1 // Pair implementation -*- C++ -*-
3 // Copyright (C) 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009
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, std::decay, and
63 _GLIBCXX_BEGIN_NAMESPACE(std
)
65 /// pair holds two objects of arbitrary type.
66 template<class _T1
, class _T2
>
69 typedef _T1 first_type
; ///< @c first_type is the first bound type
70 typedef _T2 second_type
; ///< @c second_type is the second bound type
72 _T1 first
; ///< @c first is a copy of the first object
73 _T2 second
; ///< @c second is a copy of the second object
75 // _GLIBCXX_RESOLVE_LIB_DEFECTS
76 // 265. std::pair::pair() effects overly restrictive
77 /** The default constructor creates @c first and @c second using their
78 * respective default constructors. */
80 : first(), second() { }
82 /** Two objects may be passed to a @c pair constructor to be copied. */
83 pair(const _T1
& __a
, const _T2
& __b
)
84 : first(__a
), second(__b
) { }
86 #ifdef __GXX_EXPERIMENTAL_CXX0X__
87 template<class _U1
, class _U2
>
88 pair(_U1
&& __x
, _U2
&& __y
)
89 : first(std::forward
<_U1
>(__x
)),
90 second(std::forward
<_U2
>(__y
)) { }
93 : first(std::move(__p
.first
)),
94 second(std::move(__p
.second
)) { }
97 /** There is also a templated copy ctor for the @c pair class itself. */
98 template<class _U1
, class _U2
>
99 pair(const pair
<_U1
, _U2
>& __p
)
101 second(__p
.second
) { }
103 #ifdef __GXX_EXPERIMENTAL_CXX0X__
104 template<class _U1
, class _U2
>
105 pair(pair
<_U1
, _U2
>&& __p
)
106 : first(std::move(__p
.first
)),
107 second(std::move(__p
.second
)) { }
109 // http://gcc.gnu.org/ml/libstdc++/2007-08/msg00052.html
110 template<class _U1
, class _Arg0
, class... _Args
>
111 pair(_U1
&& __x
, _Arg0
&& __arg0
, _Args
&&... __args
)
112 : first(std::forward
<_U1
>(__x
)),
113 second(std::forward
<_Arg0
>(__arg0
),
114 std::forward
<_Args
>(__args
)...) { }
117 operator=(pair
&& __p
)
119 first
= std::move(__p
.first
);
120 second
= std::move(__p
.second
);
124 template<class _U1
, class _U2
>
126 operator=(pair
<_U1
, _U2
>&& __p
)
128 first
= std::move(__p
.first
);
129 second
= std::move(__p
.second
);
137 swap(first
, __p
.first
);
138 swap(second
, __p
.second
);
143 /// Two pairs of the same type are equal iff their members are equal.
144 template<class _T1
, class _T2
>
146 operator==(const pair
<_T1
, _T2
>& __x
, const pair
<_T1
, _T2
>& __y
)
147 { return __x
.first
== __y
.first
&& __x
.second
== __y
.second
; }
149 /// <http://gcc.gnu.org/onlinedocs/libstdc++/manual/utilities.html>
150 template<class _T1
, class _T2
>
152 operator<(const pair
<_T1
, _T2
>& __x
, const pair
<_T1
, _T2
>& __y
)
153 { return __x
.first
< __y
.first
154 || (!(__y
.first
< __x
.first
) && __x
.second
< __y
.second
); }
156 /// Uses @c operator== to find the result.
157 template<class _T1
, class _T2
>
159 operator!=(const pair
<_T1
, _T2
>& __x
, const pair
<_T1
, _T2
>& __y
)
160 { return !(__x
== __y
); }
162 /// Uses @c operator< to find the result.
163 template<class _T1
, class _T2
>
165 operator>(const pair
<_T1
, _T2
>& __x
, const pair
<_T1
, _T2
>& __y
)
166 { return __y
< __x
; }
168 /// Uses @c operator< to find the result.
169 template<class _T1
, class _T2
>
171 operator<=(const pair
<_T1
, _T2
>& __x
, const pair
<_T1
, _T2
>& __y
)
172 { return !(__y
< __x
); }
174 /// Uses @c operator< to find the result.
175 template<class _T1
, class _T2
>
177 operator>=(const pair
<_T1
, _T2
>& __x
, const pair
<_T1
, _T2
>& __y
)
178 { return !(__x
< __y
); }
180 #ifdef __GXX_EXPERIMENTAL_CXX0X__
181 /// See std::pair::swap().
182 // Note: no std::swap overloads in C++03 mode, this has performance
183 // implications, see, eg, libstdc++/38466.
184 template<class _T1
, class _T2
>
186 swap(pair
<_T1
, _T2
>& __x
, pair
<_T1
, _T2
>& __y
)
189 template<class _T1
, class _T2
>
191 swap(pair
<_T1
, _T2
>&& __x
, pair
<_T1
, _T2
>& __y
)
194 template<class _T1
, class _T2
>
196 swap(pair
<_T1
, _T2
>& __x
, pair
<_T1
, _T2
>&& __y
)
201 * @brief A convenience wrapper for creating a pair from two objects.
202 * @param x The first object.
203 * @param y The second object.
204 * @return A newly-constructed pair<> object of the appropriate type.
206 * The standard requires that the objects be passed by reference-to-const,
207 * but LWG issue #181 says they should be passed by const value. We follow
208 * the LWG by default.
210 // _GLIBCXX_RESOLVE_LIB_DEFECTS
211 // 181. make_pair() unintended behavior
212 #ifndef __GXX_EXPERIMENTAL_CXX0X__
213 template<class _T1
, class _T2
>
214 inline pair
<_T1
, _T2
>
215 make_pair(_T1 __x
, _T2 __y
)
216 { return pair
<_T1
, _T2
>(__x
, __y
); }
218 template<typename _Tp
>
219 class reference_wrapper
;
221 // Helper which adds a reference to a type when given a reference_wrapper
222 template<typename _Tp
>
223 struct __strip_reference_wrapper
228 template<typename _Tp
>
229 struct __strip_reference_wrapper
<reference_wrapper
<_Tp
> >
234 template<typename _Tp
>
235 struct __strip_reference_wrapper
<const reference_wrapper
<_Tp
> >
240 template<typename _Tp
>
241 struct __decay_and_strip
243 typedef typename __strip_reference_wrapper
<
244 typename decay
<_Tp
>::type
>::__type __type
;
248 template<class _T1
, class _T2
>
249 inline pair
<typename __decay_and_strip
<_T1
>::__type
,
250 typename __decay_and_strip
<_T2
>::__type
>
251 make_pair(_T1
&& __x
, _T2
&& __y
)
253 return pair
<typename __decay_and_strip
<_T1
>::__type
,
254 typename __decay_and_strip
<_T2
>::__type
>
255 (std::forward
<_T1
>(__x
), std::forward
<_T2
>(__y
));
259 _GLIBCXX_END_NAMESPACE
261 #endif /* _STL_PAIR_H */