/*
    * Copyright (C) 2012 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 com.google.common.annotations.GwtCompatible;
  
  import java.io.Serializable;
  import java.util.List;
  
  import javax.annotation.Nullable;
  
  /**
   * An ordering that treats all references as equals, even nulls.
   *
   * @author Emily Soldal
   */
  @GwtCompatible(serializable = true)
  final class AllEqualOrdering extends Ordering<Object> implements Serializable {
    static final AllEqualOrdering INSTANCE = new AllEqualOrdering();
  
    @Override
    public int compare(@Nullable Object left, @Nullable Object right) {
      return 0;
    }
  
    @Override
    public <E> List<E> sortedCopy(Iterable<E> iterable) {
      return Lists.newArrayList(iterable);
    }
  
    @Override
    public <E> ImmutableList<E> immutableSortedCopy(Iterable<E> iterable) {
      return ImmutableList.copyOf(iterable);
    }
  
    @SuppressWarnings("unchecked")
    @Override
    public <S> Ordering<S> reverse() {
      return (Ordering<S>) this;
    }
  
    private Object readResolve() {
      return INSTANCE;
    }
  
    @Override
    public String toString() {
      return "Ordering.allEqual()";
    }
  
    private static final long serialVersionUID = 0;
  }