lgraph_date_time

Implemnets the DateTime, Date and TimeZone classes.

namespace lgraph_api

Functions

static inline constexpr int32_t MinDaysSinceEpochForDate(): min and max values that Date can hold

static inline constexpr int32_t MaxDaysSinceEpochForDate(): Maximum days since epoch for date.

static inline constexpr int64_t MinMicroSecondsSinceEpochForDateTime(): min and max values that Date can hold

static inline constexpr int64_t MaxMicroSecondsSinceEpochForDateTime(): Maximum microseconds since epoch for date time.

class Date

#include <lgraph_date_time.h>

Implements the Date class. Range of dates is from 0/1/1 to 12/31/9999.

Public Functions

Date(): Construct a new Date object with the date set to 1970/1/1.

explicit Date(const std::chrono::system_clock::time_point &tp)

Construct a new Date object with date set to the specified time. The time point must be in the range of 0/1/1 to 12/31/9999.

Throws: OutOfRangeError – Thrown if the time point is out of range.
Parameters: tp – Time point to set the date to.

explicit Date(const YearMonthDay &ymd)

Construct a new Date object with date set to the specified date. The date must be in the range of 0/1/1 to 12/31/9999.

Throws: OutOfRangeError – Thrown if the time point is out of range.
Parameters: ymd – Date in the form of year, month and day.

explicit Date(int32_t days_since_epoch)

Construct a new Date object with date set to an offset from epoch, i.e. the date is set to the specified number of days from epoch. The result date must be in the range of 0/1/1 to 12/31/9999.

Throws: OutOfRangeError – Thrown if the time point is out of range.
Parameters: days_since_epoch – Number of days since epoch.

explicit Date(const std::string &str)

Parse date from a YYYY-MM-DD string.

Throws: InputError – if the string is not in the correct format.
Parameters: str – The string.

YearMonthDay GetYearMonthDay() const noexcept

Returns the current Date in the form of year, month and day.

Returns: The year month day.

Date operator+(int days) const

Add a number of days to the Date object.

Throws: OutOfRangeError – Thrown if the time point is out of range.
Parameters: days – Number of days to add.
Returns: The resulting Date object.

Date &operator+=(int days)

Add a number of days to the current Date object. In case of overflow, current object is not modified.

Throws: OutOfRangeError – Thrown if the resulting date is out of range.
Parameters: days – Number of days to add.
Returns: Reference to the current date.

Date operator-(int days) const

Subtract a number of days from the Date object.

Throws: OutOfRangeError – Thrown if the resulting date is out of range.
Parameters: days – Number of days to subtract.
Returns: The resulting Date object.

Date &operator-=(int days)

Subtract a number of days from the current Date object. In case of overflow, current object is not modified.

Throws: OutOfRangeError – Thrown if the resulting date is out of range.
Parameters: days – Number of days to subtract.
Returns: Reference to the current Date object.

bool operator<(const Date &rhs) const noexcept

bool operator<=(const Date &rhs) const noexcept

bool operator>(const Date &rhs) const noexcept

bool operator>=(const Date &rhs) const noexcept

bool operator==(const Date &rhs) const noexcept

bool operator!=(const Date &rhs) const noexcept

int32_t DaysSinceEpoch() const noexcept: Returns the number of days this date is since epoch.

int32_t GetStorage() const noexcept: Returns the number of days this date is since epoch.

explicit operator int32_t() const noexcept: Returns the number of days this date is since epoch.

std::chrono::system_clock::time_point TimePoint() const noexcept: Returns the timepoint corresponding to this date at 00:00 am.

std::string ToString() const noexcept: Get the string representation of the date in the format of YYYY-MM-DD.

explicit operator DateTime() const noexcept: Get the DateTime object corresponding to 00:00 am on this date.

Public Static Functions

static bool Parse(const std::string &str, Date &d) noexcept

Parse date from YYYY-MM-DD, save value in d.

Parameters

str – The string.
d – [out] The resulting Date.

Returns

True if success, otherwise false.

static size_t Parse(const char *beg, const char *end, Date &d) noexcept

Parse date from YYYY-MM-DD, save value in d.

Parameters

beg – The beg.
end – The end.
d – [out] The result.

Returns

Number of bytes parsed (must be 10), 0 if failed.

static Date Now() noexcept

Returns the current Date.

Returns: Current Date in UTC.

static Date LocalNow() noexcept

Returns the current Date in local timezone.

Returns: Current Date in local timezone.

Private Members

int32_t days_since_epoch_: The days since epoch.

struct YearMonthDay

#include <lgraph_date_time.h>

Structure representing a date in the format of year, month and day.

Public Members

int year: The year, 0-9999.

unsigned month: Month, 1-12.

unsigned day: Day, 1-31.

class DateTime

#include <lgraph_date_time.h>

Implements a DateTime class that holds DateTime in the range of 0000-01-01 00:00:00.000000 to 9999-12-31 23:59:59.999999.

Public Functions

DateTime(): Construct a new DateTime object with date set to the epoch time, i.e., 1970-1-1 00:00:00.

explicit DateTime(const std::chrono::system_clock::time_point &tp)

Construct a new DateTime object with date set to the specified timepoint.

Throws: OutOfRangeError – Thrown if the time point is out of range.
Parameters: tp – Timepoint to set the DateTime to.

explicit DateTime(const YMDHMSF &ymdhmsf)

Construct a new DateTime object with date set to the specified date and time given in YMDHMSF.

Throws: OutOfRangeError – Thrown if the time point is out of range.
Parameters: ymdhmsf – Date and time to set the DateTime to.

explicit DateTime(int64_t microseconds_since_epoch)

Construct a new DateTime object with date set to specified number of microseconds since epoch.

Throws: OutOfRangeError – Thrown if the time point is out of range.
Parameters: microseconds_since_epoch – Number of microseconds since epoch.

explicit DateTime(const std::string &str)

Construct a new DateTime object with date set to the specified date and time given in the form of YYYY-MM-DD HH:MM:SS[.FFFFFF].

Throws

OutOfRangeError – Thrown if the time point is out of range.
InputError – Thrown if str has invalid format.

Parameters

str – String representation of the date and time in the form of YYYY-MM-DD HH:MM:SS.

YMDHMSF GetYMDHMSF() const noexcept

Get current DateTime in the form of year, month, day, hour, minute, second, fraction.

Returns: The ymdhmsf.

DateTime operator+(int64_t n_microseconds) const

Add a number of microseconds to the DateTime.

Throws: OutOfRangeError – Thrown if the resulting DateTime is out of range.
Parameters: n_microseconds – Number of micorseconds to add.
Returns: The resulting DateTime.

DateTime &operator+=(int64_t n_microseconds)

Adds a number of microseconds to the current DateTime object. In case of overflow, the current DateTime object is not modified.

Throws: OutOfRangeError – Thrown if the resulting DateTime is out of range.
Parameters: n_microseconds – Number of microseconds to add.
Returns: A reference to current object.

DateTime operator-(int64_t n_microseconds) const

Subtract a number of microseconds from the DateTime.

Throws: OutOfRangeError – Thrown if the resulting DateTime is out of range.
Parameters: n_microseconds – Number of microseconds to subtract.
Returns: The resulting DateTime.

DateTime &operator-=(int64_t n_microseconds)

Subtract a number of microseconds from the current DateTime object. In case of overflow, the current DateTime object is not modified.

Throws: OutOfRangeError – Thrown if the resulting DateTime is out of range.
Parameters: n_microseconds – Number of microseconds to subtract.
Returns: A reference to current object.

bool operator<(const DateTime &rhs) const noexcept

bool operator<=(const DateTime &rhs) const noexcept

bool operator>(const DateTime &rhs) const noexcept

bool operator>=(const DateTime &rhs) const noexcept

bool operator==(const DateTime &rhs) const noexcept

bool operator!=(const DateTime &rhs) const noexcept

int64_t MicroSecondsSinceEpoch() const noexcept: Get the number of microseconds this DateTime is since epoch.

int64_t GetStorage() const noexcept: Get the number of microseconds this DateTime is since epoch.

explicit operator int64_t() const noexcept: Get the number of microseconds this DateTime is since epoch.

std::chrono::system_clock::time_point TimePoint() const noexcept: Get the timepoint correponding to this DateTime.

std::string ToString() const noexcept: Get string representation of the date and time in the form of YYYY-MM-DD HH:MM:SS.[ffffff].

explicit operator Date() const noexcept: Get the Date object corresponding to this DateTime.

DateTime ConvertToUTC()

Get the UTC time corresponding to this DateTime, assuming current DateTime is a local time.

Throws: OutOfRangeError – Thrown if the resulting DateTime is out of range.
Returns: Object converted to an UTC.

DateTime ConvertToLocal()

Get the local time corresponding to this DateTime, assuming current DateTime is a UTC time.

Throws: OutOfRangeError – Thrown if the resulting DateTime is out of range.
Returns: Object converted to a local.

Public Static Functions

static bool Parse(const std::string &str, DateTime &d) noexcept

Parse date from YYYY-MM-DD HH:MM:SS(.FFFFFF), save value in d.

Parameters

str – The string.
d – [out] A DateTime to process.

Returns

True if success, otherwise false.

static size_t Parse(const char *beg, const char *end, DateTime &d) noexcept

Parse date from YYYY-MM-DD HH:MM:SS(.FFFFFF), save value in d.

Parameters

beg – The beg.
end – The end.
d – [inout] A DateTime to process.

Returns

Number of bytes parsed (must be 19 or 26), 0 if failed.

static DateTime Now() noexcept

Get current DateTime in UTC.

Returns: A DateTime.

static DateTime LocalNow() noexcept

Get current DateTime in local timezone.

Returns: A DateTime.

Private Members

int64_t microseconds_since_epoch_

struct YMDHMSF

#include <lgraph_date_time.h>

Representation of a DateTime in year, month, day, hour, minute, second, fraction.

Public Members

int year: The year, 0-9999.

unsigned month: The month, 1-12.

unsigned day: The day, 1-31.

unsigned hour: The hour, 0-23.

unsigned minute: The minute, 0-59.

unsigned second: The second, 0-59.

unsigned fraction: The fraction 000000-999999.

class TimeZone

#include <lgraph_date_time.h>

A class that represents a time zone.

Public Functions

explicit TimeZone(int time_diff_hours = 0)

Create a timezone which has time difference with UTC in hours time_diff_hours.

Throws: InvalidParameterError – Thrown if time_diff_hours is invalid.
Parameters: time_diff_hours – (Optional) Difference between local timezone and UTC. Must be > =-10 && <=14. Otherwise the function will throw.

DateTime FromUTC(const DateTime &dt) const

Convert a DateTime from UTC time to this time zone.

Throws: OutOfRangeError – Thrown if the resulting value is out of range.
Parameters: dt – DateTime in UTC time.
Returns: DateTime in local timezone.

DateTime ToUTC(const DateTime &dt) const

Convert a DateTime from this timezone to UTC time.

Throws: OutOfRangeError – Thrown if the resulting value is out of range.
Parameters: dt – DateTime in local timezone.
Returns: DateTime in UTC.

int64_t UTCDiffSeconds() const noexcept

Returns diff from UTC in seconds, this is used in Date and DateTime.

Returns: Number of seconds local timezone is from UTC.

int64_t UTCDiffHours() const noexcept

Returns diff from UTC in hours, this is used in Date and DateTime.

Returns: Number of hours local timezone is from UTC.

Public Static Functions

static const TimeZone &LocalTimeZone() noexcept

Get local timezone.

Returns: A const reference to local timezone.

static void UpdateLocalTimeZone() noexcept: Update local timezone, used only when daylight saving time changes. Daylight saving time may change after LocalTZ was initialized, in which case we need to update it. This function will update all references returned by LocalTimeZone().

Private Members

int64_t time_diff_microseconds_

Private Static Functions

static TimeZone GetLocalTZ()

static TimeZone &LocalTZ()