/* EINA - EFL data type library
 * Copyright (C) 2002-2008 Carsten Haitzler, Gustavo Sverzut Barbieri, Tilman Sauerbeck,
 *                         Vincent Torri, Cedric Bail, Jorge Luis Zapata Muga,
 *                         Corey Donohoe
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library;
 * if not, see <http://www.gnu.org/licenses/>.
 *
 * This file incorporates work covered by the following copyright and
 * permission notice:
 *
 * Copyright (C) 2004 ncn
 * Copyright (C) 2006 Sebastian Dransfeld
 * Copyright (C) 2007 Christopher Michael
 *
 *  Permission is hereby granted, free of charge, to any person obtaining a copy
 *  of this software and associated documentation files (the "Software"), to
 *  deal in the Software without restriction, including without limitation the
 *  rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
 *  sell copies of the Software, and to permit persons to whom the Software is
 *  furnished to do so, subject to the following conditions:

 *  The above copyright notice and this permission notice shall be included in
 *  all copies of the Software and its Copyright notices. In addition publicly
 *  documented acknowledgment must be given that this software has been used if no
 *  source code of this software is made available publicly. This includes
 *  acknowledgments in either Copyright notices, Manuals, Publicity and Marketing
 *  documents or any documentation provided with any product containing this
 *  software. This License does not apply to any software that links to the
 *  libraries provided by this software (statically or dynamically), but only to
 *  the software provided.

 *  Please see the OLD-COPYING.PLAIN for a plain-english explanation of this notice
 *  and it's intent.

 *  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 *  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 *  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
 *  THE AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
 *  IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
 *  CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */


/**
 * @page tutorial_list_page List Tutorial
 *
 * to be written...
 *
 */

#ifdef HAVE_CONFIG_H
# include "config.h"
#endif

#include <assert.h>

#include "eina_error.h"
#include "eina_list.h"
#include "eina_private.h"

/*============================================================================*
 *                                  Local                                     *
 *============================================================================*/

/**
 * @cond LOCAL
 */

typedef struct _Eina_Iterator_List Eina_Iterator_List;
typedef struct _Eina_Accessor_List Eina_Accessor_List;

struct _Eina_Iterator_List
{
   Eina_Iterator iterator;

   const Eina_List *head;
   const Eina_List *current;
};

struct _Eina_Accessor_List
{
   Eina_Accessor accessor;

   const Eina_List *head;
   const Eina_List *current;

   unsigned int index;
};

static inline Eina_List_Accounting*
_eina_list_mempool_accounting_new(__UNUSED__ Eina_List *list)
{
   Eina_List_Accounting *tmp;

   tmp = malloc(sizeof (Eina_List_Accounting));
   if (!tmp) eina_error_set(EINA_ERROR_OUT_OF_MEMORY);

   return tmp;
}
static inline void
_eina_list_mempool_accounting_free(Eina_List_Accounting *accounting)
{
   free(accounting);
}

static inline Eina_List*
_eina_list_mempool_list_new(__UNUSED__ Eina_List *list)
{
   Eina_List *tmp;

   tmp = malloc(sizeof (Eina_List));
   if (!tmp) eina_error_set(EINA_ERROR_OUT_OF_MEMORY);

   return tmp;
}
static inline void
_eina_list_mempool_list_free(Eina_List *list)
{
   list->accounting->count--;
   if (list->accounting->count == 0)
     _eina_list_mempool_accounting_free(list->accounting);

   free(list);
}

static Eina_List *
_eina_list_setup_accounting(Eina_List *list)
{
   list->accounting = _eina_list_mempool_accounting_new(list);
   if (!list->accounting) goto on_error;

   list->accounting->last = list;
   list->accounting->count = 1;

   return list;

 on_error:
   _eina_list_mempool_list_free(list);
   return NULL;
}

static inline void
_eina_list_update_accounting(Eina_List *list, Eina_List *new_list)
{
   list->accounting->count++;
   new_list->accounting = list->accounting;
}

#if 0
static Eina_Mempool2 _eina_list_mempool =
{
   sizeof(Eina_List),
   320,
   0, NULL, NULL
};
static Eina_Mempool2 _eina_list_accounting_mempool =
{
   sizeof(Eina_List_Accounting),
   80,
   0, NULL, NULL
};
#endif

static Eina_Bool
eina_list_iterator_next(Eina_Iterator_List *it, void **data)
{
   if (it->current == NULL) return EINA_FALSE;
   if (data) *data = eina_list_data(it->current);

   it->current = eina_list_next(it->current);

   return EINA_TRUE;
}

static Eina_List *
eina_list_iterator_get_container(Eina_Iterator_List *it)
{
   return (Eina_List *) it->head;
}

static void
eina_list_iterator_free(Eina_Iterator_List *it)
{
   free(it);
}

static Eina_Bool
eina_list_accessor_get_at(Eina_Accessor_List *it, unsigned int index, void **data)
{
   const Eina_List *over;
   unsigned int middle;
   unsigned int i;

   if (index > eina_list_count(it->head)) return EINA_FALSE;

   if (it->index == index)
     {
	over = it->current;
     }
   else if (index > it->index)
     {
	/* After current position. */
	middle = ((eina_list_count(it->head) - it->index) >> 1) + it->index;

	if (index > middle)
	  {
	     /* Go backward from the end. */
	     for (i = eina_list_count(it->head) - 1, over = eina_list_last(it->head);
		  i > index && over != NULL;
		  --i, over = eina_list_prev(over))
	       ;
	  }
	else
	  {
	     /* Go forward from current. */
	     for (i = it->index, over = it->current;
		  i < index && over != NULL;
		  ++i, over = eina_list_next(over))
	       ;
	  }
     }
   else
     {
	/* Before current position. */
	middle = it->index >> 1;

	if (index > middle)
	  {
	     /* Go backward from current. */
	     for (i = it->index, over = it->current;
		  i > index && over != NULL;
		  --i, over = eina_list_prev(over))
	       ;
	  }
	else
	  {
	     /* Go forward from start. */
	     for (i = 0, over = it->head;
		  i < index && over != NULL;
		  ++i, over = eina_list_next(over))
	       ;
	  }
     }

   if (over == NULL) return EINA_FALSE;

   it->current = over;
   it->index = index;

   if (data) *data = eina_list_data(it->current);
   return EINA_TRUE;
}

static Eina_List *
eina_list_accessor_get_container(Eina_Accessor_List *it)
{
   return (Eina_List *) it->head;
}

static void
eina_list_accessor_free(Eina_Accessor_List *it)
{
   free(it);
}

/**
 * @endcond
 */

/*============================================================================*
 *                                 Global                                     *
 *============================================================================*/

/*============================================================================*
 *                                   API                                      *
 *============================================================================*/

/**
 * @addtogroup Eina_List_Group List
 *
 * @brief These functions provide single linked list management.
 *
 * For more information, you can look at the @ref tutorial_list_page.
 *
 * @{
 */

/**
 * @brief Initialize the list module.
 *
 * @return 1 or greater on success, 0 on error.
 *
 * This function just sets up the error module or Eina. It is also
 * called by eina_init(). It returns 0 on failure, otherwise it
 * returns the number of times eina_error_init() has already been
 * called.
 */
EAPI int
eina_list_init(void)
{
   return eina_error_init();
}

/**
 * @brief Shut down the list module.
 *
 * @return 0 when the error module is completely shut down, 1 or
 * greater otherwise.
 *
 * This function just shut down the error module set up by
 * eina_list_init(). It is also called by eina_shutdown(). It returns
 * 0 when it is called the same number of times than
 * eina_error_init().
 */
EAPI int
eina_list_shutdown(void)
{
   return eina_error_shutdown();
}

/**
 * @brief Append the given data to the given linked list.
 *
 * @param list The given list.
 * @param data The data to append.
 * @return A list pointer.
 *
 * This function appends @p data to @p list. If @p data is @c NULL, a
 * new list is returned. On success, a new list pointer that should be
 * used in place of the one given to this function is
 * returned. Otherwise, the old pointer is returned.
 *
 * The following example code demonstrates how to ensure that the
 * given data has been successfully appended.
 *
 * @code
 * Eina_List *list = NULL;
 * extern void *my_data;
 *
 * list = eina_list_append(list, my_data);
 * if (eina_error_get())
 *   {
 *     fprintf(stderr, "ERROR: Memory is low. List allocation failed.\n");
 *     exit(-1);
 *   }
 * @endcode
 */
EAPI Eina_List *
eina_list_append(Eina_List *list, const void *data)
{
   Eina_List *l, *new_l;

   eina_error_set(0);
   new_l = _eina_list_mempool_list_new(list);
   if (!new_l) return list;
   new_l->next = NULL;
   new_l->data = (void *)data;
   if (!list)
     {
	new_l->prev = NULL;
	return _eina_list_setup_accounting(new_l);
     }

   l = list->accounting->last;
   list->accounting->last = new_l;

   l->next = new_l;
   new_l->prev = l;

   _eina_list_update_accounting(list, new_l);
   return list;
}

/**
 * @brief Prepends the given data to the given linked list.
 *
 * @param list The given list.
 * @param data The data to prepend.
 * @return A list pointer.
 *
 * This function prepends @p data to @p list. If @p data is @c NULL, a
 * new list is returned. On success, a new list pointer that should be
 * used in place of the one given to this function is
 * returned. Otherwise, the old pointer is returned.
 *
 * The following example code demonstrates how to ensure that the
 * given data has been successfully prepended.
 *
 * Example:
 * @code
 * Eina_List *list = NULL;
 * extern void *my_data;
 *
 * list = eina_list_prepend(list, my_data);
 * if (eina_error_get())
 *   {
 *     fprintf(stderr, "ERROR: Memory is low. List allocation failed.\n");
 *     exit(-1);
 *   }
 * @endcode
 */
EAPI Eina_List *
eina_list_prepend(Eina_List *list, const void *data)
{
   Eina_List *new_l;

   eina_error_set(0);
   new_l = _eina_list_mempool_list_new(list);
   if (!new_l) return list;

   new_l->prev = NULL;
   new_l->next = list;
   new_l->data = (void *)data;

   if (!list) return _eina_list_setup_accounting(new_l);

   list->prev = new_l;

   _eina_list_update_accounting(list, new_l);

   return new_l;
}

/**
 * @brief Insert the given data into the given linked list after the specified data.
 *
 * @param list The given linked list.
 * @param data The data to insert.
 * @param relative The data to insert after.
 * @return A list pointer.
 *
 * This function inserts @p data to @p list after @p relative. If
 * @p relative is not in the list, @p data is appended to the end of
 * the list.  If @p list is @c NULL, a  new list is returned. If there
 * are multiple instances of @p relative in the list, @p data is
 * inserted after the first instance.On success, a new list pointer
 * that should be used in place of the one given to this function is
 * returned. Otherwise, the old pointer is returned.
 *
 * The following example code demonstrates how to ensure that the
 * given data has been successfully inserted.
 *
 * @code
 * Eina_List *list = NULL;
 * extern void *my_data;
 * extern void *relative_member;
 *
 * list = eina_list_append(list, relative_member);
 * if (eina_error_get())
 *   {
 *     fprintf(stderr, "ERROR: Memory is low. List allocation failed.\n");
 *     exit(-1);
 *   }
 * list = eina_list_append_relative(list, my_data, relative_member);
 * if (eina_error_get())
 *   {
 *     fprintf(stderr, "ERROR: Memory is low. List allocation failed.\n");
 *     exit(-1);
 *   }
 * @endcode
 */
EAPI Eina_List *
eina_list_append_relative(Eina_List *list, const void *data, const void *relative)
{
   Eina_List *l;

   for (l = list; l; l = l->next)
     {
	if (l->data == relative)
	  return eina_list_append_relative_list(list, data, l);
     }
   return eina_list_append(list, data);
}

/**
 * @brief Append a list node to a linked list after the specified member
 *
 * @param list The given linked list.
 * @param data The data to insert.
 * @param relative The list node to insert after.
 * @return A list pointer.
 *
 * This function inserts @p data to @p list after the list node
 * @p relative. If @p list or @p relative are @c NULL, @p data is just
 * appended to @p list using eina_list_append(). If @p list is
 * @c NULL, a  new list is returned. If there are multiple instances
 * of @p relative in the list, @p data is inserted after the first
 * instance. On success, a new list pointer that should be used in
 * place of the one given to this function is returned. Otherwise, the
 * old pointer is returned.
 */
EAPI Eina_List *
eina_list_append_relative_list(Eina_List *list, const void *data, Eina_List *relative)
{
   Eina_List *new_l;

   if ((!list) || (!relative)) return eina_list_append(list, data);
   eina_error_set(0);
   new_l = _eina_list_mempool_list_new(list);
   if (!new_l) return list;

   new_l->next = relative->next;
   new_l->data = (void *)data;

   if (relative->next)
     relative->next->prev = new_l;

   relative->next = new_l;
   new_l->prev = relative;

   _eina_list_update_accounting(list, new_l);

   if (!new_l->next)
     new_l->accounting->last = new_l;

   return list;
}

/**
 * @brief Prepend a data pointer to a linked list before the specified member
 *
 * @param list The given linked list.
 * @param data The data to insert.
 * @param relative The data to insert before.
 * @return A list pointer.
 *
 * This function inserts @p data to @p list before @p relative. If
 * @p relative is not in the list, @p data is prepended to the list
 * with eina_list_prepend(). If @p list is @c NULL, a  new list is
 * returned. If there are multiple instances of @p relative in the
 * list, @p data is inserted before the first instance. On success, a
 * new list pointer that should be used in place of the one given to
 * this function is returned. Otherwise, the old pointer is returned.
 *
 * The following code example demonstrates how to ensure that the
 * given data has been successfully inserted.
 *
 * @code
 * Eina_List *list = NULL;
 * extern void *my_data;
 * extern void *relative_member;
 *
 * list = eina_list_append(list, relative_member);
 * if (eina_error_get_error())
 *   {
 *     fprintf(stderr, "ERROR: Memory is low. List allocation failed.\n");
 *     exit(-1);
 *   }
 * list = eina_list_prepend_relative(list, my_data, relative_member);
 * if (eina_error_get())
 *   {
 *     fprintf(stderr, "ERROR: Memory is low. List allocation failed.\n");
 *     exit(-1);
 *   }
 * @endcode
 */
EAPI Eina_List *
eina_list_prepend_relative(Eina_List *list, const void *data, const void *relative)
{
   Eina_List *l;

   for (l = list; l; l = l->next)
     {
	if (l->data == relative)
	  return eina_list_prepend_relative_list(list, data, l);
     }
   return eina_list_prepend(list, data);
}

/**
 * @brief Prepend a list node to a linked list before the specified member
 *
 * @param list The given linked list.
 * @param data The data to insert.
 * @param relative The list node to insert before.
 * @return A list pointer.
 *
 * This function inserts @p data to @p list before the list node
 * @p relative. If @p list or @p relative are @c NULL, @p data is just
 * prepended to @p list using eina_list_prepend(). If @p list is
 * @c NULL, a  new list is returned. If there are multiple instances
 * of @p relative in the list, @p data is inserted before the first
 * instance. On success, a new list pointer that should be used in
 * place of the one given to this function is returned. Otherwise, the
 * old pointer is returned.
 */
EAPI Eina_List *
eina_list_prepend_relative_list(Eina_List *list, const void *data, Eina_List *relative)
{
   Eina_List *new_l;

   if ((!list) || (!relative)) return eina_list_prepend(list, data);
   eina_error_set(0);
   new_l = _eina_list_mempool_list_new(list);
   if (!new_l) return list;

   new_l->prev = relative->prev;
   new_l->next = relative;
   new_l->data = (void *)data;

   if (relative->prev) relative->prev->next = new_l;
   relative->prev = new_l;

   _eina_list_update_accounting(list, new_l);

   if (new_l->prev)
     return list;

   return new_l;
}

/**
 * @brief Remove the first instance of the specified data from the given list.
 *
 * @param list The given list.
 * @param data The specified data.
 * @return A list pointer.
 *
 * This function removes the first instance of @p data from
 * @p list. If the specified data is not in the given list (tihis
 * include the case where @p data is @c NULL), nothing is done. If
 * @p list is @c NULL, @c NULL is returned, otherwise a new list
 * pointer that should be used in place of the one passed to this
 * function.
 */
EAPI Eina_List *
eina_list_remove(Eina_List *list, const void *data)
{
   Eina_List *l;

   for (l = list; l; l = l->next)
     {
	if (l->data == data)
	  return eina_list_remove_list(list, l);
     }
   return list;
}

/**
 * @brief Remove the specified data.
 *
 * @param list The given linked list.
 * @param remove_list The list node which is to be removed.
 * @return A list pointer.
 *
 * This function removes the list node @p remove_list from @p list and
 * frees the list node structure @p remove_list. If @p list is
 * @c NULL, this function returns @c NULL. If @p remove_list is
 * @c NULL, it returns @p list, otherwise, a new list pointer that
 * should be used in place of the one passed to this function.
 *
 * The following code gives an example.
 *
 * @code
 * extern Eina_List *list;
 * Eina_List *l;
 * extern void *my_data;
 *
 * for (l = list; l; l= l->next)
 *   {
 *     if (l->data == my_data)
 *       {
 *         list = eina_list_remove_list(list, l);
 *         break;
 *       }
 *   }
 * @endcode
 */
EAPI Eina_List *
eina_list_remove_list(Eina_List *list, Eina_List *remove_list)
{
   Eina_List *return_l;

   if (!list) return NULL;
   if (!remove_list) return list;
   if (remove_list->next) remove_list->next->prev = remove_list->prev;
   if (remove_list->prev)
     {
	remove_list->prev->next = remove_list->next;
	return_l = list;
     }
   else
     return_l = remove_list->next;
   if (remove_list == list->accounting->last)
     list->accounting->last = remove_list->prev;

   _eina_list_mempool_list_free(remove_list);
   return return_l;
}

/**
 * @brief Free an entire list and all the nodes, ignoring the data contained.

 * @param list The list to free
 * @return A NULL pointer
 *
 * This function frees all the nodes of @p list. It does not free the
 * data of the nodes. To free them, use #EINA_LIST_ITER_NEXT.
 */
EAPI Eina_List *
eina_list_free(Eina_List *list)
{
   Eina_List *l, *free_l;

   if (!list) return NULL;
   for (l = list; l;)
     {
	free_l = l;
	l = l->next;

	_eina_list_mempool_list_free(free_l);
     }
   return NULL;
}

/**
 * @brief Move the specified data to the head of the list.
 *
 * @param list The list handle to move the data.
 * @param move_list The list node to move.
 * @return A new list handle to replace the old one
 *
 * This function move @p move_list to the front of @p list. If list is
 * @c NULL, @c NULL is returned. If @p move_list is @c NULL,
 * @p list is returned. Otherwise, a new list pointer that should be
 * used in place of the one passed to this function.
 *
 * Example:
 * @code
 * extern Eina_List *list;
 * Eina_List *l;
 * extern void *my_data;
 *
 * for (l = list; l; l= l->next)
 *   {
 *     if (l->data == my_data)
 *       {
 *         list = eina_list_promote_list(list, l);
 *         break;
 *       }
 *   }
 * @endcode
 */
EAPI Eina_List *
eina_list_promote_list(Eina_List *list, Eina_List *move_list)
{
   if (!list) return NULL;
   if (!move_list) return list;
   /* Promoting head to be head. */
   if (move_list == list) return list;

   /* Update pointer to the last entry if necessary. */
   if (move_list == list->accounting->last)
     list->accounting->last = move_list->prev;

   /* Remove the promoted item from the list. */
   if (move_list->next) move_list->next->prev = move_list->prev;
   if (move_list->prev) move_list->prev->next = move_list->next;
   else list = move_list->next;

   assert(list);

   move_list->prev = list->prev;
   if (list->prev)
     list->prev->next = move_list;
   list->prev = move_list;
   move_list->next = list;
   return move_list;
}

/**
 * @brief Find a member of a list and return the member.
 *
 * @param list The list to search for a data.
 * @param data The data pointer to find in the list.
 * @return The found member data pointer if foun, @c NULL otherwise.
 *
 * This function searches in @p list from beginning to end for the
 * first member whose data pointer is @p data. If it is found, @p data
 * will be returned, otherwise NULL will be returned.
 *
 * Example:
 * @code
 * extern Eina_List *list;
 * extern void *my_data;
 *
 * if (eina_list_find(list, my_data) == my_data)
 *   {
 *     printf("Found member %p\n", my_data);
 *   }
 * @endcode
 */
EAPI void *
eina_list_find(const Eina_List *list, const void *data)
{
   if (eina_list_find_list(list, data)) return (void*) data;
   return NULL;
}

/**
 * @brief Find a member of a list and return the list node containing that member.
 *
 * @param list The list to search for data.
 * @param data The data pointer to find in the list.
 * @return The found members list node on success, @c NULL otherwise.
 *
 * This function searches in @p list from beginning to end for the
 * first member whose data pointer is @p data. If it is found, the
 * list node containing the specified member is returned, otherwise
 * @c NULL is returned.
 */
EAPI Eina_List *
eina_list_find_list(const Eina_List *list, const void *data)
{
   const Eina_List *l;

   for (l = list; l; l = l->next)
     {
	if (l->data == data) return (Eina_List *)l;
     }
   return NULL;
}

/**
 * @brief Get the nth member's data pointer in a list.
 *
 * @param list The list to get the specified member number from.
 * @param n The number of the element (0 being the first).
 * @return The data pointer stored in the specified element.
 *
 * This function returns the data pointer of element number @p n, in
 * the @p list. The first element in the array is element number 0. If
 * the element number @p n does not exist, @c NULL is
 * returned. Otherwise, the data of the found element is returned.
 */
EAPI void *
eina_list_nth(const Eina_List *list, unsigned int n)
{
   Eina_List *l;

   l = eina_list_nth_list(list, n);
   return l ? l->data : NULL;
}

/**
 * @brief Get the nth member's list node in a list.
 *
 * @param list The list to get the specfied member number from.
 * @param n The number of the element (0 being the first).
 * @return The list node stored in the numbered element.
 *
 * This function returns the list node of element number @p n, in
 * @ list. The first element in the array is element number 0. If the
 * element number @p n does not exist or @p list is @c NULL or @p n is
 * greater than the count of elements in @p list minus 1, @c NULL is
 * returned. Otherwise the list node stored in the numbered element is
 * returned.
 */
EAPI Eina_List *
eina_list_nth_list(const Eina_List *list, unsigned int n)
{
   const Eina_List *l;
   unsigned int i;

   /* check for non-existing nodes */
   if ((!list) || (n > (list->accounting->count - 1)))
     return NULL;

   /* if the node is in the 2nd half of the list, search from the end
    * else, search from the beginning.
    */
   if (n > (list->accounting->count / 2))
     {
	for (i = list->accounting->count - 1,
	     l = list->accounting->last;
	     l;
	     l = l->prev, i--)
	  {
	     if (i == n) return (Eina_List *)l;
	  }
     }
   else
     {
	for (i = 0, l = list; l; l = l->next, i++)
	  {
	     if (i == n) return (Eina_List *)l;
	  }
     }
   abort();
}

/**
 * @brief Get the last list node in the list.
 *
 * @param list The list to get the last list node from.
 * @return The last list node in the list.
 *
 * This function returns the last list node in the list. If @p list is
 * @c NULL or empty, @c NULL is returned.
 *
 * This is a order-1 operation (it takes the same short time
 * regardless of the length of the list).
 */
static inline Eina_List *eina_list_last(const Eina_List *list);

/**
 * @brief Get the next list node after the specified list node.
 *
 * @param list The list node to get the next list node from
 * @return The next list node on success, @c NULL otherwise.
 *
 * This function returns the next list node after the current one in
 * @p list. It is equivalent to list->next. If @p list is @c NULL or
 * if no next list node exists, it returns @c NULL.
 */
static inline Eina_List *eina_list_next(const Eina_List *list);

/**
 * @brief Get the previous list node before the specified list node.
 *
 * @param list The list node to get the previous list node from.
 * @return The previous list node o success, @c NULL otherwise.
 * if no previous list node exists
 *
 * This function returns the previous list node before the current one
 * in @p list. It is equivalent to list->prev. If @p list is @c NULL or
 * if no previous list node exists, it returns @c NULL.
 */
static inline Eina_List *eina_list_prev(const Eina_List *list);

/**
 * @brief Get the list node data member.
 *
 * @param list The list node to get the data member of.
 * @return The data member from the list node.
 *
 * This function returns the data member of the specified list node @p
 * list. It is equivalent to list->data. If @p list is @c NULL, this
 * function returns @c NULL.
 */
static inline void *eina_list_data(const Eina_List *list);

/**
 * @brief Get the count of the number of items in a list.
 *
 * @param list The list whose count to return.
 * @return The number of members in the list.
 *
 * This function returns how many members @p list contains. If the
 * list is @c NULL, 0 is returned.
 *
 * NB: This is an order-1 operation and takes the same tiem regardless
 * of the length of the list.
 */
static inline unsigned int eina_list_count(const Eina_List *list);

/**
 * @brief Reverse all the elements in the list.
 *
 * @param list The list to reverse.
 * @return The list after it has been reversed.
 *
 * This function reverses the order of all elements in @p list, so the
 * last member is now first, and so on. If @p list is @c NULL, this
 * functon returns @c NULL.
 */
EAPI Eina_List *
eina_list_reverse(Eina_List *list)
{
   Eina_List *l1, *l2;

   if (!list) return NULL;
   l1 = list;
   l2 = list->accounting->last;
   while (l1 != l2)
     {
	void *data;

	data = l1->data;
	l1->data = l2->data;
	l2->data = data;
	l1 = l1->next;
	if (l1 == l2) break;
	l2 = l2->prev;
     }

   return list;
}

/**
 * @brief Sort a list according to the ordering func will return.
 *
 * @param list The list handle to sort.
 * @param size The length of the list to sort.
 * @param func A function pointer that can handle comparing the list data
 * nodes.
 * @return A new sorted list.
 *
 * This function sorts @p list. @p size if the number of the first
 * element to sort. If @p size is 0 or greater than the number of
 * elements in @p list, all the elemnts are sorted. @p func is used to
 * compare two elements of @p list. If @p list or @p func are @c NULL,
 * this function returns @c NULL.
 *
 * Example:
 * @code
 * int
 * sort_cb(void *d1, void *d2)
 * {
 *   const char *txt = NULL;
 *    const char *txt2 = NULL;
 *
 *    if(!d1) return(1);
 *    if(!d2) return(-1);
 *
 *    return(strcmp((const char*)d1, (const char*)d2));
 * }
 * extern Eina_List *list;
 *
 * list = eina_list_sort(list, eina_list_count(list), sort_cb);
 * if (eina_error_get())
 *   {
 *     fprintf(stderr, "ERROR: Memory is low. List Sorting failed.\n");
 *     exit(-1);
 *   }
 * @endcode
 */
EAPI Eina_List *
eina_list_sort(Eina_List *list, unsigned int size, Eina_Compare_Cb func)
{
   Eina_List*   last;
   unsigned int	list_number;
   unsigned int	middle;
   unsigned int	list_size;

   if (!list || !func) return NULL;

   /* if the caller specified an invalid size, sort the whole list */
   if ((size == 0) ||
       (size > list->accounting->count))
     size = list->accounting->count;

   last = list->accounting->last;
   middle = size - size / 2;

   for (list_number = middle, list_size = 1;
	list_size < middle * 2;
	list_number >>= 1, list_size <<= 1)
     {
	Eina_List	*head1 = list;
	unsigned int	limit = size;
	unsigned int	process_list;
	unsigned int	pass_number;
	unsigned int	split_size = list_size;

	for (process_list = 0; process_list < list_number + 1; ++process_list)
	  {
	     Eina_List		*head2;
	     unsigned int	size_sum;
	     int		size1, size2;
	     int		i;

	     size1 = limit < split_size ? limit : split_size;
	     limit -= size1;

	     size2 = limit < split_size ? limit : split_size;
	     limit -= size2;

	     size_sum = size1 + size2;

	     for (head2 = head1, i = 0; i < size1; ++i)
	       head2 = eina_list_next (head2);

	     for (pass_number = 0; pass_number < size_sum; ++pass_number)
	       {
		  Eina_List	*next;
		  Eina_List	*prev1;
		  Eina_List	*prev2;

		  if (size1 == 0 || head1 == NULL) /* List1 is empty, head1 is already at the end of the list. So only need to update head2 */
		    {
		       for (; pass_number < size_sum; ++pass_number)
			 head2 = eina_list_next (head2);
		       break;
		    }
		  else
		    if (size2 == 0 || head2 == NULL) /* List2 is empty, just leave */
		      break;
		    else
		      if (func (head1->data, head2->data) < 0)
			{
			   head1 = eina_list_next (head1);
			   --size1;
			}
		      else
			{
			   next = eina_list_next (head2);
			   prev1 = eina_list_prev (head1);
			   prev2 = eina_list_prev (head2);

			   if (next)
			     next->prev = prev2;
			   if (prev1)
			     prev1->next = head2;
			   if (prev2)
			     prev2->next = next;

			   head2->prev = prev1;
			   head2->next = head1;
			   head1->prev = head2;

			   --size2;

                           if (head1 == list)
                             list = head2;
                           if (head2 == last)
                             last = prev2;

			   head2 = next;
			}
	       }
	     head1 = head2;
	  }
     }

   list->accounting->last = last;
   return list;
}

/**
 * @brief Returned a new iterator asociated to a list.
 *
 * @param list The list.
 * @return A new iterator.
 *
 * This function returns a newly allocated iterator associated to
 * @p list. If @p list is @c NULL or the count member of @p list is
 * less or equal than 0, this function returns NULL. If the memory can
 * not be allocated, NULL is returned and #EINA_ERROR_OUT_OF_MEMORY is
 * set. Otherwise, a valid iterator is returned.
 */
EAPI Eina_Iterator *
eina_list_iterator_new(const Eina_List *list)
{
   Eina_Iterator_List *it;

   if (!list) return NULL;

   eina_error_set(0);
   it = calloc(1, sizeof (Eina_Iterator_List));
   if (!it) {
      eina_error_set(EINA_ERROR_OUT_OF_MEMORY);
      return NULL;
   }

   it->head = list;
   it->current = list;

   it->iterator.next = FUNC_ITERATOR_NEXT(eina_list_iterator_next);
   it->iterator.get_container = FUNC_ITERATOR_GET_CONTAINER(eina_list_iterator_get_container);
   it->iterator.free = FUNC_ITERATOR_FREE(eina_list_iterator_free);

   return &it->iterator;
}

/**
 * @brief Returned a new accessor asociated to a list.
 *
 * @param list The list.
 * @return A new accessor.
 *
 * This function returns a newly allocated accessor associated to
 * @p list. If @p list is @c NULL or the count member of @p list is
 * less or equal than 0, this function returns NULL. If the memory can
 * not be allocated, NULL is returned and #EINA_ERROR_OUT_OF_MEMORY is
 * set. Otherwise, a valid accessor is returned.
 */
EAPI Eina_Accessor *
eina_list_accessor_new(const Eina_List *list)
{
   Eina_Accessor_List *it;

   if (!list) return NULL;

   eina_error_set(0);
   it = calloc(1, sizeof (Eina_Accessor_List));
   if (!it) {
      eina_error_set(EINA_ERROR_OUT_OF_MEMORY);
      return NULL;
   }

   it->head = list;
   it->current = list;
   it->index = 0;

   it->accessor.get_at = FUNC_ACCESSOR_GET_AT(eina_list_accessor_get_at);
   it->accessor.get_container = FUNC_ACCESSOR_GET_CONTAINER(eina_list_accessor_get_container);
   it->accessor.free = FUNC_ACCESSOR_FREE(eina_list_accessor_free);

   return &it->accessor;
}

/**
 * @}
 */