[antlr-interest] my brief thoughts on performance

doctlo-antlr at yahoo.com doctlo-antlr at yahoo.com
Thu Feb 24 17:14:23 PST 2005

On Thu, 24 Feb 2005 16:44:24 -0800, you wrote:

>Next, I agree that much can be done to increase speed by tailoring the 
>lexer methods like LA and so on to be suitable for your application.  
>Even in general I think much could be done.  I looked at it last year 
>when Sriram S. told me that he got a huge improvement, but I didn't see 
>an obvious way to be general and do what he did.  The conclusion I have 
>for 2.x is that you must rely on non-general user modifications to make 
>it go fast; i.e., you have to do the tweaks, but perhaps we can 
>summarize some useful tweaks.  Perhaps a quick change to the code 
>generators will allow caching of LA(i).

OK. I haven't been looking at the debate about LA closely and I don't
know the internals of Antlr generated code and the Antlr libraries
that well yet, but has anyone tried had tweaking code to memoise LA?

class Whatever
   private static Token cache["k"];
   public Token LA(int i)
       Token retval=cache[i];
           retval= LA_internal(i);
    return retval;
   public void consume()
      int i;

PS: My Java is not so hot either but should be good enough to get the
point across.

Thaddeus L. Olczyk        

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