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());

Trait IntoIteratorCopy 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 &BoundedRegSpan

type Item = Reg

type IntoIter = RegSpanIter

impl IntoIterator for Fields

type Item = Field

type IntoIter = IntoIter<Field>

impl IntoIterator for proc_macro::TokenStream

type Item = TokenTree

type IntoIter = IntoIter

impl IntoIterator for proc_macro2::TokenStream

type Item = TokenTree

type IntoIter = IntoIter

impl IntoIterator for regex::regexset::bytes::SetMatches

type IntoIter = SetMatchesIntoIter

type Item = usize

impl IntoIterator for regex::regexset::string::SetMatches

type IntoIter = SetMatchesIntoIter

type Item = usize

impl IntoIterator for CreateFlags

type Item = CreateFlags

type IntoIter = Iter<CreateFlags>

impl IntoIterator for ReadFlags

type Item = ReadFlags

type IntoIter = Iter<ReadFlags>

impl IntoIterator for WatchFlags

type Item = WatchFlags

type IntoIter = Iter<WatchFlags>

impl IntoIterator for Access

type Item = Access

type IntoIter = Iter<Access>

impl IntoIterator for AtFlags

type Item = AtFlags

type IntoIter = Iter<AtFlags>

impl IntoIterator for FallocateFlags

type Item = FallocateFlags

type IntoIter = Iter<FallocateFlags>

impl IntoIterator for MemfdFlags

type Item = MemfdFlags

type IntoIter = Iter<MemfdFlags>

impl IntoIterator for Mode

type Item = Mode

type IntoIter = Iter<Mode>

impl IntoIterator for OFlags

type Item = OFlags

type IntoIter = Iter<OFlags>

impl IntoIterator for RenameFlags

type Item = RenameFlags

type IntoIter = Iter<RenameFlags>

impl IntoIterator for ResolveFlags

type Item = ResolveFlags

type IntoIter = Iter<ResolveFlags>

impl IntoIterator for SealFlags

type Item = SealFlags

type IntoIter = Iter<SealFlags>

impl IntoIterator for StatVfsMountFlags

type Item = StatVfsMountFlags

type IntoIter = Iter<StatVfsMountFlags>

impl IntoIterator for DupFlags

type Item = DupFlags

type IntoIter = Iter<DupFlags>

impl IntoIterator for FdFlags

type Item = FdFlags

type IntoIter = Iter<FdFlags>

impl IntoIterator for ReadWriteFlags

type Item = ReadWriteFlags

type IntoIter = Iter<ReadWriteFlags>

impl IntoIterator for IFlags

type Item = IFlags

type IntoIter = Iter<IFlags>

impl IntoIterator for StatxAttributes

type Item = StatxAttributes

Trait IntoIterator