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 doc 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.
- *
- * Subclasses can override this method to modify the custom score. - *
- * 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. - *
- * The default computation herein is a multiplication of given scores: - *
- * ModifiedScore = valSrcScore * valSrcScores[0] * valSrcScores[1] * ... - *- * - * @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. - *
- * Subclasses can override this method to modify the custom score. - *
- * 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. - *
- * The default computation herein is a multiplication of the two scores: - *
- * ModifiedScore = subQueryScore * valSrcScore - *- * - * @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; - } - -}