Java tutorial
/** * 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; } }