001/*
002 * Copyright (c) 2007-2016 Concurrent, Inc. All Rights Reserved.
003 *
004 * Project and contact information: http://www.cascading.org/
005 *
006 * This file is part of the Cascading project.
007 *
008 * Licensed under the Apache License, Version 2.0 (the "License");
009 * you may not use this file except in compliance with the License.
010 * You may obtain a copy of the License at
011 *
012 *     http://www.apache.org/licenses/LICENSE-2.0
013 *
014 * Unless required by applicable law or agreed to in writing, software
015 * distributed under the License is distributed on an "AS IS" BASIS,
016 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
017 * See the License for the specific language governing permissions and
018 * limitations under the License.
019 */
020
021package cascading.operation;
022
023import cascading.flow.FlowProcess;
024
025/**
026 * Interface Filter marks a given {@link Operation} as a filter, as opposed to being a {@link Function}.
027 * <p/>
028 * A Filter is responsible for testing a Tuple to see if it should be removed from the tuple stream.
029 * <p/>
030 * To implement a Filter, (optionally) sub-class {@link BaseOperation} and have the new sub-class {@code implement}
031 * this interface.
032 */
033public interface Filter<Context> extends Operation<Context>
034  {
035  /**
036   * Method isRemove returns true if input should be removed from the tuple stream.
037   *
038   * @param flowProcess of type FlowProcess
039   * @param filterCall  of type FilterCall
040   * @return boolean
041   */
042  boolean isRemove( FlowProcess flowProcess, FilterCall<Context> filterCall );
043  }