[antlr-interest] Is this Recognizer optimization valid?

[mzukowski at bco.com]

You could do that but you still have to have guessing guards around
individual productions, of course.  And you still have to increment and
decrement the guessing state just as happens now because syntactic
predicates can be nested arbitrarily.

Just how much guessing is your code doing?  Some people overuse syntactic
predicates because they don't understand proper factoring of rules or they
don't think about the shortest syntactic predicate that will work.  But with
a truly ambiguous language you will have no choice but to use syntactic
predicates.

Monty

> -----Original Message-----
> From: Sander Mägi [mailto:sander at aqris.com]
> Sent: Tuesday, October 02, 2001 7:58 AM
> To: antlr-interest at yahoogroups.com
> Subject: Re: [antlr-interest] Is this Recognizer optimization valid?
> 
> 
> Couldn't the codegen actually generate methods like 'statement' and
> 'statementGuessing' and skip the if(inputStateGuessing ==0) 
> parts at all?
> 
> Probably C++ compilers do proper inlining and make it fast, but my
> experience shows that in java many things that should be 'naturally
> optimized' are not.
> 
> Sander
> 
> ----- Original Message -----
> From: "Ric Klaren" <klaren at cs.utwente.nl>
> To: <antlr-interest at yahoogroups.com>
> Sent: Tuesday, October 02, 2001 4:43 PM
> Subject: Re: [antlr-interest] Is this Recognizer optimization valid?
> 
> 
> > Hi,
> >
> > On Tue, Oct 02, 2001 at 04:40:34PM +0200, Sander Mägi wrote:
> > > null would give null pointer exception. The ASTpair's 
> root and child
> > > variables are still read for their content like returnAst =
> currentAst.root.
> >
> > Ack you're right. But in the codegen these could be guarded by an
> > (guessing != 0) check.
> >
> > Ric
> > --
> > 
> -----+++++****************************************************
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> -----
> >     ---- Ric Klaren ----- klaren at cs.utwente.nl ----- +31 53 
> 4893722  ----
> > 
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>


 

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