Line data Source code
1 : // Pair implementation -*- C++ -*-
2 :
3 : // Copyright (C) 2001-2024 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 : /*
26 : *
27 : * Copyright (c) 1994
28 : * Hewlett-Packard Company
29 : *
30 : * Permission to use, copy, modify, distribute and sell this software
31 : * and its documentation for any purpose is hereby granted without fee,
32 : * provided that the above copyright notice appear in all copies and
33 : * that both that copyright notice and this permission notice appear
34 : * in supporting documentation. Hewlett-Packard Company makes no
35 : * representations about the suitability of this software for any
36 : * purpose. It is provided "as is" without express or implied warranty.
37 : *
38 : *
39 : * Copyright (c) 1996,1997
40 : * Silicon Graphics Computer Systems, Inc.
41 : *
42 : * Permission to use, copy, modify, distribute and sell this software
43 : * and its documentation for any purpose is hereby granted without fee,
44 : * provided that the above copyright notice appear in all copies and
45 : * that both that copyright notice and this permission notice appear
46 : * in supporting documentation. Silicon Graphics makes no
47 : * representations about the suitability of this software for any
48 : * purpose. It is provided "as is" without express or implied warranty.
49 : */
50 :
51 : /** @file bits/stl_pair.h
52 : * This is an internal header file, included by other library headers.
53 : * Do not attempt to use it directly. @headername{utility}
54 : */
55 :
56 : #ifndef _STL_PAIR_H
57 : #define _STL_PAIR_H 1
58 :
59 : #if __cplusplus >= 201103L
60 : # include <type_traits> // for std::__decay_and_strip
61 : # include <bits/move.h> // for std::move / std::forward, and std::swap
62 : # include <bits/utility.h> // for std::tuple_element, std::tuple_size
63 : #endif
64 : #if __cplusplus >= 202002L
65 : # include <compare>
66 : #endif
67 :
68 : namespace std _GLIBCXX_VISIBILITY(default)
69 : {
70 : _GLIBCXX_BEGIN_NAMESPACE_VERSION
71 :
72 : /**
73 : * @addtogroup utilities
74 : * @{
75 : */
76 :
77 : #if __cplusplus >= 201103L
78 : /// Tag type for piecewise construction of std::pair objects.
79 : struct piecewise_construct_t { explicit piecewise_construct_t() = default; };
80 :
81 : /// Tag for piecewise construction of std::pair objects.
82 : _GLIBCXX17_INLINE constexpr piecewise_construct_t piecewise_construct =
83 : piecewise_construct_t();
84 :
85 : /// @cond undocumented
86 :
87 : // Forward declarations.
88 : template<typename _T1, typename _T2>
89 : struct pair;
90 :
91 : template<typename...>
92 : class tuple;
93 :
94 : // Declarations of std::array and its std::get overloads, so that
95 : // std::tuple_cat can use them if <tuple> is included before <array>.
96 : // We also declare the other std::get overloads here so that they're
97 : // visible to the P2165R4 tuple-like constructors of pair and tuple.
98 : template<typename _Tp, size_t _Nm>
99 : struct array;
100 :
101 : template<size_t...>
102 : struct _Index_tuple;
103 :
104 : template<size_t _Int, class _Tp1, class _Tp2>
105 : constexpr typename tuple_element<_Int, pair<_Tp1, _Tp2>>::type&
106 : get(pair<_Tp1, _Tp2>& __in) noexcept;
107 :
108 : template<size_t _Int, class _Tp1, class _Tp2>
109 : constexpr typename tuple_element<_Int, pair<_Tp1, _Tp2>>::type&&
110 : get(pair<_Tp1, _Tp2>&& __in) noexcept;
111 :
112 : template<size_t _Int, class _Tp1, class _Tp2>
113 : constexpr const typename tuple_element<_Int, pair<_Tp1, _Tp2>>::type&
114 : get(const pair<_Tp1, _Tp2>& __in) noexcept;
115 :
116 : template<size_t _Int, class _Tp1, class _Tp2>
117 : constexpr const typename tuple_element<_Int, pair<_Tp1, _Tp2>>::type&&
118 : get(const pair<_Tp1, _Tp2>&& __in) noexcept;
119 :
120 : template<size_t __i, typename... _Elements>
121 : constexpr __tuple_element_t<__i, tuple<_Elements...>>&
122 : get(tuple<_Elements...>& __t) noexcept;
123 :
124 : template<size_t __i, typename... _Elements>
125 : constexpr const __tuple_element_t<__i, tuple<_Elements...>>&
126 : get(const tuple<_Elements...>& __t) noexcept;
127 :
128 : template<size_t __i, typename... _Elements>
129 : constexpr __tuple_element_t<__i, tuple<_Elements...>>&&
130 : get(tuple<_Elements...>&& __t) noexcept;
131 :
132 : template<size_t __i, typename... _Elements>
133 : constexpr const __tuple_element_t<__i, tuple<_Elements...>>&&
134 : get(const tuple<_Elements...>&& __t) noexcept;
135 :
136 : template<size_t _Int, typename _Tp, size_t _Nm>
137 : constexpr _Tp&
138 : get(array<_Tp, _Nm>&) noexcept;
139 :
140 : template<size_t _Int, typename _Tp, size_t _Nm>
141 : constexpr _Tp&&
142 : get(array<_Tp, _Nm>&&) noexcept;
143 :
144 : template<size_t _Int, typename _Tp, size_t _Nm>
145 : constexpr const _Tp&
146 : get(const array<_Tp, _Nm>&) noexcept;
147 :
148 : template<size_t _Int, typename _Tp, size_t _Nm>
149 : constexpr const _Tp&&
150 : get(const array<_Tp, _Nm>&&) noexcept;
151 :
152 : #if ! __cpp_lib_concepts
153 : // Concept utility functions, reused in conditionally-explicit
154 : // constructors.
155 : // See PR 70437, don't look at is_constructible or
156 : // is_convertible if the types are the same to
157 : // avoid querying those properties for incomplete types.
158 : template <bool, typename _T1, typename _T2>
159 : struct _PCC
160 : {
161 : template <typename _U1, typename _U2>
162 : static constexpr bool _ConstructiblePair()
163 : {
164 : return __and_<is_constructible<_T1, const _U1&>,
165 : is_constructible<_T2, const _U2&>>::value;
166 : }
167 :
168 : template <typename _U1, typename _U2>
169 : static constexpr bool _ImplicitlyConvertiblePair()
170 : {
171 : return __and_<is_convertible<const _U1&, _T1>,
172 : is_convertible<const _U2&, _T2>>::value;
173 : }
174 :
175 : template <typename _U1, typename _U2>
176 : static constexpr bool _MoveConstructiblePair()
177 : {
178 : return __and_<is_constructible<_T1, _U1&&>,
179 : is_constructible<_T2, _U2&&>>::value;
180 : }
181 :
182 : template <typename _U1, typename _U2>
183 : static constexpr bool _ImplicitlyMoveConvertiblePair()
184 : {
185 : return __and_<is_convertible<_U1&&, _T1>,
186 : is_convertible<_U2&&, _T2>>::value;
187 : }
188 : };
189 :
190 : template <typename _T1, typename _T2>
191 : struct _PCC<false, _T1, _T2>
192 : {
193 : template <typename _U1, typename _U2>
194 : static constexpr bool _ConstructiblePair()
195 : {
196 : return false;
197 : }
198 :
199 : template <typename _U1, typename _U2>
200 : static constexpr bool _ImplicitlyConvertiblePair()
201 : {
202 : return false;
203 : }
204 :
205 : template <typename _U1, typename _U2>
206 : static constexpr bool _MoveConstructiblePair()
207 : {
208 : return false;
209 : }
210 :
211 : template <typename _U1, typename _U2>
212 : static constexpr bool _ImplicitlyMoveConvertiblePair()
213 : {
214 : return false;
215 : }
216 : };
217 : #endif // lib concepts
218 : #endif // C++11
219 :
220 : #if __glibcxx_tuple_like // >= C++23
221 : template<typename _Tp>
222 : inline constexpr bool __is_tuple_v = false;
223 :
224 : template<typename... _Ts>
225 : inline constexpr bool __is_tuple_v<tuple<_Ts...>> = true;
226 :
227 : // TODO: Reuse __is_tuple_like from <type_traits>?
228 : template<typename _Tp>
229 : inline constexpr bool __is_tuple_like_v = false;
230 :
231 : template<typename... _Elements>
232 : inline constexpr bool __is_tuple_like_v<tuple<_Elements...>> = true;
233 :
234 : template<typename _T1, typename _T2>
235 : inline constexpr bool __is_tuple_like_v<pair<_T1, _T2>> = true;
236 :
237 : template<typename _Tp, size_t _Nm>
238 : inline constexpr bool __is_tuple_like_v<array<_Tp, _Nm>> = true;
239 :
240 : // __is_tuple_like_v<subrange> is defined in <bits/ranges_util.h>.
241 :
242 : template<typename _Tp>
243 : concept __tuple_like = __is_tuple_like_v<remove_cvref_t<_Tp>>;
244 :
245 : template<typename _Tp>
246 : concept __pair_like = __tuple_like<_Tp> && tuple_size_v<remove_cvref_t<_Tp>> == 2;
247 :
248 : template<typename _Tp, typename _Tuple>
249 : concept __eligible_tuple_like
250 : = __detail::__different_from<_Tp, _Tuple> && __tuple_like<_Tp>
251 : && (tuple_size_v<remove_cvref_t<_Tp>> == tuple_size_v<_Tuple>)
252 : && !ranges::__detail::__is_subrange<remove_cvref_t<_Tp>>;
253 :
254 : template<typename _Tp, typename _Pair>
255 : concept __eligible_pair_like
256 : = __detail::__different_from<_Tp, _Pair> && __pair_like<_Tp>
257 : && !ranges::__detail::__is_subrange<remove_cvref_t<_Tp>>;
258 : #endif // C++23
259 :
260 : template<typename _U1, typename _U2> class __pair_base
261 : {
262 : #if __cplusplus >= 201103L && ! __cpp_lib_concepts
263 : template<typename _T1, typename _T2> friend struct pair;
264 : __pair_base() = default;
265 : ~__pair_base() = default;
266 : __pair_base(const __pair_base&) = default;
267 : __pair_base& operator=(const __pair_base&) = delete;
268 : #endif // C++11
269 : };
270 :
271 : /// @endcond
272 :
273 : /**
274 : * @brief Struct holding two objects of arbitrary type.
275 : *
276 : * @tparam _T1 Type of first object.
277 : * @tparam _T2 Type of second object.
278 : *
279 : * <https://gcc.gnu.org/onlinedocs/libstdc++/manual/utilities.html>
280 : *
281 : * @headerfile utility
282 : */
283 : template<typename _T1, typename _T2>
284 : struct pair
285 : : public __pair_base<_T1, _T2>
286 : {
287 : typedef _T1 first_type; ///< The type of the `first` member
288 : typedef _T2 second_type; ///< The type of the `second` member
289 :
290 : _T1 first; ///< The first member
291 : _T2 second; ///< The second member
292 :
293 : #if __cplusplus >= 201103L
294 : constexpr pair(const pair&) = default; ///< Copy constructor
295 : constexpr pair(pair&&) = default; ///< Move constructor
296 :
297 : template<typename... _Args1, typename... _Args2>
298 : _GLIBCXX20_CONSTEXPR
299 : pair(piecewise_construct_t, tuple<_Args1...>, tuple<_Args2...>);
300 :
301 : /// Swap the first members and then the second members.
302 : _GLIBCXX20_CONSTEXPR void
303 : swap(pair& __p)
304 : noexcept(__and_<__is_nothrow_swappable<_T1>,
305 : __is_nothrow_swappable<_T2>>::value)
306 : {
307 : using std::swap;
308 : swap(first, __p.first);
309 : swap(second, __p.second);
310 : }
311 :
312 : #if __glibcxx_ranges_zip // >= C++23
313 : // As an extension, we constrain the const swap member function in order
314 : // to continue accepting explicit instantiation of pairs whose elements
315 : // are not all const swappable. Without this constraint, such an
316 : // explicit instantiation would also instantiate the ill-formed body of
317 : // this function and yield a hard error. This constraint shouldn't
318 : // affect the behavior of valid programs.
319 : constexpr void
320 : swap(const pair& __p) const
321 : noexcept(__and_v<__is_nothrow_swappable<const _T1>,
322 : __is_nothrow_swappable<const _T2>>)
323 : requires is_swappable_v<const _T1> && is_swappable_v<const _T2>
324 : {
325 : using std::swap;
326 : swap(first, __p.first);
327 : swap(second, __p.second);
328 : }
329 : #endif // C++23
330 :
331 : private:
332 : template<typename... _Args1, size_t... _Indexes1,
333 : typename... _Args2, size_t... _Indexes2>
334 : _GLIBCXX20_CONSTEXPR
335 : pair(tuple<_Args1...>&, tuple<_Args2...>&,
336 : _Index_tuple<_Indexes1...>, _Index_tuple<_Indexes2...>);
337 : public:
338 :
339 : #if __cpp_lib_concepts
340 : // C++20 implementation using concepts, explicit(bool), fully constexpr.
341 :
342 : /// Default constructor
343 : constexpr
344 : explicit(__not_<__and_<__is_implicitly_default_constructible<_T1>,
345 : __is_implicitly_default_constructible<_T2>>>())
346 : pair()
347 : requires is_default_constructible_v<_T1>
348 : && is_default_constructible_v<_T2>
349 : : first(), second()
350 : { }
351 :
352 : private:
353 :
354 : /// @cond undocumented
355 : template<typename _U1, typename _U2>
356 : static constexpr bool
357 : _S_constructible()
358 : {
359 : if constexpr (is_constructible_v<_T1, _U1>)
360 : return is_constructible_v<_T2, _U2>;
361 : return false;
362 : }
363 :
364 : template<typename _U1, typename _U2>
365 : static constexpr bool
366 : _S_nothrow_constructible()
367 : {
368 : if constexpr (is_nothrow_constructible_v<_T1, _U1>)
369 : return is_nothrow_constructible_v<_T2, _U2>;
370 : return false;
371 : }
372 :
373 : template<typename _U1, typename _U2>
374 : static constexpr bool
375 : _S_convertible()
376 : {
377 : if constexpr (is_convertible_v<_U1, _T1>)
378 : return is_convertible_v<_U2, _T2>;
379 : return false;
380 : }
381 :
382 : // True if construction from _U1 and _U2 would create a dangling ref.
383 : template<typename _U1, typename _U2>
384 : static constexpr bool
385 : _S_dangles()
386 : {
387 : #if __has_builtin(__reference_constructs_from_temporary)
388 : if constexpr (__reference_constructs_from_temporary(_T1, _U1&&))
389 : return true;
390 : else
391 : return __reference_constructs_from_temporary(_T2, _U2&&);
392 : #else
393 : return false;
394 : #endif
395 : }
396 :
397 : #if __glibcxx_tuple_like // >= C++23
398 : template<typename _UPair>
399 : static constexpr bool
400 : _S_constructible_from_pair_like()
401 : {
402 : return _S_constructible<decltype(std::get<0>(std::declval<_UPair>())),
403 : decltype(std::get<1>(std::declval<_UPair>()))>();
404 : }
405 :
406 : template<typename _UPair>
407 : static constexpr bool
408 : _S_convertible_from_pair_like()
409 : {
410 : return _S_convertible<decltype(std::get<0>(std::declval<_UPair>())),
411 : decltype(std::get<1>(std::declval<_UPair>()))>();
412 : }
413 :
414 : template<typename _UPair>
415 : static constexpr bool
416 : _S_dangles_from_pair_like()
417 : {
418 : return _S_dangles<decltype(std::get<0>(std::declval<_UPair>())),
419 : decltype(std::get<1>(std::declval<_UPair>()))>();
420 : }
421 : #endif // C++23
422 : /// @endcond
423 :
424 : public:
425 :
426 : /// Constructor accepting lvalues of `first_type` and `second_type`
427 : constexpr explicit(!_S_convertible<const _T1&, const _T2&>())
428 : pair(const _T1& __x, const _T2& __y)
429 : noexcept(_S_nothrow_constructible<const _T1&, const _T2&>())
430 : requires (_S_constructible<const _T1&, const _T2&>())
431 : : first(__x), second(__y)
432 : { }
433 :
434 : /// Constructor accepting two values of arbitrary types
435 : #if __cplusplus > 202002L
436 : template<typename _U1 = _T1, typename _U2 = _T2>
437 : #else
438 : template<typename _U1, typename _U2>
439 : #endif
440 : requires (_S_constructible<_U1, _U2>()) && (!_S_dangles<_U1, _U2>())
441 : constexpr explicit(!_S_convertible<_U1, _U2>())
442 : pair(_U1&& __x, _U2&& __y)
443 : noexcept(_S_nothrow_constructible<_U1, _U2>())
444 : : first(std::forward<_U1>(__x)), second(std::forward<_U2>(__y))
445 : { }
446 :
447 : #if __cplusplus > 202002L
448 : template<typename _U1 = _T1, typename _U2 = _T2>
449 : #else
450 : template<typename _U1, typename _U2>
451 : #endif
452 : requires (_S_constructible<_U1, _U2>()) && (_S_dangles<_U1, _U2>())
453 : constexpr explicit(!_S_convertible<_U1, _U2>())
454 : pair(_U1&&, _U2&&) = delete;
455 :
456 : /// Converting constructor from a const `pair<U1, U2>` lvalue
457 : template<typename _U1, typename _U2>
458 : requires (_S_constructible<const _U1&, const _U2&>())
459 : && (!_S_dangles<_U1, _U2>())
460 : constexpr explicit(!_S_convertible<const _U1&, const _U2&>())
461 : pair(const pair<_U1, _U2>& __p)
462 : noexcept(_S_nothrow_constructible<const _U1&, const _U2&>())
463 : : first(__p.first), second(__p.second)
464 : { }
465 :
466 : template<typename _U1, typename _U2>
467 : requires (_S_constructible<const _U1&, const _U2&>())
468 : && (_S_dangles<const _U1&, const _U2&>())
469 : constexpr explicit(!_S_convertible<const _U1&, const _U2&>())
470 : pair(const pair<_U1, _U2>&) = delete;
471 :
472 : /// Converting constructor from a non-const `pair<U1, U2>` rvalue
473 : template<typename _U1, typename _U2>
474 : requires (_S_constructible<_U1, _U2>()) && (!_S_dangles<_U1, _U2>())
475 : constexpr explicit(!_S_convertible<_U1, _U2>())
476 : pair(pair<_U1, _U2>&& __p)
477 : noexcept(_S_nothrow_constructible<_U1, _U2>())
478 : : first(std::forward<_U1>(__p.first)),
479 : second(std::forward<_U2>(__p.second))
480 : { }
481 :
482 : template<typename _U1, typename _U2>
483 : requires (_S_constructible<_U1, _U2>()) && (_S_dangles<_U1, _U2>())
484 : constexpr explicit(!_S_convertible<_U1, _U2>())
485 : pair(pair<_U1, _U2>&&) = delete;
486 :
487 : #if __glibcxx_ranges_zip // >= C++23
488 : /// Converting constructor from a non-const `pair<U1, U2>` lvalue
489 : template<typename _U1, typename _U2>
490 : requires (_S_constructible<_U1&, _U2&>()) && (!_S_dangles<_U1&, _U2&>())
491 : constexpr explicit(!_S_convertible<_U1&, _U2&>())
492 : pair(pair<_U1, _U2>& __p)
493 : noexcept(_S_nothrow_constructible<_U1&, _U2&>())
494 : : first(__p.first), second(__p.second)
495 : { }
496 :
497 : template<typename _U1, typename _U2>
498 : requires (_S_constructible<_U1&, _U2&>()) && (_S_dangles<_U1&, _U2&>())
499 : constexpr explicit(!_S_convertible<_U1&, _U2&>())
500 : pair(pair<_U1, _U2>&) = delete;
501 :
502 : /// Converting constructor from a const `pair<U1, U2>` rvalue
503 : template<typename _U1, typename _U2>
504 : requires (_S_constructible<const _U1, const _U2>())
505 : && (!_S_dangles<const _U1, const _U2>())
506 : constexpr explicit(!_S_convertible<const _U1, const _U2>())
507 : pair(const pair<_U1, _U2>&& __p)
508 : noexcept(_S_nothrow_constructible<const _U1, const _U2>())
509 : : first(std::forward<const _U1>(__p.first)),
510 : second(std::forward<const _U2>(__p.second))
511 : { }
512 :
513 : template<typename _U1, typename _U2>
514 : requires (_S_constructible<const _U1, const _U2>())
515 : && (_S_dangles<const _U1, const _U2>())
516 : constexpr explicit(!_S_convertible<const _U1, const _U2>())
517 : pair(const pair<_U1, _U2>&&) = delete;
518 : #endif // C++23
519 :
520 : #if __glibcxx_tuple_like // >= C++23
521 : template<__eligible_pair_like<pair> _UPair>
522 : requires (_S_constructible_from_pair_like<_UPair>())
523 : && (!_S_dangles_from_pair_like<_UPair>())
524 : constexpr explicit(!_S_convertible_from_pair_like<_UPair>())
525 : pair(_UPair&& __p)
526 : : first(std::get<0>(std::forward<_UPair>(__p))),
527 : second(std::get<1>(std::forward<_UPair>(__p)))
528 : { }
529 :
530 : template<__eligible_pair_like<pair> _UPair>
531 : requires (_S_constructible_from_pair_like<_UPair>())
532 : && (_S_dangles_from_pair_like<_UPair>())
533 : constexpr explicit(!_S_convertible_from_pair_like<_UPair>())
534 : pair(_UPair&&) = delete;
535 : #endif // C++23
536 :
537 : private:
538 : /// @cond undocumented
539 : template<typename _U1, typename _U2>
540 : static constexpr bool
541 : _S_assignable()
542 : {
543 : if constexpr (is_assignable_v<_T1&, _U1>)
544 : return is_assignable_v<_T2&, _U2>;
545 : return false;
546 : }
547 :
548 : template<typename _U1, typename _U2>
549 : static constexpr bool
550 : _S_const_assignable()
551 : {
552 : if constexpr (is_assignable_v<const _T1&, _U1>)
553 : return is_assignable_v<const _T2&, _U2>;
554 : return false;
555 : }
556 :
557 : template<typename _U1, typename _U2>
558 : static constexpr bool
559 : _S_nothrow_assignable()
560 : {
561 : if constexpr (is_nothrow_assignable_v<_T1&, _U1>)
562 : return is_nothrow_assignable_v<_T2&, _U2>;
563 : return false;
564 : }
565 :
566 : #if __glibcxx_tuple_like // >= C++23
567 : template<typename _UPair>
568 : static constexpr bool
569 : _S_assignable_from_tuple_like()
570 : {
571 : return _S_assignable<decltype(std::get<0>(std::declval<_UPair>())),
572 : decltype(std::get<1>(std::declval<_UPair>()))>();
573 : }
574 :
575 : template<typename _UPair>
576 : static constexpr bool
577 : _S_const_assignable_from_tuple_like()
578 : {
579 : return _S_const_assignable<decltype(std::get<0>(std::declval<_UPair>())),
580 : decltype(std::get<1>(std::declval<_UPair>()))>();
581 : }
582 : #endif // C++23
583 : /// @endcond
584 :
585 : public:
586 :
587 : pair& operator=(const pair&) = delete;
588 :
589 : /// Copy assignment operator
590 : constexpr pair&
591 : operator=(const pair& __p)
592 : noexcept(_S_nothrow_assignable<const _T1&, const _T2&>())
593 : requires (_S_assignable<const _T1&, const _T2&>())
594 : {
595 : first = __p.first;
596 : second = __p.second;
597 : return *this;
598 : }
599 :
600 : /// Move assignment operator
601 : constexpr pair&
602 : operator=(pair&& __p)
603 : noexcept(_S_nothrow_assignable<_T1, _T2>())
604 : requires (_S_assignable<_T1, _T2>())
605 : {
606 : first = std::forward<first_type>(__p.first);
607 : second = std::forward<second_type>(__p.second);
608 : return *this;
609 : }
610 :
611 : /// Converting assignment from a const `pair<U1, U2>` lvalue
612 : template<typename _U1, typename _U2>
613 : constexpr pair&
614 : operator=(const pair<_U1, _U2>& __p)
615 : noexcept(_S_nothrow_assignable<const _U1&, const _U2&>())
616 : requires (_S_assignable<const _U1&, const _U2&>())
617 : {
618 : first = __p.first;
619 : second = __p.second;
620 : return *this;
621 : }
622 :
623 : /// Converting assignment from a non-const `pair<U1, U2>` rvalue
624 : template<typename _U1, typename _U2>
625 : constexpr pair&
626 : operator=(pair<_U1, _U2>&& __p)
627 : noexcept(_S_nothrow_assignable<_U1, _U2>())
628 : requires (_S_assignable<_U1, _U2>())
629 : {
630 : first = std::forward<_U1>(__p.first);
631 : second = std::forward<_U2>(__p.second);
632 : return *this;
633 : }
634 :
635 : #if __glibcxx_ranges_zip // >= C++23
636 : /// Copy assignment operator (const)
637 : constexpr const pair&
638 : operator=(const pair& __p) const
639 : requires (_S_const_assignable<const first_type&, const second_type&>())
640 : {
641 : first = __p.first;
642 : second = __p.second;
643 : return *this;
644 : }
645 :
646 : /// Move assignment operator (const)
647 : constexpr const pair&
648 : operator=(pair&& __p) const
649 : requires (_S_const_assignable<first_type, second_type>())
650 : {
651 : first = std::forward<first_type>(__p.first);
652 : second = std::forward<second_type>(__p.second);
653 : return *this;
654 : }
655 :
656 : /// Converting assignment from a const `pair<U1, U2>` lvalue
657 : template<typename _U1, typename _U2>
658 : constexpr const pair&
659 : operator=(const pair<_U1, _U2>& __p) const
660 : requires (_S_const_assignable<const _U1&, const _U2&>())
661 : {
662 : first = __p.first;
663 : second = __p.second;
664 : return *this;
665 : }
666 :
667 : /// Converting assignment from a non-const `pair<U1, U2>` rvalue
668 : template<typename _U1, typename _U2>
669 : constexpr const pair&
670 : operator=(pair<_U1, _U2>&& __p) const
671 : requires (_S_const_assignable<_U1, _U2>())
672 : {
673 : first = std::forward<_U1>(__p.first);
674 : second = std::forward<_U2>(__p.second);
675 : return *this;
676 : }
677 : #endif // C++23
678 :
679 : #if __glibcxx_tuple_like // >= C++23
680 : template<__eligible_pair_like<pair> _UPair>
681 : requires (_S_assignable_from_tuple_like<_UPair>())
682 : constexpr pair&
683 : operator=(_UPair&& __p)
684 : {
685 : first = std::get<0>(std::forward<_UPair>(__p));
686 : second = std::get<1>(std::forward<_UPair>(__p));
687 : return *this;
688 : }
689 :
690 : template<__eligible_pair_like<pair> _UPair>
691 : requires (_S_const_assignable_from_tuple_like<_UPair>())
692 : constexpr const pair&
693 : operator=(_UPair&& __p) const
694 : {
695 : first = std::get<0>(std::forward<_UPair>(__p));
696 : second = std::get<1>(std::forward<_UPair>(__p));
697 : return *this;
698 : }
699 : #endif // C++23
700 :
701 : #else // !__cpp_lib_concepts
702 : // C++11/14/17 implementation using enable_if, partially constexpr.
703 :
704 : /// @cond undocumented
705 : // Error if construction from _U1 and _U2 would create a dangling ref.
706 : #if __has_builtin(__reference_constructs_from_temporary) \
707 : && defined _GLIBCXX_DEBUG
708 : # define __glibcxx_no_dangling_refs(_U1, _U2) \
709 : static_assert(!__reference_constructs_from_temporary(_T1, _U1) \
710 : && !__reference_constructs_from_temporary(_T2, _U2), \
711 : "std::pair constructor creates a dangling reference")
712 : #else
713 : # define __glibcxx_no_dangling_refs(_U1, _U2)
714 : #endif
715 : /// @endcond
716 :
717 : /** The default constructor creates @c first and @c second using their
718 : * respective default constructors. */
719 : template <typename _U1 = _T1,
720 : typename _U2 = _T2,
721 : typename enable_if<__and_<
722 : __is_implicitly_default_constructible<_U1>,
723 : __is_implicitly_default_constructible<_U2>>
724 : ::value, bool>::type = true>
725 : constexpr pair()
726 : : first(), second() { }
727 :
728 : template <typename _U1 = _T1,
729 : typename _U2 = _T2,
730 : typename enable_if<__and_<
731 : is_default_constructible<_U1>,
732 : is_default_constructible<_U2>,
733 : __not_<
734 : __and_<__is_implicitly_default_constructible<_U1>,
735 : __is_implicitly_default_constructible<_U2>>>>
736 : ::value, bool>::type = false>
737 : explicit constexpr pair()
738 : : first(), second() { }
739 :
740 : // Shortcut for constraining the templates that don't take pairs.
741 : /// @cond undocumented
742 : using _PCCP = _PCC<true, _T1, _T2>;
743 : /// @endcond
744 :
745 : /// Construct from two const lvalues, allowing implicit conversions.
746 : template<typename _U1 = _T1, typename _U2=_T2, typename
747 : enable_if<_PCCP::template
748 : _ConstructiblePair<_U1, _U2>()
749 : && _PCCP::template
750 : _ImplicitlyConvertiblePair<_U1, _U2>(),
751 : bool>::type=true>
752 : constexpr pair(const _T1& __a, const _T2& __b)
753 : : first(__a), second(__b) { }
754 :
755 : /// Construct from two const lvalues, disallowing implicit conversions.
756 : template<typename _U1 = _T1, typename _U2=_T2, typename
757 : enable_if<_PCCP::template
758 : _ConstructiblePair<_U1, _U2>()
759 : && !_PCCP::template
760 : _ImplicitlyConvertiblePair<_U1, _U2>(),
761 : bool>::type=false>
762 : explicit constexpr pair(const _T1& __a, const _T2& __b)
763 : : first(__a), second(__b) { }
764 :
765 : // Shortcut for constraining the templates that take pairs.
766 : /// @cond undocumented
767 : template <typename _U1, typename _U2>
768 : using _PCCFP = _PCC<!is_same<_T1, _U1>::value
769 : || !is_same<_T2, _U2>::value,
770 : _T1, _T2>;
771 : /// @endcond
772 :
773 : template<typename _U1, typename _U2, typename
774 : enable_if<_PCCFP<_U1, _U2>::template
775 : _ConstructiblePair<_U1, _U2>()
776 : && _PCCFP<_U1, _U2>::template
777 : _ImplicitlyConvertiblePair<_U1, _U2>(),
778 : bool>::type=true>
779 : constexpr pair(const pair<_U1, _U2>& __p)
780 : : first(__p.first), second(__p.second)
781 : { __glibcxx_no_dangling_refs(const _U1&, const _U2&); }
782 :
783 : template<typename _U1, typename _U2, typename
784 : enable_if<_PCCFP<_U1, _U2>::template
785 : _ConstructiblePair<_U1, _U2>()
786 : && !_PCCFP<_U1, _U2>::template
787 : _ImplicitlyConvertiblePair<_U1, _U2>(),
788 : bool>::type=false>
789 : explicit constexpr pair(const pair<_U1, _U2>& __p)
790 : : first(__p.first), second(__p.second)
791 : { __glibcxx_no_dangling_refs(const _U1&, const _U2&); }
792 :
793 : #if _GLIBCXX_USE_DEPRECATED
794 : #if defined(__DEPRECATED)
795 : # define _GLIBCXX_DEPRECATED_PAIR_CTOR \
796 : __attribute__ ((__deprecated__ ("use 'nullptr' instead of '0' to " \
797 : "initialize std::pair of move-only " \
798 : "type and pointer")))
799 : #else
800 : # define _GLIBCXX_DEPRECATED_PAIR_CTOR
801 : #endif
802 :
803 : private:
804 : /// @cond undocumented
805 :
806 : // A type which can be constructed from literal zero, but not nullptr
807 : struct __zero_as_null_pointer_constant
808 : {
809 : __zero_as_null_pointer_constant(int __zero_as_null_pointer_constant::*)
810 : { }
811 : template<typename _Tp,
812 : typename = __enable_if_t<is_null_pointer<_Tp>::value>>
813 : __zero_as_null_pointer_constant(_Tp) = delete;
814 : };
815 : /// @endcond
816 : public:
817 :
818 : // Deprecated extensions to DR 811.
819 : // These allow construction from an rvalue and a literal zero,
820 : // in cases where the standard says the zero should be deduced as int
821 : template<typename _U1,
822 : __enable_if_t<__and_<__not_<is_reference<_U1>>,
823 : is_pointer<_T2>,
824 : is_constructible<_T1, _U1>,
825 : __not_<is_constructible<_T1, const _U1&>>,
826 : is_convertible<_U1, _T1>>::value,
827 : bool> = true>
828 : _GLIBCXX_DEPRECATED_PAIR_CTOR
829 : constexpr
830 : pair(_U1&& __x, __zero_as_null_pointer_constant, ...)
831 : : first(std::forward<_U1>(__x)), second(nullptr)
832 : { __glibcxx_no_dangling_refs(_U1&&, std::nullptr_t); }
833 :
834 : template<typename _U1,
835 : __enable_if_t<__and_<__not_<is_reference<_U1>>,
836 : is_pointer<_T2>,
837 : is_constructible<_T1, _U1>,
838 : __not_<is_constructible<_T1, const _U1&>>,
839 : __not_<is_convertible<_U1, _T1>>>::value,
840 : bool> = false>
841 : _GLIBCXX_DEPRECATED_PAIR_CTOR
842 : explicit constexpr
843 : pair(_U1&& __x, __zero_as_null_pointer_constant, ...)
844 : : first(std::forward<_U1>(__x)), second(nullptr)
845 : { __glibcxx_no_dangling_refs(_U1&&, std::nullptr_t); }
846 :
847 : template<typename _U2,
848 : __enable_if_t<__and_<is_pointer<_T1>,
849 : __not_<is_reference<_U2>>,
850 : is_constructible<_T2, _U2>,
851 : __not_<is_constructible<_T2, const _U2&>>,
852 : is_convertible<_U2, _T2>>::value,
853 : bool> = true>
854 : _GLIBCXX_DEPRECATED_PAIR_CTOR
855 : constexpr
856 : pair(__zero_as_null_pointer_constant, _U2&& __y, ...)
857 : : first(nullptr), second(std::forward<_U2>(__y))
858 : { __glibcxx_no_dangling_refs(std::nullptr_t, _U2&&); }
859 :
860 : template<typename _U2,
861 : __enable_if_t<__and_<is_pointer<_T1>,
862 : __not_<is_reference<_U2>>,
863 : is_constructible<_T2, _U2>,
864 : __not_<is_constructible<_T2, const _U2&>>,
865 : __not_<is_convertible<_U2, _T2>>>::value,
866 : bool> = false>
867 : _GLIBCXX_DEPRECATED_PAIR_CTOR
868 : explicit constexpr
869 : pair(__zero_as_null_pointer_constant, _U2&& __y, ...)
870 : : first(nullptr), second(std::forward<_U2>(__y))
871 : { __glibcxx_no_dangling_refs(std::nullptr_t, _U2&&); }
872 : #undef _GLIBCXX_DEPRECATED_PAIR_CTOR
873 : #endif
874 :
875 : template<typename _U1, typename _U2, typename
876 : enable_if<_PCCP::template
877 : _MoveConstructiblePair<_U1, _U2>()
878 : && _PCCP::template
879 : _ImplicitlyMoveConvertiblePair<_U1, _U2>(),
880 : bool>::type=true>
881 1081042 : constexpr pair(_U1&& __x, _U2&& __y)
882 1081042 : : first(std::forward<_U1>(__x)), second(std::forward<_U2>(__y))
883 1081042 : { __glibcxx_no_dangling_refs(_U1&&, _U2&&); }
884 :
885 : template<typename _U1, typename _U2, typename
886 : enable_if<_PCCP::template
887 : _MoveConstructiblePair<_U1, _U2>()
888 : && !_PCCP::template
889 : _ImplicitlyMoveConvertiblePair<_U1, _U2>(),
890 : bool>::type=false>
891 : explicit constexpr pair(_U1&& __x, _U2&& __y)
892 : : first(std::forward<_U1>(__x)), second(std::forward<_U2>(__y))
893 : { __glibcxx_no_dangling_refs(_U1&&, _U2&&); }
894 :
895 :
896 : template<typename _U1, typename _U2, typename
897 : enable_if<_PCCFP<_U1, _U2>::template
898 : _MoveConstructiblePair<_U1, _U2>()
899 : && _PCCFP<_U1, _U2>::template
900 : _ImplicitlyMoveConvertiblePair<_U1, _U2>(),
901 : bool>::type=true>
902 203282 : constexpr pair(pair<_U1, _U2>&& __p)
903 203282 : : first(std::forward<_U1>(__p.first)),
904 203282 : second(std::forward<_U2>(__p.second))
905 203282 : { __glibcxx_no_dangling_refs(_U1&&, _U2&&); }
906 :
907 : template<typename _U1, typename _U2, typename
908 : enable_if<_PCCFP<_U1, _U2>::template
909 : _MoveConstructiblePair<_U1, _U2>()
910 : && !_PCCFP<_U1, _U2>::template
911 : _ImplicitlyMoveConvertiblePair<_U1, _U2>(),
912 : bool>::type=false>
913 : explicit constexpr pair(pair<_U1, _U2>&& __p)
914 : : first(std::forward<_U1>(__p.first)),
915 : second(std::forward<_U2>(__p.second))
916 : { __glibcxx_no_dangling_refs(_U1&&, _U2&&); }
917 :
918 : #undef __glibcxx_no_dangling_refs
919 :
920 : pair&
921 : operator=(__conditional_t<__and_<is_copy_assignable<_T1>,
922 : is_copy_assignable<_T2>>::value,
923 : const pair&, const __nonesuch&> __p)
924 : {
925 : first = __p.first;
926 : second = __p.second;
927 : return *this;
928 : }
929 :
930 : pair&
931 : operator=(__conditional_t<__and_<is_move_assignable<_T1>,
932 : is_move_assignable<_T2>>::value,
933 : pair&&, __nonesuch&&> __p)
934 : noexcept(__and_<is_nothrow_move_assignable<_T1>,
935 : is_nothrow_move_assignable<_T2>>::value)
936 : {
937 : first = std::forward<first_type>(__p.first);
938 : second = std::forward<second_type>(__p.second);
939 : return *this;
940 : }
941 :
942 : template<typename _U1, typename _U2>
943 : typename enable_if<__and_<is_assignable<_T1&, const _U1&>,
944 : is_assignable<_T2&, const _U2&>>::value,
945 : pair&>::type
946 : operator=(const pair<_U1, _U2>& __p)
947 : {
948 : first = __p.first;
949 : second = __p.second;
950 : return *this;
951 : }
952 :
953 : template<typename _U1, typename _U2>
954 : typename enable_if<__and_<is_assignable<_T1&, _U1&&>,
955 : is_assignable<_T2&, _U2&&>>::value,
956 : pair&>::type
957 : operator=(pair<_U1, _U2>&& __p)
958 : {
959 : first = std::forward<_U1>(__p.first);
960 : second = std::forward<_U2>(__p.second);
961 : return *this;
962 : }
963 : #endif // lib concepts
964 : #else
965 : // C++03 implementation
966 :
967 : // _GLIBCXX_RESOLVE_LIB_DEFECTS
968 : // 265. std::pair::pair() effects overly restrictive
969 : /** The default constructor creates @c first and @c second using their
970 : * respective default constructors. */
971 : pair() : first(), second() { }
972 :
973 : /// Two objects may be passed to a `pair` constructor to be copied.
974 : pair(const _T1& __a, const _T2& __b)
975 : : first(__a), second(__b) { }
976 :
977 : /// Templated constructor to convert from other pairs.
978 : template<typename _U1, typename _U2>
979 : pair(const pair<_U1, _U2>& __p)
980 : : first(__p.first), second(__p.second)
981 : {
982 : #if __has_builtin(__reference_constructs_from_temporary)
983 : #pragma GCC diagnostic push
984 : #pragma GCC diagnostic ignored "-Wunused-local-typedefs"
985 : typedef int _DanglingCheck1[
986 : __reference_constructs_from_temporary(_T1, const _U1&) ? -1 : 1
987 : ];
988 : typedef int _DanglingCheck2[
989 : __reference_constructs_from_temporary(_T2, const _U2&) ? -1 : 1
990 : ];
991 : #pragma GCC diagnostic pop
992 : #endif
993 : }
994 : #endif // C++11
995 : };
996 :
997 : /// @relates pair @{
998 :
999 : #if __cpp_deduction_guides >= 201606
1000 : template<typename _T1, typename _T2> pair(_T1, _T2) -> pair<_T1, _T2>;
1001 : #endif
1002 :
1003 : #if __cpp_lib_three_way_comparison && __cpp_lib_concepts
1004 : // _GLIBCXX_RESOLVE_LIB_DEFECTS
1005 : // 3865. Sorting a range of pairs
1006 :
1007 : /// Two pairs are equal iff their members are equal.
1008 : template<typename _T1, typename _T2, typename _U1, typename _U2>
1009 : inline _GLIBCXX_CONSTEXPR bool
1010 : operator==(const pair<_T1, _T2>& __x, const pair<_U1, _U2>& __y)
1011 : { return __x.first == __y.first && __x.second == __y.second; }
1012 :
1013 : /** Defines a lexicographical order for pairs.
1014 : *
1015 : * For two pairs of comparable types, `P` is ordered before `Q` if
1016 : * `P.first` is less than `Q.first`, or if `P.first` and `Q.first`
1017 : * are equivalent (neither is less than the other) and `P.second` is
1018 : * less than `Q.second`.
1019 : */
1020 : template<typename _T1, typename _T2, typename _U1, typename _U2>
1021 : constexpr common_comparison_category_t<__detail::__synth3way_t<_T1, _U1>,
1022 : __detail::__synth3way_t<_T2, _U2>>
1023 : operator<=>(const pair<_T1, _T2>& __x, const pair<_U1, _U2>& __y)
1024 : {
1025 : if (auto __c = __detail::__synth3way(__x.first, __y.first); __c != 0)
1026 : return __c;
1027 : return __detail::__synth3way(__x.second, __y.second);
1028 : }
1029 : #else
1030 : /// Two pairs of the same type are equal iff their members are equal.
1031 : template<typename _T1, typename _T2>
1032 : inline _GLIBCXX_CONSTEXPR bool
1033 : operator==(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
1034 : { return __x.first == __y.first && __x.second == __y.second; }
1035 :
1036 : /** Defines a lexicographical order for pairs.
1037 : *
1038 : * For two pairs of the same type, `P` is ordered before `Q` if
1039 : * `P.first` is less than `Q.first`, or if `P.first` and `Q.first`
1040 : * are equivalent (neither is less than the other) and `P.second` is less
1041 : * than `Q.second`.
1042 : */
1043 : template<typename _T1, typename _T2>
1044 : inline _GLIBCXX_CONSTEXPR bool
1045 : operator<(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
1046 : { return __x.first < __y.first
1047 : || (!(__y.first < __x.first) && __x.second < __y.second); }
1048 :
1049 : /// Uses @c operator== to find the result.
1050 : template<typename _T1, typename _T2>
1051 : inline _GLIBCXX_CONSTEXPR bool
1052 : operator!=(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
1053 : { return !(__x == __y); }
1054 :
1055 : /// Uses @c operator< to find the result.
1056 : template<typename _T1, typename _T2>
1057 : inline _GLIBCXX_CONSTEXPR bool
1058 : operator>(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
1059 : { return __y < __x; }
1060 :
1061 : /// Uses @c operator< to find the result.
1062 : template<typename _T1, typename _T2>
1063 : inline _GLIBCXX_CONSTEXPR bool
1064 : operator<=(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
1065 : { return !(__y < __x); }
1066 :
1067 : /// Uses @c operator< to find the result.
1068 : template<typename _T1, typename _T2>
1069 : inline _GLIBCXX_CONSTEXPR bool
1070 : operator>=(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
1071 : { return !(__x < __y); }
1072 : #endif // !(three_way_comparison && concepts)
1073 :
1074 : #if __cplusplus >= 201103L
1075 : /** Swap overload for pairs. Calls std::pair::swap().
1076 : *
1077 : * @note This std::swap overload is not declared in C++03 mode,
1078 : * which has performance implications, e.g. see https://gcc.gnu.org/PR38466
1079 : */
1080 : template<typename _T1, typename _T2>
1081 : _GLIBCXX20_CONSTEXPR inline
1082 : #if __cplusplus > 201402L || !defined(__STRICT_ANSI__) // c++1z or gnu++11
1083 : // Constrained free swap overload, see p0185r1
1084 : typename enable_if<__and_<__is_swappable<_T1>,
1085 : __is_swappable<_T2>>::value>::type
1086 : #else
1087 : void
1088 : #endif
1089 : swap(pair<_T1, _T2>& __x, pair<_T1, _T2>& __y)
1090 : noexcept(noexcept(__x.swap(__y)))
1091 : { __x.swap(__y); }
1092 :
1093 : #if __glibcxx_ranges_zip // >= C++23
1094 : template<typename _T1, typename _T2>
1095 : requires is_swappable_v<const _T1> && is_swappable_v<const _T2>
1096 : constexpr void
1097 : swap(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
1098 : noexcept(noexcept(__x.swap(__y)))
1099 : { __x.swap(__y); }
1100 : #endif // C++23
1101 :
1102 : #if __cplusplus > 201402L || !defined(__STRICT_ANSI__) // c++1z or gnu++11
1103 : template<typename _T1, typename _T2>
1104 : typename enable_if<!__and_<__is_swappable<_T1>,
1105 : __is_swappable<_T2>>::value>::type
1106 : swap(pair<_T1, _T2>&, pair<_T1, _T2>&) = delete;
1107 : #endif
1108 : #endif // __cplusplus >= 201103L
1109 :
1110 : /// @} relates pair
1111 :
1112 : /**
1113 : * @brief A convenience wrapper for creating a pair from two objects.
1114 : * @param __x The first object.
1115 : * @param __y The second object.
1116 : * @return A newly-constructed pair<> object of the appropriate type.
1117 : *
1118 : * The C++98 standard says the objects are passed by reference-to-const,
1119 : * but C++03 says they are passed by value (this was LWG issue #181).
1120 : *
1121 : * Since C++11 they have been passed by forwarding reference and then
1122 : * forwarded to the new members of the pair. To create a pair with a
1123 : * member of reference type, pass a `reference_wrapper` to this function.
1124 : */
1125 : // _GLIBCXX_RESOLVE_LIB_DEFECTS
1126 : // 181. make_pair() unintended behavior
1127 : #if __cplusplus >= 201103L
1128 : // NB: DR 706.
1129 : template<typename _T1, typename _T2>
1130 : constexpr pair<typename __decay_and_strip<_T1>::__type,
1131 : typename __decay_and_strip<_T2>::__type>
1132 1081042 : make_pair(_T1&& __x, _T2&& __y)
1133 : {
1134 : typedef typename __decay_and_strip<_T1>::__type __ds_type1;
1135 : typedef typename __decay_and_strip<_T2>::__type __ds_type2;
1136 : typedef pair<__ds_type1, __ds_type2> __pair_type;
1137 1081042 : return __pair_type(std::forward<_T1>(__x), std::forward<_T2>(__y));
1138 : }
1139 : #else
1140 : template<typename _T1, typename _T2>
1141 : inline pair<_T1, _T2>
1142 : make_pair(_T1 __x, _T2 __y)
1143 : { return pair<_T1, _T2>(__x, __y); }
1144 : #endif
1145 :
1146 : /// @}
1147 :
1148 : #if __cplusplus >= 201103L
1149 : // Various functions which give std::pair a tuple-like interface.
1150 :
1151 : /// @cond undocumented
1152 : template<typename _T1, typename _T2>
1153 : struct __is_tuple_like_impl<pair<_T1, _T2>> : true_type
1154 : { };
1155 : /// @endcond
1156 :
1157 : /// Partial specialization for std::pair
1158 : template<class _Tp1, class _Tp2>
1159 : struct tuple_size<pair<_Tp1, _Tp2>>
1160 : : public integral_constant<size_t, 2> { };
1161 :
1162 : /// Partial specialization for std::pair
1163 : template<class _Tp1, class _Tp2>
1164 : struct tuple_element<0, pair<_Tp1, _Tp2>>
1165 : { typedef _Tp1 type; };
1166 :
1167 : /// Partial specialization for std::pair
1168 : template<class _Tp1, class _Tp2>
1169 : struct tuple_element<1, pair<_Tp1, _Tp2>>
1170 : { typedef _Tp2 type; };
1171 :
1172 : // Forward declare the partial specialization for std::tuple
1173 : // to work around modules bug PR c++/113814.
1174 : template<size_t __i, typename... _Types>
1175 : struct tuple_element<__i, tuple<_Types...>>;
1176 :
1177 : #if __cplusplus >= 201703L
1178 : template<typename _Tp1, typename _Tp2>
1179 : inline constexpr size_t tuple_size_v<pair<_Tp1, _Tp2>> = 2;
1180 :
1181 : template<typename _Tp1, typename _Tp2>
1182 : inline constexpr size_t tuple_size_v<const pair<_Tp1, _Tp2>> = 2;
1183 :
1184 : template<typename _Tp>
1185 : inline constexpr bool __is_pair = false;
1186 :
1187 : template<typename _Tp, typename _Up>
1188 : inline constexpr bool __is_pair<pair<_Tp, _Up>> = true;
1189 : #endif
1190 :
1191 : /// @cond undocumented
1192 : template<size_t _Int>
1193 : struct __pair_get;
1194 :
1195 : template<>
1196 : struct __pair_get<0>
1197 : {
1198 : template<typename _Tp1, typename _Tp2>
1199 : static constexpr _Tp1&
1200 : __get(pair<_Tp1, _Tp2>& __pair) noexcept
1201 : { return __pair.first; }
1202 :
1203 : template<typename _Tp1, typename _Tp2>
1204 : static constexpr _Tp1&&
1205 : __move_get(pair<_Tp1, _Tp2>&& __pair) noexcept
1206 : { return std::forward<_Tp1>(__pair.first); }
1207 :
1208 : template<typename _Tp1, typename _Tp2>
1209 : static constexpr const _Tp1&
1210 : __const_get(const pair<_Tp1, _Tp2>& __pair) noexcept
1211 : { return __pair.first; }
1212 :
1213 : template<typename _Tp1, typename _Tp2>
1214 : static constexpr const _Tp1&&
1215 : __const_move_get(const pair<_Tp1, _Tp2>&& __pair) noexcept
1216 : { return std::forward<const _Tp1>(__pair.first); }
1217 : };
1218 :
1219 : template<>
1220 : struct __pair_get<1>
1221 : {
1222 : template<typename _Tp1, typename _Tp2>
1223 : static constexpr _Tp2&
1224 : __get(pair<_Tp1, _Tp2>& __pair) noexcept
1225 : { return __pair.second; }
1226 :
1227 : template<typename _Tp1, typename _Tp2>
1228 : static constexpr _Tp2&&
1229 : __move_get(pair<_Tp1, _Tp2>&& __pair) noexcept
1230 : { return std::forward<_Tp2>(__pair.second); }
1231 :
1232 : template<typename _Tp1, typename _Tp2>
1233 : static constexpr const _Tp2&
1234 : __const_get(const pair<_Tp1, _Tp2>& __pair) noexcept
1235 : { return __pair.second; }
1236 :
1237 : template<typename _Tp1, typename _Tp2>
1238 : static constexpr const _Tp2&&
1239 : __const_move_get(const pair<_Tp1, _Tp2>&& __pair) noexcept
1240 : { return std::forward<const _Tp2>(__pair.second); }
1241 : };
1242 : /// @endcond
1243 :
1244 : /** @{
1245 : * std::get overloads for accessing members of std::pair
1246 : */
1247 :
1248 : template<size_t _Int, class _Tp1, class _Tp2>
1249 : constexpr typename tuple_element<_Int, pair<_Tp1, _Tp2>>::type&
1250 : get(pair<_Tp1, _Tp2>& __in) noexcept
1251 : { return __pair_get<_Int>::__get(__in); }
1252 :
1253 : template<size_t _Int, class _Tp1, class _Tp2>
1254 : constexpr typename tuple_element<_Int, pair<_Tp1, _Tp2>>::type&&
1255 : get(pair<_Tp1, _Tp2>&& __in) noexcept
1256 : { return __pair_get<_Int>::__move_get(std::move(__in)); }
1257 :
1258 : template<size_t _Int, class _Tp1, class _Tp2>
1259 : constexpr const typename tuple_element<_Int, pair<_Tp1, _Tp2>>::type&
1260 : get(const pair<_Tp1, _Tp2>& __in) noexcept
1261 : { return __pair_get<_Int>::__const_get(__in); }
1262 :
1263 : template<size_t _Int, class _Tp1, class _Tp2>
1264 : constexpr const typename tuple_element<_Int, pair<_Tp1, _Tp2>>::type&&
1265 : get(const pair<_Tp1, _Tp2>&& __in) noexcept
1266 : { return __pair_get<_Int>::__const_move_get(std::move(__in)); }
1267 :
1268 :
1269 : #ifdef __glibcxx_tuples_by_type // C++ >= 14
1270 : template <typename _Tp, typename _Up>
1271 : constexpr _Tp&
1272 : get(pair<_Tp, _Up>& __p) noexcept
1273 : { return __p.first; }
1274 :
1275 : template <typename _Tp, typename _Up>
1276 : constexpr const _Tp&
1277 : get(const pair<_Tp, _Up>& __p) noexcept
1278 : { return __p.first; }
1279 :
1280 : template <typename _Tp, typename _Up>
1281 : constexpr _Tp&&
1282 : get(pair<_Tp, _Up>&& __p) noexcept
1283 : { return std::move(__p.first); }
1284 :
1285 : template <typename _Tp, typename _Up>
1286 : constexpr const _Tp&&
1287 : get(const pair<_Tp, _Up>&& __p) noexcept
1288 : { return std::move(__p.first); }
1289 :
1290 : template <typename _Tp, typename _Up>
1291 : constexpr _Tp&
1292 : get(pair<_Up, _Tp>& __p) noexcept
1293 : { return __p.second; }
1294 :
1295 : template <typename _Tp, typename _Up>
1296 : constexpr const _Tp&
1297 : get(const pair<_Up, _Tp>& __p) noexcept
1298 : { return __p.second; }
1299 :
1300 : template <typename _Tp, typename _Up>
1301 : constexpr _Tp&&
1302 : get(pair<_Up, _Tp>&& __p) noexcept
1303 : { return std::move(__p.second); }
1304 :
1305 : template <typename _Tp, typename _Up>
1306 : constexpr const _Tp&&
1307 : get(const pair<_Up, _Tp>&& __p) noexcept
1308 : { return std::move(__p.second); }
1309 : #endif // __glibcxx_tuples_by_type
1310 :
1311 :
1312 : #if __glibcxx_ranges_zip // >= C++23
1313 : template<typename _T1, typename _T2, typename _U1, typename _U2,
1314 : template<typename> class _TQual, template<typename> class _UQual>
1315 : requires requires { typename pair<common_reference_t<_TQual<_T1>, _UQual<_U1>>,
1316 : common_reference_t<_TQual<_T2>, _UQual<_U2>>>; }
1317 : struct basic_common_reference<pair<_T1, _T2>, pair<_U1, _U2>, _TQual, _UQual>
1318 : {
1319 : using type = pair<common_reference_t<_TQual<_T1>, _UQual<_U1>>,
1320 : common_reference_t<_TQual<_T2>, _UQual<_U2>>>;
1321 : };
1322 :
1323 : template<typename _T1, typename _T2, typename _U1, typename _U2>
1324 : requires requires { typename pair<common_type_t<_T1, _U1>, common_type_t<_T2, _U2>>; }
1325 : struct common_type<pair<_T1, _T2>, pair<_U1, _U2>>
1326 : { using type = pair<common_type_t<_T1, _U1>, common_type_t<_T2, _U2>>; };
1327 : #endif // C++23
1328 :
1329 : /// @}
1330 : #endif // C++11
1331 :
1332 : _GLIBCXX_END_NAMESPACE_VERSION
1333 : } // namespace std
1334 :
1335 : #endif /* _STL_PAIR_H */
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