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 
  26 package com.sun.tools.javac.api;
  27 
  28 import java.util.Arrays;
  29 import java.util.Collection;
  30 
  31 import com.sun.source.util.TaskEvent;
  32 import com.sun.source.util.TaskListener;
  33 import com.sun.tools.javac.util.Context;
  34 import com.sun.tools.javac.util.DefinedBy;
  35 import 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  */
  46 public 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 }