// A is the user object associated with each mask (aka a "label").
// Each mask now has a multi-set of labels.
persistable sclass G22HashedMasks<A> is IG22MasksHolder<MultiSet<A>> {
  record noeq Mask(Image2B image) is IG22Mask<MultiSet<A>> {
    gettable new MultiSet<A> labels;
    int hash;
    
    public bool equals(O o) {
      if (o cast G22HashedMasks.Mask)
        ret hashCode() == o.hashCode()
          && binaryImagesIdentical(image, o.image);
      false;
    }
    
    public int hashCode() {
      if (hash == 0)
        hash = (int) hashImage2B(image);
      ret hash;
    }
    
    public Image2B image() { ret image; }
    public MultiSet<A> label() { ret labels; }
  }

  new CompactHashSet<Mask> masks;

  // creating a sub-holder
  *(L<IG22Mask<MultiSet<A>>> masks) {
    assertNempty(masks);
    maskSize(imageSize(first(masks).image()));
    fOr (mask : masks)
      this.masks.add(mask);
  }

  void addRegion(IImageRegion region, A label) {
    var mask = new Mask(regionToMaskImage(region));
    var existingMask = masks.find(mask);
    if (existingMask != null)
      mask = existingMask;
    else
      masks.add(mask);
    mask.labels.add(label);
    ghost_cache = null;
    certainty_cache = null;
    labels.add(label);
  }
  
  public L<Mask> masks() { ret asList(masks); }
  
  /*public LPair<Image2B, A> maskImagesWithLabels() {
    ret map(masks(), mask -> pair(mask.image, mask.labels));
  }*/
  
  !include early #1035854 // Masks holder Include
}