regular expression for a tree hierarchy string extraction

Question

suppose I have tree hierarchy string like this "/grand_parent/parent/child" (three level) or "/parent/child" (two level), "/child" (one level) and I tried "^(/[^/]*)" could extract the first level "/grand_parent", and wondering if I want to extract the first two levels if there exists, e.g.

• extract "/grand_parent/parent" for "/grand_parent/parent/child"
• extract "/parent/child" for "/parent/child"
• extract nothing for "/child"

what is the suggested regular expression?

Answer 1

Why not just ^/[^/]+/[^/]+?

Demo

Answer 2

My guess is that maybe you'd want to design an expression similar to:

^(?=\/[^\/]+\/[^\/]+)(\/[^\/]+\/[^\/]+)

not sure though:

Demo 1

which would work the same without the capturing group:

^(?=\/[^\/]+\/[^\/]+)\/[^\/]+\/[^\/]+

Demo 2

Escapings are just for the demos.