88 lines
2.2 KiB
C
88 lines
2.2 KiB
C
/*-
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* LstInsert.c --
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* Insert a new datum before an old one
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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: lstInsert.c,v 1.6 89/06/13 15:01:43 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_Insert --
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* Insert a new node with the given piece of data before the given
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* node in 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 firstPtr field will be changed if ln is the first node in the
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* list.
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*
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*-----------------------------------------------------------------------
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*/
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ReturnStatus
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Lst_Insert (l, ln, d)
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Lst l; /* list to manipulate */
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LstNode ln; /* node before which to insert d */
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ClientData d; /* datum to be inserted */
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{
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register ListNode nLNode; /* new lnode for d */
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register ListNode lNode = (ListNode)ln;
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register List list = (List)l;
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/*
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* check validity of arguments
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*/
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if (LstValid (l) && (LstIsEmpty (l) && ln == NILLNODE))
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goto ok;
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if (!LstValid (l) || LstIsEmpty (l) || !LstNodeValid (ln, l)) {
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return (FAILURE);
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}
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ok:
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PAlloc (nLNode, ListNode);
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nLNode->datum = d;
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nLNode->useCount = nLNode->flags = 0;
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if (ln == NILLNODE) {
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if (list->isCirc) {
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nLNode->prevPtr = nLNode->nextPtr = nLNode;
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} else {
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nLNode->prevPtr = nLNode->nextPtr = NilListNode;
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}
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list->firstPtr = list->lastPtr = nLNode;
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} else {
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nLNode->prevPtr = lNode->prevPtr;
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nLNode->nextPtr = lNode;
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if (nLNode->prevPtr != NilListNode) {
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nLNode->prevPtr->nextPtr = nLNode;
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}
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lNode->prevPtr = nLNode;
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if (lNode == list->firstPtr) {
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list->firstPtr = nLNode;
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}
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}
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return (SUCCESS);
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}
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