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, defined in <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