// 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