xref: /freebsd/contrib/llvm-project/libcxx/include/tuple (revision 88b8b7f0c4e9948667a2279e78e975a784049cba)
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_TUPLE
11#define _LIBCPP_TUPLE
12
13// clang-format off
14
15/*
16    tuple synopsis
17
18namespace std
19{
20
21template <class... T>
22class tuple {
23public:
24    explicit(see-below) constexpr tuple();
25    explicit(see-below) tuple(const T&...);  // constexpr in C++14
26    template <class... U>
27        explicit(see-below) tuple(U&&...);  // constexpr in C++14
28    tuple(const tuple&) = default;
29    tuple(tuple&&) = default;
30
31    template<class... UTypes>
32        constexpr explicit(see-below) tuple(tuple<UTypes...>&);  // C++23
33    template <class... U>
34        explicit(see-below) tuple(const tuple<U...>&);  // constexpr in C++14
35    template <class... U>
36        explicit(see-below) tuple(tuple<U...>&&);  // constexpr in C++14
37    template<class... UTypes>
38        constexpr explicit(see-below) tuple(const tuple<UTypes...>&&); // C++23
39
40    template<class U1, class U2>
41        constexpr explicit(see-below) tuple(pair<U1, U2>&);  // iff sizeof...(Types) == 2 // C++23
42    template <class U1, class U2>
43        explicit(see-below) tuple(const pair<U1, U2>&); // iff sizeof...(T) == 2 // constexpr in C++14
44    template <class U1, class U2>
45        explicit(see-below) tuple(pair<U1, U2>&&); // iff sizeof...(T) == 2  // constexpr in C++14
46    template<class U1, class U2>
47        constexpr explicit(see-below) tuple(const pair<U1, U2>&&);  // iff sizeof...(Types) == 2 // C++23
48
49    // allocator-extended constructors
50    template <class Alloc>
51        tuple(allocator_arg_t, const Alloc& a);
52    template <class Alloc>
53        explicit(see-below) tuple(allocator_arg_t, const Alloc& a, const T&...);          // constexpr in C++20
54    template <class Alloc, class... U>
55        explicit(see-below) tuple(allocator_arg_t, const Alloc& a, U&&...);               // constexpr in C++20
56    template <class Alloc>
57        tuple(allocator_arg_t, const Alloc& a, const tuple&);                             // constexpr in C++20
58    template <class Alloc>
59        tuple(allocator_arg_t, const Alloc& a, tuple&&);                                  // constexpr in C++20
60    template<class Alloc, class... UTypes>
61        constexpr explicit(see-below)
62          tuple(allocator_arg_t, const Alloc& a, tuple<UTypes...>&);                      // C++23
63    template <class Alloc, class... U>
64        explicit(see-below) tuple(allocator_arg_t, const Alloc& a, const tuple<U...>&);   // constexpr in C++20
65    template <class Alloc, class... U>
66        explicit(see-below) tuple(allocator_arg_t, const Alloc& a, tuple<U...>&&);        // constexpr in C++20
67    template<class Alloc, class... UTypes>
68        constexpr explicit(see-below)
69          tuple(allocator_arg_t, const Alloc& a, const tuple<UTypes...>&&);               // C++23
70    template<class Alloc, class U1, class U2>
71        constexpr explicit(see-below)
72          tuple(allocator_arg_t, const Alloc& a, pair<U1, U2>&);                          // C++23
73    template <class Alloc, class U1, class U2>
74        explicit(see-below) tuple(allocator_arg_t, const Alloc& a, const pair<U1, U2>&);  // constexpr in C++20
75    template <class Alloc, class U1, class U2>
76        explicit(see-below) tuple(allocator_arg_t, const Alloc& a, pair<U1, U2>&&);       // constexpr in C++20
77    template<class Alloc, class U1, class U2>
78        constexpr explicit(see-below)
79          tuple(allocator_arg_t, const Alloc& a, const pair<U1, U2>&&);                   // C++23
80
81    tuple& operator=(const tuple&);                                                       // constexpr in C++20
82    constexpr const tuple& operator=(const tuple&) const;                                 // C++23
83    tuple& operator=(tuple&&) noexcept(is_nothrow_move_assignable_v<T> && ...);           // constexpr in C++20
84    constexpr const tuple& operator=(tuple&&) const;                                      // C++23
85    template <class... U>
86        tuple& operator=(const tuple<U...>&);                                             // constexpr in C++20
87    template<class... UTypes>
88        constexpr const tuple& operator=(const tuple<UTypes...>&) const;                  // C++23
89    template <class... U>
90        tuple& operator=(tuple<U...>&&);                                                  // constexpr in C++20
91    template<class... UTypes>
92        constexpr const tuple& operator=(tuple<UTypes...>&&) const;                       // C++23
93    template <class U1, class U2>
94        tuple& operator=(const pair<U1, U2>&); // iff sizeof...(T) == 2                   // constexpr in C++20
95    template<class U1, class U2>
96        constexpr const tuple& operator=(const pair<U1, U2>&) const;   // iff sizeof...(Types) == 2 // C++23
97    template <class U1, class U2>
98        tuple& operator=(pair<U1, U2>&&); // iff sizeof...(T) == 2                        // constexpr in C++20
99    template<class U1, class U2>
100        constexpr const tuple& operator=(pair<U1, U2>&&) const;  // iff sizeof...(Types) == 2 // C++23
101
102    template<class U, size_t N>
103        tuple& operator=(array<U, N> const&) // iff sizeof...(T) == N, EXTENSION
104    template<class U, size_t N>
105        tuple& operator=(array<U, N>&&) // iff sizeof...(T) == N, EXTENSION
106
107    void swap(tuple&) noexcept(AND(swap(declval<T&>(), declval<T&>())...));               // constexpr in C++20
108    constexpr void swap(const tuple&) const noexcept(see-below);                          // C++23
109};
110
111
112template<class... TTypes, class... UTypes, template<class> class TQual, template<class> class UQual> // since C++23
113  requires requires { typename tuple<common_reference_t<TQual<TTypes>, UQual<UTypes>>...>; }
114struct basic_common_reference<tuple<TTypes...>, tuple<UTypes...>, TQual, UQual> {
115  using type = tuple<common_reference_t<TQual<TTypes>, UQual<UTypes>>...>;
116};
117
118template<class... TTypes, class... UTypes>                                // since C++23
119  requires requires { typename tuple<common_type_t<TTypes, UTypes>...>; }
120struct common_type<tuple<TTypes...>, tuple<UTypes...>> {
121  using type = tuple<common_type_t<TTypes, UTypes>...>;
122};
123
124template <class ...T>
125tuple(T...) -> tuple<T...>;                                         // since C++17
126template <class T1, class T2>
127tuple(pair<T1, T2>) -> tuple<T1, T2>;                               // since C++17
128template <class Alloc, class ...T>
129tuple(allocator_arg_t, Alloc, T...) -> tuple<T...>;                 // since C++17
130template <class Alloc, class T1, class T2>
131tuple(allocator_arg_t, Alloc, pair<T1, T2>) -> tuple<T1, T2>;       // since C++17
132template <class Alloc, class ...T>
133tuple(allocator_arg_t, Alloc, tuple<T...>) -> tuple<T...>;          // since C++17
134
135struct ignore-type { // exposition only                             // Since C++26
136  constexpr const ignore-type&
137    operator=(const auto &) const noexcept
138      { return *this; }
139};
140inline constexpr ignore-type ignore;
141
142template <class... T> tuple<V...>  make_tuple(T&&...); // constexpr in C++14
143template <class... T> tuple<ATypes...> forward_as_tuple(T&&...) noexcept; // constexpr in C++14
144template <class... T> tuple<T&...> tie(T&...) noexcept; // constexpr in C++14
145template <class... Tuples> tuple<CTypes...> tuple_cat(Tuples&&... tpls); // constexpr in C++14
146
147// [tuple.apply], calling a function with a tuple of arguments:
148template <class F, class Tuple>
149  constexpr decltype(auto) apply(F&& f, Tuple&& t) noexcept(see below);  // C++17 noexcept since C++23
150template <class T, class Tuple>
151  constexpr T make_from_tuple(Tuple&& t); // C++17
152
153// 20.4.1.4, tuple helper classes:
154template <class T> struct tuple_size; // undefined
155template <class... T> struct tuple_size<tuple<T...>>;
156template <class T>
157 inline constexpr size_t tuple_size_v = tuple_size<T>::value; // C++17
158template <size_t I, class T> struct tuple_element; // undefined
159template <size_t I, class... T> struct tuple_element<I, tuple<T...>>;
160template <size_t I, class T>
161  using tuple_element_t = typename tuple_element <I, T>::type; // C++14
162
163// 20.4.1.5, element access:
164template <size_t I, class... T>
165    typename tuple_element<I, tuple<T...>>::type&
166    get(tuple<T...>&) noexcept; // constexpr in C++14
167template <size_t I, class... T>
168    const typename tuple_element<I, tuple<T...>>::type&
169    get(const tuple<T...>&) noexcept; // constexpr in C++14
170template <size_t I, class... T>
171    typename tuple_element<I, tuple<T...>>::type&&
172    get(tuple<T...>&&) noexcept; // constexpr in C++14
173template <size_t I, class... T>
174    const typename tuple_element<I, tuple<T...>>::type&&
175    get(const tuple<T...>&&) noexcept; // constexpr in C++14
176
177template <class T1, class... T>
178    constexpr T1& get(tuple<T...>&) noexcept;  // C++14
179template <class T1, class... T>
180    constexpr const T1& get(const tuple<T...>&) noexcept;   // C++14
181template <class T1, class... T>
182    constexpr T1&& get(tuple<T...>&&) noexcept;   // C++14
183template <class T1, class... T>
184    constexpr const T1&& get(const tuple<T...>&&) noexcept;   // C++14
185
186// 20.4.1.6, relational operators:
187template<class... T, class... U> bool operator==(const tuple<T...>&, const tuple<U...>&); // constexpr in C++14
188template<class... T, class... U> bool operator<(const tuple<T...>&, const tuple<U...>&);  // constexpr in C++14, removed in C++20
189template<class... T, class... U> bool operator!=(const tuple<T...>&, const tuple<U...>&); // constexpr in C++14, removed in C++20
190template<class... T, class... U> bool operator>(const tuple<T...>&, const tuple<U...>&);  // constexpr in C++14, removed in C++20
191template<class... T, class... U> bool operator<=(const tuple<T...>&, const tuple<U...>&); // constexpr in C++14, removed in C++20
192template<class... T, class... U> bool operator>=(const tuple<T...>&, const tuple<U...>&); // constexpr in C++14, removed in C++20
193template<class... T, class... U>
194  constexpr common_comparison_category_t<synth-three-way-result<T, U>...>
195    operator<=>(const tuple<T...>&, const tuple<U...>&);                                  // since C++20
196
197template <class... Types, class Alloc>
198  struct uses_allocator<tuple<Types...>, Alloc>;
199
200template <class... Types>
201  void
202  swap(tuple<Types...>& x, tuple<Types...>& y) noexcept(noexcept(x.swap(y)));
203
204template <class... Types>
205  constexpr void swap(const tuple<Types...>& x, const tuple<Types...>& y) noexcept(see-below);   // C++23
206
207}  // std
208
209*/
210
211// clang-format on
212
213#include <__compare/common_comparison_category.h>
214#include <__compare/synth_three_way.h>
215#include <__config>
216#include <__functional/invoke.h>
217#include <__fwd/array.h>
218#include <__fwd/pair.h>
219#include <__fwd/tuple.h>
220#include <__memory/allocator_arg_t.h>
221#include <__memory/uses_allocator.h>
222#include <__tuple/find_index.h>
223#include <__tuple/ignore.h>
224#include <__tuple/make_tuple_types.h>
225#include <__tuple/sfinae_helpers.h>
226#include <__tuple/tuple_element.h>
227#include <__tuple/tuple_indices.h>
228#include <__tuple/tuple_like_ext.h>
229#include <__tuple/tuple_size.h>
230#include <__tuple/tuple_types.h>
231#include <__type_traits/common_reference.h>
232#include <__type_traits/common_type.h>
233#include <__type_traits/conditional.h>
234#include <__type_traits/conjunction.h>
235#include <__type_traits/copy_cvref.h>
236#include <__type_traits/disjunction.h>
237#include <__type_traits/is_arithmetic.h>
238#include <__type_traits/is_assignable.h>
239#include <__type_traits/is_constructible.h>
240#include <__type_traits/is_convertible.h>
241#include <__type_traits/is_empty.h>
242#include <__type_traits/is_final.h>
243#include <__type_traits/is_implicitly_default_constructible.h>
244#include <__type_traits/is_nothrow_assignable.h>
245#include <__type_traits/is_nothrow_constructible.h>
246#include <__type_traits/is_reference.h>
247#include <__type_traits/is_same.h>
248#include <__type_traits/is_swappable.h>
249#include <__type_traits/is_trivially_relocatable.h>
250#include <__type_traits/lazy.h>
251#include <__type_traits/maybe_const.h>
252#include <__type_traits/nat.h>
253#include <__type_traits/negation.h>
254#include <__type_traits/remove_cvref.h>
255#include <__type_traits/remove_reference.h>
256#include <__type_traits/unwrap_ref.h>
257#include <__utility/forward.h>
258#include <__utility/integer_sequence.h>
259#include <__utility/move.h>
260#include <__utility/piecewise_construct.h>
261#include <__utility/swap.h>
262#include <cstddef>
263#include <version>
264
265// standard-mandated includes
266
267// [tuple.syn]
268#include <compare>
269
270#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
271#  pragma GCC system_header
272#endif
273
274_LIBCPP_PUSH_MACROS
275#include <__undef_macros>
276
277_LIBCPP_BEGIN_NAMESPACE_STD
278
279#ifndef _LIBCPP_CXX03_LANG
280
281// __tuple_leaf
282
283template <size_t _Ip, class _Hp, bool = is_empty<_Hp>::value && !__libcpp_is_final<_Hp>::value >
284class __tuple_leaf;
285
286template <size_t _Ip, class _Hp, bool _Ep>
287inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 void
288swap(__tuple_leaf<_Ip, _Hp, _Ep>& __x, __tuple_leaf<_Ip, _Hp, _Ep>& __y) noexcept(__is_nothrow_swappable_v<_Hp>) {
289  swap(__x.get(), __y.get());
290}
291
292template <size_t _Ip, class _Hp, bool _Ep>
293_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 void
294swap(const __tuple_leaf<_Ip, _Hp, _Ep>& __x,
295     const __tuple_leaf<_Ip, _Hp, _Ep>& __y) noexcept(__is_nothrow_swappable_v<const _Hp>) {
296  swap(__x.get(), __y.get());
297}
298
299template <size_t _Ip, class _Hp, bool>
300class __tuple_leaf {
301  _Hp __value_;
302
303  template <class _Tp>
304  static _LIBCPP_HIDE_FROM_ABI constexpr bool __can_bind_reference() {
305#  if __has_keyword(__reference_constructs_from_temporary)
306    return !__reference_constructs_from_temporary(_Hp, _Tp);
307#  elif __has_keyword(__reference_binds_to_temporary)
308    return !__reference_binds_to_temporary(_Hp, _Tp);
309#  else
310    return true;
311#  endif
312  }
313
314public:
315  _LIBCPP_CONSTEXPR_SINCE_CXX14 __tuple_leaf& operator=(const __tuple_leaf&) = delete;
316
317  _LIBCPP_HIDE_FROM_ABI constexpr __tuple_leaf() noexcept(is_nothrow_default_constructible<_Hp>::value) : __value_() {
318    static_assert(!is_reference<_Hp>::value, "Attempted to default construct a reference element in a tuple");
319  }
320
321  template <class _Alloc>
322  _LIBCPP_HIDE_FROM_ABI constexpr __tuple_leaf(integral_constant<int, 0>, const _Alloc&) : __value_() {
323    static_assert(!is_reference<_Hp>::value, "Attempted to default construct a reference element in a tuple");
324  }
325
326  template <class _Alloc>
327  _LIBCPP_HIDE_FROM_ABI constexpr __tuple_leaf(integral_constant<int, 1>, const _Alloc& __a)
328      : __value_(allocator_arg_t(), __a) {
329    static_assert(!is_reference<_Hp>::value, "Attempted to default construct a reference element in a tuple");
330  }
331
332  template <class _Alloc>
333  _LIBCPP_HIDE_FROM_ABI constexpr __tuple_leaf(integral_constant<int, 2>, const _Alloc& __a) : __value_(__a) {
334    static_assert(!is_reference<_Hp>::value, "Attempted to default construct a reference element in a tuple");
335  }
336
337  template <
338      class _Tp,
339      __enable_if_t<_And<_IsNotSame<__remove_cvref_t<_Tp>, __tuple_leaf>, is_constructible<_Hp, _Tp> >::value, int> = 0>
340  _LIBCPP_HIDE_FROM_ABI
341  _LIBCPP_CONSTEXPR_SINCE_CXX14 explicit __tuple_leaf(_Tp&& __t) noexcept(is_nothrow_constructible<_Hp, _Tp>::value)
342      : __value_(std::forward<_Tp>(__t)) {
343    static_assert(__can_bind_reference<_Tp&&>(),
344                  "Attempted construction of reference element binds to a temporary whose lifetime has ended");
345  }
346
347  template <class _Tp, class _Alloc>
348  _LIBCPP_HIDE_FROM_ABI
349  _LIBCPP_CONSTEXPR_SINCE_CXX14 explicit __tuple_leaf(integral_constant<int, 0>, const _Alloc&, _Tp&& __t)
350      : __value_(std::forward<_Tp>(__t)) {
351    static_assert(__can_bind_reference<_Tp&&>(),
352                  "Attempted construction of reference element binds to a temporary whose lifetime has ended");
353  }
354
355  template <class _Tp, class _Alloc>
356  _LIBCPP_HIDE_FROM_ABI
357  _LIBCPP_CONSTEXPR_SINCE_CXX14 explicit __tuple_leaf(integral_constant<int, 1>, const _Alloc& __a, _Tp&& __t)
358      : __value_(allocator_arg_t(), __a, std::forward<_Tp>(__t)) {
359    static_assert(!is_reference<_Hp>::value, "Attempted to uses-allocator construct a reference element in a tuple");
360  }
361
362  template <class _Tp, class _Alloc>
363  _LIBCPP_HIDE_FROM_ABI
364  _LIBCPP_CONSTEXPR_SINCE_CXX14 explicit __tuple_leaf(integral_constant<int, 2>, const _Alloc& __a, _Tp&& __t)
365      : __value_(std::forward<_Tp>(__t), __a) {
366    static_assert(!is_reference<_Hp>::value, "Attempted to uses-allocator construct a reference element in a tuple");
367  }
368
369  _LIBCPP_HIDE_FROM_ABI __tuple_leaf(const __tuple_leaf& __t) = default;
370  _LIBCPP_HIDE_FROM_ABI __tuple_leaf(__tuple_leaf&& __t)      = default;
371
372  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 int
373  swap(__tuple_leaf& __t) noexcept(__is_nothrow_swappable_v<__tuple_leaf>) {
374    std::swap(*this, __t);
375    return 0;
376  }
377
378  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 int swap(const __tuple_leaf& __t) const
379      noexcept(__is_nothrow_swappable_v<const __tuple_leaf>) {
380    std::swap(*this, __t);
381    return 0;
382  }
383
384  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 _Hp& get() _NOEXCEPT { return __value_; }
385  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 const _Hp& get() const _NOEXCEPT { return __value_; }
386};
387
388template <size_t _Ip, class _Hp>
389class __tuple_leaf<_Ip, _Hp, true> : private _Hp {
390public:
391  _LIBCPP_CONSTEXPR_SINCE_CXX14 __tuple_leaf& operator=(const __tuple_leaf&) = delete;
392
393  _LIBCPP_HIDE_FROM_ABI constexpr __tuple_leaf() noexcept(is_nothrow_default_constructible<_Hp>::value) {}
394
395  template <class _Alloc>
396  _LIBCPP_HIDE_FROM_ABI constexpr __tuple_leaf(integral_constant<int, 0>, const _Alloc&) {}
397
398  template <class _Alloc>
399  _LIBCPP_HIDE_FROM_ABI constexpr __tuple_leaf(integral_constant<int, 1>, const _Alloc& __a)
400      : _Hp(allocator_arg_t(), __a) {}
401
402  template <class _Alloc>
403  _LIBCPP_HIDE_FROM_ABI constexpr __tuple_leaf(integral_constant<int, 2>, const _Alloc& __a) : _Hp(__a) {}
404
405  template <class _Tp,
406            __enable_if_t< _And< _IsNotSame<__remove_cvref_t<_Tp>, __tuple_leaf>, is_constructible<_Hp, _Tp> >::value,
407                           int> = 0>
408  _LIBCPP_HIDE_FROM_ABI
409  _LIBCPP_CONSTEXPR_SINCE_CXX14 explicit __tuple_leaf(_Tp&& __t) noexcept(is_nothrow_constructible<_Hp, _Tp>::value)
410      : _Hp(std::forward<_Tp>(__t)) {}
411
412  template <class _Tp, class _Alloc>
413  _LIBCPP_HIDE_FROM_ABI constexpr explicit __tuple_leaf(integral_constant<int, 0>, const _Alloc&, _Tp&& __t)
414      : _Hp(std::forward<_Tp>(__t)) {}
415
416  template <class _Tp, class _Alloc>
417  _LIBCPP_HIDE_FROM_ABI constexpr explicit __tuple_leaf(integral_constant<int, 1>, const _Alloc& __a, _Tp&& __t)
418      : _Hp(allocator_arg_t(), __a, std::forward<_Tp>(__t)) {}
419
420  template <class _Tp, class _Alloc>
421  _LIBCPP_HIDE_FROM_ABI constexpr explicit __tuple_leaf(integral_constant<int, 2>, const _Alloc& __a, _Tp&& __t)
422      : _Hp(std::forward<_Tp>(__t), __a) {}
423
424  __tuple_leaf(__tuple_leaf const&) = default;
425  __tuple_leaf(__tuple_leaf&&)      = default;
426
427  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 int
428  swap(__tuple_leaf& __t) noexcept(__is_nothrow_swappable_v<__tuple_leaf>) {
429    std::swap(*this, __t);
430    return 0;
431  }
432
433  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 int swap(const __tuple_leaf& __rhs) const
434      noexcept(__is_nothrow_swappable_v<const __tuple_leaf>) {
435    std::swap(*this, __rhs);
436    return 0;
437  }
438
439  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 _Hp& get() _NOEXCEPT { return static_cast<_Hp&>(*this); }
440  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 const _Hp& get() const _NOEXCEPT {
441    return static_cast<const _Hp&>(*this);
442  }
443};
444
445template <class... _Tp>
446_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 void __swallow(_Tp&&...) _NOEXCEPT {}
447
448template <class _Tp>
449struct __all_default_constructible;
450
451template <class... _Tp>
452struct __all_default_constructible<__tuple_types<_Tp...>> : __all<is_default_constructible<_Tp>::value...> {};
453
454// __tuple_impl
455
456template <class _Indx, class... _Tp>
457struct __tuple_impl;
458
459template <size_t... _Indx, class... _Tp>
460struct _LIBCPP_DECLSPEC_EMPTY_BASES __tuple_impl<__tuple_indices<_Indx...>, _Tp...>
461    : public __tuple_leaf<_Indx, _Tp>... {
462  _LIBCPP_HIDE_FROM_ABI constexpr __tuple_impl() noexcept(
463      __all<is_nothrow_default_constructible<_Tp>::value...>::value) {}
464
465  template <size_t... _Uf, class... _Tf, size_t... _Ul, class... _Tl, class... _Up>
466  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 explicit __tuple_impl(
467      __tuple_indices<_Uf...>,
468      __tuple_types<_Tf...>,
469      __tuple_indices<_Ul...>,
470      __tuple_types<_Tl...>,
471      _Up&&... __u) noexcept(__all<is_nothrow_constructible<_Tf, _Up>::value...>::value &&
472                             __all<is_nothrow_default_constructible<_Tl>::value...>::value)
473      : __tuple_leaf<_Uf, _Tf>(std::forward<_Up>(__u))..., __tuple_leaf<_Ul, _Tl>()... {}
474
475  template <class _Alloc, size_t... _Uf, class... _Tf, size_t... _Ul, class... _Tl, class... _Up>
476  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 explicit __tuple_impl(
477      allocator_arg_t,
478      const _Alloc& __a,
479      __tuple_indices<_Uf...>,
480      __tuple_types<_Tf...>,
481      __tuple_indices<_Ul...>,
482      __tuple_types<_Tl...>,
483      _Up&&... __u)
484      : __tuple_leaf<_Uf, _Tf>(__uses_alloc_ctor<_Tf, _Alloc, _Up>(), __a, std::forward<_Up>(__u))...,
485        __tuple_leaf<_Ul, _Tl>(__uses_alloc_ctor<_Tl, _Alloc>(), __a)... {}
486
487  template <class _Tuple, __enable_if_t<__tuple_constructible<_Tuple, tuple<_Tp...> >::value, int> = 0>
488  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 __tuple_impl(_Tuple&& __t) noexcept(
489      (__all<is_nothrow_constructible<
490           _Tp,
491           typename tuple_element<_Indx, typename __make_tuple_types<_Tuple>::type>::type>::value...>::value))
492      : __tuple_leaf<_Indx, _Tp>(
493            std::forward<typename tuple_element<_Indx, typename __make_tuple_types<_Tuple>::type>::type>(
494                std::get<_Indx>(__t)))... {}
495
496  template <class _Alloc, class _Tuple, __enable_if_t<__tuple_constructible<_Tuple, tuple<_Tp...> >::value, int> = 0>
497  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 __tuple_impl(allocator_arg_t, const _Alloc& __a, _Tuple&& __t)
498      : __tuple_leaf<_Indx, _Tp>(
499            __uses_alloc_ctor<_Tp,
500                              _Alloc,
501                              typename tuple_element<_Indx, typename __make_tuple_types<_Tuple>::type>::type>(),
502            __a,
503            std::forward<typename tuple_element<_Indx, typename __make_tuple_types<_Tuple>::type>::type>(
504                std::get<_Indx>(__t)))... {}
505
506  __tuple_impl(const __tuple_impl&) = default;
507  __tuple_impl(__tuple_impl&&)      = default;
508
509  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 void
510  swap(__tuple_impl& __t) noexcept(__all<__is_nothrow_swappable_v<_Tp>...>::value) {
511    std::__swallow(__tuple_leaf<_Indx, _Tp>::swap(static_cast<__tuple_leaf<_Indx, _Tp>&>(__t))...);
512  }
513
514  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 void swap(const __tuple_impl& __t) const
515      noexcept(__all<__is_nothrow_swappable_v<const _Tp>...>::value) {
516    std::__swallow(__tuple_leaf<_Indx, _Tp>::swap(static_cast<const __tuple_leaf<_Indx, _Tp>&>(__t))...);
517  }
518};
519
520template <class _Dest, class _Source, size_t... _Np>
521_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 void
522__memberwise_copy_assign(_Dest& __dest, _Source const& __source, __tuple_indices<_Np...>) {
523  std::__swallow(((std::get<_Np>(__dest) = std::get<_Np>(__source)), void(), 0)...);
524}
525
526template <class _Dest, class _Source, class... _Up, size_t... _Np>
527_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 void
528__memberwise_forward_assign(_Dest& __dest, _Source&& __source, __tuple_types<_Up...>, __tuple_indices<_Np...>) {
529  std::__swallow(((std::get<_Np>(__dest) = std::forward<_Up>(std::get<_Np>(__source))), void(), 0)...);
530}
531
532template <class... _Tp>
533class _LIBCPP_TEMPLATE_VIS tuple {
534  typedef __tuple_impl<typename __make_tuple_indices<sizeof...(_Tp)>::type, _Tp...> _BaseT;
535
536  _BaseT __base_;
537
538  template <size_t _Jp, class... _Up>
539  friend _LIBCPP_CONSTEXPR_SINCE_CXX14 typename tuple_element<_Jp, tuple<_Up...> >::type& get(tuple<_Up...>&) _NOEXCEPT;
540  template <size_t _Jp, class... _Up>
541  friend _LIBCPP_CONSTEXPR_SINCE_CXX14 const typename tuple_element<_Jp, tuple<_Up...> >::type&
542  get(const tuple<_Up...>&) _NOEXCEPT;
543  template <size_t _Jp, class... _Up>
544  friend _LIBCPP_CONSTEXPR_SINCE_CXX14 typename tuple_element<_Jp, tuple<_Up...> >::type&&
545  get(tuple<_Up...>&&) _NOEXCEPT;
546  template <size_t _Jp, class... _Up>
547  friend _LIBCPP_CONSTEXPR_SINCE_CXX14 const typename tuple_element<_Jp, tuple<_Up...> >::type&&
548  get(const tuple<_Up...>&&) _NOEXCEPT;
549
550public:
551  using __trivially_relocatable = __conditional_t<_And<__libcpp_is_trivially_relocatable<_Tp>...>::value, tuple, void>;
552
553  // [tuple.cnstr]
554
555  // tuple() constructors (including allocator_arg_t variants)
556  template <template <class...> class _IsImpDefault                = __is_implicitly_default_constructible,
557            template <class...> class _IsDefault                   = is_default_constructible,
558            __enable_if_t< _And< _IsDefault<_Tp>... >::value, int> = 0>
559  _LIBCPP_HIDE_FROM_ABI constexpr explicit(_Not<_Lazy<_And, _IsImpDefault<_Tp>...> >::value)
560      tuple() noexcept(_And<is_nothrow_default_constructible<_Tp>...>::value) {}
561
562  template <class _Alloc,
563            template <class...> class _IsImpDefault                = __is_implicitly_default_constructible,
564            template <class...> class _IsDefault                   = is_default_constructible,
565            __enable_if_t< _And< _IsDefault<_Tp>... >::value, int> = 0>
566  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 explicit(_Not<_Lazy<_And, _IsImpDefault<_Tp>...> >::value)
567      tuple(allocator_arg_t, _Alloc const& __a)
568      : __base_(allocator_arg_t(),
569                __a,
570                __tuple_indices<>(),
571                __tuple_types<>(),
572                typename __make_tuple_indices<sizeof...(_Tp), 0>::type(),
573                __tuple_types<_Tp...>()) {}
574
575  // tuple(const T&...) constructors (including allocator_arg_t variants)
576  template <template <class...> class _And = _And,
577            __enable_if_t< _And< _BoolConstant<sizeof...(_Tp) >= 1>, is_copy_constructible<_Tp>... >::value, int> = 0>
578  _LIBCPP_HIDE_FROM_ABI
579  _LIBCPP_CONSTEXPR_SINCE_CXX14 explicit(_Not<_Lazy<_And, is_convertible<const _Tp&, _Tp>...> >::value)
580      tuple(const _Tp&... __t) noexcept(_And<is_nothrow_copy_constructible<_Tp>...>::value)
581      : __base_(typename __make_tuple_indices<sizeof...(_Tp)>::type(),
582                typename __make_tuple_types<tuple, sizeof...(_Tp)>::type(),
583                typename __make_tuple_indices<0>::type(),
584                typename __make_tuple_types<tuple, 0>::type(),
585                __t...) {}
586
587  template <class _Alloc,
588            template <class...> class _And = _And,
589            __enable_if_t< _And< _BoolConstant<sizeof...(_Tp) >= 1>, is_copy_constructible<_Tp>... >::value, int> = 0>
590  _LIBCPP_HIDE_FROM_ABI
591  _LIBCPP_CONSTEXPR_SINCE_CXX20 explicit(_Not<_Lazy<_And, is_convertible<const _Tp&, _Tp>...> >::value)
592      tuple(allocator_arg_t, const _Alloc& __a, const _Tp&... __t)
593      : __base_(allocator_arg_t(),
594                __a,
595                typename __make_tuple_indices<sizeof...(_Tp)>::type(),
596                typename __make_tuple_types<tuple, sizeof...(_Tp)>::type(),
597                typename __make_tuple_indices<0>::type(),
598                typename __make_tuple_types<tuple, 0>::type(),
599                __t...) {}
600
601  // tuple(U&& ...) constructors (including allocator_arg_t variants)
602  template <class... _Up>
603  struct _IsThisTuple : false_type {};
604  template <class _Up>
605  struct _IsThisTuple<_Up> : is_same<__remove_cvref_t<_Up>, tuple> {};
606
607  template <class... _Up>
608  struct _EnableUTypesCtor
609      : _And< _BoolConstant<sizeof...(_Tp) >= 1>,
610              _Not<_IsThisTuple<_Up...> >, // extension to allow mis-behaved user constructors
611              is_constructible<_Tp, _Up>... > {};
612
613  template <class... _Up,
614            __enable_if_t< _And< _BoolConstant<sizeof...(_Up) == sizeof...(_Tp)>, _EnableUTypesCtor<_Up...> >::value,
615                           int> = 0>
616  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 explicit(_Not<_Lazy<_And, is_convertible<_Up, _Tp>...> >::value)
617      tuple(_Up&&... __u) noexcept(_And<is_nothrow_constructible<_Tp, _Up>...>::value)
618      : __base_(typename __make_tuple_indices<sizeof...(_Up)>::type(),
619                typename __make_tuple_types<tuple, sizeof...(_Up)>::type(),
620                typename __make_tuple_indices<sizeof...(_Tp), sizeof...(_Up)>::type(),
621                typename __make_tuple_types<tuple, sizeof...(_Tp), sizeof...(_Up)>::type(),
622                std::forward<_Up>(__u)...) {}
623
624  template <class _Alloc,
625            class... _Up,
626            __enable_if_t< _And< _BoolConstant<sizeof...(_Up) == sizeof...(_Tp)>, _EnableUTypesCtor<_Up...> >::value,
627                           int> = 0>
628  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 explicit(_Not<_Lazy<_And, is_convertible<_Up, _Tp>...> >::value)
629      tuple(allocator_arg_t, const _Alloc& __a, _Up&&... __u)
630      : __base_(allocator_arg_t(),
631                __a,
632                typename __make_tuple_indices<sizeof...(_Up)>::type(),
633                typename __make_tuple_types<tuple, sizeof...(_Up)>::type(),
634                typename __make_tuple_indices<sizeof...(_Tp), sizeof...(_Up)>::type(),
635                typename __make_tuple_types<tuple, sizeof...(_Tp), sizeof...(_Up)>::type(),
636                std::forward<_Up>(__u)...) {}
637
638  // Copy and move constructors (including the allocator_arg_t variants)
639  tuple(const tuple&) = default;
640  tuple(tuple&&)      = default;
641
642  template <class _Alloc,
643            template <class...> class _And                                  = _And,
644            __enable_if_t< _And<is_copy_constructible<_Tp>...>::value, int> = 0>
645  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 tuple(allocator_arg_t, const _Alloc& __alloc, const tuple& __t)
646      : __base_(allocator_arg_t(), __alloc, __t) {}
647
648  template <class _Alloc,
649            template <class...> class _And                                  = _And,
650            __enable_if_t< _And<is_move_constructible<_Tp>...>::value, int> = 0>
651  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 tuple(allocator_arg_t, const _Alloc& __alloc, tuple&& __t)
652      : __base_(allocator_arg_t(), __alloc, std::move(__t)) {}
653
654  // tuple(const tuple<U...>&) constructors (including allocator_arg_t variants)
655
656  template <class _OtherTuple, class _DecayedOtherTuple = __remove_cvref_t<_OtherTuple>, class = void>
657  struct _EnableCtorFromUTypesTuple : false_type {};
658
659  template <class _OtherTuple, class... _Up>
660  struct _EnableCtorFromUTypesTuple<
661      _OtherTuple,
662      tuple<_Up...>,
663      // the length of the packs needs to checked first otherwise the 2 packs cannot be expanded simultaneously below
664      __enable_if_t<sizeof...(_Up) == sizeof...(_Tp)>>
665      : _And<
666            // the two conditions below are not in spec. The purpose is to disable the UTypes Ctor when copy/move Ctor
667            // can work. Otherwise, is_constructible can trigger hard error in those cases
668            // https://godbolt.org/z/M94cGdKcE
669            _Not<is_same<_OtherTuple, const tuple&> >,
670            _Not<is_same<_OtherTuple, tuple&&> >,
671            is_constructible<_Tp, __copy_cvref_t<_OtherTuple, _Up> >...,
672            _Lazy<_Or,
673                  _BoolConstant<sizeof...(_Tp) != 1>,
674                  // _Tp and _Up are 1-element packs - the pack expansions look
675                  // weird to avoid tripping up the type traits in degenerate cases
676                  _Lazy<_And,
677                        _Not<is_same<_Tp, _Up> >...,
678                        _Not<is_convertible<_OtherTuple, _Tp> >...,
679                        _Not<is_constructible<_Tp, _OtherTuple> >... > > > {};
680
681  template <class... _Up, __enable_if_t< _And< _EnableCtorFromUTypesTuple<const tuple<_Up...>&> >::value, int> = 0>
682  _LIBCPP_HIDE_FROM_ABI
683  _LIBCPP_CONSTEXPR_SINCE_CXX14 explicit(_Not<_Lazy<_And, is_convertible<const _Up&, _Tp>...> >::value)
684      tuple(const tuple<_Up...>& __t) noexcept(_And<is_nothrow_constructible<_Tp, const _Up&>...>::value)
685      : __base_(__t) {}
686
687  template <class... _Up,
688            class _Alloc,
689            __enable_if_t< _And< _EnableCtorFromUTypesTuple<const tuple<_Up...>&> >::value, int> = 0>
690  _LIBCPP_HIDE_FROM_ABI
691  _LIBCPP_CONSTEXPR_SINCE_CXX20 explicit(_Not<_Lazy<_And, is_convertible<const _Up&, _Tp>...> >::value)
692      tuple(allocator_arg_t, const _Alloc& __a, const tuple<_Up...>& __t)
693      : __base_(allocator_arg_t(), __a, __t) {}
694
695#  if _LIBCPP_STD_VER >= 23
696  // tuple(tuple<U...>&) constructors (including allocator_arg_t variants)
697
698  template <class... _Up, enable_if_t< _EnableCtorFromUTypesTuple<tuple<_Up...>&>::value>* = nullptr>
699  _LIBCPP_HIDE_FROM_ABI constexpr explicit(!_Lazy<_And, is_convertible<_Up&, _Tp>...>::value) tuple(tuple<_Up...>& __t)
700      : __base_(__t) {}
701
702  template <class _Alloc, class... _Up, enable_if_t< _EnableCtorFromUTypesTuple<tuple<_Up...>&>::value>* = nullptr>
703  _LIBCPP_HIDE_FROM_ABI constexpr explicit(!_Lazy<_And, is_convertible<_Up&, _Tp>...>::value)
704      tuple(allocator_arg_t, const _Alloc& __alloc, tuple<_Up...>& __t)
705      : __base_(allocator_arg_t(), __alloc, __t) {}
706#  endif // _LIBCPP_STD_VER >= 23
707
708  // tuple(tuple<U...>&&) constructors (including allocator_arg_t variants)
709  template <class... _Up, __enable_if_t< _And< _EnableCtorFromUTypesTuple<tuple<_Up...>&&> >::value, int> = 0>
710  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 explicit(_Not<_Lazy<_And, is_convertible<_Up, _Tp>...> >::value)
711      tuple(tuple<_Up...>&& __t) noexcept(_And<is_nothrow_constructible<_Tp, _Up>...>::value)
712      : __base_(std::move(__t)) {}
713
714  template <class _Alloc,
715            class... _Up,
716            __enable_if_t< _And< _EnableCtorFromUTypesTuple<tuple<_Up...>&&> >::value, int> = 0>
717  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 explicit(_Not<_Lazy<_And, is_convertible<_Up, _Tp>...> >::value)
718      tuple(allocator_arg_t, const _Alloc& __a, tuple<_Up...>&& __t)
719      : __base_(allocator_arg_t(), __a, std::move(__t)) {}
720
721#  if _LIBCPP_STD_VER >= 23
722  // tuple(const tuple<U...>&&) constructors (including allocator_arg_t variants)
723
724  template <class... _Up, enable_if_t< _EnableCtorFromUTypesTuple<const tuple<_Up...>&&>::value>* = nullptr>
725  _LIBCPP_HIDE_FROM_ABI constexpr explicit(!_Lazy<_And, is_convertible<const _Up&&, _Tp>...>::value)
726      tuple(const tuple<_Up...>&& __t)
727      : __base_(std::move(__t)) {}
728
729  template <class _Alloc,
730            class... _Up,
731            enable_if_t< _EnableCtorFromUTypesTuple<const tuple<_Up...>&&>::value>* = nullptr>
732  _LIBCPP_HIDE_FROM_ABI constexpr explicit(!_Lazy<_And, is_convertible<const _Up&&, _Tp>...>::value)
733      tuple(allocator_arg_t, const _Alloc& __alloc, const tuple<_Up...>&& __t)
734      : __base_(allocator_arg_t(), __alloc, std::move(__t)) {}
735#  endif // _LIBCPP_STD_VER >= 23
736
737  // tuple(const pair<U1, U2>&) constructors (including allocator_arg_t variants)
738
739  template <template <class...> class _Pred,
740            class _Pair,
741            class _DecayedPair = __remove_cvref_t<_Pair>,
742            class _Tuple       = tuple>
743  struct _CtorPredicateFromPair : false_type {};
744
745  template <template <class...> class _Pred, class _Pair, class _Up1, class _Up2, class _Tp1, class _Tp2>
746  struct _CtorPredicateFromPair<_Pred, _Pair, pair<_Up1, _Up2>, tuple<_Tp1, _Tp2> >
747      : _And< _Pred<_Tp1, __copy_cvref_t<_Pair, _Up1> >, _Pred<_Tp2, __copy_cvref_t<_Pair, _Up2> > > {};
748
749  template <class _Pair>
750  struct _EnableCtorFromPair : _CtorPredicateFromPair<is_constructible, _Pair> {};
751
752  template <class _Pair>
753  struct _NothrowConstructibleFromPair : _CtorPredicateFromPair<is_nothrow_constructible, _Pair> {};
754
755  template <class _Pair, class _DecayedPair = __remove_cvref_t<_Pair>, class _Tuple = tuple>
756  struct _BothImplicitlyConvertible : false_type {};
757
758  template <class _Pair, class _Up1, class _Up2, class _Tp1, class _Tp2>
759  struct _BothImplicitlyConvertible<_Pair, pair<_Up1, _Up2>, tuple<_Tp1, _Tp2> >
760      : _And< is_convertible<__copy_cvref_t<_Pair, _Up1>, _Tp1>, is_convertible<__copy_cvref_t<_Pair, _Up2>, _Tp2> > {};
761
762  template <class _Up1,
763            class _Up2,
764            template <class...> class _And                                                   = _And,
765            __enable_if_t< _And< _EnableCtorFromPair<const pair<_Up1, _Up2>&> >::value, int> = 0>
766  _LIBCPP_HIDE_FROM_ABI
767  _LIBCPP_CONSTEXPR_SINCE_CXX14 explicit(_Not<_BothImplicitlyConvertible<const pair<_Up1, _Up2>&> >::value)
768      tuple(const pair<_Up1, _Up2>& __p) noexcept(_NothrowConstructibleFromPair<const pair<_Up1, _Up2>&>::value)
769      : __base_(__p) {}
770
771  template <class _Alloc,
772            class _Up1,
773            class _Up2,
774            template <class...> class _And                                                   = _And,
775            __enable_if_t< _And< _EnableCtorFromPair<const pair<_Up1, _Up2>&> >::value, int> = 0>
776  _LIBCPP_HIDE_FROM_ABI
777  _LIBCPP_CONSTEXPR_SINCE_CXX20 explicit(_Not<_BothImplicitlyConvertible<const pair<_Up1, _Up2>&> >::value)
778      tuple(allocator_arg_t, const _Alloc& __a, const pair<_Up1, _Up2>& __p)
779      : __base_(allocator_arg_t(), __a, __p) {}
780
781#  if _LIBCPP_STD_VER >= 23
782  // tuple(pair<U1, U2>&) constructors (including allocator_arg_t variants)
783
784  template <class _U1, class _U2, enable_if_t< _EnableCtorFromPair<pair<_U1, _U2>&>::value>* = nullptr>
785  _LIBCPP_HIDE_FROM_ABI constexpr explicit(!_BothImplicitlyConvertible<pair<_U1, _U2>&>::value)
786      tuple(pair<_U1, _U2>& __p)
787      : __base_(__p) {}
788
789  template <class _Alloc,
790            class _U1,
791            class _U2,
792            enable_if_t< _EnableCtorFromPair<std::pair<_U1, _U2>&>::value>* = nullptr>
793  _LIBCPP_HIDE_FROM_ABI constexpr explicit(!_BothImplicitlyConvertible<pair<_U1, _U2>&>::value)
794      tuple(allocator_arg_t, const _Alloc& __alloc, pair<_U1, _U2>& __p)
795      : __base_(allocator_arg_t(), __alloc, __p) {}
796#  endif
797
798  // tuple(pair<U1, U2>&&) constructors (including allocator_arg_t variants)
799
800  template <class _Up1,
801            class _Up2,
802            template <class...> class _And                                              = _And,
803            __enable_if_t< _And< _EnableCtorFromPair<pair<_Up1, _Up2>&&> >::value, int> = 0>
804  _LIBCPP_HIDE_FROM_ABI
805  _LIBCPP_CONSTEXPR_SINCE_CXX14 explicit(_Not<_BothImplicitlyConvertible<pair<_Up1, _Up2>&&> >::value)
806      tuple(pair<_Up1, _Up2>&& __p) noexcept(_NothrowConstructibleFromPair<pair<_Up1, _Up2>&&>::value)
807      : __base_(std::move(__p)) {}
808
809  template <class _Alloc,
810            class _Up1,
811            class _Up2,
812            template <class...> class _And                                              = _And,
813            __enable_if_t< _And< _EnableCtorFromPair<pair<_Up1, _Up2>&&> >::value, int> = 0>
814  _LIBCPP_HIDE_FROM_ABI
815  _LIBCPP_CONSTEXPR_SINCE_CXX20 explicit(_Not<_BothImplicitlyConvertible<pair<_Up1, _Up2>&&> >::value)
816      tuple(allocator_arg_t, const _Alloc& __a, pair<_Up1, _Up2>&& __p)
817      : __base_(allocator_arg_t(), __a, std::move(__p)) {}
818
819#  if _LIBCPP_STD_VER >= 23
820  // tuple(const pair<U1, U2>&&) constructors (including allocator_arg_t variants)
821
822  template <class _U1, class _U2, enable_if_t< _EnableCtorFromPair<const pair<_U1, _U2>&&>::value>* = nullptr>
823  _LIBCPP_HIDE_FROM_ABI constexpr explicit(!_BothImplicitlyConvertible<const pair<_U1, _U2>&&>::value)
824      tuple(const pair<_U1, _U2>&& __p)
825      : __base_(std::move(__p)) {}
826
827  template <class _Alloc,
828            class _U1,
829            class _U2,
830            enable_if_t< _EnableCtorFromPair<const pair<_U1, _U2>&&>::value>* = nullptr>
831  _LIBCPP_HIDE_FROM_ABI constexpr explicit(!_BothImplicitlyConvertible<const pair<_U1, _U2>&&>::value)
832      tuple(allocator_arg_t, const _Alloc& __alloc, const pair<_U1, _U2>&& __p)
833      : __base_(allocator_arg_t(), __alloc, std::move(__p)) {}
834#  endif // _LIBCPP_STD_VER >= 23
835
836  // [tuple.assign]
837  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 tuple&
838  operator=(_If<_And<is_copy_assignable<_Tp>...>::value, tuple, __nat> const& __tuple)
839      noexcept(_And<is_nothrow_copy_assignable<_Tp>...>::value) {
840    std::__memberwise_copy_assign(*this, __tuple, typename __make_tuple_indices<sizeof...(_Tp)>::type());
841    return *this;
842  }
843
844#  if _LIBCPP_STD_VER >= 23
845  _LIBCPP_HIDE_FROM_ABI constexpr const tuple& operator=(tuple const& __tuple) const
846    requires(_And<is_copy_assignable<const _Tp>...>::value)
847  {
848    std::__memberwise_copy_assign(*this, __tuple, typename __make_tuple_indices<sizeof...(_Tp)>::type());
849    return *this;
850  }
851
852  _LIBCPP_HIDE_FROM_ABI constexpr const tuple& operator=(tuple&& __tuple) const
853    requires(_And<is_assignable<const _Tp&, _Tp>...>::value)
854  {
855    std::__memberwise_forward_assign(
856        *this, std::move(__tuple), __tuple_types<_Tp...>(), typename __make_tuple_indices<sizeof...(_Tp)>::type());
857    return *this;
858  }
859#  endif // _LIBCPP_STD_VER >= 23
860
861  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 tuple&
862  operator=(_If<_And<is_move_assignable<_Tp>...>::value, tuple, __nat>&& __tuple)
863      noexcept(_And<is_nothrow_move_assignable<_Tp>...>::value) {
864    std::__memberwise_forward_assign(
865        *this, std::move(__tuple), __tuple_types<_Tp...>(), typename __make_tuple_indices<sizeof...(_Tp)>::type());
866    return *this;
867  }
868
869  template <
870      class... _Up,
871      __enable_if_t< _And< _BoolConstant<sizeof...(_Tp) == sizeof...(_Up)>, is_assignable<_Tp&, _Up const&>... >::value,
872                     int> = 0>
873  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 tuple& operator=(tuple<_Up...> const& __tuple)
874      noexcept(_And<is_nothrow_assignable<_Tp&, _Up const&>...>::value) {
875    std::__memberwise_copy_assign(*this, __tuple, typename __make_tuple_indices<sizeof...(_Tp)>::type());
876    return *this;
877  }
878
879  template <class... _Up,
880            __enable_if_t< _And< _BoolConstant<sizeof...(_Tp) == sizeof...(_Up)>, is_assignable<_Tp&, _Up>... >::value,
881                           int> = 0>
882  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 tuple& operator=(tuple<_Up...>&& __tuple)
883      noexcept(_And<is_nothrow_assignable<_Tp&, _Up>...>::value) {
884    std::__memberwise_forward_assign(
885        *this, std::move(__tuple), __tuple_types<_Up...>(), typename __make_tuple_indices<sizeof...(_Tp)>::type());
886    return *this;
887  }
888
889#  if _LIBCPP_STD_VER >= 23
890  template <class... _UTypes,
891            enable_if_t< _And<_BoolConstant<sizeof...(_Tp) == sizeof...(_UTypes)>,
892                              is_assignable<const _Tp&, const _UTypes&>...>::value>* = nullptr>
893  _LIBCPP_HIDE_FROM_ABI constexpr const tuple& operator=(const tuple<_UTypes...>& __u) const {
894    std::__memberwise_copy_assign(*this, __u, typename __make_tuple_indices<sizeof...(_Tp)>::type());
895    return *this;
896  }
897
898  template <class... _UTypes,
899            enable_if_t< _And<_BoolConstant<sizeof...(_Tp) == sizeof...(_UTypes)>,
900                              is_assignable<const _Tp&, _UTypes>...>::value>* = nullptr>
901  _LIBCPP_HIDE_FROM_ABI constexpr const tuple& operator=(tuple<_UTypes...>&& __u) const {
902    std::__memberwise_forward_assign(
903        *this, __u, __tuple_types<_UTypes...>(), typename __make_tuple_indices<sizeof...(_Tp)>::type());
904    return *this;
905  }
906#  endif // _LIBCPP_STD_VER >= 23
907
908  template <template <class...> class _Pred,
909            bool _Const,
910            class _Pair,
911            class _DecayedPair = __remove_cvref_t<_Pair>,
912            class _Tuple       = tuple>
913  struct _AssignPredicateFromPair : false_type {};
914
915  template <template <class...> class _Pred, bool _Const, class _Pair, class _Up1, class _Up2, class _Tp1, class _Tp2>
916  struct _AssignPredicateFromPair<_Pred, _Const, _Pair, pair<_Up1, _Up2>, tuple<_Tp1, _Tp2> >
917      : _And<_Pred<__maybe_const<_Const, _Tp1>&, __copy_cvref_t<_Pair, _Up1> >,
918             _Pred<__maybe_const<_Const, _Tp2>&, __copy_cvref_t<_Pair, _Up2> > > {};
919
920  template <bool _Const, class _Pair>
921  struct _EnableAssignFromPair : _AssignPredicateFromPair<is_assignable, _Const, _Pair> {};
922
923  template <bool _Const, class _Pair>
924  struct _NothrowAssignFromPair : _AssignPredicateFromPair<is_nothrow_assignable, _Const, _Pair> {};
925
926#  if _LIBCPP_STD_VER >= 23
927  template <class _U1, class _U2, enable_if_t< _EnableAssignFromPair<true, const pair<_U1, _U2>&>::value>* = nullptr>
928  _LIBCPP_HIDE_FROM_ABI constexpr const tuple& operator=(const pair<_U1, _U2>& __pair) const
929      noexcept(_NothrowAssignFromPair<true, const pair<_U1, _U2>&>::value) {
930    std::get<0>(*this) = __pair.first;
931    std::get<1>(*this) = __pair.second;
932    return *this;
933  }
934
935  template <class _U1, class _U2, enable_if_t< _EnableAssignFromPair<true, pair<_U1, _U2>&&>::value>* = nullptr>
936  _LIBCPP_HIDE_FROM_ABI constexpr const tuple& operator=(pair<_U1, _U2>&& __pair) const
937      noexcept(_NothrowAssignFromPair<true, pair<_U1, _U2>&&>::value) {
938    std::get<0>(*this) = std::move(__pair.first);
939    std::get<1>(*this) = std::move(__pair.second);
940    return *this;
941  }
942#  endif // _LIBCPP_STD_VER >= 23
943
944  template <class _Up1,
945            class _Up2,
946            __enable_if_t< _EnableAssignFromPair<false, pair<_Up1, _Up2> const&>::value, int> = 0>
947  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 tuple& operator=(pair<_Up1, _Up2> const& __pair)
948      noexcept(_NothrowAssignFromPair<false, pair<_Up1, _Up2> const&>::value) {
949    std::get<0>(*this) = __pair.first;
950    std::get<1>(*this) = __pair.second;
951    return *this;
952  }
953
954  template <class _Up1, class _Up2, __enable_if_t< _EnableAssignFromPair<false, pair<_Up1, _Up2>&&>::value, int> = 0>
955  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 tuple& operator=(pair<_Up1, _Up2>&& __pair)
956      noexcept(_NothrowAssignFromPair<false, pair<_Up1, _Up2>&&>::value) {
957    std::get<0>(*this) = std::forward<_Up1>(__pair.first);
958    std::get<1>(*this) = std::forward<_Up2>(__pair.second);
959    return *this;
960  }
961
962  // EXTENSION
963  template <
964      class _Up,
965      size_t _Np,
966      __enable_if_t< _And< _BoolConstant<_Np == sizeof...(_Tp)>, is_assignable<_Tp&, _Up const&>... >::value, int> = 0>
967  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 tuple& operator=(array<_Up, _Np> const& __array)
968      noexcept(_And<is_nothrow_assignable<_Tp&, _Up const&>...>::value) {
969    std::__memberwise_copy_assign(*this, __array, typename __make_tuple_indices<sizeof...(_Tp)>::type());
970    return *this;
971  }
972
973  // EXTENSION
974  template <class _Up,
975            size_t _Np,
976            class = void,
977            __enable_if_t< _And< _BoolConstant<_Np == sizeof...(_Tp)>, is_assignable<_Tp&, _Up>... >::value, int> = 0>
978  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 tuple& operator=(array<_Up, _Np>&& __array)
979      noexcept(_And<is_nothrow_assignable<_Tp&, _Up>...>::value) {
980    std::__memberwise_forward_assign(
981        *this,
982        std::move(__array),
983        __tuple_types<_If<true, _Up, _Tp>...>(),
984        typename __make_tuple_indices<sizeof...(_Tp)>::type());
985    return *this;
986  }
987
988  // [tuple.swap]
989  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 void swap(tuple& __t)
990      noexcept(__all<__is_nothrow_swappable_v<_Tp>...>::value) {
991    __base_.swap(__t.__base_);
992  }
993
994#  if _LIBCPP_STD_VER >= 23
995  _LIBCPP_HIDE_FROM_ABI constexpr void swap(const tuple& __t) const
996      noexcept(__all<is_nothrow_swappable_v<const _Tp&>...>::value) {
997    __base_.swap(__t.__base_);
998  }
999#  endif // _LIBCPP_STD_VER >= 23
1000};
1001
1002template <>
1003class _LIBCPP_TEMPLATE_VIS tuple<> {
1004public:
1005  constexpr tuple() _NOEXCEPT = default;
1006  template <class _Alloc>
1007  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 tuple(allocator_arg_t, const _Alloc&) _NOEXCEPT {}
1008  template <class _Alloc>
1009  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 tuple(allocator_arg_t, const _Alloc&, const tuple&) _NOEXCEPT {}
1010  template <class _Up>
1011  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 tuple(array<_Up, 0>) _NOEXCEPT {}
1012  template <class _Alloc, class _Up>
1013  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 tuple(allocator_arg_t, const _Alloc&, array<_Up, 0>) _NOEXCEPT {}
1014  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 void swap(tuple&) _NOEXCEPT {}
1015#  if _LIBCPP_STD_VER >= 23
1016  _LIBCPP_HIDE_FROM_ABI constexpr void swap(const tuple&) const noexcept {}
1017#  endif
1018};
1019
1020#  if _LIBCPP_STD_VER >= 23
1021template <class... _TTypes, class... _UTypes, template <class> class _TQual, template <class> class _UQual>
1022  requires requires { typename tuple<common_reference_t<_TQual<_TTypes>, _UQual<_UTypes>>...>; }
1023struct basic_common_reference<tuple<_TTypes...>, tuple<_UTypes...>, _TQual, _UQual> {
1024  using type = tuple<common_reference_t<_TQual<_TTypes>, _UQual<_UTypes>>...>;
1025};
1026
1027template <class... _TTypes, class... _UTypes>
1028  requires requires { typename tuple<common_type_t<_TTypes, _UTypes>...>; }
1029struct common_type<tuple<_TTypes...>, tuple<_UTypes...>> {
1030  using type = tuple<common_type_t<_TTypes, _UTypes>...>;
1031};
1032#  endif // _LIBCPP_STD_VER >= 23
1033
1034#  if _LIBCPP_STD_VER >= 17
1035template <class... _Tp>
1036tuple(_Tp...) -> tuple<_Tp...>;
1037template <class _Tp1, class _Tp2>
1038tuple(pair<_Tp1, _Tp2>) -> tuple<_Tp1, _Tp2>;
1039template <class _Alloc, class... _Tp>
1040tuple(allocator_arg_t, _Alloc, _Tp...) -> tuple<_Tp...>;
1041template <class _Alloc, class _Tp1, class _Tp2>
1042tuple(allocator_arg_t, _Alloc, pair<_Tp1, _Tp2>) -> tuple<_Tp1, _Tp2>;
1043template <class _Alloc, class... _Tp>
1044tuple(allocator_arg_t, _Alloc, tuple<_Tp...>) -> tuple<_Tp...>;
1045#  endif
1046
1047template <class... _Tp, __enable_if_t<__all<__is_swappable_v<_Tp>...>::value, int> = 0>
1048inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 void swap(tuple<_Tp...>& __t, tuple<_Tp...>& __u)
1049    noexcept(__all<__is_nothrow_swappable_v<_Tp>...>::value) {
1050  __t.swap(__u);
1051}
1052
1053#  if _LIBCPP_STD_VER >= 23
1054template <class... _Tp>
1055_LIBCPP_HIDE_FROM_ABI constexpr enable_if_t<__all<is_swappable_v<const _Tp>...>::value, void>
1056swap(const tuple<_Tp...>& __lhs,
1057     const tuple<_Tp...>& __rhs) noexcept(__all<is_nothrow_swappable_v<const _Tp>...>::value) {
1058  __lhs.swap(__rhs);
1059}
1060#  endif
1061
1062// get
1063
1064template <size_t _Ip, class... _Tp>
1065inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 typename tuple_element<_Ip, tuple<_Tp...> >::type&
1066get(tuple<_Tp...>& __t) _NOEXCEPT {
1067  typedef _LIBCPP_NODEBUG typename tuple_element<_Ip, tuple<_Tp...> >::type type;
1068  return static_cast<__tuple_leaf<_Ip, type>&>(__t.__base_).get();
1069}
1070
1071template <size_t _Ip, class... _Tp>
1072inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 const typename tuple_element<_Ip, tuple<_Tp...> >::type&
1073get(const tuple<_Tp...>& __t) _NOEXCEPT {
1074  typedef _LIBCPP_NODEBUG typename tuple_element<_Ip, tuple<_Tp...> >::type type;
1075  return static_cast<const __tuple_leaf<_Ip, type>&>(__t.__base_).get();
1076}
1077
1078template <size_t _Ip, class... _Tp>
1079inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 typename tuple_element<_Ip, tuple<_Tp...> >::type&&
1080get(tuple<_Tp...>&& __t) _NOEXCEPT {
1081  typedef _LIBCPP_NODEBUG typename tuple_element<_Ip, tuple<_Tp...> >::type type;
1082  return static_cast<type&&>(static_cast<__tuple_leaf<_Ip, type>&&>(__t.__base_).get());
1083}
1084
1085template <size_t _Ip, class... _Tp>
1086inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 const typename tuple_element<_Ip, tuple<_Tp...> >::type&&
1087get(const tuple<_Tp...>&& __t) _NOEXCEPT {
1088  typedef _LIBCPP_NODEBUG typename tuple_element<_Ip, tuple<_Tp...> >::type type;
1089  return static_cast<const type&&>(static_cast<const __tuple_leaf<_Ip, type>&&>(__t.__base_).get());
1090}
1091
1092#  if _LIBCPP_STD_VER >= 14
1093
1094template <class _T1, class... _Args>
1095inline _LIBCPP_HIDE_FROM_ABI constexpr _T1& get(tuple<_Args...>& __tup) noexcept {
1096  return std::get<__find_exactly_one_t<_T1, _Args...>::value>(__tup);
1097}
1098
1099template <class _T1, class... _Args>
1100inline _LIBCPP_HIDE_FROM_ABI constexpr _T1 const& get(tuple<_Args...> const& __tup) noexcept {
1101  return std::get<__find_exactly_one_t<_T1, _Args...>::value>(__tup);
1102}
1103
1104template <class _T1, class... _Args>
1105inline _LIBCPP_HIDE_FROM_ABI constexpr _T1&& get(tuple<_Args...>&& __tup) noexcept {
1106  return std::get<__find_exactly_one_t<_T1, _Args...>::value>(std::move(__tup));
1107}
1108
1109template <class _T1, class... _Args>
1110inline _LIBCPP_HIDE_FROM_ABI constexpr _T1 const&& get(tuple<_Args...> const&& __tup) noexcept {
1111  return std::get<__find_exactly_one_t<_T1, _Args...>::value>(std::move(__tup));
1112}
1113
1114#  endif
1115
1116// tie
1117
1118template <class... _Tp>
1119inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 tuple<_Tp&...> tie(_Tp&... __t) _NOEXCEPT {
1120  return tuple<_Tp&...>(__t...);
1121}
1122
1123template <class... _Tp>
1124inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 tuple<typename __unwrap_ref_decay<_Tp>::type...>
1125make_tuple(_Tp&&... __t) {
1126  return tuple<typename __unwrap_ref_decay<_Tp>::type...>(std::forward<_Tp>(__t)...);
1127}
1128
1129template <class... _Tp>
1130inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 tuple<_Tp&&...> forward_as_tuple(_Tp&&... __t) _NOEXCEPT {
1131  return tuple<_Tp&&...>(std::forward<_Tp>(__t)...);
1132}
1133
1134template <size_t _Ip>
1135struct __tuple_equal {
1136  template <class _Tp, class _Up>
1137  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 bool operator()(const _Tp& __x, const _Up& __y) {
1138    return __tuple_equal<_Ip - 1>()(__x, __y) && std::get<_Ip - 1>(__x) == std::get<_Ip - 1>(__y);
1139  }
1140};
1141
1142template <>
1143struct __tuple_equal<0> {
1144  template <class _Tp, class _Up>
1145  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 bool operator()(const _Tp&, const _Up&) {
1146    return true;
1147  }
1148};
1149
1150template <class... _Tp, class... _Up>
1151inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 bool
1152operator==(const tuple<_Tp...>& __x, const tuple<_Up...>& __y) {
1153  static_assert(sizeof...(_Tp) == sizeof...(_Up), "Can't compare tuples of different sizes");
1154  return __tuple_equal<sizeof...(_Tp)>()(__x, __y);
1155}
1156
1157#  if _LIBCPP_STD_VER >= 20
1158
1159// operator<=>
1160
1161template <class... _Tp, class... _Up, size_t... _Is>
1162_LIBCPP_HIDE_FROM_ABI constexpr auto
1163__tuple_compare_three_way(const tuple<_Tp...>& __x, const tuple<_Up...>& __y, index_sequence<_Is...>) {
1164  common_comparison_category_t<__synth_three_way_result<_Tp, _Up>...> __result = strong_ordering::equal;
1165  static_cast<void>(
1166      ((__result = std::__synth_three_way(std::get<_Is>(__x), std::get<_Is>(__y)), __result != 0) || ...));
1167  return __result;
1168}
1169
1170template <class... _Tp, class... _Up>
1171  requires(sizeof...(_Tp) == sizeof...(_Up))
1172_LIBCPP_HIDE_FROM_ABI constexpr common_comparison_category_t<__synth_three_way_result<_Tp, _Up>...>
1173operator<=>(const tuple<_Tp...>& __x, const tuple<_Up...>& __y) {
1174  return std::__tuple_compare_three_way(__x, __y, index_sequence_for<_Tp...>{});
1175}
1176
1177#  else // _LIBCPP_STD_VER >= 20
1178
1179template <class... _Tp, class... _Up>
1180inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 bool
1181operator!=(const tuple<_Tp...>& __x, const tuple<_Up...>& __y) {
1182  return !(__x == __y);
1183}
1184
1185template <size_t _Ip>
1186struct __tuple_less {
1187  template <class _Tp, class _Up>
1188  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 bool operator()(const _Tp& __x, const _Up& __y) {
1189    const size_t __idx = tuple_size<_Tp>::value - _Ip;
1190    if (std::get<__idx>(__x) < std::get<__idx>(__y))
1191      return true;
1192    if (std::get<__idx>(__y) < std::get<__idx>(__x))
1193      return false;
1194    return __tuple_less<_Ip - 1>()(__x, __y);
1195  }
1196};
1197
1198template <>
1199struct __tuple_less<0> {
1200  template <class _Tp, class _Up>
1201  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 bool operator()(const _Tp&, const _Up&) {
1202    return false;
1203  }
1204};
1205
1206template <class... _Tp, class... _Up>
1207inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 bool
1208operator<(const tuple<_Tp...>& __x, const tuple<_Up...>& __y) {
1209  static_assert(sizeof...(_Tp) == sizeof...(_Up), "Can't compare tuples of different sizes");
1210  return __tuple_less<sizeof...(_Tp)>()(__x, __y);
1211}
1212
1213template <class... _Tp, class... _Up>
1214inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 bool
1215operator>(const tuple<_Tp...>& __x, const tuple<_Up...>& __y) {
1216  return __y < __x;
1217}
1218
1219template <class... _Tp, class... _Up>
1220inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 bool
1221operator>=(const tuple<_Tp...>& __x, const tuple<_Up...>& __y) {
1222  return !(__x < __y);
1223}
1224
1225template <class... _Tp, class... _Up>
1226inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 bool
1227operator<=(const tuple<_Tp...>& __x, const tuple<_Up...>& __y) {
1228  return !(__y < __x);
1229}
1230
1231#  endif // _LIBCPP_STD_VER >= 20
1232
1233// tuple_cat
1234
1235template <class _Tp, class _Up>
1236struct __tuple_cat_type;
1237
1238template <class... _Ttypes, class... _Utypes>
1239struct __tuple_cat_type<tuple<_Ttypes...>, __tuple_types<_Utypes...> > {
1240  typedef _LIBCPP_NODEBUG tuple<_Ttypes..., _Utypes...> type;
1241};
1242
1243template <class _ResultTuple, bool _Is_Tuple0TupleLike, class... _Tuples>
1244struct __tuple_cat_return_1 {};
1245
1246template <class... _Types, class _Tuple0>
1247struct __tuple_cat_return_1<tuple<_Types...>, true, _Tuple0> {
1248  using type _LIBCPP_NODEBUG =
1249      typename __tuple_cat_type< tuple<_Types...>,
1250                                 typename __make_tuple_types<__remove_cvref_t<_Tuple0> >::type >::type;
1251};
1252
1253template <class... _Types, class _Tuple0, class _Tuple1, class... _Tuples>
1254struct __tuple_cat_return_1<tuple<_Types...>, true, _Tuple0, _Tuple1, _Tuples...>
1255    : public __tuple_cat_return_1<
1256          typename __tuple_cat_type< tuple<_Types...>,
1257                                     typename __make_tuple_types<__remove_cvref_t<_Tuple0> >::type >::type,
1258          __tuple_like_ext<__libcpp_remove_reference_t<_Tuple1> >::value,
1259          _Tuple1,
1260          _Tuples...> {};
1261
1262template <class... _Tuples>
1263struct __tuple_cat_return;
1264
1265template <class _Tuple0, class... _Tuples>
1266struct __tuple_cat_return<_Tuple0, _Tuples...>
1267    : public __tuple_cat_return_1<tuple<>,
1268                                  __tuple_like_ext<__libcpp_remove_reference_t<_Tuple0> >::value,
1269                                  _Tuple0,
1270                                  _Tuples...> {};
1271
1272template <>
1273struct __tuple_cat_return<> {
1274  typedef _LIBCPP_NODEBUG tuple<> type;
1275};
1276
1277inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 tuple<> tuple_cat() { return tuple<>(); }
1278
1279template <class _Rp, class _Indices, class _Tuple0, class... _Tuples>
1280struct __tuple_cat_return_ref_imp;
1281
1282template <class... _Types, size_t... _I0, class _Tuple0>
1283struct __tuple_cat_return_ref_imp<tuple<_Types...>, __tuple_indices<_I0...>, _Tuple0> {
1284  typedef _LIBCPP_NODEBUG __libcpp_remove_reference_t<_Tuple0> _T0;
1285  typedef tuple<_Types..., __copy_cvref_t<_Tuple0, typename tuple_element<_I0, _T0>::type>&&...> type;
1286};
1287
1288template <class... _Types, size_t... _I0, class _Tuple0, class _Tuple1, class... _Tuples>
1289struct __tuple_cat_return_ref_imp<tuple<_Types...>, __tuple_indices<_I0...>, _Tuple0, _Tuple1, _Tuples...>
1290    : public __tuple_cat_return_ref_imp<
1291          tuple<_Types...,
1292                __copy_cvref_t<_Tuple0, typename tuple_element<_I0, __libcpp_remove_reference_t<_Tuple0>>::type>&&...>,
1293          typename __make_tuple_indices<tuple_size<__libcpp_remove_reference_t<_Tuple1> >::value>::type,
1294          _Tuple1,
1295          _Tuples...> {};
1296
1297template <class _Tuple0, class... _Tuples>
1298struct __tuple_cat_return_ref
1299    : public __tuple_cat_return_ref_imp<
1300          tuple<>,
1301          typename __make_tuple_indices< tuple_size<__libcpp_remove_reference_t<_Tuple0> >::value >::type,
1302          _Tuple0,
1303          _Tuples...> {};
1304
1305template <class _Types, class _I0, class _J0>
1306struct __tuple_cat;
1307
1308template <class... _Types, size_t... _I0, size_t... _J0>
1309struct __tuple_cat<tuple<_Types...>, __tuple_indices<_I0...>, __tuple_indices<_J0...> > {
1310  template <class _Tuple0>
1311  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14
1312  typename __tuple_cat_return_ref<tuple<_Types...>&&, _Tuple0&&>::type
1313  operator()(tuple<_Types...> __t, _Tuple0&& __t0) {
1314    (void)__t; // avoid unused parameter warning on GCC when _I0 is empty
1315    return std::forward_as_tuple(
1316        std::forward<_Types>(std::get<_I0>(__t))..., std::get<_J0>(std::forward<_Tuple0>(__t0))...);
1317  }
1318
1319  template <class _Tuple0, class _Tuple1, class... _Tuples>
1320  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14
1321  typename __tuple_cat_return_ref<tuple<_Types...>&&, _Tuple0&&, _Tuple1&&, _Tuples&&...>::type
1322  operator()(tuple<_Types...> __t, _Tuple0&& __t0, _Tuple1&& __t1, _Tuples&&... __tpls) {
1323    (void)__t; // avoid unused parameter warning on GCC when _I0 is empty
1324    typedef _LIBCPP_NODEBUG __libcpp_remove_reference_t<_Tuple0> _T0;
1325    typedef _LIBCPP_NODEBUG __libcpp_remove_reference_t<_Tuple1> _T1;
1326    return __tuple_cat<tuple<_Types..., __copy_cvref_t<_Tuple0, typename tuple_element<_J0, _T0>::type>&&...>,
1327                       typename __make_tuple_indices<sizeof...(_Types) + tuple_size<_T0>::value>::type,
1328                       typename __make_tuple_indices<tuple_size<_T1>::value>::type>()(
1329        std::forward_as_tuple(
1330            std::forward<_Types>(std::get<_I0>(__t))..., std::get<_J0>(std::forward<_Tuple0>(__t0))...),
1331        std::forward<_Tuple1>(__t1),
1332        std::forward<_Tuples>(__tpls)...);
1333  }
1334};
1335
1336template <class _Tuple0, class... _Tuples>
1337inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 typename __tuple_cat_return<_Tuple0, _Tuples...>::type
1338tuple_cat(_Tuple0&& __t0, _Tuples&&... __tpls) {
1339  typedef _LIBCPP_NODEBUG __libcpp_remove_reference_t<_Tuple0> _T0;
1340  return __tuple_cat<tuple<>, __tuple_indices<>, typename __make_tuple_indices<tuple_size<_T0>::value>::type>()(
1341      tuple<>(), std::forward<_Tuple0>(__t0), std::forward<_Tuples>(__tpls)...);
1342}
1343
1344template <class... _Tp, class _Alloc>
1345struct _LIBCPP_TEMPLATE_VIS uses_allocator<tuple<_Tp...>, _Alloc> : true_type {};
1346
1347#  if _LIBCPP_STD_VER >= 17
1348#    define _LIBCPP_NOEXCEPT_RETURN(...)                                                                               \
1349      noexcept(noexcept(__VA_ARGS__)) { return __VA_ARGS__; }
1350
1351// The _LIBCPP_NOEXCEPT_RETURN macro breaks formatting.
1352// clang-format off
1353template <class _Fn, class _Tuple, size_t... _Id>
1354inline _LIBCPP_HIDE_FROM_ABI constexpr decltype(auto)
1355__apply_tuple_impl(_Fn&& __f, _Tuple&& __t, __tuple_indices<_Id...>)
1356    _LIBCPP_NOEXCEPT_RETURN(std::__invoke(std::forward<_Fn>(__f), std::get<_Id>(std::forward<_Tuple>(__t))...))
1357
1358template <class _Fn, class _Tuple>
1359inline _LIBCPP_HIDE_FROM_ABI constexpr decltype(auto) apply(_Fn&& __f, _Tuple&& __t)
1360    _LIBCPP_NOEXCEPT_RETURN(std::__apply_tuple_impl(
1361        std::forward<_Fn>(__f),
1362        std::forward<_Tuple>(__t),
1363        typename __make_tuple_indices<tuple_size_v<remove_reference_t<_Tuple>>>::type{}))
1364
1365#if _LIBCPP_STD_VER >= 20
1366template <class _Tp, class _Tuple, size_t... _Idx>
1367inline _LIBCPP_HIDE_FROM_ABI constexpr _Tp __make_from_tuple_impl(_Tuple&& __t, __tuple_indices<_Idx...>)
1368  noexcept(noexcept(_Tp(std::get<_Idx>(std::forward<_Tuple>(__t))...)))
1369  requires is_constructible_v<_Tp, decltype(std::get<_Idx>(std::forward<_Tuple>(__t)))...> {
1370  return _Tp(std::get<_Idx>(std::forward<_Tuple>(__t))...);
1371}
1372#else
1373template <class _Tp, class _Tuple, size_t... _Idx>
1374inline _LIBCPP_HIDE_FROM_ABI constexpr _Tp __make_from_tuple_impl(_Tuple&& __t, __tuple_indices<_Idx...>,
1375    enable_if_t<is_constructible_v<_Tp, decltype(std::get<_Idx>(std::forward<_Tuple>(__t)))...>> * = nullptr)
1376    _LIBCPP_NOEXCEPT_RETURN(_Tp(std::get<_Idx>(std::forward<_Tuple>(__t))...))
1377#endif // _LIBCPP_STD_VER >= 20
1378
1379template <class _Tp, class _Tuple,
1380          class _Seq = typename __make_tuple_indices<tuple_size_v<remove_reference_t<_Tuple>>>::type, class = void>
1381inline constexpr bool __can_make_from_tuple = false;
1382
1383template <class _Tp, class _Tuple, size_t... _Idx>
1384inline constexpr bool __can_make_from_tuple<_Tp, _Tuple, __tuple_indices<_Idx...>,
1385    enable_if_t<is_constructible_v<_Tp, decltype(std::get<_Idx>(std::declval<_Tuple>()))...>>> = true;
1386
1387// Based on LWG3528(https://wg21.link/LWG3528) and http://eel.is/c++draft/description#structure.requirements-9,
1388// the standard allows to impose requirements, we constraint std::make_from_tuple to make std::make_from_tuple
1389// SFINAE friendly and also avoid worse diagnostic messages. We still keep the constraints of std::__make_from_tuple_impl
1390// so that std::__make_from_tuple_impl will have the same advantages when used alone.
1391#if _LIBCPP_STD_VER >= 20
1392template <class _Tp, class _Tuple>
1393  requires __can_make_from_tuple<_Tp, _Tuple> // strengthen
1394#else
1395template <class _Tp, class _Tuple, class = enable_if_t<__can_make_from_tuple<_Tp, _Tuple>>> // strengthen
1396#endif // _LIBCPP_STD_VER >= 20
1397inline _LIBCPP_HIDE_FROM_ABI constexpr _Tp make_from_tuple(_Tuple&& __t)
1398    _LIBCPP_NOEXCEPT_RETURN(std::__make_from_tuple_impl<_Tp>(
1399        std::forward<_Tuple>(__t), typename __make_tuple_indices<tuple_size_v<remove_reference_t<_Tuple>>>::type{}))
1400#    undef _LIBCPP_NOEXCEPT_RETURN
1401
1402#  endif // _LIBCPP_STD_VER >= 17
1403
1404#endif // !defined(_LIBCPP_CXX03_LANG)
1405
1406_LIBCPP_END_NAMESPACE_STD
1407
1408_LIBCPP_POP_MACROS
1409
1410// clang-format on
1411
1412#if !defined(_LIBCPP_REMOVE_TRANSITIVE_INCLUDES) && _LIBCPP_STD_VER <= 20
1413#  include <exception>
1414#  include <iosfwd>
1415#  include <new>
1416#  include <type_traits>
1417#  include <typeinfo>
1418#  include <utility>
1419#endif
1420
1421#endif // _LIBCPP_TUPLE
1422