Chris@16: /*=============================================================================
Chris@16:     Copyright (c) 2002-2003 Joel de Guzman
Chris@16:     Copyright (c) 2002-2003 Hartmut Kaiser
Chris@16:     http://spirit.sourceforge.net/
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: #if !defined(BOOST_SPIRIT_TRAVERSE_HPP)
Chris@16: #define BOOST_SPIRIT_TRAVERSE_HPP
Chris@16: 
Chris@16: #include <boost/spirit/home/classic/namespace.hpp>
Chris@16: #include <boost/spirit/home/classic/meta/impl/traverse.ipp>
Chris@16: 
Chris@16: namespace boost { namespace spirit {
Chris@16: 
Chris@16: BOOST_SPIRIT_CLASSIC_NAMESPACE_BEGIN
Chris@16: 
Chris@16:     ///////////////////////////////////////////////////////////////////////////
Chris@16:     //
Chris@16:     //  Post-order traversal of auxilliary parsers.
Chris@16:     //
Chris@16:     ///////////////////////////////////////////////////////////////////////////
Chris@16:     struct post_order
Chris@16:     {
Chris@16:         //  Return the parser type, which is generated as the result of the
Chris@16:         //  traverse function below.
Chris@16: 
Chris@16:         template <typename MetaT, typename ParserT>
Chris@16:         struct result
Chris@16:         {
Chris@16:             typedef typename
Chris@16:                 traverse_post_order_return<
Chris@16:                     MetaT
Chris@16:                   , ParserT
Chris@16:                   , traverse_post_order_env<0, 0, 0, 0>
Chris@16:                 >::type
Chris@16:             type;
Chris@16:         };
Chris@16: 
Chris@16:         //  Traverse a given parser and refactor it with the help of the given
Chris@16:         //  MetaT metafunction template.
Chris@16: 
Chris@16:         template <typename MetaT, typename ParserT>
Chris@16:         static typename result<MetaT, ParserT>::type
Chris@16:         traverse(MetaT const &meta_, ParserT const &parser_)
Chris@16:         {
Chris@16:             typedef typename ParserT::parser_category_t parser_category_t;
Chris@16:             return impl::traverse_post_order<parser_category_t>::generate(
Chris@16:                 meta_, parser_, traverse_post_order_env<0, 0, 0, 0>());
Chris@16:         }
Chris@16:     };
Chris@16: 
Chris@16:     ///////////////////////////////////////////////////////////////////////////
Chris@16:     //
Chris@16:     //  Transform policies
Chris@16:     //
Chris@16:     //      The following policy classes could be used to assemble some new
Chris@16:     //      transformation metafunction which uses identity transformations
Chris@16:     //      for some parser_category type parsers.
Chris@16:     //
Chris@16:     ///////////////////////////////////////////////////////////////////////////
Chris@16: 
Chris@16:     ///////////////////////////////////////////////////////////////////////////
Chris@16:     //  transform plain parsers
Chris@16:     template <typename TransformT>
Chris@16:     struct plain_identity_policy
Chris@16:     {
Chris@16:         template <typename ParserT, typename EnvT>
Chris@16:         struct plain_result
Chris@16:         {
Chris@16:             // plain parsers should be embedded and returned correctly
Chris@16:             typedef typename ParserT::embed_t type;
Chris@16:         };
Chris@16: 
Chris@16:         template <typename ParserT, typename EnvT>
Chris@16:         typename parser_traversal_plain_result<TransformT, ParserT, EnvT>::type
Chris@16:         generate_plain(ParserT const &parser_, EnvT const& /*env*/) const
Chris@16:         {
Chris@16:             return parser_;
Chris@16:         }
Chris@16:     };
Chris@16: 
Chris@16:     //////////////////////////////////
Chris@16:     //  transform unary parsers
Chris@16:     template <typename UnaryT, typename SubjectT>
Chris@16:     struct unary_identity_policy_return
Chris@16:     {
Chris@16:         typedef typename UnaryT::parser_generator_t parser_generator_t;
Chris@16:         typedef typename parser_generator_t
Chris@16:             ::template result<SubjectT>::type type;
Chris@16:     };
Chris@16: 
Chris@16:     template <typename TransformT>
Chris@16:     struct unary_identity_policy
Chris@16:     {
Chris@16:         template <typename UnaryT, typename SubjectT, typename EnvT>
Chris@16:         struct unary_result
Chris@16:         {
Chris@16:             typedef
Chris@16:                 typename unary_identity_policy_return<UnaryT, SubjectT>::type
Chris@16:             type;
Chris@16:         };
Chris@16: 
Chris@16:         template <typename UnaryT, typename SubjectT, typename EnvT>
Chris@16:         typename parser_traversal_unary_result<
Chris@16:             TransformT, UnaryT, SubjectT, EnvT>::type
Chris@16:         generate_unary(
Chris@16:             UnaryT const &, SubjectT const &subject_, EnvT const& /*env*/) const
Chris@16:         {
Chris@16:             typedef typename UnaryT::parser_generator_t parser_generator_t;
Chris@16:             return parser_generator_t::template generate<SubjectT>(subject_);
Chris@16:         }
Chris@16:     };
Chris@16: 
Chris@16:     //////////////////////////////////
Chris@16:     //  transform action parsers
Chris@16:     template <typename TransformT>
Chris@16:     struct action_identity_policy
Chris@16:     {
Chris@16:         template <typename ActionT, typename SubjectT, typename EnvT>
Chris@16:         struct action_result
Chris@16:         {
Chris@16:             typedef action<SubjectT, typename ActionT::predicate_t> type;
Chris@16:         };
Chris@16: 
Chris@16:         template <typename ActionT, typename SubjectT, typename EnvT>
Chris@16:         typename parser_traversal_action_result<
Chris@16:             TransformT, ActionT, SubjectT, EnvT
Chris@16:         >::type
Chris@16:         generate_action(ActionT const &action_, SubjectT const &subject_,
Chris@16:             EnvT const& /*env*/) const
Chris@16:         {
Chris@16:             return subject_[action_.predicate()];
Chris@16:         }
Chris@16:     };
Chris@16: 
Chris@16:     //////////////////////////////////
Chris@16:     //  transform binary parsers
Chris@16:     template <typename BinaryT, typename LeftT, typename RightT>
Chris@16:     struct binary_identity_policy_return
Chris@16:     {
Chris@16:         typedef typename BinaryT::parser_generator_t parser_generator_t;
Chris@16:         typedef typename parser_generator_t
Chris@16:             ::template result<LeftT, RightT>::type type;
Chris@16:     };
Chris@16: 
Chris@16:     template <typename TransformT>
Chris@16:     struct binary_identity_policy
Chris@16:     {
Chris@16:         template <typename BinaryT, typename LeftT
Chris@16:             , typename RightT, typename EnvT>
Chris@16:         struct binary_result {
Chris@16: 
Chris@16:             typedef typename
Chris@16:                 binary_identity_policy_return<BinaryT, LeftT, RightT>::type
Chris@16:             type;
Chris@16:         };
Chris@16: 
Chris@16:         template <typename BinaryT, typename LeftT
Chris@16:             , typename RightT, typename EnvT>
Chris@16:         typename parser_traversal_binary_result<
Chris@16:             TransformT, BinaryT, LeftT, RightT, EnvT
Chris@16:         >::type
Chris@16:         generate_binary(
Chris@16:             BinaryT const &, LeftT const& left_
Chris@16:           , RightT const& right_, EnvT const& /*env*/) const
Chris@16:         {
Chris@16:             typedef typename BinaryT::parser_generator_t parser_generator_t;
Chris@16:             return parser_generator_t::
Chris@16:                 template generate<LeftT, RightT>(left_, right_);
Chris@16:         }
Chris@16:     };
Chris@16: 
Chris@16:     ///////////////////////////////////////////////////////////////////////////
Chris@16:     //
Chris@16:     //  transform_policies template
Chris@16:     //
Chris@16:     //      The transform_policies template metafunction could serve as a
Chris@16:     //      base class for new metafunctions to be passed to the traverse meta
Chris@16:     //      template (see above), where only minimal parts have to be
Chris@16:     //      overwritten.
Chris@16:     //
Chris@16:     ///////////////////////////////////////////////////////////////////////////
Chris@16: 
Chris@16:     template <
Chris@16:         typename TransformT,
Chris@16:         typename PlainPolicyT = plain_identity_policy<TransformT>,
Chris@16:         typename UnaryPolicyT = unary_identity_policy<TransformT>,
Chris@16:         typename ActionPolicyT = action_identity_policy<TransformT>,
Chris@16:         typename BinaryPolicyT = binary_identity_policy<TransformT>
Chris@16:     >
Chris@16:     struct transform_policies :
Chris@16:         public PlainPolicyT,
Chris@16:         public UnaryPolicyT,
Chris@16:         public ActionPolicyT,
Chris@16:         public BinaryPolicyT
Chris@16:     {
Chris@16:     };
Chris@16: 
Chris@16:     ///////////////////////////////////////////////////////////////////////////
Chris@16:     //
Chris@16:     //  Identity transformation
Chris@16:     //
Chris@16:     //      The identity_transform metafunction supplied to the traverse
Chris@16:     //      template will generate a new parser, which will be exactly
Chris@16:     //      identical to the parser given as the parameter to the traverse
Chris@16:     //      metafunction. I.e. the following conceptual 'equation' will be
Chris@16:     //      always true:
Chris@16:     //
Chris@16:     //      some_parser ==
Chris@16:     //          post_order::traverse(identity_transform(), some_parser)
Chris@16:     //
Chris@16:     ///////////////////////////////////////////////////////////////////////////
Chris@16: 
Chris@16:     struct identity_transform : transform_policies<identity_transform> {};
Chris@16: 
Chris@16: BOOST_SPIRIT_CLASSIC_NAMESPACE_END
Chris@16: 
Chris@16: }} // namespace BOOST_SPIRIT_CLASSIC_NS
Chris@16: 
Chris@16: #endif // !defined(BOOST_SPIRIT_TRAVERSE_HPP)