RecurrenceIterator does not support PERIOD values in RDATE (throws UnsupportedError at line 105)

[kozw]

Problem

In lib/src/semantic/recurrence/recurrence_iterator.dart, the RecurrenceIterator only supports DATE-TIME values in the RDATE property. If a PERIOD value is present, it throws an UnsupportedError at line 105.

Expected Behavior

RecurrenceIterator should support both DATE-TIME and PERIOD values in RDATE, as outlined in RFC 5545. Periods may represent event spans or ranges.

Steps to Reproduce

1. Provide a recurrence rule with RDATE containing a PERIOD value.
2. Attempt to iterate; observe that an UnsupportedError is thrown.

Suggested Solution

• Implement logic to handle PERIOD values in RDATE fields, consistent with RFC 5545 specification.
• Tests should include both DATE-TIME and PERIOD RDATE values.

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Reference:

• [RFC 5545, Section 3.3.5 - Recurrence Date/Times (RDATE)](https://datatracker. ietf.org/doc/html/rfc5545#section-3.3.5)
• See error thrown at line 105:

104|         if (rdate.isPeriod) {
105|           throw UnsupportedError(
106|             'RDATE with PERIOD values is not yet supported. '
107|             'Only RDATE with DATE-TIME values are currently supported.',
108|           );