/*      $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;
        }
}