    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.Arrays;
    025import java.util.Iterator;
    026
    027import cascading.tuple.Fields;
    028import cascading.tuple.Tuple;
    029
    030/**
    031 * Class MixedJoin will return an {@link java.util.Iterator} that will iterate over a given
    032 * {@link Joiner} and return tuples that represent a join as defined by the given boolean array.
    033 * <p/>
    034 * So if joining three streams, {@code boolean []{true,false,false}} will result in a 'inner', 'outer', 'outer' join.
    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 */
    041public class MixedJoin extends BaseJoiner
    042  {
    043  /** Field INNER */
    044  public static boolean INNER = true;
    045  /** Field OUTER */
    046  public static boolean OUTER = false;
    047
    048  final boolean[] asInner;
    049
    050  /**
    051   * Constructor MixedJoin creates a new MixedJoin instance.
    052   *
    053   * @param asInner of type boolean[]
    054   */
    055  @ConstructorProperties({"asInner"})
    056  public MixedJoin( boolean[] asInner )
    057    {
    058    this.asInner = Arrays.copyOf( asInner, asInner.length );
    059    }
    060
    061  @ConstructorProperties({"fieldDeclaration", "asInner"})
    062  public MixedJoin( Fields fieldDeclaration, boolean[] asInner )
    063    {
    064    super( fieldDeclaration );
    065    this.asInner = asInner;
    066    }
    067
    068  /** @see Joiner#numJoins() */
    069  public int numJoins()
    070    {
    071    return asInner.length - 1;
    072    }
    073
    074  public Iterator<Tuple> getIterator( JoinerClosure closure )
    075    {
    076    return new JoinIterator( closure );
    077    }
    078
    079  public class JoinIterator extends OuterJoin.JoinIterator
    080    {
    081    public JoinIterator( JoinerClosure closure )
    082      {
    083      super( closure );
    084      }
    085
    086    @Override
    087    protected boolean isOuter( int i )
    088      {
    089      return !asInner[ i ] && super.isOuter( i );
    090      }
    091    }
    092  }