[antlr-interest] Re: nice threads

Trey Spiva Trey.Spiva at embarcadero.com
Fri Jun 14 11:52:06 PDT 2002

Are you wanting to put these changes in 2.7.3 or writing a completely new
tool (AspectAntlr)?
> -----Original Message-----
> From: Terence Parr [mailto:parrt at jguru.com]
> Sent: Friday, June 14, 2002 11:59 AM
> To: antlr-interest at yahoogroups.com
> Subject: [antlr-interest] Re: nice threads
> Folks, Monty's email is not getting thru to the list...so here is a side
> thread to be weaved back in ;)
> Ter
> On Friday, June 14, 2002, at 07:15  AM, mzukowski at yci.com wrote:
> > Tree grammars for analysis.  Why wouldn't that work?  Do you really
> > need a
> > cyclic graph/network structure?
> Well, yes/no.  Turns out it is a tree now loring says ;)  You really
> need to convert a grammar to an NFA and then run a bounded k level
> NFA->DFA conversion to do the analysis (that is the algorithm I designed
> during my thesis).
> >
> > Is grammar subclassing still appropriate?
> I think it should be a function of the environment.  I.e, have a library
> of rules/grammars in your repository and then pick and choose stuff to
> grab to begin a new grammar.  A live push-forward-changes sort of thing
> is the same as inheritance ;) (I think they call that RCS) ;) ;)
> >
> > When I think about grammars and aspects I think actions--AspectANTLR
> > would
> > be the tool to weave your actions into your pure antlr grammars.  The
> > trick
> Oooooooohhhhhh.  Now THAT is the perfect explanation of what an Aspect
> is.  You don't want to modify a grammar physically just to add actions
> into the right spot!.  Oohhhh.
> > is how to specify the join points and the answer is???  Note that your
> > IDE
> > could still let you edit the actions as if they were attached to the .g
> > file, but in reality they don't have to be.  Nice for multipass tree
> > transforms and mixing C++ and Java output languages.
> Oh man...i think we're on to something.  AspectANTLR :)
> > I like the separation of antlr phases concept.  When I was digging into
> > lookahead to generate a lookahead dependency graph I was frustrated by
> > the
> > caching of lookahead info.  I don't remember exactly now but it seems
> > like
> > maybe I was trying to find the specific rules contributing to the
> > ambiguity
> > but sometimes when I got to the ambiguous rule the lookahead was already
> > computed without the backlinks to what rules contributed to the
> > lookahead
> > set.  Because you don't just want to know that a rule is ambiguous.
> > 50% of
> > the time it's because another rule called it and I was automating that
> > manual process of figuring out which caller rules were to blame.
> Yes, the cached lookahead information is useless for determining the
> paths in the grammar that are nondeterministic.  I would really like to
> have ANTLREclipse or whatever be able to highlight the paths for you.
> The caching is absolutely necessary for efficiency of this algorithm.
> Without it I cannot claim it is O(nk) where n is size of grammar.  But,
> a new version of antlr could avoid the caching when finding the problem
> spots.
> Ter
> --
> Co-founder, http://www.jguru.com
> Creator, ANTLR Parser Generator: http://www.antlr.org
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