libstdc++-v3/include/bits/move.h

   1 // Move, forward and identity for C++0x + swap -*- C++ -*-
   2
   3 // Copyright (C) 2007, 2008, 2009, 2010, 2011 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   template<typename _Tp>
  42     inline _Tp*
  43     __addressof(_Tp& __r) _GLIBCXX_NOEXCEPT
  44     {
  45       return reinterpret_cast<_Tp*>
  46         (&const_cast<char&>(reinterpret_cast<const volatile char&>(__r)));
  47     }
  48
  49 _GLIBCXX_END_NAMESPACE_VERSION
  50 } // namespace
  51
  52 #ifdef __GXX_EXPERIMENTAL_CXX0X__
  53 #include <type_traits> // Brings in std::declval too.
  54
  55 namespace std _GLIBCXX_VISIBILITY(default)
  56 {
  57 _GLIBCXX_BEGIN_NAMESPACE_VERSION
  58
  59   /// forward (as per N3143)
  60   template<typename _Tp>
  61     inline _Tp&&
  62     forward(typename std::remove_reference<_Tp>::type& __t) noexcept
  63     { return static_cast<_Tp&&>(__t); }
  64
  65   template<typename _Tp>
  66     inline _Tp&&
  67     forward(typename std::remove_reference<_Tp>::type&& __t) noexcept
  68     {
  69       static_assert(!std::is_lvalue_reference<_Tp>::value, "template argument"
  70                     " substituting _Tp is an lvalue reference type");
  71       return static_cast<_Tp&&>(__t);
  72     }
  73
  74   /**
  75    *  @brief Move a value.
  76    *  @ingroup utilities
  77    *  @param  __t  A thing of arbitrary type.
  78    *  @return Same, moved.
  79   */
  80   template<typename _Tp>
  81     inline typename std::remove_reference<_Tp>::type&&
  82     move(_Tp&& __t) noexcept
  83     { return static_cast<typename std::remove_reference<_Tp>::type&&>(__t); }
  84
  85
  86   template<typename _Tp>
  87     struct __move_if_noexcept_cond
  88     : public __and_<__not_<is_nothrow_move_constructible<_Tp>>,
  89                     is_copy_constructible<_Tp>>::type { };
  90
  91   /**
  92    *  @brief Move unless it could throw and the type is copyable.
  93    *  @ingroup utilities
  94    *  @param  __x  A thing of arbitrary type.
  95    *  @return Same, possibly moved.
  96    */
  97   template<typename _Tp>
  98     inline typename
  99     conditional<__move_if_noexcept_cond<_Tp>::value, const _Tp&, _Tp&&>::type
 100     move_if_noexcept(_Tp& __x) noexcept
 101     { return std::move(__x); }
 102
 103   /// declval, from type_traits.
 104
 105   /**
 106    *  @brief Returns the actual address of the object or function
 107    *         referenced by r, even in the presence of an overloaded
 108    *         operator&.
 109    *  @ingroup utilities
 110    *  @param  __r  Reference to an object or function.
 111    *  @return   The actual address.
 112   */
 113   template<typename _Tp>
 114     inline _Tp*
 115     addressof(_Tp& __r) noexcept
 116     { return std::__addressof(__r); }
 117
 118 _GLIBCXX_END_NAMESPACE_VERSION
 119 } // namespace
 120
 121 #define _GLIBCXX_MOVE(__val) std::move(__val)
 122 #define _GLIBCXX_FORWARD(_Tp, __val) std::forward<_Tp>(__val)
 123 #else
 124 #define _GLIBCXX_MOVE(__val) (__val)
 125 #define _GLIBCXX_FORWARD(_Tp, __val) (__val)
 126 #endif
 127
 128 namespace std _GLIBCXX_VISIBILITY(default)
 129 {
 130 _GLIBCXX_BEGIN_NAMESPACE_VERSION
 131
 132   /**
 133    *  @brief Swaps two values.
 134    *  @ingroup utilities
 135    *  @param  __a  A thing of arbitrary type.
 136    *  @param  __b  Another thing of arbitrary type.
 137    *  @return   Nothing.
 138   */
 139   template<typename _Tp>
 140     inline void
 141     swap(_Tp& __a, _Tp& __b)
 142 #ifdef __GXX_EXPERIMENTAL_CXX0X__
 143     noexcept(__and_<is_nothrow_move_constructible<_Tp>,
 144                     is_nothrow_move_assignable<_Tp>>::value)
 145 #endif
 146     {
 147       // concept requirements
 148       __glibcxx_function_requires(_SGIAssignableConcept<_Tp>)
 149
 150       _Tp __tmp = _GLIBCXX_MOVE(__a);
 151       __a = _GLIBCXX_MOVE(__b);
 152       __b = _GLIBCXX_MOVE(__tmp);
 153     }
 154
 155 #ifdef __GXX_EXPERIMENTAL_CXX0X__
 156   // To work around c++/49045.
 157   template<typename _Tp>
 158     struct __is_nothrow_swappable
 159     { static const bool value = noexcept(swap(std::declval<_Tp&>(),
 160                                               std::declval<_Tp&>())); };
 161 #endif
 162
 163   // _GLIBCXX_RESOLVE_LIB_DEFECTS
 164   // DR 809. std::swap should be overloaded for array types.
 165   template<typename _Tp, size_t _Nm>
 166     inline void
 167     swap(_Tp (&__a)[_Nm], _Tp (&__b)[_Nm])
 168 #ifdef __GXX_EXPERIMENTAL_CXX0X__
 169     noexcept(__is_nothrow_swappable<_Tp>::value)
 170 #endif
 171     {
 172       for (size_t __n = 0; __n < _Nm; ++__n)
 173         swap(__a[__n], __b[__n]);
 174     }
 175
 176 _GLIBCXX_END_NAMESPACE_VERSION
 177 } // namespace
 178
 179 #endif /* _MOVE_H */