flink-core/src/main/java/org/apache/flink/api/common/typeutils/base/BasicTypeComparator.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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 org.apache.flink.api.common.typeutils.base;

import java.io.IOException;

import org.apache.flink.annotation.Internal;
import org.apache.flink.api.common.typeutils.TypeComparator;
import org.apache.flink.core.memory.DataInputView;
import org.apache.flink.core.memory.DataOutputView;

@Internal
public abstract class BasicTypeComparator<T extends Comparable<T>> extends TypeComparator<T> implements java.io.Serializable {

	private static final long serialVersionUID = 1L;
	
	private transient T reference;
	
	protected final boolean ascendingComparison;

	// For use by getComparators
	@SuppressWarnings("rawtypes")
	private final TypeComparator[] comparators = new TypeComparator[] {this};
	

	protected BasicTypeComparator(boolean ascending) {
		this.ascendingComparison = ascending;
	}

	@Override
	public int hash(T value) {
		return value.hashCode();
	}

	@Override
	public void setReference(T toCompare) {
		this.reference = toCompare;
	}

	@Override
	public boolean equalToReference(T candidate) {
		return candidate.equals(reference);
	}

	@Override
	public int compareToReference(TypeComparator<T> referencedComparator) {
		int comp = ((BasicTypeComparator<T>) referencedComparator).reference.compareTo(reference);
		return ascendingComparison ? comp : -comp;
	}

	@Override
	public int compare(T first, T second) {
		int cmp = first.compareTo(second);
		return ascendingComparison ? cmp : -cmp;
	}

	@Override
	public boolean invertNormalizedKey() {
		return !ascendingComparison;
	}
	
	@Override
	public boolean supportsSerializationWithKeyNormalization() {
		return false;
	}

	@Override
	public void writeWithKeyNormalization(T record, DataOutputView target) throws IOException {
		throw new UnsupportedOperationException();
	}

	@Override
	public int extractKeys(Object record, Object[] target, int index) {
		target[index] = record;
		return 1;
	}

	@SuppressWarnings("rawtypes")
	@Override
	public TypeComparator[] getFlatComparators() {
		return comparators;
	}

	@Override
	public T readWithKeyDenormalization(T reuse, DataInputView source) throws IOException {
		throw new UnsupportedOperationException();
	}
}