 | Report generated by Clover Code Coverage v2.3.0 Fri May 9 2008 10:54:33 EST. |
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| 1 | package org.apache.lucene.search; | |
| 2 | ||
| 3 | /** | |
| 4 | * Copyright 2004 The Apache Software Foundation | |
| 5 | * | |
| 6 | * Licensed under the Apache License, Version 2.0 (the "License"); | |
| 7 | * you may not use this file except in compliance with the License. | |
| 8 | * You may obtain a copy of the License at | |
| 9 | * | |
| 10 | * http://www.apache.org/licenses/LICENSE-2.0 | |
| 11 | * | |
| 12 | * Unless required by applicable law or agreed to in writing, software | |
| 13 | * distributed under the License is distributed on an "AS IS" BASIS, | |
| 14 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | |
| 15 | * See the License for the specific language governing permissions and | |
| 16 | * limitations under the License. | |
| 17 | */ | |
| 18 | ||
| 19 | import java.io.IOException; | |
| 20 | ||
| 21 | import org.apache.lucene.index.IndexReader; | |
| 22 | ||
| 23 | /** Expert: Calculate query weights and build query scorers. | |
| 24 | * <p> | |
| 25 | * The purpose of Weight is to make it so that searching does not modify | |
| 26 | * a Query, so that a Query instance can be reused. <br> | |
| 27 | * Searcher dependent state of the query should reside in the Weight. <br> | |
| 28 | * IndexReader dependent state should reside in the Scorer. | |
| 29 | * <p> | |
| 30 | * A <code>Weight</code> is used in the following way: | |
| 31 | * <ol> | |
| 32 | * <li>A <code>Weight</code> is constructed by a top-level query, | |
| 33 | * given a <code>Searcher</code> ({@link Query#createWeight(Searcher)}). | |
| 34 | * <li>The {@link #sumOfSquaredWeights()} method is called | |
| 35 | * on the <code>Weight</code> to compute | |
| 36 | * the query normalization factor {@link Similarity#queryNorm(float)} | |
| 37 | * of the query clauses contained in the query. | |
| 38 | * <li>The query normalization factor is passed to {@link #normalize(float)}. | |
| 39 | * At this point the weighting is complete. | |
| 40 | * <li>A <code>Scorer</code> is constructed by {@link #scorer(IndexReader)}. | |
| 41 | * </ol> | |
| 42 | */ | |
| 43 | public interface Weight extends java.io.Serializable { | |
| 44 | /** The query that this concerns. */ | |
| 45 | Query getQuery(); | |
| 46 | ||
| 47 | /** The weight for this query. */ | |
| 48 | float getValue(); | |
| 49 | ||
| 50 | /** The sum of squared weights of contained query clauses. */ | |
| 51 | float sumOfSquaredWeights() throws IOException; | |
| 52 | ||
| 53 | /** Assigns the query normalization factor to this. */ | |
| 54 | void normalize(float norm); | |
| 55 | ||
| 56 | /** Constructs a scorer for this. */ | |
| 57 | Scorer scorer(IndexReader reader) throws IOException; | |
| 58 | ||
| 59 | /** An explanation of the score computation for the named document. */ | |
| 60 | Explanation explain(IndexReader reader, int doc) throws IOException; | |
| 61 | } | |
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