/*
 * Copyright (C) 2007 The Guava Authors
 *
 * 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 com.google.common.collect;

import static com.google.common.base.Preconditions.checkNotNull;

import com.google.common.annotations.GwtCompatible;
import java.io.Serializable;
import java.util.Iterator;

An ordering that uses the reverse of the natural order of the values.
/** An ordering that uses the reverse of the natural order of the values. */
@GwtCompatible(serializable = true) @SuppressWarnings("unchecked") // TODO(kevinb): the right way to explain this?? final class ReverseNaturalOrdering extends Ordering<Comparable> implements Serializable { static final ReverseNaturalOrdering INSTANCE = new ReverseNaturalOrdering(); @Override public int compare(Comparable left, Comparable right) { checkNotNull(left); // right null is caught later if (left == right) { return 0; } return right.compareTo(left); } @Override public <S extends Comparable> Ordering<S> reverse() { return Ordering.natural(); } // Override the min/max methods to "hoist" delegation outside loops @Override public <E extends Comparable> E min(E a, E b) { return NaturalOrdering.INSTANCE.max(a, b); } @Override public <E extends Comparable> E min(E a, E b, E c, E... rest) { return NaturalOrdering.INSTANCE.max(a, b, c, rest); } @Override public <E extends Comparable> E min(Iterator<E> iterator) { return NaturalOrdering.INSTANCE.max(iterator); } @Override public <E extends Comparable> E min(Iterable<E> iterable) { return NaturalOrdering.INSTANCE.max(iterable); } @Override public <E extends Comparable> E max(E a, E b) { return NaturalOrdering.INSTANCE.min(a, b); } @Override public <E extends Comparable> E max(E a, E b, E c, E... rest) { return NaturalOrdering.INSTANCE.min(a, b, c, rest); } @Override public <E extends Comparable> E max(Iterator<E> iterator) { return NaturalOrdering.INSTANCE.min(iterator); } @Override public <E extends Comparable> E max(Iterable<E> iterable) { return NaturalOrdering.INSTANCE.min(iterable); } // preserving singleton-ness gives equals()/hashCode() for free private Object readResolve() { return INSTANCE; } @Override public String toString() { return "Ordering.natural().reverse()"; } private ReverseNaturalOrdering() {} private static final long serialVersionUID = 0; }