//  boost polymorphic_pointer_cast.hpp header file  ----------------------------------------------//

//  (C) Copyright Boris Rasin and Antony Polukhin 2014-2015.

//  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/conversion for Documentation.

#ifndef BOOST_CONVERSION_POLYMORPHIC_POINTER_CAST_HPP

#define BOOST_CONVERSION_POLYMORPHIC_POINTER_CAST_HPP

# include <boost/config.hpp>

# include <boost/assert.hpp>

# include <boost/pointer_cast.hpp>

# include <boost/throw_exception.hpp>

# include <boost/utility/declval.hpp>

# ifdef BOOST_NO_CXX11_DECLTYPE

#   include <boost/typeof/typeof.hpp>

# endif

#ifdef BOOST_HAS_PRAGMA_ONCE

#   pragma once

#endif

namespace boost

{

//  See the documentation for descriptions of how to choose between

//  static_pointer_cast<>, dynamic_pointer_cast<>, polymorphic_pointer_cast<> and polymorphic_pointer_downcast<>

//  polymorphic_pointer_downcast  --------------------------------------------//

    //  BOOST_ASSERT() checked polymorphic downcast.  Crosscasts prohibited.

    //  Supports any type with static_pointer_cast/dynamic_pointer_cast functions:

    //  built-in pointers, std::shared_ptr, boost::shared_ptr, boost::intrusive_ptr, etc.

    //  WARNING: Because this cast uses BOOST_ASSERT(), it violates

    //  the One Definition Rule if used in multiple translation units

    //  where BOOST_DISABLE_ASSERTS, BOOST_ENABLE_ASSERT_HANDLER

    //  NDEBUG are defined inconsistently.

    //  Contributed by Boris Rasin

    namespace detail

    {

        template <typename Target, typename Source>

        struct dynamic_pointer_cast_result

        {

#ifdef BOOST_NO_CXX11_DECLTYPE

            BOOST_TYPEOF_NESTED_TYPEDEF_TPL(nested, dynamic_pointer_cast<Target>(boost::declval<Source>()))

            typedef typename nested::type type;

#else

            typedef decltype(dynamic_pointer_cast<Target>(boost::declval<Source>())) type;

#endif

        };

    }

    template <typename Target, typename Source>

    inline typename detail::dynamic_pointer_cast_result<Target, Source>::type

    polymorphic_pointer_downcast (const Source& x)

    {

        BOOST_ASSERT(dynamic_pointer_cast<Target> (x) == x);

        return static_pointer_cast<Target> (x);

    }

    template <typename Target, typename Source>

    inline typename detail::dynamic_pointer_cast_result<Target, Source>::type

    polymorphic_pointer_cast (const Source& x)

    {

        typename detail::dynamic_pointer_cast_result<Target, Source>::type tmp

            = dynamic_pointer_cast<Target> (x);

        if ( !tmp ) boost::throw_exception( std::bad_cast() );

        return tmp;

    }

} // namespace boost

#endif  // BOOST_CONVERSION_POLYMORPHIC_POINTER_CAST_HPP