baseimage-tutorial-framework/lib/tfw/fsm_base.py

# Copyright (C) 2018 Avatao.com Innovative Learning Kft.
# All Rights Reserved. See LICENSE file for details.

from typing import List

from transitions import Machine

from tfw.mixins import CallbackMixin


class FSMBase(CallbackMixin):
    """
    A general FSM base class you can inherit from to track user progress.
    See linear_fsm.py for an example use-case.
    TFW uses the transitions library for state machines, please refer to their
    documentation for more information on creating your own machines:
    https://github.com/pytransitions/transitions
    """
    states, transitions = [], []

    def __init__(self, initial: str = None, accepted_states: List[str] = None):
        self.accepted_states = accepted_states or [self.states[-1]]
        self.machine = Machine(
            model=self,
            states=self.states,
            transitions=self.transitions,
            initial=initial or self.states[0],
            send_event=True,
            ignore_invalid_triggers=True,
            after_state_change='execute_callbacks'
        )

    def execute_callbacks(self, event_data):
        self._execute_callbacks(event_data.kwargs)

    def is_solved(self):
        return self.state in self.accepted_states # pylint: disable=no-member