Fix broken search results highlighting

Author: flodolo

app/classes/Transvision/Utils.php

@@ -119,8 +119,21 @@ public static function markString($needle, $haystack)
      */
     public static function highlightString($str)
     {
+        /*
+            [^←→]: matches any character but the marker characters.
+            [^←→]|(?R): matches any character but the marker characters,
+                        or recursively the entire pattern.
+
+            This is wrapped in a non capturing group (?:), since we're
+            only interested in the content of the more external markers.
+            For example, for “←←A→dd→” we're only interested in “←A→dd”,
+            capturing “←A→” is not useful.
+            Internal extra markers are later removed by str_replace.
+
+            See also http://stackoverflow.com/a/14952740
+        */
         $str = preg_replace(
-            '/←(.*)→/isU',
+            '/←((?:[^←→]|(?R))*)→/iu',
             "<span class='highlight'>$1</span>",
             $str
         );

tests/units/Transvision/Utils.php

@@ -176,6 +176,7 @@ public function highlightStringDP()
             ['←Cronologia→ di navigazione', '<span class=\'highlight\'>Cronologia</span> di navigazione'],
             ['←servi←ce→→', '<span class=\'highlight\'>service</span>'],
             ['Cronologia di navigazione', 'Cronologia di navigazione'],
+            ['←←A→dd→ more ←se←a→rch→ ←engine→s…', '<span class=\'highlight\'>Add</span> more <span class=\'highlight\'>search</span> <span class=\'highlight\'>engine</span>s…'],
         ];
     }