Magic Enum C++

Header-only C++17 library provides static reflection for enums, work with any enum type without any macro or boilerplate code.

Documentation

• Reference
• Limitations
• Integration

Features & Examples

• Basic

  #include <magic_enum/magic_enum.hpp>
  #include <iostream>
  
  enum class Color { RED = -10, BLUE = 0, GREEN = 10 };
  
  int main() {
    Color c1 = Color::RED;
    std::cout << magic_enum::enum_name(c1) << std::endl; // RED
    return 0;
  }

• Enum value to string

  Color color = Color::RED;
  auto color_name = magic_enum::enum_name(color);
  // color_name -> "RED"

• String to enum value

  std::string color_name{"GREEN"};
  auto color = magic_enum::enum_cast<Color>(color_name);
  if (color.has_value()) {
    // color.value() -> Color::GREEN
  }
  
  // case insensitive enum_cast
  auto color_case_insensitive = magic_enum::enum_cast<Color>(color_name, magic_enum::case_insensitive);
  
  // enum_cast with BinaryPredicate
  auto color_with_predicate = magic_enum::enum_cast<Color>(color_name, [](char lhs, char rhs) { return std::tolower(static_cast<unsigned char>(lhs)) == std::tolower(static_cast<unsigned char>(rhs)); });
  
  // enum_cast with default
  auto color_or_default = magic_enum::enum_cast<Color>(color_name).value_or(Color::RED);

• Integer to enum value

  int color_integer = 0;
  auto color = magic_enum::enum_cast<Color>(color_integer);
  if (color.has_value()) {
    // color.value() -> Color::BLUE
  }
  
  auto color_or_default = magic_enum::enum_cast<Color>(123).value_or(Color::RED);

• Indexed access to enum value

  std::size_t i = 0;
  Color color = magic_enum::enum_value<Color>(i);
  // color -> Color::RED

• Enum value sequence

  constexpr auto colors = magic_enum::enum_values<Color>();
  // colors -> {Color::RED, Color::BLUE, Color::GREEN}
  // colors[0] -> Color::RED

• Number of enum values

  constexpr std::size_t color_count = magic_enum::enum_count<Color>();
  // color_count -> 3

• Enum value to integer

  Color color = Color::RED;
  auto color_integer = magic_enum::enum_integer(color); // or magic_enum::enum_underlying(color);
  // color_integer -> -10

• Enum name sequence

  constexpr auto color_names = magic_enum::enum_names<Color>();
  // color_names -> {"RED", "BLUE", "GREEN"}
  // color_names[0] -> "RED"

• Enum entry sequence

  constexpr auto color_entries = magic_enum::enum_entries<Color>();
  // color_entries -> {{Color::RED, "RED"}, {Color::BLUE, "BLUE"}, {Color::GREEN, "GREEN"}}
  // color_entries[0].first -> Color::RED
  // color_entries[0].second -> "RED"

• Enum fusion for multi-level switch/case statements

  switch (magic_enum::enum_fuse(color, direction).value()) {
    case magic_enum::enum_fuse(Color::RED, Directions::Up).value(): // ...
    case magic_enum::enum_fuse(Color::BLUE, Directions::Down).value(): // ...
  // ...
  }

• Runtime enum value as constexpr constant

  Color color = Color::RED;
  magic_enum::enum_switch([](auto val) {
    constexpr Color c_color = val;
    // ...
  }, color);

• Iterate over enum values as constexpr constants

  magic_enum::enum_for_each<Color>([](auto val) {
    constexpr Color c_color = val;
    // ...
  });

• Move through enum values

  magic_enum::enum_next_value(Color::RED);          // -> optional containing Color::BLUE
  magic_enum::enum_prev_value_circular(Color::RED); // -> Color::GREEN

• Check whether enum contains value

  magic_enum::enum_contains(Color::GREEN); // -> true
  magic_enum::enum_contains<Color>(0); // -> true
  magic_enum::enum_contains<Color>(123); // -> false
  magic_enum::enum_contains<Color>("GREEN"); // -> true
  magic_enum::enum_contains<Color>("fda"); // -> false

• Check whether value is in reflection range

  magic_enum::enum_reflected<Color>(123); // -> true
  magic_enum::enum_contains<Color>(123);  // -> false
  magic_enum::enum_reflected<Color>(128); // -> false

• Enum index in sequence

  constexpr auto color_index = magic_enum::enum_index(Color::BLUE);
  // color_index.value() -> 1
  // color_index.has_value() -> true

• Flag operations

  enum Directions : std::uint64_t {
    Left = 1,
    Down = 2,
    Up = 4,
    Right = 8,
  };
  template <>
  struct magic_enum::customize::enum_range<Directions> {
    static constexpr bool is_flags = true;
  };
  using namespace magic_enum::bitwise_operators; // Use with care; operators are enabled for all enums.
  
  magic_enum::enum_flags_name(Directions::Up | Directions::Right); // -> "Up|Right"
  magic_enum::enum_flags_name(Directions::Up | Directions::Right, ','); // -> "Up,Right"
  magic_enum::enum_flags_contains(Directions::Up | Directions::Right); // -> true
  magic_enum::enum_flags_cast<Directions>(3).value(); // -> Directions::Left|Directions::Down
  magic_enum::enum_flags_cast<Directions>("Left,Down", ',').value(); // -> Directions::Left|Directions::Down
  magic_enum::enum_flags_test(Directions::Up | Directions::Right, Directions::Up); // -> true
  magic_enum::enum_flags_test_any(Directions::Left | Directions::Down, Directions::Down | Directions::Right); // -> true
  magic_enum::is_flags_v<Directions>; // -> true

• Enum type name

  Color color = Color::RED;
  auto type_name = magic_enum::enum_type_name<decltype(color)>();
  // type_name -> "Color"

• I/O stream operators for enums

  using magic_enum::iostream_operators::operator<<; // out-of-the-box ostream operators for enums.
  Color color = Color::BLUE;
  std::cout << color << std::endl; // "BLUE"

  using magic_enum::iostream_operators::operator>>; // out-of-the-box istream operators for enums.
  Color color;
  std::cin >> color;

• Bitwise operators for enums

  enum class Flags { A = 1 << 0, B = 1 << 1, C = 1 << 2, D = 1 << 3 };
  using namespace magic_enum::bitwise_operators; // Use with care; operators are enabled for all enums.
  // Support operators: ~, |, &, ^, |=, &=, ^=.
  Flags flags = Flags::A | (Flags::B & ~Flags::C);

• Formatting

  #include <format>
  #include <magic_enum/magic_enum_format.hpp>
  
  std::format("{}", Color::RED); // -> "RED"
  std::format("{}", Color{42});  // -> "42"

  Include {fmt} before magic_enum_format.hpp to enable {fmt} formatter support.

• Unscoped enum trait

  enum color { red, green, blue };
  enum class direction { left, right };
  
  magic_enum::is_unscoped_enum_v<color> -> true
  magic_enum::is_unscoped_enum_v<direction> -> false

• Scoped enum trait

  enum color { red, green, blue };
  enum class direction { left, right };
  
  magic_enum::is_scoped_enum_v<color> -> false
  magic_enum::is_scoped_enum_v<direction> -> true

• Compile-time enum value to string. This overload compiles faster and is not restricted by enum_range limitation.

  constexpr Color color = Color::BLUE;
  constexpr auto color_name = magic_enum::enum_name<color>();
  // color_name -> "BLUE"

• containers::array array container for enums.

  constexpr auto color_rgb_values = magic_enum::containers::make_array<Color>(RGB{255, 0, 0}, RGB{0, 255, 0}, RGB{0, 0, 255});
  
  magic_enum::containers::array<Color, RGB> color_rgb_array {};
  color_rgb_array[Color::RED] = {255, 0, 0};
  color_rgb_array[Color::GREEN] = {0, 255, 0};
  color_rgb_array[Color::BLUE] = {0, 0, 255};
  magic_enum::containers::get<Color::BLUE>(color_rgb_array); // -> RGB{0, 0, 255}

• containers::bitset bitset container for enums.

  constexpr magic_enum::containers::bitset<Color> color_bitset {Color::RED, Color::GREEN};
  color_bitset.test(Color::RED);  // -> true
  color_bitset.test(Color::BLUE); // -> false
  
  std::uint8_t incoming = 0b00000011;
  auto raw_bitset = magic_enum::containers::bitset<Color> {magic_enum::containers::raw_access, incoming};

• containers::set set container for enums.

  auto color_set = magic_enum::containers::set<Color>();
  bool empty = color_set.empty();
  // empty -> true
  color_set.insert(Color::GREEN);
  color_set.insert(Color::BLUE);
  color_set.insert(Color::RED);
  std::size_t size = color_set.size();
  // size -> 3
  
  using color_name_set = magic_enum::containers::set<Color, magic_enum::containers::name_less<>>;
  color_name_set colors_by_name {Color::RED, Color::GREEN, Color::BLUE};

• Underlying type

  magic_enum::underlying_type<Color>::type -> int
  magic_enum::underlying_type_t<Color> -> int

Integration

• Copy required headers from include/magic_enum or use release archive. magic_enum_all.hpp includes all public headers.

• Use CMake with add_subdirectory or find_package(magic_enum CONFIG REQUIRED), then link magic_enum::magic_enum.

• Use vcpkg, Conan, Build2, or Meson.

• Fetch sources with CMake FetchContent or CPM.cmake. Release tags use vx.y.z format.

• Use Bazel with MODULE.bazel or http_archive; target is @magic_enum//:magic_enum.

• Use ROS with <depend>magic_enum</depend> in package.xml, then link magic_enum::magic_enum.

• CMake targets:

  • magic_enum::magic_enum is the header-only target.
  • magic_enum::magic_enum_module is the C++20 module target. Enable it with MAGIC_ENUM_USE_MODULES=ON. CMake 3.28+ is required.

  Build the module target:

  cmake -S . -B build -G Ninja -DMAGIC_ENUM_USE_MODULES=ON
  cmake --build build

  Link the module target:

  find_package(magic_enum CONFIG REQUIRED)
  target_link_libraries(your_executable PRIVATE magic_enum::magic_enum_module)
  set_target_properties(your_executable PROPERTIES CXX_EXTENSIONS OFF CXX_SCAN_FOR_MODULES ON)

  Import the module:

  import magic_enum;
  
  enum class Color { RED, GREEN, BLUE };
  auto name = magic_enum::enum_name(Color::RED); // "RED"

  Do not use #include <magic_enum/...> and import magic_enum; in the same program. Use the same compiler, standard library, and C++ standard when building and consuming an installed module. The pkg-config package supports only the header-only target.

  Optional settings:

  • Set MAGIC_ENUM_MODULE_WITH_FMT=ON to enable {fmt} support through fmt::fmt. It is disabled by default. The {fmt} C++ module is not supported.
  • Set MAGIC_ENUM_MODULE_IMPORT_STD=ON to enable import std support. This requires a compatible CMake toolchain.

Header-only compiler compatibility

• Clang/LLVM >= 5
• MSVC++ >= 15.3 / Visual Studio >= 2017
• Xcode >= 10
• GCC >= 9

Licensed under the MIT License