Trait Wrap

Source

pub trait Wrap<Bound = Self>: Sized {
    // Required methods
    fn wrapped(self, upper: Bound) -> Self;
    fn wrapped_between(self, lower: Bound, upper: Bound) -> Self;
    fn pingpong(self, upper: Bound) -> Self;

    // Provided methods
    fn wrap(val: Self, upper: Bound) -> Self { ... }
    fn wrapped_2pi(self) -> Self
       where Bound: FloatConst + Add<Output = Bound> { ... }
    fn wrap_2pi(val: Self) -> Self
       where Bound: FloatConst + Add<Output = Bound> { ... }
    fn wrap_between(val: Self, lower: Bound, upper: Bound) -> Self
       where Self: Sub<Output = Self> + Add<Output = Self> + From<Bound>,
             Bound: Copy + Sub<Output = Bound> + PartialOrd { ... }
    fn delta_angle(self, target: Self) -> Self
       where Self: From<Bound> + Sub<Output = Self> + PartialOrd,
             Bound: FloatConst + Add<Output = Bound> { ... }
    fn delta_angle_degrees(self, target: Self) -> Self
       where Self: From<Bound> + Sub<Output = Self> + PartialOrd,
             Bound: From<u16> { ... }
}

Expand description

A value that can wrap itself around given bounds.

Required Methods§

Source

fn wrapped(self, upper: Bound) -> Self

Returns this value, wrapped between zero and some upper bound (both inclusive).

The computation is self - (self/upper).floor() * upper.

This might look like the remainder (%) operator, but behaves differently with negative values.

If you’re familiar with Unity, this is the Mathf.Repeat() function.

§Panics

Panics if upper <= 0. Reasons include :

Some types may implement it as self.wrapped_between(zero, upper). A negative upper would violate the lower <= upper requirement in this case;
On unsigned integers, this just resolves to self % upper, and integer division by zero is forbidden. Testing for i==0 incurs unnecessary overhead.
Handling negative upper values would double the number of test cases and increases implementation complexity;

use vek::ops::Wrap;

assert_eq!((-5_i32).wrapped(3), 1);
assert_eq!((-4_i32).wrapped(3), 2);
assert_eq!((-3_i32).wrapped(3), 0);
assert_eq!((-2_i32).wrapped(3), 1);
assert_eq!((-1_i32).wrapped(3), 2);
assert_eq!(0_i32.wrapped(3), 0);
assert_eq!(1_i32.wrapped(3), 1);
assert_eq!(2_i32.wrapped(3), 2);
assert_eq!(3_i32.wrapped(3), 0);
assert_eq!(4_i32.wrapped(3), 1);
assert_eq!(5_i32.wrapped(3), 2);

Source

fn wrapped_between(self, lower: Bound, upper: Bound) -> Self

Returns this value, wrapped between lower (inclusive) and upper (exclusive).

§Panics

Panics if lower >= upper. Swap the values yourself if necessary.

Also panics if lower < 0 or upper <= 0. See wrapped() for a rationale. Forcing lower and upper to be positive allows implementations to be simpler and faster.

use vek::ops::Wrap;

assert_eq!((-4_i32).wrapped_between(2, 5), 2);
assert_eq!((-3_i32).wrapped_between(2, 5), 3);
assert_eq!((-2_i32).wrapped_between(2, 5), 4);
assert_eq!((-1_i32).wrapped_between(2, 5), 2);
assert_eq!(  0_i32 .wrapped_between(2, 5), 3);
assert_eq!(  1_i32 .wrapped_between(2, 5), 4);
assert_eq!(  2_i32 .wrapped_between(2, 5), 2);
assert_eq!(  3_i32 .wrapped_between(2, 5), 3);
assert_eq!(  4_i32 .wrapped_between(2, 5), 4);
assert_eq!(  5_i32 .wrapped_between(2, 5), 2);
assert_eq!(  6_i32 .wrapped_between(2, 5), 3);

Source

fn pingpong(self, upper: Bound) -> Self

Wraps a value such that it goes back and forth from zero to upper (inclusive) as it increases.

§Panics

Panics if upper <= 0. See wrapped() for a rationale.

use vek::ops::Wrap;

assert_eq!((-4_i32).pingpong(3), 2);
assert_eq!((-3_i32).pingpong(3), 3);
assert_eq!((-2_i32).pingpong(3), 2);
assert_eq!((-1_i32).pingpong(3), 1);
assert_eq!(  0_i32 .pingpong(3), 0);
assert_eq!(  1_i32 .pingpong(3), 1);
assert_eq!(  2_i32 .pingpong(3), 2);
assert_eq!(  3_i32 .pingpong(3), 3);
assert_eq!(  4_i32 .pingpong(3), 2);
assert_eq!(  5_i32 .pingpong(3), 1);
assert_eq!(  6_i32 .pingpong(3), 0);
assert_eq!(  7_i32 .pingpong(3), 1);