extractPossibleNumber static method

String extractPossibleNumber(String number)

Attempts to extract a possible number from the string passed in. This currently strips all leading characters that cannot be used to start a phone number. Characters that can be used to start a phone number are defined in the _validStartCharPattern. If none of these characters are found in the number passed in, an empty string is returned. This function also attempts to strip off any alternative extensions or endings if two or more are present, such as in the case of: [phone] x302/x2303. The second extension here makes this actually two phone numbers, [phone] x302 and [phone] x2303. We remove the second extension so that the first number is parsed correctly. number is the string that might contain a phone number. extractPossibleNumber returns the number, stripped of any non-phone-number prefix (such as 'Tel:') or an empty string if no character used to start phone numbers (such as + or any digit) is found in the number.

Implementation

static String extractPossibleNumber(String number) {
  RegExpMatch? m = _validStartCharPattern.firstMatch(number);
  if (m != null) {
    number = number.substring(m.start, number.length);
    // Remove trailing non-alpha non-numerical characters.
    RegExpMatch? trailingCharsMatcher =
        unwantedEndCharPattern.firstMatch(number);
    if (trailingCharsMatcher != null) {
      number = number.substring(0, trailingCharsMatcher.start);
    }
    // Check for extra numbers at the end.
    RegExpMatch? secondNumber = secondNumberStartPattern.firstMatch(number);
    if (secondNumber != null) {
      number = number.substring(0, secondNumber.start);
    }
    return number;
  } else {
    return '';
  }
}