hyracks-core/src/main/java/edu/uci/ics/hyracks/coreops/hadoop/data/WritableComparingComparatorFactory.java

/*
 * Copyright 2009-2010 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.coreops.hadoop.data;

import org.apache.hadoop.io.WritableComparable;
import org.apache.hadoop.io.WritableComparator;

import edu.uci.ics.hyracks.api.dataflow.value.IComparator;
import edu.uci.ics.hyracks.api.dataflow.value.IComparatorFactory;
import edu.uci.ics.hyracks.util.ReflectionUtils;

public class WritableComparingComparatorFactory<T> implements IComparatorFactory<WritableComparable<T>> {
    private Class<? extends WritableComparator> klass;

    public WritableComparingComparatorFactory(Class<? extends WritableComparator> klass) {
        this.klass = klass;
    }

    private static final long serialVersionUID = 1L;

    @Override
    public IComparator<WritableComparable<T>> createComparator() {
        final WritableComparator instance = ReflectionUtils.createInstance(klass);
        return new IComparator<WritableComparable<T>>() {
            @Override
            public int compare(WritableComparable<T> o1, WritableComparable<T> o2) {
                return instance.compare(o1, o2);
            }
        };
    }
}