persistable sclass HuffmanByteArray is BitIO {

  settable byte[] data;

  gettable int[] histogram;

  gettable HuffmanTreeMaker tm;

  gettable new HuffmanTree tree;

  // options

  settable bool startWithMagicCode;

  settable S magicCode = "HUF1";

  *(byte[] *data) {}

  public void readWrite(BitHead head) {

    if (head.writeMode() && histogram == null) {

      histogram = byteHistogramArray(data);

      tm = new HuffmanTreeMaker;

      tm.importByteHistogram(histogram);

      tree = tm!;

    }

    // Part 1 (magic code)

    if (startWithMagicCode)

      head.exchangeASCII(magicCode);

    // Part 2 (Huffman character tree)

    tree.readWrite(head);

    // Part 3a (size)

    new VariableSizeUIntForBitHead().chunkSize(3).readWrite(head, -> data.length, size -> data = new byte[size]);

    //print("length " + data.length);

    // Part 3 (text)

    if (head.writeMode()) {

      fOr (b : data)

        tree.writeCharacter(b, head);

    }

    if (head.readMode()) {

      for i over data: {

        if (head.isEOF()) break;

        data[i] = toUByte(tree.readSymbol(head));

      }

    }

  }

  byte[] get() { ret data; }

  // update selfType

  public selfType fromByteArray(byte[] data) { BitIO.super.fromByteArray(data); this; }

  public selfType load(byte[] data) { BitIO.super.load(data); this; }

}