1 // Pair implementation -*- C++ -*-
3 // Copyright (C) 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009,
5 // Free Software Foundation, Inc.
7 // This file is part of the GNU ISO C++ Library. This library is free
8 // software; you can redistribute it and/or modify it under the
9 // terms of the GNU General Public License as published by the
10 // Free Software Foundation; either version 3, or (at your option)
13 // This library is distributed in the hope that it will be useful,
14 // but WITHOUT ANY WARRANTY; without even the implied warranty of
15 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 // GNU General Public License for more details.
18 // Under Section 7 of GPL version 3, you are granted additional
19 // permissions described in the GCC Runtime Library Exception, version
20 // 3.1, as published by the Free Software Foundation.
22 // You should have received a copy of the GNU General Public License and
23 // a copy of the GCC Runtime Library Exception along with this program;
24 // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
25 // <http://www.gnu.org/licenses/>.
30 * Hewlett-Packard Company
32 * Permission to use, copy, modify, distribute and sell this software
33 * and its documentation for any purpose is hereby granted without fee,
34 * provided that the above copyright notice appear in all copies and
35 * that both that copyright notice and this permission notice appear
36 * in supporting documentation. Hewlett-Packard Company makes no
37 * representations about the suitability of this software for any
38 * purpose. It is provided "as is" without express or implied warranty.
41 * Copyright (c) 1996,1997
42 * Silicon Graphics Computer Systems, Inc.
44 * Permission to use, copy, modify, distribute and sell this software
45 * and its documentation for any purpose is hereby granted without fee,
46 * provided that the above copyright notice appear in all copies and
47 * that both that copyright notice and this permission notice appear
48 * in supporting documentation. Silicon Graphics makes no
49 * representations about the suitability of this software for any
50 * purpose. It is provided "as is" without express or implied warranty.
53 /** @file bits/stl_pair.h
54 * This is an internal header file, included by other library headers.
55 * Do not attempt to use it directly. @headername{utility}
61 #include <bits/move.h> // for std::move / std::forward, and std::swap
63 #ifdef __GXX_EXPERIMENTAL_CXX0X__
64 #include <type_traits> // for std::__decay_and_strip too
67 namespace std _GLIBCXX_VISIBILITY(default)
69 _GLIBCXX_BEGIN_NAMESPACE_VERSION
71 #ifdef __GXX_EXPERIMENTAL_CXX0X__
72 /// piecewise_construct_t
73 struct piecewise_construct_t { };
75 /// piecewise_construct
76 constexpr piecewise_construct_t piecewise_construct = piecewise_construct_t();
78 // Forward declarations.
82 template<std::size_t...>
86 /// Struct holding two objects of arbitrary type.
87 template<class _T1, class _T2>
90 typedef _T1 first_type; /// @c first_type is the first bound type
91 typedef _T2 second_type; /// @c second_type is the second bound type
93 _T1 first; /// @c first is a copy of the first object
94 _T2 second; /// @c second is a copy of the second object
96 // _GLIBCXX_RESOLVE_LIB_DEFECTS
97 // 265. std::pair::pair() effects overly restrictive
98 /** The default constructor creates @c first and @c second using their
99 * respective default constructors. */
100 _GLIBCXX_CONSTEXPR pair()
101 : first(), second() { }
103 /** Two objects may be passed to a @c pair constructor to be copied. */
104 _GLIBCXX_CONSTEXPR pair(const _T1& __a, const _T2& __b)
105 : first(__a), second(__b) { }
107 /** There is also a templated copy ctor for the @c pair class itself. */
108 #ifndef __GXX_EXPERIMENTAL_CXX0X__
109 template<class _U1, class _U2>
110 pair(const pair<_U1, _U2>& __p)
111 : first(__p.first), second(__p.second) { }
113 template<class _U1, class _U2, class = typename
114 enable_if<__and_<is_convertible<const _U1&, _T1>,
115 is_convertible<const _U2&, _T2>>::value>::type>
116 constexpr pair(const pair<_U1, _U2>& __p)
117 : first(__p.first), second(__p.second) { }
119 constexpr pair(const pair&) = default;
120 constexpr pair(pair&&) = default;
123 template<class _U1, class = typename
124 enable_if<is_convertible<_U1, _T1>::value>::type>
125 constexpr pair(_U1&& __x, const _T2& __y)
126 : first(std::forward<_U1>(__x)), second(__y) { }
128 template<class _U2, class = typename
129 enable_if<is_convertible<_U2, _T2>::value>::type>
130 constexpr pair(const _T1& __x, _U2&& __y)
131 : first(__x), second(std::forward<_U2>(__y)) { }
133 template<class _U1, class _U2, class = typename
134 enable_if<__and_<is_convertible<_U1, _T1>,
135 is_convertible<_U2, _T2>>::value>::type>
136 constexpr pair(_U1&& __x, _U2&& __y)
137 : first(std::forward<_U1>(__x)), second(std::forward<_U2>(__y)) { }
139 template<class _U1, class _U2, class = typename
140 enable_if<__and_<is_convertible<_U1, _T1>,
141 is_convertible<_U2, _T2>>::value>::type>
142 constexpr pair(pair<_U1, _U2>&& __p)
143 : first(std::forward<_U1>(__p.first)),
144 second(std::forward<_U2>(__p.second)) { }
146 template<typename... _Args1, typename... _Args2>
147 pair(piecewise_construct_t, tuple<_Args1...>, tuple<_Args2...>);
150 operator=(const pair& __p)
158 operator=(pair&& __p)
159 noexcept(__and_<is_nothrow_move_assignable<_T1>,
160 is_nothrow_move_assignable<_T2>>::value)
162 first = std::forward<first_type>(__p.first);
163 second = std::forward<second_type>(__p.second);
167 template<class _U1, class _U2>
169 operator=(const pair<_U1, _U2>& __p)
176 template<class _U1, class _U2>
178 operator=(pair<_U1, _U2>&& __p)
180 first = std::forward<_U1>(__p.first);
181 second = std::forward<_U2>(__p.second);
187 noexcept(noexcept(swap(first, __p.first))
188 && noexcept(swap(second, __p.second)))
191 swap(first, __p.first);
192 swap(second, __p.second);
196 template<typename... _Args1, std::size_t... _Indexes1,
197 typename... _Args2, std::size_t... _Indexes2>
198 pair(tuple<_Args1...>&, tuple<_Args2...>&,
199 _Index_tuple<_Indexes1...>, _Index_tuple<_Indexes2...>);
203 /// Two pairs of the same type are equal iff their members are equal.
204 template<class _T1, class _T2>
205 inline _GLIBCXX_CONSTEXPR bool
206 operator==(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
207 { return __x.first == __y.first && __x.second == __y.second; }
209 /// <http://gcc.gnu.org/onlinedocs/libstdc++/manual/utilities.html>
210 template<class _T1, class _T2>
211 inline _GLIBCXX_CONSTEXPR bool
212 operator<(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
213 { return __x.first < __y.first
214 || (!(__y.first < __x.first) && __x.second < __y.second); }
216 /// Uses @c operator== to find the result.
217 template<class _T1, class _T2>
218 inline _GLIBCXX_CONSTEXPR bool
219 operator!=(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
220 { return !(__x == __y); }
222 /// Uses @c operator< to find the result.
223 template<class _T1, class _T2>
224 inline _GLIBCXX_CONSTEXPR bool
225 operator>(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
226 { return __y < __x; }
228 /// Uses @c operator< to find the result.
229 template<class _T1, class _T2>
230 inline _GLIBCXX_CONSTEXPR bool
231 operator<=(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
232 { return !(__y < __x); }
234 /// Uses @c operator< to find the result.
235 template<class _T1, class _T2>
236 inline _GLIBCXX_CONSTEXPR bool
237 operator>=(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
238 { return !(__x < __y); }
240 #ifdef __GXX_EXPERIMENTAL_CXX0X__
241 /// See std::pair::swap().
242 // Note: no std::swap overloads in C++03 mode, this has performance
243 // implications, see, eg, libstdc++/38466.
244 template<class _T1, class _T2>
246 swap(pair<_T1, _T2>& __x, pair<_T1, _T2>& __y)
247 noexcept(noexcept(__x.swap(__y)))
252 * @brief A convenience wrapper for creating a pair from two objects.
253 * @param __x The first object.
254 * @param __y The second object.
255 * @return A newly-constructed pair<> object of the appropriate type.
257 * The standard requires that the objects be passed by reference-to-const,
258 * but LWG issue #181 says they should be passed by const value. We follow
259 * the LWG by default.
261 // _GLIBCXX_RESOLVE_LIB_DEFECTS
262 // 181. make_pair() unintended behavior
263 #ifdef __GXX_EXPERIMENTAL_CXX0X__
265 template<class _T1, class _T2>
266 constexpr pair<typename __decay_and_strip<_T1>::__type,
267 typename __decay_and_strip<_T2>::__type>
268 make_pair(_T1&& __x, _T2&& __y)
270 typedef typename __decay_and_strip<_T1>::__type __ds_type1;
271 typedef typename __decay_and_strip<_T2>::__type __ds_type2;
272 typedef pair<__ds_type1, __ds_type2> __pair_type;
273 return __pair_type(std::forward<_T1>(__x), std::forward<_T2>(__y));
276 template<class _T1, class _T2>
277 inline pair<_T1, _T2>
278 make_pair(_T1 __x, _T2 __y)
279 { return pair<_T1, _T2>(__x, __y); }
282 _GLIBCXX_END_NAMESPACE_VERSION
285 #endif /* _STL_PAIR_H */