From 1c9f9c8f9f6d1da380384e91f5b8559bba4ce02e Mon Sep 17 00:00:00 2001
From: q66 <daniel@octaforge.org>
Date: Thu, 22 Sep 2016 01:15:51 +0200
Subject: [PATCH] safe lexing with unterminated strings

---
 src/cs_vm.hh | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/src/cs_vm.hh b/src/cs_vm.hh
index 8b3cafa..8930457 100644
--- a/src/cs_vm.hh
+++ b/src/cs_vm.hh
@@ -218,7 +218,10 @@ struct GenState {
         return *source++;
     }
 
-    char current(int ahead = 0) {
+    char current(ostd::Size ahead = 0) {
+        if (source.size() <= ahead) {
+            return '\0';
+        }
         return source[ahead];
     }