val type: Int,
  ) : MappedRange {
    val b1: Int
      get() =
        when (type) {
          TYPE_IGNORED -> 119
          TYPE_VALID -> 120
          TYPE_DISALLOWED -> 121
          else -> error("unexpected type: $type")
        }
  }

  data class Inline1(
    override val rangeStart: Int,
    private val mappedTo: ByteString,
  ) : MappedRange {
    val b1: Int
      get() {

          rangesBuffer.writeByte(range.b1)
          rangesBuffer.writeByte('-'.code)
          rangesBuffer.writeByte('-'.code)
        }
        is MappedRange.Inline1 -> {
          rangesBuffer.writeByte(range.b1)
          rangesBuffer.writeByte(range.b2)
          rangesBuffer.writeByte('-'.code)
        }
        is MappedRange.Inline2 -> {
          rangesBuffer.writeByte(range.b1)
          rangesBuffer.writeByte(range.b2)

   */
  internal const val B1_FLAG_MASK = 128

  /**
   * Byte 1 mask for the payload length.
   *
   * If this value is [PAYLOAD_SHORT], the next two
   * bytes represent the length. If this value is [PAYLOAD_LONG], the next eight bytes
   * represent the length.
   */
  internal const val B1_MASK_LENGTH = 127

 * that follows.
 *
 * b1
 * --
 *
 * This is either a mapping decision or the length of the mapped output, according to this table:
 *
 * ```
 *  0..63 : Length of the UTF-16 sequence that this range maps to. The offset is b2b3.
 * 64..79 : Offset by a fixed negative offset. The bottom 4 bits of b1 are the top 4 bits of the offset.

    val reservedFlag3 = b0 and B0_FLAG_RSV3 != 0
    if (reservedFlag3) throw ProtocolException("Unexpected rsv3 flag")

    val b1 = source.readByte() and 0xff

    val isMasked = b1 and B1_FLAG_MASK != 0
    if (isMasked == isClient) {
      // Masked payloads must be read on the server. Unmasked payloads must be read on the client.
      throw ProtocolException(

    sinkBuffer.writeByte(b0)

    var b1 = 0
    if (isClient) {
      b1 = b1 or B1_FLAG_MASK
    }
    when {
      dataSize <= PAYLOAD_BYTE_MAX -> {
        b1 = b1 or dataSize.toInt()
        sinkBuffer.writeByte(b1)
      }
      dataSize <= PAYLOAD_SHORT_MAX -> {
        b1 = b1 or PAYLOAD_SHORT
        sinkBuffer.writeByte(b1)
        sinkBuffer.writeShort(dataSize.toInt())
      }

  @ParameterizedTest
  @ArgumentsSource(FileSystemParamProvider::class)
  fun iterator(parameters: Pair<FileSystem, Boolean>) {
    setUp(parameters.first, parameters.second)
    set("a", "a1", "a2")
    set("b", "b1", "b2")
    set("c", "c1", "c2")
    val iterator = cache.snapshots()
    assertThat(iterator.hasNext()).isTrue()
    iterator.next().use {
      assertThat(it.key()).isEqualTo("a")
      it.assertValue(0, "a1")