How do I split a String of nine characteres with a regular expression in Dart?

Question

I have a String called pin with a value like: 123456789 and I need to do the following:

What I have:

String pin = "123456789";

What I want after the operation:

String result = "123-456-789";

what I'm doing right now:

  String _formatReferenceCode(String code){
    final list = code.split("");
    String part1 = list.sublist(0, 3).join();
    String part2 = list.sublist(3, 6).join();
    String part3 = list.sublist(6, 9).join();
    return "$part1-$part2-$part3";
  }

String result = _formatReferenceCode(referenceCode);

// it prints: "123-456-789"

My current code works, but I want to know if there is a better way to do this. Thank you in advanced.

Solution

as an option you can use regexp negative lookahead

  String _formatReferenceCode(String code) {
    final Pattern pattern = RegExp(r'(.{3})(?!$)');
    return code.replaceAllMapped(pattern, (m) => '${m[0]}-');
  }

Comments

[BambinoUA]

As for me this regexp does not match the last 3 digits.

[BambinoUA]

Ok. I just tested the regular expression here regex101.com and I saw unexpected results.

[Pedro Massango]

This one seems the best option. Thank you @Eugene.