Struct core::iter::Flatten

#[must_use = "iterators are lazy and do nothing unless consumed"]pub struct Flatten<I: Iterator<Item: IntoIterator>> { /* fields omitted */ }

An iterator that flattens one level of nesting in an iterator of things that can be turned into iterators.

This struct is created by the flatten method on Iterator. See its documentation for more.

Trait Implementations

impl<I, U> Clone for Flatten<I> where
    I: Clone + Iterator<Item: IntoIterator<IntoIter = U, Item = U::Item>>,
    U: Clone + Iterator, 

pub fn clone(&self) -> Self

Returns a copy of the value.

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

Performs copy-assignment from source.

impl<I, U> Debug for Flatten<I> where
    I: Debug + Iterator<Item: IntoIterator<IntoIter = U, Item = U::Item>>,
    U: Debug + Iterator, 

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

Formats the value using the given formatter.

impl<I, U> DoubleEndedIterator for Flatten<I> where
    I: DoubleEndedIterator<Item: IntoIterator<IntoIter = U, Item = U::Item>>,
    U: DoubleEndedIterator, 

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

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

pub fn try_rfold<Acc, Fold, R>(&mut self, init: Acc, fold: Fold) -> R where
    Self: Sized,
    Fold: FnMut(Acc, Self::Item) -> R,
    R: Try<Ok = Acc>, 

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

pub fn rfold<Acc, Fold>(self, init: Acc, fold: Fold) -> Acc where
    Fold: FnMut(Acc, Self::Item) -> Acc, 

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

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

🔬 This is a nightly-only experimental API. (iter_advance_by #77404)

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

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

impl<I, U> FusedIterator for Flatten<I> where
    I: FusedIterator<Item: IntoIterator<IntoIter = U, Item = U::Item>>,
    U: Iterator, 

impl<I, U> Iterator for Flatten<I> where
    I: Iterator<Item: IntoIterator<IntoIter = U, Item = U::Item>>,
    U: Iterator, 

type Item = U::Item

The type of the elements being iterated over.

pub fn next(&mut self) -> Option<U::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 try_fold<Acc, Fold, R>(&mut self, init: Acc, fold: Fold) -> R where
    Self: Sized,
    Fold: FnMut(Acc, Self::Item) -> R,
    R: Try<Ok = Acc>, 

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

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

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

pub fn count(self) -> usize where
    Self: Sized, 

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

pub fn last(self) -> Option<Self::Item> where
    Self: Sized, 

Consumes the iterator, returning the last element.

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

🔬 This is a nightly-only experimental API. (iter_advance_by #77404)

recently added

Advances the iterator by n elements.

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

Returns the nth element of the iterator.

pub fn step_by(self, step: usize) -> StepBy<Self> where
    Self: Sized, 

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::IntoIter> where
    Self: Sized,
    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::IntoIter> where
    Self: Sized,
    U: IntoIterator, 

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

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

Calls a closure on each element of an iterator.

pub fn filter<P>(self, predicate: P) -> Filter<Self, P> where
    Self: Sized,
    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
    Self: Sized,
    F: FnMut(Self::Item) -> Option<B>, 

Creates an iterator that both filters and maps.

pub fn enumerate(self) -> Enumerate<Self> where
    Self: Sized, 

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

pub fn peekable(self) -> Peekable<Self> where
    Self: Sized, 

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
    Self: Sized,
    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
    Self: Sized,
    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
    Self: Sized,
    P: FnMut(Self::Item) -> Option<B>, 

🔬 This is a nightly-only experimental API. (iter_map_while #68537)

recently added

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

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

Creates an iterator that skips the first n elements.

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

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
    Self: Sized,
    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
    Self: Sized,
    U: IntoIterator,
    F: FnMut(Self::Item) -> U, 

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

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

Creates an iterator that flattens nested structure.

pub fn fuse(self) -> Fuse<Self> where
    Self: Sized, 

Creates an iterator which ends after the first None.

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

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

pub fn by_ref(&mut self) -> &mut Self where
    Self: Sized, 

Borrows an iterator, rather than consuming it.

#[must_use = "if you really need to exhaust the iterator, consider `.for_each(drop)` instead"]pub fn collect<B: FromIterator<Self::Item>>(self) -> B where
    Self: Sized, 

Transforms an iterator into a collection.

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

Consumes an iterator, creating two collections from it.

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

🔬 This is a nightly-only experimental API. (iter_partition_in_place #62543)

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
    Self: Sized,
    P: FnMut(Self::Item) -> bool, 

🔬 This is a nightly-only experimental API. (iter_is_partitioned #62544)

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_for_each<F, R>(&mut self, f: F) -> R where
    Self: Sized,
    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 fold_first<F>(self, f: F) -> Option<Self::Item> where
    Self: Sized,
    F: FnMut(Self::Item, Self::Item) -> Self::Item, 

🔬 This is a nightly-only experimental API. (iterator_fold_self #68125)

The same as fold(), but uses the first element in the iterator as the initial value, folding every subsequent element into it. If the iterator is empty, return None; otherwise, return the result of the fold.

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

Tests if every element of the iterator matches a predicate.

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

🔬 This is a nightly-only experimental API. (try_find #63178)

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
    Self: Sized,
    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
    P: FnMut(Self::Item) -> bool,
    Self: Sized + ExactSizeIterator + DoubleEndedIterator, 

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

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

Returns the maximum element of an iterator.

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

Returns the minimum element of an iterator.

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

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

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

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

pub fn min_by<F>(self, compare: F) -> Option<Self::Item> where
    Self: Sized,
    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: Sized + DoubleEndedIterator, 

Reverses an iterator's direction.

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

Converts an iterator of pairs into a pair of containers.

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

Creates an iterator which copies all of its elements.

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

Creates an iterator which clones all of its elements.

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

Repeats an iterator endlessly.

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

Sums the elements of an iterator.

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

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

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

🔬 This is a nightly-only experimental API. (iter_order_by #64295)

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::Item>,
    Self: Sized, 

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
    Self: Sized,
    I: IntoIterator,
    F: FnMut(Self::Item, I::Item) -> Option<Ordering>, 

🔬 This is a nightly-only experimental API. (iter_order_by #64295)

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::Item>,
    Self: Sized, 

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
    Self: Sized,
    I: IntoIterator,
    F: FnMut(Self::Item, I::Item) -> bool, 

🔬 This is a nightly-only experimental API. (iter_order_by #64295)

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::Item>,
    Self: Sized, 

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::Item>,
    Self: Sized, 

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::Item>,
    Self: Sized, 

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::Item>,
    Self: Sized, 

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::Item>,
    Self: Sized, 

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: Sized,
    Self::Item: PartialOrd, 

🔬 This is a nightly-only experimental API. (is_sorted #53485)

new API

Checks if the elements of this iterator are sorted.

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

🔬 This is a nightly-only experimental API. (is_sorted #53485)

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
    Self: Sized,
    F: FnMut(Self::Item) -> K,
    K: PartialOrd, 

🔬 This is a nightly-only experimental API. (is_sorted #53485)

new API

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