return (delegate != null)
        ? delegate.toArray(a)
        : ObjectArrays.toArrayImpl(requireElements(), 0, size, a);
  }

  /**
   * Ensures that this {@code CompactHashSet} has the smallest representation in memory, given its
   * current size.
   */
  public void trimToSize() {
    if (needsAllocArrays()) {
      return;
    }
    Set<E> delegate = delegateOrNull();

  /**
   * Returns an array size suitable for the backing array of a hash table that uses open addressing
   * with linear probing in its implementation. The returned size is the smallest power of two that
   * can hold setSize elements with the desired load factor. Always returns at least setSize + 2.
   */
  @VisibleForTesting
  static int chooseTableSize(int setSize) {
    setSize = max(setSize, 2);

    TreeRangeSet<C> result = create();
    result.addAll(rangeSet);
    return result;
  }

  /**
   * Returns a {@code TreeRangeSet} representing the union of the specified ranges.
   *
   * <p>This is the smallest {@code RangeSet} which encloses each of the specified ranges. An
   * element will be contained in this {@code RangeSet} if and only if it is contained in at least
   * one {@code Range} in {@code ranges}.
   *
   * @since 21.0

  /**
   * Returns an array size suitable for the backing array of a hash table that uses open addressing
   * with linear probing in its implementation. The returned size is the smallest power of two that
   * can hold setSize elements with the desired load factor. Always returns at least setSize + 2.
   */
  // TODO(cpovirk): Move to Hashing or something, since it's used elsewhere in the Android version.

      // long overflows.
    }
    int k = LongMath.biggestBinomials.length;
    assertFalse(fitsInLong(BigIntegerMath.binomial(2 * k, k)));
    // 2 * k is the smallest value for which we don't replace k with (n-k).
  }

  @GwtIncompatible // TODO
  public void testConstantsBiggestSimpleBinomials() {
    for (int i = 0; i < LongMath.biggestSimpleBinomials.length; i++) {

   * href="http://mathworld.wolfram.com/PrimeNumber.html">prime number</a>: an integer <i>greater
   * than one</i> that cannot be factored into a product of <i>smaller</i> positive integers.
   * Returns {@code false} if {@code n} is zero, one, or a composite number (one which <i>can</i> be
   * factored into smaller positive integers).
   *
   * <p>To test larger numbers, use {@link LongMath#isPrime} or {@link BigInteger#isProbablePrime}.
   *

      // Many spliterators will have trySplits that are SUBSIZED even if they are not themselves
      // SUBSIZED.
      if (spliterator.hasCharacteristics(Spliterator.SUBSIZED)) {
        // we can drill down to exactly the smallest nonempty spliterator
        while (true) {
          Spliterator<T> prefix = spliterator.trySplit();
          if (prefix == null || prefix.getExactSizeIfKnown() == 0) {
            break;

      @Override
      @ParametricNullness
      V getOutput(int entry) {
        return value(entry);
      }
    };
  }

  /**
   * Ensures that this {@code CompactHashMap} has the smallest representation in memory, given its
   * current size.
   */
  public void trimToSize() {
    if (needsAllocArrays()) {
      return;
    }
    Map<K, V> delegate = delegateOrNull();

      // Many spliterators will have trySplits that are SUBSIZED even if they are not themselves
      // SUBSIZED.
      if (spliterator.hasCharacteristics(Spliterator.SUBSIZED)) {
        // we can drill down to exactly the smallest nonempty spliterator
        while (true) {
          Spliterator<T> prefix = spliterator.trySplit();
          if (prefix == null || prefix.getExactSizeIfKnown() == 0) {
            break;

      @Override
      @ParametricNullness
      V getOutput(int entry) {
        return value(entry);
      }
    };
  }

  /**
   * Ensures that this {@code CompactHashMap} has the smallest representation in memory, given its
   * current size.
   */
  public void trimToSize() {
    if (needsAllocArrays()) {
      return;
    }
    Map<K, V> delegate = delegateOrNull();