Trait core::iter::DoubleEndedIterator 1.0.0
[−]
[src]
pub trait DoubleEndedIterator: Iterator { fn next_back(&mut self) -> Option<Self::Item>; }
An iterator able to yield elements from both ends.
Something that implements DoubleEndedIterator
has one extra capability
over something that implements Iterator
: the ability to also take
Item
s from the back, as well as the front.
It is important to note that both back and forth work on the same range, and do not cross: iteration is over when they meet in the middle.
In a similar fashion to the Iterator
protocol, once a
DoubleEndedIterator
returns None
from a next_back()
, calling it again
may or may not ever return Some
again. next()
and next_back()
are
interchangable for this purpose.
Examples
Basic usage:
let numbers = vec![1, 2, 3, 4, 5, 6]; let mut iter = numbers.iter(); assert_eq!(Some(&1), iter.next()); assert_eq!(Some(&6), iter.next_back()); assert_eq!(Some(&5), iter.next_back()); assert_eq!(Some(&2), iter.next()); assert_eq!(Some(&3), iter.next()); assert_eq!(Some(&4), iter.next()); assert_eq!(None, iter.next()); assert_eq!(None, iter.next_back());Run
Required Methods
fn next_back(&mut self) -> Option<Self::Item>
Removes and returns an element from the end of the iterator.
Returns None
when there are no more elements.
The trait-level docs contain more details.
Examples
Basic usage:
let numbers = vec![1, 2, 3, 4, 5, 6]; let mut iter = numbers.iter(); assert_eq!(Some(&1), iter.next()); assert_eq!(Some(&6), iter.next_back()); assert_eq!(Some(&5), iter.next_back()); assert_eq!(Some(&2), iter.next()); assert_eq!(Some(&3), iter.next()); assert_eq!(Some(&4), iter.next()); assert_eq!(None, iter.next()); assert_eq!(None, iter.next_back());Run
Implementors
impl<A: Step + Clone> DoubleEndedIterator for Range<A> where &'a A: Add<&'a A, Output=A>,
&'a A: Sub<&'a A, Output=A>impl<A: Step> DoubleEndedIterator for RangeInclusive<A> where &'a A: Add<&'a A, Output=A>,
&'a A: Sub<&'a A, Output=A>impl<A: Clone> DoubleEndedIterator for Repeat<A>
impl<T> DoubleEndedIterator for Empty<T>
impl<T> DoubleEndedIterator for Once<T>
impl<'a, I: DoubleEndedIterator + ?Sized> DoubleEndedIterator for &'a mut I
impl<I> DoubleEndedIterator for Rev<I> where I: DoubleEndedIterator
impl<'a, I, T: 'a> DoubleEndedIterator for Cloned<I> where I: DoubleEndedIterator<Item=&'a T>,
T: Cloneimpl<A, B> DoubleEndedIterator for Chain<A, B> where A: DoubleEndedIterator,
B: DoubleEndedIterator<Item=A::Item>impl<A, B> DoubleEndedIterator for Zip<A, B> where A: DoubleEndedIterator + ExactSizeIterator,
B: DoubleEndedIterator + ExactSizeIteratorimpl<B, I: DoubleEndedIterator, F> DoubleEndedIterator for Map<I, F> where F: FnMut(I::Item) -> B
impl<I: DoubleEndedIterator, P> DoubleEndedIterator for Filter<I, P> where P: FnMut(&I::Item) -> bool
impl<B, I: DoubleEndedIterator, F> DoubleEndedIterator for FilterMap<I, F> where F: FnMut(I::Item) -> Option<B>
impl<I> DoubleEndedIterator for Enumerate<I> where I: ExactSizeIterator + DoubleEndedIterator
impl<I> DoubleEndedIterator for Skip<I> where I: DoubleEndedIterator + ExactSizeIterator
impl<I: DoubleEndedIterator, U, F> DoubleEndedIterator for FlatMap<I, U, F> where F: FnMut(I::Item) -> U,
U: IntoIterator,
U::IntoIter: DoubleEndedIteratorimpl<I> DoubleEndedIterator for core::iter::Fuse<I> where I: DoubleEndedIterator
impl<I> DoubleEndedIterator for core::iter::Fuse<I> where I: DoubleEndedIterator + FusedIterator
impl<I: DoubleEndedIterator, F> DoubleEndedIterator for Inspect<I, F> where F: FnMut(&I::Item)
impl<'a, A> DoubleEndedIterator for core::option::Iter<'a, A>
impl<'a, A> DoubleEndedIterator for core::option::IterMut<'a, A>
impl<A> DoubleEndedIterator for core::option::IntoIter<A>
impl<'a, T> DoubleEndedIterator for core::result::Iter<'a, T>
impl<'a, T> DoubleEndedIterator for core::result::IterMut<'a, T>
impl<T> DoubleEndedIterator for core::result::IntoIter<T>
impl<'a, T> DoubleEndedIterator for core::slice::Iter<'a, T>
impl<'a, T> DoubleEndedIterator for core::slice::IterMut<'a, T>
impl<'a, T, P> DoubleEndedIterator for core::slice::Split<'a, T, P> where P: FnMut(&T) -> bool
impl<'a, T, P> DoubleEndedIterator for SplitMut<'a, T, P> where P: FnMut(&T) -> bool
impl<'a, T> DoubleEndedIterator for Windows<'a, T>
impl<'a, T> DoubleEndedIterator for Chunks<'a, T>
impl<'a, T> DoubleEndedIterator for ChunksMut<'a, T>
impl<'a> DoubleEndedIterator for Chars<'a>
impl<'a> DoubleEndedIterator for CharIndices<'a>
impl<'a> DoubleEndedIterator for Bytes<'a>
impl<'a, P: Pattern<'a>> DoubleEndedIterator for core::str::Split<'a, P> where P::Searcher: DoubleEndedSearcher<'a>
impl<'a, P: Pattern<'a>> DoubleEndedIterator for RSplit<'a, P> where P::Searcher: DoubleEndedSearcher<'a>
impl<'a, P: Pattern<'a>> DoubleEndedIterator for SplitTerminator<'a, P> where P::Searcher: DoubleEndedSearcher<'a>
impl<'a, P: Pattern<'a>> DoubleEndedIterator for RSplitTerminator<'a, P> where P::Searcher: DoubleEndedSearcher<'a>
impl<'a, P: Pattern<'a>> DoubleEndedIterator for MatchIndices<'a, P> where P::Searcher: DoubleEndedSearcher<'a>
impl<'a, P: Pattern<'a>> DoubleEndedIterator for RMatchIndices<'a, P> where P::Searcher: DoubleEndedSearcher<'a>
impl<'a, P: Pattern<'a>> DoubleEndedIterator for Matches<'a, P> where P::Searcher: DoubleEndedSearcher<'a>
impl<'a, P: Pattern<'a>> DoubleEndedIterator for RMatches<'a, P> where P::Searcher: DoubleEndedSearcher<'a>
impl<'a> DoubleEndedIterator for Lines<'a>
impl<'a> DoubleEndedIterator for LinesAny<'a>