1.0.0[−][src]Trait core::iter::IntoIterator

pub trait IntoIterator {
    type Item;
    type IntoIter: Iterator<Item = Self::Item>;
    fn into_iter(self) -> Self::IntoIter;
}

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 = 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());Run

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);
}Run

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()
}Run

Associated Types

type Item

The type of the elements being iterated over.

type IntoIter: Iterator<Item = Self::Item>

Which kind of iterator are we turning this into?

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Required methods

fn into_iter(self) -> Self::IntoIter

Creates an iterator from a value.

See the module-level documentation for more.

Examples

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());Run
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Implementors

impl<'a, T> IntoIterator for &'a Option<T>[src]

type Item = &'a T

type IntoIter = Iter<'a, T>

impl<'a, T> IntoIterator for &'a [T][src]

type Item = &'a T

type IntoIter = Iter<'a, T>

impl<'a, T> IntoIterator for &'a mut Option<T>[src]

type Item = &'a mut T

type IntoIter = IterMut<'a, T>

impl<'a, T> IntoIterator for &'a mut [T][src]

type Item = &'a mut T

type IntoIter = IterMut<'a, T>

impl<'a, T, E> IntoIterator for &'a Result<T, E>[src]

type Item = &'a T

type IntoIter = Iter<'a, T>

impl<'a, T, E> IntoIterator for &'a mut Result<T, E>[src]

type Item = &'a mut T

type IntoIter = IterMut<'a, T>

impl<'a, T, const N: usize> IntoIterator for &'a [T; N] where
    [T; N]: LengthAtMost32, [src]

type Item = &'a T

type IntoIter = Iter<'a, T>

impl<'a, T, const N: usize> IntoIterator for &'a mut [T; N] where
    [T; N]: LengthAtMost32, [src]

type Item = &'a mut T

type IntoIter = IterMut<'a, T>

impl<I: Iterator> IntoIterator for I[src]

type Item = I::Item

type IntoIter = I

impl<T> IntoIterator for Option<T>[src]

type Item = T

type IntoIter = IntoIter<T>

ⓘImportant traits for IntoIter<A>
fn into_iter(self) -> IntoIter<T>[src]

Returns a consuming iterator over the possibly contained value.

Examples

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());Run

impl<T, E> IntoIterator for Result<T, E>[src]

type Item = T

type IntoIter = IntoIter<T>

ⓘImportant traits for IntoIter<T>
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.

Examples

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, []);Run
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