public void RemoveNode(LRUNode <T> node)
{
node.Previous.Next = node.Next;
node.Next.Previous = node.Previous;
node.Next = null;
node.Previous = null;
}
public void AddToTop(LRUNode <T> node)
{
node.Next = Head.Next;
Head.Next.Previous = node;
node.Previous = Head;
Head.Next = node;
}
public void Add(string key, T value)
{
if (DataSource.ContainsKey(key))
{
LRUNode <T> node = DataSource[key];
DoubleLinkedList.RemoveNode(node);
node.Value = value;
DoubleLinkedList.AddToTop(node);
}
else
{
if (Count == Capacity)
{
LRUNode <T> lru = DoubleLinkedList.RemoveLRUNode();
DataSource.TryRemove(lru.Key, out _);
Count--;
}
LRUNode <T> node = new LRUNode <T>(key, value);
DoubleLinkedList.AddToTop(node);
DataSource.TryAdd(key, node);
Count++;
}
}
public LRUNode <T> RemoveLRUNode()
{
LRUNode <T> target = Tail.Previous;
RemoveNode(target);
return(target);
}
public LRUDoubleLinkedList()
{
Head = new LRUNode <T>();
Tail = new LRUNode <T>();
Head.Next = Tail;
Tail.Previous = Head;
}
public T Get(string key)
{
if (!DataSource.ContainsKey(key))
{
return(null);
}
LRUNode <T> node = DataSource[key];
DoubleLinkedList.RemoveNode(node);
DoubleLinkedList.AddToTop(node);
return(node.Value);
}