Provided by: libstdc++-9-doc_9.5.0-6ubuntu2_all 
NAME
std::regex_traits< _Ch_type > - Describes aspects of a regular expression.
SYNOPSIS
#include <regex.h>
Public Types
typedef _RegexMask char_class_type
typedef _Ch_type char_type
typedef std::locale locale_type
typedef std::basic_string< char_type > string_type
Public Member Functions
regex_traits ()
Constructs a default traits object.
locale_type getloc () const
Gets a copy of the current locale in use by the regex_traits object.
locale_type imbue (locale_type __loc)
Imbues the regex_traits object with a copy of a new locale.
bool isctype (_Ch_type __c, char_class_type __f) const
Determines if c is a member of an identified class.
template<typename _Fwd_iter > char_class_type lookup_classname (_Fwd_iter __first, _Fwd_iter __last, bool
__icase=false) const
Maps one or more characters to a named character classification.
template<typename _Fwd_iter > string_type lookup_collatename (_Fwd_iter __first, _Fwd_iter __last) const
Gets a collation element by name.
template<typename _Fwd_iter > string_type transform (_Fwd_iter __first, _Fwd_iter __last) const
Gets a sort key for a character sequence.
template<typename _Fwd_iter > string_type transform_primary (_Fwd_iter __first, _Fwd_iter __last) const
Gets a sort key for a character sequence, independent of case.
char_type translate (char_type __c) const
Performs the identity translation.
char_type translate_nocase (char_type __c) const
Translates a character into a case-insensitive equivalent.
int value (_Ch_type __ch, int __radix) const
Converts a digit to an int.
Static Public Member Functions
static std::size_t length (const char_type *__p)
Gives the length of a C-style string starting at __p.
Protected Attributes
locale_type _M_locale
Detailed Description
template<typename _Ch_type>
class std::regex_traits< _Ch_type >"Describes aspects of a regular expression.
A regular expression traits class that satisfies the requirements of section [28.7].
The class regex is parameterized around a set of related types and functions used to complete the
definition of its semantics. This class satisfies the requirements of such a traits class.
Definition at line 80 of file regex.h.
Member Typedef Documentation
template<typename _Ch_type > typedef _RegexMask std::regex_traits< _Ch_type >::char_class_type
Definition at line 151 of file regex.h.
template<typename _Ch_type > typedef _Ch_type std::regex_traits< _Ch_type >::char_type
Definition at line 83 of file regex.h.
template<typename _Ch_type > typedef std::locale std::regex_traits< _Ch_type >::locale_type
Definition at line 85 of file regex.h.
template<typename _Ch_type > typedef std::basic_string<char_type> std::regex_traits< _Ch_type >::string_type
Definition at line 84 of file regex.h.
Constructor & Destructor Documentation
template<typename _Ch_type > std::regex_traits< _Ch_type >::regex_traits () [inline]
Constructs a default traits object.
Definition at line 157 of file regex.h.
Member Function Documentation
template<typename _Ch_type > locale_type std::regex_traits< _Ch_type >::getloc () const [inline]
Gets a copy of the current locale in use by the regex_traits object.
Definition at line 370 of file regex.h.
template<typename _Ch_type > locale_type std::regex_traits< _Ch_type >::imbue (locale_type __loc) [inline]
Imbues the regex_traits object with a copy of a new locale.
Parameters
__loc A locale.
Returns
a copy of the previous locale in use by the regex_traits object.
Note
Calling imbue with a different locale than the one currently in use invalidates all cached data held
by *this.
Definition at line 359 of file regex.h.
template<typename _Ch_type > bool std::regex_traits< _Ch_type >::isctype (_Ch_type __c, char_class_type __f)
const
Determines if c is a member of an identified class.
Parameters
__c a character.
__f a class type (as returned from lookup_classname).
Returns
true if the character __c is a member of the classification represented by __f, false otherwise.
Exceptions
std::bad_cast if the current locale does not have a ctype facet.
Definition at line 326 of file regex.tcc.
template<typename _Ch_type > static std::size_t std::regex_traits< _Ch_type >::length (const char_type * __p)
[inline], [static]
Gives the length of a C-style string starting at __p.
Parameters
__p a pointer to the start of a character sequence.
Returns
the number of characters between *__p and the first default-initialized value of type char_type. In
other words, uses the C-string algorithm for determining the length of a sequence of characters.
Definition at line 170 of file regex.h.
template<typename _Ch_type > template<typename _Fwd_iter > regex_traits< _Ch_type >::char_class_type
std::regex_traits< _Ch_type >::lookup_classname (_Fwd_iter __first, _Fwd_iter __last, bool __icase =
false) const
Maps one or more characters to a named character classification.
Parameters
__first beginning of the character sequence.
__last one-past-the-end of the character sequence.
__icase ignores the case of the classification name.
Returns
an unspecified value that represents the character classification named by the character sequence
designated by the iterator range [__first, __last). If icase is true, the returned mask identifies
the classification regardless of the case of the characters to be matched (for example, [[:lower:]]
is the same as [[:alpha:]]), otherwise a case-dependent classification is returned. The value
returned shall be independent of the case of the characters in the character sequence. If the name is
not recognized then returns a value that compares equal to 0.
At least the following names (or their wide-character equivalent) are supported.
• d
• w
• s
• alnum
• alpha
• blank
• cntrl
• digit
• graph
• lower
• print
• punct
• space
• upper
• xdigit
Definition at line 282 of file regex.tcc.
template<typename _Ch_type > template<typename _Fwd_iter > regex_traits< _Ch_type >::string_type
std::regex_traits< _Ch_type >::lookup_collatename (_Fwd_iter __first, _Fwd_iter __last) const
Gets a collation element by name.
Parameters
__first beginning of the collation element name.
__last one-past-the-end of the collation element name.
Returns
a sequence of one or more characters that represents the collating element consisting of the
character sequence designated by the iterator range [__first, __last). Returns an empty string if the
character sequence is not a valid collating element.
Definition at line 126 of file regex.tcc.
template<typename _Ch_type > template<typename _Fwd_iter > string_type std::regex_traits< _Ch_type
>::transform (_Fwd_iter __first, _Fwd_iter __last) const [inline]
Gets a sort key for a character sequence.
Parameters
__first beginning of the character sequence.
__last one-past-the-end of the character sequence.
Returns a sort key for the character sequence designated by the iterator range [F1, F2) such that if the
character sequence [G1, G2) sorts before the character sequence [H1, H2) then v.transform(G1, G2) <
v.transform(H1, H2).
What this really does is provide a more efficient way to compare a string to multiple other strings in
locales with fancy collation rules and equivalence classes.
Returns
a locale-specific sort key equivalent to the input range.
Exceptions
std::bad_cast if the current locale does not have a collate facet.
Definition at line 223 of file regex.h.
Referenced by std::regex_traits< _Ch_type >::transform_primary().
template<typename _Ch_type > template<typename _Fwd_iter > string_type std::regex_traits< _Ch_type
>::transform_primary (_Fwd_iter __first, _Fwd_iter __last) const [inline]
Gets a sort key for a character sequence, independent of case.
Parameters
__first beginning of the character sequence.
__last one-past-the-end of the character sequence.
Effects: if typeid(use_facet<collate<_Ch_type> >) == typeid(collate_byname<_Ch_type>) and the form of the
sort key returned by collate_byname<_Ch_type>::transform(__first, __last) is known and can be converted
into a primary sort key then returns that key, otherwise returns an empty string.
Todo
Implement this function correctly.
Definition at line 247 of file regex.h.
References std::regex_traits< _Ch_type >::transform().
template<typename _Ch_type > char_type std::regex_traits< _Ch_type >::translate (char_type __c) const
[inline]
Performs the identity translation.
Parameters
__c A character to the locale-specific character set.
Returns
__c.
Definition at line 181 of file regex.h.
template<typename _Ch_type > char_type std::regex_traits< _Ch_type >::translate_nocase (char_type __c) const
[inline]
Translates a character into a case-insensitive equivalent.
Parameters
__c A character to the locale-specific character set.
Returns
the locale-specific lower-case equivalent of __c.
Exceptions
std::bad_cast if the imbued locale does not support the ctype facet.
Definition at line 194 of file regex.h.
template<typename _Ch_type > int std::regex_traits< _Ch_type >::value (_Ch_type __ch, int __radix) const
Converts a digit to an int.
Parameters
__ch a character representing a digit.
__radix the radix if the numeric conversion (limited to 8, 10, or 16).
Returns
the value represented by the digit __ch in base radix if the character __ch is a valid digit in base
radix; otherwise returns -1.
Definition at line 340 of file regex.tcc.
Member Data Documentation
template<typename _Ch_type > locale_type std::regex_traits< _Ch_type >::_M_locale [protected]
Definition at line 374 of file regex.h.
Author
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