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
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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
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52 /** @file bits/stl_pair.h
53 * This is an internal header file, included by other library headers.
54 * Do not attempt to use it directly. @headername{utility}
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 namespace std _GLIBCXX_VISIBILITY(default)
68 _GLIBCXX_BEGIN_NAMESPACE_VERSION
70 #ifdef __GXX_EXPERIMENTAL_CXX0X__
71 /// piecewise_construct_t
72 struct piecewise_construct_t { };
74 /// piecewise_construct
75 constexpr piecewise_construct_t piecewise_construct = piecewise_construct_t();
77 // Forward declarations.
85 /// Struct holding two objects of arbitrary type.
86 template<class _T1, class _T2>
89 typedef _T1 first_type; /// @c first_type is the first bound type
90 typedef _T2 second_type; /// @c second_type is the second bound type
92 _T1 first; /// @c first is a copy of the first object
93 _T2 second; /// @c second is a copy of the second object
95 // _GLIBCXX_RESOLVE_LIB_DEFECTS
96 // 265. std::pair::pair() effects overly restrictive
97 /** The default constructor creates @c first and @c second using their
98 * respective default constructors. */
99 _GLIBCXX_CONSTEXPR pair()
100 : first(), second() { }
102 /** Two objects may be passed to a @c pair constructor to be copied. */
103 _GLIBCXX_CONSTEXPR pair(const _T1& __a, const _T2& __b)
104 : first(__a), second(__b) { }
106 /** There is also a templated copy ctor for the @c pair class itself. */
107 template<class _U1, class _U2>
108 _GLIBCXX_CONSTEXPR pair(const pair<_U1, _U2>& __p)
109 : first(__p.first), second(__p.second) { }
111 #ifdef __GXX_EXPERIMENTAL_CXX0X__
112 constexpr pair(const pair&) = default;
115 // pair(pair&&) = default;
118 template<class _U1, class = typename
119 std::enable_if<std::is_convertible<_U1, _T1>::value>::type>
120 pair(_U1&& __x, const _T2& __y)
121 : first(std::forward<_U1>(__x)), second(__y) { }
123 template<class _U2, class = typename
124 std::enable_if<std::is_convertible<_U2, _T2>::value>::type>
125 pair(const _T1& __x, _U2&& __y)
126 : first(__x), second(std::forward<_U2>(__y)) { }
128 template<class _U1, class _U2, class = typename
129 std::enable_if<std::is_convertible<_U1, _T1>::value
130 && std::is_convertible<_U2, _T2>::value>::type>
131 pair(_U1&& __x, _U2&& __y)
132 : first(std::forward<_U1>(__x)), second(std::forward<_U2>(__y)) { }
134 template<class _U1, class _U2>
135 pair(pair<_U1, _U2>&& __p)
136 : first(std::forward<_U1>(__p.first)),
137 second(std::forward<_U2>(__p.second)) { }
139 template<class... _Args1, class... _Args2>
140 pair(piecewise_construct_t,
141 tuple<_Args1...> __first, tuple<_Args2...> __second)
142 : first(__cons<first_type>(std::move(__first))),
143 second(__cons<second_type>(std::move(__second))) { }
146 operator=(const pair& __p)
154 operator=(pair&& __p)
156 first = std::move(__p.first);
157 second = std::move(__p.second);
161 template<class _U1, class _U2>
163 operator=(const pair<_U1, _U2>& __p)
170 template<class _U1, class _U2>
172 operator=(pair<_U1, _U2>&& __p)
174 first = std::move(__p.first);
175 second = std::move(__p.second);
183 swap(first, __p.first);
184 swap(second, __p.second);
188 template<typename _Tp, typename... _Args>
190 __cons(tuple<_Args...>&&);
192 template<typename _Tp, typename... _Args, int... _Indexes>
194 __do_cons(tuple<_Args...>&&, const _Index_tuple<_Indexes...>&);
198 /// Two pairs of the same type are equal iff their members are equal.
199 template<class _T1, class _T2>
200 inline _GLIBCXX_CONSTEXPR bool
201 operator==(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
202 { return __x.first == __y.first && __x.second == __y.second; }
204 /// <http://gcc.gnu.org/onlinedocs/libstdc++/manual/utilities.html>
205 template<class _T1, class _T2>
206 inline _GLIBCXX_CONSTEXPR bool
207 operator<(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
208 { return __x.first < __y.first
209 || (!(__y.first < __x.first) && __x.second < __y.second); }
211 /// Uses @c operator== to find the result.
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 == __y); }
217 /// Uses @c operator< to find the result.
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 __y < __x; }
223 /// Uses @c operator< to find the result.
224 template<class _T1, class _T2>
225 inline _GLIBCXX_CONSTEXPR bool
226 operator<=(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
227 { return !(__y < __x); }
229 /// Uses @c operator< to find the result.
230 template<class _T1, class _T2>
231 inline _GLIBCXX_CONSTEXPR bool
232 operator>=(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
233 { return !(__x < __y); }
235 #ifdef __GXX_EXPERIMENTAL_CXX0X__
236 /// See std::pair::swap().
237 // Note: no std::swap overloads in C++03 mode, this has performance
238 // implications, see, eg, libstdc++/38466.
239 template<class _T1, class _T2>
241 swap(pair<_T1, _T2>& __x, pair<_T1, _T2>& __y)
246 * @brief A convenience wrapper for creating a pair from two objects.
247 * @param x The first object.
248 * @param y The second object.
249 * @return A newly-constructed pair<> object of the appropriate type.
251 * The standard requires that the objects be passed by reference-to-const,
252 * but LWG issue #181 says they should be passed by const value. We follow
253 * the LWG by default.
255 // _GLIBCXX_RESOLVE_LIB_DEFECTS
256 // 181. make_pair() unintended behavior
257 #ifdef __GXX_EXPERIMENTAL_CXX0X__
259 template<class _T1, class _T2>
260 inline pair<typename __decay_and_strip<_T1>::__type,
261 typename __decay_and_strip<_T2>::__type>
262 make_pair(_T1&& __x, _T2&& __y)
264 typedef typename __decay_and_strip<_T1>::__type __ds_type1;
265 typedef typename __decay_and_strip<_T2>::__type __ds_type2;
266 typedef pair<__ds_type1, __ds_type2> __pair_type;
267 return __pair_type(std::forward<_T1>(__x), std::forward<_T2>(__y));
270 template<class _T1, class _T2>
271 inline pair<_T1, _T2>
272 make_pair(_T1 __x, _T2 __y)
273 { return pair<_T1, _T2>(__x, __y); }
276 _GLIBCXX_END_NAMESPACE_VERSION
279 #endif /* _STL_PAIR_H */