sS ai_groupUsingProductions(S s, AI_BottomUpParser1 p) {
  p.splitSplittables = false;
  p.parse(javaTokNPunctuation(s));
  for (AI_BottomUpParser1.Word g : p.groups()) {
    int i = g.wordFrom*2+1, j = g.wordTo*2-1;
    if (endsWith(get(p.cnc, i), "{") && startsWith(get(p.cnc, j), "}"))
      continue;
    tokPrepend(p.cnc, i, "{");
    tokAppend(p.cnc, j, "}");
  }
  ret join(p.cnc);
}