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1 : // Move, forward and identity for C++0x + swap -*- C++ -*-
2 :
3 : // Copyright (C) 2007-2014 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 bits/move.h
26 : * This is an internal header file, included by other library headers.
27 : * Do not attempt to use it directly. @headername{utility}
28 : */
29 :
30 : #ifndef _MOVE_H
31 : #define _MOVE_H 1
32 :
33 : #include <bits/c++config.h>
34 : #include <bits/concept_check.h>
35 :
36 : namespace std _GLIBCXX_VISIBILITY(default)
37 : {
38 : _GLIBCXX_BEGIN_NAMESPACE_VERSION
39 :
40 : // Used, in C++03 mode too, by allocators, etc.
41 : /**
42 : * @brief Same as C++11 std::addressof
43 : * @ingroup utilities
44 : */
45 : template<typename _Tp>
46 : inline _Tp*
47 209 : __addressof(_Tp& __r) _GLIBCXX_NOEXCEPT
48 : {
49 : return reinterpret_cast<_Tp*>
50 209 : (&const_cast<char&>(reinterpret_cast<const volatile char&>(__r)));
51 : }
52 :
53 : _GLIBCXX_END_NAMESPACE_VERSION
54 : } // namespace
55 :
56 : #if __cplusplus >= 201103L
57 : #include <type_traits> // Brings in std::declval too.
58 :
59 : namespace std _GLIBCXX_VISIBILITY(default)
60 : {
61 : _GLIBCXX_BEGIN_NAMESPACE_VERSION
62 :
63 : /**
64 : * @addtogroup utilities
65 : * @{
66 : */
67 :
68 : /**
69 : * @brief Forward an lvalue.
70 : * @return The parameter cast to the specified type.
71 : *
72 : * This function is used to implement "perfect forwarding".
73 : */
74 : template<typename _Tp>
75 : constexpr _Tp&&
76 1897 : forward(typename std::remove_reference<_Tp>::type& __t) noexcept
77 1897 : { return static_cast<_Tp&&>(__t); }
78 :
79 : /**
80 : * @brief Forward an rvalue.
81 : * @return The parameter cast to the specified type.
82 : *
83 : * This function is used to implement "perfect forwarding".
84 : */
85 : template<typename _Tp>
86 : constexpr _Tp&&
87 : forward(typename std::remove_reference<_Tp>::type&& __t) noexcept
88 : {
89 : static_assert(!std::is_lvalue_reference<_Tp>::value, "template argument"
90 : " substituting _Tp is an lvalue reference type");
91 : return static_cast<_Tp&&>(__t);
92 : }
93 :
94 : /**
95 : * @brief Convert a value to an rvalue.
96 : * @param __t A thing of arbitrary type.
97 : * @return The parameter cast to an rvalue-reference to allow moving it.
98 : */
99 : template<typename _Tp>
100 : constexpr typename std::remove_reference<_Tp>::type&&
101 1561 : move(_Tp&& __t) noexcept
102 1561 : { return static_cast<typename std::remove_reference<_Tp>::type&&>(__t); }
103 :
104 :
105 : template<typename _Tp>
106 : struct __move_if_noexcept_cond
107 : : public __and_<__not_<is_nothrow_move_constructible<_Tp>>,
108 : is_copy_constructible<_Tp>>::type { };
109 :
110 : /**
111 : * @brief Conditionally convert a value to an rvalue.
112 : * @param __x A thing of arbitrary type.
113 : * @return The parameter, possibly cast to an rvalue-reference.
114 : *
115 : * Same as std::move unless the type's move constructor could throw and the
116 : * type is copyable, in which case an lvalue-reference is returned instead.
117 : */
118 : template<typename _Tp>
119 : constexpr typename
120 : conditional<__move_if_noexcept_cond<_Tp>::value, const _Tp&, _Tp&&>::type
121 : move_if_noexcept(_Tp& __x) noexcept
122 : { return std::move(__x); }
123 :
124 : // declval, from type_traits.
125 :
126 : /**
127 : * @brief Returns the actual address of the object or function
128 : * referenced by r, even in the presence of an overloaded
129 : * operator&.
130 : * @param __r Reference to an object or function.
131 : * @return The actual address.
132 : */
133 : template<typename _Tp>
134 : inline _Tp*
135 : addressof(_Tp& __r) noexcept
136 : { return std::__addressof(__r); }
137 :
138 : /// @} group utilities
139 : _GLIBCXX_END_NAMESPACE_VERSION
140 : } // namespace
141 :
142 : #define _GLIBCXX_MOVE(__val) std::move(__val)
143 : #define _GLIBCXX_FORWARD(_Tp, __val) std::forward<_Tp>(__val)
144 : #else
145 : #define _GLIBCXX_MOVE(__val) (__val)
146 : #define _GLIBCXX_FORWARD(_Tp, __val) (__val)
147 : #endif
148 :
149 : namespace std _GLIBCXX_VISIBILITY(default)
150 : {
151 : _GLIBCXX_BEGIN_NAMESPACE_VERSION
152 :
153 : /**
154 : * @addtogroup utilities
155 : * @{
156 : */
157 :
158 : /**
159 : * @brief Swaps two values.
160 : * @param __a A thing of arbitrary type.
161 : * @param __b Another thing of arbitrary type.
162 : * @return Nothing.
163 : */
164 : template<typename _Tp>
165 : inline void
166 391 : swap(_Tp& __a, _Tp& __b)
167 : #if __cplusplus >= 201103L
168 : noexcept(__and_<is_nothrow_move_constructible<_Tp>,
169 : is_nothrow_move_assignable<_Tp>>::value)
170 : #endif
171 : {
172 : // concept requirements
173 : __glibcxx_function_requires(_SGIAssignableConcept<_Tp>)
174 :
175 391 : _Tp __tmp = _GLIBCXX_MOVE(__a);
176 391 : __a = _GLIBCXX_MOVE(__b);
177 391 : __b = _GLIBCXX_MOVE(__tmp);
178 391 : }
179 :
180 : // _GLIBCXX_RESOLVE_LIB_DEFECTS
181 : // DR 809. std::swap should be overloaded for array types.
182 : /// Swap the contents of two arrays.
183 : template<typename _Tp, size_t _Nm>
184 : inline void
185 : swap(_Tp (&__a)[_Nm], _Tp (&__b)[_Nm])
186 : #if __cplusplus >= 201103L
187 : noexcept(noexcept(swap(*__a, *__b)))
188 : #endif
189 : {
190 : for (size_t __n = 0; __n < _Nm; ++__n)
191 : swap(__a[__n], __b[__n]);
192 : }
193 :
194 : /// @} group utilities
195 : _GLIBCXX_END_NAMESPACE_VERSION
196 : } // namespace
197 :
198 : #endif /* _MOVE_H */
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