hikari/api/event_manager.py
# -*- coding: utf-8 -*-
# cython: language_level=3
# Copyright (c) 2020 Nekokatt
# Copyright (c) 2021-present davfsa
#
# Permission is hereby granted, free of charge, to any person obtaining a copy
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# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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# SOFTWARE.
"""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 typing_extensions import Self
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]
]
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 [`hikari.api.event_manager.EventStream.open`][] and
[`hikari.api.event_manager.EventStream.close`][] are implicitly called based on context.
```py
with EventStream(app, EventType, timeout=50) as stream:
async for entry in stream:
...
```
A streamer may also be directly started and closed using the [`hikari.api.event_manager.EventStream.close`][]
and [`hikari.api.event_manager.EventStream.open`][]. Note that if you don't call
[`hikari.api.event_manager.EventStream.close`][] after opening a streamer when
you're finished with it then it may queue events in memory indefinitely.
```py
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
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
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
def filter(
self,
*predicates: typing.Union[typing.Tuple[str, typing.Any], typing.Callable[[base_events.EventT], bool]],
**attrs: typing.Any,
) -> Self:
"""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
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
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) -> Self:
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
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
def consume_raw_event(
self, event_name: str, shard: gateway_shard.GatewayShard, payload: data_binding.JSONObject
) -> None:
"""Consume a raw event.
Parameters
----------
event_name
The case-insensitive name of the event being triggered.
shard
Object of the shard that received this event.
payload
Payload of the event being triggered.
Raises
------
LookupError
If there is no consumer for the event.
"""
@abc.abstractmethod
def dispatch(self, event: base_events.Event) -> asyncio.Future[typing.Any]:
"""Dispatch an event.
Parameters
----------
event
The event to dispatch.
Examples
--------
We can dispatch custom events by first defining a class that
derives from [`hikari.events.base_events.Event`][].
```py
import attrs
from hikari.traits import RESTAware
from hikari.events.base_events import Event
from hikari.users import User
from hikari.snowflakes import Snowflake
@attrs.define()
class EveryoneMentionedEvent(Event):
app: RESTAware = attrs.field()
author: User = attrs.field()
'''The user who mentioned everyone.'''
content: str = attrs.field()
'''The message that was sent.'''
message_id: Snowflake = attrs.field()
'''The message ID.'''
channel_id: Snowflake = attrs.field()
'''The channel ID.'''
```
We can then dispatch our event as we see fit.
```py
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
[`hikari.api.event_manager.EventManager.subscribe`][].
```py
@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
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
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.
```py
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
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
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.
```py
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
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
The event type to look for.
`T` must be a subclass of [`hikari.events.base_events.Event`][].
polymorphic
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
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
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
[`hikari.api.event_manager.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
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
The event type to listen for. This will listen for subclasses of
this type additionally.
timeout
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
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`][hikari.api.event_manager.EventStream.open]
before asynchronously iterating over it.
Examples
--------
```py
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()`
```py
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
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
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
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`][].
"""