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  1. // Locale support -*- C++ -*-
  2.  
  3. // Copyright (C) 1997-2015 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. #if __cplusplus >= 201103L
  154.     /**
  155.      *  @brief  Named locale constructor.
  156.      *
  157.      *  Constructs a copy of the named C library locale.
  158.      *
  159.      *  @param  __s  Name of the locale to construct.
  160.      *  @throw  std::runtime_error if __s is an undefined locale.
  161.     */
  162.     explicit
  163.     locale(const std::string& __s) : locale(__s.c_str()) { }
  164.  
  165.     /**
  166.      *  @brief  Construct locale with facets from another locale.
  167.      *
  168.      *  Constructs a copy of the locale @a base.  The facets specified by @a
  169.      *  cat are replaced with those from the locale named by @a s.  If base is
  170.      *  named, this locale instance will also be named.
  171.      *
  172.      *  @param  __base  The locale to copy.
  173.      *  @param  __s  Name of the locale to use facets from.
  174.      *  @param  __cat  Set of categories defining the facets to use from __s.
  175.      *  @throw  std::runtime_error if __s is an undefined locale.
  176.     */
  177.     locale(const locale& __base, const std::string& __s, category __cat)
  178.     : locale(__base, __s.c_str(), __cat) { }
  179. #endif
  180.  
  181.     /**
  182.      *  @brief  Construct locale with facets from another locale.
  183.      *
  184.      *  Constructs a copy of the locale @a base.  The facets specified by @a
  185.      *  cat are replaced with those from the locale @a add.  If @a base and @a
  186.      *  add are named, this locale instance will also be named.
  187.      *
  188.      *  @param  __base  The locale to copy.
  189.      *  @param  __add  The locale to use facets from.
  190.      *  @param  __cat  Set of categories defining the facets to use from add.
  191.     */
  192.     locale(const locale& __base, const locale& __add, category __cat);
  193.  
  194.     /**
  195.      *  @brief  Construct locale with another facet.
  196.      *
  197.      *  Constructs a copy of the locale @a __other.  The facet @a __f
  198.      *  is added to @a __other, replacing an existing facet of type
  199.      *  Facet if there is one.  If @a __f is null, this locale is a
  200.      *  copy of @a __other.
  201.      *
  202.      *  @param  __other  The locale to copy.
  203.      *  @param  __f  The facet to add in.
  204.     */
  205.     template<typename _Facet>
  206.       locale(const locale& __other, _Facet* __f);
  207.  
  208.     /// Locale destructor.
  209.     ~locale() throw();
  210.  
  211.     /**
  212.      *  @brief  Assignment operator.
  213.      *
  214.      *  Set this locale to be a copy of @a other.
  215.      *
  216.      *  @param  __other  The locale to copy.
  217.      *  @return  A reference to this locale.
  218.     */
  219.     const locale&
  220.     operator=(const locale& __other) throw();
  221.  
  222.     /**
  223.      *  @brief  Construct locale with another facet.
  224.      *
  225.      *  Constructs and returns a new copy of this locale.  Adds or replaces an
  226.      *  existing facet of type Facet from the locale @a other into the new
  227.      *  locale.
  228.      *
  229.      *  @tparam  _Facet  The facet type to copy from other
  230.      *  @param  __other  The locale to copy from.
  231.      *  @return  Newly constructed locale.
  232.      *  @throw  std::runtime_error if __other has no facet of type _Facet.
  233.     */
  234.     template<typename _Facet>
  235.       locale
  236.       combine(const locale& __other) const;
  237.  
  238.     // Locale operations:
  239.     /**
  240.      *  @brief  Return locale name.
  241.      *  @return  Locale name or "*" if unnamed.
  242.     */
  243.     _GLIBCXX_DEFAULT_ABI_TAG
  244.     string
  245.     name() const;
  246.  
  247.     /**
  248.      *  @brief  Locale equality.
  249.      *
  250.      *  @param  __other  The locale to compare against.
  251.      *  @return  True if other and this refer to the same locale instance, are
  252.      *           copies, or have the same name.  False otherwise.
  253.     */
  254.     bool
  255.     operator==(const locale& __other) const throw();
  256.  
  257.     /**
  258.      *  @brief  Locale inequality.
  259.      *
  260.      *  @param  __other  The locale to compare against.
  261.      *  @return  ! (*this == __other)
  262.     */
  263.     bool
  264.     operator!=(const locale& __other) const throw()
  265.     { return !(this->operator==(__other)); }
  266.  
  267.     /**
  268.      *  @brief  Compare two strings according to collate.
  269.      *
  270.      *  Template operator to compare two strings using the compare function of
  271.      *  the collate facet in this locale.  One use is to provide the locale to
  272.      *  the sort function.  For example, a vector v of strings could be sorted
  273.      *  according to locale loc by doing:
  274.      *  @code
  275.      *  std::sort(v.begin(), v.end(), loc);
  276.      *  @endcode
  277.      *
  278.      *  @param  __s1  First string to compare.
  279.      *  @param  __s2  Second string to compare.
  280.      *  @return  True if collate<_Char> facet compares __s1 < __s2, else false.
  281.     */
  282.     template<typename _Char, typename _Traits, typename _Alloc>
  283.       bool
  284.       operator()(const basic_string<_Char, _Traits, _Alloc>& __s1,
  285.                  const basic_string<_Char, _Traits, _Alloc>& __s2) const;
  286.  
  287.     // Global locale objects:
  288.     /**
  289.      *  @brief  Set global locale
  290.      *
  291.      *  This function sets the global locale to the argument and returns a
  292.      *  copy of the previous global locale.  If the argument has a name, it
  293.      *  will also call std::setlocale(LC_ALL, loc.name()).
  294.      *
  295.      *  @param  __loc  The new locale to make global.
  296.      *  @return  Copy of the old global locale.
  297.     */
  298.     static locale
  299.     global(const locale& __loc);
  300.  
  301.     /**
  302.      *  @brief  Return reference to the C locale.
  303.     */
  304.     static const locale&
  305.     classic();
  306.  
  307.   private:
  308.     // The (shared) implementation
  309.     _Impl*              _M_impl;
  310.  
  311.     // The "C" reference locale
  312.     static _Impl*       _S_classic;
  313.  
  314.     // Current global locale
  315.     static _Impl*       _S_global;
  316.  
  317.     // Names of underlying locale categories.
  318.     // NB: locale::global() has to know how to modify all the
  319.     // underlying categories, not just the ones required by the C++
  320.     // standard.
  321.     static const char* const* const _S_categories;
  322.  
  323.     // Number of standard categories. For C++, these categories are
  324.     // collate, ctype, monetary, numeric, time, and messages. These
  325.     // directly correspond to ISO C99 macros LC_COLLATE, LC_CTYPE,
  326.     // LC_MONETARY, LC_NUMERIC, and LC_TIME. In addition, POSIX (IEEE
  327.     // 1003.1-2001) specifies LC_MESSAGES.
  328.     // In addition to the standard categories, the underlying
  329.     // operating system is allowed to define extra LC_*
  330.     // macros. For GNU systems, the following are also valid:
  331.     // LC_PAPER, LC_NAME, LC_ADDRESS, LC_TELEPHONE, LC_MEASUREMENT,
  332.     // and LC_IDENTIFICATION.
  333.     enum { _S_categories_size = 6 + _GLIBCXX_NUM_CATEGORIES };
  334.  
  335. #ifdef __GTHREADS
  336.     static __gthread_once_t _S_once;
  337. #endif
  338.  
  339.     explicit
  340.     locale(_Impl*) throw();
  341.  
  342.     static void
  343.     _S_initialize();
  344.  
  345.     static void
  346.     _S_initialize_once() throw();
  347.  
  348.     static category
  349.     _S_normalize_category(category);
  350.  
  351.     void
  352.     _M_coalesce(const locale& __base, const locale& __add, category __cat);
  353.  
  354. #if _GLIBCXX_USE_CXX11_ABI
  355.     static const id* const _S_twinned_facets[];
  356. #endif
  357.   };
  358.  
  359.  
  360.   // 22.1.1.1.2  Class locale::facet
  361.   /**
  362.    *  @brief  Localization functionality base class.
  363.    *  @ingroup locales
  364.    *
  365.    *  The facet class is the base class for a localization feature, such as
  366.    *  money, time, and number printing.  It provides common support for facets
  367.    *  and reference management.
  368.    *
  369.    *  Facets may not be copied or assigned.
  370.   */
  371.   class locale::facet
  372.   {
  373.   private:
  374.     friend class locale;
  375.     friend class locale::_Impl;
  376.  
  377.     mutable _Atomic_word                _M_refcount;
  378.  
  379.     // Contains data from the underlying "C" library for the classic locale.
  380.     static __c_locale                   _S_c_locale;
  381.  
  382.     // String literal for the name of the classic locale.
  383.     static const char                   _S_c_name[2];
  384.  
  385. #ifdef __GTHREADS
  386.     static __gthread_once_t             _S_once;
  387. #endif
  388.  
  389.     static void
  390.     _S_initialize_once();
  391.  
  392.   protected:
  393.     /**
  394.      *  @brief  Facet constructor.
  395.      *
  396.      *  This is the constructor provided by the standard.  If refs is 0, the
  397.      *  facet is destroyed when the last referencing locale is destroyed.
  398.      *  Otherwise the facet will never be destroyed.
  399.      *
  400.      *  @param __refs  The initial value for reference count.
  401.     */
  402.     explicit
  403.     facet(size_t __refs = 0) throw() : _M_refcount(__refs ? 1 : 0)
  404.     { }
  405.  
  406.     /// Facet destructor.
  407.     virtual
  408.     ~facet();
  409.  
  410.     static void
  411.     _S_create_c_locale(__c_locale& __cloc, const char* __s,
  412.                        __c_locale __old = 0);
  413.  
  414.     static __c_locale
  415.     _S_clone_c_locale(__c_locale& __cloc) throw();
  416.  
  417.     static void
  418.     _S_destroy_c_locale(__c_locale& __cloc);
  419.  
  420.     static __c_locale
  421.     _S_lc_ctype_c_locale(__c_locale __cloc, const char* __s);
  422.  
  423.     // Returns data from the underlying "C" library data for the
  424.     // classic locale.
  425.     static __c_locale
  426.     _S_get_c_locale();
  427.  
  428.     _GLIBCXX_CONST static const char*
  429.     _S_get_c_name() throw();
  430.  
  431.   private:
  432.     void
  433.     _M_add_reference() const throw()
  434.     { __gnu_cxx::__atomic_add_dispatch(&_M_refcount, 1); }
  435.  
  436.     void
  437.     _M_remove_reference() const throw()
  438.     {
  439.       // Be race-detector-friendly.  For more info see bits/c++config.
  440.       _GLIBCXX_SYNCHRONIZATION_HAPPENS_BEFORE(&_M_refcount);
  441.       if (__gnu_cxx::__exchange_and_add_dispatch(&_M_refcount, -1) == 1)
  442.         {
  443.           _GLIBCXX_SYNCHRONIZATION_HAPPENS_AFTER(&_M_refcount);
  444.           __try
  445.             { delete this; }
  446.           __catch(...)
  447.             { }
  448.         }
  449.     }
  450.  
  451.     facet(const facet&);  // Not defined.
  452.  
  453.     facet&
  454.     operator=(const facet&);  // Not defined.
  455.  
  456.     class __shim;
  457.  
  458.     const facet* _M_sso_shim(const id*) const;
  459.     const facet* _M_cow_shim(const id*) const;
  460.   };
  461.  
  462.  
  463.   // 22.1.1.1.3 Class locale::id
  464.   /**
  465.    *  @brief  Facet ID class.
  466.    *  @ingroup locales
  467.    *
  468.    *  The ID class provides facets with an index used to identify them.
  469.    *  Every facet class must define a public static member locale::id, or be
  470.    *  derived from a facet that provides this member, otherwise the facet
  471.    *  cannot be used in a locale.  The locale::id ensures that each class
  472.    *  type gets a unique identifier.
  473.   */
  474.   class locale::id
  475.   {
  476.   private:
  477.     friend class locale;
  478.     friend class locale::_Impl;
  479.  
  480.     template<typename _Facet>
  481.       friend const _Facet&
  482.       use_facet(const locale&);
  483.  
  484.     template<typename _Facet>
  485.       friend bool
  486.       has_facet(const locale&) throw();
  487.  
  488.     // NB: There is no accessor for _M_index because it may be used
  489.     // before the constructor is run; the effect of calling a member
  490.     // function (even an inline) would be undefined.
  491.     mutable size_t              _M_index;
  492.  
  493.     // Last id number assigned.
  494.     static _Atomic_word         _S_refcount;
  495.  
  496.     void
  497.     operator=(const id&);  // Not defined.
  498.  
  499.     id(const id&);  // Not defined.
  500.  
  501.   public:
  502.     // NB: This class is always a static data member, and thus can be
  503.     // counted on to be zero-initialized.
  504.     /// Constructor.
  505.     id() { }
  506.  
  507.     size_t
  508.     _M_id() const throw();
  509.   };
  510.  
  511.  
  512.   // Implementation object for locale.
  513.   class locale::_Impl
  514.   {
  515.   public:
  516.     // Friends.
  517.     friend class locale;
  518.     friend class locale::facet;
  519.  
  520.     template<typename _Facet>
  521.       friend bool
  522.       has_facet(const locale&) throw();
  523.  
  524.     template<typename _Facet>
  525.       friend const _Facet&
  526.       use_facet(const locale&);
  527.  
  528.     template<typename _Cache>
  529.       friend struct __use_cache;
  530.  
  531.   private:
  532.     // Data Members.
  533.     _Atomic_word                        _M_refcount;
  534.     const facet**                       _M_facets;
  535.     size_t                              _M_facets_size;
  536.     const facet**                       _M_caches;
  537.     char**                              _M_names;
  538.     static const locale::id* const      _S_id_ctype[];
  539.     static const locale::id* const      _S_id_numeric[];
  540.     static const locale::id* const      _S_id_collate[];
  541.     static const locale::id* const      _S_id_time[];
  542.     static const locale::id* const      _S_id_monetary[];
  543.     static const locale::id* const      _S_id_messages[];
  544.     static const locale::id* const* const _S_facet_categories[];
  545.  
  546.     void
  547.     _M_add_reference() throw()
  548.     { __gnu_cxx::__atomic_add_dispatch(&_M_refcount, 1); }
  549.  
  550.     void
  551.     _M_remove_reference() throw()
  552.     {
  553.       // Be race-detector-friendly.  For more info see bits/c++config.
  554.       _GLIBCXX_SYNCHRONIZATION_HAPPENS_BEFORE(&_M_refcount);
  555.       if (__gnu_cxx::__exchange_and_add_dispatch(&_M_refcount, -1) == 1)
  556.         {
  557.           _GLIBCXX_SYNCHRONIZATION_HAPPENS_AFTER(&_M_refcount);
  558.           __try
  559.             { delete this; }
  560.           __catch(...)
  561.             { }
  562.         }
  563.     }
  564.  
  565.     _Impl(const _Impl&, size_t);
  566.     _Impl(const char*, size_t);
  567.     _Impl(size_t) throw();
  568.  
  569.    ~_Impl() throw();
  570.  
  571.     _Impl(const _Impl&);  // Not defined.
  572.  
  573.     void
  574.     operator=(const _Impl&);  // Not defined.
  575.  
  576.     bool
  577.     _M_check_same_name()
  578.     {
  579.       bool __ret = true;
  580.       if (_M_names[1])
  581.         // We must actually compare all the _M_names: can be all equal!
  582.         for (size_t __i = 0; __ret && __i < _S_categories_size - 1; ++__i)
  583.           __ret = __builtin_strcmp(_M_names[__i], _M_names[__i + 1]) == 0;
  584.       return __ret;
  585.     }
  586.  
  587.     void
  588.     _M_replace_categories(const _Impl*, category);
  589.  
  590.     void
  591.     _M_replace_category(const _Impl*, const locale::id* const*);
  592.  
  593.     void
  594.     _M_replace_facet(const _Impl*, const locale::id*);
  595.  
  596.     void
  597.     _M_install_facet(const locale::id*, const facet*);
  598.  
  599.     template<typename _Facet>
  600.       void
  601.       _M_init_facet(_Facet* __facet)
  602.       { _M_install_facet(&_Facet::id, __facet); }
  603.  
  604.     template<typename _Facet>
  605.       void
  606.       _M_init_facet_unchecked(_Facet* __facet)
  607.       {
  608.         __facet->_M_add_reference();
  609.         _M_facets[_Facet::id._M_id()] = __facet;
  610.       }
  611.  
  612.     void
  613.     _M_install_cache(const facet*, size_t);
  614.  
  615.     void _M_init_extra(facet**);
  616.     void _M_init_extra(void*, void*, const char*, const char*);
  617.   };
  618.  
  619.  
  620.   /**
  621.    *  @brief  Facet for localized string comparison.
  622.    *
  623.    *  This facet encapsulates the code to compare strings in a localized
  624.    *  manner.
  625.    *
  626.    *  The collate template uses protected virtual functions to provide
  627.    *  the actual results.  The public accessors forward the call to
  628.    *  the virtual functions.  These virtual functions are hooks for
  629.    *  developers to implement the behavior they require from the
  630.    *  collate facet.
  631.   */
  632.   template<typename _CharT>
  633.     class _GLIBCXX_NAMESPACE_CXX11 collate : public locale::facet
  634.     {
  635.     public:
  636.       // Types:
  637.       //@{
  638.       /// Public typedefs
  639.       typedef _CharT                    char_type;
  640.       typedef basic_string<_CharT>      string_type;
  641.       //@}
  642.  
  643.     protected:
  644.       // Underlying "C" library locale information saved from
  645.       // initialization, needed by collate_byname as well.
  646.       __c_locale                        _M_c_locale_collate;
  647.  
  648.     public:
  649.       /// Numpunct facet id.
  650.       static locale::id                 id;
  651.  
  652.       /**
  653.        *  @brief  Constructor performs initialization.
  654.        *
  655.        *  This is the constructor provided by the standard.
  656.        *
  657.        *  @param __refs  Passed to the base facet class.
  658.       */
  659.       explicit
  660.       collate(size_t __refs = 0)
  661.       : facet(__refs), _M_c_locale_collate(_S_get_c_locale())
  662.       { }
  663.  
  664.       /**
  665.        *  @brief  Internal constructor. Not for general use.
  666.        *
  667.        *  This is a constructor for use by the library itself to set up new
  668.        *  locales.
  669.        *
  670.        *  @param __cloc  The C locale.
  671.        *  @param __refs  Passed to the base facet class.
  672.       */
  673.       explicit
  674.       collate(__c_locale __cloc, size_t __refs = 0)
  675.       : facet(__refs), _M_c_locale_collate(_S_clone_c_locale(__cloc))
  676.       { }
  677.  
  678.       /**
  679.        *  @brief  Compare two strings.
  680.        *
  681.        *  This function compares two strings and returns the result by calling
  682.        *  collate::do_compare().
  683.        *
  684.        *  @param __lo1  Start of string 1.
  685.        *  @param __hi1  End of string 1.
  686.        *  @param __lo2  Start of string 2.
  687.        *  @param __hi2  End of string 2.
  688.        *  @return  1 if string1 > string2, -1 if string1 < string2, else 0.
  689.       */
  690.       int
  691.       compare(const _CharT* __lo1, const _CharT* __hi1,
  692.               const _CharT* __lo2, const _CharT* __hi2) const
  693.       { return this->do_compare(__lo1, __hi1, __lo2, __hi2); }
  694.  
  695.       /**
  696.        *  @brief  Transform string to comparable form.
  697.        *
  698.        *  This function is a wrapper for strxfrm functionality.  It takes the
  699.        *  input string and returns a modified string that can be directly
  700.        *  compared to other transformed strings.  In the C locale, this
  701.        *  function just returns a copy of the input string.  In some other
  702.        *  locales, it may replace two chars with one, change a char for
  703.        *  another, etc.  It does so by returning collate::do_transform().
  704.        *
  705.        *  @param __lo  Start of string.
  706.        *  @param __hi  End of string.
  707.        *  @return  Transformed string_type.
  708.       */
  709.       string_type
  710.       transform(const _CharT* __lo, const _CharT* __hi) const
  711.       { return this->do_transform(__lo, __hi); }
  712.  
  713.       /**
  714.        *  @brief  Return hash of a string.
  715.        *
  716.        *  This function computes and returns a hash on the input string.  It
  717.        *  does so by returning collate::do_hash().
  718.        *
  719.        *  @param __lo  Start of string.
  720.        *  @param __hi  End of string.
  721.        *  @return  Hash value.
  722.       */
  723.       long
  724.       hash(const _CharT* __lo, const _CharT* __hi) const
  725.       { return this->do_hash(__lo, __hi); }
  726.  
  727.       // Used to abstract out _CharT bits in virtual member functions, below.
  728.       int
  729.       _M_compare(const _CharT*, const _CharT*) const throw();
  730.  
  731.       size_t
  732.       _M_transform(_CharT*, const _CharT*, size_t) const throw();
  733.  
  734.   protected:
  735.       /// Destructor.
  736.       virtual
  737.       ~collate()
  738.       { _S_destroy_c_locale(_M_c_locale_collate); }
  739.  
  740.       /**
  741.        *  @brief  Compare two strings.
  742.        *
  743.        *  This function is a hook for derived classes to change the value
  744.        *  returned.  @see compare().
  745.        *
  746.        *  @param __lo1  Start of string 1.
  747.        *  @param __hi1  End of string 1.
  748.        *  @param __lo2  Start of string 2.
  749.        *  @param __hi2  End of string 2.
  750.        *  @return  1 if string1 > string2, -1 if string1 < string2, else 0.
  751.       */
  752.       virtual int
  753.       do_compare(const _CharT* __lo1, const _CharT* __hi1,
  754.                  const _CharT* __lo2, const _CharT* __hi2) const;
  755.  
  756.       /**
  757.        *  @brief  Transform string to comparable form.
  758.        *
  759.        *  This function is a hook for derived classes to change the value
  760.        *  returned.
  761.        *
  762.        *  @param __lo  Start.
  763.        *  @param __hi  End.
  764.        *  @return  transformed string.
  765.       */
  766.       virtual string_type
  767.       do_transform(const _CharT* __lo, const _CharT* __hi) const;
  768.  
  769.       /**
  770.        *  @brief  Return hash of a string.
  771.        *
  772.        *  This function computes and returns a hash on the input string.  This
  773.        *  function is a hook for derived classes to change the value returned.
  774.        *
  775.        *  @param __lo  Start of string.
  776.        *  @param __hi  End of string.
  777.        *  @return  Hash value.
  778.       */
  779.       virtual long
  780.       do_hash(const _CharT* __lo, const _CharT* __hi) const;
  781.     };
  782.  
  783.   template<typename _CharT>
  784.     locale::id collate<_CharT>::id;
  785.  
  786.   // Specializations.
  787.   template<>
  788.     int
  789.     collate<char>::_M_compare(const char*, const char*) const throw();
  790.  
  791.   template<>
  792.     size_t
  793.     collate<char>::_M_transform(char*, const char*, size_t) const throw();
  794.  
  795. #ifdef _GLIBCXX_USE_WCHAR_T
  796.   template<>
  797.     int
  798.     collate<wchar_t>::_M_compare(const wchar_t*, const wchar_t*) const throw();
  799.  
  800.   template<>
  801.     size_t
  802.     collate<wchar_t>::_M_transform(wchar_t*, const wchar_t*, size_t) const throw();
  803. #endif
  804.  
  805.   /// class collate_byname [22.2.4.2].
  806.   template<typename _CharT>
  807.     class _GLIBCXX_NAMESPACE_CXX11 collate_byname : public collate<_CharT>
  808.     {
  809.     public:
  810.       //@{
  811.       /// Public typedefs
  812.       typedef _CharT               char_type;
  813.       typedef basic_string<_CharT> string_type;
  814.       //@}
  815.  
  816.       explicit
  817.       collate_byname(const char* __s, size_t __refs = 0)
  818.       : collate<_CharT>(__refs)
  819.       {
  820.         if (__builtin_strcmp(__s, "C") != 0
  821.             && __builtin_strcmp(__s, "POSIX") != 0)
  822.           {
  823.             this->_S_destroy_c_locale(this->_M_c_locale_collate);
  824.             this->_S_create_c_locale(this->_M_c_locale_collate, __s);
  825.           }
  826.       }
  827.  
  828. #if __cplusplus >= 201103L
  829.       explicit
  830.       collate_byname(const string& __s, size_t __refs = 0)
  831.       : collate_byname(__s.c_str(), __refs) { }
  832. #endif
  833.  
  834.     protected:
  835.       virtual
  836.       ~collate_byname() { }
  837.     };
  838.  
  839. _GLIBCXX_END_NAMESPACE_VERSION
  840. } // namespace
  841.  
  842. # include <bits/locale_classes.tcc>
  843.  
  844. #endif
  845.