persistable srecord RegExp(S pattern, bool caseInsensitive) {
  transient Pattern compiled;
  S error;
  
  *(S *pattern) {}

  // TODO: don't compile again when error detected?
  java.util.regex.Pattern compile aka get() {
    try {
      compiled if null = compileRegexpPossiblyIC(pattern, caseInsensitive);
      error = null;
      ret compiled;
    } catch e {
      error = exceptionToStringShort(e);
      null;
    }
  }
  
  bool valid() {
    ret compile() != null;
  }
  
  bool containsSpecialChars() {
    ret containsRegExpSpecialChars(pattern);
  }
  
  bool containedIn(S s) {
    ret regexpContains(getForce(), s);
  }
  
  java.util.regex.Pattern getForce() {
    var pattern = get();
    if (error != null) fail(error, pattern);
    ret pattern;
  }
}