Struct core::iter::MapWhile

pub struct MapWhile<I, P> { /* private fields */ }

An iterator that only accepts elements while predicate returns Some(_).

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

Trait Implementations

impl<I: Clone, P: Clone> Clone for MapWhile<I, P>

fn clone(&self) -> MapWhile<I, P>

Returns a copy of the value.

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

Performs copy-assignment from source.

impl<I: Debug, P> Debug for MapWhile<I, P>

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

Formats the value using the given formatter.

impl<B, I: Iterator, P> Iterator for MapWhile<I, P> where
    P: FnMut(I::Item) -> Option<B>, 

type Item = B

The type of the elements being iterated over.

fn next(&mut self) -> Option<B>

Advances the iterator and returns the next value.

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

Returns the bounds on the remaining length of the iterator.

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

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

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

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

fn next_chunk<const N: usize>(
    &mut self
) -> Result<[Self::Item; N], IntoIter<Self::Item, N>> where
    Self: Sized, 

🔬 This is a nightly-only experimental API. (iter_next_chunk #98326)

Advances the iterator and returns an array containing the next N values.

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

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

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

Consumes the iterator, returning the last element.

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

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

Advances the iterator by n elements.

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

Returns the nth element of the iterator.

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.

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.

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.

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

🔬 This is a nightly-only experimental API. (iter_intersperse #79524)

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

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.

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

Calls a closure on each element of an iterator.

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.

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.

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

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

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

Creates an iterator which can use the peek and peek_mut methods to look at the next element of the iterator without consuming it. See their documentation for more information.

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.

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.

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

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

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

Creates an iterator that skips the first n elements.

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

Creates an iterator that yields the first n elements, or fewer if the underlying iterator ends sooner.

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 adapter similar to fold that holds internal state and produces a new iterator.

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.

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

Creates an iterator which ends after the first None.

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.

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

Borrows an iterator, rather than consuming it.

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

Transforms an iterator into a collection.

fn collect_into<E: Extend<Self::Item>>(self, collection: &mut E) -> &mut E where
    Self: Sized, 

🔬 This is a nightly-only experimental API. (iter_collect_into #94780)

Collects all the items from an iterator into a collection.

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.

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)

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.

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

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

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

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

fn try_reduce<F, R>(
    &mut self,
    f: F
) -> <<R as Try>::Residual as Residual<Option<R::Output>>>::TryType where
    Self: Sized,
    F: FnMut(Self::Item, Self::Item) -> R,
    R: Try<Output = Self::Item>,
    R::Residual: Residual<Option<Self::Item>>, 

🔬 This is a nightly-only experimental API. (iterator_try_reduce #87053)

Reduces the elements to a single one by repeatedly applying a reducing operation. If the closure returns a failure, the failure is propagated back to the caller immediately.

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.

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.

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.

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.

fn try_find<F, R>(
    &mut self,
    f: F
) -> <<R as Try>::Residual as Residual<Option<Self::Item>>>::TryType where
    Self: Sized,
    F: FnMut(&Self::Item) -> R,
    R: Try<Output = bool>,
    R::Residual: Residual<Option<Self::Item>>, 

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

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

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.

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.

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.

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.

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.

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.

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.

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.

fn array_chunks<const N: usize>(self) -> ArrayChunks<Self, N> where
    Self: Sized, 

🔬 This is a nightly-only experimental API. (iter_array_chunks #100450)

Returns an iterator over N elements of the iterator at a time.

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

Sums the elements of an iterator.

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

Iterates over the entire iterator, multiplying all the elements

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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)

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

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)

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