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_DETAIL_SWITCH_HPP
Chris@16: #define PHOENIX_STATEMENT_DETAIL_SWITCH_HPP
Chris@16: 
Chris@16: #include <boost/spirit/home/phoenix/core/nothing.hpp>
Chris@16: #include <boost/fusion/include/vector.hpp>
Chris@16: #include <boost/fusion/include/as_vector.hpp>
Chris@16: #include <boost/fusion/include/push_back.hpp>
Chris@16: #include <boost/fusion/include/push_front.hpp>
Chris@16: #include <boost/fusion/include/begin.hpp>
Chris@16: #include <boost/fusion/include/size.hpp>
Chris@16: #include <boost/fusion/include/value_of.hpp>
Chris@16: #include <boost/fusion/include/is_sequence.hpp>
Chris@16: #include <boost/mpl/identity.hpp>
Chris@16: #include <boost/mpl/bool.hpp>
Chris@16: #include <boost/mpl/eval_if.hpp>
Chris@16: #include <boost/mpl/if.hpp>
Chris@16: 
Chris@16: namespace boost { namespace phoenix
Chris@16: {
Chris@16: 
Chris@16:     template <typename Actor, typename K, K Value>
Chris@16:     struct switch_case;
Chris@16: 
Chris@16:     template <typename Actor>
Chris@16:     struct default_case;
Chris@16: 
Chris@16:     namespace detail
Chris@16:     {
Chris@16:         template <typename T>
Chris@16:         struct is_default_case : mpl::bool_<T::is_default> {};
Chris@16: 
Chris@16:         template <typename A0, typename A1>
Chris@16:         struct compose_case_a
Chris@16:         {
Chris@16:             // here, A0 and A1 are both switch cases
Chris@16:             typedef typename
Chris@16:                 mpl::if_<
Chris@16:                     is_default_case<A1>
Chris@16:                   , fusion::vector<actor<A1>, actor<A0> >
Chris@16:                   , fusion::vector<actor<A0>, actor<A1> >
Chris@16:                 >::type
Chris@16:             type;
Chris@16: 
Chris@16:             static type
Chris@16:             eval(A0 const& _0, A1 const& _1, mpl::false_)
Chris@16:             {
Chris@16:                 return type(_0, _1);
Chris@16:             }
Chris@16: 
Chris@16:             static type
Chris@16:             eval(A0 const& _0, A1 const& _1, mpl::true_)
Chris@16:             {
Chris@16:                 return type(_1, _0);
Chris@16:             }
Chris@16: 
Chris@16:             static type
Chris@16:             eval(A0 const& _0, A1 const& _1)
Chris@16:             {
Chris@16:                 return eval(_0, _1, is_default_case<A1>());
Chris@16:             }
Chris@16:         };
Chris@16: 
Chris@16:         template <typename Seq, typename Case>
Chris@16:         struct compose_case_b
Chris@16:         {
Chris@16:             typedef typename fusion::result_of::as_vector<
Chris@16:                 typename mpl::eval_if<
Chris@16:                     is_default_case<Case>
Chris@16:                   , fusion::result_of::push_front<Seq const, actor<Case> >
Chris@16:                   , fusion::result_of::push_back<Seq const, actor<Case> >
Chris@16:             >::type>::type
Chris@16:             type;
Chris@16: 
Chris@16:             static type
Chris@16:             eval(Seq const& seq, Case const& case_, mpl::false_)
Chris@16:             {
Chris@16:                 return fusion::as_vector(
Chris@16:                     fusion::push_back(seq, actor<Case>(case_)));
Chris@16:             }
Chris@16: 
Chris@16:             static type
Chris@16:             eval(Seq const& seq, Case const& case_, mpl::true_)
Chris@16:             {
Chris@16:                 return fusion::as_vector(
Chris@16:                     fusion::push_front(seq, actor<Case>(case_)));
Chris@16:             }
Chris@16: 
Chris@16:             static type
Chris@16:             eval(Seq const& seq, Case const& case_)
Chris@16:             {
Chris@16:                 return eval(seq, case_, is_default_case<Case>());
Chris@16:             }
Chris@16:         };
Chris@16: 
Chris@16:         template <typename Cases>
Chris@16:         struct ensure_default
Chris@16:         {
Chris@16:             typedef
Chris@16:                 is_default_case<
Chris@16:                     typename fusion::result_of::value_of<
Chris@16:                         typename fusion::result_of::begin<Cases>::type
Chris@16:                     >::type
Chris@16:                 >
Chris@16:             is_default_case_;
Chris@16: 
Chris@16:             typedef typename
Chris@16:                 mpl::eval_if<
Chris@16:                     is_default_case_
Chris@16:                   , mpl::identity<Cases>
Chris@16:                   , fusion::result_of::push_front<
Chris@16:                         Cases const, actor<default_case<actor<null_actor> > > >
Chris@16:                 >::type
Chris@16:             type;
Chris@16: 
Chris@16:             static type
Chris@16:             eval(Cases const& cases, mpl::false_);
Chris@16: 
Chris@16:             static type
Chris@16:             eval(Cases const& cases, mpl::true_)
Chris@16:             {
Chris@16:                 return cases;
Chris@16:             }
Chris@16: 
Chris@16:             static type
Chris@16:             eval(Cases const& cases)
Chris@16:             {
Chris@16:                 return eval(cases, is_default_case_());
Chris@16:             }
Chris@16:         };
Chris@16: 
Chris@16:         template <typename Cond, typename Cases>
Chris@16:         struct switch_composite
Chris@16:         {
Chris@16:             BOOST_STATIC_ASSERT(fusion::traits::is_sequence<Cases>::value);
Chris@16:             typedef ensure_default<Cases> ensure_default_;
Chris@16: 
Chris@16:             typedef typename
Chris@16:                 fusion::result_of::as_vector<
Chris@16:                     typename fusion::result_of::push_front<
Chris@16:                         typename ensure_default_::type, Cond>::type
Chris@16:                     >::type
Chris@16:             tuple_type;
Chris@16: 
Chris@16:             typedef
Chris@16:                 composite<
Chris@16:                     detail::switch_eval<fusion::result_of::size<tuple_type>::value-2>
Chris@16:                   , tuple_type>
Chris@16:             type;
Chris@16: 
Chris@16:             static type
Chris@16:             eval(Cond const& cond, Cases const& cases)
Chris@16:             {
Chris@16:                 return fusion::as_vector(
Chris@16:                     fusion::push_front(ensure_default_::eval(cases), cond));
Chris@16:             }
Chris@16:         };
Chris@16: 
Chris@16:         template <typename Cond, typename Cases>
Chris@16:         struct switch_composite_actor
Chris@16:         {
Chris@16:             typedef actor<typename switch_composite<Cond, Cases>::type> type;
Chris@16:         };
Chris@16:     }
Chris@16: }}
Chris@16: 
Chris@16: #endif