Chris@102: //  boost polymorphic_pointer_cast.hpp header file  ----------------------------------------------//
Chris@102: //  (C) Copyright Boris Rasin and Antony Polukhin 2014-2015.
Chris@102: //  Distributed under the Boost
Chris@102: //  Software License, Version 1.0. (See accompanying file
Chris@102: //  LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
Chris@102: 
Chris@102: //  See http://www.boost.org/libs/conversion for Documentation.
Chris@102: 
Chris@102: #ifndef BOOST_CONVERSION_POLYMORPHIC_POINTER_CAST_HPP
Chris@102: #define BOOST_CONVERSION_POLYMORPHIC_POINTER_CAST_HPP
Chris@102: 
Chris@102: # include <boost/config.hpp>
Chris@102: # include <boost/assert.hpp>
Chris@102: # include <boost/pointer_cast.hpp>
Chris@102: # include <boost/throw_exception.hpp>
Chris@102: # include <boost/utility/declval.hpp>
Chris@102: # ifdef BOOST_NO_CXX11_DECLTYPE
Chris@102: #   include <boost/typeof/typeof.hpp>
Chris@102: # endif
Chris@102: 
Chris@102: #ifdef BOOST_HAS_PRAGMA_ONCE
Chris@102: #   pragma once
Chris@102: #endif
Chris@102: 
Chris@102: namespace boost
Chris@102: {
Chris@102: //  See the documentation for descriptions of how to choose between
Chris@102: //  static_pointer_cast<>, dynamic_pointer_cast<>, polymorphic_pointer_cast<> and polymorphic_pointer_downcast<>
Chris@102: 
Chris@102: //  polymorphic_pointer_downcast  --------------------------------------------//
Chris@102: 
Chris@102:     //  BOOST_ASSERT() checked polymorphic downcast.  Crosscasts prohibited.
Chris@102:     //  Supports any type with static_pointer_cast/dynamic_pointer_cast functions:
Chris@102:     //  built-in pointers, std::shared_ptr, boost::shared_ptr, boost::intrusive_ptr, etc.
Chris@102: 
Chris@102:     //  WARNING: Because this cast uses BOOST_ASSERT(), it violates
Chris@102:     //  the One Definition Rule if used in multiple translation units
Chris@102:     //  where BOOST_DISABLE_ASSERTS, BOOST_ENABLE_ASSERT_HANDLER
Chris@102:     //  NDEBUG are defined inconsistently.
Chris@102: 
Chris@102:     //  Contributed by Boris Rasin
Chris@102: 
Chris@102:     namespace detail
Chris@102:     {
Chris@102:         template <typename Target, typename Source>
Chris@102:         struct dynamic_pointer_cast_result
Chris@102:         {
Chris@102: #ifdef BOOST_NO_CXX11_DECLTYPE
Chris@102:             BOOST_TYPEOF_NESTED_TYPEDEF_TPL(nested, dynamic_pointer_cast<Target>(boost::declval<Source>()))
Chris@102:             typedef typename nested::type type;
Chris@102: #else
Chris@102:             typedef decltype(dynamic_pointer_cast<Target>(boost::declval<Source>())) type;
Chris@102: #endif
Chris@102:         };
Chris@102:     }
Chris@102: 
Chris@102:     template <typename Target, typename Source>
Chris@102:     inline typename detail::dynamic_pointer_cast_result<Target, Source>::type
Chris@102:     polymorphic_pointer_downcast (const Source& x)
Chris@102:     {
Chris@102:         BOOST_ASSERT(dynamic_pointer_cast<Target> (x) == x);
Chris@102:         return static_pointer_cast<Target> (x);
Chris@102:     }
Chris@102: 
Chris@102:     template <typename Target, typename Source>
Chris@102:     inline typename detail::dynamic_pointer_cast_result<Target, Source>::type
Chris@102:     polymorphic_pointer_cast (const Source& x)
Chris@102:     {
Chris@102:         typename detail::dynamic_pointer_cast_result<Target, Source>::type tmp
Chris@102:             = dynamic_pointer_cast<Target> (x);
Chris@102:         if ( !tmp ) boost::throw_exception( std::bad_cast() );
Chris@102: 
Chris@102:         return tmp;
Chris@102:     }
Chris@102: 
Chris@102: } // namespace boost
Chris@102: 
Chris@102: #endif  // BOOST_CONVERSION_POLYMORPHIC_POINTER_CAST_HPP