/**
* We have a node, for instance DJ x 1. We are interested if it has a superset registered with the
* same support (like CDJ x 1). If yes, then return the vector that contains its superset,
* otherwise return null. We need the vector because the node may have more supersets with the
* same support!
*
* @param node The node whose superset we are looking for in the hash table.
* @return Container of the superset of the node. If the node has no superset registered, return
* null.
*/
public Vector<HashElem> getSupersetContainerOf(ITnode node) {
final int index = node.getHash();
int sizeV, j;
// increase the size of the hash table dynamically
if ((sizeV = this.hashTable.size()) < (index + 1)) {
for (j = 0; j < (index + 1 - sizeV); ++j) {
this.hashTable.add(null);
}
return null;
}
Vector<HashElem> container = this.hashTable.get(index);
if (container == null) {
return null;
}
// else
HashElem elem;
int supp = node.getSupp();
BitSet intent = node.getIntent();
for (Enumeration<HashElem> e = container.elements(); e.hasMoreElements(); ) {
elem = (HashElem) e.nextElement();
if (elem.supp == supp) {
if (SetOp.isProperSubset(intent, elem.intent)) {
return container;
}
}
}
return null;
}
/**
* Tells if the hash table contains the superset (or a subset) of a node. This is the same as the
* function 'containsSupersetOf' just right above, but now we have the option to choose between
* superset or subset lookup.
*
* @param node
* @param supersetOrSubset
* @return
*/
public boolean containsSupersetOrSubsetOf(ITnode node, final int supersetOrSubset) {
final int index = node.getHash();
int sizeV, j;
// increase the size of the hash table dynamically
if ((sizeV = this.hashTable.size()) < (index + 1)) {
for (j = 0; j < (index + 1 - sizeV); ++j) {
this.hashTable.add(null);
}
return false;
}
Vector<HashElem> pos = this.hashTable.get(index);
if (pos == null) {
return false;
}
// else
HashElem elem;
int supp = node.getSupp();
BitSet intent = node.getIntent();
for (Enumeration<HashElem> e = pos.elements(); e.hasMoreElements(); ) {
elem = e.nextElement();
if (elem.supp == supp) {
// looking for a proper superset in the list
if (supersetOrSubset == MyHash.SUPERSET) {
if (SetOp.isProperSubset(intent, elem.intent)) {
return true;
}
} else // if (supersetOrSubset == MyHash.SUBSET), i.e. looking for a proper subset in the
// list
{
if (SetOp.isProperSuperset(intent, elem.intent)) {
return true;
}
}
}
}
return false;
}
/**
* We have a registered elem in the hash. We thought that it was a frequent generator but we
* eventually found a subset of it with the same support. !!! More subsets may be registered !!!
* Thus we delete ALL these supersets and we register the subset.
*
* @param elemContainer The vector that contains the supersets.
* @param node The subset that we want to store instead.
* @return How the number of elements changed (it can be 0 or negative).
*/
public int replace(Vector<HashElem> elemContainer, ITnode node) {
Vector<HashElem> container = this.hashTable.get(node.getHash());
HashElem elem;
int supp = node.getSupp();
BitSet intent = node.getIntent();
Vector<HashElem> toDelete = new Vector<HashElem>();
for (Enumeration<HashElem> e = container.elements(); e.hasMoreElements(); ) {
elem = e.nextElement();
if (elem.supp == supp) {
if (SetOp.isProperSubset(intent, elem.intent)) {
toDelete.add(elem);
}
}
}
container.removeAll(toDelete);
this.add(node);
return (0 - toDelete.size() + 1);
}
