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Copy pathinheritance.hpp
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131 lines (111 loc) · 3.46 KB
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// Copyright David Abrahams 2002.
// 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)
#ifndef INHERITANCE_DWA200216_HPP
# define INHERITANCE_DWA200216_HPP
# include <boost/python/type_id.hpp>
# include <boost/shared_ptr.hpp>
# include <boost/mpl/if.hpp>
# include <boost/detail/workaround.hpp>
# include <boost/python/detail/type_traits.hpp>
namespace boost { namespace python { namespace objects {
typedef type_info class_id;
using python::type_id;
// Types used to get address and id of most derived type
typedef std::pair<void*,class_id> dynamic_id_t;
typedef dynamic_id_t (*dynamic_id_function)(void*);
BOOST_PYTHON_DECL void register_dynamic_id_aux(
class_id static_id, dynamic_id_function get_dynamic_id);
BOOST_PYTHON_DECL void add_cast(
class_id src_t, class_id dst_t, void* (*cast)(void*), bool is_downcast);
//
// a generator with an execute() function which, given a source type
// and a pointer to an object of that type, returns its most-derived
// /reachable/ type identifier and object pointer.
//
// first, the case where T has virtual functions
template <class T>
struct polymorphic_id_generator
{
static dynamic_id_t execute(void* p_)
{
T* p = static_cast<T*>(p_);
return std::make_pair(dynamic_cast<void*>(p), class_id(typeid(*p)));
}
};
// now, the non-polymorphic case.
template <class T>
struct non_polymorphic_id_generator
{
static dynamic_id_t execute(void* p_)
{
return std::make_pair(p_, python::type_id<T>());
}
};
// Now the generalized selector
template <class T>
struct dynamic_id_generator
: mpl::if_<
boost::python::detail::is_polymorphic<T>
, boost::python::objects::polymorphic_id_generator<T>
, boost::python::objects::non_polymorphic_id_generator<T>
>
{};
// Register the dynamic id function for T with the type-conversion
// system.
template <class T>
void register_dynamic_id(T* = 0)
{
typedef typename dynamic_id_generator<T>::type generator;
register_dynamic_id_aux(
python::type_id<T>(), &generator::execute);
}
//
// a generator with an execute() function which, given a void*
// pointing to an object of type Source will attempt to convert it to
// an object of type Target.
//
template <class Source, class Target>
struct dynamic_cast_generator
{
static void* execute(void* source)
{
return dynamic_cast<Target*>(
static_cast<Source*>(source));
}
};
template <class Source, class Target>
struct implicit_cast_generator
{
static void* execute(void* source)
{
Target* result = static_cast<Source*>(source);
return result;
}
};
template <class Source, class Target>
struct cast_generator
: mpl::if_<
boost::python::detail::is_base_and_derived<Target,Source>
, implicit_cast_generator<Source,Target>
, dynamic_cast_generator<Source,Target>
>
{
};
template <class Source, class Target>
inline void register_conversion(
bool is_downcast = ::boost::is_base_and_derived<Source,Target>::value
// These parameters shouldn't be used; they're an MSVC bug workaround
, Source* = 0, Target* = 0)
{
typedef typename cast_generator<Source,Target>::type generator;
add_cast(
python::type_id<Source>()
, python::type_id<Target>()
, &generator::execute
, is_downcast
);
}
}}} // namespace boost::python::object
#endif // INHERITANCE_DWA200216_HPP