LegacyHandlerWrapper.java :  » IDE-Eclipse » ui-workbench » org » eclipse » ui » internal » handlers » Java Open Source

/*******************************************************************************
 * Copyright (c) 2005 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.ui.internal.handlers;

import org.eclipse.core.commands.ExecutionEvent;
import org.eclipse.core.commands.ExecutionException;
import org.eclipse.core.commands.IHandler;
import org.eclipse.core.commands.IHandlerListener;
import org.eclipse.core.commands.util.Tracing;
import org.eclipse.ui.internal.commands.ILegacyAttributeNames;
import org.eclipse.ui.internal.misc.Policy;

/**
 * A handler that wraps a legacy handler. This provide backward compatibility
 * with the handlers release in Eclipse 3.0.
 * 
 * @since 3.1
 */
public final class LegacyHandlerWrapper implements IHandler {

  /**
   * This flag can be set to <code>true</code> if commands should print
   * information to <code>System.out</code> when changing handlers.
   */
  private static final boolean DEBUG_HANDLERS = Policy.DEBUG_HANDLERS
      && Policy.DEBUG_HANDLERS_VERBOSE;

  /**
   * The wrapped handler; never <code>null</code>.
   */
  private final org.eclipse.ui.commands.IHandler handler;

  /**
   * Constructs a new instance of <code>HandlerWrapper</code>.
   * 
   * @param handler
   *            The handler that should be wrapped; must not be
   *            <code>null</code>.
   */
  public LegacyHandlerWrapper(final org.eclipse.ui.commands.IHandler handler) {
    if (handler == null) {
      throw new NullPointerException(
          "A handler wrapper cannot be constructed on a null handler"); //$NON-NLS-1$
    }

    this.handler = handler;
  }

  /*
   * (non-Javadoc)
   * 
   * @see org.eclipse.core.commands.IHandler#addHandlerListener(org.eclipse.core.commands.IHandlerListener)
   */
  public final void addHandlerListener(final IHandlerListener handlerListener) {
    handler.addHandlerListener(new LegacyHandlerListenerWrapper(this,
        handlerListener));
  }

  /*
   * (non-Javadoc)
   * 
   * @see org.eclipse.core.commands.IHandler#dispose()
   */
  public final void dispose() {
    handler.dispose();
  }

  public final boolean equals(final Object object) {
    if (object instanceof org.eclipse.ui.commands.IHandler) {
      return this.handler == object;
    }

    if (object instanceof LegacyHandlerWrapper) {
      return this.handler == ((LegacyHandlerWrapper) object).handler;
    }

    return false;
  }

  /*
   * (non-Javadoc)
   * 
   * @see org.eclipse.core.commands.IHandler#execute(org.eclipse.core.commands.ExecutionEvent)
   */
  public final Object execute(final ExecutionEvent event)
      throws ExecutionException {
    // Debugging output
    if (DEBUG_HANDLERS) {
      final StringBuffer buffer = new StringBuffer("Executing LegacyHandlerWrapper for "); //$NON-NLS-1$
      if (handler == null) {
        buffer.append("no handler"); //$NON-NLS-1$
      } else {
        buffer.append('\'');
        buffer.append(handler.getClass().getName());
        buffer.append('\'');
      }
      Tracing.printTrace("HANDLERS", buffer.toString()); //$NON-NLS-1$
    }

    try {
      return handler.execute(event.getParameters());
    } catch (final org.eclipse.ui.commands.ExecutionException e) {
      throw new ExecutionException(e.getMessage(), e.getCause());
    }
  }

  public final int hashCode() {
    return this.handler.hashCode();
  }

  public final boolean isEnabled() {
    final Object enabled = handler.getAttributeValuesByName().get(
        ILegacyAttributeNames.ENABLED);
    if (enabled instanceof Boolean) {
      return ((Boolean) enabled).booleanValue();
    }

    return true;
  }

  public final boolean isHandled() {
    final Object handled = handler.getAttributeValuesByName().get(
        ILegacyAttributeNames.HANDLED);
    if (handled instanceof Boolean) {
      return ((Boolean) handled).booleanValue();
    }

    return true;
  }

  public final void removeHandlerListener(
      final IHandlerListener handlerListener) {
    handler.removeHandlerListener(new LegacyHandlerListenerWrapper(this,
        handlerListener));
  }

  public final String toString() {
    final StringBuffer buffer = new StringBuffer();

    buffer.append("LegacyHandlerWrapper("); //$NON-NLS-1$
    buffer.append(handler);
    buffer.append(')');

    return buffer.toString();
  }
}