| 1 | /* $Id: avl_GetBestFit.cpp.h 4071 2007-08-07 17:07:59Z 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) 1999-2002 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 as published by the Free Software Foundation,
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| 15 | * in version 2 as it comes in the "COPYING" file of the VirtualBox OSE
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| 16 | * distribution. VirtualBox OSE is distributed in the hope that it will
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| 17 | * be useful, but WITHOUT ANY WARRANTY of any kind.
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| 18 | */
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| 19 |
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| 20 | #ifndef _kAVLGetBestFit_h_
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| 21 | #define _kAVLGetBestFit_h_
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| 22 |
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| 23 |
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| 24 | /**
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| 25 | * Finds the best fitting node in the tree for the given Key value.
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| 26 | * @returns Pointer to the best fitting node found.
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| 27 | * @param ppTree Pointer to Pointer to the tree root node.
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| 28 | * @param Key The Key of which is to be found a best fitting match for..
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| 29 | * @param fAbove TRUE: Returned node is have the closest key to Key from above.
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| 30 | * FALSE: Returned node is have the closest key to Key from below.
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| 31 | * @sketch The best fitting node is always located in the searchpath above you.
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| 32 | * >= (above): The node where you last turned left.
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| 33 | * <= (below): the node where you last turned right.
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| 34 | */
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| 35 | RTDECL(PKAVLNODECORE) KAVL_FN(GetBestFit)(PPKAVLNODECORE ppTree, KAVLKEY Key, bool fAbove)
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| 36 | {
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| 37 | register PKAVLNODECORE pNode = KAVL_GET_POINTER_NULL(ppTree);
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| 38 | if (pNode)
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| 39 | {
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| 40 | PKAVLNODECORE pNodeLast = NULL;
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| 41 | if (fAbove)
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| 42 | { /* pNode->Key >= Key */
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| 43 | while (KAVL_NE(pNode->Key, Key))
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| 44 | {
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| 45 | if (KAVL_G(pNode->Key, Key))
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| 46 | {
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| 47 | if (pNode->pLeft != KAVL_NULL)
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| 48 | {
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| 49 | pNodeLast = pNode;
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| 50 | pNode = KAVL_GET_POINTER(&pNode->pLeft);
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| 51 | }
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| 52 | else
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| 53 | return pNode;
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| 54 | }
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| 55 | else
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| 56 | {
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| 57 | if (pNode->pRight != KAVL_NULL)
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| 58 | pNode = KAVL_GET_POINTER(&pNode->pRight);
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| 59 | else
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| 60 | return pNodeLast;
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| 61 | }
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| 62 | }
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| 63 | }
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| 64 | else
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| 65 | { /* pNode->Key <= Key */
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| 66 | while (KAVL_NE(pNode->Key, Key))
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| 67 | {
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| 68 | if (KAVL_G(pNode->Key, Key))
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| 69 | {
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| 70 | if (pNode->pLeft != KAVL_NULL)
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| 71 | pNode = KAVL_GET_POINTER(&pNode->pLeft);
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| 72 | else
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| 73 | return pNodeLast;
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| 74 | }
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| 75 | else
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| 76 | {
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| 77 | if (pNode->pRight != KAVL_NULL)
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| 78 | {
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| 79 | pNodeLast = pNode;
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| 80 | pNode = KAVL_GET_POINTER(&pNode->pRight);
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| 81 | }
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| 82 | else
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| 83 | return pNode;
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| 84 | }
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| 85 | }
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| 86 | }
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| 87 | }
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| 88 |
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| 89 | /* perfect match or nothing. */
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| 90 | return pNode;
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| 91 | }
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| 92 |
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| 93 |
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| 94 | #endif
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