Chris@16: ///////////////////////////////////////////////////////////////////////////////
Chris@16: /// \file eval.hpp
Chris@16: /// Contains the eval() expression evaluator.
Chris@16: //
Chris@16: //  Copyright 2008 Eric Niebler. Distributed under the Boost
Chris@16: //  Software License, Version 1.0. (See accompanying file
Chris@16: //  LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
Chris@16: 
Chris@16: #ifndef BOOST_PROTO_EVAL_HPP_EAN_03_29_2007
Chris@16: #define BOOST_PROTO_EVAL_HPP_EAN_03_29_2007
Chris@16: 
Chris@16: #include <boost/proto/proto_fwd.hpp> // BOOST_PROTO_CALLABLE
Chris@16: #include <boost/type_traits/remove_reference.hpp>
Chris@16: 
Chris@16: namespace boost { namespace proto
Chris@16: {
Chris@16: 
Chris@16:     namespace result_of
Chris@16:     {
Chris@16:         /// \brief A metafunction for calculating the return type
Chris@16:         /// of \c proto::eval() given a certain \c Expr and \c Context
Chris@16:         /// types.
Chris@16:         ///
Chris@16:         /// \note The types \c Expr and \c Context should not be
Chris@16:         /// reference types. They may be cv-qualified, but the
Chris@16:         /// cv-qualification on the \c Context parameter is ignored.
Chris@16:         template<typename Expr, typename Context>
Chris@16:         struct eval
Chris@16:         {
Chris@16:             typedef typename Context::template eval<Expr>::result_type type;
Chris@16:         };
Chris@16:     }
Chris@16: 
Chris@16:     namespace functional
Chris@16:     {
Chris@16:         /// \brief A PolymorphicFunctionObject type for
Chris@16:         /// evaluating a given Proto expression with a given
Chris@16:         /// context.
Chris@16:         struct eval
Chris@16:         {
Chris@16:             BOOST_PROTO_CALLABLE()
Chris@16: 
Chris@16:             template<typename Sig>
Chris@16:             struct result;
Chris@16: 
Chris@16:             template<typename This, typename Expr, typename Context>
Chris@16:             struct result<This(Expr, Context)>
Chris@16:             {
Chris@16:                 typedef
Chris@16:                     typename proto::result_of::eval<
Chris@16:                         typename remove_reference<Expr>::type
Chris@16:                       , typename remove_reference<Context>::type
Chris@16:                     >::type
Chris@16:                 type;
Chris@16:             };
Chris@16: 
Chris@16:             /// \brief Evaluate a given Proto expression with a given
Chris@16:             /// context.
Chris@16:             /// \param expr The Proto expression to evaluate
Chris@16:             /// \param context The context in which the expression should be
Chris@16:             ///     evaluated.
Chris@16:             /// \return <tt>typename Context::template eval<Expr>()(expr, context)</tt>
Chris@16:             template<typename Expr, typename Context>
Chris@16:             typename proto::result_of::eval<Expr, Context>::type
Chris@16:             operator ()(Expr &e, Context &ctx) const
Chris@16:             {
Chris@16:                 return typename Context::template eval<Expr>()(e, ctx);
Chris@16:             }
Chris@16: 
Chris@16:             /// \overload
Chris@16:             ///
Chris@16:             template<typename Expr, typename Context>
Chris@16:             typename proto::result_of::eval<Expr, Context>::type
Chris@16:             operator ()(Expr &e, Context const &ctx) const
Chris@16:             {
Chris@16:                 return typename Context::template eval<Expr>()(e, ctx);
Chris@16:             }
Chris@16: 
Chris@16:             /// \overload
Chris@16:             ///
Chris@16:             template<typename Expr, typename Context>
Chris@16:             typename proto::result_of::eval<Expr const, Context>::type
Chris@16:             operator ()(Expr const &e, Context &ctx) const
Chris@16:             {
Chris@16:                 return typename Context::template eval<Expr const>()(e, ctx);
Chris@16:             }
Chris@16: 
Chris@16:             /// \overload
Chris@16:             ///
Chris@16:             template<typename Expr, typename Context>
Chris@16:             typename proto::result_of::eval<Expr const, Context>::type
Chris@16:             operator ()(Expr const &e, Context const &ctx) const
Chris@16:             {
Chris@16:                 return typename Context::template eval<Expr const>()(e, ctx);
Chris@16:             }
Chris@16:         };
Chris@16:     }
Chris@16: 
Chris@16:     /// \brief Evaluate a given Proto expression with a given
Chris@16:     /// context.
Chris@16:     /// \param expr The Proto expression to evaluate
Chris@16:     /// \param context The context in which the expression should be
Chris@16:     ///     evaluated.
Chris@16:     /// \return <tt>typename Context::template eval<Expr>()(expr, context)</tt>
Chris@16:     template<typename Expr, typename Context>
Chris@16:     typename proto::result_of::eval<Expr, Context>::type
Chris@16:     eval(Expr &e, Context &ctx)
Chris@16:     {
Chris@16:         return typename Context::template eval<Expr>()(e, ctx);
Chris@16:     }
Chris@16: 
Chris@16:     /// \overload
Chris@16:     ///
Chris@16:     template<typename Expr, typename Context>
Chris@16:     typename proto::result_of::eval<Expr, Context>::type
Chris@16:     eval(Expr &e, Context const &ctx)
Chris@16:     {
Chris@16:         return typename Context::template eval<Expr>()(e, ctx);
Chris@16:     }
Chris@16: 
Chris@16:     /// \overload
Chris@16:     ///
Chris@16:     template<typename Expr, typename Context>
Chris@16:     typename proto::result_of::eval<Expr const, Context>::type
Chris@16:     eval(Expr const &e, Context &ctx)
Chris@16:     {
Chris@16:         return typename Context::template eval<Expr const>()(e, ctx);
Chris@16:     }
Chris@16: 
Chris@16:     /// \overload
Chris@16:     ///
Chris@16:     template<typename Expr, typename Context>
Chris@16:     typename proto::result_of::eval<Expr const, Context>::type
Chris@16:     eval(Expr const &e, Context const &ctx)
Chris@16:     {
Chris@16:         return typename Context::template eval<Expr const>()(e, ctx);
Chris@16:     }
Chris@16: }}
Chris@16: 
Chris@16: #endif