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clean-up

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neargye 2022-02-10 20:17:44 +02:00
parent 1f8e29b140
commit 63ff515163
4 changed files with 43 additions and 41 deletions
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6
README.md
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@ -141,9 +141,9 @@ enum class Color { RED = 2, BLUE = 4, GREEN = 8 };
* Enum fusion for multi-level switch/case statements * Enum fusion for multi-level switch/case statements
```cpp ```cpp
switch (magic_enum::enum_fuse(color1, color2)) { switch (magic_enum::enum_fuse(color, direction)) {
case magic_enum::enum_fuse(RED, BLUE): // ... case magic_enum::enum_fuse(Color::RED, Directions::Up): // ...
case magic_enum::enum_fuse(RED, RED): // ... case magic_enum::enum_fuse(Color::BLUE, Directions::Down): // ...
// ... // ...
} }
``` ```

10
doc/reference.md
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@ -329,8 +329,8 @@ constexpr string_view enum_type_name() noexcept;
## `enum_fuse` ## `enum_fuse`
```cpp ```cpp
template<typename ... Es> template <typename... Es>
[[nodiscard]] constexpr size_t enum_fuse(Es ... values); [[nodiscard]] constexpr std::size_t enum_fuse(Es... values);
``` ```
* Returns a bijective mix of several enum values with [Cantor pairing function](https://en.wikipedia.org/wiki/Pairing_function). This can be used to emulate 2D switch/case statements. * Returns a bijective mix of several enum values with [Cantor pairing function](https://en.wikipedia.org/wiki/Pairing_function). This can be used to emulate 2D switch/case statements.
@ -338,9 +338,9 @@ template<typename ... Es>
* Examples * Examples
```cpp ```cpp
switch (magic_enum::enum_fuse(color1, color2)) { switch (magic_enum::enum_fuse(color, direction)) {
case magic_enum::enum_fuse(RED, BLUE): // ... case magic_enum::enum_fuse(Color::RED, Directions::Up): // ...
case magic_enum::enum_fuse(RED, RED): // ... case magic_enum::enum_fuse(Color::BLUE, Directions::Down): // ...
// ... // ...
} }
``` ```

30
include/magic_enum.hpp
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@ -324,6 +324,15 @@ constexpr I log2(I value) noexcept {
return ret; return ret;
} }
constexpr std::size_t cantor_pair(size_t v1, size_t v2) noexcept {
return (((v1 + v2) * (v1 + v2 + 1)) >> 1) + v2;
}
template <typename... Ts>
constexpr std::size_t cantor_pair(std::size_t v1, std::size_t head, Ts... tail) noexcept {
return cantor_pair(cantor_pair(v1, head), tail...);
}
template <typename T> template <typename T>
inline constexpr bool is_enum_v = std::is_enum_v<T> && std::is_same_v<T, std::decay_t<T>>; inline constexpr bool is_enum_v = std::is_enum_v<T> && std::is_same_v<T, std::decay_t<T>>;
@ -609,15 +618,6 @@ struct underlying_type {};
template <typename T> template <typename T>
struct underlying_type<T, true> : std::underlying_type<std::decay_t<T>> {}; struct underlying_type<T, true> : std::underlying_type<std::decay_t<T>> {};
constexpr size_t cantor_pair(size_t v1, size_t v2) noexcept {
return (((v1 + v2) * (v1 + v2 + 1)) >> 1) + v2;
}
template<typename ... Ts>
constexpr size_t cantor_pair(size_t v1, size_t head, Ts ... tail) noexcept {
return cantor_pair(cantor_pair(v1, head), tail...);
}
} // namespace magic_enum::detail } // namespace magic_enum::detail
// Checks is magic_enum supported compiler. // Checks is magic_enum supported compiler.
@ -887,11 +887,17 @@ template <typename E>
return {}; // Invalid value or out of range. return {}; // Invalid value or out of range.
} }
template<typename ... Es> // Returns a bijective mix of several enum values with [Cantor pairing function](https://en.wikipedia.org/wiki/Pairing_function). This can be used to emulate 2D switch/case statements.
[[nodiscard]] constexpr size_t enum_fuse(Es ... enums) { template <typename... Es>
[[nodiscard]] constexpr auto enum_fuse(Es... values) -> std::enable_if_t<(std::is_enum_v<std::decay_t<Es>> && ...), std::size_t>{
static_assert(sizeof...(Es) >= 2, "magic_enum::enum_fuse requires at least 2 enums"); static_assert(sizeof...(Es) >= 2, "magic_enum::enum_fuse requires at least 2 enums");
#ifdef __cpp_lib_is_constant_evaluated
if (std::is_constant_evaluated() && !(enum_index(values).has_value() && ...)) {
throw std::logic_error("magic_enum::enum_fuse accepts only in-range enum values");
}
#endif
// Add 1 to prevent matching 2D fusions with 3D fusions etc. // Add 1 to prevent matching 2D fusions with 3D fusions etc.
return detail::cantor_pair((enum_index(enums).value() + 1)...); return assert((enum_index(values).has_value() && ...)), detail::cantor_pair((enum_index(values).value() + 1)...);
} }
// Checks whether enum contains enumerator with such enum value. // Checks whether enum contains enumerator with such enum value.

38
test/test.cpp
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@ -1014,32 +1014,28 @@ TEST_CASE("constexpr_for") {
}); });
} }
static int switch_case_2d(Color color, Directions number) static int switch_case_2d(Color color, Directions direction) {
{ switch (magic_enum::enum_fuse(color, direction)) {
switch (magic_enum::enum_fuse(color, number)) case magic_enum::enum_fuse(Color::RED, Directions::Up):
{ return 1;
case magic_enum::enum_fuse(Color::RED, Directions::Up): case magic_enum::enum_fuse(Color::BLUE, Directions::Down):
return 1; return 2;
case magic_enum::enum_fuse(Color::BLUE, Directions::Down): default:
return 2; return 0;
default:
return 0;
} }
} }
enum class Index { zero = 0, one = 1, two = 2 }; enum class Index { zero = 0, one = 1, two = 2 };
static int switch_case_3d(Color color, Directions number, Index index) static int switch_case_3d(Color color, Directions direction, Index index) {
{ switch (magic_enum::enum_fuse(color, direction, index)) {
switch (magic_enum::enum_fuse(color, number, index)) case magic_enum::enum_fuse(Color::RED, Directions::Up, Index::zero):
{ return 1;
case magic_enum::enum_fuse(Color::RED, Directions::Up, Index::zero): // model accidental removal of last index, must not match anything
return 1; case magic_enum::enum_fuse(Color::BLUE, Directions::Up):
// model accidental removal of last index, must not match anything return 2;
case magic_enum::enum_fuse(Color::BLUE, Directions::Up): default:
return 2; return 0;
default:
return 0;
} }
} }