phoenix/object/dynamic_cast.hpp

0001 /*==============================================================================
0002     Copyright (c) 2001-2010 Joel de Guzman
0003     Copyright (c) 2010 Thomas Heller
0004
0005     Distributed under the Boost Software License, Version 1.0. (See accompanying
0006     file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
0007 ==============================================================================*/
0008 #ifndef BOOST_PHOENIX_OBJECT_DYNAMIC_CAST_HPP
0009 #define BOOST_PHOENIX_OBJECT_DYNAMIC_CAST_HPP
0010
0011 #include <boost/phoenix/core/limits.hpp>
0012 #include <boost/phoenix/core/call.hpp>
0013 #include <boost/phoenix/core/expression.hpp>
0014 #include <boost/phoenix/core/meta_grammar.hpp>
0015 #include <boost/phoenix/object/detail/target.hpp>
0016 #include <boost/proto/transform/lazy.hpp>
0017
0018 BOOST_PHOENIX_DEFINE_EXPRESSION(
0019     (boost)(phoenix)(dynamic_cast_)
0020   , (proto::terminal<detail::target<proto::_> >)
0021     (meta_grammar)
0022 )
0023
0024 namespace boost { namespace phoenix
0025 {
0026     struct dynamic_cast_eval
0027     {
0028         template <typename Sig>
0029         struct result;
0030
0031         template <typename This, typename Target, typename Source, typename Context>
0032         struct result<This(Target, Source, Context)>
0033             : detail::result_of::target<Target>
0034         {};
0035
0036         template <typename Target, typename Source, typename Context>
0037         typename detail::result_of::target<Target>::type
0038         operator()(Target, Source const& u, Context const& ctx) const
0039         {
0040             return
0041                 dynamic_cast<
0042                     typename detail::result_of::target<Target>::type
0043                 >(boost::phoenix::eval(u, ctx));
0044         }
0045     };
0046
0047     template <typename Dummy>
0048     struct default_actions::when<rule::dynamic_cast_, Dummy>
0049         : call<dynamic_cast_eval, Dummy>
0050     {};
0051
0052     template <typename T, typename U>
0053     inline
0054     typename expression::dynamic_cast_<detail::target<T>, U>::type const
0055     dynamic_cast_(U const& u)
0056     {
0057         return
0058             expression::
0059                 dynamic_cast_<detail::target<T>, U>::
0060                     make(detail::target<T>(), u);
0061     }
0062 }}
0063
0064 #endif