weekday.hpp

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// SPDX-License-Identifier: BSL-1.0
// SPDX-FileCopyrightText: Copyright (C) 2023 Tobias Hienzsch
 
#ifndef TETL_CHRONO_WEEKDAY_HPP
#define TETL_CHRONO_WEEKDAY_HPP
 
#include <etl/_chrono/duration.hpp>
#include <etl/_chrono/last_spec.hpp>
#include <etl/_chrono/local_t.hpp>
#include <etl/_chrono/system_clock.hpp>
#include <etl/_cstdint/uint_t.hpp>
 
namespace etl::chrono {
 
struct weekday_indexed;
struct weekday_last;
 
/// \ingroup chrono
struct weekday {
    weekday() = default;
 
    constexpr explicit weekday(unsigned wd) noexcept
        : _wd{static_cast<etl::uint8_t>(wd == 7 ? 0 : wd)}
    {
    }
 
    constexpr weekday(sys_days const& dp) noexcept
        : _wd{weekday_from_days(dp.time_since_epoch().count())}
    {
    }
 
    constexpr explicit weekday(local_days const& dp) noexcept
        : _wd{weekday_from_days(dp.time_since_epoch().count())}
    {
    }
 
    constexpr auto operator++() noexcept -> weekday&
    {
        return *this += etl::chrono::days{1};
    }
 
    constexpr auto operator++(int) noexcept -> weekday
    {
        return *this += etl::chrono::days{1};
    }
 
    constexpr auto operator--() noexcept -> weekday&
    {
        return *this -= etl::chrono::days{1};
    }
 
    constexpr auto operator--(int) noexcept -> weekday
    {
        return *this -= etl::chrono::days{1};
    }
 
    constexpr auto operator+=(days const& d) noexcept -> weekday&
    {
        _wd += d.count();
        _wd %= 7;
        return *this;
    }
 
    constexpr auto operator-=(days const& d) noexcept -> weekday&
    {
        _wd -= d.count();
        _wd %= 7;
        return *this;
    }
 
    [[nodiscard]] constexpr auto c_encoding() const noexcept -> unsigned
    {
        return _wd;
    }
 
    [[nodiscard]] constexpr auto iso_encoding() const noexcept -> unsigned
    {
        return _wd == 0U ? 7U : _wd;
    }
 
    [[nodiscard]] constexpr auto ok() const noexcept -> bool
    {
        return _wd < 7U;
    }
 
    // Defined in weekday_indexed
    [[nodiscard]] constexpr auto operator[](unsigned index) const noexcept -> weekday_indexed;
 
    // Defined in weekday_last
    [[nodiscard]] constexpr auto operator[](etl::chrono::last_spec /*tag*/) const noexcept -> weekday_last;
 
    friend constexpr auto operator==(weekday const& lhs, weekday const& rhs) noexcept -> bool
    {
        return lhs.c_encoding() == rhs.c_encoding();
    }
 
private:
    [[nodiscard]] static constexpr auto weekday_from_days(int tp) noexcept -> etl::uint8_t
    {
        return static_cast<etl::uint8_t>(tp >= -4 ? (tp + 4) % 7 : ((tp + 5) % 7) + 6);
    }
 
    etl::uint8_t _wd;
};
 
[[nodiscard]] constexpr auto operator+(weekday const& lhs, days const& rhs) noexcept -> weekday
{
    return weekday{static_cast<unsigned>((static_cast<int32_t>(lhs.c_encoding()) + rhs.count()) % 7)};
}
 
[[nodiscard]] constexpr auto operator+(days const& lhs, weekday const& rhs) noexcept -> weekday
{
    return rhs + lhs;
}
 
[[nodiscard]] constexpr auto operator-(weekday const& lhs, days const& rhs) noexcept -> weekday
{
    return weekday{static_cast<unsigned>((static_cast<int32_t>(lhs.c_encoding()) - rhs.count()) % 7)};
}
 
[[nodiscard]] constexpr auto operator-(weekday const& lhs, weekday const& rhs) noexcept -> days
{
    auto const count = static_cast<int_least32_t>(lhs.c_encoding() - rhs.c_encoding());
    return count >= 0 ? days{count} : days{count + 7};
}
 
// NOLINTBEGIN(readability-identifier-naming)
inline constexpr auto Sunday    = etl::chrono::weekday{0};
inline constexpr auto Monday    = etl::chrono::weekday{1};
inline constexpr auto Tuesday   = etl::chrono::weekday{2};
inline constexpr auto Wednesday = etl::chrono::weekday{3};
inline constexpr auto Thursday  = etl::chrono::weekday{4};
inline constexpr auto Friday    = etl::chrono::weekday{5};
inline constexpr auto Saturday  = etl::chrono::weekday{6};
// NOLINTEND(readability-identifier-naming)
 
} // namespace etl::chrono
 
#endif // TETL_CHRONO_WEEKDAY_HPP