boost/type_erasure/dynamic_any_cast.hpp
// Boost.TypeErasure library
//
// Copyright 2015 Steven Watanabe
//
// 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)
//
// $Id$
#ifndef BOOST_TYPE_ERASURE_DYNAMIC_ANY_CAST_HPP_INCLUDED
#define BOOST_TYPE_ERASURE_DYNAMIC_ANY_CAST_HPP_INCLUDED
#include <boost/type_erasure/detail/normalize.hpp>
#include <boost/type_erasure/binding_of.hpp>
#include <boost/type_erasure/static_binding.hpp>
#include <boost/type_erasure/dynamic_binding.hpp>
#include <boost/type_erasure/concept_of.hpp>
#include <boost/type_erasure/placeholder_of.hpp>
#include <boost/type_erasure/any.hpp>
#include <boost/type_erasure/binding.hpp>
#include <boost/mpl/vector.hpp>
#include <boost/mpl/set.hpp>
#include <boost/mpl/fold.hpp>
#include <boost/type_traits/add_const.hpp>
#include <boost/type_traits/add_reference.hpp>
#include <boost/type_traits/remove_const.hpp>
#include <boost/type_traits/remove_reference.hpp>
namespace boost {
namespace type_erasure {
namespace detail {
template<class P, class P2, class Any>
struct make_ref_placeholder;
template<class P, class P2, class Any>
struct make_ref_placeholder<P, P2, const Any&> { typedef const P& type; };
template<class P, class P2, class Any>
struct make_ref_placeholder<P, P2, Any&> { typedef P& type; };
template<class P, class P2, class Any>
struct make_ref_placeholder<P, P2&, const Any&> { typedef P& type; };
template<class P, class P2, class Any>
struct make_ref_placeholder<P, P2&, Any&> { typedef P& type; };
template<class P, class P2, class Any>
struct make_ref_placeholder<P, const P2&, const Any&> { typedef const P& type; };
template<class P, class P2, class Any>
struct make_ref_placeholder<P, const P2&, Any&> { typedef const P& type; };
#ifndef BOOST_NO_CXX11_RVALUE_REFERENCES
template<class P, class P2, class Any>
struct make_ref_placeholder { typedef P&& type; };
template<class P, class P2, class Any>
struct make_ref_placeholder<P, P2&, Any> { typedef P& type; };
template<class P, class P2, class Any>
struct make_ref_placeholder<P, const P2&, Any> { typedef const P& type; };
template<class P, class P2, class Any>
struct make_ref_placeholder<P, P2&&, Any> { typedef P&& type; };
template<class P, class P2, class Any>
struct make_ref_placeholder<P, P2&&, const Any&> { typedef const P& type; };
template<class P, class P2, class Any>
struct make_ref_placeholder<P, P2&&, Any&> { typedef P& type; };
#endif
template<class R, class Tag>
struct make_result_placeholder_map
{
typedef ::boost::mpl::map<
::boost::mpl::pair<
typename ::boost::remove_const<
typename ::boost::remove_reference<
typename ::boost::type_erasure::placeholder_of<R>::type
>::type
>::type,
typename ::boost::remove_const<
typename ::boost::remove_reference<
Tag
>::type
>::type
>
> type;
};
#ifndef BOOST_NO_CXX11_RVALUE_REFERENCES
template<class R, class Any, class Map>
R dynamic_any_cast_impl(Any&& arg, const static_binding<Map>& map)
#else
template<class R, class Any, class Map>
R dynamic_any_cast_impl(Any& arg, const static_binding<Map>& map)
#endif
{
typedef typename ::boost::remove_const<typename ::boost::remove_reference<Any>::type>::type src_type;
typedef typename ::boost::type_erasure::detail::normalize_concept<
typename ::boost::type_erasure::concept_of<src_type>::type
>::type normalized;
typedef typename ::boost::mpl::fold<
normalized,
::boost::mpl::set0<>,
::boost::type_erasure::detail::get_placeholders<
::boost::mpl::_2,
::boost::mpl::_1
>
>::type placeholders;
typedef ::boost::type_erasure::detail::substitution_map< ::boost::mpl::map0<> > identity_map;
::boost::type_erasure::dynamic_binding<placeholders> my_binding(
::boost::type_erasure::binding_of(arg),
::boost::type_erasure::make_binding<identity_map>());
typedef typename ::boost::remove_const<
typename ::boost::remove_reference<
typename ::boost::type_erasure::placeholder_of<R>::type
>::type
>::type result_placeholder;
::boost::type_erasure::binding< typename ::boost::type_erasure::concept_of<R>::type> new_binding(
my_binding,
map);
typedef ::boost::type_erasure::any<
typename ::boost::type_erasure::concept_of<R>::type,
typename ::boost::type_erasure::detail::make_ref_placeholder<
result_placeholder,
typename ::boost::type_erasure::placeholder_of<src_type>::type,
#ifndef BOOST_NO_CXX11_RVALUE_REFERENCES
Any
#else
Any&
#endif
>::type
> result_ref_type;
#ifndef BOOST_NO_CXX11_RVALUE_REFERENCES
return result_ref_type(std::forward<Any>(arg), new_binding);
#else
return result_ref_type(arg, new_binding);
#endif
}
}
#ifdef BOOST_TYPE_ERASURE_DOXYGEN
/**
* Downcasts or crosscasts an @ref any.
*
* \pre @c R and @c Any must both be specializations of @ref any.
* \pre PlaceholderMap must be an MPL map with a key
* for every non-deduced placeholder used by R.
* The value associated with each key should
* be the corresponding placeholder in Any.
* \pre The concept of Any must include @ref typeid_, for every
* @ref placeholder which is used by R.
*
* The single argument form can only be used when @c R uses
* a single non-deduced placeholder.
*
* \throws bad_any_cast if the concepts used by R were
* not previously registered via a call to
* @ref register_binding.
*
* Example:
* \code
* // Assume that typeid_<>, copy_constructible<>, and incrementable<>
* // have all been registered for int.
* any<mpl::vector<typeid_<>, copy_constructible<> > > x(1);
* typedef any<
* mpl::vector<
* typeid_<>,
* copy_constructible<>,
* incrementable<>
* >
* > incrementable_any;
* auto y = dynamic_any_cast<incrementable_any>(x);
* ++y;
* assert(any_cast<int>(y) == 2);
* \endcode
*/
template<class R, class Any>
R dynamic_any_cast(Any&& arg);
/**
* \overload
*/
template<class R, class Any, class Map>
R dynamic_any_cast(Any&& arg, const static_binding<Map>&);
#else
template<class R, class Concept, class Tag>
R dynamic_any_cast(const any<Concept, Tag>& arg)
{
return ::boost::type_erasure::detail::dynamic_any_cast_impl<R>(arg,
::boost::type_erasure::make_binding<typename ::boost::type_erasure::detail::make_result_placeholder_map<R, Tag>::type>());
}
template<class R, class Concept, class Tag>
R dynamic_any_cast(any<Concept, Tag>& arg)
{
return ::boost::type_erasure::detail::dynamic_any_cast_impl<R>(arg,
::boost::type_erasure::make_binding<typename ::boost::type_erasure::detail::make_result_placeholder_map<R, Tag>::type>());
}
#ifndef BOOST_NO_CXX11_RVALUE_REFERENCES
template<class R, class Concept, class Tag>
R dynamic_any_cast(any<Concept, Tag>&& arg)
{
return ::boost::type_erasure::detail::dynamic_any_cast_impl<R>(::std::move(arg),
::boost::type_erasure::make_binding<typename ::boost::type_erasure::detail::make_result_placeholder_map<R, Tag>::type>());
}
#endif
template<class R, class Concept, class Tag, class Map>
R dynamic_any_cast(const any<Concept, Tag>& arg, const static_binding<Map>& map)
{
return ::boost::type_erasure::detail::dynamic_any_cast_impl<R>(arg, map);
}
template<class R, class Concept, class Tag, class Map>
R dynamic_any_cast(any<Concept, Tag>& arg, const static_binding<Map>& map)
{
return ::boost::type_erasure::detail::dynamic_any_cast_impl<R>(arg, map);
}
#ifndef BOOST_NO_CXX11_RVALUE_REFERENCES
template<class R, class Concept, class Tag, class Map>
R dynamic_any_cast(any<Concept, Tag>&& arg, const static_binding<Map>& map)
{
return ::boost::type_erasure::detail::dynamic_any_cast_impl<R>(::std::move(arg), map);
}
#endif
#endif
}
}
#endif