Chris@16: /*==============================================================================
Chris@16:     Copyright (c) 2001-2010 Joel de Guzman
Chris@16:     Copyright (c) 2010 Thomas Heller
Chris@16: 
Chris@16:     Distributed under the Boost Software License, Version 1.0. (See accompanying
Chris@16:     file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
Chris@16: ==============================================================================*/
Chris@16: #ifndef BOOST_PHOENIX_CORE_VALUE_HPP
Chris@16: #define BOOST_PHOENIX_CORE_VALUE_HPP
Chris@16: 
Chris@16: #include <boost/phoenix/core/limits.hpp>
Chris@16: #include <boost/phoenix/core/actor.hpp>
Chris@16: #include <boost/phoenix/core/as_actor.hpp>
Chris@16: #include <boost/phoenix/core/terminal.hpp>
Chris@101: #include <boost/phoenix/core/is_value.hpp>
Chris@16: #include <boost/utility/result_of.hpp>
Chris@16: 
Chris@16: namespace boost { namespace phoenix
Chris@16: {
Chris@16:     ////////////////////////////////////////////////////////////////////////////
Chris@16:     //
Chris@16:     // values
Chris@16:     //
Chris@16:     //      function for evaluating values, e.g. val(123)
Chris@16:     //
Chris@16:     ////////////////////////////////////////////////////////////////////////////
Chris@16:  
Chris@16:     namespace expression
Chris@16:     {
Chris@16:         template <typename T>
Chris@16:         struct value
Chris@16:             : expression::terminal<T>
Chris@101:         {
Chris@101:             typedef
Chris@101:                 typename expression::terminal<T>::type
Chris@101:                 type;
Chris@101:            /*
Chris@101:             static const type make(T & t)
Chris@101:             {
Chris@101:                 typename value<T>::type const e = {{t}};
Chris@101:                 return e;
Chris@101:             }
Chris@101:            */
Chris@101:         };
Chris@16:     }
Chris@16: 
Chris@16:     template <typename T>
Chris@101:     inline
Chris@16:     typename expression::value<T>::type const
Chris@101:     val(T t)
Chris@16:     {
Chris@16:         return expression::value<T>::make(t);
Chris@16:     }
Chris@16: 
Chris@101:     // Identifies this Expr as a value.
Chris@101:     // I think this is wrong. It is identifying all actors as values.
Chris@101:     // Yes, it is giving false positives and needs a rethink.
Chris@101:     // And this gives no positives.
Chris@101:     //template <typename T>
Chris@101:     //struct is_value<expression::value<T> >
Chris@101:     //    : mpl::true_
Chris@101:     //{};
Chris@101: 
Chris@16:     // Call out actor for special handling
Chris@101:   // Is this correct? It applies to any actor.
Chris@101:   // In which case why is it here?
Chris@16:     template<typename Expr>
Chris@16:     struct is_custom_terminal<actor<Expr> >
Chris@16:       : mpl::true_
Chris@16:     {};
Chris@16:     
Chris@16:     // Special handling for actor
Chris@16:     template<typename Expr>
Chris@16:     struct custom_terminal<actor<Expr> >
Chris@16:     {
Chris@16:         template <typename Sig>
Chris@16:         struct result;
Chris@16: 
Chris@16:         template <typename This, typename Actor, typename Context>
Chris@16:         struct result<This(Actor, Context)>
Chris@16:             : boost::remove_const<
Chris@101:                     typename boost::remove_reference<
Chris@16:                     typename evaluator::impl<Actor, Context, proto::empty_env>::result_type
Chris@101:                  >::type
Chris@101:              >
Chris@101:         {};
Chris@16: 
Chris@16:         template <typename Context>
Chris@16:         typename result<custom_terminal(actor<Expr> const &, Context &)>::type
Chris@16:         operator()(actor<Expr> const & expr, Context & ctx) const
Chris@16:         {
Chris@101:           typedef typename result<custom_terminal(actor<Expr> const &, Context &)>::type result_type;
Chris@101:           result_type r = boost::phoenix::eval(expr, ctx);
Chris@101:           // std::cout << "Evaluating val() = " << r << std::endl;
Chris@101:           return r;
Chris@16:         }
Chris@16:     };
Chris@16: 
Chris@16:     namespace meta
Chris@16:     {
Chris@16:         template<typename T>
Chris@16:         struct const_ref
Chris@16:             : add_reference<typename add_const<T>::type>
Chris@16:         {};
Chris@16: 
Chris@16:         template<typename T>
Chris@16:         struct argument_type
Chris@16:             : mpl::eval_if_c<
Chris@16:                 is_function<typename remove_pointer<T>::type>::value
Chris@16:               , mpl::identity<T>
Chris@16:               , const_ref<T>
Chris@16:             >
Chris@16:         {
Chris@16:             typedef T type;
Chris@16:         };
Chris@16: 
Chris@16:         template <typename T>
Chris@16:         struct decay
Chris@16:         {
Chris@16:             typedef T type;
Chris@16:         };
Chris@16:         template <typename T, int N>
Chris@16:         struct decay<T[N]> : decay<T const *> {};
Chris@16:     }
Chris@16:     
Chris@16:     template <typename T>
Chris@16:     struct as_actor<T, mpl::false_>
Chris@16:     {
Chris@16:         typedef typename expression::value<typename meta::decay<T>::type >::type type;
Chris@16: 
Chris@16:         static type
Chris@16:         convert(typename meta::argument_type<typename meta::decay<T>::type>::type t)
Chris@16:         {
Chris@16:             return expression::value<typename meta::decay<T>::type >::make(t);
Chris@16:         }
Chris@16:     };
Chris@16: }}
Chris@16: 
Chris@16: #endif