std::regex_traits< _Ch_type >(3cxx) std::regex_traits< _Ch_type >(3cxx)
NAME
std::regex_traits< _Ch_type > - Describes aspects of a regular
expression.
SYNOPSIS
#include <regex>
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.
Since
C++11
Constructor & Destructor Documentation
template<typename _Ch_type > std::regex_traits< _Ch_type >::regex_traits ()
[inline]
Constructs a default traits object.
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.
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.
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.
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.
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
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.
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.
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.
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.
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.
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.
References std::hex(), and std::oct().
Author
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