Index: modules/search/search.pages.inc
===================================================================
RCS file: /cvs/drupal/drupal/modules/search/search.pages.inc,v
retrieving revision 1.11
diff -u -r1.11 search.pages.inc
--- modules/search/search.pages.inc	25 Aug 2009 10:27:14 -0000	1.11
+++ modules/search/search.pages.inc	5 Oct 2009 19:48:56 -0000
@@ -10,6 +10,8 @@
  * Menu callback; presents the search form and/or search results.
  */
 function search_view($type = 'node') {
+  global $language;
+
   // Search form submits with POST but redirects to GET. This way we can keep
   // the search query URL clean as a whistle:
   // search/type/keyword+keyword
@@ -29,7 +31,7 @@
       watchdog('search', '%keys (@type).', array('%keys' => $keys, '@type' => module_invoke($type, 'search', 'name')), WATCHDOG_NOTICE, l(t('results'), 'search/' . $type . '/' . $keys));
 
       // Collect the search results:
-      $results = search_data($keys, $type);
+      $results = search_data($keys, $type, $language->language);
 
       // Construct the search form.
       $build['search_form'] = drupal_get_form('search_form', NULL, $keys, $type);
Index: modules/search/search.module
===================================================================
RCS file: /cvs/drupal/drupal/modules/search/search.module,v
retrieving revision 1.318
diff -u -r1.318 search.module
--- modules/search/search.module	21 Sep 2009 06:44:14 -0000	1.318
+++ modules/search/search.module	5 Oct 2009 19:48:56 -0000
@@ -353,8 +353,15 @@
 
 /**
  * Simplifies a string according to indexing rules.
+ *
+ * @param $text
+ *    Text to simplify.
+ * @param $lang
+ *    Language the text is in, e.g. 'de' or 'en-US'; NULL if unknown/multiple.
+ * @return
+ *    Simplified version of $text.
  */
-function search_simplify($text) {
+function search_simplify($text, $lang = NULL) {
   // Decode entities to UTF-8
   $text = decode_entities($text);
 
@@ -362,7 +369,9 @@
   $text = drupal_strtolower($text);
 
   // Call an external processor for word handling.
-  search_invoke_preprocess($text);
+  foreach (module_implements('search_preprocess') as $module) {
+    $text = module_invoke($module, 'search_preprocess', $text, $lang);
+  }
 
   // Simple CJK handling
   if (variable_get('overlap_cjk', TRUE)) {
@@ -418,9 +427,16 @@
 }
 
 /**
- * Splits a string into tokens for indexing.
+ * Preprocesses and splits a string into tokens for indexing.
+ *
+ * @param $text
+ *    Text to simplify.
+ * @param $lang
+ *    Language the text is in, e.g. 'de' or 'en-US'; NULL if unknown/multiple.
+ * @return
+ *    Simplified version of $text.
  */
-function search_index_split($text) {
+function search_index_split($text, $lang = NULL) {
   static $last = NULL;
   static $lastsplit = NULL;
 
@@ -428,7 +444,7 @@
     return $lastsplit;
   }
   // Process words
-  $text = search_simplify($text);
+  $text = search_simplify($text, $lang);
   $words = explode(' ', $text);
   array_walk($words, '_search_index_truncate');
 
@@ -447,29 +463,20 @@
 }
 
 /**
- * Invokes hook_search_preprocess() in modules.
- */
-function search_invoke_preprocess(&$text) {
-  foreach (module_implements('search_preprocess') as $module) {
-    $text = module_invoke($module, 'search_preprocess', $text);
-  }
-}
-
-/**
  * Update the full-text search index for a particular item.
  *
  * @param $sid
  *   A number identifying this particular item (e.g. node id).
- *
  * @param $type
  *   A string defining this type of item (e.g. 'node')
- *
  * @param $text
  *   The content of this item. Must be a piece of HTML text.
+ * @param $lang
+ *    Language the text is in, e.g. 'de' or 'en-US'; NULL if unknown/multiple.
  *
  * @ingroup search
  */
-function search_index($sid, $type, $text) {
+function search_index($sid, $type, $text, $lang = NULL) {
   $minimum_word_size = variable_get('minimum_word_size', 3);
 
   // Link matching
@@ -574,7 +581,7 @@
             $value = $linktitle;
           }
         }
-        $words = search_index_split($value);
+        $words = search_index_split($value, $lang);
         foreach ($words as $word) {
           // Add word to accumulator
           $accum .= $word . ' ';
@@ -953,13 +960,23 @@
 }
 
 /**
- * Perform a standard search on the given keys, and return the formatted results.
+ * Performs a keyword search by invoking hook_search_execute().
+ *
+ * @param $keys
+ *    Keywords being searched for.
+ * @param $type
+ *    Type of search requested.
+ * @param $lang
+ *   The language the keywords are presumed to be in, e.g. 'de' or 'en-US';
+ *   NULL if unknown/multiple.
+ * @return
+ *   Themed and formatted page of search results.
  */
-function search_data($keys = NULL, $type = 'node') {
+function search_data($keys = NULL, $type = 'node', $lang = NULL) {
 
   if (isset($keys)) {
     if (module_hook($type, 'search_execute')) {
-      $results = module_invoke($type, 'search_execute', $keys);
+      $results = module_invoke($type, 'search_execute', $keys, $lang);
       if (isset($results) && is_array($results) && count($results)) {
         if (module_hook($type, 'search_page')) {
           return module_invoke($type, 'search_page', $results);
Index: modules/search/search.extender.inc
===================================================================
RCS file: /cvs/drupal/drupal/modules/search/search.extender.inc,v
retrieving revision 1.1
diff -u -r1.1 search.extender.inc
--- modules/search/search.extender.inc	29 Aug 2009 12:43:18 -0000	1.1
+++ modules/search/search.extender.inc	5 Oct 2009 19:48:56 -0000
@@ -122,18 +122,33 @@
   protected $multiply = array();
 
   /**
+   * Language of search terms, e.g. 'de' or 'en-US'; NULL if unknown.
+   *
+   * This is passed to search_simplify() for language-specific preprocessing
+   * of keywords.
+   *
+   * @var string
+   */
+  protected $term_lang = NULL;
+
+  /**
    * Search items for the given search query string and type.
    *
    * @param $query
    *   A search query string, that can contain options.
    * @param $type
    *   The type of search, this maps to {search_index}.type.
+   * @param $lang
+   *   Language the search terms are in, e.g. 'de' or 'en-US'; NULL if
+   *   unknown/multiple. This is only used for language-specific preprocessing
+   *   of keywords in the search query.
    * @return
    *   The SearchQuery object.
    */
-  public function searchExpression($expression, $type) {
+  public function searchExpression($expression, $type, $lang = NULL) {
     $this->searchExpression = $expression;
     $this->type = $type;
+    $this->term_lang = $lang;
 
     return $this;
   }
@@ -188,8 +203,9 @@
         $phrase = TRUE;
         $this->simple = FALSE;
       }
-      // Simplify keyword according to indexing rules and external preprocessors.
-      $words = search_simplify($match[2]);
+      // Simplify keyword according to indexing rules and external
+      // preprocessors.
+      $words = search_simplify($match[2], $this->term_lang);
       // Re-explode in case simplification added more words, except when
       // matching a phrase.
       $words = $phrase ? array($words) : preg_split('/ /', $words, -1, PREG_SPLIT_NO_EMPTY);
Index: modules/search/search.api.php
===================================================================
RCS file: /cvs/drupal/drupal/modules/search/search.api.php,v
retrieving revision 1.16
diff -u -r1.16 search.api.php
--- modules/search/search.api.php	18 Sep 2009 00:12:47 -0000	1.16
+++ modules/search/search.api.php	5 Oct 2009 19:48:56 -0000
@@ -14,20 +14,16 @@
 /**
  * Define a custom search routine.
  *
- * This hook allows a module to perform searches on content it defines
- * (custom node types, users, or comments, for example) when a site search
- * is performed. 
- *
- * Note that you can use form API to extend the search. You will need to use
- * hook_form_alter() to add any additional required form elements. You can
- * process their values on submission using a custom validation function.
- * You will need to merge any custom search values into the search keys
- * using a key:value syntax. This allows all search queries to have a clean
- * and permanent URL. See node_form_search_form_alter() for an example.
- *
- * The example given here is for node.module, which uses the indexed search
- * capabilities. To do this, node module also implements hook_update_index()
- * which is used to create and maintain the index.
+ * This hook allows a module to tell search.module that it wishes to
+ * perform searches on content it defines (custom node types, users, or
+ * comments, for example) when a site search is performed.
+ *
+ * In order for the search to do anything, your module must also implement
+ * hook_search_execute(), which is called when someone requests a search
+ * on your module's type of content. If you want to have your content
+ * indexed in the standard search index, your module should also implement
+ * hook_update_index(). If your search type has settings, you can implement
+ * hook_search_admin() to add them to the search settings page.
  *
  * @return
  *   Array with the optional keys 'title' for the tab title and 'path' for
@@ -46,7 +42,7 @@
 /**
  * Define access to a custom search routine.
  *
- * This hook allows a module to deny access to a user to a search tab.
+ * This hook allows a module to define permissions for a search tab.
  *
  * @ingroup search
  */
@@ -55,9 +51,9 @@
 }
 
 /**
- * The search index is going to be rebuilt.
+ * Take action when the search index is going to be rebuilt.
  *
- * Modules which use  hook_update_index() should update their indexing
+ * Modules which use hook_update_index() should update their indexing
  * bookkeeping so that it starts from scratch the next time
  * hook_update_index() is called.
  *
@@ -71,7 +67,7 @@
 }
 
 /**
- * Report the stutus of indexing.
+ * Report the status of indexing.
  *
  * @return
  *  An associative array with the key-value pairs:
@@ -87,10 +83,10 @@
 }
 
 /**
- * Add elements to the search administration form.
+ * Add elements to the search settings page.
  *
  * @return
- *   The form array for the Search settings page at admin/config/search/settings.
+ *   Form array for the Search settings page at admin/config/search/settings.
  *
  * @ingroup search
  */
@@ -121,11 +117,22 @@
 /**
  * Execute a search for a set of key words.
  *
- * We call do_search() with the keys, the module name, and extra SQL fragments
- * to use when searching. See hook_update_index() for more information.
+ * Use the database API with the SearchQuery extender to perform the
+ * search, if your module uses the built-in search index (see
+ * hook_update_index() for information on how to use the index).
+ *
+ * Note that you can use form API to extend the search. You will need to use
+ * hook_form_alter() to add any additional required form elements. You can
+ * process their values on submission using a custom validation function.
+ * You will need to merge any custom search values into the search keys
+ * using a key:value syntax. This allows all search queries to have a clean
+ * and permanent URL. See node_form_search_form_alter() for an example.
  *
  * @param $keys
  *   The search keywords as entered by the user.
+ * @param $lang
+ *   The language the keywords are presumed to be in, e.g. 'de' or 'en-US';
+ *   NULL if unknown/multiple.
  *
  * @return
  *   An array of search results. To use the default search result
@@ -141,14 +148,14 @@
  *
  * @ingroup search
  */
-function hook_search_execute($keys = NULL) {
+function hook_search_execute($keys = NULL, $lang = NULL) {
   // Build matching conditions
   $query = db_search()->extend('PagerDefault');
   $query->join('node', 'n', 'n.nid = i.sid');
   $query
     ->condition('n.status', 1)
     ->addTag('node_access')
-    ->searchExpression($keys, 'node');
+    ->searchExpression($keys, 'node', $lang);
 
   // Insert special keywords.
   $query->setOption('type', 'n.type');
@@ -204,34 +211,47 @@
 }
 
 /**
- * Preprocess text for the search index.
+ * Preprocess text for search.
  *
- * This hook is called both for text added to the search index, as well as
+ * This hook is called to preprocess both the text added to the search index and
  * the keywords users have submitted for searching.
  *
- * This is required for example to allow Japanese or Chinese text to be
- * searched. As these languages do not use spaces, it needs to be split into
- * separate words before it can be indexed. There are various external
- * libraries for this.
+ * Possible uses:
+ * - Adding spaces between words of Chinese or Japanese text.
+ * - Stemming words down to their root words to allow matches between, for
+ *   instance, walk, walked, walking, and walks in searching.
+ * - Expanding abbreviations and acronymns that occur in text.
  *
  * @param $text
- *   The text to split. This is a single piece of plain-text that was
- *   extracted from between two HTML tags. Will not contain any HTML entities.
+ *   The text to preprocess. This is a single piece of plain text extracted
+ *   from between two HTML tags or from the search query. It will not contain
+ *   any HTML entities or HTML tags.
+ * @param $lang
+ *    Language the text is in, e.g. 'de' or 'en-US'; NULL if unknown/multiple.
  * @return
- *   The text after processing.
+ *   The text after preprocessing. Note that if your module decides not to alter
+ *   the text, it should return the original text. Also, after preprocessing,
+ *   words in the text should be separated by a space.
  *
  * @ingroup search
  */
-function hook_search_preprocess($text) {
-  // Do processing on $text
+function hook_search_preprocess($text, $lang = NULL) {
+  // Check the language
+  if (!is_null( $lang ) && $lang != 'en') {
+    // Not a language we want to preprocess
+    return $text;
+  }
+
+  // Do some processing on $text
+
   return $text;
 }
 
 /**
- * Update Drupal's full-text index for this module.
+ * Update the search index for this module.
  *
- * Modules can implement this hook if they want to use the full-text indexing
- * mechanism in Drupal.
+ * Modules can implement this hook if they want to use the built-in full-text
+ * search index to perform searches.
  *
  * This hook is called every cron run if search.module is enabled. A module
  * should check which of its items were modified or added since the last
@@ -276,7 +296,7 @@
     }
 
     // Update index
-    search_index($node->nid, 'node', $text);
+    search_index($node->nid, 'node', $text, $node->language);
   }
 }
 /**
Index: modules/user/user.module
===================================================================
RCS file: /cvs/drupal/drupal/modules/user/user.module,v
retrieving revision 1.1055
diff -u -r1.1055 user.module
--- modules/user/user.module	2 Oct 2009 14:49:10 -0000	1.1055
+++ modules/user/user.module	5 Oct 2009 19:48:56 -0000
@@ -798,7 +798,7 @@
 /**
  * Implement hook_search_execute().
  */
-function user_search_execute($keys = NULL) {
+function user_search_execute($keys = NULL, $lang = NULL) {
   $find = array();
   // Replace wildcards with MySQL/PostgreSQL wildcards.
   $keys = preg_replace('!\*+!', '%', $keys);
Index: modules/node/node.module
===================================================================
RCS file: /cvs/drupal/drupal/modules/node/node.module,v
retrieving revision 1.1139
diff -u -r1.1139 node.module
--- modules/node/node.module	5 Oct 2009 01:18:25 -0000	1.1139
+++ modules/node/node.module	5 Oct 2009 19:48:56 -0000
@@ -1362,14 +1362,28 @@
 /**
  * Implement hook_search_execute().
  */
-function node_search_execute($keys = NULL) {
+function node_search_execute($keys = NULL, $lang = NULL) {
   // Build matching conditions
   $query = db_select('search_index', 'i')->extend('SearchQuery')->extend('PagerDefault');
   $query->join('node', 'n', 'n.nid = i.sid');
+
+  // Override the language passed in if the user specified language.
+  $tmp_lang = search_expression_extract($keys, 'language');
+  if ($tmp_lang) {
+    if (strpos( $tmp_lang, ',') !== FALSE) {
+      // multiple selection
+      $lang = NULL;
+    }
+    else {
+      // single selection
+      $lang = $tmp_lang;
+    }
+  }
+
   $query
     ->condition('n.status', 1)
     ->addTag('node_access')
-    ->searchExpression($keys, 'node');
+    ->searchExpression($keys, 'node', $lang);
   
   // Insert special keywords.
   $query->setOption('type', 'n.type');
@@ -2028,7 +2042,7 @@
   }
 
   // Update index
-  search_index($node->nid, 'node', $text);
+  search_index($node->nid, 'node', $text, $node->language);
 }
 
 /**