final Comparator<? super E> comparator;
    final int size;

    OrderedPermutationCollection(Iterable<E> input, Comparator<? super E> comparator) {
      this.inputList = ImmutableList.sortedCopyOf(comparator, input);
      this.comparator = comparator;
      this.size = calculateSize(inputList, comparator);
    }

    /**
     * The number of permutations with repeated elements is calculated as follows:

   * @since 3.0
   */
  // TODO(kevinb): rerun benchmarks including new options
  public <E extends @NonNull T> ImmutableList<E> immutableSortedCopy(Iterable<E> elements) {
    return ImmutableList.sortedCopyOf(this, elements);
  }

  /**
   * Returns {@code true} if each element in {@code iterable} after the first is greater than or

   * @since 3.0
   */
  // TODO(kevinb): rerun benchmarks including new options
  public <E extends @NonNull T> ImmutableList<E> immutableSortedCopy(Iterable<E> elements) {
    return ImmutableList.sortedCopyOf(this, elements);
  }

  /**
   * Returns {@code true} if each element in {@code iterable} after the first is greater than or