content: /*
   * Created on Mar 22, 2008
   * 
   * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with
   * the License. You may obtain a copy of the License at
   * 
   * http://www.apache.org/licenses/LICENSE-2.0
   * 
   * Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on
   * an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the
   * specific language governing permissions and limitations under the License.
   * 
   * Copyright @2008-2013 the original author or authors.
   */
  package org.fest.swing.monitor;
  
  import static org.fest.util.Maps.newWeakHashMap;
  import static org.fest.util.Sets.newHashSet;
  
  import java.awt.Component;
  import java.awt.EventQueue;
  import java.lang.ref.WeakReference;
  import java.util.Collection;
  import java.util.Map;
  import java.util.Set;
  
  import javax.annotation.Nonnull;
  import javax.annotation.Nullable;
  
  import org.fest.swing.annotation.RunsInCurrentThread;
  
  /**
   * A mapping of AWT or Swing {@code Component}s, and their respective {@link EventQueue}.
   *
   * @author Yvonne Wang
   * @author Alex Ruiz
   */
  class EventQueueMapping {
    final Map<Component, WeakReference<EventQueue>> queueMap = newWeakHashMap();
  
    @RunsInCurrentThread
    void addQueueFor(@Nonnull Component c) {
      EventQueue queue = c.getToolkit().getSystemEventQueue();
      queueMap.put(c, new WeakReference<EventQueue>(queue));
    }
  
    @RunsInCurrentThread
    @Nullable EventQueue queueFor(@Nonnull Component c) {
      EventQueue queue = storedQueueFor(c);
      if (queue == null) {
        return c.getToolkit().getSystemEventQueue();
      }
      return queue;
    }
  
    @Nullable EventQueue storedQueueFor(@Nonnull Component c) {
      return queueFrom(queueMap.get(c));
    }
  
    @Nonnull Collection<EventQueue> eventQueues() {
      Set<EventQueue> eventQueues = newHashSet();
      for (WeakReference<EventQueue> reference : queueMap.values()) {
        EventQueue queue = queueFrom(reference);
        if (queue != null) {
          eventQueues.add(queue);
        }
      }
      return eventQueues;
    }
  
    private @Nullable EventQueue queueFrom(@Nullable WeakReference<EventQueue> reference) {
      if (reference == null) {
        return null;
      }
      return reference.get();
    }
  }
  