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- <?php
- namespace Drupal\Core\Render;
- use Drupal\Component\Utility\Crypt;
- use Drupal\Component\Utility\Html;
- use Drupal\Component\Utility\UrlHelper;
- use Drupal\Core\Cache\Cache;
- /**
- * Turns a render array into a placeholder.
- */
- class PlaceholderGenerator implements PlaceholderGeneratorInterface {
- /**
- * The renderer configuration array.
- *
- * @var array
- */
- protected $rendererConfig;
- /**
- * Constructs a new Placeholder service.
- *
- * @param array $renderer_config
- * The renderer configuration array.
- */
- public function __construct(array $renderer_config) {
- $this->rendererConfig = $renderer_config;
- }
- /**
- * {@inheritdoc}
- */
- public function canCreatePlaceholder(array $element) {
- // If generated by a #lazy_builder callback, placeholdering is possible.
- return isset($element['#lazy_builder']) &&
- // If #create_placeholder === FALSE, placeholdering is disallowed.
- (!isset($element['#create_placeholder']) || $element['#create_placeholder'] !== FALSE);
- }
- /**
- * {@inheritdoc}
- */
- public function shouldAutomaticallyPlaceholder(array $element) {
- // Auto-placeholder if the max-age, cache context or cache tag is specified
- // in the auto-placeholder conditions in the 'renderer.config' container
- // parameter.
- $conditions = $this->rendererConfig['auto_placeholder_conditions'];
- if (isset($element['#cache']['max-age']) && $element['#cache']['max-age'] !== Cache::PERMANENT && $element['#cache']['max-age'] <= $conditions['max-age']) {
- return TRUE;
- }
- if (isset($element['#cache']['contexts']) && array_intersect($element['#cache']['contexts'], $conditions['contexts'])) {
- return TRUE;
- }
- if (isset($element['#cache']['tags']) && array_intersect($element['#cache']['tags'], $conditions['tags'])) {
- return TRUE;
- }
- return FALSE;
- }
- /**
- * {@inheritdoc}
- */
- public function createPlaceholder(array $element) {
- $placeholder_render_array = array_intersect_key($element, [
- // Placeholders are replaced with markup by executing the associated
- // #lazy_builder callback, which generates a render array, and which the
- // Renderer will render and replace the placeholder with.
- '#lazy_builder' => TRUE,
- // The cacheability metadata for the placeholder. The rendered result of
- // the placeholder may itself be cached, if [#cache][keys] are specified.
- '#cache' => TRUE,
- ]);
- // Generate placeholder markup. Note that the only requirement is that this
- // is unique markup that isn't easily guessable. The #lazy_builder callback
- // and its arguments are put in the placeholder markup solely to simplify<<<
- // debugging.
- $callback = $placeholder_render_array['#lazy_builder'][0];
- $arguments = UrlHelper::buildQuery($placeholder_render_array['#lazy_builder'][1]);
- $token = Crypt::hashBase64(serialize($placeholder_render_array));
- $placeholder_markup = '<drupal-render-placeholder callback="' . Html::escape($callback) . '" arguments="' . Html::escape($arguments) . '" token="' . Html::escape($token) . '"></drupal-render-placeholder>';
- // Build the placeholder element to return.
- $placeholder_element = [];
- $placeholder_element['#markup'] = Markup::create($placeholder_markup);
- $placeholder_element['#attached']['placeholders'][$placeholder_markup] = $placeholder_render_array;
- return $placeholder_element;
- }
- }
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