enum-utils (C++20)

These are a bunch of enum-related structures & utilities that I actually use regularly, these are the kind of things that are totally obvious in hindsight.

countable_enum

Countable enums are scoped enums that are contiguous from 0 and include a final value of _Count. This allows the other utilities to automatically determine their size/range.

#include <aa/enum_utils/countable.hpp>

enum class Colour
{
    Red,
    Green,
    Blue,

    _Count
};

static_assert(aa::enum_utils::is_countable_enum_v<Colour>);

aa::enum_utils::enum_count<E> will alias the std::size_t size of a countable enum.

aa::enum_utils::invalid<E> will alias _Count and is intended to be used to give flexibility to interfaces,

aa::enum_utils::valid(e) will check if a countable enum is valid.

enum_array

These are arrays that are index by a countable enum.

#include <aa/enum_utils/array.hpp>

// ...

aa::enum_utils::enum_array<Colour, int> values{};

values[Colour::Red] = 10;
values[Colour::Green] = 20;
values[Colour::Blue] = 5;

enum dictionary

Provides simple enum-string conversions, but is restricted to countable enums.

#include <aa/enum_utils/dictionary.hpp>

enum class Colour
{
    Red,
    Green,
    Blue,

    _Count
};

enum_dictionary(Colour) {
    enum_entry("Red"),
    enum_entry("Green"),
    enum_entry("Blue")
};

// ...

std::cout << aa::enum_utils::to_string(Colour::Blue);
const auto c = aa::enum_utils::parse<Color>(...);

aa::enum_utils::parse<E> is (currently) case sensitive will return aa::enum_utils::invalid<E> when not match is found.

enum_range

Exactly what you'd think

#include <aa/enum_utils/enum_range.hpp>

for (const auto c : aa::enum_utils::enum_range<Colour>())
{
    // ...
}

An enum_range for an enum_array can be accessed via .indices()

aa::enum_utils::enum_array<Colour, int> values{};

for (const Colour c:  values.indices())
{
    // ...
}

flags

Allows bitwise operators on specified enums.

#include <aa/enum_utils/flags.hpp>

enum class Options
{
    Yes = 0x1,
    No = 0x2,
    Cancel = 0x4
};

enum_flag(Options);

constexpr auto options = Options::Yes | Options::Cancel;

utility

Contains implementations of std::is_scoped_enum and std::to_underlying for those not on c++23.

variant