Enum ScanKind 

#[non_exhaustive]
#[repr(u16)]
pub enum ScanKind {
    Cumsum = 0,
    Cumprod = 1,
    Cummax = 2,
    Cummin = 3,
    LogCumsumExp = 4,
}

Scan (associative prefix) op discriminant — category F from the comprehensive plan.

Stored as u16 in crate::KernelSku::op when category == OpCategory::Scan. Output shape equals input shape — scans are length-preserving along the scan axis (in contrast with reductions, which collapse the axis to size 1). Inclusive scan by default (PyTorch convention: y[i] = op(x[0], x[1], …, x[i])). Direction is controlled by the descriptor’s reverse flag.

Today wired: {Cumsum} × {f32, f16, bf16, f64} (FW + BW) as the scan trailblazer. Cumprod / Cummax / Cummin land in fanout; LogCumsumExp and the JAX-style generic associative_scan are reserved-but-deferred (numerics / generic-functor work).

Variants (Non-exhaustive)

Non-exhaustive enums could have additional variants added in future. Therefore, when matching against variants of non-exhaustive enums, an extra wildcard arm must be added to account for any future variants.

Cumsum = 0

y[i] = Σ_{j ≤ i} x[j] — inclusive prefix sum.

Cumprod = 1

y[i] = ∏_{j ≤ i} x[j] — inclusive prefix product.

Cummax = 2

y[i] = max(x[0..=i]) — running maximum.

Cummin = 3

y[i] = min(x[0..=i]) — running minimum.

LogCumsumExp = 4

y[i] = log(Σ_{j ≤ i} exp(x[j])) — numerically stable (running max subtraction). Reserved.

Trait Implementations

impl Clone for ScanKind

fn clone(&self) -> ScanKind

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Copy for ScanKind

impl Debug for ScanKind

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

Formats the value using the given formatter.

impl Eq for ScanKind

impl Hash for ScanKind

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

where __H: Hasher,

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 ScanKind

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

Tests for self and other values to be equal, and is used by ==.

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

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl StructuralPartialEq for ScanKind