Trait IntoIterator

1.0.0 · Source

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.

§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§

1.0.0 · Source

type Item

The type of the elements being iterated over.

1.0.0 · Source

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

Which kind of iterator are we turning this into?

Required Methods§

1.0.0 · Source

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());

IntoIterator

Trait IntoIterator Copy item path

§Examples

Required Associated Types§

type Item

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

Required Methods§

fn into_iter(self) -> Self::IntoIter

§Examples

Implementors§

impl IntoIterator for Fields

type Item = Field

type IntoIter = IntoIter<Field>

impl IntoIterator for Error

type Item = Error

type IntoIter = IntoIter

impl IntoIterator for Array

type Item = Value

type IntoIter = Box<dyn Iterator<Item = Value>>

impl IntoIterator for ArrayOfTables

type Item = Table

type IntoIter = Box<dyn Iterator<Item = Table>>

impl IntoIterator for InlineTable

type Item = (String, Value)

type IntoIter = Box<dyn Iterator<Item = (String, Value)>>

impl IntoIterator for Table

type Item = (String, Item)

type IntoIter = Box<dyn Iterator<Item = (String, Item)>>

impl IntoIterator for derive_deftly_macros::prelude::TokenStream

type Item = TokenTree

type IntoIter = IntoIter

impl IntoIterator for proc_macro::TokenStream

type Item = TokenTree

type IntoIter = IntoIter

impl<'a> IntoIterator for &'a Fields

type Item = &'a Field

type IntoIter = Iter<'a, Field>

impl<'a> IntoIterator for &'a Error

type Item = Error

type IntoIter = Iter<'a>

impl<'a> IntoIterator for &'a UnixListener

type Item = Result<UnixStream, Error>

type IntoIter = Incoming<'a>

impl<'a> IntoIterator for &'a Path

type Item = &'a OsStr

type IntoIter = Iter<'a>

impl<'a> IntoIterator for &'a PathBuf

type Item = &'a OsStr

type IntoIter = Iter<'a>

impl<'a> IntoIterator for &'a mut Fields

type Item = &'a mut Field

type IntoIter = IterMut<'a, Field>

impl<'a, I> IntoIterator for &'a IntoChunks<I>where I: Iterator, <I as Iterator>::Item: 'a,

type Item = Chunk<'a, I>

type IntoIter = Chunks<'a, I>

impl<'a, I, A> IntoIterator for &'a Box<[I], A>where A: Allocator,

type IntoIter = Iter<'a, I>

type Item = &'a I

impl<'a, I, A> IntoIterator for &'a mut Box<[I], A>where A: Allocator,

type IntoIter = IterMut<'a, I>

type Item = &'a mut I

impl<'a, K, I, F> IntoIterator for &'a ChunkBy<K, I, F>where I: Iterator, <I as Iterator>::Item: 'a, F: FnMut(&<I as Iterator>::Item) -> K, K: PartialEq,

type Item = (K, Group<'a, K, I, F>)

type IntoIter = Groups<'a, K, I, F>

impl<'a, K, V> IntoIterator for &'a indexmap::map::slice::Slice<K, V>

type IntoIter = Iter<'a, K, V>

type Item = (&'a K, &'a V)

impl<'a, K, V> IntoIterator for &'a mut indexmap::map::slice::Slice<K, V>

type IntoIter = IterMut<'a, K, V>

type Item = (&'a K, &'a mut V)

impl<'a, K, V, A> IntoIterator for &'a BTreeMap<K, V, A>where A: Allocator + Clone,

type Item = (&'a K, &'a V)

type IntoIter = Iter<'a, K, V>

impl<'a, K, V, A> IntoIterator for &'a mut BTreeMap<K, V, A>where A: Allocator + Clone,

type Item = (&'a K, &'a mut V)

type IntoIter = IterMut<'a, K, V>

impl<'a, K, V, S> IntoIterator for &'a IndexMap<K, V, S>

type Item = (&'a K, &'a V)

type IntoIter = Iter<'a, K, V>

impl<'a, K, V, S> IntoIterator for &'a std::collections::hash::map::HashMap<K, V, S>

Trait IntoIterator

impl<'a, I> IntoIterator for &'a IntoChunks<I>
where I: Iterator, <I as Iterator>::Item: 'a,

impl<'a, I, A> IntoIterator for &'a Box<[I], A>
where A: Allocator,

impl<'a, I, A> IntoIterator for &'a mut Box<[I], A>
where A: Allocator,

impl<'a, K, I, F> IntoIterator for &'a ChunkBy<K, I, F>
where I: Iterator, <I as Iterator>::Item: 'a, F: FnMut(&<I as Iterator>::Item) -> K, K: PartialEq,

impl<'a, K, V, A> IntoIterator for &'a BTreeMap<K, V, A>
where A: Allocator + Clone,

impl<'a, K, V, A> IntoIterator for &'a mut BTreeMap<K, V, A>
where A: Allocator + Clone,

impl<'a, K, V, S, A> IntoIterator for &'a hashbrown::map::HashMap<K, V, S, A>
where A: Allocator,

impl<'a, K, V, S, A> IntoIterator for &'a mut hashbrown::map::HashMap<K, V, S, A>
where A: Allocator,

impl<'a, T, A> IntoIterator for &'a HashTable<T, A>
where A: Allocator,

impl<'a, T, A> IntoIterator for &'a BTreeSet<T, A>
where A: Allocator + Clone,

impl<'a, T, A> IntoIterator for &'a VecDeque<T, A>
where A: Allocator,

impl<'a, T, A> IntoIterator for &'a BinaryHeap<T, A>
where A: Allocator,

impl<'a, T, A> IntoIterator for &'a LinkedList<T, A>
where A: Allocator,

impl<'a, T, A> IntoIterator for &'a Vec<T, A>
where A: Allocator,

impl<'a, T, A> IntoIterator for &'a mut HashTable<T, A>
where A: Allocator,

impl<'a, T, A> IntoIterator for &'a mut VecDeque<T, A>
where A: Allocator,

impl<'a, T, A> IntoIterator for &'a mut LinkedList<T, A>
where A: Allocator,

impl<'a, T, A> IntoIterator for &'a mut Vec<T, A>
where A: Allocator,