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, and std::swap
62 #ifdef __GXX_EXPERIMENTAL_CXX0X__
63 #include <type_traits> // for std::__decay_and_strip too
66 _GLIBCXX_BEGIN_NAMESPACE(std)
68 #ifdef __GXX_EXPERIMENTAL_CXX0X__
69 struct piecewise_construct_t { };
71 static const piecewise_construct_t piecewise_construct
72 = piecewise_construct_t();
74 // forward declarations
82 /// pair holds two objects of arbitrary type.
83 template<class _T1, class _T2>
86 typedef _T1 first_type; ///< @c first_type is the first bound type
87 typedef _T2 second_type; ///< @c second_type is the second bound type
89 _T1 first; ///< @c first is a copy of the first object
90 _T2 second; ///< @c second is a copy of the second object
92 // _GLIBCXX_RESOLVE_LIB_DEFECTS
93 // 265. std::pair::pair() effects overly restrictive
94 /** The default constructor creates @c first and @c second using their
95 * respective default constructors. */
97 : first(), second() { }
99 /** Two objects may be passed to a @c pair constructor to be copied. */
100 pair(const _T1& __a, const _T2& __b)
101 : first(__a), second(__b) { }
103 #ifdef __GXX_EXPERIMENTAL_CXX0X__
104 pair(const pair&) = default;
107 template<class _U1, class = typename
108 std::enable_if<std::is_convertible<_U1, _T1>::value>::type>
109 pair(_U1&& __x, const _T2& __y)
110 : first(std::forward<_U1>(__x)),
113 template<class _U2, class = typename
114 std::enable_if<std::is_convertible<_U2, _T2>::value>::type>
115 pair(const _T1& __x, _U2&& __y)
117 second(std::forward<_U2>(__y)) { }
119 template<class _U1, class _U2, class = typename
120 std::enable_if<std::is_convertible<_U1, _T1>::value
121 && std::is_convertible<_U2, _T2>::value>::type>
122 pair(_U1&& __x, _U2&& __y)
123 : first(std::forward<_U1>(__x)),
124 second(std::forward<_U2>(__y)) { }
126 template<class... _Args1, class... _Args2>
127 pair(piecewise_construct_t,
128 tuple<_Args1...> __first_args,
129 tuple<_Args2...> __second_args)
130 : first(__cons<first_type>(std::move(__first_args))),
131 second(__cons<second_type>(std::move(__second_args))) { }
134 /** There is also a templated copy ctor for the @c pair class itself. */
135 template<class _U1, class _U2>
136 pair(const pair<_U1, _U2>& __p)
138 second(__p.second) { }
140 #ifdef __GXX_EXPERIMENTAL_CXX0X__
141 template<class _U1, class _U2>
142 pair(pair<_U1, _U2>&& __p)
143 : first(std::forward<_U1>(__p.first)),
144 second(std::forward<_U2>(__p.second)) { }
147 operator=(pair&& __p)
149 first = std::move(__p.first);
150 second = std::move(__p.second);
154 template<class _U1, class _U2>
156 operator=(const pair<_U1, _U2>& __p)
163 template<class _U1, class _U2>
165 operator=(pair<_U1, _U2>&& __p)
167 first = std::move(__p.first);
168 second = std::move(__p.second);
176 swap(first, __p.first);
177 swap(second, __p.second);
181 template<typename _Tp, typename... _Args>
183 __cons(tuple<_Args...>&&);
185 template<typename _Tp, typename... _Args, int... _Indexes>
187 __do_cons(tuple<_Args...>&&, const _Index_tuple<_Indexes...>&);
191 /// Two pairs of the same type are equal iff their members are equal.
192 template<class _T1, class _T2>
194 operator==(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
195 { return __x.first == __y.first && __x.second == __y.second; }
197 /// <http://gcc.gnu.org/onlinedocs/libstdc++/manual/utilities.html>
198 template<class _T1, class _T2>
200 operator<(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
201 { return __x.first < __y.first
202 || (!(__y.first < __x.first) && __x.second < __y.second); }
204 /// Uses @c operator== to find the result.
205 template<class _T1, class _T2>
207 operator!=(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
208 { return !(__x == __y); }
210 /// Uses @c operator< to find the result.
211 template<class _T1, class _T2>
213 operator>(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
214 { return __y < __x; }
216 /// Uses @c operator< to find the result.
217 template<class _T1, class _T2>
219 operator<=(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
220 { return !(__y < __x); }
222 /// Uses @c operator< to find the result.
223 template<class _T1, class _T2>
225 operator>=(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
226 { return !(__x < __y); }
228 #ifdef __GXX_EXPERIMENTAL_CXX0X__
229 /// See std::pair::swap().
230 // Note: no std::swap overloads in C++03 mode, this has performance
231 // implications, see, eg, libstdc++/38466.
232 template<class _T1, class _T2>
234 swap(pair<_T1, _T2>& __x, pair<_T1, _T2>& __y)
239 * @brief A convenience wrapper for creating a pair from two objects.
240 * @param x The first object.
241 * @param y The second object.
242 * @return A newly-constructed pair<> object of the appropriate type.
244 * The standard requires that the objects be passed by reference-to-const,
245 * but LWG issue #181 says they should be passed by const value. We follow
246 * the LWG by default.
248 // _GLIBCXX_RESOLVE_LIB_DEFECTS
249 // 181. make_pair() unintended behavior
250 #ifndef __GXX_EXPERIMENTAL_CXX0X__
251 template<class _T1, class _T2>
252 inline pair<_T1, _T2>
253 make_pair(_T1 __x, _T2 __y)
254 { return pair<_T1, _T2>(__x, __y); }
257 template<class _T1, class _T2>
258 inline pair<typename __decay_and_strip<_T1>::__type,
259 typename __decay_and_strip<_T2>::__type>
260 make_pair(_T1&& __x, _T2&& __y)
262 return pair<typename __decay_and_strip<_T1>::__type,
263 typename __decay_and_strip<_T2>::__type>
264 (std::forward<_T1>(__x), std::forward<_T2>(__y));
268 _GLIBCXX_END_NAMESPACE
270 #endif /* _STL_PAIR_H */