| 1 | /* $Id: kAvlRemove2.h 34 2009-11-08 19:38:40Z 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) 1999-2009 Knut St. Osmundsen <bird-kStuff-spamix@anduin.net>
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| 8 | *
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| 9 | * Permission is hereby granted, free of charge, to any person
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| 10 | * obtaining a copy of this software and associated documentation
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| 11 | * files (the "Software"), to deal in the Software without
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| 12 | * restriction, including without limitation the rights to use,
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| 13 | * copy, modify, merge, publish, distribute, sublicense, and/or sell
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| 14 | * copies of the Software, and to permit persons to whom the
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| 15 | * Software is furnished to do so, subject to the following
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| 16 | * conditions:
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| 17 | *
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| 18 | * The above copyright notice and this permission notice shall be
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| 19 | * included in all copies or substantial portions of the Software.
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| 20 | *
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| 21 | * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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| 22 | * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
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| 23 | * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
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| 24 | * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
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| 25 | * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
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| 26 | * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
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| 27 | * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
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| 28 | * OTHER DEALINGS IN THE SOFTWARE.
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| 29 | */
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| 30 |
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| 31 | /**
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| 32 | * Removes the specified node from the tree.
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| 33 | *
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| 34 | * @returns Pointer to the removed node (NULL if not in the tree)
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| 35 | * @param pRoot Pointer to the AVL-tree root structure.
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| 36 | * @param Key The Key of which is to be found a best fitting match for..
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| 37 | *
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| 38 | * @remark This implementation isn't the most efficient, but this short and
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| 39 | * easier to manage.
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| 40 | */
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| 41 | KAVL_DECL(KAVLNODE *) KAVL_FN(Remove2)(KAVLROOT *pRoot, KAVLNODE *pNode)
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| 42 | {
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| 43 | #ifdef KAVL_EQUAL_ALLOWED
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| 44 | /*
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| 45 | * Find the right node by key and see if it's what we want.
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| 46 | */
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| 47 | KAVLNODE *pParent;
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| 48 | KAVLNODE *pCurNode = KAVL_FN(GetWithParent)(pRoot, pNode->mKey, &pParent);
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| 49 | if (!pCurNode)
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| 50 | return NULL;
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| 51 | 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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| 52 | if (pCurNode != pNode)
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| 53 | {
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| 54 | /*
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| 55 | * It's not the one we want, but it could be in the duplicate list.
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| 56 | */
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| 57 | while (pCurNode->mpList != KAVL_NULL)
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| 58 | {
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| 59 | KAVLNODE *pNext = KAVL_GET_POINTER(&pCurNode->mpList);
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| 60 | if (pNext == pNode)
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| 61 | {
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| 62 | KAVL_SET_POINTER_NULL(&pCurNode->mpList, KAVL_GET_POINTER_NULL(&pNode->mpList));
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| 63 | pNode->mpList = KAVL_NULL;
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| 64 | KAVL_LOOKTHRU_INVALIDATE_NODE(pRoot, pNode, pNode->mKey);
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| 65 | KAVL_WRITE_UNLOCK(pRoot);
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| 66 | return pNode;
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| 67 | }
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| 68 | pCurNode = pNext;
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| 69 | }
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| 70 | KAVL_WRITE_UNLOCK(pRoot);
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| 71 | return NULL;
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| 72 | }
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| 73 |
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| 74 | /*
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| 75 | * Ok, it's the one we want alright.
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| 76 | *
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| 77 | * Simply remove it if it's the only one with they Key,
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| 78 | * if there are duplicates we'll have to unlink it and
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| 79 | * insert the first duplicate in our place.
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| 80 | */
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| 81 | if (pNode->mpList == KAVL_NULL)
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| 82 | {
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| 83 | KAVL_WRITE_UNLOCK(pRoot);
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| 84 | KAVL_FN(Remove)(pRoot, pNode->mKey);
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| 85 | }
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| 86 | else
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| 87 | {
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| 88 | KAVLNODE *pNewUs = KAVL_GET_POINTER(&pNode->mpList);
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| 89 |
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| 90 | pNewUs->mHeight = pNode->mHeight;
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| 91 |
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| 92 | if (pNode->mpLeft != KAVL_NULL)
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| 93 | KAVL_SET_POINTER(&pNewUs->mpLeft, KAVL_GET_POINTER(&pNode->mpLeft))
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| 94 | else
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| 95 | pNewUs->mpLeft = KAVL_NULL;
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| 96 |
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| 97 | if (pNode->mpRight != KAVL_NULL)
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| 98 | KAVL_SET_POINTER(&pNewUs->mpRight, KAVL_GET_POINTER(&pNode->mpRight))
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| 99 | else
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| 100 | pNewUs->mpRight = KAVL_NULL;
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| 101 |
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| 102 | if (pParent)
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| 103 | {
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| 104 | if (KAVL_GET_POINTER_NULL(&pParent->mpLeft) == pNode)
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| 105 | KAVL_SET_POINTER(&pParent->mpLeft, pNewUs);
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| 106 | else
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| 107 | KAVL_SET_POINTER(&pParent->mpRight, pNewUs);
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| 108 | }
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| 109 | else
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| 110 | KAVL_SET_POINTER(&pRoot->mpRoot, pNewUs);
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| 111 |
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| 112 | KAVL_LOOKTHRU_INVALIDATE_NODE(pRoot, pNode, pNode->mKey);
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| 113 | KAVL_WRITE_UNLOCK(pRoot);
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| 114 | }
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| 115 |
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| 116 | return pNode;
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| 117 |
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| 118 | #else
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| 119 | /*
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| 120 | * Delete it, if we got the wrong one, reinsert it.
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| 121 | *
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| 122 | * This ASSUMS that the caller is NOT going to hand us a lot
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| 123 | * of wrong nodes but just uses this API for his convenience.
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| 124 | */
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| 125 | KAVLNODE *pRemovedNode = KAVL_FN(Remove)(pRoot, pNode->mKey);
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| 126 | if (pRemovedNode == pNode)
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| 127 | return pRemovedNode;
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| 128 |
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| 129 | KAVL_FN(Insert)(pRoot, pRemovedNode);
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| 130 | return NULL;
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| 131 | #endif
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| 132 | }
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| 133 |
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