1 files changed, 133 insertions, 0 deletions
diff --git a/extraplugins/layers/org.eclipse.papyrus.layers.runtime/src/org/eclipse/papyrus/layers/runtime/notifier/AbstractDerivedViewLayerNotifier.java b/extraplugins/layers/org.eclipse.papyrus.layers.runtime/src/org/eclipse/papyrus/layers/runtime/notifier/AbstractDerivedViewLayerNotifier.java
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index 00000000000..a71a7afb2c0
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+++ b/extraplugins/layers/org.eclipse.papyrus.layers.runtime/src/org/eclipse/papyrus/layers/runtime/notifier/AbstractDerivedViewLayerNotifier.java
@@ -0,0 +1,133 @@
+/*****************************************************************************
+ * Copyright (c) 2013 Cedric Dumoulin.
+ *
+ *    
+ * 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:
+ *  Cedric Dumoulin  Cedric.dumoulin@lifl.fr - Initial API and implementation
+ *
+ *****************************************************************************/
+
+package org.eclipse.papyrus.layers.runtime.notifier;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import org.eclipse.papyrus.layers.stackmodel.layers.RegExpLayer;
+
+/**
+ * Common ancestor of DerivedViewLayerNotifier.
+ * This class maintains a list of listeners. It allows to add and remove listeners.
+ * If there is no more listener, stop listening on external events.
+ * Start listening on external events as soon as there is a listener.
+ * 
+ * @author cedric dumoulin
+ *
+ */
+public abstract class AbstractDerivedViewLayerNotifier {
+
+	/**
+	 * List of listeners that should be notified.
+	 */
+	protected List<RegExpLayer> listeners = new ArrayList<RegExpLayer>();
+	
+	/**
+	 * Indicate if this Notifier is listening on externals events
+	 */
+	private boolean isListening = false;
+	
+	/**
+	 * Attach the listener to this notifier.
+	 * 
+	 * @param layer
+	 */
+	public void addListener(RegExpLayer listener) {
+		if(!listeners.contains(listener)) {
+			listeners.add(listener);
+			checkStartListening();
+		}
+	}
+	
+	/**
+	 * Attach the listener to this notifier.
+	 * 
+	 * @param layer
+	 */
+	public void removeListener(RegExpLayer listener) {
+			listeners.remove(listener);
+			checkStopListening();
+		
+	}
+	
+	/**
+	 * Attach the listener to this notifier.
+	 * 
+	 * @param layer
+	 */
+	public void removeAllListeners() {
+		isListening = false;
+		listeners.clear();
+		stopListening();
+	}
+	
+	/**
+	 * Check if we should start listening. 
+	 * If the class is not listening on externals events, and there is some listeners, then 
+	 * start listening (call {@link #startListening()} and set {@link #isListening()} to true.
+	 */
+	private void checkStartListening() {
+		if( !isListening() && listeners.size() > 0) {
+			isListening=true;
+			startListening();
+		}
+	}
+
+	/**
+	 * Check if we should stop listening.
+	 * If the class is  listening on externals events, and there is no more listeners, then 
+	 * stop listening (call {@link #stopListening()} and set {@link #isListening()} to false.
+	 */
+	private void checkStopListening() {
+		if(isListening() && listeners.size() == 0) {
+			isListening = false;
+			stopListening();
+		}
+	}
+
+	/**
+	 * fire the event to all registered listeners.
+	 */
+	public void fireEvent( ) {
+		for( RegExpLayer listener : listeners) {
+//			listener.evaluateExpr();
+		}
+	}
+	
+	/**
+	 * Start listening on external events.
+	 * Should be implemented by subclass
+	 */
+	abstract protected void startListening();
+	
+	/**
+	 * Stop listening on external events.
+	 * Should be implemented by subclass
+	 */
+	abstract protected void stopListening();
+
+	/**
+	 * Return true if this Notifier is listening on externals events.
+	 * @return
+	 */
+	public boolean isListening() {
+		// This notifier is listening if there is some listener in the list
+		return isListening;
+	}
+
+	
+
+}