/*
 *  gnu/regexp/CharIndexedString.java
 *  Copyright (C) 1998-2001 Wes Biggs
 *
 *  This library is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU Lesser General Public License as published
 *  by the Free Software Foundation; either version 2.1 of the License, or
 *  (at your option) any later version.
 *
 *  This library 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 Lesser General Public License for more details.
 *
 *  You should have received a copy of the GNU Lesser General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */
package gnu.regexp;
import java.io.Serializable;

class CharIndexedString implements CharIndexed, Serializable {
    private String s;
    private int anchor;
    private int len;
    
    CharIndexedString(String str, int index) {
	s = str;
	len = s.length();
	anchor = index;
    }

    public char charAt(int index) {
	int pos = anchor + index;
	return ((pos < len) && (pos >= 0)) ? s.charAt(pos) : OUT_OF_BOUNDS;
    }
    
    public boolean isValid() {
	return (anchor < len);
    }
    
    public boolean move(int index) {
	return ((anchor += index) < len);
    }
}