001/*
002 * Copyright (c) 2016-2017 Chris K Wensel <chris@wensel.net>. All Rights Reserved.
003 * Copyright (c) 2007-2017 Xplenty, Inc. All Rights Reserved.
004 *
005 * Project and contact information: http://www.cascading.org/
006 *
007 * This file is part of the Cascading project.
008 *
009 * Licensed under the Apache License, Version 2.0 (the "License");
010 * you may not use this file except in compliance with the License.
011 * You may obtain a copy of the License at
012 *
013 *     http://www.apache.org/licenses/LICENSE-2.0
014 *
015 * Unless required by applicable law or agreed to in writing, software
016 * distributed under the License is distributed on an "AS IS" BASIS,
017 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
018 * See the License for the specific language governing permissions and
019 * limitations under the License.
020 */
021
022package cascading.operation;
023
024import cascading.flow.FlowProcess;
025
026/**
027 * Interface Filter marks a given {@link Operation} as a filter, as opposed to being a {@link Function}.
028 * <p>
029 * A Filter is responsible for testing a Tuple to see if it should be removed from the tuple stream.
030 * <p>
031 * To implement a Filter, (optionally) sub-class {@link BaseOperation} and have the new sub-class {@code implement}
032 * this interface.
033 */
034public interface Filter<Context> extends Operation<Context>
035  {
036  /**
037   * Method isRemove returns true if input should be removed from the tuple stream.
038   *
039   * @param flowProcess of type FlowProcess
040   * @param filterCall  of type FilterCall
041   * @return boolean
042   */
043  boolean isRemove( FlowProcess flowProcess, FilterCall<Context> filterCall );
044  }