malachite_nz/natural/comparison/
partial_cmp_primitive_float.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::natural::Natural;
10use core::cmp::Ordering::{self, *};
11use malachite_base::num::conversion::traits::{ExactFrom, IntegerMantissaAndExponent};
12use malachite_base::num::logic::traits::SignificantBits;
13
14macro_rules! impl_float {
15    ($t: ident) => {
16        impl PartialOrd<$t> for Natural {
17            /// Compares a [`Natural`] to a primitive float.
18            ///
19            /// # Worst-case complexity
20            /// $T(n) = O(n)$
21            ///
22            /// $M(n) = O(1)$
23            ///
24            /// where $T$ is time, $M$ is additional memory, and $n$ is `self.significant_bits()`.
25            ///
26            /// See [here](super::partial_cmp_primitive_float#partial_cmp).
27            fn partial_cmp(&self, other: &$t) -> Option<Ordering> {
28                if other.is_nan() {
29                    None
30                } else if *other < 0.0 {
31                    Some(Greater)
32                } else if !other.is_finite() {
33                    Some(Less)
34                } else if *other == 0.0 {
35                    self.partial_cmp(&0u32)
36                } else if *self == 0u32 {
37                    Some(Less)
38                } else {
39                    let (m, e) = other.integer_mantissa_and_exponent();
40                    let log_cmp = i64::exact_from(self.significant_bits())
41                        .cmp(&(i64::exact_from(m.significant_bits()) + e));
42                    Some(if log_cmp != Equal {
43                        log_cmp
44                    } else {
45                        self.cmp_normalized(&Natural::from(m))
46                    })
47                }
48            }
49        }
50
51        impl PartialOrd<Natural> for $t {
52            /// Compares a primitive float to a [`Natural`].
53            ///
54            /// # Worst-case complexity
55            /// $T(n) = O(n)$
56            ///
57            /// $M(n) = O(1)$
58            ///
59            /// where $T$ is time, $M$ is additional memory, and $n$ is `other.significant_bits()`.
60            ///
61            /// See [here](super::partial_cmp_primitive_float#partial_cmp).
62            #[inline]
63            fn partial_cmp(&self, other: &Natural) -> Option<Ordering> {
64                other.partial_cmp(self).map(Ordering::reverse)
65            }
66        }
67    };
68}
69apply_to_primitive_floats!(impl_float);
malachite_nz/natural/comparison/partial_cmp_primitive_float.rs

malachite_nz/natural/comparison/
partial_cmp_primitive_float.rs
