number.h

/***************************************************************************
 *   Copyright (C) 2004-2006 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 NUMBER_H
#define NUMBER_H

// use for other then decimal numbers
template< class digit_choice, char prefix='x' >
class number
{
public:
        grammar_to_parser::terminal<'0'>                m_0;
        grammar_to_parser::terminal<prefix>     m_prefix;

        //digits->digit&digits | digit
        class digits
        {
                class digit_and_digits
                {
                        grammar_to_parser::choice< digit_choice >       m_digit;
                        grammar_to_parser::choice< digits >                     m_digits;
                public:
                        void push_parsers( grammar_to_parser::parsers& l )
                        {
                                l.push_back( &m_digit );
                                l.push_back( &m_digits );
                        }
                        unsigned long evaluate( unsigned long value, unsigned long &pow )
                        {
                                value = m_digits->evaluate( value, pow );
                                pow = pow*m_digit->get_base();
                                value += pow*m_digit->evaluate();
                                return value;
                        }

                };
                grammar_to_parser::non_terminal<digit_and_digits>
                                                                                                                m_digit_and_digits;
                grammar_to_parser::choice<digit_choice>                 m_digit;
        public:
                void push_parsers( grammar_to_parser::parsers &l )
                {
                        l.push_back( &m_digit_and_digits );
                        l.push_back( &m_digit );
                }
                unsigned long evaluate( unsigned long value, unsigned long &pow )
                {
                        if( m_digit.is_parsed() ) 
                        {
                                value = m_digit->evaluate();
                                pow = 1;
                                return value;
                        }
                        else
                        {
                                return m_digit_and_digits->evaluate( value, pow );
                        }
                }
        };
        grammar_to_parser::choice<digits>                                       m_digits;
public:
        void push_parsers( grammar_to_parser::parsers &l )
        {
                l.push_back( &m_0 );
                l.push_back( &m_prefix );
                l.push_back( &m_digits );
        }
        unsigned long evaluate()
        {
                unsigned long value=0;
                unsigned long pow=0;
                return m_digits->evaluate( value, pow );
        }
};

#endif

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