public static IPromise <IPromiseEnumerator <T> > DefaultIfEmpty <T>(IPromiseEnumerator <T> items, T defaultValue)
{
return(items.MoveNext().Then(result =>
{
if (result == null)
{
return PromiseEnumerator.Create(items.Factory, new T[] { defaultValue });
}
return items.Factory.Value(items);
}));
}
public static IPromise <IPromiseEnumerator <T> > Reverse <T>(IPromiseEnumerator <T> items)
{
return(items.MoveNext().Then(result =>
{
if (result == null)
{
return null;
}
return PromiseEnumerator.Create(items.Factory, new T[] { result.Current }).Then(right =>
{
return Reverse(result).Then(left =>
{
return (IPromiseEnumerator <T>)(ConcatEnumerator.Create(left, right));
});
});
}));
}
