FieldDocSortedHitQueue.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
{
    
    class FieldDocSortedHitQueue : PriorityQueue<FieldDoc>
    {
        internal volatile SortField[] fields = null;
        
        // used in the case where the fields are sorted by locale
        // based strings
        internal volatile System.Globalization.CompareInfo[] collators;
        
        
        internal FieldDocSortedHitQueue(int size)
        {
            Initialize(size);
        }
        
        
        internal virtual void  SetFields(SortField[] fields)
        {
            lock (this)
            {
                this.fields = fields;
                this.collators = HasCollators(fields);
            }
        }

        internal virtual SortField[] GetFields()
        {
            return fields;
        }


        private System.Globalization.CompareInfo[] HasCollators(SortField[] fields)
        {
            if (fields == null)
                return null;
            System.Globalization.CompareInfo[] ret = new System.Globalization.CompareInfo[fields.Length];
            for (int i = 0; i < fields.Length; ++i)
            {
                System.Globalization.CultureInfo locale = fields[i].Locale;
                if (locale != null)
                    ret[i] = locale.CompareInfo;
            }
            return ret;
        }
        
        
        public override bool LessThan(FieldDoc docA, FieldDoc docB)
        {
            int n = fields.Length;
            int c = 0;
            for (int i = 0; i < n && c == 0; ++i)
            {
                int type = fields[i].Type;
                if(type == SortField.STRING)
                {
                    string s1 = (string) docA.fields[i];
                    string s2 = (string) docB.fields[i];
                    // null values need to be sorted first, because of how FieldCache.getStringIndex()
                    // works - in that routine, any documents without a value in the given field are
                    // put first.  If both are null, the next SortField is used
                    if (s1 == null)
                    {
                        c = (s2 == null) ? 0 : -1;
                    }
                    else if (s2 == null)
                    {
                        c = 1;
                    }
                    else if (fields[i].Locale == null)
                    {
                        c = s1.CompareTo(s2);
                    }
                    else
                    {
                        c = collators[i].Compare(s1, s2);
                    }
                }
                else
                {
                    c = docA.fields[i].CompareTo(docB.fields[i]);
                    if (type == SortField.SCORE)
                    {
                        c = -c;
                    }
                }
                if (fields[i].Reverse)
                {
                    c = - c;
                }
            }
            
            // avoid random sort order that could lead to duplicates (bug #31241):
            if (c == 0)
                return docA.Doc > docB.Doc;
            
            return c > 0;
        }
    }
}