Struct RecalcContext 

pub struct RecalcContext { /* private fields */ }

The deterministic context a recalc evaluates against (scope ADR Decision 3).

Same workbook + same RecalcContext ⇒ byte-identical recomputed grid. The context is an input to recalc, never part of the workbook value or its JSON (value-object ADR): two recalcs with different contexts legitimately differ, and the property tests compare like-context runs only.

Volatile pinning

• NOW() / TODAY() are pinned: timestamp_ms (a UTC instant) is converted to a local spreadsheet serial against the vendored timezone (chrono-tz, not the host tz database), and that serial is passed to core’s evaluate_with_resolver_at. The conversion is the determinism envelope: same instant + same timezone + same truecalc version ⇒ same serial.
• RAND() / RANDBETWEEN() / RANDARRAY() carry a rng_seed and a per-cell key helper (Self::rng_key) implementing the ADR’s prf(seed, sheet_index, row, col, draw_index) scheme. Caveat: core’s RNG functions presently read the system clock directly and take no per-cell key (crates/core/.../math/rand), so the workbook layer cannot yet inject this seed into them — full PRF-keyed RNG determinism requires a core change and is tracked for P4. rng_seed is carried now so the API is stable; recalc therefore guarantees determinism for non-RNG workbooks (which is every P3.6 fixture).

Implementations

impl RecalcContext

pub fn new(timestamp_ms: i64, tz: &str, rng_seed: u64) -> Option<Self>

Builds a context from a UTC instant (Unix milliseconds), an IANA timezone id (e.g. "Etc/GMT", "America/New_York"), and an RNG seed.

Returns None if tz is not a known IANA id in the vendored database.

pub fn timestamp_ms(&self) -> i64

The UTC instant this context pins volatile time to (Unix milliseconds).

pub fn timezone(&self) -> Tz

The vendored IANA timezone the instant is localized against.

pub fn rng_seed(&self) -> u64

The RNG seed keying deterministic per-cell draws.

pub fn now_serial(&self) -> Option<f64>

The local spreadsheet serial datetime this context pins NOW()/TODAY() to: the UTC timestamp_ms rendered into timezone, expressed as days since the 1899-12-30 epoch (integer part) plus time-of-day (fraction) — the now_serial core’s evaluate_at family consumes.

Returns None only if the instant is unrepresentable (e.g. out of chrono’s range), which cannot happen for any realistic timestamp.

pub fn now_utc_nanos(&self) -> Option<i64>

The pinned “now” as an absolute UTC instant in nanoseconds, for the zone-aware TZNOW. Derived from the same timestamp_ms as now_serial, so NOW() and TZNOW() share one deterministic clock.

pub fn rng_key( &self, sheet_index: u32, row: u32, col: u32, draw_index: u32, ) -> u64

The ADR’s per-draw RNG key prf(rng_seed, sheet_index, row, col, draw_index), a deterministic, order-independent mixing of the cell identity into the seed.

Exposed (and unit-tested) so the keying scheme is fixed and ready for the core integration that will consume it; see the type-level caveat.

Trait Implementations

impl Clone for RecalcContext

fn clone(&self) -> RecalcContext

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for RecalcContext

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

Formats the value using the given formatter.

impl Eq for RecalcContext

impl PartialEq for RecalcContext

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

Equality operator ==.

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

Inequality operator !=.

impl StructuralPartialEq for RecalcContext