mirror of
https://github.com/python/cpython.git
synced 2024-11-28 12:31:14 +08:00
651 lines
23 KiB
Python
651 lines
23 KiB
Python
# module 're' -- A collection of regular expression operations
|
|
|
|
"""Support for regular expressions (RE).
|
|
|
|
This module provides regular expression matching operations similar to
|
|
those found in Perl. It's 8-bit clean: the strings being processed may
|
|
contain both null bytes and characters whose high bit is set. Regular
|
|
expression pattern strings may not contain null bytes, but can specify
|
|
the null byte using the \\number notation. Characters with the high
|
|
bit set may be included.
|
|
|
|
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.
|
|
(?iLmsx) Set the I, L, M, S, or X flag for the RE.
|
|
(?:...) 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.
|
|
escape Backslash all non-alphanumerics in a string.
|
|
|
|
This module exports the following classes:
|
|
RegexObject Holds a compiled regular expression pattern.
|
|
MatchObject Contains information about pattern matches.
|
|
|
|
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.
|
|
|
|
This module also defines an exception 'error'.
|
|
|
|
"""
|
|
|
|
|
|
import sys
|
|
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):
|
|
"""match (pattern, string[, flags]) -> MatchObject or None
|
|
|
|
If zero or more characters at the beginning of string match the
|
|
regular expression pattern, return a corresponding MatchObject
|
|
instance. Return None if the string does not match the pattern;
|
|
note that this is different from a zero-length match.
|
|
|
|
Note: If you want to locate a match anywhere in string, use
|
|
search() instead.
|
|
|
|
"""
|
|
|
|
return _cachecompile(pattern, flags).match(string)
|
|
|
|
def search(pattern, string, flags=0):
|
|
"""search (pattern, string[, flags]) -> MatchObject or None
|
|
|
|
Scan through string looking for a location where the regular
|
|
expression pattern produces a match, and return a corresponding
|
|
MatchObject instance. Return None if no position in the string
|
|
matches the pattern; note that this is different from finding a
|
|
zero-length match at some point in the string.
|
|
|
|
"""
|
|
return _cachecompile(pattern, flags).search(string)
|
|
|
|
def sub(pattern, repl, string, count=0):
|
|
"""sub(pattern, repl, string[, count=0]) -> string
|
|
|
|
Return the string obtained by replacing the leftmost
|
|
non-overlapping occurrences of pattern in string by the
|
|
replacement repl. If the pattern isn't found, string is returned
|
|
unchanged. repl can be a string or a function; if a function, it
|
|
is called for every non-overlapping occurrence of pattern. The
|
|
function takes a single match object argument, and returns the
|
|
replacement string.
|
|
|
|
The pattern may be a string or a regex object; if you need to
|
|
specify regular expression flags, you must use a regex object, or
|
|
use embedded modifiers in a pattern; e.g.
|
|
sub("(?i)b+", "x", "bbbb BBBB") returns 'x x'.
|
|
|
|
The optional argument count is the maximum number of pattern
|
|
occurrences to be replaced; count must be a non-negative integer,
|
|
and the default value of 0 means to replace all occurrences.
|
|
|
|
"""
|
|
if type(pattern) == type(''):
|
|
pattern = _cachecompile(pattern)
|
|
return pattern.sub(repl, string, count)
|
|
|
|
def subn(pattern, repl, string, count=0):
|
|
"""subn(pattern, repl, string[, count=0]) -> (string, num substitutions)
|
|
|
|
Perform the same operation as sub(), but return a tuple
|
|
(new_string, number_of_subs_made).
|
|
|
|
"""
|
|
if type(pattern) == type(''):
|
|
pattern = _cachecompile(pattern)
|
|
return pattern.subn(repl, string, count)
|
|
|
|
def split(pattern, string, maxsplit=0):
|
|
"""split(pattern, string[, maxsplit=0]) -> list of strings
|
|
|
|
Split string by the occurrences of pattern. 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.
|
|
|
|
"""
|
|
if type(pattern) == type(''):
|
|
pattern = _cachecompile(pattern)
|
|
return pattern.split(string, maxsplit)
|
|
|
|
def findall(pattern, string):
|
|
"""findall(pattern, string) -> list
|
|
|
|
Return a list of all non-overlapping matches of pattern in
|
|
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.
|
|
|
|
"""
|
|
if type(pattern) == type(''):
|
|
pattern = _cachecompile(pattern)
|
|
return pattern.findall(string)
|
|
|
|
def escape(pattern):
|
|
"""escape(string) -> string
|
|
|
|
Return string with all non-alphanumerics backslashed; this is
|
|
useful if you want to match an arbitrary literal string that may
|
|
have regular expression metacharacters in it.
|
|
|
|
"""
|
|
result = list(pattern)
|
|
for i in range(len(pattern)):
|
|
char = pattern[i]
|
|
if not char.isalnum():
|
|
if char=='\000': result[i] = '\\000'
|
|
else: result[i] = '\\'+char
|
|
return ''.join(result)
|
|
|
|
def compile(pattern, flags=0):
|
|
"""compile(pattern[, flags]) -> RegexObject
|
|
|
|
Compile a regular expression pattern into a regular expression
|
|
object, which can be used for matching using its match() and
|
|
search() methods.
|
|
|
|
"""
|
|
groupindex={}
|
|
code=pcre_compile(pattern, flags, groupindex)
|
|
return RegexObject(pattern, flags, code, groupindex)
|
|
|
|
|
|
#
|
|
# Class definitions
|
|
#
|
|
|
|
class RegexObject:
|
|
"""Holds a compiled regular expression pattern.
|
|
|
|
Methods:
|
|
match Match the pattern to the beginning of a string.
|
|
search Search a string for the presence of the pattern.
|
|
sub Substitute occurrences of the 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 the pattern.
|
|
findall Find all occurrences of the pattern in a string.
|
|
|
|
"""
|
|
|
|
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):
|
|
"""search(string[, pos][, endpos]) -> MatchObject or None
|
|
|
|
Scan through string looking for a location where this regular
|
|
expression produces a match, and return a corresponding
|
|
MatchObject instance. Return None if no position in the string
|
|
matches the pattern; note that this is different from finding
|
|
a zero-length match at some point in the string. The optional
|
|
pos and endpos parameters have the same meaning as for the
|
|
match() method.
|
|
|
|
"""
|
|
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):
|
|
"""match(string[, pos][, endpos]) -> MatchObject or None
|
|
|
|
If zero or more characters at the beginning of string match
|
|
this regular expression, return a corresponding MatchObject
|
|
instance. Return None if the string does not match the
|
|
pattern; note that this is different from a zero-length match.
|
|
|
|
Note: If you want to locate a match anywhere in string, use
|
|
search() instead.
|
|
|
|
The optional second parameter pos gives an index in the string
|
|
where the search is to start; it defaults to 0. This is not
|
|
completely equivalent to slicing the string; the '' pattern
|
|
character matches at the real beginning of the string and at
|
|
positions just after a newline, but not necessarily at the
|
|
index where the search is to start.
|
|
|
|
The optional parameter endpos limits how far the string will
|
|
be searched; it will be as if the string is endpos characters
|
|
long, so only the characters from pos to endpos will be
|
|
searched for a match.
|
|
|
|
"""
|
|
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):
|
|
"""sub(repl, string[, count=0]) -> string
|
|
|
|
Return the string obtained by replacing the leftmost
|
|
non-overlapping occurrences of the compiled pattern in string
|
|
by the replacement repl. If the pattern isn't found, string is
|
|
returned unchanged.
|
|
|
|
Identical to the sub() function, using the compiled pattern.
|
|
|
|
"""
|
|
return self.subn(repl, string, count)[0]
|
|
|
|
def subn(self, repl, source, count=0):
|
|
"""subn(repl, string[, count=0]) -> tuple
|
|
|
|
Perform the same operation as sub(), but return a tuple
|
|
(new_string, number_of_subs_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 (''.join(results), n)
|
|
|
|
def split(self, source, maxsplit=0):
|
|
"""split(source[, maxsplit=0]) -> list of strings
|
|
|
|
Split string by the occurrences of the compiled pattern. If
|
|
capturing parentheses are used in the 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.
|
|
|
|
"""
|
|
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):
|
|
"""findall(source) -> list
|
|
|
|
Return a list of all non-overlapping matches of the compiled
|
|
pattern in 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:
|
|
"""Holds a compiled regular expression pattern.
|
|
|
|
Methods:
|
|
start Return the index of the start of a matched substring.
|
|
end Return the index of the end of a matched substring.
|
|
span Return a tuple of (start, end) of a matched substring.
|
|
groups Return a tuple of all the subgroups of the match.
|
|
group Return one or more subgroups of the match.
|
|
groupdict Return a dictionary of all the named subgroups of the match.
|
|
|
|
"""
|
|
|
|
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):
|
|
"""start([group=0]) -> int or None
|
|
|
|
Return the index of the start of the substring matched by
|
|
group; group defaults to zero (meaning the whole matched
|
|
substring). Return -1 if group exists but did not contribute
|
|
to the match.
|
|
|
|
"""
|
|
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):
|
|
"""end([group=0]) -> int or None
|
|
|
|
Return the indices of the end of the substring matched by
|
|
group; group defaults to zero (meaning the whole matched
|
|
substring). Return -1 if group exists but did not contribute
|
|
to the match.
|
|
|
|
"""
|
|
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):
|
|
"""span([group=0]) -> tuple
|
|
|
|
Return the 2-tuple (m.start(group), m.end(group)). Note that
|
|
if group did not contribute to the match, this is (-1,
|
|
-1). Group defaults to zero (meaning the whole matched
|
|
substring).
|
|
|
|
"""
|
|
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):
|
|
"""groups([default=None]) -> tuple
|
|
|
|
Return a tuple containing all the subgroups of the match, from
|
|
1 up to however many groups are in the pattern. The default
|
|
argument is used for groups that did not participate in the
|
|
match.
|
|
|
|
"""
|
|
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):
|
|
"""group([group1, group2, ...]) -> string or tuple
|
|
|
|
Return one or more subgroups of the match. If there is a
|
|
single argument, the result is a single string; if there are
|
|
multiple arguments, the result is a tuple with one item per
|
|
argument. Without arguments, group1 defaults to zero (i.e. the
|
|
whole match is returned). If a groupN argument is zero, the
|
|
corresponding return value is the entire matching string; if
|
|
it is in the inclusive range [1..99], it is the string
|
|
matching the the corresponding parenthesized group. If a group
|
|
number is negative or larger than the number of groups defined
|
|
in the pattern, an IndexError exception is raised. If a group
|
|
is contained in a part of the pattern that did not match, the
|
|
corresponding result is None. If a group is contained in a
|
|
part of the pattern that matched multiple times, the last
|
|
match is returned.
|
|
|
|
If the regular expression uses the (?P<name>...) syntax, the
|
|
groupN arguments may also be strings identifying groups by
|
|
their group name. If a string argument is not used as a group
|
|
name in the pattern, an IndexError exception is raised.
|
|
|
|
"""
|
|
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):
|
|
"""groupdict([default=None]) -> dictionary
|
|
|
|
Return a dictionary containing all the named subgroups of the
|
|
match, keyed by the subgroup name. The default argument is
|
|
used for groups that did not participate in 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
|