Trait rustc_ap_rustc_data_structures::sync::ParallelIterator

#[must_use = "iterators are lazy and do nothing unless consumed"]
pub trait ParallelIterator {
    type Item;
    fn next(&mut self) -> Option<Self::Item>;

    fn size_hint(&self) -> (usize, Option<usize>) { ... }
    fn count(self) -> usize { ... }
    fn last(self) -> Option<Self::Item> { ... }
    fn nth(&mut self, n: usize) -> Option<Self::Item> { ... }
    fn step_by(self, step: usize) -> StepBy<Self> { ... }
    fn chain<U>(self, other: U) -> Chain<Self, <U as IntoIterator>::IntoIter>
    where
        U: IntoIterator<Item = Self::Item>,
    { ... }
    fn zip<U>(self, other: U) -> Zip<Self, <U as IntoIterator>::IntoIter>
    where
        U: IntoIterator,
    { ... }
    fn map<B, F>(self, f: F) -> Map<Self, F>
    where
        F: FnMut(Self::Item) -> B,
    { ... }
    fn for_each<F>(self, f: F)
    where
        F: FnMut(Self::Item),
    { ... }
    fn filter<P>(self, predicate: P) -> Filter<Self, P>
    where
        P: FnMut(&Self::Item) -> bool,
    { ... }
    fn filter_map<B, F>(self, f: F) -> FilterMap<Self, F>
    where
        F: FnMut(Self::Item) -> Option<B>,
    { ... }
    fn enumerate(self) -> Enumerate<Self> { ... }
    fn peekable(self) -> Peekable<Self> { ... }
    fn skip_while<P>(self, predicate: P) -> SkipWhile<Self, P>
    where
        P: FnMut(&Self::Item) -> bool,
    { ... }
    fn take_while<P>(self, predicate: P) -> TakeWhile<Self, P>
    where
        P: FnMut(&Self::Item) -> bool,
    { ... }
    fn map_while<B, P>(self, predicate: P) -> MapWhile<Self, P>
    where
        P: FnMut(Self::Item) -> Option<B>,
    { ... }
    fn skip(self, n: usize) -> Skip<Self> { ... }
    fn take(self, n: usize) -> Take<Self> { ... }
    fn scan<St, B, F>(self, initial_state: St, f: F) -> Scan<Self, St, F>
    where
        F: FnMut(&mut St, Self::Item) -> Option<B>,
    { ... }
    fn flat_map<U, F>(self, f: F) -> FlatMap<Self, U, F>
    where
        F: FnMut(Self::Item) -> U,
        U: IntoIterator,
    { ... }
    fn flatten(self) -> Flatten<Self>
    where
        Self::Item: IntoIterator,
    { ... }
    fn fuse(self) -> Fuse<Self> { ... }
    fn inspect<F>(self, f: F) -> Inspect<Self, F>
    where
        F: FnMut(&Self::Item),
    { ... }
    fn by_ref(&mut self) -> &mut Self { ... }
#[must_use = "if you really need to exhaust the iterator, consider `.for_each(drop)` instead"]
    fn collect<B>(self) -> B
    where
        B: FromIterator<Self::Item>,
    { ... }
    fn partition<B, F>(self, f: F) -> (B, B)
    where
        B: Default + Extend<Self::Item>,
        F: FnMut(&Self::Item) -> bool,
    { ... }
    fn partition_in_place<'a, T, P>(self, predicate: P) -> usize
    where
        P: FnMut(&T) -> bool,
        Self: DoubleEndedIterator<Item = &'a mut T>,
        T: 'a,
    { ... }
    fn is_partitioned<P>(self, predicate: P) -> bool
    where
        P: FnMut(Self::Item) -> bool,
    { ... }
    fn try_fold<B, F, R>(&mut self, init: B, f: F) -> R
    where
        F: FnMut(B, Self::Item) -> R,
        R: Try<Ok = B>,
    { ... }
    fn try_for_each<F, R>(&mut self, f: F) -> R
    where
        F: FnMut(Self::Item) -> R,
        R: Try<Ok = ()>,
    { ... }
    fn fold<B, F>(self, init: B, f: F) -> B
    where
        F: FnMut(B, Self::Item) -> B,
    { ... }
    fn all<F>(&mut self, f: F) -> bool
    where
        F: FnMut(Self::Item) -> bool,
    { ... }
    fn any<F>(&mut self, f: F) -> bool
    where
        F: FnMut(Self::Item) -> bool,
    { ... }
    fn find<P>(&mut self, predicate: P) -> Option<Self::Item>
    where
        P: FnMut(&Self::Item) -> bool,
    { ... }
    fn find_map<B, F>(&mut self, f: F) -> Option<B>
    where
        F: FnMut(Self::Item) -> Option<B>,
    { ... }
    fn try_find<F, E, R>(&mut self, f: F) -> Result<Option<Self::Item>, E>
    where
        F: FnMut(&Self::Item) -> R,
        R: Try<Ok = bool, Error = E>,
    { ... }
    fn position<P>(&mut self, predicate: P) -> Option<usize>
    where
        P: FnMut(Self::Item) -> bool,
    { ... }
    fn rposition<P>(&mut self, predicate: P) -> Option<usize>
    where
        P: FnMut(Self::Item) -> bool,
        Self: ExactSizeIterator + DoubleEndedIterator,
    { ... }
    fn max(self) -> Option<Self::Item>
    where
        Self::Item: Ord,
    { ... }
    fn min(self) -> Option<Self::Item>
    where
        Self::Item: Ord,
    { ... }
    fn max_by_key<B, F>(self, f: F) -> Option<Self::Item>
    where
        B: Ord,
        F: FnMut(&Self::Item) -> B,
    { ... }
    fn max_by<F>(self, compare: F) -> Option<Self::Item>
    where
        F: FnMut(&Self::Item, &Self::Item) -> Ordering,
    { ... }
    fn min_by_key<B, F>(self, f: F) -> Option<Self::Item>
    where
        B: Ord,
        F: FnMut(&Self::Item) -> B,
    { ... }
    fn min_by<F>(self, compare: F) -> Option<Self::Item>
    where
        F: FnMut(&Self::Item, &Self::Item) -> Ordering,
    { ... }
    fn rev(self) -> Rev<Self>
    where
        Self: DoubleEndedIterator,
    { ... }
    fn unzip<A, B, FromA, FromB>(self) -> (FromA, FromB)
    where
        FromA: Default + Extend<A>,
        FromB: Default + Extend<B>,
        Self: Iterator<Item = (A, B)>,
    { ... }
    fn copied<'a, T>(self) -> Copied<Self>
    where
        Self: Iterator<Item = &'a T>,
        T: 'a + Copy,
    { ... }
    fn cloned<'a, T>(self) -> Cloned<Self>
    where
        Self: Iterator<Item = &'a T>,
        T: 'a + Clone,
    { ... }
    fn cycle(self) -> Cycle<Self>
    where
        Self: Clone,
    { ... }
    fn sum<S>(self) -> S
    where
        S: Sum<Self::Item>,
    { ... }
    fn product<P>(self) -> P
    where
        P: Product<Self::Item>,
    { ... }
    fn cmp<I>(self, other: I) -> Ordering
    where
        I: IntoIterator<Item = Self::Item>,
        Self::Item: Ord,
    { ... }
    fn cmp_by<I, F>(self, other: I, cmp: F) -> Ordering
    where
        F: FnMut(Self::Item, <I as IntoIterator>::Item) -> Ordering,
        I: IntoIterator,
    { ... }
    fn partial_cmp<I>(self, other: I) -> Option<Ordering>
    where
        I: IntoIterator,
        Self::Item: PartialOrd<<I as IntoIterator>::Item>,
    { ... }
    fn partial_cmp_by<I, F>(self, other: I, partial_cmp: F) -> Option<Ordering>
    where
        F: FnMut(Self::Item, <I as IntoIterator>::Item) -> Option<Ordering>,
        I: IntoIterator,
    { ... }
    fn eq<I>(self, other: I) -> bool
    where
        I: IntoIterator,
        Self::Item: PartialEq<<I as IntoIterator>::Item>,
    { ... }
    fn eq_by<I, F>(self, other: I, eq: F) -> bool
    where
        F: FnMut(Self::Item, <I as IntoIterator>::Item) -> bool,
        I: IntoIterator,
    { ... }
    fn ne<I>(self, other: I) -> bool
    where
        I: IntoIterator,
        Self::Item: PartialEq<<I as IntoIterator>::Item>,
    { ... }
    fn lt<I>(self, other: I) -> bool
    where
        I: IntoIterator,
        Self::Item: PartialOrd<<I as IntoIterator>::Item>,
    { ... }
    fn le<I>(self, other: I) -> bool
    where
        I: IntoIterator,
        Self::Item: PartialOrd<<I as IntoIterator>::Item>,
    { ... }
    fn gt<I>(self, other: I) -> bool
    where
        I: IntoIterator,
        Self::Item: PartialOrd<<I as IntoIterator>::Item>,
    { ... }
    fn ge<I>(self, other: I) -> bool
    where
        I: IntoIterator,
        Self::Item: PartialOrd<<I as IntoIterator>::Item>,
    { ... }
    fn is_sorted(self) -> bool
    where
        Self::Item: PartialOrd<Self::Item>,
    { ... }
    fn is_sorted_by<F>(self, compare: F) -> bool
    where
        F: FnMut(&Self::Item, &Self::Item) -> Option<Ordering>,
    { ... }
    fn is_sorted_by_key<F, K>(self, f: F) -> bool
    where
        F: FnMut(Self::Item) -> K,
        K: PartialOrd<K>,
    { ... }
}

An interface for dealing with iterators.

This is the main iterator trait. For more about the concept of iterators generally, please see the module-level documentation. In particular, you may want to know how to implement Iterator.

Associated Types

type Item

The type of the elements being iterated over.

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Required methods

fn next(&mut self) -> Option<Self::Item>

Advances the iterator and returns the next value.

Returns None when iteration is finished. Individual iterator implementations may choose to resume iteration, and so calling next() again may or may not eventually start returning Some(Item) again at some point.

Examples

Basic usage:

let a = [1, 2, 3];

let mut iter = a.iter();

// A call to next() returns the next value...
assert_eq!(Some(&1), iter.next());
assert_eq!(Some(&2), iter.next());
assert_eq!(Some(&3), iter.next());

// ... and then None once it's over.
assert_eq!(None, iter.next());

// More calls may or may not return `None`. Here, they always will.
assert_eq!(None, iter.next());
assert_eq!(None, iter.next());

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Provided methods

fn size_hint(&self) -> (usize, Option<usize>)

Returns the bounds on the remaining length of the iterator.

Specifically, size_hint() returns a tuple where the first element is the lower bound, and the second element is the upper bound.

The second half of the tuple that is returned is an Option<usize>. A None here means that either there is no known upper bound, or the upper bound is larger than usize.

Implementation notes

It is not enforced that an iterator implementation yields the declared number of elements. A buggy iterator may yield less than the lower bound or more than the upper bound of elements.

size_hint() is primarily intended to be used for optimizations such as reserving space for the elements of the iterator, but must not be trusted to e.g., omit bounds checks in unsafe code. An incorrect implementation of size_hint() should not lead to memory safety violations.

That said, the implementation should provide a correct estimation, because otherwise it would be a violation of the trait's protocol.

The default implementation returns (0, None) which is correct for any iterator.

Examples

Basic usage:

let a = [1, 2, 3];
let iter = a.iter();

assert_eq!((3, Some(3)), iter.size_hint());

A more complex example:

// The even numbers from zero to ten.
let iter = (0..10).filter(|x| x % 2 == 0);

// We might iterate from zero to ten times. Knowing that it's five
// exactly wouldn't be possible without executing filter().
assert_eq!((0, Some(10)), iter.size_hint());

// Let's add five more numbers with chain()
let iter = (0..10).filter(|x| x % 2 == 0).chain(15..20);

// now both bounds are increased by five
assert_eq!((5, Some(15)), iter.size_hint());

Returning None for an upper bound:

// an infinite iterator has no upper bound
// and the maximum possible lower bound
let iter = 0..;

assert_eq!((usize::max_value(), None), iter.size_hint());

fn count(self) -> usize

Consumes the iterator, counting the number of iterations and returning it.

This method will call next repeatedly until None is encountered, returning the number of times it saw Some. Note that next has to be called at least once even if the iterator does not have any elements.

Overflow Behavior

The method does no guarding against overflows, so counting elements of an iterator with more than usize::MAX elements either produces the wrong result or panics. If debug assertions are enabled, a panic is guaranteed.

Panics

This function might panic if the iterator has more than usize::MAX elements.

Examples

Basic usage:

let a = [1, 2, 3];
assert_eq!(a.iter().count(), 3);

let a = [1, 2, 3, 4, 5];
assert_eq!(a.iter().count(), 5);

fn last(self) -> Option<Self::Item>

Consumes the iterator, returning the last element.

This method will evaluate the iterator until it returns None. While doing so, it keeps track of the current element. After None is returned, last() will then return the last element it saw.

Examples

Basic usage:

let a = [1, 2, 3];
assert_eq!(a.iter().last(), Some(&3));

let a = [1, 2, 3, 4, 5];
assert_eq!(a.iter().last(), Some(&5));

fn nth(&mut self, n: usize) -> Option<Self::Item>

Returns the nth element of the iterator.

Like most indexing operations, the count starts from zero, so nth(0) returns the first value, nth(1) the second, and so on.

Note that all preceding elements, as well as the returned element, will be consumed from the iterator. That means that the preceding elements will be discarded, and also that calling nth(0) multiple times on the same iterator will return different elements.

nth() will return None if n is greater than or equal to the length of the iterator.

Examples

Basic usage:

let a = [1, 2, 3];
assert_eq!(a.iter().nth(1), Some(&2));

Calling nth() multiple times doesn't rewind the iterator:

let a = [1, 2, 3];

let mut iter = a.iter();

assert_eq!(iter.nth(1), Some(&2));
assert_eq!(iter.nth(1), None);

Returning None if there are less than n + 1 elements:

let a = [1, 2, 3];
assert_eq!(a.iter().nth(10), None);

Important traits for StepBy<I>

impl<I> Iterator for StepBy<I> where
    I: Iterator,  type Item = <I as Iterator>::Item;

fn step_by(self, step: usize) -> StepBy<Self>

Creates an iterator starting at the same point, but stepping by the given amount at each iteration.

Note 1: The first element of the iterator will always be returned, regardless of the step given.

Note 2: The time at which ignored elements are pulled is not fixed. StepBy behaves like the sequence next(), nth(step-1), nth(step-1), …, but is also free to behave like the sequence advance_n_and_return_first(step), advance_n_and_return_first(step), … Which way is used may change for some iterators for performance reasons. The second way will advance the iterator earlier and may consume more items.

advance_n_and_return_first is the equivalent of:

fn advance_n_and_return_first<I>(iter: &mut I, total_step: usize) -> Option<I::Item>
where
    I: Iterator,
{
    let next = iter.next();
    if total_step > 1 {
        iter.nth(total_step-2);
    }
    next
}

Panics

The method will panic if the given step is 0.

Examples

Basic usage:

let a = [0, 1, 2, 3, 4, 5];
let mut iter = a.iter().step_by(2);

assert_eq!(iter.next(), Some(&0));
assert_eq!(iter.next(), Some(&2));
assert_eq!(iter.next(), Some(&4));
assert_eq!(iter.next(), None);

Important traits for Chain<A, B>

impl<A, B> Iterator for Chain<A, B> where
    A: Iterator,
    B: Iterator<Item = <A as Iterator>::Item>,  type Item = <A as Iterator>::Item;

fn chain<U>(self, other: U) -> Chain<Self, <U as IntoIterator>::IntoIter> where
    U: IntoIterator<Item = Self::Item>, 

Takes two iterators and creates a new iterator over both in sequence.

chain() will return a new iterator which will first iterate over values from the first iterator and then over values from the second iterator.

In other words, it links two iterators together, in a chain. 🔗

once is commonly used to adapt a single value into a chain of other kinds of iteration.

Examples

Basic usage:

let a1 = [1, 2, 3];
let a2 = [4, 5, 6];

let mut iter = a1.iter().chain(a2.iter());

assert_eq!(iter.next(), Some(&1));
assert_eq!(iter.next(), Some(&2));
assert_eq!(iter.next(), Some(&3));
assert_eq!(iter.next(), Some(&4));
assert_eq!(iter.next(), Some(&5));
assert_eq!(iter.next(), Some(&6));
assert_eq!(iter.next(), None);

Since the argument to chain() uses IntoIterator, we can pass anything that can be converted into an Iterator, not just an Iterator itself. For example, slices (&[T]) implement IntoIterator, and so can be passed to chain() directly:

let s1 = &[1, 2, 3];
let s2 = &[4, 5, 6];

let mut iter = s1.iter().chain(s2);

assert_eq!(iter.next(), Some(&1));
assert_eq!(iter.next(), Some(&2));
assert_eq!(iter.next(), Some(&3));
assert_eq!(iter.next(), Some(&4));
assert_eq!(iter.next(), Some(&5));
assert_eq!(iter.next(), Some(&6));
assert_eq!(iter.next(), None);

If you work with Windows API, you may wish to convert OsStr to Vec<u16>:

#[cfg(windows)]
fn os_str_to_utf16(s: &std::ffi::OsStr) -> Vec<u16> {
    use std::os::windows::ffi::OsStrExt;
    s.encode_wide().chain(std::iter::once(0)).collect()
}

Important traits for Zip<A, B>

impl<A, B> Iterator for Zip<A, B> where
    A: Iterator,
    B: Iterator,  type Item = (<A as Iterator>::Item, <B as Iterator>::Item);

fn zip<U>(self, other: U) -> Zip<Self, <U as IntoIterator>::IntoIter> where
    U: IntoIterator, 

'Zips up' two iterators into a single iterator of pairs.

zip() returns a new iterator that will iterate over two other iterators, returning a tuple where the first element comes from the first iterator, and the second element comes from the second iterator.

In other words, it zips two iterators together, into a single one.

If either iterator returns None, next from the zipped iterator will return None. If the first iterator returns None, zip will short-circuit and next will not be called on the second iterator.

Examples

Basic usage:

let a1 = [1, 2, 3];
let a2 = [4, 5, 6];

let mut iter = a1.iter().zip(a2.iter());

assert_eq!(iter.next(), Some((&1, &4)));
assert_eq!(iter.next(), Some((&2, &5)));
assert_eq!(iter.next(), Some((&3, &6)));
assert_eq!(iter.next(), None);

Since the argument to zip() uses IntoIterator, we can pass anything that can be converted into an Iterator, not just an Iterator itself. For example, slices (&[T]) implement IntoIterator, and so can be passed to zip() directly:

let s1 = &[1, 2, 3];
let s2 = &[4, 5, 6];

let mut iter = s1.iter().zip(s2);

assert_eq!(iter.next(), Some((&1, &4)));
assert_eq!(iter.next(), Some((&2, &5)));
assert_eq!(iter.next(), Some((&3, &6)));
assert_eq!(iter.next(), None);

zip() is often used to zip an infinite iterator to a finite one. This works because the finite iterator will eventually return None, ending the zipper. Zipping with (0..) can look a lot like enumerate:

let enumerate: Vec<_> = "foo".chars().enumerate().collect();

let zipper: Vec<_> = (0..).zip("foo".chars()).collect();

assert_eq!((0, 'f'), enumerate[0]);
assert_eq!((0, 'f'), zipper[0]);

assert_eq!((1, 'o'), enumerate[1]);
assert_eq!((1, 'o'), zipper[1]);

assert_eq!((2, 'o'), enumerate[2]);
assert_eq!((2, 'o'), zipper[2]);

Important traits for Map<I, F>

impl<B, I, F> Iterator for Map<I, F> where
    F: FnMut(<I as Iterator>::Item) -> B,
    I: Iterator,  type Item = B;

fn map<B, F>(self, f: F) -> Map<Self, F> where
    F: FnMut(Self::Item) -> B, 

Takes a closure and creates an iterator which calls that closure on each element.

map() transforms one iterator into another, by means of its argument: something that implements FnMut. It produces a new iterator which calls this closure on each element of the original iterator.

If you are good at thinking in types, you can think of map() like this: If you have an iterator that gives you elements of some type A, and you want an iterator of some other type B, you can use map(), passing a closure that takes an A and returns a B.

map() is conceptually similar to a for loop. However, as map() is lazy, it is best used when you're already working with other iterators. If you're doing some sort of looping for a side effect, it's considered more idiomatic to use for than map().

Examples

Basic usage:

let a = [1, 2, 3];

let mut iter = a.iter().map(|x| 2 * x);

assert_eq!(iter.next(), Some(2));
assert_eq!(iter.next(), Some(4));
assert_eq!(iter.next(), Some(6));
assert_eq!(iter.next(), None);

If you're doing some sort of side effect, prefer for to map():

// don't do this:
(0..5).map(|x| println!("{}", x));

// it won't even execute, as it is lazy. Rust will warn you about this.

// Instead, use for:
for x in 0..5 {
    println!("{}", x);
}

fn for_each<F>(self, f: F) where
    F: FnMut(Self::Item), 

Calls a closure on each element of an iterator.

This is equivalent to using a for loop on the iterator, although break and continue are not possible from a closure. It's generally more idiomatic to use a for loop, but for_each may be more legible when processing items at the end of longer iterator chains. In some cases for_each may also be faster than a loop, because it will use internal iteration on adaptors like Chain.

Examples

Basic usage:

use std::sync::mpsc::channel;

let (tx, rx) = channel();
(0..5).map(|x| x * 2 + 1)
      .for_each(move |x| tx.send(x).unwrap());

let v: Vec<_> =  rx.iter().collect();
assert_eq!(v, vec![1, 3, 5, 7, 9]);

For such a small example, a for loop may be cleaner, but for_each might be preferable to keep a functional style with longer iterators:

(0..5).flat_map(|x| x * 100 .. x * 110)
      .enumerate()
      .filter(|&(i, x)| (i + x) % 3 == 0)
      .for_each(|(i, x)| println!("{}:{}", i, x));

Important traits for Filter<I, P>

impl<I, P> Iterator for Filter<I, P> where
    I: Iterator,
    P: FnMut(&<I as Iterator>::Item) -> bool,  type Item = <I as Iterator>::Item;

fn filter<P>(self, predicate: P) -> Filter<Self, P> where
    P: FnMut(&Self::Item) -> bool, 

Creates an iterator which uses a closure to determine if an element should be yielded.

The closure must return true or false. filter() creates an iterator which calls this closure on each element. If the closure returns true, then the element is returned. If the closure returns false, it will try again, and call the closure on the next element, seeing if it passes the test.

Examples

Basic usage:

let a = [0i32, 1, 2];

let mut iter = a.iter().filter(|x| x.is_positive());

assert_eq!(iter.next(), Some(&1));
assert_eq!(iter.next(), Some(&2));
assert_eq!(iter.next(), None);

Because the closure passed to filter() takes a reference, and many iterators iterate over references, this leads to a possibly confusing situation, where the type of the closure is a double reference:

let a = [0, 1, 2];

let mut iter = a.iter().filter(|x| **x > 1); // need two *s!

assert_eq!(iter.next(), Some(&2));
assert_eq!(iter.next(), None);

It's common to instead use destructuring on the argument to strip away one:

let a = [0, 1, 2];

let mut iter = a.iter().filter(|&x| *x > 1); // both & and *

assert_eq!(iter.next(), Some(&2));
assert_eq!(iter.next(), None);

or both:

let a = [0, 1, 2];

let mut iter = a.iter().filter(|&&x| x > 1); // two &s

assert_eq!(iter.next(), Some(&2));
assert_eq!(iter.next(), None);

of these layers.

Important traits for FilterMap<I, F>

impl<B, I, F> Iterator for FilterMap<I, F> where
    F: FnMut(<I as Iterator>::Item) -> Option<B>,
    I: Iterator,  type Item = B;

fn filter_map<B, F>(self, f: F) -> FilterMap<Self, F> where
    F: FnMut(Self::Item) -> Option<B>, 

Creates an iterator that both filters and maps.

The closure must return an Option<T>. filter_map creates an iterator which calls this closure on each element. If the closure returns Some(element), then that element is returned. If the closure returns None, it will try again, and call the closure on the next element, seeing if it will return Some.

Why filter_map and not just filter and map? The key is in this part:

If the closure returns Some(element), then that element is returned.

In other words, it removes the Option<T> layer automatically. If your mapping is already returning an Option<T> and you want to skip over Nones, then filter_map is much, much nicer to use.

Examples

Basic usage:

let a = ["1", "lol", "3", "NaN", "5"];

let mut iter = a.iter().filter_map(|s| s.parse().ok());

assert_eq!(iter.next(), Some(1));
assert_eq!(iter.next(), Some(3));
assert_eq!(iter.next(), Some(5));
assert_eq!(iter.next(), None);

Here's the same example, but with filter and map:

let a = ["1", "lol", "3", "NaN", "5"];
let mut iter = a.iter().map(|s| s.parse()).filter(|s| s.is_ok()).map(|s| s.unwrap());
assert_eq!(iter.next(), Some(1));
assert_eq!(iter.next(), Some(3));
assert_eq!(iter.next(), Some(5));
assert_eq!(iter.next(), None);

Important traits for Enumerate<I>

impl<I> Iterator for Enumerate<I> where
    I: Iterator,  type Item = (usize, <I as Iterator>::Item);

fn enumerate(self) -> Enumerate<Self>

Creates an iterator which gives the current iteration count as well as the next value.

The iterator returned yields pairs (i, val), where i is the current index of iteration and val is the value returned by the iterator.

enumerate() keeps its count as a usize. If you want to count by a different sized integer, the zip function provides similar functionality.

Overflow Behavior

The method does no guarding against overflows, so enumerating more than usize::MAX elements either produces the wrong result or panics. If debug assertions are enabled, a panic is guaranteed.

Panics

The returned iterator might panic if the to-be-returned index would overflow a usize.

Examples

let a = ['a', 'b', 'c'];

let mut iter = a.iter().enumerate();

assert_eq!(iter.next(), Some((0, &'a')));
assert_eq!(iter.next(), Some((1, &'b')));
assert_eq!(iter.next(), Some((2, &'c')));
assert_eq!(iter.next(), None);

Important traits for Peekable<I>

impl<I> Iterator for Peekable<I> where
    I: Iterator,  type Item = <I as Iterator>::Item;

fn peekable(self) -> Peekable<Self>

Creates an iterator which can use peek to look at the next element of the iterator without consuming it.

Adds a peek method to an iterator. See its documentation for more information.

Note that the underlying iterator is still advanced when peek is called for the first time: In order to retrieve the next element, next is called on the underlying iterator, hence any side effects (i.e. anything other than fetching the next value) of the next method will occur.

Examples

Basic usage:

let xs = [1, 2, 3];

let mut iter = xs.iter().peekable();

// peek() lets us see into the future
assert_eq!(iter.peek(), Some(&&1));
assert_eq!(iter.next(), Some(&1));

assert_eq!(iter.next(), Some(&2));

// we can peek() multiple times, the iterator won't advance
assert_eq!(iter.peek(), Some(&&3));
assert_eq!(iter.peek(), Some(&&3));

assert_eq!(iter.next(), Some(&3));

// after the iterator is finished, so is peek()
assert_eq!(iter.peek(), None);
assert_eq!(iter.next(), None);

Important traits for SkipWhile<I, P>

impl<I, P> Iterator for SkipWhile<I, P> where
    I: Iterator,
    P: FnMut(&<I as Iterator>::Item) -> bool,  type Item = <I as Iterator>::Item;

fn skip_while<P>(self, predicate: P) -> SkipWhile<Self, P> where
    P: FnMut(&Self::Item) -> bool, 

Creates an iterator that skips elements based on a predicate.

skip_while() takes a closure as an argument. It will call this closure on each element of the iterator, and ignore elements until it returns false.

After false is returned, skip_while()'s job is over, and the rest of the elements are yielded.

Examples

Basic usage:

let a = [-1i32, 0, 1];

let mut iter = a.iter().skip_while(|x| x.is_negative());

assert_eq!(iter.next(), Some(&0));
assert_eq!(iter.next(), Some(&1));
assert_eq!(iter.next(), None);

Because the closure passed to skip_while() takes a reference, and many iterators iterate over references, this leads to a possibly confusing situation, where the type of the closure is a double reference:

let a = [-1, 0, 1];

let mut iter = a.iter().skip_while(|x| **x < 0); // need two *s!

assert_eq!(iter.next(), Some(&0));
assert_eq!(iter.next(), Some(&1));
assert_eq!(iter.next(), None);

Stopping after an initial false:

let a = [-1, 0, 1, -2];

let mut iter = a.iter().skip_while(|x| **x < 0);

assert_eq!(iter.next(), Some(&0));
assert_eq!(iter.next(), Some(&1));

// while this would have been false, since we already got a false,
// skip_while() isn't used any more
assert_eq!(iter.next(), Some(&-2));

assert_eq!(iter.next(), None);

Important traits for TakeWhile<I, P>

impl<I, P> Iterator for TakeWhile<I, P> where
    I: Iterator,
    P: FnMut(&<I as Iterator>::Item) -> bool,  type Item = <I as Iterator>::Item;

fn take_while<P>(self, predicate: P) -> TakeWhile<Self, P> where
    P: FnMut(&Self::Item) -> bool, 

Creates an iterator that yields elements based on a predicate.

take_while() takes a closure as an argument. It will call this closure on each element of the iterator, and yield elements while it returns true.

After false is returned, take_while()'s job is over, and the rest of the elements are ignored.

Examples

Basic usage:

let a = [-1i32, 0, 1];

let mut iter = a.iter().take_while(|x| x.is_negative());

assert_eq!(iter.next(), Some(&-1));
assert_eq!(iter.next(), None);

Because the closure passed to take_while() takes a reference, and many iterators iterate over references, this leads to a possibly confusing situation, where the type of the closure is a double reference:

let a = [-1, 0, 1];

let mut iter = a.iter().take_while(|x| **x < 0); // need two *s!

assert_eq!(iter.next(), Some(&-1));
assert_eq!(iter.next(), None);

Stopping after an initial false:

let a = [-1, 0, 1, -2];

let mut iter = a.iter().take_while(|x| **x < 0);

assert_eq!(iter.next(), Some(&-1));

// We have more elements that are less than zero, but since we already
// got a false, take_while() isn't used any more
assert_eq!(iter.next(), None);

Because take_while() needs to look at the value in order to see if it should be included or not, consuming iterators will see that it is removed:

let a = [1, 2, 3, 4];
let mut iter = a.iter();

let result: Vec<i32> = iter.by_ref()
                           .take_while(|n| **n != 3)
                           .cloned()
                           .collect();

assert_eq!(result, &[1, 2]);

let result: Vec<i32> = iter.cloned().collect();

assert_eq!(result, &[4]);

The 3 is no longer there, because it was consumed in order to see if the iteration should stop, but wasn't placed back into the iterator.

Important traits for MapWhile<I, P>

impl<B, I, P> Iterator for MapWhile<I, P> where
    I: Iterator,
    P: FnMut(<I as Iterator>::Item) -> Option<B>,  type Item = B;

fn map_while<B, P>(self, predicate: P) -> MapWhile<Self, P> where
    P: FnMut(Self::Item) -> Option<B>, 

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

recently added

Creates an iterator that both yields elements based on a predicate and maps.

map_while() takes a closure as an argument. It will call this closure on each element of the iterator, and yield elements while it returns Some(_).

After None is returned, map_while()'s job is over, and the rest of the elements are ignored.

Examples

Basic usage:

#![feature(iter_map_while)]
let a = [-1i32, 4, 0, 1];

let mut iter = a.iter().map_while(|x| 16i32.checked_div(*x));

assert_eq!(iter.next(), Some(-16));
assert_eq!(iter.next(), Some(4));
assert_eq!(iter.next(), None);

Here's the same example, but with take_while and map:

let a = [-1i32, 4, 0, 1];

let mut iter = a.iter()
                .map(|x| 16i32.checked_div(*x))
                .take_while(|x| x.is_some())
                .map(|x| x.unwrap());

assert_eq!(iter.next(), Some(-16));
assert_eq!(iter.next(), Some(4));
assert_eq!(iter.next(), None);

Stopping after an initial None:

#![feature(iter_map_while)]
use std::convert::TryFrom;

let a = [0, -1, 1, -2];

let mut iter = a.iter().map_while(|x| u32::try_from(*x).ok());

assert_eq!(iter.next(), Some(0u32));

// We have more elements that are fit in u32, but since we already
// got a None, map_while() isn't used any more
assert_eq!(iter.next(), None);

Because map_while() needs to look at the value in order to see if it should be included or not, consuming iterators will see that it is removed:

#![feature(iter_map_while)]
use std::convert::TryFrom;

let a = [1, 2, -3, 4];
let mut iter = a.iter();

let result: Vec<u32> = iter.by_ref()
                           .map_while(|n| u32::try_from(*n).ok())
                           .collect();

assert_eq!(result, &[1, 2]);

let result: Vec<i32> = iter.cloned().collect();

assert_eq!(result, &[4]);

The -3 is no longer there, because it was consumed in order to see if the iteration should stop, but wasn't placed back into the iterator.

Important traits for Skip<I>

impl<I> Iterator for Skip<I> where
    I: Iterator,  type Item = <I as Iterator>::Item;

fn skip(self, n: usize) -> Skip<Self>

Creates an iterator that skips the first n elements.

After they have been consumed, the rest of the elements are yielded. Rather than overriding this method directly, instead override the nth method.

Examples

Basic usage:

let a = [1, 2, 3];

let mut iter = a.iter().skip(2);

assert_eq!(iter.next(), Some(&3));
assert_eq!(iter.next(), None);

Important traits for Take<I>

impl<I> Iterator for Take<I> where
    I: Iterator,  type Item = <I as Iterator>::Item;

fn take(self, n: usize) -> Take<Self>

Creates an iterator that yields its first n elements.

Examples

Basic usage:

let a = [1, 2, 3];

let mut iter = a.iter().take(2);

assert_eq!(iter.next(), Some(&1));
assert_eq!(iter.next(), Some(&2));
assert_eq!(iter.next(), None);

take() is often used with an infinite iterator, to make it finite:

let mut iter = (0..).take(3);

assert_eq!(iter.next(), Some(0));
assert_eq!(iter.next(), Some(1));
assert_eq!(iter.next(), Some(2));
assert_eq!(iter.next(), None);

Important traits for Scan<I, St, F>

impl<B, I, St, F> Iterator for Scan<I, St, F> where
    F: FnMut(&mut St, <I as Iterator>::Item) -> Option<B>,
    I: Iterator,  type Item = B;

fn scan<St, B, F>(self, initial_state: St, f: F) -> Scan<Self, St, F> where
    F: FnMut(&mut St, Self::Item) -> Option<B>, 

An iterator adaptor similar to fold that holds internal state and produces a new iterator.

scan() takes two arguments: an initial value which seeds the internal state, and a closure with two arguments, the first being a mutable reference to the internal state and the second an iterator element. The closure can assign to the internal state to share state between iterations.

On iteration, the closure will be applied to each element of the iterator and the return value from the closure, an Option, is yielded by the iterator.

Examples

Basic usage:

let a = [1, 2, 3];

let mut iter = a.iter().scan(1, |state, &x| {
    // each iteration, we'll multiply the state by the element
    *state = *state * x;

    // then, we'll yield the negation of the state
    Some(-*state)
});

assert_eq!(iter.next(), Some(-1));
assert_eq!(iter.next(), Some(-2));
assert_eq!(iter.next(), Some(-6));
assert_eq!(iter.next(), None);

Important traits for FlatMap<I, U, F>

impl<I, U, F> Iterator for FlatMap<I, U, F> where
    F: FnMut(<I as Iterator>::Item) -> U,
    I: Iterator,
    U: IntoIterator,  type Item = <U as IntoIterator>::Item;

fn flat_map<U, F>(self, f: F) -> FlatMap<Self, U, F> where
    F: FnMut(Self::Item) -> U,
    U: IntoIterator, 

Creates an iterator that works like map, but flattens nested structure.

The map adapter is very useful, but only when the closure argument produces values. If it produces an iterator instead, there's an extra layer of indirection. flat_map() will remove this extra layer on its own.

You can think of flat_map(f) as the semantic equivalent of mapping, and then flattening as in map(f).flatten().

Another way of thinking about flat_map(): map's closure returns one item for each element, and flat_map()'s closure returns an iterator for each element.

Examples

Basic usage:

let words = ["alpha", "beta", "gamma"];

// chars() returns an iterator
let merged: String = words.iter()
                          .flat_map(|s| s.chars())
                          .collect();
assert_eq!(merged, "alphabetagamma");

Important traits for Flatten<I>

impl<I, U> Iterator for Flatten<I> where
    I: Iterator,
    U: Iterator,
    <I as Iterator>::Item: IntoIterator,
    <<I as Iterator>::Item as IntoIterator>::IntoIter == U,
    <<I as Iterator>::Item as IntoIterator>::Item == <U as Iterator>::Item,  type Item = <U as Iterator>::Item;

fn flatten(self) -> Flatten<Self> where
    Self::Item: IntoIterator, 

Creates an iterator that flattens nested structure.

This is useful when you have an iterator of iterators or an iterator of things that can be turned into iterators and you want to remove one level of indirection.

Examples

Basic usage:

let data = vec![vec![1, 2, 3, 4], vec![5, 6]];
let flattened = data.into_iter().flatten().collect::<Vec<u8>>();
assert_eq!(flattened, &[1, 2, 3, 4, 5, 6]);

Mapping and then flattening:

let words = ["alpha", "beta", "gamma"];

// chars() returns an iterator
let merged: String = words.iter()
                          .map(|s| s.chars())
                          .flatten()
                          .collect();
assert_eq!(merged, "alphabetagamma");

You can also rewrite this in terms of flat_map(), which is preferable in this case since it conveys intent more clearly:

let words = ["alpha", "beta", "gamma"];

// chars() returns an iterator
let merged: String = words.iter()
                          .flat_map(|s| s.chars())
                          .collect();
assert_eq!(merged, "alphabetagamma");

Flattening once only removes one level of nesting:

let d3 = [[[1, 2], [3, 4]], [[5, 6], [7, 8]]];

let d2 = d3.iter().flatten().collect::<Vec<_>>();
assert_eq!(d2, [&[1, 2], &[3, 4], &[5, 6], &[7, 8]]);

let d1 = d3.iter().flatten().flatten().collect::<Vec<_>>();
assert_eq!(d1, [&1, &2, &3, &4, &5, &6, &7, &8]);

Here we see that flatten() does not perform a "deep" flatten. Instead, only one level of nesting is removed. That is, if you flatten() a three-dimensional array the result will be two-dimensional and not one-dimensional. To get a one-dimensional structure, you have to flatten() again.

Important traits for Fuse<I>

impl<I> Iterator for Fuse<I> where
    I: Iterator,  type Item = <I as Iterator>::Item;impl<I> Iterator for Fuse<I> where
    I: FusedIterator, 

fn fuse(self) -> Fuse<Self>

Creates an iterator which ends after the first None.

After an iterator returns None, future calls may or may not yield Some(T) again. fuse() adapts an iterator, ensuring that after a None is given, it will always return None forever.

Examples

Basic usage:

// an iterator which alternates between Some and None
struct Alternate {
    state: i32,
}

impl Iterator for Alternate {
    type Item = i32;

    fn next(&mut self) -> Option<i32> {
        let val = self.state;
        self.state = self.state + 1;

        // if it's even, Some(i32), else None
        if val % 2 == 0 {
            Some(val)
        } else {
            None
        }
    }
}

let mut iter = Alternate { state: 0 };

// we can see our iterator going back and forth
assert_eq!(iter.next(), Some(0));
assert_eq!(iter.next(), None);
assert_eq!(iter.next(), Some(2));
assert_eq!(iter.next(), None);

// however, once we fuse it...
let mut iter = iter.fuse();

assert_eq!(iter.next(), Some(4));
assert_eq!(iter.next(), None);

// it will always return `None` after the first time.
assert_eq!(iter.next(), None);
assert_eq!(iter.next(), None);
assert_eq!(iter.next(), None);

Important traits for Inspect<I, F>

impl<I, F> Iterator for Inspect<I, F> where
    F: FnMut(&<I as Iterator>::Item),
    I: Iterator,  type Item = <I as Iterator>::Item;

fn inspect<F>(self, f: F) -> Inspect<Self, F> where
    F: FnMut(&Self::Item), 

Does something with each element of an iterator, passing the value on.

When using iterators, you'll often chain several of them together. While working on such code, you might want to check out what's happening at various parts in the pipeline. To do that, insert a call to inspect().

It's more common for inspect() to be used as a debugging tool than to exist in your final code, but applications may find it useful in certain situations when errors need to be logged before being discarded.

Examples

Basic usage:

let a = [1, 4, 2, 3];

// this iterator sequence is complex.
let sum = a.iter()
    .cloned()
    .filter(|x| x % 2 == 0)
    .fold(0, |sum, i| sum + i);

println!("{}", sum);

// let's add some inspect() calls to investigate what's happening
let sum = a.iter()
    .cloned()
    .inspect(|x| println!("about to filter: {}", x))
    .filter(|x| x % 2 == 0)
    .inspect(|x| println!("made it through filter: {}", x))
    .fold(0, |sum, i| sum + i);

println!("{}", sum);

This will print:

6
about to filter: 1
about to filter: 4
made it through filter: 4
about to filter: 2
made it through filter: 2
about to filter: 3
6

Logging errors before discarding them:

let lines = ["1", "2", "a"];

let sum: i32 = lines
    .iter()
    .map(|line| line.parse::<i32>())
    .inspect(|num| {
        if let Err(ref e) = *num {
            println!("Parsing error: {}", e);
        }
    })
    .filter_map(Result::ok)
    .sum();

println!("Sum: {}", sum);

This will print:

Parsing error: invalid digit found in string
Sum: 3

Important traits for &'_ mut I

impl<'_, I> Iterator for &'_ mut I where
    I: Iterator + ?Sized,  type Item = <I as Iterator>::Item;

fn by_ref(&mut self) -> &mut Self

Borrows an iterator, rather than consuming it.

This is useful to allow applying iterator adaptors while still retaining ownership of the original iterator.

Examples

Basic usage:

let a = [1, 2, 3];

let iter = a.iter();

let sum: i32 = iter.take(5).fold(0, |acc, i| acc + i );

assert_eq!(sum, 6);

// if we try to use iter again, it won't work. The following line
// gives "error: use of moved value: `iter`
// assert_eq!(iter.next(), None);

// let's try that again
let a = [1, 2, 3];

let mut iter = a.iter();

// instead, we add in a .by_ref()
let sum: i32 = iter.by_ref().take(2).fold(0, |acc, i| acc + i );

assert_eq!(sum, 3);

// now this is just fine:
assert_eq!(iter.next(), Some(&3));
assert_eq!(iter.next(), None);

#[must_use = "if you really need to exhaust the iterator, consider `.for_each(drop)` instead"] fn collect<B>(self) -> B where
    B: FromIterator<Self::Item>, 

Transforms an iterator into a collection.

collect() can take anything iterable, and turn it into a relevant collection. This is one of the more powerful methods in the standard library, used in a variety of contexts.

The most basic pattern in which collect() is used is to turn one collection into another. You take a collection, call iter on it, do a bunch of transformations, and then collect() at the end.

One of the keys to collect()'s power is that many things you might not think of as 'collections' actually are. For example, a String is a collection of chars. And a collection of Result<T, E> can be thought of as single Result<Collection<T>, E>. See the examples below for more.

Because collect() is so general, it can cause problems with type inference. As such, collect() is one of the few times you'll see the syntax affectionately known as the 'turbofish': ::<>. This helps the inference algorithm understand specifically which collection you're trying to collect into.

Examples

Basic usage:

let a = [1, 2, 3];

let doubled: Vec<i32> = a.iter()
                         .map(|&x| x * 2)
                         .collect();

assert_eq!(vec![2, 4, 6], doubled);

Note that we needed the : Vec<i32> on the left-hand side. This is because we could collect into, for example, a VecDeque<T> instead:

use std::collections::VecDeque;

let a = [1, 2, 3];

let doubled: VecDeque<i32> = a.iter().map(|&x| x * 2).collect();

assert_eq!(2, doubled[0]);
assert_eq!(4, doubled[1]);
assert_eq!(6, doubled[2]);

Using the 'turbofish' instead of annotating doubled:

let a = [1, 2, 3];

let doubled = a.iter().map(|x| x * 2).collect::<Vec<i32>>();

assert_eq!(vec![2, 4, 6], doubled);

Because collect() only cares about what you're collecting into, you can still use a partial type hint, _, with the turbofish:

let a = [1, 2, 3];

let doubled = a.iter().map(|x| x * 2).collect::<Vec<_>>();

assert_eq!(vec![2, 4, 6], doubled);

Using collect() to make a String:

let chars = ['g', 'd', 'k', 'k', 'n'];

let hello: String = chars.iter()
    .map(|&x| x as u8)
    .map(|x| (x + 1) as char)
    .collect();

assert_eq!("hello", hello);

If you have a list of Result<T, E>s, you can use collect() to see if any of them failed:

let results = [Ok(1), Err("nope"), Ok(3), Err("bad")];

let result: Result<Vec<_>, &str> = results.iter().cloned().collect();

// gives us the first error
assert_eq!(Err("nope"), result);

let results = [Ok(1), Ok(3)];

let result: Result<Vec<_>, &str> = results.iter().cloned().collect();

// gives us the list of answers
assert_eq!(Ok(vec![1, 3]), result);

fn partition<B, F>(self, f: F) -> (B, B) where
    B: Default + Extend<Self::Item>,
    F: FnMut(&Self::Item) -> bool, 

Consumes an iterator, creating two collections from it.

The predicate passed to partition() can return true, or false. partition() returns a pair, all of the elements for which it returned true, and all of the elements for which it returned false.

See also is_partitioned() and partition_in_place().

Examples

Basic usage:

let a = [1, 2, 3];

let (even, odd): (Vec<i32>, Vec<i32>) = a
    .iter()
    .partition(|&n| n % 2 == 0);

assert_eq!(even, vec![2]);
assert_eq!(odd, vec![1, 3]);

fn partition_in_place<'a, T, P>(self, predicate: P) -> usize where
    P: FnMut(&T) -> bool,
    Self: DoubleEndedIterator<Item = &'a mut T>,
    T: 'a, 

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

new API

Reorders the elements of this iterator in-place according to the given predicate, such that all those that return true precede all those that return false. Returns the number of true elements found.

The relative order of partitioned items is not maintained.

See also is_partitioned() and partition().

Examples

#![feature(iter_partition_in_place)]

let mut a = [1, 2, 3, 4, 5, 6, 7];

// Partition in-place between evens and odds
let i = a.iter_mut().partition_in_place(|&n| n % 2 == 0);

assert_eq!(i, 3);
assert!(a[..i].iter().all(|&n| n % 2 == 0)); // evens
assert!(a[i..].iter().all(|&n| n % 2 == 1)); // odds

fn is_partitioned<P>(self, predicate: P) -> bool where
    P: FnMut(Self::Item) -> bool, 

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

new API

Checks if the elements of this iterator are partitioned according to the given predicate, such that all those that return true precede all those that return false.

See also partition() and partition_in_place().

Examples

#![feature(iter_is_partitioned)]

assert!("Iterator".chars().is_partitioned(char::is_uppercase));
assert!(!"IntoIterator".chars().is_partitioned(char::is_uppercase));

fn try_fold<B, F, R>(&mut self, init: B, f: F) -> R where
    F: FnMut(B, Self::Item) -> R,
    R: Try<Ok = B>, 

An iterator method that applies a function as long as it returns successfully, producing a single, final value.

try_fold() takes two arguments: an initial value, and a closure with two arguments: an 'accumulator', and an element. The closure either returns successfully, with the value that the accumulator should have for the next iteration, or it returns failure, with an error value that is propagated back to the caller immediately (short-circuiting).

The initial value is the value the accumulator will have on the first call. If applying the closure succeeded against every element of the iterator, try_fold() returns the final accumulator as success.

Folding is useful whenever you have a collection of something, and want to produce a single value from it.

Note to Implementors

Most of the other (forward) methods have default implementations in terms of this one, so try to implement this explicitly if it can do something better than the default for loop implementation.

In particular, try to have this call try_fold() on the internal parts from which this iterator is composed. If multiple calls are needed, the ? operator may be convenient for chaining the accumulator value along, but beware any invariants that need to be upheld before those early returns. This is a &mut self method, so iteration needs to be resumable after hitting an error here.

Examples

Basic usage:

let a = [1, 2, 3];

// the checked sum of all of the elements of the array
let sum = a.iter().try_fold(0i8, |acc, &x| acc.checked_add(x));

assert_eq!(sum, Some(6));

Short-circuiting:

let a = [10, 20, 30, 100, 40, 50];
let mut it = a.iter();

// This sum overflows when adding the 100 element
let sum = it.try_fold(0i8, |acc, &x| acc.checked_add(x));
assert_eq!(sum, None);

// Because it short-circuited, the remaining elements are still
// available through the iterator.
assert_eq!(it.len(), 2);
assert_eq!(it.next(), Some(&40));

fn try_for_each<F, R>(&mut self, f: F) -> R where
    F: FnMut(Self::Item) -> R,
    R: Try<Ok = ()>, 

An iterator method that applies a fallible function to each item in the iterator, stopping at the first error and returning that error.

This can also be thought of as the fallible form of for_each() or as the stateless version of try_fold().

Examples

use std::fs::rename;
use std::io::{stdout, Write};
use std::path::Path;

let data = ["no_tea.txt", "stale_bread.json", "torrential_rain.png"];

let res = data.iter().try_for_each(|x| writeln!(stdout(), "{}", x));
assert!(res.is_ok());

let mut it = data.iter().cloned();
let res = it.try_for_each(|x| rename(x, Path::new(x).with_extension("old")));
assert!(res.is_err());
// It short-circuited, so the remaining items are still in the iterator:
assert_eq!(it.next(), Some("stale_bread.json"));

fn fold<B, F>(self, init: B, f: F) -> B where
    F: FnMut(B, Self::Item) -> B, 

An iterator method that applies a function, producing a single, final value.

fold() takes two arguments: an initial value, and a closure with two arguments: an 'accumulator', and an element. The closure returns the value that the accumulator should have for the next iteration.

The initial value is the value the accumulator will have on the first call.

After applying this closure to every element of the iterator, fold() returns the accumulator.

This operation is sometimes called 'reduce' or 'inject'.

Folding is useful whenever you have a collection of something, and want to produce a single value from it.

Note: fold(), and similar methods that traverse the entire iterator, may not terminate for infinite iterators, even on traits for which a result is determinable in finite time.

Examples

Basic usage:

let a = [1, 2, 3];

// the sum of all of the elements of the array
let sum = a.iter().fold(0, |acc, x| acc + x);

assert_eq!(sum, 6);

Let's walk through each step of the iteration here:

element	acc	x	result
	0
1	0	1	1
2	1	2	3
3	3	3	6

And so, our final result, 6.

It's common for people who haven't used iterators a lot to use a for loop with a list of things to build up a result. Those can be turned into fold()s:

let numbers = [1, 2, 3, 4, 5];

let mut result = 0;

// for loop:
for i in &numbers {
    result = result + i;
}

// fold:
let result2 = numbers.iter().fold(0, |acc, &x| acc + x);

// they're the same
assert_eq!(result, result2);

fn all<F>(&mut self, f: F) -> bool where
    F: FnMut(Self::Item) -> bool, 

Tests if every element of the iterator matches a predicate.

all() takes a closure that returns true or false. It applies this closure to each element of the iterator, and if they all return true, then so does all(). If any of them return false, it returns false.

all() is short-circuiting; in other words, it will stop processing as soon as it finds a false, given that no matter what else happens, the result will also be false.

An empty iterator returns true.

Examples

Basic usage:

let a = [1, 2, 3];

assert!(a.iter().all(|&x| x > 0));

assert!(!a.iter().all(|&x| x > 2));

Stopping at the first false:

let a = [1, 2, 3];

let mut iter = a.iter();

assert!(!iter.all(|&x| x != 2));

// we can still use `iter`, as there are more elements.
assert_eq!(iter.next(), Some(&3));

fn any<F>(&mut self, f: F) -> bool where
    F: FnMut(Self::Item) -> bool, 

Tests if any element of the iterator matches a predicate.

any() takes a closure that returns true or false. It applies this closure to each element of the iterator, and if any of them return true, then so does any(). If they all return false, it returns false.

any() is short-circuiting; in other words, it will stop processing as soon as it finds a true, given that no matter what else happens, the result will also be true.

An empty iterator returns false.

Examples

Basic usage:

let a = [1, 2, 3];

assert!(a.iter().any(|&x| x > 0));

assert!(!a.iter().any(|&x| x > 5));

Stopping at the first true:

let a = [1, 2, 3];

let mut iter = a.iter();

assert!(iter.any(|&x| x != 2));

// we can still use `iter`, as there are more elements.
assert_eq!(iter.next(), Some(&2));

fn find<P>(&mut self, predicate: P) -> Option<Self::Item> where
    P: FnMut(&Self::Item) -> bool, 

Searches for an element of an iterator that satisfies a predicate.

find() takes a closure that returns true or false. It applies this closure to each element of the iterator, and if any of them return true, then find() returns Some(element). If they all return false, it returns None.

find() is short-circuiting; in other words, it will stop processing as soon as the closure returns true.

Because find() takes a reference, and many iterators iterate over references, this leads to a possibly confusing situation where the argument is a double reference. You can see this effect in the examples below, with &&x.

Examples

Basic usage:

let a = [1, 2, 3];

assert_eq!(a.iter().find(|&&x| x == 2), Some(&2));

assert_eq!(a.iter().find(|&&x| x == 5), None);

Stopping at the first true:

let a = [1, 2, 3];

let mut iter = a.iter();

assert_eq!(iter.find(|&&x| x == 2), Some(&2));

// we can still use `iter`, as there are more elements.
assert_eq!(iter.next(), Some(&3));

fn find_map<B, F>(&mut self, f: F) -> Option<B> where
    F: FnMut(Self::Item) -> Option<B>, 

Applies function to the elements of iterator and returns the first non-none result.

iter.find_map(f) is equivalent to iter.filter_map(f).next().

Examples

let a = ["lol", "NaN", "2", "5"];

let first_number = a.iter().find_map(|s| s.parse().ok());

assert_eq!(first_number, Some(2));

fn try_find<F, E, R>(&mut self, f: F) -> Result<Option<Self::Item>, E> where
    F: FnMut(&Self::Item) -> R,
    R: Try<Ok = bool, Error = E>, 

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

new API

Applies function to the elements of iterator and returns the first non-none result or the first error.

Examples

#![feature(try_find)]

let a = ["1", "2", "lol", "NaN", "5"];

let is_my_num = |s: &str, search: i32| -> Result<bool, std::num::ParseIntError> {
    Ok(s.parse::<i32>()?  == search)
};

let result = a.iter().try_find(|&&s| is_my_num(s, 2));
assert_eq!(result, Ok(Some(&"2")));

let result = a.iter().try_find(|&&s| is_my_num(s, 5));
assert!(result.is_err());

fn position<P>(&mut self, predicate: P) -> Option<usize> where
    P: FnMut(Self::Item) -> bool, 

Searches for an element in an iterator, returning its index.

position() takes a closure that returns true or false. It applies this closure to each element of the iterator, and if one of them returns true, then position() returns Some(index). If all of them return false, it returns None.

position() is short-circuiting; in other words, it will stop processing as soon as it finds a true.

Overflow Behavior

The method does no guarding against overflows, so if there are more than usize::MAX non-matching elements, it either produces the wrong result or panics. If debug assertions are enabled, a panic is guaranteed.

Panics

This function might panic if the iterator has more than usize::MAX non-matching elements.

Examples

Basic usage:

let a = [1, 2, 3];

assert_eq!(a.iter().position(|&x| x == 2), Some(1));

assert_eq!(a.iter().position(|&x| x == 5), None);

Stopping at the first true:

let a = [1, 2, 3, 4];

let mut iter = a.iter();

assert_eq!(iter.position(|&x| x >= 2), Some(1));

// we can still use `iter`, as there are more elements.
assert_eq!(iter.next(), Some(&3));

// The returned index depends on iterator state
assert_eq!(iter.position(|&x| x == 4), Some(0));

fn rposition<P>(&mut self, predicate: P) -> Option<usize> where
    P: FnMut(Self::Item) -> bool,
    Self: ExactSizeIterator + DoubleEndedIterator, 

Searches for an element in an iterator from the right, returning its index.

rposition() takes a closure that returns true or false. It applies this closure to each element of the iterator, starting from the end, and if one of them returns true, then rposition() returns Some(index). If all of them return false, it returns None.

rposition() is short-circuiting; in other words, it will stop processing as soon as it finds a true.

Examples

Basic usage:

let a = [1, 2, 3];

assert_eq!(a.iter().rposition(|&x| x == 3), Some(2));

assert_eq!(a.iter().rposition(|&x| x == 5), None);

Stopping at the first true:

let a = [1, 2, 3];

let mut iter = a.iter();

assert_eq!(iter.rposition(|&x| x == 2), Some(1));

// we can still use `iter`, as there are more elements.
assert_eq!(iter.next(), Some(&1));

fn max(self) -> Option<Self::Item> where
    Self::Item: Ord, 

Returns the maximum element of an iterator.

If several elements are equally maximum, the last element is returned. If the iterator is empty, None is returned.

Examples

Basic usage:

let a = [1, 2, 3];
let b: Vec<u32> = Vec::new();

assert_eq!(a.iter().max(), Some(&3));
assert_eq!(b.iter().max(), None);

fn min(self) -> Option<Self::Item> where
    Self::Item: Ord, 

Returns the minimum element of an iterator.

If several elements are equally minimum, the first element is returned. If the iterator is empty, None is returned.

Examples

Basic usage:

let a = [1, 2, 3];
let b: Vec<u32> = Vec::new();

assert_eq!(a.iter().min(), Some(&1));
assert_eq!(b.iter().min(), None);

fn max_by_key<B, F>(self, f: F) -> Option<Self::Item> where
    B: Ord,
    F: FnMut(&Self::Item) -> B, 

Returns the element that gives the maximum value from the specified function.

If several elements are equally maximum, the last element is returned. If the iterator is empty, None is returned.

Examples

let a = [-3_i32, 0, 1, 5, -10];
assert_eq!(*a.iter().max_by_key(|x| x.abs()).unwrap(), -10);

fn max_by<F>(self, compare: F) -> Option<Self::Item> where
    F: FnMut(&Self::Item, &Self::Item) -> Ordering, 

Returns the element that gives the maximum value with respect to the specified comparison function.

If several elements are equally maximum, the last element is returned. If the iterator is empty, None is returned.

Examples

let a = [-3_i32, 0, 1, 5, -10];
assert_eq!(*a.iter().max_by(|x, y| x.cmp(y)).unwrap(), 5);

fn min_by_key<B, F>(self, f: F) -> Option<Self::Item> where
    B: Ord,
    F: FnMut(&Self::Item) -> B, 

Returns the element that gives the minimum value from the specified function.

If several elements are equally minimum, the first element is returned. If the iterator is empty, None is returned.

Examples

let a = [-3_i32, 0, 1, 5, -10];
assert_eq!(*a.iter().min_by_key(|x| x.abs()).unwrap(), 0);

fn min_by<F>(self, compare: F) -> Option<Self::Item> where
    F: FnMut(&Self::Item, &Self::Item) -> Ordering, 

Returns the element that gives the minimum value with respect to the specified comparison function.

If several elements are equally minimum, the first element is returned. If the iterator is empty, None is returned.

Examples

let a = [-3_i32, 0, 1, 5, -10];
assert_eq!(*a.iter().min_by(|x, y| x.cmp(y)).unwrap(), -10);

Important traits for Rev<I>

impl<I> Iterator for Rev<I> where
    I: DoubleEndedIterator,  type Item = <I as Iterator>::Item;

fn rev(self) -> Rev<Self> where
    Self: DoubleEndedIterator, 

Reverses an iterator's direction.

Usually, iterators iterate from left to right. After using rev(), an iterator will instead iterate from right to left.

This is only possible if the iterator has an end, so rev() only works on DoubleEndedIterators.

Examples

let a = [1, 2, 3];

let mut iter = a.iter().rev();

assert_eq!(iter.next(), Some(&3));
assert_eq!(iter.next(), Some(&2));
assert_eq!(iter.next(), Some(&1));

assert_eq!(iter.next(), None);

fn unzip<A, B, FromA, FromB>(self) -> (FromA, FromB) where
    FromA: Default + Extend<A>,
    FromB: Default + Extend<B>,
    Self: Iterator<Item = (A, B)>, 

Converts an iterator of pairs into a pair of containers.

unzip() consumes an entire iterator of pairs, producing two collections: one from the left elements of the pairs, and one from the right elements.

This function is, in some sense, the opposite of zip.

Examples

Basic usage:

let a = [(1, 2), (3, 4)];

let (left, right): (Vec<_>, Vec<_>) = a.iter().cloned().unzip();

assert_eq!(left, [1, 3]);
assert_eq!(right, [2, 4]);

Important traits for Copied<I>

impl<'a, I, T> Iterator for Copied<I> where
    I: Iterator<Item = &'a T>,
    T: 'a + Copy,  type Item = T;

fn copied<'a, T>(self) -> Copied<Self> where
    Self: Iterator<Item = &'a T>,
    T: 'a + Copy, 

Creates an iterator which copies all of its elements.

This is useful when you have an iterator over &T, but you need an iterator over T.

Examples

Basic usage:

let a = [1, 2, 3];

let v_cloned: Vec<_> = a.iter().copied().collect();

// copied is the same as .map(|&x| x)
let v_map: Vec<_> = a.iter().map(|&x| x).collect();

assert_eq!(v_cloned, vec![1, 2, 3]);
assert_eq!(v_map, vec![1, 2, 3]);

Important traits for Cloned<I>

impl<'a, I, T> Iterator for Cloned<I> where
    I: Iterator<Item = &'a T>,
    T: 'a + Clone,  type Item = T;

fn cloned<'a, T>(self) -> Cloned<Self> where
    Self: Iterator<Item = &'a T>,
    T: 'a + Clone, 

Creates an iterator which clones all of its elements.

This is useful when you have an iterator over &T, but you need an iterator over T.

Examples

Basic usage:

let a = [1, 2, 3];

let v_cloned: Vec<_> = a.iter().cloned().collect();

// cloned is the same as .map(|&x| x), for integers
let v_map: Vec<_> = a.iter().map(|&x| x).collect();

assert_eq!(v_cloned, vec![1, 2, 3]);
assert_eq!(v_map, vec![1, 2, 3]);

Important traits for Cycle<I>

impl<I> Iterator for Cycle<I> where
    I: Clone + Iterator,  type Item = <I as Iterator>::Item;

fn cycle(self) -> Cycle<Self> where
    Self: Clone, 

Repeats an iterator endlessly.

Instead of stopping at None, the iterator will instead start again, from the beginning. After iterating again, it will start at the beginning again. And again. And again. Forever.

Examples

Basic usage:

let a = [1, 2, 3];

let mut it = a.iter().cycle();

assert_eq!(it.next(), Some(&1));
assert_eq!(it.next(), Some(&2));
assert_eq!(it.next(), Some(&3));
assert_eq!(it.next(), Some(&1));
assert_eq!(it.next(), Some(&2));
assert_eq!(it.next(), Some(&3));
assert_eq!(it.next(), Some(&1));

fn sum<S>(self) -> S where
    S: Sum<Self::Item>, 

Sums the elements of an iterator.

Takes each element, adds them together, and returns the result.

An empty iterator returns the zero value of the type.

Panics

When calling sum() and a primitive integer type is being returned, this method will panic if the computation overflows and debug assertions are enabled.

Examples

Basic usage:

let a = [1, 2, 3];
let sum: i32 = a.iter().sum();

assert_eq!(sum, 6);

fn product<P>(self) -> P where
    P: Product<Self::Item>, 

Iterates over the entire iterator, multiplying all the elements

An empty iterator returns the one value of the type.

Panics

When calling product() and a primitive integer type is being returned, method will panic if the computation overflows and debug assertions are enabled.

Examples

fn factorial(n: u32) -> u32 {
    (1..=n).product()
}
assert_eq!(factorial(0), 1);
assert_eq!(factorial(1), 1);
assert_eq!(factorial(5), 120);

fn cmp<I>(self, other: I) -> Ordering where
    I: IntoIterator<Item = Self::Item>,
    Self::Item: Ord, 

Lexicographically compares the elements of this Iterator with those of another.

Examples

use std::cmp::Ordering;

assert_eq!([1].iter().cmp([1].iter()), Ordering::Equal);
assert_eq!([1].iter().cmp([1, 2].iter()), Ordering::Less);
assert_eq!([1, 2].iter().cmp([1].iter()), Ordering::Greater);

fn cmp_by<I, F>(self, other: I, cmp: F) -> Ordering where
    F: FnMut(Self::Item, <I as IntoIterator>::Item) -> Ordering,
    I: IntoIterator, 

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

Lexicographically compares the elements of this Iterator with those of another with respect to the specified comparison function.

Examples

Basic usage:

#![feature(iter_order_by)]

use std::cmp::Ordering;

let xs = [1, 2, 3, 4];
let ys = [1, 4, 9, 16];

assert_eq!(xs.iter().cmp_by(&ys, |&x, &y| x.cmp(&y)), Ordering::Less);
assert_eq!(xs.iter().cmp_by(&ys, |&x, &y| (x * x).cmp(&y)), Ordering::Equal);
assert_eq!(xs.iter().cmp_by(&ys, |&x, &y| (2 * x).cmp(&y)), Ordering::Greater);

fn partial_cmp<I>(self, other: I) -> Option<Ordering> where
    I: IntoIterator,
    Self::Item: PartialOrd<<I as IntoIterator>::Item>, 

Lexicographically compares the elements of this Iterator with those of another.

Examples

use std::cmp::Ordering;

assert_eq!([1.].iter().partial_cmp([1.].iter()), Some(Ordering::Equal));
assert_eq!([1.].iter().partial_cmp([1., 2.].iter()), Some(Ordering::Less));
assert_eq!([1., 2.].iter().partial_cmp([1.].iter()), Some(Ordering::Greater));

assert_eq!([std::f64::NAN].iter().partial_cmp([1.].iter()), None);

fn partial_cmp_by<I, F>(self, other: I, partial_cmp: F) -> Option<Ordering> where
    F: FnMut(Self::Item, <I as IntoIterator>::Item) -> Option<Ordering>,
    I: IntoIterator, 

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

Lexicographically compares the elements of this Iterator with those of another with respect to the specified comparison function.

Examples

Basic usage:

#![feature(iter_order_by)]

use std::cmp::Ordering;

let xs = [1.0, 2.0, 3.0, 4.0];
let ys = [1.0, 4.0, 9.0, 16.0];

assert_eq!(
    xs.iter().partial_cmp_by(&ys, |&x, &y| x.partial_cmp(&y)),
    Some(Ordering::Less)
);
assert_eq!(
    xs.iter().partial_cmp_by(&ys, |&x, &y| (x * x).partial_cmp(&y)),
    Some(Ordering::Equal)
);
assert_eq!(
    xs.iter().partial_cmp_by(&ys, |&x, &y| (2.0 * x).partial_cmp(&y)),
    Some(Ordering::Greater)
);

fn eq<I>(self, other: I) -> bool where
    I: IntoIterator,
    Self::Item: PartialEq<<I as IntoIterator>::Item>, 

Determines if the elements of this Iterator are equal to those of another.

Examples

assert_eq!([1].iter().eq([1].iter()), true);
assert_eq!([1].iter().eq([1, 2].iter()), false);

fn eq_by<I, F>(self, other: I, eq: F) -> bool where
    F: FnMut(Self::Item, <I as IntoIterator>::Item) -> bool,
    I: IntoIterator, 

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

Determines if the elements of this Iterator are equal to those of another with respect to the specified equality function.

Examples

Basic usage:

#![feature(iter_order_by)]

let xs = [1, 2, 3, 4];
let ys = [1, 4, 9, 16];

assert!(xs.iter().eq_by(&ys, |&x, &y| x * x == y));

fn ne<I>(self, other: I) -> bool where
    I: IntoIterator,
    Self::Item: PartialEq<<I as IntoIterator>::Item>, 

Determines if the elements of this Iterator are unequal to those of another.

Examples

assert_eq!([1].iter().ne([1].iter()), false);
assert_eq!([1].iter().ne([1, 2].iter()), true);

fn lt<I>(self, other: I) -> bool where
    I: IntoIterator,
    Self::Item: PartialOrd<<I as IntoIterator>::Item>, 

Determines if the elements of this Iterator are lexicographically less than those of another.

Examples

assert_eq!([1].iter().lt([1].iter()), false);
assert_eq!([1].iter().lt([1, 2].iter()), true);
assert_eq!([1, 2].iter().lt([1].iter()), false);

fn le<I>(self, other: I) -> bool where
    I: IntoIterator,
    Self::Item: PartialOrd<<I as IntoIterator>::Item>, 

Determines if the elements of this Iterator are lexicographically less or equal to those of another.

Examples

assert_eq!([1].iter().le([1].iter()), true);
assert_eq!([1].iter().le([1, 2].iter()), true);
assert_eq!([1, 2].iter().le([1].iter()), false);

fn gt<I>(self, other: I) -> bool where
    I: IntoIterator,
    Self::Item: PartialOrd<<I as IntoIterator>::Item>, 

Determines if the elements of this Iterator are lexicographically greater than those of another.

Examples

assert_eq!([1].iter().gt([1].iter()), false);
assert_eq!([1].iter().gt([1, 2].iter()), false);
assert_eq!([1, 2].iter().gt([1].iter()), true);

fn ge<I>(self, other: I) -> bool where
    I: IntoIterator,
    Self::Item: PartialOrd<<I as IntoIterator>::Item>, 

Determines if the elements of this Iterator are lexicographically greater than or equal to those of another.

Examples

assert_eq!([1].iter().ge([1].iter()), true);
assert_eq!([1].iter().ge([1, 2].iter()), false);
assert_eq!([1, 2].iter().ge([1].iter()), true);

fn is_sorted(self) -> bool where
    Self::Item: PartialOrd<Self::Item>, 

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

new API

Checks if the elements of this iterator are sorted.

That is, for each element a and its following element b, a <= b must hold. If the iterator yields exactly zero or one element, true is returned.

Note that if Self::Item is only PartialOrd, but not Ord, the above definition implies that this function returns false if any two consecutive items are not comparable.

Examples

#![feature(is_sorted)]

assert!([1, 2, 2, 9].iter().is_sorted());
assert!(![1, 3, 2, 4].iter().is_sorted());
assert!([0].iter().is_sorted());
assert!(std::iter::empty::<i32>().is_sorted());
assert!(![0.0, 1.0, std::f32::NAN].iter().is_sorted());

fn is_sorted_by<F>(self, compare: F) -> bool where
    F: FnMut(&Self::Item, &Self::Item) -> Option<Ordering>, 

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

new API

Checks if the elements of this iterator are sorted using the given comparator function.

Instead of using PartialOrd::partial_cmp, this function uses the given compare function to determine the ordering of two elements. Apart from that, it's equivalent to is_sorted; see its documentation for more information.

Examples

#![feature(is_sorted)]

assert!([1, 2, 2, 9].iter().is_sorted_by(|a, b| a.partial_cmp(b)));
assert!(![1, 3, 2, 4].iter().is_sorted_by(|a, b| a.partial_cmp(b)));
assert!([0].iter().is_sorted_by(|a, b| a.partial_cmp(b)));
assert!(std::iter::empty::<i32>().is_sorted_by(|a, b| a.partial_cmp(b)));
assert!(![0.0, 1.0, std::f32::NAN].iter().is_sorted_by(|a, b| a.partial_cmp(b)));

fn is_sorted_by_key<F, K>(self, f: F) -> bool where
    F: FnMut(Self::Item) -> K,
    K: PartialOrd<K>, 

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

new API

Checks if the elements of this iterator are sorted using the given key extraction function.

Instead of comparing the iterator's elements directly, this function compares the keys of the elements, as determined by f. Apart from that, it's equivalent to is_sorted; see its documentation for more information.

Examples

#![feature(is_sorted)]

assert!(["c", "bb", "aaa"].iter().is_sorted_by_key(|s| s.len()));
assert!(![-2i32, -1, 0, 3].iter().is_sorted_by_key(|n| n.abs()));

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Implementations on Foreign Types

impl<T> Iterator for IntoIter<T>

type Item = T

fn next(&mut self) -> Option<T>

impl Iterator for Args

type Item = String

fn next(&mut self) -> Option<String>

fn size_hint(&self) -> (usize, Option<usize>)

impl<'a> Iterator for EncodeWide<'a>

type Item = u16

fn next(&mut self) -> Option<u16>

fn size_hint(&self) -> (usize, Option<usize>)

impl Iterator for VarsOs

type Item = (OsString, OsString)

fn next(&mut self) -> Option<(OsString, OsString)>

fn size_hint(&self) -> (usize, Option<usize>)

impl Iterator for ArgsOs

type Item = OsString

fn next(&mut self) -> Option<OsString>

fn size_hint(&self) -> (usize, Option<usize>)

impl<K> Iterator for IntoIter<K>

type Item = K

fn next(&mut self) -> Option<K>

fn size_hint(&self) -> (usize, Option<usize>)

impl<'a, T, S> Iterator for Union<'a, T, S> where
    S: BuildHasher,
    T: Eq + Hash, 

type Item = &'a T

fn next(&mut self) -> Option<&'a T>

fn size_hint(&self) -> (usize, Option<usize>)

impl<'a, K, V> Iterator for Keys<'a, K, V>

type Item = &'a K

fn next(&mut self) -> Option<&'a K>

fn size_hint(&self) -> (usize, Option<usize>)

impl<'a> Iterator for Components<'a>

type Item = Component<'a>

fn next(&mut self) -> Option<Component<'a>>

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

type Item = &'a K

fn next(&mut self) -> Option<&'a K>

fn size_hint(&self) -> (usize, Option<usize>)

impl<'a, K, V> Iterator for Iter<'a, K, V>

type Item = (&'a K, &'a V)

fn next(&mut self) -> Option<(&'a K, &'a V)>

fn size_hint(&self) -> (usize, Option<usize>)

impl<'a, K> Iterator for Drain<'a, K>

type Item = K

fn next(&mut self) -> Option<K>

fn size_hint(&self) -> (usize, Option<usize>)

impl Iterator for ReadDir

type Item = Result<DirEntry, Error>

fn next(&mut self) -> Option<Result<DirEntry, Error>>

impl<'a> Iterator for Chain<'a>

type Item = &'a (dyn Error + 'static)

fn next(&mut self) -> Option<<Chain<'a> as Iterator>::Item>

impl<'a, T> Iterator for TryIter<'a, T>

type Item = T

fn next(&mut self) -> Option<T>

impl<'a> Iterator for Incoming<'a>

type Item = Result<TcpStream, Error>

fn next(&mut self) -> Option<Result<TcpStream, Error>>

impl<'a, K, V> Iterator for IterMut<'a, K, V>

type Item = (&'a K, &'a mut V)

fn next(&mut self) -> Option<(&'a K, &'a mut V)>

fn size_hint(&self) -> (usize, Option<usize>)

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

type Item = (K, V)

fn next(&mut self) -> Option<(K, V)>

fn size_hint(&self) -> (usize, Option<usize>)

impl<B> Iterator for Split<B> where
    B: BufRead, 

type Item = Result<Vec<u8>, Error>

fn next(&mut self) -> Option<Result<Vec<u8>, Error>>

impl<'a, T, S> Iterator for Intersection<'a, T, S> where
    S: BuildHasher,
    T: Eq + Hash, 

type Item = &'a T

fn next(&mut self) -> Option<&'a T>

fn size_hint(&self) -> (usize, Option<usize>)

impl<'a> Iterator for SplitPaths<'a>

type Item = PathBuf

fn next(&mut self) -> Option<PathBuf>

fn size_hint(&self) -> (usize, Option<usize>)

impl<R> Iterator for Bytes<R> where
    R: Read, 

type Item = Result<u8, Error>

fn next(&mut self) -> Option<Result<u8, Error>>

impl<'a, K, V> Iterator for Values<'a, K, V>

type Item = &'a V

fn next(&mut self) -> Option<&'a V>

fn size_hint(&self) -> (usize, Option<usize>)

impl<'a, T> Iterator for Iter<'a, T>

type Item = T

fn next(&mut self) -> Option<T>

impl<'a> Iterator for Ancestors<'a>

type Item = &'a Path

fn next(&mut self) -> Option<<Ancestors<'a> as Iterator>::Item>

impl<'a, T, S> Iterator for SymmetricDifference<'a, T, S> where
    S: BuildHasher,
    T: Eq + Hash, 

type Item = &'a T

fn next(&mut self) -> Option<&'a T>

fn size_hint(&self) -> (usize, Option<usize>)

impl Iterator for Vars

type Item = (String, String)

fn next(&mut self) -> Option<(String, String)>

fn size_hint(&self) -> (usize, Option<usize>)

impl<B> Iterator for Lines<B> where
    B: BufRead, 

type Item = Result<String, Error>

fn next(&mut self) -> Option<Result<String, Error>>

impl<'a, T, S> Iterator for Difference<'a, T, S> where
    S: BuildHasher,
    T: Eq + Hash, 

type Item = &'a T

fn next(&mut self) -> Option<&'a T>

fn size_hint(&self) -> (usize, Option<usize>)

impl<'a, K, V> Iterator for ValuesMut<'a, K, V>

type Item = &'a mut V

fn next(&mut self) -> Option<&'a mut V>

fn size_hint(&self) -> (usize, Option<usize>)

impl<'a> Iterator for Iter<'a>

type Item = &'a OsStr

fn next(&mut self) -> Option<&'a OsStr>

impl<'a, K, V> Iterator for Drain<'a, K, V>

type Item = (K, V)

fn next(&mut self) -> Option<(K, V)>

fn size_hint(&self) -> (usize, Option<usize>)

impl<'a, T> Iterator for IterMut<'a, T>

type Item = &'a mut T

fn next(&mut self) -> Option<&'a mut T>

fn size_hint(&self) -> (usize, Option<usize>)

fn count(self) -> usize

fn nth(&mut self, n: usize) -> Option<&'a mut T>

fn last(self) -> Option<&'a mut T>

fn position<P>(&mut self, predicate: P) -> Option<usize> where
    P: FnMut(<IterMut<'a, T> as Iterator>::Item) -> bool,
    IterMut<'a, T>: Sized, 

fn rposition<P>(&mut self, predicate: P) -> Option<usize> where
    P: FnMut(<IterMut<'a, T> as Iterator>::Item) -> bool,
    IterMut<'a, T>: Sized,
    IterMut<'a, T>: ExactSizeIterator,
    IterMut<'a, T>: DoubleEndedIterator, 

impl<'_> Iterator for Bytes<'_>

type Item = u8

fn next(&mut self) -> Option<u8>

fn size_hint(&self) -> (usize, Option<usize>)

fn count(self) -> usize

fn last(self) -> Option<<Bytes<'_> as Iterator>::Item>

fn nth(&mut self, n: usize) -> Option<<Bytes<'_> as Iterator>::Item>

fn all<F>(&mut self, f: F) -> bool where
    F: FnMut(<Bytes<'_> as Iterator>::Item) -> bool, 

fn any<F>(&mut self, f: F) -> bool where
    F: FnMut(<Bytes<'_> as Iterator>::Item) -> bool, 

fn find<P>(&mut self, predicate: P) -> Option<<Bytes<'_> as Iterator>::Item> where
    P: FnMut(&<Bytes<'_> as Iterator>::Item) -> bool, 

fn position<P>(&mut self, predicate: P) -> Option<usize> where
    P: FnMut(<Bytes<'_> as Iterator>::Item) -> bool, 

fn rposition<P>(&mut self, predicate: P) -> Option<usize> where
    P: FnMut(<Bytes<'_> as Iterator>::Item) -> bool, 

impl<I> Iterator for Enumerate<I> where
    I: Iterator, 

type Item = (usize, <I as Iterator>::Item)

fn next(&mut self) -> Option<(usize, <I as Iterator>::Item)>

Overflow Behavior

The method does no guarding against overflows, so enumerating more than usize::MAX elements either produces the wrong result or panics. If debug assertions are enabled, a panic is guaranteed.

Panics

Might panic if the index of the element overflows a usize.

fn size_hint(&self) -> (usize, Option<usize>)

fn nth(&mut self, n: usize) -> Option<(usize, <I as Iterator>::Item)>

fn count(self) -> usize

fn try_fold<Acc, Fold, R>(&mut self, init: Acc, fold: Fold) -> R where
    Fold: FnMut(Acc, <Enumerate<I> as Iterator>::Item) -> R,
    R: Try<Ok = Acc>,
    Enumerate<I>: Sized, 

fn fold<Acc, Fold>(self, init: Acc, fold: Fold) -> Acc where
    Fold: FnMut(Acc, <Enumerate<I> as Iterator>::Item) -> Acc, 

impl Iterator for EscapeDebug

type Item = char

fn next(&mut self) -> Option<char>

fn size_hint(&self) -> (usize, Option<usize>)

impl<I> Iterator for Fuse<I> where
    I: Iterator, 

type Item = <I as Iterator>::Item

default fn next(&mut self) -> Option<<I as Iterator>::Item>

default fn nth(&mut self, n: usize) -> Option<<I as Iterator>::Item>

default fn last(self) -> Option<<I as Iterator>::Item>

default fn count(self) -> usize

default fn size_hint(&self) -> (usize, Option<usize>)

default fn try_fold<Acc, Fold, R>(&mut self, init: Acc, fold: Fold) -> R where
    Fold: FnMut(Acc, <Fuse<I> as Iterator>::Item) -> R,
    R: Try<Ok = Acc>,
    Fuse<I>: Sized, 

default fn fold<Acc, Fold>(self, init: Acc, fold: Fold) -> Acc where
    Fold: FnMut(Acc, <Fuse<I> as Iterator>::Item) -> Acc, 

impl Iterator for EscapeDefault

type Item = char

fn next(&mut self) -> Option<char>

fn size_hint(&self) -> (usize, Option<usize>)

fn count(self) -> usize

fn nth(&mut self, n: usize) -> Option<char>

fn last(self) -> Option<char>

impl<'a, P> Iterator for RSplitTerminator<'a, P> where
    P: Pattern<'a>,
    <P as Pattern<'a>>::Searcher: ReverseSearcher<'a>, 

type Item = &'a str

fn next(&mut self) -> Option<&'a str>

impl<'_, I> Iterator for &'_ mut I where
    I: Iterator + ?Sized, 

type Item = <I as Iterator>::Item

fn next(&mut self) -> Option<<I as Iterator>::Item>

fn size_hint(&self) -> (usize, Option<usize>)

fn nth(&mut self, n: usize) -> Option<<&'_ mut I as Iterator>::Item>

impl<'a> Iterator for LinesAny<'a>

type Item = &'a str

fn next(&mut self) -> Option<&'a str>

fn size_hint(&self) -> (usize, Option<usize>)

impl<'a> Iterator for Utf8LossyChunksIter<'a>

type Item = Utf8LossyChunk<'a>

fn next(&mut self) -> Option<Utf8LossyChunk<'a>>

impl<A, F> Iterator for OnceWith<F> where
    F: FnOnce() -> A, 

type Item = A

fn next(&mut self) -> Option<A>

fn size_hint(&self) -> (usize, Option<usize>)

impl<'a, T, P> Iterator for RSplit<'a, T, P> where
    P: FnMut(&T) -> bool, 

type Item = &'a [T]

fn next(&mut self) -> Option<&'a [T]>

fn size_hint(&self) -> (usize, Option<usize>)

impl<'a, P> Iterator for RSplit<'a, P> where
    P: Pattern<'a>,
    <P as Pattern<'a>>::Searcher: ReverseSearcher<'a>, 

type Item = &'a str

fn next(&mut self) -> Option<&'a str>

impl<T> Iterator for IntoIter<T>

type Item = T

fn next(&mut self) -> Option<T>

fn size_hint(&self) -> (usize, Option<usize>)

impl<'a> Iterator for Chars<'a>

type Item = char

fn next(&mut self) -> Option<char>

fn count(self) -> usize

fn size_hint(&self) -> (usize, Option<usize>)

fn last(self) -> Option<char>

impl<I, U> Iterator for Flatten<I> where
    I: Iterator,
    U: Iterator,
    <I as Iterator>::Item: IntoIterator,
    <<I as Iterator>::Item as IntoIterator>::IntoIter == U,
    <<I as Iterator>::Item as IntoIterator>::Item == <U as Iterator>::Item, 

type Item = <U as Iterator>::Item

fn next(&mut self) -> Option<<U as Iterator>::Item>

fn size_hint(&self) -> (usize, Option<usize>)

fn try_fold<Acc, Fold, R>(&mut self, init: Acc, fold: Fold) -> R where
    Fold: FnMut(Acc, <Flatten<I> as Iterator>::Item) -> R,
    R: Try<Ok = Acc>,
    Flatten<I>: Sized, 

fn fold<Acc, Fold>(self, init: Acc, fold: Fold) -> Acc where
    Fold: FnMut(Acc, <Flatten<I> as Iterator>::Item) -> Acc, 

impl<A> Iterator for Repeat<A> where
    A: Clone, 

type Item = A

fn next(&mut self) -> Option<A>

fn size_hint(&self) -> (usize, Option<usize>)

impl<T, F> Iterator for Successors<T, F> where
    F: FnMut(&T) -> Option<T>, 

type Item = T

fn next(&mut self) -> Option<<Successors<T, F> as Iterator>::Item>

fn size_hint(&self) -> (usize, Option<usize>)

impl<'a, P> Iterator for Split<'a, P> where
    P: Pattern<'a>, 

type Item = &'a str

fn next(&mut self) -> Option<&'a str>

impl<'a, T> Iterator for RChunksExact<'a, T>

type Item = &'a [T]

fn next(&mut self) -> Option<&'a [T]>

fn size_hint(&self) -> (usize, Option<usize>)

fn count(self) -> usize

fn nth(&mut self, n: usize) -> Option<<RChunksExact<'a, T> as Iterator>::Item>

fn last(self) -> Option<<RChunksExact<'a, T> as Iterator>::Item>

impl<'a, T, P> Iterator for RSplitN<'a, T, P> where
    P: FnMut(&T) -> bool, 

type Item = &'a [T]

fn next(&mut self) -> Option<&'a [T]>

fn size_hint(&self) -> (usize, Option<usize>)

impl<'a, T, P> Iterator for RSplitNMut<'a, T, P> where
    P: FnMut(&T) -> bool, 

type Item = &'a mut [T]

fn next(&mut self) -> Option<&'a mut [T]>

fn size_hint(&self) -> (usize, Option<usize>)

impl<I, P> Iterator for TakeWhile<I, P> where
    I: Iterator,
    P: FnMut(&<I as Iterator>::Item) -> bool, 

type Item = <I as Iterator>::Item

fn next(&mut self) -> Option<<I as Iterator>::Item>

fn size_hint(&self) -> (usize, Option<usize>)

fn try_fold<Acc, Fold, R>(&mut self, init: Acc, fold: Fold) -> R where
    Fold: FnMut(Acc, <TakeWhile<I, P> as Iterator>::Item) -> R,
    R: Try<Ok = Acc>,
    TakeWhile<I, P>: Sized, 

impl<A, F> Iterator for RepeatWith<F> where
    F: FnMut() -> A, 

type Item = A

fn next(&mut self) -> Option<A>

fn size_hint(&self) -> (usize, Option<usize>)

impl<'a, P> Iterator for SplitN<'a, P> where
    P: Pattern<'a>, 

type Item = &'a str

fn next(&mut self) -> Option<&'a str>

impl<'a, T> Iterator for ChunksExactMut<'a, T>

type Item = &'a mut [T]

fn next(&mut self) -> Option<&'a mut [T]>

fn size_hint(&self) -> (usize, Option<usize>)

fn count(self) -> usize

fn nth(&mut self, n: usize) -> Option<&'a mut [T]>

fn last(self) -> Option<<ChunksExactMut<'a, T> as Iterator>::Item>

impl<'a> Iterator for EncodeUtf16<'a>

type Item = u16

fn next(&mut self) -> Option<u16>

fn size_hint(&self) -> (usize, Option<usize>)

impl<A> Iterator for RangeFrom<A> where
    A: Step, 

type Item = A

fn next(&mut self) -> Option<A>

fn size_hint(&self) -> (usize, Option<usize>)

fn nth(&mut self, n: usize) -> Option<A>

impl<'a, A> Iterator for Iter<'a, A>

type Item = &'a A

fn next(&mut self) -> Option<&'a A>

fn size_hint(&self) -> (usize, Option<usize>)

impl<'a, T, P> Iterator for SplitMut<'a, T, P> where
    P: FnMut(&T) -> bool, 

type Item = &'a mut [T]

fn next(&mut self) -> Option<&'a mut [T]>

fn size_hint(&self) -> (usize, Option<usize>)

impl<'a, T> Iterator for RChunks<'a, T>

type Item = &'a [T]

fn next(&mut self) -> Option<&'a [T]>

fn size_hint(&self) -> (usize, Option<usize>)

fn count(self) -> usize

fn nth(&mut self, n: usize) -> Option<<RChunks<'a, T> as Iterator>::Item>

fn last(self) -> Option<<RChunks<'a, T> as Iterator>::Item>

impl<'a, T, P> Iterator for SplitInclusive<'a, T, P> where
    P: FnMut(&T) -> bool, 

type Item = &'a [T]

fn next(&mut self) -> Option<&'a [T]>

fn size_hint(&self) -> (usize, Option<usize>)

impl<I> Iterator for DecodeUtf16<I> where
    I: Iterator<Item = u16>, 

type Item = Result<char, DecodeUtf16Error>

fn next(&mut self) -> Option<Result<char, DecodeUtf16Error>>

fn size_hint(&self) -> (usize, Option<usize>)

impl<'a, P> Iterator for Matches<'a, P> where
    P: Pattern<'a>, 

type Item = &'a str

fn next(&mut self) -> Option<&'a str>

impl<A> Iterator for IntoIter<A>

type Item = A

fn next(&mut self) -> Option<A>

fn size_hint(&self) -> (usize, Option<usize>)

impl<I> Iterator for Rev<I> where
    I: DoubleEndedIterator, 

type Item = <I as Iterator>::Item

fn next(&mut self) -> Option<<I as Iterator>::Item>

fn size_hint(&self) -> (usize, Option<usize>)

fn nth(&mut self, n: usize) -> Option<<I as Iterator>::Item>

fn try_fold<B, F, R>(&mut self, init: B, f: F) -> R where
    F: FnMut(B, <Rev<I> as Iterator>::Item) -> R,
    R: Try<Ok = B>,
    Rev<I>: Sized, 

fn fold<Acc, F>(self, init: Acc, f: F) -> Acc where
    F: FnMut(Acc, <Rev<I> as Iterator>::Item) -> Acc, 

fn find<P>(&mut self, predicate: P) -> Option<<Rev<I> as Iterator>::Item> where
    P: FnMut(&<Rev<I> as Iterator>::Item) -> bool, 

impl<I, U, F> Iterator for FlatMap<I, U, F> where
    F: FnMut(<I as Iterator>::Item) -> U,
    I: Iterator,
    U: IntoIterator, 

type Item = <U as IntoIterator>::Item

fn next(&mut self) -> Option<<U as IntoIterator>::Item>

fn size_hint(&self) -> (usize, Option<usize>)

fn try_fold<Acc, Fold, R>(&mut self, init: Acc, fold: Fold) -> R where
    Fold: FnMut(Acc, <FlatMap<I, U, F> as Iterator>::Item) -> R,
    R: Try<Ok = Acc>,
    FlatMap<I, U, F>: Sized, 

fn fold<Acc, Fold>(self, init: Acc, fold: Fold) -> Acc where
    Fold: FnMut(Acc, <FlatMap<I, U, F> as Iterator>::Item) -> Acc, 

impl Iterator for EscapeUnicode

type Item = char

fn next(&mut self) -> Option<char>

fn size_hint(&self) -> (usize, Option<usize>)

fn count(self) -> usize

fn last(self) -> Option<char>

impl<'a, T> Iterator for RChunksExactMut<'a, T>

type Item = &'a mut [T]

fn next(&mut self) -> Option<&'a mut [T]>

fn size_hint(&self) -> (usize, Option<usize>)

fn count(self) -> usize

fn nth(&mut self, n: usize) -> Option<&'a mut [T]>

fn last(self) -> Option<<RChunksExactMut<'a, T> as Iterator>::Item>

impl<A, B> Iterator for Chain<A, B> where
    A: Iterator,
    B: Iterator<Item = <A as Iterator>::Item>, 

type Item = <A as Iterator>::Item

fn next(&mut self) -> Option<<A as Iterator>::Item>

fn count(self) -> usize

fn try_fold<Acc, F, R>(&mut self, init: Acc, f: F) -> R where
    F: FnMut(Acc, <Chain<A, B> as Iterator>::Item) -> R,
    R: Try<Ok = Acc>,
    Chain<A, B>: Sized, 

fn fold<Acc, F>(self, init: Acc, f: F) -> Acc where
    F: FnMut(Acc, <Chain<A, B> as Iterator>::Item) -> Acc, 

fn nth(&mut self, n: usize) -> Option<<A as Iterator>::Item>

fn find<P>(&mut self, predicate: P) -> Option<<Chain<A, B> as Iterator>::Item> where
    P: FnMut(&<Chain<A, B> as Iterator>::Item) -> bool, 

fn last(self) -> Option<<A as Iterator>::Item>

fn size_hint(&self) -> (usize, Option<usize>)

impl Iterator for EscapeDefault

type Item = u8

fn next(&mut self) -> Option<u8>

fn size_hint(&self) -> (usize, Option<usize>)

fn last(self) -> Option<u8>

impl<'a, P> Iterator for MatchIndices<'a, P> where
    P: Pattern<'a>, 

type Item = (usize, &'a str)

fn next(&mut self) -> Option<(usize, &'a str)>

impl<const N: usize, T> Iterator for IntoIter<T, N> where
    [T; N]: LengthAtMost32, 

type Item = T

fn next(&mut self) -> Option<<IntoIter<T, N> as Iterator>::Item>

fn size_hint(&self) -> (usize, Option<usize>)

fn count(self) -> usize

fn last(self) -> Option<<IntoIter<T, N> as Iterator>::Item>

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

type Item = B

fn next(&mut self) -> Option<B>

fn size_hint(&self) -> (usize, Option<usize>)

fn try_fold<Acc, G, R>(&mut self, init: Acc, g: G) -> R where
    G: FnMut(Acc, <Map<I, F> as Iterator>::Item) -> R,
    R: Try<Ok = Acc>,
    Map<I, F>: Sized, 

fn fold<Acc, G>(self, init: Acc, g: G) -> Acc where
    G: FnMut(Acc, <Map<I, F> as Iterator>::Item) -> Acc, 

impl<'a> Iterator for CharIndices<'a>

type Item = (usize, char)

fn next(&mut self) -> Option<(usize, char)>

fn count(self) -> usize

fn size_hint(&self) -> (usize, Option<usize>)

fn last(self) -> Option<(usize, char)>

impl<'a, I, T> Iterator for Copied<I> where
    I: Iterator<Item = &'a T>,
    T: 'a + Copy, 

type Item = T

fn next(&mut self) -> Option<T>

fn size_hint(&self) -> (usize, Option<usize>)

fn try_fold<B, F, R>(&mut self, init: B, f: F) -> R where
    F: FnMut(B, <Copied<I> as Iterator>::Item) -> R,
    R: Try<Ok = B>,
    Copied<I>: Sized, 

fn fold<Acc, F>(self, init: Acc, f: F) -> Acc where
    F: FnMut(Acc, <Copied<I> as Iterator>::Item) -> Acc, 

impl<'a, T> Iterator for Iter<'a, T>

type Item = &'a T

fn next(&mut self) -> Option<&'a T>

fn size_hint(&self) -> (usize, Option<usize>)

impl<A, B> Iterator for Zip<A, B> where
    A: Iterator,
    B: Iterator, 

type Item = (<A as Iterator>::Item, <B as Iterator>::Item)

fn next(&mut self) -> Option<<Zip<A, B> as Iterator>::Item>

fn size_hint(&self) -> (usize, Option<usize>)

fn nth(&mut self, n: usize) -> Option<<Zip<A, B> as Iterator>::Item>

impl<'a, T, P> Iterator for SplitInclusiveMut<'a, T, P> where
    P: FnMut(&T) -> bool, 

type Item = &'a mut [T]

fn next(&mut self) -> Option<&'a mut [T]>

fn size_hint(&self) -> (usize, Option<usize>)

impl<'a, T, P> Iterator for SplitNMut<'a, T, P> where
    P: FnMut(&T) -> bool, 

type Item = &'a mut [T]

fn next(&mut self) -> Option<&'a mut [T]>

fn size_hint(&self) -> (usize, Option<usize>)

impl<'a, T> Iterator for IterMut<'a, T>

type Item = &'a mut T

fn next(&mut self) -> Option<&'a mut T>

fn size_hint(&self) -> (usize, Option<usize>)

impl<T> Iterator for Once<T>

type Item = T

fn next(&mut self) -> Option<T>

fn size_hint(&self) -> (usize, Option<usize>)

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

type Item = <I as Iterator>::Item

fn next(&mut self) -> Option<<I as Iterator>::Item>

fn size_hint(&self) -> (usize, Option<usize>)

fn try_fold<Acc, Fold, R>(&mut self, init: Acc, fold: Fold) -> R where
    Fold: FnMut(Acc, <Inspect<I, F> as Iterator>::Item) -> R,
    R: Try<Ok = Acc>,
    Inspect<I, F>: Sized, 

fn fold<Acc, Fold>(self, init: Acc, fold: Fold) -> Acc where
    Fold: FnMut(Acc, <Inspect<I, F> as Iterator>::Item) -> Acc, 

impl<'a, T> Iterator for ChunksExact<'a, T>

type Item = &'a [T]

fn next(&mut self) -> Option<&'a [T]>

fn size_hint(&self) -> (usize, Option<usize>)

fn count(self) -> usize

fn nth(&mut self, n: usize) -> Option<<ChunksExact<'a, T> as Iterator>::Item>

fn last(self) -> Option<<ChunksExact<'a, T> as Iterator>::Item>

impl<B, I, St, F> Iterator for Scan<I, St, F> where
    F: FnMut(&mut St, <I as Iterator>::Item) -> Option<B>,
    I: Iterator, 

type Item = B

fn next(&mut self) -> Option<B>

fn size_hint(&self) -> (usize, Option<usize>)

fn try_fold<Acc, Fold, R>(&mut self, init: Acc, fold: Fold) -> R where
    Fold: FnMut(Acc, <Scan<I, St, F> as Iterator>::Item) -> R,
    R: Try<Ok = Acc>,
    Scan<I, St, F>: Sized, 

impl Iterator for ToUppercase

type Item = char

fn next(&mut self) -> Option<char>

fn size_hint(&self) -> (usize, Option<usize>)

impl<I> Iterator for StepBy<I> where
    I: Iterator, 

type Item = <I as Iterator>::Item

fn next(&mut self) -> Option<<StepBy<I> as Iterator>::Item>

fn size_hint(&self) -> (usize, Option<usize>)

fn nth(&mut self, n: usize) -> Option<<StepBy<I> as Iterator>::Item>

fn try_fold<Acc, F, R>(&mut self, acc: Acc, f: F) -> R where
    F: FnMut(Acc, <StepBy<I> as Iterator>::Item) -> R,
    R: Try<Ok = Acc>, 

impl<I> Iterator for Peekable<I> where
    I: Iterator, 

type Item = <I as Iterator>::Item

fn next(&mut self) -> Option<<I as Iterator>::Item>

fn count(self) -> usize

fn nth(&mut self, n: usize) -> Option<<I as Iterator>::Item>

fn last(self) -> Option<<I as Iterator>::Item>

fn size_hint(&self) -> (usize, Option<usize>)

fn try_fold<B, F, R>(&mut self, init: B, f: F) -> R where
    F: FnMut(B, <Peekable<I> as Iterator>::Item) -> R,
    R: Try<Ok = B>,
    Peekable<I>: Sized, 

fn fold<Acc, Fold>(self, init: Acc, fold: Fold) -> Acc where
    Fold: FnMut(Acc, <Peekable<I> as Iterator>::Item) -> Acc, 

impl Iterator for ToLowercase

type Item = char

fn next(&mut self) -> Option<char>

fn size_hint(&self) -> (usize, Option<usize>)

impl<'a, P> Iterator for RMatches<'a, P> where
    P: Pattern<'a>,
    <P as Pattern<'a>>::Searcher: ReverseSearcher<'a>, 

type Item = &'a str

fn next(&mut self) -> Option<&'a str>

impl<'a> Iterator for SplitAsciiWhitespace<'a>

type Item = &'a str

fn next(&mut self) -> Option<&'a str>

fn size_hint(&self) -> (usize, Option<usize>)

fn last(self) -> Option<&'a str>

impl<'a, T> Iterator for Windows<'a, T>

type Item = &'a [T]

fn next(&mut self) -> Option<&'a [T]>

fn size_hint(&self) -> (usize, Option<usize>)

fn count(self) -> usize

fn nth(&mut self, n: usize) -> Option<<Windows<'a, T> as Iterator>::Item>

fn last(self) -> Option<<Windows<'a, T> as Iterator>::Item>

impl<'a, P> Iterator for RMatchIndices<'a, P> where
    P: Pattern<'a>,
    <P as Pattern<'a>>::Searcher: ReverseSearcher<'a>, 

type Item = (usize, &'a str)

fn next(&mut self) -> Option<(usize, &'a str)>

impl<'a, T> Iterator for Iter<'a, T>

type Item = &'a T

fn next(&mut self) -> Option<&'a T>

fn size_hint(&self) -> (usize, Option<usize>)

fn count(self) -> usize

fn nth(&mut self, n: usize) -> Option<&'a T>

fn last(self) -> Option<&'a T>

fn position<P>(&mut self, predicate: P) -> Option<usize> where
    P: FnMut(<Iter<'a, T> as Iterator>::Item) -> bool,
    Iter<'a, T>: Sized, 

fn rposition<P>(&mut self, predicate: P) -> Option<usize> where
    P: FnMut(<Iter<'a, T> as Iterator>::Item) -> bool,
    Iter<'a, T>: Sized,
    Iter<'a, T>: ExactSizeIterator,
    Iter<'a, T>: DoubleEndedIterator, 

fn is_sorted_by<F>(self, compare: F) -> bool where
    F: FnMut(&<Iter<'a, T> as Iterator>::Item, &<Iter<'a, T> as Iterator>::Item) -> Option<Ordering>,
    Iter<'a, T>: Sized, 

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

new API

impl<'a, P> Iterator for RSplitN<'a, P> where
    P: Pattern<'a>,
    <P as Pattern<'a>>::Searcher: ReverseSearcher<'a>, 

type Item = &'a str

fn next(&mut self) -> Option<&'a str>

impl<I> Iterator for Cycle<I> where
    I: Clone + Iterator, 

type Item = <I as Iterator>::Item

fn next(&mut self) -> Option<<I as Iterator>::Item>

fn size_hint(&self) -> (usize, Option<usize>)

fn try_fold<Acc, F, R>(&mut self, acc: Acc, f: F) -> R where
    F: FnMut(Acc, <Cycle<I> as Iterator>::Item) -> R,
    R: Try<Ok = Acc>, 

impl<'a, T, P> Iterator for Split<'a, T, P> where
    P: FnMut(&T) -> bool, 

type Item = &'a [T]

fn next(&mut self) -> Option<&'a [T]>

fn size_hint(&self) -> (usize, Option<usize>)

impl<'a, T, P> Iterator for RSplitMut<'a, T, P> where
    P: FnMut(&T) -> bool, 

type Item = &'a mut [T]

fn next(&mut self) -> Option<&'a mut [T]>

fn size_hint(&self) -> (usize, Option<usize>)

impl<A> Iterator for Range<A> where
    A: Step, 

type Item = A

fn next(&mut self) -> Option<A>

fn size_hint(&self) -> (usize, Option<usize>)

fn nth(&mut self, n: usize) -> Option<A>

fn last(self) -> Option<A>

fn min(self) -> Option<A>

fn max(self) -> Option<A>

impl<I, P> Iterator for Filter<I, P> where
    I: Iterator,
    P: FnMut(&<I as Iterator>::Item) -> bool, 

type Item = <I as Iterator>::Item

fn next(&mut self) -> Option<<I as Iterator>::Item>

fn size_hint(&self) -> (usize, Option<usize>)

fn count(self) -> usize

fn try_fold<Acc, Fold, R>(&mut self, init: Acc, fold: Fold) -> R where
    Fold: FnMut(Acc, <Filter<I, P> as Iterator>::Item) -> R,
    R: Try<Ok = Acc>,
    Filter<I, P>: Sized, 

fn fold<Acc, Fold>(self, init: Acc, fold: Fold) -> Acc where
    Fold: FnMut(Acc, <Filter<I, P> as Iterator>::Item) -> Acc, 

impl<I, P> Iterator for SkipWhile<I, P> where
    I: Iterator,
    P: FnMut(&<I as Iterator>::Item) -> bool, 

type Item = <I as Iterator>::Item

fn next(&mut self) -> Option<<I as Iterator>::Item>

fn size_hint(&self) -> (usize, Option<usize>)

fn try_fold<Acc, Fold, R>(&mut self, init: Acc, fold: Fold) -> R where
    Fold: FnMut(Acc, <SkipWhile<I, P> as Iterator>::Item) -> R,
    R: Try<Ok = Acc>,
    SkipWhile<I, P>: Sized, 

fn fold<Acc, Fold>(self, init: Acc, fold: Fold) -> Acc where
    Fold: FnMut(Acc, <SkipWhile<I, P> as Iterator>::Item) -> Acc, 

impl<T, F> Iterator for FromFn<F> where
    F: FnMut() -> Option<T>, 

type Item = T

fn next(&mut self) -> Option<<FromFn<F> as Iterator>::Item>

impl<'a> Iterator for EscapeDebug<'a>

type Item = char

fn next(&mut self) -> Option<char>

fn size_hint(&self) -> (usize, Option<usize>)

fn try_fold<Acc, Fold, R>(&mut self, init: Acc, fold: Fold) -> R where
    Fold: FnMut(Acc, <EscapeDebug<'a> as Iterator>::Item) -> R,
    R: Try<Ok = Acc>,
    EscapeDebug<'a>: Sized, 

fn fold<Acc, Fold>(self, init: Acc, fold: Fold) -> Acc where
    Fold: FnMut(Acc, <EscapeDebug<'a> as Iterator>::Item) -> Acc, 

impl<'a, T> Iterator for Chunks<'a, T>

type Item = &'a [T]

fn next(&mut self) -> Option<&'a [T]>

fn size_hint(&self) -> (usize, Option<usize>)

fn count(self) -> usize

fn nth(&mut self, n: usize) -> Option<<Chunks<'a, T> as Iterator>::Item>

fn last(self) -> Option<<Chunks<'a, T> as Iterator>::Item>

impl<B, I, F> Iterator for FilterMap<I, F> where
    F: FnMut(<I as Iterator>::Item) -> Option<B>,
    I: Iterator, 

type Item = B

fn next(&mut self) -> Option<B>

fn size_hint(&self) -> (usize, Option<usize>)

fn try_fold<Acc, Fold, R>(&mut self, init: Acc, fold: Fold) -> R where
    Fold: FnMut(Acc, <FilterMap<I, F> as Iterator>::Item) -> R,
    R: Try<Ok = Acc>,
    FilterMap<I, F>: Sized, 

fn fold<Acc, Fold>(self, init: Acc, fold: Fold) -> Acc where
    Fold: FnMut(Acc, <FilterMap<I, F> as Iterator>::Item) -> Acc, 

impl<'a, I, T> Iterator for Cloned<I> where
    I: Iterator<Item = &'a T>,
    T: 'a + Clone, 

type Item = T

fn next(&mut self) -> Option<T>

fn size_hint(&self) -> (usize, Option<usize>)

fn try_fold<B, F, R>(&mut self, init: B, f: F) -> R where
    F: FnMut(B, <Cloned<I> as Iterator>::Item) -> R,
    R: Try<Ok = B>,
    Cloned<I>: Sized, 

fn fold<Acc, F>(self, init: Acc, f: F) -> Acc where
    F: FnMut(Acc, <Cloned<I> as Iterator>::Item) -> Acc, 

impl<'a, T> Iterator for ChunksMut<'a, T>

type Item = &'a mut [T]

fn next(&mut self) -> Option<&'a mut [T]>

fn size_hint(&self) -> (usize, Option<usize>)

fn count(self) -> usize

fn nth(&mut self, n: usize) -> Option<&'a mut [T]>

fn last(self) -> Option<<ChunksMut<'a, T> as Iterator>::Item>

impl<'a> Iterator for SplitWhitespace<'a>

type Item = &'a str

fn next(&mut self) -> Option<&'a str>

fn size_hint(&self) -> (usize, Option<usize>)

fn last(self) -> Option<&'a str>

impl<I> Iterator for Take<I> where
    I: Iterator, 

type Item = <I as Iterator>::Item

fn next(&mut self) -> Option<<I as Iterator>::Item>

fn nth(&mut self, n: usize) -> Option<<I as Iterator>::Item>

fn size_hint(&self) -> (usize, Option<usize>)

fn try_fold<Acc, Fold, R>(&mut self, init: Acc, fold: Fold) -> R where
    Fold: FnMut(Acc, <Take<I> as Iterator>::Item) -> R,
    R: Try<Ok = Acc>,
    Take<I>: Sized, 

impl<'a, P> Iterator for SplitInclusive<'a, P> where
    P: Pattern<'a>, 

type Item = &'a str

fn next(&mut self) -> Option<&'a str>

impl<'a, P> Iterator for SplitTerminator<'a, P> where
    P: Pattern<'a>, 

type Item = &'a str

fn next(&mut self) -> Option<&'a str>

impl<'a, T, P> Iterator for SplitN<'a, T, P> where
    P: FnMut(&T) -> bool, 

type Item = &'a [T]

fn next(&mut self) -> Option<&'a [T]>

fn size_hint(&self) -> (usize, Option<usize>)

impl<T> Iterator for Empty<T>

type Item = T

fn next(&mut self) -> Option<T>

fn size_hint(&self) -> (usize, Option<usize>)

impl<'a, T> Iterator for RChunksMut<'a, T>

type Item = &'a mut [T]

fn next(&mut self) -> Option<&'a mut [T]>

fn size_hint(&self) -> (usize, Option<usize>)

fn count(self) -> usize

fn nth(&mut self, n: usize) -> Option<&'a mut [T]>

fn last(self) -> Option<<RChunksMut<'a, T> as Iterator>::Item>

impl<A> Iterator for RangeInclusive<A> where
    A: Step, 

type Item = A

fn next(&mut self) -> Option<A>

fn size_hint(&self) -> (usize, Option<usize>)

fn nth(&mut self, n: usize) -> Option<A>

fn try_fold<B, F, R>(&mut self, init: B, f: F) -> R where
    F: FnMut(B, <RangeInclusive<A> as Iterator>::Item) -> R,
    R: Try<Ok = B>,
    RangeInclusive<A>: Sized, 

fn last(self) -> Option<A>

fn min(self) -> Option<A>

fn max(self) -> Option<A>

impl<'a> Iterator for Lines<'a>

type Item = &'a str

fn next(&mut self) -> Option<&'a str>

fn size_hint(&self) -> (usize, Option<usize>)

fn last(self) -> Option<&'a str>

impl<'a, A> Iterator for IterMut<'a, A>

type Item = &'a mut A

fn next(&mut self) -> Option<&'a mut A>

fn size_hint(&self) -> (usize, Option<usize>)

impl<'a> Iterator for EscapeUnicode<'a>

type Item = char

fn next(&mut self) -> Option<char>

fn size_hint(&self) -> (usize, Option<usize>)

fn try_fold<Acc, Fold, R>(&mut self, init: Acc, fold: Fold) -> R where
    Fold: FnMut(Acc, <EscapeUnicode<'a> as Iterator>::Item) -> R,
    R: Try<Ok = Acc>,
    EscapeUnicode<'a>: Sized, 

fn fold<Acc, Fold>(self, init: Acc, fold: Fold) -> Acc where
    Fold: FnMut(Acc, <EscapeUnicode<'a> as Iterator>::Item) -> Acc, 

impl<I> Iterator for Fuse<I> where
    I: FusedIterator, 

fn next(&mut self) -> Option<<I as Iterator>::Item>

fn nth(&mut self, n: usize) -> Option<<I as Iterator>::Item>

fn last(self) -> Option<<I as Iterator>::Item>

fn count(self) -> usize

fn size_hint(&self) -> (usize, Option<usize>)

fn try_fold<Acc, Fold, R>(&mut self, init: Acc, fold: Fold) -> R where
    Fold: FnMut(Acc, <Fuse<I> as Iterator>::Item) -> R,
    R: Try<Ok = Acc>,
    Fuse<I>: Sized, 

fn fold<Acc, Fold>(self, init: Acc, fold: Fold) -> Acc where
    Fold: FnMut(Acc, <Fuse<I> as Iterator>::Item) -> Acc, 

impl<'a> Iterator for EscapeDefault<'a>

type Item = char

fn next(&mut self) -> Option<char>

fn size_hint(&self) -> (usize, Option<usize>)

fn try_fold<Acc, Fold, R>(&mut self, init: Acc, fold: Fold) -> R where
    Fold: FnMut(Acc, <EscapeDefault<'a> as Iterator>::Item) -> R,
    R: Try<Ok = Acc>,
    EscapeDefault<'a>: Sized, 

fn fold<Acc, Fold>(self, init: Acc, fold: Fold) -> Acc where
    Fold: FnMut(Acc, <EscapeDefault<'a> as Iterator>::Item) -> Acc, 

impl<I> Iterator for Skip<I> where
    I: Iterator, 

type Item = <I as Iterator>::Item

fn next(&mut self) -> Option<<I as Iterator>::Item>

fn nth(&mut self, n: usize) -> Option<<I as Iterator>::Item>

fn count(self) -> usize

fn last(self) -> Option<<I as Iterator>::Item>

fn size_hint(&self) -> (usize, Option<usize>)

fn try_fold<Acc, Fold, R>(&mut self, init: Acc, fold: Fold) -> R where
    Fold: FnMut(Acc, <Skip<I> as Iterator>::Item) -> R,
    R: Try<Ok = Acc>,
    Skip<I>: Sized, 

fn fold<Acc, Fold>(self, init: Acc, fold: Fold) -> Acc where
    Fold: FnMut(Acc, <Skip<I> as Iterator>::Item) -> Acc, 

impl<B, I, P> Iterator for MapWhile<I, P> where
    I: Iterator,
    P: FnMut(<I as Iterator>::Item) -> Option<B>, 

type Item = B

fn next(&mut self) -> Option<B>

fn size_hint(&self) -> (usize, Option<usize>)

fn try_fold<Acc, Fold, R>(&mut self, init: Acc, fold: Fold) -> R where
    Fold: FnMut(Acc, <MapWhile<I, P> as Iterator>::Item) -> R,
    R: Try<Ok = Acc>,
    MapWhile<I, P>: Sized, 

impl<'_, T, F> Iterator for DrainFilter<'_, T, F> where
    F: FnMut(&mut T) -> bool, 

type Item = T

fn next(&mut self) -> Option<T>

fn size_hint(&self) -> (usize, Option<usize>)

impl<T> Iterator for IntoIter<T>

type Item = T

fn next(&mut self) -> Option<T>

fn size_hint(&self) -> (usize, Option<usize>)

impl<'_, T> Iterator for Drain<'_, T>

type Item = T

fn next(&mut self) -> Option<T>

fn size_hint(&self) -> (usize, Option<usize>)

impl<'a, T> Iterator for Iter<'a, T>

type Item = &'a T

fn next(&mut self) -> Option<&'a T>

fn size_hint(&self) -> (usize, Option<usize>)

fn last(self) -> Option<&'a T>

impl<'a, T> Iterator for Difference<'a, T> where
    T: Ord, 

type Item = &'a T

fn next(&mut self) -> Option<&'a T>

fn size_hint(&self) -> (usize, Option<usize>)

impl<'_, I> Iterator for Splice<'_, I> where
    I: Iterator, 

type Item = <I as Iterator>::Item

fn next(&mut self) -> Option<<Splice<'_, I> as Iterator>::Item>

fn size_hint(&self) -> (usize, Option<usize>)

impl<'a, T> Iterator for Iter<'a, T>

type Item = &'a T

fn next(&mut self) -> Option<&'a T>

fn size_hint(&self) -> (usize, Option<usize>)

fn last(self) -> Option<&'a T>

impl<'a, T> Iterator for Iter<'a, T>

type Item = &'a T

fn next(&mut self) -> Option<&'a T>

fn size_hint(&self) -> (usize, Option<usize>)

fn last(self) -> Option<&'a T>

impl<'_, T> Iterator for Drain<'_, T>

type Item = T

fn next(&mut self) -> Option<T>

fn size_hint(&self) -> (usize, Option<usize>)

impl<'_, T, F> Iterator for DrainFilter<'_, T, F> where
    F: FnMut(&mut T) -> bool, 

type Item = T

fn next(&mut self) -> Option<T>

fn size_hint(&self) -> (usize, Option<usize>)

impl<'_, T> Iterator for DrainSorted<'_, T> where
    T: Ord, 

type Item = T

fn next(&mut self) -> Option<T>

fn size_hint(&self) -> (usize, Option<usize>)

impl<'a, K, V> Iterator for RangeMut<'a, K, V>

type Item = (&'a K, &'a mut V)

fn next(&mut self) -> Option<(&'a K, &'a mut V)>

fn last(self) -> Option<(&'a K, &'a mut V)>

impl<'a, T> Iterator for Intersection<'a, T> where
    T: Ord, 

type Item = &'a T

fn next(&mut self) -> Option<&'a T>

fn size_hint(&self) -> (usize, Option<usize>)

impl<I> Iterator for Box<I> where
    I: Iterator + ?Sized, 

type Item = <I as Iterator>::Item

fn next(&mut self) -> Option<<I as Iterator>::Item>

fn size_hint(&self) -> (usize, Option<usize>)

fn nth(&mut self, n: usize) -> Option<<I as Iterator>::Item>

fn last(self) -> Option<<I as Iterator>::Item>

impl<'a, T> Iterator for Union<'a, T> where
    T: Ord, 

type Item = &'a T

fn next(&mut self) -> Option<&'a T>

fn size_hint(&self) -> (usize, Option<usize>)

impl<'_> Iterator for Drain<'_>

type Item = char

fn next(&mut self) -> Option<char>

fn size_hint(&self) -> (usize, Option<usize>)

fn last(self) -> Option<char>

impl<'a, T> Iterator for IterMut<'a, T>

type Item = &'a mut T

fn next(&mut self) -> Option<&'a mut T>

fn size_hint(&self) -> (usize, Option<usize>)

fn last(self) -> Option<&'a mut T>

impl<T> Iterator for IntoIter<T>

type Item = T

fn next(&mut self) -> Option<T>

fn size_hint(&self) -> (usize, Option<usize>)

fn count(self) -> usize

impl<'_, T> Iterator for Drain<'_, T>

type Item = T

fn next(&mut self) -> Option<T>

fn size_hint(&self) -> (usize, Option<usize>)

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

type Item = (K, V)

fn next(&mut self) -> Option<(K, V)>

fn size_hint(&self) -> (usize, Option<usize>)

impl<T> Iterator for IntoIterSorted<T> where
    T: Ord, 

type Item = T

fn next(&mut self) -> Option<T>

fn size_hint(&self) -> (usize, Option<usize>)

impl<'a, K, V> Iterator for IterMut<'a, K, V> where
    K: 'a,
    V: 'a, 

type Item = (&'a K, &'a mut V)

fn next(&mut self) -> Option<(&'a K, &'a mut V)>

fn size_hint(&self) -> (usize, Option<usize>)

fn last(self) -> Option<(&'a K, &'a mut V)>

impl<'a, K, V> Iterator for ValuesMut<'a, K, V>

type Item = &'a mut V

fn next(&mut self) -> Option<&'a mut V>

fn size_hint(&self) -> (usize, Option<usize>)

fn last(self) -> Option<&'a mut V>

impl<'a, K, V> Iterator for Values<'a, K, V>

type Item = &'a V

fn next(&mut self) -> Option<&'a V>

fn size_hint(&self) -> (usize, Option<usize>)

fn last(self) -> Option<&'a V>

impl<'a, T> Iterator for SymmetricDifference<'a, T> where
    T: Ord, 

type Item = &'a T

fn next(&mut self) -> Option<&'a T>

fn size_hint(&self) -> (usize, Option<usize>)

impl<'a, K, V> Iterator for Iter<'a, K, V> where
    K: 'a,
    V: 'a, 

type Item = (&'a K, &'a V)

fn next(&mut self) -> Option<(&'a K, &'a V)>

fn size_hint(&self) -> (usize, Option<usize>)

fn last(self) -> Option<(&'a K, &'a V)>

impl<T> Iterator for IntoIter<T>

type Item = T

fn next(&mut self) -> Option<T>

fn size_hint(&self) -> (usize, Option<usize>)

impl<'a, K, V> Iterator for Range<'a, K, V>

type Item = (&'a K, &'a V)

fn next(&mut self) -> Option<(&'a K, &'a V)>

fn last(self) -> Option<(&'a K, &'a V)>

impl<'a, T> Iterator for Iter<'a, T>

type Item = &'a T

fn next(&mut self) -> Option<&'a T>

fn size_hint(&self) -> (usize, Option<usize>)

fn fold<Acc, F>(self, accum: Acc, f: F) -> Acc where
    F: FnMut(Acc, <Iter<'a, T> as Iterator>::Item) -> Acc, 

fn try_fold<B, F, R>(&mut self, init: B, f: F) -> R where
    F: FnMut(B, <Iter<'a, T> as Iterator>::Item) -> R,
    R: Try<Ok = B>,
    Iter<'a, T>: Sized, 

fn nth(&mut self, n: usize) -> Option<<Iter<'a, T> as Iterator>::Item>

fn last(self) -> Option<&'a T>

impl<'a, K, V> Iterator for Keys<'a, K, V>

type Item = &'a K

fn next(&mut self) -> Option<&'a K>

fn size_hint(&self) -> (usize, Option<usize>)

fn last(self) -> Option<&'a K>

impl<T> Iterator for IntoIter<T>

type Item = T

fn next(&mut self) -> Option<T>

fn size_hint(&self) -> (usize, Option<usize>)

impl<'a, T> Iterator for Range<'a, T>

type Item = &'a T

fn next(&mut self) -> Option<&'a T>

fn last(self) -> Option<&'a T>

impl<'a, T> Iterator for IterMut<'a, T>

type Item = &'a mut T

fn next(&mut self) -> Option<&'a mut T>

fn size_hint(&self) -> (usize, Option<usize>)

fn fold<Acc, F>(self, accum: Acc, f: F) -> Acc where
    F: FnMut(Acc, <IterMut<'a, T> as Iterator>::Item) -> Acc, 

fn nth(&mut self, n: usize) -> Option<<IterMut<'a, T> as Iterator>::Item>

fn last(self) -> Option<&'a mut T>

impl<T> Iterator for IntoIter<T>

type Item = T

fn next(&mut self) -> Option<T>

fn size_hint(&self) -> (usize, Option<usize>)

impl<'a, K, V> Iterator for Keys<'a, K, V>

type Item = &'a K

fn next(&mut self) -> Option<&'a K>

fn size_hint(&self) -> (usize, Option<usize>)

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

type Item = &'a K

fn next(&mut self) -> Option<&'a K>

fn size_hint(&self) -> (usize, Option<usize>)

impl<'a, T, S> Iterator for SymmetricDifference<'a, T, S> where
    S: BuildHasher,
    T: Eq + Hash, 

type Item = &'a T

fn next(&mut self) -> Option<&'a T>

fn size_hint(&self) -> (usize, Option<usize>)

impl<'a, K, V> Iterator for Drain<'a, K, V>

type Item = (K, V)

fn next(&mut self) -> Option<(K, V)>

fn size_hint(&self) -> (usize, Option<usize>)

impl<K> Iterator for IntoIter<K>

type Item = K

fn next(&mut self) -> Option<K>

fn size_hint(&self) -> (usize, Option<usize>)

impl<'a, K, V> Iterator for IterMut<'a, K, V>

type Item = (&'a K, &'a mut V)

fn next(&mut self) -> Option<(&'a K, &'a mut V)>

fn size_hint(&self) -> (usize, Option<usize>)

impl<'a, T, S> Iterator for Intersection<'a, T, S> where
    S: BuildHasher,
    T: Eq + Hash, 

type Item = &'a T

fn next(&mut self) -> Option<&'a T>

fn size_hint(&self) -> (usize, Option<usize>)

impl<'a, T, S> Iterator for Difference<'a, T, S> where
    S: BuildHasher,
    T: Eq + Hash, 

type Item = &'a T

fn next(&mut self) -> Option<&'a T>

fn size_hint(&self) -> (usize, Option<usize>)

impl<'a, K, V> Iterator for Iter<'a, K, V>

type Item = (&'a K, &'a V)

fn next(&mut self) -> Option<(&'a K, &'a V)>

fn size_hint(&self) -> (usize, Option<usize>)

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

type Item = K

fn next(&mut self) -> Option<K>

fn size_hint(&self) -> (usize, Option<usize>)

impl<'a, K, V> Iterator for ValuesMut<'a, K, V>

type Item = &'a mut V

fn next(&mut self) -> Option<&'a mut V>

fn size_hint(&self) -> (usize, Option<usize>)

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

type Item = (K, V)

fn next(&mut self) -> Option<(K, V)>

fn size_hint(&self) -> (usize, Option<usize>)

impl<'a, K, V> Iterator for Values<'a, K, V>

type Item = &'a V

fn next(&mut self) -> Option<&'a V>

fn size_hint(&self) -> (usize, Option<usize>)

impl<'a, T, S> Iterator for Union<'a, T, S> where
    S: BuildHasher,
    T: Eq + Hash, 

type Item = &'a T

fn next(&mut self) -> Option<&'a T>

fn size_hint(&self) -> (usize, Option<usize>)

impl<T> Iterator for Parser<T> where
    T: Iterator<Item = char>, 

type Item = JsonEvent

fn next(&mut self) -> Option<JsonEvent>

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

type Item = <A as Array>::Item

fn next(&mut self) -> Option<<A as Array>::Item>

fn size_hint(&self) -> (usize, Option<usize>)

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

type Item = <T as Array>::Item

fn next(&mut self) -> Option<<T as Array>::Item>

fn size_hint(&self) -> (usize, Option<usize>)

impl<'a, T> Iterator for Drain<'a, T>

type Item = T

fn next(&mut self) -> Option<<Drain<'a, T> as Iterator>::Item>

fn size_hint(&self) -> (usize, Option<usize>)

fn count(self) -> usize

fn nth(&mut self, n: usize) -> Option<<Drain<'a, T> as Iterator>::Item>

fn last(self) -> Option<<Drain<'a, T> as Iterator>::Item>

fn collect<C>(self) -> C where
    C: FromIterator<<Drain<'a, T> as Iterator>::Item>, 

impl<'a, T, S1, S2> Iterator for SymmetricDifference<'a, T, S1, S2> where
    S1: BuildHasher,
    S2: BuildHasher,
    T: Eq + Hash, 

type Item = &'a T

fn next(
    &mut self
) -> Option<<SymmetricDifference<'a, T, S1, S2> as Iterator>::Item>

fn size_hint(&self) -> (usize, Option<usize>)

fn fold<B, F>(self, init: B, f: F) -> B where
    F: FnMut(B, <SymmetricDifference<'a, T, S1, S2> as Iterator>::Item) -> B, 

impl<'a, T> Iterator for Iter<'a, T>

type Item = &'a T

fn next(&mut self) -> Option<<Iter<'a, T> as Iterator>::Item>

fn size_hint(&self) -> (usize, Option<usize>)

fn count(self) -> usize

fn nth(&mut self, n: usize) -> Option<<Iter<'a, T> as Iterator>::Item>

fn last(self) -> Option<<Iter<'a, T> as Iterator>::Item>

fn collect<C>(self) -> C where
    C: FromIterator<<Iter<'a, T> as Iterator>::Item>, 

impl<'a, K, V> Iterator for Iter<'a, K, V>

type Item = (&'a K, &'a V)

fn next(&mut self) -> Option<<Iter<'a, K, V> as Iterator>::Item>

fn size_hint(&self) -> (usize, Option<usize>)

fn count(self) -> usize

fn nth(&mut self, n: usize) -> Option<<Iter<'a, K, V> as Iterator>::Item>

fn last(self) -> Option<<Iter<'a, K, V> as Iterator>::Item>

fn collect<C>(self) -> C where
    C: FromIterator<<Iter<'a, K, V> as Iterator>::Item>, 

impl<T> Iterator for IntoIter<T>

type Item = T

fn next(&mut self) -> Option<<IntoIter<T> as Iterator>::Item>

fn size_hint(&self) -> (usize, Option<usize>)

fn count(self) -> usize

fn nth(&mut self, n: usize) -> Option<<IntoIter<T> as Iterator>::Item>

fn last(self) -> Option<<IntoIter<T> as Iterator>::Item>

fn collect<C>(self) -> C where
    C: FromIterator<<IntoIter<T> as Iterator>::Item>, 

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

type Item = (K, V)

fn next(&mut self) -> Option<<IntoIter<K, V> as Iterator>::Item>

fn size_hint(&self) -> (usize, Option<usize>)

fn count(self) -> usize

fn nth(&mut self, n: usize) -> Option<<IntoIter<K, V> as Iterator>::Item>

fn last(self) -> Option<<IntoIter<K, V> as Iterator>::Item>

fn collect<C>(self) -> C where
    C: FromIterator<<IntoIter<K, V> as Iterator>::Item>, 

impl<'a, K, V> Iterator for IterMut<'a, K, V>

type Item = (&'a K, &'a mut V)

fn next(&mut self) -> Option<<IterMut<'a, K, V> as Iterator>::Item>

fn size_hint(&self) -> (usize, Option<usize>)

fn count(self) -> usize

fn nth(&mut self, n: usize) -> Option<<IterMut<'a, K, V> as Iterator>::Item>

fn last(self) -> Option<<IterMut<'a, K, V> as Iterator>::Item>

fn collect<C>(self) -> C where
    C: FromIterator<<IterMut<'a, K, V> as Iterator>::Item>, 

impl<'a, K, V> Iterator for Keys<'a, K, V>

type Item = &'a K

fn next(&mut self) -> Option<<Keys<'a, K, V> as Iterator>::Item>

fn size_hint(&self) -> (usize, Option<usize>)

fn count(self) -> usize

fn nth(&mut self, n: usize) -> Option<<Keys<'a, K, V> as Iterator>::Item>

fn last(self) -> Option<<Keys<'a, K, V> as Iterator>::Item>

fn collect<C>(self) -> C where
    C: FromIterator<<Keys<'a, K, V> as Iterator>::Item>, 

impl<'a, T, S> Iterator for Difference<'a, T, S> where
    S: BuildHasher,
    T: Eq + Hash, 

type Item = &'a T

fn next(&mut self) -> Option<<Difference<'a, T, S> as Iterator>::Item>

fn size_hint(&self) -> (usize, Option<usize>)

impl<'a, T, S> Iterator for Union<'a, T, S> where
    S: BuildHasher,
    T: Eq + Hash, 

type Item = &'a T

fn next(&mut self) -> Option<<Union<'a, T, S> as Iterator>::Item>

fn size_hint(&self) -> (usize, Option<usize>)

fn fold<B, F>(self, init: B, f: F) -> B where
    F: FnMut(B, <Union<'a, T, S> as Iterator>::Item) -> B, 

impl<'a, K, V> Iterator for Drain<'a, K, V>

type Item = (K, V)

fn next(&mut self) -> Option<<Drain<'a, K, V> as Iterator>::Item>

fn size_hint(&self) -> (usize, Option<usize>)

fn count(self) -> usize

fn nth(&mut self, n: usize) -> Option<<Drain<'a, K, V> as Iterator>::Item>

fn last(self) -> Option<<Drain<'a, K, V> as Iterator>::Item>

fn collect<C>(self) -> C where
    C: FromIterator<<Drain<'a, K, V> as Iterator>::Item>, 

impl<'a, K, V> Iterator for Values<'a, K, V>

type Item = &'a V

fn next(&mut self) -> Option<<Values<'a, K, V> as Iterator>::Item>

fn size_hint(&self) -> (usize, Option<usize>)

fn count(self) -> usize

fn nth(&mut self, n: usize) -> Option<<Values<'a, K, V> as Iterator>::Item>

fn last(self) -> Option<<Values<'a, K, V> as Iterator>::Item>

fn collect<C>(self) -> C where
    C: FromIterator<<Values<'a, K, V> as Iterator>::Item>, 

impl<'a, K, V> Iterator for ValuesMut<'a, K, V>

type Item = &'a mut V

fn next(&mut self) -> Option<<ValuesMut<'a, K, V> as Iterator>::Item>

fn size_hint(&self) -> (usize, Option<usize>)

fn count(self) -> usize

fn nth(&mut self, n: usize) -> Option<<ValuesMut<'a, K, V> as Iterator>::Item>

fn last(self) -> Option<<ValuesMut<'a, K, V> as Iterator>::Item>

fn collect<C>(self) -> C where
    C: FromIterator<<ValuesMut<'a, K, V> as Iterator>::Item>, 

impl<'a, T, S> Iterator for Intersection<'a, T, S> where
    S: BuildHasher,
    T: Eq + Hash, 

type Item = &'a T

fn next(&mut self) -> Option<<Intersection<'a, T, S> as Iterator>::Item>

fn size_hint(&self) -> (usize, Option<usize>)

impl<'a, T> Iterator for HybridIter<'a, T> where
    T: Idx, 

type Item = T

fn next(&mut self) -> Option<T>

impl<'a, T> Iterator for BitIter<'a, T> where
    T: Idx, 

type Item = T

fn next(&mut self) -> Option<T>

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

type Item = <A as Array>::Item

fn next(&mut self) -> Option<<A as Array>::Item>

fn size_hint(&self) -> (usize, Option<usize>)

impl<'a, T> Iterator for Drain<'a, T> where
    T: 'a, 

type Item = T

fn next(&mut self) -> Option<T>

fn size_hint(&self) -> (usize, Option<usize>)

impl<L, R> Iterator for Either<L, R> where
    L: Iterator,
    R: Iterator<Item = <L as Iterator>::Item>, 

Either<L, R> is an iterator if both L and R are iterators.

type Item = <L as Iterator>::Item

fn next(&mut self) -> Option<<Either<L, R> as Iterator>::Item>

fn size_hint(&self) -> (usize, Option<usize>)

fn fold<Acc, G>(self, init: Acc, f: G) -> Acc where
    G: FnMut(Acc, <Either<L, R> as Iterator>::Item) -> Acc, 

fn count(self) -> usize

fn last(self) -> Option<<Either<L, R> as Iterator>::Item>

fn nth(&mut self, n: usize) -> Option<<Either<L, R> as Iterator>::Item>

fn collect<B>(self) -> B where
    B: FromIterator<<Either<L, R> as Iterator>::Item>, 

fn all<F>(&mut self, f: F) -> bool where
    F: FnMut(<Either<L, R> as Iterator>::Item) -> bool, 

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Implementors

impl<'_, G: ?Sized> Iterator for DepthFirstSearch<'_, G> where
    G: DirectedGraph + WithNumNodes + WithSuccessors, 

type Item = G::Node

fn next(&mut self) -> Option<G::Node>

impl<'dom, Node: Idx> Iterator for rustc_ap_rustc_data_structures::graph::dominators::Iter<'dom, Node>

type Item = Node

fn next(&mut self) -> Option<Self::Item>

impl<'g, N: Debug, E: Debug> Iterator for AdjacentEdges<'g, N, E>

type Item = (EdgeIndex, &'g Edge<E>)

fn next(&mut self) -> Option<(EdgeIndex, &'g Edge<E>)>

fn size_hint(&self) -> (usize, Option<usize>)

impl<'g, N: Debug, E: Debug> Iterator for DepthFirstTraversal<'g, N, E>

type Item = NodeIndex

fn next(&mut self) -> Option<NodeIndex>

fn size_hint(&self) -> (usize, Option<usize>)

impl<Ls> Iterator for VecLinkedListIterator<Ls> where
    Ls: Links, 

type Item = Ls::LinkIndex

fn next(&mut self) -> Option<Ls::LinkIndex>

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