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, H> Hashed<V, H>

where V: Hash, H: BuildHasher + Default,

pub fn new(value: V) -> Hashed<V, H>

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, H> Clone for Hashed<V, H>

where V: Clone,

fn clone(&self) -> Hashed<V, H>

Returns a copy of the value.

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

Performs copy-assignment from source.

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

where V: Debug,

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

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) -> &<Hashed<V, H> as Deref>::Target

Dereferences the value.

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

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

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

where V: PartialEq,

fn eq(&self, other: &Hashed<V, H>) -> 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, H> Copy for Hashed<V, H>

where V: Copy,

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

where V: Eq,