I, too, am interested.   I agree, based on this further explanation, that my original suggestion of subs could become unmanageable in the use-case that you describe.   I graciously withdraw my suggestion . . .

The notion of building a Regex, as BrowserUK originally suggests below and as poj took and ran-with a little later on, is probably the right balance between readability and flexibility.   (All now liberally sprinkled with up-vote pixie-dust...)