| 1 | /* $Id: kAvlRemove2.h 7 2008-02-04 02:08:02Z bird $ */
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| 2 | /** @file
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| 3 | * kAvlTmpl - Templated AVL Trees, Remove A Specific 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 | * Removes the specified node from the tree.
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| 37 | *
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| 38 | * @returns Pointer to the removed node (NULL if not in the tree)
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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 | *
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| 42 | * @remark This implementation isn't the most efficient, but this short and
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| 43 | * easier to manage.
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| 44 | */
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| 45 | KAVL_DECL(KAVLNODE *) KAVL_FN(Remove2)(KAVLTROOT *pRoot, KAVLNODE *pNode)
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| 46 | {
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| 47 | #ifdef KAVL_EQUAL_ALLOWED
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| 48 | /*
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| 49 | * Find the right node by key and see if it's what we want.
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| 50 | */
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| 51 | KAVLNODE *pParent;
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| 52 | KAVLNODE *pCurNode = KAVL_FN(GetWithParent)(pRoot, pNode->mKey, &pParent);
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| 53 | if (!pCurNode)
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| 54 | return NULL;
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| 55 | KAVL_WRITE_LOCK(pRoot); /** @todo the locking here isn't 100% sane. The only way to archive that is by no calling worker functions. */
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| 56 | if (pCurNode != pNode)
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| 57 | {
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| 58 | /*
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| 59 | * It's not the one we want, but it could be in the duplicate list.
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| 60 | */
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| 61 | while (pCurNode->mpList != KAVL_NULL)
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| 62 | {
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| 63 | KAVLNODE *pNext = KAVL_GET_POINTER(&pCurNode->mpList);
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| 64 | if (pNext == pNode)
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| 65 | {
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| 66 | KAVL_SET_POINTER_NULL(&pCurNode->mpList, KAVL_GET_POINTER_NULL(&pNode->mpList));
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| 67 | pNode->mpList = KAVL_NULL;
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| 68 | KAVL_LOOKTHRU_INVALIDATE_NODE(pRoot, pNode, pNode->mKey);
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| 69 | KAVL_WRITE_UNLOCK(pRoot);
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| 70 | return pNode;
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| 71 | }
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| 72 | pCurNode = pNext;
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| 73 | }
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| 74 | KAVL_WRITE_UNLOCK(pRoot);
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| 75 | return NULL;
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| 76 | }
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| 77 |
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| 78 | /*
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| 79 | * Ok, it's the one we want alright.
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| 80 | *
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| 81 | * Simply remove it if it's the only one with they Key,
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| 82 | * if there are duplicates we'll have to unlink it and
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| 83 | * insert the first duplicate in our place.
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| 84 | */
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| 85 | if (pNode->mpList == KAVL_NODE)
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| 86 | {
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| 87 | KAVL_WRITE_UNLOCK(pRoot);
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| 88 | KAVL_FN(Remove)(pRoot, pNode->mKey);
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| 89 | }
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| 90 | else
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| 91 | {
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| 92 | KAVLNODE *pNewUs = KAVL_GET_POINTER(&pNode->mpList);
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| 93 |
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| 94 | pNewUs->mHeight = pNode->mHeight;
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| 95 |
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| 96 | if (pNode->mpLeft != KAVL_NULL)
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| 97 | KAVL_SET_POINTER(&pNewUs->mpLeft, KAVL_GET_POINTER(&pNode->mpLeft))
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| 98 | else
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| 99 | pNewUs->mpLeft = KAVL_NULL;
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| 100 |
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| 101 | if (pNode->mpRight != KAVL_NULL)
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| 102 | KAVL_SET_POINTER(&pNewUs->mpRight, KAVL_GET_POINTER(&pNode->mpRight))
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| 103 | else
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| 104 | pNewUs->mpRight = KAVL_NULL;
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| 105 |
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| 106 | if (pParent)
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| 107 | {
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| 108 | if (KAVL_GET_POINTER_NULL(&pParent->mpLeft) == pNode)
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| 109 | KAVL_SET_POINTER(&pParent->mpLeft, pNewUs);
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| 110 | else
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| 111 | KAVL_SET_POINTER(&pParent->mpRight, pNewUs);
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| 112 | }
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| 113 | else
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| 114 | KAVL_SET_POINTER(&pRoot->mpRoot, pNewUs);
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| 115 |
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| 116 | KAVL_LOOKTHRU_INVALIDATE_NODE(pRoot, pNode, pNode->mKey);
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| 117 | KAVL_WRITE_UNLOCK(pRoot);
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| 118 | }
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| 119 |
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| 120 | return pNode;
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| 121 |
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| 122 | #else
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| 123 | /*
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| 124 | * Delete it, if we got the wrong one, reinsert it.
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| 125 | *
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| 126 | * This ASSUMS that the caller is NOT going to hand us a lot
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| 127 | * of wrong nodes but just uses this API for his convenience.
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| 128 | */
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| 129 | KAVLNODE *pRemovedNode = KAVL_FN(Remove)(pRoot, pNode->mKey);
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| 130 | if (pRemovedNode == pNode)
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| 131 | return pRemovedNode;
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| 132 |
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| 133 | KAVL_FN(Insert)(pRoot, pRemovedNode);
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| 134 | return NULL;
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| 135 | #endif
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| 136 | }
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| 137 |
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