ice_cube - Easy schedule expansion

gem install ice_cube

ice_cube is a ruby library for easily handling repeated events (schedules). The API is modeled after iCalendar events, in a pleasant Ruby syntax. The power lies in the ability to specify multiple rules, and have ice_cube quickly figure out whether the schedule falls on a certain date (.occurs_on?), or what times it occurs at (.occurrences, .first, .all_occurrences).

Imagine you want:

Every friday the 13th that falls in October

You would write:

schedule = IceCube::Schedule.new
schedule.add_recurrence_rule(
  IceCube::Rule.yearly.day_of_month(13).day(:friday).month_of_year(:october)
)

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Quick Introductions

• Presentation from Lone Star Ruby Conf (slides, YouTube)
• Quick Introduction
• Documentation Website

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With ice_cube, you can specify (in increasing order of precedence):

• Recurrence Rules - Rules on how to include recurring times in a schedule
• Recurrence Times - To specifically include in a schedule
• Exception Times - To specifically exclude from a schedule

Example: Specifying a recurrence with an exception time. Requires "rails/activesupport" (gem install 'activesupport').

require 'ice_cube'
require 'active_support/time'

schedule = IceCube::Schedule.new(now = Time.now) do |s|
  s.add_recurrence_rule(IceCube::Rule.daily.count(4))
  s.add_exception_time(now + 1.day)
end

# list occurrences until end_time (end_time is needed for non-terminating rules)
occurrences = schedule.occurrences(end_time) # [now]

# or all of the occurrences (only for terminating schedules)
occurrences = schedule.all_occurrences # [now, now + 2.days, now + 3.days]

# or check just a single time
schedule.occurs_at?(now + 1.day)  # false
schedule.occurs_at?(now + 2.days) # true

# or check just a single day
schedule.occurs_on?(Date.today) # true

# or check whether it occurs between two dates
schedule.occurs_between?(now, now + 30.days)          # true
schedule.occurs_between?(now + 4.days, now + 30.days) # false

# or the first (n) occurrences
schedule.first(2) # [now, now + 2.days]
schedule.first    # now

# or the last (n) occurrences (if the schedule terminates)
schedule.last(2) # [now + 2.days, now + 3.days]
schedule.last    # now + 3.days

# or the next occurrence
schedule.next_occurrence(from_time)     # defaults to Time.now
schedule.next_occurrences(4, from_time) # defaults to Time.now
schedule.remaining_occurrences          # for terminating schedules

# or the previous occurrence
schedule.previous_occurrence(from_time)
schedule.previous_occurrences(4, from_time)

# or include prior occurrences with a duration overlapping from_time
schedule.next_occurrences(4, from_time, spans: true)
schedule.occurrences_between(from_time, to_time, spans: true)

# or give the schedule a duration and ask if occurring_at?
schedule = IceCube::Schedule.new(now, duration: 3600)
schedule.add_recurrence_rule IceCube::Rule.daily
schedule.occurring_at?(now + 1800) # true
schedule.occurring_between?(t1, t2)

# using end_time also sets the duration
schedule = IceCube::Schedule.new(start = Time.now, end_time: start + 3600)
schedule.add_recurrence_rule IceCube::Rule.daily
schedule.occurring_at?(start + 3599) # true
schedule.occurring_at?(start + 3600) # false

# take control and use iteration
schedule = IceCube::Schedule.new
schedule.add_recurrence_rule IceCube::Rule.daily.until(Date.today + 30)
schedule.each_occurrence { |t| puts t }

The reason that schedules have durations and not individual rules, is to maintain compatibility with the ical RFC: http://www.kanzaki.com/docs/ical/rrule.html

To limit schedules use count or until on the recurrence rules. Setting end_time on the schedule just sets the duration (from the start time) for each occurrence.

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Time Zones and ActiveSupport vs. Standard Ruby Time Classes

ice_cube works great without ActiveSupport but only supports the environment's single "local" time zone (ENV['TZ']) or UTC. To correctly support multiple time zones (especially for DST), you should require 'active_support/time'.

A schedule's occurrences will be returned in the same class and time zone as the schedule's start_time. Schedule start times are supported as:

• Time.local (default when no time is specified)
• Time.utc
• ActiveSupport::TimeWithZone (with Time.zone.now, Time.zone.local, time.in_time_zone(tz))
• DateTime (deprecated) and Date are converted to a Time.local

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Persistence

ice_cube implements its own hash-based .to_yaml, so you can quickly (and safely) serialize schedule objects in and out of your data store

It also supports partial serialization to/from ICAL. Parsing datetimes with time zone information is not currently supported.

yaml = schedule.to_yaml
IceCube::Schedule.from_yaml(yaml)

hash = schedule.to_hash
IceCube::Schedule.from_hash(hash)

ical = schedule.to_ical
IceCube::Schedule.from_ical(ical)

---

Using your words

ice_cube can provide ical or string representations of individual rules, or the whole schedule.

rule = IceCube::Rule.daily(2).day_of_week(tuesday: [1, -1], wednesday: [2])

rule.to_ical # 'FREQ=DAILY;INTERVAL=2;BYDAY=1TU,-1TU,2WE'

rule.to_s # 'Every 2 days on the last and 1st Tuesdays and the 2nd Wednesday'

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Some types of Rules

There are many types of recurrence rules that can be added to a schedule:

Daily

# every day
schedule.add_recurrence_rule IceCube::Rule.daily

# every third day
schedule.add_recurrence_rule IceCube::Rule.daily(3)

Weekly

# every week
schedule.add_recurrence_rule IceCube::Rule.weekly

# every other week on monday and tuesday
schedule.add_recurrence_rule IceCube::Rule.weekly(2).day(:monday, :tuesday)

# for programmatic convenience (same as above)
schedule.add_recurrence_rule IceCube::Rule.weekly(2).day(1, 2)

# specifying a weekly interval with a different first weekday (defaults to Sunday)
schedule.add_recurrence_rule IceCube::Rule.weekly(1, :monday)

Monthly (by day of month)

# every month on the first and last days of the month
schedule.add_recurrence_rule IceCube::Rule.monthly.day_of_month(1, -1)

# every other month on the 15th of the month
schedule.add_recurrence_rule IceCube::Rule.monthly(2).day_of_month(15)

Monthly rules will skip months that are too short for the specified day of month (e.g. no occurrences in February for day_of_month(31)).

Monthly (by day of Nth week)

# every month on the first and last tuesdays of the month
schedule.add_recurrence_rule IceCube::Rule.monthly.day_of_week(tuesday: [1, -1])

# every other month on the first monday and last tuesday
schedule.add_recurrence_rule IceCube::Rule.monthly(2).day_of_week(
  monday: [1],
  tuesday: [-1]
)

# for programmatic convenience (same as above)
schedule.add_recurrence_rule IceCube::Rule.monthly(2).day_of_week(1 => [1], 2 => [-1])

Yearly (by day of year)

# every year on the 100th days from the beginning and end of the year
schedule.add_recurrence_rule IceCube::Rule.yearly.day_of_year(100, -100)

# every fourth year on new year's eve
schedule.add_recurrence_rule IceCube::Rule.yearly(4).day_of_year(-1)

Yearly (by month of year)

# every year on the same day as start_time but in january and february
schedule.add_recurrence_rule IceCube::Rule.yearly.month_of_year(:january, :february)

# every third year in march
schedule.add_recurrence_rule IceCube::Rule.yearly(3).month_of_year(:march)

# for programmatic convenience (same as above)
schedule.add_recurrence_rule IceCube::Rule.yearly(3).month_of_year(3)

BYSETPOS (select the nth occurrence)

BYSETPOS selects the nth occurrence within each interval after all other BYxxx filters/expansions are applied. Use positive values (from the start) or negative values (from the end). Repeated values do not duplicate occurrences, and positions beyond the set size yield no occurrence for that interval. RFC 5545 requires BYSETPOS to be used with another BYxxx rule part; IceCube allows BYSETPOS without another BYxxx and applies it to the single occurrence in each interval.

# last weekday of the month
schedule.add_recurrence_rule(
  IceCube::Rule.monthly.day(:monday, :tuesday, :wednesday, :thursday, :friday).by_set_pos(-1)
)

# second occurrence in each day's expanded set
schedule.add_recurrence_rule(
  IceCube::Rule.daily.hour_of_day(9, 17).by_set_pos(2)
)

Note: If you expand with BYHOUR/BYMINUTE/BYSECOND, any unspecified smaller time components are inherited from the schedule's start_time.

Hourly (by hour of day)

# every hour on the same minute and second as start date
schedule.add_recurrence_rule IceCube::Rule.hourly

# every other hour, on mondays
schedule.add_recurrence_rule IceCube::Rule.hourly(2).day(:monday)

Minutely (every N minutes)

# every 10 minutes
schedule.add_recurrence_rule IceCube::Rule.minutely(10)

# every hour and a half, on the last tuesday of the month
schedule.add_recurrence_rule IceCube::Rule.minutely(90).day_of_week(tuesday: [-1])

Secondly (every N seconds)

# every second
schedule.add_recurrence_rule IceCube::Rule.secondly

# every 15 seconds between 12:00 - 12:59
schedule.add_recurrence_rule IceCube::Rule.secondly(15).hour_of_day(12)

---

recurring_select

The team over at GetJobber have open-sourced RecurringSelect, which makes working with IceCube easier in a Rails app via some nice helpers.

Check it out at https://github.com/GetJobber/recurring_select

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Contributors

https://github.com/ice-cube-ruby/ice_cube/graphs/contributors

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Issues?

Use the GitHub issue tracker

Contributing

• Contributions are welcome - I use GitHub for issue tracking (accompanying failing tests are awesome) and feature requests
• Submit via fork and pull request (include tests)
• If you're working on something major, shoot me a message beforehand