blob: 6e533b9671fcf306fb4c5ca10a77f12039a8f5cb [file] [log] [blame]
using Lucene.Net.Index;
using Lucene.Net.Util;
using System.IO;
namespace Lucene.Net.Search.Grouping.Terms
{
/*
* 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.
*/
/// <summary>
/// Concrete implementation of <see cref="AbstractFirstPassGroupingCollector{BytesRef}"/> that groups based on
/// field values and more specifically uses <see cref="SortedDocValues"/>
/// to collect groups.
///
/// @lucene.experimental
/// </summary>
public class TermFirstPassGroupingCollector : AbstractFirstPassGroupingCollector<BytesRef>
{
private readonly BytesRef scratchBytesRef = new BytesRef();
private SortedDocValues index;
private readonly string groupField; // LUCENENET: marked readonly
/// <summary>
/// Create the first pass collector.
/// </summary>
/// <param name="groupField">
/// The field used to group
/// documents. This field must be single-valued and
/// indexed (<see cref="FieldCache"/> is used to access its value
/// per-document).
/// </param>
/// <param name="groupSort">
/// The <see cref="Sort"/> used to sort the
/// groups. The top sorted document within each group
/// according to groupSort, determines how that group
/// sorts against other groups. This must be non-null,
/// ie, if you want to groupSort by relevance use
/// <see cref="Sort.RELEVANCE"/>.
/// </param>
/// <param name="topNGroups">
/// How many top groups to keep.
/// </param>
/// <exception cref="IOException">When I/O related errors occur</exception>
public TermFirstPassGroupingCollector(string groupField, Sort groupSort, int topNGroups)
: base(groupSort, topNGroups)
{
this.groupField = groupField;
}
protected override BytesRef GetDocGroupValue(int doc)
{
int ord = index.GetOrd(doc);
if (ord == -1)
{
return null;
}
else
{
index.LookupOrd(ord, scratchBytesRef);
return scratchBytesRef;
}
}
protected override BytesRef CopyDocGroupValue(BytesRef groupValue, BytesRef reuse)
{
if (groupValue == null)
{
return null;
}
else if (reuse != null)
{
reuse.CopyBytes(groupValue);
return reuse;
}
else
{
return BytesRef.DeepCopyOf(groupValue);
}
}
public override void SetNextReader(AtomicReaderContext context)
{
base.SetNextReader(context);
index = FieldCache.DEFAULT.GetTermsIndex(context.AtomicReader, groupField);
}
}
}