+++ /dev/null
-package org.apache.lucene.search;
-
-/**
- * Copyright 2004 The Apache Software Foundation
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- * http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-import java.io.IOException;
-
-/**
- * The Scorer for DisjunctionMaxQuery. The union of all documents generated by the the subquery scorers
- * is generated in document number order. The score for each document is the maximum of the scores computed
- * by the subquery scorers that generate that document, plus tieBreakerMultiplier times the sum of the scores
- * for the other subqueries that generate the document.
- */
-class DisjunctionMaxScorer extends Scorer {
-
- /* The scorers for subqueries that have remaining docs, kept as a min heap by number of next doc. */
- private final Scorer[] subScorers;
- private int numScorers;
- /* Multiplier applied to non-maximum-scoring subqueries for a document as they are summed into the result. */
- private final float tieBreakerMultiplier;
- private int doc = -1;
-
- /* Used when scoring currently matching doc. */
- private float scoreSum;
- private float scoreMax;
-
- /**
- * Creates a new instance of DisjunctionMaxScorer
- *
- * @param weight
- * The Weight to be used.
- * @param tieBreakerMultiplier
- * Multiplier applied to non-maximum-scoring subqueries for a
- * document as they are summed into the result.
- * @param similarity
- * -- not used since our definition involves neither coord nor terms
- * directly
- * @param subScorers
- * The sub scorers this Scorer should iterate on
- * @param numScorers
- * The actual number of scorers to iterate on. Note that the array's
- * length may be larger than the actual number of scorers.
- */
- public DisjunctionMaxScorer(Weight weight, float tieBreakerMultiplier,
- Similarity similarity, Scorer[] subScorers, int numScorers) throws IOException {
- super(similarity, weight);
- this.tieBreakerMultiplier = tieBreakerMultiplier;
- // The passed subScorers array includes only scorers which have documents
- // (DisjunctionMaxQuery takes care of that), and their nextDoc() was already
- // called.
- this.subScorers = subScorers;
- this.numScorers = numScorers;
-
- heapify();
- }
-
- @Override
- public int nextDoc() throws IOException {
- if (numScorers == 0) return doc = NO_MORE_DOCS;
- while (subScorers[0].docID() == doc) {
- if (subScorers[0].nextDoc() != NO_MORE_DOCS) {
- heapAdjust(0);
- } else {
- heapRemoveRoot();
- if (numScorers == 0) {
- return doc = NO_MORE_DOCS;
- }
- }
- }
-
- return doc = subScorers[0].docID();
- }
-
- @Override
- public int docID() {
- return doc;
- }
-
- /** Determine the current document score. Initially invalid, until {@link #nextDoc()} is called the first time.
- * @return the score of the current generated document
- */
- @Override
- public float score() throws IOException {
- int doc = subScorers[0].docID();
- scoreSum = scoreMax = subScorers[0].score();
- int size = numScorers;
- scoreAll(1, size, doc);
- scoreAll(2, size, doc);
- return scoreMax + (scoreSum - scoreMax) * tieBreakerMultiplier;
- }
-
- // Recursively iterate all subScorers that generated last doc computing sum and max
- private void scoreAll(int root, int size, int doc) throws IOException {
- if (root < size && subScorers[root].docID() == doc) {
- float sub = subScorers[root].score();
- scoreSum += sub;
- scoreMax = Math.max(scoreMax, sub);
- scoreAll((root<<1)+1, size, doc);
- scoreAll((root<<1)+2, size, doc);
- }
- }
-
- @Override
- public int advance(int target) throws IOException {
- if (numScorers == 0) return doc = NO_MORE_DOCS;
- while (subScorers[0].docID() < target) {
- if (subScorers[0].advance(target) != NO_MORE_DOCS) {
- heapAdjust(0);
- } else {
- heapRemoveRoot();
- if (numScorers == 0) {
- return doc = NO_MORE_DOCS;
- }
- }
- }
- return doc = subScorers[0].docID();
- }
-
- // Organize subScorers into a min heap with scorers generating the earliest document on top.
- private void heapify() {
- for (int i = (numScorers >> 1) - 1; i >= 0; i--) {
- heapAdjust(i);
- }
- }
-
- /* The subtree of subScorers at root is a min heap except possibly for its root element.
- * Bubble the root down as required to make the subtree a heap.
- */
- private void heapAdjust(int root) {
- Scorer scorer = subScorers[root];
- int doc = scorer.docID();
- int i = root;
- while (i <= (numScorers >> 1) - 1) {
- int lchild = (i << 1) + 1;
- Scorer lscorer = subScorers[lchild];
- int ldoc = lscorer.docID();
- int rdoc = Integer.MAX_VALUE, rchild = (i << 1) + 2;
- Scorer rscorer = null;
- if (rchild < numScorers) {
- rscorer = subScorers[rchild];
- rdoc = rscorer.docID();
- }
- if (ldoc < doc) {
- if (rdoc < ldoc) {
- subScorers[i] = rscorer;
- subScorers[rchild] = scorer;
- i = rchild;
- } else {
- subScorers[i] = lscorer;
- subScorers[lchild] = scorer;
- i = lchild;
- }
- } else if (rdoc < doc) {
- subScorers[i] = rscorer;
- subScorers[rchild] = scorer;
- i = rchild;
- } else {
- return;
- }
- }
- }
-
- // Remove the root Scorer from subScorers and re-establish it as a heap
- private void heapRemoveRoot() {
- if (numScorers == 1) {
- subScorers[0] = null;
- numScorers = 0;
- } else {
- subScorers[0] = subScorers[numScorers - 1];
- subScorers[numScorers - 1] = null;
- --numScorers;
- heapAdjust(0);
- }
- }
-
-}