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/* $Id: avl_RemoveNode.cpp.h $ */
/** @file
* kAVLRemove2 - Remove specific node (by pointer) from an AVL tree.
*/
/*
* Copyright (C) 2006-2023 Oracle and/or its affiliates.
*
* This file is part of VirtualBox base platform packages, as
* available from https://www.virtualbox.org.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation, in version 3 of the
* License.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, see <https://www.gnu.org/licenses>.
*
* The contents of this file may alternatively be used under the terms
* of the Common Development and Distribution License Version 1.0
* (CDDL), a copy of it is provided in the "COPYING.CDDL" file included
* in the VirtualBox 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.
*
* SPDX-License-Identifier: GPL-3.0-only OR CDDL-1.0
*/
/**
* Removes the specified node from the tree.
*
* @returns Pointer to the removed node (NULL if not in the tree)
* @param ppTree Pointer to the AVL-tree root structure.
* @param pNode Pointer to the node to be removed.
*
* @remark This implementation isn't the most efficient, but it's relatively
* short and easier to manage.
*/
KAVL_DECL(PKAVLNODECORE) KAVL_FN(RemoveNode)(PPKAVLNODECORE ppTree, PKAVLNODECORE pNode)
{
#ifdef KAVL_EQUAL_ALLOWED
/*
* Find the right node by key together with the parent node.
*/
KAVLKEY const Key = pNode->Key;
PKAVLNODECORE pParent = NULL;
PKAVLNODECORE pCurNode = KAVL_GET_POINTER_NULL(ppTree);
if (!pCurNode)
return NULL;
while (KAVL_NE(pCurNode->Key, Key))
{
pParent = pCurNode;
if (KAVL_G(pCurNode->Key, Key))
{
if (pCurNode->pLeft != KAVL_NULL)
pCurNode = KAVL_GET_POINTER(&pCurNode->pLeft);
else
return NULL;
}
else
{
if (pCurNode->pRight != KAVL_NULL)
pCurNode = KAVL_GET_POINTER(&pCurNode->pRight);
else
return NULL;
}
}
if (pCurNode != pNode)
{
/*
* It's not the one we want, but it could be in the duplicate list.
*/
while (pCurNode->pList != KAVL_NULL)
{
PKAVLNODECORE pNext = KAVL_GET_POINTER(&pCurNode->pList);
if (pNext == pNode)
{
if (pNode->pList != KAVL_NULL)
KAVL_SET_POINTER(&pCurNode->pList, KAVL_GET_POINTER(&pNode->pList));
else
pCurNode->pList = KAVL_NULL;
pNode->pList = KAVL_NULL;
return pNode;
}
pCurNode = pNext;
}
return NULL;
}
/*
* Ok, it's the one we want alright.
*
* Simply remove it if it's the only one with they Key, if there are
* duplicates we'll have to unlink it and insert the first duplicate
* in our place.
*/
if (pNode->pList == KAVL_NULL)
KAVL_FN(Remove)(ppTree, pNode->Key);
else
{
PKAVLNODECORE pNewUs = KAVL_GET_POINTER(&pNode->pList);
pNewUs->uchHeight = pNode->uchHeight;
if (pNode->pLeft != KAVL_NULL)
KAVL_SET_POINTER(&pNewUs->pLeft, KAVL_GET_POINTER(&pNode->pLeft));
else
pNewUs->pLeft = KAVL_NULL;
if (pNode->pRight != KAVL_NULL)
KAVL_SET_POINTER(&pNewUs->pRight, KAVL_GET_POINTER(&pNode->pRight));
else
pNewUs->pRight = KAVL_NULL;
if (pParent)
{
if (KAVL_GET_POINTER_NULL(&pParent->pLeft) == pNode)
KAVL_SET_POINTER(&pParent->pLeft, pNewUs);
else
KAVL_SET_POINTER(&pParent->pRight, pNewUs);
}
else
KAVL_SET_POINTER(ppTree, pNewUs);
}
return pNode;
#else
/*
* Delete it, if we got the wrong one, reinsert it.
*
* This ASSUMS that the caller is NOT going to hand us a lot
* of wrong nodes but just uses this API for his convenience.
*/
KAVLNODE *pRemovedNode = KAVL_FN(Remove)(pRoot, pNode->Key);
if (pRemovedNode == pNode)
return pRemovedNode;
KAVL_FN(Insert)(pRoot, pRemovedNode);
return NULL;
#endif
}
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