RecurrenceRule

When something recurs (RFC 5545): its first occurrence as a local time in its zone, a line feed, then its rule: DTSTART;TZID=Europe/London:20261026T093000\nRRULE:FREQ=WEEKLY;BYDAY=MO. temporal.occurrences gives the next ones.

Time and calendar; not ordered; since Jadpo 0.1.0.

Make one

Build one from its text, RecurrenceRule("DTSTART;TZID=Europe/London:20261026T093000 RRULE:FREQ=WEEKLY;BYDAY=MO"), which checks it: text that isn't one breaks format.

text.parse(raw, as: RecurrenceRule) reads one from its text; text that isn't one at all fails malformed, such as FREQ=WEEKLY;BYDAY=MO or "".

Text, JSON and storage

text.from writes its canonical text, the one form text.parse reads back. JSON sends its canonical text as a string.

It is stored in one column named for the field, of type text. DTSTART;TZID=Europe/London:20260130T170000\nRRULE:FREQ=MONTHLY;BYDAY=-1FR;UNTIL=20261231T235959Z is stored as E'DTSTART;TZID=Europe/London:20260130T170000\nRRULE:FREQ=MONTHLY;BYDAY=-1FR;UNTIL=20261231T235959Z'.

Shown to people

text.format(value, locale:) shows it to people in their locale.

With locale: Locale.en_gb:

Operations

• temporal.occurrences(rule: RecurrenceRule, from: T, count: Int) -> List<ZonedTime>: The next count occurrences of rule at or after from, in its zone (RFC 5545): fewer when the rule ends first; count is from 1 to 1000, so an unbounded rule is never expanded without a bound. From a date, the days they fall on, List<CalendarDate>, which a rule on dates gives; from an Instant, a timed rule's local times.

Like every standard type, it also has the contract's own operations: text.parse, text.from, text.format, json.read, json.write and ==. It isn't ordered, so < and sorting don't take it. Every standard type meets one contract says how they work.