Struct dialectic::backend::Choice

#[repr(transparent)]pub struct Choice<const N: usize> { /* fields omitted */ }

A Choice represents a selection between several protocols offered by offer!.

It wraps an ordinary non-negative number, with the guarantee that it is strictly less than the type level number N.

Unless you are implementing a backend, you do not need to interact with Choices directly. However, all backends must implement Transmit<Choice<N>, Val> and Receive<Choice<N>> for all N in order to support the Choose and Offer constructs.

Examples

It’s possible to construct a Choice from all u8 strictly less than its type parameter N:

use std::convert::TryInto;
use dialectic::backend::Choice;

let zero: Choice<3> = 0_u8.try_into()?;
let one: Choice<3> = 1_u8.try_into()?;
let two: Choice<3> = 2_u8.try_into()?;

assert_eq!(zero, 0_u8);
assert_eq!(one, 1_u8);
assert_eq!(two, 2_u8);

But we cannot construct a Choice from a u8 equal to or greater than its type parameter N:

let attempted_three: Result<Choice<3>, _> = 3_u8.try_into();
let attempted_four: Result<Choice<3>, _> = 4_u8.try_into();

assert!(attempted_three.is_err());
assert!(attempted_four.is_err());

Note that this means Choice<0> is unrepresentable, because you cannot choose something from a set of zero things:

for i in 0 ..= u8::MAX {
   let attempt: Result<Choice<0>, _> = i.try_into();
   assert!(attempt.is_err());
}

Trait Implementations

impl<const N: usize> Clone for Choice<N>

fn clone(&self) -> Choice<N>

Returns a copy of the value.

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

Performs copy-assignment from source.

impl<const N: usize> Copy for Choice<N>

impl<const N: usize> Debug for Choice<N>

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

Formats the value using the given formatter.

impl<M: Unary, const N: usize> Default for Choice<N> where
    Number<N>: ToUnary<AsUnary = S<M>>, 

fn default() -> Self

Returns the “default value” for a type.

impl<'de, const N: usize> Deserialize<'de> for Choice<N>

fn deserialize<D>(deserializer: D) -> Result<Choice<N>, D::Error> where
    D: Deserializer<'de>, 

Deserialize this value from the given Serde deserializer.

impl<const N: usize> Eq for Choice<N>

impl<const N: usize> Hash for Choice<N>

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

Feeds this value into the given Hasher.

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

Feeds a slice of this type into the given Hasher.

impl<const N: usize> Ord for Choice<N>

fn cmp(&self, other: &Choice<N>) -> Ordering

This method returns an Ordering between self and other.

#[must_use]pub fn max(self, other: Self) -> Self

Compares and returns the maximum of two values.

#[must_use]pub fn min(self, other: Self) -> Self

Compares and returns the minimum of two values.

#[must_use]pub fn clamp(self, min: Self, max: Self) -> Self

Restrict a value to a certain interval.

impl<const N: usize> PartialEq<Choice<N>> for Choice<N>

fn eq(&self, other: &Choice<N>) -> bool

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

fn ne(&self, other: &Choice<N>) -> bool

This method tests for !=.

impl<const N: usize> PartialEq<u8> for Choice<N>

fn eq(&self, other: &u8) -> bool

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

#[must_use]pub fn ne(&self, other: &Rhs) -> bool

This method tests for !=.

impl<const N: usize> PartialOrd<Choice<N>> for Choice<N>

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

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

#[must_use]pub fn lt(&self, other: &Rhs) -> bool

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

#[must_use]pub 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]pub fn gt(&self, other: &Rhs) -> bool

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

#[must_use]pub 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<const N: usize> Serialize for Choice<N>

fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error> where
    S: Serializer, 

Serialize this value into the given Serde serializer.

impl<const N: usize> StructuralEq for Choice<N>

impl<const N: usize> StructuralPartialEq for Choice<N>

impl<const N: usize> TryFrom<u8> for Choice<N>

type Error = OutOfBoundsChoiceError

The type returned in the event of a conversion error.

fn try_from(choice: u8) -> Result<Self, Self::Error>

Performs the conversion.