private static int SlowGetSegmentPosition(ref SequenceSegment <T> segment, long index)
{
if (index < 0)
{
Throw.IndexOutOfRange();
}
if (segment == null)
{
Throw.ArgumentNull(nameof(segment));
}
do
{
if (index < segment.Length | // inside this segment
(segment.Next == null & index == segment.Length)) // EOF in final segment
{
return((int)index);
}
index -= segment.Length;
segment = segment.Next;
} while (segment != null);
Throw.IndexOutOfRange(); // not in the sequence at all
return(default);
/// <summary>
/// Creates a new SequenceSegment, optionally attaching the segment to an existing chain
/// </summary>
protected SequenceSegment(Memory <T> memory, SequenceSegment <T> previous = null)
{
if (previous != null)
{
var oldNext = previous.Next;
if (oldNext != null)
{
Throw.InvalidOperation("The previous segment already has an onwards chain");
}
previous.Next = this;
RunningIndex = previous.RunningIndex + previous.Length;
}
Memory = memory; // also sets Length
}
internal static int GetSegmentPosition(ref SequenceSegment <T> segment, long index)
=> (index >= 0 & segment != null) && (index < segment.Length)
? (int)index
: SlowGetSegmentPosition(ref segment, index);