| /* |
| * 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. |
| */ |
| package org.apache.lucene.search.similarities; |
| |
| import org.apache.lucene.index.FieldInvertState; |
| import org.apache.lucene.search.CollectionStatistics; |
| import org.apache.lucene.search.Explanation; |
| import org.apache.lucene.search.TermStatistics; |
| |
| /** |
| * Simple similarity that gives terms a score that is equal to their query |
| * boost. This similarity is typically used with disabled norms since neither |
| * document statistics nor index statistics are used for scoring. That said, |
| * if norms are enabled, they will be computed the same way as |
| * {@link SimilarityBase} and {@link BM25Similarity} with |
| * {@link SimilarityBase#setDiscountOverlaps(boolean) discounted overlaps} |
| * so that the {@link Similarity} can be changed after the index has been |
| * created. |
| */ |
| public class BooleanSimilarity extends Similarity { |
| |
| private static final Similarity BM25_SIM = new BM25Similarity(); |
| |
| /** Sole constructor */ |
| public BooleanSimilarity() {} |
| |
| @Override |
| public long computeNorm(FieldInvertState state) { |
| return BM25_SIM.computeNorm(state); |
| } |
| |
| @Override |
| public SimScorer scorer(float boost, CollectionStatistics collectionStats, TermStatistics... termStats) { |
| return new BooleanWeight(boost); |
| } |
| |
| private static class BooleanWeight extends SimScorer { |
| final float boost; |
| |
| BooleanWeight(float boost) { |
| this.boost = boost; |
| } |
| |
| @Override |
| public float score(float freq, long norm) { |
| return boost; |
| } |
| |
| @Override |
| public Explanation explain(Explanation freq, long norm) { |
| Explanation queryBoostExpl = Explanation.match(boost, "boost, query boost"); |
| return Explanation.match( |
| queryBoostExpl.getValue(), |
| "score(" + getClass().getSimpleName() + "), computed from:", |
| queryBoostExpl); |
| } |
| } |
| |
| } |