Magic Enum C++

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|  \/  |           (_)      |  ____|                        / ____|_     _
| \  / | __ _  __ _ _  ___  | |__   _ __  _   _ _ __ ___   | |   _| |_ _| |_
| |\/| |/ _` |/ _` | |/ __| |  __| | '_ \| | | | '_ ` _ \  | |  |_   _|_   _|
| |  | | (_| | (_| | | (__  | |____| | | | |_| | | | | | | | |____|_|   |_|
|_|  |_|\__,_|\__, |_|\___| |______|_| |_|\__,_|_| |_| |_|  \_____|
               __/ |
              |___/

What is Magic Enum?

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

enum_cast obtains enum value from string or integer.
enum_value returns enum value at specified index.
enum_values obtains enum value sequence.
enum_count returns number of enum values.
enum_integer obtains integer value from enum value.
enum_name returns string name from enum value.
enum_names obtains string enum name sequence.
enum_entries obtains pair (value enum, string enum name) sequence.
is_unscoped_enum checks whether type is an Unscoped enumeration.
is_scoped_enum checks whether type is an Scoped enumeration.

Features

C++17
Header-only
Dependency-free
Compile-time
Enum to string
String to enum
Iterating over enum

Examples

// For example color enum.
enum Color { RED = 2, BLUE = 4, GREEN = 8 };

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
}

Integer to enum value

int color_integer = 2;
auto color = magic_enum::enum_cast<Color>(color_integer);
if (colo.has_value()) {
  // color.value() -> Color::RED
}

Indexed access to enum value

int i = 1;
Color colo = magic_enum::enum_value<Color>(i);
// color -> Color::BLUE

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);
// color -> 2

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"

Stream operator for enum

using namespace magic_enum::ops; // out-of-the-box stream operator for enums.
Color color = Color::BLUE;
std::cout << color << std::endl; // "BLUE"

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

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

Remarks

magic_enum::enum_cast(value) returns std::optional<E>, using has_value() to check contains enum value and value() to get the enum value.
magic_enum::enum_value(index) no bounds checking is performed: the behavior is undefined if index >= number of enum values.
magic_enum::enum_values<E>() returns std::array<E, N> with all enum value where N = number of enum values, sorted by enum value.
magic_enum::enum_name(value) returns std::string_view. If enum value does not have name, returns empty string.
magic_enum::enum_name<value>() is much lighter on the compile times and is not restricted to the enum_range limitation.
magic_enum::enum_names<E>() returns std::array<std::string_view, N> with all string enum name where N = number of enum values, sorted by enum value.
magic_enum::enum_entries<E>() returns std::array<std::pair<E, std::string_view>, N> with all std::pair (value enum, string enum name) where N = number of enum values, sorted by enum value.
Enum value must be in range [MAGIC_ENUM_RANGE_MIN, MAGIC_ENUM_RANGE_MAX]. By default MAGIC_ENUM_RANGE_MIN = -128, MAGIC_ENUM_RANGE_MAX = 128.

If need another range for all enum types by default, redefine the macro MAGIC_ENUM_RANGE_MIN and MAGIC_ENUM_RANGE_MAX.
```
#define MAGIC_ENUM_RANGE_MIN 0
#define MAGIC_ENUM_RANGE_MAX 256
#include <magic_enum.hpp>
```
If need another range for specific enum type, add specialization enum_range for necessary enum type.
```
#include <magic_enum.hpp>

enum number { one = 100, two = 200, three = 300 };

namespace magic_enum {
template <>
struct enum_range<number> {
  static constexpr int min = 100;
  static constexpr int max = 300;
};
}
```

magic_enum obtains the first defined value enums, and won't work if value are aliased.

enum ShapeKind {
  ConvexBegin = 0,
  Box = 0, // Won't work.
  Sphere = 1,
  ConvexEnd = 2,
  Donut = 2, // Won't work too.
  Banana = 3,
  COUNT = 4,
};
// magic_enum::enum_cast<ShapeKind>("Box") -> std::nullopt
// magic_enum::enum_name(ShapeKind::Box) -> "ConvexBegin"

Work around the issue:

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,
};
// magic_enum::enum_cast<ShapeKind>("Box") -> ShapeKind::Box
// magic_enum::enum_name(ShapeKind::Box) -> "Box"

// Non-reflected aliases.
// magic_enum::enum_cast<ShapeKind>("ConvexBegin") -> std::nullopt
// magic_enum::enum_name(ShapeKind::ConvexBegin) -> "Box"

machadodev/magic_enum

Magic Enum C++

What is Magic Enum?

Features

Examples

Remarks

Integration

Compiler compatibility

Licensed under the MIT License