Elixir

v1.8.1

Calendar behaviour View Source

This module defines the responsibilities for working with calendars, dates, times and datetimes in Elixir.

Currently it defines types and the minimal implementation for a calendar behaviour in Elixir. The goal of the Calendar features in Elixir is to provide a base for interoperability instead of full-featured datetime API.

For the actual date, time and datetime structures, see Date, Time, NaiveDateTime and DateTime.

Note the year, month, day, etc. designations are overspecified (i.e. an integer instead of 1..12 for months) because different calendars may have a different number of days per month, months per year and so on.

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Types

calendar()

A calendar implementation

date()

Any map/struct that contains the date fields

datetime()

Any map/struct that contains the datetime fields

day()
day_fraction()

The internal time format is used when converting between calendars

day_of_week()
era()
hour()
iso_days()

The internal date format that is used when converting between calendars

microsecond()

Microseconds with stored precision

minute()
month()
naive_datetime()

Any map/struct that contains the naive_datetime fields

second()
std_offset()

The time zone standard offset in seconds (not zero in summer times)

time()

Any map/struct that contains the time fields

time_zone()

The time zone ID according to the IANA tz database (e.g. Europe/Zurich)

time_zone_database()

Specifies the time zone database for calendar operations

utc_offset()

The time zone UTC offset in seconds

week()
year()
zone_abbr()

The time zone abbreviation (e.g. CET or CEST or BST etc.)

Functions

compatible_calendars?(calendar, calendar)

Returns true if two calendars have the same moment of starting a new day, false otherwise

get_time_zone_database()

Gets the current time zone database

put_time_zone_database(database)

Sets the current time zone database

truncate(microsecond_tuple, atom)

Returns a microsecond tuple truncated to a given precision (:microsecond, :millisecond or :second)

Callbacks

date_to_string(year, month, day)

Converts the date into a string according to the calendar

datetime_to_string(year, month, day, hour, minute, second, microsecond, time_zone, zone_abbr, utc_offset, std_offset)

Converts the datetime (with time zone) into a string according to the calendar

day_of_era(year, month, day)

Calculates the day and era from the given year, month, and day

day_of_week(year, month, day)

Calculates the day of the week from the given year, month, and day

day_of_year(year, month, day)

Calculates the day of the year from the given year, month, and day

day_rollover_relative_to_midnight_utc()

Define the rollover moment for the given calendar

days_in_month(year, month)

Returns how many days there are in the given year-month

leap_year?(year)

Returns true if the given year is a leap year

months_in_year(year)

Returns how many months there are in the given year

naive_datetime_from_iso_days(iso_days)

Converts iso_days/0 to the Calendar's datetime format

naive_datetime_to_iso_days(year, month, day, hour, minute, second, microsecond)

Converts the given datetime (without time zone) into the iso_days/0 format

naive_datetime_to_string(year, month, day, hour, minute, second, microsecond)

Converts the datetime (without time zone) into a string according to the calendar

quarter_of_year(year, month, day)

Calculates the quarter of the year from the given year, month, and day

time_from_day_fraction(day_fraction)

Converts day_fraction/0 to the Calendar's time format

time_to_day_fraction(hour, minute, second, microsecond)

Converts the given time to the day_fraction/0 format

time_to_string(hour, minute, second, microsecond)

Converts the time into a string according to the calendar

valid_date?(year, month, day)

Should return true if the given date describes a proper date in the calendar

valid_time?(hour, minute, second, microsecond)

Should return true if the given time describes a proper time in the calendar

year_of_era(year)

Calculates the year and era from the given year

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calendar() View Source 
calendar() :: module()

A calendar implementation

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date() View Source 
date() :: %{
  optional(any()) => any(),
  :calendar => calendar(),
  :year => year(),
  :month => month(),
  :day => day()
}

Any map/struct that contains the date fields

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datetime() View Source 
datetime() :: %{
  optional(any()) => any(),
  :calendar => calendar(),
  :year => year(),
  :month => month(),
  :day => day(),
  :hour => hour(),
  :minute => minute(),
  :second => second(),
  :microsecond => microsecond(),
  :time_zone => time_zone(),
  :zone_abbr => zone_abbr(),
  :utc_offset => utc_offset(),
  :std_offset => std_offset()
}

Any map/struct that contains the datetime fields

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day_fraction() View Source 
day_fraction() ::
  {parts_in_day :: non_neg_integer(), parts_per_day :: pos_integer()}

The internal time format is used when converting between calendars.

It represents time as a fraction of a day (starting from midnight). parts_in_day specifies how much of the day is already passed, while parts_per_day signifies how many parts there fit in a day.

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day_of_week() View Source 
day_of_week() :: non_neg_integer()

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iso_days() View Source 
iso_days() :: {days :: integer(), day_fraction()}

The internal date format that is used when converting between calendars.

This is the number of days including the fractional part that has passed of the last day since 0000-01-01+00:00T00:00.000000 in ISO 8601 notation (also known as midnight 1 January BC 1 of the proleptic Gregorian calendar).

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microsecond() View Source 
microsecond() :: {0..999_999, 0..6}

Microseconds with stored precision.

The precision represents the number of digits that must be used when representing the microseconds to external format. If the precision is 0, it means microseconds must be skipped.

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naive_datetime() View Source 
naive_datetime() :: %{
  optional(any()) => any(),
  :calendar => calendar(),
  :year => year(),
  :month => month(),
  :day => day(),
  :hour => hour(),
  :minute => minute(),
  :second => second(),
  :microsecond => microsecond()
}

Any map/struct that contains the naive_datetime fields

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std_offset() View Source 
std_offset() :: integer()

The time zone standard offset in seconds (not zero in summer times)

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time() View Source 
time() :: %{
  optional(any()) => any(),
  :hour => hour(),
  :minute => minute(),
  :second => second(),
  :microsecond => microsecond()
}

Any map/struct that contains the time fields

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time_zone() View Source 
time_zone() :: String.t()

The time zone ID according to the IANA tz database (e.g. Europe/Zurich)

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time_zone_database() View Source 
time_zone_database() :: module()

Specifies the time zone database for calendar operations.

Many functions in the DateTime module require a time zone database. By default, it uses the default time zone database returned by Calendar.get_time_zone_database/0, which defaults to Calendar.UTCOnlyTimeZoneDatabase which only handles "Etc/UTC" datetimes and returns {:error, :utc_only_time_zone_database} for any other time zone.

Other time zone databases (including ones provided by packages) can be configure as default either via configuration:

config :elixir, :time_zone_database, CustomTimeZoneDatabase

or by calling Calendar.put_time_zone_database/1.

See Calendar.TimeZoneDatabase for more information on custom time zone databases.

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utc_offset() View Source 
utc_offset() :: integer()

The time zone UTC offset in seconds

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zone_abbr() View Source 
zone_abbr() :: String.t()

The time zone abbreviation (e.g. CET or CEST or BST etc.)

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compatible_calendars?(calendar, calendar) View Source (since 1.5.0) 
compatible_calendars?(Calendar.calendar(), Calendar.calendar()) :: boolean()

Returns true if two calendars have the same moment of starting a new day, false otherwise.

If two calendars are not compatible, we can only convert datetimes and times between them. If they are compatible, this means that we can also convert dates as well as naive datetimes between them.

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get_time_zone_database() View Source (since 1.8.0) 
get_time_zone_database() :: time_zone_database()

Gets the current time zone database.

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put_time_zone_database(database) View Source (since 1.8.0) 
put_time_zone_database(time_zone_database()) :: :ok

Sets the current time zone database.

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truncate(microsecond_tuple, atom) View Source (since 1.6.0) 
truncate(Calendar.microsecond(), :microsecond | :millisecond | :second) ::
  Calendar.microsecond()

Returns a microsecond tuple truncated to a given precision (:microsecond, :millisecond or :second).

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date_to_string(year, month, day) View Source 
date_to_string(year(), month(), day()) :: String.t()

Converts the date into a string according to the calendar.

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datetime_to_string(year, month, day, hour, minute, second, microsecond, time_zone, zone_abbr, utc_offset, std_offset) View Source 
datetime_to_string(
  year(),
  month(),
  day(),
  hour(),
  minute(),
  second(),
  microsecond(),
  time_zone(),
  zone_abbr(),
  utc_offset(),
  std_offset()
) :: String.t()

Converts the datetime (with time zone) into a string according to the calendar.

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day_of_era(year, month, day) View Source 
day_of_era(year(), month(), day()) :: {non_neg_integer(), era()}

Calculates the day and era from the given year, month, and day.

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day_of_week(year, month, day) View Source 
day_of_week(year(), month(), day()) :: day_of_week()

Calculates the day of the week from the given year, month, and day.

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day_of_year(year, month, day) View Source 
day_of_year(year(), month(), day()) :: non_neg_integer()

Calculates the day of the year from the given year, month, and day.

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day_rollover_relative_to_midnight_utc() View Source 
day_rollover_relative_to_midnight_utc() :: day_fraction()

Define the rollover moment for the given calendar.

This is the moment, in your calendar, when the current day ends and the next day starts.

The result of this function is used to check if two calendars rollover at the same time of day. If they do not, we can only convert datetimes and times between them. If they do, this means that we can also convert dates as well as naive datetimes between them.

This day fraction should be in its most simplified form possible, to make comparisons fast.

Examples

  • If, in your Calendar, a new day starts at midnight, return {0, 1}.
  • If, in your Calendar, a new day starts at sunrise, return {1, 4}.
  • If, in your Calendar, a new day starts at noon, return {1, 2}.
  • If, in your Calendar, a new day starts at sunset, return {3, 4}.
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days_in_month(year, month) View Source 
days_in_month(year(), month()) :: day()

Returns how many days there are in the given year-month.

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leap_year?(year) View Source 
leap_year?(year()) :: boolean()

Returns true if the given year is a leap year.

A leap year is a year of a longer length than normal. The exact meaning is up to the calendar. A calendar must return false if it does not support the concept of leap years.

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months_in_year(year) View Source 
months_in_year(year()) :: month()

Returns how many months there are in the given year.

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naive_datetime_from_iso_days(iso_days) View Source 
naive_datetime_from_iso_days(iso_days()) ::
  {year(), month(), day(), hour(), minute(), second(), microsecond()}

Converts iso_days/0 to the Calendar's datetime format.

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naive_datetime_to_iso_days(year, month, day, hour, minute, second, microsecond) View Source 
naive_datetime_to_iso_days(
  year(),
  month(),
  day(),
  hour(),
  minute(),
  second(),
  microsecond()
) :: iso_days()

Converts the given datetime (without time zone) into the iso_days/0 format.

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naive_datetime_to_string(year, month, day, hour, minute, second, microsecond) View Source 
naive_datetime_to_string(
  year(),
  month(),
  day(),
  hour(),
  minute(),
  second(),
  microsecond()
) :: String.t()

Converts the datetime (without time zone) into a string according to the calendar.

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quarter_of_year(year, month, day) View Source 
quarter_of_year(year(), month(), day()) :: non_neg_integer()

Calculates the quarter of the year from the given year, month, and day.

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time_from_day_fraction(day_fraction) View Source 
time_from_day_fraction(day_fraction()) ::
  {hour(), minute(), second(), microsecond()}

Converts day_fraction/0 to the Calendar's time format.

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time_to_day_fraction(hour, minute, second, microsecond) View Source 
time_to_day_fraction(hour(), minute(), second(), microsecond()) ::
  day_fraction()

Converts the given time to the day_fraction/0 format.

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time_to_string(hour, minute, second, microsecond) View Source 
time_to_string(hour(), minute(), second(), microsecond()) :: String.t()

Converts the time into a string according to the calendar.

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valid_date?(year, month, day) View Source 
valid_date?(year(), month(), day()) :: boolean()

Should return true if the given date describes a proper date in the calendar.

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valid_time?(hour, minute, second, microsecond) View Source 
valid_time?(hour(), minute(), second(), microsecond()) :: boolean()

Should return true if the given time describes a proper time in the calendar.

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year_of_era(year) View Source 
year_of_era(year()) :: {year(), era()}

Calculates the year and era from the given year.