cpython/Lib/re.py

291 lines
7.6 KiB
Python

#!/usr/bin/env python
# -*- mode: python -*-
import sys
import string
from pcre import *
#
# First, the public part of the interface:
#
# pcre.error and re.error should be the same, since exceptions can be
# raised from either module.
# compilation flags
I = IGNORECASE
L = LOCALE
M = MULTILINE
S = DOTALL
X = VERBOSE
#
#
#
_cache = {}
_MAXCACHE = 20
def _cachecompile(pattern, flags=0):
key = (pattern, flags)
try:
return _cache[key]
except KeyError:
pass
value = compile(pattern, flags)
if len(_cache) >= _MAXCACHE:
_cache.clear()
_cache[key] = value
return value
def match(pattern, string, flags=0):
return _cachecompile(pattern, flags).match(string)
def search(pattern, string, flags=0):
return _cachecompile(pattern, flags).search(string)
def sub(pattern, repl, string, count=0):
if type(pattern) == type(''):
pattern = _cachecompile(pattern)
return pattern.sub(repl, string, count)
def subn(pattern, repl, string, count=0):
if type(pattern) == type(''):
pattern = _cachecompile(pattern)
return pattern.subn(repl, string, count)
def split(pattern, string, maxsplit=0):
if type(pattern) == type(''):
pattern = _cachecompile(pattern)
return pattern.split(string, maxsplit)
def escape(pattern):
"Escape all non-alphanumeric characters in pattern."
result = []
alphanum=string.letters+'_'+string.digits
for char in pattern:
if char not in alphanum:
result.append('\\')
result.append(char)
return string.join(result, '')
def compile(pattern, flags=0):
"Compile a regular expression pattern, returning a RegexObject."
groupindex={}
code=pcre_compile(pattern, flags, groupindex)
return RegexObject(pattern, flags, code, groupindex)
#
# Class definitions
#
class RegexObject:
def __init__(self, pattern, flags, code, groupindex):
self.code = code
self.flags = flags
self.pattern = pattern
self.groupindex = groupindex
def search(self, string, pos=0, endpos=None):
"""Scan through string looking for a match to the pattern, returning
a MatchObject instance, or None if no match was found."""
if endpos is None or endpos>len(string):
endpos=len(string)
if endpos<pos: endpos=pos
regs = self.code.match(string, pos, endpos, 0)
if regs is None:
return None
self._num_regs=len(regs)
return MatchObject(self,
string,
pos, endpos,
regs)
def match(self, string, pos=0, endpos=None):
"""Try to apply the pattern at the start of the string, returning
a MatchObject instance, or None if no match was found."""
if endpos is None or endpos>len(string):
endpos=len(string)
if endpos<pos: endpos=pos
regs = self.code.match(string, pos, endpos, ANCHORED)
if regs is None:
return None
self._num_regs=len(regs)
return MatchObject(self,
string,
pos, endpos,
regs)
def sub(self, repl, string, count=0):
"""Return the string obtained by replacing the leftmost
non-overlapping occurrences of the pattern in string by the
replacement repl"""
return self.subn(repl, string, count)[0]
def subn(self, repl, source, 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 string by the
replacement repl. number is the number of substitutions that
were made."""
if count < 0:
raise error, "negative substitution count"
if count == 0:
import sys
count = sys.maxint
if type(repl) == type(''):
if '\\' in repl:
repl = lambda m, r=repl: pcre_expand(m, r)
else:
repl = lambda m, r=repl: r
n = 0 # Number of matches
pos = 0 # Where to start searching
lastmatch = -1 # End of last match
results = [] # Substrings making up the result
end = len(source)
while n < count and pos <= end:
m = self.search(source, pos)
if not m:
break
i, j = m.span(0)
if i == j == lastmatch:
# Empty match adjacent to previous match
pos = pos + 1
results.append(source[lastmatch:pos])
continue
if pos < i:
results.append(source[pos:i])
results.append(repl(m))
pos = lastmatch = j
if i == j:
# Last match was empty; don't try here again
pos = pos + 1
results.append(source[lastmatch:pos])
n = n + 1
results.append(source[pos:])
return (string.join(results, ''), n)
def split(self, source, maxsplit=0):
"""Split \var{string} by the occurrences of the pattern,
returning a list containing the resulting substrings."""
if maxsplit < 0:
raise error, "negative split count"
if maxsplit == 0:
import sys
maxsplit = sys.maxint
n = 0
pos = 0
lastmatch = 0
results = []
end = len(source)
while n < maxsplit:
m = self.search(source, pos)
if not m:
break
i, j = m.span(0)
if i == j:
# Empty match
if pos >= end:
break
pos = pos+1
continue
results.append(source[lastmatch:i])
g = m.groups()
if g:
if type(g)==type( "" ): g = [g]
results[len(results):] = list(g)
pos = lastmatch = j
results.append(source[lastmatch:])
return results
# The following 3 functions were contributed by Mike Fletcher, and
# allow pickling and unpickling of RegexObject instances.
def __getinitargs__(self):
return (None,None,None,None) # any 4 elements, to work around
# problems with the
# pickle/cPickle modules not yet
# ignoring the __init__ function
def __getstate__(self):
return self.pattern, self.flags, self.groupindex
def __setstate__(self, statetuple):
self.pattern = statetuple[0]
self.flags = statetuple[1]
self.groupindex = statetuple[2]
self.code = apply(pcre_compile, statetuple)
class MatchObject:
def __init__(self, re, string, pos, endpos, regs):
self.re = re
self.string = string
self.pos = pos
self.endpos = endpos
self.regs = regs
def start(self, g = 0):
"Return the start of the substring matched by group g"
if type(g) == type(''):
try:
g = self.re.groupindex[g]
except (KeyError, TypeError):
raise IndexError, ('group "' + g + '" is undefined')
return self.regs[g][0]
def end(self, g = 0):
"Return the end of the substring matched by group g"
if type(g) == type(''):
try:
g = self.re.groupindex[g]
except (KeyError, TypeError):
raise IndexError, ('group "' + g + '" is undefined')
return self.regs[g][1]
def span(self, g = 0):
"""Return a tuple containing the start,end of the substring
matched by group g"""
if type(g) == type(''):
try:
g = self.re.groupindex[g]
except (KeyError, TypeError):
raise IndexError, ('group "' + g + '" is undefined')
return self.regs[g]
def groups(self):
"Return a tuple containing all subgroups of the match object"
# If _num_regs==1, we don't want to call self.group with an
# empty tuple.
if self.re._num_regs == 1: return ()
return apply(self.group, tuple(range(1, self.re._num_regs) ) )
def group(self, *groups):
"Return one or more groups of the match."
if len(groups) == 0:
groups = (0,)
result = []
for g in groups:
if type(g) == type(''):
try:
g = self.re.groupindex[g]
except (KeyError, TypeError):
raise IndexError, ('group "' + g + '" is undefined')
if len(self.regs)<=g: raise IndexError, ('group "' + str(g) + '" is undefined')
elif (self.regs[g][0] == -1) or (self.regs[g][1] == -1):
result.append(None)
else:
result.append(self.string[self.regs[g][0]:self.regs[g][1]])
if len(result) > 1:
return tuple(result)
elif len(result) == 1:
return result[0]
else:
return ()