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Elasticsearch subproject :server
/*
* Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
* or more contributor license agreements. Licensed under the Elastic License
* 2.0 and the Server Side Public License, v 1; you may not use this file except
* in compliance with, at your election, the Elastic License 2.0 or the Server
* Side Public License, v 1.
*/
package org.elasticsearch.common.lucene.search;
import org.apache.lucene.index.IndexReader;
import org.apache.lucene.index.IndexReaderContext;
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.queries.SpanMatchNoDocsQuery;
import org.apache.lucene.search.BooleanQuery;
import org.apache.lucene.search.MultiTermQuery;
import org.apache.lucene.search.Query;
import org.apache.lucene.search.spans.SpanMultiTermQueryWrapper;
import org.apache.lucene.search.spans.SpanOrQuery;
import org.apache.lucene.search.spans.SpanQuery;
import org.apache.lucene.search.spans.SpanTermQuery;
import org.apache.lucene.util.AttributeSource;
import org.apache.lucene.util.BytesRef;
import java.io.IOException;
import java.util.Collection;
import java.util.HashSet;
import java.util.Set;
/**
* A span rewrite method that extracts the first maxExpansions
terms
* that match the {@link MultiTermQuery} in the terms dictionary.
* The rewrite throws an error if more than maxExpansions
terms are found and hardLimit
* is set.
*/
public class SpanBooleanQueryRewriteWithMaxClause extends SpanMultiTermQueryWrapper.SpanRewriteMethod {
private final int maxExpansions;
private final boolean hardLimit;
public SpanBooleanQueryRewriteWithMaxClause() {
this(BooleanQuery.getMaxClauseCount(), true);
}
public SpanBooleanQueryRewriteWithMaxClause(int maxExpansions, boolean hardLimit) {
this.maxExpansions = maxExpansions;
this.hardLimit = hardLimit;
}
public int getMaxExpansions() {
return maxExpansions;
}
public boolean isHardLimit() {
return hardLimit;
}
@Override
public SpanQuery rewrite(IndexReader reader, MultiTermQuery query) throws IOException {
final MultiTermQuery.RewriteMethod delegate = new MultiTermQuery.RewriteMethod() {
@Override
public Query rewrite(IndexReader reader, MultiTermQuery query) throws IOException {
Collection queries = collectTerms(reader, query);
if (queries.size() == 0) {
return new SpanMatchNoDocsQuery(query.getField(), "no expansion found for " + query.toString());
} else if (queries.size() == 1) {
return queries.iterator().next();
} else {
return new SpanOrQuery(queries.toArray(new SpanQuery[0]));
}
}
private Collection collectTerms(IndexReader reader, MultiTermQuery query) throws IOException {
Set queries = new HashSet<>();
IndexReaderContext topReaderContext = reader.getContext();
for (LeafReaderContext context : topReaderContext.leaves()) {
final Terms terms = context.reader().terms(query.getField());
if (terms == null) {
// field does not exist
continue;
}
final TermsEnum termsEnum = getTermsEnum(query, terms, new AttributeSource());
assert termsEnum != null;
if (termsEnum == TermsEnum.EMPTY) {
continue;
}
BytesRef bytes;
while ((bytes = termsEnum.next()) != null) {
if (queries.size() >= maxExpansions) {
if (hardLimit) {
throw new RuntimeException(
"["
+ query.toString()
+ " ] "
+ "exceeds maxClauseCount [ Boolean maxClauseCount is set to "
+ BooleanQuery.getMaxClauseCount()
+ "]"
);
} else {
return queries;
}
}
queries.add(new SpanTermQuery(new Term(query.getField(), bytes)));
}
}
return queries;
}
};
return (SpanQuery) delegate.rewrite(reader, query);
}
}