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// This source code is released into the public domain.
export module nihil.util:flagset;
/*
* flagset: a type-safe flags type.
*/
import nihil.std;
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)
{
}
[[nodiscard]] friend auto operator|(flagset lhs, flagset rhs) noexcept -> flagset
{
return (lhs |= rhs);
}
[[nodiscard]] friend auto operator&(flagset lhs, flagset rhs) noexcept -> flagset
{
return (lhs &= rhs);
}
[[nodiscard]] friend auto operator^(flagset lhs, flagset rhs) noexcept -> flagset
{
return (lhs ^= rhs);
}
[[nodiscard]] friend auto
operator==(flagset lhs, flagset rhs) noexcept -> bool
{
return lhs.value() == rhs.value();
}
friend 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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