Struct Hashed

pub struct Hashed<V, S = FixedHasher> { /* private fields */ }

A pre-hashed value of a specific type. Pre-hashing enables memoization of hashes that are expensive to compute.

It also enables faster PartialEq comparisons by short circuiting on hash equality. See PassHash and PassHasher for a “pass through” BuildHasher and Hasher implementation designed to work with Hashed See PreHashMap for a hashmap pre-configured to use Hashed keys.

Implementations

impl<V: Hash, H: BuildHasher + Default> Hashed<V, H>

pub fn new(value: V) -> Self

Pre-hashes the given value using the BuildHasher configured in the Hashed type.

pub fn hash(&self) -> u64

The pre-computed hash.

Trait Implementations

impl<V: Clone, H> Clone for Hashed<V, H>

fn clone(&self) -> Self

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl<V: Debug, H> Debug for Hashed<V, H>

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

Formats the value using the given formatter.

impl<V, H> Deref for Hashed<V, H>

type Target = V

The resulting type after dereferencing.

fn deref(&self) -> &Self::Target

Dereferences the value.

impl<V, H> Hash for Hashed<V, H>

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

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<V: PartialEq, H> PartialEq for Hashed<V, H>

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

A fast impl of PartialEq that first checks that other’s pre-computed hash matches this value’s pre-computed hash.

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<V: Copy, H> Copy for Hashed<V, H>

impl<V: Eq, H> Eq for Hashed<V, H>