/*
* 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;
/** 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 six 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(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(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;
}
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