simple_list.h revision afb833d4e89c312460a4ab9ed6a7a8ca4ebbfe1c 
1/* $Id: simple_list.h,v 1.1 1999/08/19 00:55:41 jtg Exp $ */
2
3/*
4 * Mesa 3-D graphics library
5 * Version:  3.1
6 *
7 * Copyright (C) 1999  Brian Paul   All Rights Reserved.
8 *
9 * Permission is hereby granted, free of charge, to any person obtaining a
10 * copy of this software and associated documentation files (the "Software"),
11 * to deal in the Software without restriction, including without limitation
12 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
13 * and/or sell copies of the Software, and to permit persons to whom the
14 * Software is furnished to do so, subject to the following conditions:
15 *
16 * The above copyright notice and this permission notice shall be included
17 * in all copies or substantial portions of the Software.
18 *
19 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
20 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
21 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
22 * BRIAN PAUL BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
23 * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
24 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
25 */
26
27/*  Simple macros for typesafe, intrusive lists.
28 *  (C) 1997, Keith Whitwell
29 *
30 *  Intended to work with a list sentinal which is created as an empty
31 *  list.  Insert & delete are O(1).
32 */
33
34
35#ifndef _SIMPLE_LIST_H
36#define _SIMPLE_LIST_H
37
38#define remove_from_list(elem)			\
39do {						\
40   (elem)->next->prev = (elem)->prev;		\
41   (elem)->prev->next = (elem)->next;		\
42} while (0)
43
44#define insert_at_head(list, elem)		\
45do {						\
46   (elem)->prev = list;				\
47   (elem)->next = (list)->next;			\
48   (list)->next->prev = elem;			\
49   (list)->next = elem;				\
50} while(0)
51
52#define insert_at_tail(list, elem)		\
53do {						\
54   (elem)->next = list;				\
55   (elem)->prev = (list)->prev;			\
56   (list)->prev->next = elem;			\
57   (list)->prev = elem;				\
58} while(0)
59
60#define move_to_head(list, elem)		\
61do {						\
62   remove_from_list(elem);			\
63   insert_at_head(list, elem);			\
64} while (0)
65
66#define move_to_tail(list, elem)		\
67do {						\
68   remove_from_list(elem);			\
69   insert_at_tail(list, elem);			\
70} while (0)
71
72
73#define make_empty_list(sentinal)		\
74do {						\
75   (sentinal)->next = sentinal;			\
76   (sentinal)->prev = sentinal;			\
77} while (0)
78
79
80#define first_elem(list)       ((list)->next)
81#define last_elem(list)        ((list)->prev)
82#define next_elem(elem)        ((elem)->next)
83#define prev_elem(elem)        ((elem)->prev)
84#define at_end(list, elem)     ((elem) == (list))
85#define is_empty_list(list)    ((list)->next == (list))
86
87#define foreach(ptr, list)     \
88        for( ptr=(list)->next ;  ptr!=list ;  ptr=(ptr)->next )
89
90/* Kludgey - Lets you unlink the current value during a list
91 *           traversal.  Useful for free()-ing a list, element
92 *           by element.
93 */
94#define foreach_s(ptr, t, list)   \
95        for(ptr=(list)->next,t=(ptr)->next; list != ptr; ptr=t, t=(t)->next)
96
97
98#endif
99
100