--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/dwtx/core/runtime/ListenerList.d	Wed Mar 26 00:57:19 2008 +0100
@@ -0,0 +1,194 @@
+/*******************************************************************************
+ * Copyright (c) 2004, 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 dwtx.core.runtime.ListenerList;
+
+import dwt.dwthelper.utils;
+
+/**
+ * This class is a thread safe list that is designed for storing lists of listeners.
+ * The implementation is optimized for minimal memory footprint, frequent reads
+ * and infrequent writes.  Modification of the list is synchronized and relatively
+ * expensive, while accessing the listeners is very fast.  Readers are given access
+ * to the underlying array data structure for reading, with the trust that they will
+ * not modify the underlying array.
+ * <p>
+ * <a name="same">A listener list handles the <i>same</i> listener being added
+ * multiple times, and tolerates removal of listeners that are the same as other
+ * listeners in the list.  For this purpose, listeners can be compared with each other
+ * using either equality or identity, as specified in the list constructor.
+ * </p>
+ * <p>
+ * Use the <code>getListeners</code> method when notifying listeners. The recommended
+ * code sequence for notifying all registered listeners of say,
+ * <code>FooListener.eventHappened</code>, is:
+ *
+ * <pre>
+ * Object[] listeners = myListenerList.getListeners();
+ * for (int i = 0; i &lt; listeners.length; ++i) {
+ *  ((FooListener) listeners[i]).eventHappened(event);
+ * }
+ * </pre>
+ *
+ * </p><p>
+ * This class can be used without OSGi running.
+ * </p>
+ * @since dwtx.equinox.common 3.2
+ */
+public class ListenerList {
+
+    /**
+     * The empty array singleton instance.
+     */
+    private static const Object[] EmptyArray;
+
+    /**
+     * Mode constant (value 0) indicating that listeners should be considered
+     * the <a href="#same">same</a> if they are equal.
+     */
+    public static const int EQUALITY = 0;
+
+    /**
+     * Mode constant (value 1) indicating that listeners should be considered
+     * the <a href="#same">same</a> if they are identical.
+     */
+    public static const int IDENTITY = 1;
+
+    /**
+     * Indicates the comparison mode used to determine if two
+     * listeners are equivalent
+     */
+    private final bool identity;
+
+    /**
+     * The list of listeners.  Initially empty but initialized
+     * to an array of size capacity the first time a listener is added.
+     * Maintains invariant: listeners !is null
+     */
+    private Object[] listeners;
+
+    /**
+     * Creates a listener list in which listeners are compared using equality.
+     */
+    public this() {
+        this(EQUALITY);
+    }
+
+    /**
+     * Creates a listener list using the provided comparison mode.
+     *
+     * @param mode The mode used to determine if listeners are the <a href="#same">same</a>.
+     */
+    public this(int mode) {
+        if (mode !is EQUALITY && mode !is IDENTITY)
+            throw new IllegalArgumentException( null );
+        this.identity = mode is IDENTITY;
+    }
+
+    /**
+     * Adds a listener to this list. This method has no effect if the <a href="#same">same</a>
+     * listener is already registered.
+     *
+     * @param listener the non-<code>null</code> listener to add
+     */
+    public synchronized void add(Object listener) {
+        // This method is synchronized to protect against multiple threads adding
+        // or removing listeners concurrently. This does not block concurrent readers.
+        if (listener is null)
+            throw new IllegalArgumentException( null );
+        // check for duplicates
+        final int oldSize = listeners.length;
+        for (int i = 0; i < oldSize; ++i) {
+            Object listener2 = listeners[i];
+            if (identity ? listener is listener2 : listener.opEquals(listener2))
+                return;
+        }
+        // Thread safety: create new array to avoid affecting concurrent readers
+        Object[] newListeners = new Object[oldSize + 1];
+        System.arraycopy(listeners, 0, newListeners, 0, oldSize);
+        newListeners[oldSize] = listener;
+        //atomic assignment
+        this.listeners = newListeners;
+    }
+
+    /**
+     * 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.
+     * 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.
+     * <p>
+     * Note: Callers of this method <b>must not</b> modify the returned array.
+     *
+     * @return the list of registered listeners
+     */
+    public Object[] getListeners() {
+        return listeners;
+    }
+
+    /**
+     * Returns whether this listener list is empty.
+     *
+     * @return <code>true</code> if there are no registered listeners, and
+     *   <code>false</code> otherwise
+     */
+    public bool isEmpty() {
+        return listeners.length is 0;
+    }
+
+    /**
+     * Removes a listener from this list. Has no effect if the <a href="#same">same</a>
+     * listener was not already registered.
+     *
+     * @param listener the non-<code>null</code> listener to remove
+     */
+    public synchronized void remove(Object listener) {
+        // This method is synchronized to protect against multiple threads adding
+        // or removing listeners concurrently. This does not block concurrent readers.
+        if (listener is null)
+            throw new IllegalArgumentException( null );
+        int oldSize = listeners.length;
+        for (int i = 0; i < oldSize; ++i) {
+            Object listener2 = listeners[i];
+            if (identity ? listener is listener2 : listener.opEquals(listener2)) {
+                if (oldSize is 1) {
+                    listeners = EmptyArray;
+                } else {
+                    // Thread safety: create new array to avoid affecting concurrent readers
+                    Object[] newListeners = new Object[oldSize - 1];
+                    System.arraycopy(listeners, 0, newListeners, 0, i);
+                    System.arraycopy(listeners, i + 1, newListeners, i, oldSize - i - 1);
+                    //atomic assignment to field
+                    this.listeners = newListeners;
+                }
+                return;
+            }
+        }
+    }
+
+    /**
+     * Returns the number of registered listeners.
+     *
+     * @return the number of registered listeners
+     */
+    public int size() {
+        return listeners.length;
+    }
+
+    /**
+     * Removes all listeners from this list.
+     */
+    public synchronized void clear() {
+            listeners = EmptyArray;
+    }
+}