protected Renderer::replacePlaceholders(array &$elements)
Replaces placeholders.
Placeholders may have:
- #lazy_builder callback, to build a render array to be rendered into markup that can replace the placeholder
- #cache: to cache the result of the placeholder
Also merges the bubbleable metadata resulting from the rendering of the contents of the placeholders. Hence $elements will be contain the entirety of bubbleable metadata.
@returns bool Whether placeholders were replaced.
Parameters
array &$elements: The structured array describing the data being rendered. Including the bubbleable metadata associated with the markup that replaced the placeholders.
See also
\Drupal\Core\Render\Renderer::renderPlaceholder()
File
- core/lib/Drupal/Core/Render/Renderer.php, line 634
Class
- Renderer
- Turns a render array into a HTML string.
Namespace
Drupal\Core\Render
Code
protected function replacePlaceholders(array &$elements) { if (!isset($elements['#attached']['placeholders']) || empty($elements['#attached']['placeholders'])) { return FALSE; } // The 'status messages' placeholder needs to be special cased, because it // depends on global state that can be modified when other placeholders are // being rendered: any code can add messages to render. // This violates the principle that each lazy builder must be able to render // itself in isolation, and therefore in any order. However, we cannot // change the way drupal_set_message() works in the Drupal 8 cycle. So we // have to accommodate its special needs. // Allowing placeholders to be rendered in a particular order (in this case: // last) would violate this isolation principle. Thus a monopoly is granted // to this one special case, with this hard-coded solution. // @see \Drupal\Core\Render\Element\StatusMessages // @see https://www.drupal.org/node/2712935#comment-11368923 // First render all placeholders except 'status messages' placeholders. $message_placeholders = []; foreach ($elements['#attached']['placeholders'] as $placeholder => $placeholder_element) { if (isset($placeholder_element['#lazy_builder']) && $placeholder_element['#lazy_builder'][0] === 'Drupal\Core\Render\Element\StatusMessages::renderMessages') { $message_placeholders[] = $placeholder; } else { $elements = $this->renderPlaceholder($placeholder, $elements); } } // Then render 'status messages' placeholders. foreach ($message_placeholders as $message_placeholder) { $elements = $this->renderPlaceholder($message_placeholder, $elements); } return TRUE; }
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