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.

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 > 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 > 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.

       References std::basic_string< _CharT, _Traits, _Alloc >::data(), and std::basic_string<
       _CharT, _Traits, _Alloc >::size().

       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::vector< _Tp, _Alloc >::data(), std::vector< _Tp, _Alloc >::size(), and
       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.

Author

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