xref: /openbsd-src/usr.bin/make/lst.lib/lstConcat.c (revision bb4544df9ace63bacb4f113c781faab96bfc1dec)
1*bb4544dfSespie /*	$OpenBSD: lstConcat.c,v 1.20 2010/07/19 19:46:44 espie Exp $	*/
2789486c7Smillert /*	$NetBSD: lstConcat.c,v 1.6 1996/11/06 17:59:34 christos Exp $	*/
3df930be7Sderaadt 
4df930be7Sderaadt /*
5789486c7Smillert  * Copyright (c) 1988, 1989, 1990, 1993
6789486c7Smillert  *	The Regents of the University of California.  All rights reserved.
7df930be7Sderaadt  *
8df930be7Sderaadt  * This code is derived from software contributed to Berkeley by
9df930be7Sderaadt  * Adam de Boor.
10df930be7Sderaadt  *
11df930be7Sderaadt  * Redistribution and use in source and binary forms, with or without
12df930be7Sderaadt  * modification, are permitted provided that the following conditions
13df930be7Sderaadt  * are met:
14df930be7Sderaadt  * 1. Redistributions of source code must retain the above copyright
15df930be7Sderaadt  *    notice, this list of conditions and the following disclaimer.
16df930be7Sderaadt  * 2. Redistributions in binary form must reproduce the above copyright
17df930be7Sderaadt  *    notice, this list of conditions and the following disclaimer in the
18df930be7Sderaadt  *    documentation and/or other materials provided with the distribution.
19f75387cbSmillert  * 3. Neither the name of the University nor the names of its contributors
20df930be7Sderaadt  *    may be used to endorse or promote products derived from this software
21df930be7Sderaadt  *    without specific prior written permission.
22df930be7Sderaadt  *
23df930be7Sderaadt  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
24df930be7Sderaadt  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
25df930be7Sderaadt  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
26df930be7Sderaadt  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
27df930be7Sderaadt  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
28df930be7Sderaadt  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
29df930be7Sderaadt  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
30df930be7Sderaadt  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
31df930be7Sderaadt  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
32df930be7Sderaadt  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
33df930be7Sderaadt  * SUCH DAMAGE.
34df930be7Sderaadt  */
35df930be7Sderaadt 
36df930be7Sderaadt /*-
37df930be7Sderaadt  * listConcat.c --
3804ed836eSespie  *	Function to copy a list and append it to another.
39df930be7Sderaadt  */
40df930be7Sderaadt 
41df930be7Sderaadt #include "lstInt.h"
429d9c3e66Sespie #include <sys/types.h>
439d9c3e66Sespie #include <stddef.h>
44f7923656Sespie #include "memory.h"
4504ed836eSespie 
46df930be7Sderaadt /*-
47df930be7Sderaadt  *-----------------------------------------------------------------------
48df930be7Sderaadt  * Lst_Concat --
49df930be7Sderaadt  *	Concatenate two lists. New elements are created to hold the data
5004ed836eSespie  *	elements but the elements themselves are not copied.
5104ed836eSespie  *	If the elements themselves should be duplicated to avoid
5204ed836eSespie  *	confusion with another list, the Lst_Duplicate function
5304ed836eSespie  *	should be called first.
54df930be7Sderaadt  *
55df930be7Sderaadt  * Side Effects:
56ad2b054bSespie  *	New elements are created and appended to the first list.
57df930be7Sderaadt  *-----------------------------------------------------------------------
58df930be7Sderaadt  */
596cbd4985Sespie void
Lst_Concat(Lst l1,Lst l2)60ad2b054bSespie Lst_Concat(Lst l1, Lst l2)
61df930be7Sderaadt {
6218e775c1Sespie 	LstNode ln;	/* original LstNode */
6318e775c1Sespie 	LstNode nln;	/* new LstNode */
6418e775c1Sespie 	LstNode last;	/* the last element in the list. Keeps
65df930be7Sderaadt 			 * bookkeeping until the end */
6618e775c1Sespie 	if (l2->firstPtr != NULL) {
67d9792fdcSespie 		/* The loop simply goes through the entire second list creating
68d9792fdcSespie 		 * new LstNodes and filling in the nextPtr, and prevPtr to fit
69d9792fdcSespie 		 * into l1 and its datum field from the datum field of the
70d9792fdcSespie 		 * corresponding element in l2. The 'last' node follows the
71d9792fdcSespie 		 * last of the new nodes along until the entire l2 has been
72d9792fdcSespie 		 * appended.  Only then does the bookkeeping catch up with the
73d9792fdcSespie 		 * changes. During the first iteration of the loop, if 'last'
74d9792fdcSespie 		 * is NULL, the first list must have been empty so the
75d9792fdcSespie 		 * newly-created node is made the first node of the list.  */
76d9792fdcSespie 		for (last = l1->lastPtr, ln = l2->firstPtr; ln != NULL;
7718e775c1Sespie 		     ln = ln->nextPtr) {
7818e775c1Sespie 			PAlloc(nln, LstNode);
79df930be7Sderaadt 			nln->datum = ln->datum;
8018e775c1Sespie 			if (last != NULL)
81df930be7Sderaadt 				last->nextPtr = nln;
8218e775c1Sespie 			else
8318e775c1Sespie 				l1->firstPtr = nln;
84df930be7Sderaadt 			nln->prevPtr = last;
85df930be7Sderaadt 			last = nln;
86df930be7Sderaadt 		}
87df930be7Sderaadt 
88d9792fdcSespie 		/* Finish bookkeeping. The last new element becomes the last
89d9792fdcSespie 		 * element of l1.  */
9018e775c1Sespie 		l1->lastPtr = last;
91324380a3Sespie 		last->nextPtr = NULL;
92df930be7Sderaadt 	}
93df930be7Sderaadt }
94df930be7Sderaadt 
95