Struct Digest 

pub struct Digest<const N: usize = 1>(/* private fields */);

A fixed-size rolling hash of an append-only history, usable as a cheap, allocation-free Game::Infoset key.

Unlike History it keeps no structure – only N independent 64-bit hash lanes – so it is Copy and every operation is O(N) with no heap allocation. The trade-off is that it is lossy: two distinct histories whose digests collide become the same infoset, silently merging their regret.

N picks that trade-off. Each lane is its own rolling hash, salted by its index, so a collision needs all N lanes to coincide at once – roughly a 2^(64*N) chance. The default Digest<1> is most compact but a collision grows likely as the distinct-history count approaches 2^32; Digest<2> pushes that to 2^64 (negligible at any feasible game size) and Digest<4> further still, each lane costing 8 more bytes of key. Prefer any of them only for astronomically large games where avoiding allocation matters more than the residual risk; otherwise use the exact History.

Implementations

impl<const N: usize> Digest<N>

pub fn new() -> Self

The digest of an empty history.

pub fn push(self, value: &impl Hash) -> Digest<N>

The digest with value folded in. O(N) and allocation-free.

Trait Implementations

impl<const N: usize> Clone for Digest<N>

fn clone(&self) -> Digest<N>

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl<const N: usize> Copy for Digest<N>

impl<const N: usize> Debug for Digest<N>

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

Formats the value using the given formatter.

impl<const N: usize> Default for Digest<N>

fn default() -> Self

Returns the “default value” for a type.

impl<const N: usize> Eq for Digest<N>

impl<const N: usize> Hash for Digest<N>

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<const N: usize> PartialEq for Digest<N>

fn eq(&self, other: &Digest<N>) -> 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<const N: usize> StructuralPartialEq for Digest<N>