std::hash::BuildHasher

Trait std::hash::BuildHasher

pub trait BuildHasher {
    type Hasher: Hasher;
    fn build_hasher(&self) -> Self::Hasher;
}

A trait for creating instances of Hasher.

A BuildHasher is typically used (e.g. by HashMap) to create Hashers for each key such that they are hashed independently of one another, since Hashers contain state.

For each instance of BuildHasher, the Hashers created by build_hasher should be identical. That is, if the same stream of bytes is fed into each hasher, the same output will also be generated.

Examples

use std::collections::hash_map::RandomState;
use std::hash::{BuildHasher, Hasher};

let s = RandomState::new();
let mut hasher_1 = s.build_hasher();
let mut hasher_2 = s.build_hasher();

hasher_1.write_u32(8128);
hasher_2.write_u32(8128);

assert_eq!(hasher_1.finish(), hasher_2.finish());

Associated Types

Required Methods

use std::collections::hash_map::RandomState;
use std::hash::BuildHasher;

let s = RandomState::new();
let new_s = s.build_hasher();

Implementors

• impl<H> BuildHasher for BuildHasherDefault<H> where
    H: Default + Hasher, 
• impl BuildHasher for RandomState