From e488de0d46ae563031f06d1b256ac811e6daa837 Mon Sep 17 00:00:00 2001
From: BlackMATov <blackmatov@gmail.com>
Date: Fri, 22 Nov 2019 03:10:30 +0700
Subject: [PATCH] add to_underlying traits function

---
 headers/enum.hpp/enum.hpp | 14 ++++++++++----
 untests/enum_tests.cpp    | 21 +++++++++++++++++++++
 2 files changed, 31 insertions(+), 4 deletions(-)

diff --git a/headers/enum.hpp/enum.hpp b/headers/enum.hpp/enum.hpp
index 5955176..e197e40 100644
--- a/headers/enum.hpp/enum.hpp
+++ b/headers/enum.hpp/enum.hpp
@@ -8,6 +8,7 @@
 
 #include <stdexcept>
 #include <string_view>
+#include <type_traits>
 
 namespace enum_hpp
 {
@@ -96,7 +97,7 @@ namespace enum_hpp::detail
     enum Enum : Type {\
         ENUM_HPP_GENERATE_ENUM_FIELDS(Fields)\
     };\
-    ENUM_HPP_TRAITS_IMPL(Enum, Type, Fields)
+    ENUM_HPP_TRAITS_DECL(Enum, Fields)
 
 //
 // ENUM_HPP_CLASS_DECL
@@ -106,21 +107,26 @@ namespace enum_hpp::detail
     enum class Enum : Type {\
         ENUM_HPP_GENERATE_ENUM_FIELDS(Fields)\
     };\
-    ENUM_HPP_TRAITS_IMPL(Enum, Type, Fields)
+    ENUM_HPP_TRAITS_DECL(Enum, Fields)
 
 //
-// ENUM_HPP_TRAITS_IMPL
+// ENUM_HPP_TRAITS_DECL
 //
 
-#define ENUM_HPP_TRAITS_IMPL(Enum, Type, Fields)\
+#define ENUM_HPP_TRAITS_DECL(Enum, Fields)\
     struct Enum##_traits {\
     private:\
         enum enum_names_for_this_score_ { ENUM_HPP_GENERATE_ENUM_FIELDS(Fields) };\
     public:\
+        using underlying_t = std::underlying_type_t<Enum>;\
         static constexpr std::size_t size = ENUM_HPP_PP_SEQ_SIZE(Fields);\
         static constexpr const Enum values[] = { ENUM_HPP_GENERATE_VALUES(Enum, Fields) };\
         static constexpr const std::string_view names[] = { ENUM_HPP_GENERATE_NAMES(Fields) };\
     public:\
+        static constexpr underlying_t to_underlying(Enum e) noexcept {\
+            return static_cast<underlying_t>(e);\
+        }\
+        \
         static constexpr std::string_view to_string(Enum e) noexcept {\
             for ( std::size_t i = 0; i < size; ++i) {\
                 if ( e == values[i] ) {\
diff --git a/untests/enum_tests.cpp b/untests/enum_tests.cpp
index 109f2f3..72365bf 100644
--- a/untests/enum_tests.cpp
+++ b/untests/enum_tests.cpp
@@ -107,6 +107,27 @@ TEST_CASE("enum") {
         }
     }
 
+    SECTION("to_underlying") {
+        {
+            STATIC_REQUIRE(sn::color_traits::to_underlying(sn::color::red) == enum_to_underlying(sn::color::red));
+            STATIC_REQUIRE(sn::color_traits::to_underlying(sn::color::green) == enum_to_underlying(sn::color::green));
+            STATIC_REQUIRE(sn::color_traits::to_underlying(sn::color::blue) == enum_to_underlying(sn::color::blue));
+            STATIC_REQUIRE(sn::color_traits::to_underlying(sn::color(42)) == 42);
+        }
+        {
+            STATIC_REQUIRE(sn::render::mask_traits::to_underlying(sn::render::mask::none) == enum_to_underlying(sn::render::mask::none));
+            STATIC_REQUIRE(sn::render::mask_traits::to_underlying(sn::render::mask::color) == enum_to_underlying(sn::render::mask::color));
+            STATIC_REQUIRE(sn::render::mask_traits::to_underlying(sn::render::mask::alpha) == enum_to_underlying(sn::render::mask::alpha));
+            STATIC_REQUIRE(sn::render::mask_traits::to_underlying(sn::render::mask::all) == enum_to_underlying(sn::render::mask::all));
+        }
+        {
+            STATIC_REQUIRE(sn::numbers_traits::to_underlying(sn::_0) == enum_to_underlying(sn::_0));
+            STATIC_REQUIRE(sn::numbers_traits::to_underlying(sn::_180) == enum_to_underlying(sn::_180));
+            STATIC_REQUIRE(sn::numbers_traits::to_underlying(sn::_240) == enum_to_underlying(sn::_240));
+            STATIC_REQUIRE(sn::numbers_traits::to_underlying(sn::numbers(100500)) == 100500);
+        }
+    }
+
     SECTION("to_string") {
         {
             STATIC_REQUIRE(sn::color_traits::to_string(sn::color::red) == "red");