class HelpTopicTwigLoader in Drupal 8

Loads help topic Twig files from the filesystem.

This loader adds module and theme help topic paths to a help_topics namespace to the Twig filesystem loader so that help_topics can be referenced, using '@help-topic/pluginId.html.twig'.

@internal Help Topics is currently experimental and should only be leveraged by experimental modules and development releases of contributed modules. See https://www.drupal.org/core/experimental for more information.

Hierarchy

• class \Drupal\help_topics\HelpTopicTwigLoader extends \Drupal\help_topics\Twig_Loader_Filesystem

See also

\Drupal\help_topics\HelpTopicDiscovery

\Drupal\help_topics\HelpTopicTwig

1 file declares its use of HelpTopicTwigLoader

HelpTopicTwigLoaderTest.php in core/modules/help_topics/tests/src/Unit/HelpTopicTwigLoaderTest.php

1 string reference to 'HelpTopicTwigLoader'

help_topics.services.yml in core/modules/help_topics/help_topics.services.yml

core/modules/help_topics/help_topics.services.yml

1 service uses HelpTopicTwigLoader

help.twig.loader in core/modules/help_topics/help_topics.services.yml

Drupal\help_topics\HelpTopicTwigLoader

File

core/modules/help_topics/src/HelpTopicTwigLoader.php, line 27

Namespace

Drupal\help_topics

class HelpTopicTwigLoader extends \Twig_Loader_Filesystem {

  /**
   * {@inheritdoc}
   */
  const MAIN_NAMESPACE = 'help_topics';

  /**
   * Constructs a new HelpTopicTwigLoader object.
   *
   * @param string $root_path
   *   The root path.
   * @param \Drupal\Core\Extension\ModuleHandlerInterface $module_handler
   *   The module handler service.
   * @param \Drupal\Core\Extension\ThemeHandlerInterface $theme_handler
   *   The theme handler service.
   */
  public function __construct($root_path, ModuleHandlerInterface $module_handler, ThemeHandlerInterface $theme_handler) {
    parent::__construct([], $root_path);

    // Add help_topics directories for modules and themes in the 'help_topic'
    // namespace, plus core.
    $this
      ->addExtension($root_path . '/core');
    array_map([
      $this,
      'addExtension',
    ], $module_handler
      ->getModuleDirectories());
    array_map([
      $this,
      'addExtension',
    ], $theme_handler
      ->getThemeDirectories());
  }

  /**
   * Adds an extensions help_topics directory to the Twig loader.
   *
   * @param $path
   *   The path to the extension.
   */
  protected function addExtension($path) {
    $path .= DIRECTORY_SEPARATOR . 'help_topics';
    if (is_dir($path)) {
      $this->cache = $this->errorCache = [];
      $this->paths[self::MAIN_NAMESPACE][] = rtrim($path, '/\\');
    }
  }

  /**
   * {@inheritdoc}
   */
  public function getSourceContext($name) {
    $path = $this
      ->findTemplate($name);
    $contents = file_get_contents($path);
    try {

      // Note: always use \Drupal\Core\Serialization\Yaml here instead of the
      // "serializer.yaml" service. This allows the core serializer to utilize
      // core related functionality which isn't available as the standalone
      // component based serializer.
      $front_matter = FrontMatter::load($contents, Yaml::class);

      // Reconstruct the content if there is front matter data detected. Prepend
      // the source with {% line \d+ %} to inform Twig that the source code
      // actually starts on a different line past the front matter data. This is
      // particularly useful when used in error reporting.
      if ($front_matter
        ->getData() && ($line = $front_matter
        ->getLine())) {
        $contents = "{% line {$line} %}" . $front_matter
          ->getCode();
      }
    } catch (InvalidDataTypeException $e) {
      throw new LoaderError(sprintf('Malformed YAML in help topic "%s": %s.', $path, $e
        ->getMessage()));
    }
    return new Source($contents, $name, $path);
  }

}

Members

Name	Modifiers	Type	Description	Overrides
HelpTopicTwigLoader::addExtension	protected	function	Adds an extensions help_topics directory to the Twig loader.
HelpTopicTwigLoader::getSourceContext	public	function
HelpTopicTwigLoader::MAIN_NAMESPACE		constant
HelpTopicTwigLoader::__construct	public	function	Constructs a new HelpTopicTwigLoader object.