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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.
33 "*" Matches 0 or more (greedy) repetitions of the preceding RE.
34 Greedy means that it will match as many repetitions as possible.
35 "+" Matches 1 or more (greedy) repetitions of the preceding RE.
36 "?" Matches 0 or 1 (greedy) of the preceding RE.
37 *?,+?,?? Non-greedy versions of the previous three special characters.
38 {m,n} Matches from m to n repetitions of the preceding RE.
39 {m,n}? Non-greedy version of the above.
40 "\\" Either escapes special characters or signals a special sequence.
41 [] Indicates a set of characters.
42 A "^" as the first character indicates a complementing set.
43 "|" A|B, creates an RE that will match either A or B.
44 (...) Matches the RE inside the parentheses.
45 The contents can be retrieved or matched later in the string.
46 (?iLmsux) Set the I, L, M, S, U, or X flag for the RE (see below).
47 (?:...) Non-grouping version of regular parentheses.
48 (?P<name>...) The substring matched by the group is accessible by name.
49 (?P=name) Matches the text matched earlier by the group named name.
50 (?#...) A comment; ignored.
51 (?=...) Matches if ... matches next, but doesn't consume the string.
52 (?!...) Matches if ... doesn't match next.
53
54 The special sequences consist of "\\" and a character from the list
55 below. If the ordinary character is not on the list, then the
56 resulting RE will match the second character.
57 \number Matches the contents of the group of the same number.
58 \A Matches only at the start of the string.
59 \Z Matches only at the end of the string.
60 \b Matches the empty string, but only at the start or end of a word.
61 \B Matches the empty string, but not at the start or end of a word.
62 \d Matches any decimal digit; equivalent to the set [0-9].
63 \D Matches any non-digit character; equivalent to the set [^0-9].
64 \s Matches any whitespace character; equivalent to [ \t\n\r\f\v].
65 \S Matches any non-whitespace character; equiv. to [^ \t\n\r\f\v].
66 \w Matches any alphanumeric character; equivalent to [a-zA-Z0-9_].
67 With LOCALE, it will match the set [0-9_] plus characters defined
68 as letters for the current locale.
69 \W Matches the complement of \w.
70 \\ Matches a literal backslash.
71
72 This module exports the following functions:
73 match Match a regular expression pattern to the beginning of a string.
74 search Search a string for the presence of a pattern.
75 sub Substitute occurrences of a pattern found in a string.
76 subn Same as sub, but also return the number of substitutions made.
77 split Split a string by the occurrences of a pattern.
78 findall Find all occurrences of a pattern in a string.
79 compile Compile a pattern into a RegexObject.
80 purge Clear the regular expression cache.
81 escape Backslash all non-alphanumerics in a string.
82
83 Some of the functions in this module takes flags as optional parameters:
84 I IGNORECASE Perform case-insensitive matching.
85 L LOCALE Make \w, \W, \b, \B, dependent on the current locale.
86 M MULTILINE "^" matches the beginning of lines as well as the string.
87 "$" matches the end of lines as well as the string.
88 S DOTALL "." matches any character at all, including the newline.
89 X VERBOSE Ignore whitespace and comments for nicer looking RE's.
90 U UNICODE Make \w, \W, \b, \B, dependent on the Unicode locale.
91
92 This module also defines an exception 'error'.
93
94 """
95
96 import sys
97 import sre_compile
98 import sre_parse
99
100
101 __all__ = [ "match", "search", "sub", "subn", "split", "findall",
102 "compile", "purge", "template", "escape", "I", "L", "M", "S", "X",
103 "U", "IGNORECASE", "LOCALE", "MULTILINE", "DOTALL", "VERBOSE",
104 "UNICODE", "error" ]
105
106 __version__ = "2.2.1"
107
108
109 I = IGNORECASE = sre_compile.SRE_FLAG_IGNORECASE
110 L = LOCALE = sre_compile.SRE_FLAG_LOCALE
111 U = UNICODE = sre_compile.SRE_FLAG_UNICODE
112 M = MULTILINE = sre_compile.SRE_FLAG_MULTILINE
113 S = DOTALL = sre_compile.SRE_FLAG_DOTALL
114 X = VERBOSE = sre_compile.SRE_FLAG_VERBOSE
115
116
117 T = TEMPLATE = sre_compile.SRE_FLAG_TEMPLATE
118 DEBUG = sre_compile.SRE_FLAG_DEBUG
119
120
121 error = sre_compile.error
122
123
124
125
126 -def match(pattern, string, flags=0):
127 """Try to apply the pattern at the start of the string, returning
128 a match object, or None if no match was found."""
129 return _compile(pattern, flags).match(string)
130
131 -def search(pattern, string, flags=0):
132 """Scan through string looking for a match to the pattern, returning
133 a match object, or None if no match was found."""
134 return _compile(pattern, flags).search(string)
135
136 -def sub(pattern, repl, string, count=0):
137 """Return the string obtained by replacing the leftmost
138 non-overlapping occurrences of the pattern in string by the
139 replacement repl. repl can be either a string or a callable;
140 if a callable, it's passed the match object and must return
141 a replacement string to be used."""
142 return _compile(pattern, 0).sub(repl, string, count)
143
144 -def subn(pattern, repl, string, count=0):
145 """Return a 2-tuple containing (new_string, number).
146 new_string is the string obtained by replacing the leftmost
147 non-overlapping occurrences of the pattern in the source
148 string by the replacement repl. number is the number of
149 substitutions that were made. repl can be either a string or a
150 callable; if a callable, it's passed the match object and must
151 return a replacement string to be used."""
152 return _compile(pattern, 0).subn(repl, string, count)
153
154 -def split(pattern, string, maxsplit=0):
155 """Split the source string by the occurrences of the pattern,
156 returning a list containing the resulting substrings."""
157 return _compile(pattern, 0).split(string, maxsplit)
158
159 -def findall(pattern, string, flags=0):
160 """Return a list of all non-overlapping matches in the string.
161
162 If one or more groups are present in the pattern, return a
163 list of groups; this will be a list of tuples if the pattern
164 has more than one group.
165
166 Empty matches are included in the result."""
167 return _compile(pattern, flags).findall(string)
168
169 if sys.hexversion >= 0x02020000:
170 __all__.append("finditer")
171 def finditer(pattern, string, flags=0):
172 """Return an iterator over all non-overlapping matches in the
173 string. For each match, the iterator returns a match object.
174
175 Empty matches are included in the result."""
176 return _compile(pattern, flags).finditer(string)