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root / drupal7 / includes / language.inc @ 96ad5adc

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<?php
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/**
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 * @file
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 * Language Negotiation API.
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 *
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 * @see http://drupal.org/node/1497272
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 */
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/**
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 * No language negotiation. The default language is used.
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 */
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define('LANGUAGE_NEGOTIATION_DEFAULT', 'language-default');
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/**
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 * @defgroup language_negotiation Language Negotiation API functionality
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 * @{
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 * Functions to customize the language types and the negotiation process.
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 *
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 * The language negotiation API is based on two major concepts:
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 * - Language types: types of translatable data (the types of data that a user
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 *   can view or request).
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 * - Language negotiation providers: functions for determining which language to
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 *   use to present a particular piece of data to the user.
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 * Both language types and language negotiation providers are customizable.
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 *
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 * Drupal defines three built-in language types:
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 * - Interface language: The page's main language, used to present translated
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 *   user interface elements such as titles, labels, help text, and messages.
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 * - Content language: The language used to present content that is available
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 *   in more than one language (see
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 *   @link field_language Field Language API @endlink for details).
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 * - URL language: The language associated with URLs. When generating a URL,
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 *   this value will be used by url() as a default if no explicit preference is
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 *   provided.
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 * Modules can define additional language types through
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 * hook_language_types_info(), and alter existing language type definitions
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 * through hook_language_types_info_alter().
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 *
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 * Language types may be configurable or fixed. The language negotiation
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 * providers associated with a configurable language type can be explicitly
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 * set through the user interface. A fixed language type has predetermined
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 * (module-defined) language negotiation settings and, thus, does not appear in
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 * the configuration page. Here is a code snippet that makes the content
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 * language (which by default inherits the interface language's values)
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 * configurable:
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 * @code
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 * function mymodule_language_types_info_alter(&$language_types) {
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 *   unset($language_types[LANGUAGE_TYPE_CONTENT]['fixed']);
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 * }
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 * @endcode
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 *
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 * Every language type can have a different set of language negotiation
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 * providers assigned to it. Different language types often share the same
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 * language negotiation settings, but they can have independent settings if
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 * needed. If two language types are configured the same way, their language
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 * switcher configuration will be functionally identical and the same settings
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 * will act on both language types.
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 *
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 * Drupal defines the following built-in language negotiation providers:
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 * - URL: Determine the language from the URL (path prefix or domain).
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 * - Session: Determine the language from a request/session parameter.
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 * - User: Follow the user's language preference.
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 * - Browser: Determine the language from the browser's language settings.
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 * - Default language: Use the default site language.
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 * Language negotiation providers are simple callback functions that implement a
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 * particular logic to return a language code. For instance, the URL provider
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 * searches for a valid path prefix or domain name in the current request URL.
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 * If a language negotiation provider does not return a valid language code, the
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 * next provider associated to the language type (based on provider weight) is
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 * invoked.
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 *
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 * Modules can define additional language negotiation providers through
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 * hook_language_negotiation_info(), and alter existing providers through
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 * hook_language_negotiation_info_alter(). Here is an example snippet that lets
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 * path prefixes be ignored for administrative paths:
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 * @code
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 * function mymodule_language_negotiation_info_alter(&$negotiation_info) {
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 *   // Replace the core function with our own function.
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 *   module_load_include('language', 'inc', 'language.negotiation');
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 *   $negotiation_info[LANGUAGE_NEGOTIATION_URL]['callbacks']['language'] = 'mymodule_from_url';
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 *   $negotiation_info[LANGUAGE_NEGOTIATION_URL]['file'] = drupal_get_path('module', 'mymodule') . '/mymodule.module';
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 * }
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 *
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 * function mymodule_from_url($languages) {
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 *   // Use the core URL language negotiation provider to get a valid language
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 *   // code.
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 *   module_load_include('language', 'inc', 'language.negotiation');
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 *   $langcode = language_from_url($languages);
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 *
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 *   // If we are on an administrative path, override with the default language.
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 *   if (isset($_GET['q']) && strtok($_GET['q'], '/') == 'admin') {
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 *     return language_default()->langcode;
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 *   }
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 *   return $langcode;
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 * }
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 * @endcode
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 *
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 * For more information, see
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 * @link http://drupal.org/node/1497272 Language Negotiation API @endlink
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 */
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/**
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 * Returns all the defined language types.
105
 *
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 * @return
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 *   An array of language type names. The name will be used as the global
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 *   variable name the language value will be stored in.
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 */
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function language_types_info() {
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  $language_types = &drupal_static(__FUNCTION__);
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  if (!isset($language_types)) {
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    $language_types = module_invoke_all('language_types_info');
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    // Let other modules alter the list of language types.
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    drupal_alter('language_types_info', $language_types);
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  }
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  return $language_types;
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}
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/**
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 * Returns only the configurable language types.
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 *
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 * A language type maybe configurable or fixed. A fixed language type is a type
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 * whose language negotiation providers are module-defined and not altered
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 * through the user interface.
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 *
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 * @param $stored
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 *   Optional. By default retrieves values from the 'language_types' variable to
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 *   avoid unnecessary hook invocations.
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 *   If set to FALSE retrieves values from the actual language type definitions.
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 *   This allows to react to alterations performed on the definitions by modules
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 *   installed after the 'language_types' variable is set.
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 *
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 * @return
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 *   An array of language type names.
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 */
139
function language_types_configurable($stored = TRUE) {
140
  $configurable = &drupal_static(__FUNCTION__);
141

    
142
  if ($stored && !isset($configurable)) {
143
    $types = variable_get('language_types', drupal_language_types());
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    $configurable = array_keys(array_filter($types));
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  }
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  if (!$stored) {
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    $result = array();
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    foreach (language_types_info() as $type => $info) {
150
      if (!isset($info['fixed'])) {
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        $result[] = $type;
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      }
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    }
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    return $result;
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  }
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  return $configurable;
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}
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/**
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 * Disables the given language types.
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 *
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 * @param $types
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 *   An array of language types.
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 */
166
function language_types_disable($types) {
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  $enabled_types = variable_get('language_types', drupal_language_types());
168

    
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  foreach ($types as $type) {
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    unset($enabled_types[$type]);
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  }
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  variable_set('language_types', $enabled_types);
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}
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/**
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 * Updates the language type configuration.
178
 */
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function language_types_set() {
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  // Ensure that we are getting the defined language negotiation information. An
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  // invocation of module_enable() or module_disable() could outdate the cached
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  // information.
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  drupal_static_reset('language_types_info');
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  drupal_static_reset('language_negotiation_info');
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  // Determine which language types are configurable and which not by checking
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  // whether the 'fixed' key is defined. Non-configurable (fixed) language types
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  // have their language negotiation settings stored there.
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  $defined_providers = language_negotiation_info();
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  foreach (language_types_info() as $type => $info) {
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    if (isset($info['fixed'])) {
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      $language_types[$type] = FALSE;
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      $negotiation = array();
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      foreach ($info['fixed'] as $weight => $id) {
195
        if (isset($defined_providers[$id])) {
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          $negotiation[$id] = $weight;
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        }
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      }
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      language_negotiation_set($type, $negotiation);
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    }
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    else {
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      $language_types[$type] = TRUE;
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    }
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  }
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  // Save language types.
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  variable_set('language_types', $language_types);
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  // Ensure that subsequent calls of language_types_configurable() return the
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  // updated language type information.
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  drupal_static_reset('language_types_configurable');
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}
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/**
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 * Checks whether a language negotiation provider is enabled for a language type.
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 *
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 * This has two possible behaviors:
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 *  - If $provider_id is given return its ID if enabled, FALSE otherwise.
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 *  - If no ID is passed the first enabled language negotiation provider is
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 *    returned.
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 *
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 * @param $type
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 *   The language negotiation provider type.
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 * @param $provider_id
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 *   The language negotiation provider ID.
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 *
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 * @return
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 *   The provider ID if it is enabled, FALSE otherwise.
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 */
230
function language_negotiation_get($type, $provider_id = NULL) {
231
  $negotiation = variable_get("language_negotiation_$type", array());
232

    
233
  if (empty($negotiation)) {
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    return empty($provider_id) ? LANGUAGE_NEGOTIATION_DEFAULT : FALSE;
235
  }
236

    
237
  if (empty($provider_id)) {
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    return key($negotiation);
239
  }
240

    
241
  if (isset($negotiation[$provider_id])) {
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    return $provider_id;
243
  }
244

    
245
  return FALSE;
246
}
247

    
248
/**
249
 * Checks if the language negotiation provider is enabled for any language type.
250
 *
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 * @param $provider_id
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 *   The language negotiation provider ID.
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 *
254
 * @return
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 *   TRUE if there is at least one language type for which the given language
256
 *   provider is enabled, FALSE otherwise.
257
 */
258
function language_negotiation_get_any($provider_id) {
259
  foreach (language_types_configurable() as $type) {
260
    if (language_negotiation_get($type, $provider_id)) {
261
      return TRUE;
262
    }
263
  }
264

    
265
  return FALSE;
266
}
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268
/**
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 * Returns the language switch links for the given language.
270
 *
271
 * @param $type
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 *   The language negotiation type.
273
 * @param $path
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 *   The internal path the switch links will be relative to.
275
 *
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 * @return
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 *   A keyed array of links ready to be themed.
278
 */
279
function language_negotiation_get_switch_links($type, $path) {
280
  $links = FALSE;
281
  $negotiation = variable_get("language_negotiation_$type", array());
282

    
283
  // Only get the languages if we have more than one.
284
  if (count(language_list()) >= 2) {
285
    $language = language_initialize($type);
286
  }
287

    
288
  foreach ($negotiation as $id => $provider) {
289
    if (isset($provider['callbacks']['switcher'])) {
290
      if (isset($provider['file'])) {
291
        require_once DRUPAL_ROOT . '/' . $provider['file'];
292
      }
293

    
294
      $callback = $provider['callbacks']['switcher'];
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      $result = $callback($type, $path);
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297
      // Add support for WCAG 2.0's Language of Parts to add language identifiers.
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      // http://www.w3.org/TR/UNDERSTANDING-WCAG20/meaning-other-lang-id.html
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      foreach ($result as $langcode => $link) {
300
        $result[$langcode]['attributes']['xml:lang'] = $langcode;
301
      }
302

    
303
      if (!empty($result)) {
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        // Allow modules to provide translations for specific links.
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        drupal_alter('language_switch_links', $result, $type, $path);
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        $links = (object) array('links' => $result, 'provider' => $id);
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        break;
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      }
309
    }
310
  }
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312
  return $links;
313
}
314

    
315
/**
316
 * Removes any unused language negotiation providers from the configuration.
317
 */
318
function language_negotiation_purge() {
319
  // Ensure that we are getting the defined language negotiation information. An
320
  // invocation of module_enable() or module_disable() could outdate the cached
321
  // information.
322
  drupal_static_reset('language_negotiation_info');
323
  drupal_static_reset('language_types_info');
324

    
325
  $defined_providers = language_negotiation_info();
326
  foreach (language_types_info() as $type => $type_info) {
327
    $weight = 0;
328
    $negotiation = array();
329
    foreach (variable_get("language_negotiation_$type", array()) as $id => $provider) {
330
      if (isset($defined_providers[$id])) {
331
        $negotiation[$id] = $weight++;
332
      }
333
    }
334
    language_negotiation_set($type, $negotiation);
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  }
336
}
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338
/**
339
 * Saves a list of language negotiation providers.
340
 *
341
 * @param $type
342
 *   The language negotiation type.
343
 * @param $language_providers
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 *   An array of language negotiation provider weights keyed by provider ID.
345
 *   @see language_provider_weight()
346
 */
347
function language_negotiation_set($type, $language_providers) {
348
  // Save only the necessary fields.
349
  $provider_fields = array('callbacks', 'file', 'cache');
350

    
351
  $negotiation = array();
352
  $providers_weight = array();
353
  $defined_providers = language_negotiation_info();
354
  $default_types = language_types_configurable(FALSE);
355

    
356
  // Initialize the providers weight list.
357
  foreach ($language_providers as $id => $provider) {
358
    $providers_weight[$id] = language_provider_weight($provider);
359
  }
360

    
361
  // Order providers list by weight.
362
  asort($providers_weight);
363

    
364
  foreach ($providers_weight as $id => $weight) {
365
    if (isset($defined_providers[$id])) {
366
      $provider = $defined_providers[$id];
367
      // If the provider does not express any preference about types, make it
368
      // available for any configurable type.
369
      $types = array_flip(isset($provider['types']) ? $provider['types'] : $default_types);
370
      // Check whether the provider is defined and has the right type.
371
      if (isset($types[$type])) {
372
        $provider_data = array();
373
        foreach ($provider_fields as $field) {
374
          if (isset($provider[$field])) {
375
            $provider_data[$field] = $provider[$field];
376
          }
377
        }
378
        $negotiation[$id] = $provider_data;
379
      }
380
    }
381
  }
382

    
383
  variable_set("language_negotiation_$type", $negotiation);
384
}
385

    
386
/**
387
 * Returns all the defined language negotiation providers.
388
 *
389
 * @return
390
 *   An array of language negotiation providers.
391
 */
392
function language_negotiation_info() {
393
  $language_providers = &drupal_static(__FUNCTION__);
394

    
395
  if (!isset($language_providers)) {
396
    // Collect all the module-defined language negotiation providers.
397
    $language_providers = module_invoke_all('language_negotiation_info');
398

    
399
    // Add the default language negotiation provider.
400
    $language_providers[LANGUAGE_NEGOTIATION_DEFAULT] = array(
401
      'callbacks' => array('language' => 'language_from_default'),
402
      'weight' => 10,
403
      'name' => t('Default'),
404
      'description' => t('Use the default site language (@language_name).', array('@language_name' => language_default()->native)),
405
    );
406

    
407
    // Let other modules alter the list of language negotiation providers.
408
    drupal_alter('language_negotiation_info', $language_providers);
409
  }
410

    
411
  return $language_providers;
412
}
413

    
414
/**
415
 * Helper function used to cache the language negotiation providers results.
416
 *
417
 * @param $provider_id
418
 *   The language negotiation provider's identifier.
419
 * @param $provider
420
 *   (optional) An associative array of information about the provider to be
421
 *   invoked (see hook_language_negotiation_info() for details). If not passed
422
 *   in, it will be loaded through language_negotiation_info().
423
 *
424
 * @return
425
 *   A language object representing the language chosen by the provider.
426
 */
427
function language_provider_invoke($provider_id, $provider = NULL) {
428
  $results = &drupal_static(__FUNCTION__);
429

    
430
  if (!isset($results[$provider_id])) {
431
    global $user;
432

    
433
    // Get languages grouped by status and select only the enabled ones.
434
    $languages = language_list('enabled');
435
    $languages = $languages[1];
436

    
437
    if (!isset($provider)) {
438
      $providers = language_negotiation_info();
439
      $provider = $providers[$provider_id];
440
    }
441

    
442
    if (isset($provider['file'])) {
443
      require_once DRUPAL_ROOT . '/' . $provider['file'];
444
    }
445

    
446
    // If the language negotiation provider has no cache preference or this is
447
    // satisfied we can execute the callback.
448
    $cache = !isset($provider['cache']) || $user->uid || $provider['cache'] == variable_get('cache', 0);
449
    $callback = isset($provider['callbacks']['language']) ? $provider['callbacks']['language'] : FALSE;
450
    $langcode = $cache && function_exists($callback) ? $callback($languages) : FALSE;
451
    $results[$provider_id] = isset($languages[$langcode]) ? $languages[$langcode] : FALSE;
452
  }
453

    
454
  // Since objects are resources, we need to return a clone to prevent the
455
  // language negotiation provider cache from being unintentionally altered. The
456
  // same providers might be used with different language types based on
457
  // configuration.
458
  return !empty($results[$provider_id]) ? clone($results[$provider_id]) : $results[$provider_id];
459
}
460

    
461
/**
462
 * Returns the passed language negotiation provider weight or a default value.
463
 *
464
 * @param $provider
465
 *   A language negotiation provider data structure.
466
 *
467
 * @return
468
 *   A numeric weight.
469
 */
470
function language_provider_weight($provider) {
471
  $default = is_numeric($provider) ? $provider : 0;
472
  return isset($provider['weight']) && is_numeric($provider['weight']) ? $provider['weight'] : $default;
473
}
474

    
475
/**
476
 * Chooses a language based on language negotiation provider settings.
477
 *
478
 * @param $type
479
 *   The language type key to find the language for.
480
 *
481
 * @return
482
 *   The negotiated language object.
483
 */
484
function language_initialize($type) {
485
  // Execute the language negotiation providers in the order they were set up and return the
486
  // first valid language found.
487
  $negotiation = variable_get("language_negotiation_$type", array());
488

    
489
  foreach ($negotiation as $provider_id => $provider) {
490
    $language = language_provider_invoke($provider_id, $provider);
491
    if ($language) {
492
      $language->provider = $provider_id;
493
      return $language;
494
    }
495
  }
496

    
497
  // If no other language was found use the default one.
498
  $language = language_default();
499
  $language->provider = LANGUAGE_NEGOTIATION_DEFAULT;
500
  return $language;
501
}
502

    
503
/**
504
 * Returns the default language negotiation provider.
505
 *
506
 * @return
507
 *   The default language code.
508
 */
509
function language_from_default() {
510
  return language_default()->language;
511
}
512

    
513
/**
514
 * Splits the given path into prefix and actual path.
515
 *
516
 * Parse the given path and return the language object identified by the prefix
517
 * and the actual path.
518
 *
519
 * @param $path
520
 *   The path to split.
521
 * @param $languages
522
 *   An array of valid languages.
523
 *
524
 * @return
525
 *   An array composed of:
526
 *    - A language object corresponding to the identified prefix on success,
527
 *      FALSE otherwise.
528
 *    - The path without the prefix on success, the given path otherwise.
529
 */
530
function language_url_split_prefix($path, $languages) {
531
  $args = empty($path) ? array() : explode('/', $path);
532
  $prefix = array_shift($args);
533

    
534
  // Search prefix within enabled languages.
535
  foreach ($languages as $language) {
536
    if (!empty($language->prefix) && $language->prefix == $prefix) {
537
      // Rebuild $path with the language removed.
538
      return array($language, implode('/', $args));
539
    }
540
  }
541

    
542
  return array(FALSE, $path);
543
}
544

    
545
/**
546
 * Returns the possible fallback languages ordered by language weight.
547
 *
548
 * @param
549
 *   (optional) The language type. Defaults to LANGUAGE_TYPE_CONTENT.
550
 *
551
 * @return
552
 *   An array of language codes.
553
 */
554
function language_fallback_get_candidates($type = LANGUAGE_TYPE_CONTENT) {
555
  $fallback_candidates = &drupal_static(__FUNCTION__);
556

    
557
  if (!isset($fallback_candidates)) {
558
    $fallback_candidates = array();
559

    
560
    // Get languages ordered by weight.
561
    // Use array keys to avoid duplicated entries.
562
    foreach (language_list('weight') as $languages) {
563
      foreach ($languages as $language) {
564
        $fallback_candidates[$language->language] = NULL;
565
      }
566
    }
567

    
568
    $fallback_candidates = array_keys($fallback_candidates);
569
    $fallback_candidates[] = LANGUAGE_NONE;
570

    
571
    // Let other modules hook in and add/change candidates.
572
    drupal_alter('language_fallback_candidates', $fallback_candidates);
573
  }
574

    
575
  return $fallback_candidates;
576
}
577

    
578
/**
579
 * @} End of "language_negotiation"
580
 */