1 /*
2  * Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC")
3  * Copyright (c) 1997,1999 by Internet Software Consortium.
4  *
5  * Permission to use, copy, modify, and distribute this software for any
6  * purpose with or without fee is hereby granted, provided that the above
7  * copyright notice and this permission notice appear in all copies.
8  *
9  * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES
10  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
11  * MERCHANTABILITY AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR
12  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
13  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
14  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
15  * OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
16  */
17 
18 #ifndef LIST_H
19 #define LIST_H 1
20 #include <isc/assertions.h>
21 
22 #define LIST(type) struct { type *head, *tail; }
23 #define INIT_LIST(list) \
24 	do { (list).head = NULL; (list).tail = NULL; } while (0)
25 
26 #define LINK(type) struct { type *prev, *next; }
27 #define INIT_LINK_TYPE(elt, link, type) \
28 	do { \
29 		(elt)->link.prev = (type *)(-1); \
30 		(elt)->link.next = (type *)(-1); \
31 	} while (0)
32 #define INIT_LINK(elt, link) \
33 	INIT_LINK_TYPE(elt, link, void)
34 #define LINKED(elt, link) ((void *)((elt)->link.prev) != (void *)(-1) && \
35 			   (void *)((elt)->link.next) != (void *)(-1))
36 
37 #define HEAD(list) ((list).head)
38 #define TAIL(list) ((list).tail)
39 #define EMPTY(list) ((list).head == NULL)
40 
41 #define PREPEND(list, elt, link) \
42 	do { \
43 		INSIST(!LINKED(elt, link));\
44 		if ((list).head != NULL) \
45 			(list).head->link.prev = (elt); \
46 		else \
47 			(list).tail = (elt); \
48 		(elt)->link.prev = NULL; \
49 		(elt)->link.next = (list).head; \
50 		(list).head = (elt); \
51 	} while (0)
52 
53 #define APPEND(list, elt, link) \
54 	do { \
55 		INSIST(!LINKED(elt, link));\
56 		if ((list).tail != NULL) \
57 			(list).tail->link.next = (elt); \
58 		else \
59 			(list).head = (elt); \
60 		(elt)->link.prev = (list).tail; \
61 		(elt)->link.next = NULL; \
62 		(list).tail = (elt); \
63 	} while (0)
64 
65 #define UNLINK_TYPE(list, elt, link, type) \
66 	do { \
67 		INSIST(LINKED(elt, link));\
68 		if ((elt)->link.next != NULL) \
69 			(elt)->link.next->link.prev = (elt)->link.prev; \
70 		else { \
71 			INSIST((list).tail == (elt)); \
72 			(list).tail = (elt)->link.prev; \
73 		} \
74 		if ((elt)->link.prev != NULL) \
75 			(elt)->link.prev->link.next = (elt)->link.next; \
76 		else { \
77 			INSIST((list).head == (elt)); \
78 			(list).head = (elt)->link.next; \
79 		} \
80 		INIT_LINK_TYPE(elt, link, type); \
81 	} while (0)
82 #define UNLINK(list, elt, link) \
83 	UNLINK_TYPE(list, elt, link, void)
84 
85 #define PREV(elt, link) ((elt)->link.prev)
86 #define NEXT(elt, link) ((elt)->link.next)
87 
88 #define INSERT_BEFORE(list, before, elt, link) \
89 	do { \
90 		INSIST(!LINKED(elt, link));\
91 		if ((before)->link.prev == NULL) \
92 			PREPEND(list, elt, link); \
93 		else { \
94 			(elt)->link.prev = (before)->link.prev; \
95 			(before)->link.prev = (elt); \
96 			(elt)->link.prev->link.next = (elt); \
97 			(elt)->link.next = (before); \
98 		} \
99 	} while (0)
100 
101 #define INSERT_AFTER(list, after, elt, link) \
102 	do { \
103 		INSIST(!LINKED(elt, link));\
104 		if ((after)->link.next == NULL) \
105 			APPEND(list, elt, link); \
106 		else { \
107 			(elt)->link.next = (after)->link.next; \
108 			(after)->link.next = (elt); \
109 			(elt)->link.next->link.prev = (elt); \
110 			(elt)->link.prev = (after); \
111 		} \
112 	} while (0)
113 
114 #define ENQUEUE(list, elt, link) APPEND(list, elt, link)
115 #define DEQUEUE(list, elt, link) UNLINK(list, elt, link)
116 
117 #endif /* LIST_H */
118 /*! \file */
119