But sorting on length will not do. A trivial and silly example, when the delimiters are abc and ab*c*, if you try ab*c* first, you'll never succeed on abc.

You could make an ordering if you can decide whether one regex will match everything another does. I doubt this is a decidable question for Perl regular expressions. It is for "normal" regular expressions, and, IIRC, undecidable for context free grammars. Perl regular expressions are hard to qualify in this sense, but even if it's theoretical possible, it's not going to be cheap, and hence the price would be high.

It's going to be a responsibility of the programmer to pass in the options in a logical order; just as already is required for alternations in regular expressions.

Abigail