/*
    * 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 com.google.common.annotations.GwtCompatible;
  
  import java.io.Serializable;
  import java.util.Comparator;
  
  /** An ordering that tries several comparators in order. */
  @GwtCompatible(serializable = true)
  final class CompoundOrdering<T> extends Ordering<T> implements Serializable {
    final ImmutableList<Comparator<? super T>> comparators;
  
    CompoundOrdering(Comparator<? super T> primary,
        Comparator<? super T> secondary) {
      this.comparators
          = ImmutableList.<Comparator<? super T>>of(primary, secondary);
    }
  
    CompoundOrdering(Iterable<? extends Comparator<? super T>> comparators) {
      this.comparators = ImmutableList.copyOf(comparators);
    }
  
    @Override public int compare(T left, T right) {
      // Avoid using the Iterator to avoid generating garbage (issue 979).
      int size = comparators.size();
      for (int i = 0; i < size; i++) {
        int result = comparators.get(i).compare(left, right);
        if (result != 0) {
          return result;
        }
      }
      return 0;
    }
  
    @Override public boolean equals(Object object) {
      if (object == this) {
        return true;
      }
      if (object instanceof CompoundOrdering) {
        CompoundOrdering<?> that = (CompoundOrdering<?>) object;
        return this.comparators.equals(that.comparators);
      }
      return false;
    }
  
    @Override public int hashCode() {
      return comparators.hashCode();
    }
  
    @Override public String toString() {
      return "Ordering.compound(" + comparators + ")";
    }
  
    private static final long serialVersionUID = 0;
  }