| // Boost.TypeErasure library |
| // |
| // Copyright 2011 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_ANY_CAST_HPP_INCLUDED |
| #define BOOST_TYPE_ERASURE_ANY_CAST_HPP_INCLUDED |
| |
| #include <stdexcept> |
| #include <boost/throw_exception.hpp> |
| #include <boost/type_traits/add_const.hpp> |
| #include <boost/type_traits/is_pointer.hpp> |
| #include <boost/type_traits/remove_cv.hpp> |
| #include <boost/type_traits/remove_reference.hpp> |
| #include <boost/type_traits/remove_pointer.hpp> |
| #include <boost/type_traits/is_void.hpp> |
| #include <boost/mpl/assert.hpp> |
| #include <boost/mpl/bool.hpp> |
| #include <boost/type_erasure/any.hpp> |
| #include <boost/type_erasure/builtin.hpp> |
| #include <boost/type_erasure/exception.hpp> |
| #include <boost/type_erasure/detail/access.hpp> |
| |
| namespace boost { |
| namespace type_erasure { |
| |
| namespace detail { |
| |
| template<class Concept, class T> |
| void* get_pointer(::boost::type_erasure::any<Concept, T>& arg) |
| { |
| return ::boost::type_erasure::detail::access::data(arg).data; |
| } |
| |
| template<class Concept, class T> |
| const void* get_pointer(const ::boost::type_erasure::any<Concept, T>& arg) |
| { |
| return ::boost::type_erasure::detail::access::data(arg).data; |
| } |
| |
| template<class Concept, class T> |
| void* get_pointer(::boost::type_erasure::any<Concept, T&>& arg) |
| { |
| return ::boost::type_erasure::detail::access::data(arg).data; |
| } |
| |
| template<class Concept, class T> |
| void* get_pointer(const ::boost::type_erasure::any<Concept, T&>& arg) |
| { |
| return ::boost::type_erasure::detail::access::data(arg).data; |
| } |
| |
| template<class Concept, class T> |
| const void* get_pointer(::boost::type_erasure::any<Concept, const T&>& arg) |
| { |
| return ::boost::type_erasure::detail::access::data(arg).data; |
| } |
| |
| template<class Concept, class T> |
| const void* get_pointer(const ::boost::type_erasure::any<Concept, const T&>& arg) |
| { |
| return ::boost::type_erasure::detail::access::data(arg).data; |
| } |
| |
| template<class T, class Concept, class Tag> |
| bool check_any_cast(const any<Concept, Tag>&, ::boost::mpl::true_) |
| { |
| return true; |
| } |
| |
| template<class T, class Concept, class Tag> |
| bool check_any_cast(const any<Concept, Tag>& arg, ::boost::mpl::false_) |
| { |
| typedef typename ::boost::remove_cv< |
| typename ::boost::remove_reference<Tag>::type |
| >::type tag_type; |
| return ::boost::type_erasure::detail::access::table(arg) |
| .template find<typeid_<tag_type> >()() == typeid(T); |
| } |
| |
| template<class T, class Concept, class Tag> |
| bool check_any_cast(const any<Concept, Tag>& arg) |
| { |
| return ::boost::type_erasure::detail::check_any_cast<T>( |
| arg, ::boost::is_void<typename ::boost::remove_reference<T>::type>()); |
| } |
| |
| } |
| |
| /** |
| * Attempts to extract the object that @c arg holds. |
| * If casting to a pointer fails, \any_cast returns |
| * a null pointer. Casting to @c void* always succeeds |
| * and returns the address of stored object. |
| * |
| * \code |
| * any<mpl::vector<typeid_<>, copy_constructible<> > > x(1); |
| * any_cast<int>(x); // returns 1 |
| * any_cast<int&>(x); // returns a reference to the contents of x |
| * any_cast<double>(x); // throws bad_any_cast |
| * any_cast<int*>(&x); // returns a pointer to the contents of x |
| * any_cast<void*>(&x); // returns a pointer to the contents of x |
| * any_cast<double*>(&x); // returns NULL |
| * \endcode |
| * |
| * \pre if @c arg is a pointer, @c T must be a pointer type. |
| * \pre @c Concept must contain @ref typeid_<tt><Tag></tt>. |
| * |
| * \throws bad_any_cast if @c arg doesn't contain |
| * an object of type @c T and we're casting |
| * to a value or reference. |
| */ |
| template<class T, class Concept, class Tag> |
| T any_cast(any<Concept, Tag>& arg) |
| { |
| if(::boost::type_erasure::detail::check_any_cast<T>(arg)) { |
| return *static_cast< |
| typename ::boost::remove_reference< |
| typename ::boost::add_const<T>::type |
| >::type* |
| >(::boost::type_erasure::detail::get_pointer(arg)); |
| } else { |
| BOOST_THROW_EXCEPTION(::boost::type_erasure::bad_any_cast()); |
| } |
| } |
| |
| /** \overload */ |
| template<class T, class Concept, class Tag> |
| T any_cast(const any<Concept, Tag>& arg) |
| { |
| if(::boost::type_erasure::detail::check_any_cast<T>(arg)) { |
| return *static_cast< |
| typename ::boost::remove_reference< |
| typename ::boost::add_const<T>::type |
| >::type* |
| >(::boost::type_erasure::detail::get_pointer(arg)); |
| } else { |
| BOOST_THROW_EXCEPTION(::boost::type_erasure::bad_any_cast()); |
| } |
| } |
| |
| /** \overload */ |
| template<class T, class Concept, class Tag> |
| T any_cast(any<Concept, Tag>* arg) |
| { |
| BOOST_MPL_ASSERT((::boost::is_pointer<T>)); |
| if(::boost::type_erasure::detail::check_any_cast< |
| typename ::boost::remove_pointer<T>::type>(*arg)) { |
| return static_cast< |
| typename ::boost::remove_pointer<T>::type*>( |
| ::boost::type_erasure::detail::get_pointer(*arg)); |
| } else { |
| return 0; |
| } |
| } |
| |
| /** \overload */ |
| template<class T, class Concept, class Tag> |
| T any_cast(const any<Concept, Tag>* arg) |
| { |
| BOOST_MPL_ASSERT((::boost::is_pointer<T>)); |
| if(::boost::type_erasure::detail::check_any_cast< |
| typename ::boost::remove_pointer<T>::type>(*arg)) { |
| return static_cast< |
| typename ::boost::remove_pointer<T>::type*>( |
| ::boost::type_erasure::detail::get_pointer(*arg)); |
| } else { |
| return 0; |
| } |
| } |
| |
| } |
| } |
| |
| #endif |