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/*******************************************************************************
 * Copyright (c) 2005, 2007 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/

package org.eclipse.jface.action;

import org.eclipse.core.commands.common.EventManager;
import org.eclipse.jface.util.IPropertyChangeListener;
import org.eclipse.jface.util.PropertyChangeEvent;

/**
 * <p>
 * Some common functionality to share between implementations of
 * <code>IAction</code>. This functionality deals with the property change
 * event mechanism.
 * </p>
 * <p>
 * Clients may neither instantiate nor extend this class.
 * </p>
 * 
 * @since 3.2
 */
public abstract class AbstractAction extends EventManager implements IAction {

  public void addPropertyChangeListener(final IPropertyChangeListener listener) {
    addListenerObject(listener);
  }

  /**
   * Notifies any property change listeners that a property has changed. Only
   * listeners registered at the time this method is called are notified.
   * 
   * @param event
   *            the property change event
   * 
   * @see org.eclipse.jface.util.IPropertyChangeListener#propertyChange(PropertyChangeEvent)
   */
  protected final void firePropertyChange(final PropertyChangeEvent event) {
    final Object[] list = getListeners();
    for (int i = 0; i < list.length; ++i) {
      ((IPropertyChangeListener) list[i]).propertyChange(event);
    }
  }

  /**
   * Notifies any property change listeners that a property has changed. Only
   * listeners registered at the time this method is called are notified. This
   * method avoids creating an event object if there are no listeners
   * registered, but calls
   * <code>firePropertyChange(PropertyChangeEvent)</code> if there are.
   * 
   * @param propertyName
   *            the name of the property that has changed
   * @param oldValue
   *            the old value of the property, or <code>null</code> if none
   * @param newValue
   *            the new value of the property, or <code>null</code> if none
   * 
   * @see org.eclipse.jface.util.IPropertyChangeListener#propertyChange(PropertyChangeEvent)
   */
  protected final void firePropertyChange(final String propertyName,
      final Object oldValue, final Object newValue) {
    if (isListenerAttached()) {
      firePropertyChange(new PropertyChangeEvent(this, propertyName,
          oldValue, newValue));
    }
  }

  public void removePropertyChangeListener(
      final IPropertyChangeListener listener) {
    removeListenerObject(listener);
  }

}
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