105 lines
3.5 KiB
C++
105 lines
3.5 KiB
C++
//
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// Copyright (c) 2019-2024 Ruben Perez Hidalgo (rubenperez038 at gmail dot com)
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//
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// Distributed under the Boost Software License, Version 1.0. (See accompanying
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// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
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//
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#ifndef BOOST_MYSQL_DETAIL_DATETIME_HPP
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#define BOOST_MYSQL_DETAIL_DATETIME_HPP
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// All these algorithms have been taken from:
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// http://howardhinnant.github.io/date_algorithms.html
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#include <boost/assert.hpp>
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#include <boost/config.hpp>
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#include <cstdint>
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#include <limits>
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namespace boost {
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namespace mysql {
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namespace detail {
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// Helpers
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BOOST_INLINE_CONSTEXPR unsigned char last_month_day_arr[] = {31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
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constexpr bool is_leap(std::uint16_t y) noexcept { return y % 4 == 0 && (y % 100 != 0 || y % 400 == 0); }
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constexpr inline std::uint8_t last_month_day(std::uint16_t y, std::uint8_t m) noexcept
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{
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return m != 2 || !is_leap(y) ? last_month_day_arr[m - 1] : 29u;
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}
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// Interface
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BOOST_INLINE_CONSTEXPR std::uint16_t max_year = 9999;
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BOOST_INLINE_CONSTEXPR std::uint8_t max_month = 12;
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BOOST_INLINE_CONSTEXPR std::uint8_t max_day = 31;
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BOOST_INLINE_CONSTEXPR std::uint8_t max_hour = 23;
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BOOST_INLINE_CONSTEXPR std::uint8_t max_min = 59;
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BOOST_INLINE_CONSTEXPR std::uint8_t max_sec = 59;
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BOOST_INLINE_CONSTEXPR std::uint32_t max_micro = 999999;
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constexpr inline bool is_valid(std::uint16_t years, std::uint8_t month, std::uint8_t day) noexcept
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{
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return years <= max_year && month > 0 && month <= max_month && day > 0 &&
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day <= last_month_day(years, month);
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}
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BOOST_CXX14_CONSTEXPR inline int ymd_to_days(
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std::uint16_t years,
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std::uint8_t month,
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std::uint8_t day
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) noexcept
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{
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BOOST_ASSERT(is_valid(years, month, day));
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int y = years;
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const int m = month;
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const int d = day;
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y -= m <= 2;
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const int era = (y >= 0 ? y : y - 399) / 400;
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const unsigned yoe = static_cast<unsigned>(y - era * 400); // [0, 399]
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const unsigned doy = (153 * (m + (m > 2 ? -3 : 9)) + 2) / 5 + d - 1; // [0, 365]
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const unsigned doe = yoe * 365 + yoe / 4 - yoe / 100 + doy; // [0, 146096]
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return era * 146097 + static_cast<int>(doe) - 719468;
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}
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BOOST_CXX14_CONSTEXPR inline bool days_to_ymd(
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int num_days,
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std::uint16_t& years,
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std::uint8_t& month,
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std::uint8_t& day
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) noexcept
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{
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// Prevent overflow
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constexpr int days_magic = 719468;
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if (num_days > (std::numeric_limits<int>::max)() - days_magic)
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return false;
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num_days += days_magic;
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const int era = (num_days >= 0 ? num_days : num_days - 146096) / 146097;
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const unsigned doe = static_cast<unsigned>(num_days - era * 146097); // [0, 146096]
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const unsigned yoe = (doe - doe / 1460 + doe / 36524 - doe / 146096) / 365; // [0, 399]
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const int y = static_cast<int>(yoe) + era * 400;
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const unsigned doy = doe - (365 * yoe + yoe / 4 - yoe / 100); // [0, 365]
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const unsigned mp = (5 * doy + 2) / 153; // [0, 11]
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const unsigned d = doy - (153 * mp + 2) / 5 + 1; // [1, 31]
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const unsigned m = mp + (mp < 10 ? 3 : -9); // [1, 12]
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const int final_year = y + (m <= 2);
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if (final_year < 0 || final_year > static_cast<int>(max_year))
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return false;
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else
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{
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years = static_cast<std::uint16_t>(final_year);
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month = static_cast<std::uint8_t>(m);
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day = static_cast<std::uint8_t>(d);
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return true;
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}
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}
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} // namespace detail
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} // namespace mysql
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} // namespace boost
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#endif
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