/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
 * C# Flex 1.4                                                             *
 * Copyright (C) 2004-2005  Jonathan Gilbert <logic@deltaq.org>            *
 * Derived from:                                                           *
 *                                                                         *
 *   JFlex 1.4                                                             *
 *   Copyright (C) 1998-2004  Gerwin Klein <lsf@jflex.de>                  *
 *   All rights reserved.                                                  *
 *                                                                         *
 * This program is free software; you can redistribute it and/or modify    *
 * it under the terms of the GNU General Public License. See the file      *
 * COPYRIGHT for more information.                                         *
 *                                                                         *
 * 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., *
 * 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA                 *
 *                                                                         *
 * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */

namespace CSFlex
{
    /**
     * Enumerator for the elements of a CharSet.
     *
     * Does not implement java.util.Enumeration, but supports the same protocol.
     *
     * @author Gerwin Klein
     * @version JFlex 1.4, $Revision: 2.2 $, $Date: 2004/04/12 10:07:47 $
     * @author Jonathan Gilbert
     * @version CSFlex 1.4
     */
    public sealed class CharSetEnumerator
    {
        private int index;
        private int offset;
        private long mask = 1;

        private CharSet set;

        public CharSetEnumerator(CharSet characters)
        {
            set = characters;

            while (index < set.bits.Length && set.bits[index] == 0)
                index++;

            if (index >= set.bits.Length)
                return;

            while (offset <= CharSet.MOD && ((set.bits[index] & mask) == 0))
            {
                mask <<= 1;
                offset++;
            }
        }

        private void advance()
        {
            do
            {
                offset++;
                mask <<= 1;
            } while (offset <= CharSet.MOD && ((set.bits[index] & mask) == 0));

            if (offset > CharSet.MOD)
            {
                do index++;
                while (index < set.bits.Length && set.bits[index] == 0);

                if (index >= set.bits.Length)
                    return;

                offset = 0;
                mask = 1;

                while (offset <= CharSet.MOD && ((set.bits[index] & mask) == 0))
                {
                    mask <<= 1;
                    offset++;
                }
            }
        }

        public bool hasMoreElements()
        {
            return index < set.bits.Length;
        }

        public int nextElement()
        {
            int x = (index << CharSet.BITS) + offset;
            advance();
            return x;
        }
    }
}
