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(** Resolution across a whole liturgical year (spec §2.4).
Transfers make per-date resolution impossible to do correctly: resolving
25 March can push a feast onto 26 March, and RG 97-98 has coinciding
I-class feasts transfer in table order, which needs global knowledge of
the whole year. So [year] is the primitive -- it resolves every date in
one pass -- and [day] is derived: it finds the liturgical year containing
a date and indexes into it. Both are pure; neither caches.
This module resolves each day's temporal-vs-sanctoral contest but does
not yet place deferred transfers (RG 96-98): a losing candidate the
rite's rules send to [Precedence.Transfer] is absent from the result
entirely on this pass -- not observed, not commemorated, and
[transferred_in]/[transferred_out] both stay [None] everywhere. Task 6
adds the fixed-point placement pass that closes this gap. *)
(** [year rite layer y] resolves every day of the liturgical year that opens
in civil year [y]: from [rite.year_start y] through the day before
[rite.year_start (y + 1)], inclusive of both ends.
Total over 1583..9999, including the boundary years:
- At [y] = 9999, [rite.year_start (y + 1)] would ask for civil year
10000, out of {!Date}'s domain (this is the bug Plan 2 shipped in
[Validate] and later fixed). The end of the walk clamps to 31 December
9999 instead of computing that call; the returned year comes back
truncated to whatever the rite's own temporal cycle covers between
[rite.year_start 9999] and the last day of that civil year, not
un-computable.
- Symmetrically, [y] < 1583 clamps the start of the walk to 1 January
1583 instead of calling [rite.year_start y] on an out-of-domain civil
year. [year] is never called this way directly by anything in this
module; {!day} is the only caller that can reach [y] = 1582 (one below
the floor, never lower), when the date it was asked about sits in civil
year 1583 before that year's own [rite.year_start] -- i.e. the sliver
whose true liturgical year opened in civil year 1582, which the domain
cannot represent. Calling [year] with such a [y] directly is also safe:
it returns exactly that truncated sliver. *)
val year : ('s, 'r) Rite.t -> 'r Layer.t -> int -> ('s, 'r) Liturgical_day.t array
(** [day rite layer date] finds the liturgical year containing [date] -- the
year [y] with [rite.year_start y <= date < rite.year_start (y + 1)] --
and returns its slot for [date]. Recomputes that whole year on every
call: pure, no cache, no mutable state. Acceptable cost for the natural
usage (dump a year, sweep years for validation), which pays it once. *)
val day : ('s, 'r) Rite.t -> 'r Layer.t -> Date.t -> ('s, 'r) Liturgical_day.t
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