sdm@cs.brown.edu (Scott Meyers) (04/01/91)
Archive-name: languages/parsers/bison++/1991-03-29
Archive: wilbur.stanford.edu:/pub/bison++-1.02.tar.Z [36.14.0.30]
Original-posting-by: sdm@cs.brown.edu (Scott Meyers)
Original-subject: Multiple Lexers/Parsers (Summary)
Reposted-by: emv@msen.com (Edward Vielmetti, MSEN)
I received a number of replies regarding my request for information on
generating multiple lexers and parsers to run in a single application. It
seems that a number of people have run up against this problem, but there
doesn't seem to be a simple solution to it, i.e., there isn't any widely
available software that generates the code more or less automatically.
In theory, what should work is combining the OMA lexer-generator from
Oregon State University with the bison++ parser generator from Stanford.
OMA is said to generate C++ class definitions containing lexers, and one
person wrote to say it worked well for him. However, I couldn't get it to
compile here. According to the README file, the current OMA is "a very
primitive pre-release version." OMA is ftp-able from cs.orst.edu in the
directory pub/budd/oma.
Bison++ generates C++ class definitions from yacc-like input files, and it
seems to work just fine, thanks to some very speedy fixes by Larry
Augustin, to whom I am greatly indebted. Bison++ is ftp-able from
wilbur.stanford.edu in the pub directory.
A couple of people mentioned modifications they'd made to byacc. I don't
have access to byacc, so I don't know anything about it, and since I'm
happy with bison++, I didn't look into byacc very much. In conjunction
with byacc, flex was also usually mentioned, but our version of flex
(2.3.6) doesn't generate classes, or at least the documentation doesn't say
anything about it generating classes (I didn't actually try it). Flex
will, however, generate code that can be compiled with a C++ compiler.
Our beta versions of Sun's lex++ and yacc++ are similar to our version of
flex in that they generate C++ code, but they don't generate classes:
you're still stuck with a single yylex and a single yyparse.
Finally, I received word of a commercial product called Yacc++, as follows:
We have a commercial product called Yacc++, which can generate multiple
lexers and parsers. It generates lexer and parser "objects" in
standard C. They are objects in the sense that the lexer/parser
generator implements (multiple) inheritance of grammars and the
resulting lexer and parser objects support dynamic binding and
polymorphism--lexers and parsers can be configured to communicate in
any pairings at runtime.
Chris Clark
Compiler Resources, Inc. voice: (508) 435-5016
3 Proctor Street fax: (508) 435-4847
Hopkinton, MA 01748
What I'm currently doing is using lex++ and bison++, and hoping that I can
eventually get OMA to work. In the meantime, I'm writing my lexers/parsers
separately and testing them in different programs. With any luck, by the
time I am confident that they work correctly, either OMA will work or I'll
have come up with some other brilliant solution to the lexing problem.
By the way, I also found the need to perform a fair amount of makefile
magic to get things to build automatically, but that's not too surprising
considering that I'm combining software from AT&T (C++ compiler), Gnu
(bison++), and Sun (lex++ beta).
Scott
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