Re: Reverse engineering regular expressions

[bsb]

Generating regex strings with a regex

Or with Rexexp::Genex:

perl -MRegexp::Genex=:all -le 'print for strings(qr/(.*)test(.*)/)'
3'e3''test
3'e3'test~
3'e3'test
3'e3testÿÌ
3'e3testÿ
3'e3test
3'etest
3'etest
3'etest
3'etest
3'testÌeÿ
3'testÌe
3'testÌe
3'testÌ
3'test
3test~
3test
test

[davido]

But what has that gotten you? At best, a contrived minimal slice of an infinite set. Where, for example, is "asdf;laksjfd;alksjaewraefsdtest134qwefalskdfjaeraf;" (another minimal slice of infinity).

[bsb]

I didn't have time to wait for that one. :)

You are right, of course. However, sometimes a slice of an infinite set is enough, say for testing or debugging. Also, regexes with only small characater classes and finite quantifiers do produce useful and complete results.

Dominus' book gives you an infinite stream of the matching strings, ordered by length. Still quite a wait in your case.