Improved search for terms < ft_min_word_len

diff --git a/wcfsetup/install/files/lib/system/search/SearchEngine.class.php b/wcfsetup/install/files/lib/system/search/SearchEngine.class.php
index e3270c10606ad01c1d42e0478a57d84505c6830a..45b5b46f101d451b2bea6ee12a73036f261c99bc 100644 (file)
--- a/wcfsetup/install/files/lib/system/search/SearchEngine.class.php
+++ b/wcfsetup/install/files/lib/system/search/SearchEngine.class.php
@@ -2,6 +2,7 @@
 namespace wcf\system\search;
 use wcf\data\object\type\ObjectTypeCache;
 use wcf\system\database\util\PreparedStatementConditionBuilder;
+use wcf\system\database\DatabaseException;
 use wcf\system\exception\SystemException;
 use wcf\system\SingletonFactory;
 use wcf\system\WCF;
@@ -11,7 +12,7 @@ use wcf\util\StringUtil;
  * SearchEngine searches for given query in the selected object types.
  * 
  * @author     Marcel Werk
- * @copyright  2001-2013 WoltLab GmbH
+ * @copyright  2001-2014 WoltLab GmbH
  * @license    GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @package    com.woltlab.wcf
  * @subpackage system.search
@@ -24,6 +25,12 @@ class SearchEngine extends SingletonFactory {
         */
        protected $availableObjectTypes = array();
        
+       /**
+        * MySQL's minimum word length for fulltext indices
+        * @var integer
+        */
+       protected static $ftMinWordLen = null;
+       
        /**
         * @see \wcf\system\SingletonFactory::init()
         */
@@ -189,6 +196,7 @@ class SearchEngine extends SingletonFactory {
                $previousChar = $tmp = '';
                $controlCharacterOrSpace = false;
                $chars = array('+', '-', '*');
+               $ftMinWordLen = self::getFulltextMinimumWordLength();
                for ($i = 0, $length = mb_strlen($query); $i < $length; $i++) {
                        $char = mb_substr($query, $i, 1);
                        
@@ -228,7 +236,23 @@ class SearchEngine extends SingletonFactory {
                         *   - is NOT +, - or *
                         */
                        if (($previousChar == '' || $previousChar == ' ') && !$inQuotes && !in_array($char, $chars)) {
-                               $tmp .= '+';
+                               // check if the term is shorter than MySQL's ft_min_word_len
+                               
+                               if ($i + $ftMinWordLen <= $length) {
+                                       $term = '';// $char;
+                                       for ($j = $i, $innerLength = $ftMinWordLen + $i; $j < $innerLength; $j++) {
+                                               $currentChar = mb_substr($query, $j, 1);
+                                               if ($currentChar == '"' || $currentChar == ' ' || in_array($currentChar, $chars)) {
+                                                       break;
+                                               }
+                                               
+                                               $term .= $currentChar;
+                                       }
+                                       
+                                       if (mb_strlen($term) == $ftMinWordLen) {
+                                               $tmp .= '+';
+                                       }
+                               }
                        }
                        
                        $tmp .= $char;
@@ -242,4 +266,29 @@ class SearchEngine extends SingletonFactory {
                
                return $tmp;
        }
+       
+       /**
+        * Returns MySQL's minimum word length for fulltext indices.
+        * 
+        * @return      integer
+        */
+       public static function getFulltextMinimumWordLength() {
+               if (self::$ftMinWordLen === null) {
+                       $sql = "SHOW VARIABLES LIKE ?";
+                       $statement = WCF::getDB()->prepareStatement($sql);
+                       
+                       try {
+                               $statement->execute(array('ft_min_word_len'));
+                               $row = $statement->fetchArray();
+                       }
+                       catch (DatabaseException $e) {
+                               // fallback if user is disallowed to issue 'SHOW VARIABLES'
+                               $row = array('Value' => 4);
+                       }
+                       
+                       self::$ftMinWordLen = $row['Value'];
+               }
+               
+               return self::$ftMinWordLen;
+       }
 }