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/*******************************************************************************
* Copyright (c) 2010-2013, Abel Hegedus, Istvan Rath and Daniel Varro
* This program and the accompanying materials are made available under the
* terms of the Eclipse Public License v. 2.0 which is available at
* http://www.eclipse.org/legal/epl-v20.html.
*
* SPDX-License-Identifier: EPL-2.0
*******************************************************************************/
package tools.refinery.viatra.runtime.internal.engine;
import static tools.refinery.viatra.runtime.matchers.util.Preconditions.checkArgument;
import java.util.HashSet;
import java.util.Set;
public abstract class ListenerContainer<Listener> {
protected final Set<Listener> listeners;
public ListenerContainer() {
this.listeners = new HashSet<Listener>();
}
public synchronized void addListener(Listener listener) {
checkArgument(listener != null, "Cannot add null listener!");
boolean added = listeners.add(listener);
if(added) {
listenerAdded(listener);
}
}
public synchronized void removeListener(Listener listener) {
checkArgument(listener != null, "Cannot remove null listener!");
boolean removed = listeners.remove(listener);
if(removed) {
listenerRemoved(listener);
}
}
protected abstract void listenerAdded(Listener listener);
protected abstract void listenerRemoved(Listener listener);
}
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