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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::DivisibleBy;
use crate::num::basic::signeds::PrimitiveSigned;
use crate::num::basic::unsigneds::PrimitiveUnsigned;
fn divisible_by_unsigned<T: PrimitiveUnsigned>(x: T, other: T) -> bool {
x == T::ZERO || other != T::ZERO && x % other == T::ZERO
}
macro_rules! impl_divisible_by_unsigned {
($t:ident) => {
impl DivisibleBy<$t> for $t {
/// Returns whether a number is divisible by another number; in other words, whether the
/// first number is a multiple of the second.
///
/// This means that zero is divisible by any number, including zero; but a nonzero
/// number is never divisible by zero.
///
/// $f(x, m) = (m|x)$.
///
/// $f(x, m) = (\exists k \in \N : x = km)$.
///
/// # Worst-case complexity
/// Constant time and additional memory.
///
/// # Examples
/// See [here](super::divisible_by#divisible_by).
#[inline]
fn divisible_by(self, other: $t) -> bool {
divisible_by_unsigned(self, other)
}
}
};
}
apply_to_unsigneds!(impl_divisible_by_unsigned);
fn divisible_by_signed<T: PrimitiveSigned>(x: T, other: T) -> bool {
x == T::ZERO
|| x == T::MIN && other == T::NEGATIVE_ONE
|| other != T::ZERO && x % other == T::ZERO
}
macro_rules! impl_divisible_by_signed {
($t:ident) => {
impl DivisibleBy<$t> for $t {
/// Returns whether a number is divisible by another number; in other words, whether the
/// first number is a multiple of the second.
///
/// This means that zero is divisible by any number, including zero; but a nonzero
/// number is never divisible by zero.
///
/// $f(x, m) = (m|x)$.
///
/// $f(x, m) = (\exists k \in \Z : \ x = km)$.
///
/// # Worst-case complexity
/// Constant time and additional memory.
///
/// # Examples
/// See [here](super::divisible_by#divisible_by).
#[inline]
fn divisible_by(self, other: $t) -> bool {
divisible_by_signed(self, other)
}
}
};
}
apply_to_signeds!(impl_divisible_by_signed);