| 1 | /*
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| 2 | * Copyright (c) 1988, 1989, 1990, 1993
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| 3 | * The Regents of the University of California. All rights reserved.
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| 4 | *
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| 5 | * This code is derived from software contributed to Berkeley by
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| 6 | * Adam de Boor.
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| 7 | *
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| 8 | * Redistribution and use in source and binary forms, with or without
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| 9 | * modification, are permitted provided that the following conditions
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| 10 | * are met:
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| 11 | * 1. Redistributions of source code must retain the above copyright
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| 12 | * notice, this list of conditions and the following disclaimer.
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| 13 | * 2. Redistributions in binary form must reproduce the above copyright
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| 14 | * notice, this list of conditions and the following disclaimer in the
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| 15 | * documentation and/or other materials provided with the distribution.
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| 16 | * 3. All advertising materials mentioning features or use of this software
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| 17 | * must display the following acknowledgement:
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| 18 | * This product includes software developed by the University of
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| 19 | * California, Berkeley and its contributors.
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| 20 | * 4. Neither the name of the University nor the names of its contributors
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| 21 | * may be used to endorse or promote products derived from this software
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| 22 | * without specific prior written permission.
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| 23 | *
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| 24 | * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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| 25 | * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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| 26 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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| 27 | * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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| 28 | * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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| 29 | * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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| 30 | * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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| 31 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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| 32 | * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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| 33 | * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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| 34 | * SUCH DAMAGE.
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| 35 | *
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| 36 | * @(#)lstNext.c 8.1 (Berkeley) 6/6/93
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| 37 | */
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| 38 |
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| 39 | #ifndef lint
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| 40 | #include <sys/cdefs.h>
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| 41 | __FBSDID("$FreeBSD: src/usr.bin/make/lst.lib/lstNext.c,v 1.9 2002/10/09 02:00:22 jmallett Exp $");
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| 42 | #endif /* not lint */
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| 43 |
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| 44 | /*-
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| 45 | * LstNext.c --
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| 46 | * Return the next node for a list.
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| 47 | * The sequential functions access the list in a slightly different way.
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| 48 | * CurPtr points to their idea of the current node in the list and they
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| 49 | * access the list based on it. Because the list is circular, Lst_Next
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| 50 | * and Lst_Prev will go around the list forever. Lst_IsAtEnd must be
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| 51 | * used to determine when to stop.
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| 52 | */
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| 53 |
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| 54 | #include "lstInt.h"
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| 55 |
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| 56 | /*-
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| 57 | *-----------------------------------------------------------------------
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| 58 | * Lst_Next --
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| 59 | * Return the next node for the given list.
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| 60 | *
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| 61 | * Results:
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| 62 | * The next node or NULL if the list has yet to be opened. Also
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| 63 | * if the list is non-circular and the end has been reached, NULL
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| 64 | * is returned.
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| 65 | *
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| 66 | * Side Effects:
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| 67 | * the curPtr field is updated.
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| 68 | *
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| 69 | *-----------------------------------------------------------------------
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| 70 | */
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| 71 | LstNode
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| 72 | Lst_Next (l)
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| 73 | Lst l;
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| 74 | {
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| 75 | register ListNode tln;
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| 76 | register List list = (List)l;
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| 77 |
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| 78 | if ((LstValid (l) == FALSE) ||
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| 79 | (list->isOpen == FALSE)) {
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| 80 | return (NULL);
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| 81 | }
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| 82 |
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| 83 | list->prevPtr = list->curPtr;
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| 84 |
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| 85 | if (list->curPtr == NULL) {
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| 86 | if (list->atEnd == Unknown) {
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| 87 | /*
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| 88 | * If we're just starting out, atEnd will be Unknown.
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| 89 | * Then we want to start this thing off in the right
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| 90 | * direction -- at the start with atEnd being Middle.
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| 91 | */
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| 92 | list->curPtr = tln = list->firstPtr;
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| 93 | list->atEnd = Middle;
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| 94 | } else {
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| 95 | tln = NULL;
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| 96 | list->atEnd = Tail;
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| 97 | }
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| 98 | } else {
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| 99 | tln = list->curPtr->nextPtr;
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| 100 | list->curPtr = tln;
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| 101 |
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| 102 | if (tln == list->firstPtr || tln == NULL) {
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| 103 | /*
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| 104 | * If back at the front, then we've hit the end...
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| 105 | */
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| 106 | list->atEnd = Tail;
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| 107 | } else {
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| 108 | /*
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| 109 | * Reset to Middle if gone past first.
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| 110 | */
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| 111 | list->atEnd = Middle;
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| 112 | }
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| 113 | }
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| 114 |
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| 115 | return ((LstNode)tln);
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| 116 | }
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| 117 |
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