1 use core::ops::{Add, Mul, Sub};
2 #[cfg(has_i128)]
3 use core::{i128, u128};
4 use core::{i16, i32, i64, i8, isize};
5 use core::{u16, u32, u64, u8, usize};
6 
7 macro_rules! overflowing_impl {
8     ($trait_name:ident, $method:ident, $t:ty) => {
9         impl $trait_name for $t {
10             #[inline]
11             fn $method(&self, v: &Self) -> (Self, bool) {
12                 <$t>::$method(*self, *v)
13             }
14         }
15     };
16 }
17 
18 /// Performs addition with a flag for overflow.
19 pub trait OverflowingAdd: Sized + Add<Self, Output = Self> {
20     /// Returns a tuple of the sum along with a boolean indicating whether an arithmetic overflow would occur.
21     /// If an overflow would have occurred then the wrapped value is returned.
overflowing_add(&self, v: &Self) -> (Self, bool)22     fn overflowing_add(&self, v: &Self) -> (Self, bool);
23 }
24 
25 overflowing_impl!(OverflowingAdd, overflowing_add, u8);
26 overflowing_impl!(OverflowingAdd, overflowing_add, u16);
27 overflowing_impl!(OverflowingAdd, overflowing_add, u32);
28 overflowing_impl!(OverflowingAdd, overflowing_add, u64);
29 overflowing_impl!(OverflowingAdd, overflowing_add, usize);
30 #[cfg(has_i128)]
31 overflowing_impl!(OverflowingAdd, overflowing_add, u128);
32 
33 overflowing_impl!(OverflowingAdd, overflowing_add, i8);
34 overflowing_impl!(OverflowingAdd, overflowing_add, i16);
35 overflowing_impl!(OverflowingAdd, overflowing_add, i32);
36 overflowing_impl!(OverflowingAdd, overflowing_add, i64);
37 overflowing_impl!(OverflowingAdd, overflowing_add, isize);
38 #[cfg(has_i128)]
39 overflowing_impl!(OverflowingAdd, overflowing_add, i128);
40 
41 /// Performs substraction with a flag for overflow.
42 pub trait OverflowingSub: Sized + Sub<Self, Output = Self> {
43     /// Returns a tuple of the difference along with a boolean indicating whether an arithmetic overflow would occur.
44     /// If an overflow would have occurred then the wrapped value is returned.
overflowing_sub(&self, v: &Self) -> (Self, bool)45     fn overflowing_sub(&self, v: &Self) -> (Self, bool);
46 }
47 
48 overflowing_impl!(OverflowingSub, overflowing_sub, u8);
49 overflowing_impl!(OverflowingSub, overflowing_sub, u16);
50 overflowing_impl!(OverflowingSub, overflowing_sub, u32);
51 overflowing_impl!(OverflowingSub, overflowing_sub, u64);
52 overflowing_impl!(OverflowingSub, overflowing_sub, usize);
53 #[cfg(has_i128)]
54 overflowing_impl!(OverflowingSub, overflowing_sub, u128);
55 
56 overflowing_impl!(OverflowingSub, overflowing_sub, i8);
57 overflowing_impl!(OverflowingSub, overflowing_sub, i16);
58 overflowing_impl!(OverflowingSub, overflowing_sub, i32);
59 overflowing_impl!(OverflowingSub, overflowing_sub, i64);
60 overflowing_impl!(OverflowingSub, overflowing_sub, isize);
61 #[cfg(has_i128)]
62 overflowing_impl!(OverflowingSub, overflowing_sub, i128);
63 
64 /// Performs multiplication with a flag for overflow.
65 pub trait OverflowingMul: Sized + Mul<Self, Output = Self> {
66     /// Returns a tuple of the product along with a boolean indicating whether an arithmetic overflow would occur.
67     /// If an overflow would have occurred then the wrapped value is returned.
overflowing_mul(&self, v: &Self) -> (Self, bool)68     fn overflowing_mul(&self, v: &Self) -> (Self, bool);
69 }
70 
71 overflowing_impl!(OverflowingMul, overflowing_mul, u8);
72 overflowing_impl!(OverflowingMul, overflowing_mul, u16);
73 overflowing_impl!(OverflowingMul, overflowing_mul, u32);
74 overflowing_impl!(OverflowingMul, overflowing_mul, u64);
75 overflowing_impl!(OverflowingMul, overflowing_mul, usize);
76 #[cfg(has_i128)]
77 overflowing_impl!(OverflowingMul, overflowing_mul, u128);
78 
79 overflowing_impl!(OverflowingMul, overflowing_mul, i8);
80 overflowing_impl!(OverflowingMul, overflowing_mul, i16);
81 overflowing_impl!(OverflowingMul, overflowing_mul, i32);
82 overflowing_impl!(OverflowingMul, overflowing_mul, i64);
83 overflowing_impl!(OverflowingMul, overflowing_mul, isize);
84 #[cfg(has_i128)]
85 overflowing_impl!(OverflowingMul, overflowing_mul, i128);
86 
87 #[test]
test_overflowing_traits()88 fn test_overflowing_traits() {
89     fn overflowing_add<T: OverflowingAdd>(a: T, b: T) -> (T, bool) {
90         a.overflowing_add(&b)
91     }
92     fn overflowing_sub<T: OverflowingSub>(a: T, b: T) -> (T, bool) {
93         a.overflowing_sub(&b)
94     }
95     fn overflowing_mul<T: OverflowingMul>(a: T, b: T) -> (T, bool) {
96         a.overflowing_mul(&b)
97     }
98     assert_eq!(overflowing_add(5i16, 2), (7, false));
99     assert_eq!(overflowing_add(i16::MAX, 1), (i16::MIN, true));
100     assert_eq!(overflowing_sub(5i16, 2), (3, false));
101     assert_eq!(overflowing_sub(i16::MIN, 1), (i16::MAX, true));
102     assert_eq!(overflowing_mul(5i16, 2), (10, false));
103     assert_eq!(overflowing_mul(1_000_000_000i32, 10), (1410065408, true));
104 }
105