0 -> {
          // ;
          skipRestOfLine()
          IntRange(startCodePoint, startCodePoint)
        }
        1 -> {
          // '\n'
          IntRange(startCodePoint, startCodePoint)
        }
        2 -> {
          // '-'
          val endCodePoint = readHexadecimalUnsignedLong().toInt()
          skipRestOfLine()
          IntRange(startCodePoint, endCodePoint)
        }

internal const val TYPE_VALID = 6

private fun BufferedSource.skipWhitespace() {
  while (!exhausted()) {
    if (buffer[0] != ' '.code.toByte()) return
    skip(1L)
  }
}

private fun BufferedSource.skipRestOfLine() {
  when (val newline = indexOf('\n'.code.toByte())) {
    -1L -> skip(buffer.size) // Exhaust this source.
    else -> skip(newline + 1)
  }
}

/**
 * Reads lines from `IdnaMappingTable.txt`.