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Filename : subrule.hpp
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/*=============================================================================
    Copyright (c) 2002-2003 Joel de Guzman
    Copyright (c) 2002-2003 Hartmut Kaiser
    http://spirit.sourceforge.net/

  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)
=============================================================================*/
#if !defined(BOOST_SPIRIT_SUBRULE_HPP)
#define BOOST_SPIRIT_SUBRULE_HPP

#include <boost/config.hpp>
#include <boost/static_assert.hpp>
#include <boost/mpl/if.hpp>
#include <boost/mpl/bool.hpp>
#include <boost/type_traits/is_same.hpp>

#include <boost/spirit/home/classic/namespace.hpp>
#include <boost/spirit/home/classic/core/parser.hpp>
#include <boost/spirit/home/classic/core/non_terminal/parser_context.hpp>

#include <boost/spirit/home/classic/core/non_terminal/subrule_fwd.hpp>
#include <boost/spirit/home/classic/core/non_terminal/impl/subrule.ipp>

namespace boost { namespace spirit {

BOOST_SPIRIT_CLASSIC_NAMESPACE_BEGIN

    ///////////////////////////////////////////////////////////////////////////
    //
    //  subrules_scanner class
    //
    ///////////////////////////////////////////////////////////////////////////
    template <typename ScannerT, typename ListT>
    struct subrules_scanner : public ScannerT
    {
        typedef ScannerT                            scanner_t;
        typedef ListT                               list_t;
        typedef subrules_scanner<ScannerT, ListT>   self_t;

        subrules_scanner(ScannerT const& scan, ListT const& list_)
        : ScannerT(scan), list(list_) {}

        template <typename PoliciesT>
        struct rebind_policies
        {
            typedef typename rebind_scanner_policies<ScannerT, PoliciesT>::type
                rebind_scanner;
            typedef subrules_scanner<rebind_scanner, ListT> type;
        };

        template <typename PoliciesT>
        subrules_scanner<
            typename rebind_scanner_policies<ScannerT, PoliciesT>::type,
            ListT>
        change_policies(PoliciesT const& policies) const
        {
            typedef subrules_scanner<
                BOOST_DEDUCED_TYPENAME
                    rebind_scanner_policies<ScannerT, PoliciesT>::type,
                ListT>
            subrules_scanner_t;

            return subrules_scanner_t(
                    ScannerT::change_policies(policies),
                    list);
        }

        template <typename IteratorT>
        struct rebind_iterator
        {
            typedef typename rebind_scanner_iterator<ScannerT, IteratorT>::type
                rebind_scanner;
            typedef subrules_scanner<rebind_scanner, ListT> type;
        };

        template <typename IteratorT>
        subrules_scanner<
            typename rebind_scanner_iterator<ScannerT, IteratorT>::type,
            ListT>
        change_iterator(IteratorT const& first, IteratorT const &last) const
        {
            typedef subrules_scanner<
                BOOST_DEDUCED_TYPENAME
                    rebind_scanner_iterator<ScannerT, IteratorT>::type,
                ListT>
            subrules_scanner_t;

            return subrules_scanner_t(
                    ScannerT::change_iterator(first, last),
                    list);
        }

        ListT const& list;
    };

    ///////////////////////////////////////////////////////////////////////////
    //
    //  subrule_scanner type computer class
    //
    //      This computer ensures that the scanner will not be recursively
    //      instantiated if it's not needed.
    //
    ///////////////////////////////////////////////////////////////////////////
    template <typename ScannerT, typename ListT>
    struct subrules_scanner_finder
    {
          typedef subrules_scanner<ScannerT, ListT> type;
    };

    template <typename ScannerT, typename ListT>
    struct subrules_scanner_finder<subrules_scanner<ScannerT, ListT>, ListT>
    {
          typedef subrules_scanner<ScannerT, ListT> type;
    };

    ///////////////////////////////////////////////////////////////////////////
    //
    //  subrule_list class
    //
    ///////////////////////////////////////////////////////////////////////////
    template <typename FirstT, typename RestT>
    struct subrule_list : public parser<subrule_list<FirstT, RestT> >
    {
        typedef subrule_list<FirstT, RestT> self_t;
        typedef FirstT                      first_t;
        typedef RestT                       rest_t;

        subrule_list(FirstT const& first_, RestT const& rest_)
        : first(first_), rest(rest_) {}

        template <typename ScannerT>
        struct result
        {
            typedef typename parser_result<FirstT, ScannerT>::type type;
        };

        template <typename ScannerT>
        typename parser_result<self_t, ScannerT>::type
        parse(ScannerT const& scan) const
        {
            typedef typename subrules_scanner_finder<ScannerT, self_t>::type
            subrules_scanner_t;
            subrules_scanner_t g_arg(scan, *this);
            return first.start.parse(g_arg);
        }

        template <int ID, typename DefT, typename ContextT>
        subrule_list<
            FirstT,
            subrule_list<
                subrule_parser<ID, DefT, ContextT>,
                RestT> >
        operator,(subrule_parser<ID, DefT, ContextT> const& rhs_)
        {
            return subrule_list<
                FirstT,
                subrule_list<
                    subrule_parser<ID, DefT, ContextT>,
                    RestT> >(
                        first,
                        subrule_list<
                            subrule_parser<ID, DefT, ContextT>,
                            RestT>(rhs_, rest));
        }

        FirstT first;
        RestT rest;
    };

    ///////////////////////////////////////////////////////////////////////////
    //
    //  subrule_parser class
    //
    ///////////////////////////////////////////////////////////////////////////
    template <int ID, typename DefT, typename ContextT>
    struct subrule_parser
    : public parser<subrule_parser<ID, DefT, ContextT> >
    {
        typedef subrule_parser<ID, DefT, ContextT> self_t;
        typedef subrule<ID, ContextT> subrule_t;
        typedef DefT def_t;

        BOOST_STATIC_CONSTANT(int, id = ID);

        template <typename ScannerT>
        struct result
        {
            typedef typename
                impl::get_subrule_parser_result<
                    DefT, ScannerT, typename subrule_t::attr_t>::type type;
        };

        subrule_parser(subrule_t const& start_, DefT const& rhs_)
        : rhs(rhs_), start(start_) {}

        template <typename ScannerT>
        typename parser_result<self_t, ScannerT>::type
        parse(ScannerT const& scan) const
        {
            // This will only be called when parsing single subrules.
            typedef subrule_list<self_t, nil_t> list_t;
            typedef subrules_scanner<ScannerT, list_t> scanner_t;

            list_t    list(*this, nil_t());
            scanner_t g_arg(scan, list);
            return start.parse(g_arg);
        }

        template <int ID2, typename DefT2, typename ContextT2>
        inline subrule_list<
            self_t,
            subrule_list<
                subrule_parser<ID2, DefT2, ContextT2>,
                nil_t> >
        operator,(subrule_parser<ID2, DefT2, ContextT2> const& rhs) const
        {
            return subrule_list<
                self_t,
                subrule_list<
                    subrule_parser<ID2, DefT2, ContextT2>,
                    nil_t> >(
                        *this,
                        subrule_list<
                            subrule_parser<ID2, DefT2, ContextT2>, nil_t>(
                                rhs, nil_t()));
        }

        typename DefT::embed_t rhs;
        subrule_t const& start;
    };

    ///////////////////////////////////////////////////////////////////////////
    //
    //  subrule class
    //
    ///////////////////////////////////////////////////////////////////////////
    template <int ID, typename ContextT>
    struct subrule
        : public parser<subrule<ID, ContextT> >
        , public ContextT::base_t
        , public context_aux<ContextT, subrule<ID, ContextT> >
    {
        typedef subrule<ID, ContextT> self_t;
        typedef subrule<ID, ContextT> const&  embed_t;

        typedef typename ContextT::context_linker_t context_t;
        typedef typename context_t::attr_t attr_t;

        BOOST_STATIC_CONSTANT(int, id = ID);

        template <typename ScannerT>
        struct result
        {
            typedef typename
                impl::get_subrule_result<ID, ScannerT, attr_t>::type type;
        };

        template <typename ScannerT>
        typename parser_result<self_t, ScannerT>::type
        parse_main(ScannerT const& scan) const
        {
            typedef typename parser_result<self_t, ScannerT>::type result_t;
            result_t result_;
            impl::parse_subrule<result_t, ScannerT, ID>::
                do_(result_, scan);
            return result_;
        }

        template <typename ScannerT>
        typename parser_result<self_t, ScannerT>::type
        parse(ScannerT const& scan) const
        {
            typedef typename parser_result<self_t, ScannerT>::type result_t;
            typedef parser_scanner_linker<ScannerT> scanner_t;
            BOOST_SPIRIT_CONTEXT_PARSE(
                scan, *this, scanner_t, context_t, result_t);
        }

        template <typename DefT>
        subrule_parser<ID, DefT, ContextT>
        operator=(parser<DefT> const& rhs) const
        {
            return subrule_parser<ID, DefT, ContextT>(*this, rhs.derived());
        }

    private:

        //  assignment of subrules is not allowed. Use subrules
        //  with identical IDs if you want to have aliases.

        subrule& operator=(subrule const&);

        template <int ID2, typename ContextT2>
        subrule& operator=(subrule<ID2, ContextT2> const&);
    };

BOOST_SPIRIT_CLASSIC_NAMESPACE_END

}} // namespace BOOST_SPIRIT_CLASSIC_NS

#endif