/*
* 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.jackrabbit.spi.Name;
import org.apache.lucene.index.IndexReader;
import org.apache.lucene.search.FieldComparator;
import org.apache.lucene.search.ScoreDoc;
import org.apache.lucene.search.SortField;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.Comparator;
import java.util.Iterator;
import java.util.List;
/**
* <code>SortedMultiColumnQueryHits</code> implements sorting of query hits
* based on {@link Ordering}s.
*/
public class SortedMultiColumnQueryHits extends FilterMultiColumnQueryHits {
/**
* Iterator over sorted ScoreNode[]s.
*/
private final Iterator<ScoreNode[]> it;
/**
* Creates sorted query hits.
*
* @param hits the hits to sort.
* @param orderings the ordering specifications.
* @param reader the current index reader.
* @throws IOException if an error occurs while reading from the index.
*/
public SortedMultiColumnQueryHits(MultiColumnQueryHits hits,
Ordering[] orderings,
IndexReader reader)
throws IOException {
super(hits);
List<ScoreNode[]> sortedHits = new ArrayList<ScoreNode[]>();
ScoreNode[] next;
while ((next = hits.nextScoreNodes()) != null) {
sortedHits.add(next);
}
try {
Collections.sort(sortedHits, new ScoreNodeComparator(
reader, orderings, hits.getSelectorNames(), sortedHits.size()));
} catch (RuntimeException e) {
// might be thrown by ScoreNodeComparator#compare
throw Util.createIOException(e);
}
this.it = sortedHits.iterator();
}
/**
* {@inheritDoc}
*/
public ScoreNode[] nextScoreNodes() throws IOException {
if (it.hasNext()) {
return it.next();
} else {
return null;
}
}
/**
* {@inheritDoc}
*/
public void skip(int n) throws IOException {
while (n-- > 0) {
nextScoreNodes();
}
}
/**
* A comparator that compares ScoreNode[].
*/
private static final class ScoreNodeComparator
implements Comparator<ScoreNode[]> {
/**
* The current index reader.
*/
private final IndexReader reader;
/**
* The ordering specifications.
*/
private final Ordering[] orderings;
/**
* The selector name index for each of the {@link #orderings}.
*/
private final int[] idx;
/**
* The score doc comparator for each of the {@link #orderings}.
*/
private final ScoreDocComparator[] comparators;
/**
* The reverse flag for each of the {@link #orderings}.
*/
private final boolean[] isReverse;
/**
* Reusable ScoreDoc for use in {@link #compare(ScoreNode[], ScoreNode[])}.
*/
private final ScoreDoc doc1 = new ScoreDoc(0, 1.0f);
/**
* Reusable ScoreDoc for use in {@link #compare(ScoreNode[], ScoreNode[])}.
*/
private final ScoreDoc doc2 = new ScoreDoc(0, 1.0f);
/**
* Creates a new comparator.
*
* @param reader the current index reader.
* @param orderings the ordering specifications.
* @param selectorNames the selector names associated with the
* ScoreNode[] used in
* {@link #compare(ScoreNode[], ScoreNode[])}.
* @throws IOException if an error occurs while reading from the index.
*/
private ScoreNodeComparator(IndexReader reader,
Ordering[] orderings,
Name[] selectorNames,
int numHits)
throws IOException {
this.reader = reader;
this.orderings = orderings;
List names = Arrays.asList(selectorNames);
this.idx = new int[orderings.length];
this.comparators = new ScoreDocComparator[orderings.length];
this.isReverse = new boolean[orderings.length];
for (int i = 0; i < orderings.length; i++) {
idx[i] = names.indexOf(orderings[i].getSelectorName());
SortField sf = orderings[i].getSortField();
if (sf.getComparatorSource() != null) {
FieldComparator c = sf.getComparatorSource().newComparator(sf.getField(), numHits, 0, false);
assert c instanceof FieldComparatorBase;
comparators[i] = new ScoreDocComparator((FieldComparatorBase) c);
comparators[i].setNextReader(reader, 0);
}
isReverse[i] = sf.getReverse();
}
}
/**
* {@inheritDoc}
*/
public int compare(ScoreNode[] sn1, ScoreNode[] sn2) {
for (int i = 0; i < orderings.length; i++) {
int c;
int scoreNodeIndex = idx[i];
ScoreNode n1 = sn1[scoreNodeIndex];
ScoreNode n2 = sn2[scoreNodeIndex];
if (n1 == n2) {
continue;
} else if (n1 == null) {
c = -1;
} else if (n2 == null) {
c = 1;
} else if (comparators[i] != null) {
try {
doc1.doc = n1.getDoc(reader);
doc1.score = n1.getScore();
doc2.doc = n2.getDoc(reader);
doc2.score = n2.getScore();
} catch (IOException e) {
throw new RuntimeException(e.getMessage(), e);
}
c = comparators[i].compareDocs(doc1.doc, doc2.doc);
} else {
// compare score
c = new Float(n1.getScore()).compareTo(n2.getScore());
}
if (c != 0) {
if (isReverse[i]) {
c = -c;
}
return c;
}
}
return 0;
}
}
private static final class ScoreDocComparator extends FieldComparatorDecorator {
public ScoreDocComparator(FieldComparatorBase base) {
super(base);
}
public int compareDocs(int doc1, int doc2) {
return compare(sortValue(doc1), sortValue(doc2));
}
}
}