/* * Copyright 2004 The Apache Software Foundation * * Licensed 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. */ using System; using IndexReader = Lucene.Net.Index.IndexReader; namespace Lucene.Net.Search { /// Expert: Calculate query weights and build query scorers. ///

/// The purpose of Weight is to make it so that searching does not modify /// a Query, so that a Query instance can be reused.
/// Searcher dependent state of the query should reside in the Weight.
/// IndexReader dependent state should reside in the Scorer. ///

/// A Weight is used in the following way: ///

    ///
  1. A Weight is constructed by a top-level query, /// given a Searcher ({@link Query#CreateWeight(Searcher)}). ///
  2. The {@link #SumOfSquaredWeights()} method is called /// on the Weight to compute /// the query normalization factor {@link Similarity#QueryNorm(float)} /// of the query clauses contained in the query. ///
  3. The query normalization factor is passed to {@link #normalize(float)}. /// At this point the weighting is complete. ///
  4. A Scorer is constructed by {@link #Scorer(IndexReader)}. ///
///
public interface Weight { /// The query that this concerns. Query GetQuery(); /// The weight for this query. float GetValue(); /// The sum of squared weights of contained query clauses. float SumOfSquaredWeights(); /// Assigns the query normalization factor to this. void Normalize(float norm); /// Constructs a scorer for this. Scorer Scorer(IndexReader reader); /// An explanation of the score computation for the named document. Explanation Explain(IndexReader reader, int doc); } }