1 : // Move, forward and identity for C++0x + swap -*- C++ -*-
2 :
3 : // Copyright (C) 2007, 2008, 2009 Free Software Foundation, Inc.
4 : //
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)
9 : // any later version.
10 :
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.
15 :
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.
19 :
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/>.
24 :
25 : /** @file move.h
26 : * This is an internal header file, included by other library headers.
27 : * You should not attempt to use it directly.
28 : */
29 :
30 : #ifndef _MOVE_H
31 : #define _MOVE_H 1
32 :
33 : #include <bits/c++config.h>
34 : #include <cstddef>
35 : #include <bits/concept_check.h>
36 :
37 : #ifdef __GXX_EXPERIMENTAL_CXX0X__
38 : #include <type_traits> // Brings in std::declval too.
39 :
40 : _GLIBCXX_BEGIN_NAMESPACE(std)
41 :
42 : /// identity
43 : template<typename _Tp>
44 : struct identity
45 : {
46 : typedef _Tp type;
47 : };
48 :
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 148754942 : forward(typename std::identity<_Tp>::type& __t)
54 148754942 : { return static_cast<_Tp&&>(__t); }
55 :
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); }
61 :
62 : // Forward lvalues as lvalues.
63 : template<typename _Tp>
64 : inline typename enable_if<is_lvalue_reference<_Tp>::value, _Tp>::type
65 92927718 : forward(typename std::identity<_Tp>::type __t)
66 92927718 : { return __t; }
67 :
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;
72 :
73 : /**
74 : * @brief Move a value.
75 : * @ingroup mutating_algorithms
76 : * @param __t A thing of arbitrary type.
77 : * @return Same, moved.
78 : */
79 : template<typename _Tp>
80 : inline typename std::remove_reference<_Tp>::type&&
81 46869215 : move(_Tp&& __t)
82 46869215 : { return static_cast<typename std::remove_reference<_Tp>::type&&>(__t); }
83 :
84 : /// declval, from type_traits.
85 :
86 : _GLIBCXX_END_NAMESPACE
87 :
88 : #define _GLIBCXX_MOVE(_Tp) std::move(_Tp)
89 : #define _GLIBCXX_FORWARD(_Tp, __val) std::forward<_Tp>(__val)
90 : #else
91 : #define _GLIBCXX_MOVE(_Tp) (_Tp)
92 : #define _GLIBCXX_FORWARD(_Tp, __val) (__val)
93 : #endif
94 :
95 : _GLIBCXX_BEGIN_NAMESPACE(std)
96 :
97 : /**
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.
102 : * @return Nothing.
103 : */
104 : template<typename _Tp>
105 : inline void
106 6036357 : swap(_Tp& __a, _Tp& __b)
107 : {
108 : // concept requirements
109 : __glibcxx_function_requires(_SGIAssignableConcept<_Tp>)
110 :
111 6036357 : _Tp __tmp = _GLIBCXX_MOVE(__a);
112 6036357 : __a = _GLIBCXX_MOVE(__b);
113 6036357 : __b = _GLIBCXX_MOVE(__tmp);
114 6036357 : }
115 :
116 : // _GLIBCXX_RESOLVE_LIB_DEFECTS
117 : // DR 809. std::swap should be overloaded for array types.
118 : template<typename _Tp, size_t _Nm>
119 : inline void
120 : swap(_Tp (&__a)[_Nm], _Tp (&__b)[_Nm])
121 : {
122 : for (size_t __n = 0; __n < _Nm; ++__n)
123 : swap(__a[__n], __b[__n]);
124 : }
125 :
126 : _GLIBCXX_END_NAMESPACE
127 :
128 : #endif /* _MOVE_H */
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