[ANSI-Smalltalk] Fwd: About using SDF in Smalltalk standardization effort

[Bruce Badger]

Dear all,

My rather moribund Step to capture the Smalltalk syntax as defined in
the existing ANSI standard has received a massive boost! :-)

At ESUG Tijs van der Storm gave a talk about the Meta Environment
which is a tool for working with language grammars.  As part of his
talk Tijs showed the syntax of Smalltalk which he had put together on
the basis of earlier work by Alan Lovejoy.

Tijs explains all this in his message below.  I have another weekend
away coming up, but I'll be taking Tijs' work as the basis for the
Step document and getting a version out as soon as I can.

All the best,
    Bruce

---------- Forwarded message ----------
From: Tijs van der Storm <storm at cwi.nl>
Date: 2008/9/1
Subject: About using SDF in Smalltalk standardization effort
To: bbadger at openskills.org


Dear Bruce,

Thanks for showing an interest in using SDF in standardizing
Smalltalk. I would be glad to be of any help. Could you describe your
plans for the syntax definition of (the current ANSI standard of)
Smalltalk? I believe this will be one of the STEPs?

Attached you will find an SDF definition of the current version of
ANSI-Smalltalk. It is based on the EBNF grammar found on
http://chronos-st.blogspot.com/2007/12/smalltalk-in-one-page.html. I
did not check with the (draft) standard, yet. I provide it here just
to give you an impression. Although I have used this grammar to
successfully parsed snippets of Smalltalk, it probably contains
errors, and may be ambiguous. Alan Lovejoy (Chronos blog), also
states:

To resolve any ambiguities that may arise due to the absence of
optional whitespace, lower-numbered production rules take precedence
over higher-numbered production rules. The ambiguity issue is normally
taken care of by having production rules 1 through 38 handled by the
lexical analyzer, but having the remainder (production rules 39
through 67) handled by the parser.

Since lexing and and parsing is integrated in SDF, it *may* be so that
these issues do not arise, but I'm not sure. Again, we would be glad
to be of any help in supporting your standardization efforts using
this grammar. We are ourselves interested in high-quality grammars of
many computer languages. The Smalltalk grammar would present a very
nice case study for assessing grammar quality (e.g. ambiguity etc.).

The grammar can be used to parse Smalltalk using the ASF+SDF
Meta-Environment (I showed an example on my slides), which can be
downloaded from (http://www.meta-environment.org). If you need any
help, let me know.

Kind regards,

Tijs van der Storm


P.S. I currently provide this grammar as is. We will probably release
it as part of our software transformation system
(http://www.meta-environment.org). The license will then be BSD style.
If this poses problems, we will have to arrange something.




--
Researcher Centrum voor Wiskunde en Informatica (CWI)
Coordinator Master of Software Engineering Universiteit van Amsterdam

Dr. Tijs van der Storm @ Centre for Mathematics & Computer Science CWI
Office: M335 | Phone: +31 (0)20 5924164 | Address: Kruislaan 413
P.O. Box 94079 | Postal code: 1090 GB | Amsterdam, The Netherlands
s



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