Struct NonNegative

pub struct NonNegative;

Marker type enforcing that a value is non-negative (zero or greater).

Use this type with Constrained<T, NonNegative> to encode non-negativity at the type level.

You can construct a value constrained to be non-negative using either the generic Constrained::new method or the convenient NonNegative::new associated function.

Examples

use twine_core::constraint::{Constrained, NonNegative};

// Generic constructor:
let x = Constrained::<_, NonNegative>::new(5).unwrap();
assert_eq!(x.into_inner(), 5);

// Associated constructor:
let y = NonNegative::new(0.0).unwrap();
assert_eq!(y.into_inner(), 0.0);

// Error cases:
assert!(NonNegative::new(-7).is_err());
assert!(NonNegative::new(f64::NAN).is_err());

Implementations

impl NonNegative

pub fn new<T: PartialOrd + Zero>( value: T, ) -> Result<Constrained<T, NonNegative>, ConstraintError>

Constructs a Constrained<T, NonNegative> if the value is non-negative.

Errors

Returns an error if the value is negative or not a number (NaN).

pub fn zero<T: PartialOrd + Zero>() -> Constrained<T, NonNegative>

Returns the additive identity (zero) as a non-negative constrained value.

This method is equivalent to Constrained::<T, NonNegative>::zero().

Trait Implementations

impl Clone for NonNegative

fn clone(&self) -> NonNegative

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl<T: PartialOrd + Zero> Constraint<T> for NonNegative

fn check(value: &T) -> Result<(), ConstraintError>

Checks that the given value satisfies this constraint.

impl Debug for NonNegative

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl PartialEq for NonNegative

fn eq(&self, other: &NonNegative) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl Copy for NonNegative

impl Eq for NonNegative

impl StructuralPartialEq for NonNegative