GroupJoinHashLookupBuilder.cs

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using System.Collections.Generic;
using System.Threading;
 
namespace System.Linq.Parallel;
 
internal sealed class GroupJoinHashLookupBuilder<TElement, TOrderKey, THashKey> : HashLookupBuilder<IEnumerable<TElement>, int, THashKey>
{
    private struct GroupJoinBaseHashBuilder : IBaseHashBuilder<TElement, TOrderKey>
    {
        private readonly HashLookup<THashKey, ListChunk<TElement>> _base;
 
        public GroupJoinBaseHashBuilder(HashLookup<THashKey, ListChunk<TElement>> baseLookup)
        {
            _base = baseLookup;
        }
 
        public bool Add(THashKey hashKey, TElement element, TOrderKey orderKey)
        {
            bool result = true;
            ListChunk<TElement> value = null;
            if (!_base.TryGetValue(hashKey, ref value))
            {
                value = new ListChunk<TElement>(2);
                _base.Add(hashKey, value);
                result = false;
            }
            value.Add(element);
            return result;
        }
    }
 
    private sealed class GroupJoinHashLookup : GroupJoinHashLookup<THashKey, TElement, ListChunk<TElement>, int>
    {
        protected override int EmptyValueKey => -559038737;
 
        internal GroupJoinHashLookup(HashLookup<THashKey, ListChunk<TElement>> lookup)
            : base(lookup)
        {
        }
 
        protected override Pair<IEnumerable<TElement>, int> CreateValuePair(ListChunk<TElement> baseValue)
        {
            return new Pair<IEnumerable<TElement>, int>(baseValue, -559038737);
        }
    }
 
    private readonly QueryOperatorEnumerator<Pair<TElement, THashKey>, TOrderKey> _dataSource;
 
    private readonly IEqualityComparer<THashKey> _keyComparer;
 
    internal GroupJoinHashLookupBuilder(QueryOperatorEnumerator<Pair<TElement, THashKey>, TOrderKey> dataSource, IEqualityComparer<THashKey> keyComparer)
    {
        _dataSource = dataSource;
        _keyComparer = keyComparer;
    }
 
    public override HashJoinHashLookup<THashKey, IEnumerable<TElement>, int> BuildHashLookup(CancellationToken cancellationToken)
    {
        HashLookup<THashKey, ListChunk<TElement>> hashLookup = new HashLookup<THashKey, ListChunk<TElement>>(_keyComparer);
        BuildBaseHashLookup<GroupJoinBaseHashBuilder, TElement, TOrderKey>(baseHashBuilder: new GroupJoinBaseHashBuilder(hashLookup), dataSource: _dataSource, cancellationToken: cancellationToken);
        return new GroupJoinHashLookup(hashLookup);
    }
}