1// Pair implementation -*- C++ -*-
2
3// Copyright (C) 2001-2018 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
189#endif
190
191 /**
192 * @brief Struct holding two objects of arbitrary type.
193 *
194 * @tparam _T1 Type of first object.
195 * @tparam _T2 Type of second object.
196 */
197 template<typename _T1, typename _T2>
198 struct pair
199 {
200 typedef _T1 first_type; /// @c first_type is the first bound type
201 typedef _T2 second_type; /// @c second_type is the second bound type
202
203 _T1 first; /// @c first is a copy of the first object
204 _T2 second; /// @c second is a copy of the second object
205
206 // _GLIBCXX_RESOLVE_LIB_DEFECTS
207 // 265. std::pair::pair() effects overly restrictive
208 /** The default constructor creates @c first and @c second using their
209 * respective default constructors. */
210#if __cplusplus >= 201103L
211 template <typename _U1 = _T1,
212 typename _U2 = _T2,
213 typename enable_if<__and_<
214 __is_implicitly_default_constructible<_U1>,
215 __is_implicitly_default_constructible<_U2>>
216 ::value, bool>::type = true>
217#endif
218 _GLIBCXX_CONSTEXPR pair()
219 : first(), second() { }
220
221#if __cplusplus >= 201103L
222 template <typename _U1 = _T1,
223 typename _U2 = _T2,
224 typename enable_if<__and_<
225 is_default_constructible<_U1>,
226 is_default_constructible<_U2>,
227 __not_<
228 __and_<__is_implicitly_default_constructible<_U1>,
229 __is_implicitly_default_constructible<_U2>>>>
230 ::value, bool>::type = false>
231 explicit constexpr pair()
232 : first(), second() { }
233#endif
234
235 /** Two objects may be passed to a @c pair constructor to be copied. */
236#if __cplusplus < 201103L
237 pair(const _T1& __a, const _T2& __b)
238 : first(__a), second(__b) { }
239#else
240 // Shortcut for constraining the templates that don't take pairs.
241 using _PCCP = _PCC<true, _T1, _T2>;
242
243 template<typename _U1 = _T1, typename _U2=_T2, typename
244 enable_if<_PCCP::template
245 _ConstructiblePair<_U1, _U2>()
246 && _PCCP::template
247 _ImplicitlyConvertiblePair<_U1, _U2>(),
248 bool>::type=true>
249 constexpr pair(const _T1& __a, const _T2& __b)
250 : first(__a), second(__b) { }
251
252 template<typename _U1 = _T1, typename _U2=_T2, typename
253 enable_if<_PCCP::template
254 _ConstructiblePair<_U1, _U2>()
255 && !_PCCP::template
256 _ImplicitlyConvertiblePair<_U1, _U2>(),
257 bool>::type=false>
258 explicit constexpr pair(const _T1& __a, const _T2& __b)
259 : first(__a), second(__b) { }
260#endif
261
262 /** There is also a templated copy ctor for the @c pair class itself. */
263#if __cplusplus < 201103L
264 template<typename _U1, typename _U2>
265 pair(const pair<_U1, _U2>& __p)
266 : first(__p.first), second(__p.second) { }
267#else
268 // Shortcut for constraining the templates that take pairs.
269 template <typename _U1, typename _U2>
270 using _PCCFP = _PCC<!is_same<_T1, _U1>::value
271 || !is_same<_T2, _U2>::value,
272 _T1, _T2>;
273
274 template<typename _U1, typename _U2, typename
275 enable_if<_PCCFP<_U1, _U2>::template
276 _ConstructiblePair<_U1, _U2>()
277 && _PCCFP<_U1, _U2>::template
278 _ImplicitlyConvertiblePair<_U1, _U2>(),
279 bool>::type=true>
280 constexpr pair(const pair<_U1, _U2>& __p)
281 : first(__p.first), second(__p.second) { }
282
283 template<typename _U1, typename _U2, typename
284 enable_if<_PCCFP<_U1, _U2>::template
285 _ConstructiblePair<_U1, _U2>()
286 && !_PCCFP<_U1, _U2>::template
287 _ImplicitlyConvertiblePair<_U1, _U2>(),
288 bool>::type=false>
289 explicit constexpr pair(const pair<_U1, _U2>& __p)
290 : first(__p.first), second(__p.second) { }
291
292 constexpr pair(const pair&) = default;
293 constexpr pair(pair&&) = default;
294
295 // DR 811.
296 template<typename _U1, typename
297 enable_if<_PCCP::template
298 _MoveCopyPair<true, _U1, _T2>(),
299 bool>::type=true>
300 constexpr pair(_U1&& __x, const _T2& __y)
301 : first(std::forward<_U1>(__x)), second(__y) { }
302
303 template<typename _U1, typename
304 enable_if<_PCCP::template
305 _MoveCopyPair<false, _U1, _T2>(),
306 bool>::type=false>
307 explicit constexpr pair(_U1&& __x, const _T2& __y)
308 : first(std::forward<_U1>(__x)), second(__y) { }
309
310 template<typename _U2, typename
311 enable_if<_PCCP::template
312 _CopyMovePair<true, _T1, _U2>(),
313 bool>::type=true>
314 constexpr pair(const _T1& __x, _U2&& __y)
315 : first(__x), second(std::forward<_U2>(__y)) { }
316
317 template<typename _U2, typename
318 enable_if<_PCCP::template
319 _CopyMovePair<false, _T1, _U2>(),
320 bool>::type=false>
321 explicit pair(const _T1& __x, _U2&& __y)
322 : first(__x), second(std::forward<_U2>(__y)) { }
323
324 template<typename _U1, typename _U2, typename
325 enable_if<_PCCP::template
326 _MoveConstructiblePair<_U1, _U2>()
327 && _PCCP::template
328 _ImplicitlyMoveConvertiblePair<_U1, _U2>(),
329 bool>::type=true>
330 constexpr pair(_U1&& __x, _U2&& __y)
331 : first(std::forward<_U1>(__x)), second(std::forward<_U2>(__y)) { }
332
333 template<typename _U1, typename _U2, typename
334 enable_if<_PCCP::template
335 _MoveConstructiblePair<_U1, _U2>()
336 && !_PCCP::template
337 _ImplicitlyMoveConvertiblePair<_U1, _U2>(),
338 bool>::type=false>
339 explicit constexpr pair(_U1&& __x, _U2&& __y)
340 : first(std::forward<_U1>(__x)), second(std::forward<_U2>(__y)) { }
341
342
343 template<typename _U1, typename _U2, typename
344 enable_if<_PCCFP<_U1, _U2>::template
345 _MoveConstructiblePair<_U1, _U2>()
346 && _PCCFP<_U1, _U2>::template
347 _ImplicitlyMoveConvertiblePair<_U1, _U2>(),
348 bool>::type=true>
349 constexpr pair(pair<_U1, _U2>&& __p)
350 : first(std::forward<_U1>(__p.first)),
351 second(std::forward<_U2>(__p.second)) { }
352
353 template<typename _U1, typename _U2, typename
354 enable_if<_PCCFP<_U1, _U2>::template
355 _MoveConstructiblePair<_U1, _U2>()
356 && !_PCCFP<_U1, _U2>::template
357 _ImplicitlyMoveConvertiblePair<_U1, _U2>(),
358 bool>::type=false>
359 explicit constexpr pair(pair<_U1, _U2>&& __p)
360 : first(std::forward<_U1>(__p.first)),
361 second(std::forward<_U2>(__p.second)) { }
362
363 template<typename... _Args1, typename... _Args2>
364 pair(piecewise_construct_t, tuple<_Args1...>, tuple<_Args2...>);
365
366 pair&
367 operator=(typename conditional<
368 __and_<is_copy_assignable<_T1>,
369 is_copy_assignable<_T2>>::value,
370 const pair&, const __nonesuch_no_braces&>::type __p)
371 {
372 first = __p.first;
373 second = __p.second;
374 return *this;
375 }
376
377 pair&
378 operator=(typename conditional<
379 __not_<__and_<is_copy_assignable<_T1>,
380 is_copy_assignable<_T2>>>::value,
381 const pair&, const __nonesuch_no_braces&>::type __p) = delete;
382
383 pair&
384 operator=(typename conditional<
385 __and_<is_move_assignable<_T1>,
386 is_move_assignable<_T2>>::value,
387 pair&&, __nonesuch_no_braces&&>::type __p)
388 noexcept(__and_<is_nothrow_move_assignable<_T1>,
389 is_nothrow_move_assignable<_T2>>::value)
390 {
391 first = std::forward<first_type>(__p.first);
392 second = std::forward<second_type>(__p.second);
393 return *this;
394 }
395
396 template<typename _U1, typename _U2>
397 typename enable_if<__and_<is_assignable<_T1&, const _U1&>,
398 is_assignable<_T2&, const _U2&>>::value,
399 pair&>::type
400 operator=(const pair<_U1, _U2>& __p)
401 {
402 first = __p.first;
403 second = __p.second;
404 return *this;
405 }
406
407 template<typename _U1, typename _U2>
408 typename enable_if<__and_<is_assignable<_T1&, _U1&&>,
409 is_assignable<_T2&, _U2&&>>::value,
410 pair&>::type
411 operator=(pair<_U1, _U2>&& __p)
412 {
413 first = std::forward<_U1>(__p.first);
414 second = std::forward<_U2>(__p.second);
415 return *this;
416 }
417
418 void
419 swap(pair& __p)
420 noexcept(__and_<__is_nothrow_swappable<_T1>,
421 __is_nothrow_swappable<_T2>>::value)
422 {
423 using std::swap;
424 swap(first, __p.first);
425 swap(second, __p.second);
426 }
427
428 private:
429 template<typename... _Args1, std::size_t... _Indexes1,
430 typename... _Args2, std::size_t... _Indexes2>
431 pair(tuple<_Args1...>&, tuple<_Args2...>&,
432 _Index_tuple<_Indexes1...>, _Index_tuple<_Indexes2...>);
433#endif
434 };
435
436#if __cpp_deduction_guides >= 201606
437 template<typename _T1, typename _T2> pair(_T1, _T2) -> pair<_T1, _T2>;
438#endif
439
440 /// Two pairs of the same type are equal iff their members are equal.
441 template<typename _T1, typename _T2>
442 inline _GLIBCXX_CONSTEXPR bool
443 operator==(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
444 { return __x.first == __y.first && __x.second == __y.second; }
445
446 /// <http://gcc.gnu.org/onlinedocs/libstdc++/manual/utilities.html>
447 template<typename _T1, typename _T2>
448 inline _GLIBCXX_CONSTEXPR bool
449 operator<(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
450 { return __x.first < __y.first
451 || (!(__y.first < __x.first) && __x.second < __y.second); }
452
453 /// Uses @c operator== to find the result.
454 template<typename _T1, typename _T2>
455 inline _GLIBCXX_CONSTEXPR bool
456 operator!=(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
457 { return !(__x == __y); }
458
459 /// Uses @c operator< to find the result.
460 template<typename _T1, typename _T2>
461 inline _GLIBCXX_CONSTEXPR bool
462 operator>(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
463 { return __y < __x; }
464
465 /// Uses @c operator< to find the result.
466 template<typename _T1, typename _T2>
467 inline _GLIBCXX_CONSTEXPR bool
468 operator<=(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
469 { return !(__y < __x); }
470
471 /// Uses @c operator< to find the result.
472 template<typename _T1, typename _T2>
473 inline _GLIBCXX_CONSTEXPR bool
474 operator>=(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
475 { return !(__x < __y); }
476
477#if __cplusplus >= 201103L
478 /// See std::pair::swap().
479 // Note: no std::swap overloads in C++03 mode, this has performance
480 // implications, see, eg, libstdc++/38466.
481 template<typename _T1, typename _T2>
482 inline
483#if __cplusplus > 201402L || !defined(__STRICT_ANSI__) // c++1z or gnu++11
484 // Constrained free swap overload, see p0185r1
485 typename enable_if<__and_<__is_swappable<_T1>,
486 __is_swappable<_T2>>::value>::type
487#else
488 void
489#endif
490 swap(pair<_T1, _T2>& __x, pair<_T1, _T2>& __y)
491 noexcept(noexcept(__x.swap(__y)))
492 { __x.swap(__y); }
493
494#if __cplusplus > 201402L || !defined(__STRICT_ANSI__) // c++1z or gnu++11
495 template<typename _T1, typename _T2>
496 typename enable_if<!__and_<__is_swappable<_T1>,
497 __is_swappable<_T2>>::value>::type
498 swap(pair<_T1, _T2>&, pair<_T1, _T2>&) = delete;
499#endif
500#endif // __cplusplus >= 201103L
501
502 /**
503 * @brief A convenience wrapper for creating a pair from two objects.
504 * @param __x The first object.
505 * @param __y The second object.
506 * @return A newly-constructed pair<> object of the appropriate type.
507 *
508 * The standard requires that the objects be passed by reference-to-const,
509 * but LWG issue #181 says they should be passed by const value. We follow
510 * the LWG by default.
511 */
512 // _GLIBCXX_RESOLVE_LIB_DEFECTS
513 // 181. make_pair() unintended behavior
514#if __cplusplus >= 201103L
515 // NB: DR 706.
516 template<typename _T1, typename _T2>
517 constexpr pair<typename __decay_and_strip<_T1>::__type,
518 typename __decay_and_strip<_T2>::__type>
519 make_pair(_T1&& __x, _T2&& __y)
520 {
521 typedef typename __decay_and_strip<_T1>::__type __ds_type1;
522 typedef typename __decay_and_strip<_T2>::__type __ds_type2;
523 typedef pair<__ds_type1, __ds_type2> __pair_type;
524 return __pair_type(std::forward<_T1>(__x), std::forward<_T2>(__y));
525 }
526#else
527 template<typename _T1, typename _T2>
528 inline pair<_T1, _T2>
529 make_pair(_T1 __x, _T2 __y)
530 { return pair<_T1, _T2>(__x, __y); }
531#endif
532
533 /// @}
534
535_GLIBCXX_END_NAMESPACE_VERSION
536} // namespace std
537
538#endif /* _STL_PAIR_H */
539