[antlr-interest] Tracking Character Position in antlr3

[Terence Parr]

On Jan 19, 2007, at 7:43 AM, Edson Tirelli wrote:

>
>    Hello All,
>
>    I think this is probably a recurring frequent question, but the  
> answers I was able to find, both in the FAQ( http://www.jguru.com/ 
> faq/view.jsp?EID=550800 ) and the list archives seems to refer to  
> antlr 2.x version. So, here we go again:
>
>    We have a parser generated by antlr 3. We also have an IDE built  
> over eclipse. We have a requirement from the IDE guys that the  
> parser must provide location within the source files as character  
> position from the beggining of the file, instead of line/columns.
>    Looking through antlr source code, it seems that CommonToken has  
> this information encoded as "start" and "stop" indexes and you can  
> get them through methods: getStartIndex() and getStopIndex(). I  
> developed some unit tests (hardcoding class casts from Token to  
> CommonToken) and these attributes are consistent throughout the  
> parsing.
>
>    So, my questions:
>
> 1) Is there any reason for these methods to not be exposed in the  
> Token interface? In other words, can they be exposed in the Token  
> interface implemented by CommonToken? This would avoid the nasty  
> class casts...

A minimal token doesn't need those...can just answer getText.

I can see your need though.

> 2) If not, do you see any reason for me to not do the casts and get  
> the info from the CommonToken class?

That is ok.

> 3) Is there any other better alternative way of doing it?

Not at the moment...we could extend Token, but it's getting complex.

Ter