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enum_set.hpp
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enum_set.hpp
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#ifndef ENUM_SET_ENUM_SET_HPP
#define ENUM_SET_ENUM_SET_HPP
#include <enum_set/integer_set.hpp>
#include <enum_set/standard_types.hpp>
#include <type_traits>
#include <utility>
namespace enum_set
{
namespace detail
{
/// Representation of a sequence of `Values...` of a certain `Type`.
/// Used because `std::integer_sequence` does not work with enums on all platforms.
template <typename Type, Type... Values>
struct value_sequence
{
};
/// Factory for `make_enum_sequence` meta function below.
/// `Enum` must be of enumeration type.
/// `Last` must be the last value of the `Enum` type.
template <typename Enum, Enum Last>
struct enum_sequence_factory
{
static_assert(std::is_enum<Enum>::value,
"enum_sequence_factory can only be instantiated with an enumeration type");
using arithmetic_value_type = std::underlying_type_t<Enum>;
using make_arithmetic_sequence =
std::make_integer_sequence<
arithmetic_value_type,
static_cast<arithmetic_value_type>(Last) + 1
>;
template <arithmetic_value_type... Values>
static value_sequence<Enum, static_cast<Enum>(Values)...>
make_type(std::integer_sequence<arithmetic_value_type, Values...>);
using type = decltype(make_type(make_arithmetic_sequence()));
};
/// Creates a sequence of values of an `Enum` type ranging from 0 to (including) `Last`.
template <typename Enum, Enum Last>
using make_enum_sequence = typename enum_sequence_factory<Enum, Last>::type;
} // namespace detail
/// Factory for building a `value_set` for an enumeration type `Enum`, terminated by `Last` value.
/// The enumerations of the `Enum = enum [class] { E_0, E_1, ..., E_N }` is assumed to have default
/// values so that the values of the underlying type is `{ 0, 1, ..., N }`.
/// Performs the map
///
/// [Enum, Last] -> value_set<Enum, E_0, E_1, ..., E_N>
///
/// `Enum` must be of enumeration type.
/// `Last` must be the last enumeration in the `Enum`.
template <typename Enum, Enum Last>
struct enum_set_factory
{
template <Enum... Values>
static value_set<Enum, Values...>
make_type(detail::value_sequence<Enum, Values...>);
using type = decltype(make_type(detail::make_enum_sequence<Enum, Last>()));
};
/// Creates a `value_set` for an enumeration type `Enum`, terminated by `Last` value.
/// See `enum_set_factory` for details.
template <typename Enum, Enum Last>
using make_enum_set = typename enum_set_factory<Enum, Last>::type;
} // namespace enum_set
#endif // ENUM_SET_ENUM_SET_HPP