1*40412Sbostic /*
2*40412Sbostic  * Copyright (c) 1988, 1989, 1990 The Regents of the University of California.
3*40412Sbostic  * All rights reserved.
440411Sbostic  *
5*40412Sbostic  * This code is derived from software contributed to Berkeley by
6*40412Sbostic  * Adam de Boor.
740411Sbostic  *
8*40412Sbostic  * Redistribution and use in source and binary forms are permitted
9*40412Sbostic  * provided that the above copyright notice and this paragraph are
10*40412Sbostic  * duplicated in all such forms and that any documentation,
11*40412Sbostic  * advertising materials, and other materials related to such
12*40412Sbostic  * distribution and use acknowledge that the software was developed
13*40412Sbostic  * by the University of California, Berkeley.  The name of the
14*40412Sbostic  * University may not be used to endorse or promote products derived
15*40412Sbostic  * from this software without specific prior written permission.
16*40412Sbostic  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
17*40412Sbostic  * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
18*40412Sbostic  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
1940411Sbostic  */
20*40412Sbostic 
2140411Sbostic #ifndef lint
22*40412Sbostic static char sccsid[] = "@(#)lstDeQueue.c	5.2 (Berkeley) 03/11/90";
23*40412Sbostic #endif /* not lint */
2440411Sbostic 
25*40412Sbostic /*-
26*40412Sbostic  * LstDeQueue.c --
27*40412Sbostic  *	Remove the node and return its datum from the head of the list
28*40412Sbostic  */
29*40412Sbostic 
3040411Sbostic #include	"lstInt.h"
3140411Sbostic 
3240411Sbostic /*-
3340411Sbostic  *-----------------------------------------------------------------------
3440411Sbostic  * Lst_DeQueue --
3540411Sbostic  *	Remove and return the datum at the head of the given list.
3640411Sbostic  *
3740411Sbostic  * Results:
3840411Sbostic  *	The datum in the node at the head or (ick) NIL if the list
3940411Sbostic  *	is empty.
4040411Sbostic  *
4140411Sbostic  * Side Effects:
4240411Sbostic  *	The head node is removed from the list.
4340411Sbostic  *
4440411Sbostic  *-----------------------------------------------------------------------
4540411Sbostic  */
4640411Sbostic ClientData
4740411Sbostic Lst_DeQueue (l)
4840411Sbostic     Lst	    	  l;
4940411Sbostic {
5040411Sbostic     ClientData	  rd;
5140411Sbostic     register ListNode	tln;
5240411Sbostic 
5340411Sbostic     tln = (ListNode) Lst_First (l);
5440411Sbostic     if (tln == NilListNode) {
5540411Sbostic 	return ((ClientData) NIL);
5640411Sbostic     }
5740411Sbostic 
5840411Sbostic     rd = tln->datum;
5940411Sbostic     if (Lst_Remove (l, (LstNode)tln) == FAILURE) {
6040411Sbostic 	return ((ClientData) NIL);
6140411Sbostic     } else {
6240411Sbostic 	return (rd);
6340411Sbostic     }
6440411Sbostic }
6540411Sbostic 
66