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use crate::{Consumer, Iterable, IterableSeq};
#[must_use = "iterable adaptors are lazy and do nothing unless consumed"]
#[derive(Debug, Clone)]
pub struct LazyEnumerate<I> {
pub(crate) iterable: I,
}
impl<I> Iterable for LazyEnumerate<I>
where
I: Iterable,
{
type C = I::CC<(usize, I::Item)>;
type CC<U> = I::CC<U>;
type F = I::CF<(usize, I::Item)>;
type CF<U> = I::CF<U>;
}
impl<I> IterableSeq for LazyEnumerate<I> where I: IterableSeq {}
impl<I> Consumer for LazyEnumerate<I>
where
I: Consumer,
{
type Item = (usize, I::Item);
type IntoIter = std::iter::Enumerate<I::IntoIter>;
fn consume(self) -> Self::IntoIter {
self.iterable.consume().enumerate()
}
}
#[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_enumerate());
assert_eq!(res, vec![(0, 1), (1, 2), (2, 3)]);
}
#[test]
fn test_f() {
let v = [1, 2, 3];
let res = v.lazy_enumerate().rev();
assert_type::<[(usize, i32); 3]>(res);
}
#[test]
fn test_cf() {
let v = [1, 2, 3];
let res = v.lazy_enumerate().map(|(_, s)| s.to_string());
assert_type::<[String; 3]>(res);
}
}