code: public Matcher getMatcher(String str) {
                  Matcher m;
                  if (matchers.containsKey(str)) {
                          m = matchers.get(str);
                  } else {
                          m = p.matcher(str);
                          matchers.put(str, m);
                  }
                  return m;
          }
docs: get matcher of the given string
  
  @param str string
  @return matcher