/**
* Copyright 2014 National University of Ireland, Galway.
*
* This file is part of the SIREn project. Project and contact information:
*
* https://github.com/rdelbru/SIREn
*
* Licensed 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.sindice.siren.search.node;
import java.io.IOException;
import java.util.Set;
import org.apache.commons.lang.StringUtils;
import org.apache.lucene.index.AtomicReader;
import org.apache.lucene.index.AtomicReaderContext;
import org.apache.lucene.index.DocsAndPositionsEnum;
import org.apache.lucene.index.IndexReaderContext;
import org.apache.lucene.index.ReaderUtil;
import org.apache.lucene.index.Term;
import org.apache.lucene.index.TermContext;
import org.apache.lucene.index.TermState;
import org.apache.lucene.index.TermsEnum;
import org.apache.lucene.search.ComplexExplanation;
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.search.similarities.Similarity;
import org.apache.lucene.search.similarities.Similarity.ExactSimScorer;
import org.apache.lucene.util.Bits;
import org.apache.lucene.util.ToStringUtils;
import org.sindice.siren.index.DocsNodesAndPositionsEnum;
/**
* A {@link NodePrimitiveQuery} that matches nodes containing a term.
*
* <p>
*
* Provides an interface to iterate over the candidate documents and nodes
* containing the term. This may be combined with other terms with a
* {@link NodeBooleanQuery}.
*/
public class NodeTermQuery extends NodePrimitiveQuery {
private final Term term;
private final int docFreq;
private final TermContext perReaderTermState;
protected class NodeTermWeight extends Weight {
private final Similarity similarity;
private final Similarity.SimWeight stats;
private final TermContext termStates;
public NodeTermWeight(final IndexSearcher searcher, final TermContext termStates)
throws IOException {
assert termStates != null : "TermContext must not be null";
this.termStates = termStates;
this.similarity = searcher.getSimilarity();
this.stats = similarity.computeWeight(
NodeTermQuery.this.getBoost(),
searcher.collectionStatistics(term.field()),
searcher.termStatistics(term, termStates));
}
@Override
public String toString() {
return "weight(" + NodeTermQuery.this + ")";
}
@Override
public Query getQuery() {
return NodeTermQuery.this;
}
@Override
public float getValueForNormalization() throws IOException {
return stats.getValueForNormalization();
}
@Override
public void normalize(final float queryNorm, final float topLevelBoost) {
stats.normalize(queryNorm, topLevelBoost);
}
@Override
public Scorer scorer(final AtomicReaderContext context,
final boolean scoreDocsInOrder,
final boolean topScorer, final Bits acceptDocs)
throws IOException {
assert termStates.topReaderContext == ReaderUtil.getTopLevelContext(context) : "The top-reader used to create Weight (" + termStates.topReaderContext + ") is not the same as the current reader's top-reader (" + ReaderUtil.getTopLevelContext(context);
final TermsEnum termsEnum = this.getTermsEnum(context);
if (termsEnum == null) {
return null;
}
final DocsAndPositionsEnum docsEnum = termsEnum.docsAndPositions(acceptDocs, null);
final DocsNodesAndPositionsEnum sirenDocsEnum = NodeTermQuery.this.getDocsNodesAndPositionsEnum(docsEnum);
return new NodeTermScorer(this, sirenDocsEnum, this.createDocScorer(context));
}
/**
* Creates an {@link ExactDocScorer} for this {@link TermWeight}
**/
ExactSimScorer createDocScorer(final AtomicReaderContext context)
throws IOException {
return similarity.exactSimScorer(stats, context);
}
/**
* Returns a {@link TermsEnum} positioned at this weights Term or null if
* the term does not exist in the given context
*/
TermsEnum getTermsEnum(final AtomicReaderContext context) throws IOException {
final TermState state = termStates.get(context.ord);
if (state == null) { // term is not present in that reader
assert this.termNotInReader(context.reader(), term) : "no termstate found but term exists in reader term=" + term;
return null;
}
//System.out.println("LD=" + reader.getLiveDocs() + " set?=" + (reader.getLiveDocs() != null ? reader.getLiveDocs().get(0) : "null"));
final TermsEnum termsEnum = context.reader().terms(term.field()).iterator(null);
termsEnum.seekExact(term.bytes(), state);
return termsEnum;
}
private boolean termNotInReader(final AtomicReader reader, final Term term) throws IOException {
// only called from assert
//System.out.println("TQ.termNotInReader reader=" + reader + " term=" + field + ":" + bytes.utf8ToString());
return reader.docFreq(term) == 0;
}
@Override
public Explanation explain(final AtomicReaderContext context, final int doc) throws IOException {
final NodeScorer scorer = (NodeScorer) this.scorer(context, true, false, context.reader().getLiveDocs());
if (scorer != null) {
if (scorer.skipToCandidate(doc) && scorer.doc() == doc) {
final ExactSimScorer docScorer = similarity.exactSimScorer(stats, context);
final ComplexExplanation result = new ComplexExplanation();
result.setDescription("weight("+this.getQuery()+" in "+doc+") [" + similarity.getClass().getSimpleName() + "], result of:");
while (scorer.nextNode()) {
final ComplexExplanation nodeMatch = new ComplexExplanation();
nodeMatch.setDescription("in "+scorer.node()+"), result of:");
final float freq = scorer.freqInNode();
final Explanation scoreExplanation = docScorer.explain(doc, new Explanation(freq, "termFreq=" + freq));
nodeMatch.setValue(scoreExplanation.getValue());
nodeMatch.setMatch(true);
nodeMatch.addDetail(scoreExplanation);
result.addDetail(nodeMatch);
}
result.setMatch(true);
return result;
}
}
return new ComplexExplanation(false, 0.0f, "no matching term");
}
}
/** Constructs a query for the term <code>t</code>. */
public NodeTermQuery(final Term t) {
this(t, -1);
}
/** Expert: constructs a TermQuery that will use the
* provided docFreq instead of looking up the docFreq
* against the searcher. */
public NodeTermQuery(final Term t, final int docFreq) {
term = t;
this.docFreq = docFreq;
perReaderTermState = null;
}
/** Expert: constructs a TermQuery that will use the
* provided docFreq instead of looking up the docFreq
* against the searcher. */
public NodeTermQuery(final Term t, final TermContext states) {
assert states != null;
term = t;
docFreq = states.docFreq();
perReaderTermState = states;
}
/** Returns the term of this query. */
public Term getTerm() {
return term;
}
@Override
public Weight createWeight(final IndexSearcher searcher) throws IOException {
final IndexReaderContext context = searcher.getTopReaderContext();
final TermContext termState;
if (perReaderTermState == null || perReaderTermState.topReaderContext != context) {
// make TermQuery single-pass if we don't have a PRTS or if the context differs!
termState = TermContext.build(context, term, true); // cache term lookups!
} else {
// PRTS was pre-build for this IS
termState = this.perReaderTermState;
}
// we must not ignore the given docFreq - if set use the given value (lie)
if (docFreq != -1)
termState.setDocFreq(docFreq);
return new NodeTermWeight(searcher, termState);
}
@Override
public void extractTerms(final Set<Term> terms) {
terms.add(this.getTerm());
}
/**
* Prints a user-readable version of this query.
* <p>
* The term is wrapped in simple quotes, so that any special characters it
* may contains are disabled. See ProtectedQueryNode in siren-qparser.
*/
@Override
public String toString(final String field) {
final StringBuffer buffer = new StringBuffer();
final CharSequence text = term.text();
if (text.length() != 0) {
buffer.append("'").append(text).append("'");
}
buffer.append(ToStringUtils.boost(this.getBoost()));
return this.wrapToStringWithDatatype(buffer).toString();
}
/** Returns true iff <code>o</code> is equal to this. */
@Override
public boolean equals(final Object o) {
if (!(o instanceof NodeTermQuery)) return false;
final NodeTermQuery other = (NodeTermQuery) o;
return (this.getBoost() == other.getBoost()) &&
this.term.equals(other.term) &&
this.levelConstraint == other.levelConstraint &&
this.lowerBound == other.lowerBound &&
this.upperBound == other.upperBound &&
StringUtils.equals(this.datatype, other.datatype);
}
/** Returns a hash code value for this object. */
@Override
public int hashCode() {
return Float.floatToIntBits(this.getBoost())
^ term.hashCode()
^ levelConstraint
^ upperBound
^ lowerBound;
}
}