Re: [cedet-semantic] Is there a wisent analog to Bison %empty non-empty rule?

[Eric L. <er...@si...>]

Hi Christian,

Using %prec, etc doesn't occur much in Wisent grammars because the usual 
use case is to generate tags, and not evaluate code that requires 
precedence.  If your goal is to just generate tags, there is a good 
chance you can just ignore the %prec pieces of the rule.  If the 
precedence is not used in expressions used after an equal, then you may 
be able to just delete the whole rule backup_fn_flags.

A quick read of bison %empty indicates it can be safely left out as 
well, so if you need to keep the rule, just delete %empty.

Hope this helps.
Eric

On 6/6/20 1:47 AM, Christian Johansson wrote:
> Hi!
> 
> I'm translating the PHP bison grammar to wisent and currently I'm stuck 
> at a rule that looks like this:
> 
> backup_fn_flags:
>      %prec PREC_ARROW_FUNCTION %empty { $$ = CG(extra_fn_flags); 
> CG(extra_fn_flags) = 0; }
> ;
> 
> The %prec symbol seems to work with Wisent but for the %empty I get the 
> message "wisent-parse-nonterminals: Symbol ‘%empty’ is used, but is not 
> defined as a token and has no rules"
> 
> Is it possible to solve this?
> 
> For empty %empty rules I just replace %empty with ;; empty\n but I don't 
> know what to do when there are other nonterminals in the rule
>