Chris@16: /*=============================================================================
Chris@16:     Copyright (c) 2001-2007 Joel de Guzman
Chris@16:     Copyright (c) 2004 Daniel Wallin
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_SCOPE_LET_HPP
Chris@16: #define PHOENIX_SCOPE_LET_HPP
Chris@16: 
Chris@16: #include <boost/spirit/home/phoenix/core/limits.hpp>
Chris@16: #include <boost/spirit/home/phoenix/core/composite.hpp>
Chris@16: #include <boost/spirit/home/phoenix/scope/scoped_environment.hpp>
Chris@16: #include <boost/spirit/home/phoenix/scope/detail/local_variable.hpp>
Chris@16: #include <boost/spirit/home/phoenix/detail/local_reference.hpp>
Chris@16: #include <boost/spirit/home/phoenix/core/actor.hpp>
Chris@16: #include <boost/fusion/include/transform.hpp>
Chris@16: #include <boost/fusion/include/as_vector.hpp>
Chris@16: #include <boost/mpl/eval_if.hpp>
Chris@16: #include <boost/mpl/bool.hpp>
Chris@16: 
Chris@16: namespace boost { namespace phoenix
Chris@16: {
Chris@16:     template <typename Base, typename Vars, typename Map>
Chris@16:     struct let_actor : Base
Chris@16:     {
Chris@16:         typedef typename
Chris@16:             mpl::fold<
Chris@16:                 Vars
Chris@16:               , mpl::false_
Chris@16:               , detail::compute_no_nullary
Chris@16:             >::type
Chris@16:         no_nullary;
Chris@16:         
Chris@16:         template <typename Env>
Chris@16:         struct result
Chris@16:         {
Chris@16:             typedef typename 
Chris@16:                 fusion::result_of::as_vector<
Chris@16:                     typename fusion::result_of::transform<
Chris@16:                         Vars
Chris@16:                       , detail::initialize_local<Env>
Chris@16:                     >::type
Chris@16:                 >::type 
Chris@16:             locals_type;
Chris@16: 
Chris@16:             typedef typename Base::template
Chris@16:                 result<scoped_environment<Env, Env, locals_type, Map> >::type
Chris@16:             result_type;
Chris@16:             
Chris@16:             typedef typename 
Chris@16:                 detail::unwrap_local_reference<result_type>::type 
Chris@16:             type;
Chris@16:         };
Chris@16: 
Chris@16:         let_actor(Base const& base, Vars const& vars)
Chris@16:             : Base(base), vars(vars) {}
Chris@16: 
Chris@16:         template <typename Env>
Chris@16:         typename result<Env>::type
Chris@16:         eval(Env const& env) const
Chris@16:         {
Chris@16:             typedef typename 
Chris@16:                 fusion::result_of::as_vector<
Chris@16:                     typename fusion::result_of::transform<
Chris@16:                         Vars
Chris@16:                       , detail::initialize_local<Env>
Chris@16:                     >::type
Chris@16:                 >::type 
Chris@16:             locals_type;
Chris@16: 
Chris@16:             locals_type locals = 
Chris@16:                 fusion::as_vector(
Chris@16:                     fusion::transform(
Chris@16:                         vars
Chris@16:                       , detail::initialize_local<Env>(env)));
Chris@16:             
Chris@16:             typedef typename result<Env>::type RT;
Chris@16:             return RT(Base::eval(
Chris@16:                 scoped_environment<Env, Env, locals_type, Map>(
Chris@16:                     env
Chris@16:                   , env
Chris@16:                   , locals)));
Chris@16:         }
Chris@16: 
Chris@16:         Vars vars;
Chris@16:     };
Chris@16:     
Chris@16:     template <typename Vars, typename Map>
Chris@16:     struct let_actor_gen
Chris@16:     {
Chris@16:         template <typename Base>
Chris@16:         actor<let_actor<Base, Vars, Map> > const
Chris@16:         operator[](actor<Base> const& base) const
Chris@16:         {
Chris@16:             return let_actor<Base, Vars, Map>(base, vars);
Chris@16:         }
Chris@16: 
Chris@16:         let_actor_gen(Vars const& vars)
Chris@16:             : vars(vars) {}
Chris@16: 
Chris@16:         Vars vars;
Chris@16:     };
Chris@16: 
Chris@16:     template <typename Key>
Chris@16:     struct local_variable; // forward
Chris@16:     struct assign_eval; // forward
Chris@16: 
Chris@16:     struct let_gen
Chris@16:     {
Chris@16:         template <typename K0, typename V0>
Chris@16:         let_actor_gen<
Chris@16:             fusion::vector<V0>
Chris@16:           , detail::map_local_index_to_tuple<K0>
Chris@16:         >
Chris@16:         operator()(
Chris@16:             actor<composite<assign_eval, fusion::vector<local_variable<K0>, V0> > > const& a0
Chris@16:         ) const
Chris@16:         {
Chris@16:             return fusion::vector<V0>(fusion::at_c<1>(a0));
Chris@16:         }
Chris@16:     
Chris@16:         template <typename K0, typename K1, typename V0, typename V1>
Chris@16:         let_actor_gen<
Chris@16:             fusion::vector<V0, V1>
Chris@16:           , detail::map_local_index_to_tuple<K0, K1>
Chris@16:         >
Chris@16:         operator()(
Chris@16:             actor<composite<assign_eval, fusion::vector<local_variable<K0>, V0> > > const& a0
Chris@16:           , actor<composite<assign_eval, fusion::vector<local_variable<K1>, V1> > > const& a1
Chris@16:         ) const
Chris@16:         {
Chris@16:             return fusion::vector<V0, V1>(fusion::at_c<1>(a0), fusion::at_c<1>(a1));
Chris@16:         }
Chris@16:         
Chris@16:         // Bring in the rest...
Chris@16:         #define PHOENIX_LOCAL_GEN_NAME let_actor_gen
Chris@16:         #include <boost/spirit/home/phoenix/scope/detail/local_gen.hpp>
Chris@16:         #undef PHOENIX_LOCAL_GEN_NAME
Chris@16:     };
Chris@16: 
Chris@16:     let_gen const let = let_gen();
Chris@16: }}
Chris@16: 
Chris@16: #endif