1 files changed, 154 insertions, 0 deletions
diff --git a/jpa/plugins/org.eclipse.jpt.ui/src/org/eclipse/jpt/ui/internal/listeners/SWTTreeChangeListenerWrapper.java b/jpa/plugins/org.eclipse.jpt.ui/src/org/eclipse/jpt/ui/internal/listeners/SWTTreeChangeListenerWrapper.java
new file mode 100644
index 0000000000..29462e9c53
--- /dev/null
+++ b/jpa/plugins/org.eclipse.jpt.ui/src/org/eclipse/jpt/ui/internal/listeners/SWTTreeChangeListenerWrapper.java
@@ -0,0 +1,154 @@
+/*******************************************************************************
+ * Copyright (c) 2007, 2010 Oracle. 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:
+ *     Oracle - initial API and implementation
+ ******************************************************************************/
+package org.eclipse.jpt.ui.internal.listeners;
+
+import org.eclipse.jpt.utility.model.event.TreeAddEvent;
+import org.eclipse.jpt.utility.model.event.TreeChangeEvent;
+import org.eclipse.jpt.utility.model.event.TreeClearEvent;
+import org.eclipse.jpt.utility.model.event.TreeRemoveEvent;
+import org.eclipse.jpt.utility.model.listener.TreeChangeListener;
+import org.eclipse.swt.widgets.Display;
+
+/**
+ * Wrap another tree change listener and forward events to it on the SWT
+ * UI thread, asynchronously if necessary. If the event arrived on the UI
+ * thread that is probably because it was initiated by a UI widget; as a
+ * result, we want to loop back synchronously so the events can be
+ * short-circuited.
+ */
+public class SWTTreeChangeListenerWrapper
+	implements TreeChangeListener
+{
+	private final TreeChangeListener listener;
+
+	public SWTTreeChangeListenerWrapper(TreeChangeListener listener) {
+		super();
+		if (listener == null) {
+			throw new NullPointerException();
+		}
+		this.listener = listener;
+	}
+
+	public void nodeAdded(TreeAddEvent event) {
+		if (this.isExecutingOnUIThread()) {
+			this.nodeAdded_(event);
+		} else {
+			this.executeOnUIThread(this.buildNodeAddedRunnable(event));
+		}
+	}
+
+	public void nodeRemoved(TreeRemoveEvent event) {
+		if (this.isExecutingOnUIThread()) {
+			this.nodeRemoved_(event);
+		} else {
+			this.executeOnUIThread(this.buildNodeRemovedRunnable(event));
+		}
+	}
+
+	public void treeCleared(TreeClearEvent event) {
+		if (this.isExecutingOnUIThread()) {
+			this.treeCleared_(event);
+		} else {
+			this.executeOnUIThread(this.buildTreeClearedRunnable(event));
+		}
+	}
+
+	public void treeChanged(TreeChangeEvent event) {
+		if (this.isExecutingOnUIThread()) {
+			this.treeChanged_(event);
+		} else {
+			this.executeOnUIThread(this.buildTreeChangedRunnable(event));
+		}
+	}
+
+	private Runnable buildNodeAddedRunnable(final TreeAddEvent event) {
+		return new Runnable() {
+			public void run() {
+				SWTTreeChangeListenerWrapper.this.nodeAdded_(event);
+			}
+			@Override
+			public String toString() {
+				return "node added"; //$NON-NLS-1$
+			}
+		};
+	}
+
+	private Runnable buildNodeRemovedRunnable(final TreeRemoveEvent event) {
+		return new Runnable() {
+			public void run() {
+				SWTTreeChangeListenerWrapper.this.nodeRemoved_(event);
+			}
+			@Override
+			public String toString() {
+				return "node removed"; //$NON-NLS-1$
+			}
+		};
+	}
+
+	private Runnable buildTreeClearedRunnable(final TreeClearEvent event) {
+		return new Runnable() {
+			public void run() {
+				SWTTreeChangeListenerWrapper.this.treeCleared_(event);
+			}
+			@Override
+			public String toString() {
+				return "tree cleared"; //$NON-NLS-1$
+			}
+		};
+	}
+
+	private Runnable buildTreeChangedRunnable(final TreeChangeEvent event) {
+		return new Runnable() {
+			public void run() {
+				SWTTreeChangeListenerWrapper.this.treeChanged_(event);
+			}
+			@Override
+			public String toString() {
+				return "tree changed"; //$NON-NLS-1$
+			}
+		};
+	}
+
+	private boolean isExecutingOnUIThread() {
+		return Display.getCurrent() != null;
+	}
+
+	/**
+	 * {@link Display#asyncExec(Runnable)} seems to work OK;
+	 * but using {@link Display#syncExec(Runnable)} can somtimes make things
+	 * more predictable when debugging, at the risk of deadlocks.
+	 */
+	private void executeOnUIThread(Runnable r) {
+		Display.getDefault().asyncExec(r);
+//		Display.getDefault().syncExec(r);
+	}
+
+	void nodeAdded_(TreeAddEvent event) {
+		this.listener.nodeAdded(event);
+	}
+
+	void nodeRemoved_(TreeRemoveEvent event) {
+		this.listener.nodeRemoved(event);
+	}
+
+	void treeCleared_(TreeClearEvent event) {
+		this.listener.treeCleared(event);
+	}
+
+	void treeChanged_(TreeChangeEvent event) {
+		this.listener.treeChanged(event);
+	}
+
+	@Override
+	public String toString() {
+		return "SWT(" + this.listener.toString() + ')'; //$NON-NLS-1$
+	}
+
+}