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use std::iter::Fuse;
use super::size_hint;
#[derive(Clone)]
pub struct Intersperse<I> where
I: Iterator,
{
element: I::Item,
iter: Fuse<I>,
peek: Option<I::Item>,
}
impl<I> Intersperse<I> where
I: Iterator,
{
pub fn new(iter: I, elt: I::Item) -> Self
{
let mut iter = iter.fuse();
Intersperse{peek: iter.next(), iter: iter, element: elt}
}
}
impl<I> Iterator for Intersperse<I> where
I: Iterator,
I::Item: Clone,
{
type Item = I::Item;
#[inline]
fn next(&mut self) -> Option<I::Item>
{
if self.peek.is_some() {
self.peek.take()
} else {
self.peek = self.iter.next();
if self.peek.is_some() {
Some(self.element.clone())
} else {
None
}
}
}
fn size_hint(&self) -> (usize, Option<usize>)
{
let has_peek = self.peek.is_some() as usize;
let sh = self.iter.size_hint();
size_hint::add_scalar(
size_hint::add(sh, sh), has_peek)
}
}