content: /*
   * Copyright (c) 2011, 2012, Oracle and/or its affiliates. All rights reserved.
   * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   *
   * This code is free software; you can redistribute it and/or modify it
   * under the terms of the GNU General Public License version 2 only, as
   * published by the Free Software Foundation.  Oracle designates this
   * particular file as subject to the "Classpath" exception as provided
   * by Oracle in the LICENSE file that accompanied this code.
   *
   * This code is distributed in the hope that it will be useful, but WITHOUT
   * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
   * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
   * version 2 for more details (a copy is included in the LICENSE file that
   * accompanied this code).
   *
   * You should have received a copy of the GNU General Public License version
   * 2 along with this work; if not, write to the Free Software Foundation,
   * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
   *
   * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
   * or visit www.oracle.com if you need additional information or have any
   * questions.
   */
  
  package openjdk.tools.javac.api;
  
  import java.util.Arrays;
  import java.util.Collection;
  
  import openjdk.source.util.TaskEvent;
  import openjdk.source.util.TaskListener;
  import openjdk.tools.javac.code.DeferredCompletionFailureHandler;
  import openjdk.tools.javac.code.DeferredCompletionFailureHandler.Handler;
  import openjdk.tools.javac.util.Context;
  import openjdk.tools.javac.util.DefinedBy;
  import openjdk.tools.javac.util.DefinedBy.Api;
  
  /**
   * A collection of currently registered {@link TaskListener}s. Events passed to this TaskListener
   * will be forwarded to all the registered TaskListeners.
   *
   * <p><b>This is NOT part of any supported API.
   * If you write code that depends on this, you do so at your own risk.
   * This code and its internal interfaces are subject to change or
   * deletion without notice.</b>
   */
  public class MultiTaskListener implements TaskListener {
      /** The context key for the MultiTaskListener. */
      public static final Context.Key<MultiTaskListener> taskListenerKey = new Context.Key<>();
  
      /** Empty array of task listeners */
      private static final TaskListener[] EMPTY_LISTENERS = new TaskListener[0];
  
      private final DeferredCompletionFailureHandler dcfh;
  
      /** Get the MultiTaskListener instance for this context. */
      public static MultiTaskListener instance(Context context) {
          MultiTaskListener instance = context.get(taskListenerKey);
          if (instance == null)
              instance = new MultiTaskListener(context);
          return instance;
      }
  
      protected MultiTaskListener(Context context) {
          context.put(taskListenerKey, this);
          ccw = ClientCodeWrapper.instance(context);
          dcfh = DeferredCompletionFailureHandler.instance(context);
      }
  
      /**
       * The current set of registered listeners.
       * This is a mutable reference to an immutable array.
       */
      TaskListener[] listeners = EMPTY_LISTENERS;
  
      ClientCodeWrapper ccw;
  
      public Collection<TaskListener> getTaskListeners() {
          return Arrays.asList(listeners);
      }
  
      public boolean isEmpty() {
          return listeners == EMPTY_LISTENERS;
      }
  
      public void add(TaskListener listener) {
          for (TaskListener l: listeners) {
              if (ccw.unwrap(l) == listener)
                  throw new IllegalStateException();
          }
          listeners = Arrays.copyOf(listeners, listeners.length + 1);
          listeners[listeners.length - 1] = ccw.wrap(listener);
      }
  
      public void remove(TaskListener listener) {
          for (int i = 0; i < listeners.length; i++) {
              if (ccw.unwrap(listeners[i]) == listener) {
                  if (listeners.length == 1) {
                      listeners = EMPTY_LISTENERS;
                  } else {
                      TaskListener[] newListeners = new TaskListener[listeners.length - 1];
                      System.arraycopy(listeners, 0, newListeners, 0, i);
                      System.arraycopy(listeners, i + 1, newListeners, i, newListeners.length - i);
                      listeners = newListeners;
                  }
                  break;
              }
          }
      }
  
      @Override @DefinedBy(Api.COMPILER_TREE)
      public void started(TaskEvent e) {
          Handler prevDeferredHandler = dcfh.setHandler(dcfh.userCodeHandler);
          try {
              // guard against listeners being updated by a listener
              TaskListener[] ll = this.listeners;
              for (TaskListener l: ll)
                  l.started(e);
          } finally {
              dcfh.setHandler(prevDeferredHandler);
          }
      }
  
      @Override @DefinedBy(Api.COMPILER_TREE)
      public void finished(TaskEvent e) {
          Handler prevDeferredHandler = dcfh.setHandler(dcfh.userCodeHandler);
          try {
              // guard against listeners being updated by a listener
              TaskListener[] ll = this.listeners;
              for (TaskListener l: ll)
                  l.finished(e);
          } finally {
              dcfh.setHandler(prevDeferredHandler);
          }
      }
  
      @Override
      public String toString() {
          return Arrays.toString(listeners);
      }
  
      public void clear() {
          listeners = EMPTY_LISTENERS;
      }
  }
  