core::iter::IntoIterator - Rust
Description: API documentation for the Rust `IntoIterator` trait in crate `core`.
Keywords: rust, rustlang, rust-lang, IntoIterator

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

    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<i32>;

        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?

## 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

## Implementors

- `impl<'a, T> IntoIterator for &'a [T; 0] type Item = &'a T; type IntoIter = Iter<'a, T>;`
- `impl<'a, T> IntoIterator for &'a mut [T; 0] type Item = &'a mut T; type IntoIter = IterMut<'a, T>;`
- `impl<'a, T> IntoIterator for &'a [T; 1] type Item = &'a T; type IntoIter = Iter<'a, T>;`
- `impl<'a, T> IntoIterator for &'a mut [T; 1] type Item = &'a mut T; type IntoIter = IterMut<'a, T>;`
- `impl<'a, T> IntoIterator for &'a [T; 2] type Item = &'a T; type IntoIter = Iter<'a, T>;`
- `impl<'a, T> IntoIterator for &'a mut [T; 2] type Item = &'a mut T; type IntoIter = IterMut<'a, T>;`
- `impl<'a, T> IntoIterator for &'a [T; 3] type Item = &'a T; type IntoIter = Iter<'a, T>;`
- `impl<'a, T> IntoIterator for &'a mut [T; 3] type Item = &'a mut T; type IntoIter = IterMut<'a, T>;`
- `impl<'a, T> IntoIterator for &'a [T; 4] type Item = &'a T; type IntoIter = Iter<'a, T>;`
- `impl<'a, T> IntoIterator for &'a mut [T; 4] type Item = &'a mut T; type IntoIter = IterMut<'a, T>;`
- `impl<'a, T> IntoIterator for &'a [T; 5] type Item = &'a T; type IntoIter = Iter<'a, T>;`
- `impl<'a, T> IntoIterator for &'a mut [T; 5] type Item = &'a mut T; type IntoIter = IterMut<'a, T>;`
- `impl<'a, T> IntoIterator for &'a [T; 6] type Item = &'a T; type IntoIter = Iter<'a, T>;`
- `impl<'a, T> IntoIterator for &'a mut [T; 6] type Item = &'a mut T; type IntoIter = IterMut<'a, T>;`
- `impl<'a, T> IntoIterator for &'a [T; 7] type Item = &'a T; type IntoIter = Iter<'a, T>;`
- `impl<'a, T> IntoIterator for &'a mut [T; 7] type Item = &'a mut T; type IntoIter = IterMut<'a, T>;`
- `impl<'a, T> IntoIterator for &'a [T; 8] type Item = &'a T; type IntoIter = Iter<'a, T>;`
- `impl<'a, T> IntoIterator for &'a mut [T; 8] type Item = &'a mut T; type IntoIter = IterMut<'a, T>;`
- `impl<'a, T> IntoIterator for &'a [T; 9] type Item = &'a T; type IntoIter = Iter<'a, T>;`
- `impl<'a, T> IntoIterator for &'a mut [T; 9] type Item = &'a mut T; type IntoIter = IterMut<'a, T>;`
- `impl<'a, T> IntoIterator for &'a [T; 10] type Item = &'a T; type IntoIter = Iter<'a, T>;`
- `impl<'a, T> IntoIterator for &'a mut [T; 10] type Item = &'a mut T; type IntoIter = IterMut<'a, T>;`
- `impl<'a, T> IntoIterator for &'a [T; 11] type Item = &'a T; type IntoIter = Iter<'a, T>;`
- `impl<'a, T> IntoIterator for &'a mut [T; 11] type Item = &'a mut T; type IntoIter = IterMut<'a, T>;`
- `impl<'a, T> IntoIterator for &'a [T; 12] type Item = &'a T; type IntoIter = Iter<'a, T>;`
- `impl<'a, T> IntoIterator for &'a mut [T; 12] type Item = &'a mut T; type IntoIter = IterMut<'a, T>;`
- `impl<'a, T> IntoIterator for &'a [T; 13] type Item = &'a T; type IntoIter = Iter<'a, T>;`
- `impl<'a, T> IntoIterator for &'a mut [T; 13] type Item = &'a mut T; type IntoIter = IterMut<'a, T>;`
- `impl<'a, T> IntoIterator for &'a [T; 14] type Item = &'a T; type IntoIter = Iter<'a, T>;`
- `impl<'a, T> IntoIterator for &'a mut [T; 14] type Item = &'a mut T; type IntoIter = IterMut<'a, T>;`
- `impl<'a, T> IntoIterator for &'a [T; 15] type Item = &'a T; type IntoIter = Iter<'a, T>;`
- `impl<'a, T> IntoIterator for &'a mut [T; 15] type Item = &'a mut T; type IntoIter = IterMut<'a, T>;`
- `impl<'a, T> IntoIterator for &'a [T; 16] type Item = &'a T; type IntoIter = Iter<'a, T>;`
- `impl<'a, T> IntoIterator for &'a mut [T; 16] type Item = &'a mut T; type IntoIter = IterMut<'a, T>;`
- `impl<'a, T> IntoIterator for &'a [T; 17] type Item = &'a T; type IntoIter = Iter<'a, T>;`
- `impl<'a, T> IntoIterator for &'a mut [T; 17] type Item = &'a mut T; type IntoIter = IterMut<'a, T>;`
- `impl<'a, T> IntoIterator for &'a [T; 18] type Item = &'a T; type IntoIter = Iter<'a, T>;`
- `impl<'a, T> IntoIterator for &'a mut [T; 18] type Item = &'a mut T; type IntoIter = IterMut<'a, T>;`
- `impl<'a, T> IntoIterator for &'a [T; 19] type Item = &'a T; type IntoIter = Iter<'a, T>;`
- `impl<'a, T> IntoIterator for &'a mut [T; 19] type Item = &'a mut T; type IntoIter = IterMut<'a, T>;`
- `impl<'a, T> IntoIterator for &'a [T; 20] type Item = &'a T; type IntoIter = Iter<'a, T>;`
- `impl<'a, T> IntoIterator for &'a mut [T; 20] type Item = &'a mut T; type IntoIter = IterMut<'a, T>;`
- `impl<'a, T> IntoIterator for &'a [T; 21] type Item = &'a T; type IntoIter = Iter<'a, T>;`
- `impl<'a, T> IntoIterator for &'a mut [T; 21] type Item = &'a mut T; type IntoIter = IterMut<'a, T>;`
- `impl<'a, T> IntoIterator for &'a [T; 22] type Item = &'a T; type IntoIter = Iter<'a, T>;`
- `impl<'a, T> IntoIterator for &'a mut [T; 22] type Item = &'a mut T; type IntoIter = IterMut<'a, T>;`
- `impl<'a, T> IntoIterator for &'a [T; 23] type Item = &'a T; type IntoIter = Iter<'a, T>;`
- `impl<'a, T> IntoIterator for &'a mut [T; 23] type Item = &'a mut T; type IntoIter = IterMut<'a, T>;`
- `impl<'a, T> IntoIterator for &'a [T; 24] type Item = &'a T; type IntoIter = Iter<'a, T>;`
- `impl<'a, T> IntoIterator for &'a mut [T; 24] type Item = &'a mut T; type IntoIter = IterMut<'a, T>;`
- `impl<'a, T> IntoIterator for &'a [T; 25] type Item = &'a T; type IntoIter = Iter<'a, T>;`
- `impl<'a, T> IntoIterator for &'a mut [T; 25] type Item = &'a mut T; type IntoIter = IterMut<'a, T>;`
- `impl<'a, T> IntoIterator for &'a [T; 26] type Item = &'a T; type IntoIter = Iter<'a, T>;`
- `impl<'a, T> IntoIterator for &'a mut [T; 26] type Item = &'a mut T; type IntoIter = IterMut<'a, T>;`
- `impl<'a, T> IntoIterator for &'a [T; 27] type Item = &'a T; type IntoIter = Iter<'a, T>;`
- `impl<'a, T> IntoIterator for &'a mut [T; 27] type Item = &'a mut T; type IntoIter = IterMut<'a, T>;`
- `impl<'a, T> IntoIterator for &'a [T; 28] type Item = &'a T; type IntoIter = Iter<'a, T>;`
- `impl<'a, T> IntoIterator for &'a mut [T; 28] type Item = &'a mut T; type IntoIter = IterMut<'a, T>;`
- `impl<'a, T> IntoIterator for &'a [T; 29] type Item = &'a T; type IntoIter = Iter<'a, T>;`
- `impl<'a, T> IntoIterator for &'a mut [T; 29] type Item = &'a mut T; type IntoIter = IterMut<'a, T>;`
- `impl<'a, T> IntoIterator for &'a [T; 30] type Item = &'a T; type IntoIter = Iter<'a, T>;`
- `impl<'a, T> IntoIterator for &'a mut [T; 30] type Item = &'a mut T; type IntoIter = IterMut<'a, T>;`
- `impl<'a, T> IntoIterator for &'a [T; 31] type Item = &'a T; type IntoIter = Iter<'a, T>;`
- `impl<'a, T> IntoIterator for &'a mut [T; 31] type Item = &'a mut T; type IntoIter = IterMut<'a, T>;`
- `impl<'a, T> IntoIterator for &'a [T; 32] type Item = &'a T; type IntoIter = Iter<'a, T>;`
- `impl<'a, T> IntoIterator for &'a mut [T; 32] type Item = &'a mut T; type IntoIter = IterMut<'a, T>;`
- `impl<I: Iterator> IntoIterator for I type Item = I::Item; type IntoIter = I;`
- [src]
  `impl<T> IntoIterator for Option<T> type Item = T; type IntoIter = IntoIter<T>;`
- [src]
  `impl<'a, T> IntoIterator for &'a Option<T> type Item = &'a T; type IntoIter = Iter<'a, T>;`
- [src]
  `impl<'a, T> IntoIterator for &'a mut Option<T> type Item = &'a mut T; type IntoIter = IterMut<'a, T>;`
- [src]
  `impl<T, E> IntoIterator for Result<T, E> type Item = T; type IntoIter = IntoIter<T>;`
- [src]
  `impl<'a, T, E> IntoIterator for &'a Result<T, E> type Item = &'a T; type IntoIter = Iter<'a, T>;`
- [src]
  `impl<'a, T, E> IntoIterator for &'a mut Result<T, E> type Item = &'a mut T; type IntoIter = IterMut<'a, T>;`
- `impl<'a, T> IntoIterator for &'a [T] type Item = &'a T; type IntoIter = Iter<'a, T>;`
- `impl<'a, T> IntoIterator for &'a mut [T] type Item = &'a mut T; type IntoIter = IterMut<'a, T>;`

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