/// <summary>
/// Chain a sequence of operations using promises.
/// Takes a collection of functions each of which starts an async operation and yields a promise.
/// </summary>
public static IFpromise Sequence(IEnumerable <Func <IFpromise> > fns)
{
return(fns.Aggregate(
Fpromise.Resolved(),
(prevFpromise, fn) =>
{
return prevFpromise.Then(() => fn());
}
));
}
/// <summary>
/// Returns a promise that resolves when all of the promises in the enumerable argument have resolved.
/// Returns a promise of a collection of the resolved results.
/// </summary>
public static IFpromise <IEnumerable <FpromisedT> > All(IEnumerable <IFpromise <FpromisedT> > promises)
{
var promisesArray = promises.ToArray();
if (promisesArray.Length == 0)
{
return(Fpromise <IEnumerable <FpromisedT> > .Resolved(EnumerableExtensions.Empty <FpromisedT>()));
}
var remainingCount = promisesArray.Length;
var results = new FpromisedT[remainingCount];
var resultFpromise = new Fpromise <IEnumerable <FpromisedT> >();
resultFpromise.WithName("All");
promisesArray.Each((promise, index) =>
{
promise
.Catch(ex =>
{
if (resultFpromise.CurState == FpromiseState.Pending)
{
// If a promise errorred and the result promise is still pending, reject it.
resultFpromise.Reject(ex);
}
})
.Then(result =>
{
results[index] = result;
--remainingCount;
if (remainingCount <= 0)
{
// This will never happen if any of the promises errorred.
resultFpromise.Resolve(results);
}
})
.Done();
});
return(resultFpromise);
}