Trait std::iter::DoubleEndedIterator
[−]
[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
Items 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.
Examples
Basic usage:
fn main() { let numbers = vec![1, 2, 3]; let mut iter = numbers.iter(); let n = iter.next(); assert_eq!(Some(&1), n); let n = iter.next_back(); assert_eq!(Some(&3), n); let n = iter.next_back(); assert_eq!(Some(&2), n); let n = iter.next(); assert_eq!(None, n); let n = iter.next_back(); assert_eq!(None, n); }let numbers = vec![1, 2, 3]; let mut iter = numbers.iter(); let n = iter.next(); assert_eq!(Some(&1), n); let n = iter.next_back(); assert_eq!(Some(&3), n); let n = iter.next_back(); assert_eq!(Some(&2), n); let n = iter.next(); assert_eq!(None, n); let n = iter.next_back(); assert_eq!(None, n);
Required Methods
fn next_back(&mut self) -> Option<Self::Item>
An iterator able to yield elements from both ends.
As this is the only method for this trait, the trait-level docs contain more details.
Examples
Basic usage:
fn main() { let numbers = vec![1, 2, 3]; let mut iter = numbers.iter(); let n = iter.next(); assert_eq!(Some(&1), n); let n = iter.next_back(); assert_eq!(Some(&3), n); let n = iter.next_back(); assert_eq!(Some(&2), n); let n = iter.next(); assert_eq!(None, n); let n = iter.next_back(); assert_eq!(None, n); }let numbers = vec![1, 2, 3]; let mut iter = numbers.iter(); let n = iter.next(); assert_eq!(Some(&1), n); let n = iter.next_back(); assert_eq!(Some(&3), n); let n = iter.next_back(); assert_eq!(Some(&2), n); let n = iter.next(); assert_eq!(None, n); let n = iter.next_back(); assert_eq!(None, n);
Implementors
impl<'a, I> DoubleEndedIterator for &'a mut I where I: DoubleEndedIterator + ?Sizedimpl<I> DoubleEndedIterator for Rev<I> where I: DoubleEndedIteratorimpl<'a, I, T> DoubleEndedIterator for Cloned<I> where I: DoubleEndedIterator<Item=&'a T>, T: 'a + 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, F> DoubleEndedIterator for Map<I, F> where F: FnMut(I::Item) -> B, I: DoubleEndedIteratorimpl<I, P> DoubleEndedIterator for Filter<I, P> where I: DoubleEndedIterator, P: FnMut(&I::Item) -> boolimpl<B, I, F> DoubleEndedIterator for FilterMap<I, F> where F: FnMut(I::Item) -> Option<B>, I: DoubleEndedIteratorimpl<I> DoubleEndedIterator for Enumerate<I> where I: ExactSizeIterator + DoubleEndedIteratorimpl<I, U, F> DoubleEndedIterator for FlatMap<I, U, F> where F: FnMut(I::Item) -> U, I: DoubleEndedIterator, U: IntoIterator, U::IntoIter: DoubleEndedIteratorimpl<I> DoubleEndedIterator for Fuse<I> where I: DoubleEndedIteratorimpl<I, F> DoubleEndedIterator for Inspect<I, F> where I: DoubleEndedIterator, F: FnMut(&I::Item) -> ()impl<A> DoubleEndedIterator for RangeInclusive<A> where A: Step + One + Clone + PartialEq<A>, &'a A: Add<&'a A>, &'a A: Sub<&'a A>, &'a A::Output == A, &'a A::Output == Aimpl<A> DoubleEndedIterator for Range<A> where A: Clone + Step + One, &'a A: Add<&'a A>, &'a A: Sub<&'a A>, &'a A::Output == A, &'a A::Output == Aimpl<A> DoubleEndedIterator for Repeat<A> where A: Cloneimpl<T> DoubleEndedIterator for Empty<T>impl<T> DoubleEndedIterator for Once<T>impl<A> DoubleEndedIterator for Item<A>impl<'a, A> DoubleEndedIterator for Iter<'a, A>impl<'a, A> DoubleEndedIterator for IterMut<'a, A>impl<A> DoubleEndedIterator for IntoIter<A>impl<'a, T> DoubleEndedIterator for Iter<'a, T>impl<'a, T> DoubleEndedIterator for IterMut<'a, T>impl<T> DoubleEndedIterator for IntoIter<T>impl<'a, T> DoubleEndedIterator for Iter<'a, T>impl<'a, T> DoubleEndedIterator for IterMut<'a, T>impl<'a, T, P> DoubleEndedIterator for Split<'a, T, P> where P: FnMut(&T) -> boolimpl<'a, T, P> DoubleEndedIterator for SplitMut<'a, T, P> where P: FnMut(&T) -> boolimpl<'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> DoubleEndedIterator for Split<'a, P> where P: Pattern<'a>, P::Searcher: DoubleEndedSearcher<'a>impl<'a, P> DoubleEndedIterator for RSplit<'a, P> where P: Pattern<'a>, P::Searcher: DoubleEndedSearcher<'a>impl<'a, P> DoubleEndedIterator for SplitTerminator<'a, P> where P: Pattern<'a>, P::Searcher: DoubleEndedSearcher<'a>impl<'a, P> DoubleEndedIterator for RSplitTerminator<'a, P> where P: Pattern<'a>, P::Searcher: DoubleEndedSearcher<'a>impl<'a, P> DoubleEndedIterator for MatchIndices<'a, P> where P: Pattern<'a>, P::Searcher: DoubleEndedSearcher<'a>impl<'a, P> DoubleEndedIterator for RMatchIndices<'a, P> where P: Pattern<'a>, P::Searcher: DoubleEndedSearcher<'a>impl<'a, P> DoubleEndedIterator for Matches<'a, P> where P: Pattern<'a>, P::Searcher: DoubleEndedSearcher<'a>impl<'a, P> DoubleEndedIterator for RMatches<'a, P> where P: Pattern<'a>, P::Searcher: DoubleEndedSearcher<'a>impl<'a> DoubleEndedIterator for Lines<'a>impl<'a> DoubleEndedIterator for LinesAny<'a>impl<I> DoubleEndedIterator for Box<I> where I: DoubleEndedIterator + ?Sizedimpl<'a, T> DoubleEndedIterator for Iter<'a, T>impl<T> DoubleEndedIterator for IntoIter<T>impl<'a, T> DoubleEndedIterator for Drain<'a, T> where T: 'aimpl<T> DoubleEndedIterator for RawItems<T>impl<K, V, E, Impl> DoubleEndedIterator for AbsTraversal<Impl> where Impl: TraversalImpl<Item=(K, V), Edge=E>impl<K, V, E, T> DoubleEndedIterator for AbsIter<T> where T: DoubleEndedIterator<Item=TraversalItem<K, V, E>> + Traverse<E>impl<'a, K, V> DoubleEndedIterator for Iter<'a, K, V>impl<'a, K, V> DoubleEndedIterator for IterMut<'a, K, V>impl<K, V> DoubleEndedIterator for IntoIter<K, V>impl<'a, K, V> DoubleEndedIterator for Keys<'a, K, V>impl<'a, K, V> DoubleEndedIterator for Values<'a, K, V>impl<'a, K, V> DoubleEndedIterator for Range<'a, K, V>impl<'a, K, V> DoubleEndedIterator for RangeMut<'a, K, V>impl<'a, T> DoubleEndedIterator for Iter<'a, T>impl<T> DoubleEndedIterator for IntoIter<T>impl<'a, T> DoubleEndedIterator for Range<'a, T>impl<'a, A> DoubleEndedIterator for Iter<'a, A>impl<'a, A> DoubleEndedIterator for IterMut<'a, A>impl<A> DoubleEndedIterator for IntoIter<A>impl<'a> DoubleEndedIterator for Drain<'a>impl<T> DoubleEndedIterator for IntoIter<T>impl<'a, T> DoubleEndedIterator for Drain<'a, T>impl<'a, T> DoubleEndedIterator for Iter<'a, T>impl<'a, T> DoubleEndedIterator for IterMut<'a, T>impl<T> DoubleEndedIterator for IntoIter<T>impl<'a, T> DoubleEndedIterator for Drain<'a, T> where T: 'aimpl<'a> DoubleEndedIterator for SplitWhitespace<'a>impl DoubleEndedIterator for EscapeDefaultimpl<'a> DoubleEndedIterator for Iter<'a>impl<'a> DoubleEndedIterator for Components<'a>