// Copyright (c) 2004-2009 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:

// node.h - structures to hold node information

//

#ifndef __NODE_H__

#define __NODE_H__

/**

@file node.h

DNS Cache (internal part of the DNS cache implementation)

@internalComponent	Domain Name Resolver

*/

#include "record.h"

class CDndEngine;

class CDndNode;

// Implement a node list ONLY for CDndNode, not for anyone else

class TDndNodeList : public TDblQue<CDndNode>

	{

	friend class CDndNode;

	// only to initialize the offset in the TDblQue head

	TDndNodeList();

	CDndNode *Find(const TNodeLabel &aLabel);	//< Find the node by label

	void AddNode(CDndNode &aNode);				//< Add node to the list

	void DeleteNode(CDndNode *const aNode);		//< Delete node from the list

	void Print(CDndEngine &aControl);			//< Prints out the contents of the node-list (DEBUG only)

	};

class CDndNode : public CBase

	{

	friend class TDndNodeList;

	friend class CDndRecord;

	// constructors and destructor

protected:

	CDndNode(CDndNode *const aParent, const TInt aLevel, const TNodeLabel &aLabel);

	~CDndNode();

public:

	// Locate (and create path) to a node identified by a domain name, and find (or create) a record matching the type and class

	CDndRecord *FindL(

		const TDesC8 &aName,

		const TBool aFlag,

		const EDnsQType aType,

		const EDnsQClass aClass,

		TDndRecordLRU &aLRU,

		const TTime &aReqTime);

	// Prints out the contents of this node and all its descendants

	void Print(CDndEngine &aControl);

protected:

	// Return TRUE, if node has no children and no records

	inline TBool IsEmpty() const { return iRecordList.IsEmpty() && iChildren.IsEmpty(); }

private:	

	static const TInt iOffset;		//< For the linked list

	// Unconditionally delete a record from the node

	void DeleteRecord(CDndRecord *const aRecord);

	// Delete node path, if it has no records and no child nodes

	void Cleanup();

	// Delete a child from the node (which, must be a child of this node!)

	void DeleteNode(CDndNode *const aNode);

	CDndNode *const iParent;	//< Back link to the parent node (except at root = NULL)

	const TInt iLevel;			//< Depth of the node in the tree

	const TNodeLabel iLabel;	//< Label of the node.

	TDblQueLink iDlink;			//< Siblings chain (nodes on same level)		

	TDndRecordList iRecordList;	//< List of Records with this node's name.

	TDndNodeList iChildren;		//< Children are implemented as a linked list of nodes

	};

#endif