From dde351ea40368b0a06e60421bc5e3d1cbf8ec3ee Mon Sep 17 00:00:00 2001
From: ToruNiina <niina.toru.68u@gmail.com>
Date: Wed, 16 Mar 2022 22:39:52 +0900
Subject: [PATCH] feat: add escape sequence of ESC

as an unreleased feature
---
 tests/test_parse_string.cpp | 13 +++++++++++++
 toml/lexer.hpp              |  3 +++
 toml/parser.hpp             |  3 +++
 3 files changed, 19 insertions(+)

diff --git a/tests/test_parse_string.cpp b/tests/test_parse_string.cpp
index df4b787..5367c00 100644
--- a/tests/test_parse_string.cpp
+++ b/tests/test_parse_string.cpp
@@ -217,6 +217,19 @@ BOOST_AUTO_TEST_CASE(test_ml_literal_string_value)
         value("'This,' she said, 'is just a pointless statement.'", string_t::literal));
 }
 
+BOOST_AUTO_TEST_CASE(test_simple_excape_sequences)
+{
+    TOML11_TEST_PARSE_EQUAL(parse_string,
+            R"("\"\\\b\f\n\r\t")",
+            string("\"\\\b\f\n\r\t", string_t::basic));
+#ifdef TOML11_USE_UNRELEASED_TOML_FEATURES
+    TOML11_TEST_PARSE_EQUAL(parse_string,
+            R"("\e")",
+            string("\x1b", string_t::basic));
+#endif
+}
+
+
 BOOST_AUTO_TEST_CASE(test_unicode_escape_sequence)
 {
 #if defined(_MSC_VER) || defined(__INTEL_COMPILER)
diff --git a/toml/lexer.hpp b/toml/lexer.hpp
index ea5050b..5d019a3 100644
--- a/toml/lexer.hpp
+++ b/toml/lexer.hpp
@@ -133,6 +133,9 @@ using lex_escape_seq_char = either<character<'"'>, character<'\\'>,
                                    character<'b'>, character<'f'>,
                                    character<'n'>, character<'r'>,
                                    character<'t'>,
+#ifdef TOML11_USE_UNRELEASED_TOML_FEATURES
+                                   character<'e'>, // ESC (0x1B)
+#endif
                                    lex_escape_unicode_short,
                                    lex_escape_unicode_long
                                    >;
diff --git a/toml/parser.hpp b/toml/parser.hpp
index bfa5531..e51708e 100644
--- a/toml/parser.hpp
+++ b/toml/parser.hpp
@@ -327,6 +327,9 @@ inline result<std::string, std::string> parse_escape_sequence(location& loc)
         case 'n' :{loc.advance(); return ok(std::string("\n"));}
         case 'f' :{loc.advance(); return ok(std::string("\f"));}
         case 'r' :{loc.advance(); return ok(std::string("\r"));}
+#ifdef TOML11_USE_UNRELEASED_TOML_FEATURES
+        case 'e' :{loc.advance(); return ok(std::string("\x1b"));} // ESC
+#endif
         case 'u' :
         {
             if(const auto token = lex_escape_unicode_short::invoke(loc))