Struct First

pub struct First<T>(pub Option<T>);

A semigroup over Option by returning the first value available.

let five = First::from(5);
let no_value = First(None);
let ten = First::from(10);
assert_eq!(First::from(10), ten.combine(five));
assert_eq!(First::from(10), ten.combine(no_value));
assert_eq!(First(None), no_value.combine(no_value));

Tuple Fields

0: Option<T>

Trait Implementations

impl<T: Clone> Clone for First<T>

fn clone(&self) -> First<T>

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl<T: Debug> Debug for First<T>

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

Formats the value using the given formatter.

impl<T> Default for First<T>

fn default() -> Self

Returns the “default value” for a type.

impl<T> From<First<T>> for Option<T>

fn from(value: First<T>) -> Self

Converts to this type from the input type.

impl<T> From<Option<T>> for First<T>

fn from(value: Option<T>) -> Self

Converts to this type from the input type.

impl<T> From<T> for First<T>

fn from(value: T) -> Self

Converts to this type from the input type.

impl<T: Hash> Hash for First<T>

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, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl<T: Ord> Ord for First<T>

fn cmp(&self, other: &First<T>) -> Ordering

This method returns an Ordering between self and other.

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

where Self: Sized,

Compares and returns the maximum of two values.

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

where Self: Sized,

Compares and returns the minimum of two values.

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

where Self: Sized,

Restrict a value to a certain interval.

impl<T: PartialEq> PartialEq for First<T>

fn eq(&self, other: &First<T>) -> 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<T: PartialOrd> PartialOrd for First<T>

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

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

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

Tests less than (for self and other) and is used by the < operator.

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

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

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

Tests greater than (for self and other) and is used by the > operator.

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

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

impl<T> Semigroup for First<T>

fn combine(self, rhs: Self) -> Self

impl<T: Copy> Copy for First<T>

impl<T: Eq> Eq for First<T>

impl<T> StructuralPartialEq for First<T>