1 /* 2 * Copyright (c) 1988, 1989, 1990, 1993 3 * The Regents of the University of California. All rights reserved. 4 * 5 * This code is derived from software contributed to Berkeley by 6 * Adam de Boor. 7 * 8 * %sccs.include.redist.c% 9 */ 10 11 #ifndef lint 12 static char sccsid[] = "@(#)lstDeQueue.c 8.2 (Berkeley) 04/28/95"; 13 #endif /* not lint */ 14 15 /*- 16 * LstDeQueue.c -- 17 * Remove the node and return its datum from the head of the list 18 */ 19 20 #include "lstInt.h" 21 22 /*- 23 *----------------------------------------------------------------------- 24 * Lst_DeQueue -- 25 * Remove and return the datum at the head of the given list. 26 * 27 * Results: 28 * The datum in the node at the head or (ick) NIL if the list 29 * is empty. 30 * 31 * Side Effects: 32 * The head node is removed from the list. 33 * 34 *----------------------------------------------------------------------- 35 */ 36 ClientData 37 Lst_DeQueue (l) 38 Lst l; 39 { 40 ClientData rd; 41 register ListNode tln; 42 43 tln = (ListNode) Lst_First (l); 44 if (tln == NilListNode) { 45 return ((ClientData) NIL); 46 } 47 48 rd = tln->datum; 49 if (Lst_Remove (l, (LstNode)tln) == FAILURE) { 50 return ((ClientData) NIL); 51 } else { 52 return (rd); 53 } 54 } 55 56