williamr@2: // Copyright 2002, Fernando Luis Cacciola Carballal.
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: // 21 Ago 2002 (Created) Fernando Cacciola
williamr@2: //
williamr@2: #ifndef BOOST_UTILITY_VALUE_INIT_21AGO2002_HPP
williamr@2: #define BOOST_UTILITY_VALUE_INIT_21AGO2002_HPP
williamr@2: 
williamr@2: #include "boost/detail/select_type.hpp"
williamr@2: #include "boost/type_traits/cv_traits.hpp"
williamr@2: 
williamr@2: namespace boost {
williamr@2: 
williamr@2: namespace vinit_detail {
williamr@2: 
williamr@2: template<class T>
williamr@2: class const_T_base
williamr@2: {
williamr@2:   protected :
williamr@2: 
williamr@2:    const_T_base() : x() {}
williamr@2: 
williamr@2:    T x ;
williamr@2: } ;
williamr@2: 
williamr@2: template<class T>
williamr@2: struct non_const_T_base
williamr@2: {
williamr@2:   protected :
williamr@2: 
williamr@2:    non_const_T_base() : x() {}
williamr@2: 
williamr@2:    mutable T x ;
williamr@2: } ;
williamr@2: 
williamr@2: template<class T>
williamr@2: struct select_base
williamr@2: {
williamr@2:   typedef typename
williamr@2:     boost::detail::if_true< ::boost::is_const<T>::value >
williamr@2:       ::template then< const_T_base<T>, non_const_T_base<T> >::type type ;
williamr@2: } ;
williamr@2: 
williamr@2: } // namespace vinit_detail
williamr@2: 
williamr@2: template<class T>
williamr@2: class value_initialized : private vinit_detail::select_base<T>::type
williamr@2: {
williamr@2:   public :
williamr@2: 
williamr@2:     value_initialized() {}
williamr@2: 
williamr@2:     operator T&() const { return this->x ; }
williamr@2: 
williamr@2:     T& data() const { return this->x ; }
williamr@2: 
williamr@2: } ;
williamr@2: 
williamr@2: template<class T>
williamr@2: T const& get ( value_initialized<T> const& x )
williamr@2: {
williamr@2:   return x.data() ;
williamr@2: }
williamr@2: template<class T>
williamr@2: T& get ( value_initialized<T>& x )
williamr@2: {
williamr@2:   return x.data() ;
williamr@2: }
williamr@2: 
williamr@2: } // namespace boost
williamr@2: 
williamr@2: 
williamr@2: #endif
williamr@2: