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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
108
109 __all__ = [ "match", "search", "sub", "subn", "split", "findall",
110 "compile", "purge", "template", "escape", "I", "L", "M", "S", "X",
111 "U", "IGNORECASE", "LOCALE", "MULTILINE", "DOTALL", "VERBOSE",
112 "UNICODE", "error" ]
113
114 __version__ = "2.2.1"
115
116
117 I = IGNORECASE = sre_compile.SRE_FLAG_IGNORECASE
118 L = LOCALE = sre_compile.SRE_FLAG_LOCALE
119 U = UNICODE = sre_compile.SRE_FLAG_UNICODE
120 M = MULTILINE = sre_compile.SRE_FLAG_MULTILINE
121 S = DOTALL = sre_compile.SRE_FLAG_DOTALL
122 X = VERBOSE = sre_compile.SRE_FLAG_VERBOSE
123
124
125 T = TEMPLATE = sre_compile.SRE_FLAG_TEMPLATE
126 DEBUG = sre_compile.SRE_FLAG_DEBUG
127
128
129 error = sre_compile.error
130
131
132
133
134 -def match(pattern, string, flags=0):
135 """Try to apply the pattern at the start of the string, returning
136 a match object, or None if no match was found."""
137 return _compile(pattern, flags).match(string)
138
139 -def search(pattern, string, flags=0):
140 """Scan through string looking for a match to the pattern, returning
141 a match object, or None if no match was found."""
142 return _compile(pattern, flags).search(string)
143
144 -def sub(pattern, repl, string, count=0):
145 """Return the string obtained by replacing the leftmost
146 non-overlapping occurrences of the pattern in string by the
147 replacement repl. repl can be either a string or a callable;
148 if a string, backslash escapes in it are processed. If it is
149 a callable, it's passed the match object and must return
150 a replacement string to be used."""
151 return _compile(pattern, 0).sub(repl, string, count)
152
153 -def subn(pattern, repl, string, count=0):
154 """Return a 2-tuple containing (new_string, number).
155 new_string is the string obtained by replacing the leftmost
156 non-overlapping occurrences of the pattern in the source
157 string by the replacement repl. number is the number of
158 substitutions that were made. repl can be either a string or a
159 callable; if a string, backslash escapes in it are processed.
160 If it is a callable, it's passed the match object and must
161 return a replacement string to be used."""
162 return _compile(pattern, 0).subn(repl, string, count)
163
164 -def split(pattern, string, maxsplit=0):
165 """Split the source string by the occurrences of the pattern,
166 returning a list containing the resulting substrings."""
167 return _compile(pattern, 0).split(string, maxsplit)
168
169 -def findall(pattern, string, flags=0):
170 """Return a list of all non-overlapping matches in the string.
171
172 If one or more groups are present in the pattern, return a
173 list of groups; this will be a list of tuples if the pattern
174 has more than one group.
175
176 Empty matches are included in the result."""
177 return _compile(pattern, flags).findall(string)
178
179 if sys.hexversion >= 0x02020000:
180 __all__.append("finditer")
181 - def finditer(pattern, string, flags=0):
182 """Return an iterator over all non-overlapping matches in the
183 string. For each match, the iterator returns a match object.
184
185 Empty matches are included in the result."""
186 return _compile(pattern, flags).finditer(string)
187
189 "Compile a regular expression pattern, returning a pattern object."
190 return _compile(pattern, flags)
191
196
198 "Compile a template pattern, returning a pattern object"
199 return _compile(pattern, flags|T)
200
201 _alphanum = {}
202 for c in 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ01234567890':
203 _alphanum[c] = 1
204 del c
205
207 "Escape all non-alphanumeric characters in pattern."
208 s = list(pattern)
209 alphanum = _alphanum
210 for i in range(len(pattern)):
211 c = pattern[i]
212 if c not in alphanum:
213 if c == "\000":
214 s[i] = "\\000"
215 else:
216 s[i] = "\\" + c
217 return pattern[:0].join(s)
218
219
220
221
222 _cache = {}
223 _cache_repl = {}
224
225 _pattern_type = type(sre_compile.compile("", 0))
226
227 _MAXCACHE = 100
228
230
231 cachekey = (type(key[0]),) + key
232 p = _cache.get(cachekey)
233 if p is not None:
234 return p
235 pattern, flags = key
236 if isinstance(pattern, _pattern_type):
237 if flags:
238 raise ValueError('Cannot process flags argument with a compiled pattern')
239 return pattern
240 if not sre_compile.isstring(pattern):
241 raise TypeError, "first argument must be string or compiled pattern"
242 try:
243 p = sre_compile.compile(pattern, flags)
244 except error, v:
245 raise error, v
246 if len(_cache) >= _MAXCACHE:
247 _cache.clear()
248 _cache[cachekey] = p
249 return p
250
265
266 -def _expand(pattern, match, template):
267
268 template = sre_parse.parse_template(template, pattern)
269 return sre_parse.expand_template(template, match)
270
271 -def _subx(pattern, template):
272
273 template = _compile_repl(template, pattern)
274 if not template[0] and len(template[1]) == 1:
275
276 return template[1][0]
277 def filter(match, template=template):
278 return sre_parse.expand_template(template, match)
279 return filter
280
281
282
283 import copy_reg
284
286 return _compile, (p.pattern, p.flags)
287
288 copy_reg.pickle(_pattern_type, _pickle, _compile)
289
290
291
292
295 from sre_constants import BRANCH, SUBPATTERN
296 self.lexicon = lexicon
297
298 p = []
299 s = sre_parse.Pattern()
300 s.flags = flags
301 for phrase, action in lexicon:
302 p.append(sre_parse.SubPattern(s, [
303 (SUBPATTERN, (len(p)+1, sre_parse.parse(phrase, flags))),
304 ]))
305 s.groups = len(p)+1
306 p = sre_parse.SubPattern(s, [(BRANCH, (None, p))])
307 self.scanner = sre_compile.compile(p)
308 - def scan(self, string):
309 result = []
310 append = result.append
311 match = self.scanner.scanner(string).match
312 i = 0
313 while 1:
314 m = match()
315 if not m:
316 break
317 j = m.end()
318 if i == j:
319 break
320 action = self.lexicon[m.lastindex-1][1]
321 if hasattr(action, '__call__'):
322 self.match = m
323 action = action(self, m.group())
324 if action is not None:
325 append(action)
326 i = j
327 return result, string[i:]