// Increments the position reference counts on nodes immediately
// preceding and following a delete operation.
//
// Whenever we delete a span of content, we have to worry about any
// positions still referencing the deleted content. They have enough
// information to find their way back to the surrounding nodes, but
// we need to increment the ref count on those nodes now so that they'll
// still be around when the positions need them.
//
// Because incrementing a ref count on a text node edge may involve
// splitting the text node, this method takes refs to nodes and will
// update the refs if a node is split.
//
// Called by DeleteContentFromSiblingTree and ExtractElementInternal.
private void AdjustRefCountsForContentDelete(ref TextTreeNode previousNode, ElementEdge previousEdge,
ref TextTreeNode nextNode, ElementEdge nextEdge,
TextTreeNode middleSubTree)
{
bool leftEdgeReferenceCount;
bool rightEdgeReferenceCount;
leftEdgeReferenceCount = false;
rightEdgeReferenceCount = false;
// Get the count of all positions referencing text node edges across the deleted content.
GetReferenceCounts((TextTreeNode)middleSubTree.GetMinSibling(), ref leftEdgeReferenceCount, ref rightEdgeReferenceCount);
previousNode = previousNode.IncrementReferenceCount(previousEdge, rightEdgeReferenceCount);
nextNode = nextNode.IncrementReferenceCount(nextEdge, leftEdgeReferenceCount);
}
