Issue #2857985: Add IgnoreFilter plugin.

src/Plugin/ConfigFilter/IgnoreFilter.php

+<?php
+
+namespace Drupal\config_ignore\Plugin\ConfigFilter;
+
+use Drupal\Component\Utility\Unicode;
+use Drupal\config_filter\Plugin\ConfigFilterBase;
+use Drupal\Core\Config\StorageInterface;
+use Drupal\Core\Plugin\ContainerFactoryPluginInterface;
+use Drupal\Core\Site\Settings;
+use Symfony\Component\DependencyInjection\ContainerInterface;
+
+/**
+ * Provides a ignore filter that reads partly from the active storage.
+ *
+ * @ConfigFilter(
+ *   id = "config_ignore",
+ *   label = "Config Ignore",
+ *   weight = 0
+ * )
+ */
+class IgnoreFilter extends ConfigFilterBase implements ContainerFactoryPluginInterface {
+
+  /**
+   * The active configuration storage.
+   *
+   * @var \Drupal\Core\Config\StorageInterface
+   */
+  protected $active;
+
+  /**
+   * Constructs a new SplitFilter.
+   *
+   * @param array $configuration
+   *   A configuration array containing information about the plugin instance.
+   * @param string $plugin_id
+   *   The plugin_id for the plugin instance.
+   * @param array $plugin_definition
+   *   The plugin implementation definition.
+   * @param \Drupal\Core\Config\StorageInterface $active
+   *   The active configuration store with the configuration on the site.
+   */
+  public function __construct(array $configuration, $plugin_id, $plugin_definition, StorageInterface $active) {
+    parent::__construct($configuration, $plugin_id, $plugin_definition);
+    $this->active = $active;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function create(ContainerInterface $container, array $configuration, $plugin_id, $plugin_definition) {
+    // Get the list of ignored config.
+    $ignored = $container->get('config.factory')->get('config_ignore.settings')->get('ignored_config_entities');
+    // Allow hooks to alter the list.
+    $container->get('module_handler')->invokeAll('config_ignore_settings_alter', [&$ignored]);
+    // Set the list in the plugin configuration.
+    $configuration['ignored'] = $ignored;
+
+    return new static(
+      $configuration,
+      $plugin_id,
+      $plugin_definition,
+      $container->get('config.storage')
+    );
+  }
+
+  /**
+   * Match a config entity name against the list of ignored config entities.
+   *
+   * @param string $config_name
+   *   The name of the config entity to match against all ignored entities.
+   *
+   * @return bool
+   *   True, if the config entity is to be ignored, false otherwise.
+   */
+  protected function matchConfigName($config_name) {
+    if (Settings::get('config_ignore_deactivate')) {
+      // Allow deactivating config_ignore in settings.php. Do not match any name
+      // in that case and allow a normal configuration import to happen.
+      return FALSE;
+    }
+
+    foreach ($this->configuration['ignored'] as $config_ignore_setting) {
+      // Check if the last character in the string is an asterisk.
+      // If so, it means that it is a wildcard.
+      if (Unicode::substr($config_ignore_setting, -1) == '*') {
+        // Remove the asterisk character from the end of the string.
+        $config_ignore_setting = rtrim($config_ignore_setting, '*');
+        // Test if the start of the config, we are checking, are matching
+        // the $config_ignore_setting string. If it is a match, mark
+        // that config name to be ignored.
+        if (Unicode::substr($config_name, 0, strlen($config_ignore_setting)) == $config_ignore_setting) {
+          return TRUE;
+        }
+      }
+      // If string does not contain an asterisk in the end, just compare
+      // the two strings, and if they match, mark that config name to be
+      // ignored.
+      elseif ($config_name == $config_ignore_setting) {
+        return TRUE;
+      }
+    }
+
+    return FALSE;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function filterRead($name, $data) {
+    // Read from the active storage when the name is in the ignored list.
+    if ($this->matchConfigName($name)) {
+      return $this->active->read($name);
+    }
+
+    return $data;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function filterExists($name, $exists) {
+    // A name exists if it is ignored and exists in the active storage.
+    return $exists || ($this->matchConfigName($name) && $this->active->exists($name));
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function filterReadMultiple(array $names, array $data) {
+    // Limit the names which are read from the active storage.
+    $names = array_filter($names, [$this, 'matchConfigName']);
+    $active_data = $this->active->readMultiple($names);
+
+    // Return the data with merged in active data.
+    return array_merge($data, $active_data);
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function filterListAll($prefix, array $data) {
+    $active_names = $this->active->listAll($prefix);
+    // Filter out only ignored config names.
+    $active_names = array_filter($active_names, [$this, 'matchConfigName']);
+
+    // Return the data with the active names which are ignored merged in.
+    return array_unique(array_merge($data, $active_names));
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function filterCreateCollection($collection) {
+    return new static($this->configuration, $this->pluginId, $this->pluginDefinition, $this->active->createCollection($collection));
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function filterGetAllCollectionNames(array $collections) {
+    // Add active collection names as there could be ignored config in them.
+    return array_merge($collections, $this->active->getAllCollectionNames());
+  }
+
+}
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