/* $Id: avl_Destroy.cpp.h 91108 2013-12-05 12:39:28Z fmehnert $ */
/** @file
 * kAVLDestroy - Walk the tree calling a callback to destroy all the nodes.
 */

/*
 * Copyright (C) 1999-2011 knut st. osmundsen (bird-src-spam@anduin.net)
 *
 * This file is part of VirtualBox Open Source Edition (OSE), as
 * available from http://www.virtualbox.org. This file is free software;
 * you can redistribute it and/or modify it under the terms of the GNU
 * General Public License (GPL) as published by the Free Software
 * Foundation, in version 2 as it comes in the "COPYING" file of the
 * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
 * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
 *
 * The contents of this file may alternatively be used under the terms
 * of the Common Development and Distribution License Version 1.0
 * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
 * VirtualBox OSE distribution, in which case the provisions of the
 * CDDL are applicable instead of those of the GPL.
 *
 * You may elect to license modified versions of this file under the
 * terms and conditions of either the GPL or the CDDL or both.
 */

#ifndef _kAVLDestroy_h_
#define _kAVLDestroy_h_

/**
 * Destroys the specified tree, starting with the root node and working our way down.
 *
 * @returns 0 on success.
 * @returns Return value from callback on failure. On failure, the tree will be in
 *          an unbalanced condition and only further calls to the Destroy should be
 *          made on it. Note that the node we fail on will be considered dead and
 *          no action is taken to link it back into the tree.
 * @param   ppTree          Pointer to the AVL-tree root node pointer.
 * @param   pfnCallBack     Pointer to callback function.
 * @param   pvUser          User parameter passed on to the callback function.
 */
KAVL_DECL(int) KAVL_FN(Destroy) (PPKAVLNODECORE ppTree,
				 PKAVLCALLBACK pfnCallBack, void *pvUser)
{
	unsigned cEntries;
	PKAVLNODECORE apEntries[KAVL_MAX_STACK];
	int rc;

	if (*ppTree == KAVL_NULL)
		return VINF_SUCCESS;

	cEntries = 1;
	apEntries[0] = KAVL_GET_POINTER(ppTree);
	while (cEntries > 0) {
		/*
		 * Process the subtrees first.
		 */
		PKAVLNODECORE pNode = apEntries[cEntries - 1];
		if (pNode->pLeft != KAVL_NULL)
			apEntries[cEntries++] = KAVL_GET_POINTER(&pNode->pLeft);
		else if (pNode->pRight != KAVL_NULL)
			apEntries[cEntries++] =
			    KAVL_GET_POINTER(&pNode->pRight);
		else {
#ifdef KAVL_EQUAL_ALLOWED
			/*
			 * Process nodes with the same key.
			 */
			while (pNode->pList != KAVL_NULL) {
				PKAVLNODECORE pEqual =
				    KAVL_GET_POINTER(&pNode->pList);
				KAVL_SET_POINTER(&pNode->pList,
						 KAVL_GET_POINTER_NULL(&pEqual->
								       pList));
				pEqual->pList = KAVL_NULL;

				rc = pfnCallBack(pEqual, pvUser);
				if (rc != VINF_SUCCESS)
					return rc;
			}
#endif

			/*
			 * Unlink the node.
			 */
			if (--cEntries > 0) {
				PKAVLNODECORE pParent = apEntries[cEntries - 1];
				if (KAVL_GET_POINTER(&pParent->pLeft) == pNode)
					pParent->pLeft = KAVL_NULL;
				else
					pParent->pRight = KAVL_NULL;
			} else
				*ppTree = KAVL_NULL;

			kASSERT(pNode->pLeft == KAVL_NULL);
			kASSERT(pNode->pRight == KAVL_NULL);
			rc = pfnCallBack(pNode, pvUser);
			if (rc != VINF_SUCCESS)
				return rc;
		}
	}			/* while */

	kASSERT(*ppTree == KAVL_NULL);

	return VINF_SUCCESS;
}

#endif
