Port EventEmitter from Node.js

worldeditadditions_core/core/lib/EventEmitter.lua

@@ -0,0 +1,50 @@
+
+--- A 3-dimensional vector.
+-- @class
+local EventEmitter = {}
+EventEmitter.__index = EventEmitter
+EventEmitter.__name = "EventEmitter" -- A hack to allow identification in wea.inspect
+
+
+function EventEmitter.new()
+	local result = {
+		events = {}
+	}
+	setmetatable(result, EventEmitter)
+	return result
+end
+
+function EventEmitter.addEventListener(this, event_name, func)
+	if this.events[event_name] == nil then this.events[event_name] = {} end
+	table.insert(this.events[event_name], func)
+end
+function EventEmitter.on(this, event_name, func)
+	return EventEmitter.addEventListener(this, event_name, func)
+end
+
+function EventEmitter.removeEventListener(this, event_name, func)
+	if this.events[event_name] == nil then return false end
+	for index, next_func in ipairs(this.events[event_name]) do
+		if next_func == func then
+			table.remove(this.events[event_name], index)
+			break
+		end
+	end
+end
+function EventEmitter.off(this, event_name, func)
+	return EventEmitter.removeEventListener(this, event_name, func)
+end
+
+function EventEmitter.emit(this, event_name, args)
+	if this.events[event_name] == nil then return end
+	for index,next_func in ipairs(this.events[event_name]) do
+		next_func(args) -- TODO: Move unpack compat to wea_c
+	end
+	-- TODO: Monitor execution time, log if it's slow? We'll need to move WEA utils over to wea_c first though...
+end
+
+function EventEmitter.clear(this, event_name)
+	this.events[event_name] = nil
+end
+
+return EventEmitter

worldeditadditions_core/init.lua

@@ -27,7 +27,7 @@ wea_c.register_command = dofile(modpath.."/core/register_command.lua")
 wea_c.fetch_command_def = dofile(modpath.."/core/fetch_command_def.lua")
 wea_c.register_alias = dofile(modpath.."/core/register_alias.lua")
 wea_c.pos = dofile(modpath.."/core/pos.lua")
-
+wea_c.EventEmitter = dofile(modpath.."/core/lib/EventEmitter.lua")
 print("WEA_C pos", wea_c.pos.push)
 
 -- Initialise WorldEdit stuff if the WorldEdit mod is not present