/// <summary>
/// Adds an element to the current set and returns a value to indicate if the element was successfully added.
/// </summary>
/// <returns>
/// true if the element is added to the set; false if the element is already in the set.
/// </returns>
/// <param name="item">The element to add to the set.</param>
public bool Add(T item)
{
if (_elements.ContainsKey(item))
{
return(false);
}
var node = new LinkedHashNode <T>(item)
{
Previous = _last
};
if (_first == null)
{
_first = node;
}
if (_last != null)
{
_last.Next = node;
}
_last = node;
_elements.Add(item, node);
return(true);
}
/// <inheritdoc />
public bool MoveNext()
{
if (_node == null)
{
return(false);
}
_current = _node.Value;
_node = _node.Next;
return(true);
}
/// <summary>
/// Unlink a node from the linked list by updating the node pointers in
/// its preceeding and subsequent node. Also update the _first and _last
/// pointers if necessary.
/// </summary>
private void Unlink(LinkedHashNode <T> node)
{
if (node.Previous != null)
{
node.Previous.Next = node.Next;
}
if (node.Next != null)
{
node.Next.Previous = node.Previous;
}
if (ReferenceEquals(node, _first))
{
_first = node.Next;
}
if (ReferenceEquals(node, _last))
{
_last = node.Previous;
}
}
/// <summary>
/// Removes all items from the <see cref="T:System.Collections.Generic.ICollection`1"/>.
/// </summary>
/// <exception cref="T:System.NotSupportedException">The <see cref="T:System.Collections.Generic.ICollection`1"/> is read-only. </exception>
public void Clear()
{
_elements.Clear();
_first = null;
_last = null;
}
internal Enumerator(LinkedHashSet <T> set)
{
_current = default(T);
_node = set._first;
}
