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    //! Iterators provided by this crate.

    #![cfg_attr(os_str_bytes_docs_rs, doc(cfg(feature = "raw_os_str")))]

    use std::convert;
    use std::fmt;
    use std::fmt::Debug;
    use std::fmt::Formatter;
    use std::iter::FusedIterator;

    use super::pattern::Encoded;
    use super::Pattern;
    use super::RawOsStr;

    // [memchr::memmem::FindIter] is not currently used, since this struct would
    // become self-referential. Additionally, that iterator does not implement
    // [DoubleEndedIterator], and its implementation would likely require
    // significant changes to implement that trait.
    /// The iterator returned by [`RawOsStr::split`].
    pub struct Split<'a, P>
    where
        P: Pattern,
    {
        string: Option<&'a RawOsStr>,
        pat: P::__Encoded,
    }

    impl<'a, P> Split<'a, P>
    where
        P: Pattern,
    {
        #[track_caller]
        pub(super) fn new(string: &'a RawOsStr, pat: P) -> Self {
            let pat = pat.__encode();
            assert!(
                !pat.__get().is_empty(),
                "cannot split using an empty pattern",
            );
            Self {
                string: Some(string),
                pat,
            }
        }
    }

    macro_rules! impl_next {
        ( $self:ident , $split_method:ident , $swap_fn:expr ) => {{
            $self
                .string?
                .$split_method(&$self.pat)
                .map(|substrings| {
                    let (substring, string) = $swap_fn(substrings);
                    $self.string = Some(string);
                    substring
                })
                .or_else(|| $self.string.take())
        }};
    }

    impl<P> Clone for Split<'_, P>
    where
        P: Pattern,
    {
        #[inline]
        fn clone(&self) -> Self {
            Self {
                string: self.string,
                pat: self.pat.clone(),
            }
        }
    }

    impl<P> Debug for Split<'_, P>
    where
        P: Pattern,
    {
        #[inline]
        fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
            f.debug_struct("Split")
                .field("string", &self.string)
                .field("pat", &self.pat)
                .finish()
        }
    }

    impl<P> DoubleEndedIterator for Split<'_, P>
    where
        P: Pattern,
    {
        fn next_back(&mut self) -> Option<Self::Item> {
            impl_next!(self, rsplit_once_raw, |(prefix, suffix)| (suffix, prefix))
        }
    }

    impl<P> FusedIterator for Split<'_, P> where P: Pattern {}

    impl<'a, P> Iterator for Split<'a, P>
    where
        P: Pattern,
    {
        type Item = &'a RawOsStr;

        #[inline]
        fn last(mut self) -> Option<Self::Item> {
            self.next_back()
        }

        fn next(&mut self) -> Option<Self::Item> {
            impl_next!(self, split_once_raw, convert::identity)
        }
    }