From 3dc0205ffa348840e022fa73b3596bcd45eb2a3d Mon Sep 17 00:00:00 2001
From: yhirose <yuji.hirose.bug@gmail.com>
Date: Sun, 26 Jan 2020 23:00:37 -0500
Subject: [PATCH] Handle an invalid escape sequence char

---
 peglib.h     |  3 +++
 test/test.cc | 31 +++++++++++++++++++++++++++----
 2 files changed, 30 insertions(+), 4 deletions(-)

diff --git a/peglib.h b/peglib.h
index cd782a8..bc14c39 100644
--- a/peglib.h
+++ b/peglib.h
@@ -383,6 +383,9 @@ inline std::string resolve_escape_sequence(const char* s, size_t n) {
         auto ch = s[i];
         if (ch == '\\') {
             i++;
+            if (i == n) {
+                throw std::runtime_error("Invalid escape sequence...");
+            }
             switch (s[i]) {
                 case 'n':  r += '\n'; i++; break;
                 case 'r':  r += '\r'; i++; break;
diff --git a/test/test.cc b/test/test.cc
index 29dc243..d288c53 100644
--- a/test/test.cc
+++ b/test/test.cc
@@ -20,10 +20,10 @@ TEST_CASE("Simple syntax test (with unicode)", "[general]")
 
 TEST_CASE("Simple syntax test", "[general]")
 {
-    peg::parser parser(
-        " ROOT <- _ "
-        " _ <- ' ' "
-    );
+    peg::parser parser(R"(
+        ROOT <- _
+        _ <- ' '
+    )");
 
     bool ret = parser;
     REQUIRE(ret == true);
@@ -36,6 +36,28 @@ TEST_CASE("Empty syntax test", "[general]")
     REQUIRE(ret == false);
 }
 
+TEST_CASE("Backslash escape sequence test", "[general]")
+{
+    peg::parser parser(R"(
+        ROOT <- _
+        _ <- '\\'
+    )");
+
+    bool ret = parser;
+    REQUIRE(ret == true);
+}
+
+TEST_CASE("Invalid escape sequence test", "[general]")
+{
+    peg::parser parser(R"(
+        ROOT <- _
+        _ <- '\'
+    )");
+
+    bool ret = parser;
+    REQUIRE(ret == false);
+}
+
 TEST_CASE("Infinite loop 1", "[infinite loop]")
 {
     peg::parser pg(R"(
@@ -1727,6 +1749,7 @@ TEST_CASE("PEG Literal", "[peg]")
     REQUIRE(exact(g, "Literal", "\"'\"abc\"'\" ") == false);
     REQUIRE(exact(g, "Literal", "abc") == false);
     REQUIRE(exact(g, "Literal", "") == false);
+    REQUIRE(exact(g, "Literal", "\\") == false);
     REQUIRE(exact(g, "Literal", u8"'日本語'") == true);
     REQUIRE(exact(g, "Literal", u8"\"日本語\"") == true);
     REQUIRE(exact(g, "Literal", u8"日本語") == false);