@Override
public String convertToValang(String fieldName, Annotation a, MessageSourceAccessor messages) {
RegExp annotation = (RegExp) a;
String errMsg = messages.getMessage(annotation.errorCode(), annotation.message());
String applyIfValang = valangToJS(annotation.applyIf());
StringBuffer sb = new StringBuffer();
sb.append(" function() {return this.equals((this.RegExFunction(");
sb.append(wrapAndEscapeJsString(annotation.value())); // regex