    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      }