ExtendedHasher

rustc_stable_hash

Trait ExtendedHasher 

Source 
pub trait ExtendedHasher: Hasher {
    type Hash;

    // Required method
    fn finish(self) -> Self::Hash;

    // Provided method
    fn short_write<const LEN: usize>(&mut self, bytes: [u8; LEN]) { ... }
}
Expand description

Extended Hasher trait for use with StableHasher.

It permits returning an arbitrary type as the Self::Hash type contrary to the Hasher trait which can only return u64. This is useful when the hasher uses a different representation.

§Example

use std::hash::Hasher;
use rustc_stable_hash::ExtendedHasher;

struct BogusHasher(u128);

impl Hasher for BogusHasher {
    fn write(&mut self, a: &[u8]) {
        // ...
    }

    fn finish(&self) -> u64 {
        self.0 as u64 // really bogus
    }
}

impl ExtendedHasher for BogusHasher {
    type Hash = u128;

    fn short_write<const LEN: usize>(&mut self, bytes: [u8; LEN]) {
        self.write(&bytes)
    }

    fn finish(self) -> Self::Hash {
        self.0
    }
}

Required Associated Types§

Source

type Hash

Type returned by the hasher.

Required Methods§

Source

fn finish(self) -> Self::Hash

Finalization method of the hasher to return the Hash.

Provided Methods§

Source

fn short_write<const LEN: usize>(&mut self, bytes: [u8; LEN])

Optimized version of Hasher::write but for small write.

Dyn Compatibility§

This trait is not dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety", so this trait is not object safe.

Implementors§