/**
 * Helper type to implement rounding {@code X} to a representable {@code double} value according to
 * a {@link RoundingMode}.
 */
@GwtIncompatible
@ElementTypesAreNonnullByDefault
abstract class ToDoubleRounder<X extends Number & Comparable<X>> {
  /**
   * Returns x rounded to either the greatest double less than or equal to the precise value of x,
   * or the least double greater than or equal to the precise value of x.
   */

/**
 * Helper type to implement rounding {@code X} to a representable {@code double} value according to
 * a {@link RoundingMode}.
 */
@GwtIncompatible
@ElementTypesAreNonnullByDefault
abstract class ToDoubleRounder<X extends Number & Comparable<X>> {
  /**
   * Returns x rounded to either the greatest double less than or equal to the precise value of x,
   * or the least double greater than or equal to the precise value of x.
   */

   */
  public static double roundToDouble(BigDecimal x, RoundingMode mode) {
    return BigDecimalToDoubleRounder.INSTANCE.roundToDouble(x, mode);
  }

  private static class BigDecimalToDoubleRounder extends ToDoubleRounder<BigDecimal> {
    static final BigDecimalToDoubleRounder INSTANCE = new BigDecimalToDoubleRounder();

    private BigDecimalToDoubleRounder() {}

    @Override

   */
  public static double roundToDouble(BigDecimal x, RoundingMode mode) {
    return BigDecimalToDoubleRounder.INSTANCE.roundToDouble(x, mode);
  }

  private static class BigDecimalToDoubleRounder extends ToDoubleRounder<BigDecimal> {
    static final BigDecimalToDoubleRounder INSTANCE = new BigDecimalToDoubleRounder();

    private BigDecimalToDoubleRounder() {}

    @Override