Array size function / Rank

Hi, I've noticed that there is no RANK() or DENSE_RANK() function in KSQL. I tried to work around this by calling TOPKDISTINCT(col, static_int) and then returning the size of the array given by TOPKDISTINCT(), all within my relevant group by. Is there any workaround for this? I am not well versed in Java/Scala, so I could try writing this as a UDF, but I would prefer is there was a native solution for this. Cheers!