| /******************************************************************************* |
| * 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.core.internal.variables; |
| |
| |
| /** |
| * Local version of org.eclipse.jface.util.ListenerList (modified)s |
| */ |
| public class ListenerList { |
| /** |
| * The current number of listeners. |
| * Maintains invariant: 0 <= fSize <= listeners.length. |
| */ |
| private int fSize; |
| |
| /** |
| * The list of listeners. Initially <code>null</code> but initialized |
| * to an array of size capacity the first time a listener is added. |
| * Maintains invariant: listeners != null if and only if fSize != 0 |
| */ |
| private Object[] fListeners= null; |
| |
| /** |
| * The empty array singleton instance, returned by getListeners() |
| * when size == 0. |
| */ |
| private static final Object[] EmptyArray= new Object[0]; |
| |
| /** |
| * Creates a listener list with the given initial capacity. |
| * |
| * @param capacity the number of listeners which this list can initially accept |
| * without growing its internal representation; must be at least 1 |
| */ |
| public ListenerList(int capacity) { |
| if (capacity < 1) { |
| throw new IllegalArgumentException(); |
| } |
| fListeners= new Object[capacity]; |
| fSize= 0; |
| } |
| |
| /** |
| * Adds a listener to the list. |
| * Has no effect if an identical listener is already registered. |
| * |
| * @param listener a listener |
| */ |
| public synchronized void add(Object listener) { |
| if (listener == null) { |
| throw new IllegalArgumentException(); |
| } |
| // check for duplicates using identity |
| for (int i= 0; i < fSize; ++i) { |
| if (fListeners[i] == listener) { |
| return; |
| } |
| } |
| // grow array if necessary |
| if (fSize == fListeners.length) { |
| Object[] temp= new Object[(fSize * 2) + 1]; |
| System.arraycopy(fListeners, 0, temp, 0, fSize); |
| fListeners= temp; |
| } |
| fListeners[fSize++]= listener; |
| } |
| |
| /** |
| * Returns an array containing all the registered listeners. |
| * The resulting array is unaffected by subsequent adds or removes. |
| * If there are no listeners registered, the result is an empty array |
| * singleton instance (no garbage is created). |
| * Use this method when notifying listeners, so that any modifications |
| * to the listener list during the notification will have no effect on the |
| * notification itself. |
| */ |
| public synchronized Object[] getListeners() { |
| if (fSize == 0) { |
| return EmptyArray; |
| } |
| Object[] result= new Object[fSize]; |
| System.arraycopy(fListeners, 0, result, 0, fSize); |
| return result; |
| } |
| |
| /** |
| * Removes a listener from the list. |
| * Has no effect if an identical listener was not already registered. |
| * |
| * @param listener a listener |
| */ |
| public synchronized void remove(Object listener) { |
| if (listener == null) { |
| throw new IllegalArgumentException(); |
| } |
| |
| for (int i= 0; i < fSize; ++i) { |
| if (fListeners[i] == listener) { |
| if (--fSize == 0) { |
| fListeners= new Object[1]; |
| } else { |
| if (i < fSize) { |
| fListeners[i]= fListeners[fSize]; |
| } |
| fListeners[fSize]= null; |
| } |
| return; |
| } |
| } |
| } |
| |
| /** |
| * Removes all the listeners from the list. |
| */ |
| public void removeAll() { |
| fListeners= new Object[0]; |
| fSize= 0; |
| } |
| |
| /** |
| * Returns the number of registered listeners |
| * |
| * @return the number of registered listeners |
| */ |
| public int size() { |
| return fSize; |
| } |
| } |
| |