/*
* 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.core.NodeId;
import org.apache.jackrabbit.core.query.LocationStepQueryNode;
import org.apache.jackrabbit.core.query.lucene.hits.AdaptingHits;
import org.apache.jackrabbit.core.query.lucene.hits.Hits;
import org.apache.jackrabbit.core.query.lucene.hits.HitsIntersection;
import org.apache.jackrabbit.core.query.lucene.hits.ScorerHits;
import org.apache.jackrabbit.core.state.ItemStateException;
import org.apache.jackrabbit.core.state.ItemStateManager;
import org.apache.jackrabbit.core.state.NodeState;
import org.apache.jackrabbit.spi.Name;
import org.apache.lucene.document.Document;
import org.apache.lucene.index.IndexReader;
import org.apache.lucene.index.Term;
import org.apache.lucene.index.TermDocs;
import org.apache.lucene.search.Explanation;
import org.apache.lucene.search.HitCollector;
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.TermQuery;
import org.apache.lucene.search.Weight;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import java.util.Set;
/**
* Implements a lucene <code>Query</code> which returns the child nodes of the
* nodes selected by another <code>Query</code>.
*/
class ChildAxisQuery extends Query {
/**
* The item state manager containing persistent item states.
*/
private final ItemStateManager itemMgr;
/**
* The context query
*/
private Query contextQuery;
/**
* The nameTest to apply on the child axis, or <code>null</code> if all
* child nodes should be selected.
*/
private final String nameTest;
/**
* The context position for the selected child node, or
* {@link LocationStepQueryNode#NONE} if no position is specified.
*/
private final int position;
/**
* The scorer of the context query
*/
private Scorer contextScorer;
/**
* The scorer of the name test query
*/
private Scorer nameTestScorer;
/**
* Creates a new <code>ChildAxisQuery</code> based on a <code>context</code>
* query.
*
* @param itemMgr the item state manager.
* @param context the context for this query.
* @param nameTest a name test or <code>null</code> if any child node is
* selected.
*/
ChildAxisQuery(ItemStateManager itemMgr, Query context, String nameTest) {
this(itemMgr, context, nameTest, LocationStepQueryNode.NONE);
}
/**
* Creates a new <code>ChildAxisQuery</code> based on a <code>context</code>
* query.
*
* @param itemMgr the item state manager.
* @param context the context for this query.
* @param nameTest a name test or <code>null</code> if any child node is
* selected.
* @param position the context position of the child node to select. If
* <code>position</code> is {@link LocationStepQueryNode#NONE}, the context
* position of the child node is not checked.
*/
ChildAxisQuery(ItemStateManager itemMgr, Query context, String nameTest, int position) {
this.itemMgr = itemMgr;
this.contextQuery = context;
this.nameTest = nameTest;
this.position = position;
}
/**
* Creates a <code>Weight</code> instance for this query.
*
* @param searcher the <code>Searcher</code> instance to use.
* @return a <code>ChildAxisWeight</code>.
*/
protected Weight createWeight(Searcher searcher) {
return new ChildAxisWeight(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 ChildAxisQuery(itemMgr, cQuery, nameTest, position);
}
}
/**
* Always returns 'ChildAxisQuery'.
*
* @param field the name of a field.
* @return 'ChildAxisQuery'.
*/
public String toString(String field) {
return "ChildAxisQuery";
}
//-------------------< ChildAxisWeight >------------------------------------
/**
* The <code>Weight</code> implementation for this <code>ChildAxisQuery</code>.
*/
private class ChildAxisWeight implements Weight {
/**
* The searcher in use
*/
private final Searcher searcher;
/**
* Creates a new <code>ChildAxisWeight</code> instance using
* <code>searcher</code>.
*
* @param searcher a <code>Searcher</code> instance.
*/
private ChildAxisWeight(Searcher searcher) {
this.searcher = searcher;
}
/**
* Returns this <code>ChildAxisQuery</code>.
*
* @return this <code>ChildAxisQuery</code>.
*/
public Query getQuery() {
return ChildAxisQuery.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>ChildAxisQuery</code>.
*
* @param reader a reader for accessing the index.
* @return a <code>ChildAxisScorer</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);
if (nameTest != null) {
nameTestScorer = new TermQuery(new Term(FieldNames.LABEL, nameTest)).weight(searcher).scorer(reader);
}
return new ChildAxisScorer(searcher.getSimilarity(), reader);
}
/**
* {@inheritDoc}
*/
public Explanation explain(IndexReader reader, int doc) throws IOException {
return new Explanation();
}
}
//----------------------< ChildAxisScorer >---------------------------------
/**
* Implements a <code>Scorer</code> for this <code>ChildAxisQuery</code>.
*/
private class ChildAxisScorer extends Scorer {
/**
* An <code>IndexReader</code> to access the index.
*/
private final IndexReader reader;
/**
* The next document id to return
*/
private int nextDoc = -1;
/**
* A <code>Hits</code> instance containing all hits
*/
private Hits hits;
/**
* Creates a new <code>ChildAxisScorer</code>.
*
* @param similarity the <code>Similarity</code> instance to use.
* @param reader for index access.
*/
protected ChildAxisScorer(Similarity similarity, IndexReader reader) {
super(similarity);
this.reader = reader;
}
/**
* {@inheritDoc}
*/
public boolean next() throws IOException {
calculateChildren();
do {
nextDoc = hits.next();
} while (nextDoc > -1 && !indexIsValid(nextDoc));
return nextDoc > -1;
}
/**
* {@inheritDoc}
*/
public int doc() {
return nextDoc;
}
/**
* {@inheritDoc}
*/
public float score() throws IOException {
return 1.0f;
}
/**
* {@inheritDoc}
*/
public boolean skipTo(int target) throws IOException {
calculateChildren();
nextDoc = hits.skipTo(target);
while (nextDoc > -1 && !indexIsValid(nextDoc))
next();
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 calculateChildren() throws IOException {
if (hits == null) {
// collect all context nodes
List uuids = new ArrayList();
final Hits contextHits = new AdaptingHits();
contextScorer.score(new HitCollector() {
public void collect(int doc, float score) {
contextHits.set(doc);
}
});
// read the uuids of the context nodes
int i = contextHits.next();
while (i > -1) {
String uuid = reader.document(i).get(FieldNames.UUID);
uuids.add(uuid);
i = contextHits.next();
}
// collect all children of the context nodes
Hits childrenHits = new AdaptingHits();
TermDocs docs = reader.termDocs();
try {
for (Iterator it = uuids.iterator(); it.hasNext();) {
docs.seek(new Term(FieldNames.PARENT, (String) it.next()));
while (docs.next()) {
childrenHits.set(docs.doc());
}
}
} finally {
docs.close();
}
if (nameTestScorer != null) {
hits = new HitsIntersection(childrenHits, new ScorerHits(nameTestScorer));
} else {
hits = childrenHits;
}
}
}
private boolean indexIsValid(int i) throws IOException {
if (position != LocationStepQueryNode.NONE) {
Document node = reader.document(i);
NodeId parentId = NodeId.valueOf(node.get(FieldNames.PARENT));
NodeId id = NodeId.valueOf(node.get(FieldNames.UUID));
try {
NodeState state = (NodeState) itemMgr.getItemState(parentId);
if (nameTest == null) {
// only select this node if it is the child at
// specified position
if (position == LocationStepQueryNode.LAST) {
// only select last
List childNodes = state.getChildNodeEntries();
if (childNodes.size() == 0
|| !((NodeState.ChildNodeEntry) childNodes.get(childNodes.size() - 1))
.getId().equals(id)) {
return false;
}
} else {
List childNodes = state.getChildNodeEntries();
if (position < 1
|| childNodes.size() < position
|| !((NodeState.ChildNodeEntry) childNodes.get(position - 1)).getId().equals(id)) {
return false;
}
}
} else {
// select the node when its index is equal to
// specified position
if (position == LocationStepQueryNode.LAST) {
// only select last
NodeState.ChildNodeEntry entry =
state.getChildNodeEntry(id);
if (entry == null) {
// no such child node, probably deleted meanwhile
return false;
} else {
// only use the last one
Name name = entry.getName();
List childNodes = state.getChildNodeEntries(name);
if (childNodes.size() == 0
|| !((NodeState.ChildNodeEntry) childNodes.get(childNodes.size() - 1))
.getId().equals(id)) {
return false;
}
}
} else {
NodeState.ChildNodeEntry entry =
state.getChildNodeEntry(id);
if (entry == null) {
// no such child node, probably has been deleted meanwhile
return false;
} else {
if (entry.getIndex() != position) {
return false;
}
}
}
}
} catch (ItemStateException e) {
// ignore this node, probably has been deleted meanwhile
return false;
}
}
return true;
}
}
}