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/*
* 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. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the University of
* California, Berkeley and its contributors.
* 4. 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.
*
* $FreeBSD$
*/
#ifndef lint
static char sccsid[] = "@(#)lstConcat.c 8.1 (Berkeley) 6/6/93";
#endif /* not lint */
/*-
* listConcat.c --
* Function to concatentate two lists.
*/
#include "lstInt.h"
/*-
*-----------------------------------------------------------------------
* Lst_Concat --
* Concatenate two lists. New elements are created to hold the data
* elements, if specified, but the elements themselves are not copied.
* If the elements should be duplicated to avoid confusion with another
* list, the Lst_Duplicate function should be called first.
* If LST_CONCLINK is specified, the second list is destroyed since
* its pointers have been corrupted and the list is no longer useable.
*
* Results:
* SUCCESS if all went well. FAILURE otherwise.
*
* Side Effects:
* New elements are created and appended the the first list.
*-----------------------------------------------------------------------
*/
ReturnStatus
Lst_Concat (l1, l2, flags)
Lst l1; /* The list to which l2 is to be appended */
Lst l2; /* The list to append to l1 */
int flags; /* LST_CONCNEW if LstNode's should be duplicated
* LST_CONCLINK if should just be relinked */
{
register ListNode ln; /* original LstNode */
register ListNode nln; /* new LstNode */
register ListNode last; /* the last element in the list. Keeps
* bookkeeping until the end */
register List list1 = (List)l1;
register List list2 = (List)l2;
if (!LstValid (l1) || !LstValid (l2)) {
return (FAILURE);
}
if (flags == LST_CONCLINK) {
if (list2->firstPtr != NilListNode) {
/*
* We set the nextPtr of the
* last element of list two to be NIL to make the loop easier and
* so we don't need an extra case should the first list turn
* out to be non-circular -- the final element will already point
* to NIL space and the first element will be untouched if it
* existed before and will also point to NIL space if it didn't.
*/
list2->lastPtr->nextPtr = NilListNode;
/*
* 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.
*/
list2->firstPtr->prevPtr = list1->lastPtr;
if (list1->lastPtr != NilListNode) {
list1->lastPtr->nextPtr = list2->firstPtr;
} else {
list1->firstPtr = list2->firstPtr;
}
list1->lastPtr = list2->lastPtr;
}
if (list1->isCirc && list1->firstPtr != NilListNode) {
/*
* If the first list is supposed to be circular and it is (now)
* non-empty, we must make sure it's circular by linking the
* first element to the last and vice versa
*/
list1->firstPtr->prevPtr = list1->lastPtr;
list1->lastPtr->nextPtr = list1->firstPtr;
}
free ((Address)l2);
} else if (list2->firstPtr != NilListNode) {
/*
* We set the nextPtr of the last element of list 2 to be nil to make
* the loop less difficult. 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 nil,
* the first list must have been empty so the newly-created node is
* made the first node of the list.
*/
list2->lastPtr->nextPtr = NilListNode;
for (last = list1->lastPtr, ln = list2->firstPtr;
ln != NilListNode;
ln = ln->nextPtr)
{
PAlloc (nln, ListNode);
nln->datum = ln->datum;
if (last != NilListNode) {
last->nextPtr = nln;
} else {
list1->firstPtr = nln;
}
nln->prevPtr = last;
nln->flags = nln->useCount = 0;
last = nln;
}
/*
* Finish bookkeeping. The last new element becomes the last element
* of list one.
*/
list1->lastPtr = last;
/*
* The circularity of both list one and list two must be corrected
* for -- list one because of the new nodes added to it; list two
* because of the alteration of list2->lastPtr's nextPtr to ease the
* above for loop.
*/
if (list1->isCirc) {
list1->lastPtr->nextPtr = list1->firstPtr;
list1->firstPtr->prevPtr = list1->lastPtr;
} else {
last->nextPtr = NilListNode;
}
if (list2->isCirc) {
list2->lastPtr->nextPtr = list2->firstPtr;
}
}
return (SUCCESS);
}
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