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    *  @brief Move unless it could throw and the type is copyable.
  87    *  @ingroup utilities
  88    *  @param  __x  A thing of arbitrary type.
  89    *  @return Same, possibly moved.
  90    */
  91   template<typename _Tp>
  92     inline typename
  93     conditional<(!is_nothrow_move_constructible<_Tp>::value
  94                  && is_copy_constructible<_Tp>::value),
  95                 const _Tp&, _Tp&&>::type
  96     move_if_noexcept(_Tp& __x) noexcept
  97     { return std::move(__x); }
  98
  99   /// declval, from type_traits.
 100
 101   /**
 102    *  @brief Returns the actual address of the object or function
 103    *         referenced by r, even in the presence of an overloaded
 104    *         operator&.
 105    *  @ingroup utilities
 106    *  @param  __r  Reference to an object or function.
 107    *  @return   The actual address.
 108   */
 109   template<typename _Tp>
 110     inline _Tp*
 111     addressof(_Tp& __r) noexcept
 112     { return std::__addressof(__r); }
 113
 114 _GLIBCXX_END_NAMESPACE_VERSION
 115 } // namespace
 116
 117 #define _GLIBCXX_MOVE(__val) std::move(__val)
 118 #define _GLIBCXX_FORWARD(_Tp, __val) std::forward<_Tp>(__val)
 119 #else
 120 #define _GLIBCXX_MOVE(__val) (__val)
 121 #define _GLIBCXX_FORWARD(_Tp, __val) (__val)
 122 #endif
 123
 124 namespace std _GLIBCXX_VISIBILITY(default)
 125 {
 126 _GLIBCXX_BEGIN_NAMESPACE_VERSION
 127
 128   /**
 129    *  @brief Swaps two values.
 130    *  @ingroup utilities
 131    *  @param  __a  A thing of arbitrary type.
 132    *  @param  __b  Another thing of arbitrary type.
 133    *  @return   Nothing.
 134   */
 135   template<typename _Tp>
 136     inline void
 137     swap(_Tp& __a, _Tp& __b)
 138 #ifdef __GXX_EXPERIMENTAL_CXX0X__
 139     noexcept(is_nothrow_move_constructible<_Tp>::value
 140              && is_nothrow_move_assignable<_Tp>::value)
 141 #endif
 142     {
 143       // concept requirements
 144       __glibcxx_function_requires(_SGIAssignableConcept<_Tp>)
 145
 146       _Tp __tmp = _GLIBCXX_MOVE(__a);
 147       __a = _GLIBCXX_MOVE(__b);
 148       __b = _GLIBCXX_MOVE(__tmp);
 149     }
 150
 151   // _GLIBCXX_RESOLVE_LIB_DEFECTS
 152   // DR 809. std::swap should be overloaded for array types.
 153   template<typename _Tp, size_t _Nm>
 154     inline void
 155     swap(_Tp (&__a)[_Nm], _Tp (&__b)[_Nm])
 156     // noexcept waits for c++/49045
 157     {
 158       for (size_t __n = 0; __n < _Nm; ++__n)
 159         swap(__a[__n], __b[__n]);
 160     }
 161
 162 _GLIBCXX_END_NAMESPACE_VERSION
 163 } // namespace
 164
 165 #endif /* _MOVE_H */