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
@@ -13,6 +13,8 @@
   // faster; do not access them directly.
   public $children = array();
   public $parentNode;
+  public $previousSibling = null;
+  public $nextSibling = null;
 
   private $selectCache;
 
@@ -41,6 +43,14 @@
     return $this->parentNode;
   }
 
+  final public function getPreviousSibling() {
+    return $this->previousSibling;
+  }
+
+  final public function getNextSibling() {
+    return $this->nextSibling;
+  }
+
   final public function getID() {
     return $this->id;
   }
diff --git a/src/parser/aast/api/AASTTree.php b/src/parser/aast/api/AASTTree.php
--- a/src/parser/aast/api/AASTTree.php
+++ b/src/parser/aast/api/AASTTree.php
@@ -141,9 +141,23 @@
     foreach ($nodes as $node_id => $node) {
       if (isset($node[3])) {
         $children = $this->buildTree($node[3]);
-        foreach ($children as $child) {
+        $previous_child = null;
+
+        foreach ($children as $ii => $child) {
           $child->parentNode = $this->tree[$node_id];
+          $child->previousSibling = $previous_child;
+
+          if ($previous_child) {
+            $previous_child->nextSibling = $child;
+          }
+
+          $previous_child = $child;
         }
+
+        if ($previous_child) {
+          $previous_child->nextSibling = $child;
+        }
+
         $this->tree[$node_id]->children = $children;
       }
     }