parentaxisquery.java

来自「jsr170接口的java实现。是个apache的开源项目。」· Java 代码 · 共 323 行

/*
 * 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.search.Query;
import org.apache.lucene.search.Scorer;
import org.apache.lucene.search.Weight;
import org.apache.lucene.search.Searcher;
import org.apache.lucene.search.Explanation;
import org.apache.lucene.search.Similarity;
import org.apache.lucene.search.HitCollector;
import org.apache.lucene.index.IndexReader;
import org.apache.lucene.index.Term;
import org.apache.lucene.index.TermDocs;

import java.io.IOException;
import java.util.BitSet;
import java.util.Map;
import java.util.HashMap;
import java.util.Set;

/**
 * <code>ParentAxisQuery</code> selects the parent nodes of a context query.
 */
class ParentAxisQuery extends Query {

    /**
     * Default score is 1.0f.
     */
    private static final Float DEFAULT_SCORE = new Float(1.0f);

    /**
     * The context query
     */
    private final Query contextQuery;

    /**
     * The nameTest to apply on the parent axis, or <code>null</code> if any
     * parent node should be selected.
     */
    private final String nameTest;

    /**
     * The scorer of the context query
     */
    private Scorer contextScorer;

    /**
     * Creates a new <code>ParentAxisQuery</code> based on a
     * <code>context</code> query.
     *
     * @param context  the context for this query.
     * @param nameTest a name test or <code>null</code> if any parent node is
     *                 selected.
     */
    ParentAxisQuery(Query context, String nameTest) {
        this.contextQuery = context;
        this.nameTest = nameTest;
    }

    /**
     * Creates a <code>Weight</code> instance for this query.
     *
     * @param searcher the <code>Searcher</code> instance to use.
     * @return a <code>ParentAxisWeight</code>.
     */
    protected Weight createWeight(Searcher searcher) {
        return new ParentAxisWeight(searcher);
    }

    /**
     * {@inheritDoc}
     */
    public void extractTerms(Set terms) {
        contextQuery.extractTerms(terms);
    }

    /**
     * {@inheritDoc}
     */
    public Query rewrite(IndexReader reader) throws IOException {
        Query cQuery = contextQuery.rewrite(reader);
        if (cQuery == contextQuery) {
            return this;
        } else {
            return new ParentAxisQuery(cQuery, nameTest);
        }
    }

    /**
     * Always returns 'ParentAxisQuery'.
     *
     * @param field the name of a field.
     * @return 'ParentAxisQuery'.
     */
    public String toString(String field) {
        return "ParentAxisQuery";
    }

    //-----------------------< ParentAxisWeight >-------------------------------

    /**
     * The <code>Weight</code> implementation for this <code>ParentAxisQuery</code>.
     */
    private class ParentAxisWeight implements Weight {

        /**
         * The searcher in use
         */
        private final Searcher searcher;

        /**
         * Creates a new <code>ParentAxisWeight</code> instance using
         * <code>searcher</code>.
         *
         * @param searcher a <code>Searcher</code> instance.
         */
        private ParentAxisWeight(Searcher searcher) {
            this.searcher = searcher;
        }

        /**
         * Returns this <code>ParentAxisQuery</code>.
         *
         * @return this <code>ParentAxisQuery</code>.
         */
        public Query getQuery() {
            return ParentAxisQuery.this;
        }

        /**
         * {@inheritDoc}
         */
        public float getValue() {
            return 1.0f;
        }

        /**
         * {@inheritDoc}
         */
        public float sumOfSquaredWeights() throws IOException {
            return 1.0f;
        }

        /**
         * {@inheritDoc}
         */
        public void normalize(float norm) {
        }

        /**
         * Creates a scorer for this <code>ParentAxisQuery</code>.
         *
         * @param reader a reader for accessing the index.
         * @return a <code>ParentAxisScorer</code>.
         * @throws IOException if an error occurs while reading from the index.
         */
        public Scorer scorer(IndexReader reader) throws IOException {
            contextScorer = contextQuery.weight(searcher).scorer(reader);
            HierarchyResolver resolver = (HierarchyResolver) reader;
            return new ParentAxisScorer(searcher.getSimilarity(), reader, resolver);
        }

        /**
         * {@inheritDoc}
         */
        public Explanation explain(IndexReader reader, int doc) throws IOException {
            return new Explanation();
        }
    }

    //--------------------------< ParentAxisScorer >----------------------------

    /**
     * Implements a <code>Scorer</code> for this <code>ParentAxisQuery</code>.
     */
    private class ParentAxisScorer extends Scorer {

        /**
         * An <code>IndexReader</code> to access the index.
         */
        private final IndexReader reader;

        /**
         * The <code>HierarchyResolver</code> of the index.
         */
        private final HierarchyResolver hResolver;

        /**
         * BitSet storing the id's of selected documents
         */
        private BitSet hits;

        /**
         * Map that contains the scores from matching documents from the context
         * query. To save memory only scores that are not equal to 1.0f are put
         * to this map.
         * <p/>
         * key=[Integer] id of selected document from context query<br>
         * value=[Float] score for that document
         */
        private final Map scores = new HashMap();

        /**
         * The next document id to return
         */
        private int nextDoc = -1;

        /**
         * Creates a new <code>ParentAxisScorer</code>.
         *
         * @param similarity the <code>Similarity</code> instance to use.
         * @param reader     for index access.
         */
        protected ParentAxisScorer(Similarity similarity, IndexReader reader, HierarchyResolver resolver) {
            super(similarity);
            this.reader = reader;
            this.hResolver = resolver;
        }

        /**
         * {@inheritDoc}
         */
        public boolean next() throws IOException {
            calculateParent();
            nextDoc = hits.nextSetBit(nextDoc + 1);
            return nextDoc > -1;
        }

        /**
         * {@inheritDoc}
         */
        public int doc() {
            return nextDoc;
        }

        /**
         * {@inheritDoc}
         */
        public float score() throws IOException {
            Float score = (Float) scores.get(new Integer(nextDoc));
            if (score == null) {
                score = DEFAULT_SCORE;
            }
            return score.floatValue();
        }

        /**
         * {@inheritDoc}
         */
        public boolean skipTo(int target) throws IOException {
            calculateParent();
            nextDoc = hits.nextSetBit(target);
            return nextDoc > -1;
        }

        /**
         * {@inheritDoc}
         *
         * @throws UnsupportedOperationException this implementation always
         *                                       throws an <code>UnsupportedOperationException</code>.
         */
        public Explanation explain(int doc) throws IOException {
            throw new UnsupportedOperationException();
        }

        private void calculateParent() throws IOException {
            if (hits == null) {
                hits = new BitSet(reader.maxDoc());

                final IOException[] ex = new IOException[1];
                contextScorer.score(new HitCollector() {
                    public void collect(int doc, float score) {
                        try {
                            doc = hResolver.getParent(doc);
                            if (doc != -1) {
                                hits.set(doc);
                                if (score != DEFAULT_SCORE.floatValue()) {
                                    scores.put(new Integer(doc), new Float(score));
                                }
                            }
                        } catch (IOException e) {
                            ex[0] = e;
                        }
                    }
                });

                if (ex[0] != null) {
                    throw ex[0];
                }

                // filter out documents that do not match the name test
                if (nameTest != null) {
                    TermDocs tDocs = reader.termDocs(new Term(FieldNames.LABEL, nameTest));
                    try {
                        for (int i = hits.nextSetBit(0); i >= 0; i = hits.nextSetBit(i + 1)) {
                            if (!tDocs.skipTo(i)) {
                                hits.clear(i);
                            }
                        }
                    } finally {
                        tDocs.close();
                    }
                }
            }
        }
    }
}