#ifdef HAVE_CONFIG_H
# include <config.h>
#endif

#include <stdlib.h>
#include <string.h>

#include "Ecore_Data.h"

/* Some tests showed that beyond that value heap sort is faster than merge sort
 * (in this implementation). This value has to be changed or at least review
 * if someone is changing the implementation. */
#define ECORE_MERGESORT_LIMIT 40000

/* Return information about the list */
static void *           _ecore_list_current(Ecore_List *list);

/* Adding functions */
static int              _ecore_list_insert(Ecore_List *list,
                                           Ecore_List_Node *node);
static int              _ecore_list_append_0(Ecore_List *list,
                                             Ecore_List_Node *node);
static int              _ecore_list_prepend_0(Ecore_List *list,
                                              Ecore_List_Node *node);

/* Remove functions */
static void *           _ecore_list_remove_0(Ecore_List *list);
static void *           _ecore_list_first_remove(Ecore_List *list);
static void *           _ecore_list_last_remove(Ecore_List *list);

/* Basic traversal functions */
static void *           _ecore_list_next(Ecore_List *list);
static void *           _ecore_list_last_goto(Ecore_List *list);
static void *           _ecore_list_first_goto(Ecore_List *list);
static void *           _ecore_list_goto(Ecore_List *list, const void *data);
static void *           _ecore_list_index_goto(Ecore_List *list, int idx);

/* Iterative functions */
static int              _ecore_list_for_each(Ecore_List *list,
                                             Ecore_For_Each function,
                                             void *user_data);
static void *           _ecore_list_find(Ecore_List *list,
                                         Ecore_Compare_Cb function,
                                         const void *user_data);

/* Sorting functions */
static Ecore_List_Node *_ecore_list_node_mergesort(Ecore_List_Node *first,
                                                   int n,
                                                   Ecore_Compare_Cb compare,
                                                   int order);
static Ecore_List_Node *_ecore_list_node_merge(Ecore_List_Node *first,
                                               Ecore_List_Node *second,
                                               Ecore_Compare_Cb compare,
                                               int order);
static Ecore_List_Node *_ecore_dlist_node_mergesort(Ecore_List_Node *first,
                                                    int n,
                                                    Ecore_Compare_Cb compare,
                                                    int order);
static Ecore_List_Node *_ecore_dlist_node_merge(Ecore_List_Node *first,
                                                Ecore_List_Node *second,
                                                Ecore_Compare_Cb compare,
                                                int order);

/* Private double linked list functions */
static void *_ecore_dlist_previous(Ecore_DList *list);
static void *_ecore_dlist_first_remove(Ecore_DList *list);
static void *_ecore_dlist_index_goto(Ecore_DList *list, int idx);

/**
   @defgroup Ecore_Data_List_Creation_Group List Creation/Destruction Functions

   Functions that create, initialize and destroy Ecore_Lists.
 */

/**
 * Create and initialize a new list.
 * @return  A new initialized list on success, @c NULL on failure.
 * @ingroup Ecore_Data_List_Creation_Group
 */
EAPI Ecore_List *
ecore_list_new(void)
{
   Ecore_List *list;

   list = (Ecore_List *)malloc(sizeof(Ecore_List));
   if (!list)
      return NULL;

   if (!ecore_list_init(list))
     {
        FREE(list);
        return NULL;
     }

   return list;
}

/**
 * Initialize a list to some sane starting values.
 * @param   list The list to initialize.
 * @return  @c TRUE if successful, @c FALSE if an error occurs.
 * @ingroup Ecore_Data_List_Creation_Group
 */
EAPI int
ecore_list_init(Ecore_List *list)
{
   CHECK_PARAM_POINTER_RETURN("list", list, FALSE);

   memset(list, 0, sizeof(Ecore_List));

   return TRUE;
}

/**
 * Free a list and all of it's nodes.
 * @param   list The list to be freed.
 * @ingroup Ecore_Data_List_Creation_Group
 */
EAPI void
ecore_list_destroy(Ecore_List *list)
{
   void *data;

   CHECK_PARAM_POINTER("list", list);

   while (list->first)
     {
        data = _ecore_list_first_remove(list);
        if (list->free_func)
           list->free_func(data);
     }

   FREE(list);
}

/**
 * Set the function for freeing data.
 * @param  list      The list that will use this function when nodes are
 *                   destroyed.
 * @param  free_func The function that will free the key data.
 * @return @c TRUE on successful set, @c FALSE otherwise.
 */
EAPI int
ecore_list_free_cb_set(Ecore_List *list, Ecore_Free_Cb free_func)
{
   CHECK_PARAM_POINTER_RETURN("list", list, FALSE);

   list->free_func = free_func;

   return TRUE;
}

/**
 * Checks the list for any nodes.
 * @param  list  The list to check for nodes
 * @return @c TRUE if no nodes in list, @c FALSE if the list contains nodes
 */
EAPI int
ecore_list_empty_is(Ecore_List *list)
{
   int ret = TRUE;

   CHECK_PARAM_POINTER_RETURN("list", list, TRUE);

   if (list->nodes)
      ret = FALSE;

   return ret;
}

/**
 * Returns the number of the current node.
 * @param  list The list to return the number of the current node.
 * @return The number of the current node in the list.
 */
EAPI int
ecore_list_index(Ecore_List *list)
{
   int ret;

   CHECK_PARAM_POINTER_RETURN("list", list, FALSE);

   ret = list->index;

   return ret;
}

/**
 * Find the number of nodes in the list.
 * @param  list The list to find the number of nodes
 * @return The number of nodes in the list.
 */
EAPI int
ecore_list_count(Ecore_List *list)
{
   int ret = 0;

   CHECK_PARAM_POINTER_RETURN("list", list, FALSE);

   ret = list->nodes;

   return ret;
}

/**
   @defgroup Ecore_Data_List_Add_Item_Group List Item Adding Functions

   Functions that are used to add nodes to an Ecore_List.
 */

/**
 * Append data to the list.
 * @param   list The list.
 * @param   data The data to append.
 * @return  @c FALSE if an error occurs, @c TRUE if appended successfully
 * @ingroup Ecore_Data_List_Add_Item_Group
 */
EAPI inline int
ecore_list_append(Ecore_List *list, void *data)
{
   int ret;
   Ecore_List_Node *node;

   CHECK_PARAM_POINTER_RETURN("list", list, FALSE);

   node = ecore_list_node_new();
   node->data = data;

   ret = _ecore_list_append_0(list, node);

   return ret;
}

/* For adding items to the end of the list */
static int
_ecore_list_append_0(Ecore_List *list, Ecore_List_Node *end)
{
   if (list->last)
      list->last->next = end;

   list->last = end;

   if (!list->first)
     {
        list->first = end;
        list->index = 0;
        list->current = NULL;
     }

   if (list->index >= list->nodes)
      list->index++;

   list->nodes++;

   return TRUE;
}

/**
 * Prepend data to the beginning of the list.
 * @param  list The list.
 * @param  data The data to prepend.
 * @return @c FALSE if an error occurs, @c TRUE if prepended successfully.
 * @ingroup Ecore_Data_List_Add_Item_Group
 */
EAPI inline int
ecore_list_prepend(Ecore_List *list, void *data)
{
   int ret;
   Ecore_List_Node *node;

   CHECK_PARAM_POINTER_RETURN("list", list, FALSE);

   node = ecore_list_node_new();
   node->data = data;

   ret = _ecore_list_prepend_0(list, node);

   return ret;
}

/* For adding items to the beginning of the list */
static int
_ecore_list_prepend_0(Ecore_List *list, Ecore_List_Node *start)
{
   /* Put it at the beginning of the list */
   start->next = list->first;

   list->first = start;

   /* If no last node, then the first node is the last node */
   if (!list->last)
      list->last = list->first;

   list->nodes++;
   list->index++;

   return TRUE;
}

/**
 * Insert data in front of the current point in the list.
 * @param   list The list to hold the inserted @p data.
 * @param   data The data to insert into @p list.
 * @return  @c FALSE if there is an error, @c TRUE on success
 * @ingroup Ecore_Data_List_Add_Item_Group
 */
EAPI inline int
ecore_list_insert(Ecore_List *list, void *data)
{
   int ret;
   Ecore_List_Node *node;

   CHECK_PARAM_POINTER_RETURN("list", list, FALSE);

   node = ecore_list_node_new();
   node->data = data;

   ret = _ecore_list_insert(list, node);

   return ret;
}

/* For adding items in front of the current position in the list */
static int
_ecore_list_insert(Ecore_List *list, Ecore_List_Node *new_node)
{
   /*
    * If the current point is at the beginning of the list, then it's the
    * same as prepending it to the list.
    */
   if (list->current == list->first)
      return _ecore_list_prepend_0(list, new_node);

   if (!list->current)
     {
        int ret_value;

        ret_value = _ecore_list_append_0(list, new_node);
        list->current = list->last;

        return ret_value;
     }

   /* Setup the fields of the new node */
   new_node->next = list->current;

   /* And hook the node into the list */
   _ecore_list_index_goto(list, ecore_list_index(list) - 1);

   list->current->next = new_node;

   /* Now move the current item to the inserted item */
   list->current = new_node;
   list->nodes++;

   return TRUE;
}
/**
 * Append a list to the list.
 * @param   list The list.
 * @param   append The list to append.
 * @return  @c FALSE if an error occurs, @c TRUE if appended successfully
 * @ingroup Ecore_Data_List_Add_Item_Group
 */

EAPI int
ecore_list_append_list(Ecore_List *list, Ecore_List *append)
{
   CHECK_PARAM_POINTER_RETURN("list",   list,   FALSE);
   CHECK_PARAM_POINTER_RETURN("append", append, FALSE);

   if (ecore_list_empty_is(append))
      return TRUE;

   if (ecore_list_empty_is(list))
     {
        list->first = append->first;
        list->current = list->first;
        list->last = append->last;
        list->nodes = append->nodes;
     }
   else
     {
        list->last->next = append->first;
        list->last = append->last;
        list->nodes += append->nodes;
     }

   ecore_list_init(append);
   return TRUE;
}

/**
 * Prepend a list to the beginning of the list.
 * @param  list The list.
 * @param  prepend The list to prepend.
 * @return @c FALSE if an error occurs, @c TRUE if prepended successfully.
 * @ingroup Ecore_Data_List_Add_Item_Group
 */
EAPI int
ecore_list_prepend_list(Ecore_List *list, Ecore_List *prepend)
{
   CHECK_PARAM_POINTER_RETURN("list",    list,    FALSE);
   CHECK_PARAM_POINTER_RETURN("prepend", prepend, FALSE);

   if (ecore_list_empty_is(prepend))
      return TRUE;

   if (ecore_list_empty_is(list))
     {
        list->first = prepend->first;
        list->current = NULL;
        list->last = prepend->last;
        list->nodes = prepend->nodes;
     }
   else
     {
        prepend->last->next = list->first;
        list->first = prepend->first;
        list->nodes += prepend->nodes;
        list->index += prepend->nodes;
     }

   ecore_list_init(prepend);
   return TRUE;
}

/**
   @defgroup Ecore_Data_List_Remove_Item_Group List Item Removing Functions

   Functions that remove nodes from an Ecore_List.
 */

/**
 * Remove the current item from the list.
 * @param   list The list to remove the current item
 * @return  A pointer to the removed data on success, @c NULL on failure.
 * @ingroup Ecore_Data_List_Remove_Item_Group
 */
EAPI inline void *
ecore_list_remove(Ecore_List *list)
{
   void *ret;

   CHECK_PARAM_POINTER_RETURN("list", list, NULL);

   ret = _ecore_list_remove_0(list);

   return ret;
}

/* Remove the current item from the list */
static void *
_ecore_list_remove_0(Ecore_List *list)
{
   void *ret = NULL;
   Ecore_List_Node *old;

   if (!list)
      return NULL;

   if (ecore_list_empty_is(list))
      return NULL;

   if (!list->current)
      return NULL;

   if (list->current == list->first)
      return _ecore_list_first_remove(list);

   if (list->current == list->last)
      return _ecore_list_last_remove(list);

   old = list->current;

   _ecore_list_index_goto(list, list->index - 1);

   list->current->next = old->next;
   old->next = NULL;
   ret = old->data;
   old->data = NULL;

   _ecore_list_next(list);

   ecore_list_node_destroy(old, NULL);
   list->nodes--;

   return ret;
}

/**
 * Remove and free the data in lists current position.
 * @param   list The list to remove and free the current item.
 * @return  @c TRUE on success, @c FALSE on error
 * @ingroup Ecore_Data_List_Remove_Item_Group
 */
EAPI int
ecore_list_remove_destroy(Ecore_List *list)
{
   void *data;

   CHECK_PARAM_POINTER_RETURN("list", list, FALSE);

   data = _ecore_list_remove_0(list);
   if (list->free_func)
      list->free_func(data);

   return TRUE;
}

/**
 * Remove the first item from the list.
 * @param   list The list to remove the current item
 * @return  Returns a pointer to the removed data on success, @c NULL on
 *          failure.
 * @ingroup Ecore_Data_List_Remove_Item_Group
 */
EAPI inline void *
ecore_list_first_remove(Ecore_List *list)
{
   void *ret;

   CHECK_PARAM_POINTER_RETURN("list", list, NULL);

   ret = _ecore_list_first_remove(list);

   return ret;
}

/* Remove the first item from the list */
static void *
_ecore_list_first_remove(Ecore_List *list)
{
   void *ret = NULL;
   Ecore_List_Node *old;

   if (!list)
      return NULL;

   if (ecore_list_empty_is(list))
      return NULL;

   old = list->first;

   list->first = list->first->next;

   if (list->current == old)
      list->current = list->first;
   else
      (list->index ? list->index-- : 0);

   if (list->last == old)
      list->last = list->first;

   ret = old->data;
   old->data = NULL;

   ecore_list_node_destroy(old, NULL);
   list->nodes--;

   return ret;
}

/**
 * Remove the last item from the list.
 * @param   list The list to remove the last node from
 * @return  A pointer to the removed data on success, @c NULL on failure.
 * @ingroup Ecore_Data_List_Remove_Item_Group
 */
EAPI inline void *
ecore_list_last_remove(Ecore_List *list)
{
   void *ret;

   CHECK_PARAM_POINTER_RETURN("list", list, NULL);

   ret = _ecore_list_last_remove(list);

   return ret;
}

/* Remove the last item from the list */
static void *
_ecore_list_last_remove(Ecore_List *list)
{
   void *ret = NULL;
   Ecore_List_Node *old, *prev;

   if (!list)
      return NULL;

   if (ecore_list_empty_is(list))
      return NULL;

   old = list->last;
   if (list->current == old)
      list->current = NULL;

   if (list->first == old)
      list->first = NULL;

   for (prev = list->first; prev && prev->next != old; prev = prev->next) ;
   list->last = prev;
   if (prev)
      prev->next = NULL;

   old->next = NULL;
   ret = old->data;
   old->data = NULL;

   ecore_list_node_destroy(old, NULL);
   list->nodes--;

   return ret;
}

/**
   @defgroup Ecore_Data_List_Traverse_Group List Traversal Functions

   Functions that can be used to traverse an Ecore_List.
 */

/**
 * Make the current item the item with the given index number.
 * @param   list  The list.
 * @param   idx The position to move the current item.
 * @return  A pointer to new current item on success, @c NULL on failure.
 * @ingroup Ecore_Data_List_Traverse_Group
 */
EAPI inline void *
ecore_list_index_goto(Ecore_List *list, int idx)
{
   void *ret;

   CHECK_PARAM_POINTER_RETURN("list", list, NULL);

   ret = _ecore_list_index_goto(list, idx);

   return ret;
}

/* This is the non-threadsafe version, use this inside internal functions that
 * already lock the list */
static void *
_ecore_list_index_goto(Ecore_List *list, int idx)
{
   int i;

   if (!list)
      return NULL;

   if (ecore_list_empty_is(list))
      return NULL;

   if (idx > ecore_list_count(list) || idx < 0)
      return NULL;

   if (idx < list->index)
     {
        _ecore_list_first_goto(list);
        i = 0;
     }
   else
      i = list->index;

   for (; i < idx && _ecore_list_next(list); i++) ;

   if (i >= list->nodes)
      return NULL;

   list->index = i;

   return list->current->data;
}

/**
 * Make the current item the node that contains @p data.
 * @param   list The list.
 * @param   data The data to find.
 * @return  A pointer to @p data on success, @c NULL on failure.
 * @ingroup Ecore_Data_List_Traverse_Group
 */
EAPI inline void *
ecore_list_goto(Ecore_List *list, const void *data)
{
   void *ret;

      CHECK_PARAM_POINTER_RETURN("list", list, NULL);

   ret = _ecore_list_goto(list, data);

   return ret;
}

/* Set the current position to the node containing data */
static void *
_ecore_list_goto(Ecore_List *list, const void *data)
{
   int idx;
   Ecore_List_Node *node;

   if (!list)
      return NULL;

   idx = 0;

   node = list->first;
   while (node && node->data)
     {
        Ecore_List_Node *next;

        if (node->data == data)
           break;

        next = node->next;

        node = next;

        idx++;
     }

   if (!node)
      return NULL;

   list->current = node;
   list->index = idx;

   return list->current->data;
}

/**
 * Make the current item the first item in the list
 * @param   list The list.
 * @return  A pointer to the first item on success, @c NULL on failure
 * @ingroup Ecore_Data_List_Traverse_Group
 */
EAPI inline void *
ecore_list_first_goto(Ecore_List *list)
{
   void *ret;

      CHECK_PARAM_POINTER_RETURN("list", list, NULL);

   ret = _ecore_list_first_goto(list);

   return ret;
}

/* Set the current position to the start of the list */
static void *
_ecore_list_first_goto(Ecore_List *list)
{
   if (!list || !list->first)
      return NULL;

   list->current = list->first;
   list->index = 0;

   return list->current->data;
}

/**
 * Make the current item the last item in the list.
 * @param   list The list.
 * @return  A pointer to the last item on success, @c NULL on failure.
 * @ingroup Ecore_Data_List_Traverse_Group
 */
EAPI inline void *
ecore_list_last_goto(Ecore_List *list)
{
   void *ret;

      CHECK_PARAM_POINTER_RETURN("list", list, NULL);

   ret = _ecore_list_last_goto(list);

   return ret;
}

/* Set the current position to the end of the list */
static void *
_ecore_list_last_goto(Ecore_List *list)
{
   if (!list || !list->last)
      return NULL;

   list->current = list->last;
   list->index = (list->nodes - 1);

   return list->current->data;
}

/**
 * Retrieve the data pointed to by the current item in @p list.
 * @param  list The list.
 * @return Returns the data at current position, can be @c NULL.
 */
EAPI inline void *
ecore_list_current(Ecore_List *list)
{
   void *ret;

   ret = _ecore_list_current(list);

   return ret;
}

/**
 * Retrieve the data pointed to by the first item in @p list.
 * @param  list The list.
 * @return Returns the data at current position, can be @c NULL.
 */
EAPI inline void *
ecore_list_first(Ecore_List *list)
{
   void *ret;

   if (!list->first)
      return NULL;

   ret = list->first->data;

   return ret;
}

/**
 * Retrieve the data pointed to by the last item in @p list.
 * @param  list The list.
 * @return Returns the data at current position, can be @c NULL.
 */
EAPI inline void *
ecore_list_last(Ecore_List *list)
{
   void *ret;

   if (!list->last)
      return NULL;

   ret = list->last->data;

   return ret;
}

/* Return the data of the current node without incrementing */
static void *
_ecore_list_current(Ecore_List *list)
{
   void *ret;

   if (!list->current)
      return NULL;

   ret = list->current->data;

   return ret;
}

/**
 * Retrieve the data pointed to by the current item, and make the next item
 * the current item.
 * @param   list The list to retrieve data from.
 * @return  The current item in the list on success, @c NULL on failure.
 */
EAPI inline void *
ecore_list_next(Ecore_List *list)
{
   void *data;

      CHECK_PARAM_POINTER_RETURN("list", list, NULL);

   data = _ecore_list_next(list);

   return data;
}

/* Return the data contained in the current node and go to the next node */
static void *
_ecore_list_next(Ecore_List *list)
{
   void *data;
   Ecore_List_Node *ret;
   Ecore_List_Node *next;

   if (!list->current)
      return NULL;

   ret = list->current;
   next = list->current->next;

   list->current = next;
   list->index++;

   data = ret->data;

   return data;
}

/**
 * Remove all nodes from @p list.
 * @param  list The list.
 * @return Returns @c TRUE on success, @c FALSE on error.
 * @note The data for each item on the list is not freed by
 *       @c ecore_list_clear().
 */
EAPI int
ecore_list_clear(Ecore_List *list)
{
      CHECK_PARAM_POINTER_RETURN("list", list, FALSE);

   while (!ecore_list_empty_is(list))
      _ecore_list_first_remove(list);

   return TRUE;
}

/**
 * Execute function for each node in @p list.
 * @param   list     The list.
 * @param   function The function to pass each node from @p list to.
 * @return  Returns @c TRUE on success, @c FALSE on failure.
 * @ingroup Ecore_Data_List_Traverse_Group
 */
EAPI int
ecore_list_for_each(Ecore_List *list, Ecore_For_Each function, void *user_data)
{
   int ret;

   CHECK_PARAM_POINTER_RETURN("list", list, FALSE);

   ret = _ecore_list_for_each(list, function, user_data);

   return ret;
}

/* The real meat of executing the function for each data node */
static int
_ecore_list_for_each(Ecore_List *list, Ecore_For_Each function, void *user_data)
{
   void *value;

   if (!list || !function)
      return FALSE;

   _ecore_list_first_goto(list);
   while ((value = _ecore_list_next(list)))
      function(value, user_data);

   return TRUE;
}

/**
 * Find data in @p list using the compare function @p func
 * @param list      The list.
 * @param function  The function to test each node of @p list with
 * @param user_data Data to match against (used by @p function)
 * @return the first matching data node, or NULL if none match
 */
EAPI void *
ecore_list_find(Ecore_List *list,
                Ecore_Compare_Cb function,
                const void *user_data)
{
   CHECK_PARAM_POINTER_RETURN("list", list, NULL);

   return _ecore_list_find(list, function, user_data);
}

/* The real meat of finding a node via a compare cb */
static void *
_ecore_list_find(Ecore_List *list,
                 Ecore_Compare_Cb function,
                 const void *user_data)
{
   void *value;
   if (!list || !function)
      return NULL;

   _ecore_list_first_goto(list);
   while ((value = _ecore_list_current(list)))
     {
        if (!function(value, user_data))
           return value;

        ecore_list_next(list);
     }

   return NULL;
}

/**
 * Sort data in @p list using the compare function @p compare
 * @param list      The list.
 * @param compare   The function to compare the data of @p list
 * @param order     The sort direction, possible values are ECORE_SORT_MIN and
 *                  ECORE_SORT_MAX
 * @return          true on success
 *
 * This is a wrapper function for mergesort and heapsort. It
 * tries to choose the fastest algorithm depending on the
 * number of notes. Note: The sort may be unstable.
 */
EAPI int
ecore_list_sort(Ecore_List *list, Ecore_Compare_Cb compare, char order)
{
   CHECK_PARAM_POINTER_RETURN("list", list, 0);

   if (list->nodes < 2)
      return 1;

   if (list->nodes < ECORE_MERGESORT_LIMIT)
      return ecore_list_mergesort(list, compare, order);

   if (!ecore_list_heapsort(list, compare, order))
      return ecore_list_mergesort(list, compare, order);

   return 1;
}

/**
 * Sort data in @p list using the compare function @p compare
 * @param list      The list.
 * @param compare   The function to compare the data of @p list
 * @param order     The sort direction, possible values are ECORE_SORT_MIN and
 *                  ECORE_SORT_MAX
 * @return          true on success
 *
 * Mergesort is a stable, in-place sorting algorithm
 */
EAPI int
ecore_list_mergesort(Ecore_List *list, Ecore_Compare_Cb compare, char order)
{
   Ecore_List_Node *node;

   CHECK_PARAM_POINTER_RETURN("list", list, 0);
   if (list->nodes < 2)
      return 1;

   if (order == ECORE_SORT_MIN)
      order = 1;
   else
      order = -1;

   node = _ecore_list_node_mergesort(list->first, list->nodes, compare, order);
   list->first = node;

   /* maybe there is a better way to do that but our last node has changed */
   while (node->next)
      node = node->next;
   list->last = node;

   _ecore_list_first_goto(list);

   return 1;
}

/**
 * Merge the @p l2 into the @p list using the compare function @p compare.
 * Both lists need to be sorted else a corrupt list could be the result.
 * @param list      The list.
 * @param l2        The second list, this list will be empty after the merge
 * @param compare   The function to compare the data of @p list and @p l2
 * @param order     The sort direction, possible values are ECORE_SORT_MIN and
 *                  ECORE_SORT_MAX
 */
EAPI void
ecore_list_merge(Ecore_List *list,
                 Ecore_List *l2,
                 Ecore_Compare_Cb compare,
                 char order)
{
   CHECK_PARAM_POINTER("list", list);
   CHECK_PARAM_POINTER("l2",   l2);

   if (ecore_list_empty_is(l2))
      return;

   if (ecore_list_empty_is(list))
     {
        ecore_list_append_list(list, l2);
        return;
     }

   if (order == ECORE_SORT_MIN)
      order = 1;
   else
      order = -1;

   list->first = _ecore_list_node_merge(list->first, l2->first, compare, order);

   if ((order * compare(list->last->data, l2->last->data)) < 0)
      list->last = l2->last;

   list->nodes += l2->nodes;
   ecore_list_init(l2);
}

/* this is the internal recrusive function for the merge sort */
static Ecore_List_Node *
_ecore_list_node_mergesort(Ecore_List_Node *first, int n,
                           Ecore_Compare_Cb compare, int order)
{
   Ecore_List_Node *middle;
   Ecore_List_Node *premid;
   int mid;
   int i;

   mid = n / 2;

   if (n < 2)
      return first;
   else if (n == 2)
     {
        if (compare(first->data, first->next->data) * order > 0)
          {
             /* swap the data */
             void *data;
             data = first->next->data;
             first->next->data = first->data;
             first->data = data;
          }

        return first;
     }

   /* first find the premiddle node*/
   for (premid = first, i = 0; i < mid - 1; i++)
      premid = premid->next;

   /* split the list */
   middle = premid->next;
   premid->next = NULL;

   /* sort the the partial lists */
   first = _ecore_list_node_mergesort(first, mid, compare, order);
   middle = _ecore_list_node_mergesort(middle, n - mid, compare, order);

   return _ecore_list_node_merge(first, middle, compare, order);
}

/* this function is used to merge the partial sorted lists */
static Ecore_List_Node *
_ecore_list_node_merge(Ecore_List_Node *first, Ecore_List_Node *second,
                       Ecore_Compare_Cb compare, int order)
{
   Ecore_List_Node *list;
   Ecore_List_Node *l;

   /* select the first node outside the loop, because we need to keep
    * a pointer to it */
   if (compare(first->data, second->data) * order > 0)
     {
        list = l = second;
        second = second->next;
     }
   else
     {
        list = l = first;
        first = first->next;
     }

   /* and now start the merging */
   while (first && second)
     {
        if (compare(first->data, second->data) * order > 0)
          {
             l = l->next = second;
             second = second->next;
          }
        else
          {
             l = l->next = first;
             first = first->next;
          }
     }

   /* append the rest or set it to NULL */
   if (first)
      l->next = first;
   else if (second)
      l->next = second;
   else
      l->next = NULL;

   return list;
}

/**
 * Sort data in @p list using the compare function @p compare
 * @param list      The list.
 * @param compare   The function to compare the data of @p list
 * @param order     The sort direction, possible values are ECORE_SORT_MIN and
 *                  ECORE_SORT_MAX
 * @return          true on success
 *
 * Heapsort is a unstable sorting algorithm, it needs to allocate extra memomry,
 * but there for it is for a great number of nodes faster than mergesort
 */
EAPI int
ecore_list_heapsort(Ecore_List *list, Ecore_Compare_Cb compare, char order)
{
   Ecore_Sheap *heap;
   Ecore_List_Node *node;
   void *data;

   CHECK_PARAM_POINTER_RETURN("list", list, 0);
   /*
    * Push the data into a heap.
    */
   heap = ecore_sheap_new(compare, list->nodes);
   if (!heap)
      return 0;

   ecore_sheap_order_set(heap, order);
   _ecore_list_first_goto(list);
   while ((data = _ecore_list_next(list)))
     {
        ecore_sheap_insert(heap, data);
     }

   /*
    * Extract in sorted order.
    */
   node = list->first;
   while (node)
     {
        node->data = ecore_sheap_extract(heap);
        node = node->next;
     }

   ecore_sheap_destroy(heap);

   _ecore_list_first_goto(list);
   return 1;
}

/* Initialize a node to starting values */
EAPI int
ecore_list_node_init(Ecore_List_Node *node)
{
   CHECK_PARAM_POINTER_RETURN("node", node, FALSE);

   node->next = NULL;
   node->data = NULL;

   return TRUE;
}

/**
   @defgroup Ecore_Data_List_Node_Group List Node Functions

   Functions that are used in the creation, maintenance and destruction of
   Ecore_List nodes.
 */

/**
 * Allocates and initializes a new list node.
 * @return  A new Ecore_List_Node on success, @c NULL otherwise.
 * @ingroup Ecore_Data_List_Node_Group
 */
EAPI Ecore_List_Node *
ecore_list_node_new()
{
   Ecore_List_Node *new_node;

   new_node = malloc(sizeof(Ecore_List_Node));

   if (!ecore_list_node_init(new_node))
     {
        FREE(new_node);
        return NULL;
     }

   return new_node;
}

/**
 * Calls the function to free the data and the node.
 * @param   node      Node to destroy.
 * @param   free_func Function to call if @p node points to data to free.
 * @return  @c TRUE.
 * @ingroup Ecore_Data_List_Node_Group
 */
EAPI int
ecore_list_node_destroy(Ecore_List_Node *node, Ecore_Free_Cb free_func)
{
   CHECK_PARAM_POINTER_RETURN("node", node, FALSE);

   if (free_func && node->data)
      free_func(node->data);

   FREE(node);

   return TRUE;
}

/**
 * @defgroup Ecore_Data_DList_Creation_Group Doubly Linked List Creation/Destruction Functions
 *
 * Functions used to create, initialize and destroy @c Ecore_DLists.
 */

/**
 * Creates and initialises a new doubly linked list.
 * @return  A new initialised doubly linked list on success, @c NULL
 *          on failure.
 * @ingroup Ecore_Data_DList_Creation_Group
 */
EAPI Ecore_DList *
ecore_dlist_new()
{
   Ecore_DList *list = NULL;

   list = (Ecore_DList *)malloc(sizeof(Ecore_DList));
   if (!list)
      return NULL;

   if (!ecore_dlist_init(list))
     {
        IF_FREE(list);
        return NULL;
     }

   return list;
}

/**
 * Initialises a list to some sane starting values.
 * @param   list The doubly linked list to initialise.
 * @return  @c TRUE if successful, @c FALSE if an error occurs.
 * @ingroup Ecore_Data_DList_Creation_Group
 */
EAPI int
ecore_dlist_init(Ecore_DList *list)
{
   CHECK_PARAM_POINTER_RETURN("list", list, FALSE);

   memset(list, 0, sizeof(Ecore_DList));

   return TRUE;
}

/**
 * Frees a doubly linked list and all of its nodes.
 * @param   list The doubly linked list to be freed.
 * @ingroup Ecore_Data_DList_Creation_Group
 */
EAPI void
ecore_dlist_destroy(Ecore_DList *list)
{
   void *data;
   CHECK_PARAM_POINTER("list", list);

   while (list->first)
     {
        data = _ecore_dlist_first_remove(list);
        if (list->free_func)
           list->free_func(data);
     }

   FREE(list);
}

/**
 * Sets the function used for freeing data stored in a doubly linked list.
 * @param   list      The doubly linked list that will use this function when
 *                    nodes are destroyed.
 * @param   free_func The function that will free the key data
 * @return  @c TRUE on success, @c FALSE on failure.
 * @ingroup Ecore_Data_DList_Creation_Group
 */
EAPI int
ecore_dlist_free_cb_set(Ecore_DList *list, Ecore_Free_Cb free_func)
{
   CHECK_PARAM_POINTER_RETURN("list", list, FALSE);

   return ecore_list_free_cb_set(ECORE_LIST(list), free_func);
}

/**
 * Returns whether there is anything in the given doubly linked list.
 * @param  list The given doubly linked list.
 * @return @c TRUE if there are nodes, @c FALSE otherwise.
 */
EAPI int
ecore_dlist_empty_is(Ecore_DList *list)
{
   CHECK_PARAM_POINTER_RETURN("list", list, FALSE);

   return ecore_list_empty_is(ECORE_LIST(list));
}

/**
 * Retrieves the index of the current node of the given doubly linked list.
 * @param  list The given doubly linked list.
 * @return The index of the current node.
 */
EAPI inline int
ecore_dlist_index(Ecore_DList *list)
{
   CHECK_PARAM_POINTER_RETURN("list", list, FALSE);

   return ecore_list_index(ECORE_LIST(list));
}

/**
 * @defgroup Ecore_Data_DList_Add_Item_Group Doubly Linked List Adding Functions
 *
 * Functions that are used to add nodes to an Ecore_DList.
 */

/**
 * Appends data to the given doubly linked list.
 * @param   list The given doubly linked list.
 * @param   data The data to append.
 * @return  @c TRUE if the data is successfully appended, @c FALSE otherwise.
 * @ingroup Ecore_Data_DList_Add_Item_Group
 */
EAPI int
ecore_dlist_append(Ecore_DList *list, void *data)
{
   int ret;
   Ecore_DList_Node *prev;
   Ecore_DList_Node *node;

   CHECK_PARAM_POINTER_RETURN("list", list, FALSE);

   node = ecore_dlist_node_new();
   ECORE_LIST_NODE(node)->data = data;

   prev = ECORE_DLIST_NODE(ECORE_LIST(list)->last);
   ret = _ecore_list_append_0(ECORE_LIST(list), ECORE_LIST_NODE(node));
   if (ret)
      node->previous = prev;

   return ret;
}

/**
 * Adds data to the very beginning of the given doubly linked list.
 * @param   list The given doubly linked list.
 * @param   data The data to prepend.
 * @return  @c TRUE if the data is successfully prepended, @c FALSE otherwise.
 * @ingroup Ecore_Data_DList_Add_Item_Group
 */
EAPI int
ecore_dlist_prepend(Ecore_DList *list, void *data)
{
   int ret;
   Ecore_DList_Node *prev;
   Ecore_DList_Node *node;

   CHECK_PARAM_POINTER_RETURN("list", list, FALSE);

   node = ecore_dlist_node_new();
   ECORE_LIST_NODE(node)->data = data;

   prev = ECORE_DLIST_NODE(ECORE_LIST(list)->first);
   ret = _ecore_list_prepend_0(ECORE_LIST(list), ECORE_LIST_NODE(node));
   if (ret && prev)
      prev->previous = node;

   return ret;
}

/**
 * Inserts data at the current point in the given doubly linked list.
 * @param   list The given doubly linked list.
 * @param   data The data to be inserted.
 * @return  @c TRUE on success, @c FALSE otherwise.
 * @ingroup Ecore_Data_DList_Add_Item_Group
 */
EAPI int
ecore_dlist_insert(Ecore_DList *list, void *data)
{
   int ret = TRUE;
   Ecore_DList_Node *prev;
   Ecore_DList_Node *node;

   CHECK_PARAM_POINTER_RETURN("list", list, FALSE);

   /*
    * Identify and shortcut the end cases.
    */
   if (!ECORE_LIST(list)->current)
      return ecore_dlist_append(list, data);

   if (ECORE_LIST(list)->current == ECORE_LIST(list)->first)
      return ecore_dlist_prepend(list, data);

   node = ecore_dlist_node_new();
   ECORE_LIST_NODE(node)->data = data;

   /* Setup the fields of the new node */
   ECORE_LIST_NODE(node)->next = ECORE_LIST(list)->current;

   /* And hook the node into the list */
   prev = ECORE_DLIST_NODE(ECORE_LIST(list)->current)->previous;
   ECORE_LIST_NODE(prev)->next = ECORE_LIST_NODE(node);
   ECORE_DLIST_NODE(ECORE_LIST(list)->current)->previous = node;
   node->previous = prev;

   /* Now move the current item to the inserted item */
   ECORE_LIST(list)->current = ECORE_LIST_NODE(node);
   ECORE_LIST(list)->nodes++;

   return ret;
}

/**
 * Appends a list to the given doubly linked list.
 * @param   list The given doubly linked list.
 * @param   append The list to append.
 * @return  @c TRUE if the data is successfully appended, @c FALSE otherwise.
 * @ingroup Ecore_Data_DList_Add_Item_Group
 */
EAPI int
ecore_dlist_append_list(Ecore_DList *list, Ecore_DList *append)
{
   CHECK_PARAM_POINTER_RETURN("list",   list,   FALSE);
   CHECK_PARAM_POINTER_RETURN("append", append, FALSE);

   if (ecore_dlist_empty_is(append))
      return TRUE;

   if (ecore_dlist_empty_is(list))
     {
        list->first = append->first;
        list->current = NULL;
        list->last = append->last;
        list->nodes = append->nodes;
     }
   else
     {
        list->last->next = append->first;
        ECORE_DLIST_NODE(append->first)->previous = ECORE_DLIST_NODE(list->last);
        list->last = append->last;
        list->nodes += append->nodes;
     }

   ecore_dlist_init(append);
   return TRUE;
}

/**
 * Adds a list to the very beginning of the given doubly linked list.
 * @param   list The given doubly linked list.
 * @param   prepend The list to prepend.
 * @return  @c TRUE if the data is successfully prepended, @c FALSE otherwise.
 * @ingroup Ecore_Data_DList_Add_Item_Group
 */
EAPI int
ecore_dlist_prepend_list(Ecore_DList *list, Ecore_DList *prepend)
{
   CHECK_PARAM_POINTER_RETURN("list",    list,    FALSE);
   CHECK_PARAM_POINTER_RETURN("prepend", prepend, FALSE);

   if (ecore_dlist_empty_is(prepend))
      return TRUE;

   if (ecore_dlist_empty_is(list))
     {
        list->first = prepend->first;
        list->current = NULL;
        list->last = prepend->last;
        list->nodes = prepend->nodes;
     }
   else
     {
        prepend->last->next = list->first;
        ECORE_DLIST_NODE(list->first)->previous = ECORE_DLIST_NODE(
              prepend->last);
        list->first = prepend->first;
        list->nodes += prepend->nodes;
        list->index += prepend->nodes;
     }

   ecore_dlist_init(prepend);
   return TRUE;
}

/**
 * @defgroup Ecore_Data_DList_Remove_Item_Group Doubly Linked List Removing Functions
 *
 * Functions that remove nodes from an @c Ecore_DList.
 */

/**
 * Removes the current item from the given doubly linked list.
 * @param   list The given doubly linked list.
 * @return  A pointer to the removed data on success, @c NULL otherwise.
 * @ingroup Ecore_Data_DList_Remove_Item_Group
 */
EAPI void *
ecore_dlist_remove(Ecore_DList *list)
{
   void *ret;
   Ecore_List *l2 = ECORE_LIST(list);
   Ecore_DList_Node *node;

   CHECK_PARAM_POINTER_RETURN("list", list, NULL);

   if (l2->current)
     {
        node = ECORE_DLIST_NODE(list->current->next);
        if (node)
           node->previous = ECORE_DLIST_NODE(l2->current)->previous;
     }

   ret = _ecore_list_remove_0(list);

   return ret;
}

/**
 * Removes the first item from the given doubly linked list.
 * @param   list The given doubly linked list.
 * @return  A pointer to the removed data on success, @c NULL on failure.
 * @ingroup Ecore_Data_DList_Remove_Item_Group
 */
EAPI void *
ecore_dlist_first_remove(Ecore_DList *list)
{
   void *ret;

   CHECK_PARAM_POINTER_RETURN("list", list, NULL);

   ret = _ecore_dlist_first_remove(list);

   return ret;
}

/**
 * Removes and frees the data at the current position in the given doubly
 * linked list.
 * @param   list The given doubly linked list.
 * @return  @c TRUE on success, @c FALSE otherwise.
 * @ingroup Ecore_Data_DList_Remove_Item_Group
 */
EAPI int
ecore_dlist_remove_destroy(Ecore_DList *list)
{
   void *data;

   CHECK_PARAM_POINTER_RETURN("list", list, FALSE);

   data = ecore_dlist_remove(list);
   if (!data)
      return FALSE;

   if (list->free_func)
      list->free_func(data);

   return TRUE;
}

static void *
_ecore_dlist_first_remove(Ecore_DList *list)
{
   void *ret;

   if (!list)
      return NULL;

   ret = _ecore_list_first_remove(list);
   if (ret && ECORE_LIST(list)->first)
      ECORE_DLIST_NODE(ECORE_LIST(list)->first)->previous = NULL;

   return ret;
}

/**
 * Removes the last item from the given doubly linked list.
 * @param   list The given doubly linked list.
 * @return  A pointer to the removed data on success, @c NULL otherwise.
 * @ingroup Ecore_Data_DList_Remove_Item_Group
 */
EAPI void *
ecore_dlist_last_remove(Ecore_DList *list)
{
   void *ret;
   Ecore_List_Node *node;

   CHECK_PARAM_POINTER_RETURN("list", list, NULL);

   if (ecore_list_empty_is(list))
      return NULL;

   node = list->last;
   list->last = ECORE_LIST_NODE(ECORE_DLIST_NODE(node)->previous);
   if (list->last)
      list->last->next = NULL;

   if (list->first == node)
      list->first = NULL;

   if (list->current == node)
      list->current = NULL;

   ret = node->data;
   ecore_list_node_destroy(node, NULL);

   list->nodes--;
   if (list->index >= list->nodes)
      list->index--;

   return ret;
}

/**
 * Moves the current item to the index number in the given doubly linked list.
 * @param  list  The given doubly linked list.
 * @param  idx The position to move the current item
 * @return The node at specified index on success, @c NULL on error.
 */
EAPI void *
ecore_dlist_index_goto(Ecore_DList *list, int idx)
{
   void *ret;

   CHECK_PARAM_POINTER_RETURN("list", list, NULL);

   ret = _ecore_dlist_index_goto(list, idx);

   return ret;
}

/* This is the non-threadsafe version, use this inside internal functions that
 * already lock the list */
static void *
_ecore_dlist_index_goto(Ecore_DList *list, int idx)
{
   int i, increment;

   if (!list)
      return NULL;

   if (ecore_list_empty_is(ECORE_LIST(list)))
      return NULL;

   if (idx > ecore_list_count(ECORE_LIST(list)) || idx < 0)
      return NULL;

   if (ECORE_LIST(list)->index >= ECORE_LIST(list)->nodes)
      _ecore_list_last_goto(ECORE_LIST(list));

   if (idx < ECORE_LIST(list)->index)
      increment = -1;
   else
      increment = 1;

   for (i = ECORE_LIST(list)->index; i != idx; i += increment)
     {
        if (increment > 0)
           _ecore_list_next(list);
        else
           _ecore_dlist_previous(list);
     }

   return _ecore_list_current(list);
}

/**
 * @brief Move the current item to the node that contains data
 * @param list: the list to move the current item in
 * @param data: the data to find and set the current item to
 *
 * @return Returns specified data on success, NULL on error
 */
EAPI void *
ecore_dlist_goto(Ecore_DList *list, void *data)
{
   void *ret;

   CHECK_PARAM_POINTER_RETURN("list", list, NULL);

   ret = _ecore_list_goto(ECORE_LIST(list), data);

   return ret;
}

/**
 * @brief Move the current pointer to the first item in the list
 * @param list: the list to change the current to the first item
 *
 * @return Returns a pointer to the first item on success, NULL on failure.
 */
EAPI void *
ecore_dlist_first_goto(Ecore_DList *list)
{
   void *ret;

   CHECK_PARAM_POINTER_RETURN("list", list, NULL);

   ret = _ecore_list_first_goto(list);

   return ret;
}

/**
 * @brief Move the pointer to the current item to the last item
 * @param list: the list to move the current item pointer to the last
 * @return Returns a pointer to the last item in the list , NULL if empty.
 */
EAPI void *
ecore_dlist_last_goto(Ecore_DList *list)
{
   void *ret;

   CHECK_PARAM_POINTER_RETURN("list", list, NULL);

   ret = _ecore_list_last_goto(ECORE_LIST(list));

   return ret;
}

/**
 * @brief Return the data in the current list item
 * @param list: the list to the return the current data
 * @return Returns value of the current data item, NULL if no current item
 */
EAPI void *
ecore_dlist_current(Ecore_DList *list)
{
   void *ret;

   ret = _ecore_list_current(ECORE_LIST(list));

   return ret;
}

/**
 * @brief Move to the next item in the list and return current item
 * @param list: the list to move to the next item in.
 * @return Returns data in the current list node, or NULL on error
 */
EAPI void *
ecore_dlist_next(Ecore_DList *list)
{
   void *data;

   data = _ecore_list_next(list);

   return data;
}

/**
 * @brief Move to the previous item and return current item
 * @param list: the list to move to the previous item in.
 * @return Returns data in the current list node, or NULL on error
 */
EAPI void *
ecore_dlist_previous(Ecore_DList *list)
{
   void *data;

   data = _ecore_dlist_previous(list);

   return data;
}

static void *
_ecore_dlist_previous(Ecore_DList *list)
{
   void *data = NULL;

   if (!list)
      return NULL;

   if (ECORE_LIST(list)->current)
     {
        data = ECORE_LIST(list)->current->data;
                                     ECORE_LIST(list)->
        current = ECORE_LIST_NODE(ECORE_DLIST_NODE(
                                     ECORE_LIST(list)->
                                     current)->previous);
                                     ECORE_LIST(list)->index
        --;
     }
   else
      _ecore_list_last_goto(
         ECORE_LIST(list));

   return data;
}

/**
 * @brief Remove all nodes from the list.
 * @param list: the list to remove all nodes from
 *
 * @return Returns TRUE on success, FALSE on errors
 */
EAPI int
ecore_dlist_clear(Ecore_DList *list)
{
   CHECK_PARAM_POINTER_RETURN("list", list, FALSE);

   ecore_list_clear(ECORE_LIST(list));

   return TRUE;
}

/**
 * Sort data in @p list using the compare function @p compare
 * @param list      The list.
 * @param compare   The function to compare the data of @p list
 * @param order     The sort direction, possible values are ECORE_SORT_MIN and
 *                  ECORE_SORT_MAX
 * @return          true on success
 *
 * This is a wrapper function for mergesort and heapsort. It
 * tries to choose the fastest algorithm depending on the
 * number of notes. Note: The sort may be unstable.
 */
EAPI int
ecore_dlist_sort(Ecore_List *list, Ecore_Compare_Cb compare, char order)
{
   CHECK_PARAM_POINTER_RETURN("list", list, 0);

   if (list->nodes < 2)
      return 1;

   if (list->nodes < ECORE_MERGESORT_LIMIT)
      return ecore_dlist_mergesort(list, compare, order);

   if (!ecore_dlist_heapsort(list, compare, order))
      return ecore_dlist_mergesort(list, compare, order);

   return 1;
}

/**
 * Sort data in @p list using the compare function @p compare
 * @param list      The list.
 * @param compare   The function to compare the data of @p list
 * @param order     The sort direction, possible values are ECORE_SORT_MIN and
 *                  ECORE_SORT_MAX
 * @return          true on success
 *
 * Mergesort is a stable, in-place sorting algorithm
 */
EAPI int
ecore_dlist_mergesort(Ecore_DList *list, Ecore_Compare_Cb compare, char order)
{
   Ecore_List_Node *node;

   CHECK_PARAM_POINTER_RETURN("list", list, 0);
   if (list->nodes < 2)
      return 1;

   if (order == ECORE_SORT_MIN)
      order = 1;
   else
      order = -1;

   node = _ecore_dlist_node_mergesort(list->first, list->nodes, compare, order);
   list->first = node;

   /* maybe there is a better way to do that but our last node has changed */
   while (node->next)
      node = node->next;
   list->last = node;

   _ecore_list_first_goto(list);

   return 1;
}

/**
 * Merge the @p l2 into the @p list using the compare function @p compare.
 * Both lists need to be sorted else a corrupt list could be the result.
 * @param list      The list.
 * @param l2        The second list, this list will be empty after the merge
 * @param compare   The function to compare the data of @p list and @p l2
 * @param order     The sort direction, possible values are ECORE_SORT_MIN and
 *                  ECORE_SORT_MAX
 */
EAPI void
ecore_dlist_merge(Ecore_DList *list,
                  Ecore_DList *l2,
                  Ecore_Compare_Cb compare,
                  char order)
{
   CHECK_PARAM_POINTER("list", list);
   CHECK_PARAM_POINTER("l2",   l2);

   if (ecore_dlist_empty_is(l2))
      return;

   if (ecore_dlist_empty_is(list))
     {
        ecore_dlist_append_list(list, l2);
        return;
     }

   if (order == ECORE_SORT_MIN)
      order = 1;
   else
      order = -1;

   list->first = _ecore_dlist_node_merge(list->first, l2->first, compare, order);

   if ((order * compare(list->last->data, l2->last->data)) < 0)
      list->last = l2->last;

   list->nodes += l2->nodes;
   ecore_dlist_init(l2);
}

/* this is the internal recrusive function for the merge sort */
static Ecore_List_Node *
_ecore_dlist_node_mergesort(Ecore_List_Node *first, int n,
                            Ecore_Compare_Cb compare, int order)
{
   Ecore_List_Node *middle;
   Ecore_List_Node *premid;
   int mid;
   int i;

   mid = n / 2;

   if (n < 2)
      return first;
   else if (n == 2)
     {
        if (compare(first->data, first->next->data) * order > 0)
          {
             /* swap the data */
             void *data;
             data = first->next->data;
             first->next->data = first->data;
             first->data = data;
          }

        return first;
     }

   /* first find the premiddle node*/
   for (premid = first, i = 0; i < mid - 1; i++)
      premid = premid->next;

   /* split the list */
   middle = premid->next;
   premid->next = NULL;
             ECORE_DLIST_NODE(middle)->previous = NULL;

   /* sort the the partial lists */
   first = _ecore_dlist_node_mergesort(first, mid, compare, order);
   middle = _ecore_dlist_node_mergesort(middle, n - mid, compare, order);

   return _ecore_dlist_node_merge(first, middle, compare, order);
}

/* this function is used to merge the partial sorted lists */
static Ecore_List_Node *
_ecore_dlist_node_merge(Ecore_List_Node *first, Ecore_List_Node *second,
                        Ecore_Compare_Cb compare, int order)
{
   Ecore_List_Node *list;
   Ecore_List_Node *l;

   /* select the first node outside the loop, because we need to keep
    * a pointer to it */
   if (compare(first->data, second->data) * order > 0)
     {
        list = l = second;
        second = second->next;
     }
   else
     {
        list = l = first;
        first = first->next;
     }

   /* and now start the merging */
   while (first && second)
     {
        if (compare(first->data, second->data) * order > 0)
          {
             ECORE_DLIST_NODE(second)->previous = ECORE_DLIST_NODE(l);
             l = l->next = second;
             second = second->next;
          }
        else
          {
             ECORE_DLIST_NODE(first)->previous = ECORE_DLIST_NODE(l);
             l = l->next = first;
             first = first->next;
          }
     }

   /* append the rest or set it to NULL */
   if (first)
     {
             ECORE_DLIST_NODE(first)->previous = ECORE_DLIST_NODE(l);
        l->next = first;
     }
   else if (second)
     {
             ECORE_DLIST_NODE(second)->previous = ECORE_DLIST_NODE(l);
        l->next = second;
     }
   else
      l->next = NULL;

   return list;
}

/*
 * @brief Initialize a node to sane starting values
 * @param node: the node to initialize
 * @return Returns TRUE on success, FALSE on errors
 */
EAPI int
ecore_dlist_node_init(Ecore_DList_Node *node)
{
   int ret;

   CHECK_PARAM_POINTER_RETURN("node", node, FALSE);

   ret = ecore_list_node_init(ECORE_LIST_NODE(node));
   if (ret)
      node->previous = NULL;

   return ret;
}

/*
 * @brief Allocate and initialize a new list node
 * @return Returns NULL on error, new list node on success
 */
EAPI Ecore_DList_Node *
ecore_dlist_node_new()
{
   Ecore_DList_Node *new_node;

   new_node = malloc(sizeof(Ecore_DList_Node));

   if (!new_node)
      return NULL;

   if (!ecore_dlist_node_init(new_node))
     {
        FREE(new_node);
        return NULL;
     }

   return new_node;
}

/*
 * @brief Call the data's free callback function, then free the node
 * @param node: the node to be freed
 * @param free_func: the callback function to execute on the data
 * @return Returns TRUE on success, FALSE on error
 */
EAPI int
ecore_dlist_node_destroy(Ecore_DList_Node *node, Ecore_Free_Cb free_func)
{
   CHECK_PARAM_POINTER_RETURN("node", node, FALSE);

   return ecore_list_node_destroy(ECORE_LIST_NODE(node), free_func);
}