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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 callable, it's passed the match object and must return
149 a replacement string to be used."""
150 return _compile(pattern, 0).sub(repl, string, count)
151
152 -def subn(pattern, repl, string, count=0):
153 """Return a 2-tuple containing (new_string, number).
154 new_string is the string obtained by replacing the leftmost
155 non-overlapping occurrences of the pattern in the source
156 string by the replacement repl. number is the number of
157 substitutions that were made. repl can be either a string or a
158 callable; if a callable, it's passed the match object and must
159 return a replacement string to be used."""
160 return _compile(pattern, 0).subn(repl, string, count)
161
162 -def split(pattern, string, maxsplit=0):
163 """Split the source string by the occurrences of the pattern,
164 returning a list containing the resulting substrings."""
165 return _compile(pattern, 0).split(string, maxsplit)
166
167 -def findall(pattern, string, flags=0):
168 """Return a list of all non-overlapping matches in the string.
169
170 If one or more groups are present in the pattern, return a
171 list of groups; this will be a list of tuples if the pattern
172 has more than one group.
173
174 Empty matches are included in the result."""
175 return _compile(pattern, flags).findall(string)
176
177 if sys.hexversion >= 0x02020000:
178 __all__.append("finditer")
179 - def finditer(pattern, string, flags=0):
180 """Return an iterator over all non-overlapping matches in the
181 string. For each match, the iterator returns a match object.
182
183 Empty matches are included in the result."""
184 return _compile(pattern, flags).finditer(string)
185
187 "Compile a regular expression pattern, returning a pattern object."
188 return _compile(pattern, flags)
189
194
196 "Compile a template pattern, returning a pattern object"
197 return _compile(pattern, flags|T)
198
199 _alphanum = {}
200 for c in 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ01234567890':
201 _alphanum[c] = 1
202 del c
203
205 "Escape all non-alphanumeric characters in pattern."
206 s = list(pattern)
207 alphanum = _alphanum
208 for i in range(len(pattern)):
209 c = pattern[i]
210 if c not in alphanum:
211 if c == "\000":
212 s[i] = "\\000"
213 else:
214 s[i] = "\\" + c
215 return pattern[:0].join(s)
216
217
218
219
220 _cache = {}
221 _cache_repl = {}
222
223 _pattern_type = type(sre_compile.compile("", 0))
224
225 _MAXCACHE = 100
226
228
229 cachekey = (type(key[0]),) + key
230 p = _cache.get(cachekey)
231 if p is not None:
232 return p
233 pattern, flags = key
234 if isinstance(pattern, _pattern_type):
235 return pattern
236 if not sre_compile.isstring(pattern):
237 raise TypeError, "first argument must be string or compiled pattern"
238 try:
239 p = sre_compile.compile(pattern, flags)
240 except error, v:
241 raise error, v
242 if len(_cache) >= _MAXCACHE:
243 _cache.clear()
244 _cache[cachekey] = p
245 return p
246
261
262 -def _expand(pattern, match, template):
263
264 template = sre_parse.parse_template(template, pattern)
265 return sre_parse.expand_template(template, match)
266
267 -def _subx(pattern, template):
268
269 template = _compile_repl(template, pattern)
270 if not template[0] and len(template[1]) == 1:
271
272 return template[1][0]
273 def filter(match, template=template):
274 return sre_parse.expand_template(template, match)
275 return filter
276
277
278
279 import copy_reg
280
282 return _compile, (p.pattern, p.flags)
283
284 copy_reg.pickle(_pattern_type, _pickle, _compile)
285
286
287
288
291 from sre_constants import BRANCH, SUBPATTERN
292 self.lexicon = lexicon
293
294 p = []
295 s = sre_parse.Pattern()
296 s.flags = flags
297 for phrase, action in lexicon:
298 p.append(sre_parse.SubPattern(s, [
299 (SUBPATTERN, (len(p)+1, sre_parse.parse(phrase, flags))),
300 ]))
301 s.groups = len(p)+1
302 p = sre_parse.SubPattern(s, [(BRANCH, (None, p))])
303 self.scanner = sre_compile.compile(p)
304 - def scan(self, string):
305 result = []
306 append = result.append
307 match = self.scanner.scanner(string).match
308 i = 0
309 while 1:
310 m = match()
311 if not m:
312 break
313 j = m.end()
314 if i == j:
315 break
316 action = self.lexicon[m.lastindex-1][1]
317 if callable(action):
318 self.match = m
319 action = action(self, m.group())
320 if action is not None:
321 append(action)
322 i = j
323 return result, string[i:]