/*
* 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 javax.annotation.Nullable;
/** An ordering that uses the reverse of a given order. */
@GwtCompatible(serializable = true)
final class ReverseOrdering<T> extends Ordering<T> implements Serializable {
final Ordering<? super T> forwardOrder;
ReverseOrdering(Ordering<? super T> forwardOrder) {
this.forwardOrder = checkNotNull(forwardOrder);
}
@Override public int compare(T a, T b) {
return forwardOrder.compare(b, a);
}
@SuppressWarnings("unchecked") // how to explain?
@Override public <S extends T> Ordering<S> reverse() {
return (Ordering<S>) forwardOrder;
}
// Override the six min/max methods to "hoist" delegation outside loops
@Override public <E extends T> E min(E a, E b) {
return forwardOrder.max(a, b);
}
@Override public <E extends T> E min(E a, E b, E c, E... rest) {
return forwardOrder.max(a, b, c, rest);
}
@Override public <E extends T> E min(Iterable<E> iterable) {
return forwardOrder.max(iterable);
}
@Override public <E extends T> E max(E a, E b) {
return forwardOrder.min(a, b);
}
@Override public <E extends T> E max(E a, E b, E c, E... rest) {
return forwardOrder.min(a, b, c, rest);
}
@Override public <E extends T> E max(Iterable<E> iterable) {
return forwardOrder.min(iterable);
}
@Override public int hashCode() {
return -forwardOrder.hashCode();
}
@Override public boolean equals(@Nullable Object object) {
if (object == this) {
return true;
}
if (object instanceof ReverseOrdering) {
ReverseOrdering<?> that = (ReverseOrdering<?>) object;
return this.forwardOrder.equals(that.forwardOrder);
}
return false;
}
@Override public String toString() {
return forwardOrder + ".reverse()";
}
private static final long serialVersionUID = 0;
}
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