    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.operation.aggregator;
    022
    023import java.beans.ConstructorProperties;
    024import java.util.Collection;
    025import java.util.Collections;
    026import java.util.HashSet;
    027
    028import cascading.flow.FlowProcess;
    029import cascading.operation.Aggregator;
    030import cascading.operation.AggregatorCall;
    031import cascading.operation.BaseOperation;
    032import cascading.operation.OperationCall;
    033import cascading.tuple.Fields;
    034import cascading.tuple.Tuple;
    035import cascading.tuple.TupleEntry;
    036
    037/** Class ExtentBase is the base class for First and Last. */
    038public abstract class ExtentBase extends BaseOperation<Tuple[]> implements Aggregator<Tuple[]>
    039  {
    040  /** Field ignoreTuples */
    041  private final Collection<Tuple> ignoreTuples;
    042
    043  @ConstructorProperties({"fieldDeclaration"})
    044  protected ExtentBase( Fields fieldDeclaration )
    045    {
    046    super( fieldDeclaration );
    047    this.ignoreTuples = null;
    048    }
    049
    050  @ConstructorProperties({"numArgs", "fieldDeclaration"})
    051  protected ExtentBase( int numArgs, Fields fieldDeclaration )
    052    {
    053    super( numArgs, fieldDeclaration );
    054    ignoreTuples = null;
    055    }
    056
    057  @ConstructorProperties({"fieldDeclaration", "ignoreTuples"})
    058  protected ExtentBase( Fields fieldDeclaration, Tuple... ignoreTuples )
    059    {
    060    super( fieldDeclaration );
    061    this.ignoreTuples = new HashSet<Tuple>();
    062    Collections.addAll( this.ignoreTuples, ignoreTuples );
    063    }
    064
    065  public Collection<Tuple> getIgnoreTuples()
    066    {
    067    return Collections.unmodifiableCollection( ignoreTuples );
    068    }
    069
    070  @Override
    071  public void prepare( FlowProcess flowProcess, OperationCall<Tuple[]> operationCall )
    072    {
    073    operationCall.setContext( new Tuple[ 1 ] );
    074    }
    075
    076  @Override
    077  public void start( FlowProcess flowProcess, AggregatorCall<Tuple[]> aggregatorCall )
    078    {
    079    aggregatorCall.getContext()[ 0 ] = null;
    080    }
    081
    082  @Override
    083  public void aggregate( FlowProcess flowProcess, AggregatorCall<Tuple[]> aggregatorCall )
    084    {
    085    if( ignoreTuples != null && ignoreTuples.contains( aggregatorCall.getArguments().getTuple() ) )
    086      return;
    087
    088    performOperation( aggregatorCall.getContext(), aggregatorCall.getArguments() );
    089    }
    090
    091  protected abstract void performOperation( Tuple[] context, TupleEntry entry );
    092
    093  @Override
    094  public void complete( FlowProcess flowProcess, AggregatorCall<Tuple[]> aggregatorCall )
    095    {
    096    if( aggregatorCall.getContext()[ 0 ] != null )
    097      aggregatorCall.getOutputCollector().add( getResult( aggregatorCall ) );
    098    }
    099
    100  protected Tuple getResult( AggregatorCall<Tuple[]> aggregatorCall )
    101    {
    102    return aggregatorCall.getContext()[ 0 ];
    103    }
    104
    105  @Override
    106  public boolean equals( Object object )
    107    {
    108    if( this == object )
    109      return true;
    110    if( !( object instanceof ExtentBase ) )
    111      return false;
    112    if( !super.equals( object ) )
    113      return false;
    114
    115    ExtentBase that = (ExtentBase) object;
    116
    117    if( ignoreTuples != null ? !ignoreTuples.equals( that.ignoreTuples ) : that.ignoreTuples != null )
    118      return false;
    119
    120    return true;
    121    }
    122
    123  @Override
    124  public int hashCode()
    125    {
    126    int result = super.hashCode();
    127    result = 31 * result + ( ignoreTuples != null ? ignoreTuples.hashCode() : 0 );
    128    return result;
    129    }
    130  }