private function findSourcesInPattern(string $pattern): array
  {
    $sources = [];

    $directory = new RecursiveDirectoryIterator(self::getLeadingDir($pattern));
    $directory->setFlags(RecursiveDirectoryIterator::FOLLOW_SYMLINKS);
    $files = new RecursiveIteratorIterator($directory);
    foreach ($files as $fullPath => $file)
    {
      // If the file is a source file with stored routine add it to my sources.
      if ($file->isFile() && SelectorHelper::matchPath($pattern, $fullPath))
      {
        $sources[] = $fullPath;
      }
    }

    return $sources;
  }