MoonScript Promise

thread = require("thread")

class Promise
	new: (async) =>
		@result = {}
		@rejectedHandlers = {}
		@fulfilledHandlers = {}
		@state = "pending"
		handlersCache = 0
		@resolve = (a) =>
			@result = a
			handlers = @fulfilledHandlers
			for i = handlersCache+1, #handlers
				handlersCache = i
				if type(@result) == "table" and @result.__class == @@
					result = @result\await()
					if @result.state == "rejected"
						@reject(@result)
						return
					@result = result
				res = {pcall(handlers[i],@result)}
				success = table.remove(res,1)
				@result = res[1]
				if not success
					@reject(@result)
					return
			@state = "fulfilled"
		@reject = (a) =>
			@result = a
			handlers = @rejectedHandlers
			for i = handlersCache+1, #handlers
				handlersCache = i
				res = {pcall(handlers[i],@result)}
				success = table.remove(res,1)
				@result = res[1]
				if success then
					@resolve(@result)
					return
			@state = "rejected"
		@thread = thread.create(() ->
			resolve = (...) ->
				if @state == "pending"
					@resolve(...)
			reject = (...) ->
				if @state == "pending"
					@reject(...)
			success, reason = pcall(async,resolve,reject)
			if not success
				@reject(reason)
		)
	next: (onResolve,onReject) =>
		table.insert(@fulfilledHandlers,onResolve)
		if @state =="fulfilled"
			@resolve(@result)
		if not onReject
			onReject = (e) -> error(e)
		table.insert(@rejectedHandlers,onReject)
		return @
	catch: (onReject) =>
		table.insert(@rejectedHandlers,onReject)
		if @state == "rejected"
			@reject(@result)
		table.insert(@fulfilledHandlers,(a)->return a)
		return @
	await: () =>
		thread.waitForAny({@thread})
		return @result

Promise.all = (list) ->
	return Promise((resolve, reject) ->
		values = {}
		while true
			os.sleep(0.1)
			isFulfilled = true
			for i = 1, #list
				prom = list[i]
				if prom.state == "pending"
					isFulfilled = false
				elseif prom.state == "rejected"
					reject(prom.result)
				elseif prom.state == "fulfilled"
					table.remove(list,i)
					promResult = prom.result
					table.insert(values,promResult)
			if isFulfilled
				resolve(values)
	)

Promise.race = (list) ->
	for i = 1, #list
		if not (type(list[i]) == "table" and list[i].__class and list[i].__class.__name == "Promise")
			list[i] = Promise.resolve(list[i])
	return Promise((resolve,reject) ->
		while true do
			os.sleep(0.1)
			for i = 1, #list
				prom = list[i]
				if prom.state ~= "pending"
					if prom.state == "rejected"
						reject(prom.result)
					elseif prom.state == "fulfilled"
						resolve(prom.result)
)
Promise.resolve = (value) ->
	return Promise((a,b) ->
		a(value)
	)
Promise.reject = (reason) ->
	return Promise((a,b)->
		b(reason)
	)

return Promise