RepeatEnumerable.cs

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using System.Collections.Generic;
using System.Diagnostics.CodeAnalysis;
 
namespace System.Linq.Parallel;
 
internal sealed class RepeatEnumerable<TResult> : ParallelQuery<TResult>, IParallelPartitionable<TResult>
{
    private sealed class RepeatEnumerator : QueryOperatorEnumerator<TResult, int>
    {
        private readonly TResult _element;
 
        private readonly int _count;
 
        private readonly int _indexOffset;
 
        private Shared<int> _currentIndex;
 
        internal RepeatEnumerator(TResult element, int count, int indexOffset)
        {
            _element = element;
            _count = count;
            _indexOffset = indexOffset;
        }
 
        internal override bool MoveNext([MaybeNullWhen(false)][AllowNull] ref TResult currentElement, ref int currentKey)
        {
            if (_currentIndex == null)
            {
                _currentIndex = new Shared<int>(-1);
            }
            if (_currentIndex.Value < _count - 1)
            {
                _currentIndex.Value++;
                currentElement = _element;
                currentKey = _currentIndex.Value + _indexOffset;
                return true;
            }
            return false;
        }
 
        internal override void Reset()
        {
            _currentIndex = null;
        }
    }
 
    private readonly TResult _element;
 
    private readonly int _count;
 
    internal RepeatEnumerable(TResult element, int count)
        : base(QuerySettings.Empty)
    {
        _element = element;
        _count = count;
    }
 
    public QueryOperatorEnumerator<TResult, int>[] GetPartitions(int partitionCount)
    {
        int num = (_count + partitionCount - 1) / partitionCount;
        QueryOperatorEnumerator<TResult, int>[] array = new QueryOperatorEnumerator<TResult, int>[partitionCount];
        int num2 = 0;
        int num3 = 0;
        while (num2 < partitionCount)
        {
            if (num3 + num > _count)
            {
                array[num2] = new RepeatEnumerator(_element, (num3 < _count) ? (_count - num3) : 0, num3);
            }
            else
            {
                array[num2] = new RepeatEnumerator(_element, num, num3);
            }
            num2++;
            num3 += num;
        }
        return array;
    }
 
    public override IEnumerator<TResult> GetEnumerator()
    {
        return new RepeatEnumerator(_element, _count, 0).AsClassicEnumerator();
    }
}