Conversion into an Iterator
.
By implementing IntoIterator
for a type, you define how it will be
converted to an iterator. This is common for types which describe a
collection of some kind.
One benefit of implementing IntoIterator
is that your type will work
with Rust’s for
loop syntax.
See also: FromIterator
.
Basic usage:
let v = vec![1, 2, 3];
let mut iter = v.into_iter();
assert_eq!(Some(1), iter.next());
assert_eq!(Some(2), iter.next());
assert_eq!(Some(3), iter.next());
assert_eq!(None, iter.next());
Implementing IntoIterator
for your type:
#[derive(Debug)]
struct MyCollection(Vec<i32>);
impl MyCollection {
fn new() -> MyCollection {
MyCollection(Vec::new())
}
fn add(&mut self, elem: i32) {
self.0.push(elem);
}
}
impl IntoIterator for MyCollection {
type Item = i32;
type IntoIter = std::vec::IntoIter<Self::Item>;
fn into_iter(self) -> Self::IntoIter {
self.0.into_iter()
}
}
let mut c = MyCollection::new();
c.add(0);
c.add(1);
c.add(2);
for (i, n) in c.into_iter().enumerate() {
assert_eq!(i as i32, n);
}
It is common to use IntoIterator
as a trait bound. This allows
the input collection type to change, so long as it is still an
iterator. Additional bounds can be specified by restricting on
Item
:
fn collect_as_strings<T>(collection: T) -> Vec<String>
where
T: IntoIterator,
T::Item: std::fmt::Debug,
{
collection
.into_iter()
.map(|item| format!("{:?}", item))
.collect()
}
The type of the elements being iterated over.
Which kind of iterator are we turning this into?
Creates an iterator from a value.
See the module-level documentation for more.
Basic usage:
let v = vec![1, 2, 3];
let mut iter = v.into_iter();
assert_eq!(Some(1), iter.next());
assert_eq!(Some(2), iter.next());
assert_eq!(Some(3), iter.next());
assert_eq!(None, iter.next());
impl<'a, T> IntoIterator for &'a mut [T]
[src][+]
impl<'a, T, E> IntoIterator for &'a Result<T, E>
1.4.0[src][+]
impl<'a, T, E> IntoIterator for &'a mut Result<T, E>
1.4.0[src][+]
impl<'a, T, const N: usize> IntoIterator for &'a [T; N]
[src][+]
impl<'a, T, const N: usize> IntoIterator for &'a mut [T; N]
[src][+]
impl<I> IntoIterator for I where
I: Iterator,
[src][+]
impl<T> IntoIterator for Option<T>
[src][+]
type Item = T
type IntoIter = IntoIter<T>
pub fn into_iter(self) -> IntoIter<T>ⓘ
[src][−]
Returns a consuming iterator over the possibly contained value.
let x = Some("string");
let v: Vec<&str> = x.into_iter().collect();
assert_eq!(v, ["string"]);
let x = None;
let v: Vec<&str> = x.into_iter().collect();
assert!(v.is_empty());
impl<T, E> IntoIterator for Result<T, E>
[src][+]
type Item = T
type IntoIter = IntoIter<T>
pub fn into_iter(self) -> IntoIter<T>ⓘ
[src][−]
Returns a consuming iterator over the possibly contained value.
The iterator yields one value if the result is Result::Ok
, otherwise none.
Basic usage:
let x: Result<u32, &str> = Ok(5);
let v: Vec<u32> = x.into_iter().collect();
assert_eq!(v, [5]);
let x: Result<u32, &str> = Err("nothing!");
let v: Vec<u32> = x.into_iter().collect();
assert_eq!(v, []);