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      }