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authorThomas Wouters <thomas@python.org>2006-04-21 09:47:09 (GMT)
committerThomas Wouters <thomas@python.org>2006-04-21 09:47:09 (GMT)
commit9ada3d6e29d5165dadacbe6be07bcd35cfbef59d (patch)
tree19bca246f86e49114613e5c9f08d4ebe637ae480 /Lib/re.py
parent725ccd181020ba04bfeea41078ddb0c82c284c63 (diff)
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Merge trunk up to 43069, putting re.py back and hopefully making the branch
usable again.
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+#
+# 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.
+ "*" 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.
+ (?iLmsux) Set the I, L, M, S, U, or X flag for the RE (see 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.
+
+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].
+ \D Matches any non-digit character; equivalent to the set [^0-9].
+ \s Matches any whitespace character; equivalent to [ \t\n\r\f\v].
+ \S Matches any non-whitespace character; equiv. to [^ \t\n\r\f\v].
+ \w Matches any alphanumeric character; equivalent to [a-zA-Z0-9_].
+ 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.
+ 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.
+ compile Compile a pattern into a RegexObject.
+ purge Clear the regular expression cache.
+ escape Backslash all non-alphanumerics in a string.
+
+Some of the functions in this module takes flags as optional parameters:
+ 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 as well as the string.
+ "$" matches the end of lines as well as 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 Make \w, \W, \b, \B, dependent on the Unicode locale.
+
+This module also defines an exception 'error'.
+
+"""
+
+import sys
+import sre_compile
+import sre_parse
+
+# public symbols
+__all__ = [ "match", "search", "sub", "subn", "split", "findall",
+ "compile", "purge", "template", "escape", "I", "L", "M", "S", "X",
+ "U", "IGNORECASE", "LOCALE", "MULTILINE", "DOTALL", "VERBOSE",
+ "UNICODE", "error" ]
+
+__version__ = "2.2.1"
+
+# flags
+I = IGNORECASE = sre_compile.SRE_FLAG_IGNORECASE # ignore case
+L = LOCALE = sre_compile.SRE_FLAG_LOCALE # assume current 8-bit locale
+U = UNICODE = sre_compile.SRE_FLAG_UNICODE # assume unicode locale
+M = MULTILINE = sre_compile.SRE_FLAG_MULTILINE # make anchors look for newline
+S = DOTALL = sre_compile.SRE_FLAG_DOTALL # make dot match newline
+X = VERBOSE = sre_compile.SRE_FLAG_VERBOSE # ignore whitespace and comments
+
+# sre extensions (experimental, don't rely on these)
+T = TEMPLATE = sre_compile.SRE_FLAG_TEMPLATE # disable backtracking
+DEBUG = sre_compile.SRE_FLAG_DEBUG # dump pattern after compilation
+
+# 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 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):
+ """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 callable, it's passed the match object and must return
+ a replacement string to be used."""
+ return _compile(pattern, 0).sub(repl, string, count)
+
+def subn(pattern, repl, string, count=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 callable, it's passed the match object and must
+ return a replacement string to be used."""
+ return _compile(pattern, 0).subn(repl, string, count)
+
+def split(pattern, string, maxsplit=0):
+ """Split the source string by the occurrences of the pattern,
+ returning a list containing the resulting substrings."""
+ return _compile(pattern, 0).split(string, maxsplit)
+
+def findall(pattern, string, flags=0):
+ """Return a list of all non-overlapping matches in the string.
+
+ If one or more 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)
+
+if sys.hexversion >= 0x02020000:
+ __all__.append("finditer")
+ 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 cache"
+ _cache.clear()
+ _cache_repl.clear()
+
+def template(pattern, flags=0):
+ "Compile a template pattern, returning a pattern object"
+ return _compile(pattern, flags|T)
+
+_alphanum = {}
+for c in 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ01234567890':
+ _alphanum[c] = 1
+del c
+
+def escape(pattern):
+ "Escape all non-alphanumeric characters in pattern."
+ s = list(pattern)
+ alphanum = _alphanum
+ for i in range(len(pattern)):
+ c = pattern[i]
+ if c not in alphanum:
+ if c == "\000":
+ s[i] = "\\000"
+ else:
+ s[i] = "\\" + c
+ return pattern[:0].join(s)
+
+# --------------------------------------------------------------------
+# internals
+
+_cache = {}
+_cache_repl = {}
+
+_pattern_type = type(sre_compile.compile("", 0))
+
+_MAXCACHE = 100
+
+def _compile(*key):
+ # internal: compile pattern
+ cachekey = (type(key[0]),) + key
+ p = _cache.get(cachekey)
+ if p is not None:
+ return p
+ pattern, flags = key
+ if isinstance(pattern, _pattern_type):
+ return pattern
+ if not sre_compile.isstring(pattern):
+ raise TypeError, "first argument must be string or compiled pattern"
+ try:
+ p = sre_compile.compile(pattern, flags)
+ except error, v:
+ raise error, v # invalid expression
+ if len(_cache) >= _MAXCACHE:
+ _cache.clear()
+ _cache[cachekey] = p
+ return p
+
+def _compile_repl(*key):
+ # internal: compile replacement pattern
+ p = _cache_repl.get(key)
+ if p is not None:
+ return p
+ repl, pattern = key
+ try:
+ p = sre_parse.parse_template(repl, pattern)
+ except error, v:
+ raise error, v # invalid expression
+ if len(_cache_repl) >= _MAXCACHE:
+ _cache_repl.clear()
+ _cache_repl[key] = p
+ return p
+
+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 copy_reg
+
+def _pickle(p):
+ return _compile, (p.pattern, p.flags)
+
+copy_reg.pickle(_pattern_type, _pickle, _compile)
+
+# --------------------------------------------------------------------
+# experimental stuff (see python-dev discussions for details)
+
+class Scanner:
+ def __init__(self, lexicon, flags=0):
+ from sre_constants import BRANCH, SUBPATTERN
+ self.lexicon = lexicon
+ # combine phrases into a compound pattern
+ p = []
+ s = sre_parse.Pattern()
+ s.flags = flags
+ for phrase, action in lexicon:
+ p.append(sre_parse.SubPattern(s, [
+ (SUBPATTERN, (len(p)+1, sre_parse.parse(phrase, flags))),
+ ]))
+ p = sre_parse.SubPattern(s, [(BRANCH, (None, p))])
+ s.groups = len(p)
+ self.scanner = sre_compile.compile(p)
+ def scan(self, string):
+ result = []
+ append = result.append
+ match = self.scanner.scanner(string).match
+ i = 0
+ while 1:
+ 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:]