--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/org.eclipse.core.databinding.observable/src/org/eclipse/core/databinding/observable/map/BidirectionalMap.d	Tue Apr 21 10:55:51 2009 +0200
@@ -0,0 +1,104 @@
+/*******************************************************************************
+ * 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
+ *******************************************************************************/
+package org.eclipse.core.databinding.observable.map;
+
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.Iterator;
+import java.util.Map;
+import java.util.Set;
+
+import org.eclipse.core.databinding.observable.Realm;
+
+/**
+ * 
+ * <p>
+ * This class is thread safe. All state accessing methods must be invoked from
+ * the {@link Realm#isCurrent() current realm}. Methods for adding and removing
+ * listeners may be invoked from any thread.
+ * </p>
+ * @since 1.0
+ * 
+ */
+public class BidirectionalMap : ObservableMap {
+
+    private Map valueToElements = new HashMap();
+
+    private IMapChangeListener mapListener = new class() IMapChangeListener {
+
+        public void handleMapChange(MapChangeEvent event) {
+            MapDiff diff = event.diff;
+            for (Iterator it = diff.getAddedKeys().iterator(); it.hasNext();) {
+                Object addedKey = it.next();
+                addMapping(addedKey, diff.getNewValue(addedKey));
+            }
+            for (Iterator it = diff.getChangedKeys().iterator(); it.hasNext();) {
+                Object changedKey = it.next();
+                removeMapping(changedKey, diff.getOldValue(changedKey));
+                addMapping(changedKey, diff.getNewValue(changedKey));
+            }
+            for (Iterator it = diff.getRemovedKeys().iterator(); it.hasNext();) {
+                Object removedKey = it.next();
+                removeMapping(removedKey, diff.getOldValue(removedKey));
+            }
+            fireMapChange(diff);
+        }
+    };
+
+    /**
+     * @param wrappedMap
+     */
+    public this(IObservableMap wrappedMap) {
+        super(wrappedMap.getRealm(), wrappedMap);
+        wrappedMap.addMapChangeListener(mapListener);
+        for (Iterator it = wrappedMap.entrySet().iterator(); it.hasNext();) {
+            Map.Entry entry = cast(Entry) it.next();
+            addMapping(entry.getKey(), entry.getValue());
+        }
+    }
+
+    /**
+     * @param key
+     * @param value
+     */
+    private void addMapping(Object key, Object value) {
+        Object elementOrSet = valueToElements.get(value);
+        if (elementOrSet is null) {
+            valueToElements.put(value, key);
+            return;
+        }
+        if (!( null !is cast(Set)elementOrSet )) {
+            elementOrSet = new HashSet(Collections.singleton(elementOrSet));
+            valueToElements.put(value, elementOrSet);
+        }
+        Set set = cast(Set) elementOrSet;
+        set.add(key);
+    }
+
+    /**
+     * @param functionValue
+     * @param element
+     */
+    private void removeMapping(Object functionValue, Object element) {
+        Object elementOrSet = valueToElements.get(functionValue);
+        if ( null !is cast(Set)elementOrSet ) {
+            Set set = cast(Set) elementOrSet;
+            set.remove(element);
+            if (set.size() is 0) {
+                valueToElements.remove(functionValue);
+            }
+        } else {
+            valueToElements.remove(functionValue);
+        }
+    }
+
+}