/rust/registry/src/index.crates.io-6f17d22bba15001f/num-traits-0.2.15/src/identities.rs

Source (jump to first uncovered line)
use core::num::Wrapping;
use core::ops::{Add, Mul};

/// Defines an additive identity element for `Self`.
///
/// # Laws
///
/// ```{.text}
/// a + 0 = a       ∀ a ∈ Self
/// 0 + a = a       ∀ a ∈ Self
/// ```
pub trait Zero: Sized + Add<Self, Output = Self> {
    /// Returns the additive identity element of `Self`, `0`.
    /// # Purity
    ///
    /// This function should return the same result at all times regardless of
    /// external mutable state, for example values stored in TLS or in
    /// `static mut`s.
    // This cannot be an associated constant, because of bignums.
    fn zero() -> Self;

    /// Sets `self` to the additive identity element of `Self`, `0`.
    fn set_zero(&mut self) {
        *self = Zero::zero();
    }

    /// Returns `true` if `self` is equal to the additive identity.
    fn is_zero(&self) -> bool;
}

macro_rules! zero_impl {
    ($t:ty, $v:expr) => {
        impl Zero for $t {
            #[inline]
            fn zero() -> $t {
                $v
            }
            #[inline]
            fn is_zero(&self) -> bool {
                *self == $v
            }
        }
    };
}

zero_impl!(usize, 0);
zero_impl!(u8, 0);
zero_impl!(u16, 0);
zero_impl!(u32, 0);
zero_impl!(u64, 0);
#[cfg(has_i128)]
zero_impl!(u128, 0);

zero_impl!(isize, 0);
zero_impl!(i8, 0);
zero_impl!(i16, 0);
zero_impl!(i32, 0);
zero_impl!(i64, 0);
#[cfg(has_i128)]
zero_impl!(i128, 0);

zero_impl!(f32, 0.0);
zero_impl!(f64, 0.0);

impl<T: Zero> Zero for Wrapping<T>
where
    Wrapping<T>: Add<Output = Wrapping<T>>,
{
    fn is_zero(&self) -> bool {
        self.0.is_zero()
    }

    fn set_zero(&mut self) {
        self.0.set_zero();
    }

    fn zero() -> Self {
        Wrapping(T::zero())
    }
}

/// Defines a multiplicative identity element for `Self`.
///
/// # Laws
///
/// ```{.text}
/// a * 1 = a       ∀ a ∈ Self
/// 1 * a = a       ∀ a ∈ Self
/// ```
pub trait One: Sized + Mul<Self, Output = Self> {
    /// Returns the multiplicative identity element of `Self`, `1`.
    ///
    /// # Purity
    ///
    /// This function should return the same result at all times regardless of
    /// external mutable state, for example values stored in TLS or in
    /// `static mut`s.
    // This cannot be an associated constant, because of bignums.
    fn one() -> Self;

    /// Sets `self` to the multiplicative identity element of `Self`, `1`.
    fn set_one(&mut self) {
        *self = One::one();
    }

    /// Returns `true` if `self` is equal to the multiplicative identity.
    ///
    /// For performance reasons, it's best to implement this manually.
    /// After a semver bump, this method will be required, and the
    /// `where Self: PartialEq` bound will be removed.
    #[inline]
    fn is_one(&self) -> bool
    where
        Self: PartialEq,
    {
        *self == Self::one()
    }
}

macro_rules! one_impl {
    ($t:ty, $v:expr) => {
        impl One for $t {
            #[inline]
            fn one() -> $t {
                $v
            }
            #[inline]
            fn is_one(&self) -> bool {
                *self == $v
            }
        }
    };
}

one_impl!(usize, 1);
one_impl!(u8, 1);
one_impl!(u16, 1);
one_impl!(u32, 1);
one_impl!(u64, 1);
#[cfg(has_i128)]
one_impl!(u128, 1);

one_impl!(isize, 1);
one_impl!(i8, 1);
one_impl!(i16, 1);
one_impl!(i32, 1);
one_impl!(i64, 1);
#[cfg(has_i128)]
one_impl!(i128, 1);

one_impl!(f32, 1.0);
one_impl!(f64, 1.0);

impl<T: One> One for Wrapping<T>
where
    Wrapping<T>: Mul<Output = Wrapping<T>>,
{
    fn set_one(&mut self) {
        self.0.set_one();
    }

    fn one() -> Self {
        Wrapping(T::one())
    }
}

// Some helper functions provided for backwards compatibility.

/// Returns the additive identity, `0`.
#[inline(always)]
pub fn zero<T: Zero>() -> T {
    Zero::zero()
}

/// Returns the multiplicative identity, `1`.
#[inline(always)]
pub fn one<T: One>() -> T {
    One::one()
}

#[test]
fn wrapping_identities() {
    macro_rules! test_wrapping_identities {
        ($($t:ty)+) => {
            $(
                assert_eq!(zero::<$t>(), zero::<Wrapping<$t>>().0);
                assert_eq!(one::<$t>(), one::<Wrapping<$t>>().0);
                assert_eq!((0 as $t).is_zero(), Wrapping(0 as $t).is_zero());
                assert_eq!((1 as $t).is_zero(), Wrapping(1 as $t).is_zero());
            )+
        };
    }

    test_wrapping_identities!(isize i8 i16 i32 i64 usize u8 u16 u32 u64);
}

#[test]
fn wrapping_is_zero() {
    fn require_zero<T: Zero>(_: &T) {}
    require_zero(&Wrapping(42));
}
#[test]
fn wrapping_is_one() {
    fn require_one<T: One>(_: &T) {}
    require_one(&Wrapping(42));
}

Coverage Report

Created: 2025-06-24 06:17

Line	Count	Source (jump to first uncovered line)
1		use core::num::Wrapping;
2		use core::ops::{Add, Mul};
3
4		/// Defines an additive identity element for `Self`.
5		///
6		/// # Laws
7		///
8		/// ```{.text}
9		/// a + 0 = a ∀ a ∈ Self
10		/// 0 + a = a ∀ a ∈ Self
11		/// ```
12		pub trait Zero: Sized + Add<Self, Output = Self> {
13		/// Returns the additive identity element of `Self`, `0`.
14		/// # Purity
15		///
16		/// This function should return the same result at all times regardless of
17		/// external mutable state, for example values stored in TLS or in
18		/// `static mut`s.
19		// This cannot be an associated constant, because of bignums.
20		fn zero() -> Self;
21
22		/// Sets `self` to the additive identity element of `Self`, `0`.
23	0	fn set_zero(&mut self) {
24	0	*self = Zero::zero();
25	0	}
26
27		/// Returns `true` if `self` is equal to the additive identity.
28		fn is_zero(&self) -> bool;
29		}
30
31		macro_rules! zero_impl {
32		($t:ty, $v:expr) => {
33		impl Zero for $t {
34		#[inline]
35	0	fn zero() -> $t {
36	0	$v
37	0	} Unexecuted instantiation: <usize as num_traits::identities::Zero>::zero Unexecuted instantiation: <u8 as num_traits::identities::Zero>::zero Unexecuted instantiation: <u16 as num_traits::identities::Zero>::zero Unexecuted instantiation: <u32 as num_traits::identities::Zero>::zero Unexecuted instantiation: <u64 as num_traits::identities::Zero>::zero Unexecuted instantiation: <u128 as num_traits::identities::Zero>::zero Unexecuted instantiation: <isize as num_traits::identities::Zero>::zero Unexecuted instantiation: <i8 as num_traits::identities::Zero>::zero Unexecuted instantiation: <i16 as num_traits::identities::Zero>::zero Unexecuted instantiation: <i32 as num_traits::identities::Zero>::zero Unexecuted instantiation: <i64 as num_traits::identities::Zero>::zero Unexecuted instantiation: <i128 as num_traits::identities::Zero>::zero Unexecuted instantiation: <f32 as num_traits::identities::Zero>::zero Unexecuted instantiation: <f64 as num_traits::identities::Zero>::zero
38		#[inline]
39	0	fn is_zero(&self) -> bool {
40	0	*self == $v
41	0	} Unexecuted instantiation: <usize as num_traits::identities::Zero>::is_zero Unexecuted instantiation: <u8 as num_traits::identities::Zero>::is_zero Unexecuted instantiation: <u16 as num_traits::identities::Zero>::is_zero Unexecuted instantiation: <u32 as num_traits::identities::Zero>::is_zero Unexecuted instantiation: <u64 as num_traits::identities::Zero>::is_zero Unexecuted instantiation: <u128 as num_traits::identities::Zero>::is_zero Unexecuted instantiation: <isize as num_traits::identities::Zero>::is_zero Unexecuted instantiation: <i8 as num_traits::identities::Zero>::is_zero Unexecuted instantiation: <i16 as num_traits::identities::Zero>::is_zero Unexecuted instantiation: <i32 as num_traits::identities::Zero>::is_zero Unexecuted instantiation: <i64 as num_traits::identities::Zero>::is_zero Unexecuted instantiation: <i128 as num_traits::identities::Zero>::is_zero Unexecuted instantiation: <f32 as num_traits::identities::Zero>::is_zero Unexecuted instantiation: <f64 as num_traits::identities::Zero>::is_zero
42		}
43		};
44		}
45
46		zero_impl!(usize, 0);
47		zero_impl!(u8, 0);
48		zero_impl!(u16, 0);
49		zero_impl!(u32, 0);
50		zero_impl!(u64, 0);
51		#[cfg(has_i128)]
52		zero_impl!(u128, 0);
53
54		zero_impl!(isize, 0);
55		zero_impl!(i8, 0);
56		zero_impl!(i16, 0);
57		zero_impl!(i32, 0);
58		zero_impl!(i64, 0);
59		#[cfg(has_i128)]
60		zero_impl!(i128, 0);
61
62		zero_impl!(f32, 0.0);
63		zero_impl!(f64, 0.0);
64
65		impl<T: Zero> Zero for Wrapping<T>
66		where
67		Wrapping<T>: Add<Output = Wrapping<T>>,
68		{
69	0	fn is_zero(&self) -> bool {
70	0	self.0.is_zero()
71	0	}
72
73	0	fn set_zero(&mut self) {
74	0	self.0.set_zero();
75	0	}
76
77	0	fn zero() -> Self {
78	0	Wrapping(T::zero())
79	0	}
80		}
81
82		/// Defines a multiplicative identity element for `Self`.
83		///
84		/// # Laws
85		///
86		/// ```{.text}
87		/// a * 1 = a ∀ a ∈ Self
88		/// 1 * a = a ∀ a ∈ Self
89		/// ```
90		pub trait One: Sized + Mul<Self, Output = Self> {
91		/// Returns the multiplicative identity element of `Self`, `1`.
92		///
93		/// # Purity
94		///
95		/// This function should return the same result at all times regardless of
96		/// external mutable state, for example values stored in TLS or in
97		/// `static mut`s.
98		// This cannot be an associated constant, because of bignums.
99		fn one() -> Self;
100
101		/// Sets `self` to the multiplicative identity element of `Self`, `1`.
102	0	fn set_one(&mut self) {
103	0	*self = One::one();
104	0	}
105
106		/// Returns `true` if `self` is equal to the multiplicative identity.
107		///
108		/// For performance reasons, it's best to implement this manually.
109		/// After a semver bump, this method will be required, and the
110		/// `where Self: PartialEq` bound will be removed.
111		#[inline]
112	0	fn is_one(&self) -> bool
113	0	where
114	0	Self: PartialEq,
115	0	{
116	0	*self == Self::one()
117	0	}
118		}
119
120		macro_rules! one_impl {
121		($t:ty, $v:expr) => {
122		impl One for $t {
123		#[inline]
124	0	fn one() -> $t {
125	0	$v
126	0	} Unexecuted instantiation: <usize as num_traits::identities::One>::one Unexecuted instantiation: <u8 as num_traits::identities::One>::one Unexecuted instantiation: <u16 as num_traits::identities::One>::one Unexecuted instantiation: <u32 as num_traits::identities::One>::one Unexecuted instantiation: <u64 as num_traits::identities::One>::one Unexecuted instantiation: <u128 as num_traits::identities::One>::one Unexecuted instantiation: <isize as num_traits::identities::One>::one Unexecuted instantiation: <i8 as num_traits::identities::One>::one Unexecuted instantiation: <i16 as num_traits::identities::One>::one Unexecuted instantiation: <i32 as num_traits::identities::One>::one Unexecuted instantiation: <i64 as num_traits::identities::One>::one Unexecuted instantiation: <i128 as num_traits::identities::One>::one Unexecuted instantiation: <f32 as num_traits::identities::One>::one Unexecuted instantiation: <f64 as num_traits::identities::One>::one
127		#[inline]
128	0	fn is_one(&self) -> bool {
129	0	*self == $v
130	0	} Unexecuted instantiation: <usize as num_traits::identities::One>::is_one Unexecuted instantiation: <u8 as num_traits::identities::One>::is_one Unexecuted instantiation: <u16 as num_traits::identities::One>::is_one Unexecuted instantiation: <u32 as num_traits::identities::One>::is_one Unexecuted instantiation: <u64 as num_traits::identities::One>::is_one Unexecuted instantiation: <u128 as num_traits::identities::One>::is_one Unexecuted instantiation: <isize as num_traits::identities::One>::is_one Unexecuted instantiation: <i8 as num_traits::identities::One>::is_one Unexecuted instantiation: <i16 as num_traits::identities::One>::is_one Unexecuted instantiation: <i32 as num_traits::identities::One>::is_one Unexecuted instantiation: <i64 as num_traits::identities::One>::is_one Unexecuted instantiation: <i128 as num_traits::identities::One>::is_one Unexecuted instantiation: <f32 as num_traits::identities::One>::is_one Unexecuted instantiation: <f64 as num_traits::identities::One>::is_one
131		}
132		};
133		}
134
135		one_impl!(usize, 1);
136		one_impl!(u8, 1);
137		one_impl!(u16, 1);
138		one_impl!(u32, 1);
139		one_impl!(u64, 1);
140		#[cfg(has_i128)]
141		one_impl!(u128, 1);
142
143		one_impl!(isize, 1);
144		one_impl!(i8, 1);
145		one_impl!(i16, 1);
146		one_impl!(i32, 1);
147		one_impl!(i64, 1);
148		#[cfg(has_i128)]
149		one_impl!(i128, 1);
150
151		one_impl!(f32, 1.0);
152		one_impl!(f64, 1.0);
153
154		impl<T: One> One for Wrapping<T>
155		where
156		Wrapping<T>: Mul<Output = Wrapping<T>>,
157		{
158	0	fn set_one(&mut self) {
159	0	self.0.set_one();
160	0	}
161
162	0	fn one() -> Self {
163	0	Wrapping(T::one())
164	0	}
165		}
166
167		// Some helper functions provided for backwards compatibility.
168
169		/// Returns the additive identity, `0`.
170		#[inline(always)]
171	0	pub fn zero<T: Zero>() -> T {
172	0	Zero::zero()
173	0	}
174
175		/// Returns the multiplicative identity, `1`.
176		#[inline(always)]
177	0	pub fn one<T: One>() -> T {
178	0	One::one()
179	0	}
180
181		#[test]
182		fn wrapping_identities() {
183		macro_rules! test_wrapping_identities {
184		($($t:ty)+) => {
185		$(
186		assert_eq!(zero::<$t>(), zero::<Wrapping<$t>>().0);
187		assert_eq!(one::<$t>(), one::<Wrapping<$t>>().0);
188		assert_eq!((0 as $t).is_zero(), Wrapping(0 as $t).is_zero());
189		assert_eq!((1 as $t).is_zero(), Wrapping(1 as $t).is_zero());
190		)+
191		};
192		}
193
194		test_wrapping_identities!(isize i8 i16 i32 i64 usize u8 u16 u32 u64);
195		}
196
197		#[test]
198		fn wrapping_is_zero() {
199		fn require_zero<T: Zero>(_: &T) {}
200		require_zero(&Wrapping(42));
201		}
202		#[test]
203		fn wrapping_is_one() {
204		fn require_one<T: One>(_: &T) {}
205		require_one(&Wrapping(42));
206		}