OrderedGroupByElementSelectorQueryOperatorEnumerator.cs

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using System.Collections.Generic;
using System.Threading;
 
namespace System.Linq.Parallel;
 
internal sealed class OrderedGroupByElementSelectorQueryOperatorEnumerator<TSource, TGroupKey, TElement, TOrderKey> : OrderedGroupByQueryOperatorEnumerator<TSource, TGroupKey, TElement, TOrderKey>
{
    private readonly Func<TSource, TElement> _elementSelector;
 
    internal OrderedGroupByElementSelectorQueryOperatorEnumerator(QueryOperatorEnumerator<Pair<TSource, TGroupKey>, TOrderKey> source, Func<TSource, TGroupKey> keySelector, Func<TSource, TElement> elementSelector, IEqualityComparer<TGroupKey> keyComparer, IComparer<TOrderKey> orderComparer, CancellationToken cancellationToken)
        : base(source, keySelector, keyComparer, orderComparer, cancellationToken)
    {
        _elementSelector = elementSelector;
    }
 
    protected override HashLookup<Wrapper<TGroupKey>, GroupKeyData> BuildHashLookup()
    {
        HashLookup<Wrapper<TGroupKey>, GroupKeyData> hashLookup = new HashLookup<Wrapper<TGroupKey>, GroupKeyData>(new WrapperEqualityComparer<TGroupKey>(_keyComparer));
        Pair<TSource, TGroupKey> currentElement = default(Pair<TSource, TGroupKey>);
        TOrderKey currentKey = default(TOrderKey);
        int num = 0;
        while (_source.MoveNext(ref currentElement, ref currentKey))
        {
            if ((num++ & 0x3F) == 0)
            {
                _cancellationToken.ThrowIfCancellationRequested();
            }
            Wrapper<TGroupKey> key = new Wrapper<TGroupKey>(currentElement.Second);
            GroupKeyData value = null;
            if (hashLookup.TryGetValue(key, ref value))
            {
                if (_orderComparer.Compare(currentKey, value._orderKey) < 0)
                {
                    value._orderKey = currentKey;
                }
            }
            else
            {
                value = new GroupKeyData(currentKey, key.Value, _orderComparer);
                hashLookup.Add(key, value);
            }
            value._grouping.Add(_elementSelector(currentElement.First), currentKey);
        }
        for (int i = 0; i < hashLookup.Count; i++)
        {
            hashLookup[i].Value._grouping.DoneAdding();
        }
        return hashLookup;
    }
}