--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/org.eclipse.jface.databinding/src/org/eclipse/jface/internal/databinding/provisional/swt/MenuUpdater.d	Tue Apr 14 11:35:29 2009 +0200
@@ -0,0 +1,168 @@
+/*******************************************************************************
+ * Copyright (c) 2006, 2007 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
+ *******************************************************************************/
+module org.eclipse.jface.internal.databinding.provisional.swt.MenuUpdater;
+
+import java.lang.all;
+
+import org.eclipse.core.databinding.observable.ChangeEvent;
+import org.eclipse.core.databinding.observable.IChangeListener;
+import org.eclipse.core.databinding.observable.IObservable;
+import org.eclipse.core.databinding.observable.ObservableTracker;
+import org.eclipse.swt.events.DisposeEvent;
+import org.eclipse.swt.events.DisposeListener;
+import org.eclipse.swt.events.MenuEvent;
+import org.eclipse.swt.events.MenuListener;
+import org.eclipse.swt.widgets.Menu;
+
+/**
+ * NON-API - A MenuUpdater updates an SWT menu in response to changes in the model. By
+ * wrapping a block of code in a MenuUpdater, clients can rely on the fact that
+ * the block of code will be re-executed whenever anything changes in the model
+ * that might affect its behavior.
+ * 
+ * <p>
+ * MenuUpdaters only execute once their menus are shown. If something changes in
+ * the model, the updater is flagged as dirty and it stops listening to the
+ * model until the next time the menu is shown. If the menu is visible while the
+ * model changes, it will be updated right away.
+ * </p>
+ * 
+ * <p>
+ * Clients should subclass this when copying information from the model to a
+ * menu. Typical usage:
+ * </p>
+ * 
+ * <ul>
+ * <li>Override updateMenu. It should do whatever is necessary to display the
+ * contents of the model in the menu.</li>
+ * <li>In the constructor, attach listeners to the model. The listeners should
+ * call markDirty whenever anything changes in the model that affects
+ * updateMenu. Note: this step can be omitted when calling any method tagged
+ * with "@TrackedGetter" since MenuUpdater will automatically attach a listener
+ * to any object if a "@TrackedGetter" method is called in updateMenu.</li>
+ * <li>(optional)Extend dispose() to remove any listeners attached in the
+ * constructor</li>
+ * </ul>
+ * 
+ * @since 1.1
+ */
+public abstract class MenuUpdater {
+    
+    private class PrivateInterface : MenuListener, 
+        DisposeListener, Runnable, IChangeListener {
+
+        // DisposeListener implementation
+        public void widgetDisposed(DisposeEvent e) {
+            this.outer.dispose();
+        }
+        
+        // Runnable implementation. This method runs at most once per repaint whenever the
+        // value gets marked as dirty.
+        public void run() {
+            if (theMenu !is null && !theMenu.isDisposed() && theMenu.isVisible()) {
+                updateIfNecessary();
+            }
+        }
+        
+        // IChangeListener implementation (listening to the ComputedValue)
+        public void handleChange(ChangeEvent event) {
+            // Whenever this updator becomes dirty, schedule the run() method 
+            makeDirty();
+        }
+
+        public void menuHidden(MenuEvent e) {
+            // do nothing
+        }
+
+        public void menuShown(MenuEvent e) {
+            updateIfNecessary();
+        }
+        
+    }
+    
+    private Runnable updateRunnable = new class() Runnable {
+        public void run() {
+            updateMenu();
+        }
+    };
+    
+    private PrivateInterface privateInterface = new PrivateInterface();
+    private Menu theMenu;
+    private IObservable[] dependencies = new IObservable[0];
+    private bool dirty = false;
+    
+    /**
+     * Creates an updator for the given menu.  
+     * 
+     * @param toUpdate menu to update
+     */
+    public this(Menu toUpdate) {
+        theMenu = toUpdate;
+        
+        theMenu.addDisposeListener(privateInterface);
+        theMenu.addMenuListener(privateInterface);
+        makeDirty();
+    }
+    
+    private void updateIfNecessary() {
+        if (dirty) {
+            dependencies = ObservableTracker.runAndMonitor(updateRunnable, privateInterface, null);
+            dirty = false;
+        }
+    }
+
+    /**
+     * This is called automatically when the menu is disposed. It may also
+     * be called explicitly to remove this updator from the menu. Subclasses
+     * will normally extend this method to detach any listeners they attached
+     * in their constructor.
+     */
+    public void dispose() {
+        theMenu.removeDisposeListener(privateInterface);
+        theMenu.removeMenuListener(privateInterface);
+
+        stopListening();
+    }
+
+    private void stopListening() {
+        // Stop listening for dependency changes
+        for (int i = 0; i < dependencies.length; i++) {
+            IObservable observable = dependencies[i];
+                
+            observable.removeChangeListener(privateInterface);
+        }
+    }
+
+    /**
+     * Updates the menu. This method will be invoked once after the
+     * updater is created, and once for any SWT.Show event if this 
+     * updater is marked as dirty at that time.
+     *  
+     * <p>
+     * Subclasses should overload this method to provide any code that 
+     * udates the menu.
+     * </p>
+     */
+    protected abstract void updateMenu();
+    
+    /**
+     * Marks this updator as dirty. Causes the updateControl method to
+     * be invoked before the next time the control is repainted.
+     */
+    protected final void makeDirty() {
+        if (!dirty) {
+            dirty = true;
+            stopListening();
+            SWTUtil.runOnce(theMenu.getDisplay(), privateInterface);
+        }
+    }
+    
+}