I was reading the venerable "How to Find or Validate an Email Address [using Regex]", and I came across the following statement at the bottom of the page:
[A] true regular language cannot enforce a length limit and disallow consecutive hyphens at the same time.
This seems wrong to me.
I feel like if the length of a string is bounded ahead of time, you should be able to write a DFA which processes pretty much any rule on the input string, as you can just create $n$ states from the most recent states, where $n$ is the number of letters in the alphabet, repeating for the maximal length of the input string?
If this reasoning is wrong, can someone point me in the right direction?