void RemoveInternal(ref DeferredEventList deferredEventList, int offset, int length)
{
Debug.Assert(length >= 0);
if (length == 0)
{
return;
}
LineSegmentTree.Enumerator it = lineCollection.GetEnumeratorForOffset(offset);
LineSegment startSegment = it.Current;
int startSegmentOffset = startSegment.Offset;
if (offset + length < startSegmentOffset + startSegment.TotalLength)
{
// just removing a part of this line segment
startSegment.RemovedLinePart(ref deferredEventList, offset - startSegmentOffset, length);
SetSegmentLength(startSegment, startSegment.TotalLength - length);
return;
}
// merge startSegment with another line segment because startSegment's delimiter was deleted
// possibly remove lines in between if multiple delimiters were deleted
int charactersRemovedInStartLine = startSegmentOffset + startSegment.TotalLength - offset;
Debug.Assert(charactersRemovedInStartLine > 0);
startSegment.RemovedLinePart(ref deferredEventList, offset - startSegmentOffset, charactersRemovedInStartLine);
LineSegment endSegment = lineCollection.GetByOffset(offset + length);
if (endSegment == startSegment)
{
// special case: we are removing a part of the last line up to the
// end of the document
SetSegmentLength(startSegment, startSegment.TotalLength - length);
return;
}
int endSegmentOffset = endSegment.Offset;
int charactersLeftInEndLine = endSegmentOffset + endSegment.TotalLength - (offset + length);
endSegment.RemovedLinePart(ref deferredEventList, 0, endSegment.TotalLength - charactersLeftInEndLine);
startSegment.MergedWith(endSegment, offset - startSegmentOffset);
SetSegmentLength(startSegment, startSegment.TotalLength - charactersRemovedInStartLine + charactersLeftInEndLine);
startSegment.DelimiterLength = endSegment.DelimiterLength;
// remove all segments between startSegment (excl.) and endSegment (incl.)
it.MoveNext();
LineSegment segmentToRemove;
do
{
segmentToRemove = it.Current;
it.MoveNext();
lineCollection.RemoveSegment(segmentToRemove);
segmentToRemove.Deleted(ref deferredEventList);
} while (segmentToRemove != endSegment);
}