xref: /openbsd/usr.bin/make/lst.lib/lstDeQueue.c (revision 133306f0)
1 /*	$OpenBSD: lstDeQueue.c,v 1.10 2000/09/14 13:32:09 espie Exp $	*/
2 /*	$NetBSD: lstDeQueue.c,v 1.5 1996/11/06 17:59:36 christos Exp $	*/
3 
4 /*
5  * Copyright (c) 1988, 1989, 1990, 1993
6  *	The Regents of the University of California.  All rights reserved.
7  *
8  * This code is derived from software contributed to Berkeley by
9  * Adam de Boor.
10  *
11  * Redistribution and use in source and binary forms, with or without
12  * modification, are permitted provided that the following conditions
13  * are met:
14  * 1. Redistributions of source code must retain the above copyright
15  *    notice, this list of conditions and the following disclaimer.
16  * 2. Redistributions in binary form must reproduce the above copyright
17  *    notice, this list of conditions and the following disclaimer in the
18  *    documentation and/or other materials provided with the distribution.
19  * 3. All advertising materials mentioning features or use of this software
20  *    must display the following acknowledgement:
21  *	This product includes software developed by the University of
22  *	California, Berkeley and its contributors.
23  * 4. Neither the name of the University nor the names of its contributors
24  *    may be used to endorse or promote products derived from this software
25  *    without specific prior written permission.
26  *
27  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
28  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
29  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
30  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
31  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
32  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
33  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
34  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
35  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
36  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
37  * SUCH DAMAGE.
38  */
39 
40 /*-
41  * LstDeQueue.c --
42  *	Remove the node and return its datum from the head of the list
43  */
44 
45 #include	"lstInt.h"
46 #ifndef lint
47 #if 0
48 static char sccsid[] = "@(#)lstDeQueue.c	8.1 (Berkeley) 6/6/93";
49 #else
50 UNUSED
51 static char rcsid[] = "$OpenBSD: lstDeQueue.c,v 1.10 2000/09/14 13:32:09 espie Exp $";
52 #endif
53 #endif /* not lint */
54 
55 
56 /*-
57  *-----------------------------------------------------------------------
58  * Lst_DeQueue --
59  *	Remove and return the datum at the head of the given list.
60  *
61  * Results:
62  *	The datum in the node at the head or (ick) NULL if the list
63  *	is empty.
64  *
65  * Side Effects:
66  *	The head node is removed from the list.
67  *
68  *-----------------------------------------------------------------------
69  */
70 void *
71 Lst_DeQueue(l)
72     Lst	    	  	l;
73 {
74     void		*rd;
75     LstNode		tln;
76 
77     tln = Lst_First(l);
78     if (tln == NULL)
79 	return NULL;
80 
81     rd = tln->datum;
82     Lst_Remove(l, tln);
83     return rd;
84 }
85 
86