001    /*
002     * Copyright (c) 2007-2014 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    
021    package cascading.pipe.joiner;
022    
023    import java.beans.ConstructorProperties;
024    import java.util.Iterator;
025    
026    import cascading.tuple.Fields;
027    import 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     */
043    public 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      }