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