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>
optional_swapboost::optional_detail::swap_selector29 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>
optional_swapboost::optional_detail::swap_selector66 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>
swap(optional<T> & x,optional<T> & y)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
118