internal static NullDictionary <TKey, IReadOnlyList <TSource> > ToGroupedNullDictionary <TSource, TKey>(this IEnumerable <TSource> Source, Func <TSource, TKey> KeySelector)
{
var dictionary = new NullDictionary <TKey, IReadOnlyList <TSource> >();
foreach (var item in Source.GroupBy(KeySelector))
{
dictionary.Add(item.Key, item.ToList().AsReadOnly());
}
return(dictionary);
}
internal static NullDictionary <TKey, TSource> ToNullDictionary <TSource, TKey>(this IEnumerable <TSource> Source, Func <TSource, TKey> KeySelector)
{
var dictionary = new NullDictionary <TKey, TSource>();
foreach (var item in Source)
{
dictionary.Add(KeySelector(item), item);
}
return(dictionary);
}
internal static NullDictionary <TKey, int> ToIndexNullDictionary <TSource, TKey>(this IList <TSource> Source, Func <TSource, TKey> KeySelector)
{
NullDictionary <TKey, int> dictionary = new NullDictionary <TKey, int>(Source.Count);
for (int i = 0; i < Source.Count; i++)
{
dictionary.Add(KeySelector(Source[i]), i);
}
return(dictionary);
}