text: /*
  -----------------------------------------------------------------------------
  This source file is part of OGRE
      (Object-oriented Graphics Rendering Engine)
  For the latest info, see http://www.ogre3d.org/
  
  Copyright (c) 2000-2013 Torus Knot Software Ltd
  
  Permission is hereby granted, free of charge, to any person obtaining a copy
  of this software and associated documentation files (the "Software"), to deal
  in the Software without restriction, including without limitation the rights
  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  copies of the Software, and to permit persons to whom the Software is
  furnished to do so, subject to the following conditions:
  
  The above copyright notice and this permission notice shall be included in
  all copies or substantial portions of the Software.
  
  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  THE SOFTWARE.
  -----------------------------------------------------------------------------
  */
  #ifndef __SharedPtr_H__
  #define __SharedPtr_H__
  
  #include "OgrePrerequisites.h"
  #include "OgreAtomicScalar.h"
  
  namespace Ogre {
  	/** \addtogroup Core
  	*  @{
  	*/
  	/** \addtogroup General
  	*  @{
  	*/
  
  	/// The method to use to free memory on destruction
  	enum SharedPtrFreeMethod
  	{
  		/// Use OGRE_DELETE to free the memory
  		SPFM_DELETE,
  		/// Use OGRE_DELETE_T to free (only MEMCATEGORY_GENERAL supported)
  		SPFM_DELETE_T,
  		/// Use OGRE_FREE to free (only MEMCATEGORY_GENERAL supported)
  		SPFM_FREE
  	};
  
      struct SharedPtrInfo {
          inline SharedPtrInfo()
              : useCount(1)
          {}
  
          virtual ~SharedPtrInfo() {}
  
          AtomicScalar<unsigned>  useCount;
      };
  
  	template <class T>
  	class SharedPtrInfoDelete : public SharedPtrInfo
  	{
          T* mObject;
      public:
          inline SharedPtrInfoDelete(T* o) : mObject(o) {}
  
  		virtual ~SharedPtrInfoDelete()
  		{
  			OGRE_DELETE mObject;
  		}
  	};
  
  	template <class T>
  	class SharedPtrInfoDeleteT : public SharedPtrInfo
  	{
          T* mObject;
      public:
          inline SharedPtrInfoDeleteT(T* o) : mObject(o) {}
  
  		virtual ~SharedPtrInfoDeleteT()
  		{
  			OGRE_DELETE_T(mObject, T, MEMCATEGORY_GENERAL);
  		}
  	};
  
  	template <class T>
  	class SharedPtrInfoFree : public SharedPtrInfo
  	{
          T* mObject;
      public:
          inline SharedPtrInfoFree(T* o) : mObject(o) {}
  
  		virtual ~SharedPtrInfoFree()
  		{
  			OGRE_FREE(mObject, MEMCATEGORY_GENERAL);
  		}
  	};
  
  	/** Reference-counted shared pointer, used for objects where implicit destruction is
          required.
      @remarks
          This is a standard shared pointer implementation which uses a reference
          count to work out when to delete the object.
  	@par
  		If OGRE_THREAD_SUPPORT is defined to be 1, use of this class is thread-safe.
      */
  	template<class T> class SharedPtr
  	{
          template<typename Y> friend class SharedPtr;
  	protected:
          /* DO NOT ADD MEMBERS TO THIS CLASS!
           *
           * The average Ogre application has *thousands* of them. Every extra
           * member causes extra memory use in general, and causes extra padding
           * to be added to a multitude of structures.
           *
           * Everything you need to do can be acomplished by creatively working
           * with the SharedPtrInfo object.
           *
           * There is no reason for this object to ever have more than two members.
           */
  
  		T*             pRep;
          SharedPtrInfo* pInfo;
  
          SharedPtr(T* rep, SharedPtrInfo* info) : pRep(rep), pInfo(info)
  		{
  		}
  
  	public:
  		/** Constructor, does not initialise the SharedPtr.
  			@remarks
  				<b>Dangerous!</b> You have to call bind() before using the SharedPtr.
  		*/
  		SharedPtr() : pRep(0), pInfo(0)
          {}
  
      private:
          static SharedPtrInfo* createInfoForMethod(T* rep, SharedPtrFreeMethod method)
          {
              switch(method) {
                  case SPFM_DELETE:   return OGRE_NEW_T(SharedPtrInfoDelete<T>,  MEMCATEGORY_GENERAL) (rep);
                  case SPFM_DELETE_T: return OGRE_NEW_T(SharedPtrInfoDeleteT<T>, MEMCATEGORY_GENERAL) (rep);
                  case SPFM_FREE:     return OGRE_NEW_T(SharedPtrInfoFree<T>,    MEMCATEGORY_GENERAL) (rep);
              }
              assert(!"Bad method");
              return 0;
          }
      public:
  
  		/** Constructor.
  		@param rep The pointer to take ownership of
  		@param inFreeMethod The mechanism to use to free the pointer
  		*/
          template< class Y>
  		explicit SharedPtr(Y* rep, SharedPtrFreeMethod inFreeMethod = SPFM_DELETE)
              : pRep(rep)
              , pInfo(rep ? createInfoForMethod(rep, inFreeMethod) : 0)
  		{
  		}
  
  		SharedPtr(const SharedPtr& r)
              : pRep(r.pRep)
              , pInfo(r.pInfo)
  		{
              if (pRep)
              {
                  ++pInfo->useCount;
              }
  		}
  
  		SharedPtr& operator=(const SharedPtr& r) {
  			if (pRep == r.pRep)
              {
                  assert(pInfo == r.pInfo);
  				return *this;
              }
  			// Swap current data into a local copy
  			// this ensures we deal with rhs and this being dependent
  			SharedPtr<T> tmp(r);
  			swap(tmp);
  			return *this;
  		}
  
  		/* For C++11 compilers, use enable_if to only expose functions when viable
           *
           * MSVC 2012 and earlier only claim conformance to C++98. This is fortunate,
           * because they don't support default template parameters
           */
  #if __cplusplus >= 201103L
          template<class Y,
              class = typename std::enable_if<std::is_convertible<Y*, T*>::value>::type>
  #else
          template<class Y>
  #endif
          SharedPtr(const SharedPtr<Y>& r)
              : pRep(r.getPointer())
              , pInfo(r.pInfo)
  		{
              if (pRep)
              {
                  ++pInfo->useCount;
              }
          }
  
  #if __cplusplus >= 201103L
          template<class Y,
                   class = typename std::enable_if<std::is_assignable<T*, Y*>::value>::type>
  #else
          template<class Y>
  #endif
          SharedPtr& operator=(const SharedPtr<Y>& r)
          {
  			if (pRep == r.pRep)
  				return *this;
  			// Swap current data into a local copy
  			// this ensures we deal with rhs and this being dependent
  			SharedPtr<T> tmp(r);
  			swap(tmp);
  			return *this;
  		}
  
  		~SharedPtr() {
              release();
  		}
  
          template<typename Y>
          inline SharedPtr<Y> staticCast() const
          {
              if(pRep) {
                  ++pInfo->useCount;
  				return SharedPtr<Y>(static_cast<Y*>(pRep), pInfo);
              } else return SharedPtr<Y>();
          }
  
          template<typename Y>
          inline SharedPtr<Y> dynamicCast() const
          {
              if(pRep) {
                  Y* rep = dynamic_cast<Y*>(pRep);
                  ++pInfo->useCount;
  				return SharedPtr<Y>(rep, pInfo);
              } else return SharedPtr<Y>();
          }
  
  		inline T& operator*() const { assert(pRep); return *pRep; }
  		inline T* operator->() const { assert(pRep); return pRep; }
  		inline T* get() const { return pRep; }
          inline SharedPtrInfo* getPtrInfo() const { return pInfo; }
  
  		/** Binds rep to the SharedPtr.
  			@remarks
  				Assumes that the SharedPtr is uninitialised!
  
              @warning
                  The object must not be bound into a SharedPtr elsewhere
  		*/
  		void bind(T* rep, SharedPtrFreeMethod inFreeMethod = SPFM_DELETE) {
  			assert(!pRep && !pInfo);
  			pInfo = createInfoForMethod(rep, inFreeMethod);
  			pRep = rep;
  		}
  
  		inline bool unique() const { assert(pInfo && pInfo->useCount.get()); return pInfo->useCount.get() == 1; }
  		inline unsigned int useCount() const { assert(pInfo && pInfo->useCount.get()); return pInfo->useCount.get(); }
          inline void setUseCount(unsigned value) { assert(pInfo); pInfo->useCount = value; }
  
  		inline T* getPointer() const { return pRep; }
  
  		inline bool isNull(void) const { return pRep == 0; }
  
          inline void setNull(void) {
  			if (pRep)
  			{
  				release();
  			}
          }
  
      protected:
  
          inline void release(void)
          {
              if (pRep)
              {
                  assert(pInfo);
                  if(--pInfo->useCount == 0)
                      destroy();
              }
  
              pRep = 0;
              pInfo = 0;
          }
  
          /** IF YOU GET A CRASH HERE, YOU FORGOT TO FREE UP POINTERS
           BEFORE SHUTTING OGRE DOWN
           Use setNull() before shutdown or make sure your pointer goes
           out of scope before OGRE shuts down to avoid this. */
          inline void destroy(void)
          {
              assert(pRep && pInfo);
              OGRE_DELETE_T(pInfo, SharedPtrInfo, MEMCATEGORY_GENERAL);
          }
  
  		inline void swap(SharedPtr<T> &other)
  		{
  			std::swap(pRep, other.pRep);
  			std::swap(pInfo, other.pInfo);
  		}
  	};
  
  	template<class T, class U> inline bool operator==(SharedPtr<T> const& a, SharedPtr<U> const& b)
  	{
  		return a.get() == b.get();
  	}
  
  	template<class T, class U> inline bool operator!=(SharedPtr<T> const& a, SharedPtr<U> const& b)
  	{
  		return a.get() != b.get();
  	}
  
  	template<class T, class U> inline bool operator<(SharedPtr<T> const& a, SharedPtr<U> const& b)
  	{
  		return std::less<const void*>()(a.get(), b.get());
  	}
  	/** @} */
  	/** @} */
  }
  
  #endif
  