* here would have no significance to end users, who would be forced to conform to the signature
   * used in FilenameFilter.)
   */
  @Override
  public boolean accept(File dir, String fileName) {
    return pattern.matcher(fileName).matches();
  }

  /** Equivalent to {@code putByte(b ? (byte) 1 : (byte) 0)}. */
  @CanIgnoreReturnValue
  @Override
  Hasher putBoolean(boolean b);

  @CanIgnoreReturnValue
  @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

  }

  private static final class JdkMatcher extends CommonMatcher {
    final Matcher matcher;

    JdkMatcher(Matcher matcher) {
      this.matcher = Preconditions.checkNotNull(matcher);
    }

    @Override
    public boolean matches() {
      return matcher.matches();
    }

    @Override
    public boolean find() {
      return matcher.find();
    }

    @Override
    public boolean find(int index) {

  private static final PatternCompiler patternCompiler = loadPatternCompiler();

  private Platform() {}

  static CharMatcher precomputeCharMatcher(CharMatcher matcher) {
    return matcher.precomputedInternal();
  }

  static <T extends Enum<T>> Optional<T> getEnumIfPresent(Class<T> enumClass, String value) {
    WeakReference<? extends Enum<?>> ref = Enums.getEnumConstants(enumClass).get(value);

  @Override
  @CanIgnoreReturnValue
  public Hasher putLong(long l) {
    scratch.putLong(l);
    return update(Longs.BYTES);
  }

  @Override
  @CanIgnoreReturnValue
  public Hasher putChar(char c) {
    scratch.putChar(c);
    return update(Chars.BYTES);
  }

  public final Hasher putShort(short s) {
    buffer.putShort(s);
    munchIfFull();
    return this;
  }

  @Override
  @CanIgnoreReturnValue
  public final Hasher putChar(char c) {
    buffer.putChar(c);
    munchIfFull();
    return this;
  }

  @Override
  @CanIgnoreReturnValue
  public final Hasher putInt(int i) {
    buffer.putInt(i);
    munchIfFull();
    return this;

    hasher.putLong(0x0807060504030201L);
    hasher.assertBytes(new byte[] {1, 2, 3, 4, 5, 6, 7, 8});
  }

  public void testChar() {
    TestHasher hasher = new TestHasher();
    hasher.putChar((char) 0x0201);
    hasher.assertBytes(new byte[] {1, 2});
  }

  public void testString() {
    Random random = new Random();
    for (int i = 0; i < 100; i++) {
      byte[] bytes = new byte[64];

    HashCode unused = sink.hash();
    sink.assertInvariants(8);
    sink.assertBytes(new byte[] {1, 2, 3, 4, 5, 6, 7, 8});
  }

  public void testChar() {
    Sink sink = new Sink(4);
    sink.putChar((char) 0x0201);
    HashCode unused = sink.hash();
    sink.assertInvariants(2);
    sink.assertBytes(new byte[] {1, 2, 0, 0}); // padded with zeros
  }

  public void testString() {
    Random random = new Random();

  }

  private static final class JdkMatcher extends CommonMatcher {
    final Matcher matcher;

    JdkMatcher(Matcher matcher) {
      this.matcher = Preconditions.checkNotNull(matcher);
    }

    @Override
    public boolean matches() {
      return matcher.matches();
    }

    @Override
    public boolean find() {
      return matcher.find();
    }

    @Override
    public boolean find(int index) {

final class Platform {
  static CharMatcher precomputeCharMatcher(CharMatcher matcher) {
    // CharMatcher.precomputed() produces CharMatchers that are maybe a little
    // faster (and that's debatable), but definitely more memory-hungry. We're
    // choosing to turn .precomputed() into a no-op in GWT, because it doesn't
    // seem to be a worthwhile tradeoff in a browser.
    return matcher;
  }

  static String formatCompact4Digits(double value) {