# -*- coding: utf-8 -*- from collections import OrderedDict, defaultdict import copy from functools import partial, reduce import inspect import logging from six import string_types from ..core import State, Machine, Transition, Event, listify, MachineError, Enum, EnumMeta, EventData _LOGGER = logging.getLogger(__name__) _LOGGER.addHandler(logging.NullHandler()) # this is a workaround for dill issues when partials and super is used in conjunction # without it, Python 3.0 - 3.3 will not support pickling # https://github.com/pytransitions/transitions/issues/236 _super = super # converts a hierarchical tree into a list of current states def _build_state_list(state_tree, separator, prefix=[]): res = [] for key, value in state_tree.items(): if value: res.append(_build_state_list(value, separator, prefix=prefix + [key])) else: res.append(separator.join(prefix + [key])) return res if len(res) > 1 else res[0] # custom breadth-first tree exploration # makes sure that ALL children are evaluated before parents in parallel states def _resolve_order(state_tree): s = state_tree q = [] res = [] p = [] while True: for k in reversed(list(s.keys())): pk = p + [k] res.append(pk) if s[k]: q.append((pk, s[k])) if not q: break p, s = q.pop(0) return reversed(res) class FunctionWrapper(object): """ A wrapper to enable transitions' convenience function to_ for nested states. This allows to call model.to_A.s1.C() in case a custom separator has been chosen.""" def __init__(self, func, path): """ Args: func: Function to be called at the end of the path. path: If path is an empty string, assign function """ if path: self.add(func, path) self._func = None else: self._func = func def add(self, func, path): """ Assigns a `FunctionWrapper` as an attribute named like the next segment of the substates path. Args: func (callable): Function to be called at the end of the path. path (string): Remaining segment of the substate path. """ if path: name = path[0] if name[0].isdigit(): name = 's' + name if hasattr(self, name): getattr(self, name).add(func, path[1:]) else: setattr(self, name, FunctionWrapper(func, path[1:])) else: self._func = func def __call__(self, *args, **kwargs): return self._func(*args, **kwargs) class NestedEvent(Event): """ An event type to work with nested states. This subclass is NOT compatible with simple Machine instances. """ def trigger(self, _model, _machine, *args, **kwargs): """ Executes all transitions that match the current state, halting as soon as one successfully completes. More precisely, it prepares a partial of the internal ``_trigger`` function, passes this to ``machine._process``. It is up to the machine's configuration of the Event whether processing happens queued (sequentially) or whether further Events are processed as they occur. NOTE: This should only be called by HierarchicalMachine instances. Args: _model (object): The currently processed model _machine (HierarchicalMachine): Since NestedEvents can be used in multiple machine instances, this one will be used to determine the current state separator and the current scope. args and kwargs: Optional positional or named arguments that will be passed onto the EventData object, enabling arbitrary state information to be passed on to downstream triggered functions. Returns: boolean indicating whether or not a transition was successfully executed (True if successful, False if not). """ # Save the current scope (_machine.scoped, _machine.states, _machine.events) in partial # since queued transitions could otherwise loose their scope. func = partial(self._trigger, _model, _machine, (_machine.scoped, _machine.states, _machine.events, _machine.prefix_path), *args, **kwargs) # pylint: disable=protected-access # noinspection PyProtectedMember # Machine._process should not be called somewhere else. That's why it should not be exposed # to Machine users. return _machine._process(func) def _trigger(self, _model, _machine, _scope, *args, **kwargs): """ Internal trigger function called by the ``HierarchicalMachine`` instance. This should not be called directly but via the public method ``HierarchicalMachine.process``. In contrast to the inherited ``Event._trigger``, this requires a scope tuple to process triggers in the right context. Args: _model (object): The currently processed model _machine (HierarchicalMachine): The machine that should be used to process the event _scope (Tuple): A tuple containing information about the currently scoped object, states an transitions. args and kwargs: Optional positional or named arguments that will be passed onto the EventData object, enabling arbitrary state information to be passed on to downstream triggered functions. Returns: boolean indicating whether or not a transition was successfully executed (True if successful, False if not). """ if _scope[0] != _machine.scoped: with _machine(_scope): return self._trigger_scoped(_model, _machine, *args, **kwargs) else: return self._trigger_scoped(_model, _machine, *args, **kwargs) def _trigger_scoped(self, _model, _machine, *args, **kwargs): """ Internal scope-adjusted trigger function called by the ``NestedEvent._trigger`` instance. This should not be called directly. Args: _model (object): The currently processed model _machine (HierarchicalMachine): The machine that should be used to process the event args and kwargs: Optional positional or named arguments that will be passed onto the EventData object, enabling arbitrary state information to be passed on to downstream triggered functions. Returns: boolean indicating whether or not a transition was successfully executed (True if successful, False if not). """ state_tree = _machine._build_state_tree(getattr(_model, _machine.model_attribute), _machine.state_cls.separator) state_tree = reduce(dict.get, _machine.get_global_name(join=False), state_tree) ordered_states = _resolve_order(state_tree) done = set() res = None for state_path in ordered_states: state_name = _machine.state_cls.separator.join(state_path) if state_name not in done and state_name in self.transitions: state = _machine.get_state(state_name) event_data = EventData(state, self, _machine, _model, args=args, kwargs=kwargs) event_data.source_name = state_name event_data.source_path = copy.copy(state_path) res = self._process(event_data) if res: elems = state_path while elems: done.add(_machine.state_cls.separator.join(elems)) elems.pop() return res def _process(self, event_data): machine = event_data.machine machine.callbacks(event_data.machine.prepare_event, event_data) _LOGGER.debug("%sExecuted machine preparation callbacks before conditions.", machine.name) try: for trans in self.transitions[event_data.source_name]: event_data.transition = trans if trans.execute(event_data): event_data.result = True break except Exception as err: event_data.error = err if self.machine.on_exception: self.machine.callbacks(self.machine.on_exception, event_data) else: raise finally: try: machine.callbacks(machine.finalize_event, event_data) _LOGGER.debug("%sExecuted machine finalize callbacks", machine.name) except Exception as err: _LOGGER.error("%sWhile executing finalize callbacks a %s occurred: %s.", self.machine.name, type(err).__name__, str(err)) return event_data.result class NestedState(State): """ A state which allows substates. Attributes: states (OrderedDict): A list of substates of the current state. events (dict): A list of events defined for the nested state. initial (list, str, NestedState or Enum): (Name of a) child or list of children that should be entered when the state is entered. exit_stack (defaultdict): A list of currently active substates """ separator = '_' u""" Separator between the names of parent and child states. In case '_' is required for naming state, this value can be set to other values such as '.' or even unicode characters such as '↦' (limited to Python 3 though). """ def __init__(self, name, on_enter=None, on_exit=None, ignore_invalid_triggers=None, initial=None): _super(NestedState, self).__init__(name=name, on_enter=on_enter, on_exit=on_exit, ignore_invalid_triggers=ignore_invalid_triggers) self.initial = initial self.events = {} self.states = OrderedDict() self._scope = [] def add_substate(self, state): """ Adds a state as a substate. Args: state (NestedState): State to add to the current state. """ self.add_substates(state) def add_substates(self, states): """ Adds a list of states to the current state. Args: states (list): List of states to add to the current state. """ for state in listify(states): self.states[state.name] = state def scoped_enter(self, event_data, scope=[]): self._scope = scope try: self.enter(event_data) finally: self._scope = [] def scoped_exit(self, event_data, scope=[]): self._scope = scope try: self.exit(event_data) finally: self._scope = [] @property def name(self): return self.separator.join(self._scope + [_super(NestedState, self).name]) class NestedTransition(Transition): """ A transition which handles entering and leaving nested states. Attributes: source (str): Source state of the transition. dest (str): Destination state of the transition. prepare (list): Callbacks executed before conditions checks. conditions (list): Callbacks evaluated to determine if the transition should be executed. before (list): Callbacks executed before the transition is executed but only if condition checks have been successful. after (list): Callbacks executed after the transition is executed but only if condition checks have been successful. """ def _resolve_transition(self, event_data): machine = event_data.machine dst_name_path = self.dest.split(event_data.machine.state_cls.separator) _ = machine.get_state(dst_name_path) model_states = listify(getattr(event_data.model, machine.model_attribute)) state_tree = machine._build_state_tree(model_states, machine.state_cls.separator) scope = machine.get_global_name(join=False) src_name_path = event_data.source_path if src_name_path == dst_name_path: root = src_name_path[:-1] # exit and enter the same state dst_name_path = dst_name_path[-1:] else: tmp_tree = state_tree.get(dst_name_path[0], None) root = [] while tmp_tree is not None: root.append(dst_name_path.pop(0)) tmp_tree = tmp_tree.get(dst_name_path[0], None) if len(dst_name_path) > 0 else None scoped_tree = reduce(dict.get, scope + root, state_tree) exit_partials = [partial(machine.get_state(root + state_name).scoped_exit, event_data, scope + root + state_name[:-1]) for state_name in _resolve_order(scoped_tree)] if dst_name_path: new_states, enter_partials = self._enter_nested(root, dst_name_path, scope + root, event_data) else: new_states, enter_partials = {}, [] scoped_tree.clear() for new_key, value in new_states.items(): scoped_tree[new_key] = value break return state_tree, exit_partials, enter_partials def _change_state(self, event_data): state_tree, exit_partials, enter_partials = self._resolve_transition(event_data) for func in exit_partials: func() self._update_model(event_data, state_tree) for func in enter_partials: func() def _enter_nested(self, root, dest, prefix_path, event_data): if root: state_name = root.pop(0) with event_data.machine(state_name): return self._enter_nested(root, dest, prefix_path, event_data) elif dest: new_states = OrderedDict() state_name = dest.pop(0) with event_data.machine(state_name): new_states[state_name], new_enter = self._enter_nested([], dest, prefix_path + [state_name], event_data) enter_partials = [partial(event_data.machine.scoped.scoped_enter, event_data, prefix_path)] + new_enter return new_states, enter_partials elif event_data.machine.scoped.initial: new_states = OrderedDict() enter_partials = [] q = [] prefix = prefix_path scoped_tree = new_states initial_names = [i.name if hasattr(i, 'name') else i for i in listify(event_data.machine.scoped.initial)] initial_states = [event_data.machine.scoped.states[n] for n in initial_names] while True: event_data.scope = prefix for state in initial_states: enter_partials.append(partial(state.scoped_enter, event_data, prefix)) scoped_tree[state.name] = OrderedDict() if state.initial: q.append((scoped_tree[state.name], prefix + [state.name], [state.states[i.name] if hasattr(i, 'name') else state.states[i] for i in listify(state.initial)])) if not q: break scoped_tree, prefix, initial_states = q.pop(0) return new_states, enter_partials else: return {}, [] @staticmethod def _update_model(event_data, tree): model_states = _build_state_list(tree, event_data.machine.state_cls.separator) with event_data.machine(): event_data.machine.set_state(model_states, event_data.model) states = event_data.machine.get_states(listify(model_states)) event_data.state = states[0] if len(states) == 1 else states # Prevent deep copying of callback lists since these include either references to callable or # strings. Deep copying a method reference would lead to the creation of an entire new (model) object # (see https://github.com/pytransitions/transitions/issues/248) def __deepcopy__(self, memo): cls = self.__class__ result = cls.__new__(cls) memo[id(self)] = result for key, value in self.__dict__.items(): if key in cls.dynamic_methods: setattr(result, key, copy.copy(value)) else: setattr(result, key, copy.deepcopy(value, memo)) return result class HierarchicalMachine(Machine): """ Extends transitions.core.Machine by capabilities to handle nested states. A hierarchical machine REQUIRES NestedStates, NestedEvent and NestedTransitions (or any subclass of it) to operate. """ state_cls = NestedState transition_cls = NestedTransition event_cls = NestedEvent def __init__(self, *args, **kwargs): assert issubclass(self.state_cls, NestedState) assert issubclass(self.event_cls, NestedEvent) assert issubclass(self.transition_cls, NestedTransition) self._stack = [] self.prefix_path = [] self.scoped = self _super(HierarchicalMachine, self).__init__(*args, **kwargs) def __call__(self, to_scope=None): if isinstance(to_scope, string_types): state_name = to_scope.split(self.state_cls.separator)[0] state = self.states[state_name] to_scope = (state, state.states, state.events, self.prefix_path + [state_name]) elif isinstance(to_scope, Enum): state = self.states[to_scope.name] to_scope = (state, state.states, state.events, self.prefix_path + [to_scope.name]) elif to_scope is None: if self._stack: to_scope = self._stack[0] else: to_scope = (self, self.states, self.events, []) self._next_scope = to_scope return self def __enter__(self): self._stack.append((self.scoped, self.states, self.events, self.prefix_path)) self.scoped, self.states, self.events, self.prefix_path = self._next_scope self._next_scope = None def __exit__(self, exc_type, exc_val, exc_tb): self.scoped, self.states, self.events, self.prefix_path = self._stack.pop() def add_model(self, model, initial=None): """ Extends transitions.core.Machine.add_model by applying a custom 'to' function to the added model. """ models = [self if mod is self.self_literal else mod for mod in listify(model)] _super(HierarchicalMachine, self).add_model(models, initial=initial) initial_name = getattr(models[0], self.model_attribute) if hasattr(initial_name, 'name'): initial_name = initial_name.name # initial states set by add_model or machine might contain initial states themselves. if isinstance(initial_name, string_types): initial_states = self._resolve_initial(models, initial_name.split(self.state_cls.separator)) # when initial is set to a (parallel) state, we accept it as it is else: initial_states = initial_name for mod in models: self.set_state(initial_states, mod) if hasattr(mod, 'to'): _LOGGER.warning("%sModel already has a 'to'-method. It will NOT " "be overwritten by NestedMachine", self.name) else: to_func = partial(self.to_state, mod) setattr(mod, 'to', to_func) @property def initial(self): """ Return the initial state. """ return self._initial @initial.setter def initial(self, value): self._initial = self._recursive_initial(value) def add_ordered_transitions(self, states=None, trigger='next_state', loop=True, loop_includes_initial=True, conditions=None, unless=None, before=None, after=None, prepare=None, **kwargs): if states is None: states = self.get_nested_state_names() _super(HierarchicalMachine, self).add_ordered_transitions(states=states, trigger=trigger, loop=loop, loop_includes_initial=loop_includes_initial, conditions=conditions, unless=unless, before=before, after=after, prepare=prepare, **kwargs) def add_states(self, states, on_enter=None, on_exit=None, ignore_invalid_triggers=None, **kwargs): """ Add new nested state(s). Args: states (list, str, dict, Enum, NestedState or Machine): a list, a NestedState instance, the name of a new state, an enumeration (member) or a dict with keywords to pass on to the NestedState initializer. If a list, each element can be a string, dict, NestedState or enumeration member. on_enter (str or list): callbacks to trigger when the state is entered. Only valid if first argument is string. on_exit (str or list): callbacks to trigger when the state is exited. Only valid if first argument is string. ignore_invalid_triggers: when True, any calls to trigger methods that are not valid for the present state (e.g., calling an a_to_b() trigger when the current state is c) will be silently ignored rather than raising an invalid transition exception. Note that this argument takes precedence over the same argument defined at the Machine level, and is in turn overridden by any ignore_invalid_triggers explicitly passed in an individual state's initialization arguments. **kwargs additional keyword arguments used by state mixins. """ remap = kwargs.pop('remap', None) ignore = self.ignore_invalid_triggers if ignore_invalid_triggers is None else ignore_invalid_triggers for state in listify(states): if isinstance(state, Enum): if isinstance(state.value, EnumMeta): state = {'name': state, 'children': state.value} elif isinstance(state.value, dict): state = dict(name=state, **state.value) if isinstance(state, string_types): if remap is not None and state in remap: return domains = state.split(self.state_cls.separator, 1) if len(domains) > 1: try: self.get_state(domains[0]) except ValueError: self.add_state(domains[0], on_enter=on_enter, on_exit=on_exit, ignore_invalid_triggers=ignore_invalid_triggers, **kwargs) with self(domains[0]): self.add_states(domains[1], on_enter=on_enter, on_exit=on_exit, ignore_invalid_triggers=ignore_invalid_triggers, **kwargs) else: if state in self.states: raise ValueError("State {0} cannot be added since it already exists.".format(state)) new_state = self._create_state(state, on_enter=on_enter, on_exit=on_exit, ignore_invalid_triggers=ignore, **kwargs) self.states[new_state.name] = new_state self._init_state(new_state) elif isinstance(state, Enum): if self.state_cls.separator in state.name: raise ValueError("State '{0}' contains '{1}' which is used as state name separator. " "Consider changing the NestedState.separator to avoid this issue." "".format(state.name, self.state_cls.separator)) if remap is not None and state.name in remap: return new_state = self._create_state(state, on_enter=on_enter, on_exit=on_exit, ignore_invalid_triggers=ignore, **kwargs) if state.name in self.states: raise ValueError("State {0} cannot be added since it already exists.".format(state.name)) self.states[new_state.name] = new_state self._init_state(new_state) elif isinstance(state, dict): if remap is not None and state['name'] in remap: return state = state.copy() # prevent messing with the initially passed dict remap = state.pop('remap', None) if 'ignore_invalid_triggers' not in state: state['ignore_invalid_triggers'] = ignore # parallel: [states] is just a short handle for {children: [states], initial: [state_names]} state_parallel = state.pop('parallel', []) if state_parallel: state_children = state_parallel state['initial'] = [s['name'] if isinstance(s, dict) else s for s in state_children] else: state_children = state.pop('children', state.pop('states', [])) transitions = state.pop('transitions', []) new_state = self._create_state(**state) self.states[new_state.name] = new_state self._init_state(new_state) remapped_transitions = [] with self(new_state.name): self.add_states(state_children, remap=remap, **kwargs) if remap is not None: drop_event = [] for evt in self.events.values(): self.events[evt.name] = copy.copy(evt) for trigger, event in self.events.items(): drop_source = [] event.transitions = copy.deepcopy(event.transitions) for source_name, trans_source in event.transitions.items(): if source_name in remap: drop_source.append(source_name) continue drop_trans = [] for trans in trans_source: if trans.dest in remap: conditions, unless = [], [] for cond in trans.conditions: # split a list in two lists based on the accessors (cond.target) truth value (unless, conditions)[cond.target].append(cond.func) remapped_transitions.append({ 'trigger': trigger, 'source': new_state.name + self.state_cls.separator + trans.source, 'dest': remap[trans.dest], 'conditions': conditions, 'unless': unless, 'prepare': trans.prepare, 'before': trans.before, 'after': trans.after}) drop_trans.append(trans) for t in drop_trans: trans_source.remove(t) if not trans_source: drop_source.append(source_name) for s in drop_source: del event.transitions[s] if not event.transitions: drop_event.append(trigger) for e in drop_event: del self.events[e] if transitions: self.add_transitions(transitions) self.add_transitions(remapped_transitions) elif isinstance(state, NestedState): if state.name in self.states: raise ValueError("State {0} cannot be added since it already exists.".format(state.name)) self.states[state.name] = state self._init_state(state) elif isinstance(state, Machine): new_states = [s for s in state.states.values() if remap is None or s not in remap] self.add_states(new_states) for ev in state.events.values(): self.events[ev.name] = ev if self.scoped.initial is None: self.scoped.initial = state.initial elif isinstance(state, State) and not isinstance(state, NestedState): raise ValueError("A passed state object must derive from NestedState! " "A default State object is not sufficient") else: raise ValueError("Cannot add state of type {0}. ".format(type(state).__name__)) def add_transition(self, trigger, source, dest, conditions=None, unless=None, before=None, after=None, prepare=None, **kwargs): if source != self.wildcard_all: source = [self.state_cls.separator.join(self._get_enum_path(s)) if isinstance(s, Enum) else s for s in listify(source)] if dest != self.wildcard_same: dest = self.state_cls.separator.join(self._get_enum_path(dest)) if isinstance(dest, Enum) else dest _super(HierarchicalMachine, self).add_transition(trigger, source, dest, conditions, unless, before, after, prepare, **kwargs) def get_global_name(self, state=None, join=True): domains = copy.copy(self.prefix_path) if state: state_name = state.name if hasattr(state, 'name') else state if state_name in self.states: domains.append(state_name) else: raise ValueError("State '{0}' not found in local states.".format(state)) return self.state_cls.separator.join(domains) if join else domains def get_nested_state_names(self): ordered_states = [] for state in self.states.values(): ordered_states.append(self.get_global_name(state)) with self(state.name): ordered_states.extend(self.get_nested_state_names()) return ordered_states def get_nested_transitions(self, trigger="", src_path=None, dest_path=None): if src_path and dest_path: src = self.state_cls.separator.join(src_path) dest = self.state_cls.separator.join(dest_path) transitions = _super(HierarchicalMachine, self).get_transitions(trigger, src, dest) if len(src_path) > 1 and len(dest_path) > 1: with self(src_path[0]): transitions.extend(self.get_nested_transitions(trigger, src_path[1:], dest_path[1:])) elif src_path: src = self.state_cls.separator.join(src_path) transitions = _super(HierarchicalMachine, self).get_transitions(trigger, src, "*") if len(src_path) > 1: with self(src_path[0]): transitions.extend(self.get_nested_transitions(trigger, src_path[1:], None)) elif dest_path: dest = self.state_cls.separator.join(dest_path) transitions = _super(HierarchicalMachine, self).get_transitions(trigger, "*", dest) if len(dest_path) > 1: for state_name in self.states: with self(state_name): transitions.extend(self.get_nested_transitions(trigger, None, dest_path[1:])) else: transitions = _super(HierarchicalMachine, self).get_transitions(trigger, "*", "*") for state_name in self.states: with self(state_name): transitions.extend(self.get_nested_transitions(trigger, None, None)) return transitions def get_nested_triggers(self, src_path=None): if src_path: triggers = _super(HierarchicalMachine, self).get_triggers(self.state_cls.separator.join(src_path)) if len(src_path) > 1 and src_path[0] in self.states: with self(src_path[0]): triggers.extend(self.get_nested_triggers(src_path[1:])) else: triggers = list(self.events.keys()) for state_name in self.states: with self(state_name): triggers.extend(self.get_nested_triggers()) return triggers def get_state(self, state, hint=None): """ Return the State instance with the passed name. """ if isinstance(state, Enum): state = self._get_enum_path(state) elif isinstance(state, string_types): state = state.split(self.state_cls.separator) if not hint: state = copy.copy(state) hint = copy.copy(state) if len(state) > 1: child = state.pop(0) try: with self(child): return self.get_state(state, hint) except (KeyError, ValueError): try: with self(): state = self for elem in hint: state = state.states[elem] return state except KeyError: raise ValueError("State '%s' is not a registered state." % self.state_cls.separator.join(hint)) elif state[0] not in self.states: raise ValueError("State '%s' is not a registered state." % state) return self.states[state[0]] def get_states(self, states): res = [] for state in states: if isinstance(state, list): res.append(self.get_states(state)) else: res.append(self.get_state(state)) return res def get_transitions(self, trigger="", source="*", dest="*", delegate=False): """ Return the transitions from the Machine. Args: trigger (str): Trigger name of the transition. source (str, State or Enum): Limits list to transitions from a certain state. dest (str, State or Enum): Limits list to transitions to a certain state. delegate (Optional[bool]): If True, consider delegations to parents of source """ with self(): source_path = [] if source == "*" \ else source.split(self.state_cls.separator) if isinstance(source, string_types) \ else self._get_enum_path(source) if isinstance(source, Enum) \ else self._get_state_path(source) dest_path = [] if dest == "*" \ else dest.split(self.state_cls.separator) if isinstance(dest, string_types) \ else self._get_enum_path(dest) if isinstance(dest, Enum) \ else self._get_state_path(dest) matches = self.get_nested_transitions(trigger, source_path, dest_path) # only consider delegations when source_path contains a nested state (len > 1) if delegate is False or len(source_path) < 2: return matches source_path.pop() while source_path: matches.extend(self.get_transitions(trigger, source=self.state_cls.separator.join(source_path), dest=dest)) source_path.pop() return matches def get_triggers(self, *args): """ Extends transitions.core.Machine.get_triggers to also include parent state triggers. """ triggers = [] with self(): for state in args: state_name = state.name if hasattr(state, 'name') else state state_path = state_name.split(self.state_cls.separator) if len(state_path) > 1: # we only need to check substates when 'state_name' refers to a substate with self(state_path[0]): triggers.extend(self.get_nested_triggers(state_path[1:])) while state_path: # check all valid transitions for parent states triggers.extend(_super(HierarchicalMachine, self).get_triggers(self.state_cls.separator.join(state_path))) state_path.pop() return triggers def has_trigger(self, trigger, state=None): """ Check whether an event/trigger is known to the machine Args: trigger (str): Event/trigger name state (optional[NestedState]): Limits the recursive search to this state and its children Returns: bool: True if event is known and False otherwise """ state = state or self return trigger in state.events or any([self.has_trigger(trigger, sta) for sta in state.states.values()]) def is_state(self, state_name, model, allow_substates=False): current_name = getattr(model, self.model_attribute) if allow_substates: if isinstance(current_name, Enum): current_name = self.state_cls.separator.join(self._get_enum_path(current_name)) if isinstance(state_name, Enum): state_name = self.state_cls.separator.join(self._get_enum_path(state_name)) return current_name.startswith(state_name) return current_name == state_name def on_enter(self, state_name, callback): """ Helper function to add callbacks to states in case a custom state separator is used. Args: state_name (str): Name of the state callback (str or callable): Function to be called. Strings will be resolved to model functions. """ self.get_state(state_name).add_callback('enter', callback) def on_exit(self, state_name, callback): """ Helper function to add callbacks to states in case a custom state separator is used. Args: state_name (str): Name of the state callback (str or callable): Function to be called. Strings will be resolved to model functions. """ self.get_state(state_name).add_callback('exit', callback) def set_state(self, states, model=None): """ Set the current state. Args: states (list of str or Enum or State): value of state(s) to be set model (optional[object]): targeted model; if not set, all models will be set to 'state' """ values = [self._set_state(value) for value in listify(states)] models = self.models if model is None else listify(model) for mod in models: setattr(mod, self.model_attribute, values if len(values) > 1 else values[0]) def to_state(self, model, state_name, *args, **kwargs): """ Helper function to add go to states in case a custom state separator is used. Args: model (class): The model that should be used. state_name (str): Name of the destination state. """ current_state = getattr(model, self.model_attribute) if isinstance(current_state, list): raise MachineError("Cannot use 'to_state' from parallel state") event = EventData(self.get_state(current_state), Event('to', self), self, model, args=args, kwargs=kwargs) if isinstance(current_state, Enum): event.source_path = self._get_enum_path(current_state) event.source_name = self.state_cls.separator.join(event.source_path) else: event.source_name = current_state event.source_path = current_state.split(self.state_cls.separator) self._create_transition(event.source_name, state_name).execute(event) def trigger_event(self, _model, _trigger, *args, **kwargs): """ Processes events recursively and forwards arguments if suitable events are found. This function is usually bound to models with model and trigger arguments already resolved as a partial. Execution will halt when a nested transition has been executed successfully. Args: _model (object): targeted model _trigger (str): event name *args: positional parameters passed to the event and its callbacks **kwargs: keyword arguments passed to the event and its callbacks Returns: bool: whether a transition has been executed successfully Raises: MachineError: When no suitable transition could be found and ignore_invalid_trigger is not True. Note that a transition which is not executed due to conditions is still considered valid. """ with self(): res = self._trigger_event(_model, _trigger, None, *args, **kwargs) return self._check_event_result(res, _model, _trigger) def _add_model_to_state(self, state, model): name = self.get_global_name(state) if self.state_cls.separator == '_': value = state.value if isinstance(state.value, Enum) else name self._checked_assignment(model, 'is_%s' % name, partial(self.is_state, value, model)) # Add dynamic method callbacks (enter/exit) if there are existing bound methods in the model # except if they are already mentioned in 'on_enter/exit' of the defined state for callback in self.state_cls.dynamic_methods: method = "{0}_{1}".format(callback, name) if hasattr(model, method) and inspect.ismethod(getattr(model, method)) and \ method not in getattr(state, callback): state.add_callback(callback[3:], method) else: path = name.split(self.state_cls.separator) value = state.value if isinstance(state.value, Enum) else name trig_func = partial(self.is_state, value, model) if hasattr(model, 'is_' + path[0]): getattr(model, 'is_' + path[0]).add(trig_func, path[1:]) else: self._checked_assignment(model, 'is_' + path[0], FunctionWrapper(trig_func, path[1:])) with self(state.name): for event in self.events.values(): if not hasattr(model, event.name): self._add_trigger_to_model(event.name, model) for state in self.states.values(): self._add_model_to_state(state, model) def _add_trigger_to_model(self, trigger, model): trig_func = partial(self.trigger_event, model, trigger) # FunctionWrappers are only necessary if a custom separator is used if trigger.startswith('to_') and self.state_cls.separator != '_': path = trigger[3:].split(self.state_cls.separator) if hasattr(model, 'to_' + path[0]): # add path to existing function wrapper getattr(model, 'to_' + path[0]).add(trig_func, path[1:]) else: # create a new function wrapper self._checked_assignment(model, 'to_' + path[0], FunctionWrapper(trig_func, path[1:])) else: self._checked_assignment(model, trigger, trig_func) # converts a list of current states into a hierarchical state tree def _build_state_tree(self, model_states, separator, tree=None): tree = tree if tree is not None else OrderedDict() if isinstance(model_states, list): for state in model_states: _ = self._build_state_tree(state, separator, tree) else: tmp = tree if isinstance(model_states, (Enum, EnumMeta)): with self(): path = self._get_enum_path(model_states) else: path = model_states.split(separator) for elem in path: tmp = tmp.setdefault(elem.name if hasattr(elem, 'name') else elem, OrderedDict()) return tree def _get_enum_path(self, enum_state, prefix=[]): if enum_state.name in self.states and self.states[enum_state.name].value == enum_state: return prefix + [enum_state.name] for name in self.states: with self(name): res = self._get_enum_path(enum_state, prefix=prefix + [name]) if res: return res return [] def _get_state_path(self, state, prefix=[]): if state in self.states.values(): return prefix + [state.name] for name in self.states: with self(name): res = self._get_state_path(state, prefix=prefix + [name]) if res: return res return [] def _check_event_result(self, res, model, trigger): if res is None: state_names = getattr(model, self.model_attribute) msg = "%sCan't trigger event '%s' from state(s) %s!" % (self.name, trigger, state_names) for state_name in listify(state_names): state = self.get_state(state_name) ignore = state.ignore_invalid_triggers if state.ignore_invalid_triggers is not None \ else self.ignore_invalid_triggers if not ignore: # determine whether a MachineError (valid event but invalid state) ... if self.has_trigger(trigger): raise MachineError(msg) # or AttributeError (invalid event) is appropriate else: raise AttributeError("Do not know event named '%s'." % trigger) _LOGGER.warning(msg) res = False return res def _get_trigger(self, model, trigger_name, *args, **kwargs): """Convenience function added to the model to trigger events by name. Args: model (object): Model with assigned event trigger. trigger_name (str): Name of the trigger to be called. *args: Variable length argument list which is passed to the triggered event. **kwargs: Arbitrary keyword arguments which is passed to the triggered event. Returns: bool: True if a transitions has been conducted or the trigger event has been queued. """ return self.trigger_event(model, trigger_name, *args, **kwargs) def _has_state(self, state, raise_error=False): """ This function Args: state (NestedState): state to be tested raise_error (bool): whether ValueError should be raised when the state is not registered Returns: bool: Whether state is registered in the machine Raises: ValueError: When raise_error is True and state is not registered """ found = _super(HierarchicalMachine, self)._has_state(state) if not found: for a_state in self.states: with self(a_state): if self._has_state(state): return True if not found and raise_error: msg = 'State %s has not been added to the machine' % (state.name if hasattr(state, 'name') else state) raise ValueError(msg) return found def _init_state(self, state): for model in self.models: self._add_model_to_state(state, model) if self.auto_transitions: state_name = self.get_global_name(state.name) parent = state_name.split(self.state_cls.separator, 1) with self(): for a_state in self.get_nested_state_names(): if a_state == parent[0]: self.add_transition('to_%s' % state_name, self.wildcard_all, state_name) elif len(parent) == 1: self.add_transition('to_%s' % a_state, state_name, a_state) with self(state.name): for substate in self.states.values(): self._init_state(substate) def _recursive_initial(self, value): if isinstance(value, string_types): path = value.split(self.state_cls.separator, 1) if len(path) > 1: state_name, suffix = path # make sure the passed state has been created already _super(HierarchicalMachine, self.__class__).initial.fset(self, state_name) with self(state_name): self.initial = suffix self._initial = state_name + self.state_cls.separator + self._initial else: _super(HierarchicalMachine, self.__class__).initial.fset(self, value) elif isinstance(value, (list, tuple)): return [self._recursive_initial(v) for v in value] else: _super(HierarchicalMachine, self.__class__).initial.fset(self, value) return self._initial[0] if isinstance(self._initial, list) and len(self._initial) == 1 else self._initial def _resolve_initial(self, models, state_name_path, prefix=[]): if state_name_path: state_name = state_name_path.pop(0) with self(state_name): return self._resolve_initial(models, state_name_path, prefix=prefix + [state_name]) if self.scoped.initial: entered_states = [] for initial_state_name in listify(self.scoped.initial): with self(initial_state_name): entered_states.append(self._resolve_initial(models, [], prefix=prefix + [self.scoped.name])) return entered_states if len(entered_states) > 1 else entered_states[0] return self.state_cls.separator.join(prefix) def _set_state(self, state_name): if isinstance(state_name, list): return [self._set_state(value) for value in state_name] else: a_state = self.get_state(state_name) return a_state.value if isinstance(a_state.value, Enum) else state_name def _trigger_event(self, _model, _trigger, _state_tree, *args, **kwargs): if _state_tree is None: _state_tree = self._build_state_tree(listify(getattr(_model, self.model_attribute)), self.state_cls.separator) res = {} for key, value in _state_tree.items(): if value: with self(key): tmp = self._trigger_event(_model, _trigger, value, *args, **kwargs) if tmp is not None: res[key] = tmp if res.get(key, False) is False and _trigger in self.events: tmp = self.events[_trigger].trigger(_model, self, *args, **kwargs) if tmp is not None: res[key] = tmp return None if not res or all(v is None for v in res.values()) else any(res.values())