/*

* Copyright (c) 2003-2009 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: 

* CFixedQueue Test module

*

*/

#ifndef CFixedQueue_H

#define CFixedQueue_H

// INCLUDES

#include <e32base.h>

// CONSTANTS

_LIT(KFixedQueuePanicText, "CFixedQueue<T>");

// CLASS DECLARATION

/**

 * Fixed size queue.

 * @param T type of objects in the queue. T must have accessible default 

 *          constructor and assignment operator.

 */

template<class T>

class CFixedQueue : public CBase

    {

    public:  // Constructors and destructor

        CFixedQueue();

        /**

         * Initializes a new fixed queue.

         * @param aSize maximum size of the queue.

         * @pre aSize > 0

         */

        void ConstructL(TInt aSize);

        /**

         * Destructor.

         */

        ~CFixedQueue();

    public:  // Interface

        /**

         * Returns the object at the head of this queue.

         * @pre !IsEmpty()

         */

        T& Head() const;

        /**

         * Pops the head off this queue. Does not deallocate memory.

         * @pre !IsEmpty()

         */

        void PopHead();

        /**

         * Returns true if this queue is empty

         */

        TBool IsEmpty() const;

        /**

         * Returns the number of objects in the queue.

         */

        TInt Count() const;

        /**

         * Pushes an object at the tail of the queue.

         * @return ETrue if succesful, EFalse if queue run out of space.

         */ 

        TBool Push(const T& aObj);

        /**

         * Empties this queue. Does not deallocate memory.

         */

        void Reset();

    private:  // Implementation

        enum TPanicCode

            {

            EPanicPreCond_ConstructL = 1,

            EPanicPreCond_Head,

            EPanicPreCond_PopHead,

            EPanicPreCond_Push,

            EPanicInvariant

            };

        static void Panic(TPanicCode aReason);

        __DECLARE_TEST;

    private:  // Data

        /// Own: circural queue array

        T* iQueueArray;

        /// Own: maximum size of queue

        TInt iQueueSize;

        /// Own: number of objects currently in the queue

        TInt iCount;

        /// Ref: head of queue

        T* iQueueHead;

        /// Ref: tail of queue

        T* iQueueTail;

    };

template<class T> inline

void CFixedQueue<T>::Panic(TPanicCode aReason)

    {

    User::Panic(KFixedQueuePanicText,aReason);

    }

template<class T> inline

CFixedQueue<T>::CFixedQueue()

    {

    // CBase::operator new resets memebers

    __TEST_INVARIANT;

    }

template<class T> inline

void CFixedQueue<T>::ConstructL(TInt aSize)

    {

    __TEST_INVARIANT;

    __ASSERT_ALWAYS(!iQueueArray, Panic(EPanicPreCond_ConstructL));

    __ASSERT_ALWAYS(aSize > 0, Panic(EPanicPreCond_ConstructL));

    iQueueArray = new(ELeave) T[aSize];

    iQueueSize = aSize;

    iCount = 0;

    iQueueHead = iQueueTail = iQueueArray;

    __TEST_INVARIANT;

    }

template<class T>

CFixedQueue<T>::~CFixedQueue()

    {

    __TEST_INVARIANT;

    delete [] iQueueArray;

    }

template<class T> inline

T& CFixedQueue<T>::Head() const

    {

    __TEST_INVARIANT;

    __ASSERT_ALWAYS(iCount > 0, Panic(EPanicPreCond_Head));

    return *iQueueHead;

    }

template<class T> inline

void CFixedQueue<T>::PopHead()

    {

    __TEST_INVARIANT;

    __ASSERT_ALWAYS(iCount > 0, Panic(EPanicPreCond_PopHead));

    ++iQueueHead;

    if (iQueueHead == iQueueArray+iQueueSize)

        {

        iQueueHead = iQueueArray;

        }

    --iCount;

    }

template<class T> inline

TBool CFixedQueue<T>::IsEmpty() const

    {

    __TEST_INVARIANT;

    return (iCount==0);

    }

template<class T> inline

TInt CFixedQueue<T>::Count() const

    {

    __TEST_INVARIANT;

    return iCount;

    }

template<class T> inline

TBool CFixedQueue<T>::Push(const T& aObj)

    {

    __TEST_INVARIANT;

    if (iCount < iQueueSize)

        {

        *iQueueTail = aObj;

        ++iQueueTail;

        if (iQueueTail == iQueueArray+iQueueSize)

            {

            iQueueTail = iQueueArray;

            }

        ++iCount;

        __TEST_INVARIANT;

        return ETrue;

        }

    else

        {

        return EFalse;

        }

    }

template<class T> inline

void CFixedQueue<T>::Reset()

    {

    __TEST_INVARIANT;

    iQueueTail = iQueueHead;

    iCount = 0;

    __TEST_INVARIANT;

    }

template<class T>

void CFixedQueue<T>::__DbgTestInvariant() const

    {

    if (!iQueueArray)

        {

        // Not initialised

        __ASSERT_ALWAYS(iQueueSize==0 && iCount==0, Panic(EPanicInvariant));

        __ASSERT_ALWAYS(!iQueueHead && !iQueueTail, Panic(EPanicInvariant));

        }

    else

        {

        // Initialised

        __ASSERT_ALWAYS(iQueueSize > 0, Panic(EPanicInvariant));

        __ASSERT_ALWAYS(iCount >= 0 && iCount <= iQueueSize, Panic(EPanicInvariant));

        __ASSERT_ALWAYS((iQueueHead >= iQueueArray) && (iQueueHead < iQueueArray+iQueueSize), 

            Panic(EPanicInvariant));

        __ASSERT_ALWAYS((iQueueTail >= iQueueArray) && (iQueueTail < iQueueArray+iQueueSize), 

            Panic(EPanicInvariant));

        }

    }

#endif

// End of File