[antlr-interest] Context-Sensitive Follow Sets.. Bug?

[Jim Idle]

Perhaps this is another instance of not clearing the cached set?

Jim

> -----Original Message-----
> From: antlr-interest-bounces at antlr.org [mailto:antlr-interest-
> bounces at antlr.org] On Behalf Of Terence Parr
> Sent: Sunday, May 23, 2010 10:13 AM
> To: Sameh W. Zaky
> Cc: antlr-interest at antlr.org
> Subject: Re: [antlr-interest] Context-Sensitive Follow Sets.. Bug?
> 
> oh. it includes AND (not THE).  That *is* weird.
> 
> I'll look.
> Ter
> On May 23, 2010, at 10:06 AM, Sameh W. Zaky wrote:
> 
> > Here is the same message without formatting:
> >
> > ---------- Forwarded message ----------
> > From: Sameh W. Zaky <sameh.wz at gmail.com>
> > Date: Sun, May 23, 2010 at 3:29 PM
> > Subject: [antlr-interest] Context-Sensitive Follow Sets.. Bug?
> > To: antlr-interest at antlr.org
> >
> >
> > Hello everyone..
> > After reading the wiki article
> >
> http://www.antlr.org/wiki/display/ANTLR3/Custom+Syntax+Error+Recovery,
> > (thanks to Jim Idle, "Yes, you def. deserve a Masters too" ;-)) I
> went on
> > with developing my own example to test the
> > method: computeContextSensitiveRuleFOLLOW() (described here:
> >
> http://www.antlr.org/api/Java/classorg_1_1antlr_1_1runtime_1_1_base_rec
> ognizer.html#2b566e00e5d771f66dd4e29a4a27a1c4
> > )
> > The method works perfectly in all cases except in the case of zero or
> one,
> > Consider the following simple grammar:
> >
> >
> =======================================================================
> ======================
> >
> > start : animal (AND acClass)? service EOF;
> >
> > animal : (DOG | CAT );
> > service : (HARDWARE | SOFTWARE) ;
> > AND : 'and';
> > DOG : 'dog';
> > CAT : 'cat';
> > HARDWARE: 'hardware';
> > SOFTWARE: 'software';
> >
> > acClass
> > @init
> > {
> System.out.println(computeContextSensitiveRuleFOLLOW().toString());}
> >    :     ;
> >
> =======================================================================
> ==============
> >
> > Testing this grammar, with let's say input:
> > "dog and software",
> > the result in the console is:
> > "{4, 7, 8}" (which stands for tokens {THE, HARDWARE, SOFTWARE}),
> > although it is supposed to be:
> > "{7,8}" (which stand for tokens {HARDWARE, SOFTWARE} only).. Because
> after
> > acClass in start rule, if we get "the" as next token this will make
> the
> > input invalid..
> >
> > Any idea why this happens? Or how we can overcome it?
> > Thanks a bunch..
> > --
> > Sameh W. Zaky
> >
> >
> > Regards
> > --
> > Sameh W. Zaky
> >
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