Ticket #1884: make_shared.hpp

#ifndef BOOST_MAKE_SHARED_HPP_INCLUDED
#define BOOST_MAKE_SHARED_HPP_INCLUDED

//
//  make_shared.hpp
//
//  Copyright (c) 2007 Peter Dimov
//
//  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)
//
//  See http://www.boost.org/libs/smart_ptr/shared_ptr.htm for documentation.
//

#include <boost/config.hpp>
#include <boost/shared_ptr.hpp>
#include <boost/type_traits/type_with_alignment.hpp>
#include <boost/type_traits/alignment_of.hpp>
#include <cstddef>
#include <new>

namespace boost
{
namespace detail
{
    template< std::size_t N, std::size_t A > struct sp_aligned_storage
    {
        union type
        {
            char data_[ N ];
            typename boost::type_with_alignment< A >::type align_;
        };
    };

    template< class T > class sp_ms_deleter
    {
    private:

        typedef typename sp_aligned_storage< sizeof( T ), boost::alignment_of< T >::value >::type storage_type;

        bool initialized_;
        storage_type storage_;

    private:

        void destroy()
        {
            if( initialized_ )
            {
                reinterpret_cast< T* >( storage_.data_ )->~T();
                initialized_ = false;
            }
        }

    public:

        sp_ms_deleter(): initialized_( false )
        {
        }

        ~sp_ms_deleter()
        {
            destroy();
        }

        void operator()( T * )
        {
            destroy();
        }

        void * address()
        {
            return storage_.data_;
        }

        void set_initialized()
        {
            initialized_ = true;
        }
    };
} // namespace detail

// Zero-argument versions
//
// Used even when variadic templates are available because of the new T() vs new T issue

template< class T > boost::shared_ptr< T > make_shared()
{
    boost::shared_ptr< T > pt( static_cast< T* >( 0 ), detail::sp_ms_deleter< T >() );

    detail::sp_ms_deleter< T > * pd = boost::get_deleter< detail::sp_ms_deleter< T > >( pt );

    void * pv = pd->address();

    new( pv ) T();
    pd->set_initialized();

    return boost::shared_ptr< T >( pt, static_cast< T* >( pv ) );
}

template< class T, class A > boost::shared_ptr< T > allocate_shared( A const & a )
{
    boost::shared_ptr< T > pt( static_cast< T* >( 0 ), detail::sp_ms_deleter< T >(), a );

    detail::sp_ms_deleter< T > * pd = boost::get_deleter< detail::sp_ms_deleter< T > >( pt );

    void * pv = pd->address();

    new( pv ) T();
    pd->set_initialized();

    return boost::shared_ptr< T >( pt, static_cast< T* >( pv ) );
}

// FIXME: boost doesn't seem to have a compiler agnostic replacement for __STRICT_ANSI__
#if defined( BOOST_HAS_VARIADIC_TMPL ) && defined( BOOST_HAS_RVALUE_REFS ) && !defined( __STRICT_ANSI__ )

// Variadic templates, rvalue reference

template< class T> T forward( T t )
{
    return t;
}

template< class T, class... Args > boost::shared_ptr< T > make_shared( Args && ... args )
{
    boost::shared_ptr< T > pt( static_cast< T* >( 0 ), detail::sp_ms_deleter< T >() );

    detail::sp_ms_deleter< T > * pd = boost::get_deleter< detail::sp_ms_deleter< T > >( pt );

    void * pv = pd->address();

    new( pv ) T( forward<Args>( args )... );
    pd->set_initialized();

    return boost::shared_ptr< T >( pt, static_cast< T* >( pv ) );
}

template< class T, class A, class... Args > boost::shared_ptr< T > allocate_shared( A const & a, Args && ... args )
{
    boost::shared_ptr< T > pt( static_cast< T* >( 0 ), detail::sp_ms_deleter< T >(), a );

    detail::sp_ms_deleter< T > * pd = boost::get_deleter< detail::sp_ms_deleter< T > >( pt );

    void * pv = pd->address();

    new( pv ) T( forward<Args>( args )... );
    pd->set_initialized();

    return boost::shared_ptr< T >( pt, static_cast< T* >( pv ) );
}

#else

// C++03 version

template< class T, class A1 > boost::shared_ptr< T > make_shared( A1 const & a1 )
{
    boost::shared_ptr< T > pt( static_cast< T* >( 0 ), detail::sp_ms_deleter< T >() );

    detail::sp_ms_deleter< T > * pd = boost::get_deleter< detail::sp_ms_deleter< T > >( pt );

    void * pv = pd->address();

    new( pv ) T( a1 );
    pd->set_initialized();

    return boost::shared_ptr< T >( pt, static_cast< T* >( pv ) );
}

template< class T, class A, class A1 > boost::shared_ptr< T > allocate_shared( A const & a, A1 const & a1 )
{
    boost::shared_ptr< T > pt( static_cast< T* >( 0 ), detail::sp_ms_deleter< T >(), a );

    detail::sp_ms_deleter< T > * pd = boost::get_deleter< detail::sp_ms_deleter< T > >( pt );

    void * pv = pd->address();

    new( pv ) T( a1 );
    pd->set_initialized();

    return boost::shared_ptr< T >( pt, static_cast< T* >( pv ) );
}

template< class T, class A1, class A2 > boost::shared_ptr< T > make_shared( A1 const & a1, A2 const & a2 )
{
    boost::shared_ptr< T > pt( static_cast< T* >( 0 ), detail::sp_ms_deleter< T >() );

    detail::sp_ms_deleter< T > * pd = boost::get_deleter< detail::sp_ms_deleter< T > >( pt );

    void * pv = pd->address();

    new( pv ) T( a1, a2 );
    pd->set_initialized();

    return boost::shared_ptr< T >( pt, static_cast< T* >( pv ) );
}

template< class T, class A, class A1, class A2 > boost::shared_ptr< T > allocate_shared( A const & a, A1 const & a1, A2 const & a2 )
{
    boost::shared_ptr< T > pt( static_cast< T* >( 0 ), detail::sp_ms_deleter< T >(), a );

    detail::sp_ms_deleter< T > * pd = boost::get_deleter< detail::sp_ms_deleter< T > >( pt );

    void * pv = pd->address();

    new( pv ) T( a1, a2 );
    pd->set_initialized();

    return boost::shared_ptr< T >( pt, static_cast< T* >( pv ) );
}

template< class T, class A1, class A2, class A3 > boost::shared_ptr< T > make_shared( A1 const & a1, A2 const & a2, A3 const & a3 )
{
    boost::shared_ptr< T > pt( static_cast< T* >( 0 ), detail::sp_ms_deleter< T >() );

    detail::sp_ms_deleter< T > * pd = boost::get_deleter< detail::sp_ms_deleter< T > >( pt );

    void * pv = pd->address();

    new( pv ) T( a1, a2, a3 );
    pd->set_initialized();

    return boost::shared_ptr< T >( pt, static_cast< T* >( pv ) );
}

template< class T, class A, class A1, class A2, class A3 > boost::shared_ptr< T > allocate_shared( A const & a, A1 const & a1, A2 const & a2, A3 const & a3 )
{
    boost::shared_ptr< T > pt( static_cast< T* >( 0 ), detail::sp_ms_deleter< T >(), a );

    detail::sp_ms_deleter< T > * pd = boost::get_deleter< detail::sp_ms_deleter< T > >( pt );

    void * pv = pd->address();

    new( pv ) T( a1, a2, a3 );
    pd->set_initialized();

    return boost::shared_ptr< T >( pt, static_cast< T* >( pv ) );
}

template< class T, class A1, class A2, class A3, class A4 > boost::shared_ptr< T > make_shared( A1 const & a1, A2 const & a2, A3 const & a3, A4 const & a4 )
{
    boost::shared_ptr< T > pt( static_cast< T* >( 0 ), detail::sp_ms_deleter< T >() );

    detail::sp_ms_deleter< T > * pd = boost::get_deleter< detail::sp_ms_deleter< T > >( pt );

    void * pv = pd->address();

    new( pv ) T( a1, a2, a3, a4 );
    pd->set_initialized();

    return boost::shared_ptr< T >( pt, static_cast< T* >( pv ) );
}

template< class T, class A, class A1, class A2, class A3, class A4 > boost::shared_ptr< T > allocate_shared( A const & a, A1 const & a1, A2 const & a2, A3 const & a3, A4 const & a4 )
{
    boost::shared_ptr< T > pt( static_cast< T* >( 0 ), detail::sp_ms_deleter< T >(), a );

    detail::sp_ms_deleter< T > * pd = boost::get_deleter< detail::sp_ms_deleter< T > >( pt );

    void * pv = pd->address();

    new( pv ) T( a1, a2, a3, a4 );
    pd->set_initialized();

    return boost::shared_ptr< T >( pt, static_cast< T* >( pv ) );
}

#endif

}   // namespace boost

#endif // #ifndef BOOST_MAKE_SHARED_HPP_INCLUDED