Enum CalendarPeriod 

pub enum CalendarPeriod {
    Day,
    Week,
    Month,
    Quarter,
    Year,
}

A calendar period. Periods are anchored to the calendar, never to an arbitrary start date: months begin on the 1st, quarters on Jan/Apr/Jul/Oct 1, years on Jan 1, and weeks on the ISO Monday.

Deliberate divergence from Fava (quarters)

Fava’s _IntervalQuarter.get_prev tests date.month > i where it needs >=, so it puts April in Q1, July in Q2 and October in Q3 — every quarter boundary month falls into the preceding quarter. Reported as beancount/fava#2318. rustledger anchors quarters correctly, per the project’s Python-compatibility policy: match correct behavior, not bugs. A custom "budget" on a "quarterly" interval therefore accrues over different boundaries than Fava’s budget view for those three months.

Variants

Day

One calendar day.

Week

An ISO week, starting Monday.

Month

A calendar month (28, 29, 30 or 31 days).

Quarter

A calendar quarter, anchored at Jan/Apr/Jul/Oct 1.

Year

A calendar year (365 or 366 days).

Implementations

impl CalendarPeriod

pub fn start_of(self, day: NaiveDate) -> NaiveDate

The first day of the period containing day.

Falls back to day itself if the truncated date would be out of range, which keeps this total rather than panicking on ledger-derived dates.

For month, quarter and year that fallback is unreachable: the 1st of a real month always exists. For WEEK it is reachable at the very start of the representable calendar, where the containing ISO week begins before NaiveDate::MIN and there is no Monday to return; the result then is the day itself, NOT a week start. No ledger reaches that date, but the saturation is real and this says so rather than implying stricter semantics than the code provides.

pub fn next_start(self, start: NaiveDate) -> Option<NaiveDate>

The first day of the period after the one starting at start, or None when that date is outside the representable range.

start is expected to be a period start (the output of Self::start_of); the difference between this and start is the period’s true calendar length, which is what makes a per-day accrual divide by 28/29/30/31 for a month and 365/366 for a year.

Returning None rather than saturating to start is deliberate: a caller measuring the period’s length would otherwise get zero and, after the usual .max(1) guard, divide by a single day — inflating a yearly budget by ~365x near the end of the representable range, silently and with no error anywhere.

pub fn period_days(self, start: NaiveDate) -> i64

The calendar length, in days, of the period starting at start.

Equal to the gap to Self::next_start wherever that date exists. The final period of the representable calendar has no representable next start, but its LENGTH is still well defined, and this returns it: a day and a week are fixed-length, and month, quarter and year boundaries all coincide with the end of the calendar, so the span to the last representable day is the whole period.

Pro-rata accrual needs the length, not the boundary date. Deriving the length from next_start alone forced callers to give up on the final period entirely — a budget was reported as 0.00 for a window inside it, which reads as “nothing budgeted” rather than “cannot say”.

Trait Implementations

impl Clone for CalendarPeriod

fn clone(&self) -> CalendarPeriod

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Copy for CalendarPeriod

impl Debug for CalendarPeriod

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Eq for CalendarPeriod

impl Hash for CalendarPeriod

fn hash<__H: Hasher>(&self, state: &mut __H)

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl PartialEq for CalendarPeriod

fn eq(&self, other: &CalendarPeriod) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl StructuralPartialEq for CalendarPeriod