Chris@16: // (C) Copyright 2002-2008, Fernando Luis Cacciola Carballal.
Chris@16: //
Chris@16: // Distributed under the Boost Software License, Version 1.0. (See
Chris@16: // accompanying file LICENSE_1_0.txt or copy at
Chris@16: // http://www.boost.org/LICENSE_1_0.txt)
Chris@16: //
Chris@16: // 21 Ago 2002 (Created) Fernando Cacciola
Chris@16: // 24 Dec 2007 (Refactored and worked around various compiler bugs) Fernando Cacciola, Niels Dekker
Chris@16: // 23 May 2008 (Fixed operator= const issue, added initialized_value) Niels Dekker, Fernando Cacciola
Chris@16: // 21 Ago 2008 (Added swap) Niels Dekker, Fernando Cacciola
Chris@16: // 20 Feb 2009 (Fixed logical const-ness issues) Niels Dekker, Fernando Cacciola
Chris@16: // 03 Apr 2010 (Added initialized<T>, suggested by Jeffrey Hellrung, fixing #3472) Niels Dekker
Chris@16: // 30 May 2010 (Made memset call conditional, fixing #3869) Niels Dekker
Chris@16: //
Chris@16: #ifndef BOOST_UTILITY_VALUE_INIT_21AGO2002_HPP
Chris@16: #define BOOST_UTILITY_VALUE_INIT_21AGO2002_HPP
Chris@16: 
Chris@16: // Note: The implementation of boost::value_initialized had to deal with the
Chris@16: // fact that various compilers haven't fully implemented value-initialization.
Chris@16: // The constructor of boost::value_initialized<T> works around these compiler
Chris@16: // issues, by clearing the bytes of T, before constructing the T object it
Chris@16: // contains. More details on these issues are at libs/utility/value_init.htm
Chris@16: 
Chris@16: #include <boost/aligned_storage.hpp>
Chris@16: #include <boost/config.hpp> // For BOOST_NO_COMPLETE_VALUE_INITIALIZATION.
Chris@16: #include <boost/detail/workaround.hpp>
Chris@16: #include <boost/static_assert.hpp>
Chris@16: #include <boost/type_traits/cv_traits.hpp>
Chris@16: #include <boost/type_traits/alignment_of.hpp>
Chris@16: #include <boost/swap.hpp>
Chris@16: #include <cstring>
Chris@16: #include <new>
Chris@16: 
Chris@16: #ifdef BOOST_MSVC
Chris@16: #pragma warning(push)
Chris@16: // It is safe to ignore the following warning from MSVC 7.1 or higher:
Chris@16: // "warning C4351: new behavior: elements of array will be default initialized"
Chris@16: #pragma warning(disable: 4351)
Chris@16: // It is safe to ignore the following MSVC warning, which may pop up when T is 
Chris@16: // a const type: "warning C4512: assignment operator could not be generated".
Chris@16: #pragma warning(disable: 4512)
Chris@16: #endif
Chris@16: 
Chris@16: #ifdef BOOST_NO_COMPLETE_VALUE_INITIALIZATION
Chris@16:   // Implementation detail: The macro BOOST_DETAIL_VALUE_INIT_WORKAROUND_SUGGESTED 
Chris@16:   // suggests that a workaround should be applied, because of compiler issues 
Chris@16:   // regarding value-initialization.
Chris@16:   #define BOOST_DETAIL_VALUE_INIT_WORKAROUND_SUGGESTED
Chris@16: #endif
Chris@16: 
Chris@16: // Implementation detail: The macro BOOST_DETAIL_VALUE_INIT_WORKAROUND
Chris@16: // switches the value-initialization workaround either on or off.
Chris@16: #ifndef BOOST_DETAIL_VALUE_INIT_WORKAROUND
Chris@16:   #ifdef BOOST_DETAIL_VALUE_INIT_WORKAROUND_SUGGESTED
Chris@16:   #define BOOST_DETAIL_VALUE_INIT_WORKAROUND 1
Chris@16:   #else
Chris@16:   #define BOOST_DETAIL_VALUE_INIT_WORKAROUND 0
Chris@16:   #endif
Chris@16: #endif
Chris@16: 
Chris@16: namespace boost {
Chris@16: 
Chris@16: template<class T>
Chris@16: class initialized
Chris@16: {
Chris@16:   private :
Chris@16:     struct wrapper
Chris@16:     {
Chris@16: #if !BOOST_WORKAROUND(__BORLANDC__, BOOST_TESTED_AT(0x592))
Chris@16:       typename
Chris@16: #endif 
Chris@16:       remove_const<T>::type data;
Chris@16: 
Chris@101:       BOOST_GPU_ENABLED
Chris@16:       wrapper()
Chris@16:       :
Chris@16:       data()
Chris@16:       {
Chris@16:       }
Chris@16: 
Chris@101:       BOOST_GPU_ENABLED
Chris@16:       wrapper(T const & arg)
Chris@16:       :
Chris@16:       data(arg)
Chris@16:       {
Chris@16:       }
Chris@16:     };
Chris@16: 
Chris@16:     mutable
Chris@16: #if !BOOST_WORKAROUND(__BORLANDC__, BOOST_TESTED_AT(0x592))
Chris@16:       typename
Chris@16: #endif 
Chris@16:       aligned_storage<sizeof(wrapper), alignment_of<wrapper>::value>::type x;
Chris@16: 
Chris@101:     BOOST_GPU_ENABLED
Chris@16:     wrapper * wrapper_address() const
Chris@16:     {
Chris@16:       return static_cast<wrapper *>( static_cast<void*>(&x));
Chris@16:     }
Chris@16: 
Chris@16:   public :
Chris@16: 
Chris@101:     BOOST_GPU_ENABLED
Chris@16:     initialized()
Chris@16:     {
Chris@16: #if BOOST_DETAIL_VALUE_INIT_WORKAROUND
Chris@16:       std::memset(&x, 0, sizeof(x));
Chris@16: #endif
Chris@16:       new (wrapper_address()) wrapper();
Chris@16:     }
Chris@16: 
Chris@101:     BOOST_GPU_ENABLED
Chris@16:     initialized(initialized const & arg)
Chris@16:     {
Chris@16:       new (wrapper_address()) wrapper( static_cast<wrapper const &>(*(arg.wrapper_address())));
Chris@16:     }
Chris@16: 
Chris@101:     BOOST_GPU_ENABLED
Chris@16:     explicit initialized(T const & arg)
Chris@16:     {
Chris@16:       new (wrapper_address()) wrapper(arg);
Chris@16:     }
Chris@16: 
Chris@101:     BOOST_GPU_ENABLED
Chris@16:     initialized & operator=(initialized const & arg)
Chris@16:     {
Chris@16:       // Assignment is only allowed when T is non-const.
Chris@16:       BOOST_STATIC_ASSERT( ! is_const<T>::value );
Chris@16:       *wrapper_address() = static_cast<wrapper const &>(*(arg.wrapper_address()));
Chris@16:       return *this;
Chris@16:     }
Chris@16: 
Chris@101:     BOOST_GPU_ENABLED
Chris@16:     ~initialized()
Chris@16:     {
Chris@16:       wrapper_address()->wrapper::~wrapper();
Chris@16:     }
Chris@16: 
Chris@101:     BOOST_GPU_ENABLED
Chris@16:     T const & data() const
Chris@16:     {
Chris@16:       return wrapper_address()->data;
Chris@16:     }
Chris@16: 
Chris@101:     BOOST_GPU_ENABLED
Chris@16:     T& data()
Chris@16:     {
Chris@16:       return wrapper_address()->data;
Chris@16:     }
Chris@16: 
Chris@101:     BOOST_GPU_ENABLED
Chris@16:     void swap(initialized & arg)
Chris@16:     {
Chris@16:       ::boost::swap( this->data(), arg.data() );
Chris@16:     }
Chris@16: 
Chris@101:     BOOST_GPU_ENABLED
Chris@16:     operator T const &() const
Chris@16:     {
Chris@16:       return wrapper_address()->data;
Chris@16:     }
Chris@16: 
Chris@101:     BOOST_GPU_ENABLED
Chris@16:     operator T&()
Chris@16:     {
Chris@16:       return wrapper_address()->data;
Chris@16:     }
Chris@16: 
Chris@16: } ;
Chris@16: 
Chris@16: template<class T>
Chris@101: BOOST_GPU_ENABLED
Chris@16: T const& get ( initialized<T> const& x )
Chris@16: {
Chris@16:   return x.data() ;
Chris@16: }
Chris@16: 
Chris@16: template<class T>
Chris@101: BOOST_GPU_ENABLED
Chris@16: T& get ( initialized<T>& x )
Chris@16: {
Chris@16:   return x.data() ;
Chris@16: }
Chris@16: 
Chris@16: template<class T>
Chris@101: BOOST_GPU_ENABLED
Chris@16: void swap ( initialized<T> & lhs, initialized<T> & rhs )
Chris@16: {
Chris@16:   lhs.swap(rhs) ;
Chris@16: }
Chris@16: 
Chris@16: template<class T>
Chris@16: class value_initialized
Chris@16: {
Chris@16:   private :
Chris@16: 
Chris@16:     // initialized<T> does value-initialization by default.
Chris@16:     initialized<T> m_data;
Chris@16: 
Chris@16:   public :
Chris@16:     
Chris@101:     BOOST_GPU_ENABLED
Chris@16:     value_initialized()
Chris@16:     :
Chris@16:     m_data()
Chris@16:     { }
Chris@16:     
Chris@101:     BOOST_GPU_ENABLED
Chris@16:     T const & data() const
Chris@16:     {
Chris@16:       return m_data.data();
Chris@16:     }
Chris@16: 
Chris@101:     BOOST_GPU_ENABLED
Chris@16:     T& data()
Chris@16:     {
Chris@16:       return m_data.data();
Chris@16:     }
Chris@16: 
Chris@101:     BOOST_GPU_ENABLED
Chris@16:     void swap(value_initialized & arg)
Chris@16:     {
Chris@16:       m_data.swap(arg.m_data);
Chris@16:     }
Chris@16: 
Chris@101:     BOOST_GPU_ENABLED
Chris@16:     operator T const &() const
Chris@16:     {
Chris@16:       return m_data;
Chris@16:     }
Chris@16: 
Chris@101:     BOOST_GPU_ENABLED
Chris@16:     operator T&()
Chris@16:     {
Chris@16:       return m_data;
Chris@16:     }
Chris@16: } ;
Chris@16: 
Chris@16: 
Chris@16: template<class T>
Chris@101: BOOST_GPU_ENABLED
Chris@16: T const& get ( value_initialized<T> const& x )
Chris@16: {
Chris@16:   return x.data() ;
Chris@16: }
Chris@16: 
Chris@16: template<class T>
Chris@101: BOOST_GPU_ENABLED
Chris@16: T& get ( value_initialized<T>& x )
Chris@16: {
Chris@16:   return x.data() ;
Chris@16: }
Chris@16: 
Chris@16: template<class T>
Chris@101: BOOST_GPU_ENABLED
Chris@16: void swap ( value_initialized<T> & lhs, value_initialized<T> & rhs )
Chris@16: {
Chris@16:   lhs.swap(rhs) ;
Chris@16: }
Chris@16: 
Chris@16: 
Chris@16: class initialized_value_t
Chris@16: {
Chris@16:   public :
Chris@16:     
Chris@101:     template <class T> BOOST_GPU_ENABLED operator T() const
Chris@16:     {
Chris@16:       return initialized<T>().data();
Chris@16:     }
Chris@16: };
Chris@16: 
Chris@16: initialized_value_t const initialized_value = {} ;
Chris@16: 
Chris@16: 
Chris@16: } // namespace boost
Chris@16: 
Chris@16: #ifdef BOOST_MSVC
Chris@16: #pragma warning(pop)
Chris@16: #endif
Chris@16: 
Chris@16: #endif