}

        in 8..9 -> {
          id = source.readUtf8LineStrict().takeIf { it.isNotEmpty() }
        }

        in 10..12 -> {
          id = null // 'id' on a line of its own.
        }

        in 13..14 -> {
          type = source.readUtf8LineStrict().takeIf { it.isNotEmpty() }
        }

        in 15..17 -> {

    val buffer = Buffer()
    FileSystem.SYSTEM.read(pathForTests) {
      val length = readInt()
      buffer.write(this, length.toLong())
    }
    while (!buffer.exhausted()) {
      var publicSuffix = buffer.readUtf8LineStrict()
      if (publicSuffix.contains("*")) {
        // A wildcard rule, let's replace the wildcard with a value.
        publicSuffix = publicSuffix.replace("\\*".toRegex(), "square")
      }

  val source: BufferedSource,
) {
  private var headerLimit = HEADER_LIMIT.toLong()

  /** Read a single line counted against the header size limit. */
  fun readLine(): String {
    val line = source.readUtf8LineStrict(headerLimit)
    headerLimit -= line.length.toLong()
    return line
  }

  /** Reads headers or trailers. */
  fun readHeaders(): Headers {
    val result = Headers.Builder()
    while (true) {

      var totalRuleBytes = 0
      var totalExceptionRuleBytes = 0

      fileSystem.source(publicSuffixListDotDat).buffer().use { source ->
        while (!source.exhausted()) {
          var rule: ByteString = source.readUtf8LineStrict().toRule() ?: continue

          if (rule.startsWith(EXCEPTION_RULE_MARKER)) {
            rule = rule.substring(1)
            // We use '\n' for end of value.
            totalExceptionRuleBytes += rule.size + 1