Source code for hikari.api.event_manager

# -*- coding: utf-8 -*-
# cython: language_level=3
# Copyright (c) 2020 Nekokatt
# Copyright (c) 2021-present davfsa
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"""Core interface for components that manage events in the library."""
from __future__ import annotations

__all__: typing.Sequence[str] = ("EventManager", "EventStream")

import abc
import asyncio
import typing

from hikari import iterators
from hikari.events import base_events

if typing.TYPE_CHECKING:
    import types

    from hikari.api import shard as gateway_shard
    from hikari.internal import data_binding

    PredicateT = typing.Callable[[base_events.EventT], bool]
    CallbackT = typing.Callable[[base_events.EventT], typing.Coroutine[typing.Any, typing.Any, None]]
    ConsumerT = typing.Callable[
        [gateway_shard.GatewayShard, data_binding.JSONObject], typing.Coroutine[typing.Any, typing.Any, None]
    ]

    _EventStreamT = typing.TypeVar("_EventStreamT")


[docs]class EventStream(iterators.LazyIterator[base_events.EventT], abc.ABC): """A base abstract class for all event streamers. Unlike `hikari.iterators.LazyIterator` (which this extends), an event streamer must be started and closed. Examples -------- A streamer may either be started and closed using `with` syntax where `EventStream.open` and `EventStream.close` are implicitly called based on context. .. code-block:: python with EventStream(app, EventType, timeout=50) as stream: async for entry in stream: ... A streamer may also be directly started and closed using the `EventStream.close` and `EventStream.open`. Note that if you don't call `EventStream.close` after opening a streamer when you're finished with it then it may queue events events in memory indefinitely. .. code-block:: python stream = EventStream(app, EventType, timeout=50) await stream.open() async for event in stream: ... await stream.close() See Also -------- LazyIterator : `hikari.iterators.LazyIterator`. """ __slots__: typing.Sequence[str] = () @abc.abstractmethod
[docs] def close(self) -> None: """Mark this streamer as closed to stop it from queueing and receiving events. If called on an already closed streamer then this will do nothing. .. note:: `with streamer` may be used as a short-cut for opening and closing a streamer. """
@abc.abstractmethod
[docs] def open(self) -> None: """Mark this streamer as opened to let it start receiving and queueing events. If called on an already started streamer then this will do nothing. .. note:: `with streamer` may be used as a short-cut for opening and closing a stream. """
@abc.abstractmethod
[docs] def filter( self: _EventStreamT, *predicates: typing.Union[typing.Tuple[str, typing.Any], typing.Callable[[base_events.EventT], bool]], **attrs: typing.Any, ) -> _EventStreamT: """Filter the items by one or more conditions. Each condition is treated as a predicate, being called with each item that this iterator would return when it is requested. All conditions must evaluate to `True` for the item to be returned. If this is not met, then the item is discarded and ignored, the next matching item will be returned instead, if there is one. Parameters ---------- *predicates : typing.Union[typing.Callable[[ValueT], bool], typing.Tuple[str, typing.Any]] Predicates to invoke. These are functions that take a value and return `True` if it is of interest, or `False` otherwise. These may instead include 2-`tuple` objects consisting of a `str` attribute name (nested attributes are referred to using the ``.`` operator), and values to compare for equality. This allows you to specify conditions such as `members.filter(("user.bot", True))`. **attrs : typing.Any Alternative to passing 2-tuples. Cannot specify nested attributes using this method. Returns ------- EventStream[ValueT] The current stream with the new filter applied. """
@abc.abstractmethod def __enter__(self: _EventStreamT) -> _EventStreamT: raise NotImplementedError @abc.abstractmethod def __exit__( self, exc_type: typing.Optional[typing.Type[BaseException]], exc: typing.Optional[BaseException], exc_tb: typing.Optional[types.TracebackType], ) -> None: raise NotImplementedError
[docs]class EventManager(abc.ABC): """Base interface for event manager implementations. This is a listener of a `hikari.events.base_events.Event` object and consumer of raw event payloads, and is expected to invoke one or more corresponding event listeners where appropriate. """ __slots__: typing.Sequence[str] = () @abc.abstractmethod
[docs] def consume_raw_event( self, event_name: str, shard: gateway_shard.GatewayShard, payload: data_binding.JSONObject ) -> None: """Consume a raw event. Parameters ---------- event_name : str The case-insensitive name of the event being triggered. shard : hikari.api.shard.GatewayShard Object of the shard that received this event. payload : hikari.internal.data_binding.JSONObject Payload of the event being triggered. Raises ------ LookupError If there is no consumer for the event. """
@abc.abstractmethod
[docs] def dispatch(self, event: base_events.Event) -> asyncio.Future[typing.Any]: """Dispatch an event. Parameters ---------- event : hikari.events.base_events.Event The event to dispatch. Examples -------- We can dispatch custom events by first defining a class that derives from `hikari.events.base_events.Event`. .. code-block:: python import attr from hikari.traits import RESTAware from hikari.events.base_events import Event from hikari.users import User from hikari.snowflakes import Snowflake @attr.define() class EveryoneMentionedEvent(Event): app: RESTAware = attr.field() author: User = attr.field() '''The user who mentioned everyone.''' content: str = attr.field() '''The message that was sent.''' message_id: Snowflake = attr.field() '''The message ID.''' channel_id: Snowflake = attr.field() '''The channel ID.''' We can then dispatch our event as we see fit. .. code-block:: python from hikari.events.messages import MessageCreateEvent @bot.listen(MessageCreateEvent) async def on_message(event): if "@everyone" in event.content or "@here" in event.content: event = EveryoneMentionedEvent( author=event.author, content=event.content, message_id=event.id, channel_id=event.channel_id, ) bot.dispatch(event) This event can be listened to elsewhere by subscribing to it with `EventManager.subscribe`. .. code-block:: python @bot.listen(EveryoneMentionedEvent) async def on_everyone_mentioned(event): print(event.user, "just pinged everyone in", event.channel_id) Returns ------- asyncio.Future[typing.Any] A future that can be optionally awaited. If awaited, the future will complete once all corresponding event listeners have been invoked. If not awaited, this will schedule the dispatch of the events in the background for later. See Also -------- Listen : `hikari.api.event_manager.EventManager.listen`. Stream : `hikari.api.event_manager.EventManager.stream`. Subscribe : `hikari.api.event_manager.EventManager.subscribe`. Unsubscribe : `hikari.api.event_manager.EventManager.unsubscribe`. Wait_for: `hikari.api.event_manager.EventManager.wait_for`. """
# Yes, this is not generic. The reason for this is MyPy complains about # using ABCs that are not concrete in generic types passed to functions. # For the sake of UX, I will check this at runtime instead and let the # user use a static type checker. @abc.abstractmethod
[docs] def subscribe(self, event_type: typing.Type[typing.Any], callback: CallbackT[typing.Any]) -> None: """Subscribe a given callback to a given event type. Parameters ---------- event_type : typing.Type[T] The event type to listen for. This will also listen for any subclasses of the given type. `T` must be a subclass of `hikari.events.base_events.Event`. callback Must be a coroutine function to invoke. This should consume an instance of the given event, or an instance of a valid subclass if one exists. Any result is discarded. Examples -------- The following demonstrates subscribing a callback to message creation events. .. code-block:: python from hikari.events.messages import MessageCreateEvent async def on_message(event): ... bot.subscribe(MessageCreateEvent, on_message) See Also -------- Dispatch : `hikari.api.event_manager.EventManager.dispatch`. Listen : `hikari.api.event_manager.EventManager.listen`. Stream : `hikari.api.event_manager.EventManager.stream`. Unsubscribe : `hikari.api.event_manager.EventManager.unsubscribe`. Wait_for : `hikari.api.event_manager.EventManager.wait_for`. """
# Yes, this is not generic. The reason for this is MyPy complains about # using ABCs that are not concrete in generic types passed to functions. # For the sake of UX, I will check this at runtime instead and let the # user use a static type checker. @abc.abstractmethod
[docs] def unsubscribe(self, event_type: typing.Type[typing.Any], callback: CallbackT[typing.Any]) -> None: """Unsubscribe a given callback from a given event type, if present. Parameters ---------- event_type : typing.Type[T] The event type to unsubscribe from. This must be the same exact type as was originally subscribed with to be removed correctly. `T` must derive from `hikari.events.base_events.Event`. callback The callback to unsubscribe. Examples -------- The following demonstrates unsubscribing a callback from a message creation event. .. code-block:: python from hikari.events.messages import MessageCreateEvent async def on_message(event): ... bot.unsubscribe(MessageCreateEvent, on_message) See Also -------- Dispatch : `hikari.api.event_manager.EventManager.dispatch`. Listen : `hikari.api.event_manager.EventManager.listen`. Stream : `hikari.api.event_manager.EventManager.stream`. Subscribe : `hikari.api.event_manager.EventManager.subscribe`. Wait_for : `hikari.api.event_manager.EventManager.wait_for`. """
@abc.abstractmethod
[docs] def get_listeners( self, event_type: typing.Type[base_events.EventT], /, *, polymorphic: bool = True, ) -> typing.Collection[CallbackT[base_events.EventT]]: """Get the listeners for a given event type, if there are any. Parameters ---------- event_type : typing.Type[T] The event type to look for. `T` must be a subclass of `hikari.events.base_events.Event`. polymorphic : bool If `True`, this will also return the listeners for all the event types `event_type` will dispatch. If `False`, then only listeners for this class specifically are returned. The default is `True`. Returns ------- typing.Collection[typing.Callable[[T], typing.Coroutine[typing.Any, typing.Any, None]]] A copy of the collection of listeners for the event. Will return an empty collection if nothing is registered. """
@abc.abstractmethod
[docs] def listen( self, *event_types: typing.Type[base_events.EventT], ) -> typing.Callable[[CallbackT[base_events.EventT]], CallbackT[base_events.EventT]]: """Generate a decorator to subscribe a callback to an event type. This is a second-order decorator. Parameters ---------- *event_types : typing.Optional[typing.Type[T]] The event types to subscribe to. The implementation may allow this to be undefined. If this is the case, the event type will be inferred instead from the type hints on the function signature. `T` must be a subclass of `hikari.events.base_events.Event`. Returns ------- typing.Callable[[T], T] A decorator for a coroutine function that passes it to `EventManager.subscribe` before returning the function reference. See Also -------- Dispatch : `hikari.api.event_manager.EventManager.dispatch`. Stream : `hikari.api.event_manager.EventManager.stream`. Subscribe : `hikari.api.event_manager.EventManager.subscribe`. Unsubscribe : `hikari.api.event_manager.EventManager.unsubscribe`. Wait_for : `hikari.api.event_manager.EventManager.wait_for`. """
@abc.abstractmethod
[docs] def stream( self, event_type: typing.Type[base_events.EventT], /, timeout: typing.Union[float, int, None], limit: typing.Optional[int] = None, ) -> EventStream[base_events.EventT]: """Return a stream iterator for the given event and sub-events. .. warning:: If you use `await stream.open()` to start the stream then you must also close it with `await stream.close()` otherwise it may queue events in memory indefinitely. Parameters ---------- event_type : typing.Type[hikari.events.base_events.Event] The event type to listen for. This will listen for subclasses of this type additionally. timeout : typing.Optional[int, float] How long this streamer should wait for the next event before ending the iteration. If `None` then this will continue until explicitly broken from. limit : typing.Optional[int] The limit for how many events this should queue at one time before dropping extra incoming events, leave this as `None` for the cache size to be unlimited. Returns ------- EventStream[hikari.events.base_events.Event] The async iterator to handle streamed events. This must be started with `with stream:` or `stream.open()` before asynchronously iterating over it. Examples -------- .. code-block:: python with bot.stream(events.ReactionAddEvent, timeout=30).filter(("message_id", message.id)) as stream: async for user_id in stream.map("user_id").limit(50): ... or using `open()` and `close()` .. code-block:: python stream = bot.stream(events.ReactionAddEvent, timeout=30).filter(("message_id", message.id)) stream.open() async for user_id in stream.map("user_id").limit(50) ... stream.close() See Also -------- Dispatch : `hikari.api.event_manager.EventManager.dispatch`. Listen : `hikari.api.event_manager.EventManager.listen`. Subscribe : `hikari.api.event_manager.EventManager.subscribe`. Unsubscribe : `hikari.api.event_manager.EventManager.unsubscribe`. Wait_for : `hikari.api.event_manager.EventManager.wait_for`. """
@abc.abstractmethod
[docs] async def wait_for( self, event_type: typing.Type[base_events.EventT], /, timeout: typing.Union[float, int, None], predicate: typing.Optional[PredicateT[base_events.EventT]] = None, ) -> base_events.EventT: """Wait for a given event to occur once, then return the event. .. warning:: Async predicates are not supported. Parameters ---------- event_type : typing.Type[hikari.events.base_events.Event] The event type to listen for. This will listen for subclasses of this type additionally. predicate A function taking the event as the single parameter. This should return `True` if the event is one you want to return, or `False` if the event should not be returned. If left as `None` (the default), then the first matching event type that the bot receives (or any subtype) will be the one returned. timeout : typing.Union[float, int, None] The amount of time to wait before raising an `asyncio.TimeoutError` and giving up instead. This is measured in seconds. If `None`, then no timeout will be waited for (no timeout can result in "leaking" of coroutines that never complete if called in an uncontrolled way, so is not recommended). Returns ------- hikari.events.base_events.Event The event that was provided. Raises ------ asyncio.TimeoutError If the timeout is not `None` and is reached before an event is received that the predicate returns `True` for. See Also -------- Dispatch : `hikari.api.event_manager.EventManager.dispatch`. Listen : `hikari.api.event_manager.EventManager.listen`. Stream : `hikari.api.event_manager.EventManager.stream`. Subscribe : `hikari.api.event_manager.EventManager.subscribe`. Unsubscribe : `hikari.api.event_manager.EventManager.unsubscribe`. """