1.0.0[][src]Trait tract_nnef::internal::tract_downcast_rs::__std::iter::ExactSizeIterator

pub trait ExactSizeIterator: Iterator {
    fn len(&self) -> usize { ... }
fn is_empty(&self) -> bool { ... } }

An iterator that knows its exact length.

Many Iterators don't know how many times they will iterate, but some do. If an iterator knows how many times it can iterate, providing access to that information can be useful. For example, if you want to iterate backwards, a good start is to know where the end is.

When implementing an ExactSizeIterator, you must also implement Iterator. When doing so, the implementation of size_hint must return the exact size of the iterator.

The len method has a default implementation, so you usually shouldn't implement it. However, you may be able to provide a more performant implementation than the default, so overriding it in this case makes sense.

Examples

Basic usage:

// a finite range knows exactly how many times it will iterate
let five = 0..5;

assert_eq!(5, five.len());

In the module level docs, we implemented an Iterator, Counter. Let's implement ExactSizeIterator for it as well:

impl ExactSizeIterator for Counter {
    // We can easily calculate the remaining number of iterations.
    fn len(&self) -> usize {
        5 - self.count
    }
}

// And now we can use it!

let counter = Counter::new();

assert_eq!(5, counter.len());

Provided methods

fn len(&self) -> usize

Returns the exact length of the iterator.

The implementation ensures that the iterator will return exactly len() more times a Some(T) value, before returning None. This method has a default implementation, so you usually should not implement it directly. However, if you can provide a more efficient implementation, you can do so. See the trait-level docs for an example.

This function has the same safety guarantees as the size_hint function.

Examples

Basic usage:

// a finite range knows exactly how many times it will iterate
let five = 0..5;

assert_eq!(5, five.len());

fn is_empty(&self) -> bool

🔬 This is a nightly-only experimental API. (exact_size_is_empty)

Returns true if the iterator is empty.

This method has a default implementation using self.len(), so you don't need to implement it yourself.

Examples

Basic usage:

#![feature(exact_size_is_empty)]

let mut one_element = std::iter::once(0);
assert!(!one_element.is_empty());

assert_eq!(one_element.next(), Some(0));
assert!(one_element.is_empty());

assert_eq!(one_element.next(), None);
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Implementations on Foreign Types

impl<'_, I> ExactSizeIterator for &'_ mut I where
    I: ExactSizeIterator + ?Sized
[src]

impl<'_, K, V> ExactSizeIterator for Values<'_, K, V>

impl<'_, K, V> ExactSizeIterator for Drain<'_, K, V>

impl<'_, K, V> ExactSizeIterator for Keys<'_, K, V>

impl<'_, K, V> ExactSizeIterator for Iter<'_, K, V>

impl<K, V> ExactSizeIterator for IntoIter<K, V>

impl<'_, K, V> ExactSizeIterator for ValuesMut<'_, K, V>

impl<'a, K> ExactSizeIterator for Iter<'a, K>

impl<K> ExactSizeIterator for IntoIter<K>

impl<'_, K> ExactSizeIterator for Drain<'_, K>

impl<'_, K, V> ExactSizeIterator for IterMut<'_, K, V>

impl<'a, B> ExactSizeIterator for Blocks<'a, B> where
    B: BitBlock, 

impl<'a, B> ExactSizeIterator for Iter<'a, B> where
    B: BitBlock, 

impl<B> ExactSizeIterator for IntoIter<B> where
    B: BitBlock, 

impl<I, J> ExactSizeIterator for ZipEq<I, J> where
    I: ExactSizeIterator,
    J: ExactSizeIterator
[src]

impl<A, B> ExactSizeIterator for Zip<(A, B)> where
    A: ExactSizeIterator,
    B: ExactSizeIterator
[src]

impl<I> ExactSizeIterator for ExactlyOneError<I> where
    I: ExactSizeIterator
[src]

impl<A, B, C, D, E> ExactSizeIterator for Zip<(A, B, C, D, E)> where
    A: ExactSizeIterator,
    B: ExactSizeIterator,
    C: ExactSizeIterator,
    D: ExactSizeIterator,
    E: ExactSizeIterator
[src]

impl<T> ExactSizeIterator for TupleBuffer<T> where
    T: TupleCollect, 
[src]

impl<A, B, C, D> ExactSizeIterator for Zip<(A, B, C, D)> where
    A: ExactSizeIterator,
    B: ExactSizeIterator,
    C: ExactSizeIterator,
    D: ExactSizeIterator
[src]

impl<A, B, C> ExactSizeIterator for Zip<(A, B, C)> where
    A: ExactSizeIterator,
    B: ExactSizeIterator,
    C: ExactSizeIterator
[src]

impl<A, B, C, D, E, F, G, H> ExactSizeIterator for Zip<(A, B, C, D, E, F, G, H)> where
    A: ExactSizeIterator,
    B: ExactSizeIterator,
    C: ExactSizeIterator,
    D: ExactSizeIterator,
    E: ExactSizeIterator,
    F: ExactSizeIterator,
    G: ExactSizeIterator,
    H: ExactSizeIterator
[src]

impl<A, B, C, D, E, F> ExactSizeIterator for Zip<(A, B, C, D, E, F)> where
    A: ExactSizeIterator,
    B: ExactSizeIterator,
    C: ExactSizeIterator,
    D: ExactSizeIterator,
    E: ExactSizeIterator,
    F: ExactSizeIterator
[src]

impl<I, F> ExactSizeIterator for Update<I, F> where
    F: FnMut(&mut <I as Iterator>::Item),
    I: ExactSizeIterator
[src]

impl<A, B, C, D, E, F, G> ExactSizeIterator for Zip<(A, B, C, D, E, F, G)> where
    A: ExactSizeIterator,
    B: ExactSizeIterator,
    C: ExactSizeIterator,
    D: ExactSizeIterator,
    E: ExactSizeIterator,
    F: ExactSizeIterator,
    G: ExactSizeIterator
[src]

impl<I, R> ExactSizeIterator for MapInto<I, R> where
    I: ExactSizeIterator,
    <I as Iterator>::Item: Into<R>, 
[src]

impl<T, U> ExactSizeIterator for ZipLongest<T, U> where
    T: ExactSizeIterator,
    U: ExactSizeIterator
[src]

impl<I> ExactSizeIterator for Step<I> where
    I: ExactSizeIterator
[src]

impl<A> ExactSizeIterator for Zip<(A,)> where
    A: ExactSizeIterator
[src]

impl<I, F> ExactSizeIterator for PadUsing<I, F> where
    F: FnMut(usize) -> <I as Iterator>::Item,
    I: ExactSizeIterator
[src]

impl<I> ExactSizeIterator for WithPosition<I> where
    I: ExactSizeIterator
[src]

impl<A> ExactSizeIterator for RepeatN<A> where
    A: Clone
[src]

impl<A> ExactSizeIterator for IntoIter<A> where
    A: Array, 

impl<'a, T> ExactSizeIterator for Drain<'a, T> where
    T: Array, 

impl<'a, A> ExactSizeIterator for Drain<'a, A> where
    A: Array,
    <A as Array>::Item: 'a, 
[src]

impl<A> ExactSizeIterator for IntoIter<A> where
    A: Array
[src]

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Implementors

impl ExactSizeIterator for tract_nnef::internal::tract_downcast_rs::__std::ascii::EscapeDefault[src]

impl ExactSizeIterator for EscapeDebug[src]

impl ExactSizeIterator for tract_nnef::internal::tract_downcast_rs::__std::char::EscapeDefault[src]

impl ExactSizeIterator for EscapeUnicode[src]

impl ExactSizeIterator for ToLowercase[src]

impl ExactSizeIterator for ToUppercase[src]

impl ExactSizeIterator for Args[src]

impl ExactSizeIterator for ArgsOs[src]

impl ExactSizeIterator for Range<i8>[src]

impl ExactSizeIterator for Range<i16>[src]

impl ExactSizeIterator for Range<i32>[src]

impl ExactSizeIterator for Range<isize>[src]

impl ExactSizeIterator for Range<u8>[src]

impl ExactSizeIterator for Range<u16>[src]

impl ExactSizeIterator for Range<u32>[src]

impl ExactSizeIterator for Range<usize>[src]

impl ExactSizeIterator for RangeInclusive<i8>[src]

impl ExactSizeIterator for RangeInclusive<i16>[src]

impl ExactSizeIterator for RangeInclusive<u8>[src]

impl ExactSizeIterator for RangeInclusive<u16>[src]

impl<'_> ExactSizeIterator for Bytes<'_>[src]

impl<'_, A> ExactSizeIterator for tract_nnef::internal::tract_downcast_rs::__std::option::Iter<'_, A>[src]

impl<'_, A> ExactSizeIterator for tract_nnef::internal::tract_downcast_rs::__std::option::IterMut<'_, A>[src]

impl<'_, I> ExactSizeIterator for Splice<'_, I> where
    I: Iterator
[src]

impl<'_, K> ExactSizeIterator for tract_nnef::internal::tract_downcast_rs::__std::collections::hash_set::Drain<'_, K>[src]

impl<'_, K> ExactSizeIterator for tract_nnef::internal::tract_downcast_rs::__std::collections::hash_set::Iter<'_, K>[src]

impl<'_, K, V> ExactSizeIterator for tract_nnef::internal::tract_downcast_rs::__std::collections::btree_map::Iter<'_, K, V>[src]

impl<'_, K, V> ExactSizeIterator for tract_nnef::internal::tract_downcast_rs::__std::collections::btree_map::IterMut<'_, K, V>[src]

impl<'_, K, V> ExactSizeIterator for tract_nnef::internal::tract_downcast_rs::__std::collections::btree_map::Keys<'_, K, V>[src]

impl<'_, K, V> ExactSizeIterator for tract_nnef::internal::tract_downcast_rs::__std::collections::btree_map::Values<'_, K, V>[src]

impl<'_, K, V> ExactSizeIterator for tract_nnef::internal::tract_downcast_rs::__std::collections::btree_map::ValuesMut<'_, K, V>[src]

impl<'_, K, V> ExactSizeIterator for tract_nnef::internal::tract_downcast_rs::__std::collections::hash_map::Drain<'_, K, V>[src]

impl<'_, K, V> ExactSizeIterator for tract_nnef::internal::tract_downcast_rs::__std::collections::hash_map::Iter<'_, K, V>[src]

impl<'_, K, V> ExactSizeIterator for tract_nnef::internal::tract_downcast_rs::__std::collections::hash_map::IterMut<'_, K, V>[src]

impl<'_, K, V> ExactSizeIterator for tract_nnef::internal::tract_downcast_rs::__std::collections::hash_map::Keys<'_, K, V>[src]

impl<'_, K, V> ExactSizeIterator for tract_nnef::internal::tract_downcast_rs::__std::collections::hash_map::Values<'_, K, V>[src]

impl<'_, K, V> ExactSizeIterator for tract_nnef::internal::tract_downcast_rs::__std::collections::hash_map::ValuesMut<'_, K, V>[src]

impl<'_, T> ExactSizeIterator for tract_nnef::internal::tract_downcast_rs::__std::collections::binary_heap::Drain<'_, T>[src]

impl<'_, T> ExactSizeIterator for DrainSorted<'_, T> where
    T: Ord
[src]

impl<'_, T> ExactSizeIterator for tract_nnef::internal::tract_downcast_rs::__std::collections::binary_heap::Iter<'_, T>[src]

impl<'_, T> ExactSizeIterator for tract_nnef::internal::tract_downcast_rs::__std::collections::btree_set::Iter<'_, T>[src]

impl<'_, T> ExactSizeIterator for tract_nnef::internal::tract_downcast_rs::__std::collections::linked_list::Iter<'_, T>[src]

impl<'_, T> ExactSizeIterator for tract_nnef::internal::tract_downcast_rs::__std::collections::linked_list::IterMut<'_, T>[src]

impl<'_, T> ExactSizeIterator for tract_nnef::internal::tract_downcast_rs::__std::collections::vec_deque::Drain<'_, T>[src]

impl<'_, T> ExactSizeIterator for tract_nnef::internal::tract_downcast_rs::__std::collections::vec_deque::Iter<'_, T>[src]

impl<'_, T> ExactSizeIterator for tract_nnef::internal::tract_downcast_rs::__std::collections::vec_deque::IterMut<'_, T>[src]

impl<'_, T> ExactSizeIterator for tract_nnef::internal::tract_downcast_rs::__std::result::Iter<'_, T>[src]

impl<'_, T> ExactSizeIterator for tract_nnef::internal::tract_downcast_rs::__std::result::IterMut<'_, T>[src]

impl<'_, T> ExactSizeIterator for Chunks<'_, T>[src]

impl<'_, T> ExactSizeIterator for ChunksExact<'_, T>[src]

impl<'_, T> ExactSizeIterator for ChunksExactMut<'_, T>[src]

impl<'_, T> ExactSizeIterator for ChunksMut<'_, T>[src]

impl<'_, T> ExactSizeIterator for tract_nnef::internal::tract_downcast_rs::__std::slice::Iter<'_, T>[src]

impl<'_, T> ExactSizeIterator for tract_nnef::internal::tract_downcast_rs::__std::slice::IterMut<'_, T>[src]

impl<'_, T> ExactSizeIterator for RChunks<'_, T>[src]

impl<'_, T> ExactSizeIterator for RChunksExactMut<'_, T>[src]

impl<'_, T> ExactSizeIterator for RChunksMut<'_, T>[src]

impl<'_, T> ExactSizeIterator for Windows<'_, T>[src]

impl<'_, T> ExactSizeIterator for tract_nnef::internal::tract_downcast_rs::__std::vec::Drain<'_, T>[src]

impl<'_, T, const N: usize> ExactSizeIterator for ArrayChunks<'_, T, N>[src]

impl<'a, A, D> ExactSizeIterator for AxisChunksIter<'a, A, D> where
    D: Dimension
[src]

impl<'a, A, D> ExactSizeIterator for AxisChunksIterMut<'a, A, D> where
    D: Dimension
[src]

impl<'a, A, D> ExactSizeIterator for AxisIter<'a, A, D> where
    D: Dimension
[src]

impl<'a, A, D> ExactSizeIterator for AxisIterMut<'a, A, D> where
    D: Dimension
[src]

impl<'a, A, D> ExactSizeIterator for IndexedIter<'a, A, D> where
    D: Dimension
[src]

impl<'a, A, D> ExactSizeIterator for IndexedIterMut<'a, A, D> where
    D: Dimension
[src]

impl<'a, A, D> ExactSizeIterator for tract_nnef::internal::tract_ndarray::iter::Iter<'a, A, D> where
    D: Dimension
[src]

impl<'a, A, D> ExactSizeIterator for tract_nnef::internal::tract_ndarray::iter::IterMut<'a, A, D> where
    D: Dimension
[src]

impl<'a, A, D> ExactSizeIterator for LanesIter<'a, A, D> where
    D: Dimension
[src]

impl<'a, A, D> ExactSizeIterator for LanesIterMut<'a, A, D> where
    D: Dimension
[src]

impl<'a, I, T> ExactSizeIterator for Cloned<I> where
    I: ExactSizeIterator<Item = &'a T>,
    T: 'a + Clone
[src]

impl<'a, I, T> ExactSizeIterator for Copied<I> where
    I: ExactSizeIterator<Item = &'a T>,
    T: 'a + Copy
[src]

impl<'a, T> ExactSizeIterator for RChunksExact<'a, T>[src]

impl<A> ExactSizeIterator for tract_nnef::internal::tract_downcast_rs::__std::option::IntoIter<A>[src]

impl<A> ExactSizeIterator for tract_nnef::internal::tract_itertools::RepeatN<A> where
    A: Clone
[src]

impl<A> ExactSizeIterator for tract_nnef::internal::tract_itertools::Zip<(A,)> where
    A: ExactSizeIterator
[src]

impl<A, B> ExactSizeIterator for tract_nnef::internal::tract_downcast_rs::__std::iter::Zip<A, B> where
    A: ExactSizeIterator,
    B: ExactSizeIterator
[src]

impl<A, B> ExactSizeIterator for tract_nnef::internal::tract_itertools::Zip<(A, B)> where
    A: ExactSizeIterator,
    B: ExactSizeIterator
[src]

impl<A, B, C> ExactSizeIterator for tract_nnef::internal::tract_itertools::Zip<(A, B, C)> where
    A: ExactSizeIterator,
    B: ExactSizeIterator,
    C: ExactSizeIterator
[src]

impl<A, B, C, D> ExactSizeIterator for tract_nnef::internal::tract_itertools::Zip<(A, B, C, D)> where
    A: ExactSizeIterator,
    B: ExactSizeIterator,
    C: ExactSizeIterator,
    D: ExactSizeIterator
[src]

impl<A, B, C, D, E> ExactSizeIterator for tract_nnef::internal::tract_itertools::Zip<(A, B, C, D, E)> where
    A: ExactSizeIterator,
    B: ExactSizeIterator,
    C: ExactSizeIterator,
    D: ExactSizeIterator,
    E: ExactSizeIterator
[src]

impl<A, B, C, D, E, F> ExactSizeIterator for tract_nnef::internal::tract_itertools::Zip<(A, B, C, D, E, F)> where
    A: ExactSizeIterator,
    B: ExactSizeIterator,
    C: ExactSizeIterator,
    D: ExactSizeIterator,
    E: ExactSizeIterator,
    F: ExactSizeIterator
[src]

impl<A, B, C, D, E, F, G> ExactSizeIterator for tract_nnef::internal::tract_itertools::Zip<(A, B, C, D, E, F, G)> where
    A: ExactSizeIterator,
    B: ExactSizeIterator,
    C: ExactSizeIterator,
    D: ExactSizeIterator,
    E: ExactSizeIterator,
    F: ExactSizeIterator,
    G: ExactSizeIterator
[src]

impl<A, B, C, D, E, F, G, H> ExactSizeIterator for tract_nnef::internal::tract_itertools::Zip<(A, B, C, D, E, F, G, H)> where
    A: ExactSizeIterator,
    B: ExactSizeIterator,
    C: ExactSizeIterator,
    D: ExactSizeIterator,
    E: ExactSizeIterator,
    F: ExactSizeIterator,
    G: ExactSizeIterator,
    H: ExactSizeIterator
[src]

impl<A, F> ExactSizeIterator for OnceWith<F> where
    F: FnOnce() -> A, 
[src]

impl<B, I, F> ExactSizeIterator for Map<I, F> where
    F: FnMut(<I as Iterator>::Item) -> B,
    I: ExactSizeIterator
[src]

impl<D> ExactSizeIterator for IndicesIter<D> where
    D: Dimension
[src]

impl<I> ExactSizeIterator for Box<I> where
    I: ExactSizeIterator + ?Sized
[src]

impl<I> ExactSizeIterator for Enumerate<I> where
    I: ExactSizeIterator
[src]

impl<I> ExactSizeIterator for Fuse<I> where
    I: ExactSizeIterator
[src]

impl<I> ExactSizeIterator for Peekable<I> where
    I: ExactSizeIterator
[src]

impl<I> ExactSizeIterator for Rev<I> where
    I: ExactSizeIterator + DoubleEndedIterator
[src]

impl<I> ExactSizeIterator for Skip<I> where
    I: ExactSizeIterator
[src]

impl<I> ExactSizeIterator for StepBy<I> where
    I: ExactSizeIterator
[src]

impl<I> ExactSizeIterator for Take<I> where
    I: ExactSizeIterator
[src]

impl<I> ExactSizeIterator for tract_nnef::internal::tract_itertools::ExactlyOneError<I> where
    I: ExactSizeIterator
[src]

impl<I> ExactSizeIterator for MultiPeek<I> where
    I: ExactSizeIterator
[src]

impl<I> ExactSizeIterator for tract_nnef::internal::tract_itertools::Step<I> where
    I: ExactSizeIterator
[src]

impl<I> ExactSizeIterator for Tee<I> where
    I: ExactSizeIterator,
    <I as Iterator>::Item: Clone
[src]

impl<I> ExactSizeIterator for tract_nnef::internal::tract_itertools::WithPosition<I> where
    I: ExactSizeIterator
[src]

impl<I, F> ExactSizeIterator for Inspect<I, F> where
    F: FnMut(&<I as Iterator>::Item),
    I: ExactSizeIterator
[src]

impl<I, F> ExactSizeIterator for tract_nnef::internal::tract_itertools::PadUsing<I, F> where
    F: FnMut(usize) -> <I as Iterator>::Item,
    I: ExactSizeIterator
[src]

impl<I, F> ExactSizeIterator for tract_nnef::internal::tract_itertools::Update<I, F> where
    F: FnMut(&mut <I as Iterator>::Item),
    I: ExactSizeIterator
[src]

impl<I, J> ExactSizeIterator for tract_nnef::internal::tract_itertools::ZipEq<I, J> where
    I: ExactSizeIterator,
    J: ExactSizeIterator
[src]

impl<I, R> ExactSizeIterator for tract_nnef::internal::tract_itertools::MapInto<I, R> where
    I: ExactSizeIterator,
    <I as Iterator>::Item: Into<R>, 
[src]

impl<K> ExactSizeIterator for tract_nnef::internal::tract_downcast_rs::__std::collections::hash_set::IntoIter<K>[src]

impl<K, V> ExactSizeIterator for tract_nnef::internal::tract_downcast_rs::__std::collections::btree_map::IntoIter<K, V>[src]

impl<K, V> ExactSizeIterator for tract_nnef::internal::tract_downcast_rs::__std::collections::btree_map::IntoKeys<K, V>[src]

impl<K, V> ExactSizeIterator for tract_nnef::internal::tract_downcast_rs::__std::collections::btree_map::IntoValues<K, V>[src]

impl<K, V> ExactSizeIterator for tract_nnef::internal::tract_downcast_rs::__std::collections::hash_map::IntoIter<K, V>[src]

impl<K, V> ExactSizeIterator for tract_nnef::internal::tract_downcast_rs::__std::collections::hash_map::IntoKeys<K, V>[src]

impl<K, V> ExactSizeIterator for tract_nnef::internal::tract_downcast_rs::__std::collections::hash_map::IntoValues<K, V>[src]

impl<L, R> ExactSizeIterator for Either<L, R> where
    L: ExactSizeIterator,
    R: ExactSizeIterator<Item = <L as Iterator>::Item>, 
[src]

impl<T> ExactSizeIterator for tract_nnef::internal::tract_downcast_rs::__std::collections::binary_heap::IntoIter<T>[src]

impl<T> ExactSizeIterator for IntoIterSorted<T> where
    T: Ord
[src]

impl<T> ExactSizeIterator for tract_nnef::internal::tract_downcast_rs::__std::collections::btree_set::IntoIter<T>[src]

impl<T> ExactSizeIterator for tract_nnef::internal::tract_downcast_rs::__std::collections::linked_list::IntoIter<T>[src]

impl<T> ExactSizeIterator for tract_nnef::internal::tract_downcast_rs::__std::collections::vec_deque::IntoIter<T>[src]

impl<T> ExactSizeIterator for Empty<T>[src]

impl<T> ExactSizeIterator for Once<T>[src]

impl<T> ExactSizeIterator for tract_nnef::internal::tract_downcast_rs::__std::result::IntoIter<T>[src]

impl<T> ExactSizeIterator for tract_nnef::internal::tract_downcast_rs::__std::vec::IntoIter<T>[src]

impl<T> ExactSizeIterator for tract_nnef::internal::tract_itertools::TupleBuffer<T> where
    T: HomogeneousTuple
[src]

impl<T, U> ExactSizeIterator for tract_nnef::internal::tract_itertools::ZipLongest<T, U> where
    T: ExactSizeIterator,
    U: ExactSizeIterator
[src]

impl<T, const N: usize> ExactSizeIterator for tract_nnef::internal::tract_downcast_rs::__std::array::IntoIter<T, N>[src]

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