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## Struct template c_regex_traits

boost::xpressive::c_regex_traits — Encapsaulates the standard C locale functions for use by the basic_regex<> class template.

## Synopsis

    template<typename Char>
    struct c_regex_traits {
      // types
      typedef Char                           char_type;
      typedef std::basic_string< char_type > string_type;
      typedef unspecified                    locale_type;
      typedef unspecified                    char_class_type;
      typedef regex_traits_version_1_tag     version_tag;
      typedef unspecified                    base_type;

      // construct/copy/destruct
      c_regex_traits(locale_type const & = locale_type());

      // public member functions
      bool operator==(c_regex_traits< char_type > const &) const;
      bool operator!=(c_regex_traits< char_type > const &) const;
      locale_type imbue(locale_type) ;

      // public static functions
      static unsigned char hash(char_type) ;
      static char_type translate(char_type) ;
      static char_type translate_nocase(char_type) ;
      static bool in_range(char_type, char_type, char_type) ;
      static bool in_range_nocase(char_type, char_type, char_type) ;
      template<typename FwdIter> static string_type transform(FwdIter, FwdIter) ;
      template<typename FwdIter>
        static string_type transform_primary(FwdIter, FwdIter) ;
      template<typename FwdIter>
        static string_type lookup_collatename(FwdIter, FwdIter) ;
      template<typename FwdIter>
        static char_class_type lookup_classname(FwdIter, FwdIter, bool) ;
      static bool isctype(char_type, char_class_type) ;
      static int value(char_type, int) ;
      static locale_type getloc() ;
    };

## Description

### `c_regex_traits` construct/copy/destruct

1.     c_regex_traits(locale_type const & loc = locale_type());

   Initialize a c_regex_traits object to use the global C locale.

### `c_regex_traits` public member functions

1.     bool operator==(c_regex_traits< char_type > const & that) const;

   Checks two c_regex_traits objects for equality

   Returns: | true.

2.     bool operator!=(c_regex_traits< char_type > const & that) const;

   Checks two c_regex_traits objects for inequality

   Returns: | false.

3.     locale_type imbue(locale_type loc) ;

   No-op

### `c_regex_traits` public static functions

1.     static unsigned char hash(char_type ch) ;

   Returns a hash value for a Char in the range [0, UCHAR_MAX]

   Parameters: |

   `ch` | The source character.

   Returns: | a value between 0 and UCHAR_MAX, inclusive.

2.     static char_type translate(char_type ch) ;

   No-op

   Parameters: |

   `ch` | The source character.

   Returns: | ch

3.     static char_type translate_nocase(char_type ch) ;

   Converts a character to lower-case using the current global C locale.

   Parameters: |

   `ch` | The source character.

   Returns: | std::tolower(ch) if Char is char, std::towlower(ch) if Char is wchar_t.

4.     static bool in_range(char_type first, char_type last, char_type ch) ;

   Checks to see if a character is within a character range.

   Parameters: |

   `ch` | The source character.
   `first` | The bottom of the range, inclusive.
   `last` | The top of the range, inclusive.

   Returns: | first <= ch && ch <= last.

5.     static bool in_range_nocase(char_type first, char_type last, char_type ch) ;

   Checks to see if a character is within a character range, irregardless of case.

   Parameters: |

   `ch` | The source character.
   `first` | The bottom of the range, inclusive.
   `last` | The top of the range, inclusive.

   Returns: | in_range(first, last, ch) || in_range(first, last, tolower(ch)) || in_range(first, last, toupper(ch))
   Notes: | The default implementation doesn't do proper Unicode case folding, but this is the best we can do with the standard C locale functions.

6.     template<typename FwdIter>
         static string_type transform(FwdIter begin, FwdIter end) ;

   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).

   Notes: | Not used in xpressive 1.0

7.     template<typename FwdIter>
         static string_type transform_primary(FwdIter begin, FwdIter end) ;

   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) when character case is not considered then v.transform_primary(G1, G2) < v.transform_primary(H1, H2).

   Notes: | Not used in xpressive 1.0

8.     template<typename FwdIter>
         static string_type lookup_collatename(FwdIter begin, FwdIter end) ;

   Returns a sequence of characters that represents the collating element consisting of the character sequence designated by the iterator range [F1, F2). Returns an empty string if the character sequence is not a valid collating element.

   Notes: | Not used in xpressive 1.0

9.     template<typename FwdIter>
         static char_class_type
         lookup_classname(FwdIter begin, FwdIter end, bool icase) ;

   For the character class name represented by the specified character sequence, return the corresponding bitmask representation.

   Parameters: |

   `begin` | A forward iterator to the start of the character sequence representing the name of the character class.
   `end` | The end of the character sequence.
   `icase` | Specifies whether the returned bitmask should represent the case-insensitive version of the character class.

   Returns: | A bitmask representing the character class.

10.     static bool isctype(char_type ch, char_class_type mask) ;

    Tests a character against a character class bitmask.

    Parameters: |

    `ch` | The character to test.
    `mask` | The character class bitmask against which to test.

    Requires: | mask is a bitmask returned by lookup_classname, or is several such masks bit-or'ed together.
    Returns: | true if the character is a member of any of the specified character classes, false otherwise.

11.     static int value(char_type ch, int radix) ;

    Convert a digit character into the integer it represents.

    Parameters: |

    `ch` | The digit character.
    `radix` | The radix to use for the conversion.

    Requires: | radix is one of 8, 10, or 16.
    Returns: | -1 if ch is not a digit character, the integer value of the character otherwise. If char_type is char, std::strtol is used for the conversion. If char_type is wchar_t, std::wcstol is used.

12.     static locale_type getloc() ;

    No-op

| Copyright © 2003, 2004 Eric Niebler