paritytech / nohash-hasher

An implementation of `std :: hash :: Hasher` which does not hash at all.

NoHashHasher

For an enabled type T, a NoHashHasher<T> implements std::hash::Hasher and uses the value set by one of the write_{u8, u16, u32, u64, usize, i8, i16, i32, i64, isize} methods as its hash output.

NoHashHasher does not implement any hashing algorithm and can only be used with types which can be mapped directly to a numeric value. Out of the box NoHashHasher is enabled for u8, u16, u32, u64, usize, i8, i16, i32, i64, and isize. Types that should be used with NoHashHasher need to implement [IsEnabled] and by doing so assert that their Hash impl invokes only one of the Hasher::write_{u8, u16, u32, u64, usize, i8, i16, i32, i64, isize} methods exactly once.

License

Licensed under either of

• Apache License, Version 2.0 (LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0)
• MIT license (LICENSE-MIT or http://opensource.org/licenses/MIT)

at your option.

Contribution

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.

nohash-hasher's Issues

Doc Request: Usage of NoHashHasher<T> with HashMap::with_hasher(hasher)

Hey, thanks for the library! You saved me a bit of time making something like this for myself, but can I ask for an addition to the docs on how to use NoHashHasher<T> with the HashMap::with_hasher constructor?

Support for `char`-type

As char can be represented as a u32 by using '…' as u32, it would be helpful to add support for this type.

IntMap and IntSet don't implement the ```with_capacity``` constructor

I can't figure out why from looking at the source code, especially since IntMap and IntSet do implement the with_hasher and with_capacity_and_hasher constructors (which makes sense because they're type aliases of HashMap and HashSet respectively, so they should implement the same methods).