Chris@16: /*==============================================================================
Chris@16:     Copyright (c) 2001-2010 Joel de Guzman
Chris@16:     Copyright (c) 2004 Daniel Wallin
Chris@16:     Copyright (c) 2010 Thomas Heller
Chris@101:     Copyright (c) 2015 John Fletcher
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_SCOPE_LET_HPP
Chris@16: #define BOOST_PHOENIX_SCOPE_LET_HPP
Chris@16: 
Chris@101: //#include <boost/assert.hpp>
Chris@101: //#include <sstream>
Chris@16: #include <boost/phoenix/core/limits.hpp>
Chris@16: #include <boost/fusion/include/transform.hpp>
Chris@16: #include <boost/fusion/include/as_vector.hpp>
Chris@16: #include <boost/phoenix/core/call.hpp>
Chris@16: #include <boost/phoenix/core/expression.hpp>
Chris@16: #include <boost/phoenix/core/meta_grammar.hpp>
Chris@16: #include <boost/phoenix/scope/scoped_environment.hpp>
Chris@16: #include <boost/phoenix/scope/local_variable.hpp>
Chris@16: #include <boost/phoenix/support/iterate.hpp>
Chris@16: #include <boost/phoenix/support/vector.hpp>
Chris@16: 
Chris@16: BOOST_PHOENIX_DEFINE_EXPRESSION(
Chris@16:     (boost)(phoenix)(let_)
Chris@16:   , (proto::terminal<proto::_>) // Locals
Chris@16:     (proto::terminal<proto::_>) // Map
Chris@16:     (meta_grammar)
Chris@16: )
Chris@16: 
Chris@16: namespace boost { namespace phoenix
Chris@16: {
Chris@16:     struct let_eval
Chris@16:     {
Chris@16:           template <typename Sig>
Chris@16:           struct result;
Chris@16: 
Chris@16:           template <typename This, typename Vars, typename Map, typename Expr, typename Context>
Chris@16:           struct result<This(Vars, Map, Expr, Context)>
Chris@16:           {
Chris@16:             typedef
Chris@16:                 typename proto::detail::uncvref<
Chris@16:                     typename result_of::env<Context>::type
Chris@16:                 >::type
Chris@16:                 env_type;
Chris@16:             typedef
Chris@16:                 typename proto::detail::uncvref<
Chris@16:                     typename result_of::actions<Context>::type
Chris@16:                 >::type
Chris@16:                 actions_type;
Chris@16:             typedef
Chris@16:                 typename proto::detail::uncvref<
Chris@16:                     typename proto::result_of::value<Vars>::type
Chris@16:                      >::type
Chris@16:                      vars_type;
Chris@16:             typedef
Chris@16:                 typename proto::detail::uncvref<
Chris@16:                     typename proto::result_of::value<Map>::type
Chris@16:                      >::type
Chris@16:                      map_type;
Chris@101: 
Chris@101:             typedef
Chris@101:                 typename proto::detail::uncvref<Expr>::type
Chris@101:                      expr_type;
Chris@16:             
Chris@101:             typedef typename
Chris@16:                 detail::result_of::initialize_locals<
Chris@16:                     vars_type
Chris@16:                   , Context
Chris@16:                 >::type
Chris@16:             locals_type;
Chris@16: 
Chris@16:             typedef typename
Chris@16:                 result_of::eval<
Chris@101:                     expr_type
Chris@16:                   , typename result_of::context<
Chris@16:                         scoped_environment<
Chris@16:                             env_type
Chris@16:                           , env_type
Chris@16:                           , locals_type
Chris@16:                           , map_type
Chris@16:                         >
Chris@16:                       , actions_type
Chris@16:                     >::type
Chris@16:                 >::type
Chris@16:                 type;
Chris@16:           };
Chris@16: 
Chris@16:         template <typename Vars, typename Map, typename Expr, typename Context>
Chris@16:         typename result<let_eval(Vars const&, Map const&, Expr const &, Context const &)>::type const
Chris@16:         operator()(Vars const & vars, Map, Expr const & expr, Context const & ctx) const
Chris@16:         {
Chris@101:             Vars vars_(vars);
Chris@101: 
Chris@16:             typedef
Chris@16:                 typename proto::detail::uncvref<
Chris@16:                     typename result_of::env<Context>::type
Chris@16:                 >::type
Chris@16:                 env_type;
Chris@16:             typedef
Chris@16:                 typename proto::detail::uncvref<
Chris@16:                     typename proto::result_of::value<Vars>::type
Chris@16:                 >::type
Chris@16:                 vars_type;
Chris@16:             typedef
Chris@16:                 typename proto::detail::uncvref<
Chris@16:                     typename proto::result_of::value<Map>::type
Chris@16:                 >::type
Chris@16:                 map_type;
Chris@16:             
Chris@16:             typedef typename 
Chris@16:                 detail::result_of::initialize_locals<
Chris@16:                     vars_type
Chris@16:                   , Context
Chris@16:                 >::type
Chris@16:             locals_type;
Chris@16: 
Chris@101:             locals_type locals = initialize_locals(proto::value(vars_), ctx);
Chris@101: 
Chris@101:             typedef typename result<let_eval(Vars const&, Map const&, Expr const &, Context const &)>::type result_type;
Chris@16: 
Chris@16:             scoped_environment<
Chris@16:                 env_type
Chris@16:               , env_type
Chris@16:               , locals_type
Chris@16:               , map_type
Chris@16:             >
Chris@16:             env(phoenix::env(ctx), phoenix::env(ctx), locals);
Chris@16: 
Chris@101:             // Fix for bugs (trial)
Chris@101:             // The idea is to do something which will not be optimised away.
Chris@101:             //int vsize = boost::fusion::size(vars);
Chris@101:             //std::stringstream strm;
Chris@101:             //strm << vsize << std::endl;
Chris@101:             //int size = strm.str().length();
Chris@101:             //BOOST_ASSERT(size >= 0);
Chris@101:             result_type r = eval(expr, phoenix::context(env, phoenix::actions(ctx)));
Chris@101:             // typedef is_value<result_type> is_val;
Chris@101:             //if(is_val::value) This seems always to be true
Chris@101:             //{
Chris@101:             //   std::cout << "let result has value type" << std::endl;
Chris@101:             // }
Chris@101:             //if (is_val(r) ) std::cout << "let returns val" << std::endl;
Chris@101:             //std::cout << "result is " << r << std::endl;
Chris@101:             return r;
Chris@16:         }
Chris@16:     };
Chris@16: 
Chris@16:     template <typename Dummy>
Chris@16:     struct default_actions::when<rule::let_, Dummy>
Chris@16:         : call<let_eval, Dummy>
Chris@16:     {};
Chris@16: 
Chris@16:     template <typename Locals, typename Map>
Chris@16:     struct let_actor_gen
Chris@16:     {
Chris@101:         let_actor_gen(Locals const & locals_)
Chris@101:             : locals(locals_)
Chris@16:         {}
Chris@16: 
Chris@16:         let_actor_gen(let_actor_gen const & o)
Chris@16:             : locals(o.locals)
Chris@16:         {}
Chris@16: 
Chris@16:         template <typename Expr>
Chris@16:         typename expression::let_<
Chris@16:             Locals
Chris@16:           , Map
Chris@16:           , Expr
Chris@16:         >::type const
Chris@16:         operator[](Expr const & expr) const
Chris@16:         {
Chris@101:            typedef typename expression::let_<
Chris@101:               Locals
Chris@101:             , Map
Chris@101:             , Expr
Chris@101:            >::type let_type;
Chris@101:            //typedef is_value<let_type> is_val;
Chris@101: 
Chris@101:            let_type let_exp = expression::let_<Locals, Map, Expr>::make(locals, Map(), expr);
Chris@101:            //if(is_val::value) //This seems always to be true
Chris@101:            //{
Chris@101:            //  std::cout << "let has value type" << std::endl;
Chris@101:            //}
Chris@101:            return let_exp;
Chris@16:         }
Chris@16: 
Chris@16:         Locals locals;
Chris@16:     };
Chris@16: 
Chris@16: #define BOOST_PHOENIX_SCOPE_ACTOR_GEN_NAME let_actor_gen
Chris@16: #define BOOST_PHOENIX_SCOPE_ACTOR_GEN_FUNCTION let
Chris@16: #define BOOST_PHOENIX_SCOPE_ACTOR_GEN_CONST
Chris@16:     #include <boost/phoenix/scope/detail/local_gen.hpp>
Chris@16: #undef BOOST_PHOENIX_SCOPE_ACTOR_GEN_NAME
Chris@16: #undef BOOST_PHOENIX_SCOPE_ACTOR_GEN_FUNCTION
Chris@16: #undef BOOST_PHOENIX_SCOPE_ACTOR_GEN_CONST
Chris@16: 
Chris@16:     template <typename Dummy>
Chris@16:     struct is_nullary::when<rule::let_, Dummy>
Chris@16:         : proto::make<
Chris@16:             mpl::and_<
Chris@16:                 proto::fold<
Chris@16:                     proto::call<proto::_value(proto::_child_c<0>)>
Chris@16:                   , proto::make<mpl::true_()>
Chris@16:                   , proto::make<
Chris@16:                         mpl::and_<
Chris@16:                             proto::_state
Chris@16:                           , proto::call<
Chris@16:                                 evaluator(
Chris@16:                                     proto::_
Chris@16:                                   , _context
Chris@16:                                   , proto::make<proto::empty_env()>
Chris@16:                                 )
Chris@16:                             >
Chris@16:                         >()
Chris@16:                     >
Chris@16:                 >
Chris@16:               , evaluator(
Chris@16:                     proto::_child_c<2>
Chris@16:                   , proto::call<
Chris@16:                         functional::context(
Chris@16:                             proto::make<
Chris@16:                                 mpl::true_()
Chris@16:                             >
Chris@16:                           , proto::make<
Chris@16:                                 detail::scope_is_nullary_actions()
Chris@16:                             >
Chris@16:                         )
Chris@16:                     >
Chris@16:                   , proto::make<
Chris@16:                         proto::empty_env()
Chris@16:                     >
Chris@16:                 )
Chris@16:             >()
Chris@16:         >
Chris@16:     {};
Chris@16: }}
Chris@16: 
Chris@16: #endif