001 /* 002 Copyright (C) 2001 Laurent Martelli 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; 021 022 023 /** 024 * Implements a map whose data may be shared between several 025 * instances. It has the benefit of having a fast clone() method which 026 * only duplicates the data when needed. 027 */ 028 public class SharedMap implements Cloneable { 029 HashMap map; 030 boolean shared=false; 031 public SharedMap() { 032 map = new HashMap(); 033 } 034 public SharedMap(HashMap map) { 035 this.map = map; 036 } 037 SharedMap(HashMap map, boolean shared) { 038 this.map = map; 039 this.shared = shared; 040 } 041 public Object clone() { 042 shared = true; 043 return new SharedMap(map,true); 044 } 045 public Object get(Object key) { 046 return map.get(key); 047 } 048 public synchronized void put(Object key, Object value) { 049 if (shared) { 050 //System.out.println("cloning shared map"); 051 map = (HashMap)map.clone(); 052 shared = false; 053 } 054 map.put(key,value); 055 } 056 }