EventTree.lua

shared()

local Event = require("Event")

local EventTree = {}
EventTree.__index = EventTree

function EventTree.new()
	local self = setmetatable({
		_downstreamEvent = Event.new(),
		_upstreamEvent = Event.new()
	}, EventTree)

	self.Event = self._upstreamEvent

	return self
end

function EventTree:DispatchEvent(eventName, ...)
	self._upstreamEvent:Fire(eventName, ...)
end

function EventTree:HandleEvent(eventName, handler)
	local function eventFilter(targetEventName, ...)
		if targetEventName == eventName then
			handler(...)
		end
	end

	local downstreamConnection = self._downstreamEvent:Connect(eventFilter)
	local upstreamConnection = self._upstreamEvent:Connect(eventFilter)

	return function()
		downstreamConnection:Disconnect()
		upstreamConnection:Disconnect()
	end
end

function EventTree:Derive(id)
	local derivedEventTree = EventTree.new()

	derivedEventTree.Parent = self
	derivedEventTree._id = id

	derivedEventTree._parentDownstreamConnection = self._downstreamEvent:Connect(function(eventName, targetId, ...)
		if targetId == id then
			derivedEventTree._downstreamEvent:Fire(eventName, ...)
		end
	end)

	derivedEventTree._upstreamConnection = derivedEventTree._upstreamEvent:Connect(function(eventName, ...)
		self._upstreamEvent:Fire(eventName, id, ...)
	end)

	return derivedEventTree
end

function EventTree:DisconnectFromParent()
	assert(self.Parent, "This is a root EventTree!")

	self._parentDownstreamConnection:Disconnect()
	self._parentDownstreamConnection = nil
	self._upstreamConnection:Disconnect()
	self._upstreamConnection = nil

	self.Parent = nil
	self._id = nil
end

return EventTree