106 lines
2.8 KiB
C
106 lines
2.8 KiB
C
/*-
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* LstRemove.c --
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* Remove an element from a list
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*
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* Copyright (c) 1988 by University of California Regents
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*
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* Permission to use, copy, modify, and distribute this
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* software and its documentation for any purpose and without
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* fee is hereby granted, provided that the above copyright
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* notice appears in all copies. Neither the University of California nor
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* Adam de Boor makes any representations about the suitability of this
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* software for any purpose. It is provided "as is" without
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* express or implied warranty.
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*/
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#if !defined(lint) && defined(keep_rcsid)
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static char *rcsid =
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"Id: lstRemove.c,v 1.7 89/06/13 15:01:51 adam Exp $ SPRITE (Berkeley)";
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#endif lint
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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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