Hashable Map

This crate provides simple wrappers HashableMap and HashableSet that implement Hash around std::collections::HashMap and std::collections::HashSet without any additional dependencies.

Implementation Details

The Hash implementation of HashableMap and HashableSet respects the required property

k1 == k2 -> hash(k1) == hash(k2)

In other words, if two keys are equal, their hashes must also be equal.

The implementation is generic over all BuildHasher implementations, which means you can use this crate with the default RandomState as well as other hash builder implementations such as FxBuildHasher. The only requirement is that the hasher built by the hash builder implements Default, and that the default implementation results in the same hashes over different instances. This requirement is due to the fact that to compute the hash of the entries, this crate uses instances of the defaut hasher built by the hash builder. More formally, to construct the hashes for entries, we use an instance of D::default(), where S: BuildHasher<Hasher = D>, D: Hasher + Default. The hashes of the entries are then added by using the commutative operator wrapping_add such that different orders of entries still result in the same hash, which is required for satisfying the Hash property stated above.

Serde Support

This crate has the option to enable support for serialization and deserialization by enabling the serde feature.