Same name and namespace in other branches

1. 9 core/lib/Drupal/Core/Render/Renderer.php \Drupal\Core\Render\Renderer::replacePlaceholders()
2. 8.9.x core/lib/Drupal/Core/Render/Renderer.php \Drupal\Core\Render\Renderer::replacePlaceholders()
3. 11.x core/lib/Drupal/Core/Render/Renderer.php \Drupal\Core\Render\Renderer::replacePlaceholders()

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.

Parameters

array &$elements: The structured array describing the data being rendered. Including the bubbleable metadata associated with the markup that replaced the placeholders.

Return value

bool Whether placeholders were replaced.

See also

\Drupal\Core\Render\Renderer::renderPlaceholder()

1 call to Renderer::replacePlaceholders()

Renderer::doRender in core/lib/Drupal/Core/Render/Renderer.php

See the docs for ::render().

File

core/lib/Drupal/Core/Render/Renderer.php, line 695

Class

Renderer

Turns a render array into an 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\Core\Messenger\Messenger 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 = [];
  $fibers = [];
  foreach ($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 {
      // Get the render array for the given placeholder
      $fibers[$placeholder] = new \Fiber(function () use ($placeholder_element) {
        return [
          $this->doRenderPlaceholder($placeholder_element),
          $placeholder_element,
        ];
      });
    }
  }
  $iterations = 0;
  while (count($fibers) > 0) {
    foreach ($fibers as $placeholder => $fiber) {
      if (!$fiber->isStarted()) {
        $fiber->start();
      }
      elseif ($fiber->isSuspended()) {
        $fiber->resume();
      }
      // If the Fiber hasn't terminated by this point, move onto the next
      // placeholder, we'll resume this fiber again when we get back here.
      if (!$fiber->isTerminated()) {
        // If we've gone through the placeholders once already, and they're
        // still not finished, then start to allow code higher up the stack to
        // get on with something else.
        if ($iterations) {
          $fiber = \Fiber::getCurrent();
          if ($fiber !== NULL) {
            $fiber->suspend();
          }
        }
        continue;
      }
      [
        $markup,
        $placeholder_element,
      ] = $fiber->getReturn();
      $elements = $this->doReplacePlaceholder($placeholder, $markup, $elements, $placeholder_element);
      unset($fibers[$placeholder]);
    }
    $iterations++;
  }
  // Then render 'status messages' placeholders.
  foreach ($message_placeholders as $message_placeholder) {
    $elements = $this->renderPlaceholder($message_placeholder, $elements);
  }
  return TRUE;
}

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