val element = WebPlatformUrlTestData()
        element.input = unescape(parts[i++])

        val base = if (i < parts.size) parts[i++] else null
        element.base =
          when {
            base == null || base.isEmpty() -> list[list.size - 1].base
            else -> unescape(base)
          }

        while (i < parts.size) {
          val piece = parts[i]

private fun Buffer.startsWith(prefix: Byte): Boolean = !exhausted() && this[0] == prefix

/**
 * Reads a double-quoted string, unescaping quoted pairs like `\"` to the 2nd character in each
 * sequence. Returns the unescaped string, or null if the buffer isn't prefixed with a
 * double-quoted string.
 */
@Throws(EOFException::class)
private fun Buffer.readQuotedString(): String? {
  require(readByte() == '\"'.code.toByte())

   * href="https://url.spec.whatwg.org/#url-code-points">many of these are accepted in modern
   * URLs</a>. (<a href="https://url.spec.whatwg.org/#path-state">If the escaper were to leave these
   * characters unescaped, they would be escaped by the consumer at parse time, anyway.</a>)
   * Additionally, the escaper escapes the slash character ("/"). While slashes are acceptable in

import org.jspecify.annotations.Nullable;

/**
 * A {@code UnicodeEscaper} that escapes some set of Java characters using a UTF-8 based percent
 * encoding scheme. The set of safe characters (those which remain unescaped) can be specified on
 * construction.
 *
 * <p>This class is primarily used for creating URI escapers in {@link UrlEscapers} but can be used

   * href="https://url.spec.whatwg.org/#url-code-points">many of these are accepted in modern
   * URLs</a>. (<a href="https://url.spec.whatwg.org/#path-state">If the escaper were to leave these
   * characters unescaped, they would be escaped by the consumer at parse time, anyway.</a>)
   * Additionally, the escaper escapes the slash character ("/"). While slashes are acceptable in

 * code point. An additional safe range is provided that determines whether code points without
 * specific replacements are to be considered safe and left unescaped or should be escaped in a
 * general way.
 *
 * <p>A good example of usage of this class is for HTML escaping where the replacement array

        if (result.indexOf('\"') >= 0) {
            final Matcher m = QUOTE_REPLACE_PATTERN.matcher(original);
            if (m.matches()) {
                result = m.group(1);
            }

            // Unescape
            if (result.indexOf(ESCAPED_QUOTE) >= 0) {
                result = result.replace(ESCAPED_QUOTE, "\"");
            }
        }

        return result;

    }

    /**

    try {
      e.escape((String) null);
      fail("Escaping null string should throw exception");
    } catch (NullPointerException x) {
      // pass
    }

    // All URL escapers should leave 0-9, A-Z, a-z unescaped
    assertUnescaped(e, 'a');
    assertUnescaped(e, 'z');
    assertUnescaped(e, 'A');
    assertUnescaped(e, 'Z');
    assertUnescaped(e, '0');
    assertUnescaped(e, '9');

    assertEquals("string with spaces", spaceEscaper.escape("string with spaces"));
  }

  /** Tests that if we add extra 'safe' characters they remain unescaped */
  public void testCustomEscaper() {
    UnicodeEscaper e = new PercentEscaper("+*/-", false);
    for (char c = 0; c < 128; c++) {
      if ((c >= '0' && c <= '9')
          || (c >= 'a' && c <= 'z')

    assertEquals("string with spaces", spaceEscaper.escape("string with spaces"));
  }

  /** Tests that if we add extra 'safe' characters they remain unescaped */
  public void testCustomEscaper() {
    UnicodeEscaper e = new PercentEscaper("+*/-", false);
    for (char c = 0; c < 128; c++) {
      if ((c >= '0' && c <= '9')
          || (c >= 'a' && c <= 'z')