/*
* 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.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.apache.lucene.search.Query;
import org.apache.lucene.index.IndexReader;
import org.apache.lucene.index.Term;
import org.apache.lucene.index.TermDocs;
import org.apache.lucene.index.TermFreqVector;
import org.apache.lucene.index.TermPositionVector;
import org.apache.lucene.index.TermVectorOffsetInfo;
import org.apache.lucene.document.Document;
import org.apache.lucene.document.Fieldable;
import org.apache.lucene.analysis.TokenStream;
import org.apache.lucene.analysis.Token;
import org.apache.jackrabbit.core.id.NodeId;
import java.io.IOException;
import java.io.StringReader;
import java.io.Reader;
import java.util.Set;
import java.util.HashSet;
import java.util.TreeMap;
import java.util.SortedMap;
import java.util.Arrays;
/**
* <code>AbstractExcerpt</code> implements base functionality for an excerpt
* provider.
*/
public abstract class AbstractExcerpt implements HighlightingExcerptProvider {
/**
* Logger instance for this class.
*/
private static final Logger log = LoggerFactory.getLogger(AbstractExcerpt.class);
/**
* The search index.
*/
protected SearchIndex index;
/**
* The current query.
*/
protected Query query;
/**
* Indicates whether the query is already rewritten.
*/
private boolean rewritten = false;
/**
* {@inheritDoc}
*/
public void init(Query query, SearchIndex index) throws IOException {
this.index = index;
this.query = query;
}
/**
* {@inheritDoc}
*/
public String getExcerpt(NodeId id, int maxFragments, int maxFragmentSize)
throws IOException {
IndexReader reader = index.getIndexReader();
try {
checkRewritten(reader);
Term idTerm = TermFactory.createUUIDTerm(id.toString());
TermDocs tDocs = reader.termDocs(idTerm);
int docNumber;
Document doc;
try {
if (tDocs.next()) {
docNumber = tDocs.doc();
doc = reader.document(docNumber);
} else {
// node not found in index
return null;
}
} finally {
tDocs.close();
}
Fieldable[] fields = doc.getFieldables(FieldNames.FULLTEXT);
if (fields.length == 0) {
log.debug("Fulltext field not stored, using {}",
SimpleExcerptProvider.class.getName());
SimpleExcerptProvider exProvider = new SimpleExcerptProvider();
exProvider.init(query, index);
return exProvider.getExcerpt(id, maxFragments, maxFragmentSize);
}
StringBuffer text = new StringBuffer();
String separator = "";
for (int i = 0; i < fields.length; i++) {
if (fields[i].stringValue().length() == 0) {
continue;
}
text.append(separator);
text.append(fields[i].stringValue());
// this is a hack! in general multiple fields with the same
// name are handled properly, that is, offset and position is
// calculated correctly. there is one case however where
// the offset gets wrong:
// if a term text ends with characters that are considered noise
// then the offset of the next field will be off by the number
// of noise characters.
// therefore we delete noise characters at the end of the text.
// this process is required for all but the last field
if (i < fields.length - 1) {
for (int j = text.length() - 1; j >= 0; j--) {
if (Character.isLetterOrDigit(text.charAt(j))) {
break;
} else {
text.deleteCharAt(j);
}
}
}
separator = " ";
}
TermFreqVector tfv = reader.getTermFreqVector(
docNumber, FieldNames.FULLTEXT);
if (tfv instanceof TermPositionVector) {
return createExcerpt((TermPositionVector) tfv, text.toString(),
maxFragments, maxFragmentSize);
} else {
log.debug("No TermPositionVector on Fulltext field.");
return null;
}
} finally {
Util.closeOrRelease(reader);
}
}
/**
* {@inheritDoc}
*/
public String highlight(String text) throws IOException {
checkRewritten(null);
return createExcerpt(createTermPositionVector(text),
text, 1, (text.length() + 1) * 2);
}
/**
* Creates an excerpt for the given <code>text</code> using token offset
* information provided by <code>tpv</code>.
*
* @param tpv the term position vector for the fulltext field.
* @param text the original text.
* @param maxFragments the maximum number of fragments to create.
* @param maxFragmentSize the maximum number of characters in a fragment.
* @return the xml excerpt.
* @throws IOException if an error occurs while creating the excerpt.
*/
protected abstract String createExcerpt(TermPositionVector tpv,
String text,
int maxFragments,
int maxFragmentSize)
throws IOException;
/**
* @return the extracted terms from the query.
*/
protected final Set<Term> getQueryTerms() {
Set<Term> extractedTerms = new HashSet<Term>();
Set<Term> relevantTerms = new HashSet<Term>();
query.extractTerms(extractedTerms);
// only keep terms for fulltext fields
for (Term t : extractedTerms) {
if (t.field().equals(FieldNames.FULLTEXT)) {
relevantTerms.add(t);
} else {
int idx = t.field().indexOf(FieldNames.FULLTEXT_PREFIX);
if (idx != -1) {
relevantTerms.add(new Term(FieldNames.FULLTEXT, t.text()));
}
}
}
return relevantTerms;
}
/**
* Makes sure the {@link #query} is rewritten. If the query is already
* rewritten, this method returns immediately.
*
* @param reader an optional index reader, if none is passed this method
* will retrieve one from the {@link #index} and close it
* again after the rewrite operation.
* @throws IOException if an error occurs while the query is rewritten.
*/
private void checkRewritten(IndexReader reader) throws IOException {
if (!rewritten) {
IndexReader r = reader;
if (r == null) {
r = index.getIndexReader();
}
try {
query = query.rewrite(r);
} finally {
// only close reader if this method opened one
if (reader == null) {
Util.closeOrRelease(r);
}
}
rewritten = true;
}
}
/**
* @param text the text.
* @return a <code>TermPositionVector</code> for the given text.
*/
private TermPositionVector createTermPositionVector(String text) {
// term -> TermVectorOffsetInfo[]
final SortedMap<String, TermVectorOffsetInfo[]> termMap =
new TreeMap<String, TermVectorOffsetInfo[]>();
Reader r = new StringReader(text);
TokenStream ts = index.getTextAnalyzer().tokenStream("", r);
Token t = new Token();
try {
while ((t = ts.next(t)) != null) {
String termText = t.term();
TermVectorOffsetInfo[] info = termMap.get(termText);
if (info == null) {
info = new TermVectorOffsetInfo[1];
} else {
TermVectorOffsetInfo[] tmp = info;
info = new TermVectorOffsetInfo[tmp.length + 1];
System.arraycopy(tmp, 0, info, 0, tmp.length);
}
info[info.length - 1] = new TermVectorOffsetInfo(
t.startOffset(), t.endOffset());
termMap.put(termText, info);
}
} catch (IOException e) {
// should never happen, we are reading from a string
}
return new TermPositionVector() {
private String[] terms =
(String[]) termMap.keySet().toArray(new String[termMap.size()]);
public int[] getTermPositions(int index) {
return null;
}
public TermVectorOffsetInfo[] getOffsets(int index) {
TermVectorOffsetInfo[] info = TermVectorOffsetInfo.EMPTY_OFFSET_INFO;
if (index >= 0 && index < terms.length) {
info = termMap.get(terms[index]);
}
return info;
}
public String getField() {
return "";
}
public int size() {
return terms.length;
}
public String[] getTerms() {
return terms;
}
public int[] getTermFrequencies() {
int[] freqs = new int[terms.length];
for (int i = 0; i < terms.length; i++) {
freqs[i] = termMap.get(terms[i]).length;
}
return freqs;
}
public int indexOf(String term) {
int res = Arrays.binarySearch(terms, term);
return res >= 0 ? res : -1;
}
public int[] indexesOf(String[] terms, int start, int len) {
int[] res = new int[len];
for (int i = 0; i < len; i++) {
res[i] = indexOf(terms[i]);
}
return res;
}
};
}
}