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
43namespace 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