use core::num::NonZero;
use crate::iter::adapters::zip::try_get_unchecked;
use crate::iter::adapters::{SourceIter, TrustedRandomAccess, TrustedRandomAccessNoCoerce};
use crate::iter::{FusedIterator, InPlaceIterable, TrustedLen, UncheckedIterator};
use crate::ops::Try;
#[stable(feature = "iter_cloned", since = "1.1.0")]
#[must_use = "iterators are lazy and do nothing unless consumed"]
#[derive(Clone, Debug)]
pub struct Cloned<I> {
    it: I,
}
impl<I> Cloned<I> {
    pub(in crate::iter) fn new(it: I) -> Cloned<I> {
        Cloned { it }
    }
}
fn clone_try_fold<T: Clone, Acc, R>(mut f: impl FnMut(Acc, T) -> R) -> impl FnMut(Acc, &T) -> R {
    move |acc, elt| f(acc, elt.clone())
}
#[stable(feature = "iter_cloned", since = "1.1.0")]
impl<'a, I, T: 'a> Iterator for Cloned<I>
where
    I: Iterator<Item = &'a T>,
    T: Clone,
{
    type Item = T;
    fn next(&mut self) -> Option<T> {
        self.it.next().cloned()
    }
    fn size_hint(&self) -> (usize, Option<usize>) {
        self.it.size_hint()
    }
    fn try_fold<B, F, R>(&mut self, init: B, f: F) -> R
    where
        Self: Sized,
        F: FnMut(B, Self::Item) -> R,
        R: Try<Output = B>,
    {
        self.it.try_fold(init, clone_try_fold(f))
    }
    fn fold<Acc, F>(self, init: Acc, f: F) -> Acc
    where
        F: FnMut(Acc, Self::Item) -> Acc,
    {
        self.it.map(T::clone).fold(init, f)
    }
    unsafe fn __iterator_get_unchecked(&mut self, idx: usize) -> T
    where
        Self: TrustedRandomAccessNoCoerce,
    {
        unsafe { try_get_unchecked(&mut self.it, idx).clone() }
    }
}
#[stable(feature = "iter_cloned", since = "1.1.0")]
impl<'a, I, T: 'a> DoubleEndedIterator for Cloned<I>
where
    I: DoubleEndedIterator<Item = &'a T>,
    T: Clone,
{
    fn next_back(&mut self) -> Option<T> {
        self.it.next_back().cloned()
    }
    fn try_rfold<B, F, R>(&mut self, init: B, f: F) -> R
    where
        Self: Sized,
        F: FnMut(B, Self::Item) -> R,
        R: Try<Output = B>,
    {
        self.it.try_rfold(init, clone_try_fold(f))
    }
    fn rfold<Acc, F>(self, init: Acc, f: F) -> Acc
    where
        F: FnMut(Acc, Self::Item) -> Acc,
    {
        self.it.map(T::clone).rfold(init, f)
    }
}
#[stable(feature = "iter_cloned", since = "1.1.0")]
impl<'a, I, T: 'a> ExactSizeIterator for Cloned<I>
where
    I: ExactSizeIterator<Item = &'a T>,
    T: Clone,
{
    fn len(&self) -> usize {
        self.it.len()
    }
    fn is_empty(&self) -> bool {
        self.it.is_empty()
    }
}
#[stable(feature = "fused", since = "1.26.0")]
impl<'a, I, T: 'a> FusedIterator for Cloned<I>
where
    I: FusedIterator<Item = &'a T>,
    T: Clone,
{
}
#[doc(hidden)]
#[unstable(feature = "trusted_random_access", issue = "none")]
unsafe impl<I> TrustedRandomAccess for Cloned<I> where I: TrustedRandomAccess {}
#[doc(hidden)]
#[unstable(feature = "trusted_random_access", issue = "none")]
unsafe impl<I> TrustedRandomAccessNoCoerce for Cloned<I>
where
    I: TrustedRandomAccessNoCoerce,
{
    const MAY_HAVE_SIDE_EFFECT: bool = true;
}
#[unstable(feature = "trusted_len", issue = "37572")]
unsafe impl<'a, I, T: 'a> TrustedLen for Cloned<I>
where
    I: TrustedLen<Item = &'a T>,
    T: Clone,
{
}
impl<'a, I, T: 'a> UncheckedIterator for Cloned<I>
where
    I: UncheckedIterator<Item = &'a T>,
    T: Clone,
{
    unsafe fn next_unchecked(&mut self) -> T {
        let item = unsafe { self.it.next_unchecked() };
        item.clone()
    }
}
#[stable(feature = "default_iters", since = "1.70.0")]
impl<I: Default> Default for Cloned<I> {
    fn default() -> Self {
        Self::new(Default::default())
    }
}
#[unstable(issue = "none", feature = "inplace_iteration")]
unsafe impl<I> SourceIter for Cloned<I>
where
    I: SourceIter,
{
    type Source = I::Source;
    #[inline]
    unsafe fn as_inner(&mut self) -> &mut I::Source {
        unsafe { SourceIter::as_inner(&mut self.it) }
    }
}
#[unstable(issue = "none", feature = "inplace_iteration")]
unsafe impl<I: InPlaceIterable> InPlaceIterable for Cloned<I> {
    const EXPAND_BY: Option<NonZero<usize>> = I::EXPAND_BY;
    const MERGE_BY: Option<NonZero<usize>> = I::MERGE_BY;
}