sticking custom meta informations to grammar rules

[Christian Schoenebeck]

Hi everybody!

I am currently working on a shell and wrote custom C++ code that takes Bison's 
symbol stack at a certain point (i.e. when an error occured) and walks ahead 
the Bison generated yyfoo tables / tree of the shell's grammar. I added that 
custom code for two purposes: 1) providing very user friendly error messages 
on syntax errors and 2) providing the user visual auto completion & auto 
correction while typing in the shell.

It is already working, however to make those syntax error messages and auto 
completion suggestions even more appropriate & human friendly, I would need to 
stick some additional custom meta informations to the individual grammar 
rules. It could be as simple as binding my own constant number to each grammar 
rule like (pseudo code):

        enum {
                MY_META_INFO1 = 3,
                MY_META_INFO2 = 7,
                ...
        };

        ...

        foo             :  bla    custom_meta(MY_META_INFO8)
                        |  bar    custom_meta(MY_META_INFO2)
                        |  command number    custom_meta(MY_META_INFO3) 
                        ;

So that I am able to lookup those constants by the respective Bison grammar 
rule index number at runtime and accordingly to associate grammar rules in the 
Bison generated yyfoo tables with my own table(s), where the latter would 
provide my own, more detailed informations about individual grammar rules.

I hope this somehow explains what I am trying to get at. ;-)

Is there already some kind of solution for that in Bison? Or does anybody know 
a work around to achieve something like that?

Best regards,
Christian Schoenebeck