bundles/org.eclipse.ui.workbench/Eclipse UI/org/eclipse/ui/internal/keys/OutOfOrderVerifyListener.java

/*******************************************************************************
 * Copyright (c) 2000, 2003 IBM Corporation and others. All rights reserved.
 * This program and the accompanying materials are made available under the
 * terms of the Common Public License v1.0 which accompanies this distribution,
 * and is available at http://www.eclipse.org/legal/cpl-v10.html
 * 
 * Contributors: IBM Corporation - initial API and implementation
 ******************************************************************************/

package org.eclipse.ui.internal.keys;

import org.eclipse.swt.SWT;
import org.eclipse.swt.custom.StyledText;
import org.eclipse.swt.custom.VerifyKeyListener;
import org.eclipse.swt.events.VerifyEvent;
import org.eclipse.swt.widgets.Widget;

/**
 * A listener that makes sure that out-of-order processing occurs if no other
 * verify listeners do any work.
 * 
 * @since 3.0
 */
class OutOfOrderVerifyListener implements VerifyKeyListener {

	/**
	 * The listener that will be chained in if the verify event has not been
	 * eaten yet.
	 */
	private OutOfOrderListener chainedListener;

	/**
	 * Constructs a new instance of <code>OutOfOrderVerifyListener</code>
	 * with the listener that will be chained in.
	 * 
	 * @param outOfOrderListener
	 *            The listener that should be attached to the widget if the
	 *            verify event is not eaten; must not be <code>null</code>.
	 */
	OutOfOrderVerifyListener(OutOfOrderListener outOfOrderListener) {
		chainedListener = outOfOrderListener;
	}

	/**
	 * Checks whether any other verify listeners have triggered. If not, then
	 * it sets up the top-level out-of-order listener.
	 * 
	 * @param event
	 *            The verify event after it has been processed by all other
	 *            verify listeners; must not be <code>null</code>.
	 */
	public void verifyKey(VerifyEvent event) {
		// Always remove myself as a listener.
		Widget widget = event.widget;
		if (widget instanceof StyledText) {
			((StyledText) widget).removeVerifyKeyListener(this);
		}

		// If the event is still up for grabs, then re-route through
		// the global key filter.
		if (event.doit) {
		    widget.addListener(SWT.Modify, new CancelOnModifyListener(chainedListener));
			widget.addListener(SWT.KeyDown, chainedListener);
		}
	}
}