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iter.h

/* 
 * Copyright 2005 Timo Hirvonen
 * 
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation; either version 2 of the
 * License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
 * 02111-1307, USA.
 */

#ifndef _ITER_H
#define _ITER_H

#include <stdlib.h>

00025 struct iter {
      /* this usually points to the list head */
      void *data0;

      /* these point to the list item, for simple lists data2 is usually NULL */
      void *data1;
      void *data2;
};

static inline void iter_init(struct iter *iter)
{
      iter->data0 = NULL;
      iter->data1 = NULL;
      iter->data2 = NULL;
}

static inline void iter_head(struct iter *iter)
{
      iter->data1 = NULL;
      iter->data2 = NULL;
}

static inline int iters_equal(struct iter *a, struct iter *b)
{
      return a->data0 == b->data0 &&
            a->data1 == b->data1 &&
            a->data2 == b->data2;
}

static inline int iter_is_head(struct iter *iter)
{
      return iter->data0 != NULL &&
            iter->data1 == NULL &&
            iter->data2 == NULL;
}

static inline int iter_is_null(struct iter *iter)
{
      return iter->data0 == NULL &&
            iter->data1 == NULL &&
            iter->data2 == NULL;
}

static inline int iter_is_empty(struct iter *iter)
{
      return iter->data0 == NULL || (iter->data1 == NULL && iter->data2 == NULL);
}

#define GENERIC_ITER_PREV(FUNC, TYPE, MEMBER)                     \
int FUNC(struct iter *iter)                                 \
{                                                     \
      struct list_head *head = iter->data0;                       \
      TYPE *e = iter->data1;                                \
                                                      \
      if (head == NULL)                               \
            return 0;                                 \
      if (e == NULL) {                                \
            /* head, get last */                            \
            if (head->prev == head) {                       \
                  /* empty, iter points to the head already */    \
                  return 0;                           \
            }                                         \
            iter->data1 = container_of(head->prev, TYPE, MEMBER); \
            return 1;                                 \
      }                                               \
      if (e->MEMBER.prev == head) {                         \
            iter->data1 = NULL;                             \
            return 0;                                 \
      }                                               \
      iter->data1 = container_of(e->MEMBER.prev, TYPE, MEMBER);   \
      return 1;                                       \
}

#define GENERIC_ITER_NEXT(FUNC, TYPE, MEMBER)                     \
int FUNC(struct iter *iter)                                 \
{                                                     \
      struct list_head *head = iter->data0;                       \
      TYPE *e = iter->data1;                                \
                                                      \
      if (head == NULL)                               \
            return 0;                                 \
      if (e == NULL) {                                \
            /* head, get first */                           \
            if (head->next == head) {                       \
                  /* empty, iter points to the head already */    \
                  return 0;                           \
            }                                         \
            iter->data1 = container_of(head->next, TYPE, MEMBER); \
            return 1;                                 \
      }                                               \
      if (e->MEMBER.next == head) {                         \
            iter->data1 = NULL;                             \
            return 0;                                 \
      }                                               \
      iter->data1 = container_of(e->MEMBER.next, TYPE, MEMBER);   \
      return 1;                                       \
}

#endif

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