[antlr-interest] Assertion failure

[Ric Klaren]

togol machillan wrote:
> I get the following error messages at run time due to assertion failure. 
> 
>   col == 1
> Assertion failed: nb <= entries(), file c:\antlr-2.7.5\lib\cpp\antlr\circularqueue.hpp, line 59
> 
> Here col is a global integer variable which has the column number of the keyword after that rule is called. The rule which generates this message looks like
> 
> paragraph: keyword {col == 1} ...
>          ; 
> 
> keyword: t:"TITLE" {col = t->getColumn();}
>          |in:"IN-UNITS" {col = t->getColumn();} 
>          |data:"DATABANKS" {col = t->getColumn();}
>         ;
> 
> 
> The difficulty is that the assertion fails even when the keyword like TITLE
 > occurs in column 1. Can somebody please explain how to avoid this
 > assertion failure.

Could you send me a copy of the grammar that triggers this (if possible) 
preferably pruned down to a minimal example that triggers the problem 
together with the input? I'm short on time but I try to have a look.

 > Secondly, is there a better way of getting the column number in the
 > keyword rule without defining a label for every alternative literal.

keyword:    {col = LT(1)->getColumn();} t:"TITLE"
          |  {col = LT(1)->getColumn();} in:"IN-UNITS"
          |  {col = LT(1)->getColumn();} data:"DATABANKS"
         ;

Should probably work. (LT(1) refers to the first lookahead token)

Cheers,

Ric

> 
> Thank you all for your helpful suggestions to my previous queries.
> 
> Togol  
>