/**
* Resolves unwanted text node adjacency which can result from structural changes in the database.
* Adjacent text nodes are two text nodes A and B, where PRE(B)=PRE(A)+1 and PARENT(A)=PARENT(B).
*/
private void resolveTextAdjacency() {
// Text node merges are also gathered on a separate list to leverage optimizations.
final AtomicUpdateList allMerges = new AtomicUpdateList(data);
// keep track of the visited locations to avoid superfluous checks
final IntSet s = new IntSet();
// Text nodes have to be merged from the highest to the lowest pre value
for (int i = 0; i < updStructural.size(); i++) {
final BasicUpdate u = updStructural.get(i);
final Data insseq = u.getInsertionData();
// calculate the new location of the update, here we have to check for adjacency
final int newLocation = u.location + u.accumulatedShifts - u.shifts;
final int beforeNewLocation = newLocation - 1;
// check surroundings of this location for adjacent text nodes depending on the
// kind of update, first the one with higher PRE values (due to shifts!)
// ... for insert/replace ...
if (insseq != null) {
// calculate the current following node
final int followingNode = newLocation + insseq.meta.size;
final int beforeFollowingNode = followingNode - 1;
// check the nodes at the end of/after the insertion sequence
if (!s.contains(beforeFollowingNode)) {
final AtomicUpdateList merges = necessaryMerges(beforeFollowingNode, allMerges.data);
mergeNodes(merges);
allMerges.merge(merges);
s.add(beforeFollowingNode);
}
}
// check nodes for delete and for insert before the updated location
if (!s.contains(beforeNewLocation)) {
final AtomicUpdateList merges = necessaryMerges(beforeNewLocation, allMerges.data);
mergeNodes(merges);
allMerges.merge(merges);
s.add(beforeNewLocation);
}
}
allMerges.updateDistances();
allMerges.clear();
}
/**
* 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));
}
}
}