// 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 "ThreadSpecificSingleton.h"

#include "../system/DisableWarningsPush.h"
#include <boost/thread.hpp>
#include "../system/DisableWarningsPop.h"

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
 */
template<class T, class X>
class ThreadSpecificSingletonNoConstruct
{
	private:
		boost::thread_specific_ptr<T> instance;

		static void cleanup_function (T *p) { }
		
	public:
		ThreadSpecificSingletonNoConstruct () :
			instance(&cleanup_function) { }
		
		virtual ~ThreadSpecificSingletonNoConstruct () {}
	
		virtual void setInstance (T *instance)
		{
			this->instance.release();
			this->instance.reset(instance);
		}

		void deleteInstance()
		{
			delete this->instance.release();
		}

		virtual T *p()
		{
			return instance.get();
		}

		/**********************************************************************
		 *              operator overloads to simplify use
		 **********************************************************************/

		operator T *()
		{
			return p();
		}

		T *operator ->()
		{
			return p();
		}

		T &operator *()
		{
			return *p();
		}
} ;

/**
 * a Singleton container, whose contained instance is constructed on its
 * first request
 *
 * T defines the class pointer type
 * X defines the allocation class type
 */
template<class T, class X>
class ThreadSpecificSingleton : public ThreadSpecificSingletonNoConstruct<T>
{
	protected:
		typedef ThreadSpecificSingletonNoConstruct<T> Super;
	public:
		virtual void setInstance (T *instance)
		{
			Super::deleteInstance();
			Super::setInstance(instance);
		}

		T *p()
		{
			T *p = Super::p();
			if (!p)
				 Super::setInstance(p = new X());

			return p;
		}

		/**********************************************************************
		 *              operator overloads to simplify use
		 **********************************************************************/

		operator T *()
		{
			return p();
		}

		T *operator ->()
		{
			return p();
		}

		T &operator *()
		{
			return *p();
		}
} ;

} // namespace utilities 
} // namespace