dashu-int 0.6.0-rc.4

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.
Documentation 
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//! Comparisons operators.

use dashu_base::AbsOrd;

use crate::{
    arch::word::Word,
    ibig::IBig,
    repr::TypedReprRef::{self, *},
    ubig::UBig,
    Sign::*,
};
use core::cmp::Ordering;

/// Compare lhs with rhs of the same length as numbers.
#[inline]
pub fn cmp_same_len(lhs: &[Word], rhs: &[Word]) -> Ordering {
    debug_assert!(lhs.len() == rhs.len());
    lhs.iter().rev().cmp(rhs.iter().rev())
}

/// Compare lhs with rhs as numbers. The leading zero words of the input must be trimmed.
///
/// # Panics
///
/// Panic if lhs or rhs has leading zero words (including the case where lhs == 0 or rhs == 0)
pub fn cmp_in_place(lhs: &[Word], rhs: &[Word]) -> Ordering {
    debug_assert!(*lhs.last().unwrap() != 0 && *rhs.last().unwrap() != 0);
    lhs.len()
        .cmp(&rhs.len())
        .then_with(|| cmp_same_len(lhs, rhs))
}

impl<'a> PartialOrd for TypedReprRef<'a> {
    #[inline]
    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
        Some(self.cmp(other))
    }
}

impl<'a> Ord for TypedReprRef<'a> {
    #[inline]
    fn cmp(&self, other: &Self) -> Ordering {
        match (*self, *other) {
            (RefSmall(dword0), RefSmall(dword1)) => dword0.cmp(&dword1),
            (RefSmall(_), RefLarge(_)) => Ordering::Less,
            (RefLarge(_), RefSmall(_)) => Ordering::Greater,
            (RefLarge(words0), RefLarge(words1)) => cmp_in_place(words0, words1),
        }
    }
}

impl Ord for UBig {
    #[inline]
    fn cmp(&self, other: &UBig) -> Ordering {
        self.repr().cmp(&other.repr())
    }
}

impl PartialOrd for UBig {
    #[inline]
    fn partial_cmp(&self, other: &UBig) -> Option<Ordering> {
        Some(self.cmp(other))
    }
}

impl Ord for IBig {
    #[inline]
    fn cmp(&self, other: &IBig) -> Ordering {
        let (lhs_sign, lhs_mag) = self.as_sign_repr();
        let (rhs_sign, rhs_mag) = other.as_sign_repr();
        match (lhs_sign, rhs_sign) {
            (Positive, Positive) => lhs_mag.cmp(&rhs_mag),
            (Positive, Negative) => Ordering::Greater,
            (Negative, Positive) => Ordering::Less,
            (Negative, Negative) => rhs_mag.cmp(&lhs_mag),
        }
    }
}

impl PartialOrd for IBig {
    #[inline]
    fn partial_cmp(&self, other: &IBig) -> Option<Ordering> {
        Some(self.cmp(other))
    }
}

impl AbsOrd for UBig {
    #[inline]
    fn abs_cmp(&self, rhs: &Self) -> Ordering {
        self.0.as_typed().cmp(&rhs.0.as_typed())
    }
}
impl AbsOrd for IBig {
    #[inline]
    fn abs_cmp(&self, rhs: &Self) -> Ordering {
        self.0.as_sign_typed().1.cmp(&rhs.0.as_sign_typed().1)
    }
}
impl AbsOrd<UBig> for IBig {
    #[inline]
    fn abs_cmp(&self, rhs: &UBig) -> Ordering {
        self.0.as_sign_typed().1.cmp(&rhs.0.as_typed())
    }
}
impl AbsOrd<IBig> for UBig {
    #[inline]
    fn abs_cmp(&self, rhs: &IBig) -> Ordering {
        self.0.as_typed().cmp(&rhs.0.as_sign_typed().1)
    }
}