W3cubDocs

/Rust

Struct Peekable 

pub struct Peekable<I>where
    I: Iterator,{ /* private fields */ }

An iterator with a peek() that returns an optional reference to the next element.

This struct is created by the peekable method on Iterator. See its documentation for more.

Implementations

Source
impl<I> Peekable<I>where
    I: Iterator,
1.0.0Source
pub fn peek(&mut self) -> Option<&<I as Iterator>::Item>

Returns a reference to the next() value without advancing the iterator.

Like next, if there is a value, it is wrapped in a Some(T). But if the iteration is over, None is returned.

Because peek() returns a reference, and many iterators iterate over references, there can be a possibly confusing situation where the return value is a double reference. You can see this effect in the examples below.

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));

// The iterator does not advance even if we `peek` multiple times
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);
1.53.0Source
pub fn peek_mut(&mut self) -> Option<&mut <I as Iterator>::Item>

Returns a mutable reference to the next() value without advancing the iterator.

Like next, if there is a value, it is wrapped in a Some(T). But if the iteration is over, None is returned.

Because peek_mut() returns a reference, and many iterators iterate over references, there can be a possibly confusing situation where the return value is a double reference. You can see this effect in the examples below.

Examples

Basic usage:

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

// Like with `peek()`, we can see into the future without advancing the iterator.
assert_eq!(iter.peek_mut(), Some(&mut &1));
assert_eq!(iter.peek_mut(), Some(&mut &1));
assert_eq!(iter.next(), Some(&1));

// Peek into the iterator and set the value behind the mutable reference.
if let Some(p) = iter.peek_mut() {
    assert_eq!(*p, &2);
    *p = &5;
}

// The value we put in reappears as the iterator continues.
assert_eq!(iter.collect::<Vec<_>>(), vec![&5, &3]);
1.51.0Source
pub fn next_if(
    &mut self,
    func: impl FnOnce(&<I as Iterator>::Item) -> bool,
) -> Option<<I as Iterator>::Item>

Consume and return the next value of this iterator if a condition is true.

If func returns true for the next value of this iterator, consume and return it. Otherwise, return None.

Examples

Consume a number if it’s equal to 0.

let mut iter = (0..5).peekable();
// The first item of the iterator is 0; consume it.
assert_eq!(iter.next_if(|&x| x == 0), Some(0));
// The next item returned is now 1, so `next_if` will return `None`.
assert_eq!(iter.next_if(|&x| x == 0), None);
// `next_if` retains the next item if the predicate evaluates to `false` for it.
assert_eq!(iter.next(), Some(1));

Consume any number less than 10.

let mut iter = (1..20).peekable();
// Consume all numbers less than 10
while iter.next_if(|&x| x < 10).is_some() {}
// The next value returned will be 10
assert_eq!(iter.next(), Some(10));
1.51.0Source
pub fn next_if_eq<T>(&mut self, expected: &T) -> Option<<I as Iterator>::Item>where
    <I as Iterator>::Item: PartialEq<T>,
    T: ?Sized,

Consume and return the next item if it is equal to expected.

Example

Consume a number if it’s equal to 0.

let mut iter = (0..5).peekable();
// The first item of the iterator is 0; consume it.
assert_eq!(iter.next_if_eq(&0), Some(0));
// The next item returned is now 1, so `next_if_eq` will return `None`.
assert_eq!(iter.next_if_eq(&0), None);
// `next_if_eq` retains the next item if it was not equal to `expected`.
assert_eq!(iter.next(), Some(1));
Source
pub fn next_if_map<R>(
    &mut self,
    f: impl FnOnce(<I as Iterator>::Item) -> Result<R, <I as Iterator>::Item>,
) -> Option<R>
🔬This is a nightly-only experimental API. (peekable_next_if_map #143702)

Consumes the next value of this iterator and applies a function f on it, returning the result if the closure returns Ok.

Otherwise if the closure returns Err the value is put back for the next iteration.

The content of the Err variant is typically the original value of the closure, but this is not required. If a different value is returned, the next peek() or next() call will result in this new value. This is similar to modifying the output of peek_mut().

If the closure panics, the next value will always be consumed and dropped even if the panic is caught, because the closure never returned an Err value to put back.

See also: next_if_map_mut.

Examples

Parse the leading decimal number from an iterator of characters.

#![feature(peekable_next_if_map)]
let mut iter = "125 GOTO 10".chars().peekable();
let mut line_num = 0_u32;
while let Some(digit) = iter.next_if_map(|c| c.to_digit(10).ok_or(c)) {
    line_num = line_num * 10 + digit;
}
assert_eq!(line_num, 125);
assert_eq!(iter.collect::<String>(), " GOTO 10");

Matching custom types.

#![feature(peekable_next_if_map)]

#[derive(Debug, PartialEq, Eq)]
enum Node {
    Comment(String),
    Red(String),
    Green(String),
    Blue(String),
}

/// Combines all consecutive `Comment` nodes into a single one.
fn combine_comments(nodes: Vec<Node>) -> Vec<Node> {
    let mut result = Vec::with_capacity(nodes.len());
    let mut iter = nodes.into_iter().peekable();
    let mut comment_text = None::<String>;
    loop {
        // Typically the closure in .next_if_map() matches on the input,
        //  extracts the desired pattern into an `Ok`,
        //  and puts the rest into an `Err`.
        while let Some(text) = iter.next_if_map(|node| match node {
            Node::Comment(text) => Ok(text),
            other => Err(other),
        }) {
            comment_text.get_or_insert_default().push_str(&text);
        }

        if let Some(text) = comment_text.take() {
            result.push(Node::Comment(text));
        }
        if let Some(node) = iter.next() {
            result.push(node);
        } else {
            break;
        }
    }
    result
}
Source
pub fn next_if_map_mut<R>(
    &mut self,
    f: impl FnOnce(&mut <I as Iterator>::Item) -> Option<R>,
) -> Option<R>
🔬This is a nightly-only experimental API. (peekable_next_if_map #143702)

Gives a mutable reference to the next value of the iterator and applies a function f to it, returning the result and advancing the iterator if f returns Some.

Otherwise, if f returns None, the next value is kept for the next iteration.

If f panics, the item that is consumed from the iterator as if Some was returned from f. The value will be dropped.

This is similar to next_if_map, except ownership of the item is not given to f. This can be preferable if f would copy the item anyway.

Examples

Parse the leading decimal number from an iterator of characters.

#![feature(peekable_next_if_map)]
let mut iter = "125 GOTO 10".chars().peekable();
let mut line_num = 0_u32;
while let Some(digit) = iter.next_if_map_mut(|c| c.to_digit(10)) {
    line_num = line_num * 10 + digit;
}
assert_eq!(line_num, 125);
assert_eq!(iter.collect::<String>(), " GOTO 10");

Trait Implementations

1.0.0Source
impl<I> Clone for Peekable<I>where
    I: Clone + Iterator,
    <I as Iterator>::Item: Clone,
Source
fn clone(&self) -> Peekable<I> ⓘ
Returns a duplicate of the value. Read more
1.0.0Source
fn clone_from(&mut self, source: &Self)
Performs copy-assignment from source. Read more
1.0.0Source
impl<I> Debug for Peekable<I>where
    I: Debug + Iterator,
    <I as Iterator>::Item: Debug,
Source
fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>
Formats the value using the given formatter. Read more
1.38.0Source
impl<I> DoubleEndedIterator for Peekable<I>where
    I: DoubleEndedIterator,
Source
fn next_back(&mut self) -> Option<<Peekable<I> as Iterator>::Item>
Removes and returns an element from the end of the iterator. Read more
Source
fn try_rfold<B, F, R>(&mut self, init: B, f: F) -> Rwhere
    Peekable<I>: Sized,
    F: FnMut(B, <Peekable<I> as Iterator>::Item) -> R,
    R: Try<Output = B>,
This is the reverse version of Iterator::try_fold(): it takes elements starting from the back of the iterator. Read more
Source
fn rfold<Acc, Fold>(self, init: Acc, fold: Fold) -> Accwhere
    Fold: FnMut(Acc, <Peekable<I> as Iterator>::Item) -> Acc,
An iterator method that reduces the iterator’s elements to a single, final value, starting from the back. Read more
Source
fn advance_back_by(&mut self, n: usize) -> Result<(), NonZero<usize>>
🔬This is a nightly-only experimental API. (iter_advance_by #77404)
Advances the iterator from the back by n elements. Read more
1.37.0Source
fn nth_back(&mut self, n: usize) -> Option<Self::Item>
Returns the nth element from the end of the iterator. Read more
1.27.0Source
fn rfind<P>(&mut self, predicate: P) -> Option<Self::Item>where
    Self: Sized,
    P: FnMut(&Self::Item) -> bool,
Searches for an element of an iterator from the back that satisfies a predicate. Read more
1.0.0Source
impl<I> ExactSizeIterator for Peekable<I>where
    I: ExactSizeIterator,
1.0.0Source
fn len(&self) -> usize
Returns the exact remaining length of the iterator. Read more
Source
fn is_empty(&self) -> bool
🔬This is a nightly-only experimental API. (exact_size_is_empty #35428)
Returns true if the iterator is empty. Read more
1.0.0Source
impl<I> Iterator for Peekable<I>where
    I: Iterator,
Source
type Item = <I as Iterator>::Item
The type of the elements being iterated over.
Source
fn next(&mut self) -> Option<<I as Iterator>::Item>
Advances the iterator and returns the next value. Read more
Source
fn count(self) -> usize
Consumes the iterator, counting the number of iterations and returning it. Read more
Source
fn nth(&mut self, n: usize) -> Option<<I as Iterator>::Item>
Returns the nth element of the iterator. Read more
Source
fn last(self) -> Option<<I as Iterator>::Item>
Consumes the iterator, returning the last element. Read more
Source
fn size_hint(&self) -> (usize, Option<usize>)
Returns the bounds on the remaining length of the iterator. Read more
Source
fn try_fold<B, F, R>(&mut self, init: B, f: F) -> Rwhere
    Peekable<I>: Sized,
    F: FnMut(B, <Peekable<I> as Iterator>::Item) -> R,
    R: Try<Output = B>,
An iterator method that applies a function as long as it returns successfully, producing a single, final value. Read more
Source
fn fold<Acc, Fold>(self, init: Acc, fold: Fold) -> Accwhere
    Fold: FnMut(Acc, <Peekable<I> as Iterator>::Item) -> Acc,
Folds every element into an accumulator by applying an operation, returning the final result. Read more
Source
fn next_chunk<const N: usize>(
    &mut self,
) -> Result<[Self::Item; N], IntoIter<Self::Item, N>>where
    Self: Sized,
🔬This is a nightly-only experimental API. (iter_next_chunk #98326)
Advances the iterator and returns an array containing the next N values. Read more
Source
fn advance_by(&mut self, n: usize) -> Result<(), NonZero<usize>>
🔬This is a nightly-only experimental API. (iter_advance_by #77404)
Advances the iterator by n elements. Read more
1.28.0Source
fn step_by(self, step: usize) -> StepBy<Self> ⓘwhere
    Self: Sized,
Creates an iterator starting at the same point, but stepping by the given amount at each iteration. Read more
1.0.0Source
fn chain<U>(self, other: U) -> Chain<Self, <U as IntoIterator>::IntoIter> ⓘwhere
    Self: Sized,
    U: IntoIterator<Item = Self::Item>,
Takes two iterators and creates a new iterator over both in sequence. Read more
1.0.0Source
fn zip<U>(self, other: U) -> Zip<Self, <U as IntoIterator>::IntoIter> ⓘwhere
    Self: Sized,
    U: IntoIterator,
‘Zips up’ two iterators into a single iterator of pairs. Read more
Source
fn intersperse(self, separator: Self::Item) -> Intersperse<Self> ⓘwhere
    Self: Sized,
    Self::Item: Clone,
🔬This is a nightly-only experimental API. (iter_intersperse #79524)
Creates a new iterator which places a copy of separator between adjacent items of the original iterator. Read more
Source
fn intersperse_with<G>(self, separator: G) -> IntersperseWith<Self, G> ⓘwhere
    Self: Sized,
    G: FnMut() -> Self::Item,
🔬This is a nightly-only experimental API. (iter_intersperse #79524)
Creates a new iterator which places an item generated by separator between adjacent items of the original iterator. Read more
1.0.0Source
fn map<B, F>(self, f: F) -> Map<Self, F> ⓘwhere
    Self: Sized,
    F: FnMut(Self::Item) -> B,
Takes a closure and creates an iterator which calls that closure on each element. Read more
1.21.0Source
fn for_each<F>(self, f: F)where
    Self: Sized,
    F: FnMut(Self::Item),
Calls a closure on each element of an iterator. Read more
1.0.0Source
fn filter<P>(self, predicate: P) -> Filter<Self, P> ⓘwhere
    Self: Sized,
    P: FnMut(&Self::Item) -> bool,
Creates an iterator which uses a closure to determine if an element should be yielded. Read more
1.0.0Source
fn filter_map<B, F>(self, f: F) -> FilterMap<Self, F> ⓘwhere
    Self: Sized,
    F: FnMut(Self::Item) -> Option<B>,
Creates an iterator that both filters and maps. Read more
1.0.0Source
fn enumerate(self) -> Enumerate<Self> ⓘwhere
    Self: Sized,
Creates an iterator which gives the current iteration count as well as the next value. Read more
1.0.0Source
fn peekable(self) -> Peekable<Self> ⓘwhere
    Self: Sized,
Creates an iterator which can use the peek and peek_mut methods to look at the next element of the iterator without consuming it. See their documentation for more information. Read more
1.0.0Source
fn skip_while<P>(self, predicate: P) -> SkipWhile<Self, P> ⓘwhere
    Self: Sized,
    P: FnMut(&Self::Item) -> bool,
Creates an iterator that skips elements based on a predicate. Read more
1.0.0Source
fn take_while<P>(self, predicate: P) -> TakeWhile<Self, P> ⓘwhere
    Self: Sized,
    P: FnMut(&Self::Item) -> bool,
Creates an iterator that yields elements based on a predicate. Read more
1.57.0Source
fn map_while<B, P>(self, predicate: P) -> MapWhile<Self, P> ⓘwhere
    Self: Sized,
    P: FnMut(Self::Item) -> Option<B>,
Creates an iterator that both yields elements based on a predicate and maps. Read more
1.0.0Source
fn skip(self, n: usize) -> Skip<Self> ⓘwhere
    Self: Sized,
Creates an iterator that skips the first n elements. Read more
1.0.0Source
fn take(self, n: usize) -> Take<Self> ⓘwhere
    Self: Sized,
Creates an iterator that yields the first n elements, or fewer if the underlying iterator ends sooner. Read more
1.0.0Source
fn scan<St, B, F>(self, initial_state: St, f: F) -> Scan<Self, St, F> ⓘwhere
    Self: Sized,
    F: FnMut(&mut St, Self::Item) -> Option<B>,
An iterator adapter which, like fold, holds internal state, but unlike fold, produces a new iterator. Read more
1.0.0Source
fn flat_map<U, F>(self, f: F) -> FlatMap<Self, U, F> ⓘwhere
    Self: Sized,
    U: IntoIterator,
    F: FnMut(Self::Item) -> U,
Creates an iterator that works like map, but flattens nested structure. Read more
1.29.0Source
fn flatten(self) -> Flatten<Self> ⓘwhere
    Self: Sized,
    Self::Item: IntoIterator,
Creates an iterator that flattens nested structure. Read more
Source
fn map_windows<F, R, const N: usize>(self, f: F) -> MapWindows<Self, F, N> ⓘwhere
    Self: Sized,
    F: FnMut(&[Self::Item; N]) -> R,
🔬This is a nightly-only experimental API. (iter_map_windows #87155)
Calls the given function f for each contiguous window of size N over self and returns an iterator over the outputs of f. Like slice::windows(), the windows during mapping overlap as well. Read more
1.0.0Source
fn fuse(self) -> Fuse<Self> ⓘwhere
    Self: Sized,
Creates an iterator which ends after the first None. Read more
1.0.0Source
fn inspect<F>(self, f: F) -> Inspect<Self, F> ⓘwhere
    Self: Sized,
    F: FnMut(&Self::Item),
Does something with each element of an iterator, passing the value on. Read more
1.0.0Source
fn by_ref(&mut self) -> &mut Selfwhere
    Self: Sized,
Creates a “by reference” adapter for this instance of Iterator. Read more
1.0.0Source
fn collect<B>(self) -> Bwhere
    B: FromIterator<Self::Item>,
    Self: Sized,
Transforms an iterator into a collection. Read more
Source
fn try_collect<B>(
    &mut self,
) -> <<Self::Item as Try>::Residual as Residual<B>>::TryTypewhere
    Self: Sized,
    Self::Item: Try,
    <Self::Item as Try>::Residual: Residual<B>,
    B: FromIterator<<Self::Item as Try>::Output>,
🔬This is a nightly-only experimental API. (iterator_try_collect #94047)
Fallibly transforms an iterator into a collection, short circuiting if a failure is encountered. Read more
Source
fn collect_into<E>(self, collection: &mut E) -> &mut Ewhere
    E: Extend<Self::Item>,
    Self: Sized,
🔬This is a nightly-only experimental API. (iter_collect_into #94780)
Collects all the items from an iterator into a collection. Read more
1.0.0Source
fn partition<B, F>(self, f: F) -> (B, B)where
    Self: Sized,
    B: Default + Extend<Self::Item>,
    F: FnMut(&Self::Item) -> bool,
Consumes an iterator, creating two collections from it. Read more
Source
fn partition_in_place<'a, T, P>(self, predicate: P) -> usizewhere
    T: 'a,
    Self: Sized + DoubleEndedIterator<Item = &'a mut T>,
    P: FnMut(&T) -> bool,
🔬This is a nightly-only experimental API. (iter_partition_in_place #62543)
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. Read more
Source
fn is_partitioned<P>(self, predicate: P) -> boolwhere
    Self: Sized,
    P: FnMut(Self::Item) -> bool,
🔬This is a nightly-only experimental API. (iter_is_partitioned #62544)
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. Read more
1.27.0Source
fn try_for_each<F, R>(&mut self, f: F) -> Rwhere
    Self: Sized,
    F: FnMut(Self::Item) -> R,
    R: Try<Output = ()>,
An iterator method that applies a fallible function to each item in the iterator, stopping at the first error and returning that error. Read more
1.51.0Source
fn reduce<F>(self, f: F) -> Option<Self::Item>where
    Self: Sized,
    F: FnMut(Self::Item, Self::Item) -> Self::Item,
Reduces the elements to a single one, by repeatedly applying a reducing operation. Read more
Source
fn try_reduce<R>(
    &mut self,
    f: impl FnMut(Self::Item, Self::Item) -> R,
) -> <<R as Try>::Residual as Residual<Option<<R as Try>::Output>>>::TryTypewhere
    Self: Sized,
    R: Try<Output = Self::Item>,
    <R as Try>::Residual: Residual<Option<Self::Item>>,
🔬This is a nightly-only experimental API. (iterator_try_reduce #87053)
Reduces the elements to a single one by repeatedly applying a reducing operation. If the closure returns a failure, the failure is propagated back to the caller immediately. Read more
1.0.0Source
fn all<F>(&mut self, f: F) -> boolwhere
    Self: Sized,
    F: FnMut(Self::Item) -> bool,
Tests if every element of the iterator matches a predicate. Read more
1.0.0Source
fn any<F>(&mut self, f: F) -> boolwhere
    Self: Sized,
    F: FnMut(Self::Item) -> bool,
Tests if any element of the iterator matches a predicate. Read more
1.0.0Source
fn find<P>(&mut self, predicate: P) -> Option<Self::Item>where
    Self: Sized,
    P: FnMut(&Self::Item) -> bool,
Searches for an element of an iterator that satisfies a predicate. Read more
1.30.0Source
fn find_map<B, F>(&mut self, f: F) -> Option<B>where
    Self: Sized,
    F: FnMut(Self::Item) -> Option<B>,
Applies function to the elements of iterator and returns the first non-none result. Read more
Source
fn try_find<R>(
    &mut self,
    f: impl FnMut(&Self::Item) -> R,
) -> <<R as Try>::Residual as Residual<Option<Self::Item>>>::TryTypewhere
    Self: Sized,
    R: Try<Output = bool>,
    <R as Try>::Residual: Residual<Option<Self::Item>>,
🔬This is a nightly-only experimental API. (try_find #63178)
Applies function to the elements of iterator and returns the first true result or the first error. Read more
1.0.0Source
fn position<P>(&mut self, predicate: P) -> Option<usize>where
    Self: Sized,
    P: FnMut(Self::Item) -> bool,
Searches for an element in an iterator, returning its index. Read more
1.0.0Source
fn rposition<P>(&mut self, predicate: P) -> Option<usize>where
    P: FnMut(Self::Item) -> bool,
    Self: Sized + ExactSizeIterator + DoubleEndedIterator,
Searches for an element in an iterator from the right, returning its index. Read more
1.0.0Source
fn max(self) -> Option<Self::Item>where
    Self: Sized,
    Self::Item: Ord,
Returns the maximum element of an iterator. Read more
1.0.0Source
fn min(self) -> Option<Self::Item>where
    Self: Sized,
    Self::Item: Ord,
Returns the minimum element of an iterator. Read more
1.6.0Source
fn max_by_key<B, F>(self, f: F) -> Option<Self::Item>where
    B: Ord,
    Self: Sized,
    F: FnMut(&Self::Item) -> B,
Returns the element that gives the maximum value from the specified function. Read more
1.15.0Source
fn max_by<F>(self, compare: F) -> Option<Self::Item>where
    Self: Sized,
    F: FnMut(&Self::Item, &Self::Item) -> Ordering,
Returns the element that gives the maximum value with respect to the specified comparison function. Read more
1.6.0Source
fn min_by_key<B, F>(self, f: F) -> Option<Self::Item>where
    B: Ord,
    Self: Sized,
    F: FnMut(&Self::Item) -> B,
Returns the element that gives the minimum value from the specified function. Read more
1.15.0Source
fn min_by<F>(self, compare: F) -> Option<Self::Item>where
    Self: Sized,
    F: FnMut(&Self::Item, &Self::Item) -> Ordering,
Returns the element that gives the minimum value with respect to the specified comparison function. Read more
1.0.0Source
fn rev(self) -> Rev<Self> ⓘwhere
    Self: Sized + DoubleEndedIterator,
Reverses an iterator’s direction. Read more
1.0.0Source
fn unzip<A, B, FromA, FromB>(self) -> (FromA, FromB)where
    FromA: Default + Extend<A>,
    FromB: Default + Extend<B>,
    Self: Sized + Iterator<Item = (A, B)>,
Converts an iterator of pairs into a pair of containers. Read more
1.36.0Source
fn copied<'a, T>(self) -> Copied<Self> ⓘwhere
    T: Copy + 'a,
    Self: Sized + Iterator<Item = &'a T>,
Creates an iterator which copies all of its elements. Read more
1.0.0Source
fn cloned<'a, T>(self) -> Cloned<Self> ⓘwhere
    T: Clone + 'a,
    Self: Sized + Iterator<Item = &'a T>,
Creates an iterator which clones all of its elements. Read more
1.0.0Source
fn cycle(self) -> Cycle<Self> ⓘwhere
    Self: Sized + Clone,
Repeats an iterator endlessly. Read more
Source
fn array_chunks<const N: usize>(self) -> ArrayChunks<Self, N> ⓘwhere
    Self: Sized,
🔬This is a nightly-only experimental API. (iter_array_chunks #100450)
Returns an iterator over N elements of the iterator at a time. Read more
1.11.0Source
fn sum<S>(self) -> Swhere
    Self: Sized,
    S: Sum<Self::Item>,
Sums the elements of an iterator. Read more
1.11.0Source
fn product<P>(self) -> Pwhere
    Self: Sized,
    P: Product<Self::Item>,
Iterates over the entire iterator, multiplying all the elements Read more
1.5.0Source
fn cmp<I>(self, other: I) -> Orderingwhere
    I: IntoIterator<Item = Self::Item>,
    Self::Item: Ord,
    Self: Sized,
Lexicographically compares the elements of this Iterator with those of another. Read more
Source
fn cmp_by<I, F>(self, other: I, cmp: F) -> Orderingwhere
    Self: Sized,
    I: IntoIterator,
    F: FnMut(Self::Item, <I as IntoIterator>::Item) -> Ordering,
🔬This is a nightly-only experimental API. (iter_order_by #64295)
Lexicographically compares the elements of this Iterator with those of another with respect to the specified comparison function. Read more
1.5.0Source
fn partial_cmp<I>(self, other: I) -> Option<Ordering>where
    I: IntoIterator,
    Self::Item: PartialOrd<<I as IntoIterator>::Item>,
    Self: Sized,
Lexicographically compares the PartialOrd elements of this Iterator with those of another. The comparison works like short-circuit evaluation, returning a result without comparing the remaining elements. As soon as an order can be determined, the evaluation stops and a result is returned. Read more
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fn partial_cmp_by<I, F>(self, other: I, partial_cmp: F) -> Option<Ordering>where
    Self: Sized,
    I: IntoIterator,
    F: FnMut(Self::Item, <I as IntoIterator>::Item) -> Option<Ordering>,
🔬This is a nightly-only experimental API. (iter_order_by #64295)
Lexicographically compares the elements of this Iterator with those of another with respect to the specified comparison function. Read more
1.5.0Source
fn eq<I>(self, other: I) -> boolwhere
    I: IntoIterator,
    Self::Item: PartialEq<<I as IntoIterator>::Item>,
    Self: Sized,
Determines if the elements of this Iterator are equal to those of another. Read more
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fn eq_by<I, F>(self, other: I, eq: F) -> boolwhere
    Self: Sized,
    I: IntoIterator,
    F: FnMut(Self::Item, <I as IntoIterator>::Item) -> bool,
🔬This is a nightly-only experimental API. (iter_order_by #64295)
Determines if the elements of this Iterator are equal to those of another with respect to the specified equality function. Read more
1.5.0Source
fn ne<I>(self, other: I) -> boolwhere
    I: IntoIterator,
    Self::Item: PartialEq<<I as IntoIterator>::Item>,
    Self: Sized,
Determines if the elements of this Iterator are not equal to those of another. Read more
1.5.0Source
fn lt<I>(self, other: I) -> boolwhere
    I: IntoIterator,
    Self::Item: PartialOrd<<I as IntoIterator>::Item>,
    Self: Sized,
Determines if the elements of this Iterator are lexicographically less than those of another. Read more
1.5.0Source
fn le<I>(self, other: I) -> boolwhere
    I: IntoIterator,
    Self::Item: PartialOrd<<I as IntoIterator>::Item>,
    Self: Sized,
Determines if the elements of this Iterator are lexicographically less or equal to those of another. Read more
1.5.0Source
fn gt<I>(self, other: I) -> boolwhere
    I: IntoIterator,
    Self::Item: PartialOrd<<I as IntoIterator>::Item>,
    Self: Sized,
Determines if the elements of this Iterator are lexicographically greater than those of another. Read more
1.5.0Source
fn ge<I>(self, other: I) -> boolwhere
    I: IntoIterator,
    Self::Item: PartialOrd<<I as IntoIterator>::Item>,
    Self: Sized,
Determines if the elements of this Iterator are lexicographically greater than or equal to those of another. Read more
1.82.0Source
fn is_sorted(self) -> boolwhere
    Self: Sized,
    Self::Item: PartialOrd,
Checks if the elements of this iterator are sorted. Read more
1.82.0Source
fn is_sorted_by<F>(self, compare: F) -> boolwhere
    Self: Sized,
    F: FnMut(&Self::Item, &Self::Item) -> bool,
Checks if the elements of this iterator are sorted using the given comparator function. Read more
1.82.0Source
fn is_sorted_by_key<F, K>(self, f: F) -> boolwhere
    Self: Sized,
    F: FnMut(Self::Item) -> K,
    K: PartialOrd,
Checks if the elements of this iterator are sorted using the given key extraction function. Read more
1.26.0Source
impl<I> FusedIterator for Peekable<I>where
    I: FusedIterator,
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impl<I> TrustedLen for Peekable<I>where
    I: TrustedLen,

Auto Trait Implementations

impl<I> Freeze for Peekable<I>where
    I: Freeze,
    <I as Iterator>::Item: Freeze,
impl<I> RefUnwindSafe for Peekable<I>where
    I: RefUnwindSafe,
    <I as Iterator>::Item: RefUnwindSafe,
impl<I> Send for Peekable<I>where
    I: Send,
    <I as Iterator>::Item: Send,
impl<I> Sync for Peekable<I>where
    I: Sync,
    <I as Iterator>::Item: Sync,
impl<I> Unpin for Peekable<I>where
    I: Unpin,
    <I as Iterator>::Item: Unpin,
impl<I> UnwindSafe for Peekable<I>where
    I: UnwindSafe,
    <I as Iterator>::Item: UnwindSafe,

Blanket Implementations

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impl<T> Any for Twhere
    T: 'static + ?Sized,
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fn type_id(&self) -> TypeId
Gets the TypeId of self. Read more
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impl<T> Borrow<T> for Twhere
    T: ?Sized,
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fn borrow(&self) -> &T
Immutably borrows from an owned value. Read more
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impl<T> BorrowMut<T> for Twhere
    T: ?Sized,
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fn borrow_mut(&mut self) -> &mut T
Mutably borrows from an owned value. Read more
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impl<T> CloneToUninit for Twhere
    T: Clone,
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unsafe fn clone_to_uninit(&self, dest: *mut u8)
🔬This is a nightly-only experimental API. (clone_to_uninit #126799)
Performs copy-assignment from self to dest. Read more
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impl<T> From<T> for T
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fn from(t: T) -> T

Returns the argument unchanged.

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impl<T, U> Into<U> for Twhere
    U: From<T>,
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fn into(self) -> U

Calls U::from(self).

That is, this conversion is whatever the implementation of From<T> for U chooses to do.

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impl<I> IntoIterator for Iwhere
    I: Iterator,
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type Item = <I as Iterator>::Item
The type of the elements being iterated over.
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type IntoIter = I
Which kind of iterator are we turning this into?
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fn into_iter(self) -> I
Creates an iterator from a value. Read more
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impl<T> ToOwned for Twhere
    T: Clone,
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type Owned = T
The resulting type after obtaining ownership.
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fn to_owned(&self) -> T
Creates owned data from borrowed data, usually by cloning. Read more
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fn clone_into(&self, target: &mut T)
Uses borrowed data to replace owned data, usually by cloning. Read more
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impl<T, U> TryFrom<U> for Twhere
    U: Into<T>,
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type Error = Infallible
The type returned in the event of a conversion error.
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fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>
Performs the conversion.
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impl<T, U> TryInto<U> for Twhere
    U: TryFrom<T>,
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type Error = <U as TryFrom<T>>::Error
The type returned in the event of a conversion error.
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fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>
Performs the conversion.

© 2010 The Rust Project Developers
Licensed under the Apache License, Version 2.0 or the MIT license, at your option.
https://doc.rust-lang.org/std/iter/struct.Peekable.html