Method execute

PyBasic/program.py:323–474

Execute the program

(self,infile,tmpfile)

    def execute(self,infile,tmpfile):
        """Execute the program"""

        self.__parser = BASICParser()

        self.__data.restore(0) # reset data pointer

        line_numbers = self.line_numbers()

        if len(line_numbers) > 0:
            # Set up an index into the ordered list
            # of line numbers that can be used for
            # sequential statement execution. The index
            # will be incremented by one, unless modified by
            # a jump
            index = 0
            self.__next_stmt = line_numbers[index]

            # Run through the program until the
            # has line number has been reached
            while True:
                flowsignal = self.__execute(self.__next_stmt,infile,tmpfile)
                self.__parser.last_flowsignal = flowsignal


                if flowsignal:
                    if flowsignal.ftype == FlowSignal.SIMPLE_JUMP:
                        # GOTO or conditional branch encountered
                        try:
                            index = line_numbers.index(flowsignal.ftarget)

                        except ValueError:
                            raise RuntimeError("Invalid line number supplied in GOTO or conditional branch: "
                                               + str(flowsignal.ftarget)+ " in line " + str(self.__next_stmt))

                        self.__next_stmt = flowsignal.ftarget

                    elif flowsignal.ftype == FlowSignal.GOSUB:
                        # Subroutine call encountered
                        # Add line number of next instruction to
                        # the return stack
                        if index + 1 < len(line_numbers):
                            self.__return_stack.append(line_numbers[index + 1])

                        else:
                            raise RuntimeError("GOSUB at end of program, nowhere to return")

                        # Set the index to be the subroutine start line
                        # number
                        try:
                            index = line_numbers.index(flowsignal.ftarget)

                        except ValueError:
                            raise RuntimeError("Invalid line number supplied in subroutine call: "
                                               + str(flowsignal.ftarget))

                        self.__next_stmt = flowsignal.ftarget