From 23261c4f6f35c8790d1eda46b0ea98a1fca110a2 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Tu=E1=BA=A5n-Anh=20Nguy=E1=BB=85n?= <ubolonton@gmail.com>
Date: Thu, 27 Feb 2020 22:24:00 +0700
Subject: [PATCH] Make ts_language_symbol_name return NULL for out-of-bound ids

---
 lib/binding_rust/lib.rs | 11 +++++++----
 lib/src/language.c      |  4 +++-
 2 files changed, 10 insertions(+), 5 deletions(-)

diff --git a/lib/binding_rust/lib.rs b/lib/binding_rust/lib.rs
index 9da94510..a3f77dff 100644
--- a/lib/binding_rust/lib.rs
+++ b/lib/binding_rust/lib.rs
@@ -176,10 +176,13 @@ impl Language {
     }
 
     /// Get the name of the node kind for the given numerical id.
-    pub fn node_kind_for_id(&self, id: u16) -> &'static str {
-        unsafe { CStr::from_ptr(ffi::ts_language_symbol_name(self.0, id)) }
-            .to_str()
-            .unwrap()
+    pub fn node_kind_for_id(&self, id: u16) -> Option<&'static str> {
+        let ptr = unsafe { ffi::ts_language_symbol_name(self.0, id) };
+        if ptr.is_null() {
+            None
+        } else {
+            Some(unsafe { CStr::from_ptr(ptr) }.to_str().unwrap())
+        }
     }
 
     /// Get the numeric id for the given node kind.
diff --git a/lib/src/language.c b/lib/src/language.c
index 05b189c6..a396b4b0 100644
--- a/lib/src/language.c
+++ b/lib/src/language.c
@@ -72,8 +72,10 @@ const char *ts_language_symbol_name(
     return "ERROR";
   } else if (symbol == ts_builtin_sym_error_repeat) {
     return "_ERROR";
-  } else {
+  } else if (symbol < ts_language_symbol_count(self)) {
     return self->symbol_names[symbol];
+  } else {
+    return NULL;
   }
 }