| 1 | /* $Id: avl_GetBestFit.cpp.h 98103 2023-01-17 14:15:46Z vboxsync $ */
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| 2 | /** @file
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| 3 | * kAVLGetBestFit - Get Best Fit routine for AVL trees.
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| 4 | * Intended specially on heaps. The tree should allow duplicate keys.
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| 5 | *
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| 6 | */
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| 7 |
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| 8 | /*
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| 9 | * Copyright (C) 2006-2023 Oracle and/or its affiliates.
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| 10 | *
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| 11 | * This file is part of VirtualBox base platform packages, as
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| 12 | * available from https://www.virtualbox.org.
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| 13 | *
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| 14 | * This program is free software; you can redistribute it and/or
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| 15 | * modify it under the terms of the GNU General Public License
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| 16 | * as published by the Free Software Foundation, in version 3 of the
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| 17 | * License.
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| 18 | *
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| 19 | * This program is distributed in the hope that it will be useful, but
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| 20 | * WITHOUT ANY WARRANTY; without even the implied warranty of
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| 21 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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| 22 | * General Public License for more details.
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| 23 | *
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| 24 | * You should have received a copy of the GNU General Public License
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| 25 | * along with this program; if not, see <https://www.gnu.org/licenses>.
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| 26 | *
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| 27 | * The contents of this file may alternatively be used under the terms
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| 28 | * of the Common Development and Distribution License Version 1.0
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| 29 | * (CDDL), a copy of it is provided in the "COPYING.CDDL" file included
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| 30 | * in the VirtualBox distribution, in which case the provisions of the
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| 31 | * CDDL are applicable instead of those of the GPL.
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| 32 | *
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| 33 | * You may elect to license modified versions of this file under the
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| 34 | * terms and conditions of either the GPL or the CDDL or both.
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| 35 | *
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| 36 | * SPDX-License-Identifier: GPL-3.0-only OR CDDL-1.0
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| 37 | */
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| 38 |
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| 39 | #ifndef _kAVLGetBestFit_h_
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| 40 | #define _kAVLGetBestFit_h_
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| 41 |
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| 42 |
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| 43 | /**
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| 44 | * Finds the best fitting node in the tree for the given Key value.
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| 45 | * @returns Pointer to the best fitting node found.
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| 46 | * @param ppTree Pointer to Pointer to the tree root node.
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| 47 | * @param Key The Key of which is to be found a best fitting match for..
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| 48 | * @param fAbove TRUE: Returned node is have the closest key to Key from above.
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| 49 | * FALSE: Returned node is have the closest key to Key from below.
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| 50 | * @sketch The best fitting node is always located in the searchpath above you.
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| 51 | * >= (above): The node where you last turned left.
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| 52 | * <= (below): the node where you last turned right.
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| 53 | */
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| 54 | KAVL_DECL(PKAVLNODECORE) KAVL_FN(GetBestFit)(PPKAVLNODECORE ppTree, KAVLKEY Key, bool fAbove)
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| 55 | {
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| 56 | PKAVLNODECORE pNode = KAVL_GET_POINTER_NULL(ppTree);
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| 57 | if (pNode)
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| 58 | {
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| 59 | PKAVLNODECORE pNodeLast = NULL;
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| 60 | if (fAbove)
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| 61 | { /* pNode->Key >= Key */
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| 62 | while (KAVL_NE(pNode->Key, Key))
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| 63 | {
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| 64 | if (KAVL_G(pNode->Key, Key))
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| 65 | {
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| 66 | if (pNode->pLeft != KAVL_NULL)
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| 67 | {
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| 68 | pNodeLast = pNode;
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| 69 | pNode = KAVL_GET_POINTER(&pNode->pLeft);
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| 70 | }
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| 71 | else
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| 72 | return pNode;
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| 73 | }
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| 74 | else
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| 75 | {
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| 76 | if (pNode->pRight != KAVL_NULL)
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| 77 | pNode = KAVL_GET_POINTER(&pNode->pRight);
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| 78 | else
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| 79 | return pNodeLast;
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| 80 | }
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| 81 | }
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| 82 | }
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| 83 | else
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| 84 | { /* pNode->Key <= Key */
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| 85 | while (KAVL_NE(pNode->Key, Key))
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| 86 | {
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| 87 | if (KAVL_G(pNode->Key, Key))
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| 88 | {
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| 89 | if (pNode->pLeft != KAVL_NULL)
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| 90 | pNode = KAVL_GET_POINTER(&pNode->pLeft);
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| 91 | else
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| 92 | return pNodeLast;
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| 93 | }
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| 94 | else
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| 95 | {
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| 96 | if (pNode->pRight != KAVL_NULL)
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| 97 | {
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| 98 | pNodeLast = pNode;
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| 99 | pNode = KAVL_GET_POINTER(&pNode->pRight);
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| 100 | }
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| 101 | else
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| 102 | return pNode;
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| 103 | }
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| 104 | }
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| 105 | }
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| 106 | }
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| 107 |
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| 108 | /* perfect match or nothing. */
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| 109 | return pNode;
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| 110 | }
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| 111 |
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| 112 |
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| 113 | #endif
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