CL-Yacc is a LALR(1) parser generator for Common Lisp, similar in spirit to AT&T Yacc, Berkeley Yacc, GNU Bison, Zebu, lalr.cl or lalr.scm.
CL-Yacc uses the algorithm due to Aho and Ullman, which is the one also used by AT&T Yacc, Berkeley Yacc and Zebu. It does not use the faster algorithm due to DeRemer and Pennello, which is used by Bison and lalr.scm (not lalr.cl).
CL-Yacc was originally written to compile a grammar for a superset of the C programming language (over 400 productions) that used to routinely parses thousands of lines of C code. (Since then, the code has been rewritten in Caml by Gabriel Kerneis — see CPC.)
CL-Yacc is portable ANSI Common Lisp, and has been successfully tested with CMUCL, SBCL, CLISP, CCL (OpenMCL), ECL and Lispworks. A minor tweak is needed to make it work under Genera. It does not work with GCL, which doesn't grok MAKE-LOAD-FORM.
Compile-time performance is reasonable, although not outstanding: on a Pentium-M at 1.4GHz, compiling a grammar with over 400 productions, 19 conflicts, and a lot of useless shifting takes 9s with CMUCL, 16s with Lispworks, 40s with CLISP. On the same machine, Zebu compiles that grammar in slightly over 4s with CMUCL.
CL-Yacc is complete as far as I am concerned: it does what I need, and does it fast enough on my machine. If you're using CL-Yacc, I'd be glad to hear about any features you might be missing.
Here's a list of things that I would like to do:
Here's a list of features that users have suggested but that I will probably not implement:
Read the CL-Yacc manual (PDF).
A full example of a parser written with CL-Yacc can be found in the file
the CL-Yacc distribution.
Please note: there are a number of patched versions of CL-Yacc floating around the net. Most of them are buggy. Please do not send me any bug reports unless you are sure that your sources come from me.
A tarball of the CL-Yacc sources should be available in my download area.
You can get my CL-Yacc tree by doing
git clone https://github.com/jech/cl-yacc
or browse the source on GitHub.
Back to my software page.