Print expected tokens in yyerror function.

[Necrosoft]

Hi

I would know the expected token in a parser (GLR also..l) when yyerror
function is invoked. For example:

A = aB | bB
B = b | c
etc....

if the string in input is "ad$", in yyerror I would capture correct tokens
expected...like b or c.

Ho I can make that?

Many Thanks

Bye