// split this M-tree into a list of trees having height level, which is used in the "splitting" phase of the BulkLoad algorithm
// nCreated is the number of created subtrees,
// level is the split level for the tree,
// children is the list of the parents of each subtree,
// name is the root for the subtrees names
// the return value is the list of splitted subtrees's names
GiSTlist<char *> *
MT::SplitTree (int *nCreated, int level, GiSTlist<MTentry *> *parentEntries, const char *name)
{
GiSTlist<MTnode *> *oldList = new GiSTlist<MTnode *>; // upper level nodes
MTnode *node = new MTnode; // this is because the first operation on node is a delete
GiSTpath path;
path.MakeRoot ();
oldList->Append((MTnode *) ReadNode(path)); // insert the root
do { // build the roots list
GiSTlist<MTnode *> *newList = new GiSTlist<MTnode *>; // lower level nodes
while (!oldList->IsEmpty()) {
delete node; // delete the old node created by ReadNode
node = oldList->RemoveFront(); // retrieve next node to be examined
path = node->Path();
for (int i=0; i<node->NumEntries(); i++) { // append all its children to the new list
path.MakeChild ((*node)[i].Ptr()->Ptr());
newList->Append((MTnode *)ReadNode(path));
path.MakeParent ();
}
}
delete oldList;
oldList = newList;
} while (node->Level() > level); // stop if we're at the split level
delete node;
GiSTlist<char *> *newTreeNames = new GiSTlist<char *>; // this is the results list
while (!oldList->IsEmpty()) { // now append each sub-tree to its root
char newName[50];
sprintf (newName, "%s.%i", name, ++(*nCreated));
unlink (newName); // if this M-tree already exists, delete it
MT *newTree = new MT;
newTree->Create(newName); // create a new M-tree
path.MakeRoot ();
MTnode *rootNode = (MTnode *) newTree->ReadNode(path); // read the root of the new tree
node = oldList->RemoveFront();
newTree->Append(rootNode, (MTnode *)node->Copy()); // append the current node to the root of new tree
parentEntries->Append(node->ParentEntry()); // insert the original parent entry into the list
newTreeNames->Append(strdup(newName)); // insert the new M-tree name into the list
delete node;
delete rootNode;
delete newTree;
}
delete oldList;
return newTreeNames;
}
GiSTentry *
MTnode::Union () const
{
Object *objTemp = NULL;
if (!obj) { // retrieve the node's parent object
MTentry *parentEntry = ParentEntry ();
((MTnode *)this)->obj = (objTemp = new Object(parentEntry->object()));
delete parentEntry;
}
GiSTpath path = ((MTnode *)this)->Path();
MTentry *unionEntry = new MTentry;
unionEntry->InitKey();
if (path.Level() > 1) { // len>=3
MTentry *parentEntry = ParentEntry ();
if (parentEntry) { // copy the entry
unionEntry->Key()->distance = parentEntry->Key()->distance;
if (parentEntry->Key()->splitted) {
unionEntry->Key()->splitted = TRUE;
}
delete parentEntry;
}
if (unionEntry->Key()->distance == -MaxDist()) { // compute the distance from the parent
MTnode *parentNode = ((MT *)Tree())->ParentNode((MTnode *)this);
MTentry *grandEntry = parentNode->ParentEntry();
unionEntry->Key()->distance = obj->distance(grandEntry->object());
unionEntry->Key()->splitted = TRUE;
delete grandEntry;
delete parentNode;
}
}
unionEntry->SetObject(*obj);
unionEntry->SetMaxRadius(0);
unionEntry->SetMinRadius(MAXDOUBLE);
mMRadius (unionEntry); // compute the radii
if (objTemp) {
delete objTemp;
}
((MTnode *)this)->obj = NULL;
return unionEntry;
}
