impl<I> PeekNth<I>

fn peek(self: &mut Self) -> Option<&<I as >::Item>

Works exactly like the peek method in std::iter::Peekable.

fn peek_mut(self: &mut Self) -> Option<&mut <I as >::Item>

Works exactly like the peek_mut method in std::iter::Peekable.

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

Returns a reference to the nth value without advancing the iterator.

Examples

Basic usage:

use itertools::peek_nth;

let xs = vec![1, 2, 3];
let mut iter = peek_nth(xs.into_iter());

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

// The iterator does not advance even if we call `peek_nth` multiple times
assert_eq!(iter.peek_nth(0), Some(&2));
assert_eq!(iter.peek_nth(1), Some(&3));
assert_eq!(iter.next(), Some(2));

// Calling `peek_nth` past the end of the iterator will return `None`
assert_eq!(iter.peek_nth(1), None);

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

Returns a mutable reference to the nth value without advancing the iterator.

Examples

Basic usage:

use itertools::peek_nth;

let xs = vec![1, 2, 3, 4, 5];
let mut iter = peek_nth(xs.into_iter());

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

// The iterator does not advance even if we call `peek_nth_mut` multiple times
assert_eq!(iter.peek_nth_mut(0), Some(&mut 2));
assert_eq!(iter.peek_nth_mut(1), Some(&mut 3));
assert_eq!(iter.next(), Some(2));

// Peek into the iterator and set the value behind the mutable reference.
if let Some(p) = iter.peek_nth_mut(1) {
    assert_eq!(*p, 4);
    *p = 9;
}

// The value we put in reappears as the iterator continues.
assert_eq!(iter.next(), Some(3));
assert_eq!(iter.next(), Some(9));

// Calling `peek_nth_mut` past the end of the iterator will return `None`
assert_eq!(iter.peek_nth_mut(1), None);

fn next_if<impl FnOnce(&I::Item) -> bool: FnOnce(&<I as >::Item) -> bool>(self: &mut Self, func: impl FnOnce(&<I as >::Item) -> bool) -> Option<<I as >::Item>

Works exactly like the next_if method in std::iter::Peekable.

fn next_if_eq<T>(self: &mut Self, expected: &T) -> Option<<I as >::Item>
where
    T: ?Sized,
    <I as >::Item: PartialEq<T>

Works exactly like the next_if_eq method in std::iter::Peekable.

impl<I> Clone for PeekNth<I>

fn clone(self: &Self) -> PeekNth<I>

impl<I> Debug for PeekNth<I>

fn fmt(self: &Self, f: &mut Formatter<'_>) -> Result

impl<I> ExactSizeIterator for PeekNth<I>

impl<I> Freeze for PeekNth<I>

impl<I> IntoIterator for PeekNth<I>

fn into_iter(self: Self) -> I

impl<I> Iterator for PeekNth<I>

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

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

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

impl<I> PeekingNext for PeekNth<I>

fn peeking_next<F>(self: &mut Self, accept: F) -> Option<<Self as >::Item>
where
    F: FnOnce(&<Self as >::Item) -> bool

impl<I> RefUnwindSafe for PeekNth<I>

impl<I> Send for PeekNth<I>

impl<I> Sync for PeekNth<I>

impl<I> Unpin for PeekNth<I>

impl<I> UnsafeUnpin for PeekNth<I>

impl<I> UnwindSafe for PeekNth<I>

impl<IT> MultiUnzip for PeekNth<I>

fn multiunzip(self: Self)

impl<IT, A, FromA> MultiUnzip for PeekNth<I>

fn multiunzip(self: Self) -> (FromA)

impl<IT, A, FromA, B, FromB> MultiUnzip for PeekNth<I>

fn multiunzip(self: Self) -> (FromA, FromB)

impl<IT, A, FromA, B, FromB, C, FromC> MultiUnzip for PeekNth<I>

fn multiunzip(self: Self) -> (FromA, FromB, FromC)

impl<IT, A, FromA, B, FromB, C, FromC, D, FromD> MultiUnzip for PeekNth<I>

fn multiunzip(self: Self) -> (FromA, FromB, FromC, FromD)

impl<IT, A, FromA, B, FromB, C, FromC, D, FromD, E, FromE> MultiUnzip for PeekNth<I>

fn multiunzip(self: Self) -> (FromA, FromB, FromC, FromD, FromE)

impl<IT, A, FromA, B, FromB, C, FromC, D, FromD, E, FromE, F, FromF> MultiUnzip for PeekNth<I>

fn multiunzip(self: Self) -> (FromA, FromB, FromC, FromD, FromE, FromF)

impl<IT, A, FromA, B, FromB, C, FromC, D, FromD, E, FromE, F, FromF, G, FromG> MultiUnzip for PeekNth<I>

fn multiunzip(self: Self) -> (FromA, FromB, FromC, FromD, FromE, FromF, FromG)

impl<IT, A, FromA, B, FromB, C, FromC, D, FromD, E, FromE, F, FromF, G, FromG, H, FromH> MultiUnzip for PeekNth<I>

fn multiunzip(self: Self) -> (FromA, FromB, FromC, FromD, FromE, FromF, FromG, FromH)

impl<IT, A, FromA, B, FromB, C, FromC, D, FromD, E, FromE, F, FromF, G, FromG, H, FromH, I, FromI> MultiUnzip for PeekNth<I>

fn multiunzip(self: Self) -> (FromA, FromB, FromC, FromD, FromE, FromF, FromG, FromH, FromI)

impl<IT, A, FromA, B, FromB, C, FromC, D, FromD, E, FromE, F, FromF, G, FromG, H, FromH, I, FromI, J, FromJ> MultiUnzip for PeekNth<I>

fn multiunzip(self: Self) -> (FromA, FromB, FromC, FromD, FromE, FromF, FromG, FromH, FromI, FromJ)

impl<IT, A, FromA, B, FromB, C, FromC, D, FromD, E, FromE, F, FromF, G, FromG, H, FromH, I, FromI, J, FromJ, K, FromK> MultiUnzip for PeekNth<I>

fn multiunzip(self: Self) -> (FromA, FromB, FromC, FromD, FromE, FromF, FromG, FromH, FromI, FromJ, FromK)

impl<IT, A, FromA, B, FromB, C, FromC, D, FromD, E, FromE, F, FromF, G, FromG, H, FromH, I, FromI, J, FromJ, K, FromK, L, FromL> MultiUnzip for PeekNth<I>

fn multiunzip(self: Self) -> (FromA, FromB, FromC, FromD, FromE, FromF, FromG, FromH, FromI, FromJ, FromK, FromL)

impl<T> Any for PeekNth<I>

fn type_id(self: &Self) -> TypeId

impl<T> Borrow for PeekNth<I>

fn borrow(self: &Self) -> &T

impl<T> BorrowMut for PeekNth<I>

fn borrow_mut(self: &mut Self) -> &mut T

impl<T> CloneToUninit for PeekNth<I>

unsafe fn clone_to_uninit(self: &Self, dest: *mut u8)

impl<T> From for PeekNth<I>

fn from(t: T) -> T

Returns the argument unchanged.

impl<T> Itertools for PeekNth<I>

impl<T> ToOwned for PeekNth<I>

fn to_owned(self: &Self) -> T

fn clone_into(self: &Self, target: &mut T)

impl<T, U> Into for PeekNth<I>

fn into(self: Self) -> U

Calls U::from(self).

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

impl<T, U> TryFrom for PeekNth<I>

fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>

impl<T, U> TryInto for PeekNth<I>

fn try_into(self: Self) -> Result<U, <U as TryFrom<T>>::Error>