1 files changed, 91 insertions, 0 deletions
diff --git a/bundles/org.eclipse.compare/compare/org/eclipse/compare/internal/ContentChangeNotifier.java b/bundles/org.eclipse.compare/compare/org/eclipse/compare/internal/ContentChangeNotifier.java
new file mode 100644
index 000000000..9aee9c259
--- /dev/null
+++ b/bundles/org.eclipse.compare/compare/org/eclipse/compare/internal/ContentChangeNotifier.java
@@ -0,0 +1,91 @@
+/*******************************************************************************
+ * Copyright (c) 2006, 2010 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.compare.internal;
+
+import org.eclipse.compare.IContentChangeListener;
+import org.eclipse.compare.IContentChangeNotifier;
+import org.eclipse.core.runtime.ISafeRunnable;
+import org.eclipse.core.runtime.ListenerList;
+import org.eclipse.core.runtime.SafeRunner;
+import org.eclipse.swt.widgets.Display;
+
+/**
+ * A helper class for managing content change notification.
+ */
+public class ContentChangeNotifier implements IContentChangeNotifier {
+
+	private ListenerList fListenerList;
+	private final IContentChangeNotifier element;
+	
+	public ContentChangeNotifier(IContentChangeNotifier element) {
+		this.element = element;
+	}
+
+	/* (non-Javadoc)
+	 * see IContentChangeNotifier.addChangeListener
+	 */
+	public void addContentChangeListener(IContentChangeListener listener) {
+		if (fListenerList == null)
+			fListenerList= new ListenerList();
+		fListenerList.add(listener);
+	}
+	
+	/* (non-Javadoc)
+	 * see IContentChangeNotifier.removeChangeListener
+	 */
+	public void removeContentChangeListener(IContentChangeListener listener) {
+		if (fListenerList != null) {
+			fListenerList.remove(listener);
+			if (fListenerList.isEmpty())
+				fListenerList= null;
+		}
+	}
+	
+	/**
+	 * Notifies all registered <code>IContentChangeListener</code>s of a content change.
+	 */
+	public void fireContentChanged() {
+		if (isEmpty()) {
+			return;
+		}
+		// Legacy listeners may expect to be notified in the UI thread.
+		Runnable runnable = new Runnable() {
+			public void run() {
+				Object[] listeners= fListenerList.getListeners();
+				for (int i= 0; i < listeners.length; i++) {
+					final IContentChangeListener contentChangeListener = (IContentChangeListener)listeners[i];
+					SafeRunner.run(new ISafeRunnable() {
+						public void run() throws Exception {
+							contentChangeListener.contentChanged(element);
+						}
+						public void handleException(Throwable exception) {
+							// Logged by safe runner
+						}
+					});
+				}
+			}
+		};
+		if (Display.getCurrent() == null) {
+			Display.getDefault().syncExec(runnable);
+		} else {
+			runnable.run();
+		}
+	}
+
+	/**
+	 * Return whether this notifier is empty (i.e. has no listeners).
+	 * @return whether this notifier is empty 
+	 */
+	public boolean isEmpty() {
+		return fListenerList == null || fListenerList.isEmpty();
+	}
+
+}