Topological sorting in PLSQL

For my testdata_ninja library, I recently created the field auto reference feature, where a value from one field can be used as an input to a generator for another field. Part of this feature involves parsing all columns and building a dependency list (Directed Acyclic Graph) sorting all columns correctly. Since everything in the library is build purely in plsql, I don't store anything in tables. So if my data is not in a table, I cannot use sql as one would normally do it. I couldn't find any code out there that did what I wanted, so like much of the other stuff I do, I had to build it myself.