1 use core::ops::{Add, Mul, Sub};
2 use core::{i128, i16, i32, i64, i8, isize};
3 use core::{u128, u16, u32, u64, u8, usize};
4 
5 macro_rules! overflowing_impl {
6     ($trait_name:ident, $method:ident, $t:ty) => {
7         impl $trait_name for $t {
8             #[inline]
9             fn $method(&self, v: &Self) -> (Self, bool) {
10                 <$t>::$method(*self, *v)
11             }
12         }
13     };
14 }
15 
16 /// Performs addition with a flag for overflow.
17 pub trait OverflowingAdd: Sized + Add<Self, Output = Self> {
18     /// Returns a tuple of the sum along with a boolean indicating whether an arithmetic overflow would occur.
19     /// If an overflow would have occurred then the wrapped value is returned.
overflowing_add(&self, v: &Self) -> (Self, bool)20     fn overflowing_add(&self, v: &Self) -> (Self, bool);
21 }
22 
23 overflowing_impl!(OverflowingAdd, overflowing_add, u8);
24 overflowing_impl!(OverflowingAdd, overflowing_add, u16);
25 overflowing_impl!(OverflowingAdd, overflowing_add, u32);
26 overflowing_impl!(OverflowingAdd, overflowing_add, u64);
27 overflowing_impl!(OverflowingAdd, overflowing_add, usize);
28 overflowing_impl!(OverflowingAdd, overflowing_add, u128);
29 
30 overflowing_impl!(OverflowingAdd, overflowing_add, i8);
31 overflowing_impl!(OverflowingAdd, overflowing_add, i16);
32 overflowing_impl!(OverflowingAdd, overflowing_add, i32);
33 overflowing_impl!(OverflowingAdd, overflowing_add, i64);
34 overflowing_impl!(OverflowingAdd, overflowing_add, isize);
35 overflowing_impl!(OverflowingAdd, overflowing_add, i128);
36 
37 /// Performs substraction with a flag for overflow.
38 pub trait OverflowingSub: Sized + Sub<Self, Output = Self> {
39     /// Returns a tuple of the difference along with a boolean indicating whether an arithmetic overflow would occur.
40     /// If an overflow would have occurred then the wrapped value is returned.
overflowing_sub(&self, v: &Self) -> (Self, bool)41     fn overflowing_sub(&self, v: &Self) -> (Self, bool);
42 }
43 
44 overflowing_impl!(OverflowingSub, overflowing_sub, u8);
45 overflowing_impl!(OverflowingSub, overflowing_sub, u16);
46 overflowing_impl!(OverflowingSub, overflowing_sub, u32);
47 overflowing_impl!(OverflowingSub, overflowing_sub, u64);
48 overflowing_impl!(OverflowingSub, overflowing_sub, usize);
49 overflowing_impl!(OverflowingSub, overflowing_sub, u128);
50 
51 overflowing_impl!(OverflowingSub, overflowing_sub, i8);
52 overflowing_impl!(OverflowingSub, overflowing_sub, i16);
53 overflowing_impl!(OverflowingSub, overflowing_sub, i32);
54 overflowing_impl!(OverflowingSub, overflowing_sub, i64);
55 overflowing_impl!(OverflowingSub, overflowing_sub, isize);
56 overflowing_impl!(OverflowingSub, overflowing_sub, i128);
57 
58 /// Performs multiplication with a flag for overflow.
59 pub trait OverflowingMul: Sized + Mul<Self, Output = Self> {
60     /// Returns a tuple of the product along with a boolean indicating whether an arithmetic overflow would occur.
61     /// If an overflow would have occurred then the wrapped value is returned.
overflowing_mul(&self, v: &Self) -> (Self, bool)62     fn overflowing_mul(&self, v: &Self) -> (Self, bool);
63 }
64 
65 overflowing_impl!(OverflowingMul, overflowing_mul, u8);
66 overflowing_impl!(OverflowingMul, overflowing_mul, u16);
67 overflowing_impl!(OverflowingMul, overflowing_mul, u32);
68 overflowing_impl!(OverflowingMul, overflowing_mul, u64);
69 overflowing_impl!(OverflowingMul, overflowing_mul, usize);
70 overflowing_impl!(OverflowingMul, overflowing_mul, u128);
71 
72 overflowing_impl!(OverflowingMul, overflowing_mul, i8);
73 overflowing_impl!(OverflowingMul, overflowing_mul, i16);
74 overflowing_impl!(OverflowingMul, overflowing_mul, i32);
75 overflowing_impl!(OverflowingMul, overflowing_mul, i64);
76 overflowing_impl!(OverflowingMul, overflowing_mul, isize);
77 overflowing_impl!(OverflowingMul, overflowing_mul, i128);
78 
79 #[test]
test_overflowing_traits()80 fn test_overflowing_traits() {
81     fn overflowing_add<T: OverflowingAdd>(a: T, b: T) -> (T, bool) {
82         a.overflowing_add(&b)
83     }
84     fn overflowing_sub<T: OverflowingSub>(a: T, b: T) -> (T, bool) {
85         a.overflowing_sub(&b)
86     }
87     fn overflowing_mul<T: OverflowingMul>(a: T, b: T) -> (T, bool) {
88         a.overflowing_mul(&b)
89     }
90     assert_eq!(overflowing_add(5i16, 2), (7, false));
91     assert_eq!(overflowing_add(i16::MAX, 1), (i16::MIN, true));
92     assert_eq!(overflowing_sub(5i16, 2), (3, false));
93     assert_eq!(overflowing_sub(i16::MIN, 1), (i16::MAX, true));
94     assert_eq!(overflowing_mul(5i16, 2), (10, false));
95     assert_eq!(overflowing_mul(1_000_000_000i32, 10), (1410065408, true));
96 }
97