Re: Why isn't YYSTYPE created?

[Akim Demaille]

Hi!

Le 20 nov. 2013 à 16:45, Arthur Schwarz <address@hidden> a écrit :

> Win7
> cygwin cygcheck (cygwin) 1.7.25
> 
> bison (GNU Bison) 2.7.1
> 
> The typedef for YYSTYPE is not created in the parser output file (in my case) 
> Slip.bison.cpp nor in any file imported by flex. Is there any reason, e.g., 
> am I doing something wrong or not using a bison option correctly?
> 
> The indication seems to be that if I use %union then YYSTYPE is not defined. 
> Is my reading accurate?

In the case of C++, yes.  It's a completely different interface
compared to the yacc-like API, there is not much point in
reproducing parts of it.

Support for "incoming" YYSTYPE, however, is a different matter,
as it provides the user with a means to define exotic semantic
value types.  However since Bison 3.0 the %define variable
api.value.type makes user-defined YYSTYPE quite obsolete.

> The input from the grammar definition file (Slip.y) is:
> 
> 
>  %file-prefix "Slip.bison"
>  %language "C++"
>  %name-prefix "Slip"
>  %output "Slip.Bison.cpp"
>  
>  %union {
>    int   everything;
>  }
> 
> 
> The generated parser fragment (without #lines) is:
> 
> 
> namespace Slip {
> 
>   /// A Bison parser.
>   class parser
>   {
>   public:
>     /// Symbol semantic values.
> #ifndef YYSTYPE
>     union semantic_type
>     {
> 
>    int   everything;
>     };
> #else
>     typedef YYSTYPE semantic_type;
> #endif