internal static JsValue PerformPromiseThen(
Engine engine,
PromiseInstance promise,
JsValue onFulfilled,
JsValue onRejected,
PromiseCapability resultCapability)
{
var fulfilReaction = new PromiseReaction(ReactionType.Fulfill, resultCapability, onFulfilled);
var rejectReaction = new PromiseReaction(ReactionType.Reject, resultCapability, onRejected);
switch (promise.State)
{
case PromiseState.Pending:
promise.PromiseFulfillReactions.Add(fulfilReaction);
promise.PromiseRejectReactions.Add(rejectReaction);
break;
case PromiseState.Fulfilled:
engine.AddToEventLoop(NewPromiseReactionJob(fulfilReaction, promise.Value));
break;
case PromiseState.Rejected:
engine.AddToEventLoop(NewPromiseReactionJob(rejectReaction, promise.Value));
break;
default:
ExceptionHelper.ThrowArgumentOutOfRangeException();
break;
}
//https://tc39.es/ecma262/#sec-performpromisethen
//...
//13. If resultCapability is undefined, then
// a. Return undefined
//14. Else
// a. Return resultCapability.[[Promise]]
if (resultCapability is null)
{
return(JsValue.Undefined);
}
return(resultCapability.PromiseInstance);
}
private static Action NewPromiseReactionJob(PromiseReaction reaction, JsValue value)
{
return(() =>
{
var promiseCapability = reaction.Capability;
if (reaction.Handler is ICallable handler)
{
try
{
var result = handler.Call(JsValue.Undefined, new[] { value });
promiseCapability.Resolve.Call(JsValue.Undefined, new[] { result });
}
catch (JavaScriptException e)
{
promiseCapability.Reject.Call(JsValue.Undefined, new[] { e.Error });
}
}
else
{
switch (reaction.Type)
{
case ReactionType.Fulfill:
promiseCapability.Resolve.Call(JsValue.Undefined, new[] { value });
break;
case ReactionType.Reject:
promiseCapability.Reject.Call(JsValue.Undefined, new[] { value });
break;
default:
throw new ArgumentOutOfRangeException();
}
}
});
}