magic_enum

Static reflection for enums (to string, from string, iteration) for modern C++, work with any enum type without any macro or boilerplate code

Neargye

2602

225

C++

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

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 = 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