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Magic Enum C++

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

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Documentation

  • 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 = magic_enum::enum_cast<Color>(value, magic_enum::case_insensitive);
    
    // enum_cast with BinaryPredicate
    auto color = magic_enum::enum_cast<Color>(value, [](char lhs, char rhs) { return std::tolower(lhs) == std::tolower(rhs); }
    
    // enum_cast with default
    auto color_or_default = magic_enum::enum_cast<Color>(value).value_or(Color::NONE);
  • Integer to enum value

    int color_integer = 2;
    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>(value).value_or(Color::NONE);
  • 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 elements

    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 -> 1
  • Enum names sequence

    constexpr auto color_names = magic_enum::enum_names<Color>();
    // color_names -> {"RED", "BLUE", "GREEN"}
    // color_names[0] -> "RED"
  • Enum entries 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(): // ...
    // ...
    }
  • Enum switch runtime value as constexpr constant

    Color color = Color::RED;
    magic_enum::enum_switch([] (auto val) {
      constexpr Color c_color = val;
      // ...
    }, color);
  • Enum iterate for each enum as constexpr constant

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

    magic_enum::enum_contains(Color::GREEN); // -> true
    magic_enum::enum_contains<Color>(2); // -> true
    magic_enum::enum_contains<Color>(123); // -> false
    magic_enum::enum_contains<Color>("GREEN"); // -> true
    magic_enum::enum_contains<Color>("fda"); // -> false
  • Enum index in sequence

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

    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;
    };
    
    magic_enum::enum_flags_name(Directions::Up | Directions::Right); // -> "Directions::Up|Directions::Right"
    magic_enum::enum_flags_contains(Directions::Up | Directions::Right); // -> true
    magic_enum::enum_flags_cast(3); // -> "Directions::Left|Directions::Down"
  • Enum type name

    Color color = Color::RED;
    auto type_name = magic_enum::enum_type_name<decltype(color)>();
    // type_name -> "Color"
  • IOstream operator for enum

    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 operator for enum

    enum class Flags { A = 1 << 0, B = 1 << 1, C = 1 << 2, D = 1 << 3 };
    using namespace magic_enum::bitwise_operators; // out-of-the-box bitwise operators for enums.
    // Support operators: ~, |, &, ^, |=, &=, ^=.
    Flags flags = Flags::A | Flags::B & ~Flags::C;
  • Checks whether type is an Unscoped enumeration.

    enum color { red, green, blue };
    enum class direction { left, right };
    
    magic_enum::is_unscoped_enum<color>::value -> true
    magic_enum::is_unscoped_enum<direction>::value -> false
    magic_enum::is_unscoped_enum<int>::value -> false
    
    // Helper variable template.
    magic_enum::is_unscoped_enum_v<color> -> true
  • Checks whether type is an Scoped enumeration.

    enum color { red, green, blue };
    enum class direction { left, right };
    
    magic_enum::is_scoped_enum<color>::value -> false
    magic_enum::is_scoped_enum<direction>::value -> true
    magic_enum::is_scoped_enum<int>::value -> false
    
    // Helper variable template.
    magic_enum::is_scoped_enum_v<direction> -> true
  • Static storage enum variable to string This version is much lighter on the compile times and is not restricted to the 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.

    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_red_green {Color::RED|Color::GREEN};
    bool all = color_bitset_red_green.all();
    // all -> false
    // Color::BLUE is missing
    bool test = color_bitset_red_green.test(Color::RED);
    // test -> true
  • 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
  • Improved UB-free "SFINAE-friendly" underlying_type.

    magic_enum::underlying_type<color>::type -> int
    
    // Helper types.
    magic_enum::underlying_type_t<Direction> -> int

Remarks

  • magic_enum does not pretend to be a silver bullet for reflection for enums, it was originally designed for small enum.

  • Before use, read the limitations of functionality.

Integration

  • You should add the required file magic_enum.hpp, and optionally other headers from include dir or release archive. Alternatively, you can build the library with CMake.

  • If you are using vcpkg on your project for external dependencies, then you can use the magic-enum package.

  • If you are using Conan to manage your dependencies, merely add magic_enum/x.y.z to your conan's requires, where x.y.z is the release version you want to use.

  • If you are using Build2 to build and manage your dependencies, add depends: magic_enum ^x.y.z to the manifest file where x.y.z is the release version you want to use. You can then import the target using magic_enum%lib{magic_enum}.

  • Alternatively, you can use something like CPM which is based on CMake's Fetch_Content module.

    CPMAddPackage(
        NAME magic_enum
        GITHUB_REPOSITORY Neargye/magic_enum
        GIT_TAG x.y.z # Where `x.y.z` is the release version you want to use.
    )
  • Bazel is also supported, simply add to your WORKSPACE file:

    http_archive(
        name = "magic_enum",
        strip_prefix = "magic_enum-<commit>",
        urls = ["https://github.com/Neargye/magic_enum/archive/<commit>.zip"],
    )
    

    To use bazel inside the repository it's possible to do:

    bazel build //...
    bazel test //...
    bazel run //example
    

    (Note that you must use a supported compiler or specify it with export CC= <compiler>.)

  • If you are using Ros, you can include this package by adding <depend>magic_enum</depend> to your package.xml and include this package in your workspace. In your CMakeLists.txt add the following:

    find_package(magic_enum CONFIG REQUIRED)
    ...
    target_link_libraries(your_executable magic_enum::magic_enum)

Compiler compatibility

  • Clang/LLVM >= 5
  • MSVC++ >= 14.11 / Visual Studio >= 2017
  • Xcode >= 10
  • GCC >= 9
  • MinGW >= 9

Licensed under the MIT License