No, there is no trait that provides iter()
.
However, IntoIterator
is implemented on references to some containers. For example, Vec<T>
, &Vec<T>
and &mut Vec<T>
are three separate types that implement IntoIterator
, and you’ll notice that they all map to different iterators. In fact, Vec::iter()
and Vec::iter_mut()
are just convenience methods equivalent to &Vec::into_iter()
and &mut Vec::into_iter()
respectively.
fn foo(_x: std::slice::Iter<i32>) {}
fn main() {
let v = vec![1, 2, 3];
foo(v.iter());
foo((&v).into_iter()); // iter() exists because this is awkward
}
If you want to write a function that is generic over containers that can be converted into an iterator that iterates over references, you can do so like this:
fn foo<'a, I: IntoIterator<Item=&'a i32>>(_x: I) {}
fn main() {
let v = vec![1, 2, 3];
foo(&v);
}