--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/org.eclipse.jface.databinding/src/org/eclipse/jface/internal/databinding/viewers/SelectionProviderSingleSelectionObservableValue.d	Tue Apr 14 11:35:29 2009 +0200
@@ -0,0 +1,149 @@
+/*******************************************************************************
+ * Copyright (c) 2005, 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
+ *     Brad Reynolds - bug 137877
+ *     Brad Reynolds - bug 164653
+ *     Brad Reynolds - bug 147515
+ *     Ashley Cambrell - bug 198906
+ *******************************************************************************/
+
+module org.eclipse.jface.internal.databinding.viewers.SelectionProviderSingleSelectionObservableValue;
+
+import java.lang.all;
+
+import org.eclipse.core.databinding.observable.Diffs;
+import org.eclipse.core.databinding.observable.Realm;
+import org.eclipse.core.databinding.observable.value.AbstractObservableValue;
+import org.eclipse.jface.util.Util;
+import org.eclipse.jface.viewers.ISelection;
+import org.eclipse.jface.viewers.ISelectionChangedListener;
+import org.eclipse.jface.viewers.ISelectionProvider;
+import org.eclipse.jface.viewers.IStructuredSelection;
+import org.eclipse.jface.viewers.SelectionChangedEvent;
+import org.eclipse.jface.viewers.StructuredSelection;
+
+/**
+ * Observes single selection of an <code>ISelectionProvider</code>.
+ *
+ * @since 1.1
+ */
+public class SelectionProviderSingleSelectionObservableValue :
+        AbstractObservableValue {
+
+    private final ISelectionProvider selectionProvider;
+
+    private bool updating = false;
+
+    private Object currentSelection;
+
+    private ISelectionChangedListener selectionChangedListener;
+
+    /**
+     * Constructs a new instance associated with the provided
+     * <code>selectionProvider</code>. In order to initialize itself properly
+     * the constructor invokes {@link #doGetValue()}. This could be dangerous
+     * for subclasses, see {@link #doGetValue()} for an explanation.
+     *
+     * @param realm
+     *
+     * @param selectionProvider
+     * @see #doGetValue()
+     */
+    public this(Realm realm,
+            ISelectionProvider selectionProvider) {
+        super(realm);
+        if (selectionProvider is null) {
+            throw new IllegalArgumentException(
+                    "The 'selectionProvider' parameter is null."); //$NON-NLS-1$
+        }
+
+        this.selectionProvider = selectionProvider;
+        this.currentSelection = doGetValue();
+
+        selectionChangedListener = new class() ISelectionChangedListener {
+            public void selectionChanged(SelectionChangedEvent event) {
+                if (!updating) {
+                    Object oldSelection = currentSelection;
+                    currentSelection = doGetValue();
+                    fireValueChange(Diffs.createValueDiff(oldSelection,
+                            currentSelection));
+                }
+            }
+        };
+        selectionProvider.addSelectionChangedListener(selectionChangedListener);
+    }
+
+    /**
+     * Sets the selection to the provided <code>value</code>. Value change
+     * events are fired after selection is set in the selection provider.
+     *
+     * @param value
+     *            object to set as selected, <code>null</code> if wanting to
+     *            remove selection
+     */
+    public void doSetValue(Object value) {
+        try {
+            updating = true;
+
+            Object oldSelection = currentSelection;
+            selectionProvider
+                    .setSelection(value is null ? StructuredSelection.EMPTY
+                            : new StructuredSelection(value));
+            currentSelection = doGetValue();
+            if (!Util.equals(oldSelection, currentSelection)) {
+                fireValueChange(Diffs.createValueDiff(oldSelection,
+                        currentSelection));
+            }
+        } finally {
+            updating = false;
+        }
+    }
+
+    /**
+     * Retrieves the current selection.
+     * <p>
+     * If a subclass overrides this method it must not depend upon the subclass
+     * to have been fully initialized before this method is invoked.
+     * <code>doGetValue()</code> is invoked by the
+     * {@link #SelectionProviderSingleSelectionObservableValue(Realm, ISelectionProvider) constructor}
+     * which means the subclass's constructor will not have fully executed
+     * before this method is invoked.
+     * </p>
+     *
+     * @return selection will be an instance of
+     *         <code>IStructuredSelection</code> if a selection exists,
+     *         <code>null</code> if no selection
+     * @see #SelectionProviderSingleSelectionObservableValue(Realm,
+     *      ISelectionProvider)
+     */
+    protected Object doGetValue() {
+        ISelection selection = selectionProvider.getSelection();
+        if (null !is cast(IStructuredSelection)selection) {
+            IStructuredSelection sel = cast(IStructuredSelection) selection;
+            return sel.getFirstElement();
+        }
+
+        return null;
+    }
+
+    public Object getValueType() {
+        return null;
+    }
+
+    /*
+     * (non-Javadoc)
+     *
+     * @see org.eclipse.core.databinding.observable.value.AbstractObservableValue#dispose()
+     */
+    public synchronized void dispose() {
+        selectionProvider
+                .removeSelectionChangedListener(selectionChangedListener);
+        super.dispose();
+    }
+}