chrono.hpp

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/*
    Copyright (C) 2024
    Part of the Battle for Wesnoth Project https://www.wesnoth.org/
 
    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 2 of the License, or
    (at your option) any later version.
    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY.
 
    See the COPYING file for more details.
*/
 
#pragma once
 
#include "config_attribute_value.hpp"
 
#include <chrono>
#include <iomanip>
#include <sstream>
#include <string_view>
 
#if __cpp_lib_chrono >= 201907L
#define CPP20_CHRONO_SUPPORT
#endif
 
namespace chrono
{
#ifdef CPP20_CHRONO_SUPPORT
 
using std::chrono::days;
using std::chrono::weeks;
using std::chrono::months;
using std::chrono::years;
 
#else
 
using days   = std::chrono::duration<int, std::ratio<86400>>;
using weeks  = std::chrono::duration<int, std::ratio<604800>>;
using months = std::chrono::duration<int, std::ratio<2629746>>;
using years  = std::chrono::duration<int, std::ratio<31556952>>;
 
#endif
 
inline auto parse_timestamp(long long val)
{
    return std::chrono::system_clock::from_time_t(val);
}
 
inline auto parse_timestamp(const config_attribute_value& val)
{
    return std::chrono::system_clock::from_time_t(val.to_long_long());
}
 
inline auto serialize_timestamp(const std::chrono::system_clock::time_point& time)
{
    return std::chrono::system_clock::to_time_t(time);
}
 
inline auto format_local_timestamp(const std::chrono::system_clock::time_point& time, std::string_view format = "%F %T")
{
    std::ostringstream ss;
    auto as_time_t = std::chrono::system_clock::to_time_t(time);
    ss << std::put_time(std::localtime(&as_time_t), format.data());
    return ss.str();
}
 
template<typename Duration>
inline auto parse_duration(const config_attribute_value& val, const Duration& def = Duration{0})
{
    return Duration{val.to_long_long(def.count())};
}
 
template<typename... Ts, typename Rep, typename Period>
constexpr auto deconstruct_duration(const std::tuple<Ts...>&, const std::chrono::duration<Rep, Period>& span)
{
    auto time_remaining = std::chrono::duration_cast<std::common_type_t<Ts...>>(span);
    return std::tuple{[&time_remaining]() {
        auto duration = std::chrono::duration_cast<Ts>(time_remaining);
        time_remaining -= duration;
        return duration;
    }()...};
}
 
/** Helper types to be used with @ref deconstruct_duration */
namespace format
{
constexpr auto days_hours_mins_secs = std::tuple<
    chrono::days,
    std::chrono::hours,
    std::chrono::minutes,
    std::chrono::seconds
>{};
 
} // namespace format
 
} // namespace chrono