/*
* Licensed to Elasticsearch under one or more contributor
* license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright
* ownership. Elasticsearch 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.elasticsearch.common.lucene;
import com.google.common.collect.Iterables;
import org.apache.lucene.analysis.core.KeywordAnalyzer;
import org.apache.lucene.analysis.standard.StandardAnalyzer;
import org.apache.lucene.codecs.CodecUtil;
import org.apache.lucene.codecs.DocValuesFormat;
import org.apache.lucene.codecs.PostingsFormat;
import org.apache.lucene.index.*;
import org.apache.lucene.search.*;
import org.apache.lucene.store.*;
import org.apache.lucene.util.Bits;
import org.apache.lucene.util.BytesRef;
import org.apache.lucene.util.Counter;
import org.apache.lucene.util.Version;
import org.elasticsearch.ElasticsearchException;
import org.elasticsearch.ExceptionsHelper;
import org.elasticsearch.common.Nullable;
import org.elasticsearch.common.Strings;
import org.elasticsearch.common.SuppressForbidden;
import org.elasticsearch.common.io.stream.StreamInput;
import org.elasticsearch.common.io.stream.StreamOutput;
import org.elasticsearch.common.logging.ESLogger;
import org.elasticsearch.index.analysis.AnalyzerScope;
import org.elasticsearch.index.analysis.NamedAnalyzer;
import org.elasticsearch.index.fielddata.IndexFieldData;
import java.io.IOException;
import java.text.ParseException;
import java.util.*;
/**
*
*/
public class Lucene {
// TODO: remove VERSION, and have users use Version.LATEST.
public static final Version VERSION = Version.LATEST;
public static final Version ANALYZER_VERSION = VERSION;
public static final Version QUERYPARSER_VERSION = VERSION;
public static final String LATEST_DOC_VALUES_FORMAT = "Lucene54";
public static final String LATEST_POSTINGS_FORMAT = "Lucene50";
public static final String LATEST_CODEC = "Lucene54";
static {
Deprecated annotation = PostingsFormat.forName(LATEST_POSTINGS_FORMAT).getClass().getAnnotation(Deprecated.class);
assert annotation == null : "PostingsFromat " + LATEST_POSTINGS_FORMAT + " is deprecated" ;
annotation = DocValuesFormat.forName(LATEST_DOC_VALUES_FORMAT).getClass().getAnnotation(Deprecated.class);
assert annotation == null : "DocValuesFormat " + LATEST_DOC_VALUES_FORMAT + " is deprecated" ;
}
public static final NamedAnalyzer STANDARD_ANALYZER = new NamedAnalyzer("_standard", AnalyzerScope.GLOBAL, new StandardAnalyzer());
public static final NamedAnalyzer KEYWORD_ANALYZER = new NamedAnalyzer("_keyword", AnalyzerScope.GLOBAL, new KeywordAnalyzer());
public static final ScoreDoc[] EMPTY_SCORE_DOCS = new ScoreDoc[0];
public static final TopDocs EMPTY_TOP_DOCS = new TopDocs(0, EMPTY_SCORE_DOCS, 0.0f);
@SuppressWarnings("deprecation")
public static Version parseVersion(@Nullable String version, Version defaultVersion, ESLogger logger) {
if (version == null) {
return defaultVersion;
}
try {
return Version.parse(version);
} catch (ParseException e) {
logger.warn("no version match {}, default to {}", e, version, defaultVersion);
return defaultVersion;
}
}
/**
* Reads the segments infos, failing if it fails to load
*/
public static SegmentInfos readSegmentInfos(Directory directory) throws IOException {
return SegmentInfos.readLatestCommit(directory);
}
/**
* Returns an iterable that allows to iterate over all files in this segments info
*/
public static Iterable<String> files(SegmentInfos infos) throws IOException {
final List<Collection<String>> list = new ArrayList<>();
list.add(Collections.singleton(infos.getSegmentsFileName()));
for (SegmentCommitInfo info : infos) {
list.add(info.files());
}
return Iterables.concat(list.toArray(new Collection[0]));
}
/**
* Returns the number of documents in the index referenced by this {@link SegmentInfos}
*/
public static int getNumDocs(SegmentInfos info) {
int numDocs = 0;
for (SegmentCommitInfo si : info) {
numDocs += si.info.maxDoc() - si.getDelCount();
}
return numDocs;
}
/**
* Reads the segments infos from the given commit, failing if it fails to load
*/
public static SegmentInfos readSegmentInfos(IndexCommit commit) throws IOException {
// Using commit.getSegmentsFileName() does NOT work here, have to
// manually create the segment filename
String filename = IndexFileNames.fileNameFromGeneration(IndexFileNames.SEGMENTS, "", commit.getGeneration());
return SegmentInfos.readCommit(commit.getDirectory(), filename);
}
/**
* Reads the segments infos from the given segments file name, failing if it fails to load
*/
private static SegmentInfos readSegmentInfos(String segmentsFileName, Directory directory) throws IOException {
return SegmentInfos.readCommit(directory, segmentsFileName);
}
/**
* This method removes all files from the given directory that are not referenced by the given segments file.
* This method will open an IndexWriter and relies on index file deleter to remove all unreferenced files. Segment files
* that are newer than the given segments file are removed forcefully to prevent problems with IndexWriter opening a potentially
* broken commit point / leftover.
* <b>Note:</b> this method will fail if there is another IndexWriter open on the given directory. This method will also acquire
* a write lock from the directory while pruning unused files. This method expects an existing index in the given directory that has
* the given segments file.
*/
public static SegmentInfos pruneUnreferencedFiles(String segmentsFileName, Directory directory) throws IOException {
final SegmentInfos si = readSegmentInfos(segmentsFileName, directory);
try (Lock writeLock = directory.obtainLock(IndexWriter.WRITE_LOCK_NAME)) {
int foundSegmentFiles = 0;
for (final String file : directory.listAll()) {
/**
* we could also use a deletion policy here but in the case of snapshot and restore
* sometimes we restore an index and override files that were referenced by a "future"
* commit. If such a commit is opened by the IW it would likely throw a corrupted index exception
* since checksums don's match anymore. that's why we prune the name here directly.
* We also want the caller to know if we were not able to remove a segments_N file.
*/
if (file.startsWith(IndexFileNames.SEGMENTS) || file.equals(IndexFileNames.OLD_SEGMENTS_GEN)) {
foundSegmentFiles++;
if (file.equals(si.getSegmentsFileName()) == false) {
directory.deleteFile(file); // remove all segment_N files except of the one we wanna keep
}
}
}
assert SegmentInfos.getLastCommitSegmentsFileName(directory).equals(segmentsFileName);
if (foundSegmentFiles == 0) {
throw new IllegalStateException("no commit found in the directory");
}
}
final CommitPoint cp = new CommitPoint(si, directory);
try (IndexWriter writer = new IndexWriter(directory, new IndexWriterConfig(Lucene.STANDARD_ANALYZER)
.setIndexCommit(cp)
.setCommitOnClose(false)
.setMergePolicy(NoMergePolicy.INSTANCE)
.setOpenMode(IndexWriterConfig.OpenMode.APPEND))) {
// do nothing and close this will kick of IndexFileDeleter which will remove all pending files
}
return si;
}
/**
* This method removes all lucene files from the given directory. It will first try to delete all commit points / segments
* files to ensure broken commits or corrupted indices will not be opened in the future. If any of the segment files can't be deleted
* this operation fails.
*/
public static void cleanLuceneIndex(Directory directory) throws IOException {
try (Lock writeLock = directory.obtainLock(IndexWriter.WRITE_LOCK_NAME)) {
for (final String file : directory.listAll()) {
if (file.startsWith(IndexFileNames.SEGMENTS) || file.equals(IndexFileNames.OLD_SEGMENTS_GEN)) {
directory.deleteFile(file); // remove all segment_N files
}
}
}
try (IndexWriter writer = new IndexWriter(directory, new IndexWriterConfig(Lucene.STANDARD_ANALYZER)
.setMergePolicy(NoMergePolicy.INSTANCE) // no merges
.setCommitOnClose(false) // no commits
.setOpenMode(IndexWriterConfig.OpenMode.CREATE))) // force creation - don't append...
{
// do nothing and close this will kick of IndexFileDeleter which will remove all pending files
}
}
public static void checkSegmentInfoIntegrity(final Directory directory) throws IOException {
new SegmentInfos.FindSegmentsFile(directory) {
@Override
protected Object doBody(String segmentFileName) throws IOException {
try (IndexInput input = directory.openInput(segmentFileName, IOContext.READ)) {
final int format = input.readInt();
final int actualFormat;
if (format == CodecUtil.CODEC_MAGIC) {
// 4.0+
actualFormat = CodecUtil.checkHeaderNoMagic(input, "segments", SegmentInfos.VERSION_40, Integer.MAX_VALUE);
if (actualFormat >= SegmentInfos.VERSION_48) {
CodecUtil.checksumEntireFile(input);
}
}
// legacy....
}
return null;
}
}.run();
}
/**
* Wraps <code>delegate</code> with count based early termination collector with a threshold of <code>maxCountHits</code>
*/
public final static EarlyTerminatingCollector wrapCountBasedEarlyTerminatingCollector(final Collector delegate, int maxCountHits) {
return new EarlyTerminatingCollector(delegate, maxCountHits);
}
/**
* Wraps <code>delegate</code> with a time limited collector with a timeout of <code>timeoutInMillis</code>
*/
public final static TimeLimitingCollector wrapTimeLimitingCollector(final Collector delegate, final Counter counter, long timeoutInMillis) {
return new TimeLimitingCollector(delegate, counter, timeoutInMillis);
}
/**
* Check whether there is one or more documents matching the provided query.
*/
public static boolean exists(IndexSearcher searcher, Query query) throws IOException {
final Weight weight = searcher.createNormalizedWeight(query, false);
// the scorer API should be more efficient at stopping after the first
// match than the bulk scorer API
for (LeafReaderContext context : searcher.getIndexReader().leaves()) {
final Scorer scorer = weight.scorer(context);
if (scorer == null) {
continue;
}
final Bits liveDocs = context.reader().getLiveDocs();
final DocIdSetIterator iterator = scorer.iterator();
for (int doc = iterator.nextDoc(); doc != DocIdSetIterator.NO_MORE_DOCS; doc = iterator.nextDoc()) {
if (liveDocs == null || liveDocs.get(doc)) {
return true;
}
}
}
return false;
}
public static TopDocs readTopDocs(StreamInput in) throws IOException {
if (in.readBoolean()) {
int totalHits = in.readVInt();
float maxScore = in.readFloat();
SortField[] fields = new SortField[in.readVInt()];
for (int i = 0; i < fields.length; i++) {
String field = null;
if (in.readBoolean()) {
field = in.readString();
}
SortField.Type sortType = readSortType(in);
Object missingValue = readMissingValue(in);
boolean reverse = in.readBoolean();
fields[i] = new SortField(field, sortType, reverse);
if (missingValue != null) {
fields[i].setMissingValue(missingValue);
}
}
FieldDoc[] fieldDocs = new FieldDoc[in.readVInt()];
for (int i = 0; i < fieldDocs.length; i++) {
fieldDocs[i] = readFieldDoc(in);
}
return new TopFieldDocs(totalHits, fieldDocs, fields, maxScore);
} else {
int totalHits = in.readVInt();
float maxScore = in.readFloat();
ScoreDoc[] scoreDocs = new ScoreDoc[in.readVInt()];
for (int i = 0; i < scoreDocs.length; i++) {
scoreDocs[i] = new ScoreDoc(in.readVInt(), in.readFloat());
}
return new TopDocs(totalHits, scoreDocs, maxScore);
}
}
public static FieldDoc readFieldDoc(StreamInput in) throws IOException {
Comparable[] cFields = new Comparable[in.readVInt()];
for (int j = 0; j < cFields.length; j++) {
byte type = in.readByte();
if (type == 0) {
cFields[j] = null;
} else if (type == 1) {
cFields[j] = in.readString();
} else if (type == 2) {
cFields[j] = in.readInt();
} else if (type == 3) {
cFields[j] = in.readLong();
} else if (type == 4) {
cFields[j] = in.readFloat();
} else if (type == 5) {
cFields[j] = in.readDouble();
} else if (type == 6) {
cFields[j] = in.readByte();
} else if (type == 7) {
cFields[j] = in.readShort();
} else if (type == 8) {
cFields[j] = in.readBoolean();
} else if (type == 9) {
cFields[j] = in.readBytesRef();
} else {
throw new IOException("Can't match type [" + type + "]");
}
}
return new FieldDoc(in.readVInt(), in.readFloat(), cFields);
}
public static ScoreDoc readScoreDoc(StreamInput in) throws IOException {
return new ScoreDoc(in.readVInt(), in.readFloat());
}
public static void writeTopDocs(StreamOutput out, TopDocs topDocs) throws IOException {
if (topDocs instanceof TopFieldDocs) {
out.writeBoolean(true);
TopFieldDocs topFieldDocs = (TopFieldDocs) topDocs;
out.writeVInt(topDocs.totalHits);
out.writeFloat(topDocs.getMaxScore());
out.writeVInt(topFieldDocs.fields.length);
for (SortField sortField : topFieldDocs.fields) {
if (sortField.getField() == null) {
out.writeBoolean(false);
} else {
out.writeBoolean(true);
out.writeString(sortField.getField());
}
if (sortField.getComparatorSource() != null) {
IndexFieldData.XFieldComparatorSource comparatorSource = (IndexFieldData.XFieldComparatorSource) sortField.getComparatorSource();
writeSortType(out, comparatorSource.reducedType());
writeMissingValue(out, comparatorSource.missingValue(sortField.getReverse()));
} else {
writeSortType(out, sortField.getType());
writeMissingValue(out, sortField.missingValue);
}
out.writeBoolean(sortField.getReverse());
}
out.writeVInt(topDocs.scoreDocs.length);
for (ScoreDoc doc : topFieldDocs.scoreDocs) {
writeFieldDoc(out, (FieldDoc) doc);
}
} else {
out.writeBoolean(false);
out.writeVInt(topDocs.totalHits);
out.writeFloat(topDocs.getMaxScore());
out.writeVInt(topDocs.scoreDocs.length);
for (ScoreDoc doc : topDocs.scoreDocs) {
writeScoreDoc(out, doc);
}
}
}
private static void writeMissingValue(StreamOutput out, Object missingValue) throws IOException {
if (missingValue == SortField.STRING_FIRST) {
out.writeByte((byte) 1);
} else if (missingValue == SortField.STRING_LAST) {
out.writeByte((byte) 2);
} else {
out.writeByte((byte) 0);
out.writeGenericValue(missingValue);
}
}
private static Object readMissingValue(StreamInput in) throws IOException {
final byte id = in.readByte();
switch (id) {
case 0:
return in.readGenericValue();
case 1:
return SortField.STRING_FIRST;
case 2:
return SortField.STRING_LAST;
default:
throw new IOException("Unknown missing value id: " + id);
}
}
public static void writeFieldDoc(StreamOutput out, FieldDoc fieldDoc) throws IOException {
out.writeVInt(fieldDoc.fields.length);
for (Object field : fieldDoc.fields) {
if (field == null) {
out.writeByte((byte) 0);
} else {
Class type = field.getClass();
if (type == String.class) {
out.writeByte((byte) 1);
out.writeString((String) field);
} else if (type == Integer.class) {
out.writeByte((byte) 2);
out.writeInt((Integer) field);
} else if (type == Long.class) {
out.writeByte((byte) 3);
out.writeLong((Long) field);
} else if (type == Float.class) {
out.writeByte((byte) 4);
out.writeFloat((Float) field);
} else if (type == Double.class) {
out.writeByte((byte) 5);
out.writeDouble((Double) field);
} else if (type == Byte.class) {
out.writeByte((byte) 6);
out.writeByte((Byte) field);
} else if (type == Short.class) {
out.writeByte((byte) 7);
out.writeShort((Short) field);
} else if (type == Boolean.class) {
out.writeByte((byte) 8);
out.writeBoolean((Boolean) field);
} else if (type == BytesRef.class) {
out.writeByte((byte) 9);
out.writeBytesRef((BytesRef) field);
} else {
throw new IOException("Can't handle sort field value of type [" + type + "]");
}
}
}
out.writeVInt(fieldDoc.doc);
out.writeFloat(fieldDoc.score);
}
public static void writeScoreDoc(StreamOutput out, ScoreDoc scoreDoc) throws IOException {
if (!scoreDoc.getClass().equals(ScoreDoc.class)) {
throw new IllegalArgumentException("This method can only be used to serialize a ScoreDoc, not a " + scoreDoc.getClass());
}
out.writeVInt(scoreDoc.doc);
out.writeFloat(scoreDoc.score);
}
// LUCENE 4 UPGRADE: We might want to maintain our own ordinal, instead of Lucene's ordinal
public static SortField.Type readSortType(StreamInput in) throws IOException {
return SortField.Type.values()[in.readVInt()];
}
public static void writeSortType(StreamOutput out, SortField.Type sortType) throws IOException {
out.writeVInt(sortType.ordinal());
}
public static Explanation readExplanation(StreamInput in) throws IOException {
boolean match = in.readBoolean();
String description = in.readString();
final Explanation[] subExplanations = new Explanation[in.readVInt()];
for (int i = 0; i < subExplanations.length; ++i) {
subExplanations[i] = readExplanation(in);
}
if (match) {
return Explanation.match(in.readFloat(), description, subExplanations);
} else {
return Explanation.noMatch(description, subExplanations);
}
}
public static void writeExplanation(StreamOutput out, Explanation explanation) throws IOException {
out.writeBoolean(explanation.isMatch());
out.writeString(explanation.getDescription());
Explanation[] subExplanations = explanation.getDetails();
out.writeVInt(subExplanations.length);
for (Explanation subExp : subExplanations) {
writeExplanation(out, subExp);
}
if (explanation.isMatch()) {
out.writeFloat(explanation.getValue());
}
}
/**
* This exception is thrown when {@link org.elasticsearch.common.lucene.Lucene.EarlyTerminatingCollector}
* reaches early termination
* */
public final static class EarlyTerminationException extends ElasticsearchException {
public EarlyTerminationException(String msg) {
super(msg);
}
public EarlyTerminationException(StreamInput in) throws IOException{
super(in);
}
}
/**
* A collector that terminates early by throwing {@link org.elasticsearch.common.lucene.Lucene.EarlyTerminationException}
* when count of matched documents has reached <code>maxCountHits</code>
*/
public final static class EarlyTerminatingCollector extends SimpleCollector {
private final int maxCountHits;
private final Collector delegate;
private int count = 0;
private LeafCollector leafCollector;
EarlyTerminatingCollector(final Collector delegate, int maxCountHits) {
this.maxCountHits = maxCountHits;
this.delegate = Objects.requireNonNull(delegate);
}
public int count() {
return count;
}
public boolean exists() {
return count > 0;
}
@Override
public void setScorer(Scorer scorer) throws IOException {
leafCollector.setScorer(scorer);
}
@Override
public void collect(int doc) throws IOException {
leafCollector.collect(doc);
if (++count >= maxCountHits) {
throw new EarlyTerminationException("early termination [CountBased]");
}
}
@Override
public void doSetNextReader(LeafReaderContext atomicReaderContext) throws IOException {
leafCollector = delegate.getLeafCollector(atomicReaderContext);
}
@Override
public boolean needsScores() {
return delegate.needsScores();
}
}
private Lucene() {
}
public static final boolean indexExists(final Directory directory) throws IOException {
return DirectoryReader.indexExists(directory);
}
/**
* Wait for an index to exist for up to {@code timeLimitMillis}. Returns
* true if the index eventually exists, false if not.
*
* Will retry the directory every second for at least {@code timeLimitMillis}
*/
public static final boolean waitForIndex(final Directory directory, final long timeLimitMillis)
throws IOException {
final long DELAY = 1000;
long waited = 0;
try {
while (true) {
if (waited >= timeLimitMillis) {
break;
}
if (indexExists(directory)) {
return true;
}
Thread.sleep(DELAY);
waited += DELAY;
}
} catch (InterruptedException e) {
Thread.currentThread().interrupt();
return false;
}
// one more try after all retries
return indexExists(directory);
}
/**
* Returns <tt>true</tt> iff the given exception or
* one of it's causes is an instance of {@link CorruptIndexException},
* {@link IndexFormatTooOldException}, or {@link IndexFormatTooNewException} otherwise <tt>false</tt>.
*/
public static boolean isCorruptionException(Throwable t) {
return ExceptionsHelper.unwrapCorruption(t) != null;
}
/**
* Parses the version string lenient and returns the the default value if the given string is null or emtpy
*/
public static Version parseVersionLenient(String toParse, Version defaultValue) {
return LenientParser.parse(toParse, defaultValue);
}
@SuppressForbidden(reason = "Version#parseLeniently() used in a central place")
private static final class LenientParser {
public static Version parse(String toParse, Version defaultValue) {
if (Strings.hasLength(toParse)) {
try {
return Version.parseLeniently(toParse);
} catch (ParseException e) {
// pass to default
}
}
return defaultValue;
}
}
/**
* Return a Scorer that throws an ElasticsearchIllegalStateException
* on all operations with the given message.
*/
public static Scorer illegalScorer(final String message) {
return new Scorer(null) {
@Override
public float score() throws IOException {
throw new IllegalStateException(message);
}
@Override
public int freq() throws IOException {
throw new IllegalStateException(message);
}
@Override
public int docID() {
throw new IllegalStateException(message);
}
@Override
public DocIdSetIterator iterator() {
throw new IllegalStateException(message);
}
};
}
private static final class CommitPoint extends IndexCommit {
private String segmentsFileName;
private final Collection<String> files;
private final Directory dir;
private final long generation;
private final Map<String,String> userData;
private final int segmentCount;
private CommitPoint(SegmentInfos infos, Directory dir) throws IOException {
segmentsFileName = infos.getSegmentsFileName();
this.dir = dir;
userData = infos.getUserData();
files = Collections.unmodifiableCollection(infos.files(dir, true));
generation = infos.getGeneration();
segmentCount = infos.size();
}
@Override
public String toString() {
return "DirectoryReader.ReaderCommit(" + segmentsFileName + ")";
}
@Override
public int getSegmentCount() {
return segmentCount;
}
@Override
public String getSegmentsFileName() {
return segmentsFileName;
}
@Override
public Collection<String> getFileNames() {
return files;
}
@Override
public Directory getDirectory() {
return dir;
}
@Override
public long getGeneration() {
return generation;
}
@Override
public boolean isDeleted() {
return false;
}
@Override
public Map<String,String> getUserData() {
return userData;
}
@Override
public void delete() {
throw new UnsupportedOperationException("This IndexCommit does not support deletions");
}
}
/**
* Is it an empty {@link DocIdSet}?
*/
public static boolean isEmpty(@Nullable DocIdSet set) {
return set == null || set == DocIdSet.EMPTY;
}
/**
* Given a {@link Scorer}, return a {@link Bits} instance that will match
* all documents contained in the set. Note that the returned {@link Bits}
* instance MUST be consumed in order.
*/
public static Bits asSequentialAccessBits(final int maxDoc, @Nullable Scorer scorer) throws IOException {
if (scorer == null) {
return new Bits.MatchNoBits(maxDoc);
}
final TwoPhaseIterator twoPhase = scorer.twoPhaseIterator();
final DocIdSetIterator iterator;
if (twoPhase == null) {
iterator = scorer.iterator();
} else {
iterator = twoPhase.approximation();
}
return new Bits() {
int previous = -1;
boolean previousMatched = false;
@Override
public boolean get(int index) {
if (index < 0 || index >= maxDoc) {
throw new IndexOutOfBoundsException(index + " is out of bounds: [" + 0 + "-" + maxDoc + "[");
}
if (index < previous) {
throw new IllegalArgumentException("This Bits instance can only be consumed in order. "
+ "Got called on [" + index + "] while previously called on [" + previous + "]");
}
if (index == previous) {
// we cache whether it matched because it is illegal to call
// twoPhase.matches() twice
return previousMatched;
}
previous = index;
int doc = iterator.docID();
if (doc < index) {
try {
doc = iterator.advance(index);
} catch (IOException e) {
throw new IllegalStateException("Cannot advance iterator", e);
}
}
if (index == doc) {
try {
return previousMatched = twoPhase == null || twoPhase.matches();
} catch (IOException e) {
throw new IllegalStateException("Cannot validate match", e);
}
}
return previousMatched = false;
}
@Override
public int length() {
return maxDoc;
}
};
}
}