ExtensionDiscovery::scanDirectory

protected ExtensionDiscovery::scanDirectory($dir, $include_tests)

protected function scanDirectory($dir, $include_tests) {
  $files = array();

  // In order to scan top-level directories, absolute directory paths have to
  // be used (which also improves performance, since any configured PHP
  // include_paths will not be consulted). Retain the relative originating
  // directory being scanned, so relative paths can be reconstructed below
  // (all paths are expected to be relative to $this->root).
  $dir_prefix = ($dir == '' ? '' : "$dir/");
  $absolute_dir = ($dir == '' ? $this->root : $this->root . "/$dir");

  if (!is_dir($absolute_dir)) {
    return $files;
  }
  // Use Unix paths regardless of platform, skip dot directories, follow
  // symlinks (to allow extensions to be linked from elsewhere), and return
  // the RecursiveDirectoryIterator instance to have access to getSubPath(),
  // since SplFileInfo does not support relative paths.
  $flags = \FilesystemIterator::UNIX_PATHS;
  $flags |= \FilesystemIterator::SKIP_DOTS;
  $flags |= \FilesystemIterator::FOLLOW_SYMLINKS;
  $flags |= \FilesystemIterator::CURRENT_AS_SELF;
  $directory_iterator = new \RecursiveDirectoryIterator($absolute_dir, $flags);

  // Allow directories specified in settings.php to be ignored. You can use
  // this to not check for files in common special-purpose directories. For
  // example, node_modules and bower_components. Ignoring irrelevant
  // directories is a performance boost.
  $ignore_directories = Settings::get('file_scan_ignore_directories', []);

  // Filter the recursive scan to discover extensions only.
  // Important: Without a RecursiveFilterIterator, RecursiveDirectoryIterator
  // would recurse into the entire filesystem directory tree without any kind
  // of limitations.
  $filter = new RecursiveExtensionFilterIterator($directory_iterator, $ignore_directories);
  $filter->acceptTests($include_tests);

  // The actual recursive filesystem scan is only invoked by instantiating the
  // RecursiveIteratorIterator.
  $iterator = new \RecursiveIteratorIterator($filter, 
  \RecursiveIteratorIterator::LEAVES_ONLY, 
  // Suppress filesystem errors in case a directory cannot be accessed.
  \RecursiveIteratorIterator::CATCH_GET_CHILD
  );

  foreach ($iterator as $key => $fileinfo) {
    // All extension names in Drupal have to be valid PHP function names due
    // to the module hook architecture.
    if (!preg_match(static::PHP_FUNCTION_PATTERN, $fileinfo->getBasename('.info.yml'))) {
      continue;
    }

    if ($this->fileCache && $cached_extension = $this->fileCache->get($fileinfo->getPathName())) {
      $files[$cached_extension->getType()][$key] = $cached_extension;
      continue;
    }

    // Determine extension type from info file.
    $type = FALSE;
    $file = $fileinfo->openFile('r');
    while (!$type && !$file->eof()) {
      preg_match('@^type:\s*(\'|")?(\w+)\1?\s*$@', $file->fgets(), $matches);
      if (isset($matches[2])) {
        $type = $matches[2];
      }
    }
    if (empty($type)) {
      continue;
    }
    $name = $fileinfo->getBasename('.info.yml');
    $pathname = $dir_prefix . $fileinfo->getSubPathname();

    // Determine whether the extension has a main extension file.
    // For theme engines, the file extension is .engine.
    if ($type == 'theme_engine') {
      $filename = $name . '.engine';
    }
    // For profiles/modules/themes, it is the extension type.
    else {
      $filename = $name . '.' . $type;
    }
    if (!file_exists($this->root . '/' . dirname($pathname) . '/' . $filename)) {
      $filename = NULL;
    }

    $extension = new Extension($this->root, $type, $pathname, $filename);

    // Track the originating directory for sorting purposes.
    $extension->subpath = $fileinfo->getSubPath();
    $extension->origin = $dir;

    $files[$type][$key] = $extension;

    if ($this->fileCache) {
      $this->fileCache->set($fileinfo->getPathName(), $extension);
    }
  }
  return $files;
}