Commit | Line | Data |
---|---|---|
15637ed4 RG |
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 | * | |
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. | |
35 | */ | |
36 | ||
37 | #ifndef lint | |
38 | static char sccsid[] = "@(#)lstConcat.c 5.3 (Berkeley) 6/1/90"; | |
39 | #endif /* not lint */ | |
40 | ||
41 | /*- | |
42 | * listConcat.c -- | |
43 | * Function to concatentate two lists. | |
44 | */ | |
45 | ||
46 | #include "lstInt.h" | |
47 | ||
48 | /*- | |
49 | *----------------------------------------------------------------------- | |
50 | * Lst_Concat -- | |
51 | * Concatenate two lists. New elements are created to hold the data | |
52 | * elements, if specified, but the elements themselves are not copied. | |
53 | * If the elements should be duplicated to avoid confusion with another | |
54 | * list, the Lst_Duplicate function should be called first. | |
55 | * If LST_CONCLINK is specified, the second list is destroyed since | |
56 | * its pointers have been corrupted and the list is no longer useable. | |
57 | * | |
58 | * Results: | |
59 | * SUCCESS if all went well. FAILURE otherwise. | |
60 | * | |
61 | * Side Effects: | |
62 | * New elements are created and appended the the first list. | |
63 | *----------------------------------------------------------------------- | |
64 | */ | |
65 | ReturnStatus | |
66 | Lst_Concat (l1, l2, flags) | |
67 | Lst l1; /* The list to which l2 is to be appended */ | |
68 | Lst l2; /* The list to append to l1 */ | |
69 | int flags; /* LST_CONCNEW if LstNode's should be duplicated | |
70 | * LST_CONCLINK if should just be relinked */ | |
71 | { | |
72 | register ListNode ln; /* original LstNode */ | |
73 | register ListNode nln; /* new LstNode */ | |
74 | register ListNode last; /* the last element in the list. Keeps | |
75 | * bookkeeping until the end */ | |
76 | register List list1 = (List)l1; | |
77 | register List list2 = (List)l2; | |
78 | ||
79 | if (!LstValid (l1) || !LstValid (l2)) { | |
80 | return (FAILURE); | |
81 | } | |
82 | ||
83 | if (flags == LST_CONCLINK) { | |
84 | if (list2->firstPtr != NilListNode) { | |
85 | /* | |
86 | * We set the nextPtr of the | |
87 | * last element of list two to be NIL to make the loop easier and | |
88 | * so we don't need an extra case should the first list turn | |
89 | * out to be non-circular -- the final element will already point | |
90 | * to NIL space and the first element will be untouched if it | |
91 | * existed before and will also point to NIL space if it didn't. | |
92 | */ | |
93 | list2->lastPtr->nextPtr = NilListNode; | |
94 | /* | |
95 | * So long as the second list isn't empty, we just link the | |
96 | * first element of the second list to the last element of the | |
97 | * first list. If the first list isn't empty, we then link the | |
98 | * last element of the list to the first element of the second list | |
99 | * The last element of the second list, if it exists, then becomes | |
100 | * the last element of the first list. | |
101 | */ | |
102 | list2->firstPtr->prevPtr = list1->lastPtr; | |
103 | if (list1->lastPtr != NilListNode) { | |
104 | list1->lastPtr->nextPtr = list2->firstPtr; | |
105 | } | |
106 | list1->lastPtr = list2->lastPtr; | |
107 | } | |
108 | if (list1->isCirc && list1->firstPtr != NilListNode) { | |
109 | /* | |
110 | * If the first list is supposed to be circular and it is (now) | |
111 | * non-empty, we must make sure it's circular by linking the | |
112 | * first element to the last and vice versa | |
113 | */ | |
114 | list1->firstPtr->prevPtr = list1->lastPtr; | |
115 | list1->lastPtr->nextPtr = list1->firstPtr; | |
116 | } | |
117 | free ((Address)l2); | |
118 | } else if (list2->firstPtr != NilListNode) { | |
119 | /* | |
120 | * We set the nextPtr of the last element of list 2 to be nil to make | |
121 | * the loop less difficult. The loop simply goes through the entire | |
122 | * second list creating new LstNodes and filling in the nextPtr, and | |
123 | * prevPtr to fit into l1 and its datum field from the | |
124 | * datum field of the corresponding element in l2. The 'last' node | |
125 | * follows the last of the new nodes along until the entire l2 has | |
126 | * been appended. Only then does the bookkeeping catch up with the | |
127 | * changes. During the first iteration of the loop, if 'last' is nil, | |
128 | * the first list must have been empty so the newly-created node is | |
129 | * made the first node of the list. | |
130 | */ | |
131 | list2->lastPtr->nextPtr = NilListNode; | |
132 | for (last = list1->lastPtr, ln = list2->firstPtr; | |
133 | ln != NilListNode; | |
134 | ln = ln->nextPtr) | |
135 | { | |
136 | PAlloc (nln, ListNode); | |
137 | nln->datum = ln->datum; | |
138 | if (last != NilListNode) { | |
139 | last->nextPtr = nln; | |
140 | } else { | |
141 | list1->firstPtr = nln; | |
142 | } | |
143 | nln->prevPtr = last; | |
144 | nln->flags = nln->useCount = 0; | |
145 | last = nln; | |
146 | } | |
147 | ||
148 | /* | |
149 | * Finish bookkeeping. The last new element becomes the last element | |
150 | * of list one. | |
151 | */ | |
152 | list1->lastPtr = last; | |
153 | ||
154 | /* | |
155 | * The circularity of both list one and list two must be corrected | |
156 | * for -- list one because of the new nodes added to it; list two | |
157 | * because of the alteration of list2->lastPtr's nextPtr to ease the | |
158 | * above for loop. | |
159 | */ | |
160 | if (list1->isCirc) { | |
161 | list1->lastPtr->nextPtr = list1->firstPtr; | |
162 | list1->firstPtr->prevPtr = list1->lastPtr; | |
163 | } else { | |
164 | last->nextPtr = NilListNode; | |
165 | } | |
166 | ||
167 | if (list2->isCirc) { | |
168 | list2->lastPtr->nextPtr = list2->firstPtr; | |
169 | } | |
170 | } | |
171 | ||
172 | return (SUCCESS); | |
173 | } | |
174 |