1.0.0[−][src]Trait tract_hir::prelude::tract_itertools::__std_iter::ExactSizeIterator
An iterator that knows its exact length.
Many Iterator
s 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
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);
Implementations on Foreign Types
impl<'_, K, V> ExactSizeIterator for ValuesMut<'_, K, V>
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impl<'_, K, V> ExactSizeIterator for Values<'_, K, V>
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impl<'_, K, V> ExactSizeIterator for IterMut<'_, K, V>
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impl<'_, K, V> ExactSizeIterator for Drain<'_, K, V>
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impl<'_, K> ExactSizeIterator for Drain<'_, K>
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impl<'_, K, V> ExactSizeIterator for Keys<'_, K, V>
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impl<K, V> ExactSizeIterator for IntoIter<K, V>
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impl<'_, K, V> ExactSizeIterator for Iter<'_, K, V>
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impl ExactSizeIterator for Args
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impl ExactSizeIterator for ArgsOs
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impl<'_, K> ExactSizeIterator for Iter<'_, K>
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impl<K> ExactSizeIterator for IntoIter<K>
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impl ExactSizeIterator for RangeInclusive<u8>
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impl<'a, T> ExactSizeIterator for RChunksExact<'a, T>
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impl<T> ExactSizeIterator for IntoIter<T>
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impl ExactSizeIterator for EscapeUnicode
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impl<A> ExactSizeIterator for IntoIter<A>
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impl<'_, T> ExactSizeIterator for Chunks<'_, T>
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impl ExactSizeIterator for Range<isize>
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impl ExactSizeIterator for RangeInclusive<u16>
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impl<'_, I> ExactSizeIterator for &'_ mut I where
I: ExactSizeIterator + ?Sized,
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I: ExactSizeIterator + ?Sized,
impl<'_, T> ExactSizeIterator for ChunksExact<'_, T>
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impl ExactSizeIterator for Range<i32>
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impl ExactSizeIterator for ToLowercase
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impl<'_, T> ExactSizeIterator for RChunks<'_, T>
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impl<'_, T> ExactSizeIterator for Windows<'_, T>
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impl ExactSizeIterator for EscapeDebug
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impl ExactSizeIterator for RangeInclusive<i16>
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impl ExactSizeIterator for EscapeDefault
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impl ExactSizeIterator for ToUppercase
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impl<'_, T> ExactSizeIterator for Iter<'_, T>
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impl<'_, A> ExactSizeIterator for Iter<'_, A>
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impl<'_, T> ExactSizeIterator for RChunksExactMut<'_, T>
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impl<'_, T> ExactSizeIterator for RChunksMut<'_, T>
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impl<'_> ExactSizeIterator for Bytes<'_>
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impl<const N: usize, T> ExactSizeIterator for IntoIter<T, N> where
[T; N]: LengthAtMost32,
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[T; N]: LengthAtMost32,
impl ExactSizeIterator for Range<i16>
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impl<'_, A> ExactSizeIterator for IterMut<'_, A>
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impl<'_, T> ExactSizeIterator for IterMut<'_, T>
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impl<'_, T> ExactSizeIterator for IterMut<'_, T>
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impl<'_, T> ExactSizeIterator for Iter<'_, T>
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impl ExactSizeIterator for RangeInclusive<i8>
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impl ExactSizeIterator for EscapeDefault
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impl<'_, T> ExactSizeIterator for ChunksMut<'_, T>
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impl<'_, T> ExactSizeIterator for ChunksExactMut<'_, T>
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impl ExactSizeIterator for Range<u32>
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impl ExactSizeIterator for Range<usize>
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impl ExactSizeIterator for Range<i8>
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impl ExactSizeIterator for Range<u16>
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impl ExactSizeIterator for Range<u8>
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impl<'_, T> ExactSizeIterator for DrainSorted<'_, T> where
T: Ord,
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T: Ord,
impl<T> ExactSizeIterator for IntoIter<T>
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impl<'_, K, V> ExactSizeIterator for Keys<'_, K, V>
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impl<'_, T> ExactSizeIterator for IterMut<'_, T>
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impl<T> ExactSizeIterator for IntoIter<T>
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impl<T> ExactSizeIterator for IntoIter<T>
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impl<K, V> ExactSizeIterator for IntoIter<K, V>
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impl<'_, K, V> ExactSizeIterator for IterMut<'_, K, V>
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impl<'_, K, V> ExactSizeIterator for ValuesMut<'_, K, V>
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impl<T> ExactSizeIterator for IntoIter<T>
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impl<'_, K, V> ExactSizeIterator for Iter<'_, K, V>
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impl<'_, T> ExactSizeIterator for Drain<'_, T>
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impl<T> ExactSizeIterator for IntoIter<T>
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impl<'_, T> ExactSizeIterator for Iter<'_, T>
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impl<'_, I> ExactSizeIterator for Splice<'_, I> where
I: Iterator,
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I: Iterator,
impl<'_, T> ExactSizeIterator for Iter<'_, T>
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impl<T> ExactSizeIterator for IntoIterSorted<T> where
T: Ord,
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T: Ord,
impl<'_, T> ExactSizeIterator for Drain<'_, T>
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impl<'_, T> ExactSizeIterator for Drain<'_, T>
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impl<I> ExactSizeIterator for Box<I> where
I: ExactSizeIterator + ?Sized,
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I: ExactSizeIterator + ?Sized,
impl<'_, T> ExactSizeIterator for Iter<'_, T>
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impl<'_, K, V> ExactSizeIterator for Values<'_, K, V>
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impl<'_, T> ExactSizeIterator for IterMut<'_, T>
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impl<'_, T> ExactSizeIterator for Iter<'_, T>
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impl<'_, K, V> ExactSizeIterator for ValuesMut<'_, K, V>
impl<'_, K, V> ExactSizeIterator for IterMut<'_, K, V>
impl<K> ExactSizeIterator for IntoIter<K>
impl<'_, K, V> ExactSizeIterator for Iter<'_, K, V>
impl<'_, K, V> ExactSizeIterator for Values<'_, K, V>
impl<K, V> ExactSizeIterator for IntoIter<K, V>
impl<'_, K, V> ExactSizeIterator for Keys<'_, K, V>
impl<'a, K> ExactSizeIterator for Iter<'a, K>
impl<'_, K> ExactSizeIterator for Drain<'_, K>
impl<'_, K, V> ExactSizeIterator for Drain<'_, K, V>
impl<'a, B> ExactSizeIterator for Iter<'a, B> where
B: BitBlock,
B: BitBlock,
impl<'a, B> ExactSizeIterator for Blocks<'a, B> where
B: BitBlock,
B: BitBlock,
impl<B> ExactSizeIterator for IntoIter<B> where
B: BitBlock,
B: BitBlock,
impl<A, B, C, D> ExactSizeIterator for Zip<(A, B, C, D)> where
A: ExactSizeIterator,
B: ExactSizeIterator,
C: ExactSizeIterator,
D: ExactSizeIterator,
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A: ExactSizeIterator,
B: ExactSizeIterator,
C: ExactSizeIterator,
D: ExactSizeIterator,
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,
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A: ExactSizeIterator,
B: ExactSizeIterator,
C: ExactSizeIterator,
D: ExactSizeIterator,
E: ExactSizeIterator,
F: ExactSizeIterator,
impl<T> ExactSizeIterator for TupleBuffer<T> where
T: TupleCollect,
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T: TupleCollect,
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,
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A: ExactSizeIterator,
B: ExactSizeIterator,
C: ExactSizeIterator,
D: ExactSizeIterator,
E: ExactSizeIterator,
F: ExactSizeIterator,
G: ExactSizeIterator,
impl<I, J> ExactSizeIterator for ZipEq<I, J> where
I: ExactSizeIterator,
J: ExactSizeIterator,
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I: ExactSizeIterator,
J: ExactSizeIterator,
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,
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A: ExactSizeIterator,
B: ExactSizeIterator,
C: ExactSizeIterator,
D: ExactSizeIterator,
E: ExactSizeIterator,
F: ExactSizeIterator,
G: ExactSizeIterator,
H: ExactSizeIterator,
impl<I, R> ExactSizeIterator for MapInto<I, R> where
I: ExactSizeIterator,
<I as Iterator>::Item: Into<R>,
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I: ExactSizeIterator,
<I as Iterator>::Item: Into<R>,
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,
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A: ExactSizeIterator,
B: ExactSizeIterator,
C: ExactSizeIterator,
D: ExactSizeIterator,
E: ExactSizeIterator,
impl<A, B, C> ExactSizeIterator for Zip<(A, B, C)> where
A: ExactSizeIterator,
B: ExactSizeIterator,
C: ExactSizeIterator,
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A: ExactSizeIterator,
B: ExactSizeIterator,
C: ExactSizeIterator,
impl<T, U> ExactSizeIterator for ZipLongest<T, U> where
T: ExactSizeIterator,
U: ExactSizeIterator,
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T: ExactSizeIterator,
U: ExactSizeIterator,
impl<A, B> ExactSizeIterator for Zip<(A, B)> where
A: ExactSizeIterator,
B: ExactSizeIterator,
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A: ExactSizeIterator,
B: ExactSizeIterator,
impl<A> ExactSizeIterator for Zip<(A,)> where
A: ExactSizeIterator,
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A: ExactSizeIterator,
impl<I> ExactSizeIterator for ExactlyOneError<I> where
I: ExactSizeIterator,
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I: ExactSizeIterator,
impl<I, F> ExactSizeIterator for PadUsing<I, F> where
F: FnMut(usize) -> <I as Iterator>::Item,
I: ExactSizeIterator,
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F: FnMut(usize) -> <I as Iterator>::Item,
I: ExactSizeIterator,
impl<I, F> ExactSizeIterator for Update<I, F> where
F: FnMut(&mut <I as Iterator>::Item),
I: ExactSizeIterator,
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F: FnMut(&mut <I as Iterator>::Item),
I: ExactSizeIterator,
impl<I> ExactSizeIterator for Step<I> where
I: ExactSizeIterator,
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I: ExactSizeIterator,
impl<I> ExactSizeIterator for WithPosition<I> where
I: ExactSizeIterator,
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I: ExactSizeIterator,
impl<A> ExactSizeIterator for RepeatN<A> where
A: Clone,
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A: Clone,
impl<'a, T> ExactSizeIterator for Drain<'a, T> where
T: Array,
T: Array,
impl<A> ExactSizeIterator for IntoIter<A> where
A: Array,
Loading content...
A: Array,
Implementors
impl<'a, A, D> ExactSizeIterator for AxisChunksIter<'a, A, D> where
D: Dimension,
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D: Dimension,
impl<'a, A, D> ExactSizeIterator for AxisChunksIterMut<'a, A, D> where
D: Dimension,
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D: Dimension,
impl<'a, A, D> ExactSizeIterator for AxisIter<'a, A, D> where
D: Dimension,
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D: Dimension,
impl<'a, A, D> ExactSizeIterator for AxisIterMut<'a, A, D> where
D: Dimension,
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D: Dimension,
impl<'a, A, D> ExactSizeIterator for IndexedIter<'a, A, D> where
D: Dimension,
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D: Dimension,
impl<'a, A, D> ExactSizeIterator for IndexedIterMut<'a, A, D> where
D: Dimension,
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D: Dimension,
impl<'a, A, D> ExactSizeIterator for tract_hir::internal::tract_ndarray::iter::Iter<'a, A, D> where
D: Dimension,
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D: Dimension,
impl<'a, A, D> ExactSizeIterator for tract_hir::internal::tract_ndarray::iter::IterMut<'a, A, D> where
D: Dimension,
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D: Dimension,
impl<'a, A, D> ExactSizeIterator for LanesIter<'a, A, D> where
D: Dimension,
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D: Dimension,
impl<'a, A, D> ExactSizeIterator for LanesIterMut<'a, A, D> where
D: Dimension,
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D: Dimension,
impl<'a, I, T> ExactSizeIterator for Cloned<I> where
I: ExactSizeIterator<Item = &'a T>,
T: 'a + Clone,
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I: ExactSizeIterator<Item = &'a T>,
T: 'a + Clone,
impl<'a, I, T> ExactSizeIterator for Copied<I> where
I: ExactSizeIterator<Item = &'a T>,
T: 'a + Copy,
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I: ExactSizeIterator<Item = &'a T>,
T: 'a + Copy,
impl<A> ExactSizeIterator for tract_hir::internal::tract_itertools::RepeatN<A> where
A: Clone,
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A: Clone,
impl<A> ExactSizeIterator for tract_hir::internal::tract_itertools::Zip<(A,)> where
A: ExactSizeIterator,
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A: ExactSizeIterator,
impl<A, B> ExactSizeIterator for tract_hir::internal::tract_itertools::__std_iter::Zip<A, B> where
A: ExactSizeIterator,
B: ExactSizeIterator,
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A: ExactSizeIterator,
B: ExactSizeIterator,
impl<A, B> ExactSizeIterator for tract_hir::internal::tract_itertools::Zip<(A, B)> where
A: ExactSizeIterator,
B: ExactSizeIterator,
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A: ExactSizeIterator,
B: ExactSizeIterator,
impl<A, B, C> ExactSizeIterator for tract_hir::internal::tract_itertools::Zip<(A, B, C)> where
A: ExactSizeIterator,
B: ExactSizeIterator,
C: ExactSizeIterator,
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A: ExactSizeIterator,
B: ExactSizeIterator,
C: ExactSizeIterator,
impl<A, B, C, D> ExactSizeIterator for tract_hir::internal::tract_itertools::Zip<(A, B, C, D)> where
A: ExactSizeIterator,
B: ExactSizeIterator,
C: ExactSizeIterator,
D: ExactSizeIterator,
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A: ExactSizeIterator,
B: ExactSizeIterator,
C: ExactSizeIterator,
D: ExactSizeIterator,
impl<A, B, C, D, E> ExactSizeIterator for tract_hir::internal::tract_itertools::Zip<(A, B, C, D, E)> where
A: ExactSizeIterator,
B: ExactSizeIterator,
C: ExactSizeIterator,
D: ExactSizeIterator,
E: ExactSizeIterator,
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A: ExactSizeIterator,
B: ExactSizeIterator,
C: ExactSizeIterator,
D: ExactSizeIterator,
E: ExactSizeIterator,
impl<A, B, C, D, E, F> ExactSizeIterator for tract_hir::internal::tract_itertools::Zip<(A, B, C, D, E, F)> where
A: ExactSizeIterator,
B: ExactSizeIterator,
C: ExactSizeIterator,
D: ExactSizeIterator,
E: ExactSizeIterator,
F: ExactSizeIterator,
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A: ExactSizeIterator,
B: ExactSizeIterator,
C: ExactSizeIterator,
D: ExactSizeIterator,
E: ExactSizeIterator,
F: ExactSizeIterator,
impl<A, B, C, D, E, F, G> ExactSizeIterator for tract_hir::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,
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A: ExactSizeIterator,
B: ExactSizeIterator,
C: ExactSizeIterator,
D: ExactSizeIterator,
E: ExactSizeIterator,
F: ExactSizeIterator,
G: ExactSizeIterator,
impl<A, B, C, D, E, F, G, H> ExactSizeIterator for tract_hir::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,
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A: ExactSizeIterator,
B: ExactSizeIterator,
C: ExactSizeIterator,
D: ExactSizeIterator,
E: ExactSizeIterator,
F: ExactSizeIterator,
G: ExactSizeIterator,
H: ExactSizeIterator,
impl<A, F> ExactSizeIterator for OnceWith<F> where
F: FnOnce() -> A,
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F: FnOnce() -> A,
impl<B, I, F> ExactSizeIterator for Map<I, F> where
F: FnMut(<I as Iterator>::Item) -> B,
I: ExactSizeIterator,
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F: FnMut(<I as Iterator>::Item) -> B,
I: ExactSizeIterator,
impl<D> ExactSizeIterator for IndicesIter<D> where
D: Dimension,
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D: Dimension,
impl<I> ExactSizeIterator for Enumerate<I> where
I: ExactSizeIterator,
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I: ExactSizeIterator,
impl<I> ExactSizeIterator for Fuse<I> where
I: ExactSizeIterator,
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I: ExactSizeIterator,
impl<I> ExactSizeIterator for Peekable<I> where
I: ExactSizeIterator,
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I: ExactSizeIterator,
impl<I> ExactSizeIterator for Rev<I> where
I: ExactSizeIterator + DoubleEndedIterator,
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I: ExactSizeIterator + DoubleEndedIterator,
impl<I> ExactSizeIterator for Skip<I> where
I: ExactSizeIterator,
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I: ExactSizeIterator,
impl<I> ExactSizeIterator for StepBy<I> where
I: ExactSizeIterator,
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I: ExactSizeIterator,
impl<I> ExactSizeIterator for Take<I> where
I: ExactSizeIterator,
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I: ExactSizeIterator,
impl<I> ExactSizeIterator for tract_hir::internal::tract_itertools::ExactlyOneError<I> where
I: ExactSizeIterator,
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I: ExactSizeIterator,
impl<I> ExactSizeIterator for MultiPeek<I> where
I: ExactSizeIterator,
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I: ExactSizeIterator,
impl<I> ExactSizeIterator for tract_hir::internal::tract_itertools::Step<I> where
I: ExactSizeIterator,
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I: ExactSizeIterator,
impl<I> ExactSizeIterator for Tee<I> where
I: ExactSizeIterator,
<I as Iterator>::Item: Clone,
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I: ExactSizeIterator,
<I as Iterator>::Item: Clone,
impl<I> ExactSizeIterator for tract_hir::internal::tract_itertools::WithPosition<I> where
I: ExactSizeIterator,
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I: ExactSizeIterator,
impl<I, F> ExactSizeIterator for Inspect<I, F> where
F: FnMut(&<I as Iterator>::Item),
I: ExactSizeIterator,
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F: FnMut(&<I as Iterator>::Item),
I: ExactSizeIterator,
impl<I, F> ExactSizeIterator for tract_hir::internal::tract_itertools::PadUsing<I, F> where
F: FnMut(usize) -> <I as Iterator>::Item,
I: ExactSizeIterator,
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F: FnMut(usize) -> <I as Iterator>::Item,
I: ExactSizeIterator,
impl<I, F> ExactSizeIterator for tract_hir::internal::tract_itertools::Update<I, F> where
F: FnMut(&mut <I as Iterator>::Item),
I: ExactSizeIterator,
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F: FnMut(&mut <I as Iterator>::Item),
I: ExactSizeIterator,
impl<I, J> ExactSizeIterator for tract_hir::internal::tract_itertools::ZipEq<I, J> where
I: ExactSizeIterator,
J: ExactSizeIterator,
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I: ExactSizeIterator,
J: ExactSizeIterator,
impl<I, R> ExactSizeIterator for tract_hir::internal::tract_itertools::MapInto<I, R> where
I: ExactSizeIterator,
<I as Iterator>::Item: Into<R>,
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I: ExactSizeIterator,
<I as Iterator>::Item: Into<R>,
impl<L, R> ExactSizeIterator for Either<L, R> where
L: ExactSizeIterator,
R: ExactSizeIterator<Item = <L as Iterator>::Item>,
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L: ExactSizeIterator,
R: ExactSizeIterator<Item = <L as Iterator>::Item>,
impl<T> ExactSizeIterator for Empty<T>
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impl<T> ExactSizeIterator for Once<T>
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impl<T> ExactSizeIterator for tract_hir::internal::tract_itertools::TupleBuffer<T> where
T: HomogeneousTuple,
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T: HomogeneousTuple,
impl<T, U> ExactSizeIterator for tract_hir::internal::tract_itertools::ZipLongest<T, U> where
T: ExactSizeIterator,
U: ExactSizeIterator,
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T: ExactSizeIterator,
U: ExactSizeIterator,