1.0.0[][src]Trait std::iter::IntoIterator

pub trait IntoIterator where
    <Self::IntoIter as Iterator>::Item == Self::Item
{ type Item; type IntoIter: Iterator; 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

The type of the elements being iterated over.

Which kind of iterator are we turning this into?

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Required methods

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> IntoIterator for &'a UnixListener
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impl<'a> IntoIterator for &'a Path
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impl<'a> IntoIterator for &'a PathBuf
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impl<'a, K, V> IntoIterator for &'a BTreeMap<K, V> where
    K: 'a,
    V: 'a, 
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impl<'a, K, V> IntoIterator for &'a mut BTreeMap<K, V> where
    K: 'a,
    V: 'a, 
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impl<'a, K, V, S> IntoIterator for &'a HashMap<K, V, S> where
    K: Eq + Hash,
    S: BuildHasher
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impl<'a, K, V, S> IntoIterator for &'a mut HashMap<K, V, S> where
    K: Eq + Hash,
    S: BuildHasher
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impl<'a, T> IntoIterator for &'a Option<T>
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impl<'a, T> IntoIterator for &'a [T; 0]
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impl<'a, T> IntoIterator for &'a [T; 1]
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impl<'a, T> IntoIterator for &'a [T; 2]
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impl<'a, T> IntoIterator for &'a [T; 3]
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impl<'a, T> IntoIterator for &'a [T; 4]
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impl<'a, T> IntoIterator for &'a [T; 5]
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impl<'a, T> IntoIterator for &'a [T; 6]
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impl<'a, T> IntoIterator for &'a [T; 7]
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impl<'a, T> IntoIterator for &'a [T; 8]
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impl<'a, T> IntoIterator for &'a [T; 9]
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impl<'a, T> IntoIterator for &'a [T; 10]
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impl<'a, T> IntoIterator for &'a [T; 11]
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impl<'a, T> IntoIterator for &'a [T; 12]
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impl<'a, T> IntoIterator for &'a [T; 13]
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impl<'a, T> IntoIterator for &'a [T; 14]
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impl<'a, T> IntoIterator for &'a [T; 15]
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impl<'a, T> IntoIterator for &'a [T; 16]
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impl<'a, T> IntoIterator for &'a [T; 17]
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impl<'a, T> IntoIterator for &'a [T; 18]
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impl<'a, T> IntoIterator for &'a [T; 19]
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impl<'a, T> IntoIterator for &'a [T; 20]
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impl<'a, T> IntoIterator for &'a [T; 21]
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impl<'a, T> IntoIterator for &'a [T; 22]
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impl<'a, T> IntoIterator for &'a [T; 23]
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impl<'a, T> IntoIterator for &'a [T; 24]
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impl<'a, T> IntoIterator for &'a [T; 25]
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impl<'a, T> IntoIterator for &'a [T; 26]
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impl<'a, T> IntoIterator for &'a [T; 27]
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impl<'a, T> IntoIterator for &'a [T; 28]
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impl<'a, T> IntoIterator for &'a [T; 29]
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impl<'a, T> IntoIterator for &'a [T; 30]
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impl<'a, T> IntoIterator for &'a [T; 31]
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impl<'a, T> IntoIterator for &'a [T; 32]
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impl<'a, T> IntoIterator for &'a BinaryHeap<T> where
    T: Ord
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impl<'a, T> IntoIterator for &'a BTreeSet<T>
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impl<'a, T> IntoIterator for &'a LinkedList<T>
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impl<'a, T> IntoIterator for &'a VecDeque<T>
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impl<'a, T> IntoIterator for &'a Receiver<T>
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impl<'a, T> IntoIterator for &'a Vec<T>
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impl<'a, T> IntoIterator for &'a mut Option<T>
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impl<'a, T> IntoIterator for &'a mut [T; 0]
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impl<'a, T> IntoIterator for &'a mut [T; 1]
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impl<'a, T> IntoIterator for &'a mut [T; 2]
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impl<'a, T> IntoIterator for &'a mut [T; 3]
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impl<'a, T> IntoIterator for &'a mut [T; 4]
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impl<'a, T> IntoIterator for &'a mut [T; 5]
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impl<'a, T> IntoIterator for &'a mut [T; 6]
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impl<'a, T> IntoIterator for &'a mut [T; 7]
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impl<'a, T> IntoIterator for &'a mut [T; 8]
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impl<'a, T> IntoIterator for &'a mut [T; 9]
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impl<'a, T> IntoIterator for &'a mut [T; 10]
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impl<'a, T> IntoIterator for &'a mut [T; 11]
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impl<'a, T> IntoIterator for &'a mut [T; 12]
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impl<'a, T> IntoIterator for &'a mut [T; 13]
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impl<'a, T> IntoIterator for &'a mut [T; 14]
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impl<'a, T> IntoIterator for &'a mut [T; 15]
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impl<'a, T> IntoIterator for &'a mut [T; 16]
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impl<'a, T> IntoIterator for &'a mut [T; 17]
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impl<'a, T> IntoIterator for &'a mut [T; 18]
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impl<'a, T> IntoIterator for &'a mut [T; 19]
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impl<'a, T> IntoIterator for &'a mut [T; 20]
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impl<'a, T> IntoIterator for &'a mut [T; 21]
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impl<'a, T> IntoIterator for &'a mut [T; 22]
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impl<'a, T> IntoIterator for &'a mut [T; 23]
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impl<'a, T> IntoIterator for &'a mut [T; 24]
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impl<'a, T> IntoIterator for &'a mut [T; 25]
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impl<'a, T> IntoIterator for &'a mut [T; 26]
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impl<'a, T> IntoIterator for &'a mut [T; 27]
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impl<'a, T> IntoIterator for &'a mut [T; 28]
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impl<'a, T> IntoIterator for &'a mut [T; 29]
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impl<'a, T> IntoIterator for &'a mut [T; 30]
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impl<'a, T> IntoIterator for &'a mut [T; 31]
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impl<'a, T> IntoIterator for &'a mut [T; 32]
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impl<'a, T> IntoIterator for &'a mut LinkedList<T>
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impl<'a, T> IntoIterator for &'a mut VecDeque<T>
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impl<'a, T> IntoIterator for &'a mut Vec<T>
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impl<'a, T> IntoIterator for &'a [T]
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impl<'a, T> IntoIterator for &'a mut [T]
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impl<'a, T, E> IntoIterator for &'a Result<T, E>
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impl<'a, T, E> IntoIterator for &'a mut Result<T, E>
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impl<'a, T, S> IntoIterator for &'a HashSet<T, S> where
    T: Eq + Hash,
    S: BuildHasher
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impl<I> IntoIterator for I where
    I: Iterator
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impl<K, V> IntoIterator for BTreeMap<K, V>
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impl<K, V, S> IntoIterator for HashMap<K, V, S> where
    K: Eq + Hash,
    S: BuildHasher
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Important traits for IntoIter<K, V>

Creates a consuming iterator, that is, one that moves each key-value pair out of the map in arbitrary order. The map cannot be used after calling this.

Examples

use std::collections::HashMap;

let mut map = HashMap::new();
map.insert("a", 1);
map.insert("b", 2);
map.insert("c", 3);

// Not possible with .iter()
let vec: Vec<(&str, i32)> = map.into_iter().collect();Run

impl<T> IntoIterator for Option<T>
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Important traits for IntoIter<A>

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> IntoIterator for BinaryHeap<T> where
    T: Ord
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Important traits for IntoIter<T>

Creates a consuming iterator, that is, one that moves each value out of the binary heap in arbitrary order. The binary heap cannot be used after calling this.

Examples

Basic usage:

use std::collections::BinaryHeap;
let heap = BinaryHeap::from(vec![1, 2, 3, 4]);

// Print 1, 2, 3, 4 in arbitrary order
for x in heap.into_iter() {
    // x has type i32, not &i32
    println!("{}", x);
}Run

impl<T> IntoIterator for BTreeSet<T>
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Important traits for IntoIter<T>

Gets an iterator for moving out the BTreeSet's contents.

Examples

use std::collections::BTreeSet;

let set: BTreeSet<usize> = [1, 2, 3, 4].iter().cloned().collect();

let v: Vec<_> = set.into_iter().collect();
assert_eq!(v, [1, 2, 3, 4]);Run

impl<T> IntoIterator for LinkedList<T>
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Important traits for IntoIter<T>

Consumes the list into an iterator yielding elements by value.

impl<T> IntoIterator for VecDeque<T>
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Important traits for IntoIter<T>

Consumes the VecDeque into a front-to-back iterator yielding elements by value.

impl<T> IntoIterator for Receiver<T>
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impl<T> IntoIterator for Vec<T>
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Important traits for IntoIter<T>

Creates a consuming iterator, that is, one that moves each value out of the vector (from start to end). The vector cannot be used after calling this.

Examples

let v = vec!["a".to_string(), "b".to_string()];
for s in v.into_iter() {
    // s has type String, not &String
    println!("{}", s);
}Run

impl<T, E> IntoIterator for Result<T, E>
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Important traits for IntoIter<T>

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

impl<T, S> IntoIterator for HashSet<T, S> where
    T: Eq + Hash,
    S: BuildHasher
[src]

Important traits for IntoIter<K>

Creates a consuming iterator, that is, one that moves each value out of the set in arbitrary order. The set cannot be used after calling this.

Examples

use std::collections::HashSet;
let mut set = HashSet::new();
set.insert("a".to_string());
set.insert("b".to_string());

// Not possible to collect to a Vec<String> with a regular `.iter()`.
let v: Vec<String> = set.into_iter().collect();

// Will print in an arbitrary order.
for x in &v {
    println!("{}", x);
}Run
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