hivesterix/src/main/java/edu/uci/ics/hivesterix/runtime/factory/comparator/HiveStringBinaryDescComparatorFactory.java

package edu.uci.ics.hivesterix.runtime.factory.comparator;

import org.apache.hadoop.io.WritableComparator;

import edu.uci.ics.hivesterix.serde.lazy.LazyUtils;
import edu.uci.ics.hivesterix.serde.lazy.LazyUtils.VInt;
import edu.uci.ics.hyracks.api.dataflow.value.IBinaryComparator;
import edu.uci.ics.hyracks.api.dataflow.value.IBinaryComparatorFactory;

public class HiveStringBinaryDescComparatorFactory implements
		IBinaryComparatorFactory {
	private static final long serialVersionUID = 1L;

	public static HiveStringBinaryDescComparatorFactory INSTANCE = new HiveStringBinaryDescComparatorFactory();

	private HiveStringBinaryDescComparatorFactory() {
	}

	@Override
	public IBinaryComparator createBinaryComparator() {
		return new IBinaryComparator() {
			private VInt leftLen = new VInt();
			private VInt rightLen = new VInt();

			@Override
			public int compare(byte[] b1, int s1, int l1, byte[] b2, int s2,
					int l2) {
				LazyUtils.readVInt(b1, s1, leftLen);
				LazyUtils.readVInt(b2, s2, rightLen);

				if (leftLen.value + leftLen.length != l1
						|| rightLen.value + rightLen.length != l2)
					throw new IllegalStateException(
							"parse string: length mismatch, expected "
									+ (leftLen.value + leftLen.length) + ", "
									+ (rightLen.value + rightLen.length)
									+ " but get " + l1 + ", " + l2);

				return -WritableComparator.compareBytes(b1,
						s1 + leftLen.length, l1 - leftLen.length, b2, s2
								+ rightLen.length, l2 - rightLen.length);
			}
		};
	}
}