camelToTitle function

Implementation

String camelToTitle(String input) {
  if (input.isEmpty) return input;

  // Split on boundaries: a) lower/digit -> Upper, b) ACRONYM -> Word,
  // c) letter <-> digit. Also handle stray '_' or '-' just in case.
  final words = input
      .replaceAll(RegExp(r'[_\-]+'), ' ')
      .split(
        RegExp(
          r'(?<=[a-z0-9])(?=[A-Z])' // fooBar
          r'|(?<=[A-Z])(?=[A-Z][a-z])' // HTTPResponse
          r'|(?<=[A-Za-z])(?=[0-9])' // value2
          r'|(?<=[0-9])(?=[A-Za-z])', // 2value
        ),
      )
      .expand((w) => w.split(' '))
      .where((w) => w.isNotEmpty)
      .toList();

  String toWord(String s) {
    final isAcronym = s.length > 1 && !s.contains(RegExp(r'[a-z]'));
    return isAcronym ? s : s[0].toUpperCase() + s.substring(1).toLowerCase();
  }

  return words.map(toWord).join(' ');
}