简易实现枚举类型到字符串

#include <array>
#include <string>
#include <utility>
#include <string_view>template <typename E, E V>
constexpr auto PrettyName()
{std::string_view name{__PRETTY_FUNCTION__, sizeof(__PRETTY_FUNCTION__) - 2};name.remove_prefix(name.find_last_of(" ") + 1);if (name.front() == '(') name.remove_prefix(name.size());return name;
}template <typename E, E V>
constexpr bool IsValidEnum()
{return !PrettyName<E, V>().empty();
}template <int... Seq>
constexpr auto MakeIntegerSequence(std::integer_sequence<int, Seq...>)
{return std::integer_sequence<int, (Seq)...>();
}constexpr auto NormalIntegerSequence = MakeIntegerSequence(std::make_integer_sequence<int, 32>());template <typename E, int... Seq>
constexpr size_t GetEnumSize(std::integer_sequence<int, Seq...>)
{constexpr std::array<bool, sizeof...(Seq)> valid{IsValidEnum<E, static_cast<E>(Seq)>()...};constexpr std::size_t count = [](decltype((valid)) v) constexpr noexcept->std::size_t{auto cnt = std::size_t{0};for (auto b : v) if (b) ++cnt;return cnt;}(valid);return count;
}template <typename E, int... Seq>
constexpr auto GetAllValidValues(std::integer_sequence<int, Seq...>)
{constexpr std::size_t count = sizeof...(Seq);constexpr std::array<bool, count> valid{IsValidEnum<E, static_cast<E>(Seq)>()...};constexpr std::array<int, count> seq{Seq...};std::array<int, GetEnumSize<E>(NormalIntegerSequence)> values{};for (std::size_t i = 0, v = 0; i < count; ++i) if (valid[i]) values[v++] = seq[i];return values;
}template <typename E, int... Seq>
constexpr auto GetAllValidNames(std::integer_sequence<int, Seq...>)
{constexpr std::array<std::string_view, sizeof...(Seq)> names{PrettyName<E, static_cast<E>(Seq)>()...};std::array<std::string_view, GetEnumSize<E>(NormalIntegerSequence)> validNames{};for (std::size_t i = 0, v = 0; i < names.size(); ++i) if (!names[i].empty()) validNames[v++] = names[i];return validNames;
}template <typename E>
constexpr std::string_view Enum2String(E V)
{constexpr auto names = GetAllValidNames<E>(NormalIntegerSequence);constexpr auto values = GetAllValidValues<E>(NormalIntegerSequence);constexpr auto size = GetEnumSize<E>(NormalIntegerSequence);for (size_t i = 0; i < size; ++i) if (static_cast<int>(V) == values[i]) return names[i];return std::to_string(static_cast<int>(V));
}