public static IPromise <IPromiseEnumerator <T> > Intersect <T>(IPromiseEnumerator <T> left, IPromiseEnumerator <T> right, IEqualityComparer <T> comparer)
{
return(CountAlgorithm.Count(left).Then(leftCount => CountAlgorithm.Count(right).Then(rightCount =>
{
if (leftCount < rightCount)
{
return Tuple.Create(left, right);
}
return Tuple.Create(right, left);
})).Then(result =>
{
var x = result.Item1;
var y = result.Item2;
return ToSetAlgorithm.ToSet(x, comparer).Then(lookup => WhereEnumerator.Create(y, q => lookup.Contains(q, comparer)));
}));
}
public static IPromise <IPromiseEnumerator <T> > Difference <T>(IPromiseEnumerator <T> left, IPromiseEnumerator <T> right, IEqualityComparer <T> comparer)
{
return(ToSetAlgorithm.ToSet(right, comparer).Then(lookup => WhereEnumerator.Create(left, q => !lookup.Contains(q, comparer))));
}