[Question] How do I combine these parsers?

Let’s assume I have a Group 1 of parser a,b,c and d and Group 2 of parser w,x,y and z. I would like to combine these parses so that the resulting parser would parse any combination of parsers from group 1 and exactly 1 parser from group 2 in any order.

Is this possible?

It is quite possible that I’m attacking the problem from a wrong angle (XY-problem), here is what I’m really trying to solve.

I’d like to parse a command line switch that starts with - or / and then a number of options follows for example -abwdc among these options there could be as many as desired binary ones (that is a,b,c or d, that do not require a parameter to follow) but only one that requires a parameter (w,x,u or z). The options can be specified in any order.

[jzabroski]

@AndrewSav I’m pretty thankful for your stream of conciousness. I was looking to see if anyone had implemented a command-line parser library using SuperPower, as the whole tokenization feature seems like it would allow for people to extend it with varying grammars. And the parser combinator feature would allow for nesting grammars.

[AndrewSav]

@jzabroski

Try only makes sense for built-in parsers for identifiers, reserved symbols, operators, and reserved operators (e.g. for future use). Arbitrary lookahead is not a good default, because it increases run-time cost and makes analyzing performance of parser combinator-based grammars more difficult.

An example would be helpful, otherwise it’s a bit too abstract. I’m sure there are examples, I just did not come across any in anything I’ve done so far with Superpower.

The risk of looking lookahead with Or is you could end up with ambiguous parse forest.

Superpower is never ambiguous. It always prefers the first valid match.

To provide some lookahead, the parser combinators I mentioned are oftened called lexeme parsers because they only require one lookahead.

Which parser combinators did you mention? I must have missed that.