Chris@0: <?php
Chris@0: 
Chris@0: namespace Drupal\Core\Render;
Chris@0: 
Chris@0: use Drupal\Component\Render\MarkupInterface;
Chris@0: use Drupal\Component\Utility\Html;
Chris@0: use Drupal\Component\Utility\Xss;
Chris@0: use Drupal\Core\Access\AccessResultInterface;
Chris@0: use Drupal\Core\Cache\Cache;
Chris@0: use Drupal\Core\Cache\CacheableMetadata;
Chris@0: use Drupal\Core\Controller\ControllerResolverInterface;
Chris@0: use Drupal\Core\Theme\ThemeManagerInterface;
Chris@0: use Symfony\Component\HttpFoundation\RequestStack;
Chris@0: 
Chris@0: /**
Chris@0:  * Turns a render array into a HTML string.
Chris@0:  */
Chris@0: class Renderer implements RendererInterface {
Chris@0: 
Chris@0:   /**
Chris@0:    * The theme manager.
Chris@0:    *
Chris@0:    * @var \Drupal\Core\Theme\ThemeManagerInterface
Chris@0:    */
Chris@0:   protected $theme;
Chris@0: 
Chris@0:   /**
Chris@0:    * The controller resolver.
Chris@0:    *
Chris@0:    * @var \Drupal\Core\Controller\ControllerResolverInterface
Chris@0:    */
Chris@0:   protected $controllerResolver;
Chris@0: 
Chris@0:   /**
Chris@0:    * The element info.
Chris@0:    *
Chris@0:    * @var \Drupal\Core\Render\ElementInfoManagerInterface
Chris@0:    */
Chris@0:   protected $elementInfo;
Chris@0: 
Chris@0:   /**
Chris@0:    * The placeholder generator.
Chris@0:    *
Chris@0:    * @var \Drupal\Core\Render\PlaceholderGeneratorInterface
Chris@0:    */
Chris@0:   protected $placeholderGenerator;
Chris@0: 
Chris@0:   /**
Chris@0:    * The render cache service.
Chris@0:    *
Chris@0:    * @var \Drupal\Core\Render\RenderCacheInterface
Chris@0:    */
Chris@0:   protected $renderCache;
Chris@0: 
Chris@0:   /**
Chris@0:    * The renderer configuration array.
Chris@0:    *
Chris@0:    * @var array
Chris@0:    */
Chris@0:   protected $rendererConfig;
Chris@0: 
Chris@0:   /**
Chris@0:    * Whether we're currently in a ::renderRoot() call.
Chris@0:    *
Chris@0:    * @var bool
Chris@0:    */
Chris@0:   protected $isRenderingRoot = FALSE;
Chris@0: 
Chris@0:   /**
Chris@0:    * The request stack.
Chris@0:    *
Chris@0:    * @var \Symfony\Component\HttpFoundation\RequestStack
Chris@0:    */
Chris@0:   protected $requestStack;
Chris@0: 
Chris@0:   /**
Chris@0:    * The render context collection.
Chris@0:    *
Chris@0:    * An individual global render context is tied to the current request. We then
Chris@0:    * need to maintain a different context for each request to correctly handle
Chris@0:    * rendering in subrequests.
Chris@0:    *
Chris@0:    * This must be static as long as some controllers rebuild the container
Chris@0:    * during a request. This causes multiple renderer instances to co-exist
Chris@0:    * simultaneously, render state getting lost, and therefore causing pages to
Chris@0:    * fail to render correctly. As soon as it is guaranteed that during a request
Chris@0:    * the same container is used, it no longer needs to be static.
Chris@0:    *
Chris@0:    * @var \Drupal\Core\Render\RenderContext[]
Chris@0:    */
Chris@0:   protected static $contextCollection;
Chris@0: 
Chris@0:   /**
Chris@0:    * Constructs a new Renderer.
Chris@0:    *
Chris@0:    * @param \Drupal\Core\Controller\ControllerResolverInterface $controller_resolver
Chris@0:    *   The controller resolver.
Chris@0:    * @param \Drupal\Core\Theme\ThemeManagerInterface $theme
Chris@0:    *   The theme manager.
Chris@0:    * @param \Drupal\Core\Render\ElementInfoManagerInterface $element_info
Chris@0:    *   The element info.
Chris@0:    * @param \Drupal\Core\Render\PlaceholderGeneratorInterface $placeholder_generator
Chris@0:    *   The placeholder generator.
Chris@0:    * @param \Drupal\Core\Render\RenderCacheInterface $render_cache
Chris@0:    *   The render cache service.
Chris@0:    * @param \Symfony\Component\HttpFoundation\RequestStack $request_stack
Chris@0:    *   The request stack.
Chris@0:    * @param array $renderer_config
Chris@0:    *   The renderer configuration array.
Chris@0:    */
Chris@0:   public function __construct(ControllerResolverInterface $controller_resolver, ThemeManagerInterface $theme, ElementInfoManagerInterface $element_info, PlaceholderGeneratorInterface $placeholder_generator, RenderCacheInterface $render_cache, RequestStack $request_stack, array $renderer_config) {
Chris@0:     $this->controllerResolver = $controller_resolver;
Chris@0:     $this->theme = $theme;
Chris@0:     $this->elementInfo = $element_info;
Chris@0:     $this->placeholderGenerator = $placeholder_generator;
Chris@0:     $this->renderCache = $render_cache;
Chris@0:     $this->rendererConfig = $renderer_config;
Chris@0:     $this->requestStack = $request_stack;
Chris@0: 
Chris@0:     // Initialize the context collection if needed.
Chris@0:     if (!isset(static::$contextCollection)) {
Chris@0:       static::$contextCollection = new \SplObjectStorage();
Chris@0:     }
Chris@0:   }
Chris@0: 
Chris@0:   /**
Chris@0:    * {@inheritdoc}
Chris@0:    */
Chris@0:   public function renderRoot(&$elements) {
Chris@0:     // Disallow calling ::renderRoot() from within another ::renderRoot() call.
Chris@0:     if ($this->isRenderingRoot) {
Chris@0:       $this->isRenderingRoot = FALSE;
Chris@0:       throw new \LogicException('A stray renderRoot() invocation is causing bubbling of attached assets to break.');
Chris@0:     }
Chris@0: 
Chris@0:     // Render in its own render context.
Chris@0:     $this->isRenderingRoot = TRUE;
Chris@0:     $output = $this->executeInRenderContext(new RenderContext(), function () use (&$elements) {
Chris@0:       return $this->render($elements, TRUE);
Chris@0:     });
Chris@0:     $this->isRenderingRoot = FALSE;
Chris@0: 
Chris@0:     return $output;
Chris@0:   }
Chris@0: 
Chris@0:   /**
Chris@0:    * {@inheritdoc}
Chris@0:    */
Chris@0:   public function renderPlain(&$elements) {
Chris@0:     return $this->executeInRenderContext(new RenderContext(), function () use (&$elements) {
Chris@0:       return $this->render($elements, TRUE);
Chris@0:     });
Chris@0:   }
Chris@0: 
Chris@0:   /**
Chris@0:    * {@inheritdoc}
Chris@0:    */
Chris@0:   public function renderPlaceholder($placeholder, array $elements) {
Chris@0:     // Get the render array for the given placeholder
Chris@0:     $placeholder_elements = $elements['#attached']['placeholders'][$placeholder];
Chris@0: 
Chris@0:     // Prevent the render array from being auto-placeholdered again.
Chris@0:     $placeholder_elements['#create_placeholder'] = FALSE;
Chris@0: 
Chris@0:     // Render the placeholder into markup.
Chris@0:     $markup = $this->renderPlain($placeholder_elements);
Chris@0: 
Chris@0:     // Replace the placeholder with its rendered markup, and merge its
Chris@0:     // bubbleable metadata with the main elements'.
Chris@0:     $elements['#markup'] = Markup::create(str_replace($placeholder, $markup, $elements['#markup']));
Chris@0:     $elements = $this->mergeBubbleableMetadata($elements, $placeholder_elements);
Chris@0: 
Chris@0:     // Remove the placeholder that we've just rendered.
Chris@0:     unset($elements['#attached']['placeholders'][$placeholder]);
Chris@0: 
Chris@0:     return $elements;
Chris@0:   }
Chris@0: 
Chris@0:   /**
Chris@0:    * {@inheritdoc}
Chris@0:    */
Chris@0:   public function render(&$elements, $is_root_call = FALSE) {
Chris@0:     // Since #pre_render, #post_render, #lazy_builder callbacks and theme
Chris@0:     // functions or templates may be used for generating a render array's
Chris@0:     // content, and we might be rendering the main content for the page, it is
Chris@0:     // possible that any of them throw an exception that will cause a different
Chris@0:     // page to be rendered (e.g. throwing
Chris@0:     // \Symfony\Component\HttpKernel\Exception\NotFoundHttpException will cause
Chris@0:     // the 404 page to be rendered). That page might also use
Chris@0:     // Renderer::renderRoot() but if exceptions aren't caught here, it will be
Chris@0:     // impossible to call Renderer::renderRoot() again.
Chris@0:     // Hence, catch all exceptions, reset the isRenderingRoot property and
Chris@0:     // re-throw exceptions.
Chris@0:     try {
Chris@0:       return $this->doRender($elements, $is_root_call);
Chris@0:     }
Chris@0:     catch (\Exception $e) {
Chris@0:       // Mark the ::rootRender() call finished due to this exception & re-throw.
Chris@0:       $this->isRenderingRoot = FALSE;
Chris@0:       throw $e;
Chris@0:     }
Chris@0:   }
Chris@0: 
Chris@0:   /**
Chris@0:    * See the docs for ::render().
Chris@0:    */
Chris@0:   protected function doRender(&$elements, $is_root_call = FALSE) {
Chris@0:     if (empty($elements)) {
Chris@0:       return '';
Chris@0:     }
Chris@0: 
Chris@0:     if (!isset($elements['#access']) && isset($elements['#access_callback'])) {
Chris@0:       if (is_string($elements['#access_callback']) && strpos($elements['#access_callback'], '::') === FALSE) {
Chris@0:         $elements['#access_callback'] = $this->controllerResolver->getControllerFromDefinition($elements['#access_callback']);
Chris@0:       }
Chris@0:       $elements['#access'] = call_user_func($elements['#access_callback'], $elements);
Chris@0:     }
Chris@0: 
Chris@0:     // Early-return nothing if user does not have access.
Chris@0:     if (isset($elements['#access'])) {
Chris@14:       // If #access is an AccessResultInterface object, we must apply its
Chris@0:       // cacheability metadata to the render array.
Chris@0:       if ($elements['#access'] instanceof AccessResultInterface) {
Chris@0:         $this->addCacheableDependency($elements, $elements['#access']);
Chris@0:         if (!$elements['#access']->isAllowed()) {
Chris@0:           return '';
Chris@0:         }
Chris@0:       }
Chris@0:       elseif ($elements['#access'] === FALSE) {
Chris@0:         return '';
Chris@0:       }
Chris@0:     }
Chris@0: 
Chris@0:     // Do not print elements twice.
Chris@0:     if (!empty($elements['#printed'])) {
Chris@0:       return '';
Chris@0:     }
Chris@0: 
Chris@0:     $context = $this->getCurrentRenderContext();
Chris@0:     if (!isset($context)) {
Chris@0:       throw new \LogicException("Render context is empty, because render() was called outside of a renderRoot() or renderPlain() call. Use renderPlain()/renderRoot() or #lazy_builder/#pre_render instead.");
Chris@0:     }
Chris@0:     $context->push(new BubbleableMetadata());
Chris@0: 
Chris@0:     // Set the bubbleable rendering metadata that has configurable defaults, if:
Chris@0:     // - this is the root call, to ensure that the final render array definitely
Chris@0:     //   has these configurable defaults, even when no subtree is render cached.
Chris@0:     // - this is a render cacheable subtree, to ensure that the cached data has
Chris@0:     //   the configurable defaults (which may affect the ID and invalidation).
Chris@0:     if ($is_root_call || isset($elements['#cache']['keys'])) {
Chris@0:       $required_cache_contexts = $this->rendererConfig['required_cache_contexts'];
Chris@0:       if (isset($elements['#cache']['contexts'])) {
Chris@0:         $elements['#cache']['contexts'] = Cache::mergeContexts($elements['#cache']['contexts'], $required_cache_contexts);
Chris@0:       }
Chris@0:       else {
Chris@0:         $elements['#cache']['contexts'] = $required_cache_contexts;
Chris@0:       }
Chris@0:     }
Chris@0: 
Chris@0:     // Try to fetch the prerendered element from cache, replace any placeholders
Chris@0:     // and return the final markup.
Chris@0:     if (isset($elements['#cache']['keys'])) {
Chris@0:       $cached_element = $this->renderCache->get($elements);
Chris@0:       if ($cached_element !== FALSE) {
Chris@0:         $elements = $cached_element;
Chris@0:         // Only when we're in a root (non-recursive) Renderer::render() call,
Chris@0:         // placeholders must be processed, to prevent breaking the render cache
Chris@0:         // in case of nested elements with #cache set.
Chris@0:         if ($is_root_call) {
Chris@0:           $this->replacePlaceholders($elements);
Chris@0:         }
Chris@0:         // Mark the element markup as safe if is it a string.
Chris@0:         if (is_string($elements['#markup'])) {
Chris@0:           $elements['#markup'] = Markup::create($elements['#markup']);
Chris@0:         }
Chris@0:         // The render cache item contains all the bubbleable rendering metadata
Chris@0:         // for the subtree.
Chris@0:         $context->update($elements);
Chris@0:         // Render cache hit, so rendering is finished, all necessary info
Chris@0:         // collected!
Chris@0:         $context->bubble();
Chris@0:         return $elements['#markup'];
Chris@0:       }
Chris@0:     }
Chris@0:     // Two-tier caching: track pre-bubbling elements' #cache, #lazy_builder and
Chris@0:     // #create_placeholder for later comparison.
Chris@0:     // @see \Drupal\Core\Render\RenderCacheInterface::get()
Chris@0:     // @see \Drupal\Core\Render\RenderCacheInterface::set()
Chris@0:     $pre_bubbling_elements = array_intersect_key($elements, [
Chris@0:       '#cache' => TRUE,
Chris@0:       '#lazy_builder' => TRUE,
Chris@0:       '#create_placeholder' => TRUE,
Chris@0:     ]);
Chris@0: 
Chris@0:     // If the default values for this element have not been loaded yet, populate
Chris@0:     // them.
Chris@0:     if (isset($elements['#type']) && empty($elements['#defaults_loaded'])) {
Chris@0:       $elements += $this->elementInfo->getInfo($elements['#type']);
Chris@0:     }
Chris@0: 
Chris@0:     // First validate the usage of #lazy_builder; both of the next if-statements
Chris@0:     // use it if available.
Chris@0:     if (isset($elements['#lazy_builder'])) {
Chris@0:       // @todo Convert to assertions once https://www.drupal.org/node/2408013
Chris@0:       //   lands.
Chris@0:       if (!is_array($elements['#lazy_builder'])) {
Chris@0:         throw new \DomainException('The #lazy_builder property must have an array as a value.');
Chris@0:       }
Chris@0:       if (count($elements['#lazy_builder']) !== 2) {
Chris@0:         throw new \DomainException('The #lazy_builder property must have an array as a value, containing two values: the callback, and the arguments for the callback.');
Chris@0:       }
Chris@0:       if (count($elements['#lazy_builder'][1]) !== count(array_filter($elements['#lazy_builder'][1], function ($v) {
Chris@0:         return is_null($v) || is_scalar($v);
Chris@0:       }))) {
Chris@0:         throw new \DomainException("A #lazy_builder callback's context may only contain scalar values or NULL.");
Chris@0:       }
Chris@0:       $children = Element::children($elements);
Chris@0:       if ($children) {
Chris@0:         throw new \DomainException(sprintf('When a #lazy_builder callback is specified, no children can exist; all children must be generated by the #lazy_builder callback. You specified the following children: %s.', implode(', ', $children)));
Chris@0:       }
Chris@0:       $supported_keys = [
Chris@0:         '#lazy_builder',
Chris@0:         '#cache',
Chris@0:         '#create_placeholder',
Chris@0:         // The keys below are not actually supported, but these are added
Chris@0:         // automatically by the Renderer. Adding them as though they are
Chris@0:         // supported allows us to avoid throwing an exception 100% of the time.
Chris@0:         '#weight',
Chris@17:         '#printed',
Chris@0:       ];
Chris@0:       $unsupported_keys = array_diff(array_keys($elements), $supported_keys);
Chris@0:       if (count($unsupported_keys)) {
Chris@0:         throw new \DomainException(sprintf('When a #lazy_builder callback is specified, no properties can exist; all properties must be generated by the #lazy_builder callback. You specified the following properties: %s.', implode(', ', $unsupported_keys)));
Chris@0:       }
Chris@0:     }
Chris@0:     // Determine whether to do auto-placeholdering.
Chris@0:     if ($this->placeholderGenerator->canCreatePlaceholder($elements) && $this->placeholderGenerator->shouldAutomaticallyPlaceholder($elements)) {
Chris@0:       $elements['#create_placeholder'] = TRUE;
Chris@0:     }
Chris@0:     // If instructed to create a placeholder, and a #lazy_builder callback is
Chris@0:     // present (without such a callback, it would be impossible to replace the
Chris@0:     // placeholder), replace the current element with a placeholder.
Chris@0:     // @todo remove the isMethodCacheable() check when
Chris@0:     //       https://www.drupal.org/node/2367555 lands.
Chris@0:     if (isset($elements['#create_placeholder']) && $elements['#create_placeholder'] === TRUE && $this->requestStack->getCurrentRequest()->isMethodCacheable()) {
Chris@0:       if (!isset($elements['#lazy_builder'])) {
Chris@0:         throw new \LogicException('When #create_placeholder is set, a #lazy_builder callback must be present as well.');
Chris@0:       }
Chris@0:       $elements = $this->placeholderGenerator->createPlaceholder($elements);
Chris@0:     }
Chris@0:     // Build the element if it is still empty.
Chris@0:     if (isset($elements['#lazy_builder'])) {
Chris@0:       $callable = $elements['#lazy_builder'][0];
Chris@0:       $args = $elements['#lazy_builder'][1];
Chris@0:       if (is_string($callable) && strpos($callable, '::') === FALSE) {
Chris@0:         $callable = $this->controllerResolver->getControllerFromDefinition($callable);
Chris@0:       }
Chris@0:       $new_elements = call_user_func_array($callable, $args);
Chris@0:       // Retain the original cacheability metadata, plus cache keys.
Chris@0:       CacheableMetadata::createFromRenderArray($elements)
Chris@0:         ->merge(CacheableMetadata::createFromRenderArray($new_elements))
Chris@0:         ->applyTo($new_elements);
Chris@0:       if (isset($elements['#cache']['keys'])) {
Chris@0:         $new_elements['#cache']['keys'] = $elements['#cache']['keys'];
Chris@0:       }
Chris@0:       $elements = $new_elements;
Chris@0:       $elements['#lazy_builder_built'] = TRUE;
Chris@0:     }
Chris@0: 
Chris@0:     // Make any final changes to the element before it is rendered. This means
Chris@0:     // that the $element or the children can be altered or corrected before the
Chris@0:     // element is rendered into the final text.
Chris@0:     if (isset($elements['#pre_render'])) {
Chris@0:       foreach ($elements['#pre_render'] as $callable) {
Chris@0:         if (is_string($callable) && strpos($callable, '::') === FALSE) {
Chris@0:           $callable = $this->controllerResolver->getControllerFromDefinition($callable);
Chris@0:         }
Chris@0:         $elements = call_user_func($callable, $elements);
Chris@0:       }
Chris@0:     }
Chris@0: 
Chris@0:     // All render elements support #markup and #plain_text.
Chris@16:     if (isset($elements['#markup']) || isset($elements['#plain_text'])) {
Chris@0:       $elements = $this->ensureMarkupIsSafe($elements);
Chris@0:     }
Chris@0: 
Chris@0:     // Defaults for bubbleable rendering metadata.
Chris@0:     $elements['#cache']['tags'] = isset($elements['#cache']['tags']) ? $elements['#cache']['tags'] : [];
Chris@0:     $elements['#cache']['max-age'] = isset($elements['#cache']['max-age']) ? $elements['#cache']['max-age'] : Cache::PERMANENT;
Chris@0:     $elements['#attached'] = isset($elements['#attached']) ? $elements['#attached'] : [];
Chris@0: 
Chris@0:     // Allow #pre_render to abort rendering.
Chris@0:     if (!empty($elements['#printed'])) {
Chris@0:       // The #printed element contains all the bubbleable rendering metadata for
Chris@0:       // the subtree.
Chris@0:       $context->update($elements);
Chris@0:       // #printed, so rendering is finished, all necessary info collected!
Chris@0:       $context->bubble();
Chris@0:       return '';
Chris@0:     }
Chris@0: 
Chris@0:     // Add any JavaScript state information associated with the element.
Chris@0:     if (!empty($elements['#states'])) {
Chris@0:       drupal_process_states($elements);
Chris@0:     }
Chris@0: 
Chris@0:     // Get the children of the element, sorted by weight.
Chris@0:     $children = Element::children($elements, TRUE);
Chris@0: 
Chris@0:     // Initialize this element's #children, unless a #pre_render callback
Chris@0:     // already preset #children.
Chris@0:     if (!isset($elements['#children'])) {
Chris@0:       $elements['#children'] = '';
Chris@0:     }
Chris@0: 
Chris@0:     // Assume that if #theme is set it represents an implemented hook.
Chris@0:     $theme_is_implemented = isset($elements['#theme']);
Chris@0:     // Check the elements for insecure HTML and pass through sanitization.
Chris@0:     if (isset($elements)) {
Chris@0:       $markup_keys = [
Chris@0:         '#description',
Chris@0:         '#field_prefix',
Chris@0:         '#field_suffix',
Chris@0:       ];
Chris@0:       foreach ($markup_keys as $key) {
Chris@0:         if (!empty($elements[$key]) && is_scalar($elements[$key])) {
Chris@0:           $elements[$key] = $this->xssFilterAdminIfUnsafe($elements[$key]);
Chris@0:         }
Chris@0:       }
Chris@0:     }
Chris@0: 
Chris@0:     // Call the element's #theme function if it is set. Then any children of the
Chris@0:     // element have to be rendered there. If the internal #render_children
Chris@0:     // property is set, do not call the #theme function to prevent infinite
Chris@0:     // recursion.
Chris@0:     if ($theme_is_implemented && !isset($elements['#render_children'])) {
Chris@0:       $elements['#children'] = $this->theme->render($elements['#theme'], $elements);
Chris@0: 
Chris@0:       // If ThemeManagerInterface::render() returns FALSE this means that the
Chris@0:       // hook in #theme was not found in the registry and so we need to update
Chris@0:       // our flag accordingly. This is common for theme suggestions.
Chris@0:       $theme_is_implemented = ($elements['#children'] !== FALSE);
Chris@0:     }
Chris@0: 
Chris@0:     // If #theme is not implemented or #render_children is set and the element
Chris@0:     // has an empty #children attribute, render the children now. This is the
Chris@0:     // same process as Renderer::render() but is inlined for speed.
Chris@0:     if ((!$theme_is_implemented || isset($elements['#render_children'])) && empty($elements['#children'])) {
Chris@0:       foreach ($children as $key) {
Chris@0:         $elements['#children'] .= $this->doRender($elements[$key]);
Chris@0:       }
Chris@0:       $elements['#children'] = Markup::create($elements['#children']);
Chris@0:     }
Chris@0: 
Chris@0:     // If #theme is not implemented and the element has raw #markup as a
Chris@0:     // fallback, prepend the content in #markup to #children. In this case
Chris@0:     // #children will contain whatever is provided by #pre_render prepended to
Chris@0:     // what is rendered recursively above. If #theme is implemented then it is
Chris@0:     // the responsibility of that theme implementation to render #markup if
Chris@0:     // required. Eventually #theme_wrappers will expect both #markup and
Chris@0:     // #children to be a single string as #children.
Chris@0:     if (!$theme_is_implemented && isset($elements['#markup'])) {
Chris@0:       $elements['#children'] = Markup::create($elements['#markup'] . $elements['#children']);
Chris@0:     }
Chris@0: 
Chris@0:     // Let the theme functions in #theme_wrappers add markup around the rendered
Chris@0:     // children.
Chris@0:     // #states and #attached have to be processed before #theme_wrappers,
Chris@0:     // because the #type 'page' render array from drupal_prepare_page() would
Chris@0:     // render the $page and wrap it into the html.html.twig template without the
Chris@0:     // attached assets otherwise.
Chris@0:     // If the internal #render_children property is set, do not call the
Chris@0:     // #theme_wrappers function(s) to prevent infinite recursion.
Chris@0:     if (isset($elements['#theme_wrappers']) && !isset($elements['#render_children'])) {
Chris@0:       foreach ($elements['#theme_wrappers'] as $key => $value) {
Chris@0:         // If the value of a #theme_wrappers item is an array then the theme
Chris@0:         // hook is found in the key of the item and the value contains attribute
Chris@0:         // overrides. Attribute overrides replace key/value pairs in $elements
Chris@0:         // for only this ThemeManagerInterface::render() call. This allows
Chris@0:         // #theme hooks and #theme_wrappers hooks to share variable names
Chris@0:         // without conflict or ambiguity.
Chris@0:         $wrapper_elements = $elements;
Chris@0:         if (is_string($key)) {
Chris@0:           $wrapper_hook = $key;
Chris@0:           foreach ($value as $attribute => $override) {
Chris@0:             $wrapper_elements[$attribute] = $override;
Chris@0:           }
Chris@0:         }
Chris@0:         else {
Chris@0:           $wrapper_hook = $value;
Chris@0:         }
Chris@0: 
Chris@0:         $elements['#children'] = $this->theme->render($wrapper_hook, $wrapper_elements);
Chris@0:       }
Chris@0:     }
Chris@0: 
Chris@0:     // Filter the outputted content and make any last changes before the content
Chris@0:     // is sent to the browser. The changes are made on $content which allows the
Chris@0:     // outputted text to be filtered.
Chris@0:     if (isset($elements['#post_render'])) {
Chris@0:       foreach ($elements['#post_render'] as $callable) {
Chris@0:         if (is_string($callable) && strpos($callable, '::') === FALSE) {
Chris@0:           $callable = $this->controllerResolver->getControllerFromDefinition($callable);
Chris@0:         }
Chris@0:         $elements['#children'] = call_user_func($callable, $elements['#children'], $elements);
Chris@0:       }
Chris@0:     }
Chris@0: 
Chris@0:     // We store the resulting output in $elements['#markup'], to be consistent
Chris@0:     // with how render cached output gets stored. This ensures that placeholder
Chris@0:     // replacement logic gets the same data to work with, no matter if #cache is
Chris@12:     // disabled, #cache is enabled, there is a cache hit or miss. If
Chris@12:     // #render_children is set the #prefix and #suffix will have already been
Chris@12:     // added.
Chris@12:     if (isset($elements['#render_children'])) {
Chris@12:       $elements['#markup'] = Markup::create($elements['#children']);
Chris@12:     }
Chris@12:     else {
Chris@12:       $prefix = isset($elements['#prefix']) ? $this->xssFilterAdminIfUnsafe($elements['#prefix']) : '';
Chris@12:       $suffix = isset($elements['#suffix']) ? $this->xssFilterAdminIfUnsafe($elements['#suffix']) : '';
Chris@12:       $elements['#markup'] = Markup::create($prefix . $elements['#children'] . $suffix);
Chris@12:     }
Chris@0: 
Chris@0:     // We've rendered this element (and its subtree!), now update the context.
Chris@0:     $context->update($elements);
Chris@0: 
Chris@0:     // Cache the processed element if both $pre_bubbling_elements and $elements
Chris@0:     // have the metadata necessary to generate a cache ID.
Chris@0:     if (isset($pre_bubbling_elements['#cache']['keys']) && isset($elements['#cache']['keys'])) {
Chris@0:       if ($pre_bubbling_elements['#cache']['keys'] !== $elements['#cache']['keys']) {
Chris@0:         throw new \LogicException('Cache keys may not be changed after initial setup. Use the contexts property instead to bubble additional metadata.');
Chris@0:       }
Chris@0:       $this->renderCache->set($elements, $pre_bubbling_elements);
Chris@0:       // Update the render context; the render cache implementation may update
Chris@0:       // the element, and it may have different bubbleable metadata now.
Chris@0:       // @see \Drupal\Core\Render\PlaceholderingRenderCache::set()
Chris@0:       $context->pop();
Chris@0:       $context->push(new BubbleableMetadata());
Chris@0:       $context->update($elements);
Chris@0:     }
Chris@0: 
Chris@0:     // Only when we're in a root (non-recursive) Renderer::render() call,
Chris@0:     // placeholders must be processed, to prevent breaking the render cache in
Chris@0:     // case of nested elements with #cache set.
Chris@0:     //
Chris@0:     // By running them here, we ensure that:
Chris@0:     // - they run when #cache is disabled,
Chris@0:     // - they run when #cache is enabled and there is a cache miss.
Chris@0:     // Only the case of a cache hit when #cache is enabled, is not handled here,
Chris@0:     // that is handled earlier in Renderer::render().
Chris@0:     if ($is_root_call) {
Chris@0:       $this->replacePlaceholders($elements);
Chris@0:       // @todo remove as part of https://www.drupal.org/node/2511330.
Chris@0:       if ($context->count() !== 1) {
Chris@0:         throw new \LogicException('A stray drupal_render() invocation with $is_root_call = TRUE is causing bubbling of attached assets to break.');
Chris@0:       }
Chris@0:     }
Chris@0: 
Chris@0:     // Rendering is finished, all necessary info collected!
Chris@0:     $context->bubble();
Chris@0: 
Chris@0:     $elements['#printed'] = TRUE;
Chris@0:     return $elements['#markup'];
Chris@0:   }
Chris@0: 
Chris@0:   /**
Chris@0:    * {@inheritdoc}
Chris@0:    */
Chris@0:   public function hasRenderContext() {
Chris@0:     return (bool) $this->getCurrentRenderContext();
Chris@0:   }
Chris@0: 
Chris@0:   /**
Chris@0:    * {@inheritdoc}
Chris@0:    */
Chris@0:   public function executeInRenderContext(RenderContext $context, callable $callable) {
Chris@0:     // Store the current render context.
Chris@0:     $previous_context = $this->getCurrentRenderContext();
Chris@0: 
Chris@0:     // Set the provided context and call the callable, it will use that context.
Chris@0:     $this->setCurrentRenderContext($context);
Chris@0:     $result = $callable();
Chris@0:     // @todo Convert to an assertion in https://www.drupal.org/node/2408013
Chris@0:     if ($context->count() > 1) {
Chris@0:       throw new \LogicException('Bubbling failed.');
Chris@0:     }
Chris@0: 
Chris@0:     // Restore the original render context.
Chris@0:     $this->setCurrentRenderContext($previous_context);
Chris@0: 
Chris@0:     return $result;
Chris@0:   }
Chris@0: 
Chris@0:   /**
Chris@0:    * Returns the current render context.
Chris@0:    *
Chris@0:    * @return \Drupal\Core\Render\RenderContext
Chris@0:    *   The current render context.
Chris@0:    */
Chris@0:   protected function getCurrentRenderContext() {
Chris@0:     $request = $this->requestStack->getCurrentRequest();
Chris@0:     return isset(static::$contextCollection[$request]) ? static::$contextCollection[$request] : NULL;
Chris@0:   }
Chris@0: 
Chris@0:   /**
Chris@0:    * Sets the current render context.
Chris@0:    *
Chris@0:    * @param \Drupal\Core\Render\RenderContext|null $context
Chris@0:    *   The render context. This can be NULL for instance when restoring the
Chris@0:    *   original render context, which is in fact NULL.
Chris@0:    *
Chris@0:    * @return $this
Chris@0:    */
Chris@0:   protected function setCurrentRenderContext(RenderContext $context = NULL) {
Chris@0:     $request = $this->requestStack->getCurrentRequest();
Chris@0:     static::$contextCollection[$request] = $context;
Chris@0:     return $this;
Chris@0:   }
Chris@0: 
Chris@0:   /**
Chris@0:    * Replaces placeholders.
Chris@0:    *
Chris@0:    * Placeholders may have:
Chris@0:    * - #lazy_builder callback, to build a render array to be rendered into
Chris@0:    *   markup that can replace the placeholder
Chris@0:    * - #cache: to cache the result of the placeholder
Chris@0:    *
Chris@0:    * Also merges the bubbleable metadata resulting from the rendering of the
Chris@0:    * contents of the placeholders. Hence $elements will be contain the entirety
Chris@0:    * of bubbleable metadata.
Chris@0:    *
Chris@0:    * @param array &$elements
Chris@0:    *   The structured array describing the data being rendered. Including the
Chris@0:    *   bubbleable metadata associated with the markup that replaced the
Chris@0:    *   placeholders.
Chris@0:    *
Chris@0:    * @returns bool
Chris@0:    *   Whether placeholders were replaced.
Chris@0:    *
Chris@0:    * @see \Drupal\Core\Render\Renderer::renderPlaceholder()
Chris@0:    */
Chris@0:   protected function replacePlaceholders(array &$elements) {
Chris@0:     if (!isset($elements['#attached']['placeholders']) || empty($elements['#attached']['placeholders'])) {
Chris@0:       return FALSE;
Chris@0:     }
Chris@0: 
Chris@0:     // The 'status messages' placeholder needs to be special cased, because it
Chris@0:     // depends on global state that can be modified when other placeholders are
Chris@0:     // being rendered: any code can add messages to render.
Chris@0:     // This violates the principle that each lazy builder must be able to render
Chris@0:     // itself in isolation, and therefore in any order. However, we cannot
Chris@17:     // change the way \Drupal\Core\Messenger\Messenger works in the Drupal 8
Chris@17:     // cycle. So we have to accommodate its special needs.
Chris@0:     // Allowing placeholders to be rendered in a particular order (in this case:
Chris@0:     // last) would violate this isolation principle. Thus a monopoly is granted
Chris@0:     // to this one special case, with this hard-coded solution.
Chris@0:     // @see \Drupal\Core\Render\Element\StatusMessages
Chris@0:     // @see https://www.drupal.org/node/2712935#comment-11368923
Chris@0: 
Chris@0:     // First render all placeholders except 'status messages' placeholders.
Chris@0:     $message_placeholders = [];
Chris@0:     foreach ($elements['#attached']['placeholders'] as $placeholder => $placeholder_element) {
Chris@0:       if (isset($placeholder_element['#lazy_builder']) && $placeholder_element['#lazy_builder'][0] === 'Drupal\Core\Render\Element\StatusMessages::renderMessages') {
Chris@0:         $message_placeholders[] = $placeholder;
Chris@0:       }
Chris@0:       else {
Chris@0:         $elements = $this->renderPlaceholder($placeholder, $elements);
Chris@0:       }
Chris@0:     }
Chris@0: 
Chris@0:     // Then render 'status messages' placeholders.
Chris@0:     foreach ($message_placeholders as $message_placeholder) {
Chris@0:       $elements = $this->renderPlaceholder($message_placeholder, $elements);
Chris@0:     }
Chris@0: 
Chris@0:     return TRUE;
Chris@0:   }
Chris@0: 
Chris@0:   /**
Chris@0:    * {@inheritdoc}
Chris@0:    */
Chris@0:   public function mergeBubbleableMetadata(array $a, array $b) {
Chris@0:     $meta_a = BubbleableMetadata::createFromRenderArray($a);
Chris@0:     $meta_b = BubbleableMetadata::createFromRenderArray($b);
Chris@0:     $meta_a->merge($meta_b)->applyTo($a);
Chris@0:     return $a;
Chris@0:   }
Chris@0: 
Chris@0:   /**
Chris@0:    * {@inheritdoc}
Chris@0:    */
Chris@0:   public function addCacheableDependency(array &$elements, $dependency) {
Chris@0:     $meta_a = CacheableMetadata::createFromRenderArray($elements);
Chris@0:     $meta_b = CacheableMetadata::createFromObject($dependency);
Chris@0:     $meta_a->merge($meta_b)->applyTo($elements);
Chris@0:   }
Chris@0: 
Chris@0:   /**
Chris@0:    * Applies a very permissive XSS/HTML filter for admin-only use.
Chris@0:    *
Chris@0:    * Note: This method only filters if $string is not marked safe already. This
Chris@0:    * ensures that HTML intended for display is not filtered.
Chris@0:    *
Chris@0:    * @param string|\Drupal\Core\Render\Markup $string
Chris@0:    *   A string.
Chris@0:    *
Chris@0:    * @return \Drupal\Core\Render\Markup
Chris@0:    *   The escaped string wrapped in a Markup object. If the string is an
Chris@0:    *   instance of \Drupal\Component\Render\MarkupInterface, it won't be escaped
Chris@0:    *   again.
Chris@0:    */
Chris@0:   protected function xssFilterAdminIfUnsafe($string) {
Chris@0:     if (!($string instanceof MarkupInterface)) {
Chris@0:       $string = Xss::filterAdmin($string);
Chris@0:     }
Chris@0:     return Markup::create($string);
Chris@0:   }
Chris@0: 
Chris@0:   /**
Chris@0:    * Escapes #plain_text or filters #markup as required.
Chris@0:    *
Chris@0:    * Drupal uses Twig's auto-escape feature to improve security. This feature
Chris@0:    * automatically escapes any HTML that is not known to be safe. Due to this
Chris@0:    * the render system needs to ensure that all markup it generates is marked
Chris@0:    * safe so that Twig does not do any additional escaping.
Chris@0:    *
Chris@0:    * By default all #markup is filtered to protect against XSS using the admin
Chris@0:    * tag list. Render arrays can alter the list of tags allowed by the filter
Chris@0:    * using the #allowed_tags property. This value should be an array of tags
Chris@0:    * that Xss::filter() would accept. Render arrays can escape text instead
Chris@0:    * of XSS filtering by setting the #plain_text property instead of #markup. If
Chris@0:    * #plain_text is used #allowed_tags is ignored.
Chris@0:    *
Chris@0:    * @param array $elements
Chris@0:    *   A render array with #markup set.
Chris@0:    *
Chris@0:    * @return \Drupal\Component\Render\MarkupInterface|string
Chris@0:    *   The escaped markup wrapped in a Markup object. If $elements['#markup']
Chris@0:    *   is an instance of \Drupal\Component\Render\MarkupInterface, it won't be
Chris@0:    *   escaped or filtered again.
Chris@0:    *
Chris@0:    * @see \Drupal\Component\Utility\Html::escape()
Chris@0:    * @see \Drupal\Component\Utility\Xss::filter()
Chris@0:    * @see \Drupal\Component\Utility\Xss::filterAdmin()
Chris@0:    */
Chris@0:   protected function ensureMarkupIsSafe(array $elements) {
Chris@16:     if (isset($elements['#plain_text'])) {
Chris@0:       $elements['#markup'] = Markup::create(Html::escape($elements['#plain_text']));
Chris@0:     }
Chris@0:     elseif (!($elements['#markup'] instanceof MarkupInterface)) {
Chris@0:       // The default behaviour is to XSS filter using the admin tag list.
Chris@0:       $tags = isset($elements['#allowed_tags']) ? $elements['#allowed_tags'] : Xss::getAdminTagList();
Chris@0:       $elements['#markup'] = Markup::create(Xss::filter($elements['#markup'], $tags));
Chris@0:     }
Chris@0: 
Chris@0:     return $elements;
Chris@0:   }
Chris@0: 
Chris@0: }