Name Rascal/Expressions/Values/DateTime

Synopsis Date and time values.

Syntax

1. $ Date
2. $ Time
3. $ DateTime

Types datetime

Usage import DateTime; (included in Prelude)

Details Equal FieldSelection GreaterThan GreaterThanOrEqual LessThan LessThanOrEqual NotEqual

Description Date, time, and datetime values are represented by the datetime type. datetime literals start with a $ and are made up of either a date, given in year, month, day of month order; a time, preceded by T and given in hour, minute, second, millisecond, (optional) timezone offset order; or a datetime, which is a date and a time, in the orders given above, and separated by a T.

The following fields provide access to information about the value, but cannot be set:

• isDate: returns true if the value is a date value, false if the value is a datetime or time value.
• isTime: returns true if the value is a time value, false if the value is a date or datetime value.
• isDateTime: returns true if the value is a datetime value, false if the value is a date or time value.
• justTime: returns the date component of a date or datetime value.
• justDate: returns the time component of a time or datetime value.
• century: returns the century component of a year for date or datetime values.

The following fields provide access to the individual components of date, time and datetime values, and can be accessed using DateTime/FieldSelection and be assigned using DateTime/FieldSelection:

• year
• month
• day
• hour
• minute
• second
• millisecond
• timezoneOffsetHours
• timezoneOffsetMinutes

Not all fields are available on all values as indicated by the following table:

Field	date	datetime	time
year	x	x
month	x	x
day	x	x
hour		x	x
minute		x	x
second		x	x
millisecond		x	x
timezoneOffsetHours		x	x
timezoneOffsetMinutes		x	x

The isDate, isTime, and isDateTime fields can be checked in advance to determine what kind of value is stored in a variable of type datetime.

The following operators are defined for DateTime:

• Equal: Equality on datetime values.
• FieldSelection: Select a field from a datetime value.
• GreaterThan: Greater than operator on datetime values.
• GreaterThanOrEqual: Greater than or equal operator on datetime values.
• LessThan: Less than operator on datetime values.
• LessThanOrEqual: Less than or equal operator on datetime values.
• NotEqual: Not equal operator on datetime values.

The following functions are defined for DateTime:

• createDate: Create a new date.
• createDateTime: Create a new datetime (with optional timezone offset).
• createDuration: Create a new duration representing the duration between the begin and end dates.
• createInterval: Given two datetime values, create an interval.
• createTime: Create a new time (with optional timezone offset).
• dateRangeByDay: Given an interval, return a list of days.
• daysDiff: Return the difference between two dates and/or datetimes in days.
• daysInInterval: Return the number of days in an interval, including the begin and end days.
• decrementDays: Decrement the days by a given amount or by 1.
• decrementHours: Decrement the hours by a given amount or by 1.
• decrementMilliseconds: Decrement the milliseconds by a given amount or by 1.
• decrementMinutes: Decrement the minutes by a given amount or by 1.
• decrementMonths: Decrement the months by a given amount or by 1.
• decrementSeconds: Decrement the seconds by a given amount or by 1.
• decrementYears: Decrement the years by a given amount or by 1.
• Duration: A duration of time, measured in individual years, months, etc.
• incrementDays: Increment the days by given amount or by 1.
• incrementHours: Increment the hours by a given amount or by 1.`
• incrementMilliseconds: Increment the milliseconds by a given amount or by 1.
• incrementMinutes: Increment the minutes by a given amount or by 1.
• incrementMonths: Increment the months by a given amount or by 1.
• incrementSeconds: Increment the seconds by a given amount or by 1.
• incrementYears: Increment the years by given amount or by 1.
• interval: A closed interval on the time axis.
• joinDateAndTime: Create a new datetime by combining a date and a time.
• now: Get the current datetime.
• parseDate: Parse an input date given as a string using the given format string.
• parseDateInLocale: Parse an input date given as a string using a specific locale and format string.
• parseDateTime: Parse an input datetime given as a string using the given format string.
• parseDateTimeInLocale: Parse an input datetime given as a string using a specific locale and format string.
• parseTime: Parse an input time given as a string using the given format string.
• parseTimeInLocale: Parse an input time given as a string using a specific locale and format string.
• printDate: Print an input date using the given format string.
• printDateInLocale: Print an input date using a specific locale and format string.
• printDateTime: Print an input datetime using the given format string.
• printDateTimeInLocale: Print an input datetime using a specific locale and format string.
• printTime: Print an input time using the given format string.
• printTimeInLocale: Print an input time using a specific locale and format string.
• splitDateTime: Split an existing datetime into a tuple with the date and the time.

Examples Examples of datetime values are:

rascal>$2010-07-15$;
datetime: 2010-07-15
rascal>$T07:15:23.123+0100$;
datetime: $T07:15:23.123+01:00$

Now introduce a datetime value and assign it to DT.

rascal>DT = $2010-07-15T09:15:23.123+03:00$;
datetime: $2010-07-15T09:15:23.123+03:00$

Here are examples of some datatime fields:

rascal>DT.isDateTime;
bool: true
rascal>DT.justDate;
datetime: 2010-07-15
rascal>DT.justTime;
datetime: $T09:15:23.123+03:00$
rascal>DT.century;
int: 20

Pitfalls In normal parlance, the year 2010 is in the 21th century. The century field, however, just returns the century component of a given year, e.g., for 2010 this is 20.

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