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