1 // Character Traits for use by standard string and iostream -*- C++ -*-
2 
3 // Copyright (C) 1997-2018 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/char_traits.h
26  *  This is an internal header file, included by other library headers.
27  *  Do not attempt to use it directly. @headername{string}
28  */
29 
30 //
31 // ISO C++ 14882: 21  Strings library
32 //
33 
34 #ifndef _CHAR_TRAITS_H
35 #define _CHAR_TRAITS_H 1
36 
37 #pragma GCC system_header
38 
39 #include <bits/stl_algobase.h>  // std::copy, std::fill_n
40 #include <bits/postypes.h>      // For streampos
41 #include <cwchar>               // For WEOF, wmemmove, wmemset, etc.
42 
43 #ifndef _GLIBCXX_ALWAYS_INLINE
44 #define _GLIBCXX_ALWAYS_INLINE inline __attribute__((__always_inline__))
45 #endif
46 
_GLIBCXX_VISIBILITY(default)47 namespace __gnu_cxx _GLIBCXX_VISIBILITY(default)
48 {
49 _GLIBCXX_BEGIN_NAMESPACE_VERSION
50 
51   /**
52    *  @brief  Mapping from character type to associated types.
53    *
54    *  @note This is an implementation class for the generic version
55    *  of char_traits.  It defines int_type, off_type, pos_type, and
56    *  state_type.  By default these are unsigned long, streamoff,
57    *  streampos, and mbstate_t.  Users who need a different set of
58    *  types, but who don't need to change the definitions of any function
59    *  defined in char_traits, can specialize __gnu_cxx::_Char_types
60    *  while leaving __gnu_cxx::char_traits alone. */
61   template<typename _CharT>
62     struct _Char_types
63     {
64       typedef unsigned long   int_type;
65       typedef std::streampos  pos_type;
66       typedef std::streamoff  off_type;
67       typedef std::mbstate_t  state_type;
68     };
69 
70 
71   /**
72    *  @brief  Base class used to implement std::char_traits.
73    *
74    *  @note For any given actual character type, this definition is
75    *  probably wrong.  (Most of the member functions are likely to be
76    *  right, but the int_type and state_type typedefs, and the eof()
77    *  member function, are likely to be wrong.)  The reason this class
78    *  exists is so users can specialize it.  Classes in namespace std
79    *  may not be specialized for fundamental types, but classes in
80    *  namespace __gnu_cxx may be.
81    *
82    *  See https://gcc.gnu.org/onlinedocs/libstdc++/manual/strings.html#strings.string.character_types
83    *  for advice on how to make use of this class for @a unusual character
84    *  types. Also, check out include/ext/pod_char_traits.h.
85    */
86   template<typename _CharT>
87     struct char_traits
88     {
89       typedef _CharT                                    char_type;
90       typedef typename _Char_types<_CharT>::int_type    int_type;
91       typedef typename _Char_types<_CharT>::pos_type    pos_type;
92       typedef typename _Char_types<_CharT>::off_type    off_type;
93       typedef typename _Char_types<_CharT>::state_type  state_type;
94 
95       static _GLIBCXX14_CONSTEXPR void
96       assign(char_type& __c1, const char_type& __c2)
97       { __c1 = __c2; }
98 
99       static _GLIBCXX_CONSTEXPR bool
100       eq(const char_type& __c1, const char_type& __c2)
101       { return __c1 == __c2; }
102 
103       static _GLIBCXX_CONSTEXPR bool
104       lt(const char_type& __c1, const char_type& __c2)
105       { return __c1 < __c2; }
106 
107       static _GLIBCXX14_CONSTEXPR int
108       compare(const char_type* __s1, const char_type* __s2, std::size_t __n);
109 
110       static _GLIBCXX14_CONSTEXPR std::size_t
111       length(const char_type* __s);
112 
113       static _GLIBCXX14_CONSTEXPR const char_type*
114       find(const char_type* __s, std::size_t __n, const char_type& __a);
115 
116       static char_type*
117       move(char_type* __s1, const char_type* __s2, std::size_t __n);
118 
119       static char_type*
120       copy(char_type* __s1, const char_type* __s2, std::size_t __n);
121 
122       static char_type*
123       assign(char_type* __s, std::size_t __n, char_type __a);
124 
125       static _GLIBCXX_CONSTEXPR char_type
126       to_char_type(const int_type& __c)
127       { return static_cast<char_type>(__c); }
128 
129       static _GLIBCXX_CONSTEXPR int_type
130       to_int_type(const char_type& __c)
131       { return static_cast<int_type>(__c); }
132 
133       static _GLIBCXX_CONSTEXPR bool
134       eq_int_type(const int_type& __c1, const int_type& __c2)
135       { return __c1 == __c2; }
136 
137       static _GLIBCXX_CONSTEXPR int_type
138       eof()
139       { return static_cast<int_type>(_GLIBCXX_STDIO_EOF); }
140 
141       static _GLIBCXX_CONSTEXPR int_type
142       not_eof(const int_type& __c)
143       { return !eq_int_type(__c, eof()) ? __c : to_int_type(char_type()); }
144     };
145 
146   template<typename _CharT>
147     _GLIBCXX14_CONSTEXPR int
148     char_traits<_CharT>::
149     compare(const char_type* __s1, const char_type* __s2, std::size_t __n)
150     {
151       for (std::size_t __i = 0; __i < __n; ++__i)
152 	if (lt(__s1[__i], __s2[__i]))
153 	  return -1;
154 	else if (lt(__s2[__i], __s1[__i]))
155 	  return 1;
156       return 0;
157     }
158 
159   template<typename _CharT>
160     _GLIBCXX14_CONSTEXPR std::size_t
161     char_traits<_CharT>::
162     length(const char_type* __p)
163     {
164       std::size_t __i = 0;
165       while (!eq(__p[__i], char_type()))
166         ++__i;
167       return __i;
168     }
169 
170   template<typename _CharT>
171     _GLIBCXX14_CONSTEXPR const typename char_traits<_CharT>::char_type*
172     char_traits<_CharT>::
173     find(const char_type* __s, std::size_t __n, const char_type& __a)
174     {
175       for (std::size_t __i = 0; __i < __n; ++__i)
176         if (eq(__s[__i], __a))
177           return __s + __i;
178       return 0;
179     }
180 
181   template<typename _CharT>
182     typename char_traits<_CharT>::char_type*
183     char_traits<_CharT>::
184     move(char_type* __s1, const char_type* __s2, std::size_t __n)
185     {
186       if (__n == 0)
187 	return __s1;
188       return static_cast<_CharT*>(__builtin_memmove(__s1, __s2,
189 						    __n * sizeof(char_type)));
190     }
191 
192   template<typename _CharT>
193     typename char_traits<_CharT>::char_type*
194     char_traits<_CharT>::
195     copy(char_type* __s1, const char_type* __s2, std::size_t __n)
196     {
197       // NB: Inline std::copy so no recursive dependencies.
198       std::copy(__s2, __s2 + __n, __s1);
199       return __s1;
200     }
201 
202   template<typename _CharT>
203     typename char_traits<_CharT>::char_type*
204     char_traits<_CharT>::
205     assign(char_type* __s, std::size_t __n, char_type __a)
206     {
207       // NB: Inline std::fill_n so no recursive dependencies.
208       std::fill_n(__s, __n, __a);
209       return __s;
210     }
211 
212 _GLIBCXX_END_NAMESPACE_VERSION
213 } // namespace
214 
_GLIBCXX_VISIBILITY(default)215 namespace std _GLIBCXX_VISIBILITY(default)
216 {
217 _GLIBCXX_BEGIN_NAMESPACE_VERSION
218 
219 #if __cplusplus > 201402
220 #define __cpp_lib_constexpr_char_traits 201611
221 
222   /**
223    *  @brief Determine whether the characters of a NULL-terminated
224    *  string are known at compile time.
225    *  @param  __s  The string.
226    *
227    *  Assumes that _CharT is a built-in character type.
228    */
229   template<typename _CharT>
230     static _GLIBCXX_ALWAYS_INLINE constexpr bool
231     __constant_string_p(const _CharT* __s)
232     {
233       while (__builtin_constant_p(*__s) && *__s)
234 	__s++;
235       return __builtin_constant_p(*__s);
236     }
237 
238   /**
239    *  @brief Determine whether the characters of a character array are
240    *  known at compile time.
241    *  @param  __a  The character array.
242    *  @param  __n  Number of characters.
243    *
244    *  Assumes that _CharT is a built-in character type.
245    */
246   template<typename _CharT>
247     static _GLIBCXX_ALWAYS_INLINE constexpr bool
248     __constant_char_array_p(const _CharT* __a, size_t __n)
249     {
250       size_t __i = 0;
251       while (__i < __n && __builtin_constant_p(__a[__i]))
252 	__i++;
253       return __i == __n;
254     }
255 #endif
256 
257   // 21.1
258   /**
259    *  @brief  Basis for explicit traits specializations.
260    *
261    *  @note  For any given actual character type, this definition is
262    *  probably wrong.  Since this is just a thin wrapper around
263    *  __gnu_cxx::char_traits, it is possible to achieve a more
264    *  appropriate definition by specializing __gnu_cxx::char_traits.
265    *
266    *  See https://gcc.gnu.org/onlinedocs/libstdc++/manual/strings.html#strings.string.character_types
267    *  for advice on how to make use of this class for @a unusual character
268    *  types. Also, check out include/ext/pod_char_traits.h.
269   */
270   template<class _CharT>
271     struct char_traits : public __gnu_cxx::char_traits<_CharT>
272     { };
273 
274 
275   /// 21.1.3.1  char_traits specializations
276   template<>
277     struct char_traits<char>
278     {
279       typedef char              char_type;
280       typedef int               int_type;
281       typedef streampos         pos_type;
282       typedef streamoff         off_type;
283       typedef mbstate_t         state_type;
284 
285       static _GLIBCXX17_CONSTEXPR void
286       assign(char_type& __c1, const char_type& __c2) _GLIBCXX_NOEXCEPT
287       { __c1 = __c2; }
288 
289       static _GLIBCXX_CONSTEXPR bool
290       eq(const char_type& __c1, const char_type& __c2) _GLIBCXX_NOEXCEPT
291       { return __c1 == __c2; }
292 
293       static _GLIBCXX_CONSTEXPR bool
294       lt(const char_type& __c1, const char_type& __c2) _GLIBCXX_NOEXCEPT
295       {
296 	// LWG 467.
297 	return (static_cast<unsigned char>(__c1)
298 		< static_cast<unsigned char>(__c2));
299       }
300 
301       static _GLIBCXX17_CONSTEXPR int
302       compare(const char_type* __s1, const char_type* __s2, size_t __n)
303       {
304 #if __cplusplus > 201402
305 	if (__builtin_constant_p(__n)
306 	    && __constant_char_array_p(__s1, __n)
307 	    && __constant_char_array_p(__s2, __n))
308 	  {
309 	    for (size_t __i = 0; __i < __n; ++__i)
310 	      if (lt(__s1[__i], __s2[__i]))
311 		return -1;
312 	      else if (lt(__s2[__i], __s1[__i]))
313 		return 1;
314 	    return 0;
315 	  }
316 #endif
317 	if (__n == 0)
318 	  return 0;
319 	return __builtin_memcmp(__s1, __s2, __n);
320       }
321 
322       static _GLIBCXX17_CONSTEXPR size_t
323       length(const char_type* __s)
324       {
325 #if __cplusplus > 201402
326 	if (__constant_string_p(__s))
327 	  return __gnu_cxx::char_traits<char_type>::length(__s);
328 #endif
329 	return __builtin_strlen(__s);
330       }
331 
332       static _GLIBCXX17_CONSTEXPR const char_type*
333       find(const char_type* __s, size_t __n, const char_type& __a)
334       {
335 #if __cplusplus > 201402
336 	if (__builtin_constant_p(__n)
337 	    && __builtin_constant_p(__a)
338 	    && __constant_char_array_p(__s, __n))
339 	  return __gnu_cxx::char_traits<char_type>::find(__s, __n, __a);
340 #endif
341 	if (__n == 0)
342 	  return 0;
343 	return static_cast<const char_type*>(__builtin_memchr(__s, __a, __n));
344       }
345 
346       static char_type*
347       move(char_type* __s1, const char_type* __s2, size_t __n)
348       {
349 	if (__n == 0)
350 	  return __s1;
351 	return static_cast<char_type*>(__builtin_memmove(__s1, __s2, __n));
352       }
353 
354       static char_type*
355       copy(char_type* __s1, const char_type* __s2, size_t __n)
356       {
357 	if (__n == 0)
358 	  return __s1;
359 	return static_cast<char_type*>(__builtin_memcpy(__s1, __s2, __n));
360       }
361 
362       static char_type*
363       assign(char_type* __s, size_t __n, char_type __a)
364       {
365 	if (__n == 0)
366 	  return __s;
367 	return static_cast<char_type*>(__builtin_memset(__s, __a, __n));
368       }
369 
370       static _GLIBCXX_CONSTEXPR char_type
371       to_char_type(const int_type& __c) _GLIBCXX_NOEXCEPT
372       { return static_cast<char_type>(__c); }
373 
374       // To keep both the byte 0xff and the eof symbol 0xffffffff
375       // from ending up as 0xffffffff.
376       static _GLIBCXX_CONSTEXPR int_type
377       to_int_type(const char_type& __c) _GLIBCXX_NOEXCEPT
378       { return static_cast<int_type>(static_cast<unsigned char>(__c)); }
379 
380       static _GLIBCXX_CONSTEXPR bool
381       eq_int_type(const int_type& __c1, const int_type& __c2) _GLIBCXX_NOEXCEPT
382       { return __c1 == __c2; }
383 
384       static _GLIBCXX_CONSTEXPR int_type
385       eof() _GLIBCXX_NOEXCEPT
386       { return static_cast<int_type>(_GLIBCXX_STDIO_EOF); }
387 
388       static _GLIBCXX_CONSTEXPR int_type
389       not_eof(const int_type& __c) _GLIBCXX_NOEXCEPT
390       { return (__c == eof()) ? 0 : __c; }
391   };
392 
393 
394 #ifdef _GLIBCXX_USE_WCHAR_T
395   /// 21.1.3.2  char_traits specializations
396   template<>
397     struct char_traits<wchar_t>
398     {
399       typedef wchar_t           char_type;
400       typedef wint_t            int_type;
401       typedef streamoff         off_type;
402       typedef wstreampos        pos_type;
403       typedef mbstate_t         state_type;
404 
405       static _GLIBCXX17_CONSTEXPR void
406       assign(char_type& __c1, const char_type& __c2) _GLIBCXX_NOEXCEPT
407       { __c1 = __c2; }
408 
409       static _GLIBCXX_CONSTEXPR bool
410       eq(const char_type& __c1, const char_type& __c2) _GLIBCXX_NOEXCEPT
411       { return __c1 == __c2; }
412 
413       static _GLIBCXX_CONSTEXPR bool
414       lt(const char_type& __c1, const char_type& __c2) _GLIBCXX_NOEXCEPT
415       { return __c1 < __c2; }
416 
417       static _GLIBCXX17_CONSTEXPR int
418       compare(const char_type* __s1, const char_type* __s2, size_t __n)
419       {
420 #if __cplusplus > 201402
421 	if (__builtin_constant_p(__n)
422 	    && __constant_char_array_p(__s1, __n)
423 	    && __constant_char_array_p(__s2, __n))
424 	  return __gnu_cxx::char_traits<char_type>::compare(__s1, __s2, __n);
425 #endif
426 	if (__n == 0)
427 	  return 0;
428 	else
429 	  return wmemcmp(__s1, __s2, __n);
430       }
431 
432       static _GLIBCXX17_CONSTEXPR size_t
433       length(const char_type* __s)
434       {
435 #if __cplusplus > 201402
436 	if (__constant_string_p(__s))
437 	  return __gnu_cxx::char_traits<char_type>::length(__s);
438 	else
439 #endif
440 	  return wcslen(__s);
441       }
442 
443       static _GLIBCXX17_CONSTEXPR const char_type*
444       find(const char_type* __s, size_t __n, const char_type& __a)
445       {
446 #if __cplusplus > 201402
447 	if (__builtin_constant_p(__n)
448 	    && __builtin_constant_p(__a)
449 	    && __constant_char_array_p(__s, __n))
450 	  return __gnu_cxx::char_traits<char_type>::find(__s, __n, __a);
451 #endif
452 	if (__n == 0)
453 	  return 0;
454 	else
455 	  return wmemchr(__s, __a, __n);
456       }
457 
458       static char_type*
459       move(char_type* __s1, const char_type* __s2, size_t __n)
460       {
461 	if (__n == 0)
462 	  return __s1;
463 	return wmemmove(__s1, __s2, __n);
464       }
465 
466       static char_type*
467       copy(char_type* __s1, const char_type* __s2, size_t __n)
468       {
469 	if (__n == 0)
470 	  return __s1;
471 	return wmemcpy(__s1, __s2, __n);
472       }
473 
474       static char_type*
475       assign(char_type* __s, size_t __n, char_type __a)
476       {
477 	if (__n == 0)
478 	  return __s;
479 	return wmemset(__s, __a, __n);
480       }
481 
482       static _GLIBCXX_CONSTEXPR char_type
483       to_char_type(const int_type& __c) _GLIBCXX_NOEXCEPT
484       { return char_type(__c); }
485 
486       static _GLIBCXX_CONSTEXPR int_type
487       to_int_type(const char_type& __c) _GLIBCXX_NOEXCEPT
488       { return int_type(__c); }
489 
490       static _GLIBCXX_CONSTEXPR bool
491       eq_int_type(const int_type& __c1, const int_type& __c2) _GLIBCXX_NOEXCEPT
492       { return __c1 == __c2; }
493 
494       static _GLIBCXX_CONSTEXPR int_type
495       eof() _GLIBCXX_NOEXCEPT
496       { return static_cast<int_type>(WEOF); }
497 
498       static _GLIBCXX_CONSTEXPR int_type
499       not_eof(const int_type& __c) _GLIBCXX_NOEXCEPT
500       { return eq_int_type(__c, eof()) ? 0 : __c; }
501   };
502 #endif //_GLIBCXX_USE_WCHAR_T
503 
504 _GLIBCXX_END_NAMESPACE_VERSION
505 } // namespace
506 
507 #if ((__cplusplus >= 201103L) \
508      && defined(_GLIBCXX_USE_C99_STDINT_TR1))
509 
510 #include <cstdint>
511 
512 namespace std _GLIBCXX_VISIBILITY(default)
513 {
514 _GLIBCXX_BEGIN_NAMESPACE_VERSION
515 
516   template<>
517     struct char_traits<char16_t>
518     {
519       typedef char16_t          char_type;
520       typedef uint_least16_t    int_type;
521       typedef streamoff         off_type;
522       typedef u16streampos      pos_type;
523       typedef mbstate_t         state_type;
524 
525       static _GLIBCXX17_CONSTEXPR void
526       assign(char_type& __c1, const char_type& __c2) noexcept
527       { __c1 = __c2; }
528 
529       static constexpr bool
530       eq(const char_type& __c1, const char_type& __c2) noexcept
531       { return __c1 == __c2; }
532 
533       static constexpr bool
534       lt(const char_type& __c1, const char_type& __c2) noexcept
535       { return __c1 < __c2; }
536 
537       static _GLIBCXX17_CONSTEXPR int
538       compare(const char_type* __s1, const char_type* __s2, size_t __n)
539       {
540 	for (size_t __i = 0; __i < __n; ++__i)
541 	  if (lt(__s1[__i], __s2[__i]))
542 	    return -1;
543 	  else if (lt(__s2[__i], __s1[__i]))
544 	    return 1;
545 	return 0;
546       }
547 
548       static _GLIBCXX17_CONSTEXPR size_t
549       length(const char_type* __s)
550       {
551 	size_t __i = 0;
552 	while (!eq(__s[__i], char_type()))
553 	  ++__i;
554 	return __i;
555       }
556 
557       static _GLIBCXX17_CONSTEXPR const char_type*
558       find(const char_type* __s, size_t __n, const char_type& __a)
559       {
560 	for (size_t __i = 0; __i < __n; ++__i)
561 	  if (eq(__s[__i], __a))
562 	    return __s + __i;
563 	return 0;
564       }
565 
566       static char_type*
567       move(char_type* __s1, const char_type* __s2, size_t __n)
568       {
569 	if (__n == 0)
570 	  return __s1;
571 	return (static_cast<char_type*>
572 		(__builtin_memmove(__s1, __s2, __n * sizeof(char_type))));
573       }
574 
575       static char_type*
576       copy(char_type* __s1, const char_type* __s2, size_t __n)
577       {
578 	if (__n == 0)
579 	  return __s1;
580 	return (static_cast<char_type*>
581 		(__builtin_memcpy(__s1, __s2, __n * sizeof(char_type))));
582       }
583 
584       static char_type*
585       assign(char_type* __s, size_t __n, char_type __a)
586       {
587 	for (size_t __i = 0; __i < __n; ++__i)
588 	  assign(__s[__i], __a);
589 	return __s;
590       }
591 
592       static constexpr char_type
593       to_char_type(const int_type& __c) noexcept
594       { return char_type(__c); }
595 
596       static constexpr int_type
597       to_int_type(const char_type& __c) noexcept
598       { return __c == eof() ? int_type(0xfffd) : int_type(__c); }
599 
600       static constexpr bool
601       eq_int_type(const int_type& __c1, const int_type& __c2) noexcept
602       { return __c1 == __c2; }
603 
604       static constexpr int_type
605       eof() noexcept
606       { return static_cast<int_type>(-1); }
607 
608       static constexpr int_type
609       not_eof(const int_type& __c) noexcept
610       { return eq_int_type(__c, eof()) ? 0 : __c; }
611     };
612 
613   template<>
614     struct char_traits<char32_t>
615     {
616       typedef char32_t          char_type;
617       typedef uint_least32_t    int_type;
618       typedef streamoff         off_type;
619       typedef u32streampos      pos_type;
620       typedef mbstate_t         state_type;
621 
622       static _GLIBCXX17_CONSTEXPR void
623       assign(char_type& __c1, const char_type& __c2) noexcept
624       { __c1 = __c2; }
625 
626       static constexpr bool
627       eq(const char_type& __c1, const char_type& __c2) noexcept
628       { return __c1 == __c2; }
629 
630       static constexpr bool
631       lt(const char_type& __c1, const char_type& __c2) noexcept
632       { return __c1 < __c2; }
633 
634       static _GLIBCXX17_CONSTEXPR int
635       compare(const char_type* __s1, const char_type* __s2, size_t __n)
636       {
637 	for (size_t __i = 0; __i < __n; ++__i)
638 	  if (lt(__s1[__i], __s2[__i]))
639 	    return -1;
640 	  else if (lt(__s2[__i], __s1[__i]))
641 	    return 1;
642 	return 0;
643       }
644 
645       static _GLIBCXX17_CONSTEXPR size_t
646       length(const char_type* __s)
647       {
648 	size_t __i = 0;
649 	while (!eq(__s[__i], char_type()))
650 	  ++__i;
651 	return __i;
652       }
653 
654       static _GLIBCXX17_CONSTEXPR const char_type*
655       find(const char_type* __s, size_t __n, const char_type& __a)
656       {
657 	for (size_t __i = 0; __i < __n; ++__i)
658 	  if (eq(__s[__i], __a))
659 	    return __s + __i;
660 	return 0;
661       }
662 
663       static char_type*
664       move(char_type* __s1, const char_type* __s2, size_t __n)
665       {
666 	if (__n == 0)
667 	  return __s1;
668 	return (static_cast<char_type*>
669 		(__builtin_memmove(__s1, __s2, __n * sizeof(char_type))));
670       }
671 
672       static char_type*
673       copy(char_type* __s1, const char_type* __s2, size_t __n)
674       {
675 	if (__n == 0)
676 	  return __s1;
677 	return (static_cast<char_type*>
678 		(__builtin_memcpy(__s1, __s2, __n * sizeof(char_type))));
679       }
680 
681       static char_type*
682       assign(char_type* __s, size_t __n, char_type __a)
683       {
684 	for (size_t __i = 0; __i < __n; ++__i)
685 	  assign(__s[__i], __a);
686 	return __s;
687       }
688 
689       static constexpr char_type
690       to_char_type(const int_type& __c) noexcept
691       { return char_type(__c); }
692 
693       static constexpr int_type
694       to_int_type(const char_type& __c) noexcept
695       { return int_type(__c); }
696 
697       static constexpr bool
698       eq_int_type(const int_type& __c1, const int_type& __c2) noexcept
699       { return __c1 == __c2; }
700 
701       static constexpr int_type
702       eof() noexcept
703       { return static_cast<int_type>(-1); }
704 
705       static constexpr int_type
706       not_eof(const int_type& __c) noexcept
707       { return eq_int_type(__c, eof()) ? 0 : __c; }
708     };
709 
710 _GLIBCXX_END_NAMESPACE_VERSION
711 } // namespace
712 
713 #endif
714 
715 #endif // _CHAR_TRAITS_H
716