."""
return _compile(pattern, flags).search(string)
def sub(pattern, repl, string, count=0, flags=0):
"""Return the string obtained by replacing the leftmost
non-overlapping occurrences of the pattern in string by the
replacement repl. repl can be either a string or a callable;
if a string, backslash escapes in it are processed. If it is
a callable, it's passed the Match object and must return
a replacement string to be used."""
return _compile(pattern, flags).sub(repl, string, count)
def subn(pattern, repl, string, count=0, flags=0):
"""Return a 2-tuple containing (new_string, number).
new_string is the string obtained by replacing the leftmost
non-overlapping occurrences of the pattern in the source
string by the replacement repl. number is the number of
substitutions that were made. repl can be either a string or a
callable; if a string, backslash escapes in it are processed.
If it is a callable, it's passed the Match object and must
return a replacement string to be used."""
return _compile(pattern, flags).subn(repl, string, count)
def split(pattern, string, maxsplit=0, flags=0):
"""Split the source string by the occurrences of the pattern,
returning a list containing the resulting substrings. If
capturing parentheses are used in pattern, then the text of all
groups in the pattern are also returned as part of the resulting
list. If maxsplit is nonzero, at most maxsplit splits occur,
and the remainder of the string is returned as the final element
of the list."""
return _compile(pattern, flags).split(string, maxsplit)
def findall(pattern, string, flags=0):
"""Return a list of all non-overlapping matches in the string.
If one or more capturing groups are present in the pattern, return
a list of groups; this will be a list of tuples if the pattern
has more than one group.
Empty matches are included in the result."""
return _compile(pattern, flags).findall(string)
def finditer(pattern, string, flags=0):
"""Return an iterator over all non-overlapping matches in the
string. For each match, the iterator returns a Match object.
Empty matches are included in the result."""
return _compile(pattern, flags).finditer(string)
def compile(pattern, flags=0):
"Compile a regular expression pattern, returning a Pattern object."
return _compile(pattern, flags)
def purge():
"Clear the regular expression caches"
_cache.clear()
_compile_repl.cache_clear()
def template(pattern, flags=0):
"Compile a template pattern, returning a Pattern object"
return _compile(pattern, flags|T)
# SPECIAL_CHARS
# closing ')', '}' and ']'
# '-' (a range in character set)
# '&', '~', (extended character set operations)
# '#' (comment) and WHITESPACE (ignored) in verbose mode
_special_chars_map = {i: '\\' + chr(i) for i in b'()[]{}?*+-|^$\\.&~# \t\n\r\v\f'}
def escape(pattern):
"""
Escape special characters in a string.
"""
if isinstance(pattern, str):
return pattern.translate(_special_chars_map)
else:
pattern = str(pattern, 'latin1')
return pattern.translate(_special_chars_map).encode('latin1')
Pattern = type(sre_compile.compile('', 0))
Match = type(sre_compile.compile('', 0).match(''))
# --------------------------------------------------------------------
# internals
_cache = {} # ordered!
_MAXCACHE = 512
def _compile(pattern, flags):
# internal: compile pattern
if isinstance(flags, RegexFlag):
flags = flags.value
try:
return _cache[type(pattern), pattern, flags]
except KeyError:
pass
if isinstance(pattern, Pattern):
if flags:
raise ValueError(
"cannot process flags argument with a compiled pattern")
return pattern
if not sre_compile.isstring(pattern):
raise TypeError("first argument must be string or compiled pattern")
p = sre_compile.compile(pattern, flags)
if not (flags & DEBUG):
if len(_cache) >= _MAXCACHE:
# Drop the oldest item
try:
del _cache[next(iter(_cache))]
except (StopIteration, RuntimeError, KeyError):
pass
_cache[type(pattern), pattern, flags] = p
return p
@functools.lru_cache(_MAXCACHE)
def _compile_repl(repl, pattern):
# internal: compile replacement pattern
return sre_parse.parse_template(repl, pattern)
def _expand(pattern, match, template):
# internal: Match.expand implementation hook
template = sre_parse.parse_template(template, pattern)
return sre_parse.expand_template(template, match)
def _subx(pattern, template):
# internal: Pattern.sub/subn implementation helper
template = _compile_repl(template, pattern)
if not template[0] and len(template[1]) == 1:
# literal replacement
return template[1][0]
def filter(match, template=template):
return sre_parse.expand_template(template, match)
return filter
# register myself for pickling
import copyreg
def _pickle(p):
return _compile, (p.pattern, p.flags)
copyreg.pickle(Pattern, _pickle, _compile)
# --------------------------------------------------------------------
# experimental stuff (see python-dev discussions for details)
class Scanner:
def __init__(self, lexicon, flags=0):
from sre_constants import BRANCH, SUBPATTERN
if isinstance(flags, RegexFlag):
flags = flags.value
self.lexicon = lexicon
# combine phrases into a compound pattern
p = []
s = sre_parse.State()
s.flags = flags
for phrase, action in lexicon:
gid = s.opengroup()
p.append(sre_parse.SubPattern(s, [
(SUBPATTERN, (gid, 0, 0, sre_parse.parse(phrase, flags))),
]))
s.closegroup(gid, p[-1])
p = sre_parse.SubPattern(s, [(BRANCH, (None, p))])
self.scanner = sre_compile.compile(p)
def scan(self, string):
result = []
append = result.append
match = self.scanner.scanner(string).match
i = 0
while True:
m = match()
if not m:
break
j = m.end()
if i == j:
break
action = self.lexicon[m.lastindex-1][1]
if callable(action):
self.match = m
action = action(self, m.group())
if action is not None:
append(action)
i = j
return result, string[i:]