camelCase to snake_case without separating numbers

camelCaseToSnakeCase.dart

String camelCaseToSnakeCase(String str) {
  final RegExp uppercases = RegExp('[A-Z]+');
  return str
    .replaceAllMapped(uppercases, (match) => ' ${match.group(0)}')
    .trim()
    .split(' ').map((s) => s.toLowerCase()).join('_');
}