checkArgument(
        !separatorPattern.matcher("").matches(),
        "The pattern may not match the empty string: %s",
        separatorPattern);

    return new Splitter(
        (splitter, toSplit) -> {
          CommonMatcher matcher = separatorPattern.matcher(toSplit);
          return new SplittingIterator(splitter, toSplit) {
            @Override

  private static void checkTryParse(String input) {
    Double expected = referenceTryParse(input);
    assertThat(Doubles.tryParse(input)).isEqualTo(expected);
    if (expected != null && !Doubles.FLOATING_POINT_PATTERN.matcher(input).matches()) {
      // TODO(cpovirk): Use SourceCodeEscapers if it is added to Guava.
      StringBuilder escapedInput = new StringBuilder();
      for (char c : input.toCharArray()) {
        if (c >= 0x20 && c <= 0x7E) {

    }

    /**
     * Creates a path matcher function for path mapping.
     *
     * @param matcher the regex matcher
     * @param replacement the replacement string
     * @return the path matcher function
     */
    public BiFunction<String, Matcher, String> createPathMatcher(final Matcher matcher, final String replacement) { // for PathMapping

      expectFailure(platformMatches(LOOM_PROPERTY))
    }

    private fun expectFailure(
      versionMatcher: Matcher<out Any>,
      failureMatcher: Matcher<out Any> = anything(),
    ) {
      versionChecks.add(Pair(versionMatcher, failureMatcher))
    }

    fun platformMatches(platform: String): Matcher<Any> =
      object : BaseMatcher<Any>() {
        override fun describeTo(description: Description) {

            throw new IllegalStateException("Malformed distributionUrl line: " + distributionUrl);
        }
        String url = distributionUrl.substring(idx + 1).trim();

        Matcher m = WRAPPER_VERSION_EXTRACT.matcher(url);
        if (!m.matches()) {
            throw new IllegalStateException("Could not extract wrapper version from distributionUrl: " + url);
        }
        return m.group(1);
    }

        return Arrays.stream(values).map(s -> {
            final Matcher matcher = VERSION_PREFIX_PATTERN.matcher(s);
            if (!matcher.matches()) {
                return s;
            }
            final int v = Integer.parseInt(matcher.group(1));
            if ("-".equals(matcher.group(2))) {
                if (version >= v) {
                    return matcher.group(3);
                }
            } else if (v == version) {

    bitSet.clear(0);
    bitSet.clear(1);
    matcher = useNew ? CharMatcher.whitespace() : OLD_WHITESPACE;
    teststring = newTestString(new Random(1), bitSet, percentMatching);
  }

  @Benchmark
  public int countIn(int reps) {
    int result = 0;
    CharMatcher matcher = this.matcher;
    String teststring = this.teststring;
    for (int i = 0; i < reps; i++) {
      result += matcher.countIn(teststring);
    }
    return result;

    bitSet.clear(0);
    bitSet.clear(1);
    matcher = useNew ? CharMatcher.whitespace() : OLD_WHITESPACE;
    teststring = newTestString(new Random(1), bitSet, percentMatching);
  }

  @Benchmark
  public int countIn(int reps) {
    int result = 0;
    CharMatcher matcher = this.matcher;
    String teststring = this.teststring;
    for (int i = 0; i < reps; i++) {
      result += matcher.countIn(teststring);
    }
    return result;

import com.google.common.annotations.GwtCompatible;

/**
 * The subset of the {@link java.util.regex.Matcher} API which is used by this package, and also
 * shared with the {@code re2j} library. For internal use only. Please refer to the {@code Matcher}
 * javadoc for details.
 */
@GwtCompatible
abstract class CommonMatcher {
  public abstract boolean matches();

  public abstract boolean find();

  public abstract boolean find(int index);

                    .findFirst()
                    .orElseThrow(() -> new IOException("Can't find package definition in file " + file));
                Matcher matcher = pattern.matcher(packageLine);
                if (matcher.find()) {
                    return matcher.group(1);
                } else {
                    throw new IOException("Can't extract package name from file " + file);
                }
            }