iter.h

   1 /*
   2  * Copyright 2005 Timo Hirvonen
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public License as
   6  * published by the Free Software Foundation; either version 2 of the
   7  * License, or (at your option) any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful, but
  10  * WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12  * General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, write to the Free Software
  16  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
  17  * 02111-1307, USA.
  18  */
  19
  20 #ifndef _ITER_H
  21 #define _ITER_H
  22
  23 #include <stdlib.h>
  24
  25 struct iter {
  26         /* this usually points to the list head */
  27         void *data0;
  28
  29         /* these point to the list item, for simple lists data2 is usually NULL */
  30         void *data1;
  31         void *data2;
  32 };
  33
  34 static inline void iter_init(struct iter *iter)
  35 {
  36         iter->data0 = NULL;
  37         iter->data1 = NULL;
  38         iter->data2 = NULL;
  39 }
  40
  41 static inline void iter_head(struct iter *iter)
  42 {
  43         iter->data1 = NULL;
  44         iter->data2 = NULL;
  45 }
  46
  47 static inline int iters_equal(struct iter *a, struct iter *b)
  48 {
  49         return a->data0 == b->data0 &&
  50                 a->data1 == b->data1 &&
  51                 a->data2 == b->data2;
  52 }
  53
  54 static inline int iter_is_head(struct iter *iter)
  55 {
  56         return iter->data0 != NULL &&
  57                 iter->data1 == NULL &&
  58                 iter->data2 == NULL;
  59 }
  60
  61 static inline int iter_is_null(struct iter *iter)
  62 {
  63         return iter->data0 == NULL &&
  64                 iter->data1 == NULL &&
  65                 iter->data2 == NULL;
  66 }
  67
  68 static inline int iter_is_empty(struct iter *iter)
  69 {
  70         return iter->data0 == NULL || (iter->data1 == NULL && iter->data2 == NULL);
  71 }
  72
  73 #define GENERIC_ITER_PREV(FUNC, TYPE, MEMBER)                           \
  74 int FUNC(struct iter *iter)                                             \
  75 {                                                                       \
  76         struct list_head *head = iter->data0;                           \
  77         TYPE *e = iter->data1;                                          \
  78                                                                         \
  79         if (head == NULL)                                               \
  80                 return 0;                                               \
  81         if (e == NULL) {                                                \
  82                 /* head, get last */                                    \
  83                 if (head->prev == head) {                               \
  84                         /* empty, iter points to the head already */    \
  85                         return 0;                                       \
  86                 }                                                       \
  87                 iter->data1 = container_of(head->prev, TYPE, MEMBER);   \
  88                 return 1;                                               \
  89         }                                                               \
  90         if (e->MEMBER.prev == head) {                                   \
  91                 iter->data1 = NULL;                                     \
  92                 return 0;                                               \
  93         }                                                               \
  94         iter->data1 = container_of(e->MEMBER.prev, TYPE, MEMBER);       \
  95         return 1;                                                       \
  96 }
  97
  98 #define GENERIC_ITER_NEXT(FUNC, TYPE, MEMBER)                           \
  99 int FUNC(struct iter *iter)                                             \
 100 {                                                                       \
 101         struct list_head *head = iter->data0;                           \
 102         TYPE *e = iter->data1;                                          \
 103                                                                         \
 104         if (head == NULL)                                               \
 105                 return 0;                                               \
 106         if (e == NULL) {                                                \
 107                 /* head, get first */                                   \
 108                 if (head->next == head) {                               \
 109                         /* empty, iter points to the head already */    \
 110                         return 0;                                       \
 111                 }                                                       \
 112                 iter->data1 = container_of(head->next, TYPE, MEMBER);   \
 113                 return 1;                                               \
 114         }                                                               \
 115         if (e->MEMBER.next == head) {                                   \
 116                 iter->data1 = NULL;                                     \
 117                 return 0;                                               \
 118         }                                                               \
 119         iter->data1 = container_of(e->MEMBER.next, TYPE, MEMBER);       \
 120         return 1;                                                       \
 121 }
 122
 123 #endif