diff -r 07239de796bb -r e756a8c72c3d cms/drupal/modules/system/language.api.php
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/cms/drupal/modules/system/language.api.php	Fri Sep 08 12:04:06 2017 +0200
@@ -0,0 +1,186 @@
+<?php
+
+/**
+ * @file
+ * Hooks provided by the base system for language support.
+ */
+
+/**
+ * @addtogroup hooks
+ * @{
+ */
+
+/**
+ * Allows modules to act after language initialization has been performed.
+ *
+ * This is primarily needed to provide translation for configuration variables
+ * in the proper bootstrap phase. Variables are user-defined strings and
+ * therefore should not be translated via t(), since the source string can
+ * change without notice and any previous translation would be lost. Moreover,
+ * since variables can be used in the bootstrap phase, we need a bootstrap hook
+ * to provide a translation early enough to avoid misalignments between code
+ * using the original values and code using the translated values. However
+ * modules implementing hook_boot() should be aware that language initialization
+ * did not happen yet and thus they cannot rely on translated variables.
+ */
+function hook_language_init() {
+  global $language, $conf;
+
+  switch ($language->language) {
+    case 'it':
+      $conf['site_name'] = 'Il mio sito Drupal';
+      break;
+
+    case 'fr':
+      $conf['site_name'] = 'Mon site Drupal';
+      break;
+  }
+}
+
+/**
+ * Perform alterations on language switcher links.
+ *
+ * A language switcher link may need to point to a different path or use a
+ * translated link text before going through l(), which will just handle the
+ * path aliases.
+ *
+ * @param $links
+ *   Nested array of links keyed by language code.
+ * @param $type
+ *   The language type the links will switch.
+ * @param $path
+ *   The current path.
+ */
+function hook_language_switch_links_alter(array &$links, $type, $path) {
+  global $language;
+
+  if ($type == LANGUAGE_TYPE_CONTENT && isset($links[$language->language])) {
+    foreach ($links[$language->language] as $link) {
+      $link['attributes']['class'][] = 'active-language';
+    }
+  }
+}
+
+/**
+ * Define language types.
+ *
+ * @return
+ *   An associative array of language type definitions. The keys are the
+ *   identifiers, which are also used as names for global variables representing
+ *   the types in the bootstrap phase. The values are associative arrays that
+ *   may contain the following elements:
+ *   - name: The human-readable language type identifier.
+ *   - description: A description of the language type.
+ *   - fixed: A fixed array of language negotiation provider identifiers to use
+ *     to initialize this language. Defining this key makes the language type
+ *     non-configurable, so it will always use the specified providers in the
+ *     given priority order. Omit to make the language type configurable.
+ *
+ * @see hook_language_types_info_alter()
+ * @ingroup language_negotiation
+ */
+function hook_language_types_info() {
+  return array(
+    'custom_language_type' => array(
+      'name' => t('Custom language'),
+      'description' => t('A custom language type.'),
+    ),
+    'fixed_custom_language_type' => array(
+      'fixed' => array('custom_language_provider'),
+    ),
+  );
+}
+
+/**
+ * Perform alterations on language types.
+ *
+ * @param $language_types
+ *   Array of language type definitions.
+ *
+ * @see hook_language_types_info()
+ * @ingroup language_negotiation
+ */
+function hook_language_types_info_alter(array &$language_types) {
+  if (isset($language_types['custom_language_type'])) {
+    $language_types['custom_language_type_custom']['description'] = t('A far better description.');
+  }
+}
+
+/**
+ * Define language negotiation providers.
+ *
+ * @return
+ *   An associative array of language negotiation provider definitions. The keys
+ *   are provider identifiers, and the values are associative arrays defining
+ *   each provider, with the following elements:
+ *   - types: An array of allowed language types. If a language negotiation
+ *     provider does not specify which language types it should be used with, it
+ *     will be available for all the configurable language types.
+ *   - callbacks: An associative array of functions that will be called to
+ *     perform various tasks. Possible elements are:
+ *     - language: (required) Name of the callback function that determines the
+ *       language value.
+ *     - switcher: (optional) Name of the callback function that determines
+ *       links for a language switcher block associated with this provider. See
+ *       language_switcher_url() for an example.
+ *     - url_rewrite: (optional) Name of the callback function that provides URL
+ *       rewriting, if needed by this provider.
+ *   - file: The file where callback functions are defined (this file will be
+ *     included before the callbacks are invoked).
+ *   - weight: The default weight of the provider.
+ *   - name: The translated human-readable name for the provider.
+ *   - description: A translated longer description of the provider.
+ *   - config: An internal path pointing to the provider's configuration page.
+ *   - cache: The value Drupal's page cache should be set to for the current
+ *     provider to be invoked.
+ *
+ * @see hook_language_negotiation_info_alter()
+ * @ingroup language_negotiation
+ */
+function hook_language_negotiation_info() {
+  return array(
+    'custom_language_provider' => array(
+      'callbacks' => array(
+        'language' => 'custom_language_provider_callback',
+        'switcher' => 'custom_language_switcher_callback',
+        'url_rewrite' => 'custom_language_url_rewrite_callback',
+      ),
+      'file' => drupal_get_path('module', 'custom') . '/custom.module',
+      'weight' => -4,
+      'types' => array('custom_language_type'),
+      'name' => t('Custom language negotiation provider'),
+      'description' => t('This is a custom language negotiation provider.'),
+      'cache' => 0,
+    ),
+  );
+}
+
+/**
+ * Perform alterations on language negoiation providers.
+ *
+ * @param $language_providers
+ *   Array of language negotiation provider definitions.
+ *
+ * @see hook_language_negotiation_info()
+ * @ingroup language_negotiation
+ */
+function hook_language_negotiation_info_alter(array &$language_providers) {
+  if (isset($language_providers['custom_language_provider'])) {
+    $language_providers['custom_language_provider']['config'] = 'admin/config/regional/language/configure/custom-language-provider';
+  }
+}
+
+/**
+ * Perform alterations on the language fallback candidates.
+ *
+ * @param $fallback_candidates
+ *   An array of language codes whose order will determine the language fallback
+ *   order.
+ */
+function hook_language_fallback_candidates_alter(array &$fallback_candidates) {
+  $fallback_candidates = array_reverse($fallback_candidates);
+}
+
+/**
+ * @} End of "addtogroup hooks".
+ */