//===-- MIUtilSingletonBase.h -----------------------------------*- C++ -*-===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//

//++
// File:		MIUtilSingletonBase.h
//
// Overview:	MI::ISingleton interface.
//
// Environment:	Compilers:	Visual C++ 12.
//							gcc (Ubuntu/Linaro 4.8.1-10ubuntu9) 4.8.1
//				Libraries:	See MIReadmetxt. 
//
// Copyright:	None.
//--

#pragma once

namespace MI
{

//	MI::ISingleton base class usage:
//
//	class CMIDerivedClass
//		: public MI::ISingleton< CMIDerivedClass >
//	{
//		friend MI::ISingleton< CMIDerivedClass >;
//
//	// Overridden:		
//	public:
//		// From MI::ISingleton
//		virtual bool Initialize( void );
//		virtual bool Shutdown( void );
//	};

//++ ============================================================================
// Details:	Base class for the singleton pattern.
// Gotchas:	Derived class must specify MI::ISingleton<> as a friend class.
// Authors:	Aidan Dodds 17/03/2014.
// Changes:	None.
//--
template< typename T >
class ISingleton
{
// Statics:
public:
	// Return an instance of the derived class
	static T & Instance( void )
	{
		// This will fail if the derived class has not
		// declared itself to be a friend of MI::ISingleton
		static T instance;

		return instance;
	}

// Overrideable:
public:
	virtual bool Initialize( void ) = 0;
	virtual bool Shutdown( void ) = 0;
	//
	/* dtor */ virtual ~ISingleton( void ) { };
};

} // namespace MI