If you allow generating a regular expression based on string length, you can validate any computable language with a regular expression. It's trivial to just ru

If you allow generating a regular expression based on string length, you can validate any computable language with a regular expression. It's trivial to just run a solver on all strings of that length and or the accepted ones together. > What I suspect you might not be able to validate is that in a regex, while [a-z] is valid, [z-a] is not. It's fairly trivial to validate things like a-z being valid in a character class while z-a isn't. There are only finitely many legal ranges. You can just list them all, like \[(a-a|a-b|a-c|...|z-z)\].