follow_list.h

/***************************************************************************
 *   Copyright (C) 2006 by Radko Mihal                                     *
 *   rmihal@pobox.sk                                                       *
 *                                                                         *
 *   This program is free software; you can redistribute it and/or modify  *
 *   it under the terms of the GNU General Public License as published by  *
 *   the Free Software Foundation; either version 2 of the License, or     *
 *   (at your option) any later version.                                   *
 *                                                                         *
 *   This program is distributed in the hope that it will be useful,       *
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of        *
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         *
 *   GNU General Public License for more details.                          *
 *                                                                         *
 *   You should have received a copy of the GNU General Public License     *
 *   along with this program; if not, write to the                         *
 *   Free Software Foundation, Inc.,                                       *
 *   51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA.              *
 ***************************************************************************/
#ifndef BRACKET_EXPRESSIONFOLLOW_LIST_H
#define BRACKET_EXPRESSIONFOLLOW_LIST_H

namespace bracket_expression {

template<typename E>
class follow_list
{
typedef typename grammar_to_parser::basic_parser<E>::parser_list
                                                                                                                                parser_list;
public:
        class follow_list_and_expression_term
        {
                grammar_to_parser::basic_choice<E,follow_list<E> >                      m_follow_list;
                grammar_to_parser::basic_choice<E,expression_term<E> >          m_expression_term;
                
        public:
                unsigned long recognize( const E* buf, const unsigned long buf_length )
                {
                        unsigned long size = m_follow_list->recognize(buf,buf_length);
                        if( size == 0 )
                        {
                                size = m_expression_term->recognize(buf,buf_length);
                        }
                        return size;
                }
                
                follow_list_and_expression_term() {};
                ~follow_list_and_expression_term() {};
                void push_parsers( parser_list &l )
                {
                        l.push_back( &m_expression_term );
                        l.push_back( &m_follow_list );
                }       
        
        };
        
        grammar_to_parser::basic_choice<E,expression_term<E> >                                  
                                                                                                                m_expression_term;
        grammar_to_parser::basic_non_terminal<E,follow_list_and_expression_term >
                                                                                                                m_follow_and_expression;
        
public:
        unsigned long recognize( const E* buf, const unsigned long buf_length )
        {
                if( m_expression_term.is_parsed() )
                {
                        return m_expression_term->recognize(buf,buf_length);
                }
                else
                {
                        return m_follow_and_expression->recognize(buf,buf_length);
                }
        }
        
public:
    follow_list() : m_follow_and_expression() {};

    ~follow_list() {};

        void push_parsers( parser_list &l )
        {
                l.push_back( &m_follow_and_expression );
                l.push_back( &m_expression_term );
        }       
};

};

#endif

---