171 lines
5.0 KiB
C++
171 lines
5.0 KiB
C++
// Boost.TypeErasure library
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//
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// Copyright 2011 Steven Watanabe
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//
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// Distributed under the Boost Software License Version 1.0. (See
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// accompanying file LICENSE_1_0.txt or copy at
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// http://www.boost.org/LICENSE_1_0.txt)
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//
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// $Id: any_cast.hpp 80974 2012-10-13 00:02:25Z steven_watanabe $
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#ifndef BOOST_TYPE_ERASURE_ANY_CAST_HPP_INCLUDED
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#define BOOST_TYPE_ERASURE_ANY_CAST_HPP_INCLUDED
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#include <stdexcept>
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#include <boost/throw_exception.hpp>
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#include <boost/type_traits/add_const.hpp>
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#include <boost/type_traits/is_pointer.hpp>
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#include <boost/type_traits/remove_cv.hpp>
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#include <boost/type_traits/remove_reference.hpp>
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#include <boost/type_traits/remove_pointer.hpp>
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#include <boost/type_traits/is_void.hpp>
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#include <boost/mpl/assert.hpp>
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#include <boost/mpl/bool.hpp>
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#include <boost/type_erasure/any.hpp>
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#include <boost/type_erasure/builtin.hpp>
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#include <boost/type_erasure/exception.hpp>
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#include <boost/type_erasure/detail/access.hpp>
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namespace boost {
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namespace type_erasure {
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namespace detail {
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template<class Concept, class T>
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void* get_pointer(::boost::type_erasure::any<Concept, T>& arg)
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{
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return ::boost::type_erasure::detail::access::data(arg).data;
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}
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template<class Concept, class T>
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const void* get_pointer(const ::boost::type_erasure::any<Concept, T>& arg)
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{
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return ::boost::type_erasure::detail::access::data(arg).data;
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}
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template<class Concept, class T>
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void* get_pointer(::boost::type_erasure::any<Concept, T&>& arg)
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{
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return ::boost::type_erasure::detail::access::data(arg).data;
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}
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template<class Concept, class T>
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void* get_pointer(const ::boost::type_erasure::any<Concept, T&>& arg)
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{
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return ::boost::type_erasure::detail::access::data(arg).data;
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}
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template<class Concept, class T>
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const void* get_pointer(::boost::type_erasure::any<Concept, const T&>& arg)
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{
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return ::boost::type_erasure::detail::access::data(arg).data;
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}
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template<class Concept, class T>
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const void* get_pointer(const ::boost::type_erasure::any<Concept, const T&>& arg)
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{
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return ::boost::type_erasure::detail::access::data(arg).data;
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}
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template<class T, class Concept, class Tag>
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bool check_any_cast(const any<Concept, Tag>&, ::boost::mpl::true_)
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{
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return true;
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}
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template<class T, class Concept, class Tag>
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bool check_any_cast(const any<Concept, Tag>& arg, ::boost::mpl::false_)
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{
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typedef typename ::boost::remove_cv<
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typename ::boost::remove_reference<Tag>::type
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>::type tag_type;
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return ::boost::type_erasure::detail::access::table(arg)
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.template find<typeid_<tag_type> >()() == typeid(T);
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}
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template<class T, class Concept, class Tag>
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bool check_any_cast(const any<Concept, Tag>& arg)
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{
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return ::boost::type_erasure::detail::check_any_cast<T>(
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arg, ::boost::is_void<typename ::boost::remove_reference<T>::type>());
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}
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}
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/**
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* Attempts to extract the object that @c arg holds.
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* If casting to a pointer fails, \any_cast returns
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* a null pointer. Casting to @c void* always succeeds
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* and returns the address of stored object.
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*
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* \pre if @c arg is a pointer, @c T must be a pointer type.
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* \pre @c Concept must contain @ref typeid_<tt><Tag></tt>.
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*
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* \throws bad_any_cast if @c arg doesn't contain
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* an object of type @c T and we're casting
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* to a value or reference.
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*/
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template<class T, class Concept, class Tag>
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T any_cast(any<Concept, Tag>& arg)
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{
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if(::boost::type_erasure::detail::check_any_cast<T>(arg)) {
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return *static_cast<
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typename ::boost::remove_reference<
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typename ::boost::add_const<T>::type
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>::type*
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>(::boost::type_erasure::detail::get_pointer(arg));
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} else {
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BOOST_THROW_EXCEPTION(::boost::type_erasure::bad_any_cast());
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}
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}
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/** \overload */
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template<class T, class Concept, class Tag>
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T any_cast(const any<Concept, Tag>& arg)
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{
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if(::boost::type_erasure::detail::check_any_cast<T>(arg)) {
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return *static_cast<
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typename ::boost::remove_reference<
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typename ::boost::add_const<T>::type
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>::type*
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>(::boost::type_erasure::detail::get_pointer(arg));
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} else {
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BOOST_THROW_EXCEPTION(::boost::type_erasure::bad_any_cast());
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}
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}
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/** \overload */
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template<class T, class Concept, class Tag>
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T any_cast(any<Concept, Tag>* arg)
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{
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BOOST_MPL_ASSERT((::boost::is_pointer<T>));
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if(::boost::type_erasure::detail::check_any_cast<
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typename ::boost::remove_pointer<T>::type>(*arg)) {
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return static_cast<
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typename ::boost::remove_pointer<T>::type*>(
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::boost::type_erasure::detail::get_pointer(*arg));
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} else {
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return 0;
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}
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}
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/** \overload */
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template<class T, class Concept, class Tag>
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T any_cast(const any<Concept, Tag>* arg)
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{
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BOOST_MPL_ASSERT((::boost::is_pointer<T>));
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if(::boost::type_erasure::detail::check_any_cast<
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typename ::boost::remove_pointer<T>::type>(*arg)) {
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return static_cast<
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typename ::boost::remove_pointer<T>::type*>(
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::boost::type_erasure::detail::get_pointer(*arg));
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} else {
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return 0;
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}
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}
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}
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}
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#endif
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