williamr@2: //-----------------------------------------------------------------------------
williamr@2: // boost variant/detail/backup_holder.hpp header file
williamr@2: // See http://www.boost.org for updates, documentation, and revision history.
williamr@2: //-----------------------------------------------------------------------------
williamr@2: //
williamr@2: // Copyright (c) 2003
williamr@2: // Eric Friedman
williamr@2: //
williamr@2: // Distributed under the Boost Software License, Version 1.0. (See
williamr@2: // accompanying file LICENSE_1_0.txt or copy at
williamr@2: // http://www.boost.org/LICENSE_1_0.txt)
williamr@2: 
williamr@2: #ifndef BOOST_VARIANT_DETAIL_BACKUP_HOLDER_HPP
williamr@2: #define BOOST_VARIANT_DETAIL_BACKUP_HOLDER_HPP
williamr@2: 
williamr@2: #include "boost/assert.hpp"
williamr@2: 
williamr@2: namespace boost {
williamr@2: namespace detail { namespace variant {
williamr@2: 
williamr@2: template <typename T>
williamr@2: class backup_holder
williamr@2: {
williamr@2: private: // representation
williamr@2: 
williamr@2:     T* backup_;
williamr@2: 
williamr@2: public: // structors
williamr@2: 
williamr@2:     ~backup_holder()
williamr@2:     {
williamr@2:         delete backup_;
williamr@2:     }
williamr@2: 
williamr@2:     explicit backup_holder(T* backup)
williamr@2:         : backup_(backup)
williamr@2:     {
williamr@2:     }
williamr@2: 
williamr@2:     backup_holder(const backup_holder&);
williamr@2: 
williamr@2: public: // modifiers
williamr@2: 
williamr@2:     backup_holder& operator=(const backup_holder& rhs)
williamr@2:     {
williamr@2:         *backup_ = rhs.get();
williamr@2:         return *this;
williamr@2:     }
williamr@2: 
williamr@2:     backup_holder& operator=(const T& rhs)
williamr@2:     {
williamr@2:         *backup_ = rhs;
williamr@2:         return *this;
williamr@2:     }
williamr@2: 
williamr@2:     void swap(backup_holder& rhs)
williamr@2:     {
williamr@2:         T* tmp = rhs.backup_;
williamr@2:         rhs.backup_ = this->backup_;
williamr@2:         this->backup_ = tmp;
williamr@2:     }
williamr@2: 
williamr@2: public: // queries
williamr@2: 
williamr@2:     T& get()
williamr@2:     {
williamr@2:         return *backup_;
williamr@2:     }
williamr@2: 
williamr@2:     const T& get() const
williamr@2:     {
williamr@2:         return *backup_;
williamr@2:     }
williamr@2: 
williamr@2: };
williamr@2: 
williamr@2: template <typename T>
williamr@2: backup_holder<T>::backup_holder(const backup_holder&)
williamr@2:     : backup_(0)
williamr@2: {
williamr@2:     // not intended for copy, but do not want to prohibit syntactically
williamr@2:     BOOST_ASSERT(false);
williamr@2: }
williamr@2: 
williamr@2: template <typename T>
williamr@2: void swap(backup_holder<T>& lhs, backup_holder<T>& rhs)
williamr@2: {
williamr@2:     lhs.swap(rhs);
williamr@2: }
williamr@2: 
williamr@2: }} // namespace detail::variant
williamr@2: } // namespace boost
williamr@2: 
williamr@2: #endif // BOOST_VARIANT_DETAIL_BACKUP_HOLDER_HPP