static PTElement ai_parseBottomUpToTree_as(S input, S category) {
  final new AI_BottomUpParser1 parser;
  parser.parse(input);
  AI_BottomUpParser1.Word w = parser.fullGroup();
  if (w == null) null;
  if (!contains(w.classes, category)) null;
  ret ai_completeParseTree(parser, HaveCategory(w, category));
}