switched to namespace first, PSR-0 as a fallback

src/Node/Expression/AbstractExpression.php

@@ -1,11 +1,26 @@
 <?php
 
+/*
+ * This file is part of Twig.
+ *
+ * (c) Fabien Potencier
+ * (c) Armin Ronacher
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
 namespace Twig\Node\Expression;
 
-class_exists('Twig_Node_Expression');
+use Twig\Node\Node;
 
-if (\false) {
-    class AbstractExpression extends \Twig_Node_Expression
-    {
-    }
+/**
+ * Abstract class for all nodes that represents an expression.
+ *
+ * @author Fabien Potencier <fabien@symfony.com>
+ */
+abstract class AbstractExpression extends Node
+{
 }
+
+class_alias('Twig\Node\Expression\AbstractExpression', 'Twig_Node_Expression');