[HarfBuzz] Getting the number of Graphmes for a ligature

[Tom Hacohen]

Hey all,

I wonder, is there a way to get the number of Graphmes for a ligature?
I can just take the cluster index and the next cluster index (or in rtl
texts the other way around) and by that find the number of items,  but
this means I will have to handle the special case of just one ligature
in the text (because I won't have a next item).

Thanks,
Tom.