/**
* Simple algorithm that computes the OR aggregate.
*
* @param bitmaps input bitmaps
* @return new bitmap containing the aggregate
*/
public static EWAHCompressedBitmap32 or(final EWAHCompressedBitmap32... bitmaps) {
PriorityQueue<EWAHCompressedBitmap32> pq =
new PriorityQueue<EWAHCompressedBitmap32>(
bitmaps.length,
new Comparator<EWAHCompressedBitmap32>() {
@Override
public int compare(EWAHCompressedBitmap32 a, EWAHCompressedBitmap32 b) {
return a.sizeInBytes() - b.sizeInBytes();
}
});
Collections.addAll(pq, bitmaps);
if (pq.isEmpty()) return new EWAHCompressedBitmap32();
while (pq.size() > 1) {
EWAHCompressedBitmap32 x1 = pq.poll();
EWAHCompressedBitmap32 x2 = pq.poll();
pq.add(x1.or(x2));
}
return pq.poll();
}
/**
* Simple algorithm that computes the OR aggregate.
*
* @param bitmaps input bitmaps
* @return new bitmap containing the aggregate
*/
public static EWAHCompressedBitmap32 or(final Iterator<EWAHCompressedBitmap32> bitmaps) {
PriorityQueue<EWAHCompressedBitmap32> pq =
new PriorityQueue<EWAHCompressedBitmap32>(
32,
new Comparator<EWAHCompressedBitmap32>() {
@Override
public int compare(EWAHCompressedBitmap32 a, EWAHCompressedBitmap32 b) {
return a.sizeInBytes() - b.sizeInBytes();
}
});
while (bitmaps.hasNext()) pq.add(bitmaps.next());
if (pq.isEmpty()) return new EWAHCompressedBitmap32();
while (pq.size() > 1) {
EWAHCompressedBitmap32 x1 = pq.poll();
EWAHCompressedBitmap32 x2 = pq.poll();
pq.add(x1.or(x2));
}
return pq.poll();
}
/**
* Uses a priority queue to compute the or aggregate.
*
* <p>The content of the container is overwritten.
*
* <p>This algorithm runs in linearithmic time (O(n log n)) with respect to the number of bitmaps.
*
* @param container where we write the result
* @param bitmaps to be aggregated
*/
public static void orToContainer(
final BitmapStorage32 container, final EWAHCompressedBitmap32... bitmaps) {
if (bitmaps.length < 2) throw new IllegalArgumentException("We need at least two bitmaps");
PriorityQueue<EWAHCompressedBitmap32> pq =
new PriorityQueue<EWAHCompressedBitmap32>(
bitmaps.length,
new Comparator<EWAHCompressedBitmap32>() {
@Override
public int compare(EWAHCompressedBitmap32 a, EWAHCompressedBitmap32 b) {
return a.sizeInBytes() - b.sizeInBytes();
}
});
Collections.addAll(pq, bitmaps);
while (pq.size() > 2) {
EWAHCompressedBitmap32 x1 = pq.poll();
EWAHCompressedBitmap32 x2 = pq.poll();
pq.add(x1.or(x2));
}
pq.poll().orToContainer(pq.poll(), container);
}
