struct _xml_sort_hdl {
  XML * sort;
  XML * elem;
};
int _xml_sort_comparison (const void * a, const void * b);
XMLAPI XML * xml_sort (XML * list, XML * sort)
{
   int i;
   XML * child;
   struct _xml_sort_hdl * array;
   ELEMENTLIST * elist;

   /* Count the children. */
   i=0; child = xml_firstelem (list);
   while (child) {
      i++;
      child = xml_nextelem (child);
   }
   if (i < 2) return list;

   /* Build the array. */
   array = (struct _xml_sort_hdl *) malloc (i * sizeof (struct _xml_sort_hdl));
   i=0; child = xml_firstelem (list);
   while (child) {
      array[i].sort = sort;
      array[i].elem = child;
      i++;
      child = xml_nextelem (child);
   }

   /* Sort the array. */
   qsort (array, i, sizeof (struct _xml_sort_hdl), _xml_sort_comparison);

   /* Rearrange the children, being very slick about it. */
   i = 0; elist = list->children;
   while (elist) {
      if (elist->element->name) {
         elist->element = array[i].elem;
         i++;
      }
      elist = elist->next;
   }

   free ((void *) array);

   return list;
}

int _xml_sort_comparison (const void * a, const void * b)
{
   XML * sort;
   int res;
   int ia, ib;
   struct _xml_sort_hdl * _a = (struct _xml_sort_hdl *) a;
   struct _xml_sort_hdl * _b = (struct _xml_sort_hdl *) b;

   if (a == b) return 0;

   sort = _a->sort;
   while (sort) {
      if (!strcmp (xml_attrval (sort, "op"), "num")) {
         ia = xml_attrvalnum (_a->elem, xml_attrval (sort, "field"));
         ib = xml_attrvalnum (_b->elem, xml_attrval (sort, "field"));
         if (ia < ib) res = -1;
         if (ia > ib) res = 1;
      } else {
         res = strcmp (xml_attrval (_a->elem, xml_attrval (sort, "field")), xml_attrval (_b->elem, xml_attrval (sort, "field")));
      }

      if (!strcmp (xml_attrval (sort, "dir"), "desc")) res = - res;
      if (res) return res;

      sort = xml_firstelem (sort);
   }
   return 0;
}