--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/org.eclipse.core.databinding.observable/src/org/eclipse/core/databinding/observable/map/ComputedObservableMap.d	Tue Apr 21 10:55:51 2009 +0200
@@ -0,0 +1,161 @@
+/*******************************************************************************
+ * 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.AbstractSet;
+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.Diffs;
+import org.eclipse.core.databinding.observable.set.IObservableSet;
+import org.eclipse.core.databinding.observable.set.ISetChangeListener;
+import org.eclipse.core.databinding.observable.set.SetChangeEvent;
+
+/**
+ * Maps objects to one of their attributes. Tracks changes to the underlying
+ * observable set of objects (keys), as well as changes to attribute values.
+ */
+public abstract class ComputedObservableMap : AbstractObservableMap {
+
+    private final IObservableSet keySet;
+
+    private ISetChangeListener setChangeListener = new class() ISetChangeListener {
+        public void handleSetChange(SetChangeEvent event) {
+            Set addedKeys = new HashSet(event.diff.getAdditions());
+            Set removedKeys = new HashSet(event.diff.getRemovals());
+            Map oldValues = new HashMap();
+            Map newValues = new HashMap();
+            for (Iterator it = removedKeys.iterator(); it.hasNext();) {
+                Object removedKey = it.next();
+                Object oldValue = doGet(removedKey);
+                unhookListener(removedKey);
+                if (oldValue !is null) {
+                    oldValues.put(removedKey, oldValue);
+                }
+            }
+            for (Iterator it = addedKeys.iterator(); it.hasNext();) {
+                Object addedKey = it.next();
+                hookListener(addedKey);
+                Object newValue = doGet(addedKey);
+                newValues.put(addedKey, newValue);
+            }
+            fireMapChange(Diffs.createMapDiff(addedKeys, removedKeys,
+                    Collections.EMPTY_SET, oldValues, newValues));
+        }
+    };
+
+    private Set entrySet = new EntrySet();
+
+    private class EntrySet : AbstractSet {
+
+        public Iterator iterator() {
+            final Iterator keyIterator = keySet.iterator();
+            return new class() Iterator {
+
+                public bool hasNext() {
+                    return keyIterator.hasNext();
+                }
+
+                public Object next() {
+                    final Object key = keyIterator.next();
+                    return new Map.Entry() {
+
+                        public Object getKey() {
+                            return key;
+                        }
+
+                        public Object getValue() {
+                            return get(getKey());
+                        }
+
+                        public Object setValue(Object value) {
+                            return put(getKey(), value);
+                        }
+                    };
+                }
+
+                public void remove() {
+                    keyIterator.remove();
+                }
+            };
+        }
+
+        public int size() {
+            return keySet.size();
+        }
+
+    }
+
+    /**
+     * @param keySet
+     */
+    public this(IObservableSet keySet) {
+        super(keySet.getRealm());
+        this.keySet = keySet;
+        this.keySet.addSetChangeListener(setChangeListener);
+    }
+
+    protected void init() {
+        for (Iterator it = this.keySet.iterator(); it.hasNext();) {
+            Object key = it.next();
+            hookListener(key);
+        }
+    }
+
+    protected final void fireSingleChange(Object key, Object oldValue,
+            Object newValue) {
+        fireMapChange(Diffs.createMapDiffSingleChange(key, oldValue, newValue));
+    }
+
+    public Set entrySet() {
+        return entrySet;
+    }
+    
+    public Set keySet() {
+        return keySet;
+    }
+
+    final public Object get(Object key) {
+        return doGet(key);
+    }
+
+    final public Object put(Object key, Object value) {
+        return doPut(key, value);
+    }
+
+    /**
+     * @param removedKey
+     */
+    protected abstract void unhookListener(Object removedKey);
+
+    /**
+     * @param addedKey
+     */
+    protected abstract void hookListener(Object addedKey);
+
+    /**
+     * @param key
+     * @return the value for the given key
+     */
+    protected abstract Object doGet(Object key);
+
+    /**
+     * @param key
+     * @param value
+     * @return the old value for the given key
+     */
+    protected abstract Object doPut(Object key, Object value);
+}