/*
 * Copyright (c) 2007-2017 Xplenty, Inc. All Rights Reserved.
 *
 * Project and contact information: http://www.cascading.org/
 *
 * This file is part of the Cascading project.
 *
 * 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 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 cascading.util;

import java.io.Serializable;
import java.util.Comparator;

/**
 * Class NullNotEquivalentComparator simply returns -1 if the lhs is null, 1 if the rhs is null, or
 * the result of {@code lhs.compareTo(rhs)}.
 * <p/>
 * Use this {@link Comparator} when performing a {@link cascading.pipe.CoGroup} that needs SQL like semantics.
 */
public class NullNotEquivalentComparator implements Comparator<Comparable>, Serializable
  {
  @Override
  public int compare( Comparable lhs, Comparable rhs )
    {
    if( lhs == null )
      return -1;

    if( rhs == null )
      return 1;

    return lhs.compareTo( rhs );
    }
  }
