Issue #2033383 by tim.plunkett: Provide a default plugin bag.

core/lib/Drupal/Component/Plugin/ConfigurablePluginInterface.php

+<?php
+
+/**
+ * @file
+ * Contains \Drupal\Component\Plugin\ConfigurablePluginInterface.
+ */
+
+namespace Drupal\Component\Plugin;
+
+/**
+ * Provides an interface for a configurable plugin.
+ */
+interface ConfigurablePluginInterface {
+
+  /**
+   * Returns this plugin's configuration.
+   *
+   * @return array
+   *   An array of this plugin's configuration.
+   */
+  public function getConfiguration();
+
+  /**
+   * Sets the configuration for this plugin instance.
+   *
+   * @param array $configuration
+   *   An associative array containing the plugin's configuration.
+   */
+  public function setConfiguration(array $configuration);
+
+}

core/lib/Drupal/Component/Plugin/DefaultPluginBag.php

+<?php
+
+/**
+ * @file
+ * Contains \Drupal\Component\Plugin\DefaultPluginBag.
+ */
+
+namespace Drupal\Component\Plugin;
+
+use Drupal\Component\Plugin\Exception\PluginException;
+use Drupal\Component\Utility\MapArray;
+use Drupal\Component\Utility\String;
+
+/**
+ * Provides a default plugin bag for a plugin type.
+ *
+ * A plugin bag is used to contain plugins that will be lazily instantiated. The
+ * configurations of each potential plugin are passed in, and the configuration
+ * key containing the plugin ID is specified by self::$pluginKey.
+ */
+class DefaultPluginBag extends PluginBag {
+
+  /**
+   * The manager used to instantiate the plugins.
+   *
+   * @var \Drupal\Component\Plugin\PluginManagerInterface
+   */
+  protected $manager;
+
+  /**
+   * The initial configuration for each plugin in the bag.
+   *
+   * @var array
+   *   An associative array containing the initial configuration for each plugin
+   *   in the bag, keyed by plugin instance ID.
+   */
+  protected $configurations = array();
+
+  /**
+   * The key within the plugin configuration that contains the plugin ID.
+   *
+   * @var string
+   */
+  protected $pluginKey = 'id';
+
+  /**
+   * Constructs a new DefaultPluginBag object.
+   *
+   * @param \Drupal\Component\Plugin\PluginManagerInterface $manager
+   *   The manager to be used for instantiating plugins.
+   * @param array $configurations
+   *   (optional) An associative array containing the initial configuration for
+   *   each plugin in the bag, keyed by plugin instance ID.
+   */
+  public function __construct(PluginManagerInterface $manager, array $configurations = array()) {
+    $this->manager = $manager;
+    $this->configurations = $configurations;
+
+    if (!empty($configurations)) {
+      $this->instanceIDs = MapArray::copyValuesToKeys(array_keys($configurations));
+    }
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function initializePlugin($instance_id) {
+    $configuration = $this->configurations[$instance_id];
+    if (!isset($configuration[$this->pluginKey])) {
+      throw new PluginException(String::format("Unknown plugin ID '@instance'.", array('@instance' => $instance_id)));
+    }
+    $this->pluginInstances[$instance_id] = $this->manager->createInstance($configuration[$this->pluginKey], $configuration);
+    $this->addInstanceID($instance_id);
+  }
+
+  /**
+   * Sorts all plugin instances in this bag.
+   *
+   * @return self
+   *   Returns the plugin bag.
+   */
+  public function sort() {
+    uasort($this->instanceIDs, array($this, 'sortHelper'));
+    return $this;
+  }
+
+  /**
+   * Provides uasort() callback to sort plugins.
+   */
+  public function sortHelper($aID, $bID) {
+    $a = $this->get($aID);
+    $b = $this->get($bID);
+    return strnatcasecmp($a->getPluginId(), $b->getPluginId());
+  }
+
+  /**
+   * Returns the current configuration of all plugins in this bag.
+   *
+   * @return array
+   *   An associative array keyed by instance ID, whose values are up-to-date
+   *   plugin configurations.
+   */
+  public function getConfiguration() {
+    $instances = array();
+    $this->rewind();
+    foreach ($this as $instance_id => $instance) {
+      if ($instance instanceof ConfigurablePluginInterface) {
+        $instances[$instance_id] = $instance->getConfiguration();
+      }
+      else {
+        $instances[$instance_id] = $this->configurations[$instance_id];
+      }
+    }
+    return $instances;
+  }
+
+  /**
+   * Updates the configuration for a plugin instance.
+   *
+   * If there is no plugin instance yet, a new will be instantiated. Otherwise,
+   * the existing instance is updated with the new configuration.
+   *
+   * @param string $instance_id
+   *   The ID of a plugin to set the configuration for.
+   * @param array $configuration
+   *   The plugin configuration to set.
+   */
+  public function setConfiguration($instance_id, array $configuration) {
+    $this->configurations[$instance_id] = $configuration;
+    $instance = $this->get($instance_id);
+    if ($instance instanceof ConfigurablePluginInterface) {
+      $instance->setConfiguration($configuration);
+    }
+  }
+
+}

core/lib/Drupal/Component/Plugin/DefaultSinglePluginBag.php

+<?php
+
+/**
+ * @file
+ * Contains \Drupal\Component\Plugin\DefaultSinglePluginBag.
+ */
+
+namespace Drupal\Component\Plugin;
+
+use Drupal\Component\Utility\MapArray;
+
+/**
+ * Provides a default plugin bag for a plugin type.
+ *
+ * A plugin bag usually stores multiple plugins, and is used to lazily
+ * instantiate them. When only one plugin is needed, it is still best practice
+ * to encapsulate all of the instantiation logic in a plugin bag. This class can
+ * be used directly, or subclassed to add further exception handling in
+ * self::initializePlugin().
+ */
+class DefaultSinglePluginBag extends PluginBag {
+
+  /**
+   * The manager used to instantiate the plugins.
+   *
+   * @var \Drupal\Component\Plugin\PluginManagerInterface
+   */
+  protected $manager;
+
+  /**
+   * An array of configuration to instantiate the plugin with.
+   *
+   * @var array
+   */
+  protected $configuration;
+
+  /**
+   * Constructs a new DefaultSinglePluginBag object.
+   *
+   * @param \Drupal\Component\Plugin\PluginManagerInterface $manager
+   *   The manager to be used for instantiating plugins.
+   * @param array $instance_ids
+   *   The IDs of the plugin instances with which we are dealing.
+   * @param array $configuration
+   *   An array of configuration.
+   */
+  public function __construct(PluginManagerInterface $manager, array $instance_ids, array $configuration) {
+    $this->manager = $manager;
+    $this->instanceIDs = MapArray::copyValuesToKeys($instance_ids);
+    $this->configuration = $configuration;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function initializePlugin($instance_id) {
+    $this->pluginInstances[$instance_id] = $this->manager->createInstance($instance_id, $this->configuration);
+  }
+
+}

core/lib/Drupal/Core/Action/ActionBag.php

@@ -7,46 +7,20 @@
 
 namespace Drupal\Core\Action;
 
-use Drupal\Component\Plugin\PluginBag;
-use Drupal\Component\Plugin\PluginManagerInterface;
+use Drupal\Component\Plugin\DefaultSinglePluginBag;
 
 /**
  * Provides a container for lazily loading Action plugins.
  */
-class ActionBag extends PluginBag {
-
-  /**
-   * The manager used to instantiate the plugins.
-   *
-   * @var \Drupal\Component\Plugin\PluginManagerInterface
-   */
-  protected $manager;
-
-  /**
-   * Constructs a new ActionBag object.
-   *
-   * @param \Drupal\Component\Plugin\PluginManagerInterface $manager
-   *   The manager to be used for instantiating plugins.
-   * @param array $instance_ids
-   *   The ids of the plugin instances with which we are dealing.
-   * @param array $configuration
-   *   An array of configuration.
-   */
-  public function __construct(PluginManagerInterface $manager, array $instance_ids, array $configuration) {
-    $this->manager = $manager;
-    $this->instanceIDs = drupal_map_assoc($instance_ids);
-    $this->configuration = $configuration;
-  }
+class ActionBag extends DefaultSinglePluginBag {
 
   /**
    * {@inheritdoc}
+   *
+   * @return \Drupal\Core\Action\ActionInterface
    */
-  protected function initializePlugin($instance_id) {
-    if (isset($this->pluginInstances[$instance_id])) {
-      return;
-    }
-
-    $this->pluginInstances[$instance_id] = $this->manager->createInstance($instance_id, $this->configuration);
+  public function &get($instance_id) {
+    return parent::get($instance_id);
   }
 
 }

core/lib/Drupal/Core/Action/ConfigurableActionBase.php

@@ -7,13 +7,14 @@
 
 namespace Drupal\Core\Action;
 
-use Drupal\Core\Action\ConfigurableActionInterface;
+use Drupal\Component\Plugin\ConfigurablePluginInterface;
 use Drupal\Core\Action\ActionBase;
+use Drupal\Core\Plugin\PluginFormInterface;
 
 /**
  * Provides a base implementation for a configurable Action plugin.
  */
-abstract class ConfigurableActionBase extends ActionBase implements ConfigurableActionInterface {
+abstract class ConfigurableActionBase extends ActionBase implements ConfigurablePluginInterface, PluginFormInterface {
 
   /**
    * {@inheritdoc}
@@ -43,7 +44,14 @@ public function getConfiguration() {
   /**
    * {@inheritdoc}
    */
-  public function validate(array &$form, array &$form_state) {
+  public function setConfiguration(array $configuration) {
+    $this->configuration = $configuration;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function validateConfigurationForm(array &$form, array &$form_state) {
   }
 
 }

core/lib/Drupal/Core/Plugin/Discovery/AlterDecorator.php

@@ -23,7 +23,7 @@ class AlterDecorator implements DiscoveryInterface {
   /**
    * The Discovery object being decorated.
    *
-   * @var Drupal\Component\Plugin\Discovery\DiscoveryInterface
+   * @var \Drupal\Component\Plugin\Discovery\DiscoveryInterface
    */
   protected $decorated;
 
@@ -32,7 +32,7 @@ class AlterDecorator implements DiscoveryInterface {
    *
    * It uses the DiscoveryInterface object it should decorate.
    *
-   * @param Drupal\Component\Plugin\Discovery\DiscoveryInterface $decorated
+   * @param \Drupal\Component\Plugin\Discovery\DiscoveryInterface $decorated
    *   The object implementing DiscoveryInterface that is being decorated.
    * @param string $hook
    *   The name of the alter hook that will be used by this discovery instance.
@@ -56,7 +56,7 @@ public function getDefinition($plugin_id) {
    */
   public function getDefinitions() {
     $definitions = $this->decorated->getDefinitions();
-    drupal_alter($this->hook, $definitions);
+    \Drupal::moduleHandler()->alter($this->hook, $definitions);
     return $definitions;
   }
 

core/lib/Drupal/Core/Action/ConfigurableActionInterface.php → core/lib/Drupal/Core/Plugin/PluginFormInterface.php

@@ -2,28 +2,15 @@
 
 /**
  * @file
- * Contains \Drupal\Core\Action\ConfigurableActionInterface.
+ * Contains \Drupal\Core\Plugin\PluginFormInterface.
  */
 
-namespace Drupal\Core\Action;
-
-use Drupal\Core\Action\ActionInterface;
+namespace Drupal\Core\Plugin;
 
 /**
- * Provides an interface for an Action plugin.
- *
- * @see \Drupal\Core\Annotation\Operation
- * @see \Drupal\Core\Action\OperationManager
+ * Provides an interface for a plugin that contains a form.
  */
-interface ConfigurableActionInterface extends ActionInterface {
-
-  /**
-   * Returns this plugin's configuration.
-   *
-   * @return array
-   *   An array of this action plugin's configuration.
-   */
-  public function getConfiguration();
+interface PluginFormInterface {
 
   /**
    * Form constructor.
@@ -36,7 +23,7 @@ public function getConfiguration();
    * @return array
    *   The form structure.
    */
-  public function form(array $form, array &$form_state);
+  public function buildConfigurationForm(array $form, array &$form_state);
 
   /**
    * Form validation handler.
@@ -46,16 +33,21 @@ public function form(array $form, array &$form_state);
    * @param array $form_state
    *   An associative array containing the current state of the form.
    */
-  public function validate(array &$form, array &$form_state);
+  public function validateConfigurationForm(array &$form, array &$form_state);
 
   /**
    * Form submission handler.
    *
+   * To properly store submitted form values store them in $this->configuration.
+   * @code
+   *   $this->configuration['some_value'] = $form_state['values']['some_value'];
+   * @endcode
+   *
    * @param array $form
    *   An associative array containing the structure of the form.
    * @param array $form_state
    *   An associative array containing the current state of the form.
    */
-  public function submit(array &$form, array &$form_state);
+  public function submitConfigurationForm(array &$form, array &$form_state);
 
 }

core/modules/action/lib/Drupal/action/ActionFormControllerBase.php

@@ -10,8 +10,8 @@
 use Drupal\Core\Entity\EntityControllerInterface;
 use Drupal\Core\Entity\EntityFormController;
 use Drupal\Core\Extension\ModuleHandlerInterface;
-use Drupal\Core\Action\ConfigurableActionInterface;
 use Drupal\Core\Entity\EntityStorageControllerInterface;
+use Drupal\Core\Plugin\PluginFormInterface;
 use Symfony\Component\DependencyInjection\ContainerInterface;
 
 /**
@@ -97,8 +97,8 @@ public function form(array $form, array &$form_state) {
       '#value' => $this->entity->getType(),
     );
 
-    if ($this->plugin instanceof ConfigurableActionInterface) {
-      $form += $this->plugin->form($form, $form_state);
+    if ($this->plugin instanceof PluginFormInterface) {
+      $form += $this->plugin->buildConfigurationForm($form, $form_state);
     }
 
     return parent::form($form, $form_state);
@@ -133,8 +133,8 @@ protected function actions(array $form, array &$form_state) {
   public function validate(array $form, array &$form_state) {
     parent::validate($form, $form_state);
 
-    if ($this->plugin instanceof ConfigurableActionInterface) {
-      $this->plugin->validate($form, $form_state);
+    if ($this->plugin instanceof PluginFormInterface) {
+      $this->plugin->validateConfigurationForm($form, $form_state);
     }
   }
 
@@ -144,8 +144,8 @@ public function validate(array $form, array &$form_state) {
   public function submit(array $form, array &$form_state) {
     parent::submit($form, $form_state);
 
-    if ($this->plugin instanceof ConfigurableActionInterface) {
-      $this->plugin->submit($form, $form_state);
+    if ($this->plugin instanceof PluginFormInterface) {
+      $this->plugin->submitConfigurationForm($form, $form_state);
     }
     return $this->entity;
   }

core/modules/action/lib/Drupal/action/Form/ActionAdminManageForm.php

@@ -57,7 +57,7 @@ public function getFormID() {
   public function buildForm(array $form, array &$form_state) {
     $actions = array();
     foreach ($this->manager->getDefinitions() as $id => $definition) {
-      if (is_subclass_of($definition['class'], '\Drupal\Core\Action\ConfigurableActionInterface')) {
+      if (is_subclass_of($definition['class'], '\Drupal\Core\Plugin\PluginFormInterface')) {
         $key = Crypt::hashBase64($id);
         $actions[$key] = $definition['label'] . '...';
       }

core/modules/action/lib/Drupal/action/Plugin/Action/EmailAction.php

@@ -116,7 +116,7 @@ protected function getDefaultConfiguration() {
   /**
    * {@inheritdoc}
    */
-  public function form(array $form, array &$form_state) {
+  public function buildConfigurationForm(array $form, array &$form_state) {
     $form['recipient'] = array(
       '#type' => 'textfield',
       '#title' => t('Recipient'),
@@ -145,7 +145,7 @@ public function form(array $form, array &$form_state) {
   /**
    * {@inheritdoc}
    */
-  public function validate(array &$form, array &$form_state) {
+  public function validateConfigurationForm(array &$form, array &$form_state) {
     if (!valid_email_address($form_state['values']['recipient']) && strpos($form_state['values']['recipient'], ':mail') === FALSE) {
       // We want the literal %author placeholder to be emphasized in the error message.
       form_set_error('recipient', t('Enter a valid email address or use a token e-mail address such as %author.', array('%author' => '[node:author:mail]')));
@@ -155,7 +155,7 @@ public function validate(array &$form, array &$form_state) {
   /**
    * {@inheritdoc}
    */
-  public function submit(array &$form, array &$form_state) {
+  public function submitConfigurationForm(array &$form, array &$form_state) {
     $this->configuration['recipient'] = $form_state['values']['recipient'];
     $this->configuration['subject'] = $form_state['values']['subject'];
     $this->configuration['message'] = $form_state['values']['message'];

core/modules/action/lib/Drupal/action/Plugin/Action/GotoAction.php

@@ -96,7 +96,7 @@ protected function getDefaultConfiguration() {
   /**
    * {@inheritdoc}
    */
-  public function form(array $form, array &$form_state) {
+  public function buildConfigurationForm(array $form, array &$form_state) {
     $form['url'] = array(
       '#type' => 'textfield',
       '#title' => t('URL'),
@@ -110,7 +110,7 @@ public function form(array $form, array &$form_state) {
   /**
    * {@inheritdoc}
    */
-  public function submit(array &$form, array &$form_state) {
+  public function submitConfigurationForm(array &$form, array &$form_state) {
     $this->configuration['url'] = $form_state['values']['url'];
   }
 

core/modules/action/lib/Drupal/action/Plugin/Action/MessageAction.php

@@ -70,7 +70,7 @@ protected function getDefaultConfiguration() {
   /**
    * {@inheritdoc}
    */
-  public function form(array $form, array &$form_state) {
+  public function buildConfigurationForm(array $form, array &$form_state) {
     $form['message'] = array(
       '#type' => 'textarea',
       '#title' => t('Message'),
@@ -85,7 +85,7 @@ public function form(array $form, array &$form_state) {
   /**
    * {@inheritdoc}
    */
-  public function submit(array &$form, array &$form_state) {
+  public function submitConfigurationForm(array &$form, array &$form_state) {
     $this->configuration['message'] = $form_state['values']['message'];
     unset($this->configuration['node']);
   }

core/modules/block/lib/Drupal/block/BlockBase.php

@@ -50,50 +50,28 @@ public function settings() {
   }
 
   /**
-   * Returns the configuration data for the block plugin.
-   *
-   * @return array
-   *   The plugin configuration array from PluginBase::$configuration.
-   *
-   * @todo This doesn't belong here. Move this into a new base class in
-   *   http://drupal.org/node/1764380.
-   * @todo This does not return a config object, so the name is confusing.
-   *
-   * @see \Drupal\Component\Plugin\PluginBase::$configuration
+   * {@inheritdoc}
    */
-  public function getConfig() {
+  public function getConfiguration() {
     return $this->configuration;
   }
 
   /**
-   * Sets a particular value in the block settings.
-   *
-   * @param string $key
-   *   The key of PluginBase::$configuration to set.
-   * @param mixed $value
-   *   The value to set for the provided key.
-   *
-   * @todo This doesn't belong here. Move this into a new base class in
-   *   http://drupal.org/node/1764380.
-   * @todo This does not set a value in config(), so the name is confusing.
-   *
-   * @see \Drupal\Component\Plugin\PluginBase::$configuration
+   * {@inheritdoc}
+   */
+  public function setConfiguration(array $configuration) {
+    $this->configuration = $configuration;
+  }
+
+  /**
+   * {@inheritdoc}
    */
-  public function setConfig($key, $value) {
+  public function setConfigurationValue($key, $value) {
     $this->configuration[$key] = $value;
   }
 
   /**
-   * Indicates whether block-specific criteria allow access to the block.
-   *
-   * Blocks with access restrictions that should always be applied,
-   * regardless of user-configured settings, should implement this method
-   * with that access control logic.
-   *
-   * @return bool
-   *   FALSE to deny access to the block, or TRUE to allow access.
-   *
-   * @see hook_block_access()
+   * {@inheritdoc}
    */
   public function access() {
     // By default, the block is visible unless user-configured rules indicate
@@ -102,7 +80,7 @@ public function access() {
   }
 
   /**
-   * Implements \Drupal\block\BlockPluginInterface::form().
+   * {@inheritdoc}
    *
    * Creates a generic configuration form for all block types. Individual
    * block plugins can add elements to this form by overriding
@@ -111,7 +89,7 @@ public function access() {
    *
    * @see \Drupal\block\BlockBase::blockForm()
    */
-  public function form($form, &$form_state) {
+  public function buildConfigurationForm(array $form, array &$form_state) {
     $definition = $this->getPluginDefinition();
     $form['module'] = array(
       '#type' => 'va