date_conversions.hpp

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// SPDX-License-Identifier: MIT
#pragma once
#ifndef TIME_SHIELD_HEADER_CONVERSIONS_DATE_CONVERSIONS_HPP_INCLUDED
#define TIME_SHIELD_HEADER_CONVERSIONS_DATE_CONVERSIONS_HPP_INCLUDED
 
 
#include <time_shield/core.hpp>
#include "unix_time_conversions.hpp"
 
namespace time_shield {
 
 
    template<class T = year_t>
    TIME_SHIELD_CONSTEXPR inline T year_of(ts_t ts = time_shield::ts()) {
        return years_since_epoch<T>(ts) + static_cast<T>(UNIX_EPOCH);
    }
 
    template<class T = year_t>
    TIME_SHIELD_CONSTEXPR inline T year_of_ms(ts_ms_t ts_ms = time_shield::ts_ms()) {
        return year_of<T>(ms_to_sec<ts_t>(ts_ms));
    }
 
    template<class T1 = int, class T2 = year_t>
    TIME_SHIELD_CONSTEXPR inline T1 num_days_in_year(T2 year) noexcept {
        if (is_leap_year_date(year)) return DAYS_PER_LEAP_YEAR;
        return DAYS_PER_YEAR;
    }
 
    template<class T = int>
    TIME_SHIELD_CONSTEXPR inline T num_days_in_year_ts(ts_t ts = time_shield::ts()) {
        if (is_leap_year_ts(ts)) return DAYS_PER_LEAP_YEAR;
        return DAYS_PER_YEAR;
    }
 
    template<class T1 = Weekday, class T2 = year_t, class T3 = int, class T4 = int>
    TIME_SHIELD_CONSTEXPR inline T1 day_of_week_date(T2 year, T3 month, T4 day) {
        year_t a = 0;
        year_t y = 0;
        year_t m = 0;
        year_t R = 0;
        a = (14 - month) / MONTHS_PER_YEAR;
        y = year - a;
        m = month + MONTHS_PER_YEAR * a - 2;
        R = 7000 + ( day + y + (y / 4) - (y / 100) + (y / 400) + (31 * m) / MONTHS_PER_YEAR);
        return static_cast<T1>(R % DAYS_PER_WEEK);
    }
 
    template<class T1 = Weekday, class T2>
    TIME_SHIELD_CONSTEXPR inline T1 weekday_of_date(const T2& date) {
        return day_of_week_date(date.year, date.mon, date.day);
    }
 
    template<class T1 = Weekday, class T2>
    TIME_SHIELD_CONSTEXPR inline T1 weekday_from_date(const T2& date) {
        return weekday_of_date<T1>(date);
    }
 
 
}; // namespace time_shield
 
#endif // TIME_SHIELD_HEADER_CONVERSIONS_DATE_CONVERSIONS_HPP_INCLUDED