/*

* 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, depth first

*

*/

#ifndef XNDEPTHFIRSTTREEITERATOR_H

#define XNDEPTHFIRSTTREEITERATOR_H

//  INCLUDES

#include <e32base.h>

#include "xnchilditerator.h"

// Constants

/** 

 * Queue granularity value

 */

const TInt KMemoryAlocS = 64;

template < class T >

    class CXnDepthFirstTreeIterator: public CBase, public MXnChildIterator

    {

public:

    /**

    * Two-phased constructor.

    * @param aStartNode Object to iterate over

    */

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

    /**

    * Destructor.

    */

    virtual ~CXnDepthFirstTreeIterator();

    /**

    * 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;

    /**

    * Get the current iterator level in the tree.

    * @return current level

    */

    TUint Level() const;

protected:

    CXnDepthFirstTreeIterator( T* aStartNode );

    void ConstructL();

private:

    //Stack

    RPointerArray< T > iStack;

    //Object to iterate over

    T* iStart;

    // Current object

    T* iCurrent;

    };

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

// CXnDepthFirstTreeIterator< T >::NewL()

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

//

template< class T > CXnDepthFirstTreeIterator< T >*

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

    {

    CXnDepthFirstTreeIterator<T>* self = 

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

    CleanupStack::PushL( self );

    self->ConstructL();

    CleanupStack::Pop();

    return self;

    }

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

// CXnDepthFirstTreeIterator< T >::CXnDepthFirstTreeIterator()

// C++ default constructor

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

//

template< class T > CXnDepthFirstTreeIterator< T >::CXnDepthFirstTreeIterator(

    T* aStartNode ):

    iStart( aStartNode ),

    iCurrent( aStartNode ),

    iStack( KMemoryAlocS )

    {

    }

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

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

//  C++ default destructor.  

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

//  

template< class T >

    CXnDepthFirstTreeIterator< T >::~CXnDepthFirstTreeIterator()

    {

    iStack.Close();

    }

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

// CXnDepthFirstTreeIterator< T >::ConstructL()

// Symbian 2nd phase constructor can leave.

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

//

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

    {

    iStack.AppendL( iStart );

    }

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

// CXnDepthFirstTreeIterator< T >::NextL()

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

//

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

    {

    if( iStack.Count() )

        {

        // Pop

        TInt topIndex( iStack.Count() - 1 );

        iCurrent = iStack[topIndex];

        iStack.Remove( topIndex );

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

        TInt currentChildCount( currentChildNodes.Count() );

        // Push left most child to top

        for( TInt i = currentChildCount - 1; i >= 0; --i )

            {

            iStack.AppendL( currentChildNodes[i] );

            }

        }

    else

        {

        iCurrent = NULL;

        iStack.Reset();

        iStack.AppendL( iStart );

        }

    return iCurrent;

    }

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

// CXnDepthFirstTreeIterator< T >::Value()

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

//

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

    {

    return iCurrent;

    }

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

// CXnDepthFirstTreeIterator< T >::PreviousL()

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

//

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

    {

    return NULL;

    }

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

// CXnDepthFirstTreeIterator< T >::Index()

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

//

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

    {

    return 0;

    }

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

// CXnDepthFirstTreeIterator< T >::Level()

// Get the current iterator level in the tree.

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

template< class T > TUint CXnDepthFirstTreeIterator< T >::Level() const

    {

    return iStack.Count();

    }

#endif    // CXNDEPTHFIRSTTREEITERATOR_H

// End of File