libstdc++
locale_classes.h
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00001 // Locale support -*- C++ -*-
00002 
00003 // Copyright (C) 1997-2013 Free Software Foundation, Inc.
00004 //
00005 // This file is part of the GNU ISO C++ Library.  This library is free
00006 // software; you can redistribute it and/or modify it under the
00007 // terms of the GNU General Public License as published by the
00008 // Free Software Foundation; either version 3, or (at your option)
00009 // any later version.
00010 
00011 // This library is distributed in the hope that it will be useful,
00012 // but WITHOUT ANY WARRANTY; without even the implied warranty of
00013 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
00014 // GNU General Public License for more details.
00015 
00016 // Under Section 7 of GPL version 3, you are granted additional
00017 // permissions described in the GCC Runtime Library Exception, version
00018 // 3.1, as published by the Free Software Foundation.
00019 
00020 // You should have received a copy of the GNU General Public License and
00021 // a copy of the GCC Runtime Library Exception along with this program;
00022 // see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
00023 // <http://www.gnu.org/licenses/>.
00024 
00025 /** @file bits/locale_classes.h
00026  *  This is an internal header file, included by other library headers.
00027  *  Do not attempt to use it directly. @headername{locale}
00028  */
00029 
00030 //
00031 // ISO C++ 14882: 22.1  Locales
00032 //
00033 
00034 #ifndef _LOCALE_CLASSES_H
00035 #define _LOCALE_CLASSES_H 1
00036 
00037 #pragma GCC system_header
00038 
00039 #include <bits/localefwd.h>
00040 #include <string>
00041 #include <ext/atomicity.h>
00042 
00043 namespace std _GLIBCXX_VISIBILITY(default)
00044 {
00045 _GLIBCXX_BEGIN_NAMESPACE_VERSION
00046 
00047   // 22.1.1 Class locale
00048   /**
00049    *  @brief  Container class for localization functionality.
00050    *  @ingroup locales
00051    *
00052    *  The locale class is first a class wrapper for C library locales.  It is
00053    *  also an extensible container for user-defined localization.  A locale is
00054    *  a collection of facets that implement various localization features such
00055    *  as money, time, and number printing.
00056    *
00057    *  Constructing C++ locales does not change the C library locale.
00058    *
00059    *  This library supports efficient construction and copying of locales
00060    *  through a reference counting implementation of the locale class.
00061   */
00062   class locale
00063   {
00064   public:
00065     // Types:
00066     /// Definition of locale::category.
00067     typedef int category;
00068 
00069     // Forward decls and friends:
00070     class facet;
00071     class id;
00072     class _Impl;
00073 
00074     friend class facet;
00075     friend class _Impl;
00076 
00077     template<typename _Facet>
00078       friend bool
00079       has_facet(const locale&) throw();
00080 
00081     template<typename _Facet>
00082       friend const _Facet&
00083       use_facet(const locale&);
00084 
00085     template<typename _Cache>
00086       friend struct __use_cache;
00087 
00088     //@{
00089     /**
00090      *  @brief  Category values.
00091      *
00092      *  The standard category values are none, ctype, numeric, collate, time,
00093      *  monetary, and messages.  They form a bitmask that supports union and
00094      *  intersection.  The category all is the union of these values.
00095      *
00096      *  NB: Order must match _S_facet_categories definition in locale.cc
00097     */
00098     static const category none      = 0;
00099     static const category ctype     = 1L << 0;
00100     static const category numeric   = 1L << 1;
00101     static const category collate   = 1L << 2;
00102     static const category time      = 1L << 3;
00103     static const category monetary  = 1L << 4;
00104     static const category messages  = 1L << 5;
00105     static const category all       = (ctype | numeric | collate |
00106                        time  | monetary | messages);
00107     //@}
00108 
00109     // Construct/copy/destroy:
00110 
00111     /**
00112      *  @brief  Default constructor.
00113      *
00114      *  Constructs a copy of the global locale.  If no locale has been
00115      *  explicitly set, this is the C locale.
00116     */
00117     locale() throw();
00118 
00119     /**
00120      *  @brief  Copy constructor.
00121      *
00122      *  Constructs a copy of @a other.
00123      *
00124      *  @param  __other  The locale to copy.
00125     */
00126     locale(const locale& __other) throw();
00127 
00128     /**
00129      *  @brief  Named locale constructor.
00130      *
00131      *  Constructs a copy of the named C library locale.
00132      *
00133      *  @param  __s  Name of the locale to construct.
00134      *  @throw  std::runtime_error if __s is null or an undefined locale.
00135     */
00136     explicit
00137     locale(const char* __s);
00138 
00139     /**
00140      *  @brief  Construct locale with facets from another locale.
00141      *
00142      *  Constructs a copy of the locale @a base.  The facets specified by @a
00143      *  cat are replaced with those from the locale named by @a s.  If base is
00144      *  named, this locale instance will also be named.
00145      *
00146      *  @param  __base  The locale to copy.
00147      *  @param  __s  Name of the locale to use facets from.
00148      *  @param  __cat  Set of categories defining the facets to use from __s.
00149      *  @throw  std::runtime_error if __s is null or an undefined locale.
00150     */
00151     locale(const locale& __base, const char* __s, category __cat);
00152 
00153     /**
00154      *  @brief  Construct locale with facets from another locale.
00155      *
00156      *  Constructs a copy of the locale @a base.  The facets specified by @a
00157      *  cat are replaced with those from the locale @a add.  If @a base and @a
00158      *  add are named, this locale instance will also be named.
00159      *
00160      *  @param  __base  The locale to copy.
00161      *  @param  __add  The locale to use facets from.
00162      *  @param  __cat  Set of categories defining the facets to use from add.
00163     */
00164     locale(const locale& __base, const locale& __add, category __cat);
00165 
00166     /**
00167      *  @brief  Construct locale with another facet.
00168      *
00169      *  Constructs a copy of the locale @a __other.  The facet @a __f
00170      *  is added to @a __other, replacing an existing facet of type
00171      *  Facet if there is one.  If @a __f is null, this locale is a
00172      *  copy of @a __other.
00173      *
00174      *  @param  __other  The locale to copy.
00175      *  @param  __f  The facet to add in.
00176     */
00177     template<typename _Facet>
00178       locale(const locale& __other, _Facet* __f);
00179 
00180     /// Locale destructor.
00181     ~locale() throw();
00182 
00183     /**
00184      *  @brief  Assignment operator.
00185      *
00186      *  Set this locale to be a copy of @a other.
00187      *
00188      *  @param  __other  The locale to copy.
00189      *  @return  A reference to this locale.
00190     */
00191     const locale&
00192     operator=(const locale& __other) throw();
00193 
00194     /**
00195      *  @brief  Construct locale with another facet.
00196      *
00197      *  Constructs and returns a new copy of this locale.  Adds or replaces an
00198      *  existing facet of type Facet from the locale @a other into the new
00199      *  locale.
00200      *
00201      *  @tparam  _Facet  The facet type to copy from other
00202      *  @param  __other  The locale to copy from.
00203      *  @return  Newly constructed locale.
00204      *  @throw  std::runtime_error if __other has no facet of type _Facet.
00205     */
00206     template<typename _Facet>
00207       locale
00208       combine(const locale& __other) const;
00209 
00210     // Locale operations:
00211     /**
00212      *  @brief  Return locale name.
00213      *  @return  Locale name or "*" if unnamed.
00214     */
00215     string
00216     name() const;
00217 
00218     /**
00219      *  @brief  Locale equality.
00220      *
00221      *  @param  __other  The locale to compare against.
00222      *  @return  True if other and this refer to the same locale instance, are
00223      *       copies, or have the same name.  False otherwise.
00224     */
00225     bool
00226     operator==(const locale& __other) const throw();
00227 
00228     /**
00229      *  @brief  Locale inequality.
00230      *
00231      *  @param  __other  The locale to compare against.
00232      *  @return  ! (*this == __other)
00233     */
00234     bool
00235     operator!=(const locale& __other) const throw()
00236     { return !(this->operator==(__other)); }
00237 
00238     /**
00239      *  @brief  Compare two strings according to collate.
00240      *
00241      *  Template operator to compare two strings using the compare function of
00242      *  the collate facet in this locale.  One use is to provide the locale to
00243      *  the sort function.  For example, a vector v of strings could be sorted
00244      *  according to locale loc by doing:
00245      *  @code
00246      *  std::sort(v.begin(), v.end(), loc);
00247      *  @endcode
00248      *
00249      *  @param  __s1  First string to compare.
00250      *  @param  __s2  Second string to compare.
00251      *  @return  True if collate<_Char> facet compares __s1 < __s2, else false.
00252     */
00253     template<typename _Char, typename _Traits, typename _Alloc>
00254       bool
00255       operator()(const basic_string<_Char, _Traits, _Alloc>& __s1,
00256          const basic_string<_Char, _Traits, _Alloc>& __s2) const;
00257 
00258     // Global locale objects:
00259     /**
00260      *  @brief  Set global locale
00261      *
00262      *  This function sets the global locale to the argument and returns a
00263      *  copy of the previous global locale.  If the argument has a name, it
00264      *  will also call std::setlocale(LC_ALL, loc.name()).
00265      *
00266      *  @param  __loc  The new locale to make global.
00267      *  @return  Copy of the old global locale.
00268     */
00269     static locale
00270     global(const locale& __loc);
00271 
00272     /**
00273      *  @brief  Return reference to the C locale.
00274     */
00275     static const locale&
00276     classic();
00277 
00278   private:
00279     // The (shared) implementation
00280     _Impl*      _M_impl;
00281 
00282     // The "C" reference locale
00283     static _Impl*       _S_classic;
00284 
00285     // Current global locale
00286     static _Impl*   _S_global;
00287 
00288     // Names of underlying locale categories.
00289     // NB: locale::global() has to know how to modify all the
00290     // underlying categories, not just the ones required by the C++
00291     // standard.
00292     static const char* const* const _S_categories;
00293 
00294     // Number of standard categories. For C++, these categories are
00295     // collate, ctype, monetary, numeric, time, and messages. These
00296     // directly correspond to ISO C99 macros LC_COLLATE, LC_CTYPE,
00297     // LC_MONETARY, LC_NUMERIC, and LC_TIME. In addition, POSIX (IEEE
00298     // 1003.1-2001) specifies LC_MESSAGES.
00299     // In addition to the standard categories, the underlying
00300     // operating system is allowed to define extra LC_*
00301     // macros. For GNU systems, the following are also valid:
00302     // LC_PAPER, LC_NAME, LC_ADDRESS, LC_TELEPHONE, LC_MEASUREMENT,
00303     // and LC_IDENTIFICATION.
00304     enum { _S_categories_size = 6 + _GLIBCXX_NUM_CATEGORIES };
00305 
00306 #ifdef __GTHREADS
00307     static __gthread_once_t _S_once;
00308 #endif
00309 
00310     explicit
00311     locale(_Impl*) throw();
00312 
00313     static void
00314     _S_initialize();
00315 
00316     static void
00317     _S_initialize_once() throw();
00318 
00319     static category
00320     _S_normalize_category(category);
00321 
00322     void
00323     _M_coalesce(const locale& __base, const locale& __add, category __cat);
00324   };
00325 
00326 
00327   // 22.1.1.1.2  Class locale::facet
00328   /**
00329    *  @brief  Localization functionality base class.
00330    *  @ingroup locales
00331    *
00332    *  The facet class is the base class for a localization feature, such as
00333    *  money, time, and number printing.  It provides common support for facets
00334    *  and reference management.
00335    *
00336    *  Facets may not be copied or assigned.
00337   */
00338   class locale::facet
00339   {
00340   private:
00341     friend class locale;
00342     friend class locale::_Impl;
00343 
00344     mutable _Atomic_word        _M_refcount;
00345 
00346     // Contains data from the underlying "C" library for the classic locale.
00347     static __c_locale                   _S_c_locale;
00348 
00349     // String literal for the name of the classic locale.
00350     static const char           _S_c_name[2];
00351 
00352 #ifdef __GTHREADS
00353     static __gthread_once_t     _S_once;
00354 #endif
00355 
00356     static void
00357     _S_initialize_once();
00358 
00359   protected:
00360     /**
00361      *  @brief  Facet constructor.
00362      *
00363      *  This is the constructor provided by the standard.  If refs is 0, the
00364      *  facet is destroyed when the last referencing locale is destroyed.
00365      *  Otherwise the facet will never be destroyed.
00366      *
00367      *  @param __refs  The initial value for reference count.
00368     */
00369     explicit
00370     facet(size_t __refs = 0) throw() : _M_refcount(__refs ? 1 : 0)
00371     { }
00372 
00373     /// Facet destructor.
00374     virtual
00375     ~facet();
00376 
00377     static void
00378     _S_create_c_locale(__c_locale& __cloc, const char* __s,
00379                __c_locale __old = 0);
00380 
00381     static __c_locale
00382     _S_clone_c_locale(__c_locale& __cloc) throw();
00383 
00384     static void
00385     _S_destroy_c_locale(__c_locale& __cloc);
00386 
00387     static __c_locale
00388     _S_lc_ctype_c_locale(__c_locale __cloc, const char* __s);
00389 
00390     // Returns data from the underlying "C" library data for the
00391     // classic locale.
00392     static __c_locale
00393     _S_get_c_locale();
00394 
00395     _GLIBCXX_CONST static const char*
00396     _S_get_c_name() throw();
00397 
00398   private:
00399     void
00400     _M_add_reference() const throw()
00401     { __gnu_cxx::__atomic_add_dispatch(&_M_refcount, 1); }
00402 
00403     void
00404     _M_remove_reference() const throw()
00405     {
00406       // Be race-detector-friendly.  For more info see bits/c++config.
00407       _GLIBCXX_SYNCHRONIZATION_HAPPENS_BEFORE(&_M_refcount);
00408       if (__gnu_cxx::__exchange_and_add_dispatch(&_M_refcount, -1) == 1)
00409     {
00410           _GLIBCXX_SYNCHRONIZATION_HAPPENS_AFTER(&_M_refcount);
00411       __try
00412         { delete this; }
00413       __catch(...)
00414         { }
00415     }
00416     }
00417 
00418     facet(const facet&);  // Not defined.
00419 
00420     facet&
00421     operator=(const facet&);  // Not defined.
00422   };
00423 
00424 
00425   // 22.1.1.1.3 Class locale::id
00426   /**
00427    *  @brief  Facet ID class.
00428    *  @ingroup locales
00429    *
00430    *  The ID class provides facets with an index used to identify them.
00431    *  Every facet class must define a public static member locale::id, or be
00432    *  derived from a facet that provides this member, otherwise the facet
00433    *  cannot be used in a locale.  The locale::id ensures that each class
00434    *  type gets a unique identifier.
00435   */
00436   class locale::id
00437   {
00438   private:
00439     friend class locale;
00440     friend class locale::_Impl;
00441 
00442     template<typename _Facet>
00443       friend const _Facet&
00444       use_facet(const locale&);
00445 
00446     template<typename _Facet>
00447       friend bool
00448       has_facet(const locale&) throw();
00449 
00450     // NB: There is no accessor for _M_index because it may be used
00451     // before the constructor is run; the effect of calling a member
00452     // function (even an inline) would be undefined.
00453     mutable size_t      _M_index;
00454 
00455     // Last id number assigned.
00456     static _Atomic_word     _S_refcount;
00457 
00458     void
00459     operator=(const id&);  // Not defined.
00460 
00461     id(const id&);  // Not defined.
00462 
00463   public:
00464     // NB: This class is always a static data member, and thus can be
00465     // counted on to be zero-initialized.
00466     /// Constructor.
00467     id() { }
00468 
00469     size_t
00470     _M_id() const throw();
00471   };
00472 
00473 
00474   // Implementation object for locale.
00475   class locale::_Impl
00476   {
00477   public:
00478     // Friends.
00479     friend class locale;
00480     friend class locale::facet;
00481 
00482     template<typename _Facet>
00483       friend bool
00484       has_facet(const locale&) throw();
00485 
00486     template<typename _Facet>
00487       friend const _Facet&
00488       use_facet(const locale&);
00489 
00490     template<typename _Cache>
00491       friend struct __use_cache;
00492 
00493   private:
00494     // Data Members.
00495     _Atomic_word            _M_refcount;
00496     const facet**           _M_facets;
00497     size_t              _M_facets_size;
00498     const facet**           _M_caches;
00499     char**              _M_names;
00500     static const locale::id* const  _S_id_ctype[];
00501     static const locale::id* const  _S_id_numeric[];
00502     static const locale::id* const  _S_id_collate[];
00503     static const locale::id* const  _S_id_time[];
00504     static const locale::id* const  _S_id_monetary[];
00505     static const locale::id* const  _S_id_messages[];
00506     static const locale::id* const* const _S_facet_categories[];
00507 
00508     void
00509     _M_add_reference() throw()
00510     { __gnu_cxx::__atomic_add_dispatch(&_M_refcount, 1); }
00511 
00512     void
00513     _M_remove_reference() throw()
00514     {
00515       // Be race-detector-friendly.  For more info see bits/c++config.
00516       _GLIBCXX_SYNCHRONIZATION_HAPPENS_BEFORE(&_M_refcount);
00517       if (__gnu_cxx::__exchange_and_add_dispatch(&_M_refcount, -1) == 1)
00518     {
00519           _GLIBCXX_SYNCHRONIZATION_HAPPENS_AFTER(&_M_refcount);
00520       __try
00521         { delete this; }
00522       __catch(...)
00523         { }
00524     }
00525     }
00526 
00527     _Impl(const _Impl&, size_t);
00528     _Impl(const char*, size_t);
00529     _Impl(size_t) throw();
00530 
00531    ~_Impl() throw();
00532 
00533     _Impl(const _Impl&);  // Not defined.
00534 
00535     void
00536     operator=(const _Impl&);  // Not defined.
00537 
00538     bool
00539     _M_check_same_name()
00540     {
00541       bool __ret = true;
00542       if (_M_names[1])
00543     // We must actually compare all the _M_names: can be all equal!
00544     for (size_t __i = 0; __ret && __i < _S_categories_size - 1; ++__i)
00545       __ret = __builtin_strcmp(_M_names[__i], _M_names[__i + 1]) == 0;
00546       return __ret;
00547     }
00548 
00549     void
00550     _M_replace_categories(const _Impl*, category);
00551 
00552     void
00553     _M_replace_category(const _Impl*, const locale::id* const*);
00554 
00555     void
00556     _M_replace_facet(const _Impl*, const locale::id*);
00557 
00558     void
00559     _M_install_facet(const locale::id*, const facet*);
00560 
00561     template<typename _Facet>
00562       void
00563       _M_init_facet(_Facet* __facet)
00564       { _M_install_facet(&_Facet::id, __facet); }
00565 
00566     void
00567     _M_install_cache(const facet*, size_t);
00568   };
00569 
00570 
00571   /**
00572    *  @brief  Facet for localized string comparison.
00573    *
00574    *  This facet encapsulates the code to compare strings in a localized
00575    *  manner.
00576    *
00577    *  The collate template uses protected virtual functions to provide
00578    *  the actual results.  The public accessors forward the call to
00579    *  the virtual functions.  These virtual functions are hooks for
00580    *  developers to implement the behavior they require from the
00581    *  collate facet.
00582   */
00583   template<typename _CharT>
00584     class collate : public locale::facet
00585     {
00586     public:
00587       // Types:
00588       //@{
00589       /// Public typedefs
00590       typedef _CharT            char_type;
00591       typedef basic_string<_CharT>  string_type;
00592       //@}
00593 
00594     protected:
00595       // Underlying "C" library locale information saved from
00596       // initialization, needed by collate_byname as well.
00597       __c_locale            _M_c_locale_collate;
00598 
00599     public:
00600       /// Numpunct facet id.
00601       static locale::id         id;
00602 
00603       /**
00604        *  @brief  Constructor performs initialization.
00605        *
00606        *  This is the constructor provided by the standard.
00607        *
00608        *  @param __refs  Passed to the base facet class.
00609       */
00610       explicit
00611       collate(size_t __refs = 0)
00612       : facet(__refs), _M_c_locale_collate(_S_get_c_locale())
00613       { }
00614 
00615       /**
00616        *  @brief  Internal constructor. Not for general use.
00617        *
00618        *  This is a constructor for use by the library itself to set up new
00619        *  locales.
00620        *
00621        *  @param __cloc  The C locale.
00622        *  @param __refs  Passed to the base facet class.
00623       */
00624       explicit
00625       collate(__c_locale __cloc, size_t __refs = 0)
00626       : facet(__refs), _M_c_locale_collate(_S_clone_c_locale(__cloc))
00627       { }
00628 
00629       /**
00630        *  @brief  Compare two strings.
00631        *
00632        *  This function compares two strings and returns the result by calling
00633        *  collate::do_compare().
00634        *
00635        *  @param __lo1  Start of string 1.
00636        *  @param __hi1  End of string 1.
00637        *  @param __lo2  Start of string 2.
00638        *  @param __hi2  End of string 2.
00639        *  @return  1 if string1 > string2, -1 if string1 < string2, else 0.
00640       */
00641       int
00642       compare(const _CharT* __lo1, const _CharT* __hi1,
00643           const _CharT* __lo2, const _CharT* __hi2) const
00644       { return this->do_compare(__lo1, __hi1, __lo2, __hi2); }
00645 
00646       /**
00647        *  @brief  Transform string to comparable form.
00648        *
00649        *  This function is a wrapper for strxfrm functionality.  It takes the
00650        *  input string and returns a modified string that can be directly
00651        *  compared to other transformed strings.  In the C locale, this
00652        *  function just returns a copy of the input string.  In some other
00653        *  locales, it may replace two chars with one, change a char for
00654        *  another, etc.  It does so by returning collate::do_transform().
00655        *
00656        *  @param __lo  Start of string.
00657        *  @param __hi  End of string.
00658        *  @return  Transformed string_type.
00659       */
00660       string_type
00661       transform(const _CharT* __lo, const _CharT* __hi) const
00662       { return this->do_transform(__lo, __hi); }
00663 
00664       /**
00665        *  @brief  Return hash of a string.
00666        *
00667        *  This function computes and returns a hash on the input string.  It
00668        *  does so by returning collate::do_hash().
00669        *
00670        *  @param __lo  Start of string.
00671        *  @param __hi  End of string.
00672        *  @return  Hash value.
00673       */
00674       long
00675       hash(const _CharT* __lo, const _CharT* __hi) const
00676       { return this->do_hash(__lo, __hi); }
00677 
00678       // Used to abstract out _CharT bits in virtual member functions, below.
00679       int
00680       _M_compare(const _CharT*, const _CharT*) const throw();
00681 
00682       size_t
00683       _M_transform(_CharT*, const _CharT*, size_t) const throw();
00684 
00685   protected:
00686       /// Destructor.
00687       virtual
00688       ~collate()
00689       { _S_destroy_c_locale(_M_c_locale_collate); }
00690 
00691       /**
00692        *  @brief  Compare two strings.
00693        *
00694        *  This function is a hook for derived classes to change the value
00695        *  returned.  @see compare().
00696        *
00697        *  @param __lo1  Start of string 1.
00698        *  @param __hi1  End of string 1.
00699        *  @param __lo2  Start of string 2.
00700        *  @param __hi2  End of string 2.
00701        *  @return  1 if string1 > string2, -1 if string1 < string2, else 0.
00702       */
00703       virtual int
00704       do_compare(const _CharT* __lo1, const _CharT* __hi1,
00705          const _CharT* __lo2, const _CharT* __hi2) const;
00706 
00707       /**
00708        *  @brief  Transform string to comparable form.
00709        *
00710        *  This function is a hook for derived classes to change the value
00711        *  returned.
00712        *
00713        *  @param __lo  Start.
00714        *  @param __hi  End.
00715        *  @return  transformed string.
00716       */
00717       virtual string_type
00718       do_transform(const _CharT* __lo, const _CharT* __hi) const;
00719 
00720       /**
00721        *  @brief  Return hash of a string.
00722        *
00723        *  This function computes and returns a hash on the input string.  This
00724        *  function is a hook for derived classes to change the value returned.
00725        *
00726        *  @param __lo  Start of string.
00727        *  @param __hi  End of string.
00728        *  @return  Hash value.
00729       */
00730       virtual long
00731       do_hash(const _CharT* __lo, const _CharT* __hi) const;
00732     };
00733 
00734   template<typename _CharT>
00735     locale::id collate<_CharT>::id;
00736 
00737   // Specializations.
00738   template<>
00739     int
00740     collate<char>::_M_compare(const char*, const char*) const throw();
00741 
00742   template<>
00743     size_t
00744     collate<char>::_M_transform(char*, const char*, size_t) const throw();
00745 
00746 #ifdef _GLIBCXX_USE_WCHAR_T
00747   template<>
00748     int
00749     collate<wchar_t>::_M_compare(const wchar_t*, const wchar_t*) const throw();
00750 
00751   template<>
00752     size_t
00753     collate<wchar_t>::_M_transform(wchar_t*, const wchar_t*, size_t) const throw();
00754 #endif
00755 
00756   /// class collate_byname [22.2.4.2].
00757   template<typename _CharT>
00758     class collate_byname : public collate<_CharT>
00759     {
00760     public:
00761       //@{
00762       /// Public typedefs
00763       typedef _CharT               char_type;
00764       typedef basic_string<_CharT> string_type;
00765       //@}
00766 
00767       explicit
00768       collate_byname(const char* __s, size_t __refs = 0)
00769       : collate<_CharT>(__refs)
00770       {
00771     if (__builtin_strcmp(__s, "C") != 0
00772         && __builtin_strcmp(__s, "POSIX") != 0)
00773       {
00774         this->_S_destroy_c_locale(this->_M_c_locale_collate);
00775         this->_S_create_c_locale(this->_M_c_locale_collate, __s);
00776       }
00777       }
00778 
00779     protected:
00780       virtual
00781       ~collate_byname() { }
00782     };
00783 
00784 _GLIBCXX_END_NAMESPACE_VERSION
00785 } // namespace
00786 
00787 # include <bits/locale_classes.tcc>
00788 
00789 #endif