1// -*- C++ -*-
2//===----------------------------------------------------------------------===//
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_scoped_enum; // C++2b
55    template <class T> struct is_scalar;
56    template <class T> struct is_object;
57    template <class T> struct is_compound;
58
59    // Const-volatile properties and transformations:
60    template <class T> struct is_const;
61    template <class T> struct is_volatile;
62    template <class T> struct remove_const;
63    template <class T> struct remove_volatile;
64    template <class T> struct remove_cv;
65    template <class T> struct add_const;
66    template <class T> struct add_volatile;
67    template <class T> struct add_cv;
68
69    // Reference transformations:
70    template <class T> struct remove_reference;
71    template <class T> struct add_lvalue_reference;
72    template <class T> struct add_rvalue_reference;
73
74    // Pointer transformations:
75    template <class T> struct remove_pointer;
76    template <class T> struct add_pointer;
77
78    template<class T> struct type_identity;                     // C++20
79    template<class T>
80      using type_identity_t = typename type_identity<T>::type;  // C++20
81
82    // Integral properties:
83    template <class T> struct is_signed;
84    template <class T> struct is_unsigned;
85    template <class T> struct make_signed;
86    template <class T> struct make_unsigned;
87
88    // Array properties and transformations:
89    template <class T> struct rank;
90    template <class T, unsigned I = 0> struct extent;
91    template <class T> struct remove_extent;
92    template <class T> struct remove_all_extents;
93
94    template <class T> struct is_bounded_array;                 // C++20
95    template <class T> struct is_unbounded_array;               // C++20
96
97    // Member introspection:
98    template <class T> struct is_pod;
99    template <class T> struct is_trivial;
100    template <class T> struct is_trivially_copyable;
101    template <class T> struct is_standard_layout;
102    template <class T> struct is_literal_type; // Deprecated in C++17; removed in C++20
103    template <class T> struct is_empty;
104    template <class T> struct is_polymorphic;
105    template <class T> struct is_abstract;
106    template <class T> struct is_final; // C++14
107    template <class T> struct is_aggregate; // C++17
108
109    template <class T, class... Args> struct is_constructible;
110    template <class T>                struct is_default_constructible;
111    template <class T>                struct is_copy_constructible;
112    template <class T>                struct is_move_constructible;
113    template <class T, class U>       struct is_assignable;
114    template <class T>                struct is_copy_assignable;
115    template <class T>                struct is_move_assignable;
116    template <class T, class U>       struct is_swappable_with;       // C++17
117    template <class T>                struct is_swappable;            // C++17
118    template <class T>                struct is_destructible;
119
120    template <class T, class... Args> struct is_trivially_constructible;
121    template <class T>                struct is_trivially_default_constructible;
122    template <class T>                struct is_trivially_copy_constructible;
123    template <class T>                struct is_trivially_move_constructible;
124    template <class T, class U>       struct is_trivially_assignable;
125    template <class T>                struct is_trivially_copy_assignable;
126    template <class T>                struct is_trivially_move_assignable;
127    template <class T>                struct is_trivially_destructible;
128
129    template <class T, class... Args> struct is_nothrow_constructible;
130    template <class T>                struct is_nothrow_default_constructible;
131    template <class T>                struct is_nothrow_copy_constructible;
132    template <class T>                struct is_nothrow_move_constructible;
133    template <class T, class U>       struct is_nothrow_assignable;
134    template <class T>                struct is_nothrow_copy_assignable;
135    template <class T>                struct is_nothrow_move_assignable;
136    template <class T, class U>       struct is_nothrow_swappable_with; // C++17
137    template <class T>                struct is_nothrow_swappable;      // C++17
138    template <class T>                struct is_nothrow_destructible;
139
140    template <class T> struct has_virtual_destructor;
141
142    template<class T> struct has_unique_object_representations;         // C++17
143
144    // Relationships between types:
145    template <class T, class U> struct is_same;
146    template <class Base, class Derived> struct is_base_of;
147
148    template <class From, class To> struct is_convertible;
149    template <typename From, typename To> struct is_nothrow_convertible;                  // C++20
150    template <typename From, typename To> inline constexpr bool is_nothrow_convertible_v; // C++20
151
152    template <class Fn, class... ArgTypes> struct is_invocable;
153    template <class R, class Fn, class... ArgTypes> struct is_invocable_r;
154
155    template <class Fn, class... ArgTypes> struct is_nothrow_invocable;
156    template <class R, class Fn, class... ArgTypes> struct is_nothrow_invocable_r;
157
158    // Alignment properties and transformations:
159    template <class T> struct alignment_of;
160    template <size_t Len, size_t Align = most_stringent_alignment_requirement>
161        struct aligned_storage;
162    template <size_t Len, class... Types> struct aligned_union;
163    template <class T> struct remove_cvref; // C++20
164
165    template <class T> struct decay;
166    template <class... T> struct common_type;
167    template <class T> struct underlying_type;
168    template <class> class result_of; // undefined; deprecated in C++17; removed in C++20
169    template <class Fn, class... ArgTypes> class result_of<Fn(ArgTypes...)>; // deprecated in C++17; removed in C++20
170    template <class Fn, class... ArgTypes> struct invoke_result;  // C++17
171
172    // const-volatile modifications:
173    template <class T>
174      using remove_const_t    = typename remove_const<T>::type;  // C++14
175    template <class T>
176      using remove_volatile_t = typename remove_volatile<T>::type;  // C++14
177    template <class T>
178      using remove_cv_t       = typename remove_cv<T>::type;  // C++14
179    template <class T>
180      using add_const_t       = typename add_const<T>::type;  // C++14
181    template <class T>
182      using add_volatile_t    = typename add_volatile<T>::type;  // C++14
183    template <class T>
184      using add_cv_t          = typename add_cv<T>::type;  // C++14
185
186    // reference modifications:
187    template <class T>
188      using remove_reference_t     = typename remove_reference<T>::type;  // C++14
189    template <class T>
190      using add_lvalue_reference_t = typename add_lvalue_reference<T>::type;  // C++14
191    template <class T>
192      using add_rvalue_reference_t = typename add_rvalue_reference<T>::type;  // C++14
193
194    // sign modifications:
195    template <class T>
196      using make_signed_t   = typename make_signed<T>::type;  // C++14
197    template <class T>
198      using make_unsigned_t = typename make_unsigned<T>::type;  // C++14
199
200    // array modifications:
201    template <class T>
202      using remove_extent_t      = typename remove_extent<T>::type;  // C++14
203    template <class T>
204      using remove_all_extents_t = typename remove_all_extents<T>::type;  // C++14
205
206    template <class T>
207      inline constexpr bool is_bounded_array_v
208        = is_bounded_array<T>::value;                                     // C++20
209      inline constexpr bool is_unbounded_array_v
210        = is_unbounded_array<T>::value;                                   // C++20
211
212    // pointer modifications:
213    template <class T>
214      using remove_pointer_t = typename remove_pointer<T>::type;  // C++14
215    template <class T>
216      using add_pointer_t    = typename add_pointer<T>::type;  // C++14
217
218    // other transformations:
219    template <size_t Len, size_t Align=default-alignment>
220      using aligned_storage_t = typename aligned_storage<Len,Align>::type;  // C++14
221    template <size_t Len, class... Types>
222      using aligned_union_t   = typename aligned_union<Len,Types...>::type;  // C++14
223    template <class T>
224      using remove_cvref_t    = typename remove_cvref<T>::type;  // C++20
225    template <class T>
226      using decay_t           = typename decay<T>::type;  // C++14
227    template <bool b, class T=void>
228      using enable_if_t       = typename enable_if<b,T>::type;  // C++14
229    template <bool b, class T, class F>
230      using conditional_t     = typename conditional<b,T,F>::type;  // C++14
231    template <class... T>
232      using common_type_t     = typename common_type<T...>::type;  // C++14
233    template <class T>
234      using underlying_type_t = typename underlying_type<T>::type;  // C++14
235    template <class T>
236      using result_of_t       = typename result_of<T>::type;  // C++14; deprecated in C++17; removed in C++20
237    template <class Fn, class... ArgTypes>
238      using invoke_result_t   = typename invoke_result<Fn, ArgTypes...>::type;  // C++17
239
240    template <class...>
241      using void_t = void;   // C++17
242
243      // See C++14 20.10.4.1, primary type categories
244      template <class T> inline constexpr bool is_void_v
245        = is_void<T>::value;                                             // C++17
246      template <class T> inline constexpr bool is_null_pointer_v
247        = is_null_pointer<T>::value;                                     // C++17
248      template <class T> inline constexpr bool is_integral_v
249        = is_integral<T>::value;                                         // C++17
250      template <class T> inline constexpr bool is_floating_point_v
251        = is_floating_point<T>::value;                                   // C++17
252      template <class T> inline constexpr bool is_array_v
253        = is_array<T>::value;                                            // C++17
254      template <class T> inline constexpr bool is_pointer_v
255        = is_pointer<T>::value;                                          // C++17
256      template <class T> inline constexpr bool is_lvalue_reference_v
257        = is_lvalue_reference<T>::value;                                 // C++17
258      template <class T> inline constexpr bool is_rvalue_reference_v
259        = is_rvalue_reference<T>::value;                                 // C++17
260      template <class T> inline constexpr bool is_member_object_pointer_v
261        = is_member_object_pointer<T>::value;                            // C++17
262      template <class T> inline constexpr bool is_member_function_pointer_v
263        = is_member_function_pointer<T>::value;                          // C++17
264      template <class T> inline constexpr bool is_enum_v
265        = is_enum<T>::value;                                             // C++17
266      template <class T> inline constexpr bool is_union_v
267        = is_union<T>::value;                                            // C++17
268      template <class T> inline constexpr bool is_class_v
269        = is_class<T>::value;                                            // C++17
270      template <class T> inline constexpr bool is_function_v
271        = is_function<T>::value;                                         // C++17
272
273      // See C++14 20.10.4.2, composite type categories
274      template <class T> inline constexpr bool is_reference_v
275        = is_reference<T>::value;                                        // C++17
276      template <class T> inline constexpr bool is_arithmetic_v
277        = is_arithmetic<T>::value;                                       // C++17
278      template <class T> inline constexpr bool is_fundamental_v
279        = is_fundamental<T>::value;                                      // C++17
280      template <class T> inline constexpr bool is_object_v
281        = is_object<T>::value;                                           // C++17
282      template <class T> inline constexpr bool is_scalar_v
283        = is_scalar<T>::value;                                           // C++17
284      template <class T> inline constexpr bool is_compound_v
285        = is_compound<T>::value;                                         // C++17
286      template <class T> inline constexpr bool is_member_pointer_v
287        = is_member_pointer<T>::value;                                   // C++17
288      template <class T> inline constexpr bool is_scoped_enum_v
289        = is_scoped_enum<T>::value;                                      // C++2b
290
291      // See C++14 20.10.4.3, type properties
292      template <class T> inline constexpr bool is_const_v
293        = is_const<T>::value;                                            // C++17
294      template <class T> inline constexpr bool is_volatile_v
295        = is_volatile<T>::value;                                         // C++17
296      template <class T> inline constexpr bool is_trivial_v
297        = is_trivial<T>::value;                                          // C++17
298      template <class T> inline constexpr bool is_trivially_copyable_v
299        = is_trivially_copyable<T>::value;                               // C++17
300      template <class T> inline constexpr bool is_standard_layout_v
301        = is_standard_layout<T>::value;                                  // C++17
302      template <class T> inline constexpr bool is_pod_v
303        = is_pod<T>::value;                                              // C++17
304      template <class T> inline constexpr bool is_literal_type_v
305        = is_literal_type<T>::value;                                     // C++17; deprecated in C++17; removed in C++20
306      template <class T> inline constexpr bool is_empty_v
307        = is_empty<T>::value;                                            // C++17
308      template <class T> inline constexpr bool is_polymorphic_v
309        = is_polymorphic<T>::value;                                      // C++17
310      template <class T> inline constexpr bool is_abstract_v
311        = is_abstract<T>::value;                                         // C++17
312      template <class T> inline constexpr bool is_final_v
313        = is_final<T>::value;                                            // C++17
314      template <class T> inline constexpr bool is_aggregate_v
315        = is_aggregate<T>::value;                                        // C++17
316      template <class T> inline constexpr bool is_signed_v
317        = is_signed<T>::value;                                           // C++17
318      template <class T> inline constexpr bool is_unsigned_v
319        = is_unsigned<T>::value;                                         // C++17
320      template <class T, class... Args> inline constexpr bool is_constructible_v
321        = is_constructible<T, Args...>::value;                           // C++17
322      template <class T> inline constexpr bool is_default_constructible_v
323        = is_default_constructible<T>::value;                            // C++17
324      template <class T> inline constexpr bool is_copy_constructible_v
325        = is_copy_constructible<T>::value;                               // C++17
326      template <class T> inline constexpr bool is_move_constructible_v
327        = is_move_constructible<T>::value;                               // C++17
328      template <class T, class U> inline constexpr bool is_assignable_v
329        = is_assignable<T, U>::value;                                    // C++17
330      template <class T> inline constexpr bool is_copy_assignable_v
331        = is_copy_assignable<T>::value;                                  // C++17
332      template <class T> inline constexpr bool is_move_assignable_v
333        = is_move_assignable<T>::value;                                  // C++17
334      template <class T, class U> inline constexpr bool is_swappable_with_v
335        = is_swappable_with<T, U>::value;                                // C++17
336      template <class T> inline constexpr bool is_swappable_v
337        = is_swappable<T>::value;                                        // C++17
338      template <class T> inline constexpr bool is_destructible_v
339        = is_destructible<T>::value;                                     // C++17
340      template <class T, class... Args> inline constexpr bool is_trivially_constructible_v
341        = is_trivially_constructible<T, Args...>::value;                 // C++17
342      template <class T> inline constexpr bool is_trivially_default_constructible_v
343        = is_trivially_default_constructible<T>::value;                  // C++17
344      template <class T> inline constexpr bool is_trivially_copy_constructible_v
345        = is_trivially_copy_constructible<T>::value;                     // C++17
346      template <class T> inline constexpr bool is_trivially_move_constructible_v
347        = is_trivially_move_constructible<T>::value;                     // C++17
348      template <class T, class U> inline constexpr bool is_trivially_assignable_v
349        = is_trivially_assignable<T, U>::value;                          // C++17
350      template <class T> inline constexpr bool is_trivially_copy_assignable_v
351        = is_trivially_copy_assignable<T>::value;                        // C++17
352      template <class T> inline constexpr bool is_trivially_move_assignable_v
353        = is_trivially_move_assignable<T>::value;                        // C++17
354      template <class T> inline constexpr bool is_trivially_destructible_v
355        = is_trivially_destructible<T>::value;                           // C++17
356      template <class T, class... Args> inline constexpr bool is_nothrow_constructible_v
357        = is_nothrow_constructible<T, Args...>::value;                   // C++17
358      template <class T> inline constexpr bool is_nothrow_default_constructible_v
359        = is_nothrow_default_constructible<T>::value;                    // C++17
360      template <class T> inline constexpr bool is_nothrow_copy_constructible_v
361        = is_nothrow_copy_constructible<T>::value;                       // C++17
362      template <class T> inline constexpr bool is_nothrow_move_constructible_v
363        = is_nothrow_move_constructible<T>::value;                       // C++17
364      template <class T, class U> inline constexpr bool is_nothrow_assignable_v
365        = is_nothrow_assignable<T, U>::value;                            // C++17
366      template <class T> inline constexpr bool is_nothrow_copy_assignable_v
367        = is_nothrow_copy_assignable<T>::value;                          // C++17
368      template <class T> inline constexpr bool is_nothrow_move_assignable_v
369        = is_nothrow_move_assignable<T>::value;                          // C++17
370      template <class T, class U> inline constexpr bool is_nothrow_swappable_with_v
371        = is_nothrow_swappable_with<T, U>::value;                       // C++17
372      template <class T> inline constexpr bool is_nothrow_swappable_v
373        = is_nothrow_swappable<T>::value;                               // C++17
374      template <class T> inline constexpr bool is_nothrow_destructible_v
375        = is_nothrow_destructible<T>::value;                             // C++17
376      template <class T> inline constexpr bool has_virtual_destructor_v
377        = has_virtual_destructor<T>::value;                              // C++17
378      template<class T> inline constexpr bool has_unique_object_representations_v // C++17
379        = has_unique_object_representations<T>::value;
380
381      // See C++14 20.10.5, type property queries
382      template <class T> inline constexpr size_t alignment_of_v
383        = alignment_of<T>::value;                                        // C++17
384      template <class T> inline constexpr size_t rank_v
385        = rank<T>::value;                                                // C++17
386      template <class T, unsigned I = 0> inline constexpr size_t extent_v
387        = extent<T, I>::value;                                           // C++17
388
389      // See C++14 20.10.6, type relations
390      template <class T, class U> inline constexpr bool is_same_v
391        = is_same<T, U>::value;                                          // C++17
392      template <class Base, class Derived> inline constexpr bool is_base_of_v
393        = is_base_of<Base, Derived>::value;                              // C++17
394      template <class From, class To> inline constexpr bool is_convertible_v
395        = is_convertible<From, To>::value;                               // C++17
396      template <class Fn, class... ArgTypes> inline constexpr bool is_invocable_v
397        = is_invocable<Fn, ArgTypes...>::value;                          // C++17
398      template <class R, class Fn, class... ArgTypes> inline constexpr bool is_invocable_r_v
399        = is_invocable_r<R, Fn, ArgTypes...>::value;                     // C++17
400      template <class Fn, class... ArgTypes> inline constexpr bool is_nothrow_invocable_v
401        = is_nothrow_invocable<Fn, ArgTypes...>::value;                  // C++17
402      template <class R, class Fn, class... ArgTypes> inline constexpr bool is_nothrow_invocable_r_v
403        = is_nothrow_invocable_r<R, Fn, ArgTypes...>::value;             // C++17
404
405      // [meta.logical], logical operator traits:
406      template<class... B> struct conjunction;                           // C++17
407      template<class... B>
408        inline constexpr bool conjunction_v = conjunction<B...>::value;  // C++17
409      template<class... B> struct disjunction;                           // C++17
410      template<class... B>
411        inline constexpr bool disjunction_v = disjunction<B...>::value;  // C++17
412      template<class B> struct negation;                                 // C++17
413      template<class B>
414        inline constexpr bool negation_v = negation<B>::value;           // C++17
415
416}
417
418*/
419
420#include <__assert> // all public C++ headers provide the assertion handler
421#include <__config>
422#include <cstddef>
423#include <version>
424
425#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
426#  pragma GCC system_header
427#endif
428
429_LIBCPP_BEGIN_NAMESPACE_STD
430
431template <class _T1, class _T2> struct _LIBCPP_TEMPLATE_VIS pair;
432template <class _Tp> class _LIBCPP_TEMPLATE_VIS reference_wrapper;
433template <class _Tp> struct _LIBCPP_TEMPLATE_VIS hash;
434
435template <class _Tp, _Tp __v>
436struct _LIBCPP_TEMPLATE_VIS integral_constant
437{
438  static _LIBCPP_CONSTEXPR const _Tp      value = __v;
439  typedef _Tp               value_type;
440  typedef integral_constant type;
441  _LIBCPP_INLINE_VISIBILITY
442  _LIBCPP_CONSTEXPR operator value_type() const _NOEXCEPT {return value;}
443#if _LIBCPP_STD_VER > 11
444  _LIBCPP_INLINE_VISIBILITY
445  constexpr value_type operator ()() const _NOEXCEPT {return value;}
446#endif
447};
448
449template <class _Tp, _Tp __v>
450_LIBCPP_CONSTEXPR const _Tp integral_constant<_Tp, __v>::value;
451
452#if _LIBCPP_STD_VER > 14
453template <bool __b>
454using bool_constant = integral_constant<bool, __b>;
455#endif
456
457template <bool, class _Tp = void> struct _LIBCPP_TEMPLATE_VIS enable_if {};
458template <class _Tp> struct _LIBCPP_TEMPLATE_VIS enable_if<true, _Tp> {typedef _Tp type;};
459
460template <bool _Bp, class _Tp = void> using __enable_if_t _LIBCPP_NODEBUG = typename enable_if<_Bp, _Tp>::type;
461
462#if _LIBCPP_STD_VER > 11
463template <bool _Bp, class _Tp = void> using enable_if_t = typename enable_if<_Bp, _Tp>::type;
464#endif
465
466typedef integral_constant<bool, true>  true_type;
467typedef integral_constant<bool, false> false_type;
468
469template <bool _Val>
470using _BoolConstant _LIBCPP_NODEBUG = integral_constant<bool, _Val>;
471
472template <bool> struct _MetaBase;
473template <>
474struct _MetaBase<true> {
475  template <class _Tp, class _Up>
476  using _SelectImpl _LIBCPP_NODEBUG = _Tp;
477  template <template <class...> class _FirstFn, template <class...> class, class ..._Args>
478  using _SelectApplyImpl _LIBCPP_NODEBUG = _FirstFn<_Args...>;
479  template <class _First, class...>
480  using _FirstImpl _LIBCPP_NODEBUG = _First;
481  template <class, class _Second, class...>
482  using _SecondImpl _LIBCPP_NODEBUG = _Second;
483  template <class _Result, class _First, class ..._Rest>
484  using _OrImpl _LIBCPP_NODEBUG = typename _MetaBase<_First::value != true && sizeof...(_Rest) != 0>::template _OrImpl<_First, _Rest...>;
485};
486
487template <>
488struct _MetaBase<false> {
489  template <class _Tp, class _Up>
490  using _SelectImpl _LIBCPP_NODEBUG = _Up;
491  template <template <class...> class, template <class...> class _SecondFn, class ..._Args>
492  using _SelectApplyImpl _LIBCPP_NODEBUG = _SecondFn<_Args...>;
493  template <class _Result, class ...>
494  using _OrImpl _LIBCPP_NODEBUG = _Result;
495};
496template <bool _Cond, class _IfRes, class _ElseRes>
497using _If _LIBCPP_NODEBUG = typename _MetaBase<_Cond>::template _SelectImpl<_IfRes, _ElseRes>;
498template <class ..._Rest>
499using _Or _LIBCPP_NODEBUG = typename _MetaBase< sizeof...(_Rest) != 0 >::template _OrImpl<false_type, _Rest...>;
500template <class _Pred>
501struct _Not : _BoolConstant<!_Pred::value> {};
502template <class ..._Args>
503using _FirstType _LIBCPP_NODEBUG = typename _MetaBase<(sizeof...(_Args) >= 1)>::template _FirstImpl<_Args...>;
504template <class ..._Args>
505using _SecondType _LIBCPP_NODEBUG = typename _MetaBase<(sizeof...(_Args) >= 2)>::template _SecondImpl<_Args...>;
506
507template <class ...> using __expand_to_true = true_type;
508template <class ..._Pred>
509__expand_to_true<__enable_if_t<_Pred::value>...> __and_helper(int);
510template <class ...>
511false_type __and_helper(...);
512template <class ..._Pred>
513using _And _LIBCPP_NODEBUG = decltype(__and_helper<_Pred...>(0));
514
515template <template <class...> class _Func, class ..._Args>
516struct _Lazy : _Func<_Args...> {};
517
518// Member detector base
519
520template <template <class...> class _Templ, class ..._Args, class = _Templ<_Args...> >
521true_type __sfinae_test_impl(int);
522template <template <class...> class, class ...>
523false_type __sfinae_test_impl(...);
524
525template <template <class ...> class _Templ, class ..._Args>
526using _IsValidExpansion _LIBCPP_NODEBUG = decltype(__sfinae_test_impl<_Templ, _Args...>(0));
527
528template <class>
529struct __void_t { typedef void type; };
530
531template <class _Tp, bool>
532struct _LIBCPP_TEMPLATE_VIS __dependent_type : public _Tp {};
533
534
535template <bool _Bp, class _If, class _Then>
536    struct _LIBCPP_TEMPLATE_VIS conditional {typedef _If type;};
537template <class _If, class _Then>
538    struct _LIBCPP_TEMPLATE_VIS conditional<false, _If, _Then> {typedef _Then type;};
539
540#if _LIBCPP_STD_VER > 11
541template <bool _Bp, class _If, class _Then> using conditional_t = typename conditional<_Bp, _If, _Then>::type;
542#endif
543
544// is_same
545
546template <class _Tp, class _Up>
547struct _LIBCPP_TEMPLATE_VIS is_same : _BoolConstant<__is_same(_Tp, _Up)> { };
548
549#if _LIBCPP_STD_VER > 14
550template <class _Tp, class _Up>
551inline constexpr bool is_same_v = __is_same(_Tp, _Up);
552#endif
553
554// _IsSame<T,U> has the same effect as is_same<T,U> but instantiates fewer types:
555// is_same<A,B> and is_same<C,D> are guaranteed to be different types, but
556// _IsSame<A,B> and _IsSame<C,D> are the same type (namely, false_type).
557// Neither GCC nor Clang can mangle the __is_same builtin, so _IsSame
558// mustn't be directly used anywhere that contributes to name-mangling
559// (such as in a dependent return type).
560
561template <class _Tp, class _Up>
562using _IsSame = _BoolConstant<__is_same(_Tp, _Up)>;
563
564template <class _Tp, class _Up>
565using _IsNotSame = _BoolConstant<!__is_same(_Tp, _Up)>;
566
567template <class _Tp>
568using __test_for_primary_template = __enable_if_t<
569    _IsSame<_Tp, typename _Tp::__primary_template>::value
570  >;
571template <class _Tp>
572using __is_primary_template = _IsValidExpansion<
573    __test_for_primary_template, _Tp
574  >;
575
576// helper class
577
578struct __two {char __lx[2];};
579
580// is_const
581
582#if __has_keyword(__is_const)
583
584template <class _Tp>
585struct _LIBCPP_TEMPLATE_VIS is_const : _BoolConstant<__is_const(_Tp)> { };
586
587#if _LIBCPP_STD_VER > 14
588template <class _Tp>
589inline constexpr bool is_const_v = __is_const(_Tp);
590#endif
591
592#else
593
594template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_const            : public false_type {};
595template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_const<_Tp const> : public true_type {};
596
597#if _LIBCPP_STD_VER > 14
598template <class _Tp>
599inline constexpr bool is_const_v = is_const<_Tp>::value;
600#endif
601
602#endif // __has_keyword(__is_const)
603
604// is_volatile
605
606#if __has_keyword(__is_volatile)
607
608template <class _Tp>
609struct _LIBCPP_TEMPLATE_VIS is_volatile : _BoolConstant<__is_volatile(_Tp)> { };
610
611#if _LIBCPP_STD_VER > 14
612template <class _Tp>
613inline constexpr bool is_volatile_v = __is_volatile(_Tp);
614#endif
615
616#else
617
618template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_volatile               : public false_type {};
619template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_volatile<_Tp volatile> : public true_type {};
620
621#if _LIBCPP_STD_VER > 14
622template <class _Tp>
623inline constexpr bool is_volatile_v = is_volatile<_Tp>::value;
624#endif
625
626#endif // __has_keyword(__is_volatile)
627
628// remove_const
629
630template <class _Tp> struct _LIBCPP_TEMPLATE_VIS remove_const            {typedef _Tp type;};
631template <class _Tp> struct _LIBCPP_TEMPLATE_VIS remove_const<const _Tp> {typedef _Tp type;};
632#if _LIBCPP_STD_VER > 11
633template <class _Tp> using remove_const_t = typename remove_const<_Tp>::type;
634#endif
635
636// remove_volatile
637
638template <class _Tp> struct _LIBCPP_TEMPLATE_VIS remove_volatile               {typedef _Tp type;};
639template <class _Tp> struct _LIBCPP_TEMPLATE_VIS remove_volatile<volatile _Tp> {typedef _Tp type;};
640#if _LIBCPP_STD_VER > 11
641template <class _Tp> using remove_volatile_t = typename remove_volatile<_Tp>::type;
642#endif
643
644// remove_cv
645
646template <class _Tp> struct _LIBCPP_TEMPLATE_VIS remove_cv
647{typedef typename remove_volatile<typename remove_const<_Tp>::type>::type type;};
648#if _LIBCPP_STD_VER > 11
649template <class _Tp> using remove_cv_t = typename remove_cv<_Tp>::type;
650#endif
651
652// is_void
653
654#if __has_keyword(__is_void)
655
656template <class _Tp>
657struct _LIBCPP_TEMPLATE_VIS is_void : _BoolConstant<__is_void(_Tp)> { };
658
659#if _LIBCPP_STD_VER > 14
660template <class _Tp>
661inline constexpr bool is_void_v = __is_void(_Tp);
662#endif
663
664#else
665
666template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_void
667    : public is_same<typename remove_cv<_Tp>::type, void> {};
668
669#if _LIBCPP_STD_VER > 14
670template <class _Tp>
671inline constexpr bool is_void_v = is_void<_Tp>::value;
672#endif
673
674#endif // __has_keyword(__is_void)
675
676// __is_nullptr_t
677
678template <class _Tp> struct __is_nullptr_t_impl       : public false_type {};
679template <>          struct __is_nullptr_t_impl<nullptr_t> : public true_type {};
680
681template <class _Tp> struct _LIBCPP_TEMPLATE_VIS __is_nullptr_t
682    : public __is_nullptr_t_impl<typename remove_cv<_Tp>::type> {};
683
684#if _LIBCPP_STD_VER > 11
685template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_null_pointer
686    : public __is_nullptr_t_impl<typename remove_cv<_Tp>::type> {};
687
688#if _LIBCPP_STD_VER > 14
689template <class _Tp>
690inline constexpr bool is_null_pointer_v = is_null_pointer<_Tp>::value;
691#endif
692#endif // _LIBCPP_STD_VER > 11
693
694// is_integral
695
696#if __has_keyword(__is_integral)
697
698template <class _Tp>
699struct _LIBCPP_TEMPLATE_VIS is_integral : _BoolConstant<__is_integral(_Tp)> { };
700
701#if _LIBCPP_STD_VER > 14
702template <class _Tp>
703inline constexpr bool is_integral_v = __is_integral(_Tp);
704#endif
705
706#else
707
708template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_integral
709    : public _BoolConstant<__libcpp_is_integral<typename remove_cv<_Tp>::type>::value> {};
710
711#if _LIBCPP_STD_VER > 14
712template <class _Tp>
713inline constexpr bool is_integral_v = is_integral<_Tp>::value;
714#endif
715
716#endif // __has_keyword(__is_integral)
717
718// [basic.fundamental] defines five standard signed integer types;
719// __int128_t is an extended signed integer type.
720// The signed and unsigned integer types, plus bool and the
721// five types with "char" in their name, compose the "integral" types.
722
723template <class _Tp> struct __libcpp_is_signed_integer : public false_type {};
724template <> struct __libcpp_is_signed_integer<signed char>      : public true_type {};
725template <> struct __libcpp_is_signed_integer<signed short>     : public true_type {};
726template <> struct __libcpp_is_signed_integer<signed int>       : public true_type {};
727template <> struct __libcpp_is_signed_integer<signed long>      : public true_type {};
728template <> struct __libcpp_is_signed_integer<signed long long> : public true_type {};
729#ifndef _LIBCPP_HAS_NO_INT128
730template <> struct __libcpp_is_signed_integer<__int128_t>       : public true_type {};
731#endif
732
733template <class _Tp> struct __libcpp_is_unsigned_integer : public false_type {};
734template <> struct __libcpp_is_unsigned_integer<unsigned char>      : public true_type {};
735template <> struct __libcpp_is_unsigned_integer<unsigned short>     : public true_type {};
736template <> struct __libcpp_is_unsigned_integer<unsigned int>       : public true_type {};
737template <> struct __libcpp_is_unsigned_integer<unsigned long>      : public true_type {};
738template <> struct __libcpp_is_unsigned_integer<unsigned long long> : public true_type {};
739#ifndef _LIBCPP_HAS_NO_INT128
740template <> struct __libcpp_is_unsigned_integer<__uint128_t>        : public true_type {};
741#endif
742
743// is_floating_point
744// <concepts> implements __libcpp_floating_point
745
746template <class _Tp> struct __libcpp_is_floating_point              : public false_type {};
747template <>          struct __libcpp_is_floating_point<float>       : public true_type {};
748template <>          struct __libcpp_is_floating_point<double>      : public true_type {};
749template <>          struct __libcpp_is_floating_point<long double> : public true_type {};
750
751template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_floating_point
752    : public __libcpp_is_floating_point<typename remove_cv<_Tp>::type> {};
753
754#if _LIBCPP_STD_VER > 14
755template <class _Tp>
756inline constexpr bool is_floating_point_v = is_floating_point<_Tp>::value;
757#endif
758
759// is_array
760
761// TODO: Clang incorrectly reports that __is_array is true for T[0].
762//       Re-enable the branch once https://llvm.org/PR54705 is fixed.
763#if __has_keyword(__is_array) && 0
764
765template <class _Tp>
766struct _LIBCPP_TEMPLATE_VIS is_array : _BoolConstant<__is_array(_Tp)> { };
767
768#if _LIBCPP_STD_VER > 14
769template <class _Tp>
770inline constexpr bool is_array_v = __is_array(_Tp);
771#endif
772
773#else
774
775template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_array
776    : public false_type {};
777template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_array<_Tp[]>
778    : public true_type {};
779template <class _Tp, size_t _Np> struct _LIBCPP_TEMPLATE_VIS is_array<_Tp[_Np]>
780    : public true_type {};
781
782#if _LIBCPP_STD_VER > 14
783template <class _Tp>
784inline constexpr bool is_array_v = is_array<_Tp>::value;
785#endif
786
787#endif // __has_keyword(__is_array)
788
789// is_pointer
790
791// Before AppleClang 12.0.5, __is_pointer didn't work for Objective-C types.
792#if __has_keyword(__is_pointer) &&                                             \
793    !(defined(_LIBCPP_APPLE_CLANG_VER) && _LIBCPP_APPLE_CLANG_VER < 1205)
794
795template<class _Tp>
796struct _LIBCPP_TEMPLATE_VIS is_pointer : _BoolConstant<__is_pointer(_Tp)> { };
797
798#if _LIBCPP_STD_VER > 14
799template <class _Tp>
800inline constexpr bool is_pointer_v = __is_pointer(_Tp);
801#endif
802
803#else // __has_keyword(__is_pointer)
804
805template <class _Tp> struct __libcpp_is_pointer       : public false_type {};
806template <class _Tp> struct __libcpp_is_pointer<_Tp*> : public true_type {};
807
808template <class _Tp> struct __libcpp_remove_objc_qualifiers { typedef _Tp type; };
809#if defined(_LIBCPP_HAS_OBJC_ARC)
810template <class _Tp> struct __libcpp_remove_objc_qualifiers<_Tp __strong> { typedef _Tp type; };
811template <class _Tp> struct __libcpp_remove_objc_qualifiers<_Tp __weak> { typedef _Tp type; };
812template <class _Tp> struct __libcpp_remove_objc_qualifiers<_Tp __autoreleasing> { typedef _Tp type; };
813template <class _Tp> struct __libcpp_remove_objc_qualifiers<_Tp __unsafe_unretained> { typedef _Tp type; };
814#endif
815
816template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_pointer
817    : public __libcpp_is_pointer<typename __libcpp_remove_objc_qualifiers<typename remove_cv<_Tp>::type>::type> {};
818
819#if _LIBCPP_STD_VER > 14
820template <class _Tp>
821inline constexpr bool is_pointer_v = is_pointer<_Tp>::value;
822#endif
823
824#endif // __has_keyword(__is_pointer)
825
826// is_reference
827
828#if __has_keyword(__is_lvalue_reference) && \
829    __has_keyword(__is_rvalue_reference) && \
830    __has_keyword(__is_reference)
831
832template<class _Tp>
833struct _LIBCPP_TEMPLATE_VIS is_lvalue_reference : _BoolConstant<__is_lvalue_reference(_Tp)> { };
834
835template<class _Tp>
836struct _LIBCPP_TEMPLATE_VIS is_rvalue_reference : _BoolConstant<__is_rvalue_reference(_Tp)> { };
837
838template<class _Tp>
839struct _LIBCPP_TEMPLATE_VIS is_reference : _BoolConstant<__is_reference(_Tp)> { };
840
841#if _LIBCPP_STD_VER > 14
842template <class _Tp>
843inline constexpr bool is_reference_v = __is_reference(_Tp);
844template <class _Tp>
845inline constexpr bool is_lvalue_reference_v = __is_lvalue_reference(_Tp);
846template <class _Tp>
847inline constexpr bool is_rvalue_reference_v = __is_rvalue_reference(_Tp);
848#endif
849
850#else // __has_keyword(__is_lvalue_reference) && etc...
851
852template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_lvalue_reference       : public false_type {};
853template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_lvalue_reference<_Tp&> : public true_type {};
854
855template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_rvalue_reference        : public false_type {};
856template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_rvalue_reference<_Tp&&> : public true_type {};
857
858template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_reference        : public false_type {};
859template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_reference<_Tp&>  : public true_type {};
860template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_reference<_Tp&&> : public true_type {};
861
862#if _LIBCPP_STD_VER > 14
863template <class _Tp>
864inline constexpr bool is_reference_v = is_reference<_Tp>::value;
865
866template <class _Tp>
867inline constexpr bool is_lvalue_reference_v = is_lvalue_reference<_Tp>::value;
868
869template <class _Tp>
870inline constexpr bool is_rvalue_reference_v = is_rvalue_reference<_Tp>::value;
871#endif
872
873#endif // __has_keyword(__is_lvalue_reference) && etc...
874
875// is_union
876
877#if __has_feature(is_union) || defined(_LIBCPP_COMPILER_GCC)
878
879template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_union
880    : public integral_constant<bool, __is_union(_Tp)> {};
881
882#else
883
884template <class _Tp> struct __libcpp_union : public false_type {};
885template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_union
886    : public __libcpp_union<typename remove_cv<_Tp>::type> {};
887
888#endif
889
890#if _LIBCPP_STD_VER > 14
891template <class _Tp>
892inline constexpr bool is_union_v = is_union<_Tp>::value;
893#endif
894
895// is_class
896
897#if __has_feature(is_class) || defined(_LIBCPP_COMPILER_GCC)
898
899template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_class
900    : public integral_constant<bool, __is_class(_Tp)> {};
901
902#else
903
904namespace __is_class_imp
905{
906template <class _Tp> char  __test(int _Tp::*);
907template <class _Tp> __two __test(...);
908}
909
910template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_class
911    : public integral_constant<bool, sizeof(__is_class_imp::__test<_Tp>(0)) == 1 && !is_union<_Tp>::value> {};
912
913#endif
914
915#if _LIBCPP_STD_VER > 14
916template <class _Tp>
917inline constexpr bool is_class_v = is_class<_Tp>::value;
918#endif
919
920// is_function
921
922template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_function
923    : public _BoolConstant<
924#ifdef __clang__
925    __is_function(_Tp)
926#else
927 !(is_reference<_Tp>::value || is_const<const _Tp>::value)
928#endif
929    > {};
930
931
932#if _LIBCPP_STD_VER > 14
933template <class _Tp>
934inline constexpr bool is_function_v = is_function<_Tp>::value;
935#endif
936
937template <class _Tp> struct __libcpp_is_member_pointer {
938  enum {
939    __is_member = false,
940    __is_func = false,
941    __is_obj = false
942  };
943};
944template <class _Tp, class _Up> struct __libcpp_is_member_pointer<_Tp _Up::*> {
945  enum {
946    __is_member = true,
947    __is_func = is_function<_Tp>::value,
948    __is_obj = !__is_func,
949  };
950};
951
952#if __has_keyword(__is_member_function_pointer)
953
954template<class _Tp>
955struct _LIBCPP_TEMPLATE_VIS is_member_function_pointer
956    : _BoolConstant<__is_member_function_pointer(_Tp)> { };
957
958#if _LIBCPP_STD_VER > 14
959template <class _Tp>
960inline constexpr bool is_member_function_pointer_v = __is_member_function_pointer(_Tp);
961#endif
962
963#else // __has_keyword(__is_member_function_pointer)
964
965template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_member_function_pointer
966    : public _BoolConstant< __libcpp_is_member_pointer<typename remove_cv<_Tp>::type>::__is_func > {};
967
968#if _LIBCPP_STD_VER > 14
969template <class _Tp>
970inline constexpr bool is_member_function_pointer_v = is_member_function_pointer<_Tp>::value;
971#endif
972
973#endif // __has_keyword(__is_member_function_pointer)
974
975// is_member_pointer
976
977#if __has_keyword(__is_member_pointer)
978
979template<class _Tp>
980struct _LIBCPP_TEMPLATE_VIS is_member_pointer : _BoolConstant<__is_member_pointer(_Tp)> { };
981
982#if _LIBCPP_STD_VER > 14
983template <class _Tp>
984inline constexpr bool is_member_pointer_v = __is_member_pointer(_Tp);
985#endif
986
987#else // __has_keyword(__is_member_pointer)
988
989template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_member_pointer
990 : public _BoolConstant< __libcpp_is_member_pointer<typename remove_cv<_Tp>::type>::__is_member > {};
991
992#if _LIBCPP_STD_VER > 14
993template <class _Tp>
994inline constexpr bool is_member_pointer_v = is_member_pointer<_Tp>::value;
995#endif
996
997#endif // __has_keyword(__is_member_pointer)
998
999// is_member_object_pointer
1000
1001#if __has_keyword(__is_member_object_pointer)
1002
1003template<class _Tp>
1004struct _LIBCPP_TEMPLATE_VIS is_member_object_pointer
1005    : _BoolConstant<__is_member_object_pointer(_Tp)> { };
1006
1007#if _LIBCPP_STD_VER > 14
1008template <class _Tp>
1009inline constexpr bool is_member_object_pointer_v = __is_member_object_pointer(_Tp);
1010#endif
1011
1012#else // __has_keyword(__is_member_object_pointer)
1013
1014template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_member_object_pointer
1015    : public _BoolConstant< __libcpp_is_member_pointer<typename remove_cv<_Tp>::type>::__is_obj >  {};
1016
1017#if _LIBCPP_STD_VER > 14
1018template <class _Tp>
1019inline constexpr bool is_member_object_pointer_v = is_member_object_pointer<_Tp>::value;
1020#endif
1021
1022#endif // __has_keyword(__is_member_object_pointer)
1023
1024// is_enum
1025
1026#if __has_feature(is_enum) || defined(_LIBCPP_COMPILER_GCC)
1027
1028template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_enum
1029    : public integral_constant<bool, __is_enum(_Tp)> {};
1030
1031#if _LIBCPP_STD_VER > 14
1032template <class _Tp>
1033inline constexpr bool is_enum_v = __is_enum(_Tp);
1034#endif
1035
1036#else
1037
1038template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_enum
1039    : public integral_constant<bool, !is_void<_Tp>::value             &&
1040                                     !is_integral<_Tp>::value         &&
1041                                     !is_floating_point<_Tp>::value   &&
1042                                     !is_array<_Tp>::value            &&
1043                                     !is_pointer<_Tp>::value          &&
1044                                     !is_reference<_Tp>::value        &&
1045                                     !is_member_pointer<_Tp>::value   &&
1046                                     !is_union<_Tp>::value            &&
1047                                     !is_class<_Tp>::value            &&
1048                                     !is_function<_Tp>::value         > {};
1049
1050#if _LIBCPP_STD_VER > 14
1051template <class _Tp>
1052inline constexpr bool is_enum_v = is_enum<_Tp>::value;
1053#endif
1054
1055#endif // __has_feature(is_enum) || defined(_LIBCPP_COMPILER_GCC)
1056
1057// is_arithmetic
1058
1059
1060template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_arithmetic
1061    : public integral_constant<bool, is_integral<_Tp>::value      ||
1062                                     is_floating_point<_Tp>::value> {};
1063
1064#if _LIBCPP_STD_VER > 14
1065template <class _Tp>
1066inline constexpr bool is_arithmetic_v = is_arithmetic<_Tp>::value;
1067#endif
1068
1069// is_fundamental
1070
1071// Before Clang 10, __is_fundamental didn't work for nullptr_t.
1072// In C++03 nullptr_t is library-provided but must still count as "fundamental."
1073#if __has_keyword(__is_fundamental) &&                                         \
1074    !(defined(_LIBCPP_CLANG_VER) && _LIBCPP_CLANG_VER < 1000) &&               \
1075    !defined(_LIBCPP_CXX03_LANG)
1076
1077template<class _Tp>
1078struct _LIBCPP_TEMPLATE_VIS is_fundamental : _BoolConstant<__is_fundamental(_Tp)> { };
1079
1080#if _LIBCPP_STD_VER > 14
1081template <class _Tp>
1082inline constexpr bool is_fundamental_v = __is_fundamental(_Tp);
1083#endif
1084
1085#else // __has_keyword(__is_fundamental)
1086
1087template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_fundamental
1088    : public integral_constant<bool, is_void<_Tp>::value        ||
1089                                     __is_nullptr_t<_Tp>::value ||
1090                                     is_arithmetic<_Tp>::value> {};
1091
1092#if _LIBCPP_STD_VER > 14
1093template <class _Tp>
1094inline constexpr bool is_fundamental_v = is_fundamental<_Tp>::value;
1095#endif
1096
1097#endif // __has_keyword(__is_fundamental)
1098
1099// is_scalar
1100
1101// In C++03 nullptr_t is library-provided but must still count as "scalar."
1102#if __has_keyword(__is_scalar) && !defined(_LIBCPP_CXX03_LANG)
1103
1104template<class _Tp>
1105struct _LIBCPP_TEMPLATE_VIS is_scalar : _BoolConstant<__is_scalar(_Tp)> { };
1106
1107#if _LIBCPP_STD_VER > 14
1108template <class _Tp>
1109inline constexpr bool is_scalar_v = __is_scalar(_Tp);
1110#endif
1111
1112#else // __has_keyword(__is_scalar)
1113
1114template <class _Tp> struct __is_block : false_type {};
1115#if defined(_LIBCPP_HAS_EXTENSION_BLOCKS)
1116template <class _Rp, class ..._Args> struct __is_block<_Rp (^)(_Args...)> : true_type {};
1117#endif
1118
1119template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_scalar
1120    : public integral_constant<bool, is_arithmetic<_Tp>::value     ||
1121                                     is_member_pointer<_Tp>::value ||
1122                                     is_pointer<_Tp>::value        ||
1123                                     __is_nullptr_t<_Tp>::value    ||
1124                                     __is_block<_Tp>::value        ||
1125                                     is_enum<_Tp>::value           > {};
1126
1127template <> struct _LIBCPP_TEMPLATE_VIS is_scalar<nullptr_t> : public true_type {};
1128
1129#if _LIBCPP_STD_VER > 14
1130template <class _Tp>
1131inline constexpr bool is_scalar_v = is_scalar<_Tp>::value;
1132#endif
1133
1134#endif // __has_keyword(__is_scalar)
1135
1136// is_object
1137
1138#if __has_keyword(__is_object)
1139
1140template<class _Tp>
1141struct _LIBCPP_TEMPLATE_VIS is_object : _BoolConstant<__is_object(_Tp)> { };
1142
1143#if _LIBCPP_STD_VER > 14
1144template <class _Tp>
1145inline constexpr bool is_object_v = __is_object(_Tp);
1146#endif
1147
1148#else // __has_keyword(__is_object)
1149
1150template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_object
1151    : public integral_constant<bool, is_scalar<_Tp>::value ||
1152                                     is_array<_Tp>::value  ||
1153                                     is_union<_Tp>::value  ||
1154                                     is_class<_Tp>::value  > {};
1155
1156#if _LIBCPP_STD_VER > 14
1157template <class _Tp>
1158inline constexpr bool is_object_v = is_object<_Tp>::value;
1159#endif
1160
1161#endif // __has_keyword(__is_object)
1162
1163// is_compound
1164
1165// >= 11 because in C++03 nullptr isn't actually nullptr
1166#if __has_keyword(__is_compound) && !defined(_LIBCPP_CXX03_LANG)
1167
1168template<class _Tp>
1169struct _LIBCPP_TEMPLATE_VIS is_compound : _BoolConstant<__is_compound(_Tp)> { };
1170
1171#if _LIBCPP_STD_VER > 14
1172template <class _Tp>
1173inline constexpr bool is_compound_v = __is_compound(_Tp);
1174#endif
1175
1176#else // __has_keyword(__is_compound)
1177
1178template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_compound
1179    : public integral_constant<bool, !is_fundamental<_Tp>::value> {};
1180
1181#if _LIBCPP_STD_VER > 14
1182template <class _Tp>
1183inline constexpr bool is_compound_v = is_compound<_Tp>::value;
1184#endif
1185
1186#endif // __has_keyword(__is_compound)
1187
1188// __is_referenceable  [defns.referenceable]
1189
1190struct __is_referenceable_impl {
1191    template <class _Tp> static _Tp& __test(int);
1192    template <class _Tp> static __two __test(...);
1193};
1194
1195template <class _Tp>
1196struct __is_referenceable : integral_constant<bool,
1197    _IsNotSame<decltype(__is_referenceable_impl::__test<_Tp>(0)), __two>::value> {};
1198
1199
1200// add_const
1201
1202template <class _Tp> struct _LIBCPP_TEMPLATE_VIS add_const {
1203  typedef _LIBCPP_NODEBUG const _Tp type;
1204};
1205
1206#if _LIBCPP_STD_VER > 11
1207template <class _Tp> using add_const_t = typename add_const<_Tp>::type;
1208#endif
1209
1210// add_volatile
1211
1212template <class _Tp> struct _LIBCPP_TEMPLATE_VIS add_volatile {
1213  typedef _LIBCPP_NODEBUG volatile _Tp type;
1214};
1215
1216#if _LIBCPP_STD_VER > 11
1217template <class _Tp> using add_volatile_t = typename add_volatile<_Tp>::type;
1218#endif
1219
1220// add_cv
1221template <class _Tp> struct _LIBCPP_TEMPLATE_VIS add_cv {
1222  typedef _LIBCPP_NODEBUG const volatile _Tp type;
1223};
1224
1225#if _LIBCPP_STD_VER > 11
1226template <class _Tp> using add_cv_t = typename add_cv<_Tp>::type;
1227#endif
1228
1229// remove_reference
1230
1231template <class _Tp> struct _LIBCPP_TEMPLATE_VIS remove_reference        {typedef _LIBCPP_NODEBUG _Tp type;};
1232template <class _Tp> struct _LIBCPP_TEMPLATE_VIS remove_reference<_Tp&>  {typedef _LIBCPP_NODEBUG _Tp type;};
1233template <class _Tp> struct _LIBCPP_TEMPLATE_VIS remove_reference<_Tp&&> {typedef _LIBCPP_NODEBUG _Tp type;};
1234
1235#if _LIBCPP_STD_VER > 11
1236template <class _Tp> using remove_reference_t = typename remove_reference<_Tp>::type;
1237#endif
1238
1239// add_lvalue_reference
1240
1241template <class _Tp, bool = __is_referenceable<_Tp>::value> struct __add_lvalue_reference_impl            { typedef _LIBCPP_NODEBUG _Tp  type; };
1242template <class _Tp                                       > struct __add_lvalue_reference_impl<_Tp, true> { typedef _LIBCPP_NODEBUG _Tp& type; };
1243
1244template <class _Tp> struct _LIBCPP_TEMPLATE_VIS add_lvalue_reference
1245{typedef _LIBCPP_NODEBUG typename  __add_lvalue_reference_impl<_Tp>::type type;};
1246
1247#if _LIBCPP_STD_VER > 11
1248template <class _Tp> using add_lvalue_reference_t = typename add_lvalue_reference<_Tp>::type;
1249#endif
1250
1251template <class _Tp, bool = __is_referenceable<_Tp>::value> struct __add_rvalue_reference_impl            { typedef _LIBCPP_NODEBUG _Tp   type; };
1252template <class _Tp                                       > struct __add_rvalue_reference_impl<_Tp, true> { typedef _LIBCPP_NODEBUG _Tp&& type; };
1253
1254template <class _Tp> struct _LIBCPP_TEMPLATE_VIS add_rvalue_reference
1255{typedef _LIBCPP_NODEBUG typename __add_rvalue_reference_impl<_Tp>::type type;};
1256
1257#if _LIBCPP_STD_VER > 11
1258template <class _Tp> using add_rvalue_reference_t = typename add_rvalue_reference<_Tp>::type;
1259#endif
1260
1261// Suppress deprecation notice for volatile-qualified return type resulting
1262// from volatile-qualified types _Tp.
1263_LIBCPP_SUPPRESS_DEPRECATED_PUSH
1264template <class _Tp> _Tp&& __declval(int);
1265template <class _Tp> _Tp   __declval(long);
1266_LIBCPP_SUPPRESS_DEPRECATED_POP
1267
1268template <class _Tp>
1269decltype(__declval<_Tp>(0))
1270declval() _NOEXCEPT;
1271
1272template <class _Tp>
1273struct __unconstref {
1274    typedef _LIBCPP_NODEBUG typename remove_const<typename remove_reference<_Tp>::type>::type type;
1275};
1276
1277template <class _Tp>
1278using __uncvref_t _LIBCPP_NODEBUG = typename remove_cv<typename remove_reference<_Tp>::type>::type;
1279
1280// __is_same_uncvref
1281
1282template <class _Tp, class _Up>
1283struct __is_same_uncvref : _IsSame<__uncvref_t<_Tp>, __uncvref_t<_Up> > {};
1284
1285#if _LIBCPP_STD_VER > 17
1286// remove_cvref - same as __uncvref
1287template <class _Tp>
1288struct remove_cvref {
1289    using type _LIBCPP_NODEBUG = __uncvref_t<_Tp>;
1290};
1291
1292template <class _Tp> using remove_cvref_t = typename remove_cvref<_Tp>::type;
1293#endif
1294
1295
1296struct __any
1297{
1298    __any(...);
1299};
1300
1301// remove_pointer
1302
1303template <class _Tp> struct _LIBCPP_TEMPLATE_VIS remove_pointer                      {typedef _LIBCPP_NODEBUG _Tp type;};
1304template <class _Tp> struct _LIBCPP_TEMPLATE_VIS remove_pointer<_Tp*>                {typedef _LIBCPP_NODEBUG _Tp type;};
1305template <class _Tp> struct _LIBCPP_TEMPLATE_VIS remove_pointer<_Tp* const>          {typedef _LIBCPP_NODEBUG _Tp type;};
1306template <class _Tp> struct _LIBCPP_TEMPLATE_VIS remove_pointer<_Tp* volatile>       {typedef _LIBCPP_NODEBUG _Tp type;};
1307template <class _Tp> struct _LIBCPP_TEMPLATE_VIS remove_pointer<_Tp* const volatile> {typedef _LIBCPP_NODEBUG _Tp type;};
1308
1309#if _LIBCPP_STD_VER > 11
1310template <class _Tp> using remove_pointer_t = typename remove_pointer<_Tp>::type;
1311#endif
1312
1313// add_pointer
1314
1315template <class _Tp,
1316        bool = __is_referenceable<_Tp>::value ||
1317                _IsSame<typename remove_cv<_Tp>::type, void>::value>
1318struct __add_pointer_impl
1319    {typedef _LIBCPP_NODEBUG typename remove_reference<_Tp>::type* type;};
1320template <class _Tp> struct __add_pointer_impl<_Tp, false>
1321    {typedef _LIBCPP_NODEBUG _Tp type;};
1322
1323template <class _Tp> struct _LIBCPP_TEMPLATE_VIS add_pointer
1324    {typedef _LIBCPP_NODEBUG typename __add_pointer_impl<_Tp>::type type;};
1325
1326#if _LIBCPP_STD_VER > 11
1327template <class _Tp> using add_pointer_t = typename add_pointer<_Tp>::type;
1328#endif
1329
1330// type_identity
1331
1332template <class _Tp>
1333struct __type_identity { typedef _Tp type; };
1334
1335template <class _Tp>
1336using __type_identity_t _LIBCPP_NODEBUG = typename __type_identity<_Tp>::type;
1337
1338#if _LIBCPP_STD_VER > 17
1339template<class _Tp> struct type_identity { typedef _Tp type; };
1340template<class _Tp> using type_identity_t = typename type_identity<_Tp>::type;
1341#endif
1342
1343// is_signed
1344
1345#if __has_keyword(__is_signed)
1346
1347template<class _Tp>
1348struct _LIBCPP_TEMPLATE_VIS is_signed : _BoolConstant<__is_signed(_Tp)> { };
1349
1350#if _LIBCPP_STD_VER > 14
1351template <class _Tp>
1352inline constexpr bool is_signed_v = __is_signed(_Tp);
1353#endif
1354
1355#else // __has_keyword(__is_signed)
1356
1357template <class _Tp, bool = is_integral<_Tp>::value>
1358struct __libcpp_is_signed_impl : public _BoolConstant<(_Tp(-1) < _Tp(0))> {};
1359
1360template <class _Tp>
1361struct __libcpp_is_signed_impl<_Tp, false> : public true_type {};  // floating point
1362
1363template <class _Tp, bool = is_arithmetic<_Tp>::value>
1364struct __libcpp_is_signed : public __libcpp_is_signed_impl<_Tp> {};
1365
1366template <class _Tp> struct __libcpp_is_signed<_Tp, false> : public false_type {};
1367
1368template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_signed : public __libcpp_is_signed<_Tp> {};
1369
1370#if _LIBCPP_STD_VER > 14
1371template <class _Tp>
1372inline constexpr bool is_signed_v = is_signed<_Tp>::value;
1373#endif
1374
1375#endif // __has_keyword(__is_signed)
1376
1377// is_unsigned
1378
1379// Before Clang 13, __is_unsigned returned true for enums with signed underlying type.
1380// No currently-released version of AppleClang contains the fixed intrinsic.
1381#if __has_keyword(__is_unsigned) &&                                            \
1382    !(defined(_LIBCPP_CLANG_VER) && _LIBCPP_CLANG_VER < 1300) &&               \
1383    !defined(_LIBCPP_APPLE_CLANG_VER)
1384
1385template<class _Tp>
1386struct _LIBCPP_TEMPLATE_VIS is_unsigned : _BoolConstant<__is_unsigned(_Tp)> { };
1387
1388#if _LIBCPP_STD_VER > 14
1389template <class _Tp>
1390inline constexpr bool is_unsigned_v = __is_unsigned(_Tp);
1391#endif
1392
1393#else // __has_keyword(__is_unsigned)
1394
1395template <class _Tp, bool = is_integral<_Tp>::value>
1396struct __libcpp_is_unsigned_impl : public _BoolConstant<(_Tp(0) < _Tp(-1))> {};
1397
1398template <class _Tp>
1399struct __libcpp_is_unsigned_impl<_Tp, false> : public false_type {};  // floating point
1400
1401template <class _Tp, bool = is_arithmetic<_Tp>::value>
1402struct __libcpp_is_unsigned : public __libcpp_is_unsigned_impl<_Tp> {};
1403
1404template <class _Tp> struct __libcpp_is_unsigned<_Tp, false> : public false_type {};
1405
1406template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_unsigned : public __libcpp_is_unsigned<_Tp> {};
1407
1408#if _LIBCPP_STD_VER > 14
1409template <class _Tp>
1410inline constexpr bool is_unsigned_v = is_unsigned<_Tp>::value;
1411#endif
1412
1413#endif // __has_keyword(__is_unsigned)
1414
1415// rank
1416
1417template <class _Tp> struct _LIBCPP_TEMPLATE_VIS rank
1418    : public integral_constant<size_t, 0> {};
1419template <class _Tp> struct _LIBCPP_TEMPLATE_VIS rank<_Tp[]>
1420    : public integral_constant<size_t, rank<_Tp>::value + 1> {};
1421template <class _Tp, size_t _Np> struct _LIBCPP_TEMPLATE_VIS rank<_Tp[_Np]>
1422    : public integral_constant<size_t, rank<_Tp>::value + 1> {};
1423
1424#if _LIBCPP_STD_VER > 14
1425template <class _Tp>
1426inline constexpr size_t rank_v = rank<_Tp>::value;
1427#endif
1428
1429// extent
1430
1431#if __has_keyword(__array_extent)
1432
1433template<class _Tp, size_t _Dim = 0>
1434struct _LIBCPP_TEMPLATE_VIS extent
1435    : integral_constant<size_t, __array_extent(_Tp, _Dim)> { };
1436
1437#if _LIBCPP_STD_VER > 14
1438template <class _Tp, unsigned _Ip = 0>
1439inline constexpr size_t extent_v = __array_extent(_Tp, _Ip);
1440#endif
1441
1442#else // __has_keyword(__array_extent)
1443
1444template <class _Tp, unsigned _Ip = 0> struct _LIBCPP_TEMPLATE_VIS extent
1445    : public integral_constant<size_t, 0> {};
1446template <class _Tp> struct _LIBCPP_TEMPLATE_VIS extent<_Tp[], 0>
1447    : public integral_constant<size_t, 0> {};
1448template <class _Tp, unsigned _Ip> struct _LIBCPP_TEMPLATE_VIS extent<_Tp[], _Ip>
1449    : public integral_constant<size_t, extent<_Tp, _Ip-1>::value> {};
1450template <class _Tp, size_t _Np> struct _LIBCPP_TEMPLATE_VIS extent<_Tp[_Np], 0>
1451    : public integral_constant<size_t, _Np> {};
1452template <class _Tp, size_t _Np, unsigned _Ip> struct _LIBCPP_TEMPLATE_VIS extent<_Tp[_Np], _Ip>
1453    : public integral_constant<size_t, extent<_Tp, _Ip-1>::value> {};
1454
1455#if _LIBCPP_STD_VER > 14
1456template <class _Tp, unsigned _Ip = 0>
1457inline constexpr size_t extent_v = extent<_Tp, _Ip>::value;
1458#endif
1459
1460#endif // __has_keyword(__array_extent)
1461
1462// remove_extent
1463
1464template <class _Tp> struct _LIBCPP_TEMPLATE_VIS remove_extent
1465    {typedef _Tp type;};
1466template <class _Tp> struct _LIBCPP_TEMPLATE_VIS remove_extent<_Tp[]>
1467    {typedef _Tp type;};
1468template <class _Tp, size_t _Np> struct _LIBCPP_TEMPLATE_VIS remove_extent<_Tp[_Np]>
1469    {typedef _Tp type;};
1470
1471#if _LIBCPP_STD_VER > 11
1472template <class _Tp> using remove_extent_t = typename remove_extent<_Tp>::type;
1473#endif
1474
1475// remove_all_extents
1476
1477template <class _Tp> struct _LIBCPP_TEMPLATE_VIS remove_all_extents
1478    {typedef _Tp type;};
1479template <class _Tp> struct _LIBCPP_TEMPLATE_VIS remove_all_extents<_Tp[]>
1480    {typedef typename remove_all_extents<_Tp>::type type;};
1481template <class _Tp, size_t _Np> struct _LIBCPP_TEMPLATE_VIS remove_all_extents<_Tp[_Np]>
1482    {typedef typename remove_all_extents<_Tp>::type type;};
1483
1484#if _LIBCPP_STD_VER > 11
1485template <class _Tp> using remove_all_extents_t = typename remove_all_extents<_Tp>::type;
1486#endif
1487
1488#if _LIBCPP_STD_VER > 17
1489// is_bounded_array
1490
1491template <class>                 struct _LIBCPP_TEMPLATE_VIS is_bounded_array           : false_type {};
1492template <class _Tp, size_t _Np> struct _LIBCPP_TEMPLATE_VIS is_bounded_array<_Tp[_Np]> : true_type {};
1493
1494template <class _Tp>
1495inline constexpr
1496bool is_bounded_array_v  = is_bounded_array<_Tp>::value;
1497
1498// is_unbounded_array
1499
1500template <class>     struct _LIBCPP_TEMPLATE_VIS is_unbounded_array        : false_type {};
1501template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_unbounded_array<_Tp[]> : true_type {};
1502
1503template <class _Tp>
1504inline constexpr
1505bool is_unbounded_array_v  = is_unbounded_array<_Tp>::value;
1506#endif
1507
1508// decay
1509
1510template <class _Up, bool>
1511struct __decay {
1512    typedef _LIBCPP_NODEBUG typename remove_cv<_Up>::type type;
1513};
1514
1515template <class _Up>
1516struct __decay<_Up, true> {
1517public:
1518    typedef _LIBCPP_NODEBUG typename conditional
1519                     <
1520                         is_array<_Up>::value,
1521                         typename remove_extent<_Up>::type*,
1522                         typename conditional
1523                         <
1524                              is_function<_Up>::value,
1525                              typename add_pointer<_Up>::type,
1526                              typename remove_cv<_Up>::type
1527                         >::type
1528                     >::type type;
1529};
1530
1531template <class _Tp>
1532struct _LIBCPP_TEMPLATE_VIS decay
1533{
1534private:
1535    typedef _LIBCPP_NODEBUG typename remove_reference<_Tp>::type _Up;
1536public:
1537    typedef _LIBCPP_NODEBUG typename __decay<_Up, __is_referenceable<_Up>::value>::type type;
1538};
1539
1540#if _LIBCPP_STD_VER > 11
1541template <class _Tp> using decay_t = typename decay<_Tp>::type;
1542#endif
1543
1544// is_abstract
1545
1546template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_abstract
1547    : public integral_constant<bool, __is_abstract(_Tp)> {};
1548
1549#if _LIBCPP_STD_VER > 14
1550template <class _Tp>
1551inline constexpr bool is_abstract_v = is_abstract<_Tp>::value;
1552#endif
1553
1554// is_final
1555
1556template <class _Tp> struct _LIBCPP_TEMPLATE_VIS
1557__libcpp_is_final : public integral_constant<bool, __is_final(_Tp)> {};
1558
1559#if _LIBCPP_STD_VER > 11
1560template <class _Tp> struct _LIBCPP_TEMPLATE_VIS
1561is_final : public integral_constant<bool, __is_final(_Tp)> {};
1562#endif
1563
1564#if _LIBCPP_STD_VER > 14
1565template <class _Tp>
1566inline constexpr bool is_final_v = is_final<_Tp>::value;
1567#endif
1568
1569// is_aggregate
1570#if _LIBCPP_STD_VER > 14
1571
1572template <class _Tp> struct _LIBCPP_TEMPLATE_VIS
1573is_aggregate : public integral_constant<bool, __is_aggregate(_Tp)> {};
1574
1575template <class _Tp>
1576inline constexpr bool is_aggregate_v = is_aggregate<_Tp>::value;
1577
1578#endif // _LIBCPP_STD_VER > 14
1579
1580// is_base_of
1581
1582template <class _Bp, class _Dp>
1583struct _LIBCPP_TEMPLATE_VIS is_base_of
1584    : public integral_constant<bool, __is_base_of(_Bp, _Dp)> {};
1585
1586#if _LIBCPP_STD_VER > 14
1587template <class _Bp, class _Dp>
1588inline constexpr bool is_base_of_v = is_base_of<_Bp, _Dp>::value;
1589#endif
1590
1591// __is_core_convertible
1592
1593// [conv.general]/3 says "E is convertible to T" whenever "T t=E;" is well-formed.
1594// We can't test for that, but we can test implicit convertibility by passing it
1595// to a function. Notice that __is_core_convertible<void,void> is false,
1596// and __is_core_convertible<immovable-type,immovable-type> is true in C++17 and later.
1597
1598template <class _Tp, class _Up, class = void>
1599struct __is_core_convertible : public false_type {};
1600
1601template <class _Tp, class _Up>
1602struct __is_core_convertible<_Tp, _Up, decltype(
1603    static_cast<void(*)(_Up)>(0) ( static_cast<_Tp(*)()>(0)() )
1604)> : public true_type {};
1605
1606// is_convertible
1607
1608#if __has_feature(is_convertible_to) && !defined(_LIBCPP_USE_IS_CONVERTIBLE_FALLBACK)
1609
1610template <class _T1, class _T2> struct _LIBCPP_TEMPLATE_VIS is_convertible
1611    : public integral_constant<bool, __is_convertible_to(_T1, _T2)> {};
1612
1613#else  // __has_feature(is_convertible_to)
1614
1615namespace __is_convertible_imp
1616{
1617template <class _Tp> void  __test_convert(_Tp);
1618
1619template <class _From, class _To, class = void>
1620struct __is_convertible_test : public false_type {};
1621
1622template <class _From, class _To>
1623struct __is_convertible_test<_From, _To,
1624    decltype(__is_convertible_imp::__test_convert<_To>(declval<_From>()))> : public true_type
1625{};
1626
1627template <class _Tp, bool _IsArray =    is_array<_Tp>::value,
1628                     bool _IsFunction = is_function<_Tp>::value,
1629                     bool _IsVoid =     is_void<_Tp>::value>
1630                     struct __is_array_function_or_void                          {enum {value = 0};};
1631template <class _Tp> struct __is_array_function_or_void<_Tp, true, false, false> {enum {value = 1};};
1632template <class _Tp> struct __is_array_function_or_void<_Tp, false, true, false> {enum {value = 2};};
1633template <class _Tp> struct __is_array_function_or_void<_Tp, false, false, true> {enum {value = 3};};
1634}
1635
1636template <class _Tp,
1637    unsigned = __is_convertible_imp::__is_array_function_or_void<typename remove_reference<_Tp>::type>::value>
1638struct __is_convertible_check
1639{
1640    static const size_t __v = 0;
1641};
1642
1643template <class _Tp>
1644struct __is_convertible_check<_Tp, 0>
1645{
1646    static const size_t __v = sizeof(_Tp);
1647};
1648
1649template <class _T1, class _T2,
1650    unsigned _T1_is_array_function_or_void = __is_convertible_imp::__is_array_function_or_void<_T1>::value,
1651    unsigned _T2_is_array_function_or_void = __is_convertible_imp::__is_array_function_or_void<_T2>::value>
1652struct __is_convertible
1653    : public integral_constant<bool,
1654        __is_convertible_imp::__is_convertible_test<_T1, _T2>::value
1655    >
1656{};
1657
1658template <class _T1, class _T2> struct __is_convertible<_T1, _T2, 0, 1> : public false_type {};
1659template <class _T1, class _T2> struct __is_convertible<_T1, _T2, 1, 1> : public false_type {};
1660template <class _T1, class _T2> struct __is_convertible<_T1, _T2, 2, 1> : public false_type {};
1661template <class _T1, class _T2> struct __is_convertible<_T1, _T2, 3, 1> : public false_type {};
1662
1663template <class _T1, class _T2> struct __is_convertible<_T1, _T2, 0, 2> : public false_type {};
1664template <class _T1, class _T2> struct __is_convertible<_T1, _T2, 1, 2> : public false_type {};
1665template <class _T1, class _T2> struct __is_convertible<_T1, _T2, 2, 2> : public false_type {};
1666template <class _T1, class _T2> struct __is_convertible<_T1, _T2, 3, 2> : public false_type {};
1667
1668template <class _T1, class _T2> struct __is_convertible<_T1, _T2, 0, 3> : public false_type {};
1669template <class _T1, class _T2> struct __is_convertible<_T1, _T2, 1, 3> : public false_type {};
1670template <class _T1, class _T2> struct __is_convertible<_T1, _T2, 2, 3> : public false_type {};
1671template <class _T1, class _T2> struct __is_convertible<_T1, _T2, 3, 3> : public true_type {};
1672
1673template <class _T1, class _T2> struct _LIBCPP_TEMPLATE_VIS is_convertible
1674    : public __is_convertible<_T1, _T2>
1675{
1676    static const size_t __complete_check1 = __is_convertible_check<_T1>::__v;
1677    static const size_t __complete_check2 = __is_convertible_check<_T2>::__v;
1678};
1679
1680#endif // __has_feature(is_convertible_to)
1681
1682#if _LIBCPP_STD_VER > 14
1683template <class _From, class _To>
1684inline constexpr bool is_convertible_v = is_convertible<_From, _To>::value;
1685#endif
1686
1687// is_nothrow_convertible
1688
1689#if _LIBCPP_STD_VER > 17
1690
1691template <typename _Tp>
1692static void __test_noexcept(_Tp) noexcept;
1693
1694template<typename _Fm, typename _To>
1695static bool_constant<noexcept(_VSTD::__test_noexcept<_To>(declval<_Fm>()))>
1696__is_nothrow_convertible_test();
1697
1698template <typename _Fm, typename _To>
1699struct __is_nothrow_convertible_helper: decltype(__is_nothrow_convertible_test<_Fm, _To>())
1700{ };
1701
1702template <typename _Fm, typename _To>
1703struct is_nothrow_convertible : _Or<
1704    _And<is_void<_To>, is_void<_Fm>>,
1705    _Lazy<_And, is_convertible<_Fm, _To>, __is_nothrow_convertible_helper<_Fm, _To>>
1706>::type { };
1707
1708template <typename _Fm, typename _To>
1709inline constexpr bool is_nothrow_convertible_v = is_nothrow_convertible<_Fm, _To>::value;
1710
1711#endif // _LIBCPP_STD_VER > 17
1712
1713// is_empty
1714
1715#if __has_feature(is_empty) || defined(_LIBCPP_COMPILER_GCC)
1716
1717template <class _Tp>
1718struct _LIBCPP_TEMPLATE_VIS is_empty
1719    : public integral_constant<bool, __is_empty(_Tp)> {};
1720
1721#else  // __has_feature(is_empty)
1722
1723template <class _Tp>
1724struct __is_empty1
1725    : public _Tp
1726{
1727    double __lx;
1728};
1729
1730struct __is_empty2
1731{
1732    double __lx;
1733};
1734
1735template <class _Tp, bool = is_class<_Tp>::value>
1736struct __libcpp_empty : public integral_constant<bool, sizeof(__is_empty1<_Tp>) == sizeof(__is_empty2)> {};
1737
1738template <class _Tp> struct __libcpp_empty<_Tp, false> : public false_type {};
1739
1740template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_empty : public __libcpp_empty<_Tp> {};
1741
1742#endif // __has_feature(is_empty)
1743
1744#if _LIBCPP_STD_VER > 14
1745template <class _Tp>
1746inline constexpr bool is_empty_v = is_empty<_Tp>::value;
1747#endif
1748
1749// is_polymorphic
1750
1751#if __has_feature(is_polymorphic) || defined(_LIBCPP_COMPILER_MSVC)
1752
1753template <class _Tp>
1754struct _LIBCPP_TEMPLATE_VIS is_polymorphic
1755    : public integral_constant<bool, __is_polymorphic(_Tp)> {};
1756
1757#else
1758
1759template<typename _Tp> char &__is_polymorphic_impl(
1760    typename enable_if<sizeof((_Tp*)dynamic_cast<const volatile void*>(declval<_Tp*>())) != 0,
1761                       int>::type);
1762template<typename _Tp> __two &__is_polymorphic_impl(...);
1763
1764template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_polymorphic
1765    : public integral_constant<bool, sizeof(__is_polymorphic_impl<_Tp>(0)) == 1> {};
1766
1767#endif // __has_feature(is_polymorphic)
1768
1769#if _LIBCPP_STD_VER > 14
1770template <class _Tp>
1771inline constexpr bool is_polymorphic_v = is_polymorphic<_Tp>::value;
1772#endif
1773
1774// has_virtual_destructor
1775
1776#if __has_feature(has_virtual_destructor) || defined(_LIBCPP_COMPILER_GCC)
1777
1778template <class _Tp> struct _LIBCPP_TEMPLATE_VIS has_virtual_destructor
1779    : public integral_constant<bool, __has_virtual_destructor(_Tp)> {};
1780
1781#else
1782
1783template <class _Tp> struct _LIBCPP_TEMPLATE_VIS has_virtual_destructor
1784    : public false_type {};
1785
1786#endif
1787
1788#if _LIBCPP_STD_VER > 14
1789template <class _Tp>
1790inline constexpr bool has_virtual_destructor_v = has_virtual_destructor<_Tp>::value;
1791#endif
1792
1793// has_unique_object_representations
1794
1795#if _LIBCPP_STD_VER > 14
1796
1797template <class _Tp> struct _LIBCPP_TEMPLATE_VIS has_unique_object_representations
1798    : public integral_constant<bool,
1799       __has_unique_object_representations(remove_cv_t<remove_all_extents_t<_Tp>>)> {};
1800
1801template <class _Tp>
1802inline constexpr bool has_unique_object_representations_v = has_unique_object_representations<_Tp>::value;
1803
1804#endif
1805
1806// alignment_of
1807
1808template <class _Tp> struct _LIBCPP_TEMPLATE_VIS alignment_of
1809    : public integral_constant<size_t, _LIBCPP_ALIGNOF(_Tp)> {};
1810
1811#if _LIBCPP_STD_VER > 14
1812template <class _Tp>
1813inline constexpr size_t alignment_of_v = alignment_of<_Tp>::value;
1814#endif
1815
1816// aligned_storage
1817
1818template <class _Hp, class _Tp>
1819struct __type_list
1820{
1821    typedef _Hp _Head;
1822    typedef _Tp _Tail;
1823};
1824
1825struct __nat
1826{
1827#ifndef _LIBCPP_CXX03_LANG
1828    __nat() = delete;
1829    __nat(const __nat&) = delete;
1830    __nat& operator=(const __nat&) = delete;
1831    ~__nat() = delete;
1832#endif
1833};
1834
1835template <class _Tp>
1836struct __align_type
1837{
1838    static const size_t value = _LIBCPP_PREFERRED_ALIGNOF(_Tp);
1839    typedef _Tp type;
1840};
1841
1842struct __struct_double {long double __lx;};
1843struct __struct_double4 {double __lx[4];};
1844
1845typedef
1846    __type_list<__align_type<unsigned char>,
1847    __type_list<__align_type<unsigned short>,
1848    __type_list<__align_type<unsigned int>,
1849    __type_list<__align_type<unsigned long>,
1850    __type_list<__align_type<unsigned long long>,
1851    __type_list<__align_type<double>,
1852    __type_list<__align_type<long double>,
1853    __type_list<__align_type<__struct_double>,
1854    __type_list<__align_type<__struct_double4>,
1855    __type_list<__align_type<int*>,
1856    __nat
1857    > > > > > > > > > > __all_types;
1858
1859template <size_t _Align>
1860struct _ALIGNAS(_Align) __fallback_overaligned {};
1861
1862template <class _TL, size_t _Align> struct __find_pod;
1863
1864template <class _Hp, size_t _Align>
1865struct __find_pod<__type_list<_Hp, __nat>, _Align>
1866{
1867    typedef typename conditional<
1868                             _Align == _Hp::value,
1869                             typename _Hp::type,
1870                             __fallback_overaligned<_Align>
1871                         >::type type;
1872};
1873
1874template <class _Hp, class _Tp, size_t _Align>
1875struct __find_pod<__type_list<_Hp, _Tp>, _Align>
1876{
1877    typedef typename conditional<
1878                             _Align == _Hp::value,
1879                             typename _Hp::type,
1880                             typename __find_pod<_Tp, _Align>::type
1881                         >::type type;
1882};
1883
1884template <class _TL, size_t _Len> struct __find_max_align;
1885
1886template <class _Hp, size_t _Len>
1887struct __find_max_align<__type_list<_Hp, __nat>, _Len> : public integral_constant<size_t, _Hp::value> {};
1888
1889template <size_t _Len, size_t _A1, size_t _A2>
1890struct __select_align
1891{
1892private:
1893    static const size_t __min = _A2 < _A1 ? _A2 : _A1;
1894    static const size_t __max = _A1 < _A2 ? _A2 : _A1;
1895public:
1896    static const size_t value = _Len < __max ? __min : __max;
1897};
1898
1899template <class _Hp, class _Tp, size_t _Len>
1900struct __find_max_align<__type_list<_Hp, _Tp>, _Len>
1901    : public integral_constant<size_t, __select_align<_Len, _Hp::value, __find_max_align<_Tp, _Len>::value>::value> {};
1902
1903template <size_t _Len, size_t _Align = __find_max_align<__all_types, _Len>::value>
1904struct _LIBCPP_TEMPLATE_VIS aligned_storage
1905{
1906    typedef typename __find_pod<__all_types, _Align>::type _Aligner;
1907    union type
1908    {
1909        _Aligner __align;
1910        unsigned char __data[(_Len + _Align - 1)/_Align * _Align];
1911    };
1912};
1913
1914#if _LIBCPP_STD_VER > 11
1915template <size_t _Len, size_t _Align = __find_max_align<__all_types, _Len>::value>
1916    using aligned_storage_t = typename aligned_storage<_Len, _Align>::type;
1917#endif
1918
1919#define _CREATE_ALIGNED_STORAGE_SPECIALIZATION(n) \
1920template <size_t _Len>\
1921struct _LIBCPP_TEMPLATE_VIS aligned_storage<_Len, n>\
1922{\
1923    struct _ALIGNAS(n) type\
1924    {\
1925        unsigned char __lx[(_Len + n - 1)/n * n];\
1926    };\
1927}
1928
1929_CREATE_ALIGNED_STORAGE_SPECIALIZATION(0x1);
1930_CREATE_ALIGNED_STORAGE_SPECIALIZATION(0x2);
1931_CREATE_ALIGNED_STORAGE_SPECIALIZATION(0x4);
1932_CREATE_ALIGNED_STORAGE_SPECIALIZATION(0x8);
1933_CREATE_ALIGNED_STORAGE_SPECIALIZATION(0x10);
1934_CREATE_ALIGNED_STORAGE_SPECIALIZATION(0x20);
1935_CREATE_ALIGNED_STORAGE_SPECIALIZATION(0x40);
1936_CREATE_ALIGNED_STORAGE_SPECIALIZATION(0x80);
1937_CREATE_ALIGNED_STORAGE_SPECIALIZATION(0x100);
1938_CREATE_ALIGNED_STORAGE_SPECIALIZATION(0x200);
1939_CREATE_ALIGNED_STORAGE_SPECIALIZATION(0x400);
1940_CREATE_ALIGNED_STORAGE_SPECIALIZATION(0x800);
1941_CREATE_ALIGNED_STORAGE_SPECIALIZATION(0x1000);
1942_CREATE_ALIGNED_STORAGE_SPECIALIZATION(0x2000);
1943// PE/COFF does not support alignment beyond 8192 (=0x2000)
1944#if !defined(_LIBCPP_OBJECT_FORMAT_COFF)
1945_CREATE_ALIGNED_STORAGE_SPECIALIZATION(0x4000);
1946#endif // !defined(_LIBCPP_OBJECT_FORMAT_COFF)
1947
1948#undef _CREATE_ALIGNED_STORAGE_SPECIALIZATION
1949
1950
1951// aligned_union
1952
1953template <size_t _I0, size_t ..._In>
1954struct __static_max;
1955
1956template <size_t _I0>
1957struct __static_max<_I0>
1958{
1959    static const size_t value = _I0;
1960};
1961
1962template <size_t _I0, size_t _I1, size_t ..._In>
1963struct __static_max<_I0, _I1, _In...>
1964{
1965    static const size_t value = _I0 >= _I1 ? __static_max<_I0, _In...>::value :
1966                                             __static_max<_I1, _In...>::value;
1967};
1968
1969template <size_t _Len, class _Type0, class ..._Types>
1970struct aligned_union
1971{
1972    static const size_t alignment_value = __static_max<_LIBCPP_PREFERRED_ALIGNOF(_Type0),
1973                                                       _LIBCPP_PREFERRED_ALIGNOF(_Types)...>::value;
1974    static const size_t __len = __static_max<_Len, sizeof(_Type0),
1975                                             sizeof(_Types)...>::value;
1976    typedef typename aligned_storage<__len, alignment_value>::type type;
1977};
1978
1979#if _LIBCPP_STD_VER > 11
1980template <size_t _Len, class ..._Types> using aligned_union_t = typename aligned_union<_Len, _Types...>::type;
1981#endif
1982
1983template <class _Tp>
1984struct __numeric_type
1985{
1986   static void __test(...);
1987   static float __test(float);
1988   static double __test(char);
1989   static double __test(int);
1990   static double __test(unsigned);
1991   static double __test(long);
1992   static double __test(unsigned long);
1993   static double __test(long long);
1994   static double __test(unsigned long long);
1995   static double __test(double);
1996   static long double __test(long double);
1997
1998   typedef decltype(__test(declval<_Tp>())) type;
1999   static const bool value = _IsNotSame<type, void>::value;
2000};
2001
2002template <>
2003struct __numeric_type<void>
2004{
2005   static const bool value = true;
2006};
2007
2008// __promote
2009
2010template <class _A1, class _A2 = void, class _A3 = void,
2011          bool = __numeric_type<_A1>::value &&
2012                 __numeric_type<_A2>::value &&
2013                 __numeric_type<_A3>::value>
2014class __promote_imp
2015{
2016public:
2017    static const bool value = false;
2018};
2019
2020template <class _A1, class _A2, class _A3>
2021class __promote_imp<_A1, _A2, _A3, true>
2022{
2023private:
2024    typedef typename __promote_imp<_A1>::type __type1;
2025    typedef typename __promote_imp<_A2>::type __type2;
2026    typedef typename __promote_imp<_A3>::type __type3;
2027public:
2028    typedef decltype(__type1() + __type2() + __type3()) type;
2029    static const bool value = true;
2030};
2031
2032template <class _A1, class _A2>
2033class __promote_imp<_A1, _A2, void, true>
2034{
2035private:
2036    typedef typename __promote_imp<_A1>::type __type1;
2037    typedef typename __promote_imp<_A2>::type __type2;
2038public:
2039    typedef decltype(__type1() + __type2()) type;
2040    static const bool value = true;
2041};
2042
2043template <class _A1>
2044class __promote_imp<_A1, void, void, true>
2045{
2046public:
2047    typedef typename __numeric_type<_A1>::type type;
2048    static const bool value = true;
2049};
2050
2051template <class _A1, class _A2 = void, class _A3 = void>
2052class __promote : public __promote_imp<_A1, _A2, _A3> {};
2053
2054// make_signed / make_unsigned
2055
2056typedef
2057    __type_list<signed char,
2058    __type_list<signed short,
2059    __type_list<signed int,
2060    __type_list<signed long,
2061    __type_list<signed long long,
2062#ifndef _LIBCPP_HAS_NO_INT128
2063    __type_list<__int128_t,
2064#endif
2065    __nat
2066#ifndef _LIBCPP_HAS_NO_INT128
2067    >
2068#endif
2069    > > > > > __signed_types;
2070
2071typedef
2072    __type_list<unsigned char,
2073    __type_list<unsigned short,
2074    __type_list<unsigned int,
2075    __type_list<unsigned long,
2076    __type_list<unsigned long long,
2077#ifndef _LIBCPP_HAS_NO_INT128
2078    __type_list<__uint128_t,
2079#endif
2080    __nat
2081#ifndef _LIBCPP_HAS_NO_INT128
2082    >
2083#endif
2084    > > > > > __unsigned_types;
2085
2086template <class _TypeList, size_t _Size, bool = _Size <= sizeof(typename _TypeList::_Head)> struct __find_first;
2087
2088template <class _Hp, class _Tp, size_t _Size>
2089struct __find_first<__type_list<_Hp, _Tp>, _Size, true>
2090{
2091    typedef _LIBCPP_NODEBUG _Hp type;
2092};
2093
2094template <class _Hp, class _Tp, size_t _Size>
2095struct __find_first<__type_list<_Hp, _Tp>, _Size, false>
2096{
2097    typedef _LIBCPP_NODEBUG typename __find_first<_Tp, _Size>::type type;
2098};
2099
2100template <class _Tp, class _Up, bool = is_const<typename remove_reference<_Tp>::type>::value,
2101                             bool = is_volatile<typename remove_reference<_Tp>::type>::value>
2102struct __apply_cv
2103{
2104    typedef _LIBCPP_NODEBUG _Up type;
2105};
2106
2107template <class _Tp, class _Up>
2108struct __apply_cv<_Tp, _Up, true, false>
2109{
2110    typedef _LIBCPP_NODEBUG const _Up type;
2111};
2112
2113template <class _Tp, class _Up>
2114struct __apply_cv<_Tp, _Up, false, true>
2115{
2116    typedef volatile _Up type;
2117};
2118
2119template <class _Tp, class _Up>
2120struct __apply_cv<_Tp, _Up, true, true>
2121{
2122    typedef const volatile _Up type;
2123};
2124
2125template <class _Tp, class _Up>
2126struct __apply_cv<_Tp&, _Up, false, false>
2127{
2128    typedef _Up& type;
2129};
2130
2131template <class _Tp, class _Up>
2132struct __apply_cv<_Tp&, _Up, true, false>
2133{
2134    typedef const _Up& type;
2135};
2136
2137template <class _Tp, class _Up>
2138struct __apply_cv<_Tp&, _Up, false, true>
2139{
2140    typedef volatile _Up& type;
2141};
2142
2143template <class _Tp, class _Up>
2144struct __apply_cv<_Tp&, _Up, true, true>
2145{
2146    typedef const volatile _Up& type;
2147};
2148
2149template <class _Tp, bool = is_integral<_Tp>::value || is_enum<_Tp>::value>
2150struct __make_signed {};
2151
2152template <class _Tp>
2153struct __make_signed<_Tp, true>
2154{
2155    typedef typename __find_first<__signed_types, sizeof(_Tp)>::type type;
2156};
2157
2158template <> struct __make_signed<bool,               true> {};
2159template <> struct __make_signed<  signed short,     true> {typedef short     type;};
2160template <> struct __make_signed<unsigned short,     true> {typedef short     type;};
2161template <> struct __make_signed<  signed int,       true> {typedef int       type;};
2162template <> struct __make_signed<unsigned int,       true> {typedef int       type;};
2163template <> struct __make_signed<  signed long,      true> {typedef long      type;};
2164template <> struct __make_signed<unsigned long,      true> {typedef long      type;};
2165template <> struct __make_signed<  signed long long, true> {typedef long long type;};
2166template <> struct __make_signed<unsigned long long, true> {typedef long long type;};
2167#ifndef _LIBCPP_HAS_NO_INT128
2168template <> struct __make_signed<__int128_t,         true> {typedef __int128_t type;};
2169template <> struct __make_signed<__uint128_t,        true> {typedef __int128_t type;};
2170#endif
2171
2172template <class _Tp>
2173struct _LIBCPP_TEMPLATE_VIS make_signed
2174{
2175    typedef typename __apply_cv<_Tp, typename __make_signed<typename remove_cv<_Tp>::type>::type>::type type;
2176};
2177
2178#if _LIBCPP_STD_VER > 11
2179template <class _Tp> using make_signed_t = typename make_signed<_Tp>::type;
2180#endif
2181
2182template <class _Tp, bool = is_integral<_Tp>::value || is_enum<_Tp>::value>
2183struct __make_unsigned {};
2184
2185template <class _Tp>
2186struct __make_unsigned<_Tp, true>
2187{
2188    typedef typename __find_first<__unsigned_types, sizeof(_Tp)>::type type;
2189};
2190
2191template <> struct __make_unsigned<bool,               true> {};
2192template <> struct __make_unsigned<  signed short,     true> {typedef unsigned short     type;};
2193template <> struct __make_unsigned<unsigned short,     true> {typedef unsigned short     type;};
2194template <> struct __make_unsigned<  signed int,       true> {typedef unsigned int       type;};
2195template <> struct __make_unsigned<unsigned int,       true> {typedef unsigned int       type;};
2196template <> struct __make_unsigned<  signed long,      true> {typedef unsigned long      type;};
2197template <> struct __make_unsigned<unsigned long,      true> {typedef unsigned long      type;};
2198template <> struct __make_unsigned<  signed long long, true> {typedef unsigned long long type;};
2199template <> struct __make_unsigned<unsigned long long, true> {typedef unsigned long long type;};
2200#ifndef _LIBCPP_HAS_NO_INT128
2201template <> struct __make_unsigned<__int128_t,         true> {typedef __uint128_t        type;};
2202template <> struct __make_unsigned<__uint128_t,        true> {typedef __uint128_t        type;};
2203#endif
2204
2205template <class _Tp>
2206struct _LIBCPP_TEMPLATE_VIS make_unsigned
2207{
2208    typedef typename __apply_cv<_Tp, typename __make_unsigned<typename remove_cv<_Tp>::type>::type>::type type;
2209};
2210
2211#if _LIBCPP_STD_VER > 11
2212template <class _Tp> using make_unsigned_t = typename make_unsigned<_Tp>::type;
2213#endif
2214
2215#ifndef _LIBCPP_CXX03_LANG
2216template <class _Tp>
2217_LIBCPP_HIDE_FROM_ABI constexpr
2218typename make_unsigned<_Tp>::type __to_unsigned_like(_Tp __x) noexcept {
2219    return static_cast<typename make_unsigned<_Tp>::type>(__x);
2220}
2221#endif
2222
2223#if _LIBCPP_STD_VER > 14
2224template <class...> using void_t = void;
2225#endif
2226
2227#if _LIBCPP_STD_VER > 17
2228// Let COND_RES(X, Y) be:
2229template <class _Tp, class _Up>
2230using __cond_type = decltype(false ? declval<_Tp>() : declval<_Up>());
2231
2232template <class _Tp, class _Up, class = void>
2233struct __common_type3 {};
2234
2235// sub-bullet 4 - "if COND_RES(CREF(D1), CREF(D2)) denotes a type..."
2236template <class _Tp, class _Up>
2237struct __common_type3<_Tp, _Up, void_t<__cond_type<const _Tp&, const _Up&>>>
2238{
2239    using type = remove_cvref_t<__cond_type<const _Tp&, const _Up&>>;
2240};
2241
2242template <class _Tp, class _Up, class = void>
2243struct __common_type2_imp : __common_type3<_Tp, _Up> {};
2244#else
2245template <class _Tp, class _Up, class = void>
2246struct __common_type2_imp {};
2247#endif
2248
2249// sub-bullet 3 - "if decay_t<decltype(false ? declval<D1>() : declval<D2>())> ..."
2250template <class _Tp, class _Up>
2251struct __common_type2_imp<_Tp, _Up,
2252                          typename __void_t<decltype(
2253                                            true ? declval<_Tp>() : declval<_Up>()
2254                                            )>::type>
2255{
2256  typedef _LIBCPP_NODEBUG typename decay<decltype(
2257                         true ? declval<_Tp>() : declval<_Up>()
2258                         )>::type type;
2259};
2260
2261template <class, class = void>
2262struct __common_type_impl {};
2263
2264// Clang provides variadic templates in C++03 as an extension.
2265#if !defined(_LIBCPP_CXX03_LANG) || defined(__clang__)
2266# define _LIBCPP_OPTIONAL_PACK(...) , __VA_ARGS__
2267template <class... _Tp>
2268struct __common_types;
2269template <class... _Tp>
2270struct _LIBCPP_TEMPLATE_VIS common_type;
2271#else
2272# define _LIBCPP_OPTIONAL_PACK(...)
2273struct __no_arg;
2274template <class _Tp, class _Up, class = __no_arg>
2275struct __common_types;
2276template <class _Tp = __no_arg, class _Up = __no_arg, class _Vp = __no_arg,
2277          class _Unused = __no_arg>
2278struct common_type {
2279  static_assert(sizeof(_Unused) == 0,
2280                "common_type accepts at most 3 arguments in C++03");
2281};
2282#endif // _LIBCPP_CXX03_LANG
2283
2284template <class _Tp, class _Up>
2285struct __common_type_impl<
2286    __common_types<_Tp, _Up>,
2287    typename __void_t<typename common_type<_Tp, _Up>::type>::type>
2288{
2289  typedef typename common_type<_Tp, _Up>::type type;
2290};
2291
2292template <class _Tp, class _Up, class _Vp _LIBCPP_OPTIONAL_PACK(class... _Rest)>
2293struct __common_type_impl<
2294    __common_types<_Tp, _Up, _Vp _LIBCPP_OPTIONAL_PACK(_Rest...)>,
2295    typename __void_t<typename common_type<_Tp, _Up>::type>::type>
2296    : __common_type_impl<__common_types<typename common_type<_Tp, _Up>::type,
2297                                        _Vp _LIBCPP_OPTIONAL_PACK(_Rest...)> > {
2298};
2299
2300// bullet 1 - sizeof...(Tp) == 0
2301
2302template <>
2303struct _LIBCPP_TEMPLATE_VIS common_type<> {};
2304
2305// bullet 2 - sizeof...(Tp) == 1
2306
2307template <class _Tp>
2308struct _LIBCPP_TEMPLATE_VIS common_type<_Tp>
2309    : public common_type<_Tp, _Tp> {};
2310
2311// bullet 3 - sizeof...(Tp) == 2
2312
2313// sub-bullet 1 - "If is_same_v<T1, D1> is false or ..."
2314template <class _Tp, class _Up>
2315struct _LIBCPP_TEMPLATE_VIS common_type<_Tp, _Up>
2316    : conditional<
2317        _IsSame<_Tp, typename decay<_Tp>::type>::value && _IsSame<_Up, typename decay<_Up>::type>::value,
2318        __common_type2_imp<_Tp, _Up>,
2319        common_type<typename decay<_Tp>::type, typename decay<_Up>::type>
2320    >::type
2321{};
2322
2323// bullet 4 - sizeof...(Tp) > 2
2324
2325template <class _Tp, class _Up, class _Vp _LIBCPP_OPTIONAL_PACK(class... _Rest)>
2326struct _LIBCPP_TEMPLATE_VIS
2327    common_type<_Tp, _Up, _Vp _LIBCPP_OPTIONAL_PACK(_Rest...)>
2328    : __common_type_impl<
2329          __common_types<_Tp, _Up, _Vp _LIBCPP_OPTIONAL_PACK(_Rest...)> > {};
2330
2331#undef _LIBCPP_OPTIONAL_PACK
2332
2333#if _LIBCPP_STD_VER > 11
2334template <class ..._Tp> using common_type_t = typename common_type<_Tp...>::type;
2335#endif
2336
2337#if _LIBCPP_STD_VER > 11
2338// Let COPYCV(FROM, TO) be an alias for type TO with the addition of FROM's
2339// top-level cv-qualifiers.
2340template <class _From, class _To>
2341struct __copy_cv
2342{
2343    using type = _To;
2344};
2345
2346template <class _From, class _To>
2347struct __copy_cv<const _From, _To>
2348{
2349    using type = add_const_t<_To>;
2350};
2351
2352template <class _From, class _To>
2353struct __copy_cv<volatile _From, _To>
2354{
2355    using type = add_volatile_t<_To>;
2356};
2357
2358template <class _From, class _To>
2359struct __copy_cv<const volatile _From, _To>
2360{
2361    using type = add_cv_t<_To>;
2362};
2363
2364template <class _From, class _To>
2365using __copy_cv_t = typename __copy_cv<_From, _To>::type;
2366
2367template <class _From, class _To>
2368struct __copy_cvref
2369{
2370    using type = __copy_cv_t<_From, _To>;
2371};
2372
2373template <class _From, class _To>
2374struct __copy_cvref<_From&, _To>
2375{
2376    using type = add_lvalue_reference_t<__copy_cv_t<_From, _To>>;
2377};
2378
2379template <class _From, class _To>
2380struct __copy_cvref<_From&&, _To>
2381{
2382    using type = add_rvalue_reference_t<__copy_cv_t<_From, _To>>;
2383};
2384
2385template <class _From, class _To>
2386using __copy_cvref_t = typename __copy_cvref<_From, _To>::type;
2387
2388#endif // _LIBCPP_STD_VER > 11
2389
2390// common_reference
2391#if _LIBCPP_STD_VER > 17
2392// Let COND_RES(X, Y) be:
2393template <class _Xp, class _Yp>
2394using __cond_res =
2395    decltype(false ? declval<_Xp(&)()>()() : declval<_Yp(&)()>()());
2396
2397// Let `XREF(A)` denote a unary alias template `T` such that `T<U>` denotes the same type as `U`
2398// with the addition of `A`'s cv and reference qualifiers, for a non-reference cv-unqualified type
2399// `U`.
2400// [Note: `XREF(A)` is `__xref<A>::template __apply`]
2401template <class _Tp>
2402struct __xref {
2403  template<class _Up>
2404  using __apply = __copy_cvref_t<_Tp, _Up>;
2405};
2406
2407// Given types A and B, let X be remove_reference_t<A>, let Y be remove_reference_t<B>,
2408// and let COMMON-REF(A, B) be:
2409template<class _Ap, class _Bp, class _Xp = remove_reference_t<_Ap>, class _Yp = remove_reference_t<_Bp>>
2410struct __common_ref;
2411
2412template<class _Xp, class _Yp>
2413using __common_ref_t = typename __common_ref<_Xp, _Yp>::__type;
2414
2415template<class _Xp, class _Yp>
2416using __cv_cond_res = __cond_res<__copy_cv_t<_Xp, _Yp>&, __copy_cv_t<_Yp, _Xp>&>;
2417
2418
2419//    If A and B are both lvalue reference types, COMMON-REF(A, B) is
2420//    COND-RES(COPYCV(X, Y)&, COPYCV(Y, X)&) if that type exists and is a reference type.
2421template<class _Ap, class _Bp, class _Xp, class _Yp>
2422requires requires { typename __cv_cond_res<_Xp, _Yp>; } && is_reference_v<__cv_cond_res<_Xp, _Yp>>
2423struct __common_ref<_Ap&, _Bp&, _Xp, _Yp>
2424{
2425    using __type = __cv_cond_res<_Xp, _Yp>;
2426};
2427
2428//    Otherwise, let C be remove_reference_t<COMMON-REF(X&, Y&)>&&. ...
2429template <class _Xp, class _Yp>
2430using __common_ref_C = remove_reference_t<__common_ref_t<_Xp&, _Yp&>>&&;
2431
2432
2433//    .... If A and B are both rvalue reference types, C is well-formed, and
2434//    is_convertible_v<A, C> && is_convertible_v<B, C> is true, then COMMON-REF(A, B) is C.
2435template<class _Ap, class _Bp, class _Xp, class _Yp>
2436requires
2437  requires { typename __common_ref_C<_Xp, _Yp>; } &&
2438  is_convertible_v<_Ap&&, __common_ref_C<_Xp, _Yp>> &&
2439  is_convertible_v<_Bp&&, __common_ref_C<_Xp, _Yp>>
2440struct __common_ref<_Ap&&, _Bp&&, _Xp, _Yp>
2441{
2442    using __type = __common_ref_C<_Xp, _Yp>;
2443};
2444
2445//    Otherwise, let D be COMMON-REF(const X&, Y&). ...
2446template <class _Tp, class _Up>
2447using __common_ref_D = __common_ref_t<const _Tp&, _Up&>;
2448
2449//    ... If A is an rvalue reference and B is an lvalue reference and D is well-formed and
2450//    is_convertible_v<A, D> is true, then COMMON-REF(A, B) is D.
2451template<class _Ap, class _Bp, class _Xp, class _Yp>
2452requires requires { typename __common_ref_D<_Xp, _Yp>; } &&
2453         is_convertible_v<_Ap&&, __common_ref_D<_Xp, _Yp>>
2454struct __common_ref<_Ap&&, _Bp&, _Xp, _Yp>
2455{
2456    using __type = __common_ref_D<_Xp, _Yp>;
2457};
2458
2459//    Otherwise, if A is an lvalue reference and B is an rvalue reference, then
2460//    COMMON-REF(A, B) is COMMON-REF(B, A).
2461template<class _Ap, class _Bp, class _Xp, class _Yp>
2462struct __common_ref<_Ap&, _Bp&&, _Xp, _Yp> : __common_ref<_Bp&&, _Ap&> {};
2463
2464//    Otherwise, COMMON-REF(A, B) is ill-formed.
2465template<class _Ap, class _Bp, class _Xp, class _Yp>
2466struct __common_ref {};
2467
2468// Note C: For the common_reference trait applied to a parameter pack [...]
2469
2470template <class...>
2471struct common_reference;
2472
2473template <class... _Types>
2474using common_reference_t = typename common_reference<_Types...>::type;
2475
2476// bullet 1 - sizeof...(T) == 0
2477template<>
2478struct common_reference<> {};
2479
2480// bullet 2 - sizeof...(T) == 1
2481template <class _Tp>
2482struct common_reference<_Tp>
2483{
2484    using type = _Tp;
2485};
2486
2487// bullet 3 - sizeof...(T) == 2
2488template <class _Tp, class _Up> struct __common_reference_sub_bullet3;
2489template <class _Tp, class _Up> struct __common_reference_sub_bullet2 : __common_reference_sub_bullet3<_Tp, _Up> {};
2490template <class _Tp, class _Up> struct __common_reference_sub_bullet1 : __common_reference_sub_bullet2<_Tp, _Up> {};
2491
2492// sub-bullet 1 - If T1 and T2 are reference types and COMMON-REF(T1, T2) is well-formed, then
2493// the member typedef `type` denotes that type.
2494template <class _Tp, class _Up> struct common_reference<_Tp, _Up> : __common_reference_sub_bullet1<_Tp, _Up> {};
2495
2496template <class _Tp, class _Up>
2497requires is_reference_v<_Tp> && is_reference_v<_Up> && requires { typename __common_ref_t<_Tp, _Up>; }
2498struct __common_reference_sub_bullet1<_Tp, _Up>
2499{
2500    using type = __common_ref_t<_Tp, _Up>;
2501};
2502
2503// sub-bullet 2 - Otherwise, if basic_common_reference<remove_cvref_t<T1>, remove_cvref_t<T2>, XREF(T1), XREF(T2)>::type
2504// is well-formed, then the member typedef `type` denotes that type.
2505template <class, class, template <class> class, template <class> class> struct basic_common_reference {};
2506
2507template <class _Tp, class _Up>
2508using __basic_common_reference_t = typename basic_common_reference<
2509    remove_cvref_t<_Tp>, remove_cvref_t<_Up>,
2510    __xref<_Tp>::template __apply, __xref<_Up>::template __apply>::type;
2511
2512template <class _Tp, class _Up>
2513requires requires { typename __basic_common_reference_t<_Tp, _Up>; }
2514struct __common_reference_sub_bullet2<_Tp, _Up>
2515{
2516    using type = __basic_common_reference_t<_Tp, _Up>;
2517};
2518
2519// sub-bullet 3 - Otherwise, if COND-RES(T1, T2) is well-formed,
2520// then the member typedef `type` denotes that type.
2521template <class _Tp, class _Up>
2522requires requires { typename __cond_res<_Tp, _Up>; }
2523struct __common_reference_sub_bullet3<_Tp, _Up>
2524{
2525    using type = __cond_res<_Tp, _Up>;
2526};
2527
2528
2529// sub-bullet 4 & 5 - Otherwise, if common_type_t<T1, T2> is well-formed,
2530//                    then the member typedef `type` denotes that type.
2531//                  - Otherwise, there shall be no member `type`.
2532template <class _Tp, class _Up> struct __common_reference_sub_bullet3 : common_type<_Tp, _Up> {};
2533
2534// bullet 4 - If there is such a type `C`, the member typedef type shall denote the same type, if
2535//            any, as `common_reference_t<C, Rest...>`.
2536template <class _Tp, class _Up, class _Vp, class... _Rest>
2537requires requires { typename common_reference_t<_Tp, _Up>; }
2538struct common_reference<_Tp, _Up, _Vp, _Rest...>
2539    : common_reference<common_reference_t<_Tp, _Up>, _Vp, _Rest...>
2540{};
2541
2542// bullet 5 - Otherwise, there shall be no member `type`.
2543template <class...> struct common_reference {};
2544
2545#endif // _LIBCPP_STD_VER > 17
2546
2547// is_assignable
2548
2549template<typename, typename _Tp> struct __select_2nd { typedef _LIBCPP_NODEBUG _Tp type; };
2550
2551#if __has_keyword(__is_assignable)
2552
2553template<class _Tp, class _Up>
2554struct _LIBCPP_TEMPLATE_VIS is_assignable : _BoolConstant<__is_assignable(_Tp, _Up)> { };
2555
2556#if _LIBCPP_STD_VER > 14
2557template <class _Tp, class _Arg>
2558inline constexpr bool is_assignable_v = __is_assignable(_Tp, _Arg);
2559#endif
2560
2561#else // __has_keyword(__is_assignable)
2562
2563template <class _Tp, class _Arg>
2564typename __select_2nd<decltype((declval<_Tp>() = declval<_Arg>())), true_type>::type
2565__is_assignable_test(int);
2566
2567template <class, class>
2568false_type __is_assignable_test(...);
2569
2570
2571template <class _Tp, class _Arg, bool = is_void<_Tp>::value || is_void<_Arg>::value>
2572struct __is_assignable_imp
2573    : public decltype((_VSTD::__is_assignable_test<_Tp, _Arg>(0))) {};
2574
2575template <class _Tp, class _Arg>
2576struct __is_assignable_imp<_Tp, _Arg, true>
2577    : public false_type
2578{
2579};
2580
2581template <class _Tp, class _Arg>
2582struct is_assignable
2583    : public __is_assignable_imp<_Tp, _Arg> {};
2584
2585#if _LIBCPP_STD_VER > 14
2586template <class _Tp, class _Arg>
2587inline constexpr bool is_assignable_v = is_assignable<_Tp, _Arg>::value;
2588#endif
2589
2590#endif // __has_keyword(__is_assignable)
2591
2592// is_copy_assignable
2593
2594template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_copy_assignable
2595    : public is_assignable<typename add_lvalue_reference<_Tp>::type,
2596                  typename add_lvalue_reference<typename add_const<_Tp>::type>::type> {};
2597
2598#if _LIBCPP_STD_VER > 14
2599template <class _Tp>
2600inline constexpr bool is_copy_assignable_v = is_copy_assignable<_Tp>::value;
2601#endif
2602
2603// is_move_assignable
2604
2605template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_move_assignable
2606    : public is_assignable<typename add_lvalue_reference<_Tp>::type,
2607                           typename add_rvalue_reference<_Tp>::type> {};
2608
2609#if _LIBCPP_STD_VER > 14
2610template <class _Tp>
2611inline constexpr bool is_move_assignable_v = is_move_assignable<_Tp>::value;
2612#endif
2613
2614// is_destructible
2615
2616#if __has_keyword(__is_destructible)
2617
2618template<class _Tp>
2619struct _LIBCPP_TEMPLATE_VIS is_destructible : _BoolConstant<__is_destructible(_Tp)> { };
2620
2621#if _LIBCPP_STD_VER > 14
2622template <class _Tp>
2623inline constexpr bool is_destructible_v = __is_destructible(_Tp);
2624#endif
2625
2626#else // __has_keyword(__is_destructible)
2627
2628//  if it's a reference, return true
2629//  if it's a function, return false
2630//  if it's   void,     return false
2631//  if it's an array of unknown bound, return false
2632//  Otherwise, return "declval<_Up&>().~_Up()" is well-formed
2633//    where _Up is remove_all_extents<_Tp>::type
2634
2635template <class>
2636struct __is_destructible_apply { typedef int type; };
2637
2638template <typename _Tp>
2639struct __is_destructor_wellformed {
2640    template <typename _Tp1>
2641    static char  __test (
2642        typename __is_destructible_apply<decltype(declval<_Tp1&>().~_Tp1())>::type
2643    );
2644
2645    template <typename _Tp1>
2646    static __two __test (...);
2647
2648    static const bool value = sizeof(__test<_Tp>(12)) == sizeof(char);
2649};
2650
2651template <class _Tp, bool>
2652struct __destructible_imp;
2653
2654template <class _Tp>
2655struct __destructible_imp<_Tp, false>
2656   : public integral_constant<bool,
2657        __is_destructor_wellformed<typename remove_all_extents<_Tp>::type>::value> {};
2658
2659template <class _Tp>
2660struct __destructible_imp<_Tp, true>
2661    : public true_type {};
2662
2663template <class _Tp, bool>
2664struct __destructible_false;
2665
2666template <class _Tp>
2667struct __destructible_false<_Tp, false> : public __destructible_imp<_Tp, is_reference<_Tp>::value> {};
2668
2669template <class _Tp>
2670struct __destructible_false<_Tp, true> : public false_type {};
2671
2672template <class _Tp>
2673struct is_destructible
2674    : public __destructible_false<_Tp, is_function<_Tp>::value> {};
2675
2676template <class _Tp>
2677struct is_destructible<_Tp[]>
2678    : public false_type {};
2679
2680template <>
2681struct is_destructible<void>
2682    : public false_type {};
2683
2684#if _LIBCPP_STD_VER > 14
2685template <class _Tp>
2686inline constexpr bool is_destructible_v = is_destructible<_Tp>::value;
2687#endif
2688
2689#endif // __has_keyword(__is_destructible)
2690
2691template <class _MP, bool _IsMemberFunctionPtr, bool _IsMemberObjectPtr>
2692struct __member_pointer_traits_imp
2693{
2694};
2695
2696template <class _Rp, class _Class, class ..._Param>
2697struct __member_pointer_traits_imp<_Rp (_Class::*)(_Param...), true, false>
2698{
2699    typedef _Class _ClassType;
2700    typedef _Rp _ReturnType;
2701    typedef _Rp (_FnType) (_Param...);
2702};
2703
2704template <class _Rp, class _Class, class ..._Param>
2705struct __member_pointer_traits_imp<_Rp (_Class::*)(_Param..., ...), true, false>
2706{
2707    typedef _Class _ClassType;
2708    typedef _Rp _ReturnType;
2709    typedef _Rp (_FnType) (_Param..., ...);
2710};
2711
2712template <class _Rp, class _Class, class ..._Param>
2713struct __member_pointer_traits_imp<_Rp (_Class::*)(_Param...) const, true, false>
2714{
2715    typedef _Class const _ClassType;
2716    typedef _Rp _ReturnType;
2717    typedef _Rp (_FnType) (_Param...);
2718};
2719
2720template <class _Rp, class _Class, class ..._Param>
2721struct __member_pointer_traits_imp<_Rp (_Class::*)(_Param..., ...) const, true, false>
2722{
2723    typedef _Class const _ClassType;
2724    typedef _Rp _ReturnType;
2725    typedef _Rp (_FnType) (_Param..., ...);
2726};
2727
2728template <class _Rp, class _Class, class ..._Param>
2729struct __member_pointer_traits_imp<_Rp (_Class::*)(_Param...) volatile, true, false>
2730{
2731    typedef _Class volatile _ClassType;
2732    typedef _Rp _ReturnType;
2733    typedef _Rp (_FnType) (_Param...);
2734};
2735
2736template <class _Rp, class _Class, class ..._Param>
2737struct __member_pointer_traits_imp<_Rp (_Class::*)(_Param..., ...) volatile, true, false>
2738{
2739    typedef _Class volatile _ClassType;
2740    typedef _Rp _ReturnType;
2741    typedef _Rp (_FnType) (_Param..., ...);
2742};
2743
2744template <class _Rp, class _Class, class ..._Param>
2745struct __member_pointer_traits_imp<_Rp (_Class::*)(_Param...) const volatile, true, false>
2746{
2747    typedef _Class const volatile _ClassType;
2748    typedef _Rp _ReturnType;
2749    typedef _Rp (_FnType) (_Param...);
2750};
2751
2752template <class _Rp, class _Class, class ..._Param>
2753struct __member_pointer_traits_imp<_Rp (_Class::*)(_Param..., ...) const volatile, true, false>
2754{
2755    typedef _Class const volatile _ClassType;
2756    typedef _Rp _ReturnType;
2757    typedef _Rp (_FnType) (_Param..., ...);
2758};
2759
2760#if __has_feature(cxx_reference_qualified_functions) || defined(_LIBCPP_COMPILER_GCC)
2761
2762template <class _Rp, class _Class, class ..._Param>
2763struct __member_pointer_traits_imp<_Rp (_Class::*)(_Param...) &, true, false>
2764{
2765    typedef _Class& _ClassType;
2766    typedef _Rp _ReturnType;
2767    typedef _Rp (_FnType) (_Param...);
2768};
2769
2770template <class _Rp, class _Class, class ..._Param>
2771struct __member_pointer_traits_imp<_Rp (_Class::*)(_Param..., ...) &, true, false>
2772{
2773    typedef _Class& _ClassType;
2774    typedef _Rp _ReturnType;
2775    typedef _Rp (_FnType) (_Param..., ...);
2776};
2777
2778template <class _Rp, class _Class, class ..._Param>
2779struct __member_pointer_traits_imp<_Rp (_Class::*)(_Param...) const&, true, false>
2780{
2781    typedef _Class const& _ClassType;
2782    typedef _Rp _ReturnType;
2783    typedef _Rp (_FnType) (_Param...);
2784};
2785
2786template <class _Rp, class _Class, class ..._Param>
2787struct __member_pointer_traits_imp<_Rp (_Class::*)(_Param..., ...) const&, true, false>
2788{
2789    typedef _Class const& _ClassType;
2790    typedef _Rp _ReturnType;
2791    typedef _Rp (_FnType) (_Param..., ...);
2792};
2793
2794template <class _Rp, class _Class, class ..._Param>
2795struct __member_pointer_traits_imp<_Rp (_Class::*)(_Param...) volatile&, true, false>
2796{
2797    typedef _Class volatile& _ClassType;
2798    typedef _Rp _ReturnType;
2799    typedef _Rp (_FnType) (_Param...);
2800};
2801
2802template <class _Rp, class _Class, class ..._Param>
2803struct __member_pointer_traits_imp<_Rp (_Class::*)(_Param..., ...) volatile&, true, false>
2804{
2805    typedef _Class volatile& _ClassType;
2806    typedef _Rp _ReturnType;
2807    typedef _Rp (_FnType) (_Param..., ...);
2808};
2809
2810template <class _Rp, class _Class, class ..._Param>
2811struct __member_pointer_traits_imp<_Rp (_Class::*)(_Param...) const volatile&, true, false>
2812{
2813    typedef _Class const volatile& _ClassType;
2814    typedef _Rp _ReturnType;
2815    typedef _Rp (_FnType) (_Param...);
2816};
2817
2818template <class _Rp, class _Class, class ..._Param>
2819struct __member_pointer_traits_imp<_Rp (_Class::*)(_Param..., ...) const volatile&, true, false>
2820{
2821    typedef _Class const volatile& _ClassType;
2822    typedef _Rp _ReturnType;
2823    typedef _Rp (_FnType) (_Param..., ...);
2824};
2825
2826template <class _Rp, class _Class, class ..._Param>
2827struct __member_pointer_traits_imp<_Rp (_Class::*)(_Param...) &&, true, false>
2828{
2829    typedef _Class&& _ClassType;
2830    typedef _Rp _ReturnType;
2831    typedef _Rp (_FnType) (_Param...);
2832};
2833
2834template <class _Rp, class _Class, class ..._Param>
2835struct __member_pointer_traits_imp<_Rp (_Class::*)(_Param..., ...) &&, true, false>
2836{
2837    typedef _Class&& _ClassType;
2838    typedef _Rp _ReturnType;
2839    typedef _Rp (_FnType) (_Param..., ...);
2840};
2841
2842template <class _Rp, class _Class, class ..._Param>
2843struct __member_pointer_traits_imp<_Rp (_Class::*)(_Param...) const&&, true, false>
2844{
2845    typedef _Class const&& _ClassType;
2846    typedef _Rp _ReturnType;
2847    typedef _Rp (_FnType) (_Param...);
2848};
2849
2850template <class _Rp, class _Class, class ..._Param>
2851struct __member_pointer_traits_imp<_Rp (_Class::*)(_Param..., ...) const&&, true, false>
2852{
2853    typedef _Class const&& _ClassType;
2854    typedef _Rp _ReturnType;
2855    typedef _Rp (_FnType) (_Param..., ...);
2856};
2857
2858template <class _Rp, class _Class, class ..._Param>
2859struct __member_pointer_traits_imp<_Rp (_Class::*)(_Param...) volatile&&, true, false>
2860{
2861    typedef _Class volatile&& _ClassType;
2862    typedef _Rp _ReturnType;
2863    typedef _Rp (_FnType) (_Param...);
2864};
2865
2866template <class _Rp, class _Class, class ..._Param>
2867struct __member_pointer_traits_imp<_Rp (_Class::*)(_Param..., ...) volatile&&, true, false>
2868{
2869    typedef _Class volatile&& _ClassType;
2870    typedef _Rp _ReturnType;
2871    typedef _Rp (_FnType) (_Param..., ...);
2872};
2873
2874template <class _Rp, class _Class, class ..._Param>
2875struct __member_pointer_traits_imp<_Rp (_Class::*)(_Param...) const volatile&&, true, false>
2876{
2877    typedef _Class const volatile&& _ClassType;
2878    typedef _Rp _ReturnType;
2879    typedef _Rp (_FnType) (_Param...);
2880};
2881
2882template <class _Rp, class _Class, class ..._Param>
2883struct __member_pointer_traits_imp<_Rp (_Class::*)(_Param..., ...) const volatile&&, true, false>
2884{
2885    typedef _Class const volatile&& _ClassType;
2886    typedef _Rp _ReturnType;
2887    typedef _Rp (_FnType) (_Param..., ...);
2888};
2889
2890#endif // __has_feature(cxx_reference_qualified_functions) || defined(_LIBCPP_COMPILER_GCC)
2891
2892
2893template <class _Rp, class _Class>
2894struct __member_pointer_traits_imp<_Rp _Class::*, false, true>
2895{
2896    typedef _Class _ClassType;
2897    typedef _Rp _ReturnType;
2898};
2899
2900template <class _MP>
2901struct __member_pointer_traits
2902    : public __member_pointer_traits_imp<typename remove_cv<_MP>::type,
2903                    is_member_function_pointer<_MP>::value,
2904                    is_member_object_pointer<_MP>::value>
2905{
2906//     typedef ... _ClassType;
2907//     typedef ... _ReturnType;
2908//     typedef ... _FnType;
2909};
2910
2911
2912template <class _DecayedFp>
2913struct __member_pointer_class_type {};
2914
2915template <class _Ret, class _ClassType>
2916struct __member_pointer_class_type<_Ret _ClassType::*> {
2917  typedef _ClassType type;
2918};
2919
2920// template <class T, class... Args> struct is_constructible;
2921
2922template <class _Tp, class ..._Args>
2923struct _LIBCPP_TEMPLATE_VIS is_constructible
2924    : public integral_constant<bool, __is_constructible(_Tp, _Args...)>
2925{ };
2926
2927#if _LIBCPP_STD_VER > 14
2928template <class _Tp, class ..._Args>
2929inline constexpr bool is_constructible_v = is_constructible<_Tp, _Args...>::value;
2930#endif
2931
2932// is_default_constructible
2933
2934template <class _Tp>
2935struct _LIBCPP_TEMPLATE_VIS is_default_constructible
2936    : public is_constructible<_Tp>
2937    {};
2938
2939#if _LIBCPP_STD_VER > 14
2940template <class _Tp>
2941inline constexpr bool is_default_constructible_v = is_default_constructible<_Tp>::value;
2942#endif
2943
2944#ifndef _LIBCPP_CXX03_LANG
2945// First of all, we can't implement this check in C++03 mode because the {}
2946// default initialization syntax isn't valid.
2947// Second, we implement the trait in a funny manner with two defaulted template
2948// arguments to workaround Clang's PR43454.
2949template <class _Tp>
2950void __test_implicit_default_constructible(_Tp);
2951
2952template <class _Tp, class = void, class = typename is_default_constructible<_Tp>::type>
2953struct __is_implicitly_default_constructible
2954    : false_type
2955{ };
2956
2957template <class _Tp>
2958struct __is_implicitly_default_constructible<_Tp, decltype(__test_implicit_default_constructible<_Tp const&>({})), true_type>
2959    : true_type
2960{ };
2961
2962template <class _Tp>
2963struct __is_implicitly_default_constructible<_Tp, decltype(__test_implicit_default_constructible<_Tp const&>({})), false_type>
2964    : false_type
2965{ };
2966#endif // !C++03
2967
2968// is_copy_constructible
2969
2970template <class _Tp>
2971struct _LIBCPP_TEMPLATE_VIS is_copy_constructible
2972    : public is_constructible<_Tp,
2973                  typename add_lvalue_reference<typename add_const<_Tp>::type>::type> {};
2974
2975#if _LIBCPP_STD_VER > 14
2976template <class _Tp>
2977inline constexpr bool is_copy_constructible_v = is_copy_constructible<_Tp>::value;
2978#endif
2979
2980// is_move_constructible
2981
2982template <class _Tp>
2983struct _LIBCPP_TEMPLATE_VIS is_move_constructible
2984    : public is_constructible<_Tp, typename add_rvalue_reference<_Tp>::type>
2985    {};
2986
2987#if _LIBCPP_STD_VER > 14
2988template <class _Tp>
2989inline constexpr bool is_move_constructible_v = is_move_constructible<_Tp>::value;
2990#endif
2991
2992// is_trivially_constructible
2993
2994template <class _Tp, class... _Args>
2995struct _LIBCPP_TEMPLATE_VIS is_trivially_constructible
2996    : integral_constant<bool, __is_trivially_constructible(_Tp, _Args...)>
2997{
2998};
2999
3000#if _LIBCPP_STD_VER > 14
3001template <class _Tp, class... _Args>
3002inline constexpr bool is_trivially_constructible_v = is_trivially_constructible<_Tp, _Args...>::value;
3003#endif
3004
3005// is_trivially_default_constructible
3006
3007template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_trivially_default_constructible
3008    : public is_trivially_constructible<_Tp>
3009    {};
3010
3011#if _LIBCPP_STD_VER > 14
3012template <class _Tp>
3013inline constexpr bool is_trivially_default_constructible_v = is_trivially_default_constructible<_Tp>::value;
3014#endif
3015
3016// is_trivially_copy_constructible
3017
3018template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_trivially_copy_constructible
3019    : public is_trivially_constructible<_Tp, typename add_lvalue_reference<const _Tp>::type>
3020    {};
3021
3022#if _LIBCPP_STD_VER > 14
3023template <class _Tp>
3024inline constexpr bool is_trivially_copy_constructible_v = is_trivially_copy_constructible<_Tp>::value;
3025#endif
3026
3027// is_trivially_move_constructible
3028
3029template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_trivially_move_constructible
3030    : public is_trivially_constructible<_Tp, typename add_rvalue_reference<_Tp>::type>
3031    {};
3032
3033#if _LIBCPP_STD_VER > 14
3034template <class _Tp>
3035inline constexpr bool is_trivially_move_constructible_v = is_trivially_move_constructible<_Tp>::value;
3036#endif
3037
3038// is_trivially_assignable
3039
3040template <class _Tp, class _Arg>
3041struct is_trivially_assignable
3042    : integral_constant<bool, __is_trivially_assignable(_Tp, _Arg)>
3043{ };
3044
3045#if _LIBCPP_STD_VER > 14
3046template <class _Tp, class _Arg>
3047inline constexpr bool is_trivially_assignable_v = is_trivially_assignable<_Tp, _Arg>::value;
3048#endif
3049
3050// is_trivially_copy_assignable
3051
3052template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_trivially_copy_assignable
3053    : public is_trivially_assignable<typename add_lvalue_reference<_Tp>::type,
3054                  typename add_lvalue_reference<typename add_const<_Tp>::type>::type> {};
3055
3056#if _LIBCPP_STD_VER > 14
3057template <class _Tp>
3058inline constexpr bool is_trivially_copy_assignable_v = is_trivially_copy_assignable<_Tp>::value;
3059#endif
3060
3061// is_trivially_move_assignable
3062
3063template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_trivially_move_assignable
3064    : public is_trivially_assignable<typename add_lvalue_reference<_Tp>::type,
3065                                     typename add_rvalue_reference<_Tp>::type>
3066    {};
3067
3068#if _LIBCPP_STD_VER > 14
3069template <class _Tp>
3070inline constexpr bool is_trivially_move_assignable_v = is_trivially_move_assignable<_Tp>::value;
3071#endif
3072
3073// is_trivially_destructible
3074
3075#if __has_keyword(__is_trivially_destructible)
3076
3077template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_trivially_destructible
3078    : public integral_constant<bool, __is_trivially_destructible(_Tp)> {};
3079
3080#elif __has_feature(has_trivial_destructor) || defined(_LIBCPP_COMPILER_GCC)
3081
3082template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_trivially_destructible
3083    : public integral_constant<bool, is_destructible<_Tp>::value && __has_trivial_destructor(_Tp)> {};
3084
3085#else
3086
3087template <class _Tp> struct __libcpp_trivial_destructor
3088    : public integral_constant<bool, is_scalar<_Tp>::value ||
3089                                     is_reference<_Tp>::value> {};
3090
3091template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_trivially_destructible
3092    : public __libcpp_trivial_destructor<typename remove_all_extents<_Tp>::type> {};
3093
3094template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_trivially_destructible<_Tp[]>
3095    : public false_type {};
3096
3097#endif
3098
3099#if _LIBCPP_STD_VER > 14
3100template <class _Tp>
3101inline constexpr bool is_trivially_destructible_v = is_trivially_destructible<_Tp>::value;
3102#endif
3103
3104// is_nothrow_constructible
3105
3106#if __has_keyword(__is_nothrow_constructible)
3107
3108template <class _Tp, class... _Args>
3109struct _LIBCPP_TEMPLATE_VIS is_nothrow_constructible
3110    : public integral_constant<bool, __is_nothrow_constructible(_Tp, _Args...)> {};
3111
3112#else
3113
3114template <bool, bool, class _Tp, class... _Args> struct __libcpp_is_nothrow_constructible;
3115
3116template <class _Tp, class... _Args>
3117struct __libcpp_is_nothrow_constructible</*is constructible*/true, /*is reference*/false, _Tp, _Args...>
3118    : public integral_constant<bool, noexcept(_Tp(declval<_Args>()...))>
3119{
3120};
3121
3122template <class _Tp>
3123void __implicit_conversion_to(_Tp) noexcept { }
3124
3125template <class _Tp, class _Arg>
3126struct __libcpp_is_nothrow_constructible</*is constructible*/true, /*is reference*/true, _Tp, _Arg>
3127    : public integral_constant<bool, noexcept(_VSTD::__implicit_conversion_to<_Tp>(declval<_Arg>()))>
3128{
3129};
3130
3131template <class _Tp, bool _IsReference, class... _Args>
3132struct __libcpp_is_nothrow_constructible</*is constructible*/false, _IsReference, _Tp, _Args...>
3133    : public false_type
3134{
3135};
3136
3137template <class _Tp, class... _Args>
3138struct _LIBCPP_TEMPLATE_VIS is_nothrow_constructible
3139    : __libcpp_is_nothrow_constructible<is_constructible<_Tp, _Args...>::value, is_reference<_Tp>::value, _Tp, _Args...>
3140{
3141};
3142
3143template <class _Tp, size_t _Ns>
3144struct _LIBCPP_TEMPLATE_VIS is_nothrow_constructible<_Tp[_Ns]>
3145    : __libcpp_is_nothrow_constructible<is_constructible<_Tp>::value, is_reference<_Tp>::value, _Tp>
3146{
3147};
3148
3149#endif // _LIBCPP_HAS_NO_NOEXCEPT
3150
3151
3152#if _LIBCPP_STD_VER > 14
3153template <class _Tp, class ..._Args>
3154inline constexpr bool is_nothrow_constructible_v = is_nothrow_constructible<_Tp, _Args...>::value;
3155#endif
3156
3157// is_nothrow_default_constructible
3158
3159template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_nothrow_default_constructible
3160    : public is_nothrow_constructible<_Tp>
3161    {};
3162
3163#if _LIBCPP_STD_VER > 14
3164template <class _Tp>
3165inline constexpr bool is_nothrow_default_constructible_v = is_nothrow_default_constructible<_Tp>::value;
3166#endif
3167
3168// is_nothrow_copy_constructible
3169
3170template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_nothrow_copy_constructible
3171    : public is_nothrow_constructible<_Tp,
3172                  typename add_lvalue_reference<typename add_const<_Tp>::type>::type> {};
3173
3174#if _LIBCPP_STD_VER > 14
3175template <class _Tp>
3176inline constexpr bool is_nothrow_copy_constructible_v = is_nothrow_copy_constructible<_Tp>::value;
3177#endif
3178
3179// is_nothrow_move_constructible
3180
3181template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_nothrow_move_constructible
3182    : public is_nothrow_constructible<_Tp, typename add_rvalue_reference<_Tp>::type>
3183    {};
3184
3185#if _LIBCPP_STD_VER > 14
3186template <class _Tp>
3187inline constexpr bool is_nothrow_move_constructible_v = is_nothrow_move_constructible<_Tp>::value;
3188#endif
3189
3190// is_nothrow_assignable
3191
3192#if __has_keyword(__is_nothrow_assignable)
3193
3194template <class _Tp, class _Arg>
3195struct _LIBCPP_TEMPLATE_VIS is_nothrow_assignable
3196    : public integral_constant<bool, __is_nothrow_assignable(_Tp, _Arg)> {};
3197
3198#else
3199
3200template <bool, class _Tp, class _Arg> struct __libcpp_is_nothrow_assignable;
3201
3202template <class _Tp, class _Arg>
3203struct __libcpp_is_nothrow_assignable<false, _Tp, _Arg>
3204    : public false_type
3205{
3206};
3207
3208template <class _Tp, class _Arg>
3209struct __libcpp_is_nothrow_assignable<true, _Tp, _Arg>
3210    : public integral_constant<bool, noexcept(declval<_Tp>() = declval<_Arg>()) >
3211{
3212};
3213
3214template <class _Tp, class _Arg>
3215struct _LIBCPP_TEMPLATE_VIS is_nothrow_assignable
3216    : public __libcpp_is_nothrow_assignable<is_assignable<_Tp, _Arg>::value, _Tp, _Arg>
3217{
3218};
3219
3220#endif // _LIBCPP_HAS_NO_NOEXCEPT
3221
3222#if _LIBCPP_STD_VER > 14
3223template <class _Tp, class _Arg>
3224inline constexpr bool is_nothrow_assignable_v = is_nothrow_assignable<_Tp, _Arg>::value;
3225#endif
3226
3227// is_nothrow_copy_assignable
3228
3229template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_nothrow_copy_assignable
3230    : public is_nothrow_assignable<typename add_lvalue_reference<_Tp>::type,
3231                  typename add_lvalue_reference<typename add_const<_Tp>::type>::type> {};
3232
3233#if _LIBCPP_STD_VER > 14
3234template <class _Tp>
3235inline constexpr bool is_nothrow_copy_assignable_v = is_nothrow_copy_assignable<_Tp>::value;
3236#endif
3237
3238// is_nothrow_move_assignable
3239
3240template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_nothrow_move_assignable
3241    : public is_nothrow_assignable<typename add_lvalue_reference<_Tp>::type,
3242                                     typename add_rvalue_reference<_Tp>::type>
3243    {};
3244
3245#if _LIBCPP_STD_VER > 14
3246template <class _Tp>
3247inline constexpr bool is_nothrow_move_assignable_v = is_nothrow_move_assignable<_Tp>::value;
3248#endif
3249
3250// is_nothrow_destructible
3251
3252#if !defined(_LIBCPP_CXX03_LANG)
3253
3254template <bool, class _Tp> struct __libcpp_is_nothrow_destructible;
3255
3256template <class _Tp>
3257struct __libcpp_is_nothrow_destructible<false, _Tp>
3258    : public false_type
3259{
3260};
3261
3262template <class _Tp>
3263struct __libcpp_is_nothrow_destructible<true, _Tp>
3264    : public integral_constant<bool, noexcept(declval<_Tp>().~_Tp()) >
3265{
3266};
3267
3268template <class _Tp>
3269struct _LIBCPP_TEMPLATE_VIS is_nothrow_destructible
3270    : public __libcpp_is_nothrow_destructible<is_destructible<_Tp>::value, _Tp>
3271{
3272};
3273
3274template <class _Tp, size_t _Ns>
3275struct _LIBCPP_TEMPLATE_VIS is_nothrow_destructible<_Tp[_Ns]>
3276    : public is_nothrow_destructible<_Tp>
3277{
3278};
3279
3280template <class _Tp>
3281struct _LIBCPP_TEMPLATE_VIS is_nothrow_destructible<_Tp&>
3282    : public true_type
3283{
3284};
3285
3286template <class _Tp>
3287struct _LIBCPP_TEMPLATE_VIS is_nothrow_destructible<_Tp&&>
3288    : public true_type
3289{
3290};
3291
3292#else
3293
3294template <class _Tp> struct __libcpp_nothrow_destructor
3295    : public integral_constant<bool, is_scalar<_Tp>::value ||
3296                                     is_reference<_Tp>::value> {};
3297
3298template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_nothrow_destructible
3299    : public __libcpp_nothrow_destructor<typename remove_all_extents<_Tp>::type> {};
3300
3301template <class _Tp>
3302struct _LIBCPP_TEMPLATE_VIS is_nothrow_destructible<_Tp[]>
3303    : public false_type {};
3304
3305#endif
3306
3307#if _LIBCPP_STD_VER > 14
3308template <class _Tp>
3309inline constexpr bool is_nothrow_destructible_v = is_nothrow_destructible<_Tp>::value;
3310#endif
3311
3312// is_pod
3313
3314#if __has_feature(is_pod) || defined(_LIBCPP_COMPILER_GCC)
3315
3316template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_pod
3317    : public integral_constant<bool, __is_pod(_Tp)> {};
3318
3319#else
3320
3321template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_pod
3322    : public integral_constant<bool, is_trivially_default_constructible<_Tp>::value   &&
3323                                     is_trivially_copy_constructible<_Tp>::value      &&
3324                                     is_trivially_copy_assignable<_Tp>::value    &&
3325                                     is_trivially_destructible<_Tp>::value> {};
3326
3327#endif
3328
3329#if _LIBCPP_STD_VER > 14
3330template <class _Tp>
3331inline constexpr bool is_pod_v = is_pod<_Tp>::value;
3332#endif
3333
3334// is_literal_type;
3335
3336#if _LIBCPP_STD_VER <= 17 || defined(_LIBCPP_ENABLE_CXX20_REMOVED_TYPE_TRAITS)
3337template <class _Tp> struct _LIBCPP_TEMPLATE_VIS _LIBCPP_DEPRECATED_IN_CXX17 is_literal_type
3338    : public integral_constant<bool, __is_literal_type(_Tp)>
3339    {};
3340
3341#if _LIBCPP_STD_VER > 14
3342template <class _Tp>
3343_LIBCPP_DEPRECATED_IN_CXX17 inline constexpr bool is_literal_type_v = is_literal_type<_Tp>::value;
3344#endif // _LIBCPP_STD_VER > 14
3345#endif // _LIBCPP_STD_VER <= 17 || defined(_LIBCPP_ENABLE_CXX20_REMOVED_TYPE_TRAITS)
3346
3347// is_standard_layout;
3348
3349template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_standard_layout
3350#if __has_feature(is_standard_layout) || defined(_LIBCPP_COMPILER_GCC)
3351    : public integral_constant<bool, __is_standard_layout(_Tp)>
3352#else
3353    : integral_constant<bool, is_scalar<typename remove_all_extents<_Tp>::type>::value>
3354#endif
3355    {};
3356
3357#if _LIBCPP_STD_VER > 14
3358template <class _Tp>
3359inline constexpr bool is_standard_layout_v = is_standard_layout<_Tp>::value;
3360#endif
3361
3362// is_trivially_copyable;
3363
3364template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_trivially_copyable
3365    : public integral_constant<bool, __is_trivially_copyable(_Tp)>
3366    {};
3367
3368#if _LIBCPP_STD_VER > 14
3369template <class _Tp>
3370inline constexpr bool is_trivially_copyable_v = is_trivially_copyable<_Tp>::value;
3371#endif
3372
3373// is_trivial;
3374
3375template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_trivial
3376#if __has_feature(is_trivial) || defined(_LIBCPP_COMPILER_GCC)
3377    : public integral_constant<bool, __is_trivial(_Tp)>
3378#else
3379    : integral_constant<bool, is_trivially_copyable<_Tp>::value &&
3380                                 is_trivially_default_constructible<_Tp>::value>
3381#endif
3382    {};
3383
3384#if _LIBCPP_STD_VER > 14
3385template <class _Tp>
3386inline constexpr bool is_trivial_v = is_trivial<_Tp>::value;
3387#endif
3388
3389template <class _Tp> struct __is_reference_wrapper_impl : public false_type {};
3390template <class _Tp> struct __is_reference_wrapper_impl<reference_wrapper<_Tp> > : public true_type {};
3391template <class _Tp> struct __is_reference_wrapper
3392    : public __is_reference_wrapper_impl<typename remove_cv<_Tp>::type> {};
3393
3394#ifndef _LIBCPP_CXX03_LANG
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_bullet1 = typename enable_if
3401    <
3402        is_member_function_pointer<_DecayFp>::value
3403        && is_base_of<_ClassT, _DecayA0>::value
3404    >::type;
3405
3406template <class _Fp, class _A0,
3407         class _DecayFp = typename decay<_Fp>::type,
3408         class _DecayA0 = typename decay<_A0>::type>
3409using __enable_if_bullet2 = typename enable_if
3410    <
3411        is_member_function_pointer<_DecayFp>::value
3412        && __is_reference_wrapper<_DecayA0>::value
3413    >::type;
3414
3415template <class _Fp, class _A0,
3416         class _DecayFp = typename decay<_Fp>::type,
3417         class _DecayA0 = typename decay<_A0>::type,
3418         class _ClassT = typename __member_pointer_class_type<_DecayFp>::type>
3419using __enable_if_bullet3 = typename enable_if
3420    <
3421        is_member_function_pointer<_DecayFp>::value
3422        && !is_base_of<_ClassT, _DecayA0>::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_bullet4 = typename enable_if
3431    <
3432        is_member_object_pointer<_DecayFp>::value
3433        && is_base_of<_ClassT, _DecayA0>::value
3434    >::type;
3435
3436template <class _Fp, class _A0,
3437         class _DecayFp = typename decay<_Fp>::type,
3438         class _DecayA0 = typename decay<_A0>::type>
3439using __enable_if_bullet5 = typename enable_if
3440    <
3441        is_member_object_pointer<_DecayFp>::value
3442        && __is_reference_wrapper<_DecayA0>::value
3443    >::type;
3444
3445template <class _Fp, class _A0,
3446         class _DecayFp = typename decay<_Fp>::type,
3447         class _DecayA0 = typename decay<_A0>::type,
3448         class _ClassT = typename __member_pointer_class_type<_DecayFp>::type>
3449using __enable_if_bullet6 = typename enable_if
3450    <
3451        is_member_object_pointer<_DecayFp>::value
3452        && !is_base_of<_ClassT, _DecayA0>::value
3453        && !__is_reference_wrapper<_DecayA0>::value
3454    >::type;
3455
3456// __invoke forward declarations
3457
3458// fall back - none of the bullets
3459
3460template <class ..._Args>
3461auto __invoke(__any, _Args&& ...__args) -> __nat;
3462
3463// bullets 1, 2 and 3
3464
3465template <class _Fp, class _A0, class ..._Args,
3466          class = __enable_if_bullet1<_Fp, _A0>>
3467inline _LIBCPP_INLINE_VISIBILITY
3468constexpr auto
3469__invoke(_Fp&& __f, _A0&& __a0, _Args&& ...__args)
3470    noexcept(noexcept((static_cast<_A0&&>(__a0).*__f)(static_cast<_Args&&>(__args)...)))
3471    -> decltype(      (static_cast<_A0&&>(__a0).*__f)(static_cast<_Args&&>(__args)...))
3472    { return          (static_cast<_A0&&>(__a0).*__f)(static_cast<_Args&&>(__args)...); }
3473
3474template <class _Fp, class _A0, class ..._Args,
3475          class = __enable_if_bullet2<_Fp, _A0>>
3476inline _LIBCPP_INLINE_VISIBILITY
3477constexpr auto
3478__invoke(_Fp&& __f, _A0&& __a0, _Args&& ...__args)
3479    noexcept(noexcept((__a0.get().*__f)(static_cast<_Args&&>(__args)...)))
3480    -> decltype(      (__a0.get().*__f)(static_cast<_Args&&>(__args)...))
3481    { return          (__a0.get().*__f)(static_cast<_Args&&>(__args)...); }
3482
3483template <class _Fp, class _A0, class ..._Args,
3484          class = __enable_if_bullet3<_Fp, _A0>>
3485inline _LIBCPP_INLINE_VISIBILITY
3486constexpr auto
3487__invoke(_Fp&& __f, _A0&& __a0, _Args&& ...__args)
3488    noexcept(noexcept(((*static_cast<_A0&&>(__a0)).*__f)(static_cast<_Args&&>(__args)...)))
3489    -> decltype(      ((*static_cast<_A0&&>(__a0)).*__f)(static_cast<_Args&&>(__args)...))
3490    { return          ((*static_cast<_A0&&>(__a0)).*__f)(static_cast<_Args&&>(__args)...); }
3491
3492// bullets 4, 5 and 6
3493
3494template <class _Fp, class _A0,
3495          class = __enable_if_bullet4<_Fp, _A0>>
3496inline _LIBCPP_INLINE_VISIBILITY
3497constexpr auto
3498__invoke(_Fp&& __f, _A0&& __a0)
3499    noexcept(noexcept(static_cast<_A0&&>(__a0).*__f))
3500    -> decltype(      static_cast<_A0&&>(__a0).*__f)
3501    { return          static_cast<_A0&&>(__a0).*__f; }
3502
3503template <class _Fp, class _A0,
3504          class = __enable_if_bullet5<_Fp, _A0>>
3505inline _LIBCPP_INLINE_VISIBILITY
3506constexpr auto
3507__invoke(_Fp&& __f, _A0&& __a0)
3508    noexcept(noexcept(__a0.get().*__f))
3509    -> decltype(      __a0.get().*__f)
3510    { return          __a0.get().*__f; }
3511
3512template <class _Fp, class _A0,
3513          class = __enable_if_bullet6<_Fp, _A0>>
3514inline _LIBCPP_INLINE_VISIBILITY
3515constexpr auto
3516__invoke(_Fp&& __f, _A0&& __a0)
3517    noexcept(noexcept((*static_cast<_A0&&>(__a0)).*__f))
3518    -> decltype(      (*static_cast<_A0&&>(__a0)).*__f)
3519    { return          (*static_cast<_A0&&>(__a0)).*__f; }
3520
3521// bullet 7
3522
3523template <class _Fp, class ..._Args>
3524inline _LIBCPP_INLINE_VISIBILITY
3525constexpr auto
3526__invoke(_Fp&& __f, _Args&& ...__args)
3527    noexcept(noexcept(static_cast<_Fp&&>(__f)(static_cast<_Args&&>(__args)...)))
3528    -> decltype(      static_cast<_Fp&&>(__f)(static_cast<_Args&&>(__args)...))
3529    { return          static_cast<_Fp&&>(__f)(static_cast<_Args&&>(__args)...); }
3530
3531// __invokable
3532template <class _Ret, class _Fp, class ..._Args>
3533struct __invokable_r
3534{
3535  template <class _XFp, class ..._XArgs>
3536  static auto __try_call(int) -> decltype(
3537    _VSTD::__invoke(declval<_XFp>(), declval<_XArgs>()...));
3538  template <class _XFp, class ..._XArgs>
3539  static __nat __try_call(...);
3540
3541  // FIXME: Check that _Ret, _Fp, and _Args... are all complete types, cv void,
3542  // or incomplete array types as required by the standard.
3543  using _Result = decltype(__try_call<_Fp, _Args...>(0));
3544
3545  using type =
3546  typename conditional<
3547      _IsNotSame<_Result, __nat>::value,
3548      typename conditional<
3549          is_void<_Ret>::value,
3550          true_type,
3551          is_convertible<_Result, _Ret>
3552      >::type,
3553      false_type
3554  >::type;
3555  static const bool value = type::value;
3556};
3557template <class _Fp, class ..._Args>
3558using __invokable = __invokable_r<void, _Fp, _Args...>;
3559
3560template <bool _IsInvokable, bool _IsCVVoid, class _Ret, class _Fp, class ..._Args>
3561struct __nothrow_invokable_r_imp {
3562  static const bool value = false;
3563};
3564
3565template <class _Ret, class _Fp, class ..._Args>
3566struct __nothrow_invokable_r_imp<true, false, _Ret, _Fp, _Args...>
3567{
3568    typedef __nothrow_invokable_r_imp _ThisT;
3569
3570    template <class _Tp>
3571    static void __test_noexcept(_Tp) noexcept;
3572
3573    static const bool value = noexcept(_ThisT::__test_noexcept<_Ret>(
3574        _VSTD::__invoke(declval<_Fp>(), declval<_Args>()...)));
3575};
3576
3577template <class _Ret, class _Fp, class ..._Args>
3578struct __nothrow_invokable_r_imp<true, true, _Ret, _Fp, _Args...>
3579{
3580    static const bool value = noexcept(
3581        _VSTD::__invoke(declval<_Fp>(), declval<_Args>()...));
3582};
3583
3584template <class _Ret, class _Fp, class ..._Args>
3585using __nothrow_invokable_r =
3586    __nothrow_invokable_r_imp<
3587            __invokable_r<_Ret, _Fp, _Args...>::value,
3588            is_void<_Ret>::value,
3589            _Ret, _Fp, _Args...
3590    >;
3591
3592template <class _Fp, class ..._Args>
3593using __nothrow_invokable =
3594    __nothrow_invokable_r_imp<
3595            __invokable<_Fp, _Args...>::value,
3596            true, void, _Fp, _Args...
3597    >;
3598
3599template <class _Fp, class ..._Args>
3600struct __invoke_of
3601    : public enable_if<
3602        __invokable<_Fp, _Args...>::value,
3603        typename __invokable_r<void, _Fp, _Args...>::_Result>
3604{
3605};
3606
3607#endif // _LIBCPP_CXX03_LANG
3608
3609// result_of
3610
3611#if _LIBCPP_STD_VER <= 17 || defined(_LIBCPP_ENABLE_CXX20_REMOVED_TYPE_TRAITS)
3612template <class _Callable> class _LIBCPP_DEPRECATED_IN_CXX17 result_of;
3613
3614#ifndef _LIBCPP_CXX03_LANG
3615
3616template <class _Fp, class ..._Args>
3617class _LIBCPP_TEMPLATE_VIS result_of<_Fp(_Args...)>
3618    : public __invoke_of<_Fp, _Args...>
3619{
3620};
3621
3622#else // C++03
3623
3624template <class _Fn, bool, bool>
3625class __result_of
3626{
3627};
3628
3629template <class _Fn, class ..._Args>
3630class __result_of<_Fn(_Args...), true, false>
3631{
3632public:
3633    typedef decltype(declval<_Fn>()(declval<_Args>()...)) type;
3634};
3635
3636template <class _MP, class _Tp, bool _IsMemberFunctionPtr>
3637struct __result_of_mp;
3638
3639// member function pointer
3640
3641template <class _MP, class _Tp>
3642struct __result_of_mp<_MP, _Tp, true>
3643{
3644    using type = typename __member_pointer_traits<_MP>::_ReturnType;
3645};
3646
3647// member data pointer
3648
3649template <class _MP, class _Tp, bool>
3650struct __result_of_mdp;
3651
3652template <class _Rp, class _Class, class _Tp>
3653struct __result_of_mdp<_Rp _Class::*, _Tp, false>
3654{
3655    using type = typename __apply_cv<decltype(*declval<_Tp>()), _Rp>::type&;
3656};
3657
3658template <class _Rp, class _Class, class _Tp>
3659struct __result_of_mdp<_Rp _Class::*, _Tp, true>
3660{
3661    using type = typename __apply_cv<_Tp, _Rp>::type&;
3662};
3663
3664template <class _Rp, class _Class, class _Tp>
3665struct __result_of_mp<_Rp _Class::*, _Tp, false>
3666    : public __result_of_mdp<_Rp _Class::*, _Tp,
3667            is_base_of<_Class, typename remove_reference<_Tp>::type>::value>
3668{
3669};
3670
3671template <class _Fn, class _Tp>
3672class __result_of<_Fn(_Tp), false, true>  // _Fn must be member pointer
3673    : public __result_of_mp<typename remove_reference<_Fn>::type,
3674                            _Tp,
3675                            is_member_function_pointer<typename remove_reference<_Fn>::type>::value>
3676{
3677};
3678
3679template <class _Fn, class _Tp, class ..._Args>
3680class __result_of<_Fn(_Tp, _Args...), false, true>  // _Fn must be member pointer
3681    : public __result_of_mp<typename remove_reference<_Fn>::type,
3682                            _Tp,
3683                            is_member_function_pointer<typename remove_reference<_Fn>::type>::value>
3684{
3685};
3686
3687template <class _Fn, class ..._Args>
3688class _LIBCPP_TEMPLATE_VIS result_of<_Fn(_Args...)>
3689    : public __result_of<_Fn(_Args...),
3690                         is_class<typename remove_reference<_Fn>::type>::value ||
3691                         is_function<typename remove_pointer<typename remove_reference<_Fn>::type>::type>::value,
3692                         is_member_pointer<typename remove_reference<_Fn>::type>::value
3693                        >
3694{
3695};
3696
3697#endif // C++03
3698
3699#if _LIBCPP_STD_VER > 11
3700template <class _Tp> using result_of_t _LIBCPP_DEPRECATED_IN_CXX17 = typename result_of<_Tp>::type;
3701#endif // _LIBCPP_STD_VER > 11
3702#endif // _LIBCPP_STD_VER <= 17 || defined(_LIBCPP_ENABLE_CXX20_REMOVED_TYPE_TRAITS)
3703
3704#if _LIBCPP_STD_VER > 14
3705
3706// invoke_result
3707
3708template <class _Fn, class... _Args>
3709struct _LIBCPP_TEMPLATE_VIS invoke_result
3710    : __invoke_of<_Fn, _Args...>
3711{
3712};
3713
3714template <class _Fn, class... _Args>
3715using invoke_result_t = typename invoke_result<_Fn, _Args...>::type;
3716
3717// is_invocable
3718
3719template <class _Fn, class ..._Args>
3720struct _LIBCPP_TEMPLATE_VIS is_invocable
3721    : integral_constant<bool, __invokable<_Fn, _Args...>::value> {};
3722
3723template <class _Ret, class _Fn, class ..._Args>
3724struct _LIBCPP_TEMPLATE_VIS is_invocable_r
3725    : integral_constant<bool, __invokable_r<_Ret, _Fn, _Args...>::value> {};
3726
3727template <class _Fn, class ..._Args>
3728inline constexpr bool is_invocable_v = is_invocable<_Fn, _Args...>::value;
3729
3730template <class _Ret, class _Fn, class ..._Args>
3731inline constexpr bool is_invocable_r_v = is_invocable_r<_Ret, _Fn, _Args...>::value;
3732
3733// is_nothrow_invocable
3734
3735template <class _Fn, class ..._Args>
3736struct _LIBCPP_TEMPLATE_VIS is_nothrow_invocable
3737    : integral_constant<bool, __nothrow_invokable<_Fn, _Args...>::value> {};
3738
3739template <class _Ret, class _Fn, class ..._Args>
3740struct _LIBCPP_TEMPLATE_VIS is_nothrow_invocable_r
3741    : integral_constant<bool, __nothrow_invokable_r<_Ret, _Fn, _Args...>::value> {};
3742
3743template <class _Fn, class ..._Args>
3744inline constexpr bool is_nothrow_invocable_v = is_nothrow_invocable<_Fn, _Args...>::value;
3745
3746template <class _Ret, class _Fn, class ..._Args>
3747inline constexpr bool is_nothrow_invocable_r_v = is_nothrow_invocable_r<_Ret, _Fn, _Args...>::value;
3748
3749#endif // _LIBCPP_STD_VER > 14
3750
3751// __swappable
3752
3753template <class _Tp> struct __is_swappable;
3754template <class _Tp> struct __is_nothrow_swappable;
3755
3756
3757#ifndef _LIBCPP_CXX03_LANG
3758template <class _Tp>
3759using __swap_result_t = typename enable_if<is_move_constructible<_Tp>::value && is_move_assignable<_Tp>::value>::type;
3760#else
3761template <class>
3762using __swap_result_t = void;
3763#endif
3764
3765template <class _Tp>
3766inline _LIBCPP_INLINE_VISIBILITY
3767_LIBCPP_CONSTEXPR_AFTER_CXX17 __swap_result_t<_Tp>
3768swap(_Tp& __x, _Tp& __y) _NOEXCEPT_(is_nothrow_move_constructible<_Tp>::value &&
3769                                    is_nothrow_move_assignable<_Tp>::value);
3770
3771template<class _Tp, size_t _Np>
3772inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
3773typename enable_if<
3774    __is_swappable<_Tp>::value
3775>::type
3776swap(_Tp (&__a)[_Np], _Tp (&__b)[_Np]) _NOEXCEPT_(__is_nothrow_swappable<_Tp>::value);
3777
3778namespace __detail
3779{
3780// ALL generic swap overloads MUST already have a declaration available at this point.
3781
3782template <class _Tp, class _Up = _Tp,
3783          bool _NotVoid = !is_void<_Tp>::value && !is_void<_Up>::value>
3784struct __swappable_with
3785{
3786    template <class _LHS, class _RHS>
3787    static decltype(swap(declval<_LHS>(), declval<_RHS>()))
3788    __test_swap(int);
3789    template <class, class>
3790    static __nat __test_swap(long);
3791
3792    // Extra parens are needed for the C++03 definition of decltype.
3793    typedef decltype((__test_swap<_Tp, _Up>(0))) __swap1;
3794    typedef decltype((__test_swap<_Up, _Tp>(0))) __swap2;
3795
3796    static const bool value = _IsNotSame<__swap1, __nat>::value
3797                           && _IsNotSame<__swap2, __nat>::value;
3798};
3799
3800template <class _Tp, class _Up>
3801struct __swappable_with<_Tp, _Up,  false> : false_type {};
3802
3803template <class _Tp, class _Up = _Tp, bool _Swappable = __swappable_with<_Tp, _Up>::value>
3804struct __nothrow_swappable_with {
3805  static const bool value =
3806#ifndef _LIBCPP_HAS_NO_NOEXCEPT
3807      noexcept(swap(declval<_Tp>(), declval<_Up>()))
3808  &&  noexcept(swap(declval<_Up>(), declval<_Tp>()));
3809#else
3810      false;
3811#endif
3812};
3813
3814template <class _Tp, class _Up>
3815struct __nothrow_swappable_with<_Tp, _Up, false> : false_type {};
3816
3817} // namespace __detail
3818
3819template <class _Tp>
3820struct __is_swappable
3821    : public integral_constant<bool, __detail::__swappable_with<_Tp&>::value>
3822{
3823};
3824
3825template <class _Tp>
3826struct __is_nothrow_swappable
3827    : public integral_constant<bool, __detail::__nothrow_swappable_with<_Tp&>::value>
3828{
3829};
3830
3831#if _LIBCPP_STD_VER > 14
3832
3833template <class _Tp, class _Up>
3834struct _LIBCPP_TEMPLATE_VIS is_swappable_with
3835    : public integral_constant<bool, __detail::__swappable_with<_Tp, _Up>::value>
3836{
3837};
3838
3839template <class _Tp>
3840struct _LIBCPP_TEMPLATE_VIS is_swappable
3841    : public conditional<
3842        __is_referenceable<_Tp>::value,
3843        is_swappable_with<
3844            typename add_lvalue_reference<_Tp>::type,
3845            typename add_lvalue_reference<_Tp>::type>,
3846        false_type
3847    >::type
3848{
3849};
3850
3851template <class _Tp, class _Up>
3852struct _LIBCPP_TEMPLATE_VIS is_nothrow_swappable_with
3853    : public integral_constant<bool, __detail::__nothrow_swappable_with<_Tp, _Up>::value>
3854{
3855};
3856
3857template <class _Tp>
3858struct _LIBCPP_TEMPLATE_VIS is_nothrow_swappable
3859    : public conditional<
3860        __is_referenceable<_Tp>::value,
3861        is_nothrow_swappable_with<
3862            typename add_lvalue_reference<_Tp>::type,
3863            typename add_lvalue_reference<_Tp>::type>,
3864        false_type
3865    >::type
3866{
3867};
3868
3869template <class _Tp, class _Up>
3870inline constexpr bool is_swappable_with_v = is_swappable_with<_Tp, _Up>::value;
3871
3872template <class _Tp>
3873inline constexpr bool is_swappable_v = is_swappable<_Tp>::value;
3874
3875template <class _Tp, class _Up>
3876inline constexpr bool is_nothrow_swappable_with_v = is_nothrow_swappable_with<_Tp, _Up>::value;
3877
3878template <class _Tp>
3879inline constexpr bool is_nothrow_swappable_v = is_nothrow_swappable<_Tp>::value;
3880
3881#endif // _LIBCPP_STD_VER > 14
3882
3883template <class _Tp, bool = is_enum<_Tp>::value> struct __underlying_type_impl;
3884
3885template <class _Tp>
3886struct __underlying_type_impl<_Tp, false> {};
3887
3888template <class _Tp>
3889struct __underlying_type_impl<_Tp, true>
3890{
3891    typedef __underlying_type(_Tp) type;
3892};
3893
3894template <class _Tp>
3895struct underlying_type : __underlying_type_impl<_Tp, is_enum<_Tp>::value> {};
3896
3897#if _LIBCPP_STD_VER > 11
3898template <class _Tp> using underlying_type_t = typename underlying_type<_Tp>::type;
3899#endif
3900
3901template <class _Tp, bool = is_enum<_Tp>::value>
3902struct __sfinae_underlying_type
3903{
3904    typedef typename underlying_type<_Tp>::type type;
3905    typedef decltype(((type)1) + 0) __promoted_type;
3906};
3907
3908template <class _Tp>
3909struct __sfinae_underlying_type<_Tp, false> {};
3910
3911inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
3912int __convert_to_integral(int __val) { return __val; }
3913
3914inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
3915unsigned __convert_to_integral(unsigned __val) { return __val; }
3916
3917inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
3918long __convert_to_integral(long __val) { return __val; }
3919
3920inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
3921unsigned long __convert_to_integral(unsigned long __val) { return __val; }
3922
3923inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
3924long long __convert_to_integral(long long __val) { return __val; }
3925
3926inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
3927unsigned long long __convert_to_integral(unsigned long long __val) {return __val; }
3928
3929template<typename _Fp>
3930inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
3931typename enable_if<is_floating_point<_Fp>::value, long long>::type
3932 __convert_to_integral(_Fp __val) { return __val; }
3933
3934#ifndef _LIBCPP_HAS_NO_INT128
3935inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
3936__int128_t __convert_to_integral(__int128_t __val) { return __val; }
3937
3938inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
3939__uint128_t __convert_to_integral(__uint128_t __val) { return __val; }
3940#endif
3941
3942template <class _Tp>
3943inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
3944typename __sfinae_underlying_type<_Tp>::__promoted_type
3945__convert_to_integral(_Tp __val) { return __val; }
3946
3947// is_scoped_enum [meta.unary.prop]
3948
3949#if _LIBCPP_STD_VER > 20
3950template <class _Tp, bool = is_enum_v<_Tp> >
3951struct __is_scoped_enum_helper : false_type {};
3952
3953template <class _Tp>
3954struct __is_scoped_enum_helper<_Tp, true>
3955    : public bool_constant<!is_convertible_v<_Tp, underlying_type_t<_Tp> > > {};
3956
3957template <class _Tp>
3958struct _LIBCPP_TEMPLATE_VIS is_scoped_enum
3959    : public __is_scoped_enum_helper<_Tp> {};
3960
3961template <class _Tp>
3962inline constexpr bool is_scoped_enum_v = is_scoped_enum<_Tp>::value;
3963#endif
3964
3965#if _LIBCPP_STD_VER > 14
3966
3967template <class... _Args>
3968struct conjunction : _And<_Args...> {};
3969template<class... _Args>
3970inline constexpr bool conjunction_v = conjunction<_Args...>::value;
3971
3972template <class... _Args>
3973struct disjunction : _Or<_Args...> {};
3974template<class... _Args>
3975inline constexpr bool disjunction_v = disjunction<_Args...>::value;
3976
3977template <class _Tp>
3978struct negation : _Not<_Tp> {};
3979template<class _Tp>
3980inline constexpr bool negation_v = negation<_Tp>::value;
3981#endif // _LIBCPP_STD_VER > 14
3982
3983// These traits are used in __tree and __hash_table
3984struct __extract_key_fail_tag {};
3985struct __extract_key_self_tag {};
3986struct __extract_key_first_tag {};
3987
3988template <class _ValTy, class _Key,
3989          class _RawValTy = typename __unconstref<_ValTy>::type>
3990struct __can_extract_key
3991    : conditional<_IsSame<_RawValTy, _Key>::value, __extract_key_self_tag,
3992                  __extract_key_fail_tag>::type {};
3993
3994template <class _Pair, class _Key, class _First, class _Second>
3995struct __can_extract_key<_Pair, _Key, pair<_First, _Second> >
3996    : conditional<_IsSame<typename remove_const<_First>::type, _Key>::value,
3997                  __extract_key_first_tag, __extract_key_fail_tag>::type {};
3998
3999// __can_extract_map_key uses true_type/false_type instead of the tags.
4000// It returns true if _Key != _ContainerValueTy (the container is a map not a set)
4001// and _ValTy == _Key.
4002template <class _ValTy, class _Key, class _ContainerValueTy,
4003          class _RawValTy = typename __unconstref<_ValTy>::type>
4004struct __can_extract_map_key
4005    : integral_constant<bool, _IsSame<_RawValTy, _Key>::value> {};
4006
4007// This specialization returns __extract_key_fail_tag for non-map containers
4008// because _Key == _ContainerValueTy
4009template <class _ValTy, class _Key, class _RawValTy>
4010struct __can_extract_map_key<_ValTy, _Key, _Key, _RawValTy>
4011    : false_type {};
4012
4013#if _LIBCPP_STD_VER > 17
4014_LIBCPP_INLINE_VISIBILITY
4015inline constexpr bool is_constant_evaluated() noexcept {
4016  return __builtin_is_constant_evaluated();
4017}
4018#endif
4019
4020inline _LIBCPP_CONSTEXPR
4021bool __libcpp_is_constant_evaluated() _NOEXCEPT { return __builtin_is_constant_evaluated(); }
4022
4023template <class _CharT>
4024using _IsCharLikeType = _And<is_standard_layout<_CharT>, is_trivial<_CharT> >;
4025
4026template<class _Tp>
4027using __make_const_lvalue_ref = const typename remove_reference<_Tp>::type&;
4028
4029#if _LIBCPP_STD_VER > 17
4030template<bool _Const, class _Tp>
4031using __maybe_const = conditional_t<_Const, const _Tp, _Tp>;
4032#endif // _LIBCPP_STD_VER > 17
4033
4034_LIBCPP_END_NAMESPACE_STD
4035
4036#endif // _LIBCPP_TYPE_TRAITS
4037