Enum itertools::Either
[−]
[src]
pub enum Either<L, R> { Left(L), Right(R), }
Either
represents an alternative holding one value out of
either of the two possible values.
Either
is a general purpose sum type of two parts. For representing
success or error, use the regular Result<T, E>
instead.
Variants
Left(L)
A value of type L
.
Right(R)
A value of type R
.
Methods
impl<L, R> Either<L, R>
[src]
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);
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);
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);
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));
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"));
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));
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"));
fn map_left<F, M>(self, f: F) -> Either<M, R> where
F: FnOnce(L) -> M,
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));
fn map_right<F, S>(self, f: F) -> Either<L, S> where
F: FnOnce(R) -> S,
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));
fn either<F, G, T>(self, f: F, g: G) -> T where
F: FnOnce(L) -> T,
G: FnOnce(R) -> T,
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);
fn left_and_then<F, S>(self, f: F) -> Either<S, R> where
F: FnOnce(L) -> Either<S, R>,
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));
fn right_and_then<F, S>(self, f: F) -> Either<L, S> where
F: FnOnce(R) -> Either<L, S>,
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));
Trait Implementations
impl<L, R> Into<Result<R, L>> for Either<L, R>
[src]
Convert from Either
to Result
with Right => Ok
and Left => Err
.
impl<L, R> Clone for Either<L, R> where
L: Clone,
R: Clone,
[src]
L: Clone,
R: Clone,
fn clone(&self) -> Either<L, R>
Returns a copy of the value. Read more
fn clone_from(&mut self, source: &Self)
1.0.0
Performs copy-assignment from source
. Read more
impl<L, R> Deref for Either<L, R> where
L: Deref,
R: Deref<Target = <L as Deref>::Target>,
[src]
L: Deref,
R: Deref<Target = <L as Deref>::Target>,
impl<L, R> Hash for Either<L, R> where
L: Hash,
R: Hash,
[src]
L: Hash,
R: Hash,
fn hash<__HLR>(&self, __arg_0: &mut __HLR) where
__HLR: Hasher,
__HLR: Hasher,
Feeds this value into the given [Hasher
]. Read more
fn hash_slice<H>(data: &[Self], state: &mut H) where
H: Hasher,
1.3.0
H: Hasher,
Feeds a slice of this type into the given [Hasher
]. Read more
impl<L, R> Iterator for Either<L, R> where
L: Iterator,
R: Iterator<Item = <L as Iterator>::Item>,
[src]
L: Iterator,
R: Iterator<Item = <L as Iterator>::Item>,
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.
fn next(&mut self) -> Option<<Either<L, R> as Iterator>::Item>
Advances the iterator and returns the next value. Read more
fn size_hint(&self) -> (usize, Option<usize>)
Returns the bounds on the remaining length of the iterator. Read more
fn fold<Acc, G>(self, init: Acc, f: G) -> Acc where
G: FnMut(Acc, <Either<L, R> as Iterator>::Item) -> Acc,
G: FnMut(Acc, <Either<L, R> as Iterator>::Item) -> Acc,
An iterator adaptor that applies a function, producing a single, final value. Read more
fn count(self) -> usize
Consumes the iterator, counting the number of iterations and returning it. Read more
fn last(self) -> Option<<Either<L, R> as Iterator>::Item>
Consumes the iterator, returning the last element. Read more
fn nth(&mut self, n: usize) -> Option<<Either<L, R> as Iterator>::Item>
Returns the n
th element of the iterator. Read more
fn collect<B>(self) -> B where
B: FromIterator<<Either<L, R> as Iterator>::Item>,
B: FromIterator<<Either<L, R> as Iterator>::Item>,
Transforms an iterator into a collection. Read more
fn all<F>(&mut self, f: F) -> bool where
F: FnMut(<Either<L, R> as Iterator>::Item) -> bool,
F: FnMut(<Either<L, R> as Iterator>::Item) -> bool,
Tests if every element of the iterator matches a predicate. Read more
fn step_by(self, step: usize) -> StepBy<Self>
🔬 This is a nightly-only experimental API. (iterator_step_by
)
unstable replacement of Range::step_by
Creates an iterator starting at the same point, but stepping by the given amount at each iteration. Read more
fn chain<U>(self, other: U) -> Chain<Self, <U as IntoIterator>::IntoIter> where
U: IntoIterator<Item = Self::Item>,
1.0.0
U: IntoIterator<Item = Self::Item>,
Takes two iterators and creates a new iterator over both in sequence. Read more
fn zip<U>(self, other: U) -> Zip<Self, <U as IntoIterator>::IntoIter> where
U: IntoIterator,
1.0.0
U: IntoIterator,
'Zips up' two iterators into a single iterator of pairs. Read more
fn map<B, F>(self, f: F) -> Map<Self, F> where
F: FnMut(Self::Item) -> B,
1.0.0
F: FnMut(Self::Item) -> B,
Takes a closure and creates an iterator which calls that closure on each element. Read more
fn for_each<F>(self, f: F) where
F: FnMut(Self::Item) -> (),
F: FnMut(Self::Item) -> (),
iterator_for_each
)Calls a closure on each element of an iterator. Read more
fn filter<P>(self, predicate: P) -> Filter<Self, P> where
P: FnMut(&Self::Item) -> bool,
1.0.0
P: FnMut(&Self::Item) -> bool,
Creates an iterator which uses a closure to determine if an element should be yielded. Read more
fn filter_map<B, F>(self, f: F) -> FilterMap<Self, F> where
F: FnMut(Self::Item) -> Option<B>,
1.0.0
F: FnMut(Self::Item) -> Option<B>,
Creates an iterator that both filters and maps. Read more
fn enumerate(self) -> Enumerate<Self>
1.0.0
Creates an iterator which gives the current iteration count as well as the next value. Read more
fn peekable(self) -> Peekable<Self>
1.0.0
Creates an iterator which can use peek
to look at the next element of the iterator without consuming it. Read more
fn skip_while<P>(self, predicate: P) -> SkipWhile<Self, P> where
P: FnMut(&Self::Item) -> bool,
1.0.0
P: FnMut(&Self::Item) -> bool,
Creates an iterator that [skip
]s elements based on a predicate. Read more
fn take_while<P>(self, predicate: P) -> TakeWhile<Self, P> where
P: FnMut(&Self::Item) -> bool,
1.0.0
P: FnMut(&Self::Item) -> bool,
Creates an iterator that yields elements based on a predicate. Read more
fn skip(self, n: usize) -> Skip<Self>
1.0.0
Creates an iterator that skips the first n
elements. Read more
fn take(self, n: usize) -> Take<Self>
1.0.0
Creates an iterator that yields its first n
elements. Read more
fn scan<St, B, F>(self, initial_state: St, f: F) -> Scan<Self, St, F> where
F: FnMut(&mut St, Self::Item) -> Option<B>,
1.0.0
F: FnMut(&mut St, Self::Item) -> Option<B>,
An iterator adaptor similar to [fold
] that holds internal state and produces a new iterator. Read more
fn flat_map<U, F>(self, f: F) -> FlatMap<Self, U, F> where
F: FnMut(Self::Item) -> U,
U: IntoIterator,
1.0.0
F: FnMut(Self::Item) -> U,
U: IntoIterator,
Creates an iterator that works like map, but flattens nested structure. Read more
fn fuse(self) -> Fuse<Self>
1.0.0
Creates an iterator which ends after the first [None
]. Read more
fn inspect<F>(self, f: F) -> Inspect<Self, F> where
F: FnMut(&Self::Item) -> (),
1.0.0
F: FnMut(&Self::Item) -> (),
Do something with each element of an iterator, passing the value on. Read more
fn by_ref(&mut self) -> &mut Self
1.0.0
Borrows an iterator, rather than consuming it. Read more
fn partition<B, F>(self, f: F) -> (B, B) where
B: Default + Extend<Self::Item>,
F: FnMut(&Self::Item) -> bool,
1.0.0
B: Default + Extend<Self::Item>,
F: FnMut(&Self::Item) -> bool,
Consumes an iterator, creating two collections from it. Read more
fn any<F>(&mut self, f: F) -> bool where
F: FnMut(Self::Item) -> bool,
1.0.0
F: FnMut(Self::Item) -> bool,
Tests if any element of the iterator matches a predicate. Read more
fn find<P>(&mut self, predicate: P) -> Option<Self::Item> where
P: FnMut(&Self::Item) -> bool,
1.0.0
P: FnMut(&Self::Item) -> bool,
Searches for an element of an iterator that satisfies a predicate. Read more
fn position<P>(&mut self, predicate: P) -> Option<usize> where
P: FnMut(Self::Item) -> bool,
1.0.0
P: FnMut(Self::Item) -> bool,
Searches for an element in an iterator, returning its index. Read more
fn rposition<P>(&mut self, predicate: P) -> Option<usize> where
P: FnMut(Self::Item) -> bool,
Self: ExactSizeIterator + DoubleEndedIterator,
1.0.0
P: FnMut(Self::Item) -> bool,
Self: ExactSizeIterator + DoubleEndedIterator,
Searches for an element in an iterator from the right, returning its index. Read more
fn max(self) -> Option<Self::Item> where
Self::Item: Ord,
1.0.0
Self::Item: Ord,
Returns the maximum element of an iterator. Read more
fn min(self) -> Option<Self::Item> where
Self::Item: Ord,
1.0.0
Self::Item: Ord,
Returns the minimum element of an iterator. Read more
fn max_by_key<B, F>(self, f: F) -> Option<Self::Item> where
B: Ord,
F: FnMut(&Self::Item) -> B,
1.6.0
B: Ord,
F: FnMut(&Self::Item) -> B,
Returns the element that gives the maximum value from the specified function. Read more
fn max_by<F>(self, compare: F) -> Option<Self::Item> where
F: FnMut(&Self::Item, &Self::Item) -> Ordering,
1.15.0
F: FnMut(&Self::Item, &Self::Item) -> Ordering,
Returns the element that gives the maximum value with respect to the specified comparison function. Read more
fn min_by_key<B, F>(self, f: F) -> Option<Self::Item> where
B: Ord,
F: FnMut(&Self::Item) -> B,
1.6.0
B: Ord,
F: FnMut(&Self::Item) -> B,
Returns the element that gives the minimum value from the specified function. Read more
fn min_by<F>(self, compare: F) -> Option<Self::Item> where
F: FnMut(&Self::Item, &Self::Item) -> Ordering,
1.15.0
F: FnMut(&Self::Item, &Self::Item) -> Ordering,
Returns the element that gives the minimum value with respect to the specified comparison function. Read more
fn rev(self) -> Rev<Self> where
Self: DoubleEndedIterator,
1.0.0
Self: DoubleEndedIterator,
Reverses an iterator's direction. Read more
fn unzip<A, B, FromA, FromB>(self) -> (FromA, FromB) where
FromA: Default + Extend<A>,
FromB: Default + Extend<B>,
Self: Iterator<Item = (A, B)>,
1.0.0
FromA: Default + Extend<A>,
FromB: Default + Extend<B>,
Self: Iterator<Item = (A, B)>,
Converts an iterator of pairs into a pair of containers. Read more
fn cloned<'a, T>(self) -> Cloned<Self> where
Self: Iterator<Item = &'a T>,
T: 'a + Clone,
1.0.0
Self: Iterator<Item = &'a T>,
T: 'a + Clone,
Creates an iterator which [clone
]s all of its elements. Read more
fn cycle(self) -> Cycle<Self> where
Self: Clone,
1.0.0
Self: Clone,
Repeats an iterator endlessly. Read more
fn sum<S>(self) -> S where
S: Sum<Self::Item>,
1.11.0
S: Sum<Self::Item>,
Sums the elements of an iterator. Read more
fn product<P>(self) -> P where
P: Product<Self::Item>,
1.11.0
P: Product<Self::Item>,
Iterates over the entire iterator, multiplying all the elements Read more
fn cmp<I>(self, other: I) -> Ordering where
I: IntoIterator<Item = Self::Item>,
Self::Item: Ord,
1.5.0
I: IntoIterator<Item = Self::Item>,
Self::Item: Ord,
Lexicographically compares the elements of this Iterator
with those of another. Read more
fn partial_cmp<I>(self, other: I) -> Option<Ordering> where
I: IntoIterator,
Self::Item: PartialOrd<<I as IntoIterator>::Item>,
1.5.0
I: IntoIterator,
Self::Item: PartialOrd<<I as IntoIterator>::Item>,
Lexicographically compares the elements of this Iterator
with those of another. Read more
fn eq<I>(self, other: I) -> bool where
I: IntoIterator,
Self::Item: PartialEq<<I as IntoIterator>::Item>,
1.5.0
I: IntoIterator,
Self::Item: PartialEq<<I as IntoIterator>::Item>,
Determines if the elements of this Iterator
are equal to those of another. Read more
fn ne<I>(self, other: I) -> bool where
I: IntoIterator,
Self::Item: PartialEq<<I as IntoIterator>::Item>,
1.5.0
I: IntoIterator,
Self::Item: PartialEq<<I as IntoIterator>::Item>,
Determines if the elements of this Iterator
are unequal to those of another. Read more
fn lt<I>(self, other: I) -> bool where
I: IntoIterator,
Self::Item: PartialOrd<<I as IntoIterator>::Item>,
1.5.0
I: IntoIterator,
Self::Item: PartialOrd<<I as IntoIterator>::Item>,
Determines if the elements of this Iterator
are lexicographically less than those of another. Read more
fn le<I>(self, other: I) -> bool where
I: IntoIterator,
Self::Item: PartialOrd<<I as IntoIterator>::Item>,
1.5.0
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. Read more
fn gt<I>(self, other: I) -> bool where
I: IntoIterator,
Self::Item: PartialOrd<<I as IntoIterator>::Item>,
1.5.0
I: IntoIterator,
Self::Item: PartialOrd<<I as IntoIterator>::Item>,
Determines if the elements of this Iterator
are lexicographically greater than those of another. Read more
fn ge<I>(self, other: I) -> bool where
I: IntoIterator,
Self::Item: PartialOrd<<I as IntoIterator>::Item>,
1.5.0
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. Read more
impl<L, R> DoubleEndedIterator for Either<L, R> where
L: DoubleEndedIterator,
R: DoubleEndedIterator<Item = <L as Iterator>::Item>,
[src]
L: DoubleEndedIterator,
R: DoubleEndedIterator<Item = <L as Iterator>::Item>,
fn next_back(&mut self) -> Option<<Either<L, R> as Iterator>::Item>
Removes and returns an element from the end of the iterator. Read more
fn rfind<P>(&mut self, predicate: P) -> Option<Self::Item> where
P: FnMut(&Self::Item) -> bool,
P: FnMut(&Self::Item) -> bool,
iter_rfind
)Searches for an element of an iterator from the right that satisfies a predicate. Read more
impl<L, R> Eq for Either<L, R> where
L: Eq,
R: Eq,
[src]
L: Eq,
R: Eq,
impl<L, R> PartialEq<Either<L, R>> for Either<L, R> where
L: PartialEq<L>,
R: PartialEq<R>,
[src]
L: PartialEq<L>,
R: PartialEq<R>,
fn eq(&self, __arg_0: &Either<L, R>) -> bool
This method tests for self
and other
values to be equal, and is used by ==
. Read more
fn ne(&self, __arg_0: &Either<L, R>) -> bool
This method tests for !=
.
impl<L, R, Target> AsMut<Target> for Either<L, R> where
L: AsMut<Target>,
R: AsMut<Target>,
[src]
L: AsMut<Target>,
R: AsMut<Target>,
fn as_mut(&mut self) -> &mut Target
Performs the conversion.
impl<L, R> Display for Either<L, R> where
L: Display,
R: Display,
[src]
L: Display,
R: Display,
fn fmt(&self, f: &mut Formatter) -> Result<(), Error>
Formats the value using the given formatter. Read more
impl<L, R> From<Result<R, L>> for Either<L, R>
[src]
Convert from Result
to Either
with Ok => Right
and Err => Left
.
impl<L, R> Ord for Either<L, R> where
L: Ord,
R: Ord,
[src]
L: Ord,
R: Ord,
fn cmp(&self, __arg_0: &Either<L, R>) -> Ordering
This method returns an Ordering
between self
and other
. Read more
fn max(self, other: Self) -> Self
ord_max_min
)Compares and returns the maximum of two values. Read more
fn min(self, other: Self) -> Self
ord_max_min
)Compares and returns the minimum of two values. Read more
impl<L, R> PartialOrd<Either<L, R>> for Either<L, R> where
L: PartialOrd<L>,
R: PartialOrd<R>,
[src]
L: PartialOrd<L>,
R: PartialOrd<R>,
fn partial_cmp(&self, __arg_0: &Either<L, R>) -> Option<Ordering>
This method returns an ordering between self
and other
values if one exists. Read more
fn lt(&self, __arg_0: &Either<L, R>) -> bool
This method tests less than (for self
and other
) and is used by the <
operator. Read more
fn le(&self, __arg_0: &Either<L, R>) -> bool
This method tests less than or equal to (for self
and other
) and is used by the <=
operator. Read more
fn gt(&self, __arg_0: &Either<L, R>) -> bool
This method tests greater than (for self
and other
) and is used by the >
operator. Read more
fn ge(&self, __arg_0: &Either<L, R>) -> bool
This method tests greater than or equal to (for self
and other
) and is used by the >=
operator. Read more
impl<L, R> Copy for Either<L, R> where
L: Copy,
R: Copy,
[src]
L: Copy,
R: Copy,
impl<L, R, A> Extend<A> for Either<L, R> where
L: Extend<A>,
R: Extend<A>,
[src]
L: Extend<A>,
R: Extend<A>,
fn extend<T>(&mut self, iter: T) where
T: IntoIterator<Item = A>,
T: IntoIterator<Item = A>,
Extends a collection with the contents of an iterator. Read more
impl<L, R> ExactSizeIterator for Either<L, R> where
L: ExactSizeIterator,
R: ExactSizeIterator<Item = <L as Iterator>::Item>,
[src]
L: ExactSizeIterator,
R: ExactSizeIterator<Item = <L as Iterator>::Item>,
fn len(&self) -> usize
1.0.0
Returns the exact number of times the iterator will iterate. Read more
fn is_empty(&self) -> bool
exact_size_is_empty
)Returns whether the iterator is empty. Read more
impl<L, R, Target> AsRef<Target> for Either<L, R> where
L: AsRef<Target>,
R: AsRef<Target>,
[src]
L: AsRef<Target>,
R: AsRef<Target>,
fn as_ref(&self) -> &Target
Performs the conversion.
impl<L, R> DerefMut for Either<L, R> where
L: DerefMut,
R: DerefMut<Target = <L as Deref>::Target>,
[src]
L: DerefMut,
R: DerefMut<Target = <L as Deref>::Target>,
impl<L, R> Debug for Either<L, R> where
L: Debug,
R: Debug,
[src]
L: Debug,
R: Debug,