001/*
002 *  gnu/regexp/CharIndexedString.java
003 *  Copyright (C) 1998-2001 Wes Biggs
004 *
005 *  This library is free software; you can redistribute it and/or modify
006 *  it under the terms of the GNU Lesser General Public License as published
007 *  by the Free Software Foundation; either version 2.1 of the License, or
008 *  (at your option) any later version.
009 *
010 *  This library is distributed in the hope that it will be useful,
011 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
012 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
013 *  GNU Lesser General Public License for more details.
014 *
015 *  You should have received a copy of the GNU Lesser General Public License
016 *  along with this program; if not, write to the Free Software
017 *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
018 */
019package gnu.regexp;
020import java.io.Serializable;
021
022class CharIndexedString implements CharIndexed, Serializable {
023    private String s;
024    private int anchor;
025    private int len;
026    
027    CharIndexedString(String str, int index) {
028        s = str;
029        len = s.length();
030        anchor = index;
031    }
032
033    public char charAt(int index) {
034        int pos = anchor + index;
035        return ((pos < len) && (pos >= 0)) ? s.charAt(pos) : OUT_OF_BOUNDS;
036    }
037    
038    public boolean isValid() {
039        return (anchor < len);
040    }
041    
042    public boolean move(int index) {
043        return ((anchor += index) < len);
044    }
045}