dashu-int 0.6.0

Arbitrary-precision integer math library for Rust, balancing ergonomics and efficiency. Provides UBig and IBig (unsigned and signed), with small values inlined on the stack. Efficient arithmetic, modular arithmetic, and number theory (pow, ilog, gcd, gcd_ext); two's-complement bit operations; parsing and formatting in base 2-36; optional serde, rand, num-traits, rkyv, and zeroize.
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use crate::{
    arch::word::{DoubleWord, Word},
    ibig::IBig,
    ops::UnsignedAbs,
    ubig::UBig,
};
use rand_v010::{
    distr::uniform::{Error, SampleBorrow, SampleUniform, UniformSampler},
    distr::Distribution,
    Rng, RngExt,
};

use super::rand::*;

/// Adapter exposing a rand 0.10 [`Rng`] as a [`BitRng`].
pub struct RngBridge<'a, R: Rng + ?Sized>(pub &'a mut R);

impl<'a, R: Rng + ?Sized> BitRng for RngBridge<'a, R> {
    #[inline]
    fn next_word(&mut self) -> Word {
        self.0.random()
    }
    #[inline]
    fn next_double_word(&mut self) -> DoubleWord {
        self.0.random()
    }
    #[inline]
    fn next_bool(&mut self) -> bool {
        self.0.random()
    }
    #[inline]
    fn fill_words(&mut self, words: &mut [Word]) {
        self.0.fill(words)
    }
    #[inline]
    fn gen_word_inclusive(&mut self, high: Word) -> Word {
        self.0.random_range(0..=high)
    }
    #[inline]
    fn gen_dword_exclusive(&mut self, high: DoubleWord) -> DoubleWord {
        self.0.random_range(0..high)
    }
}

fn bridge<R: Rng + ?Sized>(rng: &mut R) -> RngBridge<'_, R> {
    RngBridge(rng)
}

impl Distribution<UBig> for UniformBits {
    #[inline]
    fn sample<R: Rng + ?Sized>(&self, rng: &mut R) -> UBig {
        self.sample_ubig(&mut bridge(rng))
    }
}

impl Distribution<IBig> for UniformBits {
    #[inline]
    fn sample<R: Rng + ?Sized>(&self, rng: &mut R) -> IBig {
        self.sample_ibig(&mut bridge(rng))
    }
}

impl Distribution<UBig> for UniformBelow<'_> {
    #[inline]
    fn sample<R: Rng + ?Sized>(&self, rng: &mut R) -> UBig {
        self.sample_ubig(&mut bridge(rng))
    }
}

impl Distribution<IBig> for UniformBelow<'_> {
    #[inline]
    fn sample<R: Rng + ?Sized>(&self, rng: &mut R) -> IBig {
        self.sample_ibig(&mut bridge(rng))
    }
}

impl UniformSampler for UniformUBig {
    type X = UBig;

    #[inline]
    fn new<B1, B2>(low: B1, high: B2) -> Result<UniformUBig, Error>
    where
        B1: SampleBorrow<UBig> + Sized,
        B2: SampleBorrow<UBig> + Sized,
    {
        if high.borrow() <= low.borrow() {
            return Err(Error::EmptyRange);
        }
        let range = high.borrow() - low.borrow();
        Ok(UniformUBig::from_parts(range, low.borrow().clone()))
    }

    #[inline]
    fn new_inclusive<B1, B2>(low: B1, high: B2) -> Result<UniformUBig, Error>
    where
        B1: SampleBorrow<UBig> + Sized,
        B2: SampleBorrow<UBig> + Sized,
    {
        if high.borrow() < low.borrow() {
            return Err(Error::EmptyRange);
        }
        let range = high.borrow() - low.borrow() + UBig::ONE;
        Ok(UniformUBig::from_parts(range, low.borrow().clone()))
    }

    #[inline]
    fn sample<R: Rng + ?Sized>(&self, rng: &mut R) -> UBig {
        let mut b = bridge(rng);
        UniformUBig::sample(self, &mut b)
    }
}

impl UniformSampler for UniformIBig {
    type X = IBig;

    #[inline]
    fn new<B1, B2>(low: B1, high: B2) -> Result<UniformIBig, Error>
    where
        B1: SampleBorrow<IBig> + Sized,
        B2: SampleBorrow<IBig> + Sized,
    {
        if high.borrow() <= low.borrow() {
            return Err(Error::EmptyRange);
        }
        let range = high.borrow() - low.borrow();
        Ok(UniformIBig::from_parts(range.unsigned_abs(), low.borrow().clone()))
    }

    #[inline]
    fn new_inclusive<B1, B2>(low: B1, high: B2) -> Result<UniformIBig, Error>
    where
        B1: SampleBorrow<IBig> + Sized,
        B2: SampleBorrow<IBig> + Sized,
    {
        if high.borrow() < low.borrow() {
            return Err(Error::EmptyRange);
        }
        let range = high.borrow() - low.borrow() + IBig::ONE;
        Ok(UniformIBig::from_parts(range.unsigned_abs(), low.borrow().clone()))
    }

    #[inline]
    fn sample<R: Rng + ?Sized>(&self, rng: &mut R) -> IBig {
        let mut b = bridge(rng);
        UniformIBig::sample(self, &mut b)
    }
}

impl SampleUniform for UBig {
    type Sampler = UniformUBig;
}

impl SampleUniform for IBig {
    type Sampler = UniformIBig;
}