Parsing valid parent directories with regex

Question

Given the string a/b/c/d which represents a fully-qualified sub-directory I would like to generate a series of strings for each step up the parent tree, i.e.

Answer 1

Completely different answer without reversing string.

(?<=((?:\w+(?:/|$))+(?=\w)))

This matches

a/
a/b/
a/b/c/

but you have to use C# which use variable lookbehind