[88:7] extends: object
A GRegex is a compiled form of a regular expression. After instantiating a
GRegex, you can use its methods to find matches in a string, replace
matches within a string, or split the string at matches. GRegex implements
regular expression pattern matching using syntax and semantics (such as
character classes, quantifiers, and capture groups) similar to Perl regular
expression. See the PCRE documentation for details. A
typical scenario for regex pattern matching is to check if a string matches a
pattern. The following statements implement this scenario. { .c } const char *regex_pattern = ".*GLib.*"; const char *string_to_search = "You will love the GLib implementation of regex"; g_autoptr(GMatchInfo) match_info = NULL; g_autoptr(GRegex) regex = NULL; regex = g_regex_new (regex_pattern, G_REGEX_DEFAULT, G_REGEX_MATCH_DEFAULT, NULL); g_assert (regex != NULL); if (g_regex_match (regex, string_to_search, G_REGEX_MATCH_DEFAULT, &match_info)) { int start_pos, end_pos; g_match_info_fetch_pos (match_info, 0, &start_pos, &end_pos); g_print ("Match successful! Overall pattern matches bytes %d to %d\n", start_pos, end_pos); } else { g_print ("No match!\n"); } The
constructor for GRegex includes two sets of bitmapped flags: *
[flags@GLib.RegexCompileFlags]—These flags control how GLib compiles the
regex. There are options for case sensitivity, multiline, ignoring
whitespace, etc. * [flags@GLib.RegexMatchFlags]—These flags control
GRegex’s matching behavior, such as anchoring and customizing definitions
for newline characters. Some regex patterns include backslash assertions,
such as \d (digit) or \D (non-digit). The regex pattern must escape those
backslashes. For example, the pattern "\\d\\D" matches a digit followed by
a non-digit. GLib’s implementation of pattern matching includes a
start_position argument for some of the match, replace, and split methods.
Specifying a start position provides flexibility when you want to ignore the
first n characters of a string, but want to incorporate backslash
assertions at character n - 1. For example, a database field contains
inconsistent spelling for a job title: healthcare provider and health-care provider. The database manager wants to make the spelling consistent by
adding a hyphen when it is missing. The following regex pattern tests for the
string care preceded by a non-word boundary character (instead of a hyphen)
and followed by a space. ``` { .c } const char *regex_pattern = "\Bcare\s";
`start_position` 6 in the string `healthcare` or `health-care`. ``` { .c }
const char *regex_pattern = "\\Bcare\\s"; const char *string_to_search =
"healthcare provider"; g_autoptr(GMatchInfo) match_info = NULL;
g_autoptr(GRegex) regex = NULL; regex = g_regex_new ( regex_pattern,
G_REGEX_DEFAULT, G_REGEX_MATCH_DEFAULT, NULL); g_assert (regex != NULL);
g_regex_match_full ( regex, string_to_search, -1, 6, // position of 'c' in
the test string. G_REGEX_MATCH_DEFAULT, &match_info, NULL); ``` The method
[method@GLib.Regex.match_full] (and other methods implementing `start_pos`)
allow for lookback before the start position to determine if the previous
character satisfies an assertion. Unless you set the
[flags@GLib.RegexCompileFlags.RAW] as one of the `GRegexCompileFlags`, all
the strings passed to `GRegex` methods 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. Regarding line endings, `\n` matches a `\n`
character, and `\r` matches a `\r` character. More generally, `\R` matches
all typical line endings: CR + LF (`\r\n`), 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),
and PS (paragraph separator, U+2029). The behaviour of the dot, circumflex,
and dollar metacharacters are affected by newline characters. By default,
`GRegex` matches any newline character matched by `\R`. You can limit the
matched newline characters by specifying the
[flags@GLib.RegexMatchFlags.NEWLINE_CR],
[flags@GLib.RegexMatchFlags.NEWLINE_LF], and
[flags@GLib.RegexMatchFlags.NEWLINE_CRLF] compile options, and with
[flags@GLib.RegexMatchFlags.NEWLINE_ANY],
[flags@GLib.RegexMatchFlags.NEWLINE_CR],
[flags@GLib.RegexMatchFlags.NEWLINE_LF] and
[flags@GLib.RegexMatchFlags.NEWLINE_CRLF] match options. These settings are
also relevant when compiling a pattern if
[flags@GLib.RegexCompileFlags.EXTENDED] is set and an unescaped `#` outside a
character class is encountered. This indicates a comment that lasts until
after the next newline. Because `GRegex` does not modify its internal state
between creation and destruction, you can create and modify the same `GRegex`
instance from different threads. In contrast, [struct@GLib.MatchInfo] is not
thread safe. The regular expression low-level functionalities are obtained
through the excellent [PCRE](http://www.pcre.org/) library written by Philip
Hazel.
#### Members
- **handleObj**
- **lib**
- **retainedCallbacks**
- **signalHandlerNames**
- **signalSetterHandlers**
#### Methods
- **GRegex** (`pattern = null, compile_options = null, match_options = null`)
> Compiles the regular expression to an internal form, and does the initial setup of the #GRegex structure.
- **@p** `pattern` is the regular expression.
- **@p** `compile_options` is compile options for the regular expression, or 0.
- **@p** `match_options` is match options for the regular expression, or 0.
- **toNativeHandle** (`Source`)
> Normalizes a constructor argument into a raw pointer carrier. Accepts a raw NativeHandle, a raw NativeBuffer returned from `fn.call(...)`, another generated wrapper exposing `handle()`, or null. Returns null when the argument carries no pointer.
- **@p** `Source` is the raw handle, raw buffer, wrapper, or null.
- **@r** `A` raw pointer carrier or null when no pointer is present.
- **getLib** ()
> Returns the opened native library for this generated wrapper.
- **@r** `The` opened native library.
- **handle** ()
> Returns the wrapped NativeHandle.
- **@r** `The` wrapped NativeHandle.
- **isNull** ()
> Returns true when the wrapped handle is null.
- **@r** `A` bool.
- **describe** ()
> Returns a small string for debugging generated wrappers.
- **@r** `A` string.
- **get\_capture\_count** ()
> Returns the number of capturing subpatterns in the pattern.
- **@r** `the` number of capturing subpatterns.
- **get\_compile\_flags** ()
> Returns the compile options that @regex was created with. Depending on the version of PCRE that is used, this may or may not include flags set by option expressions such as `(?i)` found at the top-level within the compiled pattern.
- **@r** `flags` from #GRegexCompileFlags.
- **get\_has\_cr\_or\_lf** ()
> Checks whether the pattern contains explicit CR or LF references.
- **@r** `%TRUE` if the pattern contains explicit CR or LF references.
- **get\_match\_flags** ()
> Returns the match options that @regex was created with.
- **@r** `flags` from #GRegexMatchFlags.
- **get\_max\_backref** ()
> Returns the number of the highest back reference in the pattern, or 0 if the pattern does not contain back references.
- **@r** `the` number of the highest back reference.
- **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.
- **@r** `the` number of characters in the longest lookbehind assertion..
- **get\_pattern** ()
> Gets the pattern string associated with @regex, i.e. a copy of the string passed to g_regex_new().
- **@r** `the` pattern of @regex.
- **get\_string\_number** (`string name`)
> Retrieves the number of the subexpression named @name.
- **@p** `name` is name of the subexpression.
- **@r** `The` number of the subexpression or -1 if @name does not exists.
- **match** (`string arg1String, string 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. Unless %G_REGEX_RAW is specified in the options, @string must be valid UTF-8. 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(). |[<!-- language="C" --> static void print_uppercase_words (const gchar *string) { // Print all uppercase-only words. GRegex *regex; GMatchInfo *match_info; regex = g_regex_new ("[A-Z]+", G_REGEX_DEFAULT, G_REGEX_MATCH_DEFAULT, 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.
- **@p** `string` is the string to scan for matches.
- **@p** `match_options` is match options.
- **@p** `match_info` is pointer to location where to store the #GMatchInfo, or %NULL if you do not need it.
- **@r** `%TRUE` is the string matched, %FALSE otherwise.
- **match\_all** (`string arg1String, string 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(). 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.
- **@p** `string` is the string to scan for matches.
- **@p** `match_options` is match options.
- **@p** `match_info` is pointer to location where to store the #GMatchInfo, or %NULL if you do not need it.
- **@r** `%TRUE` is the string matched, %FALSE otherwise.
- **match\_all\_full** (`string arg1String, int start_position, string match_options`)
> 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". Unless %G_REGEX_RAW is specified in the options, @string must be valid UTF-8. 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.
- **@p** `string` is the string to scan for matches.
- **@p** `string_len` is the length of @string, in bytes, or -1 if @string is nul-terminated.
- **@p** `start_position` is starting index of the string to match, in bytes.
- **@p** `match_options` is match options.
- **@p** `match_info` is pointer to location where to store the #GMatchInfo, or %NULL if you do not need it.
- **@r** `%TRUE` is the string matched, %FALSE otherwise.
- **match\_full** (`string arg1String, int start_position, string 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. 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". Unless %G_REGEX_RAW is specified in the options, @string must be valid UTF-8. 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(). |[<!-- language="C" --> 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]+", G_REGEX_DEFAULT, G_REGEX_MATCH_DEFAULT, 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); } } ]|
- **@p** `string` is the string to scan for matches.
- **@p** `string_len` is the length of @string, in bytes, or -1 if @string is nul-terminated.
- **@p** `start_position` is starting index of the string to match, in bytes.
- **@p** `match_options` is match options.
- **@p** `match_info` is pointer to location where to store the #GMatchInfo, or %NULL if you do not need it.
- **@r** `%TRUE` is the string matched, %FALSE otherwise.
- **ref** ()
> Increases reference count of @regex by 1.
- **@r** `@regex.`
- **replace** (`string arg1String, int start_position, string replacement, string match_options`)
> 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: - \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 strings 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".
- **@p** `string` is the string to perform matches against.
- **@p** `string_len` is the length of @string, in bytes, or -1 if @string is nul-terminated.
- **@p** `start_position` is starting index of the string to match, in bytes.
- **@p** `replacement` is text to replace each match with.
- **@p** `match_options` is options for the match.
- **@r** `a` newly allocated string containing the replacements.
- **replace\_eval** (`string arg1String, int start_position, string match_options, user_data`)
> 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: |[<!-- language="C" --> 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", G_REGEX_DEFAULT, G_REGEX_MATCH_DEFAULT, NULL); res = g_regex_replace_eval (reg, text, -1, 0, 0, eval_cb, h, NULL); g_hash_table_destroy (h); ... ]|
- **@p** `string` is string to perform matches against.
- **@p** `string_len` is the length of @string, in bytes, or -1 if @string is nul-terminated.
- **@p** `start_position` is starting index of the string to match, in bytes.
- **@p** `match_options` is options for the match.
- **@p** `eval` is a function to call for each match.
- **@p** `user_data` is user data to pass to the function.
- **@r** `a` newly allocated string containing the replacements.
- **replace\_literal** (`string arg1String, int start_position, string replacement, string match_options`)
> 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".
- **@p** `string` is the string to perform matches against.
- **@p** `string_len` is the length of @string, in bytes, or -1 if @string is nul-terminated.
- **@p** `start_position` is starting index of the string to match, in bytes.
- **@p** `replacement` is text to replace each match with.
- **@p** `match_options` is options for the match.
- **@r** `a` newly allocated string containing the replacements.
- **split** (`string arg1String, string 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 an 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".
- **@p** `string` is the string to split with the pattern.
- **@p** `match_options` is match time option flags.
- **@r** `a` %NULL-terminated gchar ** array. Free it using g_strfreev().
- **split\_full** (`string arg1String, int start_position, string match_options, int max_tokens`)
> 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 an 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".
- **@p** `string` is the string to split with the pattern.
- **@p** `string_len` is the length of @string, in bytes, or -1 if @string is nul-terminated.
- **@p** `start_position` is starting index of the string to match, in bytes.
- **@p** `match_options` is match time option flags.
- **@p** `max_tokens` is the maximum number of tokens to split @string into. If this is less than 1, the string is split completely.
- **@r** `a` %NULL-terminated gchar ** array. Free it using g_strfreev().
- **unref** ()
> Decreases reference count of @regex by 1. When reference count drops to zero, it frees all the memory associated with the regex structure.
- **@r** `None.`
