libstdc++

stl_pair.h
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1 // Pair implementation -*- C++ -*-
2
3 // Copyright (C) 2001-2013 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
65 namespace 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 { };
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 #endif
88
89 /**
90 * @brief Struct holding two objects of arbitrary type.
91 *
92 * @tparam _T1 Type of first object.
93 * @tparam _T2 Type of second object.
94 */
95 template<class _T1, class _T2>
96 struct pair
97 {
98 typedef _T1 first_type; /// @c first_type is the first bound type
99 typedef _T2 second_type; /// @c second_type is the second bound type
100
101 _T1 first; /// @c first is a copy of the first object
102 _T2 second; /// @c second is a copy of the second object
103
104 // _GLIBCXX_RESOLVE_LIB_DEFECTS
105 // 265. std::pair::pair() effects overly restrictive
106 /** The default constructor creates @c first and @c second using their
107 * respective default constructors. */
108 _GLIBCXX_CONSTEXPR pair()
109 : first(), second() { }
110
111 /** Two objects may be passed to a @c pair constructor to be copied. */
112 _GLIBCXX_CONSTEXPR pair(const _T1& __a, const _T2& __b)
113 : first(__a), second(__b) { }
114
115 /** There is also a templated copy ctor for the @c pair class itself. */
116 #if __cplusplus < 201103L
117 template<class _U1, class _U2>
118 pair(const pair<_U1, _U2>& __p)
119 : first(__p.first), second(__p.second) { }
120 #else
121 template<class _U1, class _U2, class = typename
122 enable_if<__and_<is_convertible<const _U1&, _T1>,
123 is_convertible<const _U2&, _T2>>::value>::type>
124 constexpr pair(const pair<_U1, _U2>& __p)
125 : first(__p.first), second(__p.second) { }
126
127 constexpr pair(const pair&) = default;
128 constexpr pair(pair&&) = default;
129
130 // DR 811.
131 template<class _U1, class = typename
132 enable_if<is_convertible<_U1, _T1>::value>::type>
133 constexpr pair(_U1&& __x, const _T2& __y)
134 : first(std::forward<_U1>(__x)), second(__y) { }
135
136 template<class _U2, class = typename
137 enable_if<is_convertible<_U2, _T2>::value>::type>
138 constexpr pair(const _T1& __x, _U2&& __y)
139 : first(__x), second(std::forward<_U2>(__y)) { }
140
141 template<class _U1, class _U2, class = typename
142 enable_if<__and_<is_convertible<_U1, _T1>,
143 is_convertible<_U2, _T2>>::value>::type>
144 constexpr pair(_U1&& __x, _U2&& __y)
145 : first(std::forward<_U1>(__x)), second(std::forward<_U2>(__y)) { }
146
147 template<class _U1, class _U2, class = typename
148 enable_if<__and_<is_convertible<_U1, _T1>,
149 is_convertible<_U2, _T2>>::value>::type>
150 constexpr pair(pair<_U1, _U2>&& __p)
151 : first(std::forward<_U1>(__p.first)),
152 second(std::forward<_U2>(__p.second)) { }
153
154 template<typename... _Args1, typename... _Args2>
155 pair(piecewise_construct_t, tuple<_Args1...>, tuple<_Args2...>);
156
157 pair&
158 operator=(const pair& __p)
159 {
160 first = __p.first;
161 second = __p.second;
162 return *this;
163 }
164
165 pair&
166 operator=(pair&& __p)
167 noexcept(__and_<is_nothrow_move_assignable<_T1>,
168 is_nothrow_move_assignable<_T2>>::value)
169 {
170 first = std::forward<first_type>(__p.first);
171 second = std::forward<second_type>(__p.second);
172 return *this;
173 }
174
175 template<class _U1, class _U2>
176 pair&
177 operator=(const pair<_U1, _U2>& __p)
178 {
179 first = __p.first;
180 second = __p.second;
181 return *this;
182 }
183
184 template<class _U1, class _U2>
185 pair&
186 operator=(pair<_U1, _U2>&& __p)
187 {
188 first = std::forward<_U1>(__p.first);
189 second = std::forward<_U2>(__p.second);
190 return *this;
191 }
192
193 void
194 swap(pair& __p)
195 noexcept(noexcept(swap(first, __p.first))
196 && noexcept(swap(second, __p.second)))
197 {
198 using std::swap;
199 swap(first, __p.first);
200 swap(second, __p.second);
201 }
202
203 private:
204 template<typename... _Args1, std::size_t... _Indexes1,
205 typename... _Args2, std::size_t... _Indexes2>
206 pair(tuple<_Args1...>&, tuple<_Args2...>&,
207 _Index_tuple<_Indexes1...>, _Index_tuple<_Indexes2...>);
208 #endif
209 };
210
211 /// Two pairs of the same type are equal iff their members are equal.
212 template<class _T1, class _T2>
213 inline _GLIBCXX_CONSTEXPR bool
214 operator==(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
215 { return __x.first == __y.first && __x.second == __y.second; }
216
217 /// <http://gcc.gnu.org/onlinedocs/libstdc++/manual/utilities.html>
218 template<class _T1, class _T2>
219 inline _GLIBCXX_CONSTEXPR bool
220 operator<(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
221 { return __x.first < __y.first
222 || (!(__y.first < __x.first) && __x.second < __y.second); }
223
224 /// Uses @c operator== to find the result.
225 template<class _T1, class _T2>
226 inline _GLIBCXX_CONSTEXPR bool
227 operator!=(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
228 { return !(__x == __y); }
229
230 /// Uses @c operator< to find the result.
231 template<class _T1, class _T2>
232 inline _GLIBCXX_CONSTEXPR bool
233 operator>(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
234 { return __y < __x; }
235
236 /// Uses @c operator< to find the result.
237 template<class _T1, class _T2>
238 inline _GLIBCXX_CONSTEXPR bool
239 operator<=(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
240 { return !(__y < __x); }
241
242 /// Uses @c operator< to find the result.
243 template<class _T1, class _T2>
244 inline _GLIBCXX_CONSTEXPR bool
245 operator>=(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
246 { return !(__x < __y); }
247
248 #if __cplusplus >= 201103L
249 /// See std::pair::swap().
250 // Note: no std::swap overloads in C++03 mode, this has performance
251 // implications, see, eg, libstdc++/38466.
252 template<class _T1, class _T2>
253 inline void
254 swap(pair<_T1, _T2>& __x, pair<_T1, _T2>& __y)
255 noexcept(noexcept(__x.swap(__y)))
256 { __x.swap(__y); }
257 #endif
258
259 /**
260 * @brief A convenience wrapper for creating a pair from two objects.
261 * @param __x The first object.
262 * @param __y The second object.
263 * @return A newly-constructed pair<> object of the appropriate type.
264 *
265 * The standard requires that the objects be passed by reference-to-const,
266 * but LWG issue #181 says they should be passed by const value. We follow
267 * the LWG by default.
268 */
269 // _GLIBCXX_RESOLVE_LIB_DEFECTS
270 // 181. make_pair() unintended behavior
271 #if __cplusplus >= 201103L
272 // NB: DR 706.
273 template<class _T1, class _T2>
274 constexpr pair<typename __decay_and_strip<_T1>::__type,
275 typename __decay_and_strip<_T2>::__type>
276 make_pair(_T1&& __x, _T2&& __y)
277 {
278 typedef typename __decay_and_strip<_T1>::__type __ds_type1;
279 typedef typename __decay_and_strip<_T2>::__type __ds_type2;
280 typedef pair<__ds_type1, __ds_type2> __pair_type;
281 return __pair_type(std::forward<_T1>(__x), std::forward<_T2>(__y));
282 }
283 #else
284 template<class _T1, class _T2>
285 inline pair<_T1, _T2>
286 make_pair(_T1 __x, _T2 __y)
287 { return pair<_T1, _T2>(__x, __y); }
288 #endif
289
290 /// @}
291
292 _GLIBCXX_END_NAMESPACE_VERSION
293 } // namespace std
294
295 #endif /* _STL_PAIR_H */