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.operation.filter;
022    
023    import java.beans.ConstructorProperties;
024    
025    import cascading.flow.FlowProcess;
026    import cascading.operation.Filter;
027    import cascading.operation.FilterCall;
028    import cascading.tuple.Fields;
029    import cascading.tuple.TupleEntry;
030    
031    /**
032     * Class Xor is a {@link Filter} class that will logically 'xor' (exclusive or) the results of the
033     * constructor provided Filter instances.
034     * <p/>
035     * Logically, if {@link Filter#isRemove(cascading.flow.FlowProcess, cascading.operation.FilterCall)} returns {@code true} for all given instances,
036     * or returns {@code false} for all given instances, this filter will return {@code false}.
037     * <p/>
038     * Note that Xor can only be applied to two values.
039     *
040     * @see And
041     * @see Or
042     * @see Not
043     */
044    public class Xor extends Logic
045      {
046      /**
047       * Constructor Xor creates a new Xor instance where all Filter instances receive all arguments.
048       *
049       * @param filters of type Filter...
050       */
051      @ConstructorProperties({"filters"})
052      public Xor( Filter... filters )
053        {
054        super( filters );
055        }
056    
057      /**
058       * Constructor Xor creates a new Xor instance.
059       *
060       * @param lhsArgumentSelector of type Fields
061       * @param lhsFilter           of type Filter
062       * @param rhsArgumentSelector of type Fields
063       * @param rhsFilter           of type Filter
064       */
065      @ConstructorProperties({"lhsArgumentsSelector", "lhsFilter", "rhsArgumentSelector", "rhsFilter"})
066      public Xor( Fields lhsArgumentSelector, Filter lhsFilter, Fields rhsArgumentSelector, Filter rhsFilter )
067        {
068        super( lhsArgumentSelector, lhsFilter, rhsArgumentSelector, rhsFilter );
069        }
070    
071      @Override
072      public boolean isRemove( FlowProcess flowProcess, FilterCall filterCall )
073        {
074        Context context = (Logic.Context) filterCall.getContext();
075    
076        TupleEntry lhsEntry = context.argumentEntries[ 0 ];
077        TupleEntry rhsEntry = context.argumentEntries[ 1 ];
078    
079        lhsEntry.setTuple( filterCall.getArguments().selectTuple( argumentSelectors[ 0 ] ) );
080        rhsEntry.setTuple( filterCall.getArguments().selectTuple( argumentSelectors[ 1 ] ) );
081    
082        boolean lhsResult = filters[ 0 ].isRemove( flowProcess, context.calls[ 0 ] );
083        boolean rhsResult = filters[ 1 ].isRemove( flowProcess, context.calls[ 1 ] );
084    
085        return lhsResult != rhsResult;
086        }
087      }