private void AddKey(int key, LRUNode value)
{
if (!InCache(key))
{
_map.Add(key, value);
}
}
public void Put(int key, int value)
{
if (InCache(key))
{
var node = GetNode(key);
node.Value = value;
RemoveNode(node);
AppendNode(node);
}
else
{
var node = new LRUNode(key, value);
if (IsFull())
{
RemoveKey(_end.Key);
RemoveNode(_end);
AppendNode(node);
}
else
{
AppendNode(node);
}
AddKey(key, node);
}
}
private void AppendNode(LRUNode node)
{
node.Next = _start;
node.Previous = null;
if (_start != null)
{
_start.Previous = node;
}
_start = node;
if (_end == null)
{
_end = _start;
}
}
private void RemoveNode(LRUNode node)
{
if (node.Previous == null)
{
_start = node.Next;
}
else
{
node.Previous.Next = node.Next;
}
if (node.Next == null)
{
_end = node.Previous;
}
else
{
node.Next.Previous = node.Previous;
}
}