[antlr-interest] Error recovery during list assembly

[Johannes Luber]

Brent Yates schrieb:
> For the following rule:
> 
> list
>     :   BEGIN item* END
>     ;
>    
> I would like to be able to recovery from tokens which are not valid 
> items and not the END literal in such a way that the item list assembly 
> keeps going.  From inspection of the currently generated code (3.1b2, C 
> target) the parser will check to see if the next token matches one of 
> the expected tokens for item.  If it does, it calls the item rule, if 
> not, it drops out of the item loop and tries to match the END literal.  
> If the end match fails then a normal single token delete/insert recovery 
> is tried.  The parser is expecting the END literal though, not more 
> items, and I don't
> see a way to get back into the items loop.
> 
> It seems that I need the recovery to happen in the item rule function, 
> but the error is not detected in the item rule - it is detected in the 
> check for END.
> 
> Is there a way to structure the rule to help this situation or is there 
> a manual way to code via actions or overrides a way to recover from 
> these sorts of input errors?
> 
> Thanks!
> 
> Brent Yates

You are describing a situation which mention Ter on his blog once. IIRC 
then ANTLR doesn't handle this situation itself. I don't know if you can 
overwrite this behaviour yourself. :(

Johannes