Trait IntoIterator

1.0.0 (const: unstable) · 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 (const: unstable) · Source

type Item

The type of the elements being iterated over.

1.0.0 (const: unstable) · Source

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

Which kind of iterator are we turning this into?

Required Methods§

1.0.0 (const: unstable) · 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 &FieldSet

type IntoIter = Iter

type Item = Field

impl IntoIterator for IndexVec

type IntoIter = IndexVecIntoIter

type Item = usize

impl IntoIterator for bytes::bytes::Bytes

type Item = u8

type IntoIter = IntoIter<Bytes>

impl IntoIterator for BytesMut

type Item = u8

type IntoIter = IntoIter<BytesMut>

impl IntoIterator for Error

type Item = Error

type IntoIter = IntoIter

impl IntoIterator for Value

type Item = Subtag

type IntoIter = ShortBoxSliceIntoIter<Subtag>

impl IntoIterator for EventMask

type Item = EventMask

type IntoIter = Iter<EventMask>

impl IntoIterator for WatchMask

type Item = WatchMask

type IntoIter = Iter<WatchMask>

impl IntoIterator for EventKindMask

type Item = EventKindMask

type IntoIter = Iter<EventKindMask>

impl IntoIterator for CipherCtxFlags

type Item = CipherCtxFlags

type IntoIter = Iter<CipherCtxFlags>

impl IntoIterator for CMSOptions

type Item = CMSOptions

type IntoIter = Iter<CMSOptions>

impl IntoIterator for OcspFlag

type Item = OcspFlag

type IntoIter = Iter<OcspFlag>

impl IntoIterator for Pkcs7Flags

type Item = Pkcs7Flags

type IntoIter = Iter<Pkcs7Flags>

impl IntoIterator for ExtensionContext

type Item = ExtensionContext

type IntoIter = Iter<ExtensionContext>

impl IntoIterator for ShutdownState

type Item = ShutdownState

type IntoIter = Iter<ShutdownState>

impl IntoIterator for SslMode

type Item = SslMode

type IntoIter = Iter<SslMode>

impl IntoIterator for SslOptions

type Item = SslOptions

type IntoIter = Iter<SslOptions>

impl IntoIterator for SslSessionCacheMode

type Item = SslSessionCacheMode

type IntoIter = Iter<SslSessionCacheMode>

impl IntoIterator for SslVerifyMode

type Item = SslVerifyMode

type IntoIter = Iter<SslVerifyMode>

impl IntoIterator for X509CheckFlags

type Item = X509CheckFlags

type IntoIter = Iter<X509CheckFlags>

impl IntoIterator for X509VerifyFlags

type Item = X509VerifyFlags

type IntoIter = Iter<X509VerifyFlags>

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 rustix::backend::event::epoll::CreateFlags

Trait IntoIterator