/*
* 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.search.join;
import java.io.IOException;
import java.util.Collection;
import java.util.Collections;
import java.util.Locale;
import org.apache.lucene.index.IndexReader;
import org.apache.lucene.index.LeafReaderContext;
import org.apache.lucene.search.FilterWeight;
import org.apache.lucene.search.DocIdSetIterator;
import org.apache.lucene.search.Explanation;
import org.apache.lucene.search.IndexSearcher;
import org.apache.lucene.search.Query;
import org.apache.lucene.search.Scorer;
import org.apache.lucene.search.Weight;
import org.apache.lucene.util.BitSet;
/**
* Just like {@link ToParentBlockJoinQuery}, except this
* query joins in reverse: you provide a Query matching
* parent documents and it joins down to child
* documents.
*
* @lucene.experimental
*/
public class ToChildBlockJoinQuery extends Query {
/** Message thrown from {@link
* ToChildBlockJoinScorer#validateParentDoc} on misuse,
* when the parent query incorrectly returns child docs. */
static final String INVALID_QUERY_MESSAGE = "Parent query must not match any docs besides parent filter. "
+ "Combine them as must (+) and must-not (-) clauses to find a problem doc. docID=";
static final String ILLEGAL_ADVANCE_ON_PARENT = "Expect to be advanced on child docs only. got docID=";
private final BitSetProducer parentsFilter;
private final Query parentQuery;
/**
* Create a ToChildBlockJoinQuery.
*
* @param parentQuery Query that matches parent documents
* @param parentsFilter Filter identifying the parent documents.
*/
public ToChildBlockJoinQuery(Query parentQuery, BitSetProducer parentsFilter) {
super();
this.parentQuery = parentQuery;
this.parentsFilter = parentsFilter;
}
@Override
public Weight createWeight(IndexSearcher searcher, boolean needsScores, float boost) throws IOException {
return new ToChildBlockJoinWeight(this, parentQuery.createWeight(searcher, needsScores, boost), parentsFilter, needsScores);
}
/** Return our parent query. */
public Query getParentQuery() {
return parentQuery;
}
private static class ToChildBlockJoinWeight extends FilterWeight {
private final BitSetProducer parentsFilter;
private final boolean doScores;
public ToChildBlockJoinWeight(Query joinQuery, Weight parentWeight, BitSetProducer parentsFilter, boolean doScores) {
super(joinQuery, parentWeight);
this.parentsFilter = parentsFilter;
this.doScores = doScores;
}
// NOTE: acceptDocs applies (and is checked) only in the
// child document space
@Override
public Scorer scorer(LeafReaderContext readerContext) throws IOException {
final Scorer parentScorer = in.scorer(readerContext);
if (parentScorer == null) {
// No matches
return null;
}
// NOTE: this doesn't take acceptDocs into account, the responsibility
// to not match deleted docs is on the scorer
final BitSet parents = parentsFilter.getBitSet(readerContext);
if (parents == null) {
// No parents
return null;
}
return new ToChildBlockJoinScorer(this, parentScorer, parents, doScores);
}
@Override
public Explanation explain(LeafReaderContext context, int doc) throws IOException {
ToChildBlockJoinScorer scorer = (ToChildBlockJoinScorer) scorer(context);
if (scorer != null && scorer.iterator().advance(doc) == doc) {
int parentDoc = scorer.getParentDoc();
return Explanation.match(
scorer.score(),
String.format(Locale.ROOT, "Score based on parent document %d", parentDoc + context.docBase),
in.explain(context, parentDoc)
);
}
return Explanation.noMatch("Not a match");
}
}
static class ToChildBlockJoinScorer extends Scorer {
private final Scorer parentScorer;
private final DocIdSetIterator parentIt;
private final BitSet parentBits;
private final boolean doScores;
private float parentScore;
private int parentFreq = 1;
private int childDoc = -1;
private int parentDoc = 0;
public ToChildBlockJoinScorer(Weight weight, Scorer parentScorer, BitSet parentBits, boolean doScores) {
super(weight);
this.doScores = doScores;
this.parentBits = parentBits;
this.parentScorer = parentScorer;
this.parentIt = parentScorer.iterator();
}
@Override
public Collection<ChildScorer> getChildren() {
return Collections.singleton(new ChildScorer(parentScorer, "BLOCK_JOIN"));
}
@Override
public DocIdSetIterator iterator() {
return new DocIdSetIterator() {
@Override
public int docID() {
return childDoc;
}
@Override
public int nextDoc() throws IOException {
//System.out.println("Q.nextDoc() parentDoc=" + parentDoc + " childDoc=" + childDoc);
while (true) {
if (childDoc+1 == parentDoc) {
// OK, we are done iterating through all children
// matching this one parent doc, so we now nextDoc()
// the parent. Use a while loop because we may have
// to skip over some number of parents w/ no
// children:
while (true) {
parentDoc = parentIt.nextDoc();
validateParentDoc();
if (parentDoc == 0) {
// Degenerate but allowed: first parent doc has no children
// TODO: would be nice to pull initial parent
// into ctor so we can skip this if... but it's
// tricky because scorer must return -1 for
// .doc() on init...
parentDoc = parentIt.nextDoc();
validateParentDoc();
}
if (parentDoc == NO_MORE_DOCS) {
childDoc = NO_MORE_DOCS;
//System.out.println(" END");
return childDoc;
}
// Go to first child for this next parentDoc:
childDoc = 1 + parentBits.prevSetBit(parentDoc-1);
if (childDoc == parentDoc) {
// This parent has no children; continue
// parent loop so we move to next parent
continue;
}
if (childDoc < parentDoc) {
if (doScores) {
parentScore = parentScorer.score();
parentFreq = parentScorer.freq();
}
//System.out.println(" " + childDoc);
return childDoc;
} else {
// Degenerate but allowed: parent has no children
}
}
} else {
assert childDoc < parentDoc: "childDoc=" + childDoc + " parentDoc=" + parentDoc;
childDoc++;
//System.out.println(" " + childDoc);
return childDoc;
}
}
}
@Override
public int advance(int childTarget) throws IOException {
if (childTarget >= parentDoc) {
if (childTarget == NO_MORE_DOCS) {
return childDoc = parentDoc = NO_MORE_DOCS;
}
parentDoc = parentIt.advance(childTarget + 1);
validateParentDoc();
if (parentDoc == NO_MORE_DOCS) {
return childDoc = NO_MORE_DOCS;
}
// scan to the first parent that has children
while (true) {
final int firstChild = parentBits.prevSetBit(parentDoc-1) + 1;
if (firstChild != parentDoc) {
// this parent has children
childTarget = Math.max(childTarget, firstChild);
break;
}
// parent with no children, move to the next one
parentDoc = parentIt.nextDoc();
validateParentDoc();
if (parentDoc == NO_MORE_DOCS) {
return childDoc = NO_MORE_DOCS;
}
}
if (doScores) {
parentScore = parentScorer.score();
parentFreq = parentScorer.freq();
}
}
assert childTarget < parentDoc;
assert !parentBits.get(childTarget);
childDoc = childTarget;
//System.out.println(" " + childDoc);
return childDoc;
}
@Override
public long cost() {
return parentIt.cost();
}
};
}
/** Detect mis-use, where provided parent query in fact
* sometimes returns child documents. */
private void validateParentDoc() {
if (parentDoc != DocIdSetIterator.NO_MORE_DOCS && !parentBits.get(parentDoc)) {
throw new IllegalStateException(INVALID_QUERY_MESSAGE + parentDoc);
}
}
@Override
public int docID() {
return childDoc;
}
@Override
public float score() throws IOException {
return parentScore;
}
@Override
public int freq() throws IOException {
return parentFreq;
}
int getParentDoc() {
return parentDoc;
}
}
@Override
public Query rewrite(IndexReader reader) throws IOException {
final Query parentRewrite = parentQuery.rewrite(reader);
if (parentRewrite != parentQuery) {
return new ToChildBlockJoinQuery(parentRewrite, parentsFilter);
} else {
return super.rewrite(reader);
}
}
@Override
public String toString(String field) {
return "ToChildBlockJoinQuery ("+parentQuery.toString()+")";
}
@Override
public boolean equals(Object other) {
return sameClassAs(other) &&
equalsTo(getClass().cast(other));
}
private boolean equalsTo(ToChildBlockJoinQuery other) {
return parentQuery.equals(other.parentQuery) &&
parentsFilter.equals(other.parentsFilter);
}
@Override
public int hashCode() {
final int prime = 31;
int hash = classHash();
hash = prime * hash + parentQuery.hashCode();
hash = prime * hash + parentsFilter.hashCode();
return hash;
}
}