I've used sites like rubular.com to validate regular expressions. However, I'm wondering if there's anything out there that can evaluate the efficiency of a regular expression, i.e. show me how much (possibly unnecessary) backtracking is happening.
Does such a tool exist? I'm looking for one for Ruby in particular, but a "generic" might work, too.
To followup to my own question, I did find regex101.com, which has a debugger, and shows the number of steps involved.