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.
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:
fn main() { let numbers = vec![1, 2, 3]; let mut iter = numbers.iter(); assert_eq!(Some(&1), iter.next()); assert_eq!(Some(&3), iter.next_back()); assert_eq!(Some(&2), iter.next_back()); assert_eq!(None, iter.next()); assert_eq!(None, iter.next_back()); }let numbers = vec![1, 2, 3]; let mut iter = numbers.iter(); assert_eq!(Some(&1), iter.next()); assert_eq!(Some(&3), iter.next_back()); assert_eq!(Some(&2), iter.next_back()); assert_eq!(None, iter.next()); assert_eq!(None, iter.next_back());
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(); assert_eq!(Some(&1), iter.next()); assert_eq!(Some(&3), iter.next_back()); assert_eq!(Some(&2), iter.next_back()); assert_eq!(None, iter.next()); assert_eq!(None, iter.next_back()); }let numbers = vec![1, 2, 3]; let mut iter = numbers.iter(); assert_eq!(Some(&1), iter.next()); assert_eq!(Some(&3), iter.next_back()); assert_eq!(Some(&2), iter.next_back()); assert_eq!(None, iter.next()); assert_eq!(None, iter.next_back());
Implementors
impl<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 B: DoubleEndedIterator<Item=A::Item>, A: DoubleEndedIteratorimpl<A, B> DoubleEndedIterator for Zip<A, B> where A: DoubleEndedIterator + ExactSizeIterator, B: DoubleEndedIterator + ExactSizeIteratorimpl<B, I, F> DoubleEndedIterator for Map<I, F> where I: DoubleEndedIterator, F: FnMut(I::Item) -> Bimpl<I, P> DoubleEndedIterator for Filter<I, P> where I: DoubleEndedIterator, P: FnMut(&I::Item) -> boolimpl<B, I, F> DoubleEndedIterator for FilterMap<I, F> where I: DoubleEndedIterator, F: FnMut(I::Item) -> Option<B>impl<I> DoubleEndedIterator for Enumerate<I> where I: ExactSizeIterator + DoubleEndedIteratorimpl<I> DoubleEndedIterator for Skip<I> where I: DoubleEndedIterator + ExactSizeIteratorimpl<I, U, F> DoubleEndedIterator for FlatMap<I, U, F> where F: FnMut(I::Item) -> U, U: IntoIterator, I: DoubleEndedIterator, U::IntoIter: DoubleEndedIteratorimpl<I> DoubleEndedIterator for Fuse<I> where I: DoubleEndedIteratorimpl<I, F> DoubleEndedIterator for Inspect<I, F> where F: FnMut(&I::Item) -> (), I: DoubleEndedIteratorimpl<A> DoubleEndedIterator for Repeat<A> where A: Cloneimpl<T> DoubleEndedIterator for Empty<T>impl<T> DoubleEndedIterator for Once<T>impl<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 RangeInclusive<A> where A: Step + One, &'a A: Add<&'a A>, &'a A: Sub<&'a A>, &'a A::Output == A, &'a A::Output == Aimpl<'a, T> DoubleEndedIterator for Iter<'a, T>impl<'a, T> DoubleEndedIterator for IterMut<'a, T>impl<T> DoubleEndedIterator for IntoIter<T>impl<'a, A> DoubleEndedIterator for Iter<'a, A>impl<'a, A> DoubleEndedIterator for IterMut<'a, A>impl<A> DoubleEndedIterator for IntoIter<A>impl<I> DoubleEndedIterator for Box<I> where I: DoubleEndedIterator + ?Sizedimpl<'a, T, P> DoubleEndedIterator for Split<'a, T, P> where P: FnMut(&T) -> boolimpl<'a, T> DoubleEndedIterator for Iter<'a, T>impl<'a, T> DoubleEndedIterator for Chunks<'a, T>impl<'a, T> DoubleEndedIterator for IterMut<'a, T>impl<'a, T> DoubleEndedIterator for Windows<'a, T>impl<'a, T, P> DoubleEndedIterator for SplitMut<'a, T, P> where P: FnMut(&T) -> boolimpl<'a, T> DoubleEndedIterator for ChunksMut<'a, T>impl<'a, P> DoubleEndedIterator for MatchIndices<'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> DoubleEndedIterator for SplitWhitespace<'a>impl<'a> DoubleEndedIterator for CharIndices<'a>impl<'a, P> DoubleEndedIterator for Split<'a, P> where P: Pattern<'a>, P::Searcher: DoubleEndedSearcher<'a>impl<'a> DoubleEndedIterator for LinesAny<'a>impl<'a> DoubleEndedIterator for Lines<'a>impl<'a> DoubleEndedIterator for Chars<'a>impl<'a, P> DoubleEndedIterator for RMatches<'a, P> where P: Pattern<'a>, P::Searcher: DoubleEndedSearcher<'a>impl<'a> DoubleEndedIterator for Bytes<'a>impl<'a, P> DoubleEndedIterator for Matches<'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 RMatchIndices<'a, P> where P: Pattern<'a>, P::Searcher: DoubleEndedSearcher<'a>impl<'a> DoubleEndedIterator for Drain<'a>impl<T> DoubleEndedIterator for IntoIter<T>impl<'a, T> DoubleEndedIterator for Drain<'a, T>impl DoubleEndedIterator for EscapeDefaultimpl<'a, T> DoubleEndedIterator for Iter<'a, T>impl<T> DoubleEndedIterator for IntoIter<T>impl<'a, T> DoubleEndedIterator for Drain<'a, T> where T: 'aimpl<'a, K, V> DoubleEndedIterator for ValuesMut<'a, K, V>impl<'a, K, V> DoubleEndedIterator for Values<'a, K, V>impl<'a, K, V> DoubleEndedIterator for Iter<'a, K, V> where V: 'a, K: 'aimpl<'a, K, V> DoubleEndedIterator for RangeMut<'a, K, V>impl<'a, K, V> DoubleEndedIterator for Keys<'a, K, V>impl<'a, K, V> DoubleEndedIterator for IterMut<'a, K, V> where V: 'a, K: 'aimpl<'a, K, V> DoubleEndedIterator for Range<'a, K, V>impl<K, V> DoubleEndedIterator for IntoIter<K, V>impl<'a, T> DoubleEndedIterator for Range<'a, T>impl<'a, T> DoubleEndedIterator for Iter<'a, T>impl<T> DoubleEndedIterator for IntoIter<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, 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 Iter<'a>impl<'a> DoubleEndedIterator for Components<'a>