1// Locale support -*- C++ -*- 
2 
3// Copyright (C) 1997-2021 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#if __cpp_impl_three_way_comparison < 201907L 
258 /** 
259 * @brief Locale inequality. 
260 * 
261 * @param __other The locale to compare against. 
262 * @return ! (*this == __other) 
263 */ 
264 bool 
265 operator!=(const locale& __other) const throw() 
266 { return !(this->operator==(__other)); } 
267#endif 
268 
269 /** 
270 * @brief Compare two strings according to collate. 
271 * 
272 * Template operator to compare two strings using the compare function of 
273 * the collate facet in this locale. One use is to provide the locale to 
274 * the sort function. For example, a vector v of strings could be sorted 
275 * according to locale loc by doing: 
276 * @code 
277 * std::sort(v.begin(), v.end(), loc); 
278 * @endcode 
279 * 
280 * @param __s1 First string to compare. 
281 * @param __s2 Second string to compare. 
282 * @return True if collate<_Char> facet compares __s1 < __s2, else false. 
283 */ 
284 template<typename _Char, typename _Traits, typename _Alloc> 
285 bool 
286 operator()(const basic_string<_Char, _Traits, _Alloc>& __s1, 
287 const basic_string<_Char, _Traits, _Alloc>& __s2) const; 
288 
289 // Global locale objects: 
290 /** 
291 * @brief Set global locale 
292 * 
293 * This function sets the global locale to the argument and returns a 
294 * copy of the previous global locale. If the argument has a name, it 
295 * will also call std::setlocale(LC_ALL, loc.name()). 
296 * 
297 * @param __loc The new locale to make global. 
298 * @return Copy of the old global locale. 
299 */ 
300 static locale 
301 global(const locale& __loc); 
302 
303 /** 
304 * @brief Return reference to the C locale. 
305 */ 
306 static const locale& 
307 classic(); 
308 
309 private: 
310 // The (shared) implementation 
311 _Impl* _M_impl; 
312 
313 // The "C" reference locale 
314 static _Impl* _S_classic; 
315 
316 // Current global locale 
317 static _Impl* _S_global; 
318 
319 // Names of underlying locale categories. 
320 // NB: locale::global() has to know how to modify all the 
321 // underlying categories, not just the ones required by the C++ 
322 // standard. 
323 static const char* const* const _S_categories; 
324 
325 // Number of standard categories. For C++, these categories are 
326 // collate, ctype, monetary, numeric, time, and messages. These 
327 // directly correspond to ISO C99 macros LC_COLLATE, LC_CTYPE, 
328 // LC_MONETARY, LC_NUMERIC, and LC_TIME. In addition, POSIX (IEEE 
329 // 1003.1-2001) specifies LC_MESSAGES. 
330 // In addition to the standard categories, the underlying 
331 // operating system is allowed to define extra LC_* 
332 // macros. For GNU systems, the following are also valid: 
333 // LC_PAPER, LC_NAME, LC_ADDRESS, LC_TELEPHONE, LC_MEASUREMENT, 
334 // and LC_IDENTIFICATION. 
335 enum { _S_categories_size = 6 + _GLIBCXX_NUM_CATEGORIES }; 
336 
337#ifdef __GTHREADS 
338 static __gthread_once_t _S_once; 
339#endif 
340 
341 explicit 
342 locale(_Impl*) throw(); 
343 
344 static void 
345 _S_initialize(); 
346 
347 static void 
348 _S_initialize_once() throw(); 
349 
350 static category 
351 _S_normalize_category(category); 
352 
353 void 
354 _M_coalesce(const locale& __base, const locale& __add, category __cat); 
355 
356#if _GLIBCXX_USE_CXX11_ABI 
357 static const id* const _S_twinned_facets[]; 
358#endif 
359 }; 
360 
361 
362 // 22.1.1.1.2 Class locale::facet 
363 /** 
364 * @brief Localization functionality base class. 
365 * @ingroup locales 
366 * 
367 * The facet class is the base class for a localization feature, such as 
368 * money, time, and number printing. It provides common support for facets 
369 * and reference management. 
370 * 
371 * Facets may not be copied or assigned. 
372 */ 
373 class locale::facet 
374 { 
375 private: 
376 friend class locale; 
377 friend class locale::_Impl; 
378 
379 mutable _Atomic_word _M_refcount; 
380 
381 // Contains data from the underlying "C" library for the classic locale. 
382 static __c_locale _S_c_locale; 
383 
384 // String literal for the name of the classic locale. 
385 static const char _S_c_name[2]; 
386 
387#ifdef __GTHREADS 
388 static __gthread_once_t _S_once; 
389#endif 
390 
391 static void 
392 _S_initialize_once(); 
393 
394 protected: 
395 /** 
396 * @brief Facet constructor. 
397 * 
398 * This is the constructor provided by the standard. If refs is 0, the 
399 * facet is destroyed when the last referencing locale is destroyed. 
400 * Otherwise the facet will never be destroyed. 
401 * 
402 * @param __refs The initial value for reference count. 
403 */ 
404 explicit 
405 facet(size_t __refs = 0) throw() : _M_refcount(__refs ? 1 : 0) 
406 { } 
407 
408 /// Facet destructor. 
409 virtual 
410 ~facet(); 
411 
412 static void 
413 _S_create_c_locale(__c_locale& __cloc, const char* __s, 
414 __c_locale __old = 0); 
415 
416 static __c_locale 
417 _S_clone_c_locale(__c_locale& __cloc) throw(); 
418 
419 static void 
420 _S_destroy_c_locale(__c_locale& __cloc); 
421 
422 static __c_locale 
423 _S_lc_ctype_c_locale(__c_locale __cloc, const char* __s); 
424 
425 // Returns data from the underlying "C" library data for the 
426 // classic locale. 
427 static __c_locale 
428 _S_get_c_locale(); 
429 
430 _GLIBCXX_CONST static const char* 
431 _S_get_c_name() throw(); 
432 
433#if __cplusplus < 201103L 
434 private: 
435 facet(const facet&); // Not defined. 
436 
437 facet& 
438 operator=(const facet&); // Not defined. 
439#else 
440 facet(const facet&) = delete; 
441 
442 facet& 
443 operator=(const facet&) = delete; 
444#endif 
445 
446 private: 
447 void 
448 _M_add_reference() const throw() 
449 { __gnu_cxx::__atomic_add_dispatch(mem: &_M_refcount, val: 1); } 
450 
451 void 
452 _M_remove_reference() const throw() 
453 { 
454 // Be race-detector-friendly. For more info see bits/c++config. 
455 _GLIBCXX_SYNCHRONIZATION_HAPPENS_BEFORE(&_M_refcount); 
456 if (__gnu_cxx::__exchange_and_add_dispatch(mem: &_M_refcount, val: -1) == 1) 
457 { 
458 _GLIBCXX_SYNCHRONIZATION_HAPPENS_AFTER(&_M_refcount); 
459 __try 
460 { delete this; } 
461 __catch(...) 
462 { } 
463 } 
464 } 
465 
466 const facet* _M_sso_shim(const id*) const; 
467 const facet* _M_cow_shim(const id*) const; 
468 
469 protected: 
470 class __shim; // For internal use only. 
471 }; 
472 
473 
474 // 22.1.1.1.3 Class locale::id 
475 /** 
476 * @brief Facet ID class. 
477 * @ingroup locales 
478 * 
479 * The ID class provides facets with an index used to identify them. 
480 * Every facet class must define a public static member locale::id, or be 
481 * derived from a facet that provides this member, otherwise the facet 
482 * cannot be used in a locale. The locale::id ensures that each class 
483 * type gets a unique identifier. 
484 */ 
485 class locale::id 
486 { 
487 private: 
488 friend class locale; 
489 friend class locale::_Impl; 
490 
491 template<typename _Facet> 
492 friend const _Facet& 
493 use_facet(const locale&); 
494 
495 template<typename _Facet> 
496 friend bool 
497 has_facet(const locale&) throw(); 
498 
499 // NB: There is no accessor for _M_index because it may be used 
500 // before the constructor is run; the effect of calling a member 
501 // function (even an inline) would be undefined. 
502 mutable size_t _M_index; 
503 
504 // Last id number assigned. 
505 static _Atomic_word _S_refcount; 
506 
507 void 
508 operator=(const id&); // Not defined. 
509 
510 id(const id&); // Not defined. 
511 
512 public: 
513 // NB: This class is always a static data member, and thus can be 
514 // counted on to be zero-initialized. 
515 /// Constructor. 
516 id() { } 
517 
518 size_t 
519 _M_id() const throw(); 
520 }; 
521 
522 
523 // Implementation object for locale. 
524 class locale::_Impl 
525 { 
526 public: 
527 // Friends. 
528 friend class locale; 
529 friend class locale::facet; 
530 
531 template<typename _Facet> 
532 friend bool 
533 has_facet(const locale&) throw(); 
534 
535 template<typename _Facet> 
536 friend const _Facet& 
537 use_facet(const locale&); 
538 
539 template<typename _Cache> 
540 friend struct __use_cache; 
541 
542 private: 
543 // Data Members. 
544 _Atomic_word _M_refcount; 
545 const facet** _M_facets; 
546 size_t _M_facets_size; 
547 const facet** _M_caches; 
548 char** _M_names; 
549 static const locale::id* const _S_id_ctype[]; 
550 static const locale::id* const _S_id_numeric[]; 
551 static const locale::id* const _S_id_collate[]; 
552 static const locale::id* const _S_id_time[]; 
553 static const locale::id* const _S_id_monetary[]; 
554 static const locale::id* const _S_id_messages[]; 
555 static const locale::id* const* const _S_facet_categories[]; 
556 
557 void 
558 _M_add_reference() throw() 
559 { __gnu_cxx::__atomic_add_dispatch(mem: &_M_refcount, val: 1); } 
560 
561 void 
562 _M_remove_reference() throw() 
563 { 
564 // Be race-detector-friendly. For more info see bits/c++config. 
565 _GLIBCXX_SYNCHRONIZATION_HAPPENS_BEFORE(&_M_refcount); 
566 if (__gnu_cxx::__exchange_and_add_dispatch(mem: &_M_refcount, val: -1) == 1) 
567 { 
568 _GLIBCXX_SYNCHRONIZATION_HAPPENS_AFTER(&_M_refcount); 
569 __try 
570 { delete this; } 
571 __catch(...) 
572 { } 
573 } 
574 } 
575 
576 _Impl(const _Impl&, size_t); 
577 _Impl(const char*, size_t); 
578 _Impl(size_t) throw(); 
579 
580 ~_Impl() throw(); 
581 
582 _Impl(const _Impl&); // Not defined. 
583 
584 void 
585 operator=(const _Impl&); // Not defined. 
586 
587 bool 
588 _M_check_same_name() 
589 { 
590 bool __ret = true; 
591 if (_M_names[1]) 
592 // We must actually compare all the _M_names: can be all equal! 
593 for (size_t __i = 0; __ret && __i < _S_categories_size - 1; ++__i) 
594 __ret = __builtin_strcmp(_M_names[__i], _M_names[__i + 1]) == 0; 
595 return __ret; 
596 } 
597 
598 void 
599 _M_replace_categories(const _Impl*, category); 
600 
601 void 
602 _M_replace_category(const _Impl*, const locale::id* const*); 
603 
604 void 
605 _M_replace_facet(const _Impl*, const locale::id*); 
606 
607 void 
608 _M_install_facet(const locale::id*, const facet*); 
609 
610 template<typename _Facet> 
611 void 
612 _M_init_facet(_Facet* __facet) 
613 { _M_install_facet(&_Facet::id, __facet); } 
614 
615 template<typename _Facet> 
616 void 
617 _M_init_facet_unchecked(_Facet* __facet) 
618 { 
619 __facet->_M_add_reference(); 
620 _M_facets[_Facet::id._M_id()] = __facet; 
621 } 
622 
623 void 
624 _M_install_cache(const facet*, size_t); 
625 
626 void _M_init_extra(facet**); 
627 void _M_init_extra(void*, void*, const char*, const char*); 
628 
629#ifdef _GLIBCXX_LONG_DOUBLE_ALT128_COMPAT 
630 void _M_init_extra_ldbl128(bool); 
631#endif 
632 }; 
633 
634 
635 /** 
636 * @brief Facet for localized string comparison. 
637 * 
638 * This facet encapsulates the code to compare strings in a localized 
639 * manner. 
640 * 
641 * The collate template uses protected virtual functions to provide 
642 * the actual results. The public accessors forward the call to 
643 * the virtual functions. These virtual functions are hooks for 
644 * developers to implement the behavior they require from the 
645 * collate facet. 
646 */ 
647 template<typename _CharT> 
648 class _GLIBCXX_NAMESPACE_CXX11 collate : public locale::facet 
649 { 
650 public: 
651 // Types: 
652 ///@{ 
653 /// Public typedefs 
654 typedef _CharT char_type; 
655 typedef basic_string<_CharT> string_type; 
656 ///@} 
657 
658 protected: 
659 // Underlying "C" library locale information saved from 
660 // initialization, needed by collate_byname as well. 
661 __c_locale _M_c_locale_collate; 
662 
663 public: 
664 /// Numpunct facet id. 
665 static locale::id id; 
666 
667 /** 
668 * @brief Constructor performs initialization. 
669 * 
670 * This is the constructor provided by the standard. 
671 * 
672 * @param __refs Passed to the base facet class. 
673 */ 
674 explicit 
675 collate(size_t __refs = 0) 
676 : facet(__refs), _M_c_locale_collate(_S_get_c_locale()) 
677 { } 
678 
679 /** 
680 * @brief Internal constructor. Not for general use. 
681 * 
682 * This is a constructor for use by the library itself to set up new 
683 * locales. 
684 * 
685 * @param __cloc The C locale. 
686 * @param __refs Passed to the base facet class. 
687 */ 
688 explicit 
689 collate(__c_locale __cloc, size_t __refs = 0) 
690 : facet(__refs), _M_c_locale_collate(_S_clone_c_locale(__cloc)) 
691 { } 
692 
693 /** 
694 * @brief Compare two strings. 
695 * 
696 * This function compares two strings and returns the result by calling 
697 * collate::do_compare(). 
698 * 
699 * @param __lo1 Start of string 1. 
700 * @param __hi1 End of string 1. 
701 * @param __lo2 Start of string 2. 
702 * @param __hi2 End of string 2. 
703 * @return 1 if string1 > string2, -1 if string1 < string2, else 0. 
704 */ 
705 int 
706 compare(const _CharT* __lo1, const _CharT* __hi1, 
707 const _CharT* __lo2, const _CharT* __hi2) const 
708 { return this->do_compare(__lo1, __hi1, __lo2, __hi2); } 
709 
710 /** 
711 * @brief Transform string to comparable form. 
712 * 
713 * This function is a wrapper for strxfrm functionality. It takes the 
714 * input string and returns a modified string that can be directly 
715 * compared to other transformed strings. In the C locale, this 
716 * function just returns a copy of the input string. In some other 
717 * locales, it may replace two chars with one, change a char for 
718 * another, etc. It does so by returning collate::do_transform(). 
719 * 
720 * @param __lo Start of string. 
721 * @param __hi End of string. 
722 * @return Transformed string_type. 
723 */ 
724 string_type 
725 transform(const _CharT* __lo, const _CharT* __hi) const 
726 { return this->do_transform(__lo, __hi); } 
727 
728 /** 
729 * @brief Return hash of a string. 
730 * 
731 * This function computes and returns a hash on the input string. It 
732 * does so by returning collate::do_hash(). 
733 * 
734 * @param __lo Start of string. 
735 * @param __hi End of string. 
736 * @return Hash value. 
737 */ 
738 long 
739 hash(const _CharT* __lo, const _CharT* __hi) const 
740 { return this->do_hash(__lo, __hi); } 
741 
742 // Used to abstract out _CharT bits in virtual member functions, below. 
743 int 
744 _M_compare(const _CharT*, const _CharT*) const throw(); 
745 
746 size_t 
747 _M_transform(_CharT*, const _CharT*, size_t) const throw(); 
748 
749 protected: 
750 /// Destructor. 
751 virtual 
752 ~collate() 
753 { _S_destroy_c_locale(cloc&: _M_c_locale_collate); } 
754 
755 /** 
756 * @brief Compare two strings. 
757 * 
758 * This function is a hook for derived classes to change the value 
759 * returned. @see compare(). 
760 * 
761 * @param __lo1 Start of string 1. 
762 * @param __hi1 End of string 1. 
763 * @param __lo2 Start of string 2. 
764 * @param __hi2 End of string 2. 
765 * @return 1 if string1 > string2, -1 if string1 < string2, else 0. 
766 */ 
767 virtual int 
768 do_compare(const _CharT* __lo1, const _CharT* __hi1, 
769 const _CharT* __lo2, const _CharT* __hi2) const; 
770 
771 /** 
772 * @brief Transform string to comparable form. 
773 * 
774 * This function is a hook for derived classes to change the value 
775 * returned. 
776 * 
777 * @param __lo Start. 
778 * @param __hi End. 
779 * @return transformed string. 
780 */ 
781 virtual string_type 
782 do_transform(const _CharT* __lo, const _CharT* __hi) const; 
783 
784 /** 
785 * @brief Return hash of a string. 
786 * 
787 * This function computes and returns a hash on the input string. This 
788 * function is a hook for derived classes to change the value returned. 
789 * 
790 * @param __lo Start of string. 
791 * @param __hi End of string. 
792 * @return Hash value. 
793 */ 
794 virtual long 
795 do_hash(const _CharT* __lo, const _CharT* __hi) const; 
796 }; 
797 
798 template<typename _CharT> 
799 locale::id collate<_CharT>::id; 
800 
801 // Specializations. 
802 template<> 
803 int 
804 collate<char>::_M_compare(const char*, const char*) const throw(); 
805 
806 template<> 
807 size_t 
808 collate<char>::_M_transform(char*, const char*, size_t) const throw(); 
809 
810#ifdef _GLIBCXX_USE_WCHAR_T 
811 template<> 
812 int 
813 collate<wchar_t>::_M_compare(const wchar_t*, const wchar_t*) const throw(); 
814 
815 template<> 
816 size_t 
817 collate<wchar_t>::_M_transform(wchar_t*, const wchar_t*, size_t) const throw(); 
818#endif 
819 
820 /// class collate_byname [22.2.4.2]. 
821 template<typename _CharT> 
822 class _GLIBCXX_NAMESPACE_CXX11 collate_byname : public collate<_CharT> 
823 { 
824 public: 
825 ///@{ 
826 /// Public typedefs 
827 typedef _CharT char_type; 
828 typedef basic_string<_CharT> string_type; 
829 ///@} 
830 
831 explicit 
832 collate_byname(const char* __s, size_t __refs = 0) 
833 : collate<_CharT>(__refs) 
834 { 
835 if (__builtin_strcmp(__s, "C") != 0 
836 && __builtin_strcmp(__s, "POSIX") != 0) 
837 { 
838 this->_S_destroy_c_locale(this->_M_c_locale_collate); 
839 this->_S_create_c_locale(this->_M_c_locale_collate, __s); 
840 } 
841 } 
842 
843#if __cplusplus >= 201103L 
844 explicit 
845 collate_byname(const string& __s, size_t __refs = 0) 
846 : collate_byname(__s.c_str(), __refs) { } 
847#endif 
848 
849 protected: 
850 virtual 
851 ~collate_byname() { } 
852 }; 
853 
854_GLIBCXX_END_NAMESPACE_VERSION 
855} // namespace 
856 
857# include <bits/locale_classes.tcc> 
858 
859#endif 
860