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add enum concept

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This commit is contained in:
neargye 2019-11-18 13:35:59 +05:00
parent e325a70663
commit 3b2ebf7e55
2 changed files with 18 additions and 4 deletions
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10
example/example.cpp
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@ -26,6 +26,12 @@
enum class Color : int { RED = -10, BLUE = 0, GREEN = 10 };
template <typename E>
auto to_integer(magic_enum::Enum<E> value) {
// magic_enum::Enum<E> - C++17 Concept for enum type.
return static_cast<std::underlying_type_t<E>>(value);
}
int main() {
// Enum variable to string name.
Color c1 = Color::RED;
@ -44,7 +50,7 @@ int main() {
// String name to enum value.
auto c2 = magic_enum::enum_cast<Color>("BLUE");
if (c2.has_value() && c2.value() == Color::BLUE) {
std::cout << "BLUE = " << static_cast<int>(c2.value()) << std::endl; // BLUE = 0
std::cout << "BLUE = " << to_integer(c2.value()) << std::endl; // BLUE = 0
}
// Integer value to enum value.
@ -55,7 +61,7 @@ int main() {
// Enum value to integer value.
auto color_integer = magic_enum::enum_integer(Color::RED);
if (color_integer == static_cast<std::underlying_type_t<Color>>(Color::RED)) {
if (color_integer == to_integer(Color::RED)) {
std::cout << "RED = " << color_integer << std::endl; // RED = -10
}

12
include/magic_enum.hpp
View file

@ -97,7 +97,9 @@ inline constexpr bool is_enum_v = std::is_enum_v<T> && std::is_same_v<T, std::de
template <std::size_t N>
struct static_string {
constexpr static_string(std::string_view str) noexcept : static_string{str, std::make_index_sequence<N>{}} {}
constexpr static_string(std::string_view str) noexcept : static_string{str, std::make_index_sequence<N>{}} {
assert(str.size() == N);
}
constexpr const char* data() const noexcept { return chars.data(); }
@ -109,7 +111,7 @@ struct static_string {
template <std::size_t... I>
constexpr static_string(std::string_view str, std::index_sequence<I...>) noexcept : chars{{str[I]...}} {}
const std::array<char, N> chars;
const std::array<const char, N> chars;
};
template <>
@ -308,6 +310,9 @@ constexpr auto entries(std::index_sequence<I...>) noexcept {
template <typename T, typename R>
using enable_if_enum_t = std::enable_if_t<std::is_enum_v<std::decay_t<T>>, R>;
template <typename T, typename Enable = std::enable_if_t<std::is_enum_v<std::decay_t<T>>>>
using enum_concept = T;
template <typename T, bool = std::is_enum_v<T>>
struct is_scoped_enum : std::false_type {};
@ -392,6 +397,9 @@ struct enum_traits<E, std::enable_if_t<is_enum_v<E>>> {
// Checks is magic_enum supported compiler.
inline constexpr bool is_magic_enum_supported = detail::supported<void>::value;
template <typename T>
using Enum = detail::enum_concept<T>;
// Checks whether T is an Unscoped enumeration type.
// Provides the member constant value which is equal to true, if T is an [Unscoped enumeration](https://en.cppreference.com/w/cpp/language/enum#Unscoped_enumeration) type. Otherwise, value is equal to false.
template <typename T>