DefaultPluginManager.php in Plug 7

Contains \Drupal\Core\Plugin\DefaultPluginManager.

Namespace

Drupal\Core\Plugin

File

lib/Drupal/Core/Plugin/DefaultPluginManager.php

<?php

/**
 * @file
 * Contains \Drupal\Core\Plugin\DefaultPluginManager.
 */
namespace Drupal\Core\Plugin;

use Drupal\Component\FileCache\FileCacheFactory;
use Drupal\Component\Plugin\Discovery\CachedDiscoveryInterface;
use Drupal\Component\Plugin\Discovery\DiscoveryCachedTrait;
use Drupal\Core\Plugin\Discovery\ContainerDerivativeDiscoveryDecorator;
use Drupal\Component\Plugin\PluginManagerBase;
use Drupal\Component\Plugin\PluginManagerInterface;
use Drupal\Component\Utility\NestedArray;
use Drupal\Core\Plugin\Discovery\AnnotatedClassDiscovery;
use Drupal\Core\Plugin\Factory\ContainerFactory;

/**
 * Base class for plugin managers.
 *
 * @ingroup plugin_api
 */
class DefaultPluginManager extends PluginManagerBase implements PluginManagerInterface, CachedDiscoveryInterface {
  use DiscoveryCachedTrait;

  /**
   * Cache backend instance.
   *
   * @var \DrupalCacheInterface
   */
  protected $cacheBackend;

  /**
   * The cache key.
   *
   * @var string
   */
  protected $cacheKey;

  /**
   * Name of the alter hook if one should be invoked.
   *
   * @var string
   */
  protected $alterHook;

  /**
   * The subdirectory within a namespace to look for plugins, or FALSE if the
   * plugins are in the top level of the namespace.
   *
   * @var string|bool
   */
  protected $subdir;

  /**
   * A set of defaults to be referenced by $this->processDefinition() if
   * additional processing of plugins is necessary or helpful for development
   * purposes.
   *
   * @var array
   */
  protected $defaults = array();

  /**
   * Flag whether persistent caches should be used.
   *
   * @var bool
   */
  protected $useCaches = TRUE;

  /**
   * The name of the annotation that contains the plugin definition.
   *
   * @var string
   */
  protected $pluginDefinitionAnnotationName;

  /**
   * The interface each plugin should implement.
   *
   * @var string|null
   */
  protected $pluginInterface;

  /**
   * An object that implements \Traversable which contains the root paths
   * keyed by the corresponding namespace to look for plugin implementations.
   *
   * @var \Traversable
   */
  protected $namespaces;

  /**
   * Creates the discovery object.
   *
   * @param string|bool $subdir
   *   The plugin's subdirectory, for example Plugin/views/filter.
   * @param \Traversable $namespaces
   *   An object that implements \Traversable which contains the root paths
   *   keyed by the corresponding namespace to look for plugin implementations.
   * @param string|null $plugin_interface
   *   (optional) The interface each plugin should implement.
   * @param string $plugin_definition_annotation_name
   *   (optional) The name of the annotation that contains the plugin definition.
   *   Defaults to 'Drupal\Component\Annotation\Plugin'.
   */
  public function __construct($subdir, \Traversable $namespaces, $plugin_interface = NULL, $plugin_definition_annotation_name = 'Drupal\\Component\\Annotation\\Plugin') {
    $this->subdir = $subdir;
    $this->namespaces = $namespaces;
    $this->pluginDefinitionAnnotationName = $plugin_definition_annotation_name;
    $this->pluginInterface = $plugin_interface;

    // Add the file cache prefix.
    $configuration['default'] = [
      'class' => '\\Drupal\\Component\\FileCache\\FileCache',
      'cache_backend_class' => NULL,
      'cache_backend_configuration' => [],
    ];

    // @todo Use extension_loaded('apcu') for non-testbot
    //  https://www.drupal.org/node/2447753.
    if (function_exists('apc_fetch')) {
      $configuration['default']['cache_backend_class'] = '\\Drupal\\Component\\FileCache\\ApcuFileCacheBackend';
    }
    FileCacheFactory::setConfiguration($configuration);
    $identifier = 'file_cache';
    FileCacheFactory::setPrefix('drupal.' . $identifier . '.' . hash_hmac('sha256', $identifier, drupal_get_hash_salt()));
  }

  /**
   * Initialize the cache backend.
   *
   * Plugin definitions are cached using the provided cache backend. The
   * interface language is added as a suffix to the cache key.
   *
   * @param \DrupalCacheInterface $cache_backend
   *   Cache backend instance to use.
   * @param string $cache_key
   *   Cache key prefix to use, the language code will be appended
   *   automatically.
   */
  public function setCacheBackend(\DrupalCacheInterface $cache_backend, $cache_key) {
    $this->cacheBackend = $cache_backend;
    $this->cacheKey = $cache_key;
  }

  /**
   * Initializes the alter hook.
   *
   * @param string $alter_hook
   *   Name of the alter hook; for example, to invoke
   *   hook_mymodule_data_alter() pass in "mymodule_data".
   */
  protected function alterInfo($alter_hook) {
    $this->alterHook = $alter_hook;
  }

  /**
   * {@inheritdoc}
   */
  public function getDefinitions() {
    $definitions = $this
      ->getCachedDefinitions();
    if (!isset($definitions)) {
      $definitions = $this
        ->findDefinitions();
      $this
        ->setCachedDefinitions($definitions);
    }
    return $definitions;
  }

  /**
   * {@inheritdoc}
   */
  public function clearCachedDefinitions() {
    if ($this->cacheBackend) {
      $this->cacheBackend
        ->clear($this->cacheKey);
    }
    $this->definitions = NULL;
  }

  /**
   * Returns the cached plugin definitions of the decorated discovery class.
   *
   * @return array|null
   *   On success this will return an array of plugin definitions. On failure
   *   this should return NULL, indicating to other methods that this has not
   *   yet been defined. Success with no values should return as an empty array
   *   and would actually be returned by the getDefinitions() method.
   */
  protected function getCachedDefinitions() {
    if (!isset($this->definitions) && ($cache = $this
      ->cacheGet($this->cacheKey))) {
      $this->definitions = $cache->data;
    }
    return $this->definitions;
  }

  /**
   * Sets a cache of plugin definitions for the decorated discovery class.
   *
   * @param array $definitions
   *   List of definitions to store in cache.
   */
  protected function setCachedDefinitions($definitions) {
    $this
      ->cacheSet($this->cacheKey, $definitions, CACHE_PERMANENT);
    $this->definitions = $definitions;
  }

  /**
   * {@inheritdoc}
   */
  public function useCaches($use_caches = FALSE) {
    $this->useCaches = $use_caches;
    if (!$use_caches) {
      $this->definitions = NULL;
    }
  }

  /**
   * Fetches from the cache backend, respecting the use caches flag.
   *
   * @see \DrupalCacheInterface::get()
   */
  protected function cacheGet($cid) {
    if ($this->useCaches && $this->cacheBackend) {
      return $this->cacheBackend
        ->get($cid);
    }
    return FALSE;
  }

  /**
   * Stores data in the persistent cache, respecting the use caches flag.
   *
   * @see \DrupalCacheInterface::set()
   */
  protected function cacheSet($cid, $data, $expire = CACHE_PERMANENT, array $tags = array()) {
    if ($this->cacheBackend && $this->useCaches) {
      $this->cacheBackend
        ->set($cid, $data, $expire, $tags);
    }
  }

  /**
   * Performs extra processing on plugin definitions.
   *
   * By default we add defaults for the type to the definition. If a type has
   * additional processing logic they can do that by replacing or extending the
   * method.
   */
  public function processDefinition(&$definition, $plugin_id = NULL) {
    if (!empty($this->defaults) && is_array($this->defaults)) {
      $definition = NestedArray::mergeDeep($this->defaults, $definition);
    }
  }

  /**
   * {@inheritdoc}
   */
  protected function getDiscovery() {
    if (!$this->discovery) {
      $discovery = new AnnotatedClassDiscovery($this->subdir, $this->namespaces, $this->pluginDefinitionAnnotationName);
      $this->discovery = new ContainerDerivativeDiscoveryDecorator($discovery);
    }
    return $this->discovery;
  }

  /**
   * {@inheritdoc}
   */
  protected function getFactory() {
    if (!$this->factory) {
      $this->factory = new ContainerFactory($this, $this->pluginInterface);
    }
    return $this->factory;
  }

  /**
   * Finds plugin definitions.
   *
   * @return array
   *   List of definitions to store in cache.
   */
  protected function findDefinitions() {
    $definitions = $this
      ->getDiscovery()
      ->getDefinitions();
    foreach ($definitions as $plugin_id => &$definition) {
      $this
        ->processDefinition($definition, $plugin_id);
    }
    $this
      ->alterDefinitions($definitions);

    // If this plugin was provided by a module that does not exist, remove the
    // plugin definition.
    foreach ($definitions as $plugin_id => $plugin_definition) {

      // If the plugin definition is an object, attempt to convert it to an
      // array, if that is not possible, skip further processing.
      if (is_object($plugin_definition) && !($plugin_definition = (array) $plugin_definition)) {
        continue;
      }
      if (isset($plugin_definition['provider']) && !in_array($plugin_definition['provider'], array(
        'core',
        'component',
      )) && !$this
        ->providerExists($plugin_definition['provider'])) {
        unset($definitions[$plugin_id]);
      }
    }
    return $definitions;
  }

  /**
   * Invokes the hook to alter the definitions if the alter hook is set.
   *
   * @param $definitions
   *   The discovered plugin defintions.
   */
  protected function alterDefinitions(&$definitions) {
    if ($this->alterHook) {
      drupal_alter($this->alterHook, $definitions);
    }
  }

  /**
   * Determines if the provider of a definition exists.
   *
   * @return boolean
   *   TRUE if provider exists, FALSE otherwise.
   */
  protected function providerExists($provider) {
    return module_exists($provider);
  }

}

Classes

Name	Description
DefaultPluginManager	Base class for plugin managers.