/*

* Copyright (c) 2000-2009 Nokia Corporation and/or its subsidiary(-ies).

* All rights reserved.

* This component and the accompanying materials are made available

* under the terms of "Eclipse Public License v1.0"

* which accompanies this distribution, and is available

* at the URL "http://www.eclipse.org/legal/epl-v10.html".

*

* Initial Contributors:

* Nokia Corporation - initial contribution.

*

* Contributors:

*

* Description: 

*

*/

#ifndef UNIQUEINSTANCEIMPL_H_

#define UNIQUEINSTANCEIMPL_H_

#include "UniqueInstance.h"

namespace UniqueInstance

{

/**

@internalComponent

*/

void DestroyRUniqueInstance(void* runique);

/**

 * Reference-counted object.

 *

 * @internalComponent

 * @since App-frameworks6.1

 */

struct SElement

	{

	TInt iRefCount;

	void* iObject;

	};

/**

 * Skip list holding sorted, reference counted objects

 *

 * @internalComponent

 * @since App-frameworks6.1

 */

class RSkipList

	{

public:

	struct TSection

		{

		TSection* iLinks[1];

		SElement iElement;

		};

	RSkipList& operator=(const RSkipList&);

	RSkipList(const RSkipList&);

	void TestLinks(TSection* aStart, TSection* aEnd, TInt aLink) const;

	RSkipList() : iSentinel(0), iCompare(0) {}

	~RSkipList();

	void Open(TCompareFn* aCompare, TInt aMaxLinks);

	void Close();

	/**

	 * Adds an element only if it already exists, otherwise returns 0

	 */

	SElement* AddExisting(void* aElt);

	/**

	 * Adds a new element. aNewElt must not already have an equivalent in this

	 * skip list.

	 */

	SElement* AddNewL(void* aNewElt);

	/**

	 * Removes the element, no matter what its reference count is. Return a pointer

	 * to the object, which is now no longer owned.

	 */

	void* Remove(void* aNoLongerNeeded);

	/**

	 * Returns true iff skip list has no elements.

	 */

	TBool IsEmpty() const;

	/**

	 * Runs tests on the integrity of the skip list.

	 * Returns the number of elements in the list.

	 */

	TInt Test() const;

private:

	TSection*	iSentinel;

	TInt		iLinkCount;

	TCompareFn*	iCompare;

	TSection** FirstLink() const;

	TInt GenerateNumLinks() const;

	};

}

/**

 * Implements the unique instance repository behaviour

 *

 * @internalComponent

 * @since App-frameworks6.1

 */

NONSHARABLE_CLASS(UniqueInstance::CRepositoryImpl) : public CBase

	{

public:

	CRepositoryImpl(TCompareFn* aCompare, TDeleteFn* aDelete, TCopyFnL* aCopyL,

		TInt aObjectSize);

	~CRepositoryImpl();

	void ConstructL(TInt aMaxLinks);

	/**

	 * Adds aElt to the list, passing ownership.

	 */

	SElement*	InsertOrIncL(void* aElt);

	/**

	 * Adds aElt to the list with the caller retaining ownership.

	 */

	SElement*	IncOrCopyL(void* aElt);

	/**

	 * Deletes from the list. aNoLongerNeeded points to an element of the list.

	 */

	void		DeleteOrDec(UniqueInstance::SElement* aNoLongerNeeded);

	/**

	 * Removes from the list, passing ownership back to the caller.

	 */

	void*		DetatchOrCopyL(UniqueInstance::SElement* aWritableCopyNeeded);

	/**

	 * Returns a prototype null element. Ownership is retained.

	 */

	SElement*	NullElement();

	/**

	 * Compares the element pointer passed against the prototype null element.

	 */

	TBool		IsNull(SElement* a) const;

	/**

	 * Runs an integrity check. Panics on failure.

	 */

	void		Test() const;

private:

	TCompareFn*	iCompare;

	TDeleteFn*	iDelete;

	TCopyFnL*	iCopyL;

	TInt		iObjectSize;

	SElement	iNullElement;

	RSkipList	iSkipList;

	};

#endif	// UNIQUEINSTANCEIMPL_H_