1//! Types for dealing with rational numbers.
2use core::ops::{Add, Div, Mul};
3
4use num_traits::{CheckedAdd, CheckedDiv, CheckedMul};
5
6/// Represents the ratio between two numbers.
7#[derive(Copy, Clone, Debug)]
8#[cfg_attr(feature = "defmt", derive(defmt::Format))]
9pub struct Ratio<T> {
10 /// Numerator.
11 numer: T,
12 /// Denominator.
13 denom: T,
14}
15
16impl<T> Ratio<T> {
17 /// Creates a new `Ratio`.
18 #[inline(always)]
19 pub const fn new_raw(numer: T, denom: T) -> Ratio<T> {
20 Ratio { numer, denom }
21 }
22
23 /// Gets an immutable reference to the numerator.
24 #[inline(always)]
25 pub const fn numer(&self) -> &T {
26 &self.numer
27 }
28
29 /// Gets an immutable reference to the denominator.
30 #[inline(always)]
31 pub const fn denom(&self) -> &T {
32 &self.denom
33 }
34}
35
36impl<T: CheckedDiv> Ratio<T> {
37 /// Converts to an integer, rounding towards zero.
38 #[inline(always)]
39 pub fn to_integer(&self) -> T {
40 unwrap!(self.numer().checked_div(self.denom()))
41 }
42}
43
44impl<T: CheckedMul> Div<T> for Ratio<T> {
45 type Output = Self;
46
47 #[inline(always)]
48 fn div(mut self, rhs: T) -> Self::Output {
49 self.denom = unwrap!(self.denom().checked_mul(&rhs));
50 self
51 }
52}
53
54impl<T: CheckedMul> Mul<T> for Ratio<T> {
55 type Output = Self;
56
57 #[inline(always)]
58 fn mul(mut self, rhs: T) -> Self::Output {
59 self.numer = unwrap!(self.numer().checked_mul(&rhs));
60 self
61 }
62}
63
64impl<T: CheckedMul + CheckedAdd> Add<T> for Ratio<T> {
65 type Output = Self;
66
67 #[inline(always)]
68 fn add(mut self, rhs: T) -> Self::Output {
69 self.numer = unwrap!(unwrap!(self.denom().checked_mul(&rhs)).checked_add(self.numer()));
70 self
71 }
72}
73
74macro_rules! impl_from_for_float {
75 ($from:ident) => {
76 impl From<Ratio<$from>> for f32 {
77 #[inline(always)]
78 fn from(r: Ratio<$from>) -> Self {
79 (r.numer as f32) / (r.denom as f32)
80 }
81 }
82
83 impl From<Ratio<$from>> for f64 {
84 #[inline(always)]
85 fn from(r: Ratio<$from>) -> Self {
86 (r.numer as f64) / (r.denom as f64)
87 }
88 }
89 };
90}
91
92impl_from_for_float!(u8);
93impl_from_for_float!(u16);
94impl_from_for_float!(u32);
95impl_from_for_float!(u64);
96impl_from_for_float!(u128);
97impl_from_for_float!(i8);
98impl_from_for_float!(i16);
99impl_from_for_float!(i32);
100impl_from_for_float!(i64);
101impl_from_for_float!(i128);
102
103impl<T: core::fmt::Display> core::fmt::Display for Ratio<T> {
104 fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
105 core::write!(f, "{} / {}", self.numer(), self.denom())
106 }
107}
108
109#[cfg(test)]
110mod tests {
111 use super::Ratio;
112
113 #[test]
114 fn basics() {
115 let mut r = Ratio::new_raw(1, 2) + 2;
116 assert_eq!(*r.numer(), 5);
117 assert_eq!(*r.denom(), 2);
118 assert_eq!(r.to_integer(), 2);
119
120 r = r * 2;
121 assert_eq!(*r.numer(), 10);
122 assert_eq!(*r.denom(), 2);
123 assert_eq!(r.to_integer(), 5);
124
125 r = r / 2;
126 assert_eq!(*r.numer(), 10);
127 assert_eq!(*r.denom(), 4);
128 assert_eq!(r.to_integer(), 2);
129 }
130}
131