#[cfg(feature = "std")]
use rand::RngCore;
use rand::{
distributions::{Distribution, Standard},
prelude::StdRng,
Rng,
};
pub use rand;
pub trait UniformRand: Sized {
fn rand<R: Rng + ?Sized>(rng: &mut R) -> Self;
}
impl<T> UniformRand for T
where
Standard: Distribution<T>,
{
#[inline]
fn rand<R: Rng + ?Sized>(rng: &mut R) -> Self {
rng.sample(Standard)
}
}
fn test_rng_helper() -> StdRng {
use rand::SeedableRng;
let seed = [
1, 0, 0, 0, 23, 0, 0, 0, 200, 1, 0, 0, 210, 30, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0,
];
rand::rngs::StdRng::from_seed(seed)
}
#[cfg(not(feature = "std"))]
pub fn test_rng() -> impl rand::Rng {
test_rng_helper()
}
#[cfg(feature = "std")]
pub fn test_rng() -> impl rand::Rng {
#[cfg(any(feature = "getrandom", test))]
{
let is_deterministic =
std::env::vars().any(|(key, val)| key == "DETERMINISTIC_TEST_RNG" && val == "1");
if is_deterministic {
RngWrapper::Deterministic(test_rng_helper())
} else {
RngWrapper::Randomized(rand::thread_rng())
}
}
#[cfg(not(any(feature = "getrandom", test)))]
{
RngWrapper::Deterministic(test_rng_helper())
}
}
#[cfg(feature = "std")]
enum RngWrapper {
Deterministic(StdRng),
#[cfg(any(feature = "getrandom", test))]
Randomized(rand::rngs::ThreadRng),
}
#[cfg(feature = "std")]
impl RngCore for RngWrapper {
#[inline(always)]
fn next_u32(&mut self) -> u32 {
match self {
Self::Deterministic(rng) => rng.next_u32(),
#[cfg(any(feature = "getrandom", test))]
Self::Randomized(rng) => rng.next_u32(),
}
}
#[inline(always)]
fn next_u64(&mut self) -> u64 {
match self {
Self::Deterministic(rng) => rng.next_u64(),
#[cfg(any(feature = "getrandom", test))]
Self::Randomized(rng) => rng.next_u64(),
}
}
#[inline(always)]
fn fill_bytes(&mut self, dest: &mut [u8]) {
match self {
Self::Deterministic(rng) => rng.fill_bytes(dest),
#[cfg(any(feature = "getrandom", test))]
Self::Randomized(rng) => rng.fill_bytes(dest),
}
}
#[inline(always)]
fn try_fill_bytes(&mut self, dest: &mut [u8]) -> Result<(), rand::Error> {
match self {
Self::Deterministic(rng) => rng.try_fill_bytes(dest),
#[cfg(any(feature = "getrandom", test))]
Self::Randomized(rng) => rng.try_fill_bytes(dest),
}
}
}
#[cfg(all(test, feature = "std"))]
mod test {
#[test]
fn test_deterministic_rng() {
use super::*;
let mut rng = super::test_rng();
let a = u128::rand(&mut rng);
let mut rng = super::test_rng();
let b = u128::rand(&mut rng);
assert_ne!(a, b); std::env::set_var("DETERMINISTIC_TEST_RNG", "1");
let mut rng = super::test_rng();
let a = u128::rand(&mut rng);
let mut rng = super::test_rng();
let b = u128::rand(&mut rng);
assert_eq!(a, b); }
}