1// Pair implementation -*- C++ -*-
2
3// Copyright (C) 2001-2016 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 constexpr piecewise_construct_t piecewise_construct = piecewise_construct_t();
80
81 // Forward declarations.
82 template<typename...>
83 class tuple;
84
85 template<std::size_t...>
86 struct _Index_tuple;
87
88 // Concept utility functions, reused in conditionally-explicit
89 // constructors.
90 // See PR 70437, don't look at is_constructible or
91 // is_convertible if the types are the same to
92 // avoid querying those properties for incomplete types.
93 template <bool, typename _T1, typename _T2>
94 struct _PCC
95 {
96 template <typename _U1, typename _U2>
97 static constexpr bool _ConstructiblePair()
98 {
99 return __and_<is_constructible<_T1, const _U1&>,
100 is_constructible<_T2, const _U2&>>::value;
101 }
102
103 template <typename _U1, typename _U2>
104 static constexpr bool _ImplicitlyConvertiblePair()
105 {
106 return __and_<is_convertible<const _U1&, _T1>,
107 is_convertible<const _U2&, _T2>>::value;
108 }
109
110 template <typename _U1, typename _U2>
111 static constexpr bool _MoveConstructiblePair()
112 {
113 return __and_<is_constructible<_T1, _U1&&>,
114 is_constructible<_T2, _U2&&>>::value;
115 }
116
117 template <typename _U1, typename _U2>
118 static constexpr bool _ImplicitlyMoveConvertiblePair()
119 {
120 return __and_<is_convertible<_U1&&, _T1>,
121 is_convertible<_U2&&, _T2>>::value;
122 }
123
124 template <bool __implicit, typename _U1, typename _U2>
125 static constexpr bool _CopyMovePair()
126 {
127 using __do_converts = __and_<is_convertible<const _U1&, _T1>,
128 is_convertible<_U2&&, _T2>>;
129 using __converts = typename conditional<__implicit,
130 __do_converts,
131 __not_<__do_converts>>::type;
132 return __and_<is_constructible<_T1, const _U1&>,
133 is_constructible<_T2, _U2&&>,
134 __converts
135 >::value;
136 }
137
138 template <bool __implicit, typename _U1, typename _U2>
139 static constexpr bool _MoveCopyPair()
140 {
141 using __do_converts = __and_<is_convertible<_U1&&, _T1>,
142 is_convertible<const _U2&, _T2>>;
143 using __converts = typename conditional<__implicit,
144 __do_converts,
145 __not_<__do_converts>>::type;
146 return __and_<is_constructible<_T1, _U1&&>,
147 is_constructible<_T2, const _U2&&>,
148 __converts
149 >::value;
150 }
151 };
152
153 template <typename _T1, typename _T2>
154 struct _PCC<false, _T1, _T2>
155 {
156 template <typename _U1, typename _U2>
157 static constexpr bool _ConstructiblePair()
158 {
159 return false;
160 }
161
162 template <typename _U1, typename _U2>
163 static constexpr bool _ImplicitlyConvertiblePair()
164 {
165 return false;
166 }
167
168 template <typename _U1, typename _U2>
169 static constexpr bool _MoveConstructiblePair()
170 {
171 return false;
172 }
173
174 template <typename _U1, typename _U2>
175 static constexpr bool _ImplicitlyMoveConvertiblePair()
176 {
177 return false;
178 }
179 };
180
181 struct __wrap_nonesuch : std::__nonesuch {
182 explicit __wrap_nonesuch(const __nonesuch&) = delete;
183 };
184
185#endif
186
187 /**
188 * @brief Struct holding two objects of arbitrary type.
189 *
190 * @tparam _T1 Type of first object.
191 * @tparam _T2 Type of second object.
192 */
193 template<typename _T1, typename _T2>
194 struct pair
195 {
196 typedef _T1 first_type; /// @c first_type is the first bound type
197 typedef _T2 second_type; /// @c second_type is the second bound type
198
199 _T1 first; /// @c first is a copy of the first object
200 _T2 second; /// @c second is a copy of the second object
201
202 // _GLIBCXX_RESOLVE_LIB_DEFECTS
203 // 265. std::pair::pair() effects overly restrictive
204 /** The default constructor creates @c first and @c second using their
205 * respective default constructors. */
206#if __cplusplus >= 201103L
207 template <typename _U1 = _T1,
208 typename _U2 = _T2,
209 typename enable_if<__and_<
210 __is_implicitly_default_constructible<_U1>,
211 __is_implicitly_default_constructible<_U2>>
212 ::value, bool>::type = true>
213#endif
214 _GLIBCXX_CONSTEXPR pair()
215 : first(), second() { }
216
217#if __cplusplus >= 201103L
218 template <typename _U1 = _T1,
219 typename _U2 = _T2,
220 typename enable_if<__and_<
221 is_default_constructible<_U1>,
222 is_default_constructible<_U2>,
223 __not_<
224 __and_<__is_implicitly_default_constructible<_U1>,
225 __is_implicitly_default_constructible<_U2>>>>
226 ::value, bool>::type = false>
227 explicit constexpr pair()
228 : first(), second() { }
229#endif
230
231 /** Two objects may be passed to a @c pair constructor to be copied. */
232#if __cplusplus < 201103L
233 pair(const _T1& __a, const _T2& __b)
234 : first(__a), second(__b) { }
235#else
236 // Shortcut for constraining the templates that don't take pairs.
237 using _PCCP = _PCC<true, _T1, _T2>;
238
239 template<typename _U1 = _T1, typename _U2=_T2, typename
240 enable_if<_PCCP::template
241 _ConstructiblePair<_U1, _U2>()
242 && _PCCP::template
243 _ImplicitlyConvertiblePair<_U1, _U2>(),
244 bool>::type=true>
245 constexpr pair(const _T1& __a, const _T2& __b)
246 : first(__a), second(__b) { }
247
248 template<typename _U1 = _T1, typename _U2=_T2, typename
249 enable_if<_PCCP::template
250 _ConstructiblePair<_U1, _U2>()
251 && !_PCCP::template
252 _ImplicitlyConvertiblePair<_U1, _U2>(),
253 bool>::type=false>
254 explicit constexpr pair(const _T1& __a, const _T2& __b)
255 : first(__a), second(__b) { }
256#endif
257
258 /** There is also a templated copy ctor for the @c pair class itself. */
259#if __cplusplus < 201103L
260 template<typename _U1, typename _U2>
261 pair(const pair<_U1, _U2>& __p)
262 : first(__p.first), second(__p.second) { }
263#else
264 // Shortcut for constraining the templates that take pairs.
265 template <typename _U1, typename _U2>
266 using _PCCFP = _PCC<!is_same<_T1, _U1>::value
267 || !is_same<_T2, _U2>::value,
268 _T1, _T2>;
269
270 template<typename _U1, typename _U2, typename
271 enable_if<_PCCFP<_U1, _U2>::template
272 _ConstructiblePair<_U1, _U2>()
273 && _PCCFP<_U1, _U2>::template
274 _ImplicitlyConvertiblePair<_U1, _U2>(),
275 bool>::type=true>
276 constexpr pair(const pair<_U1, _U2>& __p)
277 : first(__p.first), second(__p.second) { }
278
279 template<typename _U1, typename _U2, typename
280 enable_if<_PCCFP<_U1, _U2>::template
281 _ConstructiblePair<_U1, _U2>()
282 && !_PCCFP<_U1, _U2>::template
283 _ImplicitlyConvertiblePair<_U1, _U2>(),
284 bool>::type=false>
285 explicit constexpr pair(const pair<_U1, _U2>& __p)
286 : first(__p.first), second(__p.second) { }
287
288 constexpr pair(const pair&) = default;
289 constexpr pair(pair&&) = default;
290
291 // DR 811.
292 template<typename _U1, typename
293 enable_if<_PCCP::template
294 _MoveCopyPair<true, _U1, _T2>(),
295 bool>::type=true>
296 constexpr pair(_U1&& __x, const _T2& __y)
297 : first(std::forward<_U1>(__x)), second(__y) { }
298
299 template<typename _U1, typename
300 enable_if<_PCCP::template
301 _MoveCopyPair<false, _U1, _T2>(),
302 bool>::type=false>
303 explicit constexpr pair(_U1&& __x, const _T2& __y)
304 : first(std::forward<_U1>(__x)), second(__y) { }
305
306 template<typename _U2, typename
307 enable_if<_PCCP::template
308 _CopyMovePair<true, _T1, _U2>(),
309 bool>::type=true>
310 constexpr pair(const _T1& __x, _U2&& __y)
311 : first(__x), second(std::forward<_U2>(__y)) { }
312
313 template<typename _U2, typename
314 enable_if<_PCCP::template
315 _CopyMovePair<false, _T1, _U2>(),
316 bool>::type=false>
317 explicit pair(const _T1& __x, _U2&& __y)
318 : first(__x), second(std::forward<_U2>(__y)) { }
319
320 template<typename _U1, typename _U2, typename
321 enable_if<_PCCP::template
322 _MoveConstructiblePair<_U1, _U2>()
323 && _PCCP::template
324 _ImplicitlyMoveConvertiblePair<_U1, _U2>(),
325 bool>::type=true>
326 constexpr pair(_U1&& __x, _U2&& __y)
327 : first(std::forward<_U1>(__x)), second(std::forward<_U2>(__y)) { }
328
329 template<typename _U1, typename _U2, typename
330 enable_if<_PCCP::template
331 _MoveConstructiblePair<_U1, _U2>()
332 && !_PCCP::template
333 _ImplicitlyMoveConvertiblePair<_U1, _U2>(),
334 bool>::type=false>
335 explicit constexpr pair(_U1&& __x, _U2&& __y)
336 : first(std::forward<_U1>(__x)), second(std::forward<_U2>(__y)) { }
337
338
339 template<typename _U1, typename _U2, typename
340 enable_if<_PCCFP<_U1, _U2>::template
341 _MoveConstructiblePair<_U1, _U2>()
342 && _PCCFP<_U1, _U2>::template
343 _ImplicitlyMoveConvertiblePair<_U1, _U2>(),
344 bool>::type=true>
345 constexpr pair(pair<_U1, _U2>&& __p)
346 : first(std::forward<_U1>(__p.first)),
347 second(std::forward<_U2>(__p.second)) { }
348
349 template<typename _U1, typename _U2, typename
350 enable_if<_PCCFP<_U1, _U2>::template
351 _MoveConstructiblePair<_U1, _U2>()
352 && !_PCCFP<_U1, _U2>::template
353 _ImplicitlyMoveConvertiblePair<_U1, _U2>(),
354 bool>::type=false>
355 explicit constexpr pair(pair<_U1, _U2>&& __p)
356 : first(std::forward<_U1>(__p.first)),
357 second(std::forward<_U2>(__p.second)) { }
358
359 template<typename... _Args1, typename... _Args2>
360 pair(piecewise_construct_t, tuple<_Args1...>, tuple<_Args2...>);
361
362 pair&
363 operator=(typename conditional<
364 __and_<is_copy_assignable<_T1>,
365 is_copy_assignable<_T2>>::value,
366 const pair&, const __wrap_nonesuch&>::type __p)
367 {
368 first = __p.first;
369 second = __p.second;
370 return *this;
371 }
372
373 pair&
374 operator=(typename conditional<
375 __not_<__and_<is_copy_assignable<_T1>,
376 is_copy_assignable<_T2>>>::value,
377 const pair&, const __wrap_nonesuch&>::type __p) = delete;
378
379 pair&
380 operator=(typename conditional<
381 __and_<is_move_assignable<_T1>,
382 is_move_assignable<_T2>>::value,
383 pair&&, __wrap_nonesuch&&>::type __p)
384 noexcept(__and_<is_nothrow_move_assignable<_T1>,
385 is_nothrow_move_assignable<_T2>>::value)
386 {
387 first = std::forward<first_type>(__p.first);
388 second = std::forward<second_type>(__p.second);
389 return *this;
390 }
391
392 template<typename _U1, typename _U2>
393 typename enable_if<__and_<is_assignable<_T1&, const _U1&>,
394 is_assignable<_T2&, const _U2&>>::value,
395 pair&>::type
396 operator=(const pair<_U1, _U2>& __p)
397 {
398 first = __p.first;
399 second = __p.second;
400 return *this;
401 }
402
403 template<typename _U1, typename _U2>
404 typename enable_if<__and_<is_assignable<_T1&, _U1&&>,
405 is_assignable<_T2&, _U2&&>>::value,
406 pair&>::type
407 operator=(pair<_U1, _U2>&& __p)
408 {
409 first = std::forward<_U1>(__p.first);
410 second = std::forward<_U2>(__p.second);
411 return *this;
412 }
413
414 void
415 swap(pair& __p)
416 noexcept(__is_nothrow_swappable<_T1>::value
417 && __is_nothrow_swappable<_T2>::value)
418 {
419 using std::swap;
420 swap(first, __p.first);
421 swap(second, __p.second);
422 }
423
424 private:
425 template<typename... _Args1, std::size_t... _Indexes1,
426 typename... _Args2, std::size_t... _Indexes2>
427 pair(tuple<_Args1...>&, tuple<_Args2...>&,
428 _Index_tuple<_Indexes1...>, _Index_tuple<_Indexes2...>);
429#endif
430 };
431
432 /// Two pairs of the same type are equal iff their members are equal.
433 template<typename _T1, typename _T2>
434 inline _GLIBCXX_CONSTEXPR bool
435 operator==(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
436 { return __x.first == __y.first && __x.second == __y.second; }
437
438 /// <http://gcc.gnu.org/onlinedocs/libstdc++/manual/utilities.html>
439 template<typename _T1, typename _T2>
440 inline _GLIBCXX_CONSTEXPR bool
441 operator<(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
442 { return __x.first < __y.first
443 || (!(__y.first < __x.first) && __x.second < __y.second); }
444
445 /// Uses @c operator== to find the result.
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 == __y); }
450
451 /// Uses @c operator< to find the result.
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 __y < __x; }
456
457 /// Uses @c operator< to find the result.
458 template<typename _T1, typename _T2>
459 inline _GLIBCXX_CONSTEXPR bool
460 operator<=(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
461 { return !(__y < __x); }
462
463 /// Uses @c operator< to find the result.
464 template<typename _T1, typename _T2>
465 inline _GLIBCXX_CONSTEXPR bool
466 operator>=(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
467 { return !(__x < __y); }
468
469#if __cplusplus >= 201103L
470 /// See std::pair::swap().
471 // Note: no std::swap overloads in C++03 mode, this has performance
472 // implications, see, eg, libstdc++/38466.
473 template<typename _T1, typename _T2>
474 inline void
475 swap(pair<_T1, _T2>& __x, pair<_T1, _T2>& __y)
476 noexcept(noexcept(__x.swap(__y)))
477 { __x.swap(__y); }
478#endif
479
480 /**
481 * @brief A convenience wrapper for creating a pair from two objects.
482 * @param __x The first object.
483 * @param __y The second object.
484 * @return A newly-constructed pair<> object of the appropriate type.
485 *
486 * The standard requires that the objects be passed by reference-to-const,
487 * but LWG issue #181 says they should be passed by const value. We follow
488 * the LWG by default.
489 */
490 // _GLIBCXX_RESOLVE_LIB_DEFECTS
491 // 181. make_pair() unintended behavior
492#if __cplusplus >= 201103L
493 // NB: DR 706.
494 template<typename _T1, typename _T2>
495 constexpr pair<typename __decay_and_strip<_T1>::__type,
496 typename __decay_and_strip<_T2>::__type>
497 make_pair(_T1&& __x, _T2&& __y)
498 {
499 typedef typename __decay_and_strip<_T1>::__type __ds_type1;
500 typedef typename __decay_and_strip<_T2>::__type __ds_type2;
501 typedef pair<__ds_type1, __ds_type2> __pair_type;
502 return __pair_type(std::forward<_T1>(__x), std::forward<_T2>(__y));
503 }
504#else
505 template<typename _T1, typename _T2>
506 inline pair<_T1, _T2>
507 make_pair(_T1 __x, _T2 __y)
508 { return pair<_T1, _T2>(__x, __y); }
509#endif
510
511 /// @}
512
513_GLIBCXX_END_NAMESPACE_VERSION
514} // namespace std
515
516#endif /* _STL_PAIR_H */
517