use std::iter::{Zip, Skip};
use std::slice::Iter;
pub trait PairWise<T> {
fn pairwise(&self) -> Zip<Iter<T>, Skip<Iter<T>>>;
}
impl<T> PairWise<T> for [T] {
fn pairwise(&self) -> Zip<Iter<T>, Skip<Iter<T>>> {
self.iter().zip(self.iter().skip(1))
}
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn test_pairwise() {
let a = [1, 2, 3, 4, 5];
assert_eq!(a.pairwise().nth(0).unwrap(), (&1, &2));
assert_eq!(a.pairwise().last().unwrap(), (&4, &5));
assert_eq!(a.pairwise().len(), a.len() - 1);
let a = [1, 2];
assert_eq!(a.pairwise().nth(0).unwrap(), (&1, &2));
assert_eq!(a.pairwise().last().unwrap(), (&1, &2));
assert_eq!(a.pairwise().len(), a.len() - 1);
let a = [1];
assert!(a.pairwise().nth(0).is_none());
let b: Vec<f64> = vec![0.0, 0.1, 0.2];
assert_eq!(b.pairwise().nth(0).unwrap(), (&0.0, &0.1));
}
}