internal static async Task <Lookup <TKey, TElement> > CreateForJoinAsync(IAsyncEnumerable <TElement> source, Func <TElement, TKey> keySelector, IEqualityComparer <TKey> comparer, CancellationToken cancellationToken)
{
var lookup = new Lookup <TKey, TElement>(comparer);
await foreach (var item in AsyncEnumerableExtensions.WithCancellation(source, cancellationToken).ConfigureAwait(false))
{
var key = keySelector(item);
if (key != null)
{
lookup.GetGrouping(key, create: true).Add(item);
}
}
return(lookup);
}
internal static async Task <LookupWithTask <TKey, TElement> > CreateAsync(IAsyncEnumerable <TElement> source, Func <TElement, CancellationToken, ValueTask <TKey> > keySelector, IEqualityComparer <TKey> comparer, CancellationToken cancellationToken)
{
Debug.Assert(source != null);
Debug.Assert(keySelector != null);
var lookup = new LookupWithTask <TKey, TElement>(comparer);
await foreach (var item in AsyncEnumerableExtensions.WithCancellation(source, cancellationToken).ConfigureAwait(false))
{
var key = await keySelector(item, cancellationToken).ConfigureAwait(false);
lookup.GetGrouping(key, create: true).Add(item);
}
return(lookup);
}
