/*
* 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 IndexReaderLucene.Net.Index.IndexReader;
namespace Lucene.Net.Search{
/// <summary>Expert: Calculate query weights and build query scorers.
/// <p>
/// The purpose of Weight is to make it so that searching does not modify
/// a Query, so that a Query instance can be reused. <br>
/// Searcher dependent state of the query should reside in the Weight. <br>
/// IndexReader dependent state should reside in the Scorer.
/// <p>
/// A <code>Weight</code> is used in the following way:
/// <ol>
/// <li>A <code>Weight</code> is constructed by a top-level query,
/// given a <code>Searcher</code> ({@link Query#CreateWeight(Searcher)}).
/// <li>The {@link #SumOfSquaredWeights()} method is called
/// on the <code>Weight</code> to compute
/// the query normalization factor {@link Similarity#QueryNorm(float)}
/// of the query clauses contained in the query.
/// <li>The query normalization factor is passed to {@link #Normalize(float)}.
/// At this point the weighting is complete.
/// <li>A <code>Scorer</code> is constructed by {@link #Scorer(IndexReader)}.
/// </ol>
/// </summary>
public interface Weight
{
/// <summary>The query that this concerns. </summary>
Query GetQuery();
/// <summary>The weight for this query. </summary>
float GetValue();
/// <summary>The sum of squared weights of contained query clauses. </summary>
float SumOfSquaredWeights();
/// <summary>Assigns the query normalization factor to this. </summary>
void Normalize(float norm);
/// <summary>Constructs a scorer for this. </summary>
Scorer Scorer(IndexReader reader);
/// <summary>An explanation of the score computation for the named document. </summary>
Explanation Explain(IndexReader reader, int doc);
}
}
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