001/*
002 * (C) Copyright 2006-2011 Nuxeo SA (http://nuxeo.com/) and others.
003 *
004 * Licensed under the Apache License, Version 2.0 (the "License");
005 * you may not use this file except in compliance with the License.
006 * You may obtain a copy of the License at
007 *
008 *     http://www.apache.org/licenses/LICENSE-2.0
009 *
010 * Unless required by applicable law or agreed to in writing, software
011 * distributed under the License is distributed on an "AS IS" BASIS,
012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013 * See the License for the specific language governing permissions and
014 * limitations under the License.
015 * 
016 * Contributors:
017 *     bstefanescu
018 *
019 * $Id$
020 */
021
022package org.nuxeo.common.collections;
023
024import java.util.HashMap;
025
026/**
027 * A Class keyed map sensitive to class hierarchy. This map provides an additional method {@link #find(Class)} that can
028 * be used to lookup a class compatible to the given one depending on the class hierarchy.
029 *
030 * @author <a href="mailto:bs@nuxeo.com">Bogdan Stefanescu</a>
031 */
032public class ClassMap<T> extends HashMap<Class<?>, T> {
033
034    private static final long serialVersionUID = 1L;
035
036    public T find(Class<?> key) {
037        T v = get(key);
038        if (v == null) {
039            Class<?> sk = key.getSuperclass();
040            if (sk != null) {
041                v = get(sk);
042            }
043            Class<?>[] itfs = null;
044            if (v == null) { // try interfaces
045                itfs = key.getInterfaces();
046                for (Class<?> itf : itfs) {
047                    v = get(itf);
048                    if (v != null) {
049                        break;
050                    }
051                }
052            }
053            if (v == null) {
054                if (sk != null) { // superclass
055                    v = find(sk);
056                }
057                if (v == null) { // interfaces
058                    for (Class<?> itf : itfs) {
059                        v = find(itf);
060                        if (v != null) {
061                            break;
062                        }
063                    }
064                }
065            }
066            if (v != null) {
067                put(key, v);
068            }
069        }
070        return v;
071    }
072
073}