src/test/ui/generic-associated-types/iterable.rs

   1 #![feature(generic_associated_types)]
   2
   3 // run-pass
   4
   5 trait Iterable {
   6     type Item<'a> where Self: 'a;
   7     type Iter<'a>: Iterator<Item = Self::Item<'a>> where Self: 'a;
   8
   9     fn iter<'a>(&'a self) -> Self::Iter<'a>;
  10 }
  11
  12 // Impl for struct type
  13 impl<T> Iterable for Vec<T> {
  14     type Item<'a> where T: 'a = <std::slice::Iter<'a, T> as Iterator>::Item;
  15     type Iter<'a> where T: 'a = std::slice::Iter<'a, T>;
  16
  17     fn iter<'a>(&'a self) -> Self::Iter<'a> {
  18         self[..].iter()
  19     }
  20 }
  21
  22 // Impl for a primitive type
  23 impl<T> Iterable for [T] {
  24     type Item<'a> where T: 'a = <std::slice::Iter<'a, T> as Iterator>::Item;
  25     type Iter<'a> where T: 'a = std::slice::Iter<'a, T>;
  26
  27     fn iter<'a>(&'a self) -> Self::Iter<'a> {
  28         self.iter()
  29     }
  30 }
  31
  32 fn make_iter<'a, I: Iterable + ?Sized>(it: &'a I) -> I::Iter<'a> {
  33     it.iter()
  34 }
  35
  36 fn get_first<'a, I: Iterable + ?Sized>(it: &'a I) -> Option<I::Item<'a>> {
  37     it.iter().next()
  38 }
  39
  40 fn main() {
  41     let v = vec![1, 2, 3];
  42     assert_eq!(v, make_iter(&v).copied().collect::<Vec<_>>());
  43     assert_eq!(v, make_iter(&*v).copied().collect::<Vec<_>>());
  44     assert_eq!(Some(&1), get_first(&v));
  45     assert_eq!(Some(&1), get_first(&*v));
  46 }