[](https://travis-ci.org/HenningTimm/rust-tab-hash)
[](https://crates.io/crates/tab-hash)
[](https://opensource.org/licenses/MIT)
[](https://docs.rs/tab-hash)
# tab-hash - Tabulation Hashing for Rust
This crate offers rust implementations of simple and twisted tabulation hashing for 32-bit und 64-bit integer values.
Instatiating `Tab32Simple` or `Tab32Twisted` (or their 64-bit counterparts) will initialize a table and
create a random hash function from the respective hash family.
The hash values of an integer key is computed by calling its `hash` method.
## Example:
```rust
use tab_hash::Tab32Simple;
fn main() {
let keys = vec![0, 8, 15, 47, 11];
let simple = Tab32Simple::new();
for k in keys {
println!("{}", simple.hash(k));
}
}
```
To reproduce hashes, save the table used by the hash function.
The function can be recreated using the `with_table` constructor.
```rust
use tab_hash::Tab64Twisted;
fn main() {
let key = 42;
let twisted_1 = Tab64Twisted::new();
let twisted_2 = Tab64Twisted::with_table(twisted_1.get_table());
let twisted_3 = Tab64Twisted::new();
assert_eq!(twisted_1.hash(key), twisted_2.hash(key));
assert_ne!(twisted_1.hash(key), twisted_3.hash(key));
}
```
## Note:
These hash functions do not implement the `std::hash::Hasher` trait,
since they do not work on arbitrary length byte streams.
The 64-bit version of twisted tabulation hashing (`Tab64Twisted`) requires 128-bit operations (see [here](https://doi.org/10.1137/1.9781611973105.16)).
## Literature:
This implementation is based on the articles of Mihai Pătraşcu and Mikkel Thorup:
- [Simple Tabulation Hashing](http://dx.doi.org/10.1145/1993636.1993638)
- [Twisted Tabulation Hashing](https://doi.org/10.1137/1.9781611973105.16)