1 use core::num::Wrapping;
2 use core::{f32, f64};
3 use core::{i128, i16, i32, i64, i8, isize};
4 use core::{u128, u16, u32, u64, u8, usize};
5
6 /// Numbers which have upper and lower bounds
7 pub trait Bounded {
8 // FIXME (#5527): These should be associated constants
9 /// Returns the smallest finite number this type can represent
min_value() -> Self10 fn min_value() -> Self;
11 /// Returns the largest finite number this type can represent
max_value() -> Self12 fn max_value() -> Self;
13 }
14
15 /// Numbers which have lower bounds
16 pub trait LowerBounded {
17 /// Returns the smallest finite number this type can represent
min_value() -> Self18 fn min_value() -> Self;
19 }
20
21 // FIXME: With a major version bump, this should be a supertrait instead
22 impl<T: Bounded> LowerBounded for T {
min_value() -> T23 fn min_value() -> T {
24 Bounded::min_value()
25 }
26 }
27
28 /// Numbers which have upper bounds
29 pub trait UpperBounded {
30 /// Returns the largest finite number this type can represent
max_value() -> Self31 fn max_value() -> Self;
32 }
33
34 // FIXME: With a major version bump, this should be a supertrait instead
35 impl<T: Bounded> UpperBounded for T {
max_value() -> T36 fn max_value() -> T {
37 Bounded::max_value()
38 }
39 }
40
41 macro_rules! bounded_impl {
42 ($t:ty, $min:expr, $max:expr) => {
43 impl Bounded for $t {
44 #[inline]
45 fn min_value() -> $t {
46 $min
47 }
48
49 #[inline]
50 fn max_value() -> $t {
51 $max
52 }
53 }
54 };
55 }
56
57 bounded_impl!(usize, usize::MIN, usize::MAX);
58 bounded_impl!(u8, u8::MIN, u8::MAX);
59 bounded_impl!(u16, u16::MIN, u16::MAX);
60 bounded_impl!(u32, u32::MIN, u32::MAX);
61 bounded_impl!(u64, u64::MIN, u64::MAX);
62 bounded_impl!(u128, u128::MIN, u128::MAX);
63
64 bounded_impl!(isize, isize::MIN, isize::MAX);
65 bounded_impl!(i8, i8::MIN, i8::MAX);
66 bounded_impl!(i16, i16::MIN, i16::MAX);
67 bounded_impl!(i32, i32::MIN, i32::MAX);
68 bounded_impl!(i64, i64::MIN, i64::MAX);
69 bounded_impl!(i128, i128::MIN, i128::MAX);
70
71 impl<T: Bounded> Bounded for Wrapping<T> {
min_value() -> Self72 fn min_value() -> Self {
73 Wrapping(T::min_value())
74 }
max_value() -> Self75 fn max_value() -> Self {
76 Wrapping(T::max_value())
77 }
78 }
79
80 bounded_impl!(f32, f32::MIN, f32::MAX);
81
82 macro_rules! for_each_tuple_ {
83 ( $m:ident !! ) => (
84 $m! { }
85 );
86 ( $m:ident !! $h:ident, $($t:ident,)* ) => (
87 $m! { $h $($t)* }
88 for_each_tuple_! { $m !! $($t,)* }
89 );
90 }
91 macro_rules! for_each_tuple {
92 ($m:ident) => {
93 for_each_tuple_! { $m !! A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P, Q, R, S, T, }
94 };
95 }
96
97 macro_rules! bounded_tuple {
98 ( $($name:ident)* ) => (
99 impl<$($name: Bounded,)*> Bounded for ($($name,)*) {
100 #[inline]
101 fn min_value() -> Self {
102 ($($name::min_value(),)*)
103 }
104 #[inline]
105 fn max_value() -> Self {
106 ($($name::max_value(),)*)
107 }
108 }
109 );
110 }
111
112 for_each_tuple!(bounded_tuple);
113 bounded_impl!(f64, f64::MIN, f64::MAX);
114
115 #[test]
wrapping_bounded()116 fn wrapping_bounded() {
117 macro_rules! test_wrapping_bounded {
118 ($($t:ty)+) => {
119 $(
120 assert_eq!(<Wrapping<$t> as Bounded>::min_value().0, <$t>::min_value());
121 assert_eq!(<Wrapping<$t> as Bounded>::max_value().0, <$t>::max_value());
122 )+
123 };
124 }
125
126 test_wrapping_bounded!(usize u8 u16 u32 u64 isize i8 i16 i32 i64);
127 }
128
129 #[test]
wrapping_bounded_i128()130 fn wrapping_bounded_i128() {
131 macro_rules! test_wrapping_bounded {
132 ($($t:ty)+) => {
133 $(
134 assert_eq!(<Wrapping<$t> as Bounded>::min_value().0, <$t>::min_value());
135 assert_eq!(<Wrapping<$t> as Bounded>::max_value().0, <$t>::max_value());
136 )+
137 };
138 }
139
140 test_wrapping_bounded!(u128 i128);
141 }
142
143 #[test]
wrapping_is_bounded()144 fn wrapping_is_bounded() {
145 fn require_bounded<T: Bounded>(_: &T) {}
146 require_bounded(&Wrapping(42_u32));
147 require_bounded(&Wrapping(-42));
148 }
149