| /*============================================================================= |
| Copyright (c) 2001-2007 Joel de Guzman |
| Copyright (c) 2004 Daniel Wallin |
| |
| Distributed under the Boost Software License, Version 1.0. (See accompanying |
| file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) |
| ==============================================================================*/ |
| #ifndef PHOENIX_SCOPE_LET_HPP |
| #define PHOENIX_SCOPE_LET_HPP |
| |
| #include <boost/spirit/home/phoenix/core/limits.hpp> |
| #include <boost/spirit/home/phoenix/core/composite.hpp> |
| #include <boost/spirit/home/phoenix/scope/scoped_environment.hpp> |
| #include <boost/spirit/home/phoenix/scope/detail/local_variable.hpp> |
| #include <boost/spirit/home/phoenix/detail/local_reference.hpp> |
| #include <boost/spirit/home/phoenix/core/actor.hpp> |
| #include <boost/fusion/include/transform.hpp> |
| #include <boost/fusion/include/as_vector.hpp> |
| #include <boost/mpl/eval_if.hpp> |
| #include <boost/mpl/bool.hpp> |
| |
| namespace boost { namespace phoenix |
| { |
| template <typename Base, typename Vars, typename Map> |
| struct let_actor : Base |
| { |
| typedef typename |
| mpl::fold< |
| Vars |
| , mpl::false_ |
| , detail::compute_no_nullary |
| >::type |
| no_nullary; |
| |
| template <typename Env> |
| struct result |
| { |
| typedef typename |
| fusion::result_of::as_vector< |
| typename fusion::result_of::transform< |
| Vars |
| , detail::initialize_local<Env> |
| >::type |
| >::type |
| locals_type; |
| |
| typedef typename Base::template |
| result<scoped_environment<Env, Env, locals_type, Map> >::type |
| result_type; |
| |
| typedef typename |
| detail::unwrap_local_reference<result_type>::type |
| type; |
| }; |
| |
| let_actor(Base const& base, Vars const& vars) |
| : Base(base), vars(vars) {} |
| |
| template <typename Env> |
| typename result<Env>::type |
| eval(Env const& env) const |
| { |
| typedef typename |
| fusion::result_of::as_vector< |
| typename fusion::result_of::transform< |
| Vars |
| , detail::initialize_local<Env> |
| >::type |
| >::type |
| locals_type; |
| |
| locals_type locals = |
| fusion::as_vector( |
| fusion::transform( |
| vars |
| , detail::initialize_local<Env>(env))); |
| |
| typedef typename result<Env>::type RT; |
| return RT(Base::eval( |
| scoped_environment<Env, Env, locals_type, Map>( |
| env |
| , env |
| , locals))); |
| } |
| |
| Vars vars; |
| }; |
| |
| template <typename Vars, typename Map> |
| struct let_actor_gen |
| { |
| template <typename Base> |
| actor<let_actor<Base, Vars, Map> > const |
| operator[](actor<Base> const& base) const |
| { |
| return let_actor<Base, Vars, Map>(base, vars); |
| } |
| |
| let_actor_gen(Vars const& vars) |
| : vars(vars) {} |
| |
| Vars vars; |
| }; |
| |
| template <typename Key> |
| struct local_variable; // forward |
| struct assign_eval; // forward |
| |
| struct let_gen |
| { |
| template <typename K0, typename V0> |
| let_actor_gen< |
| fusion::vector<V0> |
| , detail::map_local_index_to_tuple<K0> |
| > |
| operator()( |
| actor<composite<assign_eval, fusion::vector<local_variable<K0>, V0> > > const& a0 |
| ) const |
| { |
| return fusion::vector<V0>(fusion::at_c<1>(a0)); |
| } |
| |
| template <typename K0, typename K1, typename V0, typename V1> |
| let_actor_gen< |
| fusion::vector<V0, V1> |
| , detail::map_local_index_to_tuple<K0, K1> |
| > |
| operator()( |
| actor<composite<assign_eval, fusion::vector<local_variable<K0>, V0> > > const& a0 |
| , actor<composite<assign_eval, fusion::vector<local_variable<K1>, V1> > > const& a1 |
| ) const |
| { |
| return fusion::vector<V0, V1>(fusion::at_c<1>(a0), fusion::at_c<1>(a1)); |
| } |
| |
| // Bring in the rest... |
| #define PHOENIX_LOCAL_GEN_NAME let_actor_gen |
| #include <boost/spirit/home/phoenix/scope/detail/local_gen.hpp> |
| #undef PHOENIX_LOCAL_GEN_NAME |
| }; |
| |
| let_gen const let = let_gen(); |
| }} |
| |
| #endif |