edlp_d8/sites/all/modules/contrib/admin/better_messages/better_messages.module

<?php

/**
 *  Implements hook_theme().
 */
function better_messages_theme() {
  return [
    'better_messages_wrapper' => [
      'render element' => 'element',
      'variables' => [
        'children' => '',
        'message_list' => [],
      ],
    ],
  ];
}

/**
 * Implements hook_element_info_alter().
 */
function better_messages_element_info_alter(array &$info) {
  // Replace the default pre_render for status_messages with our custom one.
  $info['status_messages']['#pre_render'][0] = 'better_messages_status_messages_pre_render';
}

/**
 * Pre render callback for 'status_messages' render element.
 */
function better_messages_status_messages_pre_render(array $element) {
  // The code below is heavily copied from StatusMessages::renderMessages().
  $element = [
    '#lazy_builder' => ['better_messages_status_messages_lazy_builder', [$element['#display']]],
    '#create_placeholder' => TRUE,
  ];

  // Directly create a placeholder as we need this to be placeholdered
  // regardless if this is a POST or GET request.
  // @todo remove this when https://www.drupal.org/node/2367555 lands.
  return \Drupal::service('render_placeholder_generator')->createPlaceholder($element);
}

/**
 * Lazy builder for 'status_messages'.
 *
 * Improved version of StatusMessages::renderMessages() that additionally wraps
 * the output into an overlay markup whenever necessary.
 *
 * @param string|null $type
 *   Limit the messages returned by type. Defaults to NULL, meaning all types.
 *   Passed on to drupal_get_messages(). These values are supported:
 *   - NULL
 *   - 'status'
 *   - 'warning'
 *   - 'error'
 *
 * @return array
 *   A renderable array containing the messages.
 */
function better_messages_status_messages_lazy_builder($type) {
  $render = \Drupal\Core\Render\Element\StatusMessages::renderMessages($type);
  if (!empty($render)) {
    $render['#theme_wrappers'][] = 'better_messages_wrapper';
    $render['#attached']['library'][] = 'better_messages/better_messages';
    $render['#attached']['drupalSettings']['better_messages'] = \Drupal::config('better_messages.settings')->get();
  }

  return $render;
}

/**
 * Preprocess for 'better_messages_wrapper' theme hook.
 */
function template_preprocess_better_messages_wrapper(&$variables) {
  $settings = \Drupal::config('better_messages.settings');
  $cache = \Drupal\Core\Cache\CacheableMetadata::createFromRenderArray($variables);
  $cache->addCacheTags($settings->getCacheTags());
  $cache->addCacheContexts($settings->getCacheContexts());
  $cache->mergeCacheMaxAge($settings->getCacheMaxAge());

  // Inject the messages from $variables into our "better_messages" context
  // since now we have crossed beyond the point where "current" messages are
  // retrievable via drupal_get_messages().
  \Drupal::service('better_messages.context')->setMessages($variables['message_list']);

  /** @var \Drupal\Core\Condition\ConditionManager $condition_manager */
  $condition_manager = \Drupal::service('plugin.manager.condition');
  /** @var \Drupal\Core\Plugin\Context\ContextRepositoryInterface $context_repository */
  $context_repository = \Drupal::service('context.repository');
  /** @var \Drupal\Core\Plugin\Context\ContextHandlerInterface $context_handler */
  $context_handler = \Drupal::service('context.handler');

  $pass = TRUE;
  foreach ($settings->get('visibility') as $condition_id => $condition) {
    $condition = $condition_manager->createInstance($condition_id, $condition);
    if ($condition instanceof \Drupal\Core\Plugin\ContextAwarePluginInterface) {
      try {
        $contexts = $context_repository->getRuntimeContexts(array_values($condition->getContextMapping()));
        $context_handler->applyContextMapping($condition, $contexts);
      }
      catch (\Drupal\Component\Plugin\Exception\ContextException $e) {
        // We couldn't initialize the condition, so it just cannot participate.
        continue;
      }
    }

    try {
      $pass = $condition->execute();
    }
    catch (\Drupal\Component\Plugin\Exception\ContextException $e) {
      // Condition couldn't evaluate itself. Let's skip it.
      continue;
    }

    if ($condition instanceof \Drupal\Core\Cache\CacheableDependencyInterface) {
      $cache->addCacheTags($condition->getCacheTags());
      $cache->addCacheContexts($condition->getCacheContexts());
      $cache->mergeCacheMaxAge($condition->getCacheMaxAge());
    }

    if (!$pass) {
      break;
    }
  }

  $cache->applyTo($variables);

  if ($pass && !empty($variables['message_list'])) {
    $variables['attributes']['class'][] = 'better-messages-overlay';

    if (\Drupal::config('better_messages.settings')->get('fixed')) {
      $variables['attributes']['class'][] = 'better-messages-position-fixed';
    }

    if (isset($variables['message_list']['error'])) {
      $variables['attributes']['class'][] = 'better-messages-has-errors';
    }
  }
}