--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/org.eclipse.core.databinding/src/org/eclipse/core/internal/databinding/observable/StalenessTracker.d	Tue Apr 14 11:35:29 2009 +0200
@@ -0,0 +1,129 @@
+/*******************************************************************************
+ * Copyright (c) 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
+ ******************************************************************************/
+
+module org.eclipse.core.internal.databinding.observable.StalenessTracker;
+
+import java.lang.all;
+
+import java.util.HashMap;
+import java.util.Map;
+
+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.IStaleListener;
+import org.eclipse.core.databinding.observable.StaleEvent;
+import org.eclipse.core.internal.databinding.IdentityWrapper;
+
+/**
+ * @since 1.0
+ * 
+ */
+public class StalenessTracker {
+
+    private Map staleMap = new HashMap();
+
+    private int staleCount = 0;
+
+    private final IStalenessConsumer stalenessConsumer;
+
+    private class ChildListener : IStaleListener, IChangeListener {
+        public void handleStale(StaleEvent event) {
+            processStalenessChange(cast(IObservable) event.getSource(), true);
+        }
+
+        public void handleChange(ChangeEvent event) {
+            processStalenessChange(cast(IObservable) event.getSource(), true);
+        }
+    }
+
+    private ChildListener childListener = new ChildListener();
+
+    /**
+     * @param observables
+     * @param stalenessConsumer 
+     */
+    public this(IObservable[] observables,
+            IStalenessConsumer stalenessConsumer) {
+        this.stalenessConsumer = stalenessConsumer;
+        for (int i = 0; i < observables.length; i++) {
+            IObservable observable = observables[i];
+            doAddObservable(observable, false);
+        }
+        stalenessConsumer.setStale(staleCount > 0);
+    }
+
+    /**
+     * @param child
+     * @param callback
+     */
+    public void processStalenessChange(IObservable child, bool callback) {
+        bool oldStale = staleCount > 0;
+        IdentityWrapper wrappedChild = new IdentityWrapper(child);
+        bool oldChildStale = getOldChildStale(wrappedChild);
+        bool newChildStale = child.isStale();
+        if (oldChildStale !is newChildStale) {
+            if (oldChildStale) {
+                staleCount--;
+            } else {
+                staleCount++;
+            }
+            staleMap.put(wrappedChild, newChildStale ? Boolean.TRUE : Boolean.FALSE);
+        }
+        bool newStale = staleCount > 0;
+        if (callback && (newStale !is oldStale)) {
+            stalenessConsumer.setStale(newStale);
+        }
+    }
+
+    /**
+     * @param wrappedChild
+     */
+    private bool getOldChildStale(IdentityWrapper wrappedChild) {
+        Object oldChildValue = staleMap.get(wrappedChild);
+        bool oldChildStale = oldChildValue is null ? false
+                : (cast(Boolean) oldChildValue).booleanValue();
+        return oldChildStale;
+    }
+
+    /**
+     * @param observable
+     */
+    public void addObservable(IObservable observable) {
+        doAddObservable(observable, true);
+    }
+
+    private void doAddObservable(IObservable observable, bool callback) {
+        processStalenessChange(observable, callback);
+        observable.addChangeListener(childListener);
+        observable.addStaleListener(childListener);
+    }
+
+    /**
+     * @param observable
+     */
+    public void removeObservable(IObservable observable) {
+        bool oldStale = staleCount > 0;
+        IdentityWrapper wrappedChild = new IdentityWrapper(observable);
+        bool oldChildStale = getOldChildStale(wrappedChild);
+        if (oldChildStale) {
+            staleCount--;
+        }
+        staleMap.remove(wrappedChild);
+        observable.removeChangeListener(childListener);
+        observable.removeStaleListener(childListener);
+        bool newStale = staleCount > 0;
+        if (newStale !is oldStale) {
+            stalenessConsumer.setStale(newStale);
+        }
+    }
+
+}