internal static async Task <Lookup <TKey, TElement> > CreateAsync(IAsyncEnumerable <TElement> source, Func <TElement, TKey> keySelector, IEqualityComparer <TKey>?comparer, CancellationToken cancellationToken)
{
var lookup = new Lookup <TKey, TElement>(comparer);
await foreach (var item in source.WithCancellation(cancellationToken).ConfigureAwait(false))
{
var key = keySelector(item);
lookup.GetOrCreateGrouping(key).Add(item);
}
return(lookup);
}
internal static async Task <Lookup <TKey, TElement> > CreateAsync <TSource>(IAsyncEnumerable <TSource> source, Func <TSource, TKey> keySelector, Func <TSource, TElement> elementSelector, IEqualityComparer <TKey>?comparer, CancellationToken cancellationToken)
{
Debug.Assert(source != null);
Debug.Assert(keySelector != null);
Debug.Assert(elementSelector != null);
var lookup = new Lookup <TKey, TElement>(comparer);
await foreach (var item in source.WithCancellation(cancellationToken).ConfigureAwait(false))
{
var key = keySelector(item);
var group = lookup.GetOrCreateGrouping(key);
var element = elementSelector(item);
group.Add(element);
}
return(lookup);
}