Chris@16: // Copyright David Abrahams 2002.
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: #ifndef INHERITANCE_DWA200216_HPP
Chris@16: # define INHERITANCE_DWA200216_HPP
Chris@16: 
Chris@16: # include <boost/python/type_id.hpp>
Chris@16: # include <boost/shared_ptr.hpp>
Chris@16: # include <boost/mpl/if.hpp>
Chris@16: # include <boost/type_traits/is_polymorphic.hpp>
Chris@16: # include <boost/type_traits/is_base_and_derived.hpp>
Chris@16: # include <boost/detail/workaround.hpp>
Chris@16: 
Chris@16: namespace boost { namespace python { namespace objects {
Chris@16: 
Chris@16: typedef type_info class_id;
Chris@16: using python::type_id;
Chris@16: 
Chris@16: // Types used to get address and id of most derived type
Chris@16: typedef std::pair<void*,class_id> dynamic_id_t;
Chris@16: typedef dynamic_id_t (*dynamic_id_function)(void*);
Chris@16: 
Chris@16: BOOST_PYTHON_DECL void register_dynamic_id_aux(
Chris@16:     class_id static_id, dynamic_id_function get_dynamic_id);
Chris@16: 
Chris@16: BOOST_PYTHON_DECL void add_cast(
Chris@16:     class_id src_t, class_id dst_t, void* (*cast)(void*), bool is_downcast);
Chris@16: 
Chris@16: //
Chris@16: // a generator with an execute() function which, given a source type
Chris@16: // and a pointer to an object of that type, returns its most-derived
Chris@16: // /reachable/ type identifier and object pointer.
Chris@16: //
Chris@16: 
Chris@16: // first, the case where T has virtual functions
Chris@16: template <class T>
Chris@16: struct polymorphic_id_generator
Chris@16: {
Chris@16:     static dynamic_id_t execute(void* p_)
Chris@16:     {
Chris@16:         T* p = static_cast<T*>(p_);
Chris@16:         return std::make_pair(dynamic_cast<void*>(p), class_id(typeid(*p)));
Chris@16:     }
Chris@16: };
Chris@16: 
Chris@16: // now, the non-polymorphic case.
Chris@16: template <class T>
Chris@16: struct non_polymorphic_id_generator
Chris@16: {
Chris@16:     static dynamic_id_t execute(void* p_)
Chris@16:     {
Chris@16:         return std::make_pair(p_, python::type_id<T>());
Chris@16:     }
Chris@16: };
Chris@16: 
Chris@16: // Now the generalized selector
Chris@16: template <class T>
Chris@16: struct dynamic_id_generator
Chris@16:   : mpl::if_<
Chris@16:         boost::is_polymorphic<T>
Chris@16:         , boost::python::objects::polymorphic_id_generator<T>
Chris@16:         , boost::python::objects::non_polymorphic_id_generator<T>
Chris@16:     >
Chris@16: {};
Chris@16: 
Chris@16: // Register the dynamic id function for T with the type-conversion
Chris@16: // system.
Chris@16: template <class T>
Chris@16: void register_dynamic_id(T* = 0)
Chris@16: {
Chris@16:     typedef typename dynamic_id_generator<T>::type generator;
Chris@16:     register_dynamic_id_aux(
Chris@16:         python::type_id<T>(), &generator::execute);
Chris@16: }
Chris@16: 
Chris@16: //
Chris@16: // a generator with an execute() function which, given a void*
Chris@16: // pointing to an object of type Source will attempt to convert it to
Chris@16: // an object of type Target.
Chris@16: //
Chris@16: 
Chris@16: template <class Source, class Target>
Chris@16: struct dynamic_cast_generator
Chris@16: {
Chris@16:     static void* execute(void* source)
Chris@16:     {
Chris@16:         return dynamic_cast<Target*>(
Chris@16:             static_cast<Source*>(source));
Chris@16:     }
Chris@16:         
Chris@16: };
Chris@16: 
Chris@16: template <class Source, class Target>
Chris@16: struct implicit_cast_generator
Chris@16: {
Chris@16:     static void* execute(void* source)
Chris@16:     {
Chris@16:         Target* result = static_cast<Source*>(source);
Chris@16:         return result;
Chris@16:     }
Chris@16: };
Chris@16: 
Chris@16: template <class Source, class Target>
Chris@16: struct cast_generator
Chris@16:   : mpl::if_<
Chris@16:         is_base_and_derived<Target,Source>
Chris@16:       , implicit_cast_generator<Source,Target>
Chris@16:       , dynamic_cast_generator<Source,Target>
Chris@16:     >
Chris@16: {
Chris@16: };
Chris@16: 
Chris@16: template <class Source, class Target>
Chris@16: inline void register_conversion(
Chris@16:     bool is_downcast = ::boost::is_base_and_derived<Source,Target>::value
Chris@16:     // These parameters shouldn't be used; they're an MSVC bug workaround
Chris@16:     , Source* = 0, Target* = 0)
Chris@16: {
Chris@16:     typedef typename cast_generator<Source,Target>::type generator;
Chris@16: 
Chris@16:     add_cast(
Chris@16:         python::type_id<Source>()
Chris@16:       , python::type_id<Target>()
Chris@16:       , &generator::execute
Chris@16:       , is_downcast
Chris@16:     );
Chris@16: }
Chris@16: 
Chris@16: }}} // namespace boost::python::object
Chris@16: 
Chris@16: #endif // INHERITANCE_DWA200216_HPP