/**
* Copyright 2009 Google Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
*/
package org.waveprotocol.wave.model.document.util;
import org.waveprotocol.wave.model.document.MutableDocumentEvent;
import org.waveprotocol.wave.model.document.MutableDocumentListener;
import org.waveprotocol.wave.model.document.MutableDocumentListenerFactory;
import java.util.Arrays;
import java.util.HashSet;
import java.util.Set;
/**
* A mutable document listener factory which delegates to a set of other
* factories. The factory creates listeners which forward messages to all
* listeners provided by any of the delegate factories.
*
* Only used in wally.
*
* @author anorth@google.com (Alex North)
*/
public class DocumentListenerRegistry implements MutableDocumentListenerFactory {
private final Set<MutableDocumentListenerFactory> factories;
/**
* Constructs a new registry an initial series of delegate factories.
*
* @param factories factories to delegate to
*/
public DocumentListenerRegistry(MutableDocumentListenerFactory... factories) {
this.factories = new HashSet<MutableDocumentListenerFactory>(Arrays.asList(factories));
}
/**
* {@inheritDoc}.
*
* Creates a listener which forwards messages to all listeners for the
* document provided by registered factories.
*
* @return a forwarding listener, or null if no factories provided listeners.
*/
@Override
public MutableDocumentListener createDocumentListener(String documentId) {
final Set<MutableDocumentListener> listeners = new HashSet<MutableDocumentListener>();
for (MutableDocumentListenerFactory factory : factories) {
MutableDocumentListener interestedListener = factory.createDocumentListener(documentId);
if (interestedListener != null) {
listeners.add(interestedListener);
}
}
if (!listeners.isEmpty()) {
return forwardingListener(listeners);
}
return null;
}
/**
* Adds a factory to the set of delegate factories.
*/
public void addFactory(MutableDocumentListenerFactory factory) {
factories.add(factory);
}
/**
* Creates a listener which forwards messages to a set of delegate listeners.
*/
private MutableDocumentListener forwardingListener(final Set<MutableDocumentListener> delegates) {
return new MutableDocumentListener() {
@Override
public void onDocumentEvents(MutableDocumentEvent events) {
for (MutableDocumentListener listener : delegates) {
listener.onDocumentEvents(events);
}
}
};
}
}