[antlr-interest] Re: optional rule confusion

Lubos Vnuk lubos.vnuk at rts.at
Wed Mar 3 05:38:38 PST 2004


I think you can get some information from a similar thread 
titled: "Problem with x: (A)(B)? ; "

Regards,
Lubos.

--- In antlr-interest at yahoogroups.com, Igor Fedorenko 
<ifedorenko at r...> wrote:
> I must be missing something really simple, but I cannot get antlr 
> generate reasonable parser for javadoc-like java method names (like 
> com.something.MyClass#method).
> 
> Here is what my parser rule looks like
> 
>      protected javaname: ID (DOT ID)* (POUND ID)?
> 
> And here is what antlr generates for the last part
> 
>      switch ( LA(1)) {
>      case POUND:
>        {
>        match(POUND);
>        m = LT(1);
>        match(ID);
>        break;
>        }
>      case EOF:
>        {
>        break;
>        }
>      default:
>        {
>        throw new NoViableAltException(LT(1), getFilename());
>        }
>      }
> 
> 
> Why would antlr generate NoViableAltException for something which 
is 
> optional?
> 
> 
> Regards,
> Igor Fedorenko



 
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