1 files changed, 7 insertions, 7 deletions
diff --git a/src/Components/GroupKeyword.php b/src/Components/GroupKeyword.php
index c782288..bef1ebe 100644
--- a/src/Components/GroupKeyword.php
+++ b/src/Components/GroupKeyword.php
@@ -1,8 +1,8 @@
 <?php
-
 /**
  * `GROUP BY` keyword parser.
  */
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Components;
 
@@ -44,11 +44,11 @@ class GroupKeyword extends Component
      *
      * @return GroupKeyword[]
      */
-    public static function parse(Parser $parser, TokensList $list, array $options = array())
+    public static function parse(Parser $parser, TokensList $list, array $options = [])
     {
-        $ret = array();
+        $ret = [];
 
-        $expr = new self();
+        $expr = new static();
 
         /**
          * The state of the parser.
@@ -96,7 +96,7 @@ class GroupKeyword extends Component
                     if (! empty($expr->expr)) {
                         $ret[] = $expr;
                     }
-                    $expr = new self();
+                    $expr = new static();
                     $state = 0;
                 } else {
                     break;
@@ -120,12 +120,12 @@ class GroupKeyword extends Component
      *
      * @return string
      */
-    public static function build($component, array $options = array())
+    public static function build($component, array $options = [])
     {
         if (is_array($component)) {
             return implode(', ', $component);
         }
 
-        return trim($component->expr);
+        return trim((string) $component->expr);
     }
 }