A crate for generating arrays of prime numbers at compile time.
#![no_std] compatible.
The crate is currently split into two modules, trial and sieve, which contain implementations of
prime related const functions that use trial division
or the Sieve of Eratosthenes in their implementations respectively.
The sieve needs O(n) memory, which means that the functions in the sieve module
need a const generic to be specified in order to compile.
The implementations in trial are slower, but do not need const generics unless they return an array.
Expect breaking changes fairly often. The crate will still try to adhere to semver.
Generate arrays of prime numbers with the function trial::primes
rust
const PRIMES: [u32; 10] = primes();
assert_eq!(PRIMES[5], 13);
assert_eq!(PRIMES, [2, 3, 5, 7, 11, 13, 17, 19, 23, 29]);
or with the type wrapper::Primes which ensures that a non-zero number of primes are generated
rust
const PRIMES: Primes<10> = Primes::new();
assert_eq!(PRIMES[5], 13);
assert_eq!(PRIMES, [2, 3, 5, 7, 11, 13, 17, 19, 23, 29]);
Creating a Primes<0> is a compile fail in const contexts and a panic otherwise.
There is one implementation of is_prime in trial and one in sieve
rust
use const_primes::{trial, sieve};
const CHECK_5: bool = trial::is_prime(5);
const CHECK_1009: bool = sieve::is_prime::<1009>();
assert!(CHECK_5);
assert!(CHECK_1009);
The Primes type also lets you reuse an array of already computed primes for primality testing.
rust
use const_primes::wrapper::Primes;
const CACHE: Primes<100> = Primes::new();
const CHECK_42: Option<bool> = CACHE.is_prime(42);
const CHECK_541: Option<bool> = CACHE.is_prime(541);
const CHECK_1000: Option<bool> = CACHE.is_prime(1000);
assert_eq!(CHECK_42, Some(false));
assert_eq!(CHECK_541, Some(true));
assert_eq!(CHECK_1000, None);
The function sieve::primalities lets you compute the prime status of all integers below a given value
rust
use const_primes::sieve::primalities;
const PRIME_STATUS: [bool; 10] = primalities();
assert_eq!(PRIME_STATUS, [false, false, true, true, false, true, false, true, false, false]);
Licensed under either of
at your option.
Contributions are welcome!
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.