public TResult[] ToArray()
{
var builder = new SparseArrayBuilder <TResult>(initialize: true);
ArrayBuilder <IEnumerable <TResult> > deferredCopies = default;
foreach (TSource element in _source)
{
IEnumerable <TResult> enumerable = _selector(element);
if (builder.ReserveOrAdd(enumerable))
{
deferredCopies.Add(enumerable);
}
}
TResult[] array = builder.ToArray();
ArrayBuilder <Marker> markers = builder.Markers;
for (int i = 0; i < markers.Count; i++)
{
Marker marker = markers[i];
IEnumerable <TResult> enumerable = deferredCopies[i];
EnumerableHelpers.Copy(enumerable, array, marker.Index, marker.Count);
}
return(array);
}
public override TSource[] ToArray()
{
var builder = new SparseArrayBuilder <TSource>(initialize: true);
bool reservedFirst = builder.ReserveOrAdd(_first);
bool reservedSecond = builder.ReserveOrAdd(_second);
TSource[] array = builder.ToArray();
if (reservedFirst)
{
Marker marker = builder.Markers.First();
Debug.Assert(marker.Index == 0);
EnumerableHelpers.Copy(_first, array, 0, marker.Count);
}
if (reservedSecond)
{
Marker marker = builder.Markers.Last();
EnumerableHelpers.Copy(_second, array, marker.Index, marker.Count);
}
return(array);
}
private TSource[] LazyToArray()
{
Debug.Assert(!_hasOnlyCollections);
var builder = new SparseArrayBuilder <TSource>(initialize: true);
ArrayBuilder <int> deferredCopies = default;
for (int i = 0; ; i++)
{
// Unfortunately, we can't escape re-walking the linked list for each source, which has
// quadratic behavior, because we need to add the sources in order.
// On the bright side, the bottleneck will usually be iterating, buffering, and copying
// each of the enumerables, so this shouldn't be a noticeable perf hit for most scenarios.
IEnumerable <TSource>?source = GetEnumerable(i);
if (source == null)
{
break;
}
if (builder.ReserveOrAdd(source))
{
deferredCopies.Add(i);
}
}
TSource[] array = builder.ToArray();
ArrayBuilder <Marker> markers = builder.Markers;
for (int i = 0; i < markers.Count; i++)
{
Marker marker = markers[i];
IEnumerable <TSource> source = GetEnumerable(deferredCopies[i]) !;
EnumerableHelpers.Copy(source, array, marker.Index, marker.Count);
}
return(array);
}