// Copyright (c) 2006-2009 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:

//

/**

 @file

*/

#ifndef TCACHEDATTRIBUTE_H

#define TCACHEDATTRIBUTE_H

#include <e32base.h>

/**

This class hold an external attribute and its cache status and ability

*/

// cache ability

typedef enum 

	{

	ECacheUnknown, // Initial value of the caching ability

	ECacheDisabled, // Caching is disabled.

	ECacheEnabled, // Caching is enabled.

	ECacheLegacy // It is always assumed that cached value is up to date.

	} TCacheAbility;	

// cache status

typedef enum

	{

	ECacheDirty,	// no value cached

	ECacheClean		// a value is cached

	} TCacheStatus;

template <class T>

class TCachedAttribute

	{	

public:

	inline TCachedAttribute();

	inline const T& Value();

	inline void SetValue(const T& aValue);

	inline TCacheAbility CacheAbility() const;

	inline TCacheStatus CacheStatus() const;

	inline void SetCacheEnabled();

	inline void SetCacheDisabled();

	inline void SetCacheDirty();

	inline void SetCacheClean();

	inline TBool IsCacheValid() const;

protected:

	TCacheAbility iCacheAbility;

	TCacheStatus iCacheStatus;

	T iValue;

	};

/**

Constuctor : set the cache as Dirty

*/

template <class T>

TCachedAttribute<T>::TCachedAttribute()

	: iCacheAbility(ECacheUnknown), iCacheStatus(ECacheDirty) 

	{

	}

/**

Mark the cache status as enabled.

*/

template <class T>

void TCachedAttribute<T>::SetCacheEnabled()

	{

	iCacheAbility = ECacheEnabled;

	}

/**

Mark the cache status as disabled.

*/

template <class T>

void TCachedAttribute<T>::SetCacheDisabled()

	{

	iCacheAbility = ECacheDisabled;

	SetCacheDirty();

	}

/**

Mark the cache status as dirty

*/

template <class T>

void TCachedAttribute<T>::SetCacheDirty()

	{

	iCacheStatus = ECacheDirty;

	}

/**

Mark the cache status as clean

*/

template <class T>

void TCachedAttribute<T>::SetCacheClean()

	{

	iCacheStatus = ECacheClean;

	}

/**

Check if the cache is up to date

@return ETrue if cache is enabled and in clean state. EFalse otherwise.

*/

template <class T>

TBool TCachedAttribute<T>::IsCacheValid() const

	{

	return ( (iCacheAbility == ECacheEnabled) && (iCacheStatus == ECacheClean) );

	}

/**

Getter

@return the cache ability

*/

template <class T>

TCacheAbility TCachedAttribute<T>::CacheAbility() const

	{

	return iCacheAbility;

	}

/**

Getter

@return the cache status

*/

template <class T>

TCacheStatus TCachedAttribute<T>::CacheStatus() const

	{

	return iCacheStatus;

	}

/**

Getter

@return the attribute value

*/

template <class T>

const T& TCachedAttribute<T>::Value()

	{

	return iValue;

	}

/**

Setter: set the attribute value, mark the cache clean if it was enable

@param aValue the attribute value

*/

template <class T>

void TCachedAttribute<T>::SetValue(const T& aValue)

	{

	iValue = aValue;

	if (iCacheAbility == ECacheEnabled)

		iCacheStatus = ECacheClean;

	}

#endif // TCACHEDATTRIBUTE_H