private static long shiftMix(long val) {
    return val ^ (val >>> 47);
  }

  /** Implementation of Hash128to64 from util/hash/hash128to64.h */
  @VisibleForTesting
  static long hash128to64(long high, long low) {
    long a = (low ^ high) * K3;
    a ^= a >>> 47;
    long b = (high ^ a) * K3;
    b ^= b >>> 47;
    b *= K3;
    return b;
  }

  /**

    int k1 = mixK1(input);
    int h1 = mixH1(seed, k1);

    return fmix(h1, Ints.BYTES);
  }

  @Override
  public HashCode hashLong(long input) {
    int low = (int) input;
    int high = (int) (input >>> 32);

    int k1 = mixK1(low);
    int h1 = mixH1(seed, k1);

    k1 = mixK1(high);
    h1 = mixH1(h1, k1);

    return fmix(h1, Longs.BYTES);
  }

  @Override

    // Two differing invalid pairs.
    assertEquals("\uDCABdef", Strings.commonSuffix("abc\uDCAB\uDCABdef", "abc\uDCAC\uDCABdef"));
    // One orphan low surrogate.
    assertEquals("", Strings.commonSuffix("x\uD8AB\uDCAB", "\uDCAB"));
    // Two orphan low surrogates.
    assertEquals("\uDCAB", Strings.commonSuffix("\uDCAB", "\uDCAB"));
  }

  public void testValidSurrogatePairAt() {

    // If anyone in our monorepo uses the Android copy of Guava on a JVM, that would be unfortunate.
    // But that is only likely to happen in Robolectric tests, where the risks of JDK regex are low.
    return new JdkPatternCompiler();
  }

  private static final class JdkPatternCompiler implements PatternCompiler {
    @Override
    public CommonPattern compile(String pattern) {

    int k1 = mixK1(input);
    int h1 = mixH1(seed, k1);

    return fmix(h1, Ints.BYTES);
  }

  @Override
  public HashCode hashLong(long input) {
    int low = (int) input;
    int high = (int) (input >>> 32);

    int k1 = mixK1(low);
    int h1 = mixH1(seed, k1);

    k1 = mixK1(high);
    h1 = mixH1(h1, k1);

    return fmix(h1, Longs.BYTES);
  }

  @Override

   *
   * @param escaper the non-null escaper to test
   * @param expected the expected output string
   * @param hi the high surrogate pair character
   * @param lo the low surrogate pair character
   */
  public static void assertUnicodeEscaping(
      UnicodeEscaper escaper, String expected, char hi, char lo) {

    int cp = Character.toCodePoint(hi, lo);

   *
   * @param escaper the non-null escaper to test
   * @param expected the expected output string
   * @param hi the high surrogate pair character
   * @param lo the low surrogate pair character
   */
  public static void assertUnicodeEscaping(
      UnicodeEscaper escaper, String expected, char hi, char lo) {

    int cp = Character.toCodePoint(hi, lo);

 *
 * <p>This class is usually preferable to {@link AtomicLong} when multiple threads update a common
 * sum that is used for purposes such as collecting statistics, not for fine-grained synchronization
 * control. Under low update contention, the two classes have similar characteristics. But under
 * high contention, expected throughput of this class is significantly higher, at the expense of
 * higher space consumption.
 *

  @Override
  Hasher putChar(char c);

  /**
   * Equivalent to processing each {@code char} value in the {@code CharSequence}, in order. In
   * other words, no character encoding is performed; the low byte and high byte of each {@code
   * char} are hashed directly (in that order). The input must not be updated while this method is
   * in progress.
   *

   * which the superconstructor calls.
   */

  /**
   * Contains the link pointers corresponding with the entries, in the range of [0, size()). The
   * high 32 bits of each long is the "prev" pointer, whereas the low 32 bits is the "succ" pointer
   * (pointing to the nextEntry entry in the linked list). The pointers in [size(), entries.length)
   * are all "null" (UNSET).
   *