Event Bus

eventbus/defaulteventbus.gd

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+class_name DefaultEventBus
+extends EventBus
+
+var subscribers: Dictionary = {}
+
+func _init():
+	subscribers = {}
+
+func subscribers_of(event_scope: EventScope, event_type: String) -> Array[Subscription]:
+	var key = [event_scope, event_type]
+	return subscribers.get(key, [])
+
+func subscribe_to(event_scope: EventScope, event_type: String, fn: Callable) -> Subscription:
+	var key = [event_scope, event_type]
+	var subscriber_set: Array[EventBusSubscription] = subscribers.get(key, [] as Array[EventBusSubscription])
+	var subscription = EventBusSubscription.new(key, fn, self)
+	subscriber_set.append(subscription)
+	subscribers[key] = subscriber_set
+	return subscription
+
+func publish(event_scope: EventScope, event: Event) -> void:
+	var key = [event_scope, event.get_type()]
+	var subscriber_set: Array[EventBusSubscription] = subscribers.get(key, [] as Array[EventBusSubscription]).duplicate(true)
+	for subscriber in subscriber_set:
+		var result = subscriber.callback.call(event)
+		if result == EventResult.ResultType.DISPOSE_SUBSCRIPTION:
+			subscriber.dispose()
+
+func cancel_scope(event_scope: EventScope) -> void:
+	var keys_to_cancel: Array = []
+	for key in subscribers.keys():
+		if key[0] == event_scope:
+			keys_to_cancel.append(key)
+	for key in keys_to_cancel:
+		var subscriber_set: Array[EventBusSubscription] = subscribers[key]
+		for subscriber in subscriber_set:
+			subscriber.dispose()
+
+func dispose() -> void:
+	for subscriber_set in subscribers.values():
+		for subscriber in subscriber_set:
+			subscriber.dispose()
+	subscribers.clear()

eventbus/defaultscope.gd

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+class_name DefaultScope
+extends EventScope

eventbus/event.gd

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+class_name Event
+extends RefCounted
+
+var type: String
+var source: Variant
+
+func _init(_source: Variant = null):
+	source = _source
+	type = self.get_class()
+
+func get_type() -> String:
+	return type

eventbus/eventbus.gd

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+class_name EventBus
+extends Node
+
+func subscribers_of(_event_scope: EventScope, _event_type: String) -> Array[Subscription]:
+	return Array()
+
+func subscribe_to(_event_scope: EventScope, _event_type: String, _fn: Callable) -> Subscription:
+	return Subscription.new()
+
+func publish(_event_scope: EventScope, _event: Event) -> void:
+	pass
+
+func cancel_scope(_event_scope: EventScope) -> void:
+	pass
+
+func dispose() -> void:
+	pass

eventbus/eventbussubscription.gd

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+class_name EventBusSubscription
+extends Subscription
+
+var key: Array
+var callback: Callable
+var bus: DefaultEventBus
+
+func _init(_key: Array, _callback: Callable, _bus: DefaultEventBus):
+	key = _key
+	callback = _callback
+	bus = _bus
+
+func dispose() -> void:
+	var subscriber_set: Array[EventBusSubscription] = bus.subscribers.get(key, [])
+	subscriber_set.erase(self)
+	if subscriber_set.is_empty():
+		bus.subscribers.erase(key)
+	else:
+		bus.subscribers[key] = subscriber_set

eventbus/eventresult.gd

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+class_name EventResult
+extends RefCounted
+
+enum ResultType {
+	KEEP_SUBSCRIPTION,
+	DISPOSE_SUBSCRIPTION
+}

eventbus/eventscope.gd

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+class_name EventScope
+extends Node

eventbus/subscription.gd

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+class_name Subscription
+extends RefCounted
+
+func dispose() -> void:
+	pass