Struct NonPositive

pub struct NonPositive;

Marker type enforcing that a value is non-positive (zero or less).

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

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

Examples

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

// Generic constructor:
let x = Constrained::<_, NonPositive>::new(0).unwrap();
assert_eq!(x.into_inner(), 0);

// Associated constructor:
let y = NonPositive::new(-5).unwrap();
assert_eq!(y.into_inner(), -5);

// Error cases:
assert!(NonPositive::new(3).is_err());
assert!(NonPositive::new(f64::NAN).is_err());

Implementations

impl NonPositive

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

Constructs a Constrained<T, NonPositive> if the value is non-positive.

Errors

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

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

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

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

Trait Implementations

impl Clone for NonPositive

fn clone(&self) -> NonPositive

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 NonPositive

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

Checks that the given value satisfies this constraint.

impl Debug for NonPositive

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

Formats the value using the given formatter.

impl PartialEq for NonPositive

fn eq(&self, other: &NonPositive) -> 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 NonPositive

impl Eq for NonPositive

impl StructuralPartialEq for NonPositive