hyracks/hyracks-dataflow-std/src/main/java/edu/uci/ics/hyracks/dataflow/std/join/JoinComparator.java

/*
 * Copyright 2009-2013 by The Regents of the University of California
 * 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 from
 * 
 *     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 edu.uci.ics.hyracks.dataflow.std.join;

import edu.uci.ics.hyracks.api.comm.IFrameTupleAccessor;
import edu.uci.ics.hyracks.api.dataflow.value.IBinaryComparator;
import edu.uci.ics.hyracks.api.dataflow.value.ITuplePairComparator;

class JoinComparator implements ITuplePairComparator {
	 private final IBinaryComparator bComparator;
     private final int field0;
     private final int field1;

     public JoinComparator(IBinaryComparator bComparator, int field0, int field1) {
         this.bComparator = bComparator;
         this.field0 = field0;
         this.field1 = field1;
     }

     @Override
     public int compare(IFrameTupleAccessor accessor0, int tIndex0, IFrameTupleAccessor accessor1, int tIndex1) {
         int tStart0 = accessor0.getTupleStartOffset(tIndex0);
         int fStartOffset0 = accessor0.getFieldSlotsLength() + tStart0;

         int tStart1 = accessor1.getTupleStartOffset(tIndex1);
         int fStartOffset1 = accessor1.getFieldSlotsLength() + tStart1;

         int fStart0 = accessor0.getFieldStartOffset(tIndex0, field0);
         int fEnd0 = accessor0.getFieldEndOffset(tIndex0, field0);
         int fLen0 = fEnd0 - fStart0;

         int fStart1 = accessor1.getFieldStartOffset(tIndex1, field1);
         int fEnd1 = accessor1.getFieldEndOffset(tIndex1, field1);
         int fLen1 = fEnd1 - fStart1;

         int c = bComparator.compare(accessor0.getBuffer().array(), fStart0 + fStartOffset0, fLen0, accessor1
                 .getBuffer().array(), fStart1 + fStartOffset1, fLen1);
         if (c != 0) {
             return c;
         }
         return 0;
     }
}