WFTK_EXPORT XML * repos_get_layout (XML * repository, const char * layout_id)
{
   XML * ltop;
   XML * layout;
   XML * this_layout;
   XML * replace_layout;
   XML * layout_mark;
   const char * replaces;
   FILE * file;

   ltop = xml_loc (repository, ".layout");
   if (!ltop) {
      return NULL;
   }

   if (!layout_id) layout_id = xml_attrval (ltop, "default");
   if (!*layout_id) layout_id = xml_attrval (ltop, "default");

   if (!*layout_id) layout_id = xml_attrval (ltop, "id");
   if (!*layout_id) {
      layout_id = "top";
      xml_set (ltop, "id", "top");
   }

   this_layout = xml_locf (repository, ".cache.layout[%s]", layout_id);
   if (this_layout) {
      return (xml_copy (this_layout));
   }

   this_layout = xml_search (ltop, "layout", "id", layout_id);
   if (!this_layout) {
      return NULL;
   }

   layout = NULL;
   replace_layout = NULL;
   do {
      if (*xml_attrval (this_layout, "defn")) {
      file = _repos_fopen (repository, xml_attrval (this_layout, "defn"), "r");
         if (!file) {
            layout = xml_create ("layout-error");
            xml_setf (layout, "error", "Named layout definition file %s can't be opened.", xml_attrval (this_layout, "defn"));
            break;
         }
         layout = xml_parse_general (file, (XMLAPI_DATARETRIEVE) fread);
         fclose (file);
         if (xml_is (layout, "xml-error")) {
            xml_setf (layout, "error", "Named layout definition file %s is corrupt in line %s: [%s] %s\n", xml_attrval (this_layout, "defn"), xml_attrval (layout, "line"), xml_attrval (layout, "code"), xml_attrval (layout, "message"));
            break;
         }
      } else {
         layout = xml_copy (this_layout);
      }

      if (replace_layout) {
         layout_mark = xml_search (layout, "template:value", "id", replaces);
         if (!layout_mark) layout_mark = xml_search (layout, "template:value", "name", replaces);
         if (layout_mark) {
            xml_replacewithcontent (layout_mark, replace_layout);
         } else xml_free (replace_layout);
         replace_layout = NULL;
      }

      if (*xml_attrval (this_layout, "replace") && this_layout != ltop) {
         replace_layout = layout;
         replaces = xml_attrval (this_layout, "replace");
         layout = NULL;
         this_layout = xml_parent (this_layout);
      }
   } while (replace_layout);

   layout_mark = xml_loc (repository, ".cache");
   if (!layout_mark) {
      layout_mark = xml_create ("cache");
      xml_append (repository, layout_mark);
   }

   xml_set (layout, "id", layout_id);
   xml_append (layout_mark, layout);

   return (xml_copy (layout));
}