ceph/src/boost/boost/optional/detail/optional_swap.hpp

   1 // Copyright (C) 2003, 2008 Fernando Luis Cacciola Carballal.
   2 // Copyright (C) 2015 Andrzej Krzemienski.
   3 //
   4 // Use, modification, and distribution is subject to the Boost Software
   5 // License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
   6 // http://www.boost.org/LICENSE_1_0.txt)
   7 //
   8 // See http://www.boost.org/libs/optional for documentation.
   9 //
  10 // You are welcome to contact the author at:
  11 //  akrzemi1@gmail.com
  12
  13 #ifndef BOOST_OPTIONAL_DETAIL_OPTIONAL_SWAP_AJK_28JAN2015_HPP
  14 #define BOOST_OPTIONAL_DETAIL_OPTIONAL_SWAP_AJK_28JAN2015_HPP
  15
  16 #include <boost/core/swap.hpp>
  17 #include <boost/optional/optional_fwd.hpp>
  18
  19 namespace boost {
  20
  21 namespace optional_detail {
  22
  23 template <bool use_default_constructor> struct swap_selector;
  24
  25 template <>
  26 struct swap_selector<true>
  27 {
  28     template <class T>
  29     static void optional_swap ( optional<T>& x, optional<T>& y )
  30     {
  31         const bool hasX = !!x;
  32         const bool hasY = !!y;
  33
  34         if ( !hasX && !hasY )
  35             return;
  36
  37         if( !hasX )
  38             x.emplace();
  39         else if ( !hasY )
  40             y.emplace();
  41
  42         // Boost.Utility.Swap will take care of ADL and workarounds for broken compilers
  43         boost::swap(x.get(), y.get());
  44
  45         if( !hasX )
  46             y = boost::none ;
  47         else if( !hasY )
  48             x = boost::none ;
  49     }
  50 };
  51
  52 #ifdef BOOST_OPTIONAL_DETAIL_MOVE
  53 # undef BOOST_OPTIONAL_DETAIL_MOVE
  54 #endif
  55
  56 #ifndef BOOST_OPTIONAL_DETAIL_NO_RVALUE_REFERENCES
  57 # define BOOST_OPTIONAL_DETAIL_MOVE(EXPR_) boost::move(EXPR_)
  58 #else
  59 # define BOOST_OPTIONAL_DETAIL_MOVE(EXPR_) EXPR_
  60 #endif
  61
  62 template <>
  63 struct swap_selector<false>
  64 {
  65     template <class T>
  66     static void optional_swap ( optional<T>& x, optional<T>& y )
  67     //BOOST_NOEXCEPT_IF(::boost::is_nothrow_move_constructible<T>::value && BOOST_NOEXCEPT_EXPR(boost::swap(*x, *y)))
  68     {
  69         if (x)
  70         {
  71             if (y)
  72             {
  73                 boost::swap(*x, *y);
  74             }
  75             else
  76             {
  77                 y = BOOST_OPTIONAL_DETAIL_MOVE(*x);
  78                 x = boost::none;
  79             }
  80         }
  81         else
  82         {
  83             if (y)
  84             {
  85                 x = BOOST_OPTIONAL_DETAIL_MOVE(*y);
  86                 y = boost::none;
  87             }
  88         }
  89     }
  90 };
  91
  92 } // namespace optional_detail
  93
  94 #if (!defined BOOST_NO_CXX11_RVALUE_REFERENCES) && (!defined BOOST_CONFIG_RESTORE_OBSOLETE_SWAP_IMPLEMENTATION)
  95
  96 template<class T>
  97 struct optional_swap_should_use_default_constructor : boost::false_type {} ;
  98
  99 #else
 100
 101 template<class T>
 102 struct optional_swap_should_use_default_constructor : has_nothrow_default_constructor<T> {} ;
 103
 104 #endif
 105
 106 template <class T>
 107 inline void swap ( optional<T>& x, optional<T>& y )
 108 //BOOST_NOEXCEPT_IF(::boost::is_nothrow_move_constructible<T>::value && BOOST_NOEXCEPT_EXPR(boost::swap(*x, *y)))
 109 {
 110     optional_detail::swap_selector<optional_swap_should_use_default_constructor<T>::value>::optional_swap(x, y);
 111 }
 112
 113 } // namespace boost
 114
 115 #undef BOOST_OPTIONAL_DETAIL_MOVE
 116
 117 #endif // header guard