satdump/plugins/xrit_support/DecompWT/SmartPtr.h

/*
 * Copyright 2011-2019, European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT)
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#ifndef _SMARTPTR_H_
#define _SMARTPTR_H_

#include "ErrorHandling.h"
namespace Util
{

	/**
	 * thread safe pointer class
	 **/
	template <class T>
	class CSmartPtr
	{

	private:
		/**
		 * Holds address of heap memory and maintains counter of references to it.
		 **/
		class CCounted
		{
		private:
			T *m_Ptr; /** Start address of heap memory.**/
			unsigned long m_NumReferences;

		public:
			/**
			 * Stores address of heap memory, initializes number of references.
			 **/
			CCounted(T *i_Ptr)
			{
				m_Ptr = i_Ptr;
				m_NumReferences = 0;
			}

			/**
			 * Increments number of references.
			 **/
			void Use()
			{
				m_NumReferences++;
			}

			/**
			 * Decrements number of references,deletes itself when last reference dismisses.
			 **/
			void Dismiss()
			{
				if (0 == --m_NumReferences)
				{
					delete[] m_Ptr; // ORIGINAL WAS delete
									// delete this;
				}
			}

			/**
			 * Returns heap memory address and set sets own copy of the address to NULL to prevent deletion.
			 * @returns
			 * Heap memory address
			 **/
			T *Release()
			{
				/** Return the heap memory address.**/
				T *t = m_Ptr;
				m_Ptr = NULL;
				return t;
			}

			/**
			 * Operators to access the heap memory.
			 * @returns
			 * Address or value of dynamic object
			 **/
			operator T &() const { return *m_Ptr; }
			operator T *() const { return m_Ptr; }
			T *operator->() const { return m_Ptr; }
		};

		CCounted *m_Counted; /** Start address of heap memory and reference counter.**/

	public:
		/**
		 * constructor
		 **/
		explicit CSmartPtr(
			T *i_Ptr = NULL /** Start address of heap memory.**/
		)
		{
			m_Counted = new CCounted(i_Ptr);
			m_Counted->Use();
		}

		/**
		 * copy constructor
		 **/
		CSmartPtr(
			const CSmartPtr<T> &i_Src /** Reference CSmartPtr.**/
		)
		{
			m_Counted = i_Src.m_Counted;
			m_Counted->Use();
		}

		/**
		 * destructor
		 **/
		~CSmartPtr()
		{
			m_Counted->Dismiss();
		}

		/**
		 * Assignment operator.
		 * @returns
		 * Reference to itself.
		 **/
		CSmartPtr<T> &operator=(
			T *i_Ptr /** Start address of heap memory.**/
		)
		{
			m_Counted->Dismiss();
			m_Counted = new CCounted(i_Ptr);
			m_Counted->Use();
			return *this;
		}

		/**
		 * Assignment operator.
		 * @returns
		 * Reference to itself.
		 **/
		CSmartPtr<T> &operator=(
			const CSmartPtr<T> &i_Src /** Reference CSmartPtr.**/
		)
		{
			m_Counted->Dismiss();
			m_Counted = i_Src.m_Counted;
			m_Counted->Use();
			return *this;
		}
		/**
		 *compare < operator. Will call the operator for the data itself.
		 * @returns
		 * true if this object is'less than' (in terms of the defined data-operator)
		 **/
		bool operator<(
			const CSmartPtr<T> &i_Src /** Reference CSmartPtr.**/
		)
		{
			return *get() < *(i_Src.get());
		}

		/**
		 * Operators and functions to access the heap memory.
		 * @returns
		 * Address or value of dynamic object.
		 **/
		operator T &() const { return m_Counted->operator T &(); }
		operator T *() const { return m_Counted->operator T *(); }
		T *operator->() const { return m_Counted->operator->(); }
		T *Get() const { return m_Counted->operator->(); }

		/**
		 *Only for easier conversion of former auto_ptr's.
		 *
		 **/

		T *get() const { return m_Counted->operator->(); }

		/**
		 * Returns heap memory address and set sets own copy of the address to NULL to prevent deletion.
		 * @returns
		 * 	Heap memory address.
		 **/

		T *Release()
		{
			return m_Counted->Release();
		}

		/**
		 * Casts a Util::CSmartPtr<F> object to a Util:CSmartPtr<T> object.
		 * Note that this will actually release the original and set it to NULL.
		 * @returns
		 * Util::CSmartPtr<T>.
		 * - the cast operation is not possible because the classes are not suitably related, or
		 * - the original CSmartPtr contains a NULL pointer.
		 **/
		template <class F>
		inline static Util::CSmartPtr<T> Cast(
			Util::CSmartPtr<F> i_From)
		{
			T *to = NULL;
			if (dynamic_cast<T *>(i_From.Get()))
				to = dynamic_cast<T *>(i_From.Release());
			return Util::CSmartPtr<T>(to);
		}
	};

	/**
	 * Casts a Util::CSmartPtr<CFrom> object to a Util:CSmartPtr<CTo> object.
	 * Note that this will actually release the original and set it to NULL.
	 * @returns
	 * Util::CSmartPtr<T>.
	 * - the cast operation is not possible because the classes are not suitably related, or
	 * - the original CSmartPtr contains a NULL pointer.
	 * NOTE:
	 * Function exists only for backward compatibility.
	 * Rather use the CSmartPtr<CTo>::Cast() function directly!
	 **/
	template <class CTo, class CFrom>
	inline Util::CSmartPtr<CTo> SmartPtrCast(
		Util::CSmartPtr<CFrom> i_From)
	{
		try
		{
			return Util::CSmartPtr<CTo>::Cast(i_From);
		}
		catch (...)
		{
			LOGCATCHANDTHROW;
		}
	}

}

#endif