Has anyone considered adding extended BNF to Bison? I refer to things like
A. p : a? ; B. p : a ( b | c ) d ; C. p : a ( ',' a )* D. p : a+ and so forth. There are numerous questions to answer, mostly involving semantic actions and including: 1. How do we specify the semantic types of such constructs? 2. How do we refer to, e.g., the values of b and c from example B in actions? Presumably this would only be legal inside the parentheses. 3. Assuming we translate * and + into equivalent non-extended productions, how do we specify left vs. right-recursive lists? 4. How do we specify list constructors for * and +? 5. How do we supply a value for the empty case in A? 6. How do we supply a value for the ( ... ) construct in B? Paul Hilfinger _______________________________________________ help-bison@gnu.org http://lists.gnu.org/mailman/listinfo/help-bison
