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tjp/core/singleton/ThreadSpecificSingleton.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 "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
+