Enum itertools::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.

Implementations

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));

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"));

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));

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"));

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));

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]);

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));

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));

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

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]));

pub fn left_or(self, other: L) -> L

Return left value or given value

Arguments passed to left_or are eagerly evaluated; if you are passing the result of a function call, it is recommended to use left_or_else, which is lazily evaluated.

Examples

let left: Either<&str, &str> = Left("left");
assert_eq!(left.left_or("foo"), "left");

let right: Either<&str, &str> = Right("right");
assert_eq!(right.left_or("left"), "left");

pub fn left_or_default(self) -> L where
    L: Default, 

Return left or a default

Examples

let left: Either<String, u32> = Left("left".to_string());
assert_eq!(left.left_or_default(), "left");

let right: Either<String, u32> = Right(42);
assert_eq!(right.left_or_default(), String::default());

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

Returns left value or computes it from a closure

Examples

let left: Either<String, u32> = Left("3".to_string());
assert_eq!(left.left_or_else(|_| unreachable!()), "3");

let right: Either<String, u32> = Right(3);
assert_eq!(right.left_or_else(|x| x.to_string()), "3");

pub fn right_or(self, other: R) -> R

Return right value or given value

Arguments passed to right_or are eagerly evaluated; if you are passing the result of a function call, it is recommended to use right_or_else, which is lazily evaluated.

Examples

let right: Either<&str, &str> = Right("right");
assert_eq!(right.right_or("foo"), "right");

let left: Either<&str, &str> = Left("left");
assert_eq!(left.right_or("right"), "right");

pub fn right_or_default(self) -> R where
    R: Default, 

Return right or a default

Examples

let left: Either<String, u32> = Left("left".to_string());
assert_eq!(left.right_or_default(), u32::default());

let right: Either<String, u32> = Right(42);
assert_eq!(right.right_or_default(), 42);

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

Returns right value or computes it from a closure

Examples

let left: Either<String, u32> = Left("3".to_string());
assert_eq!(left.right_or_else(|x| x.parse().unwrap()), 3);

let right: Either<String, u32> = Right(3);
assert_eq!(right.right_or_else(|_| unreachable!()), 3);

pub fn unwrap_left(self) -> L where
    R: Debug, 

Returns the left value

Examples

let left: Either<_, ()> = Left(3);
assert_eq!(left.unwrap_left(), 3);

Panics

When Either is a Right value

let right: Either<(), _> = Right(3);
right.unwrap_left();

pub fn unwrap_right(self) -> R where
    L: Debug, 

Returns the right value

Examples

let right: Either<(), _> = Right(3);
assert_eq!(right.unwrap_right(), 3);

Panics

When Either is a Left value

let left: Either<_, ()> = Left(3);
left.unwrap_right();

pub fn expect_left(self, msg: &str) -> L where
    R: Debug, 

Returns the left value

Examples

let left: Either<_, ()> = Left(3);
assert_eq!(left.expect_left("value was Right"), 3);

Panics

When Either is a Right value

let right: Either<(), _> = Right(3);
right.expect_left("value was Right");

pub fn expect_right(self, msg: &str) -> R where
    L: Debug, 

Returns the right value

Examples

let right: Either<(), _> = Right(3);
assert_eq!(right.expect_right("value was Left"), 3);

Panics

When Either is a Left value

let left: Either<_, ()> = Left(3);
left.expect_right("value was Right");

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);

pub fn map<F, M>(self, f: F) -> Either<M, M> where
    F: FnOnce(T) -> M, 

Map f over the contained value and return the result in the corresponding variant.

use either::*;

let value: Either<_, i32> = Right(42);

let other = value.map(|x| x * 2);
assert_eq!(other, Right(84));

Trait Implementations

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

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

Performs the conversion.

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

Requires crate feature use_std.

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

Performs the conversion.

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

Requires crate feature use_std.

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

Performs the conversion.

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

Requires crate feature use_std.

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

Performs the conversion.

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

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

Performs the conversion.

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

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

Performs the conversion.

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

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

Performs the conversion.

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

Requires crate feature use_std.

pub fn as_ref(&self) -> &CStr

Performs the conversion.

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

Requires crate feature use_std.

pub fn as_ref(&self) -> &OsStr

Performs the conversion.

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

Requires crate feature use_std.

pub fn as_ref(&self) -> &Path

Performs the conversion.

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

pub fn as_ref(&self) -> &Target

Performs the conversion.

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

pub fn as_ref(&self) -> &str

Performs the conversion.

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

Requires crate feature "use_std"

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

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

pub 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.

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

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

pub 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.

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

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

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

Returns an iterator over the lines of this reader.

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

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

Returns a copy of the value.

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

Performs copy-assignment from source.

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

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

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

Formats the value using the given formatter.

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

type Target = <L as Deref>::Target

The resulting type after dereferencing.

pub fn deref(&self) -> &<Either<L, R> as Deref>::Target

Dereferences the value.

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

pub fn deref_mut(&mut self) -> &mut <Either<L, R> as Deref>::Target

Mutably dereferences the value.

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

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

Formats the value using the given formatter.

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

pub fn next_back(&mut self) -> Option<<Either<L, R> as Iterator>::Item>

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

pub fn advance_back_by(&mut self, n: usize) -> Result<(), usize>

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

recently added

Advances the iterator from the back by n elements.

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

Returns the nth element from the end of the iterator.

pub 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 Iterator::try_fold(): it takes elements starting from the back of the iterator.

pub fn rfold<B, F>(self, init: 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.

pub 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, R> Eq for Either<L, R> where
    R: Eq,
    L: Eq, 

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

Either implements Error if both L and R implement it.

pub fn description(&self) -> &str

👎 Deprecated since 1.42.0:

use the Display impl or to_string()

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

👎 Deprecated since 1.33.0:

replaced by Error::source, which can support downcasting

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

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

pub fn backtrace(&self) -> Option<&Backtrace>

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

Returns a stack backtrace, if available, of where this error occurred.

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

pub fn len(&self) -> usize

Returns the exact length of the iterator.

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

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

Extends a collection with the contents of an iterator.

pub fn extend_one(&mut self, item: A)

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

Extends a collection with exactly one element.

pub fn extend_reserve(&mut self, additional: usize)

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

Reserves capacity in a collection for the given number of additional elements.

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

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

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

Performs the conversion.

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

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

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

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

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

Performs the conversion.

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

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

type Item = <L as Iterator>::Item

The type of the elements being iterated over.

pub fn next(&mut self) -> Option<<Either<L, R> as Iterator>::Item>

Advances the iterator and returns the next value.

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

Returns the bounds on the remaining length of the iterator.

pub fn fold<Acc, G>(self, init: Acc, f: G) -> Acc where
    G: FnMut(Acc, <Either<L, R> as Iterator>::Item) -> Acc, 

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

pub fn count(self) -> usize

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

pub fn last(self) -> Option<<Either<L, R> as Iterator>::Item>

Consumes the iterator, returning the last element.

pub fn nth(&mut self, n: usize) -> Option<<Either<L, R> as Iterator>::Item>

Returns the nth element of the iterator.

pub fn collect<B>(self) -> B where
    B: FromIterator<<Either<L, R> as Iterator>::Item>, 

Transforms an iterator into a collection.

pub fn all<F>(&mut self, f: F) -> bool where
    F: FnMut(<Either<L, R> as Iterator>::Item) -> bool, 

Tests if every element of the iterator matches a predicate.

pub fn advance_by(&mut self, n: usize) -> Result<(), usize>

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

recently added

Advances the iterator by n elements.

pub 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.

pub 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.

pub 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.

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

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

recently added

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

pub fn intersperse_with<G>(self, separator: G) -> IntersperseWith<Self, G> where
    G: FnMut() -> Self::Item, 

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

recently added

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

pub 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.

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

Calls a closure on each element of an iterator.

pub 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.

pub 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.

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

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

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

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

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

Creates an iterator that skips elements based on a predicate.

pub 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.

pub fn map_while<B, P>(self, predicate: P) -> MapWhile<Self, P> where
    P: FnMut(Self::Item) -> Option<B>, 

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

recently added

Creates an iterator that both yields elements based on a predicate and maps.

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

Creates an iterator that skips the first n elements.

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

Creates an iterator that yields its first n elements.

pub 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.

pub 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.

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

Creates an iterator that flattens nested structure.

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

Creates an iterator which ends after the first None.

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

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

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

Borrows an iterator, rather than consuming it.

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

Consumes an iterator, creating two collections from it.

pub fn partition_in_place<'a, T, P>(self, predicate: P) -> usize where
    Self: DoubleEndedIterator<Item = &'a mut T>,
    T: 'a,
    P: FnMut(&T) -> bool, 

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

new API

Reorders the elements of this iterator in-place according to the given predicate, such that all those that return true precede all those that return false. Returns the number of true elements found.

pub fn is_partitioned<P>(self, predicate: P) -> bool where
    P: FnMut(Self::Item) -> bool, 

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

new API

Checks if the elements of this iterator are partitioned according to the given predicate, such that all those that return true precede all those that return false.

pub 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.

pub 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.

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

Reduces the elements to a single one, by repeatedly applying a reducing operation.

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

Tests if any element of the iterator matches a predicate.

pub 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.

pub 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.

pub fn try_find<F, R>(
    &mut self,
    f: F
) -> Result<Option<Self::Item>, <R as Try>::Error> where
    F: FnMut(&Self::Item) -> R,
    R: Try<Ok = bool>, 

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

new API

Applies function to the elements of iterator and returns the first true result or the first error.

pub 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.

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

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

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

Returns the maximum element of an iterator.

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

Returns the minimum element of an iterator.

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

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

pub 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.

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

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

pub 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.

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

Reverses an iterator’s direction.

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

Converts an iterator of pairs into a pair of containers.

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

Creates an iterator which copies all of its elements.

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

Creates an iterator which clones all of its elements.

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

Repeats an iterator endlessly.

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

Sums the elements of an iterator.

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

Iterates over the entire iterator, multiplying all the elements

pub 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.

pub fn cmp_by<I, F>(self, other: I, cmp: F) -> Ordering where
    I: IntoIterator,
    F: FnMut(Self::Item, <I as IntoIterator>::Item) -> Ordering, 

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

Lexicographically compares the elements of this Iterator with those of another with respect to the specified comparison function.

pub 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.

pub fn partial_cmp_by<I, F>(self, other: I, partial_cmp: F) -> Option<Ordering> where
    I: IntoIterator,
    F: FnMut(Self::Item, <I as IntoIterator>::Item) -> Option<Ordering>, 

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

Lexicographically compares the elements of this Iterator with those of another with respect to the specified comparison function.

pub 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.

pub fn eq_by<I, F>(self, other: I, eq: F) -> bool where
    I: IntoIterator,
    F: FnMut(Self::Item, <I as IntoIterator>::Item) -> bool, 

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

Determines if the elements of this Iterator are equal to those of another with respect to the specified equality function.

pub 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.

pub 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.

pub 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.

pub 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.

pub 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.

pub 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.

pub 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.

pub fn is_sorted_by_key<F, K>(self, f: F) -> bool where
    K: PartialOrd<K>,
    F: FnMut(Self::Item) -> 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> Ord for Either<L, R> where
    R: Ord,
    L: Ord, 

pub fn cmp(&self, other: &Either<L, R>) -> 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<L, R> PartialEq<Either<L, R>> for Either<L, R> where
    R: PartialEq<R>,
    L: PartialEq<L>, 

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

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

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

This method tests for !=.

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

pub fn partial_cmp(&self, other: &Either<L, R>) -> 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<L, R> Read for Either<L, R> where
    R: Read,
    L: Read, 

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

Requires crate feature "use_std"

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

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

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

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

pub fn read_vectored(
    &mut self,
    bufs: &mut [IoSliceMut<'_>]
) -> Result<usize, Error>

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

pub fn is_read_vectored(&self) -> bool

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

Determines if this Reader has an efficient read_vectored implementation.

pub unsafe fn initializer(&self) -> Initializer

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

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

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

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

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

Read the exact number of bytes required to fill buf.

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

Creates a “by reference” adaptor for this instance of Read.

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

Transforms this Read instance to an Iterator over its bytes.

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

Creates an adaptor which will chain this stream with another.

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

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

impl<L, R> StructuralEq for Either<L, R>

impl<L, R> StructuralPartialEq for Either<L, R>

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

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

Requires crate feature "use_std"

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

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

pub fn flush(&mut self) -> Result<(), Error>

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

pub fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> Result<usize, Error>

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

pub fn is_write_vectored(&self) -> bool

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

Determines if this Writer has an efficient write_vectored implementation.

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

Attempts to write an entire buffer into this writer.

pub fn write_all_vectored(
    &mut self,
    bufs: &mut [IoSlice<'_>]
) -> Result<(), Error>

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

Attempts to write multiple buffers into this writer.

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

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

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

Creates a “by reference” adaptor for this instance of Write.