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// Copyright © 2026 Mikhail Hogrefe
//
// This file is part of Malachite.
//
// Malachite is free software: you can redistribute it and/or modify it under the terms of the GNU
// Lesser General Public License (LGPL) as published by the Free Software Foundation; either version
// 3 of the License, or (at your option) any later version. See <https://www.gnu.org/licenses/>.
use crate::rational_vector::RationalVector;
use malachite_base::num::arithmetic::traits::{
CanonicalizeSign, CanonicalizeSignAssign, NegAssign,
};
use malachite_base::vector::Vector;
impl CanonicalizeSign for RationalVector {
type Output = Self;
/// Brings a [`RationalVector`] into canonical sign form, taking the vector by value: negates it
/// if its pivot, its first nonzero element, is negative.
///
/// A vector and its negation are the same up to multiplication by $\pm 1$, the units of the
/// integers acting on it, and this picks the one whose pivot is positive to represent both. A
/// vector of zeros has no pivot and is left alone.
///
/// # Worst-case complexity
/// $T(n) = O(n)$
///
/// $M(n) = O(1)$
///
/// where $T$ is time, $M$ is additional memory, and $n$ is `self.dimension()`.
///
/// # Examples
/// ```
/// use core::str::FromStr;
/// use malachite_base::num::arithmetic::traits::CanonicalizeSign;
/// use malachite_q::rational_vector::RationalVector;
///
/// let v = RationalVector::from_str("(0, -2/3, 3)").unwrap();
/// assert_eq!(v.canonicalize_sign().to_string(), "(0, 2/3, -3)");
/// let v = RationalVector::from_str("(0, 2/3, -3)").unwrap();
/// assert_eq!(v.canonicalize_sign().to_string(), "(0, 2/3, -3)");
/// ```
#[inline]
fn canonicalize_sign(mut self) -> Self {
self.canonicalize_sign_assign();
self
}
}
impl CanonicalizeSign for &RationalVector {
type Output = RationalVector;
/// Brings a [`RationalVector`] into canonical sign form, taking the vector by reference:
/// negates it if its pivot, its first nonzero element, is negative.
///
/// See the documentation for the [`CanonicalizeSign`] implementation on [`RationalVector`].
///
/// # Worst-case complexity
/// $T(n) = O(n)$
///
/// $M(n) = O(n)$
///
/// where $T$ is time, $M$ is additional memory, and $n$ is the total number of bits of the
/// elements.
///
/// # Examples
/// ```
/// use core::str::FromStr;
/// use malachite_base::num::arithmetic::traits::CanonicalizeSign;
/// use malachite_q::rational_vector::RationalVector;
///
/// let v = RationalVector::from_str("(0, -2/3, 3)").unwrap();
/// assert_eq!((&v).canonicalize_sign().to_string(), "(0, 2/3, -3)");
/// ```
#[inline]
fn canonicalize_sign(self) -> RationalVector {
if self.pivot().is_some_and(|x| *x < 0u32) {
-self
} else {
self.clone()
}
}
}
impl CanonicalizeSignAssign for RationalVector {
/// Replaces a [`RationalVector`] with its canonical sign form: negates it if its pivot, its
/// first nonzero element, is negative.
///
/// See the documentation for the [`CanonicalizeSign`] implementation on [`RationalVector`].
///
/// # Worst-case complexity
/// $T(n) = O(n)$
///
/// $M(n) = O(1)$
///
/// where $T$ is time, $M$ is additional memory, and $n$ is `self.dimension()`.
///
/// # Examples
/// ```
/// use core::str::FromStr;
/// use malachite_base::num::arithmetic::traits::CanonicalizeSignAssign;
/// use malachite_q::rational_vector::RationalVector;
///
/// let mut v = RationalVector::from_str("(0, -2/3, 3)").unwrap();
/// v.canonicalize_sign_assign();
/// assert_eq!(v.to_string(), "(0, 2/3, -3)");
/// ```
#[inline]
fn canonicalize_sign_assign(&mut self) {
if self.pivot().is_some_and(|x| *x < 0u32) {
self.neg_assign();
}
}
}