class ThemeRegistry

Same name and namespace in other branches
  1. 11.x core/lib/Drupal/Core/Utility/ThemeRegistry.php \Drupal\Core\Utility\ThemeRegistry
  2. 7.x includes/theme.inc \ThemeRegistry
  3. 10 core/lib/Drupal/Core/Utility/ThemeRegistry.php \Drupal\Core\Utility\ThemeRegistry
  4. 8.9.x core/lib/Drupal/Core/Utility/ThemeRegistry.php \Drupal\Core\Utility\ThemeRegistry

Builds the run-time theme registry.

A cache collector to allow the theme registry to be accessed as a complete registry, while internally caching only the parts of the registry that are actually in use on the site. On cache misses the complete theme registry is loaded and used to update the run-time cache.

Hierarchy

Expanded class hierarchy of ThemeRegistry

2 files declare their use of ThemeRegistry
Registry.php in core/lib/Drupal/Core/Theme/Registry.php
RegistryTest.php in core/tests/Drupal/KernelTests/Core/Theme/RegistryTest.php

File

core/lib/Drupal/Core/Utility/ThemeRegistry.php, line 19

Namespace

Drupal\Core\Utility
View source
class ThemeRegistry extends CacheCollector implements DestructableInterface {
  
  /**
   * Whether the partial registry can be persisted to the cache.
   *
   * This is only allowed if all modules and the request method is GET. _theme()
   * should be very rarely called on POST requests and this avoids polluting
   * the runtime cache.
   *
   * @var bool
   */
  protected $persistable;
  
  /**
   * The complete theme registry array.
   */
  protected $completeRegistry;
  
  /**
   * Constructs a ThemeRegistry object.
   *
   * @param string $cid
   *   The cid for the array being cached.
   * @param \Drupal\Core\Cache\CacheBackendInterface $cache
   *   The cache backend.
   * @param \Drupal\Core\Lock\LockBackendInterface $lock
   *   The lock backend.
   * @param array $tags
   *   (optional) The tags to specify for the cache item.
   * @param bool $modules_loaded
   *   Whether all modules have already been loaded.
   */
  public function __construct($cid, CacheBackendInterface $cache, LockBackendInterface $lock, $tags = [], $modules_loaded = FALSE) {
    $this->cid = $cid;
    $this->cache = $cache;
    $this->lock = $lock;
    $this->tags = $tags;
    $this->persistable = $modules_loaded && \Drupal::hasRequest() && \Drupal::request()->isMethod('GET');
    // @todo: Implement lazyload.
    $this->cacheLoaded = TRUE;
    if ($this->persistable && $cached = $this->cache
      ->get($this->cid)) {
      $this->storage = $cached->data;
    }
    else {
      // If there is no runtime cache stored, fetch the full theme registry,
      // but then initialize each value to NULL. This allows offsetExists()
      // to function correctly on non-registered theme hooks without triggering
      // a call to resolveCacheMiss().
      $this->storage = $this->initializeRegistry();
      foreach (array_keys($this->storage) as $key) {
        $this->persist($key);
      }
      // RegistryTest::testRaceCondition() ensures that the cache entry is
      // written on the initial construction of the theme registry.
      $this->updateCache();
    }
  }
  
  /**
   * Initializes the full theme registry.
   *
   * @return array
   *   An array with the keys of the full theme registry, but the values
   *   initialized to NULL.
   */
  public function initializeRegistry() {
    // @todo DIC this.
    $this->completeRegistry = \Drupal::service('theme.registry')->get();
    return array_fill_keys(array_keys($this->completeRegistry), NULL);
  }
  
  /**
   * {@inheritdoc}
   */
  public function has($key) {
    // Since the theme registry allows for theme hooks to be requested that
    // are not registered, just check the existence of the key in the registry.
    // Use array_key_exists() here since a NULL value indicates that the theme
    // hook exists but has not yet been requested.
    return isset($this->storage[$key]) || array_key_exists($key, $this->storage);
  }
  
  /**
   * {@inheritdoc}
   */
  public function get($key) {
    // If the offset is set but empty, it is a registered theme hook that has
    // not yet been requested. Offsets that do not exist at all were not
    // registered in hook_theme().
    if (isset($this->storage[$key])) {
      return $this->storage[$key];
    }
    elseif (array_key_exists($key, $this->storage)) {
      return $this->resolveCacheMiss($key);
    }
  }
  
  /**
   * {@inheritdoc}
   */
  public function resolveCacheMiss($key) {
    if (!isset($this->completeRegistry)) {
      $this->completeRegistry = \Drupal::service('theme.registry')->get();
    }
    $this->storage[$key] = $this->completeRegistry[$key];
    if ($this->persistable) {
      $this->persist($key);
    }
    return $this->storage[$key];
  }
  
  /**
   * {@inheritdoc}
   */
  protected function updateCache($lock = TRUE) {
    if (!$this->persistable) {
      return;
    }
    // @todo: Is the custom implementation necessary?
    $data = [];
    foreach ($this->keysToPersist as $offset => $persist) {
      if ($persist) {
        $data[$offset] = $this->storage[$offset];
      }
    }
    if (empty($data)) {
      return;
    }
    $lock_name = $this->cid . ':' . __CLASS__;
    if (!$lock || $this->lock
      ->acquire($lock_name)) {
      if ($cached = $this->cache
        ->get($this->cid)) {
        // Use array merge instead of union so that filled in values in $data
        // overwrite empty values in the current cache.
        $data = array_merge($cached->data, $data);
      }
      else {
        $registry = $this->initializeRegistry();
        $data = array_merge($registry, $data);
      }
      $this->cache
        ->set($this->cid, $data, Cache::PERMANENT, $this->tags);
      if ($lock) {
        $this->lock
          ->release($lock_name);
      }
    }
  }

}

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