/*
 Copyright (c) 2008 TrueCrypt Developers Association. All rights reserved.

 Governed by the TrueCrypt License 3.0 the full text of which is contained in
 the file License.txt included in TrueCrypt binary and source code distribution
 packages.
*/

#ifndef TC_HEADER_Platform_SharedPtr
#define TC_HEADER_Platform_SharedPtr

#include <stdexcept>
#include "SharedVal.h"

#ifdef nullptr

namespace TrueCrypt
{
	template <class T>
	class SharedPtr 
	{
	public:
		explicit SharedPtr ()
			: Pointer (nullptr), UseCount (nullptr) { }

		explicit SharedPtr (T *pointer)
			: Pointer (pointer), UseCount (new SharedVal <uint64> (1)) { }

		SharedPtr (const SharedPtr &source)
		{
			CopyFrom (source);
		}

		~SharedPtr ()
		{
			Release();
		}

		SharedPtr &operator= (const SharedPtr &source)
		{
			if (&source == this)
				return *this;

			Release();
			CopyFrom (source);
			return *this;
		}

		bool operator == (const SharedPtr &other)
		{
			return get() == other.get();
		}

		bool operator != (const SharedPtr &other)
		{
			return get() != other.get();
		}

		T &operator* () const
		{
#ifdef DEBUG
			if (Pointer == nullptr)
				throw std::runtime_error (SRC_POS);
#endif
			return *Pointer;
		}

		T *operator-> () const
		{
#ifdef DEBUG
			if (Pointer == nullptr)
				throw std::runtime_error (SRC_POS);
#endif
			return Pointer;
		}

		operator bool () const
		{
			return Pointer != nullptr;
		}

		T *get () const
		{
			return Pointer;
		}

		void reset ()
		{
			Release();
		}

		void reset (T *pointer)
		{
			*this = SharedPtr (pointer);
		}

		uint64 use_count () const
		{
			if (!UseCount)
				return 0;

			return *UseCount;
		}

	protected:
		void CopyFrom (const SharedPtr &source)
		{
			Pointer = source.Pointer;
			UseCount = source.UseCount;
			
			if (UseCount)
				UseCount->Increment();
		}

		void Release ()
		{
			if (UseCount != nullptr)
			{
				if (UseCount->Decrement() == 0)
				{
					if (Pointer != nullptr)
						delete Pointer;
					delete UseCount;
				}

				Pointer = nullptr;
				UseCount = nullptr;
			}
		}

		T *Pointer;
		SharedVal <uint64> *UseCount;
	};

#ifdef shared_ptr
#undef shared_ptr
#endif
#define shared_ptr TrueCrypt::SharedPtr

#ifdef make_shared
#undef make_shared
#endif

	template <class T> shared_ptr <T> make_shared ()
	{
		return shared_ptr <T> (new T ());
	}

	template <class T, class A> shared_ptr <T> make_shared (const A &arg)
	{
		return shared_ptr <T> (new T (arg));
	}

#define make_shared TrueCrypt::make_shared

}

#endif // nullptr

#define make_shared_auto(typeName,instanceName) shared_ptr <typeName> instanceName (new typeName ())

#endif // TC_HEADER_Platform_SharedPtr
