/*

* 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 search algorithm

*

*/

#ifndef XNBREADTHFIRSTTREEITERATOR_H

#define XNBREADTHFIRSTTREEITERATOR_H

//  INCLUDES

#include <e32base.h>

#include <e32cmn.h>

#include "xnchilditerator.h"

// Constants

/** 

 * Queue granularity value

 */

const TInt KMemoryAlocQ = 64;

template < class T >

    class CXnBreadthFirstTreeIterator: public CBase, public MXnChildIterator

    {

public:

    /**

     * Two-phased constructor.

     * @param aStartNode object to iterate over

     * @param aDepth with default parameter value 0.

     */

    static CXnBreadthFirstTreeIterator< T >* NewL( T& aStartNode,

        TUint aDepth = 0 );

    /**

     * Destructor.

     */

    virtual ~CXnBreadthFirstTreeIterator();

    /**

     * 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. 

     */

    CXnBreadthFirstTreeIterator( T* aStartNode, TUint aDepth = 0 );

    /**

     * 2nd phase constructor. 

     */

    void ConstructL();

private: //Data

    // Queue

    RPointerArray< T > iQueue;

    // Object to iterate over

    T* iStart;

    // Current object

    T* iCurrent;

    // Tree depth

    TUint iDepth;

    // Current index 

    TUint iIndex;

    };

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

// CXnBreadthFirstTreeIterator< T >::NewL()

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

//

template< class T > CXnBreadthFirstTreeIterator< T >*

    CXnBreadthFirstTreeIterator< T >::NewL( T& aStartNode, TUint aDepth )

    {

    CXnBreadthFirstTreeIterator< T >* p = 

        new ( ELeave )CXnBreadthFirstTreeIterator< T >( &aStartNode,

            aDepth );

    CleanupStack::PushL( p );

    p->ConstructL();

    CleanupStack::Pop();

    return p;

    }

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

// XnBreadthFirstTreeIterator< T >::CXnBreadthFirstTreeIterator()

// C++ default constructor

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

//

template< class T >

    CXnBreadthFirstTreeIterator< T >::CXnBreadthFirstTreeIterator(

    T* aStartNode, TUint aDepth ) : iQueue( KMemoryAlocQ ), iStart( 

    aStartNode ),iCurrent( aStartNode ),iDepth( aDepth )

    {

    }

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

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

// C++ default destructor.

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

//

template< class T >

    CXnBreadthFirstTreeIterator< T >::~CXnBreadthFirstTreeIterator()

    { 

    iQueue.Close();

    }

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

// CXnBreadthFirstTreeIterator< T >::ConstructL()

// Symbian 2nd phase constructor can leave.

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

//

template< class T >

    void CXnBreadthFirstTreeIterator< T >::ConstructL()

    {

    iQueue.AppendL( iStart );

    iIndex = 0; 

    }

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

// CXnBreadthFirstTreeIterator< T >::NextL()

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

//

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

    { 

    if( iQueue.Count() )

        {

        // Dequeue

        if ( !iDepth )

            {

            iCurrent = iQueue[0];

            iQueue.Remove(0);

            }

        RPointerArray< T > currentChildNodes = iCurrent->ChildrenL();

        TInt currentChildCount( currentChildNodes.Count() );

        if ( iDepth )

            {

             if ( (iIndex + 1) < currentChildCount )

                 {

                     for ( TUint tmp = iIndex; (tmp + 1) < currentChildCount; )

                         {

                         T* tmpObject = currentChildNodes[++tmp];

                         iIndex = tmp;

                         currentChildNodes.Reset(); 

                         return tmpObject;

                         }

                  }

             else

                 {

                 currentChildNodes.Reset();

                 return NULL;

                  }

            }      

        // Enqueue

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

            {

            iQueue.AppendL( currentChildNodes[i] );

            }

        currentChildNodes.Reset();

        }

    else

        {

        iCurrent = NULL;

        iQueue.Reset();

        iQueue.AppendL( iStart );

        }

    return iCurrent;

    }

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

// CXnBreadthFirstTreeIterator< T >::Value()

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

//

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

    {

    return iCurrent;

    }

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

// CXnBreadthFirstTreeIterator< T >::PreviousL()

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

//

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

    {

    return NULL;

    }

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

// CXnBreadthFirstTreeIterator< T >::Index()

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

//

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

    {

    return 0;

    }

#endif    // CXNBREADTHFIRSTTREEITERATOR_H

// End of File