Drupal 8.0.0 beta 12. More info: https://www.drupal.org/node/2514176

core/modules/language/src/Config/LanguageConfigCollectionNameTrait.php

@@ -0,0 +1,53 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\language\Config\LanguageConfigCollectionNameTrait.
+ */
+
+namespace Drupal\language\Config;
+
+use Drupal\Component\Utility\SafeMarkup;
+
+/**
+ * Provides a common trait for working with language override collection names.
+ */
+trait LanguageConfigCollectionNameTrait {
+
+  /**
+   * Creates a configuration collection name based on a language code.
+   *
+   * @param string $langcode
+   *   The language code.
+   *
+   * @return string
+   *   The configuration collection name for a language code.
+   */
+  protected function createConfigCollectionName($langcode) {
+    return 'language.' . $langcode;
+  }
+
+  /**
+   * Converts a configuration collection name to a language code.
+   *
+   * @param string $collection
+   *   The configuration collection name.
+   *
+   * @return string
+   *   The language code of the collection.
+   *
+   * @throws \InvalidArgumentException
+   *   Exception thrown if the provided collection name is not in the format
+   *   "language.LANGCODE".
+   *
+   * @see self::createConfigCollectionName()
+   */
+  protected function getLangcodeFromCollectionName($collection) {
+    preg_match('/^language\.(.*)$/', $collection, $matches);
+    if (!isset($matches[1])) {
+      throw new \InvalidArgumentException(SafeMarkup::format('!collection is not a valid language override collection', array('!collection' => $collection)));
+    }
+    return $matches[1];
+  }
+
+}