001    /*
002      Copyright (C) 2001 Laurent Martelli <laurent@aopsys.com>
003    
004      This program is free software; you can redistribute it and/or modify
005      it under the terms of the GNU Lesser General Public License as
006      published by the Free Software Foundation; either version 2 of the
007      License, or (at your option) any later version.
008    
009      This program is distributed in the hope that it will be useful,
010      but WITHOUT ANY WARRANTY; without even the implied warranty of
011      MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
012      GNU Lesser General Public License for more details.
013    
014      You should have received a copy of the GNU Lesser General Public License
015      along with this program; if not, write to the Free Software
016      Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA */
017    
018    package org.objectweb.jac.util;
019    
020    import java.util.HashMap;
021    import java.util.Map;
022    import org.apache.log4j.Logger;
023    
024    
025    /**
026     * Use only put(Object,Object) and get(Object). 
027     */
028    public class LinkedMap extends HashMap {
029        static Logger logger = Logger.getLogger("util.map");
030    
031        Map next;
032        public LinkedMap() {
033        }
034        public LinkedMap(Map next) {
035            this.next = next;
036        }
037        public Object get(Object key) {
038            if (super.containsKey(key)) {
039                return super.get(key);
040            } else {
041                Object result = null;
042                if (next!=null) {
043                    result = next.get(key);
044                    logger.debug(key+" not found, trying next -> "+result);
045                    put(key,result);
046                }
047                return result;
048            }
049        }
050        public boolean containsKey(Object key) {
051            if (super.containsKey(key)) {
052                return true;
053            } else {
054                return next!=null && next.containsKey(key);
055            }
056        }
057    }