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Date: -- (:)
From: Pietro Abate <Pietro.Abate@a...>
Subject: camlp4 help
Hi all,
I'm having problems (once again) with camlp4...

I'd like to parse and produce a bit of ocaml code out of the
following description :

---------------------
CONNECTIVES
    "_&_",AssocLeft,And ;
    "_v_",AssocLeft,Or
END

TABLEAU

    RULE "And"
    { A & B }
    ----------
      A ; B
    END

END
---------------

The first time around I used quotes around the "{A & B}" and parsed the
expression with a adhoc parser outside camlp4 (and it's all good and
working).  Now I want to remove the quotes tut-cur and do everything
using the pre-processor (quotes make my code quote un-readable).  I've
started writing this code below, but I don't know how to proceed...

The main problem is of course that I've to parse an expression (in rule),
with a generic parser built on the top of the connectives that I've just
declared. Is there a way to tell campl4 : pass everything in between 
RULE and END to a function my_parser ?

I was looking for inspiration in M. Jambon excellent tutorial, but 
without much luck... 

thanks,
p

-----------------------(not tested)
let rule = Grammar.Entry.create Pcaml.gram "rule";;
let connective = Grammar.Entry.create Pcaml.gram "connective";;

type assoc = |AssocLeft |AssocRight |AssocNone ;;

let conntable = Hashtbl.create 15;;

EXTEND
  Pcaml.str_item: [
    "CONNECTIVES"; clist = LIST1 connective SEP ";"; "END" ->
      List.iter Hashtbl.add conntable clist;
      <:str_item< value version = "connectives declared" >>
    |"TABLEAU"; LIST1 rule; "END" ->
        <:str_item< value version = "tableau declared" >>
  ];

  connective: [
    s = STRING; ","; a = UIDENT; ","; r = UIDENT -> (s,a,r)
  ];

  (* how can I write a quotation outside the EXTEND syntax ? *)
  (* how does this quotation looks like ? *)
  (* Quotation.add my_parser ??? *)
  rule: [
    "RULE"; r = my_parser ??? "END" -> do_something r
  ];
  
END
------------------------

-- 
++ Blog: http://blog.rsise.anu.edu.au/?q=pietro
++ 
++ "All great truths begin as blasphemies." -George Bernard Shaw
++ Please avoid sending me Word or PowerPoint attachments.
   See http://www.fsf.org/philosophy/no-word-attachments.html