/* $NetBSD: lstConcat.c,v 1.5 1995/06/14 15:20:53 christos Exp $ */ /* * Copyright (c) 1988, 1989, 1990 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. */ #ifndef lint #if 0 static char sccsid[] = "@(#)lstConcat.c 5.3 (Berkeley) 6/1/90"; #else static char rcsid[] = "$NetBSD: lstConcat.c,v 1.5 1995/06/14 15:20:53 christos Exp $"; #endif #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); }