| 1 | /* |
| 2 | * Copyright (c) 1988, 1989, 1990 The Regents of the University of California. |
| 3 | * All rights reserved. |
| 4 | * |
| 5 | * This code is derived from software contributed to Berkeley by |
| 6 | * Adam de Boor. |
| 7 | * |
| 8 | * Redistribution and use in source and binary forms, with or without |
| 9 | * modification, are permitted provided that the following conditions |
| 10 | * are met: |
| 11 | * 1. Redistributions of source code must retain the above copyright |
| 12 | * notice, this list of conditions and the following disclaimer. |
| 13 | * 2. Redistributions in binary form must reproduce the above copyright |
| 14 | * notice, this list of conditions and the following disclaimer in the |
| 15 | * documentation and/or other materials provided with the distribution. |
| 16 | * 3. All advertising materials mentioning features or use of this software |
| 17 | * must display the following acknowledgement: |
| 18 | * This product includes software developed by the University of |
| 19 | * California, Berkeley and its contributors. |
| 20 | * 4. Neither the name of the University nor the names of its contributors |
| 21 | * may be used to endorse or promote products derived from this software |
| 22 | * without specific prior written permission. |
| 23 | * |
| 24 | * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND |
| 25 | * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
| 26 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
| 27 | * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE |
| 28 | * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL |
| 29 | * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS |
| 30 | * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) |
| 31 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT |
| 32 | * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY |
| 33 | * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF |
| 34 | * SUCH DAMAGE. |
| 35 | */ |
| 36 | |
| 37 | #ifndef lint |
| 38 | static char sccsid[] = "@(#)lstRemove.c 5.3 (Berkeley) 6/1/90"; |
| 39 | #endif /* not lint */ |
| 40 | |
| 41 | /*- |
| 42 | * LstRemove.c -- |
| 43 | * Remove an element from a list |
| 44 | */ |
| 45 | |
| 46 | #include "lstInt.h" |
| 47 | |
| 48 | /*- |
| 49 | *----------------------------------------------------------------------- |
| 50 | * Lst_Remove -- |
| 51 | * Remove the given node from the given list. |
| 52 | * |
| 53 | * Results: |
| 54 | * SUCCESS or FAILURE. |
| 55 | * |
| 56 | * Side Effects: |
| 57 | * The list's firstPtr will be set to NilListNode if ln is the last |
| 58 | * node on the list. firsPtr and lastPtr will be altered if ln is |
| 59 | * either the first or last node, respectively, on the list. |
| 60 | * |
| 61 | *----------------------------------------------------------------------- |
| 62 | */ |
| 63 | ReturnStatus |
| 64 | Lst_Remove (l, ln) |
| 65 | Lst l; |
| 66 | LstNode ln; |
| 67 | { |
| 68 | register List list = (List) l; |
| 69 | register ListNode lNode = (ListNode) ln; |
| 70 | |
| 71 | if (!LstValid (l) || |
| 72 | !LstNodeValid (ln, l)) { |
| 73 | return (FAILURE); |
| 74 | } |
| 75 | |
| 76 | /* |
| 77 | * unlink it from the list |
| 78 | */ |
| 79 | if (lNode->nextPtr != NilListNode) { |
| 80 | lNode->nextPtr->prevPtr = lNode->prevPtr; |
| 81 | } |
| 82 | if (lNode->prevPtr != NilListNode) { |
| 83 | lNode->prevPtr->nextPtr = lNode->nextPtr; |
| 84 | } |
| 85 | |
| 86 | /* |
| 87 | * if either the firstPtr or lastPtr of the list point to this node, |
| 88 | * adjust them accordingly |
| 89 | */ |
| 90 | if (list->firstPtr == lNode) { |
| 91 | list->firstPtr = lNode->nextPtr; |
| 92 | } |
| 93 | if (list->lastPtr == lNode) { |
| 94 | list->lastPtr = lNode->prevPtr; |
| 95 | } |
| 96 | |
| 97 | /* |
| 98 | * Sequential access stuff. If the node we're removing is the current |
| 99 | * node in the list, reset the current node to the previous one. If the |
| 100 | * previous one was non-existent (prevPtr == NilListNode), we set the |
| 101 | * end to be Unknown, since it is. |
| 102 | */ |
| 103 | if (list->isOpen && (list->curPtr == lNode)) { |
| 104 | list->curPtr = list->prevPtr; |
| 105 | if (list->curPtr == NilListNode) { |
| 106 | list->atEnd = Unknown; |
| 107 | } |
| 108 | } |
| 109 | |
| 110 | /* |
| 111 | * the only way firstPtr can still point to ln is if ln is the last |
| 112 | * node on the list (the list is circular, so lNode->nextptr == lNode in |
| 113 | * this case). The list is, therefore, empty and is marked as such |
| 114 | */ |
| 115 | if (list->firstPtr == lNode) { |
| 116 | list->firstPtr = NilListNode; |
| 117 | } |
| 118 | |
| 119 | /* |
| 120 | * note that the datum is unmolested. The caller must free it as |
| 121 | * necessary and as expected. |
| 122 | */ |
| 123 | if (lNode->useCount == 0) { |
| 124 | free ((Address)ln); |
| 125 | } else { |
| 126 | lNode->flags |= LN_DELETED; |
| 127 | } |
| 128 | |
| 129 | return (SUCCESS); |
| 130 | } |
| 131 | |