From 498cddf99ffa07c9c847e544309fa147c0c3654f Mon Sep 17 00:00:00 2001
From: terik23 <neargye@gmail.com>
Date: Mon, 8 Apr 2019 22:55:35 +0500
Subject: [PATCH] update nameof_enum

---
 README.md           | 52 +++++++++++++++++++++++-
 example/example.cpp |  5 ---
 include/nameof.hpp  | 99 +++++++++++++++++----------------------------
 test/test.cpp       | 63 ++++-------------------------
 4 files changed, 94 insertions(+), 125 deletions(-)

diff --git a/README.md b/README.md
index 7b234a7..7885077 100644
--- a/README.md
+++ b/README.md
@@ -86,10 +86,19 @@ Header-only C++17 library provides nameof macros and functions to obtain simple
 
 * Nameof expression argument are identified, but do not evaluated.
 
-* Enum variable must be in range `(-NAMEOF_ENUM_RANGE, NAMEOF_ENUM_RANGE)`. By default `NAMEOF_ENUM_RANGE = 128`. If you need a larger range, redefine the macro `NAMEOF_ENUM_RANGE`.
+* Enum value must be in range `[-256, 256]`. If you need another range, add specialization enum_range for necessary enum type.
   ```cpp
-  #define NAMEOF_ENUM_RANGE 1028 // Redefine NAMEOF_ENUM_RANGE for larger range.
   #include <nameof.hpp>
+
+  enum number { one = 100, two = 200, three = 300 };
+
+  namespace nameof {
+  template <>
+  struct enum_range<number> {
+    static constexpr int min = 100;
+    static constexpr int max = 300;
+  };
+  }
   ```
 
 * If you need name with template suffix, use NAMEOF_FULL.
@@ -113,6 +122,45 @@ Header-only C++17 library provides nameof macros and functions to obtain simple
   NAMEOF(	somevar	) -> "somevar"
   ```
 
+* Nameof enum obtains the first defined value enums, and won't work if value are aliased.
+  ```cpp
+  enum ShapeKind {
+    ConvexBegin = 0,
+    Box = 0, // Won't work.
+    Sphere = 1,
+    ConvexEnd = 2,
+    Donut = 2, // Won't work too.
+    Banana = 3,
+    COUNT = 4,
+  };
+  // NAMEOF_ENUM(ShapeKind::Box) -> "ConvexBegin"
+  // nameof::nameof_enum(ShapeKind::Box) -> "ConvexBegin"
+  ```
+  Work around the issue:
+  ```cpp
+  enum ShapeKind {
+    // Convex shapes, see ConvexBegin and ConvexEnd below.
+    Box = 0,
+    Sphere = 1,
+
+    // Non-convex shapes.
+    Donut = 2,
+    Banana = 3,
+
+    COUNT = Banana + 1,
+
+    // Non-reflected aliases.
+    ConvexBegin = Box,
+    ConvexEnd = Sphere + 1,
+  };
+  // NAMEOF_ENUM(ShapeKind::Box) -> "Box"
+  // nameof::nameof_enum(ShapeKind::Box) -> "Box"
+
+  // Non-reflected aliases.
+  // NAMEOF_ENUM(ShapeKind::ConvexBegin) -> "Box"
+  // nameof::nameof_enum(ShapeKind::ConvexBegin) -> "Box"
+  ```
+
 ## Integration
 
 You should add required file [nameof.hpp](include/nameof.hpp).
diff --git a/example/example.cpp b/example/example.cpp
index 399e2ac..0a3154e 100644
--- a/example/example.cpp
+++ b/example/example.cpp
@@ -93,11 +93,6 @@ int main() {
   std::cout << nameof::nameof_enum(color) << std::endl; // 'RED'
   std::cout << NAMEOF_ENUM(color) << std::endl; // 'RED'
 
-  // Nameof static storage enum variable.
-  constexpr auto const_color = Color::BLUE;
-  std::cout << nameof::nameof_enum<const_color>() << std::endl; // 'BLUE'
-  std::cout << NAMEOF_CONST_ENUM(const_color) << std::endl; // 'BLUE'
-
   // Nameof.
   std::cout << NAMEOF(structvar) << std::endl; // 'structvar'
   std::cout << NAMEOF(::structvar) << std::endl; // 'structvar'
diff --git a/include/nameof.hpp b/include/nameof.hpp
index 80bb121..abafc76 100644
--- a/include/nameof.hpp
+++ b/include/nameof.hpp
@@ -31,24 +31,21 @@
 
 #pragma once
 
+#include <array>
 #include <cstddef>
-#include <type_traits>
 #include <limits>
+#include <type_traits>
 #include <string_view>
 
-// Enum variable must be in range (-NAMEOF_ENUM_RANGE, NAMEOF_ENUM_RANGE). If you need a larger range, redefine the macro NAMEOF_ENUM_RANGE.
-#if !defined(NAMEOF_ENUM_RANGE)
-#  define NAMEOF_ENUM_RANGE 128
-#endif
-
 namespace nameof {
 
-static_assert(NAMEOF_ENUM_RANGE > 0,
-              "NAMEOF_ENUM_RANGE must be positive and greater than zero.");
-static_assert(NAMEOF_ENUM_RANGE % 8 == 0,
-              "NAMEOF_ENUM_RANGE must be a multiple of 8.");
-static_assert(NAMEOF_ENUM_RANGE < std::numeric_limits<int>::max(),
-              "NAMEOF_ENUM_RANGE must be less INT_MAX.");
+// Enum value must be in range [-256, 256]. If you need another range, add specialization enum_range for necessary enum type.
+template <typename E>
+struct enum_range final {
+  static_assert(std::is_enum_v<E>, "nameof::enum_range requires enum type.");
+  static constexpr int min = std::is_signed_v<std::underlying_type_t<E>> ? -256 : 0;
+  static constexpr int max = 256;
+};
 
 namespace detail {
 
@@ -168,13 +165,14 @@ template <typename T>
   while (name.back() == ' ') {
     name.remove_suffix(1);
   }
+
   return name;
 #endif
 }
 
 template <typename E, E V>
-[[nodiscard]] constexpr std::string_view nameof_enum_impl() noexcept {
-  static_assert(std::is_enum_v<E>, "nameof::nameof_enum require enum type.");
+[[nodiscard]] constexpr std::string_view enum_name_impl() noexcept {
+  static_assert(std::is_enum_v<E>, "nameof::enum_name_impl requires enum type.");
 #if defined(__clang__)
   std::string_view name{__PRETTY_FUNCTION__};
   constexpr auto suffix = sizeof("]") - 1;
@@ -190,48 +188,37 @@ template <typename E, E V>
 
 #if defined(__clang__) || (defined(__GNUC__) && __GNUC__ >= 9) || defined(_MSC_VER)
   name.remove_suffix(suffix);
+
   return pretty_name(name, false);
 #endif
 }
 
-template <typename E, int V>
-struct nameof_enum_impl_t final {
-  [[nodiscard]] constexpr std::string_view operator()(int value) const noexcept {
-    static_assert(std::is_enum_v<E>, "nameof::nameof_enum require enum type.");
-    if constexpr (V > std::numeric_limits<std::underlying_type_t<E>>::max()) {
-      return {}; // Enum variable out of range.
-    }
+template <typename E, int... I>
+[[nodiscard]] constexpr decltype(auto) enum_strings_impl(std::integer_sequence<int, I...>) noexcept {
+  static_assert(std::is_enum_v<E>, "magic_enum::detail::enum_strings_impl requires enum type.");
+  using U = std::underlying_type_t<E>;
+  constexpr int min = (enum_range<E>::min > std::numeric_limits<U>::min()) ? enum_range<E>::min : std::numeric_limits<U>::min();
+  constexpr std::array<std::string_view, sizeof...(I)> enum_names{{enum_name_impl<E, static_cast<E>(I + min)>()...}};
 
-    switch (value - V) {
-      case 0:
-        return nameof_enum_impl<E, static_cast<E>(V)>();
-      case 1:
-        return nameof_enum_impl<E, static_cast<E>(V + 1)>();
-      case 2:
-        return nameof_enum_impl<E, static_cast<E>(V + 2)>();
-      case 3:
-        return nameof_enum_impl<E, static_cast<E>(V + 3)>();
-      case 4:
-        return nameof_enum_impl<E, static_cast<E>(V + 4)>();
-      case 5:
-        return nameof_enum_impl<E, static_cast<E>(V + 5)>();
-      case 6:
-        return nameof_enum_impl<E, static_cast<E>(V + 6)>();
-      case 7:
-        return nameof_enum_impl<E, static_cast<E>(V + 7)>();
-      default:
-        return nameof_enum_impl_t<E, V + 8>{}(value);
-    }
-  }
-};
+  return enum_names;
+}
 
 template <typename E>
-struct nameof_enum_impl_t<E, NAMEOF_ENUM_RANGE> final {
-  [[nodiscard]] constexpr std::string_view operator()(int) const noexcept {
-    static_assert(std::is_enum_v<E>, "nameof::nameof_enum require enum type.");
-    return {}; // Enum variable out of range NAMEOF_ENUM_RANGE.
+[[nodiscard]] constexpr std::string_view nameof_enum_impl(int value) noexcept {
+  static_assert(std::is_enum_v<E>, "magic_enum::detail::nameof_enum_impl requires enum type.");
+  using U = std::underlying_type_t<E>;
+  constexpr int max = (enum_range<E>::max < std::numeric_limits<U>::max()) ? enum_range<E>::max : std::numeric_limits<U>::max();
+  constexpr int min = (enum_range<E>::min > std::numeric_limits<U>::min()) ? enum_range<E>::min : std::numeric_limits<U>::min();
+  constexpr auto enum_range = std::make_integer_sequence<int, max - min + 1>{};
+  constexpr auto enum_names = enum_strings_impl<E>(enum_range);
+  const int i = value - min;
+
+  if (i >= 0 && static_cast<std::size_t>(i) < enum_names.size()) {
+    return enum_names[i];
+  } else {
+    return {};
   }
-};
+}
 
 template <typename T>
 [[nodiscard]] constexpr std::string_view nameof_impl(std::string_view name, bool with_template_suffix) noexcept {
@@ -248,18 +235,7 @@ template <typename T>
 // nameof_enum(enum) obtains simple (unqualified) string enum name of enum variable.
 template <typename T, typename = std::enable_if_t<std::is_enum_v<std::decay_t<T>>>>
 [[nodiscard]] constexpr std::string_view nameof_enum(T value) noexcept {
-  constexpr bool s = std::is_signed_v<std::underlying_type_t<std::decay_t<T>>>;
-  constexpr int min = s ? -NAMEOF_ENUM_RANGE : 0;
-  if (static_cast<int>(value) >= NAMEOF_ENUM_RANGE || static_cast<int>(value) <= -NAMEOF_ENUM_RANGE) {
-    return {}; // Enum variable out of range NAMEOF_ENUM_RANGE.
-  }
-  return detail::nameof_enum_impl_t<std::decay_t<T>, min>{}(static_cast<int>(value));
-}
-
-// nameof_enum<enum>() obtains simple (unqualified) string enum name of static storage enum variable.
-template <auto V, typename = std::enable_if_t<std::is_enum_v<std::decay_t<decltype(V)>>>>
-[[nodiscard]] constexpr std::string_view nameof_enum() noexcept {
-  return detail::nameof_enum_impl<decltype(V), V>();
+  return detail::nameof_enum_impl<std::decay_t<T>>(static_cast<int>(value));
 }
 
 // nameof_type<type>() obtains string name of type.
@@ -282,9 +258,6 @@ template <typename T>
 // NAMEOF_ENUM obtains simple (unqualified) string enum name of enum variable.
 #define NAMEOF_ENUM(...) ::nameof::nameof_enum<decltype(__VA_ARGS__)>(__VA_ARGS__)
 
-// NAMEOF_CONST_ENUM obtains simple (unqualified) string enum name of static storage enum variable.
-#define NAMEOF_CONST_ENUM(...) ::nameof::nameof_enum<__VA_ARGS__>()
-
 // NAMEOF_TYPE obtains string name of type.
 #define NAMEOF_TYPE(...) ::nameof::nameof_type<__VA_ARGS__>()
 
diff --git a/test/test.cpp b/test/test.cpp
index 3378715..4bc308a 100644
--- a/test/test.cpp
+++ b/test/test.cpp
@@ -23,7 +23,6 @@
 #define CATCH_CONFIG_MAIN
 #include <catch.hpp>
 
-#define NAMEOF_ENUM_RANGE 120
 #include <nameof.hpp>
 
 #include <string>
@@ -205,11 +204,14 @@ TEST_CASE("NAMEOF_RAW") {
 
 TEST_CASE("NAMEOF_ENUM") {
 #if defined(__clang__) || (defined(__GNUC__) && __GNUC__ >= 9) || defined(_MSC_VER)
-  Color color_ = Color::BLUE;
+  constexpr Color color_ = Color::BLUE;
   Color m[3] = {Color::RED, Color::GREEN, Color::BLUE};
+
   REQUIRE(NAMEOF_ENUM(Color::RED) == "RED");
   REQUIRE(NAMEOF_ENUM(color) == "RED");
 
+  constexpr auto color_name = NAMEOF_ENUM(color_);
+  REQUIRE(color_name == "BLUE");
   REQUIRE(NAMEOF_ENUM(Color::BLUE) == "BLUE");
   REQUIRE(NAMEOF_ENUM(color_) == "BLUE");
 
@@ -218,10 +220,8 @@ TEST_CASE("NAMEOF_ENUM") {
   REQUIRE(NAMEOF_ENUM(Directions::Right) == "Right");
   REQUIRE(NAMEOF_ENUM(directions) == "Right");
 
-  REQUIRE(NAMEOF_ENUM((Color)NAMEOF_ENUM_RANGE).empty());
   REQUIRE(NAMEOF_ENUM((Color)-100).empty());
   REQUIRE(NAMEOF_ENUM((Color)100).empty());
-  REQUIRE(NAMEOF_ENUM((Directions)NAMEOF_ENUM_RANGE).empty());
   REQUIRE(NAMEOF_ENUM((Directions)100).empty());
   REQUIRE(NAMEOF_ENUM((Directions)100).empty());
 #endif
@@ -229,11 +229,14 @@ TEST_CASE("NAMEOF_ENUM") {
 
 TEST_CASE("nameof::nameof_enum(enum)") {
 #if defined(__clang__) || (defined(__GNUC__) && __GNUC__ >= 9) || defined(_MSC_VER)
-  Color color_ = Color::BLUE;
+  constexpr Color color_ = Color::BLUE;
   Color m[3] = {Color::RED, Color::GREEN, Color::BLUE};
+
   REQUIRE(nameof::nameof_enum(Color::RED) == "RED");
   REQUIRE(nameof::nameof_enum(color) == "RED");
 
+  constexpr auto color_name = nameof::nameof_enum(color_);
+  REQUIRE(color_name == "BLUE");
   REQUIRE(nameof::nameof_enum(Color::BLUE) == "BLUE");
   REQUIRE(nameof::nameof_enum(color_) == "BLUE");
 
@@ -242,63 +245,13 @@ TEST_CASE("nameof::nameof_enum(enum)") {
   REQUIRE(nameof::nameof_enum(Directions::Right) == "Right");
   REQUIRE(nameof::nameof_enum(directions) == "Right");
 
-  REQUIRE(nameof::nameof_enum((Color)NAMEOF_ENUM_RANGE).empty());
   REQUIRE(nameof::nameof_enum((Color)-100).empty());
   REQUIRE(nameof::nameof_enum((Color)100).empty());
-  REQUIRE(nameof::nameof_enum((Directions)NAMEOF_ENUM_RANGE).empty());
   REQUIRE(nameof::nameof_enum((Directions)100).empty());
   REQUIRE(nameof::nameof_enum((Directions)100).empty());
 #endif
 }
 
-TEST_CASE("NAMEOF_CONST_ENUM") {
-#if defined(__clang__) || (defined(__GNUC__) && __GNUC__ >= 9) || defined(_MSC_VER)
-  static const Color color_ = Color::BLUE;
-  constexpr Color m[3] = {Color::RED, Color::GREEN, Color::BLUE};
-  REQUIRE(NAMEOF_CONST_ENUM(Color::RED) == "RED");
-  REQUIRE(NAMEOF_CONST_ENUM(color) == "RED");
-
-  REQUIRE(NAMEOF_CONST_ENUM(Color::BLUE) == "BLUE");
-  REQUIRE(NAMEOF_CONST_ENUM(color_) == "BLUE");
-
-  REQUIRE(NAMEOF_CONST_ENUM(m[1]) == "GREEN");
-
-  REQUIRE(NAMEOF_CONST_ENUM(Directions::Right) == "Right");
-  REQUIRE(NAMEOF_CONST_ENUM(directions) == "Right");
-
-  REQUIRE(NAMEOF_CONST_ENUM((Color)NAMEOF_ENUM_RANGE).empty());
-  REQUIRE(NAMEOF_CONST_ENUM((Color)-100).empty());
-  REQUIRE(NAMEOF_CONST_ENUM((Color)100).empty());
-  REQUIRE(NAMEOF_CONST_ENUM((Directions)NAMEOF_ENUM_RANGE).empty());
-  REQUIRE(NAMEOF_CONST_ENUM((Directions)100).empty());
-  REQUIRE(NAMEOF_CONST_ENUM((Directions)100).empty());
-#endif
-}
-
-TEST_CASE("nameof::nameof_enum<enum>()") {
-#if defined(__clang__) || (defined(__GNUC__) && __GNUC__ >= 9) || defined(_MSC_VER)
-  static const Color color_ = Color::BLUE;
-  constexpr Color m[3] = {Color::RED, Color::GREEN, Color::BLUE};
-  REQUIRE(nameof::nameof_enum<Color::RED>() == "RED");
-  REQUIRE(nameof::nameof_enum<color>() == "RED");
-
-  REQUIRE(nameof::nameof_enum<Color::BLUE>() == "BLUE");
-  REQUIRE(nameof::nameof_enum<color_>() == "BLUE");
-
-  REQUIRE(nameof::nameof_enum<m[1]>() == "GREEN");
-
-  REQUIRE(nameof::nameof_enum<Directions::Right>() == "Right");
-  REQUIRE(nameof::nameof_enum<directions>() == "Right");
-
-  REQUIRE(nameof::nameof_enum<(Color)NAMEOF_ENUM_RANGE>().empty());
-  REQUIRE(nameof::nameof_enum<(Color)-100>().empty());
-  REQUIRE(nameof::nameof_enum<(Color)100>().empty());
-  REQUIRE(nameof::nameof_enum<(Directions)NAMEOF_ENUM_RANGE>().empty());
-  REQUIRE(nameof::nameof_enum<(Directions)100>().empty());
-  REQUIRE(nameof::nameof_enum<(Directions)100>().empty());
-#endif
-}
-
 TEST_CASE("NAMEOF_VAR_TYPE") {
 #if defined(__clang__)
   REQUIRE(NAMEOF_VAR_TYPE(struct_var) == "SomeStruct");