1 /* $OpenBSD: lstConcat.c,v 1.20 2010/07/19 19:46:44 espie Exp $ */ 2 /* $NetBSD: lstConcat.c,v 1.6 1996/11/06 17:59:34 christos Exp $ */ 3 4 /* 5 * Copyright (c) 1988, 1989, 1990, 1993 6 * The Regents of the University of California. All rights reserved. 7 * 8 * This code is derived from software contributed to Berkeley by 9 * Adam de Boor. 10 * 11 * Redistribution and use in source and binary forms, with or without 12 * modification, are permitted provided that the following conditions 13 * are met: 14 * 1. Redistributions of source code must retain the above copyright 15 * notice, this list of conditions and the following disclaimer. 16 * 2. Redistributions in binary form must reproduce the above copyright 17 * notice, this list of conditions and the following disclaimer in the 18 * documentation and/or other materials provided with the distribution. 19 * 3. Neither the name of the University nor the names of its contributors 20 * may be used to endorse or promote products derived from this software 21 * without specific prior written permission. 22 * 23 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 24 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 25 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 26 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 27 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 28 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 29 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 30 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 31 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 32 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 33 * SUCH DAMAGE. 34 */ 35 36 /*- 37 * listConcat.c -- 38 * Function to copy a list and append it to another. 39 */ 40 41 #include "lstInt.h" 42 #include <sys/types.h> 43 #include <stddef.h> 44 #include "memory.h" 45 46 /*- 47 *----------------------------------------------------------------------- 48 * Lst_Concat -- 49 * Concatenate two lists. New elements are created to hold the data 50 * elements but the elements themselves are not copied. 51 * If the elements themselves should be duplicated to avoid 52 * confusion with another list, the Lst_Duplicate function 53 * should be called first. 54 * 55 * Side Effects: 56 * New elements are created and appended to the first list. 57 *----------------------------------------------------------------------- 58 */ 59 void 60 Lst_Concat(Lst l1, Lst l2) 61 { 62 LstNode ln; /* original LstNode */ 63 LstNode nln; /* new LstNode */ 64 LstNode last; /* the last element in the list. Keeps 65 * bookkeeping until the end */ 66 if (l2->firstPtr != NULL) { 67 /* The loop simply goes through the entire second list creating 68 * new LstNodes and filling in the nextPtr, and prevPtr to fit 69 * into l1 and its datum field from the datum field of the 70 * corresponding element in l2. The 'last' node follows the 71 * last of the new nodes along until the entire l2 has been 72 * appended. Only then does the bookkeeping catch up with the 73 * changes. During the first iteration of the loop, if 'last' 74 * is NULL, the first list must have been empty so the 75 * newly-created node is made the first node of the list. */ 76 for (last = l1->lastPtr, ln = l2->firstPtr; ln != NULL; 77 ln = ln->nextPtr) { 78 PAlloc(nln, LstNode); 79 nln->datum = ln->datum; 80 if (last != NULL) 81 last->nextPtr = nln; 82 else 83 l1->firstPtr = nln; 84 nln->prevPtr = last; 85 last = nln; 86 } 87 88 /* Finish bookkeeping. The last new element becomes the last 89 * element of l1. */ 90 l1->lastPtr = last; 91 last->nextPtr = NULL; 92 } 93 } 94 95