Creates a placeholder.

This generates its own placeholder markup for one major reason: to not have FilterProcessResult depend on the Renderer service, because this is a value object. As a side-effect and added benefit, this makes it easier to distinguish placeholders for filtered text versus generic render system placeholders.

Parameters

string $callback: The #lazy_builder callback that will replace the placeholder with its eventual markup.

array $args: The arguments for the #lazy_builder callback.

Return value

string The placeholder markup.

File

core/modules/filter/src/FilterProcessResult.php, line 134

Class

FilterProcessResult

Used to return values from a text filter plugin's processing method.

Namespace

Drupal\filter

Code

public function createPlaceholder($callback, array $args) {
  // Generate placeholder markup.
  // @see \Drupal\Core\Render\PlaceholderGenerator::createPlaceholder()
  $arguments = UrlHelper::buildQuery($args);
  $token = Crypt::hashBase64(serialize([
    $callback,
    $args,
  ]));
  $placeholder_markup = '<drupal-filter-placeholder callback="' . Html::escape($callback) . '"';
  if ($arguments !== '') {
    $placeholder_markup .= ' arguments="' . Html::escape($arguments) . '"';
  }
  $placeholder_markup .= ' token="' . Html::escape($token) . '"></drupal-filter-placeholder>';
  // Add the placeholder attachment.
  $this->addAttachments([
    'placeholders' => [
      $placeholder_markup => [
        '#lazy_builder' => [
          $callback,
          $args,
        ],
      ],
    ],
  ]);
  // Return the placeholder markup, so that the filter wanting to use a
  // placeholder can actually insert the placeholder markup where it needs the
  // placeholder to be replaced.
  return $placeholder_markup;
}

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