001/*
002 * Copyright (c) 2007-2017 Xplenty, 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.pipe.joiner;
022
023import java.beans.ConstructorProperties;
024import java.util.Iterator;
025
026import cascading.tuple.Fields;
027import cascading.tuple.Tuple;
028
029/**
030 * Class RightJoin will return an {@link Iterator} that will iterate over a given {@link Joiner} and return tuples that represent
031 * a left outer, right inner join of the CoGrouper internal grouped tuple collections.
032 * <p/>
033 * Note only the farthest left tuple stream will be used as the outer join. All following joins to the right will
034 * be inner joins. See {@link MixedJoin} for more flexibility.
035 * <p/>
036 * Joins perform based on the equality of the join keys. In the case of null values, Java treats two
037 * null values as equivalent. SQL does not treat null values as equal. To produce SQL like results in a given
038 * join, a new {@link java.util.Comparator} will need to be used on the joined values to prevent null from
039 * equaling null. As a convenience, see the {@link cascading.util.NullNotEquivalentComparator} class.
040 *
041 * @see MixedJoin
042 */
043public class RightJoin extends BaseJoiner
044  {
045  public RightJoin()
046    {
047    }
048
049  @ConstructorProperties({"fieldDeclaration"})
050  public RightJoin( Fields fieldDeclaration )
051    {
052    super( fieldDeclaration );
053    }
054
055  public Iterator<Tuple> getIterator( JoinerClosure closure )
056    {
057    return new JoinIterator( closure );
058    }
059
060  public int numJoins()
061    {
062    return -1;
063    }
064
065  public static class JoinIterator extends OuterJoin.JoinIterator
066    {
067    public JoinIterator( JoinerClosure closure )
068      {
069      super( closure );
070      }
071
072    @Override
073    protected boolean isOuter( int i )
074      {
075      return i == 0 && super.isOuter( i );
076      }
077    }
078  }