simple_choice.h

/***************************************************************************
 *   Copyright (C) 2005 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 GRAMMAR_TO_PARSERBASIC_SIMPLE_CHOICE_H
#define GRAMMAR_TO_PARSERBASIC_SIMPLE_CHOICE_H

namespace grammar_to_parser {

const char* SIMPLE_CHOICE = "SimpleChoice";

template< typename E >
class basic_simple_choice : public basic_simple_non_terminal<E>
{
public:
typedef typename basic_parser<E>::parser_list parser_list;
typedef typename basic_parser<E>::parser_list_iterator parser_list_iterator;

        basic_simple_choice() : basic_simple_non_terminal<E>()
        {
                set_name(SIMPLE_CHOICE);
        };
        
        unsigned long parse( const E* buf, const unsigned long buf_length )
        {
                prepare_for_parsing();
                parser_list_iterator it = m_parser_list.begin();

                m_is_parsed = false;
                while( it != m_parser_list.end() && !m_is_parsed )
                {
                        (*it)->parse( buf + m_parsed_size, buf_length - m_parsed_size );
                        if( (*it)->is_parsed() ) 
                        {
                                m_is_parsed = true;
                                m_parsed_size += (*it)->parsed_size();
                        }
                        it++;
                }
                // unset 'parsed' flag for rest (for parser reuse)
                while( it != m_parser_list.end() )
                {
                        (*it)->invalidate();
                }
                return m_parsed_size;
        }
        virtual std::basic_istream<E>& parse( std::basic_istream<E>& is )
        {
                prepare_for_parsing();
                parser_list_iterator it = m_parser_list.begin();
                std::streampos pos = is.tellg();

                m_is_parsed = false;
                while( it != m_parser_list.end() && !m_is_parsed )
                {
                        (*it)->parse( is );
                        if( (*it)->is_parsed() ) 
                        {
                                m_is_parsed = true;
                                m_parsed_size += (*it)->parsed_size();
                        }
                        it++;
                }
                // unset 'parsed' flag for rest (for parser reuse)
                while( it != m_parser_list.end() )
                {
                        (*it++)->invalidate();
                }

                if( !m_is_parsed )
                {
                        is.clear();
                        is.seekg( pos );
                }
                return is;
        }
};


typedef basic_simple_choice<char> simple_choice;
typedef basic_simple_choice<wchar_t> wsimple_choice;

};

#endif

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