Re: [CEDET-devel] Lexical analyzer problem - now parser problem

[David E. <de...@ra...>]

Alastair Rankine writes:
> I'm trying to parse this:
>
>     project(LLVM)
>
> Here is the relevant extract from my bovine grammar:
>
>
> command : symbol semantic-list
>           (FUNCTION-TAG ,$1 nil (EXPAND $2 params))
>         ;
>
> params : LPAREN arg RPAREN ( VARIABLE-TAG ,$2 nil nil )
>        | LPAREN RPAREN ;; empty
>        ;
>
> arg : symbol
>     | string
>     | number
>     ;
>
>
> The intent here is to create a function tag with name "project" and an argument list with a single variable tag "LLVM". Unfortunately I can't seem to get it to work - see backtrace:
>
>
> Debugger entered: ((("project" function (:arguments (("LLVM") variable nil nil nil 84 90)) nil nil) 77 90))
>   byte-code("\301\302!\210\303!\207" [tag message "A Rule must return a single tag-line list!" debug] 2)
>   semantic--tag-expand((("project" function (:arguments ...) nil nil) 77 90))
>   semantic-repeat-parse-whole-stream(((symbol 77 . 84) (semantic-list 84 . 90)) nil nil)
>   semantic-parse-region-default(1 130 nil nil nil)
>   semantic-parse-region(1 130)
>   semantic-fetch-tags()
>   bovinate(nil)
>
>
> I don't understand this error message. I think this is saying that the
> argument list returned by parsing "params" has to be a list of tags,
> but from what I can see, it is.
>
> I'm obviously doing something fundamentally wrong here - can you or
> anyone else help?

It's a bit hard to tell, but what strikes me is that

(("LLVM") variable nil nil nil 84 90))

has the name 'LLVM' in a list, whereas it should be a plain string. So I
guess in 'params' you'll need a 'car':

( VARIABLE-TAG (car $2) nil nil )

Also, I hope you know that Bovine has a stepping debugger which you can
use by simply calling 'semantic-debug'. If you're unsure what exactly
you're getting from all those rules, you can simply define a dummy
function in *scratch* like

(defun showargs (&optional one two three four)
       (message "debug!"))

and then call that one in the grammar, like

 command : symbol semantic-list
           ( ,(showargs ,$1 (EXPAND $2 params)) )

You can then use debug-on-entry/edebug on 'showargs' and better see what
kind of arguments you're actually dealing with. Maybe there's also a
magic key somewhere in the bovine debugger to show that, but I don't
think so.

Cheers,
David