diff --git a/src/parser/aast/api/AASTNode.php b/src/parser/aast/api/AASTNode.php
--- a/src/parser/aast/api/AASTNode.php
+++ b/src/parser/aast/api/AASTNode.php
@@ -180,6 +180,18 @@
     return $tokens;
   }
 
+  final public function isDescendant(AASTNode $node) {
+    while ($node) {
+      if ($this === $node) {
+        return true;
+      }
+
+      $node = $node->getParentNode();
+    }
+
+    return false;
+  }
+
   public function selectDescendantsOfType($type_name) {
     return $this->selectDescendantsOfTypes(array($type_name));
   }