/**
* 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.adt;
/**
* Extension of a {@link MonotonicValue} that broadcasts events whenever
* the value changes.
*
*/
public interface ObservableMonotonicValue<C extends Comparable<C>> extends MonotonicValue<C> {
public interface Listener<C> {
/**
* Notifies this listener that the value has increased, or been removed
* (in which case the new value is null). In the latter case, the value
* is no longer usable.
*
* @param newValue new value
*/
void onSet(C oldValue, C newValue);
}
/**
* Adds a listener.
*
* @param l listener to add
*/
void addListener(Listener<? super C> l);
/**
* Removes a listener.
*
* @param l listener to remove
*/
void removeListener(Listener<? super C> l);
}