/* * The Apache Software License, Version 1.1 * * Copyright (c) 1999 The Apache Software Foundation. All rights * reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in * the documentation and/or other materials provided with the * distribution. * * 3. The end-user documentation included with the redistribution, if * any, must include the following acknowlegement: * "This product includes software developed by the * Apache Software Foundation (http://www.apache.org/)." * Alternately, this acknowlegement may appear in the software itself, * if and wherever such third-party acknowlegements normally appear. * * 4. The names "The Jakarta Project", "Tomcat", and "Apache Software * Foundation" must not be used to endorse or promote products derived * from this software without prior written permission. For written * permission, please contact apache@apache.org. * * 5. Products derived from this software may not be called "Apache" * nor may "Apache" appear in their names without prior written * permission of the Apache Group. * * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE * DISCLAIMED. IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. * ==================================================================== * * This software consists of voluntary contributions made by many * individuals on behalf of the Apache Software Foundation. For more * information on the Apache Software Foundation, please see * <http://www.apache.org/>. * */ package org.jbpm.jpdl.el.impl; import java.util.Collection; import java.util.Enumeration; import java.util.HashMap; import java.util.Map; import java.util.Set; /** * * <p>This is a Map implementation driven by a data source that only * provides an enumeration of keys and a getValue(key) method. This * class must be subclassed to implement those methods. * * <p>Some of the methods may incur a performance penalty that * involves enumerating the entire data source. In these cases, the * Map will try to save the results of that enumeration, but only if * the underlying data source is immutable. * * @author Nathan Abramson - Art Technology Group * @version $Change: 181177 $$DateTime: 2001/06/26 08:45:09 $$Author$ **/ public abstract class EnumeratedMap implements Map { //------------------------------------- // Member variables //------------------------------------- Map mMap; //------------------------------------- public void clear () { throw new UnsupportedOperationException (); } //------------------------------------- public boolean containsKey (Object pKey) { return getValue (pKey) != null; } //------------------------------------- public boolean containsValue (Object pValue) { return getAsMap ().containsValue (pValue); } //------------------------------------- public Set entrySet () { return getAsMap ().entrySet (); } //------------------------------------- public Object get (Object pKey) { return getValue (pKey); } //------------------------------------- public boolean isEmpty () { return !enumerateKeys ().hasMoreElements (); } //------------------------------------- public Set keySet () { return getAsMap ().keySet (); } //------------------------------------- public Object put (Object pKey, Object pValue) { throw new UnsupportedOperationException (); } //------------------------------------- public void putAll (Map pMap) { throw new UnsupportedOperationException (); } //------------------------------------- public Object remove (Object pKey) { throw new UnsupportedOperationException (); } //------------------------------------- public int size () { return getAsMap ().size (); } //------------------------------------- public Collection values () { return getAsMap ().values (); } //------------------------------------- // Abstract methods //------------------------------------- /** * * Returns an enumeration of the keys **/ public abstract Enumeration enumerateKeys (); //------------------------------------- /** * * Returns true if it is possible for this data source to change **/ public abstract boolean isMutable (); //------------------------------------- /** * * Returns the value associated with the given key, or null if not * found. **/ public abstract Object getValue (Object pKey); //------------------------------------- /** * * Converts the MapSource to a Map. If the map is not mutable, this * is cached **/ public Map getAsMap () { if (mMap != null) { return mMap; } else { Map m = convertToMap (); if (!isMutable ()) { mMap = m; } return m; } } //------------------------------------- /** * * Converts to a Map **/ Map convertToMap () { Map ret = new HashMap (); for (Enumeration e = enumerateKeys (); e.hasMoreElements (); ) { Object key = e.nextElement (); Object value = getValue (key); ret.put (key, value); } return ret; } //------------------------------------- }