Struct tightness::Bounded

pub struct Bounded<T, B: Bound<Target = T>>(_, _);

A bounded type, i.e. a thin wrapper around an inner type that guarantees a specific invariant is always held. Generic over an inner type T and a Bound that targets it.

Bounded types can be constructed directly or through the bound macro:

// Defined directly
use tightness::{Bounded, Bound};

#[derive(Debug)]
pub struct LetterBound;

impl tightness::Bound for LetterBound {
    type Target = char;
    fn check(target: &char) -> bool { target.is_alphabetic() }
}

pub type Letter = tightness::Bounded<char, LetterBound>;

// Defined via macro
use tightness::{bound, Bounded};
bound!(pub Letter: char where |l| l.is_alphabetic());

Implementations

impl<T, B: Bound<Target = T>> Bounded<T, B>

pub fn new(t: T) -> Result<Self, ConstructionError<T>>

Fallible constructor. Will return an error if the argument t doesn’t fulfill the conditions of the bound.

bound!(Letter: char where |c| c.is_alphabetic());
assert!(Letter::new('a').is_ok());
assert!(matches!(Letter::new('5'), Err(ConstructionError('5'))));

pub fn mutate(&mut self, f: impl FnOnce(&mut T))

Will panic if the conditions of the bound don’t hold after mutation.

bound!(Letter: char where |c| c.is_alphabetic());
let mut letter = Letter::new('a').unwrap();
letter.mutate(|l| *l = 'b');

// Panics:
letter.mutate(|l| *l = '5');

pub fn mutate_or(
    &mut self,
    default: Self,
    f: impl FnOnce(&mut T)
) -> Result<(), MutationError<T>>

If the conditions of the bound don’t hold after mutation, will restore to a given value.

bound!(Letter: char where |c| c.is_alphabetic());
let mut letter = Letter::new('a').unwrap();
let mut fallback = Letter::new('b').unwrap();

letter.mutate_or(fallback, |l| *l = '5').unwrap_err();
assert_eq!(*letter, 'b');

pub fn into_mutated(
    self,
    f: impl FnOnce(&mut T)
) -> Result<Self, MutationError<T>>

The value is dropped if the conditions of the bound don’t hold after mutation.

bound!(Letter: char where |c| c.is_alphabetic());
let mut letter = Letter::new('a').unwrap();

let letter = letter.into_mutated(|l| *l = 'b').unwrap();
let result = letter.into_mutated(|l| *l = '5');

assert!(matches!(result, Err(MutationError(Some('5')))));

pub fn get(&self) -> &T

Access the inner value through an immutable reference.

pub fn into_inner(self) -> T

Retrieve the inner, unprotected value.

impl<T: Clone, B: Bound<Target = T>> Bounded<T, B>

pub fn try_mutate(
    &mut self,
    f: impl FnOnce(&mut T)
) -> Result<(), MutationError<T>>

Preserves invariants after mutation, erroring out if the attempt to mutate was invalid. Requires a copy to ensure the value is recoverable.

Trait Implementations

impl<T, B: Bound<Target = T>> AsRef<T> for Bounded<T, B>

fn as_ref(&self) -> &T

Performs the conversion.

impl<T, B: Bound<Target = T>> Borrow<T> for Bounded<T, B>

fn borrow(&self) -> &T

Immutably borrows from an owned value.

impl<T: Clone, B: Bound<Target = T>> Clone for Bounded<T, B>

fn clone(&self) -> Self

Returns a copy of the value.

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

Performs copy-assignment from source.

impl<T: Debug, B: Debug + Bound<Target = T>> Debug for Bounded<T, B>

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

Formats the value using the given formatter.

impl<T, B: Bound<Target = T>> Deref for Bounded<T, B>

type Target = T

The resulting type after dereferencing.

fn deref(&self) -> &Self::Target

Dereferences the value.

impl<T: Hash, B: Bound<Target = T>> Hash for Bounded<T, B>

fn hash<H: Hasher>(&self, state: &mut H)

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H) where
    H: Hasher, 

Feeds a slice of this type into the given Hasher.

impl<T: Index<U>, U, B: Bound<Target = T>> Index<U> for Bounded<T, B>

type Output = T::Output

The returned type after indexing.

fn index(&self, index: U) -> &Self::Output

Performs the indexing (container[index]) operation.

impl<T: Ord, B: Bound<Target = T>> Ord for Bounded<T, B>

fn cmp(&self, other: &Self) -> Ordering

This method returns an Ordering between self and other.

#[must_use]

fn max(self, other: Self) -> Self

Compares and returns the maximum of two values.

#[must_use]

fn min(self, other: Self) -> Self

Compares and returns the minimum of two values.

#[must_use]

fn clamp(self, min: Self, max: Self) -> Self

Restrict a value to a certain interval.

impl<T: PartialEq, B: Bound<Target = T>> PartialEq<Bounded<T, B>> for Bounded<T, B>

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

This method tests for self and other values to be equal, and is used by ==.

#[must_use]

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

This method tests for !=.

impl<T: PartialOrd, B: Bound<Target = T>> PartialOrd<Bounded<T, B>> for Bounded<T, B>

fn partial_cmp(&self, other: &Self) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

#[must_use]

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

This method tests less than (for self and other) and is used by the < operator.

#[must_use]

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

This method tests less than or equal to (for self and other) and is used by the <= operator.

#[must_use]

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

This method tests greater than (for self and other) and is used by the > operator.

#[must_use]

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

This method tests greater than or equal to (for self and other) and is used by the >= operator.

impl<T: Copy, B: Bound<Target = T>> Copy for Bounded<T, B>

impl<T: Eq, B: Bound<Target = T>> Eq for Bounded<T, B>