/**
* Copyright 2010 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.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);
}
}
}