HitQueue.cs

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/* 
 * 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 Lucene.Net.Util;

namespace Lucene.Net.Search
{
    
    public sealed class HitQueue : PriorityQueue<ScoreDoc>
    {
        
        private bool prePopulate;
        
        public /*internal*/ HitQueue(int size, bool prePopulate)
        {
            this.prePopulate = prePopulate;
            Initialize(size);
        }
        
        // Returns null if prePopulate is false.

        protected internal override ScoreDoc SentinelObject
        {
            get
            {
                // 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(ScoreDoc hitA, ScoreDoc hitB)
        {
            if (hitA.Score == hitB.Score)
                return hitA.Doc > hitB.Doc;
            else
                return hitA.Score < hitB.Score;
        }
    }
}