iterable/lazy/
lazy_enumerate.rs

1use crate::{Consumer, Iterable, IterableSeq};
2
3#[must_use = "iterable adaptors are lazy and do nothing unless consumed"]
4#[derive(Debug, Clone)]
5pub struct LazyEnumerate<I> {
6    pub(crate) iterable: I,
7}
8
9impl<I> Iterable for LazyEnumerate<I>
10where
11    I: Iterable,
12{
13    type C = I::CC<(usize, I::Item)>;
14    type CC<U> = I::CC<U>;
15    type F = I::CF<(usize, I::Item)>;
16    type CF<U> = I::CF<U>;
17}
18
19impl<I> IterableSeq for LazyEnumerate<I> where I: IterableSeq {}
20
21impl<I> Consumer for LazyEnumerate<I>
22where
23    I: Consumer,
24{
25    type Item = (usize, I::Item);
26    type IntoIter = std::iter::Enumerate<I::IntoIter>;
27    fn consume(self) -> Self::IntoIter {
28        self.iterable.consume().enumerate()
29    }
30}
31
32#[cfg(test)]
33mod tests {
34    use super::*;
35    use crate::assert_type;
36    use crate::lazy::collect;
37
38    #[test]
39    fn smoke() {
40        let v = vec![1, 2, 3];
41        let res = collect(v.lazy_enumerate());
42        assert_eq!(res, vec![(0, 1), (1, 2), (2, 3)]);
43    }
44
45    #[test]
46    fn test_f() {
47        let v = [1, 2, 3];
48        let res = v.lazy_enumerate().rev();
49        assert_type::<[(usize, i32); 3]>(res);
50    }
51
52    #[test]
53    fn test_cf() {
54        let v = [1, 2, 3];
55        let res = v.lazy_enumerate().map(|(_, s)| s.to_string());
56        assert_type::<[String; 3]>(res);
57    }
58}
iterable/lazy/lazy_enumerate.rs

iterable/lazy/
lazy_enumerate.rs
