projects / unix-history / blame
| Commit | Line | Data |
|---|---|---|
| bb2109e7 | 1 | /* |
| 4f703748 KB |
2 | * Copyright (c) 1988, 1989, 1990, 1993 |
| 3 | * The Regents of the University of California. All rights reserved. | |
| c65fedcf | 4 | * |
| bb2109e7 KB |
5 | * This code is derived from software contributed to Berkeley by |
| 6 | * Adam de Boor. | |
| c65fedcf | 7 | * |
| f15db449 | 8 | * %sccs.include.redist.c% |
| c65fedcf | 9 | */ |
| bb2109e7 | 10 | |
| c65fedcf | 11 | #ifndef lint |
| bfdbffbb | 12 | static char sccsid[] = "@(#)lstInsert.c 8.2 (Berkeley) %G%"; |
| bb2109e7 KB |
13 | #endif /* not lint */ |
| 14 | ||
| 15 | /*- | |
| 16 | * LstInsert.c -- | |
| 17 | * Insert a new datum before an old one | |
| 18 | */ | |
| c65fedcf KB |
19 | |
| 20 | #include "lstInt.h" | |
| 21 | ||
| 22 | /*- | |
| 23 | *----------------------------------------------------------------------- | |
| 24 | * Lst_Insert -- | |
| 25 | * Insert a new node with the given piece of data before the given | |
| 26 | * node in the given list. | |
| 27 | * | |
| 28 | * Results: | |
| 29 | * SUCCESS or FAILURE. | |
| 30 | * | |
| 31 | * Side Effects: | |
| 32 | * the firstPtr field will be changed if ln is the first node in the | |
| 33 | * list. | |
| 34 | * | |
| 35 | *----------------------------------------------------------------------- | |
| 36 | */ | |
| 37 | ReturnStatus | |
| 38 | Lst_Insert (l, ln, d) | |
| 39 | Lst l; /* list to manipulate */ | |
| 40 | LstNode ln; /* node before which to insert d */ | |
| 41 | ClientData d; /* datum to be inserted */ | |
| 42 | { | |
| 43 | register ListNode nLNode; /* new lnode for d */ | |
| 44 | register ListNode lNode = (ListNode)ln; | |
| 45 | register List list = (List)l; | |
| 46 | ||
| 47 | ||
| 48 | /* | |
| 49 | * check validity of arguments | |
| 50 | */ | |
| 51 | if (LstValid (l) && (LstIsEmpty (l) && ln == NILLNODE)) | |
| 52 | goto ok; | |
| 53 | ||
| 54 | if (!LstValid (l) || LstIsEmpty (l) || !LstNodeValid (ln, l)) { | |
| 55 | return (FAILURE); | |
| 56 | } | |
| 57 | ||
| 58 | ok: | |
| 59 | PAlloc (nLNode, ListNode); | |
| 60 | ||
| 61 | nLNode->datum = d; | |
| 62 | nLNode->useCount = nLNode->flags = 0; | |
| 63 | ||
| 64 | if (ln == NILLNODE) { | |
| 65 | if (list->isCirc) { | |
| 66 | nLNode->prevPtr = nLNode->nextPtr = nLNode; | |
| 67 | } else { | |
| 68 | nLNode->prevPtr = nLNode->nextPtr = NilListNode; | |
| 69 | } | |
| 70 | list->firstPtr = list->lastPtr = nLNode; | |
| 71 | } else { | |
| 72 | nLNode->prevPtr = lNode->prevPtr; | |
| 73 | nLNode->nextPtr = lNode; | |
| 74 | ||
| 75 | if (nLNode->prevPtr != NilListNode) { | |
| 76 | nLNode->prevPtr->nextPtr = nLNode; | |
| 77 | } | |
| 78 | lNode->prevPtr = nLNode; | |
| 79 | ||
| 80 | if (lNode == list->firstPtr) { | |
| 81 | list->firstPtr = nLNode; | |
| 82 | } | |
| 83 | } | |
| 84 | ||
| 85 | return (SUCCESS); | |
| 86 | } | |
| 87 |