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) && !defined(__CUDACC__)
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 // is_nothrow_convertible for C++11
1496 template<typename _From, typename _To>
1497 struct __is_nothrow_convertible
1498 : public __is_nt_convertible_helper<_From, _To>::type
1499 { };
1500
1501#if __cplusplus > 201703L
1502#define __cpp_lib_is_nothrow_convertible 201806L
1503 /// is_nothrow_convertible
1504 template<typename _From, typename _To>
1505 struct is_nothrow_convertible
1506 : public __is_nt_convertible_helper<_From, _To>::type
1507 { };
1508
1509 /// is_nothrow_convertible_v
1510 template<typename _From, typename _To>
1511 inline constexpr bool is_nothrow_convertible_v
1512 = is_nothrow_convertible<_From, _To>::value;
1513#endif // C++2a
1514
1515 // Const-volatile modifications.
1516
1517 /// remove_const
1518 template<typename _Tp>
1519 struct remove_const
1520 { typedef _Tp type; };
1521
1522 template<typename _Tp>
1523 struct remove_const<_Tp const>
1524 { typedef _Tp type; };
1525
1526 /// remove_volatile
1527 template<typename _Tp>
1528 struct remove_volatile
1529 { typedef _Tp type; };
1530
1531 template<typename _Tp>
1532 struct remove_volatile<_Tp volatile>
1533 { typedef _Tp type; };
1534
1535 /// remove_cv
1536 template<typename _Tp>
1537 struct remove_cv
1538 { using type = _Tp; };
1539
1540 template<typename _Tp>
1541 struct remove_cv<const _Tp>
1542 { using type = _Tp; };
1543
1544 template<typename _Tp>
1545 struct remove_cv<volatile _Tp>
1546 { using type = _Tp; };
1547
1548 template<typename _Tp>
1549 struct remove_cv<const volatile _Tp>
1550 { using type = _Tp; };
1551
1552 /// add_const
1553 template<typename _Tp>
1554 struct add_const
1555 { typedef _Tp const type; };
1556
1557 /// add_volatile
1558 template<typename _Tp>
1559 struct add_volatile
1560 { typedef _Tp volatile type; };
1561
1562 /// add_cv
1563 template<typename _Tp>
1564 struct add_cv
1565 {
1566 typedef typename
1567 add_const<typename add_volatile<_Tp>::type>::type type;
1568 };
1569
1570#if __cplusplus > 201103L
1571
1572#define __cpp_lib_transformation_trait_aliases 201304
1573
1574 /// Alias template for remove_const
1575 template<typename _Tp>
1576 using remove_const_t = typename remove_const<_Tp>::type;
1577
1578 /// Alias template for remove_volatile
1579 template<typename _Tp>
1580 using remove_volatile_t = typename remove_volatile<_Tp>::type;
1581
1582 /// Alias template for remove_cv
1583 template<typename _Tp>
1584 using remove_cv_t = typename remove_cv<_Tp>::type;
1585
1586 /// Alias template for add_const
1587 template<typename _Tp>
1588 using add_const_t = typename add_const<_Tp>::type;
1589
1590 /// Alias template for add_volatile
1591 template<typename _Tp>
1592 using add_volatile_t = typename add_volatile<_Tp>::type;
1593
1594 /// Alias template for add_cv
1595 template<typename _Tp>
1596 using add_cv_t = typename add_cv<_Tp>::type;
1597#endif
1598
1599 // Reference transformations.
1600
1601 /// remove_reference
1602 template<typename _Tp>
1603 struct remove_reference
1604 { typedef _Tp type; };
1605
1606 template<typename _Tp>
1607 struct remove_reference<_Tp&>
1608 { typedef _Tp type; };
1609
1610 template<typename _Tp>
1611 struct remove_reference<_Tp&&>
1612 { typedef _Tp type; };
1613
1614 template<typename _Tp, bool = __is_referenceable<_Tp>::value>
1615 struct __add_lvalue_reference_helper
1616 { typedef _Tp type; };
1617
1618 template<typename _Tp>
1619 struct __add_lvalue_reference_helper<_Tp, true>
1620 { typedef _Tp& type; };
1621
1622 /// add_lvalue_reference
1623 template<typename _Tp>
1624 struct add_lvalue_reference
1625 : public __add_lvalue_reference_helper<_Tp>
1626 { };
1627
1628 template<typename _Tp, bool = __is_referenceable<_Tp>::value>
1629 struct __add_rvalue_reference_helper
1630 { typedef _Tp type; };
1631
1632 template<typename _Tp>
1633 struct __add_rvalue_reference_helper<_Tp, true>
1634 { typedef _Tp&& type; };
1635
1636 /// add_rvalue_reference
1637 template<typename _Tp>
1638 struct add_rvalue_reference
1639 : public __add_rvalue_reference_helper<_Tp>
1640 { };
1641
1642#if __cplusplus > 201103L
1643 /// Alias template for remove_reference
1644 template<typename _Tp>
1645 using remove_reference_t = typename remove_reference<_Tp>::type;
1646
1647 /// Alias template for add_lvalue_reference
1648 template<typename _Tp>
1649 using add_lvalue_reference_t = typename add_lvalue_reference<_Tp>::type;
1650
1651 /// Alias template for add_rvalue_reference
1652 template<typename _Tp>
1653 using add_rvalue_reference_t = typename add_rvalue_reference<_Tp>::type;
1654#endif
1655
1656 // Sign modifications.
1657
1658 /// @cond undocumented
1659
1660 // Utility for constructing identically cv-qualified types.
1661 template<typename _Unqualified, bool _IsConst, bool _IsVol>
1662 struct __cv_selector;
1663
1664 template<typename _Unqualified>
1665 struct __cv_selector<_Unqualified, false, false>
1666 { typedef _Unqualified __type; };
1667
1668 template<typename _Unqualified>
1669 struct __cv_selector<_Unqualified, false, true>
1670 { typedef volatile _Unqualified __type; };
1671
1672 template<typename _Unqualified>
1673 struct __cv_selector<_Unqualified, true, false>
1674 { typedef const _Unqualified __type; };
1675
1676 template<typename _Unqualified>
1677 struct __cv_selector<_Unqualified, true, true>
1678 { typedef const volatile _Unqualified __type; };
1679
1680 template<typename _Qualified, typename _Unqualified,
1681 bool _IsConst = is_const<_Qualified>::value,
1682 bool _IsVol = is_volatile<_Qualified>::value>
1683 class __match_cv_qualifiers
1684 {
1685 typedef __cv_selector<_Unqualified, _IsConst, _IsVol> __match;
1686
1687 public:
1688 typedef typename __match::__type __type;
1689 };
1690
1691 // Utility for finding the unsigned versions of signed integral types.
1692 template<typename _Tp>
1693 struct __make_unsigned
1694 { typedef _Tp __type; };
1695
1696 template<>
1697 struct __make_unsigned<char>
1698 { typedef unsigned char __type; };
1699
1700 template<>
1701 struct __make_unsigned<signed char>
1702 { typedef unsigned char __type; };
1703
1704 template<>
1705 struct __make_unsigned<short>
1706 { typedef unsigned short __type; };
1707
1708 template<>
1709 struct __make_unsigned<int>
1710 { typedef unsigned int __type; };
1711
1712 template<>
1713 struct __make_unsigned<long>
1714 { typedef unsigned long __type; };
1715
1716 template<>
1717 struct __make_unsigned<long long>
1718 { typedef unsigned long long __type; };
1719
1720#if defined(__GLIBCXX_TYPE_INT_N_0)
1721 template<>
1722 struct __make_unsigned<__GLIBCXX_TYPE_INT_N_0>
1723 { typedef unsigned __GLIBCXX_TYPE_INT_N_0 __type; };
1724#endif
1725#if defined(__GLIBCXX_TYPE_INT_N_1)
1726 template<>
1727 struct __make_unsigned<__GLIBCXX_TYPE_INT_N_1>
1728 { typedef unsigned __GLIBCXX_TYPE_INT_N_1 __type; };
1729#endif
1730#if defined(__GLIBCXX_TYPE_INT_N_2)
1731 template<>
1732 struct __make_unsigned<__GLIBCXX_TYPE_INT_N_2>
1733 { typedef unsigned __GLIBCXX_TYPE_INT_N_2 __type; };
1734#endif
1735#if defined(__GLIBCXX_TYPE_INT_N_3)
1736 template<>
1737 struct __make_unsigned<__GLIBCXX_TYPE_INT_N_3>
1738 { typedef unsigned __GLIBCXX_TYPE_INT_N_3 __type; };
1739#endif
1740
1741 // Select between integral and enum: not possible to be both.
1742 template<typename _Tp,
1743 bool _IsInt = is_integral<_Tp>::value,
1744 bool _IsEnum = is_enum<_Tp>::value>
1745 class __make_unsigned_selector;
1746
1747 template<typename _Tp>
1748 class __make_unsigned_selector<_Tp, true, false>
1749 {
1750 using __unsigned_type
1751 = typename __make_unsigned<__remove_cv_t<_Tp>>::__type;
1752
1753 public:
1754 using __type
1755 = typename __match_cv_qualifiers<_Tp, __unsigned_type>::__type;
1756 };
1757
1758 class __make_unsigned_selector_base
1759 {
1760 protected:
1761 template<typename...> struct _List { };
1762
1763 template<typename _Tp, typename... _Up>
1764 struct _List<_Tp, _Up...> : _List<_Up...>
1765 { static constexpr size_t __size = sizeof(_Tp); };
1766
1767 template<size_t _Sz, typename _Tp, bool = (_Sz <= _Tp::__size)>
1768 struct __select;
1769
1770 template<size_t _Sz, typename _Uint, typename... _UInts>
1771 struct __select<_Sz, _List<_Uint, _UInts...>, true>
1772 { using __type = _Uint; };
1773
1774 template<size_t _Sz, typename _Uint, typename... _UInts>
1775 struct __select<_Sz, _List<_Uint, _UInts...>, false>
1776 : __select<_Sz, _List<_UInts...>>
1777 { };
1778 };
1779
1780 // Choose unsigned integer type with the smallest rank and same size as _Tp
1781 template<typename _Tp>
1782 class __make_unsigned_selector<_Tp, false, true>
1783 : __make_unsigned_selector_base
1784 {
1785 // With -fshort-enums, an enum may be as small as a char.
1786 using _UInts = _List<unsigned char, unsigned short, unsigned int,
1787 unsigned long, unsigned long long>;
1788
1789 using __unsigned_type = typename __select<sizeof(_Tp), _UInts>::__type;
1790
1791 public:
1792 using __type
1793 = typename __match_cv_qualifiers<_Tp, __unsigned_type>::__type;
1794 };
1795
1796 // wchar_t, char8_t, char16_t and char32_t are integral types but are
1797 // neither signed integer types nor unsigned integer types, so must be
1798 // transformed to the unsigned integer type with the smallest rank.
1799 // Use the partial specialization for enumeration types to do that.
1800#ifdef __WCHAR_TYPE__
1801 template<>
1802 struct __make_unsigned<wchar_t>
1803 {
1804 using __type
1805 = typename __make_unsigned_selector<wchar_t, false, true>::__type;
1806 };
1807#endif
1808
1809#ifdef _GLIBCXX_USE_CHAR8_T
1810 template<>
1811 struct __make_unsigned<char8_t>
1812 {
1813 using __type
1814 = typename __make_unsigned_selector<char8_t, false, true>::__type;
1815 };
1816#endif
1817
1818 template<>
1819 struct __make_unsigned<char16_t>
1820 {
1821 using __type
1822 = typename __make_unsigned_selector<char16_t, false, true>::__type;
1823 };
1824
1825 template<>
1826 struct __make_unsigned<char32_t>
1827 {
1828 using __type
1829 = typename __make_unsigned_selector<char32_t, false, true>::__type;
1830 };
1831 /// @endcond
1832
1833 // Given an integral/enum type, return the corresponding unsigned
1834 // integer type.
1835 // Primary template.
1836 /// make_unsigned
1837 template<typename _Tp>
1838 struct make_unsigned
1839 { typedef typename __make_unsigned_selector<_Tp>::__type type; };
1840
1841 // Integral, but don't define.
1842 template<>
1843 struct make_unsigned<bool>;
1844
1845 /// @cond undocumented
1846
1847 // Utility for finding the signed versions of unsigned integral types.
1848 template<typename _Tp>
1849 struct __make_signed
1850 { typedef _Tp __type; };
1851
1852 template<>
1853 struct __make_signed<char>
1854 { typedef signed char __type; };
1855
1856 template<>
1857 struct __make_signed<unsigned char>
1858 { typedef signed char __type; };
1859
1860 template<>
1861 struct __make_signed<unsigned short>
1862 { typedef signed short __type; };
1863
1864 template<>
1865 struct __make_signed<unsigned int>
1866 { typedef signed int __type; };
1867
1868 template<>
1869 struct __make_signed<unsigned long>
1870 { typedef signed long __type; };
1871
1872 template<>
1873 struct __make_signed<unsigned long long>
1874 { typedef signed long long __type; };
1875
1876#if defined(__GLIBCXX_TYPE_INT_N_0)
1877 template<>
1878 struct __make_signed<unsigned __GLIBCXX_TYPE_INT_N_0>
1879 { typedef __GLIBCXX_TYPE_INT_N_0 __type; };
1880#endif
1881#if defined(__GLIBCXX_TYPE_INT_N_1)
1882 template<>
1883 struct __make_signed<unsigned __GLIBCXX_TYPE_INT_N_1>
1884 { typedef __GLIBCXX_TYPE_INT_N_1 __type; };
1885#endif
1886#if defined(__GLIBCXX_TYPE_INT_N_2)
1887 template<>
1888 struct __make_signed<unsigned __GLIBCXX_TYPE_INT_N_2>
1889 { typedef __GLIBCXX_TYPE_INT_N_2 __type; };
1890#endif
1891#if defined(__GLIBCXX_TYPE_INT_N_3)
1892 template<>
1893 struct __make_signed<unsigned __GLIBCXX_TYPE_INT_N_3>
1894 { typedef __GLIBCXX_TYPE_INT_N_3 __type; };
1895#endif
1896
1897 // Select between integral and enum: not possible to be both.
1898 template<typename _Tp,
1899 bool _IsInt = is_integral<_Tp>::value,
1900 bool _IsEnum = is_enum<_Tp>::value>
1901 class __make_signed_selector;
1902
1903 template<typename _Tp>
1904 class __make_signed_selector<_Tp, true, false>
1905 {
1906 using __signed_type
1907 = typename __make_signed<__remove_cv_t<_Tp>>::__type;
1908
1909 public:
1910 using __type
1911 = typename __match_cv_qualifiers<_Tp, __signed_type>::__type;
1912 };
1913
1914 // Choose signed integer type with the smallest rank and same size as _Tp
1915 template<typename _Tp>
1916 class __make_signed_selector<_Tp, false, true>
1917 {
1918 typedef typename __make_unsigned_selector<_Tp>::__type __unsigned_type;
1919
1920 public:
1921 typedef typename __make_signed_selector<__unsigned_type>::__type __type;
1922 };
1923
1924 // wchar_t, char16_t and char32_t are integral types but are neither
1925 // signed integer types nor unsigned integer types, so must be
1926 // transformed to the signed integer type with the smallest rank.
1927 // Use the partial specialization for enumeration types to do that.
1928#if defined(__WCHAR_TYPE__)
1929 template<>
1930 struct __make_signed<wchar_t>
1931 {
1932 using __type
1933 = typename __make_signed_selector<wchar_t, false, true>::__type;
1934 };
1935#endif
1936
1937#if defined(_GLIBCXX_USE_CHAR8_T)
1938 template<>
1939 struct __make_signed<char8_t>
1940 {
1941 using __type
1942 = typename __make_signed_selector<char8_t, false, true>::__type;
1943 };
1944#endif
1945
1946 template<>
1947 struct __make_signed<char16_t>
1948 {
1949 using __type
1950 = typename __make_signed_selector<char16_t, false, true>::__type;
1951 };
1952
1953 template<>
1954 struct __make_signed<char32_t>
1955 {
1956 using __type
1957 = typename __make_signed_selector<char32_t, false, true>::__type;
1958 };
1959 /// @endcond
1960
1961 // Given an integral/enum type, return the corresponding signed
1962 // integer type.
1963 // Primary template.
1964 /// make_signed
1965 template<typename _Tp>
1966 struct make_signed
1967 { typedef typename __make_signed_selector<_Tp>::__type type; };
1968
1969 // Integral, but don't define.
1970 template<>
1971 struct make_signed<bool>;
1972
1973#if __cplusplus > 201103L
1974 /// Alias template for make_signed
1975 template<typename _Tp>
1976 using make_signed_t = typename make_signed<_Tp>::type;
1977
1978 /// Alias template for make_unsigned
1979 template<typename _Tp>
1980 using make_unsigned_t = typename make_unsigned<_Tp>::type;
1981#endif
1982
1983 // Array modifications.
1984
1985 /// remove_extent
1986 template<typename _Tp>
1987 struct remove_extent
1988 { typedef _Tp type; };
1989
1990 template<typename _Tp, std::size_t _Size>
1991 struct remove_extent<_Tp[_Size]>
1992 { typedef _Tp type; };
1993
1994 template<typename _Tp>
1995 struct remove_extent<_Tp[]>
1996 { typedef _Tp type; };
1997
1998 /// remove_all_extents
1999 template<typename _Tp>
2000 struct remove_all_extents
2001 { typedef _Tp type; };
2002
2003 template<typename _Tp, std::size_t _Size>
2004 struct remove_all_extents<_Tp[_Size]>
2005 { typedef typename remove_all_extents<_Tp>::type type; };
2006
2007 template<typename _Tp>
2008 struct remove_all_extents<_Tp[]>
2009 { typedef typename remove_all_extents<_Tp>::type type; };
2010
2011#if __cplusplus > 201103L
2012 /// Alias template for remove_extent
2013 template<typename _Tp>
2014 using remove_extent_t = typename remove_extent<_Tp>::type;
2015
2016 /// Alias template for remove_all_extents
2017 template<typename _Tp>
2018 using remove_all_extents_t = typename remove_all_extents<_Tp>::type;
2019#endif
2020
2021 // Pointer modifications.
2022
2023 template<typename _Tp, typename>
2024 struct __remove_pointer_helper
2025 { typedef _Tp type; };
2026
2027 template<typename _Tp, typename _Up>
2028 struct __remove_pointer_helper<_Tp, _Up*>
2029 { typedef _Up type; };
2030
2031 /// remove_pointer
2032 template<typename _Tp>
2033 struct remove_pointer
2034 : public __remove_pointer_helper<_Tp, __remove_cv_t<_Tp>>
2035 { };
2036
2037 template<typename _Tp, bool = __or_<__is_referenceable<_Tp>,
2038 is_void<_Tp>>::value>
2039 struct __add_pointer_helper
2040 { typedef _Tp type; };
2041
2042 template<typename _Tp>
2043 struct __add_pointer_helper<_Tp, true>
2044 { typedef typename remove_reference<_Tp>::type* type; };
2045
2046 /// add_pointer
2047 template<typename _Tp>
2048 struct add_pointer
2049 : public __add_pointer_helper<_Tp>
2050 { };
2051
2052#if __cplusplus > 201103L
2053 /// Alias template for remove_pointer
2054 template<typename _Tp>
2055 using remove_pointer_t = typename remove_pointer<_Tp>::type;
2056
2057 /// Alias template for add_pointer
2058 template<typename _Tp>
2059 using add_pointer_t = typename add_pointer<_Tp>::type;
2060#endif
2061
2062 template<std::size_t _Len>
2063 struct __aligned_storage_msa
2064 {
2065 union __type
2066 {
2067 unsigned char __data[_Len];
2068 struct __attribute__((__aligned__)) { } __align;
2069 };
2070 };
2071
2072 /**
2073 * @brief Alignment type.
2074 *
2075 * The value of _Align is a default-alignment which shall be the
2076 * most stringent alignment requirement for any C++ object type
2077 * whose size is no greater than _Len (3.9). The member typedef
2078 * type shall be a POD type suitable for use as uninitialized
2079 * storage for any object whose size is at most _Len and whose
2080 * alignment is a divisor of _Align.
2081 */
2082 template<std::size_t _Len, std::size_t _Align =
2083 __alignof__(typename __aligned_storage_msa<_Len>::__type)>
2084 struct aligned_storage
2085 {
2086 union type
2087 {
2088 unsigned char __data[_Len];
2089 struct __attribute__((__aligned__((_Align)))) { } __align;
2090 };
2091 };
2092
2093 template <typename... _Types>
2094 struct __strictest_alignment
2095 {
2096 static const size_t _S_alignment = 0;
2097 static const size_t _S_size = 0;
2098 };
2099
2100 template <typename _Tp, typename... _Types>
2101 struct __strictest_alignment<_Tp, _Types...>
2102 {
2103 static const size_t _S_alignment =
2104 alignof(_Tp) > __strictest_alignment<_Types...>::_S_alignment
2105 ? alignof(_Tp) : __strictest_alignment<_Types...>::_S_alignment;
2106 static const size_t _S_size =
2107 sizeof(_Tp) > __strictest_alignment<_Types...>::_S_size
2108 ? sizeof(_Tp) : __strictest_alignment<_Types...>::_S_size;
2109 };
2110
2111 /**
2112 * @brief Provide aligned storage for types.
2113 *
2114 * [meta.trans.other]
2115 *
2116 * Provides aligned storage for any of the provided types of at
2117 * least size _Len.
2118 *
2119 * @see aligned_storage
2120 */
2121 template <size_t _Len, typename... _Types>
2122 struct aligned_union
2123 {
2124 private:
2125 static_assert(sizeof...(_Types) != 0, "At least one type is required");
2126
2127 using __strictest = __strictest_alignment<_Types...>;
2128 static const size_t _S_len = _Len > __strictest::_S_size
2129 ? _Len : __strictest::_S_size;
2130 public:
2131 /// The value of the strictest alignment of _Types.
2132 static const size_t alignment_value = __strictest::_S_alignment;
2133 /// The storage.
2134 typedef typename aligned_storage<_S_len, alignment_value>::type type;
2135 };
2136
2137 template <size_t _Len, typename... _Types>
2138 const size_t aligned_union<_Len, _Types...>::alignment_value;
2139
2140 /// @cond undocumented
2141
2142 // Decay trait for arrays and functions, used for perfect forwarding
2143 // in make_pair, make_tuple, etc.
2144 template<typename _Up,
2145 bool _IsArray = is_array<_Up>::value,
2146 bool _IsFunction = is_function<_Up>::value>
2147 struct __decay_selector;
2148
2149 // NB: DR 705.
2150 template<typename _Up>
2151 struct __decay_selector<_Up, false, false>
2152 { typedef __remove_cv_t<_Up> __type; };
2153
2154 template<typename _Up>
2155 struct __decay_selector<_Up, true, false>
2156 { typedef typename remove_extent<_Up>::type* __type; };
2157
2158 template<typename _Up>
2159 struct __decay_selector<_Up, false, true>
2160 { typedef typename add_pointer<_Up>::type __type; };
2161 /// @endcond
2162
2163 /// decay
2164 template<typename _Tp>
2165 class decay
2166 {
2167 typedef typename remove_reference<_Tp>::type __remove_type;
2168
2169 public:
2170 typedef typename __decay_selector<__remove_type>::__type type;
2171 };
2172
2173 /// @cond undocumented
2174
2175 // Helper which adds a reference to a type when given a reference_wrapper
2176 template<typename _Tp>
2177 struct __strip_reference_wrapper
2178 {
2179 typedef _Tp __type;
2180 };
2181
2182 template<typename _Tp>
2183 struct __strip_reference_wrapper<reference_wrapper<_Tp> >
2184 {
2185 typedef _Tp& __type;
2186 };
2187
2188 // __decay_t (std::decay_t for C++11).
2189 template<typename _Tp>
2190 using __decay_t = typename decay<_Tp>::type;
2191
2192 template<typename _Tp>
2193 using __decay_and_strip = __strip_reference_wrapper<__decay_t<_Tp>>;
2194 /// @endcond
2195
2196 // Primary template.
2197 /// Define a member typedef `type` only if a boolean constant is true.
2198 template<bool, typename _Tp = void>
2199 struct enable_if
2200 { };
2201
2202 // Partial specialization for true.
2203 template<typename _Tp>
2204 struct enable_if<true, _Tp>
2205 { typedef _Tp type; };
2206
2207 /// @cond undocumented
2208
2209 // __enable_if_t (std::enable_if_t for C++11)
2210 template<bool _Cond, typename _Tp = void>
2211 using __enable_if_t = typename enable_if<_Cond, _Tp>::type;
2212
2213 // Helper for SFINAE constraints
2214 template<typename... _Cond>
2215 using _Require = __enable_if_t<__and_<_Cond...>::value>;
2216
2217 // __remove_cvref_t (std::remove_cvref_t for C++11).
2218 template<typename _Tp>
2219 using __remove_cvref_t
2220 = typename remove_cv<typename remove_reference<_Tp>::type>::type;
2221 /// @endcond
2222
2223 // Primary template.
2224 /// Define a member typedef @c type to one of two argument types.
2225 template<bool _Cond, typename _Iftrue, typename _Iffalse>
2226 struct conditional
2227 { typedef _Iftrue type; };
2228
2229 // Partial specialization for false.
2230 template<typename _Iftrue, typename _Iffalse>
2231 struct conditional<false, _Iftrue, _Iffalse>
2232 { typedef _Iffalse type; };
2233
2234 /// common_type
2235 template<typename... _Tp>
2236 struct common_type;
2237
2238 // Sfinae-friendly common_type implementation:
2239
2240 /// @cond undocumented
2241 struct __do_common_type_impl
2242 {
2243 template<typename _Tp, typename _Up>
2244 using __cond_t
2245 = decltype(true ? std::declval<_Tp>() : std::declval<_Up>());
2246
2247 // if decay_t<decltype(false ? declval<D1>() : declval<D2>())>
2248 // denotes a valid type, let C denote that type.
2249 template<typename _Tp, typename _Up>
2250 static __success_type<__decay_t<__cond_t<_Tp, _Up>>>
2251 _S_test(int);
2252
2253#if __cplusplus > 201703L
2254 // Otherwise, if COND-RES(CREF(D1), CREF(D2)) denotes a type,
2255 // let C denote the type decay_t<COND-RES(CREF(D1), CREF(D2))>.
2256 template<typename _Tp, typename _Up>
2257 static __success_type<__remove_cvref_t<__cond_t<const _Tp&, const _Up&>>>
2258 _S_test_2(int);
2259#endif
2260
2261 template<typename, typename>
2262 static __failure_type
2263 _S_test_2(...);
2264
2265 template<typename _Tp, typename _Up>
2266 static decltype(_S_test_2<_Tp, _Up>(0))
2267 _S_test(...);
2268 };
2269
2270 // If sizeof...(T) is zero, there shall be no member type.
2271 template<>
2272 struct common_type<>
2273 { };
2274
2275 // If sizeof...(T) is one, the same type, if any, as common_type_t<T0, T0>.
2276 template<typename _Tp0>
2277 struct common_type<_Tp0>
2278 : public common_type<_Tp0, _Tp0>
2279 { };
2280
2281 // If sizeof...(T) is two, ...
2282 template<typename _Tp1, typename _Tp2,
2283 typename _Dp1 = __decay_t<_Tp1>, typename _Dp2 = __decay_t<_Tp2>>
2284 struct __common_type_impl
2285 {
2286 // If is_same_v<T1, D1> is false or is_same_v<T2, D2> is false,
2287 // let C denote the same type, if any, as common_type_t<D1, D2>.
2288 using type = common_type<_Dp1, _Dp2>;
2289 };
2290
2291 template<typename _Tp1, typename _Tp2>
2292 struct __common_type_impl<_Tp1, _Tp2, _Tp1, _Tp2>
2293 : private __do_common_type_impl
2294 {
2295 // Otherwise, if decay_t<decltype(false ? declval<D1>() : declval<D2>())>
2296 // denotes a valid type, let C denote that type.
2297 using type = decltype(_S_test<_Tp1, _Tp2>(0));
2298 };
2299
2300 // If sizeof...(T) is two, ...
2301 template<typename _Tp1, typename _Tp2>
2302 struct common_type<_Tp1, _Tp2>
2303 : public __common_type_impl<_Tp1, _Tp2>::type
2304 { };
2305
2306 template<typename...>
2307 struct __common_type_pack
2308 { };
2309
2310 template<typename, typename, typename = void>
2311 struct __common_type_fold;
2312
2313 // If sizeof...(T) is greater than two, ...
2314 template<typename _Tp1, typename _Tp2, typename... _Rp>
2315 struct common_type<_Tp1, _Tp2, _Rp...>
2316 : public __common_type_fold<common_type<_Tp1, _Tp2>,
2317 __common_type_pack<_Rp...>>
2318 { };
2319
2320 // Let C denote the same type, if any, as common_type_t<T1, T2>.
2321 // If there is such a type C, type shall denote the same type, if any,
2322 // as common_type_t<C, R...>.
2323 template<typename _CTp, typename... _Rp>
2324 struct __common_type_fold<_CTp, __common_type_pack<_Rp...>,
2325 __void_t<typename _CTp::type>>
2326 : public common_type<typename _CTp::type, _Rp...>
2327 { };
2328
2329 // Otherwise, there shall be no member type.
2330 template<typename _CTp, typename _Rp>
2331 struct __common_type_fold<_CTp, _Rp, void>
2332 { };
2333
2334 template<typename _Tp, bool = is_enum<_Tp>::value>
2335 struct __underlying_type_impl
2336 {
2337 using type = __underlying_type(_Tp);
2338 };
2339
2340 template<typename _Tp>
2341 struct __underlying_type_impl<_Tp, false>
2342 { };
2343 /// @endcond
2344
2345 /// The underlying type of an enum.
2346 template<typename _Tp>
2347 struct underlying_type
2348 : public __underlying_type_impl<_Tp>
2349 { };
2350
2351 /// @cond undocumented
2352 template<typename _Tp>
2353 struct __declval_protector
2354 {
2355 static const bool __stop = false;
2356 };
2357 /// @endcond
2358
2359 /** Utility to simplify expressions used in unevaluated operands
2360 * @since C++11
2361 * @ingroup utilities
2362 */
2363 template<typename _Tp>
2364 auto declval() noexcept -> decltype(__declval<_Tp>(0))
2365 {
2366 static_assert(__declval_protector<_Tp>::__stop,
2367 "declval() must not be used!");
2368 return __declval<_Tp>(0);
2369 }
2370
2371 /// result_of
2372 template<typename _Signature>
2373 struct result_of;
2374
2375 // Sfinae-friendly result_of implementation:
2376
2377#define __cpp_lib_result_of_sfinae 201210
2378
2379 /// @cond undocumented
2380 struct __invoke_memfun_ref { };
2381 struct __invoke_memfun_deref { };
2382 struct __invoke_memobj_ref { };
2383 struct __invoke_memobj_deref { };
2384 struct __invoke_other { };
2385
2386 // Associate a tag type with a specialization of __success_type.
2387 template<typename _Tp, typename _Tag>
2388 struct __result_of_success : __success_type<_Tp>
2389 { using __invoke_type = _Tag; };
2390
2391 // [func.require] paragraph 1 bullet 1:
2392 struct __result_of_memfun_ref_impl
2393 {
2394 template<typename _Fp, typename _Tp1, typename... _Args>
2395 static __result_of_success<decltype(
2396 (std::declval<_Tp1>().*std::declval<_Fp>())(std::declval<_Args>()...)
2397 ), __invoke_memfun_ref> _S_test(int);
2398
2399 template<typename...>
2400 static __failure_type _S_test(...);
2401 };
2402
2403 template<typename _MemPtr, typename _Arg, typename... _Args>
2404 struct __result_of_memfun_ref
2405 : private __result_of_memfun_ref_impl
2406 {
2407 typedef decltype(_S_test<_MemPtr, _Arg, _Args...>(0)) type;
2408 };
2409
2410 // [func.require] paragraph 1 bullet 2:
2411 struct __result_of_memfun_deref_impl
2412 {
2413 template<typename _Fp, typename _Tp1, typename... _Args>
2414 static __result_of_success<decltype(
2415 ((*std::declval<_Tp1>()).*std::declval<_Fp>())(std::declval<_Args>()...)
2416 ), __invoke_memfun_deref> _S_test(int);
2417
2418 template<typename...>
2419 static __failure_type _S_test(...);
2420 };
2421
2422 template<typename _MemPtr, typename _Arg, typename... _Args>
2423 struct __result_of_memfun_deref
2424 : private __result_of_memfun_deref_impl
2425 {
2426 typedef decltype(_S_test<_MemPtr, _Arg, _Args...>(0)) type;
2427 };
2428
2429 // [func.require] paragraph 1 bullet 3:
2430 struct __result_of_memobj_ref_impl
2431 {
2432 template<typename _Fp, typename _Tp1>
2433 static __result_of_success<decltype(
2434 std::declval<_Tp1>().*std::declval<_Fp>()
2435 ), __invoke_memobj_ref> _S_test(int);
2436
2437 template<typename, typename>
2438 static __failure_type _S_test(...);
2439 };
2440
2441 template<typename _MemPtr, typename _Arg>
2442 struct __result_of_memobj_ref
2443 : private __result_of_memobj_ref_impl
2444 {
2445 typedef decltype(_S_test<_MemPtr, _Arg>(0)) type;
2446 };
2447
2448 // [func.require] paragraph 1 bullet 4:
2449 struct __result_of_memobj_deref_impl
2450 {
2451 template<typename _Fp, typename _Tp1>
2452 static __result_of_success<decltype(
2453 (*std::declval<_Tp1>()).*std::declval<_Fp>()
2454 ), __invoke_memobj_deref> _S_test(int);
2455
2456 template<typename, typename>
2457 static __failure_type _S_test(...);
2458 };
2459
2460 template<typename _MemPtr, typename _Arg>
2461 struct __result_of_memobj_deref
2462 : private __result_of_memobj_deref_impl
2463 {
2464 typedef decltype(_S_test<_MemPtr, _Arg>(0)) type;
2465 };
2466
2467 template<typename _MemPtr, typename _Arg>
2468 struct __result_of_memobj;
2469
2470 template<typename _Res, typename _Class, typename _Arg>
2471 struct __result_of_memobj<_Res _Class::*, _Arg>
2472 {
2473 typedef __remove_cvref_t<_Arg> _Argval;
2474 typedef _Res _Class::* _MemPtr;
2475 typedef typename conditional<__or_<is_same<_Argval, _Class>,
2476 is_base_of<_Class, _Argval>>::value,
2477 __result_of_memobj_ref<_MemPtr, _Arg>,
2478 __result_of_memobj_deref<_MemPtr, _Arg>
2479 >::type::type type;
2480 };
2481
2482 template<typename _MemPtr, typename _Arg, typename... _Args>
2483 struct __result_of_memfun;
2484
2485 template<typename _Res, typename _Class, typename _Arg, typename... _Args>
2486 struct __result_of_memfun<_Res _Class::*, _Arg, _Args...>
2487 {
2488 typedef typename remove_reference<_Arg>::type _Argval;
2489 typedef _Res _Class::* _MemPtr;
2490 typedef typename conditional<is_base_of<_Class, _Argval>::value,
2491 __result_of_memfun_ref<_MemPtr, _Arg, _Args...>,
2492 __result_of_memfun_deref<_MemPtr, _Arg, _Args...>
2493 >::type::type type;
2494 };
2495
2496 // _GLIBCXX_RESOLVE_LIB_DEFECTS
2497 // 2219. INVOKE-ing a pointer to member with a reference_wrapper
2498 // as the object expression
2499
2500 // Used by result_of, invoke etc. to unwrap a reference_wrapper.
2501 template<typename _Tp, typename _Up = __remove_cvref_t<_Tp>>
2502 struct __inv_unwrap
2503 {
2504 using type = _Tp;
2505 };
2506
2507 template<typename _Tp, typename _Up>
2508 struct __inv_unwrap<_Tp, reference_wrapper<_Up>>
2509 {
2510 using type = _Up&;
2511 };
2512
2513 template<bool, bool, typename _Functor, typename... _ArgTypes>
2514 struct __result_of_impl
2515 {
2516 typedef __failure_type type;
2517 };
2518
2519 template<typename _MemPtr, typename _Arg>
2520 struct __result_of_impl<true, false, _MemPtr, _Arg>
2521 : public __result_of_memobj<__decay_t<_MemPtr>,
2522 typename __inv_unwrap<_Arg>::type>
2523 { };
2524
2525 template<typename _MemPtr, typename _Arg, typename... _Args>
2526 struct __result_of_impl<false, true, _MemPtr, _Arg, _Args...>
2527 : public __result_of_memfun<__decay_t<_MemPtr>,
2528 typename __inv_unwrap<_Arg>::type, _Args...>
2529 { };
2530
2531 // [func.require] paragraph 1 bullet 5:
2532 struct __result_of_other_impl
2533 {
2534 template<typename _Fn, typename... _Args>
2535 static __result_of_success<decltype(
2536 std::declval<_Fn>()(std::declval<_Args>()...)
2537 ), __invoke_other> _S_test(int);
2538
2539 template<typename...>
2540 static __failure_type _S_test(...);
2541 };
2542
2543 template<typename _Functor, typename... _ArgTypes>
2544 struct __result_of_impl<false, false, _Functor, _ArgTypes...>
2545 : private __result_of_other_impl
2546 {
2547 typedef decltype(_S_test<_Functor, _ArgTypes...>(0)) type;
2548 };
2549
2550 // __invoke_result (std::invoke_result for C++11)
2551 template<typename _Functor, typename... _ArgTypes>
2552 struct __invoke_result
2553 : public __result_of_impl<
2554 is_member_object_pointer<
2555 typename remove_reference<_Functor>::type
2556 >::value,
2557 is_member_function_pointer<
2558 typename remove_reference<_Functor>::type
2559 >::value,
2560 _Functor, _ArgTypes...
2561 >::type
2562 { };
2563 /// @endcond
2564
2565 template<typename _Functor, typename... _ArgTypes>
2566 struct result_of<_Functor(_ArgTypes...)>
2567 : public __invoke_result<_Functor, _ArgTypes...>
2568 { };
2569
2570#if __cplusplus >= 201402L
2571 /// Alias template for aligned_storage
2572 template<size_t _Len, size_t _Align =
2573 __alignof__(typename __aligned_storage_msa<_Len>::__type)>
2574 using aligned_storage_t = typename aligned_storage<_Len, _Align>::type;
2575
2576 template <size_t _Len, typename... _Types>
2577 using aligned_union_t = typename aligned_union<_Len, _Types...>::type;
2578
2579 /// Alias template for decay
2580 template<typename _Tp>
2581 using decay_t = typename decay<_Tp>::type;
2582
2583 /// Alias template for enable_if
2584 template<bool _Cond, typename _Tp = void>
2585 using enable_if_t = typename enable_if<_Cond, _Tp>::type;
2586
2587 /// Alias template for conditional
2588 template<bool _Cond, typename _Iftrue, typename _Iffalse>
2589 using conditional_t = typename conditional<_Cond, _Iftrue, _Iffalse>::type;
2590
2591 /// Alias template for common_type
2592 template<typename... _Tp>
2593 using common_type_t = typename common_type<_Tp...>::type;
2594
2595 /// Alias template for underlying_type
2596 template<typename _Tp>
2597 using underlying_type_t = typename underlying_type<_Tp>::type;
2598
2599 /// Alias template for result_of
2600 template<typename _Tp>
2601 using result_of_t = typename result_of<_Tp>::type;
2602#endif // C++14
2603
2604#if __cplusplus >= 201703L || !defined(__STRICT_ANSI__) // c++17 or gnu++11
2605#define __cpp_lib_void_t 201411
2606 /// A metafunction that always yields void, used for detecting valid types.
2607 template<typename...> using void_t = void;
2608#endif
2609
2610 /// @cond undocumented
2611
2612 /// Implementation of the detection idiom (negative case).
2613 template<typename _Default, typename _AlwaysVoid,
2614 template<typename...> class _Op, typename... _Args>
2615 struct __detector
2616 {
2617 using value_t = false_type;
2618 using type = _Default;
2619 };
2620
2621 /// Implementation of the detection idiom (positive case).
2622 template<typename _Default, template<typename...> class _Op,
2623 typename... _Args>
2624 struct __detector<_Default, __void_t<_Op<_Args...>>, _Op, _Args...>
2625 {
2626 using value_t = true_type;
2627 using type = _Op<_Args...>;
2628 };
2629
2630 // Detect whether _Op<_Args...> is a valid type, use _Default if not.
2631 template<typename _Default, template<typename...> class _Op,
2632 typename... _Args>
2633 using __detected_or = __detector<_Default, void, _Op, _Args...>;
2634
2635 // _Op<_Args...> if that is a valid type, otherwise _Default.
2636 template<typename _Default, template<typename...> class _Op,
2637 typename... _Args>
2638 using __detected_or_t
2639 = typename __detected_or<_Default, _Op, _Args...>::type;
2640
2641 /**
2642 * Use SFINAE to determine if the type _Tp has a publicly-accessible
2643 * member type _NTYPE.
2644 */
2645#define _GLIBCXX_HAS_NESTED_TYPE(_NTYPE) \
2646 template<typename _Tp, typename = __void_t<>> \
2647 struct __has_##_NTYPE \
2648 : false_type \
2649 { }; \
2650 template<typename _Tp> \
2651 struct __has_##_NTYPE<_Tp, __void_t<typename _Tp::_NTYPE>> \
2652 : true_type \
2653 { };
2654
2655 template <typename _Tp>
2656 struct __is_swappable;
2657
2658 template <typename _Tp>
2659 struct __is_nothrow_swappable;
2660
2661 template<typename>
2662 struct __is_tuple_like_impl : false_type
2663 { };
2664
2665 template<typename... _Tps>
2666 struct __is_tuple_like_impl<tuple<_Tps...>> : true_type
2667 { };
2668
2669 // Internal type trait that allows us to sfinae-protect tuple_cat.
2670 template<typename _Tp>
2671 struct __is_tuple_like
2672 : public __is_tuple_like_impl<__remove_cvref_t<_Tp>>::type
2673 { };
2674 /// @endcond
2675
2676 template<typename _Tp>
2677 _GLIBCXX20_CONSTEXPR
2678 inline
2679 _Require<__not_<__is_tuple_like<_Tp>>,
2680 is_move_constructible<_Tp>,
2681 is_move_assignable<_Tp>>
2682 swap(_Tp&, _Tp&)
2683 noexcept(__and_<is_nothrow_move_constructible<_Tp>,
2684 is_nothrow_move_assignable<_Tp>>::value);
2685
2686 template<typename _Tp, size_t _Nm>
2687 _GLIBCXX20_CONSTEXPR
2688 inline
2689 __enable_if_t<__is_swappable<_Tp>::value>
2690 swap(_Tp (&__a)[_Nm], _Tp (&__b)[_Nm])
2691 noexcept(__is_nothrow_swappable<_Tp>::value);
2692
2693 /// @cond undocumented
2694 namespace __swappable_details {
2695 using std::swap;
2696
2697 struct __do_is_swappable_impl
2698 {
2699 template<typename _Tp, typename
2700 = decltype(swap(std::declval<_Tp&>(), std::declval<_Tp&>()))>
2701 static true_type __test(int);
2702
2703 template<typename>
2704 static false_type __test(...);
2705 };
2706
2707 struct __do_is_nothrow_swappable_impl
2708 {
2709 template<typename _Tp>
2710 static __bool_constant<
2711 noexcept(swap(std::declval<_Tp&>(), std::declval<_Tp&>()))
2712 > __test(int);
2713
2714 template<typename>
2715 static false_type __test(...);
2716 };
2717
2718 } // namespace __swappable_details
2719
2720 template<typename _Tp>
2721 struct __is_swappable_impl
2722 : public __swappable_details::__do_is_swappable_impl
2723 {
2724 typedef decltype(__test<_Tp>(0)) type;
2725 };
2726
2727 template<typename _Tp>
2728 struct __is_nothrow_swappable_impl
2729 : public __swappable_details::__do_is_nothrow_swappable_impl
2730 {
2731 typedef decltype(__test<_Tp>(0)) type;
2732 };
2733
2734 template<typename _Tp>
2735 struct __is_swappable
2736 : public __is_swappable_impl<_Tp>::type
2737 { };
2738
2739 template<typename _Tp>
2740 struct __is_nothrow_swappable
2741 : public __is_nothrow_swappable_impl<_Tp>::type
2742 { };
2743 /// @endcond
2744
2745#if __cplusplus > 201402L || !defined(__STRICT_ANSI__) // c++1z or gnu++11
2746#define __cpp_lib_is_swappable 201603
2747 /// Metafunctions used for detecting swappable types: p0185r1
2748
2749 /// is_swappable
2750 template<typename _Tp>
2751 struct is_swappable
2752 : public __is_swappable_impl<_Tp>::type
2753 {
2754 static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
2755 "template argument must be a complete class or an unbounded array");
2756 };
2757
2758 /// is_nothrow_swappable
2759 template<typename _Tp>
2760 struct is_nothrow_swappable
2761 : public __is_nothrow_swappable_impl<_Tp>::type
2762 {
2763 static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
2764 "template argument must be a complete class or an unbounded array");
2765 };
2766
2767#if __cplusplus >= 201402L
2768 /// is_swappable_v
2769 template<typename _Tp>
2770 _GLIBCXX17_INLINE constexpr bool is_swappable_v =
2771 is_swappable<_Tp>::value;
2772
2773 /// is_nothrow_swappable_v
2774 template<typename _Tp>
2775 _GLIBCXX17_INLINE constexpr bool is_nothrow_swappable_v =
2776 is_nothrow_swappable<_Tp>::value;
2777#endif // __cplusplus >= 201402L
2778
2779 /// @cond undocumented
2780 namespace __swappable_with_details {
2781 using std::swap;
2782
2783 struct __do_is_swappable_with_impl
2784 {
2785 template<typename _Tp, typename _Up, typename
2786 = decltype(swap(std::declval<_Tp>(), std::declval<_Up>())),
2787 typename
2788 = decltype(swap(std::declval<_Up>(), std::declval<_Tp>()))>
2789 static true_type __test(int);
2790
2791 template<typename, typename>
2792 static false_type __test(...);
2793 };
2794
2795 struct __do_is_nothrow_swappable_with_impl
2796 {
2797 template<typename _Tp, typename _Up>
2798 static __bool_constant<
2799 noexcept(swap(std::declval<_Tp>(), std::declval<_Up>()))
2800 &&
2801 noexcept(swap(std::declval<_Up>(), std::declval<_Tp>()))
2802 > __test(int);
2803
2804 template<typename, typename>
2805 static false_type __test(...);
2806 };
2807
2808 } // namespace __swappable_with_details
2809
2810 template<typename _Tp, typename _Up>
2811 struct __is_swappable_with_impl
2812 : public __swappable_with_details::__do_is_swappable_with_impl
2813 {
2814 typedef decltype(__test<_Tp, _Up>(0)) type;
2815 };
2816
2817 // Optimization for the homogenous lvalue case, not required:
2818 template<typename _Tp>
2819 struct __is_swappable_with_impl<_Tp&, _Tp&>
2820 : public __swappable_details::__do_is_swappable_impl
2821 {
2822 typedef decltype(__test<_Tp&>(0)) type;
2823 };
2824
2825 template<typename _Tp, typename _Up>
2826 struct __is_nothrow_swappable_with_impl
2827 : public __swappable_with_details::__do_is_nothrow_swappable_with_impl
2828 {
2829 typedef decltype(__test<_Tp, _Up>(0)) type;
2830 };
2831
2832 // Optimization for the homogenous lvalue case, not required:
2833 template<typename _Tp>
2834 struct __is_nothrow_swappable_with_impl<_Tp&, _Tp&>
2835 : public __swappable_details::__do_is_nothrow_swappable_impl
2836 {
2837 typedef decltype(__test<_Tp&>(0)) type;
2838 };
2839 /// @endcond
2840
2841 /// is_swappable_with
2842 template<typename _Tp, typename _Up>
2843 struct is_swappable_with
2844 : public __is_swappable_with_impl<_Tp, _Up>::type
2845 {
2846 static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
2847 "first template argument must be a complete class or an unbounded array");
2848 static_assert(std::__is_complete_or_unbounded(__type_identity<_Up>{}),
2849 "second template argument must be a complete class or an unbounded array");
2850 };
2851
2852 /// is_nothrow_swappable_with
2853 template<typename _Tp, typename _Up>
2854 struct is_nothrow_swappable_with
2855 : public __is_nothrow_swappable_with_impl<_Tp, _Up>::type
2856 {
2857 static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
2858 "first template argument must be a complete class or an unbounded array");
2859 static_assert(std::__is_complete_or_unbounded(__type_identity<_Up>{}),
2860 "second template argument must be a complete class or an unbounded array");
2861 };
2862
2863#if __cplusplus >= 201402L
2864 /// is_swappable_with_v
2865 template<typename _Tp, typename _Up>
2866 _GLIBCXX17_INLINE constexpr bool is_swappable_with_v =
2867 is_swappable_with<_Tp, _Up>::value;
2868
2869 /// is_nothrow_swappable_with_v
2870 template<typename _Tp, typename _Up>
2871 _GLIBCXX17_INLINE constexpr bool is_nothrow_swappable_with_v =
2872 is_nothrow_swappable_with<_Tp, _Up>::value;
2873#endif // __cplusplus >= 201402L
2874
2875#endif// c++1z or gnu++11
2876
2877 /// @cond undocumented
2878
2879 // __is_invocable (std::is_invocable for C++11)
2880
2881 // The primary template is used for invalid INVOKE expressions.
2882 template<typename _Result, typename _Ret,
2883 bool = is_void<_Ret>::value, typename = void>
2884 struct __is_invocable_impl : false_type { };
2885
2886 // Used for valid INVOKE and INVOKE<void> expressions.
2887 template<typename _Result, typename _Ret>
2888 struct __is_invocable_impl<_Result, _Ret,
2889 /* is_void<_Ret> = */ true,
2890 __void_t<typename _Result::type>>
2891 : true_type
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.
2905 static typename _Result::type _S_get();
2906
2907 template<typename _Tp>
2908 static void _S_conv(_Tp);
2909
2910 // This overload is viable if INVOKE(f, args...) can convert to _Tp.
2911 template<typename _Tp, typename = decltype(_S_conv<_Tp>(_S_get()))>
2912 static true_type
2913 _S_test(int);
2914
2915 template<typename _Tp>
2916 static false_type
2917 _S_test(...);
2918
2919 public:
2920 using type = decltype(_S_test<_Ret>(1));
2921 };
2922#pragma GCC diagnostic pop
2923
2924 template<typename _Fn, typename... _ArgTypes>
2925 struct __is_invocable
2926 : __is_invocable_impl<__invoke_result<_Fn, _ArgTypes...>, void>::type
2927 { };
2928
2929 template<typename _Fn, typename _Tp, typename... _Args>
2930 constexpr bool __call_is_nt(__invoke_memfun_ref)
2931 {
2932 using _Up = typename __inv_unwrap<_Tp>::type;
2933 return noexcept((std::declval<_Up>().*std::declval<_Fn>())(
2934 std::declval<_Args>()...));
2935 }
2936
2937 template<typename _Fn, typename _Tp, typename... _Args>
2938 constexpr bool __call_is_nt(__invoke_memfun_deref)
2939 {
2940 return noexcept(((*std::declval<_Tp>()).*std::declval<_Fn>())(
2941 std::declval<_Args>()...));
2942 }
2943
2944 template<typename _Fn, typename _Tp>
2945 constexpr bool __call_is_nt(__invoke_memobj_ref)
2946 {
2947 using _Up = typename __inv_unwrap<_Tp>::type;
2948 return noexcept(std::declval<_Up>().*std::declval<_Fn>());
2949 }
2950
2951 template<typename _Fn, typename _Tp>
2952 constexpr bool __call_is_nt(__invoke_memobj_deref)
2953 {
2954 return noexcept((*std::declval<_Tp>()).*std::declval<_Fn>());
2955 }
2956
2957 template<typename _Fn, typename... _Args>
2958 constexpr bool __call_is_nt(__invoke_other)
2959 {
2960 return noexcept(std::declval<_Fn>()(std::declval<_Args>()...));
2961 }
2962
2963 template<typename _Result, typename _Fn, typename... _Args>
2964 struct __call_is_nothrow
2965 : __bool_constant<
2966 std::__call_is_nt<_Fn, _Args...>(typename _Result::__invoke_type{})
2967 >
2968 { };
2969
2970 template<typename _Fn, typename... _Args>
2971 using __call_is_nothrow_
2972 = __call_is_nothrow<__invoke_result<_Fn, _Args...>, _Fn, _Args...>;
2973
2974 // __is_nothrow_invocable (std::is_nothrow_invocable for C++11)
2975 template<typename _Fn, typename... _Args>
2976 struct __is_nothrow_invocable
2977 : __and_<__is_invocable<_Fn, _Args...>,
2978 __call_is_nothrow_<_Fn, _Args...>>::type
2979 { };
2980
2981#pragma GCC diagnostic push
2982#pragma GCC diagnostic ignored "-Wctor-dtor-privacy"
2983 struct __nonesuchbase {};
2984 struct __nonesuch : private __nonesuchbase {
2985 ~__nonesuch() = delete;
2986 __nonesuch(__nonesuch const&) = delete;
2987 void operator=(__nonesuch const&) = delete;
2988 };
2989#pragma GCC diagnostic pop
2990 /// @endcond
2991
2992#if __cplusplus >= 201703L
2993# define __cpp_lib_is_invocable 201703
2994
2995 /// std::invoke_result
2996 template<typename _Functor, typename... _ArgTypes>
2997 struct invoke_result
2998 : public __invoke_result<_Functor, _ArgTypes...>
2999 {
3000 static_assert(std::__is_complete_or_unbounded(__type_identity<_Functor>{}),
3001 "_Functor must be a complete class or an unbounded array");
3002 static_assert((std::__is_complete_or_unbounded(
3003 __type_identity<_ArgTypes>{}) && ...),
3004 "each argument type must be a complete class or an unbounded array");
3005 };
3006
3007 /// std::invoke_result_t
3008 template<typename _Fn, typename... _Args>
3009 using invoke_result_t = typename invoke_result<_Fn, _Args...>::type;
3010
3011 /// std::is_invocable
3012 template<typename _Fn, typename... _ArgTypes>
3013 struct is_invocable
3014 : __is_invocable_impl<__invoke_result<_Fn, _ArgTypes...>, void>::type
3015 {
3016 static_assert(std::__is_complete_or_unbounded(__type_identity<_Fn>{}),
3017 "_Fn must be a complete class or an unbounded array");
3018 static_assert((std::__is_complete_or_unbounded(
3019 __type_identity<_ArgTypes>{}) && ...),
3020 "each argument type must be a complete class or an unbounded array");
3021 };
3022
3023 /// std::is_invocable_r
3024 template<typename _Ret, typename _Fn, typename... _ArgTypes>
3025 struct is_invocable_r
3026 : __is_invocable_impl<__invoke_result<_Fn, _ArgTypes...>, _Ret>::type
3027 {
3028 static_assert(std::__is_complete_or_unbounded(__type_identity<_Fn>{}),
3029 "_Fn must be a complete class or an unbounded array");
3030 static_assert((std::__is_complete_or_unbounded(
3031 __type_identity<_ArgTypes>{}) && ...),
3032 "each argument type must be a complete class or an unbounded array");
3033 static_assert(std::__is_complete_or_unbounded(__type_identity<_Ret>{}),
3034 "_Ret must be a complete class or an unbounded array");
3035 };
3036
3037 /// std::is_nothrow_invocable
3038 template<typename _Fn, typename... _ArgTypes>
3039 struct is_nothrow_invocable
3040 : __and_<__is_invocable_impl<__invoke_result<_Fn, _ArgTypes...>, void>,
3041 __call_is_nothrow_<_Fn, _ArgTypes...>>::type
3042 {
3043 static_assert(std::__is_complete_or_unbounded(__type_identity<_Fn>{}),
3044 "_Fn must be a complete class or an unbounded array");
3045 static_assert((std::__is_complete_or_unbounded(
3046 __type_identity<_ArgTypes>{}) && ...),
3047 "each argument type must be a complete class or an unbounded array");
3048 };
3049
3050 /// @cond undocumented
3051 template<typename _Result, typename _Ret, typename = void>
3052 struct __is_nt_invocable_impl : false_type { };
3053
3054 template<typename _Result, typename _Ret>
3055 struct __is_nt_invocable_impl<_Result, _Ret,
3056 __void_t<typename _Result::type>>
3057 : __or_<is_void<_Ret>,
3058 __is_nothrow_convertible<typename _Result::type, _Ret>>
3059 { };
3060 /// @endcond
3061
3062 /// std::is_nothrow_invocable_r
3063 template<typename _Ret, typename _Fn, typename... _ArgTypes>
3064 struct is_nothrow_invocable_r
3065 : __and_<__is_nt_invocable_impl<__invoke_result<_Fn, _ArgTypes...>, _Ret>,
3066 __call_is_nothrow_<_Fn, _ArgTypes...>>::type
3067 {
3068 static_assert(std::__is_complete_or_unbounded(__type_identity<_Fn>{}),
3069 "_Fn must be a complete class or an unbounded array");
3070 static_assert((std::__is_complete_or_unbounded(
3071 __type_identity<_ArgTypes>{}) && ...),
3072 "each argument type must be a complete class or an unbounded array");
3073 static_assert(std::__is_complete_or_unbounded(__type_identity<_Ret>{}),
3074 "_Ret must be a complete class or an unbounded array");
3075 };
3076#endif // C++17
3077
3078#if __cplusplus >= 201703L
3079# define __cpp_lib_type_trait_variable_templates 201510L
3080 /**
3081 * @defgroup variable_templates Variable templates for type traits.
3082 * @ingroup metaprogramming
3083 *
3084 * The variable `is_foo_v<T>` is a boolean constant with the same value
3085 * as the type trait `is_foo<T>::value`.
3086 *
3087 * @since C++17
3088 */
3089
3090 /** @ingroup variable_templates
3091 * @{
3092 */
3093template <typename _Tp>
3094 inline constexpr bool is_void_v = is_void<_Tp>::value;
3095template <typename _Tp>
3096 inline constexpr bool is_null_pointer_v = is_null_pointer<_Tp>::value;
3097template <typename _Tp>
3098 inline constexpr bool is_integral_v = is_integral<_Tp>::value;
3099template <typename _Tp>
3100 inline constexpr bool is_floating_point_v = is_floating_point<_Tp>::value;
3101template <typename _Tp>
3102 inline constexpr bool is_array_v = is_array<_Tp>::value;
3103template <typename _Tp>
3104 inline constexpr bool is_pointer_v = is_pointer<_Tp>::value;
3105template <typename _Tp>
3106 inline constexpr bool is_lvalue_reference_v =
3107 is_lvalue_reference<_Tp>::value;
3108template <typename _Tp>
3109 inline constexpr bool is_rvalue_reference_v =
3110 is_rvalue_reference<_Tp>::value;
3111template <typename _Tp>
3112 inline constexpr bool is_member_object_pointer_v =
3113 is_member_object_pointer<_Tp>::value;
3114template <typename _Tp>
3115 inline constexpr bool is_member_function_pointer_v =
3116 is_member_function_pointer<_Tp>::value;
3117template <typename _Tp>
3118 inline constexpr bool is_enum_v = is_enum<_Tp>::value;
3119template <typename _Tp>
3120 inline constexpr bool is_union_v = is_union<_Tp>::value;
3121template <typename _Tp>
3122 inline constexpr bool is_class_v = is_class<_Tp>::value;
3123template <typename _Tp>
3124 inline constexpr bool is_function_v = is_function<_Tp>::value;
3125template <typename _Tp>
3126 inline constexpr bool is_reference_v = is_reference<_Tp>::value;
3127template <typename _Tp>
3128 inline constexpr bool is_arithmetic_v = is_arithmetic<_Tp>::value;
3129template <typename _Tp>
3130 inline constexpr bool is_fundamental_v = is_fundamental<_Tp>::value;
3131template <typename _Tp>
3132 inline constexpr bool is_object_v = is_object<_Tp>::value;
3133template <typename _Tp>
3134 inline constexpr bool is_scalar_v = is_scalar<_Tp>::value;
3135template <typename _Tp>
3136 inline constexpr bool is_compound_v = is_compound<_Tp>::value;
3137template <typename _Tp>
3138 inline constexpr bool is_member_pointer_v = is_member_pointer<_Tp>::value;
3139template <typename _Tp>
3140 inline constexpr bool is_const_v = is_const<_Tp>::value;
3141template <typename _Tp>
3142 inline constexpr bool is_volatile_v = is_volatile<_Tp>::value;
3143template <typename _Tp>
3144 inline constexpr bool is_trivial_v = is_trivial<_Tp>::value;
3145template <typename _Tp>
3146 inline constexpr bool is_trivially_copyable_v =
3147 is_trivially_copyable<_Tp>::value;
3148template <typename _Tp>
3149 inline constexpr bool is_standard_layout_v = is_standard_layout<_Tp>::value;
3150#pragma GCC diagnostic push
3151#pragma GCC diagnostic ignored "-Wdeprecated-declarations"
3152template <typename _Tp>
3153 _GLIBCXX20_DEPRECATED("use is_standard_layout_v && is_trivial_v instead")
3154 inline constexpr bool is_pod_v = is_pod<_Tp>::value;
3155template <typename _Tp>
3156 _GLIBCXX17_DEPRECATED
3157 inline constexpr bool is_literal_type_v = is_literal_type<_Tp>::value;
3158#pragma GCC diagnostic pop
3159 template <typename _Tp>
3160 inline constexpr bool is_empty_v = is_empty<_Tp>::value;
3161template <typename _Tp>
3162 inline constexpr bool is_polymorphic_v = is_polymorphic<_Tp>::value;
3163template <typename _Tp>
3164 inline constexpr bool is_abstract_v = is_abstract<_Tp>::value;
3165template <typename _Tp>
3166 inline constexpr bool is_final_v = is_final<_Tp>::value;
3167template <typename _Tp>
3168 inline constexpr bool is_signed_v = is_signed<_Tp>::value;
3169template <typename _Tp>
3170 inline constexpr bool is_unsigned_v = is_unsigned<_Tp>::value;
3171template <typename _Tp, typename... _Args>
3172 inline constexpr bool is_constructible_v =
3173 is_constructible<_Tp, _Args...>::value;
3174template <typename _Tp>
3175 inline constexpr bool is_default_constructible_v =
3176 is_default_constructible<_Tp>::value;
3177template <typename _Tp>
3178 inline constexpr bool is_copy_constructible_v =
3179 is_copy_constructible<_Tp>::value;
3180template <typename _Tp>
3181 inline constexpr bool is_move_constructible_v =
3182 is_move_constructible<_Tp>::value;
3183template <typename _Tp, typename _Up>
3184 inline constexpr bool is_assignable_v = is_assignable<_Tp, _Up>::value;
3185template <typename _Tp>
3186 inline constexpr bool is_copy_assignable_v = is_copy_assignable<_Tp>::value;
3187template <typename _Tp>
3188 inline constexpr bool is_move_assignable_v = is_move_assignable<_Tp>::value;
3189template <typename _Tp>
3190 inline constexpr bool is_destructible_v = is_destructible<_Tp>::value;
3191template <typename _Tp, typename... _Args>
3192 inline constexpr bool is_trivially_constructible_v =
3193 is_trivially_constructible<_Tp, _Args...>::value;
3194template <typename _Tp>
3195 inline constexpr bool is_trivially_default_constructible_v =
3196 is_trivially_default_constructible<_Tp>::value;
3197template <typename _Tp>
3198 inline constexpr bool is_trivially_copy_constructible_v =
3199 is_trivially_copy_constructible<_Tp>::value;
3200template <typename _Tp>
3201 inline constexpr bool is_trivially_move_constructible_v =
3202 is_trivially_move_constructible<_Tp>::value;
3203template <typename _Tp, typename _Up>
3204 inline constexpr bool is_trivially_assignable_v =
3205 is_trivially_assignable<_Tp, _Up>::value;
3206template <typename _Tp>
3207 inline constexpr bool is_trivially_copy_assignable_v =
3208 is_trivially_copy_assignable<_Tp>::value;
3209template <typename _Tp>
3210 inline constexpr bool is_trivially_move_assignable_v =
3211 is_trivially_move_assignable<_Tp>::value;
3212template <typename _Tp>
3213 inline constexpr bool is_trivially_destructible_v =
3214 is_trivially_destructible<_Tp>::value;
3215template <typename _Tp, typename... _Args>
3216 inline constexpr bool is_nothrow_constructible_v =
3217 is_nothrow_constructible<_Tp, _Args...>::value;
3218template <typename _Tp>
3219 inline constexpr bool is_nothrow_default_constructible_v =
3220 is_nothrow_default_constructible<_Tp>::value;
3221template <typename _Tp>
3222 inline constexpr bool is_nothrow_copy_constructible_v =
3223 is_nothrow_copy_constructible<_Tp>::value;
3224template <typename _Tp>
3225 inline constexpr bool is_nothrow_move_constructible_v =
3226 is_nothrow_move_constructible<_Tp>::value;
3227template <typename _Tp, typename _Up>
3228 inline constexpr bool is_nothrow_assignable_v =
3229 is_nothrow_assignable<_Tp, _Up>::value;
3230template <typename _Tp>
3231 inline constexpr bool is_nothrow_copy_assignable_v =
3232 is_nothrow_copy_assignable<_Tp>::value;
3233template <typename _Tp>
3234 inline constexpr bool is_nothrow_move_assignable_v =
3235 is_nothrow_move_assignable<_Tp>::value;
3236template <typename _Tp>
3237 inline constexpr bool is_nothrow_destructible_v =
3238 is_nothrow_destructible<_Tp>::value;
3239template <typename _Tp>
3240 inline constexpr bool has_virtual_destructor_v =
3241 has_virtual_destructor<_Tp>::value;
3242template <typename _Tp>
3243 inline constexpr size_t alignment_of_v = alignment_of<_Tp>::value;
3244template <typename _Tp>
3245 inline constexpr size_t rank_v = rank<_Tp>::value;
3246template <typename _Tp, unsigned _Idx = 0>
3247 inline constexpr size_t extent_v = extent<_Tp, _Idx>::value;
3248#ifdef _GLIBCXX_HAVE_BUILTIN_IS_SAME
3249template <typename _Tp, typename _Up>
3250 inline constexpr bool is_same_v = __is_same(_Tp, _Up);
3251#else
3252template <typename _Tp, typename _Up>
3253 inline constexpr bool is_same_v = std::is_same<_Tp, _Up>::value;
3254#endif
3255template <typename _Base, typename _Derived>
3256 inline constexpr bool is_base_of_v = is_base_of<_Base, _Derived>::value;
3257template <typename _From, typename _To>
3258 inline constexpr bool is_convertible_v = is_convertible<_From, _To>::value;
3259template<typename _Fn, typename... _Args>
3260 inline constexpr bool is_invocable_v = is_invocable<_Fn, _Args...>::value;
3261template<typename _Fn, typename... _Args>
3262 inline constexpr bool is_nothrow_invocable_v
3263 = is_nothrow_invocable<_Fn, _Args...>::value;
3264template<typename _Ret, typename _Fn, typename... _Args>
3265 inline constexpr bool is_invocable_r_v
3266 = is_invocable_r<_Ret, _Fn, _Args...>::value;
3267template<typename _Ret, typename _Fn, typename... _Args>
3268 inline constexpr bool is_nothrow_invocable_r_v
3269 = is_nothrow_invocable_r<_Ret, _Fn, _Args...>::value;
3270/// @}
3271
3272#ifdef _GLIBCXX_HAVE_BUILTIN_HAS_UNIQ_OBJ_REP
3273# define __cpp_lib_has_unique_object_representations 201606
3274 /// has_unique_object_representations
3275 template<typename _Tp>
3276 struct has_unique_object_representations
3277 : bool_constant<__has_unique_object_representations(
3278 remove_cv_t<remove_all_extents_t<_Tp>>
3279 )>
3280 {
3281 static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
3282 "template argument must be a complete class or an unbounded array");
3283 };
3284
3285 /// @ingroup variable_templates
3286 template<typename _Tp>
3287 inline constexpr bool has_unique_object_representations_v
3288 = has_unique_object_representations<_Tp>::value;
3289#endif
3290
3291#ifdef _GLIBCXX_HAVE_BUILTIN_IS_AGGREGATE
3292# define __cpp_lib_is_aggregate 201703
3293 /// is_aggregate
3294 template<typename _Tp>
3295 struct is_aggregate
3296 : bool_constant<__is_aggregate(remove_cv_t<_Tp>)>
3297 { };
3298
3299 /// @ingroup variable_templates
3300 template<typename _Tp>
3301 inline constexpr bool is_aggregate_v = is_aggregate<_Tp>::value;
3302#endif
3303#endif // C++17
3304
3305#if __cplusplus > 201703L
3306#define __cpp_lib_remove_cvref 201711L
3307
3308 /// Remove references and cv-qualifiers.
3309 template<typename _Tp>
3310 struct remove_cvref
3311 : remove_cv<_Tp>
3312 { };
3313
3314 template<typename _Tp>
3315 struct remove_cvref<_Tp&>
3316 : remove_cv<_Tp>
3317 { };
3318
3319 template<typename _Tp>
3320 struct remove_cvref<_Tp&&>
3321 : remove_cv<_Tp>
3322 { };
3323
3324 template<typename _Tp>
3325 using remove_cvref_t = typename remove_cvref<_Tp>::type;
3326
3327#define __cpp_lib_type_identity 201806L
3328 /// Identity metafunction.
3329 template<typename _Tp>
3330 struct type_identity { using type = _Tp; };
3331
3332 template<typename _Tp>
3333 using type_identity_t = typename type_identity<_Tp>::type;
3334
3335#define __cpp_lib_unwrap_ref 201811L
3336
3337 /// Unwrap a reference_wrapper
3338 template<typename _Tp>
3339 struct unwrap_reference { using type = _Tp; };
3340
3341 template<typename _Tp>
3342 struct unwrap_reference<reference_wrapper<_Tp>> { using type = _Tp&; };
3343
3344 template<typename _Tp>
3345 using unwrap_reference_t = typename unwrap_reference<_Tp>::type;
3346
3347 /// Decay type and if it's a reference_wrapper, unwrap it
3348 template<typename _Tp>
3349 struct unwrap_ref_decay { using type = unwrap_reference_t<decay_t<_Tp>>; };
3350
3351 template<typename _Tp>
3352 using unwrap_ref_decay_t = typename unwrap_ref_decay<_Tp>::type;
3353
3354#define __cpp_lib_bounded_array_traits 201902L
3355
3356 /// True for a type that is an array of known bound.
3357 template<typename _Tp>
3358 struct is_bounded_array
3359 : public __is_array_known_bounds<_Tp>
3360 { };
3361
3362 /// True for a type that is an array of unknown bound.
3363 template<typename _Tp>
3364 struct is_unbounded_array
3365 : public __is_array_unknown_bounds<_Tp>
3366 { };
3367
3368 /// @ingroup variable_templates
3369 template<typename _Tp>
3370 inline constexpr bool is_bounded_array_v
3371 = is_bounded_array<_Tp>::value;
3372
3373 /// @ingroup variable_templates
3374 template<typename _Tp>
3375 inline constexpr bool is_unbounded_array_v
3376 = is_unbounded_array<_Tp>::value;
3377
3378#if __cplusplus > 202002L
3379#define __cpp_lib_is_scoped_enum 202011L
3380
3381 /// @since C++23
3382 //@{
3383
3384 template<typename _Tp>
3385 struct is_scoped_enum
3386 : false_type
3387 { };
3388
3389 template<typename _Tp>
3390 requires __is_enum(_Tp)
3391 && requires(_Tp __t) { __t = __t; } // fails if incomplete
3392 struct is_scoped_enum<_Tp>
3393 : bool_constant<!requires(_Tp __t, void(*__f)(int)) { __f(__t); }>
3394 { };
3395
3396 // FIXME remove this partial specialization and use remove_cv_t<_Tp> above
3397 // when PR c++/99968 is fixed.
3398 template<typename _Tp>
3399 requires __is_enum(_Tp)
3400 && requires(_Tp __t) { __t = __t; } // fails if incomplete
3401 struct is_scoped_enum<const _Tp>
3402 : bool_constant<!requires(_Tp __t, void(*__f)(int)) { __f(__t); }>
3403 { };
3404
3405 /**
3406 * @ingroup variable_templates
3407 */
3408 template<typename _Tp>
3409 inline constexpr bool is_scoped_enum_v = is_scoped_enum<_Tp>::value;
3410#endif // C++23
3411
3412#ifdef _GLIBCXX_HAVE_BUILTIN_IS_CONSTANT_EVALUATED
3413
3414#define __cpp_lib_is_constant_evaluated 201811L
3415
3416 /// Returns true only when called during constant evaluation.
3417 constexpr inline bool
3418 is_constant_evaluated() noexcept
3419 { return __builtin_is_constant_evaluated(); }
3420 /// @}
3421#endif
3422
3423 /// @cond undocumented
3424 template<typename _From, typename _To>
3425 using __copy_cv = typename __match_cv_qualifiers<_From, _To>::__type;
3426
3427 template<typename _Xp, typename _Yp>
3428 using __cond_res
3429 = decltype(false ? declval<_Xp(&)()>()() : declval<_Yp(&)()>()());
3430
3431 template<typename _Ap, typename _Bp, typename = void>
3432 struct __common_ref_impl
3433 { };
3434
3435 // [meta.trans.other], COMMON-REF(A, B)
3436 template<typename _Ap, typename _Bp>
3437 using __common_ref = typename __common_ref_impl<_Ap, _Bp>::type;
3438
3439 // COND-RES(COPYCV(X, Y) &, COPYCV(Y, X) &)
3440 template<typename _Xp, typename _Yp>
3441 using __condres_cvref
3442 = __cond_res<__copy_cv<_Xp, _Yp>&, __copy_cv<_Yp, _Xp>&>;
3443
3444 // If A and B are both lvalue reference types, ...
3445 template<typename _Xp, typename _Yp>
3446 struct __common_ref_impl<_Xp&, _Yp&, __void_t<__condres_cvref<_Xp, _Yp>>>
3447 : enable_if<is_reference_v<__condres_cvref<_Xp, _Yp>>,
3448 __condres_cvref<_Xp, _Yp>>
3449 { };
3450
3451 // let C be remove_reference_t<COMMON-REF(X&, Y&)>&&
3452 template<typename _Xp, typename _Yp>
3453 using __common_ref_C = remove_reference_t<__common_ref<_Xp&, _Yp&>>&&;
3454
3455 // If A and B are both rvalue reference types, ...
3456 template<typename _Xp, typename _Yp>
3457 struct __common_ref_impl<_Xp&&, _Yp&&,
3458 _Require<is_convertible<_Xp&&, __common_ref_C<_Xp, _Yp>>,
3459 is_convertible<_Yp&&, __common_ref_C<_Xp, _Yp>>>>
3460 { using type = __common_ref_C<_Xp, _Yp>; };
3461
3462 // let D be COMMON-REF(const X&, Y&)
3463 template<typename _Xp, typename _Yp>
3464 using __common_ref_D = __common_ref<const _Xp&, _Yp&>;
3465
3466 // If A is an rvalue reference and B is an lvalue reference, ...
3467 template<typename _Xp, typename _Yp>
3468 struct __common_ref_impl<_Xp&&, _Yp&,
3469 _Require<is_convertible<_Xp&&, __common_ref_D<_Xp, _Yp>>>>
3470 { using type = __common_ref_D<_Xp, _Yp>; };
3471
3472 // If A is an lvalue reference and B is an rvalue reference, ...
3473 template<typename _Xp, typename _Yp>
3474 struct __common_ref_impl<_Xp&, _Yp&&>
3475 : __common_ref_impl<_Yp&&, _Xp&>
3476 { };
3477 /// @endcond
3478
3479 template<typename _Tp, typename _Up,
3480 template<typename> class _TQual, template<typename> class _UQual>
3481 struct basic_common_reference
3482 { };
3483
3484 /// @cond undocumented
3485 template<typename _Tp>
3486 struct __xref
3487 { template<typename _Up> using __type = __copy_cv<_Tp, _Up>; };
3488
3489 template<typename _Tp>
3490 struct __xref<_Tp&>
3491 { template<typename _Up> using __type = __copy_cv<_Tp, _Up>&; };
3492
3493 template<typename _Tp>
3494 struct __xref<_Tp&&>
3495 { template<typename _Up> using __type = __copy_cv<_Tp, _Up>&&; };
3496
3497 template<typename _Tp1, typename _Tp2>
3498 using __basic_common_ref
3499 = typename basic_common_reference<remove_cvref_t<_Tp1>,
3500 remove_cvref_t<_Tp2>,
3501 __xref<_Tp1>::template __type,
3502 __xref<_Tp2>::template __type>::type;
3503 /// @endcond
3504
3505 template<typename... _Tp>
3506 struct common_reference;
3507
3508 template<typename... _Tp>
3509 using common_reference_t = typename common_reference<_Tp...>::type;
3510
3511 // If sizeof...(T) is zero, there shall be no member type.
3512 template<>
3513 struct common_reference<>
3514 { };
3515
3516 // If sizeof...(T) is one ...
3517 template<typename _Tp0>
3518 struct common_reference<_Tp0>
3519 { using type = _Tp0; };
3520
3521 /// @cond undocumented
3522 template<typename _Tp1, typename _Tp2, int _Bullet = 1, typename = void>
3523 struct __common_reference_impl
3524 : __common_reference_impl<_Tp1, _Tp2, _Bullet + 1>
3525 { };
3526
3527 // If sizeof...(T) is two ...
3528 template<typename _Tp1, typename _Tp2>
3529 struct common_reference<_Tp1, _Tp2>
3530 : __common_reference_impl<_Tp1, _Tp2>
3531 { };
3532
3533 // If T1 and T2 are reference types and COMMON-REF(T1, T2) is well-formed, ...
3534 template<typename _Tp1, typename _Tp2>
3535 struct __common_reference_impl<_Tp1&, _Tp2&, 1,
3536 void_t<__common_ref<_Tp1&, _Tp2&>>>
3537 { using type = __common_ref<_Tp1&, _Tp2&>; };
3538
3539 template<typename _Tp1, typename _Tp2>
3540 struct __common_reference_impl<_Tp1&&, _Tp2&&, 1,
3541 void_t<__common_ref<_Tp1&&, _Tp2&&>>>
3542 { using type = __common_ref<_Tp1&&, _Tp2&&>; };
3543
3544 template<typename _Tp1, typename _Tp2>
3545 struct __common_reference_impl<_Tp1&, _Tp2&&, 1,
3546 void_t<__common_ref<_Tp1&, _Tp2&&>>>
3547 { using type = __common_ref<_Tp1&, _Tp2&&>; };
3548
3549 template<typename _Tp1, typename _Tp2>
3550 struct __common_reference_impl<_Tp1&&, _Tp2&, 1,
3551 void_t<__common_ref<_Tp1&&, _Tp2&>>>
3552 { using type = __common_ref<_Tp1&&, _Tp2&>; };
3553
3554 // Otherwise, if basic_common_reference<...>::type is well-formed, ...
3555 template<typename _Tp1, typename _Tp2>
3556 struct __common_reference_impl<_Tp1, _Tp2, 2,
3557 void_t<__basic_common_ref<_Tp1, _Tp2>>>
3558 { using type = __basic_common_ref<_Tp1, _Tp2>; };
3559
3560 // Otherwise, if COND-RES(T1, T2) is well-formed, ...
3561 template<typename _Tp1, typename _Tp2>
3562 struct __common_reference_impl<_Tp1, _Tp2, 3,
3563 void_t<__cond_res<_Tp1, _Tp2>>>
3564 { using type = __cond_res<_Tp1, _Tp2>; };
3565
3566 // Otherwise, if common_type_t<T1, T2> is well-formed, ...
3567 template<typename _Tp1, typename _Tp2>
3568 struct __common_reference_impl<_Tp1, _Tp2, 4,
3569 void_t<common_type_t<_Tp1, _Tp2>>>
3570 { using type = common_type_t<_Tp1, _Tp2>; };
3571
3572 // Otherwise, there shall be no member type.
3573 template<typename _Tp1, typename _Tp2>
3574 struct __common_reference_impl<_Tp1, _Tp2, 5, void>
3575 { };
3576
3577 // Otherwise, if sizeof...(T) is greater than two, ...
3578 template<typename _Tp1, typename _Tp2, typename... _Rest>
3579 struct common_reference<_Tp1, _Tp2, _Rest...>
3580 : __common_type_fold<common_reference<_Tp1, _Tp2>,
3581 __common_type_pack<_Rest...>>
3582 { };
3583
3584 // Reuse __common_type_fold for common_reference<T1, T2, Rest...>
3585 template<typename _Tp1, typename _Tp2, typename... _Rest>
3586 struct __common_type_fold<common_reference<_Tp1, _Tp2>,
3587 __common_type_pack<_Rest...>,
3588 void_t<common_reference_t<_Tp1, _Tp2>>>
3589 : public common_reference<common_reference_t<_Tp1, _Tp2>, _Rest...>
3590 { };
3591 /// @endcond
3592
3593#endif // C++2a
3594
3595 /// @} group metaprogramming
3596
3597_GLIBCXX_END_NAMESPACE_VERSION
3598} // namespace std
3599
3600#endif // C++11
3601
3602#endif // _GLIBCXX_TYPE_TRAITS
3603