132 lines
4.2 KiB
C
132 lines
4.2 KiB
C
/*
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* Copyright (c) 1988, 1989, 1990, 1993
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* The Regents of the University of California. All rights reserved.
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*
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* This code is derived from software contributed to Berkeley by
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* Adam de Boor.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by the University of
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* California, Berkeley and its contributors.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#ifndef lint
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static char sccsid[] = "@(#)lstRemove.c 8.1 (Berkeley) 6/6/93";
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#endif /* not lint */
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/*-
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* LstRemove.c --
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* Remove an element from a list
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*/
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#include "lstInt.h"
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/*-
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*-----------------------------------------------------------------------
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* Lst_Remove --
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* Remove the given node from the given list.
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*
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* Results:
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* SUCCESS or FAILURE.
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*
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* Side Effects:
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* The list's firstPtr will be set to NilListNode if ln is the last
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* node on the list. firsPtr and lastPtr will be altered if ln is
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* either the first or last node, respectively, on the list.
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*
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*-----------------------------------------------------------------------
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*/
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ReturnStatus
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Lst_Remove (l, ln)
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Lst l;
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LstNode ln;
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{
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register List list = (List) l;
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register ListNode lNode = (ListNode) ln;
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if (!LstValid (l) ||
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!LstNodeValid (ln, l)) {
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return (FAILURE);
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}
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/*
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* unlink it from the list
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*/
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if (lNode->nextPtr != NilListNode) {
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lNode->nextPtr->prevPtr = lNode->prevPtr;
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}
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if (lNode->prevPtr != NilListNode) {
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lNode->prevPtr->nextPtr = lNode->nextPtr;
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}
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/*
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* if either the firstPtr or lastPtr of the list point to this node,
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* adjust them accordingly
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*/
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if (list->firstPtr == lNode) {
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list->firstPtr = lNode->nextPtr;
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}
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if (list->lastPtr == lNode) {
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list->lastPtr = lNode->prevPtr;
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}
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/*
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* Sequential access stuff. If the node we're removing is the current
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* node in the list, reset the current node to the previous one. If the
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* previous one was non-existent (prevPtr == NilListNode), we set the
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* end to be Unknown, since it is.
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*/
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if (list->isOpen && (list->curPtr == lNode)) {
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list->curPtr = list->prevPtr;
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if (list->curPtr == NilListNode) {
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list->atEnd = Unknown;
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}
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}
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/*
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* the only way firstPtr can still point to ln is if ln is the last
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* node on the list (the list is circular, so lNode->nextptr == lNode in
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* this case). The list is, therefore, empty and is marked as such
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*/
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if (list->firstPtr == lNode) {
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list->firstPtr = NilListNode;
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}
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/*
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* note that the datum is unmolested. The caller must free it as
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* necessary and as expected.
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*/
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if (lNode->useCount == 0) {
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free ((Address)ln);
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} else {
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lNode->flags |= LN_DELETED;
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}
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return (SUCCESS);
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}
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