GLib.Regex

Fields

None

Methods

class check_replacement (replacement)
class error_quark ()
class escape_nul (string, length)
class escape_string (string)
class match_simple (pattern, string, compile_options, match_options)
class new (pattern, compile_options, match_options)
class split_simple (pattern, string, compile_options, match_options)
  get_capture_count ()
  get_compile_flags ()
  get_has_cr_or_lf ()
  get_match_flags ()
  get_max_backref ()
  get_max_lookbehind ()
  get_pattern ()
  get_string_number (name)
  match (string, match_options)
  match_all (string, match_options)
  match_all_full (string, start_position, match_options)
  match_full (string, start_position, match_options)
  ref ()
  replace (string, start_position, replacement, match_options)
  replace_literal (string, start_position, replacement, match_options)
  split (string, match_options)
  split_full (string, start_position, match_options, max_tokens)
  unref ()

Details

class GLib.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 GLib.RegexMatchFlags.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 GLib.RegexCompileFlags.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 GLib.RegexCompileFlags.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 GLib.RegexCompileFlags.NEWLINE_CR, GLib.RegexCompileFlags.NEWLINE_LF and GLib.RegexCompileFlags.NEWLINE_CRLF compile options, and with GLib.RegexMatchFlags.NEWLINE_ANY, GLib.RegexMatchFlags.NEWLINE_CR, GLib.RegexMatchFlags.NEWLINE_LF and GLib.RegexMatchFlags.NEWLINE_CRLF match options. These settings are also relevant when compiling a pattern if 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.

When setting the GLib.RegexCompileFlags.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 GLib.Regex structure from different threads is not a problem as GLib.Regex does not modify its internal state between creation and destruction, on the other hand GLib.MatchInfo is not threadsafe.

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

New in version 2.14.

classmethod check_replacement(replacement)[source]
Parameters:replacement (str) – the replacement string
Raises:GLib.Error
Returns:whether replacement is a valid replacement string
has_references:location to store information about references in replacement or None
Return type:(bool, has_references: bool)

Checks whether replacement is a valid replacement string (see GLib.Regex.replace()), i.e. that all escape sequences in it are valid.

If has_references is not None 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 GLib.MatchInfo object.

New in version 2.14.

classmethod error_quark()[source]
Return type:int
classmethod escape_nul(string, length)[source]
Parameters:
  • string (str) – the string to escape
  • length (int) – the length of string
Returns:

a newly-allocated escaped string

Return type:

str

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.

New in version 2.30.

classmethod escape_string(string)[source]
Parameters:string ([str]) – the string to escape
Returns:a newly-allocated escaped string
Return type:str

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.

New in version 2.14.

classmethod match_simple(pattern, string, compile_options, match_options)[source]
Parameters:
  • pattern (str) – the regular expression
  • string (str) – the string to scan for matches
  • compile_options (GLib.RegexCompileFlags) – compile options for the regular expression, or 0
  • match_options (GLib.RegexMatchFlags) – match options, or 0
Returns:

True if the string matched, False otherwise

Return type:

bool

Scans for a match in string for pattern.

This function is equivalent to GLib.Regex.match() but it does not require to compile the pattern with GLib.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 GLib.Regex.new() and then use GLib.Regex.match().

New in version 2.14.

classmethod new(pattern, compile_options, match_options)[source]
Parameters:
Raises:

GLib.Error

Returns:

a GLib.Regex structure or None if an error occured. Call GLib.Regex.unref() when you are done with it

Return type:

GLib.Regex or None

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

New in version 2.14.

classmethod split_simple(pattern, string, compile_options, match_options)[source]
Parameters:
  • pattern (str) – the regular expression
  • string (str) – the string to scan for matches
  • compile_options (GLib.RegexCompileFlags) – compile options for the regular expression, or 0
  • match_options (GLib.RegexMatchFlags) – match options, or 0
Returns:

a None-terminated array of strings. Free it using GLib.strfreev()

Return type:

[str]

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 GLib.Regex.split() but it does not require to compile the pattern with GLib.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 GLib.Regex.new() and then use GLib.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”.

New in version 2.14.

get_capture_count()[source]
Returns:the number of capturing subpatterns
Return type:int

Returns the number of capturing subpatterns in the pattern.

New in version 2.14.

get_compile_flags()[source]
Returns:flags from GLib.RegexCompileFlags
Return type:GLib.RegexCompileFlags

Returns the compile options that self 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.

New in version 2.26.

get_has_cr_or_lf()[source]
Returns:True if the pattern contains explicit CR or LF references
Return type:bool

Checks whether the pattern contains explicit CR or LF references.

New in version 2.34.

get_match_flags()[source]
Returns:flags from GLib.RegexMatchFlags
Return type:GLib.RegexMatchFlags

Returns the match options that self was created with.

New in version 2.26.

get_max_backref()[source]
Returns:the number of the highest back reference
Return type:int

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

New in version 2.14.

get_max_lookbehind()[source]
Returns:the number of characters in the longest lookbehind assertion.
Return type:int

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.

New in version 2.38.

get_pattern()[source]
Returns:the pattern of self
Return type:str

Gets the pattern string associated with self, i.e. a copy of the string passed to GLib.Regex.new().

New in version 2.14.

get_string_number(name)[source]
Parameters:name (str) – name of the subexpression
Returns:The number of the subexpression or -1 if name does not exists
Return type:int

Retrieves the number of the subexpression named name.

New in version 2.14.

match(string, match_options)[source]
Parameters:
Returns:

True is the string matched, False otherwise

match_info:pointer to location where to store the GLib.MatchInfo, or None if you do not need it

Return type:

(bool, match_info: GLib.MatchInfo)

Scans for a match in string for the pattern in self. The match_options are combined with the match options specified when the self structure was created, letting you have more flexibility in reusing GLib.Regex structures.

Unless GLib.RegexCompileFlags.RAW is specified in the options, string must be valid UTF-8.

A GLib.MatchInfo structure, used to get information on the match, is stored in match_info if not None. Note that if match_info is not None 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 GLib.MatchInfo.next().

static void
print_uppercase_words (const gchar *string)
{
  // Print all uppercase-only words.
  GRegex *regex;
  GMatchInfo *match_info;

  regex = g_regex_new ("[A-Z]+", 0, 0, 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 GLib.MatchInfo internally. If you use any GLib.MatchInfo method (except GLib.MatchInfo.free()) after freeing or modifying string then the behaviour is undefined.

New in version 2.14.

match_all(string, match_options)[source]
Parameters:
Returns:

True is the string matched, False otherwise

match_info:pointer to location where to store the GLib.MatchInfo, or None if you do not need it

Return type:

(bool, match_info: GLib.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 GLib.Regex.match_all_full().

A GLib.MatchInfo structure, used to get information on the match, is stored in match_info if not None. Note that if match_info is not None 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 GLib.MatchInfo internally. If you use any GLib.MatchInfo method (except GLib.MatchInfo.free()) after freeing or modifying string then the behaviour is undefined.

New in version 2.14.

match_all_full(string, start_position, match_options)[source]
Parameters:
  • string ([str]) – the string to scan for matches
  • start_position (int) – starting index of the string to match, in bytes
  • match_options (GLib.RegexMatchFlags) – match options
Raises:

GLib.Error

Returns:

True is the string matched, False otherwise

match_info:pointer to location where to store the GLib.MatchInfo, or None if you do not need it

Return type:

(bool, match_info: GLib.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 GLib.MatchInfo.get_match_count(). To obtain the matched strings and their position you can use, respectively, GLib.MatchInfo.fetch() and GLib.MatchInfo.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 GLib.RegexMatchFlags.NOTBOL in the case of a pattern that begins with any kind of lookbehind assertion, such as “\b”.

Unless GLib.RegexCompileFlags.RAW is specified in the options, string must be valid UTF-8.

A GLib.MatchInfo structure, used to get information on the match, is stored in match_info if not None. Note that if match_info is not None 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 GLib.MatchInfo internally. If you use any GLib.MatchInfo method (except GLib.MatchInfo.free()) after freeing or modifying string then the behaviour is undefined.

New in version 2.14.

match_full(string, start_position, match_options)[source]
Parameters:
  • string ([str]) – the string to scan for matches
  • start_position (int) – starting index of the string to match, in bytes
  • match_options (GLib.RegexMatchFlags) – match options
Raises:

GLib.Error

Returns:

True is the string matched, False otherwise

match_info:pointer to location where to store the GLib.MatchInfo, or None if you do not need it

Return type:

(bool, match_info: GLib.MatchInfo)

Scans for a match in string for the pattern in self. The match_options are combined with the match options specified when the self structure was created, letting you have more flexibility in reusing GLib.Regex structures.

Setting start_position differs from just passing over a shortened string and setting GLib.RegexMatchFlags.NOTBOL in the case of a pattern that begins with any kind of lookbehind assertion, such as “\b”.

Unless GLib.RegexCompileFlags.RAW is specified in the options, string must be valid UTF-8.

A GLib.MatchInfo structure, used to get information on the match, is stored in match_info if not None. Note that if match_info is not None 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 GLib.MatchInfo internally. If you use any GLib.MatchInfo method (except GLib.MatchInfo.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 GLib.MatchInfo.next().

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]+", 0, 0, 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);
    }
}

New in version 2.14.

ref()[source]
Returns:self
Return type:GLib.Regex

Increases reference count of self by 1.

New in version 2.14.

replace(string, start_position, replacement, match_options)[source]
Parameters:
  • string ([str]) – the string to perform matches against
  • start_position (int) – starting index of the string to match, in bytes
  • replacement (str) – text to replace each match with
  • match_options (GLib.RegexMatchFlags) – options for the match
Raises:

GLib.Error

Returns:

a newly allocated string containing the replacements

Return type:

str

Replaces all occurrences of the pattern in self 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 GLib.Regex.replace_literal().

The replacement string must be UTF-8 encoded even if GLib.RegexCompileFlags.RAW was passed to GLib.Regex.new(). If you want to use not UTF-8 encoded stings you can use GLib.Regex.replace_literal().

Setting start_position differs from just passing over a shortened string and setting GLib.RegexMatchFlags.NOTBOL in the case of a pattern that begins with any kind of lookbehind assertion, such as “\b”.

New in version 2.14.

replace_literal(string, start_position, replacement, match_options)[source]
Parameters:
  • string ([str]) – the string to perform matches against
  • start_position (int) – starting index of the string to match, in bytes
  • replacement (str) – text to replace each match with
  • match_options (GLib.RegexMatchFlags) – options for the match
Raises:

GLib.Error

Returns:

a newly allocated string containing the replacements

Return type:

str

Replaces all occurrences of the pattern in self with the replacement text. replacement is replaced literally, to include backreferences use GLib.Regex.replace().

Setting start_position differs from just passing over a shortened string and setting GLib.RegexMatchFlags.NOTBOL in the case of a pattern that begins with any kind of lookbehind assertion, such as “\b”.

New in version 2.14.

split(string, match_options)[source]
Parameters:
  • string (str) – the string to split with the pattern
  • match_options (GLib.RegexMatchFlags) – match time option flags
Returns:

a None-terminated str ** array. Free it using GLib.strfreev()

Return type:

[str]

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”.

New in version 2.14.

split_full(string, start_position, match_options, max_tokens)[source]
Parameters:
  • string ([str]) – the string to split with the pattern
  • start_position (int) – starting index of the string to match, in bytes
  • match_options (GLib.RegexMatchFlags) – match time option flags
  • max_tokens (int) – the maximum number of tokens to split string into. If this is less than 1, the string is split completely
Raises:

GLib.Error

Returns:

a None-terminated str ** array. Free it using GLib.strfreev()

Return type:

[str]

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 GLib.RegexMatchFlags.NOTBOL in the case of a pattern that begins with any kind of lookbehind assertion, such as “\b”.

New in version 2.14.

unref()[source]

Decreases reference count of self by 1. When reference count drops to zero, it frees all the memory associated with the regex structure.

New in version 2.14.