| 1 | /* $Id: kAvlGetBestFit.h 7 2008-02-04 02:08:02Z bird $ */
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| 2 | /** @file
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| 3 | * kAvlTmpl - Templated AVL Trees, Get Best Fitting Node.
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| 4 | */
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| 5 |
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| 6 | /*
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| 7 | * Copyright (c) 1999-2007 knut st. osmundsen <bird-src-spam@anduin.net>
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| 8 | *
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| 9 | * This file is part of kStuff.
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| 10 | *
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| 11 | * kStuff is free software; you can redistribute it and/or
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| 12 | * modify it under the terms of the GNU Lesser General Public
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| 13 | * License as published by the Free Software Foundation; either
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| 14 | * version 2.1 of the License, or (at your option) any later version.
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| 15 | *
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| 16 | * kStuff is distributed in the hope that it will be useful,
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| 17 | * but WITHOUT ANY WARRANTY; without even the implied warranty of
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| 18 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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| 19 | * Lesser General Public License for more details.
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| 20 | *
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| 21 | * You should have received a copy of the GNU Lesser General Public
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| 22 | * License along with kStuff; if not, write to the Free Software
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| 23 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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| 24 | *
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| 25 | *
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| 26 | * As a special exception, since this is a source file and not a header
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| 27 | * file, you are granted permission to #include this file as you wish
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| 28 | * without this in itself causing the resulting program or whatever to be
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| 29 | * covered by the LGPL license. This exception does not however invalidate
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| 30 | * any other reasons why the resulting program/whatever should not be
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| 31 | * covered the LGPL or GPL.
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| 32 | */
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| 33 |
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| 34 |
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| 35 | /**
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| 36 | * Finds the best fitting node in the tree for the given Key value.
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| 37 | *
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| 38 | * @returns Pointer to the best fitting node found.
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| 39 | * @param pRoot Pointer to the AVL-tree root structure.
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| 40 | * @param Key The Key of which is to be found a best fitting match for..
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| 41 | * @param fAbove K_TRUE: Returned node is have the closest key to Key from above.
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| 42 | * K_FALSE: Returned node is have the closest key to Key from below.
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| 43 | * @sketch The best fitting node is always located in the searchpath above you.
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| 44 | * >= (above): The node where you last turned left.
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| 45 | * <= (below): the node where you last turned right.
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| 46 | */
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| 47 | KAVL_DECL(KAVLNODE *) KAVL_FN(GetBestFit)(KAVLROOT *pRoot, KAVLKEY Key, KBOOL fAbove)
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| 48 | {
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| 49 | register KAVLNODE *pNode;
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| 50 | KAVLNODE *pNodeLast;
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| 51 |
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| 52 | KAVL_READ_LOCK(pLook);
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| 53 | if (pRoot->mpRoot == KAVL_NULL)
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| 54 | {
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| 55 | KAVL_READ_UNLOCK(pLook);
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| 56 | return NULL;
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| 57 | }
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| 58 |
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| 59 | pNode = KAVL_GET_POINTER(&pRoot->mpRoot);
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| 60 | pNodeLast = NULL;
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| 61 | if (fAbove)
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| 62 | { /* pNode->mKey >= Key */
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| 63 | while (KAVL_NE(pNode->mKey, Key))
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| 64 | {
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| 65 | if (KAVL_G(pNode->mKey, Key))
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| 66 | {
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| 67 | if (pNode->mpLeft == KAVL_NULL)
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| 68 | {
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| 69 | KAVL_READ_UNLOCK(pLook);
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| 70 | return pNode;
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| 71 | }
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| 72 | pNodeLast = pNode;
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| 73 | pNode = KAVL_GET_POINTER(&pNode->mpLeft);
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| 74 | }
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| 75 | else
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| 76 | {
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| 77 | if (pNode->mpRight == KAVL_NULL)
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| 78 | {
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| 79 | KAVL_READ_UNLOCK(pLook);
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| 80 | return pNodeLast;
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| 81 | }
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| 82 | pNode = KAVL_GET_POINTER(&pNode->mpRight);
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| 83 | }
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| 84 | }
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| 85 | }
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| 86 | else
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| 87 | { /* pNode->mKey <= Key */
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| 88 | while (KAVL_NE(pNode->mKey, Key))
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| 89 | {
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| 90 | if (KAVL_G(pNode->mKey, Key))
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| 91 | {
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| 92 | if (pNode->mpLeft == KAVL_NULL)
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| 93 | {
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| 94 | KAVL_READ_UNLOCK(pLook);
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| 95 | return pNodeLast;
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| 96 | }
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| 97 | pNode = KAVL_GET_POINTER(&pNode->mpLeft);
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| 98 | }
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| 99 | else
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| 100 | {
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| 101 | if (pNode->mpRight == KAVL_NULL)
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| 102 | {
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| 103 | KAVL_READ_UNLOCK(pLook);
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| 104 | return pNode;
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| 105 | }
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| 106 | pNodeLast = pNode;
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| 107 | pNode = KAVL_GET_POINTER(&pNode->mpRight);
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| 108 | }
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| 109 | }
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| 110 | }
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| 111 |
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| 112 | /* perfect match or nothing. */
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| 113 | KAVL_READ_UNLOCK(pLook);
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| 114 | return pNode;
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| 115 | }
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| 116 |
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