Re: [lisp-snmp] [patch] CL-YACC support in ASN.1

[John F. <jf...@ms...>]

Dear Chun Tian,

"Chun Tian (binghe)" <bin...@gm...> writes:

> I've merged your patch in a quite different way:
>
> 1) Define a variable *asn.1-syntax* to hold all LALR syntax rules.
> 2) Convert your CL-YACC changes into loadable patch and put them in
> #p"ASN1:vendor;"
> 3) On LispWorks, still use PARSERGEN
> 4) On non-LispWorks, use your DEFPARSER-TO-YACC to convert *asn.1-
> syntax* into CL-YACC format.
>
> 5) The "eval-compile-asn.1" funtion haven't merged.
>
> I think it's beautiful way to made this big changes and only generate
> minimum diff to original code, but ... it seems that something goes
> wrong, either in CL-YACC patch side, or in DEFPARSER-TO-YACC. Can you
> find it?

I don't like this way.

Please don't do it like this.

The defparser-to-yacc function was a quick hack for one time use. It was
not designed to be used like this.

It is only luck that this particular grammar can be transformed by this
function. It is quite likely that more complex grammars cannot be
transformed. The function would have to be extended to support more
advanced grammars.

The reason I kept both grammars active, was so that you could test that
the transform was correct. That is the only reason. It is difficult to
make a general grammar translator. The function I made is not a general
grammar translator. It only works on simple grammars.

Having two different parser generators does not bring any benefits, as
far as I can see, and means that there is quite likely to be different
behaviour on different Lisps. Why do you want to keep using the
Lispworks generator?

I recommend having a transition period until Juliusz releases a new
version of cl-yacc, and then moving over to cl-yacc entirely.

PS. I have a working portable version of cdr-assoc in my personal
development tree of cl-irregsexp (the one in the released version is
borked). When I get the Internet at home I will push it to the cl.net
repo.

[...]