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.pipe.joiner;
023
024import java.util.Iterator;
025
026import cascading.tuple.Fields;
027import cascading.tuple.Tuple;
028
029/**
030 * Class BufferJoiner notifies the Cascading planner that the next {@link cascading.operation.Buffer} instance
031 * will implement a custom join strategy.
032 * <p>
033 * Internally this class simply returns {@link Fields#NONE} from {@link #getFieldDeclaration()} as a flag to
034 * the planner.
035 */
036public class BufferJoin extends BaseJoiner
037  {
038  public BufferJoin()
039    {
040    super( Fields.NONE );
041    }
042
043  @Override
044  public Iterator<Tuple> getIterator( JoinerClosure closure )
045    {
046    return null;
047    }
048
049  @Override
050  public int numJoins()
051    {
052    return -1;
053    }
054  }