/*
* 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.lucene.search.postingshighlight;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Comparator;
import java.util.List;
import org.apache.lucene.analysis.TokenStream;
import org.apache.lucene.analysis.tokenattributes.CharTermAttribute;
import org.apache.lucene.analysis.tokenattributes.OffsetAttribute;
import org.apache.lucene.index.PostingsEnum;
import org.apache.lucene.index.Term;
import org.apache.lucene.search.AutomatonQuery;
import org.apache.lucene.search.BooleanClause;
import org.apache.lucene.search.BooleanQuery;
import org.apache.lucene.search.ConstantScoreQuery;
import org.apache.lucene.search.DisjunctionMaxQuery;
import org.apache.lucene.search.FuzzyQuery;
import org.apache.lucene.search.PrefixQuery;
import org.apache.lucene.search.Query;
import org.apache.lucene.search.TermRangeQuery;
import org.apache.lucene.search.spans.SpanMultiTermQueryWrapper;
import org.apache.lucene.search.spans.SpanNearQuery;
import org.apache.lucene.search.spans.SpanNotQuery;
import org.apache.lucene.search.spans.SpanOrQuery;
import org.apache.lucene.search.spans.SpanPositionCheckQuery;
import org.apache.lucene.util.BytesRef;
import org.apache.lucene.util.CharsRef;
import org.apache.lucene.util.UnicodeUtil;
import org.apache.lucene.util.automaton.Automata;
import org.apache.lucene.util.automaton.Automaton;
import org.apache.lucene.util.automaton.CharacterRunAutomaton;
import org.apache.lucene.util.automaton.LevenshteinAutomata;
import org.apache.lucene.util.automaton.Operations;
/**
* Support for highlighting multiterm queries in PostingsHighlighter.
*/
class MultiTermHighlighting {
/**
* Extracts all MultiTermQueries for {@code field}, and returns equivalent
* automata that will match terms.
*/
static CharacterRunAutomaton[] extractAutomata(Query query, String field) {
List<CharacterRunAutomaton> list = new ArrayList<>();
if (query instanceof BooleanQuery) {
for (BooleanClause clause : (BooleanQuery) query) {
if (!clause.isProhibited()) {
list.addAll(Arrays.asList(extractAutomata(clause.getQuery(), field)));
}
}
} else if (query instanceof ConstantScoreQuery) {
list.addAll(Arrays.asList(extractAutomata(((ConstantScoreQuery) query).getQuery(), field)));
} else if (query instanceof DisjunctionMaxQuery) {
for (Query sub : ((DisjunctionMaxQuery) query).getDisjuncts()) {
list.addAll(Arrays.asList(extractAutomata(sub, field)));
}
} else if (query instanceof SpanOrQuery) {
for (Query sub : ((SpanOrQuery) query).getClauses()) {
list.addAll(Arrays.asList(extractAutomata(sub, field)));
}
} else if (query instanceof SpanNearQuery) {
for (Query sub : ((SpanNearQuery) query).getClauses()) {
list.addAll(Arrays.asList(extractAutomata(sub, field)));
}
} else if (query instanceof SpanNotQuery) {
list.addAll(Arrays.asList(extractAutomata(((SpanNotQuery) query).getInclude(), field)));
} else if (query instanceof SpanPositionCheckQuery) {
list.addAll(Arrays.asList(extractAutomata(((SpanPositionCheckQuery) query).getMatch(), field)));
} else if (query instanceof SpanMultiTermQueryWrapper) {
list.addAll(Arrays.asList(extractAutomata(((SpanMultiTermQueryWrapper<?>) query).getWrappedQuery(), field)));
} else if (query instanceof PrefixQuery) {
final PrefixQuery pq = (PrefixQuery) query;
Term prefix = pq.getPrefix();
if (prefix.field().equals(field)) {
list.add(new CharacterRunAutomaton(Operations.concatenate(Automata.makeString(prefix.text()),
Automata.makeAnyString())) {
@Override
public String toString() {
return pq.toString();
}
});
}
} else if (query instanceof FuzzyQuery) {
final FuzzyQuery fq = (FuzzyQuery) query;
if (fq.getField().equals(field)) {
String utf16 = fq.getTerm().text();
int termText[] = new int[utf16.codePointCount(0, utf16.length())];
for (int cp, i = 0, j = 0; i < utf16.length(); i += Character.charCount(cp)) {
termText[j++] = cp = utf16.codePointAt(i);
}
int termLength = termText.length;
int prefixLength = Math.min(fq.getPrefixLength(), termLength);
String suffix = UnicodeUtil.newString(termText, prefixLength, termText.length - prefixLength);
LevenshteinAutomata builder = new LevenshteinAutomata(suffix, fq.getTranspositions());
String prefix = UnicodeUtil.newString(termText, 0, prefixLength);
Automaton automaton = builder.toAutomaton(fq.getMaxEdits(), prefix);
list.add(new CharacterRunAutomaton(automaton) {
@Override
public String toString() {
return fq.toString();
}
});
}
} else if (query instanceof TermRangeQuery) {
final TermRangeQuery tq = (TermRangeQuery) query;
if (tq.getField().equals(field)) {
final CharsRef lowerBound;
if (tq.getLowerTerm() == null) {
lowerBound = null;
} else {
lowerBound = new CharsRef(tq.getLowerTerm().utf8ToString());
}
final CharsRef upperBound;
if (tq.getUpperTerm() == null) {
upperBound = null;
} else {
upperBound = new CharsRef(tq.getUpperTerm().utf8ToString());
}
final boolean includeLower = tq.includesLower();
final boolean includeUpper = tq.includesUpper();
final CharsRef scratch = new CharsRef();
final Comparator<CharsRef> comparator = CharsRef.getUTF16SortedAsUTF8Comparator();
// this is *not* an automaton, but it's very simple
list.add(new CharacterRunAutomaton(Automata.makeEmpty()) {
@Override
public boolean run(char[] s, int offset, int length) {
scratch.chars = s;
scratch.offset = offset;
scratch.length = length;
if (lowerBound != null) {
int cmp = comparator.compare(scratch, lowerBound);
if (cmp < 0 || (!includeLower && cmp == 0)) {
return false;
}
}
if (upperBound != null) {
int cmp = comparator.compare(scratch, upperBound);
if (cmp > 0 || (!includeUpper && cmp == 0)) {
return false;
}
}
return true;
}
@Override
public String toString() {
return tq.toString();
}
});
}
} else if (query instanceof AutomatonQuery) {
final AutomatonQuery aq = (AutomatonQuery) query;
if (aq.getField().equals(field)) {
list.add(new CharacterRunAutomaton(aq.getAutomaton()) {
@Override
public String toString() {
return aq.toString();
}
});
}
}
return list.toArray(new CharacterRunAutomaton[list.size()]);
}
/**
* Returns a "fake" DocsAndPositionsEnum over the tokenstream, returning offsets where {@code matchers}
* matches tokens.
* <p>
* This is solely used internally by PostingsHighlighter: <b>DO NOT USE THIS METHOD!</b>
*/
static PostingsEnum getDocsEnum(final TokenStream ts, final CharacterRunAutomaton[] matchers) throws IOException {
final CharTermAttribute charTermAtt = ts.addAttribute(CharTermAttribute.class);
final OffsetAttribute offsetAtt = ts.addAttribute(OffsetAttribute.class);
ts.reset();
// TODO: we could use CachingWrapperFilter, (or consume twice) to allow us to have a true freq()
// but this would have a performance cost for likely little gain in the user experience, it
// would only serve to make this method less bogus.
// instead, we always return freq() = Integer.MAX_VALUE and let PH terminate based on offset...
return new PostingsEnum() {
int currentDoc = -1;
int currentMatch = -1;
int currentStartOffset = -1;
int currentEndOffset = -1;
TokenStream stream = ts;
final BytesRef matchDescriptions[] = new BytesRef[matchers.length];
@Override
public int nextPosition() throws IOException {
if (stream != null) {
while (stream.incrementToken()) {
for (int i = 0; i < matchers.length; i++) {
if (matchers[i].run(charTermAtt.buffer(), 0, charTermAtt.length())) {
currentStartOffset = offsetAtt.startOffset();
currentEndOffset = offsetAtt.endOffset();
currentMatch = i;
return 0;
}
}
}
stream.end();
stream.close();
stream = null;
}
// exhausted
currentStartOffset = currentEndOffset = Integer.MAX_VALUE;
return Integer.MAX_VALUE;
}
@Override
public int freq() throws IOException {
return Integer.MAX_VALUE; // lie
}
@Override
public int startOffset() throws IOException {
assert currentStartOffset >= 0;
return currentStartOffset;
}
@Override
public int endOffset() throws IOException {
assert currentEndOffset >= 0;
return currentEndOffset;
}
@Override
public BytesRef getPayload() throws IOException {
if (matchDescriptions[currentMatch] == null) {
matchDescriptions[currentMatch] = new BytesRef(matchers[currentMatch].toString());
}
return matchDescriptions[currentMatch];
}
@Override
public int docID() {
return currentDoc;
}
@Override
public int nextDoc() throws IOException {
throw new UnsupportedOperationException();
}
@Override
public int advance(int target) throws IOException {
return currentDoc = target;
}
@Override
public long cost() {
return 0;
}
};
}
}