function PlaceholderGenerator::createPlaceholder

Overrides PlaceholderGeneratorInterface::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.
    $placeholder_markup = static::createPlaceholderTag('drupal-render-placeholder', [
        'callback' => $placeholder_render_array['#lazy_builder'][0],
        'arguments' => UrlHelper::buildQuery($placeholder_render_array['#lazy_builder'][1]),
        'token' => Crypt::hashBase64(serialize($placeholder_render_array)),
    ]);
    // 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;
}