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Make enum_fuse typesafe (fixes #143) (#145)

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Pavel I. Kryukov 2022-03-08 11:38:19 +03:00 • committed by GitHub
parent 785b3f253d
commit 9d1cf196cf
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3 changed files with 34 additions and 7 deletions
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@ -330,10 +330,16 @@ constexpr string_view enum_type_name() noexcept;
```cpp
template <typename... Es>
[[nodiscard]] constexpr optional<std::uintmax_t> enum_fuse(Es... values);
[[nodiscard]] constexpr optional<FusedEnum> enum_fuse(Es... values);
```
* Returns a bijective mix of several enum values. This can be used to emulate 2D switch/case statements.
* Returns a typesafe bijective mix of several enum values. This can be used to emulate 2D switch/case statements.
* Return type is `optional<FusedEnum>` where FusedEnum is an incomplete enum. It is unique for any given combination of `Es...`.
* Switch/case statement over an incomplete enum is a Visual Studio warning C4064
* You have to silent (/wd4064) or ignore it.
* Alternatively, define MAGIC_ENUM_NO_TYPESAFE_ENUM_FUSE to disable type-safety (FusedEnum equals std::uintmax_t).
* Examples
@ -341,6 +347,7 @@ template <typename... Es>
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(): // ...
case magic_enum::enum_fuse(Directions::BLUE, Color::Down).value(): // Compilation error
// ...
}
```