daily_programmer_2016_03_28.py

# Finite State Machine
# An Example of Finite State Machine Using Classes
# Responsed to: https://www.reddit.com/r/dailyprogrammer/comments/4cb7eh
class FiniteStateMachine:

    def __init__(self):
        self.states = set([])
        self.transitions = {}
        self.current_state = None

    def set_state(self, state):
        self.states.add(state)

    def set_states(self, states):
        #set a list of states
        assert type(states) == type([]), 'states is not a list'
        self.states = self.states.union(states)

    def set_current_state(self, state):
        assert  state  in self.states, 'state not found in set of current states'
        self.current_state = state

    def set_transition_function(self, trans_name, trans_dict):
        # function that takes as input the current state and returns the state after the transition
        # since the mapping is 1 to 1, we use a simple dictionary to represent
        self.transitions[trans_name] = trans_dict

    def update_trans_function(self, trans_name, prior_state, post_state):
        self.transitions[trans_name][prior_state] = post_state

    def get_current_state(self):
        return self.current_state

    def apply_transition(self, trans_name):
        next_state = self.transitions[trans_name].get(self.current_state)
        # if a state isnt known to the transition function then it stays at it's current state(loops)
        if next_state is None:
            print 'Transition Ignored: State: %s is not defined for Transition Function: %s'%(self.current_state, trans_name)
            next_state = self.current_state
        assert  next_state in self.states, 'transition funciton returned a state that isnt known'
        self.current_state = next_state




if __name__ == "__main__":

    GarageStates = ['OPEN', 'CLOSED', 'STOPPED_WHILE_CLOSING', 'STOPPED_WHILE_OPENING', 'OPENING', 'CLOSING']
    trans_button_clicked = dict([('OPEN', 'CLOSING'), ('OPENING', 'STOPPED_WHILE_OPENING'), ('STOPPED_WHILE_OPENING', 'CLOSING'),
                                 ('CLOSING', 'STOPPED_WHILE_CLOSING'), ('STOPPED_WHILE_CLOSING', 'OPENING'), ('CLOSED', 'OPENING')
                                 ])

    trans_cycle_complete = dict([('OPENING', 'OPEN'), ('CLOSING', 'CLOSED')])

    GarageFSM = FiniteStateMachine()
    GarageFSM.set_states(GarageStates)
    GarageFSM.set_transition_function('button_clicked', trans_button_clicked)
    GarageFSM.set_transition_function('cycle_complete', trans_cycle_complete)
    GarageFSM.set_current_state('CLOSED')

    for trans in ['button_clicked', 'cycle_complete', 'button_clicked', 'button_clicked', 'button_clicked', 'button_clicked', 'button_clicked', 'cycle_complete']:
        print 'Door: '+GarageFSM.get_current_state()
        print '> '+trans
        GarageFSM.apply_transition(trans)

    print 'Door: ' + GarageFSM.get_current_state()
    print '###############################################'
    #Bonus Challenge
    trans_button_clicked = dict(
        [('OPEN', 'CLOSING'), ('OPENING', 'STOPPED_WHILE_OPENING'), ('STOPPED_WHILE_OPENING', 'CLOSING'),
         ('CLOSING', 'STOPPED_WHILE_CLOSING'), ('STOPPED_WHILE_CLOSING', 'OPENING'), ('CLOSED', 'OPENING'),
         ])

    trans_cycle_complete = dict([('OPENING', 'OPEN'), ('CLOSING', 'CLOSED'), ('EMERGENCY_OPENING', 'BLOCKED_OPEN')])
    trans_block_detected = dict([('CLOSING', 'EMERGENCY_OPENING'),
                                 ('STOPPED_WHILE_OPENING', 'BLOCKED_STOPPED_WHILE_OPENING'),
                                 ('STOPPED_WHILE_CLOSING', 'BLOCKED_STOPPED_WHILE_CLOSING'),
                                 ('OPEN', 'BLOCKED_OPEN')
                                 ])
    trans_block_cleared = dict([('BLOCKED_OPEN', 'OPEN'),
                                ('BLOCKED_STOPPED_WHILE_OPENING', 'STOPPED_WHILE_OPENING'),
                                ('BLOCKED_STOPPED_WHILE_CLOSING', 'STOPPED_WHILE_CLOSING')
                                ])

    GarageFSM.set_states(['BLOCKED_STOPPED_WHILE_CLOSING', 'BLOCKED_STOPPED_WHILE_OPENING',  'BLOCKED_OPEN', 'EMERGENCY_OPENING'])
    GarageFSM.set_transition_function('button_clicked', trans_button_clicked)
    GarageFSM.set_transition_function('cycle_complete', trans_cycle_complete)
    GarageFSM.set_transition_function('block_detected', trans_block_detected)
    GarageFSM.set_transition_function('block_cleared', trans_block_cleared)
    GarageFSM.set_current_state('CLOSED')

    for trans in ['button_clicked',  'cycle_complete', 'button_clicked', 'block_detected', 'button_clicked',
                  'cycle_complete', 'button_clicked', 'block_cleared', 'button_clicked','cycle_complete']:
        print 'Door: ' + GarageFSM.get_current_state()
        print '> ' + trans
        GarageFSM.apply_transition(trans)

    print 'Door: ' + GarageFSM.get_current_state()