001/* 002 * Copyright (c) 2007-2015 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 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 TupleElementComparator implements StreamComparator<TupleInputStream>, Comparator<Object> 034 { 035 Comparator comparator = new Comparator<Comparable>() 036 { 037 @Override 038 public int compare( Comparable lhs, Comparable rhs ) 039 { 040 if( lhs == null && rhs == null ) 041 return 0; 042 043 if( lhs == null ) 044 return -1; 045 046 if( rhs == null ) 047 return 1; 048 049 return lhs.compareTo( rhs ); // guaranteed to not be null 050 } 051 }; 052 053 public TupleElementComparator() 054 { 055 } 056 057 public TupleElementComparator( Comparator comparator ) 058 { 059 if( comparator != null ) 060 this.comparator = comparator; 061 } 062 063 @Override 064 public int compare( Object lhs, Object rhs ) 065 { 066 return comparator.compare( lhs, rhs ); 067 } 068 069 @Override 070 public int compare( TupleInputStream lhsStream, TupleInputStream rhsStream ) 071 { 072 Object lhs; 073 Object rhs; 074 075 try 076 { 077 lhs = lhsStream.getNextElement(); 078 rhs = rhsStream.getNextElement(); 079 } 080 catch( IOException exception ) 081 { 082 throw new CascadingException( "unable to read element from underlying stream", exception ); 083 } 084 085 try 086 { 087 return comparator.compare( lhs, rhs ); 088 } 089 catch( Exception exception ) 090 { 091 throw new CascadingException( "unable to compare Tuples, likely a CoGroup is being attempted on fields of " + 092 "different types or custom comparators are incorrectly set on Fields, lhs: '" + lhs + "' rhs: '" + rhs + "'", exception ); 093 } 094 } 095 }