libs/spirit/example/qi/compiler_tutorial/calc8/annotation.hpp

/*=============================================================================
    Copyright (c) 2001-2011 Joel de Guzman

    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_CALC8_ANNOTATION_HPP)
#define BOOST_SPIRIT_CALC8_ANNOTATION_HPP

#include <map>
#include <boost/variant/apply_visitor.hpp>
#include <boost/type_traits/is_base_of.hpp>
#include <boost/mpl/bool.hpp>
#include "ast.hpp"

namespace client
{
    ///////////////////////////////////////////////////////////////////////////////
    //  The annotation handler links the AST to a map of iterator positions
    //  for the purpose of subsequent semantic error handling when the
    //  program is being compiled.
    ///////////////////////////////////////////////////////////////////////////////
    template <typename Iterator>
    struct annotation
    {
        template <typename, typename>
        struct result { typedef void type; };

        std::vector<Iterator>& iters;
        annotation(std::vector<Iterator>& iters)
          : iters(iters) {}

        struct set_id
        {
            typedef void result_type;

            int id;
            set_id(int id) : id(id) {}

            template <typename T>
            void operator()(T& x) const
            {
                this->dispatch(x, boost::is_base_of<ast::tagged, T>());
            }

            // This will catch all nodes except those inheriting from ast::tagged
            template <typename T>
            void dispatch(T& x, boost::mpl::false_) const
            {
                // (no-op) no need for tags
            }

            // This will catch all nodes inheriting from ast::tagged
            template <typename T>
            void dispatch(T& x, boost::mpl::true_) const
            {
                x.id = id;
            }
        };

        void operator()(ast::operand& ast, Iterator pos) const
        {
            int id = iters.size();
            iters.push_back(pos);
            boost::apply_visitor(set_id(id), ast);
        }

        void operator()(ast::assignment& ast, Iterator pos) const
        {
            int id = iters.size();
            iters.push_back(pos);
            ast.lhs.id = id;
        }
    };
}

#endif