/// <summary> Finds a series of nodes that are affected by a change at the given index. </summary>
/// <param name="range"> The range at which a change is being applied </param>
/// <returns> The nodes that are affected by the change. </returns>
private FoundNode GetAffectedNodes(Range range)
{
var listNode = _subFragments.First;
int absoluteIndexOfLastSubFragment = 0;
var foundNode = new FoundNode();
while (listNode != null)
{
MarkupNodeReference subFragment = listNode.Value;
var subFragmentAbsoluteStart = absoluteIndexOfLastSubFragment + subFragment.RelativeOffsetSinceLastNode;
var nodeRange = new Range(subFragmentAbsoluteStart, subFragmentAbsoluteStart + subFragment.Length);
if (range.EndIndex < nodeRange.StartIndex)
{
// the change is before every remaining sub-fragment, so we can bail out now
foundNode.MarkRemaining(listNode);
break;
}
if (nodeRange.OverlapsInclusive(range))
{
foundNode.RememberFirstAndLast(nodeRange.StartIndex, listNode);
}
absoluteIndexOfLastSubFragment = nodeRange.StartIndex;
listNode = listNode.Next;
}
return(foundNode);
}
/// <summary> Transforms a single range using the given modification. </summary>
private Range Transform(Range range, RangeModification modification)
{
if (modification.WasAdded)
{
if (range.ContainsExclusive(modification.Index))
{
return(new Range(range.StartIndex, range.EndIndex + modification.NumberOfItems));
}
else if (range.StartIndex < modification.Index)
{
return(range);
}
else
{
return(new Range(range.StartIndex + modification.NumberOfItems,
range.EndIndex + modification.NumberOfItems));
}
}
else
{
var deletionRange = new Range(modification.Index, modification.Index + modification.NumberOfItems);
if (deletionRange.ContainsInclusive(range.StartIndex) && deletionRange.ContainsInclusive(range.EndIndex))
{
// if the deletion range took out the range, remove it altogether
return(new Range(deletionRange.StartIndex, deletionRange.StartIndex));
}
else if (deletionRange.OverlapsInclusive(range))
{
if (deletionRange.StartIndex <= range.StartIndex)
{
int overlappingCharCount = deletionRange.EndIndex - range.StartIndex;
int numberOfCharactersBefore = range.StartIndex - deletionRange.StartIndex;
int numberOfAvailableCharsToDelete = Math.Min(overlappingCharCount,
range.Length);
return(new Range(range.StartIndex - numberOfCharactersBefore,
range.EndIndex - numberOfCharactersBefore - numberOfAvailableCharsToDelete));
}
else /* range.StartIndex <= deletionRange.EndIndex */
{
var numberOfCharsToDelete = Math.Min(range.EndIndex - deletionRange.StartIndex, deletionRange.Length);
return(new Range(range.StartIndex, range.EndIndex - numberOfCharsToDelete));
}
}
else if (deletionRange.StartIndex < range.StartIndex)
{
return(new Range(range.StartIndex - modification.NumberOfItems,
range.EndIndex - modification.NumberOfItems));
}
else
{
return(range);
}
}
}
