public bool Add(int key, int cacheItem)
{
LRUCacheNode cacheNode = null;
if (cacheMap.TryGetValue(key.ToString(), out cacheNode))
{
return(false);
}
cacheNode = new LRUCacheNode()
{
Key = key,
Value = cacheItem
};
if (head == null)
{
head = cacheNode;
tail = cacheNode;
}
else
{
if (cacheMap.Count >= capacity)
{
this.RemoveTailNode();
}
cacheNode.Next = head;
head.Previous = cacheNode;
head = cacheNode;
}
return(cacheMap.TryAdd(key.ToString(), cacheNode));
}
public bool Remove(int key)
{
LRUCacheNode cacheNode;
if (this.cacheMap.TryGetValue(key.ToString(), out cacheNode))
{
if (cacheNode.Previous != null)
{
cacheNode.Previous.Next = cacheNode.Next;
}
else
{
head = cacheNode.Next;
}
if (cacheNode.Next != null)
{
cacheNode.Next.Previous = cacheNode.Previous;
}
else
{
tail = cacheNode.Previous;
}
cacheNode.Next = null;
cacheNode.Previous = null;
return(this.cacheMap.TryRemove(key.ToString(), out cacheNode));
}
return(false);
}
private void RemoveTailNode()
{
LRUCacheNode cacheNode;
if (this.cacheMap.TryRemove(tail.Key.ToString(), out cacheNode))
{
tail.Previous.Next = null;
tail = tail.Previous;
}
}
public void DisplayCacheMap()
{
StringBuilder sb = new StringBuilder();
LRUCacheNode cacheNode = head;
while (cacheNode != null)
{
sb.Append(cacheNode.Key);
cacheNode = cacheNode.Next;
if (cacheNode != null)
{
sb.Append("-->");
}
}
Console.WriteLine(sb.ToString());
}
public object GetCacheItem(int key)
{
LRUCacheNode cacheNode;
if (this.cacheMap.TryGetValue(key.ToString(), out cacheNode))
{
if (cacheNode.Previous != null)
{
cacheNode.Previous.Next = cacheNode.Next;
}
if (cacheNode.Next != null)
{
cacheNode.Next.Previous = cacheNode.Previous;
}
cacheNode.Next = head;
head.Previous = cacheNode;
head = cacheNode;
return(cacheNode.Value);
}
return(null);
}