/*

* Copyright (c) 2002-2004 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:  Iterates over a tree, breadth first

*

*/

#ifndef XNNODEBREADTHFIRSTITERATOR_H

#define XNNODEBREADTHFIRSTITERATOR_H

#include <e32base.h>

#include <e32cmn.h>

#include "xnchilditerator.h"

// Constants

/** 

 * Queue granularity value

 */

const TInt KMemoryAloc = 128;

template< class T > class CXnNodeBreadthFirstIterator : public CBase,

    public MXnChildIterator

    {

public:

    /**

    * Two-phased constructor.

    * @param aStartNode Object to iterate over

    */

    static CXnNodeBreadthFirstIterator< T >* NewL( T& aStartNode );

    /**

    * Destructor.

    */

    virtual ~CXnNodeBreadthFirstIterator();

    /**

    * Get the next iterator value.

    * @return Next object or NULL if no more values. 

    */

    T* NextL();

    /**

    * Get the current iterator value.

    * @return Current object 

    */     

    T* Value();

    /**

    * Get the previous iterator value. Obsolete!

    * @return NULL 

    */

    T* PreviousL();

    /**

    * Get the current iterator index. Obsolete!

    * @return value 0

    */

    TUint Index() const;

protected:

    /**

    * C++ default constructor. 

    */

    CXnNodeBreadthFirstIterator( T* aStartNode );

    /**

    * 2nd phase constructor. 

    */

    void ConstructL();

private:   

    // Queue

    RPointerArray< T > iQueue;

    // Object to iterate over

    T* iStart;   

    // Current object

    T* iCurrent;

    };

// -----------------------------------------------------------------------------

// CXnNodeBreadthFirstIterator< T >::NewL()

// -----------------------------------------------------------------------------

//

template< class T > CXnNodeBreadthFirstIterator< T >* 

    CXnNodeBreadthFirstIterator< T >::NewL( T& aStartNode )

    {

    CXnNodeBreadthFirstIterator< T >* p = 

        new ( ELeave )CXnNodeBreadthFirstIterator< T >( &aStartNode );

    CleanupStack::PushL( p );

    p->ConstructL();

    CleanupStack::Pop();

    return p;

    }

// -----------------------------------------------------------------------------

// CXnNodeBreadthFirstIterator< T >::CXnNodeBreadthFirstIterator()

// C++ default constructor

// -----------------------------------------------------------------------------

//

template< class T >

    CXnNodeBreadthFirstIterator < T >::CXnNodeBreadthFirstIterator(

    T* aStartNode ): iStart( aStartNode ), iCurrent( aStartNode ),

    iQueue( KMemoryAloc )

    {

    }

// -----------------------------------------------------------------------------

//  CXnNodeBreadthFirstIterator< T >::~CXnNodeBreadthFirstIterator()

//  C++ default destructor.     

// -----------------------------------------------------------------------------

//     

template< class T >

    CXnNodeBreadthFirstIterator< T >::~CXnNodeBreadthFirstIterator()

    {

    iQueue.Close();

    }

// -----------------------------------------------------------------------------

// CXnNodeBreadthFirstIterator< T >::ConstructL()

// Symbian 2nd phase constructor can leave.

// -----------------------------------------------------------------------------

//

template< class T > void CXnNodeBreadthFirstIterator< T >::ConstructL()

    {

    iQueue.AppendL( iStart );

    }

// -----------------------------------------------------------------------------

// CXnNodeBreadthFirstIterator< T >::NextL()

// -----------------------------------------------------------------------------

//

template< class T > T* CXnNodeBreadthFirstIterator< T >::NextL()

    {

    if( iQueue.Count() )

        {

        // Dequeue

        iCurrent = iQueue[0];

        iQueue.Remove(0);

        RPointerArray< T >& currentChildNodes = iCurrent->Children();

        TInt currentChildCount( currentChildNodes.Count() );

        // Enqueue

        for( TInt i = 0; i < currentChildCount; ++i )

            {

            iQueue.AppendL( currentChildNodes[i] );

            }

        }

    else

        {

        iCurrent = NULL;

        iQueue.Reset();

        iQueue.AppendL( iStart );

        }

    return iCurrent;

    }

// -----------------------------------------------------------------------------

// CXnNodeBreadthFirstIterator< T >::Value()

// -----------------------------------------------------------------------------

//

template< class T > T* CXnNodeBreadthFirstIterator< T >::Value()

    {

    return iCurrent;

    }

// -----------------------------------------------------------------------------

// CXnNodeBreadthFirstIterator< T >::PreviousL()

// -----------------------------------------------------------------------------

//

template< class T > T* CXnNodeBreadthFirstIterator< T >::PreviousL()

    {

    return NULL;

    }

// -----------------------------------------------------------------------------

// CXnNodeBreadthFirstIterator< T >::Index()

// -----------------------------------------------------------------------------

//

template< class T > TUint CXnNodeBreadthFirstIterator< T >::Index() const

    {

    return 0;

    }

#endif    //CXNNODEBREADTHFIRSTITERATOR_H

// End of File