NullableDoubleAverageAggregationOperator.cs

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using System.Collections.Generic;
using System.Threading;
 
namespace System.Linq.Parallel;
 
internal sealed class NullableDoubleAverageAggregationOperator : InlinedAggregationOperator<double?, Pair<double, long>, double?>
{
    private sealed class NullableDoubleAverageAggregationOperatorEnumerator<TKey> : InlinedAggregationOperatorEnumerator<Pair<double, long>>
    {
        private readonly QueryOperatorEnumerator<double?, TKey> _source;
 
        internal NullableDoubleAverageAggregationOperatorEnumerator(QueryOperatorEnumerator<double?, TKey> source, int partitionIndex, CancellationToken cancellationToken)
            : base(partitionIndex, cancellationToken)
        {
            _source = source;
        }
 
        protected override bool MoveNextCore(ref Pair<double, long> currentElement)
        {
            double num = 0.0;
            long num2 = 0L;
            QueryOperatorEnumerator<double?, TKey> source = _source;
            double? currentElement2 = null;
            TKey currentKey = default(TKey);
            int num3 = 0;
            while (source.MoveNext(ref currentElement2, ref currentKey))
            {
                if (currentElement2.HasValue)
                {
                    if ((num3++ & 0x3F) == 0)
                    {
                        _cancellationToken.ThrowIfCancellationRequested();
                    }
                    num += currentElement2.GetValueOrDefault();
                    num2 = checked(num2 + 1);
                }
            }
            currentElement = new Pair<double, long>(num, num2);
            return num2 > 0;
        }
 
        protected override void Dispose(bool disposing)
        {
            _source.Dispose();
        }
    }
 
    internal NullableDoubleAverageAggregationOperator(IEnumerable<double?> child)
        : base(child)
    {
    }
 
    protected override double? InternalAggregate(ref Exception singularExceptionToThrow)
    {
        checked
        {
            using IEnumerator<Pair<double, long>> enumerator = GetEnumerator(ParallelMergeOptions.FullyBuffered, suppressOrderPreservation: true);
            if (!enumerator.MoveNext())
            {
                return null;
            }
            Pair<double, long> current = enumerator.Current;
            while (enumerator.MoveNext())
            {
                current.First += enumerator.Current.First;
                current.Second += enumerator.Current.Second;
            }
            return current.First / (double)current.Second;
        }
    }
 
    protected override QueryOperatorEnumerator<Pair<double, long>, int> CreateEnumerator<TKey>(int index, int count, QueryOperatorEnumerator<double?, TKey> source, object sharedData, CancellationToken cancellationToken)
    {
        return new NullableDoubleAverageAggregationOperatorEnumerator<TKey>(source, index, cancellationToken);
    }
}