From 6653bd71994d7866ce79de61b12a2261e6451ea0 Mon Sep 17 00:00:00 2001
From: Pokechu22 <Pokechu022@gmail.com>
Date: Wed, 10 Feb 2021 12:46:32 -0800
Subject: [PATCH] Create EnumFormatter

---
 Source/Core/Common/CMakeLists.txt             |  1 +
 Source/Core/Common/EnumFormatter.h            | 91 +++++++++++++++++++
 Source/Core/DolphinLib.props                  |  1 +
 Source/UnitTests/Common/CMakeLists.txt        |  1 +
 Source/UnitTests/Common/EnumFormatterTest.cpp | 67 ++++++++++++++
 Source/UnitTests/UnitTests.vcxproj            |  1 +
 6 files changed, 162 insertions(+)
 create mode 100644 Source/Core/Common/EnumFormatter.h
 create mode 100644 Source/UnitTests/Common/EnumFormatterTest.cpp

diff --git a/Source/Core/Common/CMakeLists.txt b/Source/Core/Common/CMakeLists.txt
index 4a3623d4e8..9f7486a571 100644
--- a/Source/Core/Common/CMakeLists.txt
+++ b/Source/Core/Common/CMakeLists.txt
@@ -42,6 +42,7 @@ add_library(common
   DynamicLibrary.h
   ENetUtil.cpp
   ENetUtil.h
+  EnumFormatter.h
   Event.h
   FileSearch.cpp
   FileSearch.h
diff --git a/Source/Core/Common/EnumFormatter.h b/Source/Core/Common/EnumFormatter.h
new file mode 100644
index 0000000000..2ca1bb114e
--- /dev/null
+++ b/Source/Core/Common/EnumFormatter.h
@@ -0,0 +1,91 @@
+// Copyright 2021 Dolphin Emulator Project
+// Licensed under GPLv2+
+// Refer to the license.txt file included.
+
+#pragma once
+
+#include <array>
+#include <fmt/format.h>
+#include <type_traits>
+
+/*
+ * Helper for using enums with fmt.
+ *
+ * Usage example:
+ *
+ * enum class Foo
+ * {
+ *   A = 0,
+ *   B = 1,
+ *   C = 2,
+ * };
+ *
+ * template <>
+ * struct fmt::formatter<Foo> : EnumFormatter<Foo::C>
+ * {
+ *   formatter() : EnumFormatter({"A", "B", "C"}) {}
+ * };
+ *
+ * enum class Bar
+ * {
+ *   D = 0,
+ *   E = 1,
+ *   F = 3,
+ * };
+ *
+ * template <>
+ * struct fmt::formatter<Bar> : EnumFormatter<Bar::F>
+ * {
+ *   // using std::array here fails due to nullptr not being const char*, at least in MSVC
+ *   // (but only when a field is used; directly in the constructor is OK)
+ *   static constexpr array_type names = {"D", "E", nullptr, "F"};
+ *   formatter() : EnumFormatter(names) {}
+ * };
+ */
+template <auto last_member, typename T = decltype(last_member),
+          size_t size = static_cast<size_t>(last_member) + 1,
+          std::enable_if_t<std::is_enum_v<T>, bool> = true>
+class EnumFormatter
+{
+public:
+  constexpr auto parse(fmt::format_parse_context& ctx)
+  {
+    auto it = ctx.begin(), end = ctx.end();
+    // 'u' for user display, 's' for shader generation
+    if (it != end && (*it == 'u' || *it == 's'))
+      formatting_for_shader = (*it++ == 's');
+    return it;
+  }
+
+  template <typename FormatContext>
+  auto format(const T& e, FormatContext& ctx)
+  {
+    const auto value = static_cast<std::underlying_type_t<T>>(e);
+
+    if (!formatting_for_shader)
+    {
+      if (value >= 0 && value < size && m_names[value] != nullptr)
+        return fmt::format_to(ctx.out(), "{} ({})", m_names[value], value);
+      else
+        return fmt::format_to(ctx.out(), "Invalid ({})", value);
+    }
+    else
+    {
+      if (value >= 0 && value < size && m_names[value] != nullptr)
+        return fmt::format_to(ctx.out(), "{:#x}u /* {} */", value, m_names[value]);
+      else
+        return fmt::format_to(ctx.out(), "{:#x}u /* Invalid */",
+                              static_cast<std::make_unsigned_t<T>>(value));
+    }
+  }
+
+protected:
+  // This is needed because std::array deduces incorrectly if nullptr is included in the list
+  using array_type = std::array<const char*, size>;
+
+  constexpr explicit EnumFormatter(const array_type names) : m_names(std::move(names)) {}
+
+private:
+  const array_type m_names;
+  bool formatting_for_shader = false;
+};
diff --git a/Source/Core/DolphinLib.props b/Source/Core/DolphinLib.props
index d78534993a..638e6734e2 100644
--- a/Source/Core/DolphinLib.props
+++ b/Source/Core/DolphinLib.props
@@ -45,6 +45,7 @@
     <ClInclude Include="Common\DebugInterface.h" />
     <ClInclude Include="Common\DynamicLibrary.h" />
     <ClInclude Include="Common\ENetUtil.h" />
+    <ClInclude Include="Common\EnumFormatter.h" />
     <ClInclude Include="Common\Event.h" />
     <ClInclude Include="Common\FileSearch.h" />
     <ClInclude Include="Common\FileUtil.h" />
diff --git a/Source/UnitTests/Common/CMakeLists.txt b/Source/UnitTests/Common/CMakeLists.txt
index 120fee6c33..86d9dedfcf 100644
--- a/Source/UnitTests/Common/CMakeLists.txt
+++ b/Source/UnitTests/Common/CMakeLists.txt
@@ -5,6 +5,7 @@ add_dolphin_test(BlockingLoopTest BlockingLoopTest.cpp)
 add_dolphin_test(BusyLoopTest BusyLoopTest.cpp)
 add_dolphin_test(CommonFuncsTest CommonFuncsTest.cpp)
 add_dolphin_test(CryptoEcTest Crypto/EcTest.cpp)
+add_dolphin_test(EnumFormatterTest EnumFormatterTest.cpp)
 add_dolphin_test(EventTest EventTest.cpp)
 add_dolphin_test(FixedSizeQueueTest FixedSizeQueueTest.cpp)
 add_dolphin_test(FlagTest FlagTest.cpp)
diff --git a/Source/UnitTests/Common/EnumFormatterTest.cpp b/Source/UnitTests/Common/EnumFormatterTest.cpp
new file mode 100644
index 0000000000..fb713db2f2
--- /dev/null
+++ b/Source/UnitTests/Common/EnumFormatterTest.cpp
@@ -0,0 +1,67 @@
+// Copyright 2021 Dolphin Emulator Project
+// Licensed under GPLv2+
+// Refer to the license.txt file included.
+
+#include <gtest/gtest.h>
+
+#include "Common/CommonTypes.h"
+#include "Common/EnumFormatter.h"
+
+enum class Enum1 : u32
+{
+  A = 0,
+  B = 1,
+  C = 2,
+};
+
+template <>
+struct fmt::formatter<Enum1> : EnumFormatter<Enum1::C>
+{
+  formatter() : EnumFormatter({"A", "B", "C"}) {}
+};
+
+enum class Enum2 : s32
+{
+  D = 0,
+  E = 1,
+  F = 3,
+};
+
+template <>
+struct fmt::formatter<Enum2> : EnumFormatter<Enum2::F>
+{
+  static constexpr array_type names = {"D", "E", nullptr, "F"};
+  formatter() : EnumFormatter(names) {}
+};
+
+TEST(EnumUtil, Enum1)
+{
+  EXPECT_EQ(fmt::to_string(Enum1::A), "A (0)");
+  EXPECT_EQ(fmt::to_string(Enum1::B), "B (1)");
+  EXPECT_EQ(fmt::to_string(Enum1::C), "C (2)");
+  EXPECT_EQ(fmt::to_string(static_cast<Enum1>(3)), "Invalid (3)");
+  EXPECT_EQ(fmt::to_string(static_cast<Enum1>(4)), "Invalid (4)");
+
+  EXPECT_EQ(fmt::format("{:s}", Enum1::A), "0x0u /* A */");
+  EXPECT_EQ(fmt::format("{:s}", Enum1::B), "0x1u /* B */");
+  EXPECT_EQ(fmt::format("{:s}", Enum1::C), "0x2u /* C */");
+  EXPECT_EQ(fmt::format("{:s}", static_cast<Enum1>(3)), "0x3u /* Invalid */");
+  EXPECT_EQ(fmt::format("{:s}", static_cast<Enum1>(4)), "0x4u /* Invalid */");
+}
+
+TEST(EnumUtil, Enum2)
+{
+  EXPECT_EQ(fmt::to_string(Enum2::D), "D (0)");
+  EXPECT_EQ(fmt::to_string(Enum2::E), "E (1)");
+  EXPECT_EQ(fmt::to_string(static_cast<Enum2>(2)), "Invalid (2)");
+  EXPECT_EQ(fmt::to_string(Enum2::F), "F (3)");
+  EXPECT_EQ(fmt::to_string(static_cast<Enum2>(4)), "Invalid (4)");
+  EXPECT_EQ(fmt::to_string(static_cast<Enum2>(-1)), "Invalid (-1)");
+
+  EXPECT_EQ(fmt::format("{:s}", Enum2::D), "0x0u /* D */");
+  EXPECT_EQ(fmt::format("{:s}", Enum2::E), "0x1u /* E */");
+  EXPECT_EQ(fmt::format("{:s}", static_cast<Enum2>(2)), "0x2u /* Invalid */");
+  EXPECT_EQ(fmt::format("{:s}", Enum2::F), "0x3u /* F */");
+  EXPECT_EQ(fmt::format("{:s}", static_cast<Enum2>(4)), "0x4u /* Invalid */");
+  EXPECT_EQ(fmt::format("{:s}", static_cast<Enum2>(-1)), "0xffffffffu /* Invalid */");
+}
diff --git a/Source/UnitTests/UnitTests.vcxproj b/Source/UnitTests/UnitTests.vcxproj
index 230ac50412..d0b0c27fb6 100644
--- a/Source/UnitTests/UnitTests.vcxproj
+++ b/Source/UnitTests/UnitTests.vcxproj
@@ -49,6 +49,7 @@
     <ClCompile Include="Common\BusyLoopTest.cpp" />
     <ClCompile Include="Common\CommonFuncsTest.cpp" />
     <ClCompile Include="Common\Crypto\EcTest.cpp" />
+    <ClCompile Include="Common\EnumFormatterTest.cpp" />
     <ClCompile Include="Common\EventTest.cpp" />
     <ClCompile Include="Common\FixedSizeQueueTest.cpp" />
     <ClCompile Include="Common\FlagTest.cpp" />