src/Lucene.Net.Queries/Function/ValueSources/TotalTermFreqValueSource.cs

/*
 * 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.Collections;
using Lucene.Net.Index;
using Lucene.Net.Queries.Function.DocValues;
using Lucene.Net.Search;
using Lucene.Net.Util;

namespace Lucene.Net.Queries.Function.ValueSources
{
    /// <summary>
    /// <code>TotalTermFreqValueSource</code> returns the total term freq 
    /// (sum of term freqs across all documents).
    /// Returns -1 if frequencies were omitted for the field, or if 
    /// the codec doesn't support this statistic.
    /// @lucene.internal
    /// </summary>
    public class TotalTermFreqValueSource : ValueSource
    {
        protected readonly string field;
        protected readonly string indexedField;
        protected readonly string val;
        protected readonly BytesRef indexedBytes;

        public TotalTermFreqValueSource(string field, string val, string indexedField, BytesRef indexedBytes)
        {
            this.field = field;
            this.val = val;
            this.indexedField = indexedField;
            this.indexedBytes = indexedBytes;
        }

        public virtual string Name
        {
            get { return "totaltermfreq"; }
        }

        public override string Description
        {
            get { return Name + '(' + field + ',' + val + ')'; }
        }

        public override FunctionValues GetValues(IDictionary context, AtomicReaderContext readerContext)
        {
            return (FunctionValues)context[this];
        }

        public override void CreateWeight(IDictionary context, IndexSearcher searcher)
        {
            long totalTermFreq = 0;
            foreach (var readerContext in searcher.TopReaderContext.Leaves)
            {
                long val = readerContext.Reader.TotalTermFreq(new Term(indexedField, indexedBytes));
                if (val == -1)
                {
                    totalTermFreq = -1;
                    break;
                }
                else
                {
                    totalTermFreq += val;
                }
            }
            var ttf = totalTermFreq;
            context[this] = new LongDocValuesAnonymousInnerClassHelper(this, this, ttf);
        }

        private class LongDocValuesAnonymousInnerClassHelper : LongDocValues
        {
            private readonly TotalTermFreqValueSource outerInstance;

            private readonly long ttf;

            public LongDocValuesAnonymousInnerClassHelper(TotalTermFreqValueSource outerInstance, TotalTermFreqValueSource @this, long ttf)
                : base(@this)
            {
                this.outerInstance = outerInstance;
                this.ttf = ttf;
            }

            public override long LongVal(int doc)
            {
                return ttf;
            }
        }

        public override int GetHashCode()
        {
            return this.GetType().GetHashCode() + indexedField.GetHashCode() * 29 + indexedBytes.GetHashCode();
        }

        public override bool Equals(object o)
        {
            if (this.GetType() != o.GetType())
            {
                return false;
            }
            var other = (TotalTermFreqValueSource)o;
            return this.indexedField.Equals(other.indexedField) && this.indexedBytes.Equals(other.indexedBytes);
        }
    }
}