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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::num::arithmetic::traits::{ModPowerOf2IsReduced, ModPowerOf2Mul, ModPowerOf2MulAssign};
use crate::num::basic::unsigneds::PrimitiveUnsigned;
use crate::unsigned_vector::UnsignedVector;
fn assert_reduced<T: PrimitiveUnsigned>(v: &UnsignedVector<T>, c: T, pow: u64) {
assert!(
pow <= T::WIDTH,
"pow must be at most T::WIDTH, but it is {pow}"
);
assert!(
v.mod_power_of_2_is_reduced(pow),
"self must be reduced mod 2^pow, but {v} has an element >= 2^{pow}"
);
assert!(
c.mod_power_of_2_is_reduced(pow),
"c must be reduced mod 2^pow, but {c} >= 2^{pow}"
);
}
impl<T: PrimitiveUnsigned> ModPowerOf2Mul<T> for UnsignedVector<T> {
type Output = Self;
/// Multiplies every element of an [`UnsignedVector`] by a scalar modulo $2^k$, taking the
/// vector by value. The elements and the scalar must already be reduced modulo $2^k$.
///
/// Each product is reduced modulo $2^k$, and the result has the same dimension as the vector.
///
/// $$
/// f(v, c, k) = cv \bmod 2^k.
/// $$
///
/// # Worst-case complexity
/// $T(n) = O(n)$
///
/// $M(n) = O(1)$
///
/// where $T$ is time, $M$ is additional memory, and $n$ is `self.dimension()`.
///
/// # Panics
/// Panics if `pow` is greater than `T::WIDTH`, or if any element of `self`, or `c`, is greater
/// than or equal to $2^k$.
///
/// # Examples
/// ```
/// use core::str::FromStr;
/// use malachite_base::num::arithmetic::traits::ModPowerOf2Mul;
/// use malachite_base::unsigned_vector::UnsignedVector;
///
/// let v = UnsignedVector::<u8>::from_str("(5, 1, 3)").unwrap();
/// assert_eq!(v.mod_power_of_2_mul(3, 3).to_string(), "(7, 3, 1)");
/// ```
#[inline]
fn mod_power_of_2_mul(mut self, c: T, pow: u64) -> Self {
self.mod_power_of_2_mul_assign(c, pow);
self
}
}
impl<T: PrimitiveUnsigned> ModPowerOf2Mul<T> for &UnsignedVector<T> {
type Output = UnsignedVector<T>;
/// Multiplies every element of an [`UnsignedVector`] by a scalar modulo $2^k$, taking the
/// vector by reference. The elements and the scalar must already be reduced modulo $2^k$.
///
/// See the documentation for the [`ModPowerOf2Mul`] implementation that takes the vector by
/// value for details.
///
/// # Worst-case complexity
/// $T(n) = O(n)$
///
/// $M(n) = O(n)$
///
/// where $T$ is time, $M$ is additional memory, and $n$ is `self.dimension()`.
///
/// # Panics
/// Panics if `pow` is greater than `T::WIDTH`, or if any element of `self`, or `c`, is greater
/// than or equal to $2^k$.
///
/// # Examples
/// ```
/// use core::str::FromStr;
/// use malachite_base::num::arithmetic::traits::ModPowerOf2Mul;
/// use malachite_base::unsigned_vector::UnsignedVector;
///
/// let v = UnsignedVector::<u8>::from_str("(5, 1, 3)").unwrap();
/// assert_eq!((&v).mod_power_of_2_mul(3, 3).to_string(), "(7, 3, 1)");
/// ```
fn mod_power_of_2_mul(self, c: T, pow: u64) -> UnsignedVector<T> {
assert_reduced(self, c, pow);
UnsignedVector {
elements: self
.elements
.iter()
.map(|&x| x.mod_power_of_2_mul(c, pow))
.collect(),
}
}
}
impl<T: PrimitiveUnsigned> ModPowerOf2MulAssign<T> for UnsignedVector<T> {
/// Multiplies every element of an [`UnsignedVector`] by a scalar modulo $2^k$, in place. The
/// elements and the scalar must already be reduced modulo $2^k$.
///
/// See the documentation for the [`ModPowerOf2Mul`] implementation that takes the vector by
/// value for details.
///
/// # Worst-case complexity
/// $T(n) = O(n)$
///
/// $M(n) = O(1)$
///
/// where $T$ is time, $M$ is additional memory, and $n$ is `self.dimension()`.
///
/// # Panics
/// Panics if `pow` is greater than `T::WIDTH`, or if any element of `self`, or `c`, is greater
/// than or equal to $2^k$.
///
/// # Examples
/// ```
/// use core::str::FromStr;
/// use malachite_base::num::arithmetic::traits::ModPowerOf2MulAssign;
/// use malachite_base::unsigned_vector::UnsignedVector;
///
/// let mut v = UnsignedVector::<u8>::from_str("(5, 1, 3)").unwrap();
/// v.mod_power_of_2_mul_assign(3, 3);
/// assert_eq!(v.to_string(), "(7, 3, 1)");
/// ```
fn mod_power_of_2_mul_assign(&mut self, c: T, pow: u64) {
assert_reduced(self, c, pow);
for x in &mut self.elements {
x.mod_power_of_2_mul_assign(c, pow);
}
}
}