Package org.apache.jackrabbit.core.query.lucene

Source Code of org.apache.jackrabbit.core.query.lucene.MatchAllWeight

/*
* 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.jackrabbit.core.query.lucene;

import org.apache.lucene.index.IndexReader;
import org.apache.lucene.search.Explanation;
import org.apache.lucene.search.Query;
import org.apache.lucene.search.Scorer;
import org.apache.lucene.search.Searcher;
import org.apache.lucene.search.Similarity;
import org.apache.lucene.search.Weight;

import java.io.IOException;

/**
* This class implements the Weight calculation for the MatchAllQuery.
*/
class MatchAllWeight implements Weight {

    /**
     * the MatchAllQuery
     */
    private final Query query;

    private final String field;

    /**
     * the current Searcher instance
     */
    private final Searcher searcher;

    /**
     * the weight value
     */
    private float value;

    /**
     * doc frequency for this weight
     */
    private float idf;

    /**
     * the query weight
     */
    private float queryWeight;

    /**
     * @param query
     * @param searcher
     */
    MatchAllWeight(Query query, Searcher searcher, String field) {
        this.query = query;
        this.searcher = searcher;
        this.field = field;
    }

    /**
     * {@inheritDoc}
     */
    public Query getQuery() {
        return query;
    }

    /**
     * {@inheritDoc}
     */
    public float getValue() {
        return value;
    }

    /**
     * {@inheritDoc}
     */
    public float sumOfSquaredWeights() throws IOException {
        idf = searcher.getSimilarity().idf(searcher.maxDoc(), searcher.maxDoc()); // compute idf
        queryWeight = idf * 1.0f; // boost         // compute query weight
        return queryWeight * queryWeight;           // square it
    }

    /**
     * {@inheritDoc}
     */
    public void normalize(float queryNorm) {
        queryWeight *= queryNorm;                   // normalize query weight
        value = queryWeight * idf;                  // idf for document
    }

    /**
     * {@inheritDoc}
     */
    public Scorer scorer(IndexReader reader) throws IOException {
        return new MatchAllScorer(reader, field);
    }

    /**
     * {@inheritDoc}
     */
    public Explanation explain(IndexReader reader, int doc) throws IOException {
        return new Explanation(Similarity.getDefault().idf(reader.maxDoc(), reader.maxDoc()),
                "matchAll");
    }
}
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