EventTable.java

/*******************************************************************************
 * Copyright (c) 2000, 2008, 2012 IBM Corporation, Gerhardt Informatics Kft. 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
 *     Gerhardt Informatics Kft. - GEFGWT port
 *******************************************************************************/
package org.eclipse.swt.widgets;

import org.eclipse.swt.SWT;
import org.eclipse.swt.events.SWTEventListener;

/**
 * Instances of this class implement a simple look up mechanism that maps an
 * event type to a listener. Multiple listeners for the same event type are
 * supported.
 */

class EventTable {
	int[] types;
	Listener[] listeners;
	int level;
	static final int GROW_SIZE = 4;

	public Listener[] getListeners(int eventType) {
		if (types == null)
			return new Listener[0];
		int count = 0;
		for (int i = 0; i < types.length; i++) {
			if (types[i] == eventType)
				count++;
		}
		if (count == 0)
			return new Listener[0];
		Listener[] result = new Listener[count];
		count = 0;
		for (int i = 0; i < types.length; i++) {
			if (types[i] == eventType) {
				result[count++] = listeners[i];
			}
		}
		return result;
	}

	public void hook(int eventType, Listener listener) {
		if (types == null)
			types = new int[GROW_SIZE];
		if (listeners == null)
			listeners = new Listener[GROW_SIZE];
		int length = types.length, index = length - 1;
		while (index >= 0) {
			if (types[index] != 0)
				break;
			--index;
		}
		index++;
		if (index == length) {
			int[] newTypes = new int[length + GROW_SIZE];
			System.arraycopy(types, 0, newTypes, 0, length);
			types = newTypes;
			Listener[] newListeners = new Listener[length + GROW_SIZE];
			System.arraycopy(listeners, 0, newListeners, 0, length);
			listeners = newListeners;
		}
		types[index] = eventType;
		listeners[index] = listener;
	}

	public boolean hooks(int eventType) {
		if (types == null)
			return false;
		for (int i = 0; i < types.length; i++) {
			if (types[i] == eventType)
				return true;
		}
		return false;
	}

	public void sendEvent(Event event) {
		if (types == null)
			return;
		level += level >= 0 ? 1 : -1;
		try {
			for (int i = 0; i < types.length; i++) {
				if (event.type == SWT.None)
					return;
				if (types[i] == event.type) {
					Listener listener = listeners[i];
					if (listener != null)
						listener.handleEvent(event);
				}
			}
		} finally {
			boolean compact = level < 0;
			level -= level >= 0 ? 1 : -1;
			if (compact && level == 0) {
				int index = 0;
				for (int i = 0; i < types.length; i++) {
					if (types[i] != 0) {
						types[index] = types[i];
						listeners[index] = listeners[i];
						index++;
					}
				}
				for (int i = index; i < types.length; i++) {
					types[i] = 0;
					listeners[i] = null;
				}
			}
		}
	}

	public int size() {
		if (types == null)
			return 0;
		int count = 0;
		for (int i = 0; i < types.length; i++) {
			if (types[i] != 0)
				count++;
		}
		return count;
	}

	void remove(int index) {
		if (level == 0) {
			int end = types.length - 1;
			System.arraycopy(types, index + 1, types, index, end - index);
			System.arraycopy(listeners, index + 1, listeners, index, end
					- index);
			index = end;
		} else {
			if (level > 0)
				level = -level;
		}
		types[index] = 0;
		listeners[index] = null;
	}

	public void unhook(int eventType, Listener listener) {
		if (types == null)
			return;
		for (int i = 0; i < types.length; i++) {
			if (types[i] == eventType && listeners[i] == listener) {
				remove(i);
				return;
			}
		}
	}

	public void unhook(int eventType, SWTEventListener listener) {
		if (types == null)
			return;
		for (int i = 0; i < types.length; i++) {
			if (types[i] == eventType) {
				if (listeners[i] instanceof TypedListener) {
					TypedListener typedListener = (TypedListener) listeners[i];
					if (typedListener.getEventListener() == listener) {
						remove(i);
						return;
					}
				}
			}
		}
	}

}