--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/org.eclipse.core.commands/src/org/eclipse/core/commands/common/EventManager.d	Sat Mar 14 18:23:29 2009 +0100
@@ -0,0 +1,108 @@
+/*******************************************************************************
+ * Copyright (c) 2005, 2006 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
+ * Port to the D programming language:
+ *     Frank Benoit <benoit@tionex.de>
+ *******************************************************************************/
+
+module org.eclipse.core.commands.common.EventManager;
+
+import org.eclipse.core.runtime.ListenerList;
+
+/**
+ * <p>
+ * A manager to which listeners can be attached. This handles the management of
+ * a list of listeners -- optimizing memory and performance. All the methods on
+ * this class are guaranteed to be thread-safe.
+ * </p>
+ * <p>
+ * Clients may extend.
+ * </p>
+ *
+ * @since 3.2
+ */
+public abstract class EventManager {
+
+    /**
+     * An empty array that can be returned from a call to
+     * {@link #getListeners()} when {@link #listenerList} is <code>null</code>.
+     */
+    private static const Object[] EMPTY_ARRAY = null;
+
+    /**
+     * A collection of objects listening to changes to this manager. This
+     * collection is <code>null</code> if there are no listeners.
+     */
+    private /+transient+/ ListenerList listenerList = null;
+
+    /**
+     * Adds a listener to this manager that will be notified when this manager's
+     * state changes.
+     *
+     * @param listener
+     *            The listener to be added; must not be <code>null</code>.
+     */
+    protected synchronized final void addListenerObject(Object listener) {
+        if (listenerList is null) {
+            listenerList = new ListenerList(ListenerList.IDENTITY);
+        }
+
+        listenerList.add(listener);
+    }
+
+    /**
+     * Clears all of the listeners from the listener list.
+     */
+    protected synchronized final void clearListeners() {
+        if (listenerList !is null) {
+            listenerList.clear();
+        }
+    }
+
+    /**
+     * Returns the listeners attached to this event manager.
+     *
+     * @return The listeners currently attached; may be empty, but never
+     *         <code>null</code>
+     */
+    protected final Object[] getListeners() {
+        ListenerList list = listenerList;
+        if (list is null) {
+            return EMPTY_ARRAY;
+        }
+
+        return list.getListeners();
+    }
+
+    /**
+     * Whether one or more listeners are attached to the manager.
+     *
+     * @return <code>true</code> if listeners are attached to the manager;
+     *         <code>false</code> otherwise.
+     */
+    protected final bool isListenerAttached() {
+        return listenerList !is null;
+    }
+
+    /**
+     * Removes a listener from this manager.
+     *
+     * @param listener
+     *            The listener to be removed; must not be <code>null</code>.
+     */
+    protected synchronized final void removeListenerObject(Object listener) {
+        if (listenerList !is null) {
+            listenerList.remove(listener);
+
+            if (listenerList.isEmpty()) {
+                listenerList = null;
+            }
+        }
+    }
+}