core/iter/adapters/
by_ref_sized.rsuse crate::num::NonZero;
use crate::ops::{NeverShortCircuit, Try};
#[unstable(feature = "std_internals", issue = "none")]
#[derive(Debug)]
pub struct ByRefSized<'a, I>(pub &'a mut I);
#[unstable(feature = "std_internals", issue = "none")]
impl<I: Iterator> Iterator for ByRefSized<'_, I> {
    type Item = I::Item;
    #[inline]
    fn next(&mut self) -> Option<Self::Item> {
        I::next(self.0)
    }
    #[inline]
    fn size_hint(&self) -> (usize, Option<usize>) {
        I::size_hint(self.0)
    }
    #[inline]
    fn advance_by(&mut self, n: usize) -> Result<(), NonZero<usize>> {
        I::advance_by(self.0, n)
    }
    #[inline]
    fn nth(&mut self, n: usize) -> Option<Self::Item> {
        I::nth(self.0, n)
    }
    #[inline]
    fn fold<B, F>(self, init: B, f: F) -> B
    where
        F: FnMut(B, Self::Item) -> B,
    {
        I::try_fold(self.0, init, NeverShortCircuit::wrap_mut_2(f)).0
    }
    #[inline]
    fn try_fold<B, F, R>(&mut self, init: B, f: F) -> R
    where
        F: FnMut(B, Self::Item) -> R,
        R: Try<Output = B>,
    {
        I::try_fold(self.0, init, f)
    }
}
#[unstable(feature = "std_internals", issue = "none")]
impl<I: DoubleEndedIterator> DoubleEndedIterator for ByRefSized<'_, I> {
    #[inline]
    fn next_back(&mut self) -> Option<Self::Item> {
        I::next_back(self.0)
    }
    #[inline]
    fn advance_back_by(&mut self, n: usize) -> Result<(), NonZero<usize>> {
        I::advance_back_by(self.0, n)
    }
    #[inline]
    fn nth_back(&mut self, n: usize) -> Option<Self::Item> {
        I::nth_back(self.0, n)
    }
    #[inline]
    fn rfold<B, F>(self, init: B, f: F) -> B
    where
        F: FnMut(B, Self::Item) -> B,
    {
        I::try_rfold(self.0, init, NeverShortCircuit::wrap_mut_2(f)).0
    }
    #[inline]
    fn try_rfold<B, F, R>(&mut self, init: B, f: F) -> R
    where
        F: FnMut(B, Self::Item) -> R,
        R: Try<Output = B>,
    {
        I::try_rfold(self.0, init, f)
    }
}