pub struct Regex { /* private fields */ }Expand description
A GRegex is a compiled form of a regular expression.
After instantiating a GRegex, you can use its methods to find matches
in a string, replace matches within a string, or split the string at matches.
GRegex implements regular expression pattern matching using syntax and
semantics (such as character classes, quantifiers, and capture groups)
similar to Perl regular expression. See the
PCRE documentation for details.
A typical scenario for regex pattern matching is to check if a string matches a pattern. The following statements implement this scenario.
⚠️ The following code is in { .c } ⚠️
const char *regex_pattern = ".*GLib.*";
const char *string_to_search = "You will love the GLib implementation of regex";
g_autoptr(GMatchInfo) match_info = NULL;
g_autoptr(GRegex) regex = NULL;
regex = g_regex_new (regex_pattern, G_REGEX_DEFAULT, G_REGEX_MATCH_DEFAULT, NULL);
g_assert (regex != NULL);
if (g_regex_match (regex, string_to_search, G_REGEX_MATCH_DEFAULT, &match_info))
{
int start_pos, end_pos;
g_match_info_fetch_pos (match_info, 0, &start_pos, &end_pos);
g_print ("Match successful! Overall pattern matches bytes %d to %d\n", start_pos, end_pos);
}
else
{
g_print ("No match!\n");
}The constructor for GRegex includes two sets of bitmapped flags:
RegexCompileFlags—These flags control how GLib compiles the regex. There are options for case sensitivity, multiline, ignoring whitespace, etc.RegexMatchFlags—These flags controlGRegex’s matching behavior, such as anchoring and customizing definitions for newline characters.
Some regex patterns include backslash assertions, such as \d (digit) or
\D (non-digit). The regex pattern must escape those backslashes. For
example, the pattern "\\d\\D" matches a digit followed by a non-digit.
GLib’s implementation of pattern matching includes a start_position
argument for some of the match, replace, and split methods. Specifying
a start position provides flexibility when you want to ignore the first
n characters of a string, but want to incorporate backslash assertions
at character n - 1. For example, a database field contains inconsistent
spelling for a job title: healthcare provider and health-care provider.
The database manager wants to make the spelling consistent by adding a
hyphen when it is missing. The following regex pattern tests for the string
care preceded by a non-word boundary character (instead of a hyphen)
and followed by a space.
⚠️ The following code is in { .c } ⚠️
const char *regex_pattern = "\\Bcare\\s";An efficient way to match with this pattern is to start examining at
start_position 6 in the string healthcare or health-care.
⚠️ The following code is in { .c } ⚠️
const char *regex_pattern = "\\Bcare\\s";
const char *string_to_search = "healthcare provider";
g_autoptr(GMatchInfo) match_info = NULL;
g_autoptr(GRegex) regex = NULL;
regex = g_regex_new (
regex_pattern,
G_REGEX_DEFAULT,
G_REGEX_MATCH_DEFAULT,
NULL);
g_assert (regex != NULL);
g_regex_match_full (
regex,
string_to_search,
-1,
6, // position of 'c' in the test string.
G_REGEX_MATCH_DEFAULT,
&match_info,
NULL);The method match_full() (and other methods implementing
start_pos) allow for lookback before the start position to determine if
the previous character satisfies an assertion.
Unless you set the [flags@GLib.RegexCompileFlags.RAW] as one of
the GRegexCompileFlags, all the strings passed to GRegex methods 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.
Regarding line endings, \n matches a \n character, and \r matches
a \r character. More generally, \R matches all typical line endings:
CR + LF (\r\n), 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), and PS (paragraph
separator, U+2029).
The behaviour of the dot, circumflex, and dollar metacharacters are
affected by newline characters. By default, GRegex matches any newline
character matched by \R. You can limit the matched newline characters by
specifying the [flags@GLib.RegexMatchFlags.NEWLINE_CR],
[flags@GLib.RegexMatchFlags.NEWLINE_LF], and
[flags@GLib.RegexMatchFlags.NEWLINE_CRLF] compile options, and
with [flags@GLib.RegexMatchFlags.NEWLINE_ANY],
[flags@GLib.RegexMatchFlags.NEWLINE_CR],
[flags@GLib.RegexMatchFlags.NEWLINE_LF] and
[flags@GLib.RegexMatchFlags.NEWLINE_CRLF] match options.
These settings are also relevant when compiling a pattern if
[flags@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.
Because GRegex does not modify its internal state between creation and
destruction, you can create and modify the same GRegex instance from
different threads. In contrast, MatchInfo is not thread safe.
The regular expression low-level functionalities are obtained through the excellent PCRE library written by Philip Hazel.
GLib type: Shared boxed type with reference counted clone semantics.
Implementations§
Source§impl Regex
impl Regex
Sourcepub fn new(
pattern: &str,
compile_options: RegexCompileFlags,
match_options: RegexMatchFlags,
) -> Result<Option<Regex>, Error>
pub fn new( pattern: &str, compile_options: RegexCompileFlags, match_options: RegexMatchFlags, ) -> Result<Option<Regex>, Error>
Compiles the regular expression to an internal form, and does the initial setup of the #GRegex structure.
§pattern
the regular expression
§compile_options
compile options for the regular expression, or 0
§match_options
match options for the regular expression, or 0
§Returns
a #GRegex structure or None if an error occurred. Call
g_regex_unref() when you are done with it
Sourcepub fn capture_count(&self) -> i32
pub fn capture_count(&self) -> i32
Returns the number of capturing subpatterns in the pattern.
§Returns
the number of capturing subpatterns
Sourcepub fn compile_flags(&self) -> RegexCompileFlags
pub fn compile_flags(&self) -> 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.
§Returns
flags from #GRegexCompileFlags
Sourcepub fn has_cr_or_lf(&self) -> bool
pub fn has_cr_or_lf(&self) -> bool
Sourcepub fn match_flags(&self) -> RegexMatchFlags
pub fn match_flags(&self) -> RegexMatchFlags
Sourcepub fn max_backref(&self) -> i32
pub fn max_backref(&self) -> i32
Returns the number of the highest back reference in the pattern, or 0 if the pattern does not contain back references.
§Returns
the number of the highest back reference
Sourcepub fn max_lookbehind(&self) -> i32
pub fn max_lookbehind(&self) -> i32
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.
§Returns
the number of characters in the longest lookbehind assertion.
Source§impl Regex
impl Regex
Sourcepub fn string_number(&self, name: impl IntoGStr) -> i32
pub fn string_number(&self, name: impl IntoGStr) -> i32
Sourcepub fn escape_nul(string: impl IntoGStr) -> GString
pub fn escape_nul(string: impl IntoGStr) -> GString
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.
§string
the string to escape
§length
the length of @string
§Returns
a newly-allocated escaped string
Sourcepub fn escape_string(string: impl IntoGStr) -> GString
pub fn escape_string(string: impl IntoGStr) -> GString
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.
§string
the string to escape
§length
the length of @string, in bytes, or -1 if @string is nul-terminated
§Returns
a newly-allocated escaped string
Sourcepub fn check_replacement(replacement: impl IntoGStr) -> Result<bool, Error>
pub fn check_replacement(replacement: impl IntoGStr) -> Result<bool, Error>
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 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 #GMatchInfo object.
§replacement
the replacement string
§Returns
whether @replacement is a valid replacement string
§has_references
location to store information about
references in @replacement or None
Sourcepub fn match_simple(
pattern: impl IntoGStr,
string: impl IntoGStr,
compile_options: RegexCompileFlags,
match_options: RegexMatchFlags,
) -> bool
pub fn match_simple( pattern: impl IntoGStr, string: impl IntoGStr, compile_options: RegexCompileFlags, match_options: RegexMatchFlags, ) -> bool
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().
§pattern
the regular expression
§string
the string to scan for matches
§compile_options
compile options for the regular expression, or 0
§match_options
match options, or 0
§Returns
Sourcepub fn replace(
&self,
string: impl IntoGStr,
start_position: i32,
replacement: impl IntoGStr,
match_options: RegexMatchFlags,
) -> Result<GString, Error>
pub fn replace( &self, string: impl IntoGStr, start_position: i32, replacement: impl IntoGStr, match_options: RegexMatchFlags, ) -> Result<GString, Error>
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 g_regex_replace_literal().
The @replacement string must be UTF-8 encoded even if RegexCompileFlags::RAW was
passed to g_regex_new(). If you want to use not UTF-8 encoded strings
you can use g_regex_replace_literal().
Setting @start_position differs from just passing over a shortened
string and setting RegexMatchFlags::NOTBOL in the case of a pattern that
begins with any kind of lookbehind assertion, such as “\b”.
§string
the string to perform matches against
§start_position
starting index of the string to match, in bytes
§replacement
text to replace each match with
§match_options
options for the match
§Returns
a newly allocated string containing the replacements
Sourcepub fn match_all<'input>(
&self,
string: &'input GStr,
match_options: RegexMatchFlags,
) -> Option<MatchInfo<'input>>
pub fn match_all<'input>( &self, string: &'input GStr, match_options: RegexMatchFlags, ) -> Option<MatchInfo<'input>>
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 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 #GMatchInfo internally. If you use any #GMatchInfo method (except g_match_info_free()) after freeing or modifying @string then the behaviour is undefined.
§string
the string to scan for matches
§match_options
match options
§Returns
true is the string matched, false otherwise
§match_info
pointer to location where to store
the #GMatchInfo, or None if you do not need it
Sourcepub fn match_all_full<'input>(
&self,
string: &'input GStr,
start_position: i32,
match_options: RegexMatchFlags,
) -> Result<MatchInfo<'input>, Error>
pub fn match_all_full<'input>( &self, string: &'input GStr, start_position: i32, match_options: RegexMatchFlags, ) -> Result<MatchInfo<'input>, Error>
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 RegexMatchFlags::NOTBOL in the case of a pattern
that begins with any kind of lookbehind assertion, such as “\b”.
Unless RegexCompileFlags::RAW is specified in the options, @string must be valid UTF-8.
A #GMatchInfo 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 #GMatchInfo internally. If you use any #GMatchInfo method (except g_match_info_free()) after freeing or modifying @string then the behaviour is undefined.
§string
the string to scan for matches
§start_position
starting index of the string to match, in bytes
§match_options
match options
§Returns
true is the string matched, false otherwise
§match_info
pointer to location where to store
the #GMatchInfo, or None if you do not need it
Sourcepub fn match_<'input>(
&self,
string: &'input GStr,
match_options: RegexMatchFlags,
) -> Option<MatchInfo<'input>>
pub fn match_<'input>( &self, string: &'input GStr, match_options: RegexMatchFlags, ) -> Option<MatchInfo<'input>>
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 #GRegex structures.
Unless RegexCompileFlags::RAW is specified in the options, @string must be valid UTF-8.
A #GMatchInfo 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 g_match_info_next().
⚠️ The following code is in C ⚠️
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 #GMatchInfo internally. If you use any #GMatchInfo method (except g_match_info_free()) after freeing or modifying @string then the behaviour is undefined.
§string
the string to scan for matches
§match_options
match options
§Returns
true is the string matched, false otherwise
§match_info
pointer to location where to store
the #GMatchInfo, or None if you do not need it
Sourcepub fn match_full<'input>(
&self,
string: &'input GStr,
start_position: i32,
match_options: RegexMatchFlags,
) -> Result<MatchInfo<'input>, Error>
pub fn match_full<'input>( &self, string: &'input GStr, start_position: i32, match_options: RegexMatchFlags, ) -> Result<MatchInfo<'input>, Error>
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 #GRegex structures.
Setting @start_position differs from just passing over a shortened
string and setting RegexMatchFlags::NOTBOL in the case of a pattern
that begins with any kind of lookbehind assertion, such as “\b”.
Unless RegexCompileFlags::RAW is specified in the options, @string must be valid UTF-8.
A #GMatchInfo 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 #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().
⚠️ The following code is in C ⚠️
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);
}
}§string
the string to scan for matches
§start_position
starting index of the string to match, in bytes
§match_options
match options
§Returns
true is the string matched, false otherwise
§match_info
pointer to location where to store
the #GMatchInfo, or None if you do not need it
Sourcepub fn replace_literal(
&self,
string: impl IntoGStr,
start_position: i32,
replacement: impl IntoGStr,
match_options: RegexMatchFlags,
) -> Result<GString, Error>
pub fn replace_literal( &self, string: impl IntoGStr, start_position: i32, replacement: impl IntoGStr, match_options: RegexMatchFlags, ) -> Result<GString, Error>
Replaces all occurrences of the pattern in @self 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 RegexMatchFlags::NOTBOL in the
case of a pattern that begins with any kind of lookbehind
assertion, such as “\b”.
§string
the string to perform matches against
§start_position
starting index of the string to match, in bytes
§replacement
text to replace each match with
§match_options
options for the match
§Returns
a newly allocated string containing the replacements
Sourcepub fn split(
&self,
string: impl IntoGStr,
match_options: RegexMatchFlags,
) -> PtrSlice<GStringPtr>
pub fn split( &self, string: impl IntoGStr, match_options: RegexMatchFlags, ) -> PtrSlice<GStringPtr>
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 an 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”.
§string
the string to split with the pattern
§match_options
match time option flags
§Returns
a None-terminated gchar ** array. Free
it using g_strfreev()
Sourcepub fn split_full(
&self,
string: impl IntoGStr,
start_position: i32,
match_options: RegexMatchFlags,
max_tokens: i32,
) -> Result<PtrSlice<GStringPtr>, Error>
pub fn split_full( &self, string: impl IntoGStr, start_position: i32, match_options: RegexMatchFlags, max_tokens: i32, ) -> Result<PtrSlice<GStringPtr>, Error>
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 an 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 RegexMatchFlags::NOTBOL in the case of a pattern
that begins with any kind of lookbehind assertion, such as “\b”.
§string
the string to split with the pattern
§start_position
starting index of the string to match, in bytes
§match_options
match time option flags
§max_tokens
the maximum number of tokens to split @string into. If this is less than 1, the string is split completely
§Returns
a None-terminated gchar ** array. Free
it using g_strfreev()
Sourcepub fn split_simple(
pattern: impl IntoGStr,
string: impl IntoGStr,
compile_options: RegexCompileFlags,
match_options: RegexMatchFlags,
) -> PtrSlice<GStringPtr>
pub fn split_simple( pattern: impl IntoGStr, string: impl IntoGStr, compile_options: RegexCompileFlags, match_options: RegexMatchFlags, ) -> PtrSlice<GStringPtr>
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 an 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”.
§pattern
the regular expression
§string
the string to scan for matches
§compile_options
compile options for the regular expression, or 0
§match_options
match options, or 0
§Returns
a None-terminated array of strings. Free
it using g_strfreev()
Trait Implementations§
Source§impl HasParamSpec for Regex
impl HasParamSpec for Regex
Source§impl Ord for Regex
impl Ord for Regex
Source§impl PartialOrd for Regex
impl PartialOrd for Regex
Source§impl StaticType for Regex
impl StaticType for Regex
Source§fn static_type() -> Type
fn static_type() -> Type
Self.