public function PlaceholderGenerator::createPlaceholder

File

core/lib/Drupal/Core/Render/PlaceholderGenerator.php, line 87

Class

PlaceholderGenerator

Turns a render array into a placeholder.

Namespace

Code

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,
  ]);
  if (isset($element['#lazy_builder_preview'])) {
    $placeholder_render_array['#preview'] = $element['#lazy_builder_preview'];
  }

  // Be sure cache contexts and tags are sorted before serializing them and
  // making hash. Issue #3225328 removes sort from contexts and tags arrays
  // for performances reasons.
  if (isset($placeholder_render_array['#cache']['contexts'])) {
    sort($placeholder_render_array['#cache']['contexts']);
  }
  if (isset($placeholder_render_array['#cache']['tags'])) {
    sort($placeholder_render_array['#cache']['tags']);
  }

  // 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) . '"';
  if ($arguments !== '') {
    $placeholder_markup .= ' arguments="' . Html::escape($arguments) . '"';
  }
  $placeholder_markup .= ' token="' . Html::escape($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;
}