Struct Once 

pub struct Once<T>(/* private fields */);

A bulk that yields an element exactly once.

This struct is created by the once() function. See its documentation for more.

Trait Implementations

impl<T> Bulk for Once<T>

type MinLength = [(); 1]

type MaxLength = [(); 1]

fn len(&self) -> usize

Returns the exact length of the bulk.

fn is_empty(&self) -> bool

Returns true if the iterator is empty.

fn first(self) -> Option<Self::Item>

where Self::Item:, Self: Sized,

Returns the first value, and discards the rest of the bulk.

fn last(self) -> Option<Self::Item>

where Self::Item:, Self: Sized,

Returns the last value, and discards the rest of the bulk.

fn for_each<FF>(self, f: FF)

where Self: Sized, FF: FnMut(Self::Item),

Calls a closure on each element of a bulk.

fn try_for_each<FF, R>(self, f: FF) -> R

where Self: Sized, Self::Item:, FF: FnMut(Self::Item) -> R, R: Try<Output = (), Residual>,

A bulk method that applies a fallible function to each item in the bulk, stopping at the first error and returning that error.

type Nearest = Self::Nearest

type TryNearest = Self::TryNearest where Self::Item: Try

type Length = Self::Length

type Strategy<U, C> = Self::Strategy<U, C>

fn nth<L>(self, n: L) -> Option<Self::Item>

where Self: Sized, Self::Item:, L: LengthValue,

Returns the n-th value, and discards the rest of the bulk.

fn fold<B, F>(self, init: B, f: F) -> B

where Self: Sized, B:, F: FnMut(B, Self::Item) -> B,

Folds every element into an accumulator by applying an operation, returning the final result.

fn try_fold<B, F, R>(self, init: B, f: F) -> R

where B:, Self: Sized, Self::Item:, F: FnMut(B, Self::Item) -> R, R: Try<Output = B, Residual>,

TODO

fn reduce<F>(self, f: F) -> Option<Self::Item>

where Self: Sized, Self::Item:, F: FnMut(Self::Item, Self::Item) -> Self::Item,

TODO

fn try_reduce<F, R>( self, f: F, ) -> <R::Residual as Residual<Option<R::Output>>>::TryType

where Self: Sized, Self::Item:, F: FnMut(Self::Item, Self::Item) -> R, R: Try<Output = Self::Item, Residual: Residual<Option<Self::Item>, TryType: Try>>,

TODO

fn step_by<L>(self, step: L) -> StepBy<Self, L::Length<()>>

where Self: Sized, L: LengthValue,

Creates a bulk starting at the same point, but stepping by the given amount at each iteration.

fn chain<U>(self, other: U) -> Chain<Self, U::IntoBulk>

where Self: Sized, U: IntoBulk<Item = Self::Item>,

Takes two bulks and creates a new bulk over both in sequence.

fn zip<U>( self, other: U, ) -> Zip<Self, <<U as IntoContained>::IntoContained as IntoBulk>::IntoBulk>

where Self: Sized, U: IntoContainedBy<Self>,

‘Zips up’ two bulks or iterators into a single bulk of pairs. One of them must be a bulk.

fn intersperse(self, separator: Self::Item) -> Intersperse<Self>

where Self: Sized, Self::Item: Clone,

Creates a new bulk which places a copy of separator between adjacent items of the original bulk.

fn intersperse_with<G>(self, separator: G) -> IntersperseWith<Self, G>

where Self: Sized, G: FnMut() -> Self::Item,

Creates a new bulk which places an item generated by separator between adjacent items of the original bulk.

fn map<B, F>(self, f: F) -> Map<Self, F>

where Self: Sized, F: FnMut(Self::Item) -> B,

Takes a closure and creates a bulk which calls that closure on each element.

fn enumerate(self) -> Enumerate<Self>

where Self: Sized,

Creates a bulk which gives the current index together with its values.

fn enumerate_from<U>(self, initial_count: U) -> EnumerateFrom<Self, U>

where Self: Sized, U: Step + Copy,

Creates a bulk which gives the current index counting from a given initial index together with its values.

fn skip<L>(self, n: L) -> Skip<Self, L::Length<()>>

where Self: Sized, L: LengthValue,

Creates a bulk that skips the first n elements.

fn take<L>(self, n: L) -> Take<Self, L::Length<()>>

where Self: Sized, L: LengthValue,

Creates a bulk for the first n elements, or fewer if the underlying bulk/iterator is shorter.

fn flat_map<U, F>(self, f: F) -> FlatMap<Self, U, F>

where Self: Sized, U: IntoBulk<IntoBulk: StaticBulk>, F: FnMut(Self::Item) -> U,

Creates a bulk that works like map, but flattens nested structure.

fn flatten(self) -> Flatten<Self>

where Self: Sized, Self::Item: IntoBulk<IntoBulk: StaticBulk>,

Creates a bulk that flattens nested structure.

fn map_windows<F, R, const N: usize>(self, f: F) -> MapWindows<Self, F, N>

where Self: Sized, F: FnMut(&[Self::Item; N]) -> R,

Calls the given function f for each contiguous window of size N over self and returns a bulk of the outputs of f. The windows during mapping will overlap.

fn inspect<F>(self, f: F) -> Inspect<Self, F>

where Self: Sized, F: FnMut(&Self::Item),

Does something with each element of a bulk, passing the value on.

fn mutate<F>(self, f: F) -> Mutate<Self, F>

where Self: Sized, F: FnMut(&mut Self::Item),

Mutates with each element of a bulk, passing the value on.

fn collect<C, A>(self) -> C

where Self: Sized, C: FromBulk<A>, A: CollectionAdapter<Elem = Self::Item> + CollectionStrategy<Self, C> + ?Sized,

Transforms a bulk into a collection.

fn try_collect<C, A>( self, ) -> <<Self::Item as Try>::Residual as Residual<C>>::TryType

where Self: Sized, C: FromBulk<A>, A: CollectionAdapter<Elem = <Self::Item as Try>::Output> + TryCollectionAdapter<Self, C> + ?Sized, Self::Item: Try<Residual: Residual<C, TryType: Try>>,

Fallibly transforms a bulk into a collection, short circuiting if a failure is encountered.

fn collect_array( self, ) -> <Self as StaticBulk>::Array<<Self as IntoIterator>::Item>

where Self: StaticBulk,

Transforms a statically sized bulk into an array. The bulk must implement StaticBulk.

fn try_collect_array( self, ) -> <<Self::Item as Try>::Residual as Residual<Self::Array<<Self::Item as Try>::Output>>>::TryType

where Self: StaticBulk<Item: Try<Residual: Residual<(), TryType: Try> + Residual<Self::Array<<Self::Item as Try>::Output>, TryType: Try>, Output>> + Bulk,

Fallibly transforms a statically sized bulk into an array, short circuiting if a failure is encountered. The bulk must implement StaticBulk.

fn collect_nearest(self) -> Self::Nearest

where Self: Sized, Self::Nearest: FromBulk<Self::Strategy<Self::Item, Self::Nearest>>, Self::Strategy<Self::Item, Self::Nearest>: CollectionAdapter<Elem = Self::Item> + CollectionStrategy<Self, Self::Nearest>,

Collects into an array if possible, otherwise a vector (if feature “alloc” is enabled)

fn try_collect_nearest( self, ) -> <<Self::Item as Try>::Residual as Residual<Self::TryNearest>>::TryType

where Self: Sized, Self::TryNearest: FromBulk<Self::Strategy<<Self::Item as Try>::Output, Self::TryNearest>>, Self::Strategy<<Self::Item as Try>::Output, Self::TryNearest>: CollectionAdapter<Elem = <Self::Item as Try>::Output> + TryCollectionAdapter<Self, Self::TryNearest>, Self::Item: Try<Residual: Residual<Self::TryNearest, TryType: Try>>,

Fallibly collects into an array if possible, otherwise a vector (if feature “alloc” is enabled)

fn rev(self) -> Rev<Self>

where Self: Sized + DoubleEndedBulk,

Reverses a bulks’s direction.

fn copied<'a, T>(self) -> Copied<Self>

where T: Copy + 'a, Self: Sized + Bulk<Item = &'a T>,

Creates a bulk which copies all of its elements.

fn cloned<'a, T>(self) -> Cloned<Self>

where T: Clone + 'a, Self: Sized + Bulk<Item = &'a T>,

Creates a bulk which clones all of its elements.

fn array_chunks<const N: usize>(self) -> ArrayChunks<Self, N>

where Self: Sized,

Returns a bulk of N elements of the bulk at a time.

impl<T: Clone> Clone for Once<T>

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

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl<T: Debug> Debug for Once<T>

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

Formats the value using the given formatter.

impl<T> DoubleEndedBulk for Once<T>

fn rev_for_each<FF>(self, f: FF)

where Self: Sized, FF: FnMut(Self::Item),

Calls a closure on each element of a bulk in reverse.

fn try_rev_for_each<FF, R>(self, f: FF) -> R

where Self: Sized, Self::Item:, FF: FnMut(Self::Item) -> R, R: Try<Output = (), Residual>,

A bulk method that applies a fallible function to each item in the bulk in reverse, stopping at the first error and returning that error.

impl<A> From<Once<A>> for OnceWith<YieldOnce<A>>

fn from(value: Once<A>) -> Self

Converts to this type from the input type.

impl<A> From<Once<A>> for RepeatN<A, [(); 1]>

where A: Clone,

fn from(value: Once<A>) -> Self

Converts to this type from the input type.

impl<A> From<Once<A>> for RepeatNWith<TakeOne<YieldOnce<A>>, [(); 1]>

fn from(value: Once<A>) -> Self

Converts to this type from the input type.

impl<F, A> From<OnceWith<F>> for Once<A>

where F: FnOnce() -> A,

fn from(value: OnceWith<F>) -> Self

Converts to this type from the input type.

impl<T> IntoIterator for Once<T>

type Item = T

The type of the elements being iterated over.

type IntoIter = Once<T>

Which kind of iterator are we turning this into?

fn into_iter(self) -> Self::IntoIter

Creates an iterator from a value.

impl<A, L> SplitBulk<L> for Once<A>

where L: LengthValue, OnceWith<YieldOnce<A>>: SplitBulk<L, Item = A, Left: Bulk, Right: Bulk>,

type Left = <OnceWith<YieldOnce<A>> as SplitBulk<L>>::Left

type Right = <OnceWith<YieldOnce<A>> as SplitBulk<L>>::Right

fn split_at(self, n: L) -> (Self::Left, Self::Right)

where Self: Sized,

Splits a bulk in two at a specified index.