Async for fun

Async.cs

static IEnumerable<Task> DoItAsync()
{
    yield return Task.Delay(1000);
    yield return Task.Run(() => 1 + 1);

    Console.WriteLine("hello");
}

public static Task AsyncEnumerator(Func<IEnumerable<Task>> taskChainFactory)
{
    var tcs = new TaskCompletionSource<object>();

    var enumerator = taskChainFactory().GetEnumerator();

    AsyncEnumeratorImpl(tcs, enumerator);

    return tcs.Task;
}

private static void AsyncEnumeratorImpl(TaskCompletionSource<object> tcs, IEnumerator<Task> enumerator)
{
    while (enumerator.MoveNext())
    {
        Task task = enumerator.Current;
        if (task.IsCompleted)
        {
            try
            {
                task.Wait();
            }
            catch(Exception ex)
            {
                tcs.TrySetException(ex);
            }
        }
        else
        {
            ContinueAsync(tcs, enumerator, task);

            return;
        }
    }

    tcs.TrySetResult(null);
}

private static void ContinueAsync(TaskCompletionSource<object> tcs, IEnumerator<Task> enumerator, Task task)
{
    task.ContinueWith(t =>
    {
        if (t.IsFaulted)
        {
            tcs.TrySetException(t.Exception);
        }
        else if (t.IsCanceled)
        {
            tcs.TrySetCanceled();
        }
        else
        {
            AsyncEnumeratorImpl(tcs, enumerator);
        }
    });
}
}