num_traits/
bounds.rs

1use core::num::Wrapping;
2use core::{f32, f64};
3#[cfg(has_i128)]
4use core::{i128, u128};
5use core::{i16, i32, i64, i8, isize};
6use core::{u16, u32, u64, u8, usize};
7
8/// Numbers which have upper and lower bounds
9pub trait Bounded {
10    // FIXME (#5527): These should be associated constants
11    /// Returns the smallest finite number this type can represent
12    fn min_value() -> Self;
13    /// Returns the largest finite number this type can represent
14    fn max_value() -> Self;
15}
16
17/// Numbers which have lower bounds
18pub trait LowerBounded {
19    /// Returns the smallest finite number this type can represent
20    fn min_value() -> Self;
21}
22
23// FIXME: With a major version bump, this should be a supertrait instead
24impl<T: Bounded> LowerBounded for T {
25    fn min_value() -> T {
26        Bounded::min_value()
27    }
28}
29
30/// Numbers which have upper bounds
31pub trait UpperBounded {
32    /// Returns the largest finite number this type can represent
33    fn max_value() -> Self;
34}
35
36// FIXME: With a major version bump, this should be a supertrait instead
37impl<T: Bounded> UpperBounded for T {
38    fn max_value() -> T {
39        Bounded::max_value()
40    }
41}
42
43macro_rules! bounded_impl {
44    ($t:ty, $min:expr, $max:expr) => {
45        impl Bounded for $t {
46            #[inline]
47            fn min_value() -> $t {
48                $min
49            }
50
51            #[inline]
52            fn max_value() -> $t {
53                $max
54            }
55        }
56    };
57}
58
59bounded_impl!(usize, usize::MIN, usize::MAX);
60bounded_impl!(u8, u8::MIN, u8::MAX);
61bounded_impl!(u16, u16::MIN, u16::MAX);
62bounded_impl!(u32, u32::MIN, u32::MAX);
63bounded_impl!(u64, u64::MIN, u64::MAX);
64#[cfg(has_i128)]
65bounded_impl!(u128, u128::MIN, u128::MAX);
66
67bounded_impl!(isize, isize::MIN, isize::MAX);
68bounded_impl!(i8, i8::MIN, i8::MAX);
69bounded_impl!(i16, i16::MIN, i16::MAX);
70bounded_impl!(i32, i32::MIN, i32::MAX);
71bounded_impl!(i64, i64::MIN, i64::MAX);
72#[cfg(has_i128)]
73bounded_impl!(i128, i128::MIN, i128::MAX);
74
75impl<T: Bounded> Bounded for Wrapping<T> {
76    fn min_value() -> Self {
77        Wrapping(T::min_value())
78    }
79    fn max_value() -> Self {
80        Wrapping(T::max_value())
81    }
82}
83
84bounded_impl!(f32, f32::MIN, f32::MAX);
85
86macro_rules! for_each_tuple_ {
87    ( $m:ident !! ) => (
88        $m! { }
89    );
90    ( $m:ident !! $h:ident, $($t:ident,)* ) => (
91        $m! { $h $($t)* }
92        for_each_tuple_! { $m !! $($t,)* }
93    );
94}
95macro_rules! for_each_tuple {
96    ($m:ident) => {
97        for_each_tuple_! { $m !! A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P, Q, R, S, T, }
98    };
99}
100
101macro_rules! bounded_tuple {
102    ( $($name:ident)* ) => (
103        impl<$($name: Bounded,)*> Bounded for ($($name,)*) {
104            #[inline]
105            fn min_value() -> Self {
106                ($($name::min_value(),)*)
107            }
108            #[inline]
109            fn max_value() -> Self {
110                ($($name::max_value(),)*)
111            }
112        }
113    );
114}
115
116for_each_tuple!(bounded_tuple);
117bounded_impl!(f64, f64::MIN, f64::MAX);
118
119#[test]
120fn wrapping_bounded() {
121    macro_rules! test_wrapping_bounded {
122        ($($t:ty)+) => {
123            $(
124                assert_eq!(<Wrapping<$t> as Bounded>::min_value().0, <$t>::min_value());
125                assert_eq!(<Wrapping<$t> as Bounded>::max_value().0, <$t>::max_value());
126            )+
127        };
128    }
129
130    test_wrapping_bounded!(usize u8 u16 u32 u64 isize i8 i16 i32 i64);
131}
132
133#[cfg(has_i128)]
134#[test]
135fn wrapping_bounded_i128() {
136    macro_rules! test_wrapping_bounded {
137        ($($t:ty)+) => {
138            $(
139                assert_eq!(<Wrapping<$t> as Bounded>::min_value().0, <$t>::min_value());
140                assert_eq!(<Wrapping<$t> as Bounded>::max_value().0, <$t>::max_value());
141            )+
142        };
143    }
144
145    test_wrapping_bounded!(u128 i128);
146}
147
148#[test]
149fn wrapping_is_bounded() {
150    fn require_bounded<T: Bounded>(_: &T) {}
151    require_bounded(&Wrapping(42_u32));
152    require_bounded(&Wrapping(-42));
153}
num_traits/bounds.rs

num_traits/
bounds.rs
