1// Pair implementation -*- C++ -*-
2
3// Copyright (C) 2001-2019 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#include <bits/move.h> // for std::move / std::forward, and std::swap
60
61#if __cplusplus >= 201103L
62#include <type_traits> // for std::__decay_and_strip too
63#endif
64
65namespace std _GLIBCXX_VISIBILITY(default)
66{
67_GLIBCXX_BEGIN_NAMESPACE_VERSION
68
69 /**
70 * @addtogroup utilities
71 * @{
72 */
73
74#if __cplusplus >= 201103L
75 /// piecewise_construct_t
76 struct piecewise_construct_t { explicit piecewise_construct_t() = default; };
77
78 /// piecewise_construct
79 _GLIBCXX17_INLINE constexpr piecewise_construct_t piecewise_construct =
80 piecewise_construct_t();
81
82 // Forward declarations.
83 template<typename...>
84 class tuple;
85
86 template<std::size_t...>
87 struct _Index_tuple;
88
89 // Concept utility functions, reused in conditionally-explicit
90 // constructors.
91 // See PR 70437, don't look at is_constructible or
92 // is_convertible if the types are the same to
93 // avoid querying those properties for incomplete types.
94 template <bool, typename _T1, typename _T2>
95 struct _PCC
96 {
97 template <typename _U1, typename _U2>
98 static constexpr bool _ConstructiblePair()
99 {
100 return __and_<is_constructible<_T1, const _U1&>,
101 is_constructible<_T2, const _U2&>>::value;
102 }
103
104 template <typename _U1, typename _U2>
105 static constexpr bool _ImplicitlyConvertiblePair()
106 {
107 return __and_<is_convertible<const _U1&, _T1>,
108 is_convertible<const _U2&, _T2>>::value;
109 }
110
111 template <typename _U1, typename _U2>
112 static constexpr bool _MoveConstructiblePair()
113 {
114 return __and_<is_constructible<_T1, _U1&&>,
115 is_constructible<_T2, _U2&&>>::value;
116 }
117
118 template <typename _U1, typename _U2>
119 static constexpr bool _ImplicitlyMoveConvertiblePair()
120 {
121 return __and_<is_convertible<_U1&&, _T1>,
122 is_convertible<_U2&&, _T2>>::value;
123 }
124
125 template <bool __implicit, typename _U1, typename _U2>
126 static constexpr bool _CopyMovePair()
127 {
128 using __do_converts = __and_<is_convertible<const _U1&, _T1>,
129 is_convertible<_U2&&, _T2>>;
130 using __converts = typename conditional<__implicit,
131 __do_converts,
132 __not_<__do_converts>>::type;
133 return __and_<is_constructible<_T1, const _U1&>,
134 is_constructible<_T2, _U2&&>,
135 __converts
136 >::value;
137 }
138
139 template <bool __implicit, typename _U1, typename _U2>
140 static constexpr bool _MoveCopyPair()
141 {
142 using __do_converts = __and_<is_convertible<_U1&&, _T1>,
143 is_convertible<const _U2&, _T2>>;
144 using __converts = typename conditional<__implicit,
145 __do_converts,
146 __not_<__do_converts>>::type;
147 return __and_<is_constructible<_T1, _U1&&>,
148 is_constructible<_T2, const _U2&&>,
149 __converts
150 >::value;
151 }
152 };
153
154 template <typename _T1, typename _T2>
155 struct _PCC<false, _T1, _T2>
156 {
157 template <typename _U1, typename _U2>
158 static constexpr bool _ConstructiblePair()
159 {
160 return false;
161 }
162
163 template <typename _U1, typename _U2>
164 static constexpr bool _ImplicitlyConvertiblePair()
165 {
166 return false;
167 }
168
169 template <typename _U1, typename _U2>
170 static constexpr bool _MoveConstructiblePair()
171 {
172 return false;
173 }
174
175 template <typename _U1, typename _U2>
176 static constexpr bool _ImplicitlyMoveConvertiblePair()
177 {
178 return false;
179 }
180 };
181
182 // PR libstdc++/79141, a utility type for preventing
183 // initialization of an argument of a disabled assignment
184 // operator from a pair of empty braces.
185 struct __nonesuch_no_braces : std::__nonesuch {
186 explicit __nonesuch_no_braces(const __nonesuch&) = delete;
187 };
188#endif // C++11
189
190 template<typename _U1, typename _U2> class __pair_base
191 {
192#if __cplusplus >= 201103L
193 template<typename _T1, typename _T2> friend struct pair;
194 __pair_base() = default;
195 ~__pair_base() = default;
196 __pair_base(const __pair_base&) = default;
197 __pair_base& operator=(const __pair_base&) = delete;
198#endif // C++11
199 };
200
201 /**
202 * @brief Struct holding two objects of arbitrary type.
203 *
204 * @tparam _T1 Type of first object.
205 * @tparam _T2 Type of second object.
206 */
207 template<typename _T1, typename _T2>
208 struct pair
209 : private __pair_base<_T1, _T2>
210 {
211 typedef _T1 first_type; /// @c first_type is the first bound type
212 typedef _T2 second_type; /// @c second_type is the second bound type
213
214 _T1 first; /// @c first is a copy of the first object
215 _T2 second; /// @c second is a copy of the second object
216
217 // _GLIBCXX_RESOLVE_LIB_DEFECTS
218 // 265. std::pair::pair() effects overly restrictive
219 /** The default constructor creates @c first and @c second using their
220 * respective default constructors. */
221#if __cplusplus >= 201103L
222 template <typename _U1 = _T1,
223 typename _U2 = _T2,
224 typename enable_if<__and_<
225 __is_implicitly_default_constructible<_U1>,
226 __is_implicitly_default_constructible<_U2>>
227 ::value, bool>::type = true>
228#endif
229 _GLIBCXX_CONSTEXPR pair()
230 : first(), second() { }
231
232#if __cplusplus >= 201103L
233 template <typename _U1 = _T1,
234 typename _U2 = _T2,
235 typename enable_if<__and_<
236 is_default_constructible<_U1>,
237 is_default_constructible<_U2>,
238 __not_<
239 __and_<__is_implicitly_default_constructible<_U1>,
240 __is_implicitly_default_constructible<_U2>>>>
241 ::value, bool>::type = false>
242 explicit constexpr pair()
243 : first(), second() { }
244#endif
245
246 /** Two objects may be passed to a @c pair constructor to be copied. */
247#if __cplusplus < 201103L
248 pair(const _T1& __a, const _T2& __b)
249 : first(__a), second(__b) { }
250#else
251 // Shortcut for constraining the templates that don't take pairs.
252 using _PCCP = _PCC<true, _T1, _T2>;
253
254 template<typename _U1 = _T1, typename _U2=_T2, typename
255 enable_if<_PCCP::template
256 _ConstructiblePair<_U1, _U2>()
257 && _PCCP::template
258 _ImplicitlyConvertiblePair<_U1, _U2>(),
259 bool>::type=true>
260 constexpr pair(const _T1& __a, const _T2& __b)
261 : first(__a), second(__b) { }
262
263 template<typename _U1 = _T1, typename _U2=_T2, typename
264 enable_if<_PCCP::template
265 _ConstructiblePair<_U1, _U2>()
266 && !_PCCP::template
267 _ImplicitlyConvertiblePair<_U1, _U2>(),
268 bool>::type=false>
269 explicit constexpr pair(const _T1& __a, const _T2& __b)
270 : first(__a), second(__b) { }
271#endif
272
273 /** There is also a templated copy ctor for the @c pair class itself. */
274#if __cplusplus < 201103L
275 template<typename _U1, typename _U2>
276 pair(const pair<_U1, _U2>& __p)
277 : first(__p.first), second(__p.second) { }
278#else
279 // Shortcut for constraining the templates that take pairs.
280 template <typename _U1, typename _U2>
281 using _PCCFP = _PCC<!is_same<_T1, _U1>::value
282 || !is_same<_T2, _U2>::value,
283 _T1, _T2>;
284
285 template<typename _U1, typename _U2, typename
286 enable_if<_PCCFP<_U1, _U2>::template
287 _ConstructiblePair<_U1, _U2>()
288 && _PCCFP<_U1, _U2>::template
289 _ImplicitlyConvertiblePair<_U1, _U2>(),
290 bool>::type=true>
291 constexpr pair(const pair<_U1, _U2>& __p)
292 : first(__p.first), second(__p.second) { }
293
294 template<typename _U1, typename _U2, typename
295 enable_if<_PCCFP<_U1, _U2>::template
296 _ConstructiblePair<_U1, _U2>()
297 && !_PCCFP<_U1, _U2>::template
298 _ImplicitlyConvertiblePair<_U1, _U2>(),
299 bool>::type=false>
300 explicit constexpr pair(const pair<_U1, _U2>& __p)
301 : first(__p.first), second(__p.second) { }
302
303 constexpr pair(const pair&) = default;
304 constexpr pair(pair&&) = default;
305
306 // DR 811.
307 template<typename _U1, typename
308 enable_if<_PCCP::template
309 _MoveCopyPair<true, _U1, _T2>(),
310 bool>::type=true>
311 constexpr pair(_U1&& __x, const _T2& __y)
312 : first(std::forward<_U1>(__x)), second(__y) { }
313
314 template<typename _U1, typename
315 enable_if<_PCCP::template
316 _MoveCopyPair<false, _U1, _T2>(),
317 bool>::type=false>
318 explicit constexpr pair(_U1&& __x, const _T2& __y)
319 : first(std::forward<_U1>(__x)), second(__y) { }
320
321 template<typename _U2, typename
322 enable_if<_PCCP::template
323 _CopyMovePair<true, _T1, _U2>(),
324 bool>::type=true>
325 constexpr pair(const _T1& __x, _U2&& __y)
326 : first(__x), second(std::forward<_U2>(__y)) { }
327
328 template<typename _U2, typename
329 enable_if<_PCCP::template
330 _CopyMovePair<false, _T1, _U2>(),
331 bool>::type=false>
332 explicit pair(const _T1& __x, _U2&& __y)
333 : first(__x), second(std::forward<_U2>(__y)) { }
334
335 template<typename _U1, typename _U2, typename
336 enable_if<_PCCP::template
337 _MoveConstructiblePair<_U1, _U2>()
338 && _PCCP::template
339 _ImplicitlyMoveConvertiblePair<_U1, _U2>(),
340 bool>::type=true>
341 constexpr pair(_U1&& __x, _U2&& __y)
342 : first(std::forward<_U1>(__x)), second(std::forward<_U2>(__y)) { }
343
344 template<typename _U1, typename _U2, typename
345 enable_if<_PCCP::template
346 _MoveConstructiblePair<_U1, _U2>()
347 && !_PCCP::template
348 _ImplicitlyMoveConvertiblePair<_U1, _U2>(),
349 bool>::type=false>
350 explicit constexpr pair(_U1&& __x, _U2&& __y)
351 : first(std::forward<_U1>(__x)), second(std::forward<_U2>(__y)) { }
352
353
354 template<typename _U1, typename _U2, typename
355 enable_if<_PCCFP<_U1, _U2>::template
356 _MoveConstructiblePair<_U1, _U2>()
357 && _PCCFP<_U1, _U2>::template
358 _ImplicitlyMoveConvertiblePair<_U1, _U2>(),
359 bool>::type=true>
360 constexpr pair(pair<_U1, _U2>&& __p)
361 : first(std::forward<_U1>(__p.first)),
362 second(std::forward<_U2>(__p.second)) { }
363
364 template<typename _U1, typename _U2, typename
365 enable_if<_PCCFP<_U1, _U2>::template
366 _MoveConstructiblePair<_U1, _U2>()
367 && !_PCCFP<_U1, _U2>::template
368 _ImplicitlyMoveConvertiblePair<_U1, _U2>(),
369 bool>::type=false>
370 explicit constexpr pair(pair<_U1, _U2>&& __p)
371 : first(std::forward<_U1>(__p.first)),
372 second(std::forward<_U2>(__p.second)) { }
373
374 template<typename... _Args1, typename... _Args2>
375 pair(piecewise_construct_t, tuple<_Args1...>, tuple<_Args2...>);
376
377 pair&
378 operator=(typename conditional<
379 __and_<is_copy_assignable<_T1>,
380 is_copy_assignable<_T2>>::value,
381 const pair&, const __nonesuch_no_braces&>::type __p)
382 {
383 first = __p.first;
384 second = __p.second;
385 return *this;
386 }
387
388 pair&
389 operator=(typename conditional<
390 __and_<is_move_assignable<_T1>,
391 is_move_assignable<_T2>>::value,
392 pair&&, __nonesuch_no_braces&&>::type __p)
393 noexcept(__and_<is_nothrow_move_assignable<_T1>,
394 is_nothrow_move_assignable<_T2>>::value)
395 {
396 first = std::forward<first_type>(__p.first);
397 second = std::forward<second_type>(__p.second);
398 return *this;
399 }
400
401 template<typename _U1, typename _U2>
402 typename enable_if<__and_<is_assignable<_T1&, const _U1&>,
403 is_assignable<_T2&, const _U2&>>::value,
404 pair&>::type
405 operator=(const pair<_U1, _U2>& __p)
406 {
407 first = __p.first;
408 second = __p.second;
409 return *this;
410 }
411
412 template<typename _U1, typename _U2>
413 typename enable_if<__and_<is_assignable<_T1&, _U1&&>,
414 is_assignable<_T2&, _U2&&>>::value,
415 pair&>::type
416 operator=(pair<_U1, _U2>&& __p)
417 {
418 first = std::forward<_U1>(__p.first);
419 second = std::forward<_U2>(__p.second);
420 return *this;
421 }
422
423 void
424 swap(pair& __p)
425 noexcept(__and_<__is_nothrow_swappable<_T1>,
426 __is_nothrow_swappable<_T2>>::value)
427 {
428 using std::swap;
429 swap(first, __p.first);
430 swap(second, __p.second);
431 }
432
433 private:
434 template<typename... _Args1, std::size_t... _Indexes1,
435 typename... _Args2, std::size_t... _Indexes2>
436 pair(tuple<_Args1...>&, tuple<_Args2...>&,
437 _Index_tuple<_Indexes1...>, _Index_tuple<_Indexes2...>);
438#endif
439 };
440
441#if __cpp_deduction_guides >= 201606
442 template<typename _T1, typename _T2> pair(_T1, _T2) -> pair<_T1, _T2>;
443#endif
444
445 /// Two pairs of the same type are equal iff their members are equal.
446 template<typename _T1, typename _T2>
447 inline _GLIBCXX_CONSTEXPR bool
448 operator==(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
449 { return __x.first == __y.first && __x.second == __y.second; }
450
451 /// <http://gcc.gnu.org/onlinedocs/libstdc++/manual/utilities.html>
452 template<typename _T1, typename _T2>
453 inline _GLIBCXX_CONSTEXPR bool
454 operator<(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
455 { return __x.first < __y.first
456 || (!(__y.first < __x.first) && __x.second < __y.second); }
457
458 /// Uses @c operator== to find the result.
459 template<typename _T1, typename _T2>
460 inline _GLIBCXX_CONSTEXPR bool
461 operator!=(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
462 { return !(__x == __y); }
463
464 /// Uses @c operator< to find the result.
465 template<typename _T1, typename _T2>
466 inline _GLIBCXX_CONSTEXPR bool
467 operator>(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
468 { return __y < __x; }
469
470 /// Uses @c operator< to find the result.
471 template<typename _T1, typename _T2>
472 inline _GLIBCXX_CONSTEXPR bool
473 operator<=(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
474 { return !(__y < __x); }
475
476 /// Uses @c operator< to find the result.
477 template<typename _T1, typename _T2>
478 inline _GLIBCXX_CONSTEXPR bool
479 operator>=(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
480 { return !(__x < __y); }
481
482#if __cplusplus >= 201103L
483 /// See std::pair::swap().
484 // Note: no std::swap overloads in C++03 mode, this has performance
485 // implications, see, eg, libstdc++/38466.
486 template<typename _T1, typename _T2>
487 inline
488#if __cplusplus > 201402L || !defined(__STRICT_ANSI__) // c++1z or gnu++11
489 // Constrained free swap overload, see p0185r1
490 typename enable_if<__and_<__is_swappable<_T1>,
491 __is_swappable<_T2>>::value>::type
492#else
493 void
494#endif
495 swap(pair<_T1, _T2>& __x, pair<_T1, _T2>& __y)
496 noexcept(noexcept(__x.swap(__y)))
497 { __x.swap(__y); }
498
499#if __cplusplus > 201402L || !defined(__STRICT_ANSI__) // c++1z or gnu++11
500 template<typename _T1, typename _T2>
501 typename enable_if<!__and_<__is_swappable<_T1>,
502 __is_swappable<_T2>>::value>::type
503 swap(pair<_T1, _T2>&, pair<_T1, _T2>&) = delete;
504#endif
505#endif // __cplusplus >= 201103L
506
507 /**
508 * @brief A convenience wrapper for creating a pair from two objects.
509 * @param __x The first object.
510 * @param __y The second object.
511 * @return A newly-constructed pair<> object of the appropriate type.
512 *
513 * The standard requires that the objects be passed by reference-to-const,
514 * but LWG issue #181 says they should be passed by const value. We follow
515 * the LWG by default.
516 */
517 // _GLIBCXX_RESOLVE_LIB_DEFECTS
518 // 181. make_pair() unintended behavior
519#if __cplusplus >= 201103L
520 // NB: DR 706.
521 template<typename _T1, typename _T2>
522 constexpr pair<typename __decay_and_strip<_T1>::__type,
523 typename __decay_and_strip<_T2>::__type>
524 make_pair(_T1&& __x, _T2&& __y)
525 {
526 typedef typename __decay_and_strip<_T1>::__type __ds_type1;
527 typedef typename __decay_and_strip<_T2>::__type __ds_type2;
528 typedef pair<__ds_type1, __ds_type2> __pair_type;
529 return __pair_type(std::forward<_T1>(__x), std::forward<_T2>(__y));
530 }
531#else
532 template<typename _T1, typename _T2>
533 inline pair<_T1, _T2>
534 make_pair(_T1 __x, _T2 __y)
535 { return pair<_T1, _T2>(__x, __y); }
536#endif
537
538 /// @}
539
540_GLIBCXX_END_NAMESPACE_VERSION
541} // namespace std
542
543#endif /* _STL_PAIR_H */
544