Copyright | Will Thompson and Iñaki García Etxebarria |
---|---|
License | LGPL-2.1 |
Maintainer | Iñaki García Etxebarria |
Safe Haskell | None |
Language | Haskell2010 |
GI.GLib.Structs.Regex
Contents
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.
{ .c } code
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:
- [flags
gLib
.RegexCompileFlags]—These flags control how GLib compiles the regex. There are options for case sensitivity, multiline, ignoring whitespace, etc. - [flags
gLib
.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.
{ .c } code
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
.
{ .c } code
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 regexMatchFull
(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 [flagsgLib
.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 [flagsgLib
.RegexMatchFlags.NEWLINE_CR],
[flagsgLib
.RegexMatchFlags.NEWLINE_LF], and
[flagsgLib
.RegexMatchFlags.NEWLINE_CRLF] compile options, and
with [flagsgLib
.RegexMatchFlags.NEWLINE_ANY],
[flagsgLib
.RegexMatchFlags.NEWLINE_CR],
[flagsgLib
.RegexMatchFlags.NEWLINE_LF] and
[flagsgLib
.RegexMatchFlags.NEWLINE_CRLF] match options.
These settings are also relevant when compiling a pattern if
[flagsgLib
.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.
Since: 2.14
Synopsis
- newtype Regex = Regex (ManagedPtr Regex)
- regexCheckReplacement :: (HasCallStack, MonadIO m) => Text -> m Bool
- regexErrorQuark :: (HasCallStack, MonadIO m) => m Word32
- regexEscapeNul :: (HasCallStack, MonadIO m) => Text -> Int32 -> m Text
- regexEscapeString :: (HasCallStack, MonadIO m) => Text -> Int32 -> m Text
- regexGetCaptureCount :: (HasCallStack, MonadIO m) => Regex -> m Int32
- regexGetCompileFlags :: (HasCallStack, MonadIO m) => Regex -> m [RegexCompileFlags]
- regexGetHasCrOrLf :: (HasCallStack, MonadIO m) => Regex -> m Bool
- regexGetMatchFlags :: (HasCallStack, MonadIO m) => Regex -> m [RegexMatchFlags]
- regexGetMaxBackref :: (HasCallStack, MonadIO m) => Regex -> m Int32
- regexGetMaxLookbehind :: (HasCallStack, MonadIO m) => Regex -> m Int32
- regexGetPattern :: (HasCallStack, MonadIO m) => Regex -> m Text
- regexGetStringNumber :: (HasCallStack, MonadIO m) => Regex -> Text -> m Int32
- regexMatch :: (HasCallStack, MonadIO m) => Regex -> Text -> [RegexMatchFlags] -> m (Bool, MatchInfo)
- regexMatchAll :: (HasCallStack, MonadIO m) => Regex -> Text -> [RegexMatchFlags] -> m (Bool, MatchInfo)
- regexMatchAllFull :: (HasCallStack, MonadIO m) => Regex -> [Text] -> Int32 -> [RegexMatchFlags] -> m MatchInfo
- regexMatchFull :: (HasCallStack, MonadIO m) => Regex -> [Text] -> Int32 -> [RegexMatchFlags] -> m MatchInfo
- regexMatchSimple :: (HasCallStack, MonadIO m) => Text -> Text -> [RegexCompileFlags] -> [RegexMatchFlags] -> m Bool
- regexNew :: (HasCallStack, MonadIO m) => Text -> [RegexCompileFlags] -> [RegexMatchFlags] -> m (Maybe Regex)
- regexRef :: (HasCallStack, MonadIO m) => Regex -> m Regex
- regexReplace :: (HasCallStack, MonadIO m) => Regex -> [Text] -> Int32 -> Text -> [RegexMatchFlags] -> m Text
- regexReplaceEval :: (HasCallStack, MonadIO m) => Regex -> [Text] -> Int32 -> [RegexMatchFlags] -> RegexEvalCallback -> m Text
- regexReplaceLiteral :: (HasCallStack, MonadIO m) => Regex -> [Text] -> Int32 -> Text -> [RegexMatchFlags] -> m Text
- regexSplit :: (HasCallStack, MonadIO m) => Regex -> Text -> [RegexMatchFlags] -> m [Text]
- regexSplitFull :: (HasCallStack, MonadIO m) => Regex -> [Text] -> Int32 -> [RegexMatchFlags] -> Int32 -> m [Text]
- regexSplitSimple :: (HasCallStack, MonadIO m) => Text -> Text -> [RegexCompileFlags] -> [RegexMatchFlags] -> m [Text]
- regexUnref :: (HasCallStack, MonadIO m) => Regex -> m ()
Exported types
Memory-managed wrapper type.
Constructors
Regex (ManagedPtr Regex) |
Instances
Eq Regex Source # | |
GBoxed Regex Source # | |
Defined in GI.GLib.Structs.Regex | |
ManagedPtrNewtype Regex Source # | |
Defined in GI.GLib.Structs.Regex Methods toManagedPtr :: Regex -> ManagedPtr Regex # | |
TypedObject Regex Source # | |
Defined in GI.GLib.Structs.Regex | |
HasParentTypes Regex Source # | |
Defined in GI.GLib.Structs.Regex | |
IsGValue (Maybe Regex) Source # | Convert |
Defined in GI.GLib.Structs.Regex Methods gvalueGType_ :: IO GType # gvalueSet_ :: Ptr GValue -> Maybe Regex -> IO () # gvalueGet_ :: Ptr GValue -> IO (Maybe Regex) # | |
type ParentTypes Regex Source # | |
Defined in GI.GLib.Structs.Regex type ParentTypes Regex = '[] :: [Type] |
Methods
Click to display all available methods, including inherited ones
Methods
match, matchAll, matchAllFull, matchFull, ref, replace, replaceEval, replaceLiteral, split, splitFull, unref.
Getters
getCaptureCount, getCompileFlags, getHasCrOrLf, getMatchFlags, getMaxBackref, getMaxLookbehind, getPattern, getStringNumber.
Setters
None.
checkReplacement
regexCheckReplacement Source #
Arguments
:: (HasCallStack, MonadIO m) | |
=> Text |
|
-> m Bool | (Can throw |
Checks whether replacement
is a valid replacement string
(see regexReplace
), i.e. that all escape sequences in
it are valid.
If hasReferences
is not Nothing
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 MatchInfo
object.
Since: 2.14
errorQuark
regexErrorQuark :: (HasCallStack, MonadIO m) => m Word32 Source #
No description available in the introspection data.
escapeNul
Arguments
:: (HasCallStack, MonadIO m) | |
=> Text |
|
-> Int32 |
|
-> m Text | Returns: a newly-allocated escaped 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
Arguments
:: (HasCallStack, MonadIO m) | |
=> Text |
|
-> Int32 |
|
-> m Text | Returns: a newly-allocated escaped 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
getCaptureCount
Arguments
:: (HasCallStack, MonadIO m) | |
=> Regex |
|
-> m Int32 | Returns: the number of capturing subpatterns |
Returns the number of capturing subpatterns in the pattern.
Since: 2.14
getCompileFlags
Arguments
:: (HasCallStack, MonadIO m) | |
=> Regex |
|
-> m [RegexCompileFlags] | Returns: flags from |
Returns the compile options that regex
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.
Since: 2.26
getHasCrOrLf
Arguments
:: (HasCallStack, MonadIO m) | |
=> Regex |
|
-> m Bool | Returns: |
Checks whether the pattern contains explicit CR or LF references.
Since: 2.34
getMatchFlags
Arguments
:: (HasCallStack, MonadIO m) | |
=> Regex |
|
-> m [RegexMatchFlags] | Returns: flags from |
Returns the match options that regex
was created with.
Since: 2.26
getMaxBackref
Arguments
:: (HasCallStack, MonadIO m) | |
=> Regex |
|
-> m Int32 | Returns: the number of the highest back reference |
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
regexGetMaxLookbehind Source #
Arguments
:: (HasCallStack, MonadIO m) | |
=> Regex |
|
-> m Int32 | Returns: the number of characters in the longest lookbehind assertion. |
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
Arguments
:: (HasCallStack, MonadIO m) | |
=> Regex |
|
-> m Text | Returns: the pattern of |
Gets the pattern string associated with regex
, i.e. a copy of
the string passed to regexNew
.
Since: 2.14
getStringNumber
Arguments
:: (HasCallStack, MonadIO m) | |
=> Regex |
|
-> Text |
|
-> m Int32 | Returns: The number of the subexpression or -1 if |
Retrieves the number of the subexpression named name
.
Since: 2.14
match
Arguments
:: (HasCallStack, MonadIO m) | |
=> Regex | |
-> Text |
|
-> [RegexMatchFlags] |
|
-> m (Bool, MatchInfo) |
Scans for a match in string
for the pattern in regex
.
The matchOptions
are combined with the match options specified
when the regex
structure was created, letting you have more
flexibility in reusing Regex
structures.
Unless RegexCompileFlagsRaw
is specified in the options, string
must be valid UTF-8.
A MatchInfo
structure, used to get information on the match,
is stored in matchInfo
if not Nothing
. Note that if matchInfo
is not Nothing
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 matchInfoNext
.
C code
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 MatchInfo
internally. If
you use any MatchInfo
method (except matchInfoFree
) after
freeing or modifying string
then the behaviour is undefined.
Since: 2.14
matchAll
Arguments
:: (HasCallStack, MonadIO m) | |
=> Regex | |
-> Text |
|
-> [RegexMatchFlags] |
|
-> m (Bool, 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 regexMatchAllFull
.
A MatchInfo
structure, used to get information on the match, is
stored in matchInfo
if not Nothing
. Note that if matchInfo
is
not Nothing
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 MatchInfo
internally. If
you use any MatchInfo
method (except matchInfoFree
) after
freeing or modifying string
then the behaviour is undefined.
Since: 2.14
matchAllFull
Arguments
:: (HasCallStack, MonadIO m) | |
=> Regex | |
-> [Text] |
|
-> Int32 |
|
-> [RegexMatchFlags] |
|
-> m MatchInfo | (Can throw |
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
matchInfoGetMatchCount
. To obtain the matched strings and
their position you can use, respectively, matchInfoFetch
and
matchInfoFetchPos
. 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 startPosition
differs from just passing over a shortened
string and setting RegexMatchFlagsNotbol
in the case of a pattern
that begins with any kind of lookbehind assertion, such as "\b".
Unless RegexCompileFlagsRaw
is specified in the options, string
must be valid UTF-8.
A MatchInfo
structure, used to get information on the match, is
stored in matchInfo
if not Nothing
. Note that if matchInfo
is
not Nothing
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 MatchInfo
internally. If
you use any MatchInfo
method (except matchInfoFree
) after
freeing or modifying string
then the behaviour is undefined.
Since: 2.14
matchFull
Arguments
:: (HasCallStack, MonadIO m) | |
=> Regex | |
-> [Text] |
|
-> Int32 |
|
-> [RegexMatchFlags] |
|
-> m MatchInfo | (Can throw |
Scans for a match in string
for the pattern in regex
.
The matchOptions
are combined with the match options specified
when the regex
structure was created, letting you have more
flexibility in reusing Regex
structures.
Setting startPosition
differs from just passing over a shortened
string and setting RegexMatchFlagsNotbol
in the case of a pattern
that begins with any kind of lookbehind assertion, such as "\b".
Unless RegexCompileFlagsRaw
is specified in the options, string
must be valid UTF-8.
A MatchInfo
structure, used to get information on the match, is
stored in matchInfo
if not Nothing
. Note that if matchInfo
is
not Nothing
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 MatchInfo
internally. If
you use any MatchInfo
method (except matchInfoFree
) 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 matchInfoNext
.
C code
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); } }
Since: 2.14
matchSimple
Arguments
:: (HasCallStack, MonadIO m) | |
=> Text |
|
-> Text |
|
-> [RegexCompileFlags] |
|
-> [RegexMatchFlags] |
|
-> m Bool |
Scans for a match in string
for pattern
.
This function is equivalent to regexMatch
but it does not
require to compile the pattern with regexNew
, 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
regexNew
and then use regexMatch
.
Since: 2.14
new
Arguments
:: (HasCallStack, MonadIO m) | |
=> Text |
|
-> [RegexCompileFlags] |
|
-> [RegexMatchFlags] |
|
-> m (Maybe Regex) | Returns: a |
Compiles the regular expression to an internal form, and does
the initial setup of the Regex
structure.
Since: 2.14
ref
Increases reference count of regex
by 1.
Since: 2.14
replace
Arguments
:: (HasCallStack, MonadIO m) | |
=> Regex |
|
-> [Text] |
|
-> Int32 |
|
-> Text |
|
-> [RegexMatchFlags] |
|
-> m Text | Returns: a newly allocated string containing the replacements (Can throw |
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 \\\\
.
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 regexReplaceLiteral
.
The replacement
string must be UTF-8 encoded even if RegexCompileFlagsRaw
was
passed to regexNew
. If you want to use not UTF-8 encoded strings
you can use regexReplaceLiteral
.
Setting startPosition
differs from just passing over a shortened
string and setting RegexMatchFlagsNotbol
in the case of a pattern that
begins with any kind of lookbehind assertion, such as "\b".
Since: 2.14
replaceEval
Arguments
:: (HasCallStack, MonadIO m) | |
=> Regex | |
-> [Text] |
|
-> Int32 |
|
-> [RegexMatchFlags] |
|
-> RegexEvalCallback |
|
-> m Text | Returns: a newly allocated string containing the replacements (Can throw |
Replaces occurrences of the pattern in regex with the output of
eval
for that occurrence.
Setting startPosition
differs from just passing over a shortened
string and setting RegexMatchFlagsNotbol
in the case of a pattern
that begins with any kind of lookbehind assertion, such as "\b".
The following example uses regexReplaceEval
to replace multiple
strings at once:
C code
static gboolean eval_cb (const GMatchInfo *info, GString *res, gpointer data) { gchar *match; gchar *r; match = g_match_info_fetch (info, 0); r = g_hash_table_lookup ((GHashTable *)data, match); g_string_append (res, r); g_free (match); return FALSE; } ... GRegex *reg; GHashTable *h; gchar *res; h = g_hash_table_new (g_str_hash, g_str_equal); g_hash_table_insert (h, "1", "ONE"); g_hash_table_insert (h, "2", "TWO"); g_hash_table_insert (h, "3", "THREE"); g_hash_table_insert (h, "4", "FOUR"); reg = g_regex_new ("1|2|3|4", G_REGEX_DEFAULT, G_REGEX_MATCH_DEFAULT, NULL); res = g_regex_replace_eval (reg, text, -1, 0, 0, eval_cb, h, NULL); g_hash_table_destroy (h); ...
Since: 2.14
replaceLiteral
Arguments
:: (HasCallStack, MonadIO m) | |
=> Regex |
|
-> [Text] |
|
-> Int32 |
|
-> Text |
|
-> [RegexMatchFlags] |
|
-> m Text | Returns: a newly allocated string containing the replacements (Can throw |
Replaces all occurrences of the pattern in regex
with the
replacement text. replacement
is replaced literally, to
include backreferences use regexReplace
.
Setting startPosition
differs from just passing over a
shortened string and setting RegexMatchFlagsNotbol
in the
case of a pattern that begins with any kind of lookbehind
assertion, such as "\b".
Since: 2.14
split
Arguments
:: (HasCallStack, MonadIO m) | |
=> Regex |
|
-> Text |
|
-> [RegexMatchFlags] |
|
-> m [Text] | Returns: a |
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".
Since: 2.14
splitFull
Arguments
:: (HasCallStack, MonadIO m) | |
=> Regex |
|
-> [Text] |
|
-> Int32 |
|
-> [RegexMatchFlags] |
|
-> Int32 |
|
-> m [Text] | Returns: a |
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 startPosition
differs from just passing over a shortened
string and setting RegexMatchFlagsNotbol
in the case of a pattern
that begins with any kind of lookbehind assertion, such as "\b".
Since: 2.14
splitSimple
Arguments
:: (HasCallStack, MonadIO m) | |
=> Text |
|
-> Text |
|
-> [RegexCompileFlags] |
|
-> [RegexMatchFlags] |
|
-> m [Text] | Returns: a |
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 regexSplit
but it does
not require to compile the pattern with regexNew
, 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
regexNew
and then use regexSplit
.
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".
Since: 2.14
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