Regex

Object Hierarchy:

Description:

[ Compact ]
[ Version ( since = "2.14" ) ]
[ CCode ( ref_function = "g_regex_ref" , type_id = "G_TYPE_REGEX" , unref_function = "g_regex_unref" ) ]
public class Regex

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](man:pcrepattern(3)) for the syntax definition.

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.

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.

Namespace: GLib

Package: glib-2.0

Content:

Static methods:

public static bool check_replacement (string replacement, out bool has_references = null) throws RegexError
Checks whether replacement is a valid replacement string (see replace), i.
public static string escape_string (string str, int length = -1)
Escapes the special characters used for regular expressions in string, for instance "a.
public static bool match_simple (string pattern, string str, RegexCompileFlags compile_options = 0, RegexMatchFlags match_options = 0)
Scans for a match in string for pattern.
public static string[] split_simple (string pattern, string str, RegexCompileFlags compile_options = 0, RegexMatchFlags match_options = 0)
Breaks the string on the pattern, and returns an array of the tokens.

Creation methods:

public Regex (string pattern, RegexCompileFlags compile_options = 0, RegexMatchFlags match_options = 0) throws RegexError
Compiles the regular expression to an internal form, and does the initial setup of the Regex structure.

Methods:

public int get_capture_count ()
Returns the number of capturing subpatterns in the pattern.
public RegexCompileFlags get_compile_flags ()
Returns the compile options that this was created with.
public bool get_has_cr_or_lf ()
Checks whether the pattern contains explicit CR or LF references.
public RegexMatchFlags get_match_flags ()
Returns the match options that this was created with.
public int get_max_backref ()
Returns the number of the highest back reference in the pattern, or 0 if the pattern does not contain back references.
public int get_max_lookbehind ()
Gets the number of characters in the longest lookbehind assertion in the pattern.
public unowned string get_pattern ()
Gets the pattern string associated with this , i.
public int get_string_number (string name)
Retrieves the number of the subexpression named name.
public bool match (string str, RegexMatchFlags match_options = 0, out MatchInfo match_info = null)
Scans for a match in string for the pattern in this.
public bool match_all (string str, RegexMatchFlags match_options = 0, out MatchInfo match_info = null)
Using the standard algorithm for regular expression matching only the longest match in the string is retrieved.
public bool match_all_full (string str, ssize_t string_len = -1, int start_position = 0, RegexMatchFlags match_options = 0, out MatchInfo match_info = null) throws RegexError
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.
public bool match_full (string str, ssize_t string_len = -1, int start_position = 0, RegexMatchFlags match_options = 0, out MatchInfo match_info = null) throws RegexError
Scans for a match in string for the pattern in this.
public string replace (string str, ssize_t string_len, int start_position, string replacement, RegexMatchFlags match_options = 0) throws RegexError
Replaces all occurrences of the pattern in this with the replacement text.
public string replace_eval (string str, ssize_t string_len, int start_position, RegexMatchFlags match_options, RegexEvalCallback eval) throws RegexError
Replaces occurrences of the pattern in regex with the output of eval for that occurrence.
public string replace_literal (string str, ssize_t string_len, int start_position, string replacement, RegexMatchFlags match_options = 0) throws RegexError
Replaces all occurrences of the pattern in this with the replacement text.
public string[] split (string str, RegexMatchFlags match_options = 0)
Breaks the string on the pattern, and returns an array of the tokens.
public string[] split_full (string str, ssize_t string_len = -1, int start_position = 0, RegexMatchFlags match_options = 0, int max_tokens = 0) throws RegexError
Breaks the string on the pattern, and returns an array of the tokens.