[antlr-interest] Re: Request enhancement ANTLR

[Terence Parr]

Yeah, I guess I agree.  Let's just add a getFilename method to parser 
that accepts a token.  The problem is: what if k=2 and the tokens have 
different filenames?  Do you just choose the first filename?

Ter

On Tuesday, June 25, 2002, at 04:38  AM, Ric Klaren wrote:

> On Tue, Jun 25, 2002 at 08:42:24AM +0200, Silvain Piree wrote:
>>>> Why not implement setFilename/getFilename in class Token
>>>> exactly like setText/getText are currently?
>>>
>>> Makes sense to me...adding to list.
>>
>> That would indeed be the best solution .... with one problem:
>> it's not compatible with current implementations.
>>
>> The problem again is the error message (NoViableAlt) raised
>> by the parser. The generated parser uses the getFilename()
>> method of the Parser class to determine the current filename.
>>
>> When registering the filename with the token, the parser
>> class would have to get the filename from the token (e.g.
>> LT(1).getFilename() ).
>>
>> But that will only work when getFilename() is implemented
>> for Token. Otherwise it will fail ....
>>
>> That's why I suggested to define another getFilename()
>> method in the Parser class where you pass the current
>> token as parameter. Then the implementer can decide
>> where to get the current filename.
>
> I'd go for this last scheme anytime. It offers most possibilities for
> customization.
>
> IMHO Empty place holder methods are evil. (although you sometimes have 
> to
> be pragmatic :) )
>
> Btw I'd prefer adding extra things like this as examples and not as 
> default
> functionality. If we come to the conclusion though that some extra
> interfacing/hooks are necessary to implement this kindoff thing then we
> definitely should go for it.
>
>>     throw new NoViableAltException(...,
>>         LT(1).getFilename() != null?
>>             LT(1).getFilename() : getFilename() );
>
> I'd still go for the getFilename( Token t ) solution. It offers more
> flexibility.
>
> Cheers,
>
> Ric
> --
> -----+++++*****************************************************+++++++++-
> ------
>     ---- Ric Klaren ----- klaren at cs.utwente.nl ----- +31 53 
> 4893722  ----
> -----+++++*****************************************************+++++++++-
> ------
>   "I don't have anything against Java - it's the best damn 
> implementation
>               of UCSD Pascal ever released..." --- Larry Smith
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