1 <!-- ##### SECTION Title ##### -->
2 Perl-compatible regular expressions
4 <!-- ##### SECTION Short_Description ##### -->
5 matches strings against regular expressions
7 <!-- ##### SECTION Long_Description ##### -->
9 The <function>g_regex_*()</function> functions implement regular
10 expression pattern matching using syntax and semantics similar to
11 Perl regular expression.
14 Some functions accept a <parameter>start_position</parameter> argument,
15 setting it differs from just passing over a shortened string and setting
16 #G_REGEX_MATCH_NOTBOL in the case of a pattern that begins with any kind
17 of lookbehind assertion.
18 For example, consider the pattern "\Biss\B" which finds occurrences of "iss"
19 in the middle of words. ("\B" matches only if the current position in the
20 subject is not a word boundary.) When applied to the string "Mississipi"
21 from the fourth byte, namely "issipi", it does not match, because "\B" is
22 always false at the start of the subject, which is deemed to be a word
23 boundary. However, if the entire string is passed , but with
24 <parameter>start_position</parameter> set to 4, it finds the second
25 occurrence of "iss" because it is able to look behind the starting point
26 to discover that it is preceded by a letter.
29 Note that, unless you set the #G_REGEX_RAW flag, all the strings passed
30 to these functions must be encoded in UTF-8. The lengths and the positions
31 inside the strings are in bytes and not in characters, so, for instance,
32 "\xc3\xa0" (i.e. "à") is two bytes long but it is treated as a single
33 character. If you set #G_REGEX_RAW the strings can be non-valid UTF-8
34 strings and a byte is treated as a character, so "\xc3\xa0" is two bytes
35 and two characters long.
38 When matching a pattern, "\n" matches only against a "\n" character in the
39 string, and "\r" matches only a "\r" character. To match any newline sequence
40 use "\R". This particular group matches either the two-character sequence
41 CR + LF ("\r\n"), or one of the single characters LF (linefeed, U+000A, "\n"), VT
42 (vertical tab, U+000B, "\v"), FF (formfeed, U+000C, "\f"), CR (carriage return,
43 U+000D, "\r"), NEL (next line, U+0085), LS (line separator, U+2028), or PS
44 (paragraph separator, U+2029).
47 The behaviour of the dot, circumflex, and dollar metacharacters are affected by
48 newline characters, the default is to recognize any newline character (the same
49 characters recognized by "\R"). This can be changed with #G_REGEX_NEWLINE_CR,
50 #G_REGEX_NEWLINE_LF and #G_REGEX_NEWLINE_CRLF compile options,
51 and with #G_REGEX_MATCH_NEWLINE_ANY, #G_REGEX_MATCH_NEWLINE_CR,
52 #G_REGEX_MATCH_NEWLINE_LF and #G_REGEX_MATCH_NEWLINE_CRLF match options.
53 These settings are also relevant when compiling a pattern if
54 #G_REGEX_EXTENDED is set, and an unescaped "#" outside a character class is
55 encountered. This indicates a comment that lasts until after the next
59 Creating and manipulating the same #GRegex structure from different
60 threads is not a problem as #GRegex does not modify its internal
61 state between creation and destruction, on the other hand #GMatchInfo is
65 The regular expressions low level functionalities are obtained through
66 the excellent <ulink url="http://www.pcre.org/">PCRE</ulink> library
67 written by Philip Hazel.
70 <!-- ##### SECTION See_Also ##### -->
75 <!-- ##### SECTION Stability_Level ##### -->
78 <!-- ##### ENUM GRegexError ##### -->
80 Error codes returned by regular expressions functions.
83 @G_REGEX_ERROR_COMPILE: Compilation of the regular expression failed.
84 @G_REGEX_ERROR_OPTIMIZE: Optimization of the regular expression failed.
85 @G_REGEX_ERROR_REPLACE: Replacement failed due to an ill-formed replacement string.
86 @G_REGEX_ERROR_MATCH: The match process failed.
87 @G_REGEX_ERROR_INTERNAL: Internal error of the regular expression engine. Since 2.16
88 @G_REGEX_ERROR_STRAY_BACKSLASH: "\\" at end of pattern. Since 2.16
89 @G_REGEX_ERROR_MISSING_CONTROL_CHAR: "\\c" at end of pattern. Since 2.16
90 @G_REGEX_ERROR_UNRECOGNIZED_ESCAPE: Unrecognized character follows "\\". Since 2.16
91 @G_REGEX_ERROR_QUANTIFIERS_OUT_OF_ORDER: Numbers out of order in "{}" quantifier. Since 2.16
92 @G_REGEX_ERROR_QUANTIFIER_TOO_BIG: Number too big in "{}" quantifier. Since 2.16
93 @G_REGEX_ERROR_UNTERMINATED_CHARACTER_CLASS: Missing terminating "]" for character class. Since 2.16
94 @G_REGEX_ERROR_INVALID_ESCAPE_IN_CHARACTER_CLASS: Invalid escape sequence in character class. Since 2.16
95 @G_REGEX_ERROR_RANGE_OUT_OF_ORDER: Range out of order in character class. Since 2.16
96 @G_REGEX_ERROR_NOTHING_TO_REPEAT: Nothing to repeat. Since 2.16
97 @G_REGEX_ERROR_UNRECOGNIZED_CHARACTER: Unrecognized character after "(?", "(?<" or "(?P". Since 2.16
98 @G_REGEX_ERROR_POSIX_NAMED_CLASS_OUTSIDE_CLASS: POSIX named classes are supported only within a class. Since 2.16
99 @G_REGEX_ERROR_UNMATCHED_PARENTHESIS: Missing terminating ")" or ")" without opening "(". Since 2.16
100 @G_REGEX_ERROR_INEXISTENT_SUBPATTERN_REFERENCE: Reference to non-existent subpattern. Since 2.16
101 @G_REGEX_ERROR_UNTERMINATED_COMMENT: Missing terminating ")" after comment. Since 2.16
102 @G_REGEX_ERROR_EXPRESSION_TOO_LARGE: Regular expression too large. Since 2.16
103 @G_REGEX_ERROR_MEMORY_ERROR: Failed to get memory. Since 2.16
104 @G_REGEX_ERROR_VARIABLE_LENGTH_LOOKBEHIND: Lookbehind assertion is not fixed length. Since 2.16
105 @G_REGEX_ERROR_MALFORMED_CONDITION: Malformed number or name after "(?(". Since 2.16
106 @G_REGEX_ERROR_TOO_MANY_CONDITIONAL_BRANCHES: Conditional group contains more than two branches. Since 2.16
107 @G_REGEX_ERROR_ASSERTION_EXPECTED: Assertion expected after "(?(". Since 2.16
108 @G_REGEX_ERROR_UNKNOWN_POSIX_CLASS_NAME: Unknown POSIX class name. Since 2.16
109 @G_REGEX_ERROR_POSIX_COLLATING_ELEMENTS_NOT_SUPPORTED: POSIX collating elements are not supported. Since 2.16
110 @G_REGEX_ERROR_HEX_CODE_TOO_LARGE: Character value in "\\x{...}" sequence is too large. Since 2.16
111 @G_REGEX_ERROR_INVALID_CONDITION: Invalid condition "(?(0)". Since 2.16
112 @G_REGEX_ERROR_SINGLE_BYTE_MATCH_IN_LOOKBEHIND: \\C not allowed in lookbehind assertion. Since 2.16
113 @G_REGEX_ERROR_INFINITE_LOOP: Recursive call could loop indefinitely. Since 2.16
114 @G_REGEX_ERROR_MISSING_SUBPATTERN_NAME_TERMINATOR: Missing terminator in subpattern name. Since 2.16
115 @G_REGEX_ERROR_DUPLICATE_SUBPATTERN_NAME: Two named subpatterns have the same name. Since 2.16
116 @G_REGEX_ERROR_MALFORMED_PROPERTY: Malformed "\\P" or "\\p" sequence. Since 2.16
117 @G_REGEX_ERROR_UNKNOWN_PROPERTY: Unknown property name after "\\P" or "\\p". Since 2.16
118 @G_REGEX_ERROR_SUBPATTERN_NAME_TOO_LONG: Subpattern name is too long (maximum 32 characters). Since 2.16
119 @G_REGEX_ERROR_TOO_MANY_SUBPATTERNS: Too many named subpatterns (maximum 10,000). Since 2.16
120 @G_REGEX_ERROR_INVALID_OCTAL_VALUE: Octal value is greater than "\\377". Since 2.16
121 @G_REGEX_ERROR_TOO_MANY_BRANCHES_IN_DEFINE: "DEFINE" group contains more than one branch. Since 2.16
122 @G_REGEX_ERROR_DEFINE_REPETION: Repeating a "DEFINE" group is not allowed. Since 2.16
123 @G_REGEX_ERROR_INCONSISTENT_NEWLINE_OPTIONS: Inconsistent newline options. Since 2.16
124 @G_REGEX_ERROR_MISSING_BACK_REFERENCE: "\\g" is not followed by a braced name or an
125 optionally braced non-zero number. Since 2.16
129 <!-- ##### MACRO G_REGEX_ERROR ##### -->
131 Error domain for regular expressions. Errors in this domain will be from the #GRegexError enumeration. See #GError for information on error domains.
137 <!-- ##### ENUM GRegexCompileFlags ##### -->
139 Flags specifying compile-time options.
142 @G_REGEX_CASELESS: Letters in the pattern match both upper and lower case
143 letters. It be changed within a pattern by a "(?i)" option setting.
144 @G_REGEX_MULTILINE: By default, GRegex treats the strings as consisting
145 of a single line of characters (even if it actually contains newlines).
146 The "start of line" metacharacter ("^") matches only at the start of the
147 string, while the "end of line" metacharacter ("$") matches only at the
148 end of the string, or before a terminating newline (unless
149 #G_REGEX_DOLLAR_ENDONLY is set). When #G_REGEX_MULTILINE is set,
150 the "start of line" and "end of line" constructs match immediately following
151 or immediately before any newline in the string, respectively, as well
152 as at the very start and end. This can be changed within a pattern by a
153 "(?m)" option setting.
154 @G_REGEX_DOTALL: A dot metacharater (".") in the pattern matches all
155 characters, including newlines. Without it, newlines are excluded. This
156 option can be changed within a pattern by a ("?s") option setting.
157 @G_REGEX_EXTENDED: Whitespace data characters in the pattern are
158 totally ignored except when escaped or inside a character class.
159 Whitespace does not include the VT character (code 11). In addition,
160 characters between an unescaped "#" outside a character class and
161 the next newline character, inclusive, are also ignored. This can be
162 changed within a pattern by a "(?x)" option setting.
163 @G_REGEX_ANCHORED: The pattern is forced to be "anchored", that is,
164 it is constrained to match only at the first matching point in the string
165 that is being searched. This effect can also be achieved by appropriate
166 constructs in the pattern itself such as the "^" metacharater.
167 @G_REGEX_DOLLAR_ENDONLY: A dollar metacharacter ("$") in the pattern
168 matches only at the end of the string. Without this option, a dollar also
169 matches immediately before the final character if it is a newline (but
170 not before any other newlines). This option is ignored if
171 #G_REGEX_MULTILINE is set.
172 @G_REGEX_UNGREEDY: Inverts the "greediness" of the
173 quantifiers so that they are not greedy by default, but become greedy
174 if followed by "?". It can also be set by a "(?U)" option setting within
176 @G_REGEX_RAW: Usually strings must be valid UTF-8 strings, using this
177 flag they are considered as a raw sequence of bytes.
178 @G_REGEX_NO_AUTO_CAPTURE: Disables the use of numbered capturing
179 parentheses in the pattern. Any opening parenthesis that is not followed
180 by "?" behaves as if it were followed by "?:" but named parentheses can
181 still be used for capturing (and they acquire numbers in the usual way).
182 @G_REGEX_OPTIMIZE: Optimize the regular expression. If the pattern will
183 be used many times, then it may be worth the effort to optimize it to
184 improve the speed of matches.
185 @G_REGEX_DUPNAMES: Names used to identify capturing subpatterns need not
186 be unique. This can be helpful for certain types of pattern when it is known
187 that only one instance of the named subpattern can ever be matched.
188 @G_REGEX_NEWLINE_CR: Usually any newline character is recognized, if this
189 option is set, the only recognized newline character is '\r'.
190 @G_REGEX_NEWLINE_LF: Usually any newline character is recognized, if this
191 option is set, the only recognized newline character is '\n'.
192 @G_REGEX_NEWLINE_CRLF: Usually any newline character is recognized, if this
193 option is set, the only recognized newline character sequence is '\r\n'.
196 <!-- ##### ENUM GRegexMatchFlags ##### -->
198 Flags specifying match-time options.
201 @G_REGEX_MATCH_ANCHORED: The pattern is forced to be "anchored", that is,
202 it is constrained to match only at the first matching point in the string
203 that is being searched. This effect can also be achieved by appropriate
204 constructs in the pattern itself such as the "^" metacharater.
205 @G_REGEX_MATCH_NOTBOL: Specifies that first character of the string is
206 not the beginning of a line, so the circumflex metacharacter should not
207 match before it. Setting this without G_REGEX_MULTILINE (at compile time)
208 causes circumflex never to match. This option affects only the behaviour of
209 the circumflex metacharacter, it does not affect "\A".
210 @G_REGEX_MATCH_NOTEOL: Specifies that the end of the subject string is
211 not the end of a line, so the dollar metacharacter should not match it nor
212 (except in multiline mode) a newline immediately before it. Setting this
213 without G_REGEX_MULTILINE (at compile time) causes dollar never to match.
214 This option affects only the behaviour of the dollar metacharacter, it does
215 not affect "\Z" or "\z".
216 @G_REGEX_MATCH_NOTEMPTY: An empty string is not considered to be a valid
217 match if this option is set. If there are alternatives in the pattern, they
218 are tried. If all the alternatives match the empty string, the entire match
219 fails. For example, if the pattern "a?b?" is applied to a string not beginning
220 with "a" or "b", it matches the empty string at the start of the string.
221 With this flag set, this match is not valid, so GRegex searches further
222 into the string for occurrences of "a" or "b".
223 @G_REGEX_MATCH_PARTIAL: Turns on the partial matching feature, for more
224 documentation on partial matching see g_regex_is_partial_match().
225 @G_REGEX_MATCH_NEWLINE_CR: Overrides the newline definition set when creating
226 a new #GRegex, setting the '\r' character as line terminator.
227 @G_REGEX_MATCH_NEWLINE_LF: Overrides the newline definition set when creating
228 a new #GRegex, setting the '\n' character as line terminator.
229 @G_REGEX_MATCH_NEWLINE_CRLF: Overrides the newline definition set when creating
230 a new #GRegex, setting the '\r\n' characters as line terminator.
231 @G_REGEX_MATCH_NEWLINE_ANY: Overrides the newline definition set when creating
232 a new #GRegex, any newline character or character sequence is recognized.
235 <!-- ##### STRUCT GRegex ##### -->
237 A GRegex is the "compiled" form of a regular expression pattern. This
238 structure is opaque and its fields cannot be accessed directly.
243 <!-- ##### USER_FUNCTION GRegexEvalCallback ##### -->
245 Specifies the type of the function passed to g_regex_replace_eval().
246 It is called for each occurance of the pattern in the string passed
247 to g_regex_replace_eval(), and it should append the replacement to
251 @match_info: the #GMatchInfo generated by the match.
252 Use g_match_info_get_regex() and g_match_info_get_string() if you
253 need the #GRegex or the matched string.
254 @result: a #GString containing the new string
255 @user_data: user data passed to g_regex_replace_eval()
256 @Returns: %FALSE to continue the replacement process, %TRUE to stop it
260 <!-- ##### FUNCTION g_regex_new ##### -->
272 <!-- ##### FUNCTION g_regex_ref ##### -->
281 <!-- ##### FUNCTION g_regex_unref ##### -->
289 <!-- ##### FUNCTION g_regex_get_pattern ##### -->
298 <!-- ##### FUNCTION g_regex_get_max_backref ##### -->
307 <!-- ##### FUNCTION g_regex_get_capture_count ##### -->
316 <!-- ##### FUNCTION g_regex_get_string_number ##### -->
326 <!-- ##### FUNCTION g_regex_escape_string ##### -->
336 <!-- ##### FUNCTION g_regex_match_simple ##### -->
348 <!-- ##### FUNCTION g_regex_match ##### -->
360 <!-- ##### FUNCTION g_regex_match_full ##### -->
375 <!-- ##### FUNCTION g_regex_match_all ##### -->
387 <!-- ##### FUNCTION g_regex_match_all_full ##### -->
402 <!-- ##### FUNCTION g_regex_split_simple ##### -->
414 <!-- ##### FUNCTION g_regex_split ##### -->
425 <!-- ##### FUNCTION g_regex_split_full ##### -->
440 <!-- ##### FUNCTION g_regex_replace ##### -->
455 <!-- ##### FUNCTION g_regex_replace_literal ##### -->
470 <!-- ##### FUNCTION g_regex_replace_eval ##### -->
486 <!-- ##### FUNCTION g_regex_check_replacement ##### -->
497 <!-- ##### STRUCT GMatchInfo ##### -->
499 #GMatchInfo is used to retrieve information about the regular expression match
501 This structure is opaque and its fields cannot be accessed directly.
506 <!-- ##### FUNCTION g_match_info_get_regex ##### -->
515 <!-- ##### FUNCTION g_match_info_get_string ##### -->
524 <!-- ##### FUNCTION g_match_info_free ##### -->
532 <!-- ##### FUNCTION g_match_info_matches ##### -->
541 <!-- ##### FUNCTION g_match_info_next ##### -->
551 <!-- ##### FUNCTION g_match_info_get_match_count ##### -->
560 <!-- ##### FUNCTION g_match_info_is_partial_match ##### -->
569 <!-- ##### FUNCTION g_match_info_expand_references ##### -->
580 <!-- ##### FUNCTION g_match_info_fetch ##### -->
590 <!-- ##### FUNCTION g_match_info_fetch_pos ##### -->
602 <!-- ##### FUNCTION g_match_info_fetch_named ##### -->
612 <!-- ##### FUNCTION g_match_info_fetch_named_pos ##### -->
624 <!-- ##### FUNCTION g_match_info_fetch_all ##### -->