# -*- coding: utf-8 -*- """ transitions.extensions.nesting ------------------------------ Implements a hierarchical state machine based on transitions.core.Machine. Supports nested states, parallel states and the composition of multiple hierarchical state machines. """ from collections import OrderedDict import copy from functools import partial, reduce import inspect import logging try: # Enums are supported for Python 3.4+ and Python 2.7 with enum34 package installed from enum import Enum, EnumMeta except ImportError: # pragma: no cover # If enum is not available, create dummy classes for type checks class Enum: # type: ignore """This is just an Enum stub for Python 2 and Python 3.3 and before without Enum support.""" class EnumMeta: # type: ignore """This is just an EnumMeta stub for Python 2 and Python 3.3 and before without Enum support.""" from six import string_types from ..core import State, Machine, Transition, Event, listify, MachineError, EventData _LOGGER = logging.getLogger(__name__) _LOGGER.addHandler(logging.NullHandler()) # converts a hierarchical tree into a list of current states def _build_state_list(state_tree, separator, prefix=None): prefix = prefix or [] 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] def resolve_order(state_tree): """Converts a (model) state tree into a list of state paths. States are ordered in the way in which states should be visited to process the event correctly (Breadth-first). This makes sure that ALL children are evaluated before parents in parallel states. Args: state_tree (dict): A dictionary representation of the model's state. Returns: list of lists of str representing the order of states to be processed. """ queue = [] res = [] prefix = [] while True: for state_name in reversed(list(state_tree.keys())): scope = prefix + [state_name] res.append(scope) if state_tree[state_name]: queue.append((scope, state_tree[state_name])) if not queue: break prefix, state_tree = queue.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): """ Args: func: Function to be called at the end of the path. path: If path is an empty string, assign function """ 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 (list of strings): Remaining segment of the substate path. """ if not path: self._func = func else: name = path[0] if name[0].isdigit(): name = 's' + name if hasattr(self, name): getattr(self, name).add(func, path[1:]) else: assert not path[1:], "nested path should be empty" setattr(self, name, FunctionWrapper(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, *args, **kwargs): raise RuntimeError("NestedEvent.trigger must not be called directly. Call Machine.trigger_event instead.") def trigger_nested(self, event_data): """Executes all transitions that match the current state, halting as soon as one successfully completes. 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: event_data (NestedEventData): The currently processed event Returns: boolean indicating whether or not a transition was successfully executed (True if successful, False if not). """ machine = event_data.machine model = event_data.model 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() event_data.event = self 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: event_data.state = machine.get_state(state_name) event_data.source_name = state_name event_data.source_path = copy.copy(state_path) self._process(event_data) if event_data.result: elems = state_path while elems: done.add(machine.state_cls.separator.join(elems)) elems.pop() return event_data.result 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) for trans in self.transitions[event_data.source_name]: event_data.transition = trans event_data.result = trans.execute(event_data) if event_data.result: break class NestedEventData(EventData): """Collection of relevant data related to the ongoing nested transition attempt.""" def __init__(self, state, event, machine, model, args, kwargs): super(NestedEventData, self).__init__(state, event, machine, model, args, kwargs) self.source_path = None self.source_name = None 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. """ 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). """ dynamic_methods = State.dynamic_methods + ["on_final"] def __init__(self, name, on_enter=None, on_exit=None, ignore_invalid_triggers=None, final=False, initial=None, on_final=None): super(NestedState, self).__init__(name=name, on_enter=on_enter, on_exit=on_exit, ignore_invalid_triggers=ignore_invalid_triggers, final=final) self.initial = initial self.events = {} self.states = OrderedDict() self.on_final = listify(on_final) 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 state to add to the current state. """ for state in listify(states): self.states[state.name] = state def scoped_enter(self, event_data, scope=None): """Enters a state with the provided scope. Args: event_data (NestedEventData): The currently processed event. scope (list(str)): Names of the state's parents starting with the top most parent. """ self._scope = scope or [] try: self.enter(event_data) finally: self._scope = [] def scoped_exit(self, event_data, scope=None): """Exits a state with the provided scope. Args: event_data (NestedEventData): The currently processed event. scope (list(str)): Names of the state's parents starting with the top most parent. """ self._scope = scope or [] 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.""" def _resolve_transition(self, event_data): dst_name_path = self.dest.split(event_data.machine.state_cls.separator) _ = event_data.machine.get_state(dst_name_path) state_tree = event_data.machine.build_state_tree( listify(getattr(event_data.model, event_data.machine.model_attribute)), event_data.machine.state_cls.separator) scope = event_data.machine.get_global_name(join=False) 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 # when destination is empty this means we are already in the state we want to enter # we deal with a reflexive transition here or a sibling state that has already been entered # as internal transitions have been already dealt with # the 'root' of src and dest will be set to the parent and dst (and src) substate will be set as destination if not dst_name_path: dst_name_path = [root.pop()] scoped_tree = reduce(dict.get, scope + root, state_tree) # if our scope is a parallel state we need to narrow down the exit scope to the targeted sibling if len(scoped_tree) > 1: exit_scope = {dst_name_path[0]: scoped_tree.get(dst_name_path[0])} else: exit_scope = scoped_tree exit_partials = [partial(event_data.machine.get_state(root + state_name).scoped_exit, event_data, scope + root + state_name[:-1]) for state_name in resolve_order(exit_scope)] new_states, enter_partials = self._enter_nested(root, dst_name_path, scope + root, event_data) # we reset/clear the whole branch if it is scoped, otherwise only reset the sibling if exit_scope == scoped_tree: 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() with event_data.machine(): on_final_cbs, _ = self._final_check(event_data, state_tree, enter_partials) for on_final_cb in on_final_cbs: on_final_cb() def _final_check(self, event_data, state_tree, enter_partials): on_final_cbs = [] is_final = False # processes states with children if state_tree: all_children_final = True for child_cbs, is_final in (self._final_check_nested(state, event_data, state_tree, enter_partials) for state in state_tree): # if one child is not considered final, processing can stop if not is_final: all_children_final = False # if one child has recently transitioned to a final state, we need to update all parents on_final_cbs.extend(child_cbs) # if and only if all other children are also in a final state and a child has recently reached a final # state OR the scoped state has just been entered, trigger callbacks if all_children_final: if on_final_cbs or any(event_data.machine.scoped.scoped_enter == part.func for part in enter_partials): on_final_cbs.append( partial(event_data.machine.callbacks, event_data.machine.scoped.on_final, event_data)) is_final = True # if a state is a leaf state OR has children not in a final state elif getattr(event_data.machine.scoped, 'final', False): # if the state itself is considered final and has recently been entered trigger callbacks # thus, a state with non-final children may still trigger callbacks if itself is considered final if any(event_data.machine.scoped.scoped_enter == part.func for part in enter_partials): on_final_cbs.append(partial(event_data.machine.callbacks, event_data.machine.scoped.on_final, event_data)) is_final = True return on_final_cbs, is_final def _final_check_nested(self, state, event_data, state_tree, enter_partials): with event_data.machine(state): return self._final_check(event_data, state_tree[state], enter_partials) 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 = [] queue = [] 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: queue.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 queue: break scoped_tree, prefix, initial_states = queue.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) # Note: When conditions are handled like other dynamic callbacks the key == "conditions" clause can be removed 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 or key == "conditions": 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, model=Machine.self_literal, states=None, initial='initial', transitions=None, send_event=False, auto_transitions=True, ordered_transitions=False, ignore_invalid_triggers=None, before_state_change=None, after_state_change=None, name=None, queued=False, prepare_event=None, finalize_event=None, model_attribute='state', model_override=False, on_exception=None, on_final=None, **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 self._next_scope = None super(HierarchicalMachine, self).__init__( model=model, states=states, initial=initial, transitions=transitions, send_event=send_event, auto_transitions=auto_transitions, ordered_transitions=ordered_transitions, ignore_invalid_triggers=ignore_invalid_triggers, before_state_change=before_state_change, after_state_change=after_state_change, name=name, queued=queued, prepare_event=prepare_event, finalize_event=finalize_event, model_attribute=model_attribute, model_override=model_override, on_exception=on_exception, on_final=on_final, **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 HierarchicalMachine): 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): self._add_string_state(state, on_enter, on_exit, ignore, remap, **kwargs) elif isinstance(state, Enum): self._add_enum_state(state, on_enter, on_exit, ignore, remap, **kwargs) elif isinstance(state, dict): self._add_dict_state(state, ignore, remap, **kwargs) 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, HierarchicalMachine): self._add_machine_states(state, remap) 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 and dest == self.wildcard_same: source = self.get_nested_state_names() else: 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): """Returns the name of the passed state in context of the current prefix/scope. Args: state (str, Enum or NestedState): The state to be analyzed. join (bool): Whether this method should join the path elements or not Returns: str or list(str) of the global state name """ 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): """Returns a list of global names of all states of a machine. Returns: list(str) of global state names. """ 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): """Retrieves a list of all transitions matching the passed requirements. Args: trigger (str): If set, return only transitions related to this trigger. src_path (list(str)): If set, return only transitions with this source state. dest_path (list(str)): If set, return only transitions with this destination. Returns: list(NestedTransitions) of valid transitions. """ 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): """Retrieves a list of valid triggers. Args: src_path (list(str)): A list representation of the source state's name. Returns: list(str) of valid trigger names. """ 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. Args: state (str, Enum or list(str)): A state name, enum or state path hint (list(str)): A state path to check for the state in question Returns: NestedState that belongs to the passed str (list) or Enum. """ 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) ) # from KeyError 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): """Retrieves a list of NestedStates. Args: states (str, Enum or list of str or Enum): Names/values of the states to retrieve. Returns: list(NestedStates) belonging to the passed identifiers. """ 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 Returns: list(NestedTransitions): All transitions matching the request. """ 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_nested_transitions(trigger, src_path=source_path, dest_path=dest_path)) source_path.pop() return matches def _remove_nested_transitions(self, trigger, src_path, dest_path): """Remove transitions from nested states. Args: trigger (str): Trigger name of the transition to be removed. src_path (list(str)): If empty, all transitions that match dest_path and trigger will be removed. dest_path (list(str)): If empty, all transitions that match src_path and trigger will be removed. """ cur_src = self.state_cls.separator.join(src_path) cur_dst = self.state_cls.separator.join(dest_path) if trigger in self.scoped.events: evt = self.scoped.events[trigger] for src, transitions in evt.transitions.items(): evt.transitions[src] = [trans for trans in transitions if (src_path and trans.source != cur_src) or (cur_dst and trans.dest != cur_dst)] for state_name in self.scoped.states: with self(state_name): if state_name in [cur_src, cur_dst]: continue self._remove_nested_transitions(trigger, src_path if not src_path or state_name != src_path[0] else src_path[1:], dest_path if not dest_path or state_name != dest_path[0] else dest_path[1:]) def remove_transition(self, trigger, source="*", dest="*"): """Removes transitions matching the passed criteria. 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. """ 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) self._remove_nested_transitions(trigger, source_path, dest_path) # remove trigger from models if no transition is left for trigger if not self.get_transitions(trigger): for model in self.models: delattr(model, trigger) def _can_trigger(self, model, trigger, *args, **kwargs): state_tree = self.build_state_tree(getattr(model, self.model_attribute), self.state_cls.separator) ordered_states = resolve_order(state_tree) with self(): return any( self._can_trigger_nested(model, trigger, state_path, *args, **kwargs) for state_path in ordered_states ) def _can_trigger_nested(self, model, trigger, path, *args, **kwargs): if trigger in self.events: source_path = copy.copy(path) while source_path: event_data = EventData(self.get_state(source_path), Event(name=trigger, machine=self), self, model, args, kwargs) state_name = self.state_cls.separator.join(source_path) for transition in self.events[trigger].transitions.get(state_name, []): try: _ = self.get_state(transition.dest) if transition.dest is not None else transition.source except ValueError: continue event_data.transition = transition try: self.callbacks(self.prepare_event, event_data) self.callbacks(transition.prepare, event_data) if all(c.check(event_data) for c in transition.conditions): return True except BaseException as err: event_data.error = err if self.on_exception: self.callbacks(self.on_exception, event_data) else: raise source_path.pop(-1) if path: with self(path.pop(0)): return self._can_trigger_nested(model, trigger, path, *args, **kwargs) return False 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, model, allow_substates=False): tree = self.build_state_tree(listify(getattr(model, self.model_attribute)), self.state_cls.separator) path = self._get_enum_path(state) if isinstance(state, Enum) else state.split(self.state_cls.separator) for elem in path: if elem not in tree: return False tree = tree[elem] return len(tree) == 0 or allow_substates 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, state, model=None): """Set the current state. Args: state (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(state)] 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 = NestedEventData(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. """ event_data = NestedEventData(state=None, event=None, machine=self, model=model, args=args, kwargs=kwargs) event_data.result = None return self._process(partial(self._trigger_event, event_data, trigger)) def _trigger_event(self, event_data, trigger): try: with self(): res = self._trigger_event_nested(event_data, trigger, None) event_data.result = self._check_event_result(res, event_data.model, trigger) except BaseException as err: # pylint: disable=broad-except; Exception will be handled elsewhere event_data.error = err if self.on_exception: self.callbacks(self.on_exception, event_data) else: raise finally: try: self.callbacks(self.finalize_event, event_data) _LOGGER.debug("%sExecuted machine finalize callbacks", self.name) except BaseException as err: # pylint: disable=broad-except; Exception will be handled elsewhere _LOGGER.error("%sWhile executing finalize callbacks a %s occurred: %s.", self.name, type(err).__name__, str(err)) return event_data.result 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: assert not path[1:], "nested path should be empty" self._checked_assignment(model, 'is_' + path[0], FunctionWrapper(trig_func)) with self(state.name): for event in self.events.values(): self._add_trigger_to_model(event.name, model) for a_state in self.states.values(): self._add_model_to_state(a_state, model) def _add_dict_state(self, state, ignore_invalid_triggers, remap, **kwargs): 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_invalid_triggers # 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 transitions: self.add_transitions(transitions) if remap is not None: remapped_transitions.extend(self._remap_state(new_state, remap)) self.add_transitions(remapped_transitions) def _add_enum_state(self, state, on_enter, on_exit, ignore_invalid_triggers, remap, **kwargs): if remap is not None and state.name in remap: return 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 state.name in self.states: raise ValueError("State {0} cannot be added since it already exists.".format(state.name)) new_state = self._create_state(state, on_enter=on_enter, on_exit=on_exit, ignore_invalid_triggers=ignore_invalid_triggers, **kwargs) self.states[new_state.name] = new_state self._init_state(new_state) def _add_machine_states(self, state, remap): new_states = [s for s in state.states.values() if remap is None or (s.name if hasattr(s, "name") else s) not in remap] self.add_states(new_states) for evt in state.events.values(): # skip auto transitions if state.auto_transitions and evt.name.startswith('to_') and evt.name[3:] in state.states: continue if evt.transitions and evt.name not in self.events: self.events[evt.name] = evt for model in self.models: self._add_trigger_to_model(evt.name, model) if self.scoped.initial is None: self.scoped.initial = state.initial def _add_string_state(self, state, on_enter, on_exit, ignore_invalid_triggers, remap, **kwargs): 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_invalid_triggers, **kwargs) self.states[new_state.name] = new_state self._init_state(new_state) def _add_trigger_to_model(self, trigger, model): trig_func = partial(self.trigger_event, model, trigger) self._add_may_transition_func_for_trigger(trigger, model) # 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)) else: self._checked_assignment(model, trigger, trig_func) def build_state_tree(self, model_states, separator, tree=None): """Converts a list of current states into a hierarchical state tree. Args: model_states (str or list(str)): separator (str): The character used to separate state names tree (OrderedDict): The current branch to use. If not passed, create a new tree. Returns: OrderedDict: A state tree dictionary """ 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=None): prefix = prefix or [] 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 # if we reach this point without a prefix, we looped over all nested states # and could not find a suitable enum state if not prefix: raise ValueError("Could not find path of {0}.".format(enum_state)) return None def _get_state_path(self, state, prefix=None): prefix = prefix or [] 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 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 _remap_state(self, state, remap): drop_event = [] remapped_transitions = [] 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': 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 d_trans in drop_trans: trans_source.remove(d_trans) if not trans_source: drop_source.append(source_name) for d_source in drop_source: del event.transitions[d_source] if not event.transitions: drop_event.append(trigger) for d_event in drop_event: del self.events[d_event] return remapped_transitions def _resolve_initial(self, models, state_name_path, prefix=None): prefix = prefix or [] 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] a_state = self.get_state(state_name) return a_state.value if isinstance(a_state.value, Enum) else state_name def _trigger_event_nested(self, event_data, trigger, _state_tree): model = event_data.model 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_nested(event_data, trigger, value) if tmp is not None: res[key] = tmp if res.get(key, False) is False and trigger in self.events: event_data.event = self.events[trigger] tmp = event_data.event.trigger_nested(event_data) 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())