1 // Move, forward and identity for C++0x + swap -*- C++ -*-
3 // Copyright (C) 2007, 2008, 2009 Free Software Foundation, Inc.
5 // This file is part of the GNU ISO C++ Library. This library is free
6 // software; you can redistribute it and/or modify it under the
7 // terms of the GNU General Public License as published by the
8 // Free Software Foundation; either version 3, or (at your option)
11 // This library is distributed in the hope that it will be useful,
12 // but WITHOUT ANY WARRANTY; without even the implied warranty of
13 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 // GNU General Public License for more details.
16 // Under Section 7 of GPL version 3, you are granted additional
17 // permissions described in the GCC Runtime Library Exception, version
18 // 3.1, as published by the Free Software Foundation.
20 // You should have received a copy of the GNU General Public License and
21 // a copy of the GCC Runtime Library Exception along with this program;
22 // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
23 // <http://www.gnu.org/licenses/>.
26 * This is an internal header file, included by other library headers.
27 * You should not attempt to use it directly.
33 #include <bits/c++config.h>
35 #include <bits/concept_check.h>
37 #ifdef __GXX_EXPERIMENTAL_CXX0X__
38 #include <type_traits> // Brings in std::declval too.
40 _GLIBCXX_BEGIN_NAMESPACE(std
)
43 template<typename _Tp
>
49 /// forward (as per N2835)
50 /// Forward lvalues as rvalues.
51 template<typename _Tp
>
52 inline typename enable_if
<!is_lvalue_reference
<_Tp
>::value
, _Tp
&&>::type
53 forward(typename
std::identity
<_Tp
>::type
& __t
)
54 { return static_cast<_Tp
&&>(__t
); }
56 /// Forward rvalues as rvalues.
57 template<typename _Tp
>
58 inline typename enable_if
<!is_lvalue_reference
<_Tp
>::value
, _Tp
&&>::type
59 forward(typename
std::identity
<_Tp
>::type
&& __t
)
60 { return static_cast<_Tp
&&>(__t
); }
62 // Forward lvalues as lvalues.
63 template<typename _Tp
>
64 inline typename enable_if
<is_lvalue_reference
<_Tp
>::value
, _Tp
>::type
65 forward(typename
std::identity
<_Tp
>::type __t
)
68 // Prevent forwarding rvalues as const lvalues.
69 template<typename _Tp
>
70 inline typename enable_if
<is_lvalue_reference
<_Tp
>::value
, _Tp
>::type
71 forward(typename
std::remove_reference
<_Tp
>::type
&& __t
) = delete;
74 * @brief Move a value.
75 * @ingroup mutating_algorithms
76 * @param __t A thing of arbitrary type.
77 * @return Same, moved.
79 template<typename _Tp
>
80 inline typename
std::remove_reference
<_Tp
>::type
&&
82 { return static_cast<typename
std::remove_reference
<_Tp
>::type
&&>(__t
); }
84 /// declval, from type_traits.
86 _GLIBCXX_END_NAMESPACE
88 #define _GLIBCXX_MOVE(_Tp) std::move(_Tp)
89 #define _GLIBCXX_FORWARD(_Tp, __val) std::forward<_Tp>(__val)
91 #define _GLIBCXX_MOVE(_Tp) (_Tp)
92 #define _GLIBCXX_FORWARD(_Tp, __val) (__val)
95 _GLIBCXX_BEGIN_NAMESPACE(std
)
98 * @brief Swaps two values.
99 * @ingroup mutating_algorithms
100 * @param __a A thing of arbitrary type.
101 * @param __b Another thing of arbitrary type.
104 template<typename _Tp
>
106 swap(_Tp
& __a
, _Tp
& __b
)
108 // concept requirements
109 __glibcxx_function_requires(_SGIAssignableConcept
<_Tp
>)
111 _Tp __tmp
= _GLIBCXX_MOVE(__a
);
112 __a
= _GLIBCXX_MOVE(__b
);
113 __b
= _GLIBCXX_MOVE(__tmp
);
116 // _GLIBCXX_RESOLVE_LIB_DEFECTS
117 // DR 809. std::swap should be overloaded for array types.
118 template<typename _Tp
, size_t _Nm
>
120 swap(_Tp (&__a
)[_Nm
], _Tp (&__b
)[_Nm
])
122 for (size_t __n
= 0; __n
< _Nm
; ++__n
)
123 swap(__a
[__n
], __b
[__n
]);
126 _GLIBCXX_END_NAMESPACE