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113 lines
3.9 KiB
C++
113 lines
3.9 KiB
C++
#include <civil_time.h>
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#include <time_zone.h>
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#include <common/DateLUTImpl.h>
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#include <Poco/Exception.h>
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#include <memory>
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#include <chrono>
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#include <cstring>
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#include <iostream>
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namespace
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{
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UInt8 getDayOfWeek(const cctz::civil_day & date)
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{
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cctz::weekday day_of_week = cctz::get_weekday(date);
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switch (day_of_week)
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{
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case cctz::weekday::monday: return 1;
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case cctz::weekday::tuesday: return 2;
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case cctz::weekday::wednesday: return 3;
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case cctz::weekday::thursday: return 4;
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case cctz::weekday::friday: return 5;
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case cctz::weekday::saturday: return 6;
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case cctz::weekday::sunday: return 7;
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default:
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throw Poco::Exception("Logical error: incorrect week day.");
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}
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}
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}
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DateLUTImpl::DateLUTImpl(const std::string & time_zone_)
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: time_zone(time_zone_)
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{
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size_t i = 0;
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time_t start_of_day = DATE_LUT_MIN;
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cctz::time_zone cctz_time_zone;
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if (!cctz::load_time_zone(time_zone.data(), &cctz_time_zone))
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throw Poco::Exception("Cannot load time zone " + time_zone_);
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cctz::time_zone::absolute_lookup start_of_epoch_lookup = cctz_time_zone.lookup(std::chrono::system_clock::from_time_t(start_of_day));
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offset_at_start_of_epoch = start_of_epoch_lookup.offset;
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cctz::civil_day date{1970, 1, 1};
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do
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{
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cctz::time_zone::civil_lookup lookup = cctz_time_zone.lookup(date);
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start_of_day = std::chrono::system_clock::to_time_t(lookup.pre); /// Ambiguouty is possible.
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Values & values = lut[i];
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values.year = date.year();
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values.month = date.month();
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values.day_of_month = date.day();
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values.day_of_week = getDayOfWeek(date);
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values.date = start_of_day;
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values.time_at_offset_change = 0;
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values.amount_of_offset_change = 0;
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/// If UTC offset was changed in previous day.
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if (i != 0)
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{
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auto amount_of_offset_change_at_prev_day = 86400 - (lut[i].date - lut[i - 1].date);
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if (amount_of_offset_change_at_prev_day)
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{
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lut[i - 1].amount_of_offset_change = amount_of_offset_change_at_prev_day;
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const auto utc_offset_at_beginning_of_day = cctz_time_zone.lookup(std::chrono::system_clock::from_time_t(lut[i - 1].date)).offset;
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/// Find a time (timestamp offset from beginning of day),
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/// when UTC offset was changed. Search is performed with 15-minute granularity, assuming it is enough.
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time_t time_at_offset_change = 900;
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while (time_at_offset_change < 65536)
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{
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auto utc_offset_at_current_time = cctz_time_zone.lookup(std::chrono::system_clock::from_time_t(
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lut[i - 1].date + time_at_offset_change)).offset;
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if (utc_offset_at_current_time != utc_offset_at_beginning_of_day)
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break;
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time_at_offset_change += 900;
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}
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lut[i - 1].time_at_offset_change = time_at_offset_change >= 65536 ? 0 : time_at_offset_change;
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/* std::cerr << lut[i - 1].year << "-" << int(lut[i - 1].month) << "-" << int(lut[i - 1].day_of_month)
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<< " offset was changed at " << lut[i - 1].time_at_offset_change << " for " << lut[i - 1].amount_of_offset_change << " seconds.\n";*/
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}
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}
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/// Going to next day.
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++date;
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++i;
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}
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while (start_of_day <= DATE_LUT_MAX && i <= DATE_LUT_MAX_DAY_NUM);
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/// Заполняем lookup таблицу для годов
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::memset(years_lut, 0, DATE_LUT_YEARS * sizeof(years_lut[0]));
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for (size_t day = 0; day < i && lut[day].year <= DATE_LUT_MAX_YEAR; ++day)
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{
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if (lut[day].month == 1 && lut[day].day_of_month == 1)
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years_lut[lut[day].year - DATE_LUT_MIN_YEAR] = day;
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}
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}
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