Re: Retrieving the string name of token

[Hans Aberg]

On 7 Mar 2006, at 04:02, Frans Englich wrote:

> Let's say I've declared the following token:
>
> %token IMPORT_MODULE                        "import module"
>
> Is it somehow possible to in code retrieve "import module" when  
> given the
> IMPORT_MODULE define/enum? Is there a public function somewhere for  
> that? I
> want to keep the descriptions centralized.

Bison writes (I think) an array into the parser with those names.  
Check output parser source.

>                         ***
>
> Also,

Please keep one topic per post, with descriptive subject for each.

> sometimes I really feel like writing rules like this:
>
> Rule: (A | B) C D
>
> Which would allow A C D or B C D. What is the reason to that such  
> constructs
> are not possible?

Simply because nobody has implemented it. I think some grads at  
Berkeley made a Bison version with such constructs.

> I think it would be possible if for example one ensured that A and  
> B had the
> same types, or disallowed token values to be retrieved($N) if the  
> types were
> incompatible.
>
> Yes, I know the same can be expressed this way:
>
> Rule: AorB C D
>
> AorB: A
> | B
>
> I also guess that if Bison support the imaginary form above(if  
> that's at all
> possible) it would rewrite into this latter, valid form.
>
> My point being I find the first form much more readable.

One just expands it using standard rewrites (which I have posted here  
before). In Bison, one would also enable the addition of suitable  
actions.

  Hans Aberg