/**
* Calculates the new distance value for the given node.
*
* @param preAfter the current PRE value of the node (after structural updates have been applied)
* @return new distance for the given node
*/
private int calculateNewDistance(final int preAfter) {
final int kind = data.kind(preAfter);
final int distanceBefore = data.dist(preAfter, kind);
final int preBefore = calculatePreValue(preAfter, true);
final int parentBefore = preBefore - distanceBefore;
final int parentAfter = calculatePreValue(parentBefore, false);
return preAfter - parentAfter;
}
/**
* This method updates the distance values of the specified pre value and the following siblings
* of all ancestor-or-self nodes.
*
* @param pre root node
* @param size size to be added/removed
*/
private void updateDist(final int pre, final int size) {
int p = pre;
while (p < meta.size) {
final int k = kind(p);
if (k == DOC) break;
dist(p, k, dist(p, k) + size);
p += size(p, k);
}
}
/**
* Updates distances to restore parent-child relationships that have been invalidated by
* structural updates.
*
* <p>Each structural update (insert/delete) leads to a shift of higher PRE values. This
* invalidates parent-child relationships. Distances are only updated after all structural updates
* have been carried out to make sure each node (that has to be updated) is only touched once.
*/
public void updateDistances() {
accumulatePreValueShifts();
final IntSet alreadyUpdatedNodes = new IntSet();
for (final BasicUpdate update : updStructural) {
int newPreOfAffectedNode = update.preOfAffectedNode + update.accumulatedShifts;
/* Update distance for the affected node and all following siblings of nodes
* on the ancestor-or-self axis. */
while (newPreOfAffectedNode < data.meta.size) {
if (alreadyUpdatedNodes.contains(newPreOfAffectedNode)) break;
data.dist(
newPreOfAffectedNode,
data.kind(newPreOfAffectedNode),
calculateNewDistance(newPreOfAffectedNode));
alreadyUpdatedNodes.add(newPreOfAffectedNode);
newPreOfAffectedNode += data.size(newPreOfAffectedNode, data.kind(newPreOfAffectedNode));
}
}
}
