Trait IntoIterator
pub trait IntoIterator {
type Item;
type IntoIter: Iterator<Item = Self::Item>;
// Required method
fn into_iter(self) -> Self::IntoIter;
}Expand description
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.
§Examples
Basic usage:
let v = [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:
// A sample collection, that's just a wrapper over Vec<T>
#[derive(Debug)]
struct MyCollection(Vec<i32>);
// Let's give it some methods so we can create one and add things
// to it.
impl MyCollection {
fn new() -> MyCollection {
MyCollection(Vec::new())
}
fn add(&mut self, elem: i32) {
self.0.push(elem);
}
}
// and we'll implement IntoIterator
impl IntoIterator for MyCollection {
type Item = i32;
type IntoIter = std::vec::IntoIter<Self::Item>;
fn into_iter(self) -> Self::IntoIter {
self.0.into_iter()
}
}
// Now we can make a new collection...
let mut c = MyCollection::new();
// ... add some stuff to it ...
c.add(0);
c.add(1);
c.add(2);
// ... and then turn it into an Iterator:
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()
}Required Associated Types§
1.0.0type Item
type Item
The type of the elements being iterated over.
Required Methods§
1.0.0fn into_iter(self) -> Self::IntoIter
fn into_iter(self) -> Self::IntoIter
Creates an iterator from a value.
See the module-level documentation for more.
§Examples
let v = [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());