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245 lines
7.3 KiB
Markdown
245 lines
7.3 KiB
Markdown
# Magic Enum C++
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```text
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__ __ _ ______ _____
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| \/ | (_) | ____| / ____|_ _
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| \ / | __ _ __ _ _ ___ | |__ _ __ _ _ _ __ ___ | | _| |_ _| |_
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| |\/| |/ _` |/ _` | |/ __| | __| | '_ \| | | | '_ ` _ \ | | |_ _|_ _|
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| | | | (_| | (_| | | (__ | |____| | | | |_| | | | | | | | |____|_| |_|
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|_| |_|\__,_|\__, |_|\___| |______|_| |_|\__,_|_| |_| |_| \_____|
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__/ |
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|___/
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```
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[](https://github.com/Neargye/magic_enum/releases)
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[](LICENSE)
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[](https://travis-ci.org/Neargye/magic_enum)
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[](https://ci.appveyor.com/project/Neargye/magic-enum-hf8vk/branch/master)
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[](https://www.codacy.com/app/Neargye/magic_enum?utm_source=github.com&utm_medium=referral&utm_content=Neargye/magic_enum&utm_campaign=Badge_Grade)
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[](https://wandbox.org/permlink/jPWeZxV1UcqvudZr)
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## What is Magic Enum?
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Header-only C++17 library provides static reflection on enums, work with any enum type without any macro or boilerplate code.
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* `enum_cast` obtains enum value from string or integer.
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* `enum_value` returns enum value at specified index.
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* `enum_values` obtains enum value sequence.
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* `enum_count` returns number of enum values.
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* `enum_name` obtains string name from enum value.
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* `enum_names` obtains string enum name sequence.
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* `is_unscoped_enum` checks whether type is an Unscoped enumeration.
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* `is_scoped_enum` checks whether type is an Scoped enumeration.
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## Features
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* C++17
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* Header-only
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* Dependency-free
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* Compile-time
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* Static reflection on enums
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* Enum to string
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* String to enum
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* Work with any enum type
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* Without any macro or boilerplate code
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## [Examples](example/example.cpp)
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```cpp
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// For example color enum.
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enum Color { RED = 2, BLUE = 4, GREEN = 8 };
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```
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* Enum value to string
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```cpp
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Color color = Color::RED;
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auto color_name = magic_enum::enum_name(color);
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if (color_name.has_value()) {
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// color_name.value() -> "RED"
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}
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```
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* Static storage enum variable to string
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```cpp
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constexpr Color color = Color::BLUE;
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constexpr auto color_name = magic_enum::enum_name(color);
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if (color_name.has_value()) {
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// color_name.value() -> "BLUE"
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}
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```
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* String to enum value
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```cpp
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std::string color_name{"GREEN"};
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auto color = magic_enum::enum_cast<Color>(color_name);
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if (color.has_value()) {
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// color.value() -> Color::GREEN
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}
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```
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* Static storage string to enum value
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```cpp
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constexpr auto color = magic_enum::enum_cast<Color>("BLUE");
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if (color.has_value()) {
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// color.value() -> Color::BLUE
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}
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```
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* Integer to enum value
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```cpp
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int color_value = 2;
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auto color = magic_enum::enum_cast<Color>(color_value);
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if (colo.has_value()) {
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// color.value() -> Color::RED
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}
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```
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* Static storage integer to enum value
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```cpp
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constexpr auto color = magic_enum::enum_cast<Color>(4);
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if (color.has_value()) {
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// color.value() -> Color::BLUE
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}
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```
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* Indexed access to enum value
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```cpp
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int i = 1;
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Color colo = magic_enum::enum_value<Color>(i);
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// color -> Color::BLUE
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```
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* Compile-time indexed access.
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```cpp
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constexpr Color color = magic_enum::enum_value<Color>(0);
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// color -> Color::RED
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```
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* Enum value sequence
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```cpp
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constexpr auto colors = magic_enum::enum_values<Color>();
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// colors -> {Color::RED, Color::BLUE, Color::GREEN}
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```
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* Number of enum elements
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```cpp
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constexpr std::size_t color_count = magic_enum::enum_count<Color>();
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// color_count -> 3
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```
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* Enum names sequence
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```cpp
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constexpr auto color_names = magic_enum::enum_names<Color>();
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// color_names -> {"RED", "BLUE", "GREEN"}
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```
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* Stream operator for enum
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```cpp
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using namespace magic_enum::ops; // out-of-the-box stream operator for enums.
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Color color = Color::BLUE;
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std::cout << color << std::endl; // "BLUE"
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```
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* Checks whether type is an Unscoped enumeration.
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```cpp
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enum сolor { red, green, blue };
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enum class direction { left, right };
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magic_enum::is_unscoped_enum<color>::value -> true
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magic_enum::is_unscoped_enum<direction>::value -> false
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magic_enum::is_unscoped_enum<int>::value -> false
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// Helper variable template.
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magic_enum::is_unscoped_enum_v<color> -> true
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```
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* Checks whether type is an Scoped enumeration.
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```cpp
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enum сolor { red, green, blue };
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enum class direction { left, right };
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magic_enum::is_scoped_enum<color>::value -> false
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magic_enum::is_scoped_enum<direction>::value -> true
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magic_enum::is_scoped_enum<int>::value -> false
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// Helper variable template.
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magic_enum::is_scoped_enum_v<direction> -> true
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```
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## Remarks
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* `magic_enum::enum_cast` returns `std::optional<E>`, using `has_value()` to check contains enum value and `value()` to get the enum value.
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* `magic_enum::enum_value` no bounds checking is performed: the behavior is undefined if `index >= number of enum values`.
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* `magic_enum::enum_values` returns `std::array<E, N>` with all enum value where `N = number of enum values`, sorted by enum value.
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* `magic_enum::enum_name` returns `std::optional<std::string_view>`, using `has_value()` to check contains enum name and `value()` to get the enum name.
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* `magic_enum::enum_names` returns `std::array<std::string_view, N>` with all string enum name where `N = number of enum values`, sorted by enum value.
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* Enum value must be in range `[-256, 256]`. If you need another range, add specialization enum_range for necessary enum type.
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```cpp
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#include <magic_enum.hpp>
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enum number { one = 100, two = 200, three = 300 };
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namespace magic_enum {
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template <>
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struct enum_range<number> {
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static constexpr int min = 100;
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static constexpr int max = 300;
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};
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}
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```
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* `magic_enum::enum_cast` and `magic_enum::enum_name` obtains the first defined value enums, and won't work if value are aliased.
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```cpp
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enum ShapeKind {
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ConvexBegin = 0,
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Box = 0, // Won't work.
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Sphere = 1,
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ConvexEnd = 2,
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Donut = 2, // Won't work too.
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Banana = 3,
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COUNT = 4,
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};
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// magic_enum::enum_cast<ShapeKind>("Box") -> std::nullopt
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// magic_enum::enum_name(ShapeKind::Box) -> "ConvexBegin"
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```
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Work around the issue:
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```cpp
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enum ShapeKind {
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// Convex shapes, see ConvexBegin and ConvexEnd below.
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Box = 0,
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Sphere = 1,
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// Non-convex shapes.
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Donut = 2,
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Banana = 3,
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COUNT = Banana + 1,
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// Non-reflected aliases.
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ConvexBegin = Box,
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ConvexEnd = Sphere + 1,
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};
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// magic_enum::enum_cast<ShapeKind>("Box") -> ShapeKind::Box
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// magic_enum::enum_name(ShapeKind::Box) -> "Box"
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// Non-reflected aliases.
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// magic_enum::enum_cast<ShapeKind>("ConvexBegin") -> std::nullopt
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// magic_enum::enum_name(ShapeKind::ConvexBegin) -> "Box"
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```
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## Integration
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You should add the required file [magic_enum.hpp](include/magic_enum.hpp).
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## Compiler compatibility
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* Clang/LLVM >= 5
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* Visual C++ >= 15.3 / Visual Studio >= 2017
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* Xcode >= 10.2
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* GCC >= 9
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## Licensed under the [MIT License](LICENSE)
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