3// Copyright (C) 2007-2025 Free Software Foundation, Inc.
5// This file is part of the GNU ISO C++ Library. This library is free
6// software; you can redistribute it and/or modify it under the
7// terms of the GNU General Public License as published by the
8// Free Software Foundation; either version 3, or (at your option)
11// This library is distributed in the hope that it will be useful,
12// but WITHOUT ANY WARRANTY; without even the implied warranty of
13// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14// GNU General Public License for more details.
16// Under Section 7 of GPL version 3, you are granted additional
17// permissions described in the GCC Runtime Library Exception, version
18// 3.1, as published by the Free Software Foundation.
20// You should have received a copy of the GNU General Public License and
21// a copy of the GCC Runtime Library Exception along with this program;
22// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
23// <http://www.gnu.org/licenses/>.
25/** @file include/tuple
26 * This is a Standard C++ Library header.
30#define _GLIBCXX_TUPLE 1
33#pragma GCC system_header
36#if __cplusplus < 201103L
37# include <bits/c++0x_warning.h>
40#include <bits/stl_pair.h> // for std::pair
41#include <bits/uses_allocator.h> // for std::allocator_arg_t
42#include <bits/utility.h> // for std::tuple_size etc.
43#include <bits/invoke.h> // for std::__invoke
44#if __cplusplus > 201703L
46# include <bits/ranges_util.h> // for std::ranges::subrange
49#define __glibcxx_want_constexpr_tuple
50#define __glibcxx_want_tuple_element_t
51#define __glibcxx_want_tuples_by_type
52#define __glibcxx_want_apply
53#define __glibcxx_want_make_from_tuple
54#define __glibcxx_want_ranges_zip
55#define __glibcxx_want_tuple_like
56#define __glibcxx_want_constrained_equality
57#include <bits/version.h>
59namespace std _GLIBCXX_VISIBILITY(default)
61_GLIBCXX_BEGIN_NAMESPACE_VERSION
64 * @addtogroup utilities
68 template<typename... _Elements>
71 /// @cond undocumented
72 template<typename _Tp>
73 struct __is_empty_non_tuple : is_empty<_Tp> { };
75 // Using EBO for elements that are tuples causes ambiguous base errors.
76 template<typename _El0, typename... _El>
77 struct __is_empty_non_tuple<tuple<_El0, _El...>> : false_type { };
79 // Use the Empty Base-class Optimization for empty, non-final types.
80 template<typename _Tp>
81 using __empty_not_final
82 = __conditional_t<__is_final(_Tp), false_type,
83 __is_empty_non_tuple<_Tp>>;
85 template<size_t _Idx, typename _Head,
86 bool = __empty_not_final<_Head>::value>
89#if __has_cpp_attribute(__no_unique_address__)
90 template<size_t _Idx, typename _Head>
91 struct _Head_base<_Idx, _Head, true>
93 constexpr _Head_base()
96 constexpr _Head_base(const _Head& __h)
97 : _M_head_impl(__h) { }
99 constexpr _Head_base(const _Head_base&) = default;
100 constexpr _Head_base(_Head_base&&) = default;
102 template<typename _UHead>
103 constexpr _Head_base(_UHead&& __h)
104 : _M_head_impl(std::forward<_UHead>(__h)) { }
107 _Head_base(allocator_arg_t, __uses_alloc0)
110 template<typename _Alloc>
112 _Head_base(allocator_arg_t, __uses_alloc1<_Alloc> __a)
113 : _M_head_impl(allocator_arg, *__a._M_a) { }
115 template<typename _Alloc>
117 _Head_base(allocator_arg_t, __uses_alloc2<_Alloc> __a)
118 : _M_head_impl(*__a._M_a) { }
120 template<typename _UHead>
122 _Head_base(__uses_alloc0, _UHead&& __uhead)
123 : _M_head_impl(std::forward<_UHead>(__uhead)) { }
125 template<typename _Alloc, typename _UHead>
127 _Head_base(__uses_alloc1<_Alloc> __a, _UHead&& __uhead)
128 : _M_head_impl(allocator_arg, *__a._M_a, std::forward<_UHead>(__uhead))
131 template<typename _Alloc, typename _UHead>
133 _Head_base(__uses_alloc2<_Alloc> __a, _UHead&& __uhead)
134 : _M_head_impl(std::forward<_UHead>(__uhead), *__a._M_a) { }
136 static constexpr _Head&
137 _M_head(_Head_base& __b) noexcept { return __b._M_head_impl; }
139 static constexpr const _Head&
140 _M_head(const _Head_base& __b) noexcept { return __b._M_head_impl; }
142 [[__no_unique_address__]] _Head _M_head_impl;
145 template<size_t _Idx, typename _Head>
146 struct _Head_base<_Idx, _Head, true>
149 constexpr _Head_base()
152 constexpr _Head_base(const _Head& __h)
155 constexpr _Head_base(const _Head_base&) = default;
156 constexpr _Head_base(_Head_base&&) = default;
158 template<typename _UHead>
159 constexpr _Head_base(_UHead&& __h)
160 : _Head(std::forward<_UHead>(__h)) { }
163 _Head_base(allocator_arg_t, __uses_alloc0)
166 template<typename _Alloc>
168 _Head_base(allocator_arg_t, __uses_alloc1<_Alloc> __a)
169 : _Head(allocator_arg, *__a._M_a) { }
171 template<typename _Alloc>
173 _Head_base(allocator_arg_t, __uses_alloc2<_Alloc> __a)
174 : _Head(*__a._M_a) { }
176 template<typename _UHead>
178 _Head_base(__uses_alloc0, _UHead&& __uhead)
179 : _Head(std::forward<_UHead>(__uhead)) { }
181 template<typename _Alloc, typename _UHead>
183 _Head_base(__uses_alloc1<_Alloc> __a, _UHead&& __uhead)
184 : _Head(allocator_arg, *__a._M_a, std::forward<_UHead>(__uhead)) { }
186 template<typename _Alloc, typename _UHead>
188 _Head_base(__uses_alloc2<_Alloc> __a, _UHead&& __uhead)
189 : _Head(std::forward<_UHead>(__uhead), *__a._M_a) { }
191 static constexpr _Head&
192 _M_head(_Head_base& __b) noexcept { return __b; }
194 static constexpr const _Head&
195 _M_head(const _Head_base& __b) noexcept { return __b; }
199 template<size_t _Idx, typename _Head>
200 struct _Head_base<_Idx, _Head, false>
202 constexpr _Head_base()
205 constexpr _Head_base(const _Head& __h)
206 : _M_head_impl(__h) { }
208 constexpr _Head_base(const _Head_base&) = default;
209 constexpr _Head_base(_Head_base&&) = default;
211 template<typename _UHead>
212 constexpr _Head_base(_UHead&& __h)
213 : _M_head_impl(std::forward<_UHead>(__h)) { }
216 _Head_base(allocator_arg_t, __uses_alloc0)
219 template<typename _Alloc>
221 _Head_base(allocator_arg_t, __uses_alloc1<_Alloc> __a)
222 : _M_head_impl(allocator_arg, *__a._M_a) { }
224 template<typename _Alloc>
226 _Head_base(allocator_arg_t, __uses_alloc2<_Alloc> __a)
227 : _M_head_impl(*__a._M_a) { }
229 template<typename _UHead>
231 _Head_base(__uses_alloc0, _UHead&& __uhead)
232 : _M_head_impl(std::forward<_UHead>(__uhead)) { }
234 template<typename _Alloc, typename _UHead>
236 _Head_base(__uses_alloc1<_Alloc> __a, _UHead&& __uhead)
237 : _M_head_impl(allocator_arg, *__a._M_a, std::forward<_UHead>(__uhead))
240 template<typename _Alloc, typename _UHead>
242 _Head_base(__uses_alloc2<_Alloc> __a, _UHead&& __uhead)
243 : _M_head_impl(std::forward<_UHead>(__uhead), *__a._M_a) { }
245 static constexpr _Head&
246 _M_head(_Head_base& __b) noexcept { return __b._M_head_impl; }
248 static constexpr const _Head&
249 _M_head(const _Head_base& __b) noexcept { return __b._M_head_impl; }
254#if __cpp_lib_tuple_like // >= C++23
255 struct __tuple_like_tag_t { explicit __tuple_like_tag_t() = default; };
257 // This forward declaration is used by the operator<=> overload for
259 template<typename _Cat, typename _Tp, typename _Up, typename _IndexSeq>
261 __tuple_cmp(const _Tp& __t, const _Up& __u, _IndexSeq);
265 * Contains the actual implementation of the @c tuple template, stored
266 * as a recursive inheritance hierarchy from the first element (most
267 * derived class) to the last (least derived class). The @c Idx
268 * parameter gives the 0-based index of the element stored at this
269 * point in the hierarchy; we use it to implement a constant-time
272 template<size_t _Idx, typename... _Elements>
276 * Recursive tuple implementation. Here we store the @c Head element
277 * and derive from a @c Tuple_impl containing the remaining elements
278 * (which contains the @c Tail).
280 template<size_t _Idx, typename _Head, typename... _Tail>
281 struct _Tuple_impl<_Idx, _Head, _Tail...>
282 : public _Tuple_impl<_Idx + 1, _Tail...>,
283 private _Head_base<_Idx, _Head>
285 template<size_t, typename...> friend struct _Tuple_impl;
287 typedef _Tuple_impl<_Idx + 1, _Tail...> _Inherited;
288 typedef _Head_base<_Idx, _Head> _Base;
290 static constexpr _Head&
291 _M_head(_Tuple_impl& __t) noexcept { return _Base::_M_head(__t); }
293 static constexpr const _Head&
294 _M_head(const _Tuple_impl& __t) noexcept { return _Base::_M_head(__t); }
296 static constexpr _Inherited&
297 _M_tail(_Tuple_impl& __t) noexcept { return __t; }
299 static constexpr const _Inherited&
300 _M_tail(const _Tuple_impl& __t) noexcept { return __t; }
302 constexpr _Tuple_impl()
303 : _Inherited(), _Base() { }
306 _Tuple_impl(const _Head& __head, const _Tail&... __tail)
307 : _Inherited(__tail...), _Base(__head)
310 template<typename _UHead, typename... _UTail,
311 typename = __enable_if_t<sizeof...(_Tail) == sizeof...(_UTail)>>
313 _Tuple_impl(_UHead&& __head, _UTail&&... __tail)
314 : _Inherited(std::forward<_UTail>(__tail)...),
315 _Base(std::forward<_UHead>(__head))
318 constexpr _Tuple_impl(const _Tuple_impl&) = default;
320 // _GLIBCXX_RESOLVE_LIB_DEFECTS
321 // 2729. Missing SFINAE on std::pair::operator=
322 _Tuple_impl& operator=(const _Tuple_impl&) = delete;
324 _Tuple_impl(_Tuple_impl&&) = default;
326 template<typename... _UElements>
328 _Tuple_impl(const _Tuple_impl<_Idx, _UElements...>& __in)
329 : _Inherited(_Tuple_impl<_Idx, _UElements...>::_M_tail(__in)),
330 _Base(_Tuple_impl<_Idx, _UElements...>::_M_head(__in))
333 template<typename _UHead, typename... _UTails>
335 _Tuple_impl(_Tuple_impl<_Idx, _UHead, _UTails...>&& __in)
336 : _Inherited(std::move
337 (_Tuple_impl<_Idx, _UHead, _UTails...>::_M_tail(__in))),
338 _Base(std::forward<_UHead>
339 (_Tuple_impl<_Idx, _UHead, _UTails...>::_M_head(__in)))
342#if __cpp_lib_ranges_zip // >= C++23
343 template<typename... _UElements>
345 _Tuple_impl(_Tuple_impl<_Idx, _UElements...>& __in)
346 : _Inherited(_Tuple_impl<_Idx, _UElements...>::_M_tail(__in)),
347 _Base(_Tuple_impl<_Idx, _UElements...>::_M_head(__in))
350 template<typename _UHead, typename... _UTails>
352 _Tuple_impl(const _Tuple_impl<_Idx, _UHead, _UTails...>&& __in)
353 : _Inherited(std::move
354 (_Tuple_impl<_Idx, _UHead, _UTails...>::_M_tail(__in))),
355 _Base(std::forward<const _UHead>
356 (_Tuple_impl<_Idx, _UHead, _UTails...>::_M_head(__in)))
360#if __cpp_lib_tuple_like // >= C++23
361 template<typename _UTuple, size_t... _Is>
363 _Tuple_impl(__tuple_like_tag_t, _UTuple&& __u, index_sequence<_Is...>)
364 : _Tuple_impl(std::get<_Is>(std::forward<_UTuple>(__u))...)
368 template<typename _Alloc>
370 _Tuple_impl(allocator_arg_t __tag, const _Alloc& __a)
371 : _Inherited(__tag, __a),
372 _Base(__tag, __use_alloc<_Head>(__a))
375 template<typename _Alloc>
377 _Tuple_impl(allocator_arg_t __tag, const _Alloc& __a,
378 const _Head& __head, const _Tail&... __tail)
379 : _Inherited(__tag, __a, __tail...),
380 _Base(__use_alloc<_Head, _Alloc, _Head>(__a), __head)
383 template<typename _Alloc, typename _UHead, typename... _UTail,
384 typename = __enable_if_t<sizeof...(_Tail) == sizeof...(_UTail)>>
386 _Tuple_impl(allocator_arg_t __tag, const _Alloc& __a,
387 _UHead&& __head, _UTail&&... __tail)
388 : _Inherited(__tag, __a, std::forward<_UTail>(__tail)...),
389 _Base(__use_alloc<_Head, _Alloc, _UHead>(__a),
390 std::forward<_UHead>(__head))
393 template<typename _Alloc>
395 _Tuple_impl(allocator_arg_t __tag, const _Alloc& __a,
396 const _Tuple_impl& __in)
397 : _Inherited(__tag, __a, _M_tail(__in)),
398 _Base(__use_alloc<_Head, _Alloc, _Head>(__a), _M_head(__in))
401 template<typename _Alloc>
403 _Tuple_impl(allocator_arg_t __tag, const _Alloc& __a,
405 : _Inherited(__tag, __a, std::move(_M_tail(__in))),
406 _Base(__use_alloc<_Head, _Alloc, _Head>(__a),
407 std::forward<_Head>(_M_head(__in)))
410 template<typename _Alloc, typename _UHead, typename... _UTails>
412 _Tuple_impl(allocator_arg_t __tag, const _Alloc& __a,
413 const _Tuple_impl<_Idx, _UHead, _UTails...>& __in)
414 : _Inherited(__tag, __a,
415 _Tuple_impl<_Idx, _UHead, _UTails...>::_M_tail(__in)),
416 _Base(__use_alloc<_Head, _Alloc, const _UHead&>(__a),
417 _Tuple_impl<_Idx, _UHead, _UTails...>::_M_head(__in))
420 template<typename _Alloc, typename _UHead, typename... _UTails>
422 _Tuple_impl(allocator_arg_t __tag, const _Alloc& __a,
423 _Tuple_impl<_Idx, _UHead, _UTails...>&& __in)
424 : _Inherited(__tag, __a, std::move
425 (_Tuple_impl<_Idx, _UHead, _UTails...>::_M_tail(__in))),
426 _Base(__use_alloc<_Head, _Alloc, _UHead>(__a),
428 (_Tuple_impl<_Idx, _UHead, _UTails...>::_M_head(__in)))
431#if __cpp_lib_ranges_zip // >= C++23
432 template<typename _Alloc, typename _UHead, typename... _UTails>
434 _Tuple_impl(allocator_arg_t __tag, const _Alloc& __a,
435 _Tuple_impl<_Idx, _UHead, _UTails...>& __in)
436 : _Inherited(__tag, __a,
437 _Tuple_impl<_Idx, _UHead, _UTails...>::_M_tail(__in)),
438 _Base(__use_alloc<_Head, _Alloc, _UHead&>(__a),
439 _Tuple_impl<_Idx, _UHead, _UTails...>::_M_head(__in))
442 template<typename _Alloc, typename _UHead, typename... _UTails>
444 _Tuple_impl(allocator_arg_t __tag, const _Alloc& __a,
445 const _Tuple_impl<_Idx, _UHead, _UTails...>&& __in)
446 : _Inherited(__tag, __a, std::move
447 (_Tuple_impl<_Idx, _UHead, _UTails...>::_M_tail(__in))),
448 _Base(__use_alloc<_Head, _Alloc, const _UHead>(__a),
449 std::forward<const _UHead>
450 (_Tuple_impl<_Idx, _UHead, _UTails...>::_M_head(__in)))
454#if __cpp_lib_tuple_like // >= C++23
455 template<typename _Alloc, typename _UTuple, size_t... _Is>
457 _Tuple_impl(__tuple_like_tag_t, allocator_arg_t __tag, const _Alloc& __a,
458 _UTuple&& __u, index_sequence<_Is...>)
459 : _Tuple_impl(__tag, __a, std::get<_Is>(std::forward<_UTuple>(__u))...)
463 template<typename... _UElements>
466 _M_assign(const _Tuple_impl<_Idx, _UElements...>& __in)
468 _M_head(*this) = _Tuple_impl<_Idx, _UElements...>::_M_head(__in);
469 _M_tail(*this)._M_assign(
470 _Tuple_impl<_Idx, _UElements...>::_M_tail(__in));
473 template<typename _UHead, typename... _UTails>
476 _M_assign(_Tuple_impl<_Idx, _UHead, _UTails...>&& __in)
478 _M_head(*this) = std::forward<_UHead>
479 (_Tuple_impl<_Idx, _UHead, _UTails...>::_M_head(__in));
480 _M_tail(*this)._M_assign(
481 std::move(_Tuple_impl<_Idx, _UHead, _UTails...>::_M_tail(__in)));
484#if __cpp_lib_ranges_zip // >= C++23
485 template<typename... _UElements>
487 _M_assign(const _Tuple_impl<_Idx, _UElements...>& __in) const
489 _M_head(*this) = _Tuple_impl<_Idx, _UElements...>::_M_head(__in);
490 _M_tail(*this)._M_assign(
491 _Tuple_impl<_Idx, _UElements...>::_M_tail(__in));
494 template<typename _UHead, typename... _UTails>
496 _M_assign(_Tuple_impl<_Idx, _UHead, _UTails...>&& __in) const
498 _M_head(*this) = std::forward<_UHead>
499 (_Tuple_impl<_Idx, _UHead, _UTails...>::_M_head(__in));
500 _M_tail(*this)._M_assign(
501 std::move(_Tuple_impl<_Idx, _UHead, _UTails...>::_M_tail(__in)));
505#if __cpp_lib_tuple_like // >= C++23
506 template<typename _UTuple>
508 _M_assign(__tuple_like_tag_t __tag, _UTuple&& __u)
510 _M_head(*this) = std::get<_Idx>(std::forward<_UTuple>(__u));
511 _M_tail(*this)._M_assign(__tag, std::forward<_UTuple>(__u));
514 template<typename _UTuple>
516 _M_assign(__tuple_like_tag_t __tag, _UTuple&& __u) const
518 _M_head(*this) = std::get<_Idx>(std::forward<_UTuple>(__u));
519 _M_tail(*this)._M_assign(__tag, std::forward<_UTuple>(__u));
526 _M_swap(_Tuple_impl& __in)
529 swap(_M_head(*this), _M_head(__in));
530 _Inherited::_M_swap(_M_tail(__in));
533#if __cpp_lib_ranges_zip // >= C++23
535 _M_swap(const _Tuple_impl& __in) const
538 swap(_M_head(*this), _M_head(__in));
539 _Inherited::_M_swap(_M_tail(__in));
544 // Basis case of inheritance recursion.
545 template<size_t _Idx, typename _Head>
546 struct _Tuple_impl<_Idx, _Head>
547 : private _Head_base<_Idx, _Head>
549 template<size_t, typename...> friend struct _Tuple_impl;
551 typedef _Head_base<_Idx, _Head> _Base;
553 static constexpr _Head&
554 _M_head(_Tuple_impl& __t) noexcept { return _Base::_M_head(__t); }
556 static constexpr const _Head&
557 _M_head(const _Tuple_impl& __t) noexcept { return _Base::_M_head(__t); }
564 _Tuple_impl(const _Head& __head)
568 template<typename _UHead>
570 _Tuple_impl(_UHead&& __head)
571 : _Base(std::forward<_UHead>(__head))
574 constexpr _Tuple_impl(const _Tuple_impl&) = default;
576 // _GLIBCXX_RESOLVE_LIB_DEFECTS
577 // 2729. Missing SFINAE on std::pair::operator=
578 _Tuple_impl& operator=(const _Tuple_impl&) = delete;
580#if _GLIBCXX_INLINE_VERSION
581 _Tuple_impl(_Tuple_impl&&) = default;
584 _Tuple_impl(_Tuple_impl&& __in)
585 noexcept(is_nothrow_move_constructible<_Head>::value)
586 : _Base(static_cast<_Base&&>(__in))
590 template<typename _UHead>
592 _Tuple_impl(const _Tuple_impl<_Idx, _UHead>& __in)
593 : _Base(_Tuple_impl<_Idx, _UHead>::_M_head(__in))
596 template<typename _UHead>
598 _Tuple_impl(_Tuple_impl<_Idx, _UHead>&& __in)
599 : _Base(std::forward<_UHead>(_Tuple_impl<_Idx, _UHead>::_M_head(__in)))
602#if __cpp_lib_ranges_zip // >= C++23
603 template<typename _UHead>
605 _Tuple_impl(_Tuple_impl<_Idx, _UHead>& __in)
606 : _Base(_Tuple_impl<_Idx, _UHead>::_M_head(__in))
609 template<typename _UHead>
611 _Tuple_impl(const _Tuple_impl<_Idx, _UHead>&& __in)
612 : _Base(std::forward<const _UHead>(_Tuple_impl<_Idx, _UHead>::_M_head(__in)))
616#if __cpp_lib_tuple_like // >= C++23
617 template<typename _UTuple>
619 _Tuple_impl(__tuple_like_tag_t, _UTuple&& __u, index_sequence<0>)
620 : _Tuple_impl(std::get<0>(std::forward<_UTuple>(__u)))
624 template<typename _Alloc>
626 _Tuple_impl(allocator_arg_t __tag, const _Alloc& __a)
627 : _Base(__tag, __use_alloc<_Head>(__a))
630 template<typename _Alloc>
632 _Tuple_impl(allocator_arg_t, const _Alloc& __a,
634 : _Base(__use_alloc<_Head, _Alloc, const _Head&>(__a), __head)
637 template<typename _Alloc, typename _UHead>
639 _Tuple_impl(allocator_arg_t, const _Alloc& __a,
641 : _Base(__use_alloc<_Head, _Alloc, _UHead>(__a),
642 std::forward<_UHead>(__head))
645 template<typename _Alloc>
647 _Tuple_impl(allocator_arg_t, const _Alloc& __a,
648 const _Tuple_impl& __in)
649 : _Base(__use_alloc<_Head, _Alloc, const _Head&>(__a), _M_head(__in))
652 template<typename _Alloc>
654 _Tuple_impl(allocator_arg_t, const _Alloc& __a,
656 : _Base(__use_alloc<_Head, _Alloc, _Head>(__a),
657 std::forward<_Head>(_M_head(__in)))
660 template<typename _Alloc, typename _UHead>
662 _Tuple_impl(allocator_arg_t, const _Alloc& __a,
663 const _Tuple_impl<_Idx, _UHead>& __in)
664 : _Base(__use_alloc<_Head, _Alloc, const _UHead&>(__a),
665 _Tuple_impl<_Idx, _UHead>::_M_head(__in))
668 template<typename _Alloc, typename _UHead>
670 _Tuple_impl(allocator_arg_t, const _Alloc& __a,
671 _Tuple_impl<_Idx, _UHead>&& __in)
672 : _Base(__use_alloc<_Head, _Alloc, _UHead>(__a),
673 std::forward<_UHead>(_Tuple_impl<_Idx, _UHead>::_M_head(__in)))
676#if __cpp_lib_ranges_zip // >= C++23
677 template<typename _Alloc, typename _UHead>
679 _Tuple_impl(allocator_arg_t, const _Alloc& __a,
680 _Tuple_impl<_Idx, _UHead>& __in)
681 : _Base(__use_alloc<_Head, _Alloc, _UHead&>(__a),
682 _Tuple_impl<_Idx, _UHead>::_M_head(__in))
685 template<typename _Alloc, typename _UHead>
687 _Tuple_impl(allocator_arg_t, const _Alloc& __a,
688 const _Tuple_impl<_Idx, _UHead>&& __in)
689 : _Base(__use_alloc<_Head, _Alloc, const _UHead>(__a),
690 std::forward<const _UHead>(_Tuple_impl<_Idx, _UHead>::_M_head(__in)))
694#if __cpp_lib_tuple_like // >= C++23
695 template<typename _Alloc, typename _UTuple>
697 _Tuple_impl(__tuple_like_tag_t, allocator_arg_t __tag, const _Alloc& __a,
698 _UTuple&& __u, index_sequence<0>)
699 : _Tuple_impl(__tag, __a, std::get<0>(std::forward<_UTuple>(__u)))
703 template<typename _UHead>
706 _M_assign(const _Tuple_impl<_Idx, _UHead>& __in)
708 _M_head(*this) = _Tuple_impl<_Idx, _UHead>::_M_head(__in);
711 template<typename _UHead>
714 _M_assign(_Tuple_impl<_Idx, _UHead>&& __in)
717 = std::forward<_UHead>(_Tuple_impl<_Idx, _UHead>::_M_head(__in));
720#if __cpp_lib_ranges_zip // >= C++23
721 template<typename _UHead>
723 _M_assign(const _Tuple_impl<_Idx, _UHead>& __in) const
725 _M_head(*this) = _Tuple_impl<_Idx, _UHead>::_M_head(__in);
728 template<typename _UHead>
730 _M_assign(_Tuple_impl<_Idx, _UHead>&& __in) const
733 = std::forward<_UHead>(_Tuple_impl<_Idx, _UHead>::_M_head(__in));
737#if __cpp_lib_tuple_like // >= C++23
738 template<typename _UTuple>
740 _M_assign(__tuple_like_tag_t, _UTuple&& __u)
741 { _M_head(*this) = std::get<_Idx>(std::forward<_UTuple>(__u)); }
743 template<typename _UTuple>
745 _M_assign(__tuple_like_tag_t, _UTuple&& __u) const
746 { _M_head(*this) = std::get<_Idx>(std::forward<_UTuple>(__u)); }
752 _M_swap(_Tuple_impl& __in)
755 swap(_M_head(*this), _M_head(__in));
758#if __cpp_lib_ranges_zip // >= C++23
760 _M_swap(const _Tuple_impl& __in) const
763 swap(_M_head(*this), _M_head(__in));
768 // Concept utility functions, reused in conditionally-explicit
770 template<bool, typename... _Types>
771 struct _TupleConstraints
773 template<typename... _UTypes>
774 using __constructible = __and_<is_constructible<_Types, _UTypes>...>;
776 template<typename... _UTypes>
777 using __convertible = __and_<is_convertible<_UTypes, _Types>...>;
779 // Constraint for a non-explicit constructor.
780 // True iff each Ti in _Types... can be constructed from Ui in _UTypes...
781 // and every Ui is implicitly convertible to Ti.
782 template<typename... _UTypes>
783 static constexpr bool __is_implicitly_constructible()
785 return __and_<__constructible<_UTypes...>,
786 __convertible<_UTypes...>
790 // Constraint for a non-explicit constructor.
791 // True iff each Ti in _Types... can be constructed from Ui in _UTypes...
792 // but not every Ui is implicitly convertible to Ti.
793 template<typename... _UTypes>
794 static constexpr bool __is_explicitly_constructible()
796 return __and_<__constructible<_UTypes...>,
797 __not_<__convertible<_UTypes...>>
801 static constexpr bool __is_implicitly_default_constructible()
803 return __and_<std::__is_implicitly_default_constructible<_Types>...
807 static constexpr bool __is_explicitly_default_constructible()
809 return __and_<is_default_constructible<_Types>...,
811 std::__is_implicitly_default_constructible<_Types>...>
816 // Partial specialization used when a required precondition isn't met,
817 // e.g. when sizeof...(_Types) != sizeof...(_UTypes).
818 template<typename... _Types>
819 struct _TupleConstraints<false, _Types...>
821 template<typename... _UTypes>
822 static constexpr bool __is_implicitly_constructible()
825 template<typename... _UTypes>
826 static constexpr bool __is_explicitly_constructible()
831 /// Primary class template, tuple
832 template<typename... _Elements>
833 class tuple : public _Tuple_impl<0, _Elements...>
835 using _Inherited = _Tuple_impl<0, _Elements...>;
837#if __cpp_concepts && __cpp_consteval && __cpp_conditional_explicit // >= C++20
838 template<typename... _UTypes>
839 static consteval bool
842 if constexpr (sizeof...(_UTypes) == sizeof...(_Elements))
843 return __and_v<is_constructible<_Elements, _UTypes>...>;
848 template<typename... _UTypes>
849 static consteval bool
850 __nothrow_constructible()
852 if constexpr (sizeof...(_UTypes) == sizeof...(_Elements))
853 return __and_v<is_nothrow_constructible<_Elements, _UTypes>...>;
858 template<typename... _UTypes>
859 static consteval bool
862 if constexpr (sizeof...(_UTypes) == sizeof...(_Elements))
863 return __and_v<is_convertible<_UTypes, _Elements>...>;
868 // _GLIBCXX_RESOLVE_LIB_DEFECTS
869 // 3121. tuple constructor constraints for UTypes&&... overloads
870 template<typename... _UTypes>
871 static consteval bool
872 __disambiguating_constraint()
874 if constexpr (sizeof...(_Elements) != sizeof...(_UTypes))
876 else if constexpr (sizeof...(_Elements) == 1)
878 using _U0 = typename _Nth_type<0, _UTypes...>::type;
879 return !is_same_v<remove_cvref_t<_U0>, tuple>;
881 else if constexpr (sizeof...(_Elements) < 4)
883 using _U0 = typename _Nth_type<0, _UTypes...>::type;
884 if constexpr (!is_same_v<remove_cvref_t<_U0>, allocator_arg_t>)
888 using _T0 = typename _Nth_type<0, _Elements...>::type;
889 return is_same_v<remove_cvref_t<_T0>, allocator_arg_t>;
895 // Return true iff sizeof...(Types) == 1 && tuple_size_v<TUPLE> == 1
896 // and the single element in Types can be initialized from TUPLE,
897 // or is the same type as tuple_element_t<0, TUPLE>.
898 template<typename _Tuple>
899 static consteval bool
902 if constexpr (sizeof...(_Elements) != 1)
904 else if constexpr (is_same_v<remove_cvref_t<_Tuple>, tuple>)
905 return true; // Should use a copy/move constructor instead.
908 using _Tp = typename _Nth_type<0, _Elements...>::type;
909 if constexpr (is_convertible_v<_Tuple, _Tp>)
911 else if constexpr (is_constructible_v<_Tp, _Tuple>)
917 template<typename... _Up>
918 static consteval bool
921#if __has_builtin(__reference_constructs_from_temporary)
922 return (__reference_constructs_from_temporary(_Elements, _Up&&)
929#if __cpp_lib_tuple_like // >= C++23
930 // _GLIBCXX_RESOLVE_LIB_DEFECTS
931 // 4045. tuple can create dangling references from tuple-like
932 template<typename _UTuple>
933 static consteval bool
934 __dangles_from_tuple_like()
936 return []<size_t... _Is>(index_sequence<_Is...>) {
937 return __dangles<decltype(std::get<_Is>(std::declval<_UTuple>()))...>();
938 }(index_sequence_for<_Elements...>{});
941 template<typename _UTuple>
942 static consteval bool
943 __constructible_from_tuple_like()
945 return []<size_t... _Is>(index_sequence<_Is...>) {
946 return __constructible<decltype(std::get<_Is>(std::declval<_UTuple>()))...>();
947 }(index_sequence_for<_Elements...>{});
950 template<typename _UTuple>
951 static consteval bool
952 __convertible_from_tuple_like()
954 return []<size_t... _Is>(index_sequence<_Is...>) {
955 return __convertible<decltype(std::get<_Is>(std::declval<_UTuple>()))...>();
956 }(index_sequence_for<_Elements...>{});
962 explicit(!(__is_implicitly_default_constructible_v<_Elements> && ...))
964 noexcept((is_nothrow_default_constructible_v<_Elements> && ...))
965 requires (is_default_constructible_v<_Elements> && ...)
969 constexpr explicit(!__convertible<const _Elements&...>())
970 tuple(const _Elements&... __elements)
971 noexcept(__nothrow_constructible<const _Elements&...>())
972 requires (__constructible<const _Elements&...>())
973 : _Inherited(__elements...)
976 template<typename... _UTypes>
977 requires (__disambiguating_constraint<_UTypes...>())
978 && (__constructible<_UTypes...>())
979 && (!__dangles<_UTypes...>())
980 constexpr explicit(!__convertible<_UTypes...>())
981 tuple(_UTypes&&... __u)
982 noexcept(__nothrow_constructible<_UTypes...>())
983 : _Inherited(std::forward<_UTypes>(__u)...)
986 template<typename... _UTypes>
987 requires (__disambiguating_constraint<_UTypes...>())
988 && (__constructible<_UTypes...>())
989 && (__dangles<_UTypes...>())
990 tuple(_UTypes&&...) = delete;
992 constexpr tuple(const tuple&) = default;
994 constexpr tuple(tuple&&) = default;
996 template<typename... _UTypes>
997 requires (__constructible<const _UTypes&...>())
998 && (!__use_other_ctor<const tuple<_UTypes...>&>())
999 && (!__dangles<const _UTypes&...>())
1000 constexpr explicit(!__convertible<const _UTypes&...>())
1001 tuple(const tuple<_UTypes...>& __u)
1002 noexcept(__nothrow_constructible<const _UTypes&...>())
1003 : _Inherited(static_cast<const _Tuple_impl<0, _UTypes...>&>(__u))
1006 template<typename... _UTypes>
1007 requires (__constructible<const _UTypes&...>())
1008 && (!__use_other_ctor<const tuple<_UTypes...>&>())
1009 && (__dangles<const _UTypes&...>())
1010 tuple(const tuple<_UTypes...>&) = delete;
1012 template<typename... _UTypes>
1013 requires (__constructible<_UTypes...>())
1014 && (!__use_other_ctor<tuple<_UTypes...>>())
1015 && (!__dangles<_UTypes...>())
1016 constexpr explicit(!__convertible<_UTypes...>())
1017 tuple(tuple<_UTypes...>&& __u)
1018 noexcept(__nothrow_constructible<_UTypes...>())
1019 : _Inherited(static_cast<_Tuple_impl<0, _UTypes...>&&>(__u))
1022 template<typename... _UTypes>
1023 requires (__constructible<_UTypes...>())
1024 && (!__use_other_ctor<tuple<_UTypes...>>())
1025 && (__dangles<_UTypes...>())
1026 tuple(tuple<_UTypes...>&&) = delete;
1028#if __cpp_lib_ranges_zip // >= C++23
1029 template<typename... _UTypes>
1030 requires (__constructible<_UTypes&...>())
1031 && (!__use_other_ctor<tuple<_UTypes...>&>())
1032 && (!__dangles<_UTypes&...>())
1033 constexpr explicit(!__convertible<_UTypes&...>())
1034 tuple(tuple<_UTypes...>& __u)
1035 noexcept(__nothrow_constructible<_UTypes&...>())
1036 : _Inherited(static_cast<_Tuple_impl<0, _UTypes...>&>(__u))
1039 template<typename... _UTypes>
1040 requires (__constructible<_UTypes&...>())
1041 && (!__use_other_ctor<tuple<_UTypes...>&>())
1042 && (__dangles<_UTypes&...>())
1043 tuple(tuple<_UTypes...>&) = delete;
1045 template<typename... _UTypes>
1046 requires (__constructible<const _UTypes...>())
1047 && (!__use_other_ctor<const tuple<_UTypes...>>())
1048 && (!__dangles<const _UTypes...>())
1049 constexpr explicit(!__convertible<const _UTypes...>())
1050 tuple(const tuple<_UTypes...>&& __u)
1051 noexcept(__nothrow_constructible<const _UTypes...>())
1052 : _Inherited(static_cast<const _Tuple_impl<0, _UTypes...>&&>(__u))
1055 template<typename... _UTypes>
1056 requires (__constructible<const _UTypes...>())
1057 && (!__use_other_ctor<const tuple<_UTypes...>>())
1058 && (__dangles<const _UTypes...>())
1059 tuple(const tuple<_UTypes...>&&) = delete;
1062 template<typename _U1, typename _U2>
1063 requires (sizeof...(_Elements) == 2)
1064 && (__constructible<const _U1&, const _U2&>())
1065 && (!__dangles<const _U1&, const _U2&>())
1066 constexpr explicit(!__convertible<const _U1&, const _U2&>())
1067 tuple(const pair<_U1, _U2>& __u)
1068 noexcept(__nothrow_constructible<const _U1&, const _U2&>())
1069 : _Inherited(__u.first, __u.second)
1072 template<typename _U1, typename _U2>
1073 requires (sizeof...(_Elements) == 2)
1074 && (__constructible<const _U1&, const _U2&>())
1075 && (__dangles<const _U1&, const _U2&>())
1076 tuple(const pair<_U1, _U2>&) = delete;
1078 template<typename _U1, typename _U2>
1079 requires (sizeof...(_Elements) == 2)
1080 && (__constructible<_U1, _U2>())
1081 && (!__dangles<_U1, _U2>())
1082 constexpr explicit(!__convertible<_U1, _U2>())
1083 tuple(pair<_U1, _U2>&& __u)
1084 noexcept(__nothrow_constructible<_U1, _U2>())
1085 : _Inherited(std::forward<_U1>(__u.first),
1086 std::forward<_U2>(__u.second))
1089 template<typename _U1, typename _U2>
1090 requires (sizeof...(_Elements) == 2)
1091 && (__constructible<_U1, _U2>())
1092 && (__dangles<_U1, _U2>())
1093 tuple(pair<_U1, _U2>&&) = delete;
1095#if __cpp_lib_ranges_zip // >= C++23
1096 template<typename _U1, typename _U2>
1097 requires (sizeof...(_Elements) == 2)
1098 && (__constructible<_U1&, _U2&>())
1099 && (!__dangles<_U1&, _U2&>())
1100 constexpr explicit(!__convertible<_U1&, _U2&>())
1101 tuple(pair<_U1, _U2>& __u)
1102 noexcept(__nothrow_constructible<_U1&, _U2&>())
1103 : _Inherited(__u.first, __u.second)
1106 template<typename _U1, typename _U2>
1107 requires (sizeof...(_Elements) == 2)
1108 && (__constructible<_U1&, _U2&>())
1109 && (__dangles<_U1&, _U2&>())
1110 tuple(pair<_U1, _U2>&) = delete;
1112 template<typename _U1, typename _U2>
1113 requires (sizeof...(_Elements) == 2)
1114 && (__constructible<const _U1, const _U2>())
1115 && (!__dangles<const _U1, const _U2>())
1116 constexpr explicit(!__convertible<const _U1, const _U2>())
1117 tuple(const pair<_U1, _U2>&& __u)
1118 noexcept(__nothrow_constructible<const _U1, const _U2>())
1119 : _Inherited(std::forward<const _U1>(__u.first),
1120 std::forward<const _U2>(__u.second))
1123 template<typename _U1, typename _U2>
1124 requires (sizeof...(_Elements) == 2)
1125 && (__constructible<const _U1, const _U2>())
1126 && (__dangles<const _U1, const _U2>())
1127 tuple(const pair<_U1, _U2>&&) = delete;
1130#if __cpp_lib_tuple_like // >= C++23
1131 template<__eligible_tuple_like<tuple> _UTuple>
1132 requires (__constructible_from_tuple_like<_UTuple>())
1133 && (!__use_other_ctor<_UTuple>())
1134 && (!__dangles_from_tuple_like<_UTuple>())
1135 constexpr explicit(!__convertible_from_tuple_like<_UTuple>())
1136 tuple(_UTuple&& __u)
1137 : _Inherited(__tuple_like_tag_t{},
1138 std::forward<_UTuple>(__u),
1139 index_sequence_for<_Elements...>{})
1142 template<__eligible_tuple_like<tuple> _UTuple>
1143 requires (__constructible_from_tuple_like<_UTuple>())
1144 && (!__use_other_ctor<_UTuple>())
1145 && (__dangles_from_tuple_like<_UTuple>())
1146 tuple(_UTuple&&) = delete;
1149 // Allocator-extended constructors.
1151 template<typename _Alloc>
1153 explicit(!(__is_implicitly_default_constructible_v<_Elements> && ...))
1154 tuple(allocator_arg_t __tag, const _Alloc& __a)
1155 requires (is_default_constructible_v<_Elements> && ...)
1156 : _Inherited(__tag, __a)
1159 template<typename _Alloc>
1160 constexpr explicit(!__convertible<const _Elements&...>())
1161 tuple(allocator_arg_t __tag, const _Alloc& __a,
1162 const _Elements&... __elements)
1163 requires (__constructible<const _Elements&...>())
1164 : _Inherited(__tag, __a, __elements...)
1167 template<typename _Alloc, typename... _UTypes>
1168 requires (__disambiguating_constraint<_UTypes...>())
1169 && (__constructible<_UTypes...>())
1170 && (!__dangles<_UTypes...>())
1171 constexpr explicit(!__convertible<_UTypes...>())
1172 tuple(allocator_arg_t __tag, const _Alloc& __a, _UTypes&&... __u)
1173 : _Inherited(__tag, __a, std::forward<_UTypes>(__u)...)
1176 template<typename _Alloc, typename... _UTypes>
1177 requires (__disambiguating_constraint<_UTypes...>())
1178 && (__constructible<_UTypes...>())
1179 && (__dangles<_UTypes...>())
1180 tuple(allocator_arg_t, const _Alloc&, _UTypes&&...) = delete;
1182 template<typename _Alloc>
1184 tuple(allocator_arg_t __tag, const _Alloc& __a, const tuple& __u)
1185 : _Inherited(__tag, __a, static_cast<const _Inherited&>(__u))
1188 template<typename _Alloc>
1189 requires (__constructible<_Elements...>())
1191 tuple(allocator_arg_t __tag, const _Alloc& __a, tuple&& __u)
1192 : _Inherited(__tag, __a, static_cast<_Inherited&&>(__u))
1195 template<typename _Alloc, typename... _UTypes>
1196 requires (__constructible<const _UTypes&...>())
1197 && (!__use_other_ctor<const tuple<_UTypes...>&>())
1198 && (!__dangles<const _UTypes&...>())
1199 constexpr explicit(!__convertible<const _UTypes&...>())
1200 tuple(allocator_arg_t __tag, const _Alloc& __a,
1201 const tuple<_UTypes...>& __u)
1202 : _Inherited(__tag, __a,
1203 static_cast<const _Tuple_impl<0, _UTypes...>&>(__u))
1206 template<typename _Alloc, typename... _UTypes>
1207 requires (__constructible<const _UTypes&...>())
1208 && (!__use_other_ctor<const tuple<_UTypes...>&>())
1209 && (__dangles<const _UTypes&...>())
1210 tuple(allocator_arg_t, const _Alloc&, const tuple<_UTypes...>&) = delete;
1212 template<typename _Alloc, typename... _UTypes>
1213 requires (__constructible<_UTypes...>())
1214 && (!__use_other_ctor<tuple<_UTypes...>>())
1215 && (!__dangles<_UTypes...>())
1216 constexpr explicit(!__use_other_ctor<tuple<_UTypes...>>())
1217 tuple(allocator_arg_t __tag, const _Alloc& __a, tuple<_UTypes...>&& __u)
1218 : _Inherited(__tag, __a, static_cast<_Tuple_impl<0, _UTypes...>&&>(__u))
1221 template<typename _Alloc, typename... _UTypes>
1222 requires (__constructible<_UTypes...>())
1223 && (!__use_other_ctor<tuple<_UTypes...>>())
1224 && (__dangles<_UTypes...>())
1225 tuple(allocator_arg_t, const _Alloc&, tuple<_UTypes...>&&) = delete;
1227#if __cpp_lib_ranges_zip // >= C++23
1228 template<typename _Alloc, typename... _UTypes>
1229 requires (__constructible<_UTypes&...>())
1230 && (!__use_other_ctor<tuple<_UTypes...>&>())
1231 && (!__dangles<_UTypes&...>())
1232 constexpr explicit(!__convertible<_UTypes&...>())
1233 tuple(allocator_arg_t __tag, const _Alloc& __a, tuple<_UTypes...>& __u)
1234 : _Inherited(__tag, __a, static_cast<_Tuple_impl<0, _UTypes...>&>(__u))
1237 template<typename _Alloc, typename... _UTypes>
1238 requires (__constructible<_UTypes&...>())
1239 && (!__use_other_ctor<tuple<_UTypes...>&>())
1240 && (__dangles<_UTypes&...>())
1241 tuple(allocator_arg_t, const _Alloc&, tuple<_UTypes...>&) = delete;
1243 template<typename _Alloc, typename... _UTypes>
1244 requires (__constructible<const _UTypes...>())
1245 && (!__use_other_ctor<const tuple<_UTypes...>>())
1246 && (!__dangles<const _UTypes...>())
1247 constexpr explicit(!__convertible<const _UTypes...>())
1248 tuple(allocator_arg_t __tag, const _Alloc& __a,
1249 const tuple<_UTypes...>&& __u)
1250 : _Inherited(__tag, __a,
1251 static_cast<const _Tuple_impl<0, _UTypes...>&&>(__u))
1254 template<typename _Alloc, typename... _UTypes>
1255 requires (__constructible<const _UTypes...>())
1256 && (!__use_other_ctor<const tuple<_UTypes...>>())
1257 && (__dangles<const _UTypes...>())
1258 tuple(allocator_arg_t, const _Alloc&, const tuple<_UTypes...>&&) = delete;
1261 template<typename _Alloc, typename _U1, typename _U2>
1262 requires (sizeof...(_Elements) == 2)
1263 && (__constructible<const _U1&, const _U2&>())
1264 && (!__dangles<const _U1&, const _U2&>())
1265 constexpr explicit(!__convertible<const _U1&, const _U2&>())
1266 tuple(allocator_arg_t __tag, const _Alloc& __a,
1267 const pair<_U1, _U2>& __u)
1268 noexcept(__nothrow_constructible<const _U1&, const _U2&>())
1269 : _Inherited(__tag, __a, __u.first, __u.second)
1272 template<typename _Alloc, typename _U1, typename _U2>
1273 requires (sizeof...(_Elements) == 2)
1274 && (__constructible<const _U1&, const _U2&>())
1275 && (__dangles<const _U1&, const _U2&>())
1276 tuple(allocator_arg_t, const _Alloc&, const pair<_U1, _U2>&) = delete;
1278 template<typename _Alloc, typename _U1, typename _U2>
1279 requires (sizeof...(_Elements) == 2)
1280 && (__constructible<_U1, _U2>())
1281 && (!__dangles<_U1, _U2>())
1282 constexpr explicit(!__convertible<_U1, _U2>())
1283 tuple(allocator_arg_t __tag, const _Alloc& __a, pair<_U1, _U2>&& __u)
1284 noexcept(__nothrow_constructible<_U1, _U2>())
1285 : _Inherited(__tag, __a, std::move(__u.first), std::move(__u.second))
1288 template<typename _Alloc, typename _U1, typename _U2>
1289 requires (sizeof...(_Elements) == 2)
1290 && (__constructible<_U1, _U2>())
1291 && (__dangles<_U1, _U2>())
1292 tuple(allocator_arg_t, const _Alloc&, pair<_U1, _U2>&&) = delete;
1294#if __cpp_lib_ranges_zip // >= C++23
1295 template<typename _Alloc, typename _U1, typename _U2>
1296 requires (sizeof...(_Elements) == 2)
1297 && (__constructible<_U1&, _U2&>())
1298 && (!__dangles<_U1&, _U2&>())
1299 constexpr explicit(!__convertible<_U1&, _U2&>())
1300 tuple(allocator_arg_t __tag, const _Alloc& __a, pair<_U1, _U2>& __u)
1301 noexcept(__nothrow_constructible<_U1&, _U2&>())
1302 : _Inherited(__tag, __a, __u.first, __u.second)
1305 template<typename _Alloc, typename _U1, typename _U2>
1306 requires (sizeof...(_Elements) == 2)
1307 && (__constructible<_U1&, _U2&>())
1308 && (__dangles<_U1&, _U2&>())
1309 tuple(allocator_arg_t, const _Alloc&, pair<_U1, _U2>&) = delete;
1311 template<typename _Alloc, typename _U1, typename _U2>
1312 requires (sizeof...(_Elements) == 2)
1313 && (__constructible<const _U1, const _U2>())
1314 && (!__dangles<const _U1, const _U2>())
1315 constexpr explicit(!__convertible<const _U1, const _U2>())
1316 tuple(allocator_arg_t __tag, const _Alloc& __a,
1317 const pair<_U1, _U2>&& __u)
1318 noexcept(__nothrow_constructible<const _U1, const _U2>())
1319 : _Inherited(__tag, __a, std::move(__u.first), std::move(__u.second))
1322 template<typename _Alloc, typename _U1, typename _U2>
1323 requires (sizeof...(_Elements) == 2)
1324 && (__constructible<const _U1, const _U2>())
1325 && (__dangles<const _U1, const _U2>())
1326 tuple(allocator_arg_t, const _Alloc&, const pair<_U1, _U2>&&) = delete;
1329#if __cpp_lib_tuple_like // >= C++23
1330 template<typename _Alloc, __eligible_tuple_like<tuple> _UTuple>
1331 requires (__constructible_from_tuple_like<_UTuple>())
1332 && (!__use_other_ctor<_UTuple>())
1333 && (!__dangles_from_tuple_like<_UTuple>())
1334 constexpr explicit(!__convertible_from_tuple_like<_UTuple>())
1335 tuple(allocator_arg_t __tag, const _Alloc& __a, _UTuple&& __u)
1336 : _Inherited(__tuple_like_tag_t{},
1337 __tag, __a, std::forward<_UTuple>(__u),
1338 index_sequence_for<_Elements...>{})
1341 template<typename _Alloc, __eligible_tuple_like<tuple> _UTuple>
1342 requires (__constructible_from_tuple_like<_UTuple>())
1343 && (!__use_other_ctor<_UTuple>())
1344 && (__dangles_from_tuple_like<_UTuple>())
1345 tuple(allocator_arg_t, const _Alloc&, _UTuple&&) = delete;
1348#else // !(concepts && conditional_explicit)
1350 template<bool _Cond>
1351 using _TCC = _TupleConstraints<_Cond, _Elements...>;
1353 // Constraint for non-explicit default constructor
1354 template<bool _Dummy>
1355 using _ImplicitDefaultCtor = __enable_if_t<
1356 _TCC<_Dummy>::__is_implicitly_default_constructible(),
1359 // Constraint for explicit default constructor
1360 template<bool _Dummy>
1361 using _ExplicitDefaultCtor = __enable_if_t<
1362 _TCC<_Dummy>::__is_explicitly_default_constructible(),
1365 // Constraint for non-explicit constructors
1366 template<bool _Cond, typename... _Args>
1367 using _ImplicitCtor = __enable_if_t<
1368 _TCC<_Cond>::template __is_implicitly_constructible<_Args...>(),
1371 // Constraint for non-explicit constructors
1372 template<bool _Cond, typename... _Args>
1373 using _ExplicitCtor = __enable_if_t<
1374 _TCC<_Cond>::template __is_explicitly_constructible<_Args...>(),
1377 // Condition for noexcept-specifier of a constructor.
1378 template<typename... _UElements>
1379 static constexpr bool __nothrow_constructible()
1382 __and_<is_nothrow_constructible<_Elements, _UElements>...>::value;
1385 // Constraint for tuple(_UTypes&&...) where sizeof...(_UTypes) == 1.
1386 template<typename _Up>
1387 static constexpr bool __valid_args()
1389 return sizeof...(_Elements) == 1
1390 && !is_same<tuple, __remove_cvref_t<_Up>>::value;
1393 // Constraint for tuple(_UTypes&&...) where sizeof...(_UTypes) > 1.
1394 template<typename, typename, typename... _Tail>
1395 static constexpr bool __valid_args()
1396 { return (sizeof...(_Tail) + 2) == sizeof...(_Elements); }
1398 /* Constraint for constructors with a tuple<UTypes...> parameter ensures
1399 * that the constructor is only viable when it would not interfere with
1400 * tuple(UTypes&&...) or tuple(const tuple&) or tuple(tuple&&).
1401 * Such constructors are only viable if:
1402 * either sizeof...(Types) != 1,
1403 * or (when Types... expands to T and UTypes... expands to U)
1404 * is_convertible_v<TUPLE, T>, is_constructible_v<T, TUPLE>,
1405 * and is_same_v<T, U> are all false.
1407 template<typename _Tuple, typename = tuple,
1408 typename = __remove_cvref_t<_Tuple>>
1409 struct _UseOtherCtor
1412 // If TUPLE is convertible to the single element in *this,
1413 // then TUPLE should match tuple(UTypes&&...) instead.
1414 template<typename _Tuple, typename _Tp, typename _Up>
1415 struct _UseOtherCtor<_Tuple, tuple<_Tp>, tuple<_Up>>
1416 : __or_<is_convertible<_Tuple, _Tp>, is_constructible<_Tp, _Tuple>>::type
1418 // If TUPLE and *this each have a single element of the same type,
1419 // then TUPLE should match a copy/move constructor instead.
1420 template<typename _Tuple, typename _Tp>
1421 struct _UseOtherCtor<_Tuple, tuple<_Tp>, tuple<_Tp>>
1425 // Return true iff sizeof...(Types) == 1 && tuple_size_v<TUPLE> == 1
1426 // and the single element in Types can be initialized from TUPLE,
1427 // or is the same type as tuple_element_t<0, TUPLE>.
1428 template<typename _Tuple>
1429 static constexpr bool __use_other_ctor()
1430 { return _UseOtherCtor<_Tuple>::value; }
1432 /// @cond undocumented
1433#undef __glibcxx_no_dangling_refs
1434#if __has_builtin(__reference_constructs_from_temporary) \
1435 && defined _GLIBCXX_DEBUG
1436 // Error if construction from U... would create a dangling ref.
1437# if __cpp_fold_expressions
1438# define __glibcxx_dangling_refs(U) \
1439 (__reference_constructs_from_temporary(_Elements, U) || ...)
1441# define __glibcxx_dangling_refs(U) \
1442 __or_<__bool_constant<__reference_constructs_from_temporary(_Elements, U) \
1445# define __glibcxx_no_dangling_refs(U) \
1446 static_assert(!__glibcxx_dangling_refs(U), \
1447 "std::tuple constructor creates a dangling reference")
1449# define __glibcxx_no_dangling_refs(U)
1454 template<typename _Dummy = void,
1455 _ImplicitDefaultCtor<is_void<_Dummy>::value> = true>
1458 noexcept(__and_<is_nothrow_default_constructible<_Elements>...>::value)
1461 template<typename _Dummy = void,
1462 _ExplicitDefaultCtor<is_void<_Dummy>::value> = false>
1465 noexcept(__and_<is_nothrow_default_constructible<_Elements>...>::value)
1468 template<bool _NotEmpty = (sizeof...(_Elements) >= 1),
1469 _ImplicitCtor<_NotEmpty, const _Elements&...> = true>
1471 tuple(const _Elements&... __elements)
1472 noexcept(__nothrow_constructible<const _Elements&...>())
1473 : _Inherited(__elements...) { }
1475 template<bool _NotEmpty = (sizeof...(_Elements) >= 1),
1476 _ExplicitCtor<_NotEmpty, const _Elements&...> = false>
1478 tuple(const _Elements&... __elements)
1479 noexcept(__nothrow_constructible<const _Elements&...>())
1480 : _Inherited(__elements...) { }
1482 template<typename... _UElements,
1483 bool _Valid = __valid_args<_UElements...>(),
1484 _ImplicitCtor<_Valid, _UElements...> = true>
1486 tuple(_UElements&&... __elements)
1487 noexcept(__nothrow_constructible<_UElements...>())
1488 : _Inherited(std::forward<_UElements>(__elements)...)
1489 { __glibcxx_no_dangling_refs(_UElements&&); }
1491 template<typename... _UElements,
1492 bool _Valid = __valid_args<_UElements...>(),
1493 _ExplicitCtor<_Valid, _UElements...> = false>
1495 tuple(_UElements&&... __elements)
1496 noexcept(__nothrow_constructible<_UElements...>())
1497 : _Inherited(std::forward<_UElements>(__elements)...)
1498 { __glibcxx_no_dangling_refs(_UElements&&); }
1500 constexpr tuple(const tuple&) = default;
1502 constexpr tuple(tuple&&) = default;
1504 template<typename... _UElements,
1505 bool _Valid = (sizeof...(_Elements) == sizeof...(_UElements))
1506 && !__use_other_ctor<const tuple<_UElements...>&>(),
1507 _ImplicitCtor<_Valid, const _UElements&...> = true>
1509 tuple(const tuple<_UElements...>& __in)
1510 noexcept(__nothrow_constructible<const _UElements&...>())
1511 : _Inherited(static_cast<const _Tuple_impl<0, _UElements...>&>(__in))
1512 { __glibcxx_no_dangling_refs(const _UElements&); }
1514 template<typename... _UElements,
1515 bool _Valid = (sizeof...(_Elements) == sizeof...(_UElements))
1516 && !__use_other_ctor<const tuple<_UElements...>&>(),
1517 _ExplicitCtor<_Valid, const _UElements&...> = false>
1519 tuple(const tuple<_UElements...>& __in)
1520 noexcept(__nothrow_constructible<const _UElements&...>())
1521 : _Inherited(static_cast<const _Tuple_impl<0, _UElements...>&>(__in))
1522 { __glibcxx_no_dangling_refs(const _UElements&); }
1524 template<typename... _UElements,
1525 bool _Valid = (sizeof...(_Elements) == sizeof...(_UElements))
1526 && !__use_other_ctor<tuple<_UElements...>&&>(),
1527 _ImplicitCtor<_Valid, _UElements...> = true>
1529 tuple(tuple<_UElements...>&& __in)
1530 noexcept(__nothrow_constructible<_UElements...>())
1531 : _Inherited(static_cast<_Tuple_impl<0, _UElements...>&&>(__in))
1532 { __glibcxx_no_dangling_refs(_UElements&&); }
1534 template<typename... _UElements,
1535 bool _Valid = (sizeof...(_Elements) == sizeof...(_UElements))
1536 && !__use_other_ctor<tuple<_UElements...>&&>(),
1537 _ExplicitCtor<_Valid, _UElements...> = false>
1539 tuple(tuple<_UElements...>&& __in)
1540 noexcept(__nothrow_constructible<_UElements...>())
1541 : _Inherited(static_cast<_Tuple_impl<0, _UElements...>&&>(__in))
1542 { __glibcxx_no_dangling_refs(_UElements&&); }
1544 // Allocator-extended constructors.
1546 template<typename _Alloc,
1547 _ImplicitDefaultCtor<is_object<_Alloc>::value> = true>
1548 _GLIBCXX20_CONSTEXPR
1549 tuple(allocator_arg_t __tag, const _Alloc& __a)
1550 : _Inherited(__tag, __a) { }
1552 template<typename _Alloc,
1553 _ExplicitDefaultCtor<is_object<_Alloc>::value> = false>
1554 _GLIBCXX20_CONSTEXPR
1556 tuple(allocator_arg_t __tag, const _Alloc& __a)
1557 : _Inherited(__tag, __a) { }
1559 template<typename _Alloc, bool _NotEmpty = (sizeof...(_Elements) >= 1),
1560 _ImplicitCtor<_NotEmpty, const _Elements&...> = true>
1561 _GLIBCXX20_CONSTEXPR
1562 tuple(allocator_arg_t __tag, const _Alloc& __a,
1563 const _Elements&... __elements)
1564 : _Inherited(__tag, __a, __elements...) { }
1566 template<typename _Alloc, bool _NotEmpty = (sizeof...(_Elements) >= 1),
1567 _ExplicitCtor<_NotEmpty, const _Elements&...> = false>
1568 _GLIBCXX20_CONSTEXPR
1570 tuple(allocator_arg_t __tag, const _Alloc& __a,
1571 const _Elements&... __elements)
1572 : _Inherited(__tag, __a, __elements...) { }
1574 template<typename _Alloc, typename... _UElements,
1575 bool _Valid = __valid_args<_UElements...>(),
1576 _ImplicitCtor<_Valid, _UElements...> = true>
1577 _GLIBCXX20_CONSTEXPR
1578 tuple(allocator_arg_t __tag, const _Alloc& __a,
1579 _UElements&&... __elements)
1580 : _Inherited(__tag, __a, std::forward<_UElements>(__elements)...)
1581 { __glibcxx_no_dangling_refs(_UElements&&); }
1583 template<typename _Alloc, typename... _UElements,
1584 bool _Valid = __valid_args<_UElements...>(),
1585 _ExplicitCtor<_Valid, _UElements...> = false>
1586 _GLIBCXX20_CONSTEXPR
1588 tuple(allocator_arg_t __tag, const _Alloc& __a,
1589 _UElements&&... __elements)
1590 : _Inherited(__tag, __a, std::forward<_UElements>(__elements)...)
1591 { __glibcxx_no_dangling_refs(_UElements&&); }
1593 template<typename _Alloc>
1594 _GLIBCXX20_CONSTEXPR
1595 tuple(allocator_arg_t __tag, const _Alloc& __a, const tuple& __in)
1596 : _Inherited(__tag, __a, static_cast<const _Inherited&>(__in)) { }
1598 template<typename _Alloc>
1599 _GLIBCXX20_CONSTEXPR
1600 tuple(allocator_arg_t __tag, const _Alloc& __a, tuple&& __in)
1601 : _Inherited(__tag, __a, static_cast<_Inherited&&>(__in)) { }
1603 template<typename _Alloc, typename... _UElements,
1604 bool _Valid = (sizeof...(_Elements) == sizeof...(_UElements))
1605 && !__use_other_ctor<const tuple<_UElements...>&>(),
1606 _ImplicitCtor<_Valid, const _UElements&...> = true>
1607 _GLIBCXX20_CONSTEXPR
1608 tuple(allocator_arg_t __tag, const _Alloc& __a,
1609 const tuple<_UElements...>& __in)
1610 : _Inherited(__tag, __a,
1611 static_cast<const _Tuple_impl<0, _UElements...>&>(__in))
1612 { __glibcxx_no_dangling_refs(const _UElements&); }
1614 template<typename _Alloc, typename... _UElements,
1615 bool _Valid = (sizeof...(_Elements) == sizeof...(_UElements))
1616 && !__use_other_ctor<const tuple<_UElements...>&>(),
1617 _ExplicitCtor<_Valid, const _UElements&...> = false>
1618 _GLIBCXX20_CONSTEXPR
1620 tuple(allocator_arg_t __tag, const _Alloc& __a,
1621 const tuple<_UElements...>& __in)
1622 : _Inherited(__tag, __a,
1623 static_cast<const _Tuple_impl<0, _UElements...>&>(__in))
1624 { __glibcxx_no_dangling_refs(const _UElements&); }
1626 template<typename _Alloc, typename... _UElements,
1627 bool _Valid = (sizeof...(_Elements) == sizeof...(_UElements))
1628 && !__use_other_ctor<tuple<_UElements...>&&>(),
1629 _ImplicitCtor<_Valid, _UElements...> = true>
1630 _GLIBCXX20_CONSTEXPR
1631 tuple(allocator_arg_t __tag, const _Alloc& __a,
1632 tuple<_UElements...>&& __in)
1633 : _Inherited(__tag, __a,
1634 static_cast<_Tuple_impl<0, _UElements...>&&>(__in))
1635 { __glibcxx_no_dangling_refs(_UElements&&); }
1637 template<typename _Alloc, typename... _UElements,
1638 bool _Valid = (sizeof...(_Elements) == sizeof...(_UElements))
1639 && !__use_other_ctor<tuple<_UElements...>&&>(),
1640 _ExplicitCtor<_Valid, _UElements...> = false>
1641 _GLIBCXX20_CONSTEXPR
1643 tuple(allocator_arg_t __tag, const _Alloc& __a,
1644 tuple<_UElements...>&& __in)
1645 : _Inherited(__tag, __a,
1646 static_cast<_Tuple_impl<0, _UElements...>&&>(__in))
1647 { __glibcxx_no_dangling_refs(_UElements&&); }
1648#endif // concepts && conditional_explicit
1652#if __cpp_concepts && __cpp_consteval // >= C++20
1654 template<typename... _UTypes>
1655 static consteval bool
1658 if constexpr (sizeof...(_UTypes) == sizeof...(_Elements))
1659 return __and_v<is_assignable<_Elements&, _UTypes>...>;
1664 template<typename... _UTypes>
1665 static consteval bool
1666 __nothrow_assignable()
1668 if constexpr (sizeof...(_UTypes) == sizeof...(_Elements))
1669 return __and_v<is_nothrow_assignable<_Elements&, _UTypes>...>;
1674#if __cpp_lib_ranges_zip // >= C++23
1675 template<typename... _UTypes>
1676 static consteval bool
1677 __const_assignable()
1679 if constexpr (sizeof...(_UTypes) == sizeof...(_Elements))
1680 return __and_v<is_assignable<const _Elements&, _UTypes>...>;
1686#if __cpp_lib_tuple_like // >= C++23
1687 template<typename _UTuple>
1688 static consteval bool
1689 __assignable_from_tuple_like()
1691 return []<size_t... _Is>(index_sequence<_Is...>) {
1692 return __assignable<decltype(std::get<_Is>(std::declval<_UTuple>()))...>();
1693 }(index_sequence_for<_Elements...>{});
1696 template<typename _UTuple>
1697 static consteval bool
1698 __const_assignable_from_tuple_like()
1700 return []<size_t... _Is>(index_sequence<_Is...>) {
1701 return __const_assignable<decltype(std::get<_Is>(std::declval<_UTuple>()))...>();
1702 }(index_sequence_for<_Elements...>{});
1708 tuple& operator=(const tuple& __u) = delete;
1711 operator=(const tuple& __u)
1712 noexcept(__nothrow_assignable<const _Elements&...>())
1713 requires (__assignable<const _Elements&...>())
1715 this->_M_assign(__u);
1720 operator=(tuple&& __u)
1721 noexcept(__nothrow_assignable<_Elements...>())
1722 requires (__assignable<_Elements...>())
1724 this->_M_assign(std::move(__u));
1728 template<typename... _UTypes>
1729 requires (__assignable<const _UTypes&...>())
1731 operator=(const tuple<_UTypes...>& __u)
1732 noexcept(__nothrow_assignable<const _UTypes&...>())
1734 this->_M_assign(__u);
1738 template<typename... _UTypes>
1739 requires (__assignable<_UTypes...>())
1741 operator=(tuple<_UTypes...>&& __u)
1742 noexcept(__nothrow_assignable<_UTypes...>())
1744 this->_M_assign(std::move(__u));
1748#if __cpp_lib_ranges_zip // >= C++23
1749 constexpr const tuple&
1750 operator=(const tuple& __u) const
1751 requires (__const_assignable<const _Elements&...>())
1753 this->_M_assign(__u);
1757 constexpr const tuple&
1758 operator=(tuple&& __u) const
1759 requires (__const_assignable<_Elements...>())
1761 this->_M_assign(std::move(__u));
1765 template<typename... _UTypes>
1766 constexpr const tuple&
1767 operator=(const tuple<_UTypes...>& __u) const
1768 requires (__const_assignable<const _UTypes&...>())
1770 this->_M_assign(__u);
1774 template<typename... _UTypes>
1775 constexpr const tuple&
1776 operator=(tuple<_UTypes...>&& __u) const
1777 requires (__const_assignable<_UTypes...>())
1779 this->_M_assign(std::move(__u));
1784 template<typename _U1, typename _U2>
1785 requires (__assignable<const _U1&, const _U2&>())
1787 operator=(const pair<_U1, _U2>& __u)
1788 noexcept(__nothrow_assignable<const _U1&, const _U2&>())
1790 this->_M_head(*this) = __u.first;
1791 this->_M_tail(*this)._M_head(*this) = __u.second;
1795 template<typename _U1, typename _U2>
1796 requires (__assignable<_U1, _U2>())
1798 operator=(pair<_U1, _U2>&& __u)
1799 noexcept(__nothrow_assignable<_U1, _U2>())
1801 this->_M_head(*this) = std::forward<_U1>(__u.first);
1802 this->_M_tail(*this)._M_head(*this) = std::forward<_U2>(__u.second);
1806#if __cpp_lib_ranges_zip // >= C++23
1807 template<typename _U1, typename _U2>
1808 requires (__const_assignable<const _U1&, const _U2>())
1809 constexpr const tuple&
1810 operator=(const pair<_U1, _U2>& __u) const
1812 this->_M_head(*this) = __u.first;
1813 this->_M_tail(*this)._M_head(*this) = __u.second;
1817 template<typename _U1, typename _U2>
1818 requires (__const_assignable<_U1, _U2>())
1819 constexpr const tuple&
1820 operator=(pair<_U1, _U2>&& __u) const
1822 this->_M_head(*this) = std::forward<_U1>(__u.first);
1823 this->_M_tail(*this)._M_head(*this) = std::forward<_U2>(__u.second);
1828#if __cpp_lib_tuple_like // >= C++23
1829 template<__eligible_tuple_like<tuple> _UTuple>
1830 requires (__assignable_from_tuple_like<_UTuple>())
1832 operator=(_UTuple&& __u)
1834 this->_M_assign(__tuple_like_tag_t{}, std::forward<_UTuple>(__u));
1838 template<__eligible_tuple_like<tuple> _UTuple>
1839 requires (__const_assignable_from_tuple_like<_UTuple>())
1840 constexpr const tuple&
1841 operator=(_UTuple&& __u) const
1843 this->_M_assign(__tuple_like_tag_t{}, std::forward<_UTuple>(__u));
1847 template<__tuple_like _UTuple>
1848 requires (!__is_tuple_v<_UTuple>)
1849 friend constexpr bool
1850 operator== [[nodiscard]] (const tuple& __t, const _UTuple& __u)
1852 static_assert(sizeof...(_Elements) == tuple_size_v<_UTuple>,
1853 "tuple objects can only be compared if they have equal sizes.");
1854 return [&]<size_t... _Is>(index_sequence<_Is...>) {
1855 return (bool(std::get<_Is>(__t) == std::get<_Is>(__u))
1857 }(index_sequence_for<_Elements...>{});
1860 template<__tuple_like _UTuple,
1861 typename = make_index_sequence<tuple_size_v<_UTuple>>>
1862 struct __tuple_like_common_comparison_category;
1864 template<__tuple_like _UTuple, size_t... _Is>
1866 { typename void_t<__detail::__synth3way_t<_Elements, tuple_element_t<_Is, _UTuple>>...>; }
1867 struct __tuple_like_common_comparison_category<_UTuple, index_sequence<_Is...>>
1869 using type = common_comparison_category_t
1870 <__detail::__synth3way_t<_Elements, tuple_element_t<_Is, _UTuple>>...>;
1873 template<__tuple_like _UTuple>
1874 requires (!__is_tuple_v<_UTuple>)
1875 friend constexpr typename __tuple_like_common_comparison_category<_UTuple>::type
1876 operator<=>(const tuple& __t, const _UTuple& __u)
1878 using _Cat = typename __tuple_like_common_comparison_category<_UTuple>::type;
1879 return std::__tuple_cmp<_Cat>(__t, __u, index_sequence_for<_Elements...>());
1883#else // ! (concepts && consteval)
1886 template<typename... _UElements>
1888 __enable_if_t<sizeof...(_UElements) == sizeof...(_Elements), bool>
1890 { return __and_<is_assignable<_Elements&, _UElements>...>::value; }
1892 // Condition for noexcept-specifier of an assignment operator.
1893 template<typename... _UElements>
1894 static constexpr bool __nothrow_assignable()
1897 __and_<is_nothrow_assignable<_Elements&, _UElements>...>::value;
1902 _GLIBCXX20_CONSTEXPR
1904 operator=(__conditional_t<__assignable<const _Elements&...>(),
1906 const __nonesuch&> __in)
1907 noexcept(__nothrow_assignable<const _Elements&...>())
1909 this->_M_assign(__in);
1913 _GLIBCXX20_CONSTEXPR
1915 operator=(__conditional_t<__assignable<_Elements...>(),
1918 noexcept(__nothrow_assignable<_Elements...>())
1920 this->_M_assign(std::move(__in));
1924 template<typename... _UElements>
1925 _GLIBCXX20_CONSTEXPR
1926 __enable_if_t<__assignable<const _UElements&...>(), tuple&>
1927 operator=(const tuple<_UElements...>& __in)
1928 noexcept(__nothrow_assignable<const _UElements&...>())
1930 this->_M_assign(__in);
1934 template<typename... _UElements>
1935 _GLIBCXX20_CONSTEXPR
1936 __enable_if_t<__assignable<_UElements...>(), tuple&>
1937 operator=(tuple<_UElements...>&& __in)
1938 noexcept(__nothrow_assignable<_UElements...>())
1940 this->_M_assign(std::move(__in));
1943#endif // concepts && consteval
1946 _GLIBCXX20_CONSTEXPR
1949 noexcept(__and_<__is_nothrow_swappable<_Elements>...>::value)
1950 { _Inherited::_M_swap(__in); }
1952#if __cpp_lib_ranges_zip // >= C++23
1953 // As an extension, we constrain the const swap member function in order
1954 // to continue accepting explicit instantiation of tuples whose elements
1955 // are not all const swappable. Without this constraint, such an
1956 // explicit instantiation would also instantiate the ill-formed body of
1957 // this function and yield a hard error. This constraint shouldn't
1958 // affect the behavior of valid programs.
1960 swap(const tuple& __in) const
1961 noexcept(__and_v<__is_nothrow_swappable<const _Elements>...>)
1962 requires (is_swappable_v<const _Elements> && ...)
1963 { _Inherited::_M_swap(__in); }
1967#if __cpp_deduction_guides >= 201606
1968 template<typename... _UTypes>
1969 tuple(_UTypes...) -> tuple<_UTypes...>;
1970 template<typename _T1, typename _T2>
1971 tuple(pair<_T1, _T2>) -> tuple<_T1, _T2>;
1972 template<typename _Alloc, typename... _UTypes>
1973 tuple(allocator_arg_t, _Alloc, _UTypes...) -> tuple<_UTypes...>;
1974 template<typename _Alloc, typename _T1, typename _T2>
1975 tuple(allocator_arg_t, _Alloc, pair<_T1, _T2>) -> tuple<_T1, _T2>;
1976 template<typename _Alloc, typename... _UTypes>
1977 tuple(allocator_arg_t, _Alloc, tuple<_UTypes...>) -> tuple<_UTypes...>;
1980 // Explicit specialization, zero-element tuple.
1985 _GLIBCXX20_CONSTEXPR
1986 void swap(tuple&) noexcept { /* no-op */ }
1987#if __cpp_lib_ranges_zip // >= C++23
1988 constexpr void swap(const tuple&) const noexcept { /* no-op */ }
1990 // We need the default since we're going to define no-op
1991 // allocator constructors.
1993 // No-op allocator constructors.
1994 template<typename _Alloc>
1995 _GLIBCXX20_CONSTEXPR
1996 tuple(allocator_arg_t, const _Alloc&) noexcept { }
1997 template<typename _Alloc>
1998 _GLIBCXX20_CONSTEXPR
1999 tuple(allocator_arg_t, const _Alloc&, const tuple&) noexcept { }
2002#if !(__cpp_concepts && __cpp_consteval && __cpp_conditional_explicit) // !C++20
2003 /// Partial specialization, 2-element tuple.
2004 /// Includes construction and assignment from a pair.
2005 template<typename _T1, typename _T2>
2006 class tuple<_T1, _T2> : public _Tuple_impl<0, _T1, _T2>
2008 typedef _Tuple_impl<0, _T1, _T2> _Inherited;
2010 // Constraint for non-explicit default constructor
2011 template<bool _Dummy, typename _U1, typename _U2>
2012 using _ImplicitDefaultCtor = __enable_if_t<
2013 _TupleConstraints<_Dummy, _U1, _U2>::
2014 __is_implicitly_default_constructible(),
2017 // Constraint for explicit default constructor
2018 template<bool _Dummy, typename _U1, typename _U2>
2019 using _ExplicitDefaultCtor = __enable_if_t<
2020 _TupleConstraints<_Dummy, _U1, _U2>::
2021 __is_explicitly_default_constructible(),
2024 template<bool _Dummy>
2025 using _TCC = _TupleConstraints<_Dummy, _T1, _T2>;
2027 // Constraint for non-explicit constructors
2028 template<bool _Cond, typename _U1, typename _U2>
2029 using _ImplicitCtor = __enable_if_t<
2030 _TCC<_Cond>::template __is_implicitly_constructible<_U1, _U2>(),
2033 // Constraint for non-explicit constructors
2034 template<bool _Cond, typename _U1, typename _U2>
2035 using _ExplicitCtor = __enable_if_t<
2036 _TCC<_Cond>::template __is_explicitly_constructible<_U1, _U2>(),
2039 template<typename _U1, typename _U2>
2040 static constexpr bool __assignable()
2042 return __and_<is_assignable<_T1&, _U1>,
2043 is_assignable<_T2&, _U2>>::value;
2046 template<typename _U1, typename _U2>
2047 static constexpr bool __nothrow_assignable()
2049 return __and_<is_nothrow_assignable<_T1&, _U1>,
2050 is_nothrow_assignable<_T2&, _U2>>::value;
2053 template<typename _U1, typename _U2>
2054 static constexpr bool __nothrow_constructible()
2056 return __and_<is_nothrow_constructible<_T1, _U1>,
2057 is_nothrow_constructible<_T2, _U2>>::value;
2060 static constexpr bool __nothrow_default_constructible()
2062 return __and_<is_nothrow_default_constructible<_T1>,
2063 is_nothrow_default_constructible<_T2>>::value;
2066 template<typename _U1>
2067 static constexpr bool __is_alloc_arg()
2068 { return is_same<__remove_cvref_t<_U1>, allocator_arg_t>::value; }
2070 /// @cond undocumented
2071#undef __glibcxx_no_dangling_refs
2072 // Error if construction from _U1 and _U2 would create a dangling ref.
2073#if __has_builtin(__reference_constructs_from_temporary) \
2074 && defined _GLIBCXX_DEBUG
2075# define __glibcxx_no_dangling_refs(_U1, _U2) \
2076 static_assert(!__reference_constructs_from_temporary(_T1, _U1) \
2077 && !__reference_constructs_from_temporary(_T2, _U2), \
2078 "std::tuple constructor creates a dangling reference")
2080# define __glibcxx_no_dangling_refs(_U1, _U2)
2085 template<bool _Dummy = true,
2086 _ImplicitDefaultCtor<_Dummy, _T1, _T2> = true>
2089 noexcept(__nothrow_default_constructible())
2092 template<bool _Dummy = true,
2093 _ExplicitDefaultCtor<_Dummy, _T1, _T2> = false>
2096 noexcept(__nothrow_default_constructible())
2099 template<bool _Dummy = true,
2100 _ImplicitCtor<_Dummy, const _T1&, const _T2&> = true>
2102 tuple(const _T1& __a1, const _T2& __a2)
2103 noexcept(__nothrow_constructible<const _T1&, const _T2&>())
2104 : _Inherited(__a1, __a2) { }
2106 template<bool _Dummy = true,
2107 _ExplicitCtor<_Dummy, const _T1&, const _T2&> = false>
2109 tuple(const _T1& __a1, const _T2& __a2)
2110 noexcept(__nothrow_constructible<const _T1&, const _T2&>())
2111 : _Inherited(__a1, __a2) { }
2113 template<typename _U1, typename _U2,
2114 _ImplicitCtor<!__is_alloc_arg<_U1>(), _U1, _U2> = true>
2116 tuple(_U1&& __a1, _U2&& __a2)
2117 noexcept(__nothrow_constructible<_U1, _U2>())
2118 : _Inherited(std::forward<_U1>(__a1), std::forward<_U2>(__a2))
2119 { __glibcxx_no_dangling_refs(_U1&&, _U2&&); }
2121 template<typename _U1, typename _U2,
2122 _ExplicitCtor<!__is_alloc_arg<_U1>(), _U1, _U2> = false>
2124 tuple(_U1&& __a1, _U2&& __a2)
2125 noexcept(__nothrow_constructible<_U1, _U2>())
2126 : _Inherited(std::forward<_U1>(__a1), std::forward<_U2>(__a2))
2127 { __glibcxx_no_dangling_refs(_U1&&, _U2&&); }
2129 constexpr tuple(const tuple&) = default;
2131 constexpr tuple(tuple&&) = default;
2133 template<typename _U1, typename _U2,
2134 _ImplicitCtor<true, const _U1&, const _U2&> = true>
2136 tuple(const tuple<_U1, _U2>& __in)
2137 noexcept(__nothrow_constructible<const _U1&, const _U2&>())
2138 : _Inherited(static_cast<const _Tuple_impl<0, _U1, _U2>&>(__in))
2139 { __glibcxx_no_dangling_refs(const _U1&, const _U2&); }
2141 template<typename _U1, typename _U2,
2142 _ExplicitCtor<true, const _U1&, const _U2&> = false>
2144 tuple(const tuple<_U1, _U2>& __in)
2145 noexcept(__nothrow_constructible<const _U1&, const _U2&>())
2146 : _Inherited(static_cast<const _Tuple_impl<0, _U1, _U2>&>(__in))
2147 { __glibcxx_no_dangling_refs(const _U1&, const _U2&); }
2149 template<typename _U1, typename _U2,
2150 _ImplicitCtor<true, _U1, _U2> = true>
2152 tuple(tuple<_U1, _U2>&& __in)
2153 noexcept(__nothrow_constructible<_U1, _U2>())
2154 : _Inherited(static_cast<_Tuple_impl<0, _U1, _U2>&&>(__in))
2155 { __glibcxx_no_dangling_refs(_U1&&, _U2&&); }
2157 template<typename _U1, typename _U2,
2158 _ExplicitCtor<true, _U1, _U2> = false>
2160 tuple(tuple<_U1, _U2>&& __in)
2161 noexcept(__nothrow_constructible<_U1, _U2>())
2162 : _Inherited(static_cast<_Tuple_impl<0, _U1, _U2>&&>(__in))
2163 { __glibcxx_no_dangling_refs(_U1&&, _U2&&); }
2165 template<typename _U1, typename _U2,
2166 _ImplicitCtor<true, const _U1&, const _U2&> = true>
2168 tuple(const pair<_U1, _U2>& __in)
2169 noexcept(__nothrow_constructible<const _U1&, const _U2&>())
2170 : _Inherited(__in.first, __in.second)
2171 { __glibcxx_no_dangling_refs(const _U1&, const _U2&); }
2173 template<typename _U1, typename _U2,
2174 _ExplicitCtor<true, const _U1&, const _U2&> = false>
2176 tuple(const pair<_U1, _U2>& __in)
2177 noexcept(__nothrow_constructible<const _U1&, const _U2&>())
2178 : _Inherited(__in.first, __in.second)
2179 { __glibcxx_no_dangling_refs(const _U1&, const _U2&); }
2181 template<typename _U1, typename _U2,
2182 _ImplicitCtor<true, _U1, _U2> = true>
2184 tuple(pair<_U1, _U2>&& __in)
2185 noexcept(__nothrow_constructible<_U1, _U2>())
2186 : _Inherited(std::forward<_U1>(__in.first),
2187 std::forward<_U2>(__in.second))
2188 { __glibcxx_no_dangling_refs(_U1&&, _U2&&); }
2190 template<typename _U1, typename _U2,
2191 _ExplicitCtor<true, _U1, _U2> = false>
2193 tuple(pair<_U1, _U2>&& __in)
2194 noexcept(__nothrow_constructible<_U1, _U2>())
2195 : _Inherited(std::forward<_U1>(__in.first),
2196 std::forward<_U2>(__in.second))
2197 { __glibcxx_no_dangling_refs(_U1&&, _U2&&); }
2199 // Allocator-extended constructors.
2201 template<typename _Alloc,
2202 _ImplicitDefaultCtor<is_object<_Alloc>::value, _T1, _T2> = true>
2203 _GLIBCXX20_CONSTEXPR
2204 tuple(allocator_arg_t __tag, const _Alloc& __a)
2205 : _Inherited(__tag, __a) { }
2207 template<typename _Alloc,
2208 _ExplicitDefaultCtor<is_object<_Alloc>::value, _T1, _T2> = false>
2209 _GLIBCXX20_CONSTEXPR
2211 tuple(allocator_arg_t __tag, const _Alloc& __a)
2212 : _Inherited(__tag, __a) { }
2214 template<typename _Alloc, bool _Dummy = true,
2215 _ImplicitCtor<_Dummy, const _T1&, const _T2&> = true>
2216 _GLIBCXX20_CONSTEXPR
2217 tuple(allocator_arg_t __tag, const _Alloc& __a,
2218 const _T1& __a1, const _T2& __a2)
2219 : _Inherited(__tag, __a, __a1, __a2) { }
2221 template<typename _Alloc, bool _Dummy = true,
2222 _ExplicitCtor<_Dummy, const _T1&, const _T2&> = false>
2224 _GLIBCXX20_CONSTEXPR
2225 tuple(allocator_arg_t __tag, const _Alloc& __a,
2226 const _T1& __a1, const _T2& __a2)
2227 : _Inherited(__tag, __a, __a1, __a2) { }
2229 template<typename _Alloc, typename _U1, typename _U2,
2230 _ImplicitCtor<true, _U1, _U2> = true>
2231 _GLIBCXX20_CONSTEXPR
2232 tuple(allocator_arg_t __tag, const _Alloc& __a, _U1&& __a1, _U2&& __a2)
2233 : _Inherited(__tag, __a, std::forward<_U1>(__a1),
2234 std::forward<_U2>(__a2))
2235 { __glibcxx_no_dangling_refs(_U1&&, _U2&&); }
2237 template<typename _Alloc, typename _U1, typename _U2,
2238 _ExplicitCtor<true, _U1, _U2> = false>
2240 _GLIBCXX20_CONSTEXPR
2241 tuple(allocator_arg_t __tag, const _Alloc& __a,
2242 _U1&& __a1, _U2&& __a2)
2243 : _Inherited(__tag, __a, std::forward<_U1>(__a1),
2244 std::forward<_U2>(__a2))
2245 { __glibcxx_no_dangling_refs(_U1&&, _U2&&); }
2247 template<typename _Alloc>
2248 _GLIBCXX20_CONSTEXPR
2249 tuple(allocator_arg_t __tag, const _Alloc& __a, const tuple& __in)
2250 : _Inherited(__tag, __a, static_cast<const _Inherited&>(__in)) { }
2252 template<typename _Alloc>
2253 _GLIBCXX20_CONSTEXPR
2254 tuple(allocator_arg_t __tag, const _Alloc& __a, tuple&& __in)
2255 : _Inherited(__tag, __a, static_cast<_Inherited&&>(__in)) { }
2257 template<typename _Alloc, typename _U1, typename _U2,
2258 _ImplicitCtor<true, const _U1&, const _U2&> = true>
2259 _GLIBCXX20_CONSTEXPR
2260 tuple(allocator_arg_t __tag, const _Alloc& __a,
2261 const tuple<_U1, _U2>& __in)
2262 : _Inherited(__tag, __a,
2263 static_cast<const _Tuple_impl<0, _U1, _U2>&>(__in))
2264 { __glibcxx_no_dangling_refs(const _U1&, const _U2&); }
2266 template<typename _Alloc, typename _U1, typename _U2,
2267 _ExplicitCtor<true, const _U1&, const _U2&> = false>
2269 _GLIBCXX20_CONSTEXPR
2270 tuple(allocator_arg_t __tag, const _Alloc& __a,
2271 const tuple<_U1, _U2>& __in)
2272 : _Inherited(__tag, __a,
2273 static_cast<const _Tuple_impl<0, _U1, _U2>&>(__in))
2274 { __glibcxx_no_dangling_refs(const _U1&, const _U2&); }
2276 template<typename _Alloc, typename _U1, typename _U2,
2277 _ImplicitCtor<true, _U1, _U2> = true>
2278 _GLIBCXX20_CONSTEXPR
2279 tuple(allocator_arg_t __tag, const _Alloc& __a, tuple<_U1, _U2>&& __in)
2280 : _Inherited(__tag, __a, static_cast<_Tuple_impl<0, _U1, _U2>&&>(__in))
2281 { __glibcxx_no_dangling_refs(_U1&&, _U2&&); }
2283 template<typename _Alloc, typename _U1, typename _U2,
2284 _ExplicitCtor<true, _U1, _U2> = false>
2286 _GLIBCXX20_CONSTEXPR
2287 tuple(allocator_arg_t __tag, const _Alloc& __a, tuple<_U1, _U2>&& __in)
2288 : _Inherited(__tag, __a, static_cast<_Tuple_impl<0, _U1, _U2>&&>(__in))
2289 { __glibcxx_no_dangling_refs(_U1&&, _U2&&); }
2291 template<typename _Alloc, typename _U1, typename _U2,
2292 _ImplicitCtor<true, const _U1&, const _U2&> = true>
2293 _GLIBCXX20_CONSTEXPR
2294 tuple(allocator_arg_t __tag, const _Alloc& __a,
2295 const pair<_U1, _U2>& __in)
2296 : _Inherited(__tag, __a, __in.first, __in.second)
2297 { __glibcxx_no_dangling_refs(const _U1&, const _U2&); }
2299 template<typename _Alloc, typename _U1, typename _U2,
2300 _ExplicitCtor<true, const _U1&, const _U2&> = false>
2302 _GLIBCXX20_CONSTEXPR
2303 tuple(allocator_arg_t __tag, const _Alloc& __a,
2304 const pair<_U1, _U2>& __in)
2305 : _Inherited(__tag, __a, __in.first, __in.second)
2306 { __glibcxx_no_dangling_refs(const _U1&, const _U2&); }
2308 template<typename _Alloc, typename _U1, typename _U2,
2309 _ImplicitCtor<true, _U1, _U2> = true>
2310 _GLIBCXX20_CONSTEXPR
2311 tuple(allocator_arg_t __tag, const _Alloc& __a, pair<_U1, _U2>&& __in)
2312 : _Inherited(__tag, __a, std::forward<_U1>(__in.first),
2313 std::forward<_U2>(__in.second))
2314 { __glibcxx_no_dangling_refs(_U1&&, _U2&&); }
2316 template<typename _Alloc, typename _U1, typename _U2,
2317 _ExplicitCtor<true, _U1, _U2> = false>
2319 _GLIBCXX20_CONSTEXPR
2320 tuple(allocator_arg_t __tag, const _Alloc& __a, pair<_U1, _U2>&& __in)
2321 : _Inherited(__tag, __a, std::forward<_U1>(__in.first),
2322 std::forward<_U2>(__in.second))
2323 { __glibcxx_no_dangling_refs(_U1&&, _U2&&); }
2325 // Tuple assignment.
2327 _GLIBCXX20_CONSTEXPR
2329 operator=(__conditional_t<__assignable<const _T1&, const _T2&>(),
2331 const __nonesuch&> __in)
2332 noexcept(__nothrow_assignable<const _T1&, const _T2&>())
2334 this->_M_assign(__in);
2338 _GLIBCXX20_CONSTEXPR
2340 operator=(__conditional_t<__assignable<_T1, _T2>(),
2343 noexcept(__nothrow_assignable<_T1, _T2>())
2345 this->_M_assign(std::move(__in));
2349 template<typename _U1, typename _U2>
2350 _GLIBCXX20_CONSTEXPR
2351 __enable_if_t<__assignable<const _U1&, const _U2&>(), tuple&>
2352 operator=(const tuple<_U1, _U2>& __in)
2353 noexcept(__nothrow_assignable<const _U1&, const _U2&>())
2355 this->_M_assign(__in);
2359 template<typename _U1, typename _U2>
2360 _GLIBCXX20_CONSTEXPR
2361 __enable_if_t<__assignable<_U1, _U2>(), tuple&>
2362 operator=(tuple<_U1, _U2>&& __in)
2363 noexcept(__nothrow_assignable<_U1, _U2>())
2365 this->_M_assign(std::move(__in));
2369 template<typename _U1, typename _U2>
2370 _GLIBCXX20_CONSTEXPR
2371 __enable_if_t<__assignable<const _U1&, const _U2&>(), tuple&>
2372 operator=(const pair<_U1, _U2>& __in)
2373 noexcept(__nothrow_assignable<const _U1&, const _U2&>())
2375 this->_M_head(*this) = __in.first;
2376 this->_M_tail(*this)._M_head(*this) = __in.second;
2380 template<typename _U1, typename _U2>
2381 _GLIBCXX20_CONSTEXPR
2382 __enable_if_t<__assignable<_U1, _U2>(), tuple&>
2383 operator=(pair<_U1, _U2>&& __in)
2384 noexcept(__nothrow_assignable<_U1, _U2>())
2386 this->_M_head(*this) = std::forward<_U1>(__in.first);
2387 this->_M_tail(*this)._M_head(*this) = std::forward<_U2>(__in.second);
2391 _GLIBCXX20_CONSTEXPR
2394 noexcept(__and_<__is_nothrow_swappable<_T1>,
2395 __is_nothrow_swappable<_T2>>::value)
2396 { _Inherited::_M_swap(__in); }
2398#endif // concepts && conditional_explicit
2400 /// class tuple_size
2401 template<typename... _Elements>
2402 struct tuple_size<tuple<_Elements...>>
2403 : public integral_constant<size_t, sizeof...(_Elements)> { };
2405#if __cplusplus >= 201703L
2406 template<typename... _Types>
2407 inline constexpr size_t tuple_size_v<tuple<_Types...>>
2408 = sizeof...(_Types);
2410 template<typename... _Types>
2411 inline constexpr size_t tuple_size_v<const tuple<_Types...>>
2412 = sizeof...(_Types);
2415 /// Trait to get the Ith element type from a tuple.
2416 template<size_t __i, typename... _Types>
2417 struct tuple_element<__i, tuple<_Types...>>
2419 static_assert(__i < sizeof...(_Types), "tuple index must be in range");
2421 using type = typename _Nth_type<__i, _Types...>::type;
2424 template<size_t __i, typename _Head, typename... _Tail>
2426 __get_helper(_Tuple_impl<__i, _Head, _Tail...>& __t) noexcept
2427 { return _Tuple_impl<__i, _Head, _Tail...>::_M_head(__t); }
2429 template<size_t __i, typename _Head, typename... _Tail>
2430 constexpr const _Head&
2431 __get_helper(const _Tuple_impl<__i, _Head, _Tail...>& __t) noexcept
2432 { return _Tuple_impl<__i, _Head, _Tail...>::_M_head(__t); }
2434 // Deleted overload to improve diagnostics for invalid indices
2435 template<size_t __i, typename... _Types>
2436 __enable_if_t<(__i >= sizeof...(_Types))>
2437 __get_helper(const tuple<_Types...>&) = delete;
2439 /// Return a reference to the ith element of a tuple.
2440 template<size_t __i, typename... _Elements>
2441 constexpr __tuple_element_t<__i, tuple<_Elements...>>&
2442 get(tuple<_Elements...>& __t) noexcept
2443 { return std::__get_helper<__i>(__t); }
2445 /// Return a const reference to the ith element of a const tuple.
2446 template<size_t __i, typename... _Elements>
2447 constexpr const __tuple_element_t<__i, tuple<_Elements...>>&
2448 get(const tuple<_Elements...>& __t) noexcept
2449 { return std::__get_helper<__i>(__t); }
2451 /// Return an rvalue reference to the ith element of a tuple rvalue.
2452 template<size_t __i, typename... _Elements>
2453 constexpr __tuple_element_t<__i, tuple<_Elements...>>&&
2454 get(tuple<_Elements...>&& __t) noexcept
2456 typedef __tuple_element_t<__i, tuple<_Elements...>> __element_type;
2457 return std::forward<__element_type>(std::__get_helper<__i>(__t));
2460 /// Return a const rvalue reference to the ith element of a const tuple rvalue.
2461 template<size_t __i, typename... _Elements>
2462 constexpr const __tuple_element_t<__i, tuple<_Elements...>>&&
2463 get(const tuple<_Elements...>&& __t) noexcept
2465 typedef __tuple_element_t<__i, tuple<_Elements...>> __element_type;
2466 return std::forward<const __element_type>(std::__get_helper<__i>(__t));
2469 /// @cond undocumented
2470 // Deleted overload chosen for invalid indices.
2471 template<size_t __i, typename... _Elements>
2472 constexpr __enable_if_t<(__i >= sizeof...(_Elements))>
2473 get(const tuple<_Elements...>&) = delete;
2476#ifdef __cpp_lib_tuples_by_type // C++ >= 14
2477 /// Return a reference to the unique element of type _Tp of a tuple.
2478 template <typename _Tp, typename... _Types>
2480 get(tuple<_Types...>& __t) noexcept
2482 constexpr size_t __idx = __find_uniq_type_in_pack<_Tp, _Types...>();
2483 static_assert(__idx < sizeof...(_Types),
2484 "the type T in std::get<T> must occur exactly once in the tuple");
2485 return std::__get_helper<__idx>(__t);
2488 /// Return a reference to the unique element of type _Tp of a tuple rvalue.
2489 template <typename _Tp, typename... _Types>
2491 get(tuple<_Types...>&& __t) noexcept
2493 constexpr size_t __idx = __find_uniq_type_in_pack<_Tp, _Types...>();
2494 static_assert(__idx < sizeof...(_Types),
2495 "the type T in std::get<T> must occur exactly once in the tuple");
2496 return std::forward<_Tp>(std::__get_helper<__idx>(__t));
2499 /// Return a const reference to the unique element of type _Tp of a tuple.
2500 template <typename _Tp, typename... _Types>
2501 constexpr const _Tp&
2502 get(const tuple<_Types...>& __t) noexcept
2504 constexpr size_t __idx = __find_uniq_type_in_pack<_Tp, _Types...>();
2505 static_assert(__idx < sizeof...(_Types),
2506 "the type T in std::get<T> must occur exactly once in the tuple");
2507 return std::__get_helper<__idx>(__t);
2510 /// Return a const reference to the unique element of type _Tp of
2511 /// a const tuple rvalue.
2512 template <typename _Tp, typename... _Types>
2513 constexpr const _Tp&&
2514 get(const tuple<_Types...>&& __t) noexcept
2516 constexpr size_t __idx = __find_uniq_type_in_pack<_Tp, _Types...>();
2517 static_assert(__idx < sizeof...(_Types),
2518 "the type T in std::get<T> must occur exactly once in the tuple");
2519 return std::forward<const _Tp>(std::__get_helper<__idx>(__t));
2523#if __cpp_lib_three_way_comparison
2524 template<typename... _Tps, typename... _Ups>
2525 requires (sizeof...(_Tps) == sizeof...(_Ups))
2526 && (requires (const _Tps& __t, const _Ups& __u) {
2527 { __t == __u } -> __detail::__boolean_testable;
2530 operator== [[nodiscard]] (const tuple<_Tps...>& __t,
2531 const tuple<_Ups...>& __u)
2533 return [&]<size_t... _Inds>(index_sequence<_Inds...>) {
2534 // Fold == over the tuples until non-equal elements are found.
2535 return ((std::get<_Inds>(__t) == std::get<_Inds>(__u)) && ...);
2536 }(index_sequence_for<_Tps...>{});
2539 template<typename _Cat, typename _Tp, typename _Up, typename _IndexSeq>
2542 __tuple_cmp(const _Tp& __t, const _Up& __u, _IndexSeq __indices)
2544 _Cat __c = _Cat::equivalent;
2546 // Set __c to the comparison result of two corresponding elements.
2547 // Return true they are equivalent.
2548 auto __cmp = [&]<size_t _Ind>(integral_constant<size_t, _Ind>) {
2549 __c = __detail::__synth3way(std::get<_Ind>(__t), std::get<_Ind>(__u));
2553 [&]<size_t... _Inds>(index_sequence<_Inds...>) {
2554 // Fold __cmp over the tuples until non-equivalent elements are found.
2555 (void)(__cmp(integral_constant<size_t, _Inds>{}) && ...);
2561 template<typename... _Tps, typename... _Ups>
2562 requires (sizeof...(_Tps) == sizeof...(_Ups))
2563 && (requires { typename __detail::__synth3way_t<_Tps, _Ups>; } && ...)
2565 common_comparison_category_t<__detail::__synth3way_t<_Tps, _Ups>...>
2566 operator<=> [[nodiscard]] (const tuple<_Tps...>& __t,
2567 const tuple<_Ups...>& __u)
2570 = common_comparison_category_t<__detail::__synth3way_t<_Tps, _Ups>...>;
2571 return std::__tuple_cmp<_Cat>(__t, __u, index_sequence_for<_Tps...>());
2575 // This class performs the comparison operations on tuples
2576 template<typename _Tp, typename _Up, size_t __i, size_t __size>
2577 struct __tuple_compare
2579 static constexpr bool
2580 __eq(const _Tp& __t, const _Up& __u)
2582 return bool(std::get<__i>(__t) == std::get<__i>(__u))
2583 && __tuple_compare<_Tp, _Up, __i + 1, __size>::__eq(__t, __u);
2586 static constexpr bool
2587 __less(const _Tp& __t, const _Up& __u)
2589 return bool(std::get<__i>(__t) < std::get<__i>(__u))
2590 || (!bool(std::get<__i>(__u) < std::get<__i>(__t))
2591 && __tuple_compare<_Tp, _Up, __i + 1, __size>::__less(__t, __u));
2595 template<typename _Tp, typename _Up, size_t __size>
2596 struct __tuple_compare<_Tp, _Up, __size, __size>
2598 static constexpr bool
2599 __eq(const _Tp&, const _Up&) { return true; }
2601 static constexpr bool
2602 __less(const _Tp&, const _Up&) { return false; }
2605 template<typename... _TElements, typename... _UElements>
2608 operator==(const tuple<_TElements...>& __t,
2609 const tuple<_UElements...>& __u)
2611 static_assert(sizeof...(_TElements) == sizeof...(_UElements),
2612 "tuple objects can only be compared if they have equal sizes.");
2613 using __compare = __tuple_compare<tuple<_TElements...>,
2614 tuple<_UElements...>,
2615 0, sizeof...(_TElements)>;
2616 return __compare::__eq(__t, __u);
2619 template<typename... _TElements, typename... _UElements>
2622 operator<(const tuple<_TElements...>& __t,
2623 const tuple<_UElements...>& __u)
2625 static_assert(sizeof...(_TElements) == sizeof...(_UElements),
2626 "tuple objects can only be compared if they have equal sizes.");
2627 using __compare = __tuple_compare<tuple<_TElements...>,
2628 tuple<_UElements...>,
2629 0, sizeof...(_TElements)>;
2630 return __compare::__less(__t, __u);
2633 template<typename... _TElements, typename... _UElements>
2636 operator!=(const tuple<_TElements...>& __t,
2637 const tuple<_UElements...>& __u)
2638 { return !(__t == __u); }
2640 template<typename... _TElements, typename... _UElements>
2643 operator>(const tuple<_TElements...>& __t,
2644 const tuple<_UElements...>& __u)
2645 { return __u < __t; }
2647 template<typename... _TElements, typename... _UElements>
2650 operator<=(const tuple<_TElements...>& __t,
2651 const tuple<_UElements...>& __u)
2652 { return !(__u < __t); }
2654 template<typename... _TElements, typename... _UElements>
2657 operator>=(const tuple<_TElements...>& __t,
2658 const tuple<_UElements...>& __u)
2659 { return !(__t < __u); }
2660#endif // three_way_comparison
2663 /// Create a tuple containing copies of the arguments
2664 template<typename... _Elements>
2665 constexpr tuple<typename __decay_and_strip<_Elements>::__type...>
2666 make_tuple(_Elements&&... __args)
2668 typedef tuple<typename __decay_and_strip<_Elements>::__type...>
2670 return __result_type(std::forward<_Elements>(__args)...);
2673 // _GLIBCXX_RESOLVE_LIB_DEFECTS
2674 // 2275. Why is forward_as_tuple not constexpr?
2675 /// Create a tuple of lvalue or rvalue references to the arguments
2676 template<typename... _Elements>
2677 constexpr tuple<_Elements&&...>
2678 forward_as_tuple(_Elements&&... __args) noexcept
2679 { return tuple<_Elements&&...>(std::forward<_Elements>(__args)...); }
2681 /// @cond undocumented
2682 template<size_t, typename, typename, size_t>
2683 struct __make_tuple_impl;
2685 template<size_t _Idx, typename _Tuple, typename... _Tp, size_t _Nm>
2686 struct __make_tuple_impl<_Idx, tuple<_Tp...>, _Tuple, _Nm>
2687 : __make_tuple_impl<_Idx + 1,
2688 tuple<_Tp..., __tuple_element_t<_Idx, _Tuple>>,
2692 template<size_t _Nm, typename _Tuple, typename... _Tp>
2693 struct __make_tuple_impl<_Nm, tuple<_Tp...>, _Tuple, _Nm>
2695 typedef tuple<_Tp...> __type;
2698 template<typename _Tuple>
2699 struct __do_make_tuple
2700 : __make_tuple_impl<0, tuple<>, _Tuple, tuple_size<_Tuple>::value>
2703 // Returns the std::tuple equivalent of a tuple-like type.
2704 template<typename _Tuple>
2706 : public __do_make_tuple<__remove_cvref_t<_Tuple>>
2709 // Combines several std::tuple's into a single one.
2710 template<typename...>
2711 struct __combine_tuples;
2714 struct __combine_tuples<>
2716 typedef tuple<> __type;
2719 template<typename... _Ts>
2720 struct __combine_tuples<tuple<_Ts...>>
2722 typedef tuple<_Ts...> __type;
2725 template<typename... _T1s, typename... _T2s, typename... _Rem>
2726 struct __combine_tuples<tuple<_T1s...>, tuple<_T2s...>, _Rem...>
2728 typedef typename __combine_tuples<tuple<_T1s..., _T2s...>,
2729 _Rem...>::__type __type;
2732 // Computes the result type of tuple_cat given a set of tuple-like types.
2733 template<typename... _Tpls>
2734 struct __tuple_cat_result
2736 typedef typename __combine_tuples
2737 <typename __make_tuple<_Tpls>::__type...>::__type __type;
2740 // Helper to determine the index set for the first tuple-like
2741 // type of a given set.
2742 template<typename...>
2743 struct __make_1st_indices;
2746 struct __make_1st_indices<>
2748 typedef _Index_tuple<> __type;
2751 template<typename _Tp, typename... _Tpls>
2752 struct __make_1st_indices<_Tp, _Tpls...>
2754 typedef typename _Build_index_tuple<tuple_size<
2755 typename remove_reference<_Tp>::type>::value>::__type __type;
2758 // Performs the actual concatenation by step-wise expanding tuple-like
2759 // objects into the elements, which are finally forwarded into the
2761 template<typename _Ret, typename _Indices, typename... _Tpls>
2762 struct __tuple_concater;
2764 template<typename _Ret, size_t... _Is, typename _Tp, typename... _Tpls>
2765 struct __tuple_concater<_Ret, _Index_tuple<_Is...>, _Tp, _Tpls...>
2767 template<typename... _Us>
2768 static constexpr _Ret
2769 _S_do(_Tp&& __tp, _Tpls&&... __tps, _Us&&... __us)
2771 typedef typename __make_1st_indices<_Tpls...>::__type __idx;
2772 typedef __tuple_concater<_Ret, __idx, _Tpls...> __next;
2773 return __next::_S_do(std::forward<_Tpls>(__tps)...,
2774 std::forward<_Us>(__us)...,
2775 std::get<_Is>(std::forward<_Tp>(__tp))...);
2779 template<typename _Ret>
2780 struct __tuple_concater<_Ret, _Index_tuple<>>
2782 template<typename... _Us>
2783 static constexpr _Ret
2784 _S_do(_Us&&... __us)
2786 return _Ret(std::forward<_Us>(__us)...);
2790 template<typename... _Tps>
2791 struct __is_tuple_like_impl<tuple<_Tps...>> : true_type
2795 /// Create a `tuple` containing all elements from multiple tuple-like objects
2796#if __cpp_lib_tuple_like // >= C++23
2797 template<__tuple_like... _Tpls>
2799 template<typename... _Tpls, typename = typename
2800 enable_if<__and_<__is_tuple_like<_Tpls>...>::value>::type>
2803 tuple_cat(_Tpls&&... __tpls)
2804 -> typename __tuple_cat_result<_Tpls...>::__type
2806 typedef typename __tuple_cat_result<_Tpls...>::__type __ret;
2807 typedef typename __make_1st_indices<_Tpls...>::__type __idx;
2808 typedef __tuple_concater<__ret, __idx, _Tpls...> __concater;
2809 return __concater::_S_do(std::forward<_Tpls>(__tpls)...);
2812 // _GLIBCXX_RESOLVE_LIB_DEFECTS
2813 // 2301. Why is tie not constexpr?
2814 /// Return a tuple of lvalue references bound to the arguments
2815 template<typename... _Elements>
2816 constexpr tuple<_Elements&...>
2817 tie(_Elements&... __args) noexcept
2818 { return tuple<_Elements&...>(__args...); }
2820 /// Exchange the values of two tuples
2821 template<typename... _Elements>
2822 _GLIBCXX20_CONSTEXPR
2824#if __cplusplus > 201402L || !defined(__STRICT_ANSI__) // c++1z or gnu++11
2825 // Constrained free swap overload, see p0185r1
2826 typename enable_if<__and_<__is_swappable<_Elements>...>::value
2831 swap(tuple<_Elements...>& __x, tuple<_Elements...>& __y)
2832 noexcept(noexcept(__x.swap(__y)))
2835#if __cpp_lib_ranges_zip // >= C++23
2836 template<typename... _Elements>
2837 requires (is_swappable_v<const _Elements> && ...)
2839 swap(const tuple<_Elements...>& __x, const tuple<_Elements...>& __y)
2840 noexcept(noexcept(__x.swap(__y)))
2844#if __cplusplus > 201402L || !defined(__STRICT_ANSI__) // c++1z or gnu++11
2845 /// Exchange the values of two const tuples (if const elements can be swapped)
2846 template<typename... _Elements>
2847 _GLIBCXX20_CONSTEXPR
2848 typename enable_if<!__and_<__is_swappable<_Elements>...>::value>::type
2849 swap(tuple<_Elements...>&, tuple<_Elements...>&) = delete;
2852 /// Partial specialization for tuples
2853 template<typename... _Types, typename _Alloc>
2854 struct uses_allocator<tuple<_Types...>, _Alloc> : true_type { };
2856 // See stl_pair.h...
2857 /** "piecewise construction" using a tuple of arguments for each member.
2859 * @param __first Arguments for the first member of the pair.
2860 * @param __second Arguments for the second member of the pair.
2862 * The elements of each tuple will be used as the constructor arguments
2863 * for the data members of the pair.
2865 template<class _T1, class _T2>
2866 template<typename... _Args1, typename... _Args2>
2867 _GLIBCXX20_CONSTEXPR
2870 pair(piecewise_construct_t,
2871 tuple<_Args1...> __first, tuple<_Args2...> __second)
2872 : pair(__first, __second,
2873 typename _Build_index_tuple<sizeof...(_Args1)>::__type(),
2874 typename _Build_index_tuple<sizeof...(_Args2)>::__type())
2877 template<class _T1, class _T2>
2878 template<typename... _Args1, size_t... _Indexes1,
2879 typename... _Args2, size_t... _Indexes2>
2880 _GLIBCXX20_CONSTEXPR inline
2882 pair(tuple<_Args1...>& __tuple1, tuple<_Args2...>& __tuple2,
2883 _Index_tuple<_Indexes1...>, _Index_tuple<_Indexes2...>)
2884 : first(std::forward<_Args1>(std::get<_Indexes1>(__tuple1))...),
2885 second(std::forward<_Args2>(std::get<_Indexes2>(__tuple2))...)
2888#if defined(__cpp_lib_apply) || defined(__cpp_lib_make_from_tuple) // C++ >= 17
2889 // Unpack a std::tuple into a type trait and use its value.
2890 // For cv std::tuple<_Up> the result is _Trait<_Tp, cv _Up...>::value.
2891 // For cv std::tuple<_Up>& the result is _Trait<_Tp, cv _Up&...>::value.
2892 // Otherwise the result is false (because we don't know if std::get throws).
2893 template<template<typename...> class _Trait, typename _Tp, typename _Tuple>
2894 inline constexpr bool __unpack_std_tuple = false;
2896 template<template<typename...> class _Trait, typename _Tp, typename... _Up>
2897 inline constexpr bool __unpack_std_tuple<_Trait, _Tp, tuple<_Up...>>
2898 = _Trait<_Tp, _Up...>::value;
2900 template<template<typename...> class _Trait, typename _Tp, typename... _Up>
2901 inline constexpr bool __unpack_std_tuple<_Trait, _Tp, tuple<_Up...>&>
2902 = _Trait<_Tp, _Up&...>::value;
2904 template<template<typename...> class _Trait, typename _Tp, typename... _Up>
2905 inline constexpr bool __unpack_std_tuple<_Trait, _Tp, const tuple<_Up...>>
2906 = _Trait<_Tp, const _Up...>::value;
2908 template<template<typename...> class _Trait, typename _Tp, typename... _Up>
2909 inline constexpr bool __unpack_std_tuple<_Trait, _Tp, const tuple<_Up...>&>
2910 = _Trait<_Tp, const _Up&...>::value;
2913#ifdef __cpp_lib_apply // C++ >= 17
2914 template <typename _Fn, typename _Tuple, size_t... _Idx>
2915 constexpr decltype(auto)
2916 __apply_impl(_Fn&& __f, _Tuple&& __t, index_sequence<_Idx...>)
2918 return std::__invoke(std::forward<_Fn>(__f),
2919 std::get<_Idx>(std::forward<_Tuple>(__t))...);
2922#if __cpp_lib_tuple_like // >= C++23
2923 template <typename _Fn, __tuple_like _Tuple>
2925 template <typename _Fn, typename _Tuple>
2927 constexpr decltype(auto)
2928 apply(_Fn&& __f, _Tuple&& __t)
2929 noexcept(__unpack_std_tuple<is_nothrow_invocable, _Fn, _Tuple>)
2932 = make_index_sequence<tuple_size_v<remove_reference_t<_Tuple>>>;
2933 return std::__apply_impl(std::forward<_Fn>(__f),
2934 std::forward<_Tuple>(__t),
2939#ifdef __cpp_lib_make_from_tuple // C++ >= 17
2940 template <typename _Tp, typename _Tuple, size_t... _Idx>
2942 __make_from_tuple_impl(_Tuple&& __t, index_sequence<_Idx...>)
2943 { return _Tp(std::get<_Idx>(std::forward<_Tuple>(__t))...); }
2945#if __cpp_lib_tuple_like // >= C++23
2946 template <typename _Tp, __tuple_like _Tuple>
2948 template <typename _Tp, typename _Tuple>
2951 make_from_tuple(_Tuple&& __t)
2952 noexcept(__unpack_std_tuple<is_nothrow_constructible, _Tp, _Tuple>)
2954 constexpr size_t __n = tuple_size_v<remove_reference_t<_Tuple>>;
2955#if __has_builtin(__reference_constructs_from_temporary)
2956 if constexpr (__n == 1)
2958 using _Elt = decltype(std::get<0>(std::declval<_Tuple>()));
2959 static_assert(!__reference_constructs_from_temporary(_Tp, _Elt));
2962 return __make_from_tuple_impl<_Tp>(std::forward<_Tuple>(__t),
2963 make_index_sequence<__n>{});
2967#if __cpp_lib_tuple_like // >= C++23
2968 template<__tuple_like _TTuple, __tuple_like _UTuple,
2969 template<typename> class _TQual, template<typename> class _UQual,
2970 typename = make_index_sequence<tuple_size_v<_TTuple>>>
2971 struct __tuple_like_common_reference;
2973 template<__tuple_like _TTuple, __tuple_like _UTuple,
2974 template<typename> class _TQual, template<typename> class _UQual,
2977 { typename tuple<common_reference_t<_TQual<tuple_element_t<_Is, _TTuple>>,
2978 _UQual<tuple_element_t<_Is, _UTuple>>>...>; }
2979 struct __tuple_like_common_reference<_TTuple, _UTuple, _TQual, _UQual, index_sequence<_Is...>>
2981 using type = tuple<common_reference_t<_TQual<tuple_element_t<_Is, _TTuple>>,
2982 _UQual<tuple_element_t<_Is, _UTuple>>>...>;
2985 template<__tuple_like _TTuple, __tuple_like _UTuple,
2986 template<typename> class _TQual, template<typename> class _UQual>
2987 requires (__is_tuple_v<_TTuple> || __is_tuple_v<_UTuple>)
2988 && is_same_v<_TTuple, decay_t<_TTuple>>
2989 && is_same_v<_UTuple, decay_t<_UTuple>>
2990 && (tuple_size_v<_TTuple> == tuple_size_v<_UTuple>)
2991 && requires { typename __tuple_like_common_reference<_TTuple, _UTuple, _TQual, _UQual>::type; }
2992 struct basic_common_reference<_TTuple, _UTuple, _TQual, _UQual>
2994 using type = typename __tuple_like_common_reference<_TTuple, _UTuple, _TQual, _UQual>::type;
2997 template<__tuple_like _TTuple, __tuple_like _UTuple,
2998 typename = make_index_sequence<tuple_size_v<_TTuple>>>
2999 struct __tuple_like_common_type;
3001 template<__tuple_like _TTuple, __tuple_like _UTuple, size_t... _Is>
3003 { typename tuple<common_type_t<tuple_element_t<_Is, _TTuple>,
3004 tuple_element_t<_Is, _UTuple>>...>; }
3005 struct __tuple_like_common_type<_TTuple, _UTuple, index_sequence<_Is...>>
3007 using type = tuple<common_type_t<tuple_element_t<_Is, _TTuple>,
3008 tuple_element_t<_Is, _UTuple>>...>;
3011 template<__tuple_like _TTuple, __tuple_like _UTuple>
3012 requires (__is_tuple_v<_TTuple> || __is_tuple_v<_UTuple>)
3013 && is_same_v<_TTuple, decay_t<_TTuple>>
3014 && is_same_v<_UTuple, decay_t<_UTuple>>
3015 && (tuple_size_v<_TTuple> == tuple_size_v<_UTuple>)
3016 && requires { typename __tuple_like_common_type<_TTuple, _UTuple>::type; }
3017 struct common_type<_TTuple, _UTuple>
3019 using type = typename __tuple_like_common_type<_TTuple, _UTuple>::type;
3025#undef __glibcxx_no_dangling_refs
3027_GLIBCXX_END_NAMESPACE_VERSION
3032#endif // _GLIBCXX_TUPLE