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+// boost polymorphic_pointer_cast.hpp header file ----------------------------------------------//
+// (C) Copyright Boris Rasin and Antony Polukhin 2014-2015.
+// 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)
+
+// See http://www.boost.org/libs/conversion for Documentation.
+
+#ifndef BOOST_CONVERSION_POLYMORPHIC_POINTER_CAST_HPP
+#define BOOST_CONVERSION_POLYMORPHIC_POINTER_CAST_HPP
+
+# include <boost/config.hpp>
+# include <boost/assert.hpp>
+# include <boost/pointer_cast.hpp>
+# include <boost/throw_exception.hpp>
+# include <boost/utility/declval.hpp>
+# ifdef BOOST_NO_CXX11_DECLTYPE
+# include <boost/typeof/typeof.hpp>
+# endif
+
+#ifdef BOOST_HAS_PRAGMA_ONCE
+# pragma once
+#endif
+
+namespace boost
+{
+// See the documentation for descriptions of how to choose between
+// static_pointer_cast<>, dynamic_pointer_cast<>, polymorphic_pointer_cast<> and polymorphic_pointer_downcast<>
+
+// polymorphic_pointer_downcast --------------------------------------------//
+
+ // BOOST_ASSERT() checked polymorphic downcast. Crosscasts prohibited.
+ // Supports any type with static_pointer_cast/dynamic_pointer_cast functions:
+ // built-in pointers, std::shared_ptr, boost::shared_ptr, boost::intrusive_ptr, etc.
+
+ // WARNING: Because this cast uses BOOST_ASSERT(), it violates
+ // the One Definition Rule if used in multiple translation units
+ // where BOOST_DISABLE_ASSERTS, BOOST_ENABLE_ASSERT_HANDLER
+ // NDEBUG are defined inconsistently.
+
+ // Contributed by Boris Rasin
+
+ namespace detail
+ {
+ template <typename Target, typename Source>
+ struct dynamic_pointer_cast_result
+ {
+#ifdef BOOST_NO_CXX11_DECLTYPE
+ BOOST_TYPEOF_NESTED_TYPEDEF_TPL(nested, dynamic_pointer_cast<Target>(boost::declval<Source>()))
+ typedef typename nested::type type;
+#else
+ typedef decltype(dynamic_pointer_cast<Target>(boost::declval<Source>())) type;
+#endif
+ };
+ }
+
+ template <typename Target, typename Source>
+ inline typename detail::dynamic_pointer_cast_result<Target, Source>::type
+ polymorphic_pointer_downcast (const Source& x)
+ {
+ BOOST_ASSERT(dynamic_pointer_cast<Target> (x) == x);
+ return static_pointer_cast<Target> (x);
+ }
+
+ template <typename Target, typename Source>
+ inline typename detail::dynamic_pointer_cast_result<Target, Source>::type
+ polymorphic_pointer_cast (const Source& x)
+ {
+ typename detail::dynamic_pointer_cast_result<Target, Source>::type tmp
+ = dynamic_pointer_cast<Target> (x);
+ if ( !tmp ) boost::throw_exception( std::bad_cast() );
+
+ return tmp;
+ }
+
+} // namespace boost
+
+#endif // BOOST_CONVERSION_POLYMORPHIC_POINTER_CAST_HPP