boost/python/object/class_metadata.hpp
// Copyright David Abrahams 2004. // Copyright Stefan Seefeld 2016. // 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 boost_python_object_class_metadata_hpp_ #define boost_python_object_class_metadata_hpp_ #include <boost/python/converter/shared_ptr_from_python.hpp> #include <boost/python/object/inheritance.hpp> #include <boost/python/object/class_wrapper.hpp> #include <boost/python/object/make_instance.hpp> #include <boost/python/object/value_holder.hpp> #include <boost/python/object/pointer_holder.hpp> #include <boost/python/object/make_ptr_instance.hpp> #include <boost/python/detail/force_instantiate.hpp> #include <boost/python/detail/not_specified.hpp> #include <boost/python/detail/type_traits.hpp> #include <boost/python/has_back_reference.hpp> #include <boost/python/bases.hpp> #include <boost/mpl/if.hpp> #include <boost/mpl/eval_if.hpp> #include <boost/mpl/bool.hpp> #include <boost/mpl/or.hpp> #include <boost/mpl/identity.hpp> #include <boost/mpl/for_each.hpp> #include <boost/mpl/placeholders.hpp> #include <boost/mpl/single_view.hpp> #include <boost/mpl/assert.hpp> #include <boost/noncopyable.hpp> #include <boost/detail/workaround.hpp> namespace boost { namespace python { namespace objects { BOOST_PYTHON_DECL void copy_class_object(type_info const& src, type_info const& dst); // // Support for registering base/derived relationships // template <class Derived> struct register_base_of { template <class Base> inline void operator()(Base*) const { BOOST_MPL_ASSERT_NOT((boost::python::detail::is_same<Base,Derived>)); // Register the Base class register_dynamic_id<Base>(); // Register the up-cast register_conversion<Derived,Base>(false); // Register the down-cast, if appropriate. this->register_downcast((Base*)0, boost::python::detail::is_polymorphic<Base>()); } private: static inline void register_downcast(void*, boost::python::detail::false_) {} template <class Base> static inline void register_downcast(Base*, boost::python::detail::true_) { register_conversion<Base, Derived>(true); } }; // // Preamble of register_class. Also used for callback classes, which // need some registration of their own. // template <class T, class Bases> inline void register_shared_ptr_from_python_and_casts(T*, Bases) { // Constructor performs registration python::detail::force_instantiate(converter::shared_ptr_from_python<T, boost::shared_ptr>()); #if !defined(BOOST_NO_CXX11_SMART_PTR) python::detail::force_instantiate(converter::shared_ptr_from_python<T, std::shared_ptr>()); #endif // // register all up/downcasts here. We're using the alternate // interface to mpl::for_each to avoid an MSVC 6 bug. // register_dynamic_id<T>(); mpl::for_each(register_base_of<T>(), (Bases*)0, (boost::python::detail::add_pointer<mpl::_>*)0); } // // Helper for choosing the unnamed held_type argument // template <class T, class Prev> struct select_held_type : mpl::if_< mpl::or_< python::detail::specifies_bases<T> , boost::python::detail::is_same<T,noncopyable> > , Prev , T > { }; template < class T // class being wrapped , class X1 // = detail::not_specified , class X2 // = detail::not_specified , class X3 // = detail::not_specified > struct class_metadata { // // Calculate the unnamed template arguments // // held_type_arg -- not_specified, [a class derived from] T or a // smart pointer to [a class derived from] T. Preserving // not_specified allows us to give class_<T,T> a back-reference. typedef typename select_held_type< X1 , typename select_held_type< X2 , typename select_held_type< X3 , python::detail::not_specified >::type >::type >::type held_type_arg; // bases typedef typename python::detail::select_bases< X1 , typename python::detail::select_bases< X2 , typename python::detail::select_bases< X3 , python::bases<> >::type >::type >::type bases; typedef mpl::or_< boost::python::detail::is_same<X1,noncopyable> , boost::python::detail::is_same<X2,noncopyable> , boost::python::detail::is_same<X3,noncopyable> > is_noncopyable; // // Holder computation. // // Compute the actual type that will be held in the Holder. typedef typename mpl::if_< boost::python::detail::is_same<held_type_arg,python::detail::not_specified>, T, held_type_arg >::type held_type; // Determine if the object will be held by value typedef mpl::bool_<boost::python::detail::is_convertible<held_type*,T*>::value> use_value_holder; // Compute the "wrapped type", that is, if held_type is a smart // pointer, we're talking about the pointee. typedef typename mpl::eval_if< use_value_holder , mpl::identity<held_type> , pointee<held_type> >::type wrapped; // Determine whether to use a "back-reference holder" typedef mpl::bool_< mpl::or_< has_back_reference<T> , boost::python::detail::is_same<held_type_arg,T> , is_base_and_derived<T,wrapped> >::value > use_back_reference; // Select the holder. typedef typename mpl::eval_if< use_back_reference , mpl::if_< use_value_holder , value_holder_back_reference<T, wrapped> , pointer_holder_back_reference<held_type,T> > , mpl::if_< use_value_holder , value_holder<T> , pointer_holder<held_type,wrapped> > >::type holder; inline static void register_() // Register the runtime metadata. { class_metadata::register_aux((T*)0); } private: template <class T2> inline static void register_aux(python::wrapper<T2>*) { typedef typename mpl::not_<boost::python::detail::is_same<T2,wrapped> >::type use_callback; class_metadata::register_aux2((T2*)0, use_callback()); } inline static void register_aux(void*) { typedef typename is_base_and_derived<T,wrapped>::type use_callback; class_metadata::register_aux2((T*)0, use_callback()); } template <class T2, class Callback> inline static void register_aux2(T2*, Callback) { objects::register_shared_ptr_from_python_and_casts((T2*)0, bases()); class_metadata::maybe_register_callback_class((T2*)0, Callback()); class_metadata::maybe_register_class_to_python((T2*)0, is_noncopyable()); class_metadata::maybe_register_pointer_to_python( (T2*)0, (use_value_holder*)0, (use_back_reference*)0); } // // Support for converting smart pointers to python // inline static void maybe_register_pointer_to_python(...) {} #ifndef BOOST_PYTHON_NO_PY_SIGNATURES inline static void maybe_register_pointer_to_python(void*,void*,mpl::true_*) { objects::copy_class_object(python::type_id<T>(), python::type_id<back_reference<T const &> >()); objects::copy_class_object(python::type_id<T>(), python::type_id<back_reference<T &> >()); } #endif template <class T2> inline static void maybe_register_pointer_to_python(T2*, mpl::false_*, mpl::false_*) { python::detail::force_instantiate( objects::class_value_wrapper< held_type , make_ptr_instance<T2, pointer_holder<held_type, T2> > >() ); #ifndef BOOST_PYTHON_NO_PY_SIGNATURES // explicit qualification of type_id makes msvc6 happy objects::copy_class_object(python::type_id<T2>(), python::type_id<held_type>()); #endif } // // Support for registering to-python converters // inline static void maybe_register_class_to_python(void*, mpl::true_) {} template <class T2> inline static void maybe_register_class_to_python(T2*, mpl::false_) { python::detail::force_instantiate(class_cref_wrapper<T2, make_instance<T2, holder> >()); #ifndef BOOST_PYTHON_NO_PY_SIGNATURES // explicit qualification of type_id makes msvc6 happy objects::copy_class_object(python::type_id<T2>(), python::type_id<held_type>()); #endif } // // Support for registering callback classes // inline static void maybe_register_callback_class(void*, mpl::false_) {} template <class T2> inline static void maybe_register_callback_class(T2*, mpl::true_) { objects::register_shared_ptr_from_python_and_casts( (wrapped*)0, mpl::single_view<T2>()); // explicit qualification of type_id makes msvc6 happy objects::copy_class_object(python::type_id<T2>(), python::type_id<wrapped>()); } }; }}} // namespace boost::python::object #endif