text: xx(TK_INT)
  xx(TK_CHAR)
  xx(TK_CONST)
  xx(TK_VOID)
  xx(TK_RETURN)
  xx(TK_OP_SIZEOF)
  xx(TK_IF)
  xx(TK_ELSE)
  xx(TK_SWITCH)
  xx(TK_CASE)
  xx(TK_DEFAULT)
  xx(TK_WHILE)
  xx(TK_DO)
  xx(TK_FOR)
  xx(TK_BREAK)
  xx(TK_CONTINUE)
  xx(TK_GOTO)
  xx(TK_IDENTIFIER)
  xx(TK_CONST_INT)    
  xx(TK_CONST_STRING)