Pushing and poping the semantic stack

[Ilyes Gouta]

Hi guys,

Is there a way to push, pop and peek into bison's semantic stack (i.e,
manipulating the YYSTYPE variables, pushing custom ones) during the
recognition of a rule? My goal is to build an AST during the rule
matching phase and I need these tools for some special cases. I
already  did this (AST construction) but using a separate custom
stack, I'm maintaining during the processing.. but now I would like to
do that using the native bison stack..

Also, is it possible to define YYSTYPE to be a pointer on a structure
instead of a union or a structure? I already tried that and just
checked if it compiles fine and it was OK, however I didn't check the
coherency of the whole recognition process.

Best regards,
Ilyes Gouta.