1// Character Traits for use by standard string and iostream -*- 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/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#if __cplusplus > 201703L
43# include <compare>
44#endif
45
46#ifndef _GLIBCXX_ALWAYS_INLINE
47# define _GLIBCXX_ALWAYS_INLINE inline __attribute__((__always_inline__))
48#endif
49
50namespace __gnu_cxx _GLIBCXX_VISIBILITY(default)
51{
52_GLIBCXX_BEGIN_NAMESPACE_VERSION
53
54 /**
55 * @brief Mapping from character type to associated types.
56 *
57 * @note This is an implementation class for the generic version
58 * of char_traits. It defines int_type, off_type, pos_type, and
59 * state_type. By default these are unsigned long, streamoff,
60 * streampos, and mbstate_t. Users who need a different set of
61 * types, but who don't need to change the definitions of any function
62 * defined in char_traits, can specialize __gnu_cxx::_Char_types
63 * while leaving __gnu_cxx::char_traits alone. */
64 template<typename _CharT>
65 struct _Char_types
66 {
67 typedef unsigned long int_type;
68 typedef std::streampos pos_type;
69 typedef std::streamoff off_type;
70 typedef std::mbstate_t state_type;
71 };
72
73
74 /**
75 * @brief Base class used to implement std::char_traits.
76 *
77 * @note For any given actual character type, this definition is
78 * probably wrong. (Most of the member functions are likely to be
79 * right, but the int_type and state_type typedefs, and the eof()
80 * member function, are likely to be wrong.) The reason this class
81 * exists is so users can specialize it. Classes in namespace std
82 * may not be specialized for fundamental types, but classes in
83 * namespace __gnu_cxx may be.
84 *
85 * See https://gcc.gnu.org/onlinedocs/libstdc++/manual/strings.html#strings.string.character_types
86 * for advice on how to make use of this class for @a unusual character
87 * types. Also, check out include/ext/pod_char_traits.h.
88 */
89 template<typename _CharT>
90 struct char_traits
91 {
92 typedef _CharT char_type;
93 typedef typename _Char_types<_CharT>::int_type int_type;
94 typedef typename _Char_types<_CharT>::pos_type pos_type;
95 typedef typename _Char_types<_CharT>::off_type off_type;
96 typedef typename _Char_types<_CharT>::state_type state_type;
97#if __cpp_lib_three_way_comparison
98 using comparison_category = std::strong_ordering;
99#endif
100
101 static _GLIBCXX14_CONSTEXPR void
102 assign(char_type& __c1, const char_type& __c2)
103 { __c1 = __c2; }
104
105 static _GLIBCXX_CONSTEXPR bool
106 eq(const char_type& __c1, const char_type& __c2)
107 { return __c1 == __c2; }
108
109 static _GLIBCXX_CONSTEXPR bool
110 lt(const char_type& __c1, const char_type& __c2)
111 { return __c1 < __c2; }
112
113 static _GLIBCXX14_CONSTEXPR int
114 compare(const char_type* __s1, const char_type* __s2, std::size_t __n);
115
116 static _GLIBCXX14_CONSTEXPR std::size_t
117 length(const char_type* __s);
118
119 static _GLIBCXX14_CONSTEXPR const char_type*
120 find(const char_type* __s, std::size_t __n, const char_type& __a);
121
122 static _GLIBCXX20_CONSTEXPR char_type*
123 move(char_type* __s1, const char_type* __s2, std::size_t __n);
124
125 static _GLIBCXX20_CONSTEXPR char_type*
126 copy(char_type* __s1, const char_type* __s2, std::size_t __n);
127
128 static _GLIBCXX20_CONSTEXPR char_type*
129 assign(char_type* __s, std::size_t __n, char_type __a);
130
131 static _GLIBCXX_CONSTEXPR char_type
132 to_char_type(const int_type& __c)
133 { return static_cast<char_type>(__c); }
134
135 static _GLIBCXX_CONSTEXPR int_type
136 to_int_type(const char_type& __c)
137 { return static_cast<int_type>(__c); }
138
139 static _GLIBCXX_CONSTEXPR bool
140 eq_int_type(const int_type& __c1, const int_type& __c2)
141 { return __c1 == __c2; }
142
143 static _GLIBCXX_CONSTEXPR int_type
144 eof()
145 { return static_cast<int_type>(_GLIBCXX_STDIO_EOF); }
146
147 static _GLIBCXX_CONSTEXPR int_type
148 not_eof(const int_type& __c)
149 { return !eq_int_type(c1: __c, c2: eof()) ? __c : to_int_type(c: char_type()); }
150 };
151
152 template<typename _CharT>
153 _GLIBCXX14_CONSTEXPR int
154 char_traits<_CharT>::
155 compare(const char_type* __s1, const char_type* __s2, std::size_t __n)
156 {
157 for (std::size_t __i = 0; __i < __n; ++__i)
158 if (lt(c1: __s1[__i], c2: __s2[__i]))
159 return -1;
160 else if (lt(c1: __s2[__i], c2: __s1[__i]))
161 return 1;
162 return 0;
163 }
164
165 template<typename _CharT>
166 _GLIBCXX14_CONSTEXPR std::size_t
167 char_traits<_CharT>::
168 length(const char_type* __p)
169 {
170 std::size_t __i = 0;
171 while (!eq(c1: __p[__i], c2: char_type()))
172 ++__i;
173 return __i;
174 }
175
176 template<typename _CharT>
177 _GLIBCXX14_CONSTEXPR const typename char_traits<_CharT>::char_type*
178 char_traits<_CharT>::
179 find(const char_type* __s, std::size_t __n, const char_type& __a)
180 {
181 for (std::size_t __i = 0; __i < __n; ++__i)
182 if (eq(c1: __s[__i], c2: __a))
183 return __s + __i;
184 return 0;
185 }
186
187 template<typename _CharT>
188 _GLIBCXX20_CONSTEXPR
189 typename char_traits<_CharT>::char_type*
190 char_traits<_CharT>::
191 move(char_type* __s1, const char_type* __s2, std::size_t __n)
192 {
193 if (__n == 0)
194 return __s1;
195#if __cpp_lib_is_constant_evaluated
196 if (std::is_constant_evaluated())
197 {
198 if (__s1 == __s2) // unlikely, but saves a lot of work
199 return __s1;
200#if __cpp_constexpr_dynamic_alloc
201 // The overlap detection below fails due to PR c++/89074,
202 // so use a temporary buffer instead.
203 char_type* __tmp = new char_type[__n];
204 copy(__tmp, __s2, __n);
205 copy(__s1, __tmp, __n);
206 delete[] __tmp;
207#else
208 const auto __end = __s2 + __n - 1;
209 bool __overlap = false;
210 for (std::size_t __i = 0; __i < __n - 1; ++__i)
211 {
212 if (__s1 + __i == __end)
213 {
214 __overlap = true;
215 break;
216 }
217 }
218 if (__overlap)
219 {
220 do
221 {
222 --__n;
223 assign(__s1[__n], __s2[__n]);
224 }
225 while (__n > 0);
226 }
227 else
228 copy(__s1, __s2, __n);
229#endif
230 return __s1;
231 }
232#endif
233 __builtin_memmove(__s1, __s2, __n * sizeof(char_type));
234 return __s1;
235 }
236
237 template<typename _CharT>
238 _GLIBCXX20_CONSTEXPR
239 typename char_traits<_CharT>::char_type*
240 char_traits<_CharT>::
241 copy(char_type* __s1, const char_type* __s2, std::size_t __n)
242 {
243 // NB: Inline std::copy so no recursive dependencies.
244 std::copy(__s2, __s2 + __n, __s1);
245 return __s1;
246 }
247
248 template<typename _CharT>
249 _GLIBCXX20_CONSTEXPR
250 typename char_traits<_CharT>::char_type*
251 char_traits<_CharT>::
252 assign(char_type* __s, std::size_t __n, char_type __a)
253 {
254 // NB: Inline std::fill_n so no recursive dependencies.
255 std::fill_n(__s, __n, __a);
256 return __s;
257 }
258
259_GLIBCXX_END_NAMESPACE_VERSION
260} // namespace
261
262namespace std _GLIBCXX_VISIBILITY(default)
263{
264_GLIBCXX_BEGIN_NAMESPACE_VERSION
265
266#if __cplusplus >= 201703L
267
268#ifdef __cpp_lib_is_constant_evaluated
269// Unofficial macro indicating P1032R1 support in C++20
270# define __cpp_lib_constexpr_char_traits 201811L
271#else
272// Unofficial macro indicating P0426R1 support in C++17
273# define __cpp_lib_constexpr_char_traits 201611L
274#endif
275
276 /**
277 * @brief Determine whether the characters of a NULL-terminated
278 * string are known at compile time.
279 * @param __s The string.
280 *
281 * Assumes that _CharT is a built-in character type.
282 */
283 template<typename _CharT>
284 _GLIBCXX_ALWAYS_INLINE constexpr bool
285 __constant_string_p(const _CharT* __s)
286 {
287#ifdef _GLIBCXX_HAVE_BUILTIN_IS_CONSTANT_EVALUATED
288 (void) __s;
289 // In constexpr contexts all strings should be constant.
290 return __builtin_is_constant_evaluated();
291#else
292 while (__builtin_constant_p(*__s) && *__s)
293 __s++;
294 return __builtin_constant_p(*__s);
295#endif
296 }
297
298 /**
299 * @brief Determine whether the characters of a character array are
300 * known at compile time.
301 * @param __a The character array.
302 * @param __n Number of characters.
303 *
304 * Assumes that _CharT is a built-in character type.
305 */
306 template<typename _CharT>
307 _GLIBCXX_ALWAYS_INLINE constexpr bool
308 __constant_char_array_p(const _CharT* __a, size_t __n)
309 {
310#ifdef _GLIBCXX_HAVE_BUILTIN_IS_CONSTANT_EVALUATED
311 (void) __a;
312 (void) __n;
313 // In constexpr contexts all character arrays should be constant.
314 return __builtin_is_constant_evaluated();
315#else
316 size_t __i = 0;
317 while (__i < __n && __builtin_constant_p(__a[__i]))
318 __i++;
319 return __i == __n;
320#endif
321 }
322#endif
323
324 // 21.1
325 /**
326 * @brief Basis for explicit traits specializations.
327 *
328 * @note For any given actual character type, this definition is
329 * probably wrong. Since this is just a thin wrapper around
330 * __gnu_cxx::char_traits, it is possible to achieve a more
331 * appropriate definition by specializing __gnu_cxx::char_traits.
332 *
333 * See https://gcc.gnu.org/onlinedocs/libstdc++/manual/strings.html#strings.string.character_types
334 * for advice on how to make use of this class for @a unusual character
335 * types. Also, check out include/ext/pod_char_traits.h.
336 */
337 template<class _CharT>
338 struct char_traits : public __gnu_cxx::char_traits<_CharT>
339 { };
340
341
342 /// 21.1.3.1 char_traits specializations
343 template<>
344 struct char_traits<char>
345 {
346 typedef char char_type;
347 typedef int int_type;
348 typedef streampos pos_type;
349 typedef streamoff off_type;
350 typedef mbstate_t state_type;
351#if __cpp_lib_three_way_comparison
352 using comparison_category = strong_ordering;
353#endif
354
355 static _GLIBCXX17_CONSTEXPR void
356 assign(char_type& __c1, const char_type& __c2) _GLIBCXX_NOEXCEPT
357 { __c1 = __c2; }
358
359 static _GLIBCXX_CONSTEXPR bool
360 eq(const char_type& __c1, const char_type& __c2) _GLIBCXX_NOEXCEPT
361 { return __c1 == __c2; }
362
363 static _GLIBCXX_CONSTEXPR bool
364 lt(const char_type& __c1, const char_type& __c2) _GLIBCXX_NOEXCEPT
365 {
366 // LWG 467.
367 return (static_cast<unsigned char>(__c1)
368 < static_cast<unsigned char>(__c2));
369 }
370
371 static _GLIBCXX17_CONSTEXPR int
372 compare(const char_type* __s1, const char_type* __s2, size_t __n)
373 {
374 if (__n == 0)
375 return 0;
376#if __cplusplus >= 201703L
377 if (__builtin_constant_p(__n)
378 && __constant_char_array_p(__s1, __n)
379 && __constant_char_array_p(__s2, __n))
380 {
381 for (size_t __i = 0; __i < __n; ++__i)
382 if (lt(__s1[__i], __s2[__i]))
383 return -1;
384 else if (lt(__s2[__i], __s1[__i]))
385 return 1;
386 return 0;
387 }
388#endif
389 return __builtin_memcmp(__s1, __s2, __n);
390 }
391
392 static _GLIBCXX17_CONSTEXPR size_t
393 length(const char_type* __s)
394 {
395#if __cplusplus >= 201703L
396 if (__constant_string_p(__s))
397 return __gnu_cxx::char_traits<char_type>::length(__s);
398#endif
399 return __builtin_strlen(__s);
400 }
401
402 static _GLIBCXX17_CONSTEXPR const char_type*
403 find(const char_type* __s, size_t __n, const char_type& __a)
404 {
405 if (__n == 0)
406 return 0;
407#if __cplusplus >= 201703L
408 if (__builtin_constant_p(__n)
409 && __builtin_constant_p(__a)
410 && __constant_char_array_p(__s, __n))
411 return __gnu_cxx::char_traits<char_type>::find(__s, __n, __a);
412#endif
413 return static_cast<const char_type*>(__builtin_memchr(__s, __a, __n));
414 }
415
416 static _GLIBCXX20_CONSTEXPR char_type*
417 move(char_type* __s1, const char_type* __s2, size_t __n)
418 {
419 if (__n == 0)
420 return __s1;
421#ifdef __cpp_lib_is_constant_evaluated
422 if (std::is_constant_evaluated())
423 return __gnu_cxx::char_traits<char_type>::move(__s1, __s2, __n);
424#endif
425 return static_cast<char_type*>(__builtin_memmove(__s1, __s2, __n));
426 }
427
428 static _GLIBCXX20_CONSTEXPR char_type*
429 copy(char_type* __s1, const char_type* __s2, size_t __n)
430 {
431 if (__n == 0)
432 return __s1;
433#ifdef __cpp_lib_is_constant_evaluated
434 if (std::is_constant_evaluated())
435 return __gnu_cxx::char_traits<char_type>::copy(__s1, __s2, __n);
436#endif
437 return static_cast<char_type*>(__builtin_memcpy(__s1, __s2, __n));
438 }
439
440 static _GLIBCXX20_CONSTEXPR char_type*
441 assign(char_type* __s, size_t __n, char_type __a)
442 {
443 if (__n == 0)
444 return __s;
445#ifdef __cpp_lib_is_constant_evaluated
446 if (std::is_constant_evaluated())
447 return __gnu_cxx::char_traits<char_type>::assign(__s, __n, __a);
448#endif
449 return static_cast<char_type*>(__builtin_memset(__s, __a, __n));
450 }
451
452 static _GLIBCXX_CONSTEXPR char_type
453 to_char_type(const int_type& __c) _GLIBCXX_NOEXCEPT
454 { return static_cast<char_type>(__c); }
455
456 // To keep both the byte 0xff and the eof symbol 0xffffffff
457 // from ending up as 0xffffffff.
458 static _GLIBCXX_CONSTEXPR int_type
459 to_int_type(const char_type& __c) _GLIBCXX_NOEXCEPT
460 { return static_cast<int_type>(static_cast<unsigned char>(__c)); }
461
462 static _GLIBCXX_CONSTEXPR bool
463 eq_int_type(const int_type& __c1, const int_type& __c2) _GLIBCXX_NOEXCEPT
464 { return __c1 == __c2; }
465
466 static _GLIBCXX_CONSTEXPR int_type
467 eof() _GLIBCXX_NOEXCEPT
468 { return static_cast<int_type>(_GLIBCXX_STDIO_EOF); }
469
470 static _GLIBCXX_CONSTEXPR int_type
471 not_eof(const int_type& __c) _GLIBCXX_NOEXCEPT
472 { return (__c == eof()) ? 0 : __c; }
473 };
474
475
476#ifdef _GLIBCXX_USE_WCHAR_T
477 /// 21.1.3.2 char_traits specializations
478 template<>
479 struct char_traits<wchar_t>
480 {
481 typedef wchar_t char_type;
482 typedef wint_t int_type;
483 typedef streamoff off_type;
484 typedef wstreampos pos_type;
485 typedef mbstate_t state_type;
486#if __cpp_lib_three_way_comparison
487 using comparison_category = strong_ordering;
488#endif
489
490 static _GLIBCXX17_CONSTEXPR void
491 assign(char_type& __c1, const char_type& __c2) _GLIBCXX_NOEXCEPT
492 { __c1 = __c2; }
493
494 static _GLIBCXX_CONSTEXPR bool
495 eq(const char_type& __c1, const char_type& __c2) _GLIBCXX_NOEXCEPT
496 { return __c1 == __c2; }
497
498 static _GLIBCXX_CONSTEXPR bool
499 lt(const char_type& __c1, const char_type& __c2) _GLIBCXX_NOEXCEPT
500 { return __c1 < __c2; }
501
502 static _GLIBCXX17_CONSTEXPR int
503 compare(const char_type* __s1, const char_type* __s2, size_t __n)
504 {
505 if (__n == 0)
506 return 0;
507#if __cplusplus >= 201703L
508 if (__builtin_constant_p(__n)
509 && __constant_char_array_p(__s1, __n)
510 && __constant_char_array_p(__s2, __n))
511 return __gnu_cxx::char_traits<char_type>::compare(__s1, __s2, __n);
512#endif
513 return wmemcmp(__s1, __s2, __n);
514 }
515
516 static _GLIBCXX17_CONSTEXPR size_t
517 length(const char_type* __s)
518 {
519#if __cplusplus >= 201703L
520 if (__constant_string_p(__s))
521 return __gnu_cxx::char_traits<char_type>::length(__s);
522#endif
523 return wcslen(__s);
524 }
525
526 static _GLIBCXX17_CONSTEXPR const char_type*
527 find(const char_type* __s, size_t __n, const char_type& __a)
528 {
529 if (__n == 0)
530 return 0;
531#if __cplusplus >= 201703L
532 if (__builtin_constant_p(__n)
533 && __builtin_constant_p(__a)
534 && __constant_char_array_p(__s, __n))
535 return __gnu_cxx::char_traits<char_type>::find(__s, __n, __a);
536#endif
537 return wmemchr(__s, c: __a, __n);
538 }
539
540 static _GLIBCXX20_CONSTEXPR char_type*
541 move(char_type* __s1, const char_type* __s2, size_t __n)
542 {
543 if (__n == 0)
544 return __s1;
545#ifdef __cpp_lib_is_constant_evaluated
546 if (std::is_constant_evaluated())
547 return __gnu_cxx::char_traits<char_type>::move(__s1, __s2, __n);
548#endif
549 return wmemmove(__s1, __s2, __n);
550 }
551
552 static _GLIBCXX20_CONSTEXPR char_type*
553 copy(char_type* __s1, const char_type* __s2, size_t __n)
554 {
555 if (__n == 0)
556 return __s1;
557#ifdef __cpp_lib_is_constant_evaluated
558 if (std::is_constant_evaluated())
559 return __gnu_cxx::char_traits<char_type>::copy(__s1, __s2, __n);
560#endif
561 return wmemcpy(__s1, __s2, __n);
562 }
563
564 static _GLIBCXX20_CONSTEXPR char_type*
565 assign(char_type* __s, size_t __n, char_type __a)
566 {
567 if (__n == 0)
568 return __s;
569#ifdef __cpp_lib_is_constant_evaluated
570 if (std::is_constant_evaluated())
571 return __gnu_cxx::char_traits<char_type>::assign(__s, __n, __a);
572#endif
573 return wmemset(__s, c: __a, __n);
574 }
575
576 static _GLIBCXX_CONSTEXPR char_type
577 to_char_type(const int_type& __c) _GLIBCXX_NOEXCEPT
578 { return char_type(__c); }
579
580 static _GLIBCXX_CONSTEXPR int_type
581 to_int_type(const char_type& __c) _GLIBCXX_NOEXCEPT
582 { return int_type(__c); }
583
584 static _GLIBCXX_CONSTEXPR bool
585 eq_int_type(const int_type& __c1, const int_type& __c2) _GLIBCXX_NOEXCEPT
586 { return __c1 == __c2; }
587
588 static _GLIBCXX_CONSTEXPR int_type
589 eof() _GLIBCXX_NOEXCEPT
590 { return static_cast<int_type>(WEOF); }
591
592 static _GLIBCXX_CONSTEXPR int_type
593 not_eof(const int_type& __c) _GLIBCXX_NOEXCEPT
594 { return eq_int_type(c1: __c, c2: eof()) ? 0 : __c; }
595 };
596#endif //_GLIBCXX_USE_WCHAR_T
597
598#ifdef _GLIBCXX_USE_CHAR8_T
599 template<>
600 struct char_traits<char8_t>
601 {
602 typedef char8_t char_type;
603 typedef unsigned int int_type;
604 typedef u8streampos pos_type;
605 typedef streamoff off_type;
606 typedef mbstate_t state_type;
607#if __cpp_lib_three_way_comparison
608 using comparison_category = strong_ordering;
609#endif
610
611 static _GLIBCXX17_CONSTEXPR void
612 assign(char_type& __c1, const char_type& __c2) _GLIBCXX_NOEXCEPT
613 { __c1 = __c2; }
614
615 static _GLIBCXX_CONSTEXPR bool
616 eq(const char_type& __c1, const char_type& __c2) _GLIBCXX_NOEXCEPT
617 { return __c1 == __c2; }
618
619 static _GLIBCXX_CONSTEXPR bool
620 lt(const char_type& __c1, const char_type& __c2) _GLIBCXX_NOEXCEPT
621 { return __c1 < __c2; }
622
623 static _GLIBCXX17_CONSTEXPR int
624 compare(const char_type* __s1, const char_type* __s2, size_t __n)
625 {
626 if (__n == 0)
627 return 0;
628#if __cplusplus > 201402
629 if (__builtin_constant_p(__n)
630 && __constant_char_array_p(__s1, __n)
631 && __constant_char_array_p(__s2, __n))
632 return __gnu_cxx::char_traits<char_type>::compare(__s1, __s2, __n);
633#endif
634 return __builtin_memcmp(__s1, __s2, __n);
635 }
636
637 static _GLIBCXX17_CONSTEXPR size_t
638 length(const char_type* __s)
639 {
640#if __cplusplus > 201402
641 if (__constant_string_p(__s))
642 return __gnu_cxx::char_traits<char_type>::length(__s);
643#endif
644 size_t __i = 0;
645 while (!eq(__s[__i], char_type()))
646 ++__i;
647 return __i;
648 }
649
650 static _GLIBCXX17_CONSTEXPR const char_type*
651 find(const char_type* __s, size_t __n, const char_type& __a)
652 {
653 if (__n == 0)
654 return 0;
655#if __cplusplus > 201402
656 if (__builtin_constant_p(__n)
657 && __builtin_constant_p(__a)
658 && __constant_char_array_p(__s, __n))
659 return __gnu_cxx::char_traits<char_type>::find(__s, __n, __a);
660#endif
661 return static_cast<const char_type*>(__builtin_memchr(__s, __a, __n));
662 }
663
664 static _GLIBCXX20_CONSTEXPR char_type*
665 move(char_type* __s1, const char_type* __s2, size_t __n)
666 {
667 if (__n == 0)
668 return __s1;
669#ifdef __cpp_lib_is_constant_evaluated
670 if (std::is_constant_evaluated())
671 return __gnu_cxx::char_traits<char_type>::move(__s1, __s2, __n);
672#endif
673 return static_cast<char_type*>(__builtin_memmove(__s1, __s2, __n));
674 }
675
676 static _GLIBCXX20_CONSTEXPR char_type*
677 copy(char_type* __s1, const char_type* __s2, size_t __n)
678 {
679 if (__n == 0)
680 return __s1;
681#ifdef __cpp_lib_is_constant_evaluated
682 if (std::is_constant_evaluated())
683 return __gnu_cxx::char_traits<char_type>::copy(__s1, __s2, __n);
684#endif
685 return static_cast<char_type*>(__builtin_memcpy(__s1, __s2, __n));
686 }
687
688 static _GLIBCXX20_CONSTEXPR char_type*
689 assign(char_type* __s, size_t __n, char_type __a)
690 {
691 if (__n == 0)
692 return __s;
693#ifdef __cpp_lib_is_constant_evaluated
694 if (std::is_constant_evaluated())
695 return __gnu_cxx::char_traits<char_type>::assign(__s, __n, __a);
696#endif
697 return static_cast<char_type*>(__builtin_memset(__s, __a, __n));
698 }
699
700 static _GLIBCXX_CONSTEXPR char_type
701 to_char_type(const int_type& __c) _GLIBCXX_NOEXCEPT
702 { return char_type(__c); }
703
704 static _GLIBCXX_CONSTEXPR int_type
705 to_int_type(const char_type& __c) _GLIBCXX_NOEXCEPT
706 { return int_type(__c); }
707
708 static _GLIBCXX_CONSTEXPR bool
709 eq_int_type(const int_type& __c1, const int_type& __c2) _GLIBCXX_NOEXCEPT
710 { return __c1 == __c2; }
711
712 static _GLIBCXX_CONSTEXPR int_type
713 eof() _GLIBCXX_NOEXCEPT
714 { return static_cast<int_type>(-1); }
715
716 static _GLIBCXX_CONSTEXPR int_type
717 not_eof(const int_type& __c) _GLIBCXX_NOEXCEPT
718 { return eq_int_type(__c, eof()) ? 0 : __c; }
719 };
720#endif //_GLIBCXX_USE_CHAR8_T
721
722_GLIBCXX_END_NAMESPACE_VERSION
723} // namespace
724
725#if __cplusplus >= 201103L
726
727#include <cstdint>
728
729namespace std _GLIBCXX_VISIBILITY(default)
730{
731_GLIBCXX_BEGIN_NAMESPACE_VERSION
732
733 template<>
734 struct char_traits<char16_t>
735 {
736 typedef char16_t char_type;
737#ifdef _GLIBCXX_USE_C99_STDINT_TR1
738 typedef uint_least16_t int_type;
739#elif defined __UINT_LEAST16_TYPE__
740 typedef __UINT_LEAST16_TYPE__ int_type;
741#else
742 typedef make_unsigned<char16_t>::type int_type;
743#endif
744 typedef streamoff off_type;
745 typedef u16streampos pos_type;
746 typedef mbstate_t state_type;
747#if __cpp_lib_three_way_comparison
748 using comparison_category = strong_ordering;
749#endif
750
751 static _GLIBCXX17_CONSTEXPR void
752 assign(char_type& __c1, const char_type& __c2) noexcept
753 { __c1 = __c2; }
754
755 static constexpr bool
756 eq(const char_type& __c1, const char_type& __c2) noexcept
757 { return __c1 == __c2; }
758
759 static constexpr bool
760 lt(const char_type& __c1, const char_type& __c2) noexcept
761 { return __c1 < __c2; }
762
763 static _GLIBCXX17_CONSTEXPR int
764 compare(const char_type* __s1, const char_type* __s2, size_t __n)
765 {
766 for (size_t __i = 0; __i < __n; ++__i)
767 if (lt(c1: __s1[__i], c2: __s2[__i]))
768 return -1;
769 else if (lt(c1: __s2[__i], c2: __s1[__i]))
770 return 1;
771 return 0;
772 }
773
774 static _GLIBCXX17_CONSTEXPR size_t
775 length(const char_type* __s)
776 {
777 size_t __i = 0;
778 while (!eq(c1: __s[__i], c2: char_type()))
779 ++__i;
780 return __i;
781 }
782
783 static _GLIBCXX17_CONSTEXPR const char_type*
784 find(const char_type* __s, size_t __n, const char_type& __a)
785 {
786 for (size_t __i = 0; __i < __n; ++__i)
787 if (eq(c1: __s[__i], c2: __a))
788 return __s + __i;
789 return 0;
790 }
791
792 static _GLIBCXX20_CONSTEXPR char_type*
793 move(char_type* __s1, const char_type* __s2, size_t __n)
794 {
795 if (__n == 0)
796 return __s1;
797#ifdef __cpp_lib_is_constant_evaluated
798 if (std::is_constant_evaluated())
799 return __gnu_cxx::char_traits<char_type>::move(__s1, __s2, __n);
800#endif
801 return (static_cast<char_type*>
802 (__builtin_memmove(__s1, __s2, __n * sizeof(char_type))));
803 }
804
805 static _GLIBCXX20_CONSTEXPR char_type*
806 copy(char_type* __s1, const char_type* __s2, size_t __n)
807 {
808 if (__n == 0)
809 return __s1;
810#ifdef __cpp_lib_is_constant_evaluated
811 if (std::is_constant_evaluated())
812 return __gnu_cxx::char_traits<char_type>::copy(__s1, __s2, __n);
813#endif
814 return (static_cast<char_type*>
815 (__builtin_memcpy(__s1, __s2, __n * sizeof(char_type))));
816 }
817
818 static _GLIBCXX20_CONSTEXPR char_type*
819 assign(char_type* __s, size_t __n, char_type __a)
820 {
821 for (size_t __i = 0; __i < __n; ++__i)
822 assign(c1&: __s[__i], c2: __a);
823 return __s;
824 }
825
826 static constexpr char_type
827 to_char_type(const int_type& __c) noexcept
828 { return char_type(__c); }
829
830 static constexpr int_type
831 to_int_type(const char_type& __c) noexcept
832 { return __c == eof() ? int_type(0xfffd) : int_type(__c); }
833
834 static constexpr bool
835 eq_int_type(const int_type& __c1, const int_type& __c2) noexcept
836 { return __c1 == __c2; }
837
838 static constexpr int_type
839 eof() noexcept
840 { return static_cast<int_type>(-1); }
841
842 static constexpr int_type
843 not_eof(const int_type& __c) noexcept
844 { return eq_int_type(c1: __c, c2: eof()) ? 0 : __c; }
845 };
846
847 template<>
848 struct char_traits<char32_t>
849 {
850 typedef char32_t char_type;
851#ifdef _GLIBCXX_USE_C99_STDINT_TR1
852 typedef uint_least32_t int_type;
853#elif defined __UINT_LEAST32_TYPE__
854 typedef __UINT_LEAST32_TYPE__ int_type;
855#else
856 typedef make_unsigned<char32_t>::type int_type;
857#endif
858 typedef streamoff off_type;
859 typedef u32streampos pos_type;
860 typedef mbstate_t state_type;
861#if __cpp_lib_three_way_comparison
862 using comparison_category = strong_ordering;
863#endif
864
865 static _GLIBCXX17_CONSTEXPR void
866 assign(char_type& __c1, const char_type& __c2) noexcept
867 { __c1 = __c2; }
868
869 static constexpr bool
870 eq(const char_type& __c1, const char_type& __c2) noexcept
871 { return __c1 == __c2; }
872
873 static constexpr bool
874 lt(const char_type& __c1, const char_type& __c2) noexcept
875 { return __c1 < __c2; }
876
877 static _GLIBCXX17_CONSTEXPR int
878 compare(const char_type* __s1, const char_type* __s2, size_t __n)
879 {
880 for (size_t __i = 0; __i < __n; ++__i)
881 if (lt(c1: __s1[__i], c2: __s2[__i]))
882 return -1;
883 else if (lt(c1: __s2[__i], c2: __s1[__i]))
884 return 1;
885 return 0;
886 }
887
888 static _GLIBCXX17_CONSTEXPR size_t
889 length(const char_type* __s)
890 {
891 size_t __i = 0;
892 while (!eq(c1: __s[__i], c2: char_type()))
893 ++__i;
894 return __i;
895 }
896
897 static _GLIBCXX17_CONSTEXPR const char_type*
898 find(const char_type* __s, size_t __n, const char_type& __a)
899 {
900 for (size_t __i = 0; __i < __n; ++__i)
901 if (eq(c1: __s[__i], c2: __a))
902 return __s + __i;
903 return 0;
904 }
905
906 static _GLIBCXX20_CONSTEXPR char_type*
907 move(char_type* __s1, const char_type* __s2, size_t __n)
908 {
909 if (__n == 0)
910 return __s1;
911#ifdef __cpp_lib_is_constant_evaluated
912 if (std::is_constant_evaluated())
913 return __gnu_cxx::char_traits<char_type>::move(__s1, __s2, __n);
914#endif
915 return (static_cast<char_type*>
916 (__builtin_memmove(__s1, __s2, __n * sizeof(char_type))));
917 }
918
919 static _GLIBCXX20_CONSTEXPR char_type*
920 copy(char_type* __s1, const char_type* __s2, size_t __n)
921 {
922 if (__n == 0)
923 return __s1;
924#ifdef __cpp_lib_is_constant_evaluated
925 if (std::is_constant_evaluated())
926 return __gnu_cxx::char_traits<char_type>::copy(__s1, __s2, __n);
927#endif
928 return (static_cast<char_type*>
929 (__builtin_memcpy(__s1, __s2, __n * sizeof(char_type))));
930 }
931
932 static _GLIBCXX20_CONSTEXPR char_type*
933 assign(char_type* __s, size_t __n, char_type __a)
934 {
935 for (size_t __i = 0; __i < __n; ++__i)
936 assign(c1&: __s[__i], c2: __a);
937 return __s;
938 }
939
940 static constexpr char_type
941 to_char_type(const int_type& __c) noexcept
942 { return char_type(__c); }
943
944 static constexpr int_type
945 to_int_type(const char_type& __c) noexcept
946 { return int_type(__c); }
947
948 static constexpr bool
949 eq_int_type(const int_type& __c1, const int_type& __c2) noexcept
950 { return __c1 == __c2; }
951
952 static constexpr int_type
953 eof() noexcept
954 { return static_cast<int_type>(-1); }
955
956 static constexpr int_type
957 not_eof(const int_type& __c) noexcept
958 { return eq_int_type(c1: __c, c2: eof()) ? 0 : __c; }
959 };
960
961#if __cpp_lib_three_way_comparison
962 namespace __detail
963 {
964 template<typename _ChTraits>
965 constexpr auto
966 __char_traits_cmp_cat(int __cmp) noexcept
967 {
968 if constexpr (requires { typename _ChTraits::comparison_category; })
969 {
970 using _Cat = typename _ChTraits::comparison_category;
971 static_assert( !is_void_v<common_comparison_category_t<_Cat>> );
972 return static_cast<_Cat>(__cmp <=> 0);
973 }
974 else
975 return static_cast<weak_ordering>(__cmp <=> 0);
976 }
977 } // namespace __detail
978#endif // C++20
979
980_GLIBCXX_END_NAMESPACE_VERSION
981} // namespace
982
983#endif // C++11
984
985#endif // _CHAR_TRAITS_H
986

source code of include/c++/11/bits/char_traits.h