Hi Sriram:

we have been very pleased with JavaCC and use it extensively in our work.

I would like to complement Doug's reference with one from the pre-www days:

@BOOK{hop-ull:aut,
AUTHOR = "John E. Hopcroft and Jeffrey D. Ullman",
TITLE = "Introduction to Automata Theory, Languages, and Computation",
PUBLISHER = "Addison-Wesley",
YEAR = "1979"
}

Pages 88 and 89 contains explanation and an efficient algorithm
for eliminating useless symbols.

Along the same line I would like to mention that it would be very useful
for JavaCC users to know in which of _seven_ fundamental categories
their grammar falls. The Venn diagram for 11 categories is in my book
on page 372:

ftp://ftp.ccs.neu.edu/pub/people/lieber/book/aoos.PDF
http://www.ccs.neu.edu/research/demeter/biblio/dem-book.html

We have implemented a very effcient semantic checker for grammars which
distinguishes between the 7 categories (in C++ for Demeter/C++)
and the source code is on the web. It is only for 7 since
ambiguity is undecidable. Let me know if you need a pointer to the source
code.

Best regards,
-- Karl

From dougo@ccs.neu.edu Tue Jun 23 18:29:52 1998
From: Doug Orleans <dougo@ccs.neu.edu>
To: Sriram Sankar <sriram.sankar@metamata.com>
cc: dougo@ccs.neu.edu, lieber@ccs.neu.edu
Subject: Re: useless symbols

It is possible
to determine (in polynomial time even) whether each production in a
grammar can ever be used in parsing any finite string.  See, e.g.,
http://watson2.cs.binghamton.edu/~lander/cs373/1997_cs373N11.html

--Doug