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#include "base/timegm.hpp"
#include "base/assert.hpp"
#include "base/timer.hpp"
#include "std/chrono.hpp"
// There are issues with this implementation due to absence
// of time_t fromat specification. There are no guarantees
// of its internal structure so we cannot rely on + or -.
// It could be possible to substitute time_t with boost::ptime
// in contexts where we need some arithmetical and logical operations
// on time and we don't have to use precisely time_t.
namespace
{
// Number of days elapsed since Jan 01 up to each month
// (except for February in leap years).
int const g_monoff[] = {
0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334
};
int LeapDaysCount(int y1, int y2)
{
--y1;
--y2;
return (y2/4 - y1/4) - (y2/100 - y1/100) + (y2/400 - y1/400);
}
} // namespace
namespace base
{
int DaysOfMonth(int year, int month)
{
ASSERT_GREATER_OR_EQUAL(month, 1, ());
ASSERT_LESS_OR_EQUAL(month, 12, ());
int const february = base::IsLeapYear(year) ? 29 : 28;
int const daysPerMonth[12] = { 31, february, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 };
return daysPerMonth[month - 1];
}
bool IsLeapYear(int year)
{
return year % 4 == 0 && (year % 100 != 0 || year % 400 == 0);
}
// Inspired by python's calendar.py
time_t TimeGM(std::tm const & tm)
{
int year;
int days;
int hours;
int minutes;
int seconds;
year = 1900 + tm.tm_year;
days = 365 * (year - 1970) + LeapDaysCount(1970, year);
days += g_monoff[tm.tm_mon];
if (tm.tm_mon > 1 && IsLeapYear(year))
++days;
days += tm.tm_mday - 1;
hours = days * 24 + tm.tm_hour;
minutes = hours * 60 + tm.tm_min;
seconds = minutes * 60 + tm.tm_sec;
return my::SecondsSinceEpochToTimeT(seconds);
}
time_t TimeGM(int year, int month, int day, int hour, int min, int sec)
{
ASSERT_GREATER_OR_EQUAL(month, 1, ());
ASSERT_LESS_OR_EQUAL(month, 12, ());
ASSERT_GREATER_OR_EQUAL(day, 1, ());
ASSERT_LESS_OR_EQUAL(day, DaysOfMonth(year, month), ());
tm t = {};
t.tm_year = year - 1900;
t.tm_mon = month - 1;
t.tm_mday = day;
t.tm_hour = hour;
t.tm_min = min;
t.tm_sec = sec;
return TimeGM(t);
}
} // namespace base
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