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Hat statechart engine

Project description

This library is part of Hat Open project - open-source framework of tools and libraries for developing applications used for remote monitoring, control and management of intelligent electronic devices such as IoT devices, PLCs, industrial automation or home automation systems.

Development of Hat Open and associated repositories is sponsored by Končar - Power Plant and Electric Traction Engineering Inc. (Končar KET -

For more information see:


Hierarchical state machine library with support for SCXML and Graphviz visualization:

EventName = str
"""Event name"""

StateName = str
"""State name"""

ActionName = str
"""Action name"""

ConditionName = str
"""Condition name"""

class Event(typing.NamedTuple):
    name: EventName
    payload: typing.Any = None

class Transition(typing.NamedTuple):
    event: EventName
    target: typing.Optional[StateName]
    actions: typing.List[ActionName] = []
    conditions: typing.List[ConditionName] = []
    internal: bool = False

class State(typing.NamedTuple):
    name: StateName
    children: typing.List['State'] = []
    transitions: typing.List[Transition] = []
    entries: typing.List[ActionName] = []
    exits: typing.List[ActionName] = []
    final: bool = False

Action = typing.Callable[[typing.Optional[Event]], None]
"""Action function"""

Condition = typing.Callable[[typing.Optional[Event]], bool]
"""Condition function"""

class Statechart:
    """Statechart engine"""

    def __init__(self,
                 states: typing.Iterable[State],
                 actions: typing.Dict[str, Action],
                 conditions: typing.Dict[str, Condition] = {}): ...

    def state(self) -> typing.Optional[StateName]:
        """Current state"""

    def register(self, event: Event):
        """Add event to queue"""

    async def run(self):
        """Run statechart"""

def parse_scxml(scxml: typing.Union[typing.TextIO, pathlib.Path]
                ) -> typing.List[State]:
    """Parse SCXML"""

def create_dot_graph(states: typing.Iterable[State]) -> str:
    """Create DOT representation of statechart"""

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