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17 r"""Support for regular expressions (RE).
18
19 This module provides regular expression matching operations similar to
20 those found in Perl. It supports both 8-bit and Unicode strings; both
21 the pattern and the strings being processed can contain null bytes and
22 characters outside the US ASCII range.
23
24 Regular expressions can contain both special and ordinary characters.
25 Most ordinary characters, like "A", "a", or "0", are the simplest
26 regular expressions; they simply match themselves. You can
27 concatenate ordinary characters, so last matches the string 'last'.
28
29 The special characters are:
30 "." Matches any character except a newline.
31 "^" Matches the start of the string.
32 "$" Matches the end of the string or just before the newline at
33 the end of the string.
34 "*" Matches 0 or more (greedy) repetitions of the preceding RE.
35 Greedy means that it will match as many repetitions as possible.
36 "+" Matches 1 or more (greedy) repetitions of the preceding RE.
37 "?" Matches 0 or 1 (greedy) of the preceding RE.
38 *?,+?,?? Non-greedy versions of the previous three special characters.
39 {m,n} Matches from m to n repetitions of the preceding RE.
40 {m,n}? Non-greedy version of the above.
41 "\\" Either escapes special characters or signals a special sequence.
42 [] Indicates a set of characters.
43 A "^" as the first character indicates a complementing set.
44 "|" A|B, creates an RE that will match either A or B.
45 (...) Matches the RE inside the parentheses.
46 The contents can be retrieved or matched later in the string.
47 (?iLmsux) Set the I, L, M, S, U, or X flag for the RE (see below).
48 (?:...) Non-grouping version of regular parentheses.
49 (?P<name>...) The substring matched by the group is accessible by name.
50 (?P=name) Matches the text matched earlier by the group named name.
51 (?#...) A comment; ignored.
52 (?=...) Matches if ... matches next, but doesn't consume the string.
53 (?!...) Matches if ... doesn't match next.
54 (?<=...) Matches if preceded by ... (must be fixed length).
55 (?<!...) Matches if not preceded by ... (must be fixed length).
56 (?(id/name)yes|no) Matches yes pattern if the group with id/name matched,
57 the (optional) no pattern otherwise.
58
59 The special sequences consist of "\\" and a character from the list
60 below. If the ordinary character is not on the list, then the
61 resulting RE will match the second character.
62 \number Matches the contents of the group of the same number.
63 \A Matches only at the start of the string.
64 \Z Matches only at the end of the string.
65 \b Matches the empty string, but only at the start or end of a word.
66 \B Matches the empty string, but not at the start or end of a word.
67 \d Matches any decimal digit; equivalent to the set [0-9].
68 \D Matches any non-digit character; equivalent to the set [^0-9].
69 \s Matches any whitespace character; equivalent to [ \t\n\r\f\v].
70 \S Matches any non-whitespace character; equiv. to [^ \t\n\r\f\v].
71 \w Matches any alphanumeric character; equivalent to [a-zA-Z0-9_].
72 With LOCALE, it will match the set [0-9_] plus characters defined
73 as letters for the current locale.
74 \W Matches the complement of \w.
75 \\ Matches a literal backslash.
76
77 This module exports the following functions:
78 match Match a regular expression pattern to the beginning of a string.
79 search Search a string for the presence of a pattern.
80 sub Substitute occurrences of a pattern found in a string.
81 subn Same as sub, but also return the number of substitutions made.
82 split Split a string by the occurrences of a pattern.
83 findall Find all occurrences of a pattern in a string.
84 finditer Return an iterator yielding a match object for each match.
85 compile Compile a pattern into a RegexObject.
86 purge Clear the regular expression cache.
87 escape Backslash all non-alphanumerics in a string.
88
89 Some of the functions in this module takes flags as optional parameters:
90 I IGNORECASE Perform case-insensitive matching.
91 L LOCALE Make \w, \W, \b, \B, dependent on the current locale.
92 M MULTILINE "^" matches the beginning of lines (after a newline)
93 as well as the string.
94 "$" matches the end of lines (before a newline) as well
95 as the end of the string.
96 S DOTALL "." matches any character at all, including the newline.
97 X VERBOSE Ignore whitespace and comments for nicer looking RE's.
98 U UNICODE Make \w, \W, \b, \B, dependent on the Unicode locale.
99
100 This module also defines an exception 'error'.
101
102 """
103
104 import sys
105 import sre_compile
106 import sre_parse
107 try:
108 import _locale
109 except ImportError:
110 _locale = None
111
112
113 __all__ = [ "match", "search", "sub", "subn", "split", "findall",
114 "compile", "purge", "template", "escape", "I", "L", "M", "S", "X",
115 "U", "IGNORECASE", "LOCALE", "MULTILINE", "DOTALL", "VERBOSE",
116 "UNICODE", "error" ]
117
118 __version__ = "2.2.1"
119
120
121 I = IGNORECASE = sre_compile.SRE_FLAG_IGNORECASE
122 L = LOCALE = sre_compile.SRE_FLAG_LOCALE
123 U = UNICODE = sre_compile.SRE_FLAG_UNICODE
124 M = MULTILINE = sre_compile.SRE_FLAG_MULTILINE
125 S = DOTALL = sre_compile.SRE_FLAG_DOTALL
126 X = VERBOSE = sre_compile.SRE_FLAG_VERBOSE
127
128
129 T = TEMPLATE = sre_compile.SRE_FLAG_TEMPLATE
130 DEBUG = sre_compile.SRE_FLAG_DEBUG
131
132
133 error = sre_compile.error
134
135
136
137
138 -def match(pattern, string, flags=0):
139 """Try to apply the pattern at the start of the string, returning
140 a match object, or None if no match was found."""
141 return _compile(pattern, flags).match(string)
142
143 -def search(pattern, string, flags=0):
144 """Scan through string looking for a match to the pattern, returning
145 a match object, or None if no match was found."""
146 return _compile(pattern, flags).search(string)
147
148 -def sub(pattern, repl, string, count=0, flags=0):
149 """Return the string obtained by replacing the leftmost
150 non-overlapping occurrences of the pattern in string by the
151 replacement repl. repl can be either a string or a callable;
152 if a string, backslash escapes in it are processed. If it is
153 a callable, it's passed the match object and must return
154 a replacement string to be used."""
155 return _compile(pattern, flags).sub(repl, string, count)
156
157 -def subn(pattern, repl, string, count=0, flags=0):
158 """Return a 2-tuple containing (new_string, number).
159 new_string is the string obtained by replacing the leftmost
160 non-overlapping occurrences of the pattern in the source
161 string by the replacement repl. number is the number of
162 substitutions that were made. repl can be either a string or a
163 callable; if a string, backslash escapes in it are processed.
164 If it is a callable, it's passed the match object and must
165 return a replacement string to be used."""
166 return _compile(pattern, flags).subn(repl, string, count)
167
168 -def split(pattern, string, maxsplit=0, flags=0):
169 """Split the source string by the occurrences of the pattern,
170 returning a list containing the resulting substrings."""
171 return _compile(pattern, flags).split(string, maxsplit)
172
173 -def findall(pattern, string, flags=0):
174 """Return a list of all non-overlapping matches in the string.
175
176 If one or more groups are present in the pattern, return a
177 list of groups; this will be a list of tuples if the pattern
178 has more than one group.
179
180 Empty matches are included in the result."""
181 return _compile(pattern, flags).findall(string)
182
183 if sys.hexversion >= 0x02020000:
184 __all__.append("finditer")
185 - def finditer(pattern, string, flags=0):
186 """Return an iterator over all non-overlapping matches in the
187 string. For each match, the iterator returns a match object.
188
189 Empty matches are included in the result."""
190 return _compile(pattern, flags).finditer(string)
191
193 "Compile a regular expression pattern, returning a pattern object."
194 return _compile(pattern, flags)
195
200
202 "Compile a template pattern, returning a pattern object"
203 return _compile(pattern, flags|T)
204
205 _alphanum = frozenset(
206 "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789")
207
209 "Escape all non-alphanumeric characters in pattern."
210 s = list(pattern)
211 alphanum = _alphanum
212 for i, c in enumerate(pattern):
213 if c not in alphanum:
214 if c == "\000":
215 s[i] = "\\000"
216 else:
217 s[i] = "\\" + c
218 return pattern[:0].join(s)
219
220
221
222
223 _cache = {}
224 _cache_repl = {}
225
226 _pattern_type = type(sre_compile.compile("", 0))
227
228 _MAXCACHE = 100
229
231
232 pattern, flags = key
233 bypass_cache = flags & DEBUG
234 if not bypass_cache:
235 cachekey = (type(key[0]),) + key
236 try:
237 p, loc = _cache[cachekey]
238 if loc is None or loc == _locale.setlocale(_locale.LC_CTYPE):
239 return p
240 except KeyError:
241 pass
242 if isinstance(pattern, _pattern_type):
243 if flags:
244 raise ValueError('Cannot process flags argument with a compiled pattern')
245 return pattern
246 if not sre_compile.isstring(pattern):
247 raise TypeError, "first argument must be string or compiled pattern"
248 try:
249 p = sre_compile.compile(pattern, flags)
250 except error, v:
251 raise error, v
252 if not bypass_cache:
253 if len(_cache) >= _MAXCACHE:
254 _cache.clear()
255 if p.flags & LOCALE:
256 if not _locale:
257 return p
258 loc = _locale.setlocale(_locale.LC_CTYPE)
259 else:
260 loc = None
261 _cache[cachekey] = p, loc
262 return p
263
278
279 -def _expand(pattern, match, template):
280
281 template = sre_parse.parse_template(template, pattern)
282 return sre_parse.expand_template(template, match)
283
284 -def _subx(pattern, template):
285
286 template = _compile_repl(template, pattern)
287 if not template[0] and len(template[1]) == 1:
288
289 return template[1][0]
290 def filter(match, template=template):
291 return sre_parse.expand_template(template, match)
292 return filter
293
294
295
296 import copy_reg
297
299 return _compile, (p.pattern, p.flags)
300
301 copy_reg.pickle(_pattern_type, _pickle, _compile)
302
303
304
305
308 from sre_constants import BRANCH, SUBPATTERN
309 self.lexicon = lexicon
310
311 p = []
312 s = sre_parse.Pattern()
313 s.flags = flags
314 for phrase, action in lexicon:
315 p.append(sre_parse.SubPattern(s, [
316 (SUBPATTERN, (len(p)+1, sre_parse.parse(phrase, flags))),
317 ]))
318 s.groups = len(p)+1
319 p = sre_parse.SubPattern(s, [(BRANCH, (None, p))])
320 self.scanner = sre_compile.compile(p)
321 - def scan(self, string):