#[macro_use] mod macros;
use crate::cmp;
use crate::fmt;
use crate::hint::assert_unchecked;
use crate::iter::{
    FusedIterator, TrustedLen, TrustedRandomAccess, TrustedRandomAccessNoCoerce, UncheckedIterator,
};
use crate::marker::PhantomData;
use crate::mem::{self, SizedTypeProperties};
use crate::num::NonZero;
use crate::ptr::{self, without_provenance, without_provenance_mut, NonNull};
use super::{from_raw_parts, from_raw_parts_mut};
#[stable(feature = "boxed_slice_into_iter", since = "1.80.0")]
impl<T> !Iterator for [T] {}
#[stable(feature = "rust1", since = "1.0.0")]
impl<'a, T> IntoIterator for &'a [T] {
    type Item = &'a T;
    type IntoIter = Iter<'a, T>;
    fn into_iter(self) -> Iter<'a, T> {
        self.iter()
    }
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<'a, T> IntoIterator for &'a mut [T] {
    type Item = &'a mut T;
    type IntoIter = IterMut<'a, T>;
    fn into_iter(self) -> IterMut<'a, T> {
        self.iter_mut()
    }
}
#[stable(feature = "rust1", since = "1.0.0")]
#[must_use = "iterators are lazy and do nothing unless consumed"]
#[rustc_diagnostic_item = "SliceIter"]
pub struct Iter<'a, T: 'a> {
    ptr: NonNull<T>,
    end_or_len: *const T,
    _marker: PhantomData<&'a T>,
}
#[stable(feature = "core_impl_debug", since = "1.9.0")]
impl<T: fmt::Debug> fmt::Debug for Iter<'_, T> {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        f.debug_tuple("Iter").field(&self.as_slice()).finish()
    }
}
#[stable(feature = "rust1", since = "1.0.0")]
unsafe impl<T: Sync> Sync for Iter<'_, T> {}
#[stable(feature = "rust1", since = "1.0.0")]
unsafe impl<T: Sync> Send for Iter<'_, T> {}
impl<'a, T> Iter<'a, T> {
    #[inline]
    pub(super) fn new(slice: &'a [T]) -> Self {
        let len = slice.len();
        let ptr: NonNull<T> = NonNull::from(slice).cast();
        unsafe {
            let end_or_len =
                if T::IS_ZST { without_provenance(len) } else { ptr.as_ptr().add(len) };
            Self { ptr, end_or_len, _marker: PhantomData }
        }
    }
    #[must_use]
    #[stable(feature = "iter_to_slice", since = "1.4.0")]
    #[inline]
    pub fn as_slice(&self) -> &'a [T] {
        self.make_slice()
    }
}
iterator! {struct Iter -> *const T, &'a T, const, {}, as_ref, {
    fn is_sorted_by<F>(self, mut compare: F) -> bool
    where
        Self: Sized,
        F: FnMut(&Self::Item, &Self::Item) -> bool,
    {
        self.as_slice().is_sorted_by(|a, b| compare(&a, &b))
    }
}}
#[stable(feature = "rust1", since = "1.0.0")]
impl<T> Clone for Iter<'_, T> {
    #[inline]
    fn clone(&self) -> Self {
        Iter { ptr: self.ptr, end_or_len: self.end_or_len, _marker: self._marker }
    }
}
#[stable(feature = "slice_iter_as_ref", since = "1.13.0")]
impl<T> AsRef<[T]> for Iter<'_, T> {
    #[inline]
    fn as_ref(&self) -> &[T] {
        self.as_slice()
    }
}
#[stable(feature = "rust1", since = "1.0.0")]
#[must_use = "iterators are lazy and do nothing unless consumed"]
pub struct IterMut<'a, T: 'a> {
    ptr: NonNull<T>,
    end_or_len: *mut T,
    _marker: PhantomData<&'a mut T>,
}
#[stable(feature = "core_impl_debug", since = "1.9.0")]
impl<T: fmt::Debug> fmt::Debug for IterMut<'_, T> {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        f.debug_tuple("IterMut").field(&self.make_slice()).finish()
    }
}
#[stable(feature = "rust1", since = "1.0.0")]
unsafe impl<T: Sync> Sync for IterMut<'_, T> {}
#[stable(feature = "rust1", since = "1.0.0")]
unsafe impl<T: Send> Send for IterMut<'_, T> {}
impl<'a, T> IterMut<'a, T> {
    #[inline]
    pub(super) fn new(slice: &'a mut [T]) -> Self {
        let len = slice.len();
        let ptr: NonNull<T> = NonNull::from(slice).cast();
        unsafe {
            let end_or_len =
                if T::IS_ZST { without_provenance_mut(len) } else { ptr.as_ptr().add(len) };
            Self { ptr, end_or_len, _marker: PhantomData }
        }
    }
    #[must_use = "`self` will be dropped if the result is not used"]
    #[stable(feature = "iter_to_slice", since = "1.4.0")]
    pub fn into_slice(self) -> &'a mut [T] {
        unsafe { from_raw_parts_mut(self.ptr.as_ptr(), len!(self)) }
    }
    #[must_use]
    #[stable(feature = "slice_iter_mut_as_slice", since = "1.53.0")]
    #[inline]
    pub fn as_slice(&self) -> &[T] {
        self.make_slice()
    }
    #[must_use]
    #[unstable(feature = "slice_iter_mut_as_mut_slice", issue = "93079")]
    pub fn as_mut_slice(&mut self) -> &mut [T] {
        unsafe { from_raw_parts_mut(self.ptr.as_ptr(), len!(self)) }
    }
}
#[stable(feature = "slice_iter_mut_as_slice", since = "1.53.0")]
impl<T> AsRef<[T]> for IterMut<'_, T> {
    #[inline]
    fn as_ref(&self) -> &[T] {
        self.as_slice()
    }
}
iterator! {struct IterMut -> *mut T, &'a mut T, mut, {mut}, as_mut, {}}
#[doc(hidden)]
pub(super) trait SplitIter: DoubleEndedIterator {
    fn finish(&mut self) -> Option<Self::Item>;
}
#[stable(feature = "rust1", since = "1.0.0")]
#[must_use = "iterators are lazy and do nothing unless consumed"]
pub struct Split<'a, T: 'a, P>
where
    P: FnMut(&T) -> bool,
{
    pub(crate) v: &'a [T],
    pred: P,
    pub(crate) finished: bool,
}
impl<'a, T: 'a, P: FnMut(&T) -> bool> Split<'a, T, P> {
    #[inline]
    pub(super) fn new(slice: &'a [T], pred: P) -> Self {
        Self { v: slice, pred, finished: false }
    }
    #[unstable(feature = "split_as_slice", issue = "96137")]
    pub fn as_slice(&self) -> &'a [T] {
        if self.finished { &[] } else { &self.v }
    }
}
#[stable(feature = "core_impl_debug", since = "1.9.0")]
impl<T: fmt::Debug, P> fmt::Debug for Split<'_, T, P>
where
    P: FnMut(&T) -> bool,
{
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        f.debug_struct("Split").field("v", &self.v).field("finished", &self.finished).finish()
    }
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<T, P> Clone for Split<'_, T, P>
where
    P: Clone + FnMut(&T) -> bool,
{
    fn clone(&self) -> Self {
        Split { v: self.v, pred: self.pred.clone(), finished: self.finished }
    }
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<'a, T, P> Iterator for Split<'a, T, P>
where
    P: FnMut(&T) -> bool,
{
    type Item = &'a [T];
    #[inline]
    fn next(&mut self) -> Option<&'a [T]> {
        if self.finished {
            return None;
        }
        match self.v.iter().position(|x| (self.pred)(x)) {
            None => self.finish(),
            Some(idx) => {
                let (left, right) =
                    unsafe { (self.v.get_unchecked(..idx), self.v.get_unchecked(idx + 1..)) };
                let ret = Some(left);
                self.v = right;
                ret
            }
        }
    }
    #[inline]
    fn size_hint(&self) -> (usize, Option<usize>) {
        if self.finished {
            (0, Some(0))
        } else {
            (1, Some(self.v.len() + 1))
        }
    }
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<'a, T, P> DoubleEndedIterator for Split<'a, T, P>
where
    P: FnMut(&T) -> bool,
{
    #[inline]
    fn next_back(&mut self) -> Option<&'a [T]> {
        if self.finished {
            return None;
        }
        match self.v.iter().rposition(|x| (self.pred)(x)) {
            None => self.finish(),
            Some(idx) => {
                let (left, right) =
                    unsafe { (self.v.get_unchecked(..idx), self.v.get_unchecked(idx + 1..)) };
                let ret = Some(right);
                self.v = left;
                ret
            }
        }
    }
}
impl<'a, T, P> SplitIter for Split<'a, T, P>
where
    P: FnMut(&T) -> bool,
{
    #[inline]
    fn finish(&mut self) -> Option<&'a [T]> {
        if self.finished {
            None
        } else {
            self.finished = true;
            Some(self.v)
        }
    }
}
#[stable(feature = "fused", since = "1.26.0")]
impl<T, P> FusedIterator for Split<'_, T, P> where P: FnMut(&T) -> bool {}
#[stable(feature = "split_inclusive", since = "1.51.0")]
#[must_use = "iterators are lazy and do nothing unless consumed"]
pub struct SplitInclusive<'a, T: 'a, P>
where
    P: FnMut(&T) -> bool,
{
    v: &'a [T],
    pred: P,
    finished: bool,
}
impl<'a, T: 'a, P: FnMut(&T) -> bool> SplitInclusive<'a, T, P> {
    #[inline]
    pub(super) fn new(slice: &'a [T], pred: P) -> Self {
        let finished = slice.is_empty();
        Self { v: slice, pred, finished }
    }
}
#[stable(feature = "split_inclusive", since = "1.51.0")]
impl<T: fmt::Debug, P> fmt::Debug for SplitInclusive<'_, T, P>
where
    P: FnMut(&T) -> bool,
{
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        f.debug_struct("SplitInclusive")
            .field("v", &self.v)
            .field("finished", &self.finished)
            .finish()
    }
}
#[stable(feature = "split_inclusive", since = "1.51.0")]
impl<T, P> Clone for SplitInclusive<'_, T, P>
where
    P: Clone + FnMut(&T) -> bool,
{
    fn clone(&self) -> Self {
        SplitInclusive { v: self.v, pred: self.pred.clone(), finished: self.finished }
    }
}
#[stable(feature = "split_inclusive", since = "1.51.0")]
impl<'a, T, P> Iterator for SplitInclusive<'a, T, P>
where
    P: FnMut(&T) -> bool,
{
    type Item = &'a [T];
    #[inline]
    fn next(&mut self) -> Option<&'a [T]> {
        if self.finished {
            return None;
        }
        let idx =
            self.v.iter().position(|x| (self.pred)(x)).map(|idx| idx + 1).unwrap_or(self.v.len());
        if idx == self.v.len() {
            self.finished = true;
        }
        let ret = Some(&self.v[..idx]);
        self.v = &self.v[idx..];
        ret
    }
    #[inline]
    fn size_hint(&self) -> (usize, Option<usize>) {
        if self.finished {
            (0, Some(0))
        } else {
            (1, Some(cmp::max(1, self.v.len())))
        }
    }
}
#[stable(feature = "split_inclusive", since = "1.51.0")]
impl<'a, T, P> DoubleEndedIterator for SplitInclusive<'a, T, P>
where
    P: FnMut(&T) -> bool,
{
    #[inline]
    fn next_back(&mut self) -> Option<&'a [T]> {
        if self.finished {
            return None;
        }
        let remainder = if self.v.is_empty() { &[] } else { &self.v[..(self.v.len() - 1)] };
        let idx = remainder.iter().rposition(|x| (self.pred)(x)).map(|idx| idx + 1).unwrap_or(0);
        if idx == 0 {
            self.finished = true;
        }
        let ret = Some(&self.v[idx..]);
        self.v = &self.v[..idx];
        ret
    }
}
#[stable(feature = "split_inclusive", since = "1.51.0")]
impl<T, P> FusedIterator for SplitInclusive<'_, T, P> where P: FnMut(&T) -> bool {}
#[stable(feature = "rust1", since = "1.0.0")]
#[must_use = "iterators are lazy and do nothing unless consumed"]
pub struct SplitMut<'a, T: 'a, P>
where
    P: FnMut(&T) -> bool,
{
    v: &'a mut [T],
    pred: P,
    finished: bool,
}
impl<'a, T: 'a, P: FnMut(&T) -> bool> SplitMut<'a, T, P> {
    #[inline]
    pub(super) fn new(slice: &'a mut [T], pred: P) -> Self {
        Self { v: slice, pred, finished: false }
    }
}
#[stable(feature = "core_impl_debug", since = "1.9.0")]
impl<T: fmt::Debug, P> fmt::Debug for SplitMut<'_, T, P>
where
    P: FnMut(&T) -> bool,
{
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        f.debug_struct("SplitMut").field("v", &self.v).field("finished", &self.finished).finish()
    }
}
impl<'a, T, P> SplitIter for SplitMut<'a, T, P>
where
    P: FnMut(&T) -> bool,
{
    #[inline]
    fn finish(&mut self) -> Option<&'a mut [T]> {
        if self.finished {
            None
        } else {
            self.finished = true;
            Some(mem::take(&mut self.v))
        }
    }
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<'a, T, P> Iterator for SplitMut<'a, T, P>
where
    P: FnMut(&T) -> bool,
{
    type Item = &'a mut [T];
    #[inline]
    fn next(&mut self) -> Option<&'a mut [T]> {
        if self.finished {
            return None;
        }
        match self.v.iter().position(|x| (self.pred)(x)) {
            None => self.finish(),
            Some(idx) => {
                let tmp = mem::take(&mut self.v);
                let (head, tail) = tmp.split_at_mut(idx + 1);
                self.v = tail;
                Some(&mut head[..idx])
            }
        }
    }
    #[inline]
    fn size_hint(&self) -> (usize, Option<usize>) {
        if self.finished {
            (0, Some(0))
        } else {
            (1, Some(self.v.len() + 1))
        }
    }
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<'a, T, P> DoubleEndedIterator for SplitMut<'a, T, P>
where
    P: FnMut(&T) -> bool,
{
    #[inline]
    fn next_back(&mut self) -> Option<&'a mut [T]> {
        if self.finished {
            return None;
        }
        let idx_opt = {
            let pred = &mut self.pred;
            self.v.iter().rposition(|x| (*pred)(x))
        };
        match idx_opt {
            None => self.finish(),
            Some(idx) => {
                let tmp = mem::take(&mut self.v);
                let (head, tail) = tmp.split_at_mut(idx);
                self.v = head;
                Some(&mut tail[1..])
            }
        }
    }
}
#[stable(feature = "fused", since = "1.26.0")]
impl<T, P> FusedIterator for SplitMut<'_, T, P> where P: FnMut(&T) -> bool {}
#[stable(feature = "split_inclusive", since = "1.51.0")]
#[must_use = "iterators are lazy and do nothing unless consumed"]
pub struct SplitInclusiveMut<'a, T: 'a, P>
where
    P: FnMut(&T) -> bool,
{
    v: &'a mut [T],
    pred: P,
    finished: bool,
}
impl<'a, T: 'a, P: FnMut(&T) -> bool> SplitInclusiveMut<'a, T, P> {
    #[inline]
    pub(super) fn new(slice: &'a mut [T], pred: P) -> Self {
        let finished = slice.is_empty();
        Self { v: slice, pred, finished }
    }
}
#[stable(feature = "split_inclusive", since = "1.51.0")]
impl<T: fmt::Debug, P> fmt::Debug for SplitInclusiveMut<'_, T, P>
where
    P: FnMut(&T) -> bool,
{
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        f.debug_struct("SplitInclusiveMut")
            .field("v", &self.v)
            .field("finished", &self.finished)
            .finish()
    }
}
#[stable(feature = "split_inclusive", since = "1.51.0")]
impl<'a, T, P> Iterator for SplitInclusiveMut<'a, T, P>
where
    P: FnMut(&T) -> bool,
{
    type Item = &'a mut [T];
    #[inline]
    fn next(&mut self) -> Option<&'a mut [T]> {
        if self.finished {
            return None;
        }
        let idx_opt = {
            let pred = &mut self.pred;
            self.v.iter().position(|x| (*pred)(x))
        };
        let idx = idx_opt.map(|idx| idx + 1).unwrap_or(self.v.len());
        if idx == self.v.len() {
            self.finished = true;
        }
        let tmp = mem::take(&mut self.v);
        let (head, tail) = tmp.split_at_mut(idx);
        self.v = tail;
        Some(head)
    }
    #[inline]
    fn size_hint(&self) -> (usize, Option<usize>) {
        if self.finished {
            (0, Some(0))
        } else {
            (1, Some(cmp::max(1, self.v.len())))
        }
    }
}
#[stable(feature = "split_inclusive", since = "1.51.0")]
impl<'a, T, P> DoubleEndedIterator for SplitInclusiveMut<'a, T, P>
where
    P: FnMut(&T) -> bool,
{
    #[inline]
    fn next_back(&mut self) -> Option<&'a mut [T]> {
        if self.finished {
            return None;
        }
        let idx_opt = if self.v.is_empty() {
            None
        } else {
            let pred = &mut self.pred;
            let remainder = &self.v[..(self.v.len() - 1)];
            remainder.iter().rposition(|x| (*pred)(x))
        };
        let idx = idx_opt.map(|idx| idx + 1).unwrap_or(0);
        if idx == 0 {
            self.finished = true;
        }
        let tmp = mem::take(&mut self.v);
        let (head, tail) = tmp.split_at_mut(idx);
        self.v = head;
        Some(tail)
    }
}
#[stable(feature = "split_inclusive", since = "1.51.0")]
impl<T, P> FusedIterator for SplitInclusiveMut<'_, T, P> where P: FnMut(&T) -> bool {}
#[stable(feature = "slice_rsplit", since = "1.27.0")]
#[must_use = "iterators are lazy and do nothing unless consumed"]
pub struct RSplit<'a, T: 'a, P>
where
    P: FnMut(&T) -> bool,
{
    inner: Split<'a, T, P>,
}
impl<'a, T: 'a, P: FnMut(&T) -> bool> RSplit<'a, T, P> {
    #[inline]
    pub(super) fn new(slice: &'a [T], pred: P) -> Self {
        Self { inner: Split::new(slice, pred) }
    }
}
#[stable(feature = "slice_rsplit", since = "1.27.0")]
impl<T: fmt::Debug, P> fmt::Debug for RSplit<'_, T, P>
where
    P: FnMut(&T) -> bool,
{
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        f.debug_struct("RSplit")
            .field("v", &self.inner.v)
            .field("finished", &self.inner.finished)
            .finish()
    }
}
#[stable(feature = "slice_rsplit", since = "1.27.0")]
impl<T, P> Clone for RSplit<'_, T, P>
where
    P: Clone + FnMut(&T) -> bool,
{
    fn clone(&self) -> Self {
        RSplit { inner: self.inner.clone() }
    }
}
#[stable(feature = "slice_rsplit", since = "1.27.0")]
impl<'a, T, P> Iterator for RSplit<'a, T, P>
where
    P: FnMut(&T) -> bool,
{
    type Item = &'a [T];
    #[inline]
    fn next(&mut self) -> Option<&'a [T]> {
        self.inner.next_back()
    }
    #[inline]
    fn size_hint(&self) -> (usize, Option<usize>) {
        self.inner.size_hint()
    }
}
#[stable(feature = "slice_rsplit", since = "1.27.0")]
impl<'a, T, P> DoubleEndedIterator for RSplit<'a, T, P>
where
    P: FnMut(&T) -> bool,
{
    #[inline]
    fn next_back(&mut self) -> Option<&'a [T]> {
        self.inner.next()
    }
}
#[stable(feature = "slice_rsplit", since = "1.27.0")]
impl<'a, T, P> SplitIter for RSplit<'a, T, P>
where
    P: FnMut(&T) -> bool,
{
    #[inline]
    fn finish(&mut self) -> Option<&'a [T]> {
        self.inner.finish()
    }
}
#[stable(feature = "slice_rsplit", since = "1.27.0")]
impl<T, P> FusedIterator for RSplit<'_, T, P> where P: FnMut(&T) -> bool {}
#[stable(feature = "slice_rsplit", since = "1.27.0")]
#[must_use = "iterators are lazy and do nothing unless consumed"]
pub struct RSplitMut<'a, T: 'a, P>
where
    P: FnMut(&T) -> bool,
{
    inner: SplitMut<'a, T, P>,
}
impl<'a, T: 'a, P: FnMut(&T) -> bool> RSplitMut<'a, T, P> {
    #[inline]
    pub(super) fn new(slice: &'a mut [T], pred: P) -> Self {
        Self { inner: SplitMut::new(slice, pred) }
    }
}
#[stable(feature = "slice_rsplit", since = "1.27.0")]
impl<T: fmt::Debug, P> fmt::Debug for RSplitMut<'_, T, P>
where
    P: FnMut(&T) -> bool,
{
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        f.debug_struct("RSplitMut")
            .field("v", &self.inner.v)
            .field("finished", &self.inner.finished)
            .finish()
    }
}
#[stable(feature = "slice_rsplit", since = "1.27.0")]
impl<'a, T, P> SplitIter for RSplitMut<'a, T, P>
where
    P: FnMut(&T) -> bool,
{
    #[inline]
    fn finish(&mut self) -> Option<&'a mut [T]> {
        self.inner.finish()
    }
}
#[stable(feature = "slice_rsplit", since = "1.27.0")]
impl<'a, T, P> Iterator for RSplitMut<'a, T, P>
where
    P: FnMut(&T) -> bool,
{
    type Item = &'a mut [T];
    #[inline]
    fn next(&mut self) -> Option<&'a mut [T]> {
        self.inner.next_back()
    }
    #[inline]
    fn size_hint(&self) -> (usize, Option<usize>) {
        self.inner.size_hint()
    }
}
#[stable(feature = "slice_rsplit", since = "1.27.0")]
impl<'a, T, P> DoubleEndedIterator for RSplitMut<'a, T, P>
where
    P: FnMut(&T) -> bool,
{
    #[inline]
    fn next_back(&mut self) -> Option<&'a mut [T]> {
        self.inner.next()
    }
}
#[stable(feature = "slice_rsplit", since = "1.27.0")]
impl<T, P> FusedIterator for RSplitMut<'_, T, P> where P: FnMut(&T) -> bool {}
#[derive(Debug)]
struct GenericSplitN<I> {
    iter: I,
    count: usize,
}
impl<T, I: SplitIter<Item = T>> Iterator for GenericSplitN<I> {
    type Item = T;
    #[inline]
    fn next(&mut self) -> Option<T> {
        match self.count {
            0 => None,
            1 => {
                self.count -= 1;
                self.iter.finish()
            }
            _ => {
                self.count -= 1;
                self.iter.next()
            }
        }
    }
    #[inline]
    fn size_hint(&self) -> (usize, Option<usize>) {
        let (lower, upper_opt) = self.iter.size_hint();
        (
            cmp::min(self.count, lower),
            Some(upper_opt.map_or(self.count, |upper| cmp::min(self.count, upper))),
        )
    }
}
#[stable(feature = "rust1", since = "1.0.0")]
#[must_use = "iterators are lazy and do nothing unless consumed"]
pub struct SplitN<'a, T: 'a, P>
where
    P: FnMut(&T) -> bool,
{
    inner: GenericSplitN<Split<'a, T, P>>,
}
impl<'a, T: 'a, P: FnMut(&T) -> bool> SplitN<'a, T, P> {
    #[inline]
    pub(super) fn new(s: Split<'a, T, P>, n: usize) -> Self {
        Self { inner: GenericSplitN { iter: s, count: n } }
    }
}
#[stable(feature = "core_impl_debug", since = "1.9.0")]
impl<T: fmt::Debug, P> fmt::Debug for SplitN<'_, T, P>
where
    P: FnMut(&T) -> bool,
{
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        f.debug_struct("SplitN").field("inner", &self.inner).finish()
    }
}
#[stable(feature = "rust1", since = "1.0.0")]
#[must_use = "iterators are lazy and do nothing unless consumed"]
pub struct RSplitN<'a, T: 'a, P>
where
    P: FnMut(&T) -> bool,
{
    inner: GenericSplitN<RSplit<'a, T, P>>,
}
impl<'a, T: 'a, P: FnMut(&T) -> bool> RSplitN<'a, T, P> {
    #[inline]
    pub(super) fn new(s: RSplit<'a, T, P>, n: usize) -> Self {
        Self { inner: GenericSplitN { iter: s, count: n } }
    }
}
#[stable(feature = "core_impl_debug", since = "1.9.0")]
impl<T: fmt::Debug, P> fmt::Debug for RSplitN<'_, T, P>
where
    P: FnMut(&T) -> bool,
{
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        f.debug_struct("RSplitN").field("inner", &self.inner).finish()
    }
}
#[stable(feature = "rust1", since = "1.0.0")]
#[must_use = "iterators are lazy and do nothing unless consumed"]
pub struct SplitNMut<'a, T: 'a, P>
where
    P: FnMut(&T) -> bool,
{
    inner: GenericSplitN<SplitMut<'a, T, P>>,
}
impl<'a, T: 'a, P: FnMut(&T) -> bool> SplitNMut<'a, T, P> {
    #[inline]
    pub(super) fn new(s: SplitMut<'a, T, P>, n: usize) -> Self {
        Self { inner: GenericSplitN { iter: s, count: n } }
    }
}
#[stable(feature = "core_impl_debug", since = "1.9.0")]
impl<T: fmt::Debug, P> fmt::Debug for SplitNMut<'_, T, P>
where
    P: FnMut(&T) -> bool,
{
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        f.debug_struct("SplitNMut").field("inner", &self.inner).finish()
    }
}
#[stable(feature = "rust1", since = "1.0.0")]
#[must_use = "iterators are lazy and do nothing unless consumed"]
pub struct RSplitNMut<'a, T: 'a, P>
where
    P: FnMut(&T) -> bool,
{
    inner: GenericSplitN<RSplitMut<'a, T, P>>,
}
impl<'a, T: 'a, P: FnMut(&T) -> bool> RSplitNMut<'a, T, P> {
    #[inline]
    pub(super) fn new(s: RSplitMut<'a, T, P>, n: usize) -> Self {
        Self { inner: GenericSplitN { iter: s, count: n } }
    }
}
#[stable(feature = "core_impl_debug", since = "1.9.0")]
impl<T: fmt::Debug, P> fmt::Debug for RSplitNMut<'_, T, P>
where
    P: FnMut(&T) -> bool,
{
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        f.debug_struct("RSplitNMut").field("inner", &self.inner).finish()
    }
}
forward_iterator! { SplitN: T, &'a [T] }
forward_iterator! { RSplitN: T, &'a [T] }
forward_iterator! { SplitNMut: T, &'a mut [T] }
forward_iterator! { RSplitNMut: T, &'a mut [T] }
#[derive(Debug)]
#[stable(feature = "rust1", since = "1.0.0")]
#[must_use = "iterators are lazy and do nothing unless consumed"]
pub struct Windows<'a, T: 'a> {
    v: &'a [T],
    size: NonZero<usize>,
}
impl<'a, T: 'a> Windows<'a, T> {
    #[inline]
    pub(super) fn new(slice: &'a [T], size: NonZero<usize>) -> Self {
        Self { v: slice, size }
    }
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<T> Clone for Windows<'_, T> {
    fn clone(&self) -> Self {
        Windows { v: self.v, size: self.size }
    }
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<'a, T> Iterator for Windows<'a, T> {
    type Item = &'a [T];
    #[inline]
    fn next(&mut self) -> Option<&'a [T]> {
        if self.size.get() > self.v.len() {
            None
        } else {
            let ret = Some(&self.v[..self.size.get()]);
            self.v = &self.v[1..];
            ret
        }
    }
    #[inline]
    fn size_hint(&self) -> (usize, Option<usize>) {
        if self.size.get() > self.v.len() {
            (0, Some(0))
        } else {
            let size = self.v.len() - self.size.get() + 1;
            (size, Some(size))
        }
    }
    #[inline]
    fn count(self) -> usize {
        self.len()
    }
    #[inline]
    fn nth(&mut self, n: usize) -> Option<Self::Item> {
        let (end, overflow) = self.size.get().overflowing_add(n);
        if end > self.v.len() || overflow {
            self.v = &[];
            None
        } else {
            let nth = &self.v[n..end];
            self.v = &self.v[n + 1..];
            Some(nth)
        }
    }
    #[inline]
    fn last(self) -> Option<Self::Item> {
        if self.size.get() > self.v.len() {
            None
        } else {
            let start = self.v.len() - self.size.get();
            Some(&self.v[start..])
        }
    }
    unsafe fn __iterator_get_unchecked(&mut self, idx: usize) -> Self::Item {
        unsafe { from_raw_parts(self.v.as_ptr().add(idx), self.size.get()) }
    }
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<'a, T> DoubleEndedIterator for Windows<'a, T> {
    #[inline]
    fn next_back(&mut self) -> Option<&'a [T]> {
        if self.size.get() > self.v.len() {
            None
        } else {
            let ret = Some(&self.v[self.v.len() - self.size.get()..]);
            self.v = &self.v[..self.v.len() - 1];
            ret
        }
    }
    #[inline]
    fn nth_back(&mut self, n: usize) -> Option<Self::Item> {
        let (end, overflow) = self.v.len().overflowing_sub(n);
        if end < self.size.get() || overflow {
            self.v = &[];
            None
        } else {
            let ret = &self.v[end - self.size.get()..end];
            self.v = &self.v[..end - 1];
            Some(ret)
        }
    }
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<T> ExactSizeIterator for Windows<'_, T> {}
#[unstable(feature = "trusted_len", issue = "37572")]
unsafe impl<T> TrustedLen for Windows<'_, T> {}
#[stable(feature = "fused", since = "1.26.0")]
impl<T> FusedIterator for Windows<'_, T> {}
#[doc(hidden)]
#[unstable(feature = "trusted_random_access", issue = "none")]
unsafe impl<'a, T> TrustedRandomAccess for Windows<'a, T> {}
#[doc(hidden)]
#[unstable(feature = "trusted_random_access", issue = "none")]
unsafe impl<'a, T> TrustedRandomAccessNoCoerce for Windows<'a, T> {
    const MAY_HAVE_SIDE_EFFECT: bool = false;
}
#[derive(Debug)]
#[stable(feature = "rust1", since = "1.0.0")]
#[must_use = "iterators are lazy and do nothing unless consumed"]
pub struct Chunks<'a, T: 'a> {
    v: &'a [T],
    chunk_size: usize,
}
impl<'a, T: 'a> Chunks<'a, T> {
    #[inline]
    pub(super) fn new(slice: &'a [T], size: usize) -> Self {
        Self { v: slice, chunk_size: size }
    }
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<T> Clone for Chunks<'_, T> {
    fn clone(&self) -> Self {
        Chunks { v: self.v, chunk_size: self.chunk_size }
    }
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<'a, T> Iterator for Chunks<'a, T> {
    type Item = &'a [T];
    #[inline]
    fn next(&mut self) -> Option<&'a [T]> {
        if self.v.is_empty() {
            None
        } else {
            let chunksz = cmp::min(self.v.len(), self.chunk_size);
            let (fst, snd) = self.v.split_at(chunksz);
            self.v = snd;
            Some(fst)
        }
    }
    #[inline]
    fn size_hint(&self) -> (usize, Option<usize>) {
        if self.v.is_empty() {
            (0, Some(0))
        } else {
            let n = self.v.len() / self.chunk_size;
            let rem = self.v.len() % self.chunk_size;
            let n = if rem > 0 { n + 1 } else { n };
            (n, Some(n))
        }
    }
    #[inline]
    fn count(self) -> usize {
        self.len()
    }
    #[inline]
    fn nth(&mut self, n: usize) -> Option<Self::Item> {
        let (start, overflow) = n.overflowing_mul(self.chunk_size);
        if start >= self.v.len() || overflow {
            self.v = &[];
            None
        } else {
            let end = match start.checked_add(self.chunk_size) {
                Some(sum) => cmp::min(self.v.len(), sum),
                None => self.v.len(),
            };
            let nth = &self.v[start..end];
            self.v = &self.v[end..];
            Some(nth)
        }
    }
    #[inline]
    fn last(self) -> Option<Self::Item> {
        if self.v.is_empty() {
            None
        } else {
            let start = (self.v.len() - 1) / self.chunk_size * self.chunk_size;
            Some(&self.v[start..])
        }
    }
    unsafe fn __iterator_get_unchecked(&mut self, idx: usize) -> Self::Item {
        let start = idx * self.chunk_size;
        unsafe {
            let len = cmp::min(self.v.len().unchecked_sub(start), self.chunk_size);
            from_raw_parts(self.v.as_ptr().add(start), len)
        }
    }
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<'a, T> DoubleEndedIterator for Chunks<'a, T> {
    #[inline]
    fn next_back(&mut self) -> Option<&'a [T]> {
        if self.v.is_empty() {
            None
        } else {
            let remainder = self.v.len() % self.chunk_size;
            let chunksz = if remainder != 0 { remainder } else { self.chunk_size };
            let (fst, snd) = unsafe { self.v.split_at_unchecked(self.v.len() - chunksz) };
            self.v = fst;
            Some(snd)
        }
    }
    #[inline]
    fn nth_back(&mut self, n: usize) -> Option<Self::Item> {
        let len = self.len();
        if n >= len {
            self.v = &[];
            None
        } else {
            let start = (len - 1 - n) * self.chunk_size;
            let end = match start.checked_add(self.chunk_size) {
                Some(res) => cmp::min(self.v.len(), res),
                None => self.v.len(),
            };
            let nth_back = &self.v[start..end];
            self.v = &self.v[..start];
            Some(nth_back)
        }
    }
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<T> ExactSizeIterator for Chunks<'_, T> {}
#[unstable(feature = "trusted_len", issue = "37572")]
unsafe impl<T> TrustedLen for Chunks<'_, T> {}
#[stable(feature = "fused", since = "1.26.0")]
impl<T> FusedIterator for Chunks<'_, T> {}
#[doc(hidden)]
#[unstable(feature = "trusted_random_access", issue = "none")]
unsafe impl<'a, T> TrustedRandomAccess for Chunks<'a, T> {}
#[doc(hidden)]
#[unstable(feature = "trusted_random_access", issue = "none")]
unsafe impl<'a, T> TrustedRandomAccessNoCoerce for Chunks<'a, T> {
    const MAY_HAVE_SIDE_EFFECT: bool = false;
}
#[derive(Debug)]
#[stable(feature = "rust1", since = "1.0.0")]
#[must_use = "iterators are lazy and do nothing unless consumed"]
pub struct ChunksMut<'a, T: 'a> {
    v: *mut [T],
    chunk_size: usize,
    _marker: PhantomData<&'a mut T>,
}
impl<'a, T: 'a> ChunksMut<'a, T> {
    #[inline]
    pub(super) fn new(slice: &'a mut [T], size: usize) -> Self {
        Self { v: slice, chunk_size: size, _marker: PhantomData }
    }
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<'a, T> Iterator for ChunksMut<'a, T> {
    type Item = &'a mut [T];
    #[inline]
    fn next(&mut self) -> Option<&'a mut [T]> {
        if self.v.is_empty() {
            None
        } else {
            let sz = cmp::min(self.v.len(), self.chunk_size);
            let (head, tail) = unsafe { self.v.split_at_mut(sz) };
            self.v = tail;
            Some(unsafe { &mut *head })
        }
    }
    #[inline]
    fn size_hint(&self) -> (usize, Option<usize>) {
        if self.v.is_empty() {
            (0, Some(0))
        } else {
            let n = self.v.len() / self.chunk_size;
            let rem = self.v.len() % self.chunk_size;
            let n = if rem > 0 { n + 1 } else { n };
            (n, Some(n))
        }
    }
    #[inline]
    fn count(self) -> usize {
        self.len()
    }
    #[inline]
    fn nth(&mut self, n: usize) -> Option<&'a mut [T]> {
        let (start, overflow) = n.overflowing_mul(self.chunk_size);
        if start >= self.v.len() || overflow {
            self.v = &mut [];
            None
        } else {
            let end = match start.checked_add(self.chunk_size) {
                Some(sum) => cmp::min(self.v.len(), sum),
                None => self.v.len(),
            };
            let (head, tail) = unsafe { self.v.split_at_mut(end) };
            let (_, nth) = unsafe { head.split_at_mut(start) };
            self.v = tail;
            Some(unsafe { &mut *nth })
        }
    }
    #[inline]
    fn last(self) -> Option<Self::Item> {
        if self.v.is_empty() {
            None
        } else {
            let start = (self.v.len() - 1) / self.chunk_size * self.chunk_size;
            Some(unsafe { &mut *self.v.get_unchecked_mut(start..) })
        }
    }
    unsafe fn __iterator_get_unchecked(&mut self, idx: usize) -> Self::Item {
        let start = idx * self.chunk_size;
        unsafe {
            let len = cmp::min(self.v.len().unchecked_sub(start), self.chunk_size);
            from_raw_parts_mut(self.v.as_mut_ptr().add(start), len)
        }
    }
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<'a, T> DoubleEndedIterator for ChunksMut<'a, T> {
    #[inline]
    fn next_back(&mut self) -> Option<&'a mut [T]> {
        if self.v.is_empty() {
            None
        } else {
            let remainder = self.v.len() % self.chunk_size;
            let sz = if remainder != 0 { remainder } else { self.chunk_size };
            let len = self.v.len();
            let (head, tail) = unsafe { self.v.split_at_mut_unchecked(len - sz) };
            self.v = head;
            Some(unsafe { &mut *tail })
        }
    }
    #[inline]
    fn nth_back(&mut self, n: usize) -> Option<Self::Item> {
        let len = self.len();
        if n >= len {
            self.v = &mut [];
            None
        } else {
            let start = (len - 1 - n) * self.chunk_size;
            let end = match start.checked_add(self.chunk_size) {
                Some(res) => cmp::min(self.v.len(), res),
                None => self.v.len(),
            };
            let (temp, _tail) = unsafe { self.v.split_at_mut(end) };
            let (head, nth_back) = unsafe { temp.split_at_mut(start) };
            self.v = head;
            Some(unsafe { &mut *nth_back })
        }
    }
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<T> ExactSizeIterator for ChunksMut<'_, T> {}
#[unstable(feature = "trusted_len", issue = "37572")]
unsafe impl<T> TrustedLen for ChunksMut<'_, T> {}
#[stable(feature = "fused", since = "1.26.0")]
impl<T> FusedIterator for ChunksMut<'_, T> {}
#[doc(hidden)]
#[unstable(feature = "trusted_random_access", issue = "none")]
unsafe impl<'a, T> TrustedRandomAccess for ChunksMut<'a, T> {}
#[doc(hidden)]
#[unstable(feature = "trusted_random_access", issue = "none")]
unsafe impl<'a, T> TrustedRandomAccessNoCoerce for ChunksMut<'a, T> {
    const MAY_HAVE_SIDE_EFFECT: bool = false;
}
#[stable(feature = "rust1", since = "1.0.0")]
unsafe impl<T> Send for ChunksMut<'_, T> where T: Send {}
#[stable(feature = "rust1", since = "1.0.0")]
unsafe impl<T> Sync for ChunksMut<'_, T> where T: Sync {}
#[derive(Debug)]
#[stable(feature = "chunks_exact", since = "1.31.0")]
#[must_use = "iterators are lazy and do nothing unless consumed"]
pub struct ChunksExact<'a, T: 'a> {
    v: &'a [T],
    rem: &'a [T],
    chunk_size: usize,
}
impl<'a, T> ChunksExact<'a, T> {
    #[inline]
    pub(super) fn new(slice: &'a [T], chunk_size: usize) -> Self {
        let rem = slice.len() % chunk_size;
        let fst_len = slice.len() - rem;
        let (fst, snd) = unsafe { slice.split_at_unchecked(fst_len) };
        Self { v: fst, rem: snd, chunk_size }
    }
    #[must_use]
    #[stable(feature = "chunks_exact", since = "1.31.0")]
    pub fn remainder(&self) -> &'a [T] {
        self.rem
    }
}
#[stable(feature = "chunks_exact", since = "1.31.0")]
impl<T> Clone for ChunksExact<'_, T> {
    fn clone(&self) -> Self {
        ChunksExact { v: self.v, rem: self.rem, chunk_size: self.chunk_size }
    }
}
#[stable(feature = "chunks_exact", since = "1.31.0")]
impl<'a, T> Iterator for ChunksExact<'a, T> {
    type Item = &'a [T];
    #[inline]
    fn next(&mut self) -> Option<&'a [T]> {
        if self.v.len() < self.chunk_size {
            None
        } else {
            let (fst, snd) = self.v.split_at(self.chunk_size);
            self.v = snd;
            Some(fst)
        }
    }
    #[inline]
    fn size_hint(&self) -> (usize, Option<usize>) {
        let n = self.v.len() / self.chunk_size;
        (n, Some(n))
    }
    #[inline]
    fn count(self) -> usize {
        self.len()
    }
    #[inline]
    fn nth(&mut self, n: usize) -> Option<Self::Item> {
        let (start, overflow) = n.overflowing_mul(self.chunk_size);
        if start >= self.v.len() || overflow {
            self.v = &[];
            None
        } else {
            let (_, snd) = self.v.split_at(start);
            self.v = snd;
            self.next()
        }
    }
    #[inline]
    fn last(mut self) -> Option<Self::Item> {
        self.next_back()
    }
    unsafe fn __iterator_get_unchecked(&mut self, idx: usize) -> Self::Item {
        let start = idx * self.chunk_size;
        unsafe { from_raw_parts(self.v.as_ptr().add(start), self.chunk_size) }
    }
}
#[stable(feature = "chunks_exact", since = "1.31.0")]
impl<'a, T> DoubleEndedIterator for ChunksExact<'a, T> {
    #[inline]
    fn next_back(&mut self) -> Option<&'a [T]> {
        if self.v.len() < self.chunk_size {
            None
        } else {
            let (fst, snd) = self.v.split_at(self.v.len() - self.chunk_size);
            self.v = fst;
            Some(snd)
        }
    }
    #[inline]
    fn nth_back(&mut self, n: usize) -> Option<Self::Item> {
        let len = self.len();
        if n >= len {
            self.v = &[];
            None
        } else {
            let start = (len - 1 - n) * self.chunk_size;
            let end = start + self.chunk_size;
            let nth_back = &self.v[start..end];
            self.v = &self.v[..start];
            Some(nth_back)
        }
    }
}
#[stable(feature = "chunks_exact", since = "1.31.0")]
impl<T> ExactSizeIterator for ChunksExact<'_, T> {
    fn is_empty(&self) -> bool {
        self.v.is_empty()
    }
}
#[unstable(feature = "trusted_len", issue = "37572")]
unsafe impl<T> TrustedLen for ChunksExact<'_, T> {}
#[stable(feature = "chunks_exact", since = "1.31.0")]
impl<T> FusedIterator for ChunksExact<'_, T> {}
#[doc(hidden)]
#[unstable(feature = "trusted_random_access", issue = "none")]
unsafe impl<'a, T> TrustedRandomAccess for ChunksExact<'a, T> {}
#[doc(hidden)]
#[unstable(feature = "trusted_random_access", issue = "none")]
unsafe impl<'a, T> TrustedRandomAccessNoCoerce for ChunksExact<'a, T> {
    const MAY_HAVE_SIDE_EFFECT: bool = false;
}
#[derive(Debug)]
#[stable(feature = "chunks_exact", since = "1.31.0")]
#[must_use = "iterators are lazy and do nothing unless consumed"]
pub struct ChunksExactMut<'a, T: 'a> {
    v: *mut [T],
    rem: &'a mut [T], chunk_size: usize,
    _marker: PhantomData<&'a mut T>,
}
impl<'a, T> ChunksExactMut<'a, T> {
    #[inline]
    pub(super) fn new(slice: &'a mut [T], chunk_size: usize) -> Self {
        let rem = slice.len() % chunk_size;
        let fst_len = slice.len() - rem;
        let (fst, snd) = unsafe { slice.split_at_mut_unchecked(fst_len) };
        Self { v: fst, rem: snd, chunk_size, _marker: PhantomData }
    }
    #[must_use = "`self` will be dropped if the result is not used"]
    #[stable(feature = "chunks_exact", since = "1.31.0")]
    pub fn into_remainder(self) -> &'a mut [T] {
        self.rem
    }
}
#[stable(feature = "chunks_exact", since = "1.31.0")]
impl<'a, T> Iterator for ChunksExactMut<'a, T> {
    type Item = &'a mut [T];
    #[inline]
    fn next(&mut self) -> Option<&'a mut [T]> {
        if self.v.len() < self.chunk_size {
            None
        } else {
            let (head, tail) = unsafe { self.v.split_at_mut(self.chunk_size) };
            self.v = tail;
            Some(unsafe { &mut *head })
        }
    }
    #[inline]
    fn size_hint(&self) -> (usize, Option<usize>) {
        let n = self.v.len() / self.chunk_size;
        (n, Some(n))
    }
    #[inline]
    fn count(self) -> usize {
        self.len()
    }
    #[inline]
    fn nth(&mut self, n: usize) -> Option<&'a mut [T]> {
        let (start, overflow) = n.overflowing_mul(self.chunk_size);
        if start >= self.v.len() || overflow {
            self.v = &mut [];
            None
        } else {
            let (_, snd) = unsafe { self.v.split_at_mut(start) };
            self.v = snd;
            self.next()
        }
    }
    #[inline]
    fn last(mut self) -> Option<Self::Item> {
        self.next_back()
    }
    unsafe fn __iterator_get_unchecked(&mut self, idx: usize) -> Self::Item {
        let start = idx * self.chunk_size;
        unsafe { from_raw_parts_mut(self.v.as_mut_ptr().add(start), self.chunk_size) }
    }
}
#[stable(feature = "chunks_exact", since = "1.31.0")]
impl<'a, T> DoubleEndedIterator for ChunksExactMut<'a, T> {
    #[inline]
    fn next_back(&mut self) -> Option<&'a mut [T]> {
        if self.v.len() < self.chunk_size {
            None
        } else {
            let (head, tail) = unsafe { self.v.split_at_mut(self.v.len() - self.chunk_size) };
            self.v = head;
            Some(unsafe { &mut *tail })
        }
    }
    #[inline]
    fn nth_back(&mut self, n: usize) -> Option<Self::Item> {
        let len = self.len();
        if n >= len {
            self.v = &mut [];
            None
        } else {
            let start = (len - 1 - n) * self.chunk_size;
            let end = start + self.chunk_size;
            let (temp, _tail) = unsafe { mem::replace(&mut self.v, &mut []).split_at_mut(end) };
            let (head, nth_back) = unsafe { temp.split_at_mut(start) };
            self.v = head;
            Some(unsafe { &mut *nth_back })
        }
    }
}
#[stable(feature = "chunks_exact", since = "1.31.0")]
impl<T> ExactSizeIterator for ChunksExactMut<'_, T> {
    fn is_empty(&self) -> bool {
        self.v.is_empty()
    }
}
#[unstable(feature = "trusted_len", issue = "37572")]
unsafe impl<T> TrustedLen for ChunksExactMut<'_, T> {}
#[stable(feature = "chunks_exact", since = "1.31.0")]
impl<T> FusedIterator for ChunksExactMut<'_, T> {}
#[doc(hidden)]
#[unstable(feature = "trusted_random_access", issue = "none")]
unsafe impl<'a, T> TrustedRandomAccess for ChunksExactMut<'a, T> {}
#[doc(hidden)]
#[unstable(feature = "trusted_random_access", issue = "none")]
unsafe impl<'a, T> TrustedRandomAccessNoCoerce for ChunksExactMut<'a, T> {
    const MAY_HAVE_SIDE_EFFECT: bool = false;
}
#[stable(feature = "chunks_exact", since = "1.31.0")]
unsafe impl<T> Send for ChunksExactMut<'_, T> where T: Send {}
#[stable(feature = "chunks_exact", since = "1.31.0")]
unsafe impl<T> Sync for ChunksExactMut<'_, T> where T: Sync {}
#[derive(Debug, Clone, Copy)]
#[unstable(feature = "array_windows", issue = "75027")]
#[must_use = "iterators are lazy and do nothing unless consumed"]
pub struct ArrayWindows<'a, T: 'a, const N: usize> {
    slice_head: *const T,
    num: usize,
    marker: PhantomData<&'a [T; N]>,
}
impl<'a, T: 'a, const N: usize> ArrayWindows<'a, T, N> {
    #[inline]
    pub(super) fn new(slice: &'a [T]) -> Self {
        let num_windows = slice.len().saturating_sub(N - 1);
        Self { slice_head: slice.as_ptr(), num: num_windows, marker: PhantomData }
    }
}
#[unstable(feature = "array_windows", issue = "75027")]
impl<'a, T, const N: usize> Iterator for ArrayWindows<'a, T, N> {
    type Item = &'a [T; N];
    #[inline]
    fn next(&mut self) -> Option<Self::Item> {
        if self.num == 0 {
            return None;
        }
        let ret = unsafe { &*self.slice_head.cast::<[T; N]>() };
        self.slice_head = unsafe { self.slice_head.add(1) };
        self.num -= 1;
        Some(ret)
    }
    #[inline]
    fn size_hint(&self) -> (usize, Option<usize>) {
        (self.num, Some(self.num))
    }
    #[inline]
    fn count(self) -> usize {
        self.num
    }
    #[inline]
    fn nth(&mut self, n: usize) -> Option<Self::Item> {
        if self.num <= n {
            self.num = 0;
            return None;
        }
        let ret = unsafe { &*self.slice_head.add(n).cast::<[T; N]>() };
        self.slice_head = unsafe { self.slice_head.add(n + 1) };
        self.num -= n + 1;
        Some(ret)
    }
    #[inline]
    fn last(mut self) -> Option<Self::Item> {
        self.nth(self.num.checked_sub(1)?)
    }
}
#[unstable(feature = "array_windows", issue = "75027")]
impl<'a, T, const N: usize> DoubleEndedIterator for ArrayWindows<'a, T, N> {
    #[inline]
    fn next_back(&mut self) -> Option<&'a [T; N]> {
        if self.num == 0 {
            return None;
        }
        let ret = unsafe { &*self.slice_head.add(self.num - 1).cast::<[T; N]>() };
        self.num -= 1;
        Some(ret)
    }
    #[inline]
    fn nth_back(&mut self, n: usize) -> Option<&'a [T; N]> {
        if self.num <= n {
            self.num = 0;
            return None;
        }
        let ret = unsafe { &*self.slice_head.add(self.num - (n + 1)).cast::<[T; N]>() };
        self.num -= n + 1;
        Some(ret)
    }
}
#[unstable(feature = "array_windows", issue = "75027")]
impl<T, const N: usize> ExactSizeIterator for ArrayWindows<'_, T, N> {
    fn is_empty(&self) -> bool {
        self.num == 0
    }
}
#[derive(Debug)]
#[unstable(feature = "array_chunks", issue = "74985")]
#[must_use = "iterators are lazy and do nothing unless consumed"]
pub struct ArrayChunks<'a, T: 'a, const N: usize> {
    iter: Iter<'a, [T; N]>,
    rem: &'a [T],
}
impl<'a, T, const N: usize> ArrayChunks<'a, T, N> {
    #[inline]
    pub(super) fn new(slice: &'a [T]) -> Self {
        let (array_slice, rem) = slice.as_chunks();
        Self { iter: array_slice.iter(), rem }
    }
    #[must_use]
    #[unstable(feature = "array_chunks", issue = "74985")]
    pub fn remainder(&self) -> &'a [T] {
        self.rem
    }
}
#[unstable(feature = "array_chunks", issue = "74985")]
impl<T, const N: usize> Clone for ArrayChunks<'_, T, N> {
    fn clone(&self) -> Self {
        ArrayChunks { iter: self.iter.clone(), rem: self.rem }
    }
}
#[unstable(feature = "array_chunks", issue = "74985")]
impl<'a, T, const N: usize> Iterator for ArrayChunks<'a, T, N> {
    type Item = &'a [T; N];
    #[inline]
    fn next(&mut self) -> Option<&'a [T; N]> {
        self.iter.next()
    }
    #[inline]
    fn size_hint(&self) -> (usize, Option<usize>) {
        self.iter.size_hint()
    }
    #[inline]
    fn count(self) -> usize {
        self.iter.count()
    }
    #[inline]
    fn nth(&mut self, n: usize) -> Option<Self::Item> {
        self.iter.nth(n)
    }
    #[inline]
    fn last(self) -> Option<Self::Item> {
        self.iter.last()
    }
    unsafe fn __iterator_get_unchecked(&mut self, i: usize) -> &'a [T; N] {
        unsafe { self.iter.__iterator_get_unchecked(i) }
    }
}
#[unstable(feature = "array_chunks", issue = "74985")]
impl<'a, T, const N: usize> DoubleEndedIterator for ArrayChunks<'a, T, N> {
    #[inline]
    fn next_back(&mut self) -> Option<&'a [T; N]> {
        self.iter.next_back()
    }
    #[inline]
    fn nth_back(&mut self, n: usize) -> Option<Self::Item> {
        self.iter.nth_back(n)
    }
}
#[unstable(feature = "array_chunks", issue = "74985")]
impl<T, const N: usize> ExactSizeIterator for ArrayChunks<'_, T, N> {
    fn is_empty(&self) -> bool {
        self.iter.is_empty()
    }
}
#[unstable(feature = "trusted_len", issue = "37572")]
unsafe impl<T, const N: usize> TrustedLen for ArrayChunks<'_, T, N> {}
#[unstable(feature = "array_chunks", issue = "74985")]
impl<T, const N: usize> FusedIterator for ArrayChunks<'_, T, N> {}
#[doc(hidden)]
#[unstable(feature = "array_chunks", issue = "74985")]
unsafe impl<'a, T, const N: usize> TrustedRandomAccess for ArrayChunks<'a, T, N> {}
#[doc(hidden)]
#[unstable(feature = "array_chunks", issue = "74985")]
unsafe impl<'a, T, const N: usize> TrustedRandomAccessNoCoerce for ArrayChunks<'a, T, N> {
    const MAY_HAVE_SIDE_EFFECT: bool = false;
}
#[derive(Debug)]
#[unstable(feature = "array_chunks", issue = "74985")]
#[must_use = "iterators are lazy and do nothing unless consumed"]
pub struct ArrayChunksMut<'a, T: 'a, const N: usize> {
    iter: IterMut<'a, [T; N]>,
    rem: &'a mut [T],
}
impl<'a, T, const N: usize> ArrayChunksMut<'a, T, N> {
    #[inline]
    pub(super) fn new(slice: &'a mut [T]) -> Self {
        let (array_slice, rem) = slice.as_chunks_mut();
        Self { iter: array_slice.iter_mut(), rem }
    }
    #[must_use = "`self` will be dropped if the result is not used"]
    #[unstable(feature = "array_chunks", issue = "74985")]
    pub fn into_remainder(self) -> &'a mut [T] {
        self.rem
    }
}
#[unstable(feature = "array_chunks", issue = "74985")]
impl<'a, T, const N: usize> Iterator for ArrayChunksMut<'a, T, N> {
    type Item = &'a mut [T; N];
    #[inline]
    fn next(&mut self) -> Option<&'a mut [T; N]> {
        self.iter.next()
    }
    #[inline]
    fn size_hint(&self) -> (usize, Option<usize>) {
        self.iter.size_hint()
    }
    #[inline]
    fn count(self) -> usize {
        self.iter.count()
    }
    #[inline]
    fn nth(&mut self, n: usize) -> Option<Self::Item> {
        self.iter.nth(n)
    }
    #[inline]
    fn last(self) -> Option<Self::Item> {
        self.iter.last()
    }
    unsafe fn __iterator_get_unchecked(&mut self, i: usize) -> &'a mut [T; N] {
        unsafe { self.iter.__iterator_get_unchecked(i) }
    }
}
#[unstable(feature = "array_chunks", issue = "74985")]
impl<'a, T, const N: usize> DoubleEndedIterator for ArrayChunksMut<'a, T, N> {
    #[inline]
    fn next_back(&mut self) -> Option<&'a mut [T; N]> {
        self.iter.next_back()
    }
    #[inline]
    fn nth_back(&mut self, n: usize) -> Option<Self::Item> {
        self.iter.nth_back(n)
    }
}
#[unstable(feature = "array_chunks", issue = "74985")]
impl<T, const N: usize> ExactSizeIterator for ArrayChunksMut<'_, T, N> {
    fn is_empty(&self) -> bool {
        self.iter.is_empty()
    }
}
#[unstable(feature = "trusted_len", issue = "37572")]
unsafe impl<T, const N: usize> TrustedLen for ArrayChunksMut<'_, T, N> {}
#[unstable(feature = "array_chunks", issue = "74985")]
impl<T, const N: usize> FusedIterator for ArrayChunksMut<'_, T, N> {}
#[doc(hidden)]
#[unstable(feature = "array_chunks", issue = "74985")]
unsafe impl<'a, T, const N: usize> TrustedRandomAccess for ArrayChunksMut<'a, T, N> {}
#[doc(hidden)]
#[unstable(feature = "array_chunks", issue = "74985")]
unsafe impl<'a, T, const N: usize> TrustedRandomAccessNoCoerce for ArrayChunksMut<'a, T, N> {
    const MAY_HAVE_SIDE_EFFECT: bool = false;
}
#[derive(Debug)]
#[stable(feature = "rchunks", since = "1.31.0")]
#[must_use = "iterators are lazy and do nothing unless consumed"]
pub struct RChunks<'a, T: 'a> {
    v: &'a [T],
    chunk_size: usize,
}
impl<'a, T: 'a> RChunks<'a, T> {
    #[inline]
    pub(super) fn new(slice: &'a [T], size: usize) -> Self {
        Self { v: slice, chunk_size: size }
    }
}
#[stable(feature = "rchunks", since = "1.31.0")]
impl<T> Clone for RChunks<'_, T> {
    fn clone(&self) -> Self {
        RChunks { v: self.v, chunk_size: self.chunk_size }
    }
}
#[stable(feature = "rchunks", since = "1.31.0")]
impl<'a, T> Iterator for RChunks<'a, T> {
    type Item = &'a [T];
    #[inline]
    fn next(&mut self) -> Option<&'a [T]> {
        if self.v.is_empty() {
            None
        } else {
            let len = self.v.len();
            let chunksz = cmp::min(len, self.chunk_size);
            let (fst, snd) = unsafe { self.v.split_at_unchecked(len - chunksz) };
            self.v = fst;
            Some(snd)
        }
    }
    #[inline]
    fn size_hint(&self) -> (usize, Option<usize>) {
        if self.v.is_empty() {
            (0, Some(0))
        } else {
            let n = self.v.len() / self.chunk_size;
            let rem = self.v.len() % self.chunk_size;
            let n = if rem > 0 { n + 1 } else { n };
            (n, Some(n))
        }
    }
    #[inline]
    fn count(self) -> usize {
        self.len()
    }
    #[inline]
    fn nth(&mut self, n: usize) -> Option<Self::Item> {
        let (end, overflow) = n.overflowing_mul(self.chunk_size);
        if end >= self.v.len() || overflow {
            self.v = &[];
            None
        } else {
            let end = self.v.len() - end;
            let start = match end.checked_sub(self.chunk_size) {
                Some(sum) => sum,
                None => 0,
            };
            let nth = &self.v[start..end];
            self.v = &self.v[0..start];
            Some(nth)
        }
    }
    #[inline]
    fn last(self) -> Option<Self::Item> {
        if self.v.is_empty() {
            None
        } else {
            let rem = self.v.len() % self.chunk_size;
            let end = if rem == 0 { self.chunk_size } else { rem };
            Some(&self.v[0..end])
        }
    }
    unsafe fn __iterator_get_unchecked(&mut self, idx: usize) -> Self::Item {
        let end = self.v.len() - idx * self.chunk_size;
        let start = match end.checked_sub(self.chunk_size) {
            None => 0,
            Some(start) => start,
        };
        unsafe { from_raw_parts(self.v.as_ptr().add(start), end - start) }
    }
}
#[stable(feature = "rchunks", since = "1.31.0")]
impl<'a, T> DoubleEndedIterator for RChunks<'a, T> {
    #[inline]
    fn next_back(&mut self) -> Option<&'a [T]> {
        if self.v.is_empty() {
            None
        } else {
            let remainder = self.v.len() % self.chunk_size;
            let chunksz = if remainder != 0 { remainder } else { self.chunk_size };
            let (fst, snd) = unsafe { self.v.split_at_unchecked(chunksz) };
            self.v = snd;
            Some(fst)
        }
    }
    #[inline]
    fn nth_back(&mut self, n: usize) -> Option<Self::Item> {
        let len = self.len();
        if n >= len {
            self.v = &[];
            None
        } else {
            let offset_from_end = (len - 1 - n) * self.chunk_size;
            let end = self.v.len() - offset_from_end;
            let start = end.saturating_sub(self.chunk_size);
            let nth_back = &self.v[start..end];
            self.v = &self.v[end..];
            Some(nth_back)
        }
    }
}
#[stable(feature = "rchunks", since = "1.31.0")]
impl<T> ExactSizeIterator for RChunks<'_, T> {}
#[unstable(feature = "trusted_len", issue = "37572")]
unsafe impl<T> TrustedLen for RChunks<'_, T> {}
#[stable(feature = "rchunks", since = "1.31.0")]
impl<T> FusedIterator for RChunks<'_, T> {}
#[doc(hidden)]
#[unstable(feature = "trusted_random_access", issue = "none")]
unsafe impl<'a, T> TrustedRandomAccess for RChunks<'a, T> {}
#[doc(hidden)]
#[unstable(feature = "trusted_random_access", issue = "none")]
unsafe impl<'a, T> TrustedRandomAccessNoCoerce for RChunks<'a, T> {
    const MAY_HAVE_SIDE_EFFECT: bool = false;
}
#[derive(Debug)]
#[stable(feature = "rchunks", since = "1.31.0")]
#[must_use = "iterators are lazy and do nothing unless consumed"]
pub struct RChunksMut<'a, T: 'a> {
    v: *mut [T],
    chunk_size: usize,
    _marker: PhantomData<&'a mut T>,
}
impl<'a, T: 'a> RChunksMut<'a, T> {
    #[inline]
    pub(super) fn new(slice: &'a mut [T], size: usize) -> Self {
        Self { v: slice, chunk_size: size, _marker: PhantomData }
    }
}
#[stable(feature = "rchunks", since = "1.31.0")]
impl<'a, T> Iterator for RChunksMut<'a, T> {
    type Item = &'a mut [T];
    #[inline]
    fn next(&mut self) -> Option<&'a mut [T]> {
        if self.v.is_empty() {
            None
        } else {
            let sz = cmp::min(self.v.len(), self.chunk_size);
            let len = self.v.len();
            let (head, tail) = unsafe { self.v.split_at_mut_unchecked(len - sz) };
            self.v = head;
            Some(unsafe { &mut *tail })
        }
    }
    #[inline]
    fn size_hint(&self) -> (usize, Option<usize>) {
        if self.v.is_empty() {
            (0, Some(0))
        } else {
            let n = self.v.len() / self.chunk_size;
            let rem = self.v.len() % self.chunk_size;
            let n = if rem > 0 { n + 1 } else { n };
            (n, Some(n))
        }
    }
    #[inline]
    fn count(self) -> usize {
        self.len()
    }
    #[inline]
    fn nth(&mut self, n: usize) -> Option<&'a mut [T]> {
        let (end, overflow) = n.overflowing_mul(self.chunk_size);
        if end >= self.v.len() || overflow {
            self.v = &mut [];
            None
        } else {
            let end = self.v.len() - end;
            let start = match end.checked_sub(self.chunk_size) {
                Some(sum) => sum,
                None => 0,
            };
            let (head, tail) = unsafe { self.v.split_at_mut(start) };
            let (nth, _) = unsafe { tail.split_at_mut(end - start) };
            self.v = head;
            Some(unsafe { &mut *nth })
        }
    }
    #[inline]
    fn last(self) -> Option<Self::Item> {
        if self.v.is_empty() {
            None
        } else {
            let rem = self.v.len() % self.chunk_size;
            let end = if rem == 0 { self.chunk_size } else { rem };
            Some(unsafe { &mut *self.v.get_unchecked_mut(0..end) })
        }
    }
    unsafe fn __iterator_get_unchecked(&mut self, idx: usize) -> Self::Item {
        let end = self.v.len() - idx * self.chunk_size;
        let start = match end.checked_sub(self.chunk_size) {
            None => 0,
            Some(start) => start,
        };
        unsafe { from_raw_parts_mut(self.v.as_mut_ptr().add(start), end - start) }
    }
}
#[stable(feature = "rchunks", since = "1.31.0")]
impl<'a, T> DoubleEndedIterator for RChunksMut<'a, T> {
    #[inline]
    fn next_back(&mut self) -> Option<&'a mut [T]> {
        if self.v.is_empty() {
            None
        } else {
            let remainder = self.v.len() % self.chunk_size;
            let sz = if remainder != 0 { remainder } else { self.chunk_size };
            let (head, tail) = unsafe { self.v.split_at_mut_unchecked(sz) };
            self.v = tail;
            Some(unsafe { &mut *head })
        }
    }
    #[inline]
    fn nth_back(&mut self, n: usize) -> Option<Self::Item> {
        let len = self.len();
        if n >= len {
            self.v = &mut [];
            None
        } else {
            let offset_from_end = (len - 1 - n) * self.chunk_size;
            let end = self.v.len() - offset_from_end;
            let start = end.saturating_sub(self.chunk_size);
            let (tmp, tail) = unsafe { self.v.split_at_mut(end) };
            let (_, nth_back) = unsafe { tmp.split_at_mut(start) };
            self.v = tail;
            Some(unsafe { &mut *nth_back })
        }
    }
}
#[stable(feature = "rchunks", since = "1.31.0")]
impl<T> ExactSizeIterator for RChunksMut<'_, T> {}
#[unstable(feature = "trusted_len", issue = "37572")]
unsafe impl<T> TrustedLen for RChunksMut<'_, T> {}
#[stable(feature = "rchunks", since = "1.31.0")]
impl<T> FusedIterator for RChunksMut<'_, T> {}
#[doc(hidden)]
#[unstable(feature = "trusted_random_access", issue = "none")]
unsafe impl<'a, T> TrustedRandomAccess for RChunksMut<'a, T> {}
#[doc(hidden)]
#[unstable(feature = "trusted_random_access", issue = "none")]
unsafe impl<'a, T> TrustedRandomAccessNoCoerce for RChunksMut<'a, T> {
    const MAY_HAVE_SIDE_EFFECT: bool = false;
}
#[stable(feature = "rchunks", since = "1.31.0")]
unsafe impl<T> Send for RChunksMut<'_, T> where T: Send {}
#[stable(feature = "rchunks", since = "1.31.0")]
unsafe impl<T> Sync for RChunksMut<'_, T> where T: Sync {}
#[derive(Debug)]
#[stable(feature = "rchunks", since = "1.31.0")]
#[must_use = "iterators are lazy and do nothing unless consumed"]
pub struct RChunksExact<'a, T: 'a> {
    v: &'a [T],
    rem: &'a [T],
    chunk_size: usize,
}
impl<'a, T> RChunksExact<'a, T> {
    #[inline]
    pub(super) fn new(slice: &'a [T], chunk_size: usize) -> Self {
        let rem = slice.len() % chunk_size;
        let (fst, snd) = unsafe { slice.split_at_unchecked(rem) };
        Self { v: snd, rem: fst, chunk_size }
    }
    #[must_use]
    #[stable(feature = "rchunks", since = "1.31.0")]
    pub fn remainder(&self) -> &'a [T] {
        self.rem
    }
}
#[stable(feature = "rchunks", since = "1.31.0")]
impl<'a, T> Clone for RChunksExact<'a, T> {
    fn clone(&self) -> RChunksExact<'a, T> {
        RChunksExact { v: self.v, rem: self.rem, chunk_size: self.chunk_size }
    }
}
#[stable(feature = "rchunks", since = "1.31.0")]
impl<'a, T> Iterator for RChunksExact<'a, T> {
    type Item = &'a [T];
    #[inline]
    fn next(&mut self) -> Option<&'a [T]> {
        if self.v.len() < self.chunk_size {
            None
        } else {
            let (fst, snd) = self.v.split_at(self.v.len() - self.chunk_size);
            self.v = fst;
            Some(snd)
        }
    }
    #[inline]
    fn size_hint(&self) -> (usize, Option<usize>) {
        let n = self.v.len() / self.chunk_size;
        (n, Some(n))
    }
    #[inline]
    fn count(self) -> usize {
        self.len()
    }
    #[inline]
    fn nth(&mut self, n: usize) -> Option<Self::Item> {
        let (end, overflow) = n.overflowing_mul(self.chunk_size);
        if end >= self.v.len() || overflow {
            self.v = &[];
            None
        } else {
            let (fst, _) = self.v.split_at(self.v.len() - end);
            self.v = fst;
            self.next()
        }
    }
    #[inline]
    fn last(mut self) -> Option<Self::Item> {
        self.next_back()
    }
    unsafe fn __iterator_get_unchecked(&mut self, idx: usize) -> Self::Item {
        let end = self.v.len() - idx * self.chunk_size;
        let start = end - self.chunk_size;
        unsafe { from_raw_parts(self.v.as_ptr().add(start), self.chunk_size) }
    }
}
#[stable(feature = "rchunks", since = "1.31.0")]
impl<'a, T> DoubleEndedIterator for RChunksExact<'a, T> {
    #[inline]
    fn next_back(&mut self) -> Option<&'a [T]> {
        if self.v.len() < self.chunk_size {
            None
        } else {
            let (fst, snd) = self.v.split_at(self.chunk_size);
            self.v = snd;
            Some(fst)
        }
    }
    #[inline]
    fn nth_back(&mut self, n: usize) -> Option<Self::Item> {
        let len = self.len();
        if n >= len {
            self.v = &[];
            None
        } else {
            let offset = (len - n) * self.chunk_size;
            let start = self.v.len() - offset;
            let end = start + self.chunk_size;
            let nth_back = &self.v[start..end];
            self.v = &self.v[end..];
            Some(nth_back)
        }
    }
}
#[stable(feature = "rchunks", since = "1.31.0")]
impl<'a, T> ExactSizeIterator for RChunksExact<'a, T> {
    fn is_empty(&self) -> bool {
        self.v.is_empty()
    }
}
#[unstable(feature = "trusted_len", issue = "37572")]
unsafe impl<T> TrustedLen for RChunksExact<'_, T> {}
#[stable(feature = "rchunks", since = "1.31.0")]
impl<T> FusedIterator for RChunksExact<'_, T> {}
#[doc(hidden)]
#[unstable(feature = "trusted_random_access", issue = "none")]
unsafe impl<'a, T> TrustedRandomAccess for RChunksExact<'a, T> {}
#[doc(hidden)]
#[unstable(feature = "trusted_random_access", issue = "none")]
unsafe impl<'a, T> TrustedRandomAccessNoCoerce for RChunksExact<'a, T> {
    const MAY_HAVE_SIDE_EFFECT: bool = false;
}
#[derive(Debug)]
#[stable(feature = "rchunks", since = "1.31.0")]
#[must_use = "iterators are lazy and do nothing unless consumed"]
pub struct RChunksExactMut<'a, T: 'a> {
    v: *mut [T],
    rem: &'a mut [T],
    chunk_size: usize,
}
impl<'a, T> RChunksExactMut<'a, T> {
    #[inline]
    pub(super) fn new(slice: &'a mut [T], chunk_size: usize) -> Self {
        let rem = slice.len() % chunk_size;
        let (fst, snd) = unsafe { slice.split_at_mut_unchecked(rem) };
        Self { v: snd, rem: fst, chunk_size }
    }
    #[must_use = "`self` will be dropped if the result is not used"]
    #[stable(feature = "rchunks", since = "1.31.0")]
    pub fn into_remainder(self) -> &'a mut [T] {
        self.rem
    }
}
#[stable(feature = "rchunks", since = "1.31.0")]
impl<'a, T> Iterator for RChunksExactMut<'a, T> {
    type Item = &'a mut [T];
    #[inline]
    fn next(&mut self) -> Option<&'a mut [T]> {
        if self.v.len() < self.chunk_size {
            None
        } else {
            let len = self.v.len();
            let (head, tail) = unsafe { self.v.split_at_mut(len - self.chunk_size) };
            self.v = head;
            Some(unsafe { &mut *tail })
        }
    }
    #[inline]
    fn size_hint(&self) -> (usize, Option<usize>) {
        let n = self.v.len() / self.chunk_size;
        (n, Some(n))
    }
    #[inline]
    fn count(self) -> usize {
        self.len()
    }
    #[inline]
    fn nth(&mut self, n: usize) -> Option<&'a mut [T]> {
        let (end, overflow) = n.overflowing_mul(self.chunk_size);
        if end >= self.v.len() || overflow {
            self.v = &mut [];
            None
        } else {
            let len = self.v.len();
            let (fst, _) = unsafe { self.v.split_at_mut(len - end) };
            self.v = fst;
            self.next()
        }
    }
    #[inline]
    fn last(mut self) -> Option<Self::Item> {
        self.next_back()
    }
    unsafe fn __iterator_get_unchecked(&mut self, idx: usize) -> Self::Item {
        let end = self.v.len() - idx * self.chunk_size;
        let start = end - self.chunk_size;
        unsafe { from_raw_parts_mut(self.v.as_mut_ptr().add(start), self.chunk_size) }
    }
}
#[stable(feature = "rchunks", since = "1.31.0")]
impl<'a, T> DoubleEndedIterator for RChunksExactMut<'a, T> {
    #[inline]
    fn next_back(&mut self) -> Option<&'a mut [T]> {
        if self.v.len() < self.chunk_size {
            None
        } else {
            let (head, tail) = unsafe { self.v.split_at_mut(self.chunk_size) };
            self.v = tail;
            Some(unsafe { &mut *head })
        }
    }
    #[inline]
    fn nth_back(&mut self, n: usize) -> Option<Self::Item> {
        let len = self.len();
        if n >= len {
            self.v = &mut [];
            None
        } else {
            let offset = (len - n) * self.chunk_size;
            let start = self.v.len() - offset;
            let end = start + self.chunk_size;
            let (tmp, tail) = unsafe { self.v.split_at_mut(end) };
            let (_, nth_back) = unsafe { tmp.split_at_mut(start) };
            self.v = tail;
            Some(unsafe { &mut *nth_back })
        }
    }
}
#[stable(feature = "rchunks", since = "1.31.0")]
impl<T> ExactSizeIterator for RChunksExactMut<'_, T> {
    fn is_empty(&self) -> bool {
        self.v.is_empty()
    }
}
#[unstable(feature = "trusted_len", issue = "37572")]
unsafe impl<T> TrustedLen for RChunksExactMut<'_, T> {}
#[stable(feature = "rchunks", since = "1.31.0")]
impl<T> FusedIterator for RChunksExactMut<'_, T> {}
#[doc(hidden)]
#[unstable(feature = "trusted_random_access", issue = "none")]
unsafe impl<'a, T> TrustedRandomAccess for RChunksExactMut<'a, T> {}
#[doc(hidden)]
#[unstable(feature = "trusted_random_access", issue = "none")]
unsafe impl<'a, T> TrustedRandomAccessNoCoerce for RChunksExactMut<'a, T> {
    const MAY_HAVE_SIDE_EFFECT: bool = false;
}
#[stable(feature = "rchunks", since = "1.31.0")]
unsafe impl<T> Send for RChunksExactMut<'_, T> where T: Send {}
#[stable(feature = "rchunks", since = "1.31.0")]
unsafe impl<T> Sync for RChunksExactMut<'_, T> where T: Sync {}
#[doc(hidden)]
#[unstable(feature = "trusted_random_access", issue = "none")]
unsafe impl<'a, T> TrustedRandomAccess for Iter<'a, T> {}
#[doc(hidden)]
#[unstable(feature = "trusted_random_access", issue = "none")]
unsafe impl<'a, T> TrustedRandomAccessNoCoerce for Iter<'a, T> {
    const MAY_HAVE_SIDE_EFFECT: bool = false;
}
#[doc(hidden)]
#[unstable(feature = "trusted_random_access", issue = "none")]
unsafe impl<'a, T> TrustedRandomAccess for IterMut<'a, T> {}
#[doc(hidden)]
#[unstable(feature = "trusted_random_access", issue = "none")]
unsafe impl<'a, T> TrustedRandomAccessNoCoerce for IterMut<'a, T> {
    const MAY_HAVE_SIDE_EFFECT: bool = false;
}
#[stable(feature = "slice_group_by", since = "1.77.0")]
#[must_use = "iterators are lazy and do nothing unless consumed"]
pub struct ChunkBy<'a, T: 'a, P> {
    slice: &'a [T],
    predicate: P,
}
#[stable(feature = "slice_group_by", since = "1.77.0")]
impl<'a, T: 'a, P> ChunkBy<'a, T, P> {
    pub(super) fn new(slice: &'a [T], predicate: P) -> Self {
        ChunkBy { slice, predicate }
    }
}
#[stable(feature = "slice_group_by", since = "1.77.0")]
impl<'a, T: 'a, P> Iterator for ChunkBy<'a, T, P>
where
    P: FnMut(&T, &T) -> bool,
{
    type Item = &'a [T];
    #[inline]
    fn next(&mut self) -> Option<Self::Item> {
        if self.slice.is_empty() {
            None
        } else {
            let mut len = 1;
            let mut iter = self.slice.windows(2);
            while let Some([l, r]) = iter.next() {
                if (self.predicate)(l, r) { len += 1 } else { break }
            }
            let (head, tail) = self.slice.split_at(len);
            self.slice = tail;
            Some(head)
        }
    }
    #[inline]
    fn size_hint(&self) -> (usize, Option<usize>) {
        if self.slice.is_empty() { (0, Some(0)) } else { (1, Some(self.slice.len())) }
    }
    #[inline]
    fn last(mut self) -> Option<Self::Item> {
        self.next_back()
    }
}
#[stable(feature = "slice_group_by", since = "1.77.0")]
impl<'a, T: 'a, P> DoubleEndedIterator for ChunkBy<'a, T, P>
where
    P: FnMut(&T, &T) -> bool,
{
    #[inline]
    fn next_back(&mut self) -> Option<Self::Item> {
        if self.slice.is_empty() {
            None
        } else {
            let mut len = 1;
            let mut iter = self.slice.windows(2);
            while let Some([l, r]) = iter.next_back() {
                if (self.predicate)(l, r) { len += 1 } else { break }
            }
            let (head, tail) = self.slice.split_at(self.slice.len() - len);
            self.slice = head;
            Some(tail)
        }
    }
}
#[stable(feature = "slice_group_by", since = "1.77.0")]
impl<'a, T: 'a, P> FusedIterator for ChunkBy<'a, T, P> where P: FnMut(&T, &T) -> bool {}
#[stable(feature = "slice_group_by", since = "1.77.0")]
impl<'a, T: 'a + fmt::Debug, P> fmt::Debug for ChunkBy<'a, T, P> {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        f.debug_struct("ChunkBy").field("slice", &self.slice).finish()
    }
}
#[stable(feature = "slice_group_by", since = "1.77.0")]
#[must_use = "iterators are lazy and do nothing unless consumed"]
pub struct ChunkByMut<'a, T: 'a, P> {
    slice: &'a mut [T],
    predicate: P,
}
#[stable(feature = "slice_group_by", since = "1.77.0")]
impl<'a, T: 'a, P> ChunkByMut<'a, T, P> {
    pub(super) fn new(slice: &'a mut [T], predicate: P) -> Self {
        ChunkByMut { slice, predicate }
    }
}
#[stable(feature = "slice_group_by", since = "1.77.0")]
impl<'a, T: 'a, P> Iterator for ChunkByMut<'a, T, P>
where
    P: FnMut(&T, &T) -> bool,
{
    type Item = &'a mut [T];
    #[inline]
    fn next(&mut self) -> Option<Self::Item> {
        if self.slice.is_empty() {
            None
        } else {
            let mut len = 1;
            let mut iter = self.slice.windows(2);
            while let Some([l, r]) = iter.next() {
                if (self.predicate)(l, r) { len += 1 } else { break }
            }
            let slice = mem::take(&mut self.slice);
            let (head, tail) = slice.split_at_mut(len);
            self.slice = tail;
            Some(head)
        }
    }
    #[inline]
    fn size_hint(&self) -> (usize, Option<usize>) {
        if self.slice.is_empty() { (0, Some(0)) } else { (1, Some(self.slice.len())) }
    }
    #[inline]
    fn last(mut self) -> Option<Self::Item> {
        self.next_back()
    }
}
#[stable(feature = "slice_group_by", since = "1.77.0")]
impl<'a, T: 'a, P> DoubleEndedIterator for ChunkByMut<'a, T, P>
where
    P: FnMut(&T, &T) -> bool,
{
    #[inline]
    fn next_back(&mut self) -> Option<Self::Item> {
        if self.slice.is_empty() {
            None
        } else {
            let mut len = 1;
            let mut iter = self.slice.windows(2);
            while let Some([l, r]) = iter.next_back() {
                if (self.predicate)(l, r) { len += 1 } else { break }
            }
            let slice = mem::take(&mut self.slice);
            let (head, tail) = slice.split_at_mut(slice.len() - len);
            self.slice = head;
            Some(tail)
        }
    }
}
#[stable(feature = "slice_group_by", since = "1.77.0")]
impl<'a, T: 'a, P> FusedIterator for ChunkByMut<'a, T, P> where P: FnMut(&T, &T) -> bool {}
#[stable(feature = "slice_group_by", since = "1.77.0")]
impl<'a, T: 'a + fmt::Debug, P> fmt::Debug for ChunkByMut<'a, T, P> {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        f.debug_struct("ChunkByMut").field("slice", &self.slice).finish()
    }
}