From 5337d8da14872ff694cc2732d83e9a27ed7236e8 Mon Sep 17 00:00:00 2001
From: Jeanine Adkisson <jeanine.adkisson@gmail.com>
Date: Tue, 13 Oct 2020 14:20:52 -0400
Subject: [PATCH] Improve optional chaining in JavaScript lexer (#1594)

Previously, the example `${obj?.prop}` would result in a runaway string
literal, since the `?` would start a ternary expression, and Rouge
would lose the stack state causing the second `` ` `` to terminate the
literal. This commit fixes that issue.
---
 lib/rouge/lexers/javascript.rb | 4 ++++
 spec/visual/samples/javascript | 2 ++
 2 files changed, 6 insertions(+)

diff --git a/lib/rouge/lexers/javascript.rb b/lib/rouge/lexers/javascript.rb
index bc45af6c28..9ac323aba9 100644
--- a/lib/rouge/lexers/javascript.rb
+++ b/lib/rouge/lexers/javascript.rb
@@ -162,6 +162,10 @@ def self.id_regex
           push :template_string
         end
 
+        # special case for the safe navigation operator ?.
+        # so that we don't start detecting a ternary expr
+        rule %r/[?][.]/, Punctuation
+
         rule %r/[?]/ do
           token Punctuation
           push :ternary
diff --git a/spec/visual/samples/javascript b/spec/visual/samples/javascript
index ccdb5e3776..e6396ed0b3 100644
--- a/spec/visual/samples/javascript
+++ b/spec/visual/samples/javascript
@@ -229,6 +229,8 @@ function* range(from, to)
   1 + 2
 }`;
 
+var notATernary = `${obj?.prop}`;
+
 @(function(thing) { return thing; })
 class Person {
   @deprecate