1 // Pair implementation -*- C++ -*-
3 // Copyright (C) 2001, 2002, 2003, 2004, 2005, 2006, 2007
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 2, 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 // You should have received a copy of the GNU General Public License along
18 // with this library; see the file COPYING. If not, write to the Free
19 // Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
22 // As a special exception, you may use this file as part of a free software
23 // library without restriction. Specifically, if other files instantiate
24 // templates or use macros or inline functions from this file, or you compile
25 // this file and link it with other files to produce an executable, this
26 // file does not by itself cause the resulting executable to be covered by
27 // the GNU General Public License. This exception does not however
28 // invalidate any other reasons why the executable file might be covered by
29 // the GNU General Public License.
34 * Hewlett-Packard Company
36 * Permission to use, copy, modify, distribute and sell this software
37 * and its documentation for any purpose is hereby granted without fee,
38 * provided that the above copyright notice appear in all copies and
39 * that both that copyright notice and this permission notice appear
40 * in supporting documentation. Hewlett-Packard Company makes no
41 * representations about the suitability of this software for any
42 * purpose. It is provided "as is" without express or implied warranty.
45 * Copyright (c) 1996,1997
46 * Silicon Graphics Computer Systems, Inc.
48 * Permission to use, copy, modify, distribute and sell this software
49 * and its documentation for any purpose is hereby granted without fee,
50 * provided that the above copyright notice appear in all copies and
51 * that both that copyright notice and this permission notice appear
52 * in supporting documentation. Silicon Graphics makes no
53 * representations about the suitability of this software for any
54 * purpose. It is provided "as is" without express or implied warranty.
58 * This is an internal header file, included by other library headers.
59 * You should not attempt to use it directly.
65 #include <bits/stl_move.h> // for std::move / std::forward, std::decay, and
68 _GLIBCXX_BEGIN_NAMESPACE(std
)
70 /// pair holds two objects of arbitrary type.
71 template<class _T1
, class _T2
>
74 typedef _T1 first_type
; ///< @c first_type is the first bound type
75 typedef _T2 second_type
; ///< @c second_type is the second bound type
77 _T1 first
; ///< @c first is a copy of the first object
78 _T2 second
; ///< @c second is a copy of the second object
80 // _GLIBCXX_RESOLVE_LIB_DEFECTS
81 // 265. std::pair::pair() effects overly restrictive
82 /** The default constructor creates @c first and @c second using their
83 * respective default constructors. */
85 : first(), second() { }
87 /** Two objects may be passed to a @c pair constructor to be copied. */
88 pair(const _T1
& __a
, const _T2
& __b
)
89 : first(__a
), second(__b
) { }
91 #ifdef __GXX_EXPERIMENTAL_CXX0X__
92 template<class _U1
, class _U2
>
93 pair(_U1
&& __x
, _U2
&& __y
)
94 : first(std::forward
<_U1
>(__x
)),
95 second(std::forward
<_U2
>(__y
)) { }
98 : first(std::move(__p
.first
)),
99 second(std::move(__p
.second
)) { }
102 /** There is also a templated copy ctor for the @c pair class itself. */
103 template<class _U1
, class _U2
>
104 pair(const pair
<_U1
, _U2
>& __p
)
106 second(__p
.second
) { }
108 #ifdef __GXX_EXPERIMENTAL_CXX0X__
109 template<class _U1
, class _U2
>
110 pair(pair
<_U1
, _U2
>&& __p
)
111 : first(std::move(__p
.first
)),
112 second(std::move(__p
.second
)) { }
114 // http://gcc.gnu.org/ml/libstdc++/2007-08/msg00052.html
115 template<class _U1
, class _Arg0
, class... _Args
>
116 pair(_U1
&& __x
, _Arg0
&& __arg0
, _Args
&&... __args
)
117 : first(std::forward
<_U1
>(__x
)),
118 second(std::forward
<_Arg0
>(__arg0
),
119 std::forward
<_Args
>(__args
)...) { }
122 operator=(pair
&& __p
)
124 first
= std::move(__p
.first
);
125 second
= std::move(__p
.second
);
129 template<class _U1
, class _U2
>
131 operator=(pair
<_U1
, _U2
>&& __p
)
133 first
= std::move(__p
.first
);
134 second
= std::move(__p
.second
);
142 swap(first
, __p
.first
);
143 swap(second
, __p
.second
);
148 /// Two pairs of the same type are equal iff their members are equal.
149 template<class _T1
, class _T2
>
151 operator==(const pair
<_T1
, _T2
>& __x
, const pair
<_T1
, _T2
>& __y
)
152 { return __x
.first
== __y
.first
&& __x
.second
== __y
.second
; }
154 /// <http://gcc.gnu.org/onlinedocs/libstdc++/20_util/howto.html#pairlt>
155 template<class _T1
, class _T2
>
157 operator<(const pair
<_T1
, _T2
>& __x
, const pair
<_T1
, _T2
>& __y
)
158 { return __x
.first
< __y
.first
159 || (!(__y
.first
< __x
.first
) && __x
.second
< __y
.second
); }
161 /// Uses @c operator== to find the result.
162 template<class _T1
, class _T2
>
164 operator!=(const pair
<_T1
, _T2
>& __x
, const pair
<_T1
, _T2
>& __y
)
165 { return !(__x
== __y
); }
167 /// Uses @c operator< to find the result.
168 template<class _T1
, class _T2
>
170 operator>(const pair
<_T1
, _T2
>& __x
, const pair
<_T1
, _T2
>& __y
)
171 { return __y
< __x
; }
173 /// Uses @c operator< to find the result.
174 template<class _T1
, class _T2
>
176 operator<=(const pair
<_T1
, _T2
>& __x
, const pair
<_T1
, _T2
>& __y
)
177 { return !(__y
< __x
); }
179 /// Uses @c operator< to find the result.
180 template<class _T1
, class _T2
>
182 operator>=(const pair
<_T1
, _T2
>& __x
, const pair
<_T1
, _T2
>& __y
)
183 { return !(__x
< __y
); }
185 #ifdef __GXX_EXPERIMENTAL_CXX0X__
186 /// See std::pair::swap().
187 template<class _T1
, class _T2
>
189 swap(pair
<_T1
, _T2
>& __x
, pair
<_T1
, _T2
>& __y
)
192 template<class _T1
, class _T2
>
194 swap(pair
<_T1
, _T2
>&& __x
, pair
<_T1
, _T2
>& __y
)
197 template<class _T1
, class _T2
>
199 swap(pair
<_T1
, _T2
>& __x
, pair
<_T1
, _T2
>&& __y
)
204 * @brief A convenience wrapper for creating a pair from two objects.
205 * @param x The first object.
206 * @param y The second object.
207 * @return A newly-constructed pair<> object of the appropriate type.
209 * The standard requires that the objects be passed by reference-to-const,
210 * but LWG issue #181 says they should be passed by const value. We follow
211 * the LWG by default.
213 // _GLIBCXX_RESOLVE_LIB_DEFECTS
214 // 181. make_pair() unintended behavior
215 #ifndef __GXX_EXPERIMENTAL_CXX0X__
216 template<class _T1
, class _T2
>
217 inline pair
<_T1
, _T2
>
218 make_pair(_T1 __x
, _T2 __y
)
219 { return pair
<_T1
, _T2
>(__x
, __y
); }
221 template<typename _Tp
>
222 class reference_wrapper
;
224 // Helper which adds a reference to a type when given a reference_wrapper
225 template<typename _Tp
>
226 struct __strip_reference_wrapper
231 template<typename _Tp
>
232 struct __strip_reference_wrapper
<reference_wrapper
<_Tp
> >
237 template<typename _Tp
>
238 struct __strip_reference_wrapper
<const reference_wrapper
<_Tp
> >
243 template<typename _Tp
>
244 struct __decay_and_strip
246 typedef typename __strip_reference_wrapper
<
247 typename decay
<_Tp
>::type
>::__type __type
;
251 template<class _T1
, class _T2
>
252 inline pair
<typename __decay_and_strip
<_T1
>::__type
,
253 typename __decay_and_strip
<_T2
>::__type
>
254 make_pair(_T1
&& __x
, _T2
&& __y
)
256 return pair
<typename __decay_and_strip
<_T1
>::__type
,
257 typename __decay_and_strip
<_T2
>::__type
>
258 (std::forward
<_T1
>(__x
), std::forward
<_T2
>(__y
));
262 _GLIBCXX_END_NAMESPACE
264 #endif /* _STL_PAIR_H */