boost/type_traits/aligned_storage.hpp

//-----------------------------------------------------------------------------
// boost aligned_storage.hpp header file
// See http://www.boost.org for updates, documentation, and revision history.
//-----------------------------------------------------------------------------
//
// Copyright (c) 2002-2003
// Eric Friedman, Itay Maman
//
// Distributed under the Boost Software License, Version 1.0. (See
// accompanying file LICENSE_1_0.txt or copy at
// http://www.boost.org/LICENSE_1_0.txt)
#ifndef BOOST_TT_ALIGNED_STORAGE_HPP
#define BOOST_TT_ALIGNED_STORAGE_HPP
#include <cstddef> // for std::size_t
#include <boost/config.hpp>
#include <boost/detail/workaround.hpp>
#include <boost/type_traits/alignment_of.hpp>
#include <boost/type_traits/type_with_alignment.hpp>
#include <boost/type_traits/is_pod.hpp>
#include <boost/type_traits/conditional.hpp>
namespace boost {
namespace detail { namespace aligned_storage {
BOOST_STATIC_CONSTANT(
      std::size_t
    , alignment_of_max_align = ::boost::alignment_of<boost::detail::max_align>::value
    );
//
// To be TR1 conforming this must be a POD type:
//
template <
      std::size_t size_
    , std::size_t alignment_
>
struct aligned_storage_imp
{
    union data_t
    {
        char buf[size_];
        typename ::boost::type_with_alignment<alignment_>::type align_;
    } data_;
    void* address() const { return const_cast<aligned_storage_imp*>(this); }
};
template <std::size_t size>
struct aligned_storage_imp<size, std::size_t(-1)>
{
   union data_t
   {
      char buf[size];
      ::boost::detail::max_align align_;
   } data_;
   void* address() const { return const_cast<aligned_storage_imp*>(this); }
};
template< std::size_t alignment_ >
struct aligned_storage_imp<0u,alignment_>
{
    /* intentionally empty */
    void* address() const { return 0; }
};
}} // namespace detail::aligned_storage
template <
      std::size_t size_
    , std::size_t alignment_ = std::size_t(-1)
>
class aligned_storage : 
#ifndef __BORLANDC__
   private 
#else
   public
#endif
   ::boost::detail::aligned_storage::aligned_storage_imp<size_, alignment_> 
{
 
public: // constants
    typedef ::boost::detail::aligned_storage::aligned_storage_imp<size_, alignment_> type;
    BOOST_STATIC_CONSTANT(
          std::size_t
        , size = size_
        );
    BOOST_STATIC_CONSTANT(
          std::size_t
        , alignment = (
              alignment_ == std::size_t(-1)
            ? ::boost::detail::aligned_storage::alignment_of_max_align
            : alignment_
            )
        );
private: // noncopyable
    aligned_storage(const aligned_storage&);
    aligned_storage& operator=(const aligned_storage&);
public: // structors
    aligned_storage()
    {
    }
    ~aligned_storage()
    {
    }
public: // accessors
    void* address()
    {
        return static_cast<type*>(this)->address();
    }
    const void* address() const
    {
        return static_cast<const type*>(this)->address();
    }
};
//
// Make sure that is_pod recognises aligned_storage<>::type
// as a POD (Note that aligned_storage<> itself is not a POD):
//
template <std::size_t size_, std::size_t alignment_>
struct is_pod< ::boost::detail::aligned_storage::aligned_storage_imp<size_, alignment_> > : public true_type{};
} // namespace boost
#endif // BOOST_ALIGNED_STORAGE_HPP