Created
September 1, 2021 22:56
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Heap based disjunction of multiple DocIdSetIterator instances
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| import org.apache.lucene.search.DocIdSetIterator; | |
| import org.apache.lucene.util.BitSetIterator; | |
| import org.apache.lucene.util.FixedBitSet; | |
| import org.apache.lucene.util.RoaringDocIdSet; | |
| import java.io.IOException; | |
| public class SimpleDisjunctionDISI extends DocIdSetIterator | |
| { | |
| private final DISIWrapper[] heap; | |
| private final long cost; | |
| private int size; | |
| public SimpleDisjunctionDISI (DocIdSetIterator... iterators) | |
| { | |
| heap = new DISIWrapper[iterators.length]; | |
| size = 0; | |
| for (DocIdSetIterator it : iterators) | |
| { | |
| add (new DISIWrapper (it)); | |
| } | |
| long cost = 0; | |
| for (DISIWrapper wrapper : heap) | |
| { | |
| cost += wrapper.cost; | |
| } | |
| this.cost = cost; | |
| } | |
| private static int leftNode (int node) | |
| { | |
| return ((node + 1) << 1) - 1; | |
| } | |
| private static int rightNode (int leftNode) | |
| { | |
| return leftNode + 1; | |
| } | |
| private static int parentNode (int node) | |
| { | |
| return ((node + 1) >>> 1) - 1; | |
| } | |
| private DISIWrapper top () | |
| { | |
| return heap[0]; | |
| } | |
| public int size () | |
| { | |
| return size; | |
| } | |
| private DISIWrapper add (DISIWrapper entry) | |
| { | |
| final DISIWrapper[] heap = this.heap; | |
| final int size = this.size; | |
| heap[size] = entry; | |
| upHeap (size); | |
| this.size = size + 1; | |
| return heap[0]; | |
| } | |
| private void upHeap (int i) | |
| { | |
| final DISIWrapper node = heap[i]; | |
| final int nodeDoc = node.doc; | |
| int j = parentNode (i); | |
| while (j >= 0 && nodeDoc < heap[j].doc) | |
| { | |
| heap[i] = heap[j]; | |
| i = j; | |
| j = parentNode (j); | |
| } | |
| heap[i] = node; | |
| } | |
| private DISIWrapper updateTop () | |
| { | |
| downHeap (size); | |
| return heap[0]; | |
| } | |
| private void downHeap (int size) | |
| { | |
| int i = 0; | |
| final DISIWrapper node = heap[0]; | |
| int j = leftNode (i); | |
| if (j < size) | |
| { | |
| int k = rightNode (j); | |
| if (k < size && heap[k].doc < heap[j].doc) | |
| { | |
| j = k; | |
| } | |
| if (heap[j].doc < node.doc) | |
| { | |
| do | |
| { | |
| heap[i] = heap[j]; | |
| i = j; | |
| j = leftNode (i); | |
| k = rightNode (j); | |
| if (k < size && heap[k].doc < heap[j].doc) | |
| { | |
| j = k; | |
| } | |
| } | |
| while (j < size && heap[j].doc < node.doc); | |
| heap[i] = node; | |
| } | |
| } | |
| } | |
| @Override | |
| public int docID () | |
| { | |
| return top ().doc; | |
| } | |
| @Override | |
| public int nextDoc () throws IOException | |
| { | |
| DISIWrapper top = top (); | |
| final int doc = top.doc; | |
| do | |
| { | |
| top.doc = top.iterator.nextDoc (); | |
| top = updateTop (); | |
| } | |
| while (top.doc == doc); | |
| return top.doc; | |
| } | |
| @Override | |
| public int advance (int target) throws IOException | |
| { | |
| DISIWrapper top = top (); | |
| do | |
| { | |
| top.doc = top.iterator.advance (target); | |
| top = updateTop (); | |
| } | |
| while (top.doc < target); | |
| return top.doc; | |
| } | |
| @Override | |
| public long cost () | |
| { | |
| return cost; | |
| } | |
| private static class DISIWrapper | |
| { | |
| private final DocIdSetIterator iterator; | |
| private final long cost; | |
| private int doc = -1; | |
| private DISIWrapper (DocIdSetIterator iterator) | |
| { | |
| this.iterator = iterator; | |
| this.cost = iterator.cost (); | |
| } | |
| } | |
| public static void main (String[] args) throws IOException | |
| { | |
| FixedBitSet bs = new FixedBitSet (10); | |
| bs.set (8); | |
| bs.set (3); | |
| bs.set (10); | |
| RoaringDocIdSet.Builder b = new RoaringDocIdSet.Builder (100); | |
| b.add (0); | |
| b.add (2); | |
| b.add (10); | |
| b.add (20); | |
| RoaringDocIdSet bs2 = b.build (); | |
| SimpleDisjunctionDISI it = new SimpleDisjunctionDISI (bs2.iterator (), new BitSetIterator (bs, bs.cardinality ())); | |
| int docId; | |
| while ((docId = it.nextDoc ()) != DocIdSetIterator.NO_MORE_DOCS) | |
| { | |
| System.out.println (docId); | |
| } | |
| } | |
| } |
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