/// <summary>
/// Adds a new element to the cache, replacing and moving it to the front if the
/// element is already present.
/// </summary>
public void Add(TKey key, TValue value)
{
KeyInfo keyInfo;
if (_dict.TryGetValue(key, out keyInfo))
{
// remove original entry from the linked list
_list.Remove(keyInfo.List);
}
else if (_list.Count == _maxSize)
{
// we've reached capacity, remove the last used element...
LinkedListNode <TKey> node = _list.Last;
_list.RemoveLast();
bool res = _dict.Remove(node.Value);
Debug.Assert(res);
}
// add the new entry to the head of the list and into the dictionary
LinkedListNode <TKey> listNode = new LinkedListNode <TKey>(key);
_list.AddFirst(listNode);
_dict[key] = new CacheDict <TKey, TValue> .KeyInfo(value, listNode);
}