diff --git a/src/parser/aast/api/AASTNode.php b/src/parser/aast/api/AASTNode.php
index 9cf1408..7411de2 100644
--- a/src/parser/aast/api/AASTNode.php
+++ b/src/parser/aast/api/AASTNode.php
@@ -1,339 +1,349 @@
 <?php
 
 abstract class AASTNode extends Phobject {
 
   protected $id;
   protected $l;
   protected $r;
   protected $typeID;
   protected $typeName;
   protected $tree;
 
   // These are public only as a microoptimization to make tree construction
   // faster; do not access them directly.
   public $children = array();
   public $parentNode;
+  public $previousSibling = null;
+  public $nextSibling = null;
 
   private $selectCache;
 
   abstract public function isStaticScalar();
   abstract public function getDocblockToken();
   abstract public function evalStatic();
   abstract public function getStringLiteralValue();
 
   public function __construct($id, array $data, AASTTree $tree) {
     $this->id = $id;
     $this->typeID = $data[0];
     if (isset($data[1])) {
       $this->l = $data[1];
     } else {
       $this->l = -1;
     }
     if (isset($data[2])) {
       $this->r = $data[2];
     } else {
       $this->r = -1;
     }
     $this->tree = $tree;
   }
 
   final public function getParentNode() {
     return $this->parentNode;
   }
 
+  final public function getPreviousSibling() {
+    return $this->previousSibling;
+  }
+
+  final public function getNextSibling() {
+    return $this->nextSibling;
+  }
+
   final public function getID() {
     return $this->id;
   }
 
   final public function getTypeID() {
     return $this->typeID;
   }
 
   final public function getTree() {
     return $this->tree;
   }
 
   final public function getTypeName() {
     if (empty($this->typeName)) {
       $this->typeName =
         $this->tree->getNodeTypeNameFromTypeID($this->getTypeID());
     }
     return $this->typeName;
   }
 
   final public function getChildren() {
     return $this->children;
   }
 
   public function getChildrenOfType($type) {
     $nodes = array();
 
     foreach ($this->children as $child) {
       if ($child->getTypeName() == $type) {
         $nodes[] = $child;
       }
     }
 
     return $nodes;
   }
 
   public function getChildOfType($index, $type) {
     $child = $this->getChildByIndex($index);
     if ($child->getTypeName() != $type) {
       throw new Exception(
         pht(
           "Child in position '%d' is not of type '%s': %s",
           $index,
           $type,
           $this->getDescription()));
     }
 
     return $child;
   }
 
   public function getChildByIndex($index) {
     // NOTE: Microoptimization to avoid calls like array_values() or idx().
 
     $idx = 0;
     foreach ($this->children as $child) {
       if ($idx == $index) {
         return $child;
       }
       ++$idx;
     }
 
     throw new Exception(pht("No child with index '%d'.", $index));
   }
 
   /**
    * Build a cache to improve the performance of
    * @{method:selectDescendantsOfType}. This cache makes a time/memory tradeoff
    * by aggressively caching node descendants. It may improve the tree's query
    * performance substantially if you make a large number of queries, but also
    * requires a significant amount of memory.
    *
    * This builds a cache for the entire tree and improves performance of all
    * @{method:selectDescendantsOfType} calls.
    */
   public function buildSelectCache() {
     $cache = array();
     foreach ($this->getChildren() as $id => $child) {
       $type_id = $child->getTypeID();
       if (empty($cache[$type_id])) {
         $cache[$type_id] = array();
       }
       $cache[$type_id][$id] = $child;
       foreach ($child->buildSelectCache() as $type_id => $nodes) {
         if (empty($cache[$type_id])) {
           $cache[$type_id] = array();
         }
         $cache[$type_id] += $nodes;
       }
     }
     $this->selectCache = $cache;
     return $this->selectCache;
   }
 
   /**
    * Build a cache to improve the performance of @{method:selectTokensOfType}.
    * This cache makes a time/memory tradeoff by aggressively caching token
    * types. It may improve the tree's query performance substantially if you
    * make a large number of queries, but also requires a significant amount of
    * memory.
    *
    * This builds a cache for this node only.
    */
   public function buildTokenCache() {
     $cache = array();
     foreach ($this->getTokens() as $id => $token) {
       $cache[$token->getTypeName()][$id] = $token;
     }
     $this->tokenCache = $cache;
     return $this->tokenCache;
   }
 
   public function selectTokensOfType($type_name) {
     return $this->selectTokensOfTypes(array($type_name));
   }
 
   /**
    * Select all tokens of any given types.
    */
   public function selectTokensOfTypes(array $type_names) {
     $tokens = array();
 
     foreach ($type_names as $type_name) {
       if (isset($this->tokenCache)) {
         $cached_tokens = idx($this->tokenCache, $type_name, array());
         foreach ($cached_tokens as $id => $cached_token) {
           $tokens[$id] = $cached_token;
         }
       } else {
         foreach ($this->getTokens() as $id => $token) {
           if ($token->getTypeName() == $type_name) {
             $tokens[$id] = $token;
           }
         }
       }
     }
 
     return $tokens;
   }
 
   final public function isDescendantOf(AASTNode $node) {
     for ($it = $this; $it !== null; $it = $it->getParentNode()) {
       if ($it === $node) {
         return true;
       }
     }
 
     return false;
   }
 
   public function selectDescendantsOfType($type_name) {
     return $this->selectDescendantsOfTypes(array($type_name));
   }
 
   public function selectDescendantsOfTypes(array $type_names) {
     $nodes = array();
     foreach ($type_names as $type_name) {
       $type = $this->getTypeIDFromTypeName($type_name);
 
       if (isset($this->selectCache)) {
         if (isset($this->selectCache[$type])) {
           $nodes = $nodes + $this->selectCache[$type];
         }
       } else {
         $nodes = $nodes + $this->executeSelectDescendantsOfType($this, $type);
       }
     }
 
     return AASTNodeList::newFromTreeAndNodes($this->tree, $nodes);
   }
 
   protected function executeSelectDescendantsOfType($node, $type) {
     $results = array();
     foreach ($node->getChildren() as $id => $child) {
       if ($child->getTypeID() == $type) {
         $results[$id] = $child;
       }
       $results += $this->executeSelectDescendantsOfType($child, $type);
     }
     return $results;
   }
 
   public function getTokens() {
     if ($this->l == -1 || $this->r == -1) {
       return array();
     }
     $tokens = $this->tree->getRawTokenStream();
     $result = array();
     foreach (range($this->l, $this->r) as $token_id) {
       $result[$token_id] = $tokens[$token_id];
     }
     return $result;
   }
 
   public function getConcreteString() {
     $values = array();
     foreach ($this->getTokens() as $token) {
       $values[] = $token->getValue();
     }
     return implode('', $values);
   }
 
   public function getSemanticString() {
     $tokens = $this->getTokens();
     foreach ($tokens as $id => $token) {
       if ($token->isComment()) {
         unset($tokens[$id]);
       }
     }
     return implode('', mpull($tokens, 'getValue'));
   }
 
   public function getIndentation() {
     $tokens = $this->getTokens();
     $left = head($tokens);
 
     while ($left &&
            (!$left->isAnyWhitespace() ||
             strpos($left->getValue(), "\n") === false)) {
       $left = $left->getPrevToken();
     }
 
     if (!$left) {
       return null;
     }
 
     return preg_replace("/^.*\n/s", '', $left->getValue());
   }
 
   public function getDescription() {
     $concrete = $this->getConcreteString();
     if (strlen($concrete) > 75) {
       $concrete = substr($concrete, 0, 36).'...'.substr($concrete, -36);
     }
 
     $concrete = addcslashes($concrete, "\\\n\"");
 
     return pht('a node of type %s: "%s"', $this->getTypeName(), $concrete);
   }
 
   final protected function getTypeIDFromTypeName($type_name) {
     return $this->tree->getNodeTypeIDFromTypeName($type_name);
   }
 
   final public function getOffset() {
     $stream = $this->tree->getRawTokenStream();
     if (empty($stream[$this->l])) {
       return null;
     }
     return $stream[$this->l]->getOffset();
   }
 
   final public function getLength() {
     $stream = $this->tree->getRawTokenStream();
     if (empty($stream[$this->r])) {
       return null;
     }
     return $stream[$this->r]->getOffset() - $this->getOffset();
   }
 
 
   public function getSurroundingNonsemanticTokens() {
     $before = array();
     $after  = array();
 
     $tokens = $this->tree->getRawTokenStream();
 
     if ($this->l != -1) {
       $before = $tokens[$this->l]->getNonsemanticTokensBefore();
     }
 
     if ($this->r != -1) {
       $after = $tokens[$this->r]->getNonsemanticTokensAfter();
     }
 
     return array($before, $after);
   }
 
   final public function getLineNumber() {
     return idx($this->tree->getOffsetToLineNumberMap(), $this->getOffset());
   }
 
   final public function getEndLineNumber() {
     return idx(
       $this->tree->getOffsetToLineNumberMap(),
       $this->getOffset() + $this->getLength());
   }
 
   public function dispose() {
     foreach ($this->getChildren() as $child) {
       $child->dispose();
     }
 
     unset($this->selectCache);
   }
 
 }
diff --git a/src/parser/aast/api/AASTTree.php b/src/parser/aast/api/AASTTree.php
index 6720e74..3c46e2f 100644
--- a/src/parser/aast/api/AASTTree.php
+++ b/src/parser/aast/api/AASTTree.php
@@ -1,180 +1,194 @@
 <?php
 
 /**
  * An abstract abstract syntax tree.
  */
 abstract class AASTTree extends Phobject {
 
   protected $tree = array();
   protected $stream = array();
   protected $lineMap;
   protected $rawSource;
 
   private $treeType = 'Abstract';
   private $tokenConstants;
   private $tokenReverseMap;
   private $nodeConstants;
   private $nodeReverseMap;
 
   abstract public function newNode($id, array $data, AASTTree $tree);
   abstract public function newToken(
     $id,
     $type,
     $value,
     $offset,
     AASTTree $tree);
 
   public function __construct(array $tree, array $stream, $source) {
     $ii = 0;
     $offset = 0;
 
     foreach ($stream as $token) {
       $this->stream[$ii] = $this->newToken(
         $ii,
         $token[0],
         substr($source, $offset, $token[1]),
         $offset,
         $this);
       $offset += $token[1];
       ++$ii;
     }
 
     $this->rawSource = $source;
     $this->buildTree(array($tree));
   }
 
   final public function setTreeType($description) {
     $this->treeType = $description;
     return $this;
   }
 
   final public function getTreeType() {
     return $this->treeType;
   }
 
   final public function setTokenConstants(array $token_map) {
     $this->tokenConstants = $token_map;
     $this->tokenReverseMap = array_flip($token_map);
     return $this;
   }
 
   final public function setNodeConstants(array $node_map) {
     $this->nodeConstants = $node_map;
     $this->nodeReverseMap = array_flip($node_map);
     return $this;
   }
 
   final public function getNodeTypeNameFromTypeID($type_id) {
     if (empty($this->nodeConstants[$type_id])) {
       $tree_type = $this->getTreeType();
       throw new Exception(
         pht(
           "No type name for node type ID '%s' in '%s' AAST.",
           $type_id,
           $tree_type));
     }
 
     return $this->nodeConstants[$type_id];
   }
 
   final public function getNodeTypeIDFromTypeName($type_name) {
     if (empty($this->nodeReverseMap[$type_name])) {
       $tree_type = $this->getTreeType();
       throw new Exception(
         pht(
           "No type ID for node type name '%s' in '%s' AAST.",
           $type_name,
           $tree_type));
     }
     return $this->nodeReverseMap[$type_name];
   }
 
   final public function getTokenTypeNameFromTypeID($type_id) {
     if (empty($this->tokenConstants[$type_id])) {
       $tree_type = $this->getTreeType();
       throw new Exception(
         pht(
           "No type name for token type ID '%s' in '%s' AAST.",
           $type_id,
           $tree_type));
     }
     return $this->tokenConstants[$type_id];
   }
 
   final public function getTokenTypeIDFromTypeName($type_name) {
     if (empty($this->tokenReverseMap[$type_name])) {
       $tree_type = $this->getTreeType();
       throw new Exception(
         pht(
           "No type ID for token type name '%s' in '%s' AAST.",
           $type_name,
           $tree_type));
     }
     return $this->tokenReverseMap[$type_name];
   }
 
   /**
    * Unlink internal datastructures so that PHP will garbage collect the tree.
    *
    * This renders the object useless.
    *
    * @return void
    */
   public function dispose() {
     $this->getRootNode()->dispose();
     unset($this->tree);
     unset($this->stream);
   }
 
   final public function getRootNode() {
     return $this->tree[0];
   }
 
   protected function buildTree(array $tree) {
     $ii = count($this->tree);
     $nodes = array();
     foreach ($tree as $node) {
       $this->tree[$ii] = $this->newNode($ii, $node, $this);
       $nodes[$ii] = $node;
       ++$ii;
     }
     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;
       }
     }
 
     $result = array();
     foreach ($nodes as $key => $node) {
       $result[$key] = $this->tree[$key];
     }
 
     return $result;
   }
 
   final public function getRawTokenStream() {
     return $this->stream;
   }
 
   public function getOffsetToLineNumberMap() {
     if ($this->lineMap === null) {
       $src = $this->rawSource;
       $len = strlen($src);
       $lno = 1;
       $map = array();
       for ($ii = 0; $ii < $len; ++$ii) {
         $map[$ii] = $lno;
         if ($src[$ii] == "\n") {
           ++$lno;
         }
       }
       $this->lineMap = $map;
     }
     return $this->lineMap;
   }
 
 }