use crate::{Consumer, Iterable, IterableSeq};
#[must_use = "iterable adaptors are lazy and do nothing unless consumed"]
#[derive(Debug, Clone)]
pub struct LazyRev<I> {
pub(crate) iterable: I,
}
impl<I> Iterable for LazyRev<I>
where
I: Iterable,
I::IntoIter: DoubleEndedIterator,
{
type C = I::C;
type CC<U> = I::CC<U>;
type F = I::F;
type CF<U> = I::CF<U>;
}
impl<I> IterableSeq for LazyRev<I>
where
I: IterableSeq,
I::IntoIter: DoubleEndedIterator,
{
}
impl<I> Consumer for LazyRev<I>
where
I: Consumer,
I::IntoIter: DoubleEndedIterator,
{
type Item = I::Item;
type IntoIter = std::iter::Rev<I::IntoIter>;
fn consume(self) -> Self::IntoIter {
self.iterable.consume().rev()
}
}
#[cfg(test)]
mod tests {
use super::*;
use crate::assert_type;
use crate::lazy::collect;
#[test]
fn smoke() {
let v = vec![1, 2, 3];
let res = collect(v.lazy_rev());
assert_eq!(res, vec![3, 2, 1]);
}
#[test]
fn test_f() {
let v = [1, 2, 3];
let res = v.lazy_rev().rev();
assert_type::<[i32; 3]>(res.clone());
assert_eq!(res, [1, 2, 3]);
}
#[test]
fn test_cf() {
let v = [1, 2, 3];
let res = v.lazy_rev().map(|x| x.to_string());
assert_type::<[String; 3]>(res);
}
}