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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.index.query;
import org.apache.lucene.search.ConstantScoreQuery;
import org.apache.lucene.search.Query;
import org.elasticsearch.common.ParseField;
import org.elasticsearch.common.ParsingException;
import org.elasticsearch.common.io.stream.StreamInput;
import org.elasticsearch.common.io.stream.StreamOutput;
import org.elasticsearch.common.xcontent.XContentBuilder;
import org.elasticsearch.common.xcontent.XContentParser;
import java.io.IOException;
import java.util.Map;
import java.util.Objects;
/**
* A query that wraps a filter and simply returns a constant score equal to the
* query boost for every document in the filter.
*/
public class ConstantScoreQueryBuilder extends AbstractQueryBuilder<ConstantScoreQueryBuilder> {
public static final String NAME = "constant_score";
public static final ParseField QUERY_NAME_FIELD = new ParseField(NAME);
private static final ParseField INNER_QUERY_FIELD = new ParseField("filter", "query");
private final QueryBuilder<?> filterBuilder;
/**
* A query that wraps another query and simply returns a constant score equal to the
* query boost for every document in the query.
*
* @param filterBuilder The query to wrap in a constant score query
*/
public ConstantScoreQueryBuilder(QueryBuilder<?> filterBuilder) {
if (filterBuilder == null) {
throw new IllegalArgumentException("inner clause [filter] cannot be null.");
}
this.filterBuilder = filterBuilder;
}
/**
* Read from a stream.
*/
public ConstantScoreQueryBuilder(StreamInput in) throws IOException {
super(in);
filterBuilder = in.readNamedWriteable(QueryBuilder.class);
}
@Override
protected void doWriteTo(StreamOutput out) throws IOException {
out.writeNamedWriteable(filterBuilder);
}
/**
* @return the query that was wrapped in this constant score query
*/
public QueryBuilder<?> innerQuery() {
return this.filterBuilder;
}
@Override
protected void doXContent(XContentBuilder builder, Params params) throws IOException {
builder.startObject(NAME);
builder.field(INNER_QUERY_FIELD.getPreferredName());
filterBuilder.toXContent(builder, params);
printBoostAndQueryName(builder);
builder.endObject();
}
public static ConstantScoreQueryBuilder fromXContent(QueryParseContext parseContext) throws IOException {
XContentParser parser = parseContext.parser();
QueryBuilder<?> query = null;
boolean queryFound = false;
String queryName = null;
float boost = AbstractQueryBuilder.DEFAULT_BOOST;
String currentFieldName = null;
XContentParser.Token token;
while ((token = parser.nextToken()) != XContentParser.Token.END_OBJECT) {
if (token == XContentParser.Token.FIELD_NAME) {
currentFieldName = parser.currentName();
} else if (parseContext.isDeprecatedSetting(currentFieldName)) {
// skip
} else if (token == XContentParser.Token.START_OBJECT) {
if (parseContext.getParseFieldMatcher().match(currentFieldName, INNER_QUERY_FIELD)) {
if (queryFound) {
throw new ParsingException(parser.getTokenLocation(), "[" + ConstantScoreQueryBuilder.NAME + "]"
+ " accepts only one 'filter' element.");
}
query = parseContext.parseInnerQueryBuilder();
queryFound = true;
} else {
throw new ParsingException(parser.getTokenLocation(),
"[constant_score] query does not support [" + currentFieldName + "]");
}
} else if (token.isValue()) {
if (parseContext.getParseFieldMatcher().match(currentFieldName, AbstractQueryBuilder.NAME_FIELD)) {
queryName = parser.text();
} else if (parseContext.getParseFieldMatcher().match(currentFieldName, AbstractQueryBuilder.BOOST_FIELD)) {
boost = parser.floatValue();
} else {
throw new ParsingException(parser.getTokenLocation(),
"[constant_score] query does not support [" + currentFieldName + "]");
}
} else {
throw new ParsingException(parser.getTokenLocation(), "unexpected token [" + token + "]");
}
}
if (!queryFound) {
throw new ParsingException(parser.getTokenLocation(), "[constant_score] requires a 'filter' element");
}
ConstantScoreQueryBuilder constantScoreBuilder = new ConstantScoreQueryBuilder(query);
constantScoreBuilder.boost(boost);
constantScoreBuilder.queryName(queryName);
return constantScoreBuilder;
}
@Override
protected Query doToQuery(QueryShardContext context) throws IOException {
Query innerFilter = filterBuilder.toFilter(context);
if (innerFilter == null ) {
// return null so that parent queries (e.g. bool) also ignore this
return null;
}
return new ConstantScoreQuery(innerFilter);
}
@Override
public String getWriteableName() {
return NAME;
}
@Override
protected int doHashCode() {
return Objects.hash(filterBuilder);
}
@Override
protected boolean doEquals(ConstantScoreQueryBuilder other) {
return Objects.equals(filterBuilder, other.filterBuilder);
}
@Override
protected QueryBuilder<?> doRewrite(QueryRewriteContext queryRewriteContext) throws IOException {
QueryBuilder<?> rewrite = filterBuilder.rewrite(queryRewriteContext);
if (rewrite != filterBuilder) {
return new ConstantScoreQueryBuilder(rewrite);
}
return this;
}
@Override
protected void extractInnerHitBuilders(Map<String, InnerHitBuilder> innerHits) {
InnerHitBuilder.extractInnerHits(filterBuilder, innerHits);
}
}
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