Chris@16: /*=============================================================================
Chris@16:     Copyright (c) 2001-2007 Joel de Guzman
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 PHOENIX_STATEMENT_IF_HPP
Chris@16: #define PHOENIX_STATEMENT_IF_HPP
Chris@16: 
Chris@16: #include <boost/spirit/home/phoenix/core/composite.hpp>
Chris@16: #include <boost/spirit/home/phoenix/core/as_actor.hpp>
Chris@16: #include <boost/spirit/home/phoenix/core/compose.hpp>
Chris@16: 
Chris@16: #if defined(BOOST_MSVC)
Chris@16: # pragma warning(push)
Chris@16: # pragma warning(disable:4355)
Chris@16: #endif
Chris@16: 
Chris@16: namespace boost { namespace phoenix
Chris@16: {
Chris@16:     struct if_else_eval
Chris@16:     {
Chris@16:         template <typename Env, typename Cond, typename Then, typename Else>
Chris@16:         struct result
Chris@16:         {
Chris@16:             typedef void type;
Chris@16:         };
Chris@16: 
Chris@16:         template <
Chris@16:             typename RT, typename Env
Chris@16:           , typename Cond, typename Then, typename Else>
Chris@16:         static void
Chris@16:         eval(Env const& env, Cond& cond, Then& then, Else& else_)
Chris@16:         {
Chris@16:             if (cond.eval(env))
Chris@16:                 then.eval(env);
Chris@16:             else
Chris@16:                 else_.eval(env);
Chris@16:         }
Chris@16:     };
Chris@16: 
Chris@16:     struct if_eval
Chris@16:     {
Chris@16:         template <typename Env, typename Cond, typename Then>
Chris@16:         struct result
Chris@16:         {
Chris@16:             typedef void type;
Chris@16:         };
Chris@16: 
Chris@16:         template <typename RT, typename Env, typename Cond, typename Then>
Chris@16:         static void
Chris@16:         eval(Env const& env, Cond& cond, Then& then)
Chris@16:         {
Chris@16:             if (cond.eval(env))
Chris@16:                 then.eval(env);
Chris@16:         }
Chris@16:     };
Chris@16: 
Chris@16:     template <typename Cond, typename Then>
Chris@16:     struct if_composite;
Chris@16: 
Chris@16:     template <typename Cond, typename Then>
Chris@16:     struct else_gen
Chris@16:     {
Chris@16:         else_gen(if_composite<Cond, Then> const& source)
Chris@16:             : source(source) {}
Chris@16: 
Chris@16:         template <typename Else>
Chris@16:         actor<typename as_composite<if_else_eval, Cond, Then, Else>::type>
Chris@16:         operator[](Else const& else_) const
Chris@16:         {
Chris@16:             return compose<if_else_eval>(
Chris@16:                 fusion::at_c<0>(source) // cond
Chris@16:               , fusion::at_c<1>(source) // then
Chris@16:               , else_ // else
Chris@16:             );
Chris@16:         }
Chris@16: 
Chris@16:         if_composite<Cond, Then> const& source;
Chris@16: 
Chris@16:     private:
Chris@16:         // silence MSVC warning C4512: assignment operator could not be generated
Chris@16:         else_gen& operator= (else_gen const&);
Chris@16:     };
Chris@16: 
Chris@16:     template <typename Cond, typename Then>
Chris@16:     struct if_composite : composite<if_eval, fusion::vector<Cond, Then> >
Chris@16:     {
Chris@16:         if_composite(Cond const& cond, Then const& then)
Chris@16:             : composite<if_eval, fusion::vector<Cond, Then> >(cond, then)
Chris@16:             , else_(*this) {}
Chris@16: 
Chris@16:         else_gen<Cond, Then> else_;
Chris@16: 
Chris@16:     private:
Chris@16:         // silence MSVC warning C4512: assignment operator could not be generated
Chris@16:         if_composite& operator= (if_composite const&);
Chris@16:     };
Chris@16: 
Chris@16:     template <typename Cond>
Chris@16:     struct if_gen
Chris@16:     {
Chris@16:         if_gen(Cond const& cond)
Chris@16:             : cond(cond) {}
Chris@16: 
Chris@16:         template <typename Then>
Chris@16:         actor<if_composite<Cond, typename as_actor<Then>::type> >
Chris@16:         operator[](Then const& then) const
Chris@16:         {
Chris@16:             return actor<if_composite<Cond, typename as_actor<Then>::type> >(
Chris@16:                 cond, as_actor<Then>::convert(then));
Chris@16:         }
Chris@16: 
Chris@16:         Cond cond;
Chris@16:     };
Chris@16: 
Chris@16:     template <typename Cond>
Chris@16:     inline if_gen<typename as_actor<Cond>::type>
Chris@16:     if_(Cond const& cond)
Chris@16:     {
Chris@16:         return if_gen<typename as_actor<Cond>::type>(
Chris@16:             as_actor<Cond>::convert(cond));
Chris@16:     }
Chris@16: }}
Chris@16: 
Chris@16: #if defined(BOOST_MSVC)
Chris@16: # pragma warning(pop)
Chris@16: #endif
Chris@16: 
Chris@16: #endif