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 template<typename _Tp, typename _Up> // Workaround for PR 96592
557 using is_constructible
558 = __bool_constant<__is_constructible(_Tp, _Up)>;
559
560 // Constraint for a non-explicit constructor.
561 // True iff each Ti in _Types... can be constructed from Ui in _UTypes...
562 // and every Ui is implicitly convertible to Ti.
563 template<typename... _UTypes>
564 static constexpr bool __is_implicitly_constructible()
565 {
566 return __and_<is_constructible<_Types, _UTypes>...,
567 is_convertible<_UTypes, _Types>...
568 >::value;
569 }
570
571 // Constraint for a non-explicit constructor.
572 // True iff each Ti in _Types... can be constructed from Ui in _UTypes...
573 // but not every Ui is implicitly convertible to Ti.
574 template<typename... _UTypes>
575 static constexpr bool __is_explicitly_constructible()
576 {
577 return __and_<is_constructible<_Types, _UTypes>...,
578 __not_<__and_<is_convertible<_UTypes, _Types>...>>
579 >::value;
580 }
581
582 static constexpr bool __is_implicitly_default_constructible()
583 {
584 return __and_<std::__is_implicitly_default_constructible<_Types>...
585 >::value;
586 }
587
588 static constexpr bool __is_explicitly_default_constructible()
589 {
590 return __and_<is_default_constructible<_Types>...,
591 __not_<__and_<
592 std::__is_implicitly_default_constructible<_Types>...>
593 >>::value;
594 }
595 };
596
597 // Partial specialization used when a required precondition isn't met,
598 // e.g. when sizeof...(_Types) != sizeof...(_UTypes).
599 template<typename... _Types>
600 struct _TupleConstraints<false, _Types...>
601 {
602 template<typename... _UTypes>
603 static constexpr bool __is_implicitly_constructible()
604 { return false; }
605
606 template<typename... _UTypes>
607 static constexpr bool __is_explicitly_constructible()
608 { return false; }
609 };
610
611 /// Primary class template, tuple
612 template<typename... _Elements>
613 class tuple : public _Tuple_impl<0, _Elements...>
614 {
615 typedef _Tuple_impl<0, _Elements...> _Inherited;
616
617 template<bool _Cond>
618 using _TCC = _TupleConstraints<_Cond, _Elements...>;
619
620 // Constraint for non-explicit default constructor
621 template<bool _Dummy>
622 using _ImplicitDefaultCtor = __enable_if_t<
623 _TCC<_Dummy>::__is_implicitly_default_constructible(),
624 bool>;
625
626 // Constraint for explicit default constructor
627 template<bool _Dummy>
628 using _ExplicitDefaultCtor = __enable_if_t<
629 _TCC<_Dummy>::__is_explicitly_default_constructible(),
630 bool>;
631
632 // Constraint for non-explicit constructors
633 template<bool _Cond, typename... _Args>
634 using _ImplicitCtor = __enable_if_t<
635 _TCC<_Cond>::template __is_implicitly_constructible<_Args...>(),
636 bool>;
637
638 // Constraint for non-explicit constructors
639 template<bool _Cond, typename... _Args>
640 using _ExplicitCtor = __enable_if_t<
641 _TCC<_Cond>::template __is_explicitly_constructible<_Args...>(),
642 bool>;
643
644 template<typename... _UElements>
645 static constexpr
646 __enable_if_t<sizeof...(_UElements) == sizeof...(_Elements), bool>
647 __assignable()
648 { return __and_<is_assignable<_Elements&, _UElements>...>::value; }
649
650 // Condition for noexcept-specifier of an assignment operator.
651 template<typename... _UElements>
652 static constexpr bool __nothrow_assignable()
653 {
654 return
655 __and_<is_nothrow_assignable<_Elements&, _UElements>...>::value;
656 }
657
658 // Condition for noexcept-specifier of a constructor.
659 template<typename... _UElements>
660 static constexpr bool __nothrow_constructible()
661 {
662 return
663 __and_<is_nothrow_constructible<_Elements, _UElements>...>::value;
664 }
665
666 // Constraint for tuple(_UTypes&&...) where sizeof...(_UTypes) == 1.
667 template<typename _Up>
668 static constexpr bool __valid_args()
669 {
670 return sizeof...(_Elements) == 1
671 && !is_same<tuple, __remove_cvref_t<_Up>>::value;
672 }
673
674 // Constraint for tuple(_UTypes&&...) where sizeof...(_UTypes) > 1.
675 template<typename, typename, typename... _Tail>
676 static constexpr bool __valid_args()
677 { return (sizeof...(_Tail) + 2) == sizeof...(_Elements); }
678
679 /* Constraint for constructors with a tuple<UTypes...> parameter ensures
680 * that the constructor is only viable when it would not interfere with
681 * tuple(UTypes&&...) or tuple(const tuple&) or tuple(tuple&&).
682 * Such constructors are only viable if:
683 * either sizeof...(Types) != 1,
684 * or (when Types... expands to T and UTypes... expands to U)
685 * is_convertible_v<TUPLE, T>, is_constructible_v<T, TUPLE>,
686 * and is_same_v<T, U> are all false.
687 */
688 template<typename _Tuple, typename = tuple,
689 typename = __remove_cvref_t<_Tuple>>
690 struct _UseOtherCtor
691 : false_type
692 { };
693 // If TUPLE is convertible to the single element in *this,
694 // then TUPLE should match tuple(UTypes&&...) instead.
695 template<typename _Tuple, typename _Tp, typename _Up>
696 struct _UseOtherCtor<_Tuple, tuple<_Tp>, tuple<_Up>>
697 : __or_<is_convertible<_Tuple, _Tp>, is_constructible<_Tp, _Tuple>>
698 { };
699 // If TUPLE and *this each have a single element of the same type,
700 // then TUPLE should match a copy/move constructor instead.
701 template<typename _Tuple, typename _Tp>
702 struct _UseOtherCtor<_Tuple, tuple<_Tp>, tuple<_Tp>>
703 : true_type
704 { };
705
706 // Return true iff sizeof...(Types) == 1 && tuple_size_v<TUPLE> == 1
707 // and the single element in Types can be initialized from TUPLE,
708 // or is the same type as tuple_element_t<0, TUPLE>.
709 template<typename _Tuple>
710 static constexpr bool __use_other_ctor()
711 { return _UseOtherCtor<_Tuple>::value; }
712
713 public:
714 template<typename _Dummy = void,
715 _ImplicitDefaultCtor<is_void<_Dummy>::value> = true>
716 constexpr
717 tuple()
718 noexcept(__and_<is_nothrow_default_constructible<_Elements>...>::value)
719 : _Inherited() { }
720
721 template<typename _Dummy = void,
722 _ExplicitDefaultCtor<is_void<_Dummy>::value> = false>
723 explicit constexpr
724 tuple()
725 noexcept(__and_<is_nothrow_default_constructible<_Elements>...>::value)
726 : _Inherited() { }
727
728 template<bool _NotEmpty = (sizeof...(_Elements) >= 1),
729 _ImplicitCtor<_NotEmpty, const _Elements&...> = true>
730 constexpr
731 tuple(const _Elements&... __elements)
732 noexcept(__nothrow_constructible<const _Elements&...>())
733 : _Inherited(__elements...) { }
734
735 template<bool _NotEmpty = (sizeof...(_Elements) >= 1),
736 _ExplicitCtor<_NotEmpty, const _Elements&...> = false>
737 explicit constexpr
738 tuple(const _Elements&... __elements)
739 noexcept(__nothrow_constructible<const _Elements&...>())
740 : _Inherited(__elements...) { }
741
742 template<typename... _UElements,
743 bool _Valid = __valid_args<_UElements...>(),
744 _ImplicitCtor<_Valid, _UElements...> = true>
745 constexpr
746 tuple(_UElements&&... __elements)
747 noexcept(__nothrow_constructible<_UElements...>())
748 : _Inherited(std::forward<_UElements>(__elements)...) { }
749
750 template<typename... _UElements,
751 bool _Valid = __valid_args<_UElements...>(),
752 _ExplicitCtor<_Valid, _UElements...> = false>
753 explicit constexpr
754 tuple(_UElements&&... __elements)
755 noexcept(__nothrow_constructible<_UElements...>())
756 : _Inherited(std::forward<_UElements>(__elements)...) { }
757
758 constexpr tuple(const tuple&) = default;
759
760 constexpr tuple(tuple&&) = default;
761
762 template<typename... _UElements,
763 bool _Valid = (sizeof...(_Elements) == sizeof...(_UElements))
764 && !__use_other_ctor<const tuple<_UElements...>&>(),
765 _ImplicitCtor<_Valid, const _UElements&...> = true>
766 constexpr
767 tuple(const tuple<_UElements...>& __in)
768 noexcept(__nothrow_constructible<const _UElements&...>())
769 : _Inherited(static_cast<const _Tuple_impl<0, _UElements...>&>(__in))
770 { }
771
772 template<typename... _UElements,
773 bool _Valid = (sizeof...(_Elements) == sizeof...(_UElements))
774 && !__use_other_ctor<const tuple<_UElements...>&>(),
775 _ExplicitCtor<_Valid, const _UElements&...> = false>
776 explicit constexpr
777 tuple(const tuple<_UElements...>& __in)
778 noexcept(__nothrow_constructible<const _UElements&...>())
779 : _Inherited(static_cast<const _Tuple_impl<0, _UElements...>&>(__in))
780 { }
781
782 template<typename... _UElements,
783 bool _Valid = (sizeof...(_Elements) == sizeof...(_UElements))
784 && !__use_other_ctor<tuple<_UElements...>&&>(),
785 _ImplicitCtor<_Valid, _UElements...> = true>
786 constexpr
787 tuple(tuple<_UElements...>&& __in)
788 noexcept(__nothrow_constructible<_UElements...>())
789 : _Inherited(static_cast<_Tuple_impl<0, _UElements...>&&>(__in)) { }
790
791 template<typename... _UElements,
792 bool _Valid = (sizeof...(_Elements) == sizeof...(_UElements))
793 && !__use_other_ctor<tuple<_UElements...>&&>(),
794 _ExplicitCtor<_Valid, _UElements...> = false>
795 explicit constexpr
796 tuple(tuple<_UElements...>&& __in)
797 noexcept(__nothrow_constructible<_UElements...>())
798 : _Inherited(static_cast<_Tuple_impl<0, _UElements...>&&>(__in)) { }
799
800 // Allocator-extended constructors.
801
802 template<typename _Alloc,
803 _ImplicitDefaultCtor<is_object<_Alloc>::value> = true>
804 _GLIBCXX20_CONSTEXPR
805 tuple(allocator_arg_t __tag, const _Alloc& __a)
806 : _Inherited(__tag, __a) { }
807
808 template<typename _Alloc, bool _NotEmpty = (sizeof...(_Elements) >= 1),
809 _ImplicitCtor<_NotEmpty, const _Elements&...> = true>
810 _GLIBCXX20_CONSTEXPR
811 tuple(allocator_arg_t __tag, const _Alloc& __a,
812 const _Elements&... __elements)
813 : _Inherited(__tag, __a, __elements...) { }
814
815 template<typename _Alloc, bool _NotEmpty = (sizeof...(_Elements) >= 1),
816 _ExplicitCtor<_NotEmpty, const _Elements&...> = false>
817 _GLIBCXX20_CONSTEXPR
818 explicit
819 tuple(allocator_arg_t __tag, const _Alloc& __a,
820 const _Elements&... __elements)
821 : _Inherited(__tag, __a, __elements...) { }
822
823 template<typename _Alloc, typename... _UElements,
824 bool _Valid = __valid_args<_UElements...>(),
825 _ImplicitCtor<_Valid, _UElements...> = true>
826 _GLIBCXX20_CONSTEXPR
827 tuple(allocator_arg_t __tag, const _Alloc& __a,
828 _UElements&&... __elements)
829 : _Inherited(__tag, __a, std::forward<_UElements>(__elements)...)
830 { }
831
832 template<typename _Alloc, typename... _UElements,
833 bool _Valid = __valid_args<_UElements...>(),
834 _ExplicitCtor<_Valid, _UElements...> = false>
835 _GLIBCXX20_CONSTEXPR
836 explicit
837 tuple(allocator_arg_t __tag, const _Alloc& __a,
838 _UElements&&... __elements)
839 : _Inherited(__tag, __a, std::forward<_UElements>(__elements)...)
840 { }
841
842 template<typename _Alloc>
843 _GLIBCXX20_CONSTEXPR
844 tuple(allocator_arg_t __tag, const _Alloc& __a, const tuple& __in)
845 : _Inherited(__tag, __a, static_cast<const _Inherited&>(__in)) { }
846
847 template<typename _Alloc>
848 _GLIBCXX20_CONSTEXPR
849 tuple(allocator_arg_t __tag, const _Alloc& __a, tuple&& __in)
850 : _Inherited(__tag, __a, static_cast<_Inherited&&>(__in)) { }
851
852 template<typename _Alloc, typename... _UElements,
853 bool _Valid = (sizeof...(_Elements) == sizeof...(_UElements))
854 && !__use_other_ctor<const tuple<_UElements...>&>(),
855 _ImplicitCtor<_Valid, const _UElements&...> = true>
856 _GLIBCXX20_CONSTEXPR
857 tuple(allocator_arg_t __tag, const _Alloc& __a,
858 const tuple<_UElements...>& __in)
859 : _Inherited(__tag, __a,
860 static_cast<const _Tuple_impl<0, _UElements...>&>(__in))
861 { }
862
863 template<typename _Alloc, typename... _UElements,
864 bool _Valid = (sizeof...(_Elements) == sizeof...(_UElements))
865 && !__use_other_ctor<const tuple<_UElements...>&>(),
866 _ExplicitCtor<_Valid, const _UElements&...> = false>
867 _GLIBCXX20_CONSTEXPR
868 explicit
869 tuple(allocator_arg_t __tag, const _Alloc& __a,
870 const tuple<_UElements...>& __in)
871 : _Inherited(__tag, __a,
872 static_cast<const _Tuple_impl<0, _UElements...>&>(__in))
873 { }
874
875 template<typename _Alloc, typename... _UElements,
876 bool _Valid = (sizeof...(_Elements) == sizeof...(_UElements))
877 && !__use_other_ctor<tuple<_UElements...>&&>(),
878 _ImplicitCtor<_Valid, _UElements...> = true>
879 _GLIBCXX20_CONSTEXPR
880 tuple(allocator_arg_t __tag, const _Alloc& __a,
881 tuple<_UElements...>&& __in)
882 : _Inherited(__tag, __a,
883 static_cast<_Tuple_impl<0, _UElements...>&&>(__in))
884 { }
885
886 template<typename _Alloc, typename... _UElements,
887 bool _Valid = (sizeof...(_Elements) == sizeof...(_UElements))
888 && !__use_other_ctor<tuple<_UElements...>&&>(),
889 _ExplicitCtor<_Valid, _UElements...> = false>
890 _GLIBCXX20_CONSTEXPR
891 explicit
892 tuple(allocator_arg_t __tag, const _Alloc& __a,
893 tuple<_UElements...>&& __in)
894 : _Inherited(__tag, __a,
895 static_cast<_Tuple_impl<0, _UElements...>&&>(__in))
896 { }
897
898 // tuple assignment
899
900 _GLIBCXX20_CONSTEXPR
901 tuple&
902 operator=(typename conditional<__assignable<const _Elements&...>(),
903 const tuple&,
904 const __nonesuch&>::type __in)
905 noexcept(__nothrow_assignable<const _Elements&...>())
906 {
907 this->_M_assign(__in);
908 return *this;
909 }
910
911 _GLIBCXX20_CONSTEXPR
912 tuple&
913 operator=(typename conditional<__assignable<_Elements...>(),
914 tuple&&,
915 __nonesuch&&>::type __in)
916 noexcept(__nothrow_assignable<_Elements...>())
917 {
918 this->_M_assign(std::move(__in));
919 return *this;
920 }
921
922 template<typename... _UElements>
923 _GLIBCXX20_CONSTEXPR
924 __enable_if_t<__assignable<const _UElements&...>(), tuple&>
925 operator=(const tuple<_UElements...>& __in)
926 noexcept(__nothrow_assignable<const _UElements&...>())
927 {
928 this->_M_assign(__in);
929 return *this;
930 }
931
932 template<typename... _UElements>
933 _GLIBCXX20_CONSTEXPR
934 __enable_if_t<__assignable<_UElements...>(), tuple&>
935 operator=(tuple<_UElements...>&& __in)
936 noexcept(__nothrow_assignable<_UElements...>())
937 {
938 this->_M_assign(std::move(__in));
939 return *this;
940 }
941
942 // tuple swap
943 _GLIBCXX20_CONSTEXPR
944 void
945 swap(tuple& __in)
946 noexcept(__and_<__is_nothrow_swappable<_Elements>...>::value)
947 { _Inherited::_M_swap(__in); }
948 };
949
950#if __cpp_deduction_guides >= 201606
951 template<typename... _UTypes>
952 tuple(_UTypes...) -> tuple<_UTypes...>;
953 template<typename _T1, typename _T2>
954 tuple(pair<_T1, _T2>) -> tuple<_T1, _T2>;
955 template<typename _Alloc, typename... _UTypes>
956 tuple(allocator_arg_t, _Alloc, _UTypes...) -> tuple<_UTypes...>;
957 template<typename _Alloc, typename _T1, typename _T2>
958 tuple(allocator_arg_t, _Alloc, pair<_T1, _T2>) -> tuple<_T1, _T2>;
959 template<typename _Alloc, typename... _UTypes>
960 tuple(allocator_arg_t, _Alloc, tuple<_UTypes...>) -> tuple<_UTypes...>;
961#endif
962
963 // Explicit specialization, zero-element tuple.
964 template<>
965 class tuple<>
966 {
967 public:
968 _GLIBCXX20_CONSTEXPR
969 void swap(tuple&) noexcept { /* no-op */ }
970 // We need the default since we're going to define no-op
971 // allocator constructors.
972 tuple() = default;
973 // No-op allocator constructors.
974 template<typename _Alloc>
975 _GLIBCXX20_CONSTEXPR
976 tuple(allocator_arg_t, const _Alloc&) noexcept { }
977 template<typename _Alloc>
978 _GLIBCXX20_CONSTEXPR
979 tuple(allocator_arg_t, const _Alloc&, const tuple&) noexcept { }
980 };
981
982 /// Partial specialization, 2-element tuple.
983 /// Includes construction and assignment from a pair.
984 template<typename _T1, typename _T2>
985 class tuple<_T1, _T2> : public _Tuple_impl<0, _T1, _T2>
986 {
987 typedef _Tuple_impl<0, _T1, _T2> _Inherited;
988
989 // Constraint for non-explicit default constructor
990 template<bool _Dummy, typename _U1, typename _U2>
991 using _ImplicitDefaultCtor = __enable_if_t<
992 _TupleConstraints<_Dummy, _U1, _U2>::
993 __is_implicitly_default_constructible(),
994 bool>;
995
996 // Constraint for explicit default constructor
997 template<bool _Dummy, typename _U1, typename _U2>
998 using _ExplicitDefaultCtor = __enable_if_t<
999 _TupleConstraints<_Dummy, _U1, _U2>::
1000 __is_explicitly_default_constructible(),
1001 bool>;
1002
1003 template<bool _Dummy>
1004 using _TCC = _TupleConstraints<_Dummy, _T1, _T2>;
1005
1006 // Constraint for non-explicit constructors
1007 template<bool _Cond, typename _U1, typename _U2>
1008 using _ImplicitCtor = __enable_if_t<
1009 _TCC<_Cond>::template __is_implicitly_constructible<_U1, _U2>(),
1010 bool>;
1011
1012 // Constraint for non-explicit constructors
1013 template<bool _Cond, typename _U1, typename _U2>
1014 using _ExplicitCtor = __enable_if_t<
1015 _TCC<_Cond>::template __is_explicitly_constructible<_U1, _U2>(),
1016 bool>;
1017
1018 template<typename _U1, typename _U2>
1019 static constexpr bool __assignable()
1020 {
1021 return __and_<is_assignable<_T1&, _U1>,
1022 is_assignable<_T2&, _U2>>::value;
1023 }
1024
1025 template<typename _U1, typename _U2>
1026 static constexpr bool __nothrow_assignable()
1027 {
1028 return __and_<is_nothrow_assignable<_T1&, _U1>,
1029 is_nothrow_assignable<_T2&, _U2>>::value;
1030 }
1031
1032 template<typename _U1, typename _U2>
1033 static constexpr bool __nothrow_constructible()
1034 {
1035 return __and_<is_nothrow_constructible<_T1, _U1>,
1036 is_nothrow_constructible<_T2, _U2>>::value;
1037 }
1038
1039 static constexpr bool __nothrow_default_constructible()
1040 {
1041 return __and_<is_nothrow_default_constructible<_T1>,
1042 is_nothrow_default_constructible<_T2>>::value;
1043 }
1044
1045 template<typename _U1>
1046 static constexpr bool __is_alloc_arg()
1047 { return is_same<__remove_cvref_t<_U1>, allocator_arg_t>::value; }
1048
1049 public:
1050 template<bool _Dummy = true,
1051 _ImplicitDefaultCtor<_Dummy, _T1, _T2> = true>
1052 constexpr
1053 tuple()
1054 noexcept(__nothrow_default_constructible())
1055 : _Inherited() { }
1056
1057 template<bool _Dummy = true,
1058 _ExplicitDefaultCtor<_Dummy, _T1, _T2> = false>
1059 explicit constexpr
1060 tuple()
1061 noexcept(__nothrow_default_constructible())
1062 : _Inherited() { }
1063
1064 template<bool _Dummy = true,
1065 _ImplicitCtor<_Dummy, const _T1&, const _T2&> = true>
1066 constexpr
1067 tuple(const _T1& __a1, const _T2& __a2)
1068 noexcept(__nothrow_constructible<const _T1&, const _T2&>())
1069 : _Inherited(__a1, __a2) { }
1070
1071 template<bool _Dummy = true,
1072 _ExplicitCtor<_Dummy, const _T1&, const _T2&> = false>
1073 explicit constexpr
1074 tuple(const _T1& __a1, const _T2& __a2)
1075 noexcept(__nothrow_constructible<const _T1&, const _T2&>())
1076 : _Inherited(__a1, __a2) { }
1077
1078 template<typename _U1, typename _U2,
1079 _ImplicitCtor<!__is_alloc_arg<_U1>(), _U1, _U2> = true>
1080 constexpr
1081 tuple(_U1&& __a1, _U2&& __a2)
1082 noexcept(__nothrow_constructible<_U1, _U2>())
1083 : _Inherited(std::forward<_U1>(__a1), std::forward<_U2>(__a2)) { }
1084
1085 template<typename _U1, typename _U2,
1086 _ExplicitCtor<!__is_alloc_arg<_U1>(), _U1, _U2> = false>
1087 explicit constexpr
1088 tuple(_U1&& __a1, _U2&& __a2)
1089 noexcept(__nothrow_constructible<_U1, _U2>())
1090 : _Inherited(std::forward<_U1>(__a1), std::forward<_U2>(__a2)) { }
1091
1092 constexpr tuple(const tuple&) = default;
1093
1094 constexpr tuple(tuple&&) = default;
1095
1096 template<typename _U1, typename _U2,
1097 _ImplicitCtor<true, const _U1&, const _U2&> = true>
1098 constexpr
1099 tuple(const tuple<_U1, _U2>& __in)
1100 noexcept(__nothrow_constructible<const _U1&, const _U2&>())
1101 : _Inherited(static_cast<const _Tuple_impl<0, _U1, _U2>&>(__in)) { }
1102
1103 template<typename _U1, typename _U2,
1104 _ExplicitCtor<true, const _U1&, const _U2&> = false>
1105 explicit constexpr
1106 tuple(const tuple<_U1, _U2>& __in)
1107 noexcept(__nothrow_constructible<const _U1&, const _U2&>())
1108 : _Inherited(static_cast<const _Tuple_impl<0, _U1, _U2>&>(__in)) { }
1109
1110 template<typename _U1, typename _U2,
1111 _ImplicitCtor<true, _U1, _U2> = true>
1112 constexpr
1113 tuple(tuple<_U1, _U2>&& __in)
1114 noexcept(__nothrow_constructible<_U1, _U2>())
1115 : _Inherited(static_cast<_Tuple_impl<0, _U1, _U2>&&>(__in)) { }
1116
1117 template<typename _U1, typename _U2,
1118 _ExplicitCtor<true, _U1, _U2> = false>
1119 explicit constexpr
1120 tuple(tuple<_U1, _U2>&& __in)
1121 noexcept(__nothrow_constructible<_U1, _U2>())
1122 : _Inherited(static_cast<_Tuple_impl<0, _U1, _U2>&&>(__in)) { }
1123
1124 template<typename _U1, typename _U2,
1125 _ImplicitCtor<true, const _U1&, const _U2&> = true>
1126 constexpr
1127 tuple(const pair<_U1, _U2>& __in)
1128 noexcept(__nothrow_constructible<const _U1&, const _U2&>())
1129 : _Inherited(__in.first, __in.second) { }
1130
1131 template<typename _U1, typename _U2,
1132 _ExplicitCtor<true, const _U1&, const _U2&> = false>
1133 explicit constexpr
1134 tuple(const pair<_U1, _U2>& __in)
1135 noexcept(__nothrow_constructible<const _U1&, const _U2&>())
1136 : _Inherited(__in.first, __in.second) { }
1137
1138 template<typename _U1, typename _U2,
1139 _ImplicitCtor<true, _U1, _U2> = true>
1140 constexpr
1141 tuple(pair<_U1, _U2>&& __in)
1142 noexcept(__nothrow_constructible<_U1, _U2>())
1143 : _Inherited(std::forward<_U1>(__in.first),
1144 std::forward<_U2>(__in.second)) { }
1145
1146 template<typename _U1, typename _U2,
1147 _ExplicitCtor<true, _U1, _U2> = false>
1148 explicit constexpr
1149 tuple(pair<_U1, _U2>&& __in)
1150 noexcept(__nothrow_constructible<_U1, _U2>())
1151 : _Inherited(std::forward<_U1>(__in.first),
1152 std::forward<_U2>(__in.second)) { }
1153
1154 // Allocator-extended constructors.
1155
1156 template<typename _Alloc,
1157 _ImplicitDefaultCtor<is_object<_Alloc>::value, _T1, _T2> = true>
1158 _GLIBCXX20_CONSTEXPR
1159 tuple(allocator_arg_t __tag, const _Alloc& __a)
1160 : _Inherited(__tag, __a) { }
1161
1162 template<typename _Alloc, bool _Dummy = true,
1163 _ImplicitCtor<_Dummy, const _T1&, const _T2&> = true>
1164 _GLIBCXX20_CONSTEXPR
1165 tuple(allocator_arg_t __tag, const _Alloc& __a,
1166 const _T1& __a1, const _T2& __a2)
1167 : _Inherited(__tag, __a, __a1, __a2) { }
1168
1169 template<typename _Alloc, bool _Dummy = true,
1170 _ExplicitCtor<_Dummy, const _T1&, const _T2&> = false>
1171 explicit
1172 _GLIBCXX20_CONSTEXPR
1173 tuple(allocator_arg_t __tag, const _Alloc& __a,
1174 const _T1& __a1, const _T2& __a2)
1175 : _Inherited(__tag, __a, __a1, __a2) { }
1176
1177 template<typename _Alloc, typename _U1, typename _U2,
1178 _ImplicitCtor<true, _U1, _U2> = true>
1179 _GLIBCXX20_CONSTEXPR
1180 tuple(allocator_arg_t __tag, const _Alloc& __a, _U1&& __a1, _U2&& __a2)
1181 : _Inherited(__tag, __a, std::forward<_U1>(__a1),
1182 std::forward<_U2>(__a2)) { }
1183
1184 template<typename _Alloc, typename _U1, typename _U2,
1185 _ExplicitCtor<true, _U1, _U2> = false>
1186 explicit
1187 _GLIBCXX20_CONSTEXPR
1188 tuple(allocator_arg_t __tag, const _Alloc& __a,
1189 _U1&& __a1, _U2&& __a2)
1190 : _Inherited(__tag, __a, std::forward<_U1>(__a1),
1191 std::forward<_U2>(__a2)) { }
1192
1193 template<typename _Alloc>
1194 _GLIBCXX20_CONSTEXPR
1195 tuple(allocator_arg_t __tag, const _Alloc& __a, const tuple& __in)
1196 : _Inherited(__tag, __a, static_cast<const _Inherited&>(__in)) { }
1197
1198 template<typename _Alloc>
1199 _GLIBCXX20_CONSTEXPR
1200 tuple(allocator_arg_t __tag, const _Alloc& __a, tuple&& __in)
1201 : _Inherited(__tag, __a, static_cast<_Inherited&&>(__in)) { }
1202
1203 template<typename _Alloc, typename _U1, typename _U2,
1204 _ImplicitCtor<true, const _U1&, const _U2&> = true>
1205 _GLIBCXX20_CONSTEXPR
1206 tuple(allocator_arg_t __tag, const _Alloc& __a,
1207 const tuple<_U1, _U2>& __in)
1208 : _Inherited(__tag, __a,
1209 static_cast<const _Tuple_impl<0, _U1, _U2>&>(__in))
1210 { }
1211
1212 template<typename _Alloc, typename _U1, typename _U2,
1213 _ExplicitCtor<true, const _U1&, const _U2&> = false>
1214 explicit
1215 _GLIBCXX20_CONSTEXPR
1216 tuple(allocator_arg_t __tag, const _Alloc& __a,
1217 const tuple<_U1, _U2>& __in)
1218 : _Inherited(__tag, __a,
1219 static_cast<const _Tuple_impl<0, _U1, _U2>&>(__in))
1220 { }
1221
1222 template<typename _Alloc, typename _U1, typename _U2,
1223 _ImplicitCtor<true, _U1, _U2> = true>
1224 _GLIBCXX20_CONSTEXPR
1225 tuple(allocator_arg_t __tag, const _Alloc& __a, tuple<_U1, _U2>&& __in)
1226 : _Inherited(__tag, __a, static_cast<_Tuple_impl<0, _U1, _U2>&&>(__in))
1227 { }
1228
1229 template<typename _Alloc, typename _U1, typename _U2,
1230 _ExplicitCtor<true, _U1, _U2> = false>
1231 explicit
1232 _GLIBCXX20_CONSTEXPR
1233 tuple(allocator_arg_t __tag, const _Alloc& __a, tuple<_U1, _U2>&& __in)
1234 : _Inherited(__tag, __a, static_cast<_Tuple_impl<0, _U1, _U2>&&>(__in))
1235 { }
1236
1237 template<typename _Alloc, typename _U1, typename _U2,
1238 _ImplicitCtor<true, const _U1&, const _U2&> = true>
1239 _GLIBCXX20_CONSTEXPR
1240 tuple(allocator_arg_t __tag, const _Alloc& __a,
1241 const pair<_U1, _U2>& __in)
1242 : _Inherited(__tag, __a, __in.first, __in.second) { }
1243
1244 template<typename _Alloc, typename _U1, typename _U2,
1245 _ExplicitCtor<true, const _U1&, const _U2&> = false>
1246 explicit
1247 _GLIBCXX20_CONSTEXPR
1248 tuple(allocator_arg_t __tag, const _Alloc& __a,
1249 const pair<_U1, _U2>& __in)
1250 : _Inherited(__tag, __a, __in.first, __in.second) { }
1251
1252 template<typename _Alloc, typename _U1, typename _U2,
1253 _ImplicitCtor<true, _U1, _U2> = true>
1254 _GLIBCXX20_CONSTEXPR
1255 tuple(allocator_arg_t __tag, const _Alloc& __a, pair<_U1, _U2>&& __in)
1256 : _Inherited(__tag, __a, std::forward<_U1>(__in.first),
1257 std::forward<_U2>(__in.second)) { }
1258
1259 template<typename _Alloc, typename _U1, typename _U2,
1260 _ExplicitCtor<true, _U1, _U2> = false>
1261 explicit
1262 _GLIBCXX20_CONSTEXPR
1263 tuple(allocator_arg_t __tag, const _Alloc& __a, pair<_U1, _U2>&& __in)
1264 : _Inherited(__tag, __a, std::forward<_U1>(__in.first),
1265 std::forward<_U2>(__in.second)) { }
1266
1267 // Tuple assignment.
1268
1269 _GLIBCXX20_CONSTEXPR
1270 tuple&
1271 operator=(typename conditional<__assignable<const _T1&, const _T2&>(),
1272 const tuple&,
1273 const __nonesuch&>::type __in)
1274 noexcept(__nothrow_assignable<const _T1&, const _T2&>())
1275 {
1276 this->_M_assign(__in);
1277 return *this;
1278 }
1279
1280 _GLIBCXX20_CONSTEXPR
1281 tuple&
1282 operator=(typename conditional<__assignable<_T1, _T2>(),
1283 tuple&&,
1284 __nonesuch&&>::type __in)
1285 noexcept(__nothrow_assignable<_T1, _T2>())
1286 {
1287 this->_M_assign(std::move(__in));
1288 return *this;
1289 }
1290
1291 template<typename _U1, typename _U2>
1292 _GLIBCXX20_CONSTEXPR
1293 __enable_if_t<__assignable<const _U1&, const _U2&>(), tuple&>
1294 operator=(const tuple<_U1, _U2>& __in)
1295 noexcept(__nothrow_assignable<const _U1&, const _U2&>())
1296 {
1297 this->_M_assign(__in);
1298 return *this;
1299 }
1300
1301 template<typename _U1, typename _U2>
1302 _GLIBCXX20_CONSTEXPR
1303 __enable_if_t<__assignable<_U1, _U2>(), tuple&>
1304 operator=(tuple<_U1, _U2>&& __in)
1305 noexcept(__nothrow_assignable<_U1, _U2>())
1306 {
1307 this->_M_assign(std::move(__in));
1308 return *this;
1309 }
1310
1311 template<typename _U1, typename _U2>
1312 _GLIBCXX20_CONSTEXPR
1313 __enable_if_t<__assignable<const _U1&, const _U2&>(), tuple&>
1314 operator=(const pair<_U1, _U2>& __in)
1315 noexcept(__nothrow_assignable<const _U1&, const _U2&>())
1316 {
1317 this->_M_head(*this) = __in.first;
1318 this->_M_tail(*this)._M_head(*this) = __in.second;
1319 return *this;
1320 }
1321
1322 template<typename _U1, typename _U2>
1323 _GLIBCXX20_CONSTEXPR
1324 __enable_if_t<__assignable<_U1, _U2>(), tuple&>
1325 operator=(pair<_U1, _U2>&& __in)
1326 noexcept(__nothrow_assignable<_U1, _U2>())
1327 {
1328 this->_M_head(*this) = std::forward<_U1>(__in.first);
1329 this->_M_tail(*this)._M_head(*this) = std::forward<_U2>(__in.second);
1330 return *this;
1331 }
1332
1333 _GLIBCXX20_CONSTEXPR
1334 void
1335 swap(tuple& __in)
1336 noexcept(__and_<__is_nothrow_swappable<_T1>,
1337 __is_nothrow_swappable<_T2>>::value)
1338 { _Inherited::_M_swap(__in); }
1339 };
1340
1341
1342 /// class tuple_size
1343 template<typename... _Elements>
1344 struct tuple_size<tuple<_Elements...>>
1345 : public integral_constant<size_t, sizeof...(_Elements)> { };
1346
1347#if __cplusplus > 201402L
1348 template <typename _Tp>
1349 inline constexpr size_t tuple_size_v = tuple_size<_Tp>::value;
1350#endif
1351
1352 /**
1353 * Recursive case for tuple_element: strip off the first element in
1354 * the tuple and retrieve the (i-1)th element of the remaining tuple.
1355 */
1356 template<size_t __i, typename _Head, typename... _Tail>
1357 struct tuple_element<__i, tuple<_Head, _Tail...> >
1358 : tuple_element<__i - 1, tuple<_Tail...> > { };
1359
1360 /**
1361 * Basis case for tuple_element: The first element is the one we're seeking.
1362 */
1363 template<typename _Head, typename... _Tail>
1364 struct tuple_element<0, tuple<_Head, _Tail...> >
1365 {
1366 typedef _Head type;
1367 };
1368
1369 /**
1370 * Error case for tuple_element: invalid index.
1371 */
1372 template<size_t __i>
1373 struct tuple_element<__i, tuple<>>
1374 {
1375 static_assert(__i < tuple_size<tuple<>>::value,
1376 "tuple index must be in range");
1377 };
1378
1379 template<size_t __i, typename _Head, typename... _Tail>
1380 constexpr _Head&
1381 __get_helper(_Tuple_impl<__i, _Head, _Tail...>& __t) noexcept
1382 { return _Tuple_impl<__i, _Head, _Tail...>::_M_head(__t); }
1383
1384 template<size_t __i, typename _Head, typename... _Tail>
1385 constexpr const _Head&
1386 __get_helper(const _Tuple_impl<__i, _Head, _Tail...>& __t) noexcept
1387 { return _Tuple_impl<__i, _Head, _Tail...>::_M_head(__t); }
1388
1389 // Deleted overload to improve diagnostics for invalid indices
1390 template<size_t __i, typename... _Types>
1391 __enable_if_t<(__i >= sizeof...(_Types))>
1392 __get_helper(const tuple<_Types...>&) = delete;
1393
1394 /// Return a reference to the ith element of a tuple.
1395 template<size_t __i, typename... _Elements>
1396 constexpr __tuple_element_t<__i, tuple<_Elements...>>&
1397 get(tuple<_Elements...>& __t) noexcept
1398 { return std::__get_helper<__i>(__t); }
1399
1400 /// Return a const reference to the ith element of a const tuple.
1401 template<size_t __i, typename... _Elements>
1402 constexpr const __tuple_element_t<__i, tuple<_Elements...>>&
1403 get(const tuple<_Elements...>& __t) noexcept
1404 { return std::__get_helper<__i>(__t); }
1405
1406 /// Return an rvalue reference to the ith element of a tuple rvalue.
1407 template<size_t __i, typename... _Elements>
1408 constexpr __tuple_element_t<__i, tuple<_Elements...>>&&
1409 get(tuple<_Elements...>&& __t) noexcept
1410 {
1411 typedef __tuple_element_t<__i, tuple<_Elements...>> __element_type;
1412 return std::forward<__element_type>(std::__get_helper<__i>(__t));
1413 }
1414
1415 /// Return a const rvalue reference to the ith element of a const tuple rvalue.
1416 template<size_t __i, typename... _Elements>
1417 constexpr const __tuple_element_t<__i, tuple<_Elements...>>&&
1418 get(const tuple<_Elements...>&& __t) noexcept
1419 {
1420 typedef __tuple_element_t<__i, tuple<_Elements...>> __element_type;
1421 return std::forward<const __element_type>(std::__get_helper<__i>(__t));
1422 }
1423
1424#if __cplusplus >= 201402L
1425
1426#define __cpp_lib_tuples_by_type 201304
1427
1428 // Return the index of _Tp in _Types, if it occurs exactly once.
1429 // Otherwise, return sizeof...(_Types).
1430 // TODO reuse this for __detail::__variant::__exactly_once.
1431 template<typename _Tp, typename... _Types>
1432 constexpr size_t
1433 __find_uniq_type_in_pack()
1434 {
1435 constexpr size_t __sz = sizeof...(_Types);
1436 constexpr bool __found[__sz] = { __is_same(_Tp, _Types) ... };
1437 size_t __n = __sz;
1438 for (size_t __i = 0; __i < __sz; ++__i)
1439 {
1440 if (__found[__i])
1441 {
1442 if (__n < __sz) // more than one _Tp found
1443 return __sz;
1444 __n = __i;
1445 }
1446 }
1447 return __n;
1448 }
1449
1450 /// Return a reference to the unique element of type _Tp of a tuple.
1451 template <typename _Tp, typename... _Types>
1452 constexpr _Tp&
1453 get(tuple<_Types...>& __t) noexcept
1454 {
1455 constexpr size_t __idx = __find_uniq_type_in_pack<_Tp, _Types...>();
1456 static_assert(__idx < sizeof...(_Types),
1457 "the type T in std::get<T> must occur exactly once in the tuple");
1458 return std::__get_helper<__idx>(__t);
1459 }
1460
1461 /// Return a reference to the unique element of type _Tp of a tuple rvalue.
1462 template <typename _Tp, typename... _Types>
1463 constexpr _Tp&&
1464 get(tuple<_Types...>&& __t) noexcept
1465 {
1466 constexpr size_t __idx = __find_uniq_type_in_pack<_Tp, _Types...>();
1467 static_assert(__idx < sizeof...(_Types),
1468 "the type T in std::get<T> must occur exactly once in the tuple");
1469 return std::forward<_Tp>(std::__get_helper<__idx>(__t));
1470 }
1471
1472 /// Return a const reference to the unique element of type _Tp of a tuple.
1473 template <typename _Tp, typename... _Types>
1474 constexpr const _Tp&
1475 get(const tuple<_Types...>& __t) noexcept
1476 {
1477 constexpr size_t __idx = __find_uniq_type_in_pack<_Tp, _Types...>();
1478 static_assert(__idx < sizeof...(_Types),
1479 "the type T in std::get<T> must occur exactly once in the tuple");
1480 return std::__get_helper<__idx>(__t);
1481 }
1482
1483 /// Return a const reference to the unique element of type _Tp of
1484 /// a const tuple rvalue.
1485 template <typename _Tp, typename... _Types>
1486 constexpr const _Tp&&
1487 get(const tuple<_Types...>&& __t) noexcept
1488 {
1489 constexpr size_t __idx = __find_uniq_type_in_pack<_Tp, _Types...>();
1490 static_assert(__idx < sizeof...(_Types),
1491 "the type T in std::get<T> must occur exactly once in the tuple");
1492 return std::forward<const _Tp>(std::__get_helper<__idx>(__t));
1493 }
1494#endif
1495
1496 // This class performs the comparison operations on tuples
1497 template<typename _Tp, typename _Up, size_t __i, size_t __size>
1498 struct __tuple_compare
1499 {
1500 static constexpr bool
1501 __eq(const _Tp& __t, const _Up& __u)
1502 {
1503 return bool(std::get<__i>(__t) == std::get<__i>(__u))
1504 && __tuple_compare<_Tp, _Up, __i + 1, __size>::__eq(__t, __u);
1505 }
1506
1507 static constexpr bool
1508 __less(const _Tp& __t, const _Up& __u)
1509 {
1510 return bool(std::get<__i>(__t) < std::get<__i>(__u))
1511 || (!bool(std::get<__i>(__u) < std::get<__i>(__t))
1512 && __tuple_compare<_Tp, _Up, __i + 1, __size>::__less(__t, __u));
1513 }
1514 };
1515
1516 template<typename _Tp, typename _Up, size_t __size>
1517 struct __tuple_compare<_Tp, _Up, __size, __size>
1518 {
1519 static constexpr bool
1520 __eq(const _Tp&, const _Up&) { return true; }
1521
1522 static constexpr bool
1523 __less(const _Tp&, const _Up&) { return false; }
1524 };
1525
1526 template<typename... _TElements, typename... _UElements>
1527 constexpr bool
1528 operator==(const tuple<_TElements...>& __t,
1529 const tuple<_UElements...>& __u)
1530 {
1531 static_assert(sizeof...(_TElements) == sizeof...(_UElements),
1532 "tuple objects can only be compared if they have equal sizes.");
1533 using __compare = __tuple_compare<tuple<_TElements...>,
1534 tuple<_UElements...>,
1535 0, sizeof...(_TElements)>;
1536 return __compare::__eq(__t, __u);
1537 }
1538
1539#if __cpp_lib_three_way_comparison
1540 template<typename _Cat, typename _Tp, typename _Up>
1541 constexpr _Cat
1542 __tuple_cmp(const _Tp&, const _Up&, index_sequence<>)
1543 { return _Cat::equivalent; }
1544
1545 template<typename _Cat, typename _Tp, typename _Up,
1546 size_t _Idx0, size_t... _Idxs>
1547 constexpr _Cat
1548 __tuple_cmp(const _Tp& __t, const _Up& __u,
1549 index_sequence<_Idx0, _Idxs...>)
1550 {
1551 auto __c
1552 = __detail::__synth3way(std::get<_Idx0>(__t), std::get<_Idx0>(__u));
1553 if (__c != 0)
1554 return __c;
1555 return std::__tuple_cmp<_Cat>(__t, __u, index_sequence<_Idxs...>());
1556 }
1557
1558 template<typename... _Tps, typename... _Ups>
1559 constexpr
1560 common_comparison_category_t<__detail::__synth3way_t<_Tps, _Ups>...>
1561 operator<=>(const tuple<_Tps...>& __t, const tuple<_Ups...>& __u)
1562 {
1563 using _Cat
1564 = common_comparison_category_t<__detail::__synth3way_t<_Tps, _Ups>...>;
1565 return std::__tuple_cmp<_Cat>(__t, __u, index_sequence_for<_Tps...>());
1566 }
1567#else
1568 template<typename... _TElements, typename... _UElements>
1569 constexpr bool
1570 operator<(const tuple<_TElements...>& __t,
1571 const tuple<_UElements...>& __u)
1572 {
1573 static_assert(sizeof...(_TElements) == sizeof...(_UElements),
1574 "tuple objects can only be compared if they have equal sizes.");
1575 using __compare = __tuple_compare<tuple<_TElements...>,
1576 tuple<_UElements...>,
1577 0, sizeof...(_TElements)>;
1578 return __compare::__less(__t, __u);
1579 }
1580
1581 template<typename... _TElements, typename... _UElements>
1582 constexpr bool
1583 operator!=(const tuple<_TElements...>& __t,
1584 const tuple<_UElements...>& __u)
1585 { return !(__t == __u); }
1586
1587 template<typename... _TElements, typename... _UElements>
1588 constexpr bool
1589 operator>(const tuple<_TElements...>& __t,
1590 const tuple<_UElements...>& __u)
1591 { return __u < __t; }
1592
1593 template<typename... _TElements, typename... _UElements>
1594 constexpr bool
1595 operator<=(const tuple<_TElements...>& __t,
1596 const tuple<_UElements...>& __u)
1597 { return !(__u < __t); }
1598
1599 template<typename... _TElements, typename... _UElements>
1600 constexpr bool
1601 operator>=(const tuple<_TElements...>& __t,
1602 const tuple<_UElements...>& __u)
1603 { return !(__t < __u); }
1604#endif // three_way_comparison
1605
1606 // NB: DR 705.
1607 template<typename... _Elements>
1608 constexpr tuple<typename __decay_and_strip<_Elements>::__type...>
1609 make_tuple(_Elements&&... __args)
1610 {
1611 typedef tuple<typename __decay_and_strip<_Elements>::__type...>
1612 __result_type;
1613 return __result_type(std::forward<_Elements>(__args)...);
1614 }
1615
1616 // _GLIBCXX_RESOLVE_LIB_DEFECTS
1617 // 2275. Why is forward_as_tuple not constexpr?
1618 /// std::forward_as_tuple
1619 template<typename... _Elements>
1620 constexpr tuple<_Elements&&...>
1621 forward_as_tuple(_Elements&&... __args) noexcept
1622 { return tuple<_Elements&&...>(std::forward<_Elements>(__args)...); }
1623
1624 template<size_t, typename, typename, size_t>
1625 struct __make_tuple_impl;
1626
1627 template<size_t _Idx, typename _Tuple, typename... _Tp, size_t _Nm>
1628 struct __make_tuple_impl<_Idx, tuple<_Tp...>, _Tuple, _Nm>
1629 : __make_tuple_impl<_Idx + 1,
1630 tuple<_Tp..., __tuple_element_t<_Idx, _Tuple>>,
1631 _Tuple, _Nm>
1632 { };
1633
1634 template<size_t _Nm, typename _Tuple, typename... _Tp>
1635 struct __make_tuple_impl<_Nm, tuple<_Tp...>, _Tuple, _Nm>
1636 {
1637 typedef tuple<_Tp...> __type;
1638 };
1639
1640 template<typename _Tuple>
1641 struct __do_make_tuple
1642 : __make_tuple_impl<0, tuple<>, _Tuple, tuple_size<_Tuple>::value>
1643 { };
1644
1645 // Returns the std::tuple equivalent of a tuple-like type.
1646 template<typename _Tuple>
1647 struct __make_tuple
1648 : public __do_make_tuple<__remove_cvref_t<_Tuple>>
1649 { };
1650
1651 // Combines several std::tuple's into a single one.
1652 template<typename...>
1653 struct __combine_tuples;
1654
1655 template<>
1656 struct __combine_tuples<>
1657 {
1658 typedef tuple<> __type;
1659 };
1660
1661 template<typename... _Ts>
1662 struct __combine_tuples<tuple<_Ts...>>
1663 {
1664 typedef tuple<_Ts...> __type;
1665 };
1666
1667 template<typename... _T1s, typename... _T2s, typename... _Rem>
1668 struct __combine_tuples<tuple<_T1s...>, tuple<_T2s...>, _Rem...>
1669 {
1670 typedef typename __combine_tuples<tuple<_T1s..., _T2s...>,
1671 _Rem...>::__type __type;
1672 };
1673
1674 // Computes the result type of tuple_cat given a set of tuple-like types.
1675 template<typename... _Tpls>
1676 struct __tuple_cat_result
1677 {
1678 typedef typename __combine_tuples
1679 <typename __make_tuple<_Tpls>::__type...>::__type __type;
1680 };
1681
1682 // Helper to determine the index set for the first tuple-like
1683 // type of a given set.
1684 template<typename...>
1685 struct __make_1st_indices;
1686
1687 template<>
1688 struct __make_1st_indices<>
1689 {
1690 typedef _Index_tuple<> __type;
1691 };
1692
1693 template<typename _Tp, typename... _Tpls>
1694 struct __make_1st_indices<_Tp, _Tpls...>
1695 {
1696 typedef typename _Build_index_tuple<tuple_size<
1697 typename remove_reference<_Tp>::type>::value>::__type __type;
1698 };
1699
1700 // Performs the actual concatenation by step-wise expanding tuple-like
1701 // objects into the elements, which are finally forwarded into the
1702 // result tuple.
1703 template<typename _Ret, typename _Indices, typename... _Tpls>
1704 struct __tuple_concater;
1705
1706 template<typename _Ret, size_t... _Is, typename _Tp, typename... _Tpls>
1707 struct __tuple_concater<_Ret, _Index_tuple<_Is...>, _Tp, _Tpls...>
1708 {
1709 template<typename... _Us>
1710 static constexpr _Ret
1711 _S_do(_Tp&& __tp, _Tpls&&... __tps, _Us&&... __us)
1712 {
1713 typedef typename __make_1st_indices<_Tpls...>::__type __idx;
1714 typedef __tuple_concater<_Ret, __idx, _Tpls...> __next;
1715 return __next::_S_do(std::forward<_Tpls>(__tps)...,
1716 std::forward<_Us>(__us)...,
1717 std::get<_Is>(std::forward<_Tp>(__tp))...);
1718 }
1719 };
1720
1721 template<typename _Ret>
1722 struct __tuple_concater<_Ret, _Index_tuple<>>
1723 {
1724 template<typename... _Us>
1725 static constexpr _Ret
1726 _S_do(_Us&&... __us)
1727 {
1728 return _Ret(std::forward<_Us>(__us)...);
1729 }
1730 };
1731
1732 /// tuple_cat
1733 template<typename... _Tpls, typename = typename
1734 enable_if<__and_<__is_tuple_like<_Tpls>...>::value>::type>
1735 constexpr auto
1736 tuple_cat(_Tpls&&... __tpls)
1737 -> typename __tuple_cat_result<_Tpls...>::__type
1738 {
1739 typedef typename __tuple_cat_result<_Tpls...>::__type __ret;
1740 typedef typename __make_1st_indices<_Tpls...>::__type __idx;
1741 typedef __tuple_concater<__ret, __idx, _Tpls...> __concater;
1742 return __concater::_S_do(std::forward<_Tpls>(__tpls)...);
1743 }
1744
1745 // _GLIBCXX_RESOLVE_LIB_DEFECTS
1746 // 2301. Why is tie not constexpr?
1747 /// tie
1748 template<typename... _Elements>
1749 constexpr tuple<_Elements&...>
1750 tie(_Elements&... __args) noexcept
1751 { return tuple<_Elements&...>(__args...); }
1752
1753 /// swap
1754 template<typename... _Elements>
1755 _GLIBCXX20_CONSTEXPR
1756 inline
1757#if __cplusplus > 201402L || !defined(__STRICT_ANSI__) // c++1z or gnu++11
1758 // Constrained free swap overload, see p0185r1
1759 typename enable_if<__and_<__is_swappable<_Elements>...>::value
1760 >::type
1761#else
1762 void
1763#endif
1764 swap(tuple<_Elements...>& __x, tuple<_Elements...>& __y)
1765 noexcept(noexcept(__x.swap(__y)))
1766 { __x.swap(__y); }
1767
1768#if __cplusplus > 201402L || !defined(__STRICT_ANSI__) // c++1z or gnu++11
1769 template<typename... _Elements>
1770 _GLIBCXX20_CONSTEXPR
1771 typename enable_if<!__and_<__is_swappable<_Elements>...>::value>::type
1772 swap(tuple<_Elements...>&, tuple<_Elements...>&) = delete;
1773#endif
1774
1775 // A class (and instance) which can be used in 'tie' when an element
1776 // of a tuple is not required.
1777 // _GLIBCXX14_CONSTEXPR
1778 // 2933. PR for LWG 2773 could be clearer
1779 struct _Swallow_assign
1780 {
1781 template<class _Tp>
1782 _GLIBCXX14_CONSTEXPR const _Swallow_assign&
1783 operator=(const _Tp&) const
1784 { return *this; }
1785 };
1786
1787 // _GLIBCXX_RESOLVE_LIB_DEFECTS
1788 // 2773. Making std::ignore constexpr
1789 _GLIBCXX17_INLINE constexpr _Swallow_assign ignore{};
1790
1791 /// Partial specialization for tuples
1792 template<typename... _Types, typename _Alloc>
1793 struct uses_allocator<tuple<_Types...>, _Alloc> : true_type { };
1794
1795 // See stl_pair.h...
1796 /** "piecewise construction" using a tuple of arguments for each member.
1797 *
1798 * @param __first Arguments for the first member of the pair.
1799 * @param __second Arguments for the second member of the pair.
1800 *
1801 * The elements of each tuple will be used as the constructor arguments
1802 * for the data members of the pair.
1803 */
1804 template<class _T1, class _T2>
1805 template<typename... _Args1, typename... _Args2>
1806 _GLIBCXX20_CONSTEXPR
1807 inline
1808 pair<_T1, _T2>::
1809 pair(piecewise_construct_t,
1810 tuple<_Args1...> __first, tuple<_Args2...> __second)
1811 : pair(__first, __second,
1812 typename _Build_index_tuple<sizeof...(_Args1)>::__type(),
1813 typename _Build_index_tuple<sizeof...(_Args2)>::__type())
1814 { }
1815
1816 template<class _T1, class _T2>
1817 template<typename... _Args1, size_t... _Indexes1,
1818 typename... _Args2, size_t... _Indexes2>
1819 _GLIBCXX20_CONSTEXPR inline
1820 pair<_T1, _T2>::
1821 pair(tuple<_Args1...>& __tuple1, tuple<_Args2...>& __tuple2,
1822 _Index_tuple<_Indexes1...>, _Index_tuple<_Indexes2...>)
1823 : first(std::forward<_Args1>(std::get<_Indexes1>(__tuple1))...),
1824 second(std::forward<_Args2>(std::get<_Indexes2>(__tuple2))...)
1825 { }
1826
1827#if __cplusplus >= 201703L
1828
1829 // Unpack a std::tuple into a type trait and use its value.
1830 // For cv std::tuple<_Up> the result is _Trait<_Tp, cv _Up...>::value.
1831 // For cv std::tuple<_Up>& the result is _Trait<_Tp, cv _Up&...>::value.
1832 // Otherwise the result is false (because we don't know if std::get throws).
1833 template<template<typename...> class _Trait, typename _Tp, typename _Tuple>
1834 inline constexpr bool __unpack_std_tuple = false;
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, tuple<_Up...>&>
1842 = _Trait<_Tp, _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 template<template<typename...> class _Trait, typename _Tp, typename... _Up>
1849 inline constexpr bool __unpack_std_tuple<_Trait, _Tp, const tuple<_Up...>&>
1850 = _Trait<_Tp, const _Up&...>::value;
1851
1852# define __cpp_lib_apply 201603
1853
1854 template <typename _Fn, typename _Tuple, size_t... _Idx>
1855 constexpr decltype(auto)
1856 __apply_impl(_Fn&& __f, _Tuple&& __t, index_sequence<_Idx...>)
1857 {
1858 return std::__invoke(std::forward<_Fn>(__f),
1859 std::get<_Idx>(std::forward<_Tuple>(__t))...);
1860 }
1861
1862 template <typename _Fn, typename _Tuple>
1863 constexpr decltype(auto)
1864 apply(_Fn&& __f, _Tuple&& __t)
1865 noexcept(__unpack_std_tuple<is_nothrow_invocable, _Fn, _Tuple>)
1866 {
1867 using _Indices
1868 = make_index_sequence<tuple_size_v<remove_reference_t<_Tuple>>>;
1869 return std::__apply_impl(std::forward<_Fn>(__f),
1870 std::forward<_Tuple>(__t),
1871 _Indices{});
1872 }
1873
1874#define __cpp_lib_make_from_tuple 201606
1875
1876 template <typename _Tp, typename _Tuple, size_t... _Idx>
1877 constexpr _Tp
1878 __make_from_tuple_impl(_Tuple&& __t, index_sequence<_Idx...>)
1879 { return _Tp(std::get<_Idx>(std::forward<_Tuple>(__t))...); }
1880
1881 template <typename _Tp, typename _Tuple>
1882 constexpr _Tp
1883 make_from_tuple(_Tuple&& __t)
1884 noexcept(__unpack_std_tuple<is_nothrow_constructible, _Tp, _Tuple>)
1885 {
1886 return __make_from_tuple_impl<_Tp>(
1887 std::forward<_Tuple>(__t),
1888 make_index_sequence<tuple_size_v<remove_reference_t<_Tuple>>>{});
1889 }
1890#endif // C++17
1891
1892 /// @}
1893
1894_GLIBCXX_END_NAMESPACE_VERSION
1895} // namespace std
1896
1897#endif // C++11
1898
1899#endif // _GLIBCXX_TUPLE
1900