--- /dev/null
+package org.apache.lucene.search;
+
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You 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.util.List;
+import java.io.IOException;
+
+import org.apache.lucene.util.ScorerDocQueue;
+
+/** A Scorer for OR like queries, counterpart of <code>ConjunctionScorer</code>.
+ * This Scorer implements {@link Scorer#skipTo(int)} and uses skipTo() on the given Scorers.
+ */
+class DisjunctionSumScorer extends Scorer {
+ /** The number of subscorers. */
+ private final int nrScorers;
+
+ /** The subscorers. */
+ protected final List<Scorer> subScorers;
+
+ /** The minimum number of scorers that should match. */
+ private final int minimumNrMatchers;
+
+ /** The scorerDocQueue contains all subscorers ordered by their current doc(),
+ * with the minimum at the top.
+ * <br>The scorerDocQueue is initialized the first time next() or skipTo() is called.
+ * <br>An exhausted scorer is immediately removed from the scorerDocQueue.
+ * <br>If less than the minimumNrMatchers scorers
+ * remain in the scorerDocQueue next() and skipTo() return false.
+ * <p>
+ * After each to call to next() or skipTo()
+ * <code>currentSumScore</code> is the total score of the current matching doc,
+ * <code>nrMatchers</code> is the number of matching scorers,
+ * and all scorers are after the matching doc, or are exhausted.
+ */
+ private ScorerDocQueue scorerDocQueue;
+
+ /** The document number of the current match. */
+ private int currentDoc = -1;
+
+ /** The number of subscorers that provide the current match. */
+ protected int nrMatchers = -1;
+
+ private double currentScore = Float.NaN;
+
+ /** Construct a <code>DisjunctionScorer</code>.
+ * @param weight The weight to be used.
+ * @param subScorers A collection of at least two subscorers.
+ * @param minimumNrMatchers The positive minimum number of subscorers that should
+ * match to match this query.
+ * <br>When <code>minimumNrMatchers</code> is bigger than
+ * the number of <code>subScorers</code>,
+ * no matches will be produced.
+ * <br>When minimumNrMatchers equals the number of subScorers,
+ * it more efficient to use <code>ConjunctionScorer</code>.
+ */
+ public DisjunctionSumScorer(Weight weight, List<Scorer> subScorers, int minimumNrMatchers) throws IOException {
+ super(weight);
+
+ nrScorers = subScorers.size();
+
+ if (minimumNrMatchers <= 0) {
+ throw new IllegalArgumentException("Minimum nr of matchers must be positive");
+ }
+ if (nrScorers <= 1) {
+ throw new IllegalArgumentException("There must be at least 2 subScorers");
+ }
+
+ this.minimumNrMatchers = minimumNrMatchers;
+ this.subScorers = subScorers;
+
+ initScorerDocQueue();
+ }
+
+ /** Construct a <code>DisjunctionScorer</code>, using one as the minimum number
+ * of matching subscorers.
+ */
+ public DisjunctionSumScorer(Weight weight, List<Scorer> subScorers) throws IOException {
+ this(weight, subScorers, 1);
+ }
+
+ /** Called the first time next() or skipTo() is called to
+ * initialize <code>scorerDocQueue</code>.
+ */
+ private void initScorerDocQueue() throws IOException {
+ scorerDocQueue = new ScorerDocQueue(nrScorers);
+ for (Scorer se : subScorers) {
+ if (se.nextDoc() != NO_MORE_DOCS) {
+ scorerDocQueue.insert(se);
+ }
+ }
+ }
+
+ /** Scores and collects all matching documents.
+ * @param collector The collector to which all matching documents are passed through.
+ */
+ @Override
+ public void score(Collector collector) throws IOException {
+ collector.setScorer(this);
+ while (nextDoc() != NO_MORE_DOCS) {
+ collector.collect(currentDoc);
+ }
+ }
+
+ /** Expert: Collects matching documents in a range. Hook for optimization.
+ * Note that {@link #next()} must be called once before this method is called
+ * for the first time.
+ * @param collector The collector to which all matching documents are passed through.
+ * @param max Do not score documents past this.
+ * @return true if more matching documents may remain.
+ */
+ @Override
+ protected boolean score(Collector collector, int max, int firstDocID) throws IOException {
+ // firstDocID is ignored since nextDoc() sets 'currentDoc'
+ collector.setScorer(this);
+ while (currentDoc < max) {
+ collector.collect(currentDoc);
+ if (nextDoc() == NO_MORE_DOCS) {
+ return false;
+ }
+ }
+ return true;
+ }
+
+ @Override
+ public int nextDoc() throws IOException {
+ if (scorerDocQueue.size() < minimumNrMatchers || !advanceAfterCurrent()) {
+ currentDoc = NO_MORE_DOCS;
+ }
+ return currentDoc;
+ }
+
+ /** Advance all subscorers after the current document determined by the
+ * top of the <code>scorerDocQueue</code>.
+ * Repeat until at least the minimum number of subscorers match on the same
+ * document and all subscorers are after that document or are exhausted.
+ * <br>On entry the <code>scorerDocQueue</code> has at least <code>minimumNrMatchers</code>
+ * available. At least the scorer with the minimum document number will be advanced.
+ * @return true iff there is a match.
+ * <br>In case there is a match, </code>currentDoc</code>, </code>currentSumScore</code>,
+ * and </code>nrMatchers</code> describe the match.
+ *
+ * TODO: Investigate whether it is possible to use skipTo() when
+ * the minimum number of matchers is bigger than one, ie. try and use the
+ * character of ConjunctionScorer for the minimum number of matchers.
+ * Also delay calling score() on the sub scorers until the minimum number of
+ * matchers is reached.
+ * <br>For this, a Scorer array with minimumNrMatchers elements might
+ * hold Scorers at currentDoc that are temporarily popped from scorerQueue.
+ */
+ protected boolean advanceAfterCurrent() throws IOException {
+ do { // repeat until minimum nr of matchers
+ currentDoc = scorerDocQueue.topDoc();
+ currentScore = scorerDocQueue.topScore();
+ nrMatchers = 1;
+ do { // Until all subscorers are after currentDoc
+ if (!scorerDocQueue.topNextAndAdjustElsePop()) {
+ if (scorerDocQueue.size() == 0) {
+ break; // nothing more to advance, check for last match.
+ }
+ }
+ if (scorerDocQueue.topDoc() != currentDoc) {
+ break; // All remaining subscorers are after currentDoc.
+ }
+ currentScore += scorerDocQueue.topScore();
+ nrMatchers++;
+ } while (true);
+
+ if (nrMatchers >= minimumNrMatchers) {
+ return true;
+ } else if (scorerDocQueue.size() < minimumNrMatchers) {
+ return false;
+ }
+ } while (true);
+ }
+
+ /** Returns the score of the current document matching the query.
+ * Initially invalid, until {@link #nextDoc()} is called the first time.
+ */
+ @Override
+ public float score() throws IOException { return (float)currentScore; }
+
+ @Override
+ public int docID() {
+ return currentDoc;
+ }
+
+ /** Returns the number of subscorers matching the current document.
+ * Initially invalid, until {@link #nextDoc()} is called the first time.
+ */
+ public int nrMatchers() {
+ return nrMatchers;
+ }
+
+ /**
+ * Advances to the first match beyond the current whose document number is
+ * greater than or equal to a given target. <br>
+ * The implementation uses the skipTo() method on the subscorers.
+ *
+ * @param target
+ * The target document number.
+ * @return the document whose number is greater than or equal to the given
+ * target, or -1 if none exist.
+ */
+ @Override
+ public int advance(int target) throws IOException {
+ if (scorerDocQueue.size() < minimumNrMatchers) {
+ return currentDoc = NO_MORE_DOCS;
+ }
+ if (target <= currentDoc) {
+ return currentDoc;
+ }
+ do {
+ if (scorerDocQueue.topDoc() >= target) {
+ return advanceAfterCurrent() ? currentDoc : (currentDoc = NO_MORE_DOCS);
+ } else if (!scorerDocQueue.topSkipToAndAdjustElsePop(target)) {
+ if (scorerDocQueue.size() < minimumNrMatchers) {
+ return currentDoc = NO_MORE_DOCS;
+ }
+ }
+ } while (true);
+ }
+}
fnp / pylucene.git / blobdiff