Regex

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

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

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

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

The behaviour of the dot, circumflex, and dollar metacharacters are affected by newline characters, the default is to recognize any newline character (the same characters recognized by "\R"). This can be changed with G_REGEX_NEWLINE_CR, G_REGEX_NEWLINE_LF and G_REGEX_NEWLINE_CRLF compile options, and with G_REGEX_MATCH_NEWLINE_ANY, G_REGEX_MATCH_NEWLINE_CR, G_REGEX_MATCH_NEWLINE_LF and G_REGEX_MATCH_NEWLINE_CRLF match options. These settings are also relevant when compiling a pattern if G_REGEX_EXTENDED is set, and an unescaped "#" outside a character class is encountered. This indicates a comment that lasts until after the next newline.

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

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

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

class Regex {}

Constructors

this
this(GRegex* gRegex)

Sets our main struct and passes it to the parent class

this
this(string pattern, GRegexCompileFlags compileOptions, GRegexMatchFlags matchOptions)

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

Destructor

~this
~this()
Undocumented in source.

Members

Functions

doref
Regex doref()

Increases reference count of regex by 1. Since 2.14

getCaptureCount
int getCaptureCount()

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

getCompileFlags
GRegexCompileFlags getCompileFlags()

Returns the compile options that regex was created with. Since 2.26

getHasCrOrLf
int getHasCrOrLf()

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

getMatchFlags
GRegexMatchFlags getMatchFlags()

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

getMaxBackref
int getMaxBackref()

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

getMaxLookbehind
int getMaxLookbehind()

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

getPattern
string getPattern()

Gets the pattern string associated with regex, i.e. a copy of the string passed to g_regex_new(). Since 2.14

getRegexStruct
GRegex* getRegexStruct()

Get the main Gtk struct

getStringNumber
int getStringNumber(string name)

Retrieves the number of the subexpression named name. Since 2.14

getStruct
void* getStruct()

the main Gtk struct as a void*

match
int match(string string, GRegexMatchFlags matchOptions, MatchInfo matchInfo)

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(). 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

matchAll
int matchAll(string string, GRegexMatchFlags matchOptions, MatchInfo matchInfo)

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

matchAllFull
int matchAllFull(string string, int startPosition, GRegexMatchFlags matchOptions, MatchInfo matchInfo)

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

matchFull
int matchFull(string string, int startPosition, GRegexMatchFlags matchOptions, MatchInfo matchInfo)

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(). Since 2.14

replace
string replace(string string, int startPosition, string replacement, GRegexMatchFlags matchOptions)

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 '\\'. Since 2.14

replaceEval
string replaceEval(string string, int startPosition, GRegexMatchFlags matchOptions, GRegexEvalCallback eval, void* userData)

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 Since 2.14

replaceLiteral
string replaceLiteral(string string, int startPosition, string replacement, GRegexMatchFlags matchOptions)

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

split
string[] split(string string, GRegexMatchFlags matchOptions)

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

splitFull
string[] splitFull(string string, int startPosition, GRegexMatchFlags matchOptions, int maxTokens)

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

unref
void unref()

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

Static functions

checkReplacement
int checkReplacement(string replacement, int hasReferences)

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

escapeNul
string escapeNul(string string)

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

escapeString
string escapeString(string string)

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

matchSimple
int matchSimple(string pattern, string string, GRegexCompileFlags compileOptions, GRegexMatchFlags matchOptions)

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

splitSimple
string[] splitSimple(string pattern, string string, GRegexCompileFlags compileOptions, GRegexMatchFlags matchOptions)

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

Variables

gRegex
GRegex* gRegex;

the main Gtk struct

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