1// <tuple> -*- C++ -*-
2
3// Copyright (C) 2007-2021 Free Software Foundation, Inc.
4//
5// This file is part of the GNU ISO C++ Library. This library is free
6// software; you can redistribute it and/or modify it under the
7// terms of the GNU General Public License as published by the
8// Free Software Foundation; either version 3, or (at your option)
9// any later version.
10
11// This library is distributed in the hope that it will be useful,
12// but WITHOUT ANY WARRANTY; without even the implied warranty of
13// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14// GNU General Public License for more details.
15
16// Under Section 7 of GPL version 3, you are granted additional
17// permissions described in the GCC Runtime Library Exception, version
18// 3.1, as published by the Free Software Foundation.
19
20// You should have received a copy of the GNU General Public License and
21// a copy of the GCC Runtime Library Exception along with this program;
22// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
23// <http://www.gnu.org/licenses/>.
24
25/** @file include/tuple
26 * This is a Standard C++ Library header.
27 */
28
29#ifndef _GLIBCXX_TUPLE
30#define _GLIBCXX_TUPLE 1
31
32#pragma GCC system_header
33
34#if __cplusplus < 201103L
35# include <bits/c++0x_warning.h>
36#else
37
38#include <utility>
39#include <array>
40#include <bits/uses_allocator.h>
41#include <bits/invoke.h>
42#if __cplusplus > 201703L
43# include <compare>
44# define __cpp_lib_constexpr_tuple 201811L
45#endif
46
47namespace std _GLIBCXX_VISIBILITY(default)
48{
49_GLIBCXX_BEGIN_NAMESPACE_VERSION
50
51 /**
52 * @addtogroup utilities
53 * @{
54 */
55
56 template<typename... _Elements>
57 class tuple;
58
59 template<typename _Tp>
60 struct __is_empty_non_tuple : is_empty<_Tp> { };
61
62 // Using EBO for elements that are tuples causes ambiguous base errors.
63 template<typename _El0, typename... _El>
64 struct __is_empty_non_tuple<tuple<_El0, _El...>> : false_type { };
65
66 // Use the Empty Base-class Optimization for empty, non-final types.
67 template<typename _Tp>
68 using __empty_not_final
69 = typename conditional<__is_final(_Tp), false_type,
70 __is_empty_non_tuple<_Tp>>::type;
71
72 template<size_t _Idx, typename _Head,
73 bool = __empty_not_final<_Head>::value>
74 struct _Head_base;
75
76#if __has_cpp_attribute(__no_unique_address__)
77 template<size_t _Idx, typename _Head>
78 struct _Head_base<_Idx, _Head, true>
79 {
80 constexpr _Head_base()
81 : _M_head_impl() { }
82
83 constexpr _Head_base(const _Head& __h)
84 : _M_head_impl(__h) { }
85
86 constexpr _Head_base(const _Head_base&) = default;
87 constexpr _Head_base(_Head_base&&) = default;
88
89 template<typename _UHead>
90 constexpr _Head_base(_UHead&& __h)
91 : _M_head_impl(std::forward<_UHead>(__h)) { }
92
93 _GLIBCXX20_CONSTEXPR
94 _Head_base(allocator_arg_t, __uses_alloc0)
95 : _M_head_impl() { }
96
97 template<typename _Alloc>
98 _GLIBCXX20_CONSTEXPR
99 _Head_base(allocator_arg_t, __uses_alloc1<_Alloc> __a)
100 : _M_head_impl(allocator_arg, *__a._M_a) { }
101
102 template<typename _Alloc>
103 _GLIBCXX20_CONSTEXPR
104 _Head_base(allocator_arg_t, __uses_alloc2<_Alloc> __a)
105 : _M_head_impl(*__a._M_a) { }
106
107 template<typename _UHead>
108 _GLIBCXX20_CONSTEXPR
109 _Head_base(__uses_alloc0, _UHead&& __uhead)
110 : _M_head_impl(std::forward<_UHead>(__uhead)) { }
111
112 template<typename _Alloc, typename _UHead>
113 _GLIBCXX20_CONSTEXPR
114 _Head_base(__uses_alloc1<_Alloc> __a, _UHead&& __uhead)
115 : _M_head_impl(allocator_arg, *__a._M_a, std::forward<_UHead>(__uhead))
116 { }
117
118 template<typename _Alloc, typename _UHead>
119 _GLIBCXX20_CONSTEXPR
120 _Head_base(__uses_alloc2<_Alloc> __a, _UHead&& __uhead)
121 : _M_head_impl(std::forward<_UHead>(__uhead), *__a._M_a) { }
122
123 static constexpr _Head&
124 _M_head(_Head_base& __b) noexcept { return __b._M_head_impl; }
125
126 static constexpr const _Head&
127 _M_head(const _Head_base& __b) noexcept { return __b._M_head_impl; }
128
129 [[__no_unique_address__]] _Head _M_head_impl;
130 };
131#else
132 template<size_t _Idx, typename _Head>
133 struct _Head_base<_Idx, _Head, true>
134 : public _Head
135 {
136 constexpr _Head_base()
137 : _Head() { }
138
139 constexpr _Head_base(const _Head& __h)
140 : _Head(__h) { }
141
142 constexpr _Head_base(const _Head_base&) = default;
143 constexpr _Head_base(_Head_base&&) = default;
144
145 template<typename _UHead>
146 constexpr _Head_base(_UHead&& __h)
147 : _Head(std::forward<_UHead>(__h)) { }
148
149 _GLIBCXX20_CONSTEXPR
150 _Head_base(allocator_arg_t, __uses_alloc0)
151 : _Head() { }
152
153 template<typename _Alloc>
154 _GLIBCXX20_CONSTEXPR
155 _Head_base(allocator_arg_t, __uses_alloc1<_Alloc> __a)
156 : _Head(allocator_arg, *__a._M_a) { }
157
158 template<typename _Alloc>
159 _GLIBCXX20_CONSTEXPR
160 _Head_base(allocator_arg_t, __uses_alloc2<_Alloc> __a)
161 : _Head(*__a._M_a) { }
162
163 template<typename _UHead>
164 _GLIBCXX20_CONSTEXPR
165 _Head_base(__uses_alloc0, _UHead&& __uhead)
166 : _Head(std::forward<_UHead>(__uhead)) { }
167
168 template<typename _Alloc, typename _UHead>
169 _GLIBCXX20_CONSTEXPR
170 _Head_base(__uses_alloc1<_Alloc> __a, _UHead&& __uhead)
171 : _Head(allocator_arg, *__a._M_a, std::forward<_UHead>(__uhead)) { }
172
173 template<typename _Alloc, typename _UHead>
174 _GLIBCXX20_CONSTEXPR
175 _Head_base(__uses_alloc2<_Alloc> __a, _UHead&& __uhead)
176 : _Head(std::forward<_UHead>(__uhead), *__a._M_a) { }
177
178 static constexpr _Head&
179 _M_head(_Head_base& __b) noexcept { return __b; }
180
181 static constexpr const _Head&
182 _M_head(const _Head_base& __b) noexcept { return __b; }
183 };
184#endif
185
186 template<size_t _Idx, typename _Head>
187 struct _Head_base<_Idx, _Head, false>
188 {
189 constexpr _Head_base()
190 : _M_head_impl() { }
191
192 constexpr _Head_base(const _Head& __h)
193 : _M_head_impl(__h) { }
194
195 constexpr _Head_base(const _Head_base&) = default;
196 constexpr _Head_base(_Head_base&&) = default;
197
198 template<typename _UHead>
199 constexpr _Head_base(_UHead&& __h)
200 : _M_head_impl(std::forward<_UHead>(__h)) { }
201
202 _GLIBCXX20_CONSTEXPR
203 _Head_base(allocator_arg_t, __uses_alloc0)
204 : _M_head_impl() { }
205
206 template<typename _Alloc>
207 _GLIBCXX20_CONSTEXPR
208 _Head_base(allocator_arg_t, __uses_alloc1<_Alloc> __a)
209 : _M_head_impl(allocator_arg, *__a._M_a) { }
210
211 template<typename _Alloc>
212 _GLIBCXX20_CONSTEXPR
213 _Head_base(allocator_arg_t, __uses_alloc2<_Alloc> __a)
214 : _M_head_impl(*__a._M_a) { }
215
216 template<typename _UHead>
217 _GLIBCXX20_CONSTEXPR
218 _Head_base(__uses_alloc0, _UHead&& __uhead)
219 : _M_head_impl(std::forward<_UHead>(__uhead)) { }
220
221 template<typename _Alloc, typename _UHead>
222 _GLIBCXX20_CONSTEXPR
223 _Head_base(__uses_alloc1<_Alloc> __a, _UHead&& __uhead)
224 : _M_head_impl(allocator_arg, *__a._M_a, std::forward<_UHead>(__uhead))
225 { }
226
227 template<typename _Alloc, typename _UHead>
228 _GLIBCXX20_CONSTEXPR
229 _Head_base(__uses_alloc2<_Alloc> __a, _UHead&& __uhead)
230 : _M_head_impl(std::forward<_UHead>(__uhead), *__a._M_a) { }
231
232 static constexpr _Head&
233 _M_head(_Head_base& __b) noexcept { return __b._M_head_impl; }
234
235 static constexpr const _Head&
236 _M_head(const _Head_base& __b) noexcept { return __b._M_head_impl; }
237
238 _Head _M_head_impl;
239 };
240
241 /**
242 * Contains the actual implementation of the @c tuple template, stored
243 * as a recursive inheritance hierarchy from the first element (most
244 * derived class) to the last (least derived class). The @c Idx
245 * parameter gives the 0-based index of the element stored at this
246 * point in the hierarchy; we use it to implement a constant-time
247 * get() operation.
248 */
249 template<size_t _Idx, typename... _Elements>
250 struct _Tuple_impl;
251
252 /**
253 * Recursive tuple implementation. Here we store the @c Head element
254 * and derive from a @c Tuple_impl containing the remaining elements
255 * (which contains the @c Tail).
256 */
257 template<size_t _Idx, typename _Head, typename... _Tail>
258 struct _Tuple_impl<_Idx, _Head, _Tail...>
259 : public _Tuple_impl<_Idx + 1, _Tail...>,
260 private _Head_base<_Idx, _Head>
261 {
262 template<size_t, typename...> friend struct _Tuple_impl;
263
264 typedef _Tuple_impl<_Idx + 1, _Tail...> _Inherited;
265 typedef _Head_base<_Idx, _Head> _Base;
266
267 static constexpr _Head&
268 _M_head(_Tuple_impl& __t) noexcept { return _Base::_M_head(__t); }
269
270 static constexpr const _Head&
271 _M_head(const _Tuple_impl& __t) noexcept { return _Base::_M_head(__t); }
272
273 static constexpr _Inherited&
274 _M_tail(_Tuple_impl& __t) noexcept { return __t; }
275
276 static constexpr const _Inherited&
277 _M_tail(const _Tuple_impl& __t) noexcept { return __t; }
278
279 constexpr _Tuple_impl()
280 : _Inherited(), _Base() { }
281
282 explicit constexpr
283 _Tuple_impl(const _Head& __head, const _Tail&... __tail)
284 : _Inherited(__tail...), _Base(__head)
285 { }
286
287 template<typename _UHead, typename... _UTail,
288 typename = __enable_if_t<sizeof...(_Tail) == sizeof...(_UTail)>>
289 explicit constexpr
290 _Tuple_impl(_UHead&& __head, _UTail&&... __tail)
291 : _Inherited(std::forward<_UTail>(__tail)...),
292 _Base(std::forward<_UHead>(__head))
293 { }
294
295 constexpr _Tuple_impl(const _Tuple_impl&) = default;
296
297 // _GLIBCXX_RESOLVE_LIB_DEFECTS
298 // 2729. Missing SFINAE on std::pair::operator=
299 _Tuple_impl& operator=(const _Tuple_impl&) = delete;
300
301 _Tuple_impl(_Tuple_impl&&) = default;
302
303 template<typename... _UElements>
304 constexpr
305 _Tuple_impl(const _Tuple_impl<_Idx, _UElements...>& __in)
306 : _Inherited(_Tuple_impl<_Idx, _UElements...>::_M_tail(__in)),
307 _Base(_Tuple_impl<_Idx, _UElements...>::_M_head(__in))
308 { }
309
310 template<typename _UHead, typename... _UTails>
311 constexpr
312 _Tuple_impl(_Tuple_impl<_Idx, _UHead, _UTails...>&& __in)
313 : _Inherited(std::move
314 (_Tuple_impl<_Idx, _UHead, _UTails...>::_M_tail(__in))),
315 _Base(std::forward<_UHead>
316 (_Tuple_impl<_Idx, _UHead, _UTails...>::_M_head(__in)))
317 { }
318
319 template<typename _Alloc>
320 _GLIBCXX20_CONSTEXPR
321 _Tuple_impl(allocator_arg_t __tag, const _Alloc& __a)
322 : _Inherited(__tag, __a),
323 _Base(__tag, __use_alloc<_Head>(__a))
324 { }
325
326 template<typename _Alloc>
327 _GLIBCXX20_CONSTEXPR
328 _Tuple_impl(allocator_arg_t __tag, const _Alloc& __a,
329 const _Head& __head, const _Tail&... __tail)
330 : _Inherited(__tag, __a, __tail...),
331 _Base(__use_alloc<_Head, _Alloc, _Head>(__a), __head)
332 { }
333
334 template<typename _Alloc, typename _UHead, typename... _UTail,
335 typename = __enable_if_t<sizeof...(_Tail) == sizeof...(_UTail)>>
336 _GLIBCXX20_CONSTEXPR
337 _Tuple_impl(allocator_arg_t __tag, const _Alloc& __a,
338 _UHead&& __head, _UTail&&... __tail)
339 : _Inherited(__tag, __a, std::forward<_UTail>(__tail)...),
340 _Base(__use_alloc<_Head, _Alloc, _UHead>(__a),
341 std::forward<_UHead>(__head))
342 { }
343
344 template<typename _Alloc>
345 _GLIBCXX20_CONSTEXPR
346 _Tuple_impl(allocator_arg_t __tag, const _Alloc& __a,
347 const _Tuple_impl& __in)
348 : _Inherited(__tag, __a, _M_tail(__in)),
349 _Base(__use_alloc<_Head, _Alloc, _Head>(__a), _M_head(__in))
350 { }
351
352 template<typename _Alloc>
353 _GLIBCXX20_CONSTEXPR
354 _Tuple_impl(allocator_arg_t __tag, const _Alloc& __a,
355 _Tuple_impl&& __in)
356 : _Inherited(__tag, __a, std::move(_M_tail(__in))),
357 _Base(__use_alloc<_Head, _Alloc, _Head>(__a),
358 std::forward<_Head>(_M_head(__in)))
359 { }
360
361 template<typename _Alloc, typename _UHead, typename... _UTails>
362 _GLIBCXX20_CONSTEXPR
363 _Tuple_impl(allocator_arg_t __tag, const _Alloc& __a,
364 const _Tuple_impl<_Idx, _UHead, _UTails...>& __in)
365 : _Inherited(__tag, __a,
366 _Tuple_impl<_Idx, _UHead, _UTails...>::_M_tail(__in)),
367 _Base(__use_alloc<_Head, _Alloc, const _UHead&>(__a),
368 _Tuple_impl<_Idx, _UHead, _UTails...>::_M_head(__in))
369 { }
370
371 template<typename _Alloc, typename _UHead, typename... _UTails>
372 _GLIBCXX20_CONSTEXPR
373 _Tuple_impl(allocator_arg_t __tag, const _Alloc& __a,
374 _Tuple_impl<_Idx, _UHead, _UTails...>&& __in)
375 : _Inherited(__tag, __a, std::move
376 (_Tuple_impl<_Idx, _UHead, _UTails...>::_M_tail(__in))),
377 _Base(__use_alloc<_Head, _Alloc, _UHead>(__a),
378 std::forward<_UHead>
379 (_Tuple_impl<_Idx, _UHead, _UTails...>::_M_head(__in)))
380 { }
381
382 template<typename... _UElements>
383 _GLIBCXX20_CONSTEXPR
384 void
385 _M_assign(const _Tuple_impl<_Idx, _UElements...>& __in)
386 {
387 _M_head(*this) = _Tuple_impl<_Idx, _UElements...>::_M_head(__in);
388 _M_tail(*this)._M_assign(
389 _Tuple_impl<_Idx, _UElements...>::_M_tail(__in));
390 }
391
392 template<typename _UHead, typename... _UTails>
393 _GLIBCXX20_CONSTEXPR
394 void
395 _M_assign(_Tuple_impl<_Idx, _UHead, _UTails...>&& __in)
396 {
397 _M_head(*this) = std::forward<_UHead>
398 (_Tuple_impl<_Idx, _UHead, _UTails...>::_M_head(__in));
399 _M_tail(*this)._M_assign(
400 std::move(_Tuple_impl<_Idx, _UHead, _UTails...>::_M_tail(__in)));
401 }
402
403 protected:
404 _GLIBCXX20_CONSTEXPR
405 void
406 _M_swap(_Tuple_impl& __in)
407 {
408 using std::swap;
409 swap(_M_head(*this), _M_head(__in));
410 _Inherited::_M_swap(_M_tail(__in));
411 }
412 };
413
414 // Basis case of inheritance recursion.
415 template<size_t _Idx, typename _Head>
416 struct _Tuple_impl<_Idx, _Head>
417 : private _Head_base<_Idx, _Head>
418 {
419 template<size_t, typename...> friend struct _Tuple_impl;
420
421 typedef _Head_base<_Idx, _Head> _Base;
422
423 static constexpr _Head&
424 _M_head(_Tuple_impl& __t) noexcept { return _Base::_M_head(__t); }
425
426 static constexpr const _Head&
427 _M_head(const _Tuple_impl& __t) noexcept { return _Base::_M_head(__t); }
428
429 constexpr
430 _Tuple_impl()
431 : _Base() { }
432
433 explicit constexpr
434 _Tuple_impl(const _Head& __head)
435 : _Base(__head)
436 { }
437
438 template<typename _UHead>
439 explicit constexpr
440 _Tuple_impl(_UHead&& __head)
441 : _Base(std::forward<_UHead>(__head))
442 { }
443
444 constexpr _Tuple_impl(const _Tuple_impl&) = default;
445
446 // _GLIBCXX_RESOLVE_LIB_DEFECTS
447 // 2729. Missing SFINAE on std::pair::operator=
448 _Tuple_impl& operator=(const _Tuple_impl&) = delete;
449
450#if _GLIBCXX_INLINE_VERSION
451 _Tuple_impl(_Tuple_impl&&) = default;
452#else
453 constexpr
454 _Tuple_impl(_Tuple_impl&& __in)
455 noexcept(is_nothrow_move_constructible<_Head>::value)
456 : _Base(static_cast<_Base&&>(__in))
457 { }
458#endif
459
460 template<typename _UHead>
461 constexpr
462 _Tuple_impl(const _Tuple_impl<_Idx, _UHead>& __in)
463 : _Base(_Tuple_impl<_Idx, _UHead>::_M_head(__in))
464 { }
465
466 template<typename _UHead>
467 constexpr
468 _Tuple_impl(_Tuple_impl<_Idx, _UHead>&& __in)
469 : _Base(std::forward<_UHead>(_Tuple_impl<_Idx, _UHead>::_M_head(__in)))
470 { }
471
472 template<typename _Alloc>
473 _GLIBCXX20_CONSTEXPR
474 _Tuple_impl(allocator_arg_t __tag, const _Alloc& __a)
475 : _Base(__tag, __use_alloc<_Head>(__a))
476 { }
477
478 template<typename _Alloc>
479 _GLIBCXX20_CONSTEXPR
480 _Tuple_impl(allocator_arg_t __tag, const _Alloc& __a,
481 const _Head& __head)
482 : _Base(__use_alloc<_Head, _Alloc, const _Head&>(__a), __head)
483 { }
484
485 template<typename _Alloc, typename _UHead>
486 _GLIBCXX20_CONSTEXPR
487 _Tuple_impl(allocator_arg_t __tag, const _Alloc& __a,
488 _UHead&& __head)
489 : _Base(__use_alloc<_Head, _Alloc, _UHead>(__a),
490 std::forward<_UHead>(__head))
491 { }
492
493 template<typename _Alloc>
494 _GLIBCXX20_CONSTEXPR
495 _Tuple_impl(allocator_arg_t __tag, const _Alloc& __a,
496 const _Tuple_impl& __in)
497 : _Base(__use_alloc<_Head, _Alloc, const _Head&>(__a), _M_head(__in))
498 { }
499
500 template<typename _Alloc>
501 _GLIBCXX20_CONSTEXPR
502 _Tuple_impl(allocator_arg_t __tag, const _Alloc& __a,
503 _Tuple_impl&& __in)
504 : _Base(__use_alloc<_Head, _Alloc, _Head>(__a),
505 std::forward<_Head>(_M_head(__in)))
506 { }
507
508 template<typename _Alloc, typename _UHead>
509 _GLIBCXX20_CONSTEXPR
510 _Tuple_impl(allocator_arg_t __tag, const _Alloc& __a,
511 const _Tuple_impl<_Idx, _UHead>& __in)
512 : _Base(__use_alloc<_Head, _Alloc, const _UHead&>(__a),
513 _Tuple_impl<_Idx, _UHead>::_M_head(__in))
514 { }
515
516 template<typename _Alloc, typename _UHead>
517 _GLIBCXX20_CONSTEXPR
518 _Tuple_impl(allocator_arg_t __tag, const _Alloc& __a,
519 _Tuple_impl<_Idx, _UHead>&& __in)
520 : _Base(__use_alloc<_Head, _Alloc, _UHead>(__a),
521 std::forward<_UHead>(_Tuple_impl<_Idx, _UHead>::_M_head(__in)))
522 { }
523
524 template<typename _UHead>
525 _GLIBCXX20_CONSTEXPR
526 void
527 _M_assign(const _Tuple_impl<_Idx, _UHead>& __in)
528 {
529 _M_head(*this) = _Tuple_impl<_Idx, _UHead>::_M_head(__in);
530 }
531
532 template<typename _UHead>
533 _GLIBCXX20_CONSTEXPR
534 void
535 _M_assign(_Tuple_impl<_Idx, _UHead>&& __in)
536 {
537 _M_head(*this)
538 = std::forward<_UHead>(_Tuple_impl<_Idx, _UHead>::_M_head(__in));
539 }
540
541 protected:
542 _GLIBCXX20_CONSTEXPR
543 void
544 _M_swap(_Tuple_impl& __in)
545 {
546 using std::swap;
547 swap(_M_head(*this), _M_head(__in));
548 }
549 };
550
551 // Concept utility functions, reused in conditionally-explicit
552 // constructors.
553 template<bool, typename... _Types>
554 struct _TupleConstraints
555 {
556 // Constraint for a non-explicit constructor.
557 // True iff each Ti in _Types... can be constructed from Ui in _UTypes...
558 // and every Ui is implicitly convertible to Ti.
559 template<typename... _UTypes>
560 static constexpr bool __is_implicitly_constructible()
561 {
562 return __and_<is_constructible<_Types, _UTypes>...,
563 is_convertible<_UTypes, _Types>...
564 >::value;
565 }
566
567 // Constraint for a non-explicit constructor.
568 // True iff each Ti in _Types... can be constructed from Ui in _UTypes...
569 // but not every Ui is implicitly convertible to Ti.
570 template<typename... _UTypes>
571 static constexpr bool __is_explicitly_constructible()
572 {
573 return __and_<is_constructible<_Types, _UTypes>...,
574 __not_<__and_<is_convertible<_UTypes, _Types>...>>
575 >::value;
576 }
577
578 static constexpr bool __is_implicitly_default_constructible()
579 {
580 return __and_<std::__is_implicitly_default_constructible<_Types>...
581 >::value;
582 }
583
584 static constexpr bool __is_explicitly_default_constructible()
585 {
586 return __and_<is_default_constructible<_Types>...,
587 __not_<__and_<
588 std::__is_implicitly_default_constructible<_Types>...>
589 >>::value;
590 }
591 };
592
593 // Partial specialization used when a required precondition isn't met,
594 // e.g. when sizeof...(_Types) != sizeof...(_UTypes).
595 template<typename... _Types>
596 struct _TupleConstraints<false, _Types...>
597 {
598 template<typename... _UTypes>
599 static constexpr bool __is_implicitly_constructible()
600 { return false; }
601
602 template<typename... _UTypes>
603 static constexpr bool __is_explicitly_constructible()
604 { return false; }
605 };
606
607 /// Primary class template, tuple
608 template<typename... _Elements>
609 class tuple : public _Tuple_impl<0, _Elements...>
610 {
611 typedef _Tuple_impl<0, _Elements...> _Inherited;
612
613 template<bool _Cond>
614 using _TCC = _TupleConstraints<_Cond, _Elements...>;
615
616 // Constraint for non-explicit default constructor
617 template<bool _Dummy>
618 using _ImplicitDefaultCtor = __enable_if_t<
619 _TCC<_Dummy>::__is_implicitly_default_constructible(),
620 bool>;
621
622 // Constraint for explicit default constructor
623 template<bool _Dummy>
624 using _ExplicitDefaultCtor = __enable_if_t<
625 _TCC<_Dummy>::__is_explicitly_default_constructible(),
626 bool>;
627
628 // Constraint for non-explicit constructors
629 template<bool _Cond, typename... _Args>
630 using _ImplicitCtor = __enable_if_t<
631 _TCC<_Cond>::template __is_implicitly_constructible<_Args...>(),
632 bool>;
633
634 // Constraint for non-explicit constructors
635 template<bool _Cond, typename... _Args>
636 using _ExplicitCtor = __enable_if_t<
637 _TCC<_Cond>::template __is_explicitly_constructible<_Args...>(),
638 bool>;
639
640 template<typename... _UElements>
641 static constexpr
642 __enable_if_t<sizeof...(_UElements) == sizeof...(_Elements), bool>
643 __assignable()
644 { return __and_<is_assignable<_Elements&, _UElements>...>::value; }
645
646 // Condition for noexcept-specifier of an assignment operator.
647 template<typename... _UElements>
648 static constexpr bool __nothrow_assignable()
649 {
650 return
651 __and_<is_nothrow_assignable<_Elements&, _UElements>...>::value;
652 }
653
654 // Condition for noexcept-specifier of a constructor.
655 template<typename... _UElements>
656 static constexpr bool __nothrow_constructible()
657 {
658 return
659 __and_<is_nothrow_constructible<_Elements, _UElements>...>::value;
660 }
661
662 // Constraint for tuple(_UTypes&&...) where sizeof...(_UTypes) == 1.
663 template<typename _Up>
664 static constexpr bool __valid_args()
665 {
666 return sizeof...(_Elements) == 1
667 && !is_same<tuple, __remove_cvref_t<_Up>>::value;
668 }
669
670 // Constraint for tuple(_UTypes&&...) where sizeof...(_UTypes) > 1.
671 template<typename, typename, typename... _Tail>
672 static constexpr bool __valid_args()
673 { return (sizeof...(_Tail) + 2) == sizeof...(_Elements); }
674
675 /* Constraint for constructors with a tuple<UTypes...> parameter ensures
676 * that the constructor is only viable when it would not interfere with
677 * tuple(UTypes&&...) or tuple(const tuple&) or tuple(tuple&&).
678 * Such constructors are only viable if:
679 * either sizeof...(Types) != 1,
680 * or (when Types... expands to T and UTypes... expands to U)
681 * is_convertible_v<TUPLE, T>, is_constructible_v<T, TUPLE>,
682 * and is_same_v<T, U> are all false.
683 */
684 template<typename _Tuple, typename = tuple,
685 typename = __remove_cvref_t<_Tuple>>
686 struct _UseOtherCtor
687 : false_type
688 { };
689 // If TUPLE is convertible to the single element in *this,
690 // then TUPLE should match tuple(UTypes&&...) instead.
691 template<typename _Tuple, typename _Tp, typename _Up>
692 struct _UseOtherCtor<_Tuple, tuple<_Tp>, tuple<_Up>>
693 : __or_<is_convertible<_Tuple, _Tp>, is_constructible<_Tp, _Tuple>>
694 { };
695 // If TUPLE and *this each have a single element of the same type,
696 // then TUPLE should match a copy/move constructor instead.
697 template<typename _Tuple, typename _Tp>
698 struct _UseOtherCtor<_Tuple, tuple<_Tp>, tuple<_Tp>>
699 : true_type
700 { };
701
702 // Return true iff sizeof...(Types) == 1 && tuple_size_v<TUPLE> == 1
703 // and the single element in Types can be initialized from TUPLE,
704 // or is the same type as tuple_element_t<0, TUPLE>.
705 template<typename _Tuple>
706 static constexpr bool __use_other_ctor()
707 { return _UseOtherCtor<_Tuple>::value; }
708
709 public:
710 template<typename _Dummy = void,
711 _ImplicitDefaultCtor<is_void<_Dummy>::value> = true>
712 constexpr
713 tuple()
714 noexcept(__and_<is_nothrow_default_constructible<_Elements>...>::value)
715 : _Inherited() { }
716
717 template<typename _Dummy = void,
718 _ExplicitDefaultCtor<is_void<_Dummy>::value> = false>
719 explicit constexpr
720 tuple()
721 noexcept(__and_<is_nothrow_default_constructible<_Elements>...>::value)
722 : _Inherited() { }
723
724 template<bool _NotEmpty = (sizeof...(_Elements) >= 1),
725 _ImplicitCtor<_NotEmpty, const _Elements&...> = true>
726 constexpr
727 tuple(const _Elements&... __elements)
728 noexcept(__nothrow_constructible<const _Elements&...>())
729 : _Inherited(__elements...) { }
730
731 template<bool _NotEmpty = (sizeof...(_Elements) >= 1),
732 _ExplicitCtor<_NotEmpty, const _Elements&...> = false>
733 explicit constexpr
734 tuple(const _Elements&... __elements)
735 noexcept(__nothrow_constructible<const _Elements&...>())
736 : _Inherited(__elements...) { }
737
738 template<typename... _UElements,
739 bool _Valid = __valid_args<_UElements...>(),
740 _ImplicitCtor<_Valid, _UElements...> = true>
741 constexpr
742 tuple(_UElements&&... __elements)
743 noexcept(__nothrow_constructible<_UElements...>())
744 : _Inherited(std::forward<_UElements>(__elements)...) { }
745
746 template<typename... _UElements,
747 bool _Valid = __valid_args<_UElements...>(),
748 _ExplicitCtor<_Valid, _UElements...> = false>
749 explicit constexpr
750 tuple(_UElements&&... __elements)
751 noexcept(__nothrow_constructible<_UElements...>())
752 : _Inherited(std::forward<_UElements>(__elements)...) { }
753
754 constexpr tuple(const tuple&) = default;
755
756 constexpr tuple(tuple&&) = default;
757
758 template<typename... _UElements,
759 bool _Valid = (sizeof...(_Elements) == sizeof...(_UElements))
760 && !__use_other_ctor<const tuple<_UElements...>&>(),
761 _ImplicitCtor<_Valid, const _UElements&...> = true>
762 constexpr
763 tuple(const tuple<_UElements...>& __in)
764 noexcept(__nothrow_constructible<const _UElements&...>())
765 : _Inherited(static_cast<const _Tuple_impl<0, _UElements...>&>(__in))
766 { }
767
768 template<typename... _UElements,
769 bool _Valid = (sizeof...(_Elements) == sizeof...(_UElements))
770 && !__use_other_ctor<const tuple<_UElements...>&>(),
771 _ExplicitCtor<_Valid, const _UElements&...> = false>
772 explicit constexpr
773 tuple(const tuple<_UElements...>& __in)
774 noexcept(__nothrow_constructible<const _UElements&...>())
775 : _Inherited(static_cast<const _Tuple_impl<0, _UElements...>&>(__in))
776 { }
777
778 template<typename... _UElements,
779 bool _Valid = (sizeof...(_Elements) == sizeof...(_UElements))
780 && !__use_other_ctor<tuple<_UElements...>&&>(),
781 _ImplicitCtor<_Valid, _UElements...> = true>
782 constexpr
783 tuple(tuple<_UElements...>&& __in)
784 noexcept(__nothrow_constructible<_UElements...>())
785 : _Inherited(static_cast<_Tuple_impl<0, _UElements...>&&>(__in)) { }
786
787 template<typename... _UElements,
788 bool _Valid = (sizeof...(_Elements) == sizeof...(_UElements))
789 && !__use_other_ctor<tuple<_UElements...>&&>(),
790 _ExplicitCtor<_Valid, _UElements...> = false>
791 explicit constexpr
792 tuple(tuple<_UElements...>&& __in)
793 noexcept(__nothrow_constructible<_UElements...>())
794 : _Inherited(static_cast<_Tuple_impl<0, _UElements...>&&>(__in)) { }
795
796 // Allocator-extended constructors.
797
798 template<typename _Alloc,
799 _ImplicitDefaultCtor<is_object<_Alloc>::value> = true>
800 _GLIBCXX20_CONSTEXPR
801 tuple(allocator_arg_t __tag, const _Alloc& __a)
802 : _Inherited(__tag, __a) { }
803
804 template<typename _Alloc, bool _NotEmpty = (sizeof...(_Elements) >= 1),
805 _ImplicitCtor<_NotEmpty, const _Elements&...> = true>
806 _GLIBCXX20_CONSTEXPR
807 tuple(allocator_arg_t __tag, const _Alloc& __a,
808 const _Elements&... __elements)
809 : _Inherited(__tag, __a, __elements...) { }
810
811 template<typename _Alloc, bool _NotEmpty = (sizeof...(_Elements) >= 1),
812 _ExplicitCtor<_NotEmpty, const _Elements&...> = false>
813 _GLIBCXX20_CONSTEXPR
814 explicit
815 tuple(allocator_arg_t __tag, const _Alloc& __a,
816 const _Elements&... __elements)
817 : _Inherited(__tag, __a, __elements...) { }
818
819 template<typename _Alloc, typename... _UElements,
820 bool _Valid = __valid_args<_UElements...>(),
821 _ImplicitCtor<_Valid, _UElements...> = true>
822 _GLIBCXX20_CONSTEXPR
823 tuple(allocator_arg_t __tag, const _Alloc& __a,
824 _UElements&&... __elements)
825 : _Inherited(__tag, __a, std::forward<_UElements>(__elements)...)
826 { }
827
828 template<typename _Alloc, typename... _UElements,
829 bool _Valid = __valid_args<_UElements...>(),
830 _ExplicitCtor<_Valid, _UElements...> = false>
831 _GLIBCXX20_CONSTEXPR
832 explicit
833 tuple(allocator_arg_t __tag, const _Alloc& __a,
834 _UElements&&... __elements)
835 : _Inherited(__tag, __a, std::forward<_UElements>(__elements)...)
836 { }
837
838 template<typename _Alloc>
839 _GLIBCXX20_CONSTEXPR
840 tuple(allocator_arg_t __tag, const _Alloc& __a, const tuple& __in)
841 : _Inherited(__tag, __a, static_cast<const _Inherited&>(__in)) { }
842
843 template<typename _Alloc>
844 _GLIBCXX20_CONSTEXPR
845 tuple(allocator_arg_t __tag, const _Alloc& __a, tuple&& __in)
846 : _Inherited(__tag, __a, static_cast<_Inherited&&>(__in)) { }
847
848 template<typename _Alloc, typename... _UElements,
849 bool _Valid = (sizeof...(_Elements) == sizeof...(_UElements))
850 && !__use_other_ctor<const tuple<_UElements...>&>(),
851 _ImplicitCtor<_Valid, const _UElements&...> = true>
852 _GLIBCXX20_CONSTEXPR
853 tuple(allocator_arg_t __tag, const _Alloc& __a,
854 const tuple<_UElements...>& __in)
855 : _Inherited(__tag, __a,
856 static_cast<const _Tuple_impl<0, _UElements...>&>(__in))
857 { }
858
859 template<typename _Alloc, typename... _UElements,
860 bool _Valid = (sizeof...(_Elements) == sizeof...(_UElements))
861 && !__use_other_ctor<const tuple<_UElements...>&>(),
862 _ExplicitCtor<_Valid, const _UElements&...> = false>
863 _GLIBCXX20_CONSTEXPR
864 explicit
865 tuple(allocator_arg_t __tag, const _Alloc& __a,
866 const tuple<_UElements...>& __in)
867 : _Inherited(__tag, __a,
868 static_cast<const _Tuple_impl<0, _UElements...>&>(__in))
869 { }
870
871 template<typename _Alloc, typename... _UElements,
872 bool _Valid = (sizeof...(_Elements) == sizeof...(_UElements))
873 && !__use_other_ctor<tuple<_UElements...>&&>(),
874 _ImplicitCtor<_Valid, _UElements...> = true>
875 _GLIBCXX20_CONSTEXPR
876 tuple(allocator_arg_t __tag, const _Alloc& __a,
877 tuple<_UElements...>&& __in)
878 : _Inherited(__tag, __a,
879 static_cast<_Tuple_impl<0, _UElements...>&&>(__in))
880 { }
881
882 template<typename _Alloc, typename... _UElements,
883 bool _Valid = (sizeof...(_Elements) == sizeof...(_UElements))
884 && !__use_other_ctor<tuple<_UElements...>&&>(),
885 _ExplicitCtor<_Valid, _UElements...> = false>
886 _GLIBCXX20_CONSTEXPR
887 explicit
888 tuple(allocator_arg_t __tag, const _Alloc& __a,
889 tuple<_UElements...>&& __in)
890 : _Inherited(__tag, __a,
891 static_cast<_Tuple_impl<0, _UElements...>&&>(__in))
892 { }
893
894 // tuple assignment
895
896 _GLIBCXX20_CONSTEXPR
897 tuple&
898 operator=(typename conditional<__assignable<const _Elements&...>(),
899 const tuple&,
900 const __nonesuch&>::type __in)
901 noexcept(__nothrow_assignable<const _Elements&...>())
902 {
903 this->_M_assign(__in);
904 return *this;
905 }
906
907 _GLIBCXX20_CONSTEXPR
908 tuple&
909 operator=(typename conditional<__assignable<_Elements...>(),
910 tuple&&,
911 __nonesuch&&>::type __in)
912 noexcept(__nothrow_assignable<_Elements...>())
913 {
914 this->_M_assign(std::move(__in));
915 return *this;
916 }
917
918 template<typename... _UElements>
919 _GLIBCXX20_CONSTEXPR
920 __enable_if_t<__assignable<const _UElements&...>(), tuple&>
921 operator=(const tuple<_UElements...>& __in)
922 noexcept(__nothrow_assignable<const _UElements&...>())
923 {
924 this->_M_assign(__in);
925 return *this;
926 }
927
928 template<typename... _UElements>
929 _GLIBCXX20_CONSTEXPR
930 __enable_if_t<__assignable<_UElements...>(), tuple&>
931 operator=(tuple<_UElements...>&& __in)
932 noexcept(__nothrow_assignable<_UElements...>())
933 {
934 this->_M_assign(std::move(__in));
935 return *this;
936 }
937
938 // tuple swap
939 _GLIBCXX20_CONSTEXPR
940 void
941 swap(tuple& __in)
942 noexcept(__and_<__is_nothrow_swappable<_Elements>...>::value)
943 { _Inherited::_M_swap(__in); }
944 };
945
946#if __cpp_deduction_guides >= 201606
947 template<typename... _UTypes>
948 tuple(_UTypes...) -> tuple<_UTypes...>;
949 template<typename _T1, typename _T2>
950 tuple(pair<_T1, _T2>) -> tuple<_T1, _T2>;
951 template<typename _Alloc, typename... _UTypes>
952 tuple(allocator_arg_t, _Alloc, _UTypes...) -> tuple<_UTypes...>;
953 template<typename _Alloc, typename _T1, typename _T2>
954 tuple(allocator_arg_t, _Alloc, pair<_T1, _T2>) -> tuple<_T1, _T2>;
955 template<typename _Alloc, typename... _UTypes>
956 tuple(allocator_arg_t, _Alloc, tuple<_UTypes...>) -> tuple<_UTypes...>;
957#endif
958
959 // Explicit specialization, zero-element tuple.
960 template<>
961 class tuple<>
962 {
963 public:
964 _GLIBCXX20_CONSTEXPR
965 void swap(tuple&) noexcept { /* no-op */ }
966 // We need the default since we're going to define no-op
967 // allocator constructors.
968 tuple() = default;
969 // No-op allocator constructors.
970 template<typename _Alloc>
971 _GLIBCXX20_CONSTEXPR
972 tuple(allocator_arg_t, const _Alloc&) noexcept { }
973 template<typename _Alloc>
974 _GLIBCXX20_CONSTEXPR
975 tuple(allocator_arg_t, const _Alloc&, const tuple&) noexcept { }
976 };
977
978 /// Partial specialization, 2-element tuple.
979 /// Includes construction and assignment from a pair.
980 template<typename _T1, typename _T2>
981 class tuple<_T1, _T2> : public _Tuple_impl<0, _T1, _T2>
982 {
983 typedef _Tuple_impl<0, _T1, _T2> _Inherited;
984
985 // Constraint for non-explicit default constructor
986 template<bool _Dummy, typename _U1, typename _U2>
987 using _ImplicitDefaultCtor = __enable_if_t<
988 _TupleConstraints<_Dummy, _U1, _U2>::
989 __is_implicitly_default_constructible(),
990 bool>;
991
992 // Constraint for explicit default constructor
993 template<bool _Dummy, typename _U1, typename _U2>
994 using _ExplicitDefaultCtor = __enable_if_t<
995 _TupleConstraints<_Dummy, _U1, _U2>::
996 __is_explicitly_default_constructible(),
997 bool>;
998
999 template<bool _Dummy>
1000 using _TCC = _TupleConstraints<_Dummy, _T1, _T2>;
1001
1002 // Constraint for non-explicit constructors
1003 template<bool _Cond, typename _U1, typename _U2>
1004 using _ImplicitCtor = __enable_if_t<
1005 _TCC<_Cond>::template __is_implicitly_constructible<_U1, _U2>(),
1006 bool>;
1007
1008 // Constraint for non-explicit constructors
1009 template<bool _Cond, typename _U1, typename _U2>
1010 using _ExplicitCtor = __enable_if_t<
1011 _TCC<_Cond>::template __is_explicitly_constructible<_U1, _U2>(),
1012 bool>;
1013
1014 template<typename _U1, typename _U2>
1015 static constexpr bool __assignable()
1016 {
1017 return __and_<is_assignable<_T1&, _U1>,
1018 is_assignable<_T2&, _U2>>::value;
1019 }
1020
1021 template<typename _U1, typename _U2>
1022 static constexpr bool __nothrow_assignable()
1023 {
1024 return __and_<is_nothrow_assignable<_T1&, _U1>,
1025 is_nothrow_assignable<_T2&, _U2>>::value;
1026 }
1027
1028 template<typename _U1, typename _U2>
1029 static constexpr bool __nothrow_constructible()
1030 {
1031 return __and_<is_nothrow_constructible<_T1, _U1>,
1032 is_nothrow_constructible<_T2, _U2>>::value;
1033 }
1034
1035 static constexpr bool __nothrow_default_constructible()
1036 {
1037 return __and_<is_nothrow_default_constructible<_T1>,
1038 is_nothrow_default_constructible<_T2>>::value;
1039 }
1040
1041 template<typename _U1>
1042 static constexpr bool __is_alloc_arg()
1043 { return is_same<__remove_cvref_t<_U1>, allocator_arg_t>::value; }
1044
1045 public:
1046 template<bool _Dummy = true,
1047 _ImplicitDefaultCtor<_Dummy, _T1, _T2> = true>
1048 constexpr
1049 tuple()
1050 noexcept(__nothrow_default_constructible())
1051 : _Inherited() { }
1052
1053 template<bool _Dummy = true,
1054 _ExplicitDefaultCtor<_Dummy, _T1, _T2> = false>
1055 explicit constexpr
1056 tuple()
1057 noexcept(__nothrow_default_constructible())
1058 : _Inherited() { }
1059
1060 template<bool _Dummy = true,
1061 _ImplicitCtor<_Dummy, const _T1&, const _T2&> = true>
1062 constexpr
1063 tuple(const _T1& __a1, const _T2& __a2)
1064 noexcept(__nothrow_constructible<const _T1&, const _T2&>())
1065 : _Inherited(__a1, __a2) { }
1066
1067 template<bool _Dummy = true,
1068 _ExplicitCtor<_Dummy, const _T1&, const _T2&> = false>
1069 explicit constexpr
1070 tuple(const _T1& __a1, const _T2& __a2)
1071 noexcept(__nothrow_constructible<const _T1&, const _T2&>())
1072 : _Inherited(__a1, __a2) { }
1073
1074 template<typename _U1, typename _U2,
1075 _ImplicitCtor<!__is_alloc_arg<_U1>(), _U1, _U2> = true>
1076 constexpr
1077 tuple(_U1&& __a1, _U2&& __a2)
1078 noexcept(__nothrow_constructible<_U1, _U2>())
1079 : _Inherited(std::forward<_U1>(__a1), std::forward<_U2>(__a2)) { }
1080
1081 template<typename _U1, typename _U2,
1082 _ExplicitCtor<!__is_alloc_arg<_U1>(), _U1, _U2> = false>
1083 explicit constexpr
1084 tuple(_U1&& __a1, _U2&& __a2)
1085 noexcept(__nothrow_constructible<_U1, _U2>())
1086 : _Inherited(std::forward<_U1>(__a1), std::forward<_U2>(__a2)) { }
1087
1088 constexpr tuple(const tuple&) = default;
1089
1090 constexpr tuple(tuple&&) = default;
1091
1092 template<typename _U1, typename _U2,
1093 _ImplicitCtor<true, const _U1&, const _U2&> = true>
1094 constexpr
1095 tuple(const tuple<_U1, _U2>& __in)
1096 noexcept(__nothrow_constructible<const _U1&, const _U2&>())
1097 : _Inherited(static_cast<const _Tuple_impl<0, _U1, _U2>&>(__in)) { }
1098
1099 template<typename _U1, typename _U2,
1100 _ExplicitCtor<true, const _U1&, const _U2&> = false>
1101 explicit constexpr
1102 tuple(const tuple<_U1, _U2>& __in)
1103 noexcept(__nothrow_constructible<const _U1&, const _U2&>())
1104 : _Inherited(static_cast<const _Tuple_impl<0, _U1, _U2>&>(__in)) { }
1105
1106 template<typename _U1, typename _U2,
1107 _ImplicitCtor<true, _U1, _U2> = true>
1108 constexpr
1109 tuple(tuple<_U1, _U2>&& __in)
1110 noexcept(__nothrow_constructible<_U1, _U2>())
1111 : _Inherited(static_cast<_Tuple_impl<0, _U1, _U2>&&>(__in)) { }
1112
1113 template<typename _U1, typename _U2,
1114 _ExplicitCtor<true, _U1, _U2> = false>
1115 explicit constexpr
1116 tuple(tuple<_U1, _U2>&& __in)
1117 noexcept(__nothrow_constructible<_U1, _U2>())
1118 : _Inherited(static_cast<_Tuple_impl<0, _U1, _U2>&&>(__in)) { }
1119
1120 template<typename _U1, typename _U2,
1121 _ImplicitCtor<true, const _U1&, const _U2&> = true>
1122 constexpr
1123 tuple(const pair<_U1, _U2>& __in)
1124 noexcept(__nothrow_constructible<const _U1&, const _U2&>())
1125 : _Inherited(__in.first, __in.second) { }
1126
1127 template<typename _U1, typename _U2,
1128 _ExplicitCtor<true, const _U1&, const _U2&> = false>
1129 explicit constexpr
1130 tuple(const pair<_U1, _U2>& __in)
1131 noexcept(__nothrow_constructible<const _U1&, const _U2&>())
1132 : _Inherited(__in.first, __in.second) { }
1133
1134 template<typename _U1, typename _U2,
1135 _ImplicitCtor<true, _U1, _U2> = true>
1136 constexpr
1137 tuple(pair<_U1, _U2>&& __in)
1138 noexcept(__nothrow_constructible<_U1, _U2>())
1139 : _Inherited(std::forward<_U1>(__in.first),
1140 std::forward<_U2>(__in.second)) { }
1141
1142 template<typename _U1, typename _U2,
1143 _ExplicitCtor<true, _U1, _U2> = false>
1144 explicit constexpr
1145 tuple(pair<_U1, _U2>&& __in)
1146 noexcept(__nothrow_constructible<_U1, _U2>())
1147 : _Inherited(std::forward<_U1>(__in.first),
1148 std::forward<_U2>(__in.second)) { }
1149
1150 // Allocator-extended constructors.
1151
1152 template<typename _Alloc,
1153 _ImplicitDefaultCtor<is_object<_Alloc>::value, _T1, _T2> = true>
1154 _GLIBCXX20_CONSTEXPR
1155 tuple(allocator_arg_t __tag, const _Alloc& __a)
1156 : _Inherited(__tag, __a) { }
1157
1158 template<typename _Alloc, bool _Dummy = true,
1159 _ImplicitCtor<_Dummy, const _T1&, const _T2&> = true>
1160 _GLIBCXX20_CONSTEXPR
1161 tuple(allocator_arg_t __tag, const _Alloc& __a,
1162 const _T1& __a1, const _T2& __a2)
1163 : _Inherited(__tag, __a, __a1, __a2) { }
1164
1165 template<typename _Alloc, bool _Dummy = true,
1166 _ExplicitCtor<_Dummy, const _T1&, const _T2&> = false>
1167 explicit
1168 _GLIBCXX20_CONSTEXPR
1169 tuple(allocator_arg_t __tag, const _Alloc& __a,
1170 const _T1& __a1, const _T2& __a2)
1171 : _Inherited(__tag, __a, __a1, __a2) { }
1172
1173 template<typename _Alloc, typename _U1, typename _U2,
1174 _ImplicitCtor<true, _U1, _U2> = true>
1175 _GLIBCXX20_CONSTEXPR
1176 tuple(allocator_arg_t __tag, const _Alloc& __a, _U1&& __a1, _U2&& __a2)
1177 : _Inherited(__tag, __a, std::forward<_U1>(__a1),
1178 std::forward<_U2>(__a2)) { }
1179
1180 template<typename _Alloc, typename _U1, typename _U2,
1181 _ExplicitCtor<true, _U1, _U2> = false>
1182 explicit
1183 _GLIBCXX20_CONSTEXPR
1184 tuple(allocator_arg_t __tag, const _Alloc& __a,
1185 _U1&& __a1, _U2&& __a2)
1186 : _Inherited(__tag, __a, std::forward<_U1>(__a1),
1187 std::forward<_U2>(__a2)) { }
1188
1189 template<typename _Alloc>
1190 _GLIBCXX20_CONSTEXPR
1191 tuple(allocator_arg_t __tag, const _Alloc& __a, const tuple& __in)
1192 : _Inherited(__tag, __a, static_cast<const _Inherited&>(__in)) { }
1193
1194 template<typename _Alloc>
1195 _GLIBCXX20_CONSTEXPR
1196 tuple(allocator_arg_t __tag, const _Alloc& __a, tuple&& __in)
1197 : _Inherited(__tag, __a, static_cast<_Inherited&&>(__in)) { }
1198
1199 template<typename _Alloc, typename _U1, typename _U2,
1200 _ImplicitCtor<true, const _U1&, const _U2&> = true>
1201 _GLIBCXX20_CONSTEXPR
1202 tuple(allocator_arg_t __tag, const _Alloc& __a,
1203 const tuple<_U1, _U2>& __in)
1204 : _Inherited(__tag, __a,
1205 static_cast<const _Tuple_impl<0, _U1, _U2>&>(__in))
1206 { }
1207
1208 template<typename _Alloc, typename _U1, typename _U2,
1209 _ExplicitCtor<true, const _U1&, const _U2&> = false>
1210 explicit
1211 _GLIBCXX20_CONSTEXPR
1212 tuple(allocator_arg_t __tag, const _Alloc& __a,
1213 const tuple<_U1, _U2>& __in)
1214 : _Inherited(__tag, __a,
1215 static_cast<const _Tuple_impl<0, _U1, _U2>&>(__in))
1216 { }
1217
1218 template<typename _Alloc, typename _U1, typename _U2,
1219 _ImplicitCtor<true, _U1, _U2> = true>
1220 _GLIBCXX20_CONSTEXPR
1221 tuple(allocator_arg_t __tag, const _Alloc& __a, tuple<_U1, _U2>&& __in)
1222 : _Inherited(__tag, __a, static_cast<_Tuple_impl<0, _U1, _U2>&&>(__in))
1223 { }
1224
1225 template<typename _Alloc, typename _U1, typename _U2,
1226 _ExplicitCtor<true, _U1, _U2> = false>
1227 explicit
1228 _GLIBCXX20_CONSTEXPR
1229 tuple(allocator_arg_t __tag, const _Alloc& __a, tuple<_U1, _U2>&& __in)
1230 : _Inherited(__tag, __a, static_cast<_Tuple_impl<0, _U1, _U2>&&>(__in))
1231 { }
1232
1233 template<typename _Alloc, typename _U1, typename _U2,
1234 _ImplicitCtor<true, const _U1&, const _U2&> = true>
1235 _GLIBCXX20_CONSTEXPR
1236 tuple(allocator_arg_t __tag, const _Alloc& __a,
1237 const pair<_U1, _U2>& __in)
1238 : _Inherited(__tag, __a, __in.first, __in.second) { }
1239
1240 template<typename _Alloc, typename _U1, typename _U2,
1241 _ExplicitCtor<true, const _U1&, const _U2&> = false>
1242 explicit
1243 _GLIBCXX20_CONSTEXPR
1244 tuple(allocator_arg_t __tag, const _Alloc& __a,
1245 const pair<_U1, _U2>& __in)
1246 : _Inherited(__tag, __a, __in.first, __in.second) { }
1247
1248 template<typename _Alloc, typename _U1, typename _U2,
1249 _ImplicitCtor<true, _U1, _U2> = true>
1250 _GLIBCXX20_CONSTEXPR
1251 tuple(allocator_arg_t __tag, const _Alloc& __a, pair<_U1, _U2>&& __in)
1252 : _Inherited(__tag, __a, std::forward<_U1>(__in.first),
1253 std::forward<_U2>(__in.second)) { }
1254
1255 template<typename _Alloc, typename _U1, typename _U2,
1256 _ExplicitCtor<true, _U1, _U2> = false>
1257 explicit
1258 _GLIBCXX20_CONSTEXPR
1259 tuple(allocator_arg_t __tag, const _Alloc& __a, pair<_U1, _U2>&& __in)
1260 : _Inherited(__tag, __a, std::forward<_U1>(__in.first),
1261 std::forward<_U2>(__in.second)) { }
1262
1263 // Tuple assignment.
1264
1265 _GLIBCXX20_CONSTEXPR
1266 tuple&
1267 operator=(typename conditional<__assignable<const _T1&, const _T2&>(),
1268 const tuple&,
1269 const __nonesuch&>::type __in)
1270 noexcept(__nothrow_assignable<const _T1&, const _T2&>())
1271 {
1272 this->_M_assign(__in);
1273 return *this;
1274 }
1275
1276 _GLIBCXX20_CONSTEXPR
1277 tuple&
1278 operator=(typename conditional<__assignable<_T1, _T2>(),
1279 tuple&&,
1280 __nonesuch&&>::type __in)
1281 noexcept(__nothrow_assignable<_T1, _T2>())
1282 {
1283 this->_M_assign(std::move(__in));
1284 return *this;
1285 }
1286
1287 template<typename _U1, typename _U2>
1288 _GLIBCXX20_CONSTEXPR
1289 __enable_if_t<__assignable<const _U1&, const _U2&>(), tuple&>
1290 operator=(const tuple<_U1, _U2>& __in)
1291 noexcept(__nothrow_assignable<const _U1&, const _U2&>())
1292 {
1293 this->_M_assign(__in);
1294 return *this;
1295 }
1296
1297 template<typename _U1, typename _U2>
1298 _GLIBCXX20_CONSTEXPR
1299 __enable_if_t<__assignable<_U1, _U2>(), tuple&>
1300 operator=(tuple<_U1, _U2>&& __in)
1301 noexcept(__nothrow_assignable<_U1, _U2>())
1302 {
1303 this->_M_assign(std::move(__in));
1304 return *this;
1305 }
1306
1307 template<typename _U1, typename _U2>
1308 _GLIBCXX20_CONSTEXPR
1309 __enable_if_t<__assignable<const _U1&, const _U2&>(), tuple&>
1310 operator=(const pair<_U1, _U2>& __in)
1311 noexcept(__nothrow_assignable<const _U1&, const _U2&>())
1312 {
1313 this->_M_head(*this) = __in.first;
1314 this->_M_tail(*this)._M_head(*this) = __in.second;
1315 return *this;
1316 }
1317
1318 template<typename _U1, typename _U2>
1319 _GLIBCXX20_CONSTEXPR
1320 __enable_if_t<__assignable<_U1, _U2>(), tuple&>
1321 operator=(pair<_U1, _U2>&& __in)
1322 noexcept(__nothrow_assignable<_U1, _U2>())
1323 {
1324 this->_M_head(*this) = std::forward<_U1>(__in.first);
1325 this->_M_tail(*this)._M_head(*this) = std::forward<_U2>(__in.second);
1326 return *this;
1327 }
1328
1329 _GLIBCXX20_CONSTEXPR
1330 void
1331 swap(tuple& __in)
1332 noexcept(__and_<__is_nothrow_swappable<_T1>,
1333 __is_nothrow_swappable<_T2>>::value)
1334 { _Inherited::_M_swap(__in); }
1335 };
1336
1337
1338 /// class tuple_size
1339 template<typename... _Elements>
1340 struct tuple_size<tuple<_Elements...>>
1341 : public integral_constant<size_t, sizeof...(_Elements)> { };
1342
1343#if __cplusplus > 201402L
1344 template <typename _Tp>
1345 inline constexpr size_t tuple_size_v = tuple_size<_Tp>::value;
1346#endif
1347
1348 /**
1349 * Recursive case for tuple_element: strip off the first element in
1350 * the tuple and retrieve the (i-1)th element of the remaining tuple.
1351 */
1352 template<size_t __i, typename _Head, typename... _Tail>
1353 struct tuple_element<__i, tuple<_Head, _Tail...> >
1354 : tuple_element<__i - 1, tuple<_Tail...> > { };
1355
1356 /**
1357 * Basis case for tuple_element: The first element is the one we're seeking.
1358 */
1359 template<typename _Head, typename... _Tail>
1360 struct tuple_element<0, tuple<_Head, _Tail...> >
1361 {
1362 typedef _Head type;
1363 };
1364
1365 /**
1366 * Error case for tuple_element: invalid index.
1367 */
1368 template<size_t __i>
1369 struct tuple_element<__i, tuple<>>
1370 {
1371 static_assert(__i < tuple_size<tuple<>>::value,
1372 "tuple index must be in range");
1373 };
1374
1375 template<size_t __i, typename _Head, typename... _Tail>
1376 constexpr _Head&
1377 __get_helper(_Tuple_impl<__i, _Head, _Tail...>& __t) noexcept
1378 { return _Tuple_impl<__i, _Head, _Tail...>::_M_head(__t); }
1379
1380 template<size_t __i, typename _Head, typename... _Tail>
1381 constexpr const _Head&
1382 __get_helper(const _Tuple_impl<__i, _Head, _Tail...>& __t) noexcept
1383 { return _Tuple_impl<__i, _Head, _Tail...>::_M_head(__t); }
1384
1385 // Deleted overload to improve diagnostics for invalid indices
1386 template<size_t __i, typename... _Types>
1387 __enable_if_t<(__i >= sizeof...(_Types))>
1388 __get_helper(const tuple<_Types...>&) = delete;
1389
1390 /// Return a reference to the ith element of a tuple.
1391 template<size_t __i, typename... _Elements>
1392 constexpr __tuple_element_t<__i, tuple<_Elements...>>&
1393 get(tuple<_Elements...>& __t) noexcept
1394 { return std::__get_helper<__i>(__t); }
1395
1396 /// Return a const reference to the ith element of a const tuple.
1397 template<size_t __i, typename... _Elements>
1398 constexpr const __tuple_element_t<__i, tuple<_Elements...>>&
1399 get(const tuple<_Elements...>& __t) noexcept
1400 { return std::__get_helper<__i>(__t); }
1401
1402 /// Return an rvalue reference to the ith element of a tuple rvalue.
1403 template<size_t __i, typename... _Elements>
1404 constexpr __tuple_element_t<__i, tuple<_Elements...>>&&
1405 get(tuple<_Elements...>&& __t) noexcept
1406 {
1407 typedef __tuple_element_t<__i, tuple<_Elements...>> __element_type;
1408 return std::forward<__element_type>(std::__get_helper<__i>(__t));
1409 }
1410
1411 /// Return a const rvalue reference to the ith element of a const tuple rvalue.
1412 template<size_t __i, typename... _Elements>
1413 constexpr const __tuple_element_t<__i, tuple<_Elements...>>&&
1414 get(const tuple<_Elements...>&& __t) noexcept
1415 {
1416 typedef __tuple_element_t<__i, tuple<_Elements...>> __element_type;
1417 return std::forward<const __element_type>(std::__get_helper<__i>(__t));
1418 }
1419
1420#if __cplusplus >= 201402L
1421
1422#define __cpp_lib_tuples_by_type 201304
1423
1424 // Return the index of _Tp in _Types, if it occurs exactly once.
1425 // Otherwise, return sizeof...(_Types).
1426 // TODO reuse this for __detail::__variant::__exactly_once.
1427 template<typename _Tp, typename... _Types>
1428 constexpr size_t
1429 __find_uniq_type_in_pack()
1430 {
1431 constexpr size_t __sz = sizeof...(_Types);
1432 constexpr bool __found[__sz] = { __is_same(_Tp, _Types) ... };
1433 size_t __n = __sz;
1434 for (size_t __i = 0; __i < __sz; ++__i)
1435 {
1436 if (__found[__i])
1437 {
1438 if (__n < __sz) // more than one _Tp found
1439 return __sz;
1440 __n = __i;
1441 }
1442 }
1443 return __n;
1444 }
1445
1446 /// Return a reference to the unique element of type _Tp of a tuple.
1447 template <typename _Tp, typename... _Types>
1448 constexpr _Tp&
1449 get(tuple<_Types...>& __t) noexcept
1450 {
1451 constexpr size_t __idx = __find_uniq_type_in_pack<_Tp, _Types...>();
1452 static_assert(__idx < sizeof...(_Types),
1453 "the type T in std::get<T> must occur exactly once in the tuple");
1454 return std::__get_helper<__idx>(__t);
1455 }
1456
1457 /// Return a reference to the unique element of type _Tp of a tuple rvalue.
1458 template <typename _Tp, typename... _Types>
1459 constexpr _Tp&&
1460 get(tuple<_Types...>&& __t) noexcept
1461 {
1462 constexpr size_t __idx = __find_uniq_type_in_pack<_Tp, _Types...>();
1463 static_assert(__idx < sizeof...(_Types),
1464 "the type T in std::get<T> must occur exactly once in the tuple");
1465 return std::forward<_Tp>(std::__get_helper<__idx>(__t));
1466 }
1467
1468 /// Return a const reference to the unique element of type _Tp of a tuple.
1469 template <typename _Tp, typename... _Types>
1470 constexpr const _Tp&
1471 get(const tuple<_Types...>& __t) noexcept
1472 {
1473 constexpr size_t __idx = __find_uniq_type_in_pack<_Tp, _Types...>();
1474 static_assert(__idx < sizeof...(_Types),
1475 "the type T in std::get<T> must occur exactly once in the tuple");
1476 return std::__get_helper<__idx>(__t);
1477 }
1478
1479 /// Return a const reference to the unique element of type _Tp of
1480 /// a const tuple rvalue.
1481 template <typename _Tp, typename... _Types>
1482 constexpr const _Tp&&
1483 get(const tuple<_Types...>&& __t) noexcept
1484 {
1485 constexpr size_t __idx = __find_uniq_type_in_pack<_Tp, _Types...>();
1486 static_assert(__idx < sizeof...(_Types),
1487 "the type T in std::get<T> must occur exactly once in the tuple");
1488 return std::forward<const _Tp>(std::__get_helper<__idx>(__t));
1489 }
1490#endif
1491
1492 // This class performs the comparison operations on tuples
1493 template<typename _Tp, typename _Up, size_t __i, size_t __size>
1494 struct __tuple_compare
1495 {
1496 static constexpr bool
1497 __eq(const _Tp& __t, const _Up& __u)
1498 {
1499 return bool(std::get<__i>(__t) == std::get<__i>(__u))
1500 && __tuple_compare<_Tp, _Up, __i + 1, __size>::__eq(__t, __u);
1501 }
1502
1503 static constexpr bool
1504 __less(const _Tp& __t, const _Up& __u)
1505 {
1506 return bool(std::get<__i>(__t) < std::get<__i>(__u))
1507 || (!bool(std::get<__i>(__u) < std::get<__i>(__t))
1508 && __tuple_compare<_Tp, _Up, __i + 1, __size>::__less(__t, __u));
1509 }
1510 };
1511
1512 template<typename _Tp, typename _Up, size_t __size>
1513 struct __tuple_compare<_Tp, _Up, __size, __size>
1514 {
1515 static constexpr bool
1516 __eq(const _Tp&, const _Up&) { return true; }
1517
1518 static constexpr bool
1519 __less(const _Tp&, const _Up&) { return false; }
1520 };
1521
1522 template<typename... _TElements, typename... _UElements>
1523 constexpr bool
1524 operator==(const tuple<_TElements...>& __t,
1525 const tuple<_UElements...>& __u)
1526 {
1527 static_assert(sizeof...(_TElements) == sizeof...(_UElements),
1528 "tuple objects can only be compared if they have equal sizes.");
1529 using __compare = __tuple_compare<tuple<_TElements...>,
1530 tuple<_UElements...>,
1531 0, sizeof...(_TElements)>;
1532 return __compare::__eq(__t, __u);
1533 }
1534
1535#if __cpp_lib_three_way_comparison
1536 template<typename _Cat, typename _Tp, typename _Up>
1537 constexpr _Cat
1538 __tuple_cmp(const _Tp&, const _Up&, index_sequence<>)
1539 { return _Cat::equivalent; }
1540
1541 template<typename _Cat, typename _Tp, typename _Up,
1542 size_t _Idx0, size_t... _Idxs>
1543 constexpr _Cat
1544 __tuple_cmp(const _Tp& __t, const _Up& __u,
1545 index_sequence<_Idx0, _Idxs...>)
1546 {
1547 auto __c
1548 = __detail::__synth3way(std::get<_Idx0>(__t), std::get<_Idx0>(__u));
1549 if (__c != 0)
1550 return __c;
1551 return std::__tuple_cmp<_Cat>(__t, __u, index_sequence<_Idxs...>());
1552 }
1553
1554 template<typename... _Tps, typename... _Ups>
1555 constexpr
1556 common_comparison_category_t<__detail::__synth3way_t<_Tps, _Ups>...>
1557 operator<=>(const tuple<_Tps...>& __t, const tuple<_Ups...>& __u)
1558 {
1559 using _Cat
1560 = common_comparison_category_t<__detail::__synth3way_t<_Tps, _Ups>...>;
1561 return std::__tuple_cmp<_Cat>(__t, __u, index_sequence_for<_Tps...>());
1562 }
1563#else
1564 template<typename... _TElements, typename... _UElements>
1565 constexpr bool
1566 operator<(const tuple<_TElements...>& __t,
1567 const tuple<_UElements...>& __u)
1568 {
1569 static_assert(sizeof...(_TElements) == sizeof...(_UElements),
1570 "tuple objects can only be compared if they have equal sizes.");
1571 using __compare = __tuple_compare<tuple<_TElements...>,
1572 tuple<_UElements...>,
1573 0, sizeof...(_TElements)>;
1574 return __compare::__less(__t, __u);
1575 }
1576
1577 template<typename... _TElements, typename... _UElements>
1578 constexpr bool
1579 operator!=(const tuple<_TElements...>& __t,
1580 const tuple<_UElements...>& __u)
1581 { return !(__t == __u); }
1582
1583 template<typename... _TElements, typename... _UElements>
1584 constexpr bool
1585 operator>(const tuple<_TElements...>& __t,
1586 const tuple<_UElements...>& __u)
1587 { return __u < __t; }
1588
1589 template<typename... _TElements, typename... _UElements>
1590 constexpr bool
1591 operator<=(const tuple<_TElements...>& __t,
1592 const tuple<_UElements...>& __u)
1593 { return !(__u < __t); }
1594
1595 template<typename... _TElements, typename... _UElements>
1596 constexpr bool
1597 operator>=(const tuple<_TElements...>& __t,
1598 const tuple<_UElements...>& __u)
1599 { return !(__t < __u); }
1600#endif // three_way_comparison
1601
1602 // NB: DR 705.
1603 template<typename... _Elements>
1604 constexpr tuple<typename __decay_and_strip<_Elements>::__type...>
1605 make_tuple(_Elements&&... __args)
1606 {
1607 typedef tuple<typename __decay_and_strip<_Elements>::__type...>
1608 __result_type;
1609 return __result_type(std::forward<_Elements>(__args)...);
1610 }
1611
1612 // _GLIBCXX_RESOLVE_LIB_DEFECTS
1613 // 2275. Why is forward_as_tuple not constexpr?
1614 /// std::forward_as_tuple
1615 template<typename... _Elements>
1616 constexpr tuple<_Elements&&...>
1617 forward_as_tuple(_Elements&&... __args) noexcept
1618 { return tuple<_Elements&&...>(std::forward<_Elements>(__args)...); }
1619
1620 template<size_t, typename, typename, size_t>
1621 struct __make_tuple_impl;
1622
1623 template<size_t _Idx, typename _Tuple, typename... _Tp, size_t _Nm>
1624 struct __make_tuple_impl<_Idx, tuple<_Tp...>, _Tuple, _Nm>
1625 : __make_tuple_impl<_Idx + 1,
1626 tuple<_Tp..., __tuple_element_t<_Idx, _Tuple>>,
1627 _Tuple, _Nm>
1628 { };
1629
1630 template<size_t _Nm, typename _Tuple, typename... _Tp>
1631 struct __make_tuple_impl<_Nm, tuple<_Tp...>, _Tuple, _Nm>
1632 {
1633 typedef tuple<_Tp...> __type;
1634 };
1635
1636 template<typename _Tuple>
1637 struct __do_make_tuple
1638 : __make_tuple_impl<0, tuple<>, _Tuple, tuple_size<_Tuple>::value>
1639 { };
1640
1641 // Returns the std::tuple equivalent of a tuple-like type.
1642 template<typename _Tuple>
1643 struct __make_tuple
1644 : public __do_make_tuple<__remove_cvref_t<_Tuple>>
1645 { };
1646
1647 // Combines several std::tuple's into a single one.
1648 template<typename...>
1649 struct __combine_tuples;
1650
1651 template<>
1652 struct __combine_tuples<>
1653 {
1654 typedef tuple<> __type;
1655 };
1656
1657 template<typename... _Ts>
1658 struct __combine_tuples<tuple<_Ts...>>
1659 {
1660 typedef tuple<_Ts...> __type;
1661 };
1662
1663 template<typename... _T1s, typename... _T2s, typename... _Rem>
1664 struct __combine_tuples<tuple<_T1s...>, tuple<_T2s...>, _Rem...>
1665 {
1666 typedef typename __combine_tuples<tuple<_T1s..., _T2s...>,
1667 _Rem...>::__type __type;
1668 };
1669
1670 // Computes the result type of tuple_cat given a set of tuple-like types.
1671 template<typename... _Tpls>
1672 struct __tuple_cat_result
1673 {
1674 typedef typename __combine_tuples
1675 <typename __make_tuple<_Tpls>::__type...>::__type __type;
1676 };
1677
1678 // Helper to determine the index set for the first tuple-like
1679 // type of a given set.
1680 template<typename...>
1681 struct __make_1st_indices;
1682
1683 template<>
1684 struct __make_1st_indices<>
1685 {
1686 typedef _Index_tuple<> __type;
1687 };
1688
1689 template<typename _Tp, typename... _Tpls>
1690 struct __make_1st_indices<_Tp, _Tpls...>
1691 {
1692 typedef typename _Build_index_tuple<tuple_size<
1693 typename remove_reference<_Tp>::type>::value>::__type __type;
1694 };
1695
1696 // Performs the actual concatenation by step-wise expanding tuple-like
1697 // objects into the elements, which are finally forwarded into the
1698 // result tuple.
1699 template<typename _Ret, typename _Indices, typename... _Tpls>
1700 struct __tuple_concater;
1701
1702 template<typename _Ret, size_t... _Is, typename _Tp, typename... _Tpls>
1703 struct __tuple_concater<_Ret, _Index_tuple<_Is...>, _Tp, _Tpls...>
1704 {
1705 template<typename... _Us>
1706 static constexpr _Ret
1707 _S_do(_Tp&& __tp, _Tpls&&... __tps, _Us&&... __us)
1708 {
1709 typedef typename __make_1st_indices<_Tpls...>::__type __idx;
1710 typedef __tuple_concater<_Ret, __idx, _Tpls...> __next;
1711 return __next::_S_do(std::forward<_Tpls>(__tps)...,
1712 std::forward<_Us>(__us)...,
1713 std::get<_Is>(std::forward<_Tp>(__tp))...);
1714 }
1715 };
1716
1717 template<typename _Ret>
1718 struct __tuple_concater<_Ret, _Index_tuple<>>
1719 {
1720 template<typename... _Us>
1721 static constexpr _Ret
1722 _S_do(_Us&&... __us)
1723 {
1724 return _Ret(std::forward<_Us>(__us)...);
1725 }
1726 };
1727
1728 /// tuple_cat
1729 template<typename... _Tpls, typename = typename
1730 enable_if<__and_<__is_tuple_like<_Tpls>...>::value>::type>
1731 constexpr auto
1732 tuple_cat(_Tpls&&... __tpls)
1733 -> typename __tuple_cat_result<_Tpls...>::__type
1734 {
1735 typedef typename __tuple_cat_result<_Tpls...>::__type __ret;
1736 typedef typename __make_1st_indices<_Tpls...>::__type __idx;
1737 typedef __tuple_concater<__ret, __idx, _Tpls...> __concater;
1738 return __concater::_S_do(std::forward<_Tpls>(__tpls)...);
1739 }
1740
1741 // _GLIBCXX_RESOLVE_LIB_DEFECTS
1742 // 2301. Why is tie not constexpr?
1743 /// tie
1744 template<typename... _Elements>
1745 constexpr tuple<_Elements&...>
1746 tie(_Elements&... __args) noexcept
1747 { return tuple<_Elements&...>(__args...); }
1748
1749 /// swap
1750 template<typename... _Elements>
1751 _GLIBCXX20_CONSTEXPR
1752 inline
1753#if __cplusplus > 201402L || !defined(__STRICT_ANSI__) // c++1z or gnu++11
1754 // Constrained free swap overload, see p0185r1
1755 typename enable_if<__and_<__is_swappable<_Elements>...>::value
1756 >::type
1757#else
1758 void
1759#endif
1760 swap(tuple<_Elements...>& __x, tuple<_Elements...>& __y)
1761 noexcept(noexcept(__x.swap(__y)))
1762 { __x.swap(__y); }
1763
1764#if __cplusplus > 201402L || !defined(__STRICT_ANSI__) // c++1z or gnu++11
1765 template<typename... _Elements>
1766 _GLIBCXX20_CONSTEXPR
1767 typename enable_if<!__and_<__is_swappable<_Elements>...>::value>::type
1768 swap(tuple<_Elements...>&, tuple<_Elements...>&) = delete;
1769#endif
1770
1771 // A class (and instance) which can be used in 'tie' when an element
1772 // of a tuple is not required.
1773 // _GLIBCXX14_CONSTEXPR
1774 // 2933. PR for LWG 2773 could be clearer
1775 struct _Swallow_assign
1776 {
1777 template<class _Tp>
1778 _GLIBCXX14_CONSTEXPR const _Swallow_assign&
1779 operator=(const _Tp&) const
1780 { return *this; }
1781 };
1782
1783 // _GLIBCXX_RESOLVE_LIB_DEFECTS
1784 // 2773. Making std::ignore constexpr
1785 _GLIBCXX17_INLINE constexpr _Swallow_assign ignore{};
1786
1787 /// Partial specialization for tuples
1788 template<typename... _Types, typename _Alloc>
1789 struct uses_allocator<tuple<_Types...>, _Alloc> : true_type { };
1790
1791 // See stl_pair.h...
1792 /** "piecewise construction" using a tuple of arguments for each member.
1793 *
1794 * @param __first Arguments for the first member of the pair.
1795 * @param __second Arguments for the second member of the pair.
1796 *
1797 * The elements of each tuple will be used as the constructor arguments
1798 * for the data members of the pair.
1799 */
1800 template<class _T1, class _T2>
1801 template<typename... _Args1, typename... _Args2>
1802 _GLIBCXX20_CONSTEXPR
1803 inline
1804 pair<_T1, _T2>::
1805 pair(piecewise_construct_t,
1806 tuple<_Args1...> __first, tuple<_Args2...> __second)
1807 : pair(__first, __second,
1808 typename _Build_index_tuple<sizeof...(_Args1)>::__type(),
1809 typename _Build_index_tuple<sizeof...(_Args2)>::__type())
1810 { }
1811
1812 template<class _T1, class _T2>
1813 template<typename... _Args1, size_t... _Indexes1,
1814 typename... _Args2, size_t... _Indexes2>
1815 _GLIBCXX20_CONSTEXPR inline
1816 pair<_T1, _T2>::
1817 pair(tuple<_Args1...>& __tuple1, tuple<_Args2...>& __tuple2,
1818 _Index_tuple<_Indexes1...>, _Index_tuple<_Indexes2...>)
1819 : first(std::forward<_Args1>(std::get<_Indexes1>(__tuple1))...),
1820 second(std::forward<_Args2>(std::get<_Indexes2>(__tuple2))...)
1821 { }
1822
1823#if __cplusplus >= 201703L
1824
1825 // Unpack a std::tuple into a type trait and use its value.
1826 // For cv std::tuple<_Up> the result is _Trait<_Tp, cv _Up...>::value.
1827 // For cv std::tuple<_Up>& the result is _Trait<_Tp, cv _Up&...>::value.
1828 // Otherwise the result is false (because we don't know if std::get throws).
1829 template<template<typename...> class _Trait, typename _Tp, typename _Tuple>
1830 inline constexpr bool __unpack_std_tuple = false;
1831
1832 template<template<typename...> class _Trait, typename _Tp, typename... _Up>
1833 inline constexpr bool __unpack_std_tuple<_Trait, _Tp, tuple<_Up...>>
1834 = _Trait<_Tp, _Up...>::value;
1835
1836 template<template<typename...> class _Trait, typename _Tp, typename... _Up>
1837 inline constexpr bool __unpack_std_tuple<_Trait, _Tp, tuple<_Up...>&>
1838 = _Trait<_Tp, _Up&...>::value;
1839
1840 template<template<typename...> class _Trait, typename _Tp, typename... _Up>
1841 inline constexpr bool __unpack_std_tuple<_Trait, _Tp, const tuple<_Up...>>
1842 = _Trait<_Tp, const _Up...>::value;
1843
1844 template<template<typename...> class _Trait, typename _Tp, typename... _Up>
1845 inline constexpr bool __unpack_std_tuple<_Trait, _Tp, const tuple<_Up...>&>
1846 = _Trait<_Tp, const _Up&...>::value;
1847
1848# define __cpp_lib_apply 201603
1849
1850 template <typename _Fn, typename _Tuple, size_t... _Idx>
1851 constexpr decltype(auto)
1852 __apply_impl(_Fn&& __f, _Tuple&& __t, index_sequence<_Idx...>)
1853 {
1854 return std::__invoke(std::forward<_Fn>(__f),
1855 std::get<_Idx>(std::forward<_Tuple>(__t))...);
1856 }
1857
1858 template <typename _Fn, typename _Tuple>
1859 constexpr decltype(auto)
1860 apply(_Fn&& __f, _Tuple&& __t)
1861 noexcept(__unpack_std_tuple<is_nothrow_invocable, _Fn, _Tuple>)
1862 {
1863 using _Indices
1864 = make_index_sequence<tuple_size_v<remove_reference_t<_Tuple>>>;
1865 return std::__apply_impl(std::forward<_Fn>(__f),
1866 std::forward<_Tuple>(__t),
1867 _Indices{});
1868 }
1869
1870#define __cpp_lib_make_from_tuple 201606
1871
1872 template <typename _Tp, typename _Tuple, size_t... _Idx>
1873 constexpr _Tp
1874 __make_from_tuple_impl(_Tuple&& __t, index_sequence<_Idx...>)
1875 { return _Tp(std::get<_Idx>(std::forward<_Tuple>(__t))...); }
1876
1877 template <typename _Tp, typename _Tuple>
1878 constexpr _Tp
1879 make_from_tuple(_Tuple&& __t)
1880 noexcept(__unpack_std_tuple<is_nothrow_constructible, _Tp, _Tuple>)
1881 {
1882 return __make_from_tuple_impl<_Tp>(
1883 std::forward<_Tuple>(__t),
1884 make_index_sequence<tuple_size_v<remove_reference_t<_Tuple>>>{});
1885 }
1886#endif // C++17
1887
1888 /// @}
1889
1890_GLIBCXX_END_NAMESPACE_VERSION
1891} // namespace std
1892
1893#endif // C++11
1894
1895#endif // _GLIBCXX_TUPLE
1896

source code of include/c++/11/tuple