Struct

GLibRegex

Description [src]

struct GRegex {
  /* No available fields */
}

The g_regex_*() functions implement regular expression pattern matching using syntax and semantics similar to Perl regular expression.

Some functions accept a start_position argument, setting it differs from just passing over a shortened string and setting #G_REGEX_MATCH_NOTBOL in the case of a pattern that begins with any kind of lookbehind assertion. For example, consider the pattern “\Biss\B” which finds occurrences of “iss” in the middle of words. (“\B” matches only if the current position in the subject is not a word boundary.) When applied to the string “Mississipi” from the fourth byte, namely “issipi”, it does not match, because “\B” is always false at the start of the subject, which is deemed to be a word boundary. However, if the entire string is passed , but with start_position set to 4, it finds the second occurrence of “iss” because it is able to look behind the starting point to discover that it is preceded by a letter.

Note that, unless you set the #G_REGEX_RAW flag, all the strings passed to these functions must be encoded in UTF-8. The lengths and the positions inside the strings are in bytes and not in characters, so, for instance, “\xc3\xa0” (i.e. “à”) is two bytes long but it is treated as a single character. If you set #G_REGEX_RAW the strings can be non-valid UTF-8 strings and a byte is treated as a character, so “\xc3\xa0” is two bytes and two characters long.

When matching a pattern, “\n” matches only against a “\n” character in the string, and “\r” matches only a “\r” character. To match any newline sequence use “\R”. This particular group matches either the two-character sequence CR + LF (“\r\n”), or one of the single characters LF (linefeed, U+000A, “\n”), VT vertical tab, U+000B, “\v”), FF (formfeed, U+000C, “\f”), CR (carriage return, U+000D, “\r”), NEL (next line, U+0085), LS (line separator, U+2028), or PS (paragraph separator, U+2029).

The behaviour of the dot, circumflex, and dollar metacharacters are affected by newline characters, the default is to recognize any newline character (the same characters recognized by “\R”). This can be changed with #G_REGEX_NEWLINE_CR, #G_REGEX_NEWLINE_LF and #G_REGEX_NEWLINE_CRLF compile options, and with #G_REGEX_MATCH_NEWLINE_ANY,

G_REGEX_MATCH_NEWLINE_CR, #G_REGEX_MATCH_NEWLINE_LF and

G_REGEX_MATCH_NEWLINE_CRLF match options. These settings are also

relevant when compiling a pattern if #G_REGEX_EXTENDED is set, and an unescaped “#” outside a character class is encountered. This indicates a comment that lasts until after the next newline.

When setting the G_REGEX_JAVASCRIPT_COMPAT flag, pattern syntax and pattern matching is changed to be compatible with the way that regular expressions work in JavaScript. More precisely, a lonely ‘]’ character in the pattern is a syntax error; the ‘\x’ escape only allows 0 to 2 hexadecimal digits, and you must use the ‘\u’ escape sequence with 4 hex digits to specify a unicode codepoint instead of ‘\x’ or ‘x{….}’. If ‘\x’ or ‘\u’ are not followed by the specified number of hex digits, they match ‘x’ and ‘u’ literally; also ‘\U’ always matches ‘U’ instead of being an error in the pattern. Finally, pattern matching is modified so that back references to an unset subpattern group produces a match with the empty string instead of an error. See pcreapi(3) for more information.

Creating and manipulating the same GRegex structure from different threads is not a problem as GRegex does not modify its internal state between creation and destruction, on the other hand GMatchInfo is not threadsafe.

The regular expressions low-level functionalities are obtained through the excellent PCRE library written by Philip Hazel.

Available since:2.14

Constructors

g_regex_new

Compiles the regular expression to an internal form, and does the initial setup of the GRegex structure.

Available since: 2.14

Functions

g_regex_check_replacement

Checks whether replacement is a valid replacement string (see g_regex_replace()), i.e. that all escape sequences in it are valid.

Available since: 2.14

g_regex_error_quark
No description available.
g_regex_escape_nul

Escapes the nul characters in string to “\x00”. It can be used to compile a regex with embedded nul characters.

Available since: 2.30

g_regex_escape_string

Escapes the special characters used for regular expressions in string, for instance “a.b*c” becomes “a.b*c”. This function is useful to dynamically generate regular expressions.

Available since: 2.14

g_regex_match_simple

Scans for a match in string for pattern.

Available since: 2.14

g_regex_split_simple

Breaks the string on the pattern, and returns an array of the tokens. If the pattern contains capturing parentheses, then the text for each of the substrings will also be returned. If the pattern does not match anywhere in the string, then the whole string is returned as the first token.

Available since: 2.14

Instance methods

g_regex_get_capture_count

Returns the number of capturing subpatterns in the pattern.

Available since: 2.14

g_regex_get_compile_flags

Returns the compile options that regex was created with.

Available since: 2.26

g_regex_get_has_cr_or_lf

Checks whether the pattern contains explicit CR or LF references.

Available since: 2.34

g_regex_get_match_flags

Returns the match options that regex was created with.

Available since: 2.26

g_regex_get_max_backref

Returns the number of the highest back reference in the pattern, or 0 if the pattern does not contain back references.

Available since: 2.14

g_regex_get_max_lookbehind

Gets the number of characters in the longest lookbehind assertion in the pattern. This information is useful when doing multi-segment matching using the partial matching facilities.

Available since: 2.38

g_regex_get_pattern

Gets the pattern string associated with regex, i.e. a copy of the string passed to g_regex_new().

Available since: 2.14

g_regex_get_string_number

Retrieves the number of the subexpression named name.

Available since: 2.14

g_regex_match

Scans for a match in string for the pattern in regex. The match_options are combined with the match options specified when the regex structure was created, letting you have more flexibility in reusing GRegex structures.

Available since: 2.14

g_regex_match_all

Using the standard algorithm for regular expression matching only the longest match in the string is retrieved. This function uses a different algorithm so it can retrieve all the possible matches. For more documentation see g_regex_match_all_full().

Available since: 2.14

g_regex_match_all_full

Using the standard algorithm for regular expression matching only the longest match in the string is retrieved, it is not possible to obtain all the available matches. For instance matching “ ” against the pattern “<.*>” you get “ “.

Available since: 2.14

g_regex_match_full

Scans for a match in string for the pattern in regex. The match_options are combined with the match options specified when the regex structure was created, letting you have more flexibility in reusing GRegex structures.

Available since: 2.14

g_regex_ref

Increases reference count of regex by 1.

Available since: 2.14

g_regex_replace

Replaces all occurrences of the pattern in regex with the replacement text. Backreferences of the form ‘\number’ or ‘\g‘ in the replacement text are interpolated by the number-th captured subexpression of the match, ‘\g‘ refers to the captured subexpression with the given name. ‘\0’ refers to the complete match, but ‘\0’ followed by a number is the octal representation of a character. To include a literal ‘' in the replacement, write ‘\’.

Available since: 2.14

g_regex_replace_eval

Replaces occurrences of the pattern in regex with the output of eval for that occurrence.

Available since: 2.14

g_regex_replace_literal

Replaces all occurrences of the pattern in regex with the replacement text. replacement is replaced literally, to include backreferences use g_regex_replace().

Available since: 2.14

g_regex_split

Breaks the string on the pattern, and returns an array of the tokens. If the pattern contains capturing parentheses, then the text for each of the substrings will also be returned. If the pattern does not match anywhere in the string, then the whole string is returned as the first token.

Available since: 2.14

g_regex_split_full

Breaks the string on the pattern, and returns an array of the tokens. If the pattern contains capturing parentheses, then the text for each of the substrings will also be returned. If the pattern does not match anywhere in the string, then the whole string is returned as the first token.

Available since: 2.14

g_regex_unref

Decreases reference count of regex by 1. When reference count drops to zero, it frees all the memory associated with the regex structure.

Available since: 2.14