Enum either::Either

pub enum Either<L, R> {
    Left(L),
    Right(R),
}

The enum Either with variants Left and Right is a general purpose sum type with two cases.

The Either type is symmetric and treats its variants the same way, without preference. (For representing success or error, use the regular Result enum instead.)

Variants

Left(L)

A value of type L.

Right(R)

A value of type R.

Methods

impl<L, R> Either<L, R>

pub fn is_left(&self) -> bool

Return true if the value is the Left variant.

use either::*;

let values = [Left(1), Right("the right value")];
assert_eq!(values[0].is_left(), true);
assert_eq!(values[1].is_left(), false);

pub fn is_right(&self) -> bool

Return true if the value is the Right variant.

use either::*;

let values = [Left(1), Right("the right value")];
assert_eq!(values[0].is_right(), false);
assert_eq!(values[1].is_right(), true);

pub fn left(self) -> Option<L>

Convert the left side of Either<L, R> to an Option<L>.

use either::*;

let left: Either<_, ()> = Left("some value");
assert_eq!(left.left(),  Some("some value"));

let right: Either<(), _> = Right(321);
assert_eq!(right.left(), None);

pub fn right(self) -> Option<R>

Convert the right side of Either<L, R> to an Option<R>.

use either::*;

let left: Either<_, ()> = Left("some value");
assert_eq!(left.right(),  None);

let right: Either<(), _> = Right(321);
assert_eq!(right.right(), Some(321));

Important traits for Either<L, R>

impl<L, R> Iterator for Either<L, R> where
    L: Iterator,
    R: Iterator<Item = L::Item>,  type Item = L::Item;impl<L, R> Read for Either<L, R> where
    L: Read,
    R: Read, impl<L, R> Write for Either<L, R> where
    L: Write,
    R: Write, 

pub fn as_ref(&self) -> Either<&L, &R>

Convert &Either<L, R> to Either<&L, &R>.

use either::*;

let left: Either<_, ()> = Left("some value");
assert_eq!(left.as_ref(), Left(&"some value"));

let right: Either<(), _> = Right("some value");
assert_eq!(right.as_ref(), Right(&"some value"));

Important traits for Either<L, R>

impl<L, R> Iterator for Either<L, R> where
    L: Iterator,
    R: Iterator<Item = L::Item>,  type Item = L::Item;impl<L, R> Read for Either<L, R> where
    L: Read,
    R: Read, impl<L, R> Write for Either<L, R> where
    L: Write,
    R: Write, 

pub fn as_mut(&mut self) -> Either<&mut L, &mut R>

Convert &mut Either<L, R> to Either<&mut L, &mut R>.

use either::*;

fn mutate_left(value: &mut Either<u32, u32>) {
    if let Some(l) = value.as_mut().left() {
        *l = 999;
    }
}

let mut left = Left(123);
let mut right = Right(123);
mutate_left(&mut left);
mutate_left(&mut right);
assert_eq!(left, Left(999));
assert_eq!(right, Right(123));

Important traits for Either<L, R>

impl<L, R> Iterator for Either<L, R> where
    L: Iterator,
    R: Iterator<Item = L::Item>,  type Item = L::Item;impl<L, R> Read for Either<L, R> where
    L: Read,
    R: Read, impl<L, R> Write for Either<L, R> where
    L: Write,
    R: Write, 

pub fn flip(self) -> Either<R, L>

Convert Either<L, R> to Either<R, L>.

use either::*;

let left: Either<_, ()> = Left(123);
assert_eq!(left.flip(), Right(123));

let right: Either<(), _> = Right("some value");
assert_eq!(right.flip(), Left("some value"));

Important traits for Either<L, R>

impl<L, R> Iterator for Either<L, R> where
    L: Iterator,
    R: Iterator<Item = L::Item>,  type Item = L::Item;impl<L, R> Read for Either<L, R> where
    L: Read,
    R: Read, impl<L, R> Write for Either<L, R> where
    L: Write,
    R: Write, 

pub fn map_left<F, M>(self, f: F) -> Either<M, R> where
    F: FnOnce(L) -> M, 

Apply the function f on the value in the Left variant if it is present rewrapping the result in Left.

use either::*;

let left: Either<_, u32> = Left(123);
assert_eq!(left.map_left(|x| x * 2), Left(246));

let right: Either<u32, _> = Right(123);
assert_eq!(right.map_left(|x| x * 2), Right(123));

Important traits for Either<L, R>

impl<L, R> Iterator for Either<L, R> where
    L: Iterator,
    R: Iterator<Item = L::Item>,  type Item = L::Item;impl<L, R> Read for Either<L, R> where
    L: Read,
    R: Read, impl<L, R> Write for Either<L, R> where
    L: Write,
    R: Write, 

pub fn map_right<F, S>(self, f: F) -> Either<L, S> where
    F: FnOnce(R) -> S, 

Apply the function f on the value in the Right variant if it is present rewrapping the result in Right.

use either::*;

let left: Either<_, u32> = Left(123);
assert_eq!(left.map_right(|x| x * 2), Left(123));

let right: Either<u32, _> = Right(123);
assert_eq!(right.map_right(|x| x * 2), Right(246));

pub fn either<F, G, T>(self, f: F, g: G) -> T where
    F: FnOnce(L) -> T,
    G: FnOnce(R) -> T, 

Apply one of two functions depending on contents, unifying their result. If the value is Left(L) then the first function f is applied; if it is Right(R) then the second function g is applied.

use either::*;

fn square(n: u32) -> i32 { (n * n) as i32 }
fn negate(n: i32) -> i32 { -n }

let left: Either<u32, i32> = Left(4);
assert_eq!(left.either(square, negate), 16);

let right: Either<u32, i32> = Right(-4);
assert_eq!(right.either(square, negate), 4);

pub fn either_with<Ctx, F, G, T>(self, ctx: Ctx, f: F, g: G) -> T where
    F: FnOnce(Ctx, L) -> T,
    G: FnOnce(Ctx, R) -> T, 

Like either, but provide some context to whichever of the functions ends up being called.

// In this example, the context is a mutable reference
use either::*;

let mut result = Vec::new();

let values = vec![Left(2), Right(2.7)];

for value in values {
    value.either_with(&mut result,
                      |ctx, integer| ctx.push(integer),
                      |ctx, real| ctx.push(f64::round(real) as i32));
}

assert_eq!(result, vec![2, 3]);

Important traits for Either<L, R>

impl<L, R> Iterator for Either<L, R> where
    L: Iterator,
    R: Iterator<Item = L::Item>,  type Item = L::Item;impl<L, R> Read for Either<L, R> where
    L: Read,
    R: Read, impl<L, R> Write for Either<L, R> where
    L: Write,
    R: Write, 

pub fn left_and_then<F, S>(self, f: F) -> Either<S, R> where
    F: FnOnce(L) -> Either<S, R>, 

Apply the function f on the value in the Left variant if it is present.

use either::*;

let left: Either<_, u32> = Left(123);
assert_eq!(left.left_and_then::<_,()>(|x| Right(x * 2)), Right(246));

let right: Either<u32, _> = Right(123);
assert_eq!(right.left_and_then(|x| Right::<(), _>(x * 2)), Right(123));

Important traits for Either<L, R>

impl<L, R> Iterator for Either<L, R> where
    L: Iterator,
    R: Iterator<Item = L::Item>,  type Item = L::Item;impl<L, R> Read for Either<L, R> where
    L: Read,
    R: Read, impl<L, R> Write for Either<L, R> where
    L: Write,
    R: Write, 

pub fn right_and_then<F, S>(self, f: F) -> Either<L, S> where
    F: FnOnce(R) -> Either<L, S>, 

Apply the function f on the value in the Right variant if it is present.

use either::*;

let left: Either<_, u32> = Left(123);
assert_eq!(left.right_and_then(|x| Right(x * 2)), Left(123));

let right: Either<u32, _> = Right(123);
assert_eq!(right.right_and_then(|x| Right(x * 2)), Right(246));

Important traits for Either<L, R>

impl<L, R> Iterator for Either<L, R> where
    L: Iterator,
    R: Iterator<Item = L::Item>,  type Item = L::Item;impl<L, R> Read for Either<L, R> where
    L: Read,
    R: Read, impl<L, R> Write for Either<L, R> where
    L: Write,
    R: Write, 

pub fn into_iter(self) -> Either<L::IntoIter, R::IntoIter> where
    L: IntoIterator,
    R: IntoIterator<Item = L::Item>, 

Convert the inner value to an iterator.

use either::*;

let left: Either<_, Vec<u32>> = Left(vec![1, 2, 3, 4, 5]);
let mut right: Either<Vec<u32>, _> = Right(vec![]);
right.extend(left.into_iter());
assert_eq!(right, Right(vec![1, 2, 3, 4, 5]));

impl<T, L, R> Either<(T, L), (T, R)>

pub fn factor_first(self) -> (T, Either<L, R>)

Factor out a homogeneous type from an either of pairs.

Here, the homogeneous type is the first element of the pairs.

use either::*;
let left: Either<_, (u32, String)> = Left((123, vec![0]));
assert_eq!(left.factor_first().0, 123);

let right: Either<(u32, Vec<u8>), _> = Right((123, String::new()));
assert_eq!(right.factor_first().0, 123);

impl<T, L, R> Either<(L, T), (R, T)>

pub fn factor_second(self) -> (Either<L, R>, T)

Factor out a homogeneous type from an either of pairs.

Here, the homogeneous type is the second element of the pairs.

use either::*;
let left: Either<_, (String, u32)> = Left((vec![0], 123));
assert_eq!(left.factor_second().1, 123);

let right: Either<(Vec<u8>, u32), _> = Right((String::new(), 123));
assert_eq!(right.factor_second().1, 123);

impl<T> Either<T, T>

pub fn into_inner(self) -> T

Extract the value of an either over two equivalent types.

use either::*;

let left: Either<_, u32> = Left(123);
assert_eq!(left.into_inner(), 123);

let right: Either<u32, _> = Right(123);
assert_eq!(right.into_inner(), 123);

Trait Implementations

impl<L: Eq, R: Eq> Eq for Either<L, R>

impl<L: Copy, R: Copy> Copy for Either<L, R>

impl<L: PartialOrd, R: PartialOrd> PartialOrd<Either<L, R>> for Either<L, R>

fn partial_cmp(&self, other: &Either<L, R>) -> Option<Ordering>

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

fn lt(&self, other: &Either<L, R>) -> bool

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

fn le(&self, other: &Either<L, R>) -> bool

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

fn gt(&self, other: &Either<L, R>) -> bool

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

fn ge(&self, other: &Either<L, R>) -> bool

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

impl<L, R> AsMut<str> for Either<L, R> where
    L: AsMut<str>,
    R: AsMut<str>, 

fn as_mut(&mut self) -> &mut str

Performs the conversion.

impl<L, R> AsMut<Path> for Either<L, R> where
    L: AsMut<Path>,
    R: AsMut<Path>, 

Requires crate feature use_std.

fn as_mut(&mut self) -> &mut Path

Performs the conversion.

impl<L, R> AsMut<OsStr> for Either<L, R> where
    L: AsMut<OsStr>,
    R: AsMut<OsStr>, 

Requires crate feature use_std.

fn as_mut(&mut self) -> &mut OsStr

Performs the conversion.

impl<L, R> AsMut<CStr> for Either<L, R> where
    L: AsMut<CStr>,
    R: AsMut<CStr>, 

Requires crate feature use_std.

fn as_mut(&mut self) -> &mut CStr

Performs the conversion.

impl<L, R, Target> AsMut<Target> for Either<L, R> where
    L: AsMut<Target>,
    R: AsMut<Target>, 

fn as_mut(&mut self) -> &mut Target

Performs the conversion.

impl<L, R, Target> AsMut<[Target]> for Either<L, R> where
    L: AsMut<[Target]>,
    R: AsMut<[Target]>, 

fn as_mut(&mut self) -> &mut [Target]

Performs the conversion.

impl<L, R> Iterator for Either<L, R> where
    L: Iterator,
    R: Iterator<Item = L::Item>, 

Either<L, R> is an iterator if both L and R are iterators.

type Item = L::Item

The type of the elements being iterated over.

fn next(&mut self) -> Option<Self::Item>

Advances the iterator and returns the next value.

fn size_hint(&self) -> (usize, Option<usize>)

Returns the bounds on the remaining length of the iterator.

fn fold<Acc, G>(self, init: Acc, f: G) -> Acc where
    G: FnMut(Acc, Self::Item) -> Acc, 

An iterator method that applies a function, producing a single, final value.

fn count(self) -> usize

Consumes the iterator, counting the number of iterations and returning it.

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

Consumes the iterator, returning the last element.

fn nth(&mut self, n: usize) -> Option<Self::Item>

Returns the nth element of the iterator.

fn collect<B>(self) -> B where
    B: FromIterator<Self::Item>, 

Transforms an iterator into a collection.

fn all<F>(&mut self, f: F) -> bool where
    F: FnMut(Self::Item) -> bool, 

Tests if every element of the iterator matches a predicate.

default fn step_by(self, step: usize) -> StepBy<Self>

Creates an iterator starting at the same point, but stepping by the given amount at each iteration.

default fn chain<U>(
    self,
    other: U
) -> Chain<Self, <U as IntoIterator>::IntoIter> where
    U: IntoIterator<Item = Self::Item>, 

Takes two iterators and creates a new iterator over both in sequence.

default fn zip<U>(self, other: U) -> Zip<Self, <U as IntoIterator>::IntoIter> where
    U: IntoIterator, 

'Zips up' two iterators into a single iterator of pairs.

default fn map<B, F>(self, f: F) -> Map<Self, F> where
    F: FnMut(Self::Item) -> B, 

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

default fn for_each<F>(self, f: F) where
    F: FnMut(Self::Item), 

Calls a closure on each element of an iterator.

default fn filter<P>(self, predicate: P) -> Filter<Self, P> where
    P: FnMut(&Self::Item) -> bool, 

Creates an iterator which uses a closure to determine if an element should be yielded.

default fn filter_map<B, F>(self, f: F) -> FilterMap<Self, F> where
    F: FnMut(Self::Item) -> Option<B>, 

Creates an iterator that both filters and maps.

default fn enumerate(self) -> Enumerate<Self>

Creates an iterator which gives the current iteration count as well as the next value.

default fn peekable(self) -> Peekable<Self>

Creates an iterator which can use peek to look at the next element of the iterator without consuming it.

default fn skip_while<P>(self, predicate: P) -> SkipWhile<Self, P> where
    P: FnMut(&Self::Item) -> bool, 

Creates an iterator that [skip]s elements based on a predicate.

default fn take_while<P>(self, predicate: P) -> TakeWhile<Self, P> where
    P: FnMut(&Self::Item) -> bool, 

Creates an iterator that yields elements based on a predicate.

default fn skip(self, n: usize) -> Skip<Self>

Creates an iterator that skips the first n elements.

default fn take(self, n: usize) -> Take<Self>

Creates an iterator that yields its first n elements.

default fn scan<St, B, F>(self, initial_state: St, f: F) -> Scan<Self, St, F> where
    F: FnMut(&mut St, Self::Item) -> Option<B>, 

An iterator adaptor similar to [fold] that holds internal state and produces a new iterator.

default fn flat_map<U, F>(self, f: F) -> FlatMap<Self, U, F> where
    F: FnMut(Self::Item) -> U,
    U: IntoIterator, 

Creates an iterator that works like map, but flattens nested structure.

default fn flatten(self) -> Flatten<Self> where
    Self::Item: IntoIterator, 

Creates an iterator that flattens nested structure.

default fn fuse(self) -> Fuse<Self>

Creates an iterator which ends after the first [None].

default fn inspect<F>(self, f: F) -> Inspect<Self, F> where
    F: FnMut(&Self::Item), 

Do something with each element of an iterator, passing the value on.

default fn by_ref(&mut self) -> &mut Self

Borrows an iterator, rather than consuming it.

default fn partition<B, F>(self, f: F) -> (B, B) where
    B: Default + Extend<Self::Item>,
    F: FnMut(&Self::Item) -> bool, 

Consumes an iterator, creating two collections from it.

default fn try_fold<B, F, R>(&mut self, init: B, f: F) -> R where
    F: FnMut(B, Self::Item) -> R,
    R: Try<Ok = B>, 

An iterator method that applies a function as long as it returns successfully, producing a single, final value.

default fn try_for_each<F, R>(&mut self, f: F) -> R where
    F: FnMut(Self::Item) -> R,
    R: Try<Ok = ()>, 

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

default fn any<F>(&mut self, f: F) -> bool where
    F: FnMut(Self::Item) -> bool, 

Tests if any element of the iterator matches a predicate.

default fn find<P>(&mut self, predicate: P) -> Option<Self::Item> where
    P: FnMut(&Self::Item) -> bool, 

Searches for an element of an iterator that satisfies a predicate.

default fn find_map<B, F>(&mut self, f: F) -> Option<B> where
    F: FnMut(Self::Item) -> Option<B>, 

Applies function to the elements of iterator and returns the first non-none result.

default fn position<P>(&mut self, predicate: P) -> Option<usize> where
    P: FnMut(Self::Item) -> bool, 

Searches for an element in an iterator, returning its index.

default fn rposition<P>(&mut self, predicate: P) -> Option<usize> where
    P: FnMut(Self::Item) -> bool,
    Self: ExactSizeIterator + DoubleEndedIterator, 

Searches for an element in an iterator from the right, returning its index.

default fn max(self) -> Option<Self::Item> where
    Self::Item: Ord, 

Returns the maximum element of an iterator.

default fn min(self) -> Option<Self::Item> where
    Self::Item: Ord, 

Returns the minimum element of an iterator.

default fn max_by_key<B, F>(self, f: F) -> Option<Self::Item> where
    B: Ord,
    F: FnMut(&Self::Item) -> B, 

Returns the element that gives the maximum value from the specified function.

default fn max_by<F>(self, compare: F) -> Option<Self::Item> where
    F: FnMut(&Self::Item, &Self::Item) -> Ordering, 

Returns the element that gives the maximum value with respect to the specified comparison function.

default fn min_by_key<B, F>(self, f: F) -> Option<Self::Item> where
    B: Ord,
    F: FnMut(&Self::Item) -> B, 

Returns the element that gives the minimum value from the specified function.

default fn min_by<F>(self, compare: F) -> Option<Self::Item> where
    F: FnMut(&Self::Item, &Self::Item) -> Ordering, 

Returns the element that gives the minimum value with respect to the specified comparison function.

default fn rev(self) -> Rev<Self> where
    Self: DoubleEndedIterator, 

Reverses an iterator's direction.

default fn unzip<A, B, FromA, FromB>(self) -> (FromA, FromB) where
    FromA: Default + Extend<A>,
    FromB: Default + Extend<B>,
    Self: Iterator<Item = (A, B)>, 

Converts an iterator of pairs into a pair of containers.

default fn copied<'a, T>(self) -> Copied<Self> where
    Self: Iterator<Item = &'a T>,
    T: 'a + Copy, 

🔬 This is a nightly-only experimental API. (iter_copied)

Creates an iterator which copies all of its elements.

default fn cloned<'a, T>(self) -> Cloned<Self> where
    Self: Iterator<Item = &'a T>,
    T: 'a + Clone, 

Creates an iterator which [clone]s all of its elements.

default fn cycle(self) -> Cycle<Self> where
    Self: Clone, 

Repeats an iterator endlessly.

default fn sum<S>(self) -> S where
    S: Sum<Self::Item>, 

Sums the elements of an iterator.

default fn product<P>(self) -> P where
    P: Product<Self::Item>, 

Iterates over the entire iterator, multiplying all the elements

default fn cmp<I>(self, other: I) -> Ordering where
    I: IntoIterator<Item = Self::Item>,
    Self::Item: Ord, 

Lexicographically compares the elements of this Iterator with those of another.

default fn partial_cmp<I>(self, other: I) -> Option<Ordering> where
    I: IntoIterator,
    Self::Item: PartialOrd<<I as IntoIterator>::Item>, 

Lexicographically compares the elements of this Iterator with those of another.

default fn eq<I>(self, other: I) -> bool where
    I: IntoIterator,
    Self::Item: PartialEq<<I as IntoIterator>::Item>, 

Determines if the elements of this Iterator are equal to those of another.

default fn ne<I>(self, other: I) -> bool where
    I: IntoIterator,
    Self::Item: PartialEq<<I as IntoIterator>::Item>, 

Determines if the elements of this Iterator are unequal to those of another.

default fn lt<I>(self, other: I) -> bool where
    I: IntoIterator,
    Self::Item: PartialOrd<<I as IntoIterator>::Item>, 

Determines if the elements of this Iterator are lexicographically less than those of another.

default fn le<I>(self, other: I) -> bool where
    I: IntoIterator,
    Self::Item: PartialOrd<<I as IntoIterator>::Item>, 

Determines if the elements of this Iterator are lexicographically less or equal to those of another.

default fn gt<I>(self, other: I) -> bool where
    I: IntoIterator,
    Self::Item: PartialOrd<<I as IntoIterator>::Item>, 

Determines if the elements of this Iterator are lexicographically greater than those of another.

default fn ge<I>(self, other: I) -> bool where
    I: IntoIterator,
    Self::Item: PartialOrd<<I as IntoIterator>::Item>, 

Determines if the elements of this Iterator are lexicographically greater than or equal to those of another.

default fn is_sorted(self) -> bool where
    Self::Item: PartialOrd<Self::Item>, 

🔬 This is a nightly-only experimental API. (is_sorted)

new API

Checks if the elements of this iterator are sorted.

default fn is_sorted_by<F>(self, compare: F) -> bool where
    F: FnMut(&Self::Item, &Self::Item) -> Option<Ordering>, 

🔬 This is a nightly-only experimental API. (is_sorted)

new API

Checks if the elements of this iterator are sorted using the given comparator function.

default fn is_sorted_by_key<F, K>(self, f: F) -> bool where
    F: FnMut(&Self::Item) -> K,
    K: PartialOrd<K>, 

🔬 This is a nightly-only experimental API. (is_sorted)

new API

Checks if the elements of this iterator are sorted using the given key extraction function.

impl<L, R> ExactSizeIterator for Either<L, R> where
    L: ExactSizeIterator,
    R: ExactSizeIterator<Item = L::Item>, 

default fn len(&self) -> usize

Returns the exact number of times the iterator will iterate.

default fn is_empty(&self) -> bool

🔬 This is a nightly-only experimental API. (exact_size_is_empty)

Returns true if the iterator is empty.

impl<L: PartialEq, R: PartialEq> PartialEq<Either<L, R>> for Either<L, R>

fn eq(&self, other: &Either<L, R>) -> bool

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

fn ne(&self, other: &Either<L, R>) -> bool

This method tests for !=.

impl<L, R, Target> AsRef<Target> for Either<L, R> where
    L: AsRef<Target>,
    R: AsRef<Target>, 

fn as_ref(&self) -> &Target

Performs the conversion.

impl<L, R> AsRef<str> for Either<L, R> where
    L: AsRef<str>,
    R: AsRef<str>, 

fn as_ref(&self) -> &str

Performs the conversion.

impl<L, R> AsRef<Path> for Either<L, R> where
    L: AsRef<Path>,
    R: AsRef<Path>, 

Requires crate feature use_std.

fn as_ref(&self) -> &Path

Performs the conversion.

impl<L, R> AsRef<OsStr> for Either<L, R> where
    L: AsRef<OsStr>,
    R: AsRef<OsStr>, 

Requires crate feature use_std.

fn as_ref(&self) -> &OsStr

Performs the conversion.

impl<L, R> AsRef<CStr> for Either<L, R> where
    L: AsRef<CStr>,
    R: AsRef<CStr>, 

Requires crate feature use_std.

fn as_ref(&self) -> &CStr

Performs the conversion.

impl<L, R, Target> AsRef<[Target]> for Either<L, R> where
    L: AsRef<[Target]>,
    R: AsRef<[Target]>, 

fn as_ref(&self) -> &[Target]

Performs the conversion.

impl<L, R> DoubleEndedIterator for Either<L, R> where
    L: DoubleEndedIterator,
    R: DoubleEndedIterator<Item = L::Item>, 

fn next_back(&mut self) -> Option<Self::Item>

Removes and returns an element from the end of the iterator.

default fn nth_back(&mut self, n: usize) -> Option<Self::Item>

🔬 This is a nightly-only experimental API. (iter_nth_back)

Returns the nth element from the end of the iterator.

default fn try_rfold<B, F, R>(&mut self, init: B, f: F) -> R where
    F: FnMut(B, Self::Item) -> R,
    R: Try<Ok = B>, 

This is the reverse version of [try_fold()]: it takes elements starting from the back of the iterator.

default fn rfold<B, F>(self, accum: B, f: F) -> B where
    F: FnMut(B, Self::Item) -> B, 

An iterator method that reduces the iterator's elements to a single, final value, starting from the back.

default fn rfind<P>(&mut self, predicate: P) -> Option<Self::Item> where
    P: FnMut(&Self::Item) -> bool, 

Searches for an element of an iterator from the back that satisfies a predicate.

impl<L: Clone, R: Clone> Clone for Either<L, R>

Important traits for Either<L, R>

impl<L, R> Iterator for Either<L, R> where
    L: Iterator,
    R: Iterator<Item = L::Item>,  type Item = L::Item;impl<L, R> Read for Either<L, R> where
    L: Read,
    R: Read, impl<L, R> Write for Either<L, R> where
    L: Write,
    R: Write, 

fn clone(&self) -> Either<L, R>

Returns a copy of the value.

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

Performs copy-assignment from source.

impl<L: Ord, R: Ord> Ord for Either<L, R>

fn cmp(&self, other: &Either<L, R>) -> Ordering

This method returns an Ordering between self and other.

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

Compares and returns the maximum of two values.

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

Compares and returns the minimum of two values.

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

🔬 This is a nightly-only experimental API. (clamp)

Restrict a value to a certain interval.

impl<L, R> From<Result<R, L>> for Either<L, R>

Convert from Result to Either with Ok => Right and Err => Left.

fn from(r: Result<R, L>) -> Self

Performs the conversion.

impl<L, R> Into<Result<R, L>> for Either<L, R>

Convert from Either to Result with Right => Ok and Left => Err.

fn into(self) -> Result<R, L>

Performs the conversion.

impl<L, R, A> Extend<A> for Either<L, R> where
    L: Extend<A>,
    R: Extend<A>, 

fn extend<T>(&mut self, iter: T) where
    T: IntoIterator<Item = A>, 

Extends a collection with the contents of an iterator.

impl<L, R> Display for Either<L, R> where
    L: Display,
    R: Display, 

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

Formats the value using the given formatter.

impl<L: Debug, R: Debug> Debug for Either<L, R>

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

Formats the value using the given formatter.

impl<L, R> Deref for Either<L, R> where
    L: Deref,
    R: Deref<Target = L::Target>, 

type Target = L::Target

The resulting type after dereferencing.

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

Dereferences the value.

impl<L: Hash, R: Hash> Hash for Either<L, R>

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

Feeds this value into the given [Hasher].

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

Feeds a slice of this type into the given [Hasher].

impl<L, R> DerefMut for Either<L, R> where
    L: DerefMut,
    R: DerefMut<Target = L::Target>, 

fn deref_mut(&mut self) -> &mut Self::Target

Mutably dereferences the value.

impl<L, R> Read for Either<L, R> where
    L: Read,
    R: Read, 

Either<L, R> implements Read if both L and R do.

Requires crate feature "use_std"

fn read(&mut self, buf: &mut [u8]) -> Result<usize>

Pull some bytes from this source into the specified buffer, returning how many bytes were read.

fn read_to_end(&mut self, buf: &mut Vec<u8>) -> Result<usize>

Read all bytes until EOF in this source, placing them into buf.

default fn read_vectored(
    &mut self,
    bufs: &mut [IoVecMut]
) -> Result<usize, Error>

🔬 This is a nightly-only experimental API. (iovec)

Like read, except that it reads into a slice of buffers.

unsafe default fn initializer(&self) -> Initializer

🔬 This is a nightly-only experimental API. (read_initializer)

Determines if this Reader can work with buffers of uninitialized memory.

default fn read_to_string(&mut self, buf: &mut String) -> Result<usize, Error>

Read all bytes until EOF in this source, appending them to buf.

default fn read_exact(&mut self, buf: &mut [u8]) -> Result<(), Error>

Read the exact number of bytes required to fill buf.

default fn by_ref(&mut self) -> &mut Self

Creates a "by reference" adaptor for this instance of Read.

default fn bytes(self) -> Bytes<Self>

Transforms this Read instance to an [Iterator] over its bytes.

default fn chain<R>(self, next: R) -> Chain<Self, R> where
    R: Read, 

Creates an adaptor which will chain this stream with another.

default fn take(self, limit: u64) -> Take<Self>

Creates an adaptor which will read at most limit bytes from it.

impl<L, R> Write for Either<L, R> where
    L: Write,
    R: Write, 

Either<L, R> implements Write if both L and R do.

Requires crate feature "use_std"

fn write(&mut self, buf: &[u8]) -> Result<usize>

Write a buffer into this writer, returning how many bytes were written.

fn flush(&mut self) -> Result<()>

Flush this output stream, ensuring that all intermediately buffered contents reach their destination.

default fn write_vectored(&mut self, bufs: &[IoVec]) -> Result<usize, Error>

🔬 This is a nightly-only experimental API. (iovec)

Like write, except that it writes from a slice of buffers.

default fn write_all(&mut self, buf: &[u8]) -> Result<(), Error>

Attempts to write an entire buffer into this writer.

default fn write_fmt(&mut self, fmt: Arguments) -> Result<(), Error>

Writes a formatted string into this writer, returning any error encountered.

default fn by_ref(&mut self) -> &mut Self

Creates a "by reference" adaptor for this instance of Write.

impl<L, R> BufRead for Either<L, R> where
    L: BufRead,
    R: BufRead, 

Requires crate feature "use_std"

fn fill_buf(&mut self) -> Result<&[u8]>

Returns the contents of the internal buffer, filling it with more data from the inner reader if it is empty.

fn consume(&mut self, amt: usize)

Tells this buffer that amt bytes have been consumed from the buffer, so they should no longer be returned in calls to read.

default fn read_until(
    &mut self,
    byte: u8,
    buf: &mut Vec<u8>
) -> Result<usize, Error>

Read all bytes into buf until the delimiter byte or EOF is reached.

default fn read_line(&mut self, buf: &mut String) -> Result<usize, Error>

Read all bytes until a newline (the 0xA byte) is reached, and append them to the provided buffer.

default fn split(self, byte: u8) -> Split<Self>

Returns an iterator over the contents of this reader split on the byte byte.

default fn lines(self) -> Lines<Self>

Returns an iterator over the lines of this reader.

impl<L, R> Error for Either<L, R> where
    L: Error,
    R: Error, 

Either implements Error if both L and R implement it.

fn description(&self) -> &str

This method is soft-deprecated.

fn cause(&self) -> Option<&dyn Error>

Deprecated since 1.33.0:

replaced by Error::source, which can support downcasting

The lower-level cause of this error, if any.

default fn source(&self) -> Option<&(dyn Error + 'static)>

The lower-level source of this error, if any.

default fn type_id(&self) -> TypeId where
    Self: 'static, 

Gets the TypeId of self