    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.tuple.hadoop.util;
    022
    023import java.io.IOException;
    024import java.util.Comparator;
    025
    026import cascading.CascadingException;
    027import cascading.tuple.StreamComparator;
    028import cascading.tuple.io.TupleInputStream;
    029
    030/**
    031 *
    032 */
    033public class TypedTupleElementComparator implements StreamComparator<TupleInputStream>, Comparator<Object>
    034  {
    035  private Class type;
    036
    037  Comparator comparator = new Comparator<Comparable>()
    038  {
    039  @Override
    040  public int compare( Comparable lhs, Comparable rhs )
    041    {
    042    if( lhs == null && rhs == null )
    043      return 0;
    044
    045    if( lhs == null )
    046      return -1;
    047
    048    if( rhs == null )
    049      return 1;
    050
    051    return lhs.compareTo( rhs ); // guaranteed to not be null
    052    }
    053  };
    054
    055  public TypedTupleElementComparator()
    056    {
    057    }
    058
    059  public TypedTupleElementComparator( Class type, Comparator comparator )
    060    {
    061    this.type = type;
    062
    063    if( comparator != null )
    064      this.comparator = comparator;
    065    }
    066
    067  @Override
    068  public int compare( Object lhs, Object rhs )
    069    {
    070    return comparator.compare( lhs, rhs );
    071    }
    072
    073  @Override
    074  public int compare( TupleInputStream lhsStream, TupleInputStream rhsStream )
    075    {
    076    Object lhs;
    077    Object rhs;
    078
    079    try
    080      {
    081      lhs = lhsStream.readType( type );
    082      rhs = rhsStream.readType( type );
    083      }
    084    catch( IOException exception )
    085      {
    086      throw new CascadingException( "unable to read element from underlying stream", exception );
    087      }
    088
    089    try
    090      {
    091      return comparator.compare( lhs, rhs );
    092      }
    093    catch( Exception exception )
    094      {
    095      throw new CascadingException( "unable to compare Tuples, likely a CoGroup is being attempted on fields of " +
    096        "different types or custom comparators are incorrectly set on Fields, lhs: '" + lhs + "' rhs: '" + rhs + "'", exception );
    097      }
    098    }
    099  }