Crate quickphf

QuickPHF is a Rust crate that allows you to use static compile-time generated hash maps and hash sets using PTHash perfect hash functions.

This crate only contains the runtime code required for using such structures. To generate them, look at the quickphf_codegen crate instead.

The minimum supported Rust version is 1.56. This crate is #![no_std] and #![forbid(unsafe_code)].

Features

• Provides 3 perfect hash function-backed data structures: PhfMap and PhfSet, which, for ease of use, mimic the immutable part of the interface of the standard library HashMap and HashSet; and RawPhfMap, which is a hash map that does not store its keys.
• About twice as fast as phf at lookup, and more than 10 times faster at construction.
• Uses a Rust implementation of Wang Yi’s wyhash algorithm for hashing.
• Uses the quickdiv crate to speed up modulo computations.
• Very low memory usage: no unused capacity and less than a byte of overhead per entry.

Example

use quickphf::examples::*;

// You can use `PhfMap` or `PhfSet` just like `HashMap` or `HashSet`.
assert_eq!(FOURTH_POWERS_TO_ROOTS.get(&4096), Some(&8));
assert_eq!(FOURTH_POWERS_TO_ROOTS.get(&17), None);

assert!(PRIME_DIGITS.contains(&3));
assert_eq!(PRIME_DIGITS.len(), 4);

// With a `RawPhfMap` you would mostly use the `get` method. Note
// that it directly returns a &T instead of an Option<&T>.
assert_eq!(HOLIDAYS_PER_MONTH.get("jul"), &1);

// If you query for an invalid key, it will silently return an
// arbitrary answer.
let valid_reference = HOLIDAYS_PER_MONTH.get("purple");

Modules

• map
  An immutable hash table constructed at compile time with perfect hashing.
• raw_map
  An immutable hash table constructed at compile time with perfect hashing which does not store its keys.
• set
  An immutable set constructed at compile time with perfect hashing.

Structs

• PhfMap
  An immutable hash table constructed at compile time with perfect hashing.
• PhfSet
  An immutable set constructed at compile time with perfect hashing.
• RawPhfMap
  An immutable hash table constructed at compile time with perfect hashing which does not store its keys.