/*
* Copyright (c) 2007-2014 Concurrent, Inc. All Rights Reserved.
*
* Project and contact information: http://www.cascading.org/
*
* This file is part of the Cascading project.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package cascading.tuple.hadoop.util;
import java.io.IOException;
import java.util.Comparator;
import cascading.CascadingException;
import cascading.tuple.StreamComparator;
import cascading.tuple.io.TupleInputStream;
/**
*
*/
public class TupleElementComparator implements StreamComparator<TupleInputStream>, Comparator<Object>
{
Comparator comparator = new Comparator<Comparable>()
{
@Override
public int compare( Comparable lhs, Comparable rhs )
{
if( lhs == null && rhs == null )
return 0;
if( lhs == null )
return -1;
if( rhs == null )
return 1;
return lhs.compareTo( rhs ); // guaranteed to not be null
}
};
public TupleElementComparator()
{
}
public TupleElementComparator( Comparator comparator )
{
if( comparator != null )
this.comparator = comparator;
}
@Override
public int compare( Object lhs, Object rhs )
{
return comparator.compare( lhs, rhs );
}
@Override
public int compare( TupleInputStream lhsStream, TupleInputStream rhsStream )
{
Object lhs;
Object rhs;
try
{
lhs = lhsStream.getNextElement();
rhs = rhsStream.getNextElement();
}
catch( IOException exception )
{
throw new CascadingException( "unable to read element from underlying stream", exception );
}
try
{
return comparator.compare( lhs, rhs );
}
catch( Exception exception )
{
throw new CascadingException( "unable to compare Tuples, likely a CoGroup is being attempted on fields of " +
"different types or custom comparators are incorrectly set on Fields, lhs: '" + lhs + "' rhs: '" + rhs + "'", exception );
}
}
}