Import all this stuff into a single repo called Serenity.

AK/Retainable.h

@@ -0,0 +1,43 @@
+#pragma once
+
+#include "Assertions.h"
+
+namespace AK {
+
+template<typename T>
+class Retainable {
+public:
+    Retainable() { }
+
+    void retain()
+    {
+        ASSERT(m_retainCount);
+        ++m_retainCount;
+    }
+
+    void release()
+    {
+        assert(m_retainCount);
+        if (!--m_retainCount)
+            delete static_cast<const T*>(this);
+    }
+
+    int retainCount() const
+    {
+        return m_retainCount;
+    }
+
+protected:
+    ~Retainable()
+    {
+        ASSERT(!m_retainCount);
+    }
+
+private:
+    int m_retainCount { 1 };
+};
+
+}
+
+using AK::Retainable;
+