parsing and semantic analysis using CUP - Access parser stack

Question

I have a rule in my grammar such as

A -> B C D E    {: ...some actions... :}

;

D -> /*empty*/    {: some actions using attributes of B and C :}

;

To implement the actions associated with production rule of D, I need to access the parser stack. How can I do that in CUP?

Answer 1

Rewrite your grammar:

A  -> A1 E
A1 -> B C D 

If the action for the first production requires B and C as well, then the semantic value of A1 will have to be more complicated in order to pass the semantic values through.