180 lines
6.5 KiB
C
180 lines
6.5 KiB
C
/*
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* Copyright (c) 1988, 1989, 1990, 1993
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* The Regents of the University of California. All rights reserved.
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*
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* This code is derived from software contributed to Berkeley by
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* Adam de Boor.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by the University of
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* California, Berkeley and its contributors.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* @(#)lstConcat.c 8.1 (Berkeley) 6/6/93
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*/
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#ifndef lint
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#include <sys/cdefs.h>
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__RCSID("$FreeBSD$");
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#endif /* not lint */
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/*-
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* listConcat.c --
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* Function to concatentate two lists.
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*/
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#include "lstInt.h"
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/*-
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*-----------------------------------------------------------------------
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* Lst_Concat --
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* Concatenate two lists. New elements are created to hold the data
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* elements, if specified, but the elements themselves are not copied.
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* If the elements should be duplicated to avoid confusion with another
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* list, the Lst_Duplicate function should be called first.
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* If LST_CONCLINK is specified, the second list is destroyed since
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* its pointers have been corrupted and the list is no longer useable.
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*
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* Results:
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* SUCCESS if all went well. FAILURE otherwise.
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*
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* Side Effects:
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* New elements are created and appended the the first list.
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*-----------------------------------------------------------------------
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*/
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ReturnStatus
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Lst_Concat (l1, l2, flags)
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Lst l1; /* The list to which l2 is to be appended */
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Lst l2; /* The list to append to l1 */
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int flags; /* LST_CONCNEW if LstNode's should be duplicated
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* LST_CONCLINK if should just be relinked */
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{
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register ListNode ln; /* original LstNode */
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register ListNode nln; /* new LstNode */
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register ListNode last; /* the last element in the list. Keeps
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* bookkeeping until the end */
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register List list1 = (List)l1;
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register List list2 = (List)l2;
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if (!LstValid (l1) || !LstValid (l2)) {
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return (FAILURE);
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}
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if (flags == LST_CONCLINK) {
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if (list2->firstPtr != NULL) {
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/*
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* We set the nextPtr of the
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* last element of list two to be NULL to make the loop easier and
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* so we don't need an extra case should the first list turn
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* out to be non-circular -- the final element will already point
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* to NULL space and the first element will be untouched if it
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* existed before and will also point to NULL space if it didn't.
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*/
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list2->lastPtr->nextPtr = NULL;
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/*
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* So long as the second list isn't empty, we just link the
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* first element of the second list to the last element of the
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* first list. If the first list isn't empty, we then link the
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* last element of the list to the first element of the second list
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* The last element of the second list, if it exists, then becomes
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* the last element of the first list.
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*/
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list2->firstPtr->prevPtr = list1->lastPtr;
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if (list1->lastPtr != NULL) {
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list1->lastPtr->nextPtr = list2->firstPtr;
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} else {
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list1->firstPtr = list2->firstPtr;
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}
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list1->lastPtr = list2->lastPtr;
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}
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if (list1->isCirc && list1->firstPtr != NULL) {
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/*
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* If the first list is supposed to be circular and it is (now)
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* non-empty, we must make sure it's circular by linking the
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* first element to the last and vice versa
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*/
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list1->firstPtr->prevPtr = list1->lastPtr;
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list1->lastPtr->nextPtr = list1->firstPtr;
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}
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free (l2);
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} else if (list2->firstPtr != NULL) {
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/*
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* We set the nextPtr of the last element of list 2 to be NULL to make
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* the loop less difficult. The loop simply goes through the entire
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* second list creating new LstNodes and filling in the nextPtr, and
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* prevPtr to fit into l1 and its datum field from the
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* datum field of the corresponding element in l2. The 'last' node
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* follows the last of the new nodes along until the entire l2 has
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* been appended. Only then does the bookkeeping catch up with the
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* changes. During the first iteration of the loop, if 'last' is NULL,
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* the first list must have been empty so the newly-created node is
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* made the first node of the list.
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*/
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list2->lastPtr->nextPtr = NULL;
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for (last = list1->lastPtr, ln = list2->firstPtr;
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ln != NULL;
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ln = ln->nextPtr)
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{
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PAlloc (nln, ListNode);
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nln->datum = ln->datum;
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if (last != NULL) {
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last->nextPtr = nln;
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} else {
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list1->firstPtr = nln;
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}
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nln->prevPtr = last;
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nln->flags = nln->useCount = 0;
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last = nln;
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}
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/*
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* Finish bookkeeping. The last new element becomes the last element
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* of list one.
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*/
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list1->lastPtr = last;
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/*
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* The circularity of both list one and list two must be corrected
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* for -- list one because of the new nodes added to it; list two
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* because of the alteration of list2->lastPtr's nextPtr to ease the
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* above for loop.
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*/
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if (list1->isCirc) {
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list1->lastPtr->nextPtr = list1->firstPtr;
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list1->firstPtr->prevPtr = list1->lastPtr;
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} else {
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last->nextPtr = NULL;
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}
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if (list2->isCirc) {
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list2->lastPtr->nextPtr = list2->firstPtr;
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}
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}
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return (SUCCESS);
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}
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