Re: [m-users.] parsing, seeking advice on simple combinator project and also operators.

Volker Wysk <[email protected]> Sat, 29 Oct 2022 19:53:42 +0200

Newsgroups	gmane.comp.lang.mercury.general
Message-ID	<[email protected]>

Hi

Here's a parser combinator for you, using DCG syntax:


:- pred repeatmax0(pred(T, list(char), list(char)), 
                   list(T), 
                   list(char), list(char)).
:- mode repeatmax0(pred(out, in, out) is det,     out, in, out) is det.
:- mode repeatmax0(pred(out, in, out) is semidet, out, in, out) is det.
:- mode repeatmax0(pred(out, in, out) is multi,   out, in, out) is multi.
:- mode repeatmax0(pred(out, in, out) is nondet,  out, in, out) is nondet.

repeatmax0(Pars, Values) -->
    ( if   Pars(Val)
      then { Values = [Val|Vals] },
           repeatmax0(Pars, Vals)
      else { Values = [] }
    ).


It repeats applying a parser (Pars) as often as possible and collects the
results in a list (Values).

Bye
Volker

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