/* GLIB - Library of useful routines for C programming

 * Copyright (C) 1995-1997  Peter Mattis, Spencer Kimball and Josh MacDonald

 *

 * 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/>.

 */

/*

 * Modified by the GLib Team and others 1997-2000.  See the AUTHORS

 * file for a list of people on the GLib Team.  See the ChangeLog

 * files for a list of changes.  These files are distributed with

 * GLib at ftp://ftp.gtk.org/pub/gtk/.

 */

/*

 * MT safe

 */

#include "config.h"

#include "glist.h"

#include "gslice.h"

#include "gmessages.h"

#include "gtestutils.h"

/**

 * SECTION:linked_lists_double

 * @title: Doubly-Linked Lists

 * @short_description: linked lists that can be iterated over in both directions

 *

 * The #GList structure and its associated functions provide a standard

 * doubly-linked list data structure.

 *

 * Each element in the list contains a piece of data, together with

 * pointers which link to the previous and next elements in the list.

 * Using these pointers it is possible to move through the list in both

 * directions (unlike the singly-linked [GSList][glib-Singly-Linked-Lists],

 * which only allows movement through the list in the forward direction).

 *

 * The double linked list does not keep track of the number of items 

 * and does not keep track of both the start and end of the list. If

 * you want fast access to both the start and the end of the list, 

 * and/or the number of items in the list, use a

 * [GQueue][glib-Double-ended-Queues] instead.

 *

 * The data contained in each element can be either integer values, by

 * using one of the [Type Conversion Macros][glib-Type-Conversion-Macros],

 * or simply pointers to any type of data.

 *

 * List elements are allocated from the [slice allocator][glib-Memory-Slices],

 * which is more efficient than allocating elements individually.

 *

 * Note that most of the #GList functions expect to be passed a pointer

 * to the first element in the list. The functions which insert

 * elements return the new start of the list, which may have changed.

 *

 * There is no function to create a #GList. %NULL is considered to be

 * a valid, empty list so you simply set a #GList* to %NULL to initialize

 * it.

 *

 * To add elements, use g_list_append(), g_list_prepend(),

 * g_list_insert() and g_list_insert_sorted().

 *

 * To visit all elements in the list, use a loop over the list:

 * |[

 * GList *l;

 * for (l = list; l != NULL; l = l->next)

 *   {

 *     // do something with l->data

 *   }

 * ]|

 *

 * To call a function for each element in the list, use g_list_foreach().

 *

 * To loop over the list and modify it (e.g. remove a certain element)

 * a while loop is more appropriate, for example:

 * |[

 * GList *l = list;

 * while (l != NULL)

 *   {

 *     GList *next = l->next;

 *     if (should_be_removed (l))

 *       {

 *         // possibly free l->data

 *         list = g_list_delete_link (list, l);

 *       }

 *     l = next;

 *   }

 * ]|

 *

 * To remove elements, use g_list_remove().

 *

 * To navigate in a list, use g_list_first(), g_list_last(),

 * g_list_next(), g_list_previous().

 *

 * To find elements in the list use g_list_nth(), g_list_nth_data(),

 * g_list_find() and g_list_find_custom().

 *

 * To find the index of an element use g_list_position() and

 * g_list_index().

 *

 * To free the entire list, use g_list_free() or g_list_free_full().

 */

/**

 * GList:

 * @data: holds the element's data, which can be a pointer to any kind

 *        of data, or any integer value using the 

 *        [Type Conversion Macros][glib-Type-Conversion-Macros]

 * @next: contains the link to the next element in the list

 * @prev: contains the link to the previous element in the list

 *

 * The #GList struct is used for each element in a doubly-linked list.

 **/

/**

 * g_list_previous:

 * @list: an element in a #GList

 *

 * A convenience macro to get the previous element in a #GList.

 * Note that it is considered perfectly acceptable to access

 * @list->prev directly.

 *

 * Returns: the previous element, or %NULL if there are no previous

 *          elements

 **/

/**

 * g_list_next:

 * @list: an element in a #GList

 *

 * A convenience macro to get the next element in a #GList.

 * Note that it is considered perfectly acceptable to access

 * @list->next directly.

 *

 * Returns: the next element, or %NULL if there are no more elements

 **/

#define _g_list_alloc()         g_slice_new (GList)

#define _g_list_alloc0()        g_slice_new0 (GList)

#define _g_list_free1(list)     g_slice_free (GList, list)

/**

 * g_list_alloc:

 *

 * Allocates space for one #GList element. It is called by

 * g_list_append(), g_list_prepend(), g_list_insert() and

 * g_list_insert_sorted() and so is rarely used on its own.

 *

 * Returns: a pointer to the newly-allocated #GList element

 **/

GList *

g_list_alloc (void)

{

  return _g_list_alloc0 ();

}

/**

 * g_list_free: 

 * @list: a #GList

 *

 * Frees all of the memory used by a #GList.

 * The freed elements are returned to the slice allocator.

 *

 * If list elements contain dynamically-allocated memory, you should

 * either use g_list_free_full() or free them manually first.

 */

void

g_list_free (GList *list)

{

  g_slice_free_chain (GList, list, next);

}

/**

 * g_list_free_1:

 * @list: a #GList element

 *

 * Frees one #GList element, but does not update links from the next and

 * previous elements in the list, so you should not call this function on an

 * element that is currently part of a list.

 *

 * It is usually used after g_list_remove_link().

 */

/**

 * g_list_free1:

 *

 * Another name for g_list_free_1().

 **/

void

g_list_free_1 (GList *list)

{

  _g_list_free1 (list);

}

/**

 * g_list_free_full:

 * @list: a pointer to a #GList

 * @free_func: the function to be called to free each element's data

 *

 * Convenience method, which frees all the memory used by a #GList,

 * and calls @free_func on every element's data.

 *

 * @free_func must not modify the list (eg, by removing the freed

 * element from it).

 *

 * Since: 2.28

 */

void

g_list_free_full (GList          *list,

                  GDestroyNotify  free_func)

{

  g_list_foreach (list, (GFunc) free_func, NULL);

  g_list_free (list);

}

/**

 * g_list_append:

 * @list: a pointer to a #GList

 * @data: the data for the new element

 *

 * Adds a new element on to the end of the list.

 *

 * Note that the return value is the new start of the list,

 * if @list was empty; make sure you store the new value.

 *

 * g_list_append() has to traverse the entire list to find the end,

 * which is inefficient when adding multiple elements. A common idiom

 * to avoid the inefficiency is to use g_list_prepend() and reverse

 * the list with g_list_reverse() when all elements have been added.

 *

 * |[

 * // Notice that these are initialized to the empty list.

 * GList *string_list = NULL, *number_list = NULL;

 *

 * // This is a list of strings.

 * string_list = g_list_append (string_list, "first");

 * string_list = g_list_append (string_list, "second");

 * 

 * // This is a list of integers.

 * number_list = g_list_append (number_list, GINT_TO_POINTER (27));

 * number_list = g_list_append (number_list, GINT_TO_POINTER (14));

 * ]|

 *

 * Returns: either @list or the new start of the #GList if @list was %NULL

 */

GList *

g_list_append (GList    *list,

               gpointer  data)

{

  GList *new_list;

  GList *last;

  new_list = _g_list_alloc ();

  new_list->data = data;

  new_list->next = NULL;

  if (list)

    {

      last = g_list_last (list);

      /* g_assert (last != NULL); */

      last->next = new_list;

      new_list->prev = last;

      return list;

    }

  else

    {

      new_list->prev = NULL;

      return new_list;

    }

}

/**

 * g_list_prepend:

 * @list: a pointer to a #GList, this must point to the top of the list

 * @data: the data for the new element

 *

 * Prepends a new element on to the start of the list.

 *

 * Note that the return value is the new start of the list,

 * which will have changed, so make sure you store the new value. 

 *

 * |[

 * // Notice that it is initialized to the empty list.

 * GList *list = NULL;

 *

 * list = g_list_prepend (list, "last");

 * list = g_list_prepend (list, "first");

 * ]|

 *

 * Do not use this function to prepend a new element to a different

 * element than the start of the list. Use g_list_insert_before() instead.

 *

 * Returns: a pointer to the newly prepended element, which is the new 

 *     start of the #GList

 */

GList *

g_list_prepend (GList    *list,

                gpointer  data)

{

  GList *new_list;

  new_list = _g_list_alloc ();

  new_list->data = data;

  new_list->next = list;

  if (list)

    {

      new_list->prev = list->prev;

      if (list->prev)

        list->prev->next = new_list;

      list->prev = new_list;

    }

  else

    new_list->prev = NULL;

  return new_list;

}

/**

 * g_list_insert:

 * @list: a pointer to a #GList, this must point to the top of the list

 * @data: the data for the new element

 * @position: the position to insert the element. If this is 

 *     negative, or is larger than the number of elements in the 

 *     list, the new element is added on to the end of the list.

 * 

 * Inserts a new element into the list at the given position.

 *

 * Returns: the (possibly changed) start of the #GList

 */

GList *

g_list_insert (GList    *list,

               gpointer  data,

               gint      position)

{

  GList *new_list;

  GList *tmp_list;

  if (position < 0)

    return g_list_append (list, data);

  else if (position == 0)

    return g_list_prepend (list, data);

  tmp_list = g_list_nth (list, position);

  if (!tmp_list)

    return g_list_append (list, data);

  new_list = _g_list_alloc ();

  new_list->data = data;

  new_list->prev = tmp_list->prev;

  tmp_list->prev->next = new_list;

  new_list->next = tmp_list;

  tmp_list->prev = new_list;

  return list;

}

/**

 * g_list_insert_before:

 * @list: a pointer to a #GList, this must point to the top of the list

 * @sibling: the list element before which the new element 

 *     is inserted or %NULL to insert at the end of the list

 * @data: the data for the new element

 *

 * Inserts a new element into the list before the given position.

 *

 * Returns: the (possibly changed) start of the #GList

 */

GList *

g_list_insert_before (GList    *list,

                      GList    *sibling,

                      gpointer  data)

{

  if (!list)

    {

      list = g_list_alloc ();

      list->data = data;

      g_return_val_if_fail (sibling == NULL, list);

      return list;

    }

  else if (sibling)

    {

      GList *node;

      node = _g_list_alloc ();

      node->data = data;

      node->prev = sibling->prev;

      node->next = sibling;

      sibling->prev = node;

      if (node->prev)

        {

          node->prev->next = node;

          return list;

        }

      else

        {

          g_return_val_if_fail (sibling == list, node);

          return node;

        }

    }

  else

    {

      GList *last;

      last = list;

      while (last->next)

        last = last->next;

      last->next = _g_list_alloc ();

      last->next->data = data;

      last->next->prev = last;

      last->next->next = NULL;

      return list;

    }

}

/**

 * g_list_concat:

 * @list1: a #GList, this must point to the top of the list

 * @list2: the #GList to add to the end of the first #GList,

 *     this must point  to the top of the list

 *

 * Adds the second #GList onto the end of the first #GList.

 * Note that the elements of the second #GList are not copied.

 * They are used directly.

 *

 * This function is for example used to move an element in the list.

 * The following example moves an element to the top of the list:

 * |[

 * list = g_list_remove_link (list, llink);

 * list = g_list_concat (llink, list);

 * ]|

 *

 * Returns: the start of the new #GList, which equals @list1 if not %NULL 

 */

GList *

g_list_concat (GList *list1,

               GList *list2)

{

  GList *tmp_list;

  if (list2)

    {

      tmp_list = g_list_last (list1);

      if (tmp_list)

        tmp_list->next = list2;

      else

        list1 = list2;

      list2->prev = tmp_list;

    }

  return list1;

}

static inline GList *

_g_list_remove_link (GList *list,

                     GList *link)

{

  if (link == NULL)

    return list;

  if (link->prev)

    {

      if (link->prev->next == link)

        link->prev->next = link->next;

      else

        g_warning ("corrupted double-linked list detected");

    }

  if (link->next)

    {

      if (link->next->prev == link)

        link->next->prev = link->prev;

      else

        g_warning ("corrupted double-linked list detected");

    }

  if (link == list)

    list = list->next;

  link->next = NULL;

  link->prev = NULL;

  return list;

}

/**

 * g_list_remove:

 * @list: a #GList, this must point to the top of the list

 * @data: the data of the element to remove

 *

 * Removes an element from a #GList.

 * If two elements contain the same data, only the first is removed.

 * If none of the elements contain the data, the #GList is unchanged.

 *

 * Returns: the (possibly changed) start of the #GList

 */

GList *

g_list_remove (GList         *list,

               gconstpointer  data)

{

  GList *tmp;

  tmp = list;

  while (tmp)

    {

      if (tmp->data != data)

        tmp = tmp->next;

      else

        {

          list = _g_list_remove_link (list, tmp);

          _g_list_free1 (tmp);

          break;

        }

    }

  return list;

}

/**

 * g_list_remove_all:

 * @list: a #GList, this must point to the top of the list

 * @data: data to remove

 *

 * Removes all list nodes with data equal to @data.

 * Returns the new head of the list. Contrast with

 * g_list_remove() which removes only the first node

 * matching the given data.

 *

 * Returns: the (possibly changed) start of the #GList

 */

GList *

g_list_remove_all (GList         *list,

                   gconstpointer  data)

{

  GList *tmp = list;

  while (tmp)

    {

      if (tmp->data != data)

        tmp = tmp->next;

      else

        {

          GList *next = tmp->next;

          if (tmp->prev)

            tmp->prev->next = next;

          else

            list = next;

          if (next)

            next->prev = tmp->prev;

          _g_list_free1 (tmp);

          tmp = next;

        }

    }

  return list;

}

/**

 * g_list_remove_link:

 * @list: a #GList, this must point to the top of the list

 * @llink: an element in the #GList

 *

 * Removes an element from a #GList, without freeing the element.

 * The removed element's prev and next links are set to %NULL, so 

 * that it becomes a self-contained list with one element.

 *

 * This function is for example used to move an element in the list

 * (see the example for g_list_concat()) or to remove an element in

 * the list before freeing its data:

 * |[ 

 * list = g_list_remove_link (list, llink);

 * free_some_data_that_may_access_the_list_again (llink->data);

 * g_list_free (llink);

 * ]|

 *

 * Returns: the (possibly changed) start of the #GList

 */

GList *

g_list_remove_link (GList *list,

                    GList *llink)

{

  return _g_list_remove_link (list, llink);

}

/**

 * g_list_delete_link:

 * @list: a #GList, this must point to the top of the list

 * @link_: node to delete from @list

 *

 * Removes the node link_ from the list and frees it. 

 * Compare this to g_list_remove_link() which removes the node 

 * without freeing it.

 *

 * Returns: the (possibly changed) start of the #GList

 */

GList *

g_list_delete_link (GList *list,

                    GList *link_)

{

  list = _g_list_remove_link (list, link_);

  _g_list_free1 (link_);

  return list;

}

/**

 * g_list_copy:

 * @list: a #GList, this must point to the top of the list

 *

 * Copies a #GList.

 *

 * Note that this is a "shallow" copy. If the list elements 

 * consist of pointers to data, the pointers are copied but 

 * the actual data is not. See g_list_copy_deep() if you need

 * to copy the data as well.

 *

 * Returns: the start of the new list that holds the same data as @list

 */

GList *

g_list_copy (GList *list)

{

  return g_list_copy_deep (list, NULL, NULL);

}

/**

 * g_list_copy_deep:

 * @list: a #GList, this must point to the top of the list

 * @func: a copy function used to copy every element in the list

 * @user_data: user data passed to the copy function @func, or %NULL

 *

 * Makes a full (deep) copy of a #GList.

 *

 * In contrast with g_list_copy(), this function uses @func to make

 * a copy of each list element, in addition to copying the list

 * container itself.

 *

 * @func, as a #GCopyFunc, takes two arguments, the data to be copied

 * and a @user_data pointer. It's safe to pass %NULL as user_data,

 * if the copy function takes only one argument.

 *

 * For instance, if @list holds a list of GObjects, you can do:

 * |[   

 * another_list = g_list_copy_deep (list, (GCopyFunc) g_object_ref, NULL);

 * ]|

 *

 * And, to entirely free the new list, you could do:

 * |[ 

 * g_list_free_full (another_list, g_object_unref);

 * ]|

 *

 * Returns: the start of the new list that holds a full copy of @list, 

 *     use g_list_free_full() to free it

 *

 * Since: 2.34

 */

GList *

g_list_copy_deep (GList     *list,

                  GCopyFunc  func,

                  gpointer   user_data)

{

  GList *new_list = NULL;

  if (list)

    {

      GList *last;

      new_list = _g_list_alloc ();

      if (func)

        new_list->data = func (list->data, user_data);

      else

        new_list->data = list->data;

      new_list->prev = NULL;

      last = new_list;

      list = list->next;

      while (list)

        {

          last->next = _g_list_alloc ();

          last->next->prev = last;

          last = last->next;

          if (func)

            last->data = func (list->data, user_data);

          else

            last->data = list->data;

          list = list->next;

        }

      last->next = NULL;

    }

  return new_list;

}

/**

 * g_list_reverse:

 * @list: a #GList, this must point to the top of the list

 *

 * Reverses a #GList.

 * It simply switches the next and prev pointers of each element.

 *

 * Returns: the start of the reversed #GList

 */

GList *

g_list_reverse (GList *list)

{

  GList *last;

  last = NULL;

  while (list)

    {

      last = list;

      list = last->next;

      last->next = last->prev;

      last->prev = list;

    }

  return last;

}

/**

 * g_list_nth:

 * @list: a #GList, this must point to the top of the list

 * @n: the position of the element, counting from 0

 *

 * Gets the element at the given position in a #GList.

 *

 * This iterates over the list until it reaches the @n-th position. If you

 * intend to iterate over every element, it is better to use a for-loop as

 * described in the #GList introduction.

 *

 * Returns: the element, or %NULL if the position is off 

 *     the end of the #GList

 */

GList *

g_list_nth (GList *list,

            guint  n)

{

  while ((n-- > 0) && list)

    list = list->next;

  return list;

}

/**

 * g_list_nth_prev:

 * @list: a #GList

 * @n: the position of the element, counting from 0

 *

 * Gets the element @n places before @list.

 *

 * Returns: the element, or %NULL if the position is 

 *     off the end of the #GList

 */

GList *

g_list_nth_prev (GList *list,

                 guint  n)

{

  while ((n-- > 0) && list)

    list = list->prev;

  return list;

}

/**

 * g_list_nth_data:

 * @list: a #GList, this must point to the top of the list

 * @n: the position of the element

 *

 * Gets the data of the element at the given position.

 *

 * This iterates over the list until it reaches the @n-th position. If you

 * intend to iterate over every element, it is better to use a for-loop as

 * described in the #GList introduction.

 *

 * Returns: the element's data, or %NULL if the position 

 *     is off the end of the #GList

 */

gpointer

g_list_nth_data (GList *list,

                 guint  n)

{

  while ((n-- > 0) && list)

    list = list->next;

  return list ? list->data : NULL;

}

/**

 * g_list_find:

 * @list: a #GList, this must point to the top of the list

 * @data: the element data to find

 *

 * Finds the element in a #GList which contains the given data.

 *

 * Returns: the found #GList element, or %NULL if it is not found

 */

GList *

g_list_find (GList         *list,

             gconstpointer  data)

{

  while (list)

    {

      if (list->data == data)

        break;

      list = list->next;

    }

  return list;

}

/**

 * g_list_find_custom:

 * @list: a #GList, this must point to the top of the list

 * @data: user data passed to the function

 * @func: the function to call for each element. 

 *     It should return 0 when the desired element is found

 *

 * Finds an element in a #GList, using a supplied function to 

 * find the desired element. It iterates over the list, calling 

 * the given function which should return 0 when the desired 

 * element is found. The function takes two #gconstpointer arguments, 

 * the #GList element's data as the first argument and the 

 * given user data.

 *

 * Returns: the found #GList element, or %NULL if it is not found

 */

GList *

g_list_find_custom (GList         *list,

                    gconstpointer  data,

                    GCompareFunc   func)

{

  g_return_val_if_fail (func != NULL, list);

  while (list)

    {

      if (! func (list->data, data))

        return list;

      list = list->next;

    }

  return NULL;

}

/**

 * g_list_position:

 * @list: a #GList, this must point to the top of the list

 * @llink: an element in the #GList

 *

 * Gets the position of the given element 

 * in the #GList (starting from 0).

 *

 * Returns: the position of the element in the #GList, 

 *     or -1 if the element is not found

 */

gint

g_list_position (GList *list,

                 GList *llink)

{

  gint i;

  i = 0;

  while (list)

    {

      if (list == llink)

        return i;

      i++;

      list = list->next;

    }