/*
* 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.grouping;
import java.io.IOException;
import java.util.Collection;
import org.apache.lucene.search.Scorer;
import org.apache.lucene.search.SimpleCollector;
import org.apache.lucene.util.BytesRef;
/**
* A collector that collects all groups that match the
* query. Only the group value is collected, and the order
* is undefined. This collector does not determine
* the most relevant document of a group.
* <p>
* This is an abstract version. Concrete implementations define
* what a group actually is and how it is internally collected.
*
* @lucene.experimental
*/
public abstract class AbstractAllGroupsCollector<GROUP_VALUE_TYPE> extends SimpleCollector {
/**
* Returns the total number of groups for the executed search.
* This is a convenience method. The following code snippet has the same effect: <pre>getGroups().size()</pre>
*
* @return The total number of groups for the executed search
*/
public int getGroupCount() {
return getGroups().size();
}
/**
* Returns the group values
* <p>
* This is an unordered collections of group values. For each group that matched the query there is a {@link BytesRef}
* representing a group value.
*
* @return the group values
*/
public abstract Collection<GROUP_VALUE_TYPE> getGroups();
// Empty not necessary
@Override
public void setScorer(Scorer scorer) throws IOException {}
@Override
public boolean needsScores() {
return false; // the result is unaffected by relevancy
}
}