glib中单双向链表的归并排序_glib 排序算法

GList *
g_list_sort (GList        *list,
	     GCompareFunc  compare_func)
{
  return g_list_sort_real (list, (GFunc) compare_func, NULL);
			    
}
static GList* 
g_list_sort_real (GList    *list,
		  GFunc     compare_func,
		  gpointer  user_data)
{
  GList *l1, *l2;
  
  if (!list) 
    return NULL;
  if (!list->next) 
    return list;
  
  l1 = list; 
  l2 = list->next;
 
 
  while ((l2 = l2->next) != NULL)
    {
      if ((l2 = l2->next) == NULL) 
	break;
      l1 = l1->next;
    }
  l2 = l1->next;   // 指向链表中间节点
  l1->next = NULL; 
 
 
  return g_list_sort_merge (g_list_sort_real (list, compare_func, user_data),
			    g_list_sort_real (l2, compare_func, user_data),
			    compare_func,
			    user_data)