| 1 | /* $Id: avl_GetBestFit.cpp.h 44528 2013-02-04 14:27:54Z 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) 1999-2012 knut st. osmundsen (bird-src-spam@anduin.net)
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| 10 | *
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| 11 | * This file is part of VirtualBox Open Source Edition (OSE), as
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| 12 | * available from http://www.virtualbox.org. This file is free software;
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| 13 | * you can redistribute it and/or modify it under the terms of the GNU
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| 14 | * General Public License (GPL) as published by the Free Software
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| 15 | * Foundation, in version 2 as it comes in the "COPYING" file of the
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| 16 | * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
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| 17 | * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
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| 18 | *
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| 19 | * The contents of this file may alternatively be used under the terms
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| 20 | * of the Common Development and Distribution License Version 1.0
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| 21 | * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
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| 22 | * VirtualBox OSE distribution, in which case the provisions of the
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| 23 | * CDDL are applicable instead of those of the GPL.
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| 24 | *
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| 25 | * You may elect to license modified versions of this file under the
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| 26 | * terms and conditions of either the GPL or the CDDL or both.
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| 27 | */
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| 28 |
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| 29 | #ifndef _kAVLGetBestFit_h_
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| 30 | #define _kAVLGetBestFit_h_
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| 31 |
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| 32 |
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| 33 | /**
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| 34 | * Finds the best fitting node in the tree for the given Key value.
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| 35 | * @returns Pointer to the best fitting node found.
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| 36 | * @param ppTree Pointer to Pointer to the tree root node.
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| 37 | * @param Key The Key of which is to be found a best fitting match for..
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| 38 | * @param fAbove TRUE: Returned node is have the closest key to Key from above.
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| 39 | * FALSE: Returned node is have the closest key to Key from below.
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| 40 | * @sketch The best fitting node is always located in the searchpath above you.
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| 41 | * >= (above): The node where you last turned left.
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| 42 | * <= (below): the node where you last turned right.
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| 43 | */
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| 44 | KAVL_DECL(PKAVLNODECORE) KAVL_FN(GetBestFit)(PPKAVLNODECORE ppTree, KAVLKEY Key, bool fAbove)
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| 45 | {
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| 46 | register PKAVLNODECORE pNode = KAVL_GET_POINTER_NULL(ppTree);
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| 47 | if (pNode)
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| 48 | {
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| 49 | PKAVLNODECORE pNodeLast = NULL;
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| 50 | if (fAbove)
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| 51 | { /* pNode->Key >= Key */
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| 52 | while (KAVL_NE(pNode->Key, Key))
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| 53 | {
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| 54 | if (KAVL_G(pNode->Key, Key))
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| 55 | {
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| 56 | if (pNode->pLeft != KAVL_NULL)
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| 57 | {
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| 58 | pNodeLast = pNode;
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| 59 | pNode = KAVL_GET_POINTER(&pNode->pLeft);
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| 60 | }
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| 61 | else
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| 62 | return pNode;
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| 63 | }
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| 64 | else
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| 65 | {
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| 66 | if (pNode->pRight != KAVL_NULL)
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| 67 | pNode = KAVL_GET_POINTER(&pNode->pRight);
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| 68 | else
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| 69 | return pNodeLast;
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| 70 | }
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| 71 | }
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| 72 | }
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| 73 | else
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| 74 | { /* pNode->Key <= Key */
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| 75 | while (KAVL_NE(pNode->Key, Key))
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| 76 | {
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| 77 | if (KAVL_G(pNode->Key, Key))
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| 78 | {
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| 79 | if (pNode->pLeft != KAVL_NULL)
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| 80 | pNode = KAVL_GET_POINTER(&pNode->pLeft);
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| 81 | else
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| 82 | return pNodeLast;
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| 83 | }
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| 84 | else
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| 85 | {
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| 86 | if (pNode->pRight != KAVL_NULL)
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| 87 | {
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| 88 | pNodeLast = pNode;
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| 89 | pNode = KAVL_GET_POINTER(&pNode->pRight);
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| 90 | }
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| 91 | else
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| 92 | return pNode;
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| 93 | }
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| 94 | }
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| 95 | }
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| 96 | }
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| 97 |
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| 98 | /* perfect match or nothing. */
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| 99 | return pNode;
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| 100 | }
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| 101 |
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| 102 |
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| 103 | #endif
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