/*
* Copyright © 2014 Cask Data, 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 co.cask.cdap.common.collect;
import java.util.Collection;
/**
* This can be used to collect with different strategies while iterating
* over a stream of elements. For every element in the stream, add the
* element to the collector. The collector then indicates whether more
* elements are needed (for instance, to collect the first N elements only,
* use a collector that returns false after the Nth element has been added.
*
* @param <Element> Type of element.
*/
public interface Collector<Element> {
/**
* collect one element.
* @param element the element to collect
* @return whether more elements need to be collected
*/
boolean addElement(Element element);
/**
* Finish collection of elements and add all collected elements into the given {@link Collection}.
*
* @param collection {@link Collection} for storing collected elements.
* @param <T> Type of collection
* @return The same {@link Collection} instance given in the parameter.
*/
<T extends Collection<? super Element>> T finish(T collection);
}