private function makeConstantStatements(): array
  {
    $width1    = 0;
    $width2    = 0;
    $constants = [];

    foreach ($this->constants as $constant => $value)
    {
      $width1 = max(mb_strlen($constant), $width1);
      $width2 = max(mb_strlen((string)$value), $width2);
    }

    $line_format = sprintf('  const %%-%ds = %%%dd;', $width1, $width2);
    foreach ($this->constants as $constant => $value)
    {
      $constants[] = sprintf($line_format, $constant, $value);
    }

    return $constants;
  }