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1 | /* |
2 | * Copyright (c) 1988, 1989, 1990 The Regents of the University of California. | |
3 | * All rights reserved. | |
4 | * | |
5 | * This code is derived from software contributed to Berkeley by | |
6 | * Adam de Boor. | |
7 | * | |
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8 | * Redistribution and use in source and binary forms, with or without |
9 | * modification, are permitted provided that the following conditions | |
10 | * are met: | |
11 | * 1. Redistributions of source code must retain the above copyright | |
12 | * notice, this list of conditions and the following disclaimer. | |
13 | * 2. Redistributions in binary form must reproduce the above copyright | |
14 | * notice, this list of conditions and the following disclaimer in the | |
15 | * documentation and/or other materials provided with the distribution. | |
16 | * 3. All advertising materials mentioning features or use of this software | |
17 | * must display the following acknowledgement: | |
18 | * This product includes software developed by the University of | |
19 | * California, Berkeley and its contributors. | |
20 | * 4. Neither the name of the University nor the names of its contributors | |
21 | * may be used to endorse or promote products derived from this software | |
22 | * without specific prior written permission. | |
23 | * | |
24 | * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND | |
25 | * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE | |
26 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE | |
27 | * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE | |
28 | * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL | |
29 | * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS | |
30 | * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) | |
31 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT | |
32 | * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY | |
33 | * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF | |
34 | * SUCH DAMAGE. | |
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35 | */ |
36 | ||
37 | #ifndef lint | |
1c15e888 | 38 | static char sccsid[] = "@(#)lstOpen.c 5.3 (Berkeley) 6/1/90"; |
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39 | #endif /* not lint */ |
40 | ||
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41 | /*- |
42 | * LstOpen.c -- | |
43 | * Open a list for sequential access. The sequential functions access the | |
44 | * list in a slightly different way. CurPtr points to their idea of the | |
45 | * current node in the list and they access the list based on it. | |
46 | * If the list is circular, Lst_Next and Lst_Prev will go around | |
47 | * the list forever. Lst_IsAtEnd must be used to determine when to stop. | |
c65fedcf | 48 | */ |
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49 | |
50 | #include "lstInt.h" | |
51 | ||
52 | /*- | |
53 | *----------------------------------------------------------------------- | |
54 | * Lst_Open -- | |
55 | * Open a list for sequential access. A list can still be searched, | |
56 | * etc., without confusing these functions. | |
57 | * | |
58 | * Results: | |
59 | * SUCCESS or FAILURE. | |
60 | * | |
61 | * Side Effects: | |
62 | * isOpen is set TRUE and curPtr is set to NilListNode so the | |
63 | * other sequential functions no it was just opened and can choose | |
64 | * the first element accessed based on this. | |
65 | * | |
66 | *----------------------------------------------------------------------- | |
67 | */ | |
68 | ReturnStatus | |
69 | Lst_Open (l) | |
70 | register Lst l; | |
71 | { | |
72 | if (LstValid (l) == FALSE) { | |
73 | return (FAILURE); | |
74 | } | |
75 | ((List) l)->isOpen = TRUE; | |
76 | ((List) l)->atEnd = LstIsEmpty (l) ? Head : Unknown; | |
77 | ((List) l)->curPtr = NilListNode; | |
78 | ||
79 | return (SUCCESS); | |
80 | } | |
81 |