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autohash

Crates.io Documentation Rust

This crate provides AutoHashMap and AutoHashSet where the keys are self-hashed. The implementation is built on RawTable from hashbrown.

Keys implement the AutoHash trait for getting their hash value, instead of using a generic Hasher in the table with Hash keys. This may be useful when the type is already hash-like or has a saved hash, or if you don't want your type to implement Hash for some reason.

Example wrappers are included:

  • U64Hash(u64): Use a direct hash value as a key.
  • AutoHashed<T, H>: For T: Hash, H: Hasher + Default, this computes the hash automatically. This is effectively the same as using a normal hash map/set with S = BuildHasherDefault<H>, just specified on the key type instead.
  • MemoHashed<T, H>: For T: Hash, H: Hasher + Default, this computes the hash automatically when it is constructed -- for a precomputed/memoized hash.
  • RawHashed<T>: Pairs a value with its raw hash.

Change log

Usage

Add this to your Cargo.toml:

[dependencies]
autohash = "0.1"

Then:

use autohash::AutoHashMap;
use autohash::wrappers::U64Hash;

let mut map = AutoHashMap::new();
map.insert(U64Hash(1), "one");
map.insert(U64Hash(u64::MAX), "max");

This crate has the following Cargo features:

  • serde: Enables serde serialization support.
  • rayon: Enables rayon parallel iterator support.
  • inline-more: Adds inline hints to most functions, improving run-time performance at the cost of compilation time. (enabled by default)

License

Licensed under either of:

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.