1 //-----------------------------------------------------------------------------
2 // boost variant/detail/backup_holder.hpp header file
3 // See http://www.boost.org for updates, documentation, and revision history.
4 //-----------------------------------------------------------------------------
5 //
6 // Copyright (c) 2003
7 // Eric Friedman
8 //
9 // Distributed under the Boost Software License, Version 1.0. (See
10 // accompanying file LICENSE_1_0.txt or copy at
11 // http://www.boost.org/LICENSE_1_0.txt)
12 
13 #ifndef BOOST_VARIANT_DETAIL_BACKUP_HOLDER_HPP
14 #define BOOST_VARIANT_DETAIL_BACKUP_HOLDER_HPP
15 
16 #include <boost/config.hpp>
17 #include <boost/assert.hpp>
18 
19 namespace boost {
20 namespace detail { namespace variant {
21 
22 template <typename T>
23 class backup_holder
24 {
25 private: // representation
26 
27     T* backup_;
28 
29 public: // structors
30 
~backup_holder()31     ~backup_holder() BOOST_NOEXCEPT
32     {
33         delete backup_;
34     }
35 
backup_holder(T * backup)36     explicit backup_holder(T* backup) BOOST_NOEXCEPT
37         : backup_(backup)
38     {
39     }
40 
41     backup_holder(const backup_holder&);
42 
43 public: // modifiers
44 
operator =(const backup_holder & rhs)45     backup_holder& operator=(const backup_holder& rhs)
46     {
47         *backup_ = rhs.get();
48         return *this;
49     }
50 
operator =(const T & rhs)51     backup_holder& operator=(const T& rhs)
52     {
53         *backup_ = rhs;
54         return *this;
55     }
56 
swap(backup_holder & rhs)57     void swap(backup_holder& rhs) BOOST_NOEXCEPT
58     {
59         T* tmp = rhs.backup_;
60         rhs.backup_ = this->backup_;
61         this->backup_ = tmp;
62     }
63 
64 public: // queries
65 
get()66     T& get() BOOST_NOEXCEPT
67     {
68         return *backup_;
69     }
70 
get() const71     const T& get() const BOOST_NOEXCEPT
72     {
73         return *backup_;
74     }
75 
76 };
77 
78 template <typename T>
backup_holder(const backup_holder &)79 backup_holder<T>::backup_holder(const backup_holder&)
80     : backup_(0)
81 {
82     // not intended for copy, but do not want to prohibit syntactically
83     BOOST_ASSERT(false);
84 }
85 
86 template <typename T>
swap(backup_holder<T> & lhs,backup_holder<T> & rhs)87 void swap(backup_holder<T>& lhs, backup_holder<T>& rhs) BOOST_NOEXCEPT
88 {
89     lhs.swap(rhs);
90 }
91 
92 }} // namespace detail::variant
93 } // namespace boost
94 
95 #endif // BOOST_VARIANT_DETAIL_BACKUP_HOLDER_HPP
96