[−][src]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

A value of type L.

A value of type R.

Methods

impl<L, R> Either<L, R>
[src]

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);

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);

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);

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>

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>

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>

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>

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>

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));

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);

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>

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>

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>

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)>
[src]

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)>
[src]

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>
[src]

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, R> Clone for Either<L, R> where
    L: Clone,
    R: Clone, 
[src]

ⓘImportant traits for Either<L, R>

Returns a copy of the value. Read more

Performs copy-assignment from source. Read more

impl<L, R> Copy for Either<L, R> where
    L: Copy,
    R: Copy, 
[src]

impl<L, R> Display for Either<L, R> where
    L: Display,
    R: Display, 
[src]

Formats the value using the given formatter. Read more

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

Extends a collection with the contents of an iterator. Read more

impl<L, R> Into<Result<R, L>> for Either<L, R>
[src]

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

Performs the conversion.

impl<L, R> PartialOrd<Either<L, R>> for Either<L, R> where
    L: PartialOrd<L>,
    R: PartialOrd<R>, 
[src]

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

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

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

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

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

ⓘImportant traits for Either<L, R>

Performs the conversion.

impl<L, R> Hash for Either<L, R> where
    L: Hash,
    R: Hash, 
[src]

Feeds this value into the given [Hasher]. Read more

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

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

ⓘImportant traits for &'a mut R

Performs the conversion.

impl<L, R> Debug for Either<L, R> where
    L: Debug,
    R: Debug, 
[src]

Formats the value using the given formatter. Read more

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

The resulting type after dereferencing.

ⓘImportant traits for Either<L, R>

Dereferences the value.

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

ⓘImportant traits for &'a mut R

Performs the conversion.

impl<L, R> PartialEq<Either<L, R>> for Either<L, R> where
    L: PartialEq<L>,
    R: PartialEq<R>, 
[src]

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

This method tests for !=.

impl<L, R> Eq for Either<L, R> where
    L: Eq,
    R: Eq, 
[src]

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

Returns the exact number of times the iterator will iterate. Read more

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

Returns whether the iterator is empty. Read more

impl<L, R> Ord for Either<L, R> where
    L: Ord,
    R: Ord, 
[src]

This method returns an Ordering between self and other. Read more

Compares and returns the maximum of two values. Read more

Compares and returns the minimum of two values. Read more

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

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

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

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

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

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

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

The type of the elements being iterated over.

Advances the iterator and returns the next value. Read more

Returns the bounds on the remaining length of the iterator. Read more

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

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

Consumes the iterator, returning the last element. Read more

Returns the nth element of the iterator. Read more

Transforms an iterator into a collection. Read more

Tests if every element of the iterator matches a predicate. Read more

ⓘImportant traits for StepBy<I>

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

ⓘImportant traits for Chain<A, B>

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

ⓘImportant traits for Zip<A, B>

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

ⓘImportant traits for Map<I, F>

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

Calls a closure on each element of an iterator. Read more

ⓘImportant traits for Filter<I, P>

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

ⓘImportant traits for FilterMap<I, F>

Creates an iterator that both filters and maps. Read more

ⓘImportant traits for Enumerate<I>

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

ⓘImportant traits for Peekable<I>

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

ⓘImportant traits for SkipWhile<I, P>

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

ⓘImportant traits for TakeWhile<I, P>

Creates an iterator that yields elements based on a predicate. Read more

ⓘImportant traits for Skip<I>

Creates an iterator that skips the first n elements. Read more

ⓘImportant traits for Take<I>

Creates an iterator that yields its first n elements. Read more

ⓘImportant traits for Scan<I, St, F>

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

ⓘImportant traits for FlatMap<I, U, F>

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

ⓘImportant traits for Flatten<I>

Creates an iterator that flattens nested structure. Read more

ⓘImportant traits for Fuse<I>

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

ⓘImportant traits for Inspect<I, F>

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

ⓘImportant traits for &'a mut R

Borrows an iterator, rather than consuming it. Read more

Consumes an iterator, creating two collections from it. Read more

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

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

Tests if any element of the iterator matches a predicate. Read more

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

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

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

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

Returns the maximum element of an iterator. Read more

Returns the minimum element of an iterator. Read more

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

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

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

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

ⓘImportant traits for Rev<I>

Reverses an iterator's direction. Read more

Converts an iterator of pairs into a pair of containers. Read more

ⓘImportant traits for Cloned<I>

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

ⓘImportant traits for Cycle<I>

Repeats an iterator endlessly. Read more

Sums the elements of an iterator. Read more

Iterates over the entire iterator, multiplying all the elements Read more

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

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

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

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

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

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

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

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

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

ⓘImportant traits for Either<L, R>

Mutably dereferences the value.

Auto Trait Implementations

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

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

Blanket Implementations

impl<T> Itertools for T where
    T: Iterator + ?Sized, 
[src]

ⓘImportant traits for Interleave<I, J>

Alternate elements from two iterators until both have run out. Read more

ⓘImportant traits for InterleaveShortest<I, J>

Alternate elements from two iterators until at least one of them has run out. Read more

ⓘImportant traits for Intersperse<I>

An iterator adaptor to insert a particular value between each element of the adapted iterator. Read more

ⓘImportant traits for ZipLongest<T, U>

Create an iterator which iterates over both this and the specified iterator simultaneously, yielding pairs of two optional elements. Read more

ⓘImportant traits for ZipEq<I, J>

Create an iterator which iterates over both this and the specified iterator simultaneously, yielding pairs of elements. Read more

ⓘImportant traits for Batching<I, F>

A “meta iterator adaptor”. Its closure recives a reference to the iterator and may pick off as many elements as it likes, to produce the next iterator element. Read more

Return an iterable that can group iterator elements. Consecutive elements that map to the same key (“runs”), are assigned to the same group. Read more

Return an iterable that can chunk the iterator. Read more

ⓘImportant traits for TupleWindows<I, T>

Return an iterator over all contiguous windows producing tuples of a specific size (up to 4). Read more

ⓘImportant traits for Tuples<I, T>

Return an iterator that groups the items in tuples of a specific size (up to 4). Read more

Split into an iterator pair that both yield all elements from the original iterator. Read more

ⓘImportant traits for Step<I>

Return an iterator adaptor that steps n elements in the base iterator for each iteration. Read more

ⓘImportant traits for MapResults<I, F>

Return an iterator adaptor that applies the provided closure to every Result::Ok value. Result::Err values are unchanged. Read more

ⓘImportant traits for Merge<I, J>

Return an iterator adaptor that merges the two base iterators in ascending order. If both base iterators are sorted (ascending), the result is sorted. Read more

ⓘImportant traits for MergeBy<I, J, F>

Return an iterator adaptor that merges the two base iterators in order. This is much like .merge() but allows for a custom ordering. Read more

ⓘImportant traits for KMerge<I>

Return an iterator adaptor that flattens an iterator of iterators by merging them in ascending order. Read more

ⓘImportant traits for KMergeBy<I, F>

Return an iterator adaptor that flattens an iterator of iterators by merging them according to the given closure. Read more

ⓘImportant traits for Product<I, J>

Return an iterator adaptor that iterates over the cartesian product of the element sets of two iterators self and J. Read more

ⓘImportant traits for Coalesce<I, F>

Return an iterator adaptor that uses the passed-in closure to optionally merge together consecutive elements. Read more

ⓘImportant traits for Dedup<I>

Remove duplicates from sections of consecutive identical elements. If the iterator is sorted, all elements will be unique. Read more

ⓘImportant traits for Unique<I>

Return an iterator adaptor that filters out elements that have already been produced once during the iteration. Duplicates are detected using hash and equality. Read more

ⓘImportant traits for UniqueBy<I, V, F>

Return an iterator adaptor that filters out elements that have already been produced once during the iteration. Read more

ⓘImportant traits for PeekingTakeWhile<'a, I, F>

Return an iterator adaptor that borrows from this iterator and takes items while the closure accept returns true. Read more

ⓘImportant traits for TakeWhileRef<'a, I, F>

Return an iterator adaptor that borrows from a Clone-able iterator to only pick off elements while the predicate accept returns true. Read more

ⓘImportant traits for WhileSome<I>

Return an iterator adaptor that filters Option<A> iterator elements and produces A. Stops on the first None encountered. Read more

ⓘImportant traits for TupleCombinations<I, T>

Return an iterator adaptor that iterates over the combinations of the elements from an iterator. Read more

ⓘImportant traits for Combinations<I>

Return an iterator adaptor that iterates over the n-length combinations of the elements from an iterator. Read more

ⓘImportant traits for PadUsing<I, F>

Return an iterator adaptor that pads the sequence to a minimum length of min by filling missing elements using a closure f. Read more

ⓘImportant traits for Flatten<I, J>

Unravel a nested iterator. Read more

ⓘImportant traits for WithPosition<I>

Return an iterator adaptor that wraps each element in a Position to ease special-case handling of the first or last elements. Read more

ⓘImportant traits for Positions<I, F>

Return an iterator adaptor that yields the indices of all elements satisfying a predicate, counted from the start of the iterator. Read more

Advances the iterator and returns the next items grouped in a tuple of a specific size (up to 4). Read more

Find the position and value of the first element satisfying a predicate. Read more

Check whether all elements compare equal. Read more

Consume the first n elements from the iterator eagerly, and return the same iterator again. Read more

Consume the last n elements from the iterator eagerly, and return the same iterator again. Read more

Run the closure f eagerly on each element of the iterator. Read more

Combine all an iterator's elements into one element by using Extend. Read more

ⓘImportant traits for Vec<u8>

.collect_vec() is simply a type specialization of .collect(), for convenience. Read more

Assign to each reference in self from the from iterator, stopping at the shortest of the two iterators. Read more

Combine all iterator elements into one String, seperated by sep. Read more

Format all iterator elements, separated by sep. Read more

Format all iterator elements, separated by sep. Read more

Fold Result values from an iterator. Read more

Fold Option values from an iterator. Read more

Accumulator of the elements in the iterator. Read more

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

ⓘImportant traits for Vec<u8>

Collect all iterator elements into a sorted vector in ascending order. Read more

ⓘImportant traits for Vec<u8>

Collect all iterator elements into a sorted vector. Read more

Collect all iterator elements into one of two partitions. Unlike Iterator::partition, each partition may have a distinct type. Read more

Return the minimum and maximum elements in the iterator. Read more

Return the minimum and maximum element of an iterator, as determined by the specified function. Read more

Return the minimum and maximum element of an iterator, as determined by the specified comparison function. Read more

impl<T> ToOwned for T where
    T: Clone, 
[src]

Creates owned data from borrowed data, usually by cloning. Read more

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

recently added

Uses borrowed data to replace owned data, usually by cloning. Read more

impl<T> From for T
[src]

Performs the conversion.

impl<T> ToString for T where
    T: Display + ?Sized, 
[src]

Converts the given value to a String. Read more

impl<I> IntoIterator for I where
    I: Iterator, 
[src]

The type of the elements being iterated over.

Which kind of iterator are we turning this into?

Creates an iterator from a value. Read more

impl<T, U> Into for T where
    U: From<T>, 
[src]

Performs the conversion.

impl<T, U> TryFrom for T where
    T: From<U>, 
[src]

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

The type returned in the event of a conversion error.

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

Performs the conversion.

impl<T> Borrow for T where
    T: ?Sized, 
[src]

ⓘImportant traits for &'a mut R

Immutably borrows from an owned value. Read more

impl<T, U> TryInto for T where
    U: TryFrom<T>, 
[src]

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

The type returned in the event of a conversion error.

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

Performs the conversion.

impl<T> BorrowMut for T where
    T: ?Sized, 
[src]

ⓘImportant traits for &'a mut R

Mutably borrows from an owned value. Read more

impl<T> Any for T where
    T: 'static + ?Sized, 
[src]

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

this method will likely be replaced by an associated static

Gets the TypeId of self. Read more