Perl-compatible regular expressions

Perl-compatible regular expressions — matches strings against regular expressions.

Synopsis


#include <glib.h>


enum        GRegexError;
#define     G_REGEX_ERROR
enum        GRegexCompileFlags;
enum        GRegexMatchFlags;
            GRegex;
gboolean    (*GRegexEvalCallback)           (const GRegex *,
                                             const gchar *,
                                             GString *,
                                             gpointer );
GRegex*     g_regex_new                     (const gchar *pattern,
                                             GRegexCompileFlags compile_options,
                                             GRegexMatchFlags match_options,
                                             GError **error);
void        g_regex_free                    (GRegex *regex);
gboolean    g_regex_optimize                (GRegex *regex,
                                             GError **error);
GRegex*     g_regex_copy                    (const GRegex *regex);
const gchar* g_regex_get_pattern            (const GRegex *regex);
void        g_regex_clear                   (GRegex *regex);
gboolean    g_regex_match_simple            (const gchar *pattern,
                                             const gchar *string,
                                             GRegexCompileFlags compile_options,
                                             GRegexMatchFlags match_options);
gboolean    g_regex_match                   (GRegex *regex,
                                             const gchar *string,
                                             GRegexMatchFlags match_options);
gboolean    g_regex_match_full              (GRegex *regex,
                                             const gchar *string,
                                             gssize string_len,
                                             gint start_position,
                                             GRegexMatchFlags match_options,
                                             GError **error);
gboolean    g_regex_match_next              (GRegex *regex,
                                             const gchar *string,
                                             GRegexMatchFlags match_options);
gboolean    g_regex_match_next_full         (GRegex *regex,
                                             const gchar *string,
                                             gssize string_len,
                                             gint start_position,
                                             GRegexMatchFlags match_options,
                                             GError **error);
gboolean    g_regex_match_all               (GRegex *regex,
                                             const gchar *string,
                                             GRegexMatchFlags match_options);
gboolean    g_regex_match_all_full          (GRegex *regex,
                                             const gchar *string,
                                             gssize string_len,
                                             gint start_position,
                                             GRegexMatchFlags match_options,
                                             GError **error);
gint        g_regex_get_match_count         (const GRegex *regex);
gboolean    g_regex_is_partial_match        (const GRegex *regex);
gchar*      g_regex_fetch                   (const GRegex *regex,
                                             gint match_num,
                                             const gchar *string);
gboolean    g_regex_fetch_pos               (const GRegex *regex,
                                             gint match_num,
                                             gint *start_pos,
                                             gint *end_pos);
gchar*      g_regex_fetch_named             (const GRegex *regex,
                                             const gchar *name,
                                             const gchar *string);
gboolean    g_regex_fetch_named_pos         (const GRegex *regex,
                                             const gchar *name,
                                             gint *start_pos,
                                             gint *end_pos);
gchar**     g_regex_fetch_all               (const GRegex *regex,
                                             const gchar *string);
gint        g_regex_get_string_number       (const GRegex *regex,
                                             const gchar *name);
gchar**     g_regex_split_simple            (const gchar *pattern,
                                             const gchar *string,
                                             GRegexCompileFlags compile_options,
                                             GRegexMatchFlags match_options);
gchar**     g_regex_split                   (GRegex *regex,
                                             const gchar *string,
                                             GRegexMatchFlags match_options);
gchar**     g_regex_split_full              (GRegex *regex,
                                             const gchar *string,
                                             gssize string_len,
                                             gint start_position,
                                             GRegexMatchFlags match_options,
                                             gint max_tokens,
                                             GError **error);
gchar*      g_regex_split_next              (GRegex *regex,
                                             const gchar *string,
                                             GRegexMatchFlags match_options);
gchar*      g_regex_split_next_full         (GRegex *regex,
                                             const gchar *string,
                                             gssize string_len,
                                             gint start_position,
                                             GRegexMatchFlags match_options,
                                             GError **error);
gchar*      g_regex_expand_references       (GRegex *regex,
                                             const gchar *string,
                                             const gchar *string_to_expand,
                                             GError **error);
gchar*      g_regex_replace                 (GRegex *regex,
                                             const gchar *string,
                                             gssize string_len,
                                             gint start_position,
                                             const gchar *replacement,
                                             GRegexMatchFlags match_options,
                                             GError **error);
gchar*      g_regex_replace_literal         (GRegex *regex,
                                             const gchar *string,
                                             gssize string_len,
                                             gint start_position,
                                             const gchar *replacement,
                                             GRegexMatchFlags match_options,
                                             GError **error);
gchar*      g_regex_replace_eval            (GRegex *regex,
                                             const gchar *string,
                                             gssize string_len,
                                             gint start_position,
                                             GRegexMatchFlags match_options,
                                             GRegexEvalCallback eval,
                                             gpointer user_data,
                                             GError **error);
gchar*      g_regex_escape_string           (const gchar *string,
                                             gint length);

Description

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.

If you have two threads manipulating the same GRegex, they must use a lock to synchronize their operation, as these functions are not threadsafe. Creating and manipulating different GRegex structures from different threads is not a problem.

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

Details

enum GRegexError

typedef enum
{
  G_REGEX_ERROR_COMPILE,
  G_REGEX_ERROR_OPTIMIZE,
  G_REGEX_ERROR_REPLACE,
  G_REGEX_ERROR_MATCH
} GRegexError;

Error codes returned by regular expressions functions.

G_REGEX_ERROR_COMPILE Compilation of the regular expression in g_regex_new() failed.
G_REGEX_ERROR_OPTIMIZE Optimization of the regular expression in g_regex_optimize() failed.
G_REGEX_ERROR_REPLACE Replacement failed due to an ill-formed replacement string.
G_REGEX_ERROR_MATCH The match process failed.

Since 2.14


G_REGEX_ERROR

#define G_REGEX_ERROR g_regex_error_quark ()

Error domain for regular expressions. Errors in this domain will be from the GRegexError enumeration. See GError for information on error domains.

Since 2.14


enum GRegexCompileFlags

typedef enum
{
  G_REGEX_CASELESS          = 1 << 0,
  G_REGEX_MULTILINE         = 1 << 1,
  G_REGEX_DOTALL            = 1 << 2,
  G_REGEX_EXTENDED          = 1 << 3,
  G_REGEX_ANCHORED          = 1 << 4,
  G_REGEX_DOLLAR_ENDONLY    = 1 << 5,
  G_REGEX_UNGREEDY          = 1 << 9,
  G_REGEX_RAW               = 1 << 11,
  G_REGEX_NO_AUTO_CAPTURE   = 1 << 12,
  G_REGEX_DUPNAMES          = 1 << 19,
  G_REGEX_NEWLINE_CR        = 1 << 20,
  G_REGEX_NEWLINE_LF        = 1 << 21,
  G_REGEX_NEWLINE_CRLF      = G_REGEX_NEWLINE_CR | G_REGEX_NEWLINE_LF
} GRegexCompileFlags;

Flags specifying compile-time options.

G_REGEX_CASELESS Letters in the pattern match both upper and lower case letters. It be changed within a pattern by a "(?i)" option setting.
G_REGEX_MULTILINE By default, GRegex treats the strings as consisting of a single line of characters (even if it actually contains newlines). The "start of line" metacharacter ("^") matches only at the start of the string, while the "end of line" metacharacter ("$") matches only at the end of the string, or before a terminating newline (unless G_REGEX_DOLLAR_ENDONLY is set). When G_REGEX_MULTILINE is set, the "start of line" and "end of line" constructs match immediately following or immediately before any newline in the string, respectively, as well as at the very start and end. This can be changed within a pattern by a "(?m)" option setting.
G_REGEX_DOTALL A dot metacharater (".") in the pattern matches all characters, including newlines. Without it, newlines are excluded. This option can be changed within a pattern by a ("?s") option setting.
G_REGEX_EXTENDED Whitespace data characters in the pattern are totally ignored except when escaped or inside a character class. Whitespace does not include the VT character (code 11). In addition, characters between an unescaped "#" outside a character class and the next newline character, inclusive, are also ignored. This can be changed within a pattern by a "(?x)" option setting.
G_REGEX_ANCHORED The pattern is forced to be "anchored", that is, it is constrained to match only at the first matching point in the string that is being searched. This effect can also be achieved by appropriate constructs in the pattern itself such as the "^" metacharater.
G_REGEX_DOLLAR_ENDONLY A dollar metacharacter ("$") in the pattern matches only at the end of the string. Without this option, a dollar also matches immediately before the final character if it is a newline (but not before any other newlines). This option is ignored if G_REGEX_MULTILINE is set.
G_REGEX_UNGREEDY Inverts the "greediness" of the quantifiers so that they are not greedy by default, but become greedy if followed by "?". It can also be set by a "(?U)" option setting within the pattern.
G_REGEX_RAW Usually strings must be valid UTF-8 strings, using this flag they are considered as a raw sequence of bytes.
G_REGEX_NO_AUTO_CAPTURE Disables the use of numbered capturing parentheses in the pattern. Any opening parenthesis that is not followed by "?" behaves as if it were followed by "?:" but named parentheses can still be used for capturing (and they acquire numbers in the usual way).
G_REGEX_DUPNAMES Names used to identify capturing subpatterns need not be unique. This can be helpful for certain types of pattern when it is known that only one instance of the named subpattern can ever be matched.
G_REGEX_NEWLINE_CR Usually any newline character is recognized, if this option is set, the only recognized newline character is '\r'.
G_REGEX_NEWLINE_LF Usually any newline character is recognized, if this option is set, the only recognized newline character is '\n'.
G_REGEX_NEWLINE_CRLF Usually any newline character is recognized, if this option is set, the only recognized newline character sequence is '\r\n'.

Since 2.14


enum GRegexMatchFlags

typedef enum
{
  G_REGEX_MATCH_ANCHORED      = 1 << 4,
  G_REGEX_MATCH_NOTBOL        = 1 << 7,
  G_REGEX_MATCH_NOTEOL        = 1 << 8,
  G_REGEX_MATCH_NOTEMPTY      = 1 << 10,
  G_REGEX_MATCH_PARTIAL       = 1 << 15,
  G_REGEX_MATCH_NEWLINE_CR    = 1 << 20,
  G_REGEX_MATCH_NEWLINE_LF    = 1 << 21,
  G_REGEX_MATCH_NEWLINE_CRLF  = G_REGEX_MATCH_NEWLINE_CR | G_REGEX_MATCH_NEWLINE_LF,
  G_REGEX_MATCH_NEWLINE_ANY   = 1 << 22,
} GRegexMatchFlags;

Flags specifying match-time options.

G_REGEX_MATCH_ANCHORED The pattern is forced to be "anchored", that is, it is constrained to match only at the first matching point in the string that is being searched. This effect can also be achieved by appropriate constructs in the pattern itself such as the "^" metacharater.
G_REGEX_MATCH_NOTBOL Specifies that first character of the string is not the beginning of a line, so the circumflex metacharacter should not match before it. Setting this without G_REGEX_MULTILINE (at compile time) causes circumflex never to match. This option affects only the behaviour of the circumflex metacharacter, it does not affect "\A".
G_REGEX_MATCH_NOTEOL Specifies that the end of the subject string is not the end of a line, so the dollar metacharacter should not match it nor (except in multiline mode) a newline immediately before it. Setting this without G_REGEX_MULTILINE (at compile time) causes dollar never to match. This option affects only the behaviour of the dollar metacharacter, it does not affect "\Z" or "\z".
G_REGEX_MATCH_NOTEMPTY An empty string is not considered to be a valid match if this option is set. If there are alternatives in the pattern, they are tried. If all the alternatives match the empty string, the entire match fails. For example, if the pattern "a?b?" is applied to a string not beginning with "a" or "b", it matches the empty string at the start of the string. With this flag set, this match is not valid, so GRegex searches further into the string for occurrences of "a" or "b".
G_REGEX_MATCH_PARTIAL Turns on the partial matching feature, for more documentation on partial matching see g_regex_is_partial_match().
G_REGEX_MATCH_NEWLINE_CR Overrides the newline definition set when creating a new GRegex, setting the '\r' character as line terminator.
G_REGEX_MATCH_NEWLINE_LF Overrides the newline definition set when creating a new GRegex, setting the '\n' character as line terminator.
G_REGEX_MATCH_NEWLINE_CRLF Overrides the newline definition set when creating a new GRegex, setting the '\r\n' characters as line terminator.
G_REGEX_MATCH_NEWLINE_ANY Overrides the newline definition set when creating a new GRegex, any newline character or character sequence is recognized.

Since 2.14


GRegex

typedef struct _GRegex GRegex;

A GRegex is the "compiled" form of a regular expression pattern. This structure is opaque and its fields cannot be accessed directly.

Since 2.14


GRegexEvalCallback ()

gboolean    (*GRegexEvalCallback)           (const GRegex *,
                                             const gchar *,
                                             GString *,
                                             gpointer );

Specifies the type of the function passed to g_regex_replace_eval(). It is called for each occurance of the pattern regex in string, and it should append the replacement to result.

Do not call on regex functions that modify its internal state, such as g_regex_match(); if you need it you can create a temporary copy of regex using g_regex_copy().

Param1 : a GRegex.
Param2 : the string used to perform matches against.
Param3 : a GString containing the new string.
Param4 : user data passed to g_regex_replace_eval().
Returns : FALSE to continue the replacement process, TRUE to stop it.

Since 2.14


g_regex_new ()

GRegex*     g_regex_new                     (const gchar *pattern,
                                             GRegexCompileFlags compile_options,
                                             GRegexMatchFlags match_options,
                                             GError **error);

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

pattern : the regular expression.
compile_options : compile options for the regular expression.
match_options : match options for the regular expression.
error : return location for a GError.
Returns : a GRegex structure.

Since 2.14


g_regex_free ()

void        g_regex_free                    (GRegex *regex);

Frees all the memory associated with the regex structure.

regex : a GRegex.

Since 2.14


g_regex_optimize ()

gboolean    g_regex_optimize                (GRegex *regex,
                                             GError **error);

If the pattern will be used many times, then it may be worth the effort to optimize it to improve the speed of matches.

regex : a GRegex structure.
error : return location for a GError.
Returns : TRUE if regex has been optimized or was already optimized, FALSE otherwise.

Since 2.14


g_regex_copy ()

GRegex*     g_regex_copy                    (const GRegex *regex);

Copies a GRegex. The returned Gregex is in the same state as after a call to g_regex_clear(), so it does not contain information on the last match. If regex is NULL it returns NULL.

The returned copy shares some of its internal state with the original regex, and the other internal variables are created only when needed, so the copy is a lightweight operation.

regex : a GRegex structure from g_regex_new().
Returns : a newly allocated copy of regex, or NULL if an error occurred.

Since 2.14


g_regex_get_pattern ()

const gchar* g_regex_get_pattern            (const GRegex *regex);

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

regex : a GRegex structure.
Returns : the pattern of regex.

Since 2.14


g_regex_clear ()

void        g_regex_clear                   (GRegex *regex);

Clears out the members of regex that are holding information about the last set of matches for this pattern. g_regex_clear() needs to be called between uses of g_regex_match_next() or g_regex_match_next_full() against new target strings.

regex : a GRegex structure.

Since 2.14


g_regex_match_simple ()

gboolean    g_regex_match_simple            (const gchar *pattern,
                                             const gchar *string,
                                             GRegexCompileFlags compile_options,
                                             GRegexMatchFlags match_options);

Scans for a match in string for pattern.

This function is equivalent to g_regex_match() but it does not require to compile the pattern with g_regex_new(), avoiding some lines of code when you need just to do a match without extracting substrings, capture counts, and so on.

If this function is to be called on the same pattern more than once, it's more efficient to compile the pattern once with g_regex_new() and then use g_regex_match().

pattern : the regular expression.
string : the string to scan for matches.
compile_options : compile options for the regular expression.
match_options : match options.
Returns : TRUE is the string matched, FALSE otherwise.

Since 2.14


g_regex_match ()

gboolean    g_regex_match                   (GRegex *regex,
                                             const gchar *string,
                                             GRegexMatchFlags match_options);

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.

regex : a GRegex structure from g_regex_new().
string : the string to scan for matches.
match_options : match options.
Returns : TRUE is the string matched, FALSE otherwise.

Since 2.14


g_regex_match_full ()

gboolean    g_regex_match_full              (GRegex *regex,
                                             const gchar *string,
                                             gssize string_len,
                                             gint start_position,
                                             GRegexMatchFlags match_options,
                                             GError **error);

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.

Setting start_position 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, such as "\b".

regex : a GRegex structure from g_regex_new().
string : the string to scan for matches.
string_len : the length of string, or -1 if string is nul-terminated.
start_position : starting index of the string to match.
match_options : match options.
error : location to store the error occuring, or NULL to ignore errors.
Returns : TRUE is the string matched, FALSE otherwise.

Since 2.14


g_regex_match_next ()

gboolean    g_regex_match_next              (GRegex *regex,
                                             const gchar *string,
                                             GRegexMatchFlags match_options);

Scans for the next match in string of the pattern in regex. array. The match options are combined with the match options set when the regex was created.

You have to call g_regex_clear() to reuse the same pattern on a new string.

regex : a GRegex structure.
string : the string to scan for matches.
match_options : the match options.
Returns : TRUE is the string matched, FALSE otherwise.

Since 2.14


g_regex_match_next_full ()

gboolean    g_regex_match_next_full         (GRegex *regex,
                                             const gchar *string,
                                             gssize string_len,
                                             gint start_position,
                                             GRegexMatchFlags match_options,
                                             GError **error);

Scans for the next match in string of the pattern in regex. Calling g_regex_match_next_full() until it returns FALSE, you can retrieve all the non-overlapping matches of the pattern in string. Empty matches are included, so matching the string "ab" with the pattern "b*" will find three matches: "" at position 0, "b" from position 1 to 2 and "" at position 2.

The match options are combined with the match options set when the regex was created.

You have to call g_regex_clear() to reuse the same pattern on a new string.

Setting start_position 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, such as "\b".

regex : a GRegex structure.
string : the string to scan for matches.
string_len : the length of string, or -1 if string is nul-terminated.
start_position : starting index of the string to match.
match_options : the match options.
error : location to store the error occuring, or NULL to ignore errors.
Returns : TRUE is the string matched, FALSE otherwise.

Since 2.14


g_regex_match_all ()

gboolean    g_regex_match_all               (GRegex *regex,
                                             const gchar *string,
                                             GRegexMatchFlags match_options);

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().

regex : a GRegex structure from g_regex_new().
string : the string to scan for matches.
match_options : match options.
Returns : TRUE is the string matched, FALSE otherwise.

Since 2.14


g_regex_match_all_full ()

gboolean    g_regex_match_all_full          (GRegex *regex,
                                             const gchar *string,
                                             gssize string_len,
                                             gint start_position,
                                             GRegexMatchFlags match_options,
                                             GError **error);

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

This function uses a different algorithm (called DFA, i.e. deterministic finite automaton), so it can retrieve all the possible matches, all starting at the same point in the string. For instance matching "<a> <b> <c>" against the pattern "<.*>" you would obtain three matches: "<a> <b> <c>", "<a> <b>" and "<a>".

The number of matched strings is retrieved using g_regex_get_match_count(). To obtain the matched strings and their position you can use, respectively, g_regex_fetch() and g_regex_fetch_pos(). Note that the strings are returned in reverse order of length; that is, the longest matching string is given first.

Note that the DFA algorithm is slower than the standard one and it is not able to capture substrings, so backreferences do not work.

Setting start_position 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, such as "\b".

regex : a GRegex structure from g_regex_new().
string : the string to scan for matches.
string_len : the length of string, or -1 if string is nul-terminated.
start_position : starting index of the string to match.
match_options : match options.
error : location to store the error occuring, or NULL to ignore errors.
Returns : TRUE is the string matched, FALSE otherwise.

Since 2.14


g_regex_get_match_count ()

gint        g_regex_get_match_count         (const GRegex *regex);

Retrieves the number of matched substrings (including substring 0, that is the whole matched text) in the last call to g_regex_match*(), so 1 is returned if the pattern has no substrings in it and 0 is returned if the match failed.

If the last match was obtained using the DFA algorithm, that is using g_regex_match_all() or g_regex_match_all_full(), the retrieved count is not that of the number of capturing parentheses but that of the number of matched substrings.

regex : a GRegex structure.
Returns : Number of matched substrings, or -1 if an error occurred.

Since 2.14


g_regex_is_partial_match ()

gboolean    g_regex_is_partial_match        (const GRegex *regex);

Usually if the string passed to g_regex_match*() matches as far as it goes, but is too short to match the entire pattern, FALSE is returned. There are circumstances where it might be helpful to distinguish this case from other cases in which there is no match.

Consider, for example, an application where a human is required to type in data for a field with specific formatting requirements. An example might be a date in the form ddmmmyy, defined by the pattern "^\d?\d(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)\d\d$". If the application sees the user’s keystrokes one by one, and can check that what has been typed so far is potentially valid, it is able to raise an error as soon as a mistake is made.

GRegex supports the concept of partial matching by means of the G_REGEX_MATCH_PARTIAL flag. When this is set the return code for g_regex_match() or g_regex_match_full() is, as usual, TRUE for a complete match, FALSE otherwise. But, when this functions returns FALSE, you can check if the match was partial calling g_regex_is_partial_match().

When using partial matching you cannot use g_regex_fetch*().

Because of the way certain internal optimizations are implemented the partial matching algorithm cannot be used with all patterns. So repeated single characters such as "a{2,4}" and repeated single metasequences such as "\d+" are not permitted if the maximum number of occurrences is greater than one. Optional items such as "\d?" (where the maximum is one) are permitted. Quantifiers with any values are permitted after parentheses, so the invalid examples above can be coded thus "(a){2,4}" and "(\d)+". If G_REGEX_MATCH_PARTIAL is set for a pattern that does not conform to the restrictions, matching functions return an error.

regex : a GRegex structure.
Returns : TRUE if the match was partial, FALSE otherwise.

Since 2.14


g_regex_fetch ()

gchar*      g_regex_fetch                   (const GRegex *regex,
                                             gint match_num,
                                             const gchar *string);

Retrieves the text matching the match_num'th capturing parentheses. 0 is the full text of the match, 1 is the first paren set, 2 the second, and so on.

If match_num is a valid sub pattern but it didn't match anything (e.g. sub pattern 1, matching "b" against "(a)?b") then an empty string is returned.

If the last match was obtained using the DFA algorithm, that is using g_regex_match_all() or g_regex_match_all_full(), the retrieved string is not that of a set of parentheses but that of a matched substring. Substrings are matched in reverse order of length, so 0 is the longest match.

regex : GRegex structure used in last match.
match_num : number of the sub expression.
string : the string on which the last match was made.
Returns : The matched substring, or NULL if an error occurred. You have to free the string yourself.

Since 2.14


g_regex_fetch_pos ()

gboolean    g_regex_fetch_pos               (const GRegex *regex,
                                             gint match_num,
                                             gint *start_pos,
                                             gint *end_pos);

Retrieves the position of the match_num'th capturing parentheses. 0 is the full text of the match, 1 is the first paren set, 2 the second, and so on.

If match_num is a valid sub pattern but it didn't match anything (e.g. sub pattern 1, matching "b" against "(a)?b") then start_pos and end_pos are set to -1 and TRUE is returned.

If the last match was obtained using the DFA algorithm, that is using g_regex_match_all() or g_regex_match_all_full(), the retrieved position is not that of a set of parentheses but that of a matched substring. Substrings are matched in reverse order of length, so 0 is the longest match.

regex : GRegex structure used in last match.
match_num : number of the sub expression.
start_pos : pointer to location where to store the start position.
end_pos : pointer to location where to store the end position.
Returns : TRUE if the position was fetched, FALSE otherwise. If the position cannot be fetched, start_pos and end_pos are left unchanged.

Since 2.14


g_regex_fetch_named ()

gchar*      g_regex_fetch_named             (const GRegex *regex,
                                             const gchar *name,
                                             const gchar *string);

Retrieves the text matching the capturing parentheses named name.

If name is a valid sub pattern name but it didn't match anything (e.g. sub pattern "X", matching "b" against "(?P<X>a)?b") then an empty string is returned.

regex : GRegex structure used in last match.
name : name of the subexpression.
string : the string on which the last match was made.
Returns : The matched substring, or NULL if an error occurred. You have to free the string yourself.

Since 2.14


g_regex_fetch_named_pos ()

gboolean    g_regex_fetch_named_pos         (const GRegex *regex,
                                             const gchar *name,
                                             gint *start_pos,
                                             gint *end_pos);

Retrieves the position of the capturing parentheses named name.

If name is a valid sub pattern name but it didn't match anything (e.g. sub pattern "X", matching "b" against "(?P<X>a)?b") then start_pos and end_pos are set to -1 and TRUE is returned.

regex : GRegex structure used in last match.
name : name of the subexpression.
start_pos : pointer to location where to store the start position.
end_pos : pointer to location where to store the end position.
Returns : TRUE if the position was fetched, FALSE otherwise. If the position cannot be fetched, start_pos and end_pos are left unchanged.

Since 2.14


g_regex_fetch_all ()

gchar**     g_regex_fetch_all               (const GRegex *regex,
                                             const gchar *string);

Bundles up pointers to each of the matching substrings from a match and stores them in an array of gchar pointers. The first element in the returned array is the match number 0, i.e. the entire matched text.

If a sub pattern didn't match anything (e.g. sub pattern 1, matching "b" against "(a)?b") then an empty string is inserted.

If the last match was obtained using the DFA algorithm, that is using g_regex_match_all() or g_regex_match_all_full(), the retrieved strings are not that matched by sets of parentheses but that of the matched substring. Substrings are matched in reverse order of length, so the first one is the longest match.

regex : a GRegex structure.
string : the string on which the last match was made.
Returns : a NULL-terminated array of gchar * pointers. It must be freed using g_strfreev(). If the memory can't be allocated, returns NULL.

Since 2.14


g_regex_get_string_number ()

gint        g_regex_get_string_number       (const GRegex *regex,
                                             const gchar *name);

Retrieves the number of the subexpression named name.

regex : GRegex structure.
name : name of the subexpression.
Returns : The number of the subexpression or -1 if name does not exists.

Since 2.14


g_regex_split_simple ()

gchar**     g_regex_split_simple            (const gchar *pattern,
                                             const gchar *string,
                                             GRegexCompileFlags compile_options,
                                             GRegexMatchFlags match_options);

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.

This function is equivalent to g_regex_split() but it does not require to compile the pattern with g_regex_new(), avoiding some lines of code when you need just to do a split without extracting substrings, capture counts, and so on.

If this function is to be called on the same pattern more than once, it's more efficient to compile the pattern once with g_regex_new() and then use g_regex_split().

As a special case, the result of splitting the empty string "" is an empty vector, not a vector containing a single string. The reason for this special case is that being able to represent a empty vector is typically more useful than consistent handling of empty elements. If you do need to represent empty elements, you'll need to check for the empty string before calling this function.

A pattern that can match empty strings splits string into separate characters wherever it matches the empty string between characters. For example splitting "ab c" using as a separator "\s*", you will get "a", "b" and "c".

pattern : the regular expression.
string : the string to scan for matches.
compile_options : compile options for the regular expression.
match_options : match options.
Returns : a NULL-terminated gchar ** array. Free it using g_strfreev().

Since 2.14


g_regex_split ()

gchar**     g_regex_split                   (GRegex *regex,
                                             const gchar *string,
                                             GRegexMatchFlags match_options);

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.

As a special case, the result of splitting the empty string "" is an empty vector, not a vector containing a single string. The reason for this special case is that being able to represent a empty vector is typically more useful than consistent handling of empty elements. If you do need to represent empty elements, you'll need to check for the empty string before calling this function.

A pattern that can match empty strings splits string into separate characters wherever it matches the empty string between characters. For example splitting "ab c" using as a separator "\s*", you will get "a", "b" and "c".

regex : a GRegex structure.
string : the string to split with the pattern.
match_options : match time option flags.
Returns : a NULL-terminated gchar ** array. Free it using g_strfreev().

Since 2.14


g_regex_split_full ()

gchar**     g_regex_split_full              (GRegex *regex,
                                             const gchar *string,
                                             gssize string_len,
                                             gint start_position,
                                             GRegexMatchFlags match_options,
                                             gint max_tokens,
                                             GError **error);

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.

As a special case, the result of splitting the empty string "" is an empty vector, not a vector containing a single string. The reason for this special case is that being able to represent a empty vector is typically more useful than consistent handling of empty elements. If you do need to represent empty elements, you'll need to check for the empty string before calling this function.

A pattern that can match empty strings splits string into separate characters wherever it matches the empty string between characters. For example splitting "ab c" using as a separator "\s*", you will get "a", "b" and "c".

Setting start_position 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, such as "\b".

regex : a GRegex structure.
string : the string to split with the pattern.
string_len : the length of string, or -1 if string is nul-terminated.
start_position : starting index of the string to match.
match_options : match time option flags.
max_tokens : the maximum number of tokens to split string into. If this is less than 1, the string is split completely.
error : return location for a GError.
Returns : a NULL-terminated gchar ** array. Free it using g_strfreev().

Since 2.14


g_regex_split_next ()

gchar*      g_regex_split_next              (GRegex *regex,
                                             const gchar *string,
                                             GRegexMatchFlags match_options);

g_regex_split_next() breaks the string on pattern, and returns the tokens, one per call. 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.

A pattern that can match empty strings splits string into separate characters wherever it matches the empty string between characters. For example splitting "ab c" using as a separator "\s*", you will get "a", "b" and "c".

You have to call g_regex_clear() to reuse the same pattern on a new string.

regex : a GRegex structure from g_regex_new().
string : the string to split on pattern.
match_options : match time options for the regex.
Returns : a gchar * to the next token of the string.

Since 2.14


g_regex_split_next_full ()

gchar*      g_regex_split_next_full         (GRegex *regex,
                                             const gchar *string,
                                             gssize string_len,
                                             gint start_position,
                                             GRegexMatchFlags match_options,
                                             GError **error);

g_regex_split_next_full() breaks the string on pattern, and returns the tokens, one per call. 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.

A pattern that can match empty strings splits string into separate characters wherever it matches the empty string between characters. For example splitting "ab c" using as a separator "\s*", you will get "a", "b" and "c".

You have to call g_regex_clear() to reuse the same pattern on a new string.

Setting start_position 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, such as "\b".

regex : a GRegex structure from g_regex_new().
string : the string to split on pattern.
string_len : the length of string, or -1 if string is nul-terminated.
start_position : starting index of the string to match.
match_options : match time options for the regex.
error : return location for a GError.
Returns : a gchar * to the next token of the string.

Since 2.14


g_regex_expand_references ()

gchar*      g_regex_expand_references       (GRegex *regex,
                                             const gchar *string,
                                             const gchar *string_to_expand,
                                             GError **error);

Returns a new string containing the text in string_to_expand with references expanded. References refer to the last match done with string against regex and have the same syntax used by g_regex_replace().

The string_to_expand must be UTF-8 encoded even if G_REGEX_RAW was passed to g_regex_new().

regex : GRegex structure used in last match.
string : the string on which the last match was made.
string_to_expand : the string to expand.
error : location to store the error occuring, or NULL to ignore errors.
Returns : the expanded string, or NULL if an error occurred.

Since 2.14


g_regex_replace ()

gchar*      g_regex_replace                 (GRegex *regex,
                                             const gchar *string,
                                             gssize string_len,
                                             gint start_position,
                                             const gchar *replacement,
                                             GRegexMatchFlags match_options,
                                             GError **error);

Replaces all occurances of the pattern in regex with the replacement text. Backreferences of the form '\number' or '\g<number>' in the replacement text are interpolated by the number-th captured subexpression of the match, '\g<name>' 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 '\\'. There are also escapes that changes the case of the following text:

\l

Convert to lower case the next character

\u

Convert to upper case the next character

\L

Convert to lower case till \E

\U

Convert to upper case till \E

\E

End case modification

If you do not need to use backreferences use g_regex_replace_literal().

The replacement string must be UTF-8 encoded even if G_REGEX_RAW was passed to g_regex_new(). If you want to use not UTF-8 encoded stings you can use g_regex_replace_literal().

Setting start_position 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, such as "\b".

regex : a GRegex structure.
string : the string to perform matches against.
string_len : the length of string, or -1 if string is nul-terminated.
start_position : starting index of the string to match.
replacement : text to replace each match with.
match_options : options for the match.
error : location to store the error occuring, or NULL to ignore errors.
Returns : a newly allocated string containing the replacements.

Since 2.14


g_regex_replace_literal ()

gchar*      g_regex_replace_literal         (GRegex *regex,
                                             const gchar *string,
                                             gssize string_len,
                                             gint start_position,
                                             const gchar *replacement,
                                             GRegexMatchFlags match_options,
                                             GError **error);

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

Setting start_position 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, such as "\b".

regex : a GRegex structure.
string : the string to perform matches against.
string_len : the length of string, or -1 if string is nul-terminated.
start_position : starting index of the string to match.
replacement : text to replace each match with.
match_options : options for the match.
error : location to store the error occuring, or NULL to ignore errors.
Returns : a newly allocated string containing the replacements.

Since 2.14


g_regex_replace_eval ()

gchar*      g_regex_replace_eval            (GRegex *regex,
                                             const gchar *string,
                                             gssize string_len,
                                             gint start_position,
                                             GRegexMatchFlags match_options,
                                             GRegexEvalCallback eval,
                                             gpointer user_data,
                                             GError **error);

Replaces occurances of the pattern in regex with the output of eval for that occurance.

Setting start_position 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, such as "\b".

regex : a GRegex structure from g_regex_new().
string : string to perform matches against.
string_len : the length of string, or -1 if string is nul-terminated.
start_position : starting index of the string to match.
match_options : Options for the match.
eval : a function to call for each match.
user_data : user data to pass to the function.
error : location to store the error occuring, or NULL to ignore errors.
Returns : a newly allocated string containing the replacements.

Since 2.14


g_regex_escape_string ()

gchar*      g_regex_escape_string           (const gchar *string,
                                             gint length);

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.

string can contain NULL characters that are replaced with "\0", in this case remember to specify the correct length of string in length.

string : the string to escape.
length : the length of string, or -1 if string is nul-terminated.
Returns : a newly allocated escaped string.

Since 2.14