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use std::iter::Peekable;
pub struct Enumerate<I>
where
I: Iterator,
{
iter: Peekable<I>,
count: usize,
}
impl<I> Iterator for Enumerate<I>
where
I: Iterator,
{
type Item = (usize, bool, <I as Iterator>::Item);
#[inline]
fn next(&mut self) -> Option<(usize, bool, <I as Iterator>::Item)> {
self.iter.next().map(|a| {
let last = self.iter.peek().is_none();
let ret = (self.count, last, a);
// Possible undefined overflow.
self.count += 1;
ret
})
}
#[inline]
fn size_hint(&self) -> (usize, Option<usize>) {
self.iter.size_hint()
}
#[inline]
fn count(self) -> usize {
self.iter.count()
}
}
#[inline]
pub fn enumerate<I>(iter: I) -> Enumerate<I>
where
I: Iterator,
{
Enumerate {
iter: iter.peekable(),
count: 0,
}
}
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