private void BoundsCheck(SequencePosition start, SequencePosition newCursor)
{
var startIndex = start.Index;
var endIndex = newCursor.Index;
var type = GetBufferType();
startIndex = GetIndex(startIndex);
endIndex = GetIndex(endIndex);
switch (type)
{
case BufferType.OwnedMemory:
case BufferType.Array:
if (endIndex > startIndex)
{
ThrowHelper.ThrowCursorOutOfBoundsException();
}
return;
case BufferType.MemoryList:
var segment = (IMemoryList <T>)newCursor.Segment;
var memoryList = (IMemoryList <T>)start.Segment;
if (segment.RunningIndex - startIndex > memoryList.RunningIndex - endIndex)
{
ThrowHelper.ThrowCursorOutOfBoundsException();
}
return;
default:
ThrowHelper.ThrowCursorOutOfBoundsException();
return;
}
}
internal SequencePosition Seek(SequencePosition start, SequencePosition end, long bytes, bool checkEndReachable = true)
{
var startIndex = start.Index;
var endIndex = end.Index;
var type = GetBufferType();
startIndex = GetIndex(startIndex);
endIndex = GetIndex(endIndex);
switch (type)
{
case BufferType.MemoryList:
if (start.Segment == end.Segment && endIndex - startIndex >= bytes)
{
// end.Index >= bytes + Index and end.Index is int
return(new SequencePosition(start.Segment, startIndex + (int)bytes));
}
return(SeekMultiSegment((IMemoryList <byte>)start.Segment, startIndex, (IMemoryList <byte>)end.Segment, endIndex, bytes, checkEndReachable));
case BufferType.OwnedMemory:
case BufferType.Array:
if (endIndex - startIndex >= bytes)
{
// end.Index >= bytes + Index and end.Index is int
return(new SequencePosition(start.Segment, startIndex + (int)bytes));
}
ThrowHelper.ThrowCursorOutOfBoundsException();
return(default);
}
ThrowHelper.ThrowInvalidOperationException(ExceptionResource.EndCursorNotReached);
return(default);
private static SequencePosition SeekMultiSegment(IMemoryList <byte> start, int startIndex, IMemoryList <byte> end, int endPosition, long bytes, bool checkEndReachable)
{
SequencePosition result = default(SequencePosition);
var foundResult = false;
var current = start;
var currentIndex = startIndex;
while (current != null)
{
// We need to loop up until the end to make sure start and end are connected
// if end is not trusted
if (!foundResult)
{
var memory = current.Memory;
var currentEnd = current == end ? endPosition : memory.Length;
memory = memory.Slice(0, currentEnd - currentIndex);
// We would prefer to put cursor in the beginning of next segment
// then past the end of previous one, but only if we are not leaving current buffer
if (memory.Length > bytes ||
(memory.Length == bytes && current == end))
{
result = new SequencePosition(current, currentIndex + (int)bytes);
foundResult = true;
if (!checkEndReachable)
{
break;
}
}
bytes -= memory.Length;
}
if (current.Next == null && current != end)
{
ThrowHelper.ThrowInvalidOperationException(ExceptionResource.EndCursorNotReached);
}
current = current.Next;
currentIndex = 0;
}
if (!foundResult)
{
ThrowHelper.ThrowCursorOutOfBoundsException();
}
return(result);
}
private static Position SeekMultiSegment(Position begin, Position end, long bytes, bool checkEndReachable)
{
Position result = default;
var foundResult = false;
var current = begin;
while (TryGetBuffer(begin, end, out var memory, out begin))
{
// We need to loop up until the end to make sure start and end are connected
// if end is not trusted
if (!foundResult)
{
// We would prefer to put cursor in the beginning of next segment
// then past the end of previous one, but only if next exists
if (memory.Length > bytes ||
(memory.Length == bytes && begin.Segment == null))
{
result = new Position(current.Segment, current.Index + (int)bytes);
foundResult = true;
if (!checkEndReachable)
{
break;
}
}
bytes -= memory.Length;
}
current = begin;
}
if (!foundResult)
{
ThrowHelper.ThrowCursorOutOfBoundsException();
}
return(result);
}
