package org.apache.lucene.queryparser.flexible.standard.processors;
/*
* 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.
*/
import java.util.LinkedList;
import java.util.List;
import org.apache.lucene.queryparser.flexible.core.QueryNodeException;
import org.apache.lucene.queryparser.flexible.core.config.QueryConfigHandler;
import org.apache.lucene.queryparser.flexible.core.nodes.BooleanQueryNode;
import org.apache.lucene.queryparser.flexible.core.nodes.FieldableNode;
import org.apache.lucene.queryparser.flexible.core.nodes.GroupQueryNode;
import org.apache.lucene.queryparser.flexible.core.nodes.OrQueryNode;
import org.apache.lucene.queryparser.flexible.core.nodes.QueryNode;
import org.apache.lucene.queryparser.flexible.core.processors.QueryNodeProcessorImpl;
import org.apache.lucene.queryparser.flexible.standard.config.StandardQueryConfigHandler.ConfigurationKeys;
/**
* This processor is used to expand terms so the query looks for the same term
* in different fields. It also boosts a query based on its field. <br/>
* <br/>
* This processor looks for every {@link FieldableNode} contained in the query
* node tree. If a {@link FieldableNode} is found, it checks if there is a
* {@link ConfigurationKeys#MULTI_FIELDS} defined in the {@link QueryConfigHandler}. If
* there is, the {@link FieldableNode} is cloned N times and the clones are
* added to a {@link BooleanQueryNode} together with the original node. N is
* defined by the number of fields that it will be expanded to. The
* {@link BooleanQueryNode} is returned. <br/>
*
* @see ConfigurationKeys#MULTI_FIELDS
*/
public class MultiFieldQueryNodeProcessor extends QueryNodeProcessorImpl {
private boolean processChildren = true;
public MultiFieldQueryNodeProcessor() {
// empty constructor
}
@Override
protected QueryNode postProcessNode(QueryNode node) throws QueryNodeException {
return node;
}
@Override
protected void processChildren(QueryNode queryTree) throws QueryNodeException {
if (this.processChildren) {
super.processChildren(queryTree);
} else {
this.processChildren = true;
}
}
@Override
protected QueryNode preProcessNode(QueryNode node) throws QueryNodeException {
if (node instanceof FieldableNode) {
this.processChildren = false;
FieldableNode fieldNode = (FieldableNode) node;
if (fieldNode.getField() == null) {
CharSequence[] fields = getQueryConfigHandler().get(ConfigurationKeys.MULTI_FIELDS);
if (fields == null) {
throw new IllegalArgumentException(
"StandardQueryConfigHandler.ConfigurationKeys.MULTI_FIELDS should be set on the QueryConfigHandler");
}
if (fields != null && fields.length > 0) {
fieldNode.setField(fields[0]);
if (fields.length == 1) {
return fieldNode;
} else {
LinkedList<QueryNode> children = new LinkedList<QueryNode>();
children.add(fieldNode);
for (int i = 1; i < fields.length; i++) {
try {
fieldNode = (FieldableNode) fieldNode.cloneTree();
fieldNode.setField(fields[i]);
children.add(fieldNode);
} catch (CloneNotSupportedException e) {
// should never happen
}
}
return new GroupQueryNode(new OrQueryNode(children));
}
}
}
}
return node;
}
@Override
protected List<QueryNode> setChildrenOrder(List<QueryNode> children)
throws QueryNodeException {
return children;
}
}