mirror of
https://github.com/python/cpython.git
synced 2025-10-30 21:21:22 +00:00
363 lines
15 KiB
Python
363 lines
15 KiB
Python
#
|
|
# 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<name>...) 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).
|
|
(?<!...) Matches if not preceded by ... (must be fixed length).
|
|
(?(id/name)yes|no) Matches yes pattern if the group with id/name matched,
|
|
the (optional) no pattern otherwise.
|
|
|
|
The special sequences consist of "\\" and a character from the list
|
|
below. If the ordinary character is not on the list, then the
|
|
resulting RE will match the second character.
|
|
\number Matches the contents of the group of the same number.
|
|
\A Matches only at the start of the string.
|
|
\Z Matches only at the end of the string.
|
|
\b Matches the empty string, but only at the start or end of a word.
|
|
\B Matches the empty string, but not at the start or end of a word.
|
|
\d Matches any decimal digit; equivalent to the set [0-9] in
|
|
bytes patterns or string patterns with the ASCII flag.
|
|
In string patterns without the ASCII flag, it will match the whole
|
|
range of Unicode digits.
|
|
\D Matches any non-digit character; equivalent to [^\d].
|
|
\s Matches any whitespace character; equivalent to [ \t\n\r\f\v] in
|
|
bytes patterns or string patterns with the ASCII flag.
|
|
In string patterns without the ASCII flag, it will match the whole
|
|
range of Unicode whitespace characters.
|
|
\S Matches any non-whitespace character; equivalent to [^\s].
|
|
\w Matches any alphanumeric character; equivalent to [a-zA-Z0-9_]
|
|
in bytes patterns or string patterns with the ASCII flag.
|
|
In string patterns without the ASCII flag, it will match the
|
|
range of Unicode alphanumeric characters (letters plus digits
|
|
plus underscore).
|
|
With LOCALE, it will match the set [0-9_] plus characters defined
|
|
as letters for the current locale.
|
|
\W Matches the complement of \w.
|
|
\\ Matches a literal backslash.
|
|
|
|
This module exports the following functions:
|
|
match Match a regular expression pattern to the beginning of a string.
|
|
fullmatch Match a regular expression pattern to all of a string.
|
|
search Search a string for the presence of a pattern.
|
|
sub Substitute occurrences of a pattern found in a string.
|
|
subn Same as sub, but also return the number of substitutions made.
|
|
split Split a string by the occurrences of a pattern.
|
|
findall Find all occurrences of a pattern in a string.
|
|
finditer Return an iterator yielding a Match object for each match.
|
|
compile Compile a pattern into a Pattern object.
|
|
purge Clear the regular expression cache.
|
|
escape Backslash all non-alphanumerics in a string.
|
|
|
|
Each function other than purge and escape can take an optional 'flags' argument
|
|
consisting of one or more of the following module constants, joined by "|".
|
|
A, L, and U are mutually exclusive.
|
|
A ASCII For string patterns, make \w, \W, \b, \B, \d, \D
|
|
match the corresponding ASCII character categories
|
|
(rather than the whole Unicode categories, which is the
|
|
default).
|
|
For bytes patterns, this flag is the only available
|
|
behaviour and needn't be specified.
|
|
I IGNORECASE Perform case-insensitive matching.
|
|
L LOCALE Make \w, \W, \b, \B, dependent on the current locale.
|
|
M MULTILINE "^" matches the beginning of lines (after a newline)
|
|
as well as the string.
|
|
"$" matches the end of lines (before a newline) as well
|
|
as the end of the string.
|
|
S DOTALL "." matches any character at all, including the newline.
|
|
X VERBOSE Ignore whitespace and comments for nicer looking RE's.
|
|
U UNICODE For compatibility only. Ignored for string patterns (it
|
|
is the default), and forbidden for bytes patterns.
|
|
|
|
This module also defines an exception 'error'.
|
|
|
|
"""
|
|
|
|
import enum
|
|
import sre_compile
|
|
import sre_parse
|
|
import functools
|
|
try:
|
|
import _locale
|
|
except ImportError:
|
|
_locale = None
|
|
|
|
|
|
# public symbols
|
|
__all__ = [
|
|
"match", "fullmatch", "search", "sub", "subn", "split",
|
|
"findall", "finditer", "compile", "purge", "template", "escape",
|
|
"error", "Pattern", "Match", "A", "I", "L", "M", "S", "X", "U",
|
|
"ASCII", "IGNORECASE", "LOCALE", "MULTILINE", "DOTALL", "VERBOSE",
|
|
"UNICODE",
|
|
]
|
|
|
|
__version__ = "2.2.1"
|
|
|
|
@enum.global_enum
|
|
@enum._simple_enum(enum.IntFlag, boundary=enum.KEEP)
|
|
class RegexFlag:
|
|
ASCII = A = sre_compile.SRE_FLAG_ASCII # assume ascii "locale"
|
|
IGNORECASE = I = sre_compile.SRE_FLAG_IGNORECASE # ignore case
|
|
LOCALE = L = sre_compile.SRE_FLAG_LOCALE # assume current 8-bit locale
|
|
UNICODE = U = sre_compile.SRE_FLAG_UNICODE # assume unicode "locale"
|
|
MULTILINE = M = sre_compile.SRE_FLAG_MULTILINE # make anchors look for newline
|
|
DOTALL = S = sre_compile.SRE_FLAG_DOTALL # make dot match newline
|
|
VERBOSE = X = sre_compile.SRE_FLAG_VERBOSE # ignore whitespace and comments
|
|
# sre extensions (experimental, don't rely on these)
|
|
TEMPLATE = T = sre_compile.SRE_FLAG_TEMPLATE # disable backtracking
|
|
DEBUG = sre_compile.SRE_FLAG_DEBUG # dump pattern after compilation
|
|
__str__ = object.__str__
|
|
_numeric_repr_ = hex
|
|
|
|
# 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:]
|