private String initSet(String line){
        Matcher m = P.matcher(line);
        if (m.find()) {
            do{
                String key = m.group(1);
                set.add(key);
                line = m.replaceFirst(key);
                engine.put(key, null);
            } while (m.reset(line).find());
        }
        System.out.println("  init set :" + set);
        return line;
    }