regex package:gi-glib

A GRegex is the "compiled" form of a regular expression pattern. GRegex implements regular expression pattern matching using syntax and semantics similar to Perl regular expression. See the PCRE documentation) for the syntax definition. Some functions accept a startPosition argument, setting it differs from just passing over a shortened string and setting RegexMatchFlagsNotbol 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 startPosition 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 RegexCompileFlagsRaw 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 RegexCompileFlagsRaw 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. Creating and manipulating the same GRegex structure from different threads is not a problem as GRegex does not modify its internal state between creation and destruction, on the other hand GMatchInfo is not threadsafe. The regular expressions low-level functionalities are obtained through the excellent PCRE library written by Philip Hazel. Since: 2.14

Memory-managed wrapper type.

Checks whether replacement is a valid replacement string (see regexReplace), i.e. that all escape sequences in it are valid. If hasReferences is not Nothing 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 MatchInfo object. Since: 2.14

No description available in the introspection data.

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

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

Returns the number of capturing subpatterns in the pattern. Since: 2.14

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. Since: 2.26

Checks whether the pattern contains explicit CR or LF references. Since: 2.34

Returns the match options that regex was created with. Since: 2.26

Returns the number of the highest back reference in the pattern, or 0 if the pattern does not contain back references. Since: 2.14

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

Gets the pattern string associated with regex, i.e. a copy of the string passed to regexNew. Since: 2.14

Retrieves the number of the subexpression named name. Since: 2.14

Scans for a match in string for the pattern in regex. The matchOptions are combined with the match options specified when the regex structure was created, letting you have more flexibility in reusing Regex structures. Unless RegexCompileFlagsRaw is specified in the options, string must be valid UTF-8. A MatchInfo structure, used to get information on the match, is stored in matchInfo if not Nothing. Note that if matchInfo is not Nothing 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 matchInfoNext.

C code

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 MatchInfo internally. If you use any MatchInfo method (except matchInfoFree) after freeing or modifying string then the behaviour is undefined. Since: 2.14

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 regexMatchAllFull. A MatchInfo structure, used to get information on the match, is stored in matchInfo if not Nothing. Note that if matchInfo is not Nothing 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 MatchInfo internally. If you use any MatchInfo method (except matchInfoFree) after freeing or modifying string then the behaviour is undefined. Since: 2.14

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 matchInfoGetMatchCount. To obtain the matched strings and their position you can use, respectively, matchInfoFetch and matchInfoFetchPos. 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 startPosition differs from just passing over a shortened string and setting RegexMatchFlagsNotbol in the case of a pattern that begins with any kind of lookbehind assertion, such as "\b". Unless RegexCompileFlagsRaw is specified in the options, string must be valid UTF-8. A MatchInfo structure, used to get information on the match, is stored in matchInfo if not Nothing. Note that if matchInfo is not Nothing 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 MatchInfo internally. If you use any MatchInfo method (except matchInfoFree) after freeing or modifying string then the behaviour is undefined. Since: 2.14

Scans for a match in string for the pattern in regex. The matchOptions are combined with the match options specified when the regex structure was created, letting you have more flexibility in reusing Regex structures. Setting startPosition differs from just passing over a shortened string and setting RegexMatchFlagsNotbol in the case of a pattern that begins with any kind of lookbehind assertion, such as "\b". Unless RegexCompileFlagsRaw is specified in the options, string must be valid UTF-8. A MatchInfo structure, used to get information on the match, is stored in matchInfo if not Nothing. Note that if matchInfo is not Nothing 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 MatchInfo internally. If you use any MatchInfo method (except matchInfoFree) 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 matchInfoNext.

C code

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);
}
}

Since: 2.14

Scans for a match in string for pattern. This function is equivalent to regexMatch but it does not require to compile the pattern with regexNew, 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 regexNew and then use regexMatch. Since: 2.14

Compiles the regular expression to an internal form, and does the initial setup of the Regex structure. Since: 2.14

Increases reference count of regex by 1. Since: 2.14

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 regexReplaceLiteral. The replacement string must be UTF-8 encoded even if RegexCompileFlagsRaw was passed to regexNew. If you want to use not UTF-8 encoded strings you can use regexReplaceLiteral. Setting startPosition differs from just passing over a shortened string and setting RegexMatchFlagsNotbol in the case of a pattern that begins with any kind of lookbehind assertion, such as "\b". Since: 2.14

Replaces occurrences of the pattern in regex with the output of eval for that occurrence. Setting startPosition differs from just passing over a shortened string and setting RegexMatchFlagsNotbol in the case of a pattern that begins with any kind of lookbehind assertion, such as "\b". The following example uses regexReplaceEval to replace multiple strings at once:

C code

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);

...

Since: 2.14

Replaces all occurrences of the pattern in regex with the replacement text. replacement is replaced literally, to include backreferences use regexReplace. Setting startPosition differs from just passing over a shortened string and setting RegexMatchFlagsNotbol in the case of a pattern that begins with any kind of lookbehind assertion, such as "\b". Since: 2.14