internal static Lookup <TKey, TElement> Create <TSource>(IEnumerable <TSource> source, Func <TSource, TKey> keySelector, Func <TSource, TElement> elementSelector, IEqualityComparer <TKey>?comparer)
{
if (source == null)
{
throw new ArgumentNullException(nameof(source));
}
if (elementSelector == null)
{
throw new ArgumentNullException(nameof(elementSelector));
}
if (keySelector == null)
{
throw new ArgumentNullException(nameof(keySelector));
}
var nonNullComparer = comparer ?? EqualityComparer <TKey> .Default;
var result = new Lookup <TKey, TElement>(nonNullComparer);
var collections = new NullAwareDictionary <TKey, List <TElement> >(nonNullComparer);
foreach (var item in source)
{
var key = keySelector(item);
if (!collections.TryGetValue(key, out var collection))
{
collection = new List <TElement>();
collections.Add(key, collection);
}
if (!result._groupings.TryGetValue(key, out var grouping))
{
grouping = new Grouping <TKey, TElement>(key, collection);
result._groupings.Add(key, grouping);
}
collection.Add(elementSelector(item));
}
return(result);
}
public bool TryGetValue(T equalValue, out T actualValue)
{
if (_wrapped.TryGetValue(equalValue, out actualValue))
{
return(true);
}
actualValue = default !;
public IEnumerator <IGrouping <TKey, TElement> > GetEnumerator()
{
var groupings = new NullAwareDictionary <TKey, Tuple <Grouping <TKey, TElement>, List <TElement> > >(_comparer);
foreach (var item in _source)
{
var key = _keySelector(item);
if (!groupings.TryGetValue(key, out var tuple))
{
var collection = new List <TElement>();
tuple = new Tuple <Grouping <TKey, TElement>, List <TElement> >(new Grouping <TKey, TElement>(key, collection), collection);
groupings.Add(key, tuple);
}
tuple.Item2.Add(_elementSelector(item));
}
return(Enumerator(groupings));
}
public IEnumerator <TResult> GetEnumerator()
{
var groupings = new NullAwareDictionary <TKey, Lookup <TKey, TElement> .Grouping>(_comparer);
foreach (var item in _source)
{
var key = _keySelector(item);
Lookup <TKey, TElement> .Grouping grouping;
if (!groupings.TryGetValue(key, out grouping))
{
grouping = new Lookup <TKey, TElement> .Grouping(key);
groupings.Add(key, grouping);
}
grouping.Items.Add(_elementSelector(item));
}
return(Enumerator(groupings));
}
public bool TryGetValue(TKey key, out IGrouping <TKey, T> value)
{
if (_cache.TryGetValue(key, out value))
{
return(true);
}
foreach (var found in ProgressorWhere(Check))
{
value = found;
return(true);
}
return(false);
bool Check(IGrouping <TKey, T> item)
{
return(Comparer.Equals(key, item.Key));
}
}
