sl@0: // Copyright David Abrahams 2002.
sl@0: // Distributed under the Boost Software License, Version 1.0. (See
sl@0: // accompanying file LICENSE_1_0.txt or copy at
sl@0: // http://www.boost.org/LICENSE_1_0.txt)
sl@0: #ifndef INHERITANCE_DWA200216_HPP
sl@0: # define INHERITANCE_DWA200216_HPP
sl@0: 
sl@0: # include <boost/python/type_id.hpp>
sl@0: # include <boost/shared_ptr.hpp>
sl@0: # include <boost/mpl/if.hpp>
sl@0: # include <boost/type_traits/is_polymorphic.hpp>
sl@0: # include <boost/type_traits/is_base_and_derived.hpp>
sl@0: # include <boost/detail/workaround.hpp>
sl@0: 
sl@0: namespace boost { namespace python { namespace objects {
sl@0: 
sl@0: typedef type_info class_id;
sl@0: using python::type_id;
sl@0: 
sl@0: // Types used to get address and id of most derived type
sl@0: typedef std::pair<void*,class_id> dynamic_id_t;
sl@0: typedef dynamic_id_t (*dynamic_id_function)(void*);
sl@0: 
sl@0: BOOST_PYTHON_DECL void register_dynamic_id_aux(
sl@0:     class_id static_id, dynamic_id_function get_dynamic_id);
sl@0: 
sl@0: BOOST_PYTHON_DECL void add_cast(
sl@0:     class_id src_t, class_id dst_t, void* (*cast)(void*), bool is_downcast);
sl@0: 
sl@0: //
sl@0: // a generator with an execute() function which, given a source type
sl@0: // and a pointer to an object of that type, returns its most-derived
sl@0: // /reachable/ type identifier and object pointer.
sl@0: //
sl@0: 
sl@0: // first, the case where T has virtual functions
sl@0: template <class T>
sl@0: struct polymorphic_id_generator
sl@0: {
sl@0:     static dynamic_id_t execute(void* p_)
sl@0:     {
sl@0:         T* p = static_cast<T*>(p_);
sl@0:         return std::make_pair(dynamic_cast<void*>(p), class_id(typeid(*p)));
sl@0:     }
sl@0: };
sl@0: 
sl@0: // now, the non-polymorphic case.
sl@0: template <class T>
sl@0: struct non_polymorphic_id_generator
sl@0: {
sl@0:     static dynamic_id_t execute(void* p_)
sl@0:     {
sl@0:         return std::make_pair(p_, python::type_id<T>());
sl@0:     }
sl@0: };
sl@0: 
sl@0: // Now the generalized selector
sl@0: template <class T>
sl@0: struct dynamic_id_generator
sl@0:   : mpl::if_<
sl@0:         boost::is_polymorphic<T>
sl@0:         , boost::python::objects::polymorphic_id_generator<T>
sl@0:         , boost::python::objects::non_polymorphic_id_generator<T>
sl@0:     >
sl@0: {};
sl@0: 
sl@0: // Register the dynamic id function for T with the type-conversion
sl@0: // system.
sl@0: template <class T>
sl@0: void register_dynamic_id(T* = 0)
sl@0: {
sl@0:     typedef typename dynamic_id_generator<T>::type generator;
sl@0:     register_dynamic_id_aux(
sl@0:         python::type_id<T>(), &generator::execute);
sl@0: }
sl@0: 
sl@0: //
sl@0: // a generator with an execute() function which, given a void*
sl@0: // pointing to an object of type Source will attempt to convert it to
sl@0: // an object of type Target.
sl@0: //
sl@0: 
sl@0: template <class Source, class Target>
sl@0: struct dynamic_cast_generator
sl@0: {
sl@0:     static void* execute(void* source)
sl@0:     {
sl@0:         return dynamic_cast<Target*>(
sl@0:             static_cast<Source*>(source));
sl@0:     }
sl@0:         
sl@0: };
sl@0: 
sl@0: template <class Source, class Target>
sl@0: struct implicit_cast_generator
sl@0: {
sl@0:     static void* execute(void* source)
sl@0:     {
sl@0:         Target* result = static_cast<Source*>(source);
sl@0:         return result;
sl@0:     }
sl@0: };
sl@0: 
sl@0: template <class Source, class Target>
sl@0: struct cast_generator
sl@0:   : mpl::if_<
sl@0:         is_base_and_derived<Target,Source>
sl@0:       , implicit_cast_generator<Source,Target>
sl@0:       , dynamic_cast_generator<Source,Target>
sl@0:     >
sl@0: {
sl@0: };
sl@0: 
sl@0: template <class Source, class Target>
sl@0: inline void register_conversion(
sl@0:     bool is_downcast = ::boost::is_base_and_derived<Source,Target>::value
sl@0:     // These parameters shouldn't be used; they're an MSVC bug workaround
sl@0:     , Source* = 0, Target* = 0)
sl@0: {
sl@0:     typedef typename cast_generator<Source,Target>::type generator;
sl@0: 
sl@0:     add_cast(
sl@0:         python::type_id<Source>()
sl@0:       , python::type_id<Target>()
sl@0:       , &generator::execute
sl@0:       , is_downcast
sl@0:     );
sl@0: }
sl@0: 
sl@0: }}} // namespace boost::python::object
sl@0: 
sl@0: #endif // INHERITANCE_DWA200216_HPP