Limitations on $n in ocamlyacc?

Limitations on $n in ocamlyacc?

[Alex Baretta]

What is the limit on the number of token values accessible with the $n
notation in ocamlyacc semantic actions? I'm asking because I'm
consistently getting ocamlyacc errors like the following, which I can't
make sense of.

ocamlyacc: e - line 96 of "xcaml_dictionary_yacc.mly", $5 is unbound


Alex

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Re: [Caml-list] Limitations on $n in ocamlyacc?

[Alex Baretta]

Alex Baretta wrote:
> What is the limit on the number of token values accessible with the $n
> notation in ocamlyacc semantic actions? I'm asking because I'm
> consistently getting ocamlyacc errors like the following, which I can't
> make sense of.
> 
> ocamlyacc: e - line 96 of "xcaml_dictionary_yacc.mly", $5 is unbound

The obvious answer is...
... PEBKAC!

The was one unterminated semantic actions tens of lines above the spot
where the ocamlyacc was unable to proceed. Casually, the syntax
production contained 4 symbols; hence, the unbound $5...

Alex



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tel. +39 02 370 111 55
fax. +39 02 370 111 54

Our technology:

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Re: [Caml-list] Limitations on $n in ocamlyacc?

[John Skaller]

On Fri, 2005-05-27 at 10:24 +0200, Alex Baretta wrote:
> What is the limit on the number of token values accessible with the $n
> notation in ocamlyacc semantic actions? I'm asking because I'm
> consistently getting ocamlyacc errors like the following, which I can't
> make sense of.
> 
> ocamlyacc: e - line 96 of "xcaml_dictionary_yacc.mly", $5 is unbound

This is because the symbol has no argument:

%token FRED
p: FRED { $1 } 

will give this error, but

%token<int> JOE

q: JOE { $1 } 

makes non-terminal q of type int, the type of JOE's argument.

It is equivalent to:

type token = 
 | FRED
 | JOE of int

then

match (x:token) with 
| FRED ?a -> .. (* ERROR -- FRED is a constant constructor *)
| JOE ?a -> .. (* OK -- JOE is a nonconstant constructor *)

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