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//@ run-pass
trait Iterable {
type Item<'a> where Self: 'a;
type Iter<'a>: Iterator<Item = Self::Item<'a>> where Self: 'a;
fn iter<'a>(&'a self) -> Self::Iter<'a>;
}
// Impl for struct type
impl<T> Iterable for Vec<T> {
type Item<'a> = <std::slice::Iter<'a, T> as Iterator>::Item where T: 'a;
type Iter<'a> = std::slice::Iter<'a, T> where T: 'a;
fn iter<'a>(&'a self) -> Self::Iter<'a> {
self[..].iter()
}
}
// Impl for a primitive type
impl<T> Iterable for [T] {
type Item<'a> = <std::slice::Iter<'a, T> as Iterator>::Item where T: 'a;
type Iter<'a> = std::slice::Iter<'a, T> where T: 'a;
fn iter<'a>(&'a self) -> Self::Iter<'a> {
self.iter()
}
}
fn make_iter<'a, I: Iterable + ?Sized>(it: &'a I) -> I::Iter<'a> {
it.iter()
}
fn get_first<'a, I: Iterable + ?Sized>(it: &'a I) -> Option<I::Item<'a>> {
it.iter().next()
}
fn main() {
let v = vec![1, 2, 3];
assert_eq!(v, make_iter(&v).copied().collect::<Vec<_>>());
assert_eq!(v, make_iter(&*v).copied().collect::<Vec<_>>());
assert_eq!(Some(&1), get_first(&v));
assert_eq!(Some(&1), get_first(&*v));
}
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