public ImmutableCompactList <T> Add(T item)
{
if (this.data == null)
{
if (item != null)
{
return(new ImmutableCompactList <T>(item));
}
else
{
return(new ImmutableCompactList <T>(SmallCollection <T> .NullItem));
}
}
else if (this.data is SmallCollection <T> shortList)
{
return(new ImmutableCompactList <T>(shortList.Add(item, FullListCreator)));
}
else if (this.data is T[] list)
{
// TODO: Switch to ImmutableList after some other threshold.
// This can become very slow if a lot of items are added.
Array.Resize(ref list, list.Length + 1);
list[list.Length - 1] = item;
return(new ImmutableCompactList <T>(list));
}
else
{
Debug.Assert(this.data is T);
return(new ImmutableCompactList <T>(SmallCollection <T> .Create((T)this.data, item)));
}
}
public bool Add(T item)
{
if (this.data == null)
{
if (item != null)
{
this.data = item;
}
else
{
this.data = SmallCollection <T> .NullItem;
}
return(true);
}
if (this.data is SmallCollection <T> shortList)
{
if (shortList.AddToSet(item, FullSetCreator, out object newSet))
{
this.data = newSet;
return(true);
}
return(false);
}
if (this.data is HashSet <T> set)
{
return(set.Add(item));
}
Debug.Assert(this.data is T);
T singleItem = (T)this.data;
if (!Comparer.Equals(item, singleItem))
{
this.data = SmallCollection <T> .Create(singleItem, item);
return(true);
}
return(false);
}
public CompactSet(T item1, T item2)
{
if (!Comparer.Equals(item1, item2))
{
this.data = SmallCollection <T> .Create(item1, item2);
}
else
{
if (item1 != null)
{
this.data = item1;
}
else
{
this.data = SmallCollection <T> .NullItem;
}
}
}
public bool Remove(T item)
{
if (this.data == null)
{
return(false);
}
if (this.data is SmallCollection <T> smallSet)
{
if (smallSet.Remove(item, out object?newSet))
{
this.data = newSet;
return(true);
}
return(false);
}
if (this.data is HashSet <T> set)
{
if (set.Remove(item))
{
if (set.Count <= SmallCollection <T> .MaxSize)
{
this.data = SmallCollection <T> .Create(set);
}
return(true);
}
}
if (Comparer.Equals((T)this.data, item))
{
this.data = null;
return(true);
}
return(false);
}
internal static object?CreateListData(IEnumerable <T> enumerable)
{
if (!(enumerable is ICollection <T> collection))
{
// Copy items into a temporary collection, to avoid
// enumerating the enumerator twice.
collection = new List <T>(enumerable);
}
int totalCount = collection.Count;
if (totalCount <= SmallCollection <T> .MaxSize)
{
return(SmallCollection <T> .Create(collection));
}
else
{
T[] array = new T[totalCount];
collection.CopyTo(array, 0);
return(array);
}
}