I would suggest breaking this down as follows:
- Write a parser that transforms a generic ADD RULE statement into a useful data object. This could just be a hash/hashref or an object (see Moose) if you want more functionality. This will allow you to more easily determine if objects have similar content.
- Read in the full rule set and treat it one rule at a time. This is definitely a TIMTOWTDI moment. I would enable slurp mode (local $/;, see $/ in perlvar) and then split the input into blocks and iterate over them (for (split /\n(?=ADD RULE$)/m) {...}), stashing the parsed objects into an array for later comparison. You could easily accomplish this a number of different ways.
This should give you plenty to get started.
