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 "debug.h"
  24
  25 #include <stdlib.h>
  26
  27 struct iter {
  28         /* this usually points to the list head */
  29         void *data0;
  30
  31         /* these point to the list item, for simple lists data2 is usually NULL */
  32         void *data1;
  33         void *data2;
  34 };
  35
  36 static inline void iter_init(struct iter *iter)
  37 {
  38         iter->data0 = NULL;
  39         iter->data1 = NULL;
  40         iter->data2 = NULL;
  41 }
  42
  43 static inline void iter_head(struct iter *iter)
  44 {
  45         iter->data1 = NULL;
  46         iter->data2 = NULL;
  47 }
  48
  49 static inline int iters_equal(struct iter *a, struct iter *b)
  50 {
  51         return a->data0 == b->data0 &&
  52                 a->data1 == b->data1 &&
  53                 a->data2 == b->data2;
  54 }
  55
  56 static inline int iter_is_head(struct iter *iter)
  57 {
  58         return iter->data0 != NULL &&
  59                 iter->data1 == NULL &&
  60                 iter->data2 == NULL;
  61 }
  62
  63 static inline int iter_is_null(struct iter *iter)
  64 {
  65         return iter->data0 == NULL &&
  66                 iter->data1 == NULL &&
  67                 iter->data2 == NULL;
  68 }
  69
  70 static inline int iter_is_empty(struct iter *iter)
  71 {
  72         return iter->data0 == NULL || (iter->data1 == NULL && iter->data2 == NULL);
  73 }
  74
  75 #define GENERIC_ITER_PREV(FUNC, TYPE, MEMBER)                           \
  76 int FUNC(struct iter *iter)                                             \
  77 {                                                                       \
  78         struct list_head *head = iter->data0;                           \
  79         TYPE *e = iter->data1;                                          \
  80                                                                         \
  81         BUG_ON(iter->data2);                                            \
  82         if (head == NULL)                                               \
  83                 return 0;                                               \
  84         if (e == NULL) {                                                \
  85                 /* head, get last */                                    \
  86                 if (head->prev == head) {                               \
  87                         /* empty, iter points to the head already */    \
  88                         return 0;                                       \
  89                 }                                                       \
  90                 iter->data1 = container_of(head->prev, TYPE, MEMBER);   \
  91                 return 1;                                               \
  92         }                                                               \
  93         if (e->MEMBER.prev == head) {                                   \
  94                 iter->data1 = NULL;                                     \
  95                 return 0;                                               \
  96         }                                                               \
  97         iter->data1 = container_of(e->MEMBER.prev, TYPE, MEMBER);       \
  98         return 1;                                                       \
  99 }
 100
 101 #define GENERIC_ITER_NEXT(FUNC, TYPE, MEMBER)                           \
 102 int FUNC(struct iter *iter)                                             \
 103 {                                                                       \
 104         struct list_head *head = iter->data0;                           \
 105         TYPE *e = iter->data1;                                          \
 106                                                                         \
 107         BUG_ON(iter->data2);                                            \
 108         if (head == NULL)                                               \
 109                 return 0;                                               \
 110         if (e == NULL) {                                                \
 111                 /* head, get first */                                   \
 112                 if (head->next == head) {                               \
 113                         /* empty, iter points to the head already */    \
 114                         return 0;                                       \
 115                 }                                                       \
 116                 iter->data1 = container_of(head->next, TYPE, MEMBER);   \
 117                 return 1;                                               \
 118         }                                                               \
 119         if (e->MEMBER.next == head) {                                   \
 120                 iter->data1 = NULL;                                     \
 121                 return 0;                                               \
 122         }                                                               \
 123         iter->data1 = container_of(e->MEMBER.next, TYPE, MEMBER);       \
 124         return 1;                                                       \
 125 }
 126
 127 #endif