From fa58e719d5fb5515e00f765f79fe920e4cb996fe Mon Sep 17 00:00:00 2001
From: Elias Fleckenstein <eliasfleckenstein@web.de>
Date: Fri, 6 Aug 2021 23:19:34 +0200
Subject: [PATCH] Add Event and EventTarget

---
 README.md    |  2 +-
 events.lua   | 61 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 init.lua     |  1 +
 promises.lua |  6 ++----
 4 files changed, 65 insertions(+), 5 deletions(-)
 create mode 100644 events.lua

diff --git a/README.md b/README.md
index b592877..6d50e5b 100644
--- a/README.md
+++ b/README.md
@@ -1,7 +1,7 @@
 # lua_async
 This project aims to provide an API similar to the Node.js Event loop - for Lua, fully written in Lua itself. It is tested with Lua 5.1 and Lua 5.3.3, but should probably work with any Lua 5.x.
 Note that the goal is not to clone the Node Event loop exactly.
-This is already fully usable, but some features are missing (Events, EventTargets, some Promise methods) and will be implemented in the near future.
+This is already fully usable, but some features are missing (especially some Promise methods) and will be implemented in the near future.
 It also provides a few useful extra methods as well as basic scheduling.
 
 ## Current features
diff --git a/events.lua b/events.lua
new file mode 100644
index 0000000..ee723e8
--- /dev/null
+++ b/events.lua
@@ -0,0 +1,61 @@
+local EventPrototype = {}
+
+function EventPrototype:preventDefault()
+	self.defaultPrevented = true
+end
+
+function Event(type, data)
+	return setmetatable({
+		type = type,
+		data = data,
+		defaultPrevented = false,
+		timeStamp = os.clock(),
+	}, {__index = EventPrototype})
+end
+
+local EventTargetPrototype = {}
+
+function EventTargetPrototype:dispatchEvent(event)
+	event.target = self
+
+	local callback = self["on" + event.type]
+
+	if callback then
+		callback(event)
+	end
+
+	local listeners = self.__eventListeners[type]
+
+	if listeners then
+		for i, callback in ipairs(listeners) do
+			callback(event)
+		end
+	end
+
+	return not event.defaultPrevented
+end
+
+function EventTargetPrototype:addEventListener(type, callback)
+	local listeners = self.__eventListeners[type] or {}
+	table.insert(listeners, callback)
+	self.__eventListeners[type] = listeners
+end
+
+function EventTargetPrototype:removeEventListener(type, callback)
+	local listeners = self.__eventListeners[type]
+
+	if listeners then
+		for k, v in pairs(listeners) do
+			if v == callback then
+				table.remove(listeners, k)
+				break
+			end
+		end
+	end
+end
+
+function EventTarget()
+	return setmetatable({
+		__eventListeners = {},
+	}, {__index = EventTargetPrototype})
+end
diff --git a/init.lua b/init.lua
index 749bee6..07bea3e 100644
--- a/init.lua
+++ b/init.lua
@@ -26,6 +26,7 @@ return function(path)
 		"async_await",
 		"util",
 		"limiting",
+		"events",
 	} do
 		dofile(path .. f .. ".lua")
 	end
diff --git a/promises.lua b/promises.lua
index 0ab61a6..29bcdab 100644
--- a/promises.lua
+++ b/promises.lua
@@ -86,12 +86,10 @@ end
 
 Promise = setmetatable({}, {
 	__call = function(_, resolver)
-		local promise = {
+		local promise = setmetatable({
 			state = "pending",
 			__children = {},
-		}
-
-		setmetatable(promise, {__index = PromisePrototype})
+		}, {__index = PromisePrototype})
 
 		if resolver then
 			resolver(
-- 
2.44.0