Re: $$

[Nigel Stewart & Fiona Smith]

Mike,

$$ is the return value for the current rule,
the type of which must be specified with
a %type statement in the bison preamble.

For example:

%union {
bool     bval;
int      ival;
float    fval;
char     *sval;
}

...

%type <bval> SFBool

%{

SFBool
        : TRUEFALSE { $$ = $1; };

Where $1 denotes whatever flex matched for TRUEFALSE.
Actually, the flex rule looks like this:

TRUE    { yylval.bval = true;  return TRUEFALSE; }



Mike Rollins wrote:
> What "type" exactly, is '$$'?  Whenever I attempt to use it, I get:
>
> $$ of `QualifiedName' has no declared type
>
> My union is as follows:
>
> %union{
>         char* ID
> }
>
> and later I have:
>
> %token <ID> IDENTIFIER
>
> However, even if I do the following:
>
> ...{$$.ID = yylval.ID;}...
>
> I still get the above error.  What am I doing wrong?
>
> Thanks,
>
> Mike