--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/Cache.cs	Tue Sep 11 16:28:53 2012 +0200
@@ -0,0 +1,72 @@
+using System;
+using System.Collections.Generic;
+
+namespace UCIS {
+	public class Cache<TKey, TValue> {
+		private Dictionary<TKey, WeakReference> _items;
+
+		public Cache() {
+			_items = new Dictionary<TKey, WeakReference>();
+		}
+
+		public int Count { get { return _items.Count; } }
+		public int getCount(bool checkAlive) {
+			Purge();
+			return _items.Count;
+		}
+
+		private void getItem(TKey key, out TValue value, out bool exists, out bool collected) {
+			WeakReference w;
+			lock (_items) {
+				if (!_items.TryGetValue(key, out w)) {
+					value = default(TValue);
+					exists = false;
+					collected = false;
+					return;
+				}
+				Object r = w.Target;
+				if (r == null) {
+					_items.Remove(key);
+					value = default(TValue);
+					exists = false;
+					collected = true;
+					return;
+				}
+				value = (TValue)r;
+				exists = true;
+				collected = false;
+				return;
+			}
+		}
+
+		public bool TryGetValue(TKey key, out TValue value) {
+			bool exists, collected;
+			getItem(key, out value, out exists, out collected);
+			return exists;
+		}
+
+		public void Purge() {
+			lock (_items) {
+				List<TKey> remove = new List<TKey>();
+				foreach (KeyValuePair<TKey, WeakReference> kvp in _items) {
+					if (!kvp.Value.IsAlive) remove.Add(kvp.Key);
+				}
+				foreach (TKey key in remove) {
+					_items.Remove(key);
+				}
+			}
+		}
+
+		public void Add(TKey key, TValue value) {
+			lock(_items) _items.Add(key, new WeakReference(value));
+		}
+
+		public bool Remove(TKey key) {
+			lock(_items) return _items.Remove(key);
+		}
+
+		public void Clear() {
+			_items.Clear();
+		}
+	}
+}
\ No newline at end of file