johnl@ima.UUCP (Compilers mailing list) (07/02/86)
I am trying to write a few retargetable code generators this summer,
and I thought it would be real helpful if I had an attribute grammar
parser generator to help.
Specifically, I am looking for a YACC look-a-like that will allow a
boolean variable to be associated with each production. At generation
time there will be several ambiguous productions that will be resolved
at run time by the boolean flags. This will enable/disable productions
based upon semantic information.
I have half an inkling to hack YACC to do this. But before I go off on
a tangent, can someone point me towards an existing program/system that
will do what I have described?
I am not certain, but I suspect that a reasonable price for such a system
can be accomodated.
Jon Loeliger jdl@Purdue.ARPA
Dept. of Computer Science jdl@mordred.cs.purdue.edu
Purdue University {ihnp4, decvax, ucbvax,...}!purdue!jdl
W. Lafayette, IN 47907
(317) 494-6180
[I did something like this in about 1978 with plain old ordinary yacc. The
trick was to invent a bunch of fake tokens, and to write the ambiguous
productions like this:
thing ::= fake1 prod1 | fake2 prod2 | ...
The lexer returned a fake token at appropriate times to guide the parser.
It was the only way I could figure to parse Fortran, and it worked. -John]
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