libstdc++
type_traits
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1// C++11 <type_traits> -*- C++ -*-
2
3// Copyright (C) 2007-2021 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 include/type_traits
26 * This is a Standard C++ Library header.
27 */
28
29#ifndef _GLIBCXX_TYPE_TRAITS
30#define _GLIBCXX_TYPE_TRAITS 1
31
32#pragma GCC system_header
33
34#if __cplusplus < 201103L
35# include <bits/c++0x_warning.h>
36#else
37
38#include <bits/c++config.h>
39
40namespace std _GLIBCXX_VISIBILITY(default)
41{
42_GLIBCXX_BEGIN_NAMESPACE_VERSION
43
44 template<typename... _Elements>
45 class tuple;
46
47 template<typename _Tp>
48 class reference_wrapper;
49
50 /**
51 * @defgroup metaprogramming Metaprogramming
52 * @ingroup utilities
53 *
54 * Template utilities for compile-time introspection and modification,
55 * including type classification traits, type property inspection traits
56 * and type transformation traits.
57 *
58 * @since C++11
59 *
60 * @{
61 */
62
63 /// integral_constant
64 template<typename _Tp, _Tp __v>
65 struct integral_constant
66 {
67 static constexpr _Tp value = __v;
68 typedef _Tp value_type;
69 typedef integral_constant<_Tp, __v> type;
70 constexpr operator value_type() const noexcept { return value; }
71#if __cplusplus > 201103L
72
73#define __cpp_lib_integral_constant_callable 201304
74
75 constexpr value_type operator()() const noexcept { return value; }
76#endif
77 };
78
79 template<typename _Tp, _Tp __v>
80 constexpr _Tp integral_constant<_Tp, __v>::value;
81
82 /// The type used as a compile-time boolean with true value.
83 using true_type = integral_constant<bool, true>;
84
85 /// The type used as a compile-time boolean with false value.
86 using false_type = integral_constant<bool, false>;
87
88 /// @cond undocumented
89 /// bool_constant for C++11
90 template<bool __v>
91 using __bool_constant = integral_constant<bool, __v>;
92 /// @endcond
93
94#if __cplusplus >= 201703L
95# define __cpp_lib_bool_constant 201505
96 /// Alias template for compile-time boolean constant types.
97 /// @since C++17
98 template<bool __v>
99 using bool_constant = integral_constant<bool, __v>;
100#endif
101
102 // Metaprogramming helper types.
103
104 template<bool, typename, typename>
105 struct conditional;
106
107 /// @cond undocumented
108 template <typename _Type>
109 struct __type_identity
110 { using type = _Type; };
111
112 template<typename _Tp>
113 using __type_identity_t = typename __type_identity<_Tp>::type;
114
115 template<typename...>
116 struct __or_;
117
118 template<>
119 struct __or_<>
120 : public false_type
121 { };
122
123 template<typename _B1>
124 struct __or_<_B1>
125 : public _B1
126 { };
127
128 template<typename _B1, typename _B2>
129 struct __or_<_B1, _B2>
130 : public conditional<_B1::value, _B1, _B2>::type
131 { };
132
133 template<typename _B1, typename _B2, typename _B3, typename... _Bn>
134 struct __or_<_B1, _B2, _B3, _Bn...>
135 : public conditional<_B1::value, _B1, __or_<_B2, _B3, _Bn...>>::type
136 { };
137
138 template<typename...>
139 struct __and_;
140
141 template<>
142 struct __and_<>
143 : public true_type
144 { };
145
146 template<typename _B1>
147 struct __and_<_B1>
148 : public _B1
149 { };
150
151 template<typename _B1, typename _B2>
152 struct __and_<_B1, _B2>
153 : public conditional<_B1::value, _B2, _B1>::type
154 { };
155
156 template<typename _B1, typename _B2, typename _B3, typename... _Bn>
157 struct __and_<_B1, _B2, _B3, _Bn...>
158 : public conditional<_B1::value, __and_<_B2, _B3, _Bn...>, _B1>::type
159 { };
160
161 template<typename _Pp>
162 struct __not_
163 : public __bool_constant<!bool(_Pp::value)>
164 { };
165 /// @endcond
166
167#if __cplusplus >= 201703L
168
169 /// @cond undocumented
170 template<typename... _Bn>
171 inline constexpr bool __or_v = __or_<_Bn...>::value;
172 template<typename... _Bn>
173 inline constexpr bool __and_v = __and_<_Bn...>::value;
174 /// @endcond
175
176#define __cpp_lib_logical_traits 201510
177
178 template<typename... _Bn>
179 struct conjunction
180 : __and_<_Bn...>
181 { };
182
183 template<typename... _Bn>
184 struct disjunction
185 : __or_<_Bn...>
186 { };
187
188 template<typename _Pp>
189 struct negation
190 : __not_<_Pp>
191 { };
192
193 /** @ingroup variable_templates
194 * @{
195 */
196 template<typename... _Bn>
197 inline constexpr bool conjunction_v = conjunction<_Bn...>::value;
198
199 template<typename... _Bn>
200 inline constexpr bool disjunction_v = disjunction<_Bn...>::value;
201
202 template<typename _Pp>
203 inline constexpr bool negation_v = negation<_Pp>::value;
204 /// @}
205
206#endif // C++17
207
208 // Forward declarations
209 template<typename>
210 struct is_reference;
211 template<typename>
212 struct is_function;
213 template<typename>
214 struct is_void;
215 template<typename>
216 struct remove_cv;
217 template<typename>
218 struct is_const;
219
220 /// @cond undocumented
221 template<typename>
222 struct __is_array_unknown_bounds;
223
224 // Helper functions that return false_type for incomplete classes,
225 // incomplete unions and arrays of known bound from those.
226
227 template <typename _Tp, size_t = sizeof(_Tp)>
228 constexpr true_type __is_complete_or_unbounded(__type_identity<_Tp>)
229 { return {}; }
230
231 template <typename _TypeIdentity,
232 typename _NestedType = typename _TypeIdentity::type>
233 constexpr typename __or_<
234 is_reference<_NestedType>,
235 is_function<_NestedType>,
236 is_void<_NestedType>,
237 __is_array_unknown_bounds<_NestedType>
238 >::type __is_complete_or_unbounded(_TypeIdentity)
239 { return {}; }
240
241 // For several sfinae-friendly trait implementations we transport both the
242 // result information (as the member type) and the failure information (no
243 // member type). This is very similar to std::enable_if, but we cannot use
244 // them, because we need to derive from them as an implementation detail.
245
246 template<typename _Tp>
247 struct __success_type
248 { typedef _Tp type; };
249
250 struct __failure_type
251 { };
252
253 // __remove_cv_t (std::remove_cv_t for C++11).
254 template<typename _Tp>
255 using __remove_cv_t = typename remove_cv<_Tp>::type;
256
257 // Primary type categories.
258
259 template<typename>
260 struct __is_void_helper
261 : public false_type { };
262
263 template<>
264 struct __is_void_helper<void>
265 : public true_type { };
266 /// @endcond
267
268 /// is_void
269 template<typename _Tp>
270 struct is_void
271 : public __is_void_helper<__remove_cv_t<_Tp>>::type
272 { };
273
274 /// @cond undocumented
275 template<typename>
276 struct __is_integral_helper
277 : public false_type { };
278
279 template<>
280 struct __is_integral_helper<bool>
281 : public true_type { };
282
283 template<>
284 struct __is_integral_helper<char>
285 : public true_type { };
286
287 template<>
288 struct __is_integral_helper<signed char>
289 : public true_type { };
290
291 template<>
292 struct __is_integral_helper<unsigned char>
293 : public true_type { };
294
295 // We want is_integral<wchar_t> to be true (and make_signed/unsigned to work)
296 // even when libc doesn't provide working <wchar.h> and related functions,
297 // so check __WCHAR_TYPE__ instead of _GLIBCXX_USE_WCHAR_T.
298#ifdef __WCHAR_TYPE__
299 template<>
300 struct __is_integral_helper<wchar_t>
301 : public true_type { };
302#endif
303
304#ifdef _GLIBCXX_USE_CHAR8_T
305 template<>
306 struct __is_integral_helper<char8_t>
307 : public true_type { };
308#endif
309
310 template<>
311 struct __is_integral_helper<char16_t>
312 : public true_type { };
313
314 template<>
315 struct __is_integral_helper<char32_t>
316 : public true_type { };
317
318 template<>
319 struct __is_integral_helper<short>
320 : public true_type { };
321
322 template<>
323 struct __is_integral_helper<unsigned short>
324 : public true_type { };
325
326 template<>
327 struct __is_integral_helper<int>
328 : public true_type { };
329
330 template<>
331 struct __is_integral_helper<unsigned int>
332 : public true_type { };
333
334 template<>
335 struct __is_integral_helper<long>
336 : public true_type { };
337
338 template<>
339 struct __is_integral_helper<unsigned long>
340 : public true_type { };
341
342 template<>
343 struct __is_integral_helper<long long>
344 : public true_type { };
345
346 template<>
347 struct __is_integral_helper<unsigned long long>
348 : public true_type { };
349
350 // Conditionalizing on __STRICT_ANSI__ here will break any port that
351 // uses one of these types for size_t.
352#if defined(__GLIBCXX_TYPE_INT_N_0)
353 template<>
354 struct __is_integral_helper<__GLIBCXX_TYPE_INT_N_0>
355 : public true_type { };
356
357 template<>
358 struct __is_integral_helper<unsigned __GLIBCXX_TYPE_INT_N_0>
359 : public true_type { };
360#endif
361#if defined(__GLIBCXX_TYPE_INT_N_1)
362 template<>
363 struct __is_integral_helper<__GLIBCXX_TYPE_INT_N_1>
364 : public true_type { };
365
366 template<>
367 struct __is_integral_helper<unsigned __GLIBCXX_TYPE_INT_N_1>
368 : public true_type { };
369#endif
370#if defined(__GLIBCXX_TYPE_INT_N_2)
371 template<>
372 struct __is_integral_helper<__GLIBCXX_TYPE_INT_N_2>
373 : public true_type { };
374
375 template<>
376 struct __is_integral_helper<unsigned __GLIBCXX_TYPE_INT_N_2>
377 : public true_type { };
378#endif
379#if defined(__GLIBCXX_TYPE_INT_N_3)
380 template<>
381 struct __is_integral_helper<__GLIBCXX_TYPE_INT_N_3>
382 : public true_type { };
383
384 template<>
385 struct __is_integral_helper<unsigned __GLIBCXX_TYPE_INT_N_3>
386 : public true_type { };
387#endif
388 /// @endcond
389
390 /// is_integral
391 template<typename _Tp>
392 struct is_integral
393 : public __is_integral_helper<__remove_cv_t<_Tp>>::type
394 { };
395
396 /// @cond undocumented
397 template<typename>
398 struct __is_floating_point_helper
399 : public false_type { };
400
401 template<>
402 struct __is_floating_point_helper<float>
403 : public true_type { };
404
405 template<>
406 struct __is_floating_point_helper<double>
407 : public true_type { };
408
409 template<>
410 struct __is_floating_point_helper<long double>
411 : public true_type { };
412
413#if !defined(__STRICT_ANSI__) && defined(_GLIBCXX_USE_FLOAT128)
414 template<>
415 struct __is_floating_point_helper<__float128>
416 : public true_type { };
417#endif
418 /// @endcond
419
420 /// is_floating_point
421 template<typename _Tp>
422 struct is_floating_point
423 : public __is_floating_point_helper<__remove_cv_t<_Tp>>::type
424 { };
425
426 /// is_array
427 template<typename>
428 struct is_array
429 : public false_type { };
430
431 template<typename _Tp, std::size_t _Size>
432 struct is_array<_Tp[_Size]>
433 : public true_type { };
434
435 template<typename _Tp>
436 struct is_array<_Tp[]>
437 : public true_type { };
438
439 template<typename>
440 struct __is_pointer_helper
441 : public false_type { };
442
443 template<typename _Tp>
444 struct __is_pointer_helper<_Tp*>
445 : public true_type { };
446
447 /// is_pointer
448 template<typename _Tp>
449 struct is_pointer
450 : public __is_pointer_helper<__remove_cv_t<_Tp>>::type
451 { };
452
453 /// is_lvalue_reference
454 template<typename>
455 struct is_lvalue_reference
456 : public false_type { };
457
458 template<typename _Tp>
459 struct is_lvalue_reference<_Tp&>
460 : public true_type { };
461
462 /// is_rvalue_reference
463 template<typename>
464 struct is_rvalue_reference
465 : public false_type { };
466
467 template<typename _Tp>
468 struct is_rvalue_reference<_Tp&&>
469 : public true_type { };
470
471 template<typename>
472 struct __is_member_object_pointer_helper
473 : public false_type { };
474
475 template<typename _Tp, typename _Cp>
476 struct __is_member_object_pointer_helper<_Tp _Cp::*>
477 : public __not_<is_function<_Tp>>::type { };
478
479 /// is_member_object_pointer
480 template<typename _Tp>
481 struct is_member_object_pointer
482 : public __is_member_object_pointer_helper<__remove_cv_t<_Tp>>::type
483 { };
484
485 template<typename>
486 struct __is_member_function_pointer_helper
487 : public false_type { };
488
489 template<typename _Tp, typename _Cp>
490 struct __is_member_function_pointer_helper<_Tp _Cp::*>
491 : public is_function<_Tp>::type { };
492
493 /// is_member_function_pointer
494 template<typename _Tp>
495 struct is_member_function_pointer
496 : public __is_member_function_pointer_helper<__remove_cv_t<_Tp>>::type
497 { };
498
499 /// is_enum
500 template<typename _Tp>
501 struct is_enum
502 : public integral_constant<bool, __is_enum(_Tp)>
503 { };
504
505 /// is_union
506 template<typename _Tp>
507 struct is_union
508 : public integral_constant<bool, __is_union(_Tp)>
509 { };
510
511 /// is_class
512 template<typename _Tp>
513 struct is_class
514 : public integral_constant<bool, __is_class(_Tp)>
515 { };
516
517 /// is_function
518 template<typename _Tp>
519 struct is_function
520 : public __bool_constant<!is_const<const _Tp>::value> { };
521
522 template<typename _Tp>
523 struct is_function<_Tp&>
524 : public false_type { };
525
526 template<typename _Tp>
527 struct is_function<_Tp&&>
528 : public false_type { };
529
530#define __cpp_lib_is_null_pointer 201309
531
532 template<typename>
533 struct __is_null_pointer_helper
534 : public false_type { };
535
536 template<>
537 struct __is_null_pointer_helper<std::nullptr_t>
538 : public true_type { };
539
540 /// is_null_pointer (LWG 2247).
541 template<typename _Tp>
542 struct is_null_pointer
543 : public __is_null_pointer_helper<__remove_cv_t<_Tp>>::type
544 { };
545
546 /// __is_nullptr_t (deprecated extension).
547 /// @deprecated Use `is_null_pointer` instead.
548 template<typename _Tp>
549 struct __is_nullptr_t
550 : public is_null_pointer<_Tp>
551 { } _GLIBCXX_DEPRECATED_SUGGEST("std::is_null_pointer");
552
553 // Composite type categories.
554
555 /// is_reference
556 template<typename _Tp>
557 struct is_reference
558 : public __or_<is_lvalue_reference<_Tp>,
559 is_rvalue_reference<_Tp>>::type
560 { };
561
562 /// is_arithmetic
563 template<typename _Tp>
564 struct is_arithmetic
565 : public __or_<is_integral<_Tp>, is_floating_point<_Tp>>::type
566 { };
567
568 /// is_fundamental
569 template<typename _Tp>
570 struct is_fundamental
571 : public __or_<is_arithmetic<_Tp>, is_void<_Tp>,
572 is_null_pointer<_Tp>>::type
573 { };
574
575 /// is_object
576 template<typename _Tp>
577 struct is_object
578 : public __not_<__or_<is_function<_Tp>, is_reference<_Tp>,
579 is_void<_Tp>>>::type
580 { };
581
582 template<typename>
583 struct is_member_pointer;
584
585 /// is_scalar
586 template<typename _Tp>
587 struct is_scalar
588 : public __or_<is_arithmetic<_Tp>, is_enum<_Tp>, is_pointer<_Tp>,
589 is_member_pointer<_Tp>, is_null_pointer<_Tp>>::type
590 { };
591
592 /// is_compound
593 template<typename _Tp>
594 struct is_compound
595 : public __not_<is_fundamental<_Tp>>::type { };
596
597 /// @cond undocumented
598 template<typename _Tp>
599 struct __is_member_pointer_helper
600 : public false_type { };
601
602 template<typename _Tp, typename _Cp>
603 struct __is_member_pointer_helper<_Tp _Cp::*>
604 : public true_type { };
605 /// @endcond
606
607 /// is_member_pointer
608 template<typename _Tp>
609 struct is_member_pointer
610 : public __is_member_pointer_helper<__remove_cv_t<_Tp>>::type
611 { };
612
613 template<typename, typename>
614 struct is_same;
615
616 /// @cond undocumented
617 template<typename _Tp, typename... _Types>
618 using __is_one_of = __or_<is_same<_Tp, _Types>...>;
619
620 // Check if a type is one of the signed integer types.
621 template<typename _Tp>
622 using __is_signed_integer = __is_one_of<__remove_cv_t<_Tp>,
623 signed char, signed short, signed int, signed long,
624 signed long long
625#if defined(__GLIBCXX_TYPE_INT_N_0)
626 , signed __GLIBCXX_TYPE_INT_N_0
627#endif
628#if defined(__GLIBCXX_TYPE_INT_N_1)
629 , signed __GLIBCXX_TYPE_INT_N_1
630#endif
631#if defined(__GLIBCXX_TYPE_INT_N_2)
632 , signed __GLIBCXX_TYPE_INT_N_2
633#endif
634#if defined(__GLIBCXX_TYPE_INT_N_3)
635 , signed __GLIBCXX_TYPE_INT_N_3
636#endif
637 >;
638
639 // Check if a type is one of the unsigned integer types.
640 template<typename _Tp>
641 using __is_unsigned_integer = __is_one_of<__remove_cv_t<_Tp>,
642 unsigned char, unsigned short, unsigned int, unsigned long,
643 unsigned long long
644#if defined(__GLIBCXX_TYPE_INT_N_0)
645 , unsigned __GLIBCXX_TYPE_INT_N_0
646#endif
647#if defined(__GLIBCXX_TYPE_INT_N_1)
648 , unsigned __GLIBCXX_TYPE_INT_N_1
649#endif
650#if defined(__GLIBCXX_TYPE_INT_N_2)
651 , unsigned __GLIBCXX_TYPE_INT_N_2
652#endif
653#if defined(__GLIBCXX_TYPE_INT_N_3)
654 , unsigned __GLIBCXX_TYPE_INT_N_3
655#endif
656 >;
657
658 // Check if a type is one of the signed or unsigned integer types.
659 template<typename _Tp>
660 using __is_standard_integer
661 = __or_<__is_signed_integer<_Tp>, __is_unsigned_integer<_Tp>>;
662
663 // __void_t (std::void_t for C++11)
664 template<typename...> using __void_t = void;
665
666 // Utility to detect referenceable types ([defns.referenceable]).
667
668 template<typename _Tp, typename = void>
669 struct __is_referenceable
670 : public false_type
671 { };
672
673 template<typename _Tp>
674 struct __is_referenceable<_Tp, __void_t<_Tp&>>
675 : public true_type
676 { };
677 /// @endcond
678
679 // Type properties.
680
681 /// is_const
682 template<typename>
683 struct is_const
684 : public false_type { };
685
686 template<typename _Tp>
687 struct is_const<_Tp const>
688 : public true_type { };
689
690 /// is_volatile
691 template<typename>
692 struct is_volatile
693 : public false_type { };
694
695 template<typename _Tp>
696 struct is_volatile<_Tp volatile>
697 : public true_type { };
698
699 /// is_trivial
700 template<typename _Tp>
701 struct is_trivial
702 : public integral_constant<bool, __is_trivial(_Tp)>
703 {
704 static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
705 "template argument must be a complete class or an unbounded array");
706 };
707
708 /// is_trivially_copyable
709 template<typename _Tp>
710 struct is_trivially_copyable
711 : public integral_constant<bool, __is_trivially_copyable(_Tp)>
712 {
713 static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
714 "template argument must be a complete class or an unbounded array");
715 };
716
717 /// is_standard_layout
718 template<typename _Tp>
719 struct is_standard_layout
720 : public integral_constant<bool, __is_standard_layout(_Tp)>
721 {
722 static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
723 "template argument must be a complete class or an unbounded array");
724 };
725
726 /** is_pod (deprecated in C++20)
727 * @deprecated Use `is_standard_layout && is_trivial` instead.
728 */
729 // Could use is_standard_layout && is_trivial instead of the builtin.
730 template<typename _Tp>
731 struct
732 _GLIBCXX20_DEPRECATED("use is_standard_layout && is_trivial instead")
733 is_pod
734 : public integral_constant<bool, __is_pod(_Tp)>
735 {
736 static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
737 "template argument must be a complete class or an unbounded array");
738 };
739
740 /** is_literal_type
741 * @deprecated Deprecated in C++20. The idea of a literal type isn't useful.
742 */
743 template<typename _Tp>
744 struct
745 _GLIBCXX17_DEPRECATED
746 is_literal_type
747 : public integral_constant<bool, __is_literal_type(_Tp)>
748 {
749 static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
750 "template argument must be a complete class or an unbounded array");
751 };
752
753 /// is_empty
754 template<typename _Tp>
755 struct is_empty
756 : public integral_constant<bool, __is_empty(_Tp)>
757 { };
758
759 /// is_polymorphic
760 template<typename _Tp>
761 struct is_polymorphic
762 : public integral_constant<bool, __is_polymorphic(_Tp)>
763 { };
764
765#if __cplusplus >= 201402L
766#define __cpp_lib_is_final 201402L
767 /// is_final
768 /// @since C++14
769 template<typename _Tp>
770 struct is_final
771 : public integral_constant<bool, __is_final(_Tp)>
772 { };
773#endif
774
775 /// is_abstract
776 template<typename _Tp>
777 struct is_abstract
778 : public integral_constant<bool, __is_abstract(_Tp)>
779 { };
780
781 /// @cond undocumented
782 template<typename _Tp,
783 bool = is_arithmetic<_Tp>::value>
784 struct __is_signed_helper
785 : public false_type { };
786
787 template<typename _Tp>
788 struct __is_signed_helper<_Tp, true>
789 : public integral_constant<bool, _Tp(-1) < _Tp(0)>
790 { };
791 /// @endcond
792
793 /// is_signed
794 template<typename _Tp>
795 struct is_signed
796 : public __is_signed_helper<_Tp>::type
797 { };
798
799 /// is_unsigned
800 template<typename _Tp>
801 struct is_unsigned
802 : public __and_<is_arithmetic<_Tp>, __not_<is_signed<_Tp>>>
803 { };
804
805 /// @cond undocumented
806 template<typename _Tp, typename _Up = _Tp&&>
807 _Up
808 __declval(int);
809
810 template<typename _Tp>
811 _Tp
812 __declval(long);
813 /// @endcond
814
815 template<typename _Tp>
816 auto declval() noexcept -> decltype(__declval<_Tp>(0));
817
818 template<typename, unsigned = 0>
819 struct extent;
820
821 template<typename>
822 struct remove_all_extents;
823
824 /// @cond undocumented
825 template<typename _Tp>
826 struct __is_array_known_bounds
827 : public integral_constant<bool, (extent<_Tp>::value > 0)>
828 { };
829
830 template<typename _Tp>
831 struct __is_array_unknown_bounds
832 : public __and_<is_array<_Tp>, __not_<extent<_Tp>>>
833 { };
834
835 // Destructible and constructible type properties.
836
837 // In N3290 is_destructible does not say anything about function
838 // types and abstract types, see LWG 2049. This implementation
839 // describes function types as non-destructible and all complete
840 // object types as destructible, iff the explicit destructor
841 // call expression is wellformed.
842 struct __do_is_destructible_impl
843 {
844 template<typename _Tp, typename = decltype(declval<_Tp&>().~_Tp())>
845 static true_type __test(int);
846
847 template<typename>
848 static false_type __test(...);
849 };
850
851 template<typename _Tp>
852 struct __is_destructible_impl
853 : public __do_is_destructible_impl
854 {
855 typedef decltype(__test<_Tp>(0)) type;
856 };
857
858 template<typename _Tp,
859 bool = __or_<is_void<_Tp>,
860 __is_array_unknown_bounds<_Tp>,
861 is_function<_Tp>>::value,
862 bool = __or_<is_reference<_Tp>, is_scalar<_Tp>>::value>
863 struct __is_destructible_safe;
864
865 template<typename _Tp>
866 struct __is_destructible_safe<_Tp, false, false>
867 : public __is_destructible_impl<typename
868 remove_all_extents<_Tp>::type>::type
869 { };
870
871 template<typename _Tp>
872 struct __is_destructible_safe<_Tp, true, false>
873 : public false_type { };
874
875 template<typename _Tp>
876 struct __is_destructible_safe<_Tp, false, true>
877 : public true_type { };
878 /// @endcond
879
880 /// is_destructible
881 template<typename _Tp>
882 struct is_destructible
883 : public __is_destructible_safe<_Tp>::type
884 {
885 static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
886 "template argument must be a complete class or an unbounded array");
887 };
888
889 /// @cond undocumented
890
891 // is_nothrow_destructible requires that is_destructible is
892 // satisfied as well. We realize that by mimicing the
893 // implementation of is_destructible but refer to noexcept(expr)
894 // instead of decltype(expr).
895 struct __do_is_nt_destructible_impl
896 {
897 template<typename _Tp>
898 static __bool_constant<noexcept(declval<_Tp&>().~_Tp())>
899 __test(int);
900
901 template<typename>
902 static false_type __test(...);
903 };
904
905 template<typename _Tp>
906 struct __is_nt_destructible_impl
907 : public __do_is_nt_destructible_impl
908 {
909 typedef decltype(__test<_Tp>(0)) type;
910 };
911
912 template<typename _Tp,
913 bool = __or_<is_void<_Tp>,
914 __is_array_unknown_bounds<_Tp>,
915 is_function<_Tp>>::value,
916 bool = __or_<is_reference<_Tp>, is_scalar<_Tp>>::value>
917 struct __is_nt_destructible_safe;
918
919 template<typename _Tp>
920 struct __is_nt_destructible_safe<_Tp, false, false>
921 : public __is_nt_destructible_impl<typename
922 remove_all_extents<_Tp>::type>::type
923 { };
924
925 template<typename _Tp>
926 struct __is_nt_destructible_safe<_Tp, true, false>
927 : public false_type { };
928
929 template<typename _Tp>
930 struct __is_nt_destructible_safe<_Tp, false, true>
931 : public true_type { };
932 /// @endcond
933
934 /// is_nothrow_destructible
935 template<typename _Tp>
936 struct is_nothrow_destructible
937 : public __is_nt_destructible_safe<_Tp>::type
938 {
939 static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
940 "template argument must be a complete class or an unbounded array");
941 };
942
943 /// @cond undocumented
944 template<typename _Tp, typename... _Args>
945 struct __is_constructible_impl
946 : public __bool_constant<__is_constructible(_Tp, _Args...)>
947 { };
948 /// @endcond
949
950 /// is_constructible
951 template<typename _Tp, typename... _Args>
952 struct is_constructible
953 : public __is_constructible_impl<_Tp, _Args...>
954 {
955 static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
956 "template argument must be a complete class or an unbounded array");
957 };
958
959 /// is_default_constructible
960 template<typename _Tp>
961 struct is_default_constructible
962 : public __is_constructible_impl<_Tp>::type
963 {
964 static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
965 "template argument must be a complete class or an unbounded array");
966 };
967
968 /// @cond undocumented
969 template<typename _Tp, bool = __is_referenceable<_Tp>::value>
970 struct __is_copy_constructible_impl;
971
972 template<typename _Tp>
973 struct __is_copy_constructible_impl<_Tp, false>
974 : public false_type { };
975
976 template<typename _Tp>
977 struct __is_copy_constructible_impl<_Tp, true>
978 : public __is_constructible_impl<_Tp, const _Tp&>
979 { };
980 /// @endcond
981
982 /// is_copy_constructible
983 template<typename _Tp>
984 struct is_copy_constructible
985 : public __is_copy_constructible_impl<_Tp>
986 {
987 static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
988 "template argument must be a complete class or an unbounded array");
989 };
990
991 /// @cond undocumented
992 template<typename _Tp, bool = __is_referenceable<_Tp>::value>
993 struct __is_move_constructible_impl;
994
995 template<typename _Tp>
996 struct __is_move_constructible_impl<_Tp, false>
997 : public false_type { };
998
999 template<typename _Tp>
1000 struct __is_move_constructible_impl<_Tp, true>
1001 : public __is_constructible_impl<_Tp, _Tp&&>
1002 { };
1003 /// @endcond
1004
1005 /// is_move_constructible
1006 template<typename _Tp>
1007 struct is_move_constructible
1008 : public __is_move_constructible_impl<_Tp>
1009 {
1010 static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
1011 "template argument must be a complete class or an unbounded array");
1012 };
1013
1014 /// @cond undocumented
1015 template<typename _Tp, typename... _Args>
1016 using __is_nothrow_constructible_impl
1017 = __bool_constant<__is_nothrow_constructible(_Tp, _Args...)>;
1018 /// @endcond
1019
1020 /// is_nothrow_constructible
1021 template<typename _Tp, typename... _Args>
1022 struct is_nothrow_constructible
1023 : public __is_nothrow_constructible_impl<_Tp, _Args...>::type
1024 {
1025 static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
1026 "template argument must be a complete class or an unbounded array");
1027 };
1028
1029 /// is_nothrow_default_constructible
1030 template<typename _Tp>
1031 struct is_nothrow_default_constructible
1032 : public __bool_constant<__is_nothrow_constructible(_Tp)>
1033 {
1034 static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
1035 "template argument must be a complete class or an unbounded array");
1036 };
1037
1038 /// @cond undocumented
1039 template<typename _Tp, bool = __is_referenceable<_Tp>::value>
1040 struct __is_nothrow_copy_constructible_impl;
1041
1042 template<typename _Tp>
1043 struct __is_nothrow_copy_constructible_impl<_Tp, false>
1044 : public false_type { };
1045
1046 template<typename _Tp>
1047 struct __is_nothrow_copy_constructible_impl<_Tp, true>
1048 : public __is_nothrow_constructible_impl<_Tp, const _Tp&>
1049 { };
1050 /// @endcond
1051
1052 /// is_nothrow_copy_constructible
1053 template<typename _Tp>
1054 struct is_nothrow_copy_constructible
1055 : public __is_nothrow_copy_constructible_impl<_Tp>::type
1056 {
1057 static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
1058 "template argument must be a complete class or an unbounded array");
1059 };
1060
1061 /// @cond undocumented
1062 template<typename _Tp, bool = __is_referenceable<_Tp>::value>
1063 struct __is_nothrow_move_constructible_impl;
1064
1065 template<typename _Tp>
1066 struct __is_nothrow_move_constructible_impl<_Tp, false>
1067 : public false_type { };
1068
1069 template<typename _Tp>
1070 struct __is_nothrow_move_constructible_impl<_Tp, true>
1071 : public __is_nothrow_constructible_impl<_Tp, _Tp&&>
1072 { };
1073 /// @endcond
1074
1075 /// is_nothrow_move_constructible
1076 template<typename _Tp>
1077 struct is_nothrow_move_constructible
1078 : public __is_nothrow_move_constructible_impl<_Tp>::type
1079 {
1080 static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
1081 "template argument must be a complete class or an unbounded array");
1082 };
1083
1084 /// is_assignable
1085 template<typename _Tp, typename _Up>
1086 struct is_assignable
1087 : public __bool_constant<__is_assignable(_Tp, _Up)>
1088 {
1089 static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
1090 "template argument must be a complete class or an unbounded array");
1091 };
1092
1093 template<typename _Tp, bool = __is_referenceable<_Tp>::value>
1094 struct __is_copy_assignable_impl;
1095
1096 template<typename _Tp>
1097 struct __is_copy_assignable_impl<_Tp, false>
1098 : public false_type { };
1099
1100 template<typename _Tp>
1101 struct __is_copy_assignable_impl<_Tp, true>
1102 : public __bool_constant<__is_assignable(_Tp&, const _Tp&)>
1103 { };
1104
1105 /// is_copy_assignable
1106 template<typename _Tp>
1107 struct is_copy_assignable
1108 : public __is_copy_assignable_impl<_Tp>::type
1109 {
1110 static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
1111 "template argument must be a complete class or an unbounded array");
1112 };
1113
1114 template<typename _Tp, bool = __is_referenceable<_Tp>::value>
1115 struct __is_move_assignable_impl;
1116
1117 template<typename _Tp>
1118 struct __is_move_assignable_impl<_Tp, false>
1119 : public false_type { };
1120
1121 template<typename _Tp>
1122 struct __is_move_assignable_impl<_Tp, true>
1123 : public __bool_constant<__is_assignable(_Tp&, _Tp&&)>
1124 { };
1125
1126 /// is_move_assignable
1127 template<typename _Tp>
1128 struct is_move_assignable
1129 : public __is_move_assignable_impl<_Tp>::type
1130 {
1131 static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
1132 "template argument must be a complete class or an unbounded array");
1133 };
1134
1135 template<typename _Tp, typename _Up>
1136 using __is_nothrow_assignable_impl
1137 = __bool_constant<__is_nothrow_assignable(_Tp, _Up)>;
1138
1139 /// is_nothrow_assignable
1140 template<typename _Tp, typename _Up>
1141 struct is_nothrow_assignable
1142 : public __is_nothrow_assignable_impl<_Tp, _Up>
1143 {
1144 static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
1145 "template argument must be a complete class or an unbounded array");
1146 };
1147
1148 template<typename _Tp, bool = __is_referenceable<_Tp>::value>
1149 struct __is_nt_copy_assignable_impl;
1150
1151 template<typename _Tp>
1152 struct __is_nt_copy_assignable_impl<_Tp, false>
1153 : public false_type { };
1154
1155 template<typename _Tp>
1156 struct __is_nt_copy_assignable_impl<_Tp, true>
1157 : public __is_nothrow_assignable_impl<_Tp&, const _Tp&>
1158 { };
1159
1160 /// is_nothrow_copy_assignable
1161 template<typename _Tp>
1162 struct is_nothrow_copy_assignable
1163 : public __is_nt_copy_assignable_impl<_Tp>
1164 {
1165 static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
1166 "template argument must be a complete class or an unbounded array");
1167 };
1168
1169 template<typename _Tp, bool = __is_referenceable<_Tp>::value>
1170 struct __is_nt_move_assignable_impl;
1171
1172 template<typename _Tp>
1173 struct __is_nt_move_assignable_impl<_Tp, false>
1174 : public false_type { };
1175
1176 template<typename _Tp>
1177 struct __is_nt_move_assignable_impl<_Tp, true>
1178 : public __is_nothrow_assignable_impl<_Tp&, _Tp&&>
1179 { };
1180
1181 /// is_nothrow_move_assignable
1182 template<typename _Tp>
1183 struct is_nothrow_move_assignable
1184 : public __is_nt_move_assignable_impl<_Tp>
1185 {
1186 static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
1187 "template argument must be a complete class or an unbounded array");
1188 };
1189
1190 /// is_trivially_constructible
1191 template<typename _Tp, typename... _Args>
1192 struct is_trivially_constructible
1193 : public __bool_constant<__is_trivially_constructible(_Tp, _Args...)>
1194 {
1195 static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
1196 "template argument must be a complete class or an unbounded array");
1197 };
1198
1199 /// is_trivially_default_constructible
1200 template<typename _Tp>
1201 struct is_trivially_default_constructible
1202 : public __bool_constant<__is_trivially_constructible(_Tp)>
1203 {
1204 static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
1205 "template argument must be a complete class or an unbounded array");
1206 };
1207
1208 struct __do_is_implicitly_default_constructible_impl
1209 {
1210 template <typename _Tp>
1211 static void __helper(const _Tp&);
1212
1213 template <typename _Tp>
1214 static true_type __test(const _Tp&,
1215 decltype(__helper<const _Tp&>({}))* = 0);
1216
1217 static false_type __test(...);
1218 };
1219
1220 template<typename _Tp>
1221 struct __is_implicitly_default_constructible_impl
1222 : public __do_is_implicitly_default_constructible_impl
1223 {
1224 typedef decltype(__test(declval<_Tp>())) type;
1225 };
1226
1227 template<typename _Tp>
1228 struct __is_implicitly_default_constructible_safe
1229 : public __is_implicitly_default_constructible_impl<_Tp>::type
1230 { };
1231
1232 template <typename _Tp>
1233 struct __is_implicitly_default_constructible
1234 : public __and_<__is_constructible_impl<_Tp>,
1235 __is_implicitly_default_constructible_safe<_Tp>>
1236 { };
1237
1238 template<typename _Tp, bool = __is_referenceable<_Tp>::value>
1239 struct __is_trivially_copy_constructible_impl;
1240
1241 template<typename _Tp>
1242 struct __is_trivially_copy_constructible_impl<_Tp, false>
1243 : public false_type { };
1244
1245 template<typename _Tp>
1246 struct __is_trivially_copy_constructible_impl<_Tp, true>
1247 : public __and_<__is_copy_constructible_impl<_Tp>,
1248 integral_constant<bool,
1249 __is_trivially_constructible(_Tp, const _Tp&)>>
1250 { };
1251
1252 /// is_trivially_copy_constructible
1253 template<typename _Tp>
1254 struct is_trivially_copy_constructible
1255 : public __is_trivially_copy_constructible_impl<_Tp>
1256 {
1257 static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
1258 "template argument must be a complete class or an unbounded array");
1259 };
1260
1261 template<typename _Tp, bool = __is_referenceable<_Tp>::value>
1262 struct __is_trivially_move_constructible_impl;
1263
1264 template<typename _Tp>
1265 struct __is_trivially_move_constructible_impl<_Tp, false>
1266 : public false_type { };
1267
1268 template<typename _Tp>
1269 struct __is_trivially_move_constructible_impl<_Tp, true>
1270 : public __and_<__is_move_constructible_impl<_Tp>,
1271 integral_constant<bool,
1272 __is_trivially_constructible(_Tp, _Tp&&)>>
1273 { };
1274
1275 /// is_trivially_move_constructible
1276 template<typename _Tp>
1277 struct is_trivially_move_constructible
1278 : public __is_trivially_move_constructible_impl<_Tp>
1279 {
1280 static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
1281 "template argument must be a complete class or an unbounded array");
1282 };
1283
1284 /// is_trivially_assignable
1285 template<typename _Tp, typename _Up>
1286 struct is_trivially_assignable
1287 : public __bool_constant<__is_trivially_assignable(_Tp, _Up)>
1288 {
1289 static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
1290 "template argument must be a complete class or an unbounded array");
1291 };
1292
1293 template<typename _Tp, bool = __is_referenceable<_Tp>::value>
1294 struct __is_trivially_copy_assignable_impl;
1295
1296 template<typename _Tp>
1297 struct __is_trivially_copy_assignable_impl<_Tp, false>
1298 : public false_type { };
1299
1300 template<typename _Tp>
1301 struct __is_trivially_copy_assignable_impl<_Tp, true>
1302 : public __bool_constant<__is_trivially_assignable(_Tp&, const _Tp&)>
1303 { };
1304
1305 /// is_trivially_copy_assignable
1306 template<typename _Tp>
1307 struct is_trivially_copy_assignable
1308 : public __is_trivially_copy_assignable_impl<_Tp>
1309 {
1310 static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
1311 "template argument must be a complete class or an unbounded array");
1312 };
1313
1314 template<typename _Tp, bool = __is_referenceable<_Tp>::value>
1315 struct __is_trivially_move_assignable_impl;
1316
1317 template<typename _Tp>
1318 struct __is_trivially_move_assignable_impl<_Tp, false>
1319 : public false_type { };
1320
1321 template<typename _Tp>
1322 struct __is_trivially_move_assignable_impl<_Tp, true>
1323 : public __bool_constant<__is_trivially_assignable(_Tp&, _Tp&&)>
1324 { };
1325
1326 /// is_trivially_move_assignable
1327 template<typename _Tp>
1328 struct is_trivially_move_assignable
1329 : public __is_trivially_move_assignable_impl<_Tp>
1330 {
1331 static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
1332 "template argument must be a complete class or an unbounded array");
1333 };
1334
1335 /// is_trivially_destructible
1336 template<typename _Tp>
1337 struct is_trivially_destructible
1338 : public __and_<__is_destructible_safe<_Tp>,
1339 __bool_constant<__has_trivial_destructor(_Tp)>>
1340 {
1341 static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
1342 "template argument must be a complete class or an unbounded array");
1343 };
1344
1345
1346 /// has_virtual_destructor
1347 template<typename _Tp>
1348 struct has_virtual_destructor
1349 : public integral_constant<bool, __has_virtual_destructor(_Tp)>
1350 {
1351 static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
1352 "template argument must be a complete class or an unbounded array");
1353 };
1354
1355
1356 // type property queries.
1357
1358 /// alignment_of
1359 template<typename _Tp>
1360 struct alignment_of
1361 : public integral_constant<std::size_t, alignof(_Tp)>
1362 {
1363 static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
1364 "template argument must be a complete class or an unbounded array");
1365 };
1366
1367 /// rank
1368 template<typename>
1369 struct rank
1370 : public integral_constant<std::size_t, 0> { };
1371
1372 template<typename _Tp, std::size_t _Size>
1373 struct rank<_Tp[_Size]>
1374 : public integral_constant<std::size_t, 1 + rank<_Tp>::value> { };
1375
1376 template<typename _Tp>
1377 struct rank<_Tp[]>
1378 : public integral_constant<std::size_t, 1 + rank<_Tp>::value> { };
1379
1380 /// extent
1381 template<typename, unsigned _Uint>
1382 struct extent
1383 : public integral_constant<std::size_t, 0> { };
1384
1385 template<typename _Tp, unsigned _Uint, std::size_t _Size>
1386 struct extent<_Tp[_Size], _Uint>
1387 : public integral_constant<std::size_t,
1388 _Uint == 0 ? _Size : extent<_Tp,
1389 _Uint - 1>::value>
1390 { };
1391
1392 template<typename _Tp, unsigned _Uint>
1393 struct extent<_Tp[], _Uint>
1394 : public integral_constant<std::size_t,
1395 _Uint == 0 ? 0 : extent<_Tp,
1396 _Uint - 1>::value>
1397 { };
1398
1399
1400 // Type relations.
1401
1402 /// is_same
1403 template<typename _Tp, typename _Up>
1404 struct is_same
1405#ifdef _GLIBCXX_HAVE_BUILTIN_IS_SAME
1406 : public integral_constant<bool, __is_same(_Tp, _Up)>
1407#else
1408 : public false_type
1409#endif
1410 { };
1411
1412#ifndef _GLIBCXX_HAVE_BUILTIN_IS_SAME
1413 template<typename _Tp>
1414 struct is_same<_Tp, _Tp>
1415 : public true_type
1416 { };
1417#endif
1418
1419 /// is_base_of
1420 template<typename _Base, typename _Derived>
1421 struct is_base_of
1422 : public integral_constant<bool, __is_base_of(_Base, _Derived)>
1423 { };
1424
1425 template<typename _From, typename _To,
1426 bool = __or_<is_void<_From>, is_function<_To>,
1427 is_array<_To>>::value>
1428 struct __is_convertible_helper
1429 {
1430 typedef typename is_void<_To>::type type;
1431 };
1432
1433#pragma GCC diagnostic push
1434#pragma GCC diagnostic ignored "-Wctor-dtor-privacy"
1435 template<typename _From, typename _To>
1436 class __is_convertible_helper<_From, _To, false>
1437 {
1438 template<typename _To1>
1439 static void __test_aux(_To1) noexcept;
1440
1441 template<typename _From1, typename _To1,
1442 typename = decltype(__test_aux<_To1>(std::declval<_From1>()))>
1443 static true_type
1444 __test(int);
1445
1446 template<typename, typename>
1447 static false_type
1448 __test(...);
1449
1450 public:
1451 typedef decltype(__test<_From, _To>(0)) type;
1452 };
1453#pragma GCC diagnostic pop
1454
1455 /// is_convertible
1456 template<typename _From, typename _To>
1457 struct is_convertible
1458 : public __is_convertible_helper<_From, _To>::type
1459 { };
1460
1461 // helper trait for unique_ptr<T[]>, shared_ptr<T[]>, and span<T, N>
1462 template<typename _ToElementType, typename _FromElementType>
1463 using __is_array_convertible
1464 = is_convertible<_FromElementType(*)[], _ToElementType(*)[]>;
1465
1466 template<typename _From, typename _To,
1467 bool = __or_<is_void<_From>, is_function<_To>,
1468 is_array<_To>>::value>
1469 struct __is_nt_convertible_helper
1470 : is_void<_To>
1471 { };
1472
1473#pragma GCC diagnostic push
1474#pragma GCC diagnostic ignored "-Wctor-dtor-privacy"
1475 template<typename _From, typename _To>
1476 class __is_nt_convertible_helper<_From, _To, false>
1477 {
1478 template<typename _To1>
1479 static void __test_aux(_To1) noexcept;
1480
1481 template<typename _From1, typename _To1>
1482 static
1483 __bool_constant<noexcept(__test_aux<_To1>(std::declval<_From1>()))>
1484 __test(int);
1485
1486 template<typename, typename>
1487 static false_type
1488 __test(...);
1489
1490 public:
1491 using type = decltype(__test<_From, _To>(0));
1492 };
1493#pragma GCC diagnostic pop
1494
1495#if __cplusplus > 201703L
1496#define __cpp_lib_is_nothrow_convertible 201806L
1497 /// is_nothrow_convertible
1498 template<typename _From, typename _To>
1499 struct is_nothrow_convertible
1500 : public __is_nt_convertible_helper<_From, _To>::type
1501 { };
1502
1503 /// is_nothrow_convertible_v
1504 template<typename _From, typename _To>
1505 inline constexpr bool is_nothrow_convertible_v
1506 = is_nothrow_convertible<_From, _To>::value;
1507#endif // C++2a
1508
1509 // Const-volatile modifications.
1510
1511 /// remove_const
1512 template<typename _Tp>
1513 struct remove_const
1514 { typedef _Tp type; };
1515
1516 template<typename _Tp>
1517 struct remove_const<_Tp const>
1518 { typedef _Tp type; };
1519
1520 /// remove_volatile
1521 template<typename _Tp>
1522 struct remove_volatile
1523 { typedef _Tp type; };
1524
1525 template<typename _Tp>
1526 struct remove_volatile<_Tp volatile>
1527 { typedef _Tp type; };
1528
1529 /// remove_cv
1530 template<typename _Tp>
1531 struct remove_cv
1532 { using type = _Tp; };
1533
1534 template<typename _Tp>
1535 struct remove_cv<const _Tp>
1536 { using type = _Tp; };
1537
1538 template<typename _Tp>
1539 struct remove_cv<volatile _Tp>
1540 { using type = _Tp; };
1541
1542 template<typename _Tp>
1543 struct remove_cv<const volatile _Tp>
1544 { using type = _Tp; };
1545
1546 /// add_const
1547 template<typename _Tp>
1548 struct add_const
1549 { typedef _Tp const type; };
1550
1551 /// add_volatile
1552 template<typename _Tp>
1553 struct add_volatile
1554 { typedef _Tp volatile type; };
1555
1556 /// add_cv
1557 template<typename _Tp>
1558 struct add_cv
1559 {
1560 typedef typename
1561 add_const<typename add_volatile<_Tp>::type>::type type;
1562 };
1563
1564#if __cplusplus > 201103L
1565
1566#define __cpp_lib_transformation_trait_aliases 201304
1567
1568 /// Alias template for remove_const
1569 template<typename _Tp>
1570 using remove_const_t = typename remove_const<_Tp>::type;
1571
1572 /// Alias template for remove_volatile
1573 template<typename _Tp>
1574 using remove_volatile_t = typename remove_volatile<_Tp>::type;
1575
1576 /// Alias template for remove_cv
1577 template<typename _Tp>
1578 using remove_cv_t = typename remove_cv<_Tp>::type;
1579
1580 /// Alias template for add_const
1581 template<typename _Tp>
1582 using add_const_t = typename add_const<_Tp>::type;
1583
1584 /// Alias template for add_volatile
1585 template<typename _Tp>
1586 using add_volatile_t = typename add_volatile<_Tp>::type;
1587
1588 /// Alias template for add_cv
1589 template<typename _Tp>
1590 using add_cv_t = typename add_cv<_Tp>::type;
1591#endif
1592
1593 // Reference transformations.
1594
1595 /// remove_reference
1596 template<typename _Tp>
1597 struct remove_reference
1598 { typedef _Tp type; };
1599
1600 template<typename _Tp>
1601 struct remove_reference<_Tp&>
1602 { typedef _Tp type; };
1603
1604 template<typename _Tp>
1605 struct remove_reference<_Tp&&>
1606 { typedef _Tp type; };
1607
1608 template<typename _Tp, bool = __is_referenceable<_Tp>::value>
1609 struct __add_lvalue_reference_helper
1610 { typedef _Tp type; };
1611
1612 template<typename _Tp>
1613 struct __add_lvalue_reference_helper<_Tp, true>
1614 { typedef _Tp& type; };
1615
1616 /// add_lvalue_reference
1617 template<typename _Tp>
1618 struct add_lvalue_reference
1619 : public __add_lvalue_reference_helper<_Tp>
1620 { };
1621
1622 template<typename _Tp, bool = __is_referenceable<_Tp>::value>
1623 struct __add_rvalue_reference_helper
1624 { typedef _Tp type; };
1625
1626 template<typename _Tp>
1627 struct __add_rvalue_reference_helper<_Tp, true>
1628 { typedef _Tp&& type; };
1629
1630 /// add_rvalue_reference
1631 template<typename _Tp>
1632 struct add_rvalue_reference
1633 : public __add_rvalue_reference_helper<_Tp>
1634 { };
1635
1636#if __cplusplus > 201103L
1637 /// Alias template for remove_reference
1638 template<typename _Tp>
1639 using remove_reference_t = typename remove_reference<_Tp>::type;
1640
1641 /// Alias template for add_lvalue_reference
1642 template<typename _Tp>
1643 using add_lvalue_reference_t = typename add_lvalue_reference<_Tp>::type;
1644
1645 /// Alias template for add_rvalue_reference
1646 template<typename _Tp>
1647 using add_rvalue_reference_t = typename add_rvalue_reference<_Tp>::type;
1648#endif
1649
1650 // Sign modifications.
1651
1652 /// @cond undocumented
1653
1654 // Utility for constructing identically cv-qualified types.
1655 template<typename _Unqualified, bool _IsConst, bool _IsVol>
1656 struct __cv_selector;
1657
1658 template<typename _Unqualified>
1659 struct __cv_selector<_Unqualified, false, false>
1660 { typedef _Unqualified __type; };
1661
1662 template<typename _Unqualified>
1663 struct __cv_selector<_Unqualified, false, true>
1664 { typedef volatile _Unqualified __type; };
1665
1666 template<typename _Unqualified>
1667 struct __cv_selector<_Unqualified, true, false>
1668 { typedef const _Unqualified __type; };
1669
1670 template<typename _Unqualified>
1671 struct __cv_selector<_Unqualified, true, true>
1672 { typedef const volatile _Unqualified __type; };
1673
1674 template<typename _Qualified, typename _Unqualified,
1675 bool _IsConst = is_const<_Qualified>::value,
1676 bool _IsVol = is_volatile<_Qualified>::value>
1677 class __match_cv_qualifiers
1678 {
1679 typedef __cv_selector<_Unqualified, _IsConst, _IsVol> __match;
1680
1681 public:
1682 typedef typename __match::__type __type;
1683 };
1684
1685 // Utility for finding the unsigned versions of signed integral types.
1686 template<typename _Tp>
1687 struct __make_unsigned
1688 { typedef _Tp __type; };
1689
1690 template<>
1691 struct __make_unsigned<char>
1692 { typedef unsigned char __type; };
1693
1694 template<>
1695 struct __make_unsigned<signed char>
1696 { typedef unsigned char __type; };
1697
1698 template<>
1699 struct __make_unsigned<short>
1700 { typedef unsigned short __type; };
1701
1702 template<>
1703 struct __make_unsigned<int>
1704 { typedef unsigned int __type; };
1705
1706 template<>
1707 struct __make_unsigned<long>
1708 { typedef unsigned long __type; };
1709
1710 template<>
1711 struct __make_unsigned<long long>
1712 { typedef unsigned long long __type; };
1713
1714#if defined(__GLIBCXX_TYPE_INT_N_0)
1715 template<>
1716 struct __make_unsigned<__GLIBCXX_TYPE_INT_N_0>
1717 { typedef unsigned __GLIBCXX_TYPE_INT_N_0 __type; };
1718#endif
1719#if defined(__GLIBCXX_TYPE_INT_N_1)
1720 template<>
1721 struct __make_unsigned<__GLIBCXX_TYPE_INT_N_1>
1722 { typedef unsigned __GLIBCXX_TYPE_INT_N_1 __type; };
1723#endif
1724#if defined(__GLIBCXX_TYPE_INT_N_2)
1725 template<>
1726 struct __make_unsigned<__GLIBCXX_TYPE_INT_N_2>
1727 { typedef unsigned __GLIBCXX_TYPE_INT_N_2 __type; };
1728#endif
1729#if defined(__GLIBCXX_TYPE_INT_N_3)
1730 template<>
1731 struct __make_unsigned<__GLIBCXX_TYPE_INT_N_3>
1732 { typedef unsigned __GLIBCXX_TYPE_INT_N_3 __type; };
1733#endif
1734
1735 // Select between integral and enum: not possible to be both.
1736 template<typename _Tp,
1737 bool _IsInt = is_integral<_Tp>::value,
1738 bool _IsEnum = is_enum<_Tp>::value>
1739 class __make_unsigned_selector;
1740
1741 template<typename _Tp>
1742 class __make_unsigned_selector<_Tp, true, false>
1743 {
1744 using __unsigned_type
1745 = typename __make_unsigned<__remove_cv_t<_Tp>>::__type;
1746
1747 public:
1748 using __type
1749 = typename __match_cv_qualifiers<_Tp, __unsigned_type>::__type;
1750 };
1751
1752 class __make_unsigned_selector_base
1753 {
1754 protected:
1755 template<typename...> struct _List { };
1756
1757 template<typename _Tp, typename... _Up>
1758 struct _List<_Tp, _Up...> : _List<_Up...>
1759 { static constexpr size_t __size = sizeof(_Tp); };
1760
1761 template<size_t _Sz, typename _Tp, bool = (_Sz <= _Tp::__size)>
1762 struct __select;
1763
1764 template<size_t _Sz, typename _Uint, typename... _UInts>
1765 struct __select<_Sz, _List<_Uint, _UInts...>, true>
1766 { using __type = _Uint; };
1767
1768 template<size_t _Sz, typename _Uint, typename... _UInts>
1769 struct __select<_Sz, _List<_Uint, _UInts...>, false>
1770 : __select<_Sz, _List<_UInts...>>
1771 { };
1772 };
1773
1774 // Choose unsigned integer type with the smallest rank and same size as _Tp
1775 template<typename _Tp>
1776 class __make_unsigned_selector<_Tp, false, true>
1777 : __make_unsigned_selector_base
1778 {
1779 // With -fshort-enums, an enum may be as small as a char.
1780 using _UInts = _List<unsigned char, unsigned short, unsigned int,
1781 unsigned long, unsigned long long>;
1782
1783 using __unsigned_type = typename __select<sizeof(_Tp), _UInts>::__type;
1784
1785 public:
1786 using __type
1787 = typename __match_cv_qualifiers<_Tp, __unsigned_type>::__type;
1788 };
1789
1790 // wchar_t, char8_t, char16_t and char32_t are integral types but are
1791 // neither signed integer types nor unsigned integer types, so must be
1792 // transformed to the unsigned integer type with the smallest rank.
1793 // Use the partial specialization for enumeration types to do that.
1794#ifdef __WCHAR_TYPE__
1795 template<>
1796 struct __make_unsigned<wchar_t>
1797 {
1798 using __type
1799 = typename __make_unsigned_selector<wchar_t, false, true>::__type;
1800 };
1801#endif
1802
1803#ifdef _GLIBCXX_USE_CHAR8_T
1804 template<>
1805 struct __make_unsigned<char8_t>
1806 {
1807 using __type
1808 = typename __make_unsigned_selector<char8_t, false, true>::__type;
1809 };
1810#endif
1811
1812 template<>
1813 struct __make_unsigned<char16_t>
1814 {
1815 using __type
1816 = typename __make_unsigned_selector<char16_t, false, true>::__type;
1817 };
1818
1819 template<>
1820 struct __make_unsigned<char32_t>
1821 {
1822 using __type
1823 = typename __make_unsigned_selector<char32_t, false, true>::__type;
1824 };
1825 /// @endcond
1826
1827 // Given an integral/enum type, return the corresponding unsigned
1828 // integer type.
1829 // Primary template.
1830 /// make_unsigned
1831 template<typename _Tp>
1832 struct make_unsigned
1833 { typedef typename __make_unsigned_selector<_Tp>::__type type; };
1834
1835 // Integral, but don't define.
1836 template<>
1837 struct make_unsigned<bool>;
1838
1839 /// @cond undocumented
1840
1841 // Utility for finding the signed versions of unsigned integral types.
1842 template<typename _Tp>
1843 struct __make_signed
1844 { typedef _Tp __type; };
1845
1846 template<>
1847 struct __make_signed<char>
1848 { typedef signed char __type; };
1849
1850 template<>
1851 struct __make_signed<unsigned char>
1852 { typedef signed char __type; };
1853
1854 template<>
1855 struct __make_signed<unsigned short>
1856 { typedef signed short __type; };
1857
1858 template<>
1859 struct __make_signed<unsigned int>
1860 { typedef signed int __type; };
1861
1862 template<>
1863 struct __make_signed<unsigned long>
1864 { typedef signed long __type; };
1865
1866 template<>
1867 struct __make_signed<unsigned long long>
1868 { typedef signed long long __type; };
1869
1870#if defined(__GLIBCXX_TYPE_INT_N_0)
1871 template<>
1872 struct __make_signed<unsigned __GLIBCXX_TYPE_INT_N_0>
1873 { typedef __GLIBCXX_TYPE_INT_N_0 __type; };
1874#endif
1875#if defined(__GLIBCXX_TYPE_INT_N_1)
1876 template<>
1877 struct __make_signed<unsigned __GLIBCXX_TYPE_INT_N_1>
1878 { typedef __GLIBCXX_TYPE_INT_N_1 __type; };
1879#endif
1880#if defined(__GLIBCXX_TYPE_INT_N_2)
1881 template<>
1882 struct __make_signed<unsigned __GLIBCXX_TYPE_INT_N_2>
1883 { typedef __GLIBCXX_TYPE_INT_N_2 __type; };
1884#endif
1885#if defined(__GLIBCXX_TYPE_INT_N_3)
1886 template<>
1887 struct __make_signed<unsigned __GLIBCXX_TYPE_INT_N_3>
1888 { typedef __GLIBCXX_TYPE_INT_N_3 __type; };
1889#endif
1890
1891 // Select between integral and enum: not possible to be both.
1892 template<typename _Tp,
1893 bool _IsInt = is_integral<_Tp>::value,
1894 bool _IsEnum = is_enum<_Tp>::value>
1895 class __make_signed_selector;
1896
1897 template<typename _Tp>
1898 class __make_signed_selector<_Tp, true, false>
1899 {
1900 using __signed_type
1901 = typename __make_signed<__remove_cv_t<_Tp>>::__type;
1902
1903 public:
1904 using __type
1905 = typename __match_cv_qualifiers<_Tp, __signed_type>::__type;
1906 };
1907
1908 // Choose signed integer type with the smallest rank and same size as _Tp
1909 template<typename _Tp>
1910 class __make_signed_selector<_Tp, false, true>
1911 {
1912 typedef typename __make_unsigned_selector<_Tp>::__type __unsigned_type;
1913
1914 public:
1915 typedef typename __make_signed_selector<__unsigned_type>::__type __type;
1916 };
1917
1918 // wchar_t, char16_t and char32_t are integral types but are neither
1919 // signed integer types nor unsigned integer types, so must be
1920 // transformed to the signed integer type with the smallest rank.
1921 // Use the partial specialization for enumeration types to do that.
1922#if defined(__WCHAR_TYPE__)
1923 template<>
1924 struct __make_signed<wchar_t>
1925 {
1926 using __type
1927 = typename __make_signed_selector<wchar_t, false, true>::__type;
1928 };
1929#endif
1930
1931#if defined(_GLIBCXX_USE_CHAR8_T)
1932 template<>
1933 struct __make_signed<char8_t>
1934 {
1935 using __type
1936 = typename __make_signed_selector<char8_t, false, true>::__type;
1937 };
1938#endif
1939
1940 template<>
1941 struct __make_signed<char16_t>
1942 {
1943 using __type
1944 = typename __make_signed_selector<char16_t, false, true>::__type;
1945 };
1946
1947 template<>
1948 struct __make_signed<char32_t>
1949 {
1950 using __type
1951 = typename __make_signed_selector<char32_t, false, true>::__type;
1952 };
1953 /// @endcond
1954
1955 // Given an integral/enum type, return the corresponding signed
1956 // integer type.
1957 // Primary template.
1958 /// make_signed
1959 template<typename _Tp>
1960 struct make_signed
1961 { typedef typename __make_signed_selector<_Tp>::__type type; };
1962
1963 // Integral, but don't define.
1964 template<>
1965 struct make_signed<bool>;
1966
1967#if __cplusplus > 201103L
1968 /// Alias template for make_signed
1969 template<typename _Tp>
1970 using make_signed_t = typename make_signed<_Tp>::type;
1971
1972 /// Alias template for make_unsigned
1973 template<typename _Tp>
1974 using make_unsigned_t = typename make_unsigned<_Tp>::type;
1975#endif
1976
1977 // Array modifications.
1978
1979 /// remove_extent
1980 template<typename _Tp>
1981 struct remove_extent
1982 { typedef _Tp type; };
1983
1984 template<typename _Tp, std::size_t _Size>
1985 struct remove_extent<_Tp[_Size]>
1986 { typedef _Tp type; };
1987
1988 template<typename _Tp>
1989 struct remove_extent<_Tp[]>
1990 { typedef _Tp type; };
1991
1992 /// remove_all_extents
1993 template<typename _Tp>
1994 struct remove_all_extents
1995 { typedef _Tp type; };
1996
1997 template<typename _Tp, std::size_t _Size>
1998 struct remove_all_extents<_Tp[_Size]>
1999 { typedef typename remove_all_extents<_Tp>::type type; };
2000
2001 template<typename _Tp>
2002 struct remove_all_extents<_Tp[]>
2003 { typedef typename remove_all_extents<_Tp>::type type; };
2004
2005#if __cplusplus > 201103L
2006 /// Alias template for remove_extent
2007 template<typename _Tp>
2008 using remove_extent_t = typename remove_extent<_Tp>::type;
2009
2010 /// Alias template for remove_all_extents
2011 template<typename _Tp>
2012 using remove_all_extents_t = typename remove_all_extents<_Tp>::type;
2013#endif
2014
2015 // Pointer modifications.
2016
2017 template<typename _Tp, typename>
2018 struct __remove_pointer_helper
2019 { typedef _Tp type; };
2020
2021 template<typename _Tp, typename _Up>
2022 struct __remove_pointer_helper<_Tp, _Up*>
2023 { typedef _Up type; };
2024
2025 /// remove_pointer
2026 template<typename _Tp>
2027 struct remove_pointer
2028 : public __remove_pointer_helper<_Tp, __remove_cv_t<_Tp>>
2029 { };
2030
2031 template<typename _Tp, bool = __or_<__is_referenceable<_Tp>,
2032 is_void<_Tp>>::value>
2033 struct __add_pointer_helper
2034 { typedef _Tp type; };
2035
2036 template<typename _Tp>
2037 struct __add_pointer_helper<_Tp, true>
2038 { typedef typename remove_reference<_Tp>::type* type; };
2039
2040 /// add_pointer
2041 template<typename _Tp>
2042 struct add_pointer
2043 : public __add_pointer_helper<_Tp>
2044 { };
2045
2046#if __cplusplus > 201103L
2047 /// Alias template for remove_pointer
2048 template<typename _Tp>
2049 using remove_pointer_t = typename remove_pointer<_Tp>::type;
2050
2051 /// Alias template for add_pointer
2052 template<typename _Tp>
2053 using add_pointer_t = typename add_pointer<_Tp>::type;
2054#endif
2055
2056 template<std::size_t _Len>
2057 struct __aligned_storage_msa
2058 {
2059 union __type
2060 {
2061 unsigned char __data[_Len];
2062 struct __attribute__((__aligned__)) { } __align;
2063 };
2064 };
2065
2066 /**
2067 * @brief Alignment type.
2068 *
2069 * The value of _Align is a default-alignment which shall be the
2070 * most stringent alignment requirement for any C++ object type
2071 * whose size is no greater than _Len (3.9). The member typedef
2072 * type shall be a POD type suitable for use as uninitialized
2073 * storage for any object whose size is at most _Len and whose
2074 * alignment is a divisor of _Align.
2075 */
2076 template<std::size_t _Len, std::size_t _Align =
2077 __alignof__(typename __aligned_storage_msa<_Len>::__type)>
2078 struct aligned_storage
2079 {
2080 union type
2081 {
2082 unsigned char __data[_Len];
2083 struct __attribute__((__aligned__((_Align)))) { } __align;
2084 };
2085 };
2086
2087 template <typename... _Types>
2088 struct __strictest_alignment
2089 {
2090 static const size_t _S_alignment = 0;
2091 static const size_t _S_size = 0;
2092 };
2093
2094 template <typename _Tp, typename... _Types>
2095 struct __strictest_alignment<_Tp, _Types...>
2096 {
2097 static const size_t _S_alignment =
2098 alignof(_Tp) > __strictest_alignment<_Types...>::_S_alignment
2099 ? alignof(_Tp) : __strictest_alignment<_Types...>::_S_alignment;
2100 static const size_t _S_size =
2101 sizeof(_Tp) > __strictest_alignment<_Types...>::_S_size
2102 ? sizeof(_Tp) : __strictest_alignment<_Types...>::_S_size;
2103 };
2104
2105 /**
2106 * @brief Provide aligned storage for types.
2107 *
2108 * [meta.trans.other]
2109 *
2110 * Provides aligned storage for any of the provided types of at
2111 * least size _Len.
2112 *
2113 * @see aligned_storage
2114 */
2115 template <size_t _Len, typename... _Types>
2116 struct aligned_union
2117 {
2118 private:
2119 static_assert(sizeof...(_Types) != 0, "At least one type is required");
2120
2121 using __strictest = __strictest_alignment<_Types...>;
2122 static const size_t _S_len = _Len > __strictest::_S_size
2123 ? _Len : __strictest::_S_size;
2124 public:
2125 /// The value of the strictest alignment of _Types.
2126 static const size_t alignment_value = __strictest::_S_alignment;
2127 /// The storage.
2128 typedef typename aligned_storage<_S_len, alignment_value>::type type;
2129 };
2130
2131 template <size_t _Len, typename... _Types>
2132 const size_t aligned_union<_Len, _Types...>::alignment_value;
2133
2134 /// @cond undocumented
2135
2136 // Decay trait for arrays and functions, used for perfect forwarding
2137 // in make_pair, make_tuple, etc.
2138 template<typename _Up,
2139 bool _IsArray = is_array<_Up>::value,
2140 bool _IsFunction = is_function<_Up>::value>
2141 struct __decay_selector;
2142
2143 // NB: DR 705.
2144 template<typename _Up>
2145 struct __decay_selector<_Up, false, false>
2146 { typedef __remove_cv_t<_Up> __type; };
2147
2148 template<typename _Up>
2149 struct __decay_selector<_Up, true, false>
2150 { typedef typename remove_extent<_Up>::type* __type; };
2151
2152 template<typename _Up>
2153 struct __decay_selector<_Up, false, true>
2154 { typedef typename add_pointer<_Up>::type __type; };
2155 /// @endcond
2156
2157 /// decay
2158 template<typename _Tp>
2159 class decay
2160 {
2161 typedef typename remove_reference<_Tp>::type __remove_type;
2162
2163 public:
2164 typedef typename __decay_selector<__remove_type>::__type type;
2165 };
2166
2167 /// @cond undocumented
2168
2169 // Helper which adds a reference to a type when given a reference_wrapper
2170 template<typename _Tp>
2171 struct __strip_reference_wrapper
2172 {
2173 typedef _Tp __type;
2174 };
2175
2176 template<typename _Tp>
2177 struct __strip_reference_wrapper<reference_wrapper<_Tp> >
2178 {
2179 typedef _Tp& __type;
2180 };
2181
2182 // __decay_t (std::decay_t for C++11).
2183 template<typename _Tp>
2184 using __decay_t = typename decay<_Tp>::type;
2185
2186 template<typename _Tp>
2187 using __decay_and_strip = __strip_reference_wrapper<__decay_t<_Tp>>;
2188 /// @endcond
2189
2190 // Primary template.
2191 /// Define a member typedef `type` only if a boolean constant is true.
2192 template<bool, typename _Tp = void>
2193 struct enable_if
2194 { };
2195
2196 // Partial specialization for true.
2197 template<typename _Tp>
2198 struct enable_if<true, _Tp>
2199 { typedef _Tp type; };
2200
2201 /// @cond undocumented
2202
2203 // __enable_if_t (std::enable_if_t for C++11)
2204 template<bool _Cond, typename _Tp = void>
2205 using __enable_if_t = typename enable_if<_Cond, _Tp>::type;
2206
2207 // Helper for SFINAE constraints
2208 template<typename... _Cond>
2209 using _Require = __enable_if_t<__and_<_Cond...>::value>;
2210
2211 // __remove_cvref_t (std::remove_cvref_t for C++11).
2212 template<typename _Tp>
2213 using __remove_cvref_t
2214 = typename remove_cv<typename remove_reference<_Tp>::type>::type;
2215 /// @endcond
2216
2217 // Primary template.
2218 /// Define a member typedef @c type to one of two argument types.
2219 template<bool _Cond, typename _Iftrue, typename _Iffalse>
2220 struct conditional
2221 { typedef _Iftrue type; };
2222
2223 // Partial specialization for false.
2224 template<typename _Iftrue, typename _Iffalse>
2225 struct conditional<false, _Iftrue, _Iffalse>
2226 { typedef _Iffalse type; };
2227
2228 /// common_type
2229 template<typename... _Tp>
2230 struct common_type;
2231
2232 // Sfinae-friendly common_type implementation:
2233
2234 /// @cond undocumented
2235 struct __do_common_type_impl
2236 {
2237 template<typename _Tp, typename _Up>
2238 using __cond_t
2239 = decltype(true ? std::declval<_Tp>() : std::declval<_Up>());
2240
2241 // if decay_t<decltype(false ? declval<D1>() : declval<D2>())>
2242 // denotes a valid type, let C denote that type.
2243 template<typename _Tp, typename _Up>
2244 static __success_type<__decay_t<__cond_t<_Tp, _Up>>>
2245 _S_test(int);
2246
2247#if __cplusplus > 201703L
2248 // Otherwise, if COND-RES(CREF(D1), CREF(D2)) denotes a type,
2249 // let C denote the type decay_t<COND-RES(CREF(D1), CREF(D2))>.
2250 template<typename _Tp, typename _Up>
2251 static __success_type<__remove_cvref_t<__cond_t<const _Tp&, const _Up&>>>
2252 _S_test_2(int);
2253#endif
2254
2255 template<typename, typename>
2256 static __failure_type
2257 _S_test_2(...);
2258
2259 template<typename _Tp, typename _Up>
2260 static decltype(_S_test_2<_Tp, _Up>(0))
2261 _S_test(...);
2262 };
2263
2264 // If sizeof...(T) is zero, there shall be no member type.
2265 template<>
2266 struct common_type<>
2267 { };
2268
2269 // If sizeof...(T) is one, the same type, if any, as common_type_t<T0, T0>.
2270 template<typename _Tp0>
2271 struct common_type<_Tp0>
2272 : public common_type<_Tp0, _Tp0>
2273 { };
2274
2275 // If sizeof...(T) is two, ...
2276 template<typename _Tp1, typename _Tp2,
2277 typename _Dp1 = __decay_t<_Tp1>, typename _Dp2 = __decay_t<_Tp2>>
2278 struct __common_type_impl
2279 {
2280 // If is_same_v<T1, D1> is false or is_same_v<T2, D2> is false,
2281 // let C denote the same type, if any, as common_type_t<D1, D2>.
2282 using type = common_type<_Dp1, _Dp2>;
2283 };
2284
2285 template<typename _Tp1, typename _Tp2>
2286 struct __common_type_impl<_Tp1, _Tp2, _Tp1, _Tp2>
2287 : private __do_common_type_impl
2288 {
2289 // Otherwise, if decay_t<decltype(false ? declval<D1>() : declval<D2>())>
2290 // denotes a valid type, let C denote that type.
2291 using type = decltype(_S_test<_Tp1, _Tp2>(0));
2292 };
2293
2294 // If sizeof...(T) is two, ...
2295 template<typename _Tp1, typename _Tp2>
2296 struct common_type<_Tp1, _Tp2>
2297 : public __common_type_impl<_Tp1, _Tp2>::type
2298 { };
2299
2300 template<typename...>
2301 struct __common_type_pack
2302 { };
2303
2304 template<typename, typename, typename = void>
2305 struct __common_type_fold;
2306
2307 // If sizeof...(T) is greater than two, ...
2308 template<typename _Tp1, typename _Tp2, typename... _Rp>
2309 struct common_type<_Tp1, _Tp2, _Rp...>
2310 : public __common_type_fold<common_type<_Tp1, _Tp2>,
2311 __common_type_pack<_Rp...>>
2312 { };
2313
2314 // Let C denote the same type, if any, as common_type_t<T1, T2>.
2315 // If there is such a type C, type shall denote the same type, if any,
2316 // as common_type_t<C, R...>.
2317 template<typename _CTp, typename... _Rp>
2318 struct __common_type_fold<_CTp, __common_type_pack<_Rp...>,
2319 __void_t<typename _CTp::type>>
2320 : public common_type<typename _CTp::type, _Rp...>
2321 { };
2322
2323 // Otherwise, there shall be no member type.
2324 template<typename _CTp, typename _Rp>
2325 struct __common_type_fold<_CTp, _Rp, void>
2326 { };
2327
2328 template<typename _Tp, bool = is_enum<_Tp>::value>
2329 struct __underlying_type_impl
2330 {
2331 using type = __underlying_type(_Tp);
2332 };
2333
2334 template<typename _Tp>
2335 struct __underlying_type_impl<_Tp, false>
2336 { };
2337 /// @endcond
2338
2339 /// The underlying type of an enum.
2340 template<typename _Tp>
2341 struct underlying_type
2342 : public __underlying_type_impl<_Tp>
2343 { };
2344
2345 /// @cond undocumented
2346 template<typename _Tp>
2347 struct __declval_protector
2348 {
2349 static const bool __stop = false;
2350 };
2351 /// @endcond
2352
2353 /** Utility to simplify expressions used in unevaluated operands
2354 * @since C++11
2355 * @ingroup utilities
2356 */
2357 template<typename _Tp>
2358 auto declval() noexcept -> decltype(__declval<_Tp>(0))
2359 {
2360 static_assert(__declval_protector<_Tp>::__stop,
2361 "declval() must not be used!");
2362 return __declval<_Tp>(0);
2363 }
2364
2365 /// result_of
2366 template<typename _Signature>
2367 struct result_of;
2368
2369 // Sfinae-friendly result_of implementation:
2370
2371#define __cpp_lib_result_of_sfinae 201210
2372
2373 /// @cond undocumented
2374 struct __invoke_memfun_ref { };
2375 struct __invoke_memfun_deref { };
2376 struct __invoke_memobj_ref { };
2377 struct __invoke_memobj_deref { };
2378 struct __invoke_other { };
2379
2380 // Associate a tag type with a specialization of __success_type.
2381 template<typename _Tp, typename _Tag>
2382 struct __result_of_success : __success_type<_Tp>
2383 { using __invoke_type = _Tag; };
2384
2385 // [func.require] paragraph 1 bullet 1:
2386 struct __result_of_memfun_ref_impl
2387 {
2388 template<typename _Fp, typename _Tp1, typename... _Args>
2389 static __result_of_success<decltype(
2390 (std::declval<_Tp1>().*std::declval<_Fp>())(std::declval<_Args>()...)
2391 ), __invoke_memfun_ref> _S_test(int);
2392
2393 template<typename...>
2394 static __failure_type _S_test(...);
2395 };
2396
2397 template<typename _MemPtr, typename _Arg, typename... _Args>
2398 struct __result_of_memfun_ref
2399 : private __result_of_memfun_ref_impl
2400 {
2401 typedef decltype(_S_test<_MemPtr, _Arg, _Args...>(0)) type;
2402 };
2403
2404 // [func.require] paragraph 1 bullet 2:
2405 struct __result_of_memfun_deref_impl
2406 {
2407 template<typename _Fp, typename _Tp1, typename... _Args>
2408 static __result_of_success<decltype(
2409 ((*std::declval<_Tp1>()).*std::declval<_Fp>())(std::declval<_Args>()...)
2410 ), __invoke_memfun_deref> _S_test(int);
2411
2412 template<typename...>
2413 static __failure_type _S_test(...);
2414 };
2415
2416 template<typename _MemPtr, typename _Arg, typename... _Args>
2417 struct __result_of_memfun_deref
2418 : private __result_of_memfun_deref_impl
2419 {
2420 typedef decltype(_S_test<_MemPtr, _Arg, _Args...>(0)) type;
2421 };
2422
2423 // [func.require] paragraph 1 bullet 3:
2424 struct __result_of_memobj_ref_impl
2425 {
2426 template<typename _Fp, typename _Tp1>
2427 static __result_of_success<decltype(
2428 std::declval<_Tp1>().*std::declval<_Fp>()
2429 ), __invoke_memobj_ref> _S_test(int);
2430
2431 template<typename, typename>
2432 static __failure_type _S_test(...);
2433 };
2434
2435 template<typename _MemPtr, typename _Arg>
2436 struct __result_of_memobj_ref
2437 : private __result_of_memobj_ref_impl
2438 {
2439 typedef decltype(_S_test<_MemPtr, _Arg>(0)) type;
2440 };
2441
2442 // [func.require] paragraph 1 bullet 4:
2443 struct __result_of_memobj_deref_impl
2444 {
2445 template<typename _Fp, typename _Tp1>
2446 static __result_of_success<decltype(
2447 (*std::declval<_Tp1>()).*std::declval<_Fp>()
2448 ), __invoke_memobj_deref> _S_test(int);
2449
2450 template<typename, typename>
2451 static __failure_type _S_test(...);
2452 };
2453
2454 template<typename _MemPtr, typename _Arg>
2455 struct __result_of_memobj_deref
2456 : private __result_of_memobj_deref_impl
2457 {
2458 typedef decltype(_S_test<_MemPtr, _Arg>(0)) type;
2459 };
2460
2461 template<typename _MemPtr, typename _Arg>
2462 struct __result_of_memobj;
2463
2464 template<typename _Res, typename _Class, typename _Arg>
2465 struct __result_of_memobj<_Res _Class::*, _Arg>
2466 {
2467 typedef __remove_cvref_t<_Arg> _Argval;
2468 typedef _Res _Class::* _MemPtr;
2469 typedef typename conditional<__or_<is_same<_Argval, _Class>,
2470 is_base_of<_Class, _Argval>>::value,
2471 __result_of_memobj_ref<_MemPtr, _Arg>,
2472 __result_of_memobj_deref<_MemPtr, _Arg>
2473 >::type::type type;
2474 };
2475
2476 template<typename _MemPtr, typename _Arg, typename... _Args>
2477 struct __result_of_memfun;
2478
2479 template<typename _Res, typename _Class, typename _Arg, typename... _Args>
2480 struct __result_of_memfun<_Res _Class::*, _Arg, _Args...>
2481 {
2482 typedef typename remove_reference<_Arg>::type _Argval;
2483 typedef _Res _Class::* _MemPtr;
2484 typedef typename conditional<is_base_of<_Class, _Argval>::value,
2485 __result_of_memfun_ref<_MemPtr, _Arg, _Args...>,
2486 __result_of_memfun_deref<_MemPtr, _Arg, _Args...>
2487 >::type::type type;
2488 };
2489
2490 // _GLIBCXX_RESOLVE_LIB_DEFECTS
2491 // 2219. INVOKE-ing a pointer to member with a reference_wrapper
2492 // as the object expression
2493
2494 // Used by result_of, invoke etc. to unwrap a reference_wrapper.
2495 template<typename _Tp, typename _Up = __remove_cvref_t<_Tp>>
2496 struct __inv_unwrap
2497 {
2498 using type = _Tp;
2499 };
2500
2501 template<typename _Tp, typename _Up>
2502 struct __inv_unwrap<_Tp, reference_wrapper<_Up>>
2503 {
2504 using type = _Up&;
2505 };
2506
2507 template<bool, bool, typename _Functor, typename... _ArgTypes>
2508 struct __result_of_impl
2509 {
2510 typedef __failure_type type;
2511 };
2512
2513 template<typename _MemPtr, typename _Arg>
2514 struct __result_of_impl<true, false, _MemPtr, _Arg>
2515 : public __result_of_memobj<__decay_t<_MemPtr>,
2516 typename __inv_unwrap<_Arg>::type>
2517 { };
2518
2519 template<typename _MemPtr, typename _Arg, typename... _Args>
2520 struct __result_of_impl<false, true, _MemPtr, _Arg, _Args...>
2521 : public __result_of_memfun<__decay_t<_MemPtr>,
2522 typename __inv_unwrap<_Arg>::type, _Args...>
2523 { };
2524
2525 // [func.require] paragraph 1 bullet 5:
2526 struct __result_of_other_impl
2527 {
2528 template<typename _Fn, typename... _Args>
2529 static __result_of_success<decltype(
2530 std::declval<_Fn>()(std::declval<_Args>()...)
2531 ), __invoke_other> _S_test(int);
2532
2533 template<typename...>
2534 static __failure_type _S_test(...);
2535 };
2536
2537 template<typename _Functor, typename... _ArgTypes>
2538 struct __result_of_impl<false, false, _Functor, _ArgTypes...>
2539 : private __result_of_other_impl
2540 {
2541 typedef decltype(_S_test<_Functor, _ArgTypes...>(0)) type;
2542 };
2543
2544 // __invoke_result (std::invoke_result for C++11)
2545 template<typename _Functor, typename... _ArgTypes>
2546 struct __invoke_result
2547 : public __result_of_impl<
2548 is_member_object_pointer<
2549 typename remove_reference<_Functor>::type
2550 >::value,
2551 is_member_function_pointer<
2552 typename remove_reference<_Functor>::type
2553 >::value,
2554 _Functor, _ArgTypes...
2555 >::type
2556 { };
2557 /// @endcond
2558
2559 template<typename _Functor, typename... _ArgTypes>
2560 struct result_of<_Functor(_ArgTypes...)>
2561 : public __invoke_result<_Functor, _ArgTypes...>
2562 { };
2563
2564#if __cplusplus >= 201402L
2565 /// Alias template for aligned_storage
2566 template<size_t _Len, size_t _Align =
2567 __alignof__(typename __aligned_storage_msa<_Len>::__type)>
2568 using aligned_storage_t = typename aligned_storage<_Len, _Align>::type;
2569
2570 template <size_t _Len, typename... _Types>
2571 using aligned_union_t = typename aligned_union<_Len, _Types...>::type;
2572
2573 /// Alias template for decay
2574 template<typename _Tp>
2575 using decay_t = typename decay<_Tp>::type;
2576
2577 /// Alias template for enable_if
2578 template<bool _Cond, typename _Tp = void>
2579 using enable_if_t = typename enable_if<_Cond, _Tp>::type;
2580
2581 /// Alias template for conditional
2582 template<bool _Cond, typename _Iftrue, typename _Iffalse>
2583 using conditional_t = typename conditional<_Cond, _Iftrue, _Iffalse>::type;
2584
2585 /// Alias template for common_type
2586 template<typename... _Tp>
2587 using common_type_t = typename common_type<_Tp...>::type;
2588
2589 /// Alias template for underlying_type
2590 template<typename _Tp>
2591 using underlying_type_t = typename underlying_type<_Tp>::type;
2592
2593 /// Alias template for result_of
2594 template<typename _Tp>
2595 using result_of_t = typename result_of<_Tp>::type;
2596#endif // C++14
2597
2598#if __cplusplus >= 201703L || !defined(__STRICT_ANSI__) // c++17 or gnu++11
2599#define __cpp_lib_void_t 201411
2600 /// A metafunction that always yields void, used for detecting valid types.
2601 template<typename...> using void_t = void;
2602#endif
2603
2604 /// @cond undocumented
2605
2606 /// Implementation of the detection idiom (negative case).
2607 template<typename _Default, typename _AlwaysVoid,
2608 template<typename...> class _Op, typename... _Args>
2609 struct __detector
2610 {
2611 using value_t = false_type;
2612 using type = _Default;
2613 };
2614
2615 /// Implementation of the detection idiom (positive case).
2616 template<typename _Default, template<typename...> class _Op,
2617 typename... _Args>
2618 struct __detector<_Default, __void_t<_Op<_Args...>>, _Op, _Args...>
2619 {
2620 using value_t = true_type;
2621 using type = _Op<_Args...>;
2622 };
2623
2624 // Detect whether _Op<_Args...> is a valid type, use _Default if not.
2625 template<typename _Default, template<typename...> class _Op,
2626 typename... _Args>
2627 using __detected_or = __detector<_Default, void, _Op, _Args...>;
2628
2629 // _Op<_Args...> if that is a valid type, otherwise _Default.
2630 template<typename _Default, template<typename...> class _Op,
2631 typename... _Args>
2632 using __detected_or_t
2633 = typename __detected_or<_Default, _Op, _Args...>::type;
2634
2635 /**
2636 * Use SFINAE to determine if the type _Tp has a publicly-accessible
2637 * member type _NTYPE.
2638 */
2639#define _GLIBCXX_HAS_NESTED_TYPE(_NTYPE) \
2640 template<typename _Tp, typename = __void_t<>> \
2641 struct __has_##_NTYPE \
2642 : false_type \
2643 { }; \
2644 template<typename _Tp> \
2645 struct __has_##_NTYPE<_Tp, __void_t<typename _Tp::_NTYPE>> \
2646 : true_type \
2647 { };
2648
2649 template <typename _Tp>
2650 struct __is_swappable;
2651
2652 template <typename _Tp>
2653 struct __is_nothrow_swappable;
2654
2655 template<typename>
2656 struct __is_tuple_like_impl : false_type
2657 { };
2658
2659 template<typename... _Tps>
2660 struct __is_tuple_like_impl<tuple<_Tps...>> : true_type
2661 { };
2662
2663 // Internal type trait that allows us to sfinae-protect tuple_cat.
2664 template<typename _Tp>
2665 struct __is_tuple_like
2666 : public __is_tuple_like_impl<__remove_cvref_t<_Tp>>::type
2667 { };
2668 /// @endcond
2669
2670 template<typename _Tp>
2671 _GLIBCXX20_CONSTEXPR
2672 inline
2673 _Require<__not_<__is_tuple_like<_Tp>>,
2674 is_move_constructible<_Tp>,
2675 is_move_assignable<_Tp>>
2676 swap(_Tp&, _Tp&)
2677 noexcept(__and_<is_nothrow_move_constructible<_Tp>,
2678 is_nothrow_move_assignable<_Tp>>::value);
2679
2680 template<typename _Tp, size_t _Nm>
2681 _GLIBCXX20_CONSTEXPR
2682 inline
2683 __enable_if_t<__is_swappable<_Tp>::value>
2684 swap(_Tp (&__a)[_Nm], _Tp (&__b)[_Nm])
2685 noexcept(__is_nothrow_swappable<_Tp>::value);
2686
2687 /// @cond undocumented
2688 namespace __swappable_details {
2689 using std::swap;
2690
2691 struct __do_is_swappable_impl
2692 {
2693 template<typename _Tp, typename
2694 = decltype(swap(std::declval<_Tp&>(), std::declval<_Tp&>()))>
2695 static true_type __test(int);
2696
2697 template<typename>
2698 static false_type __test(...);
2699 };
2700
2701 struct __do_is_nothrow_swappable_impl
2702 {
2703 template<typename _Tp>
2704 static __bool_constant<
2705 noexcept(swap(std::declval<_Tp&>(), std::declval<_Tp&>()))
2706 > __test(int);
2707
2708 template<typename>
2709 static false_type __test(...);
2710 };
2711
2712 } // namespace __swappable_details
2713
2714 template<typename _Tp>
2715 struct __is_swappable_impl
2716 : public __swappable_details::__do_is_swappable_impl
2717 {
2718 typedef decltype(__test<_Tp>(0)) type;
2719 };
2720
2721 template<typename _Tp>
2722 struct __is_nothrow_swappable_impl
2723 : public __swappable_details::__do_is_nothrow_swappable_impl
2724 {
2725 typedef decltype(__test<_Tp>(0)) type;
2726 };
2727
2728 template<typename _Tp>
2729 struct __is_swappable
2730 : public __is_swappable_impl<_Tp>::type
2731 { };
2732
2733 template<typename _Tp>
2734 struct __is_nothrow_swappable
2735 : public __is_nothrow_swappable_impl<_Tp>::type
2736 { };
2737 /// @endcond
2738
2739#if __cplusplus > 201402L || !defined(__STRICT_ANSI__) // c++1z or gnu++11
2740#define __cpp_lib_is_swappable 201603
2741 /// Metafunctions used for detecting swappable types: p0185r1
2742
2743 /// is_swappable
2744 template<typename _Tp>
2745 struct is_swappable
2746 : public __is_swappable_impl<_Tp>::type
2747 {
2748 static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
2749 "template argument must be a complete class or an unbounded array");
2750 };
2751
2752 /// is_nothrow_swappable
2753 template<typename _Tp>
2754 struct is_nothrow_swappable
2755 : public __is_nothrow_swappable_impl<_Tp>::type
2756 {
2757 static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
2758 "template argument must be a complete class or an unbounded array");
2759 };
2760
2761#if __cplusplus >= 201402L
2762 /// is_swappable_v
2763 template<typename _Tp>
2764 _GLIBCXX17_INLINE constexpr bool is_swappable_v =
2765 is_swappable<_Tp>::value;
2766
2767 /// is_nothrow_swappable_v
2768 template<typename _Tp>
2769 _GLIBCXX17_INLINE constexpr bool is_nothrow_swappable_v =
2770 is_nothrow_swappable<_Tp>::value;
2771#endif // __cplusplus >= 201402L
2772
2773 /// @cond undocumented
2774 namespace __swappable_with_details {
2775 using std::swap;
2776
2777 struct __do_is_swappable_with_impl
2778 {
2779 template<typename _Tp, typename _Up, typename
2780 = decltype(swap(std::declval<_Tp>(), std::declval<_Up>())),
2781 typename
2782 = decltype(swap(std::declval<_Up>(), std::declval<_Tp>()))>
2783 static true_type __test(int);
2784
2785 template<typename, typename>
2786 static false_type __test(...);
2787 };
2788
2789 struct __do_is_nothrow_swappable_with_impl
2790 {
2791 template<typename _Tp, typename _Up>
2792 static __bool_constant<
2793 noexcept(swap(std::declval<_Tp>(), std::declval<_Up>()))
2794 &&
2795 noexcept(swap(std::declval<_Up>(), std::declval<_Tp>()))
2796 > __test(int);
2797
2798 template<typename, typename>
2799 static false_type __test(...);
2800 };
2801
2802 } // namespace __swappable_with_details
2803
2804 template<typename _Tp, typename _Up>
2805 struct __is_swappable_with_impl
2806 : public __swappable_with_details::__do_is_swappable_with_impl
2807 {
2808 typedef decltype(__test<_Tp, _Up>(0)) type;
2809 };
2810
2811 // Optimization for the homogenous lvalue case, not required:
2812 template<typename _Tp>
2813 struct __is_swappable_with_impl<_Tp&, _Tp&>
2814 : public __swappable_details::__do_is_swappable_impl
2815 {
2816 typedef decltype(__test<_Tp&>(0)) type;
2817 };
2818
2819 template<typename _Tp, typename _Up>
2820 struct __is_nothrow_swappable_with_impl
2821 : public __swappable_with_details::__do_is_nothrow_swappable_with_impl
2822 {
2823 typedef decltype(__test<_Tp, _Up>(0)) type;
2824 };
2825
2826 // Optimization for the homogenous lvalue case, not required:
2827 template<typename _Tp>
2828 struct __is_nothrow_swappable_with_impl<_Tp&, _Tp&>
2829 : public __swappable_details::__do_is_nothrow_swappable_impl
2830 {
2831 typedef decltype(__test<_Tp&>(0)) type;
2832 };
2833 /// @endcond
2834
2835 /// is_swappable_with
2836 template<typename _Tp, typename _Up>
2837 struct is_swappable_with
2838 : public __is_swappable_with_impl<_Tp, _Up>::type
2839 {
2840 static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
2841 "first template argument must be a complete class or an unbounded array");
2842 static_assert(std::__is_complete_or_unbounded(__type_identity<_Up>{}),
2843 "second template argument must be a complete class or an unbounded array");
2844 };
2845
2846 /// is_nothrow_swappable_with
2847 template<typename _Tp, typename _Up>
2848 struct is_nothrow_swappable_with
2849 : public __is_nothrow_swappable_with_impl<_Tp, _Up>::type
2850 {
2851 static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
2852 "first template argument must be a complete class or an unbounded array");
2853 static_assert(std::__is_complete_or_unbounded(__type_identity<_Up>{}),
2854 "second template argument must be a complete class or an unbounded array");
2855 };
2856
2857#if __cplusplus >= 201402L
2858 /// is_swappable_with_v
2859 template<typename _Tp, typename _Up>
2860 _GLIBCXX17_INLINE constexpr bool is_swappable_with_v =
2861 is_swappable_with<_Tp, _Up>::value;
2862
2863 /// is_nothrow_swappable_with_v
2864 template<typename _Tp, typename _Up>
2865 _GLIBCXX17_INLINE constexpr bool is_nothrow_swappable_with_v =
2866 is_nothrow_swappable_with<_Tp, _Up>::value;
2867#endif // __cplusplus >= 201402L
2868
2869#endif// c++1z or gnu++11
2870
2871 /// @cond undocumented
2872
2873 // __is_invocable (std::is_invocable for C++11)
2874
2875 // The primary template is used for invalid INVOKE expressions.
2876 template<typename _Result, typename _Ret,
2877 bool = is_void<_Ret>::value, typename = void>
2878 struct __is_invocable_impl
2879 : false_type
2880 {
2881 using __nothrow_type = false_type; // For is_nothrow_invocable_r
2882 };
2883
2884 // Used for valid INVOKE and INVOKE<void> expressions.
2885 template<typename _Result, typename _Ret>
2886 struct __is_invocable_impl<_Result, _Ret,
2887 /* is_void<_Ret> = */ true,
2888 __void_t<typename _Result::type>>
2889 : true_type
2890 {
2891 using __nothrow_type = true_type; // For is_nothrow_invocable_r
2892 };
2893
2894#pragma GCC diagnostic push
2895#pragma GCC diagnostic ignored "-Wctor-dtor-privacy"
2896 // Used for INVOKE<R> expressions to check the implicit conversion to R.
2897 template<typename _Result, typename _Ret>
2898 struct __is_invocable_impl<_Result, _Ret,
2899 /* is_void<_Ret> = */ false,
2900 __void_t<typename _Result::type>>
2901 {
2902 private:
2903 // The type of the INVOKE expression.
2904 // Unlike declval, this doesn't add_rvalue_reference, so it respects
2905 // guaranteed copy elision.
2906 static typename _Result::type _S_get() noexcept;
2907
2908 template<typename _Tp>
2909 static void _S_conv(_Tp) noexcept;
2910
2911 // This overload is viable if INVOKE(f, args...) can convert to _Tp.
2912 template<typename _Tp, bool _Check_Noex = false,
2913 typename = decltype(_S_conv<_Tp>(_S_get())),
2914 bool _Noex = noexcept(_S_conv<_Tp>(_S_get()))>
2915 static __bool_constant<_Check_Noex ? _Noex : true>
2916 _S_test(int);
2917
2918 template<typename _Tp, bool = false>
2919 static false_type
2920 _S_test(...);
2921
2922 public:
2923 // For is_invocable_r
2924 using type = decltype(_S_test<_Ret>(1));
2925
2926 // For is_nothrow_invocable_r
2927 using __nothrow_type = decltype(_S_test<_Ret, true>(1));
2928 };
2929#pragma GCC diagnostic pop
2930
2931 template<typename _Fn, typename... _ArgTypes>
2932 struct __is_invocable
2933 : __is_invocable_impl<__invoke_result<_Fn, _ArgTypes...>, void>::type
2934 { };
2935
2936 template<typename _Fn, typename _Tp, typename... _Args>
2937 constexpr bool __call_is_nt(__invoke_memfun_ref)
2938 {
2939 using _Up = typename __inv_unwrap<_Tp>::type;
2940 return noexcept((std::declval<_Up>().*std::declval<_Fn>())(
2941 std::declval<_Args>()...));
2942 }
2943
2944 template<typename _Fn, typename _Tp, typename... _Args>
2945 constexpr bool __call_is_nt(__invoke_memfun_deref)
2946 {
2947 return noexcept(((*std::declval<_Tp>()).*std::declval<_Fn>())(
2948 std::declval<_Args>()...));
2949 }
2950
2951 template<typename _Fn, typename _Tp>
2952 constexpr bool __call_is_nt(__invoke_memobj_ref)
2953 {
2954 using _Up = typename __inv_unwrap<_Tp>::type;
2955 return noexcept(std::declval<_Up>().*std::declval<_Fn>());
2956 }
2957
2958 template<typename _Fn, typename _Tp>
2959 constexpr bool __call_is_nt(__invoke_memobj_deref)
2960 {
2961 return noexcept((*std::declval<_Tp>()).*std::declval<_Fn>());
2962 }
2963
2964 template<typename _Fn, typename... _Args>
2965 constexpr bool __call_is_nt(__invoke_other)
2966 {
2967 return noexcept(std::declval<_Fn>()(std::declval<_Args>()...));
2968 }
2969
2970 template<typename _Result, typename _Fn, typename... _Args>
2971 struct __call_is_nothrow
2972 : __bool_constant<
2973 std::__call_is_nt<_Fn, _Args...>(typename _Result::__invoke_type{})
2974 >
2975 { };
2976
2977 template<typename _Fn, typename... _Args>
2978 using __call_is_nothrow_
2979 = __call_is_nothrow<__invoke_result<_Fn, _Args...>, _Fn, _Args...>;
2980
2981 // __is_nothrow_invocable (std::is_nothrow_invocable for C++11)
2982 template<typename _Fn, typename... _Args>
2983 struct __is_nothrow_invocable
2984 : __and_<__is_invocable<_Fn, _Args...>,
2985 __call_is_nothrow_<_Fn, _Args...>>::type
2986 { };
2987
2988#pragma GCC diagnostic push
2989#pragma GCC diagnostic ignored "-Wctor-dtor-privacy"
2990 struct __nonesuchbase {};
2991 struct __nonesuch : private __nonesuchbase {
2992 ~__nonesuch() = delete;
2993 __nonesuch(__nonesuch const&) = delete;
2994 void operator=(__nonesuch const&) = delete;
2995 };
2996#pragma GCC diagnostic pop
2997 /// @endcond
2998
2999#if __cplusplus >= 201703L
3000# define __cpp_lib_is_invocable 201703
3001
3002 /// std::invoke_result
3003 template<typename _Functor, typename... _ArgTypes>
3004 struct invoke_result
3005 : public __invoke_result<_Functor, _ArgTypes...>
3006 {
3007 static_assert(std::__is_complete_or_unbounded(__type_identity<_Functor>{}),
3008 "_Functor must be a complete class or an unbounded array");
3009 static_assert((std::__is_complete_or_unbounded(
3010 __type_identity<_ArgTypes>{}) && ...),
3011 "each argument type must be a complete class or an unbounded array");
3012 };
3013
3014 /// std::invoke_result_t
3015 template<typename _Fn, typename... _Args>
3016 using invoke_result_t = typename invoke_result<_Fn, _Args...>::type;
3017
3018 /// std::is_invocable
3019 template<typename _Fn, typename... _ArgTypes>
3020 struct is_invocable
3021 : __is_invocable_impl<__invoke_result<_Fn, _ArgTypes...>, void>::type
3022 {
3023 static_assert(std::__is_complete_or_unbounded(__type_identity<_Fn>{}),
3024 "_Fn must be a complete class or an unbounded array");
3025 static_assert((std::__is_complete_or_unbounded(
3026 __type_identity<_ArgTypes>{}) && ...),
3027 "each argument type must be a complete class or an unbounded array");
3028 };
3029
3030 /// std::is_invocable_r
3031 template<typename _Ret, typename _Fn, typename... _ArgTypes>
3032 struct is_invocable_r
3033 : __is_invocable_impl<__invoke_result<_Fn, _ArgTypes...>, _Ret>::type
3034 {
3035 static_assert(std::__is_complete_or_unbounded(__type_identity<_Fn>{}),
3036 "_Fn must be a complete class or an unbounded array");
3037 static_assert((std::__is_complete_or_unbounded(
3038 __type_identity<_ArgTypes>{}) && ...),
3039 "each argument type must be a complete class or an unbounded array");
3040 static_assert(std::__is_complete_or_unbounded(__type_identity<_Ret>{}),
3041 "_Ret must be a complete class or an unbounded array");
3042 };
3043
3044 /// std::is_nothrow_invocable
3045 template<typename _Fn, typename... _ArgTypes>
3046 struct is_nothrow_invocable
3047 : __and_<__is_invocable_impl<__invoke_result<_Fn, _ArgTypes...>, void>,
3048 __call_is_nothrow_<_Fn, _ArgTypes...>>::type
3049 {
3050 static_assert(std::__is_complete_or_unbounded(__type_identity<_Fn>{}),
3051 "_Fn must be a complete class or an unbounded array");
3052 static_assert((std::__is_complete_or_unbounded(
3053 __type_identity<_ArgTypes>{}) && ...),
3054 "each argument type must be a complete class or an unbounded array");
3055 };
3056
3057 /// @cond undocumented
3058 template<typename _Result, typename _Ret>
3059 using __is_nt_invocable_impl
3060 = typename __is_invocable_impl<_Result, _Ret>::__nothrow_type;
3061 /// @endcond
3062
3063 /// std::is_nothrow_invocable_r
3064 template<typename _Ret, typename _Fn, typename... _ArgTypes>
3065 struct is_nothrow_invocable_r
3066 : __and_<__is_nt_invocable_impl<__invoke_result<_Fn, _ArgTypes...>, _Ret>,
3067 __call_is_nothrow_<_Fn, _ArgTypes...>>::type
3068 {
3069 static_assert(std::__is_complete_or_unbounded(__type_identity<_Fn>{}),
3070 "_Fn must be a complete class or an unbounded array");
3071 static_assert((std::__is_complete_or_unbounded(
3072 __type_identity<_ArgTypes>{}) && ...),
3073 "each argument type must be a complete class or an unbounded array");
3074 static_assert(std::__is_complete_or_unbounded(__type_identity<_Ret>{}),
3075 "_Ret must be a complete class or an unbounded array");
3076 };
3077#endif // C++17
3078
3079#if __cplusplus >= 201703L
3080# define __cpp_lib_type_trait_variable_templates 201510L
3081 /**
3082 * @defgroup variable_templates Variable templates for type traits.
3083 * @ingroup metaprogramming
3084 *
3085 * The variable `is_foo_v<T>` is a boolean constant with the same value
3086 * as the type trait `is_foo<T>::value`.
3087 *
3088 * @since C++17
3089 */
3090
3091 /** @ingroup variable_templates
3092 * @{
3093 */
3094template <typename _Tp>
3095 inline constexpr bool is_void_v = is_void<_Tp>::value;
3096template <typename _Tp>
3097 inline constexpr bool is_null_pointer_v = is_null_pointer<_Tp>::value;
3098template <typename _Tp>
3099 inline constexpr bool is_integral_v = is_integral<_Tp>::value;
3100template <typename _Tp>
3101 inline constexpr bool is_floating_point_v = is_floating_point<_Tp>::value;
3102template <typename _Tp>
3103 inline constexpr bool is_array_v = is_array<_Tp>::value;
3104template <typename _Tp>
3105 inline constexpr bool is_pointer_v = is_pointer<_Tp>::value;
3106template <typename _Tp>
3107 inline constexpr bool is_lvalue_reference_v =
3108 is_lvalue_reference<_Tp>::value;
3109template <typename _Tp>
3110 inline constexpr bool is_rvalue_reference_v =
3111 is_rvalue_reference<_Tp>::value;
3112template <typename _Tp>
3113 inline constexpr bool is_member_object_pointer_v =
3114 is_member_object_pointer<_Tp>::value;
3115template <typename _Tp>
3116 inline constexpr bool is_member_function_pointer_v =
3117 is_member_function_pointer<_Tp>::value;
3118template <typename _Tp>
3119 inline constexpr bool is_enum_v = is_enum<_Tp>::value;
3120template <typename _Tp>
3121 inline constexpr bool is_union_v = is_union<_Tp>::value;
3122template <typename _Tp>
3123 inline constexpr bool is_class_v = is_class<_Tp>::value;
3124template <typename _Tp>
3125 inline constexpr bool is_function_v = is_function<_Tp>::value;
3126template <typename _Tp>
3127 inline constexpr bool is_reference_v = is_reference<_Tp>::value;
3128template <typename _Tp>
3129 inline constexpr bool is_arithmetic_v = is_arithmetic<_Tp>::value;
3130template <typename _Tp>
3131 inline constexpr bool is_fundamental_v = is_fundamental<_Tp>::value;
3132template <typename _Tp>
3133 inline constexpr bool is_object_v = is_object<_Tp>::value;
3134template <typename _Tp>
3135 inline constexpr bool is_scalar_v = is_scalar<_Tp>::value;
3136template <typename _Tp>
3137 inline constexpr bool is_compound_v = is_compound<_Tp>::value;
3138template <typename _Tp>
3139 inline constexpr bool is_member_pointer_v = is_member_pointer<_Tp>::value;
3140template <typename _Tp>
3141 inline constexpr bool is_const_v = is_const<_Tp>::value;
3142template <typename _Tp>
3143 inline constexpr bool is_volatile_v = is_volatile<_Tp>::value;
3144template <typename _Tp>
3145 inline constexpr bool is_trivial_v = is_trivial<_Tp>::value;
3146template <typename _Tp>
3147 inline constexpr bool is_trivially_copyable_v =
3148 is_trivially_copyable<_Tp>::value;
3149template <typename _Tp>
3150 inline constexpr bool is_standard_layout_v = is_standard_layout<_Tp>::value;
3151#pragma GCC diagnostic push
3152#pragma GCC diagnostic ignored "-Wdeprecated-declarations"
3153template <typename _Tp>
3154 _GLIBCXX20_DEPRECATED("use is_standard_layout_v && is_trivial_v instead")
3155 inline constexpr bool is_pod_v = is_pod<_Tp>::value;
3156template <typename _Tp>
3157 _GLIBCXX17_DEPRECATED
3158 inline constexpr bool is_literal_type_v = is_literal_type<_Tp>::value;
3159#pragma GCC diagnostic pop
3160 template <typename _Tp>
3161 inline constexpr bool is_empty_v = is_empty<_Tp>::value;
3162template <typename _Tp>
3163 inline constexpr bool is_polymorphic_v = is_polymorphic<_Tp>::value;
3164template <typename _Tp>
3165 inline constexpr bool is_abstract_v = is_abstract<_Tp>::value;
3166template <typename _Tp>
3167 inline constexpr bool is_final_v = is_final<_Tp>::value;
3168template <typename _Tp>
3169 inline constexpr bool is_signed_v = is_signed<_Tp>::value;
3170template <typename _Tp>
3171 inline constexpr bool is_unsigned_v = is_unsigned<_Tp>::value;
3172template <typename _Tp, typename... _Args>
3173 inline constexpr bool is_constructible_v =
3174 is_constructible<_Tp, _Args...>::value;
3175template <typename _Tp>
3176 inline constexpr bool is_default_constructible_v =
3177 is_default_constructible<_Tp>::value;
3178template <typename _Tp>
3179 inline constexpr bool is_copy_constructible_v =
3180 is_copy_constructible<_Tp>::value;
3181template <typename _Tp>
3182 inline constexpr bool is_move_constructible_v =
3183 is_move_constructible<_Tp>::value;
3184template <typename _Tp, typename _Up>
3185 inline constexpr bool is_assignable_v = is_assignable<_Tp, _Up>::value;
3186template <typename _Tp>
3187 inline constexpr bool is_copy_assignable_v = is_copy_assignable<_Tp>::value;
3188template <typename _Tp>
3189 inline constexpr bool is_move_assignable_v = is_move_assignable<_Tp>::value;
3190template <typename _Tp>
3191 inline constexpr bool is_destructible_v = is_destructible<_Tp>::value;
3192template <typename _Tp, typename... _Args>
3193 inline constexpr bool is_trivially_constructible_v =
3194 is_trivially_constructible<_Tp, _Args...>::value;
3195template <typename _Tp>
3196 inline constexpr bool is_trivially_default_constructible_v =
3197 is_trivially_default_constructible<_Tp>::value;
3198template <typename _Tp>
3199 inline constexpr bool is_trivially_copy_constructible_v =
3200 is_trivially_copy_constructible<_Tp>::value;
3201template <typename _Tp>
3202 inline constexpr bool is_trivially_move_constructible_v =
3203 is_trivially_move_constructible<_Tp>::value;
3204template <typename _Tp, typename _Up>
3205 inline constexpr bool is_trivially_assignable_v =
3206 is_trivially_assignable<_Tp, _Up>::value;
3207template <typename _Tp>
3208 inline constexpr bool is_trivially_copy_assignable_v =
3209 is_trivially_copy_assignable<_Tp>::value;
3210template <typename _Tp>
3211 inline constexpr bool is_trivially_move_assignable_v =
3212 is_trivially_move_assignable<_Tp>::value;
3213template <typename _Tp>
3214 inline constexpr bool is_trivially_destructible_v =
3215 is_trivially_destructible<_Tp>::value;
3216template <typename _Tp, typename... _Args>
3217 inline constexpr bool is_nothrow_constructible_v =
3218 is_nothrow_constructible<_Tp, _Args...>::value;
3219template <typename _Tp>
3220 inline constexpr bool is_nothrow_default_constructible_v =
3221 is_nothrow_default_constructible<_Tp>::value;
3222template <typename _Tp>
3223 inline constexpr bool is_nothrow_copy_constructible_v =
3224 is_nothrow_copy_constructible<_Tp>::value;
3225template <typename _Tp>
3226 inline constexpr bool is_nothrow_move_constructible_v =
3227 is_nothrow_move_constructible<_Tp>::value;
3228template <typename _Tp, typename _Up>
3229 inline constexpr bool is_nothrow_assignable_v =
3230 is_nothrow_assignable<_Tp, _Up>::value;
3231template <typename _Tp>
3232 inline constexpr bool is_nothrow_copy_assignable_v =
3233 is_nothrow_copy_assignable<_Tp>::value;
3234template <typename _Tp>
3235 inline constexpr bool is_nothrow_move_assignable_v =
3236 is_nothrow_move_assignable<_Tp>::value;
3237template <typename _Tp>
3238 inline constexpr bool is_nothrow_destructible_v =
3239 is_nothrow_destructible<_Tp>::value;
3240template <typename _Tp>
3241 inline constexpr bool has_virtual_destructor_v =
3242 has_virtual_destructor<_Tp>::value;
3243template <typename _Tp>
3244 inline constexpr size_t alignment_of_v = alignment_of<_Tp>::value;
3245template <typename _Tp>
3246 inline constexpr size_t rank_v = rank<_Tp>::value;
3247template <typename _Tp, unsigned _Idx = 0>
3248 inline constexpr size_t extent_v = extent<_Tp, _Idx>::value;
3249#ifdef _GLIBCXX_HAVE_BUILTIN_IS_SAME
3250template <typename _Tp, typename _Up>
3251 inline constexpr bool is_same_v = __is_same(_Tp, _Up);
3252#else
3253template <typename _Tp, typename _Up>
3254 inline constexpr bool is_same_v = std::is_same<_Tp, _Up>::value;
3255#endif
3256template <typename _Base, typename _Derived>
3257 inline constexpr bool is_base_of_v = is_base_of<_Base, _Derived>::value;
3258template <typename _From, typename _To>
3259 inline constexpr bool is_convertible_v = is_convertible<_From, _To>::value;
3260template<typename _Fn, typename... _Args>
3261 inline constexpr bool is_invocable_v = is_invocable<_Fn, _Args...>::value;
3262template<typename _Fn, typename... _Args>
3263 inline constexpr bool is_nothrow_invocable_v
3264 = is_nothrow_invocable<_Fn, _Args...>::value;
3265template<typename _Ret, typename _Fn, typename... _Args>
3266 inline constexpr bool is_invocable_r_v
3267 = is_invocable_r<_Ret, _Fn, _Args...>::value;
3268template<typename _Ret, typename _Fn, typename... _Args>
3269 inline constexpr bool is_nothrow_invocable_r_v
3270 = is_nothrow_invocable_r<_Ret, _Fn, _Args...>::value;
3271/// @}
3272
3273#ifdef _GLIBCXX_HAVE_BUILTIN_HAS_UNIQ_OBJ_REP
3274# define __cpp_lib_has_unique_object_representations 201606
3275 /// has_unique_object_representations
3276 template<typename _Tp>
3277 struct has_unique_object_representations
3278 : bool_constant<__has_unique_object_representations(
3279 remove_cv_t<remove_all_extents_t<_Tp>>
3280 )>
3281 {
3282 static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
3283 "template argument must be a complete class or an unbounded array");
3284 };
3285
3286 /// @ingroup variable_templates
3287 template<typename _Tp>
3288 inline constexpr bool has_unique_object_representations_v
3289 = has_unique_object_representations<_Tp>::value;
3290#endif
3291
3292#ifdef _GLIBCXX_HAVE_BUILTIN_IS_AGGREGATE
3293# define __cpp_lib_is_aggregate 201703
3294 /// is_aggregate
3295 template<typename _Tp>
3296 struct is_aggregate
3297 : bool_constant<__is_aggregate(remove_cv_t<_Tp>)>
3298 { };
3299
3300 /// @ingroup variable_templates
3301 template<typename _Tp>
3302 inline constexpr bool is_aggregate_v = is_aggregate<_Tp>::value;
3303#endif
3304#endif // C++17
3305
3306#if __cplusplus > 201703L
3307#define __cpp_lib_remove_cvref 201711L
3308
3309 /// Remove references and cv-qualifiers.
3310 template<typename _Tp>
3311 struct remove_cvref
3312 : remove_cv<_Tp>
3313 { };
3314
3315 template<typename _Tp>
3316 struct remove_cvref<_Tp&>
3317 : remove_cv<_Tp>
3318 { };
3319
3320 template<typename _Tp>
3321 struct remove_cvref<_Tp&&>
3322 : remove_cv<_Tp>
3323 { };
3324
3325 template<typename _Tp>
3326 using remove_cvref_t = typename remove_cvref<_Tp>::type;
3327
3328#define __cpp_lib_type_identity 201806L
3329 /// Identity metafunction.
3330 template<typename _Tp>
3331 struct type_identity { using type = _Tp; };
3332
3333 template<typename _Tp>
3334 using type_identity_t = typename type_identity<_Tp>::type;
3335
3336#define __cpp_lib_unwrap_ref 201811L
3337
3338 /// Unwrap a reference_wrapper
3339 template<typename _Tp>
3340 struct unwrap_reference { using type = _Tp; };
3341
3342 template<typename _Tp>
3343 struct unwrap_reference<reference_wrapper<_Tp>> { using type = _Tp&; };
3344
3345 template<typename _Tp>
3346 using unwrap_reference_t = typename unwrap_reference<_Tp>::type;
3347
3348 /// Decay type and if it's a reference_wrapper, unwrap it
3349 template<typename _Tp>
3350 struct unwrap_ref_decay { using type = unwrap_reference_t<decay_t<_Tp>>; };
3351
3352 template<typename _Tp>
3353 using unwrap_ref_decay_t = typename unwrap_ref_decay<_Tp>::type;
3354
3355#define __cpp_lib_bounded_array_traits 201902L
3356
3357 /// True for a type that is an array of known bound.
3358 template<typename _Tp>
3359 struct is_bounded_array
3360 : public __is_array_known_bounds<_Tp>
3361 { };
3362
3363 /// True for a type that is an array of unknown bound.
3364 template<typename _Tp>
3365 struct is_unbounded_array
3366 : public __is_array_unknown_bounds<_Tp>
3367 { };
3368
3369 /// @ingroup variable_templates
3370 template<typename _Tp>
3371 inline constexpr bool is_bounded_array_v
3372 = is_bounded_array<_Tp>::value;
3373
3374 /// @ingroup variable_templates
3375 template<typename _Tp>
3376 inline constexpr bool is_unbounded_array_v
3377 = is_unbounded_array<_Tp>::value;
3378
3379#if __cplusplus > 202002L
3380#define __cpp_lib_is_scoped_enum 202011L
3381
3382 /// @since C++23
3383 //@{
3384
3385 template<typename _Tp>
3386 struct is_scoped_enum
3387 : false_type
3388 { };
3389
3390 template<typename _Tp>
3391 requires __is_enum(_Tp)
3392 && requires(_Tp __t) { __t = __t; } // fails if incomplete
3393 struct is_scoped_enum<_Tp>
3394 : bool_constant<!requires(_Tp __t, void(*__f)(int)) { __f(__t); }>
3395 { };
3396
3397 // FIXME remove this partial specialization and use remove_cv_t<_Tp> above
3398 // when PR c++/99968 is fixed.
3399 template<typename _Tp>
3400 requires __is_enum(_Tp)
3401 && requires(_Tp __t) { __t = __t; } // fails if incomplete
3402 struct is_scoped_enum<const _Tp>
3403 : bool_constant<!requires(_Tp __t, void(*__f)(int)) { __f(__t); }>
3404 { };
3405
3406 /**
3407 * @ingroup variable_templates
3408 */
3409 template<typename _Tp>
3410 inline constexpr bool is_scoped_enum_v = is_scoped_enum<_Tp>::value;
3411#endif // C++23
3412
3413#ifdef _GLIBCXX_HAVE_BUILTIN_IS_CONSTANT_EVALUATED
3414
3415#define __cpp_lib_is_constant_evaluated 201811L
3416
3417 /// Returns true only when called during constant evaluation.
3418 constexpr inline bool
3419 is_constant_evaluated() noexcept
3420 { return __builtin_is_constant_evaluated(); }
3421 /// @}
3422#endif
3423
3424 /// @cond undocumented
3425 template<typename _From, typename _To>
3426 using __copy_cv = typename __match_cv_qualifiers<_From, _To>::__type;
3427
3428 template<typename _Xp, typename _Yp>
3429 using __cond_res
3430 = decltype(false ? declval<_Xp(&)()>()() : declval<_Yp(&)()>()());
3431
3432 template<typename _Ap, typename _Bp, typename = void>
3433 struct __common_ref_impl
3434 { };
3435
3436 // [meta.trans.other], COMMON-REF(A, B)
3437 template<typename _Ap, typename _Bp>
3438 using __common_ref = typename __common_ref_impl<_Ap, _Bp>::type;
3439
3440 // COND-RES(COPYCV(X, Y) &, COPYCV(Y, X) &)
3441 template<typename _Xp, typename _Yp>
3442 using __condres_cvref
3443 = __cond_res<__copy_cv<_Xp, _Yp>&, __copy_cv<_Yp, _Xp>&>;
3444
3445 // If A and B are both lvalue reference types, ...
3446 template<typename _Xp, typename _Yp>
3447 struct __common_ref_impl<_Xp&, _Yp&, __void_t<__condres_cvref<_Xp, _Yp>>>
3448 : enable_if<is_reference_v<__condres_cvref<_Xp, _Yp>>,
3449 __condres_cvref<_Xp, _Yp>>
3450 { };
3451
3452 // let C be remove_reference_t<COMMON-REF(X&, Y&)>&&
3453 template<typename _Xp, typename _Yp>
3454 using __common_ref_C = remove_reference_t<__common_ref<_Xp&, _Yp&>>&&;
3455
3456 // If A and B are both rvalue reference types, ...
3457 template<typename _Xp, typename _Yp>
3458 struct __common_ref_impl<_Xp&&, _Yp&&,
3459 _Require<is_convertible<_Xp&&, __common_ref_C<_Xp, _Yp>>,
3460 is_convertible<_Yp&&, __common_ref_C<_Xp, _Yp>>>>
3461 { using type = __common_ref_C<_Xp, _Yp>; };
3462
3463 // let D be COMMON-REF(const X&, Y&)
3464 template<typename _Xp, typename _Yp>
3465 using __common_ref_D = __common_ref<const _Xp&, _Yp&>;
3466
3467 // If A is an rvalue reference and B is an lvalue reference, ...
3468 template<typename _Xp, typename _Yp>
3469 struct __common_ref_impl<_Xp&&, _Yp&,
3470 _Require<is_convertible<_Xp&&, __common_ref_D<_Xp, _Yp>>>>
3471 { using type = __common_ref_D<_Xp, _Yp>; };
3472
3473 // If A is an lvalue reference and B is an rvalue reference, ...
3474 template<typename _Xp, typename _Yp>
3475 struct __common_ref_impl<_Xp&, _Yp&&>
3476 : __common_ref_impl<_Yp&&, _Xp&>
3477 { };
3478 /// @endcond
3479
3480 template<typename _Tp, typename _Up,
3481 template<typename> class _TQual, template<typename> class _UQual>
3482 struct basic_common_reference
3483 { };
3484
3485 /// @cond undocumented
3486 template<typename _Tp>
3487 struct __xref
3488 { template<typename _Up> using __type = __copy_cv<_Tp, _Up>; };
3489
3490 template<typename _Tp>
3491 struct __xref<_Tp&>
3492 { template<typename _Up> using __type = __copy_cv<_Tp, _Up>&; };
3493
3494 template<typename _Tp>
3495 struct __xref<_Tp&&>
3496 { template<typename _Up> using __type = __copy_cv<_Tp, _Up>&&; };
3497
3498 template<typename _Tp1, typename _Tp2>
3499 using __basic_common_ref
3500 = typename basic_common_reference<remove_cvref_t<_Tp1>,
3501 remove_cvref_t<_Tp2>,
3502 __xref<_Tp1>::template __type,
3503 __xref<_Tp2>::template __type>::type;
3504 /// @endcond
3505
3506 template<typename... _Tp>
3507 struct common_reference;
3508
3509 template<typename... _Tp>
3510 using common_reference_t = typename common_reference<_Tp...>::type;
3511
3512 // If sizeof...(T) is zero, there shall be no member type.
3513 template<>
3514 struct common_reference<>
3515 { };
3516
3517 // If sizeof...(T) is one ...
3518 template<typename _Tp0>
3519 struct common_reference<_Tp0>
3520 { using type = _Tp0; };
3521
3522 /// @cond undocumented
3523 template<typename _Tp1, typename _Tp2, int _Bullet = 1, typename = void>
3524 struct __common_reference_impl
3525 : __common_reference_impl<_Tp1, _Tp2, _Bullet + 1>
3526 { };
3527
3528 // If sizeof...(T) is two ...
3529 template<typename _Tp1, typename _Tp2>
3530 struct common_reference<_Tp1, _Tp2>
3531 : __common_reference_impl<_Tp1, _Tp2>
3532 { };
3533
3534 // If T1 and T2 are reference types and COMMON-REF(T1, T2) is well-formed, ...
3535 template<typename _Tp1, typename _Tp2>
3536 struct __common_reference_impl<_Tp1&, _Tp2&, 1,
3537 void_t<__common_ref<_Tp1&, _Tp2&>>>
3538 { using type = __common_ref<_Tp1&, _Tp2&>; };
3539
3540 template<typename _Tp1, typename _Tp2>
3541 struct __common_reference_impl<_Tp1&&, _Tp2&&, 1,
3542 void_t<__common_ref<_Tp1&&, _Tp2&&>>>
3543 { using type = __common_ref<_Tp1&&, _Tp2&&>; };
3544
3545 template<typename _Tp1, typename _Tp2>
3546 struct __common_reference_impl<_Tp1&, _Tp2&&, 1,
3547 void_t<__common_ref<_Tp1&, _Tp2&&>>>
3548 { using type = __common_ref<_Tp1&, _Tp2&&>; };
3549
3550 template<typename _Tp1, typename _Tp2>
3551 struct __common_reference_impl<_Tp1&&, _Tp2&, 1,
3552 void_t<__common_ref<_Tp1&&, _Tp2&>>>
3553 { using type = __common_ref<_Tp1&&, _Tp2&>; };
3554
3555 // Otherwise, if basic_common_reference<...>::type is well-formed, ...
3556 template<typename _Tp1, typename _Tp2>
3557 struct __common_reference_impl<_Tp1, _Tp2, 2,
3558 void_t<__basic_common_ref<_Tp1, _Tp2>>>
3559 { using type = __basic_common_ref<_Tp1, _Tp2>; };
3560
3561 // Otherwise, if COND-RES(T1, T2) is well-formed, ...
3562 template<typename _Tp1, typename _Tp2>
3563 struct __common_reference_impl<_Tp1, _Tp2, 3,
3564 void_t<__cond_res<_Tp1, _Tp2>>>
3565 { using type = __cond_res<_Tp1, _Tp2>; };
3566
3567 // Otherwise, if common_type_t<T1, T2> is well-formed, ...
3568 template<typename _Tp1, typename _Tp2>
3569 struct __common_reference_impl<_Tp1, _Tp2, 4,
3570 void_t<common_type_t<_Tp1, _Tp2>>>
3571 { using type = common_type_t<_Tp1, _Tp2>; };
3572
3573 // Otherwise, there shall be no member type.
3574 template<typename _Tp1, typename _Tp2>
3575 struct __common_reference_impl<_Tp1, _Tp2, 5, void>
3576 { };
3577
3578 // Otherwise, if sizeof...(T) is greater than two, ...
3579 template<typename _Tp1, typename _Tp2, typename... _Rest>
3580 struct common_reference<_Tp1, _Tp2, _Rest...>
3581 : __common_type_fold<common_reference<_Tp1, _Tp2>,
3582 __common_type_pack<_Rest...>>
3583 { };
3584
3585 // Reuse __common_type_fold for common_reference<T1, T2, Rest...>
3586 template<typename _Tp1, typename _Tp2, typename... _Rest>
3587 struct __common_type_fold<common_reference<_Tp1, _Tp2>,
3588 __common_type_pack<_Rest...>,
3589 void_t<common_reference_t<_Tp1, _Tp2>>>
3590 : public common_reference<common_reference_t<_Tp1, _Tp2>, _Rest...>
3591 { };
3592 /// @endcond
3593
3594#endif // C++2a
3595
3596 /// @} group metaprogramming
3597
3598_GLIBCXX_END_NAMESPACE_VERSION
3599} // namespace std
3600
3601#endif // C++11
3602
3603#endif // _GLIBCXX_TYPE_TRAITS