1 // Pair implementation -*- C++ -*-
3 // Copyright (C) 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010
4 // Free Software Foundation, Inc.
6 // This file is part of the GNU ISO C++ Library. This library is free
7 // software; you can redistribute it and/or modify it under the
8 // terms of the GNU General Public License as published by the
9 // Free Software Foundation; either version 3, or (at your option)
12 // This library is distributed in the hope that it will be useful,
13 // but WITHOUT ANY WARRANTY; without even the implied warranty of
14 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 // GNU General Public License for more details.
17 // Under Section 7 of GPL version 3, you are granted additional
18 // permissions described in the GCC Runtime Library Exception, version
19 // 3.1, as published by the Free Software Foundation.
21 // You should have received a copy of the GNU General Public License and
22 // a copy of the GCC Runtime Library Exception along with this program;
23 // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
24 // <http://www.gnu.org/licenses/>.
29 * Hewlett-Packard Company
31 * Permission to use, copy, modify, distribute and sell this software
32 * and its documentation for any purpose is hereby granted without fee,
33 * provided that the above copyright notice appear in all copies and
34 * that both that copyright notice and this permission notice appear
35 * in supporting documentation. Hewlett-Packard Company makes no
36 * representations about the suitability of this software for any
37 * purpose. It is provided "as is" without express or implied warranty.
40 * Copyright (c) 1996,1997
41 * Silicon Graphics Computer Systems, Inc.
43 * Permission to use, copy, modify, distribute and sell this software
44 * and its documentation for any purpose is hereby granted without fee,
45 * provided that the above copyright notice appear in all copies and
46 * that both that copyright notice and this permission notice appear
47 * in supporting documentation. Silicon Graphics makes no
48 * representations about the suitability of this software for any
49 * purpose. It is provided "as is" without express or implied warranty.
53 * This is an internal header file, included by other library headers.
54 * You should not attempt to use it directly.
60 #include <bits/move.h> // for std::move / std::forward, std::decay, and
63 #ifdef __GXX_EXPERIMENTAL_CXX0X__
64 #include <type_traits>
67 _GLIBCXX_BEGIN_NAMESPACE(std)
69 /// pair holds two objects of arbitrary type.
70 template<class _T1, class _T2>
73 typedef _T1 first_type; ///< @c first_type is the first bound type
74 typedef _T2 second_type; ///< @c second_type is the second bound type
76 _T1 first; ///< @c first is a copy of the first object
77 _T2 second; ///< @c second is a copy of the second object
79 // _GLIBCXX_RESOLVE_LIB_DEFECTS
80 // 265. std::pair::pair() effects overly restrictive
81 /** The default constructor creates @c first and @c second using their
82 * respective default constructors. */
84 : first(), second() { }
86 /** Two objects may be passed to a @c pair constructor to be copied. */
87 pair(const _T1& __a, const _T2& __b)
88 : first(__a), second(__b) { }
90 #ifdef __GXX_EXPERIMENTAL_CXX0X__
92 template<class _U1, class = typename
93 std::enable_if<std::is_convertible<_U1, _T1>::value>::type>
94 pair(_U1&& __x, const _T2& __y)
95 : first(std::forward<_U1>(__x)),
98 template<class _U2, class = typename
99 std::enable_if<std::is_convertible<_U2, _T2>::value>::type>
100 pair(const _T1& __x, _U2&& __y)
102 second(std::forward<_U2>(__y)) { }
104 template<class _U1, class _U2, class = typename
105 std::enable_if<std::is_convertible<_U1, _T1>::value
106 && std::is_convertible<_U2, _T2>::value>::type>
107 pair(_U1&& __x, _U2&& __y)
108 : first(std::forward<_U1>(__x)),
109 second(std::forward<_U2>(__y)) { }
112 /** There is also a templated copy ctor for the @c pair class itself. */
113 template<class _U1, class _U2>
114 pair(const pair<_U1, _U2>& __p)
116 second(__p.second) { }
118 #ifdef __GXX_EXPERIMENTAL_CXX0X__
119 template<class _U1, class _U2>
120 pair(pair<_U1, _U2>&& __p)
121 : first(std::forward<_U1>(__p.first)),
122 second(std::forward<_U2>(__p.second)) { }
125 operator=(pair&& __p)
127 first = std::move(__p.first);
128 second = std::move(__p.second);
132 template<class _U1, class _U2>
134 operator=(pair<_U1, _U2>&& __p)
136 first = std::move(__p.first);
137 second = std::move(__p.second);
145 swap(first, __p.first);
146 swap(second, __p.second);
151 /// Two pairs of the same type are equal iff their members are equal.
152 template<class _T1, class _T2>
154 operator==(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
155 { return __x.first == __y.first && __x.second == __y.second; }
157 /// <http://gcc.gnu.org/onlinedocs/libstdc++/manual/utilities.html>
158 template<class _T1, class _T2>
160 operator<(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
161 { return __x.first < __y.first
162 || (!(__y.first < __x.first) && __x.second < __y.second); }
164 /// Uses @c operator== to find the result.
165 template<class _T1, class _T2>
167 operator!=(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
168 { return !(__x == __y); }
170 /// Uses @c operator< to find the result.
171 template<class _T1, class _T2>
173 operator>(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
174 { return __y < __x; }
176 /// Uses @c operator< to find the result.
177 template<class _T1, class _T2>
179 operator<=(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
180 { return !(__y < __x); }
182 /// Uses @c operator< to find the result.
183 template<class _T1, class _T2>
185 operator>=(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
186 { return !(__x < __y); }
188 #ifdef __GXX_EXPERIMENTAL_CXX0X__
189 /// See std::pair::swap().
190 // Note: no std::swap overloads in C++03 mode, this has performance
191 // implications, see, eg, libstdc++/38466.
192 template<class _T1, class _T2>
194 swap(pair<_T1, _T2>& __x, pair<_T1, _T2>& __y)
199 * @brief A convenience wrapper for creating a pair from two objects.
200 * @param x The first object.
201 * @param y The second object.
202 * @return A newly-constructed pair<> object of the appropriate type.
204 * The standard requires that the objects be passed by reference-to-const,
205 * but LWG issue #181 says they should be passed by const value. We follow
206 * the LWG by default.
208 // _GLIBCXX_RESOLVE_LIB_DEFECTS
209 // 181. make_pair() unintended behavior
210 #ifndef __GXX_EXPERIMENTAL_CXX0X__
211 template<class _T1, class _T2>
212 inline pair<_T1, _T2>
213 make_pair(_T1 __x, _T2 __y)
214 { return pair<_T1, _T2>(__x, __y); }
216 template<typename _Tp>
217 class reference_wrapper;
219 // Helper which adds a reference to a type when given a reference_wrapper
220 template<typename _Tp>
221 struct __strip_reference_wrapper
226 template<typename _Tp>
227 struct __strip_reference_wrapper<reference_wrapper<_Tp> >
232 template<typename _Tp>
233 struct __strip_reference_wrapper<const reference_wrapper<_Tp> >
238 template<typename _Tp>
239 struct __decay_and_strip
241 typedef typename __strip_reference_wrapper<
242 typename decay<_Tp>::type>::__type __type;
246 template<class _T1, class _T2>
247 inline pair<typename __decay_and_strip<_T1>::__type,
248 typename __decay_and_strip<_T2>::__type>
249 make_pair(_T1&& __x, _T2&& __y)
251 return pair<typename __decay_and_strip<_T1>::__type,
252 typename __decay_and_strip<_T2>::__type>
253 (std::forward<_T1>(__x), std::forward<_T2>(__y));
257 _GLIBCXX_END_NAMESPACE
259 #endif /* _STL_PAIR_H */