static interface Algorithm {
  S predict(int max);
  void feed(S s);
}

static class LuaAlgo implements Algorithm {
  LuaValue predict, feed;
  S feeding;
  
  *(S code) {
    Sandbox s = luaSandbox();
    evalLua(s, code);
    //print("KEYS: " + structure(s.keys()));
    predict = s.get("predict");
    if (predict.isnil()) predict = s.get("p");
    assertFalse(predict.isnil());
  }
  
  public S predict(int max) {
    LuaValue s = predict.call(Lua.value(max), feeding != null ? Lua.value(feeding) : Lua.NIL);
    feeding = null;
    ret s.isnil() ? "" : s.tojstring();
  }
  
  public void feed(S s) {
    feeding = s;
  }
}

static Algorithm makeLuaTextPredictAlgo(S desc) {
  ret new LuaAlgo(dropPrefix("L ", desc));
}