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315cd29ecf
bug #449000, "re.sub(r'\n', ...) broke". This was Fredrik's suggestion -- he's on vacation and said he wouldn't be able to work on this until next week.
268 lines
8.2 KiB
Python
268 lines
8.2 KiB
Python
#
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# Secret Labs' Regular Expression Engine
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#
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# re-compatible interface for the sre matching engine
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#
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# Copyright (c) 1998-2001 by Secret Labs AB. All rights reserved.
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#
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# This version of the SRE library can be redistributed under CNRI's
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# Python 1.6 license. For any other use, please contact Secret Labs
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# AB (info@pythonware.com).
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#
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# Portions of this engine have been developed in cooperation with
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# CNRI. Hewlett-Packard provided funding for 1.6 integration and
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# other compatibility work.
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#
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import sre_compile
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import sre_parse
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# public symbols
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__all__ = [ "match", "search", "sub", "subn", "split", "findall",
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"compile", "purge", "template", "escape", "I", "L", "M", "S", "X",
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"U", "IGNORECASE", "LOCALE", "MULTILINE", "DOTALL", "VERBOSE",
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"UNICODE", "error" ]
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__version__ = "2.1b2"
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# this module works under 1.5.2 and later. don't use string methods
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import string
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# flags
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I = IGNORECASE = sre_compile.SRE_FLAG_IGNORECASE # ignore case
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L = LOCALE = sre_compile.SRE_FLAG_LOCALE # assume current 8-bit locale
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U = UNICODE = sre_compile.SRE_FLAG_UNICODE # assume unicode locale
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M = MULTILINE = sre_compile.SRE_FLAG_MULTILINE # make anchors look for newline
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S = DOTALL = sre_compile.SRE_FLAG_DOTALL # make dot match newline
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X = VERBOSE = sre_compile.SRE_FLAG_VERBOSE # ignore whitespace and comments
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# sre extensions (experimental, don't rely on these)
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T = TEMPLATE = sre_compile.SRE_FLAG_TEMPLATE # disable backtracking
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DEBUG = sre_compile.SRE_FLAG_DEBUG # dump pattern after compilation
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# sre exception
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error = sre_compile.error
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# --------------------------------------------------------------------
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# public interface
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def match(pattern, string, flags=0):
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"""Try to apply the pattern at the start of the string, returning
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a match object, or None if no match was found."""
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return _compile(pattern, flags).match(string)
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def search(pattern, string, flags=0):
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"""Scan through string looking for a match to the pattern, returning
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a match object, or None if no match was found."""
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return _compile(pattern, flags).search(string)
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def sub(pattern, repl, string, count=0):
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"""Return the string obtained by replacing the leftmost
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non-overlapping occurrences of the pattern in string by the
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replacement repl"""
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return _compile(pattern, 0).sub(repl, string, count)
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def subn(pattern, repl, string, count=0):
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"""Return a 2-tuple containing (new_string, number).
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new_string is the string obtained by replacing the leftmost
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non-overlapping occurrences of the pattern in the source
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string by the replacement repl. number is the number of
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substitutions that were made."""
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return _compile(pattern, 0).subn(repl, string, count)
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def split(pattern, string, maxsplit=0):
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"""Split the source string by the occurrences of the pattern,
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returning a list containing the resulting substrings."""
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return _compile(pattern, 0).split(string, maxsplit)
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def findall(pattern, string):
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"""Return a list of all non-overlapping matches in the string.
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If one or more groups are present in the pattern, return a
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list of groups; this will be a list of tuples if the pattern
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has more than one group.
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Empty matches are included in the result."""
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return _compile(pattern, 0).findall(string)
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def compile(pattern, flags=0):
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"Compile a regular expression pattern, returning a pattern object."
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return _compile(pattern, flags)
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def purge():
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"Clear the regular expression cache"
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_cache.clear()
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_cache_repl.clear()
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def template(pattern, flags=0):
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"Compile a template pattern, returning a pattern object"
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return _compile(pattern, flags|T)
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def escape(pattern):
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"Escape all non-alphanumeric characters in pattern."
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s = list(pattern)
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for i in range(len(pattern)):
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c = pattern[i]
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if not ("a" <= c <= "z" or "A" <= c <= "Z" or "0" <= c <= "9"):
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if c == "\000":
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s[i] = "\\000"
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else:
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s[i] = "\\" + c
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return _join(s, pattern)
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# --------------------------------------------------------------------
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# internals
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_cache = {}
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_cache_repl = {}
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_MAXCACHE = 100
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def _join(seq, sep):
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# internal: join into string having the same type as sep
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return string.join(seq, sep[:0])
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def _compile(*key):
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# internal: compile pattern
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p = _cache.get(key)
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if p is not None:
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return p
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pattern, flags = key
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if type(pattern) not in sre_compile.STRING_TYPES:
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return pattern
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try:
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p = sre_compile.compile(pattern, flags)
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except error, v:
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raise error, v # invalid expression
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if len(_cache) >= _MAXCACHE:
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_cache.clear()
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_cache[key] = p
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return p
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def _compile_repl(*key):
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# internal: compile replacement pattern
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p = _cache_repl.get(key)
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if p is not None:
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return p
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repl, pattern = key
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try:
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p = sre_parse.parse_template(repl, pattern)
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except error, v:
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raise error, v # invalid expression
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if len(_cache_repl) >= _MAXCACHE:
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_cache_repl.clear()
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_cache_repl[key] = p
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return p
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def _expand(pattern, match, template):
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# internal: match.expand implementation hook
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template = sre_parse.parse_template(template, pattern)
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return sre_parse.expand_template(template, match)
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def _sub(pattern, template, text, count=0):
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# internal: pattern.sub implementation hook
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return _subn(pattern, template, text, count, 1)[0]
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def _subn(pattern, template, text, count=0, sub=0):
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# internal: pattern.subn implementation hook
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if callable(template):
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filter = template
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else:
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template = _compile_repl(template, pattern)
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literals = template[1]
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sub = 0 # temporarly disabled, see bug #449000
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if (sub and not count and pattern._isliteral() and
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len(literals) == 1 and literals[0]):
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# shortcut: both pattern and string are literals
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return string.replace(text, pattern.pattern, literals[0]), 0
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def filter(match, template=template):
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return sre_parse.expand_template(template, match)
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n = i = 0
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s = []
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append = s.append
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c = pattern.scanner(text)
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while not count or n < count:
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m = c.search()
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if not m:
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break
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b, e = m.span()
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if i < b:
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append(text[i:b])
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append(filter(m))
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i = e
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n = n + 1
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append(text[i:])
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return _join(s, text[:0]), n
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def _split(pattern, text, maxsplit=0):
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# internal: pattern.split implementation hook
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n = i = 0
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s = []
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append = s.append
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extend = s.extend
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c = pattern.scanner(text)
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g = pattern.groups
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while not maxsplit or n < maxsplit:
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m = c.search()
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if not m:
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break
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b, e = m.span()
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if b == e:
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if i >= len(text):
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break
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continue
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append(text[i:b])
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if g and b != e:
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extend(list(m.groups()))
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i = e
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n = n + 1
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append(text[i:])
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return s
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# register myself for pickling
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import copy_reg
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def _pickle(p):
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return _compile, (p.pattern, p.flags)
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copy_reg.pickle(type(_compile("", 0)), _pickle, _compile)
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# --------------------------------------------------------------------
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# experimental stuff (see python-dev discussions for details)
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class Scanner:
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def __init__(self, lexicon):
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from sre_constants import BRANCH, SUBPATTERN
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self.lexicon = lexicon
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# combine phrases into a compound pattern
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p = []
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s = sre_parse.Pattern()
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for phrase, action in lexicon:
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p.append(sre_parse.SubPattern(s, [
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(SUBPATTERN, (len(p), sre_parse.parse(phrase))),
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]))
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p = sre_parse.SubPattern(s, [(BRANCH, (None, p))])
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s.groups = len(p)
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self.scanner = sre_compile.compile(p)
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def scan(self, string):
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result = []
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append = result.append
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match = self.scanner.match
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i = 0
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while 1:
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m = match(string, i)
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if not m:
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break
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j = m.end()
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if i == j:
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break
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action = self.lexicon[m.lastindex][1]
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if callable(action):
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self.match = m
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action = action(self, m.group())
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if action is not None:
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append(action)
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i = j
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return result, string[i:]
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