Singleton.h

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/*
 *  Copyright (C) 2010 - 2015 Leonid Kostrykin
 *
 *  Chair of Medical Engineering (mediTEC)
 *  RWTH Aachen University
 *  Pauwelsstr. 20
 *  52074 Aachen
 *  Germany
 *
 */
 
#ifndef SINGLETON_H_6014714286
#define SINGLETON_H_6014714286
 
#include <Carna/base/CarnaException.h>
#include <Carna/base/noncopyable.h>
 
namespace Carna
{
 
namespace base
{
 
 
 
// ----------------------------------------------------------------------------------
// Singleton
// ----------------------------------------------------------------------------------
 
template< typename InstanceType >
class Singleton
{
 
    NON_COPYABLE
 
    static InstanceType* instancePtr;
 
protected:
 
    Singleton()
    {
        CARNA_ASSERT_EX( instancePtr == nullptr, "Multiple singleton instances created." );
        instancePtr = static_cast< InstanceType* >( this );
    }
 
    static void reset()
    {
        if( instancePtr != nullptr )
        {
            delete instancePtr;
        }
    }
 
public:
 
    typedef InstanceType Instance;
 
    virtual ~Singleton()
    {
        instancePtr = nullptr;
    }
 
    static InstanceType& instance()
    {
        return instancePtr == nullptr ? *new InstanceType() : *instancePtr;
    }
 
    static bool exists()
    {
        return instancePtr != nullptr;
    }
 
}; // Singleton
 
 
template< typename InstanceType >
InstanceType* Singleton< InstanceType >::instancePtr = nullptr;
 
 
 
}  // namespace Carna :: base
 
}  // namespace Carna
 
#endif // SINGLETON_H_6014714286