malachite_nz/integer/arithmetic/is_unit.rs
1// Copyright © 2026 Mikhail Hogrefe
2//
3// This file is part of Malachite.
4//
5// Malachite is free software: you can redistribute it and/or modify it under the terms of the GNU
6// Lesser General Public License (LGPL) as published by the Free Software Foundation; either version
7// 3 of the License, or (at your option) any later version. See <https://www.gnu.org/licenses/>.
8
9use crate::integer::Integer;
10use malachite_base::num::arithmetic::traits::IsUnit;
11
12impl IsUnit for Integer {
13 /// Determines whether a [`Integer`] is a unit: whether it is 1 or $-1$, the only integers with
14 /// a multiplicative inverse.
15 ///
16 /// # Worst-case complexity
17 /// Constant time and additional memory.
18 ///
19 /// # Examples
20 /// ```
21 /// use malachite_base::num::arithmetic::traits::IsUnit;
22 /// use malachite_base::num::basic::traits::{NegativeOne, One, Zero};
23 /// use malachite_nz::integer::Integer;
24 ///
25 /// assert_eq!(Integer::ONE.is_unit(), true);
26 /// assert_eq!(Integer::NEGATIVE_ONE.is_unit(), true);
27 /// assert_eq!(Integer::ZERO.is_unit(), false);
28 /// assert_eq!(Integer::from(-123).is_unit(), false);
29 /// ```
30 #[inline]
31 fn is_unit(&self) -> bool {
32 self.abs == 1u32
33 }
34}