xref: /netbsd-src/external/gpl3/gcc/dist/libstdc++-v3/include/bits/locale_classes.h (revision 3f4ceed98fffd10d8f2ada3ccdb32adaf619f42c)
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     const facet* _M_sso_shim(const id*) const;
457     const facet* _M_cow_shim(const id*) const;
458 
459   protected:
460     class __shim; // For internal use only.
461   };
462 
463 
464   // 22.1.1.1.3 Class locale::id
465   /**
466    *  @brief  Facet ID class.
467    *  @ingroup locales
468    *
469    *  The ID class provides facets with an index used to identify them.
470    *  Every facet class must define a public static member locale::id, or be
471    *  derived from a facet that provides this member, otherwise the facet
472    *  cannot be used in a locale.  The locale::id ensures that each class
473    *  type gets a unique identifier.
474   */
475   class locale::id
476   {
477   private:
478     friend class locale;
479     friend class locale::_Impl;
480 
481     template<typename _Facet>
482       friend const _Facet&
483       use_facet(const locale&);
484 
485     template<typename _Facet>
486       friend bool
487       has_facet(const locale&) throw();
488 
489     // NB: There is no accessor for _M_index because it may be used
490     // before the constructor is run; the effect of calling a member
491     // function (even an inline) would be undefined.
492     mutable size_t		_M_index;
493 
494     // Last id number assigned.
495     static _Atomic_word		_S_refcount;
496 
497     void
498     operator=(const id&);  // Not defined.
499 
500     id(const id&);  // Not defined.
501 
502   public:
503     // NB: This class is always a static data member, and thus can be
504     // counted on to be zero-initialized.
505     /// Constructor.
506     id() { }
507 
508     size_t
509     _M_id() const throw();
510   };
511 
512 
513   // Implementation object for locale.
514   class locale::_Impl
515   {
516   public:
517     // Friends.
518     friend class locale;
519     friend class locale::facet;
520 
521     template<typename _Facet>
522       friend bool
523       has_facet(const locale&) throw();
524 
525     template<typename _Facet>
526       friend const _Facet&
527       use_facet(const locale&);
528 
529     template<typename _Cache>
530       friend struct __use_cache;
531 
532   private:
533     // Data Members.
534     _Atomic_word			_M_refcount;
535     const facet**			_M_facets;
536     size_t				_M_facets_size;
537     const facet**			_M_caches;
538     char**				_M_names;
539     static const locale::id* const	_S_id_ctype[];
540     static const locale::id* const	_S_id_numeric[];
541     static const locale::id* const	_S_id_collate[];
542     static const locale::id* const	_S_id_time[];
543     static const locale::id* const	_S_id_monetary[];
544     static const locale::id* const	_S_id_messages[];
545     static const locale::id* const* const _S_facet_categories[];
546 
547     void
548     _M_add_reference() throw()
549     { __gnu_cxx::__atomic_add_dispatch(&_M_refcount, 1); }
550 
551     void
552     _M_remove_reference() throw()
553     {
554       // Be race-detector-friendly.  For more info see bits/c++config.
555       _GLIBCXX_SYNCHRONIZATION_HAPPENS_BEFORE(&_M_refcount);
556       if (__gnu_cxx::__exchange_and_add_dispatch(&_M_refcount, -1) == 1)
557 	{
558           _GLIBCXX_SYNCHRONIZATION_HAPPENS_AFTER(&_M_refcount);
559 	  __try
560 	    { delete this; }
561 	  __catch(...)
562 	    { }
563 	}
564     }
565 
566     _Impl(const _Impl&, size_t);
567     _Impl(const char*, size_t);
568     _Impl(size_t) throw();
569 
570    ~_Impl() throw();
571 
572     _Impl(const _Impl&);  // Not defined.
573 
574     void
575     operator=(const _Impl&);  // Not defined.
576 
577     bool
578     _M_check_same_name()
579     {
580       bool __ret = true;
581       if (_M_names[1])
582 	// We must actually compare all the _M_names: can be all equal!
583 	for (size_t __i = 0; __ret && __i < _S_categories_size - 1; ++__i)
584 	  __ret = __builtin_strcmp(_M_names[__i], _M_names[__i + 1]) == 0;
585       return __ret;
586     }
587 
588     void
589     _M_replace_categories(const _Impl*, category);
590 
591     void
592     _M_replace_category(const _Impl*, const locale::id* const*);
593 
594     void
595     _M_replace_facet(const _Impl*, const locale::id*);
596 
597     void
598     _M_install_facet(const locale::id*, const facet*);
599 
600     template<typename _Facet>
601       void
602       _M_init_facet(_Facet* __facet)
603       { _M_install_facet(&_Facet::id, __facet); }
604 
605     template<typename _Facet>
606       void
607       _M_init_facet_unchecked(_Facet* __facet)
608       {
609 	__facet->_M_add_reference();
610 	_M_facets[_Facet::id._M_id()] = __facet;
611       }
612 
613     void
614     _M_install_cache(const facet*, size_t);
615 
616     void _M_init_extra(facet**);
617     void _M_init_extra(void*, void*, const char*, const char*);
618   };
619 
620 
621   /**
622    *  @brief  Facet for localized string comparison.
623    *
624    *  This facet encapsulates the code to compare strings in a localized
625    *  manner.
626    *
627    *  The collate template uses protected virtual functions to provide
628    *  the actual results.  The public accessors forward the call to
629    *  the virtual functions.  These virtual functions are hooks for
630    *  developers to implement the behavior they require from the
631    *  collate facet.
632   */
633   template<typename _CharT>
634     class _GLIBCXX_NAMESPACE_CXX11 collate : public locale::facet
635     {
636     public:
637       // Types:
638       //@{
639       /// Public typedefs
640       typedef _CharT			char_type;
641       typedef basic_string<_CharT>	string_type;
642       //@}
643 
644     protected:
645       // Underlying "C" library locale information saved from
646       // initialization, needed by collate_byname as well.
647       __c_locale			_M_c_locale_collate;
648 
649     public:
650       /// Numpunct facet id.
651       static locale::id			id;
652 
653       /**
654        *  @brief  Constructor performs initialization.
655        *
656        *  This is the constructor provided by the standard.
657        *
658        *  @param __refs  Passed to the base facet class.
659       */
660       explicit
661       collate(size_t __refs = 0)
662       : facet(__refs), _M_c_locale_collate(_S_get_c_locale())
663       { }
664 
665       /**
666        *  @brief  Internal constructor. Not for general use.
667        *
668        *  This is a constructor for use by the library itself to set up new
669        *  locales.
670        *
671        *  @param __cloc  The C locale.
672        *  @param __refs  Passed to the base facet class.
673       */
674       explicit
675       collate(__c_locale __cloc, size_t __refs = 0)
676       : facet(__refs), _M_c_locale_collate(_S_clone_c_locale(__cloc))
677       { }
678 
679       /**
680        *  @brief  Compare two strings.
681        *
682        *  This function compares two strings and returns the result by calling
683        *  collate::do_compare().
684        *
685        *  @param __lo1  Start of string 1.
686        *  @param __hi1  End of string 1.
687        *  @param __lo2  Start of string 2.
688        *  @param __hi2  End of string 2.
689        *  @return  1 if string1 > string2, -1 if string1 < string2, else 0.
690       */
691       int
692       compare(const _CharT* __lo1, const _CharT* __hi1,
693 	      const _CharT* __lo2, const _CharT* __hi2) const
694       { return this->do_compare(__lo1, __hi1, __lo2, __hi2); }
695 
696       /**
697        *  @brief  Transform string to comparable form.
698        *
699        *  This function is a wrapper for strxfrm functionality.  It takes the
700        *  input string and returns a modified string that can be directly
701        *  compared to other transformed strings.  In the C locale, this
702        *  function just returns a copy of the input string.  In some other
703        *  locales, it may replace two chars with one, change a char for
704        *  another, etc.  It does so by returning collate::do_transform().
705        *
706        *  @param __lo  Start of string.
707        *  @param __hi  End of string.
708        *  @return  Transformed string_type.
709       */
710       string_type
711       transform(const _CharT* __lo, const _CharT* __hi) const
712       { return this->do_transform(__lo, __hi); }
713 
714       /**
715        *  @brief  Return hash of a string.
716        *
717        *  This function computes and returns a hash on the input string.  It
718        *  does so by returning collate::do_hash().
719        *
720        *  @param __lo  Start of string.
721        *  @param __hi  End of string.
722        *  @return  Hash value.
723       */
724       long
725       hash(const _CharT* __lo, const _CharT* __hi) const
726       { return this->do_hash(__lo, __hi); }
727 
728       // Used to abstract out _CharT bits in virtual member functions, below.
729       int
730       _M_compare(const _CharT*, const _CharT*) const throw();
731 
732       size_t
733       _M_transform(_CharT*, const _CharT*, size_t) const throw();
734 
735   protected:
736       /// Destructor.
737       virtual
738       ~collate()
739       { _S_destroy_c_locale(_M_c_locale_collate); }
740 
741       /**
742        *  @brief  Compare two strings.
743        *
744        *  This function is a hook for derived classes to change the value
745        *  returned.  @see compare().
746        *
747        *  @param __lo1  Start of string 1.
748        *  @param __hi1  End of string 1.
749        *  @param __lo2  Start of string 2.
750        *  @param __hi2  End of string 2.
751        *  @return  1 if string1 > string2, -1 if string1 < string2, else 0.
752       */
753       virtual int
754       do_compare(const _CharT* __lo1, const _CharT* __hi1,
755 		 const _CharT* __lo2, const _CharT* __hi2) const;
756 
757       /**
758        *  @brief  Transform string to comparable form.
759        *
760        *  This function is a hook for derived classes to change the value
761        *  returned.
762        *
763        *  @param __lo  Start.
764        *  @param __hi  End.
765        *  @return  transformed string.
766       */
767       virtual string_type
768       do_transform(const _CharT* __lo, const _CharT* __hi) const;
769 
770       /**
771        *  @brief  Return hash of a string.
772        *
773        *  This function computes and returns a hash on the input string.  This
774        *  function is a hook for derived classes to change the value returned.
775        *
776        *  @param __lo  Start of string.
777        *  @param __hi  End of string.
778        *  @return  Hash value.
779       */
780       virtual long
781       do_hash(const _CharT* __lo, const _CharT* __hi) const;
782     };
783 
784   template<typename _CharT>
785     locale::id collate<_CharT>::id;
786 
787   // Specializations.
788   template<>
789     int
790     collate<char>::_M_compare(const char*, const char*) const throw();
791 
792   template<>
793     size_t
794     collate<char>::_M_transform(char*, const char*, size_t) const throw();
795 
796 #ifdef _GLIBCXX_USE_WCHAR_T
797   template<>
798     int
799     collate<wchar_t>::_M_compare(const wchar_t*, const wchar_t*) const throw();
800 
801   template<>
802     size_t
803     collate<wchar_t>::_M_transform(wchar_t*, const wchar_t*, size_t) const throw();
804 #endif
805 
806   /// class collate_byname [22.2.4.2].
807   template<typename _CharT>
808     class _GLIBCXX_NAMESPACE_CXX11 collate_byname : public collate<_CharT>
809     {
810     public:
811       //@{
812       /// Public typedefs
813       typedef _CharT               char_type;
814       typedef basic_string<_CharT> string_type;
815       //@}
816 
817       explicit
818       collate_byname(const char* __s, size_t __refs = 0)
819       : collate<_CharT>(__refs)
820       {
821 	if (__builtin_strcmp(__s, "C") != 0
822 	    && __builtin_strcmp(__s, "POSIX") != 0)
823 	  {
824 	    this->_S_destroy_c_locale(this->_M_c_locale_collate);
825 	    this->_S_create_c_locale(this->_M_c_locale_collate, __s);
826 	  }
827       }
828 
829 #if __cplusplus >= 201103L
830       explicit
831       collate_byname(const string& __s, size_t __refs = 0)
832       : collate_byname(__s.c_str(), __refs) { }
833 #endif
834 
835     protected:
836       virtual
837       ~collate_byname() { }
838     };
839 
840 _GLIBCXX_END_NAMESPACE_VERSION
841 } // namespace
842 
843 # include <bits/locale_classes.tcc>
844 
845 #endif
846