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mirror of https://github.com/python/cpython.git synced 2024-11-30 10:41:14 +01:00
cpython/Lib/re.py
Andrew M. Kuchling 9a80e00cac The .subn() method wasn't setting _num_regs, which is used by the .groups()
method, so .groups() didn't work inside the replacement function
	called by re.sub.  One-line fix: set self._num_regs inside subn().
1998-08-21 18:39:38 +00:00

370 lines
11 KiB
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 findall(pattern, string):
if type(pattern) == type(''):
pattern = _cachecompile(pattern)
return pattern.findall(string)
def escape(pattern):
"Escape all non-alphanumeric characters in pattern."
result = list(pattern)
alphanum=string.letters+'_'+string.digits
for i in range(len(pattern)):
char = pattern[i]
if char not in alphanum:
if char=='\000': result[i] = '\\000'
else: result[i] = '\\'+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 the source
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:
count = sys.maxint
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)
if type(repl) is type(''):
# See if repl contains group references
try:
repl = pcre_expand(_Dummy, repl)
except:
m = MatchObject(self, source, 0, end, [])
repl = lambda m, repl=repl, expand=pcre_expand: expand(m, repl)
else:
m = None
else:
m = MatchObject(self, source, 0, end, [])
match = self.code.match
append = results.append
while n < count and pos <= end:
regs = match(source, pos, end, 0)
if not regs:
break
self._num_regs = len(regs)
i, j = regs[0]
if i == j == lastmatch:
# Empty match adjacent to previous match
pos = pos + 1
append(source[lastmatch:pos])
continue
if pos < i:
append(source[pos:i])
if m:
m.pos = pos
m.regs = regs
append(repl(m))
else:
append(repl)
pos = lastmatch = j
if i == j:
# Last match was empty; don't try here again
pos = pos + 1
append(source[lastmatch:pos])
n = n + 1
append(source[pos:])
return (string.join(results, ''), n)
def split(self, source, maxsplit=0):
"""Split the source 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:
maxsplit = sys.maxint
n = 0
pos = 0
lastmatch = 0
results = []
end = len(source)
match = self.code.match
append = results.append
while n < maxsplit:
regs = match(source, pos, end, 0)
if not regs:
break
i, j = regs[0]
if i == j:
# Empty match
if pos >= end:
break
pos = pos+1
continue
append(source[lastmatch:i])
rest = regs[1:]
if rest:
for a, b in rest:
if a == -1 or b == -1:
group = None
else:
group = source[a:b]
append(group)
pos = lastmatch = j
n = n + 1
append(source[lastmatch:])
return results
def findall(self, source):
"""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.
"""
pos = 0
end = len(source)
results = []
match = self.code.match
append = results.append
while pos <= end:
regs = match(source, pos, end, 0)
if not regs:
break
i, j = regs[0]
rest = regs[1:]
if not rest:
gr = source[i:j]
elif len(rest) == 1:
a, b = rest[0]
gr = source[a:b]
else:
gr = []
for (a, b) in rest:
gr.append(source[a:b])
gr = tuple(gr)
append(gr)
pos = max(j, pos+1)
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 _Dummy:
# Dummy class used by _subn_string(). Has 'group' to avoid core dump.
group = None
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 %s is undefined' % `g`
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 %s is undefined' % `g`
return self.regs[g][1]
def span(self, g = 0):
"Return (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 %s is undefined' % `g`
return self.regs[g]
def groups(self, default=None):
"Return a tuple containing all subgroups of the match object"
result = []
for g in range(1, self.re._num_regs):
a, b = self.regs[g]
if a == -1 or b == -1:
result.append(default)
else:
result.append(self.string[a:b])
return tuple(result)
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 %s is undefined' % `g`
if g >= len(self.regs):
raise IndexError, 'group %s is undefined' % `g`
a, b = self.regs[g]
if a == -1 or b == -1:
result.append(None)
else:
result.append(self.string[a:b])
if len(result) > 1:
return tuple(result)
elif len(result) == 1:
return result[0]
else:
return ()
def groupdict(self, default=None):
"Return a dictionary containing all named subgroups of the match"
dict = {}
for name, index in self.re.groupindex.items():
a, b = self.regs[index]
if a == -1 or b == -1:
dict[name] = default
else:
dict[name] = self.string[a:b]
return dict