/// <summary>
/// Insert single item on scope start, and remove on scope exit
/// </summary>
/// <param name="singleItem">Item to insert in scope</param>
/// <param name="existing">Existing hashset to update</param>
/// <param name="forceHashSet">Force allocation of real hashset-container</param>
public SingleItemScopedInsert(T singleItem, ref SingleItemOptimizedHashSet <T> existing, bool forceHashSet)
{
_singleItem = singleItem;
if (existing._hashset != null)
{
existing._hashset.Add(singleItem);
_hashset = existing._hashset;
}
else if (forceHashSet)
{
existing = new SingleItemOptimizedHashSet <T>(singleItem, existing);
existing.Add(singleItem);
_hashset = existing._hashset;
}
else
{
existing = new SingleItemOptimizedHashSet <T>(singleItem, existing);
_hashset = null;
}
}
public SingleItemOptimizedHashSet(T singleItem, SingleItemOptimizedHashSet <T> existing)
{
if (existing._hashset != null)
{
_hashset = new HashSet <T>(existing._hashset);
_hashset.Add(singleItem);
_singleItem = default(T);
}
else if (existing.Count == 1)
{
_hashset = new HashSet <T>();
_hashset.Add(existing._singleItem);
_hashset.Add(singleItem);
_singleItem = default(T);
}
else
{
_hashset = null;
_singleItem = singleItem;
}
}
public SingleItemOptimizedHashSet(T singleItem, SingleItemOptimizedHashSet <T> existing, IEqualityComparer <T> comparer = null)
{
_comparer = existing._comparer ?? comparer ?? EqualityComparer <T> .Default;
if (existing._hashset != null)
{
_hashset = new HashSet <T>(existing._hashset, _comparer);
_hashset.Add(singleItem);
_singleItem = default(T);
}
else if (existing.Count == 1)
{
_hashset = new HashSet <T>(_comparer);
_hashset.Add(existing._singleItem);
_hashset.Add(singleItem);
_singleItem = default(T);
}
else
{
_hashset = null;
_singleItem = singleItem;
}
}