MultiTaskListener.java revision 3019:176472b94f2e 
1/*
2 * Copyright (c) 2011, 2012, 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.  Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26package com.sun.tools.javac.api;
27
28import java.util.Arrays;
29import java.util.Collection;
30
31import com.sun.source.util.TaskEvent;
32import com.sun.source.util.TaskListener;
33import com.sun.tools.javac.util.Context;
34import com.sun.tools.javac.util.DefinedBy;
35import com.sun.tools.javac.util.DefinedBy.Api;
36
37/**
38 * A collection of currently registered {@link TaskListener}s. Events passed to this TaskListener
39 * will be forwarded to all the registered TaskListeners.
40 *
41 * <p><b>This is NOT part of any supported API.
42 * If you write code that depends on this, you do so at your own risk.
43 * This code and its internal interfaces are subject to change or
44 * deletion without notice.</b>
45 */
46public class MultiTaskListener implements TaskListener {
47    /** The context key for the MultiTaskListener. */
48    public static final Context.Key<MultiTaskListener> taskListenerKey = new Context.Key<>();
49
50    /** Empty array of task listeners */
51    private static final TaskListener[] EMPTY_LISTENERS = new TaskListener[0];
52
53    /** Get the MultiTaskListener instance for this context. */
54    public static MultiTaskListener instance(Context context) {
55        MultiTaskListener instance = context.get(taskListenerKey);
56        if (instance == null)
57            instance = new MultiTaskListener(context);
58        return instance;
59    }
60
61    protected MultiTaskListener(Context context) {
62        context.put(taskListenerKey, this);
63        ccw = ClientCodeWrapper.instance(context);
64    }
65
66    /**
67     * The current set of registered listeners.
68     * This is a mutable reference to an immutable array.
69     */
70    TaskListener[] listeners = EMPTY_LISTENERS;
71
72    ClientCodeWrapper ccw;
73
74    public Collection<TaskListener> getTaskListeners() {
75        return Arrays.asList(listeners);
76    }
77
78    public boolean isEmpty() {
79        return listeners == EMPTY_LISTENERS;
80    }
81
82    public void add(TaskListener listener) {
83        for (TaskListener l: listeners) {
84            if (ccw.unwrap(l) == listener)
85                throw new IllegalStateException();
86        }
87        listeners = Arrays.copyOf(listeners, listeners.length + 1);
88        listeners[listeners.length - 1] = ccw.wrap(listener);
89    }
90
91    public void remove(TaskListener listener) {
92        for (int i = 0; i < listeners.length; i++) {
93            if (ccw.unwrap(listeners[i]) == listener) {
94                if (listeners.length == 1) {
95                    listeners = EMPTY_LISTENERS;
96                } else {
97                    TaskListener[] newListeners = new TaskListener[listeners.length - 1];
98                    System.arraycopy(listeners, 0, newListeners, 0, i);
99                    System.arraycopy(listeners, i + 1, newListeners, i, newListeners.length - i);
100                    listeners = newListeners;
101                }
102                break;
103            }
104        }
105    }
106
107    @Override @DefinedBy(Api.COMPILER_TREE)
108    public void started(TaskEvent e) {
109        // guard against listeners being updated by a listener
110        TaskListener[] ll = this.listeners;
111        for (TaskListener l: ll)
112            l.started(e);
113    }
114
115    @Override @DefinedBy(Api.COMPILER_TREE)
116    public void finished(TaskEvent e) {
117        // guard against listeners being updated by a listener
118        TaskListener[] ll = this.listeners;
119        for (TaskListener l: ll)
120            l.finished(e);
121    }
122
123    @Override
124    public String toString() {
125        return Arrays.toString(listeners);
126    }
127
128    public void clear() {
129        listeners = EMPTY_LISTENERS;
130    }
131}
132