CEDET

I've started building my first wisent parser for graphviz-dot
language.  This goes along a little bit with the new code in
semantic-cb that creates .dot files.

Anyway, I got stuck with EXPANDFULL/EXPAND for a little bit till I
read that I needed to have a %start declaration for each nonterminal
used in %start.  The below patch throws an error so I won't forget
this in the future.

I had some trouble building a wisent happy lexer too.  I think there
is some more error checking to do there too which I will investigate.

Have fun
Eric

*** wisent-grammar.el.~1.8.~	Thu Mar 20 07:38:24 2003
--- wisent-grammar.el	Sun Mar 23 12:38:53 2003
***************
*** 47,53 ****
    "Return expansion of built-in EXPAND expression.
  $I is the placeholder value to expand.
  NONTERM is the nonterminal symbol to start with."
!   (let (($ri (wisent-grammar-region-placeholder $i)))
      (if $ri
          `(semantic-bovinate-from-nonterminal
            (car ,$ri) (cdr ,$ri) ',nonterm)
--- 47,57 ----
    "Return expansion of built-in EXPAND expression.
  $I is the placeholder value to expand.
  NONTERM is the nonterminal symbol to start with."
!   (let ((start (semantic-grammar-start))
! 	($ri (wisent-grammar-region-placeholder $i)))
!     (if (not (member nonterm start))
! 	(error "EXPANDFULL macro called with %s, but not used with %%start."
! 	       nonterm))
      (if $ri
          `(semantic-bovinate-from-nonterminal
            (car ,$ri) (cdr ,$ri) ',nonterm)
***************
*** 57,63 ****
    "Return expansion of built-in EXPANDFULL expression.
  $I is the placeholder value to expand.
  NONTERM is the nonterminal symbol to start with."
!   (let (($ri (wisent-grammar-region-placeholder $i)))
      (if $ri
          `(semantic-parse-region
            (car ,$ri) (cdr ,$ri) ',nonterm 1)
--- 61,71 ----
    "Return expansion of built-in EXPANDFULL expression.
  $I is the placeholder value to expand.
  NONTERM is the nonterminal symbol to start with."
!   (let ((start (semantic-grammar-start))
! 	($ri (wisent-grammar-region-placeholder $i)))
!     (if (not (member nonterm start))
! 	(error "EXPANDFULL macro called with %s, but not used with %%start."
! 	       nonterm))
      (if $ri
          `(semantic-parse-region
            (car ,$ri) (cdr ,$ri) ',nonterm 1)

-- 
          Eric Ludlam:                 zappo@..., eric@...
   Home: http://www.ludlam.net            Siege: http://www.siege-engine.com
Emacs: http://cedet.sourceforge.net               GNU: http://www.gnu.org

Re: [CEDET-devel] wisent compiler patch From: David Ponce <david.ponce@wa...> - 2003-03-23 18:00 Hi Eric, [...] > Anyway, I got stuck with EXPANDFULL/EXPAND for a little bit till I > read that I needed to have a %start declaration for each nonterminal > used in %start. The below patch throws an error so I won't forget > this in the future. That makes sense. Could you check it in, please? > I had some trouble building a wisent happy lexer too. I think there > is some more error checking to do there too which I will > investigate. I am confused here, because there is no true wisent lexer. semantic-lex lexers produce the terminal symbols used in the LALR grammar. Could you elaborate? David

Re[2]: [CEDET-devel] wisent compiler patch From: Eric M. Ludlam <eric@si...> - 2003-03-24 01:22 >>> David Ponce <david.ponce@...> seems to think that: >Hi Eric, > >[...] > > Anyway, I got stuck with EXPANDFULL/EXPAND for a little bit till I > > read that I needed to have a %start declaration for each nonterminal > > used in %start. The below patch throws an error so I won't forget > > this in the future. > >That makes sense. Could you check it in, please? Done. > > I had some trouble building a wisent happy lexer too. I think there > > is some more error checking to do there too which I will > > investigate. > >I am confused here, because there is no true wisent lexer. >semantic-lex lexers produce the terminal symbols used in the LALR >grammar. Could you elaborate? [ ... ] Naturally, I didn't feel like reading up on things first. ;) What I found was that the tokens produced by the lexer have to be mentioned in the grammar file or they can't be used. Here are some things I bumped into. I do not know if good error/warning messages can be generated for them or not. 1) `%token FOO', is not the same as `%token FOO "foo"' - I started with AWK because it was small, and was tricked by that one. 2) `%token <symbol> IDENTIFIER' requires a change in the lexer to actually produce IDENTIFIER tokens. To just use the lexer symbol token, I needed to add `%token <symbol> symbol' which seemed strange. It seems as if you need to write a majority of your own lexer or you can't do anything. It would be nice if there were some defaults I could use so I could make a lexer very close to some default without having to create lots of special things for identifiers, strings, various semantic-list types, etc. I guess I wasn't expecting full duplicity between what the lexer produces, and what you need to tell wisent about so it can create a parser. A side effect of having worked on the bovine parser for so long. 3) graphviz-dot-mode's syntax table things -, >, and other items were of syntax type symbol, not punctuation. Many of my %token entries where then ignored. I've since patched graphviz-dot-mode to use better syntax entries. Have fun Eric -- Eric Ludlam: zappo@..., eric@... Home: http://www.ludlam.net Siege: http://www.siege-engine.com Emacs: http://cedet.sourceforge.net GNU: http://www.gnu.org

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