1 /* 2 * Copyright (c) 1988, 1989, 1990 The Regents of the University of California. 3 * All rights reserved. 4 * 5 * This code is derived from software contributed to Berkeley by 6 * Adam de Boor. 7 * 8 * Redistribution and use in source and binary forms are permitted 9 * provided that the above copyright notice and this paragraph are 10 * duplicated in all such forms and that any documentation, 11 * advertising materials, and other materials related to such 12 * distribution and use acknowledge that the software was developed 13 * by the University of California, Berkeley. The name of the 14 * University may not be used to endorse or promote products derived 15 * from this software without specific prior written permission. 16 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR 17 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED 18 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. 19 */ 20 21 #ifndef lint 22 static char sccsid[] = "@(#)lstDeQueue.c 5.2 (Berkeley) 03/11/90"; 23 #endif /* not lint */ 24 25 /*- 26 * LstDeQueue.c -- 27 * Remove the node and return its datum from the head of the list 28 */ 29 30 #include "lstInt.h" 31 32 /*- 33 *----------------------------------------------------------------------- 34 * Lst_DeQueue -- 35 * Remove and return the datum at the head of the given list. 36 * 37 * Results: 38 * The datum in the node at the head or (ick) NIL if the list 39 * is empty. 40 * 41 * Side Effects: 42 * The head node is removed from the list. 43 * 44 *----------------------------------------------------------------------- 45 */ 46 ClientData 47 Lst_DeQueue (l) 48 Lst l; 49 { 50 ClientData rd; 51 register ListNode tln; 52 53 tln = (ListNode) Lst_First (l); 54 if (tln == NilListNode) { 55 return ((ClientData) NIL); 56 } 57 58 rd = tln->datum; 59 if (Lst_Remove (l, (LstNode)tln) == FAILURE) { 60 return ((ClientData) NIL); 61 } else { 62 return (rd); 63 } 64 } 65 66