Universal Machine Python Matti565

class TuringMachine(object):
    def __init__(self, alphabet, states, initial_state, accept_state, initial_tape):

        '''
        alphabet is a string of non-whitespace characters. They determine the possible values of the tape
        states is a string of whitespace-separated characters. They are the states that the machine can use
        initial_state is a string that is one element of states. It determines the starting state of the machine
        accept_state is a string that is one element of states. If accept_state gets called, the machine halts
        initial_tape is the starting tape of the machine
        '''

        self.alphabet = [e for e in alphabet]
        self.states = states.split()
        self.curr_state = initial_state
        if self.curr_state not in states:
            raise ValueError('initial_state not in states')
        self.accept_state = accept_state
        if self.accept_state not in states:
            raise ValueError('accept_state not in states')
        self.tape = [e for e in initial_tape]
        for e in self.tape:
            if e not in self.alphabet:
                raise ValueError('tape contains arguments that are not in alphabet')
        self.rules = {}
        self.position = 0

    def add_rule(self, rule):
        '''
        rule is string in the format StateBefore SymbolBefore = StateAfter SymbolAfter DirectionToMove
        '''
        rule = rule.split()
        self.rules[(rule[0], rule[1])] = (rule[3],rule[4],rule[5])

    def add_rulebook(self, rulebook):
        for e in rulebook.splitlines():
            self.add_rule(e)

    def next(self):
        "executes one cycle"
        if self.position >= self.tape.__len__():
            self.tape.append('_')
        rule = self.rules[(self.curr_state, self.tape[self.position])]
        self.curr_state = rule[0]
        self.tape[self.position] = rule[1]
        if rule[2] == '>':
            self.position += 1
        elif rule[2] == '<':
            self.position -= 1

    def print(self):
        for e in self.tape:
            print(e,end = '')
        print()
        print('|',end = '')
        for e in range(1, self.tape.__len__()):
            if e == self.position:
                print('^', end = '')
            else:
                print(' ', end = '')
        print('',end = '\n')

    def execute(self):
        while self.curr_state != self.accept_state:
            self.next()
        self.print()

alphabet = input('alphabet: ')
states = input('states: ')
initial_state = input('initial_state: ')
accept_state = input('accept_state: ')
initial_tape = input('initial_tape: ')
t = TuringMachine(alphabet, states, initial_state, accept_state, initial_tape)
for line in iter(input('rulebook', '')):
    t.add_rule(line)
t.execute()