baseimage-tutorial-framework/lib/tfw/fsm/linear_fsm.py

from transitions import State

from tfw.fsm.fsm_base import FSMBase


class LinearFSM(FSMBase):
    # pylint: disable=anomalous-backslash-in-string
    """
    This is a state machine for challenges with linear progression, consisting of
    a number of steps specified in the constructor. It automatically sets up 2
    actions (triggers) between states as such:
    (0) --  step_1     --> (1) --  step_2     --> (2) --  step_3     --> (3) ...
    (0) --  step_next  --> (1) --  step_next  --> (2) --  step_next  --> (3) ...
    """
    def __init__(self, number_of_steps):
        """
        :param number_of_steps: how many states this FSM should have
        """
        self.states = [State(name=str(index)) for index in range(number_of_steps)]
        self.transitions = []
        for state in self.states[:-1]:
            self.transitions.append({
                'trigger': f'step_{int(state.name)+1}',
                'source': state.name,
                'dest': str(int(state.name)+1)
            })
            self.transitions.append({
                'trigger': 'step_next',
                'source': state.name,
                'dest': str(int(state.name)+1)
            })
        super(LinearFSM, self).__init__()