malachite_float/comparison/
partial_cmp_primitive_float.rs

1// Copyright © 2025 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::Float;
10use crate::InnerFloat::{Finite, Infinity, NaN, Zero};
11use core::cmp::Ordering::{self, *};
12use malachite_base::num::arithmetic::traits::Sign;
13use malachite_base::num::basic::floats::PrimitiveFloat;
14use malachite_nz::natural::Natural;
15
16fn float_partial_cmp_primitive_float<T: PrimitiveFloat>(x: &Float, y: &T) -> Option<Ordering> {
17    match (x, y) {
18        (float_nan!(), _) => None,
19        (_, y) if y.is_nan() => None,
20        (float_infinity!(), y) if *y == T::INFINITY => Some(Equal),
21        (float_negative_infinity!(), y) if *y == T::NEGATIVE_INFINITY => Some(Equal),
22        (float_infinity!(), _) => Some(Greater),
23        (float_negative_infinity!(), _) => Some(Less),
24        (_, y) if *y == T::NEGATIVE_INFINITY => Some(Greater),
25        (_, y) if *y == T::INFINITY => Some(Less),
26        (float_either_zero!(), y) => Some(if *y == T::ZERO {
27            Equal
28        } else if y.is_sign_positive() {
29            Less
30        } else {
31            Greater
32        }),
33        (x, y) if *y == T::ZERO => Some(x.sign()),
34        (
35            Float(Finite {
36                sign: s_x,
37                exponent: e_x,
38                significand: m_x,
39                ..
40            }),
41            y,
42        ) => {
43            let s_y = y.is_sign_positive();
44            Some(s_x.cmp(&s_y).then_with(|| {
45                let abs_cmp = (i64::from(*e_x) - 1)
46                    .cmp(&y.sci_exponent())
47                    .then_with(|| m_x.cmp_normalized(&Natural::from(y.integer_mantissa())));
48                if *s_x { abs_cmp } else { abs_cmp.reverse() }
49            }))
50        }
51    }
52}
53
54macro_rules! impl_partial_cmp_primitive_float {
55    ($t: ident) => {
56        impl PartialOrd<$t> for Float {
57            /// Compares a [`Float`] to a primitive float.
58            ///
59            /// The [`Float`] NaN is not comparable to any primitive float, not even the primitive
60            /// float NaN. Every [`Float`] zero is equal to every primitive float zero, regardless
61            /// of sign.
62            ///
63            /// # Worst-case complexity
64            /// $T(n) = O(n)$
65            ///
66            /// $M(n) = O(1)$
67            ///
68            /// where $T$ is time, $M$ is additional memory, and $n$ is
69            /// `max(self.significant_bits(), other.sci_exponent().abs())`.
70            ///
71            /// # Examples
72            /// See [here](super::partial_cmp_primitive_float#partial_cmp).
73            #[inline]
74            fn partial_cmp(&self, other: &$t) -> Option<Ordering> {
75                float_partial_cmp_primitive_float(self, other)
76            }
77        }
78
79        impl PartialOrd<Float> for $t {
80            /// Compares a primitive float to a [`Float`].
81            ///
82            /// The primitive float NaN is not comparable to any primitive float, not even the
83            /// [`Float`] NaN. Every primitive float zero is equal to every [`Float`] zero,
84            /// regardless of sign.
85            ///
86            /// # Worst-case complexity
87            /// $T(n) = O(n)$
88            ///
89            /// $M(n) = O(1)$
90            ///
91            /// where $T$ is time, $M$ is additional memory, and $n$ is
92            /// `max(self.significant_bits(), other.sci_exponent().abs())`.
93            ///
94            /// # Examples
95            /// See [here](super::partial_cmp_primitive_float#partial_cmp).
96            #[inline]
97            fn partial_cmp(&self, other: &Float) -> Option<Ordering> {
98                other.partial_cmp(self).map(Ordering::reverse)
99            }
100        }
101    };
102}
103apply_to_primitive_floats!(impl_partial_cmp_primitive_float);
malachite_float/comparison/partial_cmp_primitive_float.rs

malachite_float/comparison/
partial_cmp_primitive_float.rs
