--- /dev/null
+package org.apache.lucene.search.function;
+
+/**
+ * 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.io.IOException;
+
+import org.apache.lucene.index.IndexReader;
+import org.apache.lucene.search.Explanation;
+import org.apache.lucene.search.FieldCache; // for javadocs
+
+/**
+ * An instance of this subclass should be returned by
+ * {@link CustomScoreQuery#getCustomScoreProvider}, if you want
+ * to modify the custom score calculation of a {@link CustomScoreQuery}.
+ * <p>Since Lucene 2.9, queries operate on each segment of an index separately,
+ * so the protected {@link #reader} field can be used to resolve doc IDs,
+ * as the supplied <code>doc</code> ID is per-segment and without knowledge
+ * of the IndexReader you cannot access the document or {@link FieldCache}.
+ *
+ * @lucene.experimental
+ * @since 2.9.2
+ */
+public class CustomScoreProvider {
+
+ protected final IndexReader reader;
+
+ /**
+ * Creates a new instance of the provider class for the given {@link IndexReader}.
+ */
+ public CustomScoreProvider(IndexReader reader) {
+ this.reader = reader;
+ }
+
+ /**
+ * Compute a custom score by the subQuery score and a number of
+ * {@link ValueSourceQuery} scores.
+ * <p>
+ * Subclasses can override this method to modify the custom score.
+ * <p>
+ * If your custom scoring is different than the default herein you
+ * should override at least one of the two customScore() methods.
+ * If the number of ValueSourceQueries is always < 2 it is
+ * sufficient to override the other
+ * {@link #customScore(int, float, float) customScore()}
+ * method, which is simpler.
+ * <p>
+ * The default computation herein is a multiplication of given scores:
+ * <pre>
+ * ModifiedScore = valSrcScore * valSrcScores[0] * valSrcScores[1] * ...
+ * </pre>
+ *
+ * @param doc id of scored doc.
+ * @param subQueryScore score of that doc by the subQuery.
+ * @param valSrcScores scores of that doc by the ValueSourceQuery.
+ * @return custom score.
+ */
+ public float customScore(int doc, float subQueryScore, float valSrcScores[]) throws IOException {
+ if (valSrcScores.length == 1) {
+ return customScore(doc, subQueryScore, valSrcScores[0]);
+ }
+ if (valSrcScores.length == 0) {
+ return customScore(doc, subQueryScore, 1);
+ }
+ float score = subQueryScore;
+ for(int i = 0; i < valSrcScores.length; i++) {
+ score *= valSrcScores[i];
+ }
+ return score;
+ }
+
+ /**
+ * Compute a custom score by the subQuery score and the ValueSourceQuery score.
+ * <p>
+ * Subclasses can override this method to modify the custom score.
+ * <p>
+ * If your custom scoring is different than the default herein you
+ * should override at least one of the two customScore() methods.
+ * If the number of ValueSourceQueries is always < 2 it is
+ * sufficient to override this customScore() method, which is simpler.
+ * <p>
+ * The default computation herein is a multiplication of the two scores:
+ * <pre>
+ * ModifiedScore = subQueryScore * valSrcScore
+ * </pre>
+ *
+ * @param doc id of scored doc.
+ * @param subQueryScore score of that doc by the subQuery.
+ * @param valSrcScore score of that doc by the ValueSourceQuery.
+ * @return custom score.
+ */
+ public float customScore(int doc, float subQueryScore, float valSrcScore) throws IOException {
+ return subQueryScore * valSrcScore;
+ }
+
+ /**
+ * Explain the custom score.
+ * Whenever overriding {@link #customScore(int, float, float[])},
+ * this method should also be overridden to provide the correct explanation
+ * for the part of the custom scoring.
+ *
+ * @param doc doc being explained.
+ * @param subQueryExpl explanation for the sub-query part.
+ * @param valSrcExpls explanation for the value source part.
+ * @return an explanation for the custom score
+ */
+ public Explanation customExplain(int doc, Explanation subQueryExpl, Explanation valSrcExpls[]) throws IOException {
+ if (valSrcExpls.length == 1) {
+ return customExplain(doc, subQueryExpl, valSrcExpls[0]);
+ }
+ if (valSrcExpls.length == 0) {
+ return subQueryExpl;
+ }
+ float valSrcScore = 1;
+ for (int i = 0; i < valSrcExpls.length; i++) {
+ valSrcScore *= valSrcExpls[i].getValue();
+ }
+ Explanation exp = new Explanation( valSrcScore * subQueryExpl.getValue(), "custom score: product of:");
+ exp.addDetail(subQueryExpl);
+ for (int i = 0; i < valSrcExpls.length; i++) {
+ exp.addDetail(valSrcExpls[i]);
+ }
+ return exp;
+ }
+
+ /**
+ * Explain the custom score.
+ * Whenever overriding {@link #customScore(int, float, float)},
+ * this method should also be overridden to provide the correct explanation
+ * for the part of the custom scoring.
+ *
+ * @param doc doc being explained.
+ * @param subQueryExpl explanation for the sub-query part.
+ * @param valSrcExpl explanation for the value source part.
+ * @return an explanation for the custom score
+ */
+ public Explanation customExplain(int doc, Explanation subQueryExpl, Explanation valSrcExpl) throws IOException {
+ float valSrcScore = 1;
+ if (valSrcExpl != null) {
+ valSrcScore *= valSrcExpl.getValue();
+ }
+ Explanation exp = new Explanation( valSrcScore * subQueryExpl.getValue(), "custom score: product of:");
+ exp.addDetail(subQueryExpl);
+ exp.addDetail(valSrcExpl);
+ return exp;
+ }
+
+}
fnp / pylucene.git / blobdiff