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tjp/core/singleton/Singleton.hpp

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+// TJP COPYRIGHT HEADER
+
+/**
+ * legal header 
+ *
+ * ============================================================================
+ * TJP	10/11/01		Got rid of the constructed singleton, it was essentially
+ *		a pointer!
+ *
+ * @author	Timothy Prepscius
+ * @created 3/../01
+ */
+
+#pragma once
+
+#include "Singleton.h"
+
+#include "../containers/FilledArray.hpp"
+
+namespace timprepscius {
+namespace core {
+
+/**
+ * a Singleton container, whose contained instance is constructed on its
+ * first request
+ *
+ * T defines the class pointer type
+ * X defines the allocation class type
+ */
+class Singletons
+{
+protected:
+	friend class Singleton_;
+	typedef FilledArray<class Singleton_ *> Singletons_;
+	static Singletons_ &singletons();
+
+public:
+	static void clearAll ();
+} ;
+ 
+class Singleton_
+{
+protected:
+	friend class Singletons;
+	virtual void clear () {}
+
+public:
+	Singleton_ ();
+	virtual ~Singleton_ ();
+} ;
+ 
+template<class T, class X>
+class Singleton : Singleton_
+{
+	private:
+		T *instance;
+
+		void clear () override
+		{
+			deleteInstance();
+		}
+
+	public:
+		Singleton()
+		{
+			instance = nullptr;
+		}
+
+		virtual ~Singleton()
+		{
+			deleteInstance();
+		}
+
+		void setInstance (T *instance)
+		{
+			if (this->instance)
+				delete instance;
+
+			this->instance = instance;
+		}
+
+		void verifyInstance()
+		{
+			if (instance==nullptr)
+			{
+				instance = new X();
+			}
+		}
+
+		void deleteInstance()
+		{
+			delete instance;
+			instance = nullptr;
+		}
+
+		T *p()
+		{
+			verifyInstance();
+			return instance;
+		}
+
+		/**********************************************************************
+		 *              operator overloads to simplify use
+		 **********************************************************************/
+
+		template<typename U>
+		operator U *()
+		{
+			return p();
+		}
+
+		T *operator ->()
+		{
+			return p();
+		}
+
+		T &operator *()
+		{
+			return *p();
+		}
+} ;
+
+} // namespace
+} // namespace
+