mirror of https://github.com/python/cpython.git
358 lines
13 KiB
Python
358 lines
13 KiB
Python
#
|
|
# 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'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 (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 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__ = "2.2.0"
|
|
|
|
# this module works under 1.5.2 and later. don't use string methods
|
|
import string
|
|
|
|
# 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"""
|
|
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."""
|
|
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):
|
|
"""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, 0).findall(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)
|
|
|
|
def escape(pattern):
|
|
"Escape all non-alphanumeric characters in pattern."
|
|
s = list(pattern)
|
|
for i in range(len(pattern)):
|
|
c = pattern[i]
|
|
if not ("a" <= c <= "z" or "A" <= c <= "Z" or "0" <= c <= "9"):
|
|
if c == "\000":
|
|
s[i] = "\\000"
|
|
else:
|
|
s[i] = "\\" + c
|
|
return _join(s, pattern)
|
|
|
|
# --------------------------------------------------------------------
|
|
# internals
|
|
|
|
_cache = {}
|
|
_cache_repl = {}
|
|
|
|
_pattern_type = type(sre_compile.compile("", 0))
|
|
|
|
_MAXCACHE = 100
|
|
|
|
def _join(seq, sep):
|
|
# internal: join into string having the same type as sep
|
|
return string.join(seq, sep[:0])
|
|
|
|
def _compile(*key):
|
|
# internal: compile pattern
|
|
p = _cache.get(key)
|
|
if p is not None:
|
|
return p
|
|
pattern, flags = key
|
|
if type(pattern) is _pattern_type:
|
|
return pattern
|
|
if type(pattern) not in sre_compile.STRING_TYPES:
|
|
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[key] = 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 _sub(pattern, template, text, count=0):
|
|
# internal: pattern.sub implementation hook
|
|
return _subn(pattern, template, text, count, 1)[0]
|
|
|
|
def _subn(pattern, template, text, count=0, sub=0):
|
|
# internal: pattern.subn implementation hook
|
|
if callable(template):
|
|
filter = template
|
|
else:
|
|
template = _compile_repl(template, pattern)
|
|
literals = template[1]
|
|
if sub and not count:
|
|
literal = pattern._getliteral()
|
|
if literal and "\\" in literal:
|
|
literal = None # may contain untranslated escapes
|
|
if literal is not None and len(literals) == 1 and literals[0]:
|
|
# shortcut: both pattern and string are literals
|
|
return string.replace(text, pattern.pattern, literals[0]), 0
|
|
def filter(match, template=template):
|
|
return sre_parse.expand_template(template, match)
|
|
n = i = 0
|
|
s = []
|
|
append = s.append
|
|
c = pattern.scanner(text)
|
|
while not count or n < count:
|
|
m = c.search()
|
|
if not m:
|
|
break
|
|
b, e = m.span()
|
|
if i < b:
|
|
append(text[i:b])
|
|
elif i == b == e and n:
|
|
append(text[i:b])
|
|
continue # ignore empty match at previous position
|
|
append(filter(m))
|
|
i = e
|
|
n = n + 1
|
|
append(text[i:])
|
|
return _join(s, text[:0]), n
|
|
|
|
def _split(pattern, text, maxsplit=0):
|
|
# internal: pattern.split implementation hook
|
|
n = i = 0
|
|
s = []
|
|
append = s.append
|
|
extend = s.extend
|
|
c = pattern.scanner(text)
|
|
g = pattern.groups
|
|
while not maxsplit or n < maxsplit:
|
|
m = c.search()
|
|
if not m:
|
|
break
|
|
b, e = m.span()
|
|
if b == e:
|
|
if i >= len(text):
|
|
break
|
|
continue
|
|
append(text[i:b])
|
|
if g and b != e:
|
|
extend(list(m.groups()))
|
|
i = e
|
|
n = n + 1
|
|
append(text[i:])
|
|
return s
|
|
|
|
# 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):
|
|
from sre_constants import BRANCH, SUBPATTERN
|
|
self.lexicon = lexicon
|
|
# combine phrases into a compound pattern
|
|
p = []
|
|
s = sre_parse.Pattern()
|
|
for phrase, action in lexicon:
|
|
p.append(sre_parse.SubPattern(s, [
|
|
(SUBPATTERN, (len(p), sre_parse.parse(phrase))),
|
|
]))
|
|
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.match
|
|
i = 0
|
|
while 1:
|
|
m = match(string, i)
|
|
if not m:
|
|
break
|
|
j = m.end()
|
|
if i == j:
|
|
break
|
|
action = self.lexicon[m.lastindex][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:]
|