/*
* 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.
*/
using System;
using PriorityQueue = Lucene.Net.Util.PriorityQueue;
namespace Lucene.Net.Search
{
public sealed class HitQueue:PriorityQueue
{
private bool prePopulate;
/// Creates a new instance with size elements. If
/// prePopulate is set to true, the queue will pre-populate itself
/// with sentinel objects and set its to size. In
/// that case, you should not rely on to get the number of
/// actual elements that were added to the queue, but keep track yourself.
/// NOTE: in case prePopulate is true, you should pop
/// elements from the queue using the following code example:
///
///
/// PriorityQueue pq = new HitQueue(10, true); // pre-populate.
/// ScoreDoc top = pq.top();
///
/// // Add/Update one element.
/// top.score = 1.0f;
/// top.doc = 0;
/// top = (ScoreDoc) pq.updateTop();
/// int totalHits = 1;
///
/// // Now pop only the elements that were *truly* inserted.
/// // First, pop all the sentinel elements (there are pq.size() - totalHits).
/// for (int i = pq.size() - totalHits; i > 0; i--) pq.pop();
///
/// // Now pop the truly added elements.
/// ScoreDoc[] results = new ScoreDoc[totalHits];
/// for (int i = totalHits - 1; i >= 0; i--) {
/// results[i] = (ScoreDoc) pq.pop();
/// }
///
///
/// NOTE: This class pre-allocate a full array of
/// length size.
///
///
/// the requested size of this queue.
///
/// specifies whether to pre-populate the queue with sentinel values.
///
///
///
public /*internal*/ HitQueue(int size, bool prePopulate)
{
this.prePopulate = prePopulate;
Initialize(size);
}
// Returns null if prePopulate is false.
protected internal override System.Object GetSentinelObject()
{
// Always set the doc Id to MAX_VALUE so that it won't be favored by
// lessThan. This generally should not happen since if score is not NEG_INF,
// TopScoreDocCollector will always add the object to the queue.
return !prePopulate?null:new ScoreDoc(System.Int32.MaxValue, System.Single.NegativeInfinity);
}
public override bool LessThan(System.Object a, System.Object b)
{
ScoreDoc hitA = (ScoreDoc) a;
ScoreDoc hitB = (ScoreDoc) b;
if (hitA.score == hitB.score)
return hitA.doc > hitB.doc;
else
return hitA.score < hitB.score;
}
}
}