1d614caea7
now that their size is only two pointers. This eliminates a lot of calls to Lst_Init and from there to malloc together with many calls to Lst_Destroy (in places where the list is obviously empty). This also reduces the chance to leave a list uninitilized so we can remove more NULL pointer checks and probably eliminates a couple of memory leaks.
136 lines
4.8 KiB
C
136 lines
4.8 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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__FBSDID("$FreeBSD$");
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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 "make.h"
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#include "lst.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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*
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* Results:
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* SUCCESS if all went well. FAILURE otherwise.
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*
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* Arguments:
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* list1 The list to which list2 is to be appended
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* list2 The list to append to list1
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* 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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* 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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void
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Lst_Concat(Lst *list1, Lst *list2, int flags)
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{
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LstNode *ln; /* original LstNode */
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LstNode *nln; /* new LstNode */
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LstNode *last; /* the last element in the list. Keeps
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* bookkeeping until the end */
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if (list2->firstPtr == NULL)
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return;
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if (flags == LST_CONCLINK) {
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/*
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* Link the 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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list1->lastPtr = list2->lastPtr;
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Lst_Init(list2);
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} else {
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/*
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* 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 list1 and its datum field from the
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* datum field of the corresponding element in list2. The 'last' node
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* follows the last of the new nodes along until the entire list2 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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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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nln = emalloc(sizeof(*nln));
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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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last->nextPtr = NULL;
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}
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}
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