1// -*- C++ -*-
2//===------------------------ type_traits ---------------------------------===//
3//
4// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
5// See https://llvm.org/LICENSE.txt for license information.
6// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
7//
8//===----------------------------------------------------------------------===//
9
10#ifndef _LIBCPP_TYPE_TRAITS
11#define _LIBCPP_TYPE_TRAITS
12
13/*
14    type_traits synopsis
15
16namespace std
17{
18
19    // helper class:
20    template <class T, T v> struct integral_constant;
21    typedef integral_constant<bool, true>  true_type;   // C++11
22    typedef integral_constant<bool, false> false_type;  // C++11
23
24    template <bool B>                                   // C++14
25    using bool_constant = integral_constant<bool, B>;   // C++14
26    typedef bool_constant<true> true_type;              // C++14
27    typedef bool_constant<false> false_type;            // C++14
28
29    // helper traits
30    template <bool, class T = void> struct enable_if;
31    template <bool, class T, class F> struct conditional;
32
33    // Primary classification traits:
34    template <class T> struct is_void;
35    template <class T> struct is_null_pointer;  // C++14
36    template <class T> struct is_integral;
37    template <class T> struct is_floating_point;
38    template <class T> struct is_array;
39    template <class T> struct is_pointer;
40    template <class T> struct is_lvalue_reference;
41    template <class T> struct is_rvalue_reference;
42    template <class T> struct is_member_object_pointer;
43    template <class T> struct is_member_function_pointer;
44    template <class T> struct is_enum;
45    template <class T> struct is_union;
46    template <class T> struct is_class;
47    template <class T> struct is_function;
48
49    // Secondary classification traits:
50    template <class T> struct is_reference;
51    template <class T> struct is_arithmetic;
52    template <class T> struct is_fundamental;
53    template <class T> struct is_member_pointer;
54    template <class T> struct is_scalar;
55    template <class T> struct is_object;
56    template <class T> struct is_compound;
57
58    // Const-volatile properties and transformations:
59    template <class T> struct is_const;
60    template <class T> struct is_volatile;
61    template <class T> struct remove_const;
62    template <class T> struct remove_volatile;
63    template <class T> struct remove_cv;
64    template <class T> struct add_const;
65    template <class T> struct add_volatile;
66    template <class T> struct add_cv;
67
68    // Reference transformations:
69    template <class T> struct remove_reference;
70    template <class T> struct add_lvalue_reference;
71    template <class T> struct add_rvalue_reference;
72
73    // Pointer transformations:
74    template <class T> struct remove_pointer;
75    template <class T> struct add_pointer;
76
77    template<class T> struct type_identity;                     // C++20
78    template<class T>
79      using type_identity_t = typename type_identity<T>::type;  // C++20
80
81    // Integral properties:
82    template <class T> struct is_signed;
83    template <class T> struct is_unsigned;
84    template <class T> struct make_signed;
85    template <class T> struct make_unsigned;
86
87    // Array properties and transformations:
88    template <class T> struct rank;
89    template <class T, unsigned I = 0> struct extent;
90    template <class T> struct remove_extent;
91    template <class T> struct remove_all_extents;
92
93    template <class T> struct is_bounded_array;                 // C++20
94    template <class T> struct is_unbounded_array;               // C++20
95
96    // Member introspection:
97    template <class T> struct is_pod;
98    template <class T> struct is_trivial;
99    template <class T> struct is_trivially_copyable;
100    template <class T> struct is_standard_layout;
101    template <class T> struct is_literal_type;
102    template <class T> struct is_empty;
103    template <class T> struct is_polymorphic;
104    template <class T> struct is_abstract;
105    template <class T> struct is_final; // C++14
106    template <class T> struct is_aggregate; // C++17
107
108    template <class T, class... Args> struct is_constructible;
109    template <class T>                struct is_default_constructible;
110    template <class T>                struct is_copy_constructible;
111    template <class T>                struct is_move_constructible;
112    template <class T, class U>       struct is_assignable;
113    template <class T>                struct is_copy_assignable;
114    template <class T>                struct is_move_assignable;
115    template <class T, class U>       struct is_swappable_with;       // C++17
116    template <class T>                struct is_swappable;            // C++17
117    template <class T>                struct is_destructible;
118
119    template <class T, class... Args> struct is_trivially_constructible;
120    template <class T>                struct is_trivially_default_constructible;
121    template <class T>                struct is_trivially_copy_constructible;
122    template <class T>                struct is_trivially_move_constructible;
123    template <class T, class U>       struct is_trivially_assignable;
124    template <class T>                struct is_trivially_copy_assignable;
125    template <class T>                struct is_trivially_move_assignable;
126    template <class T>                struct is_trivially_destructible;
127
128    template <class T, class... Args> struct is_nothrow_constructible;
129    template <class T>                struct is_nothrow_default_constructible;
130    template <class T>                struct is_nothrow_copy_constructible;
131    template <class T>                struct is_nothrow_move_constructible;
132    template <class T, class U>       struct is_nothrow_assignable;
133    template <class T>                struct is_nothrow_copy_assignable;
134    template <class T>                struct is_nothrow_move_assignable;
135    template <class T, class U>       struct is_nothrow_swappable_with; // C++17
136    template <class T>                struct is_nothrow_swappable;      // C++17
137    template <class T>                struct is_nothrow_destructible;
138
139    template <class T> struct has_virtual_destructor;
140
141    template<class T> struct has_unique_object_representations;         // C++17
142
143    // Relationships between types:
144    template <class T, class U> struct is_same;
145    template <class Base, class Derived> struct is_base_of;
146
147    template <class From, class To> struct is_convertible;
148    template <typename From, typename To> struct is_nothrow_convertible;                  // C++20
149    template <typename From, typename To> inline constexpr bool is_nothrow_convertible_v; // C++20
150
151    template <class Fn, class... ArgTypes> struct is_invocable;
152    template <class R, class Fn, class... ArgTypes> struct is_invocable_r;
153
154    template <class Fn, class... ArgTypes> struct is_nothrow_invocable;
155    template <class R, class Fn, class... ArgTypes> struct is_nothrow_invocable_r;
156
157    // Alignment properties and transformations:
158    template <class T> struct alignment_of;
159    template <size_t Len, size_t Align = most_stringent_alignment_requirement>
160        struct aligned_storage;
161    template <size_t Len, class... Types> struct aligned_union;
162    template <class T> struct remove_cvref; // C++20
163
164    template <class T> struct decay;
165    template <class... T> struct common_type;
166    template <class T> struct underlying_type;
167    template <class> class result_of; // undefined
168    template <class Fn, class... ArgTypes> class result_of<Fn(ArgTypes...)>;
169    template <class Fn, class... ArgTypes> struct invoke_result;  // C++17
170
171    // const-volatile modifications:
172    template <class T>
173      using remove_const_t    = typename remove_const<T>::type;  // C++14
174    template <class T>
175      using remove_volatile_t = typename remove_volatile<T>::type;  // C++14
176    template <class T>
177      using remove_cv_t       = typename remove_cv<T>::type;  // C++14
178    template <class T>
179      using add_const_t       = typename add_const<T>::type;  // C++14
180    template <class T>
181      using add_volatile_t    = typename add_volatile<T>::type;  // C++14
182    template <class T>
183      using add_cv_t          = typename add_cv<T>::type;  // C++14
184
185    // reference modifications:
186    template <class T>
187      using remove_reference_t     = typename remove_reference<T>::type;  // C++14
188    template <class T>
189      using add_lvalue_reference_t = typename add_lvalue_reference<T>::type;  // C++14
190    template <class T>
191      using add_rvalue_reference_t = typename add_rvalue_reference<T>::type;  // C++14
192
193    // sign modifications:
194    template <class T>
195      using make_signed_t   = typename make_signed<T>::type;  // C++14
196    template <class T>
197      using make_unsigned_t = typename make_unsigned<T>::type;  // C++14
198
199    // array modifications:
200    template <class T>
201      using remove_extent_t      = typename remove_extent<T>::type;  // C++14
202    template <class T>
203      using remove_all_extents_t = typename remove_all_extents<T>::type;  // C++14
204
205    template <class T>
206      inline constexpr bool is_bounded_array_v
207        = is_bounded_array<T>::value;                                     // C++20
208      inline constexpr bool is_unbounded_array_v
209        = is_unbounded_array<T>::value;                                   // C++20
210
211    // pointer modifications:
212    template <class T>
213      using remove_pointer_t = typename remove_pointer<T>::type;  // C++14
214    template <class T>
215      using add_pointer_t    = typename add_pointer<T>::type;  // C++14
216
217    // other transformations:
218    template <size_t Len, std::size_t Align=default-alignment>
219      using aligned_storage_t = typename aligned_storage<Len,Align>::type;  // C++14
220    template <std::size_t Len, class... Types>
221      using aligned_union_t   = typename aligned_union<Len,Types...>::type;  // C++14
222    template <class T>
223      using remove_cvref_t    = typename remove_cvref<T>::type;  // C++20
224    template <class T>
225      using decay_t           = typename decay<T>::type;  // C++14
226    template <bool b, class T=void>
227      using enable_if_t       = typename enable_if<b,T>::type;  // C++14
228    template <bool b, class T, class F>
229      using conditional_t     = typename conditional<b,T,F>::type;  // C++14
230    template <class... T>
231      using common_type_t     = typename common_type<T...>::type;  // C++14
232    template <class T>
233      using underlying_type_t = typename underlying_type<T>::type;  // C++14
234    template <class T>
235      using result_of_t       = typename result_of<T>::type;  // C++14
236    template <class Fn, class... ArgTypes>
237      using invoke_result_t   = typename invoke_result<Fn, ArgTypes...>::type;  // C++17
238
239    template <class...>
240      using void_t = void;   // C++17
241
242      // See C++14 20.10.4.1, primary type categories
243      template <class T> inline constexpr bool is_void_v
244        = is_void<T>::value;                                             // C++17
245      template <class T> inline constexpr bool is_null_pointer_v
246        = is_null_pointer<T>::value;                                     // C++17
247      template <class T> inline constexpr bool is_integral_v
248        = is_integral<T>::value;                                         // C++17
249      template <class T> inline constexpr bool is_floating_point_v
250        = is_floating_point<T>::value;                                   // C++17
251      template <class T> inline constexpr bool is_array_v
252        = is_array<T>::value;                                            // C++17
253      template <class T> inline constexpr bool is_pointer_v
254        = is_pointer<T>::value;                                          // C++17
255      template <class T> inline constexpr bool is_lvalue_reference_v
256        = is_lvalue_reference<T>::value;                                 // C++17
257      template <class T> inline constexpr bool is_rvalue_reference_v
258        = is_rvalue_reference<T>::value;                                 // C++17
259      template <class T> inline constexpr bool is_member_object_pointer_v
260        = is_member_object_pointer<T>::value;                            // C++17
261      template <class T> inline constexpr bool is_member_function_pointer_v
262        = is_member_function_pointer<T>::value;                          // C++17
263      template <class T> inline constexpr bool is_enum_v
264        = is_enum<T>::value;                                             // C++17
265      template <class T> inline constexpr bool is_union_v
266        = is_union<T>::value;                                            // C++17
267      template <class T> inline constexpr bool is_class_v
268        = is_class<T>::value;                                            // C++17
269      template <class T> inline constexpr bool is_function_v
270        = is_function<T>::value;                                         // C++17
271
272      // See C++14 20.10.4.2, composite type categories
273      template <class T> inline constexpr bool is_reference_v
274        = is_reference<T>::value;                                        // C++17
275      template <class T> inline constexpr bool is_arithmetic_v
276        = is_arithmetic<T>::value;                                       // C++17
277      template <class T> inline constexpr bool is_fundamental_v
278        = is_fundamental<T>::value;                                      // C++17
279      template <class T> inline constexpr bool is_object_v
280        = is_object<T>::value;                                           // C++17
281      template <class T> inline constexpr bool is_scalar_v
282        = is_scalar<T>::value;                                           // C++17
283      template <class T> inline constexpr bool is_compound_v
284        = is_compound<T>::value;                                         // C++17
285      template <class T> inline constexpr bool is_member_pointer_v
286        = is_member_pointer<T>::value;                                   // C++17
287
288      // See C++14 20.10.4.3, type properties
289      template <class T> inline constexpr bool is_const_v
290        = is_const<T>::value;                                            // C++17
291      template <class T> inline constexpr bool is_volatile_v
292        = is_volatile<T>::value;                                         // C++17
293      template <class T> inline constexpr bool is_trivial_v
294        = is_trivial<T>::value;                                          // C++17
295      template <class T> inline constexpr bool is_trivially_copyable_v
296        = is_trivially_copyable<T>::value;                               // C++17
297      template <class T> inline constexpr bool is_standard_layout_v
298        = is_standard_layout<T>::value;                                  // C++17
299      template <class T> inline constexpr bool is_pod_v
300        = is_pod<T>::value;                                              // C++17
301      template <class T> inline constexpr bool is_literal_type_v
302        = is_literal_type<T>::value;                                     // C++17
303      template <class T> inline constexpr bool is_empty_v
304        = is_empty<T>::value;                                            // C++17
305      template <class T> inline constexpr bool is_polymorphic_v
306        = is_polymorphic<T>::value;                                      // C++17
307      template <class T> inline constexpr bool is_abstract_v
308        = is_abstract<T>::value;                                         // C++17
309      template <class T> inline constexpr bool is_final_v
310        = is_final<T>::value;                                            // C++17
311      template <class T> inline constexpr bool is_aggregate_v
312        = is_aggregate<T>::value;                                        // C++17
313      template <class T> inline constexpr bool is_signed_v
314        = is_signed<T>::value;                                           // C++17
315      template <class T> inline constexpr bool is_unsigned_v
316        = is_unsigned<T>::value;                                         // C++17
317      template <class T, class... Args> inline constexpr bool is_constructible_v
318        = is_constructible<T, Args...>::value;                           // C++17
319      template <class T> inline constexpr bool is_default_constructible_v
320        = is_default_constructible<T>::value;                            // C++17
321      template <class T> inline constexpr bool is_copy_constructible_v
322        = is_copy_constructible<T>::value;                               // C++17
323      template <class T> inline constexpr bool is_move_constructible_v
324        = is_move_constructible<T>::value;                               // C++17
325      template <class T, class U> inline constexpr bool is_assignable_v
326        = is_assignable<T, U>::value;                                    // C++17
327      template <class T> inline constexpr bool is_copy_assignable_v
328        = is_copy_assignable<T>::value;                                  // C++17
329      template <class T> inline constexpr bool is_move_assignable_v
330        = is_move_assignable<T>::value;                                  // C++17
331      template <class T, class U> inline constexpr bool is_swappable_with_v
332        = is_swappable_with<T, U>::value;                                // C++17
333      template <class T> inline constexpr bool is_swappable_v
334        = is_swappable<T>::value;                                        // C++17
335      template <class T> inline constexpr bool is_destructible_v
336        = is_destructible<T>::value;                                     // C++17
337      template <class T, class... Args> inline constexpr bool is_trivially_constructible_v
338        = is_trivially_constructible<T, Args...>::value;                 // C++17
339      template <class T> inline constexpr bool is_trivially_default_constructible_v
340        = is_trivially_default_constructible<T>::value;                  // C++17
341      template <class T> inline constexpr bool is_trivially_copy_constructible_v
342        = is_trivially_copy_constructible<T>::value;                     // C++17
343      template <class T> inline constexpr bool is_trivially_move_constructible_v
344        = is_trivially_move_constructible<T>::value;                     // C++17
345      template <class T, class U> inline constexpr bool is_trivially_assignable_v
346        = is_trivially_assignable<T, U>::value;                          // C++17
347      template <class T> inline constexpr bool is_trivially_copy_assignable_v
348        = is_trivially_copy_assignable<T>::value;                        // C++17
349      template <class T> inline constexpr bool is_trivially_move_assignable_v
350        = is_trivially_move_assignable<T>::value;                        // C++17
351      template <class T> inline constexpr bool is_trivially_destructible_v
352        = is_trivially_destructible<T>::value;                           // C++17
353      template <class T, class... Args> inline constexpr bool is_nothrow_constructible_v
354        = is_nothrow_constructible<T, Args...>::value;                   // C++17
355      template <class T> inline constexpr bool is_nothrow_default_constructible_v
356        = is_nothrow_default_constructible<T>::value;                    // C++17
357      template <class T> inline constexpr bool is_nothrow_copy_constructible_v
358        = is_nothrow_copy_constructible<T>::value;                       // C++17
359      template <class T> inline constexpr bool is_nothrow_move_constructible_v
360        = is_nothrow_move_constructible<T>::value;                       // C++17
361      template <class T, class U> inline constexpr bool is_nothrow_assignable_v
362        = is_nothrow_assignable<T, U>::value;                            // C++17
363      template <class T> inline constexpr bool is_nothrow_copy_assignable_v
364        = is_nothrow_copy_assignable<T>::value;                          // C++17
365      template <class T> inline constexpr bool is_nothrow_move_assignable_v
366        = is_nothrow_move_assignable<T>::value;                          // C++17
367      template <class T, class U> inline constexpr bool is_nothrow_swappable_with_v
368        = is_nothrow_swappable_with<T, U>::value;                       // C++17
369      template <class T> inline constexpr bool is_nothrow_swappable_v
370        = is_nothrow_swappable<T>::value;                               // C++17
371      template <class T> inline constexpr bool is_nothrow_destructible_v
372        = is_nothrow_destructible<T>::value;                             // C++17
373      template <class T> inline constexpr bool has_virtual_destructor_v
374        = has_virtual_destructor<T>::value;                              // C++17
375      template<class T> inline constexpr bool has_unique_object_representations_v // C++17
376        = has_unique_object_representations<T>::value;
377
378      // See C++14 20.10.5, type property queries
379      template <class T> inline constexpr size_t alignment_of_v
380        = alignment_of<T>::value;                                        // C++17
381      template <class T> inline constexpr size_t rank_v
382        = rank<T>::value;                                                // C++17
383      template <class T, unsigned I = 0> inline constexpr size_t extent_v
384        = extent<T, I>::value;                                           // C++17
385
386      // See C++14 20.10.6, type relations
387      template <class T, class U> inline constexpr bool is_same_v
388        = is_same<T, U>::value;                                          // C++17
389      template <class Base, class Derived> inline constexpr bool is_base_of_v
390        = is_base_of<Base, Derived>::value;                              // C++17
391      template <class From, class To> inline constexpr bool is_convertible_v
392        = is_convertible<From, To>::value;                               // C++17
393      template <class Fn, class... ArgTypes> inline constexpr bool is_invocable_v
394        = is_invocable<Fn, ArgTypes...>::value;                          // C++17
395      template <class R, class Fn, class... ArgTypes> inline constexpr bool is_invocable_r_v
396        = is_invocable_r<R, Fn, ArgTypes...>::value;                     // C++17
397      template <class Fn, class... ArgTypes> inline constexpr bool is_nothrow_invocable_v
398        = is_nothrow_invocable<Fn, ArgTypes...>::value;                  // C++17
399      template <class R, class Fn, class... ArgTypes> inline constexpr bool is_nothrow_invocable_r_v
400        = is_nothrow_invocable_r<R, Fn, ArgTypes...>::value;             // C++17
401
402      // [meta.logical], logical operator traits:
403      template<class... B> struct conjunction;                           // C++17
404      template<class... B>
405        inline constexpr bool conjunction_v = conjunction<B...>::value;  // C++17
406      template<class... B> struct disjunction;                           // C++17
407      template<class... B>
408        inline constexpr bool disjunction_v = disjunction<B...>::value;  // C++17
409      template<class B> struct negation;                                 // C++17
410      template<class B>
411        inline constexpr bool negation_v = negation<B>::value;           // C++17
412
413}
414
415*/
416#include <__config>
417#include <cstddef>
418#include <version>
419
420#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
421#pragma GCC system_header
422#endif
423
424_LIBCPP_BEGIN_NAMESPACE_STD
425
426template <class _T1, class _T2> struct _LIBCPP_TEMPLATE_VIS pair;
427template <class _Tp> class _LIBCPP_TEMPLATE_VIS reference_wrapper;
428template <class _Tp> struct _LIBCPP_TEMPLATE_VIS hash;
429
430template <class _Tp, _Tp __v>
431struct _LIBCPP_TEMPLATE_VIS integral_constant
432{
433  static _LIBCPP_CONSTEXPR const _Tp      value = __v;
434  typedef _Tp               value_type;
435  typedef integral_constant type;
436  _LIBCPP_INLINE_VISIBILITY
437  _LIBCPP_CONSTEXPR operator value_type() const _NOEXCEPT {return value;}
438#if _LIBCPP_STD_VER > 11
439  _LIBCPP_INLINE_VISIBILITY
440  constexpr value_type operator ()() const _NOEXCEPT {return value;}
441#endif
442};
443
444template <class _Tp, _Tp __v>
445_LIBCPP_CONSTEXPR const _Tp integral_constant<_Tp, __v>::value;
446
447#if _LIBCPP_STD_VER > 14
448template <bool __b>
449using bool_constant = integral_constant<bool, __b>;
450#define _LIBCPP_BOOL_CONSTANT(__b) bool_constant<(__b)>
451#else
452#define _LIBCPP_BOOL_CONSTANT(__b) integral_constant<bool,(__b)>
453#endif
454
455typedef _LIBCPP_BOOL_CONSTANT(true)  true_type;
456typedef _LIBCPP_BOOL_CONSTANT(false) false_type;
457
458template <bool _Val>
459using _BoolConstant _LIBCPP_NODEBUG_TYPE = integral_constant<bool, _Val>;
460
461template <bool> struct _MetaBase;
462template <>
463struct _MetaBase<true> {
464  template <class _Tp, class _Up>
465  using _SelectImpl _LIBCPP_NODEBUG_TYPE = _Tp;
466  template <template <class...> class _FirstFn, template <class...> class, class ..._Args>
467  using _SelectApplyImpl _LIBCPP_NODEBUG_TYPE = _FirstFn<_Args...>;
468  template <class _First, class...>
469  using _FirstImpl _LIBCPP_NODEBUG_TYPE = _First;
470  template <class, class _Second, class...>
471  using _SecondImpl _LIBCPP_NODEBUG_TYPE = _Second;
472  template <class _Tp = void>
473  using _EnableIfImpl _LIBCPP_NODEBUG_TYPE = _Tp;
474  template <class _Result, class _First, class ..._Rest>
475  using _OrImpl _LIBCPP_NODEBUG_TYPE = typename _MetaBase<_First::value != true && sizeof...(_Rest) != 0>::template _OrImpl<_First, _Rest...>;
476  template <class _Result, class _First, class ..._Rest>
477  using _AndImpl _LIBCPP_NODEBUG_TYPE = typename _MetaBase<_First::value == true && sizeof...(_Rest) != 0>::template _AndImpl<_First, _Rest...>;
478};
479
480template <>
481struct _MetaBase<false> {
482  template <class _Tp, class _Up>
483  using _SelectImpl _LIBCPP_NODEBUG_TYPE = _Up;
484  template <template <class...> class, template <class...> class _SecondFn, class ..._Args>
485  using _SelectApplyImpl _LIBCPP_NODEBUG_TYPE = _SecondFn<_Args...>;
486  template <class _Result, class ...>
487  using _OrImpl _LIBCPP_NODEBUG_TYPE = _Result;
488  template <class _Result, class ...>
489  using _AndImpl _LIBCPP_NODEBUG_TYPE = _Result;
490};
491template <bool _Cond, class _Ret = void>
492using _EnableIf _LIBCPP_NODEBUG_TYPE = typename _MetaBase<_Cond>::template _EnableIfImpl<_Ret>;
493template <bool _Cond, class _IfRes, class _ElseRes>
494using _If _LIBCPP_NODEBUG_TYPE = typename _MetaBase<_Cond>::template _SelectImpl<_IfRes, _ElseRes>;
495template <class ..._Rest>
496using _Or _LIBCPP_NODEBUG_TYPE = typename _MetaBase< sizeof...(_Rest) != 0 >::template _OrImpl<false_type, _Rest...>;
497template <class ..._Rest>
498using _And _LIBCPP_NODEBUG_TYPE = typename _MetaBase< sizeof...(_Rest) != 0 >::template _AndImpl<true_type, _Rest...>;
499template <class _Pred>
500struct _Not : _BoolConstant<!_Pred::value> {};
501template <class ..._Args>
502using _FirstType _LIBCPP_NODEBUG_TYPE = typename _MetaBase<(sizeof...(_Args) >= 1)>::template _FirstImpl<_Args...>;
503template <class ..._Args>
504using _SecondType _LIBCPP_NODEBUG_TYPE = typename _MetaBase<(sizeof...(_Args) >= 2)>::template _SecondImpl<_Args...>;
505
506template <template <class...> class _Func, class ..._Args>
507struct _Lazy : _Func<_Args...> {};
508
509// Member detector base
510
511template <template <class...> class _Templ, class ..._Args, class = _Templ<_Args...> >
512true_type __sfinae_test_impl(int);
513template <template <class...> class, class ...>
514false_type __sfinae_test_impl(...);
515
516template <template <class ...> class _Templ, class ..._Args>
517using _IsValidExpansion _LIBCPP_NODEBUG_TYPE = decltype(std::__sfinae_test_impl<_Templ, _Args...>(0));
518
519template <class>
520struct __void_t { typedef void type; };
521
522template <class _Tp>
523struct __identity { typedef _Tp type; };
524
525template <class _Tp, bool>
526struct _LIBCPP_TEMPLATE_VIS __dependent_type : public _Tp {};
527
528
529template <bool _Bp, class _If, class _Then>
530    struct _LIBCPP_TEMPLATE_VIS conditional {typedef _If type;};
531template <class _If, class _Then>
532    struct _LIBCPP_TEMPLATE_VIS conditional<false, _If, _Then> {typedef _Then type;};
533
534#if _LIBCPP_STD_VER > 11
535template <bool _Bp, class _If, class _Then> using conditional_t = typename conditional<_Bp, _If, _Then>::type;
536#endif
537
538template <bool, class _Tp = void> struct _LIBCPP_TEMPLATE_VIS enable_if {};
539template <class _Tp> struct _LIBCPP_TEMPLATE_VIS enable_if<true, _Tp> {typedef _Tp type;};
540
541#if _LIBCPP_STD_VER > 11
542template <bool _Bp, class _Tp = void> using enable_if_t = typename enable_if<_Bp, _Tp>::type;
543#endif
544
545// is_same
546
547template <class _Tp, class _Up> struct _LIBCPP_TEMPLATE_VIS is_same           : public false_type {};
548template <class _Tp>            struct _LIBCPP_TEMPLATE_VIS is_same<_Tp, _Tp> : public true_type {};
549
550#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
551template <class _Tp, class _Up>
552_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_same_v
553    = is_same<_Tp, _Up>::value;
554#endif
555
556template <class _Tp, class _Up>
557using _IsSame = _BoolConstant<
558#ifdef __clang__
559    __is_same(_Tp, _Up)
560#else
561    _VSTD::is_same<_Tp, _Up>::value
562#endif
563>;
564
565template <class _Tp, class _Up>
566using _IsNotSame = _BoolConstant<
567#ifdef __clang__
568    !__is_same(_Tp, _Up)
569#else
570    !_VSTD::is_same<_Tp, _Up>::value
571#endif
572>;
573
574
575template <class _Tp>
576using __test_for_primary_template = _EnableIf<
577    _IsSame<_Tp, typename _Tp::__primary_template>::value
578  >;
579template <class _Tp>
580using __is_primary_template = _IsValidExpansion<
581    __test_for_primary_template, _Tp
582  >;
583
584// addressof
585#ifndef _LIBCPP_HAS_NO_BUILTIN_ADDRESSOF
586
587template <class _Tp>
588inline _LIBCPP_CONSTEXPR_AFTER_CXX14
589_LIBCPP_NO_CFI _LIBCPP_INLINE_VISIBILITY
590_Tp*
591addressof(_Tp& __x) _NOEXCEPT
592{
593    return __builtin_addressof(__x);
594}
595
596#else
597
598template <class _Tp>
599inline _LIBCPP_NO_CFI _LIBCPP_INLINE_VISIBILITY
600_Tp*
601addressof(_Tp& __x) _NOEXCEPT
602{
603  return reinterpret_cast<_Tp *>(
604      const_cast<char *>(&reinterpret_cast<const volatile char &>(__x)));
605}
606
607#endif // _LIBCPP_HAS_NO_BUILTIN_ADDRESSOF
608
609#if defined(_LIBCPP_HAS_OBJC_ARC) && !defined(_LIBCPP_PREDEFINED_OBJC_ARC_ADDRESSOF)
610// Objective-C++ Automatic Reference Counting uses qualified pointers
611// that require special addressof() signatures. When
612// _LIBCPP_PREDEFINED_OBJC_ARC_ADDRESSOF is defined, the compiler
613// itself is providing these definitions. Otherwise, we provide them.
614template <class _Tp>
615inline _LIBCPP_INLINE_VISIBILITY
616__strong _Tp*
617addressof(__strong _Tp& __x) _NOEXCEPT
618{
619  return &__x;
620}
621
622#ifdef _LIBCPP_HAS_OBJC_ARC_WEAK
623template <class _Tp>
624inline _LIBCPP_INLINE_VISIBILITY
625__weak _Tp*
626addressof(__weak _Tp& __x) _NOEXCEPT
627{
628  return &__x;
629}
630#endif
631
632template <class _Tp>
633inline _LIBCPP_INLINE_VISIBILITY
634__autoreleasing _Tp*
635addressof(__autoreleasing _Tp& __x) _NOEXCEPT
636{
637  return &__x;
638}
639
640template <class _Tp>
641inline _LIBCPP_INLINE_VISIBILITY
642__unsafe_unretained _Tp*
643addressof(__unsafe_unretained _Tp& __x) _NOEXCEPT
644{
645  return &__x;
646}
647#endif
648
649#if !defined(_LIBCPP_CXX03_LANG)
650template <class _Tp> _Tp* addressof(const _Tp&&) noexcept = delete;
651#endif
652
653struct __two {char __lx[2];};
654
655// helper class:
656
657// is_const
658
659template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_const            : public false_type {};
660template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_const<_Tp const> : public true_type {};
661
662#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
663template <class _Tp>
664_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_const_v
665    = is_const<_Tp>::value;
666#endif
667
668// is_volatile
669
670template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_volatile               : public false_type {};
671template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_volatile<_Tp volatile> : public true_type {};
672
673#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
674template <class _Tp>
675_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_volatile_v
676    = is_volatile<_Tp>::value;
677#endif
678
679// remove_const
680
681template <class _Tp> struct _LIBCPP_TEMPLATE_VIS remove_const            {typedef _Tp type;};
682template <class _Tp> struct _LIBCPP_TEMPLATE_VIS remove_const<const _Tp> {typedef _Tp type;};
683#if _LIBCPP_STD_VER > 11
684template <class _Tp> using remove_const_t = typename remove_const<_Tp>::type;
685#endif
686
687// remove_volatile
688
689template <class _Tp> struct _LIBCPP_TEMPLATE_VIS remove_volatile               {typedef _Tp type;};
690template <class _Tp> struct _LIBCPP_TEMPLATE_VIS remove_volatile<volatile _Tp> {typedef _Tp type;};
691#if _LIBCPP_STD_VER > 11
692template <class _Tp> using remove_volatile_t = typename remove_volatile<_Tp>::type;
693#endif
694
695// remove_cv
696
697template <class _Tp> struct _LIBCPP_TEMPLATE_VIS remove_cv
698{typedef typename remove_volatile<typename remove_const<_Tp>::type>::type type;};
699#if _LIBCPP_STD_VER > 11
700template <class _Tp> using remove_cv_t = typename remove_cv<_Tp>::type;
701#endif
702
703// is_void
704
705template <class _Tp> struct __libcpp_is_void       : public false_type {};
706template <>          struct __libcpp_is_void<void> : public true_type {};
707
708template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_void
709    : public __libcpp_is_void<typename remove_cv<_Tp>::type> {};
710
711#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
712template <class _Tp>
713_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_void_v
714    = is_void<_Tp>::value;
715#endif
716
717// __is_nullptr_t
718
719template <class _Tp> struct __is_nullptr_t_impl       : public false_type {};
720template <>          struct __is_nullptr_t_impl<nullptr_t> : public true_type {};
721
722template <class _Tp> struct _LIBCPP_TEMPLATE_VIS __is_nullptr_t
723    : public __is_nullptr_t_impl<typename remove_cv<_Tp>::type> {};
724
725#if _LIBCPP_STD_VER > 11
726template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_null_pointer
727    : public __is_nullptr_t_impl<typename remove_cv<_Tp>::type> {};
728
729#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
730template <class _Tp>
731_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_null_pointer_v
732    = is_null_pointer<_Tp>::value;
733#endif
734#endif // _LIBCPP_STD_VER > 11
735
736// is_integral
737
738template <class _Tp> struct __libcpp_is_integral                     : public false_type {};
739template <>          struct __libcpp_is_integral<bool>               : public true_type {};
740template <>          struct __libcpp_is_integral<char>               : public true_type {};
741template <>          struct __libcpp_is_integral<signed char>        : public true_type {};
742template <>          struct __libcpp_is_integral<unsigned char>      : public true_type {};
743template <>          struct __libcpp_is_integral<wchar_t>            : public true_type {};
744#ifndef _LIBCPP_NO_HAS_CHAR8_T
745template <>          struct __libcpp_is_integral<char8_t>            : public true_type {};
746#endif
747#ifndef _LIBCPP_HAS_NO_UNICODE_CHARS
748template <>          struct __libcpp_is_integral<char16_t>           : public true_type {};
749template <>          struct __libcpp_is_integral<char32_t>           : public true_type {};
750#endif  // _LIBCPP_HAS_NO_UNICODE_CHARS
751template <>          struct __libcpp_is_integral<short>              : public true_type {};
752template <>          struct __libcpp_is_integral<unsigned short>     : public true_type {};
753template <>          struct __libcpp_is_integral<int>                : public true_type {};
754template <>          struct __libcpp_is_integral<unsigned int>       : public true_type {};
755template <>          struct __libcpp_is_integral<long>               : public true_type {};
756template <>          struct __libcpp_is_integral<unsigned long>      : public true_type {};
757template <>          struct __libcpp_is_integral<long long>          : public true_type {};
758template <>          struct __libcpp_is_integral<unsigned long long> : public true_type {};
759#ifndef _LIBCPP_HAS_NO_INT128
760template <>          struct __libcpp_is_integral<__int128_t>         : public true_type {};
761template <>          struct __libcpp_is_integral<__uint128_t>        : public true_type {};
762#endif
763
764template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_integral
765    : public __libcpp_is_integral<typename remove_cv<_Tp>::type> {};
766
767#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
768template <class _Tp>
769_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_integral_v
770    = is_integral<_Tp>::value;
771#endif
772
773// is_floating_point
774
775template <class _Tp> struct __libcpp_is_floating_point              : public false_type {};
776template <>          struct __libcpp_is_floating_point<float>       : public true_type {};
777template <>          struct __libcpp_is_floating_point<double>      : public true_type {};
778template <>          struct __libcpp_is_floating_point<long double> : public true_type {};
779
780template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_floating_point
781    : public __libcpp_is_floating_point<typename remove_cv<_Tp>::type> {};
782
783#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
784template <class _Tp>
785_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_floating_point_v
786    = is_floating_point<_Tp>::value;
787#endif
788
789// is_array
790
791template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_array
792    : public false_type {};
793template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_array<_Tp[]>
794    : public true_type {};
795template <class _Tp, size_t _Np> struct _LIBCPP_TEMPLATE_VIS is_array<_Tp[_Np]>
796    : public true_type {};
797
798#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
799template <class _Tp>
800_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_array_v
801    = is_array<_Tp>::value;
802#endif
803
804// is_pointer
805
806template <class _Tp> struct __libcpp_is_pointer       : public false_type {};
807template <class _Tp> struct __libcpp_is_pointer<_Tp*> : public true_type {};
808
809template <class _Tp> struct __libcpp_remove_objc_qualifiers { typedef _Tp type; };
810#if defined(_LIBCPP_HAS_OBJC_ARC)
811template <class _Tp> struct __libcpp_remove_objc_qualifiers<_Tp __strong> { typedef _Tp type; };
812template <class _Tp> struct __libcpp_remove_objc_qualifiers<_Tp __weak> { typedef _Tp type; };
813template <class _Tp> struct __libcpp_remove_objc_qualifiers<_Tp __autoreleasing> { typedef _Tp type; };
814template <class _Tp> struct __libcpp_remove_objc_qualifiers<_Tp __unsafe_unretained> { typedef _Tp type; };
815#endif
816
817template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_pointer
818    : public __libcpp_is_pointer<typename __libcpp_remove_objc_qualifiers<typename remove_cv<_Tp>::type>::type> {};
819
820#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
821template <class _Tp>
822_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_pointer_v
823    = is_pointer<_Tp>::value;
824#endif
825
826// is_reference
827
828template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_lvalue_reference       : public false_type {};
829template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_lvalue_reference<_Tp&> : public true_type {};
830
831template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_rvalue_reference        : public false_type {};
832template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_rvalue_reference<_Tp&&> : public true_type {};
833
834template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_reference        : public false_type {};
835template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_reference<_Tp&>  : public true_type {};
836template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_reference<_Tp&&> : public true_type {};
837
838#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
839template <class _Tp>
840_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_reference_v
841    = is_reference<_Tp>::value;
842
843template <class _Tp>
844_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_lvalue_reference_v
845    = is_lvalue_reference<_Tp>::value;
846
847template <class _Tp>
848_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_rvalue_reference_v
849    = is_rvalue_reference<_Tp>::value;
850#endif
851// is_union
852
853#if __has_feature(is_union) || defined(_LIBCPP_COMPILER_GCC)
854
855template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_union
856    : public integral_constant<bool, __is_union(_Tp)> {};
857
858#else
859
860template <class _Tp> struct __libcpp_union : public false_type {};
861template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_union
862    : public __libcpp_union<typename remove_cv<_Tp>::type> {};
863
864#endif
865
866#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
867template <class _Tp>
868_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_union_v
869    = is_union<_Tp>::value;
870#endif
871
872// is_class
873
874#if __has_feature(is_class) || defined(_LIBCPP_COMPILER_GCC)
875
876template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_class
877    : public integral_constant<bool, __is_class(_Tp)> {};
878
879#else
880
881namespace __is_class_imp
882{
883template <class _Tp> char  __test(int _Tp::*);
884template <class _Tp> __two __test(...);
885}
886
887template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_class
888    : public integral_constant<bool, sizeof(__is_class_imp::__test<_Tp>(0)) == 1 && !is_union<_Tp>::value> {};
889
890#endif
891
892#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
893template <class _Tp>
894_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_class_v
895    = is_class<_Tp>::value;
896#endif
897
898// is_function
899
900template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_function
901    : public _BoolConstant<
902#ifdef __clang__
903    __is_function(_Tp)
904#else
905 !(is_reference<_Tp>::value || is_const<const _Tp>::value)
906#endif
907    > {};
908
909
910#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
911template <class _Tp>
912_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_function_v
913    = is_function<_Tp>::value;
914#endif
915
916template <class _Tp> struct __libcpp_is_member_pointer {
917  enum {
918    __is_member = false,
919    __is_func = false,
920    __is_obj = false
921  };
922};
923template <class _Tp, class _Up> struct __libcpp_is_member_pointer<_Tp _Up::*> {
924  enum {
925    __is_member = true,
926    __is_func = is_function<_Tp>::value,
927    __is_obj = !__is_func,
928  };
929};
930
931
932template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_member_function_pointer
933    : public _BoolConstant< __libcpp_is_member_pointer<typename remove_cv<_Tp>::type>::__is_func > {};
934
935#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
936template <class _Tp>
937_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_member_function_pointer_v
938    = is_member_function_pointer<_Tp>::value;
939#endif
940
941// is_member_pointer
942
943template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_member_pointer
944 : public _BoolConstant< __libcpp_is_member_pointer<typename remove_cv<_Tp>::type>::__is_member > {};
945
946#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
947template <class _Tp>
948_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_member_pointer_v
949    = is_member_pointer<_Tp>::value;
950#endif
951
952// is_member_object_pointer
953
954template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_member_object_pointer
955    : public _BoolConstant< __libcpp_is_member_pointer<typename remove_cv<_Tp>::type>::__is_obj >  {};
956
957#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
958template <class _Tp>
959_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_member_object_pointer_v
960    = is_member_object_pointer<_Tp>::value;
961#endif
962
963// is_enum
964
965#if __has_feature(is_enum) || defined(_LIBCPP_COMPILER_GCC)
966
967template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_enum
968    : public integral_constant<bool, __is_enum(_Tp)> {};
969
970#else
971
972template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_enum
973    : public integral_constant<bool, !is_void<_Tp>::value             &&
974                                     !is_integral<_Tp>::value         &&
975                                     !is_floating_point<_Tp>::value   &&
976                                     !is_array<_Tp>::value            &&
977                                     !is_pointer<_Tp>::value          &&
978                                     !is_reference<_Tp>::value        &&
979                                     !is_member_pointer<_Tp>::value   &&
980                                     !is_union<_Tp>::value            &&
981                                     !is_class<_Tp>::value            &&
982                                     !is_function<_Tp>::value         > {};
983
984#endif
985
986#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
987template <class _Tp>
988_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_enum_v
989    = is_enum<_Tp>::value;
990#endif
991
992// is_arithmetic
993
994template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_arithmetic
995    : public integral_constant<bool, is_integral<_Tp>::value      ||
996                                     is_floating_point<_Tp>::value> {};
997
998#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
999template <class _Tp>
1000_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_arithmetic_v
1001    = is_arithmetic<_Tp>::value;
1002#endif
1003
1004// is_fundamental
1005
1006template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_fundamental
1007    : public integral_constant<bool, is_void<_Tp>::value        ||
1008                                     __is_nullptr_t<_Tp>::value ||
1009                                     is_arithmetic<_Tp>::value> {};
1010
1011#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
1012template <class _Tp>
1013_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_fundamental_v
1014    = is_fundamental<_Tp>::value;
1015#endif
1016
1017// is_scalar
1018
1019template <class _Tp> struct __is_block : false_type {};
1020#if defined(_LIBCPP_HAS_EXTENSION_BLOCKS)
1021template <class _Rp, class ..._Args> struct __is_block<_Rp (^)(_Args...)> : true_type {};
1022#endif
1023
1024template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_scalar
1025    : public integral_constant<bool, is_arithmetic<_Tp>::value     ||
1026                                     is_member_pointer<_Tp>::value ||
1027                                     is_pointer<_Tp>::value        ||
1028                                     __is_nullptr_t<_Tp>::value    ||
1029                                     __is_block<_Tp>::value        ||
1030                                     is_enum<_Tp>::value           > {};
1031
1032template <> struct _LIBCPP_TEMPLATE_VIS is_scalar<nullptr_t> : public true_type {};
1033
1034#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
1035template <class _Tp>
1036_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_scalar_v
1037    = is_scalar<_Tp>::value;
1038#endif
1039
1040// is_object
1041
1042template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_object
1043    : public integral_constant<bool, is_scalar<_Tp>::value ||
1044                                     is_array<_Tp>::value  ||
1045                                     is_union<_Tp>::value  ||
1046                                     is_class<_Tp>::value  > {};
1047
1048#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
1049template <class _Tp>
1050_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_object_v
1051    = is_object<_Tp>::value;
1052#endif
1053
1054// is_compound
1055
1056template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_compound
1057    : public integral_constant<bool, !is_fundamental<_Tp>::value> {};
1058
1059#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
1060template <class _Tp>
1061_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_compound_v
1062    = is_compound<_Tp>::value;
1063#endif
1064
1065
1066// __is_referenceable  [defns.referenceable]
1067
1068struct __is_referenceable_impl {
1069    template <class _Tp> static _Tp& __test(int);
1070    template <class _Tp> static __two __test(...);
1071};
1072
1073template <class _Tp>
1074struct __is_referenceable : integral_constant<bool,
1075    _IsNotSame<decltype(__is_referenceable_impl::__test<_Tp>(0)), __two>::value> {};
1076
1077
1078// add_const
1079
1080template <class _Tp> struct _LIBCPP_TEMPLATE_VIS add_const {
1081  typedef _LIBCPP_NODEBUG_TYPE const _Tp type;
1082};
1083
1084#if _LIBCPP_STD_VER > 11
1085template <class _Tp> using add_const_t = typename add_const<_Tp>::type;
1086#endif
1087
1088// add_volatile
1089
1090template <class _Tp> struct _LIBCPP_TEMPLATE_VIS add_volatile {
1091  typedef _LIBCPP_NODEBUG_TYPE volatile _Tp type;
1092};
1093
1094#if _LIBCPP_STD_VER > 11
1095template <class _Tp> using add_volatile_t = typename add_volatile<_Tp>::type;
1096#endif
1097
1098// add_cv
1099template <class _Tp> struct _LIBCPP_TEMPLATE_VIS add_cv {
1100  typedef _LIBCPP_NODEBUG_TYPE const volatile _Tp type;
1101};
1102
1103#if _LIBCPP_STD_VER > 11
1104template <class _Tp> using add_cv_t = typename add_cv<_Tp>::type;
1105#endif
1106
1107// remove_reference
1108
1109template <class _Tp> struct _LIBCPP_TEMPLATE_VIS remove_reference        {typedef _LIBCPP_NODEBUG_TYPE _Tp type;};
1110template <class _Tp> struct _LIBCPP_TEMPLATE_VIS remove_reference<_Tp&>  {typedef _LIBCPP_NODEBUG_TYPE _Tp type;};
1111template <class _Tp> struct _LIBCPP_TEMPLATE_VIS remove_reference<_Tp&&> {typedef _LIBCPP_NODEBUG_TYPE _Tp type;};
1112
1113#if _LIBCPP_STD_VER > 11
1114template <class _Tp> using remove_reference_t = typename remove_reference<_Tp>::type;
1115#endif
1116
1117// add_lvalue_reference
1118
1119template <class _Tp, bool = __is_referenceable<_Tp>::value> struct __add_lvalue_reference_impl            { typedef _LIBCPP_NODEBUG_TYPE _Tp  type; };
1120template <class _Tp                                       > struct __add_lvalue_reference_impl<_Tp, true> { typedef _LIBCPP_NODEBUG_TYPE _Tp& type; };
1121
1122template <class _Tp> struct _LIBCPP_TEMPLATE_VIS add_lvalue_reference
1123{typedef _LIBCPP_NODEBUG_TYPE typename  __add_lvalue_reference_impl<_Tp>::type type;};
1124
1125#if _LIBCPP_STD_VER > 11
1126template <class _Tp> using add_lvalue_reference_t = typename add_lvalue_reference<_Tp>::type;
1127#endif
1128
1129template <class _Tp, bool = __is_referenceable<_Tp>::value> struct __add_rvalue_reference_impl            { typedef _LIBCPP_NODEBUG_TYPE  _Tp   type; };
1130template <class _Tp                                       > struct __add_rvalue_reference_impl<_Tp, true> { typedef _LIBCPP_NODEBUG_TYPE  _Tp&& type; };
1131
1132template <class _Tp> struct _LIBCPP_TEMPLATE_VIS add_rvalue_reference
1133{typedef _LIBCPP_NODEBUG_TYPE  typename __add_rvalue_reference_impl<_Tp>::type type;};
1134
1135#if _LIBCPP_STD_VER > 11
1136template <class _Tp> using add_rvalue_reference_t = typename add_rvalue_reference<_Tp>::type;
1137#endif
1138
1139// Suppress deprecation notice for volatile-qualified return type resulting
1140// from volatile-qualified types _Tp.
1141_LIBCPP_SUPPRESS_DEPRECATED_PUSH
1142template <class _Tp> _Tp&& __declval(int);
1143template <class _Tp> _Tp   __declval(long);
1144_LIBCPP_SUPPRESS_DEPRECATED_POP
1145
1146template <class _Tp>
1147decltype(_VSTD::__declval<_Tp>(0))
1148declval() _NOEXCEPT;
1149
1150// __uncvref
1151
1152template <class _Tp>
1153struct __uncvref  {
1154    typedef _LIBCPP_NODEBUG_TYPE typename remove_cv<typename remove_reference<_Tp>::type>::type type;
1155};
1156
1157template <class _Tp>
1158struct __unconstref {
1159    typedef _LIBCPP_NODEBUG_TYPE typename remove_const<typename remove_reference<_Tp>::type>::type type;
1160};
1161
1162#ifndef _LIBCPP_CXX03_LANG
1163template <class _Tp>
1164using __uncvref_t _LIBCPP_NODEBUG_TYPE = typename __uncvref<_Tp>::type;
1165#endif
1166
1167// __is_same_uncvref
1168
1169template <class _Tp, class _Up>
1170struct __is_same_uncvref : _IsSame<typename __uncvref<_Tp>::type,
1171                                   typename __uncvref<_Up>::type> {};
1172
1173#if _LIBCPP_STD_VER > 17
1174// remove_cvref - same as __uncvref
1175template <class _Tp>
1176struct remove_cvref : public __uncvref<_Tp> {};
1177
1178template <class _Tp> using remove_cvref_t = typename remove_cvref<_Tp>::type;
1179#endif
1180
1181
1182struct __any
1183{
1184    __any(...);
1185};
1186
1187// remove_pointer
1188
1189template <class _Tp> struct _LIBCPP_TEMPLATE_VIS remove_pointer                      {typedef _LIBCPP_NODEBUG_TYPE _Tp type;};
1190template <class _Tp> struct _LIBCPP_TEMPLATE_VIS remove_pointer<_Tp*>                {typedef _LIBCPP_NODEBUG_TYPE _Tp type;};
1191template <class _Tp> struct _LIBCPP_TEMPLATE_VIS remove_pointer<_Tp* const>          {typedef _LIBCPP_NODEBUG_TYPE _Tp type;};
1192template <class _Tp> struct _LIBCPP_TEMPLATE_VIS remove_pointer<_Tp* volatile>       {typedef _LIBCPP_NODEBUG_TYPE _Tp type;};
1193template <class _Tp> struct _LIBCPP_TEMPLATE_VIS remove_pointer<_Tp* const volatile> {typedef _LIBCPP_NODEBUG_TYPE _Tp type;};
1194
1195#if _LIBCPP_STD_VER > 11
1196template <class _Tp> using remove_pointer_t = typename remove_pointer<_Tp>::type;
1197#endif
1198
1199// add_pointer
1200
1201template <class _Tp,
1202        bool = __is_referenceable<_Tp>::value ||
1203                _IsSame<typename remove_cv<_Tp>::type, void>::value>
1204struct __add_pointer_impl
1205    {typedef _LIBCPP_NODEBUG_TYPE typename remove_reference<_Tp>::type* type;};
1206template <class _Tp> struct __add_pointer_impl<_Tp, false>
1207    {typedef _LIBCPP_NODEBUG_TYPE _Tp type;};
1208
1209template <class _Tp> struct _LIBCPP_TEMPLATE_VIS add_pointer
1210    {typedef _LIBCPP_NODEBUG_TYPE typename __add_pointer_impl<_Tp>::type type;};
1211
1212#if _LIBCPP_STD_VER > 11
1213template <class _Tp> using add_pointer_t = typename add_pointer<_Tp>::type;
1214#endif
1215
1216// type_identity
1217#if _LIBCPP_STD_VER > 17
1218template<class _Tp> struct type_identity { typedef _Tp type; };
1219template<class _Tp> using type_identity_t = typename type_identity<_Tp>::type;
1220#endif
1221
1222// is_signed
1223
1224template <class _Tp, bool = is_integral<_Tp>::value>
1225struct __libcpp_is_signed_impl : public _LIBCPP_BOOL_CONSTANT(_Tp(-1) < _Tp(0)) {};
1226
1227template <class _Tp>
1228struct __libcpp_is_signed_impl<_Tp, false> : public true_type {};  // floating point
1229
1230template <class _Tp, bool = is_arithmetic<_Tp>::value>
1231struct __libcpp_is_signed : public __libcpp_is_signed_impl<_Tp> {};
1232
1233template <class _Tp> struct __libcpp_is_signed<_Tp, false> : public false_type {};
1234
1235template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_signed : public __libcpp_is_signed<_Tp> {};
1236
1237#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
1238template <class _Tp>
1239_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_signed_v
1240    = is_signed<_Tp>::value;
1241#endif
1242
1243// is_unsigned
1244
1245template <class _Tp, bool = is_integral<_Tp>::value>
1246struct __libcpp_is_unsigned_impl : public _LIBCPP_BOOL_CONSTANT(_Tp(0) < _Tp(-1)) {};
1247
1248template <class _Tp>
1249struct __libcpp_is_unsigned_impl<_Tp, false> : public false_type {};  // floating point
1250
1251template <class _Tp, bool = is_arithmetic<_Tp>::value>
1252struct __libcpp_is_unsigned : public __libcpp_is_unsigned_impl<_Tp> {};
1253
1254template <class _Tp> struct __libcpp_is_unsigned<_Tp, false> : public false_type {};
1255
1256template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_unsigned : public __libcpp_is_unsigned<_Tp> {};
1257
1258#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
1259template <class _Tp>
1260_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_unsigned_v
1261    = is_unsigned<_Tp>::value;
1262#endif
1263
1264// rank
1265
1266template <class _Tp> struct _LIBCPP_TEMPLATE_VIS rank
1267    : public integral_constant<size_t, 0> {};
1268template <class _Tp> struct _LIBCPP_TEMPLATE_VIS rank<_Tp[]>
1269    : public integral_constant<size_t, rank<_Tp>::value + 1> {};
1270template <class _Tp, size_t _Np> struct _LIBCPP_TEMPLATE_VIS rank<_Tp[_Np]>
1271    : public integral_constant<size_t, rank<_Tp>::value + 1> {};
1272
1273#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
1274template <class _Tp>
1275_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR size_t rank_v
1276    = rank<_Tp>::value;
1277#endif
1278
1279// extent
1280
1281template <class _Tp, unsigned _Ip = 0> struct _LIBCPP_TEMPLATE_VIS extent
1282    : public integral_constant<size_t, 0> {};
1283template <class _Tp> struct _LIBCPP_TEMPLATE_VIS extent<_Tp[], 0>
1284    : public integral_constant<size_t, 0> {};
1285template <class _Tp, unsigned _Ip> struct _LIBCPP_TEMPLATE_VIS extent<_Tp[], _Ip>
1286    : public integral_constant<size_t, extent<_Tp, _Ip-1>::value> {};
1287template <class _Tp, size_t _Np> struct _LIBCPP_TEMPLATE_VIS extent<_Tp[_Np], 0>
1288    : public integral_constant<size_t, _Np> {};
1289template <class _Tp, size_t _Np, unsigned _Ip> struct _LIBCPP_TEMPLATE_VIS extent<_Tp[_Np], _Ip>
1290    : public integral_constant<size_t, extent<_Tp, _Ip-1>::value> {};
1291
1292#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
1293template <class _Tp, unsigned _Ip = 0>
1294_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR size_t extent_v
1295    = extent<_Tp, _Ip>::value;
1296#endif
1297
1298// remove_extent
1299
1300template <class _Tp> struct _LIBCPP_TEMPLATE_VIS remove_extent
1301    {typedef _Tp type;};
1302template <class _Tp> struct _LIBCPP_TEMPLATE_VIS remove_extent<_Tp[]>
1303    {typedef _Tp type;};
1304template <class _Tp, size_t _Np> struct _LIBCPP_TEMPLATE_VIS remove_extent<_Tp[_Np]>
1305    {typedef _Tp type;};
1306
1307#if _LIBCPP_STD_VER > 11
1308template <class _Tp> using remove_extent_t = typename remove_extent<_Tp>::type;
1309#endif
1310
1311// remove_all_extents
1312
1313template <class _Tp> struct _LIBCPP_TEMPLATE_VIS remove_all_extents
1314    {typedef _Tp type;};
1315template <class _Tp> struct _LIBCPP_TEMPLATE_VIS remove_all_extents<_Tp[]>
1316    {typedef typename remove_all_extents<_Tp>::type type;};
1317template <class _Tp, size_t _Np> struct _LIBCPP_TEMPLATE_VIS remove_all_extents<_Tp[_Np]>
1318    {typedef typename remove_all_extents<_Tp>::type type;};
1319
1320#if _LIBCPP_STD_VER > 11
1321template <class _Tp> using remove_all_extents_t = typename remove_all_extents<_Tp>::type;
1322#endif
1323
1324#if _LIBCPP_STD_VER > 17
1325// is_bounded_array
1326
1327template <class>                 struct _LIBCPP_TEMPLATE_VIS is_bounded_array           : false_type {};
1328template <class _Tp, size_t _Np> struct _LIBCPP_TEMPLATE_VIS is_bounded_array<_Tp[_Np]> : true_type {};
1329
1330template <class _Tp>
1331_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR
1332bool is_bounded_array_v  = is_bounded_array<_Tp>::value;
1333
1334// is_unbounded_array
1335
1336template <class>     struct _LIBCPP_TEMPLATE_VIS is_unbounded_array        : false_type {};
1337template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_unbounded_array<_Tp[]> : true_type {};
1338
1339template <class _Tp>
1340_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR
1341bool is_unbounded_array_v  = is_unbounded_array<_Tp>::value;
1342#endif
1343
1344// decay
1345
1346template <class _Up, bool>
1347struct __decay {
1348    typedef _LIBCPP_NODEBUG_TYPE typename remove_cv<_Up>::type type;
1349};
1350
1351template <class _Up>
1352struct __decay<_Up, true> {
1353public:
1354    typedef _LIBCPP_NODEBUG_TYPE typename conditional
1355                     <
1356                         is_array<_Up>::value,
1357                         typename remove_extent<_Up>::type*,
1358                         typename conditional
1359                         <
1360                              is_function<_Up>::value,
1361                              typename add_pointer<_Up>::type,
1362                              typename remove_cv<_Up>::type
1363                         >::type
1364                     >::type type;
1365};
1366
1367template <class _Tp>
1368struct _LIBCPP_TEMPLATE_VIS decay
1369{
1370private:
1371    typedef _LIBCPP_NODEBUG_TYPE typename remove_reference<_Tp>::type _Up;
1372public:
1373    typedef _LIBCPP_NODEBUG_TYPE typename __decay<_Up, __is_referenceable<_Up>::value>::type type;
1374};
1375
1376#if _LIBCPP_STD_VER > 11
1377template <class _Tp> using decay_t = typename decay<_Tp>::type;
1378#endif
1379
1380// is_abstract
1381
1382template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_abstract
1383    : public integral_constant<bool, __is_abstract(_Tp)> {};
1384
1385#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
1386template <class _Tp>
1387_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_abstract_v
1388    = is_abstract<_Tp>::value;
1389#endif
1390
1391// is_final
1392
1393template <class _Tp> struct _LIBCPP_TEMPLATE_VIS
1394__libcpp_is_final : public integral_constant<bool, __is_final(_Tp)> {};
1395
1396#if _LIBCPP_STD_VER > 11
1397template <class _Tp> struct _LIBCPP_TEMPLATE_VIS
1398is_final : public integral_constant<bool, __is_final(_Tp)> {};
1399#endif
1400
1401#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
1402template <class _Tp>
1403_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_final_v
1404    = is_final<_Tp>::value;
1405#endif
1406
1407// is_aggregate
1408#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_IS_AGGREGATE)
1409
1410template <class _Tp> struct _LIBCPP_TEMPLATE_VIS
1411is_aggregate : public integral_constant<bool, __is_aggregate(_Tp)> {};
1412
1413#if !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
1414template <class _Tp>
1415_LIBCPP_INLINE_VAR constexpr bool is_aggregate_v
1416    = is_aggregate<_Tp>::value;
1417#endif
1418
1419#endif // _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_IS_AGGREGATE)
1420
1421// is_base_of
1422
1423template <class _Bp, class _Dp>
1424struct _LIBCPP_TEMPLATE_VIS is_base_of
1425    : public integral_constant<bool, __is_base_of(_Bp, _Dp)> {};
1426
1427#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
1428template <class _Bp, class _Dp>
1429_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_base_of_v
1430    = is_base_of<_Bp, _Dp>::value;
1431#endif
1432
1433// is_convertible
1434
1435#if __has_feature(is_convertible_to) && !defined(_LIBCPP_USE_IS_CONVERTIBLE_FALLBACK)
1436
1437template <class _T1, class _T2> struct _LIBCPP_TEMPLATE_VIS is_convertible
1438    : public integral_constant<bool, __is_convertible_to(_T1, _T2)> {};
1439
1440#else  // __has_feature(is_convertible_to)
1441
1442namespace __is_convertible_imp
1443{
1444template <class _Tp> void  __test_convert(_Tp);
1445
1446template <class _From, class _To, class = void>
1447struct __is_convertible_test : public false_type {};
1448
1449template <class _From, class _To>
1450struct __is_convertible_test<_From, _To,
1451    decltype(_VSTD::__is_convertible_imp::__test_convert<_To>(_VSTD::declval<_From>()))> : public true_type
1452{};
1453
1454template <class _Tp, bool _IsArray =    is_array<_Tp>::value,
1455                     bool _IsFunction = is_function<_Tp>::value,
1456                     bool _IsVoid =     is_void<_Tp>::value>
1457                     struct __is_array_function_or_void                          {enum {value = 0};};
1458template <class _Tp> struct __is_array_function_or_void<_Tp, true, false, false> {enum {value = 1};};
1459template <class _Tp> struct __is_array_function_or_void<_Tp, false, true, false> {enum {value = 2};};
1460template <class _Tp> struct __is_array_function_or_void<_Tp, false, false, true> {enum {value = 3};};
1461}
1462
1463template <class _Tp,
1464    unsigned = __is_convertible_imp::__is_array_function_or_void<typename remove_reference<_Tp>::type>::value>
1465struct __is_convertible_check
1466{
1467    static const size_t __v = 0;
1468};
1469
1470template <class _Tp>
1471struct __is_convertible_check<_Tp, 0>
1472{
1473    static const size_t __v = sizeof(_Tp);
1474};
1475
1476template <class _T1, class _T2,
1477    unsigned _T1_is_array_function_or_void = __is_convertible_imp::__is_array_function_or_void<_T1>::value,
1478    unsigned _T2_is_array_function_or_void = __is_convertible_imp::__is_array_function_or_void<_T2>::value>
1479struct __is_convertible
1480    : public integral_constant<bool,
1481        __is_convertible_imp::__is_convertible_test<_T1, _T2>::value
1482    >
1483{};
1484
1485template <class _T1, class _T2> struct __is_convertible<_T1, _T2, 0, 1> : public false_type {};
1486template <class _T1, class _T2> struct __is_convertible<_T1, _T2, 1, 1> : public false_type {};
1487template <class _T1, class _T2> struct __is_convertible<_T1, _T2, 2, 1> : public false_type {};
1488template <class _T1, class _T2> struct __is_convertible<_T1, _T2, 3, 1> : public false_type {};
1489
1490template <class _T1, class _T2> struct __is_convertible<_T1, _T2, 0, 2> : public false_type {};
1491template <class _T1, class _T2> struct __is_convertible<_T1, _T2, 1, 2> : public false_type {};
1492template <class _T1, class _T2> struct __is_convertible<_T1, _T2, 2, 2> : public false_type {};
1493template <class _T1, class _T2> struct __is_convertible<_T1, _T2, 3, 2> : public false_type {};
1494
1495template <class _T1, class _T2> struct __is_convertible<_T1, _T2, 0, 3> : public false_type {};
1496template <class _T1, class _T2> struct __is_convertible<_T1, _T2, 1, 3> : public false_type {};
1497template <class _T1, class _T2> struct __is_convertible<_T1, _T2, 2, 3> : public false_type {};
1498template <class _T1, class _T2> struct __is_convertible<_T1, _T2, 3, 3> : public true_type {};
1499
1500template <class _T1, class _T2> struct _LIBCPP_TEMPLATE_VIS is_convertible
1501    : public __is_convertible<_T1, _T2>
1502{
1503    static const size_t __complete_check1 = __is_convertible_check<_T1>::__v;
1504    static const size_t __complete_check2 = __is_convertible_check<_T2>::__v;
1505};
1506
1507#endif  // __has_feature(is_convertible_to)
1508
1509#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
1510template <class _From, class _To>
1511_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_convertible_v
1512    = is_convertible<_From, _To>::value;
1513#endif
1514
1515// is_nothrow_convertible
1516
1517#if _LIBCPP_STD_VER > 17
1518
1519template <typename _Tp>
1520static void __test_noexcept(_Tp) noexcept;
1521
1522template<typename _Fm, typename _To>
1523static bool_constant<noexcept(__test_noexcept<_To>(declval<_Fm>()))>
1524__is_nothrow_convertible_test();
1525
1526template <typename _Fm, typename _To>
1527struct __is_nothrow_convertible_helper: decltype(__is_nothrow_convertible_test<_Fm, _To>())
1528{ };
1529
1530template <typename _Fm, typename _To>
1531struct is_nothrow_convertible : _Or<
1532    _And<is_void<_To>, is_void<_Fm>>,
1533    _Lazy<_And, is_convertible<_Fm, _To>, __is_nothrow_convertible_helper<_Fm, _To>>
1534>::type { };
1535
1536template <typename _Fm, typename _To>
1537inline constexpr bool is_nothrow_convertible_v = is_nothrow_convertible<_Fm, _To>::value;
1538
1539#endif // _LIBCPP_STD_VER > 17
1540
1541// is_empty
1542
1543#if __has_feature(is_empty) || defined(_LIBCPP_COMPILER_GCC)
1544
1545template <class _Tp>
1546struct _LIBCPP_TEMPLATE_VIS is_empty
1547    : public integral_constant<bool, __is_empty(_Tp)> {};
1548
1549#else  // __has_feature(is_empty)
1550
1551template <class _Tp>
1552struct __is_empty1
1553    : public _Tp
1554{
1555    double __lx;
1556};
1557
1558struct __is_empty2
1559{
1560    double __lx;
1561};
1562
1563template <class _Tp, bool = is_class<_Tp>::value>
1564struct __libcpp_empty : public integral_constant<bool, sizeof(__is_empty1<_Tp>) == sizeof(__is_empty2)> {};
1565
1566template <class _Tp> struct __libcpp_empty<_Tp, false> : public false_type {};
1567
1568template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_empty : public __libcpp_empty<_Tp> {};
1569
1570#endif  // __has_feature(is_empty)
1571
1572#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
1573template <class _Tp>
1574_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_empty_v
1575    = is_empty<_Tp>::value;
1576#endif
1577
1578// is_polymorphic
1579
1580#if __has_feature(is_polymorphic) || defined(_LIBCPP_COMPILER_MSVC)
1581
1582template <class _Tp>
1583struct _LIBCPP_TEMPLATE_VIS is_polymorphic
1584    : public integral_constant<bool, __is_polymorphic(_Tp)> {};
1585
1586#else
1587
1588template<typename _Tp> char &__is_polymorphic_impl(
1589    typename enable_if<sizeof((_Tp*)dynamic_cast<const volatile void*>(declval<_Tp*>())) != 0,
1590                       int>::type);
1591template<typename _Tp> __two &__is_polymorphic_impl(...);
1592
1593template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_polymorphic
1594    : public integral_constant<bool, sizeof(__is_polymorphic_impl<_Tp>(0)) == 1> {};
1595
1596#endif // __has_feature(is_polymorphic)
1597
1598#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
1599template <class _Tp>
1600_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_polymorphic_v
1601    = is_polymorphic<_Tp>::value;
1602#endif
1603
1604// has_virtual_destructor
1605
1606#if __has_feature(has_virtual_destructor) || defined(_LIBCPP_COMPILER_GCC)
1607
1608template <class _Tp> struct _LIBCPP_TEMPLATE_VIS has_virtual_destructor
1609    : public integral_constant<bool, __has_virtual_destructor(_Tp)> {};
1610
1611#else
1612
1613template <class _Tp> struct _LIBCPP_TEMPLATE_VIS has_virtual_destructor
1614    : public false_type {};
1615
1616#endif
1617
1618#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
1619template <class _Tp>
1620_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool has_virtual_destructor_v
1621    = has_virtual_destructor<_Tp>::value;
1622#endif
1623
1624// has_unique_object_representations
1625
1626#if _LIBCPP_STD_VER > 14 && defined(_LIBCPP_HAS_UNIQUE_OBJECT_REPRESENTATIONS)
1627
1628template <class _Tp> struct _LIBCPP_TEMPLATE_VIS has_unique_object_representations
1629    : public integral_constant<bool,
1630       __has_unique_object_representations(remove_cv_t<remove_all_extents_t<_Tp>>)> {};
1631
1632#if !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
1633template <class _Tp>
1634_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool has_unique_object_representations_v
1635    = has_unique_object_representations<_Tp>::value;
1636#endif
1637
1638#endif
1639
1640// alignment_of
1641
1642template <class _Tp> struct _LIBCPP_TEMPLATE_VIS alignment_of
1643    : public integral_constant<size_t, _LIBCPP_ALIGNOF(_Tp)> {};
1644
1645#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
1646template <class _Tp>
1647_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR size_t alignment_of_v
1648    = alignment_of<_Tp>::value;
1649#endif
1650
1651// aligned_storage
1652
1653template <class _Hp, class _Tp>
1654struct __type_list
1655{
1656    typedef _Hp _Head;
1657    typedef _Tp _Tail;
1658};
1659
1660struct __nat
1661{
1662#ifndef _LIBCPP_CXX03_LANG
1663    __nat() = delete;
1664    __nat(const __nat&) = delete;
1665    __nat& operator=(const __nat&) = delete;
1666    ~__nat() = delete;
1667#endif
1668};
1669
1670template <class _Tp>
1671struct __align_type
1672{
1673    static const size_t value = _LIBCPP_PREFERRED_ALIGNOF(_Tp);
1674    typedef _Tp type;
1675};
1676
1677struct __struct_double {long double __lx;};
1678struct __struct_double4 {double __lx[4];};
1679
1680typedef
1681    __type_list<__align_type<unsigned char>,
1682    __type_list<__align_type<unsigned short>,
1683    __type_list<__align_type<unsigned int>,
1684    __type_list<__align_type<unsigned long>,
1685    __type_list<__align_type<unsigned long long>,
1686    __type_list<__align_type<double>,
1687    __type_list<__align_type<long double>,
1688    __type_list<__align_type<__struct_double>,
1689    __type_list<__align_type<__struct_double4>,
1690    __type_list<__align_type<int*>,
1691    __nat
1692    > > > > > > > > > > __all_types;
1693
1694template <size_t _Align>
1695struct _ALIGNAS(_Align) __fallback_overaligned {};
1696
1697template <class _TL, size_t _Align> struct __find_pod;
1698
1699template <class _Hp, size_t _Align>
1700struct __find_pod<__type_list<_Hp, __nat>, _Align>
1701{
1702    typedef typename conditional<
1703                             _Align == _Hp::value,
1704                             typename _Hp::type,
1705                             __fallback_overaligned<_Align>
1706                         >::type type;
1707};
1708
1709template <class _Hp, class _Tp, size_t _Align>
1710struct __find_pod<__type_list<_Hp, _Tp>, _Align>
1711{
1712    typedef typename conditional<
1713                             _Align == _Hp::value,
1714                             typename _Hp::type,
1715                             typename __find_pod<_Tp, _Align>::type
1716                         >::type type;
1717};
1718
1719template <class _TL, size_t _Len> struct __find_max_align;
1720
1721template <class _Hp, size_t _Len>
1722struct __find_max_align<__type_list<_Hp, __nat>, _Len> : public integral_constant<size_t, _Hp::value> {};
1723
1724template <size_t _Len, size_t _A1, size_t _A2>
1725struct __select_align
1726{
1727private:
1728    static const size_t __min = _A2 < _A1 ? _A2 : _A1;
1729    static const size_t __max = _A1 < _A2 ? _A2 : _A1;
1730public:
1731    static const size_t value = _Len < __max ? __min : __max;
1732};
1733
1734template <class _Hp, class _Tp, size_t _Len>
1735struct __find_max_align<__type_list<_Hp, _Tp>, _Len>
1736    : public integral_constant<size_t, __select_align<_Len, _Hp::value, __find_max_align<_Tp, _Len>::value>::value> {};
1737
1738template <size_t _Len, size_t _Align = __find_max_align<__all_types, _Len>::value>
1739struct _LIBCPP_TEMPLATE_VIS aligned_storage
1740{
1741    typedef typename __find_pod<__all_types, _Align>::type _Aligner;
1742    union type
1743    {
1744        _Aligner __align;
1745        unsigned char __data[(_Len + _Align - 1)/_Align * _Align];
1746    };
1747};
1748
1749#if _LIBCPP_STD_VER > 11
1750template <size_t _Len, size_t _Align = __find_max_align<__all_types, _Len>::value>
1751    using aligned_storage_t = typename aligned_storage<_Len, _Align>::type;
1752#endif
1753
1754#define _CREATE_ALIGNED_STORAGE_SPECIALIZATION(n) \
1755template <size_t _Len>\
1756struct _LIBCPP_TEMPLATE_VIS aligned_storage<_Len, n>\
1757{\
1758    struct _ALIGNAS(n) type\
1759    {\
1760        unsigned char __lx[(_Len + n - 1)/n * n];\
1761    };\
1762}
1763
1764_CREATE_ALIGNED_STORAGE_SPECIALIZATION(0x1);
1765_CREATE_ALIGNED_STORAGE_SPECIALIZATION(0x2);
1766_CREATE_ALIGNED_STORAGE_SPECIALIZATION(0x4);
1767_CREATE_ALIGNED_STORAGE_SPECIALIZATION(0x8);
1768_CREATE_ALIGNED_STORAGE_SPECIALIZATION(0x10);
1769_CREATE_ALIGNED_STORAGE_SPECIALIZATION(0x20);
1770_CREATE_ALIGNED_STORAGE_SPECIALIZATION(0x40);
1771_CREATE_ALIGNED_STORAGE_SPECIALIZATION(0x80);
1772_CREATE_ALIGNED_STORAGE_SPECIALIZATION(0x100);
1773_CREATE_ALIGNED_STORAGE_SPECIALIZATION(0x200);
1774_CREATE_ALIGNED_STORAGE_SPECIALIZATION(0x400);
1775_CREATE_ALIGNED_STORAGE_SPECIALIZATION(0x800);
1776_CREATE_ALIGNED_STORAGE_SPECIALIZATION(0x1000);
1777_CREATE_ALIGNED_STORAGE_SPECIALIZATION(0x2000);
1778// PE/COFF does not support alignment beyond 8192 (=0x2000)
1779#if !defined(_LIBCPP_OBJECT_FORMAT_COFF)
1780_CREATE_ALIGNED_STORAGE_SPECIALIZATION(0x4000);
1781#endif // !defined(_LIBCPP_OBJECT_FORMAT_COFF)
1782
1783#undef _CREATE_ALIGNED_STORAGE_SPECIALIZATION
1784
1785
1786// aligned_union
1787
1788template <size_t _I0, size_t ..._In>
1789struct __static_max;
1790
1791template <size_t _I0>
1792struct __static_max<_I0>
1793{
1794    static const size_t value = _I0;
1795};
1796
1797template <size_t _I0, size_t _I1, size_t ..._In>
1798struct __static_max<_I0, _I1, _In...>
1799{
1800    static const size_t value = _I0 >= _I1 ? __static_max<_I0, _In...>::value :
1801                                             __static_max<_I1, _In...>::value;
1802};
1803
1804template <size_t _Len, class _Type0, class ..._Types>
1805struct aligned_union
1806{
1807    static const size_t alignment_value = __static_max<_LIBCPP_PREFERRED_ALIGNOF(_Type0),
1808                                                       _LIBCPP_PREFERRED_ALIGNOF(_Types)...>::value;
1809    static const size_t __len = __static_max<_Len, sizeof(_Type0),
1810                                             sizeof(_Types)...>::value;
1811    typedef typename aligned_storage<__len, alignment_value>::type type;
1812};
1813
1814#if _LIBCPP_STD_VER > 11
1815template <size_t _Len, class ..._Types> using aligned_union_t = typename aligned_union<_Len, _Types...>::type;
1816#endif
1817
1818template <class _Tp>
1819struct __numeric_type
1820{
1821   static void __test(...);
1822   static float __test(float);
1823   static double __test(char);
1824   static double __test(int);
1825   static double __test(unsigned);
1826   static double __test(long);
1827   static double __test(unsigned long);
1828   static double __test(long long);
1829   static double __test(unsigned long long);
1830   static double __test(double);
1831   static long double __test(long double);
1832
1833   typedef decltype(__test(declval<_Tp>())) type;
1834   static const bool value = _IsNotSame<type, void>::value;
1835};
1836
1837template <>
1838struct __numeric_type<void>
1839{
1840   static const bool value = true;
1841};
1842
1843// __promote
1844
1845template <class _A1, class _A2 = void, class _A3 = void,
1846          bool = __numeric_type<_A1>::value &&
1847                 __numeric_type<_A2>::value &&
1848                 __numeric_type<_A3>::value>
1849class __promote_imp
1850{
1851public:
1852    static const bool value = false;
1853};
1854
1855template <class _A1, class _A2, class _A3>
1856class __promote_imp<_A1, _A2, _A3, true>
1857{
1858private:
1859    typedef typename __promote_imp<_A1>::type __type1;
1860    typedef typename __promote_imp<_A2>::type __type2;
1861    typedef typename __promote_imp<_A3>::type __type3;
1862public:
1863    typedef decltype(__type1() + __type2() + __type3()) type;
1864    static const bool value = true;
1865};
1866
1867template <class _A1, class _A2>
1868class __promote_imp<_A1, _A2, void, true>
1869{
1870private:
1871    typedef typename __promote_imp<_A1>::type __type1;
1872    typedef typename __promote_imp<_A2>::type __type2;
1873public:
1874    typedef decltype(__type1() + __type2()) type;
1875    static const bool value = true;
1876};
1877
1878template <class _A1>
1879class __promote_imp<_A1, void, void, true>
1880{
1881public:
1882    typedef typename __numeric_type<_A1>::type type;
1883    static const bool value = true;
1884};
1885
1886template <class _A1, class _A2 = void, class _A3 = void>
1887class __promote : public __promote_imp<_A1, _A2, _A3> {};
1888
1889// make_signed / make_unsigned
1890
1891typedef
1892    __type_list<signed char,
1893    __type_list<signed short,
1894    __type_list<signed int,
1895    __type_list<signed long,
1896    __type_list<signed long long,
1897#ifndef _LIBCPP_HAS_NO_INT128
1898    __type_list<__int128_t,
1899#endif
1900    __nat
1901#ifndef _LIBCPP_HAS_NO_INT128
1902    >
1903#endif
1904    > > > > > __signed_types;
1905
1906typedef
1907    __type_list<unsigned char,
1908    __type_list<unsigned short,
1909    __type_list<unsigned int,
1910    __type_list<unsigned long,
1911    __type_list<unsigned long long,
1912#ifndef _LIBCPP_HAS_NO_INT128
1913    __type_list<__uint128_t,
1914#endif
1915    __nat
1916#ifndef _LIBCPP_HAS_NO_INT128
1917    >
1918#endif
1919    > > > > > __unsigned_types;
1920
1921template <class _TypeList, size_t _Size, bool = _Size <= sizeof(typename _TypeList::_Head)> struct __find_first;
1922
1923template <class _Hp, class _Tp, size_t _Size>
1924struct __find_first<__type_list<_Hp, _Tp>, _Size, true>
1925{
1926    typedef _LIBCPP_NODEBUG_TYPE _Hp type;
1927};
1928
1929template <class _Hp, class _Tp, size_t _Size>
1930struct __find_first<__type_list<_Hp, _Tp>, _Size, false>
1931{
1932    typedef _LIBCPP_NODEBUG_TYPE typename __find_first<_Tp, _Size>::type type;
1933};
1934
1935template <class _Tp, class _Up, bool = is_const<typename remove_reference<_Tp>::type>::value,
1936                             bool = is_volatile<typename remove_reference<_Tp>::type>::value>
1937struct __apply_cv
1938{
1939    typedef _LIBCPP_NODEBUG_TYPE _Up type;
1940};
1941
1942template <class _Tp, class _Up>
1943struct __apply_cv<_Tp, _Up, true, false>
1944{
1945    typedef _LIBCPP_NODEBUG_TYPE const _Up type;
1946};
1947
1948template <class _Tp, class _Up>
1949struct __apply_cv<_Tp, _Up, false, true>
1950{
1951    typedef volatile _Up type;
1952};
1953
1954template <class _Tp, class _Up>
1955struct __apply_cv<_Tp, _Up, true, true>
1956{
1957    typedef const volatile _Up type;
1958};
1959
1960template <class _Tp, class _Up>
1961struct __apply_cv<_Tp&, _Up, false, false>
1962{
1963    typedef _Up& type;
1964};
1965
1966template <class _Tp, class _Up>
1967struct __apply_cv<_Tp&, _Up, true, false>
1968{
1969    typedef const _Up& type;
1970};
1971
1972template <class _Tp, class _Up>
1973struct __apply_cv<_Tp&, _Up, false, true>
1974{
1975    typedef volatile _Up& type;
1976};
1977
1978template <class _Tp, class _Up>
1979struct __apply_cv<_Tp&, _Up, true, true>
1980{
1981    typedef const volatile _Up& type;
1982};
1983
1984template <class _Tp, bool = is_integral<_Tp>::value || is_enum<_Tp>::value>
1985struct __make_signed {};
1986
1987template <class _Tp>
1988struct __make_signed<_Tp, true>
1989{
1990    typedef typename __find_first<__signed_types, sizeof(_Tp)>::type type;
1991};
1992
1993template <> struct __make_signed<bool,               true> {};
1994template <> struct __make_signed<  signed short,     true> {typedef short     type;};
1995template <> struct __make_signed<unsigned short,     true> {typedef short     type;};
1996template <> struct __make_signed<  signed int,       true> {typedef int       type;};
1997template <> struct __make_signed<unsigned int,       true> {typedef int       type;};
1998template <> struct __make_signed<  signed long,      true> {typedef long      type;};
1999template <> struct __make_signed<unsigned long,      true> {typedef long      type;};
2000template <> struct __make_signed<  signed long long, true> {typedef long long type;};
2001template <> struct __make_signed<unsigned long long, true> {typedef long long type;};
2002#ifndef _LIBCPP_HAS_NO_INT128
2003template <> struct __make_signed<__int128_t,         true> {typedef __int128_t type;};
2004template <> struct __make_signed<__uint128_t,        true> {typedef __int128_t type;};
2005#endif
2006
2007template <class _Tp>
2008struct _LIBCPP_TEMPLATE_VIS make_signed
2009{
2010    typedef typename __apply_cv<_Tp, typename __make_signed<typename remove_cv<_Tp>::type>::type>::type type;
2011};
2012
2013#if _LIBCPP_STD_VER > 11
2014template <class _Tp> using make_signed_t = typename make_signed<_Tp>::type;
2015#endif
2016
2017template <class _Tp, bool = is_integral<_Tp>::value || is_enum<_Tp>::value>
2018struct __make_unsigned {};
2019
2020template <class _Tp>
2021struct __make_unsigned<_Tp, true>
2022{
2023    typedef typename __find_first<__unsigned_types, sizeof(_Tp)>::type type;
2024};
2025
2026template <> struct __make_unsigned<bool,               true> {};
2027template <> struct __make_unsigned<  signed short,     true> {typedef unsigned short     type;};
2028template <> struct __make_unsigned<unsigned short,     true> {typedef unsigned short     type;};
2029template <> struct __make_unsigned<  signed int,       true> {typedef unsigned int       type;};
2030template <> struct __make_unsigned<unsigned int,       true> {typedef unsigned int       type;};
2031template <> struct __make_unsigned<  signed long,      true> {typedef unsigned long      type;};
2032template <> struct __make_unsigned<unsigned long,      true> {typedef unsigned long      type;};
2033template <> struct __make_unsigned<  signed long long, true> {typedef unsigned long long type;};
2034template <> struct __make_unsigned<unsigned long long, true> {typedef unsigned long long type;};
2035#ifndef _LIBCPP_HAS_NO_INT128
2036template <> struct __make_unsigned<__int128_t,         true> {typedef __uint128_t        type;};
2037template <> struct __make_unsigned<__uint128_t,        true> {typedef __uint128_t        type;};
2038#endif
2039
2040template <class _Tp>
2041struct _LIBCPP_TEMPLATE_VIS make_unsigned
2042{
2043    typedef typename __apply_cv<_Tp, typename __make_unsigned<typename remove_cv<_Tp>::type>::type>::type type;
2044};
2045
2046#if _LIBCPP_STD_VER > 11
2047template <class _Tp> using make_unsigned_t = typename make_unsigned<_Tp>::type;
2048#endif
2049
2050template <class _Tp, class _Up, class = void>
2051struct __common_type2_imp {};
2052
2053template <class _Tp, class _Up>
2054struct __common_type2_imp<_Tp, _Up,
2055                          typename __void_t<decltype(
2056                                            true ? _VSTD::declval<_Tp>() : _VSTD::declval<_Up>()
2057                                            )>::type>
2058{
2059  typedef _LIBCPP_NODEBUG_TYPE typename decay<decltype(
2060                         true ? _VSTD::declval<_Tp>() : _VSTD::declval<_Up>()
2061                         )>::type type;
2062};
2063
2064template <class, class = void>
2065struct __common_type_impl {};
2066
2067// Clang provides variadic templates in C++03 as an extension.
2068#if !defined(_LIBCPP_CXX03_LANG) || defined(__clang__)
2069# define _LIBCPP_OPTIONAL_PACK(...) , __VA_ARGS__
2070template <class... Tp>
2071struct __common_types;
2072template <class... _Tp>
2073struct _LIBCPP_TEMPLATE_VIS common_type;
2074#else
2075# define _LIBCPP_OPTIONAL_PACK(...)
2076struct __no_arg;
2077template <class _Tp, class _Up, class = __no_arg>
2078struct __common_types;
2079template <class _Tp = __no_arg, class _Up = __no_arg, class _Vp = __no_arg,
2080          class _Unused = __no_arg>
2081struct common_type {
2082  static_assert(sizeof(_Unused) == 0,
2083                "common_type accepts at most 3 arguments in C++03");
2084};
2085#endif // _LIBCPP_CXX03_LANG
2086
2087template <class _Tp, class _Up>
2088struct __common_type_impl<
2089    __common_types<_Tp, _Up>,
2090    typename __void_t<typename common_type<_Tp, _Up>::type>::type>
2091{
2092  typedef typename common_type<_Tp, _Up>::type type;
2093};
2094
2095template <class _Tp, class _Up, class _Vp _LIBCPP_OPTIONAL_PACK(class... _Rest)>
2096struct __common_type_impl<
2097    __common_types<_Tp, _Up, _Vp _LIBCPP_OPTIONAL_PACK(_Rest...)>,
2098    typename __void_t<typename common_type<_Tp, _Up>::type>::type>
2099    : __common_type_impl<__common_types<typename common_type<_Tp, _Up>::type,
2100                                        _Vp _LIBCPP_OPTIONAL_PACK(_Rest...)> > {
2101};
2102
2103// bullet 1 - sizeof...(Tp) == 0
2104
2105template <>
2106struct _LIBCPP_TEMPLATE_VIS common_type<> {};
2107
2108// bullet 2 - sizeof...(Tp) == 1
2109
2110template <class _Tp>
2111struct _LIBCPP_TEMPLATE_VIS common_type<_Tp>
2112    : public common_type<_Tp, _Tp> {};
2113
2114// bullet 3 - sizeof...(Tp) == 2
2115
2116template <class _Tp, class _Up>
2117struct _LIBCPP_TEMPLATE_VIS common_type<_Tp, _Up>
2118    : conditional<
2119        _IsSame<_Tp, typename decay<_Tp>::type>::value && _IsSame<_Up, typename decay<_Up>::type>::value,
2120        __common_type2_imp<_Tp, _Up>,
2121        common_type<typename decay<_Tp>::type, typename decay<_Up>::type>
2122    >::type
2123{};
2124
2125// bullet 4 - sizeof...(Tp) > 2
2126
2127template <class _Tp, class _Up, class _Vp _LIBCPP_OPTIONAL_PACK(class... _Rest)>
2128struct _LIBCPP_TEMPLATE_VIS
2129    common_type<_Tp, _Up, _Vp _LIBCPP_OPTIONAL_PACK(_Rest...)>
2130    : __common_type_impl<
2131          __common_types<_Tp, _Up, _Vp _LIBCPP_OPTIONAL_PACK(_Rest...)> > {};
2132
2133#undef _LIBCPP_OPTIONAL_PACK
2134
2135#if _LIBCPP_STD_VER > 11
2136template <class ..._Tp> using common_type_t = typename common_type<_Tp...>::type;
2137#endif
2138
2139// is_assignable
2140
2141template<typename, typename _Tp> struct __select_2nd { typedef _LIBCPP_NODEBUG_TYPE _Tp type; };
2142
2143template <class _Tp, class _Arg>
2144typename __select_2nd<decltype((_VSTD::declval<_Tp>() = _VSTD::declval<_Arg>())), true_type>::type
2145__is_assignable_test(int);
2146
2147template <class, class>
2148false_type __is_assignable_test(...);
2149
2150
2151template <class _Tp, class _Arg, bool = is_void<_Tp>::value || is_void<_Arg>::value>
2152struct __is_assignable_imp
2153    : public decltype((_VSTD::__is_assignable_test<_Tp, _Arg>(0))) {};
2154
2155template <class _Tp, class _Arg>
2156struct __is_assignable_imp<_Tp, _Arg, true>
2157    : public false_type
2158{
2159};
2160
2161template <class _Tp, class _Arg>
2162struct is_assignable
2163    : public __is_assignable_imp<_Tp, _Arg> {};
2164
2165#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
2166template <class _Tp, class _Arg>
2167_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_assignable_v
2168    = is_assignable<_Tp, _Arg>::value;
2169#endif
2170
2171// is_copy_assignable
2172
2173template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_copy_assignable
2174    : public is_assignable<typename add_lvalue_reference<_Tp>::type,
2175                  typename add_lvalue_reference<typename add_const<_Tp>::type>::type> {};
2176
2177#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
2178template <class _Tp>
2179_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_copy_assignable_v
2180    = is_copy_assignable<_Tp>::value;
2181#endif
2182
2183// is_move_assignable
2184
2185template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_move_assignable
2186    : public is_assignable<typename add_lvalue_reference<_Tp>::type,
2187                           typename add_rvalue_reference<_Tp>::type> {};
2188
2189#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
2190template <class _Tp>
2191_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_move_assignable_v
2192    = is_move_assignable<_Tp>::value;
2193#endif
2194
2195// is_destructible
2196
2197//  if it's a reference, return true
2198//  if it's a function, return false
2199//  if it's   void,     return false
2200//  if it's an array of unknown bound, return false
2201//  Otherwise, return "std::declval<_Up&>().~_Up()" is well-formed
2202//    where _Up is remove_all_extents<_Tp>::type
2203
2204template <class>
2205struct __is_destructible_apply { typedef int type; };
2206
2207template <typename _Tp>
2208struct __is_destructor_wellformed {
2209    template <typename _Tp1>
2210    static char  __test (
2211        typename __is_destructible_apply<decltype(_VSTD::declval<_Tp1&>().~_Tp1())>::type
2212    );
2213
2214    template <typename _Tp1>
2215    static __two __test (...);
2216
2217    static const bool value = sizeof(__test<_Tp>(12)) == sizeof(char);
2218};
2219
2220template <class _Tp, bool>
2221struct __destructible_imp;
2222
2223template <class _Tp>
2224struct __destructible_imp<_Tp, false>
2225   : public _VSTD::integral_constant<bool,
2226        __is_destructor_wellformed<typename _VSTD::remove_all_extents<_Tp>::type>::value> {};
2227
2228template <class _Tp>
2229struct __destructible_imp<_Tp, true>
2230    : public _VSTD::true_type {};
2231
2232template <class _Tp, bool>
2233struct __destructible_false;
2234
2235template <class _Tp>
2236struct __destructible_false<_Tp, false> : public __destructible_imp<_Tp, _VSTD::is_reference<_Tp>::value> {};
2237
2238template <class _Tp>
2239struct __destructible_false<_Tp, true> : public _VSTD::false_type {};
2240
2241template <class _Tp>
2242struct is_destructible
2243    : public __destructible_false<_Tp, _VSTD::is_function<_Tp>::value> {};
2244
2245template <class _Tp>
2246struct is_destructible<_Tp[]>
2247    : public _VSTD::false_type {};
2248
2249template <>
2250struct is_destructible<void>
2251    : public _VSTD::false_type {};
2252
2253#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
2254template <class _Tp>
2255_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_destructible_v
2256    = is_destructible<_Tp>::value;
2257#endif
2258
2259// move
2260
2261template <class _Tp>
2262inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
2263typename remove_reference<_Tp>::type&&
2264move(_Tp&& __t) _NOEXCEPT
2265{
2266    typedef _LIBCPP_NODEBUG_TYPE typename remove_reference<_Tp>::type _Up;
2267    return static_cast<_Up&&>(__t);
2268}
2269
2270template <class _Tp>
2271inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
2272_Tp&&
2273forward(typename remove_reference<_Tp>::type& __t) _NOEXCEPT
2274{
2275    return static_cast<_Tp&&>(__t);
2276}
2277
2278template <class _Tp>
2279inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
2280_Tp&&
2281forward(typename remove_reference<_Tp>::type&& __t) _NOEXCEPT
2282{
2283    static_assert(!is_lvalue_reference<_Tp>::value,
2284                  "can not forward an rvalue as an lvalue");
2285    return static_cast<_Tp&&>(__t);
2286}
2287
2288template <class _Tp>
2289inline _LIBCPP_INLINE_VISIBILITY
2290typename decay<_Tp>::type
2291__decay_copy(_Tp&& __t)
2292{
2293    return _VSTD::forward<_Tp>(__t);
2294}
2295
2296template <class _MP, bool _IsMemberFunctionPtr, bool _IsMemberObjectPtr>
2297struct __member_pointer_traits_imp
2298{
2299};
2300
2301template <class _Rp, class _Class, class ..._Param>
2302struct __member_pointer_traits_imp<_Rp (_Class::*)(_Param...), true, false>
2303{
2304    typedef _Class _ClassType;
2305    typedef _Rp _ReturnType;
2306    typedef _Rp (_FnType) (_Param...);
2307};
2308
2309template <class _Rp, class _Class, class ..._Param>
2310struct __member_pointer_traits_imp<_Rp (_Class::*)(_Param..., ...), true, false>
2311{
2312    typedef _Class _ClassType;
2313    typedef _Rp _ReturnType;
2314    typedef _Rp (_FnType) (_Param..., ...);
2315};
2316
2317template <class _Rp, class _Class, class ..._Param>
2318struct __member_pointer_traits_imp<_Rp (_Class::*)(_Param...) const, true, false>
2319{
2320    typedef _Class const _ClassType;
2321    typedef _Rp _ReturnType;
2322    typedef _Rp (_FnType) (_Param...);
2323};
2324
2325template <class _Rp, class _Class, class ..._Param>
2326struct __member_pointer_traits_imp<_Rp (_Class::*)(_Param..., ...) const, true, false>
2327{
2328    typedef _Class const _ClassType;
2329    typedef _Rp _ReturnType;
2330    typedef _Rp (_FnType) (_Param..., ...);
2331};
2332
2333template <class _Rp, class _Class, class ..._Param>
2334struct __member_pointer_traits_imp<_Rp (_Class::*)(_Param...) volatile, true, false>
2335{
2336    typedef _Class volatile _ClassType;
2337    typedef _Rp _ReturnType;
2338    typedef _Rp (_FnType) (_Param...);
2339};
2340
2341template <class _Rp, class _Class, class ..._Param>
2342struct __member_pointer_traits_imp<_Rp (_Class::*)(_Param..., ...) volatile, true, false>
2343{
2344    typedef _Class volatile _ClassType;
2345    typedef _Rp _ReturnType;
2346    typedef _Rp (_FnType) (_Param..., ...);
2347};
2348
2349template <class _Rp, class _Class, class ..._Param>
2350struct __member_pointer_traits_imp<_Rp (_Class::*)(_Param...) const volatile, true, false>
2351{
2352    typedef _Class const volatile _ClassType;
2353    typedef _Rp _ReturnType;
2354    typedef _Rp (_FnType) (_Param...);
2355};
2356
2357template <class _Rp, class _Class, class ..._Param>
2358struct __member_pointer_traits_imp<_Rp (_Class::*)(_Param..., ...) const volatile, true, false>
2359{
2360    typedef _Class const volatile _ClassType;
2361    typedef _Rp _ReturnType;
2362    typedef _Rp (_FnType) (_Param..., ...);
2363};
2364
2365#if __has_feature(cxx_reference_qualified_functions) || defined(_LIBCPP_COMPILER_GCC)
2366
2367template <class _Rp, class _Class, class ..._Param>
2368struct __member_pointer_traits_imp<_Rp (_Class::*)(_Param...) &, true, false>
2369{
2370    typedef _Class& _ClassType;
2371    typedef _Rp _ReturnType;
2372    typedef _Rp (_FnType) (_Param...);
2373};
2374
2375template <class _Rp, class _Class, class ..._Param>
2376struct __member_pointer_traits_imp<_Rp (_Class::*)(_Param..., ...) &, true, false>
2377{
2378    typedef _Class& _ClassType;
2379    typedef _Rp _ReturnType;
2380    typedef _Rp (_FnType) (_Param..., ...);
2381};
2382
2383template <class _Rp, class _Class, class ..._Param>
2384struct __member_pointer_traits_imp<_Rp (_Class::*)(_Param...) const&, true, false>
2385{
2386    typedef _Class const& _ClassType;
2387    typedef _Rp _ReturnType;
2388    typedef _Rp (_FnType) (_Param...);
2389};
2390
2391template <class _Rp, class _Class, class ..._Param>
2392struct __member_pointer_traits_imp<_Rp (_Class::*)(_Param..., ...) const&, true, false>
2393{
2394    typedef _Class const& _ClassType;
2395    typedef _Rp _ReturnType;
2396    typedef _Rp (_FnType) (_Param..., ...);
2397};
2398
2399template <class _Rp, class _Class, class ..._Param>
2400struct __member_pointer_traits_imp<_Rp (_Class::*)(_Param...) volatile&, true, false>
2401{
2402    typedef _Class volatile& _ClassType;
2403    typedef _Rp _ReturnType;
2404    typedef _Rp (_FnType) (_Param...);
2405};
2406
2407template <class _Rp, class _Class, class ..._Param>
2408struct __member_pointer_traits_imp<_Rp (_Class::*)(_Param..., ...) volatile&, true, false>
2409{
2410    typedef _Class volatile& _ClassType;
2411    typedef _Rp _ReturnType;
2412    typedef _Rp (_FnType) (_Param..., ...);
2413};
2414
2415template <class _Rp, class _Class, class ..._Param>
2416struct __member_pointer_traits_imp<_Rp (_Class::*)(_Param...) const volatile&, true, false>
2417{
2418    typedef _Class const volatile& _ClassType;
2419    typedef _Rp _ReturnType;
2420    typedef _Rp (_FnType) (_Param...);
2421};
2422
2423template <class _Rp, class _Class, class ..._Param>
2424struct __member_pointer_traits_imp<_Rp (_Class::*)(_Param..., ...) const volatile&, true, false>
2425{
2426    typedef _Class const volatile& _ClassType;
2427    typedef _Rp _ReturnType;
2428    typedef _Rp (_FnType) (_Param..., ...);
2429};
2430
2431template <class _Rp, class _Class, class ..._Param>
2432struct __member_pointer_traits_imp<_Rp (_Class::*)(_Param...) &&, true, false>
2433{
2434    typedef _Class&& _ClassType;
2435    typedef _Rp _ReturnType;
2436    typedef _Rp (_FnType) (_Param...);
2437};
2438
2439template <class _Rp, class _Class, class ..._Param>
2440struct __member_pointer_traits_imp<_Rp (_Class::*)(_Param..., ...) &&, true, false>
2441{
2442    typedef _Class&& _ClassType;
2443    typedef _Rp _ReturnType;
2444    typedef _Rp (_FnType) (_Param..., ...);
2445};
2446
2447template <class _Rp, class _Class, class ..._Param>
2448struct __member_pointer_traits_imp<_Rp (_Class::*)(_Param...) const&&, true, false>
2449{
2450    typedef _Class const&& _ClassType;
2451    typedef _Rp _ReturnType;
2452    typedef _Rp (_FnType) (_Param...);
2453};
2454
2455template <class _Rp, class _Class, class ..._Param>
2456struct __member_pointer_traits_imp<_Rp (_Class::*)(_Param..., ...) const&&, true, false>
2457{
2458    typedef _Class const&& _ClassType;
2459    typedef _Rp _ReturnType;
2460    typedef _Rp (_FnType) (_Param..., ...);
2461};
2462
2463template <class _Rp, class _Class, class ..._Param>
2464struct __member_pointer_traits_imp<_Rp (_Class::*)(_Param...) volatile&&, true, false>
2465{
2466    typedef _Class volatile&& _ClassType;
2467    typedef _Rp _ReturnType;
2468    typedef _Rp (_FnType) (_Param...);
2469};
2470
2471template <class _Rp, class _Class, class ..._Param>
2472struct __member_pointer_traits_imp<_Rp (_Class::*)(_Param..., ...) volatile&&, true, false>
2473{
2474    typedef _Class volatile&& _ClassType;
2475    typedef _Rp _ReturnType;
2476    typedef _Rp (_FnType) (_Param..., ...);
2477};
2478
2479template <class _Rp, class _Class, class ..._Param>
2480struct __member_pointer_traits_imp<_Rp (_Class::*)(_Param...) const volatile&&, true, false>
2481{
2482    typedef _Class const volatile&& _ClassType;
2483    typedef _Rp _ReturnType;
2484    typedef _Rp (_FnType) (_Param...);
2485};
2486
2487template <class _Rp, class _Class, class ..._Param>
2488struct __member_pointer_traits_imp<_Rp (_Class::*)(_Param..., ...) const volatile&&, true, false>
2489{
2490    typedef _Class const volatile&& _ClassType;
2491    typedef _Rp _ReturnType;
2492    typedef _Rp (_FnType) (_Param..., ...);
2493};
2494
2495#endif  // __has_feature(cxx_reference_qualified_functions) || defined(_LIBCPP_COMPILER_GCC)
2496
2497
2498template <class _Rp, class _Class>
2499struct __member_pointer_traits_imp<_Rp _Class::*, false, true>
2500{
2501    typedef _Class _ClassType;
2502    typedef _Rp _ReturnType;
2503};
2504
2505template <class _MP>
2506struct __member_pointer_traits
2507    : public __member_pointer_traits_imp<typename remove_cv<_MP>::type,
2508                    is_member_function_pointer<_MP>::value,
2509                    is_member_object_pointer<_MP>::value>
2510{
2511//     typedef ... _ClassType;
2512//     typedef ... _ReturnType;
2513//     typedef ... _FnType;
2514};
2515
2516
2517template <class _DecayedFp>
2518struct __member_pointer_class_type {};
2519
2520template <class _Ret, class _ClassType>
2521struct __member_pointer_class_type<_Ret _ClassType::*> {
2522  typedef _ClassType type;
2523};
2524
2525// result_of
2526
2527template <class _Callable> class result_of;
2528
2529#ifdef _LIBCPP_HAS_NO_VARIADICS
2530
2531template <class _Fn, bool, bool>
2532class __result_of
2533{
2534};
2535
2536template <class _Fn>
2537class __result_of<_Fn(), true, false>
2538{
2539public:
2540    typedef decltype(declval<_Fn>()()) type;
2541};
2542
2543template <class _Fn, class _A0>
2544class __result_of<_Fn(_A0), true, false>
2545{
2546public:
2547    typedef decltype(declval<_Fn>()(declval<_A0>())) type;
2548};
2549
2550template <class _Fn, class _A0, class _A1>
2551class __result_of<_Fn(_A0, _A1), true, false>
2552{
2553public:
2554    typedef decltype(declval<_Fn>()(declval<_A0>(), declval<_A1>())) type;
2555};
2556
2557template <class _Fn, class _A0, class _A1, class _A2>
2558class __result_of<_Fn(_A0, _A1, _A2), true, false>
2559{
2560public:
2561    typedef decltype(declval<_Fn>()(declval<_A0>(), declval<_A1>(), declval<_A2>())) type;
2562};
2563
2564template <class _MP, class _Tp, bool _IsMemberFunctionPtr>
2565struct __result_of_mp;
2566
2567// member function pointer
2568
2569template <class _MP, class _Tp>
2570struct __result_of_mp<_MP, _Tp, true>
2571    : public __identity<typename __member_pointer_traits<_MP>::_ReturnType>
2572{
2573};
2574
2575// member data pointer
2576
2577template <class _MP, class _Tp, bool>
2578struct __result_of_mdp;
2579
2580template <class _Rp, class _Class, class _Tp>
2581struct __result_of_mdp<_Rp _Class::*, _Tp, false>
2582{
2583    typedef typename __apply_cv<decltype(*_VSTD::declval<_Tp>()), _Rp>::type& type;
2584};
2585
2586template <class _Rp, class _Class, class _Tp>
2587struct __result_of_mdp<_Rp _Class::*, _Tp, true>
2588{
2589    typedef typename __apply_cv<_Tp, _Rp>::type& type;
2590};
2591
2592template <class _Rp, class _Class, class _Tp>
2593struct __result_of_mp<_Rp _Class::*, _Tp, false>
2594    : public __result_of_mdp<_Rp _Class::*, _Tp,
2595            is_base_of<_Class, typename remove_reference<_Tp>::type>::value>
2596{
2597};
2598
2599
2600
2601template <class _Fn, class _Tp>
2602class __result_of<_Fn(_Tp), false, true>  // _Fn must be member pointer
2603    : public __result_of_mp<typename remove_reference<_Fn>::type,
2604                            _Tp,
2605                            is_member_function_pointer<typename remove_reference<_Fn>::type>::value>
2606{
2607};
2608
2609template <class _Fn, class _Tp, class _A0>
2610class __result_of<_Fn(_Tp, _A0), false, true>  // _Fn must be member pointer
2611    : public __result_of_mp<typename remove_reference<_Fn>::type,
2612                            _Tp,
2613                            is_member_function_pointer<typename remove_reference<_Fn>::type>::value>
2614{
2615};
2616
2617template <class _Fn, class _Tp, class _A0, class _A1>
2618class __result_of<_Fn(_Tp, _A0, _A1), false, true>  // _Fn must be member pointer
2619    : public __result_of_mp<typename remove_reference<_Fn>::type,
2620                            _Tp,
2621                            is_member_function_pointer<typename remove_reference<_Fn>::type>::value>
2622{
2623};
2624
2625template <class _Fn, class _Tp, class _A0, class _A1, class _A2>
2626class __result_of<_Fn(_Tp, _A0, _A1, _A2), false, true>  // _Fn must be member pointer
2627    : public __result_of_mp<typename remove_reference<_Fn>::type,
2628                            _Tp,
2629                            is_member_function_pointer<typename remove_reference<_Fn>::type>::value>
2630{
2631};
2632
2633// result_of
2634
2635template <class _Fn>
2636class _LIBCPP_TEMPLATE_VIS result_of<_Fn()>
2637    : public __result_of<_Fn(),
2638                         is_class<typename remove_reference<_Fn>::type>::value ||
2639                         is_function<typename remove_pointer<typename remove_reference<_Fn>::type>::type>::value,
2640                         is_member_pointer<typename remove_reference<_Fn>::type>::value
2641                        >
2642{
2643};
2644
2645template <class _Fn, class _A0>
2646class _LIBCPP_TEMPLATE_VIS result_of<_Fn(_A0)>
2647    : public __result_of<_Fn(_A0),
2648                         is_class<typename remove_reference<_Fn>::type>::value ||
2649                         is_function<typename remove_pointer<typename remove_reference<_Fn>::type>::type>::value,
2650                         is_member_pointer<typename remove_reference<_Fn>::type>::value
2651                        >
2652{
2653};
2654
2655template <class _Fn, class _A0, class _A1>
2656class _LIBCPP_TEMPLATE_VIS result_of<_Fn(_A0, _A1)>
2657    : public __result_of<_Fn(_A0, _A1),
2658                         is_class<typename remove_reference<_Fn>::type>::value ||
2659                         is_function<typename remove_pointer<typename remove_reference<_Fn>::type>::type>::value,
2660                         is_member_pointer<typename remove_reference<_Fn>::type>::value
2661                        >
2662{
2663};
2664
2665template <class _Fn, class _A0, class _A1, class _A2>
2666class _LIBCPP_TEMPLATE_VIS result_of<_Fn(_A0, _A1, _A2)>
2667    : public __result_of<_Fn(_A0, _A1, _A2),
2668                         is_class<typename remove_reference<_Fn>::type>::value ||
2669                         is_function<typename remove_pointer<typename remove_reference<_Fn>::type>::type>::value,
2670                         is_member_pointer<typename remove_reference<_Fn>::type>::value
2671                        >
2672{
2673};
2674
2675#endif  // _LIBCPP_HAS_NO_VARIADICS
2676
2677// template <class T, class... Args> struct is_constructible;
2678
2679namespace __is_construct
2680{
2681struct __nat {};
2682}
2683
2684#if !defined(_LIBCPP_CXX03_LANG) && (!__has_feature(is_constructible) || \
2685    defined(_LIBCPP_TESTING_FALLBACK_IS_CONSTRUCTIBLE))
2686
2687template <class _Tp, class... _Args>
2688struct __libcpp_is_constructible;
2689
2690template <class _To, class _From>
2691struct __is_invalid_base_to_derived_cast {
2692  static_assert(is_reference<_To>::value, "Wrong specialization");
2693  using _RawFrom = __uncvref_t<_From>;
2694  using _RawTo = __uncvref_t<_To>;
2695  static const bool value = _And<
2696        _IsNotSame<_RawFrom, _RawTo>,
2697        is_base_of<_RawFrom, _RawTo>,
2698        _Not<__libcpp_is_constructible<_RawTo, _From>>
2699  >::value;
2700};
2701
2702template <class _To, class _From>
2703struct __is_invalid_lvalue_to_rvalue_cast : false_type {
2704  static_assert(is_reference<_To>::value, "Wrong specialization");
2705};
2706
2707template <class _ToRef, class _FromRef>
2708struct __is_invalid_lvalue_to_rvalue_cast<_ToRef&&, _FromRef&> {
2709  using _RawFrom = __uncvref_t<_FromRef>;
2710  using _RawTo = __uncvref_t<_ToRef>;
2711  static const bool value = _And<
2712      _Not<is_function<_RawTo>>,
2713      _Or<
2714        _IsSame<_RawFrom, _RawTo>,
2715        is_base_of<_RawTo, _RawFrom>>
2716    >::value;
2717};
2718
2719struct __is_constructible_helper
2720{
2721    template <class _To>
2722    static void __eat(_To);
2723
2724    // This overload is needed to work around a Clang bug that disallows
2725    // static_cast<T&&>(e) for non-reference-compatible types.
2726    // Example: static_cast<int&&>(declval<double>());
2727    // NOTE: The static_cast implementation below is required to support
2728    //  classes with explicit conversion operators.
2729    template <class _To, class _From,
2730              class = decltype(__eat<_To>(_VSTD::declval<_From>()))>
2731    static true_type __test_cast(int);
2732
2733    template <class _To, class _From,
2734              class = decltype(static_cast<_To>(_VSTD::declval<_From>()))>
2735    static integral_constant<bool,
2736        !__is_invalid_base_to_derived_cast<_To, _From>::value &&
2737        !__is_invalid_lvalue_to_rvalue_cast<_To, _From>::value
2738    > __test_cast(long);
2739
2740    template <class, class>
2741    static false_type __test_cast(...);
2742
2743    template <class _Tp, class ..._Args,
2744        class = decltype(_Tp(_VSTD::declval<_Args>()...))>
2745    static true_type __test_nary(int);
2746    template <class _Tp, class...>
2747    static false_type __test_nary(...);
2748
2749    template <class _Tp, class _A0, class = decltype(::new _Tp(_VSTD::declval<_A0>()))>
2750    static is_destructible<_Tp> __test_unary(int);
2751    template <class, class>
2752    static false_type __test_unary(...);
2753};
2754
2755template <class _Tp, bool = is_void<_Tp>::value>
2756struct __is_default_constructible
2757    : decltype(__is_constructible_helper::__test_nary<_Tp>(0))
2758{};
2759
2760template <class _Tp>
2761struct __is_default_constructible<_Tp, true> : false_type {};
2762
2763template <class _Tp>
2764struct __is_default_constructible<_Tp[], false> : false_type {};
2765
2766template <class _Tp, size_t _Nx>
2767struct __is_default_constructible<_Tp[_Nx], false>
2768    : __is_default_constructible<typename remove_all_extents<_Tp>::type>  {};
2769
2770template <class _Tp, class... _Args>
2771struct __libcpp_is_constructible
2772{
2773  static_assert(sizeof...(_Args) > 1, "Wrong specialization");
2774  typedef decltype(__is_constructible_helper::__test_nary<_Tp, _Args...>(0))
2775      type;
2776};
2777
2778template <class _Tp>
2779struct __libcpp_is_constructible<_Tp> : __is_default_constructible<_Tp> {};
2780
2781template <class _Tp, class _A0>
2782struct __libcpp_is_constructible<_Tp, _A0>
2783    : public decltype(__is_constructible_helper::__test_unary<_Tp, _A0>(0))
2784{};
2785
2786template <class _Tp, class _A0>
2787struct __libcpp_is_constructible<_Tp&, _A0>
2788    : public decltype(__is_constructible_helper::
2789    __test_cast<_Tp&, _A0>(0))
2790{};
2791
2792template <class _Tp, class _A0>
2793struct __libcpp_is_constructible<_Tp&&, _A0>
2794    : public decltype(__is_constructible_helper::
2795    __test_cast<_Tp&&, _A0>(0))
2796{};
2797
2798#endif
2799
2800#if __has_feature(is_constructible)
2801template <class _Tp, class ..._Args>
2802struct _LIBCPP_TEMPLATE_VIS is_constructible
2803    : public integral_constant<bool, __is_constructible(_Tp, _Args...)>
2804    {};
2805#else
2806template <class _Tp, class... _Args>
2807struct _LIBCPP_TEMPLATE_VIS is_constructible
2808    : public __libcpp_is_constructible<_Tp, _Args...>::type {};
2809#endif
2810
2811#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
2812template <class _Tp, class ..._Args>
2813_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_constructible_v
2814    = is_constructible<_Tp, _Args...>::value;
2815#endif
2816
2817// is_default_constructible
2818
2819template <class _Tp>
2820struct _LIBCPP_TEMPLATE_VIS is_default_constructible
2821    : public is_constructible<_Tp>
2822    {};
2823
2824#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
2825template <class _Tp>
2826_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_default_constructible_v
2827    = is_default_constructible<_Tp>::value;
2828#endif
2829
2830#ifndef _LIBCPP_CXX03_LANG
2831// First of all, we can't implement this check in C++03 mode because the {}
2832// default initialization syntax isn't valid.
2833// Second, we implement the trait in a funny manner with two defaulted template
2834// arguments to workaround Clang's PR43454.
2835template <class _Tp>
2836void __test_implicit_default_constructible(_Tp);
2837
2838template <class _Tp, class = void, bool = is_default_constructible<_Tp>::value>
2839struct __is_implicitly_default_constructible
2840    : false_type
2841{ };
2842
2843template <class _Tp>
2844struct __is_implicitly_default_constructible<_Tp, decltype(__test_implicit_default_constructible<_Tp const&>({})), true>
2845    : true_type
2846{ };
2847
2848template <class _Tp>
2849struct __is_implicitly_default_constructible<_Tp, decltype(__test_implicit_default_constructible<_Tp const&>({})), false>
2850    : false_type
2851{ };
2852#endif // !C++03
2853
2854// is_copy_constructible
2855
2856template <class _Tp>
2857struct _LIBCPP_TEMPLATE_VIS is_copy_constructible
2858    : public is_constructible<_Tp,
2859                  typename add_lvalue_reference<typename add_const<_Tp>::type>::type> {};
2860
2861#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
2862template <class _Tp>
2863_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_copy_constructible_v
2864    = is_copy_constructible<_Tp>::value;
2865#endif
2866
2867// is_move_constructible
2868
2869template <class _Tp>
2870struct _LIBCPP_TEMPLATE_VIS is_move_constructible
2871    : public is_constructible<_Tp, typename add_rvalue_reference<_Tp>::type>
2872    {};
2873
2874#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
2875template <class _Tp>
2876_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_move_constructible_v
2877    = is_move_constructible<_Tp>::value;
2878#endif
2879
2880// is_trivially_constructible
2881
2882#if __has_feature(is_trivially_constructible) || _GNUC_VER >= 501
2883
2884template <class _Tp, class... _Args>
2885struct _LIBCPP_TEMPLATE_VIS is_trivially_constructible
2886    : integral_constant<bool, __is_trivially_constructible(_Tp, _Args...)>
2887{
2888};
2889
2890#else  // !__has_feature(is_trivially_constructible)
2891
2892template <class _Tp, class... _Args>
2893struct _LIBCPP_TEMPLATE_VIS is_trivially_constructible
2894    : false_type
2895{
2896};
2897
2898template <class _Tp>
2899struct _LIBCPP_TEMPLATE_VIS is_trivially_constructible<_Tp>
2900#if __has_feature(has_trivial_constructor) || defined(_LIBCPP_COMPILER_GCC)
2901    : integral_constant<bool, __has_trivial_constructor(_Tp)>
2902#else
2903    : integral_constant<bool, is_scalar<_Tp>::value>
2904#endif
2905{
2906};
2907
2908template <class _Tp>
2909struct _LIBCPP_TEMPLATE_VIS is_trivially_constructible<_Tp, _Tp&&>
2910    : integral_constant<bool, is_scalar<_Tp>::value>
2911{
2912};
2913
2914template <class _Tp>
2915struct _LIBCPP_TEMPLATE_VIS is_trivially_constructible<_Tp, const _Tp&>
2916    : integral_constant<bool, is_scalar<_Tp>::value>
2917{
2918};
2919
2920template <class _Tp>
2921struct _LIBCPP_TEMPLATE_VIS is_trivially_constructible<_Tp, _Tp&>
2922    : integral_constant<bool, is_scalar<_Tp>::value>
2923{
2924};
2925
2926#endif  // !__has_feature(is_trivially_constructible)
2927
2928
2929#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
2930template <class _Tp, class... _Args>
2931_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_trivially_constructible_v
2932    = is_trivially_constructible<_Tp, _Args...>::value;
2933#endif
2934
2935// is_trivially_default_constructible
2936
2937template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_trivially_default_constructible
2938    : public is_trivially_constructible<_Tp>
2939    {};
2940
2941#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
2942template <class _Tp>
2943_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_trivially_default_constructible_v
2944    = is_trivially_default_constructible<_Tp>::value;
2945#endif
2946
2947// is_trivially_copy_constructible
2948
2949template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_trivially_copy_constructible
2950    : public is_trivially_constructible<_Tp, typename add_lvalue_reference<const _Tp>::type>
2951    {};
2952
2953#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
2954template <class _Tp>
2955_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_trivially_copy_constructible_v
2956    = is_trivially_copy_constructible<_Tp>::value;
2957#endif
2958
2959// is_trivially_move_constructible
2960
2961template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_trivially_move_constructible
2962    : public is_trivially_constructible<_Tp, typename add_rvalue_reference<_Tp>::type>
2963    {};
2964
2965#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
2966template <class _Tp>
2967_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_trivially_move_constructible_v
2968    = is_trivially_move_constructible<_Tp>::value;
2969#endif
2970
2971// is_trivially_assignable
2972
2973#if __has_feature(is_trivially_assignable) || _GNUC_VER >= 501
2974
2975template <class _Tp, class _Arg>
2976struct is_trivially_assignable
2977    : integral_constant<bool, __is_trivially_assignable(_Tp, _Arg)>
2978{
2979};
2980
2981#else  // !__has_feature(is_trivially_assignable)
2982
2983template <class _Tp, class _Arg>
2984struct is_trivially_assignable
2985    : public false_type {};
2986
2987template <class _Tp>
2988struct is_trivially_assignable<_Tp&, _Tp>
2989    : integral_constant<bool, is_scalar<_Tp>::value> {};
2990
2991template <class _Tp>
2992struct is_trivially_assignable<_Tp&, _Tp&>
2993    : integral_constant<bool, is_scalar<_Tp>::value> {};
2994
2995template <class _Tp>
2996struct is_trivially_assignable<_Tp&, const _Tp&>
2997    : integral_constant<bool, is_scalar<_Tp>::value> {};
2998
2999template <class _Tp>
3000struct is_trivially_assignable<_Tp&, _Tp&&>
3001    : integral_constant<bool, is_scalar<_Tp>::value> {};
3002
3003#endif  // !__has_feature(is_trivially_assignable)
3004
3005#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
3006template <class _Tp, class _Arg>
3007_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_trivially_assignable_v
3008    = is_trivially_assignable<_Tp, _Arg>::value;
3009#endif
3010
3011// is_trivially_copy_assignable
3012
3013template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_trivially_copy_assignable
3014    : public is_trivially_assignable<typename add_lvalue_reference<_Tp>::type,
3015                  typename add_lvalue_reference<typename add_const<_Tp>::type>::type> {};
3016
3017#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
3018template <class _Tp>
3019_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_trivially_copy_assignable_v
3020    = is_trivially_copy_assignable<_Tp>::value;
3021#endif
3022
3023// is_trivially_move_assignable
3024
3025template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_trivially_move_assignable
3026    : public is_trivially_assignable<typename add_lvalue_reference<_Tp>::type,
3027                                     typename add_rvalue_reference<_Tp>::type>
3028    {};
3029
3030#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
3031template <class _Tp>
3032_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_trivially_move_assignable_v
3033    = is_trivially_move_assignable<_Tp>::value;
3034#endif
3035
3036// is_trivially_destructible
3037
3038#if __has_keyword(__is_trivially_destructible)
3039
3040template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_trivially_destructible
3041    : public integral_constant<bool, __is_trivially_destructible(_Tp)> {};
3042
3043#elif __has_feature(has_trivial_destructor) || defined(_LIBCPP_COMPILER_GCC)
3044
3045template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_trivially_destructible
3046    : public integral_constant<bool, is_destructible<_Tp>::value && __has_trivial_destructor(_Tp)> {};
3047
3048#else
3049
3050template <class _Tp> struct __libcpp_trivial_destructor
3051    : public integral_constant<bool, is_scalar<_Tp>::value ||
3052                                     is_reference<_Tp>::value> {};
3053
3054template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_trivially_destructible
3055    : public __libcpp_trivial_destructor<typename remove_all_extents<_Tp>::type> {};
3056
3057template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_trivially_destructible<_Tp[]>
3058    : public false_type {};
3059
3060#endif
3061
3062#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
3063template <class _Tp>
3064_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_trivially_destructible_v
3065    = is_trivially_destructible<_Tp>::value;
3066#endif
3067
3068// is_nothrow_constructible
3069
3070#if __has_keyword(__is_nothrow_constructible)
3071
3072template <class _Tp, class... _Args>
3073struct _LIBCPP_TEMPLATE_VIS is_nothrow_constructible
3074    : public integral_constant<bool, __is_nothrow_constructible(_Tp, _Args...)> {};
3075
3076#else
3077
3078template <bool, bool, class _Tp, class... _Args> struct __libcpp_is_nothrow_constructible;
3079
3080template <class _Tp, class... _Args>
3081struct __libcpp_is_nothrow_constructible</*is constructible*/true, /*is reference*/false, _Tp, _Args...>
3082    : public integral_constant<bool, noexcept(_Tp(declval<_Args>()...))>
3083{
3084};
3085
3086template <class _Tp>
3087void __implicit_conversion_to(_Tp) noexcept { }
3088
3089template <class _Tp, class _Arg>
3090struct __libcpp_is_nothrow_constructible</*is constructible*/true, /*is reference*/true, _Tp, _Arg>
3091    : public integral_constant<bool, noexcept(__implicit_conversion_to<_Tp>(declval<_Arg>()))>
3092{
3093};
3094
3095template <class _Tp, bool _IsReference, class... _Args>
3096struct __libcpp_is_nothrow_constructible</*is constructible*/false, _IsReference, _Tp, _Args...>
3097    : public false_type
3098{
3099};
3100
3101template <class _Tp, class... _Args>
3102struct _LIBCPP_TEMPLATE_VIS is_nothrow_constructible
3103    : __libcpp_is_nothrow_constructible<is_constructible<_Tp, _Args...>::value, is_reference<_Tp>::value, _Tp, _Args...>
3104{
3105};
3106
3107template <class _Tp, size_t _Ns>
3108struct _LIBCPP_TEMPLATE_VIS is_nothrow_constructible<_Tp[_Ns]>
3109    : __libcpp_is_nothrow_constructible<is_constructible<_Tp>::value, is_reference<_Tp>::value, _Tp>
3110{
3111};
3112
3113#endif  // _LIBCPP_HAS_NO_NOEXCEPT
3114
3115
3116#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
3117template <class _Tp, class ..._Args>
3118_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_nothrow_constructible_v
3119    = is_nothrow_constructible<_Tp, _Args...>::value;
3120#endif
3121
3122// is_nothrow_default_constructible
3123
3124template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_nothrow_default_constructible
3125    : public is_nothrow_constructible<_Tp>
3126    {};
3127
3128#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
3129template <class _Tp>
3130_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_nothrow_default_constructible_v
3131    = is_nothrow_default_constructible<_Tp>::value;
3132#endif
3133
3134// is_nothrow_copy_constructible
3135
3136template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_nothrow_copy_constructible
3137    : public is_nothrow_constructible<_Tp,
3138                  typename add_lvalue_reference<typename add_const<_Tp>::type>::type> {};
3139
3140#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
3141template <class _Tp>
3142_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_nothrow_copy_constructible_v
3143    = is_nothrow_copy_constructible<_Tp>::value;
3144#endif
3145
3146// is_nothrow_move_constructible
3147
3148template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_nothrow_move_constructible
3149    : public is_nothrow_constructible<_Tp, typename add_rvalue_reference<_Tp>::type>
3150    {};
3151
3152#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
3153template <class _Tp>
3154_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_nothrow_move_constructible_v
3155    = is_nothrow_move_constructible<_Tp>::value;
3156#endif
3157
3158// is_nothrow_assignable
3159
3160#if __has_keyword(__is_nothrow_assignable)
3161
3162template <class _Tp, class _Arg>
3163struct _LIBCPP_TEMPLATE_VIS is_nothrow_assignable
3164    : public integral_constant<bool, __is_nothrow_assignable(_Tp, _Arg)> {};
3165
3166#else
3167
3168template <bool, class _Tp, class _Arg> struct __libcpp_is_nothrow_assignable;
3169
3170template <class _Tp, class _Arg>
3171struct __libcpp_is_nothrow_assignable<false, _Tp, _Arg>
3172    : public false_type
3173{
3174};
3175
3176template <class _Tp, class _Arg>
3177struct __libcpp_is_nothrow_assignable<true, _Tp, _Arg>
3178    : public integral_constant<bool, noexcept(_VSTD::declval<_Tp>() = _VSTD::declval<_Arg>()) >
3179{
3180};
3181
3182template <class _Tp, class _Arg>
3183struct _LIBCPP_TEMPLATE_VIS is_nothrow_assignable
3184    : public __libcpp_is_nothrow_assignable<is_assignable<_Tp, _Arg>::value, _Tp, _Arg>
3185{
3186};
3187
3188#endif  // _LIBCPP_HAS_NO_NOEXCEPT
3189
3190#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
3191template <class _Tp, class _Arg>
3192_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_nothrow_assignable_v
3193    = is_nothrow_assignable<_Tp, _Arg>::value;
3194#endif
3195
3196// is_nothrow_copy_assignable
3197
3198template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_nothrow_copy_assignable
3199    : public is_nothrow_assignable<typename add_lvalue_reference<_Tp>::type,
3200                  typename add_lvalue_reference<typename add_const<_Tp>::type>::type> {};
3201
3202#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
3203template <class _Tp>
3204_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_nothrow_copy_assignable_v
3205    = is_nothrow_copy_assignable<_Tp>::value;
3206#endif
3207
3208// is_nothrow_move_assignable
3209
3210template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_nothrow_move_assignable
3211    : public is_nothrow_assignable<typename add_lvalue_reference<_Tp>::type,
3212                                     typename add_rvalue_reference<_Tp>::type>
3213    {};
3214
3215#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
3216template <class _Tp>
3217_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_nothrow_move_assignable_v
3218    = is_nothrow_move_assignable<_Tp>::value;
3219#endif
3220
3221// is_nothrow_destructible
3222
3223#if !defined(_LIBCPP_CXX03_LANG)
3224
3225template <bool, class _Tp> struct __libcpp_is_nothrow_destructible;
3226
3227template <class _Tp>
3228struct __libcpp_is_nothrow_destructible<false, _Tp>
3229    : public false_type
3230{
3231};
3232
3233template <class _Tp>
3234struct __libcpp_is_nothrow_destructible<true, _Tp>
3235    : public integral_constant<bool, noexcept(_VSTD::declval<_Tp>().~_Tp()) >
3236{
3237};
3238
3239template <class _Tp>
3240struct _LIBCPP_TEMPLATE_VIS is_nothrow_destructible
3241    : public __libcpp_is_nothrow_destructible<is_destructible<_Tp>::value, _Tp>
3242{
3243};
3244
3245template <class _Tp, size_t _Ns>
3246struct _LIBCPP_TEMPLATE_VIS is_nothrow_destructible<_Tp[_Ns]>
3247    : public is_nothrow_destructible<_Tp>
3248{
3249};
3250
3251template <class _Tp>
3252struct _LIBCPP_TEMPLATE_VIS is_nothrow_destructible<_Tp&>
3253    : public true_type
3254{
3255};
3256
3257template <class _Tp>
3258struct _LIBCPP_TEMPLATE_VIS is_nothrow_destructible<_Tp&&>
3259    : public true_type
3260{
3261};
3262
3263#else
3264
3265template <class _Tp> struct __libcpp_nothrow_destructor
3266    : public integral_constant<bool, is_scalar<_Tp>::value ||
3267                                     is_reference<_Tp>::value> {};
3268
3269template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_nothrow_destructible
3270    : public __libcpp_nothrow_destructor<typename remove_all_extents<_Tp>::type> {};
3271
3272template <class _Tp>
3273struct _LIBCPP_TEMPLATE_VIS is_nothrow_destructible<_Tp[]>
3274    : public false_type {};
3275
3276#endif
3277
3278#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
3279template <class _Tp>
3280_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_nothrow_destructible_v
3281    = is_nothrow_destructible<_Tp>::value;
3282#endif
3283
3284// is_pod
3285
3286#if __has_feature(is_pod) || defined(_LIBCPP_COMPILER_GCC)
3287
3288template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_pod
3289    : public integral_constant<bool, __is_pod(_Tp)> {};
3290
3291#else
3292
3293template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_pod
3294    : public integral_constant<bool, is_trivially_default_constructible<_Tp>::value   &&
3295                                     is_trivially_copy_constructible<_Tp>::value      &&
3296                                     is_trivially_copy_assignable<_Tp>::value    &&
3297                                     is_trivially_destructible<_Tp>::value> {};
3298
3299#endif
3300
3301#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
3302template <class _Tp>
3303_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_pod_v
3304    = is_pod<_Tp>::value;
3305#endif
3306
3307// is_literal_type;
3308
3309template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_literal_type
3310    : public integral_constant<bool, __is_literal_type(_Tp)>
3311    {};
3312
3313#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
3314template <class _Tp>
3315_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_literal_type_v
3316    = is_literal_type<_Tp>::value;
3317#endif
3318
3319// is_standard_layout;
3320
3321template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_standard_layout
3322#if __has_feature(is_standard_layout) || defined(_LIBCPP_COMPILER_GCC)
3323    : public integral_constant<bool, __is_standard_layout(_Tp)>
3324#else
3325    : integral_constant<bool, is_scalar<typename remove_all_extents<_Tp>::type>::value>
3326#endif
3327    {};
3328
3329#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
3330template <class _Tp>
3331_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_standard_layout_v
3332    = is_standard_layout<_Tp>::value;
3333#endif
3334
3335// is_trivially_copyable;
3336
3337template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_trivially_copyable
3338#if __has_feature(is_trivially_copyable)
3339    : public integral_constant<bool, __is_trivially_copyable(_Tp)>
3340#elif _GNUC_VER >= 501
3341    : public integral_constant<bool, !is_volatile<_Tp>::value && __is_trivially_copyable(_Tp)>
3342#else
3343    : integral_constant<bool, is_scalar<typename remove_all_extents<_Tp>::type>::value>
3344#endif
3345    {};
3346
3347#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
3348template <class _Tp>
3349_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_trivially_copyable_v
3350    = is_trivially_copyable<_Tp>::value;
3351#endif
3352
3353// is_trivial;
3354
3355template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_trivial
3356#if __has_feature(is_trivial) || defined(_LIBCPP_COMPILER_GCC)
3357    : public integral_constant<bool, __is_trivial(_Tp)>
3358#else
3359    : integral_constant<bool, is_trivially_copyable<_Tp>::value &&
3360                                 is_trivially_default_constructible<_Tp>::value>
3361#endif
3362    {};
3363
3364#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
3365template <class _Tp>
3366_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_trivial_v
3367    = is_trivial<_Tp>::value;
3368#endif
3369
3370template <class _Tp> struct __is_reference_wrapper_impl : public false_type {};
3371template <class _Tp> struct __is_reference_wrapper_impl<reference_wrapper<_Tp> > : public true_type {};
3372template <class _Tp> struct __is_reference_wrapper
3373    : public __is_reference_wrapper_impl<typename remove_cv<_Tp>::type> {};
3374
3375#ifndef _LIBCPP_CXX03_LANG
3376
3377template <class _Fp, class _A0,
3378         class _DecayFp = typename decay<_Fp>::type,
3379         class _DecayA0 = typename decay<_A0>::type,
3380         class _ClassT = typename __member_pointer_class_type<_DecayFp>::type>
3381using __enable_if_bullet1 = typename enable_if
3382    <
3383        is_member_function_pointer<_DecayFp>::value
3384        && is_base_of<_ClassT, _DecayA0>::value
3385    >::type;
3386
3387template <class _Fp, class _A0,
3388         class _DecayFp = typename decay<_Fp>::type,
3389         class _DecayA0 = typename decay<_A0>::type>
3390using __enable_if_bullet2 = typename enable_if
3391    <
3392        is_member_function_pointer<_DecayFp>::value
3393        && __is_reference_wrapper<_DecayA0>::value
3394    >::type;
3395
3396template <class _Fp, class _A0,
3397         class _DecayFp = typename decay<_Fp>::type,
3398         class _DecayA0 = typename decay<_A0>::type,
3399         class _ClassT = typename __member_pointer_class_type<_DecayFp>::type>
3400using __enable_if_bullet3 = typename enable_if
3401    <
3402        is_member_function_pointer<_DecayFp>::value
3403        && !is_base_of<_ClassT, _DecayA0>::value
3404        && !__is_reference_wrapper<_DecayA0>::value
3405    >::type;
3406
3407template <class _Fp, class _A0,
3408         class _DecayFp = typename decay<_Fp>::type,
3409         class _DecayA0 = typename decay<_A0>::type,
3410         class _ClassT = typename __member_pointer_class_type<_DecayFp>::type>
3411using __enable_if_bullet4 = typename enable_if
3412    <
3413        is_member_object_pointer<_DecayFp>::value
3414        && is_base_of<_ClassT, _DecayA0>::value
3415    >::type;
3416
3417template <class _Fp, class _A0,
3418         class _DecayFp = typename decay<_Fp>::type,
3419         class _DecayA0 = typename decay<_A0>::type>
3420using __enable_if_bullet5 = typename enable_if
3421    <
3422        is_member_object_pointer<_DecayFp>::value
3423        && __is_reference_wrapper<_DecayA0>::value
3424    >::type;
3425
3426template <class _Fp, class _A0,
3427         class _DecayFp = typename decay<_Fp>::type,
3428         class _DecayA0 = typename decay<_A0>::type,
3429         class _ClassT = typename __member_pointer_class_type<_DecayFp>::type>
3430using __enable_if_bullet6 = typename enable_if
3431    <
3432        is_member_object_pointer<_DecayFp>::value
3433        && !is_base_of<_ClassT, _DecayA0>::value
3434        && !__is_reference_wrapper<_DecayA0>::value
3435    >::type;
3436
3437// __invoke forward declarations
3438
3439// fall back - none of the bullets
3440
3441#define _LIBCPP_INVOKE_RETURN(...) \
3442    noexcept(noexcept(__VA_ARGS__)) -> decltype(__VA_ARGS__) \
3443    { return __VA_ARGS__; }
3444
3445template <class ..._Args>
3446auto __invoke(__any, _Args&& ...__args) -> __nat;
3447
3448template <class ..._Args>
3449auto __invoke_constexpr(__any, _Args&& ...__args) -> __nat;
3450
3451// bullets 1, 2 and 3
3452
3453template <class _Fp, class _A0, class ..._Args,
3454          class = __enable_if_bullet1<_Fp, _A0>>
3455inline _LIBCPP_INLINE_VISIBILITY
3456auto
3457__invoke(_Fp&& __f, _A0&& __a0, _Args&& ...__args)
3458_LIBCPP_INVOKE_RETURN((_VSTD::forward<_A0>(__a0).*__f)(_VSTD::forward<_Args>(__args)...))
3459
3460template <class _Fp, class _A0, class ..._Args,
3461          class = __enable_if_bullet1<_Fp, _A0>>
3462inline _LIBCPP_INLINE_VISIBILITY
3463_LIBCPP_CONSTEXPR auto
3464__invoke_constexpr(_Fp&& __f, _A0&& __a0, _Args&& ...__args)
3465_LIBCPP_INVOKE_RETURN((_VSTD::forward<_A0>(__a0).*__f)(_VSTD::forward<_Args>(__args)...))
3466
3467template <class _Fp, class _A0, class ..._Args,
3468          class = __enable_if_bullet2<_Fp, _A0>>
3469inline _LIBCPP_INLINE_VISIBILITY
3470auto
3471__invoke(_Fp&& __f, _A0&& __a0, _Args&& ...__args)
3472_LIBCPP_INVOKE_RETURN((__a0.get().*__f)(_VSTD::forward<_Args>(__args)...))
3473
3474template <class _Fp, class _A0, class ..._Args,
3475          class = __enable_if_bullet2<_Fp, _A0>>
3476inline _LIBCPP_INLINE_VISIBILITY
3477_LIBCPP_CONSTEXPR auto
3478__invoke_constexpr(_Fp&& __f, _A0&& __a0, _Args&& ...__args)
3479_LIBCPP_INVOKE_RETURN((__a0.get().*__f)(_VSTD::forward<_Args>(__args)...))
3480
3481template <class _Fp, class _A0, class ..._Args,
3482          class = __enable_if_bullet3<_Fp, _A0>>
3483inline _LIBCPP_INLINE_VISIBILITY
3484auto
3485__invoke(_Fp&& __f, _A0&& __a0, _Args&& ...__args)
3486_LIBCPP_INVOKE_RETURN(((*_VSTD::forward<_A0>(__a0)).*__f)(_VSTD::forward<_Args>(__args)...))
3487
3488template <class _Fp, class _A0, class ..._Args,
3489          class = __enable_if_bullet3<_Fp, _A0>>
3490inline _LIBCPP_INLINE_VISIBILITY
3491_LIBCPP_CONSTEXPR auto
3492__invoke_constexpr(_Fp&& __f, _A0&& __a0, _Args&& ...__args)
3493_LIBCPP_INVOKE_RETURN(((*_VSTD::forward<_A0>(__a0)).*__f)(_VSTD::forward<_Args>(__args)...))
3494
3495// bullets 4, 5 and 6
3496
3497template <class _Fp, class _A0,
3498          class = __enable_if_bullet4<_Fp, _A0>>
3499inline _LIBCPP_INLINE_VISIBILITY
3500auto
3501__invoke(_Fp&& __f, _A0&& __a0)
3502_LIBCPP_INVOKE_RETURN(_VSTD::forward<_A0>(__a0).*__f)
3503
3504template <class _Fp, class _A0,
3505          class = __enable_if_bullet4<_Fp, _A0>>
3506inline _LIBCPP_INLINE_VISIBILITY
3507_LIBCPP_CONSTEXPR auto
3508__invoke_constexpr(_Fp&& __f, _A0&& __a0)
3509_LIBCPP_INVOKE_RETURN(_VSTD::forward<_A0>(__a0).*__f)
3510
3511template <class _Fp, class _A0,
3512          class = __enable_if_bullet5<_Fp, _A0>>
3513inline _LIBCPP_INLINE_VISIBILITY
3514auto
3515__invoke(_Fp&& __f, _A0&& __a0)
3516_LIBCPP_INVOKE_RETURN(__a0.get().*__f)
3517
3518template <class _Fp, class _A0,
3519          class = __enable_if_bullet5<_Fp, _A0>>
3520inline _LIBCPP_INLINE_VISIBILITY
3521_LIBCPP_CONSTEXPR auto
3522__invoke_constexpr(_Fp&& __f, _A0&& __a0)
3523_LIBCPP_INVOKE_RETURN(__a0.get().*__f)
3524
3525template <class _Fp, class _A0,
3526          class = __enable_if_bullet6<_Fp, _A0>>
3527inline _LIBCPP_INLINE_VISIBILITY
3528auto
3529__invoke(_Fp&& __f, _A0&& __a0)
3530_LIBCPP_INVOKE_RETURN((*_VSTD::forward<_A0>(__a0)).*__f)
3531
3532template <class _Fp, class _A0,
3533          class = __enable_if_bullet6<_Fp, _A0>>
3534inline _LIBCPP_INLINE_VISIBILITY
3535_LIBCPP_CONSTEXPR auto
3536__invoke_constexpr(_Fp&& __f, _A0&& __a0)
3537_LIBCPP_INVOKE_RETURN((*_VSTD::forward<_A0>(__a0)).*__f)
3538
3539// bullet 7
3540
3541template <class _Fp, class ..._Args>
3542inline _LIBCPP_INLINE_VISIBILITY
3543auto
3544__invoke(_Fp&& __f, _Args&& ...__args)
3545_LIBCPP_INVOKE_RETURN(_VSTD::forward<_Fp>(__f)(_VSTD::forward<_Args>(__args)...))
3546
3547template <class _Fp, class ..._Args>
3548inline _LIBCPP_INLINE_VISIBILITY
3549_LIBCPP_CONSTEXPR auto
3550__invoke_constexpr(_Fp&& __f, _Args&& ...__args)
3551_LIBCPP_INVOKE_RETURN(_VSTD::forward<_Fp>(__f)(_VSTD::forward<_Args>(__args)...))
3552
3553#undef _LIBCPP_INVOKE_RETURN
3554
3555// __invokable
3556template <class _Ret, class _Fp, class ..._Args>
3557struct __invokable_r
3558{
3559  template <class _XFp, class ..._XArgs>
3560  static auto __try_call(int) -> decltype(
3561    _VSTD::__invoke(_VSTD::declval<_XFp>(), _VSTD::declval<_XArgs>()...));
3562  template <class _XFp, class ..._XArgs>
3563  static __nat __try_call(...);
3564
3565  // FIXME: Check that _Ret, _Fp, and _Args... are all complete types, cv void,
3566  // or incomplete array types as required by the standard.
3567  using _Result = decltype(__try_call<_Fp, _Args...>(0));
3568
3569  using type =
3570  typename conditional<
3571      _IsNotSame<_Result, __nat>::value,
3572      typename conditional<
3573          is_void<_Ret>::value,
3574          true_type,
3575          is_convertible<_Result, _Ret>
3576      >::type,
3577      false_type
3578  >::type;
3579  static const bool value = type::value;
3580};
3581template <class _Fp, class ..._Args>
3582using __invokable = __invokable_r<void, _Fp, _Args...>;
3583
3584template <bool _IsInvokable, bool _IsCVVoid, class _Ret, class _Fp, class ..._Args>
3585struct __nothrow_invokable_r_imp {
3586  static const bool value = false;
3587};
3588
3589template <class _Ret, class _Fp, class ..._Args>
3590struct __nothrow_invokable_r_imp<true, false, _Ret, _Fp, _Args...>
3591{
3592    typedef __nothrow_invokable_r_imp _ThisT;
3593
3594    template <class _Tp>
3595    static void __test_noexcept(_Tp) noexcept;
3596
3597    static const bool value = noexcept(_ThisT::__test_noexcept<_Ret>(
3598        _VSTD::__invoke(_VSTD::declval<_Fp>(), _VSTD::declval<_Args>()...)));
3599};
3600
3601template <class _Ret, class _Fp, class ..._Args>
3602struct __nothrow_invokable_r_imp<true, true, _Ret, _Fp, _Args...>
3603{
3604    static const bool value = noexcept(
3605        _VSTD::__invoke(_VSTD::declval<_Fp>(), _VSTD::declval<_Args>()...));
3606};
3607
3608template <class _Ret, class _Fp, class ..._Args>
3609using __nothrow_invokable_r =
3610    __nothrow_invokable_r_imp<
3611            __invokable_r<_Ret, _Fp, _Args...>::value,
3612            is_void<_Ret>::value,
3613            _Ret, _Fp, _Args...
3614    >;
3615
3616template <class _Fp, class ..._Args>
3617using __nothrow_invokable =
3618    __nothrow_invokable_r_imp<
3619            __invokable<_Fp, _Args...>::value,
3620            true, void, _Fp, _Args...
3621    >;
3622
3623template <class _Fp, class ..._Args>
3624struct __invoke_of
3625    : public enable_if<
3626        __invokable<_Fp, _Args...>::value,
3627        typename __invokable_r<void, _Fp, _Args...>::_Result>
3628{
3629};
3630
3631// result_of
3632
3633template <class _Fp, class ..._Args>
3634class _LIBCPP_TEMPLATE_VIS result_of<_Fp(_Args...)>
3635    : public __invoke_of<_Fp, _Args...>
3636{
3637};
3638
3639#if _LIBCPP_STD_VER > 11
3640template <class _Tp> using result_of_t = typename result_of<_Tp>::type;
3641#endif
3642
3643#if _LIBCPP_STD_VER > 14
3644
3645// invoke_result
3646
3647template <class _Fn, class... _Args>
3648struct _LIBCPP_TEMPLATE_VIS invoke_result
3649    : __invoke_of<_Fn, _Args...>
3650{
3651};
3652
3653template <class _Fn, class... _Args>
3654using invoke_result_t = typename invoke_result<_Fn, _Args...>::type;
3655
3656// is_invocable
3657
3658template <class _Fn, class ..._Args>
3659struct _LIBCPP_TEMPLATE_VIS is_invocable
3660    : integral_constant<bool, __invokable<_Fn, _Args...>::value> {};
3661
3662template <class _Ret, class _Fn, class ..._Args>
3663struct _LIBCPP_TEMPLATE_VIS is_invocable_r
3664    : integral_constant<bool, __invokable_r<_Ret, _Fn, _Args...>::value> {};
3665
3666template <class _Fn, class ..._Args>
3667_LIBCPP_INLINE_VAR constexpr bool is_invocable_v
3668    = is_invocable<_Fn, _Args...>::value;
3669
3670template <class _Ret, class _Fn, class ..._Args>
3671_LIBCPP_INLINE_VAR constexpr bool is_invocable_r_v
3672    = is_invocable_r<_Ret, _Fn, _Args...>::value;
3673
3674// is_nothrow_invocable
3675
3676template <class _Fn, class ..._Args>
3677struct _LIBCPP_TEMPLATE_VIS is_nothrow_invocable
3678    : integral_constant<bool, __nothrow_invokable<_Fn, _Args...>::value> {};
3679
3680template <class _Ret, class _Fn, class ..._Args>
3681struct _LIBCPP_TEMPLATE_VIS is_nothrow_invocable_r
3682    : integral_constant<bool, __nothrow_invokable_r<_Ret, _Fn, _Args...>::value> {};
3683
3684template <class _Fn, class ..._Args>
3685_LIBCPP_INLINE_VAR constexpr bool is_nothrow_invocable_v
3686    = is_nothrow_invocable<_Fn, _Args...>::value;
3687
3688template <class _Ret, class _Fn, class ..._Args>
3689_LIBCPP_INLINE_VAR constexpr bool is_nothrow_invocable_r_v
3690    = is_nothrow_invocable_r<_Ret, _Fn, _Args...>::value;
3691
3692#endif // _LIBCPP_STD_VER > 14
3693
3694#endif  // !defined(_LIBCPP_CXX03_LANG)
3695
3696template <class _Tp> struct __is_swappable;
3697template <class _Tp> struct __is_nothrow_swappable;
3698
3699// swap, swap_ranges
3700
3701template <class _ForwardIterator1, class _ForwardIterator2>
3702inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
3703_ForwardIterator2
3704swap_ranges(_ForwardIterator1 __first1, _ForwardIterator1 __last1, _ForwardIterator2 __first2);
3705
3706template <class _Tp>
3707inline _LIBCPP_INLINE_VISIBILITY
3708#ifndef _LIBCPP_CXX03_LANG
3709typename enable_if
3710<
3711    is_move_constructible<_Tp>::value &&
3712    is_move_assignable<_Tp>::value
3713>::type
3714#else
3715void
3716#endif
3717_LIBCPP_CONSTEXPR_AFTER_CXX17
3718swap(_Tp& __x, _Tp& __y) _NOEXCEPT_(is_nothrow_move_constructible<_Tp>::value &&
3719                                    is_nothrow_move_assignable<_Tp>::value)
3720{
3721    _Tp __t(_VSTD::move(__x));
3722    __x = _VSTD::move(__y);
3723    __y = _VSTD::move(__t);
3724}
3725
3726template<class _Tp, size_t _Np>
3727inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
3728typename enable_if<
3729    __is_swappable<_Tp>::value
3730>::type
3731swap(_Tp (&__a)[_Np], _Tp (&__b)[_Np]) _NOEXCEPT_(__is_nothrow_swappable<_Tp>::value)
3732{
3733    _VSTD::swap_ranges(__a, __a + _Np, __b);
3734}
3735
3736template <class _ForwardIterator1, class _ForwardIterator2>
3737inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
3738_ForwardIterator2
3739swap_ranges(_ForwardIterator1 __first1, _ForwardIterator1 __last1, _ForwardIterator2 __first2)
3740{
3741    for(; __first1 != __last1; ++__first1, (void) ++__first2)
3742        swap(*__first1, *__first2);
3743    return __first2;
3744}
3745
3746// iter_swap
3747
3748template <class _ForwardIterator1, class _ForwardIterator2>
3749inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
3750void
3751iter_swap(_ForwardIterator1 __a, _ForwardIterator2 __b)
3752    //                                  _NOEXCEPT_(_NOEXCEPT_(swap(*__a, *__b)))
3753               _NOEXCEPT_(_NOEXCEPT_(swap(*_VSTD::declval<_ForwardIterator1>(),
3754                                          *_VSTD::declval<_ForwardIterator2>())))
3755{
3756    swap(*__a, *__b);
3757}
3758
3759// __swappable
3760
3761namespace __detail
3762{
3763// ALL generic swap overloads MUST already have a declaration available at this point.
3764
3765template <class _Tp, class _Up = _Tp,
3766          bool _NotVoid = !is_void<_Tp>::value && !is_void<_Up>::value>
3767struct __swappable_with
3768{
3769    template <class _LHS, class _RHS>
3770    static decltype(swap(_VSTD::declval<_LHS>(), _VSTD::declval<_RHS>()))
3771    __test_swap(int);
3772    template <class, class>
3773    static __nat __test_swap(long);
3774
3775    // Extra parens are needed for the C++03 definition of decltype.
3776    typedef decltype((__test_swap<_Tp, _Up>(0))) __swap1;
3777    typedef decltype((__test_swap<_Up, _Tp>(0))) __swap2;
3778
3779    static const bool value = _IsNotSame<__swap1, __nat>::value
3780                           && _IsNotSame<__swap2, __nat>::value;
3781};
3782
3783template <class _Tp, class _Up>
3784struct __swappable_with<_Tp, _Up,  false> : false_type {};
3785
3786template <class _Tp, class _Up = _Tp, bool _Swappable = __swappable_with<_Tp, _Up>::value>
3787struct __nothrow_swappable_with {
3788  static const bool value =
3789#ifndef _LIBCPP_HAS_NO_NOEXCEPT
3790      noexcept(swap(_VSTD::declval<_Tp>(), _VSTD::declval<_Up>()))
3791  &&  noexcept(swap(_VSTD::declval<_Up>(), _VSTD::declval<_Tp>()));
3792#else
3793      false;
3794#endif
3795};
3796
3797template <class _Tp, class _Up>
3798struct __nothrow_swappable_with<_Tp, _Up, false> : false_type {};
3799
3800}  // __detail
3801
3802template <class _Tp>
3803struct __is_swappable
3804    : public integral_constant<bool, __detail::__swappable_with<_Tp&>::value>
3805{
3806};
3807
3808template <class _Tp>
3809struct __is_nothrow_swappable
3810    : public integral_constant<bool, __detail::__nothrow_swappable_with<_Tp&>::value>
3811{
3812};
3813
3814#if _LIBCPP_STD_VER > 14
3815
3816template <class _Tp, class _Up>
3817struct _LIBCPP_TEMPLATE_VIS is_swappable_with
3818    : public integral_constant<bool, __detail::__swappable_with<_Tp, _Up>::value>
3819{
3820};
3821
3822template <class _Tp>
3823struct _LIBCPP_TEMPLATE_VIS is_swappable
3824    : public conditional<
3825        __is_referenceable<_Tp>::value,
3826        is_swappable_with<
3827            typename add_lvalue_reference<_Tp>::type,
3828            typename add_lvalue_reference<_Tp>::type>,
3829        false_type
3830    >::type
3831{
3832};
3833
3834template <class _Tp, class _Up>
3835struct _LIBCPP_TEMPLATE_VIS is_nothrow_swappable_with
3836    : public integral_constant<bool, __detail::__nothrow_swappable_with<_Tp, _Up>::value>
3837{
3838};
3839
3840template <class _Tp>
3841struct _LIBCPP_TEMPLATE_VIS is_nothrow_swappable
3842    : public conditional<
3843        __is_referenceable<_Tp>::value,
3844        is_nothrow_swappable_with<
3845            typename add_lvalue_reference<_Tp>::type,
3846            typename add_lvalue_reference<_Tp>::type>,
3847        false_type
3848    >::type
3849{
3850};
3851
3852template <class _Tp, class _Up>
3853_LIBCPP_INLINE_VAR constexpr bool is_swappable_with_v
3854    = is_swappable_with<_Tp, _Up>::value;
3855
3856template <class _Tp>
3857_LIBCPP_INLINE_VAR constexpr bool is_swappable_v
3858    = is_swappable<_Tp>::value;
3859
3860template <class _Tp, class _Up>
3861_LIBCPP_INLINE_VAR constexpr bool is_nothrow_swappable_with_v
3862    = is_nothrow_swappable_with<_Tp, _Up>::value;
3863
3864template <class _Tp>
3865_LIBCPP_INLINE_VAR constexpr bool is_nothrow_swappable_v
3866    = is_nothrow_swappable<_Tp>::value;
3867
3868#endif // _LIBCPP_STD_VER > 14
3869
3870template <class _Tp, bool = is_enum<_Tp>::value> struct __underlying_type_impl;
3871
3872template <class _Tp>
3873struct __underlying_type_impl<_Tp, false> {};
3874
3875template <class _Tp>
3876struct __underlying_type_impl<_Tp, true>
3877{
3878    typedef __underlying_type(_Tp) type;
3879};
3880
3881template <class _Tp>
3882struct underlying_type : __underlying_type_impl<_Tp, is_enum<_Tp>::value> {};
3883
3884#if _LIBCPP_STD_VER > 11
3885template <class _Tp> using underlying_type_t = typename underlying_type<_Tp>::type;
3886#endif
3887
3888
3889template <class _Tp, bool = is_enum<_Tp>::value>
3890struct __sfinae_underlying_type
3891{
3892    typedef typename underlying_type<_Tp>::type type;
3893    typedef decltype(((type)1) + 0) __promoted_type;
3894};
3895
3896template <class _Tp>
3897struct __sfinae_underlying_type<_Tp, false> {};
3898
3899inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
3900int __convert_to_integral(int __val) { return __val; }
3901
3902inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
3903unsigned __convert_to_integral(unsigned __val) { return __val; }
3904
3905inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
3906long __convert_to_integral(long __val) { return __val; }
3907
3908inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
3909unsigned long __convert_to_integral(unsigned long __val) { return __val; }
3910
3911inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
3912long long __convert_to_integral(long long __val) { return __val; }
3913
3914inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
3915unsigned long long __convert_to_integral(unsigned long long __val) {return __val; }
3916
3917template<typename _Fp>
3918inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
3919typename enable_if<is_floating_point<_Fp>::value, long long>::type
3920 __convert_to_integral(_Fp __val) { return __val; }
3921
3922#ifndef _LIBCPP_HAS_NO_INT128
3923inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
3924__int128_t __convert_to_integral(__int128_t __val) { return __val; }
3925
3926inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
3927__uint128_t __convert_to_integral(__uint128_t __val) { return __val; }
3928#endif
3929
3930template <class _Tp>
3931inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
3932typename __sfinae_underlying_type<_Tp>::__promoted_type
3933__convert_to_integral(_Tp __val) { return __val; }
3934
3935#ifndef _LIBCPP_CXX03_LANG
3936
3937template <class _Tp>
3938struct __has_operator_addressof_member_imp
3939{
3940    template <class _Up>
3941        static auto __test(int)
3942            -> typename __select_2nd<decltype(_VSTD::declval<_Up>().operator&()), true_type>::type;
3943    template <class>
3944        static auto __test(long) -> false_type;
3945
3946    static const bool value = decltype(__test<_Tp>(0))::value;
3947};
3948
3949template <class _Tp>
3950struct __has_operator_addressof_free_imp
3951{
3952    template <class _Up>
3953        static auto __test(int)
3954            -> typename __select_2nd<decltype(operator&(_VSTD::declval<_Up>())), true_type>::type;
3955    template <class>
3956        static auto __test(long) -> false_type;
3957
3958    static const bool value = decltype(__test<_Tp>(0))::value;
3959};
3960
3961template <class _Tp>
3962struct __has_operator_addressof
3963    : public integral_constant<bool, __has_operator_addressof_member_imp<_Tp>::value
3964                                  || __has_operator_addressof_free_imp<_Tp>::value>
3965{};
3966
3967#endif  // _LIBCPP_CXX03_LANG
3968
3969#if _LIBCPP_STD_VER > 14
3970
3971template <class...> using void_t = void;
3972
3973template <class... _Args>
3974struct conjunction : _And<_Args...> {};
3975template<class... _Args>
3976_LIBCPP_INLINE_VAR constexpr bool conjunction_v
3977    = conjunction<_Args...>::value;
3978
3979template <class... _Args>
3980struct disjunction : _Or<_Args...> {};
3981template<class... _Args>
3982_LIBCPP_INLINE_VAR constexpr bool disjunction_v
3983    = disjunction<_Args...>::value;
3984
3985template <class _Tp>
3986struct negation : _Not<_Tp> {};
3987template<class _Tp>
3988_LIBCPP_INLINE_VAR constexpr bool negation_v
3989    = negation<_Tp>::value;
3990#endif  // _LIBCPP_STD_VER > 14
3991
3992// These traits are used in __tree and __hash_table
3993#ifndef _LIBCPP_CXX03_LANG
3994struct __extract_key_fail_tag {};
3995struct __extract_key_self_tag {};
3996struct __extract_key_first_tag {};
3997
3998template <class _ValTy, class _Key,
3999          class _RawValTy = typename __unconstref<_ValTy>::type>
4000struct __can_extract_key
4001    : conditional<_IsSame<_RawValTy, _Key>::value, __extract_key_self_tag,
4002                  __extract_key_fail_tag>::type {};
4003
4004template <class _Pair, class _Key, class _First, class _Second>
4005struct __can_extract_key<_Pair, _Key, pair<_First, _Second>>
4006    : conditional<_IsSame<typename remove_const<_First>::type, _Key>::value,
4007                  __extract_key_first_tag, __extract_key_fail_tag>::type {};
4008
4009// __can_extract_map_key uses true_type/false_type instead of the tags.
4010// It returns true if _Key != _ContainerValueTy (the container is a map not a set)
4011// and _ValTy == _Key.
4012template <class _ValTy, class _Key, class _ContainerValueTy,
4013          class _RawValTy = typename __unconstref<_ValTy>::type>
4014struct __can_extract_map_key
4015    : integral_constant<bool, _IsSame<_RawValTy, _Key>::value> {};
4016
4017// This specialization returns __extract_key_fail_tag for non-map containers
4018// because _Key == _ContainerValueTy
4019template <class _ValTy, class _Key, class _RawValTy>
4020struct __can_extract_map_key<_ValTy, _Key, _Key, _RawValTy>
4021    : false_type {};
4022
4023#endif
4024
4025#ifndef _LIBCPP_HAS_NO_BUILTIN_IS_CONSTANT_EVALUATED
4026#if _LIBCPP_STD_VER > 17
4027_LIBCPP_INLINE_VISIBILITY
4028inline constexpr bool is_constant_evaluated() noexcept {
4029  return __builtin_is_constant_evaluated();
4030}
4031#endif
4032
4033inline _LIBCPP_CONSTEXPR
4034bool __libcpp_is_constant_evaluated() _NOEXCEPT { return __builtin_is_constant_evaluated(); }
4035#else
4036inline _LIBCPP_CONSTEXPR
4037bool __libcpp_is_constant_evaluated() _NOEXCEPT { return false; }
4038#endif
4039
4040template <class _CharT>
4041using _IsCharLikeType = _And<is_standard_layout<_CharT>, is_trivial<_CharT> >;
4042
4043_LIBCPP_END_NAMESPACE_STD
4044
4045#if _LIBCPP_STD_VER > 14
4046// std::byte
4047namespace std  // purposefully not versioned
4048{
4049template <class _Integer>
4050  constexpr typename enable_if<is_integral_v<_Integer>, byte>::type &
4051  operator<<=(byte& __lhs, _Integer __shift) noexcept
4052  { return __lhs = __lhs << __shift; }
4053
4054template <class _Integer>
4055  constexpr typename enable_if<is_integral_v<_Integer>, byte>::type
4056  operator<< (byte  __lhs, _Integer __shift) noexcept
4057  { return static_cast<byte>(static_cast<unsigned char>(static_cast<unsigned int>(__lhs) << __shift)); }
4058
4059template <class _Integer>
4060  constexpr typename enable_if<is_integral_v<_Integer>, byte>::type &
4061  operator>>=(byte& __lhs, _Integer __shift) noexcept
4062  { return __lhs = __lhs >> __shift; }
4063
4064template <class _Integer>
4065  constexpr typename enable_if<is_integral_v<_Integer>, byte>::type
4066  operator>> (byte  __lhs, _Integer __shift) noexcept
4067  { return static_cast<byte>(static_cast<unsigned char>(static_cast<unsigned int>(__lhs) >> __shift)); }
4068
4069template <class _Integer>
4070  constexpr typename enable_if<is_integral_v<_Integer>, _Integer>::type
4071  to_integer(byte __b) noexcept { return static_cast<_Integer>(__b); }
4072
4073}
4074#endif
4075
4076#endif  // _LIBCPP_TYPE_TRAITS
4077