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Package for Faceted Indexing and Search
/*
* 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.lucene.facet;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import org.apache.lucene.index.LeafReaderContext;
import org.apache.lucene.search.Collector;
import org.apache.lucene.search.DocIdSet;
import org.apache.lucene.search.FieldDoc;
import org.apache.lucene.search.IndexSearcher;
import org.apache.lucene.search.MultiCollector;
import org.apache.lucene.search.Query;
import org.apache.lucene.search.ScoreDoc;
import org.apache.lucene.search.Scorer;
import org.apache.lucene.search.SimpleCollector;
import org.apache.lucene.search.Sort;
import org.apache.lucene.search.TopDocs;
import org.apache.lucene.search.TopDocsCollector;
import org.apache.lucene.search.TopFieldCollector;
import org.apache.lucene.search.TopFieldDocs;
import org.apache.lucene.search.TopScoreDocCollector;
import org.apache.lucene.search.TotalHitCountCollector;
import org.apache.lucene.util.ArrayUtil;
import org.apache.lucene.util.DocIdSetBuilder;
/** Collects hits for subsequent faceting. Once you've run
* a search and collect hits into this, instantiate one of
* the {@link Facets} subclasses to do the facet
* counting. Use the {@code search} utility methods to
* perform an "ordinary" search but also collect into a
* {@link Collector}. */
// redundant 'implements Collector' to workaround javadocs bugs
public class FacetsCollector extends SimpleCollector implements Collector {
private LeafReaderContext context;
private Scorer scorer;
private int totalHits;
private float[] scores;
private final boolean keepScores;
private final List matchingDocs = new ArrayList<>();
private DocIdSetBuilder docsBuilder;
/**
* Holds the documents that were matched in the {@link org.apache.lucene.index.LeafReaderContext}.
* If scores were required, then {@code scores} is not null.
*/
public final static class MatchingDocs {
/** Context for this segment. */
public final LeafReaderContext context;
/** Which documents were seen. */
public final DocIdSet bits;
/** Non-sparse scores array. */
public final float[] scores;
/** Total number of hits */
public final int totalHits;
/** Sole constructor. */
public MatchingDocs(LeafReaderContext context, DocIdSet bits, int totalHits, float[] scores) {
this.context = context;
this.bits = bits;
this.scores = scores;
this.totalHits = totalHits;
}
}
/** Default constructor */
public FacetsCollector() {
this(false);
}
/** Create this; if {@code keepScores} is true then a
* float[] is allocated to hold score of all hits. */
public FacetsCollector(boolean keepScores) {
this.keepScores = keepScores;
}
/** True if scores were saved. */
public final boolean getKeepScores() {
return keepScores;
}
/**
* Returns the documents matched by the query, one {@link MatchingDocs} per
* visited segment.
*/
public List getMatchingDocs() {
if (docsBuilder != null) {
matchingDocs.add(new MatchingDocs(this.context, docsBuilder.build(), totalHits, scores));
docsBuilder = null;
scores = null;
context = null;
}
return matchingDocs;
}
@Override
public final void collect(int doc) throws IOException {
docsBuilder.grow(1).add(doc);
if (keepScores) {
if (totalHits >= scores.length) {
float[] newScores = new float[ArrayUtil.oversize(totalHits + 1, 4)];
System.arraycopy(scores, 0, newScores, 0, totalHits);
scores = newScores;
}
scores[totalHits] = scorer.score();
}
totalHits++;
}
@Override
public boolean needsScores() {
return true;
}
@Override
public final void setScorer(Scorer scorer) throws IOException {
this.scorer = scorer;
}
@Override
protected void doSetNextReader(LeafReaderContext context) throws IOException {
if (docsBuilder != null) {
matchingDocs.add(new MatchingDocs(this.context, docsBuilder.build(), totalHits, scores));
}
docsBuilder = new DocIdSetBuilder(context.reader().maxDoc());
totalHits = 0;
if (keepScores) {
scores = new float[64]; // some initial size
}
this.context = context;
}
/** Utility method, to search and also collect all hits
* into the provided {@link Collector}. */
public static TopDocs search(IndexSearcher searcher, Query q, int n, Collector fc) throws IOException {
return doSearch(searcher, null, q, n, null, false, false, fc);
}
/** Utility method, to search and also collect all hits
* into the provided {@link Collector}. */
public static TopFieldDocs search(IndexSearcher searcher, Query q, int n, Sort sort, Collector fc) throws IOException {
if (sort == null) {
throw new IllegalArgumentException("sort must not be null");
}
return (TopFieldDocs) doSearch(searcher, null, q, n, sort, false, false, fc);
}
/** Utility method, to search and also collect all hits
* into the provided {@link Collector}. */
public static TopFieldDocs search(IndexSearcher searcher, Query q, int n, Sort sort, boolean doDocScores, boolean doMaxScore, Collector fc) throws IOException {
if (sort == null) {
throw new IllegalArgumentException("sort must not be null");
}
return (TopFieldDocs) doSearch(searcher, null, q, n, sort, doDocScores, doMaxScore, fc);
}
/** Utility method, to search and also collect all hits
* into the provided {@link Collector}. */
public static TopDocs searchAfter(IndexSearcher searcher, ScoreDoc after, Query q, int n, Collector fc) throws IOException {
return doSearch(searcher, after, q, n, null, false, false, fc);
}
/** Utility method, to search and also collect all hits
* into the provided {@link Collector}. */
public static TopDocs searchAfter(IndexSearcher searcher, ScoreDoc after, Query q, int n, Sort sort, Collector fc) throws IOException {
if (sort == null) {
throw new IllegalArgumentException("sort must not be null");
}
return doSearch(searcher, after, q, n, sort, false, false, fc);
}
/** Utility method, to search and also collect all hits
* into the provided {@link Collector}. */
public static TopDocs searchAfter(IndexSearcher searcher, ScoreDoc after, Query q, int n, Sort sort, boolean doDocScores, boolean doMaxScore, Collector fc) throws IOException {
if (sort == null) {
throw new IllegalArgumentException("sort must not be null");
}
return doSearch(searcher, after, q, n, sort, doDocScores, doMaxScore, fc);
}
private static TopDocs doSearch(IndexSearcher searcher, ScoreDoc after, Query q, int n, Sort sort,
boolean doDocScores, boolean doMaxScore, Collector fc) throws IOException {
int limit = searcher.getIndexReader().maxDoc();
if (limit == 0) {
limit = 1;
}
n = Math.min(n, limit);
if (after != null && after.doc >= limit) {
throw new IllegalArgumentException("after.doc exceeds the number of documents in the reader: after.doc="
+ after.doc + " limit=" + limit);
}
TopDocs topDocs = null;
if (n==0) {
TotalHitCountCollector totalHitCountCollector = new TotalHitCountCollector();
searcher.search(q, MultiCollector.wrap(totalHitCountCollector, fc));
topDocs = new TopDocs(totalHitCountCollector.getTotalHits(), new ScoreDoc[0], Float.NaN);
} else {
TopDocsCollector hitsCollector;
if (sort != null) {
if (after != null && !(after instanceof FieldDoc)) {
// TODO: if we fix type safety of TopFieldDocs we can
// remove this
throw new IllegalArgumentException("after must be a FieldDoc; got " + after);
}
boolean fillFields = true;
hitsCollector = TopFieldCollector.create(sort, n,
(FieldDoc) after,
fillFields,
doDocScores,
doMaxScore,
true); // TODO: can we disable exact hit counts
} else {
hitsCollector = TopScoreDocCollector.create(n, after);
}
searcher.search(q, MultiCollector.wrap(hitsCollector, fc));
topDocs = hitsCollector.topDocs();
}
return topDocs;
}
}