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use std::fmt::Debug;
use std::iter::Peekable;
pub trait IteratorExt: Sized + Iterator
{
/// Returns an iterator over overlapping item tuples.
fn windows(self) -> Windows<Self>;
}
impl<Iter: Iterator> IteratorExt for Iter
where
Iter::Item: Clone,
{
fn windows(self) -> Windows<Self>
{
Windows {
iter: self.peekable(),
}
}
}
pub struct Windows<Iter: Iterator>
{
iter: Peekable<Iter>,
}
impl<Iter: Iterator> Iterator for Windows<Iter>
where
Iter::Item: Clone + Debug,
{
type Item = (Iter::Item, Option<Iter::Item>);
fn next(&mut self) -> Option<Self::Item>
{
let opt_first = self.iter.next();
let opt_second = self.iter.peek();
let Some(first) = opt_first else {
return None;
};
Some((first, opt_second.cloned()))
}
}
#[cfg(test)]
mod tests
{
use pretty_assertions::assert_eq;
use super::*;
#[test]
fn windows_works()
{
let mut windows = (0..6).windows();
assert_eq!(windows.next(), Some((0, Some(1))));
assert_eq!(windows.next(), Some((1, Some(2))));
assert_eq!(windows.next(), Some((2, Some(3))));
assert_eq!(windows.next(), Some((3, Some(4))));
assert_eq!(windows.next(), Some((4, Some(5))));
assert_eq!(windows.next(), Some((5, None)));
}
}
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