getRegularExpression() public method

public getRegularExpression ( ) : string
return string the regular expression that determines the pattern used to validate a field.
 /**
  * @return string the regular expression that determines the pattern used to validate a field.
  */
 public function getRegularExpression()
 {
     $regex = parent::getRegularExpression();
     return $regex === '' ? self::EMAIL_REGEXP : $regex;
 }