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  1. // Locale support -*- C++ -*-
  2.  
  3. // Copyright (C) 1997-2013 Free Software Foundation, Inc.
  4. //
  5. // This file is part of the GNU ISO C++ Library.  This library is free
  6. // software; you can redistribute it and/or modify it under the
  7. // terms of the GNU General Public License as published by the
  8. // Free Software Foundation; either version 3, or (at your option)
  9. // any later version.
  10.  
  11. // This library is distributed in the hope that it will be useful,
  12. // but WITHOUT ANY WARRANTY; without even the implied warranty of
  13. // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14. // GNU General Public License for more details.
  15.  
  16. // Under Section 7 of GPL version 3, you are granted additional
  17. // permissions described in the GCC Runtime Library Exception, version
  18. // 3.1, as published by the Free Software Foundation.
  19.  
  20. // You should have received a copy of the GNU General Public License and
  21. // a copy of the GCC Runtime Library Exception along with this program;
  22. // see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
  23. // <http://www.gnu.org/licenses/>.
  24.  
  25. /** @file bits/locale_classes.h
  26.  *  This is an internal header file, included by other library headers.
  27.  *  Do not attempt to use it directly. @headername{locale}
  28.  */
  29.  
  30. //
  31. // ISO C++ 14882: 22.1  Locales
  32. //
  33.  
  34. #ifndef _LOCALE_CLASSES_H
  35. #define _LOCALE_CLASSES_H 1
  36.  
  37. #pragma GCC system_header
  38.  
  39. #include <bits/localefwd.h>
  40. #include <string>
  41. #include <ext/atomicity.h>
  42.  
  43. namespace std _GLIBCXX_VISIBILITY(default)
  44. {
  45. _GLIBCXX_BEGIN_NAMESPACE_VERSION
  46.  
  47.   // 22.1.1 Class locale
  48.   /**
  49.    *  @brief  Container class for localization functionality.
  50.    *  @ingroup locales
  51.    *
  52.    *  The locale class is first a class wrapper for C library locales.  It is
  53.    *  also an extensible container for user-defined localization.  A locale is
  54.    *  a collection of facets that implement various localization features such
  55.    *  as money, time, and number printing.
  56.    *
  57.    *  Constructing C++ locales does not change the C library locale.
  58.    *
  59.    *  This library supports efficient construction and copying of locales
  60.    *  through a reference counting implementation of the locale class.
  61.   */
  62.   class locale
  63.   {
  64.   public:
  65.     // Types:
  66.     /// Definition of locale::category.
  67.     typedef int category;
  68.  
  69.     // Forward decls and friends:
  70.     class facet;
  71.     class id;
  72.     class _Impl;
  73.  
  74.     friend class facet;
  75.     friend class _Impl;
  76.  
  77.     template<typename _Facet>
  78.       friend bool
  79.       has_facet(const locale&) throw();
  80.  
  81.     template<typename _Facet>
  82.       friend const _Facet&
  83.       use_facet(const locale&);
  84.  
  85.     template<typename _Cache>
  86.       friend struct __use_cache;
  87.  
  88.     //@{
  89.     /**
  90.      *  @brief  Category values.
  91.      *
  92.      *  The standard category values are none, ctype, numeric, collate, time,
  93.      *  monetary, and messages.  They form a bitmask that supports union and
  94.      *  intersection.  The category all is the union of these values.
  95.      *
  96.      *  NB: Order must match _S_facet_categories definition in locale.cc
  97.     */
  98.     static const category none          = 0;
  99.     static const category ctype         = 1L << 0;
  100.     static const category numeric       = 1L << 1;
  101.     static const category collate       = 1L << 2;
  102.     static const category time          = 1L << 3;
  103.     static const category monetary      = 1L << 4;
  104.     static const category messages      = 1L << 5;
  105.     static const category all           = (ctype | numeric | collate |
  106.                                            time  | monetary | messages);
  107.     //@}
  108.  
  109.     // Construct/copy/destroy:
  110.  
  111.     /**
  112.      *  @brief  Default constructor.
  113.      *
  114.      *  Constructs a copy of the global locale.  If no locale has been
  115.      *  explicitly set, this is the C locale.
  116.     */
  117.     locale() throw();
  118.  
  119.     /**
  120.      *  @brief  Copy constructor.
  121.      *
  122.      *  Constructs a copy of @a other.
  123.      *
  124.      *  @param  __other  The locale to copy.
  125.     */
  126.     locale(const locale& __other) throw();
  127.  
  128.     /**
  129.      *  @brief  Named locale constructor.
  130.      *
  131.      *  Constructs a copy of the named C library locale.
  132.      *
  133.      *  @param  __s  Name of the locale to construct.
  134.      *  @throw  std::runtime_error if __s is null or an undefined locale.
  135.     */
  136.     explicit
  137.     locale(const char* __s);
  138.  
  139.     /**
  140.      *  @brief  Construct locale with facets from another locale.
  141.      *
  142.      *  Constructs a copy of the locale @a base.  The facets specified by @a
  143.      *  cat are replaced with those from the locale named by @a s.  If base is
  144.      *  named, this locale instance will also be named.
  145.      *
  146.      *  @param  __base  The locale to copy.
  147.      *  @param  __s  Name of the locale to use facets from.
  148.      *  @param  __cat  Set of categories defining the facets to use from __s.
  149.      *  @throw  std::runtime_error if __s is null or an undefined locale.
  150.     */
  151.     locale(const locale& __base, const char* __s, category __cat);
  152.  
  153.     /**
  154.      *  @brief  Construct locale with facets from another locale.
  155.      *
  156.      *  Constructs a copy of the locale @a base.  The facets specified by @a
  157.      *  cat are replaced with those from the locale @a add.  If @a base and @a
  158.      *  add are named, this locale instance will also be named.
  159.      *
  160.      *  @param  __base  The locale to copy.
  161.      *  @param  __add  The locale to use facets from.
  162.      *  @param  __cat  Set of categories defining the facets to use from add.
  163.     */
  164.     locale(const locale& __base, const locale& __add, category __cat);
  165.  
  166.     /**
  167.      *  @brief  Construct locale with another facet.
  168.      *
  169.      *  Constructs a copy of the locale @a __other.  The facet @a __f
  170.      *  is added to @a __other, replacing an existing facet of type
  171.      *  Facet if there is one.  If @a __f is null, this locale is a
  172.      *  copy of @a __other.
  173.      *
  174.      *  @param  __other  The locale to copy.
  175.      *  @param  __f  The facet to add in.
  176.     */
  177.     template<typename _Facet>
  178.       locale(const locale& __other, _Facet* __f);
  179.  
  180.     /// Locale destructor.
  181.     ~locale() throw();
  182.  
  183.     /**
  184.      *  @brief  Assignment operator.
  185.      *
  186.      *  Set this locale to be a copy of @a other.
  187.      *
  188.      *  @param  __other  The locale to copy.
  189.      *  @return  A reference to this locale.
  190.     */
  191.     const locale&
  192.     operator=(const locale& __other) throw();
  193.  
  194.     /**
  195.      *  @brief  Construct locale with another facet.
  196.      *
  197.      *  Constructs and returns a new copy of this locale.  Adds or replaces an
  198.      *  existing facet of type Facet from the locale @a other into the new
  199.      *  locale.
  200.      *
  201.      *  @tparam  _Facet  The facet type to copy from other
  202.      *  @param  __other  The locale to copy from.
  203.      *  @return  Newly constructed locale.
  204.      *  @throw  std::runtime_error if __other has no facet of type _Facet.
  205.     */
  206.     template<typename _Facet>
  207.       locale
  208.       combine(const locale& __other) const;
  209.  
  210.     // Locale operations:
  211.     /**
  212.      *  @brief  Return locale name.
  213.      *  @return  Locale name or "*" if unnamed.
  214.     */
  215.     string
  216.     name() const;
  217.  
  218.     /**
  219.      *  @brief  Locale equality.
  220.      *
  221.      *  @param  __other  The locale to compare against.
  222.      *  @return  True if other and this refer to the same locale instance, are
  223.      *           copies, or have the same name.  False otherwise.
  224.     */
  225.     bool
  226.     operator==(const locale& __other) const throw();
  227.  
  228.     /**
  229.      *  @brief  Locale inequality.
  230.      *
  231.      *  @param  __other  The locale to compare against.
  232.      *  @return  ! (*this == __other)
  233.     */
  234.     bool
  235.     operator!=(const locale& __other) const throw()
  236.     { return !(this->operator==(__other)); }
  237.  
  238.     /**
  239.      *  @brief  Compare two strings according to collate.
  240.      *
  241.      *  Template operator to compare two strings using the compare function of
  242.      *  the collate facet in this locale.  One use is to provide the locale to
  243.      *  the sort function.  For example, a vector v of strings could be sorted
  244.      *  according to locale loc by doing:
  245.      *  @code
  246.      *  std::sort(v.begin(), v.end(), loc);
  247.      *  @endcode
  248.      *
  249.      *  @param  __s1  First string to compare.
  250.      *  @param  __s2  Second string to compare.
  251.      *  @return  True if collate<_Char> facet compares __s1 < __s2, else false.
  252.     */
  253.     template<typename _Char, typename _Traits, typename _Alloc>
  254.       bool
  255.       operator()(const basic_string<_Char, _Traits, _Alloc>& __s1,
  256.                  const basic_string<_Char, _Traits, _Alloc>& __s2) const;
  257.  
  258.     // Global locale objects:
  259.     /**
  260.      *  @brief  Set global locale
  261.      *
  262.      *  This function sets the global locale to the argument and returns a
  263.      *  copy of the previous global locale.  If the argument has a name, it
  264.      *  will also call std::setlocale(LC_ALL, loc.name()).
  265.      *
  266.      *  @param  __loc  The new locale to make global.
  267.      *  @return  Copy of the old global locale.
  268.     */
  269.     static locale
  270.     global(const locale& __loc);
  271.  
  272.     /**
  273.      *  @brief  Return reference to the C locale.
  274.     */
  275.     static const locale&
  276.     classic();
  277.  
  278.   private:
  279.     // The (shared) implementation
  280.     _Impl*              _M_impl;
  281.  
  282.     // The "C" reference locale
  283.     static _Impl*       _S_classic;
  284.  
  285.     // Current global locale
  286.     static _Impl*       _S_global;
  287.  
  288.     // Names of underlying locale categories.
  289.     // NB: locale::global() has to know how to modify all the
  290.     // underlying categories, not just the ones required by the C++
  291.     // standard.
  292.     static const char* const* const _S_categories;
  293.  
  294.     // Number of standard categories. For C++, these categories are
  295.     // collate, ctype, monetary, numeric, time, and messages. These
  296.     // directly correspond to ISO C99 macros LC_COLLATE, LC_CTYPE,
  297.     // LC_MONETARY, LC_NUMERIC, and LC_TIME. In addition, POSIX (IEEE
  298.     // 1003.1-2001) specifies LC_MESSAGES.
  299.     // In addition to the standard categories, the underlying
  300.     // operating system is allowed to define extra LC_*
  301.     // macros. For GNU systems, the following are also valid:
  302.     // LC_PAPER, LC_NAME, LC_ADDRESS, LC_TELEPHONE, LC_MEASUREMENT,
  303.     // and LC_IDENTIFICATION.
  304.     enum { _S_categories_size = 6 + _GLIBCXX_NUM_CATEGORIES };
  305.  
  306. #ifdef __GTHREADS
  307.     static __gthread_once_t _S_once;
  308. #endif
  309.  
  310.     explicit
  311.     locale(_Impl*) throw();
  312.  
  313.     static void
  314.     _S_initialize();
  315.  
  316.     static void
  317.     _S_initialize_once() throw();
  318.  
  319.     static category
  320.     _S_normalize_category(category);
  321.  
  322.     void
  323.     _M_coalesce(const locale& __base, const locale& __add, category __cat);
  324.   };
  325.  
  326.  
  327.   // 22.1.1.1.2  Class locale::facet
  328.   /**
  329.    *  @brief  Localization functionality base class.
  330.    *  @ingroup locales
  331.    *
  332.    *  The facet class is the base class for a localization feature, such as
  333.    *  money, time, and number printing.  It provides common support for facets
  334.    *  and reference management.
  335.    *
  336.    *  Facets may not be copied or assigned.
  337.   */
  338.   class locale::facet
  339.   {
  340.   private:
  341.     friend class locale;
  342.     friend class locale::_Impl;
  343.  
  344.     mutable _Atomic_word                _M_refcount;
  345.  
  346.     // Contains data from the underlying "C" library for the classic locale.
  347.     static __c_locale                   _S_c_locale;
  348.  
  349.     // String literal for the name of the classic locale.
  350.     static const char                   _S_c_name[2];
  351.  
  352. #ifdef __GTHREADS
  353.     static __gthread_once_t             _S_once;
  354. #endif
  355.  
  356.     static void
  357.     _S_initialize_once();
  358.  
  359.   protected:
  360.     /**
  361.      *  @brief  Facet constructor.
  362.      *
  363.      *  This is the constructor provided by the standard.  If refs is 0, the
  364.      *  facet is destroyed when the last referencing locale is destroyed.
  365.      *  Otherwise the facet will never be destroyed.
  366.      *
  367.      *  @param __refs  The initial value for reference count.
  368.     */
  369.     explicit
  370.     facet(size_t __refs = 0) throw() : _M_refcount(__refs ? 1 : 0)
  371.     { }
  372.  
  373.     /// Facet destructor.
  374.     virtual
  375.     ~facet();
  376.  
  377.     static void
  378.     _S_create_c_locale(__c_locale& __cloc, const char* __s,
  379.                        __c_locale __old = 0);
  380.  
  381.     static __c_locale
  382.     _S_clone_c_locale(__c_locale& __cloc) throw();
  383.  
  384.     static void
  385.     _S_destroy_c_locale(__c_locale& __cloc);
  386.  
  387.     static __c_locale
  388.     _S_lc_ctype_c_locale(__c_locale __cloc, const char* __s);
  389.  
  390.     // Returns data from the underlying "C" library data for the
  391.     // classic locale.
  392.     static __c_locale
  393.     _S_get_c_locale();
  394.  
  395.     _GLIBCXX_CONST static const char*
  396.     _S_get_c_name() throw();
  397.  
  398.   private:
  399.     void
  400.     _M_add_reference() const throw()
  401.     { __gnu_cxx::__atomic_add_dispatch(&_M_refcount, 1); }
  402.  
  403.     void
  404.     _M_remove_reference() const throw()
  405.     {
  406.       // Be race-detector-friendly.  For more info see bits/c++config.
  407.       _GLIBCXX_SYNCHRONIZATION_HAPPENS_BEFORE(&_M_refcount);
  408.       if (__gnu_cxx::__exchange_and_add_dispatch(&_M_refcount, -1) == 1)
  409.         {
  410.           _GLIBCXX_SYNCHRONIZATION_HAPPENS_AFTER(&_M_refcount);
  411.           __try
  412.             { delete this; }
  413.           __catch(...)
  414.             { }
  415.         }
  416.     }
  417.  
  418.     facet(const facet&);  // Not defined.
  419.  
  420.     facet&
  421.     operator=(const facet&);  // Not defined.
  422.   };
  423.  
  424.  
  425.   // 22.1.1.1.3 Class locale::id
  426.   /**
  427.    *  @brief  Facet ID class.
  428.    *  @ingroup locales
  429.    *
  430.    *  The ID class provides facets with an index used to identify them.
  431.    *  Every facet class must define a public static member locale::id, or be
  432.    *  derived from a facet that provides this member, otherwise the facet
  433.    *  cannot be used in a locale.  The locale::id ensures that each class
  434.    *  type gets a unique identifier.
  435.   */
  436.   class locale::id
  437.   {
  438.   private:
  439.     friend class locale;
  440.     friend class locale::_Impl;
  441.  
  442.     template<typename _Facet>
  443.       friend const _Facet&
  444.       use_facet(const locale&);
  445.  
  446.     template<typename _Facet>
  447.       friend bool
  448.       has_facet(const locale&) throw();
  449.  
  450.     // NB: There is no accessor for _M_index because it may be used
  451.     // before the constructor is run; the effect of calling a member
  452.     // function (even an inline) would be undefined.
  453.     mutable size_t              _M_index;
  454.  
  455.     // Last id number assigned.
  456.     static _Atomic_word         _S_refcount;
  457.  
  458.     void
  459.     operator=(const id&);  // Not defined.
  460.  
  461.     id(const id&);  // Not defined.
  462.  
  463.   public:
  464.     // NB: This class is always a static data member, and thus can be
  465.     // counted on to be zero-initialized.
  466.     /// Constructor.
  467.     id() { }
  468.  
  469.     size_t
  470.     _M_id() const throw();
  471.   };
  472.  
  473.  
  474.   // Implementation object for locale.
  475.   class locale::_Impl
  476.   {
  477.   public:
  478.     // Friends.
  479.     friend class locale;
  480.     friend class locale::facet;
  481.  
  482.     template<typename _Facet>
  483.       friend bool
  484.       has_facet(const locale&) throw();
  485.  
  486.     template<typename _Facet>
  487.       friend const _Facet&
  488.       use_facet(const locale&);
  489.  
  490.     template<typename _Cache>
  491.       friend struct __use_cache;
  492.  
  493.   private:
  494.     // Data Members.
  495.     _Atomic_word                        _M_refcount;
  496.     const facet**                       _M_facets;
  497.     size_t                              _M_facets_size;
  498.     const facet**                       _M_caches;
  499.     char**                              _M_names;
  500.     static const locale::id* const      _S_id_ctype[];
  501.     static const locale::id* const      _S_id_numeric[];
  502.     static const locale::id* const      _S_id_collate[];
  503.     static const locale::id* const      _S_id_time[];
  504.     static const locale::id* const      _S_id_monetary[];
  505.     static const locale::id* const      _S_id_messages[];
  506.     static const locale::id* const* const _S_facet_categories[];
  507.  
  508.     void
  509.     _M_add_reference() throw()
  510.     { __gnu_cxx::__atomic_add_dispatch(&_M_refcount, 1); }
  511.  
  512.     void
  513.     _M_remove_reference() throw()
  514.     {
  515.       // Be race-detector-friendly.  For more info see bits/c++config.
  516.       _GLIBCXX_SYNCHRONIZATION_HAPPENS_BEFORE(&_M_refcount);
  517.       if (__gnu_cxx::__exchange_and_add_dispatch(&_M_refcount, -1) == 1)
  518.         {
  519.           _GLIBCXX_SYNCHRONIZATION_HAPPENS_AFTER(&_M_refcount);
  520.           __try
  521.             { delete this; }
  522.           __catch(...)
  523.             { }
  524.         }
  525.     }
  526.  
  527.     _Impl(const _Impl&, size_t);
  528.     _Impl(const char*, size_t);
  529.     _Impl(size_t) throw();
  530.  
  531.    ~_Impl() throw();
  532.  
  533.     _Impl(const _Impl&);  // Not defined.
  534.  
  535.     void
  536.     operator=(const _Impl&);  // Not defined.
  537.  
  538.     bool
  539.     _M_check_same_name()
  540.     {
  541.       bool __ret = true;
  542.       if (_M_names[1])
  543.         // We must actually compare all the _M_names: can be all equal!
  544.         for (size_t __i = 0; __ret && __i < _S_categories_size - 1; ++__i)
  545.           __ret = __builtin_strcmp(_M_names[__i], _M_names[__i + 1]) == 0;
  546.       return __ret;
  547.     }
  548.  
  549.     void
  550.     _M_replace_categories(const _Impl*, category);
  551.  
  552.     void
  553.     _M_replace_category(const _Impl*, const locale::id* const*);
  554.  
  555.     void
  556.     _M_replace_facet(const _Impl*, const locale::id*);
  557.  
  558.     void
  559.     _M_install_facet(const locale::id*, const facet*);
  560.  
  561.     template<typename _Facet>
  562.       void
  563.       _M_init_facet(_Facet* __facet)
  564.       { _M_install_facet(&_Facet::id, __facet); }
  565.  
  566.     void
  567.     _M_install_cache(const facet*, size_t);
  568.   };
  569.  
  570.  
  571.   /**
  572.    *  @brief  Facet for localized string comparison.
  573.    *
  574.    *  This facet encapsulates the code to compare strings in a localized
  575.    *  manner.
  576.    *
  577.    *  The collate template uses protected virtual functions to provide
  578.    *  the actual results.  The public accessors forward the call to
  579.    *  the virtual functions.  These virtual functions are hooks for
  580.    *  developers to implement the behavior they require from the
  581.    *  collate facet.
  582.   */
  583.   template<typename _CharT>
  584.     class collate : public locale::facet
  585.     {
  586.     public:
  587.       // Types:
  588.       //@{
  589.       /// Public typedefs
  590.       typedef _CharT                    char_type;
  591.       typedef basic_string<_CharT>      string_type;
  592.       //@}
  593.  
  594.     protected:
  595.       // Underlying "C" library locale information saved from
  596.       // initialization, needed by collate_byname as well.
  597.       __c_locale                        _M_c_locale_collate;
  598.  
  599.     public:
  600.       /// Numpunct facet id.
  601.       static locale::id                 id;
  602.  
  603.       /**
  604.        *  @brief  Constructor performs initialization.
  605.        *
  606.        *  This is the constructor provided by the standard.
  607.        *
  608.        *  @param __refs  Passed to the base facet class.
  609.       */
  610.       explicit
  611.       collate(size_t __refs = 0)
  612.       : facet(__refs), _M_c_locale_collate(_S_get_c_locale())
  613.       { }
  614.  
  615.       /**
  616.        *  @brief  Internal constructor. Not for general use.
  617.        *
  618.        *  This is a constructor for use by the library itself to set up new
  619.        *  locales.
  620.        *
  621.        *  @param __cloc  The C locale.
  622.        *  @param __refs  Passed to the base facet class.
  623.       */
  624.       explicit
  625.       collate(__c_locale __cloc, size_t __refs = 0)
  626.       : facet(__refs), _M_c_locale_collate(_S_clone_c_locale(__cloc))
  627.       { }
  628.  
  629.       /**
  630.        *  @brief  Compare two strings.
  631.        *
  632.        *  This function compares two strings and returns the result by calling
  633.        *  collate::do_compare().
  634.        *
  635.        *  @param __lo1  Start of string 1.
  636.        *  @param __hi1  End of string 1.
  637.        *  @param __lo2  Start of string 2.
  638.        *  @param __hi2  End of string 2.
  639.        *  @return  1 if string1 > string2, -1 if string1 < string2, else 0.
  640.       */
  641.       int
  642.       compare(const _CharT* __lo1, const _CharT* __hi1,
  643.               const _CharT* __lo2, const _CharT* __hi2) const
  644.       { return this->do_compare(__lo1, __hi1, __lo2, __hi2); }
  645.  
  646.       /**
  647.        *  @brief  Transform string to comparable form.
  648.        *
  649.        *  This function is a wrapper for strxfrm functionality.  It takes the
  650.        *  input string and returns a modified string that can be directly
  651.        *  compared to other transformed strings.  In the C locale, this
  652.        *  function just returns a copy of the input string.  In some other
  653.        *  locales, it may replace two chars with one, change a char for
  654.        *  another, etc.  It does so by returning collate::do_transform().
  655.        *
  656.        *  @param __lo  Start of string.
  657.        *  @param __hi  End of string.
  658.        *  @return  Transformed string_type.
  659.       */
  660.       string_type
  661.       transform(const _CharT* __lo, const _CharT* __hi) const
  662.       { return this->do_transform(__lo, __hi); }
  663.  
  664.       /**
  665.        *  @brief  Return hash of a string.
  666.        *
  667.        *  This function computes and returns a hash on the input string.  It
  668.        *  does so by returning collate::do_hash().
  669.        *
  670.        *  @param __lo  Start of string.
  671.        *  @param __hi  End of string.
  672.        *  @return  Hash value.
  673.       */
  674.       long
  675.       hash(const _CharT* __lo, const _CharT* __hi) const
  676.       { return this->do_hash(__lo, __hi); }
  677.  
  678.       // Used to abstract out _CharT bits in virtual member functions, below.
  679.       int
  680.       _M_compare(const _CharT*, const _CharT*) const throw();
  681.  
  682.       size_t
  683.       _M_transform(_CharT*, const _CharT*, size_t) const throw();
  684.  
  685.   protected:
  686.       /// Destructor.
  687.       virtual
  688.       ~collate()
  689.       { _S_destroy_c_locale(_M_c_locale_collate); }
  690.  
  691.       /**
  692.        *  @brief  Compare two strings.
  693.        *
  694.        *  This function is a hook for derived classes to change the value
  695.        *  returned.  @see compare().
  696.        *
  697.        *  @param __lo1  Start of string 1.
  698.        *  @param __hi1  End of string 1.
  699.        *  @param __lo2  Start of string 2.
  700.        *  @param __hi2  End of string 2.
  701.        *  @return  1 if string1 > string2, -1 if string1 < string2, else 0.
  702.       */
  703.       virtual int
  704.       do_compare(const _CharT* __lo1, const _CharT* __hi1,
  705.                  const _CharT* __lo2, const _CharT* __hi2) const;
  706.  
  707.       /**
  708.        *  @brief  Transform string to comparable form.
  709.        *
  710.        *  This function is a hook for derived classes to change the value
  711.        *  returned.
  712.        *
  713.        *  @param __lo  Start.
  714.        *  @param __hi  End.
  715.        *  @return  transformed string.
  716.       */
  717.       virtual string_type
  718.       do_transform(const _CharT* __lo, const _CharT* __hi) const;
  719.  
  720.       /**
  721.        *  @brief  Return hash of a string.
  722.        *
  723.        *  This function computes and returns a hash on the input string.  This
  724.        *  function is a hook for derived classes to change the value returned.
  725.        *
  726.        *  @param __lo  Start of string.
  727.        *  @param __hi  End of string.
  728.        *  @return  Hash value.
  729.       */
  730.       virtual long
  731.       do_hash(const _CharT* __lo, const _CharT* __hi) const;
  732.     };
  733.  
  734.   template<typename _CharT>
  735.     locale::id collate<_CharT>::id;
  736.  
  737.   // Specializations.
  738.   template<>
  739.     int
  740.     collate<char>::_M_compare(const char*, const char*) const throw();
  741.  
  742.   template<>
  743.     size_t
  744.     collate<char>::_M_transform(char*, const char*, size_t) const throw();
  745.  
  746. #ifdef _GLIBCXX_USE_WCHAR_T
  747.   template<>
  748.     int
  749.     collate<wchar_t>::_M_compare(const wchar_t*, const wchar_t*) const throw();
  750.  
  751.   template<>
  752.     size_t
  753.     collate<wchar_t>::_M_transform(wchar_t*, const wchar_t*, size_t) const throw();
  754. #endif
  755.  
  756.   /// class collate_byname [22.2.4.2].
  757.   template<typename _CharT>
  758.     class collate_byname : public collate<_CharT>
  759.     {
  760.     public:
  761.       //@{
  762.       /// Public typedefs
  763.       typedef _CharT               char_type;
  764.       typedef basic_string<_CharT> string_type;
  765.       //@}
  766.  
  767.       explicit
  768.       collate_byname(const char* __s, size_t __refs = 0)
  769.       : collate<_CharT>(__refs)
  770.       {
  771.         if (__builtin_strcmp(__s, "C") != 0
  772.             && __builtin_strcmp(__s, "POSIX") != 0)
  773.           {
  774.             this->_S_destroy_c_locale(this->_M_c_locale_collate);
  775.             this->_S_create_c_locale(this->_M_c_locale_collate, __s);
  776.           }
  777.       }
  778.  
  779.     protected:
  780.       virtual
  781.       ~collate_byname() { }
  782.     };
  783.  
  784. _GLIBCXX_END_NAMESPACE_VERSION
  785. } // namespace
  786.  
  787. # include <bits/locale_classes.tcc>
  788.  
  789. #endif
  790.