rusty-luau/lib/future.luau

99 lines
2.3 KiB
Lua

local task = require("@lune/task")
local mod = require("../mod")
local Signal = mod.signal
type Signal<T...> = mod.Signal<T...>
local result = require("result")
export type Result<T, E> = result.Result<T, E>
local Ok = result.Ok
local Err = result.Err
local Future = {}
export type Status = "initialized" | "running" | "cancelled" | "done"
export type Future<T> = typeof(Future) & {
_fn: (set: (value: T) -> ()) -> T,
_ret: T,
_thread: thread,
_spawnEvt: Signal<()>,
_retEvt: Signal<T | Result<T, string>, Status>,
_status: Status,
}
local function _constructor<T>(fn: (Signal<()>, Signal<T, Status>) -> (), args: { any })
return setmetatable(
{
_thread = coroutine.create(fn),
_spawnEvt = Signal.new(),
_retEvt = Signal.new(),
_status = "initialized",
} :: Future<T>,
{
__index = Future,
}
)
end
function Future.new<T>(fn: (...any) -> T, args: { any })
return _constructor(function(spawnEvt: Signal<()>, retEvt: Signal<T, Status>)
spawnEvt:Fire()
local ret = fn(table.unpack(args))
retEvt:Fire(ret, "done")
end, args)
end
function Future.try<T>(fn: (...any) -> T, args: { any })
return _constructor(function(spawnEvt: Signal<()>, retEvt: Signal<Result<T, string>, Status>)
spawnEvt:Fire()
local ok, ret = pcall(fn, table.unpack(args))
local result: Result<T, string> = if ok then Ok(ret) else Err(ret)
retEvt:Fire(result, "done")
end, args)
end
function Future.poll<T>(self: Future<T>): (Status, T)
if self._status == "initialized" then
self._retEvt:Connect(function(firedRet, status: Status)
self._status = status
self._ret = firedRet
-- Cleanup
coroutine.yield(self._thread)
coroutine.close(self._thread)
self._spawnEvt:DisconnectAll()
self._retEvt:DisconnectAll()
end)
self._spawnEvt:Connect(function()
self._status = "running"
end)
coroutine.resume(self._thread, self._spawnEvt, self._retEvt)
end
if self._status == "running" then
-- Just wait a bit more for the signal to fire
task.wait(0.01)
end
return self._status, self._ret
end
function Future.cancel<T>(self: Future<T>)
self._retEvt:Fire(nil :: any, "cancelled")
self._status = "cancelled"
end
function Future.await<T>(self: Future<T>): T
while true do
local status: Status, ret: T = self:poll()
if status == "done" then
return ret
end
end
end