1 /** 2 * \file simple_list.h 3 * Simple macros for type-safe, intrusive lists. 4 * 5 * Intended to work with a list sentinal which is created as an empty 6 * list. Insert & delete are O(1). 7 * 8 * \author 9 * (C) 1997, Keith Whitwell 10 */ 11 12 /* 13 * Mesa 3-D graphics library 14 * Version: 3.5 15 * 16 * Copyright (C) 1999-2001 Brian Paul All Rights Reserved. 17 * 18 * Permission is hereby granted, free of charge, to any person obtaining a 19 * copy of this software and associated documentation files (the "Software"), 20 * to deal in the Software without restriction, including without limitation 21 * the rights to use, copy, modify, merge, publish, distribute, sublicense, 22 * and/or sell copies of the Software, and to permit persons to whom the 23 * Software is furnished to do so, subject to the following conditions: 24 * 25 * The above copyright notice and this permission notice shall be included 26 * in all copies or substantial portions of the Software. 27 * 28 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS 29 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 30 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL 31 * BRIAN PAUL BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN 32 * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN 33 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. 34 */ 35 36 37 #ifndef _SIMPLE_LIST_H 38 #define _SIMPLE_LIST_H 39 40 struct simple_node { 41 struct simple_node *next; 42 struct simple_node *prev; 43 }; 44 45 /** 46 * Remove an element from list. 47 * 48 * \param elem element to remove. 49 */ 50 #define remove_from_list(elem) \ 51 do { \ 52 (elem)->next->prev = (elem)->prev; \ 53 (elem)->prev->next = (elem)->next; \ 54 } while (0) 55 56 /** 57 * Insert an element to the list head. 58 * 59 * \param list list. 60 * \param elem element to insert. 61 */ 62 #define insert_at_head(list, elem) \ 63 do { \ 64 (elem)->prev = list; \ 65 (elem)->next = (list)->next; \ 66 (list)->next->prev = elem; \ 67 (list)->next = elem; \ 68 } while(0) 69 70 /** 71 * Insert an element to the list tail. 72 * 73 * \param list list. 74 * \param elem element to insert. 75 */ 76 #define insert_at_tail(list, elem) \ 77 do { \ 78 (elem)->next = list; \ 79 (elem)->prev = (list)->prev; \ 80 (list)->prev->next = elem; \ 81 (list)->prev = elem; \ 82 } while(0) 83 84 /** 85 * Move an element to the list head. 86 * 87 * \param list list. 88 * \param elem element to move. 89 */ 90 #define move_to_head(list, elem) \ 91 do { \ 92 remove_from_list(elem); \ 93 insert_at_head(list, elem); \ 94 } while (0) 95 96 /** 97 * Move an element to the list tail. 98 * 99 * \param list list. 100 * \param elem element to move. 101 */ 102 #define move_to_tail(list, elem) \ 103 do { \ 104 remove_from_list(elem); \ 105 insert_at_tail(list, elem); \ 106 } while (0) 107 108 /** 109 * Make a empty list empty. 110 * 111 * \param sentinal list (sentinal element). 112 */ 113 #define make_empty_list(sentinal) \ 114 do { \ 115 (sentinal)->next = sentinal; \ 116 (sentinal)->prev = sentinal; \ 117 } while (0) 118 119 /** 120 * Get list first element. 121 * 122 * \param list list. 123 * 124 * \return pointer to first element. 125 */ 126 #define first_elem(list) ((list)->next) 127 128 /** 129 * Get list last element. 130 * 131 * \param list list. 132 * 133 * \return pointer to last element. 134 */ 135 #define last_elem(list) ((list)->prev) 136 137 /** 138 * Get next element. 139 * 140 * \param elem element. 141 * 142 * \return pointer to next element. 143 */ 144 #define next_elem(elem) ((elem)->next) 145 146 /** 147 * Get previous element. 148 * 149 * \param elem element. 150 * 151 * \return pointer to previous element. 152 */ 153 #define prev_elem(elem) ((elem)->prev) 154 155 /** 156 * Test whether element is at end of the list. 157 * 158 * \param list list. 159 * \param elem element. 160 * 161 * \return non-zero if element is at end of list, or zero otherwise. 162 */ 163 #define at_end(list, elem) ((elem) == (list)) 164 165 /** 166 * Test if a list is empty. 167 * 168 * \param list list. 169 * 170 * \return non-zero if list empty, or zero otherwise. 171 */ 172 #define is_empty_list(list) ((list)->next == (list)) 173 174 /** 175 * Walk through the elements of a list. 176 * 177 * \param ptr pointer to the current element. 178 * \param list list. 179 * 180 * \note It should be followed by a { } block or a single statement, as in a \c 181 * for loop. 182 */ 183 #define foreach(ptr, list) \ 184 for( ptr=(list)->next ; ptr!=list ; ptr=(ptr)->next ) 185 186 /** 187 * Walk through the elements of a list. 188 * 189 * Same as #foreach but lets you unlink the current value during a list 190 * traversal. Useful for freeing a list, element by element. 191 * 192 * \param ptr pointer to the current element. 193 * \param t temporary pointer. 194 * \param list list. 195 * 196 * \note It should be followed by a { } block or a single statement, as in a \c 197 * for loop. 198 */ 199 #define foreach_s(ptr, t, list) \ 200 for(ptr=(list)->next,t=(ptr)->next; list != ptr; ptr=t, t=(t)->next) 201 202 #endif 203