| 1 | /* $Id: avl_RemoveNode.cpp.h 65208 2017-01-09 14:39:54Z vboxsync $ */
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| 2 | /** @file
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| 3 | * kAVLRemove2 - Remove specific node (by pointer) from an AVL tree.
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| 4 | */
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| 5 |
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| 6 | /*
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| 7 | * Copyright (C) 2001-2012 knut st. osmundsen (bird-src-spam@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 | /**
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| 33 | * Removes the specified node from the tree.
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| 34 | *
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| 35 | * @returns Pointer to the removed node (NULL if not in the tree)
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| 36 | * @param ppTree Pointer to the AVL-tree root structure.
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| 37 | * @param pNode Pointer to the node to be removed.
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| 38 | *
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| 39 | * @remark This implementation isn't the most efficient, but it's relatively
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| 40 | * short and easier to manage.
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| 41 | */
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| 42 | KAVL_DECL(PKAVLNODECORE) KAVL_FN(RemoveNode)(PPKAVLNODECORE ppTree, PKAVLNODECORE pNode)
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| 43 | {
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| 44 | #ifdef KAVL_EQUAL_ALLOWED
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| 45 | /*
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| 46 | * Find the right node by key together with the parent node.
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| 47 | */
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| 48 | KAVLKEY const Key = pNode->Key;
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| 49 | PKAVLNODECORE pParent = NULL;
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| 50 | PKAVLNODECORE pCurNode = KAVL_GET_POINTER_NULL(ppTree);
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| 51 | if (!pCurNode)
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| 52 | return NULL;
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| 53 | while (KAVL_NE(pCurNode->Key, Key))
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| 54 | {
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| 55 | pParent = pCurNode;
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| 56 | if (KAVL_G(pCurNode->Key, Key))
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| 57 | {
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| 58 | if (pCurNode->pLeft != KAVL_NULL)
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| 59 | pCurNode = KAVL_GET_POINTER(&pCurNode->pLeft);
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| 60 | else
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| 61 | return NULL;
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| 62 | }
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| 63 | else
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| 64 | {
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| 65 | if (pCurNode->pRight != KAVL_NULL)
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| 66 | pCurNode = KAVL_GET_POINTER(&pCurNode->pRight);
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| 67 | else
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| 68 | return NULL;
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| 69 | }
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| 70 | }
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| 71 |
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| 72 | if (pCurNode != pNode)
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| 73 | {
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| 74 | /*
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| 75 | * It's not the one we want, but it could be in the duplicate list.
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| 76 | */
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| 77 | while (pCurNode->pList != KAVL_NULL)
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| 78 | {
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| 79 | PKAVLNODECORE pNext = KAVL_GET_POINTER(&pCurNode->pList);
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| 80 | if (pNext == pNode)
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| 81 | {
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| 82 | if (pNode->pList != KAVL_NULL)
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| 83 | KAVL_SET_POINTER(&pCurNode->pList, KAVL_GET_POINTER(&pNode->pList));
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| 84 | else
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| 85 | pCurNode->pList = KAVL_NULL;
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| 86 | pNode->pList = KAVL_NULL;
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| 87 | return pNode;
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| 88 | }
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| 89 | pCurNode = pNext;
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| 90 | }
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| 91 | return NULL;
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| 92 | }
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| 93 |
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| 94 | /*
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| 95 | * Ok, it's the one we want alright.
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| 96 | *
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| 97 | * Simply remove it if it's the only one with they Key, if there are
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| 98 | * duplicates we'll have to unlink it and insert the first duplicate
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| 99 | * in our place.
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| 100 | */
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| 101 | if (pNode->pList == KAVL_NULL)
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| 102 | KAVL_FN(Remove)(ppTree, pNode->Key);
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| 103 | else
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| 104 | {
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| 105 | PKAVLNODECORE pNewUs = KAVL_GET_POINTER(&pNode->pList);
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| 106 |
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| 107 | pNewUs->uchHeight = pNode->uchHeight;
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| 108 |
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| 109 | if (pNode->pLeft != KAVL_NULL)
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| 110 | KAVL_SET_POINTER(&pNewUs->pLeft, KAVL_GET_POINTER(&pNode->pLeft));
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| 111 | else
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| 112 | pNewUs->pLeft = KAVL_NULL;
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| 113 |
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| 114 | if (pNode->pRight != KAVL_NULL)
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| 115 | KAVL_SET_POINTER(&pNewUs->pRight, KAVL_GET_POINTER(&pNode->pRight));
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| 116 | else
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| 117 | pNewUs->pRight = KAVL_NULL;
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| 118 |
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| 119 | if (pParent)
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| 120 | {
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| 121 | if (KAVL_GET_POINTER_NULL(&pParent->pLeft) == pNode)
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| 122 | KAVL_SET_POINTER(&pParent->pLeft, pNewUs);
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| 123 | else
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| 124 | KAVL_SET_POINTER(&pParent->pRight, pNewUs);
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| 125 | }
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| 126 | else
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| 127 | KAVL_SET_POINTER(ppTree, pNewUs);
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| 128 | }
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| 129 |
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| 130 | return pNode;
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| 131 |
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| 132 | #else
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| 133 | /*
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| 134 | * Delete it, if we got the wrong one, reinsert it.
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| 135 | *
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| 136 | * This ASSUMS that the caller is NOT going to hand us a lot
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| 137 | * of wrong nodes but just uses this API for his convenience.
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| 138 | */
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| 139 | KAVLNODE *pRemovedNode = KAVL_FN(Remove)(pRoot, pNode->Key);
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| 140 | if (pRemovedNode == pNode)
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| 141 | return pRemovedNode;
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| 142 |
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| 143 | KAVL_FN(Insert)(pRoot, pRemovedNode);
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| 144 | return NULL;
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| 145 | #endif
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| 146 | }
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| 147 |
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