Phase 2 of docs/OWN-STORE.md, the engine half. RecurrenceExpander turns a
stored rule set into its occurrences at read time — no materialised
instances table, so none of its staleness bugs exist. Each occurrence is
returned as its RECURRENCE-ID anchor, which is what the seam now
addresses occurrences by.
Expansion is bounded two ways: the window end, and a hard occurrence
ceiling. The iterator is fast-forwarded to the window start first, so a
FREQ=MINUTELY series anchored years back doesn't scan millions of
instances to emit one.
Three things lib-recur 0.12.2 forced. RecurrenceSet.iterator injects the
start itself, so DTSTART is in the set for free and EXDATE can remove it
(RFC 5545 §3.8.5.3). Its window end is exclusive. And a floating UNTIL
against a zoned start throws, so the UNTIL's local fields are re-read in
the series zone — the vendored provider worked around the same thing via
TimeZone.getDefault(), which isn't deterministic.
Malformed RRULE/RDATE/EXDATE values are dropped, not thrown: a task with
an unparseable stored rule still has to appear.
38 tests. Multi-occurrence expansion has no provider behaviour to compare
against, so the reference is RFC 5545 directly — daily/weekly/monthly/
yearly, COUNT, UNTIL, a Europe/Berlin DST boundary, all-day series pinned
to UTC midnight, RDATE, EXDATE, and an unbounded rule hitting both bounds.
Jean-Luc Makiola
829a27da82