RDoc::RI::Store to RDoc::TopLevel?

I’m working with the RDoc API and I was able to use RDoc::TopLevel
without
much problem, but I recently decided it would be better if I could make
use
of a RDoc cache instead of regenerating the docs every time.
Unfortunately
using the RI::Store is no where near as convenient a RDoc::TopLevel --a
lot
of pieces have to completed such as CodeObject#comment.

So, is there any way to populate RDoc::TopLevel from an RDoc::RI::Store
?