--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/org.eclipse.core.commands/src/org/eclipse/core/commands/AbstractHandler.d	Sat Mar 14 18:23:29 2009 +0100
@@ -0,0 +1,172 @@
+/*******************************************************************************
+ * Copyright (c) 2004, 2008 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.AbstractHandler;
+
+import org.eclipse.core.commands.common.EventManager;
+import org.eclipse.core.commands.IHandler2;
+import org.eclipse.core.commands.IHandlerListener;
+import org.eclipse.core.commands.HandlerEvent;
+
+import java.lang.all;
+
+/**
+ * <p>
+ * This class is a partial implementation of <code>IHandler</code>. This
+ * abstract implementation provides support for handler listeners. You should
+ * subclass from this method unless you want to implement your own listener
+ * support. Subclasses should call
+ * {@link AbstractHandler#fireHandlerChanged(HandlerEvent)}when the handler
+ * changes. Subclasses can also override {@link AbstractHandler#isEnabled()} and
+ * {@link AbstractHandler#isHandled()}.
+ * </p>
+ *
+ * @since 3.1
+ */
+public abstract class AbstractHandler : EventManager, IHandler2 {
+
+    /**
+     * Track this base class enabled state.
+     * 
+     * @since 3.4
+     */
+    private bool baseEnabled = true;
+
+    /**
+     * @see IHandler#addHandlerListener(IHandlerListener)
+     */
+    public void addHandlerListener(IHandlerListener handlerListener) {
+        addListenerObject(cast(Object)handlerListener);
+    }
+
+    /**
+     * The default implementation does nothing. Subclasses who attach listeners
+     * to other objects are encouraged to detach them in this method.
+     *
+     * @see org.eclipse.core.commands.IHandler#dispose()
+     */
+    public void dispose() {
+        // Do nothing.
+    }
+
+    /**
+     * Fires an event to all registered listeners describing changes to this
+     * instance.
+     * <p>
+     * Subclasses may extend the definition of this method (i.e., if a different
+     * type of listener can be attached to a subclass). This is used primarily
+     * for support of <code>AbstractHandler</code> in
+     * <code>org.eclipse.ui.workbench</code>, and clients should be wary of
+     * overriding this behaviour. If this method is overridden, then the first
+     * line of the method should be "<code>super.fireHandlerChanged(handlerEvent);</code>".
+     * </p>
+     *
+     * @param handlerEvent
+     *            the event describing changes to this instance. Must not be
+     *            <code>null</code>.
+     */
+    protected void fireHandlerChanged(HandlerEvent handlerEvent) {
+        if (handlerEvent is null) {
+            throw new NullPointerException();
+        }
+
+        Object[] listeners = getListeners();
+        for (int i = 0; i < listeners.length; i++) {
+            IHandlerListener listener = cast(IHandlerListener) listeners[i];
+            listener.handlerChanged(handlerEvent);
+        }
+    }
+
+    /**
+     * Whether this handler is capable of executing at this time. Subclasses may
+     * override this method. If clients override this method they should also
+     * consider overriding {@link #setEnabled(Object)} so they can be notified
+     * about framework execution contexts.
+     *
+     * @return <code>true</code>
+     * @see #setEnabled(Object)
+     * @see #setBaseEnabled(bool)
+     */
+    public bool isEnabled() {
+        return baseEnabled;
+    }
+
+    /**
+     * Allow the default {@link #isEnabled()} to answer our enabled state. It
+     * will fire a HandlerEvent if necessary. If clients use this method they
+     * should also consider overriding {@link #setEnabled(Object)} so they can
+     * be notified about framework execution contexts.
+     * 
+     * @param state
+     *            the enabled state
+     * @since 3.4
+     */
+    protected void setBaseEnabled(bool state) {
+        if (baseEnabled is state) {
+            return;
+        }
+        baseEnabled = state;
+        fireHandlerChanged(new HandlerEvent(this, true, false));
+    }
+
+    /**
+     * Called by the framework to allow the handler to update its enabled state
+     * by extracting the same information available at execution time. Clients
+     * may override if they need to extract information from the application
+     * context.
+     * 
+     * @param evaluationContext
+     *            the application context. May be <code>null</code>
+     * @since 3.4
+     * @see #setBaseEnabled(bool)
+     */
+    public void setEnabled(Object evaluationContext) {
+    }
+
+    /**
+     * Whether this handler is capable of handling delegated responsibilities at
+     * this time. Subclasses may override this method.
+     *
+     * @return <code>true</code>
+     */
+    public bool isHandled() {
+        return true;
+    }
+
+    /**
+     * <p>
+     * Returns true iff there is one or more IHandlerListeners attached to this
+     * AbstractHandler.
+     * </p>
+     * <p>
+     * Subclasses may extend the definition of this method (i.e., if a different
+     * type of listener can be attached to a subclass). This is used primarily
+     * for support of <code>AbstractHandler</code> in
+     * <code>org.eclipse.ui.workbench</code>, and clients should be wary of
+     * overriding this behaviour. If this method is overridden, then the return
+     * value should include "<code>super.hasListeners() ||</code>".
+     * </p>
+     *
+     * @return true iff there is one or more IHandlerListeners attached to this
+     *         AbstractHandler
+     */
+    protected bool hasListeners() {
+        return isListenerAttached();
+    }
+
+    /**
+     * @see IHandler#removeHandlerListener(IHandlerListener)
+     */
+    public void removeHandlerListener(IHandlerListener handlerListener) {
+        removeListenerObject(cast(Object)handlerListener);
+    }
+}