[pro] Is cl-yacc going to cut it?

[Matthew D. Swank]

I suppose this is only marginally related to common lisp, but everything
I'm talking about is written in common lisp.

I use cl-yacc for a lot of parsing, but one thing that has always seemed
harder than it needs to be is writing lexers to feed it. One thing that
I've found helpful is the creation of a custom lexer for each parser
state by making the action table entry for that state available to the
lexer. This provides the terminals the parser is looking for, and
narrows the tokens the lexer has to look for at each step.  However,
this means I am also maintaining my own fork of cl-yacc. 

It seems (from my admittedly limited search) that this is not a common
modification of yacc.  Before I start bugging the maintainer about my
changes, I want to know: am I abusing yacc? 

I do like the separation between low level tokenization the higher level
symbol parse, but is there another general parsing technique, available
as a lisp library of course, that either works at a lower level than
yacc usually does or allows the lexer to access more context about the
parse? 

Matt