/*
    * 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.Comparator;
  
  import javax.annotation.Nullable;
  
  /** An ordering for a pre-existing comparator. */
  @GwtCompatible(serializable = true)
  final class ComparatorOrdering<T> extends Ordering<T> implements Serializable {
    final Comparator<T> comparator;
  
    ComparatorOrdering(Comparator<T> comparator) {
      this.comparator = checkNotNull(comparator);
    }
  
    @Override public int compare(T a, T b) {
      return comparator.compare(a, b);
    }
  
    @Override public boolean equals(@Nullable Object object) {
      if (object == this) {
        return true;
      }
      if (object instanceof ComparatorOrdering) {
        ComparatorOrdering<?> that = (ComparatorOrdering<?>) object;
        return this.comparator.equals(that.comparator);
      }
      return false;
    }
  
    @Override public int hashCode() {
      return comparator.hashCode();
    }
  
    @Override public String toString() {
      return comparator.toString();
    }
  
    private static final long serialVersionUID = 0;
  }