/**
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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.adt;
import org.waveprotocol.wave.model.util.CollectionUtils;
import org.waveprotocol.wave.model.util.CopyOnWriteSet;
import org.waveprotocol.wave.model.util.ValueUtils;
import java.util.Collections;
import java.util.Map;
import java.util.Set;
/**
* A simple implementation of an {@linkplain ObservableBasicMap}.
*
*/
public class ObservableBasicMapImpl<K, V> implements ObservableBasicMap<K, V> {
/** Backing store for the collection's data. */
private final Map<K, V> data = CollectionUtils.newHashMap();
/** All the listeners for changes to this map. */
private final CopyOnWriteSet<Listener<? super K, ? super V>> listeners = CopyOnWriteSet.create();
/**
* Initializes a new, empty map.
*/
public ObservableBasicMapImpl() {
}
@Override
public void addListener(ObservableBasicMap.Listener<? super K, ? super V> listener) {
listeners.add(listener);
}
@Override
public void removeListener(ObservableBasicMap.Listener<? super K, ? super V> listener) {
listeners.remove(listener);
}
@Override
public V get(K key) {
return data.get(key);
}
@Override
public boolean put(K key, V newValue) {
V oldValue = data.put(key, newValue);
if (ValueUtils.equal(oldValue, newValue)) {
return false;
}
fireOnEntrySet(key, oldValue, newValue);
return true;
}
@Override
public Set<K> keySet() {
return Collections.unmodifiableSet(data.keySet());
}
@Override
public void remove(K key) {
V oldValue = data.remove(key);
if (oldValue != null) {
fireOnEntrySet(key, oldValue, null);
}
}
/** Fires the changed event. */
private void fireOnEntrySet(K key, V oldValue, V newValue) {
for (ObservableBasicMap.Listener<? super K, ? super V> listener : listeners) {
listener.onEntrySet(key, oldValue, newValue);
}
}
}