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/*
* 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.search;
import com.carrotsearch.hppc.ObjectHashSet;
import org.apache.lucene.index.IndexReader;
import org.apache.lucene.index.LeafReaderContext;
import org.apache.lucene.index.Term;
import org.apache.lucene.index.Terms;
import org.apache.lucene.index.TermsEnum;
import org.apache.lucene.search.BooleanClause;
import org.apache.lucene.search.BooleanQuery;
import org.apache.lucene.search.MatchNoDocsQuery;
import org.apache.lucene.search.MultiPhraseQuery;
import org.apache.lucene.search.Query;
import org.apache.lucene.util.BytesRef;
import org.apache.lucene.util.StringHelper;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Iterator;
import java.util.List;
import java.util.ListIterator;
import java.util.Objects;
public class MultiPhrasePrefixQuery extends Query {
private final String field;
private ArrayList termArrays = new ArrayList<>();
private ArrayList positions = new ArrayList<>();
private int maxExpansions = Integer.MAX_VALUE;
private int slop = 0;
public MultiPhrasePrefixQuery(String field) {
this.field = Objects.requireNonNull(field);
}
/**
* Sets the phrase slop for this query.
*
* @see org.apache.lucene.search.PhraseQuery.Builder#setSlop(int)
*/
public void setSlop(int s) {
slop = s;
}
public void setMaxExpansions(int maxExpansions) {
this.maxExpansions = maxExpansions;
}
/**
* Sets the phrase slop for this query.
*
* @see org.apache.lucene.search.PhraseQuery.Builder#getSlop()
*/
public int getSlop() {
return slop;
}
/**
* Add a single term at the next position in the phrase.
*
* @see org.apache.lucene.search.PhraseQuery.Builder#add(Term)
*/
public void add(Term term) {
add(new Term[]{term});
}
/**
* Add multiple terms at the next position in the phrase. Any of the terms
* may match.
*
* @see org.apache.lucene.search.PhraseQuery.Builder#add(Term)
*/
public void add(Term[] terms) {
int position = 0;
if (positions.size() > 0)
position = positions.get(positions.size() - 1) + 1;
add(terms, position);
}
/**
* Allows to specify the relative position of terms within the phrase.
*
* @param terms the terms
* @param position the position of the terms provided as argument
* @see org.apache.lucene.search.PhraseQuery.Builder#add(Term, int)
*/
public void add(Term[] terms, int position) {
for (int i = 0; i < terms.length; i++) {
if (terms[i].field() != field) {
throw new IllegalArgumentException(
"All phrase terms must be in the same field (" + field + "): "
+ terms[i]);
}
}
termArrays.add(terms);
positions.add(position);
}
/**
* Returns the terms for each position in this phrase
*/
public Term[][] getTerms() {
Term[][] terms = new Term[termArrays.size()][];
for (int i = 0; i < termArrays.size(); i++) {
terms[i] = new Term[termArrays.get(i).length];
System.arraycopy(termArrays.get(i), 0, terms[i], 0, termArrays.get(i).length);
}
return terms;
}
/**
* Returns the relative positions of terms in this phrase.
*/
public int[] getPositions() {
int[] result = new int[positions.size()];
for (int i = 0; i < positions.size(); i++)
result[i] = positions.get(i);
return result;
}
@Override
public Query rewrite(IndexReader reader) throws IOException {
Query rewritten = super.rewrite(reader);
if (rewritten != this) {
return rewritten;
}
if (termArrays.isEmpty()) {
return new MatchNoDocsQuery();
}
MultiPhraseQuery.Builder query = new MultiPhraseQuery.Builder();
query.setSlop(slop);
int sizeMinus1 = termArrays.size() - 1;
for (int i = 0; i < sizeMinus1; i++) {
query.add(termArrays.get(i), positions.get(i));
}
Term[] suffixTerms = termArrays.get(sizeMinus1);
int position = positions.get(sizeMinus1);
ObjectHashSet terms = new ObjectHashSet<>();
for (Term term : suffixTerms) {
getPrefixTerms(terms, term, reader);
if (terms.size() > maxExpansions) {
break;
}
}
if (terms.isEmpty()) {
if (sizeMinus1 == 0) {
// no prefix and the phrase query is empty
return Queries.newMatchNoDocsQuery("No terms supplied for " + MultiPhrasePrefixQuery.class.getName());
}
// if the terms does not exist we could return a MatchNoDocsQuery but this would break the unified highlighter
// which rewrites query with an empty reader.
return new BooleanQuery.Builder()
.add(query.build(), BooleanClause.Occur.MUST)
.add(Queries.newMatchNoDocsQuery("No terms supplied for " + MultiPhrasePrefixQuery.class.getName()),
BooleanClause.Occur.MUST).build();
}
query.add(terms.toArray(Term.class), position);
return query.build();
}
private void getPrefixTerms(ObjectHashSet terms, final Term prefix, final IndexReader reader) throws IOException {
// SlowCompositeReaderWrapper could be used... but this would merge all terms from each segment into one terms
// instance, which is very expensive. Therefore I think it is better to iterate over each leaf individually.
List leaves = reader.leaves();
for (LeafReaderContext leaf : leaves) {
Terms _terms = leaf.reader().terms(field);
if (_terms == null) {
continue;
}
TermsEnum termsEnum = _terms.iterator();
TermsEnum.SeekStatus seekStatus = termsEnum.seekCeil(prefix.bytes());
if (TermsEnum.SeekStatus.END == seekStatus) {
continue;
}
for (BytesRef term = termsEnum.term(); term != null; term = termsEnum.next()) {
if (!StringHelper.startsWith(term, prefix.bytes())) {
break;
}
terms.add(new Term(field, BytesRef.deepCopyOf(term)));
if (terms.size() >= maxExpansions) {
return;
}
}
}
}
@Override
public final String toString(String f) {
StringBuilder buffer = new StringBuilder();
if (field.equals(f) == false) {
buffer.append(field);
buffer.append(":");
}
buffer.append("\"");
Iterator i = termArrays.iterator();
while (i.hasNext()) {
Term[] terms = i.next();
if (terms.length > 1) {
buffer.append("(");
for (int j = 0; j < terms.length; j++) {
buffer.append(terms[j].text());
if (j < terms.length - 1) {
if (i.hasNext()) {
buffer.append(" ");
} else {
buffer.append("* ");
}
}
}
if (i.hasNext()) {
buffer.append(") ");
} else {
buffer.append("*)");
}
} else {
buffer.append(terms[0].text());
if (i.hasNext()) {
buffer.append(" ");
} else {
buffer.append("*");
}
}
}
buffer.append("\"");
if (slop != 0) {
buffer.append("~");
buffer.append(slop);
}
return buffer.toString();
}
/**
* Returns true if o is equal to this.
*/
@Override
public boolean equals(Object o) {
if (sameClassAs(o) == false) {
return false;
}
MultiPhrasePrefixQuery other = (MultiPhrasePrefixQuery) o;
return this.slop == other.slop
&& termArraysEquals(this.termArrays, other.termArrays)
&& this.positions.equals(other.positions);
}
/**
* Returns a hash code value for this object.
*/
@Override
public int hashCode() {
return classHash()
^ slop
^ termArraysHashCode()
^ positions.hashCode();
}
// Breakout calculation of the termArrays hashcode
private int termArraysHashCode() {
int hashCode = 1;
for (final Term[] termArray : termArrays) {
hashCode = 31 * hashCode
+ (termArray == null ? 0 : Arrays.hashCode(termArray));
}
return hashCode;
}
// Breakout calculation of the termArrays equals
private boolean termArraysEquals(List termArrays1, List termArrays2) {
if (termArrays1.size() != termArrays2.size()) {
return false;
}
ListIterator iterator1 = termArrays1.listIterator();
ListIterator iterator2 = termArrays2.listIterator();
while (iterator1.hasNext()) {
Term[] termArray1 = iterator1.next();
Term[] termArray2 = iterator2.next();
if (!(termArray1 == null ? termArray2 == null : Arrays.equals(termArray1,
termArray2))) {
return false;
}
}
return true;
}
public String getField() {
return field;
}
}