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