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/*
* This source code is released into the public domain.
*/
module;
/*
* flagset: a type-type flags type.
*/
#include <concepts>
#include <cstdint>
#include <iostream>
#include <limits>
#include <print>
export module nihil.flagset;
namespace nihil {
export template<std::integral base_type, typename Tag>
struct flagset final {
using underlying_type = base_type;
/*
* Create an empty flags.
*/
flagset() noexcept = default;
/*
* Copyable.
*/
flagset(flagset const &other) noexcept
: m_value(other.m_value)
{}
/*
* Create flags from an integer mask.
*/
template<base_type flag>
[[nodiscard]] static constexpr auto mask() noexcept -> flagset
{
return flagset(flag);
}
/*
* Create flags for a specific bit.
*/
template<unsigned bitnr>
[[nodiscard]] static constexpr auto bit() noexcept -> flagset
{
static_assert(bitnr < std::numeric_limits<base_type>::digits);
return flagset(static_cast<base_type>(1) << bitnr);
}
/*
* Create flags from a runtime value.
*/
[[nodiscard]] static auto from_int(base_type value) noexcept
-> flagset
{
return flagset(value);
}
/*
* Assign this flagset.
*/
auto operator=(this flagset &lhs, flagset rhs) noexcept
-> flagset &
{
if (&lhs != &rhs)
lhs.m_value = rhs.m_value;
return lhs;
}
/*
* The integer value of this flagset.
*/
[[nodiscard]] constexpr auto value(this flagset self) noexcept
-> base_type
{
return self.m_value;
}
/*
* True if this flagset has any bits set.
*/
[[nodiscard]] explicit constexpr operator bool(this flagset self)
noexcept
{
return self.m_value != 0;
}
/*
* Set bits.
*/
constexpr auto operator|= (this flagset &lhs, flagset rhs) noexcept
-> flagset &
{
lhs.m_value |= rhs.value();
return lhs;
}
/*
* Mask bits.
*/
constexpr auto operator&= (this flagset &lhs, flagset rhs) noexcept
-> flagset &
{
lhs.m_value &= rhs.value();
return lhs;
}
/*
* Invert bits.
*/
[[nodiscard]] constexpr auto operator~ (this flagset self) noexcept
-> flagset
{
return flagset(~self.m_value);
}
/*
* xor bits.
*/
constexpr auto operator^= (this flagset &lhs, flagset rhs)
noexcept -> flagset
{
lhs.m_value ^= rhs.value();
return lhs;
}
private:
base_type m_value = 0;
explicit constexpr flagset(base_type mask) noexcept
: m_value(mask)
{}
};
export template<std::integral base_type, typename Tag>
[[nodiscard]] auto operator| (flagset<base_type, Tag> lhs,
flagset<base_type, Tag> rhs) noexcept
-> flagset<base_type, Tag>
{
return (lhs |= rhs);
}
export template<std::integral base_type, typename Tag>
[[nodiscard]] auto operator& (flagset<base_type, Tag> lhs,
flagset<base_type, Tag> rhs) noexcept
-> flagset<base_type, Tag>
{
return (lhs &= rhs);
}
export template<std::integral base_type, typename Tag>
[[nodiscard]] auto operator^ (flagset<base_type, Tag> lhs,
flagset<base_type, Tag> rhs) noexcept
-> flagset<base_type, Tag>
{
return (lhs ^= rhs);
}
export template<std::integral base_type, typename Tag>
[[nodiscard]] auto operator== (flagset<base_type, Tag> lhs,
flagset<base_type, Tag> rhs) noexcept
-> bool
{
return lhs.value() == rhs.value();
}
export template<std::integral base_type, typename Tag>
auto operator<<(std::ostream &strm, flagset<base_type, Tag> flags)
-> std::ostream &
{
std::print(strm, "{}", flags);
return strm;
}
} // namespace nihil
/*
* Formatting for flagset.
*/
export template<std::integral base_type, typename Tag, typename Char>
struct std::formatter<nihil::flagset<base_type, Tag>, Char>
{
using flags_t = nihil::flagset<base_type, Tag>;
template<typename ParseContext>
constexpr auto parse(ParseContext &ctx) -> ParseContext::iterator
{
return ctx.begin();
}
template<typename FmtContext>
auto format(flags_t flags, FmtContext& ctx) const
-> FmtContext::iterator
{
auto constexpr digits = std::numeric_limits<base_type>::digits;
auto value = flags.value();
auto it = ctx.out();
*it++ = Char{'<'};
auto printed_any = false;
for (unsigned i = 0; i < digits; ++i) {
unsigned bit = (digits - 1) - i;
auto this_bit = static_cast<base_type>(1) << bit;
if ((value & this_bit) == 0)
continue;
if (printed_any)
*it++ = Char{','};
if (bit > 10)
*it++ = Char{'0'} + (bit / 10);
*it++ = Char{'0'} + (bit % 10);
printed_any = true;
}
*it++ = Char{'>'};
return it;
}
};
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