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.
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;
121 // XXX Defaulted?!? Breaks std::map!!!
123 noexcept(__and_<is_nothrow_move_constructible<_T1>,
124 is_nothrow_move_constructible<_T2>>::value)
125 : first(std::forward<first_type>(__p.first)),
126 second(std::forward<second_type>(__p.second)) { }
129 template<class _U1, class = typename
130 enable_if<is_convertible<_U1, _T1>::value>::type>
131 pair(_U1&& __x, const _T2& __y)
132 : first(std::forward<_U1>(__x)), second(__y) { }
134 template<class _U2, class = typename
135 enable_if<is_convertible<_U2, _T2>::value>::type>
136 pair(const _T1& __x, _U2&& __y)
137 : first(__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 pair(_U1&& __x, _U2&& __y)
143 : first(std::forward<_U1>(__x)), second(std::forward<_U2>(__y)) { }
145 template<class _U1, class _U2, class = typename
146 enable_if<__and_<is_convertible<_U1, _T1>,
147 is_convertible<_U2, _T2>>::value>::type>
148 pair(pair<_U1, _U2>&& __p)
149 : first(std::forward<_U1>(__p.first)),
150 second(std::forward<_U2>(__p.second)) { }
152 template<class... _Args1, class... _Args2>
153 pair(piecewise_construct_t,
154 tuple<_Args1...> __first, tuple<_Args2...> __second)
155 : first(__cons<first_type>(std::move(__first))),
156 second(__cons<second_type>(std::move(__second))) { }
159 operator=(const pair& __p)
167 operator=(pair&& __p)
168 noexcept(__and_<is_nothrow_move_assignable<_T1>,
169 is_nothrow_move_assignable<_T2>>::value)
171 first = std::forward<first_type>(__p.first);
172 second = std::forward<second_type>(__p.second);
176 template<class _U1, class _U2>
178 operator=(const pair<_U1, _U2>& __p)
185 template<class _U1, class _U2>
187 operator=(pair<_U1, _U2>&& __p)
189 first = std::forward<_U1>(__p.first);
190 second = std::forward<_U2>(__p.second);
196 noexcept(noexcept(swap(first, __p.first))
197 && noexcept(swap(second, __p.second)))
200 swap(first, __p.first);
201 swap(second, __p.second);
205 template<typename _Tp, typename... _Args>
207 __cons(tuple<_Args...>&&);
209 template<typename _Tp, typename... _Args, int... _Indexes>
211 __do_cons(tuple<_Args...>&&, const _Index_tuple<_Indexes...>&);
215 /// Two pairs of the same type are equal iff their members are equal.
216 template<class _T1, class _T2>
217 inline _GLIBCXX_CONSTEXPR bool
218 operator==(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
219 { return __x.first == __y.first && __x.second == __y.second; }
221 /// <http://gcc.gnu.org/onlinedocs/libstdc++/manual/utilities.html>
222 template<class _T1, class _T2>
223 inline _GLIBCXX_CONSTEXPR bool
224 operator<(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
225 { return __x.first < __y.first
226 || (!(__y.first < __x.first) && __x.second < __y.second); }
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 !(__x == __y); }
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 __y < __x; }
240 /// Uses @c operator< to find the result.
241 template<class _T1, class _T2>
242 inline _GLIBCXX_CONSTEXPR bool
243 operator<=(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
244 { return !(__y < __x); }
246 /// Uses @c operator< to find the result.
247 template<class _T1, class _T2>
248 inline _GLIBCXX_CONSTEXPR bool
249 operator>=(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
250 { return !(__x < __y); }
252 #ifdef __GXX_EXPERIMENTAL_CXX0X__
253 /// See std::pair::swap().
254 // Note: no std::swap overloads in C++03 mode, this has performance
255 // implications, see, eg, libstdc++/38466.
256 template<class _T1, class _T2>
258 swap(pair<_T1, _T2>& __x, pair<_T1, _T2>& __y)
259 noexcept(noexcept(__x.swap(__y)))
264 * @brief A convenience wrapper for creating a pair from two objects.
265 * @param x The first object.
266 * @param y The second object.
267 * @return A newly-constructed pair<> object of the appropriate type.
269 * The standard requires that the objects be passed by reference-to-const,
270 * but LWG issue #181 says they should be passed by const value. We follow
271 * the LWG by default.
273 // _GLIBCXX_RESOLVE_LIB_DEFECTS
274 // 181. make_pair() unintended behavior
275 #ifdef __GXX_EXPERIMENTAL_CXX0X__
277 template<class _T1, class _T2>
278 inline pair<typename __decay_and_strip<_T1>::__type,
279 typename __decay_and_strip<_T2>::__type>
280 make_pair(_T1&& __x, _T2&& __y)
282 typedef typename __decay_and_strip<_T1>::__type __ds_type1;
283 typedef typename __decay_and_strip<_T2>::__type __ds_type2;
284 typedef pair<__ds_type1, __ds_type2> __pair_type;
285 return __pair_type(std::forward<_T1>(__x), std::forward<_T2>(__y));
288 template<class _T1, class _T2>
289 inline pair<_T1, _T2>
290 make_pair(_T1 __x, _T2 __y)
291 { return pair<_T1, _T2>(__x, __y); }
294 _GLIBCXX_END_NAMESPACE_VERSION
297 #endif /* _STL_PAIR_H */