%{
  /* yacc program for CS4905, Lab 2, balanced  */
  /* parentheses and square brackets.          */
  /* First cut.                                */
#include <ctype.h>
#include <stdio.h>
#define YYSTYPE double /* double type for yacc stack */
%}

%%
lines   :  lines S '\n' { printf("OK \n"); }
        |  lines '\n' 
        |  /* empty */
        |  error '\n' {yyerror("Error: reenter last line:");
                       yyerrok; }
        ;
S       :  S '(' S ')' S
        |  S '[' S ']' S
        |
        ;
%%
#include "lex.yy.c"

void yyerror(char * s)
/* yacc error handler */
{
  fprintf (stderr, "%s\n", s);
}

int main(void) {return yyparse();}