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40 static char sccsid[] = "@(#)lstRemove.c 8.1 (Berkeley) 6/6/93";
45 * Remove an element from a list
51 *-----------------------------------------------------------------------
53 * Remove the given node from the given list.
59 * The list's firstPtr will be set to NilListNode if ln is the last
60 * node on the list. firsPtr and lastPtr will be altered if ln is
61 * either the first or last node, respectively, on the list.
63 *-----------------------------------------------------------------------
70 register List list = (List) l;
71 register ListNode lNode = (ListNode) ln;
74 !LstNodeValid (ln, l)) {
79 * unlink it from the list
81 if (lNode->nextPtr != NilListNode) {
82 lNode->nextPtr->prevPtr = lNode->prevPtr;
84 if (lNode->prevPtr != NilListNode) {
85 lNode->prevPtr->nextPtr = lNode->nextPtr;
89 * if either the firstPtr or lastPtr of the list point to this node,
90 * adjust them accordingly
92 if (list->firstPtr == lNode) {
93 list->firstPtr = lNode->nextPtr;
95 if (list->lastPtr == lNode) {
96 list->lastPtr = lNode->prevPtr;
100 * Sequential access stuff. If the node we're removing is the current
101 * node in the list, reset the current node to the previous one. If the
102 * previous one was non-existent (prevPtr == NilListNode), we set the
103 * end to be Unknown, since it is.
105 if (list->isOpen && (list->curPtr == lNode)) {
106 list->curPtr = list->prevPtr;
107 if (list->curPtr == NilListNode) {
108 list->atEnd = Unknown;
113 * the only way firstPtr can still point to ln is if ln is the last
114 * node on the list (the list is circular, so lNode->nextptr == lNode in
115 * this case). The list is, therefore, empty and is marked as such
117 if (list->firstPtr == lNode) {
118 list->firstPtr = NilListNode;
122 * note that the datum is unmolested. The caller must free it as
123 * necessary and as expected.
125 if (lNode->useCount == 0) {
128 lNode->flags |= LN_DELETED;