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 __addressof(_Tp& __r) _GLIBCXX_NOEXCEPT 48 { 49 return reinterpret_cast<_Tp*> 50 (&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 forward(typename std::remove_reference<_Tp>::type& __t) noexcept 77 { 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 move(_Tp&& __t) noexcept 102 { 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 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 _Tp __tmp = _GLIBCXX_MOVE(__a); 176 __a = _GLIBCXX_MOVE(__b); 177 __b = _GLIBCXX_MOVE(__tmp); 178 } 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 */ 199
