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- // 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_ "typeid_<Tag>".
- *
- * \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
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