/*
    * 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;
  
  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 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(Iterator<E> iterator) {
      return forwardOrder.max(iterator);
    }
  
    @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(Iterator<E> iterator) {
      return forwardOrder.min(iterator);
    }
  
    @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;
 }