From 1535ebd21caf616566f2f03989086f4fc93c0a3b Mon Sep 17 00:00:00 2001
From: Max Brunsfeld <maxbrunsfeld@gmail.com>
Date: Mon, 25 Aug 2014 11:28:09 -0700
Subject: [PATCH] Handle null parent in {next,prev}_sibling

---
 spec/runtime/node_spec.cc |  9 +++++++++
 src/runtime/node.c        | 10 ++++++++--
 2 files changed, 17 insertions(+), 2 deletions(-)

diff --git a/spec/runtime/node_spec.cc b/spec/runtime/node_spec.cc
index 24f389a6..f003caa0 100644
--- a/spec/runtime/node_spec.cc
+++ b/spec/runtime/node_spec.cc
@@ -73,6 +73,10 @@ describe("Node", []() {
       ts_node_release(array);
       ts_node_release(number);
     });
+
+    it("returns null if the node has no parent", [&]() {
+      AssertThat(ts_node_parent(root), Equals<TSNode *>(nullptr));
+    });
   });
 
   describe("next_sibling and prev_sibling", [&]() {
@@ -90,6 +94,11 @@ describe("Node", []() {
       ts_node_release(number2);
       ts_node_release(number3);
     });
+
+    it("returns null when the node has no parent", [&]() {
+      AssertThat(ts_node_next_sibling(root), Equals<TSNode *>(nullptr));
+      AssertThat(ts_node_prev_sibling(root), Equals<TSNode *>(nullptr));
+    });
   });
 
   describe("find_for_range", [&]() {
diff --git a/src/runtime/node.c b/src/runtime/node.c
index b6b94117..c42de7d6 100644
--- a/src/runtime/node.c
+++ b/src/runtime/node.c
@@ -53,11 +53,17 @@ const char *ts_node_string(const TSNode *node) {
 TSNode *ts_node_parent(TSNode *child) { return child->parent; }
 
 TSNode *ts_node_prev_sibling(TSNode *child) {
-  return ts_node_child(child->parent, child->index - 1);
+  if (child->parent)
+    return ts_node_child(child->parent, child->index - 1);
+  else
+    return NULL;
 }
 
 TSNode *ts_node_next_sibling(TSNode *child) {
-  return ts_node_child(child->parent, child->index + 1);
+  if (child->parent)
+    return ts_node_child(child->parent, child->index + 1);
+  else
+    return NULL;
 }
 
 size_t ts_node_child_count(const TSNode *parent) {