1/* 2 * Copyright (c) 2011, 2015, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24package com.sun.hotspot.igv.util; 25 26import java.util.HashMap; 27import java.util.Map; 28import org.openide.util.Lookup.Result; 29import org.openide.util.LookupEvent; 30import org.openide.util.LookupListener; 31import org.openide.util.Utilities; 32 33/** 34 * 35 * @author Thomas 36 */ 37public class LookupHistory { 38 39 private static Map<Class, LookupHistoryImpl> cache = new HashMap<>(); 40 41 private static class LookupHistoryImpl<T> implements LookupListener { 42 43 private Class<T> klass; 44 private Result<T> result; 45 private T last; 46 47 public LookupHistoryImpl(Class<T> klass) { 48 this.klass = klass; 49 result = Utilities.actionsGlobalContext().lookupResult(klass); 50 result.addLookupListener(this); 51 last = Utilities.actionsGlobalContext().lookup(klass); 52 } 53 54 public T getLast() { 55 return last; 56 } 57 58 @Override 59 public void resultChanged(LookupEvent ev) { 60 T current = Utilities.actionsGlobalContext().lookup(klass); 61 if (current != null) { 62 last = current; 63 } 64 } 65 } 66 67 public static <T> void init(Class<T> klass) { 68 if (!cache.containsKey(klass)) { 69 cache.put(klass, new LookupHistoryImpl<>(klass)); 70 } 71 } 72 73 @SuppressWarnings("unchecked") 74 public static <T> T getLast(Class<T> klass) { 75 init(klass); 76 assert cache.containsKey(klass); 77 return (T) cache.get(klass).getLast(); 78 } 79} 80