bageler seems to be looking for something more complicated that that, I'm afraid - that would simply give

foo
->bar
->narf
-->trof
-->etc.
[download]

I don't know if this is possible without recursion...being lazy, I'd personally use a recursive "GetChildren($id)" routine which greps for the parent $id and pushes the returned list onto itself - terribly inefficient (as you'd be grepping the list for every element), but easier to code :)

Cheers,
Ben.