GRegexEvalCallback ()

gboolean
(*GRegexEvalCallback) (const GMatchInfo *match_info,
                       GString *result,
                       gpointer user_data);

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

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.

Since 2.14

g_regex_ref ()

GRegex *
g_regex_ref (GRegex *regex);

Increases reference count of regex by 1.

Since 2.14

g_regex_unref ()

void
g_regex_unref (GRegex *regex);

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

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().

Since 2.14

g_regex_get_max_backref ()

gint
g_regex_get_max_backref (const GRegex *regex);

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

Since 2.14

g_regex_get_capture_count ()

gint
g_regex_get_capture_count (const GRegex *regex);

Returns the number of capturing subpatterns in the pattern.

Since 2.14

g_regex_get_has_cr_or_lf ()

gboolean
g_regex_get_has_cr_or_lf (const GRegex *regex);

Checks whether the pattern contains explicit CR or LF references.

Since 2.34

g_regex_get_max_lookbehind ()

gint
g_regex_get_max_lookbehind (const GRegex *regex);

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.

Since 2.38

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 .

Since 2.14

g_regex_get_compile_flags ()

GRegexCompileFlags
g_regex_get_compile_flags (const GRegex *regex);

Returns the compile options that regex was created with.

Since 2.26

g_regex_get_match_flags ()

GRegexMatchFlags
g_regex_get_match_flags (const GRegex *regex);

Returns the match options that regex was created with.

Since 2.26

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

Since 2.14

g_regex_escape_nul ()

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

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

For completeness, length can be -1 for a nul-terminated string. In this case the output string will be of course equal to string .

Since 2.30

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().

Since 2.14

g_regex_match ()

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

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.

A GMatchInfo structure, used to get information on the match, is stored in match_info if not NULL. Note that if match_info is not NULL then it is created even if the function returns FALSE, i.e. you must free it regardless if regular expression actually matched.

To retrieve all the non-overlapping matches of the pattern in string you can use g_match_info_next().

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static void
print_uppercase_words (const gchar *string)
{
  // Print all uppercase-only words.
  GRegex *regex;
  GMatchInfo *match_info;
 
  regex = g_regex_new ("[A-Z]+", 0, 0, NULL);
  g_regex_match (regex, string, 0, &match_info);
  while (g_match_info_matches (match_info))
    {
      gchar *word = g_match_info_fetch (match_info, 0);
      g_print ("Found: %s\n", word);
      g_free (word);
      g_match_info_next (match_info, NULL);
    }
  g_match_info_free (match_info);
  g_regex_unref (regex);
}

string is not copied and is used in GMatchInfo internally. If you use any GMatchInfo method (except g_match_info_free()) after freeing or modifying string then the behaviour is undefined.

Since 2.14

g_regex_match_full ()

gboolean
g_regex_match_full (const GRegex *regex,
                    const gchar *string,
                    gssize string_len,
                    gint start_position,
                    GRegexMatchFlags match_options,
                    GMatchInfo **match_info,
                    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".

A GMatchInfo structure, used to get information on the match, is stored in match_info if not NULL. Note that if match_info is not NULL then it is created even if the function returns FALSE, i.e. you must free it regardless if regular expression actually matched.

string is not copied and is used in GMatchInfo internally. If you use any GMatchInfo method (except g_match_info_free()) after freeing or modifying string then the behaviour is undefined.

To retrieve all the non-overlapping matches of the pattern in string you can use g_match_info_next().

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static void
print_uppercase_words (const gchar *string)
{
  // Print all uppercase-only words.
  GRegex *regex;
  GMatchInfo *match_info;
  GError *error = NULL;
  
  regex = g_regex_new ("[A-Z]+", 0, 0, NULL);
  g_regex_match_full (regex, string, -1, 0, 0, &match_info, &error);
  while (g_match_info_matches (match_info))
    {
      gchar *word = g_match_info_fetch (match_info, 0);
      g_print ("Found: %s\n", word);
      g_free (word);
      g_match_info_next (match_info, &error);
    }
  g_match_info_free (match_info);
  g_regex_unref (regex);
  if (error != NULL)
    {
      g_printerr ("Error while matching: %s\n", error->message);
      g_error_free (error);
    }
}

Since 2.14

g_regex_match_all ()

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

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().

A GMatchInfo structure, used to get information on the match, is stored in match_info if not NULL. Note that if match_info is not NULL then it is created even if the function returns FALSE, i.e. you must free it regardless if regular expression actually matched.

string is not copied and is used in GMatchInfo internally. If you use any GMatchInfo method (except g_match_info_free()) after freeing or modifying string then the behaviour is undefined.

Since 2.14

g_regex_match_all_full ()

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

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 "<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_match_info_get_match_count(). To obtain the matched strings and their position you can use, respectively, g_match_info_fetch() and g_match_info_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".

A GMatchInfo structure, used to get information on the match, is stored in match_info if not NULL. Note that if match_info is not NULL then it is created even if the function returns FALSE, i.e. you must free it regardless if regular expression actually matched.

string is not copied and is used in GMatchInfo internally. If you use any GMatchInfo method (except g_match_info_free()) after freeing or modifying string then the behaviour is undefined.

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".

Since 2.14

g_regex_split ()

gchar **
g_regex_split (const 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".

Since 2.14

g_regex_split_full ()

gchar **
g_regex_split_full (const 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".

Since 2.14

g_regex_replace ()

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

Replaces all occurrences 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:

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".

Since 2.14

g_regex_replace_literal ()

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

Replaces all occurrences 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".

Since 2.14

g_regex_replace_eval ()

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

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

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".

The following example uses g_regex_replace_eval() to replace multiple strings at once:

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static gboolean
eval_cb (const GMatchInfo *info,
         GString          *res,
         gpointer          data)
{
  gchar *match;
  gchar *r;

   match = g_match_info_fetch (info, 0);
   r = g_hash_table_lookup ((GHashTable *)data, match);
   g_string_append (res, r);
   g_free (match);

   return FALSE;
}

...

GRegex *reg;
GHashTable *h;
gchar *res;

h = g_hash_table_new (g_str_hash, g_str_equal);

g_hash_table_insert (h, "1", "ONE");
g_hash_table_insert (h, "2", "TWO");
g_hash_table_insert (h, "3", "THREE");
g_hash_table_insert (h, "4", "FOUR");

reg = g_regex_new ("1|2|3|4", 0, 0, NULL);
res = g_regex_replace_eval (reg, text, -1, 0, 0, eval_cb, h, NULL);
g_hash_table_destroy (h);

...

Since 2.14

g_regex_check_replacement ()

gboolean
g_regex_check_replacement (const gchar *replacement,
                           gboolean *has_references,
                           GError **error);

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

If has_references is not NULL then replacement is checked for pattern references. For instance, replacement text 'foo\n' does not contain references and may be evaluated without information about actual match, but '\0\1' (whole match followed by first subpattern) requires valid GMatchInfo object.

Since 2.14

g_match_info_get_regex ()

GRegex *
g_match_info_get_regex (const GMatchInfo *match_info);

Returns GRegex object used in match_info . It belongs to Glib and must not be freed. Use g_regex_ref() if you need to keep it after you free match_info object.

Since 2.14

g_match_info_get_string ()

const gchar *
g_match_info_get_string (const GMatchInfo *match_info);

Returns the string searched with match_info . This is the string passed to g_regex_match() or g_regex_replace() so you may not free it before calling this function.

Since 2.14

g_match_info_ref ()

GMatchInfo *
g_match_info_ref (GMatchInfo *match_info);

Increases reference count of match_info by 1.

Since 2.30

g_match_info_unref ()

void
g_match_info_unref (GMatchInfo *match_info);

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

Since 2.30

g_match_info_free ()

void
g_match_info_free (GMatchInfo *match_info);

If match_info is not NULL, calls g_match_info_unref(); otherwise does nothing.

Since 2.14

g_match_info_matches ()

gboolean
g_match_info_matches (const GMatchInfo *match_info);

Returns whether the previous match operation succeeded.

Since 2.14

g_match_info_next ()

gboolean
g_match_info_next (GMatchInfo *match_info,
                   GError **error);

Scans for the next match using the same parameters of the previous call to g_regex_match_full() or g_regex_match() that returned match_info .

The match is done on the string passed to the match function, so you cannot free it before calling this function.

Since 2.14

g_match_info_get_match_count ()

gint
g_match_info_get_match_count (const GMatchInfo *match_info);

Retrieves the number of matched substrings (including substring 0, that is the whole matched text), 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.

Since 2.14

g_match_info_is_partial_match ()

gboolean
g_match_info_is_partial_match (const GMatchInfo *match_info);

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_SOFT and G_REGEX_MATCH_PARTIAL_HARD flags. When they are used, the return code for g_regex_match() or g_regex_match_full() is, as usual, TRUE for a complete match, FALSE otherwise. But, when these functions return FALSE, you can check if the match was partial calling g_match_info_is_partial_match().

The difference between G_REGEX_MATCH_PARTIAL_SOFT and G_REGEX_MATCH_PARTIAL_HARD is that when a partial match is encountered with G_REGEX_MATCH_PARTIAL_SOFT, matching continues to search for a possible complete match, while with G_REGEX_MATCH_PARTIAL_HARD matching stops at the partial match. When both G_REGEX_MATCH_PARTIAL_SOFT and G_REGEX_MATCH_PARTIAL_HARD are set, the latter takes precedence.

There were formerly some restrictions on the pattern for partial matching. The restrictions no longer apply.

See pcrepartial(3) for more information on partial matching.

Since 2.14

g_match_info_expand_references ()

gchar *
g_match_info_expand_references (const GMatchInfo *match_info,
                                const gchar *string_to_expand,
                                GError **error);

Returns a new string containing the text in string_to_expand with references and escape sequences 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().

The backreferences are extracted from the string passed to the match function, so you cannot call this function after freeing the string.

match_info may be NULL in which case string_to_expand must not contain references. For instance "foo\n" does not refer to an actual pattern and '\n' merely will be replaced with \n character, while to expand "\0" (whole match) one needs the result of a match. Use g_regex_check_replacement() to find out whether string_to_expand contains references.

Since 2.14

g_match_info_fetch ()

gchar *
g_match_info_fetch (const GMatchInfo *match_info,
                    gint match_num);

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 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.

The string is fetched from the string passed to the match function, so you cannot call this function after freeing the string.

Since 2.14

g_match_info_fetch_pos ()

gboolean
g_match_info_fetch_pos (const GMatchInfo *match_info,
                        gint match_num,
                        gint *start_pos,
                        gint *end_pos);

Retrieves the position in bytes 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 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.

Since 2.14

g_match_info_fetch_named ()

gchar *
g_match_info_fetch_named (const GMatchInfo *match_info,
                          const gchar *name);

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.

The string is fetched from the string passed to the match function, so you cannot call this function after freeing the string.

Since 2.14

g_match_info_fetch_named_pos ()

gboolean
g_match_info_fetch_named_pos (const GMatchInfo *match_info,
                              const gchar *name,
                              gint *start_pos,
                              gint *end_pos);

Retrieves the position in bytes 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.

Since 2.14

g_match_info_fetch_all ()

gchar **
g_match_info_fetch_all (const GMatchInfo *match_info);

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.

The strings are fetched from the string passed to the match function, so you cannot call this function after freeing the string.

Since 2.14

enum GRegexError

Error codes returned by regular expressions functions.

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

Flags specifying compile-time options.

Since 2.14

enum GRegexMatchFlags

Flags specifying match-time options.

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

GMatchInfo

typedef struct _GMatchInfo GMatchInfo;