    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.Arrays;
    025    import java.util.Iterator;
    026
    027    import cascading.tuple.Fields;
    028    import 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     */
    041    public 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      }