How to retrieve all values from yacc/bison grammar keeps in value stack when error occurs?

Hi,
  I have written a simple bison grammar which gets inut from local file and send the ouput as it is with out modifying anything to another file. If any input from file has different format from bison grammar, then bison grammar failes to match input tokens and calls yyerror() function. This case I lost the inputs and bison will not take further inputs from file also(execution stoped). I want handle something, when  error occur on grammar, bison should flush all values to output so that same input copied to ouput and then start taking next input from ex for further grammar check.

Thanks in advance.