* @since 2.0
 */
@GwtCompatible
public abstract class ComparisonChain {
  private ComparisonChain() {}

  /** Begins a new chained comparison statement. See example in the class documentation. */
  public static ComparisonChain start() {
    return ACTIVE;
  }

  private static final ComparisonChain ACTIVE =
      new ComparisonChain() {
        @SuppressWarnings("unchecked") // unsafe; see discussion on supertype

 * @since 2.0
 */
@GwtCompatible
public abstract class ComparisonChain {
  private ComparisonChain() {}

  /** Begins a new chained comparison statement. See example in the class documentation. */
  public static ComparisonChain start() {
    return ACTIVE;
  }

  private static final ComparisonChain ACTIVE =
      new ComparisonChain() {
        @SuppressWarnings("unchecked") // unsafe; see discussion on supertype

                    return new Ordering<Entry<String, String>>() {
                      @Override
                      public int compare(Entry<String, String> left, Entry<String, String> right) {
                        return ComparisonChain.start()
                            .compare(left.getKey(), right.getKey(), Ordering.natural().nullsFirst())
                            .compare(

                    return new Ordering<Entry<String, String>>() {
                      @Override
                      public int compare(Entry<String, String> left, Entry<String, String> right) {
                        return ComparisonChain.start()
                            .compare(left.getKey(), right.getKey(), Ordering.natural().nullsFirst())
                            .compare(

    static final Ordering<?> INSTANCE = new RangeLexOrdering();

    @Override
    public int compare(Range<?> left, Range<?> right) {
      return ComparisonChain.start()
          .compare(left.lowerBound, right.lowerBound)
          .compare(left.upperBound, right.upperBound)
          .result();
    }

    static final Ordering<?> INSTANCE = new RangeLexOrdering();

    @Override
    public int compare(Range<?> left, Range<?> right) {
      return ComparisonChain.start()
          .compare(left.lowerBound, right.lowerBound)
          .compare(left.upperBound, right.upperBound)
          .result();
    }

      // to be sorted based on the top of each iterator, with insertion order as tiebreaker
      Comparator<IndexedIterator<T>> heapComparator =
          (o1, o2) ->
              ComparisonChain.start()
                  .compare(o1.iterator.peek(), o2.iterator.peek(), itemComparator)
                  // When elements are equal, use insertion order to maintain stability

      // to be sorted based on the top of each iterator, with insertion order as tiebreaker
      Comparator<IndexedIterator<T>> heapComparator =
          (o1, o2) ->
              ComparisonChain.start()
                  .compare(o1.iterator.peek(), o2.iterator.peek(), itemComparator)
                  // When elements are equal, use insertion order to maintain stability