/*      $OpenBSD: lstConcatDestroy.c,v 1.12 2022/12/26 19:16:02 jmc 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 concatenate two lists.
 */

#include    "lstInt.h"
#include    <stddef.h>

/*-
 *-----------------------------------------------------------------------
 * Lst_ConcatDestroy --
 *      Concatenate two lists.  The elements of the second list are
 *      destructively added to the first list.  If the elements should
 *      be duplicated to avoid confusion with another list, the
 *      Lst_Duplicate function should be called first.
 *
 * Side Effects:
 *      The second list is destroyed.
 *-----------------------------------------------------------------------
 */
void
Lst_ConcatDestroy(Lst l1, Lst l2)
{
        if (l2->firstPtr != NULL) {
                /*
                 * So long as the second list isn't empty, we just link the
                 * first element of the second list to the last element of the
                 * first list. If the first list isn't empty, we then link the
                 * last element of the list to the first element of the second
                 * list The last element of the second list, if it exists, then
                 * becomes the last element of the first list.
                 */
                l2->firstPtr->prevPtr = l1->lastPtr;
                if (l1->lastPtr != NULL)
                        l1->lastPtr->nextPtr = l2->firstPtr;
                else
                        l1->firstPtr = l2->firstPtr;
                l1->lastPtr = l2->lastPtr;
        }
}