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 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 {

GRegex* getRegexStruct(bool transferOwnership);

void* getStruct();

this(GRegex* gRegex, bool ownedRef);

~this();

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

int getCaptureCount();

GRegexCompileFlags getCompileFlags();

bool getHasCrOrLf();

GRegexMatchFlags getMatchFlags();

int getMaxBackref();

int getMaxLookbehind();

string getPattern();

int getStringNumber(string name);

bool match(string string_, GRegexMatchFlags matchOptions, MatchInfo matchInfo);

bool matchAll(string string_, GRegexMatchFlags matchOptions, MatchInfo matchInfo);

bool matchAllFull(string string_, int startPosition, GRegexMatchFlags matchOptions, MatchInfo matchInfo);

bool matchFull(string string_, int startPosition, GRegexMatchFlags matchOptions, MatchInfo matchInfo);

alias doref = ref_;

Regex ref_();

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

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

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

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

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

void unref();

static bool checkReplacement(string replacement, bool hasReferences);

static GQuark errorQuark();

static string escapeNul(string string_, int length);

static string escapeString(string string_);

static bool matchSimple(string pattern, string string_, GRegexCompileFlags compileOptions, GRegexMatchFlags matchOptions);

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

}

Constructors

this this(GRegex* gRegex, bool ownedRef): 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.

Destructor

~this ~this(): Undocumented in source.

Members

Aliases

doref alias doref = ref_: Undocumented in source.

Functions

getCaptureCount int getCaptureCount(): Returns the number of capturing subpatterns in the pattern.
getCompileFlags GRegexCompileFlags getCompileFlags(): Returns the compile options that @regex was created with.
getHasCrOrLf bool getHasCrOrLf(): Checks whether the pattern contains explicit CR or LF references.
getMatchFlags GRegexMatchFlags getMatchFlags(): Returns the match options that @regex was created with.
getMaxBackref int getMaxBackref(): Returns the number of the highest back reference in the pattern, or 0 if the pattern does not contain back references.
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.
getPattern string getPattern(): Gets the pattern string associated with @regex, i.e. a copy of the string passed to g_regex_new().
getRegexStruct GRegex* getRegexStruct(bool transferOwnership): Get the main Gtk struct
getStringNumber int getStringNumber(string name): Retrieves the number of the subexpression named @name.
getStruct void* getStruct(): the main Gtk struct as a void*
match bool 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.
matchAll bool 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().
matchAllFull bool 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>".
matchFull bool 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.
ref_ Regex ref_(): Increases reference count of @regex by 1.
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 '\\\\'.
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.
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().
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.
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.
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.

Static functions

checkReplacement bool checkReplacement(string replacement, bool hasReferences): Checks whether @replacement is a valid replacement string (see g_regex_replace()), i.e. that all escape sequences in it are valid.
errorQuark GQuark errorQuark()
escapeNul string escapeNul(string string_, int length): Escapes the nul characters in @string to "\x00". It can be used to compile a regex with embedded nul characters.
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.
matchSimple bool matchSimple(string pattern, string string_, GRegexCompileFlags compileOptions, GRegexMatchFlags matchOptions): Scans for a match in @string for @pattern.
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.

Variables

gRegex GRegex* gRegex;: the main Gtk struct
ownedRef bool ownedRef;: Undocumented in source.