xref: /openbsd-src/usr.bin/make/lst.lib/lstConcat.c (revision bb4544df9ace63bacb4f113c781faab96bfc1dec)

/*	$OpenBSD: lstConcat.c,v 1.20 2010/07/19 19:46:44 espie Exp $	*/
/*	$NetBSD: lstConcat.c,v 1.6 1996/11/06 17:59:34 christos Exp $	*/

/*
 * Copyright (c) 1988, 1989, 1990, 1993
 *	The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Adam de Boor.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

/*-
 * listConcat.c --
 *	Function to copy a list and append it to another.
 */

#include "lstInt.h"
#include <sys/types.h>
#include <stddef.h>
#include "memory.h"

/*-
 *-----------------------------------------------------------------------
 * Lst_Concat --
 *	Concatenate two lists. New elements are created to hold the data
 *	elements but the elements themselves are not copied.
 *	If the elements themselves should be duplicated to avoid
 *	confusion with another list, the Lst_Duplicate function
 *	should be called first.
 *
 * Side Effects:
 *	New elements are created and appended to the first list.
 *-----------------------------------------------------------------------
 */
void
Lst_Concat(Lst l1, Lst l2)
{
	LstNode ln;	/* original LstNode */
	LstNode nln;	/* new LstNode */
	LstNode last;	/* the last element in the list. Keeps
			 * bookkeeping until the end */
	if (l2->firstPtr != NULL) {
		/* The loop simply goes through the entire second list creating
		 * new LstNodes and filling in the nextPtr, and prevPtr to fit
		 * into l1 and its datum field from the datum field of the
		 * corresponding element in l2. The 'last' node follows the
		 * last of the new nodes along until the entire l2 has been
		 * appended.  Only then does the bookkeeping catch up with the
		 * changes. During the first iteration of the loop, if 'last'
		 * is NULL, the first list must have been empty so the
		 * newly-created node is made the first node of the list.  */
		for (last = l1->lastPtr, ln = l2->firstPtr; ln != NULL;
		     ln = ln->nextPtr) {
			PAlloc(nln, LstNode);
			nln->datum = ln->datum;
			if (last != NULL)
				last->nextPtr = nln;
			else
				l1->firstPtr = nln;
			nln->prevPtr = last;
			last = nln;
		}

		/* Finish bookkeeping. The last new element becomes the last
		 * element of l1.  */
		l1->lastPtr = last;
		last->nextPtr = NULL;
	}
}