From be96f4d7fb0cabced5bc6a9368977ddfe02d1f71 Mon Sep 17 00:00:00 2001
From: ylavic <ylavic.dev@gmail.com>
Date: Sun, 2 Dec 2018 23:26:58 +0100
Subject: [PATCH 1/2] GenericRegex: don't throw/abort on syntax error (unclosed
 parenthesis).

---
 include/rapidjson/internal/regex.h | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/include/rapidjson/internal/regex.h b/include/rapidjson/internal/regex.h
index 377f86c..16e3559 100644
--- a/include/rapidjson/internal/regex.h
+++ b/include/rapidjson/internal/regex.h
@@ -395,8 +395,7 @@ private:
                 }
                 return false;
 
-            default: 
-                RAPIDJSON_ASSERT(op == kOneOrMore);
+            case kOneOrMore:
                 if (operandStack.GetSize() >= sizeof(Frag)) {
                     Frag e = *operandStack.template Pop<Frag>(1);
                     SizeType s = NewState(kRegexInvalidState, e.start, 0);
@@ -405,6 +404,10 @@ private:
                     return true;
                 }
                 return false;
+
+            default: 
+                // syntax error (e.g. unclosed kLeftParenthesis)
+                return false;
         }
     }
 

From 8c147873980f4a9cc5e5cbf4248fccd5fdd8b57c Mon Sep 17 00:00:00 2001
From: ylavic <ylavic.dev@gmail.com>
Date: Mon, 3 Dec 2018 11:49:34 +0100
Subject: [PATCH 2/2] Unit test for invalid GenericRegex (unclosed
 parenthesis).

---
 test/unittest/regextest.cpp | 1 +
 1 file changed, 1 insertion(+)

diff --git a/test/unittest/regextest.cpp b/test/unittest/regextest.cpp
index cdd3630..cf89973 100644
--- a/test/unittest/regextest.cpp
+++ b/test/unittest/regextest.cpp
@@ -595,6 +595,7 @@ TEST(Regex, Invalid) {
     TEST_INVALID("");
     TEST_INVALID("a|");
     TEST_INVALID("()");
+    TEST_INVALID("(");
     TEST_INVALID(")");
     TEST_INVALID("(a))");
     TEST_INVALID("(a|)");