ClickHouse/base/common/LocalDateTime.h

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#pragma once
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#include <string>
#include <iomanip>
#include <exception>
#include <common/DateLUT.h>
#include <common/LocalDate.h>
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/** Stores calendar date and time in broken-down form.
* Could be initialized from date and time in text form like '2011-01-01 00:00:00' or from time_t.
* Could be implicitly casted to time_t.
* NOTE: Transforming between time_t and LocalDate is done in local time zone!
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*
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* When local time was shifted backwards (due to daylight saving time or whatever reason)
* - then to resolve the ambiguity of transforming to time_t, lowest of two possible values is selected.
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*/
class LocalDateTime
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{
private:
unsigned short m_year;
unsigned char m_month;
unsigned char m_day;
unsigned char m_hour;
unsigned char m_minute;
unsigned char m_second;
/// For struct to fill 8 bytes and for safe invocation of memcmp.
/// NOTE We may use attribute packed instead, but it is less portable.
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unsigned char pad = 0;
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void init(time_t time, const DateLUTImpl & time_zone)
{
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DateLUTImpl::DateTimeComponents components = time_zone.toDateTimeComponents(time);
m_year = components.date.year;
m_month = components.date.month;
m_day = components.date.day;
m_hour = components.time.hour;
m_minute = components.time.minute;
m_second = components.time.second;
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(void)pad; /// Suppress unused private field warning.
}
void init(const char * s, size_t length)
{
if (length < 19)
throw std::runtime_error("Cannot parse LocalDateTime: " + std::string(s, length));
m_year = (s[0] - '0') * 1000 + (s[1] - '0') * 100 + (s[2] - '0') * 10 + (s[3] - '0');
m_month = (s[5] - '0') * 10 + (s[6] - '0');
m_day = (s[8] - '0') * 10 + (s[9] - '0');
m_hour = (s[11] - '0') * 10 + (s[12] - '0');
m_minute = (s[14] - '0') * 10 + (s[15] - '0');
m_second = (s[17] - '0') * 10 + (s[18] - '0');
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(void)pad;
}
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public:
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explicit LocalDateTime(time_t time, const DateLUTImpl & time_zone = DateLUT::instance())
{
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init(time, time_zone);
}
LocalDateTime(unsigned short year_, unsigned char month_, unsigned char day_,
unsigned char hour_, unsigned char minute_, unsigned char second_)
: m_year(year_), m_month(month_), m_day(day_), m_hour(hour_), m_minute(minute_), m_second(second_)
{
}
explicit LocalDateTime(const std::string & s)
{
if (s.size() < 19)
throw std::runtime_error("Cannot parse LocalDateTime: " + s);
init(s.data(), s.size());
}
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LocalDateTime() : m_year(0), m_month(0), m_day(0), m_hour(0), m_minute(0), m_second(0)
{
}
LocalDateTime(const char * data, size_t length)
{
init(data, length);
}
LocalDateTime(const LocalDateTime &) noexcept = default;
LocalDateTime & operator= (const LocalDateTime &) noexcept = default;
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unsigned short year() const { return m_year; }
unsigned char month() const { return m_month; }
unsigned char day() const { return m_day; }
unsigned char hour() const { return m_hour; }
unsigned char minute() const { return m_minute; }
unsigned char second() const { return m_second; }
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void year(unsigned short x) { m_year = x; }
void month(unsigned char x) { m_month = x; }
void day(unsigned char x) { m_day = x; }
void hour(unsigned char x) { m_hour = x; }
void minute(unsigned char x) { m_minute = x; }
void second(unsigned char x) { m_second = x; }
LocalDate toDate() const { return LocalDate(m_year, m_month, m_day); }
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LocalDateTime toStartOfDate() const { return LocalDateTime(m_year, m_month, m_day, 0, 0, 0); }
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std::string toString() const
{
std::string s{"0000-00-00 00:00:00"};
s[0] += m_year / 1000;
s[1] += (m_year / 100) % 10;
s[2] += (m_year / 10) % 10;
s[3] += m_year % 10;
s[5] += m_month / 10;
s[6] += m_month % 10;
s[8] += m_day / 10;
s[9] += m_day % 10;
s[11] += m_hour / 10;
s[12] += m_hour % 10;
s[14] += m_minute / 10;
s[15] += m_minute % 10;
s[17] += m_second / 10;
s[18] += m_second % 10;
return s;
}
bool operator< (const LocalDateTime & other) const
{
return 0 > memcmp(this, &other, sizeof(*this));
}
bool operator> (const LocalDateTime & other) const
{
return 0 < memcmp(this, &other, sizeof(*this));
}
bool operator<= (const LocalDateTime & other) const
{
return 0 >= memcmp(this, &other, sizeof(*this));
}
bool operator>= (const LocalDateTime & other) const
{
return 0 <= memcmp(this, &other, sizeof(*this));
}
bool operator== (const LocalDateTime & other) const
{
return 0 == memcmp(this, &other, sizeof(*this));
}
bool operator!= (const LocalDateTime & other) const
{
return !(*this == other);
}
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};
static_assert(sizeof(LocalDateTime) == 8);